Rf Plasma Chemical Vapor Deposition Research Articles

Low-stress diamond-like carbon films containing carbon nanoparticles fabricated by combining rf sputtering and plasma chemical vapor deposition

Carbon nanoparticles (CNPs) incorporated diamond-like carbon (DLC) films have been fabricated by a combination of rf sputtering and plasma chemical vapor deposition. Spherical CNPs with a mean size of 21.2 nm are sandwiched between DLC layers with a mass density of 1.7 g cm−3. The film stress is decreased to 119 MPa, by depositing the CNPs over the base DLC layer at a surface coverage of 10.7%. This reduction is approximately half of that without CNPs. Raman spectroscopy indicates the insertion of CNPs barely alters the bonding structure of the upper DLC layer.

Process optimization of graphene growth in a roll-to-roll plasma CVD system

A systematic approach to mass-production of graphene and other 2D materials is essential for current and future technological applications. By combining a sequential statistical design of experiments with in-situ process monitoring, we demonstrate a method to optimize graphene growth on copper foil in a roll-to-roll rf plasma chemical vapor deposition system. Data-driven predictive models show that gas pressure, nitrogen, oxygen, and plasma power are the main process parameters affecting the quality of graphene. Furthermore, results from in-situ optical emission spectroscopy reveal a positive correlation of CH radical to high quality of graphene, whereas O and H atoms, Ar+ ion, and C2 and CN radicals negatively correlate to quality. This work demonstrates the deposition of graphene on copper foil at 1 m/min, a scale suitable for large-scale production. The techniques described here can be extended to other 2D materials and roll-to-roll manufacturing processes.

Diamond-like carbon films from CO source gas by RF plasma CVD method

Diamond-like carbon (DLC) films were fabricated by RF CO plasma chemical vapor deposition (CVD) to avoid hydrogen incorporation into the deposited films. Broadband optical emissions confirmed a hydrogen-free process without atomic hydrogen emissions. The fabricated films were characterized by Raman scattering spectroscopy, Rutherford backscattering spectrometry (RBS) with elastic recoil detection analysis (ERDA) methods, and FT-IR spectroscopy with comparison to conventional DLC films fabricated from C2H2 gas. The hydrogen concentration in the DLC films was reduced to 4 at. % using a CO source while the conventional DLC films prepared from C2H2 contained 27 at. %. The DLC films made from CO gas contained a large amount of oxygen, approximately 20 at. %, a larger number of graphite structures than the conventional DLC film, and characteristic triple bonds (C≡C) of carbon atoms in the FT-IR spectrum.

Fabrication of diamond-like carbon-based two-dimensional photonic crystals

In this paper, we discuss the development of a process for fabricating diamond-like carbon (DLC)-based two-dimensional photonic crystals with a wider electronic bandgap and better thermostability than silicon (Si), which is used widely in nanophotonics. In the developed process, the DLC film was deposited on an Si substrate by RF plasma chemical vapor deposition, and the refractive index of the film could be changed from 1.8 to 1.95 by varying the RF power. We also theoretically show that a wide photonic bandgap can be obtained with these DLC-based photonic crystals, even though they have a low refractive index compared to pure diamond. Finally, we develop a process for fabricating DLC-based photonic crystal structures by using electron-beam lithography and inductively coupled plasma (ICP) etching techniques.

Spectroscopic studies on nanocrystalline silicon thin films prepared from H2-diluted SiH4-plasma in inductively coupled low pressure RF PECVD

A comprehensive analysis on the evolution of the microstructure as well as optical constants and dielectric functions of intrinsic hydrogenated nano-crystalline silicon thin films prepared by highly H2 diluted SiH4 plasma in a planar inductively coupled RF plasma chemical vapor deposition (ICP-CVD) reactor has been performed by spectroscopic ellipsometry. Films are assumed to have a three-layer structure, with a thin incubation layer at substrate/bulk interface, the bulk layer and a thin growth zone and surface roughness layer. Individual composition and the thickness of each layer have been estimated from the simulation of the ellipsometry data using Bruggeman effective medium approximation (BEMA). The ellipsometry results are correlated with atomic force microscopy and micro-Raman data of these films. The effect of the flow rate of SiH4 and the key role of hydrogen dilution on growth dynamics, optical constants and dielectric functions of highly crystalline nanosilicon films is discussed elaborately. The bulk crystalline volume fraction of the deposited films varies considerably (~67–84%) with the change in flow rate of SiH4. With increasing SiH4 flow rate the overall bulk crystallinity reduces; however the ultra-nanocrystalline component (Xunc) enhances substantially that helps reducing the porosity and surface roughness.

Deposition of Boron Nitride Films using RF Plasma CVD Method

Recently, as a great demand for high-strength and high-hardness materials is rising, improvement in performance of tools which manufacture those materials is being needed. Generally, tools to manufacture such materials are given high-hardness coating. Diamond and DLC (diamond like carbon) film are regarded as typical high-hardness materials, though, they can't be given to iron tools because carbons contained in them have high reactivity to iron. Consequently, the boron-nitride film which doesn't contain any carbons is expected as a coating material which can be adapted to iron tools. In this research, we prepared boron-nitride thin films on Si substrate using RF plasma CVD (chemical vapor deposition) method apparatus with a gas mixture of argon, nitrogen and trimethylborate (TMB: B(OCH3)3).

X-ray reflectivity analysis on initial stage of diamond-like carbon film deposition on Si substrate by RF plasma CVD and on removal of the sub-surface layer by oxygen plasma etching

The multi-layered structure of thin diamond-like carbon (DLC) films was investigated by X-ray reflectivity (XRR) analysis. Thin DLC films were deposited on Si substrate by RF plasma chemical vapor deposition (CVD) from acetylene source gas with short duration of plasma operation from 0.08 to 4.99s. It was confirmed from XRR analysis that the thin DLC film on Si substrate had 3 layers consisting of a subsurface layer on the grown surface, a mixing layer at the interface to Si substrate, and a bulk-DLC layer sandwiched between the 2 layers. The 3 layers had been formed in 0.08s at beginning of deposition with distinctive bulk-DLC layer of 1.7nm thick already appeared due to extremely higher deposition rate only at the initial stage of CVD. The thickness of bulk-DLC layer increased with increasing CVD duration while both the mixing layer of higher density and the sub-surface layer of extremely low density continuously existed. By oxygen plasma etching, it was confirmed by XRR analysis that the sub-surface layer was clearly removed and another layer of lower density than the bulk DLC appeared.

RF plasma chemical vapor deposition of SiN x :H films

This paper reports on the growth of hydrogenated silicon nitride films by plasma enhanced chemical vapor deposition in the temperature range 100–200°C. We examine the effect of deposition parameters on the growth kinetics, composition, and properties of the films and describe examples of the use of such films in the fabrication of uncooled IR photodetectors, antireflection coatings of solar cells, and three-dimensional microsystems.

Formation of Nanofibers on the Surface of Diamond-Like Carbon Films by RF Oxygen Plasma Etching

Diamond-like carbon (DLC) nanosize fibers were formed by etching DLC films using RF O2 plasma. The DLC films were grown on silicon substrates by an RF plasma chemical vapor deposition (CVD) method, and a small amount of Ni was deposited on the DLC films using a DC magnetron sputtering method before the etching. DLC fibers of 20 nm diameter and 600 nm height were found on the etched surfaces of the DLC films. DLC fibers of similar size that were highly insulating were also obtained by O2 etching without the deposition of Ni. It was found that Al from the RF electrode was sputtered and contaminated the DLC surface during etching, which would have affected the formation of fibers. The anisotropic etching of DLC and the ion-induced growth of carbon fibers are discussed as the formation mechanisms of the DLC fibers. The DLC fibers bent and stuck together during a field-emission scanning electron microscope observation, especially in the slow scanning mode. Such soft fibers can exist vertically and straightly throughout the etching in RF plasma.

713 窒素含有アモルファスカーボン半導体の電気的特性(OS7-(4)オーガナイズドセッション《精密/微細加工と評価》)

This paper presents an investigation of the influence of nitrogen addition on the electrical properties of diamond-like carbon (DLC) films on glass substrates using RF plasma chemical vapor deposition, the respective Hall effect of the DLC films were evaluated and compared as a function of Nitrogen concentration. And film composition and atomic bond structure were characterized using Raman spectroscopy and XPS. Hall effect measurement revealed that the difference by nitrogen concentration of specific resistance are expressed as a function of the carrier density and the carrier mobility respectively. Considering the results of Raman spectroscopy and XPS revealed that the sp3 bond in the DLC film increases with increasing nitrogen concentration. Thus, it was suggested that the electrical properties and semiconductor properties of DLC films depend on the sp2/sp3 fraction in the films.

Evaluation of Thermoelectric Conversion Performance of the Nitrogen-Containing Diamond Like Carbon Thin Films

This paper presents an investigation of the influence of nitrogen addition on the thermoelectric conversion performance of diamond-like carbon (DLC) films on glass substrates using RF plasma chemical vapor deposition. The respective thermoelectric conversion performances and Hall effect of the DLC films were evaluated and compared as a function of Nitrogen concentration. And film composition and atomic bond structure were characterized using Raman spectroscopy and XPS. At temperature of 473.2K, absolute value of Seebeck coefficients of the DLC films decreased concomitantly with increasing nitrogen concentration at 0—4.0at.%. However, the Seebeck coefficients of 4.0—8.1at.% were almost identical. At temperature at 298.2K, the Seebeck coefficients of 0—8.1at.% were almost identical regardless of the concentration of nitrogen. At temperature of 298.2K, specific resistance of the DLC films decreased concomitantly with increasing nitrogen concentration at 0—4.0at.%. However, the specific resistance of 4.0—8.1at.% was almost identical. The power factor of the DLC films increased concomitantly with increasing nitrogen concentration below the temperature of 398.2K. Hall effect measurements revealed that the difference by nitrogen concentration of Seebeck coefficient and specific resistance are expressed as a function of the carrier density and the carrier mobility respectively. Considering the results of Raman spectroscopy and XPS revealed that the sp3 bond in the DLC film increases with increasing nitrogen concentration. Thus, it was suggested that the electrical properties and semiconductor properties of DLC films depend on the sp2/sp3 fraction in the films.

714 DLC被膜の熱電性能に及ぼす窒素含有率の影響(OS7-(4)オーガナイズドセッション《精密/微細加工と評価》)

Nitrogen doped diamond like amorphous carbon (DLC) thin films on grass substrate were prepared by rapid frequency (rf) plasma chemical vapor deposition (CVD) using CH_4 as the source of carbon and with different N_2 flow rates (N2 : CH4 gas ratios between 0 : 100 and 30 : 70) ,at about 230 〜300K. The resistivity of the film were measured by Van der pauw method. The nitrogen content in the films was about 3.8-6.0%, obtained from Glow discharge optical emission spectroscopy. The thermoelectric performance of nitrogen doped DLC was increased step by step with increasing nitrogen flow rate. The difference of thermoelectric performance was decreased with the increase temperature.

311 DLC被膜の熱電性能に及ぼす窒素含有率の影響(OS3-(3)オーガナイズドセッション《環境とエネルギー》)

Nitrogen doped diamond like amorphous carbon (DLC) thin films on grass substrate were prepared by radio frequency (rf) plasma chemical vapor deposition (CVD) using CH4 as the source of carbon and with different N_2 flow rates (N2 : CH4 gas ratios between 0 : 100 and 40 : 60), at 270〜300K. The resistivity of the film were measured by Van der pauw method. The nitrogen content in the films was about 3.8-6.0%, obtained from Glow discharge optical emission spectroscopy. The thermoelectric performance of nitrogen doped DLC was increased step by step with increasing nitrogen flow rate. The difference of thermoelectric performance was decreased with the increase temperature.

Cytocompatibility of modified a-C:H film deposited on complicated polymeric medical apparatus

In this study, in order to biologically evaluate the surface condition of the a-C:H film which was deposited on a complicated polymeric medical apparatus by using rf plasma chemical vapor deposition technique with a special three-dimensional-type electrode, we have investigated the cytocompatibility to the a-C:H film with and without plasma post-treatment. The a-C:H film surface was modified with argon (Ar) and oxygen (O2) plasma post-treatment to change the surface condition of the a-C:H film. The effects of the plasma post-treatment of a-C:H film deposited on a complicated object were estimated by using an Ar-laser Raman microscopy (Raman), a wettability measurement, a x-ray photoelectron spectrometer, and an atomic force microscopy. Additionally, the cellular adhesions of a-C:H film with and without plasma post-treatments were carried out under cell culture by in vitro studies. As results, The surface properties of a-C:H film on a complicated polymeric medical apparatus were controlled by surface modifications with Ar and O2 plasma post-treatment. Additionally, the cell cultures by in vitro studies have shown good cell growth on all the a-C:H film surface. Moreover, it was observed that cellular growth/adhesion was controlled by surface conditions of the a-C:H film with and without plasma post-treatments.

Tribological Properties of Segment-Structured DLC Films Coated on Stainless Steel Substrate

Diamond-like carbon (DLC) films have low friction coefficient against variety of materials and high wear resistance; however, DLCs are often damaged when the DLC film is distorted with deformation of the substrate. Segment-structured DLC (S-DLC) coating has been developed to improve these weak points of DLC films. The S-DLC coating is a technique to separate the DLC film into the small segments. The purpose of this study is to fabricate S-DLC film on stainless steel substrate and functionalize DLC films on the substrate based on S-DLC film. In this study, fluorocarbon polymer embedded segment-structured DLC (FC-S-DLC) film was fabricated by spraying fluorocarbon polymer into the grooves between the DLC segments. The DLC films were deposited by a RF plasma chemical vapor deposition (CVD) method. Evaluations of tribological properties of these high-functional DLC films were performed under plane contact condition by pin-on-disk (PoD) test. As a result, the S-DLC film exhibited better tribological properties than that of continuous DLC film. Furthermore, the FC-S-DLC coating exhibited the most excellent tribological property among all samples and gave high wear resistance and steady friction coefficient to stainless steel substrates at a plane contact pressure of 0.16∼0.24MPa.

Effect of film chemistry on refractive index of plasma-enhanced chemical vapor deposited silicon oxynitride films: A correlative study

Thick SiOxNy films were deposited by radiofrequency (rf) plasma chemical vapor deposition using silane (SiH4) and nitrous oxide (N2O) source gases. The influence of deposition conditions of gas flow ratio, rf plasma mixed-frequency ratio (100 kHz, 13.56 MHz), and rf power on the refractive index were examined. It was observed that the refractive index of the SiOxNy films increased with N and Si concentration as measured via x-ray photoelectron spectroscopy. Interestingly, a variation of refractive index with N2O:SiH4 flow ratio for the two drive frequencies was observed, suggesting that oxynitride bonding plays an important role in determining the optical properties. The two drive frequencies also led to differences in hydrogen concentration that were found to be correlated with refractive index. Hydrogen concentration has been linked to significant optical absorption losses above index values of ∼1.6, which we identified as a saturation level in our films.

Optical and Electrical Properties of Organic Films Prepared by RF Plasma Chemical Vapor Deposition Using Mixed Naphthalene and Propane Source

Organic films were prepared by RF plasma chemical vapor deposition (CVD) using naphthalene (named naph), propane (prop), and naphthalene mixed propane (naph-prop). All of the samples showed broadband emission of photoluminescence. In IR transmission, aromatic ring out-of-plane C–H bending, C–H stretching, and C=C stretching vibrations were observed in naph-prop sample, and all of the absorption was similar to naph sample. The aliphatic C–Hn stretching vibrations also were founded in all samples. The conductivity of the naph-prop sample was 1.8 ×10-7 S/cm, and this value was large compared to the samples that only prepared by naphthalene or propane. The naph-prop sample showed the space charge limited current (SCLC) at the higher voltage region.

Plasma enhanced chemical vapor deposition of palladium in anodic aluminum oxide template

Abstract High quality AAO templates were fabricated using multi-step electrochemical process. The formation of well ordered pores having dimensions of 50–100 nm diameters and up to 2000 nm depths, could be achieved. The effect of processing time, voltage during anodization, etc. have been studied. The freshly fabricated AAO templates are used to deposit palladium films using RF-plasma chemical vapor deposition using palladium hexafluro-acetylacetonate [Pd(C 5 HF 6 O 2 ) 2 ], as a precursor material. The samples were characterized by using high resolution scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), glancing angle X-ray diffraction etc. It is observed that the conformal coatings of palladium could be achieved in AAO pores, which could subsequently be utilized for many applications where in catalytic behavior of palladium is utilized.

N and p-type doping of PECVD a-SiC:H obtained under “silane starving plasma” condition with and without hydrogen dilution

N and p-type doping of highly structural and chemically ordered a-Si 0.5C 0.5:H films are studied. Ion implantation is utilized as doping technique and the films are obtained by rf plasma chemical vapor deposition (PECVD) in the so-called “silane starving plasma” condition, which plays an important role to improve the structural properties of a-SiC:H films. Since hydrogen plasma improves even more the structural properties of the material, the doping efficiency is studied in two types of a-Si 0.5C 0.5:H samples grown with and without hydrogen dilution of the precursor gaseous mixture. For n-type doping, phosphorus was implanted in concentrations varying between 10 18 and 10 21 cm −3, according to previous theoretical simulations. For p-type doping boron and, for the first time in a-SiC:H technology, boron difluoride (BF 2) were implanted, both with a fixed concentration of 10 20 cm −3. The electrical characterization for phosphorus doping shows that the conductivity of the films increases with increasing impurity concentration and, in the best case a room temperature dark conductivity of ∼10 −4 (Ω cm) −1 and an dark conductivity activation energy of 0.1 eV were obtained. For p-type doping the results indicate that BF 2 + is much more efficient than boron, which is related to the production of a shallow doped layer, in accordance to observations in c-Si. In this way a p-type dark conductivity of ∼10 −1 (Ω cm) −1 and energy of 20 meV were obtained.

Dielectric Properties of BaTiO3 Films Prepared by RF-Plasma Chemical Vapor Deposition

The size dependence of the dielectric properties of BaTiO3 nano-grains was investigated using films prepared by RF-plasma chemical vapor deposition. BaTiO3 nanoparticles were directly deposited on Pt/Al2O3/SiO2/Si substrates; then they were annealed at temperatures between 600 and 900°C in order to control the grain size. The dielectric constants of BaTiO3 nano-grains smaller than 30 nm were measured to be 200–300, and reached approximately 1000 for grain sizes of 50–60 nm. According to capacitance–voltage (C–V) curves and hysteresis loops, the phase transformation from paraelectric to ferroelectric occurred at a grain size of approximately 40 nm. The dielectric constants of the films were considerably stable against the temperatures ranging from 5 to 160°C, even though the dielectric constants were approximately 1000. The breakdown electric fields of the films increased with decreasing grain sizes and a value of 649 kV/cm was achieved at a grain size of 27 nm.