Molybdenum Etching Using CCl4/O2 Mixture Gas

Abstract

Molybdenum was etched using CCl₄/O₂ mixture gas. Typical etch rate is about 80 nm/min, and its relative etch rate ratio to resist AZ1350J was 2: 1. Etch rates of silicon and silicon-dioxide were negligibly small, as compared to molybdenum etch rate. The dissociation process of CCl₄/O₂ analogous to the dissociation process in CF₄/O₂ mixture gas plasma was observed. Molybdenum-oxide was detected on the surface of silicon, silicon-dioxide and the resist, which were etched with molybdenum, using Auger electron spectroscopy. The deposited molybdenum-oxide increases the etch selectivity of molybdenum over underlying materials. The lateral etching rate after etching end point was about 13 nm/min, in the typical etching condition. The main reason for the pattern width narrowing in the etching was due to moderate resist slope.