THE EFFECT OF FLUORINE ON THE REDISTRIBUTION OF BORON IN ION-IMPLANTED SILICON

The distributions of B atoms in samples previously implanted with F+ and Ne+ with doses of 1.2 x 10(13) cm-2 and 1.5 x 10(15) cm-2 before and after annealing were investigated by secondary ion mass spectrometry. After annealing at 900-degrees-C, a strong dependence of B redistribution rate on F concentration was shown. The presence of F decreased B redistribution, while that of Ne (close to F in the periodic table, but inert) did not. When postimplantation annealing was carried out at 1000-degrees-C, the B distribution did not depend on the type of the previously implanted ions. At this temperature F atoms exit the crystal. The experiment showed that the redistribution of B implanted in Si depended on the chemical activity of the impurity present in a crystal and on its concentration.