Silicon Carbonitride Coatings Research Articles

Laser-Plasma Deposition of Silicon Carbonitride Films by the HMDS Vapor Gas Flow Activation after a Laser Beam Focus

A new laser-plasma deposition method has been developed for the plasma chemical deposition of hard silicon carbonitride coatings on stainless steel substrates from the hexamethyldisilazane (HMDS) Si2NH(CH3)6 vapor in a high-speed Ar and Ar + 10 vol.% He gas stream at the HMDS gas flow activation after the laser beam focus. The method allows depositing silicon carbonitride coatings at the rate of 0.4 - 1.2 μm·min-1, i.e. ~2 times higher than that at introducing HMDS in the laser beam focus zone. The properties of the prepared coatings have been studied by the methods of IR and Raman spectroscopy, atomic force microscopy, nanoindentation and X-ray diffraction (XRD) analysis. Studying the film structure with the use of XRD showed that the prepared silicon carbonitride coatings are X-ray amorphous. It has been found that the coating deposition rate and the structure of coatings depend on the process parameters: HMDS flow rate and plasma-generating gas (argon or (Ar + He). The method allows depositing SiCN films at a high speed and a hardness of 20 - 22 GPa.

DEPOSITION OF HARD SILICON CARBONITRIDE COATINGS FROM HEXAMETHYLDISILAZANE (HMDS) AND HMDS+BENZENE VAPORS IN LASER PLASMA

Hard silicon carbonitride coatings are prepared using Ar and Ar (10 vol.% He) laser plasma from hexamethyldisilazane (HMDS) [(CH3)3Si]2NH and HMDS+benzene vapors. The coatings are characterized by infrared (IR), Raman, and X-ray photoelectron spectroscopies, transmission electron microscopy, and atomic force microscopy. The obtained coatings are amorphous and uniform in composition and over the film thickness. The microhardness of coatings synthesized on steel from a HMDS+ benzene mixture increases from 12 GPa to 18 GPa provided that other parameters remain constant.

Synthesis of silicon carbonitride films by activation gas flow in laser power optical pulsating discharge plasma

A new method has been developed for the plasmochemical deposition of hard protective silicon carbonitride coatings from a hexamethyldisilazane (HMDS) Si2NH(CH3)6 vapor and HMDS+ benzene activated by a powerful optic pulse discharge (POPD) in a high-velocity gas flow of argon. The method allows depositing silicon carbonitride coatings with a rate of 0.5−1.2 μm·min−1 that is (1−5)·102 times higher than in conventional CVD processes. It has been found that coating deposition rate and structure of coatings depend on the process parameters: flow rates of HMDS and HMDS+benzene and plasma generating gas (argon). The method allows depositing SiCN coatings containing Si–C, Si–N and Csp3–N bonds with high velocity and microhardness 24 GPa.

Tribological Properties of Magnetron Sputtered Amorphous Silicon Carbide and Silicon Carbonitride Coatings

The tribological properties of magnetron sputtered amorphous silicon carbide (a-SiC) and silicon carbonitride coatings (a-SiCN) with thickness of 2.2 and 3.4 µm were investigated. Samples were additionally annealed at temperature of 700°C or 900°C in air. Progressive load scratch tests were performed on the annealed samples as well as on the as deposited ones. An acoustic emission signal was detected during all tests using the sample holder with embedded sensor of our own design. Results indicate no change in wear resistance of SiCN sample after high temperature exposure up to 900°C, unlike in the tests of SiC coatings. Detection of acoustic emission generated during the scratch test proved to be a significant improvement for the coating evaluation.

Laser plasmochemical synthesis of hard protective SiCN films

A new method of laser plasma deposition had been applied to synthesise the silicon carbonitride (SiCN) coatings on stainless steel substrates and cutting devices using hexamethyldisilazane Si2NH(CH3)6 as a precursor. The precursor vapours were activated by powerful optical pulsating discharge in a high velocity gas stream (Ar). Characterisation of the films has been carried out by complex methods. The deposited coatings are amorphous, uniform in thickness and decorate surfaces of different engineering materials quite well. The nanohardness of SiCN coatings was estimated as 15–24 GPa.

Physical-chemical properties of silicon carbonitride films prepared using laser-plasma deposition from hexamethyldisilazane

A new method of the plasma chemical vapor deposition with the activation of the initial compounds by the plasma of the CO2 laser in the high-speed gas flow has been applied for the synthesis of silicon carbonitride SiCN films on a substrate of stainless steel and instrumental alloys using hexamethyldisilazane vapors. The preparation of the coatings of the laser-plasma deposition in the variants of the chamber and non-chamber deposition has been studied. The properties of the prepared coatings have been studied by the methods of IR and Raman spectroscopy, atomic-force microscopy, and XRD-analysis analysis. The studies of the structure of the films using diffraction synchrotron radiation showed that the prepared silicon carbonitride coatings are X-ray amorphous. The ratio of the Si-C/Si-N bonds in coatings increases with the increase in the substrate temperature. The microhardness of the prepared coatings on stainless steel substrates is 15–25 GPa.

Atmospheric-Pressure Plasma-Enhanced Chemical Vapor Deposition of a-SiCN:H Films: Role of Precursors on the Film Growth and Properties

Atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) using Surfx Atomflow(TM) 250D APPJ was utilized to synthesize amorphous silicon carbonitride coatings using tetramethyldisilizane (TMDZ) and hexamethyldisilizane (HMDZ) as the single source precursors. The effect of precursor chemistry and substrate temperature (T(s)) on the properties of a-SiCN:H films were evaluated, while nitrogen was used as the reactive gas. Surface morphology of the films was evaluated using atomic force microscopy (AFM); chemical properties were determined using Fourier transform infrared spectroscopy (FTIR); thickness and optical properties were determined using spectroscopic ellipsometry and mechanical properties were determined using nanoindentation. In general, films deposited at substrate temperature (T(s)) < 200 °C contained organic moieties, while the films deposited at T(s) > 200 °C depicted strong Si-N and Si-CN absorption. Refractive indices (n) of the thin films showed values between 1.5 and 2.0, depending on the deposition parameters. Mechanical properties of the films determined using nanoindentation revealed that these films have hardness between 0.5 GPa and 15 GPa, depending on the T(s) value. AFM evaluation of the films showed high roughness (R(a)) values of 2-3 nm for the films grown at low T(s) (<250 °C) while the films grown at T(s) ≥ 300 °C exhibited atomically smooth surface with R(a) of ~0.5 nm. Based on the gas-phase (plasma) chemistry, precursor chemistry and the other experimental observations, a possible growth model that prevails in the AP-PECVD of a-SiCN:H thin films is proposed.

N-bromohexamethyldisilazane: Investigation of properties and thermodynamic simulation of precipitation of thin-layer structures from the vapor phase

N-Bromohexamethyldisilazane has been characterized using an elemental analysis and IR, UV, 1H NMR, 13C NMR, and 29Si NMR spectroscopy. The spectral characteristics of the compound have been determined and the saturated vapor pressure has been measured. The thermodynamic simulation of the chemical vapor deposition (CVD) of silicon carbonitride films in the Si-C-N-Br-H system has been performed at low pressures (13.30 and 1.33 Pa) over a wide temperature range (from 400 to 1200 K) with the use of initial gas mixtures of N-bromohexamethyldisilazane with hydrogen and ammonia. The possibility of preparing films of different compositions has been demonstrated and the optimum conditions for deposition of silicon carbonitride coatings of the general composition SiCxNy have been established.

A Novel Organosilicon Source for Low Temperature Plasma Deposition of Silicon Nitride‐like Thin Films

AbstractSummary: This paper deals with the deposition of silicon nitride‐like films at low temperatures using radio frequency inductively coupled plasmas fed with bis(dimethylamino)dimethylsilane (BDMADMS) and argon (Ar). The effect of input power and BDMADMS‐to‐Ar ratio on the chemical composition of the deposited films has been investigated by means of Fourier transform infrared absorption spectroscopy (FT‐IRAS) and X‐ray photoelectron spectroscopy (XPS) analysis. The results indicate that at high input power and low monomer‐to‐Ar ratio, low carbon and high nitrogen content films, stable and with a refractive index of 1.87, can be obtained. Under the same experimental conditions, high carbon content silicon carbonitride coatings have been deposited from hexamethyldisilazane and Ar fed discharges.Normalized FT‐IR absorption spectra of films deposited in plasmas fed with BDMADMS‐Ar (ratio = 0.1) in comparison with the spectrum of a thermal SiNx film (HT‐SiN).magnified imageNormalized FT‐IR absorption spectra of films deposited in plasmas fed with BDMADMS‐Ar (ratio = 0.1) in comparison with the spectrum of a thermal SiNx film (HT‐SiN).

Hard amorphous silicon carbonitride coatings produced by plasma enhanced chemical vapour deposition

Hard amorphous silicon carbonitride coatings for wear resistance have been produced by d.c. plasma‐enhanced chemical vapour deposition on pure iron at 573 K. Compared with most plasma assisted processes work was conducted under a relatively high pressure of 130 Pa. The advantages of this technique are an amorphous film structure, high deposition rates (up to 2 μm/min), high hardness and simple equipment. Hexamethyldisilazan (HMDSN) was used as precursor and argon, hydrogen, nitrogen and ammonia as process gases. The dependence of the coatings on the process parameters (process gas and d.c. power) was investigated. The characterization of the samples was carried out mainly by Fourier transform infrared spectrometry (FTIR), electron probe microanalysis (EPMA) and hardness measurement. Samples show clearly the infrared spectra absorption bands characteristic of SiC and Si3N4, with traces of hydrogen bonding. The material structure shows a strong dependence on the process gas and the d.c. power. However, for argon and hydrogen were deposited carbon‐rich SiC films with low nitrogen content. Nitridic films with low carbon content were deposited using nitrogen and especially ammonia. The hardness of the produced coatings was about 10 ‐ 55 GPa.

Laser-Induced Chemical Vapour Deposition of Silicon Carbonitride

Laser-induced Chemical Vapour Deposition of silicon carbonitride coatings and powders has been investigated using hexamethyldisilazane (HMDS) and ammonia as reactants. An industrial CW CO 2 -laser in parallel configuration has been used to heat up the reactant gases. HMDS dissociates in the laser beam and reactive radicals are formed which increase rapidly in molecular weight by an addition mechanism. Dense polymer-like silicon carbonitride thin films and nanosized powders are formed depending on process conditions. Powder particles are deposited on a substrate by means of a thermal gradient. The primary particle size is about 30 nm. The particles are agglomerated. Depositions are characterized with spectroscopic and chemical analysis and correlated to some important laser process parameters. The powder deposit and the thin film consist of Si-N, Si-C and Si-O bonds according to FTIR-spectroscopy and X-ray Photo-Electron Spectroscopy. A residual amount of hydrogen is present. The material is amorphous (XRD) and has a polymer-like structure. The overall composition varies around Si 0.4 C 0.1 N 0.3 O 0.2 . The nitrogen content increases significantly by adding ammonia to the reactant gas flow. The high amount of oxygen is caused by hydrolysis and is a result of being exposed to air.

SiC-Si 3N 4 composite coatings produced by plasma-enhanced chemical vapour deposition

Silicon carbonitride coatings have been produced by plasma-enhanced chemical vapour deposition (CVD) on AISI 440C steel in a hot-wall reactor at 250 °C from a mixture of SiH 4, N 2-NH 3 andC 2H 4, and analysed by electron probe microanalysis and Rutherford backscattering spectroscopy-elastic recoil detection. Coatings with different ratios of silicon carbide to silicon sub- and superstoichiometries have been deposited. Stoichiometric coatings show a maximum in their mechanical properties. Depending on the SiC-to-Si 3N 4 ratio, the Knoop hardness values vary between 1500 and 2800 HK 0.025. Internal stress is low at a level of 100–300 MPa. The pinhole density is less than 2 cm -2. The fracture toughness as determined from indention tests is 4 MPa m 1/2 Linear polarization testing results show excellent protection of the substrate material against chemically aggressive media as compared with conventional CVD.