Mirror projection system for a scanning lithographic projection apparatus, and lithographic apparatus comprising such a system

Abstract

A mirror projection system for use in a step-and-scan lithographic projection apparatus in which a mask pattern is repetitively scan-imaged on a number of areas of a substrate by means of a beam of EUV radiation having a circular segment-shaped cross-section. The projection system, which is easier to manufacture at lower cost than a projection system with six or more imaging mirrors, has only five imaging mirrors with a good numerical aperture and an acceptable image-ringfield width. An EUV lithographic projection apparatus provided with the new projection system has a wafer throughput which is approximately 50% higher than that of an apparatus provided with a six-mirror projection system. Moreover, such a lithographic projection has a compact construction.

Dependencies are inferred from the claim text.