A semiconductor apparatus is provided that is thermally stable in a post process and is suitable for fabricating a gate insulator having a laminated structure with various high permittivity oxides, and a process is provided for producing the same. In order to achieve a high function formation of a gate insulator, a silicon nitride film having a specific inductive capacity approximately twice as much as that of silicon oxide, and which is thermally stable, is not provided with a Si—H bond and is used as at least a portion of the gate insulator. Further, an effective thickness of a gate insulator forming a multilayered structure insulator laminated with a metal oxide having a high dielectric constant, in conversion to silicon oxide, can be thinned to less than 3 nm while restraining leakage current.