Composition for resist underlayer film formation, resist underlayer film and forming method thereof, production method of patterned substrate, and compound

A composition for resist underlayer film formation comprising:

• a compound comprising a group represented by formula (1);
• and
• a solvent,
• wherein, in the formula (1),
• R1 represents an organic group having 2 to 10 carbon atoms and having a valency of (m+n), wherein the carbon atoms comprise two carbon atoms that are adjacent to each other, with a hydroxy group or an alkoxy group bonding to one of the two carbon atoms, and with a hydrogen atom bonding to another of the two carbon atoms, and wherein a hydrogen atom does not bond to the carbon atom to which the hydroxy group or the alkoxy group bonds;
• L1 represents an ethynediyl group or a substituted or unsubstituted ethenediyl group;
• R2 represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms;
• n is an integer of 1 to 3, wherein in a case where n is no less than 2, a plurality of L1s are identical or different, and a plurality of R2s are identical or different;
• * denotes a bonding site to a moiety other than the group represented by the formula (1) in the compound;
• and
• m is an integer of 1 to 3.