微波电子回旋共振等离子体增强化学气相沉积法沉积氟化非晶碳薄膜的研究

使用三氟甲烷和苯的混合气体,利用微波电子回旋共振等离子体增强化学气相沉积法制备了F/C比在0.11—0.62之间的α-C∶F薄膜.研究了微波功率对薄膜沉积和结构的影响,发现微波功率的升高提高了薄膜的沉积速率,降低了薄膜的F/C比,也降低了薄膜中CF和CF₃基团的密度,而使CF₂基团的密度保持不变.在高微波功率下可以获得主要由CF₂基团和C=C结构组成的α-C∶F薄膜.薄膜的介电频率关系(1×10³—1×10⁶Hz)和损耗频率关系(1×10²—1×10⁵Hz)均呈指数规律减小,是缺陷中心间简单隧穿引起的跳跃导电所致.α-C∶F薄膜的介电极化主要来源于电子极化 关键词： 氟化非晶碳薄膜 ECR等离子体沉积 键结构 介电性质     

真空退火对氟化非晶碳薄膜结构的影响

在苯(C6H6)和四氟化碳(CF4)混合气体中,用微波电子回旋共振等离子体化学气相沉积技术(ECRCVD)在不同功率下制备了氟化非晶碳膜(aC:F),为了检测膜的热稳定性对其进行了真空退火处理,测量了退火前后膜厚的变化率,并用傅里叶变换红外吸收光谱(FTIR)研究了其结构的变化.结果表明,膜厚变化率与沉积功率有关;400℃退火后低功率下沉积的膜的结构变化显著,高功率下沉积的膜则呈现了较好的热稳定性. 关键词： ECR-CVD aC:F薄膜 真空退火     

电子回旋共振等离子体增强沉积氟化非晶碳薄膜的光学性质

用紫外可见光透射光谱(UV-VIS)并结合键结构的X射线光电子能谱(XPS)和红外谱(FTIR)分析,研究了电子回旋共振等离子体增强化学气相沉积法制备的氟化非晶碳薄膜的光吸收和光学带隙性质.在微波功率为140—700W、源气体CHF₃∶C₆H₆比例为1∶1—10∶1条件下沉积的薄膜,光学带隙在1.76—2.85eV之间.薄膜中氟的引入对吸收边和光学带隙产生较大的影响,吸收边随氟含量的提高而增大,光学带隙则主要取决于CF键的含量,是由于强电负 关键词： 氟化非晶碳薄膜 光吸收与光学带隙 电子回旋共振等离子体     

电子回旋共振微波等离子体化学气相沉积

本文叙述了电子回旋共振微波等离子体化学气相沉积（ＥＣＲＰＣＶＤ）的工作原理、特点及其应用．ＥＣＲＰＣＶ Ｄ由放电室、淀积室、微波系统、磁场线圈、气路与真空系统组成．处于放电室的等离子体在磁场中做回旋运动，使电子的回旋运动频率与微波频率相同；处于回旋共振条件下的电子有效地吸收微波功率而获得高的能量，从而产生高活性和高密度的等离子体．电离度大于１０％，电子密度为１０１３ｃｍ３．ＥＣＲＰＣＶＤ可在低的气体流量、衬底不加热的情况下高速淀积高质量薄膜．以该技术淀积的Ｓｉ，Ｎ４，ＳｉＯ２薄膜可分别与高温ＣＶＤ的Ｓｉ３Ｎ４高温热氧化的ＳｉＯ２相比拟．ＥＣＲＰＣＶＤ淀积ａ－Ｓｉ：Ｈ淀积速率为通常ＣＶＤ的２０倍，而性能与射频ＣＶＤ淀积的ａ－Ｓｉ：Ｈ相当．ＥＣＲＰＣＶＤ 已成功用于淀积多种薄膜。     

氟化非晶碳薄膜的光学带隙分析

研究了CHF3C6H6沉积的氟化非晶碳(αC∶F)薄膜的光学带隙.发现αC∶F薄膜光学带隙的大小取决于薄膜中C—F,CC的相对含量.这是由于CC形成的窄带隙π键和C—F形成的宽带隙σ键含量的相对变化,改变了带边态密度分布的结果.在微波功率为140—700W、沉积气压为01—10Pa、源气体CHF3∶C6H6流量比为1∶1—10∶1条件下沉积的αC∶F薄膜,光学带隙在176—398eV之间 关键词： 氟化非晶碳(αC∶F)薄膜 光学带隙 键结构     

CC双键对氟化非晶碳薄膜I-V特性的影响

研究了电子回旋共振等离子体技术沉积的氟化非晶碳 (a_C :F)薄膜的电学性质 .发现对于不同C_Fx 含量的薄膜 ,CC含量的增大对薄膜的导电行为具有不同的影响 .薄膜的直流I_V特性呈现I =aV bVn规律 ,是低场强区的欧姆导电和高场强区的空间电荷限流 (SCLC)组成的导电过程 .由于非晶材料的空间电荷限流与带尾态密度的分布密切相关 ,而a_C :F薄膜中CC的含量决定带尾态密度的分布 ,因此a_C :F薄膜在高场下的空间电荷限流是由薄膜中 CC 决定的导电过程 .     

电子回旋共振等离子体增强化学气相沉积a-CF_x薄膜的化学键结构

使用CHF3 和C6H6混合气体做气源 ,在一个电子回旋共振等离子体增强化学气相沉积装置中制备了氟化非晶碳 (a CFx)薄膜 .利用发射光谱研究了等离子体中形成的各种碳 氟、碳 氢基团随放电宏观参量的变化规律 ,对薄膜做了傅里叶变换红外光谱和X射线光电子能谱分析 ,证实等离子体中的CF2 ,CF和CH基团是控制薄膜生长、碳 /氟成分比和化学键结构的主要前驱物     

微波电子回旋共振-化学气相沉积SiN_x薄膜的光学性能研究

研究了微波电子回旋共振－化学气相沉积ＳｉＮｘ薄膜的光学性能，这种ＳｉＮｘ薄膜具有透光谱宽、透光率高的特点，总结了透光谱、折射率、光隙能随微波功率、基片温度的变化关系     

用化学气相沉积法制备石墨烯薄膜及其电学性能研究

以甲烷作为反应气体、利用高温化学气相沉积法分别在纯硅片和镀镍镉过渡层硅片上沉积石墨烯薄膜,应用金相显微镜和电学特性测试分析了700,900,950℃温度下生长的石墨烯薄膜的表面形貌、伏安特性及其他电学特性.发现镍铬过渡层具有显著的催化作用,可有效降低石墨烯的生长温度.随着生长温度的升高,样品中电子迁移率随之增大,伏安特性的线性度也越好.对纯硅片上生长的石墨烯,发现高温有利于甲烷有效分解和成核,可有效提高表面电子浓度和电子迁移率,其迁移率可达到2.52×104 cm2/V.     

微波电子回旋共振—化学气相沉只SiNx薄膜的光学性能研究

研究了微波电子回旋共振－化学气相沉积ＳｉＮｘ薄膜的光学性能，这种ＳｉＮｘ薄膜具有透光谱宽，透光率高的特点，总结了透光谱，折射率，光隙能随微波功率，基片温度的变化关系。     

Intertwisted fibrillar diamond-like carbon films prepared by electron cyclotron resonance microwave plasma enhanced chemical vapour deposition

In this paper, the structures, optical and mechanical properties of diamond-like carbon films are studied, which are prepared by a self-fabricated electron cyclotron resonance microwave plasma chemical vapour deposition method at room temperature in the ambient gases of mixed acetylene and nitrogen. The morphology and microstructure of the processed film are characterized by the atomic force microscope image, Raman spectra and middle Fourier transform infrared transmittance spectra, which reveal that there is an intertwisted fibrillar diamond-like structure in the film and the film is mainly composed of sp^3 CH, sp^3 C—C, sp^2 C═C, C═N and C_{60}. The film micro-hardness and bulk modulus are measured by a nano-indenter and the refractive constant and deposition rate are also calculated.     

Structure and hardness of a-C:H films prepared by middle frequency plasma chemical vapor deposition

a-C:H films were prepared by middle frequency plasma chemical vapor deposition (MF-PCVD) on silicon substrates from two hydrocarbon source gases, CH₄ and a mixture of C₂H₂ + H₂, at varying bias voltage amplitudes. Raman spectroscopy shows that the structure of the a-C:H films deposited from these two precursors is different. For the films deposited from CH₄, the G peak position around 1520 cm⁻¹ and the small intensity ratio of D peak to G peak (I(D)/I(G)) indicate that the C-C sp³ fraction in this film is about 20 at.%. These films are diamond-like a-C:H films. For the films deposited from C₂H₂ + H₂, the Raman results indicate that their structure is close to graphite-like amorphous carbon. The hardness and elastic modulus of the films deposited from CH₄ increase with increasing bias voltage, while a decrease of hardness and elastic modulus of the films deposited from a mixture of C₂H₂ + H₂ with increasing bias voltage is observed.     

退火对含氮氟非晶碳膜结构及光学带隙的影响

采用射频等离子体增强化学气相沉积法,在不同条件下制备了含氮氟非晶碳膜,着重考察了退火温度对膜结构和光学带隙的影响. 研究发现：在350℃时,膜仍很稳定,当退火温度达到400℃时,其内各化学键的相对含量发生很大的改变. 膜的光学带隙随着退火温度的升高而增大,红外和拉曼光谱分析显示其原因是：退火使得膜内F的相对浓度降低,sp²相对含量升高,导致σ-σ^*带边态密度降低. 关键词： 含氮氟非晶碳膜 退火 光学带隙     

Formation of CNx thin films by reactive pulsed laser deposition assisted by electron cyclotron resonance microwave discharge

Amorphous carbon nitride thin films were synthesized by pulsed laser deposition combined with electron cyclotron resonance (ECR) microwave discharge in nitrogen gas. The ECR discharge supplies active nitrogen species in the deposition environment and to the growing film surface, enhancing the film growth in complex processes accompanied by chemical reaction. The synthesized films were characterized by Rutherford backscattering spectroscopy (RBS), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. The films were determined to consist purely of carbon and nitrogen with a nitrogen concentration of 42%, and have a thickness of 550 nm over which carbon and nitrogen are well distributed. Structural characterizations based on XPS, FTIR and Raman analysis showed that these films appear to contain several bonding configurations between carbon and nitrogen with a small amount of C≡N bonds compared with other bonding states. Received: 31 August 2000 / Accepted: 12 December 2000 / Published online: 23 May 2001     

Thermal stability of ultrathin amorphous carbon films synthesized by plasma-enhanced chemical vapor deposition and filtered cathodic vacuum arc

Abstract

Ultrathin hydrogenated amorphous carbon (a-C:H) films deposited by plasma-enhanced chemical vapor deposition (PECVD) and hydrogen-free amorphous carbon (a-C) films of similar thickness deposited by filtered cathodic vacuum arc (FCVA) were subjected to rapid thermal annealing (RTA). Cross-sectional transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) were used to study the structural stability of the films. While RTA increased the thickness of the intermixing layer and decreased the sp³ content of the a-C:H films, it did not affect the thickness or the sp³ content of the a-C films. The superior structural stability of the FCVA a-C films compared with PECVD a-C:H films, demonstrated by the TEM and EELS results of this study, illustrates the high potential of these films as protective overcoats in applications where rapid heating is critical to the device functionality and performance, such as heat-assisted magnetic recording.     

Electron field emission characteristics of nano-catkin carbon films deposited by electron cyclotron resonance microwave plasma chemical vapour deposition

This paper reported that the nano-catkin carbon films were prepared on Si substrates by means of electron cyclotron resonance microwave plasma chemical vapour deposition in a hydrogen and methane mixture. The surface morphology and the structure of the fabricated films were characterized by using scanning electron microscopes and Raman spectroscopy, respectively. The stable field emission properties with a low threshold field of 5V/μm corresponding to a current density of about 1μA/cm^2 and a current density of 3.2mA/cm^2 at an electric field of 10V/μm were obtained from the carbon film deposited at CH4 concentration of 8%. The mechanism that the threshold field decreased with the increase of the CH4 concentration and the high emission current appeared at the high CH4 concentration was explained by using the Fowler-Nordheim theory.     

Nitrogen incorporation in amorphous SiCN layers prepared from electron cyclotron resonance plasmas

Electron cyclotron resonance plasma chemical vapor deposition with nitrogen, methane, and argon-diluted silane as precursors has been used to prepare SiCN thin films. Optical emission from CN species in the plasma has been observed. Infrared measurements show that most of the nitrogen is incorporated to the thin solid films in the form of Si-N, C=N and C≡N bonds suggesting a basic structure of incomplete SiN tetrahedra with C=N and C≡N bridging bonds. The deposited films are nearly transparent in the visible range with a weak absorption threshold between 2.2 and 3.5 eV. Received: 3 April 1998 / Accepted: 5 January 1999 / Published online: 31 March 1999     

Effects of flow ratios on surface morphology and structure of hydrogenated amorphous carbon films prepared by microwave plasma chemical vapor deposition

A series of hydrogenated amorphous carbon (a-C:H) films were deposited on silicon substrates by microwave plasma chemical vapor deposition technique with a mixture of hydrogen and acetylene. The effects of flow ratio of hydrogen to acetylene on surface morphology and structure of a-C:H films were investigated using surface-enhanced Raman spectroscopy and scanning probe microscope (SPM) in the tapping AFM mode. Raman data imply a transition from graphite-like phase to diamond-like bonding configurations when the flow ratio increases. AFM measurements show that the increase in hydrogen content, to some extent, can smoothen the surface morphology and decrease the RMS roughness. Excessive hydrogen is found to cause the formation of polymeric hydrocarbon clusters in the films and reduce deposition rate.     

Low-temperature synthesis of AlN films through electron cyclotron resonance plasma-aided reactive pulsed laser deposition

Combination of pulsed laser ablation with electron cyclotron resonance microwave discharge was demonstrated for a novel method for low-temperature thin film growth. Aluminum nitride thin films were synthesized on silicon substrates at temperatures below 80 °C by means of reactive pulsed laser deposition in nitrogen plasma generated from the electron cyclotron resonance discharge. The synthesized films show a very smooth surface and were found to have a stoichiometric AlN composition. X-ray photoelectron spectroscopy analysis evidenced the formation of aluminum nitride compound. Fourier transform infrared spectroscopy revealed the characteristic phonon modes of AlN. The AlN films were observed to be highly transparent in the visible and near-IR regions and have a sharp absorption edge near 190 nm. The band gap of the synthesized AlN films was determined to be 5.7 eV. The mechanisms responsible for the low-temperature film synthesis are also discussed in the paper. The nitrogen plasma facilitates the nitride formation and enhances the film growth. Received: 17 March 2000 / Accepted: 28 March 2000 / Published online: 23 May 2001