微波等离子体化学气相沉积技术制备金刚石薄膜的研究

介绍了微波等离子体化学气相沉积法（MPCVD）制备金刚石薄膜的研究情况，重点论述了该法的制备工艺对金刚石薄膜质量的影响及其制备金刚石薄膜的应用前景。     

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。     

甲烷浓度对金刚石薄膜质量的影响

纳米金刚石薄膜具有优异的性能,已在多个领域获得广泛应用.但微波等离子体化学气相沉积制备的金刚石薄膜质量却严重受沉积工艺的影响,为了深入了解沉积工艺对制备的金刚石薄膜质量的影响,本文详细研究了甲烷浓度对微波等离子体化学气相沉积( MPCVD)金刚石薄膜质量的影响,利用扫描电镜、X射线衍射、拉曼光谱以及原子力显微镜对其进行...     

系统压强对微波等离子体化学气相沉积金刚石成核的影响

为了在氧化铝上制备（100）定向织构的金刚石薄膜,必须先提高金刚石的成核密度,在微波等离子体化学气相沉积（MPCVD）系统中,采用低压成核的方法,在氧化铝陶瓷上沉积出高成核密度的金刚石薄膜,扫描电镜显示其成核密度可达10^8cm^-2。在此基础上,沉积出（100）织构的金刚石薄膜。     

基片位置对MWPCVD制备金刚石薄膜的影响

在石英钟罩式微波等离子体化学气相沉积实验装置中研究了基片位置对金刚石薄膜沉积质量的影响。扫描电子显微镜显微形貌观察和激光喇曼谱分析表明 ,对微波等离子体化学气相沉积制备金刚石薄膜而言 ,基片位置处于近等离子体球下游区域将有利于改善金刚石薄膜沉积质量。     

通过制备Ti/TiC和Si/SixNy过渡层在铜基体上沉积类金刚石膜的研究

将磁控溅射物理气相沉积（MS-PVD）和电子回旋共振-微波等离子体增强化学气相沉积（ECR—PECVD）技术相结合，在铜基体上通过制备两种不同的过渡层，成功地沉积了类金刚石膜。拉曼光谱结果分析表明，所制备的碳膜都具有典型的类金刚石结构特征。通过原子力显微镜对薄膜的微观形貌进行分析，采用纳米压痕测量薄膜的硬度和模量。并对Ti／TiC过渡层和Si／SixNy过渡层上沉积的类金刚石薄膜进行了研究对比。     

基片位置对MWPCVD制备金刚石薄膜的影响

在石英钟罩式微波等离子体化学气相沉积实验装置中研究了基片位置对金刚石薄膜沉积质量的影响。扫描电子显微镜显微形貌观察和激光喇曼谱分析表明，对微波等离子体化学气相沉积制备金刚石薄膜而言，基片位置处于近等离子体球下游区域将有利于改善金刚石薄膜沉积质量。     

WC-Co硬质合金基体上高附着力金刚石薄膜的制备

采用微波等离子体化学气相沉积(CVD)法在WC-Co硬质合金基体上制备金刚石膜, 研究了TiN_x中间层的引入对金刚石薄膜质量及其附着性能的影响. 结果表明, 在酸浸蚀脱钴处理的基础上, 通过预沉积氮含量呈梯度变化的TiN_x中间过渡层, 可在硬质合金基体上制备出高质量的金刚石薄膜; 压痕法测试其临界载荷达1000N.     

化学气相沉积法制备超纳米金刚石薄膜

采用微波等离子体化学气相沉积法,利用CH4、SiO2和Ar的混合气体在单晶硅片基底上制备出高质量的超纳米金刚石薄膜.表征结果显示,制备的薄膜致密而均匀,晶粒平均尺寸约7.47nm,表面粗糙度约15.72nm,并且其金刚石相的物相纯度相对较高,是质量优异的超纳米金刚石薄膜材料.     

采用MPCVD法在硅衬底上选择性生长金刚石膜

采用微波等离子体化学气相沉积（MPCVD）法在附有SiO2掩摸的硅衬底上选择性沉积出了金刚石膜。采用扫描电子显微镜（SEM）和Raman光谱仪对金刚石膜的表面形貌和结构进行了表征。并讨论了衬底温度对金刚石薄膜选择性沉积的影响。得出了较佳的沉积条件。     

Novel heat spreader coatings for high power electronic devices

A new set of heat spreader coatings consisting of multilayers of diamond/AlN/diamond were deposited on high heat capacity substrates of molybdenum and silicon nitride. Bonding of the heat spreaders to the device wafers using gold-tin eutectic solder was carried out after metallization layers of titanium, gold and copper were deposited on diamond. Prior to bonding, backside of the silicon wafers was also metallized with titanium, gold and copper and the gallium arsenide wafers with titanium, copper-germanium alloy and gold. Characterization of the multilayer diamond films was carried out by Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The bonded wafers were tested for adhesion strength, resistance against peeling due to thermal cycling and failure under stress. Further, the bonded regions were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray mapping of different elements. The heat spreader characteristics of the single layer diamond and the multilayer diamond substrates were tested by infrared imaging. The results illustrate that the multilayer diamond heat spreader coatings provide better heat dissipation and also possess better adhesion strength and resistance against peeling under thermal cycling. These novel multilayer diamond/AlN/diamond heat spreaders are expected to considerably improve the life of high frequency power devices.     

Thermal conductivity of CVD diamond films

Diamond films 60 and 170 µm in thickness were grown by PACVD (plasma-assisted chemical vapor deposition) under similar conditions. The thermal diffusivity of these freestanding films was measured between 100 and 300 K using AC calorimetry. Radiation heat loss from the surface was estimated by analyzing both the amplitude and the phase shift of a lock-in amplifier signal. Thermal conductivity was calculated using the specific heat data of natural diamond. At room temperature, the thermal conductivity of the 60 and 170 m films is 9 and 16 W-cm^–1. K^–1 respectively, which is 40–70% that of natural diamond, The temperature dependence of thermal conductivity of the CVD diamond films is similar to that of natural diamond, Phonon scattering processes are considered using the Debye model, The microsize of the grain boundary has a significant effect on the mean free path of phonons at low temperatures. The grain in CVD diamond film is grown as a columnar structure, Thus, the thicker film has the larger mean grain size and the higher thermal conductivity. Scanning electron microscopy (SEM) and Raman spectroscopy were used to study the microstructure of the CVD diamond films. In this experiment, we evaluated the quality of CVD diamond film of the whole sample by measuring the thermal conductivity.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

CVD金刚石薄膜热,导率的研究

研究了直流等离子体喷射沉积金刚石膜的晶粒尺寸、晶粒取向、膜厚、杂质和缺陷对金刚石膜的热导率的影响。结果表明，随着晶粒尺寸的增大，金刚石膜的热导率先慢后快逐渐增大；随着膜的增厚，热导率先大幅度提高，达到一定值后，变化率变小；晶粒（111）取向对金刚石膜的热导率最有利，其次是（110）；非金刚石碳相和缺陷都降低膜的热导率，但晶间空隙对热导率的影响比非金刚石碳相大。     

金刚石膜/氧化铝陶瓷复合材料的介电特性和热学性能研究

研究了金刚石膜/氧化铝陶瓷复合材料作为超高速、大功率集成电路封装基板材料的可行性。采用电容法测量了复合材料的介电性质,结果表明在氧化铝上沉积金刚石膜,能有效降低基片材料的介电系数。碳离子预注入处理使介电损耗降低(从5×10^-3降低到2×10^-3),且频率稳定性更好。金刚石膜的沉积可明显提高基片的热导率,随着薄膜厚度的增加,复合材料的热导率单调递增。当薄膜厚度超过100μm时复合材料的介电系数下降到6.5、热导率上升至3.98W/cm·K,热导率接近氧化铝的20倍。     

SOI built-in heat spreader with temperature and pressure integrated sensors for cooling optimization and in situ monitoring

This contribution presents an original solution for sensor integration into a heat spreader which is directly micromachined into the silicon substrate of the device to be cooled. Having both a high thermal conductivity coefficient and a high level of miniaturization, the vapor chamber heat spreader provides a high robustness due to the absence of any moving pumping parts. Simulation results as well as experimental results obtained with a prototype of the heat spreader with integrated temperature and pressure microsensors are presented. The results concerning device cooling optimization using the integrated sensors are highlighting the interest of this approach for accurate in situ monitoring and cooling optimization of silicon-integrated heat spreaders.     

Optimization of chemical vapor deposition diamond films growth on steel: correlation between mechanical properties, structure, and composition

In the present work we perform optimization of mechanical and crystalline properties of CVD microcrystalline diamond films grown on steel substrates. A chromium-nitride (Cr-N) interlayer had been previously proposed to serve as a buffer for carbon and iron inter-diffusion and as a matching layer for the widely differing expansion coefficients of diamond and steel. However, adhesion and wear as well as crystalline perfection of diamond films are strongly affected by conditions of both Cr-N interlayer preparation and CVD diamond deposition. In this work we assess the effects of two parameters. The first one is the temperature of the Cr-N interlayer preparation: temperatures in the range of 500 degrees C-800 degrees C were used. The second one is diamond film thickness in the 0.5 microm-2 microm range monitored through variation of the deposition time from approximately 30 min to 2 hours. The mechanical properties of so deposited diamond films were investigated. For this purpose, scratch tests were performed at different indentation loads. The friction coefficient and wear loss were assessed. The mechanical and tribological properties were related to structure, composition, and crystalline perfection of diamond films which were extensively analyzed using different microscopic and spectroscopic techniques. It was found that relatively thick diamond film deposited on the Cr-N interlayer prepared at the temperature similar to that of the CVD process has the best mechanical and adhesion strength. This film was stable without visible cracks around the wear track during all scratch tests with different indentation loads. In other cases, cracking and delamination of the films took place at low to moderate indentation loads.     

Chemically vapour deposited diamond coatings on cemented tungsten carbides: Substrate pretreatments, adhesion and cutting performance

Chemical vapour deposition (CVD) of diamond films onto Co-cemented tungsten carbide (WC-Co) tools and wear parts presents several problems due to interfacial graphitization induced by the binder phase and thermal expansion mismatch of diamond and WC-Co. Methods used to improve diamond film adhesion include substrate-modification processes that create a three-dimensional compositionally graded interface. This paper reviews substrate pretreatments and adhesion issues of chemically vapour deposited diamond films on WC-Co. The combined effect of pretreatments and substrate microstructure on the adhesive toughness and wear rate of CVD diamond in dry machining of highly abrasive materials was analyzed. The role of diamond film surface morphology on chip evacuation in dry milling of ceramics was also investigated by comparing feed forces of coated and uncoated mills. The overall tribological performance of diamond coated mills depended on coating microstructure and smoothness. The use of smother films did allow to reduce cutting forces by facilitating chip evacuation.     

CVD金刚石膜的场发射机制

利用热灯丝化学气相沉积方法在光滑的钼上沉积了金刚石膜,用扫描电子显微镜和Raman谱对金刚石膜进行了分析。结果表明金刚石膜是由许多金刚石晶粒组成,晶粒间界主要是石墨相,并且在膜内有许多缺陷。金刚石膜的场发射结果表明高浓度CH4形成的金刚石膜场发射阈位电场较低浓度CH4形成的金刚石为低。这意味着杂质（如石墨）和缺陷（悬挂键）极大地影响了膜的场发射性能。根据以上结果,提出了一种CVD金刚石膜的场发射机制即膜内的缺陷增强膜内的电场,石墨增大电子的隧穿系数以增强CVD金刚石膜的场发射。     

金刚石—铜薄膜复合材料

用ＣＶＤ法合成了金刚石－铜的复合材料。实验证明,合成金刚石－铜复合材料相对厚度的合适范围ｈ／Ｈ＝５－７。复合材料的热传导系数随合成温度Ｔ０的增高而增大。在Ｔ０＝１２４３Ｋ时α≤７００Ｗ·Ｍ＾－１·Ｋ＾－１,近似于高压人工合成的金刚石 。     

生长温度对CVD金刚石薄膜的影响

系统研究了ＣＶＤ金刚石薄膜成膜过程中生长温度对薄膜质量、生长率和力学性能的影响。研究结果表明：在典型沉积条件下，生长温度愈高、薄膜的晶体质量愈好；但薄膜的应力状况和附着性能变坏；在８００℃时，金刚石薄膜的生长速率最大。讨论了ＣＶＤ金刚石薄膜作为机械工具涂层的最佳生长温度。