Synergistic Performance and Yield Improvement of Embedded RRAM Product through Process Optimization in 40 nm CMOS Platform
Authors: Zhenchao Sui, Yanqing Wu, Zhichao Lv, Xing Zhang
To address the challenges of complexity, power consumption, and cost constraints in traditional display driver integrated circuits (DDICs) caused by external NOR Flash and SRAM, this work proposes an embedded resistive random-access memory (RRAM) integration solution based on a 40 nm high-voltage CMOS logic platform. Targeting the yield fluctuations and stability challenges during RRAM mass production, systematic process optimizations are implemented to achieve synergistic improvements in RRAM performance and yield. Through modifications to the film sputtering and pre-deposition treatment, the within-wafer resistance uniformity (RSU) of the oxygen-deficient layer (ODL) thin film is improved from 11% to 8%, while inter-wafer process stability variation reduces from 23% to below 6%. Consequently, the yield of 8 Mb RRAM embedded mass production products increases from 87% to 98.5%. In terms of device performance, the RRAM demonstrates a fast 4.8 ns read speed, exceptional read disturb immunity of 3 × 10^8 cycles at 95 °C, 10^3 write/erase endurance cycles for the 1 Mb cells, and data retention of 12.5 years at 125 °C. Post high-temperature operating life (HTOL) testing exhibits stable high/low resistance window. This study provides process optimization strategies and a reliability assurance framework for the mass production of highly integrated, low-power embedded RRAM display driver IC.
