Anomalous diffusion and gettering of transition metals in silicon

By using metallic haze to detect the presence of transition metals in silicon, and rapid thermal annealing to thermally process wafers, anomalous diffusion and gettering of transition metals in silicon have been observed. Gettering is observed over a wide temperature range (300 –1100 °C) and anneal duration (1–300 s). The rapid initial gettering is found to occur over mechanical and laser damaged areas but not over polycrystalline silicon backsealed regions. Surface diffusion is found to dominate over anomalous bulk diffusion at the lower temperatures investigated.