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:
May. 07, 1996
Filed:
Sep. 13, 1994
Applicant:
Inventors:
Anthony Ledger, Newfairfield, CT (US);
Michael Power, Newtown, CT (US);
Assignee:
Hughes Aircraft Company, Los Angeles, CA (US);
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01B / ;
U.S. Cl.
CPC ...
356357 ; 356360 ;
Abstract
A transparent chuck is used to force a semiconductor wafer to take a prescribed shape. Any gap which is formed between the chuck and the wafer can be imaged through the transparent chuck. An interferometer is used to illuminate the gap with a narrow band illumination to create interference fringes in the gap. The fringes can be electronically imaged to create a digital input to a computer. Merit functions corresponding to the total volume of fringes in the gap or to the summation of nearest neighbor slopes of such fringes provide a measure of the thickness of such gap.