Study on Etching Process and Mechanism of New Phase Change Material Ti0.5Sb2Te3

The dry etching characteristic of new Ti0.5Sb2Te3(TST) phase change material was investigated by using the CF4 and Ar gas mixture. The research mainly focuses on how to optimize the experimental parameters such as gas flow rate within the chamber, CF4 /Ar flow ratio, the chamber background pressure and the incident RF power applied to the lower electrode. The results show that CF4 mainly plays a role of chemical etching and Ar plays a role of physical bombardment. The etching rate of TST films increases with the increasing concentration of CF4 in the gas mixture. The etching chamber pressure has less effect on the TST film etching speed, while the etching power has larger effect. The etch rate is up to 126 nm/min with the smooth etched surface(RMS=0.82 nm) and TST film profile is almost vertical(approaching 90°) using optimized etching parameters, including the total flow rate of 50 sccm, CF4 concentration of 26%, power of 400 W and pressure of 13.3 Pa.