| 摘要 |
PURPOSE:To diffuse impurities at a desired concentration in a base region only by heat treatment by depositing a polycrystalline silicon film after dividing its deposition into a plurality of times until it comes to 2000 Angstrom that is enough to form an emitter region; besides, by adding impurity atoms into respective polycrystalline silicon films each time its silicon film is deposited. CONSTITUTION:The second conductivity type buried layer 2 as well as an epitaxial layer 3 which are different from a silicon semiconductor substrate 1 are formed one after another on the first conductivity type silicon semiconductor substrate 1. A base region 6 having the same conductivity type as the first one is formed in a collector region that is formed by the epitaxial layer 3 and an opening part is prepared at an insulating protecting film 5 on the base region 6. The whole film thickness composed of polycrystalline silicon films 7a-7c is set to come to 2000 Angstrom or more by repeating alternately in order a plurality of times of deposition of the polycrystalline silicon film 7a as well as addition of impurities of the same conductivity type as the second one to the whole surface of the substrate including the opening part. Subsequently, the films are treated by heat with a lamp annealing technique and an emitter region 8 is formed by diffusing the impurities contained by respective films of the polycrystal silicon films into the base region 6 through the opening part.
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