TCAD modeling of NPN-SiGe-HBT electrical performance improvement through extrinsic stress layer

Abstract

The impact of introducing an extrinsic stress layer to NPN-SiGe-HBT device on the electrical properties and frequency response has been studied using TCAD modeling. Simulations based on Hydrodynamic (HD) and Drift-Diffusion (DD) models have been carried out to clarify the influence of adding the extrinsic stress layer on the device electrical performance (static and dynamic). Simulation results show that NPN-SiGe-HBT device with extrinsic stress layer exhibit better frequency characteristics in comparison with equivalent conventional HBT device (without extrinsic stress layer). An approximately, 3% improvement in ft, and 5% improvement in fmax have been achieved. In addition to that, a decrease in the transit time of the device has been observed. That can be fully accounted to the influence of introducing the extrinsic stress layer on the device.