Physically-based modeling of two-dimensional and three-dimensional implantation profiles: Influence of damage accumulation

The alteration of the shape of one-dimensional, two-dimensional (2D), and three-dimensional (3D) range distributions with growing dose as well as the extension of amorphous zones formed at high doses is studied for 15 keV BF₂ ⁺ and 30 keV P⁺ implantations into (100)Si using the dynamic binary collision code Crystal-TRIM. The range and damage profiles are calculated for the area 97.74 (parallel to [010]) × 97.74 (parallel to [001]) nm² at the target surface irradiated by the ion beam and surrounded by impenetrable masks. The change of the shape of the 2D and 3D distributions in the lateral direction is less pronounced than in the depth direction. At low doses the lateral profile branches are determined by rechanneled particles, at high doses the enhanced dechanneling is the reason for the increased lateral straggling. The latter effect is responsible for the relatively large lateral extension of the amorphous zone beneath the masks. The simulated depth profiles of boron and phosphorus and the predicted thickness of the amorphous layer are in good agreement with experimental data.