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It is evident from Tables 4 to 7 that the resist compositions within the scope of the invention show improved DOF and CDU and reduced CD shrinkage amounts by PPD (small CD changes), as compared with well-known resist composi› tions. 

Japanese Patent Application No. 2017-148008 is incor› porated herein by reference. 

Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims. 

The invention claimed is: 

1. A resist composition comprising: 

(A) a base resin consisting of recurring units having the formula ( 1) shown below and recurring units having an acid labile group having the formula (2) shown below, and optionally at least one recurring unit selected from the group consisting of recurring units having the formulae (3) to (5) shown below, 

(B) a photoacid generator consisting of a compound having the formula (B-2) shown below, and 

(C) a solvent, 

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wherein RA is hydrogen or methyl, R 1 is a C$_{1}$-C$_{10 }$ straight, branched or cyclic divalent hydrocarbon group in which at least one carbon atom may be substituted by an ether or carbonyl moiety, 

wherein RA is as defined above and X is an acid labile group, 

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