The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 09, 2011
Filed:
Oct. 30, 2009
William A. Wojtczak, Austin, TX (US);
Sian Collins, Austin, TX (US);
William A. Wojtczak, Austin, TX (US);
Sian Collins, Austin, TX (US);
Sachem, Inc., Austin, TX (US);
Abstract
A process for etching a silicon layer disposed on a substrate, including anisotropically etching a first trench in the silicon layer; selectively anisotropic wet etching silicon surfaces in the first trench, the wet etching comprising exposing the silicon surfaces to an aqueous composition including an aromatic tri(lower)alkyl quaternary onium hydroxide, and an unsymmetrical tetraalkyl quaternary phosphonium salt; in which the wet etching etches (110) and (100) planes of the silicon layer at about equal rates and preferentially to the (111) plane to form an enlarged trench having a sidewall in the (111) plane. A silicon alloy may be epitaxially deposited in the thus-produced trench as part of a process of introducing stress into at least a portion of the silicon layer.