The reduction of base resistance of SiGe/Si HBT via ion implantation and side-wall oxide self-aligned technique

Ion implantation and the side-wall oxide self-aligned technique was used to reduce the extrinsic base resistance of a SiGe HBT. The sheet resistance of the SiGe layer was reduced over 20 times under proper implantation and annealing parameters, and ohmic contacting was also improved. This can greatly enhance the frequency performance and reduce the noise figure of SiGe HBT. The SiGe sheet resistance is sensitive to the implantation and annealing parameters. For our samples an implantation dose of 10/sup 16//cm/sup 3/ and energy of 35 kev, annealing temperature from 960/spl deg/C to 1000/spl deg/C is suitable.