Over-coating agent for forming fine patterns and a method of forming fine patterns using such agent

Abstract

It is disclosed an over-coating agent for forming fine-line patterns which is applied to cover a substrate having thereon photoresist patterns and allowed to shrink under heat so that the spacing between adjacent photoresist patterns is lessened, further characterized by comprising a water-soluble polymer which contains at least methacrylic acid and/or methyl methacrylate as the constitutive monomer thereof. Also disclosed is a method of forming fine-line patterns using the over-coating agent. The advantages of the invention are that the exposure margin is large, that the dimension control of photoresist patterns can be reflected on the dimension controllability in forming fine-line patterns, that the dimension control and planning of forming fine trace patterns after treatment for thermal shrinkage can be attained with ease in the stage of photoresist patterning, that the original photoresist pattern profile can be kept as such and the top of the photoresist pattern is not rounded after thermal shrinkage, that the degree of thermal shrinkage of the over-coating agent is large and thus the agent is effective in forming fine-line patterns.

1 . An over-coating agent for forming fine patterns which is applied to cover a substrate having photoresist patterns thereon and allowed to shrink under heat so that the spacing between adjacent photoresist patterns is lessened, further characterized by comprising a water-soluble polymer which contains at least methacrylic acid and/or methyl methacrylate as the constitutive monomer thereof.  
   
   
       2 . The over-coating agent for forming fine patterns according to  claim 1 , further comprising an aliphatic amine.  
   
   
       3 . The over-coating agent for forming fine patterns according to  claim 2 , wherein the aliphatic amine is triethylamine.  
   
   
       4 . The over-coating agent for forming fine patterns according to  claim 1 , wherein the water-soluble polymer is a copolymer of methacrylic acid and/or methyl methacrylate with at least one monomer selected from those constituting alkylene glycol-based polymers, cellulosic derivatives, vinylic polymers, acrylic polymers, urea-based polymers, epoxy polymers, amide-based polymers and melamine-based polymers (in which the monomers to constitute acrylic polymers do not include methacrylic acid and methyl methacrylate).  
   
   
       5 . The over-coating agent for forming fine patterns according to  claim 4 , wherein the water-soluble polymer contains methacrylic acid and/or methyl methacrylate in a ratio of 60-99 mass % of the polymer.  
   
   
       6 . The over-coating agent for forming fine patterns according to  claim 1 , wherein the water-soluble polymer is a copolymer or a mixed resin of polymethacrylic acid and/or polymethyl methacrylate with at least one polymer selected from alkylene glycol-based polymers, cellulosic derivatives, vinylic polymers, acrylic polymers (excluding polymethacrylic acid and polymethyl methacrylate), urea-based polymers, epoxy polymers, amide-based polymers and melamine-based polymers.  
   
   
       7 . The over-coating agent for forming fine patterns according to  claim 6 , wherein the water-soluble polymer contains polymethacrylic acid and/or polymethyl methacrylate in a ratio of 60-99 mass % of the polymer.  
   
   
       8 . The over-coating agent for forming fine patterns according to  claim 1 , wherein the water-soluble polymer is a copolymer of methacrylic acid and/or methyl methacrylate, acrylic acid and/or methyl acrylate, and at least one monomer selected from polymers constituting alkylene glycol-based polymers, cellulosic derivatives, vinylic polymers, acrylic polymers, urea-based polymers, epoxy polymers, amide-based polymers and melamine-based polymers (in which the monomers to constitute acrylic polymers do not include methacrylic acid, methyl methacrylate, acrylic acid and methyl acrylate).  
   
   
       9 . The over-coating agent for forming fine patterns according to  claim 8 , wherein the water-soluble polymer contains methacrylic acid and/or methyl methacrylate in a ratio of 5-35 mass % of the polymer, and acrylic acid and/or methyl acrylate in a ratio of 35-75 mass % of the polymer.  
   
   
       10 . The over-coating agent for forming fine patterns according to  claim 1 , wherein the water-soluble polymer is a copolymer or a mixed resin of polymethacrylic acid and/or polymethyl methacrylate, polyacrylic acid and/or polymethyl acrylate, and at least one polymer selected from alkylene glycol-based polymers, cellulosic derivatives, vinylic polymers, acrylic polymers (not including polymethacrylic acid, polymethyl methacrylate, polyacrylic acid and polymethyl acrylate), urea-based polymers, epoxy polymers, amide-based polymers and melamine-based polymers.  
   
   
       11 . The over-coating agent for forming fine patterns according to  claim 10 , wherein the water-soluble polymer contains polymethacrylic acid and/or polymethyl methacrylate in a ratio of 5-35 mass % of the polymer, and polyacrylic acid and/or polymethyl acrylate in a ratio of 35-75 mass % of the polymer.  
   
   
       12 . The over-coating agent for forming fine patterns according to  claim 1 , which is an aqueous solution having a concentration of 3-50 mass %.  
   
   
       13 . A method of forming fine patterns comprising the steps of covering a substrate having thereon photoresist patterns with the over-coating agent for forming fine patterns according to  claim 1 , then applying heat treatment to shrink the applied over-coating agent under the action of heat so that the spacing between adjacent photoresist patterns is lessened, and subsequently removing the applied film of the over-coating agent substantially completely.  
   
   
       14 . The method of forming fine patterns according to  claim 13 , wherein the heat treatment is performed by heating the substrate at a temperature that does not cause thermal fluidizing of the photoresist patterns on the substrate.