PURPOSE: To increase a non-intensity difference between an exposed part and a nonexposed part even when a focusing value is varied to be exposed and to accurately form a pattern on a base to be processed with a step by forming an optical contrast increasing film having high transmittance against a strong light and low transmittance against a weak light on a resist film.

CONSTITUTION: A semiconductor substrate 11 having a step is coated with a photosensitive resin material exhibiting photosensitive characteristics for an i beam to form a resist film 12. Then, an aqueous soluble diazo series CEL film 13 is formed on the film 12. Thereafter, the film 12 is exposed in a desired pattern, irradiated with the i beam 15 through a mask 14. Then, the material is developed with developer. Thus, a focus margin can be increased by exposing the substrate provided with the CEL film on the resin material by using a projection exposure unit having a coherence factor σ value of 0.72 or more, and an accurate resist pattern can be formed on a base to be processed with a step.