The invention provides a polymer having (a) at least one repeat unit derived from an ethylenically unsaturated compound having at least one fluorine atom covalently attached to an ethylenically unsaturated carbon atom; and (b) at least one repeat unit derived from an ethylenically unsaturated cyclic compound of structure: (I) wherein n is 0, 1, or 2; and R.sup.2 to R.sup.4 are independently H; C.sub.1-C.sub.10 alkyl or alkoxy, optionally substituted by halogen or ether oxygens; or C.sub.6-C.sub.20 aryl. These polymers can be used in making photoresist compositions and coated substrates. ##STR00001##