| abstract |
【Task】 An additive for a resist underlayer film forming composition and a resist underlayer film forming composition containing the additive are provided. [Solution] The additive for resist underlayer film forming compositions containing the copolymer which has a structural unit represented by following formula (1) thru | or Formula (4), and the resist underlayer film forming composition containing the said additive. [Chemical 1] (In the formula, each R 1 independently represents a hydrogen atom or a methyl group, Ar represents an arylene group, Pr represents a protective group or a hydrogen atom, and X represents a direct bond or —C (═O) O—R 2. - group, the -C (= O) O-R 2 - R 2 constituting the base represents an alkylene group having 1 to 3 carbon atoms, the alkylene groups are those that bind to a sulfur atom, R 3 represents a hydrogen atom, a methyl group, a methoxy group or a halogeno 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 represents a 4-membered ring to 7-7 This represents an organic group having a membered lactone skeleton, adamantane skeleton, or norbornane skeleton.) [Selection] Figure 1 |