To the surface of a semiconductor substrate made of silicon, isopropenoxytrimethylsilane is supplied as a surface treating agent to render the surface of the semiconductor substrate hydrophobic and increase adhesion to the semiconductor substrate. Thus, Si(CH 3 ) 3 (trimethylsilyl group) is substituted for the hydrogen atom of an OH group on the surface of the semiconductor substrate, resulting in (CH 3 ) 2 CO (acetone). Subsequently, a chemically amplified resist is applied to the surface of the semiconductor substrate and exposed to light by using a desired mask, followed sequentially by PEB and development for forming a pattern. Since the surface treating agent does not generate ammonia, there can be formed a pattern in excellent configuration with no insoluble skin layer formed thereon.