Platinum and gold diffusion monitor vacancy profiles induced into silicon wafers by aluminum alloying

Abstract

In this paper, we use the gold and platinum marker method, to confirm our preliminary finding that aluminum indiffusion into Si crystal during so-called aluminum gettering (AlG) can result in the injection of vacancies into Si crystal. Depth profiles of Au in p-type Si have been studied by the DLTS after diffusion at 850 degrees C for 2h prior to and subsequent to AlG. The donor concentration attributed to Aus is about two orders of magnitude higher compared with that measured in samples without AlG. Similar results were also observed for Pt. The increase in Pts or Aus concentration in the silicon bulk provides the most direct evidence so far that AlG with 400nm Al layer, for 50min at 1100 degrees C injects vacancies with non-equilibrium concentrations of about 1015cm3. The possible mechanism of vacancies generation is discussed.