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:
Nov. 26, 1985
Filed:
Jun. 20, 1983
William H Broadbent, Jr, Sunnyvale, CA (US);
Steve Buchholz, San Jose, CA (US);
Peter Eldredge, Santa Clara, CA (US);
Mark J Wihl, San Jose, CA (US);
KLA Instruments Corporation, Santa Clara, CA (US);
Abstract
An automatic inspection system for inspecting holes in a mask including carriage means 30, illumination means 44, optical means 48, photosensitive detector means 46, and signal processing means 56. The mask 34 to be inspected is positioned by the carriage means in a horizontal plane. The optical means projects a focused image of a portion of the mask onto the photosensitive detector means. Photodiodes in the detector means are responsive to light from the illumination means that is transmitted through the holes in the mask. The signal processing means scans the outputs of the photodiodes and stores in memory a digital representation of the mask. The signal processing means performs inspection measurements and comparison tests. A smoothness checker circuit 240 measures the local radius of curvature of each hole at several places and compares the measurements to predetermined curvature limits to detect nicks and sharp protrusion defects. An area check circuit 246 measures the area of the hole and compares it to predetermined area limits. A diameter check circuit 244 measures the diameter of the hole in two dimensions and compares it to predetermined diameter limits. If either the hole area or the hole diameter is outside their respective limits, a hole size defect is indicated. Means are also provided for locating completely blocked, mispositioned or unintended holes by comparing detected information to a data base.