摘要
4H-SiC MPS是很有前途的半导体功率整流器。本文对4H-SiC MPS的工作机理进行了模拟分析，优化设计了器件结构，并对其功率损耗特性进行了研究。
模拟了4H-SiC MPS的输运特性，对其工作机理进行了二维分析。通过对器件体内各物理量的定量分析，得出PN结对肖特基的作用是通过其耗尽层和两PN结之间的间隙来影响肖特基的导电沟道这一结论。MPS结构的应用，在保留SBD正向特性的同时，大大提高了其反向特性，而碳化硅材料的应用更加强化了MPS的这一优势。
提出了一种新的4H-SiC MPS解析模型。基于此模型，提出在对正反向特性进行折衷时，如何选择合适的外延层掺杂浓度和厚度、肖特基接触和PN结网格宽度、PN结深度和掺杂浓度。通过对4H-SiC MPS击穿特性的二维模拟，提出如何选择合适的PN结深度、外延层掺杂浓度和厚度以及如何运用JTE终端技术来提高击穿电压。
建立了4H-SiC MPS的功率损耗的解析模型并对其功率损耗特性进行了计算。提出从功耗的角度考虑，4H-SiC MPS存在一个最佳工作温度。本文中所研究的4H-SiC MPS在770K左右具有最低的功耗。
4H-SiC MPS is a promising power semiconductor rectifier. The working mechanics, optimum design and power dissipation was studied in this thesis.
The transport characteristics of 4H-SiC MPS was simulated. The working mechanics of 4H-SiC MPS was two-dimensional analyzed. According to the analysis of physical quantities in the body, we got a conclusion that the effect of PN junction on Schottky is through its depletion layer and the gap between two PN junctions. The application of MPS structure improves the reverse characteristics and preserves the forward characteristics of SBD. And the application of Silicon carbide enhances the advantage of MPS structure.
A analytical model of 4H-SiC MPS was given. Based on this model, it was presented that how to select the thickness of epilayer, the doping concentration of epilayer, Schottky contact, the width of PN grid, the depth of PN junction and the doping concentration of PN junction for the trade-off between forward and reverse characteristics. It also put forward that how to select appropriate epilayer doping concentration and thickness, PN junction depth and JTE technology to increase the breakdown voltage of 4H-SiC MPS.
A power dissipation model of 4H-SiC MPS was established. The power dissipation of 4H-SiC MPS was calculated. The influences of temperature on SiC mobility, ionization rate and intrinsic carriers density were taken into account. We found that the 4H-SiC MPS has an optimal work temperature. For the MPS mentioned in this paper, the lowest power dissipation emerges at about 770K.
引文
[1] B.M.Wiliamovski, "Schottky diodes with high breakdown voltage", Solid-State Electronics, Vol.26, pp.491-493, 1983．
[2] B.J.Baliga, "The pinch rectifier: A low forward drop, high speed power diode". IEEE Electron Device Letters, Vol.EDL-5, pp. 194-1 96, 1984．
[3] B.J.Baliga, "Analysis of Junction Barrier Controlled Schottky Rectifier Characteristics", Solid-State Electronics, Vol.28, pp.1089-1093,1985．
[4] B.J.Baliga, "Analysis of a high voltage merged PiN/Schortky(MPS) rectifier", IEEE Electron Device Letters, Vol.EDL-8, pp.407-409, 1987
[5] R.Held, N.Kaminski and E. Nieman, "SiC merged p-n/Schottky rectifier for high voltage applications", Materials Science forum, Vols.264-268, pp. 1058-1060,1998．
[6] F.Dalquist, C.-M. Zetterlink, M.Ostling and K.Rortner, "Junction barrier diodes in 4H-SiC and 6H-SiC". Materials Science forum, Vols.264-268, pp. 1061-1064, 1998
[7] R.Held, M.Fullmann and E. Nieman, "SiC-Power Rectifiers", Materials Science forum, Vols.338-342, pp. 1407-141 0,2000
[8] K.Tone, J.H.Zhao, M.Weiner, etal, "Fabrication and Testing of 1000V-60A 4H-SiC MPS Diodes in an Inductive Half Bridge Circuit", Materials Science forum, Vols. 338-342, pp. 1187-11 90, 2000
[9] RAlexandrov, J.H.Zhao, W.Wright, et.al, "Demonstration of 140A, 800V 4H-SJC pin/Schottky barrier diodes with multi-step junction termination extension structures", Electronics Letters, Vol.37, No. 18, pp. 1139-1140, 30th August 2001
[10] A.Hefner, Jr., D.Beming, "Silicon Carbide Merged PiN Schottky Diodes Switching Characteristics and Evaluation for Power Supply Applications", in Proc. Conf. Rec. IEEE IAS Annu. Meeting, pp.2948-2954． , Oct.2000
[11] A.Hefner, Jr., "SiC Power Diodes Provide Breakthrough Performance for a Wide Range of Applications", IEEE Transactions On Power Electronics, Vol.16, No.2, pp.273-280, March 2001
[12] B.J.Baliga, "Trends in Power Semiconductor Devices", IEEE Transactions on Electron Devices, Vol.43, No.10, pp.1717-1731, October 1996
[13] S.F.Gilmartin, A.F.J.Murray, W.A.Lane, "A 1000V Merged P-N/Schottky (MPS) High-speed Low-loss Power Rectifier", Power Electronics and Variable Speed Drives, 21-23 September 1998, Conference Publication No.456, pp.375-380, 1998
[14] S.Sawant, B.J.Baliga, "4KV Merged PiN Schottky (MPS) Rectifiers", Proceedings of 1998 International Symposium on Power Semiconductor Devices & ICs, Kyoto, pp.297-300, 1998
[15] D. J. Larkin, P. G. Neudeck, J. A. Powell, L. G. Matus, Inst. Phys. Conf. Ser. No. 137, pp.51-54, 1994
[16] W. J. Schaffer, H. S. Kang, G. H. Neglay, J. W. Palmour Inst. Phys. Conf Ser. No.137,pp.155-159, 1994
[17] 张玉明，碳化硅材料与器件的研究，西安交通大学博士论文，1998年4月， 第25页
[18] Martin Ruff, Heinz Mitlehner, Reinhard Helbig, "SiC Devices: Physics and Numerical Simulation" IEEE Transactions on Electron Devices, vol. 41． NO. 6, pp. 1040-1054, JUNE 1994
[19] A.O.Konstantinov, Q.Wahab, N.nordell, et.al,"Ionization rates and critical fields in 4H silicon carbide", Appl. Phys. Lett.71(1) , pp.90-92, 7 July 1997
[20] R.Raghunathan, B.J.Baliga, "Measurement of Electron and Hole Impact lonization Coefficients for SiC", IEEE Int Symp On Power Semiconductor Devices and ICs, pp. 173-176, May 1997
[21] N.G.Wright, D.J.Morrison, C.M.Johnson et.al, "ElectroThermal Simulation of 4H-SiC Power Devices", Material Science Forum, Vols.264-268, pp.917-920, 1998
[22] R.Raghunathan, B.J.Baliga, "Temperature dependence of hole impact ionization coefficients in 4H and 6H-SiC", Solid-State Electronics, Vol.43, pp. 199-211, 1999
[23] R.Mickevicius, J.H.Zhao, "Monte Carlo study of electron transport in SiC", Journal of Applied Physics, Vol.83, No.6, pp.3 161-3 167, 15 March 1998
[24] H.Iwata, K.Itoh, "Theoretical Calculation of Electron Hall Mobility in n-type 4H-and 6H-SiC", Material Science Forum, Vols.338-342, pp.729-732, 2000
[25] R.Held, N.Kaminski, E.Niemann, "SiC Merged p-n/Schottky Rectifiers for High Voltage Applications", Material Science Forum, Vols.264-268, pp. 1057-1060． 1998
[26] U.Zimmermann, A.Hallen, B.Breitholtz, "Current Voltage Characteristics of High-Voltage 4H Silicon Carbide Diodes", Material Science Forum, Vols.338-342, pp.1323-1326,2000
[27] B.J.Baliga, Modern Power Devices, New York: Wiley, 1987．
[28] S.L.Tu, B.J.Baliga, "Controlling the characteristics of the MPS rectifier by variation og area of Schottky region", IEEE Transactions on electron devices,
Vol.ED-40, pp. 1307-1315,1993
[29]S.L.Tu, B.J.Baliga,"Optimization of the MPS rectifiers via variation of Schottky region area", ISPSD, pp. 109-112, 1991
[30]张玉明 张义门，P.Alexandrov,J.H.Zhao，“4H-SiC混合PN／Schottky二极管的研制”，半导体学报，Vol．22，No．3，2001pp．265-270(in English)
[31]D.Planson, M.L.Locatelli, S.Ortoland, J.P. Chante, H.Mitlehner, D.Stephani,"Periphery protection for silicon carbide devices: state of the art and simulation", Materials Science and Engineering, Vol.B46, pp.210-217, 1997.
[32]郝跃 彭军 杨银堂，“碳化硅宽带隙半导体技术”，科学出版社，2000
[33]张义门，张玉明，“碳化硅器件的需求背景及其发展现状”，电子科学技术评论，No．2，1996
[34]张玉明，张义门，“SiC功率器件”，电子科技导报，No．29，1996
[35]张玉明，张义门，罗晋升，“SiC、GaAs和Si的高温特性的比较”，固体电子学研究与进展，1997．3，17(3)，pp．305～310
[36]杨克武，潘静，杨银堂，“SiC半导体材料及其器件应用”，半导体情报，2000．4，37(2)，PP．13-15
[37]彭军，“SiC材料与器件”，半导体技术，1995．10，pp．33-40
[38]Philip G. Neudeck,"SiC TECHNOLOGY", NASA Lewis Research Center, 1998
[39]张玉明，张义门，罗晋升，“SiC肖特基势垒二极管的研制”，半导体学报，1999．11，20(11)，pp．1040～1043
[40]常远程，“碳化硅肖特基势垒二极管静态特性的研究”，西安电子科技大学硕士论文，2001
[41]尚也淳，“SiC材料和器件特性及其辐照效应的研究”，西安电子科技大学博士论文，2001
[42]T. Naito, M.Nemoto, A.Nishiura,"Fine pattern effect on leakage current and reverse recovery characteristics of MPS diode", Proceedinds of 2001 Internationa Symposium on Power Semiconductor Devices & ICs, Osaka, pp.227-230, 2001
[43]张玉明，牛新军，张义门，“SiC混合PiN／Schottky二极管(MPS)的研究”，第十二届全国半导体集成电路和硅材料学术会议，昆明，2001
[44]张玉明，牛新军，张义门，吕红亮，“碳化硅MPS的二维模拟”，第三届计算物理学术会议，乌鲁木齐，2001
[45]Yuming Zhang, Yimen Zhang, Xinjun Niu, Yuancheng Chang,"The Study OF Ni/4H-SiC SBD", The Sixth International Conference on Solid-State and Integrated-Circuit Technology(ICSICT),Shanghai,2001
[46]张玉明，张义门，罗晋生：“SiC肖特基势垒二极管的研制”，半导体学报，VoL.20，No.11,1999,PP.1040～1043
[47] 刘恩科 朱秉升 罗晋生。半导体物理学，国防工业出版社，1990
[48] S.M.Sze，半导体器件物理，电子工业出版社，1987．