Lateral base design rules for optimized low-frequency noise of differentially grown SiGe heterojunction bipolar transistors

The low-frequency noise dependence on lateral design parameters was investi gated for SiGe heterojunction bipolar transistors fabricated by differentia l epitaxy. The low-frequency noise was found to vary substantially as a fun ction of the extrinsic base design. The dominant noise sources were located either at the interface between the polycrystalline and epitaxial Si/SiGe base, in the epitaxial Si/SiGe base link region, in the base-emitter deplet ion region, or at the thin SiO2 interface layer between the polysilicon and monosilicon emitter. Boron was found to passivate interfacial traps, actin g as low-frequency noise sources. Generation-recombination noise with a str ong dependence on the lateral electrical field was observed for some of the designs. (C) 2001 Elsevier Science Ltd. All rights reserved.