Patent ID: 6303900
Filing Date: 2001-10-16
Classification: B23K,B41J

Abstract:
An apparatus comprising:an illumination optical system for illuminating a mask with coherent light emitted from a light source; anda projection optical system for projecting an image of a pattern of the mask onto a substrate with the coherent light, wherein said projection optical system comprises a first optical member and a second optical member,wherein diffracted light rays of different orders generated by the mask are transmitted through the first and second optical members, andwherein the second optical member, which is positioned at an area where the diffracted light rays of different orders generated by the mask are superimposed, employs an optical material having a smaller variation in an optical path length arising from light absorption than an optical material of the first optical member, which is positioned at an area where the diffracted light rays of different orders are not superimposed.