Annealing behavior of crystalline Si implanted with high dose of protons

Single crystal silicon wafers have been implanted by 5 × 10¹⁶ cm^-2 H⁺ ions at an energy of 140 keV at room temperature. After cutting, the samples were annealed at temperatures ranging from 200 to 900°C for 30 min and examined by Rutherford backscattering and channeling spectroscopy, and cross-sectional transmission electron microscopy. The results indicate that the extended defects induced by high-dose H⁺ implantation are stable below 400°C. Annealed at temperatures higher than 450°C, these complex defects can be reduced and most of the initial radiation damage converts into voids at 900°C. Thermal treatment at T ≥ 450°C produces blisters and flakes on the sample surface, resulting in the lattice distortion of the surface layer. The results have been interpreted by the assumption of the formation of H₂ and microbubbles at T ≥ 400°C in high dose H⁺-implanted Si.