Silicon Carbide and Related Materials 2009

Paper Title Page

Authors: Thomas L. Straubinger, Erwin Schmitt, S. Storm, Michael Vogel, Arnd Dietrich Weber, Andreas Wohlfart
Abstract: One of the most crucial defects for the device fabrication on silicon carbide (SiC) substrates are areas with low crystalline quality and micro-pipe clusters which can still occupy several percent of the area in commercial available 4H-substrates. These defects originate from the seed or are generated by modification changes during growth and can be easily detected under crossed polarizers. In this presentation the historic development at SiCrystal from Acheson material to wafers with 100mm diameter, state of the art micro-pipe density and excellent crystalline quality (FWHM < 20 arcsec) on whole area will be shown. Additionally the influence of carbon inclusions on surface quality and the present dislocation densities in 4H substrates will be discussed. While carbon inclusions were reduced to uncritical levels dislocation densities are still in the range of 104 cm-2. Therefore strategies for further reduction will be pointed out. Finally a resistivity limit (16 mΩcm) for stacking fault formation during annealing at 1150°C will be defined.
Authors: Masashi Nakabayashi, Tatsuo Fujimoto, Masakazu Katsuno, Hiroshi Tsuge, Takashi Aigo, S. Satoh, Hirokatsu Yashiro, Taizo Hoshino, Hosei Hirano, Wataru Ohashi
Abstract: In-grown type stacking faults (SFs) like structures were observed in 100mm diameter 4H-SiC crystals by Photoluminescence (PL) mappings, and structural analyses using HRTEM clarified that the SF-like structures were comprised of 6H (3, 3) stacking sequences. The stacking sequences of the SF-like structures observed are different from the SFs formed in the a-face grown crystals, suggesting that it is due to 6H nucleation on {0001} plane terraces.
Authors: Katsunori Danno, Hiroaki Saitoh, Akinori Seki, H. Daikoku, Y. Fujiwara, T. Ishii, H. Sakamoto, Yoichiro Kawai
Abstract: High-speed solution growth using Si-Cr based melt has been performed on on-axis 4H-SiC(0001) at a high temperature of about 2000°C. The maximum growth rate for one-hour growth reaches to 1120 m/h, while the typical growth rate of growth for 2h is about 500 m/h. A large crystal that is about 25 mm in diameter and 1650 m in thickness can be obtained by growth for 5h. The crystal quality is confirmed to be homogeneous by X-ray diffraction and X-ray topography, because FWHM is less than 30 arcsec. Etch pit density of the threading dislocations in the grown crystal is 103-104 cm-2, and that of basal plane dislocation is 2×102-3×103 cm-2. Resistivity of the crystals grown by the solution growth is comparable to those of crystals grown by physical vapor transport technique.
Authors: Emil Tymicki, Krzysztof Grasza, Katarzyna Racka, Marcin Raczkiewicz, Tadeusz Łukasiewicz, Maciej Gała, Kinga Kościewicz, Ryszard Diduszko, Rafał Bożek
Abstract: In this work we present the growth of 4H-SiC crystals (2 inch in diameter) on the 8° off- axis C-face 6H-SiC seeds, inclined toward [11-20] direction. The growth of crystals by physical vapour transport method (PVT) was realized with the open seed backside in the experimental setup with graphite resistive heater. Some of the crystals were doped with cerium in the purpose of the 4H polytype growth stabilization. For Ce-doped crystals the seed backside carbonization process was decreased in comparison with such effect observed in the undoped SiC crystals.
Authors: Katarzyna Racka, Emil Tymicki, Krzysztof Grasza, Marcin Raczkiewicz, Rafał Jakieła, Michal Kozubal, Elzbieta Jurkiewicz-Wegner, Andrzej Brzozowski, Ryszard Diduszko, Miroslaw Piersa, Kinga Kościewicz, Mariusz Pawłowski, Jerzy Krupka
Abstract: Results of vanadium doping in PVT SiC bulk growth by the use of the seeding technique with an open seed backside are shown. Structural and electrical properties of 4H and 6H-SiC:V were investigated by a variety of experimental methods. In the crystal studied, the solubility limit of V in SiC was exceeded and structural defects consisting of V-rich precipitates occured. Electrical properties of this crystal were determined by the V3+/V4+ acceptor level. The V3+ charge state of vanadium was formed by compensating shallow donors (mainly nitrogen) and for both 4H and 6H polytypes it was detectable in optical absorption (in the near-IR range) and electron paramagnetic resonance.
Authors: Yuri N. Makarov, D.P. Litvin, A.V. Vasiliev, A.S. Segal, S.S. Nagalyuk, Heikki Helava, M.I. Voronova, K.D. Scherbachov
Abstract: In this paper, we report on the current status of our technology for the commercial production of 3” 6H-SiC substrates, including PVT growth [1] of more than 3” diameter and up to 20 mm long 6H-SiC boules, post-growth processing of the boules, and characterization of the produced wafers. We discuss the preparation of SiC sources and seeds, the initial transient stage of the growth, the distribution of temperature in the growth crucible, and the Si/C ratio in the vapor. Special attention is given to the rise of the process stability and the reduction of crystallographic defects, including micropipes (open core screw dislocations), low-angle grain boundaries, foreign polytype inclusions, and graphite inclusions [2,3].
Authors: Rainer Hock, Katja Konias, L. Perdicaro, Andreas Magerl, Philip Hens, Peter J. Wellmann
Abstract: We have investigated thermally induced strain in the SiC crystal lattice during physical vapor transport bulk growth. Using high energy x-ray diffraction lattice plane bending was observed in-situ during growth. With increasing growth rate increasing lattice plane bending and, hence, strain was observed. A comparison with numerical modeling of the growth process shows that the latter is related to the heat of crystallization which needs to be dissipated from the crystal growth front. The related temperature gradient as driving force for the dissipation of the heat of crystallization causes lattice plane bending. Optimization of the growth process needs to consider such effects.

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