Deposition Rate Of Films Research Articles

Optical and operational characteristics of diamond-like films deposited using a Hall ion beam source

Data on diamond-like carbon films obtained by deposition from an ion beam formed by a Hall source are presented. The dependences of the film deposition rate on the anode voltage and source current are determined. The ranges of optimal anode current values for the synthesis of antireflective single-layer coatings on germanium and silicon optical elements are found. It is shown that the diamond-like carbon films deposited on both sides of a germanium element ensure a maximum transmittance of 99.6% in the wavelength range of 3–5 μm at a high mechanical strength.

Thin-film lithium batteries with 0.3–30 μm thick LiCoO2 films fabricated by high-rate pulsed laser deposition

High-rate pulsed laser deposition was applied to the preparation of thick LiCoO2 cathode films, which were then used in the fabrication of thin-film batteries. The deposition rate of the LiCoO2 films was 2–3 μm/h. The thin-film batteries showed an increase in capacity up to 470 μAh/cm2 with increasing cathode film thickness. The rate dependence of discharge capacity was analyzed using a diffusion model in which the chemical diffusion coefficient of lithium in the cathode determines the dynamic capacity. For the initial stage of discharge, the chemical diffusion coefficient was estimated to be 10−10 cm2/s. Conversely, the chemical diffusion coefficient decreases to ~10−12 cm2/s at the end of discharge. From the diffusion model, the available capacity was estimated as a function of cathode thickness. Crack formation inside the LiCoO2 film is also suggested as a cause of capacity limitation.

Study on the optimization of the deposition rate of planetary GaN-MOCVD films based on CFD simulation and the corresponding surface model.

Metal-organic chemical vapour deposition (MOCVD) is a key technique for fabricating GaN thin film structures for light-emitting and semiconductor laser diodes. Film uniformity is an important index to measure equipment performance and chip processes. This paper introduces a method to improve the quality of thin films by optimizing the rotation speed of different substrates of a model consisting of a planetary with seven 6-inch wafers for the planetary GaN-MOCVD. A numerical solution to the transient state at low pressure is obtained using computational fluid dynamics. To evaluate the role of the different zone speeds on the growth uniformity, single factor analysis is introduced. The results show that the growth rate and uniformity are strongly related to the rotational speed. Next, a response surface model was constructed by using the variables and the corresponding simulation results. The optimized combination of the matching of different speeds is also proposed as a useful reference for applications in industry, obtained by a response surface model and genetic algorithm with a balance between the growth rate and the growth uniformity. This method can save time, and the optimization can obtain the most uniform and highest thin film quality.

Dependences of deposition rate and OH content on concentration of added trichloroethylene in low-temperature silicon oxide films deposited using silicone oil and ozone gas

We investigated the dependences of the deposition rate and residual OH content of SiO2 films on the concentration of trichloroethylene (TCE), which was added during deposition at low temperatures of 160–260 °C with the reactant gases of silicone oil (SO) and O3. The deposition rate depends on the TCE concentration and is minimum at a concentration of ∼0.4 mol/m3 at 200 °C. The result can be explained by surface and gas-phase reactions. Experimentally, we also revealed that the thickness profile is strongly affected by gas-phase reaction, in which the TCE vapor was blown directly onto the substrate surface, where it mixed with SO and O3. Furthermore, it was found that adding TCE vapor reduces residual OH content in the SiO2 film deposited at 200 °C because TCE enhances the dehydration reaction.

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.

Structural study of epitaxial NdBa2Cu3O7-x films by laser chemical vapor deposition.

Epitaxial NdBa2Cu3O7−x films were prepared on (100) LaAlO3 single crystal substrates by laser chemical vapor deposition (laser CVD). The effect of deposition temperature on preferred orientation, crystallinity, microstructure, deposition rate of films was investigated. The preferred orientation of the NdBCO films changed from a, c-axis to c-axis, then back to a, c-axis, as the deposition temperature was increased from 993 to 1093 K. The highly c-axis-oriented epitaxial NdBa2Cu3O7−x film with critical transition temperature of 87 K was obtained at Tdep = 1033 K, with the in-plane epitaxial orientation relationship of NdBCO [100]∥LAO [010] and NdBCO [010]∥LAO [001]. The growth orientation varied from a-axis to c-axis as the film thickness increased in the case of the a, c-co-oriented NdBCO film. The contribution of thickness-dependent strain relaxation to preferred orientation of the NdBCO films was also discussed.

Normal and grazing incidence pulsed laser deposition of nanostructured MoSx hydrogen evolution catalysts from a MoS2 target

Pulsed laser ablation of a MoS2 target causes enhanced splashing of the material. So, for MoSx films obtained by pulsed laser deposition (PLD) in the conventional normal incidence (NI) configuration, their typical morphology is characterized by an underlying granular structure with an overlayer of widely dispersed spherical Mo and MoSx particles possessing micro-, sub-micro- and nanometer sizes. We investigated the possibility of using high surface roughness, which occurs due to particle deposition, as a support with a large exposed surface area for thin MoSx catalytic layers for the hydrogen evolution reaction (HER). For comparison, the HER performance of MoSx layers formed by grazing incidence (GI) PLD was studied. During GI-PLD, a substrate was placed along the direction of laser plume transport and few large particles loaded the substrate. The local structure and composition of thin MoSx layers formed by the deposition of the vapor component of the laser plume were varied by changing the pressure of the buffer gas (argon, Ar). In the case of NI-PLD, an increase in Ar pressure caused the formation of quasi-amorphous MoSx (x ≥ 2) films that possessed highly active catalytic sites on the edges of the layered MoS2 nanophase. At the same time, a decrease in the deposition rate of the MoSx film appeared due to the scattering of the vapor flux by Ar molecules during flux transport from the target to the substrate. This effect prevented uniform deposition of the MoSx catalytic film on the surface of most particles, whose deposition rate was independent of Ar pressure. The scattered vapor flux containing Mo and S atoms was a dominant source for MoSx film growth during GI-PLD. The thickness and composition distribution of the MoSx film on the substrate depended on both the pressure of the buffer gas and the distance from the target. For 1.0–2.5 cm from the target, the deposition rate was quite sufficient to form S-enriched quasi-amorphous MoSx (2.5 < x < 6) catalytic films that consisted of densely packed 30–50 nm nanoparticles. The GI-PLD films possessed a greater density of catalytically active sites with a distinct local atomic configuration including edge sites of the layered MoS2 nanophase and diverse S ligands in the amorphous phase, which contained Mo3-S clusters. At a modest loading of ∼300 μg/cm2 on glassy carbon substrates and an overpotential of -140 mV, these films activated H2 production with geometric current densities up to −10 mA/cm2.

Stability and process parameter optimization for a vertical rotating ZnO-MOCVD reaction chamber

Developing an understanding of the cavity stability underlying the metalorganic chemical vapor deposition (MOCVD) of ZnO is critical to the fabrication of oxide-based devices. Therefore, computational fluid dynamics (CFD) was used to study the process parameters (e.g., the growth temperature, total gas flow, chamber pressure, and substrate speed) of the MOCVD H-type reaction chamber for four states in the cavity: buoyancy-induced flow, plug flow, rotating-plug flow, and rotating flow. Based on these states, criteria for determining stable and unstable flows were determined. These can be presented on the pressure–rotation rate spectrum, which can be used to visualize the effects of specific process parameters on the flow stability. In order to obtain a good film deposition rate in the stable flow state of the cavity, a response surface model and genetic algorithm were also used to optimize the process parameters. The coefficient of variation of the optimized ZnO film was reduced to 2%, which greatly improved the film quality. This study provides a comprehensive insight into the transport phenomena of the MOCVD H-type reaction chamber, including coupled heat and mass transfer and chemical reactions, and presents the optimal combination of parameters to provide a useful reference for obtaining high-quality thin films.

Measurements and modeling of the impact of radical recombination on silicon nitride growth in microwave plasma assisted atomic layer deposition

High material quality silicon nitride thin film deposition by plasma enhanced atomic layer deposition (PEALD) is necessary for many advanced semiconductor device and memory fabrication applications. Understanding film growth mechanism is quite important not only for the device production control but also device performance due to the strong correlation of film growth speed and film chemical property. Nevertheless, predicting film deposition rates, let alone film quality, is difficult as quantitative surface reaction mechanisms are still not well known and the species fluxes that play the central role in film growth are not easy to measure. In this paper, the authors describe how a plasma reactor model for the nitridation step required in PEALD of silicon nitride can be combined with a phenomenological site balance model to predict film growth rate variation with some key process parameters. The relative insensitivity of growth rates to plasma power are explained by competing destruction and regeneration mechanisms for NH3, an important nitrogen source in Si3N4 growth. The model also helps to reveal why H2 can be important.

Superimposed high power impulse and middle frequency magnetron sputtering: Role of pulse duration and average power of middle frequency

The low deposition rate of the high power impulse magnetron sputtering (HiPIMS) somewhat limits its commercial applications in thin film and coating industries. In this work, an effective way to improve the deposition rate of TiN film by superimposing the middle-frequency (MF) pulses during off-time of HiPIMS pulsing was discussed. Superimposition of HiPIMS and MF fabricated TiN films with relatively smooth surface. All samples were found to have a single phase TiN according to the chemical composition and crystallographic analyses. The highest film hardness of ~31GPa, elastic modulus of 313GPa, and a density of 5.35g/cm3 were obtained in the sample grown at a MF pulse duration of 150μs in each superimposed cycle. The higher the deposition rate was achieved with longer MF pulse duration. This superimposition technique successfully improved the power-normalized deposition rate from 4.5 to 17.2nm/kW·min without significantly declining the mechanical properties and adhesion quality of deposited films. The role of MF pulse duration and average MF power were further studied in this work. It can be concluded that the MF pulse duration played a more significant role and showed a dominant influence on the plasma characteristics and resulting properties of deposited TiN films.

Angular Dependence of Si3N4 Etching in C4F6/CH2F2/O2/Ar Plasmas

AbstractThe dependence of Si3N4 etching on ion‐incident angles is investigated at various CH2F2 flow rates in C4F6/CH2F2/O2/Ar plasmas. The normalized etch yield (NEY) curves for Si3N4 imply that physical sputtering is a major contributor to Si3N4 etching. An increase in the amount of CH2F2 in the plasma produces thicker and more etch‐resistant fluorocarbon films. Systematic analyses on deposition and etching of the passively deposited fluorocarbon films on Si3N4 in a C4F6/CH2F2/O2/Ar plasma show that the normalized deposition rate of the fluorocarbon film is nearly the same and unaffected by the CH2F2 flow rate while etching of fluorocarbon films is similar to etching of Si3N4, thus, etching of the fluorocarbon film, rather than its deposition, limits Si3N4 etching in C4F6/CH2F2/O2/Ar plasmas.

Modular injector integrated linear apparatus with motion profile optimization for spatial atomic layer deposition

A spatial atomic layer deposition apparatus integrated with a modular injector and a linear motor has been designed. It consists of four parts: a precursor delivery manifold, a modular injector, a reaction zone, and a driving unit. An injector with multi-layer structured channels is designed to help improve precursor distribution homogeneity. During the back and forth movement of the substrate at high speed, the inertial impact caused by jerk and sudden changes of acceleration will degrade the film deposition quality. Such residual vibration caused by inertial impact will aggravate the fluctuation of the gap distance between the injector and the substrate in the deposition process. Thus, an S-curve motion profile is implemented to reduce the large inertial impact, and the maximum position error could be reduced by 84%. The microstructure of the film under the S-curve motion profile shows smaller root-mean-square and scanning voltage amplitude under an atomic force microscope, which verifies the effectiveness of the S-curve motion profile in reducing the residual vibration and stabilizing the gap distance between the injector and the substrate. The film deposition rate could reach 100 nm/min while maintaining good uniformity without obvious periodic patterns on the surface.

Effects of PECVD temperature and RF power on surface structure and refractive index of amorphous and polycrystalline silicon films

The amorphous and polycrystalline silicon films were obtained by plasma enhanced chemical vapor deposition. The effect of power and temperature over a wide range on the surface morphology and structure, deposition rate films and refractive index have been investigated by atomic force microscopy, profilometry and ellipsometry. The deposition rate increased from 19.1 to 58.2 nm/min with RF power from 10 to 40 W. The refractive index of the films obtained at a temperature of 550 to 700 °C was in the range from 3.5 to 5.5.

Influence of texture on the electrical properties of Al-doped ZnO films prepared by ultrasonic spray pyrolysis

ZnO: Al thin films were deposited by spray pyrolysis onto glass substrates with 0, 0.5, 1.0, 2.0, 5.0 and 10.0% [Al3+/Zn2+] ratios in the deposition solution. Films were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, UV–vis transmittance, conductive atomic force microscopy and the sheet resistance was measured. Aluminum contents in the films increases with the Al3+/Zn2+ ratio in the bath while the film deposition rate decreases due to the lower Al3+ surface mobility. Films were crystalline and display a varied morphology that evolves from flakes to mixtures between flakes and pencils and finally between triangles and hexagonal columns with increasing Al contents. Al3+ inclusion at the different sites within the ZnO lattice is proposed to direct the crystal habit and therefore the observed morphology and film texture. The optical band gap evolution and carrier density are related by the Burstein-Moss effect. The results show that film texture influences carrier mobility: increased presence of (112) planes originate a mobility increase while a predominant (110) or (100) texture reduces it. By Current sensing Atomic Force Microscopy (CAFM) the local surface current distribution was related with the observed film texture.

Magnetic Field Resonance and Pressure Effects on Epitaxial Thin Film Deposition and In Situ Plasma Diagnostics

This study demonstrated the use of quadrupole mass spectrometry and optical emission spectrometry in diagnosing the plasma in the electron cyclotron resonance chemical vapor deposition (ECRCVD) process. The effects of adjusting the main magnetic coil current and process pressure on chemical composition of the plasma and the characteristics of the epitaxial thin film in the ECRCVD system were investigated. When the main magnetic coil current increased, the deposition rate of thin film increased, with no major effect on thin film crystallization. However, when the process pressure was higher, both the deposition rate and crystallization of epitaxial thin film increased.

Electrical Conduction and Mechanism of Zinc Oxide Thin Films with Different Types and Levels of Defects

ABSTRACTIn this work, the electrical conducting and mechanism of zinc oxide thin films with different types and levels of defects were investigated. The films were deposited by radio frequency magnetron sputtering sintered zinc oxide ceramic target under an atmosphere at different partial pressure ratios of O2 to Ar gases (O2/Ar ratio). Under the designed deposition conditions, all the prepared films were of wurtzite structure with a preferential growth orientation of c axis. With increasing O2/Ar ratio, the film thickness, deposition rate and grain size decreased, and the content of Zn in the films initially decreased and then increased. When the O2/Ar ratio was lower than 0.5, the dominant defects in the films were oxygen vacancies; when it was higher than 0.5, the main defects were interstitial zinc; but with an appropriate O2/Ar ratio of 0.5, the film composition may approach to the stoichiometric ZnO, which had the least number of defects. Resultantly, with increasing O2/Ar ratio, the electrical resistivity of the films initially increased and then decreased.

Chemical bath deposited ZnS buffer layer for Cu(In,Ga)Se2 thin film solar cell

The dependence of Zn precursors using zinc sulfate (ZnSO4), zinc acetate (Zn(CH3COO)2), and zinc chloride (ZnCl2) on the characteristics of the chemical bath deposited ZnS thin film used as a buffer layer of Cu(In,Ga)Se2 (CIGS) thin film solar cell was studied. It is found that the ZnS film deposition rate increases with higher stability constant during decomplexation reaction of zinc ligands, which affects the crack formation and the amount of sulfur and oxygen contents within the film. The band gap energies of all deposited films are in the range of 3.40–3.49eV, which is lower than that of the bulk ZnS film due to oxygen contents within the films. Among the CIGS solar cells having ZnS buffer layers prepared by different Zn precursors, the best cell efficiency with 9.4% was attained using Zn(CH3COO)2 precursor due to increased Voc mainly. This result suggests that [Zn(NH3)4]2+ complex formation should be well controlled to attain the high quality ZnS thin films.

Influences of target poisoning on the mechanical properties of TiCrBN thin films grown by a superimposed high power impulse and medium-frequency magnetron sputtering

Five TiCrBN coatings have been successfully fabricated by adopting hybrid co-deposition and superimposition concepts into high power impulse magnetron sputtering. The medium-frequency (MF) pulses were superimposed during the off-time of HiPIMS pulsing to Ti target. The direct-current (DC) and radio-frequency (RF) powers were connected to TiB2 and Cr targets, respectively. A plasma emission monitoring (PEM) system was used to grow thin films by tailoring the Ti target in transition and poisoning regimes, respectively. The different PEM set points, i.e., different target transition or poisoned regions, were selected to study their effects on the properties of deposited TiCrBN film. The deposition rate of TiCrBN films increased 1.64 times higher when the Ti target status changed from poisoning to transition regime by selecting PEM set points tuning from 30% to 70%. All samples exhibited a fine and dense microstructure, and a very smooth surface with the average roughness <1nm. The coefficient of friction and wear rate of each coating were in the ranges of 0.47–0.58 and 1.59–9.82×10−6mm3N−1m−1, respectively. The highest hardness of 38.9GPa, elastic modulus of 374GPa, acceptable adhesion quality of HF3 and upper critical load of 30N were obtained for T50% sample, which was grown at the PEM set point of 50%, in the transition region of Ti target and under the highest HiPIMS peak power density. This study also demonstrates the potential application of PEM apparatus attached to a superimposed HiPIMS-MF deposition technique for tailoring the growth of multicomponent metal nitride hard coatings.

Deposition of silicon oxycarbide thin films from an organosilicon source for polycarbonate glazing

To enhance the abrasion resistance of polycarbonate used to replace glass, a silicon oxycarbide thin film was deposited at <100°C using a slot antenna electron cyclotron resonance plasma enhanced chemical vapor deposition system and an organosilicon source. The thin film deposition rate, which varied as a function of microwave power and whether Ar or O2 was used to form the plasma, was above 500nm/min even at 2Pa, and reached 1μm/min as the microwave power increased. The transmittance of visible light was over 90% after thin film deposition, indicating performance similar to that of glass. The Taber abrasion test showed that the Δhazes of the thin films were under 5%, which indicates better performance than the siloxane-based wet coating sample (Momentive, AS4700) and the commercial hard plasma coating product LEXAN MR-10. Furthermore, the thin film deposited at 1.7kW exhibited similar abrasion resistance to that of glass. In addition, adhesion improved significantly when consecutive, minute-long 1.7kW Ar and O2 plasma surface treatments were performed before the depositions.

Control of composite thin film made in an Ar/isopropanol/TiO2 nanoparticles dielectric barrier discharge by the excitation frequency

The synthesis of composites thin films made by injecting an aerosol suspension of 20 nm‐size TiO2 nanoparticles (NPs) and isopropanol (IPA) in a filamentary argon Dielectric Barrier Discharge (DBD) is studied as a function of the DBD frequency from 1 to 50 kHz. The plasma is modulated to get homogeneous coatings. The deposition rate and morphology of the composite thin films are determined from SEM images of both surface and cross section. Their chemical composition is investigated by XPS, Raman spectroscopy and FTIR measurements. The structural composition of the NPs is examined by XRD. All the deposited composites show the chemical signature of the NPs as well as of the polymer‐like coating resulting from the plasma polymerization of IPA. No mixed phase is observed and the sizes of the NPs as well as of their aggregates are not affected by the plasma. With this method aerosol droplets are evaporated before entering the plasma and the NPs inside a same droplet are aggregated. Results show that the DBD frequency controls the composite composition by independently influencing the NPs transport and the matrix growth rate. At 1 kHz, the coating is essentially made of NPs with a low carbon coating. From 1 to 50 kHz, the Ti/C ratio is divided by two orders of magnitude. As the frequency increases the quantity of NPs decreases and since 10 kHz the matrix thickness increases. The decrease of the NPs is explained by the numerical modeling of the NPs trajectory. It is found that from 10 to 1 kHz, the lower is the frequency, the higher is the transport of the NPs to the surface due to the electrostatic force. On the other hand the matrix growth rate increases from almost zero at 10 kHz up to 19 nm · min−1 at 50 kHz because of the linear increases of the DBD power with the frequency.