Method of etching a deep trench having a tapered profile in silicon
AssigneeApplied Materials, Inc.
InventorsMichael Rattner, Jeffrey D. Chinn
Life of this patent
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Abstract
Disclosed herein is a method of etching deep trenches in a substrate which utilizes the overlying mask structure to achieve a trench having a positive tapered sidewall angle of less than about 88°. The method employs the successive etching of a lateral undercut in the substrate beneath a masking material, while at the same time etching vertically downward beneath the mask. The coordinated widening of the lateral undercut at the top of the trench, while vertically extending the depth of the trench, is designed to provide the desired trench sidewall taper angle.
Claims36
A method of etching trenches in a substrate which have a trench depth of at least 20 μm and a positive tapered sidewall angle of less than about 88°, wherein the method employs a masking layer overlying said substrate, and the successive etching of a lateral undercut in said substrate beneath said masking layer, while at the same time etching vertically downward beneath said masking layer, and wherein a coordinated widening of said lateral undercut at the top of said trench with said vertical downward etching provides said positive tapered sidewall angle.
A method of etching a trench in a silicon substrate, wherein the method includes:
- a) an etching step comprising exposing said silicon substrate, through a patterned masking layer, to a plasma generated from a fluorine-containing gas;
- b) a polymer deposition step comprising exposing said silicon substrate to a plasma generated from a gas which is capable of forming a polymer on etched silicon surfaces;
- and
- c) alternatingly repeating said etching step and said polymer deposition step, wherein said etching step and said polymer deposition step are performed at a process chamber pressure within the range of about 30 mTorr to about 150 mTorr, and wherein a bias power of about 35 W or less is applied to said substrate during said etching step.
Dependencies are inferred from the claim text.