Program - Symposium B: Heterogeneous Integration Challenges of MEMS, Sensor, and CMOS LSI

2012 MRS Spring Meeting logo

2012 MRS Spring Meeting & Exhibit

April 9-13, 2012San Francisco, California
Download Session Locator (.pdf)2012-04-11  

Symposium B

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Symposium Organizers

  • Kazuya Masu, Tokyo Institute of Technology
  • Kazuaki Sawada, Toyohashi University of Technology
  • Hiroshi Toshiyoshi, The University of Tokyo Institute of Industrial Science
  • Benoit Charlot, Université Monptellier II Institute d'Electronique de Sud
  • Albert P. Pisano, University of California, Berkeley

Support

  • Japan Society of Applied Physics

    B1: RF

    • Chair: Kazuya Masu
    • Wednesday PM, April 11, 2012
    • Moscone West, Level 2, Room 2000
     

    1:30 PM - *B1.1

    A Creep-Immune RF-MEMS Tunable Capacitor with Quadruple Series Capacitor Structure

    Yoshiaki  Shimooka1, Hiroaki  Yamazaki1, Etsuji  Ogawa1, Tomohiro  Saito1, Tamio  Ikehashi1, Yoshiaki  Sugizaki1, Hideki  Shibata1.

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    RF-MEMS tunable capacitors are suitable for tunable components of multiband/multimode mobile handsets because of their low loss and excellent linearity [1]. In order to use the RF-MEMS tunable capacitor in a mobile system, a high power-handling is needed. The RF-MEMS tunable capacitors have an issue of creep-induced deformation. The creep is caused by a ductile metal like aluminum alloy which is indispensable to attain the low loss. From this point of view, we have developed an RF-MEMS tunable capacitor that has compatibility of CMOS device integration processes and achieved high power-handling capability and excellent creep immunity. The tunable capacitor has a quadruple series capacitor (QSC) structure, which consists of two MEMS capacitor elements and two fixed metal-insulator-metal (MIM) capacitors connected in series between input and output terminals [2]. The QSC structure drastically improves the power-handling, since the voltage applied by RF signals can be reduced at the each MEMS element. We fabricated a digitally tunable capacitor bank that consisted of the eight QSC structure elements. The capacitance of the bank changes widely from 1.9pF to 5.5pF at 1GHz. The quality factor is good in 114 and 80 for the minimum and maximum capacitance, respectively. Next, an RF power handling characteristic was evaluated by measuring the pull-out voltage dependence on the input RF power. The result shows that the fabricated tunable capacitor bank can handle the RF signal up to +36dBm under the hot-switching conditions at even 85°C. The springs that support the top electrode of each MEMS capacitor element were formed by a silicon nitride (SiN) dielectric material [2, 3]. We examined simply parallel plate actuators to analyze the creep of springs and saw that the creep-induced deformation was reduced drastically by forming the SiN springs instead of aluminum springs. The creep deformation of the actuator with SiN springs was drastically reduced by one twenty-third at 85°C, compared to aluminum springs. We also carried out a cycle test for the actuator with SiN springs and observed no failures up to 109 cycles at 25°C. We demonstrated an RF-MEMS tunable capacitor using a quadruple series capacitance structure with SiN springs. The excellent quality factor was achieved at the large capacitance owing to the low loss structure. The proposed RF-MEMS tunable capacitor is also shown to have high power-handling and good long-term creep immunity properties. References: [1] G. M. Rebeiz, RF MEMS: Theory, Design, and Technology, Wiley Interscience, 2003. [2] H. Yamazaki et al, “An RF-MEMS Tunable Capacitor Using Quadruple Series Capacitor Structure and Brittle Material Springs”, Proc. of ADMETA 2010: 20th Asian Session, pp.80-81. [3] E. Ogawa et al, “A LONG-TERM RELIABILITY ANALYSIS OF A CREEP-IMMUNE RF-MEMS TUNABLE CAPACITOR”, Proc. of Transducers 2011, pp. 2466-2468.

    2:00 PM - B1.2

    An Electromechanically Driven, Fast, Low Power Switch: The Piezotronic Transistor

    Glenn  J  Martyna1, Dennis  M  Newns1, Bruce  G  Elmegreen1.

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    After decades of rapid increase, clock speeds of computers plateaued in 2003 due to the breakdown of Dennard's constant-electric-field scaling rules. The basic physics of CMOS field effect transistor (FET) operation, controlling current low via the imposition of a (electrical) potential barrier, is at the root of the problem which cannot then be overcome by engineering methods, alone. In order to respond to the challenge posed by clock speed plateau, it is necessary to embody novel physical principles in new designs. Inspired by the power of piezoelectrically driven MEMS switches, a new device, the Piezoelectronic Transistor (PET) is proposed. The PET utilizes a high response relaxor piezoelectric material to mechanically compress a correspondingly high response piezoresistive material upon receipt of an input voltage signal. The piezoresist then undergoes a pressure driven continuous metal insulator transition (MIT). The MIT, in one instance an intermediate valence transition, opens a channel for current flow. In this talk, it will be shown how the physics and materials science underlying the PET's elecromechanical operation coupled to its geometric design can circumvent the limitations of the FET. The result is a fast (~5GHz), low voltage (~0.1V) switch that consumes ~100x less power than CMOS. We emphasize that the properties of known materials are sufficient to realize the PET via theoretical analysis and simulation and present the 1st experimental demonstrations of critical components of the PET device. The project is funded through DARPA's MESO II program.

    2:15 PM - B1.3

    The Integration of the Ferromagnetic Inductors into the Standard CMOS Chip

    Oleg  Nizhnik1, Olinver  Vinluan1, Koji  Sonoda1, Masatoshi  Ishii1, Kohei  Higuchi1, Kazusuke  Maenaka1.

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    1. Previous Attempts Many research groups have tried to integrate ferromagnetic-based inductors into CMOS chips. Using ferromagnetic material has the following advantages: increased inductor reactance at low frequency, increased coupling of transformers and reduced fringe fields of all magnetic components. Reduced fringe fields allow an increase in the level of integration for system-on-chip schemes. But ferromagnetic material is not easy to integrate in CMOS chips. The main problem is the extreme thinness of the portion of CMOS chips that is usable for magnetic circuits (oxide-metal stack on top of the CMOS). With a typical stack thickness of 5um and flat coil geometry, 1 mm inductor will result in an aspect ratio of 200:1. Attempts to use the backside of the CMOS chip for the magnetic circuits were largely thwarted by the losses in the silicon between the metal coil and ferromagnetic layer. The silicon eddy current loss also significantly degraded performance of designs where the metal coil was sandwiched between two ferromagnetic layers within the metal-oxide stack of the CMOS, Furthermore, materials suitable for well-controlled deposition on the CMOS chip are very few. Therefore, no single material was satisfactory in terms of the magnetic permeability, hysteresis and eddy current losses. 2. Concept Description The main concept for the current research was the design of the ferromagnetic integration strategy into CMOS, being free from the disadvantages of the previous attempts. To do this, multiple criteria listed below must satisfied: a) Deposited material’s thickness must be well controlled and small in order to not hamper flip-chip assembly. b) Deposited materials must be non-magnetic in bulk form (to facilitate RF sputtering, a precise deposition method) but must form a ferromagnetic layer on top of the chip. Materials satisfying this criterion were Fe-Co-Si-B alloy and ZnFe2O4. c) There must be no silicon around the magnetic circuits. In the proposed design, silicon is back-etched under the inductor. d) Magnetic components must produce a closed magnetic circuit and must be immune to delamination. To satisfy this criterion, same layers of ferromagnetic material were deposited on the top and bottom of the metal-oxide stack. e) The tradeoff between permeability and eddy currents must be easily controlled to satisfy the application requirements. To do this, a multilayer composite of Fe-Co-Si-B and ZnFe2O4 was used. f) The ferromagnetic materials must be compatible with CMOS post-processing techniques. This means the ferromagnetic must resist handling stress, and processing must be done at low temperatures. 3. Results Achieved Inductors with under-etched silicon, up to 8 ferromagnetic layers, and metal coil diameters around 0.8mm wide were fabricated. The peak quality factor increased from 8 to 11. The low-frequency inductance increased from 41.5nH to 67.0nH, and low-frequency quality factor increased from 0.6 to 5.1.

    2:30 PM - B1.4

    Electromechanical Properties of Al0.9Sc0.1N Thin Films Evaluated at 2.2 GHz Film Bulk Acoustic Resonators

    Ramin  Matloub Aghdam1, Evgeny  Milyutin1, Alvaro  Artieda1, Silviu Cosmin  Sandu1, Paul  Muralt1.

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    Since a few years, aluminum nitride (AlN) thin films have become a standard material for RF filters in mobile phones. It is mostly used in duplex filters working around 2 GHz composed of thin film bulk acoustic wave resonators (TFBAR) connected in ladder type circuits. Pure AlN thin films were found to have maximal d33,f piezoelectric coefficients of 5.3 pm/V. The coupling coefficients of TFBAR’s amounts to maximally k2=6.5 % considering standard materials parameters. Such a value is sufficient for covering the needs of current filter requirements for mobile phones. However, there are other filters types and applications that would require larger coupling factors in order to achieve larger bandwidths. Recently it was shown that Al substitution by Sc allows for an increase of the piezoelectric response. We prepared polycrystalline (001)-textured Al0.88Sc0.12N thin films by reactive, pulsed, direct current magnetron sputtering to measure all relevant properties for TFABR resonators. The target was a 200 mm diameter, 6 mm thick plate of an Al0.9Sc0.1 alloy of 99.9% purity and exact composition Al/Sc of 89.76 at. %/10.23 at. %. Selected area electron diffraction calibrated with the XRD (002) peak yielded a and c lattice parameters of 3.11 and 5.01 Å, respectively. The c/a ratio decreased to 1.575 from 1.601 of pure AlN. The unit cell volume increased by 5%. Energy dispersive analysis of x-ray emission in the TEM revealed that 12 at. % of Al atoms were substituted by Sc, indicating a higher sputter or transfer yield for Sc. The microstructure of the films as investigated by means of TEM is very close to the known picture of fiber type T-zone growth of good AlN thin films for TFBAR’s. The clamped piezoelectric coefficient d33,f as measured by double side interferometry increases to 7.7 to 8.0 pm/V. TFBAR resonators with fundamental resonance at 2.2 GHz have been fabricated and characterized. The sound velocity in AlScN was derived by means of 2D finite element modeling of the layer stack, allowing for discrimination of loading effects by the electrodes. The value of 10’300 m/s is clearly lower than in pure AlN (11’000 m/s). A parasitic resistance was taken into consideration through application of an equivalent circuit model. As a result of these procedures we obtained k2 to 11 % and Q factor of 400 for the complete resonator, furthermore a dielectric constant of 12.5, and a dielectric loss tangent of 0.5% (both @2.2 GHz). The stiffness constants cD33 and cE33 were derived as 345 and 320 GPa. The resonance frequency temperature drift of 26.1 ppm/K was found to be about the same as for pure AlN. The evolution of piezoelectric constant e33, the dielectric constant, and the stiffness constant were found to be close to the values predicted by ab-inito calculations.

    2:45 PM - B1.5

    3D Heterogeneous Integration Using MEMS Devices for RF Applications

    Fumihiko  Nakazawa2 1, Xiaoyu  Mi2 1, Tadashi  Nakatani2 1, Takeaki  Shimanouchi2 1, Osamu  Toyoda2 1, Satoshi  Ueda2 1.

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    This paper presents 3D heterogeneous integrations for RF applications. A miniaturized duplexer and a MEMS tunable filter, combining the advantages of LTCC, passive integration and MEMS technologies, were constructed to demonstrate its feasibility and effectiveness. Frequency property influence in the 3D integration of a PZT actuated MEMS switch using a single crystal silicon asymmetric beam is studied. A duplexer module has been constructed using 3D heterogeneous integration method. The duplexer consists of a film bulk acoustic resonator (FBAR) transmission (Tx) filter, a single-to-balanced double mode SAW (DMS) receiver (Rx) filter, and notch and matching circuits. Part of the notch and matching circuits were built inside the LTCC wafer and the rest were directly formed on the LTCC wafer surface. The SAW and FBAR filter are mounted above passive circuits formed on the surface of LTCC wafer. The fabricated module measures a compact 2 mm x 2.5 mm x 0.55mm. A low insertion loss of less than 1.7 dB has been achieved in either Tx or Rx band. Resistive vias builted inside the LTCC wafer were used to isolate the RF signal from DC driving line in a MEMS-varactor-based tunable filter. The movable upper electrode and DC driving electrodes of the MEMS varactors are connected to DC driving pads through inner resistive vias and inner wiring. These built-in resistive vias are placed directly under the MEMS without occupying any surface area. The insertion loss of the MEMS tunable filters is improved from -6.8dB to -2.3dB thanks to the integrated resistive vias blocking RF leakage into the DC driving path. Our metal-to-metal contact RF-MEMS switch has a single crystal silicon (SCS) fixed-fixed beam, on which a PZT unimorph actuator and a bottom RF signal electrode are patterned. The beam is separated from the fixed part by a slit. A bridge-shaped top RF signal line is formed above the beam by electroplating with narrow air-gap. An RF-ground surrounds the switch to improve impedance matching. The fixed beam is designed in an asymmetric shape, and in order to reduce actuation voltage, the portion with the bottom electrode is narrower and longer than the other portion with the PZT actuator. Our beam was very stiff (>2,000 N/m of spring constant) in order to reduce undesirable deflection. Measured performance of the insertion loss was 0.2 dB up to 2GHz, and 0.3 dB up to 5GHz. The isolation was -33 dB up to 2GHz, and -25 dB up to 5 GHz. The main factor of the insertion loss is the resistance of the sputtered bottom signal line which is 0.9 ohm. Simulation of the frequency property influence of 3D integration was carried out with the RF MEMS switch with a ground plane placed over it. The ground plane is used as a worst case coupling effect of the control IC, which has a wide metal layer built in. Isolation and insertion loss was simulated with a parameter of distance between the RF MEMS switch and the ground plane.

    3:00 PM -

    BREAK

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    B2: Device

    • Chair: Hiromu Ishii
    • Wednesday PM, April 11, 2012
    • Moscone West, Level 2, Room 2000
     

    3:30 PM - *B2.1

    Overview of MEMS / NEMS Application to Hard-disk Drives (HDDs)

    Toshiki  Hirano1.

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    This presentation will give an overview of Micro-Electro-Mechanical Systems (MEMS) and Nano-Electro-Mechanical Systems (NEMS) application to hard-disk drives (HDDs). Examples will include: Magnetic head (thermal actuator for thermal fly-height control, thermal sensor for head-disk contact detection), tracking-servo micro-actuators (suspension based, moving-slider, and moving element), acceleration sensor for vibration feed-forward, Bit Patterned Recording (nano-fabrication of master pattern, nano-imprint), and Heat-Assisted Magnetic Recording (near-field transducer).

    4:00 PM - B2.2

    Narrow Gap Structure for Nanoampere-level Current Generation in a Millimeter-sized Vibrational MEMS Electrostatic Energy Harvester

    Kazuyoshi  Ono1, Norio  Sato1, Toshishige  Shimamura1, Mamoru  Ugajin1, Tomomi  Sakata1, Shin'ichiro  Mutoh1, Junichi  Kodate1, Yoshito  Jin1, Yasuhiro  Sato1.

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    Future ubiquitous wireless sensor networks will require small and thin autonomous sensor nodes, which contain a radio, power manager, transducers, and energy harvesters. To realize an autonomous operation of the sensor node, nanowatt-level power management circuit has been developed. The circuit required the energy harvester to be within millimeter-size, and generate at least nanoampre-level current. For this purpose, we have proposed a vibrational MEMS energy harvester with slit-and-slider electrodes and electret, and the current of 0.17 nA has been generated. However, the generated current was not sufficient to operate even the power management circuit because it was one-order lower than the required one. Therefore, it is important to boost the current in the limited millimeter-sized structure. This can be done by improving charge in electret. Another approach, which we undertook here, is to change of the structural parameters. In this work, we focused on the gap between the slit-and-slider electrodes in the energy conversion region as the structural parameter. The point is to achieve a large variable capacitance change between the electrodes. We fabricated a millimeter-sized MEMS vibrational energy harvester by bonding the slit electrode chip with the slider electrode chip while narrowing the gap between the slit-and-slider electrodes. We prepared bonded devices with gaps of 5, 15, and 30 μm. To evaluate the effect of narrowing the gap between the electrodes, we measured electromechanical characteristics. Under a bias voltage, which induces electric charge between the electrodes, the devices were vibrated by a shaker in the direction parallel to the devices. When the external vibration is applied to the device, the movable slider plate suspended by springs is displaced. Corresponding to the displacement, the capacitance between the electrodes is varied, which induces a current on the load resistor in a lock-in amplifier. The acceleration of the stage and the bias voltage were set to two meter per second squared and 30 V, respectively. For the gaps of 5, 15, and 30 μm, the currents of 0.37, 1.09, and 1.62 nA were obtained. The current was inversely proportional to the square of the gap, which corresponds to the fomula for a capacitance with a fringe effect. We confirmed nanoampere-level current generation with the external bias voltage, which corresponds to a charged electret. The current of the 5-μm gap is about more than 10 times larger than that for the 30-μm gap, indicating that the generated output power is dramatically increased by narrowing the gap. This result shows that narrowing the gap increases the generated output power effectively in the millimeter-size vibrational MEMS energy harvester, which will contribute to the development of energy sources for sensor nodes.

    4:15 PM - B2.3

    Quantum Size Effects on the Performance of Chemical Sensors

    Junghyo  Nah1, Bala  Kumar2, Fang  Hui1, Ali  Javey1, Jing  Guo2.

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    The use of nanomaterials for sensor applications has been widely explored in the past since they provide higher sensitivity as well as lower detection limits as compared to their bulk or thick film counterparts. In general, enhanced sensor responses in nanomaterial-based gas sensors are attributed to the high surface-to-volume ratio of nanomaterials. However, the detailed impact of various size effects, including the role of quantum confinement in determining the sensor response is still not well established. Here, we explore the quantum size effects on the sensing performance of the ultrathin InAs membranes gas sensor. For this study, we employed layer-transferred InAs ultrathin films on SiO2/Si substrates, resulting in InAs-on-insulator (XOI) structure. The top surfaces of three different InAs thicknesses (8, 18, 48 nm) were functionalized with Pd nanoparticles to enable H2 sensing. InAs is an ideal material platform for exploring the quantum size effects given its large Bohr radius of ~35 nm, which results in the population of only one 2-D subband at room temperature for sub-10 nm thicknesses. Using these sensor devices, we experimentally and theoretically examined the role of InAs thickness scaling on the gas sensor response. We observed substantially improved sensor responses as the InAs thickness scales down. The role of the InAs thickness scaling on sensor performance is two-fold. First, electrostatic control of carrier concentrations by Pd-functionalized surface reaction with H2 is enhanced with the thickness scaling. More importantly, quantization effects, clearly observed in the ultrathin InAs membrane, significantly alter the electron mobility of the sensor device and cause drastic change in currents upon H2 exposure, resulting in high sensor responses. The latter is due to the enhanced surface scattering rates of electrons in quantum confined membranes which make them more susceptible to surface phenomena. The work here presents a new insight into the role of carrier quantization in the response of sensor devices with important practical implications.

    4:30 PM - B2.4

    A Low-voltage and High Uniformity NEMS Tunable Color Filter Based on Subwavelength Grating

    Hiroaki  Honma1, Kazuhiro  Takahashi1, Makoto  Ishida1, Kazuaki  Sawada1.

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    This paper reports a NEMS (Nano Electro Mechanical Syetems) tunable color filter based on subwavelength grating with high color uniformity and low drive voltage. The developed tunable color filter was demonstrated a structural color change at drive voltage of 6.7 V. MEMS tunable color filters based on subwavelength grating are expected to have high diffraction efficiency and wavelength selectivity [1]. We have previously developed a NEMS tunable color filter that consists of an array of parallel-plate actuators with a nano gap, which was demonstrated a structural color change at drive voltage of 20 V [2]. Monolithic integration process with MOS driver circuit has been reported in Transducers ’11 [3]. However, each actuator placed with the nano gap had a crosstalk of an electrostatic attraction force, which made non-uniformity color and relatively high drive voltage. For improving the uniformity and decreasing the drive voltage, we newly propose a GVG (Ground-Voltage-Ground) type NEMS tunable color filter deployed with an array of a parallel-plate actuator with three pairs of electrode. The electrostatic parallel-plate actuator for the color filter is formed from three silicon beams. A fixed electrode is located in the middle, and movable electrodes are set on either side. A drive voltage and ground level are provided to the fixed middle electrode and movable electrodes, respectively. The pitch of the subwavelength grating is changed due to the electrostatic force. Movable electrodes are attracted to the middle fixed electrode without any crosstalk. In an analytical model for FEM (Finite Element Method), we design the subwavelength grating to be 220 nm wide, 380 nm gap and 30 microns long and 150 nm thick. The suspension is set to 10 microns long and 150 nm wide. The pull-in voltage is found at 4 V. In addition, the simulation result is depicted that the GVG structure provides a uniform displacement in arrayed actuators, which produces uniform color in whole filter area. The fabricated tunable filter was 30 µm×30 µm in area, which is configured by a 25 pairs of parallel-plate actuators. The grating beam was 240 nm wide, 150 nm thick, and 30 microns long with the gap of 260 nm. The suspension dimensions were 10 µm long and 200 nm wide. The color filter was measured by a spectrometer. The experimentally shifted color is plotted on the CIE chromaticity chart, (x,y)=(0.348, 0.467) at initial position and (0.325, 0.449) at 6.7 V. The color uniformity was also obtained in the filter area. In conclusion, the GVG type NEMS tunable color filter is possible to operate by standard CMOS-LSI circuit. The tunable color filter reported here is expected to develop a new display application. [1] K. Hane, et al., Applied Physics Letters, Vol. 88, p.141109 (2006) [2] H. Miyao, et al., 219th ECS meeting, 1-6 May, 2011, Montreal, Canada, pp. 213-218. [3] H. Honma, et al., Proc. TRANSDUCERS ’11, 5-9 June, 2011, Beijing, China, pp. 2928-2931.

    Download Session Locator (.pdf)2012-04-12  

    Symposium B

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    Symposium Organizers

    • Kazuya Masu, Tokyo Institute of Technology
    • Kazuaki Sawada, Toyohashi University of Technology
    • Hiroshi Toshiyoshi, The University of Tokyo Institute of Industrial Science
    • Benoit Charlot, Université Monptellier II Institute d'Electronique de Sud
    • Albert P. Pisano, University of California, Berkeley

    Support

    • Japan Society of Applied Physics

      B3: Sensor

      • Chair: Kazuaki Sawada
      • Thursday AM, April 12, 2012
      • Moscone West, Level 2, Room 2000
       

      8:30 AM - *B3.1

      Laminate MEMS for Heterogeneous Integrated Systems

      Gp  Li1, Mark  Bachman1.

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      The unprecedented technology advancements in miniaturizing integrated circuits on silicon (SOC) and in integrating systems in a package (SIP) have demonstrated the impact that dimension scaling engineering can have for communication, computing, and consumer electronics. While a silicon manufacturing technology has been applied to constructing various Micro Electro Mechanical System (MEMS) for integrating additional sensing and actuation functions into microelectronics silicon chips, post silicon MEMS chips packaging remains to be very challenging. On the other hand, post semiconductor manufacturing processes (PSM), including packaging and printed circuit board (PCB) technologies with a few micrometer line and space resolution and sub-mil vias are readily achievable. Such PSM technology can be used to manufacture micro electromechanical systems (MEMS) for sensing and actuation applications. A lamination-based manufacturing process allows for a broader selection of materials and fabrication processes than silicon-based manufacturing, and therefore provides greater design freedom for producing functional microdevices. In many cases devices can be fabricated that are more suited to their applications than their silicon counterparts. Furthermore, such microdevices can be built with a high degree of integration, pre-packaged, and at low cost. Indeed, the PCB and packaging industries stand to benefit greatly by expanding their offerings beyond serving the semiconductor industry and developing their own devices and products. This paper illustrates that good quality MEMS devices can be manufactured in laminates, and discusses some of the unique benefits of such devices. This laminate MEMS technology promises for not only manufacturing microdevices but also heterogeneously integrating them with silicon microelectronics into their package with the same manufacturing processes.

      9:00 AM - B3.2

      MEMS-CMOS Integrated Tactile Sensor with Digital Signal Processing for Robot Application

      Mitsutoshi  Makihata1, Masanori  Muroyama1, Shuji  Tanaka1, Hitoshi  Yamada2, Takahiro  Nakayama2, Ui  Yamaguchi2, Yutaka  Nonomura3, Motohiro  Fujiyoshi3, Masayoshi  Esashi1.

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      An ultra-small tactile sensor with the functions of signal processing and digital communication has been prototyped by using MEMS-CMOS integration technology. The designed analog-digital mixed ASIC allows many tactile sensors to connect a common bus line, which drastically reduces the number of wire. The wafer-level integration and packaging technology realizes a chip-size-package (CSP) with small footprint (2.5mm×2.5mm) and low profile (0.27mm), which is convenient for surface mounting on a curved robot body. The MEMS structure and the ASIC are stacked at wafer level, and the I/O pads which are sealed at bonding interface are connected to the backside of the tactile sensor using novel through-silicon-vias (TSV). The TSV are made in tapered grooves, which are sawed using a dicing blade. Finally, the integrated tactile sensor was tested, and the digital data which was fired autonomously like a tactile receptor of human was observed. In recent year, the tactile sensor which can be densely distributed on relatively large area (1~2m2) is needed for humanoid robots. However, the wiring and data processing become critical issues as the number of tactile sensor increases. The integration of a MEMS tactile sensor with ASIC solves the issues by digital communication and data processing function. Digital communication enables the mounting of many sensors on a common few-wires cable, which is drastically reduces the number of wire. ID number, sensing data and CRC (Cyclic Redundancy Check) are contained in the digital output data to distinguish the digital data on the common cable. The sensing part stacked on the ASIC is a Si diaphragm capacitive force sensor, which also works as a grounded sealing for the ASIC surface. To achieve surface mounting, the electrical feeding-through of the I/O pads from the bonding interface to the backside is necessary. In contrast to standard TSV technology, which uses deep-reactive-ion-etched holes, we used tapered grooves fabricated by mechanical dicing with a V-shape blade. 55 degree tapered and 70μm deep grooves are fabricated around the ASIC chip area. The grooves are insulated by PECVD. Then, redistributed electrodes from the I/O pad are extended to the bottom of the grooves, and the grooves are filled by benzocyclobutene (BCB). After the wafer bonding between the Si sensing structure (200μm thick) and the ASIC (780μm thick), the filled grooves are exposed by back-grinding the ASIC wafer. The exposed pads are redistributed again and forms LGA (land grid array) type electrodes. The developed integration and packaging technology is applicable to standard CMOS, versatile and low cost. After the fabrication, the tactile sensor was tested. The yield of the electrical feed-through is 100% (160pin/160pin). 80bit long digital data, which were autonomously fired every second, was observed. The sensing data without force stimulus shows a sensor capacitance of 1.7pF, which roughly agree with the designed value.

      9:15 AM - B3.3

      Heterogeneous Integration of LSI Amplifier and the Tactile Sensor Using Stacking and through-Si-via Techniques

      Masayuki  Sohgawa1, Hokuto  Yokoyama1, Takeshi  Kanashima1, Masanori  Okuyama1, Haruo  Noma2.

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      In recent years, there have appeared serious problems concerning the relative increase in the aged population and the reduction in the working population in many countries. Therefore, care of the aged and automation in manufacturing have become very important in solving these problems, and human-support robots with skillful performance have attracted much attention. In order to produce the skillful and dexterous robot, excellent sensors are required to detect condition of the object and especially tactile sensor is much valuable for holding the object in the nurse care and the automation. We have developed the tactile sensor using the microcantilevers with gauge film, fabricated by MEMS technologies and embedded in the elastomer, and the sensor can detect normal and shear forces simultaneously. However, there appear some problems. One is the signal noise in the sensor output generated in the long wire from the sensor elements to the amplifier. The other is a number of wires for collecting many signals of distributed sensor arrays. In this work, the tactile sensor chip and the LSI amplifier chip have been integrated heterogeneously to shorten the wire length and reduce the noise in the output voltage. Moreover, it is considered that integration of the tactile sensor and the signal amplifier can reduce the sensor size and wiring numbers, and allows installation of more sensors on fingertips of the robot. Firstly, the LSI amplifier chip was mounted on the surface of the tactile sensor chip (chip-on-chip). After fabrication of wires and microcantilevers with gauge film on the SOI wafer using surface micromachining, the microcantilevers were embedded in the elastomer (PDMS). Then, the LSI amplifier was inter-connected with sensors through electrical pads by Au wires. The noise (peak to peak) can be reduced from 750 mV to 120 mV by heterogeneous integration of the tactile sensor and the LSI amplifier. Next, the LSI amplifier was mounted on the backside of the sensor chip using through-silicon-via (TSV) holes instead of Au wires. The thickness of SOI wafer was reduced to 300 μm by polishing and via holes of diameter 55 μm were made by deep reactive ion etching (RIE). Silicon nitride film was deposited on the sidewall of the holes by LPCVD and the holes were filled with Cu plating. Then, projecting surface of TSV Cu was polished by chemical mechanical polishing (CMP). The average resistance of TSV holes, 3-4 Ω is enough low and insulation between holes is good (its resistance is over 50 MΩ). Moreover, these resistance values are not changed by dipping into buffered HF solution (NH4HF2: 20%) for 5 hours of sacrificial etching so that TSV holes are not damaged to fabricate the microcantilevers. Therefore, it is demonstrated that the LSI amplifier chip can be mounted on the backside of the sensor chip and the size of sensor chip can be shrunk to 5 mm square using TSV.

      9:30 AM - B3.4

      A New Type pH Sensor with Super High Sensitivity

      Fumihiro  Dasai1, Ryota  Otake1, Daiki  Suzuki1, Masato  Futagawa1, Makoto  Ishida1, Kazuaki  Sawada1.

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      In our previous works, a charge transfer type of pH-sensor had been proposed. This pH-sensor was able to amplify the sensing signal by charge accumulation without using an external amplifier and was able to achieve a high S/N ratio as compared to the conventional type Ion-sensitive-field-effect-transistor (ISFET). However, when electron energy between sensor bottom and ICG (Charge Injection Gate) bottom are close (in other words, when output level is low), this pH-sensor has a potential barrier between the ion-sensitive area and ICG. This potential barrier causes unexpected charge that is remained on the sensing area. We called this ‘the charge of the false signal’. So the number of accumulation was limited to 2 or 3, because this charge of the false signal accounts for 20% of the maximum output range, and also is amplified simultaneously with the charge of the true signal. To solve this problem, we proposed a new type of sensor. This sensor has a second gate on the potential barrier to suppress it. However, this structure needed the double layer Poly-Si process and was unsuitable in order to miniaturize sensor pixels for a two-dimensional array sensor. We propose a new type of pH-sensor in this paper. This sensor has a gate (Q-trap gate) that is formed next to the pH-sensing area by a first Poly-silicon. The new sensor operates by, first filling the potential well at the bottom of sensor area for the electron, and next, transforming the potential level of Q-trap gate from low to high. As a result, the deep electric potential well is formed under the Q-trap gate. On this operation, the charge of false signal is trapped from the pH signal charge that is stored up in the electric potential well under the sensing area. After this operation, transmission gate (TG) between the sensor area and the floating diode is turned on, and the true signal charge without the charge of the false signal is transferred to FD. By doing this, we can get the true signal voltage. We made this new type of pH sensor and evaluate it with 2um CMOS 1P1M process. As the evaluation, we have confirmed that the false signal charge was erased completely. As a result, the charge of the false signal accounted for 20% of the maximum output range in the conventional structure, has no effect on this new type of pH sensor. And we could accumulate the pH signal 15-times. (The number of accumulate was limited by the measurement equipment). So, we will be able to develop a super-high-sensitive two-dimensional array sensor shortly by using this Q-trap structure without the complicated wafer process. Reference [1] Kazuaki Sawada, T. Shimada, T. Ohshima, Hidekuni Takao, Makoto Ishida "Highly sensitive ion sensors using charge transfer technique, SENSORS AND ACTUATORS B, Vol.98,pp. 69-72, 2004 [2] Ref: J. Matsuo, T. Hizawa, K. Sawada, H. Takao and M. Ishida, "Charge Transfer Type pH Sensor with Super High Sensitivity", TRANSDUCERS'07, 2, pp.1881-1884 (2007)

      9:45 AM - B3.5

      AlGaN/GaN Heterojunction Field Effect Transistors (HFETs) for DNA Hybridization Detection

      Resham  Thapa1, Siddharth  Alur1, Kyusang Kim  Kim1, Fei  Tong1, Yogesh  Sharma1, Jing  Dai2, Moonil  Kim3, Claude  Ahyi1, Jong  W  Hong2, Michael  Bozack1, John  Williams1, Ahjeong  Son4, Amir  Dabiran5, Andrew  Wowchak5, Minseo  Park1.

      Show Abstract

      Among the numerous techniques that are available for the detection of biomolecules, AlGaN/GaN Heterojunction Field Effect Transistors (HFETs) based sensors present an attractive alternative. They offer simpler, faster and label-free detection route. The key advantages of using III-Nitride heterostructure based FET sensors include higher sensitivity, arising from the two dimensional electron gas (2DEG) at the heterojunction interface, and better chemical/thermal stability even at elevated temperatures without a complicated fabrication process. The intrinsic charge of the biomolecules affects the surface states of the HFET thereby affecting the carrier concentration at the 2DEG channel. The proximity of the 2DEG to the surface helps in achieving very high sensitivity in these devices. The biofunctionalization at the gate electrode alters the transistor characteristics, leading to the fast and label-free detection of biomolecule analytes. Device fabrication process started with the successive steps of mesa etching, and deposition of both ohmic and Schottky contacts. After the wire bonding, photopatternable spin-on silicone was used to encapsulate the device except for the gate region. To immobilize the aminated probe DNA (5′-/5AmC6/CGCTTGAAGAGGTCAATGGCCA-3′), the device was immersed into an ethanol solution of 11-MUA,(HS(CH,2)10,CO,2,H)for 18 hrs. The OH-terminated functional group was then activated with the mixture of EDC (C,8,H,17,N,3.HCl) and sulfo-NHS (C,4,H,4,NNaO,6,S) to react with the amine group present in the probe DNA. This covalent attachment of the aminated probe has been chosen to increase the specificity of the sensor. The incorporation of the 11-MUA on the gate electrode results in a self-assembled monolayer (SAM) by gold-thiol bonding which electrically behaves as a dielectric capacitor. Thus, the detection is based upon the successive capacitive coupling of the intrinsic charge from the DNA and the redistributed ions from the buffer in the double layer. Both I-V and I-t characteristics of the transistor were measured during the immobilization and hybridization of the DNA molecules. Based on the change in current after hybridization, we were able to differentiate the hybridization of the complementary target DNA (5′-TGGCCATTGACCTCTTCAAGCG-3′) from that of 3 base pair mismatched target DNA (5′-TGGACATTGACCTATTCAAGAG-3′). Therefore, we have successfully demonstrated specific detection of DNA using III-nitride HFETs with amine-based biofunctionalization.

      10:00 AM -

      BREAK

      Show Abstract

      B4: Bio I

      • Chair: Kazuya Masu
      • Thursday AM, April 12, 2012
      • Moscone West, Level 2, Room 2000
       

      10:30 AM - *B4.1

      Samrt Micro Sensing Chips for Life Innovation

      Makoto  Ishida1 2, Kazuaki  Sawada1 2, Takeshi  Kawano1, Daisuke  Akai2.

      Show Abstract

      Development of silicon sensing devices with Integrated Circuits using MEMS/NEMS technology will realize an ideal sensing chip, which may be called as “Smart micro chips”, and results in ideal sensor chips, which have several sensor devices, signal processing circuits, rf transmitters, and power supply using natural energy. In this presentation, smart micro-sensor-chips for monitoring of neural activities, real time monitoring of pH image to biochemical, biomedical and clinical applications are presented in our developed chips. Also, a novel Radio Frequency (RF) induced power supply system and on-chip antenna for micro sensor nodes is studied. Integration of radio frequency transmitter (RF) technology with CMOS/MEMS micro-sensors is required to realize the wireless smart micro-sensors system. In our developed chips, one is Si microprobe electrode and tube array chips for recording of neurons in the tissue and drug deliver use. The probe array can be fabricated on IC chips, using standard IC process followed by a selective Si probe growth. The developed chips is a smart silicon microprobe array chips to record neural activities for analysis of the mechanism of retina and brain, or for neural interfacing. The microelectrode array chip with extremely-fine, in other words, low-invasive silicon probes of 1-2um diameter, and fabricated using standard CMOS process followed by the selective vapor-liquid-solid (VLS) growth method. Using the chip, the feasibility of in-vitro recording of neural activities in a carp retina and of in-vivo recording of the peripheral nervous activity of a rat was demonstrated. Another one is pH image sensor chips. 32 × 32 pH image sensors were successfully fabricated by using the CCD/CMOS image sensor technique, and real time imaging of a chemical reaction and pH distribution was carried out. The pH variations by a chemical reaction are observed by 200 ms step (i.e. 5 flames per sec). The pH image sensor was able to be applied to many application fields such as a biomedical and biochemical field. The technique of this pH sensor is based on the principle of a charge-coupled-device (CCD). The ion-sensing region is the thin Si3N4 film that acts as an ion-sensitive membrane. The images were taken by 200 ms step (i.e. 5 flames per sec). we tried to observe a living related material. Integrated techniques for the RF transmitter and power supply circuits by CMOS compatible and MES processes have been successfully developed for ideal smart sensing chips. The signal emission was confirmed near a few m distance. The integrated RF induced power supply system with a large capacitor of Surface Mount Devices (SMDs) is also developed. By these research results, smart micro sennsing chips could be realized.

      11:00 AM - *B4.2

      Integration of Nanostructures with Microsystems

      Liwei  Lin1.

      Show Abstract

      In the past decades, the application of microelectronic and micro/nanotechnologies to the fabrication of solid-state devices stimulated emerging research in micro/nano sensors and actuators. The versatility of semiconductor and micro/nano materials promise new systems with better capabilities and improved performance-to-cost ratio over those of conventionally machined devices. In recent development of nano devices, one key bottleneck has been the integration of nanostructures with Microsystems/CMOS circuitry. This talk will discuss state-of-art integration methodologies of nanostructures with Microsystems/CMOS with past and on-going efforts. These research results cover various issues in the synthesis and assembly of one- and two-dimensional nanostructures and heterogeneous integration using MEMS as the building blocks including synthesis and assembly of carbon nanotubes, silicon nanowires, graphene and zinc oxide nanowires. One common innovation in these projects is the use of localized heating and synthesis such that nanostructures can be grown in a room temperature chamber. Synthesis, directional growth and self-assembly of one-dimensional nanostructures with Microsystems have been demonstrated by means of localized resistive heating, inductive heating; and local electrical field directed, in-situ monitored self-assembly processes. Current research programs will be briefed in the following areas: integrated nanoelectromechanical systems using nanotubes, nanowires, graphene and electrospun nanofibers. This talk will conclude with discussions on future research directions.

      11:30 AM - B4.3

      High Sensitive Dual-gate SOI Based Ion-sensitive Field-effect Transistor beyond Nernst Limit of 59 mV/pH for Biosensor Application

      Hyun-June  Jang1, Won-Ju  Cho1, Jin Yong  Oh2, Saif  Islam2.

      Show Abstract

      Silicon based bio-chemical sensors such as electrolyte-insulator semiconductor (EIS) and ion-sensitive field effect transistor (ISFET) have become increasingly important subjects of research due to their potential; compatibility with state-of-the-art complementary metal–oxide–semiconductor (CMOS) manufacturing technologies, disposability and label free sensing of biomolecules. Bio-chemical sensor based on ISFETs, however, simultaneously exhibited a main weakness in terms of device instability caused by ionic damages for long-term usage. Also, the poor sensing margin of ISFETs, theoretical maximum value is 59 mV/pH based on Nernst equation at room temperature, has highlighted serious threats for stability and reliability of devices. In this work, we realized high sensitive dual-gate (DG) ion-sensitive field-effect transistors (ISFETs) beyond Nernst limit of 59 mV/pH using silicon-on insulator (SOI) substrate. The electrical characteristics of the SOI MOSFET and the sensing properties of the SOI ISFET were evaluated using single gate or dual gate operations. As a result, although a relatively low sensitivity of 43.6 mV/pH was obtained by the top gate operation, the back gate operation significantly enhanced the pH sensitivity up to 379.2 mV/pH. This is because the sensitivity of DG ISFET is modified by the capacitive coupling between top gate oxide (sensing membrane) and bottom gate (buried oxide) of silicon channel. The electrical characteristics of the SOI MOSFET and sensing properties of the SOI DG ISFET were evaluated by single or dual gate mode operations. Also, an acceptable result associated with the long-term instability of ISFETs such as hysteresis and drift was obtained from the dual-gate operational mode. Therefore, the DG SOI-ISFETs, which are compatible with CMOS process, is very promising bio-chemical sensor for bio-medical applications.

      11:45 AM - B4.4

      Nanoprobe Array for Gene Transfer into Individual Cells

      Akihiro  Goryu1, Rika  Numano1, Makoto  Ishida1, Takeshi  Kawano1.

      Show Abstract

      Gene transfer techniques including gene gun are powerful tools in physiological sciences. In advances in nanotechnology, nano-scaled penetrating probes such as AFM probe and CNT have been used for the gene transfers, providing their advantages of local and pinpoint DNA transfers into the target cells. However, further technical requirements such as multipoint/batch and deep area gene transfer techniques are still problematic. For a new class of the gene transfers, we have developed the nanoscale-tipped microprobe array with a high aspect ratio fabricated by VLS growth of silicon microprobe, followed by the silicon chemical etching-based nanotip formation. The length and diameter of the probe-body were set at 20 μm and 2 μm, respectively, and the radius of curvature of the probe-tip was set at less than 100 nm. Individual nanoprobes were spaced 100 μm apart. For the multipoint DNA trap, these nanoprobes were metalized with 100 nm-thick gold by sputtering, and encapsulated with 1μm-thick parylene excepting for the gold-tip sections. After fabricating the nanoprobe device, we demonstrated DNA transfers into cells. The procedure comprise three major steps: (i) cells are cultured for 2-3 days, (ii) after dropping a solution including DNA onto the cultured cells, nanoprobes are penetrated into the cells for transferring DNA. (iii) on the next day, the cells are observed by fluorescence microscope. All cells presented were HEK293 and we used YFP (2μg/μl) by ubiquitous promoter. DNA transferred cells were observed by the fluorescence positive response during the fluorescence observations (Ex= 488 nm, Em= 530 nm). We also prepared cells without the nanoprobe penetration (cells were dipped in the same DNA solution), and confirmed no DNA transferred cells. However, the yellow cells were clearly observed by using the nanoprobe penetration, indicating that DNA was transferred into individual cells. In addition, another advantage of the nanoprobe array-based DNA transfer was confirmed as multipoint DNA transfer into individual cells at the same time. Such nanoprobe array-based DNA transfers are simple, fast and reproducible. Additionally, deep area DNA transfers would be possible by using the nanoprobe with a high aspect ratio, promising multipoint, local, and deep area gene transfers as a powerful experimental tool in numerous biological experiments.

      B5: Bio II

      • Chair: Albert Pisano
      • Thursday PM, April 12, 2012
      • Moscone West, Level 2, Room 2000
       

      1:30 PM - *B5.1

      MEMS on LSI by Adhesive Bonding and Wafer Level Packaging

      Masayoshi  Esashi1, Shuji  Tanaka2.

      Show Abstract

      MEMS (Micro Electro Mechanical Systems) as switches and filters fabricated on LSI are required for multi-band wireless systems, in which good mechanical properties are required for the MEMS and small feature size for the LSI. Such MEMS on LSI can be implemented by following three methods. The first method is a surface micromachining and AlN Lamb wave resonators are fabricated for on-chip multi-frequency oscillators. The second method is a MEMS fabrication after wafer adhesive bonding on a LSI wafer. MEMS micromechanical resonators and FBAR (Film Bulk Acoustic Resonator) are fabricated using AlN. The third method is a bonding of MEMS wafer to LSI wafer. SAW (Surface Acoustic Wave) filter is fabricated on a LSI. This method does not require the damage-free MEMS fabrication to LSI, however the density of MEMS is limited and stray capacitance is increased because of the bonding pads. The MEMS should be encapsulated on a wafer because the moving MEMS are damaged by a direct plastic molding. Wafer level packaging has been developed for this purpose. LTCC (Low Temperature Co-fired Ceramics) which have electrical feedthrough for interconnections has been developed. Owing to the matched thermal expansion of the LTCC with that of the Si the LTCC can be anodically bonded to the MEMS-on-Si wafer for the purpose of the wafer level packaging.

      2:00 PM - *B5.2

      Integrated Circuit and MEMS Self Powering Applications Based on Organic Polymer Solar Cells and Hybrid Polymer Super-Capacitors

      Bernard  Courtois2, Clinton  K  Landrock1, Gregory  Di Pendina2, Badr  Omrane3, Jeydmer  Aristizabal3, Bozena  Kaminska3 1.

      Show Abstract

      Integrated Circuits and MEMS self powering needs are currently growing. For ultra low power devices and embedded applications that require ultra-lightweight systems with small footprints and autonomous operation, the primary energy source is typically a battery, that is substantially larger than the system it powers. The thin, flexible and low cost nature of polymer electronics can enable electronic integration, with no system area overhead, where more expensive, rigid and brittle silicon-based counterparts are no longer compatible. In this work we present recent advancements in the development of ultra-stable polymer solar cells (PSCs) and ionic-polymer based hybrid energy storage (PES) devices capable of storing harvested solar energy in a low cost thin-film stack. Such a solution offers novel areas of flexibility in terms of voltage configuration and packaging for instance. The design, architecture and fabrication of a fully integrated energy harvesting system for powering integrated circuits is discussed and demonstrated.

      2:30 PM - B5.3

      Fabrication of Bio-MEMS Device for on-chip Testing of the Bacteria Behavior

      Youngshik  Shin1, Kyohei  Katsube1, Kazuaki  Sawada1, Makoto  Ishida1, Hiromu  Ishii1, Katsuyuki  Machida2 3, Kazuya  Masu2, Ken-ichiro  Iida4, Mistumasa  Saito4, Shin-ichi  Yoshida4.

      Show Abstract

      Recently, bacterial infections have become a serious social problem, such as an outbreak of E.-coli.-O104 infection in Europe this year. To avoid such outbreak or to find methods for treatment, the knowledge about bacterial behavior is very important. To investigate the nature of bacteria, series of trial and error testing varying experimental conditions such as temperatures, pH, etc. in vitro have been performed. These experiments take time and many efforts of researchers. The device that enables us to know the nature and the behavior of bacteria at a time is desired. Applying micro-fluidic channels and chambers made with Bio-Micro-Electro-Mechanical Systems (Bio-MEMS) has successfully shown to be effective way to observe the structural-dependent behavior of bacteria such as E.-coli. [1]. Bio-MEMS devices having functions for controlling the chamber conditions on a chip are further expected for observing bacterial behavior. We propose a Bio-MEMS device having the micro chambers that operate as test tubes, by which we can observe bacterial behavior under various conditions at a time on a chip. When the bacteria are inserted into the inlet chamber that is connected to the micro chambers through micro-fluidic channels, we can recognize which conditions bacteria favor by observing which chamber they head for. This work mainly focuses on the fabrication of the chip for observing the temperature-dependent behavior of bacteria, as a prototype of such Bio-MEMS devices. The chip of the device consists of two stacked Si layers. The upper layer of the chip has five chambers: The one is for the inlet of the bacteria and the other four are the target chambers for bacteria, which are placed around the inlet chamber via micro-fluidic channels. The chambers and channels are filled with liquid in which bacteria move by sensing temperature gradient between the inlet and target chambers. The lower layer of the chip has heaters to independently raise the temperature of four target chambers. The upper and lower layers were fabricated separately using 4-inch Si wafers. Protecting fragile MEMS portions such as micro fluidic channels from damages during the fabrication is the key to obtaining the desired device. So, we used the wafer bonding and laser dicing after completing the fabrication processes for each wafer. The structures of the upper layer were fabricated with MEMS processes; a double-sided lithography and a deep reactive ion etching. The resistive heaters of the lower layer were made with poly-Si. Each wafer was bonded together with adhesive fluoropolymer. Then, the laser dicing, or stealth dicing cut the bonded wafer into chips. This completed the fabrication process. Our device enables us to investigate the nature of bacteria under various temperatures. Thus, on-chip testing by the Bio-MEMS device paves the way for investigating the bacterial behavior. [1] Jaan Mannik et al., PNAS, Vol. 106, No. 35, pp. 14861-14866 (2009).

      2:45 PM - B5.4

      An Optimized ICP Etching Process of V-Grooves in GaAs for Pyramidal C-QWIP FPAs

      Jason  Sun1, Kwong-Kit  Choi1.

      Show Abstract

      ABSTRACT We developed an optimized inductively coupled plasma (ICP) etching process of V-grooves in GaAs. A statistically-designed experiment was performed to optimize the etching parameters. The resulting parameters are discussed in terms of the effect on the etching rate and profile. This process uses a small amount of mask corrosion and the control of the etching mask gap to give a 45-50 degree V-groove etching profile, which is independent on the crystal orientation of GaAs. The relationship between the gap width and the etching profile, the etching rate is also discussed. In the etching development, scanning electron microscope (SEM) and atomic force microscope (AFM) were used to observe the surface morphology and the pattern profile. In addition, X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) were utilized to obtain the elemental composition, the contamination, and the damage in the top 10nm of the etching surface. It is found that extremely small stoichiometric change and surface damage of the etching surface can be achieved while keeping relatively high etching rate and ~45 degree V-groove etching profile. This etching process is applied to the fabrication of pyramidal corrugated quantum well infrared photodetector focal plane arrays, which is expected to have better performance than the regular prism-shaped C-QWIPs. The expected results will be verified by optical and electrical measurements. In addition to infrared detectors, this process technology can also be applied to GaAs V-groove solar cell, quantum wire light-emitting diodes, quantum wire lasers, and other GaAs–based devices.

      3:00 PM -

      BREAK

      Show Abstract

      B6: Package

      • Chair: Benoit Charlot
      • Thursday PM, April 12, 2012
      • Moscone West, Level 2, Room 2000
       

      3:30 PM - *B6.1

      Heterogeneous Integration over Scale, Material and Process

      Hiroyuki  Fujita1, Hiroshi  Toshiyoshi1.

      Show Abstract

      The technological revolution is essential for innovation. With the saturation in miniaturization of microelectronics as well as the maturity of MEMS, now the heterogeneous integration technology combining various fabrication methods is required. We can utilize micromachining, VLSI (very large scale integration) silicon microelectronic technology, compound semi-conductor technology, nano technology, bio technology, organic/inorganic chemistry, printing and molding to create a versatile manufacturing technology. Each technology offers the capability to realize specific functionality in different scales with different materials. This talk deals with the concept towards the heterogeneous integration of devices and functionality into micro/nano systems and the current development trend. The heterogeneous integration technology includes three features: (1) Hetero-scale integration from nanometer to meter scale, (2) Hetero-material integration from bio and organic materials to semiconductors, (3) Hetero-process integration of bottom-up and top-down processes. I will discuss those features, using the examples from my own laboratory and a Government-supported project named BEANS.

      4:00 PM - *B6.2

      MEMS Digital Micro Shutter Technology Leverages Existing LCD Fabrication Capability for Low-power Transflective Displays

      J. Lodewyk  Steyn1, Timothy  Brosnihan1, John  Fijol1, Jignesh  Gandhi1, Nesbitt  Hagood1, Steve  Lewis1, Richard  Payne1, Joyce  H  Wu1.

      Show Abstract

      The Pixtronix Digital Micro Shutter (DMS™) display technology provides the lowest power consumption at the best image quality for all mobile multimedia applications. This technology is based on MEMS micro-shutters formed on active TFT backplanes. These MEMS shuttering devices have enabled the development of color sequential, time division gray scale, direct-view displays achieving wide color gamut, high brightness, high contrast ratio and wide view angles, all at roughly ¼ the power consumption of competing TFT-LCD or AMOLED displays of the same size and luminance. This paper explores the design, performance and reliability of the enabling MEMS shuttering element. Features of the design are detailed as they relate to robust performance and manufacture. Pixtronix displays are shown to be manufacturable in existing LCD fabrication lines, significantly reducing time to market and increasing profitability.

      4:30 PM - B6.3

      Graphene-based Composites as Efficient Thermal Interface Materials

      Khan  M F  Shahil1, Alexander  A  Balandin1 2.

      Show Abstract

      Continuous scaling of electronic devices and circuits, increased speed and integration densities resulted in problems with thermal management of advanced computer chips [1]. Further progress in information, communication and energy storage technologies requires more efficient heat removal methods and stimulates the search for thermal interface material (TIMs) with enhanced thermal conductivity. The commonly used TIMs are based on polymers or greases filled with the thermally conductive particles such as silver or silica. The conventional TIMs require high volume fractions of the filler material (up to ~70%) to achieve thermal conductivity of about 1–5 W/mK of the composite. Recently, some of us discovered that graphene has extremely high intrinsic thermal conductivity, which exceeds that of CNTs [2-4]. To utilize this property for thermal management applications, we used the inexpensive liquid-phase exfoliated graphene and few-layer graphene (FLG) as filler materials in TIMs. The thermal properties of the obtained graphene-epoxy composites were measured using the “laser flash” technique. It was found that the thermal conductivity enhancement factor exceeded ~ 2300% at 10% of the graphene/FLG volume loading fraction. This enhancement is larger than anything that has been achieved with other filler materials. The physics-based modeling analysis of thermal properties of TIM composites suggests that graphene can outperform other carbon allotropes and derivatives as the filler. Graphene-based TIMs have a number of other advantages related to their viscosity and adhesion, which meet the industry requirements. Our results suggest that graphene can become excellent filler materials in the next generation of TIMs for the electronic, optoelectronic and photovoltaic solar cell applications [5]. The work in Balandin group was supported, in part, by the SRC – DARPA through FCRP Functional Engineered Nano Architectonics (FENA) center and the Winston Chung Global Energy center at UCR. [1] A. A. Balandin, Chill Out: New Materials and Designs Can Keep Chips Cool, IEEE Spectrum, 29, 35 (2009). [2] A. A. Balandin, S. Ghosh, W. Bao, I. Calizo, D. Teweldebrhan, F. Miao&C. N. Lau, Superior Thermal Conductivity of Single-Layer Graphene, Nano Lett. 8, 3, 902 (2008). [3] S. Ghosh, W. Bao, D. L. Nika, S. Subrina, E. P. Pokatilov, C. N. Lau,&A. A. Balandin, Dimensional crossover of thermal transport in few-layer graphene, Nature Mat., 9, 555 (2010). [4] A. A. Balandin, Thermal properties of graphene and nanostructured carbon materials, Nature Mat., 10, 569 (2011). [5] For details visit Balandin group web-site: http://ndl.ee.ucr.edu

      4:45 PM - B6.4

      A 3-dB Quadrature WLP Coupler for 60 GHz Applications

      Hamid  Kiumarsi1, Hiroyuki  Ito1, Noboru  Ishihara1, Kenichi  Okada1, Yusuke  Uemichi2, Yasuto  Chiba2, Kazuya  Masu1.

      Show Abstract

      The increasingly highly doped, conductive substrates resulting in lossy on-chip passive components is one of the main drawbacks of standard CMOS processes which worsens with moving toward higher frequencies like 60 GHz. Realizing of an on-chip 3-dB quadrature coupler at 60 GHz is impractical due to its large size and hence high loss, though it's a key component in various circuits such as balanced amplifiers and balanced mixers. In this paper for overcoming the problem, we have used WLP (Wafer Level Packaging) technology and proposed a new tandem coupler using offset broadside coupled lines for power combining in 60 GHz band. WLP technology is a promising way for cost saving and integration of high quality passive components with active circuits. Our developed WLP technology has three layers of metal, namely, ground, 1st metal and 2nd metal. Considering that the minimum allowed line space and line width is 15 um and the height of the 2nd metal from the ground is 20 um, some standard 3-dB coupler structures like broadside coupled-line coupler was not a suitable choice for our WLP process. The designed coupler occupies an area of 0.288 square millimeter, has simulated maximum insertion loss of 0.62 dB, a return loss of better than 30 dB, a phase unbalance of better than 0.35 degrees, a gain unbalance of better than 0.09 dB and an isolation better than 35 dB from 57 GHz to 66 GHz. Measured results will be presented in the full paper.

      B7: Poster Session

      • Chair: Kazuya Masu
      • Thursday PM, April 12, 2012
      • Marriott, Yerba Buena, Salons 8-9
       

      8:00 PM - B7.1

      Integrated RF MEMS Switches/CMOS Devices with Novel Fast Charging/Discharging Ultrananocrystalline Diamond (UNCD) Dielectric Layer

      Orlando  Auciello1, Charles  Goldsmith2, Anirudha  V  Sumant3, Suresh  Sampath4, Srinath  Balachandra4, Christopher  Gudeman4, James  Swonger5.

      Show Abstract

      Radio frequency RF MEMS systems have many benefits over conventional semiconductor devices for controlling and routing microwave and millimeter-wave signals. RF MEMS switches exhibit very low insertion loss and power consumption, and ultrahigh linearity, which enable high efficiency phase shifters or tunable filters for mobile communication and radar systems. Reliability inhibited deployment of RF MEMS switches in military or commercial systems, mainly due to failure related to electrical charging of the dielectric layer on top of the bottom electrode. Proposed solutions to charging include hermetic packaging, minimizing the electric field across the dielectric, and tailoring the polarity and waveform of bias control signals. These approaches provided improvements in reliability, but did not eliminate RF MEMS switch failure due to fast electrical charging (10s of µsec) and slow discharging (100’s of sec) of the oxide or nitride dielectric layers used in RF MEMS capacitive switches. This presentation shows that a novel ultrananocrystalline (UNCD) diamond film dielectric layer with 2-5 nm grains and 0.4 nm wide grain boundaries exhibit unique fast charging (~ 100 µsec) but also fast discharging (~ 100 µsec) behavior, the latter being 5-6 orders of magnitude faster than the discharging of oxide and nitride dielectric layers. Thus, the UNCD dielectric layer eliminates RF MEMS switch charging-induced failure, due to fast charge motion in and out of nanograins though atomic wide grain boundaries. The switch pulls down charging the dielectric layer to failure, but the latter discharges quickly when the voltage is removed. Thus, the switch always recovers fully from charging before the next switch operation, providing for the first time an operating RF MEMS switch continuously “on” without adverse impact on switch reliability. The results presented here demonstrate a new paradigm in RF MEMS switch operation with no dielectric charging failure. The paper will describe the first demonstration of monolithically integrated RF MEMS switches/CMOS devices with the CMOS devices driving the RF MEMS switch to billion of cycles.

      8:00 PM - B7.2

      A Study on Integration of MEMS and CMOS with Applying Flip-chip Assembly in Wireless Applications

      Atsushi  Shirane1, Hiroyuki  Ito1, Noboru  Ishihara1, Kazuya  Masu1.

      Show Abstract

      Heterogeneous integration or More Than Moore is rapidly drawing interest as a new research field. This work focuses on applying the technology of the heterogeneous integration to wireless transceiver circuits. The assembling effect of different devices such as CMOS and MEMS (Micro Electro Mechanical Systems) on wireless transceiver circuits is a key issue, and was evaluated in this paper. Then, measurement results were compared with the simulation results. By realizing passive elements such as inductors in wireless transceiver circuit with MEMS process, these passive elements can obtain the tunable characteristic and high Q-factor, which is not possible to realize using only CMOS process. As a means of integrating MEMS and CMOS devices, flip-chip is very attractive because of its small footprint and short bump interconnect. In the flip-chip, However, MEMS and CMOS chip are implemented in a manner where both devices are facing each other. Thus, there is concern about degradation in Q-factor, altering the values of the passive elements and the added noise by capacitive and inductive coupling from various parts of wireless transceiver. In this work, by applying flip-chip bonding to MEMS and CMOS chip, the changes of the inductance and the Q-factor of the inductor built on MEMS was measured before and after the implementation. Also, the effect of the coupled noise from the clock which is used in the control circuit of MEMS was observed. By comparing the measured results with 3D electromagnetic simulation and circuit simulation results, the issues which are missed in the design stage were cleared for the establishment of the integrated design methodology for heterogeneous integration, which is the ultimate goal.

      8:00 PM - B7.3

      Failure Analysis of Insulated-gate Bipolar Transistors with 3D X-Ray Microscopy and SEM

      Jeff  Gelb1, Yasunori  Goto2.

      Show Abstract

      Today’s most advanced electronic devices demand powerful technology to support them. Insulated gate bipolar transistors (IGBTs) are one potential solution to address these needs, owing to their fast switching and high efficiency, producing advantages for complex amplifiers with low pass filters and pulse width modulation. In order to support the development of IGBT devices, however, an appropriate characterization method is needed. While many 2D techniques have been established, these techniques are generally limited to surface examinations. When these devices fail, however, the damage occurs in three dimensions. X-ray microscopy is now an established technique for 3D failure analysis and microstructure characterization, due to the high penetration power of x-rays. Their non-destructive nature enables precise characterization of internal features without physically destroying the sample, enabling repeated studies on one sample to examine, for example, the time evolution of damage propagation. Commercially-available microscopes are now capable of producing resolutions in the tens of nanometers, delivering similar characterization capabilities as electron microscopes, but without sectioning the sample and with no charging effect. In the study presented here, one IGBT device was purposely damaged by an avalanche test between the polysilicon trench gates and prepared with FIB to an appropriate size for imaging with ultra-high resolution x-ray microscopy. The surface defects were first examined by scanning-electron microscopy and subsequently imaged in 3D with a commercial nano-scale x-ray microscopy platform. While the SEM results clearly showed some damage between the polysilicon trench gates, the x-ray results revealed a complex damage structure in 3D. Further analysis revealed the precise nature of the damage, enabling a more comprehensive characterization of the IGBT device than has previously been possible.

      8:00 PM - B7.4

      Collagen as Dielectric Humidity Sensing Material

      Mathew  A  Hudspeth1, Tolga  Kaya1 2.

      Show Abstract

      The motivating principle behind this research is the development of a small, wearable sensor that would use humidity and temperature measurements as metrics for health monitoring. If it is to be useful as a health monitoring tool, the device needs to respond quickly and predictably to changes in humidity. Also important is keeping the cost of the materials low. In this work, collagen is shown to be a viable humidity sensing material for use in capacitive relative humidity (RH) sensors. As a natural by-product of meat and leather industries, collagen presents itself as an interesting and inexpensive alternative to polyimide dielectric sensing materials. We used gelatin, a partially hydrolyzed form of collagen, to allow for easier thin film deposition. We have successfully fabricated devices by depositing a collagen thin film (15 μm) via spin coating, followed by Au/Pd electrodes (60 nm) via sputter coating. A plastic mask made with a rapid prototyping machine was used during physical vapor deposition (PVD) to pattern electrodes. This simple method eliminates the need to use more complicated photolithography processing. Interdigitated electrodes, rather than parallel plate electrodes, form a 6 mm wide, planar capacitor that has little dependence on dielectric thickness and is not affected by dielectric swelling. Characterization methods include rapid humidity change to evaluate response, steady-state measurements to evaluate consistency and obtain capacitance-humidity relationships, temperature modulation, and scanning electron microscopy (SEM). Initial findings indicate that these devices very closely match the results of the commercial relative humidity sensor (Omega OM-73) used for reference. The capacitance-humidity relationship is shown to be non-linear, with an average change of 3.0 fF for every 1% change in RH around 60% RH, and an average change of 7.0 fF for every 1% change in RH around 80% RH. In this work, we present the fabrication and characterization of these novel collagen-based relative humidity sensors.

      8:00 PM - B7.5

      Vibration Analysis of Coupled Vertical Resonators for Acceleration Sensitivity Reduction of out-of-plane Vibratory Gyroscopes

      Praveen  Thakur  Singh1, Koji  Sugano1, Toshiyuki  Tsuchiya1, Osamu  Tabata1.

      Show Abstract

      The frequency responses of coupled vertically oscillating resonators are simulated and measured to investigate the source of acceleration sensitivity in out-of-plane vibratory MEMS gyroscopes. The acceleration sensitivity in MEMS gyroscopes is one of the important issues, since the gyroscopes are often used in harsh conditions in terms of vibration, especially for automobile application. The tuning fork type gyroscopes (TFG), in which two coupled vibratory gyroscopes are operated anti-phase manner, is the best solution for eliminating acceleration output by differentiating two outputs. However, the unbalanced mass and stiffness of springs from fabrication imperfection are said to be the source of the acceleration output which still exists in TFGs. We have investigated the mechanism how in-phase acceleration causes anti-phase vibration appeared as angular-rate output in in-plane TFG in the previous works and proposed the way to reduce the acceleration output by decoupling the in-phase (fin) and anti-phase (fanti) modes of the sensing vibrations. In this paper, the out-of-plane gyroscopes with out-of-plane resonators for sensing are being investigated. To simplify our analysis, instead of fully operating out-of-plane gyroscope, we designed four types of vertically coupled resonators by changing coupling scheme, coupling spring and coupling frame, and resonator, linear vibration and torsional vibartion. Each type of coupled resonator is designed with decoupling of in- and anti-phase mode (decoupling ratio, DR= (fanti-fin)/(fanti)) values of 0.09, 0.13 and 0.29. We fixed the anti-phase frequency at 16.5kHz and shifted in-phase frequency. In all designs, resonator proof-mass size is same. The designs were fabricated on SOG process of 20µm thick. In experimental evaluation, the devices were placed on piezo-actuator in vacuum chamber for applying vertical mechanical excitation with a frequency sweep in the range of 0-20kHz and observed under scanning laser Doppler Vibrometer. We maintained the vacuum about 20Pa. The results of all devices showed that at anti-phase frequency, two resonators are excited in anti-phase mode and as decoupling ratio increases from 0.09 to 0.29, resonators anti-phase mode excitation amplitude decreases by one-eight.

      8:00 PM - B7.6

      Dual Spiral-shaped Micro Viscosity Sensor

      Yasuyuki  Yamamoto1, Sohei  Matsumoto3, Hiroshi  Yabuno2, Masaharu  Kuroda3, Kenichi  Fujii1, Tomoko  Yamamoto3.

      Show Abstract

      This paper reports a MEMS based vibrating viscometer suitable for in-process measurement in industrial fluid plants and low-cost disposable uses for medicine. Vibrating body of the proposed sensor is unique dual spiral geometry. The geometry provides a seamless surface for sensing the viscous stress by the simple structure to assemble the parallel plates to create the Couette flow into the MEMS device. The principle of the viscosity measurement based on the proposed dual spiral geometry was successfully verified by the experimental results using the first prototype devices. In the prototype viscosity sensor, the spiral structure is formed by penetrating trenches of 40 micro meters width on Si wafer of 500 micro meters thickness. The trenches were shaped by Deep-RIE. The width of the spiral wall is 80 micro meters. The dual spiral is composed of the two independent spirals. One spiral is named vibrating spiral which is vibrated by a piezo actuator and another spiral is called sensing spiral which is driven by viscous stress. The sensor chip is mounted in a holder included a piezo actuator and a pin to push the center of the vibrating spiral. In experiment, the whole holder is dipped in a liquid. As the piezo actuator is activated, the vibrating spiral is deformed and the viscous stress is developed in the liquid in the gap. The sensing spiral is deformed by the viscous stress. Frequency response curve of sensing spiral is calculated by analyzing the equation of motion. Our theory differs from the popular vibrating viscometer in that the external force which acts on the sensing body is only the viscous force. The viscosity of the liquid is obtained by curve fitting of the frequency response. Because the prototype sensor dose not have integrated strain gauges to measure the displacement of the spirals, a testing system which has a laser displacement sensor was built to examine the measurement principle. Sample liquids are Japanese standard reference liquids. Experimental results of the frequency response are collected. Parameter of the sensor is calibrated using the fitting value of the JS10 one of the reference liquid. By using the fitting value of the others, measurement values of the viscosity are calculated. The measurement results and deviations agree with the reference values less than 10 %. Although the deviations of the values are not sufficiently small, the experiment verified that the proposed dual spiral-shaped structure can be applied to the viscosity measurement.

      8:00 PM - B7.7

      Drop-coating Silanization of Silicon Substrates as a Step towards the Fabrication of CMOS-based MEMS Biosensors

      R.  Pilolli1, N.  Ucciferri2, V.  Russino3, Nicola  Cioffi1, N.  Ditaranto1, C.  Domenici2, A.  Nannini3, F.  Pieri3, L.  Tedeschi2.

      Show Abstract

      MEMS-based biosensors are a promising new platform for the delivery of diagnostic services close to the point of care, where issues like reliability, ease of use, and low cost are of primary importance [1]. The intrinsically parallel nature of MEMS fabrication allows for very low unitary cost of elementary MEMS components. As an added benefit, the reuse or modification of standard Complementary MOS (CMOS) technologies allows the coexistence on the same silicon chip of MEMS components and the driving and conditioning circuitry. In the case of biosensors, specific issues related to the bio-activation of the sensor surface and its compatibility with on-chip MEMS and electronics have to be taken into account [2]. While standard bio-functionalization procedures normally involve immersion of the sample in the required solutions, this approach may not be feasible for silicon chips containing mechanically sensitive MEMS components and electronic circuits. Moreover, the bio-coating technique must be compatible with sensor package and wiring. In this work, the use of drop-coating [3] as a substitute to immersion for the creation of bioactive surfaces on MEMS sensors is investigated. The target sensor platform is a CMOS-based resonant sensor based on the microbalance principle [4]. Preliminarily, a test to verify the effectiveness of the functionalization protocol was performed: test silicon dioxide surfaces were cleaned in an ammonia-based hydroxylation solution, and silanized through drop-coating with an aqueous-based APTES (amino-propyl-triethoxysilane) solution as the preliminary step towards the deposition of a bioactive layer [5]. The surfaces were studied by means of conventional and angle resolved x-ray photoelectron spectroscopy. The spectroscopic characterization confirmed that the resulting surface chemical composition was not significantly different upon the two alternative processing approaches: both the atomic percentages values and the outermost layer in-depth distribution of the functionalities are comparable for the two approaches. Subsequently, a sample containing several MEMS resonators [4] underwent a similar procedure. The amino coated resonators were then exposed to a solution containing an oligonucleotide specifically designed to link to a portion of human MGMT (methylguanine-DNA methyltransferase) mRNA [6], and subsequently to its FITC fluorescent labeled complementary target. A comparison between this sample and a reference sample, not exposed to the target, shows a clear fluorescence signal and can interpreted as the occurrence of a specific binding between probe and target. References 1 H.-H. Tsai et al, Sens. Act. B: Chem. 144 (2010) 407–412. 2 A.C.R. Grayson et al., Proc. IEEE 92 (2004), 6-21. 3 E. Espinosa et al., Sens. Act. B: Chem. 144 (2010), 462-466. 4 D. Paci et al., Sens. Act. B: Chem. 129 (2008), 10-17. 5 S. Lenci et al., Appl. Surf. Sci. (in press). 6 L. Tedeschi et al., Biosens. Bioelectron. 20 (2005), 2376-1285.

      8:00 PM - B7.8

      Fabrication of a Capacitive Micro-mechanical Biosensor Array with Self-alignment of the Ultrathin Si Diaphragm and Laser Printing of Bioreceptors

      Stavros  Chatzandroulis1, Vassiliki  Tsouti1, Georgios  Tsekenis3, Marianeza  Chatzipetrou2, Dimitris  Thanos3, Ioanna  Zergioti2.

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      In this work we present a self-aligned process for the fabrication of round ultra-thin silicon membranes which constitute the sensing element of a 64 element micromechanical capacitive biosensor array. To fabricate the array direct bonding between a Si wafer holding the membranes and a substrate wafer is required. The operation of the sensing elements rely on the changes in membrane surface stress and its subsequent deflection upon binding events between receptors immobilized on its surface and target molecules in its vicinity. Surface stress based biosensors are of great interest as they allow label-free sensing resulting in simplified sample preparation, small size and ability for parallelization into arrays for high throughput analysis [1-2]. The process begins by first forming a 5000Å thick thermal SiO2 layer on the membrane wafer. Circular sensor cavities are then formed in the oxide using optical lithography and CHF3 anisotropic dry etching. Next, a boron ion implantation follows through the openings in the thick oxide. This step creates a highly boron doped region which subsequently forms the flexible membrane electrode of the capacitive sensing element after wet etching. The whole procedure, effectively, aligns the sensor membrane placing it over the sensor cavity in which it is allowed to deflect. The ion implantation and annealing conditions determine the thickness of the final membranes and these conditions are selected based on simulation results and wet etching test experiments. The chosen conditions were 2E16 ions/cm2 at 150 keV, followed by thermal annealing at 1050 C for 1h. Next, the membrane wafer is bonded with the substrate wafer which has gone through phosphor implantation (1E15 ions/cm2, 20keV) followed by thermal annealing (1000 C, 20min) to render it conductive and form the sensor fixed substrate electrode. The wafer stack is then grinded mechanically, from the membrane wafer side, down to about 50µm while the rest of the wafer is etched in EDP solution until the ultra-thin Si membranes are revealed. The process then goes on with Al metallization and low temperature oxide (LTO) to passivate and finalize the device. To test the array performance 15mer synthesized thiol-modified oligonucleotide probes and corresponding targets were used. In order to immobilize the probes on the arrays, they were first functionalized with 3-glycidoxypropyl-tri-methoxy silane (GOPTS). Selective spotting of the probes on each membrane was then performed using the Laser Induced Forward Transfer (LIFT) technique. The hybridization procedure was monitored using a specially designed setup [3]. First experimental results indicate that the sensors are able to detect the hybridization of 10mM synthesized 15mer oligos. [1] J. Fritz, Analyst 133 (2008) 855–863. [2] A. Boisen and T. Thundat, Materials today, 12 (2009) 32-38. [3] V. Tsouti et.al , Biosens. Bioelectron. 26 (2010) 1588-1592.

      8:00 PM - B7.9

      Hybrid Penetrating- and Planer-Microelectrode Arrays for Simultaneous Recording of Ecog and Intracortical Neuronal Activity

      Tatsuya  Imashioya1, Akifumi  Fujishiro1, Hirohito  Sawahata2, Haruo  Toda2, Akihito  Ikedo1, Makoto  Ishida1, Isao  Hasegawa2, Takeshi  Kawano1.

      Show Abstract

      Brain-machine-interfaces (BMI) use neuronal activities of spike and local field potential (LFP) with a high spatiotemporal resolution, in order to control of artificial machines such as robot-hand/prosthetics. However, the recording of spike/LFP with penetrating-probes into a tissue induces damage to brain/neurons, while the recording of electrocorticogram (ECoG) with planer-electrode onto brain surface has the advantage of the non-invasive measurement. To determine the electrode type in the future BMI, a further analysis of data correlation between the non-invasively recorded ECoG and the invasively recorded spike/LFP is necessary. One possible approach to analyzing the correlation is simultaneous recordings of ECoG and spike/LFP with a high spatial resolution. Here we propose a hybrid integration of ECoG recording- and spike/LFP recording-electrode arrays. We designed and fabricated ECoG and spike detecting hybrid-neuroprobe devices, based on a single-chip integrated IC-processed planer-microelectrodes and vapor-liquid-solid (VLS) grown penetrating-microprobes. The length of the probe was set at 200 µm, making the I-II cell layers of a cortex possible to reach. Diameters of the probe-tip and the planer-electrode were set at 1 μm and 20 μm, respectively, and individual electrodes were spaced 100 µm apart. After packaging the device, each recording site of the array was metalized with a low impedance material of Pt-black by the electroplating. The Pt-black tipped probe resulted in low enough impedance for spike/LFP and ECoG recordings. In order to demonstrate simultaneous recordings of ECoG and spike/LFP, the fabricated hybrid-neuroprobe device was placed on the visual cortex of a Long–Evans rat. A display monitor was placed in front of the rat, and we used computer controlled visual stimuli via the display. We confirmed the ECoG and spike/LFP recording capability of the hybrid neuroprobe device, as visually evoked ECoG and spike/LFP signals were simultaneously obtained via planer- and penetrating-microelectrode arrays. Based on the design of the prototype device, further high density and/or multi-channel ECoG and spike/LFP will be obtained to reveal correlation of ECoG and spike, mechanism of nervous system, as well as to develop a new class of neural recording methodologies for the future BMI technology.

      8:00 PM - B7.10

      Electrical Immunodetection of the Avian Influenza A Hemagglutinin Peptide Using a Silicon Field-effect Transistor Fabricated Using a Nickel Self-aligned Silicide Process

      Yang Kyu  Park1, Min woo  Seo1, Yeon ho  Kil1, Jae yeon  Kim1, Chel jong  Choi1.

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      Electrical immunodetection of the avian influenza A (H5N1) hemagglutinin (HA) peptide, the IN peptide, with anti-HA antibody was demonstrated using a field-effect transistor (FET) with an n-type silicon (Si) channel and a nickel (Ni) self-aligned silicided source/drain that was fabricated by a conventional top-down process. Confocal fluorescence microscopy revealed that IN peptide was specifically bound to immobilized antibody on the patterned SiO2 overlaying the Si channel, confirming that the binding capability of the immobilized antibody was retained. Positively charged ions, which modulate the electrostatic field across the SiO2 layer, and which are contained in the PBS solution used in these studies, result in the accumulation of electrons in the n-type Si channel, leading to a rapid increase in the channel current. Upon introducing antigen-containing peptides into the SU-8 reservoir, the accumulated electrons caused by positively charged ions in the PBS solution are then reduced by the specific binding of negatively charged peptides to the immobilized antibody. From the time-dependent I-V measurements, the settling time required to stabilize the electrical signals caused by negatively charged antigens was estimated to be 32 s

      8:00 PM - B7.11

      Selective Surface Functionalization of Si and poly-SiGe Resonators for a Monolithic Integration of Bio- and Gas Sensors with CMOS

      Silvia  Armini1, Vladimir  Cherman1, Alexander  Volodin2, Silvia  Lenci1 3, Francesco  Pieri3, Daan  Wouters4, Joos  Moonens1, Pieter  Neutens1, Cecilia  Dupre5, Eric  Ollier5, Yoshishige  Tsuchiya6, Hiroshi  Mizuta6.

      Show Abstract

      Resonant SOI-CMOSFET NEMS gas/bio sensors represent an important fundamental research topic and an emerging technology for many applications, thanks to the high flexibility offered by the surface functionalization methods which can tailor sensing layers for a large variety of gases and biomolecules. Self-assembled monolayers (SAMs) are one of the most relevant functionalization approaches to achieve selectivity in the sensing processes. Although the optimization of these organic films has received considerable attention, most of the functionalization routes have focused on the coating of sensors with relative large areas. The downscaling of the SAMs to small nano-devices, such as Si and poly SiGe NEMS and MEMS-based sensors, requires additional tools, both for their selective deposition and characterization. In this work, two main approaches to selective Si nanowires functionalization are being investigated: i) selective Joule heating ablation of the protective polymer layer on the suspended NW surface, and ii) e-beam lithography to open the resist layer on the NW area. In a following step, a NH2-SAM layer is deposited on the unprotected silicon oxide surface and glutaraldehyde molecules are used as a linker between the SAM amino functionality and biotin. The frequency shift response during CO2 sensing is studied as a function of an increasing number of amino functionalities of the silanization precursors. Finally Kelvin probe atomic force microscopy allows mapping the functionalized area due to the observed shift in surface potential between bare and SAMs-coated SiO2 surface.

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      B7.12 Transferred to B8.2

      Show Abstract

      8:00 PM - B7.14

      Noble Metal Deposition Using Supercritical Fluid for Embedded DRAM and FeRAM Applications

      Yukihiro  Shimogaki1, Kei  Watanabe1, Satoshi  Suita1, Takeshi  Momose1.

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      As device size of ULSI shrinks, the size of memory capacitors has been shrinking. To maintain the capacitance of memory capacitors, it is necessary that surface area of capacitors is not reduced even though capacitor projected area decreases. Thus, capacitor structure will become more complicated like as a trench features. Thus, ultra-thin and conformal capacitor electrodes will be required. Ru and Pt is one of the major candidates for electrodes of memory capacitor such as dynamic random access memories (DRAMs) or ferroelectric random access memories (FeRAMs) because Ru is a good conductor even though it is oxidized to RuO2 and Pt has good anti-oxidization property. The property of Ru and Pt as the electrodes was reported in many researches. Recently, embedded DRAMs or FeRAMs (eDRAMs or eFeRAMs) were getting much attention as one of the applications of DRAMs or FeRAMs. The eFeRAMs are put on a chip with the logic circuit in order that the size and the energy consumption of ULSIs is expected to be reduced by employing non-volatile memory. The eDRAMs or eFeRAMs are fabricated after the logic circuit. To prevent the logic circuit from thermal damage, the eDRAMs or eFeRAMs should be fabricated at low temperature. To fabricate conformal films for these devices, we applied supercritical fluid deposition (SCFD) method. In SCFD, supercritical CO2 (scCO2) is used as solvent and deposition is performed by chemical reactions of precursors in scCO2. Supercritical fluids have intermediate property of gas and liquid. The density of supercritical CO2 can approach or exceed that of liquids, and thus it can be a good solvent for organometallic compounds and their organic decomposition products. Precursor transport occurs in solution and reduction occurs at the solution/solid interface at significantly lower temperatures and higher reagent concentrations than those of vapor-phase techniques such as CVD. Thus, SCFD has the advantage of both gas-phase and liquid phase reaction. In this work, Ruthenium and Platinum thin films were deposited onto planar and trench structure SiO2/Si substrates by SCFD. To deposit Ru films, we employed H2 as the reducing agent and acetone as an additive material. Thus, continuous Ru films were obtained. In SCFD, H2 was often used as reducing agent. However, Pt films could not be deposited by H2 reduction. Then, we tried to deposit Pt films by reduction using cyclohexane. Cyclohexane may be promising reducing agent because Pt acts as auto-catalysis and promotes decomposition of cyclohexane. Reduction by cyclohexane enables to obtain continuous Pt films with carbon impurities. To remove carbon in Pt films, we employed post deposition annealing (PDA) under O2 atmosphere and obtained pure Pt films which do not contain any carbon. After PDA with O2 gas, electrical resistivity of Pt film decreases from 50 μΩ-cm to 15 μΩ-cm. The oxidation chemistry to deposit these noble metals will be also reported.

      8:00 PM - B7.15

      New Facing Targets Sputter-etching for MEMS Materials

      Yutaka  Nakamitsu1 2, Sadao  Kadokura1, Seiichi  Hata2.

      Show Abstract

      MEMS devices and technologies have been developing, and these devices are used in various fields and products now. But, in many cases, these MEMS devices are mainly composed of silicon materials, and the kind of materials used in these devices is limited. The authors think that it will be important to use functional materials such as magnetic materials and piezoelectric materials to create functional and high-performance MEMS devices. However, there are obstacles for utilization of these functional materials in these devices. One of the obstacles is difficulty of etching these materials precisely using conventional dry etching methods such as Reactive Ion Etching (RIE). Then, we will suggest the new dry etching method, new facing targets sputter-etching (NFTSE), that easily etch these materials. Sputter-etching methods with magnetic field such as magnetron had been researched widely in semiconductor field once, before RIE technology appeared. The Sputter-etching methods have the merit that they could etch various materials physically using only Ar gas as etching process gas. But the substrates and the materials etched by sputter-etching methods suffer from strong damages by attacks of high-energy particles such as Ar ions. Also, it is difficult to obtain superior etching uniformity on substrate surface across wide area without swing or rotation of magnets that form the magnet fields on substrate surface. Therefore sputter-etching methods are not used in a semiconductor field now because of these demerits. However, these demerits do not become serious problems in NFTSE, in the cases of shaping micron size 3D structures of the functional materials in fundamental research of some advanced MEMS devices. Because, the structure size is over ten-odd micrometers, so the damage from the high-energy particles affects only a restricted surface of the structure. Moreover NFTSE area is uniformity in comparison with magnetron sputter-etching owing to unique design of the magnetic field. Then, in order to confirm the performance of NFTSE method, 1 μm thickness Cu films that deposited on silicon wafer by a magnetron sputtering method were etched by NFTSE method, using 10μm pitch resist mask on the Cu films. As a result, superior perpendicular cross section of Cu films was observed by scanning electron microscope (SEM). Moreover, NFTSE method can obtain less than 10% etching uniformity across 80mm width without swing or rotation of the magnets because of unique magnetic field structure. In addition, NFTSE method has the possibility that the uniform etching area could be spread to 8 inches by optimization of the magnetic field structure. As a result, NFTSE may become one of important manufacturing technology of MEMS devices that consist of the functional materials. For these reasons, NFTSE method will support to create value added MEMS devises in near future.

      8:00 PM - B7.16

      Fabrication and Characterization of Diamond-like Carbon Thin Films with Extremely High Compressive Stress (>8~12GPa) for Advanced CMOS Strain Engineering

      Xiaolong  Ma1, Huaxiang  Yin1, Haiqiang  Zhang2, Xu  Zhang2.

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      As the gate pitch of MOSFET scaling into sub-28nm, the strain effect induced by conventional technologies declined in nanometer device’s channel. The new stress-liner material like diamond-like carbon (DLC) with higher stress was thought as one of main techniques to solve this issue. In this paper, we fabricated DLC films with extremely high compressive stress (>8~12GPa) using S-bend filtered cathodic vacuum arc (FCVA) technology and studied the process compatibility of DLC films integration with standard CMOS process. DLC’s compositional, mechanical and thermal properties were characterized using various tools such as multi-wavelength Raman spectroscopy (633nm, 532nm, 325nm), XPS, c-AFM, TEM, and TXRF. We optimized process parameters including substrate bias voltage (carbon ions energy), base pressure and filter coil current to maximize the compressive stress in deposited films with constant thickness (20nm). We firstly presented the correlations between compressive stress and G-peak dispersion extracted by multi-wavelength Raman spectra. It’s concluded that G-peak dispersion is a more insightful and reliable merit compared with ID/IG, G peak position and FWHM of G peak. The evolution of compressive stress and surface microstructure of DLC films with post deposition thermal annealing were studied by XPS and conductive-AFM. Thermal stability and stress evolution satisfy the thermal budget of BEOL. Meanwhile, metal contamination was measured by TXRF to exclude existence of deep impurities ensuring the compatibility of DLC films with CMOS process line. Finally, we studied local stress in silicon induced by DLC films after patterning into strips by UV-Raman spectroscopy and clarified the stress transfer mechanism which can provide insights about the integration of multiple strain techniques in advanced CMOS strain engineering.

      8:00 PM - B7.17

      Improving Photoresist Spray Coating on 3D Structures for Microfluidic Devices

      Shinya  Kumagai1, Naoya  Fukuda1, Hisayoshi  Tajima1, Minoru  Sasaki1.

      Show Abstract

      In microfluidic devices, dielectrophoresis (DEP) is used to transport particles (e.g., cells, DNA). Conventional DEP devices use top or bottom electrodes which functions as collection points. The DEP device structures are limited because the photolithography is developed to fabricate planer structure. Electrodes are not fabricated on the sidewall of trench in the microfluidic devices. Photolithography for 3D structures permits wide variety of the device design [1,2]. Combining the electrodes fabricated on the sidewall with the branch of the microfluidic trenches, particle separation is achieved [3]. Photolithography for 3D structure requires uniform photoresist coating. Spray coating of photoresist is one of the promising methods for the uniform coating. We are investigating spray coating of photoresist by experimental and numerical approaches [4]. It was revealed that uniformity of the resist film is degraded by the lateral gas flow along the sample surface. Here, a shield plate with an aperture was used to suppress the lateral flow for improving the uniformity of the resist film. Gas flow was numerically analyzed by solving 2D Navier-Stokes equation. Calculation area was 50mmx46mm. Gap between shield plate and sample was 5mm. Aperture was φ9mm. With the shield plate, it was found that gas flow has enhanced vertical velocity component in the aperture area. Because the resist particles are delivered by the gas flow, the resist particle can enter trench structure to a deep level. Spray coating of the photoresist onto a substrate with trench structures was carried out using the shield plate. One direction scanning was repeated to reproduce the 2D flow in the numerical analysis. After the spray coating, line and space pattern were made to be orthogonal to the trench direction. Thickness distribution of photoresist film was investigated by white light interferometry and SEM. Without the shield plate, resist film thicknesses on top and bottom of the trench were 8.28μm and 2.59μm, respectively. With the shield plate, the thicknesses on top and bottom were 3.28μm and 2.21μm, respectively. Thickness ratio of bottom to top increased from 0.31 to 0.67. Deposition area was reduced from φ36mm to φ18mm by the plate. Bump formation which is frequently found around the convex trench corner [4] was suppressed. Bump thickness decreased from 6.80μm to 3.78μm. Uniformity of the photoresist film was improved. With the angled exposure technique [5], device structures can be fabricated on the trench sidewall. This research was supported by a MEXT program for forming strategic research infrastructure for private Universities from 2008 and Scientific Research (B) (20360116). [1] H. Houjou et al., Transducers’05, 3E4.35, p.1437. [2] P. Pham et al., J. Electrostatics 65 (2007) 511. [3] Y. Kim et al., J. Micromech. Microeng. 21 (2011) 015015 [4] S. Kumagai et al., Jpn. J. Appl. Phys. 50 (2011) 106501 [5] M. Sasaki et al., IEEE Optical MEMS Nanophotonics 2009, p.75

      8:00 PM - B7.18

      Combinatorial New Facing Targets Sputtering

      Takuya  Maetani1, Naoya  Mori1, Yutaka  Nakamitsu2, Seiichi  Hata1.

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      Combinatorial sputtering is one of the useful methods that could search for optimal composition of alloy materials or new alloy materials. Combinatorial sputtering provides sample groups (library) having different compositions in a limited place. Then, the properties of the samples can be scanned in an efficient way. It was devised that a Combinatorial Arc Plasma Deposition (CAPD) method which is a new combinatorial deposition method to search for alloy materials especially amorphous alloys. This method can synthesize the samples having wide composition ranges (more than 50 atomic %). However deposition areas (sample size) are too small and film thickness is too thin for evaluation of some properties. The New Facing Targets Sputtering (NFTS) method can be applied to new co-sputtering method for combinatorial sputtering. NFTS enables us to synthesize binary/ternary composition distribution thin film and have possibility to synthesize quaternary/quinary composition distribution thin film. One of the features of this method is that, range of composition ranges could be controlled. Furthermore larger and thicker film samples could be synthesized onto a single substrate compared to CAPD. In this research, binary and ternary composition distribution metal thin films were synthesized by using NFTS onto a single 52 mm×72 mm glass substrate. After deposited, compositions of films were characterized by the energy-dispersive X-ray spectroscopy (EDX). As an example, combinations of Cu, Zr and Ti targets were used to confirm the performance of the NFTS combinatorial sputtering method. As a result, composition distributions of synthesized thin films of Cu-Zr were formed in the range of Cu content between about 40 and about 70 atomic%. The films of Cu-Zr-Ti were formed in the range of Cu content between 25 and 60 atomic%, Zr content between 10 and 25 atomic% and Ti content between 30 and 55 atomic%. NFTS co-sputtering method can easily control composition distributions and their ranges by changing the power or the distance between targets and the substrate. In a presentation, we will report power dependency of the ternary composition distribution.

      8:00 PM - B7.19

      Characterization of Direct Piezoelectric Properties of BiFeO3 Films for Vibration Energy Harvesting

      Takeshi  Yoshimura1, Katsuya  Ujimoto1, Syuichi  Murakami2, Yusaku  Kawahara1, Norifumi  Fujimura1.

      Show Abstract

      Recently, vibration energy harvesting is receiving a considerable amount of interest, because the vibration energy exists in many environments, such as mechanical vibration and human motion: it commonly goes unused. Although several methods are useful for obtaining electrical energy from vibration energy, piezoelectric materials are the most suitable because of their capability of converting applied strain energy into useful electric energy directly and the ease with which they can be integrated into a system. The basic structure of the piezoelectric vibration energy harvester is a MEMS cantilever with a seismic mass at the end. A piezoelectric thin film is deposited on the cantilever. The vibration energy is converted to electric energy by the direct transverce piezoelectric effect of the film. Therefore, the effective direct transverce piezoelectric coefficient (e31,f) is important for the piezoelectric vibration energy harvester. [1] Lead-free ferroelectric BiFeO3 is one of the promising materials for piezoelectric devices, because BiFeO3 has a huge spontaneous polarization as large as 100 μC/cm2 and high Curie temperature (TC; 850 °C). Especially, relatively low dielectric permittivity (~50) of BiFeO3 is suitable for vibration energy harvester, because the electric energy generated by the direct piezoelectric effect is inversely proportional to the dielectric permittivity. However, the direct piezoelectric property of BiFeO3 films has not been reported. In this study, the direct piezoelectric property of epitaxially grown BiFeO3 films was evaluated. Furthermore, the dependence of the crystal orientation on the direct piezoelectric property was investigated. (001) and (111) rhombohedral BiFeO3 epitaxial films were fabricated by pulsed laser deposition, and the (001) and (111) film showed rectangular hysteresis loops with a remanent polarization of 70 and 96 μC/cm2, respectively. The e31,f coefficient of the films was measured by a method based on substrate bending and collecting developed charges. Details of the measurement method were reported elsewhere.[2] The e31,f coefficients of -3.5, and -1.3 C/m2 were observed for the (001) and (111) BiFeO3 epitaxial films, respectively. It is suggested that the large direct piezoelectric response of the (001) film is caused by the effect of engineered-domain configuration. This study was supported by Industrial Technology Research Program in 2011 from New Energy and Industrial Technology Development Organization (NEDO) of Japan. [1] T. Yoshimura et al., Materials Science and Engineering, 18 092026 (2011) [2] T. Yoshimura et al., Jpn. J. Appl. Phys. 49, 021501 (2010).

      8:00 PM - B7.21

      Intermetallic Formation in PZT Films for MEMS Structures

      Kanupriya  Sharma1, Thomas  Oseroff1, Leda  Lunardi1.

      Show Abstract

      Lead zirconate titanate is a popular material for microelectromechanical systems (MEMS) applications, known for its high spontaneous polarization and dielectric constant. These electrical properties depend highly on its crystal orientation as well as the substrate used for deposition. The formation of intermetallic compounds at the interface between the functional material layer (PZT) and the electrode layer (Platinum) is shown to facilitate the growth of a certain orientation of PZT. For this study, lead zirconate titanate with the morphotropic phase boundary composition Pb(Zr0.52Ti0.48)O3 films were deposited on Pt(111)/Ti/SiO2/Si (100) substrates by chemical solution deposition. The reactions between the precursors – lead acetate trihydrate, zirconium propoxide and titanium isopropoxide during sol preparation have been analyzed to understand the factors affecting the stability and life of the prepared sol. As the annealing temperature increases from 500°C to 700°C, a change in crystal structure from amorphous to polycrystalline pervoskite was observed. The films were characterized with X-ray diffraction (XRD), optical microscopy and scanning electron microscopy. Relevant peaks in the XRD patterns were identified revealing that that (101) is the preferred orientation. While only the presence of the intermetallic-Pt3Pb has been earlier reported, in the present study other intermetallic compounds such as PtZr, TiPt8 and Ti6Pb4 have been identified. Different intermetallic compounds at the PZT/Pt interface not only affect the orientation of the overlying PZT film but also its dielectric and polarization constants widely. The conditions for the formation of these intermetallics have been established by varying deposition cycles, annealing temperature and different kinds of substrates.

      8:00 PM - B7.22

      Portable Nano-FET Biosensor Platform for Label-free Immunodetection in Human Serum

      Gun Yong  Sung1, Jong-Heon  Yang1, Ansoon  Kim1 2, Chil Seong  Ah1, Chan Woo  Park1.

      Show Abstract

      Recently the importance of point-of-care testing is growing rapidly as the demands of decreasing turn-around-time in bed-side diagnostics and upgrading medical environments in ubiquitous healthcare are growing. Biologically modified field-effect transistor (BioFET) is one of the most attractive approaches because of the on-chip integration of the sensor array, fast response, high reliability and lowcost mass production. However, the BioFETs used to detect macromolecules have been operated only in buffer solution with low salt concentrations because of the Debye screening length of blood or serum. Here we report a novel detection technique for direct label-free immunodetection of cancer markers in human serum using a Si-FET that was fabricated by conventional photolithographic processes. The proposed sensing method shows no dissociation of antigen–antibody binding as in general immunoassays, unlike the previous reports on Si-FET sensors. This method therefore overcomes the Debye length problem of immunodetection in human fluids, such as serum, that are generally encountered by FET based biosensors.1) In addition, in order to provide the microfluidics for test samples transportation to silicon chip and electrical connectivity for quantitative analysis and to use it easily to any non-skilled persons, we developed portable clinical analyzer platform, which consisted of small-size silicon-chip packaging cartridge and portable reader with easy user-interface. We demonstrate that connecting our simple electrical detection method, which does not require pretreatment of serum, with well-established whole blood filter technology will contribute to the development of new point-of-care testing (POCT) sensors. (1)Biosensors and Bioelectronics 25 (2010) 1767–1773

      8:00 PM - B7.23

      Tunable Magnetic Properties of Electrochemically Deposited CoNiReP Alloys: From Nanostructured Thin Films to Templated Nanoarchitectures

      Salvador  Pane Vidal1, Eva  Pellicer2, Kartik  M  Sivaraman1, Arif  M  Zeeshan1, Simone  Schuerle1, Maria  D  Baro2, Josep  Nogues2 3 4, Jordi  Sort2 3, Bradley  J  Nelson1.

      Show Abstract

      Fabricating micro and nano devices with integrated permanent magnetic components that exhibit appropriate magnetic properties has proven challenging to the micro and nanoelectromechanical systems (MEMS/NEMS) research community. While many research efforts have been pursued to develop processes for integrating hard magnets into devices, the processes significantly affect both the magnetic properties of the material and the entire device design due to constraints that the processes place on the fabrication sequence [1]. For example, despite the excellent hard-magnetic properties of NdFeB and SmCo alloys, methods to produce high-aspect ratio micro and nanostructures with these materials suffer from a lack of repeatability and undesirable oxidation . We have recently investigated several electrochemical deposition strategies, including direct plating, pulse plating, reverse pulse plating, and electroless plating, to produce high performance CoNiReP hard-magnetic alloys with tunable material properties. Patternable films, nanowires, and helical and tubular structures have been created. The processes developed can be economically upscaled and provide relatively few constraints on subsequent process flow. Using direct plating and reverse pulse plating with applied current densities ranging from -10 to -50 mA cm-2, we have attained films with intrinsic coercivities (Hc) as high as 3.5 kOe and energy products up to 6.2 MG Oe [2]. Films up to 3 μm thick that can be patterned by photolithography have been achieved with newly developed electrolytes. Pulse plated CoNiReP nanowires with semi-hard-magnetic properties have also been fabricated using porous anodized aluminum oxide templates. Hc values ranging from 290 to 590 Oe along the nanowire axis were obtained. Helical and tubular structures have been created in which the diacetylenic phospholipid 1,2-bis(10,12-tricosadionyl)-sn-glycero-3-phosphocholine (DC8,9PC) is used as a template. The phospholipidic nanostructures were metalized by electroless CoNiReP plating. The magnetic properties of all of these structures have been fully characterized. In addition, all structures were wirelessly manipulated using a 5-degree-of-freedom electromagnetic manipulation system [3] to investigate their potential as platforms for targeted drug delivery. [1] S. Guan et al., J. Electrochem. Soc. 152 (2005), C190. [2] S. Pané et al., Electrochim. Acta 13 (2011), 8979. [3] M. Kummer et al., IEEE Trans. on Rob. 26 (2010), 1006.

      8:00 PM - B7.24

      The Investigation on the Heterogeneous Integration of Silicon and Germanium by Low Temperature Wafer Bonding Technology

      Xuanxiong  Zhang1 2, Yi  Ou1, Fan  Yang1, Tianchun  Ye1, Songlin  Zhuang2.

      Show Abstract

      The heterogeneous integration of Si and Ge is attracting more attentions in the fields of microelectronics because Ge with higher carrier mobility of electrons and holes can be used as the transistor channel for future CMOS [1]. Ge has to integrate with silicon to sufficiently make use of the platform from the matured silicon CMOS technology. On the other hand, Ge can play an important role in the combination of silicon and III-V compound semiconductor owing to the matched lattice parameter between Ge and III-V [2]. However, ~4% lattice difference between Ge and silicon results in high defect density during Ge epitaxy on silicon [3]. Moreover, Ge-on-insulator (GeOI), such as silicon-on-insulator (SOI) structure, should be employed to suppress the current leakage caused by narrow bandgap as Ge is used as a transistor channel material. Wafer bonding is enabling technology to achieve heterogeneous integration due to match-free requirement of lattice pattern instead of the direct Ge epitaxy on silicon. However, the process of the heterogeneous wafer bonding has to be performed under the low temperature thanks to the difference of thermal expansion coefficient between both materials. There are a great number of defects in GeOI manufactured by the smart-cut® process [4] but the origin of the defects in GeOI is not being reported to date. The atomic level Ge/SiO2 wafer bonding was demonstrated by 150°C annealing in the previous study [5] but the inspection for tiny voids at the bonding interface was restricted because of the reflecting infrared imaging. In this paper, we will report the origin of voids at the interface of wafer bonding between Ge and silicon by the detection of scanning acoustic microscope (SAM) with high resolution and the approach to suppress voids. For comparison, Ge/Si and Ge/SiO2 wafer bonding were performed by 150°C annealing. Based on Si/Si and Si/SiO2 wafer bonding, the visible voids (observed by infrared transmission imaging) at the Si/Si interface can be viewed but the invisible voids can be only detected by the testing of bonding strength [6]. In particular, it is difficult to examine the invisible voids in the wafer bonding with oxide because the porous oxide may absorb interface voids [7]. Our results indicated that the voids at the Ge/SiO2 bonding interface can be also generated although the voids are more sensitive in Ge/Si wafer bonding due to the inappropriate wafer bonding approach. As a result, an improved method will be obtained to suppress the interface voids. [1] D. Lin, G. et al. IEEE International Electron Devices Meeting, (2009) 327-330. [2] W.K. Liu, et al., J Cryst Growth, 311 (2009) 1979-1983. [3] V.A. Shah, et al., Solid State Electron, 62 (2011) 189-194. [4] T. Akatsu, et al., Mat Sci Semicon Proc, 9 (2006) 444-448. [5] X.X. Zhang, et al., ECS Transactions, 33(3) (2010) 457-466. [6] X.X. Zhang, et al., Electrochem Solid St, 8 (2005) G268-G270. [7] Q.Y. Tong, et al., J Microelectromech S, 3 (1994) 29-35.

      Download Session Locator (.pdf)2012-04-13  

      Symposium B

      Show All Abstracts

      Symposium Organizers

      • Kazuya Masu, Tokyo Institute of Technology
      • Kazuaki Sawada, Toyohashi University of Technology
      • Hiroshi Toshiyoshi, The University of Tokyo Institute of Industrial Science
      • Benoit Charlot, Université Monptellier II Institute d'Electronique de Sud
      • Albert P. Pisano, University of California, Berkeley

      Support

      • Japan Society of Applied Physics

        B8: Process

        • Chair: Hiroshi Toshiyoshi
        • Friday AM, April 13, 2012
        • Moscone West, Level 2, Room 2000
         

        8:30 AM - *B8.1

        High-Speed MEMS Optical Phased Array for Agile Beamforming

        Ming  Wu1.

        Show Abstract

        Agile optical phased arrays (OPA) not only enable optical beam steering but also beam forming and multiple beam generation. Compact OPAs have numerous applications, including 3D imaging, gesture-based sensing, gaming, LIDAR, precision targeting, navigation, remote sensing, and laser communications. Previously, OPAs have been realized using liquid crystals and photonic integrated circuits with phase modulator arrays. However, liquid crystals are limited to low speed operation, and phase modulator array requires complex integration process to achieve two-dimensional OPA. Micro-electro-mechanical-system (MEMS)-based OPAs have also been demonstrated, however, the trade-offs between resonance frequency and actuation voltage preclude their operation in MHz range. In this paper, we report on a novel MEMS-based OPA that can simultaneously achieve large phase shift (2 pi), high bandwidth (> MHz), low actuation voltage (10V), and high power handling capability. This is enabled by high-contrast grating (HCG) mirrors comprising a single, thin layer (500 nm) of sub-wavelength gratings. The reflectivity of HCG can be controlled by tailoring the thickness, pitch, and grating width. High reflectivity (> 99.5%) can be achieved in HCG that weights only a few percent of multi-layer distributed Bragg reflectors with similar reflectivity. The single material construction also prevents mirror warping due to mismatch of thermal expansion coefficient. To further reduce the actuation voltage, we integrate the HCG mirror with an all-pass optical filter to amplify the phase shift. Simulation shows that actuation voltage below 10V can be achieved. This project is supported by DARPA SWEEPER (short-range wide-field-of-view extremely-agile electronically-steered photonic emitters) program.

        9:00 AM - B8.2

        Surface and Internal Structure Effects on the Energy Dissipation in Electromechanical Resonators

        Orcun  Ergincan1, George  Palasantzas1.

        Show Abstract

        Our research focuses on energy dissipation as a function of resonator size and shape with a particular emphasis on the influence of surface and internal structure effects. The surfaces of commercial Si cantilever are modified using focused ion beam (FIB) in a controlled way to produce various patterns and surface roughnesses. Cantilevers with patterned surfaces formed using different etch line orientations and alignments show different responses and sensing properties. Noise measurements of the resonating cantilever with modified surfaces are compared with those of unmodified ones. From the power spectrum densities of the noise measurements the quality factors (Q) are obtained and calculated at room temperature. The experiments for the measurement of Q are performed starting from high vacuum conditions up to atmospheric pressure. With changing pressure the dominant loss mechanisms acting on the resonator also changes. Currently, we are studying the effect of FIB on the cantilever Q factor at high vacuum conditions. Under these conditions the quality factor correspond to energy dissipation due to internal cantilever dissipation mechanisms. The differences in beam currents of the FIB lead to different surface degradations. The noise experiments shows large changes in the Q factor due to different chosen beam currents of ion etching. High beam current etching of surface structures lead to cantilevers that show large internal dissipation and change of surface structure. On the other hand, low beam current etching lead to cantilevers that show less surface structure change and less internal dissipation. When low beam current ion etching technique is used for changing surface topographies of the cantilever, the change in Q factor related to the topography is distinguishable from the rest of the loss mechanisms.

        9:15 AM - B8.3

        Novel Route for a Vapor Phase Modification of Silicon Oxide Surfaces

        Malgorzata  Adamkiewicz1, Tony  O’Hara2, David  O’Hagan1, Georg  Haehner1.

        Show Abstract

        Microelectromechanical Systems (MEMS) made of silicon are playing an increasingly important role in areas such as health care, for example as patient monitoring systems, and energy, e.g. in the form of micro fuel cell systems based on MEMS technology. A current challenge for a wider and quicker adoption of MEMS is the development of new or improved coating procedures with ultrathin organic films in order to protect them from the environment or to functionalize their surfaces [1]. Self-assembly provides a simple route to modify selected surfaces by using monolayers of long chain organic molecules with various functional groups. Versatile functional groups at the surface allow a careful tuning of surface properties such as wettability, corrosion resistance, and biocompatibility. Most of the organic reactions that were successfully conducted with self-assembled monolayers (SAMs) comprise carbon-heteroatom bond formations [2, 3]. We have developed a novel route for SAM functionalization in the gas phase. In a first step we deposited vinyl-terminated SAMs from the vapor phase onto SiOx/Si substrates [4]. Subsequently, a chemical modification of the olefin on the surface was performed via carbene reaction in the gas phase. The resulting coatings were characterized with respect to their hydrophobicity, surface roughness, homogeneity, chemical composition, film thickness and thermal stability indicating high quality films. The procedure offers significant potential for application on an industrial scale. [1] MEMS Mechanical Sensors, (Ed.: S. Beeby, G. Ensell. M. Kraft, N. White), Artech House London 2004. [2] B. J. Ravoo, D. N. Reinhoudt, S. Onclin, Angew. Chem. Int. Ed., 2005, 44, 6282. [3] N. Herzer, S. Hoeppener, U. S. Schubert Chem. Commun., 2010, 46, 5634. [4] M. Adamkiewicz, T. O’Hara, D. O’Hagan, G. Haehner submitted.

        9:30 AM - B8.4

        Ultra Conformal Metal Deposition in Extremely High Aspect Ratio Features of MEMS Devices by Supercritical Fluid Deposition

        Takeshi  Momose1, Aiko  Kondo2, Yukihiro  Shimogaki1, Masakazu  Sugiyama3.

        Show Abstract

        We have developed novel supercritical fluid deposition (SCFD) technique enabling metal deposition on Si and insulating underlayers. It had been a technological challenge for applying SCFD to MEMS fabrication because SCFD selectively deposits metal films on conductive underlayers. Thanks to conformal deposition capability of SCFD, 200nm-thick Cu film was conformally formed on Si trenches with extremely high aspect ratio (HAR) of 125. SCFD, which is a reduction of metal organic compounds by hydrogen in supercritical carbon dioxide (scCO2), is reported to be a promising technology for superior gap filling and structure-independent conformal deposition on extremely HAR features. A possible reason for this process performance is due to large precursor concentration in scCO2, which realizes Langmuir-Hinshellwood (LH)-type nonlinear surface reaction kinetics. The deposition rate becomes nearly independent to the precursor concentration at high concentration range in LH-kinetics. The concentration independent growth is favorable for the conformal deposition. For example, we demonstrated 10nm-thick, smooth, and continuous film formation and complete gap-filling of Cu into ultra narrow HAR vias with Ru surface (70 nm diameter and 1 μm depth). However, SCFD selectively deposits metal films on conductive underlayers, because the reducing agent, H2, is only activated on metallic surfaces. This was a reason why SCFD was not used in MEMS devices in spite of an increasing demand for metal coating on HAR (>100) structure such as wiring in 3D packaging and electrode contacts to the channels in micro-fluidic chips. Therefore, novel SCFD technique which realizes metal coating on Si and insulating underlayers will allow us to explore new frontier for MEMS fabrication. Our-developed glue layer having composite structure of Cu and MnOx made by SCFD could be deposited even on insulating layer, and works as a catalyst for metal SCFD. Because deposition of oxide films is known to exhibit no dependence on underlayers, MnOx works as a glue of Cu and an underlayer, and Cu incorporated in MnOx film functions a catalyst. For the CuMnOx layer to serve both as glue and catalyst for Cu deposition, the stoichiometry of CuMnOx is vital to strike a balance between metal and oxide. By optimizing the chemistry, CuMnOx film was conformally formed on Si HAR trenches (0.57 μm diameter and 71.2 μm depth, thus aspect ratio of 125) and Cu was then conformally deposited on it. Since the gap-filling of Cu using metallic underlayers was already established, Cu filling on HAR features with Si and an insulating surface will be achievable using this technique. The CuMnOx glue layer is also applicable for the deposition of other metals such as Au, Ni, and Co on Si and insulating surfaces. This breakthrough extends the applicability of SCFD to numerous MEMS applications, and provides the flexibility of MEMS design such as wiring on back side of overhung structure.

        9:45 AM - B8.5

        Metal Oxide Electrode Fabrication in Supercritical Carbon Dioxide for Embedded FeRAM Application

        Kyubong  Jung1, Takeshi  Momose1, Yukihiro  Shimogaki1.

        Show Abstract

        SrRuO3 (SRO) has gained more interest as electrode materials for ferroelectric random access memory. Especially, SRO is the most promising materials because of its crystal structure. SRO has perovskite structure found in ferroelectric materials. Therefore, ferro-electricity of FeRAM can be improved by using SRO as an electrode. Usually SRO is fabricated by metal organic chemical vapor deposition (MOCVD) at relatively high temperature. However, high temperature process causes several problems. To decreasing energy consume, FeRAM can be used in monolithic integration as a cash memory (Embedded FeRAM). In this case, logic devise is formed first generally. Therefore, it can be damaged during FeRAM fabrication at high temperature. Other problem is the evaporation of certain material such as Bi and Pb in ferroelectric layer due to its high evaporation volatility. SRO deposition can be done in supercritical carbon dioxide (scCO2) at low temperature. This deposition method called as supercritical fluid deposition (SCFD) using scCO2 as a medium. Supercritical fluid (SCF) is the state above critical pressure and temperature, and has high solubility and diffusivity. It looks like liquid but has low surface tension. Therefore, deposition on a high aspect ratio with superior coverage at low temperature is possible using SCFD Sr(tmhd)2 and Ru(tmhd)3 were used with oxygen gas. We employed silicon wafer with 100nm thermal SiO2 as substrate. Partial pressure of O2 was varied from 1 to 4MPa to examine the oxidizing agent concentration effect. The deposition process was carried out using a hot wall reactor at 250°C, 15MPa of total pressure of CO2 and O2. Precursors were loaded into reactor before heating and pressurizing. After reaching desired temperature and pressure, it was held for 30 min. After deposition, purging process was carried out using only high purity liquid CO2 at 10MPa for 30min to eliminate residual un-reacted precursor and byproducts. The deposited samples were characterized by FE-SEM and XRD. XRD results showed SRO was successfully formed at 250°C from Ru(tmhd)3 and Sr(tmhd)2 using 3MPa of oxygen. However, when lower than 2MPa of O2 was used, RuO2 was formed because of higher reactivity of Ru precursor than for Sr. Oxidant is usually reacted with Ru precursor due to reactivity difference of precursors. Therefore, RuO2 is fabricated if oxidant is not enough. The excessive oxidizer concentration also induces RuO2 film. As a result, when 4MPa of O2 was used, ruthenium oxide was formed. It can be explained by same mechanism. In summary, SrRuO3 film was successfully deposited using SCFD at low temperature. This process will enable embedded FeRAM fabrication to realize low-power consumption device.

        10:00 AM -

        BREAK

        Show Abstract

        B9: Material

        • Chair: Seiichi Hata
        • Friday AM, April 13, 2012
        • Moscone West, Level 2, Room 2000
         

        10:30 AM - *B9.1

        Novel Device Structures from Carbon Based MEMS and NEMS

        Sang Wook  Lee1.

        Show Abstract

        In this presentation, the possible applications of carbon based MEMS and NEMS are presented. Among carbon based structures, carbon nanotubes and graphene were chosen for the main materials of our studies. The three novel device structures, those are a transistor with carbon nanotube channel and suspended graphene based moving gate, an electromechanical non-volatile memory, and a graphene based mechanical resonators will be introduced. Novel field effect transistors with suspended graphene gates are demonstrated. By incorporating mechanical motion of the gate electrode it is possible to improve the switching characteristics. A new concept of non-volatile memory based on the carbon nanotube field effect transistor together with microelectromechanical switch will be introduced. A graphene xylophone structure which is composed of array of graphene resonators is suggested for its RF applications.

        11:00 AM - B9.2

        Out-of-plane Bending Reliability Test for Intrinsic Mechanical Strength of Polycrystalline Silicon Thin Film Using Etching-damage-less Membrane

        Tomoki  Tanemura1 2, Shuichi  Yamashita1, Hiroyuki  Wado1, Yukihiro  Takeuchi1, Toshiyuki  Tsuchiya2, Osamu  Tabata2.

        Show Abstract

        Polycrystalline silicon (Poly-Si) has been widely utilized as movable structure and often subjected to cyclic loading at high frequency under harsh environment such as high temperature and humidity in MEMS (Micro Electro Mechanical Systems). Although various researches about mechanical strength of Poly-Si have been reported, its reliability including initial fracture strength and fatigue lifetime has not been revealed completely [1-4]. One of the main reasons is large standard deviation (SD) in strength (2.55GPa in average and 28% in SD) [1], which is caused by the surface roughness of side walls formed by etching process for fabricating specimens. Thus, a new method which can eliminate etching influence for specimen should be developed to evaluate intrinsic material’s reliability. In this paper, we have proposed and demonstrated, for the first time, a novel testing method without applying the stress on the etched surface roughness. The specimen is a square membrane of 250-nm- and 500-nm-thick Poly-Si thin film. The membrane has a cylindrical Si-weight in the center and is supported by Si frame. Load to the membrane is applied by vibrating the Si frame in out-of-plane direction around the resonant frequency. The vertical displacement of Si-weight generated by resonant vibration is measured using a laser displacement sensor and the stress distribution of poly-Si membrane is calculated from the measured displacement using FEM analysis. The initial fracture strength of the film can be evaluated by breaking the membrane, since the fracture origin is on the surface free from etching process damages. We have evaluated the initial fracture strength by gradually increasing the displacement of the shaker. The initial fracture strength of poly-Si was 2.59GPa and 2.28GPa in average and its SD was 0.17GPa (6.6%) and 0.28GPa (12.1%) with 250nm and 500nm thickness of poly-Si membrane, respectively. The difference of average and SD of strength in thickness of membrane is explained by increase of surface roughness. Surface roughness measured by AFM was 1.8nm and 2.6nm for 250nm and 500nm thickness poly-Si, respectively. The average strength was almost same but SD was extremely small compared to the previous research result [1]. It is found that the developed method can decrease the SD and evaluate intrinsic initial fracture strength as mentioned above. As a next step, fatigue lifetime will be also examined using the same setup with long-term constant cyclic loadings. [1]T. Tsuchiya et al., IEEJ Transactions on Sensors and Micromachines, 116, 10 (1996). [2]D.A. Lavan et al., American Society for Testing and Materials, 1413 (2000) [3]W.N. Sharpe Jr et al, Mechanics of Materials, 36 (2004) [4]S. Kamiya et al., Journal of Micromechanics and Microengineering, 18 (2008)

        11:15 AM - B9.3

        Controlling Crystallization Structures in Si Thin Film for Improving Characteristics of MEMS Resonator

        Shinya  Kumagai1 3, Hiromu  Murase1, Takashi  Tomikawa1, Shohei  Ogawa1, Ichiro  Yamashita2 3, Yukiharu  Uraoka2 3, Minoru  Sasaki1 3.

        Show Abstract

        Crystallization structures in the Si thin film affect the performance of MEMS/NEMS. Grain structures degrade mechanical characteristics of the film. Energy losses occur at the grain boundaries during device actuation. High temperature annealing (650-800°C) improves crystallinity of the deposited Si thin film [1,2]. However, random generation of crystallization nuclei limits the improvement. Grain growth is stopped by the collision with neighboring grains. To control the nuclei generation, we used metal-induced lateral crystallization (MILC) using Ni nanoparticles (NPs) synthesized within cage-shaped protein, apoferritin [3]. Because apoferritin molecules (φ12nm) are generated according to gene information, they have atomically the same structure. Using them as templates, uniform φ7nm NPs are synthesized. The size-regulated NPs are ideal “nanoblocks” for constructing functional structures [4]. Amorphous Si film (600nm) was deposited on a Si substrate with thermally oxidized layer (3μm). P ions were implanted into the Si film for electric conduction. Apoferritin molecules with Ni NPs were adsorbed on the amorphous Si film. The protein parts were eliminated by heat treatment (500°C, O2: 0.5slm) to leave Ni NPs on the surface. Positions of the Ni NPs determined the positions of crystallization. The sample was annealed for MILC (680°C, Ar: 0.5slm). The adsorbed Ni NPs reacted with Si to form silicide NiSi2. NiSi2 is generated at lower than 400 deg. Because NiSi2 has similar lattice constant with Si (mismatch: 0.4%), the NiSi2 functions as crystallization nuclei before the thermally generated nuclei induce the random crystallization. Electron BackScatter Diffraction analysis revealed crystallization structure in the Si film. Without MILC, grain was less than 1μm. With MILC, the grain reached 50-60μm. Crystalline orientations were almost the same direction. MEMS resonators were fabricated with the Si film and actuated under atmosphere. MILC shift the resonance frequency from 656 kHz to 676 kHz. This is explained by the enhanced tension by MILC [5]. Tensions measured by MEMS strain gauges were 368MPa and 461MPa, without and with MILC, respectively. Q factor increased from 36.3 to 42.3. 20% increase was observed. The improved crystallinity of the Si film contributed to increase the Q factor. Device operation under vacuum can increase the Q factor. For the advanced MILC, Ni ferritin molecules were patterned [4]. Crystallized area expanded outwards from the Ni ferritin patterned area. Crystallization structures in the MEMS/NEMS devices can be controlled by designing Ni ferritin adsorption positions. This study is supported by CREST/JST and KAKENHI (21710128), JSPS. [1] A. Ferri et al., J. Appl. Phys., 100 (2006) 094311 [2] H. Miura et al., Appl. Phys. Lett., 60 (1992) 2746 [3] H. Kirimura et al., Appl. Phys. Lett., 86 (2005), 262106. [4] I. Yamashita et al., Biochim. Biophys. Acta, 1800 (2011) 846 [5] S. Kuamgai et al., Proc. Transducers ’11, p. 1733

        11:30 AM - B9.4

        High Density Piezoelectric Micro-machined Ultrasonic Transducers Array Using Epitaxial PZT Thin Film on γ-Al2O3/Si Substrate

        Katsuya  Ozaki1, Keisuke  Suzuki1, Yasuyuki  Numata1, Nagaya  Okada2, Daisuke  Akai1 3, Makoto  Ishida1 3.

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        In the medical field, ultrasonic diagnostics is indispensable technology due to many advantages compared to X-ray and CT devices such as non-invasive, on-site investigation, and compact and simple equipments. Recently, further small and high resolution two-dimensional array transducers are required for the three-dimensional imaging intravascular endoscope application. Pb(ZrxTi1-x) O3(PZT) ceramics which shows high piezoelectricity is used to conventional ultrasonic transducers. However, PZT ceramics is not suitable for micro-fabrication process and is difficult to form connecting wires for array transducers by conventional wire bonding technique. Micro-machined Ultrasonic Transducers (MUTs) on Si substrates are essential to realize above applications. MUTs have smaller element size than conventional ceramics transducers and the acoustic wavelength. We have proposed epitaxial PZT thin film which is grown on epitaxial γ-Al2O3 as a buffer layer on Si substrate for monolithically integrated with piezoelectric MUTs and Si-LSI. An element of our proposed pMUTs array has a semispherical cavity under piezoelectric PZT thin films formed by surface bulk micromachining technique using XeF2 gas etching. Advantages of this technique are suitable for miniaturization and high density integration compared with conventional back-side etching technique such as TMAH etching. Moreover, a circular shape attains higher density than a square shape. In this research, we demonstrate high density piezoelectric micro-machined ultrasonic transducers array using epitaxial PZT thin film on γ-Al2O3/Si substrate. Fabricated pMUTs array is 100μm in diameter with 56 elements/mm2. Semispherical cavity under the 500nm-thick PZT thin film diaphragm was formed by XeF2 gas etching through the hole about 10μm in diameter from the surface of the transducer. Ultrasonic wave transmitting experiment was carried out using fabricated pMUTs as a transmitter and a commercial PZT hydrophone as a receiver. AC voltage (1.2MHz, 10Vp-p) was applied to the pMUTs under water to generate transmitting ultrasonic waves. Transmitted ultrasonic wave was received by a commercial ultrasonic hydrophone locating 1.5cm far from fabricated pMUTs. As a result, fabricated pMUTs has been successfully generated ultrasonic wave with 1.2MHz which is same frequency of applying voltage. Furthermore, the transmitting power - frequency characteristic under water was measured with changing frequency ranges from 1.0MHz to 8.0MHz. The pMUTs has the first resonance frequency at 1.2MHz, second resonance frequency at 1.6MHz, and third resonance frequency at 2.2MHz. These frequency ranges can be applied to medical ultrasonic diagnosis application.

        11:45 AM - B9.5

        All-oxide PiezoMEMS Devices by Pulsed Laser Deposition

        Matthijn  Dekkers1 2, Ruud  Steenwelle1, Xin  Wan1, Evert  Houwman1, Guus  Rijnders1.

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        In this contribution, I will highlight the recent progress on the fabrication of all-oxide piezo-MEMS devices by pulsed laser deposition. In our devices, we use Pb(Zr,Ti)O3 (PZT) as the piezoelectric material. The ferro- and piezoelectric properties are strongly related to the crystal orientation as well as the strain state of the PZT layer. Successful integration of these devices into silicon technology is therefore not only dependent on the ability of epitaxial growth on silicon substrates, but also the control of the crystallographic orientation as well as the strain state. We have fabricated all-oxide piezoMEMS devices and studied the resulting properties, such as piezomechanical actuation and sensor properties. In the contribution, I will further highlight our recent progress on large area deposition by PLD. Currently, we are able to fabricate piezoMEMS devices using a 200 mm technology.

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