AVS 59th Annual International Symposium and Exhibition
    Applied Surface Science Thursday Sessions
       Session AS-ThM

Paper AS-ThM4
New Organic Reference Materials for Cluster Ion Sputter Depth Profiling

Thursday, November 1, 2012, 9:00 am, Room 20

Session: Applications of Large Cluster Ion Beams
Presenter: A.G. Shard, National Physical Laboratory, UK
Authors: A.G. Shard, National Physical Laboratory, UK
S. Spencer, National Physical Laboratory, UK
S. Smith, National Physical Laboratory, UK
I.S. Gilmore, National Physical Laboratory, UK
R. Havelund, National Physical Laboratory, UK
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Over the past three years, the availability of multilayered organic reference materials has enabled rapid progress in cluster ion beam sputtering for organic depth profiling. These materials have provided manufacturers and practitioners with a common benchmark against which the performance of different experimental methods can be judged. Furthermore, such reference materials are invaluable in providing experimental evidence against which theory can be tested. Reference materials based on Irganox 1010 and Irganox 3114 [1] have been extensively used in this regard [2,3,4]. Results from a VAMAS interlaboratory study, completed in 2011, using argon cluster ion beams as the sputtering source are briefly presented to demonstrate the relevance and utility of these reference materials. These sources demonstrate a remarkable repeatability of better than 1% relative standard deviation in sputtering yield. Depth resolutions close to 5 nm at low impact energies can be acheived. The materials also demonstrate that electrons used for charge compensation can cause very significant molecular damage which affects profiles to a significant depth, often over many tens of nanometers.Whilst this reference material has been extremely valuable, it is not suitable for the full range of analytical methods used in conjunction with cluster ion beam sputtering and may not be representative of all molecular species of analytical interest. As examples, the Irganox 1010 and Irganox 3114 are difficult to distinguish using either XPS or positive SIMS analysis. Alternatives are being studied, such as those materials which are of great commercial importance to the organic electronic industry, e.g. aluminium tris(hydroxyquinolate). In this work, we describe the development of new reference materials including amino acids, fluorinated compounds, specifically for XPS analysis, and compounds used in organic displays. The precision and accuracy of the layer thicknesses and the stability of the materials will be described along with their performance in cluster ion sputter depth profiling experiments. Additionally, research into a new class of reference material based upon binary mixtures of organic compounds with known compositions will be described.[1] A. G. Shard, F. M. Green, P. J. Brewer, M. P. Seah and I. S. Gilmore, J. Phys. Chem. B 2008; 112: 2596.[2] A. G. Shard, R. Foster, I. S. Gilmore, J. L. S. Lee, S. Ray and L. Yang, Surf. Interface Anal. 2011; 43: 510.[3] P. Sjovall, D. Rading, S. Ray, L. Yang, and A. G. Shard, J. Phys. Chem. B 2010; 114: 769.[4] D. Mao, A. Wucher, and N. Winograd, Anal. Chem. 2010; 82: 57.