Medium energy ion scattering for the high depth resolution characterisation of high-k dielectric layers of nanometer thickness

► The essence of medium energy ion scattering (MEIS) for nanolayer analysis is given. ► MEIS is applied to characterise high-k nanolayers and (DRAM) multilayer structures. ► MEIS is shown to give quantitative composition depth profiles and layer thicknesses. ► MEIS is shown to identify the nature &a...

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Bibliographic Details
Published in:	Applied surface science Vol. 281; pp. 8 - 16
Main Authors:	van den Berg, J.A., Reading, M.A., Bailey, P., Noakes, T.Q.C., Adelmann, C., Popovici, M., Tielens, H., Conard, T., de Gendt, S., van Elshocht, S.
Format:	Journal Article Conference Proceeding
Language:	English
Published:	Amsterdam Elsevier B.V 15-09-2013 Elsevier
Subjects:	Condensed matter: electronic structure, electrical, magnetic, and optical properties Condensed matter: structure, mechanical and thermal properties Cross-disciplinary physics: materials science; rheology Exact sciences and technology High resolution depth profiling High-k nanolayers Medium energy ion scattering analysis Metal–insulator–metal capacitor (MIMcap) layers Physics Medium energy ion scattering analysis High-k nanolayers Metal–insulator–metal capacitor (MIMcap) layers High resolution depth profiling Ion scattering analysis Thickness Depth resolution Capacitors Metal―insulator―metal capacitor (MIMcap) layers Ion scattering
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Summary:	► The essence of medium energy ion scattering (MEIS) for nanolayer analysis is given. ► MEIS is applied to characterise high-k nanolayers and (DRAM) multilayer structures. ► MEIS is shown to give quantitative composition depth profiles and layer thicknesses. ► MEIS is shown to identify the nature & extent of layer intermixing and segregation. Medium energy ion scattering (MEIS) using, typically, 100–200keV H+ or He+ ions derives it ability to characterise nanolayers from the fact that the energy after backscattering depends (i) on the elastic energy loss suffered in a single collision with a target atom and (ii) on the inelastic energy losses on its incoming and outgoing trajectories. From the former the mass of the atom can be determined and from the latter its depth. Thus MEIS yields depth dependent compositional and structural information, with high depth resolution (sub-nm near the surface) and good sensitivity for all but the lighter masses. It is particularly well suited for the depth analysis of high-k multilayers of nanometer thickness. Accurate quantification of the depth distributions of atomic species can be obtained using suitable spectrum simulation. In the present paper, important aspects of MEIS including quantification, depth resolution and spectrum simulation are briefly discussed. The capabilities of the technique in terms of the high depth resolution layer compositional and structural information it yields, is illustrated with reference to the detailed characterisation of a range of high-k nanolayer and multilayer structures for current microelectronic devices or those still under development: (i) HfO2 and HfSiOx for gate dielectric applications, including a TiN/Al2O3/HfO2/SiO2/Si structure, (ii) TiN/SrTiO3/TiN and (iii) TiO2/Ru/TiN multilayer structures for metal–insulator–metal capacitors (MIMcaps) in DRAM applications. The unique information provided by the technique is highlighted by its clear capability to accurately quantify the composition profiles and thickness of nanolayers and complex multilayers as grown, and to identify the nature and extent of atom redistribution (e.g. intermixing, segregation) during layer deposition, annealing and plasma processing. The ability makes it a valuable tool in the development of the nanostructures that will become increasingly important as device dimensions continue to be scaled down.
ISSN:	0169-4332 1873-5584
DOI:	10.1016/j.apsusc.2013.02.003