| 摘要 |
PURPOSE:To enable obtaining the performance of a high speed transistor by forming a hetero junction with a P-type semiconductor layer which has a wider band gap than that of a base region on a PN junction plane in an emitter region and a collector region. CONSTITUTION:After an n-type base region 6 is formed on an Si substrate 1, an insulation film (SiO2 film) 9 and a p-type polysilicon layer 10 are laminated on the base region. After a base width region is selectively opened in the insula tion layer and the polysilicon layer, an overhang 12 is formed like eaves on the polysilicon layer by overetching the insulation film and a p-type polysilicon layer 13 which has a greater band gap than Si is laminated on all the surface. After the p-type semiconductor layer other than the p-type semiconductor layer laminated under the overhang is removed, the insulation film (SiO2 film) 9 is coated and an emitter region 4 and a collector region 5 are formed. This enables obtaining the performance of a high speed transistor.
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