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:
Feb. 15, 2011
Filed:
Feb. 20, 2007
Applicants:
Katsuya Hirano, Tokyo, JP;
Mohammad B. Shabani, Tokyo, JP;
Inventors:
Katsuya Hirano, Tokyo, JP;
Mohammad B. Shabani, Tokyo, JP;
Assignee:
Sumco Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01L 21/302 (2006.01); H01L 21/461 (2006.01);
U.S. Cl.
CPC ...
Abstract
This method for assaying copper in silicon wafers includes the steps of: forming a polysilicon layer on the surface of a p-type silicon wafer having the same characteristics as the silicon wafers being assayed; heat treating the p-type silicon wafer after it has been polished; dissolving the polysilicon layer on the heat-treated p-type silicon wafer with a mixed acid composed of at least hydrofluoric acid and nitric acid; and quantitatively determining the copper components within the mixed acid following dissolution of the polysilicon layer.