小圆平面靶磁控溅射镀膜均匀性研究

本文从圆平面靶磁控溅射的原理出发,针对圆形平面靶面积小于基片面积的特点进行分析,建立膜厚分布的数学模型,并利用计算机进行模拟计算,目的在于探寻平面靶材面积小于基片面积时影响膜厚均匀性的因素。模拟计算的结果表明:基片偏心自转时,靶基距和偏心距对膜厚分布均有影响。偏心距一定时,随着靶基距的增大,薄膜厚度变小,膜厚均匀性有提高的趋势;靶基距一定时,随着偏心距的增大,膜厚均匀性先变好后变差。当基片自转复合公转时,随着转速比的增大,膜厚均匀性逐渐变好,转速比增大到一定程度后,它对膜厚均匀性的影响逐渐变小。圆形平面靶的刻蚀环范围的变化对薄膜的均匀性有一定的影响。这些理论为小圆平面磁控溅射系统的设计和实际应用提供了理论依据。     

电磁阴极磁场分布对磁控溅射系统伏安特性的影响

本文设计了一种新型圆形平面阴极磁控溅射源.该源具有独特的三极线圈结构,改变各线圈励磁电流可调节靶面磁场强度的大小和分布.通过对系统气体放电伏安特性随各线圈励磁电流大小变化规律的分析,以及对距靶面60mm基片台处等离子体束流密度大小和分布的测试,探讨了阴极磁场分布对磁控溅射系统伏安特性的影响.实验结果表明阴极磁场分布模式对气体放电稳定性和等离子体分布影响显著,当阴极磁场呈现收敛型分布时,二次电子被紧密束缚在靶面附近,降低了基片台附近等离子体束流密度,却增大等离子体束流径向分布均匀性.调节非平衡线圈励磁电流,在附加磁场的作用下,阴极磁场呈现发散型分布,二次电子被引向基片台附近,使得基片台附近等离子体束流密度显著增加但径向均匀性变差.     

磁控溅射膜厚均匀性与靶-基距关系的研究

从理论上分析了平面磁控溅射靶沉积薄膜的厚度均匀性.根据磁控溅射阴极靶刻蚀的实际测量数据,建立了靶的刻蚀速率方程,以此为依据,对膜厚均匀性的有关公式进行了讨论.采用计算机计算了基片处于不同靶-基距时,膜厚均匀性的分布.研究结果表明,随着靶基距的增加,膜厚均匀性逐渐变好.在同样的靶基距下,沿靶长度方向的均匀性明显优于宽度方向.最后,通过实验证实了上述结论.     

大面积PECVD平行板电极间电势差分布均匀性数值研究

应用二维准平面电路模型对等离子体增强化学气相沉积(PECVD)大面积平行板电极间电势差分布均匀性进行了数值研究.计算结果表明:在等离子体存在的条件下,电极间电势差分布非均匀性与真空下相比大大增加,电极间的电势驻波效应显著增强,在甚高频条件下会有一阶电势驻波节点出现.另外,波长衰减因子对电势差分布非均匀性影响也表明电极间的电势驻波效应在很大程度上是受等离子体辉光条件控制.本文数值计算结果与近来实验报道的相关结果有很好的吻合.     

电感耦合腔室中等离子体特性分析及线圈优化

半导体镀膜均匀性和刻蚀精度的要求越来越高,对镀膜工艺及刻蚀工艺提出了更高的要求。现有的PECVD设备的镀膜特点是中间厚、边缘薄,镀膜均匀性有待提高。本文在研制PECVD设备过程中,通过COMSOL仿真软件,对影响电感耦合产生等离子体的因素进行仿真,结果表明：电子密度随着极间距、腔室压力、线圈功率的增大而增大。应用仿真软件的等离子体、AC/DC、优化模块进行线圈摆放位置的优化,以自定义的径向电子密度检测线上的梯度值为目标函数,通过约束函数使线圈径向移动,得到等离子体分布均匀的线圈分布图,优化后的电子密度均匀性提高34.7%。本文的研究成果应用于自主研制的PECVD设备之中,效果好,满足了用户要求。     

弱磁场对SnO2薄膜性能的影响

利用等离子体增强化学气相沉积（PECVD）技术制备了SnO2薄膜。实验中通过改变磁镜场的磁镜比和磁场大小,研究了弱磁场对SnO2薄膜方块电阻及电阻分布的影响。实验结果表明,随着磁镜比和磁场强度的增加,SnO2薄膜的方块电阻在降低,且电阻分布变得比较均匀;但是,当磁镜比超过5．5时,SnO2薄膜的电阻分布却变得越来越不均匀。     

弱磁场对SnO2薄膜性能的影响

利用等离子体增强化学气相沉积（PECVD）技术制备了SnO2薄膜。实验中通过改变磁镜场的磁镜比和磁场大小,研究了弱磁场对SnO2薄膜方块电阻及电阻分布的影响。实验结果表明,随着磁比和磁场强度的增加,SnO2薄膜的方块电阻在降低,且电阻分布变得比较均匀;但是,当磁镜比超过5．5时,SnO2薄膜的电阻分布变得越来越不均匀。     

基片的运动方式对磁控溅射矩形靶镀膜均匀性的影响

本文从理论上分析了磁控溅射镀膜中基片的运动方式对沉积薄膜厚度均匀性的影响。在考虑了溅射环内不同位置刻蚀权重的情况下,对静止、直线往复运动(以下简称平动)、平动结合转动、平动结合转动并在折返处停留自旋四种运动方式,根据余弦定律对矩形靶在圆形基片上溅射的膜厚分布进行物理建模和仿真研究,并计算出相应的镀膜均匀度。研究结果表明,相比静止模式,平动时的膜厚均匀性有显著改善,平动结合转动的膜厚均匀性优于平动模式;但在前三种模式下,基片上的膜厚分布均为中心厚,边缘薄。而当采用第四种模式时,膜厚分布不再呈单调下降的趋势,延长停留时间会使膜厚分布发生翻转,变为中间薄、边缘厚,中间存在一个最佳的停留时间使得膜厚均匀性最好。     

电极间距对防原子氧聚硅氧烷薄膜性能的影响

与传统制备防护薄膜的方法相比，等离子体聚合法是一种更高效、干燥和简易的制备方法，可以在各种基底上制备数百纳米厚的致密薄膜涂层。采用等离子增强化学气相沉积(PECVD)法在大面积柔性聚酰亚胺Kapton基底上制备了聚硅氧烷防原子氧薄膜。用SEM、AFM、FTIR和XPS等表征分析了电极间距对聚硅氧烷薄膜性能的影响。结果表明，减小电极间距加速了单体的解离和碳基成分的氧化。随着电极距离的减小，薄膜的沉积速度增大，薄膜从有机无机聚硅氧烷薄膜(SiO_xC_yH_z)向无机薄膜(SiO₂)转化。薄膜中高解离能Si-O键的增多，降低了原子氧的侵蚀率。研究结果为用PECVD方法制备其他有机硅功能薄膜奠定了技术基础。     

永磁电子回旋共振等离子体化学气相沉积系统

研制了一台永磁ECR等离子体化学气相沉积系统.通过同轴开口电介质空腔产生表面波,利用高磁能积Nd-Fe-B磁钢块的合理分布形成高强磁场,通过共振磁场区域内的电子回旋共振效应产生大面积均匀的高密度等离子体.进行了ECR等离子体化学气相沉积氧化硅和氮化硅薄膜工艺的研究.6英寸片内膜厚均匀性优于95%,沉积速率高于100 nm/min,FTIR光谱分析表明薄膜中H含量很低.     

Investigation of the properties of diamond-like carbon thin films deposited by single and dual-mode plasma enhanced chemical vapor deposition

In this study diamond-like carbon (DLC) films were deposited by a dual-mode (radio frequency/microwave) reactor. A mixture of hydrogen and methane was used for deposition of DLC films. The film structure, thickness, roughness, refractive index of the films and plasma elements were investigated as a function of the radio frequency (RF) and microwave (MW) power, gas ratio and substrate substance. It was shown that by increasing the H₂ content, the refractive index grows to 2.63, the growth rate decreases to 10 (nm/min) and the surface roughness drops to 0.824 nm. Taking into consideration the RF power it was found that, as the power increases, the growth rate increases to 11.6 (nm/min), the variations of the refractive index and the roughness were continuously increasing, up to a certain limit of RF power. The Raman G-band peak position was less dependent on RF power for the glass substrate than that of the Si substrate and a converse tendency exists with increasing the hydrogen content. Adding MW plasma to the RF discharge (dual-mode) leads to an increase of the thickness and roughness of the films, which is attributed to the density enhancement of ions and radicals. Also, optical emission spectroscopy is used to study the plasma elements.     

基片与膜厚对硬质薄膜力学性能的影响

采用毫牛力学探针技术的两步压入试验法研究了高速钢和不锈钢基片上不同厚度TiN薄膜的硬度和弹性模量。结果表明 :采用同样工艺制备的TiN薄膜 ,其力学性能随基片类型和膜厚的不同有明显变化。薄膜的硬度和弹性模量随膜厚的增加而提高 ;基体硬度的提高也使薄膜呈现较高的硬度和模量。分析认为薄膜内应力状态的改变是产生这些现象的主要原因。     

Dielectric substrate self-bias and plasma confinement in two-dimensional scanning radio frequency plasma-enhanced chemical vapour deposition

A two-dimensional scanning radio frequency (RF) plasma method was developed for large area deposition in order to avoid difficulties encountered in conventional large RF plasma systems, offering precision control of plasma, improved uniformity of thickness and microstructure, and simplicity of system design. Guarded electrode houses were introduced to form localized plasma thus parasitic plasma or parasitic deposition outside the localized plasma region was eliminated. Different electrode configurations were studied and optimized. Self-bias on dielectric substrate was studied for different electrode configurations as a function of RF power, pressure, and gases. Eliminating parasitic plasma by fully shielding the basing electrode resulted in monitoring signal losses of self-bias. Introducing an isolated plasma house for the biasing electrode enabled the recovery of the self-bias on the biasing electrode without parasitic deposition on substrate outside the localized plasma region. Uniformity optimization within the localized plasma region is no longer a concern in this system. Thickness profile control was achieved by scanning the plasma source over the large substrate. TEM analysis showed that homogenous films were deposited in the scanning deposition system.     

Lithium cobalt oxide thin films deposited at low temperature by ionized magnetron sputtering

Thin films of lithium cobalt oxides have been deposited by ionized magnetron sputter deposition with and without substrate heating. The technique uses a built-in radio frequency coil to generate an inductively coupled plasma (ICP) confined close to the substrate. The ICP plasma results in ion bombardment on the film surface, which serves as an extra energy input during film growth. Therefore, the film properties can be modified at a relatively lower temperature. The plasma irradiation induces variations of crystallography and morphology, as characterized by X-ray diffraction and scanning electron microscopy. The deposited films were tested as cathodes for lithium batteries, and the discharge curves were measured to compare the electrochemical properties of the deposited films. Applying suitable plasma irradiation, well crystallized LiCoO₂ phase was obtained at 350 °C (substrate temperature), which was much lower than the temperature (700 °C-750 °C) for conventional post anneal process. The LiCoO₂ films, fabricated under in-situ plasma irradiation and a relatively lower substrate temperature (350 °C), showed a discharge potential plateau at 4.3 V-3.8 V with a capacity of ∼ 110 mAh/g as discharged to 1.5 V.     

Improvement of adhesion of DLC coating on nitinol substrate by hybrid ion beam deposition technique

Diamond-like carbon (DLC) films were prepared for a protective coating on nitinol substrate by hybrid ion beam deposition technique with an acetelene as a source of hydrocarbon ions. An amorphous silicon (a-Si) interlayer was deposited on the substrates to ensure better adhesion of the DLC films followed by Ar ion beam treatment. The film thickness increased with increase in ion gun anode voltage. The residual stresses in the DLC films decreased with increase in ion gun anode voltage and film thickness, while the stress values were independent of the radio frequency (RF) bias voltage. The adhesion of the DLC film was improved by surface treatment with argon ion beam for longer time and by increasing the thickness of a-Si interlayer.     

High-throughput characterization of film thickness in thin film materials libraries by digital holographic microscopy

A high-throughput characterization technique based on digital holography for mapping film thickness in thin-film materials libraries was developed. Digital holographic microscopy is used for fully automatic measurements of the thickness of patterned films with nanometer resolution. The method has several significant advantages over conventional stylus profilometry: it is contactless and fast, substrate bending is compensated, and the experimental setup is simple. Patterned films prepared by different combinatorial thin-film approaches were characterized to investigate and demonstrate this method. The results show that this technique is valuable for the quick, reliable and high-throughput determination of the film thickness distribution in combinatorial materials research. Importantly, it can also be applied to thin films that have been structured by shadow masking.     

Production of solar absorbing cermet films by dual cathode d.c. magnetron sputtering

A technique using d.c. reactive sputtering from two cathodes for the production of graded-index solar selective cermet films is described. Two variations are presented, one in which the grading is carried out by changing the electrical inputs alone, and the other in which the substrate is translated through a flux of sputtered material that is constant in time. The second variation employs a magnetron source. The coatings produced are iron-silicon oxide and copper-aluminium oxide. The annealing behaviour of the films was studied and the iron-silicon oxide film was found to be stable in vacuum up to 400°C.     

High-throughput characterization of film thickness in thin film materials libraries by digital holographic microscopy

Abstract

A high-throughput characterization technique based on digital holography for mapping film thickness in thin-film materials libraries was developed. Digital holographic microscopy is used for fully automatic measurements of the thickness of patterned films with nanometer resolution. The method has several significant advantages over conventional stylus profilometry: it is contactless and fast, substrate bending is compensated, and the experimental setup is simple. Patterned films prepared by different combinatorial thin-film approaches were characterized to investigate and demonstrate this method. The results show that this technique is valuable for the quick, reliable and high-throughput determination of the film thickness distribution in combinatorial materials research. Importantly, it can also be applied to thin films that have been structured by shadow masking.     

Measurement technique for thermal conductivity of thin polymer films

We present a modified steady-state heat flow technique, which allows measuring the thermal conductivity of films applied on a substrate. The measurement technique with the here presented setup provides an accuracy (overestimation) of 5-10% for film thickness up to 100 μm. For thicker films a correction factor based on finite-element simulations has to be used or the geometry has to be adapted. The technique is validated with thin glass plates of known thermal conductivity. To demonstrate the application of the technique the thermal conductivity of a thin polymer film of fluorinated acrylate is determined as 0.19 ± 0.02 W/mK.     

Carbon incorporation in silicon-carbon films grown at different substrate temperatures

Hydrogenated microcrystalline silicon-carbon thin films have been deposited by plasma enhanced chemical vapour deposition technique at the substrate temperatures of 250 °C and 400 °C varying the radio frequency (RF) power in the 10-100 W range. The effects of substrate temperature and RF power on the structural, compositional, optical, and electrical properties have been investigated. The increase of substrate temperature or RF power leads to a decrease of crystallinity degree and an enhancement of carbon content. Optical absorption in the UV-visible region and electrical conductivity are affected in a different way by the RF power and substrate temperature variations. Silicon grain nucleation of films deposited at the temperature of 250 °C on commercial doped tin oxide substrate has been explored, for different RF power, by means of X-ray diffraction measurements.