Automatic photomask alignment system for projection printing

Details Automatic photomask alignment system for projection printing Automatic photomask alignment system for projection printing

1982-05-27

1983-12-27

Punter, William H.

Optics: measuring and testing

By dispersed light spectroscopy

Utilizing a spectrometer

356400, G01B 1126, G01B 902

Patent

active

044227639

ABSTRACT:
An automatic photomask alignment system for projection printing includes a monochromatic light source, such as a laser, a series of diffraction patterns which are located on a semiconductor wafer in locations where alignments are to be made, at least one key which is located on a photomask with which the wafer is to be aligned, and a projection lens system. A light beam from the monochromatic light source is directed about the key on the photomask and through the projection lens system onto one of the diffraction patterns on the substrate to provide a pattern of light spots whose intensities at various locations are determined by the relative alignment of the key and the diffraction grating. A step and repeat mechanism is used to move the semiconductor wafer relative to the image of the photomask pattern which is projected onto the wafer while a feedback arrangement, which employs photocells and servo motors for aligning the locations where devices are to be formed on the substrate relative to the photomask, provides the alignment of the projected image with the proper locations for their formation.

REFERENCES:
patent: 3542469 (1970-11-01), Hennings et al.
patent: 3718396 (1973-02-01), Hennings
patent: 3853398 (1974-12-01), Kano
patent: 4025197 (1977-05-01), Thompson
patent: 4037969 (1977-07-01), Feldman et al.
patent: 4052603 (1977-10-01), Karlson
patent: 4153371 (1979-05-01), Koizumi et al.
patent: 4200395 (1982-04-01), Smith et al.
patent: 4211489 (1980-07-01), Kleinknecht et al.
patent: 4251160 (1981-02-01), Bouwhuis et al.

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