| 摘要 |
PURPOSE:To prevent the variation of the threshold voltage of a transistor by forming Si3N4 onto the surface of SiO2 and stacking first poly Si, its oxide film and second poly Si in succession. CONSTITUTION:The field oxide film 2 and gate oxide film 41 of a Si substrate 1 are treated in NH3 at a high temperature and coated with a Si3N4 film 42, and a poly Si oxide film 6 is formed onto the surface of poly Si 5 formed selectively. Doped poly Si 8 is laminated selectively, an impurity diffusion layer 9 is formed, and the semiconductor device is completed in the same manner as conventional devices. Since the gate oxide film 41 is coated with the nitride film in this constitution, doping from the film 5 is not generated into an element forming region when forming the poly Si oxide film 6, threshold voltage is not varied, and stable characteristics are obtained. An impurity is added sufficiently to poly Si 5 and resistance can be reduced because doping is not generated, the thickness of the film 6 is not limited even when the gate oxide film is thin, and dielectric resistance between the films 5, 8 does not lower and parasitic capacitance does not increase. |
