| 摘要 |
PURPOSE:To increase the speed of operation by preventing direct contact with an external base layer in high impurity concentration of an emitter layer, forming an internal base layer and the emitter layer in a self-alignment manner to the external base layer and inhibiting junction capacitance of an emitter and a base and base spreading resistance to small value. CONSTITUTION:An Si3N4 film 22' is removed, and boron ions are implanted to a substrate surface. Boron ions reach under a pad silicon oxide film 23'. The pad silicon film 23' in a transistor region is removed, and a polycrystalline silicon film 26, to which an emitter layer must be formed and an N type impurity is added, is shaped. The polycrystalline silicon film except the transistor region is removed selectively, and thermally treated. Consequently, the emitter layer 9 and an internal base layer 7 are formed. Since external base region layers spread in the lateral direction by the heat treatment, a P<+> layer 8 having intermediate impurity concentration of both the P type internal base layer 7 and the P<++> type external base layers 6 is formed automatically between both layers. A silicon oxide film 12 is shaped on the surface of a polycrystalline silicon layer 11 on the transistor region. |
