Influence of halo implant on leakage current and sheet resistance of ultrashallow p-n junctions

Sheet resistance and leakage current density of spike rapid thermal processed, millisecond flash annealed, and chemical vapor deposition (CVD) grown ultrashallow junctions (USJs) are compared with the contactless junction photovoltage technique for measurement of sheet resistance and leakage current (RsL) and four-point probe (4PP) techniques. A significant leakage current increase for USJs formed in halo-implanted profiles is explained by high electron and hole recombination generation in the near-surface end-of-range damaged layer enhanced by trap-assisted tunneling. The reduced thermal budget of millisecond annealing allows junction formation with reduced dopant diffusion and lower sheet resistance. However, when strong halo doping is employed, there is a significant increase in junction leakage current relative to that for junctions formed by spike annealing. This rise in leakage current can be reduced by annealing the halo implants before implanting the USJ or by lowering the halo implant dose. USJs ...