Composition and method for manufacturing semiconductor substrate

A method for producing a semiconductor substrate, comprising:

• applying a composition for forming a resist underlayer film directly or indirectly to a substrate to form a resist under layer film;
• applying a composition for forming a resist film to the resist underlayer film to form a resist film;
• exposing the resist film to radiation;
• and
• developing the exposed resist film,
• wherein the composition for forming a resist underlayer film comprises:
• a polymer comprising a repeating unit represented by formula (1);
• and
• a solvent,
• wherein, in the formula (1),
• R1 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms,
• L1 is a single bond or a divalent linking group, and
• Ar1 is a monovalent group comprising an aromatic ring having 6 to 20 ring members, a hydrogen atom of the aromatic ring is substituted with at least one halogen atom, and the monovalent group represented by Ar1 further comprises at least one group selected from the group consisting of a group represented by formula (2-1), a group represented by formula (2-2), a group represented by formula (2-3), a group represented by formula (2-4), a group represented by formula (2-5), a group represented by formula (2-6), a group represented by formula (2-7), and a group represented by formula (2-8),
• wherein, in the formulas (2-1) to (2-8) * is a bond to an atom constituting Ar1, and R7 is a divalent organic group having 1 to 20 carbon atoms or a single bond,
• in the formulas (2-1) and (2-7), R8, R9, and R10 are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms,
• in the formula (2-2), ** is a bond to an atom constituting Cy, Cy is a ring structure having 3 to 20 ring members formed together with two carbon atoms in the formula, R11 is a hydrogen atom, a monovalent organic group having 1 to carbon atoms, or a bond to **, and R12 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and
• in the formula (2-3), R13 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms.