Patent ID: 6081578
Filing Date: 2000-06-27
Classification: G02B,G03F

Abstract:
A projection system for a step-and-scan lithographic projection apparatus, comprising a source of EUV radiation, in which a mask pattern, present in a mask, is imaged on a substrate provided with a layer which is sensitive to EUV radiation, said projection system having a magnification M of -1/4 and a numerical aperture NA of 0.1, and comprising consecutively, from the mask side to the substrate side, a first concave mirror, a convex mirror and a second concave mirror, characterized in that the system has a focal length f of at least +1/2 L, in which L is the total length of the system, and the chief ray of the object beam incident on the first concave mirror is inclined towards the optical axis of the system.