The transient enhanced diffusion of B in pre-amorphized and re-grown material was studied by using secondary ion mass spectrometric and transmission electron microscopic techniques. A comparison was made of 4keV B implantation (1014/cm2) into crystalline and Ge+ pre-amorphized samples. Upon annealing, the B-implanted crystalline material exhibited the familiar transient enhanced diffusion. In this case, the peak of the B distribution was relatively immobile and only the B in the tail exhibited transient enhanced diffusion. In the case of the other samples, the surface was first pre-amorphized by implantation with 180keV Ge+ (1015/cm2). This produced an amorphous layer that was 230nm deep and which was then implanted with B. After implantation, the tail of the B distribution extended to only 70nm. Upon annealing, transient enhanced diffusion of B in the re-grown material was also observed, but the diffusion profile was very different. In this case, the peak exhibited no clustering and the entire profile diffused. The time which was required for the transient enhanced diffusion to decay was equal to about 0.25h at 800C. The transmission electron microscopic results indicated that (311) defects in the end-of-range damage stopped dissolving within 600s to 1h at 800C. These results indicated that, under these pre-amorphization conditions, not only did the end-of-range defects not block the flow of interstitials into the re-grown material, the (311) defects in the end-of-range damage acted as sources of interstitials. In addition, B did not appear to cluster in re-grown material.

Diffusion of Ion Implanted Boron in Preamorphized Silicon. K.S.Jones, L.H.Zhang, V.Krishnamoorthy, M.Law, D.S.Simons, P.Chi, L.Rubin, R.G.Elliman: Applied Physics Letters, 1996, 68[19], 2672-4