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Toward Site-Specific Dopant Contrast in Scanning Electron Microscopy

Published online by Cambridge University Press:  20 May 2014

Zdena Druckmüllerová ,
Miroslav Kolíbal ,
Tomáš Vystavěl  and
Tomáš Šikola
Zdena Druckmüllerová
Affiliation:
Institute of Physical Engineering, Brno University of Technology, Technická 2, 61669 Brno, Czech Republic CEITEC BUT, Brno University of Technology, Technická 10, 61669 Brno, Czech Republic
Miroslav Kolíbal*
Affiliation:
Institute of Physical Engineering, Brno University of Technology, Technická 2, 61669 Brno, Czech Republic CEITEC BUT, Brno University of Technology, Technická 10, 61669 Brno, Czech Republic
Tomáš Vystavěl
Affiliation:
FEI Company, Podnikatelská 6, 61200 Brno, Czech Republic
Tomáš Šikola
Affiliation:
Institute of Physical Engineering, Brno University of Technology, Technická 2, 61669 Brno, Czech Republic CEITEC BUT, Brno University of Technology, Technická 10, 61669 Brno, Czech Republic
*
*Corresponding author. [email protected]
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Abstract

Since semiconductor devices are being scaled down to dimensions of several nanometers there is a growing need for techniques capable of quantitative analysis of dopant concentrations at the nanometer scale in all three dimensions. Imaging dopant contrast by scanning electron microscopy (SEM) is a very promising method, but many unresolved issues hinder its routine application for device analysis, especially in cases of buried layers where site-specific sample preparation is challenging. Here, we report on optimization of site-specific sample preparation by the focused Ga ion beam (FIB) technique that provides improved dopant contrast in SEM. Similar to FIB lamella preparation for transmission electron microscopy, a polishing sequence with decreasing ion energy is necessary to minimize the thickness of the electronically dead layer. We have achieved contrast values comparable to the cleaved sample, being able to detect dopant concentrations down to 1×1016 cm−3. A theoretical model shows that the electronically dead layer corresponds to an amorphized Si layer formed during ion beam polishing. Our results also demonstrate that contamination issues are significantly suppressed for FIB-treated samples compared with cleaved ones.

Keywords

dopant mappingscanning electron microscopy (SEM)focused ion beam (FIB)amorphizationsemiconductors and semiconductor devices
Type
Techniques and Instrumentation Development
Information
Microscopy and Microanalysis , Volume 20 , Issue 4 , August 2014 , pp. 1312 - 1317
Copyright
© Microscopy Society of America 2014 

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References

Cazaux, J. (2010). Material contrast in SEM: Fermi energy and work function effects. Ultramicroscopy 110, 242–253.CrossRefGoogle ScholarPubMed
Čechal, J., Tomanec, O., Škoda, D., Koňáková, K., Hrnčíř, T., Mach, J., Kolíbal, M. & Šikola, T. (2009). Selective growth of Co islands on ion beam induced nucleation centers in a native SiO2 film. J Appl Phys 105, 084314.CrossRefGoogle Scholar
Chakk, Y. & Horvitz, D. (2006). Contribution of dynamic charging effects into dopant contrast mechanisms in silicon. J Mat Sci 41, 4554–4560.CrossRefGoogle Scholar
Chang, T.H.P. & Nixon, W.C. (1967). Electron beam induced potential contrast on unbiased planar transistors. Solid-State Electron 10, 701–702.CrossRefGoogle Scholar
Chee, A.K.W., Beanland, R., Midgley, P.A. & Humpreys, C.J. (2010). Site-selective dopant profiling of p-n junction specimens in the dual-beam FIB/SEM system. J Phys Conf Ser 209, 012069.CrossRefGoogle Scholar
Chee, A.K.W., Broom, R.F., Humphreys, C.J. & Bosch, E.G.T. (2011). A quantitative model for doping contrast in the scanning electron microscope using calculated potential distributions and Monte Carlo simulations. J Appl Phys 109, 013109.CrossRefGoogle Scholar
Cooper, D., Ailliot, C., Barnes, J.-P., Hartmann, J.-M., Salles, P., Benassayag, G. & Dunin-Borkowski, R.E. (2010). Dopant profiling of focused ion beam milled semiconductors using off-axis electron holography; reducing artifacts, extending detection limits and reducing the effects of gallium implantation. Ultramicroscopy 110, 383–389.CrossRefGoogle Scholar
Cooper, D., Hartmann, J.-M. & Gambacorti, N. (2011). Low energy Xe milling for the quantitative profiling of active dopants by off-axis electron holography. J Appl Phys 110, 044511.CrossRefGoogle Scholar
Cooper, D., Rivallin, P., Hartmann, J.-M., Chabli, A. & Dunin-Borkowski, R.E. (2009). Extending the detection limit of dopants for focused ion beam prepared semiconductor specimens examined by off-axis electron holography. J Appl Phys 106, 064506.CrossRefGoogle Scholar
Dapor, M., Jepson, M.A.E., Inkson, B.J. & Rodenburg, C. (2009). The effect of oxide overlayers on secondary electron dopant mapping. Microsc Microanal 15, 237–243.CrossRefGoogle ScholarPubMed
El-Gomati, M., Zaggout, F., Jayacody, H., Tear, S. & Wilson, K. (2005). Why is it possible to detect doped regions of semiconductors in low voltage SEM. Surf Interface Anal 37, 901–911.CrossRefGoogle Scholar
El-Gomati, M.M. & Wells, T.C.R. (2011). Very-low-energy electron microscopy of doped semiconductors. Appl Phys Lett 79, 2931–2933.CrossRefGoogle Scholar
Giannuzzi, L.A., Geurts, R. & Ringnalda, J. (2005). 2kV Ga+ FIB milling for reducing amorphous damage in silicon. Microsc Microanal 11(Suppl 2), 828–829.CrossRefGoogle Scholar
Heath, J.T., Jiang, C.-S. & Al-Jassim, M.M. (2012). Measurement of semiconductor surface potential using the scanning electron microscope. J Appl Phys 111, 046103.CrossRefGoogle Scholar
Jepson, M.A.E., Inkson, B.J., Beanland, R., Chee, A.K.W., Humpreys, C.J. & Rodenburg, C. (2010). Progress towards site-specific dopant profiling in the scanning electron microscope. J Phys Conf Ser 209, 012068.CrossRefGoogle Scholar
Jepson, M.A.E., Liu, X., Bell, D., Ferranti, D., Inkson, B. & Rodenburg, C. (2011). Resolution limits of secondary electron dopant contrast in helium ion and scanning electron microscopy. Microsc Microanal 17, 637–642.CrossRefGoogle ScholarPubMed
Katano, Y., Doi, T., Ohno, H. & Yoh, K. (2002). Surface potential analysis on doping superlattice by electrostatic force microscope. Appl Surf Sci 188, 399–402.CrossRefGoogle Scholar
Kato, N.I., Kohno, Y. & Saka, H. (1999). Side-wall damage in a transmission electron microscopy specimen of crystalline Si prepared by focused ion beam etching. J Vac Sci Technol A 17, 1201–1204.CrossRefGoogle Scholar
Kazemian, P., Mentink, S.A.M., Rodenburg, C. & Humphreys, C.J. (2006a). High resolution quantitative two-dimensional dopant mapping using energy-filtered secondary electron imaging. J Appl Phys 100, 054901.CrossRefGoogle Scholar
Kazemian, P., Mentink, S.A.M., Rodenburg, C. & Humphreys, C.J. (2007). Quantitative secondary electron energy filtering in a scanning electron microscope and its applications. Ultramicroscopy 107, 140–150.CrossRefGoogle Scholar
Kazemian, P., Twitchett, A.C., Humphreys, J.C. & Rodenburg., C. (2006b). Site-specific dopant profiling in a scanning electron microscope using focused ion beam prepared specimens. Appl Phys Lett 88, 212110.CrossRefGoogle Scholar
Kieft, E. & Bosch, E. (2008). Refinement of Monte Carlo simulations of electron-specimen interaction in low-voltage SEM. J Phys D Appl Phys 41, 215310.CrossRefGoogle Scholar
Kolíbal, M., Čechal, J., Bartošík, M., Mach, J. & Šikola, T. (2010). Stability of hydrogen-terminated vicinal Si(1 1 1) surface under ambient atmosphere. Appl Surf Sci 256, 3423–3426.CrossRefGoogle Scholar
Kolíbal, M., Matlocha, T., Vystavěl, T. & Šikola, T. (2011). Low energy focused ion beam milling of silicon and germanium nanostructures. Nanotechnology 22, 105304.CrossRefGoogle ScholarPubMed
Mayer, J., Giannuzzi, L.A., Kamino, T. & Michael, J. (2007). TEM sample preparation and FIB-induced damage. MRS Bull 32, 400–407.CrossRefGoogle Scholar
Menzel, R., Gärtner, K., Wesch, W. & Hobert, H. (2000). Damage production in semiconductor materials by a focused Ga+ ion beam. J Appl Phys 88, 5658–5661.CrossRefGoogle Scholar
Mika, F. & Frank, L. (2008). Two-dimensional dopant profiling with low-energy SEM. J Microsc 230, 76–83.CrossRefGoogle ScholarPubMed
Perovic, D.D., Castell, M.R., Howie, A., Lavoie, C., Tiedje, T. & Cole, J.S.W. (1995). Field-emission SEM imaging of compositional and doping layer semiconductor superlattices. Ultramicroscopy 58, 104–113.CrossRefGoogle Scholar
Rodenburg, C., Jepson, M.A.E., Bosch, E.G.T. & Dapor, M. (2010). Energy selective scanning electron microscopy to reduce the effect of contamination layers on scanning electron microscope dopant mapping. Ultramicroscopy 110, 1185–1191.CrossRefGoogle ScholarPubMed
Rodenburg, C., Jepson, M.A.E., Inkson, B.J., Beanland, R., Chee, A.K.W. & Humphreys, C.J. (2010). Energy filtered scanning electron microscopy: Applications to dopant contrast. J Phys Conf Ser 209, 012053.CrossRefGoogle Scholar
Quadbeck, P., Ebert, P., Urban, K., Gebauer, J. & Krause-Rehberg, R. (2000). Effect of dopant atoms on the roughness of III-V semiconductor cleavage surfaces. Appl Phys Lett 76, 300–302.CrossRefGoogle Scholar
Sealy, C.P., Castell, M.R. & Wilshaw, P.R. (2000). Mechanism for secondary electron dopant contrast in the SEM. J Electron Microsc 49, 311–321.CrossRefGoogle ScholarPubMed
Sze, S.M. & Kwok, K.N.G. (2007). Physics of Semiconductor Devices . Hoboken, New Jersey: John Wiley & Sons.Google Scholar
Utke, I., Hoffmann, P. & MeIngailis, J. (2008). Gas-assisted focused electron beam and ion beam processing and fabrication. J Vac Sci Technol B 26, 1197–1276.CrossRefGoogle Scholar
Venables, D., Jain, H. & Collins, D.C. (1998). Secondary electron imaging as a two-dimensional dopant profiling technique: Review and update. J Vac Sci Technol B 16, 362–366.CrossRefGoogle Scholar
Volotsenko, I., Molotskii, M., Barkay, Z., Marczewski, J., Grabiec, P., Jaroszewicz, B., Meshulam, G., Grunbaum, E. & Rosenwaks, Y. (2010). Secondary electron doping contrast: Theory based on scanning electron microscope and Kelvin probe force microscopy measurements. J Appl Phys 107, 014510.CrossRefGoogle Scholar
Walker, C.G.H., Zaggout, F. & El-Gomati, M.M. (2008). The role of oxygen in secondary electron contrast in doped semiconductors using low voltage scanning electron microscopy. J Appl Phys 104, 123713.CrossRefGoogle Scholar
Ziegler, J.F., Ziegler, M.D. & Biersack, J.P. (2010). SRIM—The stopping and range of ions in matter (2010). Nucl Instrum Meth Phys Res B 268, 1818–1823.CrossRefGoogle Scholar