A photoresist composition including a polymer is disclosed, wherein the polymer includes at least one monomer having the formula:where R1 represents hydrogen (H), a linear, branched or cyclo alkyl group of 1 to 20 carbons, a semi- or perfluorinated linear, branched or cyclo alkyl group of 1 to 20 carbons or CN; R2 represents an alicyclic group of 5 or more carbon atoms; X represents a methylene, ether, ester, amide or carbonate linkage; R3 represents a linear or branched alkylene group or semi- or perfluorinated linear or branched alkylene group with 1 or more carbon atoms; R4 represents hydrogen (H), methyl (CH3), trifluoromethyl (CF3), difluoromethyl (CHF2), fluoromethyl (CH2F), or a semi- or perflourinated aliphatic group; R5 represents trifluoromethyl (CF3), difluoromethyl (CHF2), fluoromethyl (CH2F), or a semi- or perfluorinated substituted or unsubstituted aliphatic group; n represents an integer of 1 or more; and OR12 represents OH or at least one acid labile group selected from a tertiary alkyl carbonate, a tertiary alkyl ester, a tertiary alkyl ether, an acetal and a ketal. A method of patterning a substrate is also disclosed, wherein the method includes: applying the photoresist composition mentioned above to the substrate to form a film; patternwise exposing the film to an imaging radiation source; and developing areas of the film to form a patterned substrate.