Optics: measuring and testing – By alignment in lateral direction – With registration indicia
Patent
1987-07-02
1989-05-30
Anderson, Bruce C.
Optics: measuring and testing
By alignment in lateral direction
With registration indicia
2504911, G01D 1100, G01J 100
Patent
active
048345407
ABSTRACT:
A projection exposure apparatus for projecting a pattern, formed on a reticle, upon a wafer by way of a projection lens system is disclosed. The apparatus includes an alignment system wherein light is projected upon an alignment mark of the wafer by use of the projection lens system, and the light diffracted by an edge of the wafer alignment mark is guidingly directed from between the projection lens system and the wafer to a photoelectric detector without intervention of the projection lens system. From the photodetector, an alignment signal corresponding to the position of the wafer alignment mark is obtained and, on the basis of the alignment mark signal, the wafer and the reticle are brought into a predetermined positional relation. With the disclosed alignment system, the wafer alignment mark can be detected without being affected by a photoresist layer applied to the wafer surface, with the result that the reticle and the wafer can be aligned more accurately.
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Ina Hideki
Suzuki Akiyoshi
Totsuka Masao
Anderson Bruce C.
Canon Kabushiki Kaisha
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