Patent ID: 8115256
Filing Date: 2012-02-14
Classification: H01L,H03K

Abstract:
1. A semiconductor device comprising: a second conductivity type first semiconductor layer having a main surface; a first conductivity type first well formed in said second conductivity type first semiconductor layer and a top surface of said first conductivity type first well is separated from said main surface by an element isolation oxide film; a second conductivity type second field-effect transistor formed on said main surface and in said first conductivity type first well; a first conductivity type first field-effect transistor formed on said main surface outside of said first conductivity type first well; wherein said first conductivity type first field-effect transistor and said second conductivity type second field-effect transistor including sources, drains and gates electrodes respectively, said drains being connected to each other and said gate electrodes being connected to each other to form an inverter; a bipolar transistor formed on the main surface outside of said first conductivity type first well, wherein said bipolar transistor including a collector, a base and an emitter, said base receiving an output of said inverter; a first conductivity type first impurity region constituting said drain of said first conductive type first field-effect transistor and a first conductivity type second impurity region constituting said base of said bipolar transistor have different impurity concentrations from each other, said first conductivity type first impurity region and said first conductivity type second impurity region are so formed as to be in direct contact with each other, and the thickness of said first conductivity type first impurity region is smaller than the thickness of said first conductivity type second impurity region, wherein said first conductivity type first impurity region is so formed as to overlap with said first conductivity type second impurity region at a position closer to said base of said bipolar transistor than a central portion of said first conductivity type second impurity region, a second conductivity type third impurity region constituting said emitter of said bipolar transistor is separated from a first conductivity type fourth impurity region constituting said source of said first conductivity type first field-effect transistor by said first conductivity type first impurity region.