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:
May. 27, 1997
Filed:
Jan. 12, 1994
Applicant:
Inventor:
Donald C Grant, Excelsior, MN (US);
Assignee:
FSI International, Inc., Chaska, MN (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B01D / ; C01B / ;
U.S. Cl.
CPC ...
203 12 ; 134 10 ; 134 11 ; 134 12 ; 159D / ; 203 13 ; 203 35 ; 203 40 ; 203 42 ; 203 49 ; 203 71 ; 4233942 ; 423488 ; 423531 ;
Abstract
A method of recycling and purifying cleaning chemicals used in the production of semiconductor circuits and containing hydrofluoric acid and or hydrochloric acid. Recycling of such chemicals is accomplished using separation and reconstitution steps Hydrofluoric acid and hydrochloric acid cannot be distilled directly from a chemical solution as they form azeotropes with water. A low vapor pressure substance such as sulfuric acid or phosphoric acid is used to break the azeotrope while increasing the purity of the recovered chemicals and decreasing disposal problems. The method is useable at the point of use of the chemicals.