Immersion exposure process-use resist protection film forming material, composite film, and resist pattern forming method

Abstract

Provided are a material for forming a resist protecting film which is for use in a liquid immersion lithography process and which is formed on a resist film, wherein the material has the following properties of: being transparent with respect to exposure light; having substantially no compatibility with a liquid for liquid immersion lithography; and causing no mixing with the resist film, a composite film comprising a protective film formed from the material and a resist film, and a method for forming a resist pattern using them. These can prevent both the resist film and the liquid used from changing in properties during the liquid immersion lithography, so that a resist pattern with high resolution can be formed using the liquid immersion lithography.

1 . A material for forming a resist protecting film which is for use in a liquid immersion lithography process and which is formed on a resist film, 
 the material having the following properties of:    being transparent with respect to exposure light;    having substantially no compatibility with a liquid for liquid immersion lithography; and    causing no mixing with the resist film.    
   
   
       2 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , wherein the liquid immersion lithography process is of a construction in which the resist film is exposed through the liquid for liquid immersion lithography present at least on the resist film in a path of the lithography exposure light toward the resist film, wherein the liquid has a predetermined thickness and has a refractive index larger than that of air and smaller than that of the resist film, whereby improving the resolution of a resist pattern.  
   
   
       3 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , wherein the liquid for liquid immersion lithography is water substantially comprised of pure water or deionized water.  
   
   
       4 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer comprising (meth)acrylic ester units.  
   
   
       5 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer having dicarboxylic acid anhydride-containing constitutional units.  
   
   
       6 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer having phenolic hydroxyl group-containing constitutional units.  
   
   
       7 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a silsesquioxane resin.  
   
   
       8 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer having α-(hydroxyalkyl)acrylic acid units.  
   
   
       9 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer having dicarboxylic acid monoester units.  
   
   
       10 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , which has the following properties: 
 having substantially no compatibility with pure water or deionized water; and    causing no mixing with the resist film.    
   
   
       11 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 1 , which is a composition comprising at least a fluorine-substituted polymer.  
   
   
       12 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 11 , wherein the fluorine-substituted polymer is comprised of any one of cyclic perfluoroalkyl polyether and chain perfluoroalkyl polyether or both.  
   
   
       13 . The material for forming a resist protecting film for use in a liquid immersion lithography process according to  claim 12 , wherein the composition is obtained by dissolving any one of the cyclic perfluoroalkyl polyether and the chain perfluoroalkyl polyether or both in a fluorine solvent.  
   
   
       14 . A composite film for use in a liquid immersion lithography process, 
 the composite film comprising a protective film and a resist film,    wherein the protective film has the following properties:    being transparent with respect to exposure light;    having substantially no compatibility with a liquid for liquid immersion lithography; and    causing no mixing with the resist film, and    wherein the protective film is formed on the resist film.    
   
   
       15 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the liquid immersion lithography process is of a construction in which the composite film is exposed through the liquid for liquid immersion lithography present at least on the resist film in a path of the lithography exposure light toward the resist film, wherein the liquid has a predetermined thickness and has a refractive index larger than that of air and smaller than that of the resist film, thus improving the resolution of a resist pattern.  
   
   
       16 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the liquid for liquid immersion lithography is water substantially comprised of pure water or deionized water.  
   
   
       17 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the protective film has the following properties: 
 having no compatibility with pure water or deionized water; and    causing no chemical mixing with the resist film.    
   
   
       18 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the protective film is a coating film of a composition comprising at least a fluorine-substituted polymer.  
   
   
       19 . The composite film for liquid immersion lithography process according to  claim 18 , wherein the fluorine-substituted polymer is comprised of any one of cyclic perfluoroalkyl polyether and chain perfluoroalkyl polyether or both.  
   
   
       20 . The composite film for liquid immersion lithography process according to  claim 19 , wherein the composition is obtained by dissolving any one of the cyclic perfluoroalkyl polyether and the chain perfluoroalkyl polyether or both in a fluorine solvent.  
   
   
       21 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer comprising (meth)acrylic ester units.  
   
   
       22 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer having dicarboxylic acid anhydride-containing constitutional units.  
   
   
       23 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer having phenolic hydroxyl group-containing constitutional units.  
   
   
       24 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a silsesquioxane resin.  
   
   
       25 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer having α-(hydroxyalkyl)acrylic acid units.  
   
   
       26 . The composite film for liquid immersion lithography process according to  claim 14 , wherein the resist film is formed from a resist composition comprised of a base polymer which is a polymer having dicarboxylic acid monoester units.  
   
   
       27 . A method for forming a resist pattern using a liquid immersion lithography process, the method comprising: 
 forming a photoresist film on a substrate;    forming, on the resist film, a protective film having the following properties of: being transparent with respect to exposure light, having substantially no compatibility with a liquid for liquid immersion lithography, and causing no mixing with the resist film;    directly placing the liquid for liquid immersion lithography having a predetermined thickness at least on the protective film on the substrate having the resist film and the protective film stacked thereon;    selectively irradiating the resist film with light through the liquid for liquid immersion lithography and the protective film, and optionally subjecting the resultant resist film to heat treatment;    removing the protective film from the resist film irradiated; and    developing the resist film from which the protective film is removed to obtain a resist pattern.    
   
   
       28 . The method for forming a resist pattern according to  claim 27 , wherein the liquid immersion lithography process is of a construction in which the resist film is exposed through the liquid for liquid immersion lithography present at least on the resist film in a ray of the lithography exposure light toward the resist film, wherein the liquid has a predetermined thickness and has a refractive index larger than that of air and smaller than that of the resist film, whereby improving the resolution of a resist pattern.