High-Pressure Plasma Deposition of a-C:H Films by Dielectric-Barrier Discharge

The fabrication of a-C:H films from methane has been performed using dielectric-barrier discharges at atmospheric pressure. The effect of combined-feed gas, such as carbon dioxide, carbon monoxide or acetylene on the formation of a-C:H films has been investigated. It has been demonstrated that the addition of carbon monoxide or acetylene into methane leads to a remarkable improvement in the fabrication of a-C:H films. The characterization of carbon film obtained has been conducted using FT-IR, Raman and SEM.

Optical Characterization of Amorphous Hydrogenated Carbon(a-C:H)Thin Films Prepared by Single RF Plasma Method

Methane （CH4） plasma was used to produce amorphous hydrogenated carbon （a- C：H） films by a single capacitively coupled radio frequency （RF） powered plasma system. The system consists of two parallel electrodes： the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy （OES）. The structural and optical properties were analyzed via Fourier transform infrared （FTIR） spectroscopy, X-ray diffraction （XRD） and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.

a-C∶F∶H films prepared by PECVD

Fluorinated amorphous hydrogenated a-C∶F∶H carbon thin films were deposited using radio frequency plasma enhanced chemical vapor deposition（RF-PECVD） reactor with CF4 and CH4 as source gases and were annealed in a N2 atmosphere. The properties of these films were evaluated by FTIR spectrometry, UV-VIS spectrophotometry and single-wavelength spectroscopic ellipsometry. A correspondence relativity connection between the deposition rate and technology was found. The chemical bonding structures and the content of CHx and CFx in the films are transformed and the optical band gap decreases monotonically with increasing temperature after annealing. The dielectric constant is increased with decreasing content of F in the films and the optical band gap is decreased with decreasing the content of H in the film.

Effect of Chromium on Structure and Tribological Properties of Hydrogenated Cr/a-C:H Films Prepared via a Reactive Magnetron Sputtering System

Hydrogenated Cr-incorporated carbon films （Cr/a-C：H） are deposited successfully by using a dc reactive mag- netron sputtering system. The structure and mechanical properties of the as-deposited Cr/a-C：H films are characterized systematically by field-emission scanning electron microscope, x-ray diffraction, Raman spectra, nanoindentation and scratch. It is shown that optimal Cr metal forms nanocrystalline carbide to improve the hardness, toughness and adhesion strength in the amorphous carbon matrix, which possesses relatively higher nano-hardness of 15. 7 CPa, elastic modulus of 126.8 GPa and best adhesion strength with critical load （Lc） of 36 N for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm. The friction and wear behaviors of as-deposited Cr/a-C：H films are evaluated under both the ambient air and deionized water conditions. The results reveal that it can achieve superior low friction and anti-wear performance for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm under the ambient air condition, and the friction coetllcient and wear rate tested in deionized water condition are relatively lower compared with those tested under the ambient air condition for each film. Superior combination of mechanical and tribological properties for the Cr/a-C：H film should be a good candidate for engineering applications.

Parylene F在V频段MMIC防护上的应用

为了验证Parylene F材料在V频段MMIC防护上的应用,设计了薄膜滤波器、铝基和铜基的可调放大器模块。采用真空气相沉积工艺在滤波器、放大器模块上制作Parylene F膜层。测试结果表明:5μm的膜层使滤波器中心频率向左偏移300~350 MHz,其插损、矩形系数几乎没有变化;5μm膜层使可调放大器模块增益峰值下降约0.1%~0.2%,正常态、衰减态下的增益均出现了漂移现象,但处理前后的增益曲线趋势基本一致;模块的噪声系数峰值增加了1.12~1.78 dB,正常态与衰减态下的噪声系数曲线均出现了漂移,但处理前后的噪声系数曲线趋势基本一致,且铜基腔体的噪声系数恶化较铝基腔体弱。分析结果表明,通过滤波器、可调放大器的补偿设计,可以实现Parylene F在V频段MMIC防护上的应用。

Nanocomposite TiC/a-C：H film prepared on titanium aluminium alloy substrates by PSII assistant MW-ECRCVD

Thin films of titanium carbide and amorphous hydrogenated carbon have been synthesized on titanium aluminium alloy substrates by PSII assisted MW-ECRCVD with a mirror field. The microstructure, chemical composition and mechanical property were investigated. Using XPS and TEM, the films were identified to be a-C：H film containing TiC nanometre grains （namely, the so-called nanocomposite structure）. The size of TiC grains of nanocomposite TiC/DLC film is about 5 nm. The nanocomposite structure has obvious improvement in the mechanical properties of DLC film. The hardness of a-C：H film with Ti is enhanced to 34 G Pa~ while that of a-C：H film without Ti is about 12 G Pa, and the coherent strength is also obviously enhanced at the critical load of about 35N.

Preparation and Characterization of CeO_2-TiO_2/SnO_2:Sb Films Deposited on Glass Substrates by R.F.Sputtering

CeO2-TiO2 films and CeO2-TiO/SnO2：Sb （6 mol%） double films were deposited on glass substrates by radio-frequency magnetron sputtering （R.F. Sputtering）, using SnO2：Sb（6 mol%） target, and CeO2- TiO2 targets with different molar ratio of CeO2 to TiO2 （CeO2：TiO2-0：1.0; 0.1：0.9; 0.2：0.8; 0.3：0.7; 0.4：0.6; 0.5：0.5; 0.6：0.4; 0.7：0.3; 0.8：0.2; 0.9：0.1; 1.0：0）. The films are characterized by UV-visible transmission and infrared reflection spectra, scanning electron microscopy （SEM）, Raman spectroscopy, X-ray photoelectron spectroscopy （XPS） and X-ray diffraction （XRD）, respectively. The obtained results show that the amorphous phases composed of CeO2-TiO2 play an important role in absorbing UV, there are Ce^3-, Ce^4- and Ti^4- on the surface of the films; the glass substrates coated with CeO2-TiO2 （Ce/Ti=0.5：0.5; 0.6：0.4）/SnO2：Sb（6 mol%） double films show high absorbing UV（〉99）, high visible light transmission （75%） and good infrared reflection （〉70%）. The sheet resistance of the films is 30-50 Ω/□. The glass substrates coated with the double functional films can be used as window glass of buildings, automobile and so on.

Structure and tribological properties of Si/a-C:H(Ag)multilayer film in stimulated body fluid

Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated body fluid are investigated.The results show the concentration of Ag first decreases and then increases with the modulation period decreasing from 984 nm to 250 nm.Whereas the C content has an opposite variation trend.Notably,the concentration of Ag plays a more important role than the modulation period in the properties of the multilayer film.The a-C:H sublayer of the film with an appropriate Ag concentration(8.97 at.%)(modulation period of 512 nm)maintains the highest sp3/sp2 ratio,surface roughness and hardness,and excellent tribological property in the stimulated body fluid.An appropriate number of Ag atoms and size of Ag atom allow the Ag atoms to easily enter into the contact interface for load bearing and lubricating.This work proves that the Ag nanoparticles in the a-C:H sublayer plays a more important role in the tribological properties of the composite-multilayer film in stimulated body fluid condition.

Effect of C:F Deposition on Etching of SiCOH Low-κ Films in CHF_3 60 MHz/2 MHz Dual-Frequency Capacitively Coupled Plasma

Effect of C：F deposition on SiCOH etching in a CHF3 dual-frequency capacitively couple plasma, driven by a high-frequency source of 60 MHz （HF） and a low-frequency source of 2 MHz （LF） simultaneously, is investigated. With the increase in LF power, the change of C：F layer from dense C：F layer to porous C：F layer and further to C：F filling gaps was observed, which led to the transition from films deposition to films etching. The change of C：F layer is related to the bombardment by energetic ions and CF2 concentration in the plasma. As the LF power increased to 35 - 40 W, the energetic ions and the low CF2 concentration led to a suppression of C：F deposition. Therefore, the SiCOH films can be etched at higher LF power.

Infrared and Optical Properties of Amorphous Fluorinated Hydrocarbon Films Deposited with the Method of ECR Plasma

Using CH4 and CF4 precursor gases, amorphous fluorinated hydrocarbon (a-C:F:H) films were prepared with the method of microwave electronic cyclotron resonant (ECR) plasma chemical vapor deposition. Deposition rate of the film firstly increases and then decreases with variable flow ratios R {[CF4]/([CF4] + [CH4]} due to the competition between deposition and etching process. Results from Fourier-transform infrared transmission spectroscopy of these films show that C-F bond configuration in a-C:F:H films evolves with the variable gas flow ratios R. The locations of the C-F peaks in IR spectra shift to higher frequency with the increase of R, and finally the structure in films with R >75% takes on a PTFE-like structure, which mainly consists of -CF2- chain. The change of optical band gap Eg deduced by a Tauc plot with R is also discussed.

Electrical Properties of Plasma Deposited Low-Dielectric-Constant Fluorinated Amorphous Carbon Films

Fluorinated amorphous carbon （a-C：F） films were deposited at room temperature using C4Fs and CH4 as precursor gases by electron cyclotron resonance chemical vapour deposition （ECR-CVD）. Chemical structures were analysed using X-ray photoelectron spectroscopy （XPS）. The current conduction shows ohmic behaviour and the leakage current increases with the content of C sp2 in the deposited a-C：F films at a low electric field. The behaviour of the leakage current is well e^plained by the Poole-Frankel mechanism at a high electric field. The interface traps, rather than chemical structures, of a-C：F films determine the PF emission current.

Preparation and characterization of GaN films grown on Ga-diffused Si (111) substrates

Hexagonal GaN films were prepared by nitriding Ga_2O_3 films with flowingammonia. Ga_2O_3 films were deposited on Ga-diffused Si (111) substrates by radio frequency (r.f.)magnetron sputtering. This paper have investigated the change of structural properties of GaN filmsnitrided in NH_3 atmosphere at the temperatures of 850, 900, and 950 deg C for 15 min and nitridedat the temperature of 900 deg C for 10, 15, and 20 min, respectively. X-ray diffraction (XRD),scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectronspectroscopy (XPS) were used to analyze the structure, surface morphology and composition ofsynthesized samples. The results reveal that the as-grown films are polycrystalline GaN withhexagonal wurtzite structure and GaN films with the highest crystal quality can be obtained whennitrided at 900 deg C for 15 min.

Texture ZnO Thin-Films and their Application as Front Electrode in Solar Cells

In this paper, three kinds of textured ZnO thin-films (the first kind has the textured structure with both columnar and polygon, the second posses pyramid-like textured structure only, and the third has the textured structure with both crater-like and pyramid-like), were prepared by three kinds of methods, and the application of these ZnO thin-films as a front electrode in solar cell was studied, respectively. In the first method with negative bias voltage and appropriate sputtering parameters, the textured structure with columnar and polygon on the surface of ZnO thin-film are both existence for the sample prepared by direct magnetron sputtering. Using as a front electrode in solar cell, the photoelectric conversion efficiency Eff of 7.00% was obtained. The second method is that by sputtering on the ZnO:Al self-supporting substrate, and the distribution of pyramid-like was gained. Moreover, the higher (8.25%) photoelectric conversion efficiency of solar cell was got. The last method is that by acid-etching the as-deposited ZnO thin-film which possesses mainly both columnar and polygon structure, and the textured ZnO thin-film with both crater-like and pyramid-like structure was obtained, and the photoelectric conversion efficiency of solar cell is 7.10% when using it as front electrode. These results show that the textured ZnO thin-film prepared on self-supporting substrate is more suitable for using as a front electrode in amorphous silicon cells.

氮掺杂对a-C:F薄膜表面形貌和键结构的影响

用射频等离子体增强化学气相沉积设备制备了氮掺杂a-C:F(氟化非晶碳)薄膜,研究了不同氮源流量比对薄膜表面形貌和键结构的影响。AFM观察结果发现:随氮流量的增加,薄膜表面粗糙度降低,颗粒粒径变小,薄膜更加均匀致密。Raman光谱分析表明:氮源流量的增加会引起薄膜内sp2键态含量增加,即芳香环式结构比例上升,当r(N2/(CF4+CH4+N2))为68%时,ID/IG由未掺N2时的1.591增至4.847,薄膜的热稳定性增强。

ECR-CVD沉积a-C∶F薄膜

采用电子回旋共振等离子体化学气相沉积 (ECR CVD)技术 ,用苯和三氟甲烷混合气体 ,制备了氟化非晶碳膜 (a C∶F)。用红外吸收光谱 (FTIR)和X射线光电子能谱 (XPS)分析了a C∶F薄膜的结构。FTIR结果表明 ,氟主要以C—F、CF2 的形式成键形成a C∶F薄膜 ;XPS结果进一步证明a C∶F膜中存在C—F、CF2 键 。

射频功率对a-C:F薄膜沉积速率和结构的影响

用射频等离子体增强型化学气相沉积法制备了a-C:F薄膜,并研究了射频功率对a-C:F薄膜沉积速率和结构的影响.用椭偏仪测量了薄膜的厚度,并用红外谱(FITR)结合Raman谱研究了其结构的变化.结果表明:薄膜沉积速率在10～14 nm/min之间,主要含有CFx和C=C键.随射频功率的升高,沉积速率先增大后减小,CF3的含量迅速减小,CF和CF2的含量略有增加,薄膜中r(F/C)呈下降的趋势.在较高功率下沉积的薄膜中出现了由sp2和sp3混合微晶结构.

a-C:F薄膜的工艺及热稳定性研究

以CF4和CH4为源气体,用PECVD法制备了不同沉积条件下的a C:F薄膜,测量了薄膜的厚度,研究了薄膜沉积速率和沉积工艺的关系,用傅立叶变换红外谱(FTIR)分析了薄膜的化学键结构,用扫描电镜和原子力显微镜分析了薄膜表面形貌,对薄膜在真空中进行了退火,研究了薄膜的热稳定性。实验表明,沉积速率在5～8nm/min之间,薄膜表面平整、致密,在300℃内有较好的热稳定性。

a-C:F薄膜结构与电学性能研究

采用电子回旋共振等离子体化学气相沉积(ECR-CVD)方法,以C4F8和CH4为源气体,在不同气体流量比R(R=[CH4]/([CH4]+[C4F8]))条件下沉积氟化非晶碳(a-C:F)薄膜。用原子力显微镜(AFM)分析了薄膜的表面形貌。用柯西(Cauchy)模型和Levenberg-Marquardt非线性迭代算法分析了薄膜的椭圆光谱。用X光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)技术分析了薄膜的化学成分。随着气体流量比R的增大a-C:F薄膜C-C键结构增多,薄膜C/F比增大。a-C:F薄膜的介电常数取决于电子极化并随R的增大而上升。a-C:F薄膜导电行为在低场强区域呈现欧姆特性,在高场强区域符合Poole-Frankel机制。随着C-C含量的增大,π价带态和π*导带态之间的带隙减小,电荷陷阱深度减小,陷阱中的电子在场增强热激发作用下更容易进入导带,导致薄膜漏电流增加。

低介电常数a-C:F薄膜结构和热稳定性研究

采用电子回旋共振等离子体化学气相沉积的方法以C4F8和CH4为源气体制备了非晶氟化碳(a-C:F)薄膜.采用傅里叶变换红外光谱(FTIR)和X光电子能谱(XPS)技术分析了a-C:F薄膜化学组分.FTIR分析表明a-C:F薄膜中存在CF=C(1680 cm-1)和位于a-C:F薄膜交联结构末端的CF2=CF (1780 cm-1)结构.C1s峰高斯解叠后结合态与结合能对应关系为:CF3(295 eV),CF2(293 eV),CF(291 eV),C-O(289 eV),C-CFx(x=1～3)(287 eV),以及位于a-C:F薄膜交联结构末端的C-C结合态(285 eV).位于a-C:F薄膜交联结构末端的CF3和C-C结构热稳定性较差,退火后容易生成气态挥发物并导致a-C:F薄膜厚度减小.当C-CFx交联结构增多,且位于a-C:F薄膜交联结构末端的CF3和C-C结构减少时,a-C:F薄膜热稳定性提高.

氟化非晶碳(a-C:F)薄膜的研究

氟化非晶碳(a-C:F)薄膜是一种电、光学新材料。介绍了它的制备方法,对其制备工艺作了较全面的探讨;分析了该膜制备方法和工艺参数对薄膜组分及化学键结构的影响;研究了该膜的电学、光学、热学、力学等物理性质及其在相关方面的应用,并对该膜的物理性质与制备工艺参数的关联作了详细的论述;指出介电常数和热稳定性的矛盾是阻碍该膜实用化的主要原因。