Characterization of helium bubbles in Si by a slow positron beam

Maekawa, Masaki; Kawasuso, Atsuo

The helium bubble formed in silicon by the high-dose helium ion implantation was observed by the positron annihilation method. The peak intensities of annihilation rays (S parameter) and its annealing behaviors were measured. At as-implanted state, S parameter increased because of the implantation defects. After 300C annealing, S parameter decreased by the helium bubble. After 900C annealing, S parameter increased drastically due to the microvoids formed by the desorption of helium atoms. Positron annihilation method can detect the generation and disappearance process of the helium bubble by the ion implantation.