| 摘要 |
PURPOSE:To enable high speed operation by composing the sidewall of a base region of an oxide film and by reducing the junction capacitance of a collector base. CONSTITUTION:An oxidation resistance film 21 is formed on the Ntype epitaxial layer 12 on a silicon substrate 11 and after an SiO2 film (an oxide film) 22 is formed by using the film 21 as a mask, the pattern of a p<+> polysilicon film 21 is formed inside the mask 14 and an Si3N4 film 14 is etched by using the pattern as a mask. Further, after nondope polysilicon 29 is formed on all the surface, an impurity is diffused from the P<+> polysilicon 21 to the nondope polysilicon 29 by heat treatment, part of the nondope polysilicon 29 is changed to the P<+> polysilicon 23 and then, the P<+> polysilicon 21 and 23 are removed. In this case, the sidewall of the Si3N4 film 14 is also remove, then a P-type impurity is introduced on all the surface and oxidized by heat. After the Si3N4 film 14 is removed and the aperture in an emitter region is formed, an intrinsic base region 27 is formed by introducing the P-type impurity and then, an emitter electrode 21 is formed after an N-type impurity is introduced and the emitter region 28 is formed.
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