Method for preventing micromasking in shallow trench isolation process etching

摘要

An isolation structure on an integrated circuit is formed using a shallow trench isolation process. A layer of buffer oxide is formed on a substrate. A layer of nitride is formed on the layer of buffer oxide. The layer of nitride and the layer of buffer oxide are patterned to form a trench area. The substrate including the trench area is subjected to a plasma comprising H2O vapor, and a gaseous fluorocarbon or a fluorinated hydrocarbon gas to clean impurities on the trench area. The substrate is etched to form a trench within the trench area.