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- XPS (3)
- Calibration (2)
- Ellipsometry (2)
- SAXS (2)
- Silicon dioxide (2)
- TEM (2)
- Thickness (2)
- Thin films (2)
- Analytical quality assurance (1)
- Attenuation length (1)
Organisationseinheit der BAM
Nanotechnologien werden gegenwärtig als leistungsfähige Oberflächentechniken in erheblichem Umfange industriell genutzt. Dabei spielen dünne Schichten und deren Kenndaten eine wesentliche Rolle, z.B. als Röntgenspiegel oder optische und magnetooptische Datenträger. Die Schichtdicke zählt hierbei zu den technologisch wichtigen Parametern. Abgeleitet von Anwenderinteressen, werden für die Röntgenreflektometrie (XRR bzw. GIXR), Elektronenstrahl-Mikroanalyse (EPMA) und Röntgenfluoreszenzanalyse (XRF) einerseits und die Ellipsometrie andererseits zugeschnittene Schichtdickenmaßverkörperungen (SDM) entwickelt, gefertigt und untersucht. Das Ziel ist die Bereitstellung praxistauglicher, kalibrierter SDM, im weiteren Schichtdickennormale (SDN) genannt. SDN sind Maßverkörperungen, für die der Schichtdickenwert mit einer definierten Messunsicherheit bekannt und auf ein metrologisch anerkanntes Längennormal zurückgeführt ist. Berichtet wird über die Herstellung und messtechnische Charakterisierung der beiden spezifischen Varianten von Maßverkörperungen.
The first hard X-ray beamline at BESSY II will be installed by BAM and PTB at a superconducting 7 T wavelength shifter. The main optical elements of the beamline are a Double-Multilayer-Monochromator and a Double-Crystal-Monochromator. The two devices can be used separately or in-line. Main applications of monochromatic radiation with photon energies up to 50 keV are X-ray fluorescence analysis, micro-computed tomography, X-ray topography, detector calibration and reflectometry. Calculable undispersed radiation up to 200 keV will be available for radiometric applications.
The first hard x-ray beamline at BESSY II has been installed by BAM and PTB at a superconducting 7 T wavelength shifter. The main optical elements of the beamline are a double-multilayer monochromator and a double-crystal monochromator. Depending on the application, the two devices are used separately or in-line. The main applications of the monochromatic radiation with photon energies up to 60 keV are x-ray fluorescence analysis, micro computed tomography, x-ray topography, detector calibration and reflectometry. Calculable undispersed radiation up to 200 keV is available for radiometric applications.
Results are reported from a pilot study under the Consultative Committee for Amount of Substance (CCQM) to compare measurements of and resolve any relevant measurement issues in, the amount of thermal SiO2 oxide on (100) and (111) orientation Si wafer substrates in the thickness range 1.5 - 8 nm. As a result of the invitation to participate in this activity, 45 sets of measurements have been made in different laboratories using 10 analytical methods: medium-energy ion scattering spectrometry (MEIS), nuclear reaction analysis (NRA), RBS, elastic backscattering spectrometry (EBS), XPS, SIMS, ellipsometry, grazing-incidence x-ray reflectrometry (GIXRR), neutron reflectometry and transmission electron microscopy (TEM). The measurements are made on separate sets of 10 carefully prepared samples, all of which have been characterised by a combination of ellipsometry and XPS using carefully established reference conditions and reference parameters.
The results have been assessed against the National Physical Laboratory (NPL) data and all show excellent linearity. The remaining data sets correlate with the NPL data with average root-mean-square scatters of 0.15 nm, half being better than 0.1 nm and a few at or better than 0.05 nm. Each set of data allows a relative scaling constant and a zero thickness offset to be determined. Each method has an inherent zero thickness offset between 0 nm and 1 nm and it is these offsets, measured here for the first time, that have caused many problems in the past. There are three basic classes of offset: water and carbonadeous contamination equivalent to ~1 nm as seen by ellipsometry; adsorbed oxygen mainly from water at an equivalent thickness of 0.5 nm as seen by MEIS, NRA, RBS and possibly GIXRR; and no offset as seen by XPS using the Si 2p peaks. Each technique has a different uncertainty for the scaling constant and consistent results have been achieved. X-Ray photoelectron spectroscopy has large uncertainties for the scaling constant but a high precision and, critically, if used correctly, has zero offset. Thus, a combination of XPS and the other methods allows the XPS scaling constant to be determined with low uncertainty, traceable via the other methods. XPS laboratories returning results early were invited to test a new reference procedure. All showed very significant improvements. The reference attenuation lengths thus need scaling by 0.986 ± 0.009 (at an expansion factor of 2) deduced from the data for the other methods. Several other methods have small offsets and, to the extent that these can be shown to be constant or measurable, then these methods will also show low uncertainty. Recommendations are provided for parameters for XPS, MEIS, RBS and NRA to improve their accuracy.
Electron probe microanalysis (EPMA) measurement of thin-film thickness in the nanometre range
(2002)
The thickness of thin films of platinum and nickel on fused silica and silicon substrates has been determined by EPMA using the commercial software STRATAGEM for calculation of film thickness. Film thickness ranged in the order 10 nm. An attempt was made to estimate the confidence range of the method by comparison with results from other methods of analysis. The data show that in addition to the uncertainty of the spectral intensity measurement and the complicated fitting routine, systematic deviation caused by the underlying model should be added. The scattering in the results from other methods does not enable specification of a range of uncertainty, but deviations from the real thickness are estimated to be less than 20%.