X-ray photoelectron spectroscopic study of Ge2 Sb2 Te5 etched by fluorocarbon inductively coupled plasmas

X-ray photoelectron spectroscopy was used to determine the level of surface fluorination damage of Ge2 Sb2 Te5 (GST) etched by fluorocarbon gases at different F/C ratios. When blank GST was etched, the gas with a higher F/C ratio produced a thinner C-F polymer on the etched surface but fluorinated Ge, Sb, and Te compounds were observed in the remaining GST. When the sidewall of the etched GST features was investigated, a thicker fluorinated layer was observed on the GST sidewall etched by the higher F/C ratio gas, indicating more fluorination due to the difficulty in preventing F diffusion into the GST through the thinner C-F layer.