多晶硅还原炉系统余热回收利用

高纯的SiHCl_3与H_2在还原炉内1100℃左右高温下发生化学气相沉积反应,在硅芯上沉积而生成多晶硅,还原炉是多晶硅生产中电耗最高的设备,本文通过利用高温热水对还原炉的夹套、底盘及尾气进行冷却,加热后的热水进行闪蒸,年产6000 t的多晶硅规模,通过热量回收能产生0.3 MPa(g)的低压蒸汽44.77 t/h。达到节能降耗的目的,从而降低多晶硅生产的成本,以提高行业的竞争能力。     

多晶硅化学气相沉积数值模拟的研究进展

介绍了多晶硅气相沉积反应的几何模型和数学模型。回顾了。重点综述了近几年国内外还原炉内SHC13-H系统三维过程数值模拟的研究进展,并对其评述。讨论了化学气相沉积数值模拟的研究现状和存在的问题,展望了今后的发展方向。     

多晶硅还原炉内流场及温度场的研究

多晶硅还原炉（CVD reactor）是西门子法生产多晶硅的主要设备。硅在多晶硅还原炉（CVD reactor）内的生长是一个复杂的过程,涉及动量、热量、质量传递以及化学反应,炉内流体流动分布是影响还原能耗的关键因素。在这项研究中主要考虑如何提高还原炉中流场和温度场的均匀性。提出了一种新的还原炉设计方案,与传统的多晶硅还原炉相比,在新的还原炉内加入了内罩,从而形成了一种不同的气体流动方式。在新的还原炉内,气体进口和气体出口被划分到不同的区域,气体从气体进口进入CVD reactor后向上流动同时参与气相沉积反应,反应后通过内罩的顶部,最后从气体出口流出。研究重点是内罩结构的设计,以期可以提高还原炉内部流场及温度的均匀性。通过计算流体力学研究,现在水平方向上温度梯度很小,同时有效地减小了回流区域面积。本研究提供了提高多晶硅还原炉内部流场及温度场均匀性的方法。     

多晶硅还原炉硅棒直径检测及生长过程研究

还原炉是多晶硅生产的核心设备,在还原炉的运行控制中,硅棒直径是反应沉积效果的重要参数。笔者设计了一种硅棒直径检测方法,通过试用获得还原炉运行中硅棒直径检测数据,并综合各控制参数进行多晶硅棒生长过程的研究,其结论能够为还原炉运行优化提供参考依据。     

电子级多晶硅循环氢气深冷分离除杂技术研究

通过分析多晶硅还原炉尾气回收装置循环氢气中杂质的种类、来源、去除工艺,确定采取循环氢气深冷分离除杂技术解决磷化氢、砷化氢在氢气循环过程中的累积趋势,可以有效分离循环氢气中70％ 磷化氢和95％ 砷化氢,保证还原炉化学气相沉积过程中循环氢气的纯度.     

还原炉倒棒原因及改进措施研究

还原炉作为生产多晶硅的关键设备,生产多晶硅过程中常常出现倒棒现象,对还原炉产生严重损坏,重点针对硅棒沉积前期、中期、后期三个阶段倒棒的危害、原因进行分析,从还原炉喷嘴分布和大小、电极结构、石墨卡头结构、硅芯尺寸等方面进行改进,有利于降低还原炉硅棒倒棒率,提高生产效率,降低对还原炉设备的损坏.     

多晶硅还原加压工艺研究

为了降低多晶硅生产成本,对多晶硅生产中的重要环节———三氯氢硅(SiHCl3)还原生成多晶硅工艺进行了改进,将还原炉操作压力由常压提高至0.6 MPa,比较了加压工艺与常压工艺在多晶硅的沉积速度、沉积时间、还原反应耗电量以及多晶硅产品质量等指标上的区别。结果表明,还原炉压力由常压(0.1MPa)提高至0.6 MPa、H2和SiHCl3的量之比降低至3.5～5/1、SiHCl3和H2混合气的最大流量增加至2 000 kg/h、平均供气量约为980 kg/h时,多晶硅的沉积时间由200 h缩短至100 h;沉积速度由7～8 kg/h提高到20 kg/h,提高了150%以上;反应所需的单位耗电量也从135 kWh/kgSi降到75 kWh/kgSi,降幅达44%,从而大幅降低了多晶硅的生产成本;同时,产品质量也得到极大的提升。     

多晶硅还原炉接地故障预防措施

高纯三氯氢硅与氢气在还原炉内反应生成硅为改良西门子法生产多晶硅的关键步骤,还原炉运行情况对多晶硅的质量、产量及设备本体有极大的影响。接地故障是还原炉非正常停炉的常见原因。文章分析、总结接地故障发生的原因并提出相应预防措施。     

降低还原炉电单耗的措施

在改良西门子法生产多晶硅生产工艺中,还原炉是目前生产高纯多晶硅的主反应器。本文从还原炉运行时电量趋势、工艺控制参数以及异常停炉等方面,探讨了目前还原生产中影响还原电单耗的因素,对还原反应的过程及影响电耗的因素进行深入研究分析。     

多晶硅还原加压工艺研究

为了降低多晶硅生产成本，对多晶硅生产中的重要环节——三氯氢硅（SiHCl，）还原生成多晶硅工艺进行了改进，将还原炉操作压力由常压提高至0．6MPa，比较了加压工艺与常压工艺在多晶硅的沉积速度、沉积时间、还原反应耗电量以及多晶硅产品质量等指标上的区别。结果表明，还原炉压力由常压（0．1MPa）提高至0．6MPa、H2和SiHCl，的量之比降低至3．5—5／1、SiHCl，和H2混合气的最大流量增加至2000kg／h、平均供气量约为980kg／h时，多晶硅的沉积时间由200h缩短至100h：沉积速度由7～8kg／h提高到20kg／h，提高了150％以上；反应所需的单位耗电量也从135kWh／kgSi降到75kWh／kgSi，降幅达44％，从而大幅降低了多晶硅的生产成本；同时，产品质量也得到极大的提升。     

Chemical vapor deposition of silicon under reduced pressure in hot-wall reactors

A detailed mathematical model is discussed for low pressure, hot wall, chemical vapor deposition reactors. Although this model originates from previous studies on low pressure chemical vapor deposition (LPCVD) (Jensen and Graves, 1983), it includes two-dimensional diffusional mass transport between successive wafers, convective and diffusive mass transport in the annulus formed by the edges of the wafers and the reactor wall, and new overall reaction kinetics for the silicon depositing from silane. The system of the resulting coupled reactor equations is solved by finite difference methods.The chemical vapor deposition (CVD) of polysilicon from SiH₄ is studied in detail within the context of the model presented. Experimental data obtained in a LPCVD reactor operating in the electrical engineering department at Purdue University and other data reported in the literature compare very well with the predictions of the model discussed.     

Carbon nanostructures produced by CCVD with induction heating

The catalytic chemical vapor deposition (CCVD) method in which the outer furnace is replaced by the high frequency induction heating (IH) has been used for synthesis of carbon nanostructures. Using different catalysts, various types of carbon nanofibers were obtained, with the absence of the catalyst particles at their tip as a common characteristic. The IH mode combined with the CCVD method seems attractive for the synthesis of carbon nanostructures, allowing a significant decrease of energy consumption and of the overall reaction time as compared with the heating mode with outer furnace.     

流化床化学气相沉积多晶硅的技术进步与挑战

Various methods for production of polysilicon have been proposed for lowering the production cost and energy consumption, and enhancing productivity, which are critical for industrial applications. The fluidized bed chemical vapor deposition (FBCVD) method is a most promising alternative to conventional ones, but the homogeneous reaction of silane in FBCVD results in unwanted formation of fines, which will affect the product quality and output. There are some other problems, such as heating degeneration due to undesired polysilicon deposition on the walls of the reactor and the heater. This article mainly reviews the technological develop-ment on FBCVD of polycrystalline silicon and the research status for solving the above problems. It also identifies a number of chal-lenges to tackle and principles should be followed in the design of a FBCVD reactor.     

多晶硅的冷氢化工艺

对多晶硅的冷氢化闭合生产线进行了探讨,总结出一条低能耗、高产量的闭合循环生产线.主要包括如下几道工序:冷氢化,精馏,还原,还原尾气回收,歧化等.冷氢化工序进行冷氢化反应,主要包括固定床反应器、沉降器以及气提塔等设备.来自于气提塔的氯硅烷液体通过四级精馏塔进行分离,最后得到精制三氯氢硅.精制三氯氢硅进入还原系统生产多晶硅...     

碳化硼材料的制备技术

本文综述了国内外碳化硼粉末和碳化硼陶瓷制备技术的研究现状与进展情况,重点介绍了碳管炉、电弧炉碳热还原法、自蔓延高温合成法、激光诱导化学气相沉积法、溶胶凝胶碳热还原法合成碳化硼粉末以及热压、热等静压、无压烧结、放电等离子烧结和反应烧结制备碳化硼陶瓷的研究进展。     

铁矿微粉低温输送预还原及附碳行为

研究了铁矿微粉低温输送预还原中气固比、还原时间、炉温、矿粉粒径、还原剂种类等参数对矿粉还原率的影响,并运用正交设计和模式识别方法对工艺参数进行了优化,对预还原过程中样品的附碳行为进行了探讨. 结果表明,在矿粉粒径14~20 mm、炉温660~700℃、反应时间180~220 s、还原气成分CO 0~20%(j)的优化条件下,预还原率较高,最高达70.16%. XRD分析表明,还原样品发生碳吸附现象,少量氢气可提高碳吸附率.     

多晶硅制备工艺及发展趋势

简述了国内外多晶硅生产工艺的发展和现状,对比分析了各种多晶硅制备方法在产能、能耗及环境友好特性等方面的特点及其发展趋势。提出目前多晶硅制备技术主要有3个发展方向：①不断改进西门子工艺,包括尾气分离,四氯化硅氢化制备三氯氢硅,改进还原炉结构,加大炉体直径以提高产量、降低成本,三氯氢硅及氢气的纯化;②不断完善流态化技术方法,包括降低反应器内壁面上的硅沉积、减少无定形硅粉的形成、硅烷制备技术的改善;③不断完善冶金法工艺体系,包括提高产品纯度、减少杂质含量的波动性。     

多晶硅无定型硅粉形成原因及控制

改良西门子法多晶硅生产过程中,若还原过程控制不当,会产生影响产品品质及系统运行的无定型硅粉。通过对还原过程温度控制、物料配比、二氯二氢硅含量、炉筒水温、尾气管结硅及换热情况等多方面因素研究,分析了无定型硅粉形成原因,提出了相关控制措施。     

Selective formation of tungsten nanowires

We report on a process for fabricating self-aligned tungsten (W) nanowires with polycrystalline silicon core. Tungsten nanowires as thin as 10 nm were formed by utilizing polysilicon sidewall transfer technology followed by selective deposition of tungsten by chemical vapor deposition (CVD) using WF6 as the precursor. With selective CVD, the process is self-limiting whereby the tungsten formation is confined to the polysilicon regions; hence, the nanowires are formed without the need for lithography or for additional processing. The fabricated tungsten nanowires were observed to be perfectly aligned, showing 100% selectivity to polysilicon and can be made to be electrically isolated from one another. The electrical conductivity of the nanowires was characterized to determine the effect of its physical dimensions. The conductivity for the tungsten nanowires were found to be 40% higher when compared to doped polysilicon nanowires of similar dimensions.     

Formation of a Zinc Oxide/Yttria-Stabilized Zirconia Interface

Zinc oxide was deposited on the (111) face of an yttria-stabilized zirconia single crystal using the chemical vapor phase method. Zinc vapor was obtained by reducing polycrystalline ZnO in hydrogen at 1200°C. The deposition of the ZnO was accomplished by the reoxidation of zinc vapor at temperatures of 1300° to 1345°C.