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:
Jul. 21, 1998
Filed:
Dec. 27, 1995
Kazuhiro Yamashita, Hyogo, JP;
Masahiro Muro, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An overlay measurement pattern, which is formed in a master pattern of a mask, is selectively transferred by exposure processing onto a resist film on a wafer of semiconductor material. This is followed by detecting, by means of a two-beams interference method, a reference position for the overlay measurement pattern formed by the variation in film thickness occurring at an exposed resist region, with performing no development processing. A reference position for an overlay reference pattern, which is pre-formed in the semiconductor wafer, is detected using an interference pattern produced by white light, to detect an overlay difference between the patterns. Since neither a test exposure process nor a development process is needed to be carried out, this results in not only providing a higher throughput rate but also eliminating factors that contribute to degradation of the accuracy of overlay caused by base line stability and mask alignment repeatability. A higher overlay accuracy is achieved accordingly.