CVD法氮化硅薄膜制备及性能

氮化硅薄膜是一种重要的薄膜材料,具有优秀的光电性能,钝化性能和机械性能,将在微电子,光电和材料表面改性领域获得广泛应用,本文着重评述了制备氮化硅薄膜的几种化学相沉积方法和一些性能。     

氮化硅薄膜制备方法现状综述

氮化硅薄膜是一种多功能材料，在许多领域有着广泛的应用。本文系统综述氮化硅薄膜的性质、结构、应用及各种制备方法，并对今后的研究作了展望。     

PECVD制备富硅氮化硅薄膜的工艺条件及其性质的研究

采用等离子体增强化学气相沉积法(PECVD)以SiH4和N2为反应气体,分别在射频功率、硅烷稀释度[SiH4/N2]、衬底温度为变量的情况下制备了富硅氮化硅薄膜材料,利用X射线衍射谱(XRD)、傅里叶变换红外谱(FTIR)、紫外-可见光吸收谱(UV-Vis)对薄膜材料进行了表征,并研究了薄膜材料的微结构和晶化状况、光学特性等.实验结果表明,所沉积薄膜都为富硅的非晶氮化硅材料,改变射频功率、硅烷稀释度和衬底温度可以控制氮化硅薄膜中N元素的含量、光学带隙的大小和薄膜的折射率,并制备出最适宜富硅氮化硅薄膜,为进一步退火析出硅量子点奠定了基础.     

氮化硅薄膜的热丝化学气相沉积法制备及微结构研究

采用热丝化学气相沉积法,以Sill4、NH3、N2为反应气源,通过改变氮气流量沉积氮化硅薄膜.通过紫外-可见(UV-VIS)光吸收谱、傅里叶红外透射光谱(FTIR)、X射线衍射谱(XRD)等测试手段对薄膜的光学带隙、键合特性及晶相进行表征与分析.结果表明:薄膜主要表现为Si-N键合结构,当N2流量从20 sccm变化到40 sccm时,热丝能够充分的分解N2,薄膜中N原子过量,其周围的Si和H能充分的与N结合.但由于N2的解离能较高,当N2流量高于40 sccm时,氮气在反应过程中对薄膜内的氮原子反而起到了稀释作用,薄膜的有序程度增大,光学带隙减小,致密性降低.当氮气流量达到150 sccm时,在2θ为69.5°处出现了晶化β-Si3 N4的尖锐衍射峰,其择优取向沿(322)晶向,且Si3 N4晶粒显著增大.因此,氮气流量对薄膜中的氮含量有显著影响,适当的增加氮气流量有利于制备出优质含有小晶粒β-Si3 N4薄膜.     

高频等离子体化学气相沉积法制氮化硅超细粉的工艺研究

以Ar气为载气，SiCl4和NH3为原料，在高频等离子体化学气相沉积反应器中，制备了超细无定形的Si3N4粉未．该粉具有粒度小、粒径窄和分散均匀的特点，氮含量在36％以上．实验中发现，当SiCl4进料口在前，NH3进料口在后，且两个进料口均在高频等离子体尾焰处，经脱NH4Cl的产物中氮含量较高．而反应物NH3也不宜太过量，以NH3：SiCl4=8：1为好．Si3N4的晶型转变在1400“C下处理8h，效果较好     

常压CVD法制备氮氧化硅薄膜沉积特性的研究

采用常压化学气相沉积方法(atmospheric pressure chemical vapor deposition,APCVD)制备了氮氧化硅(Si—O—N)薄膜,研究了影响其沉积速率和生长模式的因素。在φ(NH_3):φ(SiH_4)=20:1,基板温度为650℃的条件下,当混合气体流量小于720ml/min时,薄膜的形成主要受气体扩散过程控制;当混合气体流量大于720 ml/min时,则主要受表面气相反应过程控制;混合气体流量为720 ml/min的条件下,氮氧化硅薄膜的沉积过程主要受基板表面的气相反应过程控制,薄膜沉积厚度与沉积时间成线性关系,反应速率为常数1640 nm/min,表面活化能为283 kJ/mol。通过SEM分析发现:氮氧化硅薄膜的形成方式符合三维成核模型,即反应初期Si,N,O等原子在基板表面相遇结合在一起形成原子团,一定数量的原子团构成临界核;反应中期临界核长大为岛状结构,岛不断长大,岛与岛之间相互接合形成通道网络结构;反应后期,原子不断填补网络空洞,最后成为连续薄膜。     

医用不锈钢表面沉积类金刚石薄膜的电化学腐蚀性能研究

医用316L不锈钢植入物植入体内后,体内环境可导致其产生腐蚀和Ni离子的析出。利用双放电腔微波等离子体源全方位离子注入设备,采用等离子体源离子注入(plasmasourceionimplantation,PSII)和等离子体增强化学气相沉积(plasmaenhancedchemicalvapordeposi tion,PECVD)复合工艺在医用316L不锈钢表面沉积类金刚石薄膜,进行表面改性,以提高其在模拟体液环境中的腐蚀阻抗。扫描电子显微镜和原子力显微镜观察发现,薄膜由纳米粒子构成,膜层连续光滑。电化学腐蚀测试表明:采用PSII+PECVD复合工艺制备的类金刚石薄膜与316L不锈钢改性体系在(37±1)℃的Troyde’s模拟体液中的自腐蚀电位约为120mV,体系的击穿电位超过1.9V,与基体316L不锈钢相比,其热力学稳定性与抗腐蚀性能得到增强,改性效果优于单独的PECVD工艺。     

a—C：H（N）类金刚石薄膜的结构及内应力分析

采用射频等离子增强化学气相沉积法制备出a－C：H（N）类金刚石薄膜，用X射线光电子能普、红外吸收光谱和慢正电子湮灭谱研究了薄膜的结构，用弯曲法测定了薄膜的内应力。随着混合气体中N2的含量从0增加到75％，薄膜中N量可增加到9．09％（摩尔分数），N原子与C原子以C－N，C＝N和C≡N键的形式结合，薄膜中的缺陷密度随含N量而增加，而薄膜的内应力则随着薄膜中N含量的增加而单调降低。     

a-C∶H(N)类金刚石薄膜的结构及内应力分析

采用射频等离子增强化学气相沉积法制备出a-C∶H(N)类金刚石薄膜, 用X射线光电子能谱、红外吸收谱和慢正电子湮灭谱研究了薄膜的结构, 用弯曲法测定了薄膜的内应力. 随着混合气体中N2的含量从0增加到75%, 薄膜中含N量可增加到9.09%(摩尔分数), N原子与C 原子以―C-N, CN和C≡N键的形式结合. 薄膜中的缺陷密度随含N量而增加, 而薄膜的内应力则随着薄膜中N含量的增加而单调降低.     

化学气相沉积氮化钛薄膜的研究

氮化钛薄膜材料具有优良的性能,应用广阔,总结了化学气相沉积制备氮化钛薄膜的方法和原理,介绍了化学气相沉积在制备氮化钛方面的应用现状和研究成果,分析了各种化学气相沉积方法的优势。     

Oxidation of Chemically-Vapor-Deposited Silicon Nitride and Slnglem-Crystal Silicon

Oxidation of {111} single-crystal silicon and dense, chemically-vapor-deposited silicon nitride was done in clean silica tubes at temperatures of 1000° to woo°C. The oxidation rates of silicon nitride under various atmospheres (dry O₂, wet O₂, wet inert gas, and steam) were several orders of magnitude slower than those of silicon under the identical conditions. The activation energy for the oxidation of silicon nitride decreased from 330 to 259 kJ/mol in going from dry O₂ to steam while that for Si decreased from 120 to 94 kJ/mol. The parabolic rate constant for Si increased linearly as the water vapor pressure increased. However, the parabolic rate constant for silicon nitride showed nonlinear dependency on the water vapor pressure in the presence of oxygen. The oxidation kinetics of silicon nitride is explained by the formation of nitrogen compounds (NO and NH₃) at the reaction interface and the counterpermeation of these reaction products.     

Surface Pretreatments of Silicon Nitride for CVD Diamond Deposition

The efficiency of different surface pretreatments (four standard chemical etchings and four diamond powder abrasive procedures) on silicon nitride (Si₃N₄) substrates for chemical vapor deposition (CVD) of diamond has been systematically investigated. Blank Si₃N₄ samples were polished with colloidal silica (∼0.25 μm). Diamond nucleation and growth runs were conducted in a microwave plasma chemical vapor deposition apparatus for 10 min and 6 h, respectively. Superior results concerning nucleation density ( N _d∼ 10¹⁰ cm⁻² after 10 min), film uniformity, and grain size (below 2 μm after 6 h) were obtained for the mechanically microflawed samples, revealing that chemical etchings (hot and cold strong acids, molten base or CF₄ plasma) are not crucial for good CVD diamond quality on Si₃N₄.     

等离子体增强化学气相沉积法制备氢化硅膜的自晶化倾向性

为了探寻生长过程中硅膜的自晶化沉积,采用等离子体增强化学气相沉积(PECVD)法沉积了氢化硅薄膜,系统研究了不同沉积阶段所得硅膜微观结构的迁变规律。结果表明,硅膜的显微结构依赖于沉积时间,当沉积时间仅为30min时,所得硅膜的结构为非晶;而当沉积时间延至60min时,硅膜形成微晶颗粒;此后随着沉积时间的增加,晶化程度提高,且非晶区域面积相应减小。另外,硅膜的沉积速率也随沉积时间的增加而增加。在硅膜沉积过程中,随时间不断变化的界面状态可能为其自晶化的主要原因。     

Low-Temperature Metal-Organic Chemical Vapor Deposition of Silicon Nitride

Amorphous silicon nitride films have been deposited on single-crystal silicon from the gas mixture of methylsilazane and ammonia at 873 to 1073 K. The films have been characterized by ellipsometry, Fourier transform infrared spectroscopy, and Auger electron spectroscopy. The Si-C, Si-H, and C-H bonds in methylsilazane can be effectively cleaved and the associated C and H species removed. The structure and composition of the films do not show any apparent dependence on the deposition temperature.     

Thermodynamic Calculations on the Chemical Vapor Deposition of Silicon Nitride and Silicon from Silane and Chlorinated Silanes

After a discussion of the thermochemical values of the Si–H–Cl–N system which occur in the literature, CVD phase diagrams are presented which include contours of constant deposition efficiency. The temperature range considered is from 800 to 2600 K. A number of chlorinated silanes as well as silane can be used as a silicon source, while ammonia is used as the nitrogen source. The effects of pressure variation and dilution by nitrogen and hydrogen are also included. Some initial calculations concerning silicon diimide are made. The CVD phase diagrams are used to describe several mechanisms occurring during the formation of silicon nitride from the gas phase.     

多孔石英基体上CVD法沉积氮化硅涂层的工艺、结构与性能研究

以甲硅烷(20％甲硅烷+80％氢气)和氨气作为反应前驱体,选择孔隙率为20％左右的多孔石英陶瓷基体,采用CVD法在多孔石英基体表面制备了氮化硅涂层.研究了沉积反应温度、反应压力、反应气体配比以及沉积时间等工艺参数对附着力的影响,确定了CVD法制备氮化硅涂层的最佳工艺参数,通过对所得涂层及复合材料进行抗弯强度和介电性能的表征,探讨了氮化硅涂层对多孔石英基体力学性能和介电性能的影响.     

Optimization of Chemical Vapor Deposition Parameters for Fabrication of Oxidation-Resistant Mullite Coatings on Silicon Nitride

Fabrication of mullite (3Al₂O₃·2SiO₂) coatings by chemical vapor deposition (CVD) using AlCl₃–SiCl₄–H₂–CO₂ gas mixtures was studied. The resultant CVD mullite coating microstructures were sensitive to gas-phase composition and deposition temperature. Chemical thermodynamic calculations performed on the AlCl₃–SiCl₄–H₂–CO₂ system were used to predict an equilibrium CVD phase diagram. Results from the thermodynamic analysis, process optimization, and effects of various process parameters on coating morphology are discussed. Dense, adherent crystalline CVD mullite coatings ∼2 μm thick were successfully grown on Si₃N₄ substrates at 1000°C and 10.7 kPa total pressure. The resultant coatings were 001 textured and contained well-faceted grains ∼0.3–0.5 μm in size.     

Preparation of Ultrafine Silicon Nitride, and Silicon Nitride and Silicon Carbide Mixed Powders in a Hybrid Plasma

Ultrafine Si₃N₄ and Si₃N₄+ SiC mixed powders were synthesized through thermal plasma chemical vapor deposition (CVD) using a hybrid plasma which was characterized by the superposition of a radio-frequency plasma and an arc jet. The reactant, SiCl₄, was injected into an arc jet and completely decomposed in a hybrid plasma, and the second reactant, CH₄ and/or NH₃, was injected into the tail flame through multistage ring slits. In the case of ultrafine Si₃N₄ powder synthesis, reaction effieciency increased significantly by multistage injection compared to single-stage injection. The most striking result is that amorphous Si₃N₄ with a nitrogen content of about 37 wt% and a particle size of 10 to 30 nm could be prepared successfully even at the theoretical NH₃/SiCl₄ molar ratio of ∼ 1.33, although the crystallinity depended on the NH₃/SiCl₄ molar ratio and the injection method. For the preparation of Si₃N₄+ SiC mixed powders, the N/C composition ratio and particle size could be controlled not only by regulating the flow rate of the NH₃ and CH₄ reactant gases and the H₂ quenching gas, but also by adjusting the reaction space. The results of this study provide sufficient evidence to suggest that multistage injection is very effective for regulating the condensation process of fine particles in a plasma tail flame.