Resist underlayer film forming composition for lithography, containing aromatic fused ring-containing resin

A resist underlayer film forming composition used in a lithography process for producing a semiconductor device comprising:

• a polymer containing at least one unit structure represented by Formula (1), optionally at least one unit structure represented by Formula (2), and at least one unit structure represented by Formula (3):
• wherein:
• X represents a hydrogen atom or an aromatic fused ring,
• Y represents an aromatic fused ring, and X and Y may be bonded to each other to form a fused ring,
• R1, R2, R3, R4, R5, R10, R11 and R12 individually represent a hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms,
• R6, R7 and R8 individually represent a hydrogen atom or a chained or cyclic alkyl group having 1 to 10 carbon atoms,
• R9 represents a chained or cyclic alkyl group having 1 to 10 carbon atoms or an aromatic group having 6 to 20 carbon atoms,
• R7 and R8 may be bonded to each other to form a ring,
• M and Q individually represent a direct bond or a linking group,
• n represents an integer of 0 or 1, and
• the unit structure represented by Formula (1) is a unit structure represented by Formula (1-1), (1-2), (1-3), or (1-4):
• or a combination of more than one such polymer,
• in which when a total number of all unit structures constituting the polymer is assumed to be 1.0, a ratio of a number (a) of the at least one unit structure represented by Formula (1), a ratio of a number (b) of the at least one unit structure represented by Formula (2), and a ratio of a number (c) of the at least one unit structure represented by Formula (3) satisfy 0.5≦a≦0.95, 0.2, and 0.05≦c≦0.3.