| 摘要 |
PURPOSE:To obtain a semiconductor device with small dimensions and a low base resistance without deteriorating its characteristics by a method wherein a high density base region and an emitter region are formed by self-alignment. CONSTITUTION:An N type Si substrate 11 is covered by a silicon oxide film 12 and the surface of the oxide film 12 is covered by a silicon nitride film 13. Then a polycrystalline silicon film 14 is selectively formed and using this silicon film 14 as a mask the silicon nitride film 13 is side-etched. Ionized boron is injected using the polycrystalline silicon film 14 as a mask and a high density base region 15 is formed onthe silicon substrate 11. Then after the polycrystalline silicon film 14 is removed, ionized boron is injected and a base region 16 is formed. Finally using the silicon nitride film 13 as a mask the surface of the silicon substrate 11 is covered with a silicon oxide film 17 and the silicon nitride film 13 and the silicon oxide film 12 are removed and phosphorus is added, so that an emitter region 19 is formed. |
