A polymer includes a structural unit represented by Chemical Formula 1 and an organic layer composition including the same. ##STR00001##
wherein in Chemical Formula 1, A is a carbon cyclic group including at least one hetero atom, B is one of groups in Group 1, where Ar.sup.1 to Ar.sup.4, R.sup.11 to R.sup.14, L and m are as defined in the specification and * is a linking point. When the carbon cyclic group includes at least two hetero atoms when the carbon cyclic group includes a pentagon cyclic moiety and the pentagon cyclic moiety includes a nitrogen atom (N) as a hetero atom, and the at least two hetero atoms are the same or different: ##STR00002##

A polymer includes a structural unit represented by Chemical Formula 1 and an organic layer composition including the same. ##STR00001##
wherein in Chemical Formula 1, A is a carbon cyclic group including at least one hetero atom, B is one of groups in Group 1, where Ar.sup.1 to Ar.sup.4, R.sup.11 to R.sup.14, L and m are as defined in the specification and * is a linking point. When the carbon cyclic group includes at least two hetero atoms when the carbon cyclic group includes a pentagon cyclic moiety and the pentagon cyclic moiety includes a nitrogen atom (N) as a hetero atom, and the at least two hetero atoms are the same or different: ##STR00002##

A photosensitive resin composition includes a polymer (A), a photoacid generator (B), and an organic solvent (C). The polymer (A) includes: a structural unit having a phenolic hydroxy group; and a (meth)acrylate-derived structural unit having an acid-dissociable group. The organic solvent (C) includes 3-ethoxyethyl propionate. A solid content concentration of the photosensitive resin composition is 30 mass % or more.

A photosensitive resin composition includes a polymer (A), a photoacid generator (B), and an organic solvent (C). The polymer (A) includes: a structural unit having a phenolic hydroxy group; and a (meth)acrylate-derived structural unit having an acid-dissociable group. The organic solvent (C) includes 3-ethoxyethyl propionate. A solid content concentration of the photosensitive resin composition is 30 mass % or more.

A composition for forming an organic film, containing: (A) a resin or compound for forming an organic film; (B) a polymer having a partial structure repeating unit represented by general formula (1); and (C) a solvent. The composition has excellent film-forming properties and embedding properties on a substrate, suppressing humps during an EBR step, and has excellent process tolerance when used as an organic underlayer film for a multi-layer resist, and provides a method for forming an organic film and pattern forming method using the composition:

##STR00001##

wherein R.sub.1 and R.sub.2 are hydrogen atoms or saturated or unsaturated organic groups having 1 to 20 carbon atoms, and have at least one fluorine-containing structure represented by the following general formula (2), at least one of R.sub.1 and R.sub.2 is an organic group that is not a hydrogen atom, and * represents an attachment point.

##STR00002##

A composition for forming an organic film, containing: (A) a resin or compound for forming an organic film; (B) a polymer having a partial structure repeating unit represented by general formula (1); and (C) a solvent. The composition has excellent film-forming properties and embedding properties on a substrate, suppressing humps during an EBR step, and has excellent process tolerance when used as an organic underlayer film for a multi-layer resist, and provides a method for forming an organic film and pattern forming method using the composition:

##STR00001##

wherein R.sub.1 and R.sub.2 are hydrogen atoms or saturated or unsaturated organic groups having 1 to 20 carbon atoms, and have at least one fluorine-containing structure represented by the following general formula (2), at least one of R.sub.1 and R.sub.2 is an organic group that is not a hydrogen atom, and * represents an attachment point.

##STR00002##