Patent ID: 7268376
Filing Date: 2007-09-11
Classification: H01L

Abstract:
1. A bipolar transistor comprising: a semiconductor substrate of a first conductivity type; a collector region of a second conductivity type, which is defined by first and second isolation regions on the semiconductor substrate; a first base semiconductor layer of the first conductivity type formed of a silicon germanium (SiGe) layer, which extends across the upper surface of the collector region to the upper surface of the first and second isolation regions; emitter insulating layers formed on the first base semiconductor layer, wherein the emitter insulating layers define an emitter junction portion on the first base semiconductor layer; an emitter region of the second conductivity type formed on the emitter junction portion on the first base semiconductor layer to contact the first base semiconductor layer through the emitter junction portion, wherein the emitter region has sidewalls being in contact with sidewalls of the emitter insulation layers; second base semiconductor layer patterns of the first conductivity type formed of a silicon layer, which is formed directly on portions of the first base semiconductor layer except for portions of the first base semiconductor layer having the emitter region and the emitter insulating layers, wherein the second base semiconductor layer patterns are spaced apart from the emitter region by the emitter insulating layers positioned between the emitter region and the second base semiconductor layer patterns; base ohmic layer patterns formed on the second base semiconductor layer patterns; an emitter electrode formed on the emitter region; base electrodes formed on the second base semiconductor layer patterns at both sides of the emitter electrode; first and second insulating layer patterns formed between the first and second isolation regions, respectively, and the first base semiconductor layer, under the base electrodes; and first and second silicon layer patterns formed between the first and second insulating layer patterns, respectively, and the first base semiconductor layer.