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. 09, 2003
Filed:
May. 01, 2002
Hiroaki Yanagida, Tokyo, JP;
Hideaki Matsubara, Nagoya, JP;
Yoshiki Okuhara, Aichi, JP;
Shoji Aoki, Aichi, JP;
Naoki Kawashima, Nagoya, JP;
Bruce T. Williams, Lockport, NY (US);
Toshio Uehara, Tokyo, JP;
Other;
Abstract
A platen for electrostatic wafer clamping apparatus comprising a platen body of dielectric material and grains of electrically conductive material diffused in the dielectric material so that the platen has a relatively large electrostatic capacitance due to the diffusion of the conductive grains with the result that the platen provides an increased clamping force regardless of humidity. In accordance with another aspect of the invention, the thickness of the platen body can be decreased by an amount sufficient to maintain a constant clamping force with reduced applied voltage, to eliminate any residual voltage on the platen and to increase the speed of wafer release. The grains of electrically conductive material are present in an amount of from about 2.5 percent to about 15.0 percent of the volume of the platen body, and the grains of electrically conductive material are selected from the group consisting of carbonated transition metals, nitrified transition metals and carbonated grains. The dielectric material preferably is Al O , and the grains of electrically conductive material preferably are TiC and preferably in an amount of about 5% of the volume of the platen.