| 摘要 |
PURPOSE:To avoid an element breakdown due to a parasitic transistor even if the number of elements is reduced by forming a bipolar transistor formed in the same substrate as that of a power MOSFET as a lateral transistor in which a second base region having a reduce concentration by a collector region in a short base width is employed as a substantial base and in a 2-layer base structure made of a high concentration first base region and a second base region having a low concentration and a high depth. CONSTITUTION:A second base region 21 formed in the same process as that of p<+> type body regions 5 of high concentration M1 and M2 and an emitter region 22 formed in the same process as that of an n<+> type source region 4 are provided in a first base region 20 formed in the same process as that of the p-type body region 3 of a vertical power MOSFET (main MOSFET.M1 and current mirror MOSFET.M2). A parasitic bipolar transistor T4 designated by a broken line is formed in a vertical direction, but since the base width of the T4 is considerably layer than that of a bipolar transistor T1 and the concentration of the region 21 is high, it can be so formed as to ignore its hFE. Accordingly, it can prevent a malfunction due to a parasitic bipolar effect. |
