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:
Oct. 30, 2012
Filed:
Oct. 08, 2009
Applicants:
Takahisa Nakashima, Karatsu, JP;
Makoto Takemura, Imari, JP;
Yasuyuki Hashimoto, Imari, JP;
Inventors:
Assignee:
Sumco Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C09K 13/00 (2006.01);
U.S. Cl.
CPC ...
Abstract
An alkali etching liquid for a silicon wafer that includes an aqueous solution of potassium hydroxide, and from 0.1 g/L to 0.5 g/L of diethylene triamine pentaacetic acid. Furthermore, the Fe concentration of the aqueous solution of potassium hydroxide is no more than 50 ppb. An etching method that including a step of etching a silicon wafer with a resistivity of no more than 1 Ω·cm using the etching liquid.