Gettering thresholds for transition metals by oxygen-related defects in silicon

This letter reports a qualitative study of the gettering of technologically important transition metal contaminants by a wide variety of distributions of oxygen precipitates and related defects in silicon. Various metals were diffused into specially prepared silicon wafers containing densities of oxygen precipitates ranging between 105 and 2×1010 cm−3. The precipitates were of a variety of sizes both with and without punched-out dislocation networks and associated stacking faults. Following previous work and using the Haze Test to monitor gettering activity, a threshold in precipitate density has been determined for the complete gettering of Cu and Ni (about 1×105 and 3×106 cm−3, respectively). No influence of precipitate size (above an as yet to be determined minimum) or of the presence of punched-out dislocations or stacking faults could be determined for these two metals, the fastest diffusing of the 3d group. Comments on the gettering of Fe are made.