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. 08, 1994
Filed:
May. 29, 1992
Anthony M Ledger, New Fairfield, CT (US);
Hughes Aircraft Company, Los Angeles, CA (US);
Abstract
An apparatus (1) that measures the thickness of a thin film layer of a wafer (24), includes a filtered white light source that forms a monochromatic light beam. The white light source includes a halogen lamp (10), a condensing lens (12), a circular aperture (14), a collimator lens (16), a narrow band filter wheel (18), and a second collimator lens (20). The monochromatic light beam generated by this filtered white light source illuminates an entire surface of the wafer (24). Prior to illumination, the wafer (24) is deformed into a reflective condenser. Thus, the monochromatic light beam that illuminates the wafer (24) is reflected off the wafer (24) and collected by an optical scheme that redirects the beam to a detector array (31) of a charge coupled device (CCD) camera (30). The monochromatic light beam incident upon the CCD camera detector array (31) contains an image of an interference fringe pattern that is formed by coherent interactions in the monochromatic light beam as it is reflected within the wafer structure (24). The interference fringe pattern image is displayed on the CCD camera detector array (31) and captured by the CCD camera (30). The captured image is then converted to a map of measured reflectance data by a digitizing circuit (34) and a computer (36). This map of measured reflectance data is then compared to reference reflectance data to generate a map of the thin film layer thickness over a full aperture of the wafer (24).