Etchant with selectivity for doped silicon dioxide over undoped silicon dioxide and silicon nitride, processes which employ the etchant, and structures formed thereby

Abstract

A selective dry etch process includes use of an etchant that includes CHF, where x is an integer from three to five, inclusive, where y is an integer from one to three, inclusive, and where x plus y equals six. The etchant etches doped silicon dioxide with selectivity over both undoped silicon dioxide and silicon nitride. Thus, undoped silicon dioxide and silicon nitride may be employed as etch stops in dry etch processes which utilize the CHF-containing etchant. CHFmay be employed as either a primary etchant or as an additive to another etchant or etchant mixture.