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:
Mar. 03, 1998
Filed:
Feb. 28, 1996
Toshifumi Yokoyama, Tokyo, JP;
Hiroyuki Miyashita, Tokyo, JP;
Dai Nippon Printing Co., Ltd., Tokyo, JP;
Abstract
A phase shift photomask capable of being produced by dry etching with adequate in-plane uniformity of pattern dimension even if there is a large difference in exposed area ratio between different areas on the mask. In a phase shift photomask having an area provided with a phase shift layer which practically shifts the phase relative to another area, a dummy etching pattern (13) for dry etch rate correction is provided in an area other than a pattern exposure area (9 and 10), or a dummy etching pattern for dry etch rate correction having a size less than the limit of resolution attained by transfer is provided in the pattern exposure area, thereby reducing the etch rate nonuniformity due to the pattern density variation in the process of dry etching the phase shift photomask, and thus providing a phase shift photomask of high accuracy.