Elimination of secondary defects in preamorphized Si by C+ implantation

Abstract

In preamorphization of Si, secondary defects formed at the original amorphous/crystal (a/c) interface were studied as a function of the dose of carbon ion implantation. The preamorphized depth was 230 nm. The carbon was implanted at 78 or 90 keV at 2×1012–2×1015/cm2. The size and density of dislocation loops near the a/c interface decreased with increasing C+ dose. The C+ implantation at a dose of 1×1015/cm2 reduced the density of atoms bound by dislocation loops from 5.9×1014/cm2 to 2.6×1013/cm2. At C+ doses higher than about 1×1015/cm2, additional defects with a diameter of less than about 5 nm were observed. These defects are SiC agglomerates that act as a sink for excess self-interstitials, which results in a reduction in the density of secondary defects.