Etching of new phase change material Ti0.5Sb2Te3 by Cl2/Ar and CF4/Ar inductively coupled plasmas

The etching characteristics of new phase change material Ti0.5Sb2Te3 (TST) were studied with the Cl2/Ar or CF4/Ar gas mixture using inductively coupled plasmas system. The effects of gas-mixing ratio, bias power, gas pressure, applying ICP power on the variations of etch rate, etch profiles, and surface roughness were investigated, respectively. Furthermore, X-ray photoelectron spectroscopy (XPS) compositional depth profiling was used to determine the surface degradation of etched TST using Cl2/Ar and CF4/Ar gas mixture. The etched TST shows a shift of the peaks related to Sb and Te to a higher energy for both etching gas, indicating the surface degradation of TST after etching. TST etched by Cl2 shows a thicker chloride layer remaining on the etched surface than fluorinate layer etched by CF4 owing to the higher reactivity. In the case of CF4, a thinner C-F polymer layer was observed on the etched surface, indicating lower etch rate due to the difficulty in making F diffusion into the TST through the C-F layer.