Spectral purity filter for multi-layer mirror, lithographic apparatus including such multi-layer mirror, method for enlarging the ratio of desired radiation and undesired radiation, and device manufacturing method

摘要

A lithographic apparatus comprising a support configured to support a patterning device; a substrate table configured to hold a substrate; a projection system configured to project a pattern imparted to a radiation beam by the patterning device onto a target portion of the substrate; and a first multi-layer mirror and a second multi-layer mirror, the first multi-layer mirror and the second multi-layer minor being arranged along a path of the radiation beam, the first multi-layer minor and the second multi-layer mirror each having a reflectivity of at least about 50% in extreme ultra violet wavelength range, and the first multi-layer mirror configured to reduce radiation having wavelengths in a first wavelength range and the second multi-layer minor configured to reduce radiation having wavelengths in a second wavelength range different from the first wavelength range, wherein the first wavelength range and the second wavelength range are outside extreme ultra violet wavelength range.