Atomic Layer Deposited Oxygen‐Deficient TaOx Layers for Electroforming‐Free and Reliable Resistance Switching Memory

Abstract

Oxygen‐deficient TaOx layers are grown by a radical‐enhanced atomic layer deposition (REALD) process on a chemically active bottom electrode (Ta) to create electroforming‐free resistance switching random access memory (ReRAM) cells. When the top electrode is Pt, the Ta/TaOx/Pt device shows a completely electroforming‐free behavior with a pulse‐switching induced endurance cycle of up to 6 × 106 cycles. This is due to the abundantly present oxygen vacancies within the TaOx layer, which eliminate the need to create further oxygen vacancies during the electroforming cycles in other types of oxide‐based ReRAM cells. The adoption of the Pt top electrode contributes to the suppression of the leakage current, making the switching reliable. When the top electrode is changed to the more production‐compatible Ru, which is also grown by another REALD, the devices show very mild electroforming behavior with an increased leakage current. Due to these slight decreases in the electrical performance, the switching endurance can be confirmed only up to 6 × 104 cycles with the help of an incremental step pulse programming technique.