A method for forming a fine pattern on a chemical sensitization photoresist includes the consecutive steps of exposing a photoresist film with KrF excimer laser, developing the exposed photoresist film to form a photoresist pattern, separating protective group from the photoresist pattern, and heating the photoresist film to make the photoresist pattern to have a swelling property, thereby reshaping the openings in the photoresist pattern while reducing the size of the openings. The method achieves a finer pattern in a design rule of 0.30 to 0.18 &mgr;m without degradation of the shape.