Influence of Interconnect Parasitics on the Lateral Scaling of SiGe Power HBTs

The influence of interconnect parasitics on the lateral scaling of emitter stripe width of large-area SiGe power heterojunction bipolar transistors (HBTs) are analytically studied and experimentally verified. It is found that, due to the increased parasitics along with the increase of device area, the maximum oscillation frequency (fmax ) of a power SiGe HBT cannot be improved monotonically with the shrinking of the emitter stripe width, which is different from the downscaling of the low-power (few emitter stripes) counterparts. Instead, the emitter stripe width of large-area devices ought to be appropriately up-scaled, relative to that of low-power devices, in order to optimize the RF performance of large-area SiGe power HBTs. It is also found that the influences of interconnect parasitics on the fmax and the power gain (Gmax) for common-emitter (CE) and for common-base (CB) SiGe power HBTs are different