Positive-working chemical-amplification photoresist composition

Abstract

Disclosed is a positive-working chemical-amplification photoresist composition used in the patterning works in the manufacture of semiconductor devices, with which quite satisfactory patterning of a photoresist layer can be accomplished even on a substrate surface provided with an undercoating film of silicon nitride, phosphosilicate glass, borosilicate glass and the like in contrast to the prior art using a conventional photoresist composition with which satisfactory patterning can hardly be accomplished on such an undercoating film. The photoresist composition comprises, besides a film-forming resin capable of being imparted with increased solubility in an alkaline solution by interacting with an acid and a radiation-sensitive acid-generating compound, a phosphorus-containing oxo acid such as phosphoric acid and phosphonic acid or an ester thereof.

What is claimed is:  
     
         1 . A positive-working chemical-amplification photoresist composition which comprises, as a uniform solution in an organic solvent: 
 (A) 100 parts by weight of a film-forming resinous compound having acid-dissociable solubility-reducing groups in the molecule and capable of being imparted with an increased solubility in an aqueous alkaline solution by interaction with an acid, which resinous compound is a copolymeric resin comprising monomeric units of an ester of acrylic or methacrylic acid;    (B) from 1 to 20 parts by weight of an acid-generating compound which is an onium salt compound having a fluoroalkylsulfonate as the anionic constituent;    (C) from 0.01 to 5 parts by weight of a phosphorus-containing oxo acid, and    (D) an amine selected from the group consisting of secondary amines and tertiary amines, in an amount sufficient to exhibit a quenching effect.    
     
     
         2 . The positive-working chemical-amplification photoresist composition as claimed in  claim 1  in which the phosphorus-containing oxo acid as the component (C) is selected from the group consisting of phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phenylphosphinic acid and phenylphosphonic acid.  
     
     
         3 . The positive-working chemical-amplification photoresist composition as claimed in  claim 1  in which the copolymeric resin as the component (A) consists of from 50 to 85% by moles of the monomeric units of hydroxystyrene, from 10 to 30% by moles of the monomeric units of styrene and from 2 to 20% by moles of the monomeric units of an ester of acrylic acid or methacrylic acid.  
     
     
         4 . The positive-working chemical-amplification photoresist composition as claimed in  claim 3  in which the ester of acrylic or methacrylic acid is a tert-alkyl acrylate or methacrylate.  
     
     
         5 . The positive-working chemical-amplification photoresist composition as claimed in  claim 4  in which the tert-alkyl acrylate or methacrylate is tert-butyl acrylate or methacrylate.  
     
     
         6 . The positive-working chemical-amplification photoresist composition as claimed in  claim 1  in which the amount of the phosphorus-containing oxo acid as the component (C) is in the range from 0.1 to 2.0 parts by weight per 100 parts by weight of the component (A).  
     
     
         7 . The positive-working chemical-amplification photoresist composition according to  claim 1  wherein the amine is triethylamine, tributylamine, dibutylamine or triethanolamine.  
     
     
         8 . A process for forming a patterned resist layer which comprises: 
 a) coating a substrate with a positive-working chemical-amplification photoresist composition which comprises, as a uniform solution in an organic solvent: 
 (A) 100 parts by weight of a film-forming resinous compound having acid-dissociable solubility-reducing groups in the molecule and capable of being imparted with an increased solubility in an aqueous alkaline solution by interaction with an acid, which resinous compound is a copolymeric resin comprising monomeric units of an ester of acrylic or methacrylic acid;  
 (B) from 1 to 20 parts by weight of an acid-generating compound which is an onium salt compound having a fluoroalkylsulfonate as the anionic constituent;  
 (C) from 0.01 to 5 parts by weight of a phosphorus-containing oxo acid, and  
 (D) an amine selected from the group consisting of secondary amines and tertiary amines, in an amount sufficient to exhibit a quenching effect.,  
   b) drying the coated substrate to form a photoresist layer,    c) patternwise exposing the photoresist layer to actinic rays to form said patterned resist layer.    
     
     
         9 . The process according to  claim 8  wherein said actinic rays are from a KrF excimer laser beam of 248 nm.  
     
     
         10 . The process according to  claim 8  wherein said actinic rays are X-rays.  
     
     
         11 . The process according to  claim 8  wherein said actinic rays are electron beams.  
     
     
         12 . The process according to  claim 8  wherein the substrate is a semiconductor wafer.  
     
     
         13 . The process according to  claim 12  wherein the semiconductor wafer comprises silicon.  
     
     
         14 . The process according to  claim 12  wherein the substrate to be coated has an undercoating film containing nitrogen or containing phosphorus and/or boron.  
     
     
         15 . The process according to  claim 14  wherein the undercoating film comprises at least one nitrogen-containing material which is SiN, Si 3 N 4 , SiON or TiN.  
     
     
         16 . The process according to  claim 14  wherein the undercoating comprises at least one phosphorus and/or boron material which is phosphosilicate glass, borosilicate glass or borophosphosilicate glass.  
     
     
         17 . The process according to  claim 8  wherein the phosphorus-containing oxo acid as the component (C) is selected from the group consisting of phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phenylphosphinic acid and phenylphosphonic acid.  
     
     
         18 . The process according to  claim 8  wherein the copolymeric resin as the component (A) consists of from 50 to 85% by moles of the monomeric units of hydroxystyrene, from 10 to 30% by moles of the monomeric units of styrene and from 2 to 20% by moles of the monomeric units of an ester of acrylic acid or methacrylic acid.  
     
     
         19 . The process according to  claim 18  wherein the ester of acrylic or methacrylic acid is a tert-alkyl acrylate or methacrylate.  
     
     
         20 . The process according to  claim 19 , wherein the tert-alkyl acrylate or methacrylate is tert-butyl acrylate or methacrylate.  
     
     
         21 . The process according to  claim 8  wherein the amount of the phosphorus-containing oxo acid as the component (C) is in the range from 0.1 to 2.0 parts by weight per 100 parts by weight of the component (A).  
     
     
         22 . The process according to  claim 8  wherein the amine is triethylamine, tributylamine, dibutylamine or triethanolamine.