Patent ID: 7951683

Claim:
A semiconductor processing method for high-aspect-ratio gapfill, comprising: (a) providing a substrate with at least one high-aspect-ratio feature; (b) depositing a dielectric layer to partially fill the feature, wherein the depositing stops before a gap opening of the feature closes; (c) depositing an etch selectivity layer to at least partially plug the gap opening; (d) etching the substrate to reduce the aspect ratio of the feature, wherein the etching comprises a first etch operation and a first etch chemistry, wherein the partially filled feature achieved in operation (b) is substantially protected, and wherein the etching removes the etch selectivity layer in regions surrounding the at least partially plugged gap opening to expose the dielectric layer but does not remove all of the etch selectivity layer of the partially plugged gap opening; and (e) etching the substrate to remove the etch selectivity layer from the gap opening and open the feature, wherein the etching comprises a second etch operation and a second etch chemistry, at least one of the first etch operation and the first etch chemistry being different from the second etch operation or the second etch chemistry.