Broad-band and wireless communication seem to be a technology battlegr
ound, with new high performance demands to the applied active and pass
ive devices, and the optimization of circuit design. Up to now, there
are several technologies for low power and low noise or high speed app
lications, e.g. the advanced silicon bipolar transistor, III-V HBTs, H
EMTs, and MODFETs. In this paper, the advantage of Si/SiGe HBTs are pr
esented and discussed with a view to their fabrication in a low-cost m
ass production technology. For further increasing the performance of t
he Si/SiGe HBT, the vertical doping profile and the lateral structure
need to be optimized. Utilizing new low temperature ultra-scaled fully
self-aligned integration concepts, a Si heterojunction bipolar device
can be achieved featuring high package density, good passivation and
long term stability.