PC Zalm
Quantitative considerations in medium energy ion scattering depth profiling analysis of nanolayers
Zalm, PC; Bailey, P; Reading, MA; Rossall, AK; van den Berg, JA
Authors
P Bailey
MA Reading
AK Rossall
JA van den Berg
Abstract
The high depth resolution capability of medium energy ion scattering (MEIS) is becoming increasingly relevant to the characterisation of nanolayers in e.g. microelectronics. In this paper we examine the attainable quantitative accuracy of MEIS depth profiling. Transparent but reliable analytical calculations are used to illustrate what can ultimately be achieved for dilute impurities in a silicon matrix and the significant element-dependence of the depth scale, for instance, is illustrated this way. Furthermore, the signal intensity-to-concentration conversion and its dependence on the depth of scattering is addressed. Notably, deviations from the Rutherford scattering cross section due to screening effects resulting in a non-coulombic interaction potential and the reduction of the yield owing to neutralization of the exiting, backscattered H+ and He+ projectiles are evaluated. The former mainly affects the scattering off heavy target atoms while the latter is most severe for scattering off light target atoms and can be less accurately predicted. However, a pragmatic approach employing an extensive data set of measured ion fractions for both H+ and He+ ions scattered off a range of surfaces, allows its parameterization. This has enabled the combination of both effects, which provides essential information regarding the yield dependence both on the projectile energy and the mass of the scattering atom. Although, absolute quantification, especially when using He+, may not always be achievable, relative quantification in which the sum of all species in a layer adds up to 100%, is generally possible. This conclusion is supported by the provision of some examples of MEIS derived depth profiles of nanolayers. Finally, the relative benefits of either using H+ or He+ ions are briefly considered.
Citation
Zalm, P., Bailey, P., Reading, M., Rossall, A., & van den Berg, J. (2016). Quantitative considerations in medium energy ion scattering depth profiling analysis of nanolayers. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 387, 77-85. https://doi.org/10.1016/j.nimb.2016.10.004
Journal Article Type | Article |
---|---|
Acceptance Date | Oct 5, 2016 |
Online Publication Date | Oct 14, 2016 |
Publication Date | Oct 14, 2016 |
Deposit Date | Dec 1, 2016 |
Publicly Available Date | Dec 1, 2016 |
Journal | Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms |
Print ISSN | 0168-583X |
Publisher | Elsevier |
Volume | 387 |
Pages | 77-85 |
DOI | https://doi.org/10.1016/j.nimb.2016.10.004 |
Publisher URL | http://dx.doi.org/10.1016/j.nimb.2016.10.004 |
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Licence
http://creativecommons.org/licenses/by/4.0/
Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/
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