SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF

PROBLEM TO BE SOLVED: To provide a bipolar transistor, which is low in a base resistance and can be actuated at a high speed, and the manufacturing method of the bipolar transistor. SOLUTION: A collector layer 12 is formed on a region on the vicinity of the surface of an Si substrate 10 and an Si1-xGex/Si layer 21 is formed on the layer 12. A polysilicon emitter layer 30 is provided on the central part of the layer 21 and a third insulating layer 42, a first sidewall 24, a P+ regrowth Si layer 25 and a fourth insulating layer 26 are provided in such a way as to encircle the layer 30. An internal base 29 and an external base 19 are formed in a self alignment and the distance (W2-W1)/2 between an emitter-base junction part and the base 19 is set so as to coincide with the thickness of the sidewall 24. As there is no need to anticipate a margin, a base resistance can be reduced and at the same time, the parasitic capacitance between electrodes can be also reduced.