| 摘要 |
PURPOSE: To reduce base resistance and increase cut-off frequency, by defining the addition concentration of first impurities in a base layer, in the vicinity of a first junction region where the base layer is joined to an emitter region and in the vicinity of a second junction region where the base layer is joined to a collector layer from the vicinity of the first junction region. CONSTITUTION: The part constituted of an N<+> buried diffusion layer 13, an N<-> type epitaxial silicon layer 15, and an element isolation region 19 corresponds to a first conductivity type silicon base 21, a part of which is made a collector layer. On the silicon base 21, second impurities determine a second conductivity type, and the addition concentration of first impurities is lower than that of the second impurities and higher than or equal to 1×10<17> cm<-3> . A second conductivity type silicon layer 23 which contains the first impurities for determining the first conductivity type whose addition concentration is low in the upper part from the vicinity of a junction region to the silicon base 21 is formed. The silicon layer 23 is made a base layer.
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