Patent ID: 8450194

Claim:
A method of modifying a shape of a cavity in a substrate, comprising: forming one or more cavities on a surface of the substrate between adjacent relief structures; directing ions toward the substrate at a non-normal angle of incidence, wherein the ions strike an upper portion of a cavity sidewall and are provided at an ion energy and ion dose that forms an altered portion of the substrate proximate the upper portion of the cavity sidewall, and wherein the ions do not strike a lower portion of the cavity sidewall; etching the one or more cavities using a wet etch that etches unaltered substrate material faster than the altered portion of the substrate wherein the upper portion of the cavity sidewall etches more slowly than the lower portion of the cavity sidewall and wherein the wet etch etches substrate material along a first crystallographic plane faster than along a second crystallographic plane; and epitaxially growing an embedded region within the one or more cavities, wherein the embedded region comprises a keystone shape.