Pressure Plasma Chemical Vapor Deposition Research Articles

Synthesis of Diamond-Like Carbon Films on Planar and Non-Planar Geometries by the Atmospheric Pressure Plasma Chemical Vapor Deposition Method

Diamond-like carbon (DLC) films were synthesized by the dielectric barrier discharge-based plasma deposition at atmospheric pressure and their hardness and gas barrier properties were measured. A decrease in size of grains and heating substrate temperature improved nano-hardness up to 3.3 GPa. The gas barrier properties of DLC-coated poly(ethylene terephthalate) (PET) sheets were obtained by 3–5 times of non-coated PET with approximately 0.5 µm in film thickness. The high-gas-barrier DLC films deposited on PET sheets are expected to wrap elevated bridge of the super express and prevent them from neutralization of concrete. We also deposited DLC films inside PET bottles by the microwave surface-wave plasma chemical vapor deposition (CVD) method at near-atmospheric pressure. Under atmospheric pressure, the films were coated uniformly inside the PET bottles, but did not show high gas barrier properties. In this paper, we summarize recent progress of DLC films synthesized at atmospheric pressure with the aimed of food packaging and concrete pillar.

Synthesis of hydrogenated amorphous carbon films with a line type atmospheric-pressure plasma CVD apparatus

In this study, hydrogenated amorphous carbon (a-C:H) films were synthesized on polyethylene terephthalate (PET) substrates with a line type atmospheric-pressure plasma chemical vapor deposition (CVD) apparatus. Acetylene and nitrogen mixture gas was used for process gas and a-C:H films having two different thickness were synthesized with varying the C2H2 mixing rates. We investigated the effect of chemical bonding structure on the ultraviolet ray shielding property of the films. The deposition rate increased as a function of the C2H2 mixing rates. Increasing the C2H2 mixing rate from 2.5 to 10% caused an increase in the deposition rates from 13 to 22nm/s. The deposition rate under atmospheric pressure was faster than that of low-pressure plasma CVD (~5–16nm/s). Ultraviolet transmittance of 2μm thick a-C:H film synthesized at the C2H2 mixing rate of 10% on 100μm thick PET substrates ranged from 0 to 3% as the UV wavelength ranged from 310 to 400nm, while that of uncoated PET substrates ranged from 0 to 80%. From the result of X-ray photoelectron spectroscopy (XPS) analysis, the component of sp2-hybridized C, such as CC and CO bonds increased as the C2H2 mixing rate and thickness of a-C:H films increased. A decrease of sp3-hybridized C, such as CC and CO bonds and an increase of sp2-hybridized C bonds lead to an improvement of ultraviolet ray shielding property.

An atomically controlled Si film formation process at low temperatures usingatmospheric-pressure VHF plasma

To grow epitaxial Si films with atomic- and electronic-level perfection,a high-temperature chemical vapor deposition (CVD) process (>1000 °C) has been generally employed. To reduce the growth temperature below600 °C but keeping a high deposition rate, other energy sources than thermal heating are required.Atmospheric pressure plasma CVD (AP-PCVD) is considered to be suitable for fabricatinghigh-quality films at high deposition rates due both to the high radical densityand to the low ion bombardment against the film surface, because the collisionfrequency among ions and neutral atoms is high. The present study focuses on thelow-temperature growth of epitaxial Si, and experimentally demonstrates thatAP-PCVD is capable of growing epitaxial Si films with high perfection applicable forsemiconductor devices. It is found that the pre-growth cleaning of the Si surface byH2 AP plasma is effective to grow high-purity Si films, and that the exposure of a film-growingsurface to AP plasma during growth is important to form particle-free and defect-free Sifilms. From the experimental results and the first-principles molecular dynamicssimulations of surface atomic reactions, it can be mentioned that both H atoms in the APplasma and high-density He atoms having thermal kinetic energy contribute to thereduction of growth temperature by supplying considerable energy to the surface.

An Approach to Create Silver Containing Antibacterial Coatings by Use of Atmospheric Pressure Plasma Chemical Vapour Deposition (APCVD) and Combustion Chemical Vapour Deposition (CCVD) in an Economic Way

AbstractThe aim of this study was to test the possibilities of using APCVD and CCVD to create effective antibacterial coatings and to determine their antibacterial activity. SiOx‐layers were created by use of a hexamethyldisiloxane (HMDSO) precursor in combination with silver nitrate solution and silver nanoparticles as additives. A strong antibacterial effect of the APCVD and CCVD coated samples on an Escherichia coli (E. coli) strain could be shown. Layers obtained by CCVD showed a longer‐lasting antibacterial activity. The results were verified using a commercially available microbial cell viability assay basing on the measurement of bacterial adenosine triphosphate (ATP) or by counting of colony forming units (CFU) on agar plates. magnified image

Plasma enhanced CVD of SiO xC yH z thin film on different textile fabrics: Influence of exposure time on the abrasion resistance and mechanical properties

In order to improve textile fabric abrasion resistance, in this work a SiO x C y H z thin film was realized by low pressure plasma chemical vapour deposition (PCVD) at room temperature, using hexamethyldisiloxane (HMDSO) as precursor compound. To test changes in the performance properties of the surface finished samples as a function of the type of the substrate, the deposition was carried out on different textile fabrics. The polymerization processes were followed by weight measurements of textile fabrics. It was found that, after PCVD, a significantly lower fabric weight loss was observed on treated samples after rubbing than on the untreated samples. The morphology, elemental composition and type of chemical bonding present in the film applied on textile fabrics were also investigated using electron scanning microscopy (SEM), energy dispersive X-ray (EDX) and infrared spectroscopy techniques (FT-IR (ATR)). The results showed a substantial enhancement of wear resistance for the surfaces modified with the presented process, while tensile and tearing strength were adversely affected.

In Situ Doped Si Selective Epitaxial Growth at Low Temperatures by Atmospheric Pressure Plasma CVD

We have investigated characteristics of in situ B-doped and selective Si epitaxial growth by atmospheric-pressure plasma chemical vapor deposition (AP-PCVD) at VHF frequency. Using B2H6 as a doping gas, defect-free in situ B-doped epitaxial Si films were grown by AP-PCVD at 570ºC. A high carrier concentration up to 1020 cm-3 was achieved at a high growth rate of 0.20 μm/min. The hole mobility of highly B doped Si films is the same as that of bulk Si single crystals, demonstrating that the electrical quality of AP-PCVD Si film is high enough for semiconductor device applications. Si selective epitaxial growth by AP-PCVD has also been studied using atomic hydrogen as etchant species. Highly selective epitaxial growth of Si with good film quality has been observed at 470ºC by increasing H2 gas concentration in the plasma.

Deposition of low dielectric constant SiOC films by using an atmospheric pressure microplasma jet

Low dielectric constant (low-k) SiOC films have been prepared by using an atmospheric pressure microplasma jet (APPJ) from mixtures of tetraethoxysilane (TEOS) and argon (Ar). By decreasing the Ar flow rate from 10 to 2 slm, the dielectric constant of films can be reduced almost linearly to values of about 2.1. Moreover, the film deposition rate increases dramatically to the maximum value of 23 nm s−1, which is much higher than that in a low pressure plasma chemical vapour deposition (LPCVD) system. The leakage current density of films increases with increasing electric field, but has a low value of 1 × 10−8 A cm−2 at 1 × 106 V cm−1, which is similar to the value of samples deposited by LPCVD. It has promising applications as interconnect dielectrics for future generations of advanced integrated circuits (ICs), in addition, demonstrating the feasibility of using APPJ as a substitute for costly and cumbersome low pressure equipment in the production process.

High-quality epitaxial Si growth at low temperatures by atmospheric pressure plasma CVD

We have studied the epitaxial Si growth on 4-inch-(001) Si wafers by atmospheric pressure plasma chemical vapor deposition (AP-PCVD) using a porous-carbon electrode. Defect-free growth of epitaxial Si is confirmed in the temperature range 470–570 °C by transmission electron microscopy. High minority carrier generation lifetime (2.0 ms) is observed in the Si film grown at 570 °C with a rate of 0.35 μm/min. In situ H 2 AP-plasma cleaning of the substrate surface is effective for eliminating O and C concentration peaks at the film/substrate interface. Effects of plasma heating and ion bombardment of the growing-film surface have been discussed.

Deposition of transparent conductive indium oxide by atmospheric-pressure plasma jet

Indium (III) beta-diketonate complexes were employed as the solid precursor sources in the atmospheric-pressure plasma chemical vapor deposition of indium oxide films using He carrier gas, O 2 reactant gas and growth temperatures from 25 to 250 °C. Ellipsometry and X-ray reflectivity showed that the films varied in thicknesses from 40 to 70 nm over the 30 cm 2 deposition growth area for a 12 min duty cycle. The as-deposited films exhibit transmittance in excess of 90% over the visible spectrum while maintaining resistivity on the order of 10 − 2 Ω cm. Improved electrical properties (i.e., ρ < 10 − 3 Ω cm) were observed after thermal treatment ( T ~ 200 °C) in a controlled gas ambient tube furnace.

First‐principles analysis of He and H atom incidence onto hydrogen‐terminated Si(001) 2 × 1 surface

AbstractIn order to analyze the fundamental processes in atmospheric pressure plasma chemical vapor deposition, which has an ability to form silicon epitaxial films under low‐substrate‐temperature conditions, first‐principles microcanonical molecular‐dynamics simulations of collision process between plasma gas atoms (H and He) and Si(001) 2 × 1 hydrogen‐terminated surface are performed. In contrast to the He collision which results in simple bound, the formation of H2 molecule with exothermally generated kinetic energy of 1.1 eV, and the absorption of H atom, are observed in the case of H collision. The generated H2 molecule occasionally hits the adjacent H‐termination atom transferring a considerable amount of the kinetic energy of about 0.25 eV to the surface. It is suggested that this transferred energy might enhance the migration of reaction precursors, which is important for the improvement of the crystal quality of epitaxial films. In the comparison of induced energies to the surface, the collision process of H atom is more important than that of He. Copyright © 2008 John Wiley &amp; Sons, Ltd.

In situ B‐doped Si epitaxial growth at low temperatures by atmospheric‐pressure plasma CVD

AbstractIn situ B‐doped Si epitaxial growth by atmospheric‐pressure plasma chemical vapor deposition (AP‐PCVD) using porous carbon electrode was investigated. Heavy B doping for a carrier concentration of 8 × 1019 cm−3 was achieved using B2H6 as a doping gas, with a high average growth rate of 0.20 µm min−1 at 570 °C. The relation between the hole mobility and carrier concentration in heavily B‐doped Si films can be well fitted with that reported for bulk Si single crystals up to the carrier concentration of 5 × 1019 cm−3. This result demonstrates that the electrical quality of heavily doped Si epitaxial films grown by AP‐PCVD is sufficiently high for semiconductor device applications. The activation ratio of B atoms as acceptors in the heavily doped films is nearly 100% for a carrier concentration range reaching approximately 2 × 1019 cm−3. Cross‐sectional transmission electron microscopy examination of heavily B‐doped epitaxial Si with a carrier concentration of 2 × 1019 cm−3 revealed both a defect‐free film and film/substrate interface. In the present experiment, the required B2H6/SiH4 ratio is much higher than the resultant B composition in the Si films, due to thermal decomposition of B2H6 molecules in the porous carbon electrode. To increase the efficiency of B2H6 gas usage, cooling of the porous carbon electrode during the AP‐PCVD process may be effective. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Photoluminescence Study of Defect-Free Epitaxial Silicon Films Grown at Low Temperatures by Atmospheric Pressure Plasma Chemical Vapor Deposition

High-quality epitaxial Si films have been grown at low temperatures (500–600 °C) by atmospheric pressure plasma chemical vapor deposition (AP-PCVD) with a high growth rate (0.31 µm/min at 600 °C averaged over the 4-in. wafer). In contrast to the previous reports on other low-temperature CVD Si, the films in the present study are defect-free as observed by transmission electron microscopy and selective etching, and show no oxygen and carbon pileups at the film/substrate interface. To characterize defect-free epitaxial films with high sensitivity, we employed a photoluminescence (PL) method. When the epitaxial layer has better quality than the substrate, PL spectrum at 4.2 K mainly reveals the property of the substrate. On the other hand, room temperature PL measurements clearly show that the PL intensities of the surface-passivated epitaxial Si samples are much higher than that of Czochralski (CZ)-Si, which indicates a longer minority carrier recombination lifetime in the epitaxial Si layer than the bulk lifetime in CZ-Si.

Low-temperature and high-rate growth of epitaxial silicon by atmospheric-pressure plasma chemical vapor deposition

Low-temperature and high-rate growth of epitaxial silicon by atmospheric-pressure plasma chemical vapor deposition

Ge Nuclei for Fabrication of Poly-Si Thin Films on Glass Substrates

As nucleation sites for solid-phase crystallization (SPC) of a- Si thin films, crystalline Ge islands controlled in size and density were fabricated on glass and SiO2 substrates. Self- assembled crystalline Ge islands were formed by the SPC of a-Ge thin films on glass substrates. By annealing the samples under a reduced pressure of oxygen above 350{degree sign}C, Ge islands were etched to form volatile GeO species (oxygen etching). Single- crystalline Ge islands with good crystallinity and controlled in size and density were fabricated on glass substrates by a simple process combining SPC and oxygen etching. The crystallization times by SPC annealing of a-Si thin films deposited on SiO2 substrates with and without Ge nuclei were studied by Raman spectroscopy and transmission electron microscopy. Marked reductions of the crystallization time and temperature were observed in the SPC of a-Si:H thin films deposited by atmospheric pressure plasma CVD on SiO2 substrates with crystalline Ge islands.

Structural Characterization of Polycrystalline 3C–SiC Films Prepared at High Rates by Atmospheric Pressure Plasma Chemical Vapor Deposition Using Monomethylsilane

Polycrystalline cubic silicon carbide (3C–SiC) films were deposited at a relatively low temperature of 1070 K on Si(001) substrates by atmospheric pressure plasma chemical vapor deposition. Monomethylsilane (CH3SiH3) was used as the single source. CH4 and SiH4 dual sources were also used to compare deposition characteristics. Under the present deposition conditions, very high deposition rates of more than 3 nm/s were obtained. The structure of the SiC films was evaluated by reflection high-energy electron diffraction, Fourier transform infrared absorption spectroscopy and cross-sectional transmission electron microscopy. In addition, optical emission spectroscopy was employed to study the chemical reactions in the CH4/SiH4 and CH3SiH3 plasmas. The results showed that increasing H2 concentration is essential in forming a high quality 3C–SiC film by enhancing the hydrogen elimination reaction at the film-growing surface. From the optical emission spectra, it was found that atomic hydrogen generated by adding H2 in the plasma increase the amount of principal precursors for the film growth. The utilization of CH3SiH3 also led to a higher concentration of principal precursors in the plasma, enhancing the incorporation of Si–C bonds into the film. As a consequence of simultaneously using a high H2 concentration and the CH3SiH3 single source, the columnar growth of 3C–SiC crystallites was achieved.

Low-Temperature Growth of Epitaxial Si Films by Atmospheric Pressure Plasma Chemical Vapor Deposition Using Porous Carbon Electrode

The low-temperature growth of epitaxial Si films by atmospheric pressure plasma chemical vapor deposition (AP-PCVD) was investigated. A 150 MHz very high frequency (VHF) power supply was used to generate an atmospheric pressure plasma of gas mixtures containing He, H2, and SiH4. Two types of electrode (i.e., cylindrical rotary and porous carbon electrodes) were used in plasma generation. When a cylindrical rotary electrode was used, polycrystalline Si growth was inevitable at the film edge on the upstream side. This is due to the variation in deposition rate along the gas flow direction, which is extremely high at the plasma/atmosphere interface on the upstream side. To solve this problem, we developed a novel porous carbon electrode where process gas molecules are directly supplied into the plasma region through a porous carbon plate a distance (0.8 mm) away from the substrate surface. Using such a porous carbon electrode, we successfully grew a defect-free epitaxial Si film on the entire surface of a 4 in. Si wafer at 600 °C. The average growth rate was 0.25–0.3 µm/min, which is as high as that obtained by thermal CVD at 900 °C. The epitaxial Si films grown at 600 °C were characterized by various methods, including transmission electron microscopy, atomic force microscopy, secondary ion mass spectrometry, and selective etching. The influence of adsorbed impurities in the porous carbon material on the quality of epitaxial Si films was also investigated.

Nano cluster assisted high rate epitaxy of silicon by mesoplasma CVD

Homoepitaxial silicon thick films have been deposited by medium pressure plasma chemical vapor deposition at rates as fast as 60 nm/s at temperatures around 700 °C. X-ray scattering measurement was attempted in situ simultaneously during deposition to capture the possible cluster formation in the plasma/substrate boundary. The scattering intensity was found to increase upon injection of SiH 4 gas to Ar plasma. Such an increase in the intensity was pronounced when the epitaxial films were achieved. These potentially suggest that nano sized Si clusters were formed in the boundary region and contributed effectively to the high rate epitaxial growth.

High rate epitaxy of silicon thick films by medium pressure plasma chemical vapor deposition

Homoepitaxial silicon thick films have been produced by medium pressure plasma chemical vapor deposition at rates as fast as 60nm∕s and at a temperature of around 700°C, with a silane gas partial pressure of 4mTorr. The continuous transition of the film structures from agglomerated to faceted columnar and to epitaxial planar structure was observed with an increase in the plasma power. The calorimetric analysis during deposition has also confirmed that the thermal boundary layer thickness between the plasma and substrate reduced with the increasing power and became comparable to the mean free path of the vapors when epitaxy was achieved at high rates. In addition, the rate for epitaxial growth was observed to increase linearly with silane gas partial pressure. These potentially indicate that less coagulated silicon atom clusters formed in the reduced boundary thickness have contributed effectively to the high rate epitaxial growth.

Influence of H2/SiH4 Ratio on the Deposition Rate and Morphology of Polycrystalline Silicon Films Deposited by Atmospheric Pressure Plasma Chemical Vapor Deposition

Using the atmospheric pressure plasma chemical vapor deposition (AP-PCVD) technique, polycrystalline silicon (poly-Si) films were deposited at high rates. The plasma was generated by 150 MHz very high frequency (VHF) power. Deposition rate, morphology, and structure of the poly-Si films were studied as a function of the H2/SiH4 ratio, using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Plasma length and optical emission were also investigated to examine the reaction process in the plasma. The maximum value of deposition rate was 7.4 nm/s at an SiH4 concentration of 0.1% (H2/SiH4=100). SEM and TEM observations revealed that the poly-Si films had a columnar structure, and that the crystallites in the films deposited at high H2/SiH4 ratios contained no visible defects except at the grain boundaries. It was also shown that the Si film prepared has a preferential orientation of (220) by XRD. In addition, it was found that the plasma length was sensitive to the H2 concentration, while it was not affected by the SiH4 concentration within the deposition conditions used. This fact suggested that almost all the VHF power was consumed in the decomposition of H2 molecules.

Characterization of Epitaxial Si Films Grown by Atmospheric Pressure Plasma Chemical Vapor Deposition Using Cylindrical Rotary Electrode

Epitaxial Si films have been grown at low temperatures (500–700 °C) by atmospheric pressure plasma chemical vapor deposition using a cylindrical rotary electrode. The variation in Si film quality across the entire deposition area has been investigated. It is found that defect-free epitaxial Si growth is possible at 500 °C with sufficient plasma power in the central part of the film. At film edges, however, there are narrow regions of polycrystalline growth. From the deposition experiments under simplified boundary conditions (laminar gas flow and a uniform electric field in the plasma region), it is suggested that a large number of reactive precursors are generated when SiH4 molecules enter the plasma region, and the growth rate at the film edge on the upstream side is too high for the growth of single crystals. On the other hand, polycrystalline growth at the film edge on the downstream side is related to particle formation.