| 摘要 |
A bipolar transistor excellent in the high speed performance comprises a buried region of a first conductivity type formed in a semiconductor substrate, said buried region having a high impurity concentration, a collector region of the first conductivity type formed on the buried region, a base region of a second conductivity type formed on the collector region, an emitter region of the first conductivity type formed on the base region, and an outer base region of the second conductivity type formed to surround the base and collector regions in such a manner that an ohmic contact is provided between the base region and said outer base region and a p-n junction is formed between the collector region and said outer base region. The concentration profile of the second conductivity type impurity in the depth direction of the outer base region is controlled in such a manner that, while the maximum voltage is applied between the base and emitter regions to turn the transistor on, the concentration of the second conductivity type impurity in the outer base region is kept higher than the concentration of the second conductivity type carrier in a base-widening region formed within the collector region, when the comparison is made at the same depth.
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