| 摘要 |
PURPOSE:To obtain a semiconductor device capable of securing high cut-off frequency in low current region by completely removing the region to become an external base region, thereby extermely reducing the base resistance. CONSTITUTION:After an N type epitaxial layer 2 is formed on one conductive type, e.g., N type collector substrate 1, an inner base region 3 and an external base region 4 as well as a graft base region 4' are formed by reverse conductive type, e.g., P type impurity diffusion in the layer 2. Thereafter, a polycrystalline silicon layer is formed on an N type semiconductor substrate formed with the P type base region, and the layer 2 which includes the previous base regions 4, 4' is cut to the prescribed depth in case of machining the electrode 6'. Thereafter, an N type emitter region 8 is formed on the P type base region with the N type polycrystalline silicon electrode 6' as a diffusion source. Further, a metal electrode 6 and a base electrode 7 at the root of the projected internal base 3 are formed on the electrode 6'. |
