| 摘要 |
PROBLEM TO BE SOLVED: To reduce manufacturing costs, reduce yield, and improve electrical characteristics by reducing the number of machining processes in comparison with those of prior art, and reducing machining variations. SOLUTION: A third silicon oxide film is made to remain only at the center on an intrinsic base layer. A resist film is formed, and a P-type polycrystalline silicon film, a P-type silicon film, and a first polycrystalline silicon film are etched at the same time, thus reducing the number of etching. In addition, since the P-type silicon film and the first polycrystalline silicon also function as a portion of an external base electrode, the base resistance of a bipolar transistor is reduced.
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