Mask alignment system

Details Mask alignment system Mask alignment system

1984-08-28

1987-03-24

Evans, F. L.

Optics: measuring and testing

By alignment in lateral direction

With registration indicia

G01B 1126

Patent

active

046521348

ABSTRACT:
A system for aligning a semiconductor wafer with a mask bearing a pattern to be formed on the wafer, in which both the wafer and the mask bear an alignment mark, and in which light used for alignment is filtered to transmit only in a selected bandwidth, uses a reflector system to gather light reflected from edges of the alignment mark on the wafer. In order to minimize the effect of erroneous alignment signals from standing waves generated when the alignment signal is reflected from a wafer coated with a layer of photoresist, a second filter is placed in the path of light after it has reflected from the target. This second filter transmits a range of the reflected light which does not produce standing waves.

REFERENCES:
patent: 3718396 (1973-02-01), Hennings
patent: 3988066 (1976-10-01), Suzuki et al.
patent: 4083634 (1978-04-01), Momose et al.
patent: 4315201 (1982-02-01), Suzuki et al.
patent: 4425037 (1984-01-01), Hershel et al.
patent: 4500615 (1985-02-01), Iwai
Chwalow et al., IBM Technical Disclosure Bulletin, vol. 17, No. 3, 8/1974, p. 866.
Harper et al., IBM Technical Disclosure Bulletin, vol. 13, No. 4, 9/1970, p. 1028.

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