Low-Temperature Formation of Palladium Silicided Shallow p⁺n Junctions Using Implant through Metal Technology

Excellent silicided shallow p⁺n junctions have been successfully achieved by the implantation of BF₂⁺ ions into thin Pd films on a Si substrate to a dose of 5×10¹⁵ cm^-2 and subsequent low-temperature (as low as 500° C) furnace annealing. The formed junctions have been characterized for the respective implantation conditions. In this experiment, the implant energy plays the key role in obtaining a low leakage diode. Reverse current density of about 1 nA/cm² and the ideality factor of about 1.03 can be attained by the implantation of BF₂⁺ ions at 100 keV and subsequent annealing at 600° C. The junction depth is about 0.08 µm, measured by the spread resistance method. As compared with the results of unimplanted specimens, the implantation of BF₂⁺ ions into a thin Pd layer can stabilize the Pd silicide film and prevent it from forming islands during high-temperature annealing. High-temperature stability of palladium silicides and the leakage current mechanism are also discussed in this report.