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:
Mar. 12, 1991
Filed:
May. 10, 1990
James T Clemens, Watchung, NJ (US);
Shane Y Hong, Berkeley Heights, NJ (US);
AT&T Bell Laboratories, Murray Hill, NJ (US);
Abstract
Disclosed is apparatus comprising an electrostatic cassette assembly for securing a semiconductor wafer during lithographic processing such as direct-write particle-beam lithography. The cassette assembly comprises a cassette body and an electrostatic chuck installable in, and removeable from, the cassette body. The electrostatic chuck comprises a charge plate having a thin dielectric layer on its upper surface, against which the wafer is flattened by Coulombic force. Charge storage means are included for maintaining an electrical potential difference between the wafer and the charge plate even in the absence of connection to a source of electrical energy external to the assembly.