Exposure apparatus

Details Exposure apparatus Exposure apparatus

1997-02-14

1998-05-26

Nelms, David C.

Optics: measuring and testing

By alignment in lateral direction

With light detector

356401, G01B 1100

Patent

active

057575053

ABSTRACT:
In order to measure an image formation characteristic of a projection optical system directly and continuously without using a substrate to be replaced during a step for exposure a reticle, a wafer or the like, a reference unit, on which a reference mark is formed, is disposed between the projection optical system and the wafer. In a measuring optical system, diffracted light obtained by irradiating laser beam onto a diffraction grating on a measuring reference plate is irradiated onto a reference mark on the reference unit through a modulator and the projection optical system. Interference light generated from the reference mark is received by a photoelectric sensor through the projection optical system. A variation quantity of a focus position of the projection optical system is obtained from a phase difference of a detection signals output from the photoelectric sensor. A variation quantity of a projection magnification is obtained from an average of the phases of the detection signals.

REFERENCES:
patent: 4870289 (1989-09-01), Sato et al.
patent: 4870452 (1989-09-01), Tanimoto et al.
patent: 5572288 (1996-11-01), Mizutani

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