RF performance tradeoffs of SiGe HBT fabricated by reduced pressure chemical vapor deposition

In this paper we developed high cutoff frequency and low noise SiGe HBT devices using reduced pressure chemical vapor deposition (RPCVD) process of low cost and high throughput. In addition the RPCVD can alleviate large thermal variation even on a single wafer as occurs in ultra-high vacuum chemical vapor deposition (UHVCVD) process. We also adopted the cheap localized oxidation of silicon (LOCOS) instead of shallow trench for the isolation of terminals to reduce the parasitic from linkage at RF arena. The cutoff frequency and maximum oscillation frequency of SiGe HBT having the emitter size of 1×2.5 μm² were 48 and 62 GHz, respectively. With the tradeoff of base profile and adopting finger-type base structure the measured minimum noise figure of 1.5 dB and associated gain of 16 dB at 1.5 GHz consuming the collector current of 3.1 mA were also observed in the low noise device. Limitation of noise performance related with this process was also discussed.