Materials science depth profiling

MEIS has proven to be a powerful and intuitive tool for the study of the composition and geometrical structure of surfaces and interfaces several layers below a surface. The fact that the technique is truly quantitative is all but unique in surface science. The use of very high resolution depth profiling, made possible by the high-resolution energy detectors in MEIS, will find increased applicability in many areas of materials science. With continued technical development, resulting in less costly instrumentation, the technique should become of even wider importance in the years to come. 

Secondary ion mass spectrometry (SIMS) is a widespread analytical technique for the study of surfaces in materials science. Mostly used for elemental analyses and depth profiling, it is particularly relevant for many different fields of research including cultural heritage studies. Reviews of its use for the study of ancient glasses or metal artefacts already exist in the literature [Spoto 2000, Darque-Ceretti and Aucouturier 2004, Dowsett and Adriaens 2004, Adriens and Dowsett 2006, Anderle et al. 2006, McPhail 2006], but as only elemental information is obtained, these studies are limited to inorganic materials. 

SIMS and SNMS are versatile analytical techniques for the compositional characterization of solid surfaces and interfaces in materials research.92-94 As one of the most important applications, both surface analytical techniques allow depth profile analysis (concentration profile as a function of the depth analyzed) to be performed in materials science and the semiconductor industry with excellent depth resolution in the low nm range. For depth profiling in materials science, dynamic SIMS and SNMS using high primary ion beam doses are applied. Both techniques permit the analysis of light elements such as H, , C and N, which are difficult to measure with other analytical techniques. 

Imaging MS is and will become increasingly critical for many aspects of materials science. One example is in the semiconductor industry, where the ability to provide spatial and chemical information on the length scales of current integrated circuit fabrication (50 nm or better) with depth profiling to provide layer-by-layer maps of the fabricated layers is critical for the continued advancement of the computer industry. Maps of any heterogeneous surface are important in other areas of materials science. For example, using various laser desorption techniques, information about the molecules found in specific inclusions in meteorites or defects in reactive surfaces can be obtained. 

B.V. King. Sputter Depth Profiling. In D.J. O Conner, B.A. Sexton, and R. St. C. Smart, editors. Surface Analysis Methods in Materials Science. Springer Series in Surface Sciences, Volume 23. Springer-Verlag, Berlin, 1992. 

A wide range of other nuclear reactions have been used in material science for the depth-profiling analysis of a number of different elements, some of which are tabulated by Feldman and Mayer (1986). Whether these techniques will in the future prove useful for polymers remains to be seen. 

Materials science (microelectronics analysis, surface layers, multilayers, PIXE channeling of dopants in crystals, depth profiling, binary alloys, impurities deposited in nuclear fusion devices, magnetic relaxation in nanocrystalline iron, insulating materials, radiation-induced segregation, superconductors, catalysts, and diffusion studies). 

FIGURE 40.21 Comparison of the depth profiles of a copper impurity by trace element accelerator mass spectrometry (TEAMS) and secondary ion mass spectrometry (SIMS). Reprinted from McDaniel, ED, Datar, S.A., Nigam, M., Ravi Prasad, G.V. (2002) Impurity measurements in semiconductor materials using trace element accelerator mass spectrometry. Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms, 190 1-A), 826-830. Copyright (2002), with permission from Elsevier Science. 

Toujou, E, Yoshikawa, S., Homma, Y., Takano, A., Takenaka, H.,Tomita, M., Li, Z., Hasegawa,T., Sasakawa, K., Schuhmacher, M., Merkulov, A., Kim, H.K., Moon, D.W, Hong, T, Won, X (2004) Evaluation of BN-delta-doped multilayer reference materials for shallow depth profiling in SIMS round-robin test. Applied Surface Science, 231-232,649-652. 

The authors have a complementary cross-disciplinary expertise in material science, MS technology, ionization mechanisms, and instrumentation development. Most of the authors were partners of the EMDPA project, an acronym for Elemental and Molecular Depth Profiling Analysis by pulsed radiofrequency (RF) glow discharge time-of-flight mass spectroscopy (GD-TOFMS) within the European Union (EU) FP6 work program [5]. 

Interface Science. The interface of two materials can be probed using several techniques, including some of the techniques used for surface analysis. Depth profiling is a method by which information is gained from within the sample. If the interface in... 

F. (Frangois) Renters received a Ph.D. in chemistry from the University of Brussels in Belgium in 1991. Since then he has worked at. or been connected with. Vrije Univer-siteit Brussel, University of Guelph in Canada, and the Materials Science Depariincni of the Lawrence Livermore National Laboratory in Berkeley, California. He has recently-joined the Chemistry Department at the Universile Libre de Bruxelles in Belgium. His principal interests have been in the development of methodologies for depth profiling with AES and other surface specific techniques. 

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