Selective oxide-to-nitride etch process using C4F8/CO/Ar

摘要

A dry etch process for use in the fabrication of integrated circuits which use SiN etch stop layers is disclosed. The process is conducted in a reactive-ion etch reactor and employs a gaseous etchant mixture comprised of octaflourocyclobutane (C4F8), carbon monoxide (CO) and Ar. The specific process parameters effect the formation of a polymer on SiN but not on oxide, thereby resulting in a very high etch rate selectivity of the oxide to the nitride.