Interface modification of HfO2-based ReRAM via low temperature anneal

Abstract

Resistive Random Access Memory (ReRAM) is a novel form of non-volatile memory with a variety of applications ranging from neuromorphic circuits used for artificial intelligence applications, to a potential replacement for flash memory. Each application has specific requirements including Roff/Ron ratio, maximum variability tolerance, retention, endurance, and operating voltages. Tuning of individual performance metrics for a particular application often results in performance trade-offs. In this work, we demonstrate the adjustment of the above-mentioned parameters via manipulation of the pre-forming oxygen vacancy gradient using a controlled annealing step with nanoscale HfO2-based ReRAM devices. ReRAM devices of 100 × 100 nm2 were implemented between the metal 1 and 2 interconnect in a custom designed split via process, using 65 nm CMOS processing technology. A temperature study on these devices was performed to optimize the oxygen vacancy gradient from the switching layer to the oxygen scavenger layer. Devices in a 1 transistor/1 ReRAM (1T1R) configuration were subjected to 300 °C–400 °C, for 1–120 min and then electrically characterized using DC switching and endurance testing. Based on the results of this study, we outline the temperature constraints for post-fabrication drive-in of oxygen vacancies via annealing-based treatment of HfO2 based ReRAM devices.