Positive-working photoresist composition

Abstract

Disclosed is a novel chemical-amplification positive-working photoresist composition capable of giving a patterned resist layer with excellent properties such as photosensitivy, pattern resolution, heat resistance and cross sectional profile of the patterned resist layer. The composition is characterized by the use of, as the film-forming resinous component, a hydroxyl-containing resinous ingredient which is a combination of a first resin of which from 30 to 60% of the hydroxyl groups are substituted by acid-dissociable solubility-reducing groups and a second resin of which from 5 to 20% of the hydroxyl groups are substituted by acid-dissociable groups of the same kind as in the first resin in a weight proportion of 1.9 to 9:1.

What is claimed is:  
     
         1 . A chemical-amplification positive-working photoresist composition which comprises, as a uniform solution in an organic solvent: 
 (A) a polyhydroxystyrene-based resinous ingredient of which the hydroxyl groups are partly substituted by acid-dissociable substituent groups capable of being dissociated by interacting with an acid; and    (B) a radiation-sensitive acid-generating compound capable of releasing an acid by irradiation with a radiation, the resinous ingredient as the component (A) being a combination comprising (A1) a first polyhydroxystyrene resin substituted for a part of the hydroxyl groups by acid-dissociable substituent groups and (A2) a second polyhydroxy-styrene resin substituted for a part of the hydroxyl groups by acid-dissociable substituent groups which are the same as in the first polyhydroxystyrene resin (A1), of which the degree of substitution by the substituent groups for a part of the hydroxyl groups in the first polyhydroxystyrene resin (A1) is larger than the degree of substitution in the second polyhydroxystyrene resin (A2) with the proviso that the ratio of the maximum weight-average molecular weight Mw max  to the minimum weight-average molecular weight Mw min  in the first and second polyhydroxystyrene resins (A1) and (A2) is smaller than 1.5.    
     
     
         2 . The chemical-amplification positive-working photoresist composition as claimed in  claim 1  in which the overall degree of substitution in the resinous ingredient as the component (A) for a part of the hydroxyl groups by the acid-dissociable substituent groups is in the range from 5 to 60%.  
     
     
         3 . The chemical-amplification positive-working photoresist composition as claimed in  claim 1  in which the acid-dissociable substituent group is selected from the group consisting of tertiary alkoxycarbonyl groups, tertiary alkyl groups, alkoxyalkyl groups and cyclic ether groups.  
     
     
         4 . The chemical-amplification positive-working photoresist composition as claimed in  claim 3  in which the acid-dissociable substituent group is selected from the group consisting of tert-butoxycarbonyl group, tert-butyl group, tetrahydropyranyl group, tetrahydrofuranyl group, 1-ethoxyethyl group and 1-methoxypropyl group.  
     
     
         5 . The chemical-amplification positive-working photoresist composition as claimed in  claim 1  in which the polyhydroxystyrene-based resinous ingredient as the component (A) is a combination of (A1) a first polyhydroxystyrene resin substituted for from 30 to 60% of the hydroxyl groups by the acid-dissociable substituent groups and (A2) a second polyhydroxystyrene resin substituted for from 5 to 20% of the hydroxyl groups by the acid-dissociable substituent groups.  
     
     
         6 . The chemical-amplification positive-working photoresist composition as claimed in  claim 5  in which the polyhydroxystyrene-based resinous ingredient as the component (A) is a combination of the first and second polyhydroxystyrene resins (A1) and (A2) in a weight proportion in the range from 1:9 to 9:1.  
     
     
         7 . The chemical-amplification positive-working photoresist composition as claimed in  claim 5  in which the polyhydroxystyrene-based resinous ingredient as the component (A) is a combination of (A1) a first polyhydroxystyrene resin substituted for from 35 to 60% of the hydroxyl groups by the acid-dissociable substituent groups and (A2) a second polyhydroxystyrene resin substituted for from 5 to 15% of the hydroxyl groups by the acid-dissociable substituent groups.  
     
     
         8 . The chemical-amplification positive-working photoresist composition as claimed in  claim 7  in which the polyhydroxystyrene-based resinous ingredient as the component (A) is a combination of the first and second polyhydroxystyrene resins (A1) and (A2) in a weight proportion in the range from 4:6 to 1:9.  
     
     
         9 . The chemical-amplification positive-working photoresist composition as claimed in  claim 5  in which the polyhydroxystyrene-based resinous ingredient as the component (A) is a combination of (A1) a first polyhydroxystyrene resin substituted for from 30 to 60% of the hydroxyl groups by tert-butoxycarbonyl groups and (A2) a second polyhydroxystyrene resin substituted for from 5 to 20% of the hydroxyl groups by tert-butoxycarbonyl groups.  
     
     
         10 . The chemical-amplification positive-working photoresist composition as claimed in  claim 1  in which the ratio of the maximum weight-average molecular weight Mw max  to the minimum weight-average molecular weight Mw min  in the first and second polyhydroxystyrene resins (A1) and (A2) is smaller than 1.3.