Radio-frequency Plasma Chemical Vapor Deposition Research Articles

Improvement of corrosion resistance and mechanical properties of chrome plating by diamond-like carbon coating with different silicon-based interlayers

In this study, the silicon-based interlayers for hydrogenated amorphous carbon (a-C:H) coating on a chromium-plated substrate are presented. The a-Si, a-Si:N, a-Si:H and a-SixCy:H interlayers with a thickness of about 306 nm were deposited by direct current magnetron sputtering technique. The a-C:H films with a thickness of about 317 nm was prepared as a top layer by radio frequency-plasma chemical vapor deposition. The a-C:H films with silicon-based interlayers were characterized by x-ray photoelectron spectroscopy, Raman spectroscopy, field emission-secondary electron microscopy, nanoindentation, micro-scratching, and electrochemical corrosion measurements in terms of their structure, morphology, mechanical and adhesive properties, and corrosion resistance. The a-C:H films with an a-Si:H interlayer exhibit the lowest corrosion current density, which is about 36 times lower than that of the uncoated chromium-plated substrate. In addition, the hardness increases from 8.48 GPa for the uncoated substrate to 20.98 GPa for the a-C:H/a-Si:H sample. The mixing with hydrogen gas could reduce the residual oxygen during the deposition process, which could reduce the Si–O bonding and improve the adhesion strength between the a-C:H film and the a-Si:H interlayer and the a-Si:H interlayer and the substrate. Therefore, it can be concluded that the protective a-C:H coating with an a-Si:H interlayer has excellent potential to significantly improve the durability and extend the service life of materials used in abrasive and corrosive environments.

Investigation on formation of thin Si-B-N films on stainless steel by plasma chemical vapor deposition

Amorphous Si-B-N alloy films on SS304 stainless steel substrates prepared by using radio frequency plasma chemical vapor deposition (RF-PCVD) from the mixture gases of N2, Ar, B2H6 and SiH4. It is found that both hardness and wear resistance of the samples with film coating were improved significantly. There are N, Si, and B existing in deposited films through the XPS and the FT-IR measurement. SEM images of the film surface presents the morphology of hilly clusters composed of small particles. Energy dispersive spectrometry (EDS) and glow discharge optical emission spectrometry (GD-OES) were used to investigate the early nucleation and growth. At the early growth stage of 5 min, the continuous film formed is composed of small particles with a diameter of tens of nanometers on the substrate, suggesting that the precursor species easily nucleate on the stainless steel surface. The examination of cross-section for film coating indicates that an interface layer with diffusion forms during the deposition process, which is attributed to highly reactive species containing silicon, boron and nitrogen generated in discharging plasma. Those have high enough energy to induce diffusion effect in interface layer.

Tribological behavior of diamond-like carbon produced by rf-PCVD based on energetic evaluation

Two types of diamond-like carbon (DLC) were evaluated for their tribological behavior in terms of the tribometer input energy. The DLC samples were prepared from methane (denoted DLC[CH4]) or benzene (denoted DLC[C6H6]) as a gas source on tungsten-carbide (WC) substrates by radio-frequency plasma chemical vapor deposition (rf-PCVD). The hydrogen contents of the DLCs were measured by Elastic Recoil Detection Analysis (ERDA). The DLC structures were investigated by Raman spectrometry and X-ray photoelectron spectroscopy (XPS). The basic mechanical properties, such as the hardness and the Young's modulus, were obtained by a nano-indenter. The DLC films against alumina were tribo-tested by a ball-on-disk. The input energy was calculated using the applied load, the friction coefficient, and the sliding distance in each tribo-test. The wear behavior of the DLC[CH4] sample was better than that of the DLC[C6H6], even though the hardness of DLC[CH4] was lower than that of DLC[C6H6]. The wear loss of DLC[CH4] and DLC[C6H6] was evaluated by the input energy, and the wear resistance difference of the DLCs was characterized in terms of the input energy.

Microstructural evolution by in-situ TEM observations of oxides

In-situ observations using high-temperature transmission electron microscopy (TEM) is a promising technique for obtaining new findings and developing phenomenological theory for ceramic materials at high temperatures. By observing the changes in hydrothermal BaTiO3 due to heating, we clarify the vanishing mechanism of internal pores and the mechanism of BaCO3 phase generation/vanishing at high temperatures. Through observations of the grain growth of BaTiO3 prepared by radio-frequency plasma chemical vapor deposition, we calculate the grain-boundary diffusion coefficient, which is an important parameter controlling the sinterability of ceramics. Observations of the shrinkage and disappearance of Ba5Nb4O15, as well as simulations, indicate that high energy and low diffusivity at the grain boundary make grains vanish while maintaining a truncated spherical shape. Finally, observations of the structural changes in layered perovskite BaLn2Mn2O7 (Ln = Gd, Pr, Eu) reveal a first-order phase transition that has not been previously reported.

The wear properties and adhesion strength of the diamond-like carbon film coated on SUS, Ti and Ni–Ti with plasma pre-treatment

Diamond-like carbon (DLC) films were deposited on stainless steel (SUS), titanium (Ti) and nickel titanium (Ni-Ti) substrates using a radiofrequency plasma chemical vapour deposition method. Prior to DLC coating, the substrates were exposed to O2 and N2 plasma to enhance the adhesion strength of the DLC film to the substrate. After the plasma pre-treatment, the chemical composition and the wettability of the substrate surface was investigated by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement, respectively. A pull-out test and a ball-on-disc test were carried out to evaluate the adhesion strength and the wear properties of the DLC-coated substrates. The XPS results showed that the N2 and O2 plasma pre-treatment produced nitride and oxide on the substrate surfaces, such as TiO2, TiO, Fe2O3, CrN and TiNO. In the pull-out test, the adhesion strengths of the DLC film to the SUS, Ti and Ni-Ti substrates were improved with the plasma pre-treatment. In the ball-on-disc test, the DLC coated SUS, Ti and Ni-Ti substrates without the plasma pre-treatment showed severe film failure following the test. The DLC coated SUS and Ni-Ti substrates with the N2 plasma pre-treatment showed good wear resistance, compared with that with the O2 plasma pre-treatment.

The effect of nitrogen and oxygen plasma on the wear properties and adhesion strength of the diamond-like carbon film coated on PTFE

Diamond-like carbon (DLC) films were deposited on polytetrafluoroethylene (PTFE) using a radiofrequency plasma chemical vapour deposition method. Prior to DLC coating, the PTFE substrates were modified with O 2 and N 2 plasma to enhance the adhesion strength of the DLC film to the substrate. The effect of the plasma pre-treatment on the chemical composition and the surface energy of the plasma pre-treated PTFE surface was investigated by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurement, respectively. A pull-out test and a ball-on-disc test were carried out to evaluate the adhesion strength and the wear properties of the DLC-coated PTFE. In the N 2 plasma pre-treatment, the XPS result indicated that defluorination and the nitrogen grafting occurred on the plasma pre-treated PTFE surface, and the water contact angle decreased with increasing the plasma pre-treatment time. In the O 2 plasma pre-treatment, no grafting of the oxygen occurred, and the water contact angle slightly increased with the treatment time. In the pull-out test, the adhesion strength of the DLC film to the PTFE substrate was improved with the plasma pre-treatment to the PTFE substrate, and N 2 plasma pre-treatment was more effective than the O 2 plasma pre-treatment. In the ball-on-disc test, the DLC film with the N 2 plasma pre-treatment showed good wear resistance, compared with that with O 2 plasma pre-treatment.

Application of Time-of-Flight Secondary Ion Mass Spectrometry to study diamond-like carbon films

Chemical composition and some differences between surface and bulk structure of diamond-like carbon (DLC) thin films studied with Time-of-Flight Secondary Ion Mass Spectrometry (ToF SIMS) are the subject of this paper. The DLC films were deposited using radio-frequency plasma-chemical vapor deposition (RF PCVD) method by the decomposition of CH 4 gas in high-frequency plasma. The negative self-bias voltage defining the power used for deposition was in the range of − 100 V to − 400 V. The results obtained show that the DLC films primarily contain carbon and hydrogen. The collected depth profiles also show that all samples contain considerable amount of Fe, Ni, Cr and some other elements introduced during the deposition process. These elements are mainly placed at the interface region of the substrate and deposited in the DLC film. The mass spectra obtained show that the amount of hydrogen in the surface layer is much greater than in the sample bulk which is consistent with widely accepted models of deposition of hydrogenated DLC films. The structure of the studied DLC samples was characterized by the analysis of negative carbon cluster ions in the mass spectra obtained. Some significant differences in the surface and bulk energy of fragmentation of carbon clusters are registered. The results suggest that the fragmentation pattern is independent of the self-bias voltage used during film deposition.

Effect of negative pulsed high-voltage-bias on diamond-like carbon thin film preparation using capacitively coupled radio-frequency plasma chemical vapor deposition

Mechanical properties of diamond-like carbon films by an effective addition of negative pulsed high-voltage-bias have been investigated in capacitively coupled CH 4/Ar radio-frequency plasma. The results revealed that hardness and elastic modulus of the deposited film, estimated from nano-indentation load–displacement curve for about 1 μm-thick films, increase with the increase of the absolute value of high-voltage V NPHV for V NPHV < 5 kV and then saturate. Elastic recovery R got the highest value (> 90%) at V NPHV = 5 kV.

Phase transformation of BaTiO 3 nanoparticles synthesized by RF-plasma CVD

The present paper reports an investigation on the size-dependent cubic-tetragonal phase transformation of barium titanate (BaTiO 3) using BaTiO 3 nanoparticles prepared by radio-frequency plasma chemical vapor deposition (RF-plasma CVD) as starting materials. The particle sizes of BaTiO 3 were controlled by heat treatment of as-prepared BaTiO 3 nanoparticles at various temperatures. The BaTiO 3 nanoparticles under 30 nm (= d SEM: D 50 of particle size distribution obtained from SEM image) were assigned to a perfect cubic structure using Raman spectroscopy and Rietveld analysis. In the range from 30 to 70 nm ( d SEM), the stable phase at room temperature gradually transformed to a tetragonal structure, which suggests that the crystal structure in this region is pseudo-cubic. Considering the reliability factor of the Rietveld analysis, the phase transformation from cubic to tetragonal was confirmed to have occurred above 70 nm ( d SEM). The products of 100 nm ( d SEM) showed tetragonality (lattice constant ratio of the c-axis to the a-axis in perovskite unit cell) of 1.008 by Rietveld analysis and an endothermic peak in the DSC profile due to the tetragonal-cubic transformation at the Curie temperature. This suggests that a clear tetragonal structure can be observed above 100 nm.

Effect of mechanical stress on the absorption band tail of cubic boron nitride thin films synthesized by inductively coupled radio-frequency plasma chemical vapour deposition

Thin films of cubic boron nitride were deposited on silica and Si substrates by inductively coupled radio-frequency plasma chemical vapour deposition (IPCVD) technique using a B2H6 + N2 + Ar gas mixture. Cubic phase formation was confirmed by glancing-angle X-ray diffraction studies, which showed reflections up to (311). Fourier-transform infrared (FTIR) spectra also indicated the predominantly cubic nature of the deposited films. The optical properties of the films were studied in the wavelength range 200–1000 nm. Both direct and indirect transitions were found to be present. Mechanical stress in the grain-boundary region of the films seems to contribute significantly to the optical absorption below the band gap. The intercrystalline barrier height (E b) and the trap state density (Q t ) were obtained from an analysis of the effects of grain boundaries on the optical properties of the samples.

Study of Carbon Films on Silicon Substrates

Carbon based films on silicon substrates have been studied by high resolution FE SEM equipped by an EDS analyzer. The first type are carbon nanotube (CNT) [1] films prepared on Si/SiO2 substrates with Ni or Fe layers by radiofrequency plasma chemical vapor deposition. Dependence of nanotube films properties on Ni and Fe thickness and deposition conditions have been studied. The second type of films discussed are microcrystalline and nanocrystalline diamond films grown on pre-treated Si substrates by microwave plasma chemical vapor deposition (MPCVD). The pre-treatment was varied and its effect on diamond films was studied.

Size driven phase transition of barium titanate nanoparticles prepared by plasma chemical vapor deposition

Size driven phase transition of barium titanate nanoparticles prepared by plasma chemical vapor deposition

Growth of amorphous hydrogenated carbon nitride films in radio-frequency plasma

Amorphous hydrogenated carbon nitride films are deposited both on the cathode and anode in N2–CH4 atmosphere by radiofrequency plasma chemical vapor deposition. The species of the plasma are detected by optical emission spectroscopy and ionization-threshold mass spectroscopy. The effects of varying the N2 partial pressure on plasma states and film properties have been investigated. The results of plasma diagnosis indicate that reactive nitrogen radicals are more easily generated than methane-derived radicals and they increase as the N2 partial pressure in plasma. The films grown on the cathode and anode definitely show different properties. It seems that CN and CNH species in plasma do not contribute to film growth directly. The efficient bombardment of nitrogen ions on growing surface leads to the formation of the film which has lower hydrogen content and more CN bond constructions.

Formation of Carbon Nitride Films by the Radio-Frequency Plasma Chemical Vapor Deposition Method

Carbon nitride films are deposited both on the cathode and anode in a CH4-N2 atmosphere by radio frequency plasma chemical vapor deposition. An increase in rf power and a decrease in gas pressure lead to an increase in the self-bias voltage, which increases ion energy and ion bombardment. The films grown on the cathode and anode definitely show different properties with or without ion bombardment under the same deposition conditions. The films produced with efficient ion bombardment have lower hydrogen content, higher electrical conductivity and greater hardness. The conductivity is affected by characteristics of the films such as the bonding state of the carbon, nitrogen and hydrogen and by the number of defects in the films. It is likely that conductivity is not dominated by band conduction but by hopping conduction. It is clear that efficient ion bombardment and ion energy during film growth are important factors in producing electrically conductive and hard carbon nitride films.

Deposition and characterization of dense and stable amorphous hydrogenated boron films at low substrate temperatures

Amorphous hydrogenated boron (a-B:H) thin films were prepared by radio-frequency plasma chemical vapor deposition of B 2H 6 diluted in hydrogen. The influence of deposition parameters on chemical composition and structural properties were determined by ion beam analysis, Fourier transform infrared (FTIR), X-ray photoelectron (XPS) and thermal desorption (TDS) spectroscopy. FTIR and XPS analysis show differences in film stability depending on ion energy. Films deposited at low substrate temperatures and low ion energies undergo chemical changes when exposed to atmosphere. XPS and FTIR revealed that these chemical changes are accompanied by an incorporation of carbon and oxygen into the bulk of the film. Stable films were prepared at substrate temperatures as low as 330 K if the ion energy is sufficiently high (self-bias voltages >150 V). No chemical changes of these films were observed after 15 months of exposure to ambient atmosphere. Chemical stability correlates with boron density which lies between 1.6–1.85 g/cm 3 for stable films.

Electrical conductivity of metal/diamond‐like carbon/si system

Interest in diamond-like carbon (DLC) thin films has increased considerably in the last few years. It is suggested that DLC films may be used for electronic devices, especially working at high temperatures. The subject of this contribution is the electrical conduction of a metal/DLC/ Si system. The investigated DLC films were prepared by two methods: radio-frequency plasma chemical vapour deposition (RF-PCVD) and pulsed cathodic-arc discharge (PCAD) on silicon substrates. The metal/DLC/silicon heterojunctions show rectifying characteristics. The rectifying character of the current-voltage behaviour may be caused by a thin Interfacial SiO2 sublayer existing between the DLC film and silicon.

Silica coating of aluminium nitride particles by radio-frequency plasma chemical vapour deposition

Silica coating of aluminium nitride particles by radio-frequency plasma chemical vapour deposition

Silica coating of aluminium nitride particles by radio-frequency plasma chemical vapour deposition

Silica coating of aluminium nitride particles by radio-frequency plasma chemical vapour deposition

高周波プラズマＣＶＤ法によって形成された酸化ケイ素膜のガス透過性

Silicon oxide films were prepared on polyethylene terephthalate film by radio-frequency plasma chemical vapor deposition using hexamethyl disiloxane (HMDSO) and oxygen gas and intentionally not heating the substrate.We studied the influence of the surface conditions of the substrate on gas permeability of films. We also studied the compositional and structual properties of films through infrared absorption, refractive indexing, and X-ray photo-electron spectroscopy (XPS).Silicon oxide films prepared by using HMDSO and oxygen gas plasma featured high gas-barrier properties, which were affected by the surface conditions of the substrate. We confirmed that it was necessary to bombard the substrate using HMDSO plasma as a pretreatment in order to obtain a silicon oxide film with higher gasbarrier properties.

Determination of electrode/substrate surface temperatures through the solid–liquid transition of metals/eutectics in capacitively coupled radio frequency-plasma chemical vapor deposition reactors

In a capacitively coupled radio frequency-plasma chemical vapor deposition reactor, we took pure metals, In, Sn, Bi, and Pb with the melting points ranging from 157 to 327 °C, and the eutectic Al (45 wt. %)/Ge alloy with the eutectic point of 423 °C as the fixed point materials to determine surface temperatures of the electrode and a piece of stainless steel (SLS) plate placed on it. The surface temperatures thus obtained were compared with temperatures detected with a thermocouple mounted within the electrode. An analysis of the obtained results based on a simplified heat transfer model revealed the thermal contact resistance at the specimen-SLS plate interface to be as small as about one sixth that at an interface between two pieces of SLS plate. Criteria for the choice of eutectics as the thermometric fixed-point materials are discussed and some possible candidates usable for this purpose are listed.