Phosphorus junctions, having depths ranging from 80nm to 0.005mm, were produced in wafers by means of thermal pre-deposition and drive-in heating. The wafers were then implanted with Si ions in order to create lattice damage both below and above the amorphization threshold. Subsequent heat-treatment led to recovery of the damage which was produced by implantation. The resultant excess interstitials favored enhanced dopant diffusion. Anomalous diffusivity was associated with non-amorphizing implants, regardless of the depth of the junction with respect to that of the damaged region. On the other hand, negligible or strong anomalous diffusivity was found after amorphizing implants, depending upon whether the initial P junction was shallower or deeper than the amorphous/crystalline interface. The asymmetric behavior of the P diffusivity, across the interface between amorphous and crystalline Si, was confirmed by using secondary ion mass spectrometry to profile an ion-implanted uniformly doped wafer. The enhanced diffusion was closely related to changes in the implant damage during furnace heating.

P.Negrini, M.Servidori, S.Solmi: Philosophical Magazine A, 1990, 61[4], 553-61