PURPOSE: To obtain the electrode for the practical semiconductor device using poly Si by positioning an oxide film with approximately 1.5∼3μm thickness between a poly Si layer and a metallic conductor wiring layer.

CONSTITUTION: When a transition metallic film 15 made of Mo, etc. is evaporated onto the poly Si 13 under vacuum and treated at approximately 1,000°C in N2, O2 diffuses in Mo, and the SiO2 films 14, 141 are formed to the interface and the surface. The film 141 is normally removed. A Mo film 15 is stacked onto the film 14, a stratiform gate region is shaped by films 12∼15, a source 161 and a drain 162 are formed to a Si substrate 11 while using the region as a mask, the surface is coated with SiO2 17, Al electrodes 181∼183 are attached and a FET is completed. In this constitution, since the SiO2 14 obstructs the direct reaction of the Mo 15 and the poly Si 13 even when the course Mo film formed through sputtering, etc. is treated at a high temperature and compacted, Mo holds original high conductivity, and the FET, the electrical characteristics of a gate electrode thereof are excellent and which is proper to switching at high speed, is obtained.