To provide an organic antireflection film composition which prevents reflection on a lower film layer, removes standing waves caused by light rays and variation in the thickness of a photoresist itself, and increases uniformity in the photoresist pattern in the process of forming a ultrafine pattern by using a lithographic photoresist and using 193 nm ArF light, in the manufacturing process of a semiconductor element, and also to provide a method for forming a pattern by using the composition.

The organic antireflection film composition comprises a crosslinking agent to allow the antireflection film to have a crosslinked structure, a polyvinyl phenol polymer having the structure of formula (1) used as an absorbent for light, a thermal acid generation agent, and an organic solvent. The composition further contains an acid diffusion prevention agent.