【作者】 万烨；

【导师】 肖劲；

【作者基本信息】 中南大学 ， 有色金属冶金， 2022， 博士

【摘要】 随着我国超大规模集成电路、平板显示等产业的迅速发展,高纯电子气体市场需求量快速增长,成为仅次于衬底材料的第二大半导体材料,其中高纯三氯氢硅（TCS）和二氯二氢硅（DCS）在外延、薄膜沉积等工艺广泛应用,是集成电路的关键电子特气,但是其制备技术被国外公司垄断,产品依赖进口。在改良西门子法多晶硅制造过程中,涉及到TCS、四氯化硅（STC）等多种中间产物和副产物,但其品质不能满足集成电路质量要求。论文从制约集成电路产业发展的瓶颈出发,以改良西门子法多晶硅制造的过程产物为研究对象,进行高纯TCS和DCS制备技术和工程化应用研究,同时进行产品延伸应用的探索,主要研究内容与结论如下:（1）综合运用流体动力学、分子动力学和DFT计算等手段进行甲基氯硅烷的分离研究。建立Si HCl₂CH₃-TCS-Cl·模型体系,使用气液法预测不同氯化因子下的TCS中甲基二氯硅烷（Si HCl₂CH₃）的氯化动力学过程,采用Standard k-εModel模型和多相流模型进行心型微通道反应器仿真模拟,速度矢量、速度云图分布和湍动能仿真结果表明,各反应模块的一致性较好。实验考察了不同因素对Si HCl₂CH₃含量的影响,确定了光氯化反应的最优条件:n（Cl₂）:n（Si HCl₂CH₃）=5:1,温度50℃,紫外光波长365 nm,光强15 W,时间为20 s,此条件下产品中Si HCl₂CH₃含量为5×10^-8g/g,去除率为99.67%。（2）采用Reax FF MD模拟和DFT计算对硅-氯-氢原子的反应选择性进行研究。结果表明,与TCS相比,尤其在低温下Cl·倾向于与Si HCl₂CH₃反应,且反应主要是Cl·取代H后与Si键合,在297 K至347 K温度区间内,在光催化氯化反应过程中,Cl₂不能与TCS或Si HCl₂CH₃分子直接反应,通过紫外光照射,Cl₂先分解为Cl·然后再参与反应。在与Si HCl₂CH₃反应中,Cl·取代H后与Si结合的△G是-52.4 k J·mol^-1。（3）采用GC-MS对多晶硅系统氯硅烷中硼、磷杂质的赋存状态进行定性分析研究,通过特征碎片进行绘图和对比,推测P杂质主要以POCl₃形态存在,B杂质主要以BCl₃形式存在。将含有氧、氮等孤对电子的试剂与杂质进行络合,结果显示,对于B指标的最佳因素是肉桂醛、40:1、时间8 h。对于P指标的最佳影响因素是苯甲醛、20:1、时间8 h。设计“脱重-脱轻-脱重”三塔精馏模型,T1～T3塔理论塔板数均为75,回流比为4、10和4,采出量是各自进料的0.05、0.16和0.05%（wt.%）,液泛因子均不超过85.00%。（4）以高纯TCS为原料歧化联合精馏制备DCS,选择弱碱性阴离子交换树脂为催化剂,催化剂用量为m（催化剂）/m（TCS）=0.2,60℃时,转化率达到19.00%。通过流体动力学计算,得出反应器经济床层厚度为3300 mm。采用DFTb MD模拟探索TCS的催化歧化反应的微观反应机理,模拟表明:TCS自身较难直接发生歧化反应。催化条件下,叔胺基的氮原子能与TCS的硅原子结合,促进出现氯自由基,造成氯硅烷分子聚集,对氯硅烷歧化反应有促进作用;多氯环境会影响催化剂与TCS的结合方式,加速催化剂的失效,造成歧化反应DCS的产率减少、STC的产率增加。设计DCS四塔精馏模型,T1～T4塔板数分别为50、45、60和50块,水力学计算结果四塔的液泛率分别为33.50%、56.50%、78.00%和54.00%。（5）进行实验室技术的工业化应用转化研究,提出络合反应、光催化反应和高效精馏工程方案并进行产业化应用,制备出纯度大于99.99%（GC）的高纯TCS。进一步以高纯TCS为原料,提出催化歧化反应和高效分离工程方案,制备出纯度大于99.99%（GC）的高纯DCS。通过第三方检测和对标,应用本技术制备的产品指标处于较好的水平,形成良好的示范效应。以制备的高纯DCS为原料,进行了BTBAS实验室合成的探索,依次进行合成、反应产物的粗蒸馏、旋转蒸馏和二次精馏,最终实验室纯化得到99.44%纯度的BTBAS。更多还原

【Abstract】 The demand for high purity electronic gas is driving much of the growth due to the booming development of industries such as very large scale integrated circuit（IC）and flat panel display.This kind of electronic gases segment held the second largest market share of semiconductor manufacturing materials.High purity Trichlorosilicon（TCS）,Dichlorosilane（DCS）are the critical raw materials and widely used in epitaxy,film deposition and other manufacturing processes of IC industry.However,the corresponding preparation technology has been monopolized by foreign companies,and the products are heavily dependent on imports.In the modified Siemens polysilicon manufacturing process,a variety of intermediates and by-products such as TCS and silicon tetrachlorosilane（STC）are formed.However,its quality cannot meet the quality requirements of IC.Starting from the bottleneck restricting the development of the IC industry,the paper takes the process products of the improved Siemens process polysilicon manufacturing as the research object,conducts research on the preparation technology and engineering application of high-purity TCS and DCS,and explores the extension application of products.The main research results are as follows:（1）The separation of methyl chlorosilane was studied by means of fluid dynamics,molecular dynamics and DFT calculation.The model system building of Si HCl₂CH₃-TCS-Cl·was studied.The chlorination kinetics process of methyl dichlorosilane in TCS with different chlorination factors was predicted by gas-liquid method.Meanwhile,the Standard k-εModel and multiphase flow model were used to simulate the heart-shaped micro-channel reactor to feedback the gas-liquid mixture distribution state.Good consistency of each reaction module was illustrated by the simulation results of velocity vector,velocity cloud distribution and turbulent kinetic energy through simulation calculation.The effects of different factors on the content of methyl dichlorosilane were also investigated.The optimal photochlorination reaction conditions were determined as follows:n（Cl₂）:n（Si HCl₂CH₃）=5:1,reaction temperature of 50°C,UV light wavelength of 365 nm,light intensity of15 W and reaction time of 20 s.The content of methyl dichlorosilane in the final product was 5×10^-8g/g with the removal rate of 99.67%.（2）Reax FF MD simulation and DFT calculation were used to study the reaction selectivity of silicon,chlorine and hydrogen atoms.The results showed that Cl·tended to react with Si HCl₂CH₃ to form Si-Cl bond by replacing H compared with Si HCl₃,especially at low temperature.In the temperature range of 297 K to 347 K,Cl₂ cannot react directly with Si HCl₃ or Si HCl₂CH₃ molecules in the process of photocatalytic chlorination until Cl₂ is decomposed into Cl·by UV irradiation.In this reaction,the△G of Si-Cl bond formation after the substitution of Cl·for H is-52.4 KJ·mol^-1.（3）The occurrence state of boron and phosphorus impurities in chlorosilane of polysilicon system was qualitatively analyzed by GC-MS.It is speculated that the P impurity mainly exists in the form of POCl₃,and the B impurity mainly exists in the form of BCl₃.Chemical reagents with functional groups containing oxygen,nitrogen and other lone pair of electrons were selected to perform the orthogonal experiment.The results showed that the main influence factors for the content of boron impurity were reaction time of 8 hours,mole ratio of 40:1 and using cinnamaldehyde as reaction reagent.Regarding phosphorus impurity,the optimal parameters were reaction time of 8 hours,mole ratio of 20:1 and using benzaldehyde as reaction reagent.The purification model of three distillation columns（T1-T3）with the theoretical plate number of 75 and the suitable reflux ratios were 4,10 and 4.The output mass fraction of T1～T3 columns with respect to input flow rate were 0.05wt.%,0.16wt.% and 0.05 wt.%respectively,and the flooding factor of a single plate was less than 85.00%.（4）DCS is prepared by disproportionation combined distillation with high-purity TCS as raw material,Weakly basic anion exchange resin was selected to investigate the disproportionation catalysts.When the ratio between m（catalyst）and m（TCS）was 0.2 and temperature was60℃,the disproportionation conversion rate of TCS reached 19.00%.Through the study of the fluid dynamics simulation of catalytic reactor,concluded that the reactor bed thickness was preferably 3300 mm.DFTb MD simulation was used to explore the microscopic reaction mechanism of catalytic disproportionation reaction of TCS.The simulation results show that TCS is difficult to directly perform disproportionation reaction without the influence of other molecules,and the reaction products are unstable and prone to reverse reaction.The nitrogen atom of the key tertiary amine group in the catalyst is combined with the silicon atom of TCS,and the chlorine radical is extruded,which can also induce the molecular aggregation of chlorosilane and promote the chlorosilane disproportionation reaction.The disproportionation of TCS observed in the simulation indicates that the disproportionation reaction of chlorosilane molecules may involve multiple molecules and proceed in steps continuously.The chlorine-rich environment will affect the combination mode of catalyst and TCSand accelerate the failure of the catalyst,which results in low yield of DCS and STC content increasing.Design four-column distillation system of DCS.The number of plates for T1-T4 purification columns were set at 50,45,60 and 50,respectively.The maximum flooding rates of T1～T4 were 33.50%,56.50%,78.00%and 54.00%.（5）The complexation reaction,photocatalytic reaction and high efficiency distillation engineering schemes were put forward and applied industrially,which realized to transform the laboratory technology to industrial application.The high purity TCS with concentration larger than99.99 wt.%（assay by GC）was prepared.Furthermore,the catalytic disproportionation reaction and high efficiency separation was demonstrated using high purity TCS as raw material.The high purity DCS with concentration larger than 99.99 wt.%（assay by GC）.The quality of products prepared by this technology are at an advanced level through third-party testing.The products have been widely used in relevant domestic enterprises.With the prepared high-purity DCS as raw material,the laboratory synthesis of BTBAS was explored.The synthesis,crude distillation of reaction products,rotary distillation and secondary distillation were carried out successively,and finally the BTBAS with99.44%purity was purified in the laboratory.更多还原