Monomer having diol structure, polymer thereof, and negative photoresist composition and pattern forming method using the same background of the invention

Abstract

Disclosed is a negative photoresist which is suitable for use in photolithography using light of 220 nm or shorter like the light from the ArF excimer laser as exposure light, avoids pattern deformation originated from swelling and has a high adhesion strength to the substrate (a micro pattern is hard to be separated from the substrate) in addition to a dry etching resistance and high resolution. A negative photoresist composition contains a polymer having a diol structure having a repeating unit represented by a following formula (6), a crosslinking agent comprised of a compound containing a functional group represented by a following formula (12) and a photoacid generator which generates acid by exposure:

1 . A polymer having a diol structure having a repeating unit represented by a following formula (6):  
       
         
           
           
               
               
           
         
       
       where R 1  is a hydrogen atom or methyl group, R 2  is a C 2 -C 6  alkylene group and x is an alicyclic alkyl group having a diol structure.  
     
     
         2 . The polymer according to  claim 1 , wherein X in said formula (6) is an alicyclic alkyl group having a diol structure represented by a following formula (7), (8), (9) or (10):  
       
         
           
           
               
               
           
         
       
       where n is an integer from 0 to 3, R 3  and R 4  are a hydrogen atom or methyl group,  
       
         
           
           
               
               
           
         
       
       where R 5  is a hydrogen atom or methyl group,  
       
         
           
           
               
               
           
         
       
       where R 6  is a hydrogen atom or methyl group, or  
       
         
           
           
               
               
           
         
       
       where R 7 is a hydrogen atom or methyl group.  
     
     
         3 . The polymer according to  claim 1 , wherein said polymer has a diol structure represented by a following formula (11) and a weight average molecular weight of 1,000 to 50,000:  
       
         
           
           
               
               
           
         
       
       where R 1  and R 2  are the same as those in said formula (6), X is the same as that in any of said formulae (6) to (10), R 8  is a hydrogen atom or methyl group, R 9  is a C 7 -C 18  crosslinked cyclic hydrocarbon group having a carboxyl group, R 10  is a hydrogen atom or methyl group, R 11  is a C 7 -C 13  hydrocarbon group having a hydroxyl group, R 12  is a hydrogen atom or methyl group, R 13  is a hydrogen atom or a C 1 -C 12  hydrocarbon group having a hydroxyl group, and w, x, y and z are arbitrary values satisfying w+x+y+z=1, 0<w≦1, 0≦x<1, 0≦y<1 and 0≦z<1.  
     
     
         4 . The polymer according to  claim 2 , wherein said polymer has a diol structure represented by said formula (11) and a weight average molecular weight of 1,000 to 50,000.