Enhancing Memory Retention of FAB Compatible ECRAM Devices using an Ion Blocking Layer

Traditionally, the only ions allowed or welcomed by the microelectronic industry are those that act as fixed dopants. The issue of mobile ions became welcome primarily due to the memristor technology however, thin film transistor technologies benefit from them too. The electrochemical (transistor) random access memory (ECRAM) is emerging as a promising building block for multi-level neuromorphic computing. Using FAB-compatible materials we construct the ECRAM using CuOx as the gate and ions source (Cu+). The morphology of the HfOx gate insulator layer is finetuned to render it ion transporting such that it can act as a uniform electrolyte layer. Lastly, the channel material is WOx with tungsten metal as the source/drain contact.<br/>While there are several reports of ECRAM devices, the operation mechanisms are not fully known/understood thus withholding progress of this field. Using the Sentaurus device simulator by Synopsis, including the hydrogen diffusion module, we simulate the mixed ionic electronic operation of the device. We have recently reported that by fitting the simulation to the device performance we could identify the potentiation mechanism (i.e., insulator charging) and the occurrence of copper plating that takes place under high Cu+ ion flux (as in fast charging of Li batteries).[1]<br/>In the first part of the talk, we will expand on the chemical-physics details of the ECRAM device mentioned above. Next, we will present a new device architecture where an ion-barrier layer is introduced and is shown to enhance memory retention. The third device structure is where we remove the WOx layer and study the ionic-electronic conduction of a modified HfOx layer.<br/>Using the above three device architectures in conjunction with the mixed ionic-electronic device simulation we reveal the role of the two memory mechanisms: a) Electric field-activated ion transport and b) Structure-induced trapping by ion-barrier layers.<br/><br/><b>Reference</b><br/>[1] Nir Tessler, Nayeon Kim, Heebum Kang, Jiyong Woo; Switching mechanisms of CMOS-compatible ECRAM transistors—Electrolyte charging and ion plating. <i><i>J. Appl. Phys.</i></i> 21 August 2023; 134 (7): 074501. https://doi.org/10.1063/5.0154153