Plasma etching uniformity control

摘要

Plasma etching is controlled utilizing two etchant gases to form a plasma so as to obtain controlled (e.g., uniform) etch rate across a wafer. One etchant gas forms appositive plasma, which is the dominant plasma. The other etchant gas forms a negative plasma, which is the secondary plasma. The ratio of dominant plasma to the secondary plasma can be adjusted such that ion densities are uniform across the wafer, resulting in uniform etch rate over the wafer.