THE MECHANISM OF IRON GETTERING IN BORON-DOPED SILICON

High-energy B implantation was used to introduce gettering layers into float-zone Si wafers contaminated with 2X10(14) Fe/cm(3). Secondary i on mass spectrometry shows that about 5% of the Fe contamination is co llected at the 4 mu m deep peak of a 4x10(14)/cm(2), 3.3 MeV B implant after annealing at 1000 degrees C for 1 h. Deep level transient spect roscopy demonstrates that increasing the gettering B dose from 4X10(12 ) to 4X10(14)/cm(2) reduces the Fe concentration from 3X10(12) to belo w similar to 10(10)/cm(3) in the 1-3 mu m deep region from the surface , indicating very efficient gettering. Measurements of the Fe depth pr ofile imply that the depletion of Fe near the gettering layer occurs u pon cooling down from 1000 degrees C. The gettering behavior can be qu alitatively understood in terms of a Fermi-level-enhanced pairing reac tion between Fe and B. (C) 1996 American Institute of Physics.