If Si CMOS for massive M3D is difficult due to need for high-thermal-budget processes, are there solutions that are beyond Si? In this article, we discuss two low-thermal budget approaches: Oxide Semiconductor and 2D Materials for M3D integration. By reviewing some of our recent work with IGZO-based transistors and memories, followed by our investigation of the 2D material opportunities for 3D memories, we highlight the need for new low-thermal-budget additive techniques for heterogenous multi-material integration as well as low-temperature material modification. Given the unlikelihood of “perfect materials”, new system architecture-material-device co-design intervention will be essential to capitalize on the specific trade-offs of the components.

Researcher/Author: 
Aaron Voon-Yew Thean^†, Evgeny Zamburg^†, Shih-Hao Tsai, Chun-Kuei Chen, Maheswari Sivan, Baoshan Tang, Sonu Hooda, Zihang Fang, Jieming Pan, Jinfeng Leong, and Hasita Veluri. 

Published in: 2022 International Electron Devices Meeting (IEDM)

https://ieeexplore.ieee.org/document/10019501

We demonstrate, for the first time, a short-channel (L G :40nm) back-end-of-line (BEOL) compatible top-gated (TG) self-aligned FeFETs with the ultra-low interface/bulk trap density (D it /D bulk ) down to 10 ¹¹ cm ^-2 eV ^-1 , a 100x improvement over conventional amorphous Indium-Gallium-Zinc-Oxide (IGZO) devices. High memory and drive performance are both achieved, exhibiting a large and stable memory window of 2.1V, excellent endurance exceeding 10 ⁷ cycles, close-to-ideal subthreshold swing (S.S.) of 62mV/dec., and the record-low read-after-write delay of 200ns. This is accomplished by utilizing the defect self-compensation effect in the ITO-IGZO heterojunction channels for ferroelectric top-gate stack stabilization. We leverage these advantages and proposed a novel Monolithic 3D (M3D) FPGA architecture with the demonstrated short-channel (L G :40nm) BEOL dual-gated (DG) merged memory-logic FeFETs with excellent drive performance as a non-volatile reconfigurable interconnect switch. Our BEOL-compatible DG FeFET switch enables a compact interconnect switch fabrics with a V/2 bias scheme, featuring excellent G on /G off of 10 ⁶ , ultra-low sub-pA leakage, disturb-free, and sneak-current-free read-write operation. This work sets new oxide-semiconductor FeFET performance records useful for future BEOL nonvolatile logic applications.

Researcher/Author from Department of Electrical and Computer Engineering: 
Aaron Voon-Yew Thean; Evgeny Zamburg; Chun-Kuei Chen; Zihang Fang; Sonu Hooda; Manohar Lal; Umesh Chand; Zefeng Xu; Jieming Pan; Shih-Hao Tsai

Published in: 2022 International Electron Devices Meeting (IEDM)

https://ieeexplore.ieee.org/document/10019440