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

The initial behavior of boron activation at low temperatures was experimentally studied at implantation doses below the threshold for amorphization of the silicon substrates. A test structure was developed to analyze the activation in the early stage of annealing at temperatures below 400 °C. Saturation of the activation level following the decay of the activation rate was observed during annealing for long times at temperatures between 350 °C and 400 °C. Boron activation was enhanced due to the channeling effect of the implanted boron ions when the implantation tilt angle was reduced from 7° to 0°. However, the active boron percentage declined with increasing implantation dose. Boron activation was degraded by silicon implantation at low doses following the boron implantation. The low activation energies extracted from the experimental data indicated that boron activation was limited by the metastable defect complexes under subamorphizing implantation.