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. 30, 1993
Filed:
Oct. 15, 1990
Robert J Monteverde, Cupertino, CA (US);
Bradley W Scheer, Sunnyvale, CA (US);
VLSI Standards, Inc., Mountain View, CA (US);
Abstract
A standard for calibrating a wafer surface inspection optical scanner, particularly a system for measuring haze. The referene wafer contains sections divided into subsections, each subsection having a quasi-random pattern of light scattering features on an otherwise polished surface of the wafer. The quasi-random pattern of features is formed by creating a random pattern of pits within tiny areas of the subsection and repeating that pattern. The random pattern of pits covers an area less than the area of the spot of a scanning beam used by the wafer surface inspection system. By randomizing the pattern of pits within the scanning beam, the scattered light does not produce interference patterns and thus the scattered light is more isotropic. A direct measurement of the amount of hazel on the reference wafer can be obtained from measuring the amount of scattered light caused by the pits. Since this level of scattering is known beforehand to correspond to a certain level of haze, the wafer surface inspection system can then be calibrated to accurately measure haze on surfaces of non-reference wafers.