Lithographic apparatus and device manufacturing method

Abstract

To improve the resolution of lithographic apparatus, a flexible member is provided between the projection system and the substrate. The flexible member may be filled with a fluid of a known refractive index. The flexible member may be in contact with both the projection system and the substrate.

1 . A lithographic projection apparatus comprising: 
 an illumination system arranged to condition a radiation beam;    a support structure configured to hold a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section;    a substrate table configured to hold a substrate;    a projection system arranged to project the patterned radiation beam onto a target portion of the substrate; and    a flexible member arranged between the projection system and the substrate, the flexible member having a refractive index higher than air.    
   
   
       2 . A lithographic projection apparatus according to  claim 1 , wherein the flexible member is a sack filled with fluid.  
   
   
       3 . A lithographic projection apparatus according to  claim 2 , wherein the sack is closed to the environment.  
   
   
       4 . A lithographic projection apparatus according to  claim 2 , wherein the sack comprises Teflon, a fluorinated hydrocarbon polymer or polyflouride.  
   
   
       5 . A lithographic projection apparatus according to  claim 2 , wherein the sack has a thickness of 1 μm.  
   
   
       6 . A lithographic projection apparatus according to  claim 2 , wherein the fluid is a liquid.  
   
   
       7 . A lithographic projection apparatus according to  claim 6 , wherein the liquid is water.  
   
   
       8 . A lithographic projection apparatus according to  claim 1 , wherein a part of the flexible member is transmissive to the radiation beam.  
   
   
       9 . A device manufacturing method comprising: 
 projecting a patterned radiation beam through a flexible member onto a target portion of the substrate, the flexible member arranged between a projection system of a lithographic apparatus used for projecting the patterned radiation beam and the substrate.    
   
   
       10 . A method according to  claim 9 , wherein the flexible member is a sack filled with fluid.  
   
   
       11 . A method according to  claim 10 , wherein the sack is closed to the environment.  
   
   
       12 . A method according to  claim 10 , wherein the sack comprises Teflon, a fluorinated hydrocarbon polymer or polyflouride.  
   
   
       13 . A method according to  claim 10 , wherein the sack has a thickness of 1 μm.  
   
   
       14 . A method according to  claim 10 , wherein the fluid is a liquid.  
   
   
       15 . A method according to  claim 14 , wherein the liquid is water.  
   
   
       16 . A method according to  claim 9 , wherein the flexible member is in contact with a final element of the projection system.  
   
   
       17 . A method according to  claim 9 , wherein the flexible member is in contact with the substrate.  
   
   
       18 . A method according to  claim 9 , wherein a part of the flexible member is transmissive to the patterned radiation beam.