| 摘要 |
PURPOSE:To improve the withstand of the junction of an emitter region and a base region by forming the portion adjacent to the bonding end of the emitter and base regions terminated on the surface of a semiconductor layer of the base region in a low impurity density. CONSTITUTION:An n<+> type buried layer 2 is formed in a p type Si substrate 1, and n type epitaxial layer 3 is formed on the substrate 1. Then, a p type base region 5 and a p<+> type graft base region 6 are formed in the layer 3. Then, an n type impurity such as As is implanted to the surface of the layer 3 through a thin SiO2 film 11 formed on the surface of the layer 3, and heat treated. Then, after the film 11 is removed, an SiO2 film 7 and As-doped polycrystalline Si film 8 are formed in the layer 3, heat treated to form an n<+> type emitter region 9. In an npn type bipolar transistor formed in this manner, the impurity density of the portion adjacent to the surface of the layer 3 of the region 5 decreases. Thus, the reverse withstand in the bonding end 14a of the emitter and base junction 14 can be enhanced. |
