REEMISSION OF IRON ORIGINALLY GETTERED BY OXYGEN PRECIPITATES IN A SILICON-WAFER

We studied the thermal stability of Fe originally gettered by oxygen precipitates. After low-temperature annealing for gettering, we annealed at higher temperatures. We found that the Fe concentration increases faster in gettered wafers than as-grown wafers. This shows that Fe was re-emitted from the bulk defect region faster than surface Fe precipitates decomposed. The Fe concentration increases with annealing time to the solid solubility level at the temperature used. These results suggest that gettering and the re-emission of Fe are two parts of a reversible reaction.