Method for correcting the surface form of a mirror

Abstract

A minor reflecting radiation with an operating wavelength of 5-30 nm, includes a substrate and a reflective coating. The reflective coating includes a first group of layers ( 19 ) and a second group ( 5 ) of layers, such that the second group of layers is arranged between the substrate and the first group of layers. The first group and the second group of layers comprise a plurality of first and second layers ( 9, 11 ). The first layers have a refractive index for radiation having the operating wavelength which is greater than a refractive index of the second layers for radiation having the operating wavelength. A correction layer ( 13 ) has a layer thickness variation for correcting the surface form of the minor and is arranged between the second group and the first group of layers. The correction layer contains carbon, sulfur, phosphorus, fluorine or organic compounds thereof, and inorganic metal compounds.

1 . A mirror configured to reflect radiation having an operating wavelength in the range of 5-30 nm, comprising a substrate and a reflective coating,
 wherein the reflective coating comprises a first group of layers and a second group of layers,   wherein the second group of layers is arranged between the substrate and the first group of layers,   wherein the first group and the second group of layers comprise a plurality of first and second layers arranged alternately one above another, wherein the first layers have a refractive index for radiation having the operating wavelength which is greater than a refractive index of the second layers for radiation having the operating wavelength, and   wherein a correction layer having a layer thickness variation for correcting a surface form of the mirror is arranged between the second group and the first group of layers, wherein the correction layer contains at least one of the following:   carbon, sulfur, phosphorus, fluorine or organic compounds based on these elements, and inorganic metal compounds.   
     
     
         2 . The mirror according to  claim 1 , wherein
 the first group of layers comprises a number of layers which is greater than 20.   
     
     
         3 . The mirror according to  claim 1 , wherein
 the second group of layers and the first group of layers are configured to reflect mutually same operating wavelengths.   
     
     
         4 . A projection lens for a microlithography exposure apparatus comprising a mirror as claimed in  claim 1 . 
     
     
         5 . A microlithography projection exposure apparatus comprising a projection lens as claimed in  claim 4 .