Simulation of Al and phosphorus diffusion gettering in Si

We present a quantitative computer model ('Gettering Simulator') of phospho rus diffusion gettering (PDG) that allows to simulate the PDG process. The model was checked for Au as a typical substitutional metallic impurity elem ents and for Co as an example of the fast diffusing interstitial 3d metals in Si. Here we will only discuss the gettering of substitutional metals. Th e 'Gettering Simulator' includes a model for P diffusion for phosphorus con centrations [P] up to the solubility limit. In this model, the main contrib ution to phosphorus diffusion at [P] < 2 x 10(19) cm(-3) comas from the kic k-out mechanism, while at higher P concentrations the diffusion is dominate d by phosphorus vacancy complexes. The latter results in the development of the well-known 'kink-and-tail' P and specific self-interstitial profiles. The gettering mechanism is described by a combination of three factors: (1) the Fermi level effect; (2) the formation of phosphorus-metal pairs; (3) t he high concentration of self-interstitials in the bulk together with nearl y equilibrium concentration in the region of high phosphorus concentration near the surface. The third factor was found to be very important for the P DG of substitutional metals. No local equilibrium is assumed in the model. Instead. the calculations are based on the reaction rates between different species. (C) 2000 Elsevier Science S.A. All rights reserved.