| 摘要 |
PURPOSE:To protect the MOSFET by providing a layer of 10<13>-10<15>cm<-2> between a pair of impurity layers of 10<15>cm<-2> or more so as to contact with one of them, in a poly Si layer on an insulating film on an Si substrate, and forming a P-N junction. CONSTITUTION:A P layer 10 and an N type source and drain 11 are selectively formed in an N layer 1 of an N type Si substrate 1 and coated by a gate oxide film 2 and a field oxide film 3. A gate electrode 9 is provided on the gate oxide film 2. A pair of N<+> poly Si layers 5 and 6 having specified concentration are formed on the field oxide film 3 so as to hold a P<+> poly Si layer 4. The surface is coated by an oxide film 15. A hole is perforated. An electrode 7 is provided on the N<+> layer 15, and connected to a source electrode 12. An electrode 8 is attached to the N<+> layer 6. Thus a protecting diode 16 is connected to a longitudinal type FET Q1 so as to prevent the application of excessive surge on the gate terminal 9 of the FET. In this constitution, the protecting diode has the characteristics which does not narrow the operating range of the FET, constitutes the breakdown strength equal to that of the diode itself, and has the large effect. |
