| 摘要 |
<p>PURPOSE: To obtain a bipolar transistor of an SICOS structure, which can reduce the area of an emitter by a method wherein an external base region on the projected sidewall parts of an epitaxial layer and after a sidewall is formed on a projected top surface, a diffusion is performed for forming an emitter region. CONSTITUTION: A N-type epitaxial layer 3 is grown on a semiconductor substrate, a thermal diffusion is performed and an oxide film 16 and a nitride film 17 are formed in order. Then, the films 17 and 16 are etched away excluding emitter and base regions, the layer 3 is subjected to anisotropic etching using both of these films 16 and 17 as masks, and projected side walls are formed. Then, the surface of a polysilicon film 22 is oxidized; impurities being contained in this film 22 are made to diffuse in the layer 3 of the projected sidewalls; and an external base region 12 is formed. The exposed film 17 is etched; the film 16 is made to expose; an oxide film 25 is formed on the whole surface; and a sidewall 25 is formed on the projected top surface 22 and the end surfaces of an oxide film 24 by anisotropic etching.</p> |
