Abstract: A composition for forming a resist underlayer film, the composition including: a polymer containing a unit structure (A) represented by the following formula (1); and a solvent: wherein, in the formula (1), R1 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; and L1 represents a monovalent organic group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 40 carbon atoms, and a monovalent heterocyclic group, where at least one hydrogen atom which the alkyl group, the aryl group, and the monovalent heterocyclic group have is substituted with a halogen atom, and where at least one hydrogen atom which the alkyl group, the aryl group, and the monovalent heterocyclic group have may be substituted with a hydroxy group.

Abstract: A composition for forming a resist underlayer film that enables the formation of a resist pattern; and resist pattern production and semiconductor device manufacturing methods, which use the composition for forming a resist underlayer film. The composition for forming a resist underlayer film has a basic organic group substituted with a protecting group in the repeating unit structure of a polymer containing a heterocycle, or at a terminal thereof, and further includes a solvent. The polymer may include a heterocycle containing an alkenyl group having 2-10 carbon atoms. The polymer may have, in a main chain thereof, at least one structural unit represented by Formula (3). (In Formula (3), A1, A2, A3, A4, A5, and A6 each independently represent a hydrogen atom, a methyl group, or an ethyl group, and Q1 represents a divalent organic group including a heterocycle, and m1 and m2 each independently represent 0 or 1.