Reflection reduction projection optical system

Details Reflection reduction projection optical system Reflection reduction projection optical system

1992-05-01

1993-10-26

Henry, Jon W.

Optical: systems and elements

Mirror

Plural mirrors or reflecting surfaces

378 34, 355 52, 355 53, G02B 1706, G03B 2753, G21K 500

Patent

active

052571394

ABSTRACT:
A reflection reduction optical system comprises a first convex reflective surface R.sub.1, a second reflective surface R.sub.2, a third convex reflective surface R.sub.3, and a fourth concave reflective surface R.sub.4 to reflect light rays from an object surface. The third convex reflective surface R.sub.3 and the fourth concave reflective surface R.sub.4 are concentrically disposed. At least one of the object surface O and an image surface I is of concave sphere with respect to the reduction projection optical system. For practical use, the object surface is formed in a concave sphere with respect to the reduction projection optical system and the image plane in a plane perpendicular to the optical axis. A mask of concave sphere, which is the object surface O, is rotated during light exposure about a center of curvature C.sub.0 thereof located on the optical axis. A synchronous scan of wafer surface as being as the image surface I is carried out in a direction perpendicular to the optical axis in synchronism with the rotation of mask.

REFERENCES:
patent: 3748015 (1973-07-01), Offner
patent: 4376580 (1983-03-01), Novak et al.
patent: 4685777 (1987-08-01), Hirose
patent: 4747678 (1988-05-01), Shafer et al.
patent: 5063586 (1991-11-01), Jewell et al.
patent: 5153898 (1992-10-01), Suzuki et al.

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