本論文旨在進行具浮動式金屬護環設計高電壓SiC蕭基二極體之模擬設計與研製。基於SiC雜質摻雜擴散之不易，在不增加光罩數及所使用儀器成本之情形下，為提昇元件崩潰電壓，我們採用浮動式金屬護環進行SiC蕭基二極體之設計。
於本論文中，我們係以此邊緣終結結構進行二維數值模擬與實驗分析。於數值模擬方面，我們分析了磊晶層參雜條件對於崩潰電壓的影響以及比較不同終結結構對於崩潰電壓提升之影響。根據模擬所得結果，我們提出可供高崩潰電壓(>1000V)SiC蕭基二極體製作之邊緣終結結構設計。於實驗方面，我們分別以Ni及Au/Ti/Al作為歐姆接觸金屬並詳細分析了退火條件對於接觸電阻之影響。利用後者已可穩定製作出具有2.82×10-6 Ω-cm2低接觸電阻率之歐姆接觸。而於蕭基二極體之製作方面，我們係分別利用鋁、鈦、鎳、金等金屬作為蕭基金屬。實驗證實利用適當浮動式金屬護環設計可大幅提升蕭基二極體之崩潰電壓。實驗量測結果顯示，於分別利用鈦、鎳、金等三種蕭基金屬製得之二極體，其崩潰電壓已可達成超過1000 伏特之目標。

In this thesis, the design and fabrication of high voltage 4H-SiC Schottky barrier diodes (SBDs) with floating metal rings (FMR) edge termination (ET) scheme is presented. Two-dimension simulation to investigate the influence of FMR parameters such as the width, space, and the number of rings on the breakdown voltage (VBD) was conducted. Guidance for the device design to realize SBDs with VBD > 1000 V was proposed. The physical insight of the 4-H SiC SBDs under forward conducting and revere blocking was analyzed and discussed.
Based on a n/n+-4H-SiC epiwafer with a 10-m thick epilayer with a doping of 3×1015 cm-3, various ET schemes were proposed and investigated. As an example, theoretical calculation indicates that SBDs with a single-ring FMR design would have a breakdown voltage of 652 V. As compared to that of without ET design, an increase of 73 % in VBD has been obtained.
Experimental study of Ohmic contact to n-SiC using Ni and Au/Ti/Al was presented. It shows that the lowest contact resistivity of 2.82×10-6 Ω-cm2 for Au/Ti/Al contacts were obtained after annealing at 950℃ while for the Ni contacts the lowest resistivity of 5.14×10-7 Ω-cm2 were achieved at 1000℃. SiC SBDs have been successfully fabricated by employing Al, Ti, Ni and Au as the Schottky metal. Using a 3-ring FMR ET scheme, these unoptimized SBDs exhibit acceptable current-voltage characteristics with VBD in the 596 V - 923 V range.

[1]. B. J. Baliga, “Modern Power Devices”, Wiley, New York, 1987
[2]. H. P. Maruska and J. J. Tietjen, “The preparation and properties of vapor deposited single-crystalline GaN”, Appl. Phys. Lett., vol.15, pp. 327-329, 1996.
[3]. V. W. L. Chin, T. L. Tansley, and T. Osotchan, “Electron mobilities in gallium, indium, and aluminum nitrides”, J. Appl. Phys., vol. 75, pp. 7365-7372, 1994.
S. N. Mohammad, A. A. Salvador, and H. Morkoc, “Emerging gallium nitride based devices”, Proc. Of the IEEE, vol. 83, pp.1306-1355, 1995.
[4]. S. Keller, Y. F. Wu, G. Parish, N. Ziang, J. J. Xu, B. P. Keller, S. P. DenBaars, and U. K. Mishra, “Gallium nitride based high power hetrojunction field effect transistors: Process development and present status at UCSB”, IEEE Trans. Electron. Devices, vol. 48, pp. 552-559, 2001.
[5]. R. F. Davis, “III-V nitrides for electronic and optoelectronic applications”, IEEE Proc., vol 80, pp.702-712, 1991.
[6]. G. R. Fisher and P. Barnes, “Toward a unified view of polytypism in silicon carbide,” Phil. Mag. B, vol. 61, no. 2, pp. 217-236, Feb. 1990.
[7]. A. R. Powell and L. B. Rowland, Member, IEEE, “SiC Material-Progress, Status, and Potential Roadblocks”, IEEE Proc., vol 60, pp.942-955, 2002.
[8]. R. Singh, J. A. Cooper, Fellow, IEEE, M. R. Melloch, Fellow, IEEE, T. P. Chow, Senior Member, IEEE, and J. W. Palmour, Member, IEEE, “SiC Power Schottky and PiN Diodes”, IEEE Trans. Electron. Devices, vol. 49, pp. 665-672, 2002.
[9]. M. Bhatnagar, P. K. McLarty, and B. J. Baliga, “Silicon carbide high voltage (400 V) Schottky barrier diodes”, IEEE Electron Device Lett., vol. 13, p. 501, sept. 1992.
[10]. R. Rupp, M. Treu, A. Mauder, E. Griebl, W. Werner, W. Bartsch, and D. Stephani, “Performance and reliability issues of SiC Schottky diodes”, Mat. Sci. Forum, vol. 338-342, pp. 1167-1170, 2000.
[11]. Lien, F. C. T. So, and M. A. Nicolet, “An improved forward I-V method for nonideal Schottky diodes with high series resistance”, IEEE Trans. Electron Devices, vol. ED-31, no. 10, pp. 1502,1984.
[12]. Bohlin, “Generalized Norde plot including determination of the ideality factor”, J. Appl. Phys., vol. 60, no. 3, pp. 1223, 1986.
[13]. S. Y. Han, J. Y. Shin, B. T. Lee, and J. L. Lee, “Microstructural interpretation of Ni ohmic contact on n-type 4H-SiC ”, J. Vac. Sci. Technol. B 20, 1496 (2002).
[14]. R. Kakabakov, L. K. Kolaklieva, N. Hristeva, G. Lepoeva, and K. Zekentes, “Thermally Stable Low Resistivity Ohmic Contacts for High Power and Temperature SiC Device Applications”, Proc. 23rd International Conference on Microelectronics, 205 (2002).
[15]. S. Y. Han, K. H. Kim, J. K. Kim, H. W. Jang, K. H. Lee, N. K. Kim, E. D. Kim, and J. J. Lee, “Ohmic contact formation mechanism of Ni on n-type 4H-SiC”, Appl. Phys. Lett. 79, 1816 (2001).
[16]. Ts. Marinova, A. Kakanakova-Georgieva, V. Krastev, R. Kakanakov, M. Neshev, L. Kassamakova, O. Noblanc, C. Arnodo, S. Cassette, C. Brylinski, B. Pecz, G. Radnoczi, Gy. Vincze, “Nickel based ohmic contacts on SiC”, Materials Science and Engineering B46 (1997) 223-226.
[17]. J. Crofton, P. G. McMullin, J. R. Williams, and M. J. Bozack, “High-temperature ohmic contact to n-type 6H-SiC using nickel”, J. Appl. Phys., 1995, 77, (3), pp. 1317-1319.
[18]. L. G. Fursin, J. H. Zhao and M. Weiner, “Nickel ohmic contacts to p- and n-type 4H-SiC”, ELECTRONICS LETTERS 16th August 2001 vol. 37 no. 17.
[19]. S. K. Lee, C. M. Zetterling, M. Östling, J. P. Palmquist, H. Högberg, and U. Jansson, “Low resistivity ohmic titanium carbide contacts to n- and p-type 4H-silicon carbide”, Solid-State Electron., vol. 44, pp. 1179-1186, 2000.
[20]. S. K. Lee, C. M. Zetterling, E. Danielsson, M. Östling, J. P. Palmquist, H. Högberg, and U. Jansson, “Electrical characterization of TiC ohmic contacts to aluminum ion implanted 4H-Silicon carbide”, Appl. Physl. Lett., vol. 77, pp. 1478-1480, 2000.
[21]. S. K. Lee, E. Danielsson, C. M. Zetterling, M. Östling, J. P. Palmquist, H. Högberg, and U. Jansson, “The formation and characterization of epitaxial titanium carbide contacts to 4H-SiC”, Mat. Res. Soc. Proc., vol. 622, pp. T6.9 2000.
[22]. N. A. Papanicolaou, A. Edwards, M. V. Rao, J. A. Mittereder, and W. T. Anderson, “Ti/Al and Cr/Al ohmic contacts to n-type formed by furnace annealing”, Materials-Science-Forum, vol. 264-268, pp. 1407-1410, 1998.
[23]. J. Kriz, K. Gottfried, Th. Scholz, Ch. Kaufmann, T. GeBner, “Ohmic contacts to n-type polycrystalline SiC for high-temperature micromechanical applications”, Material Science and Engineering B46 (1997) 180-185.
[24]. G. S. Marlow and M. B. Das, Solid State Electron., 25 (2) (1982) pp. 91-94.
[25]. S. S. Cohen and G. Sh. Gildenblat, Metal-semiconductor contacts and Devices, Ch. 4, Academic Press, Orlando, 1986.
[26]. M. Bhatnagar, H. Nakanishi, S. Bothra, P. K. McLarty, and B. J. Baliga, “Edge Termination for SiC High Voltage Schottky Rectifiers”, IEEE, 1993.
[27]. Q. Zhang and T. S. Sudarshan, “Lateral current spreading in SiC Schottky diodes using metal overlap edge termination”, Solid-State Electronics, vol. 45, pp.1847-1850, 2001.
[28]. C. E. Weitzel, etc. “Silicon carbide high-power devices”, IEEE Trans. on Elec. Devices, vol. 43, pp. 1732-1741, 1996.
[29]. K. J. Schoen etc., “Design Considerations and Experimental Analysis of High-Voltage SiC Schottky Barrier Rectifiers”, IEEE Trans. Electron Devices, vol. 45, no. 7, pp. 1595-1604, 1998.
[30]. D. Alok and B. J. Baliga, “A Planar, Nearly Ideal, SiC Device Edge Termination”, Proc. of 1995 ISPSD & ICs, pp. 96-100, 1995.
[31]. B. J. Baliga etc., “A Simple Edge Termination for Silicon Carbide Devices with Nearly Ideal Breakdown Voltage”, IEEE Electron Device Lett., vol. 15, no. 10, pp. 394-395, 1994.
[32]. A. Itoh, T. Kimoto and H. Matsunami, “Efficient Power Schottky Rectifiers of 4H-SiC”, proc. International Symposium on Power Semiconductor Device & ICs, Yokohama, 1995.
[33]. Shui Jinn Wang and Jiann Tyng Tzeng, “The double-metal schottky power rectifier: an adjustable schottky barrier height low-power-loss diode”, submitted to 1997 International Conference on Solid State Device sand Materials (SSDM’97).
[34]. G. Constantinidis, “Processing Technologies for SiC”, pp. 161-170, IEEE, 1997.
[35]. M. Bhatnagar, H. Nakanishi, P. K. Mclarty, B. J. Baliga, B. Patnaik, and N. Parikh, “Comparison of Ti and Pt Silicon Carbide Schottky Rectifiers”, IEEE, 1992.