Low-damage dry etching process of Sc-Sb-Te phase-change memory film using a chlorine-based reactive atmosphere

Scandium antimony telluride (Sc-Sb-Te), a promising nonvolatile cache-type phase-change memory (PCM) material, exhibits remarkable characteristics such as ultrafast crystallization speed, commendable amorphous thermal stability, and minimal resistance drift. In order to attain large-capacity storage and high-parallel computing capabilities, the construction of high-density memory arrays composed of nano-scaled PCM cells employing the Sc-Sb-Te material is not only essential but also inevitable. Dry etching methodologies represent the mainstream approach in this regard, while the conventional process employing the fluorine-based reactive atmosphere, which has been effectively implemented on Ge-Sb-Te-like PCM materials, induces substantial cross-sectional damages and interfacial residues within the etched Sc0.3Sb2Te3 thin film. Here, we develop and optimize the chlorine-based dry etching techniques to address the issue, achieving low-damage and sharp sidewall etching morphologies, thanks to the reduction of chlorine element residue and the formation of volatile scandium chloride products. Our work offers a valuable technological guideline for the nanofabrication procedures involved in the production of ultra-scaled, high-density Sc-Sb-Te-based PCM chips.