| 摘要 |
PURPOSE:To prevent permanent break down due to a parasitic transistor by a method wherein a protection element for a gate insulating film of an insulated gate FET is formed of the same semiconductor layer with a gate electrode monolithically on the inslating film. CONSTITUTION:P layers 3 and 30 provided on an N epitaxial layer 2 on an N<+> type Si substrate 1 are covered selectively with thin films 7 and 7a, subjected to the injection of ions by using, as masks, a gate electrode 9 and a poly-Si layer 8 serving as a protection element, and enlarged to be made into a P<+> layer 300 and a P<+> connection layer 7a which are shallow, and thereby the poly-Si layers 8 and 9 are made to be of P type. Next, an opening is made in an oxide film 7 by using a resist 11 and the poly-Si layers 8 and 9 as masks, and by the implantation of ions and enlargement, an N<+> layers 5 is made, while N<+> layers 8a, 8b and 9 are made simultaneously. Thereby the NPN type protection element is obtained, and an N<+> channel stop layer is also obtained in an N<-> layer 2. Lastly, covering is made by PSG 10, and a gate electrode G, a source electrode S and a protection ring electrode GR, formed of Al, are attched. Since the protection element is formed on an insulating film by this constitution, no SCR action occurs in this vertical type MOSFET and thus the reliability of the device is increased. |
