Conférencier: David N. Siedman, Northwestern University, Department of Materials Science and Engineering and Northwestern University Center for Atom-Probe Tomography (NUCAPT), Illinois, USA

Atom-probe tomography (APT) is finally coming of age, after a long gestation period, because of the availability of reliable and well-engineered commercial instruments and data analysis software, which are both robust and ergonomic. Atom-probe tomography is currently being applied to an ever-widening range of materials classes that involve important scientific and technological problems in materials science and engineering. For example, atom-probe tomography is being utilized to study specific problems concerning metallic structural materials, thin films and multilayers, semiconductor nanowires, metal oxides, organic/inorganic interfaces, and organic and biological materials. Dual-beam focused-ion beam (FIB) microscopy and its application to the fabrication of atom-probe tomography microtip specimens has dramatically improved our ability to prepare microtips of different configurations, for example, preparing specimens from planar geometries. To amplify on the above points I will discuss the topic of silicidation in reasonable detail. Atom-probe tomography was utilized to study the distribution of platinum after silicidation of a solid-solution Ni0.95Pt0.05 thin-film on Si (100). Direct evidence of platinum short-circuit diffusion via grain boundaries, Harrison regime-B, is found after silicidation to form (Ni0.99Pt0.01)Si. This underscores the importance of interfacial phenomena for stabilizing this low-resistivity phase, providing insights into the modification of NiSi texture, grain size, and morphology caused by platinum. Platinum segregates at the (Ni0.99Pt0.01)Si/Si(100) interface, which may be responsible for the increased resistance of (Ni0.99Pt0.01)Si to agglomeration. For this study specimens were prepared from planar structures using a dual-beam FIB microscope and without this instrument it would have been impossible to fabricate microtip specimens for atom-probe tomography.