In:
ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2020-01, No. 15 ( 2020-05-01), p. 1050-1050
Abstract:
The quality of interfaces between dielectrics and semiconductors has a tremendous impact on the performances of semiconductor devices. High-k dielectrics are omnipresent in the gate stack of advanced MOSFETs. They are also used as passivation layers for silicon in fields such as solar cells [ 1 ] or image sensors [ 2 ]. When referring to passivation, two mechanisms can be identified: chemical passivation (quantified by the interface state density, D it ) and electric-field passivation (quantified by fixed oxide charge density, Q ox ). An ideal characterization method for passivated silicon should give access to both chemical and field-effect relevant quantities (ideally being able to distinguish them) in a non-destructive way. Among the commonly used techniques, we can cite electrical methods based on current or capacitance monitoring of simple test devices [ 3 ], Corona characterization of semiconductors [ 4 ], carrier lifetime extraction [ 5 ] conducted through photoconductance or photoluminescence decay measurements, etc. The choice among these several options is based on criteria such as sensitivity, non-destructiveness, possibility of direct on-wafer probing without any additional device fabrication steps, ability to discriminate D it and Q ox , capability to provide a high spatial resolution. A recent technique which could meet all these criteria is the second harmonic generation (SHG) [ 6 ], provided that an appropriate calibration method is developed for D it and Q ox extraction. The SHG is a non-linear optics phenomenon: when a high intensity laser beam of wavelength λ reaches a sample, a second harmonic wave at λ/2 is generated by the sample. For centrosymmetric materials (such as silicon, SiO 2 , Al 2 O 3 , etc.) the SHG signal contains two parts: one related to the symmetry breaking inherently present at interfaces between two different materials, and another one produced by any “static” electric field in the sample [ 7 ]. Such field is present at the vicinity of dielectric-to-semiconductor interfaces due to charge trapping by various mechanisms. In other words, the magnitude of the generated SHG signal contains information on both D it and Q ox This technique has already been used for dielectric characterization with various modalities (SHG versus power, time, wavelength ...) [ 8 ], [ 9 ], [ 10 ]. The SHG proved very promising (sensitive, non-destructive, applied directly on-wafer, etc.); however its extensive use still needs a more general calibration methodology. Such a methodology requires not only SHG measurements, but also real Q ox /D it values extracted by classical electrical methods on the same samples and modeling to understand/anticipate the expected effect of these parameters on the SHG signal. In this paper, we’ll discuss all these issues based on a review of our recent advances on how to exploit SHG for dielectrics on semiconductor characterization. Acknowledgements This work was supported by Region Rhône Alpes (ARC6 program), the French National Research Agency within the framework of the OXYGENE project (ANR-17-CE05-0034) and French National Plan Nano2022, within the IPCEI Nanoelectronics for Europe program. [1] A. G. Aberle, "Surface passivation of crystalline silicon solar cells: a review," Progress in Photovoltaics: Research and Applications, vol. 8, pp. 473-487, 2000. [2] J. L. Regolini, D. Benoit, and P. Morin, "Passivation issues in active pixel CMOS image sensors," Microelectronics Reliability, vol. 47, pp. 739-742, 2007. [3] D. K. Schroder, Semiconductor Material and Device Chracterization , 3rd Edition ed. New Jersey: John Wiley & sons, 2006. [4] M. Wilson, J. Lagowski, L. Jastrzebski, A. Savtchouk, and V. Faifer, "COCOS (corona oxide characterization of semiconductor) non-contact metrology for gate dielectrics," AIP Conference Proceedings, vol. 550, pp. 220-225, 2001. [5] D. K. Schroder, "Carrier lifetimes in silicon," Electron Devices, IEEE Transactions on, vol. 44, pp. 160-170, 1997. [6] G. Lupke, "Characterization of semiconductor interfaces by second-harmonic generation," Surface Science Reports, vol. 35, pp. 75-161, 1999. [7] J. E. Sipe, D. J. Moss, and H. M. van Driel, "Phenomenological theory of optical second- and third-harmonic generation from cubic centrosymmetric crystals," Physical Review B, vol. 35, pp. 1129-1141, 1987. [8] J. Price, M. Lei, P. S. Lysaght, G. Bersuker, and M. C. Downer, "Charge trapping defects in Si/SiO2/Hf(1−x)SixO2 film stacks characterized by spectroscopic second-harmonic generation," Journal of Vacuum Science & Technology B, vol. 29, p. 04D101, 2011. [9] N. M. Terlinden, G. Dingemans, V. Vandalon, R. H. E. C. Bosch, and W. M. M. Kessels, "Influence of the SiO2 interlayer thickness on the density and polarity of charges in Si/SiO2/Al2O3 stacks as studied by optical second-harmonic generation," Journal of Applied Physics, vol. 115, p. 033708, 2014. [10] H. Park, J. Qi, Y. Xu, K. Varga, S. M. Weiss, B. R. Rogers , et al. , "Boron induced charge traps near the interface of Si/SiO2 probed by second harmonic generation," Physica Status Solidi (b), vol. 247, pp. 1997-2001, 2010.
Type of Medium:
Online Resource
ISSN:
2151-2043
DOI:
10.1149/MA2020-01151050mtgabs
Language:
Unknown
Publisher:
The Electrochemical Society
Publication Date:
2020
detail.hit.zdb_id:
2438749-6
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