Deposition Of Nanocrystalline Diamond Films Research Articles

Poly-adamantane as precursor for low temperature chemical vapor deposition of nanocrystalline diamond films

Nanocrystalline diamond (NCD) films are technologically important tribological coatings and their large area, uniform growth is needed for a wide range of applications. The conventional growth of NCD requires the seeding of the foreign substrates by detonation nanodiamond particles. In terms of diamond seeds for subsequent NCD film deposition, the use of chemical precursor offers advantages in producing higher purity and higher crystallinity nanodiamond particles than that by detonation method. However, the easy sublimation of chemical precursor in plasma is a serious drawback. Here we report that the poly-adamantane layer formed by the photochemically induced polymerization of adamantane serves as a promising precursor for the growth of wafer scale NCD film using linear antenna plasma-assisted chemical vapor deposition at 500 °C. TEM cross-section analysis of the interface reveals the formation of well-faceted diamond nuclei within the amorphous carbon matrix (sp 3 % ~ 40 %) decomposed from poly-adamantane. The influence of plasma chemistry on the nucleation process was also discussed. Our work provides guidance for low-temperature deposition of high-quality NCD film by chemical nucleation. • Deposition of 4-in. nanocrystalline diamond wafer using 230 nm-thick poly-adamantane precursor layer • Cross-sectional TEM study of diamond nuclei derived from poly-adamantane precursor • Study of plasma chemistry on nucleation process by poly-adamantane precursor • Film quality control by poly-adamantane precursor at low temperature

Effect of the admixture of N2 to low pressure, low temperature H2-CH4-CO2 microwave plasmas used for large area deposition of nanocrystalline diamond films

In a distributed antenna array reactor, microwave H2-CH4-CO2 plasmas with admixture of N2 used for the low-temperature deposition of nanocrystalline diamond (NCD) films are studied by in situ infrared laser absorption spectroscopy (LAS) and optical emission spectroscopy techniques. The experiments are carried out in order to analyze the dependence of temperatures and species densities as a function of the admixture of nitrogen. The evolution of the concentrations of the methyl radical (CH3), and of five stable molecules (NH3, HCN, CH4, C2H2, and CO), are monitored in the plasma processes by LAS using tunable lead salt diode lasers and external-cavity quantum cascade lasers (EC-QCL) as radiation sources. OES is performed simultaneously to obtain complementary information about (i) the degree of dissociation of H2 precursor gas, (ii) the gas temperature and therefore (iii) the density of atomic hydrogen, a key species in the chemistry of NCD deposition plasmas. The species temperatures are not significantly affected by the nitrogen addition. The concentrations of the various species are in the range between 1011 to 1015 molecules cm−3. HCN and CO are the major products in the plasma besides atomic hydrogen. The analysis of the nitrogen and carbon mass balances of the measured species shows that in addition to NH3 and HCN other nitrogen containing species are produced in the plasma which were not probed. It is shown that the formation of HCN consumes C atoms that can be provided from hydrocarbon species and from the deposition of carbon-containing films on the reactor walls, which results in a decrease of the measured densities of hydrocarbon species.

Gaseous boronizing pretreatment for the deposition of nanocrystalline diamond films on cemented carbide substrates

A simple and efficient method-vacuum heat treatment gaseous boronizing was proposed to pretreat the YG6X cemented carbides for maintaining its toughness and strength of the pretreated cemented carbide, and promising for mass production. After this pretreatment, the substrate surface remained clean, and the nanocrystalline diamond (NCD) films were deposited on the pretreated cemented carbide by hot filament chemical vapor deposition (HFCVD) with methane, hydrogen and argon as reaction gases. The morphology, structure, roughness and film-substrate adhesion strength of the cemented carbide substrate and the diamond films were analyzed by x-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman spectroscopy and adhesion performance test. The results show that this method of gaseous boronizing is stable and feasible. The boride layer with high temperature stability can be formed. The microhardness of the cemented carbide surface after boronizing treatment was increased by 18% compared with that of the original untreated one. The comprehensive treatment of the alkali etching followed by boronizing is more effective to improve the film-substrate adhesion performance than the two-step chemical etching pretreatment.

Study of Low Temperature Deposition of Nanocrystalline Diamond Films on ZnO/LiNbO3 Layered Structures Suitable for Waveguiding Layer Acoustic Wave Devices

In this article, the nanocrystalline diamond (NCD) film low temperature deposition process on ZnO/Si, ZnO/LiNbO3, and ZnO/IDTs/LiNbO3 substrates is investigated aiming at obtaining layered structures suitable for waveguiding layer acoustic wave (WLAW) devices. The NCD synthesis is performed at 250 °C by using a distributed antenna array (DAA) microwave system operating in H2/CH4/CO2 gas mixture at low pressure (<1 mbar). Since the ZnO layer is etched during the NCD growth process, the deposition of a thin AlN layer of few hundred nanometers in thickness on the considered substrates is performed and is shown to be effective as a protective layer. Diamond growth on AlN‐coated ZnO/Si substrates emphasizes the ability of the DAA reactor to synthesize NCD films with properties similar to those obtained on silicon substrates. Besides adherent NCD films up to 300 nm thickness are synthesized on AlN‐coated ZnO/LiNbO3 substrates but stress in the layered structure appears during the plasma process. Finally, the feasibility of a NCD/AlN/ZnO/IDTs/LiNbO3 layered structure, suitable for WLAW devices, is successfully demonstrated, even if the NCD film adherence must be further improved on the inter‐digital transducers (IDTs) finger zone.

Nanocrystalline diamond films grown at very low substrate temperature using a distributed antenna array microwave process: Towards polymeric substrate coating

The growth of NanoCrystalline Diamond (NCD) films at very low substrate temperature on large area surface using a distributed antenna array (DAA) microwave reactor operating in H2/CH4/CO2 gas mixture is investigated. The estimated activation energy is in the range 1.3–3.2kcal·mol−1 depending on the injected microwave power and resulting substrate temperature range, which is comparable to values reported for other low-temperature NCD growth processes. The ability of the DAA reactor to deposit NCD films at a surface temperature down to 130°C is demonstrated. NCD films composed of nanometric grains of 4.5nm with a surface roughness of 27nm are thus obtained, with a growth rate of 5nm·h−1. The decrease of the deposition temperature is followed by an increase of the renucleation rate leading to a reduction of the grain size and to a subsequent promotion of non-diamond phases. At this temperature, the decrease of the CH4 percentage in the feed gas permits to improve the film purity but leads to a drastic decrease of the growth rate down to 2.5nm·h−1. Finally, a successful attempt of NCD film deposition on polytetrafluoroethylene (PTFE) substrate is shown aiming at exploring the coating of temperature-sensitive polymeric substrates employed for biomedical applications.

Spectroscopic study of low pressure, low temperature H2–CH4–CO2 microwave plasmas used for large area deposition of nanocrystalline diamond films. Part I: on temperature determination and energetic aspects

In a distributed antenna array (DAA) reactor, microwave H2 plasmas with admixtures of 2.5% CH4 and 1% CO2 used for the deposition of nanocrystalline diamond films have been studied by infrared absorption and optical emission spectroscopy (OES) techniques. The experiments were carried out in order to analyze the dependence of plasma chemical phenomena on power and pressure at relatively low pressures, up to 0.55 mbar, and power values, up to 3 kW. The evolution of the concentration of the methyl radical, CH3, and of five stable molecules, CH4, CO2, CO, C2H2 and C2H6, was monitored in the plasma processes by in situ infrared laser absorption spectroscopy using lead salt diode lasers (TDL) and external-cavity quantum cascade lasers (EC-QCL) as radiation sources. OES was applied simultaneously to obtain complementary information about the degree of dissociation of the H2 precursor gas and of its gas temperature. The experimental results are presented in two separate parts. In Part I, the present paper, the measurement of the gas (Tgas), rotational (Trot) and vibrational (Tvib) temperatures of the various species in the complex plasma was the main focus of interest. To achieve reliable values for the gas temperature inside and outside the plasma bulk as well as for the rotational and vibrational temperatures in the plasma hot zones, which are of great importance for calculation of species concentrations, five different methods based on the emission and absorption spectroscopy data of H2, CH4, CH3 and CO have been used. In these, line profile analysis has been combined with Boltzmann plot methods. Based on the wide tuning range of the EC-QCL, a variety of CO lines in the ground and three excited states was measured enabling extensive temperature analysis providing new insight into the energetic aspects of this multi-component plasma. Depending on the different plasma zones the gas temperature was found to range between about 360 and 1000 K inside the DAA reactor. In Part II, based on detailed concentration measurements general plasma chemical aspects will be analyzed and discussed.

Spectroscopic study of low pressure, low temperature H2–CH4–CO2 microwave plasmas used for large area deposition of nanocrystalline diamond films. Part II: on plasma chemical processes

In a distributed antenna array (DAA) reactor, microwave H2 plasmas with admixtures of 2.5% CH4 and 1% CO2 used for the deposition of nanocrystalline diamond films have been studied by infrared laser absorption and optical emission spectroscopy (OES) techniques. The experiments were carried out in order to analyze the dependence of plasma chemical phenomena on power and pressure at relatively low pressures, up to 0.55 mbar, and power values, up to 3 kW. The evolution of the concentration of the methyl radical, CH3, of five stable molecules, CH4, CO2, CO, C2H2 and C2H6, and of vibrationally excited CO in the first and second hot band was monitored in the plasma processes by in situ infrared laser absorption spectroscopy using tunable lead salt diode lasers (TDL) and an external-cavity quantum cascade laser (EC-QCL) as radiation sources. OES was applied simultaneously to obtain complementary information about the degree of dissociation of the H2 precursor and of its gas temperature. The experimental results are presented in two separate parts. In Part I, the first paper in a two-part series, the measurement of the gas (Tgas), rotational (Trot) and vibrational (Tvib) temperatures of the various species in the complex plasma was the main focus of interest. Depending on the different plasma zones the gas temperature was found to range between about 360 and 1000 K inside the DAA reactor (Nave et al 2016 Plasma Sources Sci. Technol. 25 065002). In Part II, the present paper, taking into account the temperatures determined in the first paper, the concentrations of the various species, which were found to be in a range between 1011 and 1015 cm−3, are the focus of interest. The influence of the discharge parameters power and pressure on the molecular concentrations has been studied. To achieve further insight into general plasma chemical aspects the dissociation of the carbon precursor gases including their fragmentation and conversion to the reaction products has been analyzed in detail.

Nanocrystalline Diamond Films Deformation Observed During Sliding Tests Against Si3N4 Balls

The study investigates wear performance of nanocrystalline diamond (NCD) films under reciprocating sliding conditions. The NCD films were grown by hot-filament chemical vapor deposition (HFCVD) method on (100) oriented Si wafers. The surface morphology was characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and mechanical profilometry. The study focuses on the understanding of mechanisms resulting in NCD films deformation and formation of ripple patterns on the wear scars surface observed during reciprocal sliding tests. Plastic deformation of the Si wafer due to NCD film deposition and high local contact pressure and temperature during sliding lead to structural changes on the Si(100)/NCD film interface, thus causing the NCD film to deform and the characteristic ripple patterns to develop on the wear scars surface. DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7232

Effect of metallic seed layers on the properties of nanocrystalline diamond films

Three metallic films (Mo, Ti and W) were sputtered on Si substrates and ultrasonically seeded in diamond powder suspension. Nanocrystalline diamond (NCD) films were deposited using a dc arc plasma jet CVD system on the seeded metallic layers and, for comparison, a seeded Si without any metallic layer. The effect of metallic seed layers on the nucleation, microstructure, composition and mechanical properties of NCD films was investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and nanoindentation. We found that the metallic seed layers were transformed into metallic carbide or/and metallic silicide during the deposition of NCD films at high temperature. Adding metallic seed layers had no obvious effect on the bonding structure of the NCD films but significantly improved their surface roughness and mechanical properties. The NCD film deposited on W seed layer displays the lowest root-mean-square roughness of 19nm while that on Ti seed layer has the highest compactness, hardness and elastic modulus.

Low temperature and large area deposition of nanocrystalline diamond films with distributed antenna array microwave-plasma reactor

Abstract Diamond films grown at low temperature ( 4 concentration in the total gas mixture of H 2 /CH 4 /CO 2 on the morphology and growth rate of the NCD films is reported. The total gas pressure is found to be a critical deposition parameter for which growth rates and crystalline quality both increasing with decreasing the pressure. Under optimized conditions, the process enables deposition of uniform (~ 10%) and high purity NCD films with very low surface roughness (5–10 nm), grain size of 10 to 20 nm at growth rates close to 40 nm/h. Nanotribology tests result in the friction coefficient of the NCD films close to that obtained for the standard tetrahedral amorphous carbon coatings (ta-C) indicating the suitability of this low-temperature diamond coating for mechanical applications such as bearing or micro-tools.

Microwave plasma enhanced chemical vapor deposition of nanocrystalline diamond films by bias-enhanced nucleation and bias-enhanced growth

Effects of biasing voltage-current relationship on microwave plasma enhanced chemical vapor deposition of ultrananocrystalline diamond (UNCD) films on (100) silicon in hydrogen diluted methane by bias-enhanced nucleation and bias-enhanced growth processes are reported. Three biasing methods are applied to study their effects on nucleation, growth, and microstructures of deposited UNCD films. Method A employs 320 mA constant biasing current and a negative biasing voltage decreasing from −490 V to −375 V for silicon substrates pre-heated to 800 °C. Method B employs 400 mA constant biasing current and a decreasing negative biasing voltage from −375 V to −390 V for silicon pre-heated to 900 °C. Method C employs −350 V constant biasing voltage and an increasing biasing current up to 400 mA for silicon pre-heated to 800 °C. UNCD nanopillars, merged clusters, and dense films with smooth surface morphology are deposited by the biasing methods A, B, and C, respectively. Effects of ion energy and flux controlled by the biasing voltage and current, respectively, on nucleation, growth, microstructures, surface morphologies, and UNCD contents are confirmed by scanning electron microscopy, high-resolution transmission-electron-microscopy, and UV Raman scattering.

Application of Nitrogen-Doped Nanocrystalline Diamond Film on Partially Stabilized Zirconia for Pulverization Disk

ABSTRACTWe report here partially stabilized zirconia (PSZ) matrix deposited with nanocrystalline diamond (NCD) films on its surface as an alternative material for pulverization disk with a potential of substituting high cost synthetic single crystal diamond. The deposition of NCD films on PSZ improved the characterization of the desorption-oxygen from PSZ matrix and enhanced the poor adhesion strength between NCD film and PSZ when N2 was used as doping gas. The results for X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirmed that with increasing N2 flow rate, nitrogen and desorption-oxygen were incorporated into film. The adhesion test and the pulverization test showed that enhancement in the adhesion strength as well as in the pulverization performance with increasing nitrogen and oxygen concentration in the NCD films. The results proposed to substitute a synthetic single crystal diamond with PSZ by coating nitrogen-doped NCD film.

Deposition of Nano-Crystalline Diamond Films of Spherical Shell

Deposition of Nano-Crystalline Diamond Films of Spherical Shell

The Deposition of Nanocrystalline Diamond by HFCVD in Different Materials

Nanocrystalline diamond films, as other forms of diamond, possess a set of extreme properties, such as high thermal conductivity, hardness and resistance to hazard environments. Although an enormous focus has been placed into the deposition of nanocrystalline diamond films, most of this research uses microwave plasma assisted CVD systems. However, the growth conditions used in microwave systems cannot be directly used in hot-filament CVD systems. In this paper, it is meant to enlarge the knowledge of the process of depositing nanocrystalline films on different engineering materials, by means of hot-filament CVD systems. The coated materials include silicon (Si); titanium (Ti); tungsten carbide with cobalt as binder (WC-Co); and tungsten carbide with nickel as binder (WC-Ni). On the former two substrates, the diamond films were achieved on the bare substrates and with the use of an interlayer. The interlayers used were chromium nitride (CrN) and titanium aluminium nitride (TiAlN). Additionally, the as-grown films were characterized for hardness, quality and microstructure using scanning electron microscopy, Raman spectroscopy and nanohardness testing.

Process Control of CVD Deposition of Nanocrystalline Diamond Films by Plasma Diagnostics

Abstract Ultrananocrystalline Diamond (UNCD) Films were deposited by MW-CVD from an Ar/H2/CH4 plasma. The plasma properties were measured in situ by optical emission spectroscopy and mass spectroscopy. The intensity of the C2 emission line was systematically varied as a key plasma parameter and a correlation with resulting film properties was found.

Deposition of nanocrystalline diamond films on temperature sensitive substrates for infrared reflectance spectroscopy

We report on the deposition of nanocrystalline diamond films onto protected aluminum/pyrex glass mirrors in focused or linear antenna microwave plasma enhanced chemical vapour deposition systems. Quality of the diamond films is characterized by Raman spectroscopy, scanning electron microscopy and optical images. The best material quality and coating uniformity is achieved in the linear antenna system. Infrared reflectance spectroscopy reveals enhanced reflection from the substrates prepared in the linear antenna system compared to diamond coatings prepared in common focused plasma system on protected aluminium/pyrex glass mirrors as well as on polished Si wafers. Linear antenna system diamond coatings are thus the most promising for spectroscopic characterization of molecular grafting to diamond.

Effect of microwave power and C 2 emission intensity on structural and surface properties of nanocrystalline diamond films

Nanocrystalline diamond (NCD) films are synthesized using microwave plasma enhanced chemical vapour deposition technique at 2 × 10 4 Pa and 600 °C with microwave power of 600–1600 W. Deposition is carried out on n-type (100) silicon wafer with Ar/H 2/CH 4 gas mixtures. The film properties are analyzed using micro Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy and atomic force microscopy. Raman spectra show two predominant peaks centered around 1335 cm −1 and 1560 cm − 1 and two humps around 1160 cm − 1 and 1450 cm − 1 , respectively. FTIR spectra show C:H stretching modes around 3000 cm − 1 . XRD patterns show a peak at 44° (2θ). In situ diagnostic of plasma is carried out using Optical Emission Spectroscopy. It has been observed that C 2 dimer plays an important role in the nucleation of diamond crystals during NCD film deposition and the emission intensity of C 2 can be adjusted by varying the microwave power. It has also been observed that the structural properties like growth rate, surface morphology and grain size of the growing film are dependent on the C 2 intensity during deposition.

Effect of Gas Sources on the Deposition of Nano-Crystalline Diamond Films Prepared by Microwave Plasma Enhanced Chemical Vapor Deposition

Nano-crystalline diamond (NCD) films were deposited on silicon substrates by a microwave plasma enhanced chemical vapor deposition (MPCVD) reactor in C2H5OH/H2 and CH4/H2/O2 systems, respectively, with a constant ratio of carbon/hydrogen/oxygen. By means of atomic force microscopy (AFM) and X-ray diffraction (XRD), it was shown that the NCD films deposited in the C2H5OH/H2 system possesses more uniform surface than that deposited in the CH4/H2/O2 system. Results from micro-Raman spectroscopy revealed that the quality of the NCD films was different even though the plasmas in the two systems contain exactly the same proportion of elements. In order to explain this phenomenon, the bond energy of forming OH groups, energy distraction in plasma and the deposition process of NCD films were studied. The experimental results and discussion indicate that for a same ratio of carbon/hydrogen/oxygen, the C2H5OH/H2 plasma was beneficial to deposit high quality NCD films with smaller average grain size and lower surface roughness.

Graphitized filament plasma enhanced CVD deposition of nanocrystalline diamond

A novel approach to the deposition of polycrystalline diamond is presented. The technique is based on the hot filament chemical vapour deposition technique (HFCVD). While it is similar to a high plasma power “bias enhanced growth” HFCVD, it relies on a graphite filament rather than on a metal one. It was found that with an appropriate choice of the growth parameters, 4–9% CH 4 in H 2, filament temperature > 2200 °C, 25 mBar gas pressure, plasma power > 500 W, a long filament lifetime can be achieved, when a simultaneous deposition of graphitic carbon on the hot graphite filament and of nanocrystalline diamond on a substrate facing the filament assembly is realized. In this paper the growth of nanocrystalline diamond films and their characterization (SEM, XRD, AFM) are presented. While the technique is promising for low cost, large area deposition of nanocrystalline diamond films, also the growth of microcrystalline diamond has been observed.

Large-area surface wave plasmas using microwave multi-slot antennas for nanocrystalline diamond film deposition

An advanced slot antenna was developed and the enlargement of surface wave plasma was experimentally investigated using the array configuration of slot antennas for large-area nanocrystalline diamond (NCD) film depositions. An original-geometry slot antenna with an annular shape, designed in this work, permitted broad microwave radiations and vast extent of plasma propagations. Uniform plasmas were produced over a deposition area of 600 × 360 mm2 with densities of ∼1017 m−3 using hydrogen gas by an array configuration of five slot antennas and four rows of the array. A uniform (thickness variation: 10%) and smooth (Ra: 11 nm) NCD film deposition on a 300 × 300 mm2 borosilicate glass plate was achieved using the plasma and a mixed gas of H2/CH4/CO2.