Apparatus and method for recovering fluid for immersion lithography

Abstract

Apparatus and methods recover a fluid from an immersion area formed in a gap between a projection system and an object of exposure in an immersion lithography system. Liquid is supplied through a supply inlet. A porous member is disposed adjacent to a space. The porous member includes a first portion and a second portion. A recovery capability to remove the supplied liquid from the space through the first portion is different from a recovery capability to remove the supplied liquid from the space through the second portion.

1 . An apparatus for a liquid immersion lithography system in which a substrate is exposed to an irradiation beam through a liquid, the apparatus comprising:
 a supply inlet through which a liquid is supplied; and   a porous member disposed adjacent to a space, the porous member including a first portion and a second portion, a recovery capability to remove the supplied liquid from the space through the first portion being different from a recovery capability to remove the supplied liquid from the space through the second portion.   
   
   
       2 . The apparatus of  claim 1 , wherein the first portion of the porous member is disposed on first and second opposite sides of an immersion area that is formed by the liquid in the space, and the second portion of the porous member is disposed on third and fourth opposite sides of the immersion area. 
   
   
       3 . The apparatus of  claim 2 , wherein the porous member encircles the immersion area. 
   
   
       4 . The apparatus of  claim 1 , wherein a shape of the first portion of the porous member is the same as a shape of the second portion of the porous member. 
   
   
       5 . The apparatus of  claim 1 , wherein a shape of the first portion of the porous member is different from a shape of the second portion of the porous member. 
   
   
       6 . The apparatus of  claim 1 , wherein:
 the liquid immersion lithography system is a scanning exposure system that moves the substrate in a scanning direction during exposure of the substrate to the irradiation beam;   the first portion of the porous member is disposed on first and second opposite sides of an immersion area that is formed by the liquid in the space, the first and second opposite sides each extending in a direction that intersects the scanning direction; and   the second portion of the porous member is disposed on third and fourth opposite sides of the immersion area, the third and fourth opposite sides each extending in a direction that is parallel to the scanning direction.   
   
   
       7 . The apparatus of  claim 1 , wherein the porous member is one of a mesh, a porous material and a member having etched holes therein. 
   
   
       8 . The apparatus of  claim 1 , wherein the porous member is disposed on a radially outer portion of the apparatus, and a radially inner portion of the apparatus includes the supply inlet. 
   
   
       9 . The apparatus of  claim 1 , wherein the first and second portions of the porous member have a same porosity. 
   
   
       10 . The apparatus of  claim 1 , wherein the first and second portions of the porous member have an identical structure. 
   
   
       11 . The apparatus of  claim 1 , wherein a first low pressure is supplied to the first portion of the porous member, and a second low pressure, different from the first low pressure, is supplied to the second portion of the porous member, so that the recovery capability to remove the supplied liquid from the space through the first portion is different from the recovery capability to remove the supplied liquid from the space through the second portion. 
   
   
       12 . The apparatus of  claim 11 , wherein the first and second low pressures each maintain a pressure at a surface of the porous member below a bubble point of the porous member so that gas does not flow through the first and second portions of the porous member. 
   
   
       13 . An immersion lithography system for transferring an image onto a substrate, the immersion lithography system comprising:
 a projection system;   a stage which holds the substrate, the projection system forms the image on the substrate held by the stage; and   the apparatus of  claim 1  for supplying an immersion liquid through the supply inlet to a gap between the projection system and the substrate held by the stage and for recovering the immersion liquid from the gap through the porous member.   
   
   
       14 . A process for manufacturing a device comprising the steps of providing a substrate and transferring an image onto the substrate utilizing the immersion lithography system of  claim 13 . 
   
   
       15 . A method of supplying and recovering liquid in a liquid immersion lithography system in which a substrate is exposed to an irradiation beam through the liquid, the method comprising:
 supplying the liquid to a space through a supply inlet; and   recovering the liquid from the space through a porous member disposed adjacent to the space, the porous member including a first portion and a second portion, a recovery capability to remove the supplied liquid from the space through the first portion being different from a recovery capability to remove the supplied liquid from the space through the second portion.   
   
   
       16 . The method of  claim 15 , wherein the first portion of the porous member is disposed on first and second opposite sides of an immersion area that is formed by the liquid in the space, and the second portion of the porous member is disposed on third and fourth opposite sides of the immersion area. 
   
   
       17 . The method of  claim 16 , wherein the porous member encircles the immersion area. 
   
   
       18 . The method of  claim 15 , wherein a shape of the first portion of the porous member is the same as a shape of the second portion of the porous member. 
   
   
       19 . The method of  claim 15 , wherein a shape of the first portion of the porous member is different from a shape of the second portion of the porous member. 
   
   
       20 . The method of  claim 15 , wherein:
 the liquid immersion lithography system is a scanning exposure system that moves the substrate in a scanning direction during exposure of the substrate to the irradiation beam;   the first portion of the porous member is disposed on first and second opposite sides of an immersion area that is formed by the liquid in the space, the first and second opposite sides each extending in a direction that intersects the scanning direction; and   the second portion of the porous member is disposed on third and fourth opposite sides of the immersion area, the third and fourth opposite sides each extending in a direction that is parallel to the scanning direction.   
   
   
       21 . The method of  claim 15 , wherein the porous member is one of a mesh, a porous material and a member having etched holes therein. 
   
   
       22 . The method of  claim 15 , wherein the porous member is disposed on a radially outer portion of the apparatus, and a radially inner portion of the apparatus includes the supply inlet. 
   
   
       23 . The method of  claim 15 , wherein the first and second portions of the porous member have a same porosity. 
   
   
       24 . The method of  claim 15 , wherein the first and second portions of the porous member have an identical structure. 
   
   
       25 . The method of  claim 15 , wherein a first low pressure is supplied to the first portion of the porous member, and a second low pressure, different from the first low pressure, is supplied to the second portion of the porous member, so that the recovery capability to remove the supplied liquid from the space through the first portion is different from the recovery capability to remove the supplied liquid from the space through the second portion. 
   
   
       26 . The method of  claim 25 , wherein the first and second low pressures each maintain a pressure at a surface of the porous member below a bubble point of the porous member so that gas does not flow through the first and second portions of the porous member.