Impact of extrinsic base process on NPN HBT performance and polysilicon resistor in integrated SiGe HBTs

We have explored the process window for polysilicon resistor in the self-aligned epi-base HBT process utilizing various structure and implant conditions. We have performed a systematic study on the effects of implant energy, dosage, and polysilicon structure on the polysilicon resistor, p-i-n diode, and NPN performance. We find that the properties of this resistor can be controlled via the implant conditions, while leaving key HBT figures of merit such as f/sub T/, f/sub max/ virtually unchanged. We also demonstrate conditions resulting in a precision, low TCR resistor.