Delay time constant analysis for f/sub /spl tau// optimization in RF Si/SiGe bipolar devices

This work describes an approach for f/sub /spl tau// optimization in RF Si/SiGe bipolar devices by analyzing the delay time components that contribute to the overall transistor speed. Using the proposed parameter extraction method, all delay time constants can be obtained. Subsequently, identifying and minimizing the limiting time delay can effectively improve f/sub /spl tau// of the bipolar devices. Using AKM's Si-BJT technology as a case study, the optimization of the SiGe epitaxial base, intrinsic collector and base doping profiles, and extrinsic collector resistance is demonstrated.