SEMICONDUCTOR DEVICE WITH MONOCRYSTALLINE EXTRINSIC BASE REGION AND METHOD OF FABRICATION THEREFOR

A semiconductor device, such as a heterojunction bipolar transistor (HBT), may include an extrinsic base region (114) that is connected to a collector region (104) via semiconductor material formed in an opening (111) in one or more dielectric layers (110, 120) interposed between the extrinsic base region and the collector region. The extrinsic base region is formed from monocrystalline semiconductor material, such as silicon or silicon germanium, via selective epitaxial growth. An intrinsic base region (122) may be formed adjacent to the extrinsic base region and may be interposed directly between the collector region (104) and an intrinsic emitter region (124). An isolation region (105) is present in the collector, splitting the collector in a region connected to the extrinsic base and a region connected to the intrinsic base. An HBT with such an arrangement may have reduced base-collector capacitance and reduced base resistance compared to some conventional HBTs.