Influence of nickel precipitation on the formation of denuded zone in Czochralski silicon

摘要

The influence of nickel precipitation on the formation of denuded zone (DZ) in Czochralski silicon (Cz Si) was systematically investigated by means of Scanning Infrared Microscopy (SIRM) and optical microscopy (OM). It was found that, for conventional high-low-high annealing (CFA), the DZ can be obtained in all specimens contaminated by nickel impurity at different steps of the heat treatment, indicating that no nickel precipitates generated in the region just below the surface. Additionally, the width of the DZ is nearly the same in all specimens although the contamination sequence is different, indicating that the contamination temperature, that is, the corresponding equilibrium concentration of interstitial nickel in the silicon doesn't influence significantly the thermodynamics and kinetics process of the formation of nickel precipitates. For Rapid thermal annealing (RTA)-low-high annealing, the tendency remained unchanged. On the basis of the experimental results, it is supposed that the formation of DZ is strongly influenced by the segregation gettering and intrinsic gettering of the nickel atoms, which were caused by the formation of nickel-silicon (Ni-Si) alloys close to the surface, oxygen precipitates and extended defects in the bulk, respectively.