Surface damage in silicon co-implanted with He and H ions: Effect of H implant energy

Cz n-type Si (100) wafers were singly or sequentially implanted with 160 keV He ions at a fluence of 5 × 1016/cm2 and H ions at a fluence of 1 × 1016/cm2 with different energies of 40, 110 and 160 keV, respectively. Surface damage, defect microstructures as well as H diffusion have been studied. Our results clearly show that depending on H energy, sequential implantation of He and H into Si could induce a series of surface features upon annealing. Localized surface exfoliation with thickness corresponding to H ion range is observed in He and 40 keV H ion co-implanted Si after annealing at temperatures of 600 °C and above, while large area exfoliation appears on the 110 keV H co-implanted Si surface at a depth close to the He ion range upon high temperature annealing. However, no clear surface damage is found on the post 160 keV H implanted and annealed Si. Results from transmission electron microscopy observations reveal that the post H ion implantation at different energies plays quite different role in thermal growth of He-induced micro-defects. The observed surface phenomena have been interpreted based on the defect creation, its evolution as well as H diffusion.