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. 30, 1997
Filed:
May. 30, 1995
Norihiro Tarumoto, Tokyo, JP;
Hiroyuki Miyashita, Tokyo, JP;
Yukio Iimura, Tokyo, JP;
Koichi Mikami, Tokyo, JP;
Dai Nippon Printing Co., Ltd., Tokyo, JP;
Abstract
The invention relates to a phase shift photomask in which the peripheral region portion of a phase shift layer is removed by a relatively simple procedure and which has no or little defect and is inexpensive, a blank therefor, and a process for fabricating them. The process includes the steps of forming phase shift layer 23 all over the surface of one side of transparent substrate 21, and immersing only the peripheral region of substrate 21 in etching solution 25 to etch away the peripheral region of phase shift layer 23, whereby phase shift layer 27 is confined within an area smaller than that of substrate 21.