Substrate alignment apparatus using diffracted and reflected rad

Details Substrate alignment apparatus using diffracted and reflected rad Substrate alignment apparatus using diffracted and reflected rad

1990-05-24

1992-06-02

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

356401, G01B 1126

Patent

active

051189534

ABSTRACT:
An alignment apparatus is provided with a first beam receiving device arranged to receive an interference beam which is produced at a diffraction grating of a substrate as a result of illumination with a pair of beams which intersect each other on the substrate, and a second beam receiving device arranged to receive a reference beam which is produced by the interference between regularly reflected beams of the pair of beams occurring on the substrate, wherein the positional offset of the substrate is obtained on the basis of a comparison between the output signal of the first beam receiving device and the output signal of the second beam receiving device. Since a beam transmitting path for transmitting a measurement beam is substantially common to a beam transmitting path for a reference beam, even if the fluctuations of air occur, both the measurement beam and the reference beam substantially equally reflect the influence of the fluctuations, whereby it is possible to cancel the same.

REFERENCES:
patent: 4656347 (1987-04-01), Une et al.
patent: 4668089 (1987-05-01), Oshida et al.
patent: 5004348 (1991-04-01), Magome

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