Composition for forming resist underlayer film and method for manufacturing semiconductor substrate

Abstract

This invention provides a composition for forming a resist underlayer film capable of forming a resist underlayer film with excellent resist pattern rectangularity, and a method for manufacturing a semiconductor substrate. A composition for forming a resist underlayer film comprises a polymer and a solvent, said polymer having a group containing at least one hydroxyl group selected from the group consisting of formulas (A1) to (A4). (In formulas (A1) to (A4), at least one of Re and Rf is a hydrogen atom. In formula (A4), at least one hydrogen atom is bonded to at least one carbon atom at the β position of the oxygen atom of OH.)