High numerical aperture ring field projection system for extreme ultraviolet lithography

Abstract

An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first convex mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receive a chief ray at an incidence angle of less than substantially 9°, and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 14°. Four of the six reflecting surfaces have an aspheric departure of less than substantially 12 μm. Five of the six reflecting surfaces have an aspheric departure of less than substantially 12 μm. Each of the six reflecting surfaces has an aspheric departure of less than substantially 16 μm.

Dependencies are inferred from the claim text.