Electron Cyclotron Resonance Chemical Vapor Deposition Research Articles

Improving the tribological properties of DLC (Fullerene-like) films grown by ECR-CVD with metal nanoparticles incorporation

ABSTRACTThin Me-DLC films with different metal contents have been deposited by ECR-CVD (Electron Cyclotron Resonance Chemical Vapour Deposition). Before the growth process, metal nanoparticles were scattered over the substrate surface by dipping it into a dispersion previously sonicated. The concentration of the dispersion (150, 300, 500 and 5000 ppm) controls the metal content into the carbon coating. The morphology of the deposited samples was analysed by SEM (Scanning Electron Microscopy). The metal content in the carbon films has been evaluated by SIMS (Secondary Ion Mass Spectroscopy). The incorporation of low amounts of metal nanoparticles into the hard carbon coating produces an outstanding improvement in the durability of the layer, as detected by pin-on-disc tests. For an optimum chromium content of 300 ppm of nanoparticles in the dispersion, the grown layer exhibits a noteworthy higher wear resistance respect to that of the DLC reference film. More precisely, in this case, the Cr-DLC coating undergoes ten times longer wear process than the reference DLC coating. However, it is important to indicate that in samples grown using more concentrated dispersions (> 300 ppm), a rapid deterioration of the coating is produced and short lifetimes have been detected, attributed to the large contribution of metal to the transfer layer.

Mass Density as Basis Parameter on Mechanical Properties under Diamond-Like Carbon Prepared in Wide Range of Conditions Using Variety of Methods

Diamond-like carbon (DLC) films were prepared on steel substrates by eleven suppliers using different types of equipment utilized in each company's own coating formation process. The deposition methods include sputtering, electron cyclotron resonance chemical vapor deposition (ECR-CVD), plasma enhanced chemical vapor deposition (PECVD), arc ion plating (Arc), filtered arc deposition (FAD), and plasma-based ion implantation (PBII). Some correlation of mechanical properties seems to be valid in a narrow range of parameters produced by a particular deposition method. In order to investigate general correlations in a wide range of parameters, various DLC films were prepared by different suppliers on the same substrate, and were evaluated in exactly the same manner. Independent of deposition methods, there existed correlations of the hardness, elastic modulus and Raman shift with a wide range of mass density.

HYDROGENATED AMORPHOUS/NANOCRYSTALLINE SILICON THIN FILMS ON POROUS ANODIC ALUMINA SUBSTRATE

Hydrogenated amorphous and nanocrystalline silicon thin films were grown on porous anodic alumina substrates using electron cyclotron resonance-chemical vapor deposition technique from argon, hydrogen and silane gas composition. The structural characterization of the deposited hydrogenated silicon films were performed by scanning electron microscopy, Raman spectroscopy, and X-ray diffraction studies. The results revealed that mixed amorphous/nanocrystalline silicon phases with specific novel morphology were obtained on textured surfaces. The evolution of the film on ripple-like surface exhibited amorphous dominant structure, however, the film deposited on tipped/ribbed surface consisted of amorphous and nanocrystalline phases composite. The growth process strongly depends on the textured substrate pattern, which influences on the nanostructure shapes and crystallinity.

Tribological study of hydrogenated amorphous carbon films with tailored microstructure and composition produced by bias-enhanced plasma chemical vapour deposition

We investigated the mechanical and tribological properties of hydrogenated amorphous carbon (a-C:H) films on silicon substrates by nanoindentation, ball-on-disc tribotesting and scratch testing. The a-C:H films were deposited from an argon/methane gas mixture by bias-enhanced electron cyclotron resonance chemical vapour deposition (ECR-CVD). We found that substrate biasing directly influences the hardness, friction and wear resistance of the a-C:H films. An abrupt change in these properties is observed at a substrate bias of about −100 V, which is attributed to the bias-controlled transition from polymer- to fullerenelike carbon coatings. Friction coefficients in the range of 0.28–0.39 and wear rates of about 7 × 10 − 5 mm 3/Nm are derived for the polymeric films when tested against WC–Co balls at atmospheric test conditions. On the other hand, the fullerenelike hydrogenated carbon films produced at ion energies > 100 eV display a nanohardness of about 17 GPa, a strong reduction in the friction coefficient (∼ 0.10) and a severe increase in the wear resistance (∼ 1 × 10 − 7 mm 3/Nm). For these films, relative humidity has a detrimental effect on friction but no correlation with the wear rate was found.

Rapid Thermal Annealing of Amorphous Silicon Thin Films Grown by Electron Cyclotron Resonance Chemical Vapor Deposition

AbstractHydrogenated amorphous silicon (a-Si:H) thin films were deposited on pre-oxidized Si wafers by electron cyclotron resonance chemical vapor deposition (ECRCVD). The rapid thermal annealing (RTA) treatments were applied to the as-grown samples in nitrogen atmosphere, and the temperature range for the RTA process is from 450 to 950 °C. The crystallization and grain growth behaviors of the annealed films were investigated by Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The onset temperature for the crystallization and grain growth is around 625 ∼ 650°C. The crystalline fraction of annealed a-Si:H films can reach ∼80%, and a grain size up to 17 nm could be obtained from the RTA treatment at 700 °C. We found that the crystallization continues when the grain growth has stopped.

P-MNS-01 EVALUATION OF NANOMETER SCALE MECHANICAL PROPERTIES OF EXTREMELY THIN DIAMOND-LIKE CARBON (DLC) FILMS(Micro/Nanosystem Science and Technology,Technical Program of Poster Session)

Nanometer scale mechanical properties of extremely thin DLC films deposited by filtered cathodic vacuum arc (FCVA) and electron cyclotron resonance chemical vapor deposition (ECR-CVD) methods were evaluated. DLC films, whose target thicknesses are 100nm, 5nm, and 2nm were, deposited on Si (100) substrates by FCVA and ECR-CVD method. Nanoindentation hardness and nanowear resistance of these DLC films are investigated by AFM (Atomic force microscopy). Nanoindentation hardness of 100-nm-thick DLC films deposited by FCVA and ECR-CVD is 57GPa and 25GPa, respectively. The nanowear resistance of 5nm- or 2nm-thick DLC films can be evaluated by AFM at proper load conditions. Then nanowear test reveal the excellent wear resistance of the FCVA-DLC films.

X-ray reflectivity studies on DLC films deposited by microwave ECR CVD: Effect of substrate bias

Diamond like carbon (DLC) films were deposited at room temperature on Si (111) substrates by microwave electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) process using plasma of methane diluted with argon gas. During deposition, dc self bias (− 25 V to − 200 V) on substrate was varied by application of RF power to the substrate. The influence of substrate bias on density of the deposited films was studied by X-ray reflectivity (XRR). The results from these measurements are further correlated with the results from UV and visible Raman spectroscopy. DLC film is modeled as a structure having three different layers such as low density surface, bulk and interface with the substrate. This three-layer model is used to fit the measured XRR data to evaluate the surface, interface and interlayer roughness, thickness and density of these films. The surface roughness obtained from XRR is correlated with the results from Atomic Force Microscopy (AFM) measurements. The observed results are explained based on the subplantation model for DLC film growth.

Bird's Beak and Thermally Induced Stress Defects Evaluations of LOCOS Structures Fabricated Using ECR-CVD SiNx Without Pad Oxide

Silicon Nitrides were deposited on the silicon substrates by ECR-CVD (electron cyclotron resonance chemical vapor deposition), without using the pad oxide in LOCOS (LOCal Oxidation of Silicon) isolation technology. The SiNx/Si structure was used to substitute the SiNx/SiO2/Si. The study of this type of the structure was motivated by the possibility to reduce the length of the bird's beak. Defects were created on silicon because the high temperature (1000ºC) applied on SiNx/Si. The Dash wet chemical etch was used to etch the defect on silicon. Optical and SEM microscopy analysis were used to investigate the bird's beak in the obtained LOCOS structures and the defects (dislocations) on silicon performed after high temperature process.

Structural characteristics of carbon nanostructures synthesized by ECR-CVD

In this study, carbon nanotubes (CNTs) and nanoparticles were synthesized by an electron cyclotron resonance-chemical vapor deposition (ECR-CVD) system. Results show that both high- and low-aspect-ratio CNTs and nanoparticles are found. The CNTs range in length from tens of nanometers to micrometers, and in outer diameter from about 5 to 50nm. Transmission electron microscope (TEM) images show that the faceted nanoparticles exhibit polyhedral or onion or irregularly profiled fullerene structures, and the CNTs growth is from the interlayers lamination. The surface sheet resistance and average surface roughness of the CNT films are about 360Ω per square and 7–17nm, respectively. When the CNT sample has a higher amount of nanoparticles, the current density will be increased.

Surface passivation of InGaP/GaAs HBT using silicon-nitride film deposited by ECR–CVD plasma

In this paper we have developed a passivation technique with silicon-nitride (SiN X ) film that requires no surface pre-treatment, and is fully compatible to monolithic microwave integrated circuits (MMICs). The nitride depositions were carried out by ECR–CVD (electron cyclotron resonance–chemical vapor deposition) directly over InGaP/GaAs heterojunction structures, which are used for heterojunction bipolar transistors (HBTs). Optical emission spectrometry (OES) was used for plasma characterization, and low formation of H and NH molecules in the gas phase was detected at pressure of 2.5 mTorr. These molecules can degrade III–V semiconductor surfaces due to the preferential loss of As or P and hydrogen incorporation at the substrate. The substrates were cleaned with organic solvents using a Sox-let distillate. The ECR depositions were carried out at a fixed substrate temperature of 20 °C, SiH 4/N 2 flow ratio of 1, Ar flow of 5 sccm pressure of 2.5 mTorr and microwave (2.45 GHz) power of 250 W and RF (13.56 MHz) power of 4 W. We have applied this film for InGaP/GaAs HBT fabrication process with excellent results, where two major contribuiton is related to this passivation technique, the enhancement in the transistor dc gain β and the improvement in the signal-to-noise ratio when compared unpassivated and passivated devices.

P‐103: Anodic‐Aluminum‐Oxide Templated Carbon Nanotubes in the Field Emission Triode

AbstractTo fabricate the field‐emission triode structure, carbon nanotubes (CNT) were used as field emitters and grown in the anodic aluminum oxide (AAO). AAO thin layer with vertical pore channels was first prepared on the Si (100) substrate and was used to template the following growth of CNTs in an electron cyclotron resonance chemical vapor deposition (ECR‐CVD) system. The tetraethoxysilane (TEOS) oxide and Al layer were deposited on the CNTs and acted as the dielectric layer and gate electrode layers for the triode structure, respectively. Reactive ion and wet etches were then used to open the field‐emission area in the triode. Field‐emission characteristics of the CNT emitters have been studied and an anode turn‐on field of ∼ 8.05 V/μm was measured.

Effects of gas composition on the growth of multi-walled carbon nanotube

This paper studies the effects of different gas compositions on the growth of multi-walled carbon nanotube (MWCNT) films by using an electron cyclotron resonance chemical vapor deposition (ECR-CVD) method. The Raman spectrum was employed to explore the composition of the MWCNT films grown under different mixtures of C 3H 8 and H 2. The results showed that the optimum relative intensity ratio of the D band to G band (i.e., I D/ I G) is 2 for the cases considered in this study. In addition, the morphology and microstructure of the MWCNTs were examined by field emission scanning electron microscopy (FE-SEM) and field emission gun transmission electron microscopy (FEG-TEM). Furthermore, atomic force microscopy (AFM) and scanning thermal microscopy (SThM) were used to study the surface topography and thermal properties of the MWCNTs.

DC substrate bias effects on the physical properties of hydrogenated amorphous carbon films grown by plasma-assisted chemical vapour deposition

Hydrogenated amorphous carbon (a-C:H) films have been grown from argon/methane gas mixtures by electron cyclotron resonance chemical vapour deposition (ECR-CVD) on silicon substrates. The effects of the application of a DC substrate bias on the structural, morphological and mechanical properties of the films have been explored by multiple analysis techniques such as infrared and micro-Raman spectroscopy, atomic force microscopy, nanoindentation and pin-on-disk wear testing. In general, within the range of applied substrate bias (i.e. from −300 up to +100 V) we have observed a strong correlation between all measured properties of the a-C:H films and the ion energy. This work shows that the properties can differ greatly and indicates a threshold energy in the order of 90 eV. For the production of hard, low-friction coatings energies above this value are required.

Influence of external bias on the surface morphology of a-C:H films grown by electron cyclotron resonance chemical vapor deposition

We have studied the influence of an external bias on the surface morphology of a-C:H films grown by electron cyclotron resonance chemical vapor deposition (ECR-CVD) on silicon substrates. We have deposited films for 1 h at different bias from + 100 V down to − 250 V and analyzed their surface morphology by atomic force microscopy (AFM). For biases equal or higher than − 80 V the film morphology is cauliflower-like, which is due to the shadowing geometry effects inherent to the deposition process. In contrast, for highly negative biases the films become ultrasmooth. Here, the film morphology is consistent with an Edwards–Wilkinson scaling behavior, which starts to operate at shorter length distances as the external bias becomes more negative. This morphology is likely due to the interplay of ion induced physical sputtering and enhanced downhill surface mobility.

Growth of carbon nanotube field emitters in the triode structure using anodic aluminum oxide as the template

Carbon nanotubes (CNT) were grown in anodic aluminum oxide (AAO) and used as field emitters in a triode structure. To fabricate the field-emission triode structure, nanoporous anodic aluminum oxide (AAO) thin layer was first prepared on the Si(100) substrate, followed by the growth of vertically aligned carbon nanotubes in AAO pore channels by electron cyclotron resonance chemical vapor deposition (ECR-CVD). The SiO 2 dielectric and Al gate electrode layers required for the triode structure were directly deposited on the CNTs. Reactive ion and wet etches were then used to open the field-emission area in the triode. Scanning electron microscopy and Raman spectroscopy studies revealed that damage to CNT emitters in the etched area was trivial. Field-emission characteristics of the CNT emitters have been studied and an anode turn-on electric field of ∼ 8.05 V/μm was measured.

Effect of O2-doping on bonding configuration and electric properties of SiCOH films prepared by decamethylcyclopentasiloxane electron cyclotron resonance plasma

Carbon-doping oxide materials (SiCOH films) with k of 2.62 are prepared by electron cyclotron resonance chemical vapor deposition (ECR-CVD) from the mixture of decamethylcyclopentasioxane (D5) and oxygen (O2). This paper investigates the effect of O2-doping on bonding configuration, dielectric property and leakage current of the SiCOH low dielectric constant films. The results show that the leakage current can be reduced obviously on the premise that dielectric constant k is kept at a lower value by small O2-doping amount. For the SiCOH film deposited under O2 flow of 3 cm3/min, the dielectric constant k as low as 2.62 and leakage current of 8.2×10-9 A/cm2 can be obtained.

Large-grained polycrystalline silicon films on glass by argon-assisted ECRCVD epitaxial thickening of seed layers

This work reports on the low temperature ( ⩽ 550 ∘ C ) epitaxial growth of Si films on polycrystalline seed layers made by aluminium-induced crystallisation (AIC) on glass. The seed layers were chemically mechanically polished before use and electron–cyclotron resonance chemical vapour deposition (ECRCVD) was used to deposit the Si films. The quality of the deposited films depends strongly on the addition of Ar to the hydrogen rich silane growth environment. With Ar, epitaxial growth has been achieved to a thickness of ∼ 2.7 μ m . Electron backscatter diffraction (EBSD) analysis shows a similar grain structure to the starting seed layers with a preferred (1 0 0) orientation and grain sizes approaching ∼ 10 μ m for samples up to ∼ 1.7 μ m thick. Thicker films ( 2.7 μ m ) show a more mixed orientation with an increase in the density of smaller grains. Nevertheless, more than 95% of the film surface can be indexed suggesting large grained crystal growth has occurred on all grain orientations present in the seed layer. Similar behaviour is also exhibited by the films grown without Ar but these films are more defective and the deterioration in the EBSD orientation maps occurs at a significantly lower thickness. The role of Ar in the growth process is briefly discussed.

Diamond-like carbon films deposited by a hybrid ECRCVD system

A novel hybrid technique for diamond-like carbon (DLC) film deposition has been developed. This technique combines the electron cyclotron resonance chemical vapor deposition (ECRCVD) of C 2H 2 and metallic magnetron sputtering. Here we described how DLC film is used for a variety of applications such as stamper, PCB micro-tools, and threading form-tools by taking advantage of hybrid ECRCVD system. The structure of the DLC films is delineated by a function of bias voltages by Raman spectroscopy. This function includes parameters such as dependence of G peak positions and the intensity ratio ( I D/ I G). Atomic force microscope (AFM) examines the root-mean-square (R.M.S.) roughness and the surface morphology. Excellent adhesion and lower friction coefficients of a DLC film were also assessed.

Electrical Properties of Plasma Deposited Low-Dielectric-Constant Fluorinated Amorphous Carbon Films

Fluorinated amorphous carbon (a-C:F) films were deposited at room temperature using C4F8 and CH4 as precursor gases by electron cyclotron resonance chemical vapour deposition (ECR-CVD). Chemical structures were analysed using X-ray photoelectron spectroscopy (XPS). The current conduction shows ohmic behaviour and the leakage current increases with the content of C sp2 in the deposited a-C:F films at a low electric field. The behaviour of the leakage current is well explained by the Poole-Frankel mechanism at a high electric field. The interface traps, rather than chemical structures, of a-C:F films determine the PF emission current.

Influence of the gas composition on the synthesis of boron-doped carbon nanotubes by ECR-CVD

Boron-doped carbon nanotubes (CNTs) were synthesized on porous silicon by electron cyclotron resonance chemical vapor deposition (ECR-CVD). CH 4, B 2H 6 and H 2 were used as the source gases and Fe 3O 4 nanoparticles as the catalyst. The effect of gas composition on the boron-doped CNTs growth characteristic was investigated. Scanning electron microscopy , transmission electron microscopy and X-ray photoelectron spectroscopy were used to evaluate the structure and composition. The results show that adding B 2H 6 influences the growth characteristic of CNTs greatly. CNTs tend to unaligned growth with boron. The increase of the B 2H 6 ratio leads to changes in the structure of CNTs from straight tubular to bamboo-like and makes the outer diameters bigger, the tube walls thicker, cause a rough surface and a decrease in the growth rate of the CNTs. An increase in the B/C ratio within the samples was detected as the B 2H 6 ratio in the precursor gas was increased.