| 摘要 |
PROBLEM TO BE SOLVED: To improve electrostatic break-down voltage between the base and collector terminals, without deteriorating the high speed property of a bipolar transistor. SOLUTION: A semiconductor substrate comprises a recess provided on the surface of a collector region, an intrinsic base region 7 formed from the inner surface of the recess and an emitter region 11 formed in the base region, the recess and the interface between the intrinsic base region and the collector region form gentle curved surfaces having no abrupt edges, so that a current between the base and the collector terminals with applied electrostatic charges does not concentrate on the intrinsic base region 7 closest to an outer base region 12, and the recess forming is made through isotropic plasma etching.
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