Plasma distribution in the slender bore excited by coaxial rf electrode

A metal coaxial radio-frequency (rf) electrode has been utilized to produce plasma and deposit the coating onto the inner wall of the tubes. The inner electrode acts both as a plasma source and as a sputtering target to achieve plasma-based IBAD. The non-uniformity of thickness of deposited films and plasma density in the bore has been investigated for tubes with different lengths and inner diameters. The experimental results demonstrate that plasma density is higher at two ends of the tube and lower in the middle section of the tube. The uniformity of plasma density may increase with the inner diameter of tubes increasing, but will decrease with the length of tubes increasing. Copper films have been deposited using this technique and the variation of film thickness agrees with the distribution of plasma density along the bore axis. It is also observed that the uniformity of plasma density is higher than that of film thickness due to diffusion behavior of plasmas.     

基于NS-DSMC耦合方法与Langmuir探针诊断的射频等离子体氧化过程中等离子体分布

采用Navier-Stokes方程和直接模拟蒙特卡罗方法相结合的方式模拟了反应腔内的气体流动,并结合Langmuir探针检测设备分析了气体流速与等离子体密度的关系。结果表明,流体均匀性对等离子体的均匀性有显著影响。在6.5 Pa的压力下,等离子体密度和流速呈正相关,与在大气压下的实验结果一致,说明提高流体均匀性可以提高等离子体的氧化均匀性。     

一种提高MPCVD法制备金刚石膜均匀性的方法

采用自制的1 kW石英钟罩式微波等离子体化学气相沉积装置,以氢气和甲烷作为气源在镜面抛光的(100)面单晶硅片上沉积了金刚石薄膜。实验共制得两个样品,其中一个样品在制备的过程中加装了难熔的金属钽环,利用等离子体易吸附于金属钽环表面的特性,缩小了硅片中间与边缘等离子体密度差异,另外一个样品没有加装难熔的金属钽环。利用激光拉曼光谱仪和扫描电子显微镜(SEM)对制备的样品进行了表征,发现没有加装金属钽环的样品中间位置沉积的金刚石膜质量明显高于边缘位置沉积的金刚石膜,中间位置、离中间5 mm位置、边缘位置沉积膜层的厚度差别很大;加装了金属钽环的样品中间位置与边缘位置沉积的金刚石膜质量差不多,中间位置、离中间5 mm位置、边缘位置沉积膜层的厚度差别不大,上述结果证明金属钽环的加入是一种提高MPCVD法制备金刚石膜均匀性的方法。     

高功率等离子磁控溅射法制备含钛类金刚石碳膜(英文)

为了改善类金刚石碳膜的性能,采用高功率等离子磁控溅射法将含钛非晶碳薄膜沉积在304不锈钢基材上,气源为C2H2-Ar混合气体,金属钛为阴极靶材。为了改善附着力和降低残余应力,制备了含Ti/TiC/DLC多层结构的镀膜。利用GDS、XRD、SEM、Raman光谱法、纳米压痕仪和盘-销摩擦计研究基材偏压及基材与靶材的距离对薄膜性能的影响。结果表明,薄膜具有优良的粘合强度和韧性。     

Analysis of keyhole geometry in plasma arc welding

The key problem for numerical simulation of plasma arc welding （PAW） process is to develop a suitable and adaptive volumetric heat source mode which reflects the physical characteristics of keyhole PAW. To this end, the keyhole geometry under different PAW process conditions must be predicted. In this paper, a mathematical model for determining the keyhole shape is developed with considering the mass and momentum conservation of the in-keyhole plasma jet as well as the pressure equilibrium at the plasma jet/liquid metal boundary. A suitable heat source model related to the keyhole shape is applied to the calculation of PAW weld dimensions. The predicted results are in good agreement with the experimental ones.     

等离子熔射过程中射流与粒子流的加热效应

采用CCD图像采集系统与图像处理技术提取等离子射流长度;以红外测温仪检测的单位时间内基体温度变化来衡量加热效应,研究不同熔射距离与射流长度条件下射流和粉末粒子流对基体的加热效应特点.结果表明,当熔射距离不大于射流长度时,基体温升主要来至于射流加热效应;随着熔射距离增大,射流对基体的加热效应迅速减弱;当熔射距离大于射流长度时,粒子流加热效应比较明显.提出射流长度可以作为合理选择熔射距离的特征评价指标,并通过不同熔射距离条件下熔射皮膜的截面尺寸以及形貌进行验证.     

Study on the active screen plasma nitriding and its nitriding mechanism

The active screen plasma and DC plasma nitriding of the low alloy steel 722M24 are investigated. Experimental results showed that the metallurgical characteristics and hardening effect on 722M24 steel nitrided by AS plasma nitriding at both floating potential and grounded potential were similar to those nitrided by DC plasma nitriding. Particles sputtered from the active screen and deposited on the specimen surface play the role of the nitrogen carrier in AS plasma nitriding. XRD and high-resolution SEM analysis indicated that the particles with sizes in sub-micron scale were Fe_xN (x > 2). Based on metallurgical analysis and Optical Emission Spectrometer (OES) experimental results, an AS plasma nitriding model has been proposed considering that AS plasma nitriding is a multi-stage process, involving sputtering, physical adsorption, desorption, diffusion and deposition.     

On the film density using high power impulse magnetron sputtering

The influence on thin film density using high power impulse magnetron sputtering (HiPIMS) has been investigated for eight different target materials (Al, Ti, Cr, Cu, Zr, Ag, Ta, and Pt). The density values as well as deposition rates have been compared to results obtained from thin films grown by direct current magnetron sputtering (DCMS) under the same experimental conditions. Overall, it was found that the HiPIMS deposited coatings were approximately 5-15% denser compared to the DCMS deposited coatings. This could be attributed to the increased metal ion bombardment commonly seen in HiPIMS discharges, which also was verified using a global plasma model to assess the degree of ionization of sputtered metal. One key feature is that the momentum transfer between the growing film and the incoming metal ions is very efficient due to the equal mass of film and bombarding species, leading to a less pronounced columnar microstructure. As expected the deposition rates were found to be lower for HiPIMS compared to DCMS. For several materials this decrease is not as pronounced as previously reported in the literature, which is shown in the case of Ta, Pt, and Ag with rate_HiPIMS/rate_DCMS ~ 70-85%, while still achieving denser coatings.     

热丝化学气相沉积金刚石薄膜空间场的数值分析

根据热丝化学气相沉积(HFCVD)金刚石薄膜的几何特点和工艺参数,建立了该系统的二维温度场、速度场和密度场 的耦合模型.利用该模型对沉积大面积金刚石薄膜的空间场进行了模拟计算,研究了沉积参数对空间场的影响.结果表明,衬底处 的温度分布和质量流密度的计算值与实测值相吻合.只有气体进口速度对质量流密度的均匀性影响最大,其它沉积参数对衬底温度 的均匀性、质量流密度的均匀性影响不大.从热丝阵列的最低温度出发,优选出沉积100 mm×100 mm、高质量金刚石薄膜比 较适宜的热丝几何参数.     

Characteristics of Cu implantation into Si by PBII using UBMS cathode

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｍｅｔａｌ ｐｌａｓｍａｂａｓｅｄｉｏｎｉｍｐｌａｎｔａｔｉｏｎ(ＭｅＰＢＩＩ)ｉｓｉｎｔｒｉｎｓｉｃａｌｌｙｄｉｆｆｅｒｅｎｔｔｏｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｇａｓｐｌａｓｍａｂａｓｅｄｉｏｎｉｍｐｌａｎｔａｔｉｏｎ (ＧａＰＢＩＩ)ｄｕｅｔｏｔｈｅｃｏｎｄｅｎｓａｂｌｅｆｅａｔｕｒｅ,ｌａｒｇｅｒｃｏｌｌｉｓｉｏｎｃｒｏｓｓｓｅｃｔｉｏｎａｎｄｍｕｌｔｉｖａｌｅｎｔｉｏｎｃｒｅａｔｉｏｎｏｆｔｈｅｍｅｔａｌｐｌａｓｍａ .Ｔｈｅｒｅａｒｅｓｅｖｅｒａｌｋｉｎｄｓｏｆ…     

Influence of bias on properties of carbon films deposited by MCECR plasma sputtering method

The mirror-confinement-type electron cyclotron resonance(MCECR) plasma source has high plasma density and high electron temperature. It is quite useful in many plasma processing, and has been used for etching and thin-film deposition. The carbon films with 40 nm thickness were deposited by MCECR plasma sputtering method on Si, and the influence of substrate bias on the properties of carbon films was studied. The bonding structure of the film was analyzed by the X-ray photoelectron spectroscopy(XPS), the tribological properties were measured by the pin-on-disk(POD) tribometer, the nanohardness of the films was measured by the nanoindenter, and the deposition speed and the refractive index were measured by the ellipse meter. The better substrate bias was obtained, and the better properties of carbon films were obtained.     

Effects of pressure on metal atom transport and plasma properties during arc ion plating of TiAlN

Arc ion plating is used to deposit titanium and aluminum nitrides as wear and corrosion resistant layers on the surface of steel tools. In this study, the deposition efficiency for the evaporated metal atoms in arc ion plating was obtained by a view factor solution for the collisionless transport and a diffusion solution for the continuum transport. In the diffusion solution, the deposition efficiency decreases rapidly with pressure. A global nitrogen plasma model with a set of simplified plasma chemistry was used to investigate the plasma properties at pressures ranging from several mTorr up to 50 mTorr. The results indicate that the electron temperature, the ratio of electric field to gas density, and the nitrogen atom density all decrease with increasing pressure, while the plasma density increases. Based on the combined considerations of deposition efficiency and effective ion bombardment of the films on the substrate, an operating pressure range from 20 to 30 mTorr is recommended for highly efficient (Ti, Al)N coating during film deposition.     

Simulation analysis of double arc in plasma arc welding

Aimed at plasma arc welding, a mathematic model was established according to the theory of magnetic fluid dynamics. The model was numerically analyzed by ANSYS software. The temperature, current density and plasma velocity distributions of normal arc had been simulated and compared with those of double arc. The results show that the appearance of double arc has made the temperature of the nozzle rise up to 5 000 K. The appearance of side arc could make the current density of the main arc decrease, and also make the maximal temperature of the arc reduce.     

Conformality of thermal and plasma enhanced atomic layer deposition on a non-woven fibrous substrate

Alumina was deposited on a non-woven polyester fiber substrate using both thermal and plasma enhanced atomic layer deposition (ALD). The textile was confined inside a one dimensional test structure. The coverage of the ALD film on the nonwoven as a function of depth in the test structure was determined by energy dispersive X-ray spectroscopy (EDX). A model is introduced which links the precursor transport in the nonwoven (transmission, reflection and deposition) with the nonwoven properties (density, fiber surface area, density of surface sites). The experimental results are compared to simulations of the coverage profile. It is shown that longer precursor exposure times result in deposition deeper inside the nonwoven. However, the majority of precursor molecules entering the nonwoven leave the test structure without contributing to film growth. ALD from TMA and oxygen plasma had a very limited penetration into the nonwoven because of radical recombination. This effect is relevant for plasma treatment of fibrous materials in general.     

光学望远镜镜片旋转镀膜修正挡板的仿真设计

目的 提高新疆天文台南山观测基地ZZS1800-1/G真空镀膜机的膜厚均匀性指标。方法 通过建立旋转行星夹具系统的膜厚分布模型,利用高精度数值计算,基于ZZS1800-1/G真空镀膜机,研究镀膜机结构参数与镜面几何结构对膜厚均匀性的影响,分析蒸发源位置、望远镜镜片参数与修正挡板形状的关系,并进行修正挡板的仿真设计与验证。结果 在旋转行星夹具系统中,蒸发源与原点的距离对半径较大的镜面膜厚均匀性的影响最为明显。该距离600 mm以内,在镜面半径小于100 mm时,膜厚均匀性均低于1.7%;镜面半径为600mm时,膜厚均匀性最佳,为23%。加入修正挡板后,膜厚均匀性理论计算值为0.035%。在镀半径为600mm的镜片时,为保证均匀性小于1%,修正挡板的加工形变量要控制在2.2%以内。结论 加入修正挡板可有效提高ZZS1800-1/G真空镀膜机的膜厚均匀性,本文建立的仿真模型可为ZZS1800-1/G真空镀膜机在实际镀膜工作时修正挡板的设计提供理论参考依据。     

横向交变磁场作用下的等离子体弧特性分析

以外加横向交变磁场作用下的等离子体弧为研究对象,建立了等离子体弧摆动幅度和热流密度分布的数学模型.对横向交变磁约束下的等离子体弧射流特性进行理论研究,并分析工艺参数和励磁强度对横向交变磁约束等离子体弧形态和特性的影响规律.结果表明,横向交变磁场可有效控制等离子体弧形态和位置,等离子体弧在横向交变磁场作用下,分布范围增大、热流密度梯度减小.其摆动幅度随磁场强度的增加而增大,但过高的磁场强度会使等离子体弧变得不稳定;相同励磁强度下,气流量和弧电流越小、喷嘴到工件的距离越大,则摆动幅度越大;而工件表面的等离子体弧热流密度分布随励磁强度的增强趋于平坦化;相同励磁条件下,热流密度峰值随气体流量和弧电流的增大而增大、随喷嘴到工件距离的增大而减小.     

小靶大基片镀膜的膜厚均匀性分析

目的通过改变传统基片与靶材的相对运动方式,来实现小靶材在大面积基片上的均匀镀膜。方法采用基片绕中心轴做匀速旋转运动,靶材沿着基片半径做直线间歇运动,并建立了相应的理论模型,通过数值分析软件MATLAB对膜厚进行分析拟合,研究靶基距、偏心距、靶材运动方式对膜层均匀度的影响。结果在靶基距H=30 mm时,膜厚均匀性主要受到两个重要参数的影响:靶材在各径向运动等距点的停顿时间T和移动步长d。与靶材在各径向运动等距点的停顿时间T=C(C为常数)的情况相比,当靶材的停顿时间T与其在基片上的覆盖面积A成正比增加时,膜厚的均匀性得到极大的改善。同时,膜厚的均匀性很大程度上取决于靶材的移动步长,膜层之间的差异性随着移动步长的减小而减小,结果显示当移动步长d=5mm时的膜厚均匀性最佳。改善基片中心附近的膜厚分布可以通过增加靶基距来实现,结果显示在偏心距e=0 mm、靶基距H≥70 mm时,膜厚相对偏差δ均小于0.1。结论该方法改变了传统靶材固定不动的方式,在薄膜沉积过程中,通过调节靶材的移动步长和停顿时间,能有效减小膜层之间的差异,从而获得均匀度较高的薄膜,对实际生产具有指导意义。     

Effect of process parameters on induction plasma reactive deposition of tungsten carbide from tungsten metal powder

1　ＩＮＴＲＯＤＵＴＩＯＮＴｕｎｇｓｔｅｎｃａｒｂｉｄｅｉｓｗｉｄｅｌｙｕｓｅｄａｓｃｕｔｔｉｎｇｔｏｏｌｉｎｓｅｒｔａｎｄｗｅａｒ ｒｅｓｉｓｔａｎｔｃｏａｔｉｎｇｍａｔｅｒｉａｌｂｅｃａｕｓｅｏｆｉｔｓｈｉｇｈｈａｒｄｎｅｓｓａｎｄｇｏｏｄｔｈｅｒｍａｌｓｈｏｃｋｒｅｓｉｓｔａｎｃｅ .Ｔｒａｄｉｔｉｏｎａｌｌｙ ,ｔｕｎｇｓｔｅｎｃａｒｂｉｄｅｉｓｐｒｏｄｕｃｅｄｔｈｒｏｕｇｈｔｈｅｃａｒｂｕｒｉｚａｔｉｏｎｒｅａｃｔｉｏｎｂｅｔｗｅｅｎｔｕｎｇｓｔｅｎｍｅｔａｌａｎｄｃａｒｂｏｎａｔｈｉｇｈｔ…     

Effects of deposition parameters on microstructure and thermal conductivity of diamond films deposited by DC arc plasma jet chemical vapor deposition

The uniform diamond films with 60 mm in diameter were deposited by improved DC arc plasma jet chemical vapor deposition technique. The structure of the film was characterized by scanning electronic microcopy(SEM) and laser Raman spectrometry. The thermal conductivity was measured by a photo thermal deflection technique. The effects of main deposition parameters on microstructure and thermal conductivity of the films were investigated. The results show that high thermal conductivity, 10.0 W/(K-cm), can be obtained at a CH4 concentration of 1.5% (volume fraction) and the substrate temperatures of 880-920 ℃ due to the high density and high purity of the film. A low pressure difference between nozzle and vacuum chamber is also beneficial to the high thermal conductivity.     

圆柱形谐振式MPCVD装置的模拟及调控

目的 在实验室自制的5 kW圆柱形单模微波等离子体化学气相沉积(MPCVD)装置上,系统研究各放电参数对等离子体的影响.方法 采用模拟计算与实验调控相结合的方式,分析微波等离子体、基团的运动和分布与放电参数之间的关系.利用发射光谱诊断等离子体环境,同时,利用SEM和Raman对所沉积的金刚石膜的形貌和质量进行表征,以验证MPCVD装置的调控原则.结果 气压和温度满足Tg=8/3 P关系时,吸收功率密度可达最大.单独提高微波功率和工作气压,能很大程度地增强等离子体的电子密度及改善等离子体球的均匀性,而两者相互之间匹配升高能极大地增加等离子体的电子密度,同时激发更多Hα、Hβ、CH及C2这类适合高质量金刚石膜沉积的活性基团.得到了MPCVD装置长时间稳定运行的等离子体稳定边界,并成功制备出高质量的金刚石膜.结论 功率气压及温度相匹配可以提高吸收功率密度、等离子体密度及均匀性.在圆柱形装置稳定运行的边界条件下,能沉积得到较高质量的金刚石膜.