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:
Feb. 25, 1997
Filed:
Jun. 22, 1994
Nobuo Kawada, Gunma-ken, JP;
Kazuhiro Yamaguchi, Gunma-ken, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
A novel ceramic electrostatic chuck with built-in heater is proposed which is outstandingly durable in use with repeated cycles of heating and cooling because of the absence of troubles due to exfoliation of layers and crack formation in the ceramic body. Differently from conventional ceramic electrostatic chuck with built-in heater consisting of a base plate of sintered body of boron nitride, layers of pyrolytic graphite formed on the surfaces of the base plate to serve, one, as the electrode layer and, the other, as the heater element, and an insulating layer of pyrolytic boron nitride formed on the pyrolytic graphite layers, the base plate in the invention is made of a composite sintered body of a powder mixture of aluminum and boron nitrides in a specified mixing proportion so as to minimize the difference in the thermal expansion coefficient from those of the overlaying layers.