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. 14, 1993
Filed:
Nov. 01, 1991
Akira Tokui, Itami, JP;
Tetsuro Hanawa, Itami, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
An apparatus for inspecting a phase shift mask includes a light source for irradiating a pattern of a phase shift mask including a light shield member and a phase member, a phase difference detector for generating from light transmitted through the phase shift mask a phase signal including the phase difference created by the phase member, a reference signal generator for generating a reference signal, and a calculation section for detecting a defect in the phase member of the phase shift mask by comparing the phase signal with the reference signal. The reference signal may be generated from a reference mask having the same pattern as that of the phase shift pattern or from CAD data for the formation of the pattern of the phase shift mask.