Patent ID: 8709701

Claim:
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) 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, R 1 , R 2 , R 10 , R 11 and R 12 individually represent a hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms, 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) and a ratio of a number (c) of the at least one unit structure represented by Formula (3) satisfy 0.5.≦a≦0.95 and 0.05≦c≦0.3; and a compound having a protected carboxyl group represented by Formula (5): wherein: R 6 , R 7 and R 8 individually represent a hydrogen atom or a chained or cyclic alkyl group having 1 to 10 carbon atom, R 9 represents a chained or cyclic alkyl group having 1 to 10 carbon atom or an aromatic group having 6 to 20 carbon atoms, and R 7 and R 8 may be bonded to each other to form a ring.