Remote Hydrogen Microwave Plasma Research Articles

Hard silicon carbonitride thin‐film coatings produced by remote hydrogen plasma chemical vapor deposition using aminosilane and silazane precursors. 1: Deposition mechanism, chemical structure, and surface morphology

AbstractAmorphous silicon carbonitride films were produced by remote hydrogen microwave plasma chemical vapor deposition (RP‐CVD) using aminosilanes: (dimethylamino)dimethylsilane, bis(dimethylamino)methylsilane, and tris(dimethylamino)silane, as well as disilazanes: 1,1,3,3‐tetramethyldisilazane and 1,3‐bis(dimethylsilyl)‐2,2,4,4‐tetramethylcyclodisilazane as single‐source precursors. The effect of substrate temperature (TS) on the rate and yield of the RP‐CVD process, chemical composition, chemical structure, and surface morphology of resulting films is reported. The temperature dependencies of thickness‐based growth rate and growth yield of the film imply that for a low substrate temperature range (TS = 30–200°C), deposition rate and yield are limited by desorption of film‐forming precursors from a growth surface, whereas for a high substrate temperature range (TS = 200–400°C), the rate and yield values, independent of the temperature, are nearly constant and the RP‐CVD is a nonthermally activated process. The increase of the substrate temperature from 30°C to 400°C causes the elimination of organic groups from the film and the formation of a silicon carbonitride network structure with a predominant content of Si–N nitridic and Si–C carbidic bonds. On the basis of structural study and literature data, hypothetical elementary reactions contributing to the film formation process are postulated. The films were found to be morphologically homogeneous, defect‐free materials exhibiting very small surface roughness, which varied in a narrow range of values.

Surface modification of silicon oxycarbide films produced by remote hydrogen microwave plasma chemical vapour deposition from tetramethyldisiloxane precursor

The motivation for this contribution is the search for thin-film silicon oxycarbide (SiOC) materials suitable for modern electronics with good chemical/thermal stability, good barrier properties and conformal coverage, which can be deposited on rigid and flexible substrates, and whose surface can be organically functionalized. Two types of thin SiOC films of very different nature, such as polymer-like and ceramic-like, were fabricated by means of remote hydrogen microwave plasma chemical vapour deposition (RP-CVD) from 1,1,3,3–tetramethyldisiloxane (TMDSO). The RP-CVD coatings deposited on a silicon substrate were then modified by treatment with a direct radiofrequency (RF) plasma process induced in a mixture of argon and water vapour (Ar/H2O), which resulted in the surface activation through the formation of highly reactive silanol groups (SiOH). In this process a silicon oxide layer (SiOx) was also formed, and its growth was examined by FTIR, XPS and ellipsometry. The growth of the SiOx structure reduces the film thickness of silicon oxycarbide. Activation of the film surface is completed in <10 s. In the next modification step, the RP-CVD films were silanized by immobilizing (3-aminopropyl)triethoxysilane (APTES). Attachment of APTES molecules to the activated surface of SiOC films was observed with the development of an additional layer of SiOx on the surface. The silanization with APTES vapour under nitrogen allowed the formation of 10 nm-thick condensate. The AFM microscopic examination showed that the deposited APTES layers are homogeneous without aggregates specific for conventional silanization from the solution. The final modification of RP-CVD films was achieved by functionalization with an organic fluorescent probe, which involves the covalent attachment of pyrene to amino group of APTES using hydroxyimide ester linkage (PyNHS). The results of the present study proved that the chemical functionalization of thin silicon oxycarbide films was achieved.

Silicon Carbide, Silicon Carbonitride, and Silicon Oxycarbide Thin Films Formed by Remote Hydrogen Microwave Plasma CVD

Background: Silicon-based thin films produced by remote microwave hydrogen plasma chemical vapor deposition (RP-CVD) from 1,1,4,4-tetramethyldisilaethylene, 1,1,3,3-tetramethyldisiloxane and 1,1,3,3- tetramethyldisilazane precursors are compared. The structure of these compounds differs in atomic composition of the central unit which links the two dimethylhydrosilane moieties. Objective: The effect of temperature on the kinetics of film growth rate induced by RP CVD process, chemical composition and structure as well as same characteristic parameters of resulting amorphous hydrogenated silicon carbide (a-SiC:H), silicon oxycarbide (a-SiOC:H), and silicon carbonitride (a-SiCN:H) films is discussed. Conclusion: It was found that RP CVD process is controlled by adsorption, in which there are two temperature ranges for the formation of the CVD layers. At low-temperature range soft polymer-like material is formed containing organic groups whereas at high-temperature range a transformation to high-density ceramic- like material occurs. Based upon the results of the studies, mechanisms of the initiation step, as well as growth and crosslinking steps in the film formation during RP CVD deposition are proposed. The films were also characterized in terms of their representative properties, such as density, refractive index and biocompatibility. Owing to the high density, defect-free surface and excellent optical parameters the films may be useful as coatings for optoelectronics applications and in medicine for steel implants. Keywords: Remote hydrogen plasma, CVD process, silicon-based precursor, silicon carbide film, silicon oxycarbide film, silicon carbonitride film, properties of thin films, biocompatibility.

Silicon Oxycarbide Films Produced by Remote Microwave Hydrogen Plasma CVD using a Tetramethyldisiloxane Precursor: Growth Kinetics, Structure, Surface Morphology, and Properties

Amorphous hydrogenated silicon oxycarbide (a‐SiCO:H) thin films are produced by remote microwave hydrogen plasma CVD using 1,1,3,3‐tetramethyldisiloxane precursor. The effect of substrate temperature (TS) on the chemical structure and some properties of resulting a‐SiCO:H films is reported. The examination performed by infrared spectroscopy revealed that the increase in TS involves the elimination of organic moieties from the film and its transformation from polymer‐like to ceramic‐like high‐crosslink‐density material. Due to their small surface roughness, high density, and good optical transparency, the a‐SiCO:H films seem to be useful coatings for optical and electronic devices.

Remote hydrogen microwave plasma chemical vapor deposition from methylsilane precursors. 1. Growth mechanism and chemical structure of deposited a-SiC:H films

Amorphous hydrogenated silicon carbide (a-SiC:H) thin films were produced by remote microwave hydrogen plasma chemical vapor deposition (RP-CVD) using dimethylsilane (DMS) and trimethylsilane (TrMS) as single-source precursors. The effect of substrate temperature on the rate of RP-CVD process, chemical composition and chemical structure of resulting a-SiC:H films is reported. The Arrhenius plots of substrate temperature dependencies of the thickness-based film growth rate imply that the investigated RP-CVD for DMS precursor is a non-thermally activated process, whereas for TrMS precursor is an adsorption-controlled process. The examination of the a-SiC:H films performed by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared absorption spectroscopy, revealed that the increase in the substrate temperature from 30°C to 400°C causes the elimination of organic moieties from the films and the formation of Si-carbidic network structures. On the basis of the results of structural study the elementary reactions involved in the formation of a-SiC:H films are proposed.

Remote hydrogen microwave plasma chemical vapor deposition from methylsilane precursors. 2. Surface morphology and properties of deposited a-SiC:H films

Amorphous hydrogenated silicon carbide (a-SiC:H) films produced by remote microwave hydrogen plasma chemical vapor deposition from dimethylsilane and trimethylsilane precursors were characterized in terms of their basic useful properties including surface morphology, conformality of coverage, density, refractive index, optical absorption (absorption coefficient and optical bandgap) adhesion to a substrate, and friction coefficient. The effect of substrate temperature (varied in the range TS=30–400°C) on the properties of a-SiC:H films is reported. In view of the scanning electron microscopy and atomic force microscopy examinations the films were found to be morphologically homogeneous materials exhibiting excellent conformality of coverage and small surface roughness, which drop with rising TS to a small value of 0.9nm at TS=400°C. The relationships between the film compositional and structural parameters, expressed, respectively, by the atomic ratio Si/C, and the relative integrated intensities of the absorption IR band from the SiC bonds (controlled by TS), were determined. Due to their good conformality of coverage, strong adhesion to a substrate, very low friction coefficient, and excellent optical transparency in a wide range of wavelength a-SiC:H films produced from trimethylsilane precursor at high substrate temperature regime (TS=300–400°C) seem to be useful as scratch-resistant protective coatings for optical glass elements and various metal surfaces.

Thin a‐SiC:H Films Formed by Remote Hydrogen Microwave Plasma CVD using Dimethylsilane and Trimethylsilane Precursors

The effect of substrate temperature (TS) on the chemical structure, surface morphology, density, and adhesion to a substrate of a‐SiC:H films is reported. The increase in TS from 30 °C to 400 °C causes the elimination of organic moieties from the film and the formation of Si‐carbidic network. The films produced at high TS are morphologically homogeneous, dense, and strongly adhere to coatings.

A‐SiC:H Films by Remote Hydrogen Microwave Plasma CVD From Ethylsilane Precursors**

Amorphous, hydrogenated, silicon carbide (a‐SiC:H) films are deposited in the remote hydrogen microwave plasma (RP‐CVD) process using diethylsilane as a single‐source precursor. The effect of substrate temperature (TS) on the kinetics of RP‐CVD, chemical composition, structure, surface morphology, and properties (density, refractive index, and extinction coefficient) of the resulting a‐SiC:H films is investigated. The TS dependence of film growth rate implies that RP‐CVD is an adsorption‐controlled process. The increase of TS from 30 °C to 350 °C causes the elimination of organic moieties from the film and the formation of a SiC network structure. The relationships between the content of SiC bonds, represented by the relative integrated intensity of the SiC IR band, and the film properties are determined. The number of SiC bonds is found to be a key parameter in the control of the examined film properties. The films deposited at TS = 350 °C appear to be very dense materials exhibiting small surface roughness and high refractive index. The results of the present study are compared with those reported for a‐SiC:H films produced by RP‐CVD from a triethylsilane precursor.

Hard a-SiC:H films formed by remote hydrogen microwave plasma chemical vapor deposition using a novel single-source precursor

The a-SiC:H films were produced by remote hydrogen plasma chemical vapor deposition (RP-CVD) from bis(dimethylsilyl)ethane as a novel single-source precursor. The effect of substrate temperature (TS) on the kinetics of RP-CVD, chemical composition, structure, surface morphology, and properties of resulting films (density, refractive index, photoluminescence, hardness, elasticity, and resistance to wear) is reported. The TS dependence of film growth rate implies that RP-CVD is an adsorption controlled process. The increase of TS from 30°C to 400°C causes the elimination of organic moieties from the film and the formation of SiC network structure. The relationships between the relative integrated intensity of SiC IR band and film properties were determined. The films deposited at TS=300°C appear to be very hard materials exhibiting small surface roughness and low intensity of blue photoluminescence (PL). They seem to be suitable protective coatings for metals to increase their wear strength.

Amorphous Hydrogenated Silicon Carbide (a‐SiC:H) Coatings Produced by Remote Hydrogen Microwave Plasma CVD from Bis(dimethylsilyl)ethane ‐ a Novel Single‐Source Precursor

The effect of substrate temperature (TS) on the growth rate, chemical structure, surface morphology, density, refractive index and photoluminescence (PL) of a‐SiC:H films is reported. The increase in TS from 30°C to 400°C causes the elimination of organic moieties from the film and the formation of Si‐carbidic network structure. The films produced at high TS are morphologically homogeneous, dense, and hard materials of high refractive index and extremely low PL intensity.

Remote Hydrogen Microwave Plasma Chemical Vapor Deposition of Amorphous Silicon Carbonitride (a‐SiCN) Coatings Derived From Tris(dimethylamino)Silane

AbstractAmorphous silicon carbonitride films were produced by remote hydrogen plasma CVD (RP‐CVD) from Tris(dimethylamino)silane precursor. The effect of substrate temperature (TS) on the kinetics of RP‐CVD, chemical composition, structure, surface morphology, and properties of resulting films is reported. The TS dependence of film growth rate imply that RP‐CVD is an adsorption‐controlled process. The increase of TS from 30 to 400 °C causes the elimination of organic moieties from the film and the formation of SiC and SiN network structure. The structure–property relationships were determined. The films deposited at TS = 300 °C appear to be dense materials exhibiting very small surface roughness, high hardness, and an extremely low friction coefficient. They seem to be suitable protective coatings for metal surfaces to increase their wear strength. magnified image

Silicon Carbonitride (SiCN) Films by Remote Hydrogen Microwave Plasma CVD from Tris(dimethylamino)silane as Novel Single‐Source Precursor

SiCN films were produced by remote microwave hydrogen plasma CVD (RP‐CVD) from tris(dimethylamino)silane precursor using different substrate temperature in the range TS=30‐400°C. The effect of TS on the rate of RP‐CVD, chemical structure, surface morphology, density, and photoluminescence (PL) of resulting films is reported. The increase in TS causes the formation of silicon carbonitride network, marked densification and smoothening of film surface, as well as shift of PL peak position.

Growth Mechanism and Chemical Structure of Amorphous Hydrogenated Silicon Carbide (a‐SiC:H) Films Formed by Remote Hydrogen Microwave Plasma CVD From a Triethylsilane Precursor: Part 1

AbstractAmorphous hydrogenated silicon carbide (a‐SiC:H) films are produced by remote microwave hydrogen plasma (RHP)CVD using triethylsilane (TrES) as the single‐source precursor. The reactivity of particular bonds of the precursor in the activation step is examined using tetraethylsilane as a model compound for the RHP‐CVD experiments. The susceptibility of a TrES precursor towards film formation is characterized by determining the yield of RHP‐CVD and comparing it with that of the trimethylsilane precursor. The effect of substrate temperature (Ts) on the rate of the RHP‐CVD process, chemical composition, and chemical structure of the resulting a‐SiC:H films is reported. The substrate temperature dependence of the film growth rate implies that film growth is independent of the temperature and RHP‐CVD is a mass transport‐limited process. The examination of the a‐SiC:H films, performed by means of X‐ray photoelectron spectroscopy (XPS), elastic recoil detection analysis (ERDA), and Fourier transform infrared absorption spectroscopy (FTIR), reveals that the increase in the substrate temperature from 30 °C to 400 °C causes the elimination of organic moieties from the film and the formation of a Si‐carbidic network structure. On the basis of the results of the structural study, the chemistry involved in film formation is proposed.

Properties of Amorphous Hydrogenated Silicon Carbide (a‐SiC:H) Films Formed by Remote Hydrogen Microwave Plasma CVD From a Triethylsilane Precursor: Part 2

AbstractThe surface morphology and physical (density), optical (refractive index), and mechanical (hardness, elasticity) properties of amorphous hydrogenated silicon carbide (a‐SiC:H) films produced by remote microwave hydrogen plasma (RHP)CVD from a triethylsilane precursor are investigated. The effect of substrate temperature (varied in the range Ts = 30–400 °C) on the properties of a‐SiC:H films is reported. In view of the atomic force microscopy (AFM) examination the films were found to be morphologically homogeneous materials exhibiting small surface roughness which varies with Ts in a narrow range of values (1.0–1.5 nm). The relationships between the film compositional parameter, expressed by the atomic concentration ratio Si/C, and structural parameter described by the relative integrated intensities of the absorption IR band from the SiC bonds (controlled by substrate temperature) are examined. On the basis of the results of these examinations, reasonable compositional and structural dependencies of film properties are determined. The properties of investigated a‐SiC:H films are compared with those reported in the literature for films produced from various organosilicon precursors by different CVD techniques. Due to their good mechanical properties a‐SiC:H films produced in a high substrate temperature regime (Ts = 300–400 °C) seem to be useful as protective coatings improving the surface mechanics of various engineering materials.

Hard and High-Temperature-Resistant Silicon Carbonitride Coatings Based on N-Silyl-Substituted Cyclodisilazane Rings

1,3-bis(dimethylsilyl)-2,2,4,4-tetrametyhylcyclodisilazane was used as a single-source precursor for the production of silicon carbonitride (SiCN) thin-film coatings by remote microwave hydrogen plasma chemical vapor deposition (RP-CVD). The effect of the substrate temperature on the rate and yield of the RP-CVD process, chemical composition, chemical structure, and surface morphology of the resulting film is reported. The temperature dependencies of the thickness-based growth rate and growth yield of the film imply that for the low substrate temperature range , film growth is limited by adsorption of film-forming precursors, whereas in the high substrate temperature range , film growth is independent of the temperature and RP-CVD is a mass-transport limited process. The increase of the substrate temperature from causes the elimination of organic moieties from the film and the formation of the Si–C network, which contains incorporated N-silyl-substituted cyclodisilazane molecular skeletons of the precursor linked with the network via the Si–C bonds. The microscopic examination revealed that the films are defect-free materials of excellent morphological homogeneity and exhibit small surface roughness, which vary in a narrow range of values. The SiCN films deposited at various substrate temperatures were characterized in terms of their density, adhesion to a substrate, hardness, elastic modulus, and friction coefficient. The film properties are strongly influenced by the compositional and structural parameters represented, respectively, by the contents of nitrogen and Si–C bonds; the latter described by the relative integrated intensity of the Si–C infrared band. The reasonable relationships between the film properties and the mentioned compositional and structural parameters have been determined.

Rapid Thermal Annealing and Hydrogen Passivation of Polycrystalline Silicon Thin-Film Solar Cells on Low-Temperature Glass

The changes in open-circuit voltage (Voc), short-circuit current density (Jsc), and internal quantum efficiency (IQE) of aLuminum induced crystallization, ion-assisted deposition (ALICIA) polycrystalline silicon thin-film solar cells on low-temperature glass substrates due to rapid thermal anneal (RTA) treatment and subsequent remote microwave hydrogen plasma passivation (hydrogenation) are examined. Voc improvements from 130 mV to 430 mV, Jsc improvements from 1.2 mA/cm2 to 11.3 mA/cm2, and peak IQE improvements from 16% to &gt; 70% are achieved. A 1-second RTA plateau at 1000°C followed by hydrogenation increases the Jsc by a factor of 5.5. Secondary ion mass spectroscopy measurements are used to determine the concentration profiles of dopants, impurities, and hydrogen. Computer modeling based on simulations of the measured IQE data reveals that the minority carrier lifetime in the absorber region increases by 3 orders of magnitude to about 1 nanosecond (corresponding to a diffusion length of at least 1 μm) due to RTA and subsequent hydrogenation. The evaluation of the changes in the quantum efficiency and Voc due to RTA and hydrogenation with computer modeling significantly improves the understanding of the limiting factors to cell performance.

Remote Hydrogen Microwave Plasma CVD of Silicon Carbonitride Films from a Tetramethyldisilazane Source. Part 1: Characterization of the Process and Structure of the Films

AbstractSilicon carbonitride (Si:C:N) films are produced by hydrogen remote microwave plasma (RP)CVD using a 1,1,3,3‐tetramethyldisilazane precursor. The effect of the substrate temperature on the rate and yield of the hydrogen RPCVD process, chemical composition, chemical structure, and surface morphology of the resulting film are investigated. The Arrhenius plots of the substrate temperature dependencies of the mass‐ and thickness‐based growth rate and growth yield of Si:C:N film imply that RPCVD is controlled by the adsorption of film‐forming precursors onto the growth surface. The results of Auger electron spectroscopy (AES) and Fourier transform infrared (FTIR) examinations reveal that the increase in substrate temperature from 35 °C to 400 °C involves the elimination of organic groups from the film and the formation of a silicon carbonitride network structure with a predominant content of Si‐C carbidic bonds. The atomic force microscopy (AFM) results show that the films are morphologically homogeneous materials of surface roughness varying in a narrow range of small values (0.9 – 2.0 nm).

Remote Hydrogen Microwave Plasma CVD of Silicon Carbonitride Films From a Tetramethyldisilazane Source. Part 2: Compositional and Structural Dependencies of Film Properties

AbstractThe silicon carbonitride (Si:C:N) films produced by hydrogen remote microwave plasma (RP)CVD from a 1,1,3,3‐tetramethyldisilazane precursor at various substrate temperatures (35–400 °C) are examined in terms of their physical (density), optical (refractive index), and mechanical (hardness, elastic modulus, friction coefficient) properties. The films' resistance to wear is predicted from the slope of the hardness/elastic modulus plot. Reasonable correlations between the properties of Si:C:N films and their compositional parameters (expressed by the atomic ratios C/Si, N/Si, and N/C) as well as structural parameters (represented by the relative integrated intensities of the absorption infrared (IR) bands from the Si–C and Si–N bonds) are found to exist. The effect of Si:C:N film coating on the surface mechanical properties of carbon steel and stainless steel is investigated.

Silicon carbonitride by remote microwave plasma CVD from organosilicon precursor: Physical and mechanical properties of deposited Si:C:N films

Silicon carbonitride (Si:C:N) films produced by the remote microwave hydrogen plasma chemical vapor deposition (RP-CVD) using bis(dimethylamino)methylsilane as single-source precursor and hydrogen as an upstream gas for plasma generation, were examined in terms of their physical (density) and mechanical (hardness, elastic modulus, friction coefficient, and “plasticity index”) properties. The effect of substrate temperature (varied in the range of 30–400 °C) on the properties of Si:C:N films is presented. A reasonable compositional and structural dependencies of film properties were determined using, respectively, the XPS atomic concentration ratios N/Si and C/Si, as well as the relative integrated intensities of the IR absorption bands from the Si N and Si C bonds (controlled by deposition temperature), evaluated in the first part of this work. In view of their good mechanical properties, Si:C:N films seem to be useful coatings for improving surface mechanics of engineering materials.

Silicon carbonitride by remote microwave plasma CVD from organosilicon precursor: Growth mechanism and structure of resulting Si:C:N films

The remote microwave hydrogen plasma chemical vapor deposition (RP-CVD) from bis(dimethylamino)methylsilane precursor was used for the synthesis of silicon carbonitride (Si:C:N) films. The effect of thermal activation on the RP-CVD process was examined by determining the mass- and the thickness-based film growth rate and film growth yield, at different substrate temperature ( T S). It was found that the mechanism of the process depends on T S and for low substrate temperature regime, 30 °C ≤ T S ≤ 100 °C, RP-CVD is limited by desorption of film-forming precursors, whereas for high substrate temperature regime, 100 °C < T S ≤ 400 °C, RP-CVD is a non-thermally activated and mass-transport limited process. The Si:C:N films were characterized by X-ray photoelectron and Fourier transform infrared spectroscopies, as well as by atomic force microscopy. The increase of T S enhances crosslinking in the film via the formation of nitridic Si–N and carbidic Si–C bonds. On the basis of the structural data a hypothetical crsosslinking reactions contributing to silicon carbonitride network formation have been proposed.