| 摘要 |
PURPOSE:To obtain an FET having a high electrostatic breakdown voltage by thickening a poly-crystalline Si resistance more than a poly-crystalline Si layer composing of an internal circuit when the poly-crystalline Si resistance is used as a protection circuit for an IGFET input gate or a part of this circuit. CONSTITUTION:An n<+> type diffusion layer 9 for an input gate protective circuit, a drain layer and a source layer 13 are formed on a p type Si substrate 12. A field insulaing film 11 is formed on the whole surface to open windows. A poly-crystalline Si resistance 5 for input gate protective circuit and wiring metals 8, 8' are formed on the layer 9 and the layers 13 respectively while extending the resistance 5 and the metals 8 and 8' on the film 11. Next, an input electrode 7 is similarly installed on one end of the resistance 5 by positioning the electrode 7 on the film 11 and a poly-crystalline Si layer 6 for internal circuit composition is provided on the exposed surface of the substrate 12 between two regions 13 through a thin insulating film and the whole surface is covered with an insulating film 10 for protection. In this composition, the poly-crystalline layer 5 is made thicker than the poly-crystalline Si film 6 to increase dielectric strength without causing any influence on the internal circuit. |
