Hot filament CVD growth of polycrystalline diamond films and its characterisation (original) (raw)
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Diamond single crystal growth in hot filament CVD
Diamond and Related Materials, 2006
The synthesis of diamond crystals is of particular interest due to the material's outstanding physical and mechanical properties. In hot filament CVD (HFCVD) we found a new process parameter window where the growth of single diamond volume crystals can be stabilized without the use of monocrystalline substrates. These CVD parameters are far beyond growth conditions for HFCVD diamond coating processes. Extremely low methane contents in the feed gas along with high substrate temperatures allow single diamond nuclei of a sufficiently large size to grow stabile. Crystals up to 80 μm in diameter were successfully synthesized. The morphology of the crystals is cubo-octaedric. According to our proposed growth model [S.
Enhanced Diamond Film Growth by Hot-Filament CVD Using Forced Convection
Physica Status Solidi (a), 1996
Diamond film growth in hot filment CVD can be enhanced by applying forced convection. This method facilitates an increase of deposition rates up to about 5 pm/h. In the presented HFCVD system growth rates reach a maximum of about 3.3 pm/h at gas velocities of about 1000 m/s and diminish rapidly for higher velocities. Measurements of atomic hydrogen generation by determination of electrical power consumption by the filaments in hydrogen and helium show that this effect is not caused by a kinetic limitation of H generation at the filaments. The generation of H is an approximately linear function of gas velocity and filament diameter for the considered gas velocity range. Measured H generation rates were used as input for a simple one-dimensional model developed to describe the transport of atomic hydrogen and methyl, the assumed main diamond growth species, to the substrate. The calculations show a kinetic limitation of methyl concentration in the vicinity of the substrate surface due to too high convective transport velocities and can qualitatively explain the observed growth rate minimum. ~ ~~~ l ) Bienroder Weg 54E, D-38108 Braunschweig, Federal Republic of Germany. 3 physica (a) 154/1
Effect of substrate roughness on growth of diamond by hot filament CVD
Bulletin of Materials Science, 2010
Polycrystalline diamond coatings are grown on Si (100) substrate by hot filament CVD technique. We investigate here the effect of substrate roughening on the substrate temperature and methane concentration required to maintain high quality, high growth rate and faceted morphology of the diamond coatings. It has been shown that as we increase the substrate roughness from 0⋅05 μm to 0⋅91 μm (centre line average or CLA) there is enhancement in deposited film quality (Raman peak intensity ratio of sp 3 to non-sp 3 content increases from 1⋅65 to 7⋅13) and the substrate temperature can be brought down to 640°C without any additional substrate heating. The coatings grown at adverse conditions for sp 3 deposition has cauliflower morphology with nanocrystalline grains and coatings grown under favourable sp 3 condition gives clear faceted grains.
Combined HF+MW CVD Approach for the Growth of Polycrystalline Diamond Films with Reduced Bow
Combined HF+MW CVD Approach for the Growth of Polycrystalline Diamond Films with Reduced Bow, 2023
A combination two methods of chemical vapor deposition (CVD) of diamond films, microwave plasma assisted (MW CVD) and hot filament (HF CVD), is used for the growth of 100µ mthick polycrystalline diamond (PCD) layer on the Si substrate. The bending of HF CVD and MW CVD films showed opposite convex\concave trends, so the combined material allowed to reduce overall bending by a factor of 2 ÷ 3. Using MW CVD for the growth of the initial 25µ m-thick PCD layer allowed to achieve much higher thermal conductivity of the combined 110µ m-thick film at 210 W/m·K in comparison to 130 W/m·K for the pure 93µ m-thick pure HF CVD film.
CVD diamond films: from growth to applications
Current Applied Physics, 2001
The present review provides an up-to-date report on the main potential of CVD diamond films for industrial applications as well as on recent basic research which seeks to understand diamond deposition microwave plasma reactors. This review includes firstly an overview of diamond film applications. Elements which explain variations in diamond film characteristics as a function of synthesis conditions are given. Also experimental results are reported which show variations in diamond characteristics (quality, microstructure, growth rate, growth mechanisms) as four plasma variables (pressure, power, percentage of methane, substrate temperature) are systematically changed. In the second part, we discuss the effects of these variables on local parameters such as electron temperature, gas temperature, carbon-containing species and H-atom densities. Finally, based on these results, relationships between key local parameters and diamond characteristics are established and discussed. Ó
Diamond and Related Materials, 2004
In this work, structure and mechanical properties of diamond films fabricated by HFCVD on silicon substrates with nanodiamond seeding were investigated. Raman spectroscopy was used to characterise the diamond phase content, crystalline quality and source of stresses in these films. Topography, hardness and Young's modulus were studied by scanning force microscopy (SFM) and nanoindentation methods. It has been ascertained that for the diamond films grown on silicon substrates with nanodiamond seeding hardness and crystalline quality is higher than for films on scratched silicon. The diamond films demonstrate Raman upshift with respect to natural diamond, indicating presence of internal compressive stress. It was shown that various types of impurities and defects induce compressive stresses in the diamond grains. ᮊ
Diamond and Related Materials, 2002
The pressure dependence of the growth rate, quality and morphology of CVD-diamond films in an industrial hot-filament plant (CC800D) were investigated by SEM and Raman. Additionally, the concentration of atomic hydrogen near the filament was determined via a calorimetric measurement method. At a substrate temperature of 850 8C the smallest growth rate (0.1 mmyh) and the best quality of diamond coatings were obtained at the pressure with the highest hydrogen concentration (20 mbar). The growth rate increases strongly with decreasing pressure and achieves the maximum value of 0.7 mmyh at 3 mbar. At the same time the diamond coating quality decreases. ᮊ
Journal of Nanoscience and Nanotechnology, 2009
In this work we have investigated the effect of substrate temperature on the growth rate and properties of nanocrystalline diamond thin films deposited by hot filament chemical vapor deposition (HFCVD). Mixtures of 0.5 vol% CH 4 and 25 vol% H 2 balanced with Ar at a pressure of 50 Torr and typical deposition time of 12 h. We present the measurement of the activation energy by accurately controlling the substrate temperature independently of other CVD parameters. Growth rates have been measured in the temperature range from 550 to 800 C. Characterization techniques have involved Raman spectroscopy, high resolution X-ray difractometry and scanning electron microscopy. We also present a comparison with most activation energy for micro and nanocrystalline diamond determinations in the literature and propose that there is a common trend in most observations. The result obtained can be an evidence that the growth mechanism of NCD in HFCVD reactors is very similar to MCD growth.
Bulletin of Materials Science, 2014
Polycrystalline diamond thin films with outgrowing diamond (OGD) grains were deposited onto silicon wafers using a hydrocarbon gas (CH 4) highly diluted with H 2 at low pressure in a hot filament chemical vapour deposition (HFCVD) reactor with a range of gas flow rates. X-ray diffraction (XRD) and SEM showed polycrystalline diamond structure with a random orientation. Polycrystalline diamond films with various textures were grown and (111) facets were dominant with sharp grain boundaries. Outgrowth was observed in flowerish character at high gas flow rates. Isolated single crystals with little openings appeared at various stages at low gas flow rates. Thus, changing gas flow rates had a beneficial influence on the grain size, growth rate and electrical resistivity. CVD diamond films gave an excellent performance for medium film thickness with relatively low electrical resistivity and making them potentially useful in many industrial applications.
The diamond growth–CVD Assisted by hot filament in silicon substrate in 80 cm 2 areas
2008
Nowadays, the diamond grown by chemical vapor deposition (CVD) is seen economically as one of the most interesting materials, due to its vast application, mainly in shortterm, resulting from diamond's unique properties. Its applications reach many technological areas, standing out the mechanics area due to possibilities use as cutting tools, tribological layers in automobiles and aeronautical engines, heat sinks, surfaces protection for aggressive environments and abrasive special devices which also add applications in biological areas. The largest obstacle for these applications is the high cost of diamond films production if compared commercially with other alternative materials. So, the area and the growth rate increasing is a solution for the costs reduction in the diamond production. The CVD diamond samples used in this work had been grown in a big reactor, for growth in big areas, by the hot filament chemical vapor deposition technique (HFCVD). The precursory mixture of 2% of methane in hydrogen was maintained by a of 50 mbar pressure for a E2M8-Boc Edwards vacuum pump. The substrate used in the growths was silicon (100) with 100mm of diameter. The growth temperature was maintained in (800 ± 20) °C and the growth time was changeable until about 50 h, when it had the breaks of the substrate. The diamond growth rate measured (0,7 ± 0,1) µm/h is low for economic viability of the process. The spectroscopy of Raman scattering analysis evidences the diamond growth of good quality, approximately in one area of 80 cm 2 , with minimum compressive stress. The properties and the diamond growth rates the surfaces of the used substrate had been uniform. The reached development allows diamond growth 30 µm thickness in 80 cm 2 areas, without breaking of the substrate.