Polymer, resist composition including the same, and method of forming pattern using the resist composition

A polymer comprising:

• at least one of a first repeating unit represented by Formula 1 or a second repeating unit represented by Formula 2, and being free of a repeating unit of which a structure changes by an acid:
• wherein, in Formulae 1 and 2,
• R11 and R21 are each independently hydrogen, deuterium, halogen, a C1-C6 linear or branched alkyl group, or a halogenated C1-C6 linear or branched alkyl group;
• R12 to R14 and R22 to R24 are each independently hydrogen, deuterium, halogen, or a linear, branched, or cyclic monovalent C1-C20 hydrocarbon group optionally containing a heteroatom;
• b12 and b22 are each independently integers of 1 to 4;
• R15 and R16 are each independently a linear, branched, or cyclic monovalent C1-C20 hydrocarbon group optionally containing a heteroatom, and R15 and R16 optionally bond together to form a ring;
• X− is a counter ion;
• Y is at least one of a halogen, R18SO3, R18CO2, R18PO4, or NO3;
• R18 is a linear, branched, or cyclic monovalent C1-C20 hydrocarbon group optionally containing a heteroatom;
• and
• * and *′ are each a bonding site with a neighboring atom.