ICPECVD类金刚石膜沉积过程的发射光谱诊断研究

利用发射光谱(Optical emission spectroscopy,OES)对感应耦合等离子体增强化学气相沉积(Inductivelycoupled plasma enhance chemical vapor d印osition,ICPECVD)类金刚石(Diamondlike carbon,DLC)膜过程中的各种基团进行分析,并对不同条件下薄膜沉积速率以及薄膜显微硬度进行测试.分析结果发现,感应耦合等离子体源激发甲烷等离子体中存在比较突出的碳氢离子成分,从而促进形成高硬度的DLC膜.而且射频功率、沉积气压等沉积参数的变化对DLC薄膜沉积过程的中性基团、离子基团以及原子氢等成分都有着明显影响,从而最终影响薄膜沉积过程及薄膜性质.     

射频等离子体法在单晶硅衬底上形成的非晶碳膜及其性质

由离子和离子束技术形成的非晶碳膜具有良好的电绝缘性、对红外及可见光透明、硬度大、耐腐蚀等优良性质,可望在半导体器件、激光器件、太阳电池和材料保护等方面得到应用而受到重视。近年来很多作者先后报道了用未经质量分析的低能碳离子束直接沉积、离子束溅射沉积、离子镀、射频辉光放电离化碳氢化合物的等离子体沉积、经质量分析的低能碳离子束沉积等方法在单晶硅、玻璃、不锈钢等不同衬底上形成非晶碳膜的结果。碳膜的物理性质与沉积条件有密切关系,根据物理性质非晶碳膜大致可以分为三类,即导电、不透明的类石墨膜;绝缘、透明、质软的类聚合物膜;透明、绝缘、硬度大的类金刚石膜。     

The properties of N-doped diamond-like carbon films prepared by helicon wave plasma chemical vapor deposition

In this paper, N-doped diamond-like carbon(DLC) films were deposited on silicon substrates by using helicon wave plasma chemical vapor deposition(HWP-CVD) with the Ar/CH_4/N_2 mixed gas. The surface morphology, structural and mechanical properties of the N-doped DLC films were investigated in detail by scanning electron microscopy(SEM), x-ray photoelectron spectroscopy(XPS), Raman spectra, and atomic force microscopy(AFM). It can be observed from SEM images that surface morphology of the films become compact and uniform due to the incorporation of N. The maximum of the deposition rate of the films is 143 nm min~(-1), which is related to the high plasma density. The results of XPS show that the N incorporates in the films and the C-C sp~3 bond content increases firstly up to the maximum(20%) at 10 sccm of N_2 flow rate, and then decreases with further increase in the N_2 flow rate. The maximum Young's modulus of the films is obtained by the doping of N and reaches 80 GPa at 10 sccm of N_2 flow rate, which is measured by AFM in the scanning probe microscope mode. Meanwhile, friction characteristic of the N-doped DLC films reaches a minimum value of 0.010.     

α-C_xN_y:H_(1-x-y)薄膜的制备和光学性能分析

采用外置式电容耦合低压等离子体化学气相沉积法,以高纯CH4/N2/H2作为反应气体,制备非晶α-CxNy:H1-x-y薄膜。研究了薄膜沉积速率和入射功率之间的关系,随着功率增大,薄膜沉积速率先增大后减小;SEM图像表明薄膜无层状、柱状结构;AFM图像表明薄膜粗糙度在0.2～0.3nm之间;傅里叶红外光谱(FTIR)显示了薄膜的成键情况;紫外-可见-近红外光谱表明,随着入射功率的增大,薄膜的光学带隙逐渐减小。     

EACVD沉积金刚石过程中气相化学研究

利用热阴极直流等离子体化学气相沉积技术分别在ＣＨ４－Ｈ２和Ｃ２Ｈ５ＯＨ－Ｈ２两种不同的工作环境中沉积金刚石膜,同时利用发射光谱对等离子体气相环境进行了原位诊断。在ＣＨ４－Ｈ２和Ｃ２Ｈ５ＯＨ－Ｈ２两种体系中,探测到Ｈ原子和ＣＨ、ＣＨ＾＋、Ｃ２等多种碳氢粒子,发现ＣＨ和ＣＨ＾＋有益于金刚石生长,而Ｃ２是非金刚石相的生长基团。与ＣＨ４－Ｈ２体系所不同的是,在Ｃ２Ｈ５ＯＨ－Ｈ２体系中,还产生了ＣＨＯ、ＣＨ     

The effect of nitrogen concentration on the properties of N-DLC prepared by helicon wave plasma chemical vapor deposition

Nitrogen-doped diamond-like carbon (N-DLC) films were synthesized by helicon wave plasma chemical vapor deposition (HWP-CVD). The mechanism of the plasma influence on the N-DLC structure and properties was revealed by the diagnosis of plasma. The effects of nitrogen doping on the mechanical and hydrophobicity properties of DLC films were studied. The change in the ratio of precursor gas flow reduces the concentration of film-forming groups, resulting in a decrease of growth rate with increasing nitrogen flow rate. The morphology and structure of N-DLC films were characterized by scanning probe microscopy, Raman spectroscopy, and X-ray photoemission spectroscopy. The mechanical properties and wettability of N-DLC were analyzed by an ultra-micro hardness tester and JC2000DM system. The results show that the content ratio of N+ and ${{\rm{N}}}_{2}^{+}$ is positively correlated with the mechanical properties and wettability of N-DLC films. The enhancement hardness and elastic modulus of N-DLC are attributed to the increase in sp3 carbon–nitrogen bond content in the film, reaching 26.5 GPa and 160 GPa respectively. Water contact measurement shows that the increase in the nitrogen-bond structure in N-DLC gives the film excellent hydrophobic properties, and the optimal water contact angle reaches 111.2°. It is shown that HWP technology has unique advantages in the modulation of functional nanomaterials.     

Mechanism of high growth rate for diamond-like carbon films synthesized by helicon wave plasma chemical vapor deposition

A high growth rate fabrication of diamond-like carbon(DLC)films at room temperature was achieved by helicon wave plasma chemical vapor deposition(HWP-CVD)using Ar/CH_4gas mixtures.The microstructure and morphology of the films were characterized by Raman spectroscopy and scanning electron microscopy.The diagnosis of plasma excited by a helicon wave was measured by optical emission spectroscopy and a Langmuir probe.The mechanism of high growth rate fabrication for DLC films by HWP-CVD has been discussed.The growth rate of the DLC films reaches a maximum value of 54μm h~(-1)at the CH_4flow rate of 85 sccm,which is attributed to the higher plasma density during the helicon wave plasma discharge.The CH and H_αradicals play an important role in the growth of DLC films.The results show that the H_αradicals are beneficial to the formation and stabilization of C=C bond from sp~2to sp~3.     

Deposition of organosilicone thin film from hexamethyldisiloxane (HMDSO) with 50kHz/33MHz dual-frequency atmospheric-pressure plasma jet

The deposition of organosilicone thin films from hexamethyldisiloxane(HMDSO) by using a dual-frequency (50 kHz/33 MHz) atmospheric-pressure micro-plasma jet with an admixture of a small volume of HMDSO and Ar was investigated.The topography was measured by using scanning electron microscopy.The chemical bond and composition of these films were analyzed by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy.The results indicated that the as-deposited film was constituted by silicon,carbon,and oxygen elements,and FTIR suggested the films are organosilicon with the organic component (-CHx) and hydroxyl functional group(-OH) connected to the Si-O-Si backbone.Thin-film hardness was recorded by an MH-5-VM Digital Micro-Hardness Tester.Radio frequency power had a strong impact on film hardness and the hardness increased with increasing power.     

Investigation of working pressure on the surface roughness controlling technology of glow discharge polymer films based on the diagnosed plasma

The effects of working pressure on the component, surface morphology, surface roughness, and deposition rate of glow discharge polymer(GDP) films by a trans-2-butene/hydrogen gas mixture were investigated based on plasma characteristics diagnosis. The composition and ion energy distributions of a multi-carbon(C_4H_8/H_2) plasma mixture at different working pressures were diagnosed by an energy-resolved mass spectrometer(MS) during the GDP film deposition process. The Fourier transform infrared spectroscopy(FT–IR), field emission scanning electron microscope(SEM) and white-light interferometer(WLI) results were obtained to investigate the structure, morphology and roughness characterization of the deposited films, respectively. It was found that the degree of ionization of the C_4H_8/H_2 plasma reduces with an increase in the working pressure. At a low working pressure, the C–H fragments exhibited small-mass and high ion energy in plasma. In this case, the film had a low CH_3/CH_2 ratio, and displayed a smooth surface without any holes, cracks or asperities. While the working pressure increased to 15 Pa,the largest number of large-mass fragments led to the deposition rate reaching a maximum of 2.11 μm h~(-1), and to hole defects on the film surface. However, continuing to increase the working pressure, the film surface became smooth again, and the interface between clusters became inconspicuous without etching pits.     

Atomic layer deposition of copper thin film and feasibility of deposition on inner walls of waveguides

Copper thin films were deposited by plasma-enhanced atomic layer deposition at low temperature, using copper(I)-N,N′-di-sec-butylacetamidinate as a precursor and hydrogen as a reductive gas. The influence of temperature, plasma power, mode of plasma, and pulse time, on the deposition rate of copper thin film, the purity of the film and the step coverage were studied.The feasibility of copper film deposition on the inner wall of a carbon fibre reinforced plastic waveguide with high aspect ratio was also studied. The morphology and composition of the thin film were studied by atomic force microscopy and x-ray photoelectron spectroscopy,respectively. The square resistance of the thin film was also tested by a four-probe technique. On the basis of on-line diagnosis, a growth mechanism of copper thin film was put forward, and it was considered that surface functional group played an important role in the process of nucleation and in determining the properties of thin films. A high density of plasma and high free-radical content were helpful for the deposition of copper thin films.     

Deposition of SiC_xH_yO_z thin film on epoxy resin by nanosecond pulsed APPJ for improving the surface insulating performance

Non-thermal plasma surface modification for epoxy resin(EP)to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulatedtransmission line.In this paper,a pulsed Ar dual dielectrics atmospheric-pressure plasma jet(APPJ)was used for Si C_xH_yO_zthin film deposition on EP samples.The film deposition was optimized by varying the treatment time while other parameters were kept at constants(treatment distance:10 mm,precursor flow rate:0.6 l min~(-1),maximum instantaneous power:3.08 k W and single pulse energy:0.18 m J).It was found that the maximum value of flashover voltages for negative and positive voltage were improved by 18%and 13%when the deposition time was3 min,respectively.The flashover voltage reduced as treatment time increased.Moreover,all the surface conductivity,surface charge dissipation rate and surface trap level distribution reached an optimal value when thin film deposition time was 3 min.Other measurements,such as atomic force microscopy and scanning electron microscope for EP surface morphology,Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy for EP surface compositions,optical emission spectra for APPJ deposition process were carried out to better understand the deposition processes and mechanisms.The results indicated that the original organic groups(C–H,C–C,C=O,C=C)were gradually replaced by the Si containing inorganic groups(Si–O–Si and Si–OH).The reduction of C=O in ester group and C=C in p-substituted benzene of the EP samples might be responsible for shallowing the trap level and then enhancing the flashover voltage.However,when the plasma treatment time was longer than 3 min,the significant increase of the surface roughness might increase the trap level depth and then deteriorate the flashover performance.     

A Study on Optical Emission of CF4＋CH4 Plasma and Deposition Mechanisms of a-C ： F, H Films

Fluorinated amorphous carbon (a-C : F, H) films were deposited by inductively coupled plasma using CH4 and CF4 gases. Actinometrical optical emission spectroscopy (AOES) was used to determine the relative concentrations of various radicals, CF, CF2 CH, C2, H and F, in the plasma as a function of gas flow ratio R, R=[CH4]/([CH4] [CF4]). The structural evolution of the films were characterized by Fourier transform infrared transmission (FTIR) spectroscopy. The relationship between the film deposition and the precursor radicals in the plasma was discussed. It was shown that CH radical, as well as CF, CF2, C2 radicals are of the precursors, contributing to a-C : F, H film growth.     

Optical properties of titanium oxide films obtained by cathodic arc plasma deposition

Structural and optical properties of nanometric titanium oxide(TixOy) films obtained by cathodic arc plasma deposition were investigated. Phase analysis by x-ray diffraction and Fouriertransform infrared spectroscopy showed the presence of anatase, rutile, Ti_2O_3, Ti_4O_7 and amorphous phases. Scanning electron microscopy images showed well-developed surface morphology with nano-patterns. Spectroscopic ellipsometry revealed film thicknesses of 53 and50 nm, variable refractive indices dependent on the light wavelength and close to zero extinction coefficients for wavelengths higher than 500 nm. On the basis of ultraviolet–visible spectroscopy data and using the Tauc equation, band gap values for direct and indirect electron transitions were determined.     

Hydrophobic coating of surfaces by plasma polymerization in an RF plasma reactor with an outer planar electrode: synthesis,characterization and biocompatibility

This paper presents the plasma polymerization of poly(hexafluorobutyl acrylate)(PHFBA) thin films on different substrates in an RF plasma reactor with an outer planar electrode. This reactor configuration allows?large area uniformity and fast processing times. Deposition rates of up to60 nm min-1were observed. The influence?of plasma power and substrate temperature on the?deposition rate, structure and wettability of the as-deposited films was?investigated. It was observed that better hydrophobicity was obtained at high plasma power and in low temperature conditions. PHFBA thin films deposited on electrospun poly(acrylonitrile) fiber mats under such conditions resulted in superhydrophobic surfaces with?contact angle values greater than 150°.In?vitro cell studies using human epithelial cells demonstrated the non-toxic nature of the?plasma-polymerized PHFBA films.     

The Effect of Plasma Surface Treatment on a Porous Green Ceramic Film with Polymeric Binder Materials

To reduce time and energy during thermal binder removal in the ceramic process, plasma surface treatment was applied before the lamination process.The adhesion strength in the lamination films was enhanced by oxidative plasma treatment of the porous green ceramic film with polymeric binding materials.The oxygen plasma characteristics were investigated through experimental parameters and weight loss analysis.The experimental results revealed the need for parameter analysis,including gas material,process time,flow rate,and discharge power,and supported a mechanism consisting of competing ablation and deposition processes.The weight loss analysis was conducted for cyclic plasma treatment rather than continuous plasma treatment for the purpose of improving the film’s permeability by suppressing deposition of the ablated species.The cyclic plasma treatment improved the permeability compared to the continuous plasma treatment.     

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.     

Influence of low-energy bombardment of an RF magnetron sputtering discharge on texture formation and stress in ZnO films

In an oxygen planar RF magnetron sputtering discharge, the time-averaged flux and energy of positive ions drifting out of the plasma and striking the substrate surface have been determined as a function of RF discharge power over a range of 100 to 1000 W, and as a function of chamber pressure from 0.2 to 6 Pa by measurement of ion-current density and time-averaged plasma sheath potential at the substrate. These data were related to the resulting crystal structure of the deposited ZnO films which had been studied in detail using well-known methods of X-ray diffraction. The impact energy of the positive ions bombarding the growing film varies from some 10 eV to close 50 eV depending on magnetron RF discharge power and oxygen pressure, respectively. The incident ion flux was found to be below 1× 10¹⁵ cm⁻²s⁻¹ up to 1 × 10¹⁶ cm⁻²s⁻¹, a value of the same order of magnitude as that for the condensing rate of sputtered ZnO species. The structural results obtained show that both the ion energy and the ion flux in the range mentioned above cause significant changes in the degree of crystallinity, preferred orientation and texture sharpness of the deposited ZnO films. Furthermore, positive ion bombardment during film growth has been found to alter the ZnO unit cell dimension up to 2% relative to the equilibrium bulk or powder value which is responsible for the formation of strong compressive residual stress of up to several GPa within the ZnO film. Following these results, one of the criterions for preparing highly c-axis oriented ZnO films with columnar grain structure is to decrease both the energy and the flux of the positive ion bombardment without decreasing the deposition rate of ZnO species. At a such slight-bombardment RF magnetron deposition the compressive residual stress of the ZnO film can be reduced towards zero.     

Properties of the acrylic acid polymers obtained by atmospheric pressure plasma polymerization

Plasma polymers of acrylic acid were obtained using an atmospheric pressure discharge system. The plasma polymerization reactor uses a dielectric barrier discharge, with the polyethylene terephthalate dielectric acting as substrate for deposition. The plasma was characterized by specific electrical measurements, monitoring the applied voltage and the discharge current. Based on the spatially resolved optical emission spectroscopy, we analyzed the distribution of the excited species in the discharge gap, specific plasma temperatures (vibrational and gas temperatures) being calculated with the Boltzmann plot method. The properties of the plasma polymer films were investigated by contact angle measurements, infrared and UV-Vis spectroscopy, scanning electron microscopy. The films produced by plasma polymerization at atmospheric pressure showed a hydrophilic character, in correlation with the strong absorbance of OH groups in the FTIR spectrum. Moreover, the surface of the plasma polymers at micrometric scale is smooth and free of defects without particular features.     

Cleaning of nitrogen-containing carbon contamination by atmospheric pressure plasma jet

Atmospheric pressure plasma jet (APPJ) was used to clean nitrogen-containing carbon films (C–N) fabricated by plasma-assisted chemical vapor deposition method employing the plasma surface interaction linear device at Sichuan University (SCU-PSI). The properties of the contaminated films on the surface of pristine and He-plasma pre-irradiated tungsten matrix, such as morphology, crystalline structure, element composition and chemical structure were characterized by scanning electron microscopy, grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy. The experimental results revealed that the removal of C–N film with a thickness of tens of microns can be realized through APPJ cleaning regardless of the morphology of the substrates. Similar removal rates of 16.82 and 13.78 μm min−1 were obtained for C–N films deposited on a smooth pristine W surface and rough fuzz-covered W surface, respectively. This is a remarkable improvement in comparison to the traditional cleaning method. However, slight surface oxidation was found after APPJ cleaning, but the degree of oxidation was acceptable with an oxidation depth increase of only 3.15 nm. Optical emission spectroscopy analysis and mass spectrometry analysis showed that C–N contamination was mainly removed through chemical reaction with reactive oxygen species during APPJ treatment using air as the working gas. These results make APPJ cleaning a potentially effective method for the rapid removal of C–N films from the wall surfaces of fusion devices.     

强脉冲电子束在聚酯薄膜表面产生的化学气相沉积

一、引言 高功率密度脉冲电子束(>10~9W/cm~2)轰击金属,将引起金属剧烈蒸发,产生高温等离子体。等离子体中的金属离子获得一定能量后将与本底气体分子相互作用而形成化合物。本文介绍在低压氮气环境中,利用强脉冲电子束轰击铜靶,产生了氮铜化合物沉积在聚酯薄膜表面的实验结果。并用ESCA分析束处理过的聚酯薄膜表面的化学组成的变化。