Model of backsurface gettering of metal impurities in silicon

Metallic impurities can degrade silicon devices in many ways, and various gettering techniques are therefore used to immobilize these atoms at the backsurface of the wafer. A solution to the relevent diffusion equations is given here and used to obtain a simple formula relating the gettered atom density to the gettering temperature and time with the metal diffusivity in silicon as the main input. The model reproduces experimental trends quite well.