Non-selective growth of SiGe heterojunction bipolar transistor layers at 700C with dual control of n and p type dopant profiles

Abstract

This paper describes the growth of the collector, base, and emitter layers of a SiGe HBT in a single epitaxy process. A non-selective SiGe heterojunction bipolar transistor growth process at 700 °C has been developed, which combines n-type doping for the Si collector, p-type doping for the SiGe base and n-type doping for the Si emitter cap. Control of the collector doping concentration by varying the growth conditions is shown. The boron tailing edge from the SiGe base into the Si emitter layer was removed by interrupting the growth process with a hydrogen flow after the SiGe base growth but before the Si emitter growth to remove the dopant gas from the chamber. The layer thicknesses are compared using three different analytical techniques–secondary ion mass spectroscopy (SIMS), transmission electron microscopy (TEM), and spectroellipsometry. A good agreement was obtained for the three different methods.