A composition for forming a coating type BPSG film, containing one or more silicic acid skeletal structures represented by formula (1), one or more phosphoric acid skeletal structures represented by formula (2), one or more boric acid skeletal structures represented by formula (3), and one or more silicon skeletal structures represented by formula (4), wherein the composition contains a coupling between units in formula (4). The composition is capable of forming a BPSG film that has excellent adhesiveness in fine patterning, can be easily wet etched by a removing liquid which does not cause damage to a semiconductor substrate and a coating type organic film or a CVD film mainly consisting of carbon which is required in the patterning process, can maintain the peelability even after dry etching, and can suppress generation of particles by forming it in the coating process. ##STR00001##

A composition includes a polymer and a solvent. The polymer includes a group (X) which is at least one selected from the group consisting of: a group including at least two cyano groups; a group including B(OR).sub.2; a group including PO(OR).sub.2; and a group including P(OR).sub.2. Each R independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. The polymer preferably includes the group (X) at an end of a main chain thereof or at an end of a side chain thereof.

A composition includes a polymer and a solvent. The polymer includes a group (X) which is at least one selected from the group consisting of: a group including at least two cyano groups; a group including B(OR).sub.2; a group including PO(OR).sub.2; and a group including P(OR).sub.2. Each R independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. The polymer preferably includes the group (X) at an end of a main chain thereof or at an end of a side chain thereof.