Photoresist composition for deep ultraviolet lithography

A photoresist composition comprising a photoacid generator and at least one novel polymer comprising at least one unit as described by structure 1,

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• where, either
• (i) R1 is an aliphatic cyclic unit of a polymer, R2 is selected from H, F, (C1-C8)alkyl, (C1-C8)fluoroalkyl, cycloalkyl, cyclofluoroalkyl, and (CR3R4)p(CO)OR5, and R1 is selected from F, H, (C1-C8)alkyl, or a fully or partially fluorinated alkyl, and cyclofluoroalkyl, or
• (ii) R1 and R2 combine to form an aliphatic cyclic unit of a polymer, and R1 is selected from H, H, (C1-C8)alkyl and a fully or partially fluorinated alkyl, and cyclofluoroalkyl, or
• (ii) R1 and Rf combine to form an aliphatic cyclic unit of a polymer, and R2 is selected from H, F, (C1-C8)alkyl, (C1-C8)fluoroalkyl, cycloalkyl, cyclofluoroalkyl, and (CR3R4)p(CO)OR5;
• and,
• R3 and R4 are independently H, F, (C1-C8)alkyl, (C1-C8)fluoroalkyl, cycloalkyl, cyclofluoroalkyl, (CR3R4)p(CO)OR5, R3 and R4 may combine to form an alkylspirocyclic or a fluoroalkylspirocyclic group,
• X is selected from (C1-C8)alkylene, (C1-C8)fluoroalkylene, O(C1-C8)alkylene, O(C1-C8)fluoroalkylene, cycloalkyl and fluorinated cycloalkyl,
• R5is H or an acid labile group, m=0-1, and p=1-4.