LBIC INVESTIGATION OF PHOSPHORUS GETTERED MULTICRYSTALLINE SILICON WAFERS

Abstract

In multicrystalline silicon the interaction of dissolved impurities with extended crystallographic defects limits the effective minority carrier diffusion lengths Ln. External gettering by phosphorus diffusion near the surface is used to remove metallic impurities from the bulk of P type silicon wafers. It was found that Ln increases drastically after gettering at 850°C for 120 or 240 mn. SIMS analysis indicates that iron, copper and nickel are accumulated in the phosphorus doped regions and LBIC scan maps at λ = 940 nm indicate that the improvement of Ln results of the neutralization of intragrain and grain boundary recombination centers. It is concluded that phosphorus gettering removes dissolved and segregated impurity atoms.