Enhanced Annealing Effects in Boron-Implanted Layers in Silicon by Postimplantation of Silicon Ions

Various effects of postimplantation of silicon ions on boron-implanted layers are reported. The amount of enhanced annealing depends critically on the target temperature during implantation and on the dose of silicon ions used. At 100 keV, a 5×1015/cm2 silicon dose is necessary to create an amorphous layer extending up to the surface at room temperature. Close to 100% of the boron ions located in this layer become electrically active after annealing at 600°C. For boron doses approximately greater than 3×1015/cm2, shallow silicon implantations produce stronger enhanced annealing than expected. For boron doses less than 2×1014/cm2, little or no enhanced annealing is observed.