A study of ultra-high performance SiGe HBT devices on SOI

The authors present a study of SiGe HBTs with F T >200GHz on an SOI substrate for the first time. The devices built on SOI exhibit a degradation of approximately 7 Ghz in Ft as compared with bulk devices while Fmax remains near 280 GHz. As expected, Ccs is reduced by ~ 40%. A loss of about 0.75 V in safe operating area is observed for the HBTs built on SOI, but approximately half of this can be regained by allowing the footprint to increase to the original, bulk-silicon HBT footprint by increasing the spacing from the collector to the deep trench isolation.