| 摘要 |
PURPOSE:To enable to form a protective diode having an appropriate junction withstand voltage at an input protective device to check dielectric breakdown of the gate oxide film of an MOS transistor by a method wherein the whole of the surface of a diffusion layer is covered with a polycrystalline silicon layer. CONSTITUTION:An N type impurity region 43 to form the active region of a transistor is introduced according to diffusion or ion implantation, etc. on the surface of a P type silicon substrate 41, an SiO2 film is formed as an interlayer insulating film 44, and a contact hole is opened on the diffusion layer. A polycrystalline silicon layer 45 is formed on the surface in succession, and N type impurities are introduced according to diffusion or ion implantation, etc. from the surface to reduce resistance of the polycrystalline silicon layer. At this time, impurities are introduced also to the diffusion layer, and by selecting a suitable condition, junction depth as to form a protective diode having an appropriate withstand voltage for input protection can be realized. |
