| 摘要 |
A well with a low impurity concentration is provided as a collector region on a semiconductor substrate. A trench is formed in a portion of the well from the surface toward the inside thereof. An insulating film, serving as a barrier against impurities, is formed on the side wall of the trench. Impurities are introduced through the trench and diffused to a high concentration into the well, thereby forming a high impurity concentration collector region which is connected to the collector electrode of the bipolar transistor. With the above-mentioned structure, the steps of diffusing antimony to a high concentration and growing an epitaxial silicon layer, which are indispensable to the prior art, are eliminated.
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