Plasma etch method with enhanced endpoint detection

摘要

A plasma etch method for etching a silicon oxide containing material layer with respect to a silicon nitride etch stop layer employs an etchant gas composition comprising octafluorocyclobutane and oxygen, without a carbon and oxygen containing gas. An endpoint within the plasma etch method is determined by monitoring the concentration of the carbon and oxygen containing gas. The plasma etch methods provides for enhanced endpoint detection.