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:
Apr. 23, 1996
Filed:
Nov. 24, 1993
Hideo Mizutani, Yokohama, JP;
Kesayoshi Amano, Tokyo, JP;
Shinji Wakamoto, Tokyo, JP;
Yuji Imai, Ohmiya, JP;
Nikon Corporation, , JP;
Abstract
An inclination detecting apparatus is for detecting an inclination of a front surface of a transparent wafer placed on a perpendicular to an optical axis of a projection objective in an exposure apparatus. The inclination detecting apparatus includes an illumination optical system and a condenser optical system. The illumination optical system obliquely supplies a collimated beam onto the front surface of the wafer. The condenser optical system can condense the collimated beam supplied from the illumination optical system and reflected by the wafer, and it has a quartered photodetector for receiving the reflected beam and generating a position signal corresponding to a light receiving position. The apparatus further includes a first slit plate and a second slit plate located in the illumination optical system and the condenser optical system respectively. Each of the slit plate has a plurality of slits which are arranged such that light shield portions between slits of the second slit plate can cut off the collimated beam reflected by the back surface of the wafer.