Abstract: A method for high-fidelity fine patterning of a photoresist layer involving a dry-process development by exposure to a plasma gas. Following irradiation in a pattern with actinic rays, a photoresist layer coated on a substrate is heated in an atmosphere at 200.degree. to 500.degree. C. Subsequent exposure of the photoresist layer to a plasma gas gives a finely patterned resist layer with a very high residual film ratio or very small decrease in the film thickness.

Abstract: A method for high fidelity patterning of a photoresist layer involving a dry-process development by exposure to a plasma gas. A photoresist layer which had been irradiated in a pattern with actinic rays is heated at a temperature in the range from 200.degree. to 500.degree. C. by applying heat to the surface of the substrate opposite to the surface bearing the photoresist layer, for example, by placing the substrate on a hot plate with the uncoated surface in contact with the hot plate. Subsequent exposure to plasma gas gives a patterned resist layer with a very high residual film thickness.