The transient up-hill diffusion of Mg during annealing at 900C was computer-simulated. It was assumed that diffusion occurred via the substitutional-interstitial mechanism, with excess interstitials and vacancies being produced by implantation; thus causing the abnormal diffusion behavior. The substitutional-interstitial mechanism was shown to be mathematically equivalent to an existing interstitial-dopant pair diffusion model. This permitted the programme (a Si process simulator that included dopant/point-defect interactions) to be used to model up-hill diffusion if suitable diffusivity and defect parameters were included. The profiles of excess interstitials and vacancies which were produced by the implantation process were deduced from Boltzmann transport equation calculations. It was found that transient up-hill diffusion could be accurately simulated; with the dopant diffusing, from regions with excess interstitials, towards the surface or towards regions with excess vacancies. When the defect concentrations had returned to their steady-state levels, via diffusion, recombination, or capture by sinks, normal concentration-dependent diffusion into the substrate occurred.

H.G.Robinson, M.D.Deal, G.Amaratunga. P.B.Griffin, D.A.Stevenson, J.D.Plummer: Journal of Applied Physics, 1992, 71[6], 2615-23