Photosensitive resin composition for far-ultraviolet exposure

A pattern forming method, which comprises:

• forming a thin film of a photosensitive resin composition on a substrate, light-exposing the thin film with an ArF excimer laser, and developing the exposed thin film,
• said photosensitive resin composition comprising a non-aromatic series resin having a substituent capable of increasing the solubility of the resin in an alkali developer by an acid and an N-hydroxymaleinimide sulfonate photo acid generator represented by formula (I):
• ##STR17## wherein R.sub.1 and R.sub.2, which may be the same or different, each represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, or a cycloalkyl group having not more than 6 carbon atoms;
• R.sub.1 and R.sub.2 may combine via an alkylene chain to form a ring;
• and R.sub.3 represents an alkyl group, a perfluoroalkyl group, a cyclic alkyl group, or a camphor group,
• wherein the resin has an alicyclic alkyl group in the side chains.