Method of measuring a leveling plane

Details Method of measuring a leveling plane Method of measuring a leveling plane

1994-01-14

1995-12-12

Evans, F. L.

Optics: measuring and testing

By polarized light examination

With light attenuation

250548, 355 77, 355 53, G01B 1100

Patent

active

054754909

ABSTRACT:
In order to measure inclination of a leveling plane with respect to the best image forming plane rapidly at a high accuracy without using a special super-flat wafer, the images of five focus measuring marks are exposed on shot areas partially overlapping with each other, on one hand, in a first exposure area when a focal position is made to coincide with a first focal position by operating a leveling mechanism and, on the other hand, in each of exposure areas when the focal positions are changed gradually. The best focal position is obtained by using an average of the mark lengths of the images of the marks as the mark lengths of the images of marks of measuring points at the upper left corners of the focal positions.

REFERENCES:
patent: 4558949 (1985-12-01), Uehara et al.
patent: 4677301 (1987-06-01), Tanimoto et al.
patent: 4908656 (1990-03-01), Suwa et al.
patent: 4999669 (1991-03-01), Sakamoto et al.
patent: 5101226 (1992-03-01), Beaulieu et al.
patent: 5218415 (1993-06-01), Kawashima
patent: 5323016 (1994-06-01), Yamada et al.

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