The interstitial fraction of diffusivity of common dopants in Si

The relative contributions of interstitials and vacancies to diffusion of a dopant A in silicon are specified by the interstitial fraction of diffusivity, f(A). Accurate knowledge of f is required for predictive simulations of Si processing during which the point defect population is perturbed, such as transient enhanced diffusion, While experimental determination of f(A) is traditionally based on an underdetermined system of equations, we show here that it is actually possible to derive expressions that give meaningful bounds on f(A) without any further assumptions but that of local equilibrium, By employing a pair of dopants under the same point-defect perturbance, and by utilizing perturbances very far from equilibrium, w e obtain experimentally f(Sb)less than or equal to 0.012 and f(B) greater than or equal to 0.98 at temperatures of similar to 800 degrees C, which are the strictest bounds reported to date, Our results are in agreement with a theoretical expectation that a substitutional dopant in Si should either be a pure vacancy, or a pure interstitial(cy) diffuser. (C) 1997 Americaan Institute of Physics. [S0003-6951(97)03152-5].