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碳化硅材料特性及其应用浅析作者：王增泽来源：《新材料产业》2018年第01期一、碳化硅单晶特性以碳化硅（SiC）、氮化镓（GaN）为代表的宽禁带半导体材料，被称为第3代半导体材料。
与第1代、第2代半导体材料相比较，SiC具有高热导率、高击穿场强、高饱和电子漂移速率和高键合能等优点[1]。
SiC是目前发展最为成熟的宽禁带半导体材料之一，SiC在工作温度、抗辐射、耐击穿电压等性能方面具有明显的优势，其良好的性能可以满足现代电子技术的新要求，因此SiC被认为是半导体材料中最具有前途的材料之一[2]。
SiC由于与GaN的晶格常数及热膨胀系数相近（见表1），因此成为制造高端异质外延器件，如高电子迁移率晶体管（HEMT）、激光二极管（LDs）、发光二极管（LEDs）的理想衬底材料。
由于SiC材料拥有这些优异特性，许多国家相继投入了大量的资金对SiC进行了广泛深入的研究。
美国在20世纪末制订的“国防与科学计划”中就提出了关于宽禁带半导体的发展目标。
到2014年，美国联邦和地方政府提出全力支持以SiC半导体为代表的第3代宽禁带半导体，将拨款1.4亿美元用于提升美国在该新兴产业方面的国际竞争力。
近几年日本也有许多的动作，成立了新能源及工业技术发展组织，该组织发布了一系列基于SiC材料与器件的国家计划，主要发展高能量、高速度、高功率的开关器件。
我国在“十一五”重大专项“核高基”中也提出与国际同步开展宽禁带半导体功率器件研究，其中SiC单晶生长技术突破是最关键的。
SiC晶体的基本结构单元是Si-C四面体，如图1所示，原子间通过四面体SP3杂化结合在一起，并且有一定的极化。
目前，已发现的SiC晶型共有200多种，常见的晶型主要有3C、4H、6H及15R-SiC。
其中3C-SiC是立方结构，Si-C双原子层沿着[111]方向按照ABCABC……密堆方式排列；6H和4H-SiC均为六方结构，沿着[0001]方向堆垛，在[1120]投影方向，6H的排列次序为ABCACB……；4H的排列次序为ABCB……。
第52卷第8期2023年8月人㊀工㊀晶㊀体㊀学㊀报JOURNAL OF SYNTHETIC CRYSTALS Vol.52㊀No.8August,20236H to 3C Polytypic Transformation in SiC Ceramics During Brazing ProcessSHI Haojiang 1,ZHANG Ruiqian 1,LI Ming 1,YAN Jiazhen 2,LIU Zihao 2,BAI Dong 2(1.State Key Laboratory of Reactor Fuel and Materials,Nuclear Power Institute of China,Chengdu 610213,China;2.School of Mechanical Engineering,Sichuan University,Chengdu 610065,China)Abstract :In this paper,pure Ni foil was used as an intermediate layer to achieve brazing connection of 6H-SiC at 1100~1245ħ.The microstructure of the brazed joint and the interface between the brazed joint and the 6H-SiC substrate were studied to investigate the effect of brazing process on the crystal structure of SiC ceramics and provide theoretical and experimental data supports for brazing process design.The results show that a small amount of Ni atoms diffuse into the 6H-SiC ceramics during the brazing process and exist in solid solution form,which reduces the dislocation energy of 6H-SiC.The residual stress at the 6H-SiC /brazed joint interface increases with the increase of brazing temperature,and when the brazing temperature reaches 1245ħ,the (0001)plane of 6H-SiC at the interface slips along the 1/3<1100>direction,and the 6H-SiC is sheared to form 3C-SiC.Therefore,SiC ceramics can undergo phase transformation under the influence of stress and brazing material composition during the brazing process,and the effect of brazing process on their crystal structure and properties should be considered for SiC ceramics used in special environments.Key words :6H-SiC;3C-SiC;phase transformation;brazing;residual stressCLC number :O469㊀㊀Document code :A ㊀㊀Article ID :1000-985X (2023)08-1516-07SiC 陶瓷在钎焊过程中的6H 到3C 多型相变石浩江1,张瑞谦1,李㊀鸣1,颜家振2,刘自豪2,白㊀冬2(1.中国核动力研究设计院,反应堆燃料及材料国家重点实验室,成都㊀610213;2.四川大学机械工程学院,成都㊀610065)摘要:为探究钎焊过程对SiC 陶瓷晶体结构的影响,为钎焊工艺设计提供理论及试验数据支撑,本研究采用纯Ni 箔作为中间层在1100~1245ħ下实现了6H-SiC 的钎焊连接,并研究了焊缝以及6H-SiC 基体与焊缝界面处的微观形貌㊂研究结果表明,少量Ni 原子在钎焊过程中会扩散进入6H-SiC 陶瓷,并以固溶形式存在,降低了6H-SiC 层错能㊂随着钎焊温度升高,6H-SiC /焊缝界面处的焊后残余应力增大,当钎焊温度达到1245ħ时,界面处的6H-SiC 的(0001)面沿1/3<1100>方向产生滑移,6H-SiC 切变形成3C-SiC㊂因此,SiC 陶瓷在钎焊过程中受应力和钎料组成元素的作用发生相变,针对特殊环境使用的SiC 陶瓷需要斟酌钎焊工艺对其晶体结构及性能的影响㊂关键词:6H-SiC;3C-SiC;相变;钎焊;残余应力㊀㊀Received date :2023-01-03㊀㊀Foundation item :Research on Accident Tderant Fuel Technology for Nuclear Power (Phase Ⅱ)㊀㊀Biography :SHI Haojiang(1994 ),male,from Sichuan province,doctor,assistant research fellow.E-mail:myzxshj@ ㊀㊀Corresponding author :YAN Jiazhen,doctor,associate professor.E-mail:yanjiazhen@0㊀IntroductionSiC has a variety of crystal structures,such as hexagonal structure,cubic structure,and rhomboidal structure.Among them,the cubic SiC has only one stacking sequence,that is ABC ABC along the [0001]packing axis.SiC with this structure is called 3C-SiC,which is also known as β-SiC.All the other SiC crystals are collectively referred to as α-SiC.The hexagonal SiC with a stacking sequence of ABCACB along the packing axis is called 6H-SiC,㊀第8期SHI Haojiang et al:6H to3C Polytypic Transformation in SiC Ceramics During Brazing Process1517㊀and it is the most commonly seen SiC crystal in theα-SiC.SiC polytypes can transform to each other under certain conditions.Vlaskina et al[1-2]found that3C-SiC spontaneously transforms to6H-SiC at2000ħ.Parish et al[3]also observed the transformation from3C-SiC to6H-SiC at1440ħunder9dpa neutron irradiation.Due to the irradiation influence,the transformation temperature from3C-SiC to6H-SiC can be significantly reduced to1440ħ.In conclusion,β-SiC can transform toα-SiC through simple heat treatment at elevated temperatures. However,the transformation fromα-SiC toβ-SiC cannot be achieved by merely heat treatment.Zhu et al[4] investigated the deformation behavior and phase transformation in4H-SiC during nanoindentation process via molecular dynamics simulation.The simulation results show that it takes~9GPa of the shear stress for4H-SiC to transform to3C-SiC,where the atoms on(0001)plane of4H-SiC slips in1/3<1100>direction,resulting in the phase transformation from4H to3C.Yang et al[5]conducted a microindentation at1170ħwith a load of300g and a dwell time of30s on the6H-SiC,and the indented region shows that a6H to3C polytypic transformation occurs.The result confirms that SiC phase transformation can be induced by an applied stress.Based on the above investigations,a conclusion can be drawn that though it is difficult,the transformation fromα-SiC toβ-SiC is possible when enough stress is applied.Due to the significant differences in thermal conductivity,electrical conductivity,and radiation swelling resistance betweenα-SiC andβ-SiC,it is necessary for SiC ceramics to maintain structural stability in certain special service environments,such as structural materials in reactors and conductive materials in semiconductor components.Therefore studying the effect of the brazing process on the crystal structure of SiC ceramics is of great significance when SiC ceramics applications are often companied with joining.Nickel element is a common component element of SiC ceramic brazing fillers,and the reaction mechanism between nickel and SiC ceramic by a nickel foil as the brazing interlayer is reported in our previous work[6].In this paper,the polytypic transformation from6H-SiC to3C-SiC during brazing process is reported.The formation mechanism of the3C-SiC is investigated via HRTEM and SAED and well elaborated.1㊀Experimental sectionPressureless sintered6H-SiC ceramic blocks with dimension of15mmˑ10mmˑ5mm were brazed by a 0.1mm-thick pure nickel foil.The schematic diagram of the assembled SiC joint is shown in Fig.1(a).The detailed description about the SiC ceramics and nickel foil can be found in our previous work[6].The assembled specimens were heated to1100,1180,1245ħ,respectively,at a rate of15ħ/min with initial pressure of 3.5ˑ10-3Pa in vacuum furnace,and held for10min.Then the brazed samples were cooled down to room temperature in the furnace.The brazing heating curve is displayed in Fig.1(b).Fig.1㊀Schematic diagram of the assembled SiC joint(a)and the brazing heating curve(b)The detailed morphologies and compositions of the brazed seams were examined by field emission scanning electron microscope(FESEM,JSM-7500F)equipped with an energy dispersive spectrometer(EDS,Ultim Max). The EDS analysis using XPP correction method was operated under an accelerating voltage of15kV,a set of1518㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第52卷physical standards including SiO2,pure Ni and pure C are used for the analysis of element Si,Ni and C, respectively.Only the atomic fractions of Si and Ni are compared to characterize the reaction products in the joining seam due to the fact that carbon has low solubility in Ni-Si phases and can hardly be quantitatively analyzed.To further identify the phase structure of the joined seam,lift-out method is applied to the target location of interest using focused ion beam(FIB)on FEI Helios Nanolab600i.The thickness of the FIB sample decreases to50nm with a voltage range from2kV to30kV,and then analyzed by FEI Talos F200X and FEI Tecnai G2F20,operated at200kV,with an extreme field emission gun(X-FEG)electron source.The target FIB area locates at the interface between the transition zone and the6H-SiC.2㊀Results and discussionFig.2shows the microstructure of the SiC joints brazed at1100,1180,and1245ħ,respectively.As shown in Fig.2(b)and(d),the brazed seam and the6H-SiC ceramics are distinctly separated in the SiC joints brazed at1100and1180ħ.The interfaces are obvious and clear.When the brazing temperature increases to 1245ħ,the morphology of the interface changes,a transition zone forms between the brazed seam and the 6H-SiC.The transition zone consists of three phases,the island-likeδ-Ni2Si,scattered graphite flakes,and the 3C-SiC substrate[6].The chemical composition of the3C-SiC was analyzed under SEM mode,and the EDS results show that the mole fractions of C,Si and Ni in the target area are62.6%,35.7%and1.7%,respectively.The reaction process and mechanism between the nickel foil and6H-SiC can be found in our previous work[6].Fig.2㊀Microstructure of the SiC joints brazed at1100(a),(b),1180(c),(d),and1245ħ(e),(f)held for10min㊀第8期SHI Haojiang et al:6H to3C Polytypic Transformation in SiC Ceramics During Brazing Process1519㊀Fig.3shows the bright field images and corresponding HRTEM and SAED images of the FIB sample.3C-SiC, 6H-SiC andδ-Ni2Si are identified.EDS results are displayed in Table1.Notably,3C-SiC and6H-SiC both contain0.1%(atomic fraction)Ni.Since no nickel silicides are found in the3C-SiC and6H-SiC,Ni atoms should be ina form of solid solution atoms.Based on the HRTEM and SAED images after Fourier transform,it can be seen that 3C-SiC and6H-SiC share an obvious orientation relationship,the(0001)plane of the6H-SiC and the(111) plane of the3C-SiC are parallel to each other.The interface shown in Fig.3(f)is not crystallographically perfect, dislocations and terraces on(0110)6H plane can be found along the interface.The interface morphologies indicate that compared to the possibility of3C-SiC nucleating and growing on6H-SiC,it is more likely that3C-SiC is formed through the6H-SiC(0001)plane slipping along a specific direction.Table1㊀EDS analysis results of each area in Fig.3Location Composition/%Ni Si C Phase P10.135.964.06H-SiCP20.165.634.33C-SiCP368.032.0 δ-Ni2SiP465.035.0 δ-Ni2Si Transformation from6H-SiC to3C-SiC requires a certain shear stress applied on the slipping plane.As can be seen in Fig.2,no transition layer forms at the brazing temperature of1100and1180ħ,while it forms at a higher temperature of1245ħ.So it is highly possible that the shear stress comes from the residual stress that generates interface due to the CTE mismatch between the brazed seam and6H-SiC.The residual stress at the interface is estimated asσ=E S E RE S+E R(αR-αS)ΔT(1) whereσrepresents the residual stress,S stands for SiC,R stands for the reaction products near the interface,E represents the elastic modulus,αrepresents the linear expansion coefficient,andΔT represents the difference between the brazing temperature and the room temperature.The products near the interface are mainly Ni2Si and graphite,which are mixed up with each other and are uniformly distributed.So,the mixture of Ni2Si and graphite can be considered as a composite phase.The elastic modulus E of this composite phase is calculated according to the Voigt-Reuss formula[7]E composite=38E UL+58E LL(2)E UL=V N E N+V G E G(3)E LL=E G E NV N E G+V G E N(4) where N stands for Ni2Si,G stands for graphite,V and E stands for the volume modulus and elastic modulus, respectively.UL and LL represent the so-called upper and lower limit of the elastic modulus,respectively.The linear expansion coefficient of this composite phase is calculated using a more sophisticated formula,where the impact of stress is considered.The formula is written asαcomposite=αN V N K N+αG V G K GV N K N+V G K G(5) where V stands for volume fraction,K stands for the bulk modulus.Since graphite is anisotropic,therefore its morphology characteristics should be considered when selecting the physical property data of graphite.The graphite s physical properties along C axis are used since the graphite flake is nearly vertical to the brazed seam. All the physical properties used in these calculations are displayed in Table2.The results calculated according to1520㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第52卷the above formula show that the residual stress generated at the interface is1.76GPa when the joint cools down from1245ħ,and the residual stress is1.55GPa when the joint cools down from1100ħ.The residual stress increases with the increase of brazing temperature,providing a stronger force forα-SiC to transform.Fig.3㊀(a)TEM bright field image of the sample;(b),(c)HRTEM images of the3C/6H-SiC interface;(d)SAED image of the 3C/6H-SiC interface;(e),(f)higher magnification HRTEM images of the3C/6H-SiC interfaceTable2㊀Physical properties ofα-SiC,Ni2Si and graphite used in this paperPhase Elastic modulus,E/GPa Shear modulus,K/GPaCoefficient of linear expansion,α/(10-6K-1)Volume fraction/%α-SiC401.38[8]234[8] 3.5[8]Ni2Si168[9]189[9]13[10]51.3Graphite133.1[11]53.3[11]31[12]48.7 The calculated residual stress is much lower than the shear stress calculated by Zhu et al[4].However,there is no consensus on the critical value of stress thatα-SiC requires to transform toβ-SiC.Jepps et al[13]find that impurity element in SiC have a significant effect on the isomerism transition of SiC.When there are elements such as B and Al in SiC,α-SiC is more stable,andα-SiC can hardly transform toβ-SiC even under large shear stress. However,when the SiC contains N or P element,the stability ofβ-SiC is stronger,and only a small shear stress is required forα-SiC to transform toβ-SiC.Whitney et al[14]conducts a same experiment with the same conditions as Sokhor et al[15]reports,but fail to reproduce theα-SiC toβ-SiC transformation under the ambient pressure of3~7GPa at1200~1400ħ.But after Whitney et al adds BN intoα-SiC,the transformation fromα-SiC toβ-SiC occurred under the same circumstance.Therefore,impurity element has a significant effect on the(0001)6H slip activation energy ofα-SiC.As mentioned before,the presence of Ni element in SiC near the interface is confirmed,the existence of Ni should lower the magnitude of the residual stress thatα-SiC needs to transform toβ-SiC.Yuryeva et al[16-17] investigates the influence of Ni as an impurity element on the Si C bonding energy using first-principles calculations.They find that regardless of whether Ni exists in the form of a substitutional atom,an interstitial atom, or a more complex defect in SiC,the Si and C atoms around Ni atom are slightly displaced,resulting in the obvious weakening of the binding energy of the Si C covalent bond.This means that the isomeric transformation of SiC㊀第8期SHI Haojiang et al:6H to 3C Polytypic Transformation in SiC Ceramics During Brazing Process 1521㊀becomes easier.As shown in Fig.4,twins are found in the transformed SiC near the interface.The formation of twins in β-SiC indicates low stacking fault energy,which provides a high possibility for α-SiC to transform to β-SiC through (0001)6H plane sliding along the 1/3<1100>direction during the cooling process,turning the stackingsequence of ABCACB into ABCABC,as shown in Fig. 5.Fig.4㊀(a)TEM bright field image of the sample;(b),(c)HRTEM images of the twin grain in the 3C-SiC;(d)corresponding FFT pattern of the twin grain in the3C-SiCFig.5㊀HRTEM images of 6H-SiC (a)and 3C-SiC (b),and the schematic diagram of 6H-SiC transforming to 3C-SiC (c)1522㊀研究论文人工晶体学报㊀㊀㊀㊀㊀㊀第52卷3㊀ConclusionThe change of the SiC crystal structure during brazing process was investigated,and a polytypic transformation of6H-SiC to3C-SiC is reported in this paper.When6H-SiC ceramics was brazed using a0.1mm-thick pure nickel foil as the interlayer at1245ħ,the transformation of6H-SiC to3C-SiC is observed near the interface between the brazed seam and ceramic substrate.The microstructure and chemical composition of transformed SiC was analyzed and the6H-SiC to3C-SiC transformation mechanism is summarized as follow:1)A slight amount of Ni element exsists in the6H-SiC in a form of solid solution atom,and weakens the Si C bonding energy,lowering the stacking fault energy of6H-SiC.2)The CTE mismatch between the6H-SiC substrate and the brazed seam leads to residual stress after brazing, which drives the(0001)6H plane to slide along1/3<1100>direction,turning6H-SiC into3C-SiC.3)The brazing parameters and fillers should be carefully selected when brazing SiC for sophisticated applications since SiC polytypic transformation may occurs during the brazing process.References[1]㊀VLASKINA S I.3C-6H transformation in heated cubic silicon carbide3C-SiC[J].Semiconductor Physics Quantum Electronics andOptoelectronics,2011,14(4):432-436.[2]㊀VLASKINA S I,BUSINKAA@MAIL RU E M.Silicon carbide phase transition in as-grown3C-6H polytypes junction[J].Semiconductor PhysicsQuantum Electronics and Optoelectronics,2013,16(2):132-135.[3]㊀PARISH C M,KOYANAGI T,KONDO S,et al.Irradiation-inducedβtoαSiC transformation at low temperature[J].Scientific Reports,2017,7:1198.[4]㊀ZHU B,ZHAO D,ZHAO H W.A study of deformation behavior and phase transformation in4H-SiC during nanoindentation process viamolecular dynamics simulation[J].Ceramics International,2019,45(4):5150-5157.[5]㊀YANG J W,PIROUZ P.Theαңβpolytypic transformation in high-temperature indented SiC[J].Journal of Materials Research,1993,8(11):2902-2907.[6]㊀SHI H J,CHAI Y D,LI N,et al.Interfacial reaction mechanism of SiC joints joined by pure nickel foil[J].Journal of the European CeramicSociety,2020,40(15):5162-5171.[7]㊀GUZMÁN DE VILLORIA R,MIRAVETE A.Mechanical model to evaluate the effect of the dispersion in nanocomposites[J].Acta Materialia,2007,55(9):3025-3031.[8]㊀SENGUPTA P,SAHOO S S,BHATTACHARJEE A,et al.Effect of TiC addition on structure and properties of spark plasma sintered ZrB2-SiC-TiC ultrahigh temperature ceramic composite[J].Journal of Alloys and Compounds,2021,850:156668.[9]㊀ZHAO Y H,HOU H,ZHAO Y H,et al.First-principles study of the nickel-silicon binary compounds under pressure[J].Journal of Alloys andCompounds,2015,640:233-239.[10]㊀GEENEN F A,KNAEPEN W,MOENS F,et al.Anisotropic thermal expansion of Ni,Pd and Pt germanides and silicides[J].Journal of PhysicsD:Applied Physics,2016,49(27):275307.[11]㊀KIEWEL H,BUNGE H J,FRITSCHE L.Effect of orientation correlation on the elastic constants of polycrystalline materials[J].Textures andMicrostructures,1996,28(1/2):105-120.[12]㊀KELLY B T,WALKER P L.Theory of thermal expansion of a graphite crystal in the semi-continuum model[J].Carbon,1970,8(2):211-226.[13]㊀JEPPS N W,PAGE T F.Polytypic transformations in silicon carbide[J].Progress in Crystal Growth and Characterization,1983,7(1/2/3/4):259-307.[14]㊀WHITNEY E D,SHAFFER P T B.Investigation of the phase transformation between alpha-and beta-silicon carbide at high pressures[J].HighTemperatures-High Pressures,1969,1(1):107-110.[15]㊀SOKHOR M I,KONDAKOV V G,FELDGUN L I.Transition of silicon carbide from the hexagonal to the cubic phase under the influence of highpressures and high temperatures[J].Soviet Physics Doklady,1967,175(4):826.[16]㊀MEDVEDEVA N I,YURYEVAÉI,IVANOVSKII A L.Titanium,vanadium,and nickel impurities in3C-SiC:electronic structure and latticerelaxation effects[J].Semiconductors,2002,36(7):751-754.[17]㊀YURYEVA E I,IVANOVSKII A L.Electronic structure and chemical bonding of nickel impurities in cubic silicon carbide[J].Russian Journalof Coordination 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碳化硅衬底核心要素英文回答：The core elements of a silicon carbide substrate can be summarized as follows:1. Material Properties: Silicon carbide (SiC) is a compound semiconductor material known for its excellent thermal conductivity, high breakdown electric field strength, and wide bandgap. These properties make SiC a suitable choice for high-power and high-temperature applications.For example, SiC substrates are widely used in power electronic devices such as MOSFETs and Schottky diodes. The high thermal conductivity of SiC allows for efficient heat dissipation, while the wide bandgap enables the devices to operate at higher voltages and temperatures.2. Crystal Structure: SiC can exist in differentpolytypes, with the most common ones being 4H-SiC and 6H-SiC. The crystal structure of SiC influences its electrical and optical properties. For instance, the 4H-SiC polytype is often preferred for high-power applications due to its higher electron mobility.3. Substrate Quality: The quality of the SiC substrate is crucial for device performance. It includes factors such as crystal defects, surface roughness, and doping levels. High-quality SiC substrates are essential to ensure the reliability and efficiency of the devices fabricated on them.For example, a low defect density in the SiC substrate can lead to higher breakdown voltage and lower leakage current in power devices. Smooth surface morphology is also important for the growth of epitaxial layers and the integration of other materials.4. Epitaxial Growth: Epitaxy refers to the deposition of a crystalline layer on a substrate with a similarcrystal structure. In SiC technology, epitaxial growth iscommonly used to create a thin layer with specific doping and thickness requirements.For example, SiC epitaxial layers can be grown on SiC substrates to create a p-n junction for diode applications. The epitaxial layer can be doped with impurities to achieve the desired electrical characteristics.中文回答：碳化硅衬底的核心要素可以总结如下：1. 材料特性，碳化硅（SiC）是一种复合半导体材料，以其优异的热导率、高击穿电场强度和宽禁带宽度而闻名。
本科毕业论文6H-SiC MOSFET反型沟道电子迁移率的蒙特卡罗模拟本科毕业论文(科研训练、毕业设计)题目：6H-SiC MOSFET反型沟道电子迁移率的蒙特卡罗模拟姓名：学院：经济学院系：计划统计系专业：信息管理与信息系统年级：2007级学号：指导教师：职称：I开题报告1. 课题的研究背景SiC半导体材料是自第一代元素半导体材料(Si)和第二代化合物半导体材料(GaAs、GaP、InP等)之后发展起来的第三代宽带隙(WBS)半导体材料。
SiC材料由于具有宽带隙、高临界击穿电场、高热导率、高载流子饱和漂移速度等特点。
在高温、高频、大功率、光电子及抗辐射等方面具有巨大的应用潜力，许多国家相继投入了大量的资金对SiC进行了广泛深入的研究，并已在SiC晶体生长技术、关键器件工艺、光电器件开发、SiC集成电路制造等方面取得了突破，为军用电子系统和武器装备性能的提高，以及抗恶劣环境的电子设备提供了新型器件。
具体的说来，SiC材料的宽禁带使得其器件能在相当高的温度下(500℃以上)工作以及具有发射蓝光的能力。
高临界击穿场强电场决定了器件的高压、大功率性能。
高的饱和电子漂移速度和低介电常数决定了器件的高频、高速工作性能，高热导率意味着其导热性能好，可以大大提高电路的集成度，减少冷却散热系统，从而大大减少电子系统的体积。
再者，SiC具有很高的临界移位能，这使它具有高的抗电磁波冲击和高的抗辐射破坏的能力，SiC器件的抗中子能力至少是Si器件的四倍。
而SiC极低的少子产生速率也使其成为制备非易失性存储器的理想材料。
另一方面，SiC最大的优势还在于它是除了Si以外，唯一的半导体，这就使得制备SiC的MOS器件成为可能，并且能够热氧化生长SiO2SiC器件工艺和设备都与Si器件有很强的兼容性。
国内外在SiC研究方面已取得的主要成就如下：①SiC的同质多型和异质多型结构的可控合成理论；②生长大体积SiC晶体的多种改良的Lely方法；③包括局部外延和腐蚀过程的SiC器件微小化加工原则；④在蓝宝石上生长异质外延SiC薄膜(类似在蓝宝石上生长硅)的方法，它保证元件间的有效绝缘；⑤一系列新的SiC器件，包括压敏电阻、多色光二极管、核辐射和紫外辐射II传感器、极端条件下使用的温度和压力传感器等。
碳化硅的结构性质和用途【摘要】SiC陶瓷材料因其具有良好的耐磨、耐冲刷、耐腐蚀等优异的特性,被广泛应用机械、化工等行业。
本文采用双向加压的压制成型方法,通过无压烧结,成功的研制了在高耐磨、耐冲刷环境下所使用的喷砂机用喷砂嘴。
【关键字】引言结构与晶型碳化硅（SiC）俗称金刚砂，又称碳硅石是一种典型的共价键结合的化合物，自然界几乎不存在。
碳化硅晶格的基本结构单元是相互穿插的SiC4和CSi4四面体。
四面体共边形成平面层，并以顶点与下一叠层四面体相连形成三维结构。
SiC具有α和β两种晶型。
β－SiC的晶体结构为立方晶系，Si和C分别组成面心立方晶格；α－SiC 存在着4H、15R和6H等100余种多型体，其中，6H多型体为工业应用上最为普遍的一种。
在SiC的多种型体之间存在着一定的热稳定性关系。
在温度低于1600℃时，SiC以β－SiC形式存在。
当高于1600℃时，β－SiC缓慢转变成α－SiC的各种多型体。
4H－SiC在2000℃左右容易生成；15R和6H多型体均需在2100℃以上的高温才易生成；对于6H－SiC，即使温度超过2200℃，也是非常稳定的。
常见的SiC多形体列于下表：SiC常见多型体及相应的原子排列性能碳化硅（SiC）陶瓷，具有抗氧化性强，耐磨性能好，硬度高，热稳定性好，高温强度大，热膨胀系数小，热导率大以及抗热震和耐化学腐蚀等优良特性。
因此，已经在石油、化工、机械、航天、核能等领域大显身手，日益受到人们的重视。
例如，SiC陶瓷可用作各类轴承、滚珠、喷嘴、密封件、切削工具、燃汽涡轮机叶片、涡轮增压器转子、反射屏和火箭燃烧室内衬等等。
制备与烧结碳化硅是用石英砂、石油焦(或煤焦)、木屑(生产绿色碳化硅时需要加食盐)等原料在电阻炉内经高温冶炼而成。
碳化硅陶瓷的烧结方法有：无压烧结、热压烧结、热等静压烧结、反应烧结。
采用采用不同的烧结方法，SiC陶瓷具有各异的性能特点。
如就烧结密度和抗弯强度来说，热压烧结和热等静压烧结SiC陶瓷相对较多，反应烧结SiC相对较低。
半导体一些术语的中英文对照离子注入机ion implanterLSS理论Lindhand Scharff and Schiott theory 又称“林汉德-斯卡夫-斯高特理论”。
沟道效应channeling effect射程分布range distribution深度分布depth distribution投影射程projected range阻止距离stopping distance阻止本领stopping power标准阻止截面standard stopping cross section 退火annealing激活能activation energy等温退火isothermal annealing激光退火laser annealing应力感生缺陷stress-induced defect择优取向preferred orientation制版工艺mask-making technology图形畸变pattern distortion初缩first minification精缩final minification母版master mask铬版chromium plate干版dry plate乳胶版emulsion plate透明版see-through plate高分辨率版high resolution plate, HRP超微粒干版plate for ultra-microminiaturization 掩模mask掩模对准mask alignment对准精度alignment precision光刻胶photoresist又称“光致抗蚀剂”。
负性光刻胶negative photoresist正性光刻胶positive photoresist无机光刻胶inorganic resist多层光刻胶multilevel resist电子束光刻胶electron beam resistX射线光刻胶X-ray resist刷洗scrubbing甩胶spinning涂胶photoresist coating后烘postbaking光刻photolithographyX射线光刻X-ray lithography电子束光刻electron beam lithography离子束光刻ion beam lithography深紫外光刻deep-UV lithography光刻机mask aligner投影光刻机projection mask aligner曝光exposure接触式曝光法contact exposure method接近式曝光法proximity exposure method光学投影曝光法optical projection exposure method 电子束曝光系统electron beam exposure system分步重复系统step-and-repeat system显影development线宽linewidth去胶stripping of photoresist氧化去胶removing of photoresist by oxidation等离子［体］去胶removing of photoresist by plasma 刻蚀etching干法刻蚀dry etching反应离子刻蚀reactive ion etching, RIE各向同性刻蚀isotropic etching各向异性刻蚀anisotropic etching反应溅射刻蚀reactive sputter etching离子铣ion beam milling又称“离子磨削”。
碳化硅特性碳化硅是一种人工合成的碳化物，分子式为SiC。
通常是由二氧化硅和碳在通电后200 0℃以上的高温下形成的。
碳化硅理论密度是3.18g/cm3，其莫氏硬度仅次于金刚石，在9.2 -9.8之间，显微硬度3300kg/mm3，由于它具有高硬度、高耐磨性、高耐腐蚀性及较高的高温强度等特点，被用于各种耐磨、耐蚀和耐高温的机械零部件，是一种新型的工程陶瓷新材料。
纯碳化硅是无色透明的结晶,工业碳化硅有无色、淡黄色、浅绿色、深绿色、浅蓝色、深蓝色乃至黑色的,透明程度依次降低。
磨料行业把碳化硅按色泽分为黑色碳化硅和绿色碳化硅2类。
其中无色的至深绿色的都归入绿色碳化硅类,浅兰色的至黑色的则归入黑色碳化硅类。
黑色和绿色这2种碳化硅的机械性能略有不同,绿色碳化硅较脆,制成的磨具富于自锐性;黑碳化硅较韧。
碳化硅结晶结构是一种典型的共价键结合的化合物，自然界几乎不存在。
碳化硅晶格的基本结构单元是相互穿插的SiC4和CSi4四面体。
四面体共边形成平面层，并以顶点与下一叠层四面体相连形成三维结构。
SiC具有α和β两种晶型。
β－SiC的晶体结构为立方晶系，Si和C分别组成面心立方晶格；α－SiC存在着4H、15R和6H等100余种多型体，其中，6H多型体为工业应用上最为普遍的一种。
α-SiC是高温稳定型,β-SiC是低温稳定型。
β-SiC在2100～2400℃可转变为α-SiC,β-SiC可在1450℃左右温度下由简单的硅和碳混合物制得。
在温度低于1600℃时，SiC以β－SiC形式存在。
当高于1600℃时，β－SiC 缓慢转变成α－SiC的各种多型体。
4H－SiC在2000℃左右容易生成；15R和6H多型体均需在2100℃以上的高温才易生成；对于6H－SiC，即使温度超过2200℃，也是非常稳定的。
常见的SiC多形体列于下表：碳化硅的基本性能包括化学性质、物理机械性能、电学性质以及其他性质（亲水性好，远红外辐射性等）。
