Photoresist underlayer composition

A composition comprising a polymer, the polymer comprising:

• repeating units derived from a monomer of Formula A1, Formula A2, or Formula A3,
• repeating units derived from a monomer of Formula B1, Formula B2, Formula B3, or Formula B4,
• and
• Formula B3 Formula B4;
• repeating units derived from a monomer of Formula C1 or Formula C2,
• wherein
• Ar1, Ar2, and Ar3 are each independently an aromatic group;
• R1 is a C1-20 alkyl alcohol, a C1-20 cycloalkyl alcohol, an epoxy with 3 to 12 carbons, or a C5-20 aromatic group with one to six ring carbons substituted with a hydroxy, a glycidyl group, a C1-10 alkyl alcohol, or an epoxy with 3 to 12 carbons;
• R2 is R1 or —OH;
• each of R2a, R2b, and R2c is independently an unsubstituted or substituted C1-20 alkyl, an unsubstituted or substituted C3-20 cycloalkyl, an unsubstituted or substituted C3-20 heterocycloalkyl, or optionally, R2a can join with R2b to form a ring, or R2a can join with R2c of Formulae B2 or B4 to form a ring, or one of R2a, R2b, and R2c is hydrogen;
• L is an unsubstituted or substituted C1-8 alkylene group or an unsubstituted or substituted C2-8 heteroalkylene group;
• L1 is an unsubstituted or substituted C1-8 alkylene group, an unsubstituted or substituted C2-8 heteroalkylene group, an unsubstituted or substituted C6-10 arylene group, or an unsubstituted or substituted C3-10 heteroarylene group;
• L2 is a single bond, —O—, —O(C═O)—, —(C═O)O—, —O(SO2)—, —(SO2)O—, —NH(SO2)—, —(SO2)NH—, —NH(C═O)—, —(C═O)NH—, —SO2—, or —SO—;
• D is a single bond, —O—, —OC(O)—, —NH(C═O)—, or —(C═O)NH—;
• A is an unsubstituted or substituted C1-16 alkylene group, an unsubstituted or substituted C2-16 heteroalkylene group, an unsubstituted or substituted C6-20 arylene group, an unsubstituted or substituted C3-20 heteroarylene group;
• each hal is independently a halogen atom or a C1-4 haloalkyl;
• Ra is a hydrogen atom, a halogen atom, a C1-4 alkyl, or a C1-4 haloalkyl;
• m is 0 or 1, and n is 1 to 12;
• a crosslinker;
• an acid catalyst;
• and a solvent wherein the composition is a photoresist underlayer composition.