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. 18, 1980
Filed:
Jun. 05, 1978
John P Reekstin, Orange, CA (US);
Sigfried G Plonski, Santa Ana, CA (US);
Addison B Jones, Yorba Linda, CA (US);
Rockwell International Corporation, El Segundo, CA (US);
Abstract
There is provided a technique and apparatus for aligning a mask to a substrate with high precision using Moire fringe effects produced by superimposing diffraction gratings. The gratings comprise first and second patterns of horizontal and vertical lines and spaces, respectively. The first pattern comprises horizontal and vertical lines and spaces of a first width. The second pattern comprises horizontal and vertical lines of a second width which differs from the lines in the first pattern by a small amount .DELTA.. The patterns are superimposed to provide a Moire fringe effect. When alignment occurs, a symmetrical pattern is provided. If misalignment in the X, Y or .theta. coordinate occurs, an assymmetrical or skewed pattern of Moire fringe effects is generated.