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:
Oct. 05, 1999
Filed:
Jul. 27, 1998
Bill Kalenian, San Luis Obispo, CA (US);
Terry L Lentz, Templeton, CA (US);
Strasbaugh, San Luis Obispo, CA (US);
Abstract
Apparatus for use in a semiconductor wafer polishing machine of a type in which the wafer is picked up and held by a suction cup effect between the wafer and a resilient diaphragm on the wafer carrier. The apparatus permits the presence or absence of a wafer on the carrier to be sensed so that this information can be used in controlling the operation of the machine. In normal operation, a vacuum is applied to a downwardly-opening plenum that is covered by a resilient diaphragm. The present invention is the addition to the wafer carrier of an air conduit opening into the plenum through an air port and connected to an orifice so that air can flow through the orifice, through the air conduit and the air port into the plenum at a rate that is slow relative to the capacity of the vacuum pump. The present invention further requires the addition of a pressure sensor for sensing the pressure in the air conduit or alternatively in the vacuum conduit. The sensed pressure in the vacuum conduit is lower in the absence of a wafer than in the presence of a wafer, and the sensed pressure in the air conduit is greater in the absence of a wafer than it is when a wafer is present.