| 摘要 |
PURPOSE:To form transistors having different hFE values on a chip simultaneously, by providing with a second base region being deeper than a first base region and overlapping the emitter region. CONSTITUTION:A second base region 23 being deeper than a first base region 18 and overlapping the emitter region 20 is formed. In such a structure, since the base width of the second base region 23 is wider, recombination current due to extinction of injected carriers at the base of the transistor is increased to reduce the hFE value, which is determined by the impurity concentration and diffusion depth of the second base region 23 and the overlapping area between the second base region 23 and emitter region 20. If these regions are formed on respective islands 16 simultaneously, the hFE values can be controlled by the overlapping area between the second base region 23 and emitter region 20, because the impurity concentration and diffusion depths are all uniform. As the overlapping area increases, the recombination current on account of the second base region 23 increases considerably to reduce the hFE. |
