Position detecting apparatus and projection exposure apparatus

Details Position detecting apparatus and projection exposure apparatus Position detecting apparatus and projection exposure apparatus

1994-12-21

1997-11-04

Grimley, Arthur T.

Photocopying

Projection printing and copying cameras

Illumination systems or details

355 53, 355 55, 355 67, 250548, 396120, H01L 27027, G03B 2772

Patent

active

056845693

ABSTRACT:
In a position detecting apparatus, according to this invention, a convexly and concavely patterned wafer mark is imaged on an image pickup surface via an imaging optical system, and the image on the image pickup surface is detected. The position detecting apparatus defocuses the average surface of the wafer mark from the optimum focusing surface depending on the pitch and difference in level of the wafer mark, etc., in the direction of the optical axis of the imaging optical system, and varies an illumination .sigma. value definded as the ratio of the numerical aperture of the illumination optical system and the numerical aperture of the imaging optical system. Then the position detecting apparatus provides lights from the wafer mark to the image pickup surface with rotation-symmetric wave aberration to allow the resulting image to have the highest contrast for positional detection.

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