Inclination detecting apparatus and method

Details Inclination detecting apparatus and method Inclination detecting apparatus and method

1993-11-24

1996-04-23

Buczinski, Stephen C.

Optics: measuring and testing

Angle measuring or angular axial alignment

Photodetection of inclination from level or vertical

25055937, 356375, 356400, G01B 1126, G01B 1114, G01N 2100

Patent

active

055108920

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.

REFERENCES:
patent: 4477185 (1984-10-01), Berger et al.
patent: 4558949 (1985-12-01), Uehara et al.
patent: 4704020 (1987-11-01), Murakami et al.
patent: 4902900 (1990-02-01), Kamiya et al.

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