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. 19, 1987
Filed:
Aug. 23, 1985
Kazunori Imamura, Tokyo, JP;
Yoshio Mori, Kawasaki, JP;
Nippon Kogaku K.K., Tokyo, JP;
Abstract
A projection optical apparatus used for projecting a pattern in the photolithographic operation for semiconductor device fabrication and a photographic mask used with the apparatus. In the projection optical apparatus, the reflected light from the pattern of a mask is utilized in place of the transmitted light through the pattern of the mask for the purpose of projecting the pattern. For this purpose, the projection optical apparatus includes illuminating optical means for projecting an illuminating light to the pattern of the mask and light guide means for directing the illuminating light reflected by the pattern of the mask to a projection optical system. A mask adapted for use with the apparatus contains a pattern composed of two opaque areas which are different in reflectance from each other.