| 摘要 |
PURPOSE:To clearly specify the end of etching in each stage and keep the characteristic without etching of the silicon substrate working as the base material. CONSTITUTION:The P-N junction surface of base 2 and emitter 3 is left in such a way as being covered with a silicon oxide film 4, and a polycrystal silicon film or that including oxygen 5 is formed on the entire part by the vapor growth method. The base electrode part of polycrstalline silicon film 5, P-N junction part of base and emitter and the emitter region are etched. For the etching, the KOH aqueous solution or CF4-O2 plasma is used, but since a selection ratio for the etching of silicon oxide film and polycrystalline silicon is large, the silicon oxide film 4 protects the silicon substrate during the etching of the polycrystalline silicon film 5. |
