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The certified reference material BAM-L200, a nanoscale stripe pattern for length calibration and specification of lateral resolution, is described. BAM-L200 is prepared from a cross-sectioned epitaxially grown layer stack of AlxGa1-xAs and InxGa1 xAs on a GaAs substrate. The surface of BAM-L200 provides a flat pattern with stripe widths ranging down to 1 nm. Calibration distances, grating periods and stripe widths have been certified by TEM with traceability to the length unit. The combination of gratings, isolated narrow stripes and sharp edges of wide stripes offers a plenty of options for the determination of lateral resolution, sharpness and calibration of length scale at selected settings of imaging surface analytical instruments. The feasibility of the reference material for an analysis of the lateral resolution is demonstrated in detail by evaluation of ToF-SIMS, AES and EDX images. Other applications developed in the community are summarized, too. BAM-L200 fully supports the implementation of the revised International Standard ISO 18516 (in preparation) which is based on knowledge outlined in the Technical Report ISO/TR 19319:2013.
Catalyst characterization
(2009)
A comprehensive characterization of plasma modified polymer surfaces or plasma-polymerized thin films needs access to parameters as
- concentration of saturated/unsaturated carbon species (e.g. aromaticity) or other double bonds as C=N or C=O,
- branching, and
- losses of crystallinty or other degrees of structural order.
Furthermore the complex ageing phenomena of plasma modified polymers/plasma-polymers and the measurement of an in-depth distribution of chemical species are challenges for the analyst. The talk will display selected examples where such challenges have been met by using advanced methods of surface chemical analyses as Photoelectron Spectroscopy with variable excitation energy (“SyncXPS”), X-ray Absorption Spectroscopy (NEXAFS) at C, N and O K-edges and Time-of-Flight Secondary Mass Spectroscopy (ToF-SIMS) combined with Principal Component analysis (PCA).
The certified reference material BAM-L200, a nanoscale stripe pattern for length calibration and specification of lateral resolution, is described. BAM-L200 is prepared from a cross-sectioned epitaxially grown layer stack of AlxGa1-xAs and InxGa1 xAs on a GaAs substrate. The surface of BAM-L200 provides a flat pattern with stripe widths ranging down to 1 nm. Calibration distances, grating periods and stripe widths have been certified by TEM with traceability to the length unit. The combination of gratings, isolated narrow stripes and sharp edges of wide stripes offers a plenty of options for the determination of lateral resolution, sharpness and calibration of length scale at selected settings of imaging surface analytical instruments. The feasibility of the reference material for an analysis of the lateral resolution is demonstrated in detail by evaluation of ToF-SIMS, AES and EDX images. Other applications developed in the community are summarized, too.
BAM-L200 fully supports the implementation of the revised International Standard ISO 18516 (in preparation) which is based on knowledge outlined in the Technical Report ISO/TR 19319:2013.
The certified reference material BAM-L200, a nanoscale stripe pattern for length calibration and specification of lateral resolution, is described. BAM-L200 is prepared from a cross-sectioned epitaxially grown layer stack of AlxGa1-xAs and InxGa1-xAs on a GaAs substrate. The surface of BAM-L200 provides a flat pattern with stripe widths ranging down to 1 nm. Calibration distances, grating periods and stripe widths have been certified by TEM with traceability to the length unit. The combination of gratings, isolated narrow stripes and sharp edges of wide stripes offers a plenty of options for the determination of lateral resolution, sharpness and calibration of length scale at selected settings of imaging surface analytical instruments. The feasibility of the reference material for an analysis of the lateral resolution is demonstrated in detail by evaluation of ToF-SIMS, AES and EDX images. Other applications developed in the community are summarized, too.
BAM-L200 fully supports the implementation of the revised International Standard ISO 18516 (in preparation) which is based on knowledge outlined in the Technical Report ISO/TR 19319:2013. Fundamental approaches to determination of lateral resolution and sharpness in beam-based methods
Measuring organic layers
(2016)
Many innovative products - from touchscreens to solar panels to pharmaceuticals – utilise multiple organic layers to create complex functionality. New techniques have been developed to remove and measure layers individually enabling improved product development and assisting with quality assurance. However, manufacturers cannot be certain of the depth of layer being removed and new reference materials for these techniques are needed to increase uptake, and remove a major barrier to innovation.
In this talk sample prep/handling, instrument calibration and data acquisition methods with examples from XPS, Auger and SIMS will be addressed in terms of their contributions to the reproducibility of data delivered by the methods.
Active parties in the field are VAMAS TWA 2 “Surface chemical analysis” (http://www.vamas.org/twa2/index.html), ISO/TC 201 “Surface chemical analysis” (https://www.iso.org/committee/54618.html) and the Surface Analysis Working Group (SAWG) at the International Meter Convention (https://www.bipm.org/en/ committees/cc/wg/sawg.html). The tools to improve the reproducibility of spectra, depth profiles and images at these international platforms are inter-laboratory comparisons, validated SOPs, standards and certified reference materials (CRM) as well as uncertainty budgets and establishment of traceability chains. The last point is of specific importance because all the methods, XPS, Auger and SIMS, are not primary methods.
To address quantitative XPS, AES and SIMS results of relevant inter-laboratory comparisons organized by SAWG considering measurands as alloy surface composition and thickness of thin films will be introduced. These comparisons delivered results which are viewed to be benchmarking, some of them resulted in ISO/TC 201 standards. For quantitative XPS and AES the principal outline of an uncertainty budget will be discussed together with the audience. Another issue of quantitative XPS which definitely needs consideration are valid methods for a determination of the transmission function of the instruments and even for the emission angle in the respective experiments.
Concerning the field of depth profiling it has to be investigated together with the audience whether the ISO (or ASTM) standards we have are sufficient to guarantee comparable results. Having in mind the number of different sputter ion species available today and range of samples of interest (metals, semiconductors, organic films) this might be questionable. And, how do depth profiling by AR-XPS and variable excitation energy XPS compete here?
For imaging surface chemical analysis, the characterization of the imaging system is an issue to be investigated. Here the determination of lateral resolution is a relevant topic.
Finally, the future needs to develop metrology for new applications e.g., ambient-pressure XPS, bio samples, and core-shell nanoparticles, will be issues raised for a discussion with the audience.
Lateral resolution of secondary ion mass spectrometry - results of an inter-laboratory comparison
(2007)
Recently, BAM organised an inter-laboratory comparison focussed on lateral resolution and accuracy of sub-micron length measurements by secondary ion mass spectrometry (SIMS). Results were submitted by 16 laboratories from 10 countries. The task was to analyse a cross-sectioned semiconductor multilayer stack. The resulting strip pattern in the surface of the sample shows narrow strips, step transitions and gratings of different periods. Imaging analysis of this pattern enables the determination of relevant parameters related to the lateral resolution: (i) The width (FWHM) of the primary ion beam, (ii) the distance between 16% and 84% intensity points in a profile across the image of a step transition and (iii) the modulation of intensity in the images of gratings with different periods. The parameter's data reported by the participants vary in a wide range. A strong variation in the data of primary ion beam width was observed for results measured with the same type of instrument. The distance between two narrow strips was measured with high accuracy. Twelve of sixteen of the submitted values are within the limits of uncertainty of the reference value 964 ± 35 nm. This result shows that the calibration of the length scale of the SIMS instruments is already rather precise in most of the participating laboratories.