Vertical profile optimization of very high frequency epitaxial Si- and SiGe-base bipolar transistors

Abstract

Bipolar transistors with phosphorus-doped emitters and sub-50 nm epitaxial bases have been fabricated in a low thermal-cycle process to explore the trade-offs between cutoff frequency, breakdown voltage and Early voltage. Record peak f/sub T/s of 73 GHz for a Si BJT and 113 GHz for a SiGe HBT with respective /spl beta/V/sub A/ products of 630 and 48,400 V were obtained for intrinsic base sheet resistances of 26 and 7 k/spl Omega/spl square/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>