| abstract |
[Task] An additive for a resist underlayer film forming composition, and a resist underlayer film forming composition comprising the additive are provided. [Solutions] An additive for a resist underlayer film forming composition comprising a copolymer having structural units represented by the following formulas (1) to (4), and a resist underlayer film forming composition comprising the additive. [Formula 1] (Wherein, R 1 each independently represents a hydrogen atom or a methyl group, Ar represents an arylene group, Pr represents a protecting group or a hydrogen atom, X represents a direct bond or a -C (= O) OR 2 -group, R 2 constituting this -C (= O) OR 2 -group represents an alkylene group having 1 to 3 carbon atoms, and this alkylene group is bonded to a sulfur atom, and R 3 is a hydrogen atom, a methyl group, a methoxy group or a halogen Represents a no group, R 4 represents an alkyl group having 1 to 3 carbon atoms in which at least one hydrogen atom is substituted with a fluoro group, and Z is an organic having a 4- to 7-membered ring lactone skeleton, an adamantane skeleton, or a norbornane skeleton. Group.) |