Journal of Vacuum Science & Technology B, Vol.16, No.1, 377-381, 1998
Quantification of secondary-ion-mass spectroscopy depth profiles using maximum entropy deconvolution with a sample independent response function
We describe a new method for extracting the secondary-ion-mass spectroscopy response function from measured data for Slayers. The method was developed to reduce the danger of incorporating sample dependent behavior in the response, and is particularly appropriate for use with sub-keV profile energies where the depth resolution is so high that structure can be observed in layers with nm-scale thickness. We demonstrate this method on a system of variously spaced boron delta layers grown in silicon by molecular beam epitaxy. The deconvolved boron distributions for different primary ion beam energies, ranging from 500 eV to 6 keV, appear to be self-consistent and the corresponding depth resolutions are all increased significantly. Deltas with a 2 nm spacing are resolved without deconvolution using a normally incident 250 eV O-2(+) beam and the depth resolution (Rayleigh criterion) achievable under these conditions with deconvolution is <1 nm. Segregation of boron at the near surface side of the delta layers is clearly visible in these deconvolved data. These features would have been removed using an uncorrected response.