The invention relates to new polymers that comprise units that contain one or more photoacid generator groups and photoresists that contain the polymers. Preferred polymers of the invention are suitable for use in photoresists imaged at short wavelengths such as sub-250 nm or sub-200 nm, particularly 248 nm and 193 nm.

A fluorine-containing compound represented by the formula 1, ##STR00001## where R.sup.1 is a methyl group or trifluoromethyl group, each of R.sup.2 and R.sup.3 is independently a hydrogen atom or a group containing (a) a hydrocarbon group having a straight-chain, branched or ring form and having a carbon atom number of 1-25 or (b) an aromatic hydrocarbon group, the group optionally containing at least one of a fluorine atom, an oxygen atom and a carbonyl bond, l is an integer of from 0 to 2, each of m and n is independently an integer of 1-5 to satisfy an expression of m+n6, and when at least one of R.sup.1, R.sup.2 and R.sup.3 is in a plural number, the at least one of R.sup.1, R.sup.2 and R.sup.3 may be identical with or different from each other.