碳化硅同质外延质量影响因素的分析与综述

摘要/Abstract

摘要： 碳化硅(SiC)外延质量会直接影响器件的性能和使用寿命,在SiC器件应用中起到关键作用。SiC外延质量一方面受衬底质量的影响,例如衬底的堆垛层错(SF)会贯穿到外延层中形成条状层错(BSF),螺位错(TSD)会贯穿到外延层中形成坑点或Frank型层错(Frank SF)等。另一方面受到外延工艺的影响,如在外延过程中衬底的基平面位错(BPD)受应力等条件作用会滑移形成Σ形基平面位错(Σ-BPD),衬底的TSD或刃位错(TED)会衍生为腐蚀坑(Pits),以及新产生SF和硅滴等。因此,获得高质量的SiC外延晶片需要从优选SiC衬底和优化外延工艺两方面入手。本文对外延生长过程中晶体缺陷如何转化并影响器件性能进行了系统分析和综述,并基于北京天科合达半导体股份有限公司量产的高质量6英寸SiC衬底,探讨了常见缺陷,如BPD、层错、硅滴和Pits等的形成机理及其控制技术,并对Σ-BPD的产生机理和消除方法进行研究,最终获得了片内厚度和浓度均匀性良好、缺陷密度低的外延产品,完成了650和1 200 V外延片产品的开发和产业化工作。

关键词: 碳化硅, 同质外延, 外延生长, 缺陷, 位错, 小坑

Abstract: The performance and lifetime of silicon carbide (SiC) devices are directly affected by the quality of SiC epitaxial films. On the one hand, the quality of SiC epitaxial films is affected by the quality of substrates. For examples, the stacking faults (SF) in substrates penetrate into the epitaxial layer, forming bar-shaped stacking faults (BSF), and the threading screw dislocation (TSD) penetrate into the epitaxial layer to form pits or Frank-type stacking faults (Frank SF). On the other hand, the quality of SiC epitaxial films is also influenced by the epitaxial growing process. For examples, basal plane dislocation (BPD) in the substrate form Σ-basal plane dislocation (Σ-BPD) in the epitaxial layer under thermal stress or other unstable conditions, the TSD and threading edge dislocation (TED) in the substrate may be etched and derived into pits, and SF and silicon droplets may also be produced. Therefore, high quality SiC substrates and optimized epitaxial growing process are both crucial for obtaining high-quality silicon carbide epitaxial wafers. In this article, based on the SiC epitaxial films grown on 6 inch SiC substrates batch-produced by TankeBlue Company, the defects reproducing process in substrates during epitaxial growing were analyzed, and the formation mechanism and controlling technology of common defects such as BPD, SF, silicon droplets and pits were overviewed. The generation mechanism of Σ-BPD and its eliminating methods were also explored. Finally, we obtained the mass-production technologies of SiC epitaxial films with good thickness and concentration uniformity, and low defect density, which are qualified for making 650 and 1 200 V SiC-based MOSFETs.

Key words: SiC, homo-epitaxial, epitaxial growth, defect, dislocation, pit

中图分类号:

郭钰, 刘春俊, 张新河, 沈鹏远, 张博, 娄艳芳, 彭同华, 杨建. 碳化硅同质外延质量影响因素的分析与综述[J]. 人工晶体学报, 2024, 53(2): 210-217.

GUO Yu, LIU Chunjun, ZHANG Xinhe, SHEN Pengyuan, ZHANG Bo, LOU Yanfang, PENG Tonghua, YANG Jian. Analysis and Review of Influencing Factors of SiC Homo-Epitaxial Wafers Quality[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2024, 53(2): 210-217.

参考文献

[1] BRANDER R W, SUTTON R P. Solution grown SiC p-n junctions[J]. Journal of Physics D: Applied Physics, 1969, 2(3): 309-318.
[2] IKEDA M, HAYAKAWA T, YAMAGIWA S, et al. Fabrication of 6H-SiC light-emitting diodes by a rotation dipping technique: electroluminescence mechanisms[J]. Journal of Applied Physics, 1979, 50(12): 8215-8225.
[3] ZIEGLER G, LANIG P, THEIS D, et al. Single crystal growth of SiC substrate material for blue light emitting diodes[J]. IEEE Transactions on Electron Devices, 1983, 30(4): 277-281.
[4] MATSUNAMI H, NISHINO S, ONO H. IVA-8 heteroepitaxial growth of cubic silicon carbide on foreign substrates[J]. IEEE Transactions on Electron Devices, 1981, 28(10): 1235-1236.
[5] JENNINGS V J, SOMMER A, CHANG H C. The epitaxial growth of silicon carbide[J]. Journal of the Electrochemical Society, 1966, 113(7): 728.
[6] CAMPBELL R B, CHU T L. Epitaxial growth of silicon carbide by the thermal reduction technique[J]. Journal of the Electrochemical Society, 1966, 113(8): 825.
[7] MUENCH W V, PFAFFENEDER I. Epitaxial deposition of silicon carbide from silicon tetrachloride and hexane[J]. Thin Solid Films, 1976, 31(1/2): 39-51.
[8] YOSHIDA S, SAKUMA E, OKUMURA H, et al. Heteroepitaxial growth of SiC polytypes[J]. Journal of Applied Physics, 1987, 62(1): 303-305.
[9] NISHINO S, POWELL J A, WILL H A. Production of large-area single-crystal wafers of cubic SiC for semiconductor devices[J]. Applied Physics Letters, 1983, 42(5): 460-462.
[10] KURODA N, SHIBAHARA K, YOO W, et al. Step-controlled VPE growth of SiC single crystals at low temperatures[C]//Extended Abstracts of the 1987 Conference on Solid State Devices and Materials. August 25-27, 1987. Nippon Toshi Center, Tokyo, Japan. The Japan Society of Applied Physics, 1987: 032156.
[11] KONG H, KIM H J, EDMOND J A, et al. Growth, doping, device development and characterization of CVD beta-SiC epilayers on Si(100) and alpha-SiC(0001)[J]. MRS Proceedings, 1987, 97: 233.
[12] JR A B A, ROWLAND L B. Homoepitaxial vpe growth of SiC active layers[J]. Physica Status Solidi (b), 1997, 202(1):263-279.
[13] RUPP R, MAKAROV N Y, BEHNER H, et al. Silicon carbide epitaxy in a vertical CVD reactor: experimental results and numerical process simulation[J]. Physica Status Solidi (b),1997,202(1):281-304.
[14] KIMOTO T, ITOH A, MATSUNAMI H. Step-controlled epitaxial growth of high-quality SiC layers[J]. Physica Status Solidi (b), 1997, 202(2): 247-262.
[15] THOMAS B, BARTSCH W, STEIN R A, et al. Properties and suitability of 4H-SiC epitaxial layers grown at different CVD systems for high voltage applications[J]. Materials Science Forum, 2004, 493(457-460): 181-184.
[16] LA VIA F, CAMARDA M, CANINO A, et al. Fast growth rate epitaxy by chloride precursors[J]. Materials Science Forum, 2013, 740/741/742: 167-172.
[17] LARKIN D J, SRIDHARA S G, DEVATY R P, et al. Hydrogen incorporation in boron-doped 6H-SiC CVD epilayers produced using site-competition epitaxy[J]. Journal of Electronic Materials, 1995, 24(4): 289-294.
[18] LARKIN D J, NEUDECK P G, POWELL J A, et al. Site-competition epitaxy for superior silicon carbide electronics[J]. Applied Physics Letters, 1994, 65(13): 1659-1661.
[19] LARKIN D J. SiC dopant incorporation control using site-competition CVD[J]. Physica Status Solidi (b), 1997, 202(1): 305-320.
[20] WANG R J, BHAT I B, CHOW T P. Epitaxial growth of n-type SiC using phosphine and nitrogen as the precursors[J]. Journal of Applied Physics, 2002, 92(12): 7587-7592.
[21] KIMOTO T, NAKAZAWA S, HASHIMOTO K, et al. Reduction of doping and trap concentrations in 4H-SiC epitaxial layers grown by chemical vapor deposition[J]. Applied Physics Letters, 2001, 79(17): 2761-2763.
[22] TSUCHIDA H, KAMATA I, JIKIMOTO T, et al. Epitaxial growth of thick 4H-SiC layers in a vertical radiant-heating reactor[J]. Journal of Crystal Growth, 2002, 237/238/239: 1206-1212.
[23] BURK A A, TSVETKOV D, BARNHARDT D, et al. SiC epitaxial layer growth in a 6×150 mm warm-wall planetary reactor[J]. Materials Science Forum, 2012, 717/718/719/720: 75-80.
[24] KOJIMA K, SUZUKI T, KURODA S, et al. Epitaxial growth of high-quality 4H-SiC carbon-face by low-pressure hot-wall chemical vapor deposition[J]. Japanese Journal of Applied Physics, 2003, 42(Part 2, No. 6B): L637-L639.
[25] THOMAS B, ZHANG J E,MOEGGENBORG K, et al. Progress of SiC epitaxy on 150 mm substrates[J]. Materials Science Forum, 2015, 821/822/823: 161-164.
[26] MATTIA M, EGIDIO C, DANILO C, et al. Development of n-type epitaxial growth on 200 mm 4H-SiC wafers for the next generation of power devices[J]. Microelectronic Engineering, 2023, 274(1): 111976.
[27] THOMAS B, ZHANG J E, CHUNG G Y, et al. Homoepitaxial chemical vapor deposition of up to 150 μm thick 4H-SiC epilayers in a 10×100 mm batch reactor[J]. Materials Science Forum, 2016, 858: 129-132.
[28] KENNETH G I. Growth of very uniform silicon carbide epitaxial layers, US6063186A[P]. 1999-06-24.
[29] AYEDH H M, HALLÉN A, SVENSSON B G. Elimination of carbon vacancies in 4H-SiC epi-layers by near-surface ion implantation: influence of the ion species[J]. Journal of Applied Physics, 2015, 118(17): 175701.
[30] AYEDH H M, KVAMSDAL K E, BOBAL V, et al. Carbon vacancy control in p⁺-n silicon carbide diodes for high voltage bipolar applications[J]. Journal of Physics D: Applied Physics, 2021, 54(45): 455106.
[31] MIYAZAWA T, TSUCHIDA H. Point defect reduction and carrier lifetime improvement of Si- and C-face 4H-SiC epilayers[J]. Journal of Applied Physics, 2013, 113(8): 083714.
[32] RANA T, CHUNG G, SOUKHOJAK A, et al. Interfacial dislocation reduction by optimizing process condition in SiC epitaxy[J]. Materials Science Forum, 2022, 63(9): 99-103.
[33] ZHANG X A, NAGANO M, TSUCHIDA H. Basal plane dislocations in 4H-SiC epilayers with different dopings[J]. Materials Science Forum, 2012, 725: 27-30.
[34] KAMATA I, TSUCHIDA H, JIKIMOTO T, et al. Structural transformation of screw dislocations via thick 4H-SiC epitaxial growth[J]. Japanese Journal of Applied Physics, 2000, 39(12R): 6496.
[35] DANIELSSON Ö, FORSBERG U, JANZÉN E. Predicted nitrogen doping concentrations in silicon carbide epitaxial layers grown by hot-wall chemical vapor deposition[J]. Journal of Crystal Growth, 2003, 250(3/4): 471-478.
[36] TSVETKOV V F, ALLEN S T, KONG H S, et al. Recent progress in SiC crystal growth[C]//International Conference on Silicon Carbide and Related Materials, 1995, 142: 317.
[37] LENDENMANN H, DAHLQUIST F, JOHANSSON N, et al. Long term operation of 4.5kV PiN and 2.5kV JBS diodes[J]. Materials Science Forum, 2001, 353/354/355/356: 727-730.
[38] BERGMAN P, LENDENMANN H, NILSSON P Å, et al. Crystal defects as source of anomalous forward voltage increase of 4H-SiC diodes[J]. Materials Science Forum, 2001, 353/354/355/356: 299-302.
[39] LENDENMANN H, BERGMAN P, DAHLQUIST F, et al. Degradation in SiC bipolar devices: sources and consequences of electrically active dislocations in SiC[J]. Materials Science Forum, 2003, 433/434/435/436: 901-906.
[40] MUZYKOV P G, KENNEDY R M, ZHANG Q, et al. Physical phenomena affecting performance and reliability of 4H-SiC bipolar junction transistors[J]. Microelectronics Reliability, 2009, 49(1): 32-37.
[41] SKOWRONSKI M, HA S. Degradation of hexagonal silicon-carbide-based bipolar devices[J]. Journal of Applied Physics, 2006, 99(1): 011101.
[42] YANG L, ZHAO L X, WU H W, et al. Characterization and reduction of defects in 4H-SiC substrate and homo-epitaxial wafer[J]. Materials Science Forum, 2020, 1004: 387-392.
[43] STAHLBUSH R E, VANMIL B L, MYERS-WARD R L, et al. Basal plane dislocation reduction in 4H-SiC epitaxy by growth interruptions[J]. Applied Physics Letters, 2009, 94(4): 041916.
[44] CAPAN I, BORJANOVIC＇ V, PIVAC B. Dislocation-related deep levels in carbon rich p-type polycrystalline silicon[J]. Solar Energy Materials and Solar Cells, 2007, 91(10): 931-937.
[45] NA M, BAHNG W, JANG H, et al. Effects of stress on the evolution of Σ-shaped dislocation arrays in a 4H-SiC epitaxial layer[J]. Journal of Applied Physics, 2021, 129(24): 245101.
[46] LI Z, ZHANG X A, ZHANG Z H, et al. Microstructure of interfacial basal plane dislocations in 4H-SiC epilayers[J]. Materials Science Forum, 2019, 954: 77-81.
[47] NISHIO J, KUDOU C, TAMURA K, et al. C-face epitaxial growth of 4H-SiC on quasi-150-mm diameter wafers with high throughput[J]. Materials Science Forum, 2014, 778/779/780: 109-112.
[48] AOKI M, KAWANOWA H, FENG G, et al. Characterization of bar-shaped stacking faults in 4H-SiC epitaxial layers by high-resolution transmission electron microscopy[J]. Japanese Journal of Applied Physics, 2013, 52(6R): 061301.
[49] CAMARDA M, CANINO A, LA MAGNA A, et al. Structural and electronic characterization of (2, 3₃) bar-shaped stacking fault in 4H-SiC epitaxial layers[J]. Applied Physics Letters, 2011, 98(5): 051915.
[50] SUO H, YAMASHITA T, ETO K, et al. Observation of multilayer Shockley-type stacking fault formation during process of epitaxial growth on highly nitrogen-doped 4H-SiC substrate[J]. Japanese Journal of Applied Physics, 2019, 58(2): 021001.
[51] ASAFUJI R, HIJIKATA Y. Generation of stacking faults in 4H-SiC epilayer induced by oxidation[J]. Materials Research Express, 2018, 5(1): 015903.
[52] DONG L, SUN G S, YU J, et al. Mapping of micropipes and downfalls on 4H-SiC epilayers by Candela optical surface analyzer[C]//2012 IEEE 11th International Conference on Solid-State and Integrated Circuit Technology. October 29-November 1, 2012, Xi'an, China. IEEE, 2013: 1-3.
[53] KONSTANTINOV A O, HALLIN C, PÉCZ B, et al. The mechanism for cubic SiC formation on off-oriented substrates[J]. Journal of Crystal Growth, 1997, 178(4): 495-504.
[54] OKADA T, KIMOTO T, YAMAI K, et al. Crystallographic defects under device-killing surface faults in a homoepitaxially grown film of SiC[J]. Materials Science and Engineering: A, 2003, 361(1/2): 67-74.
[55] BENAMARA M, ZHANG X, SKOWRONSKI M, et al. Structure of the carrot defect in 4H-SiC epitaxial layers[J]. Applied Physics Letters, 2005, 86(2): 021905.
[56] OKADA T, KIMOTO T, NODA H, et al. Correspondence between surface morphological faults and crystallographic defects in 4H-SiC homoepitaxial film[J]. Japanese Journal of Applied Physics, 2002, 41: 6320-6326.
[57] TSUCHIDA H, KAMATA I, NAGANO M. Investigation of defect formation in 4H-SiC epitaxial growth by X-ray topography and defect selective etching[J]. Journal of Crystal Growth, 2007, 306(2): 254-261.
[58] 孙国胜, 杨霏, 柏松, 等. 4H-碳化硅衬底及外延层缺陷术语[S]. T/CASA 004.1-2018, 北京, 2018.
SUN G S, YANF F, BO S, et al. 4H-Silicon carbide substrate and epitaxial layer defect terms[S]. T/CASA 004.1-2018, Beijing, 2018 (in Chinese).
[59] POWELL J A, LARKIN D J. Process-induced morphological defects in epitaxial CVD silicon carbide[J]. Physica Status Solidi (b), 1997, 202(1): 529-548.
[60] KIMOTO T, CHEN Z Y, TAMURA S, et al. Surface morphological structures of 4H-, 6H- and 15R-SiC (0001) epitaxial layers grown by chemical vapor deposition[J]. Japanese Journal of Applied Physics, 2001, 40(5R): 3315.
[61] KIMOTO T, MIYAMOTO N, MATSUNAMI H. Performance limiting surface defects in SiC epitaxial p-n junction diodes[J]. IEEE Transactions on Electron Devices, 1999, 46(3): 471-477.
[62] OHTANI N, USHIO S, KANEKO T, et al. Tunneling atomic force microscopy studies on surface growth pits due to dislocations in 4H-SiC epitaxial layers[J]. Journal of Electronic Materials, 2012, 41(8): 2193-2196.
[63] 孙国胜, 杨霏, 柏松, 等. 4H-SiC衬底及外延层缺陷图谱[S]. T/CASA 004.2-2018, 北京, 2018.
SUN G S, YANF F, BO S, et al. Defect map of 4H-SiC substrate and epitaxial layer[S]. T/CASA 004.2-2018, Beijing, 2018 (in Chinese).
[64] KUDOU C, ASAMIZU H, TAMURA K, et al. Influence of epi-layer growth pits on SiC device characteristics[J]. Materials Science Forum, 2015, 821/822/823: 177-180.