| abstract |
[PROBLEMS] To provide a novel low resist film forming composition additive, and a resist low film film forming composition containing the additive. [Solution] An additive for a composition for forming a resist lower layer film, which comprises a copolymer having a structural unit represented by the following formulas (1) to (3). Wherein the additive comprises a resin different from the copolymer, an organic acid, a crosslinking agent and a solvent, and the content of the copolymer is 3 parts by mass to 40 parts by mass relative to 100 parts by mass of the resin. (Wherein R 1 is each independently a hydrogen atom or a methyl group, R 2 is an alkylene group having 1 to 3 carbon atoms, A is a protecting group, R 3 is a lactone skeleton of a 4-membered to 7-membered ring, R 4 represents an organic group having 1 to 12 carbon atoms, which may have at least one hydrogen atom substituted by a fluoro group and may have at least one hydroxy group as a substituent, and R < 4 > represents an organic group having a carbon skeleton, tricyclodecane skeleton or norbornane skeleton, A straight chain, branched or cyclic organic group. |