Exploiting energy sequencing of low energy SIMS to determine intrinsic chemical profiles with sub-nm precision

In the past, it has been proposed that secondary ion mass spectrometry (SIMS) depth profiling of a sample using a range of beam energies could be used as a means of estimating the intrinsic sample profile by extrapolating the measured profile parameters back to zero beam energy. In this paper, the a...

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Veröffentlicht in:Journal of vacuum science and technology. B, Nanotechnology & microelectronics Nanotechnology & microelectronics, 2018-05, Vol.36 (3)
Hauptverfasser: Morris, Richard J. H., Hase, Thomas P. A.
Format: Artikel
Sprache:eng
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Zusammenfassung:In the past, it has been proposed that secondary ion mass spectrometry (SIMS) depth profiling of a sample using a range of beam energies could be used as a means of estimating the intrinsic sample profile by extrapolating the measured profile parameters back to zero beam energy. In this paper, the authors address some of the issues that have hindered this approach and demonstrate a new metrology that exploits the idea of energy sequencing to yield intrinsic sample features with subnanometer precision. A significant reason why energy sequencing has not been exploited fully to date is because previous attempts failed to consider the convolution between the sample feature and response function parameters. Their new metrology overcomes this by utilizing a simultaneous fitting approach for which the sample feature is shared across all the profile fits and only the energy dependent response function parameters are varied between profiles using a power law dependence. The authors demonstrate how this approach now allows the intrinsic sample feature to be resolved robustly and with high precision. Additionally, the authors also show that once a specific matrix response function power law dependence has been established, as few as two SIMS profile energies would be sufficient to accurately determine the intrinsic sample feature. This new metrology approach is demonstrated using an atomically sharp SiGe/Si interface and was benchmarked against atomic resolution high angle annular dark field-scanning transmission electron microscopy.
ISSN:2166-2746
2166-2754
DOI:10.1116/1.5019644