| 摘要 |
PURPOSE:To prevent the lowering of withstanding voltage between an emitter and a collector due to the diffusion and redistribution of an impurity from a buried region by eliminating the need for heat treatment at a high temperature. CONSTITUTION:A P-type silicon substrate 21 and an N<+> type buried region 22 are formed, and a CVD oxide film 23 is deposited. A boron-doped polycrystalline silicon film is deposited, and a polycrystalline silicon film pattern 24 is shaped through patterning. A CVD oxide film 25 is deposited on the whole surface, and the surfaces of the polycrystalline silicon film pattern 24 and the CVD oxide film 25 are flattened. A thin CVD oxide film 26 is deposited on the whole surface to coat the upper section of the polycrystalline silicon film pattern 24, and one part of the CVD oxide film is etched until it reaches the buried region 22 to form an opening section 27 for a collector extracting region. Phosphorus is added, a photo-resist is applied, and the whole surface is etched back, thus burying one part of a polycrystalline silicon film 28 into the opening section 27, then shaping an N<+> type collector extracting region 29. Accordingly, only a heat treatment process under moderate conditions which follow is left. |
