Discussion On Simulation And Calibration Method Of 0.35 - Micron Germanium - Silicon HBT Process And Device

SiGe HBT device is fabricated by introducing Germanium into the base region, Germanium is a material of narrow width forbidden band which makes the final forbidden band width of base narrower than emitter, Germaniun also makes the junction of emitter to be hetero junction. The carrier transient time in base region is reduced by this change, so we can get higher gain and cutoff frequency at the same time.Many of the developers are using TCAD in the process of developing SiGe HBT technology to reduce the cost of wafers for experiment and speed up products to market. The difficulties are how to simulate SiGe in process and device part, how to calibrate the simulated results when they are away from the measurement. In this thesis, we present how to simulate the full process and device flow of a SiGe HBT device coming from a 0.35 BiCMOS process, and discuss the calibration methodology to calibrate the final process structures and device characteristics versus measurement.In the process simulation part, the stress dependent oxidation model is used for LOCOS simulation, and the most advanced point defect models, the activation model, segregation model and dose loss model are used for diffusion. The property of SiGe material and diffusion of dopant in SiGe are also simulated to form the final device structure. And in the device simulation part, the famous mobility models, generation and recombination models are introduced, including the method to simulate most of the DC characteristics and frequency related characteristics.Regarding calibration, online process calibration is very important to make sure that every input is correct comparing with the online data. The doping profile calibration is the key task for process simulation, user need to make more effort to make the profiles as close as possible to measurement. Use CV data to calibrate the shallow junction is proved to be a very good method here. In device calibration part, the key method is to analysis the electrical phenomena, add correct models, and then tune the model parameters to fit the measured curves. In this thesis, we’ve calibrated Gummel curve, ICVC curve, BVceo curve, BVcbo curve and BVebo curve, also including the calibration of cutoff frequency.The final calibrated results are very good. The predicted results of the similar devices under different process condition are very close to the measurement. The process of the simulation and the method of calibration should provide readers a startup and reference to simulate and develop SiGe HBT devices.