晶转埚转以及拉速对单晶硅生产过程的影响分析

单晶硅属于当前技术应用当中十分重要的一种半导体材料，其应用在电子信息技术领域以及太阳能技术领域当中的程度不断提升。当前单晶硅材料应用程度提升，也进一步增强了单晶硅在质量上的要求。换言之，单晶硅的杂质要求更高，加强杂质去除或者控制单晶硅当中的杂质氧含量就显得十分重要。本文侧重研究晶埚转以及拉速对单晶硅生产过程的影响分析。     

锗掺杂磁控直拉单晶硅太阳电池

介绍了锗掺杂浓度为(1～1.5)×1019cm-3的10Ω·cm磁控直拉单晶硅衬底上BSFR(back surface field and reflection)和BSR(back surface reflection)太阳电池的制备和电性能.BSR锗掺杂单晶硅太阳电池的AM0效率最高为12.3%.BSFR锗掺杂单晶硅太阳电池的AM0效率达到15%.利用1MeV的高能电子对制备的锗掺杂单晶硅太阳电池进行了辐照实验.作为对比,对全部常规10Ω·cm的CZ单晶硅太阳电池也进行了实验.结果表明,锗掺杂浓度为(1～1.5)×1019cm-3的磁控直拉单晶硅太阳电池的电性能和抗辐照性能与常规直拉硅太阳电池基本相同.利用锗掺杂磁控直拉单晶硅片机械强度较高的优点,可以降低太阳电池生产过程破损率.     

锗掺杂磁控直拉单晶硅太阳电池

介绍了锗掺杂浓度为(1～1.5)×1019cm-3的10Ω·cm磁控直拉单晶硅衬底上BSFR(back surface field and reflection)和BSR(back surface reflection)太阳电池的制备和电性能.BSR锗掺杂单晶硅太阳电池的AM0效率最高为12.3%.BSFR锗掺杂单晶硅太阳电池的AM0效率达到15%.利用1MeV的高能电子对制备的锗掺杂单晶硅太阳电池进行了辐照实验.作为对比,对全部常规10Ω·cm的CZ单晶硅太阳电池也进行了实验.结果表明,锗掺杂浓度为(1～1.5)×1019cm-3的磁控直拉单晶硅太阳电池的电性能和抗辐照性能与常规直拉硅太阳电池基本相同.利用锗掺杂磁控直拉单晶硅片机械强度较高的优点,可以降低太阳电池生产过程破损率.     

锗掺杂磁控直拉单晶硅太阳电池

介绍了锗掺杂浓度为（1～1.5) E19cm-3的10Ω·cm磁控直拉单晶硅衬底上BSFR (back surface field and reflection）和BSR(back surface reflection)太阳电池的制备和电性能. BSR锗掺杂单晶硅太阳电池的AM0效率最高为12.3%. BSFR锗掺杂单晶硅太阳电池的AM0效率达到15%. 利用1MeV的高能电子对制备的锗掺杂单晶硅太阳电池进行了辐照实验. 作为对比，对全部常规10Ω·cm的CZ单晶硅太阳电池也进行了实验. 结果表明，锗掺杂浓度为（1～1.5)E19cm-3的磁控直拉单晶硅太阳电池的电性能和抗辐照性能与常规直拉硅太阳电池基本相同. 利用锗掺杂磁控直拉单晶硅片机械强度较高的优点，可以降低太阳电池生产过程破损率.     

初始埚位对单晶少子寿命的影响

在KX260晶体生长系统上装备24英寸(1英寸=2.54 cm)热场,装料量为120 kg。采用5种不同的初始埚位(-50,-60,-70,-80,-90 mm),其他工艺参数相同的晶体生长工艺,拉制了5根200 mm、p型、晶向〈100〉、电阻率2Ω.cm的单晶硅棒。待硅棒冷却后,取片进行少子寿命和氧含量的测试,根据所得数据分析不同初始埚位对少子寿命的影响。由分析结果得出结论:随着初始埚位的提升,单晶硅棒少子寿命逐渐降低。结合实际生产利润及硅片品质需要,最后得到最适合晶体生长的初始埚位是-70 mm。     

原生直拉单晶硅中的铜沉淀规律

采用红外扫描仪、扫描电镜以及电子束诱生电流仪研究了不同温度和不同冷却速度下原生直拉单晶硅的铜沉淀规律.红外扫描仪观察发现:只有在热处理温度高于800℃的样品中才能观察到铜沉淀团,表明在原生单晶硅中铜沉淀温度为800℃.同时,红外扫描仪和电子束诱生电流谱仪照片显示,快冷(30K/s)时,形成高密度的小铜沉淀团;而慢冷(O.3K/s)导致低密度、巨大的星形铜沉淀团的形成.实验还发现慢冷所形成的星形铜沉淀团对少数载流子具有更强的复合强度.最后,讨论了原生直拉单晶硅中铜沉淀规律的机理.     

原生直拉单晶硅中的铜沉淀规律席珍强

采用红外扫描仪、扫描电镜以及电子束诱生电流仪研究了不同温度和不同冷却速度下原生直拉单晶硅的铜沉淀规律. 红外扫描仪观察发现：只有在热处理温度高于800℃的样品中才能观察到铜沉淀团，表明在原生单晶硅中铜沉淀温度为800℃. 同时，红外扫描仪和电子束诱生电流谱仪照片显示，快冷（30K/s）时，形成高密度的小铜沉淀团；而慢冷（0.3K/s）导致低密度、巨大的星形铜沉淀团的形成. 实验还发现慢冷所形成的星形铜沉淀团对少数载流子具有更强的复合强度. 最后，讨论了原生直拉单晶硅中铜沉淀规律的机理.     

晶体硅中的铁沉淀规律

研究了在直拉单晶硅和铸造多晶硅中经1100℃热处理快冷或慢冷条件下所形成的铁沉淀规律及其对少数载流子扩散长度的影响.红外扫描仪照片显示在直拉单晶硅中慢冷却形成的铁沉淀密度较低,而且其尺寸较大;在铸造多晶硅中,铁易在晶界上沉淀,沉淀规律也依赖于冷却速度.表面光电压仪测试结果表明:无论在直拉单晶硅材料中还是在铸造多晶硅材料中,快冷形成的铁沉淀对少数载流子扩散长度影响更大.实验结果可以用铁沉淀生成的热力学和动力学规律解释.     

晶体硅中的铁沉淀规律

研究了在直拉单晶硅和铸造多晶硅中经110 0℃热处理快冷或慢冷条件下所形成的铁沉淀规律及其对少数载流子扩散长度的影响.红外扫描仪照片显示在直拉单晶硅中慢冷却形成的铁沉淀密度较低,而且其尺寸较大;在铸造多晶硅中,铁易在晶界上沉淀,沉淀规律也依赖于冷却速度.表面光电压仪测试结果表明:无论在直拉单晶硅材料中还是在铸造多晶硅材料中,快冷形成的铁沉淀对少数载流子扩散长度影响更大.实验结果可以用铁沉淀生成的热力学和动力学规律解释     

直拉法生长Si1-xGex单晶的数值模拟

利用数值模拟技术对Si1-xGex单晶生长过程中的热传输和温度分布情况进行了模拟分析,并以此为条件对晶体生长过程中不同阶段下,不同埚转速度对晶体生长稳定性的影响进行了对比分析,获得了相应的数据.对优化晶体生长条件参数、提高晶体生长稳定性和晶体质量具有较好的指导意义.     

Quantitative optical in-situ measurement of the dissolution rate of the silica crucible in the silicon Czochralski process

The dissolution of the silica crucible by the silicon melt acts as a source of oxygen doping in the growth of silicon single crystals by the Czochralski-method. Literature data on the dissolution rate of silica in silicon melts are available up to now only from ex-situ measurements. In the present work, the silica dissolution rate is measured for the first time by an in-situ technique. The decrease of the thickness of the wall of a silica crucible of a laboratory-scale Czochralski-crucible containing silicon melt is measured quantitatively by optical laser interferometry. It is demonstrated that the influence of relevant growth parameters of the silicon Czochralski process like temperature of the silica crucible wall and pressure of the Argon gas can be detected and quantitatively related to the dissolution rate.     

坩埚位置对PVT生长AlN晶体过程中物质传输的影响

使用FEMAG晶体生长模拟仿真软件以及自主开发的PVT法有限元传质模块对全自动、双电阻加热物理气相沉积炉开展了AlN晶体生长工艺过程中不同坩埚埚位对温度场、过饱和度场及烧结体升华速率等影响的模拟仿真分析研究。模拟仿真结果表明:在给定工艺条件下,坩埚埚位较低时烧结体温度较高且内部温差较小,烧结体升华表面存在较大的Al蒸气分压梯度,各表面升华速率较快且均匀,籽晶衬底生长前沿温度场呈微凸分布,有利于晶体扩径及生长高质量晶体。随着坩埚埚位的上升,低温区向坩埚壁扩展,预烧结体内轴向及径向温度梯度增加,籽晶衬底附近径向温度梯度逐步降低,过饱和度区域扩大且增强。在坩埚埚位较高情况下,坩埚内原料升华变得不均匀,坩埚侧壁存在高过饱和区域,极易在坩埚壁上发生大量的AlN多晶沉积。模拟分析结果与大量实际晶体生长实验后的坩埚壁处沉积现象及剩余烧结体原料形态相符,较好地验证了模拟仿真分析结果的准确性。     

CZ法硅晶体生长过程中热输运和流体流动的数值研究

A global analysis of heat transfer and fluid flow in a real Czochralski single silicon crystal furnace is developed using the FLUENT package.Good agreement was obtained for comparisons of the power and crystal growth speed between the simulation and experimental data,and the effect of the length of the crystal on heat transfer and fluid flow was analyzed.The results showed that T_max increases and its location moves downward as the crystal length increases.The flow pattern in the melt does not change until the crystal grows to 900 mm.As the crystal length increases,the flow pattern in the first gas area only changes when the crystal length is less than 700 mm,but the flow pattern in the second area changes throughout the growth process.     

Silicon melt convection in large size Czochralski crucibles

The melt flow in large diameter crucibles during the growth of silicon (Si) single crystals of 300 mm diameter is characterized by turbulent large-scale velocity and temperature fluctuations. Strong efforts of the crystal growth industry are dedicated to the control of the interface shape and the related point defect distribution in the crystal, of the oxygen and particle transport in the melt, of the crucible overheating and of the conditions for dislocation free growth. Static and time-dependent electromagnetic fields offer new possibilities to meet the continuously increasing demands on crystal quality and yield improvement. Numerical simulation helps to investigate a wide range of possible process conditions, and to reduce experimental costs and time to market significantly. Depending on the required accuracy and available computation resources, two-dimensional (2D) or three-dimensional (3D) models are used. Temperature measurements in the melt, carried out during crystal growth and in model facilities, provide data for the verification of the numerical models, for direct process optimization and for a better understanding of the heat and mass transport behavior.     

单晶炉坩埚旋转速度控制系统设计

在单晶硅生产过程中,对单晶硅坩埚旋转速度有十分严格的要求。针对实际情况,本文采用神经网络自适应PID控制算法,通过80C196KB单片机实现对单晶炉的坩埚旋转速度精确平稳的控制。通过与模糊PID及传统PID算法比较表明,该方法在坩埚旋转过程中控制效果及抗干扰能力优于另两种控制方法。     

提拉法生长钆镓石榴石(GGG)晶体

用提拉法生长出了优质的钆镓石榴石(Gd3Ga5O12)晶体,晶体尺寸达φ35 × 70mm。详细描述 了晶体生长工艺过程,讨论了生长气氛对及坩埚形状对晶体生长的影响。     

φ60mm掺碲GaP单晶的研制

用高压液封直拉法制备大直径GaP单晶重要的是控制拉制参数,如埚位、氧化硼厚度、热场、晶体坩埚直径比等.实验采用浮舟技术控制晶体直径,调整和控制参数使得晶体固液界面在拉制过程中始终凸向熔体,这对获得单晶非常重要.分析了晶体中电阻率、载流子浓度分布及位错分布.采用X射线双晶衍射对晶体质量进行了测试分析.     

Towards implementation of floating cast method for growing large‐scale high‐quality multicrystalline silicon ingot using designed double crucibles

We report on our attempt to scale up the floating cast method to grow high‐quality multicrystalline silicon ingot using specially designed double crucibles. The cross section of the grown ingot showed the large crystal grain size originating from initially formed dendrite crystals around the top of the melt. By using double crucibles, the residual melt was spontaneously removed from the inner crucible to the outer one at the final stage of the crystal growth. Performance of small‐scale solar cells revealed no significant changes between the top and the bottom part of the ingot except the edge of the bottom due to the non‐uniform removal of the melt. This suggests that strong contact of the ingot with the crucible was successfully avoided by the double crucibles. Therefore, the floating cast method combined with specially designed double crucibles is concluded to be feasible, which could be implemented to realize high‐quality multicrystalline silicon ingot for practical size wafers. Copyright © 2013 John Wiley & Sons, Ltd.     

Laser beam controls crystal growth

Synthetic crystals of inorganic materials are often grown by pulling a seed (small single crystal) of the material slowly from the melt. During pulling the crystal is rotated slowly around a vertical axis. With the Czochralsky method, as this is called, it is difficult to control the diameter of the growing crystal, and irregular variations in the diameter generally give rise to imperfections in the crystal structure. The Philips Research Laboratories at Aachen have now evolved a new method in which a laser beam is used to measure and control the diameter of the crystal automatically throughout its growth. This new method can be applied practically independently of crystal material, crucible form, etc. and crystal diameters can be kept constant to within 1 per cent.