An n-type TFT and a p-type TFT are realized by selectively changing only a cover coat without changing a TFT material using an equation for applying the magnitude of a difference in the Fermi energy between an interface of semiconductor and an electrode and between an interface of semiconductor and insulator. At this time, in order to configure a predetermined circuit, the process is performed, as a source electrode and a drain electrode of the p-type TFT and a source electrode and a drain electrode of the n-type TFT being connected all, respectively, and an unnecessary interconnection is cut by irradiating light using a scanning laser exposure apparatus or the like.