A surface of a semiconductor substrate of silicon is supplied with 4-trimethylsiloxy-3-penten-2-one serving as a surface treatment agent. Thus, H in OH groups existing on the surface of the semiconductor substrate is substituted with Si(CH.sub.3).sub.3 (i.e., a trimethylsilyl group), resulting in producing CH.sub.3 COCH.sub.2 COCH.sub.3 (i.e., acetylacetone). Then, the surface of the semiconductor substrate is coated with a resist, exposed by using a desired mask, and subjected successively to PEB and development, thereby forming a resist pattern thereon. Since the surface of the semiconductor substrate is treated with 4-trimethylsiloxy-3-penten-2-one, the surface of the semiconductor substrate is made to be hydrophobic, so that the adhesion of the semiconductor substrate can be improved. As a result, the resultant resist pattern has a satisfactory shape free from peeling.