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:
May. 30, 1995
Filed:
Aug. 05, 1993
Hiroshi Mohri, Tokyo, JP;
Keiji Hashimoto, Tokyo, JP;
Masahiro Takahashi, Tokyo, JP;
Wataru Goto, Tokyo, JP;
Yukio Iimura, Tokyo, JP;
Dai Nippon Printing Co., Ltd., Tokyo, JP;
Abstract
A phase shift photomask and a photomask blank used to produce the same. A dry etching stopper layer, which is disposed between a substrate and a light-shielding layer or between the substrate and a phase shifter layer, is made of either a film mainly composed of tin oxide nitride, which has high etching selectivity and high permeability, or an alumina film formed by sputtering, followed by heat treatment carried out in an oxidizing atmosphere, thereby enabling the required overetching to be satisfactorily performed during etching of the phase shifter layer, and thus making it possible to effect precise phase control. In addition, it is possible to eliminate the occurrence of an in-plane transmittance distribution.