Dislocations (of interstitial character) as well as cavities were known for their ability to getter impurities within Si. In order to determine the relative gettering strength both dislocations and cavities were produced at different depths within (100) Si. This was obtained by implantation and subsequent annealing of 3 x 1016 (40keV H)/cm2 and 1016 (140keV Si)/cm2 resulting in cavities and dislocations at depths of 400 and 200nm, respectively. Fe or Cu was then implanted with a dose of 5 x 1013/cm2 and an energy of 35keV. By selective implantation of different areas, all possible combinations of impurities, dislocations and cavities were obtained within one Si-sample. The results show, clearly, that Cu-impurities were gettered totally by cavities (or open-volume defects), even when dislocations were also present. In contrast, Fe-impurities, which were released from traps near the surface during annealing, were gettered by both interstitial-based dislocations and open-volume defects. Secondary ion mass spectrometry and transmission electron microscopy analyses reveal defect-Fe-impurity interactions at the different trap sites.

Efficiency of Dislocations and Cavities for Gettering of Cu and Fe in Silicon. B.Stritzker, M.Petravic, J.Wong-Leung, J.S.Williams: Nuclear Instruments and Methods in Physics Research B, 2001, 175-177, 154-8