Novel superjunction collector power SiGe HBTs with high thermal stability

In ord er to enhance the breakdown voltage of SiGe HBTs for high power application, the model of NPN SiGe HBT with superjunction collector is established with SILVACO TCAD. It is shown that the superjunction collector with iteratively vertical P layers and N layers will build up a lateral electric field to change the distribution of the electric field, reduce the peak ionization coefficient, and therefore enhance the breakdown voltage. However, the thermal effects of the device becomes more obviously as the voltage increases, which will lead to the thermal instability and hence limit the power handling capability of the device. Therefore, the layout of non-uniform finger spacing is further designed for thermal stability improvement. The increasing of the central finger spacing could effectively suppress the heat flow from adjacent fingers and enhance the thermal stability of novel device for power application.