Tetramethylsilane Flow Research Articles

Preparation of silicon-doped diamond-like carbon films with electrical conductivity by reactive high-power impulse magnetron sputtering combined with a plasma-based ion implantation system

Silicon-doped diamond-like carbon (Si-doped DLC) films were prepared by a reactive high-power impulse magnetron sputtering (HiPIMS) combined with a plasma-based ion implantation (PBII) system, in which tetramethylsilane (TMS) was used as a reactive gas. The preparation of the Si-doped DLC films was based on both plasma-enhanced chemical vapor deposition and physical vapor deposition. The incident energy of the reactive ions was controlled by applying negative pulse voltage to the substrate using the PBII system. The Si content was controlled by the flow rate ratio of TMS to Ar. The negative pulse voltage was crucial because the resistivity of Si-doped DLC films prepared under the conditions of an Ar flow rate of 75 sccm and a TMS flow rate of 1.5sccm exponentially decreased from 575 to 30 Ωcm with an increase in the negative pulse voltage in the voltage range up to −7 kV. Through X-ray photoelectron spectroscopy, it was estimated that the Si content in the films ranged between 4.3% and 11% in our experiment. The resistivity of the films, which were prepared at a negative pulse voltage of −5 or − 7 kV in the range of the flow rate ratio up to 0.043, markedly increased from 3 to 380 Ωcm with an increase in the Si content. Moreover, the film hardness ranged between 9 and 16 GPa.

Radial distribution of C4H8–H2–TMS plasma during plasma‐enhanced chemical vapor deposition of Si‐doped glow discharge polymers

AbstractA silicon‐doped glow discharge polymer (Si‐GDP) was prepared by plasma‐enhanced chemical vapor deposition technique of mixtures of trans‐2‐butene (C4H8), hydrogen (H2), and tetramethylsilane (TMS). The plasma parameters were characterized by mass spectrometry. The film properties of Si‐GDP were investigated by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. At a TMS flow of 0.15 cm3/min, the radial distribution of the relative intensities of CH fragment ions was uniform, which indicates balanced dissociation and polymerization. As the radial distance increases, the ion energy decreases, and the ratio of sp3/sp2 carbon and the atomic ratio of Si increases. The purpose of this work was to explore correlations between C4H8/H2/TMS plasma parameters and Si‐GDP film properties.

Tetramethysilane-assisted enhancement of diamond nucleation on silicon substrate

This paper describes the effect of tetramethylsilane (TMS) on diamond nucleation on Si substrate under an applied bias voltage of 120 V, performed in a modified microwave plasma chemical vapor deposition (MPCVD) reactor. The introduction of TMS in the CH4/H2 plasma leads to a significant enhancement of nucleation density of diamond nuclei, namely from (3.7 ± 0.2) × 107/cm2 without the introduction of TMS to (4.7 ± 0.5) × 1010/cm2 at the TMS flow rate of 4 sccm. On the contrary, further increasing in the TMS flow rate to 8 sccm slightly reduces the nucleation density of diamond nuclei to (2.1 ± 0.3) × 1010/cm2, along with the increase in average size of diamond nuclei. High-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) allow us to study the microstructural and chemical composition evolution of Si/diamond interface. The obtained results suggest that bias-enhanced nucleation of diamond on Si substrate exhibits a direct relationship with the TMS flow rate.

Silicon nitride cover layer prepared by silane-free plasma chemical vapor deposition for high quality surface passivation of silicon solar cells

Passivated emitter and rear contact (PERC) silicon solar cell is one of the most promising high-efficiency solar cells, which uses aluminum oxide (Al2O3) and hydrogenated silicon nitride (SiNx:H) stack as the rear passivation layer. The SiNx:H not only serves as a protective layer but can provide hydrogen atoms that further passivate the dangling bonds on silicon wafer surface. In this study, the SiNx:H cover layers are deposited using high density plasma chemical vapor deposition with a silane-free gas mixture of tetramethylsilane (TMS) and ammonia (NH3). Effects of the TMS gas flow rate on properties of the SiNx:H cover layers and effective minority carrier lifetime of silicon wafers are investigated. The experimental results show that the film density is positively related to the SiN bond proportion. The secondary ion mass spectrometry measurement shows that the dense SiNx:H can make hydrogen atoms move toward wafer surface instead of out-diffusion to the environment. The best SiNx:H film is deposited at a TMS flow rate of 35 sccm. The minority carrier lifetime can be improved from 70 μs for as-cleaned wafer to 373 μs for wafer/Al2O3 and to 1006 μs for wafer/Al2O3/SiNx:H. The surface recombination rate of 23 cm/s is obtained. Therefore, this study demonstrates the dense, silane-free SiNx:H films with high passivation quality for PERC solar cells.

Diamond/β-SiC film as adhesion-enhanced interlayer for top diamond coatings on cemented tungsten carbide substrate

In present work, diamond/β-SiC composite interlayers were deposited on cemented tungsten carbide (WC-6%Co) substrates by microwave plasma enhanced chemical vapor deposition (MPCVD) using H2, CH4 and tetramethylsilane (TMS) gas mixtures. The microstructure, chemical bonding, element distribution and crystalline quality of the composite interlayers were systematically characterized by means of field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), electron probe microanalysis (EPMA), Raman spectroscopy and transmission electron microscropy (TEM). The influences of varying TMS flow rates on the diamond/β-SiC composite interlayers were investigated. Through changing the TMS flow rates in the reaction gas, the volume fraction of β-SiC in the composite interlayers were tunable in the range of 12.0%–68.1%. XPS and EPMA analysis reveal that the composite interlayers are composed of C, Si element with little cobalt distribution. The better crystallinity of the diamond in the composite is characterized based on the Raman spectroscopy, which are helpful to deposit top diamond coatings with high quality. Then, the adhesion of top diamond coatings were estimated using Rockwell C indentation analysis, revealing that the adhesion of top diamond coatings on the WC-6%Co substrates can be improved by the interlayers with the diamond/β-SiC composite structures. Comprehensive TEM interfacial analysis exhibits that the cobalt diffusion is weak from WC-6%Co substrate to the composite interlayer. The homogeneous microcrystalline diamond coatings with the most excellent adhesion can be fabricated on the substrates with the composite interlayer with the β-SiC/diamond ratio of about 45%. The composite structures are appropriate for the application in high-efficiency mechanical tool as a buffer layer for the deposition of the diamond coating.

Growth of large-scale heteroepitaxial 3C-SiC films and nanosheets on silicon substrates by microwave plasma enhanced CVD at higher powers

Abstract The controllable growth of heteroepitaxial cubic SiC (3C-SiC) films and two dimensional (2D) nanosheets arrays has been successfully achieved using a 915 MHz microwave plasma enhanced chemical vapor (MPCVD) deposited technique using tetramethylsilane (TMS) and hydrogen as the resource gases. A comprehensive analysis of the surface morphology of the 3C-SiC films was performed by tuning microwave power, TMS flow rate and gas pressure. With increasing microwave power, the morphology of the SiC crystals evolves from randomly oriented nanocrystals to well-oriented pyramid shaped crystals. The rocking curve results shows that the 3C-SiC film deposited at microwave power of 9 kW and gas pressure of 50 mbar remains epitaxial feature with increasing of TMS gas flow rate. As a result, uniform heteroepitaxial 3C-SiC film was deposited on 4-in. silicon wafer at low deposition temperature (~ 860 °C). The structure of SiC film along the radial direction was measured by X-ray diffraction (XRD) results. X-ray photoelectron spectroscopy (XPS) spectra indicate the chemical information of SiC film surface and the depth profiles, which prove the uniform of elements distribution. Moreover, with increasing gas pressure, the film morphology transforms from the heteroepitaxial SiC film into 2D nanosheets, which is due to the increased ion current.

Effect of tetramethylsilane flow on the deposition and tribological behaviors of silicon doped diamond-like carbon rubbed against poly(oxymethylene)

In this study, silicon doped diamond-like carbon (Si-DLC) was deposited on stainless steel (JIS SUS304) by using surface wave-excited plasma (SWP). The effects of tetramethylsilane (TMS) flow on the composition, topography, mechanical properties and tribological behavior were investigated. Pin-on-disc tribo-meter was used to investigate the tribological behavior of the Si-DLC coating rubbed against poly(oxymethylene) (POM). The results show that the deposition rate, roughness of Si-DLC increased and the hardness of Si-DLC decreased with the increase of TMS flow rate from 2 to 4 sccm; the roughness increase therein led to the increase of ploughing term of friction. The increase of adhesion term was also seen with the increase of TMS flow rate, being attributed to the decrease of hydrogen concentration in the coating. It was considered that more POM transferred onto the Si-DLC deposited at higher TMS flow rate due to larger heat generation by friction.

Synthesis and characterization of Ti–Si–C–N nanocomposite coatings prepared by a filtered vacuum arc method

Ti–Si–C–N nanocomposite coatings were synthesized by a filtered vacuum arc (FVA) technique. A metal organic precursor, tetramethylsilane (TMS), was used as a source for silicon and carbon to deposit the Ti–Si–C–N nanocomposite coating with a Ti cathode source. The chemical and microstructural properties of the as-deposited coatings were systematically investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Nanoindentation and scratch tests were carried out to evaluate the mechanical and adhesion properties of the coatings. From the XPS analysis, it was found that the Si content in the coating increased from 2 to 16at.% as the TMS flow rate was increased from 5 to 20sccm. The TEM analysis clearly demonstrated that the coatings were composed of crystalline TiCN along with amorphous Si3N4 as a secondary phase. From the XRD results, it was found that the crystallite size of TiCN increased with increasing Si content. The microstructure and mechanical properties of the TiSiCN coatings prepared by this method exhibited strong dependencies on the silicon content. A maximum hardness of 49GPa and a coefficient of friction of 0.17 were obtained for the film with a silicon content of 3at.%.

Mechanical properties of silicon-doped diamond-like carbon films prepared by pulse-plasma chemical vapor deposition

Silicon-doped diamond-like carbon (Si-DLC) films were prepared by dc pulse-plasma chemical vapor deposition (CVD), using a mixture of acetylene (C 2H 2) and tetramethylsilane (TMS) as the material gas. The pulse voltage was varied from − 2 to − 5 kV, and the TMS flow ratio (TMS/(C 2H 2 + TMS)) was varied from 0 to 40%. At a pulse voltage of − 2 kV, an increase in TMS flow ratio leads to a decrease in hardness. In contrast, at a pulse voltage of − 5 kV, an increase in TMS flow ratio leads to a slight increase in hardness. The high hydrogen concentration in the films due to an increase in TMS flow ratio promotes the formation of polymeric sp 3 C―H bonds, resulting in the fabrication of soft films at a low pulse voltage of − 2 kV. However, an increase in the effect of ion peening on the growth face results in the formation of hard films at a high pulse voltage of − 5 kV. Then, at a pulse voltage of − 5 kV fabricating hard Si-DLC films, an increase in TMS flow ratio leads to an increase in the silicon content in the films, resulting in a decrease in the friction coefficient. Therefore, it is clarified that Si-DLC films fabricated by dc pulse-plasma CVD under a high pulse voltage and high TMS flow ratio exhibit high hardness and a low friction coefficient. Moreover, to investigate the friction coefficient of Si-DLC films fabricated by dc pulse-plasma CVD, films deposited by dc plasma CVD were also evaluated. To obtain the same low friction coefficient, dc pulse-plasma CVD requires less TMS than dc plasma CVD. Hence, it is also clarified that Si-DLC films can be fabricated at a low cost by dc pulse-plasma CVD.

Thermal stability of Si-doped glow discharge polymer films

The Si-doped glow discharge polymer (Si-GDP) films are deposited by glow discharge polymerization technology at different tetramethylsilane (TMS) flows. The chemical structure, the composition and the thermal stabilities of Si-GDP films are analyzed by the Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermal gravimetric analysis. The results show that the Si content increases from 0 to 16.62%, when the flow of TMS changes from 0 to 0.06 cm3/min. The relative content of SiC, SiH, SiO, SiCH3 increases with TMS flow rate increaseing. As TMS flow increases, the thermal stability of Si-GDP film becomes good.

The mechanical and biocompatibility properties of DLC-Si films prepared by pulsed DC plasma activated chemical vapor deposition

Films of diamond-like carbon containing up to 22 at.% silicon (DLC-Si) were deposited on to silicon substrates by low-frequency pulsed DC plasma activated chemical vapor deposition (PACVD). The influence of silicon doping on deposition rate, composition, bonding structure, hardness, stress, surface roughness and biocompatibility was investigated and correlated with silicon content. A mixture of methane and tetramethylsilane (TMS) was used for the deposition of DLC-Si films at a pressure of 200 Pa. The deposition rate increased with increasing TMS flow. The addition of silicon into the DLC film leads to an increase of sp 3 bonding, as measured by Raman spectroscopy, and also resulted in lower stress and hardness values. The RMS surface roughness of the films was measured by atomic force microscopy and increased from 0.35 nm for DLC to 6.7 nm for DLC-Si (14 at.% Si) due to the surface etching by the H atoms. Biocompatibility tests were performed using MG-63 osteoblast-like cell cultures that were left to grow for 3 days and their proliferations were assessed by scanning electron microscopy. The results indicated a homogeneous and optimal tissue integration for both the DLC and the DLC-Si surfaces. This pulsed PACVD technique has been shown to produce biocompatible DLC and DLC-Si coating with potential for large area applications.

Deposition of nanocomposite thin films by a hybrid cathodic arc and chemical vapour technique

A hybrid technique is described for the synthesis of nanocomposite Ti–Si–N thin films based on the reactive deposition of Ti produced from a cathodic arc source and silicon from a liquid tetramethylsilane (TMS), precursor. The influence of the TMS flow rate on the structure and mechanical properties has been investigated. The film structure was found to comprise TiN crystallites and amorphous Si 3N 4. The X-ray diffraction data showed that with increasing TMS flow there is a decrease in the TiN crystalline size from 33 nm to 4 nm. The hardness of the films was found to be strongly dependent on the Si content and reached a maximum value of 41 GPa at ∼ 5% Si content at a total pressure of nitrogen and TMS of 0.8 Pa. Hardness enhancement was found to arise from the nanostructural change induced due to the addition of an amorphous Si 3N 4 phase into the film. Transmission electron microscopy (TEM) analysis confirmed the structure of the Ti–Si–N composites.

Hydrogen softening and optical transparency in Si-incorporated hydrogenated amorphous carbon films

High-resolution x-ray reflectivity (XRR) and heavy-ion elastic recoil detection were employed to study the role of hydrogen on the softening behavior observed in Si-incorporated hydrogenated amorphous carbon (Si-a-C:H) films synthesized by plasma-enhanced chemical-vapor deposition using tetramethylsilane (TMS) precursor in C2H2∕Ar plasma. An enhancement of the optical band gap and a massive reduction in the density of the films prepared at high TMS flow rate were revealed, respectively, by spectroscopic ellipsometry and XRR analysis with the development of a double critical angle. A hydrogenation process was responsible for a rise in the density of voids and an associated reduction in the connectivity of the carbon network and the release of its residual stress.

Deposition of nanocomposite TiN-Si3N4 thin films by hybrid cathodic arc and chemical vapor process

A hybrid technique is described for the synthesis of nanocomposite TiNSi3N4 thin films based on the reactive deposition of Ti produced from a cathodic arc source and Si from a liquid tetramethylsilane (TMS), precursor. The technique combines both the physical vapour of Ti and chemical vapour of silicon in a nitrogen background pressure in a single system. The influence of the TMS flow rate on the structure and mechanical properties has been investigated. The film structure was found to comprise of TiN crystallites and amorphous Si3N4. The X-ray diffraction data showed that with increasing TMS flow, there is a decrease in the TiN crystalline size from 33 nm to 4 nm. The hardness of the films was found to be strongly dependent on the Si content and reached a maximum value of 41 GPa at ∼5% Si content at a total pressure of nitrogen and TMS of 0.8 Pa. Hardness enhancement was found to arise from the nanostructural change induced due to the addition of an amorphous Si3N4 phase into the film. Transmission electron microscopy (TEM) analysis confirmed the structure of the ncTiN/aSi3N4 composites. Films with 4 at. % or more silicon were found to maintain the hardness after annealing at 500 °C in vacuum.

Effects of Si content in DLC films on their friction and wear properties

Diamondlike carbon (DLC) has been well known as a very hard and very low-friction material. The most critical issue of DLC is to improve its adhesion. To improve the adhesion, some other elements, such as Si, have been included in DLC films. We have studied the effects of Si content on friction and wear properties of DLC films made by our bipolar pulse PBII system. The content of Si was changed by varying the flow rates of tetramethylsilane (TMS) from 0.0 to 3.5 sccm while the flow rate of toluene and the total pressure was kept constant. Friction coefficients (FCs) were measured with a JIS-SUJ2 (AISI 52100) ball of 3-mm diameter. The length of sliding was 2 mm, the speed was 10 mm/s, and the load was 4.9 N for 40-min tests. Without TMS flow, the friction coefficients (FCs) were the largest, 0.35, and the DLC film came off easily. With the increase of TMS flow up to 1.0 sccm, the FC decreased to 0.14, and there was almost no peeling off. For 2.0 sccm, the FC was 0.18, and there was a lot of debris on the DLC surface. Hardness gradually decreased with the increase of TMS flow up to 1.0 sccm, and it decreased drastically for high flow rates or high Si content. Internal stress (compressive) of the films decreased with the increase of TMS flow. Si content in the film corresponded almost linearly to the TMS flow rate. One to two percent of Si doping is very suitable for improving the adhesion of films and reducing internal stress while maintaining the surface hardness of DLC films.

Deposition of diamond/β–SiC Gradient Composite Films by Microwave Plasma-assisted Chemical Vapor Deposition

Mixed-phase diamond/β–SiC composite films with compositional gradient were prepared by microwave plasma-assisted chemical vapor deposition using a gas mixture of hydrogen, methane and tetramethylsilane (TMS). Single-crystalline silicon wafers, pretreated with diamond nanoparticles before deposition, were used as substrates. The film characterization by scanning electron microscopy, electron probe microanalysis, and energy-dispersive x-ray analysis shows that the contents of diamond and silicon carbide in the films vary with TMS flow rate. Diamond/β–SiC composite films with compositional gradients are achievable by varying the TMS flow rate during the film growth process.

The effects of structure, composition, and chemical bonding on the mechanical properties of Si-aC:H thin films

The objective of this study was to correlate mechanical properties with the structure and chemistry of silicon-incorporated amorphous hydrocarbon (Si-aC:H) films deposited by reactive sputtering. Hardness and elastic modulus were measured via microindentation, and intrinsic compressive stress was determined from radius-of-curvature measurements using surface mapping microscopy. Film chemistry was investigated with X-ray photoelectron spectroscopy, electron energy-loss spectroscopy, Raman spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopy. Conventional- and high-resolution transmission electron microscopy revealed that the Si-aC:H phase is amorphous and TiC exists at the Si-aC:H/Ti phase boundary. Mechanical properties such as hardness, modulus, and intrinsic stress decreased with increasing Si and H content in the films, for Si/C⩾0.04. Measurements show that this is most likely due to a decrease in CC sp 3 bonds, accompanied by an increase in CSi and CH bonds. In addition, the Si-aC:H film with Si/C=0.04 is fundamentally different from the other Si-aC:H films with higher Si and H contents. It is concluded that a film with diamond-like carbon characteristics can be deposited using a low tetramethyl silane (TMS) flow rate, such that Si/C=0.04 in the film. However, films deposited with higher TMS flow rates (such that Si/C⩾0.06 in the films) are more characteristic of amorphous hydrogenated silicon carbide.

Mechanistic Study and Characterization of 3C-SiC(100) Grown on Si(100)

Single crystal cubic SiC(100) thin films were grown on Si(100) from thermal cracking of tetramethylsilane (TMS) as a function of growth temperature, reactor pressure, source gas flow rate, and Si/C atomic ratio in a radio frequency-inductive chemical vapor deposition reactor. The orientation of as-grown SiC films mostly followed that of the Si substrate. However, the growth of SiC(111) was detected in the films grown at high TMS flow rates and high Si/C atomic ratios. The thickness of the SiC film was increased with the growth temperature, reactor pressure, TMS flow rate, and Si/C atomic ratio. Voids were formed in the silicon side of the SiC/Si interface, but disappeared when the reactor pressure, TMS flow rate, and Si/C ratio were increased. The formation of voids was attributed to the outdiffusion of Si atoms from the Si substrate. The stresses and strains generated in the grown films were also investigated in terms of the growth conditions. The formation mechanism of voids at the SiC/Si interface was discussed on the basis of the experimental observations. © 2001 The Electrochemical Society. All rights reserved.

Residual stress and texture in poly-SiC films grown by low-pressure organometallic chemical-vapor deposition

We present a study of the stress state of polycrystalline 3C–SiC thin films grown on a-SiO2/Si(100) substrates by low-pressure chemical-vapor deposition using an organometallic precursor, tetramethylsilane (TMS), that contains both Si and C atoms. Substrate curvature and x-ray stress measurements indicate a change from compressive to tensile stress with increasing deposition temperature. Film thickness and TMS flow also influence the total stress of the films. The different microstructure of the films with growth temperature and the presence of impurities are at the origin of the observed differences in the stress. While samples grown below 1100 °C have a columnar structure, are highly oriented along [111], and show compressive stress, those grown at 1130 °C are randomly oriented, with an equiaxial grain shape, and are tensile stressed. The thermal stress is tensile and relatively constant over the temperature range investigated. We speculate the observed intrinsic stress is composed of a tensile and a compressive component. Within the grain-boundary relaxation model we calculate the intrinsic stress variations with temperature due to differences in grain size and density of grain boundaries. The compressive component originates from the presence of oxygen impurities within the film. Peak broadening analysis of the x-ray signal reveals the existence of important microstresses due to low adatom mobility during the deposition process.

Effects of Experimental Parameters on Void Formation in the Growth of 3C‐SiC Thin Film on Si Substrate

The effects of growth parameters have been examined for the epitaxial growth of a void‐free SiC film on a Si substrate. Experiments were performed under various growth conditions by pyrolyzing tetramethylsilane (TMS) in a rapid thermal chemical vapor deposition reactor. Void‐free single crystalline SiC films were grown when the Si substrate was heated after the flow of TMS. The increase of TMS flow rate produced void‐free SiC films, but the crystallinity of the films varied from single crystalline to polycrystalline. The growth of void‐free single crystalline SiC films was observed at substrate temperatures below 1000°C. The outdiffusion of Si atoms from the Si substrate surface and the void formation in the silicon side of the SiC/Si interface were investigated using various experimental techniques. The mechanism of the void formation is briefly discussed in this work.