Plasma Chemical Deposition Research Articles

Direct One-Stage Plasma Chemical Synthesis of Nanostructured Thin Films of the System β-Ga<sub>2</sub>O<sub>3</sub>-GaN of Different Composition

For the first time, nanostructured thin films of the β-Ga2O3−GaN system were obtained by plasma chemical deposition from the gas phase (PECVD) on c-sapphire substrates. High-purity metallic gallium, as well as high-purity gaseous nitrogen and oxygen were used as sources of macro components. The low-temperature nonequilibrium plasma of an inductively coupled HF (40.68 MHz) discharge at a reduced pressure (0.01 Torr) was the initiator of chemical transformations between the starting substances. A mixture of oxygen and nitrogen was used as a plasma-forming gas. The plasma chemical process was studied using the optical emission spectroscopy (OES) method. The obtained thin films of the β-Ga2O3−GaN system with a GaN phase content of 2 to 7% were characterized by various analytical methods.

Plasma Chemical Deposition of Hydrogenated DLC Films with Different Hydrogen and sp3-Hybrid Carbon Content

Plasma Chemical Deposition of Hydrogenated DLC Films with Different Hydrogen and sp3-Hybrid Carbon Content

Synthesis of silicon-carbon films by induction-assisted plasma-chemical deposition

Silicon-carbon films are of great interest as diamond-like materials combining unique properties, e.g. high hardness, adhesion to a wide range of materials, abrasion resistance, chemical resistance, low friction coefficient and biocompatibility. The presence of silicon in the films significantly reduces their inner mechanical stress as compared to diamond films. Currently, the films are used in industry, primarily, as solid lubricants and protective coatings. There are a large number of silicon-carbon film synthesis methods the most widely used of which are various options of chemical vapor deposition. A new silicon-carbon film synthesis technique has been suggested and tested. The technique is based on the use of high-frequency induction for obtaining plasma of silicon and carbon vapors supplied to the reaction chamber from an external source. Impurity-free silicon-carbon films containing 63–65 % carbon atoms with sp3 orbital hybridization have been synthesized on Sitall substrates. The composition, surface roughness and friction coefficient of the impurity-free silicon-carbon films synthesized using the suggested technology have been studied. The possibility of implementing resistive switching in thin silicon-carbon films in cross-bar structures with metallic electrodes has been analyzed.

Wear of Carbide Plates with Diamond-like and Micro-Nano Polycrystalline Diamond Coatings during Interrupted Cutting of Composite Alloy Al/SiC

The complexity of milling metal matrix composite alloys based on aluminum like Al/SiC is due to their low melting point and high abrasive ability, which causes increased wear of carbide tools. One of the effective ways to improve its reliability and service life is to modify the surface by plasma chemical deposition of carbon-based multilayer functional layers from vapor (CVD) with high hardness and thermal conductivity: diamond-like (DLC) or polycrystalline diamond (PCD) coatings. Experiments on an indexable mill with CoroMill 200 inserts have shown that initial tool life increases up to 100% for cases with DLC and up to 300% for multilayered MCD/NCD films at a cutting speed of 800 m/min. The primary mechanism of wear of a carbide tool in this cutting mode was soft abrasion, when wear on both the rake and flank surfaces occurred due to the extrusion of cobalt binder between tungsten carbide grains, followed by their loss. Analysis of the wear pattern of plates with DLC and MCD/NCD coatings showed that abrasive wear begins to prevail against the background of soft abrasion. Adhesive wear is also present to a lesser extent, but there is no chipping of the base material from the cutting edge.

Creattion of silicon-carbon films by induction assisted plasma chemical deposition

Silicon-carbon films are of great interest as diamond-like materials combining unique properties – high hardness, adhesion to a wide class of materials, abrasion resistance, as well as chemical resistance, low coefficient of friction and biocompatibility. The presence of silicon in the composition makes it possible to significantly reduce the internal mechanical stresses in such coatings compared to diamond ones. In modern production, films have been used primarily as solid lubricants and protective coatings. There are a large number of methods for producing silicon-carbon films, the most widespread among which are various variants of vapor-phase chemical deposition. In this paper, a method for the synthesis of silicon-carbon films was proposed and tested, based on the use of a high-frequency inductor to produce a plasma of vapors of silicon-carbon liquid injected into the chamber from an external source. Pure silicon-carbon films with a carbon atom content with sp3-hybridized orbitals of 63–65 % were obtained on sitall substrates. The composition, surface roughness and coefficient of friction of unalloyed silicon-carbon films obtained by the proposed method were studied. The possibility of resistive switching in thin silicon carbon films in crossbar structures with metal electrodes was studied.

Field Frequency Variation during Plasma-Chemical Deposition of Silicon-Carbon Films as a Method for Their Structural Modification

The influence of the electric field frequency in the range from 0.1 to 2.0 MHz during plasma-chemical deposition of diamond-like silicon-carbon films on their chemical composition, structure, and electrical properties has been studied. It is shown that the films obtained in the entire studied frequency range have an amorphous structure with a constant, within the measurement precision, chemical composition. At the same time, the morphology of the surface of the films and their electrophysical properties significantly depend on the frequency of the electric field during plasma-chemical deposition. This makes it possible to use the change in the field frequency in the preparation of films as a method of controlling their properties. The frequency range providing the most effective modification of electrophysical properties is determined.

Field-Frequency Variation during Plasma-Chemical Deposition of Silicon–Carbon Films as a Method for Their Structural Modification

Field-Frequency Variation during Plasma-Chemical Deposition of Silicon–Carbon Films as a Method for Their Structural Modification

Modeling the processes of formation of defects that form deep levels in SiON/AlGaN/GaN

The effect on the electrical parameters of the SiON/AlGaN/GaN structures of treatment of different durations of low-energy nitrogen plasma was studied. The AlGaN surface was subjected to plasma treatment in the working chamber of the plasma-chemical deposition unit before starting the monosilane to form the SiON film. Changes in the transport properties (conductivity and mobility) of the canal and capacitive properties of the structures were evaluated. It has been experimentally shown that such treatment leads to a change in the magnitude of polarization charges both at the insulator-AlGaN interface and at the AlGaN/GaN interface. With the help of C–V measurements-in the hysteresis mode, it is shown that at the control voltage U > +4 — +5 V ), some of the channel electrons are captured at deep centers at the SiON-AlGaN interface, and with an increase in the duration of exposure to plasma time, a sharp increase is observed charge Qit, formed by electronic boundary states. The use of additional treatment with nitrogen plasma transfers work for nitride structures from the D-mode (Vth = –4 V) to the E-mode (Vth = +0.9 V).Using Auger-measurements, it was shown that plasma treatment leads to a change in the amount of oxygen in the SiON layer and in nano-regions of the barrier layer, and with an increase in the duration of plasma exposure, a sharp decrease in the amount of oxygen in these layers is observed. Also, when using plasma treatment, the redistribution of Ga and Al at the AlGaN–GaN interface i.e. in the channel area. Using Auger measurements near the SiON–AlGaN interface from the side of the insulator, the localization of nitrogen atoms chemically bonded with silicon N(Si) with the formation of a peak at the interface, the size of which increases with increasing duration of plasma exposure.

Antibiofouling Slippery Liquid Impregnated Pulsed Plasma Poly(styrene) Surfaces

AbstractBiofouling is a major global environmental and economic challenge wherein organisms settle on solid surfaces submerged in natural waters. This leads to the spread of invasive marine species around the globe, accelerates surface deterioration through microbially‐induced corrosion, and inflates maritime vessel fuel consumption which leads to greater greenhouse gas emissions. In this study, pulsed plasma poly(styrene) nanocoatings impregnated with eco‐friendly liquids are produced that yield slippery surfaces through aromatic–aliphatic intermolecular interactions (water droplet contact angle hysteresis and sliding angle values ≈1–2°). The antibiofouling performance of these slippery surfaces is demonstrated using laboratory‐based marine bioassays and real‐world field trials in freshwater (pond water) and seawater (ocean) environments. Low‐cost and substrate‐independent pulsed plasmachemical deposition combined with eco‐friendly liquid impregnation provides a sustainable approach to tackling environmental biofouling.

Fabrication of plane-type axon guidance substrates by applying diamond-like carbon thin film deposition

This research aims to fabricate plane-type substrates for evaluating the axon behaviors of neuronal cells in vitro toward the development of brain-on-chip models by applying the functions of diamond-like carbon (DLC) thin film deposition, which helped to eliminate the costly and time-consuming lithography process by utilizing a shadow mask. The DLC thin films were partially deposited on stretched polydimethylsiloxane (PDMS) substrates covered with a metal mask by the plasma chemical vaper deposition method, and using the substrates culture teats with human neuroblastoma cells (SH-SY5Y) were performed. Three patterns of interconnection structures of axons were created on the substrates with disordered and regular linear wrinkle structures with several μm size formed by the depositions. The patterns were characterized by the structure that the aggregations of axons formed on the linear DLC thin film deposited areas were separately placed in regular intervals and connected each other by plenty of axons, which were individually taut in a straight line at about 100 to over 200 μm in length. The substrates expected of uses for evaluation of axon behaviors are available without fabricating guiding grooves by conventional soft lithographic methods requiring multiple stages and their treating times.

Gd-doped silica fiber fabricated using surface plasmachemical deposition with view to radiation sensor applications

A Gd3+-doped-silica optical fiber free of other codopants in the core was fabricated with the help of surface plasma chemical vapor deposition (SPCVD) for the first time. The SPCVD-process parameters are described as well as the fiber properties in the as-drawn state (absorption and photoluminescence (PL) spectra upon excimer-laser excitation at λ = 276 and 193 nm and PL decay kinetics) and during γ-irradiation at 1–3.5 Gy/s up to 0.5–1.4 kGy (radiation-induced absorption (RIA) and radioluminescence (RL)). The 315-nm RL band is argued to be suitable for real time dose-rate monitoring, although RIA and persistent luminescence can influence the RL intensity. The possibility to suppress RIA on completion of irradiation by thermal annealing at 500 °C during 15 min was demonstrated.

Полученные плазменно-химическим осаждением a-C : ND покрытия: взаимосвязь эмиссионных свойств и фазового состава

The coatings comprised of the nanodiamond-based and amorphous-carbon-based phases (a-C:ND coatings) are investigated. The a-C:ND coatings were synthesized by chemical vapor deposition in the arc discharge plasma (by plasma chemical deposition) at various concentrations of Ar/H2/CH4. Raman spectroscopy showed that, apart from the diamond substructure, studied coatings contain amorphous-carbon-based and polyene-based phases, while diamond phase is passivated by hydrogen to different degrees. The interplay between the deposition parameters and materials' structure is analysed. It was shown that the ordering of the amorphous substructure and the formation of the phase boundaries affect the electron transport and secondary electron emission properties. The subject of the investigation of the true secondary electron spectra for the analysis of the nanostructured carbon materials is analysed. It was shown that the change of the polyene fraction in the structure of the samples leads to the variation of the ratio of field emission and thermionic emission. The influence of the structure and phase composition of the samples on their electron emission properties is investigated. In particular, their effect on the turn on-field, which value varied in the 9-18 V/μm range for the studied samples, is analysed.

Composition and optical properties of amorphous plasma-chemical silicon oxynitride of variable composition a-SiO-=SUB=-x-=/SUB=-N-=SUB=-y-=/SUB=- : H

The a-SiOxNy : H films of various compositions were obtained by plasma chemical deposition from a gas mixture of 10% monosilane (diluted with argon) and nitrogen in the presence of residual oxygen in the working gas mixture. The nitrogen flow rate varied in the range from 4 to 6 cm3/min, the power of the high-frequency generator (13.56 MHz) varied in the range of 50-150 Watts. The electronic structure and optical properties of the films were studied using X-ray photoelectron spectroscopy, vibrational spectroscopy, transmission and reflection spectroscopy, and spectral ellipsometry. It is shown that, as the generator power decreases, the content of excess silicon in the films increases and amorphous silicon nanoclusters appear. As the generator power increases, the oxygen concentration in the films decreases. Apparently, this is due to the greater dissociation of molecular nitrogen with an increase in the power of the plasma discharge and an increase in the concentration of active nitrogen. Thus, it is possible to control the composition of aa-SiOxNy : H films not only by changing the nitrogen flow, but also by varying the generator power. Keywords: silicon oxynitride, plasma-chemical deposition, stoichiometric composition, Si nanoclusters.

A-C : ND coatings obtained by plasma chemical deposition: interplay between field emission properties and phase composition

a-C : ND coatings obtained by plasma chemical deposition: interplay between field emission properties and phase composition

Состав и оптические свойства аморфного плазмохимического оксинитрида кремния переменного состава a-SiO-=SUB=-x-=/SUB=-N-=SUB=-y-=/SUB=- : H

The SiOxNy:H films of various compositions were obtained by plasma chemical deposition from a gas mixture of 10% monosilane (diluted with argon) and nitrogen in the presence of residual oxygen in the working gas mixture. The nitrogen flow rate varied in the range from 4 to 6 cm3/min, the power of the high-frequency generator (13.56 MHz) varied in the range of 50-150 Watts. The electronic structure and optical properties of the films were studied using X-ray photoelectron spectroscopy, vibrational spectroscopy, transmission and reflection spectroscopy, and spectral ellipsometry. It is shown that, as the generator power decreases, the content of excess silicon in the films increases and amorphous silicon nanoclusters appear. As the generator power increases, the oxygen concentration in the films decreases. Apparently, this is due to the greater dissociation of molecular nitrogen with an increase in the power of the plasma discharge and an increase in the concentration of active nitrogen. Thus, it is possible to control the composition of a SiOxNy:H films not only by changing the nitrogen flow, but also by varying the generator power.

Гомогенное зародышеобразование при лазерно-плазмохимическом синтезе твердых покрытий SiCN из гексаметилдисилазана

Using a differential aerosol spectrometer (DSA), a study was made of the homogeneous formation of solid phase nuclei in the process of laser-plasmochemical deposition of SiCN from hexamethyldisilazane vapor in a flow of plasma-forming argon gas. It was found that the characteristic size of SiCN nanoparticles in the gas phase is in the range of 20–120 nm and depends on the HMDS vapor concentration and the total argon flow rate. The studies performed have shown that the formation of a layer of silicon carbonitride in laser plasma-chemical deposition proceeds with the formation of nuclei in the gas phase, and upon their collision with the substrate and activation by laser plasma, it leads to the formation of a solid nanostructured coating.

Plasma-chemical deposition of diamond-like coatings in capacitively coupled RF plasma in toluene

Experimental study of the rates of plasma-chemical deposition of diamond-like coatings in toluene vapour in capacitive RF discharge was carried out. It is shown that in the RF power range of 100-300 W, the deposition rate is mainly affected by the toluene pressure in the vacuum chamber. The maximum deposition rate obtained was 4.15 μm/h.

ВЛИЯНИЕ ПАССИВИРУЮЩЕГО ПОКРЫТИЯ НА СТРУКТУРУ АЛЮМИНИЕВОЙ МЕТАЛЛИЗАЦИИ НА КРЕМНИИ

The surface quality of the metallized contact pads on the crystal plays an important role in the production of semiconductor devices. This paper presents experimental studies of the effect of a protective passivation film of silicon oxide on the surface structure of aluminum metallization in the field of forming contact pads. Plasma chemical deposition of passivation layer SiO2 from gas phase (PECVD method) was carried out on prepared samples of silicon with aluminum metallization using a high-frequency power source with a frequency of 13.56 MHz. After that, chemical etching of precipitated silicon oxide was carried out to simulate the process of forming contact areas of semiconductor device crystals. The resistance of the metallization surface to plasma processes was studied by raster electron microscopy. It is shown that as a result of the process cycle, defects of the dislocation type are generated in the applied film Al. The nature of the observed defects has been found to be different. The revealed large square-shaped pits with a size of ~ 1 μm at the places where dislocations come to the surface are of a single nature and appear independently of the processes of applying passivation coatings, which is determined by the orienting action of a single-crystal substrate having some low dislocation density. While the second type of defects, shown by the presence of etching pits measuring ~ 100-300 nm, is characterized by a higher surface density. Moreover, the exclusion of the passivation process with silicon oxide did not lead to the appearance of this type of defects, which determined their nature associated with the ion bombardment of the Al layer during the plasma chemical deposition of silicon oxide from the gas phase. It is also shown that a feature of this type of defects is their disorientation both with respect to the first type of defects and with respect to each other. Detection of the structure of the metallization layers was carried out by X-ray diffraction, the results of which show the polycrystallinity of the formed aluminum metallization. The preferred orientation of the aluminum film corresponds to the substrate Si (111).

Plasma enhanced chemical vapor deposition of gallium phosphide at low temperature

This article is devoted to the formation and study of the properties of amorphous gallium phosphide layers obtained by plasma-chemical deposition at a temperature of 250 °C. The optical and structural properties of the obtained layers on fused silica and silicon substrates were investigated. The possibility of the formation of a homogeneous amorphous gallium phosphide with a smooth surface at a low temperature and low power of RF plasma was shown.

Influence of PECVD features of SiNx deposition processes on electrical parameters of SiNx/AlGaN/GaN structures

In this work, we studied the influence of the processes of plasma-chemical deposition of SiNx films on the electrical parameters of the dielectric/AlGaN/GaN structure. The effect of the composition of the formed films, the effect of additional surface treatment of heterostructures in nitrogen plasma prior to dielectric deposition, as well as the effect of the RF bias supply during this treatment on the C-V and I-V characteristics of the SiNx/AlGaN/GaN structures were analyzed. It was found that for films with a ratio of nitrogen and silicon concentrations of 60 % and 40 %, as well as with an increased oxygen content, a decrease in the value of a fixed positive charge in these structures is characteristic, but the appearance of current pulsations is observed on the I-V characteristics of the structures. It was revealed how the modes of the plasma chemistry process affect such parameters of oscillations as the period, amplitude, length of the section of the I-V characteristic, where oscillations are observed. A possible explanation of the reasons for the appearance of characteristic pulsations is proposed. It has been established that the additional action of nitrogen plasma on the surface of the heterostructure before the monosilane is introduced into the chamber leads to a change in the magnitude and sign of the fixed charge and to a decrease in the concentration of free carriers in the channel of a two-dimensional gas of SiNx/AlGaN/GaN heterostructures. It is shown experimentally how the technological features of the deposition and surface preparation processes can affect the electrical parameters of the formed heterostructures.