Patent ID: 11107699

Abstract:
A semiconductor manufacturing process is provided. A trench is formed in a semiconductor structure and an oxide layer is deposited on sidewalls of the trench. A solid-state by-product layer is formed on surfaces of the trench by introducing a first etchant gas to react with a naturally occurred oxide layer at the bottom of the trench and the deposited oxide layer. The solid-state by-product layer has a thickness on the bottom less than a thickness on the sidewalls. A second etchant gas is introduced into the trench to react with the solid-state by-product layer, thereby providing a thinned solid-state by-product layer on the sidewalls to protect the deposited oxide layer. By a heating process, the thinned solid-state by-product layer is removed from the sidewalls of the trench, exposing the deposited oxide layer and a surface portion of the semiconductor structure in the trench.