RRAM Devices with Plasma Treated HfO2 with Ru as Top Electrode for In-Memory Computing Hardware

Abstract

This work investigates the role of extra oxygen vacancies, introduced by a hydrogen plasma at midpoint of deposition of a 6 nm thick HfO2 to reduce the switching power consumption in a RRAM device. Initially TiN, which is a commonly used metal in CMOS technology, was used as the top electrode for treated HfO2. Subsequently Ru and TaN as top electrodes were explored enhance the switching behavior and power consumption. A range of compliance currents from 1 nA to 1 mA were used to evaluate the switching characteristics. The role of both TaN and Ru as bottom metal was also evaluated. With Ru as top metal the device switched at a compliance current of 1 nA and higher. Whereas when Ru was used as bottom electrode, devices were unable to switch below a compliance current of 50 mA. For TaN as top metal electrode, devices switched at and above 1 mA CC whereas with TaN as bottom metal the initial switching was at CC of 2 mA. It was observed that use of Ru as a top metal significantly reduced the switching energy of the plasma treated HfO2 RRAM device but was ineffective when used as a bottom metal.