The mechanisms of iron gettering in silicon by boron ion-implantation

Boron implantation into silicon offers a unique system for studying the gettering mechanisms of Fe. The effectiveness of the gettering increases as the high-energy B ion implantation dose changes from 4E12 to 4E14 cm(-2), decreasing the Fe concentration in the near surface region to below the deep level transient spectroscopy detection limit of 1E10 cm(-3) Fermi level-induced Fe solubility enhancement and Fermi level-controlled Fe-B pairing combine to produce a relative partitioning for Fe as high as 10(6), for temperatures less than 400 degrees C, in high B-doped implanted regions adjacent to regions of low B bulk doping. Comparison studies show that in the time-temperature regimes typical of Si device fabrication, B gettering is more effective than gettering produced by Si implantation damage and more effective than trapping by a neutral impurity such as C.