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 spectral purity filter for a multi-layer mirror, a lithographic apparatus having the multi-layer mirror, a method for enlarging a ratio between a desired radiation and an undesired radiation, and a device manufacturing method are provided to increase the ratio between an EUV(Extreme UltraViolet) radiation and a DUV(Deep UltraViolet) radiation by using plural multi-layer mirrors. A multi-layer mirror includes a multi-layer stack(102) having plural alternating layers with a multi-layer stack upper-most layer(103) and a spectrum filter upper-most layer(104). The spectrum filter upper-most layer is arranged on a multi-layer stack. A first spectrum purity reinforcing layer(110) contains a first material and has a first layer thickness. An intermediate layer(111) contains a second material and has a second layer thickness. A second spectrum purity reinforcing layer(112) contains a third material and has a third layer thickness. The second spectrum purity reinforcing layer is arranged on the multi-layer stack upper-most layer. The first material is selected from the group consisting of SiN, Si3N4, SiO2, ZnS, Te, diamond, CsI, Se, SiC, amorphous carbon, MgF2, CaF2, TiO2, Ge, PbF2, ZrO2, BaTiO3, LiF, and NaF. The second material contains a material different from the first and third materials. A sum of the first through third layer thicknesses lies between 2.5 and 40nm.