PURPOSE: To form a fine resist pattern with good accuracy in a rectangular shape on an irregular substrate, by making an inorg. substance a mask by using O2 plasma and by etching a resist.

CONSTITUTION: Oxidized films 2 are formed on a Si wafer 1 by a wet type exidation, and an etching of the films 2 is performed by patterning the films 2 and by using a reactive ion etching, and the difference in level is formed on the Si wafer 1 to form a substrate 3. Then, a positive photoresist 4 is spin-coated on the substrate 3 and its surface is made plane. Films 5 of an inorg. substance are accumulated on the resist 4 by using a high frequency spattering device and an AgCl layer 6 is accumulated on films 5. Further, films 5 are exposed and a dry development of the films 5 is performed by using a parallel plane plate type plasma etching device. O2 is supplied and the etching of the resist 4 is performed by making exposed parts 5a of the films 5 a mask.