| 摘要 |
PURPOSE:To stabilize circuit operation by forming an island consisting of a semiconductor region having a conductivity type reverse to a base region into the base region so as to narrow the path of base currents for a bipolar transistor. CONSTITUTION:A low fr transistor is composed of an n<+> type buried layer 4, an n<-> type collector region 5, a p-type base region 6, an n<+> type emitter, region 7, an n<+> type leading-out region 8 and islands 9 made up of n<+> type semiconductor regions shaped into the base region 6 for increasing base resistance. Since base currents are difficult to flow by forming the n<+> type semiconductor regions 9 in the base region 6, the substantial value of the width of the emitter region 7 is reduced, thus elevating external resistance. That is, since the islands 9 composed of the semiconductor regions having a conductivity type reverse to the base region 6 are shaped into the base region 6 in the transistor, the transistor designed at high fr because base resistance is increased is brought to low fr, thus preventing the oscillation of a circuit.
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