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SIMS21, Poland 2017 - Alexis Franquet abstract

Alexis Franquet oral presentation (PB3-Fri2-1-1)

Self Focusing SIMS: a new metrology for the analysis of confined volumes

Alexis Franquet1, Bastien Douhard1, Richard J.H. Morris1, Valentina Spampinato1, Thierry Conard1, Wilfried Vandervorst1,2

1 imec, Kapeldreef 75, 3001 Leuven, Belgium
2 Instituut voor Kern- en Stralingsfysics, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium


An important growth driver for the semiconductor industry is the shrinking of transistor dimensions to increase the overall performance and functionality. To retain device performance at very small dimensions, additional improvements are required and include the implementation of new materials (high-k’s, metal gate, III-V or group IV alloys) and the introduction of new 3D device architectures, e.g. FinFET’s.

In this context, the metrology needs (such as determination of the exact composition, doping concentration, etc.) are more and more shifting from the analysis of blanket samples to more real devices where thin films are grown in very confined volumes (with dimensions ≤ 20nm). Such metrology step makes the standard analysis methods like XPS, SIMS and RBS no longer applicable due to a lack of spatial resolution. However, Self Focusing SIMS (SF-SIMS) overcomes the spatial resolution limitations of SIMS without sacrificing the sensitivity [1]. The concept behind SF-SIMS is based on determining the composition of a specific compound using the cluster ions which contain the constituents of the compound. Their formation mechanism implies that all cluster constituents originate from the same collision cascade and were in close proximity (< 0.5nm) within the starting sample. As such, the composition information becomes confined (i.e. self focused) to the areas where all constituents are simultaneously present.

In this work, the SF-SIMS approach is applied to a large variety of geometrical structures, i.e. squares, trenches, ... of different lateral dimensions (down to 20nm) and various types of materials, e.g. Ge, SiGe, InGaAs, InAlAs, GaN, .... Emphasis will be given to the determination of the compound composition, doping levels, mixed phase analysis, ... The presented results will also focus on the analysis of possible substrate diffusion within narrow trenches using the SF-SIMS concept and to the use of a combined ToF-SIMS/in-situ SPM tool for the study of topography development during profiling. Moreover, possible difficulties and/or limiting factors in SF-SIMS profiling, e.g. presence/absence of ion redeposition from surrounding areas, decay length, .., will be discussed. The obtained results will be compared to analyses performed with other complementary methods such as AES, TEM, Atom Probe Tomography, ....

Acknowledgments: This project has received funding both from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 688225 and from the Electronic Component Systems for European Leadership Joint Undertaking under grant agreement No 692527. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and Netherlands, Belgium, France, Hungary,Ireland, Denmark, Israel”.

[1] A. Franquet, B. Douhard, D. Melkonyan, P. Favia, T. Conard, W. Vandervorst, Applied Surface Science 365, 2016, 143–152.