Composition for forming resist lower layer film

1. A composition for forming a resist lower layer film, which contains (A) a resin, (B) a butyl ether group-containing crosslinking agent and (C) a solvent, wherein the resin (A) is a polymer having at least one structural unit selected from the group of the structural units represented by the following formulas (3) to (6):

R 3 is a hydrogen atom or a monovalent organic group; and R 4 and R 5 are each independently a monovalent atom or a monovalent organic group;

R 6 and R 7 are each independently a monovalent atom or a monovalent organic group;

R 8 is a hydrogen atom or a monovalent organic group, and R 9 is a monovalent atom or a monovalent organic group;

R 10 s are a hydroxyl group, an alkyl group which may have a substituent of 1 to 6 carbon atoms, an alkoxy group which may have a substituent of 1 to 6 carbon atoms, an alkoxycarbonyl group which may have a substituent of 2 to 10 carbon atoms, an aryl group which may have a substituent of 6 to 14 carbon atoms, or a glycidyl ether group which may have a substituent of 2 to 6 carbon atoms; n is an integer of 0 to 6; when n is 2 to 6, a plurality of R 10 s may be the same or different from each other; X is a methylene group, an alkylene group which may have a substituent of 2 to 20 carbon atoms, an arylene group which may have a substituent of 6 to 14 carbon atoms, or an alkylene ether group; m is an integer of 1 to 8; when m is 2 to 8, a plurality of Xs may be the same or different from each other; and n+m is an integer of 1 to 8, wherein the butyl ether group-containing crosslinking agent (B) is a nitrogen-containing cyclic compound having at least two butyl ether groups.

2. The composition for forming a resist lower layer film, according to claim 1 , wherein the nitrogen-containing cyclic compound is a compound having a glycoluril skeleton or a triazine skeleton.

3. The composition for forming a resist lower layer film, according to claim 1 , wherein the butyl ether group-containing crosslinking agent (B) is at least one kind of compound selected from the group of the compounds represented by the following formulas (1) and (2):

R 1 s are each independently a hydrogen atom, a methyl group, an ethyl group, a propyl group or a butyl group, with a proviso that at least two R 1 s are each a butyl group;

R 2 s are each independently a hydrogen atom, a methyl group, an ethyl group, a propyl group or a butyl group, with a proviso that at least two R 2 s are each a butyl group.