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

Abstract

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.

Initial activation behavior of boron at low temperatures with implantation doses below the amorphization threshold

“…Boron activation has been studied for several decades since the use of ion implantation as a doping technique for silicon integrated circuits. [6][7][8][9][10][11][12][13][14][15][16] Seidel and Mac Rae performed isochronal and isothermal annealing experiments to investigate boron activation in the temperature range of 400 °C-1000 °C. 7) Reverse annealing was observed with a medium implantation dose at temperatures ranging from 500 °C to 600 °C.…”