The anomalous damage behavior of BF 2+ implantation into silicon at 300 and 77 K is investigated by using grazing‐angle Rutherford backscattering and channelling combined with transmission electron microscopy. The damage or the amorphous layer produced by BF+2 implantation is different from that produced by other heavier (than 27Al+) ions. For BF+2 implantation at 300 K, there are two damage peaks, one at a depth near the projectile range of the ions, the other near the surface. For BF+2 implantation at 77 K, the damage or the amorphous layer first occurs at the surface, then the amorphous layer extends into the bulk of silicon with increasing dose.