Resist underlayer film-forming composition containing copolymer resin having heterocyclic ring

A resist underlayer film-forming composition comprising:

• a polymer containing a unit structure of Formula (1):
• (in Formula (1), R1 and R2 each are a substituent of a hydrogen atom on an aromatic ring, and are each independently a halogen group, a nitro group, an amino group, a carboxylic acid group, a hydroxy group, a C1-10 alkyl group, a C2-10 alkenyl group, a C6-40 aryl group, an organic group containing an ether bond, an organic group containing a ketone bond, an organic group containing an ester bond, or a group in which any of these are combined;
• R3 is a hydrogen atom, or a C1-10 alkyl group, a C2-10 alkenyl group, a C6-40 aryl group, an organic group containing an ether bond, an organic group containing a ketone bond, an organic group containing an ester bond, or a group in which any of these are combined;
• R4 is a C6-40 aryl group or a heterocyclic group, and the aryl group and the heterocyclic group each are optionally substituted with a halogen group, a nitro group, an amino group, a C1-10 alkyl group, a C1-10 alkoxy group, a C6-40 aryl group, a formyl group, a carboxy group, a carboxylic acid ester group, or a hydroxy group;
• R5 is a hydrogen atom, a C1-10 alkyl group, a C6-40 aryl group, or a heterocyclic group, and the alkyl group, the aryl group, and the heterocyclic group each are optionally substituted with a halogen group, a nitro group, an amino group, or a hydroxy group, and R4 and R5 optionally form a ring together with a carbon atom bonded to R4 and R5;
• X is an O atom, a S atom, a CH2 group, a C═O group, a CH═CH group, or a CH2—CH2 group;
• n1 and n2 each are an integer of 0 to 3;
• and m1 and m2 each are an integer of 0 to 3).