METHODS OF FORMING VARYING DEPTH TRENCHES IN SEMICONDUCTOR DEVICES

摘要

A method of forming trenches in a semiconductor device includes forming an etchant barrier layer above a first portion of a semiconductor layer. A first trench is etched in a second portion of the semiconductor layer using a first etchant. The second portion of the semiconductor layer is not disposed underneath the etchant barrier layer. The etchant barrier layer is etched through using a second etchant that does not substantially etch the semiconductor layer. A second trench is etched in the first portion of the semiconductor layer using a third etchant. The third etchant also extends a depth of the first trench.