Abstract: To obtain both the highest possible maximum operating frequency f.sub.max and early voltage V.sub.A, a semiconductor device provided with a bipolar transistor including a collector region, a base region formed on the collector region, an emitter region formed in contact with the base region, a base leading electrode connected to the base region, and an emitter electrode connected to the emitter region, is characterized in that a ratio Q.sub.B /N.sub.c of base Gunmel number Q.sub.B to impurity concentration N.sub.C of the collector region of the bipolar transistor lies within a range from 0.2.times.10.sup.-3 cm to 2.5.times..sup.-3 cm.

Abstract: To enable a high speed operation and to increase the current gain, the disclosed a method of manufacturing a semiconductor device, comprising the steps of: forming a first semiconductor layer with a first-conductivity type in a semiconductor substrate; forming a second semiconductor layer with a second-conductivity type different from the first-conductivity type on the first semiconductor layer; insulation separating the formed second semiconductor layer into a first semiconductor region and a second semiconductor region by an insulating film; changing the second semiconductor region to the first-conductivity type; forming a pattern of an insulating film or a photoresist film having a hole at a partial area of the first semiconductor region of the semiconductor substrate; and implanting first-conductivity type impurities and second-conductivity type impurities at the first semiconductor region, respectively by use of the formed pattern as a mask, to form a first-conductivity type impurity region contacting wi

Abstract: A method of manufacturing a semiconductor device including selectively forming an element-isolating insulating layer on a surface of a semiconductor substrate to define active regions; forming a first insulating layer and removing respective portions thereof on surfaces of a second conductive type active region and a first active region of a first conductive type; oxidizing to form a gate oxide layer; forming and patterning a conductive layer to form a gate electrodes of MOS transistors and a base-extracting electrode of a bipolar transistor; forming an opening, in the base-extracting electrode, and a side wall insulating layer on an inner wall of the opening; removing first and second portions of the insulating layer to form an overhung portion; epitaxially growing a second conductive type semiconductor layer using the base-extracting electrode and active region of the first conductive type as a seed crystal; and selectively forming a first conductive type semiconductor layer that is to become an emitter tha