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:
Jun. 13, 1989
Filed:
Jun. 11, 1987
Norio Uchida, Yokohama, JP;
Yoriyuki Ishibashi, Yokohama, JP;
Ryoichi Hirano, Tokyo, JP;
Masayuki Masuyama, Kumagaya, JP;
Hiroaki Shimozono, Tokyo, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Tokyo Kogaku Kikai Kabushiki Kaisha, Tokyo, JP;
Abstract
According to this invention, a method and apparatus for setting a gap to a predetermined distance between a mask and a wafer facing each other, are arranged as follows. First and second diffraction grating are formed on a mask and a wafer. The first diffraction grating is one-dimensional type and has parallel bars extending in a predetermined direction. The second diffraction grating is one-dimensional type and has parallel bars extending in a direction perpendicular to the predetermined direction. The second diffraction grating may be two-dimensional type having cross-bars. Laser beam is radiated from a light source onto the first diffraction grating. The light beams diffracted and transmitted through the first diffraction grating are transferred to the second diffraction grating. The light beams diffracted and reflected by the second diffraction grating are transferred to the first diffraction grating. The light beams are diffracted and transmitted through the first diffraction grating. Is detected, one of the diffracted light beams which are not oriented along a predetermined. The light beams reflected and diffracted by the surface of the first diffraction grating is transferred only by the prdetermined plane. Therefore, detected and diffracted light beam does not interfere with reflected light beams. The gap between the mask and the wafer can be adjusted and can be set to a predetermined distance.