Element‐Specific broadening effects in SIMS depth profiling of light impurities implanted in silicon

Beam‐induced broadening effects in SIMS depth profiling have been studied for eight impurities (Li through Al) implanted in amorphized silicon at energies between 1 and 15 keV. Depth profiling was performed under Ar + (⩽2.5 keV) or O   2 +(⩽3 keV) impact. In selected cases (Li, N) the effect of the probe energy has also been investigated. The measured profiles show exponential tails. The decay length γ characterizing these tails exhibits strong oscillations when plotted as a function of the atomic number of the dopant. Maxima are seen for N and O (γ ≃ 7 nm) as well as for Mg (γ ≃ 13 nm), minima for B and Na (γ ≃ 2 nm). The results suggest that the observed effects are due to a yet unpredictable combination of collisional mixing, defect‐assisted diffusion and selective sputtering.