Platinum diffusion at low temperatures

In a series of experiments, the diffusion of platinum in silicon was investigated at low temperatures in the range from 700 deg. C to 800 deg. C. Depth profiles measured in as-grown float zone (FZ) silicon were found to differ strongly from those in as-grown Czochralski (CZ) silicon. These differences as well as different profiles measured in various FZ wafers after identical processing can be attributed to different initial concentrations of intrinsic point defects. In general, platinum depth profiles were found to agree qualitatively with the predictions of standard diffusion theories, but not quantitatively. Therefore, parameters for platinum and point defect diffusion reported in the literature were modified to describe consistently the diffusion in both kinds of material.