| abstract |
There is provided a resist underlayer film forming composition capable of forming a flat film, exhibiting high etching resistance, good dry etching rate ratio and optical constant, good coverage even for so-called stepped substrates, and small difference in film thickness after embedding. Further, a method for producing a polymer suitable for the resist underlayer film-forming composition, a resist underlayer film using the resist underlayer film-forming composition, and a method for producing a semiconductor device are provided. A reaction product of an aromatic compound (A) having 6 to 60 carbon atoms and a carbonyl group of the cyclic carbonyl compound (B) having 3 to 60 carbon atoms, and a solvent, wherein the reaction product is the cyclic carbonyl compound One carbon atom of (B) is a resist underlayer film-forming composition in which two aromatic compounds (A) are connected. |