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. 01, 1998
Filed:
Sep. 10, 1996
Applicant:
Inventors:
John H Keller, Orange County, NY (US);
Gregory Costrini, Dutchess County, NY (US);
Assignee:
International Business Machines Corporation, Armonk, NY (US);
Primary Examiner:
Int. Cl.
CPC ...
H05H / ; H01L / ;
U.S. Cl.
CPC ...
438 10 ; 438474 ; 438798 ;
Abstract
Apparatus controls a wafer potential in a plasma system when the plasma is off to keep the wafer slightly negative at all times in order to reduce and eliminate the collection of charged particles on the wafer. The apparatus allows the wafer bias to be reduced to a small negative voltage and then holds that voltage. This greatly reduces the net positive flux to the wafer. A diode and a programmed power supply hold a minimum negative voltage on the back of the wafer electrode when the plasma density is decaying to zero.