- Mark D. Poliks, Binghamton University
Nancy Stoffel, GE Global Research
James Watkins, University of Massachusetts Amherst
Methods to integrate electronic devices and manufacture on rigid silicon wafers are well established; device dimensions have continued to shrink and performance continues to increase each year. Flexible hybrid electronics promises to deliver high performance and reliable systems in novel forms and functions. This is achieved by utilizing high-performance, silicon-based semiconductor devices assembled on flexible circuits using optimized materials and processes. Integration of electronic devices on flexible substrates (flex) is starting to enable dramatically new approaches to traditional applications including: information displays, lighting, sensors, solar energy conversion and diagnostic medicine. The tutorial will examine the fundamental aspects of three approaches: chip-on-flex (Stoffel), micron scale thin-film devices on flex (Poliks) and sub-micron scale self-assembled/imprinted device based coatings on flex (Watkins).
The challenges to meet this vision include the reliable integration of rigid low CTE devices and components on flexible or even stretchable substrates. Standard methods and materials of integration utilized for printed circuit boards will not work due to the thermal requirements of the substrates and the need for flexibility. The use of creative manufacturing methods involving the selective use of direct solder attachment of thin silicon die to achieve high performance in truly miniature sized electronic packages will also be covered. The tutorial will begin by covering current and developing approaches used for integration of millimeter-scale semiconductor devices, sensors and transducers, including creation of thin die, die singulation, die handling and attach, interconnection and encapsulation on flexible substrates.
During the second segment, micron-scale thin-film electronic device fabrication directly on flexible non-silicon-wafer surfaces will be described. Engineered polymer films such as PET, PI, and PEN, as well as thin flexible metal foils and glass are all viable substrates for this technology. Key substrate properties include: dimensional and thermal stability, low moisture uptake, ultra-low gas and moisture transmission rates and nanoscale surface roughness. This segment will examine how some of the basic semiconductor manufacturing processes can be adapted for use with flexible substrate materials and suggest a means for roll-to-roll manufacturing of flexible hybrid electronics. Advancements in manufacturing processes such as roll-to-roll handling, slot-die coating, ink-jet printing, vacuum deposition, photolithography and wet processing will be described.
The emerging technologies in printed and flexible electronics that can enable next-generation performance will be discussed in the third segment. Nanoscale fabrication techniques, including the self-assembly of hybrid (inorganic/organic) materials and imprint patterning using polymers, hybrid polymer/inorganic resists and crystalline nanoparticle ink systems, can resolve challenges associated with large-area production of sub-micron device features leading to very high integration densities as well as cost-effective production of functional device components. Applications include printing of 2D and 3D crystalline inorganic structures for light and energy management, printed micron-scale transistors and printed microfluidic sensors. In addition, printing of functional structures to modify the performance and behavior of adjacent components and attached Si dies for flex-hybrid, enabling customized performance, will also be discussed.