MPCVD装置基片台改进对金刚石薄膜均匀性的影响

通过对实验室自主研发的10 k W新型微波等离子体装置基片台的改进,获得了更高的基片温度,更长的保温时间以及更均匀的基片温度。用直径为80 mm的硅片在改进后的基片台上用MPCVD法沉积大面积金刚石膜。在微波功率为5 k W,沉积气压为5.6 k Pa环境下基片中心获得900℃的基片温度,沉积时间8 h。实验后对硅片中央区域,距离中心20 mm区域,距离基片中心35 mm区域进行对比分析,通过SEM显示三个区域金刚石膜的表面形貌差异很小,通过拉曼光谱观察到在1 332 cm-1处代表金刚石相的特征峰无明显的变化从而确定可金刚石膜在质量上的均匀性,最后对金刚石的厚度表征发现所观察的区域内膜厚变化保持在0.2⁰.4μm之间且金刚石呈现柱状生长模式。     

圆柱形单模MPCVD装置的数值模拟与实验研究

微波等离子体化学气相沉积（MPCVD）法因其独特的优势被认为是制备高质量金刚石膜的首选方法。本实验对圆柱形MPCVD装置谐振腔中的电场分布及强度进行了数值模拟,在此基础上,在自行研制的圆柱形单模MPCVD装置上,进行了等离子体放电和金刚石膜的制备。结果表明:在输入功率仅为100 W的情况下,自行研制的圆柱形单模MPCVD装置的基片上方模拟计算得到的最高电场强度可达3.0×105 V/m,即电场具有较好的聚焦能力,石英板式窗口的设计避免了等离子体的刻蚀。同时,在直径50mm硅片上进行了微米及纳米金刚石膜的生长研究,沉积出高质量金刚石膜。研究结果为MPCVD装置的研制提供了理论指导。      

基于内涨鼓泡实验的金刚石膜附着强度精确定量评价

根据内涨作用下薄膜发生鼓泡变形的原理，开发了1种新的适用于金刚石膜附着强度精确定量评价的测试系统。并在传统的硅平面加工工艺的基础上发展了1种新的在沉积好的基片上制备自支撑窗口试样的方法，该方法可以保证在刻蚀基底形成自支撑窗口的同时不会损坏到薄膜。通过实验，实现了对硅基底金刚石膜结合强度的定量检测，实验得到的薄膜结合强度为4．28726J／m^2。实验所测得的附着强度结果与有限元仿真结果类比的吻合，证实了该模型的有效性，从而为金刚石膜的制备工艺优化及其质量的评估提供了可靠的依据和标准，对促进金刚石膜材料的深度开发和工程应用将具有积极的意义。     

含氢掺硅类金刚石薄膜的制备及性能表征

采用磁控溅射和离子源复合沉积技术,在Si片、模具钢和硬质合金上制备了均匀致密的含氢掺硅类金刚石薄膜.先用正交法优化含氢类金刚石薄膜的制备工艺,然后通过控制中频碳化硅靶的功率密度向含氢类金刚石膜层中成功掺人Si元素.采用扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)、X射线衍射仪(XRD)、硬度计、划痕仪和摩擦磨损试验机等手段测试和研究了膜层的形貌、成分、sp3和sp2含量及其性能.结果表明:优化后含氢类金刚石薄膜的制备工艺为:30 mL/min甲烷流量,100 V偏压,0.8A离子源电流;所制备的含氢掺硅类金刚石薄膜是非晶结构,膜厚2.20 μm,膜、基结合力为30 N,膜层硬度达到2039 HV.含氢掺硅类金刚石薄膜的摩擦因数受环境湿度变化很小,可应用于精密传动部件提高其使用精度.     

纳米金刚石抛光液制备及应用

随着光电信息产业的迅猛发展,纳米金刚石抛光液成为了超精密抛光领域的研究热点.本文首先总结了国内外专家、学者关于纳米金刚石微粉在水性和油性介质中的分散方面的一些研究工作,对微粉在介质中的分散、稳定机理进行了初步的探讨;并对纳米金刚石抛光液的制备以及抛光液在半导体硅片、计算机硬盘基片、计算机磁头、光纤连接器以及其它材料的表面超精密抛光应用进行了综述.水基纳米金刚石抛光液可能是未来抛光液的发展方向.     

高等离子体功率密度下MPCVD法制备多晶金刚石膜

通过自制的MPCVD双基片台设备,在微波功率为1400 W保持不变及中高气压,等离子体功率密度为357.5～807.4 W/cm3,基片温度为850 ± 30 ℃,CH₄体积分数为1.0%～1.5%,沉积速率为1～8 μm/h条件下,在直径11.5 mm的硅基片上沉积不同质量的多晶金刚石膜,并通过光谱仪、光学显微镜、拉曼光谱仪对等离子体中的氢原子及含碳基团、多晶薄膜的形貌及质量进行表征。结果表明:随着等离子体功率密度上升,等离子体椭球中的氢原子基团和含C的活性基团强度增加,金刚石膜生长速率大幅度提高,金刚石膜纯度也大幅度提升。在气压为21 kPa,等离子体功率密度为807.4 W/cm3,基片温度为850±30 ℃,生长时间为150 h,CH₄体积分数为1.0%及氢气流量为200 mL/min的条件下,金刚石膜的生长速率达到5 μm/h,金刚石膜厚达752.0 μm,金刚石拉曼峰的半高宽为6.48 cm?1,且生长的金刚石膜质量良好。      

金刚石砂轮磨削贴膜硅片崩边的研究

用树脂结合剂金刚石砂轮将贴膜厚度为80 μm和160 μm的单晶硅片减薄到400 μm，通过测量硅片边缘的崩边尺寸评价贴膜对硅片加工质量的影响。试验结果表明:硅片贴膜能有效降低硅片碎片率；当硅片未贴膜时，硅片的平均崩边尺寸为3.08 μm，当硅片贴膜厚度为80 μm和160 μm时，硅片的平均崩边尺寸为4.61 μm和3.60 μm；即硅片贴膜磨削对硅片崩边有恶化作用，但该影响较小，用厚膜时恶化程度可控制在20%以内。且用23 μm金刚石砂轮减薄磨削贴膜硅片时，硅片<110>晶向和<100>晶向的崩边尺寸无明显差异。      

纳米金刚石膜真空窗口的制备

使用自制的微波等离子体化学气相沉积装置,以乙醇为碳源在（100）硅表面制备了金刚石膜;然后用浓硝酸和氢氟酸的混合溶液腐蚀硅,制备出金刚石膜窗口。使用场发射扫描电镜（SEM）、X射线衍射、拉曼光谱（Raman）、原子力显微镜（AFM）表征和分析金刚石膜,并以自制的漏气率测量系统测量金刚石膜窗口的漏气率。结果表明:金刚石膜的厚度为15 μm,平均粗糙度值R_a为39.5 nm,晶粒的尺寸大小为30 nm,漏气率为8.8×10-9 Pa·m3/s。      

过滤式阴极电弧沉积类金刚石薄膜的性能分析

成功地研制了一套过滤式阴极电弧沉积设备,并利用该设备成功获得了类金刚石薄膜。类金刚石薄膜的扫描电镜分析表明：获得的薄膜在硅基片上是光滑和致密的,在Ｔｉ合金基片上有裂纹,高速钢基片上有微孔。原子力显微镜分析表明：膜层的表面粗糙度与沉积参数密切相关。喇曼光谱研究表明,这种薄膜是典型的无氢类金刚石薄膜,喇曼光谱的高斯分解表明：随着偏压的变化,Ｄ线和Ｇ线的位置μＤ、μＧ向低频移动,半高宽σＤ减小。     

过滤式阴极电弧沉积类金刚石薄膜工艺的研究

本文研究了过滤式阴极电弧沉积系统的稳弧工艺参数,通过正交试验获得最佳稳弧参数,并且研究了弯管内置挡板对宏观粒子过滤效果的影响,采用喇曼光谱研究了偏压对生成的类金刚石薄膜性能的影响,证明－１００Ｖ偏压下,获得的类金刚石薄膜有最佳的ｓｐ＾３含量,扫描电镜测试表明,在（１１１）硅基片上获得致密的膜,但在高速钢基体上沉膜堆积现象比较严重,不易获得优质类金刚石膜。     

梯度基体温度法和反应溅射TiC过渡层对钛合金基体沉积金刚石薄膜的影响

以H2和CH4作为反应气体,采用热丝化学气相沉积法(HFCVD)在钛合金(Ti6Al4V)平板基体上制备金刚石薄膜,利用扫描电镜(SEM)、X射线衍射仪(XRD)、激光拉曼光谱(Raman)和洛氏硬度仪分析薄膜的表面形貌、结构、成分和附着性能,研究了高温形核-低温生长的梯度降温法对原始钛合金和反应磁控溅射TiC过渡层的钛合金表面沉积金刚石薄膜的影响。结果表明:原始基体区和TiC过渡层区沉积的金刚石薄膜平均尺寸分别为0.77μm和0.75μm,薄膜内应力分别为-5.85GPa和-4.14GPa,TiC层的引入可以有效提高金刚石的形核密度和晶粒尺寸的均匀性,并减少薄膜残余应力;高温形核-低温生长的梯度降温法可以有效提高金刚石的形核密度和质量,并提高原始基体上沉积金刚石薄膜的附着性能。     

硬质合金金刚石涂层的附着性能

将表面低Co含量(Co含量≈0.38wt%)的硬质合金基体在微波等离子体化学气相沉积装置中进行金刚石涂层,用扫描电镜(SEM)对金刚石涂层进行形貌分析,用EDAX确定硬质合金表面Co的含量,用压痕法和划痕法评价金刚石涂层与基体间的附着性。研究结果表明:不同厚度的金刚石涂层均具有良好的晶型。虽然涂层厚度增加,但是基体表面Co含量较少,是形成涂层/基体附着性能良好的主要原因,6μm的金刚石涂层具有较好附着性能。     

Growth of Free-standing Diamond Films on Graphite Substrates with Ti Interlayers

DIAMOND has many remarkable chemical andphysical properties,such as extreme hardness,highthermal conductivity,high electrical resistively andexcellent optical transparency and so on.For diamond,approximately5.5ev is required to excite an electronfrom the valence band to the conduction band,compared with1.1ev for Si and0.7ev for Ge m.Therefore,Diamond is a wide band gap material.Furthermore,due to the high vibration energy of carbonatoms in diamond,the frequency of infrared absorptionis abn…     

大面积金刚石膜/Si衬底复合片均匀性研究

对直流电弧等离子体喷射化学气相沉积技术,在φ76.2 mm的Si衬底上沉积得到的金刚石膜,通过SEM和激光Raman表征其质量均匀性。为缓解金刚石膜/Si复合片的内应力,采用台阶式冷却的方式,对样品在1 050℃进行真空退火处理,使样品内的压应力从3.09 GPa减小到1.16 GPa。对样品生长面进行机械抛光,采用表面轮廓仪检测其表面粗糙度均匀性。结果表明：在76.2 mm的金刚石膜/Si复合片上获得的表面粗糙度小于5 nm。     

Mechanism and prediction of failure of diamond films deposited on various substrates by HFCVD

Diamond films were deposited on the WC-Co cemented carbide and Si3N4 ceramic cutting tool substrates by hot-filament-assisted chemical vapour deposition. The adherence property of diamond films was estimated using the critical load (Pcr) in the indentation test. The adhesive strength of diamond films is related to the intermediate layer between the film and the substrate. Poor adhesion of diamond films to polished cemented carbide substrate is owing to the formation of graphite phase in the interface. The adhesion of diamond films deposited on acid etched cemented carbide substrate is improved, and the peeling-off of the films often happens in the loosen layer of WC particles where the cobalt element is nearly removed. The diamond films' adhesion to cemented carbide substrate whose surface layer is decarbonizated is strengthened dramatically because WC phase forms by reaction between the deposited carbon and tungsten in the surface layer of substrates during the deposition of diamond, which results in chemical combination in the film-substrate interface. The adhesion of diamond films to silicon nitride substrate is the firmest due to the formation of chemical combination of the SiC intermediate layer in the interfaces. In the piston-turning application, the diamond-coated Si3N4 ceramic and the cemented carbide cutting tools usually fail in the form of collapsing of edge and cracking or flaking respectively. They have no built-up edge(BUE) as long as coating is intact.As it wears through, BUE develops and the cutting force on it increases 1 - 3 times than that prior to failure. This can predict the failure of diamond-coated cutting tools.     

MPCVD制备大颗粒金刚石形貌的研究

利用自制5 kW微波等离子体化学气相沉积(MPCVD)装置,沉积得到了晶粒尺寸达到500μm的大颗粒金刚石。采用抛光后的硅作为基底,CH4和H2为气源,分别研究了基片边缘与中心区域沉积的大颗粒金刚石的表面形貌。通过SEM表征了金刚石的表面形貌,发现基片边缘由于产生放电现象加速了金刚石的沉积,而晶粒之间相互挤压导致了孪晶的产生,影响其生长质量。相反由于中心区域形核密度低,使得晶粒在优先生长的模型下抑制了小晶粒的生长,从而提供更多的能量促进大晶粒的生长,在本实验条件下(100)晶面得到了长大,并获得了表面平整、晶体形貌良好的大颗粒金刚石。最后介绍了国内外合成大颗粒金刚石的研究进展,并对其研究方向做出了展望。     

DLC and UHMWPE as hard/soft composite film on Si for improved tribological performance

The main purpose of this study is to explore the advantages of using a composite thin film of ultra high molecular weight polyethylene (UHMWPE) on a hard diamond like carbon (DLC) coating deposited on Si, for high wear life and low coefficient of friction. The experiments are carried out using a ball-on-disc tribometer at a constant linear speed of 0.052 m/s. A 4 mm diameter silicon nitride ball with a normal load of 40 mN is used as the counterface. The tribological results are discussed on the basis of hardness, elastic modulus, contact area, contact pressure and optical images of surface films. As a result of higher load carrying capacity (high hardness and elastic modulus), the wear life of Si/DLC/UHMWPE coated layer is approximately five times greater than that of Si/UHMWPE. Looking at the film thickness effect, UHMWPE film shows maximum wear resistance when the film is of optimum thickness (6.2 μm-12.3 μm) on DLC. Wear mechanisms of different UHMWPE thicknesses for Si/DLC/UHMWPE film are explained using optical microscopy of worn surfaces. Further, the use of perfluoropolyether (PFPE) ultra-thin film as the top layer on the composite coatings reduces the coefficient of friction to very low values (0.06-0.07) and increases the wear life of the films by several folds.     

Critical parameters in hot filament chemical vapor deposition of diamond films on tool steel substrates with CrN interlayers

The accomplishment of adherent and continuous diamond coatings on tool steel substrates with CrN interlayers is determined by many key parameters such as appropriate surface finish, interlayer thickness, substrate temperature and system pressure. A detailed study is carried out to probe the effect of these parameters on diamond nucleation and growth. Substrates with different surface finishes are prepared by electrical discharge machining (EDM) and CrN interlayers of various thicknesses are deposited onto these substrates by arc plating. Samples with a CrN interlayer of 2.5 μm are found to provide a continuous diamond film at a low pressure value of about 5 mbar. Nonetheless, the process window for obtaining such diamond layers is small, which results in limited reproducibility.     

SiC基底HFCVD金刚石薄膜摩擦磨损性能

利用热丝化学气相沉积技术在碳化硅基底上制备微米金刚石薄膜、纳米金刚石薄膜和金刚石–石墨复合薄膜,采用扫描电子显微镜、原子力显微镜和拉曼光谱仪对不同金刚石薄膜的表面形貌和微观结构进行表征,通过摩擦磨损实验测试金刚石薄膜的摩擦系数并计算其磨损率,对比研究不同种类金刚石薄膜的摩擦磨损性能。结果表明:金刚石–石墨复合薄膜具有较好的摩擦磨损性能,薄膜表面粗糙度为53.8 nm,摩擦系数为0.040,和纳米金刚石薄膜（0.037）相当;金刚石–石墨复合薄膜的磨损率最低,为2.07×10?7 mm3·N?1·m?1。在相同实验条件下,同碳化硅基底的磨损率（9.89×10?5 mm3·N?1·m?1）和摩擦系数（0.580）相比,所有金刚石薄膜的磨损率和摩擦系数均有明显提升,说明在SiC基体表面沉积金刚石薄膜能够显著提高碳化硅材料在摩擦学领域的使役性能。