As- or P-Doped Si Layers Grown by RPCVD for Emitter Application in SiGeC HBTs

Abstract

A new module for the emitter formation in a bipolar transistor is presented. Arsenic- or phosphorus-doped polycrystalline silicon layer for the emitter formation is deposited in a reduced pressure chemical vapor deposition reactor using silane as the silicon source gas. Characteristics such as the carrier concentration, conductivity, surface morphology, and thermal stability of the polycrystalline-silicon layer as well as the influence this layer has on a SiGeC transistor structure during the drive-in step area studied. The active carrier concentration of the as-grown sample is strongly dependent on the deposition temperature, especially arsenic doped layers which exhibit more than one order of magnitude difference. However, the carrier concentration for the As- or P-doped layer were comparable to that of a standard in-situ doped poly-crystalline layer after a dopant activation at 925°C for 10s.