학술논문
Demonstration of a Multi-Level μA-Range Bulk Switching ReRAM and its Application for Keyword Spotting
Document Type
Conference
Author
Wu, Y.; Cai, F.; Thomas, L.; Liu, T.; Nourbakhsh, A.; Hebding, J.; Smith, E.; Quon, R.; Smith, R.; Kumar, A.; Pang, A.; Holt, J.; Someshwar, R.; Nardi, F.; Anthis, J.; Yen, S-H.; Chevallier, C.; Uppala, A.; Chen, X.; Breil, N.; Sherwood, T.; Wong, K.; Cho, W.; Thompson, D.; Hsu, J.; Ayyagari, B.; Krishnan, S.; Lu, Wei. D.; Chudzik, M.
Source
2022 International Electron Devices Meeting (IEDM) Electron Devices Meeting (IEDM), 2022 International. :18.4.1-18.4.4 Dec, 2022
Subject
Language
ISSN
2156-017X
Abstract
Despite the great promises of resistive random-access memory (ReRAM) for fast, low-power in memory computing, the models deployed on ReRAM crossbars suffer from accuracy loss, due to poor yield, inaccurate switching and high noise. In this paper, we report a forming-free bulk ReRAM (b-ReRAM) cell that can be programmed up to 128 levels between 400nA $(4\mu \mathrm{S})$ and $4\mu A (40\mu S)$. The device operates by continuous modulation of bulk oxygen vacancies, therefore exhibiting favorable characteristics including forming-free operation, analog switching, low noise and low operating currents [1], [2]. The multilayer ReRAM stack is deposited using a specially built 300mm deposition system that features a clustered sequence of Physical Vapor Deposition (PVD) and Atomic Layer Deposition (ALD), leading to high wafer-level yield and uniformity. High programming accuracy can be achieved over 25k b-ReRAM devices across 15 dies. A fully integrated system on chip (SoC) with BEOL-integrated b-ReRAM arrays is built with 65nm CMOS technology, and keyword spotting (KWS) is demonstrated with accuracy equivalent to the software quantized model and high energy efficiency at 98.5 TOPS/W. Moreover, we evaluate the performance of the bitcell for large neural network (NN) applications in a custom hardware-aware simulation platform and show that software comparable accuracy can be achieved. This work for the first-time reports that high yield and high programming accuracy can be achieved with b-ReRAM at the wafer-level scale and demonstrates that superior analog behavior enables the mapping of NN models onto the ReRAM-based SoC prototype with no accuracy loss and high energy efficiency.