DEFECTS AND VOIDS IN HE-IMPLANTED SI STUDIED BY SLOW-POSITRON ANNIHILATION AND TRANSMISSION ELECTRON-MICROSCOPY()

The distribution and annealing behavior of defects in crystalline sili con caused by 7x10(16)/cm(2) He+ implantation were investigated by slo w-positron annihilation technique, transmission electron microscopy, R utherford backscattering, and channeling spectroscopy. It was found th at small vacancy clusters were induced in the surface region and big c lusters (microbubbles) formed around the projected range in which the crystal was heavily damaged by the implantation. The small vacancy clu sters in the near-surface region start to disappear at 300 degrees C a nd can be removed at temperatures up to 700 degrees C by dissociation and diffusing to the damaged region. This results in the growth of voi ds. The severely damaged region around the projected range begins to a nneal out at temperatures higher than 600 degrees C, and He is release d, leaving voids embedded inside the crystalline silicon.