PURPOSE: To improve the step coverage of a metal electrode by plasma etching a nitride film with a resist as a mark and chemically etching an oxide film when forming a hole after laminating the oxide film and the nitride film on a semiconductor element, thereby forming a step in the hole.

CONSTITUTION: An oxide film 2 and a nitride film 3 are laminated to become a surface protective film on an Si substrate 1, a resist 4 of the prescribed shape is formed on the film 3 to be exposed with CF4+O2 plasma gas 5, and the exposed portion of the film 3 is first removed. After a tapered part is formed at the edge of the film 3 in this manner, the resist 4 is removed, and a resist 6 is again coated from the remaining part of the film 3 to the edge of the exposed film 2. Thereafter, the exposed part of the film 2 is removed by etching with fluoric acid solution, a tapered part is formed at the edge of the film 2 which similarly remains, and an aluminum electrode film 7 is coated from the remaining film having the step to the exposed surface of the substrate 1.