Projection optical apparatus and a photographic mask therefor

Details Projection optical apparatus and a photographic mask therefor Projection optical apparatus and a photographic mask therefor

1985-08-23

1987-05-19

Wintercorn, Richard A.

Photocopying

Projection printing and copying cameras

Illumination systems or details

355 43, 355125, G03B 2754

Patent

active

046662928

ABSTRACT:
A projection optical apparatus used for projecting a pattern in the photolithographic operation for semiconductor device fabrication and a photographic mask used with the apparatus. In the projection optical apparatus, the reflected light from the pattern of a mask is utilized in place of the transmitted light through the pattern of the mask for the purpose of projecting the pattern. For this purpose, the projection optical apparatus includes illuminating optical means for projecting an illuminating light to the pattern of the mask and light guide means for directing the illuminating light reflected by the pattern of the mask to a projection optical system. A mask adapted for use with the apparatus contains a pattern composed of two opaque areas which are different in reflectance from each other.

REFERENCES:
patent: 3198097 (1965-08-01), Hine
patent: 3815978 (1974-06-01), Marinace
patent: 4377339 (1983-03-01), Coppock
patent: 4415262 (1983-11-01), Koyama et al.
patent: 4416538 (1983-11-01), Mueller et al.

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