Patent ID: 6566273
Filing Date: 2003-05-20
Classification: H01L

Abstract:
A method for expanding trenches comprising the steps of:forming a trench in a substrate having side walls including at least two crystallographic planes, a first one of the at least two crystallographic planes, a first one of the at least two crystallographic planes being etchable at a faster rate than a second one of the at least two crystallographic planes; selectively growing a dielectric layer of surfaces of the at least two crystallographic planes such that the dielectric layer includes a greater thickness on the first one of the at least two crystallographic planes than on the second one of the at least two crytallographic planes; and etching the dielectric layer and the substrate such that an etch rate of the second one of the at least two crystallographic planes is effectively etched at a faster rate than the first one of the at least two crystallographic planes, wherein the etching process expands a lower portion of the trench.