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:
Dec. 27, 1983
Filed:
May. 27, 1982
Hans P Kleinknecht, Bergdietikon, CH;
RCA Corporation, New York, NY (US);
Abstract
An automatic photomask alignment system for projection printing includes a monochromatic light source, such as a laser, a series of diffraction patterns which are located on a semiconductor wafer in locations where alignments are to be made, at least one key which is located on a photomask with which the wafer is to be aligned, and a projection lens system. A light beam from the monochromatic light source is directed about the key on the photomask and through the projection lens system onto one of the diffraction patterns on the substrate to provide a pattern of light spots whose intensities at various locations are determined by the relative alignment of the key and the diffraction grating. A step and repeat mechanism is used to move the semiconductor wafer relative to the image of the photomask pattern which is projected onto the wafer while a feedback arrangement, which employs photocells and servo motors for aligning the locations where devices are to be formed on the substrate relative to the photomask, provides the alignment of the projected image with the proper locations for their formation.