| 摘要 |
PURPOSE:To obtain a high hFE transistor which has high reliability without affection of the influences of cationic ions and boundary level on the surface of a base region by decreasing the impurity density of the entire base region and forming a high impurity substance region only on the surface of the base region. CONSTITUTION:In the fist step, a base region 12 and an emitter region 13 are formed by double diffusion on the surface of a silicon substrate 11. In this step, the region 12 is formed in P type with selective diffusion of boron, the impurity density is set to 4X10<17>cm<-3> or lower, thereby obtaining high hFE. Then, in the second step, oxidized films 14 on the surfaces of the base and emitter regions 12, 13 are removed, and P type impurity is ion implanted or deposited to form a high impurity region 15 on the surface. In this step, the surface impurity density of the region 12 is set to 1X10<18>cm<-3> or higher, thereby suppressing the parasitic effect. Then, in the third step, oxidized films 16 are formed by a CVD method on the surfaces of the regions 12, 13. In this step, the films 16 are formed by a CVD method on the silicon surface at a low temperature in a thickness of approx. 5,000Angstrom , the impurity is introduced into the film 16 from the region 15, thereby reducing the surface impurity density of the region 12. |
