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SIMS depth profile analysis of tribological coatings on curved surfaces

Influence of ion impact angle and take‐off angle on ion yield and on the quantitative analysis of chemical composition
 
: Schiffmann, K.I.

:

Surface and Interface Analysis (2019), Online First, 9 pp.
ISSN: 0142-2421
English
Journal Article
Fraunhofer IST ()
Cs-cluster; DLC; impact angle; nitrides; SIMS; take-off angle

Abstract
Quantitative analysis of chemical composition of materials by SIMS depth profiling is challenging due to strong matrix effects. However, by using the MCs+‐cluster method in conjunction with matched standards, a quite good quantification is possible. Another source of errors can be nonflat (curved) surfaces, which is often the case in coated parts of automotive or tool industry (injection needles, plungers, pistons, and drills). In such cases, the impact angle of the ion beam or the take‐off angle of the mass spectrometer can locally differ from that of a flat sample. This has influence on the ion count rates and therefore on the quantification. In this paper, we use the MCs+ method to analyze DLC, W‐DLC, CrN, TiN, TiAlN, and CrAlN coatings with respect to the influence of a tilt of the sample surface to the secondary ion yield and on the quantification of coating stoichiometry. Impact angle and take‐off angle have been varied in a wide range. It was found that ion intensities for nitridic systems vary by up to a factor of 30 when changing the impact angle of the ion beam, while for carbon‐based systems the maximum variation is only a factor of 2. Take‐off angle variations may change ion count rates by a factor of 5 up to 50. As a consequence, a tilt depending error in quantification of chemical composition of coatings may occur, which typically can be in the range of 5% to 20%, while it can increase up to 40% in some cases.

: http://publica.fraunhofer.de/documents/N-540731.html