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The Accuracy of Al and Cu Film Thickness Determinations and the Implications for Electron Probe Microanalysis

Published online by Cambridge University Press:  27 April 2018

Mike B. Matthews ,
Stuart L. Kearns  and
Ben Buse
Mike B. Matthews*
Affiliation:
AWE, Aldermaston, Reading RG7 4PR, UK University of Bristol, School of Earth Sciences, Wills Memorial Building, Queens Road, Clifton BS8 1RJ, UK
Stuart L. Kearns
Affiliation:
University of Bristol, School of Earth Sciences, Wills Memorial Building, Queens Road, Clifton BS8 1RJ, UK
Ben Buse
Affiliation:
University of Bristol, School of Earth Sciences, Wills Memorial Building, Queens Road, Clifton BS8 1RJ, UK
*
Author for correspondence: Mike B. Matthews, E-mail: matthm@hotmail.com
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Abstract

The accuracy to which Cu and Al coatings can be determined, and the effect this has on the quantification of the substrate, is investigated. Cu and Al coatings of nominally 5, 10, 15, and 20 nm were sputter coated onto polished Bi using two configurations of coater: One with the film thickness monitor (FTM) sensor colocated with the samples, and one where the sensor is located to one side. The FTM thicknesses are compared against those calculated from measured Cu Lα and Al Kα k-ratios using PENEPMA, GMRFilm, and DTSA-II. Selected samples were also cross-sectioned using focused ion beam. Both systems produced repeatable coatings, the thickest coating being approximately four times the thinnest coating. The side-located FTM sensor indicated thicknesses less than half those of the software modeled results, propagating on to 70% errors in substrate quantification at 5 kV. The colocated FTM sensor produced errors in film thickness and substrate quantification of 10–20%. Over the range of film thicknesses and accelerating voltages modeled both the substrate and coating k-ratios can be approximated by linear trends as functions of film thickness. The Al films were found to have a reduced density of ~2 g/cm2.

Keywords

aluminumcopperbismuththin filmfilm thickness
Type
Materials Science Applications
Information
Microscopy and Microanalysis , Volume 24 , Issue 2 , April 2018 , pp. 83 - 92
Copyright
© Microscopy Society of America 2018 

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