Reactive ion etching of an ovonic threshold switch (OTS) material using hydrogen-based plasmas for non-volatile phase change memories

Abstract

Etch characteristics of ovonic threshold switch (OTS) materials composed of Ge–As–Te for a phase-change random access memory (PCRAM) has been investigated using reactive ion etching by hydrogen-based gases such as H2, CH4, NH3, CH4 + H2, and CH4 + NH3.

Study on Hydrogen-Based Reactive Ion Etching of Ovonic Threshold Switch (OTS) Materials for Phase Change Memory Devices

“…The OTS selector layer is generally fabricated by etching using halogen gases. However, during the etching process, halides are formed on the sidewall of etched chalcogenide compounds, and which penetrate into the sidewalls of the OTS pattern and damage the phase change characteristics (7)(8)(9)(10). Therefore, it is necessary to develop a dry etch process that reduces chemical damage to OTS materials and enables precise etching.…”