Surface Roughness in Plasma-Etched $\hbox{As}_{\bf 2}\hbox{S}_{\bf 3}$ Films: Its Origin and Improvement

Abstract

We describe the microstructure of As2S3 films and its effect on the morphology of plasma-etched surfaces. The Raman spectroscopy and X-ray photoelectron spectroscopy demonstrated that the observed grainy morphology of etched As2S3 surfaces comes from differential chemical attack between different phases within the film. Two approaches were found to be effective for improving the smoothness of etched surfaces: a change in the plasma chemistry from CF4-O2 to CHF3-O2 and the application of a thin-conformal coating onto structures already patterned using CF4-O2 plasma.