Patent ID: 6233042
Filing Date: 2001-05-15
Classification: G03F

Abstract:
A projection exposure apparatus, comprising:a projection optical system for performing a projection exposure process by projecting a pattern of a first object onto a second object;a correcting mechanism for changing an optical characteristic of said projection optical system;positional information detecting means for detecting a relative positional relationship between first and second marks, which are disposed at different positions, wherein said positional information detecting means is operable during the projection exposure process and detects the first mark with the use of said projection optical system, and detects the second mark without the use of said projection optical system;discriminating means operable, after the detection of the relative positional relationship by said positional information detecting means is repeated at a predetermined time interval or successively, to discriminate a relation between first positional information obtained as a result of detection of the first mark and second positional information obtained as a result of detection of the second mark made by said positional information detecting means; andactuating means for actuating said correcting mechanism on the basis of the discrimination made by said discriminating means, to change the optical characteristic of said projection optical system.