Reduction of thermal disturbances in 3D 1S1R RRAM crossbar arrays for neuromorphic computing

Abstract

Recently, analog behaviors in resistive random-access memory (RRAM) have been proposed as a promising circuit implementation for neuromorphic computing. However, to date, there have been relatively few studies on the issue of resistance degradation (computing weight) induced by thermal disturbances in high-density RRAM arrays. In this paper, thermal simulations of a three-dimensional (3D) one-selector, one-resistor (1S1R) RRAM crossbar array for neuromorphic computing were performed using the COMSOL Multiphysics software. Four factors influencing the thermal disturbance problem were considered: distances between adjacent devices, thermal conductivity of the insulating material, the resistance of the low-resistance state (LRS) of the RRAM, and the programming speed. Thermal disturbances were found to be more severe when the device spacing was less than 200 nm. Higher thermal conductivities of the insulating material, a larger LRS resistance, and a faster operational speed were found to effectively reduce the thermal disturbances in 3D 1S1R RRAM crossbar arrays. The use of sub-nanosecond pulses solved the thermal issues to the greatest extent.