Optimization of WAl_2O_3Cu(-Te) Material Stack for High-Performance Conductive-Bridging Memory Cells

摘要

In this paper, we optimize the thermal stability of WAl_2O_3Cu and WAl_2O_3Cu-Te conductive-bridging cells for integration of 1-Transistor/1-Resistor (1T1R) memory elements. Thermal stability up to the back-end-of-line (BEOL) processing temperature of 400℃ is ensured by Cu-Te composition tuning and carbon alloying developments, while Cu in-diffusion processes during BEOL processing is limited through the engineering of thin Ti-, Ta-, and TiW-based metallic liners inserted at the Al_2O_3Cu(-Te) interface. The integrated 1T1R cells are demonstrated to operate in the nanosecond range using moderate voltages. Write endurance of ＞10~6 cycles is achieved using 10ns-short pulses while high voltage-disturb robustness is observed at lower voltages, resulting in excellent voltage-time characteristics of the cells. Finally, images of device filaments programmed in low- and high-resistance states are successfully obtained by means of conductive atomic-force-microscopy.