Selective suppression of dry-etch rate of materials containing both silicon and nitrogen

Abstract

A method of suppressing the etch rate for exposed silicon-and-nitrogen-containing material on patterned heterogeneous structures is described and includes a two stage remote plasma etch. The etch selectivity of silicon relative to silicon nitride and other silicon-and-nitrogen-containing material is increased using the method. The first stage of the remote plasma etch reacts plasma effluents with the patterned heterogeneous structures to form protective solid by-product on the silicon-and-nitrogen-containing material. The plasma effluents of the first stage are formed from a remote plasma of a combination of precursors, including nitrogen trifluoride and hydrogen (H). The second stage of the remote plasma etch also reacts plasma effluents with the patterned heterogeneous structures to selectively remove material which lacks the protective solid by-product. The plasma effluents of the second stage are formed from a remote plasma of a fluorine-containing precursor.