Adhesive composition, adhesive sheet, and back grinding method for semiconductor wafer

Abstract

The present invention relates to a pressure-sensitive adhesive composition including a polymer of a monomer mixture containing isobonyl (meth)acrylate, a pressure-sensitive adhesive sheet, and a semiconductor wafer backgrinding method. In the present invention, by using isobonyl (meth)acrylate which is a hard-type monomer and has a low hydrophilic property, a pressure-sensitive adhesive composition having superior releasing and re-releasing properties and wettability with respect to the wafer, and having an excellent wafer-proofing property; a pressure-sensitive adhesive sheet prepared by using the pressure-sensitive adhesive composition; and a backgrinding method using the pressure-sensitive adhesive sheet can be provided.

1 . A pressure-sensitive adhesive composition comprising a polymer of a monomer mixture, containing:
 (meth)acrylic acid ester monomer including isobonyl (meth)acrylate; and   crosslinkable monomer including at least one functional group selected from the group consisting of a hydroxy group, a carboxyl group, and a nitrogen-containing functional group.   
     
     
         2 . The pressure-sensitive adhesive composition according to  claim 1 , wherein the polymer has a glass transition temperature of −50° C. to 15° C. 
     
     
         3 . The pressure-sensitive adhesive composition according to  claim 1 , wherein the polymer has a weight average molecular weight of 50,000 to 700,000. 
     
     
         4 . The pressure-sensitive adhesive composition according to  claim 1 , wherein the (meth)acrylic acid ester monomer further comprises at least one second monomer selected from a group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate and tetradecyl (meth)acrylate. 
     
     
         5 . The pressure-sensitive adhesive composition according to  claim 4 , wherein the (meth)acrylic acid ester monomer comprises 1 to 30 parts by weight of isobonyl (meth)acrylate and 60 to 98.9 parts by weight of the second monomer. 
     
     
         6 . The pressure-sensitive adhesive composition according to  claim 1 , wherein the crosslinkable monomer is one or more selected from a group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethyleneglycol (meth)acrylate, 2-hydroxypropyleneglycol (meth)acrylate, (meth)acrylic acid, 2-(meth)acryloyloxy acetic acid, 3-(meth)acryloyloxy propyl acid, 4-(meth)acryloyloxy butyl acid, acrylic acid dimer, itaconic acid, maleic acid, maleic anhydride, (meth)acryl amide, N-vinyl pyrrolidone, and N-vinyl caprolactam. 
     
     
         7 . The pressure-sensitive adhesive composition according to  claim 1 , wherein the monomer mixture comprises 90 to 99.9 parts by weight of the (meth)acrylic acid ester monomer and 0.1 to 10 parts by weight of the crosslinkable monomer. 
     
     
         8 . The pressure-sensitive adhesive composition according to  claim 1 , wherein the monomer mixture further comprises a compound represented by the Formula 1: 
       
         
           
           
               
               
           
         
         wherein R 1  to R 3  represent independently hydrogen or alkyl; R 4  represents cyano, penyl unsubstituted or substituted with alkyl, acetyloxy, or COR 5 ; and R 5  represents amino or glycidyloxy unsubstituted or substituted with alkyl or alkoxy alkyl. 
       
     
     
         9 . The pressure-sensitive adhesive composition according to  claim 1 , further comprising 0.1 to 10 parts by weight of a crosslinking agent with respect to 100 parts by weight of the polymer. 
     
     
         10 . The pressure-sensitive adhesive composition according to  claim 9 , wherein the crosslinking agent is one or more selected from a group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound. 
     
     
         11 . A pressure-sensitive adhesive sheet comprising:
 a base film; and   a pressure-sensitive adhesive layer that is formed on one or both sides of the base film and contains a curing product of the pressure-sensitive adhesive composition according to  claim 1 .   
     
     
         12 . The pressure-sensitive adhesive sheet according to  claim 11 , wherein the base film is polyethylene film, ethylene-acetic acid vinyl copolymer film, ethylene-alkyl(meth)acrylate copolymer film, ethylene-α-olefin copolymer film, propylene-α-olefin copolymer film, polyolefin film, polyester film, polyvinyl chloride film, polyester elastomer, or urethane film. 
     
     
         13 . The pressure-sensitive adhesive sheet according to  claim 11 , wherein the base film has a thickness of 10 μm to 500 μm. 
     
     
         14 . The pressure-sensitive adhesive sheet according to  claim 11 , wherein the base film has a storage modulus of 1×10 7  Pa to 1×10 9  Pa at a temperature of −10° C. to 100° C. 
     
     
         15 . The pressure-sensitive adhesive sheet according to  claim 11 , wherein the pressure-sensitive adhesive layer has a thickness of 0.5 μm to 50 μm. 
     
     
         16 . The pressure-sensitive adhesive sheet according to  claim 11 , further comprising a release film formed on the pressure-sensitive adhesive layer. 
     
     
         17 . A backgrinding method comprising:
 a first step of adhering the pressure-sensitive adhesive sheet of  claim 11  to a semiconductor wafer; and   a second step of grinding a back side of the semiconductor wafer to which the pressure-sensitive adhesive sheet is adhered.