Film Deposition Process Research Articles

Investigation of arc spot splitting behavior on aluminum, titanium, and their alloy cathodes under different gas flows

This paper presents an experimental study on the spot splitting behavior of aluminum, titanium, and their alloy cathodes during electric arc discharge. Utilizing high-speed digital cameras, we dynamically captured the splitting motion of cathode arc spots and analyzed their behavior under different pressures of argon, nitrogen, and oxygen. The study also examined the effects of pulsed arc current parameters on spot splitting. We observed a ringlike expansion of pulsed arc spots during splitting, with aluminum cathodes showing better performance than titanium in promoting spot splitting and stabilizing the subsequent motion of the split spots. Oxygen was found to enhance spot splitting more effectively than nitrogen. Furthermore, the parameters of the pulsed arc can control the extent of spot splitting and expansion. These findings provide valuable insights for optimizing arc parameter control in metal film deposition processes.

Study on oil film spreading characteristics on the jet lubricating tooth surface of aviation herringbone gear

Purpose During the oil lubrication process of aviation herringbone gears, lubricating oil is injected into and spreads around the tooth surface. Its spreading characteristics directly affect the lubrication state and transmission efficiency of gears. This study aims to investigate the effect of changing the injection parameters and gear operating conditions on the oil film deposition during injection lubrication. Design/methodology/approach The computational fluid dynamics method was used to establish the computational domain for the simulation and optimization using an orthogonal test. The oil film spreading and thickness of the tooth surface were calculated with the change in gear speed, fuel injection distance and fuel injection speed. Optimized oil injection lubrication parameters were obtained, and design ideas were provided for the oil injection lubrication analysis of aviation herringbone gears. Findings Under different operating conditions, such as varying the injection speed, gear rotational speed and injection distance, there were differences in the distribution of the lubricating oil film formed on the tooth surface. The thickness of the oil film decreases as the distance from the injection port increases. The thickness of the oil film deposition can be increased by increasing the injection velocity and reducing the gear rotation speed. The injection distance had a relatively small effect on the spreading thickness of the deposited oil film, affecting only the dynamic spreading process of oil film deposition. Furthermore, the simulation results are compared with the analytical calculation results, and finally the experimental verification is carried out. Originality/value Oil spray lubrication characteristics are important for achieving precise gear lubrication designs in the aerospace field. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2023-0250/

Effect of RF acetylene plasma on the composition and dynamics of a titanium plasma plume in a plasma enhanced pulsed laser deposition system

We report the effect of radio frequency (RF) acetylene plasma on the dynamics and composition of titanium (Ti) plasma plume in a plasma-enhanced pulsed laser deposition (PEPLD) system. The titanium target, mounted inside a capacitively coupled RF discharge, was ablated by using a nanosecond Nd:YAG pulsed laser at 1064 nm with a power density of 2.65 GW/cm2. The experiments were performed at different operating pressures of acetylene. Fast imaging and optical emission spectroscopy were employed to study the physics behind the pulsed laser deposition in both (PLD) and PEPLD systems. A nonlinear dependence of the plasma plume evolution was observed over a range of pressure. Different expansion regimes correspond to the pressure of the experiments. The plume expansion velocity ranges between 6 × 103 m/s and 30 × 103 m/s. Emission spectra reveal the presence of C II and Ti II lines depending on the experimental conditions. The presence of background RF plasma leads to substantial enhancement of the emission intensity of the C II spectral lines. In addition, with increasing RF power and background pressure, the intensities of the C II spectral lines increase; whereas the intensities of the Ti II spectral lines decrease with the increase in RF power. Plasma temperature was estimated from the Ti II lines using the Boltzmann plot method, whereas the electron density was estimated from the Stark-broadened Ti II line at 454.9 nm. The calculated densities and temperatures lie between 1017–1018 cm−3 and 0.8–2.0 eV, respectively. These results show the effects of the different backgrounds (either neutral or RF plasma) on the propagation of the laser-produced plasma (LPP), which we propose to be useful in the thin film deposition process using PLD.

Stress-Dependent Optical Extinction in Low-Pressure Chemical Vapor Deposition Silicon Nitride Measured by Nanomechanical Photothermal Sensing.

Understanding optical absorption in silicon nitride is crucial for cutting-edge technologies like photonic integrated circuits, nanomechanical photothermal infrared sensing and spectroscopy, and cavity optomechanics. Yet, the origin of its strong dependence on the film deposition and fabrication process is not fully understood. This Letter leverages nanomechanical photothermal sensing to investigate optical extinction κext at a 632.8 nm wavelength in low-pressure chemical vapor deposition (LPCVD) SiN strings across a wide range of deposition-related tensile stresses (200-850 MPa). Measurements reveal a reduction in κext from 103 to 101 ppm with increasing stress, correlated to variations in Si/N content ratio. Within the band-fluctuations framework, this trend indicates an increase of the energy bandgap with the stress, ultimately reducing absorption. Overall, this study showcases the power and simplicity of nanomechanical photothermal sensing for low absorption measurements, offering a sensitive, scattering-free platform for material analysis in nanophotonics and nanomechanics.

Molecular Dynamics Study of Substrate Temperature and Incident Energy Influence on the Crystallization Behavior of Alumina Thin Film Deposition Process

Molecular Dynamics Study of Substrate Temperature and Incident Energy Influence on the Crystallization Behavior of Alumina Thin Film Deposition Process

Layer-by-layer assembly of a [Fe-(pyrazine){Pd(CN)4}] spin crossover thin film.

[Fe-(pyrazine){Pd(CN)4}] (pyrazine = pz) thin films were fabricated using a layer-by-layer assembly approach, a method known to be tunable, versatile, and scalable, since thin films are better-suited for industrial applications. In this study, [Fe-(pz){Pd(CN)4}] powder was synthesized, and the results obtained from a vibrating sample magnetometer verified the presence of an abrupt hysteresis loop with widths of 45 K centered around 300 K, indicating good cooperativity. Super conducting quantum interference device magnetometry results indicated a slow spin transition with temperature but with evidence of hysteresis for thin film samples. X-ray absorption analysis provided further support of the spin crossover behavior but differs from the magnetometry because the spin state transition at the surface differs from the bulk of the thin film. X-ray photoelectron spectroscopy provided some insight into issues with the film deposition process and multiplex fitting was used to further support the claim that the surface of the film is different than the bulk of the film.

Understanding vapor phase growth of hexagonal boron nitride.

Hexagonal boron nitride (hBN), with its atomically flat structure, excellent chemical stability, and large band gap energy (∼6 eV), serves as an exemplary 2D insulator in electronics. Additionally, it offers exceptional attributes for the growth and encapsulation of semiconductor transition metal dichalcogenides (TMDCs). Current methodologies for producing hBN thin films primarily involve exfoliating multi-layer or bulk crystals and thin film growth via chemical vapor deposition (CVD), which entails the thermal decomposition and surface reaction of molecular precursors like ammonia boranes (NH3BH3) and borazine (B3N3H6). These molecular precursors contain pre-existing B-N bonds, thus promoting the nucleation of BN. However, the quality and phase purity of resulting BN films are greatly influenced by the film preparation and deposition process conditions that remain a substantial concern. This study aims to comprehensively investigate the impact of varied CVD systems, parameters, and precursor chemistry on the synthesis of high-quality, large scale hBN on both catalytic and non-catalytic substrates. The comparative analysis provided new insights into most effective approaches concerning both quality and scalability of vapor phase grown hBN films.

First-Principles computation-driven mechanism study of tungsten growth on alumina surfaces with TiN nano-islands

Strong comprehension of the tungsten film deposition process on Al2O3 substrate with TiN adhesion layer is essential to achieve high quality metal gate, but the fundamental mechanism of this process is yet to be fully understood. This study employs first-principles density functional theory (DFT) calculations to explore the mechanisms of tungsten film growth on alumina surfaces while focusing on amorphous/α-Al2O3 and interfaces with TiN nano-islands. Tungsten atoms are strongly bonded on the Al2O3/TiN interface compared to their bonding on the Al2O3 or TiN surface, regardless of the crystallinity of Al2O3. Moreover, amorphous Al2O3 surfaces exhibit stronger adsorption energies and present higher diffusion barriers for tungsten atoms compared to their crystalline counterparts, α-Al2O3, and TiN surfaces, which were also confirmed by electronic structure analysis. This enhanced adhesion on amorphous substrates suggests a potential pathway through which improve the step coverage and uniformity of tungsten thin films while addressing common issues such as void formation and non-uniform layering in high-aspect-ratio structures. Post-deposition annealing can help create crystalline tungsten films with superior conductivity. The insights gained from this work offer a computational perspective on the atomic-level interactions governing tungsten deposition, and they are expected to help producing high-quality thin films in semiconductor technologies.

Exploring negative ion behaviors and their influence on properties of DC magnetron sputtered ITO films under varied power and pressure conditions

Abstract We deposited indium-tin-oxide (ITO) films on silicon and quartz substrates by magnetron sputtering technology in pure argon. Using electrostatic quadrupole plasma diagnostic technology, we investigate the effects of discharge power and discharge pressure on the ion flux and energy distribution function of incidence on the substrate surface, with special attention to the production of high-energy negative oxygen ions, and elucidate the mechanism behind its production. At the same time, the structure and properties of ITO films are systematically characterized to understand the potential effects of high energy oxygen ions on the growth of ITO films. Combining with the kinetic property analysis of sputtering damage mechanism of transparent conductive oxide (TCO) thin films, this study provides valuable physical understanding of optimization of TCO thin film deposition process.

Effects of Rapid Heat Treatments on the Properties of Cu2O Thin Films Deposited at Room Temperature Using an Ammonia-Free SILAR Technique

We report herein the analysis of the properties of copper(I) oxide thin films deposited by an optimized ammonium-free successive ion layer adsorption and reaction (SILAR) technique. The Cu2O thin film deposition process was carried out at room temperature using copper acetate monohydrate, sodium citrate as complexing agent, and hydrogen peroxide as precursors of copper and oxygen ions, respectively. The harmless and easy-to-handle sodium citrate replaces the volatile NH4OH commonly employed as complexing agent in the SILAR technique for the deposition of metal oxide thin films. The optical, structural, morphological, and electrical properties of the as-deposited Cu2O thin films were studied as a function of the number of cycles during deposition, as well as their modifications produced by the effect of rapid thermal annealing (RTA) in vacuum in a temperature range of 200–250°C for 1 min, 3 min, and 5 min. The as-deposited thin films had cubic crystalline structure corresponding to the Cu2O phase as determined by x-ray diffraction (XRD), with a direct energy bandgap of 2.43–2.51 eV depending on the number of cycles, and electrical resistivity of the order of 103 Ω cm. The XRD and x-ray photoelectron spectroscopy (XPS) analysis of the Cu2O thin films treated by RTA demonstrated an increase of the crystal size with time and temperature of the RTA and reduction effects from Cu2+ to Cu1+ oxidation states. On the other hand, the RTA treatments also decreased their energy bandgap to 2.38 eV and electrical resistivity to 102 Ω cm. The high energy bandgap values of the Cu2O thin films were attributed to quantum confinement effects produced by their small crystal size in the range of 3.6–8.6 nm.Graphical

Atomic Layer Deposition of Molybdenum Carbide Thin Films

AbstractThe development of deposition processes for metal carbide thin films is rapidly advancing, driven by their potential for applications including catalysis, batteries, and semiconductor devices. Within this landscape, atomic layer deposition (ALD) offers exceptional conformality, uniformity, and thickness control on spatially complex structures. This paper presents a comprehensive study on the thermal ALD of MoCx with MoCl5 and 1,4‐bis(trimethylgermyl)‐1,4‐dihydropyrazine [(Me3Ge)2DHP] as precursors, focusing on the functional properties and characterization of the films. The depositions are conducted at 200–300 °C and very smooth films with RMS Rq ≈0.3–0.6 nm on Si, TiN, and HfO2 substrates are obtained. The process has a high growth rate of 1.5 Å cycle−1 and the films appear to be continuous already after 5 cycles. The films are conductive even at thicknesses below 5 nm, and films above 18 nm exhibit superconductivity up to 4.4 K. In lieu of suitable references, Raman modes for molybdenum carbides and nitrides are calculated and X‐ray diffraction and X‐ray photoelectron spectroscopy are used for phase analysis.

A Systematic Review of the Trends Thin Film Characteristics Research as Electronic Device (2015-2024)

Thin film characteristics are the properties possessed by the thin film, both physical and chemical properties. The characteristics of this thin film are influenced by several factors, namely the material that makes up the thin film, the thin film deposition method, and the conditions of the thin film deposition process. This research aims to identify and analyze research trends in the characteristics of thin films as electronic devices. This research method is descriptive and analytical. The data used in this research was obtained from documents indexed by Google Scholar from 2015-2024 using Publish or Perish and Dimension.ai. Research procedures use PRISMA guidelines. The data identified and analyzed are the type of publication, publication source, and the title of research on thin film synthesis that is widely cited. The data analysis method uses bibliometric analysis assisted by VOSviewer software. The results of the analysis show that the trend of research on the characteristics of thin films as electronic devices indexed by Google Scholar from 2015 to 2024 experienced a fluctuating increase, however, in 2023 there was a decline in the trend of research on the characteristics of thin films as electronic devices. There are many documents in the form of articles, proceedings, book chapters, preprints, and edited books that discuss research into the characteristics of thin films as electronic devices. Key words that are often used in research on the characteristics of thin films as electronic devices are thin film coating, heat transfer characteristic, film characteristic, and photovoltaic characteristic.

Study on Ion Flux From Magnetically Confined Low-Pressure Arc Discharge With a Thermionic Cathode to Substrate for High-Throughput Film Deposition Processes

Study on Ion Flux From Magnetically Confined Low-Pressure Arc Discharge With a Thermionic Cathode to Substrate for High-Throughput Film Deposition Processes

A systematic review of the trends thin film characteristics research as electronic device (2015-2024)

Thin film characteristics are the properties possessed by the thin film, both physical and chemical properties. The characteristics of this thin film are influenced by several factors, namely the material that makes up the thin film, the thin film deposition method, and the conditions of the thin film deposition process. This research aims to identify and analyze research trends in the characteristics of thin films as electronic devices. This research method is descriptive and analytical. The data used in this research was obtained from documents indexed by Google Scholar from 2015-2024 using Publish or Perish and Dimension.ai. Research procedures use PRISMA guidelines. The data identified and analyzed are the type of publication, publication source, and the title of research on thin film synthesis that is widely cited. The data analysis method uses bibliometric analysis assisted by VOSviewer software. The results of the analysis show that the trend of research on the characteristics of thin films as electronic devices indexed by Google Scholar from 2015 to 2024 experienced a fluctuating increase, however, in 2023 there was a decline in the trend of research on the characteristics of thin films as electronic devices. There are many documents in the form of articles, proceedings, book chapters, preprints, and edited books that discuss research into the characteristics of thin films as electronic devices. Key words that are often used in research on the characteristics of thin films as electronic devices are thin film coating, heat transfer characteristic, film characteristic, and photovoltaic characteristic.

Run-indexed time-varying Bayesian optimization with positional encoding for auto-tuning of controllers: Application to a plasma-assisted deposition process with run-to-run drifts

Bayesian optimization (BO) has emerged as a useful paradigm for automatic calibration (aka auto-tuning) of advanced optimization- and learning-based controllers whose closed-loop performance depends on the choice of several tuning parameters in highly nonlinear and nonconvex ways. However, BO approaches to controller auto-tuning commonly rely on the assumption that system dynamics remain constant, which does not hold for systems with time-varying dynamics, for example, due to gradual aging or persistent environmental drifts. This challenge can be further compounded when gradual and persistent system drifts occur over a series of process runs. Existing time-varying BO (TVBO) approaches with spatio-temporal kernels fall short of effectively handling an integer run index, which is imperative for capturing run-to-run changes in the system behavior. To this end, this paper presents a run-indexed TVBO (RI-TVBO) approach that can systematically account for run-to-run process drifts as the system is queried over sequential process runs. The proposed approach relies on adapting the non-stationary Wiener process kernel to accommodate an integer run index, instead of time. This is done via positional encoding that incorporates the integer run index and, thus, enables describing run-to-run variations in system dynamics. The positional embedding vector associated with each run index is then mapped onto a scalar value to leverage the relationships between different process runs within the probabilistic surrogate model of the objective function in RI-TVBO. The performance of RI-TVBO is evaluated for auto-tuning of an offset-free model predictive controller for a low-temperature plasma-assisted process for thin film deposition. Simulation results demonstrate the superior performance of RI-TVBO over standard BO and TVBO under different scenarios of run-to-run process drifts encountered in plasma-assisted deposition processes in semiconductor manufacturing.

Spider Silk/Hemin Biobased Electrets for Organic Phototransistor Memory: A Comprehensive Study on Solution Process Engineering

AbstractThe escalating environmental impact of pollution and the imperative to reduce carbon emissions have heightened the significance of developing biobased materials from natural biomass for electronic devices. This study investigates the utilization of biofermentation‐produced recombinant spider silk and animal‐derived hemin to create a novel biobased electret for field‐effect transistor memory. A critical challenge arises from the incompatibility between natural photoresponsive molecules and insulating biomaterials, resulting in severe phase separation that compromises film quality and morphology uniformity. This study systematically examines the effects of various film deposition and manufacturing techniques on the biobased electret's morphology, phase separation, and performance. Different methods demonstrate distinct advantages in terms of molecular aggregation/segregation, morphological homogeneity, and device performance. Phototransistor memory devices fabricated using spin coating and spray coating techniques exhibit robust aggregations and high memory windows of ≈30 V. Conversely, devices produced through solution shearing and electrospinning methods display enhanced smooth morphologies and high photoresponsivity. The phototransistor memory comprising electrospun fibers holds the potential to achieve the highest memory ratio, reaching ≈105. These findings not only highlight the applications of biobased materials through scalable film deposition processes but also underscore the importance of refining their morphology, phase separation, and performance in optoelectronic devices.

Co‐Evaporated CuSbSe2 Thin Films for Solar Cells

CuSbSe2 is a promising light‐harvesting material for solar cells, which shows advantages including low melting point, low cost, and environmental friendliness, as well as excellent optoelectronic properties. In this work, a three‐source co‐evaporation method is employed to deposit CuSbSe2 thin films for the first time. Well‐crystallized and pure‐phase CuSbSe2 films are obtained through a two‐stage co‐evaporation, and the reaction mechanism of CuSbSe2 is revealed based on the phase evolution during film deposition process. It is also found that the growth atmosphere during the high‐temperature stage of co‐evaporation deposition exerts a significant impact on the phase, composition, crystallinity, and optoelectronic properties of CuSbSe2 films. Eventually, a Mo/CuSbSe2/CdS/ZnO:Al (AZO)/Ag‐structured solar cell is successfully constructed, yielding a considerable power conversion efficiency of 1.83%.

Modelling the growth reaction pathways of zincone ALD/MLD hybrid thin films: a DFT study.

ALD/MLD hybrid thin films can be fabricated by combining atomic layer deposition (ALD) and molecular layer deposition (MLD). Even though this deposition method has been extensively used experimentally, the computational work required to acquire the reaction paths during the thin film deposition process is still in dire demand. We investigated hybrid thin films consisting of diethyl zinc and either 4-aminophenol or hydroquinone using both gas-phase and surface reactions to gain extensive knowledge of the complex phenomena occurring during the process of hybrid thin film deposition. We used density functional theory (DFT) to obtain the activation energies of these kinetic-dependent deposition processes. Different processes of ethyl ligand removal as ethane were discovered, and we found that the hydroxyl group of 4-aminophenol was more reactive than the amino group in the migration of hydrogen to an ethyl ligand within a complicated branching reaction chain.

Numerical optimization of dielectric properties to achieve process uniformity in capacitively coupled plasma reactors

This paper presents the results of our numerical analysis to optimize the dielectric properties to achieve process uniformity in the thin film deposition process using capacitively coupled plasma. The difference in the plasma density distribution was analyzed by changing the wafer material from silicon to quartz (or Teflon). Similarly, aluminum was compared with aluminum nitride as the electrode material, and the sidewall material was varied from quartz to a perfect dielectric to study the effect on the plasma characteristics. A two-dimensional self-consistent fluid model was used to analyze the spatial distribution of the plasma parameters. In terms of the process conditions, the gas pressure was set to 400 Pa, the input power was fixed to 100 W, and a radio frequency of 13.56 MHz was used. SiH4/Ar was used as the gas mixture, and these conditions were used as input for numerical simulations of the deposition state of the hydrogenated amorphous silicon layer. The radial spatial distribution of plasma parameters was confirmed to be modified by dielectric elements with low dielectric constants regardless of the type of element. Despite the thin wafer thickness, the use of a wafer with low permittivity weakens the electric field near the electrode edge due to the stronger surface charging effect. Additionally, by changing the material of the sidewall to a perfect dielectric, a more uniform distribution of plasma could be obtained. This is achieved as the peak values of the plasma parameters are located away from the wafer edge. Interestingly, the case in which half of the sidewall was specified as comprising a perfect dielectric and the other half quartz had a more uniform distribution than the case in which the sidewalls consisted entirely of a perfect dielectric.

Ultraviolet-Visible Absorption Spectroscopy of MoCl5, MoOCl4, and MoO2Cl2 Vapors.

This article reports quantitative absorption spectra for MoCl5, MoOCl4, and MoO2Cl2 in the vapor phase from 45,500 to 15,500 cm-1 (645 to 220 nm). Spectra are obtained in an ultrahigh purity stainless steel vacuum system by rapidly sampling a range of analyte partial pressures. The short measurement times and the differential absorbance method employed here minimize effects from uncontrolled transients such as window deposits. A detailed analysis of replicate measurements and time-resolved spectra shows generally reproducible spectral response from MoCl5 vapors at 120 °C. The presence of HCl and MoOCl4 impurities in the MoCl5 vapor samples is determined to be unlikely based on the analysis of absorbance-pressure curves and spectral peak fitting. Comparison with MoOCl4 and MoO2Cl2 spectra shows a unique spectral fingerprint for MoCl5 at 28,500 cm-1 providing a convenient means of discriminating between MoCl5 and its oxychlorides in the visible wavelengths. Adsorption behavior of MoCl5 on surfaces is also discussed with particular emphasis on the use of MoCl5 as a reactant in vapor phase thin film deposition processes.