Patent ID: 8017493

Claim:
A process of forming a semiconductor process fabricated device, comprising steps: providing a substrate; forming a cavity in said substrate; forming a fill material layer in said cavity and on a top surface of said substrate adjacent to said cavity by a conformal deposition process, such that a fill layer depression is formed in a top surface of said fill material layer over said cavity; forming a sacrificial planarizing layer on said top surface of said fill material layer, such that a thickness of said sacrificial planarizing layer over said fill layer depression is greater than a thickness of said sacrificial planarizing layer over said substrate adjacent to said cavity by at least half a depth of said fill layer depression; and performing a selective planarization RIE process, such that: said sacrificial planarizing layer is etched such that said fill material layer is exposed over said substrate adjacent to said cavity while material of said sacrificial planarizing layer remains in said fill layer depression; said fill material layer is subsequently etched concurrently with said sacrificial planarizing layer in said fill layer depression, whereby an etch rate of said fill material layer is at least five times an etch rate of said sacrificial planarizing layer; said sacrificial planarizing layer is subsequently removed from said fill layer depression, whereby an existing top surface of said fill material layer over said cavity is higher than an existing top surface of said fill material layer over said substrate adjacent to said cavity; said fill material layer is subsequently removed from said top surface of said substrate adjacent to said cavity, whereby an existing top surface of said fill material layer over said cavity is higher than said top surface of said substrate adjacent to said cavity; and subsequently continuing said selective planarization RIE process in an overetch step, whereby an existing top surface of said fill material layer over said cavity is substantially planar.