| 摘要 |
PURPOSE:To avoide the lowering of withstanding voltage by a protective diode by bringing the quantity of impurity per the unit area of an emitter for a parasitic bipolar transistor generated from the diode to that or less the unit area of a base while the quantity of the impurity per the unit area of a source is brought to that of more per the unit area of the emitter for the diode when an MOSFET and the diode for protecting a gate for the MOSFET are formed integrally. CONSTITUTION:A P channel forming region 4 is formed to an N type Si substrate, an N type source region 9 is shaped in the region 4, and a P type base region 5 for a protective diode is formed, and N<-> type emitter regions 17-1 and 17-2 are formed in the region 5. In this case, the quantity of impurity per the unit area of the region 9 is made higher than the regions 17-1 and 17-2 by one figure or three figures, and the quantity of the impurity pe the unit areas of the regions 17-1 and 17-2 is made lower than that of the region 5 by one figure in order to prevent the lowering of withstanding voltage by a parasisic bipolar transistor generated from the protective diode. |
