Signal and Thermal Integrity Analysis of 3-D Stacked Resistive Random Access Memories

In this article, a 3-D electrothermal numerical model is used to perform the signal and thermal integrity analysis of 3-D stacked Resistive-switching random access memory (RRAM) arrays. Two main issues are found: voltage drop along the interconnects and thermal crosstalk between the memory cells. Possible solutions to these issues are here thoroughly investigated, based either on new biasing schemes or new materials. Especially, conventional nickel bars are replaced by interconnects made by copper (Cu) and carbon nanotubes (CNTs), whose electrical and thermal parameters are here described using physically based models. The analysis is performed on a $5\times 5\times5$ array, under a real case of a RESET switching, which is the worst case scenario from the electrothermal point of view. Simulation results show that the use of CNTs reduces the voltage drop in both word and bitline (BL) interconnects, thermal crosstalk, and the maximum working temperature; hence, it mitigates many of the crucial issues in the roadmap for the large-scale monolithic 3-D RRAM integration.