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1.
The smooth ultra-nanocrystalline diamond (UNCD) films were prepared by microwave plasma chemical vapor deposition (MWCVD) using argon-rich CH4/H2/Ar plasmas with varying argon concentration from 96% to 98% and negative bias voltage from 0 to −150 V. The influences of argon concentration and negative bias voltage on the microstructure, morphology and phase composition of the deposited UNCD films are investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), atom force microscopy (AFM), and visible and UV Raman spectroscopy. It was found that the introduction of argon in the plasma caused the grain size and surface roughness decrease. The RMS surface roughness of 9.6 nm (10 micron square area) and grain size of about 5.7 nm of smooth UNCD films were achieved on Si(100) substrate. Detailed experimental results and mechanisms for UNCD film deposition in argon-based plasma are discussed. The deposited highly smooth UNCD film is also expected to be applicable in medical implants, surface acoustic wave (SAW) devices and micro-electromechanical systems (MEMS). 相似文献
2.
The fabrication of a well-adherent diamond film on titanium and its alloys is always problematical due to the different thermal expansion coefficients of the two materials, the complex nature of the interlayer formed during diamond deposition, and the difficulty in achieving very high nucleation density. In this work, well-adherent and smooth nanocrystalline diamond (NCD) thin film is successfully deposited on pure titanium substrate by microwave plasma-assisted chemical vapor deposition (MWPCVD) method in Ar/CH4 environment. It is found that the average grain size is less than 20 nm with a surface roughness value as low as 12 nm. Morphology, surface roughness, diamond crystal orientation and quality are obtained by characterizing the sample with field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy, respectively. Detailed experimental results and mechanisms for NCD film deposition are discussed. 相似文献
3.
Rishi Sharma Nicolas WoehrlMilan Vru?ini? Monika TimpnerVolker Buck P.K. Barhai 《Thin solid films》2011,519(22):7632-7637
Nanocrystalline diamond (NCD) films are synthesized using microwave plasma enhanced chemical vapour deposition technique at 2 × 104 Pa and 600 °C with microwave power of 600-1600 W. Deposition is carried out on n-type (100) silicon wafer with Ar/H2/CH4 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 C2 dimer plays an important role in the nucleation of diamond crystals during NCD film deposition and the emission intensity of C2 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 C2 intensity during deposition. 相似文献
4.
Silicon carbide (SiC) thin films were prepared by hot-wire chemical vapor deposition from SiH4/CH4/H2 and their structural properties were investigated by X-ray diffraction, Fourier transform infrared absorption and Raman scattering spectroscopies. At 2 Torr, Si-crystallite-embedded amorphous SiC (a-Si1 − xCx:H) grew at filament temperatures (Tf) below 1600 °C and nanocrystalline cubic SiC (nc-3C-SiC:H) grew above Tf = 1700 °C. On the other hand, At 4 Torr, a-Si1 − xCx:H grew at Tf = 1400 °C and nc-3C-SiC grew above Tf = 1600 °C. When the intakes of Si and C atoms into the film per unit time are almost the same and H radicals with a high density are generated, which takes place at high Tf, nc-3C-SiC grows. On the other hand, at low Tf the intake of Si atoms is larger than that of C atoms and, consequently, Si-rich a-Si1 − xCx:H or Si-crystallite-embedded a-Si1 − xCx:H grow. 相似文献
5.
A high electron density (> 1011 cm− 3) and low electron temperature (1-2 eV) plasma is produced by using a microwave plasma source utilizing a spoke antenna, and is applied for the high-rate synthesis of high quality microcrystalline silicon (μc-Si) films. A very fast deposition rate of ∼ 65 Å/s is achieved at a substrate temperature of 150 °C with a high Raman crystallinity and a low defect density of (1-2) × 1016 cm− 3. Optical emission spectroscopy measurements reveal that emission intensity of SiH and intensity ratio of Hα/SiH are good monitors for film deposition rate and film crystallinity, respectively. A high flux of film deposition precursor and atomic hydrogen under a moderate substrate temperature condition is effective for the fast deposition of highly crystallized μc-Si films without creating additional defects as well as for the improvement of film homogeneity. 相似文献
6.
Diamond thin films were grown by linear antenna microwave plasma CVD process over large areas (up to 20 × 10 cm2) from a hydrogen based gas mixture. The influence of the gas composition (H2, CH4, CO2) and total gas pressure (0.1 and 2 mbar) on the film growth is presented. For CH4/H2 gas mixtures, the surface crystal size does not show dependence on the methane concentration and total pressure and remains below 50 nm as observed by SEM. Adding CO2 (up to 10%) significantly improves the growth rate. However, still no significant change of morphology is observed on films grown at 2 mbar. The crucial improvement of the diamond film purity (as detected by Raman spectroscopy) and crystal size is found for deposition at 0.1 mbar. In this case, crystals are as large as 500 nm and the growth rate increases up to 38 nm/h. 相似文献
7.
Diamond films were synthesized by direct current plasma chemical vapour deposition using a CH4+CO2+H2 gas mixture on Si substrates. The optimum deposition conditions were determined. It was found that 0.4 A/cm2 current density, at applied voltage of 1 kV, resulted in good-quality diamond films. The substrate temperature was 750 K which is considerably lower than the conventional requirement of ∼1100 K. Boron doping was achieved by passing a portion of the gas mixture through boric acid dissolved in methanol. The boron-doped p-type diamond films were deposited on an n-type single crystalline Si substrate and an n-Si/p-diamond heterojunction was fabricated. The p-n junction was characterized in terms of current-voltage (I-V) and capacitance-voltage (C-V) measurements. 相似文献
8.
Effect of doping elements on the etching characteristics of doped-ZnO (Ag, Li, and Al) thin films, etched with a positive photoresist (PR) mask, and an etch process window for infinite etch selectivity were investigated by varying the CH4 flow ratio and self-bias voltage, Vdc, in inductively coupled CH4/H2/Ar plasmas. Increased doping of ZnO films decreased the etch rates significantly presumably due to lower volatility of reaction by-products of doped Li, Ag, and Al in CH4/H2/Ar plasmas. The etch rate of AZO (Al-doped ZnO) was most significantly decreased as the doping concentration is increased from 4 to 10 wt%. It was found that process window for infinite etch selectivity of the doped ZnO to the PR is closely related to a balance between deposition and removal processes of a-C:H (amorphous hydrogenated carbon) layer on the doped-ZnO surface. Measurements of optical emission of the radical species in the plasma and surface binding states by optical emission spectroscopy (OES) and X-ray photoelectron spectroscopy (XPS), respectively, implied that the chemical reaction of CH radicals with Zn atoms in doped-ZnO play an important role in determining the doped-ZnO etch rate together with an ion-enhanced removal mechanism of a-C:H layer as well as Zn(CHx)y etch by-products. 相似文献
9.
Amorphous silicon carbonitride (a-SiCN) thin films were synthesized in a microwave plasma assisted chemical vapor deposition system using N2, Ar, CH4 and hexamethyldisilazane vapor (HMDSN). Composition, morphology and optical constants of the layers have been studied as a function of CH4 rate in the range 0 to 9%. It was found that films are mainly composed of silicon nitride like compound whatever the CH4 rate. However, CH4 addition leads to less hydrogenated and denser films. In addition, a refractive index augmentation from 1.7 to 2.0 and a Tauc gap decrease from 5.2 eV to 4.8 eV is measured with CH4 rate increase. It is believed that the refractive index augmentation is due to higher thin film density whereas hydrogen bonds decrease is assumed to contribute to the band gap narrowing. Besides, CH4 addition to the gaseous mixture increases thin film oxidation resistance. These results show the ability of varying composition, structure and optical constants of a-SiCN films by modifying CH4 rate in a N2/Ar/HMDSN plasma. 相似文献
10.
Jhantu K. Saha 《Thin solid films》2007,515(9):4098-4104
The plasma parameter for fast deposition of highly crystallized microcrystalline silicon (μc-Si) films with low defect density is presented using the high-density and low-temperature microwave plasma (MWP) of a SiH4-H2 mixture. A very high deposition rate of ∼ 65 Å/s has been achieved at SiH4 concentration of 67% diluted in H2 with high Raman crystallinity Ic / Iα > 3 and low defect density of 1-2 × 1016 cm− 3 by adjusting the plasma condition. Contrary to the conventional rf plasma, the defect density of the μc-Si films strongly depend on substrate temperature Ts and it increased with increasing Ts despite Ts below 300 °C, suggesting that the real surface temperature at the growing surface was higher than the monitored value. The sufficient supply of deposition precursors such as SiH3 at the growth surface under an appropriate ion bombardment was effective for the fast deposition of highly crystallized μc-Si films as well as the suppression of the incubation and transition layers at the initial growth stage. 相似文献
11.
In order to investigate the effects of argon and oxygen on diamond synthesis, the behaviors of diamond deposition using microwave plasma chemical vapor deposition method have been studied by varying the concentrations of argon and oxygen in the methane-hydrogen gas mixture. Diamond films were deposited on silicon wafer under the conditions of substrate temperatures: 1073 1173 K, total reaction pressure: 5333 Pa (40 Torr), methane concentrations: 0.5 5.0%, and they were characterized by scanning electron microscopy, Raman spectroscopy and optical emission spectroscopy. The deposition rates of diamond films were enhanced by adding argon into the methane-hydrogen system, but nondiamond carbon phases in the films also increased. It resulted from the increase of hydrocarbon radicals in the plasma. As oxygen was added, the quality of deposited diamond films was improved due to the decrease of C2 radicals and increase of OH radicals in the plasma. Simultaneous addition of 0.3% oxygen and 20% argon has been able to effectively suppress the formation of nondiamond carbon components and increase the deposition rate of diamond films. It appears that the ionized argon (Ar+) and excited argon atoms (Ar*) may activate the various chemical species and promote the reactions between the gas phase species and oxygen in the plasma. 相似文献
12.
Diamond nanowhiskers were fabricated by etching as-grown and aluminum coated diamond films in radio frequency (RF) Ar/O2 plasma. It was found that diamond nanowhiskers could be obtained by anisotropic etching of both kinds of films. For the as-grown diamond film, the whiskers randomly formed on the diamond surface with higher etching rate. However, for the Al-coated diamond film, an energy dispersive X-ray spectroscopy measurement revealed that the distribution of the whiskers was the same as that of the coated Al particles. During the etching process, Al particles served as masks contributing to restraining the etching of the film underneath. It was found that the distribution of the whiskers was significantly influenced by the Al coating. The whiskers (1 μm in height and 50 nm in diameter) could be obtained under the optimum etching condition. In addition, the dependence of the distribution of the whiskers on Al coating time was demonstrated. 相似文献
13.
L. Stafford W.T. Lim Ju-Il Song Young-Woo Heo Jeong-Joo Kim F. Schiettekatte 《Thin solid films》2008,516(10):2869-2873
Plasma etch damage to sputtered indium-zinc-oxide (IZO) layers in the form of changes in the film stoichiometry was investigated using Auger Electron Spectroscopy (AES). While damage resulting from pure chemical etching processes is usually constrained to the surface vicinity, ion-assisted chemical etching of IZO in Ar/CH4/H2 plasmas produces a Zn-rich layer, whose thickness (∼ 50 nm) is well-above the expected stopping range of Ar ions in IZO (∼ 1.5 nm). Based on AES depth profiles as a function of plasma exposure time, it is concluded that the observed Zn enrichment and In depletion deep into the IZO film are driven by the implantation of hydrogen atoms. 相似文献
14.
We investigated the growth characteristics of the nanocrystalline diamond films using CCl4/H2 as gas sources in a hot-filament chemical vapor deposition (CVD) reactor. Successful growth of nanocrystalline diamond at typical growth condition of 1.5-2.5% CCl4 and 550-730 °C substrate temperature has been demonstrated. Glancing angle X-ray diffraction (XRD) clearly indicated the formation of diamond in the films. Typical root-mean-square surface roughness of 10-15 nm and an optimal root-mean-square surface roughness of 6 nm have been achieved. Transmission electron microscopy (TEM) analyses indicated that nanocrystalline diamond film with an average grain size in the range of 10-20 nm was deposited from 2.5% CCl4/H2 at 610 °C. Effects of different source gas composition and substrate temperature on the grain nucleation and grain growth processes, whereby the grain size of the nanocrystalline film could be controlled, were discussed. 相似文献
15.
Abstract Diamond crystals have been successfully synthesized on (100) Si wafer using microwave plasma CVD. The growth was conditioned in a flowing system in which the parameters, such as CH4/H2 ratio, pressure, temperature and microwave power were varied. Cubo‐octahedra or tetrakaidecahedra are the equilibrium shape of diamond single crystals obtained under all conditions and are therefore the basic unit for the formation of polycrystalline diamond films, mostly through repetitive twinning and secondary growth of diamond crystals on {100} habit planes of cubo‐octahedra. Both X‐ray diffraction and Raman spectroscopy were used to facilitate the analysis of the diamond crystallinity and purity. These qualities are similar to those of natural diamonds. 相似文献
16.
In this paper, we report the investigation of the electrochemical properties of nano-structured diamond thin-film electrodes on porous silicon (PSi) synthesized by microwave plasma chemical vapor deposition (MPCVD). For the application, boron-doped and undoped diamond thin film has been performed and fabricated into an electrode device, and its microstructure, electrical and chemical properties have been studied. In order to enlarge the surface area of diamond electrodes, a negative bias was applied to the MPCVD process to deposit diamond thin film in a nano-structured form, so that its surface remained rough and nano-fine structured. Diamond thin films were analyzed by Raman spectroscopy and SEM. The morphology of boron-doped diamond thin films on PSi reveals nano-rods in the shape of diamond crystallites. Their electrochemical properties were evaluated by performing cyclic voltammetry (CV) measurement in inorganic K4[Fe(CN)6] in a K2HPO4 buffer solution. Boron-doped diamond thin film on PSi has demonstrated good electrochemical properties, with a larger redoxidation current of CV, due to its rough surface, which provides a more active electrochemical interface. 相似文献
17.
《Journal of Experimental Nanoscience》2013,8(4):555-564
Diamond nanorods (DNRs) synthesised by the high methane content in argon rich microwave plasma chemical vapour deposition (MPCVD) have been implanted with nitrogen ions. The nanorods were characterised by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The DNRs consist of single-crystalline diamond cores of 3–5?nm in diameter and several tens of nanometres in length. For purification from non-diamond contents, hydrogen plasma etching of DNRs was performed. Structural modifications of etched DNRs were studied after irradiating with 50?keV nitrogen ions under the fluence of 5?×?1014, 1?×?1015, 5?×?1015 and 1?×?1016?ions?cm?2. Nitrogen-ion implantation changes the carbon–carbon bonding and structural state of the nanocrystalline diamond (NCD). Raman spectroscopy was used to study the structure before and after ion irradiation, indicating the coexistence of diamond and graphite in the samples. The results indicated the increase in graphitic and sp2-related content, at the expense of decrease in diamond crystallinity, for ion implantation dose of 5?×?1015?cm?2 and higher. The method proves valuable for the formation of hybrid nanostructures with controlled fractions of sp3–sp2 bonding. 相似文献
18.
Deposition of hydrophobic nano-coatings with low-pressure radio frequency CH2F2/Ar plasma processing
In an attempt to perform hydrophobic nano-coating, this investigation examined various operational parameters including in RF plasma power, system gas pressure, and CH2F2:Ar ratio of low-pressure plasma processing. The low-pressure plasma, generated with radio frequency power at 13.56 MHz, was fed difluoromethane (CH2F2)/Ar gas mixture. The surface characteristics of the plasma polymerized films were studied by static contact angle measurement (CA) and atomic force microscopy (AFM). As a result, increasing deposition of CH2F2 plasma polymerized films was achieved in enhanced RF plasma power input. The CH2F2 plasma polymerized films also were conducted in a varying system gas pressure with enhanced hydrophobic surface property. The effects of CH2F2/Ar plasma on the surface characteristics of the plasma polymerized films were investigated as a function of the Ar content. The super hydrophobic coating under optimized operational parameters prepared in this study obtained water contact angles greater than 150°. It was found that the maximum water contact angles (161°) was obtained at 1.5:1 (CH2F2: Ar) ratio. In addition, AFM analysis shows that possible ion bombardment from CH2F2/Ar plasma can increase surface roughness, and effectively form a hydrophobic coating on the surface of heat sensitive materials. 相似文献
19.
In this study, we compared the line edge roughnesses (LER) and profile angles of chemical vapor deposited (CVD) amorphous carbon (a-C) patterns etched in an inductively coupled plasma (ICP) etcher produced by varying process parameters such as the N2 gas flow ratio, Q (N2), and dc self-bias voltage (Vdc) in O2/N2/Ar and H2/N2/Ar plasmas. The tendencies of the LER and profile angle values of the etched CVD a-C pattern were similar in both plasmas. The LER was smaller in the O2/N2/Ar than in the H2/N2/Ar plasmas, and the profile angle was larger in the O2/N2/Ar than in the H2/N2/Ar plasmas under the same processes conditions. The use of O2/N2/Ar plasma was more advantageous than the H2/N2/Ar plasma for controlling LER and profile angle. 相似文献
20.
D.Y. Kim 《Thin solid films》2008,516(11):3512-3516
Under certain conditions during ITO etching using CH4/H2/Ar inductively coupled plasmas, the etch rate selectivity of ITO to photoresist (PR) was infinitely high because the ITO films continued to be etched, but a net deposition of the α-C:H layer occurred on the top of the PR. Analyses of plasmas and etched ITO surfaces suggested that the continued consumption of the carbon and hydrogen in the deposited α-C:H layer by their chemical reaction with In and Sn atoms in the ITO resulting in the generation of volatile metal-organic etch products and by the ion-enhanced removal of the α-C:H layer presumably play important roles in determining the ITO etch rate and selectivity. 相似文献