This paper starts out by summarising the modelling and computer simulation of phosphorus diffusion gettering (PDG) of Au. The mobilisation of precipitated impurity atoms is discussed in the light of the silicon interstitial supersaturation provided by the phosphorus diffusion (PD). We then extend the gettering model to Co using bulk solubility data of highly P-doped Si, and find satisfactory agreement with experimental profiles of the total Co-concentration. Yet the pointed disagreement between the CoP/Co-g-ratio obtained through simulation and Mossbauer data leads to the conclusion that, in the case of phosphorus silicate glass (PSG) growth, segregation alone cannot unambigiously account for the observed gettering efficiency. Instead, it is proposed that PID induced silicide formation provides a more suitable explanation of the high efficiency of PDG accompanied with PSG growth. (C) 2002 Elsevier Science B.V. All rights reserved.