The anomalous damage behaviour of BF2+ implantation into silicon at 300K and 77K has been investigated by using grazing angle Rutherford backscattering and channeling in combination with transmission electron microscopy.The damage or the amorphous layer produced by BF2+ implantation is different from that produced by other heavier ions(>27Al+). For BF2+ implantation at 300K
there are two damage peaks
one at a depth near the projectile range of the ions and the other at the near surface
while for BF2+ implantation at 77K
the damage or the amorphous layer first occurs at the surface and is then extended to the bulk of silicon with increasing dose.