The Application of Ion Implantation to the Study of Diffusion of Boron in Silicon
Implantations of10B were employed in conjunction with analysis of B depth distributions with the nuclear reaction,10B(n,4He)7Li, to investigate the diffusion of B in Si in the temperature range 900 to 1100°C for times of the order of 30 to 120 minutes. The diffusion constant, D, in Si was found to depend upon the B concentration. In order to evaluate the dependence of D upon B concentration, a series of isoconcentration experiments were conducted in which a “flat”11B distribution was produced by multiple energy ion implantations followed by a “tracer” implant of 10B. At 1000°C and a B concentration of 1020 cm-3, D is an order of magnitude larger than the intrinsic value of 1.5x10-14 cm2/sec. In Si heavily doped with As(2×1020cm-3), the diffusivity of B is an order of magnitude lower than the intrinsic value. These results can be interpreted by a model in which the B diffusivity in Si is a function of the Fermi level.
KeywordsDiffusion Constant Hole Concentration Intrinsic Diffusivity Multiple Energy Tion Diffusion
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