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:
Jan. 19, 1982
Filed:
Sep. 13, 1979
Thomson-CSF, Paris, FR;
Abstract
The invention relates to the alignment of designs in two near planes, whereby one (the mask) carries a design which is to be reproduced on the second (the pattern). The invention relates to a method for the optical alignment of these two planes using a pair of marks formed by a lens (4) having linear Fresnel zones inscribed on the mask (1) and a reflecting grating (3) of appropriate width inscribed on the pattern (2). The illumination by a parallel beam of monochromatic light of the lens with Fresnel zones produces on the pattern a substantially rectangular illumination spot which, when made to coincide with the line inscribed on the pattern is reflected or transmitted, and supplies a detected intensity maximum or minimum depending on whether the lines reflects more or less than the remainder of the pattern. The invention also relates to an optical alignment apparatus for performing this method. The invention applies to the alignment of lithographic X-ray masks or photographic masks with respect to patterns on which reproduction is to take place.