A SIMS study on the secondary ion yield in boron implanted silicon using a low energy primary oxygen beam

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Secondary ion yields (B+, B2+, B3+) have been measured for two kinds of boron implanted silicon, in which one was a boron supersaturated sample and the other was a boron precipitated sample. Under a low energy primary oxygen beam (E < about 3 keV), the secondary ion yields (B+, B2+, B3+) in the boron precipitated sample were higher than those in the supersaturated sample. However, no difference was recognized under 8 keV primary ion bombardment at a depth of less than 150 nm. This result shows that the secondary ion yield depends on the difference between dissolved and precipitated boron in silicon by low energy primary ion SIMS analysis. This gain in the B+ ion yield in the boron precipitated region under low energy ion bombardment may lead to a misunderstanding of the boron concentration profile. B2+ and B3+ ions have been found to be formed by a recombination process under 8 to 1.5 keV energy ion bombardment even in the boron precipitated region. These ion yields in the boron precipitated region are thought to be raised by the effect of the distance between the nearest neighboring boron atoms.