HETEROJUNCTION BIPOLAR TRANSISTOR AND FABRICATING METHOD THEREOF

摘要

PURPOSE: A heterojunction bipolar transistor and its fabricating method are provided to minimize the stress transferred to a SiGe layer and prevent the leakage current by depositing an undoped polysilicon layer as a grain boundary on a SiGe base layer before forming an emitter layer. CONSTITUTION: A heterojunction bipolar transistor includes a semiconductor substrate(100), a SiGe base layer(130), and an emitter layer(160). The semiconductor substrate(100) includes impurities to perform a function of a collector. The SiGe base layer(130) is formed on the semiconductor substrate(100). The emitter layer(160) is formed by depositing a polysilicon layer on the SiGe base layer(130). A seed layer(140) is inserted between a grain the SiGe base layer(130) and the emitter layer(160) in order to determine a grain boundary of the emitter layer.