ABSTRACT
Recent advances [1-7] in state-of-the-art SiGe bipolar and BiCMOS technologies enabled impressive
transistor parameters like maximum oscillation frequencies of 285GHz [1], transit frequencies up to
350GHz [2] and ring-oscillator gate delay times down to 3.5 psec [5,7]. Therefore, even very high-
frequency applications like wireless LANs at 60GHz, optical communications at 80Gbit/sec and
automotive radar systems around 77GHz, which can now only be achieved by expensive III-V
technologies, seem to become feasible in a low-cost silicon-based technology in a highly integrated
manner. The progress in the high-speed performance of SiGe HBTs has been achieved by impurity
profile engineering in the SiGe base for improving forward transit time and base resistance as well as by
the development of self-aligned transistor architectures providing low parasitic capacitances and low
extrinsic series resistances. The different self-aligned emitter-base configurations, which are used in
present state-of-the-art SiGe HBT technologies, are requiring either nonselective epitaxial growth
(NSEG) [1,2,5] or selective epitaxial growth (SEG) [3,4,6,7] for the integration of the SiGe base.
