| 摘要 |
PURPOSE:To prevent occurrence of damage to an active region due to an anisotropic etching method, by making a silicon nitride film remain all the time on the active region, where an emitter region is to be formed in the future. CONSTITUTION:On a semiconductor region, a first insulating layer comprising an SiO2 film 14, an Si3N4 film 15, an SiO2 film 16 and an Si3N4 film 17 is formed. Etching is performing at a part other than a part, which is to become an active base region. Thus a substrate 10 is exposed. Then, an SiO2 film 18, an Si3N4 film 19, a polycrystalline silicon film 20 and an SiO2 film 21 are grown. The film 21 is made to remain only on the side wall of the first insulating film by an anisotropic method. With film as a mask, the film 20 is etched. Then the film 21 is released. The film 20 is oxidized, and an SiO2 film 22 is formed. With the film 22 as a mask, the film 19 is etched, and the film 22 is released. With the film 19 as a mask, selective oxidation is performed. After the film 18 is released, a polycrystalline silicon film 24 and photoresist 25 are provided. The entire surface is etched, and a region other than the first insulat ing layer is made to remain. Thus damage due to the anisotropic etching does not occur in the active base and the emitter region.
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