Ting Chien - Cupertino CA,
Christine Nelson - Santa Clara CA,
Douglas Keil - Fremont CA,
A semiconductor manufacturing process wherein a dielectric layer is plasma etched with selectivity to an underlying and/or overlying stop layer such as a silicon nitride layer. The etchant gas includes a hydrogen-free fluorocarbon reactant such as CFgas wherein y/x 1.5, an oxygen-containing gas such as Oand a carrier gas such as Ar. The etch rate of the dielectric layer can be at least 10 times higher than that of the stop layer. Using a combination of CF, Oand Ar, it is possible to obtain dielectric: nitride etch selectivity of greater than 30:1 and nitride cornering etch selectivity of greater than 20:1. The process is useful for etching vias, contacts, and/or trenches of a self-aligned contact (SAC) or self-aligned trench.