CVD金刚石薄膜抛光技术的研究进展

采用化学气相沉积方法在非金刚石衬底上沉积的金刚石薄膜,本质上为多晶,而且表面粗糙。本文论述了目前国际上出现的抛光ＣＶＤ金刚石薄膜的主要方法,包括机械抛光法、热－化学抛光法、化学－＝机械抛光法、等离子体／离子束抛光法以及激光抛光法等。     

CVD金刚石膜高效超精密抛光技术

CVD金刚石膜作为光学透射窗口和新一代计算机芯片的材料,其表面必须得到高质量抛光,但是现存方法难以满足既高效又超精密的加工要求.本文提出机械抛光与化学机械抛光相结合的方法.首先,采用固结金刚石磨料抛光盘和游离金刚石磨料两种机械抛光方法对CVD金刚石膜进行粗加工,然后采用化学机械抛光的方法对CVD金刚石膜进行精加工.结果表明,采用游离磨料抛光时材料去除率远比固结磨料高,表面粗糙度最低达到42.2 nm.化学机械抛光方法在CVD金刚石膜的超精密抛光中表现出较大的优势,CVD金刚石膜的表面粗糙度为4.551 nm.     

用于MPCVD金刚石薄膜生长的高表面质量HTHP金刚石的制备

高质量的表面加工是金刚石体块和薄膜生长以及器件制备的关键.本实验利用激光切割块状HTHP金刚石,并采用激光共聚显微镜(LEXT)、拉曼光谱(Raman)及X射线光电子谱(XPS)、电子背散射衍射(EBSD)分析金刚石的表面形貌、抛光过程中表面状态的转化情况,以及抛光后金刚石的表面损伤及结晶质量.经过机械抛光和化学机械抛光,激光切割带来的表面碳化层和损伤层被有效去除,金刚石的表面粗糙度达到0.764 nm.进一步地,通过微波等离子体化学气相沉积(MPCVD)法在HTHP金刚石籽晶上沉积同质薄膜材料,获得生长条纹规则、低应力、拉曼半宽2.1 cm-1、XRD半宽仅为87arcsec的高质量金刚石薄膜.     

ECR等离子体刻蚀增强机械抛光CVD金刚石

采用电子回旋共振(ECR)等离子体刻蚀与机械抛光相结合的方法抛光化学气相沉积(CVD)金刚石,运用扫描电镜、Raman光谱观察、分析了刻蚀与抛光后金刚石的表面形貌和质量变化,并与单纯的机械抛光相比较,研究了等离子体刻蚀对后续机械抛光的影响,结果发现:金刚石经ECR等离子体刻蚀后非晶碳含量有一定程度降低,刻蚀过程在金刚石晶面形成的疏松表面有利于机械抛光,金刚石表面平均粗糙度更加快速降低。对比实验表明等离子体刻蚀对机械抛光前期的抛光效率的增强效果更为明显,在ECR等离子体刻蚀后的金刚石样品经10min机械抛光后粗糙度从7.284下降到1.054μm,而直接机械抛光30min时金刚石的表面粗糙度为1.133μm,在机械抛光的初始阶段,等离子体刻蚀后的机械抛光效率是单纯机械抛光效率的3倍。最终,经过三次重复刻蚀后机械抛光,金刚石表面粗糙度降为0.045μm。     

砷化镓衬底CVD金刚石薄膜辐射探测器的研究

在砷化镓（GaAs）衬底上采用微波等离子体化学气相沉积法（MPCVD）制备了金刚石薄膜,并对制备的薄膜进行抛光、表面氧化、退火等处理以提高薄膜质量,再用磁控溅射法在薄膜表面沉积金（Au）铝（Al）电极,制备了简易的CVD金刚石薄膜辐射探测器。采用扫描电子显微镜（SEM）和拉曼光谱（Raman）技术对制得的金刚石薄膜质量进行了分析研究。结果表明,薄膜为[100]晶面取向,表面平整,杂质含量低。采用5.9keV55FeX射线对所制备的探测器进行辐射实验,测出其光电流和暗电流特性,从而对辐射探测器性能进行了表征。     

复合抛光对 CVD金刚石薄膜表面光洁度的改进研究

采用激光抛光和热化学抛光相结合的方法，对通过热丝CVD方法生长的金刚石薄膜进行了复合抛光处理．并利用X射线衍射仪（XRD）、拉曼光谱仪（Raman）、扫描电子显微镜（SEM）和原子力显微镜（AFM）对金刚石薄膜进行了表征．结果表明，所合成的金刚石薄膜是高质量的多晶（111）取向膜；经复合抛光后，金刚石薄膜的结构没有因抛光而发生改变，金刚石薄膜的表面粗糙度明显降低，光洁度大幅度提高，表面粗糙度Ra在100nm左右，基本可以达到应用的要求．     

CVD金刚石薄膜摩擦学性能的研究现状

化学气相沉积(Chemical vapor deposition,CVD)金刚石薄膜通常是一种表面粗糙的多晶薄膜,其摩擦系数相对于光滑金刚石明显偏高,这制约着其在摩擦学领域的应用。在综合分析近年来该领域研究的基础上,总结了CVD金刚石薄膜摩擦学性能的主要影响因素,并从降低其摩擦系数的角度出发,着重讨论了几种提高CVD金刚石薄膜摩擦性能的途径。     

金刚石涂层激光抛光机理及加工工艺研究进展

CVD金刚石涂层表面粗糙度高、颗粒大,不能满足精密和超精密加工的要求,在一定程度上制约了其发展和应用,降低CVD金刚石涂层表面粗糙度是迫切需要解决的难题.阐述了激光抛光CVD金刚石涂层机理,对比了微观抛光和宏观抛光的差异,总结了国内外激光抛光金刚石涂层研究进展,探讨了 目前激光抛光金刚石涂层的挑战和亟待解决的难点.     

{100}织构化学气相沉积金刚石薄膜的取向生长过程

为了研究化学气相沉积（CVD）金刚石薄膜生长过程中{100}织构的形成机理,采用x射线衍射、电子背散射衍射和扫描电镜研究了CVD自支撑金刚石薄膜的宏观织构、微区晶界分布和表面形貌。结果表明：金刚石薄膜以{111}面或{100}面为生长前沿面都能够形成{100}织构,但形成的表面形貌不同;通过吸附CH3-和CH3-在{1...     

单晶金刚石机械研磨结合化学辅助机械抛光组合加工工艺

单晶金刚石因具有最高的硬度和最低的摩擦系数常被用来制备超精密刀具,而表面粗糙度是影响刀具寿命的重要指标.提出采用机械研磨结合化学辅助机械抛光的组合工艺抛光单晶金刚石.实验优化并确定的加工工艺如下:先用5μm和2μm金刚石粉研磨单晶金刚石表面,然后采用化学机械的方法去除机械研磨带来的损伤.用该工艺抛光单晶金刚石,表面粗糙度Ra可达0.8 nm(测量区域70μm×53μm).表面拉曼光谱分析表明化学机械抛光的表面只有1 332 cm-1拉曼峰.     

Investigation into polishing process of CVD diamond films

A new technique used for polishing chemical vapor deposition (CVD) diamond films has been investigated, by which rough polishing of the CVD diamond films can be achieved efficiently. A CVD diamond film is coated with a thin layer of electrically conductive material in advance, and then electro-discharge machining (EDM) is used to machine the coated surface. As a result, peaks on the surface of the diamond film are removed rapidly. During machining, graphitization of diamond enables the EDM process to continue. The single pulse discharge shows that the material of the coated layer evidently affects removal behavior of the CVD diamond films. Compared with the machining of ordinary metal materials, the process of EDM CVD diamond films possesses a quite different characteristic. The removal mechanism of the CVD diamond films is discussed.     

抛光对化学气相沉积金刚石自支撑膜断裂强度的影响

研究了抛光对化学气相沉积金刚石自支撑膜断裂强度的影响。结果表明,金刚石自支撑膜粗糙表面所带来的V形缺口会降低其断裂强度,而且随着膜厚的增加,降低的程度越明显,通过抛光粗糙表面,消除了V形缺口对断裂强度的影响,有利于提高金刚石膜的抗破坏能力。提出了一种金刚石膜断裂强度的经验计算方法,获得的断裂强度值更接近于金刚石膜的本征断裂强度。     

稀土化合物浆料对CVD金刚石厚膜的刻蚀

ＣＶＤ金刚石厚膜具有极高的硬度,使得对其进行表面抛光极为困难．传统的机械抛光方法既不经济又耗费时间,而一些新的抛光技术又由于实验条件限制而难以推广．针对以上情况,我们寻求到一种新的化学刻蚀方法,即利用稀土化合物浆料对金刚石厚膜生长表面进行刻蚀,破坏表面的晶粒使之成为晶骸,降低表面的耐磨性,以提高表面粗糙的金刚石厚膜的抛光效率．     

CVD金刚石厚膜的稀土化合物浆料刻蚀

与现有的金刚石膜势光工艺相匹配的高效刻蚀技术,是目前研究的热点,自行研制的稀土化合物浆料对CVD金刚石厚膜进行了刻蚀研究,刻蚀过程在低于金刚石氧化点的温度下和大气环境中完成,其刻蚀结果,用扫描电子显微镜给出。实验表明,该工艺采用廉价的稀土化合物为原料,具有简单、完全、高效的特点。     

Chemical/mechanical polishing of diamond films assisted by molten mixture of LiNO3 and KNO3

Chemical/mechanical polishing can be used to polish the rough surface of diamond films prepared by chemical vapor deposition (CVD). In this paper, a mixture of oxidizing agents (LiNO₃ + KNO₃) has been introduced to improve the material removal rate and the surface roughness in chemical/mechanical polishing because of its lower melting point. It had been shown that by using this mixture the surface roughness R_a (arithmetic average roughness) could be reduced from 8-17 to 0.4 μm in 3 h of polishing, and the material removal rate can reach 1.7-2.3 mg/cm²/h at the temperature of 623 K. Pure aluminium is compared with cast iron as the contact disk material in the polishing. Although the material removal rate of aluminiumdisk is lower than that of cast iron, it can eliminate the carbon contamination from the contact disk to the surface of diamond films, and facilitate the analysis of the status of diamond in the chemical/mechanical polishing. The surface character and material removal rate of diamond films under different polishing pressure and rotating speed have also been studied. Graphite and amorphous carbon were detected on the surface of polished diamond films by Raman spectroscopy. It has been found that the oxidization and graphitization combined with mechanical cracking account for the high material removal rate in chemical/mechanical polishing of diamond films.     

Polishing of polycrystalline diamond by hot nickel surface

A microwave plasma technique has been employed to deposit polycrystalline diamond film over a molybdenum substrate button using a gas mixture of hydrogen and methane at a substrate temperature of 851°C. A CVD diamond coated molybdenum substrate button was mounted with a load against hot nickel plate and rotated for 3.45 h in a hydrogen ambient. Hot tungsten filament was used as a heat source to maintain the temperature of the nickel block and CVD diamond coated molybdenum button at 848°C. This experiment has reproducibly shown the successful polishing of polycrystalline CVD diamond by hot nickel. A Tencor profilometer and scanning electron microscope have been used to evaluate the surface smoothness and morphology before and after polishing the polycrystalline diamond thin films.     

Fabrication of Boron-Doped CVD Diamond Microelectrodes

Diamond microelectrodes are fabricated using microwave plasma CVD for the growth of electrically conducting single microcrystallite diamonds as well as diamond films on etched tungsten wires which are subsequently sealed in glass. The electroactive diamond is exposed by either mechanical polishing or by chemical etching of the glass. The resulting microelectrodes yield steady-state cyclic voltammograms at low scan rates.     

Fabrication and Characterization of FeNiCr Matrix-TiC Composite for Polishing CVD Diamond Film

Dynamic friction polishing (DFP) is one of the most promising methods appropriate for polishing CVD diamond film with high efficiency and low cost.By this method CVD diamond film is polished through being simply pressed against a metal disc rotating at a high speed utilizing the thermochemical reaction occurring as a result of dynamic friction between them in the atmosphere.However, the relatively soft materials such as stainless steel, cast iron and nickel alloy widely used for polishing CVD diamond film are easy to wear and adhere to diamond film surface, which may further lead to low efficiency and poor polishing quality.In this paper, FeNiCr matrix-TiC composite used as grinding wheel for polishing CVD diamond film was obtained by combination of mechanical alloying (MA) and spark plasma sintering (SPS).The process of ball milling,composition, density, hardness, high-temperature oxidation resistance and wear resistance of the sintered piece were analyzed.The results show that TiC was introduced in MA-SPS process and had good combination with FeNiCr matrix and even distribution in the matrix.The density of composite can be improved by mechanical alloying.The FeNiCr matrix-TiC composite obtained at 1273 K was found to be superior to at 1173 K sintering in hardness, high-temperature oxidation resistance and wearability.These properties are more favorable than SUS304 for the preparation of high-performance grinding wheel for polishing CVD diamond film.