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:
Jan. 31, 1995
Filed:
Mar. 25, 1993
Anthony Ledger, New Fairfield, CT (US);
Hughes Aircraft Company, Los Angeles, CA (US);
Abstract
The thickness of the entire surface of a thick semiconductor (94) layer on an insulator is determined all at once by dividing the surface into a plurality of pixels, by varying the length of a variable length optical path (110) in a Michelson interferometer (66) having an infrared source (62), illuminating the entire surface of the layer with an image of the IR source during the length variation operation, and by detecting (64) the product of the intensity (I.sub.s (z)) from the Michelson interferometer and the reflectivity R(t) of the layer as the path length is varied, such being indicative of the thickness of the layer, and by determining, for each pixel, which one of a plurality of groups of stored reflectance values, for a corresponding plurality of thicknesses, best matches the detected values, thereby providing a thickness map of the semiconductor layer.