Aluminum Silicate Films Obtained by Low-Pressure Metal-Organic Chemical Vapor Deposition

Amorphous alumina-silica films with film thickness of 0.41–2.69 μm were prepared on glass and silicon substrates by metal-organic chemical vapor deposition using a mixture of aluminum tri-sec-butoxide (ATSB), hexamethyldisilazane (HMDSN), and argon. By controlling the inputs of ATSB and HMDSN, alumina-silica thin films could contain varied compositions and adjustable properties. Basically, the codeposition of alumina and silica to form alumina-silica using ATSB and HMDSN had a faster growth rate than their individual components. The internal stress could be adjusted by deposition temperature and reactant inputs. Adhesion could be improved by having a silicon-rich thin film, whereas an aluminum-rich film could have slightly higher hardness. Optical properties, e.g., refractive index and optical transmittance, were also measured.     

Preparation of Magnesium Nitride Powder by Low-Pressure Chemical Vapor Deposition

Submcrometer-scale magnesium nitride (Mg₃N₂) powder was prepared by low-pressure chemical vapor deposition, i.e., the reaction of Mg vapor with mixed NH₃–N₂ gases at 800°C under a pressure of ∼1 kPa. The mixing ratios of NH₃–N₂ gases were 0% NH₃–100% N₂ (pure N₂), 20% NH₃–80% N₂, 40% NH₃–60% N₂, 60% NH₃–40% N₂, 80% NH₃–20% N₂, and 100% NH₃–0% N₂ (pure NH₃). The reactions between Mg vapor and NH₃–N₂ gases produced platy Mg₃N₂ particles <0.2 μm and acicular particles with long-axis length of ∼0.2 μm, whereas the reaction of Mg vapor with pure NH₃ gas produced spherical Mg₃N₂ particles with diameters of ∼0.1 μm.     

Characterization of Lead Oxide Thin Films Produced by Chemical Vapor Deposition

As a step toward creating a chemical vapor deposition (CVD) process for PbTiO₃ thin films, lead oxide films were deposited and then examined. The reaction was oxidation controlled, with an apparent activation energy of 97 kJ/mol in this low-temperature, low-pressure metalorganic CVD (MOCVD) process. Across the deposition parameters examined, several distinct types of morphology were observed. Growth occurred as a combination of layer-on-layer and island formation. The structural and chemical properties of the lead oxide were examined by Auger electron spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and electron diffraction. Various forms of lead oxide were produced (litharge, massicot, and scrutinyite, singly or in combination with each other). The deposition parameters used in this work showed a tendency to maintain the same crystalline form from the initial nucleation stages through post-deposition annealing. Lead oxide formed readily on SiO₂ surfaces (contrary to studies by other researchers) and, indeed, reacted with the underlying SiO₂ layer.     

Electron Cyclotron Resonance Plasma-Enhanced Metalorganic Chemical Vapor Deposition of Tantalum Oxide Thin Films on Silicon near Room Temperature

Films of tantalum oxide, ranging in thickness from 25 to 2000 nm, were successfully deposited on silicon by the electron cyclotron resonance plasma-enhanced metalorganic chemical vapor deposition (ECR-MOCVD) process at deposition rates of up to 33 nm/min. The films were produced by decomposition of tantalum pentaethoxide into tantalum oxide in an oxygen ECR microwave plasma. The films were amorphous (but fully dense) since the temperature of the substrate, which was unheated, was estimated to be 76–120°C. The growth of the tantalum oxide films was accompanied by the formation of an interlayer of silicon dioxide at the silicon interface. The tantalum oxide films were oxygen rich (relative to Ta₂O₅). The effective relative dielectric constant of these dual-layer dielectrics ranged from ɛ_ef= 8.5 to 24; this range was explained in terms of a bilayer consisting of a 13-nm-thick silicon dioxide layer of ɛ_sx= 4, and a tantalum oxide overgrowth of varying thickness having ɛ_tx∼ 25. A maximum breakdown strength of the films was 6.9 MV/cm and the leakage current at a field of 1 MV/cm was 3.0 × 10^-8. The breakdown properties were related to the presence of stray particles on the substrate; these properties are expected to improve considerably if the processing is carried out in a clean-room environment. The silicon dioxide layer is believed to have grown by the diffusion of oxygen through the tantalum oxide overlayer despite the low substrate temperature.     

Chemical Vapor Deposition of Polymer Thin Films Using Cationic Initiation

Chemical vapor deposition (CVD) is an attractive technique for the fabrication of high‐quality polymer thin films. The scheme used to initiate polymer chain growth is fundamental to controlling polymer thin film chemistry. A new initiation scheme for polymer CVD utilizing cationic initiation with a strong Lewis acid, TiCl₄, in combination with a hydrogen donor, H₂O, is presented. This coinitiation scheme results in polystyrene deposition rates of 139 nm min^?1, relative to just 34 nm min^?1 when TiCl₄ is used alone. Characterization by Fourier transform infrared spectroscopy shows that the polymer structures of polystyrene films prepared by conventional solution‐based techniques and cationic CVD are similar. Synthesis of cross‐linked polymer thin films is also demonstrated by depositing poly(divinylbenzene) and showing its insolubility in a range of solvents. The practical utility of these poly(divinylbenzene) films as corrosion resistant coatings is demonstrated. In 1 n HCl, 200 nm thick films on stainless steel increase the polarization resistance by a factor of 44 relative to bare, untreated stainless steel.     

等离子体化学气相沉积法制备致密性超浸润纳米硅氟薄膜

以含氟丙烯酸酯功能单体和硅烷为原料、无水乙醇为溶剂、氩气为工艺气体,经等离子体化学气相沉积在表面绝缘阻抗(SIR)测试板和无尘布上制得硅氟薄膜.探讨了硅烷种类和用量、含氟单体用量对镀硅氟薄膜试件性能的影响.结果表明,采用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH 570)、γ-氨丙基三乙氧基硅烷(KH 550)和乙烯基三...     

Pulsed-Laser Deposition of Barium Titanate Thin Films

Barium titanate (BaTiO₃) thin films have been deposited on single-crystal magnesia (MgO) substrates by pulsed-laser ablation. Temperature dependence of capacitance measurements show a peak of 110°C, indicative that a ferroelectric phase transition has occurred at this temperature. This value is lower than that determined for single-crystal BaTiO₃, but consistent with that found for BaTiO₃ thin films produced by other methods. It has been demonstrated that the microstructure of the films can be varied by changes in the deposition parameters. Optimizing these variations permits the formation of thin films with controlled microstructures and properties.     

Rapid Formation of Zinc Oxide Films by an Atmospheric-Pressure Chemical Vapor Deposition Method

Zinc oxide films were prepared by an atmospheric-pressure chemical vapor deposition method using (acetylacetonato)-zinc as a source material. Transparent and uniform ZnO films of considerable area (20 × 70 mm, ∼0.3 μm thick) could be obtained easily on a crown glass (CGW #200) with a high deposition rate. The deposition rate first remained constant with increasing substrate temperature ( T _s), then increased abruptly from 120 nm/min at T _s= 550°C to 220 nm/min at T _s= 600°C, and finally stopped increasing above T _s= 600°C. The maximum preferred orientation and best crystallinity of the films were obtained at T _s= 550°C.     

常压化学气相沉积法氮氧化硅薄膜性能的研究

我们用常压化学气相沉积法(APCVD),以SiH4和NH3为先驱体,在较低的温度(＜700℃)下制备氮氧化硅(Si-O-N)薄膜,并对其性能进行了研究.研究结果表明氮氧化硅薄膜能使改性后平板玻璃硬度提高40%,并具有良好的抗高温氧化性,这种薄膜在材料表面改性领域有着广阔的应用前景.     

Metalorganic Chemical Vapor Deposition of Ferroelectric Pb(Zr,Ti)O3 Thin Films

Ferroelectric Pb(Zr_xT_1–x)O₃, films were successfully and reproducibly deposited by both hot–wall metalorganic chemical vapor deposition (MOCVD) and cold-wall MOCVD. One of the important problems associated with the MOCVD techniques is the selection of ideal precursors. After an intensive investigation for the most suitable precursors for MOCVD PZT films, the safe and stable precursors, namely lead tetramethylheptadione [Pb(thd)₂], zirconium tetramethylheptadione [Zr(thd)₄], and titanium ethoxide [Ti(OEt)₄], were chosen. The films were deposited at temperatures as low as 550°C and were single-phase perovskite in the as-deposited state. Also, the films were smooth, specular, crack-free, and uniform, and adhered well to the substrates. The stoichiometry of the films can be easily controlled by varying the individual precursor temperature and/or the flow rate of the carrier gas. Auger electron spectroscopic (AES) depth profile showed good compositional uniformity through the thickness of the films. The AES spectra also showed no carbon contamination in the bulk of the films. As-deposited films were dense and showed uniform and fine grains (≅0.1 μm).The optical properties of the films on the sapphire disks showed high refractive index ( n = 2.413) and low extinction coeflicient ( k = 0.0008) at a wavelength of 632.8 nm. The PZT (82/18) film annealed at 600°C showed a spontaneous polarization of 23.3 μC/cm² and a coercive field of 64.5 kV/cm.     

Growth of Yttria-Stabilized Zirconia Thin Films on Textured Silver Substrates by Chemical Vapor Deposition

The effect of deposition conditions on the growth of yttria-stabilized zirconia (YSZ) films on textured silver substrates using the chemical vapor deposition (CVD) process was investigated. The crystalline structure of the YSZ film depended strongly on the deposition conditions, such as substrate temperature and deposition time. YSZ films prepared at 750°C using β-diketone chelate sources, which had an orientation of c -axis normal to the textured silver substrate surface. The YSZ surface was dense but not rough, and the YSZ film grew granular-like. The cross-sectional image of YSZ film showed the columnar growth feature; the growth rate was ∼20 nm/min.     

Low Temperature Chemical Vapor Deposition of Aluminosilicate Thin Films on Carbon Fibers

We report the deposition of aluminum oxide and aluminosilicate thin films onto carbon fiber substrates, at temperatures of 200° and 250°C, respectively. For aluminosilicate films, the Al/Si ratio of the resultant film varied concomitantly with the composition of the liquid precursor mixture. The growth rate for the oxide films was 15–17 Å/min, comparable with other methods carried out at higher temperatures. Cross-section SEM images indicate that the deposited films are conformal, following the complex topography of the carbon fiber substrate. Preliminary gas-phase IR analysis suggests that the coatings decompose the nerve agent simulant dimethyl methylphosphonate at temperatures as low as 35°C, suggesting the utility of the reported methodology for the design/fabrication of actively protective fabrics and clothing.     

Texture Development in Modified Lead Titanate Thin Films Obtained by Chemical Solution Deposition on Silicon-Based Substrates

An advanced method of X-ray diffractometry analysis, the quantitative texture analysis, is used in this work to study the preferential orientations of ferroelectric lanthanum-modified lead titanate thin films, to establish the factors affecting their development. The new, more reliable, texture data obtained allows us to discuss previous models of texture development in chemical-solution-deposited films. The results show that a fiber type, mixed <100>,<001> preferential orientation, is obtained when high heating rates are used during crystallization. The degree of texture of these films decreases when successive layers are deposited before a simultaneous crystallization of the ensemble is conducted. This undesirable effect is avoided through layer-by-layer crystallization, because of the preferential nucleation of <100>,<001> crystals at the interface between layers. The use of a titanium layer on the platinized silicon-based substrate leads to the development of an additional fiber <111> texture component. In this case, the layer-by-layer crystallization process cannot avoid the loss of the degree of orientation (texture index) with the increase of film thickness. This is mainly caused by the appearance of interlayer porosity, which disrupts the growth of <111>-oriented grains into upper layers.     

氮化硅薄膜的热丝化学气相沉积法制备及微结构研究

采用热丝化学气相沉积法,以Sill4、NH3、N2为反应气源,通过改变氮气流量沉积氮化硅薄膜.通过紫外-可见(UV-VIS)光吸收谱、傅里叶红外透射光谱(FTIR)、X射线衍射谱(XRD)等测试手段对薄膜的光学带隙、键合特性及晶相进行表征与分析.结果表明:薄膜主要表现为Si-N键合结构,当N2流量从20 sccm变化到40 sccm时,热丝能够充分的分解N2,薄膜中N原子过量,其周围的Si和H能充分的与N结合.但由于N2的解离能较高,当N2流量高于40 sccm时,氮气在反应过程中对薄膜内的氮原子反而起到了稀释作用,薄膜的有序程度增大,光学带隙减小,致密性降低.当氮气流量达到150 sccm时,在2θ为69.5°处出现了晶化β-Si3 N4的尖锐衍射峰,其择优取向沿(322)晶向,且Si3 N4晶粒显著增大.因此,氮气流量对薄膜中的氮含量有显著影响,适当的增加氮气流量有利于制备出优质含有小晶粒β-Si3 N4薄膜.     

化学浴沉积法制备Sb掺杂SnS薄膜

以氯化亚锡、硫代乙酰胺、三氯化锑为反应物,采用化学浴沉积法在玻璃衬底上沉积不同锑掺杂量(摩尔分数)硫化锡(Sn S:Sb)膜,研究了锑掺杂量对薄膜晶相结构、表面形貌和光电性能的影响。结果表明:锑掺杂Sn S薄膜是具有正交结构多晶薄膜,薄膜为纳米片组装成的花状球形颗粒。随着Sb掺杂量由1.8%增加到7.2%,其相应的禁带宽度从0.93 e V增加到1.30 e V。随着Sb掺杂量的增加,Sn S薄膜的电阻率呈现先下降后增大趋势,当Sb掺杂量为3.6%时,其最小值为5.21×103?·cm。     

Lead Zirconate Titanate Thin Films by Aerosol Plasma Deposition: Microstructure Analysis

Lead zirconate titanate (Pb(Zr,Ti)O₃, PZT) thin films were grown on silicon 〈100〉 substrate by aerosol plasma deposition (APD) using solid-state-reacted powder containing donor oxide Nb₂O₅ when keeping the substrate at room temperature and 200°C. Crystalline phases of the deposited films have been analyzed via X-ray diffractometry (XRD), and microstructure via scanning and transmission electron microscopy (SEM and TEM). Cross-sectional TEM revealed that the microstructure comprised several layers including the deposited PZT film and the platinum-electrode-and-titanium-buffered layers on SiO₂–Si substrate. The Pt-electrode layer contained (111)_Pt twinned columnar grains with a slight misorientation and forming low-angle grain boundaries among them. The PZT layer contained randomly oriented grains embedded in an amorphous matrix. Some of the PZT grains, oriented with the zone axis Z = [[Twomacr]11]_PZT parallel to Z = [111]_Pt, were grown epitaxially on the Pt layer by sharing the (111)_PZT plane with the (111)_Pt twinned columnar Pt crystals. However, the existence of such an orientation relationship was confined to several nanosize grains at and near the PZT-Pt interface, and no gross film texture has been developed. An amorphous grain boundary phase, generated by pressure-induced amorphisation (PIA) in the solid state, was identified by high-resolution imaging. Its presence is taken to account for the densification of the PZT thin films via a sintering mechanism involving an amorphous phase on deposition at 25° and 200°C.     

Preparation of a Monodispersed Suspension of Barium Titanate Nanoparticles and Electrophoretic Deposition of Thin Films

A transparent and stable monodispersed suspension of nanocrystalline barium titanate was prepared by dispersing a piece of BaTiO₃ gel into a mixed solvent of 2-methoxyethanol and acethylacetone. The results of high-resolution transmission electron microscopy (HR-TEM) and size analyzer confirmed that the BaTiO₃ nanoparticles in the suspension had an average size of ∼10 nm with a narrow size distribution. Crystal structure characterization via TEM and X-ray diffraction indicated BaTiO₃ nanocrystallites to be a perovskite cubic phase. BaTiO₃ thin films of controlled thickness from 100 nm to several micrometers were electrophoretic deposited compactly on Pt/Ti/SiO₂/Si substrates. The deposited thin film had uniform nanostructure with a very smooth surface.     

堇青石基体化学气相沉积碳化硅薄膜及其性能表征

采用等温等压化学气相沉积技术,分别以CH3SiCl3-H2和SiCl4-CH4-H2为气源,在沉积温度1100和1000℃、压力101 kPa条件下,制备了SiC薄膜. 利用SEM和XRD、显微拉曼光谱、EDAX元素分析、HRTEM等测试技术对沉积薄膜的结构和组成进行了表征. 结果表明,1100℃时,以CH3SiCl3-H2为气源沉积得到纯净的SiC薄膜,以b-SiC (111)面择优定向生长,由微米级的金字塔锥形结构组成,硅含量随着沉积温度降低而增加;以SiCl4-CH4-H2为气源沉积得到非晶态碳掺杂的SiC薄膜,碳含量随着沉积温度降低而增加. 此外,以CH3SiCl3-H2为气源沉积的SiC颗粒平均粒径均比以SiCl4-CH4-H2为气源的粒径大. 前者SiC薄膜的方块电阻在kW级以上,且随着沉积温度的下降急剧升高;后者1100℃时制备的薄膜的方块电阻在kW级以上,且随着沉积温度的降低而急剧下降,1000℃时降低到W级.     

Effect of Deposition Temperature on the Growth of Yttria-Stabilized Zirconia Thin Films on Si(111) by Chemical Vapor Deposition

An experimental study was made on the effect of deposition temperature on the growth of yttria-stabilized zirconia (YSZ) thin films in the chemical vapor deposition (CVD) process. The YSZ thin films were obtained in a temperature range of 650°–850°C, using β-diketone chelates and a Si(111) substrate. Dense and mirrorlike YSZ films with uniform thickness were prepared; the deposition rate was 12–20 nm/min at those temperatures. An examination of the crystalline structure of the YSZ films was made, and the appropriate temperature for the growth of c -axis-oriented YSZ thin films using a Si(111) substrate was determined. The quality of the YSZ films was strongly dependent on the deposition temperature. As the temperature increased, the film growth mechanism changed from being controlled by surface reaction to being controlled by gas-phase diffusion.     

Characterization of Chemical Solution Deposition-Derived Lead Hafnate Titanate Thin Films

In this paper, lead hafnate titanate (PHT) was derived by chemical solution deposition (CSD) and characterized as a thin film material. The thin films were tested for the usage as a ferroelectric thin film in view of Ferroelectric Random Access Memory (FRAM) devices and compared with an equivalent lead zirconate titanate (PZT) thin film, which was prepared under the same conditions. After determining the thickness and the morphology of the PHT films, electronic measurements were performed to investigate this material as a promising candidate in view of FRAM applications due to failure mechanisms like fatigue and imprint.