Silicon Carbonitride Films Research Articles

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.

Low temperature plasma enhanced chemical vapor deposition of thin films combining mechanical stiffness, electrical insulation, and homogeneity in microcavities

The deposition of hydrogenated amorphous carbon (a-C:H) as well as hydrogenated amorphous silicon carbonitride (SiCN:H) films was investigated in view of a simultaneous realization of a minimum Young’s modulus (>70 GPa), a high electrical insulation (≥1 MV/cm), a low permittivity and the uniform coverage of microcavities with submillimeter dimensions. For the a-C:H deposition the precursors methane (CH4) and acetylene (C2H2) were used, while SiCN:H films were deposited from mixtures of trimethylsilane [SiH(CH3)3] with nitrogen and argon. To realize the deposition of micrometer thick films with the aforementioned complex requirements at substrate temperatures ≤200 °C, several plasma enhanced chemical vapor deposition methods were investigated: the capacitively coupled rf discharge and the microwave electron cyclotron resonance (ECR) plasma, combined with two types of pulsed substrate bias. SiCN:H films deposited at about 1 Pa from ECR plasmas with pulsed high-voltage bias best met the requirements. Pulsed biasing with pulse periods of about 1 μs and amplitudes of about −2 kV was found to be most advantageous for the conformal low temperature coating of the microtrenches, thereby ensuring the required mechanical and insulating film properties.

Synthesis and characterization of silicon carbonitride films by plasma enhanced chemical vapor deposition (PECVD) using bis(dimethylamino)dimethylsilane (BDMADMS), as membrane for a small molecule gas separation

Silicon carbonitride thin films have been deposited by plasma enhanced chemical vapor deposition (PECVD) from bis(dimethylamino)dimethylsilane (BDMADMS) as a function of X = (BDMADMS/(BDMADMS + NH 3)) between 0.1 and 1, and plasma power P (W) between 100 and 400 W. The microstructure of obtained materials has been studied by SEM, FTIR, EDS, ellipsometrie, and contact angle of water measurements. The structure of the materials is strongly depended on plasma parameters; we can pass from a material rich in carbon to a material rich in nitrogen. Single gas permeation tests have been carried out and we have obtained a helium permeance of about 10 −7 mol m −2 s −1 Pa −1 and ideal selectivity of helium over nitrogen of about 20.

Plasma-chemical synthesis of silicon carbonitride films from trimethyl(diethylamino)silane

Silicon carbonitride films of different compositions have been synthesized by plasma-enhanced chemical vapor deposition with the use of trimethyl(diethylamino)silane as the initial compound. The conditions used for the deposition of the films have been chosen from the thermodynamic modeling. The properties of the films prepared have been investigated using ellipsometry, scanning electron microscopy, X-ray photoelectron spectroscopy, IR spectroscopy, and synchrotron X-ray powder diffraction. It has been established that the synthesis temperature substantially affects the kinetics of growth and physicochemical properties of silicon carbonitride layers in the range of synthesis conditions under investigation. The films prepared consist of nanoparticles whose size increases with increasing synthesis temperature. The refractive index of the films increases from 1.6 to 2.8 with an increase in the temperature.

Correlation of structure and hardness of rf magnetron sputtered silicon carbonitride films

Ternary nanocomposite silicon carbonitride (SiCN) ceramic coatings have shown potential for wear resistance, oxidation resistance, hardness, tunable band gap, and chemical inertness applications. A systematic investigation on the deposition of SiCN nanocomposite coatings by sputtering under varying deposition conditions such as chamber pressure, substrate temperature by structural, nanoindentation, and microstructural studies of optimized condition has been presented. Significant role of different deposition parameter on the mechanical and structural properties were observed. The structural characterizations of the coatings were carried out using Fourier transformed infra red (FTIR), transmission electron microscopy, Raman spectroscopy, and field emission scanning electron microscope. An increase in argon-nitrogen pressure in the range of 1–5 Pa led to lowering of particle size and surface smoothening and growth of hard phases of β-C3N4 and β-Si3N4. An increase in substrate temperature from room temperature to 500 °C led to nucleation and growth of hard phases of β-C3N4 and Si3N4 in the amorphous SiCN matrix. The nanoindentation studies showed the variation in hardness and Young’s modulus from 8 to 22 GPa and from 100 to 240 GPa, respectively, dependent on the deposition conditions. The FTIR studies confirmed the presence of CN, SiN, SiSi, SiO, and SiC in different films.

Characterization of some trimethyl(organylamino)silanes—precursors for preparation of silicon carbonitride films

A series of aminosilanes has been synthesized by the reaction of carboxylic acid di(organyl)amides with trimethyliodsilane. A purification method providing an increase in the yield of end products to 82% has been developed. The identity of the products has been confirmed using an elemental analysis and IR, UV, and 1H NMR spectroscopy. The spectral characteristics of the synthesized aminosilanes have been determined. The temperature dependences of the saturated vapor pressure have been established, and the thermodynamic characteristics of the vaporization processes have been calculated. It has been demonstrated that the aminosilanes Me3SiNEt2, Me3SiNHAll, and Me3SiNHPh are heat resistant in the temperature range 296–452 K and have a vapor pressure sufficient for their use in the processes of chemical vapor deposition of a substance, so that they can be recommended as precursors for synthesis of silicon carbonitride films.

Features of determination of thickness of dielectric films obtained in searching experiments

The approach to determination of the thickness and the refractive indices of dielectric films obtained in searching experiments is discussed. Experiments of this kind often exhibit unpredictable values of thickness and refractive indices of films. Nondestructive noncontact methods of spectrophotometry and ellipsometry not involving preliminary preparation of samples are applied. The approach to determination of the thickness and the refractive indices of films is illustrated by means of samples of silicon carbonitride films obtained on silicon substrates by plasma-chemical decomposition of gas-phase trimethyl(phenylamino)silane.

Electro-optical modulating multistack device based on the CMOS-compatible technology of amorphous silicon

In this paper we report results on a field-effect induced light modulation at λ = 1.55 µm in a high-index-contrast waveguide based on a multisilicon-on-insulator (MSOI) platform. The device is realized with the hydrogenated amorphous silicon (α-Si:H) technology and it is suitable for monolithic integration in a CMOS Integrated Circuit. The device exploits the free carrier optical absorption electrically induced in the semiconductor core waveguide. The dynamic behaviour of the device was experimentally and theoretically analyzed in presence of a visible illumination showing a link between the photogeneration and the free carriers provided by doped α-Si:H layers. The core waveguide contains several thin dielectric films of amorphous silicon carbonitride (α-SiCN) embedded along its thickness highly enhancing the absorbing action of the modulator held in the on-state.

Electrooptical Modulating Device Based on a CMOS-Compatible <formula formulatype="inline"> <tex Notation="TeX">${\bm \alpha}$</tex> </formula>-Si:H/<formula formulatype="inline"> <tex Notation="TeX">${\bm \alpha}$</tex> </formula>-SiCN Multistack Waveguide

In this paper, we report results on a field-effect-induced light modulation at λ = 1.55 μm in a high-index-contrast waveguide based on a multisilicon-on-insulator platform. The device is realized with the hydrogenated amorphous silicon (α-Si:H) technology, and it is suitable for monolithic integration in a CMOS IC. The device exploits the free-carrier optical absorption electrically induced in the semiconductor core waveguide. The amorphous silicon waveguiding layer contains several thin dielectric films of amorphous silicon carbonitride (α-SiCN) embedded along its thickness, thus highly enhancing the absorbing action of the modulator held in the on state.

Influence of radiofrequency power on compositional, structural and optical properties of amorphous silicon carbonitride films

The silicon carbonitride (SiCN) films were deposited on n-type Si (1 0 0) and glass substrates by the radiofrequency (RF) reactive magnetron sputtering of polycrystalline silicon target under mixed reactive gases of acetylene and nitrogen. The films have been characterized by energy dispersive spectrometer (EDS), atomic force microscope (AFM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible spectrophotometer (UVS). The influence of RF power on the compositional, morphological, structural and optical properties of the SiCN films was investigated. The SiCN films deposited at room temperature are amorphous, and the C, Si and O compositions except N in the films are sensitive to the RF power. The surface roughness and optical band gap decrease as the RF power increases. The main bonds in the SiCN films are C–N, N–H n , C–H n , C–C, C N, Si–H and Si–C, and the intensities of the C N, Si–H and C–H n bonds increase with increment of the RF power. The mechanisms of the influence of RF power on the characteristics of the films are discussed in detail.

Structural and mechanical properties of amorphous silicon carbonitride films prepared by vapor-transport chemical vapor deposition

The deposition of amorphous silicon carbonitride (a-SiCN:H) films has been successfully achieved through an in-house developed vapor-transport chemical vapor deposition (VT-CVD) technique in a nitrogenated atmosphere. Polydimethylsilane (PDMS) was used as a single-source precursor for both silicon and carbon, while NH 3 was mixed with argon to ensure the in-situ nitrogenation of the films. The chemical bonding and the atomic composition of the a-SiCN:H films were systematically investigated, as a function of their N content, by means of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). AFM was used to obtain 2-D and 3-D views of the films. The mechanical properties [(hardness ( H) and Young's modulus ( E)] of the freshly prepared films were investigated by the nanoindentation technique. It is shown that by controlling the NH 3/Ar gas flow ratio in the reactor, a-SiCN:H films with various N contents [(0–27) at.% range] are achieved. On the microstructural level, the increase incorporation of N in the a-SiCN:H films is found not only to lead to C atom substitution by N atoms in the local Si–C–N environment but also to an enhanced incorporation of hydrogen bonded to both Si and N. Furthermore, the increase incorporation of N in the a-SiCN:H films resulted in an increase of the average R rms surface roughness from 4 to 12 nm. Moreover, the films became porous with pore size and density increase as a result of increasing N at.%. Ultimately, both H and E of the a-SiCN:H films were found to be sensitive to their N content, as they decrease (from ~ 17 GPa and 160 GPa to ~ 13 GPa and 136 GPa, respectively) when the N content is increased from 0 to 27 at.%. The formation of Si–N, Si–H, and N–H bonds at the detriment of the more stiff Si–C bonds is thought to account for the observed lowering of the mechanical properties of the a-SiCN:H films as their N content increased.

Use of hexamethylcyclotrisilazane for preparation of transparent films of complex compositions

This paper reports on the results of the thermodynamic modeling of chemical vapor deposition of SiC x N y silicon carbonitride films with the use of the volatile organosilicon compound hexamethylcyclotrisilazane (HMCTS) over a wide temperature range 300–1300 K at low pressures of 10−2−10 Torr. It is demonstrated that there are ranges of conditions under which the gas phase is in equilibrium with a mixture of solid phases SiC + Si3N4 + C with the total composition represented in the form of the ternary compound SiC x N y . Transparent silicon carbonitride films of different compositions are experimentally obtained under conditions in the above range through plasma-enhanced chemical vapor deposition at a pressure of 5 × 10−2 Torr and temperatures of 373–1023 K with the use of the initial gaseous mixture of hexamethylcyclotrisilazane and helium. The chemical and phase compositions of the films are determined and their properties are investigated using ellipsometry, IR and Raman spectroscopy, spectrophotometry, energy-dispersive spectroscopy, and synchrotron X-ray powder diffraction. It is shown that the films synthesized at low temperatures of 373–573 K contain a considerable amount of hydrogen. The results obtained ftom atomic-force and scanning electron microscopy indicate that the films involve nanograins.

Plasma-chemical deposition of SiCN films from volatile N-bromhexamethyldisilazane

Process of silicon-carbonitride (SiCN) film production from a new volatile organosilicon, N-bromhexamethyldisilazane, is developed. The use of this chemical comprising the relatively week N-Br bond makes it possible to increase the film growth velocity in the plasma-chemical process with remote plasma in comparison with the processed in which hexamethyldisilazane and hexamethylcyclotrisilazane are used. The chemical composition of the films is determined using a complex of spectroscopic methods. It is found that inorganic SiCN films containing Si-N, Si-C, and C-N bonds are deposited at temperatures 570–870 K. The C-N bonds are formed already at a temperature of about 470 K. It is shown that the use of this volatile organosilicon material makes it possible to synthesize silicon carbonitrides with various ratios of the Si-C, Si-C, and C-N bonds. This enriches the possibilities of producing films and coatings with various functional parameters. The nanohardness of 100-nm films prepared at T > 770 K is 17 GPa.

Study of structural and electronic environments of hydrogenated amorphous silicon carbonitride (a-SiCN:H) films deposited by hot wire chemical vapor deposition

Hydrogenated amorphous silicon carbon nitride (a-SiCN:H) thin films were deposited by hot wire chemical vapor deposition (HWCVD) using SiH 4, CH 4, NH 3 and H 2 as precursors. The effects of the H 2 dilution on structural and chemical bonding of a-SiCN:H has been investigated by Raman and X-ray photoelectron spectroscopy (XPS). Increasing the H 2 flow rate in the precursor gas more carbon is introduced into the a-SiCN:H network resulting in decrease of silicon content in the film from 41 at.% to 28.8 at.% and sp 2 carbon cluster increases when H 2 flow rate is increased from 0 to 20 sccm.

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.

Very low surface recombination velocity of crystalline silicon passivated by phosphorus‐doped a‐SicxNy:H(n) alloys

AbstractHydrogenated and phosphorus‐doped amorphous silicon carbonitride films (a‐SiCxNy:H(n)) were deposited by plasma‐enhanced chemical vapor deposition (PECVD) on crystalline silicon surface in order to explore surface passivation properties. Very silicon‐rich films yielded effective surface recombination velocities at 1 sun‐illumination as low as 3 cm s−1 and 2 cm s−1 on 1 Ω cm p‐ and n‐type crystalline silicon substrates, respectively. In order to use them as anti‐reflection coating, we increased alternatively either the carbon or nitrogen content of these films. Also, a combination of passivation and antireflective films was analyzed. Finally, we explored the passivation stability under high‐temperature steps. Copyright © 2007 John Wiley & Sons, Ltd.

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.

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).

Thin silicon carbonitride films are perspective low- k materials

The multifunctional amorphous and nanocrystalline silicon carbonitride thin films were synthesized by RPECVD using the gas mixture of hexamethyldisilazane (HMDS) with ammonia and helium within temperature range 600–1073 K. IR spectroscopy, Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), ellipsometry, X-ray diffraction using synchrotron radiation (XRD-SR), scanning electron microscopy (SEM), high-resolution electron microscopy (HREM), selected area electron diffraction (SAED), atomic force microscopy (AFM), measurements of hardness by nanoindenter, electrophysical and spectrophotometry measurements were applied to study their physicochemical properties. The presence of chemical bonding among Si, N, and C elements in SiC x N y films was established. According to data of XRD-SR, HREM, and SAED, the formation of the solid substitution solution occurs, with lattice parameters close to those of the standard phase α-Si 3N 4 in which a part of silicon atoms is substituted by carbon atoms. The analysis of electrophysical, optical, and mechanical properties of these films indicates the possibility for applications as low- k materials with mechanical characteristics and transparent layers in wide region of spectra (400–2200 cm −1).

Low- k dielectrics on base of silicon carbon nitride films

Thin silicon carbonitride films were synthesized by PECVD using siliconorganic compound as single-source precursor within a temperature range of 373–623 K. IR and Raman spectroscopy, AES, XPS, ellipsometry, XRD using the synchrotron radiation, EDS, SEM, AFM, measurements of electrophysical, mechanical characteristics and optical properties were applied to study their physicochemical and functional properties. It was shown that low temperature films are low- k dielectrics with the following characteristics: a dielectric constant of 3.0–7.0, specific resistance, ρ = 10 13–10 16 Om × cm, E dielectric breakdown ∼ 1 MV/cm, surface state density N ss ∼ 2.4·10 11 cm − 2 ·eV − 1 and fixed charge density of about 1.6 × 10 11 cm − 2 . The bandgap of the films changes from 5.35 up to ∼ 3.30 eV. Obtained films are very flat and smooth, root mean square roughness R ms equals to ∼ 0.5–1.0 nm. Microhardness of these films changes from 1.9 up to 2.4 GPa, and Young's modulus changes from 12.2 up to 15.9 GPa.