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:
Dec. 09, 1997
Filed:
Jul. 01, 1996
Applicant:
Inventor:
Toshiaki Kitano, Tokyo, JP;
Assignee:
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01L / ; H01L / ; B44C / ; C09K / ;
U.S. Cl.
CPC ...
438172 ; 438745 ; 252 794 ;
Abstract
An etchant includes an aqueous solution containing citric acid, ammonium citrate, and hydrogen peroxide, wherein the mol ratio of ammonium citrate to citric acid is not less than 1. Using this etchant, a WSi layer on an InAlAs layer can be etched selectively with respect to the InAlAs layer.