Method and apparatus for projection type mask alignment

Details Method and apparatus for projection type mask alignment Method and apparatus for projection type mask alignment

1980-02-19

1982-12-07

Rosenberger, R. A.

Optics: measuring and testing

By alignment in lateral direction

With registration indicia

356150, G01B 1127, H05K 1300

Patent

active

043623891

ABSTRACT:
A mask alignment method of the projection type is disclosed which is based upon a fact that the exit pupil of a projection lens is actually positioned at a finite distance, and wherein a first wafer alignment pattern including a line segment and a second wafer alignment pattern including another line segment are formed on a wafer in those radial directions from the optical axis of a projection lens which intersect with each other approximately at a right angle. A first mask alignment pattern including a line segment and a second mask alignment pattern including another line segment are formed respectively at those positions on a mask which optically correspond to respective positions of the first and second wafer alignment patterns through the projection lens. The optical image of the first wafer alignment pattern superposed on the optical image of the first mask alignment pattern by the action of the projection lens falls on an image pickup device or element, the optical image of the second wafer alignment pattern superposed on the optical image of the second mask alignment pattern by the action of the projection lens falls on another image pickup device or element, the relative displacement between the wafer and the mask is determined by the video signals delivered from the image pickup devices or elements, and the wafer and the mask are aligned with each other so as to reduce the relative displacement to zero.

REFERENCES:
patent: 3943359 (1976-03-01), Matsumoto et al.
patent: 4103998 (1978-08-01), Nakazawa et al.
patent: 4153371 (1979-05-01), Koizumi et al.
patent: 4170418 (1979-10-01), Aiuchi et al.

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