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. 05, 1991
Filed:
Oct. 03, 1989
Stanley Stokowski, Danville, CA (US);
David Wolze, San Jose, CA (US);
Armand P Neukermans, Palo Alto, CA (US);
Tencor Instruments, Mountain View, CA (US);
Abstract
Methods for determining the presence or absence of, and the thickness or other spacial extent of, a contaminant layer at each of a plurality of two or more sites on the surface of an electrically conductive material such as a semiconductor, a metal or a metal silicide. The invention uses a change in photoemission current from an illuminated spot on the surface to determine the presence and extent of a contaminant layer at the illuminated site. Compensation is provided for the effects of capacitive current and photovoltaic current. The invention provides a pattern of illumination sites on the conductor surface that can, if desired, cover all points on the surface.