Vertical polysilicon-germanium heterojunction bipolar transistor

摘要

A vertical heterojunction bipolar transistor (HBT) includes doped polysilicon having a doping of a first conductivity type as a wide-gap-emitter with an energy bandgap of about 1.12 eV and doped single crystalline Ge having a doping of the second conductivity type as the base having the energy bandgap of about 0.66 eV. Doped single crystalline Ge having of doping of the first conductivity type is employed as the collector. Because the base and the collector include the same semiconductor material, i.e., Ge, having the same lattice constant, there is no lattice mismatch issue between the collector and the base. Further, because the emitter is polycrystalline and the base is single crystalline, there is no lattice mismatch issue between the base and the emitter.

主权项

1. A method of fabricating a heterojunction bipolar transistor (HBT) structure, comprising:
forming a collector and a base in a substrate, wherein said substrate comprises a buried insulator layer, wherein said collector comprises a first single crystalline germanium portion having a doping of a first conductivity type, and said base comprises a second single crystalline germanium portion epitaxially aligned to said collector and has a doping of a second conductivity type that is the opposite of said first conductivity type; forming deep trench isolation structures, wherein said deep trench isolation structures extend from a top surface of said substrate, through said collector to a depth beneath a top surface of said buried insulator layer; and forming an emitter comprising a polycrystalline silicon portion having a doping of said first conductivity type directly on said base.