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:
Nov. 02, 1999
Filed:
Apr. 26, 1996
Toshimitsu Konuma, Kanagawa, JP;
Akira Sugawara, Kanagawa, JP;
Takeshi Nishi, Kanagawa, JP;
Yukiko Uehara, Shizuoka, JP;
Satoshi Murakami, Kanagawa, JP;
Misako Nakazawa, Kanagawa, JP;
Semiconductor Energy Laboratory Co., Ltd., Kanagawa-ken, JP;
Abstract
An alumina film, a silicon oxide film, and a silicon nitride film formed on a substrate containing a large amount of alumina are etched by using an etching material in which the concentration of ammonium fluoride, which is a component of BHF, is set low. Etching is performed by using an etching material that is an aqueous solution produced by mixing hydrofluoric acid, ammonium fluoride and water at a weight ratio of x:y:(100-x-y) where x and y satisfy a relationship y<-2x+10 (0<x.ltoreq.5, 0<y.ltoreq.10). 50% hydrofluoric acid on the market and 40% aqueous solution of ammonium fluoride are used.