| 摘要 |
PURPOSE:To make the depth of a mesa groove small and to obtain a sufficiently broad depletion region, by connecting a layer, which is to become a base, to a layer, which is to become a collector, so that a round shape is formed. CONSTITUTION:On an n type silicon substrate, an SiO2 film 4 and a PSG film 5 are laminated. On these films, a photoresist film 6 is formed except for a part, which corresponds to a part where a p<+> layer that is to become a base is formed. Etching is performed in this state. Then, the SiO2 film 4, whose etched part forms a tapered surface, is formed. Then, the photoresist layer 6 and the PSG film 5 are removed. With the SiO2 film 4 as a mask, boron, which is p type impurities, is deposited and diffused. Then, a p<+> type layer, whose junction surface with the n type layer is rounded and expanded with respect to the n type layer, is formed. Thereafter, the SiO2 film 4 is removed. A comb shaped n<+> layer, which is to become an emitter, is formed by deposition and diffusion on the p<+> type layer. Then, a mesa groove 1 is formed at the peripheral part of the p<+> type layer. Thus the mesa type transistor is obtained. |
