Patent ID: 9082719
Filing Date: 2015-07-14
Classification: H01L

Abstract:
1. A method for removing a dielectric layer from a bottom of a trench while maintaining the dielectric layer on sidewalls of the trench, the method comprising: providing a substrate, wherein the trench is formed in the substrate, and wherein the bottom of the trench and the sidewalls of the trench are covered with the dielectric layer; etching the dielectric layer at the bottom of the trench and generating a passivation layer on the dielectric layer at an upper portion of the trench by adjusting conditions of a plasma etch process to a first mode; and etching the dielectric layer at the bottom of the trench and etching the passivation layer at the upper portion of the trench by adjusting the conditions of the plasma etch process to a second mode before the dielectric layer at the bottom of the trench is completely removed, wherein the dielectric layer comprises nitride.