SiGe HBT module with 2.5 ps gate delay

We present a double-polysilicon SiGe:C HBT module showing a CML ring oscillator (RO) gate delay tau of 2.5 ps, and f
_T
/ f
_max
/BV
_CEo
values of 300 GHz/350 GHz/1.85V. A key new feature of the HBT module is a connection of the extrinsic and intrinsic base regions by lateral epitaxial overgrowth. This facilitates simultaneously a very low base resistance and a reduced base-collector capacitance. In addition, the RF performance is enhanced for devices rotated by 45deg with respect to the standard orientation due to favorable epitaxial growth behavior.