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:
Jun. 20, 2000
Filed:
Oct. 14, 1997
Yoshihiro Hayashi, Tokyo, JP;
Yukishige Saito, Tokyo, JP;
Tsutomu Nakajima, Tokyo, JP;
Shin Sato, Tokyo, JP;
Yukihiro Furukawa, Tokyo, JP;
NEC Corporation, , JP;
Abstract
A polishing agent recovery and reuse method and device for the same removes large impurities by a filtration device, concentrates by an ultrafiltration device, and continuously recovers polishing agent. Polishing agent used in polishing a semiconductor board or a coating formed on top of a semiconductor board is collected in a pre-processing container after use. Large impurities are removed by a dual fine filtration device. The resulting filtrate is concentrated by an ultrafiltration device. The concentrated solution may then be mixed with filtrate from the dual fine filtration device to further concentrate the polishing agent. The concentration of the polishing agent in the concentrated solution, the pH, and the temperature of the solution are continuously monitored and controlled. The filtrate of the ultrafiltration device is further treated to remove impurities, resulting in pure or ultrapure water. The recovered polishing agent may be reused in further polishing steps.