| 摘要 |
PURPOSE:To establish MOSFET of high dielectric strength, by providing the low concentration layer from the substrate in the semiconductor substrate under the opening of insulation film. CONSTITUTION:The SiO2 film 13 of the P<+> substrate 10 is opened and the P layer 17 is formed with N type ion injection. The concentration and depth of the layer 17 can be determined by referencing the depth of the next N<+> diffusion. Further, the P<-> epitaxial layer 12, gate oxide film 13, and polycrystal Si gate electrode 14 are formed selectively. Succeedingly, the electrode 14 is made conductive with the N<+> diffusion to form the N<+> layers 15 and 16. In this case, even if the N<+> layers 15 and 16 are extended to the P<+> substrate side, the junction is formed with the N<+> layer and the P layer 17. Since the layer 17 is selected with the concentration to obtain desired greater dielectric strength, the increase in the junction capacitance and the lowering in the source and drain dielectric strength as conventional devices can not be taken place. |
