Chemically amplified negative resist composition and patterning process

Abstract

A chemically amplified negative resist composition comprises a polymer comprising recurring hydroxystyrene units and recurring styrene units having electron withdrawing groups substituted thereon. In forming a pattern having a fine feature size of less than 0.1 μm, the composition exhibits a high resolution in that a resist coating formed from the composition can be processed into such a fine size pattern while the formation of bridges between pattern features is minimized.

1 . A chemically amplified negative resist composition comprising a polymer comprising recurring units having the general formulae (1) and (2): 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are each independently hydrogen or methyl, X is an electron withdrawing group, m is 0 or an integer of 1 to 4, and n is an integer of 1 to 5, said polymer having a weight average molecular weight of 1,000 to 50,000. 
     
     
         2 . The resist composition of  claim 1  wherein the electron withdrawing group represented by X has an active structure directly bonded to the benzene ring, the active structure being at least one member selected from the group consisting of a halogen atom, carbonyl group, nitro group, cyano group, sulfinyl group, and sulfonyl group. 
     
     
         3 . The resist composition of  claim 2  wherein the electron withdrawing group represented by X is at least one member selected from the group consisting of chlorine, bromine, and iodine. 
     
     
         4 . The resist composition of  claim 1  wherein said polymer further comprises recurring units having the general formula (3): 
       
         
           
           
               
               
           
         
       
       wherein R 3  and R 4  are each independently hydrogen, optionally substituted hydroxyl, or halogen, and u is 0 or an integer of 1 to 5. 
     
     
         5 . The resist composition of  claim 1  wherein said polymer has a weight average molecular weight of 2,000 to 8,000. 
     
     
         6 . The resist composition of  claim 1  wherein said polymer has a dispersity Mw/Mn equal to or less than 1.7. 
     
     
         7 . A pattern forming process comprising the steps of:
 applying the resist composition of  claim 1  onto a substrate to form a coating,   heating the coating,   exposing the coating to light, soft x-ray or electron beam,   post-exposure heating the coating, and   developing the coating with an aqueous alkaline solution.   
     
     
         8 . A resist pattern forming process comprising
 providing a substrate having a surface composed mainly of a transition metal compound,   providing a chemically amplified negative resist composition comprising a polymer comprising recurring units having the general formulae (1) and (2):   
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are each independently hydrogen or methyl, X is an electron withdrawing group, m is 0 or an integer of 1 to 4, and n is an integer of 1 to 5, said polymer having a weight average molecular weight of 1,000 to 50,000, and
 forming a resist pattern on the substrate surface using the chemically amplified negative resist composition. 
 
     
     
         9 . The process of  claim 8  wherein the electron withdrawing group represented by X has an active structure directly bonded to the benzene ring, the active structure being at least one member selected from the group consisting of a halogen atom, carbonyl group, nitro group, cyano group, sulfinyl group, and sulfonyl group. 
     
     
         10 . The process of  claim 8  wherein said polymer further comprises recurring units having the general formula (3): 
       
         
           
           
               
               
           
         
       
       wherein R 3  and R 4  are each independently hydrogen, optionally substituted hydroxyl, or halogen, and u is 0 or an integer of 1 to 5. 
     
     
         11 . The process of  claim 8  wherein said transition metal compound comprises at least one transition metal selected from the group consisting of chromium, molybdenum, zirconium, tantalum, tungsten, titanium, and niobium, and optionally, at least one element selected from the group consisting of oxygen, nitrogen and carbon.