Microlithographic projection exposure apparatus

Abstract

A microlithographic projection exposure apparatus contains an illumination system ( 12 ) for generating projection light ( 13 ) and a projection lens ( 20; 220; 320; 420; 520; 620; 720; 820; 920; 1020; 1120 ) with which a reticle ( 24 ) that is capable of being arranged in an object plane ( 22 ) of the projection lens can be imaged onto a light-sensitive layer ( 26 ) that is capable of being arranged in an image plane ( 28 ) of the projection lens. The projection lens is designed for immersion mode, in which a final lens element (L 5; L 205; L 605; L 705; L 805; L 905; L 1005; L 1105 ) of the projection lens on the image side is immersed in an immersion liquid ( 34; 334 a; 434 a; 534 a ). A terminating element ( 44; 244; 444; 544; 644; 744; 844; 944; 1044; 1144 ) that is transparent in respect of the projection light ( 13 ) is fastened between the final lens element on the image side and the light-sensitive layer.

1 - 17 . (canceled) 
     
     
         18 . A projection lens configured to be used with an immersion liquid, the projection lens comprising:
 a plurality of optical elements comprising a last optical element configured to be closest to the immersion liquid during use of the projection lens; and   a protective layer supported by the last optical element,   wherein:
 the last optical element is corrodible by the immersion liquid; and 
 the protective layer is configured to protect the last optical element from corrosion by the immersion liquid. 
   
     
     
         19 . The projection lens of  claim 18 , further comprising the immersion liquid. 
     
     
         20 . A projection lens configured to be used with an immersion liquid, the projection lens comprising:
 a plurality of optical elements comprising a last optical element configured to be closest to the immersion liquid during use of the projection lens; and   a protective layer evaporation coated on the last optical element.   
     
     
         21 . The projection lens of  claim 20 , further comprising the immersion liquid. 
     
     
         22 . A projection lens configured to be used with an immersion liquid, the projection lens comprising:
 a plurality of optical elements configured to direct radiation along a path from an object plane to an image plane, the plurality of optical elements comprising a last optical element before the image plane along the path,   wherein:
 a surface of the last optical element is configured to be in contact with the immersion liquid during use of the projection lens; and 
 during use of the projection lens, discharging of the immersion liquid from a region between the image plane and the surface of the last optical element is hindered solely by cohesive forces between the immersion liquid and the surface of the last optical element. 
   
     
     
         23 . The projection lens of  claim 22 , further comprising the immersion liquid. 
     
     
         24 . A projection lens configured to be used with an immersion liquid, the projection lens comprising:
 a plurality of optical elements configured to direct radiation along a path from an object plane to an image plane, the plurality of optical elements comprising a last optical element configured to be closest to the immersion liquid during use of the projection lens; and   an inlet configured so that, during use of the projection lens, the inlet provides a gas to a region adjacent the immersion liquid,   wherein the gas comprises a gaseous form of the immersion liquid.   
     
     
         25 . The projection lens of  claim 24 , further comprising a body configured to at least partially enclose the immersion liquid, wherein the inlet is configured so that, during use of the projection lens, the inlet provides the gas to an interior of the body. 
     
     
         26 . The projection lens of  claim 25 , wherein the body comprises a container. 
     
     
         27 . The projection lens of  claim 25 , further comprising the immersion liquid. 
     
     
         28 . The projection lens of  claim 24 , further comprising the immersion liquid. 
     
     
         29 . A method of using a system that comprises a projection lens and an immersion liquid, the projection lens comprising a plurality of optical elements including a last optical element which is closest to the immersion liquid, the method comprising:
 using the projection lens to direct radiation from an object plane to an image plane; and   exposing the immersion liquid to a gas, wherein the gas comprises a gaseous form of the immersion liquid.   
     
     
         30 . A system, comprising:
 a projection lens, comprising:
 a housing; and 
 a plurality of optical elements in the housing; and 
   an immersion liquid,   wherein:
 the plurality of optical elements are configured to direct radiation from an object field to an image field; 
 the immersion liquid is between the projection lens and the image field; and 
 the system is configured so that, adjacent an image field side of the projection lens, there is a peripheral gap configured to adjust a level of immersion liquid in the system. 
   
     
     
         31 . The system of  claim 30 , further comprising the immersion liquid. 
     
     
         32 . A method of using a system that comprises a projection lens and an immersion liquid, the projection lens comprising a plurality of optical elements configured to direct radiation from an object plane to an image plane, the immersion liquid being between the plurality of optical elements and the image plane, the method comprising:
 using the plurality of optical elements to direct radiation from the object plane to the image plane; and   adjusting a level of the immersion liquid via a peripheral gap at an image side exposing the immersion liquid to a gas.   
     
     
         33 . A system, comprising:
 a projection lens, comprising:
 a housing; and 
 a plurality of optical elements in the housing; 
   an immersion liquid; and   at least one gas discharge device configured to direct a gas toward an outer surface of the immersion liquid,   wherein:
 the plurality of optical elements are configured to direct radiation from an object field to an image field; and 
 the immersion liquid is between the projection lens and the image field. 
   
     
     
         34 . The system of  claim 33 , wherein the system comprises a plurality of gas discharge devices configured to direct a gas toward an outer surface of the immersion liquid. 
     
     
         35 . The system of  claim 33 , wherein:
 a plurality of optical elements comprises a last optical element configured to be closest to the immersion liquid during use of the projection lens; and   the outer surface of the immersion liquid is between the last optical element and the image plane.   
     
     
         36 . The system of  claim 33 , wherein the outer surface of the immersion liquid defines an outer peripheral surface of the immersion liquid. 
     
     
         37 . The system of  claim 33 , further comprising the immersion liquid.