Polymer and composition for forming organic film, substrate for manufacturing semiconductor apparatus, method for forming organic film, and patterning process

A composition for forming an organic film, comprising:

• (A) a polymer having a repeating unit shown by the following general formula (1);
• and
• (B) an organic solvent,
• wherein AR1, AR2, and AR3 each represent a benzene ring, a naphthalene ring, or an anthracene ring which optionally have a substituent;
• carbon atoms on aromatic rings of AR1 and AR2, or AR2 and AR3, optionally bond to each other directly or via a linking group to form a bridge structure;
• R1 and R2 each independently represent a hydrogen atom or an organic group having 1 to 30 carbon atoms;
• when R1 and R2 are the organic groups, R1 and R2 optionally bond to each other within a molecule to form a cyclic organic group;
• and Y represents a group shown by the following formula (2),
• —R3—C≡C—R4 (2)
• wherein R3 represents a single bond or a divalent organic group having 1 to 20 carbon atoms;
• R4 represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms;
• and a dotted line represents a bonding arm.