Optical element and exposure apparatus

Abstract

An optical element is used for an exposure apparatus which is configured to illuminate a mask with an exposure light beam for transferring a pattern on the mask onto a substrate through a projection optical system and to interpose a given liquid in a space between a surface of the substrate and the projection optical system. The optical element includes a first anti-dissolution member provided on a surface of a transmissive optical element on the substrate's side of the projection optical system.

1 . An optical element to be used for an exposure apparatus configured to illuminate a mask with an exposure light beam for transferring a pattern on the mask onto a substrate through a projection optical system and to interpose a given liquid in a space between a surface of the substrate and the projection optical system, the optical element comprising:
 a first anti-dissolution member provided on a surface of a transmissive optical element on the substrate's side of the projection optical system, the first anti-dissolution member comprising a film made of an oxide formed by a wet film forming method.   
     
     
         2 . The optical element according to  claim 1 ,
 wherein the first anti-dissolution member comprises a multilayer film having a protective function to protect the optical element against the liquid and an anti-reflection function to prevent reflection of the exposure light beam, the multilayer film comprising a first film formed by a dry film forming method, and a second film made of the oxide formed by the wet film forming method.   
     
     
         3 . The optical element according to  claim 1 ,
 wherein the first anti-dissolution member comprises a multilayer film having a protective function to protect the optical element against the liquid and an anti-reflection function to prevent reflection of the exposure light beam, the multilayer film at least comprising a SiO 2  film formed by the wet film forming method as the outermost layer.   
     
     
         4 . The optical element according to  claim 3 , further comprising:
 a SiO 2  film formed by a dry film forming method, which is to be provided on the optical element's side of the SiO 2  film formed by the wet film forming method.   
     
     
         5 . An exposure apparatus configured to illuminate a mask with an exposure light beam for transferring a pattern on the mask onto a substrate through a projection optical system and to interpose a given liquid in a space between a surface of the substrate and the projection optical system, the exposure apparatus comprising:
 a first anti-dissolution member provided on a surface of a transmissive optical element on the substrate's side of the projection optical system, the first anti-dissolution member comprising a film made of an oxide formed by a wet film forming method.   
     
     
         6 . The exposure apparatus according to  claim 5 ,
 wherein the first anti-dissolution member comprises a multilayer film having a protective function to protect the optical element against the liquid and an anti-reflection function to prevent reflection of the exposure light beam, the multilayer film comprising a first film formed by a dry film forming method, and a second film made of the oxide formed by the wet film forming method.   
     
     
         7 . The exposure apparatus according to  claim 5 ,
 wherein the first anti-dissolution member comprises a multilayer film having a protective function to protect the optical element against the liquid and an anti-reflection function to prevent reflection of the exposure light beam, the multilayer film at least comprising a 8i02 film formed by the wet film forming method as the outermost layer.   
     
     
         8 . The exposure apparatus according to  claim 7 , further comprising:
 a SiO 2  film formed by a dry film forming method, which is to be provided on the optical element is side of the SiO 2  film formed by the wet film forming method.