Experimental Study of Internal Gettering Efficiency of Iron in Silicon

We have studied internal gettering efficiency of iron in silicon by Deep Level Transient Spectroscopy (DLTS) and standard lifetime – methods (SPV, PCD). Conventional high–low–high anneals were performed to produce a series of wafers with varying denuded zone (DZ) width and oxygen precipitation density. The wafers were intentionally iron contaminated to a level of about 3–5 ∗ 1013 cm−3. After contamination the wafers were annealed at 900 ◦ C and then slowly cooled to 850, 800, 750, 700 or 600 ◦ C. After cooling the remaining interstitial iron concentration was measured by SPV, -PCD and DLTS. The experimental results are compared with simulations. Our results indicate that with this contamination level, the gettering is effective only at temperatures below 750 ◦ C when iron is supersaturated over a factor of twenty. For temperatures above 750 ◦ C the gettering is limited by iron precipitation in the bulk.