Deposition Of SiO2 Thin Films Research Articles

Non-destructive processing of silver containing glass ceramic antibacterial coating on polymeric surgical mesh surfaces.

Surgical meshes composed of bioinert polymers such as polypropylene are widely used in millions of hernia repair procedures to prevent the recurrence of organ protrusion from the damaged abdominal wall. However, post-operative mesh infection remains a significant complication, elevating hernia recurrence risks from 3.6% to 10%, depending on the procedure type. While attempts have been made to mitigate these infection-related complications by using antibiotic coatings, the rise in antibiotic-resistant bacterial strains threatens their effectiveness. Bioactive glass-ceramics featuring noble metals, notably silver nanoparticles (AgNPs), have recently gained traction for their wide antibacterial properties and biocompatibility. Yet, conventional methods of synthesizing and coating of such materials often require high temperatures, thus making them impractical to be implemented on temperature-sensitive polymeric substrates. To circumvent this challenge, a unique approach has been explored to deposit these functional compounds onto temperature-sensitive polypropylene mesh (PP-M) surfaces. This approach is based on the recent advancements in cold atmospheric plasma (CAP) assisted deposition of SiO2 thin films and laser surface treatment (LST), enabling the selective heating and formation of functional glass-ceramic compounds under atmospheric conditions. A systematic study was conducted to identify optimal LST conditions that resulted in the effective formation of a bioactive glass-ceramic structure without significantly altering the chemical and mechanical properties of the underlying PP-M (less than 1% change compared to the original properties). The developed coating with optimized processing conditions demonstrated high biocompatibility and persistent antibacterial properties (>7 days) against both Gram-positive and Gram-negative bacteria. The developed process is expected to provide a new stepping stone towards depositing a wide range of functional bioceramic coatings onto different implant surfaces, thereby decreasing their risk of infection and associated complications.

Ultra-Short Pulse HiPIMS: A Strategy to Suppress Arcing during Reactive Deposition of SiO2 Thin Films with Enhanced Mechanical and Optical Properties

In this contribution, based on the detailed understanding of the processes’ characteristics during reactive high-power impulse magnetron sputtering (HiPIMS), we demonstrated the deposition of silicon oxide (SiO2) thin films with improved optical and mechanical performances. A strategy for stabilizing the arc-free HiPIMS of Si target in the presence of oxygen was investigated. Arcing was suppressed by suitable pulse configurations, ensuring good process stability without using any feedback control system. It was found that arcing can be significantly alleviated when ultra-short HiPIMS pulses are applied on the target. The optical and mechanical properties of SiO2 coatings deposited at various pulsing configurations were analyzed. The coatings prepared by ultra-short pulse HiPIMS exhibited better optical and mechanical performance compared to the coatings prepared by long pulse HiPIMS. The optimized SiO2 coatings on quartz substrates exhibited an average transmittance of 98.5% in the 190–1100-nm wavelength range, hardness of 9.27 GPa, hardness/Young’s modulus ratio of 0.138, and critical adhesion load of 14.8 N. The optical and mechanical properties are correlated with the film morphology, which is inherently related to energetic conditions and process stability during film growth.

Ozone based high-temperature atomic layer deposition of SiO2 thin films

In this paper, atomic layer deposition of SiO2 thin films was investigated with Si2Cl6 and O3/O2 (400 g m−3). O3/O2 is not preferred for high-temperature (>400 °C) processes due to its lower decomposition temperature, especially in a furnace-type chamber. However, with Si oxidation test using a cold-wall chamber, we have demonstrated the reactivity of O3/O2 up to 800 °C in comparison with O2 and H2O. The ALD of SiO2 films was examined at deposition temperatures from 500 °C to 700 °C. The growth rate at 600 °C was saturated to 0.03 nm/cycle with Si2Cl6 exposure over 1.2 × 105 L. O3/O2 also showed ALD-like saturation behaviors for exposures over 2.4 × 106 L. The ALD films deposited at 600 °C exhibited relatively smooth surface roughness (<0.18 nm) and low wet etch rate (1.6 nm min−1, 500:1 HF) that are comparable with PECVD SiO2 deposited at 250 °C and LPCVD SiO2 deposited at 450 °C.

Atomistic simulation of the glancing angle deposition of SiO2 thin films

The classical molecular dynamics simulation of the glancing angle deposition of silicon dioxide films with practically meaningful dimensions is performed. The formation of separated slanted columnar structures is investigated for different deposition angles and different energies of sputtered silicon atoms. It is shown that a decrease in the angle between the flux of deposited atoms and the normal to the substrate leads to the decrease of column thicknesses and distances between the columns. The high-energy deposition with small deposition angles results in the formation of dense films without separate columnar structures. The increase of substrate temperature leads to partial merging of nearby columns. The glancing angle deposition with low energies of sputtered silicon atoms results in the growth of disordered columns with different dimensions, shapes, and tilt angles. Annealing of high-energy glancing angle deposited films results in partial merging of slanted columns. The obtained simulation results are in a good agreement with existing experimental data.

The Characteristics of Silica Nano-powder and Thin Films Prepared from Rice Husk Ash

In this study we have conducted laboratory research on the characteristics of silicanano-powder andthin films prepared from rice husk ash by extractionmethod. Rice husk ash was obtained fromAcehBesar district, Aceh province, Indonesia. The extraction process was carried out using 1.5% KOH and 10% HCl solution. The deposition of SiO2 thin films was carried out by sol-gel method. SiO2 thin films were grown on a glass substrate by a dip coating technique. The precursor solution was prepared by dissolving 1 gram of silica nano-powder into 20 ml of ethanol and stirring for 60 minutes at 50 0C using a hot plate stirrer. The SiO2 thin films were then annealed at various temperature of 450 - 600 0C with a holding time of 60 minutes. XRD pattern showed that silica powder from rice husk ash has a nano-crystal structure. We found that there are other peaks besides SiO2. This indicated that silica nano-powder obtained by extraction method was still contains impurity elements. The characteristics of SiO2 thin films strongly depend on annealing temperature. The optical bandgap of SiO2 thin films varies from 3.63 - 3.68 eV.

Blocking Hot Electron Emission by SiO2 Coating Plasmonic Nanostructures

Noble metallic nanostructures provide a platform for high-sensitivity spectroscopic sensing with significantly enhanced electromagnetic fields due to surface plasmon polaritons. However, target molecules can be transformed into other molecules under irradiation with an excitation laser during the surface-enhanced measurement, which thus disturbs detection of unknown samples. In this paper, we perform Raman measurements of p-aminothiophenol on gold nanosurfaces with and without deposition of SiO2 thin films at the surface. The Raman signals are enhanced on both substrates, but the deposition of the glass thin film clearly prevents the chemical transformation. This indicates that hot electrons are effective for chemical transformation and that thin glass films are sufficient to prevent this while still benefiting from surface plasmons.

Glancing angle deposition of SiO2 thin films using a novel collimated magnetron sputtering technique

A novel deposition flux collimation technique has been explored in combination with glancing angle deposition geometry in radio frequency magnetron sputtering deposition technique with a motive to tailor the refractive index of silicon di-oxide thin film. In this technique, a collimating plate has been placed in parallel to the substrate at variable substrate to collimator distances (DSC=4mm, 6mm and 9mm) and the effect of DSC on various properties of the deposited film at different spatial locations on the substrate has been investigated. The use of such collimator was found to be highly effective in reducing the refractive index of the deposited film. A lowest refractive index of ~1.31 @ 550nm of SiO2 was achieved by using this novel collimation technique in combination with glancing angle deposition geometry which is not possible by glancing angle deposition geometry alone in the framework of non-directional deposition flux in magnetron sputtering technique. Variable angle spectroscopic ellipsometry (VASE) has been employed to accurately determine thickness and refractive index of the deposited films at various spatial locations of the sample. Ellipsometry data fitting model at different spatial locations has been verified by simulating the transmission spectrum based on the layer structure model obtained from ellipsometry modeling and then comparing it with that of the experimentally measured transmission spectra. For a given DSC an optimum location on the substrate surface was obtained to exhibit lowest refractive index. FTIR measurement showed no significant difference in bonding behavior of SiO among different representative spots of the deposited SiO2 samples. AFM measurement on various spatial locations indicates a possible strong correlation between variation of refractive index and the grain size which is again affected by the degree of collimation and ad atom kinetic energy at various spatial locations.

Full-atomistic nanoscale modeling of the ion beam sputtering deposition of SiO2 thin films

The previously developed high-performance parallel method of the atomistic simulation of the ion beam sputtering deposition process is applied to the SiO2 thin films. Structural properties of deposited films such as density, concentration of point defects, ring statistics, as well as effects arising from the interaction of high energy sputtered Si atoms with the growing film are discussed.

First-Principles Study of a Full Cycle of Atomic Layer Deposition of SiO2Thin Films with Di(sec-butylamino)silane and Ozone

The energy landscape of a full atomic layer deposition cycle to grow a layer of SiO2 on the hydroxylated SiO2(001) surface was systematically explored using density functional theory. A monoaminosilane-based compound, di(sec-butylamino)silane (DSBAS), was utilized as the silicon precursor with ozone acting as an oxidizing agent. The ALD cycle includes dissociative chemisorption of DSBAS, oxidation, and condensation for surface regeneration. Our results indicate that the dissociative chemisorption of DSBAS is kinetically facile. Upon oxidation by ozone, the layer grows with a SiO2 crystalline morphology. The entire ALD cycle was found to be thermodynamically and kinetically favorable. This is important for growing dense and conformal SiO2 thin films free of impurities and thus well-suited for low-temperature deposition of SiO2 thin films.

Deposition of SiO2 Thin Films on Polycarbonate by Atmospheric-Pressure Plasma

Low-temperature, atmospheric-pressure SiO2 thin film deposition was achieved using dielectric barrier discharge plasma with a high-voltage pulse. Experiments were conducted using diethoxydimethylsilane as the silicon source at different oxygen concentrations, gas flow rates, and deposition times. Hard, transparent thin-coated films were obtained at high oxygen concentrations because of the capture of carbon by oxygen during deposition. A deposition rate of 60 nm/min was achieved with the pulsed plasma at a duty ratio of 4%, gap length of 1 mm, and peak voltage of 13 kV without cooling or heating of the polycarbonate substrate. A usable SiO2 hard-coat film with a thickness of 1.6 µm and an indentation hardness of 1480 N/mm2 was obtained after a deposition time of 30 min in oxygen.

High Growth Rate SiO2 by Atomic Layer Deposition

A remarkably high growth rate of more than 1 Aå/cycle was obtained when using a new aminosilane precursor AHEAD{trade mark, serif} for atomic layer deposition of SiO2 thin films. The films were deposited at 150 - 300 {degree sign}C on 200 mm wafers. AHEAD{trade mark, serif} is a low vapour pressure liquid which was vaporised at 110 {degree sign}C. Ozone was used as the oxidizer.

Plasma-Enhanced Chemical Vapor Deposition of SiO2 Thin Films at Atmospheric Pressure by Using HMDS/Ar/O2

Plasma-Enhanced Chemical Vapor Deposition of SiO2 Thin Films at Atmospheric Pressure by Using HMDS/Ar/O2

Reactive sputtering deposition of SiO2 thin films

SiO2 layers were deposited in a UHV chamber by 1 keV Ar+ ion sputtering from a high purity silicon target, using different values of the oxygen partial pressure (5?10-6-2?10-4 mbar) and of the ion beam current on the target (1.67-6.85 mA). The argon partial pressure during operation of the ion gun was 1?10-3 mbar. The substrate temperature was held at 550?C and the films were deposited to a thickness of 12.5-150 nm, at a rate from 0.0018-0.035 nm s-1. Structural characterization of the deposited thin films was performed by Rutherford backscattering spectrometry (RBS analysis). Reactive sputtering was proved to be efficient for the deposition of silica at 550?C, an oxygen partial pressure of 2?10-4 mbar (ion beam current on the target of 5 mA) or, at a lower deposition rate, ion beam current of 1.67 mA and an oxygen partial pressure of 6?10-5 mbar. One aspect of these investigations was to study the consumption of oxygen from the gas cylinder, which was found to be lower for higher deposition rates.

SiO2 thin film deposition on the inner surface of a poly(tetra-fluoroethylene) narrow tube by atmospheric-pressure glow microplasma

SiO2 thin films were deposited on the inner surfaces of a commercial poly(tetrafluoroethylene) narrow tube with an inner diameter of 0.5 mm using tetraethoxysilane/O2 feedstock gases and He carrier gas by atmospheric-pressure microplasma-enhanced chemical vapor deposition. A glow microplasma was generated inside the tube by radio frequency (RF) capacitively coupled discharge. X-ray photoelectron spectroscopy spectra showed that the tube inner surface was covered by a SiO2 thin film. Transparent SiO2 thin films were obtained with a deposition rate of 230 nm/min at an RF power of 6 W and substrate temperature of 100 °C. The wettability of the SiO2-coated tube was about 3 times as large as that of an untreated sample tube.

Analysis of the Photochemical Reaction on the Surface for Room Temperature Deposition of SiO2 Thin Films by Photo-CVD using Vacuum Ultraviolet Light

We have analyzed the photochemical reaction for the deposition of SiO2 thin films at room temperature in photo-CVD using a vacuum ultraviolet (VUV) excimer lamp with reflection-absorption spectroscopy using a Fourier transform infrared spectrometer (RAS-FTIR). Tetraethoxyorthosilicate (TEOS) was used as a precursor and two types of excimer lamps were used as light sources. The reaction in VUV-CVD is divided into two stages: the reaction in the vapor phase, and the reaction on the surface of the substrate. In this work, we analyzed the latter stage. As a result of analyzing the spectra obtained, it was found that the main reaction for the formation of the SiO2 film was in the latter stage, in which the dissociation of Si–O bonds in Si–O–CH2 in the adsorbed fragments was preceded by the photo-dissociation of C2H5.

Pulsed Laser Deposition of SiO2 Thin Films with Dimethylpolysiloxane Targets

SiO2 thin films were deposited at room temperature by 193-nm ArF excimer laser ablation of dimethylpolysiloxane in oxygen atmosphere. Only the side chains (–CH3) of the target were photodissociated during ablation to deposit Si–O bonds on a substrate in a high laser fluence of about 10 J/cm2. Oxygen gas worked to oxidize the Si–O bonds ejected from the target to form SiO2 thin films at the gas pressure of 4.4×10-2 Torr, in addition to reducing the isolated carbon mixed into the films. The transmittance of the 400-nm-thick films was 95% at a 500 nm wavelength. The refractive index of the films was defined as 1.416 at a wavelength of 633 nm. The chemical composition was also confirmed to be SiO2 by X-ray photoelectron spectroscopy. No smooth and dense film was observed by a scanning electron microscope. Electrical resistivity of 107 Ωm was obtained.

RF discharge modelling in a N2O/SiH4 mixture for SiO2deposition and comparison with experiment

The present work concerns the experimental and theoreticalanalysis of the electrical behaviour and N2O/SiH4dissociation of a classical RF discharge used for SiO2 thin-filmdeposition. Electric and deposition rate measurements are undertaken at 0.5and 1 Torr gas pressures. The reactor modelling involves electrical,hydrodynamic and mass transfer models. The electrical model enables thecalculation of the electron impact dissociation rates required for the masstransfer model, while the gas velocities are determined by the hydrodynamicmodel. Only an electrical discharge model accounting for the negative-ionconversion reactions O-/SiH4 and NO-/SiH4allows good agreement between the measured and calculated power densitiesparticularly at 1 Torr. Furthermore, a simplified chemical scheme whichincludes 16 species (N2O, N2, O2, NO,NO2, N, O(3P), O(1D), SiH4, SiH3, SiH3O, H2SiO, H, H2, OH and H2O) is used in the mass transfer model. The corresponding results(deposition rates) are quite consistent with the measurements.

Deposition of SiO2 Thin Films by Combined Low-Energy Ion-Beam and Molecular-Beam Epitaxial Method

A combined ion-beam and molecular-beam epitaxial (CIBMBE) method was applied for the deposition of SiO2 thin films using a mass-separated low-energy (50 eV) O+ ion-beam and a Si molecular-beam. From X-ray photoelectron spectra, it was confirmed that stoichiometric SiO2 thin films were successfully formed, and it was suggested that the chemical state of the Si atoms in the SiO2 layers is identical (Si4+) to that in the films formed by the thermal oxidation of Si. It was suggested that the CIBMBE is a versatile technique for the deposition of SiO2 thin films whose quality is comparable to that of the films formed by the thermal oxidation method.

12-Tungstosilicic Acid (12-TSA) as a Tungsten Precursor in Alcoholic Solution for Deposition of xWO3(1 − x)SiO2 Thin Films (x ≤ 0.7) Exhibiting Electrochromic Coloration Ability

The preparation of stable alcoholic solution of tungstosilicic acid and silicon alkoxide, which can be used for xWO3 (1 − x)SiO2 thin film deposition by dipping, is described. After thermal treatment at temperatures 440 to 500°C in nitrogen films with x higher than 0.6 exhibit electrochromic coloration ability. After coloring the film by H+ imtercalation (by contact with an indium wire trough a drop of aqueous solution of H2SO4) the luminous transmittance (illuminant D65, wavelength range from 380 to 780 nm, summation at 10 nm intervals) of glass coated with 90 nm thick xWO3(1 − x)SiO2 thin film decreases from 71.7 to 28.6% and the IR reflection increases to over 30%. At the same time the surface resistance decreases from a few MΩ/□ to about 400Ω/□. The thermal decomposition of tungstosilic acid embedded in alkoxy-hydroxy-oxy-silicon matrix is investigated with DTA, TGA, XRD and FTIR spectroscopy.

Low temperature deposition of SiO2 thin films on plastics as a hard coating using TEOS/Oz-plasma 3 Hiroaki Tamamaki, Masaya Nomura, Keiichiro Sano (Suzuki Motor Corp.), Yoichiro Nakanishi, Yoshinori Hatanaka (Shizuoka University Research Institute of Electronics)

Low temperature deposition of SiO2 thin films on plastics as a hard coating using TEOS/Oz-plasma 3 Hiroaki Tamamaki, Masaya Nomura, Keiichiro Sano (Suzuki Motor Corp.), Yoichiro Nakanishi, Yoshinori Hatanaka (Shizuoka University Research Institute of Electronics)