| 摘要 |
PURPOSE:To obtain a conduction modulation type MOSFET capable of being used in the same manner as a normal power MOSFET and a bipolar Tr by setting a paprmeter value so as to satisfy predetermined relationship in order to make a current value on a latch-up larger than that on the saturation of a channel region. CONSTITUTION:An n<+> type layer 12 and a high-resistance n<-> type layer 13 are formed onto a p<+> type Si sbstrate, and a p<+> type guard ring layer 22 is shaped outside an effective element region while a p<+> type layer 16 is formed. Gate electrodes 19 are shaped through gate oxide films 18, and a diffusion layer 14 is formed while using the gate electrodes 19 as masks. A p<+> type layer 15 is shaped into the layer 14, As is implanted to form n<+> type source diffusion layers 17, and channel regions 21 are shaped. A source electrode 20 and a drain electrode 23 are formed. When the whole channel width per the unit area of the region 21 is represented by W, the area of the gate electrode 19 by Sa, the whole outer-circumferential length of the base diffusion layer 14 in the unit area by T, and the thickness of the gate insulating film 18 by (d), a para sitic thyristor is not latched up by satisfying a formula: (W.Sa)/(T.l.d)<1.1X10<8>.
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