Abstract: Through computer aided simulation and processing experiment,the structure parameters of Si/SiGe HBT were optimized carefully.An intrinsic space layer and a novel Ge fraction profile are used to reduce the influence of boron outdiffusion,base recombination and HBE.A SiGe HBT process compatible with conventional Si processes is developed,by which the SiGe HBT is fabricated successfully.The results of test indicated that the current gain β is 50 and the cut-off frequency f_T is 5.1 GHz.