MANUFACTURE OF SEMICONDUCTOR DEVICE

PURPOSE:To improve the insulating performance of an insulating film and to prevent the shortcircuit between the emitter and the collector by forming the insulating film on emitter and base regions with a dioxidized silicon layer by the thermal oxidation of a single crystalline silicon and self-aligning and forming the base and emitter regions. CONSTITUTION:An N type buried layer 22 is selectively formed on the surface of a P type silicon substrate 21, and an N type epitaxial layer 23 is further arranged. A photoresist layer is arranged to cover regions to be formed with emitter and base contact on a polycrystalline silicon layer 28. Base regions 35a, 35b of 3,000Angstrom in depth and 10 pieces/cm of surface impurity density are formed on the layer 23. With the aluminum layer as a mask a polycrystalline silicon layer 34 is selectively etched, and base, emitter and collector electrodes are formed.