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:
Sep. 28, 1999
Filed:
Nov. 14, 1997
Iku Shiota, Isehara, JP;
Kyo Tsuboi, Sagamihara, JP;
Tokyo Electron Limited, Tokyo, JP;
Abstract
After the release of the application of an attraction voltage to an electrostatic chuck that is attracting a semiconductor wafer, the wafer is pushed upward by lifting pins through only a very small projection distance. Immediately after processing has ended, the temperature of the wafer is several tens of degrees higher than that of the electrostatic chuck so that, if the wafer has detached, the temperature of the rear surface thereof will fall toward the original temperature of the electrostatic chuck. If the wafer has not detached, the temperature thereof will not fall. Therefore, a determination is made as to whether the wafer has detached or whether it is being subjected to residual attraction, based on temperature change data obtained for the wafer in combination with the electrostatic chuck, by a temperature sensor after the wafer has been pushed upward by a very small projection distance. If there is residual attraction, wafer transfer is halted. This makes it possible to prevent damage to the wafer that would occur if an unreasonable force is applied to the wafer by the residual attraction when the wafer is being detached from the electrostatic chuck.