Study of growth rate and failure mode of chemically vapour deposited TiN,TiCxNy and TiC on cemented tungsten carbide

The effects of deposition temperature and mole ratio of CH₄ to TiCl₄ on the growth rate of titanium compound coatings were investigated. Activation energies of TiN, TiC _x N _y and TiC deposition reactions of 4.8×10⁴, 1.9×10⁵ and 2.8×10⁵ J mol^–1, respectively, were obtained experimentally. The carbon content of TiC _x N _y deposit was increased as the CH₄ flow rate and deposition temperature increased. It was found that TiC _x N _y grain size was finer than TiC and TiN.The cutting temperatures of TiN-coated and TiC-coated tools were 10% (TiN) and 20% (TiC) lower than that of uncoated tools. Feed force and reaction force of coated tools were 30% and 18% less than those of uncoated tools, respectively. The dominant failure mode of coated tools was due to the microchipping of the cutting edge.     

Chemical vapour deposition of corrosion-resistant TiN film to the inner walls of long steel tubes

A uniform TiN film was coated on to the inner walls of long steel tubes by moving a chemical vapour deposition furnace along the tubes. The moving direction of the furnace from outlet side to inlet side gave a more homogeneous coating than the reverse moving direction. The TiN-coated steel tube (inside diameter 10 mm) was obtained under the following conditions; peak deposition temperature 1050° C, total flow rate of reactant gas (TiCl₄ + N₂ + H₂) 6.0 ml sec^–1, moving velocity of the furnace 2.8 mm min^–1. The inner wall of the coated tube showed high corrosion resistance for dipping in 6N HCI aqueous solution for 17 h.     

Improvement of the properties and electrical performance on TiCl4-based TiN film using sequential flow chemical vapor deposition process

Sequential flow chemical vapor deposition (SFCVD), utilizing TiCl₄/NH₃ as reactants and immediate NH₃ treatment after film deposition, is applied to produce TiN barrier films in the contact process. Secondary ion mass spectroscopy results indicate that the SFCVD TiN film can effectively block the diffusion of WF₆ into the underlying Ti layer during W deposition. NH₃ treatment immediately after film deposition causes SFCVD TiN films to be less contaminated with carbon than TiN films that are formed by metallic organic compounds chemical vapor deposition (MOCVD) and to contain less chlorine residue than conventional TiCl₄/NH₃ CVD TiN layers even at a low reaction temperature. According to the resistance measurement of Kelvin contacts, the SFCVD process yields a lower resistance and a more uniform distribution than the MOCVD or CVD process. Transmission electron microscopic observations demonstrate that WF₆ can diffuse through the MOCVD TiN to react with the underlying Ti layer, causing a rupture at the Ti/TiN interface and poor W adhesion. The SFCVD TiN can serve as a sufficient diffusion barrier against WF₆ penetration during W CVD deposition.     

Preparation of cobalt oxide films by plasma-enhanced metalorganic chemical vapour deposition

Co oxide films were prepared on glass substrates at 150–400°C by plasma-enhanced metalorganic chemical vapour deposition using cobalt (II) acetylacetonate as a source material. NaCl-type CoO films were formed at low O₂ flow rate of 7cm³ min^–1 and at a substrate temperature of 150–400°C. The CoO films possessed (100) orientation, independent of substrate temperature. Deposition rates of the CoO films were 40–47 nm min^–1. The CoO film deposited at 400 °C was composed of closely packed columnar grains and average diameter size at film surface was 60 nm. At high O₂ flow rate of 20–50 cm³ min^–1, high crystalline spinel-type Co₃O₄ films were formed at a substrate temperature of 150–400°C. The Co₃O₄ film deposited at 400°C possessed (100) preferred orientation and the film deposited at 150°C possessed (111) preferred orientation. Deposition rates of the Co₃O₄ films were 20–41 nm min^–1. Both Co₃O₄ films with (100) and (111) orientation had columnar structure. The shape and average size of the columnar grains at the film surface were different; a square shape and 35 nm for (100)-oriented Co₃O₄ film and a hexagonal shape and 60 nm for (111)-oriented film, respectively.     

Fabrication of low-resistivity and gold-colored TiN films by halide chemical vapor deposition with a low [NH3]/[TiCl4] flow ratio

This work describes the preparation of titanium nitride (TiN) films on Si (111) substrates by atmospheric pressure halide chemical vapor deposition (AP-HCVD). Various TiN films were obtained by exploiting TiCl₄ + NH₃ gas chemistry with flow ratios [NH₃]/[TiCl₄] from 0.2 to 1.4, and deposition temperatures (T_d) from 600 to 900 °C. When T_d = 800 °C gold-colored films with electrical resistivities of under 100 μΩ cm were formed at almost all of the investigated [NH₃]/[TiCl₄] flow ratios. In particular, a lowest resistivity of about 23.7 μΩ cm, which is quite close to that of bulk TiN, was achieved using an [NH₃]/[TiCl₄] flow ratio of 0.3. Atomic force microscopy indicated that the root mean square surface roughness of that film was only about 5.1 nm. Under the same [NH₃]/[TiCl₄] flow ratio as above, X-ray diffraction analyses revealed the presence of a cubic TiN phase with a preferred orientation of (200) for T_d ≤ 800 °C, while additional (111) and (220) orientations emerged when the film was deposited at 900 °C. In conclusion, a low resistivity (< 100 μΩ cm) TiN film can be formed by AP-HCVD with very low [NH₃]/[TiCl₄] flow ratios 0.3-1.4.     

The effects of pre-implantation of steel substrates on the structural properties of TiN coatings

We have studied the effects of nitrogen pre-implantation of AISI C1045 steel substrates on the microstructure and microhardness of deposited TiN coatings. The substrates were implanted at 40 keV, to the fluences from 5 × 10¹⁶ to 5 × 10¹⁷ ions/cm², which was followed by deposition of 1.3-μm thick TiN coatings by reactive sputtering. Structural characterization of the samples was performed by standard and grazing incidence X-ray diffraction analysis, Rutherford backscattering spectroscopy and transmission electron microscopy. Microhardness was measured by the Vicker’s method. Nitrogen implantation up to 2 × 10¹⁷ ions/cm² induces the formation of Fe₂N phase in the near surface region of the substrates, which becomes more pronounced for higher fluences. Microstructure of the deposited TiN coatings shows a strong dependence on ion beam pre-treatment of the substrates. The layers grown on non-implanted substrates have a (200) TiN preferential orientation, and those grown on implanted substrates have (111) TiN preferential orientation. The change in preferred orientation of the layers is assigned to a developed surface topography of the substrates induced by ion implantation, and possible effects of distorted and altered crystalline structure at the surface. Ion implantation and deposition of TiN coatings induce an increase of microhardness of this low performance steel for more than eight times.     

Influence of different process parameters on physical properties of fluorine dopes indium oxide thin films

Fluorine-doped indium oxide films were prepared by the spray pyrolysis technique. The physical properties of these films were investigated with respect to various process parameters, namely variation of dopant concentration (in the solution), deposition temperature (T _s), carrier gas (air) flow rate and the thickness of the film. The best films had a Hall mobility of the order of 28 cm²V^–1 s^–1 and a carrier density of 2.7 × 10²⁰ cm^–3. These films were deposited at T _s=425 °C at an air flow rate of 71 min^–1 for an atomic ratio of fluorine to indium of 72%. The electrical resistivity of these films was of the order of 10^–4 cm and the average transmission in the visible range was found to be 80–90%. The films were polycrystalline, n-type semiconductors with [400] as a preferred orientation. The preferred orientation changes from [400] to [222] depending upon the process parameters.     

TiCxNy and TiCx-TiN films obtained by CVD in an ultrasonic field

TiC _x N _y mono- and TiC_x-TiN double-layer films with a thickness of 30 to 100 m were prepared on a carbon steel (C: 0.6 to 0.7%) substrate by CVD in an ultrasonic field (ultrasound frequency: 19kHz; power: 10 to 20Wcm^–2). The moderate deposition conditions for obtaining an adherent and thick film of TiC _x N _y were: substrate temperature: 1050° C; H₂, N₂, TiCl₄ and CH₄ flow rates: 6.2, 4.0, 0.9 and 0.26 to 2.0 ml sec^–1, respectively. The growth rate, grain size and degree of 2 2 0 preferred orientation were found to decrease with increase in CH₄ concentration. TiC _x N _y film on carbon steel had a Vickers microhardness of 1800 to 2600 and an adhesion strength to the substrate of more than 120 kg cm^–2. A TiC _x -TiN (x0.5) double-layer film was obtained at 1050° C by a controlled alternative deposition of TiC _x or TiN. Quasiepitaxial growth of crystallites in the double layers was found to prevail in both coatings of TiC _x (220)/TiN (220)/steel and TiN (200)/TiC_x (200)/steel.     

Plasma-enhanced chemical vapour deposition of AlN coatings on graphite substrates

Graphite substrates have been covered with aluminium nitride (AlN) layers prepared by plasma-enhanced chemical vapour deposition from AlBr₃-N₂-H₂-Ar gas mixtures. The glow discharge (frequency, 13.56 MHz; power, 50–500 W) was generated by an r.f. induction coil. The graphite substrate mounted on a grounded graphite susceptor was inductively heated up to a temperature in the range 200–800 °C. The mass of the deposit per square centimetre was determined as a function of reaction time, total gas pressure, substrate temperature, r.f. power, gas flow velocity and AlBr₃ concentration. The morphology of the AlN layers was examined by scanning electron microscopy. Fine-grained polycrystalline AlN films were grown at 700 °C under a total pressure below 10 Torr. Translucent polycrystalline AlN films having a 〈001〉 preferred orientation were deposited at a total pressure in the range 10–40 Torr.     

Structures and mechanical properties of TiN/SiNx multilayer films deposited by magnetron sputtering at different N2/Ar gas flow ratios

Polycrystalline TiN/SiN_x multilayer films are deposited using reactive magnetron sputtering Ti and Si, respectively, discharging a mixture of N₂ and Ar gas with different N₂/Ar gas flow ratios, and their structures and mechanical properties are characterized by X-ray reflectivity (XRR), X-ray diffraction (XRD) and nanoindentation. It is found that when the N₂/Ar gas flow ratio is low, the interface between TiN and SiN_x layer for the obtained TiN/SiN_x film is sharp and the preferred orientation for TiN layer is TiN (200). In contrast, when the N₂/Ar gas flow ratio is high, the interface becomes rough and the preferred orientation for TiN layer changes to TiN (111). Nanoindentation experiments exhibit that the TiN/SiN_x film with a TiN (111) preferred orientation is harder than that with a TiN (200) preferred orientation, and all films have nano-scale fracture characteristics.     

Effects of the reaction parameters on the deposition characteristics in ZrO2 CVD

Zirconium dioxide (ZrO₂) films have been deposited on to silicon wafers by the chemical vapour deposition (CVD) technique involving the application of gas mixtures of ZrCl₄, CO₂, and H₂. The relationships between the deposition rate and various reaction parameters, such as the gas flow rate, the deposition temperature, and the composition of reactant gases, were studied. The film was identified as nearly stoichiometric monoclinic ZrO₂ by using X-ray photoelectron spectroscopy, infrared transmission, and X-ray diffraction. Zirconium tetrachloride (ZrCl₄) is the only species acting as zirconium donor which results from thermodynamic calculations in the present system. The CVD of ZrO₂ is a thermally activated process and the activation energy is about 80 kJ mol^–1 at the surface chemical reaction controlled region. The deposition mechanism, initially a kinetic process controlled by diffusive mass transfer, becomes a kinetic process governed by the surface chemical reactions with increasing total flow rate above 700°C. The dependence of the deposition rate on the reactant gas composition is mainly affected by the relative contents of the zirconium donor and the oxygen donor. At ZrCl₄ mole fractions lower than 2.0 × 10^–3, the deposition rate increases with the ZrCl₄ mole fraction; however, at ZrCl₄ mole fractions higher than that the deposition rate is mainly influenced by the H₂O-forming reaction between CO₂ and H₂.     

Shock tube study of the formation of TiN molecules and particles

The formation of both TiN molecules and particles in TiCl₄/NH₃/H₂ systems was studied behind reflected shock waves at temperatures between 1400 and 2500 K and pressures between land 2.3 bar by applying laser absorption spectroscopy. Only in a small temperature and concentration range, molecular absorption of TiN in the A² Π ← X² Σ system was observed. In most experiments, light extinction by TiN particles was found, showing an induction time that only depends on temperature and TiCl₄ concentration but not on NH₃, H₂ or on total pressure.     

Structure and properties of refractory compounds deposited by electron beam evaporation

This work reports on the structure and properties of the refractory compounds TiC, ZrC, TiB₂, ZrB₂, TiCZrC, TiCTiB₂ and TiCTiB₂ Co. The deposits were prepared by direct evaporation of TiB₂, ZrB₂, ZrC, TiC and cobalt from single and multiple water-cooled copper crucibles using electron beam heating. TiC and ZrC deposits were also prepared by the activated reactive evaporation process. The vapors were condensed on a molybdenum or tantalum substrate at various deposition temperatures ranging from 650 to 1600 °C. The deposition rate was varied from 0.08 to 6 μm min^?1The deposits were characterized by optical microscopy, scanning and transmission electron microscopy, X-ray and electron diffraction and microhardness determinations. With direct evaporation the deposits contained decomposition products in addition to the parent phases. The composition of the deposits was dependent on temperature of deposition, composition of the evaporant billet and to a small extent the rate of deposition. Deposition temperature, rate of deposition and the composition of the deposit influenced the preferred orientation and the microhardness of the deposits. Surface and fracture cross section morphology and microstructure varied with deposition temperature. The data represent an extensive characterization of refractory compound deposits made by high rate physical vapor deposition processes.     

Chemical vapour-deposited silicon nitride

Pyrolytic Si₃N₄ has been deposited on a graphite substrate, using a mixture of SiCl₄, NH₃ and H₂. The pyrolysis is performed with deposition temperatures of 1100 to 1500° C, total gas pressures of 5 to 300 Torr, and flow rates of H₂=700, NH₃=60 and SiCl₄ (liq.)=0.8 cm³ min^–1. Massive amorphous and crystalline pyrolytic forms of Si₃N₄ are prepared at a maximum thickness of 4.6 mm. The effects of deposition conditions on some properties of the deposited products and the dependence of formation of amorphous or crystalline deposits on deposition temperature and total pressure were investigated. The surface and cross-sectional structures show growth cones and oriented crystals which are strongly dependent on the deposition conditions. The thin deposits are translucent; the thick deposits vary in colour from white to black. The silicon content is close to the theoretical composition and independent of the deposition conditions, while the oxygen content increases with decreasing deposition temperature and total pressure. No segregation of silicon and nitrogen at cone boundaries was found.     

Physical properties of tin oxide films deposited by oxidation of SnCl2

Highly transparent and conducting SnO₂ films, as required in thin film heterojunction solar cells, were deposited onto Pyrex glass substrates by oxidation of SnCl₂ in the temperature range 350–500°C. Oxygen with a flow rate of between 1 and 3.251 min^-1 was used as both the carrier gas and the oxidizing agent. For films deposited in these conditions the resistivity varies from 10^-2 to 10^-3 Ω cm with transmission in the range 87%–71%. It was observed that both the resistivity and the transmission decrease with increasing deposition temperature. The resistivity of films deposited at a fixed deposition temperature passes through a minimum as the oxygen flow rate is increased. Hence, SnO₂ films with low resistivity and high transmission can be produced by the oxidation of SnCl₂ at relatively low temperatures using the oxygen flow rate corresponding to the minimum resistivity. For example, in the present work, low resistivity (4.4 × 10^-3 Ω cm) and high transmission (87%) were observed for films deposited at 400°C with an oxygen flow rate of 1.81 min^-1. The effects of the deposition temperature, oxygen flow rate and deposition time on the thickness, deposition rate, resistivity and absorption coefficient are discussed in detail.     

Chemical vapour deposition of titanium oxides in the composition range TiO1.60–TiO1.75

Ti₃O₅ and Ti₄O₇ were grown by chemical vapour deposition in a hot-wall reactor at 1015 °C and a total pressure of 50 Torr. The reaction gas mixture contained TiCl₄, CO₂ and H₂. For growth of single-phase coatings the vapour composition has to be controlled accurately. Ti₃O₅ was grown at near-equilibrium conditions, while Ti₄O₇ could only be grown under conditions far from equilibrium. The coatings grew at a rate of about 0.3 microm min^?1 and consisted of well-shaped columnar crystals.     

Pressure-pulsed chemical vapour infiltration of TiN to SiC particulate preforms

SiC particulate preforms were infiltrated by TiN matrix from a gas mixture of TiCl₄ (5%), nitrogen (30%) and hydrogen using a repeating pressure pulse between 760 and about 1 torr. SiC particle sizes of 5 and 20 m were used. For matrix packing into deep level, optimum temperature was determined between 800 and 850 °C, and the maximum packing ratio reached 67% after 4 × 10⁴ pulses at 850 °C. The increase of TiCl⁴ concentration to 10% resulted in higher deposition rate and packing ratio. The decrease of nitrogen concentration led to slower deposition, that is, a similar effect to temperature lowering. The maximum flexural strength measured was 140 MPa.     

The growth characteristics of chemical vapour-deposited β-SiC on a graphite substrate by the SiCl4/C3H8/H2 system

Silicon carbide has been grown at 1300–1800°C by chemical vapour deposition using the SiCl₄/C₃H₈/H₂ system on a graphite substrate. The effect of C₃H₈ flow rate and deposition temperature on the growth characteristics and structure of the deposit has been studied. The experimental results show that the degree of film density is changeable from a dense plate to a porous one with increasing C₃H₈ flow rate. The activation energy increases with increasing C₃H₈ flow rate. The grain size of the polycrystalline β-SiC becomes coarser when the C₃H₈ flow rate and the deposition temperature are increased. The preferred orientation of the deposited SiC layers changes from (111) to (220) on increasing deposition temperature from 1300°C to 1400°C. The deposition mechanism is also discussed.     

Structural,electrical and optical properties of r.f.-magnetron-sputtered SnO2:Sb film

The effects of gas composition, pressure and substrate temperature on the properties of relatively thick (0.2–0.8 μm) SnO₂ films deposited onto fused quartz substrates by r.f. magnetron sputtering are reported. The lowest resistivity of about 2 × 10^?3ωcm was attained for high rate deposition conditions of about $\text{1000}\text{A}\text{?}\text{min}{}^{\mathrm{?1}}$ on substrates at a temperature of 400°C in an atmosphere of 10% O₂. This value corresponds to a carrier density of 3 × 10²⁰cm^?3 and a mobility of 10 cm²V^?1s^?1. The crystal structure was found to be sensitive to all the above parameters. Low resistivity films showed a highly preferred orientation of (101) parallel to the substrate.     

Deposition characteristics and properties of iron nitride films by CVD using organometallic compound

Iron nitride films were prepared by chemical vapour deposition from the gas mixture of Fe(C₅H₅)₂-NH₃-H₂-CO₂. The effects of deposition parameters on the deposition characteristics were investigated. Iron nitride films were deposited above 500 ° C and the films of -Fe₄N single phase were deposited above 700 ° C. At 700 ° C and under the total gas flow rate from 1 to 8 l min^–1, the deposition rate of the film may be controlled by the transport of Fe(C₅H₅)₂ molecules to the surface of the deposits. At 700 °C and under the total gas flow rate of 4 l min^–1, the phases and nitrogen contents of the films were determined bypNH₃/pH₂ ^3/2, the controlling factor of the nitrogen contents of the films. Decreasing of the total gas flow rate and increasingpCO₂ increased the nitrogen contents of the films and phases with higher nitrogen were deposited. On the other hand, increasingpFe(C₅H₅)₂ and the absence ofpCO₂ increases the carbon contents of the films, and the phase with a greater solubility in carbon, i.e. -Fe₂N, was codeposited with -Fe₄N. The saturation magnetization of the films deposited at 700 ° C was in good agreement with that reported for the bulk iron nitride, which depended not on the deposition conditions but on the nitrogen contents of the films.