Effects of hydrogen plasma treatment on cavity formation in silicon induced by He ion implantation

The effects of hydrogen plasma treatment on He-implantation-induced cavities in silicon during subsequent annealing were studied. Silicon samples were first implanted at room temperature with He ions of different energies (40, 160 and 1550 keV) at the same dose of 5 x 1016 cm2, and then were exposed to high density ECR hydrogen plasma for 30 min at temperature of 250 degree C. XTEM was applied to study the formation of cavities after an annealing at 800 degree C for 1 h. The results clearly show that the effects of plasma hydrogenation on thermal growth of cavities depend strongly on the He ion energy. No effects were clearly seen in 40 keV He-implantation-induced cavities and a slightly effects were observed in that of 1550 keV He implantation. However, in the case of 160 keV He implantation, additional H plasma treatment could assist the growth of cavities. Further analyses show that the effects were possibly related to the role of hydrogen introduced by plasma hydrogenation. (authors)