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. 28, 1995
Filed:
Sep. 15, 1994
Akira Nakada, Yotsukaido, JP;
Akira Yoneya, Narashino, JP;
Noriyuki Kobayashi, Sodegaura, JP;
Mamoru Katayanagi, Asaka, JP;
Tsutomu Kawashima, Koto, JP;
Hiroshi Yoshida, Iwatsuki, JP;
Nisso Engineering Co., Ltd., Tokyo, JP;
Abstract
A method for purifying an etching solution consisting of an aqueous phosphoric acid solution which has been used in etching of a silicon nitride film. In the process, hydrogen fluoride is added to an etching solution consisting of an aqueous phosphoric acid solution which has been used for etching of a silicon nitride film, and the resulting solution is heated to remove fluorides of silicon as reaction products of hydrogen fluoride with silicon compounds which have been contained in the etching solution together with vaporized water.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile