Optical emission spectroscopy of zinc sulfide etch

Abstract

Optical emission spectroscopy was used to gain insight into the reactive ion etching (RIE) of zinc sulfide films in a hydrogen plasma. Evaporated, metal organic chemical vapor deposited (MOCVD), and sputtered zinc sulfide films were examined. The zinc atomic emission at 472 nm was used to monitor the etching reaction. Hydrogen atom emissions at 656 and 486 nm were also explored but were found to be less sensitive to the etching reaction. The zinc atomic emission data was found to be a very reproducible method of end point detection and was sensitive to etch rate, uniformity, and mechanism differences among the evaporated, MOCVD, and sputtered ZnS films. End point detection was demonstrated for patterned and unpatterned samples. Implementing end point detection for this reaction eliminates the problems associated with overetching and the need for separate processing parameters for each type of ZnS film.