Increasing N2 Flow Research Articles

Structural and electrical properties and current–voltage characteristics of nitrogen-doped diamond-like carbon films on Si substrates by plasma-enhanced chemical vapor deposition

We have deposited nitrogen-doped diamond-like carbon (N-DLC) films by plasma-enhanced chemical vapor deposition using CH4, N2, and Ar, and investigated the effects of N doping on the structure and the electrical, mechanical, and optical properties of the N-DLC films. We fabricated undoped DLC/p-type Si and N-DLC/p-type Si heterojunctions and examined the current–voltage characteristics of the heterojunctions. When the N2 flow ratio was increased from 0 to 3.64%, the resistivity markedly decreased from the order of 105 Ω·cm to that of 10−2 Ω·cm and the internal stress also decreased. The resistivity gradually increased with increasing N2 flow ratio from 3.64 to 13.6%, and then it decreased at a N2 flow ratio of 13.6%. These behaviors can be explained in terms of the clustering of sp2 carbons and the formation of sp3C–N, sp2C=N, sp1C≡N, and C–Hn bonds. The rectification ratio of the heterojunction using the N-DLC film prepared at 3.64% was 35.8 at ±0.5 V.

Effect of N2 flow rate on the properties of N doped TiO2 films deposited by DC coupled RF magnetron sputtering

N doped TiO2 films were deposited on glass substrates at room temperature using DC coupled RF magnetron sputtering with a TiO2 ceramic target. The influences of N2 flow rate on the deposition rate, crystal structure, chemical composition and band gap of the deposited films were investigated by Optical profiler, X-ray diffraction, X-ray photoelectron spectroscope and ultraviolet-visible spectrophotometer. The film growth rate gradually decreased with increasing N2 flow rate. As N2 flow rate increased, the crystallization of the films deteriorated, and the films tended to form amorphous structure. XPS analysis revealed that N dopant atoms were added at the substitutional sites into TiO2 lattice structure. FE-SEM results showed that the grain size of the film decreased and the crystallinity degraded as N2 flow rate increases. In addition, N doping caused an obvious red shift in the optical absorption edge.

Photoelectrochemical behavior of AlxIn1−xN thin films grown by plasma-assisted dual source reactive evaporation

In this work the dependence of photoelectrochemical (PEC) behavior of AlxIn1−xN (0.48 ≤x ≤ 0.66) thin films grown by plasma-assisted dual source reactive evaporation, on the plasma dynamics and the alloys properties was studied. The influence of nitrogen flow rate on the compositional, morphological, structural and optical properties of the as-prepared films were investigated using X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), micro Raman spectroscopy and UV–vis spectroscopy. The PEC study of the as-grown AlxIn1−xN thin films targeted for water splitting application were performed in the presence of simulated solar irradiation of AM 1.5G (100 mW/cm2). The PEC results revealed that the photocurrent for the AlxIn1−xN thin film grown at nitrogen flow rate of 80 sccm is ∼10-fold higher than the dark current. From the Mott–Schottky (MS) plots it was deduced that by increasing N2 flow rate up to 80 sccm, the flat band potential shifts toward more negative values. The good photoelectrochemical behavior of AlxIn1−xN thin films showed that this material could be a potential candidate for PEC water splitting.

Microstructure and wear properties of AISI M2 tool steel on RF plasma nitriding at different N2–H2 gas compositions

Wear behavior of quenched-tempered AISI M2 tool steel samples has been studied after plasma nitriding at different N2–H2 plasma gas flows containing 25, 50 and 75sccm N2. Plasma nitriding was performed at 450°C for 8h under floating potential using a plasma reactor equipped with a radio frequency power generator. Microstructure, phase composition, nitrided layer thickness, hardness and surface roughness of the samples were studied using optical microscopy, X-ray diffraction, microhardness and surface profilometry measurements. Dry sliding wear resistance of samples was determined by performing ball-on-disc wear testes. The results revealed formation of mainly a diffusion zone at the 25sccm N2–75sccm H2 gas flow and mono-phase ε-Fe2–3N compound layer at higher N2 concentrations. Plasma nitriding increases near surface hardness up to 50% (about 1600HV0.025) irrespective of the N2:H2 ratio, where nitrided layer depth and surface roughness increase with increasing the N2 flow rate in the plasma gas. Depending on the nitrogen content, sliding wear resistance may be improved between 20 and 90% with respect to the un-nitrided substrate. Among the nitrided samples the maximum and minimum wear resistance was obtained at plasma gases containing higher and lower H2 fractions, respectively. Decreasing wear resistance with increasing N2 flow rate in the plasma gas attributed to formation of the hard and brittle compound (white) layer on the sample surface and development of residual stress profiles.

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.

Study on the optical property and surface morphology of N doped TiO2 film deposited with different N2 flow rates by DCPMS

N doped TiO2 films were deposited by direct current pulse magnetron sputtering system at room temperature. By using UV-Vis spectrophotometer and atomic force microscope, we studied the influence of N2 flow rate on the optical property and surface morphology of films. The results indicate that the optical property and surface morphology of N doped TiO2 film was dominated by the N2 flow rate. The mean absorbency in visible range of pure TiO2 films is near to 0%, which means that the pure TiO2 could hardly display the photocatalytic property in visible range. When N2 flow rate is 2 sccm, the mean absorbency in visible range of N doped TiO2 film could reach at 24%. In this case, the film could be used as photocatalyst induced by visible light. While with increasing N2 flow rate, the mean absorbency in visible range of N doped TiO2 film decreased abruptly. Especially when N2 flow rate exceeded 8 sccm, the mean absorbency in visible range of N doped TiO2 film decreased to about 0%, which is like pure TiO2 fimls.

Nitrogen – Doped SnO<sub>2</sub> Thin Films Prepared by Direct Current Magnetron Sputtering

Nitrogen - doped tin oxide (N-doped SnO2) thin films were prepared on unheated glass substrate by dc magnetron sputtering of a Sn target in gas mixtures of O2 and N2. The N2 flow rates were varied from 0 to 15 SCCM with the same working pressure of 1×10-2 Torr. The as-deposited films were annealed in vacuum at 400 °C for 1 h. The films structure, electrical properties and optical properties were characterized by X-ray diffraction (XRD), 4-point probe and Hall effect measurement and portable fiber optic UV-vis spectrometer, respectively. The observed XRD patterns of films showed preferred (101) orientation of the SnO2 tetragonal structure. The average crystalline size of the (101) diffraction peak decreased from 5.10 to 4.07 nm with N2 flow rate increased. Hall measurement indicated that resistivity increased and carrier concentrations decreased as N2 flow rate increased. The carrier concentrations decreased because N atoms substituted oxygen atom in SnO2 lattice. The N atoms may forms acceptor level in SnO2 band gap resulting in hole generation. The electron concentration from intrinsic defect were neutralized with the hole concentration. The carrier concentration decreased from 3.42×1017 cm-3 for un-doped SnO2 to the order of 1014 cm-3. The average percent transmittance of un-doped SnO2 of about 77.5% in visible range (400-700 nm) decreased to 60% with increasing N2 flow rate. The optical band gap decreased from 3.64 eV for un-doped SnO2 to 3.45 eV for N-doped SnO2 films.

Effect of Nitrogen Partial Pressure on Reactive Magnetron Sputtering From Ti13Cu87 Metalloid Target: Simulation of Chemical Composition

A sintered Ti13Cu87 composite target was reactively sputtered in Ar–N2 gas mixtures, and sputtered species were deposited on Si (111) substrates. We study the pressure-dependent target mode variation of the Ti13Cu87–N2 system, by measuring the N2 partial pressure, deposition rate, target voltage, and Ti and Cu concentrations for various reactive N2 gas flow ratios. The Ti13Cu87 target surface begins to be nitrided with increasing N2 flow ratio, which is caused by the absorption and the implantation of N2 gas on the Ti13Cu87 target surface. Hence, the deposition rate was reduced due to the lower sputtering yield and a higher scattering under the mass transport between the target-substrate spacing. Secondary electron emission yield of the nitride portion of targetsurface is higher than that of the unnitrided portion. Therefore, at a constant sputtering power, the target voltage decreases, as the N2 partial pressure increases. By means of the TRIM.SP Monte-Carlo simulation, the particle reflection coefficients of reflected neutrals was calculated. The initial energies of reflected neutrals and the sputtered particles at the substrate were estimated using the simple binary collision model and the distribution-weighted averages, respectively. Their final energies depend on the energy dissipation during the mass transport through the gas phase. The energy and angular characteristics of the sputtering yield were extracted from the available literature to obtain a prediction about a final composition of films.

Optical and Electrical Properties of Nitrogen-Doped Diamond-Like Carbon Films Prepared by a Bipolar-Type Plasma-Based Ion Implantation

Diamond-like carbon (DLC) films are prepared by a bipolar-type plasma-based ion implantation (PBII) technique using toluene and nitrogen gases (N2), and the optical and electrical properties are examined as a function of N2 flow rate. The N concentration in the films and structural changes are also examined by Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM), and Raman spectroscopy. It is found that the deposition rate decreases, but N concentration linearly increases with increasing N2 flow rate. Granular surfaces are observed and the grains decreases in size as N2 flow rate increases. In addition, Raman analysis suggests that aromatic ring clusters and the amorphous structure increase in amount. The optical band gap and conductivity increase with increasing N concentration up to about 11 at. %, and then decrease with further increase in N concentration.

Ru/WNx Bilayers as Diffusion Barriers for Cu Interconnects

Bilayers of Ru (7 nm)/WNx (8 nm) prepared by sputtering were investigated as diffusion barriers between Cu and Si, and their performances were compared as a function of N2 flow rate during the deposition of WNx. The Ru/WNx bilayer diffusion barriers were stable upon annealing at up to at least 650 °C for 30 min while a Ru single layer (15 nm in thickness) failed after annealing at 450 °C owing to the formation of Cu silicide. Grazing-angle X-ray diffractometry results showed that the crystallinity of the WNx film was degraded but that its nanocrystalline state preserved upon annealing at higher temperatures with increasing N2 flow rate during the deposition. These resulted in the better performance against Cu attack of bilayer diffusion barriers with the WNx film prepared with a higher N2 flow rate.

Atomic Layer Deposition of Co Using N2/H2 Plasma as a Reactant

Cobalt thin films were deposited by plasma-enhanced atomic layer deposition (PE-ALD) using CoCp2 as a precursor and N2/H2 plasma as a reactant. We systematically investigated the changes in Co film properties depending on N2/H2 gas flow ratio to study the role of N during PE-ALD Co. With increasing N2 flow ratio, the resistivity decreased reaching minimum value at fN2/H2 = 0.25 ∼ 0.33, which corresponds to the atomic ratio in NH3 molecule, and then increased. With only N2 or H2 plasma, films with very high sheet resistance over 1 M/sq were deposited. The chemical compositions of Co films were analyzed by x-ray photoelectron spectroscopy (XPS) and thickness and conformality were determined by x-ray reflectometry (XRR) and field emission scanning electron microscopy (FE-SEM), respectively. Then, the silicidation of PE-ALD Co films producing epitaxial CoSi2 were investigated by x-ray diffraction (XRD) and high-resolution cross-sectional transmission electron microscopy (HR-XTEM).

Effect of N2 Gas Flow Ratio in Plasma-Enhanced Chemical Vapor Deposition with SiH4–NH3–N2–He Gas Mixture on Stress Relaxation of Silicon Nitride

The effects of N2 gas flow ratios in silicon nitride deposition with SiH4–NH3–N2–He gas mixtures at a temperature of 275 °C on stress relaxation have been investigated. We have demonstrated that film stress can be controlled in the range from -692 MPa (compression) to 170 MPa (tension) by increasing N2 gas flow ratio. From the evaluation of the composition ratio of N/Si, film density, and bonding structure, the relationships between film stress and these properties are investigated. The amount of nitrogen incorporated into the film as N–H bonds increased with increasing N2 flow ratio, resulting in a higher composition ratio of N/Si. At a higher N2 gas flow ratio, excess N2 gas in the plasma may disturb the ion bombardment of ionized species on the film surface, resulting in a decrease in the film density. The higher N2 gas flow ratio leads to the generation of a Si–N bonding structure with a larger bond angle at the nitrogen atom site due to bond-strain relaxation, leading to a higher frequency of Si–N stretching vibration. Therefore, a nitrogen-richer SiN film with many N–H bonds and a lower film density exhibits bonding structures with a lower bond strain, leading to the relief of film stress.

Characteristics of Silicon Oxynitride Barrier Films Grown on Poly(ethylene naphthalate) by Ion-Beam-Assisted Deposition

For the application of transparent barriers to water vapor permeation for plastic substrates, we have prepared silicon oxynitride thin films on a poly(ethylene naphthalate) substrate at room temperature by the ion-beam-assisted electron beam evaporation method and investigated their characteristics with respect to N2 flow rate in the ion source. The experimental results reveal that when N2 flow rate increases, the nitrogen concentration and Si–N bonding in SiOxNy films increase owing to the assisted N2 ion incorporations during the film deposition process. Also, with increasing N2 flow rate, the surface roughness and optical transmittance of the barrier film decrease, whereas refractive index and film density increase. It is confirmed that the water vapor transmission rate of our barrier films decreases with the incorporation of N2 ions into the films, being strongly dependent on surface roughness and film density.

Inductively Coupled Plasma Etching of Chemical-Vapor-Deposited Amorphous Carbon in N2/O2/Ar Chemistries

In this study, we investigated the etching characteristics and mechanism of an amorphous carbon (a-C) layer for a multi-level resist (MLR) structure. Chemical-vapor-deposited (CVD) a-C layers with a SiO2 hard-mask were etched in an inductively coupled plasma (ICP) etcher by varying the process parameters such as top electrode power, bottom electrode power, and gas flow ratio in N2/O2/Ar plasmas. The etch rate and profile angle of the CVD a-C thin films were decreased with increasing N2 flow ratio in the N2/O2/Ar plasmas. As the N2 flow ratio increased, the etch rate and the profile angle were reduced due to the enhanced formation of CNx on the etched surface. The etch rate of the CVD a-C thin films was increased with increasing the top and bottom electrode powers.

Influence of deposition parameter on chemical structure and moisture resistant properties for SiNx films deposited by DC pulse magnetron sputtering

Hydrogen-free SiNx films were deposited by direct current pulse magnetron sputtering at room temperature. We have studied the influence of N2 flow rate and Si target sputtering power on the structural characteristics and properties of deposited films by using Fourier-transform infrared spectroscopy，auto water vapor permeability tester，ultraviolet-visible spectrophotometer，stylus profilometer，and contact angle measurement. The results indicate that the content of Si—O bonding in SiNx films increaseds and moisture resistant property of SiNx films decreases with increasing N2 flow rate or decreasing Si target sputtering power. The films deposited at 300W of Si sputtering power and 6sccm of N2 flow rate show excellent water vapor permeability (0.764) with transmittance higher than 97.5% in visible range.

Grain boundary scattering for temperature coefficient of resistance (TCR) behaviour of Ta–Si–N thin films

In this study, we have investigated the electrical properties of TaxSiyNz thin films deposited by reactive co-sputtering at different nitrogen flow ratios. The electrical resistivity and temperature coefficient of resistance (TCR) were measured by an I–V measurement system including the four-point probe from 30 to 100 °C. The results indicated that the electrical resistivity decreased with increasing temperature, i.e. negative TCR, in each film prepared at different N2 flow ratios. The phase formation of a Ta–Si–N film at different N2 flow ratios (5–30%), as well as the change in microstructure from a symmetric broad peak to an asymmetric peak, was studied by a grazing incident x-ray diffractometer. In view of the fact that the grain size increases with increasing N2 flow ratio, it would be expected that increasing resistivity and magnitude of negative TCR with increasing grain size nature may be due to scattering of electrons by the grain boundaries. It is probable that coarse grained material of Ta–Si–N with amorphous-like microstructure has a higher electrical resistivity due to the high ratio of the grain boundary area and increase in non-metallic amorphous SiNx. The electrical properties of these films are also discussed by the grain boundary scattering model.

Etching characteristics and application of physical-vapor-deposited amorphous carbon for multilevel resist

For the fabrication of a multilevel resist (MLR) based on a very thin, physical-vapor-deposited (PVD) amorphous carbon (a-C) layer, the etching characteristics of the PVD a-C layer with a SiOx hard mask were investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in O2∕N2∕Ar plasmas: high-frequency/low-frequency combination (fHF∕fLF), HF/LF power ratio (PHF∕PLF), and O2 and N2 flow rates. The very thin nature of the a-C layer helps to keep the aspect ratio of the etched features low. The etch rate of the PVD a-C layer increased with decreasing fHF∕fLF combination and increasing PLF and was initially increased but then decreased with increasing N2 flow rate in O2∕N2∕Ar plasmas. The application of a 30nm PVD a-C layer in the MLR structure of ArF PR∕BARC∕SiOx∕PVD a-C∕TEOS oxide supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the TEOS-oxide layer.

The influence of N2 flow rate and substrate temperature on Ti1‐xAlxN thin films

AbstractTitanium aluminium nitride (Ti1‐xAlxN) films have been deposited on silicon (111) substrate at a N2 flow rate of 2 sccm and 20 sccm and at a substrate temperature of 773 K and at a N2 flow rate of 2 sccm and at a substrate temperature of 873 K by reactive DC magnetron sputtering technique. The effect of N2 flow rate and substrate temperature on the grain size and surface roughness of the deposited films have been investigated. The films have been analysed by X‐ray diffraction (XRD) and atomic force microscopy (AFM). The films were found to be nanocrystalline. While the grain size of the films decreases with increasing N2 flow rate and decreases with increasing substrate temperature, the surface roughness of the films decreases with increasing N2 flow rate and increases with increasing temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Bonding configurations and photoluminescence of amorphous Si nanoparticles in SiNx films

The Si-in-SiNx:H films were prepared by helicon wave plasma chemical vapor deposition technique with active gas N2/SiH4/H2, and the tuning photoluminescence of the films from red to blue-green is achieved by changing the N2 flow rate. The analysis of Fourier transform infrared spectroscopy and ultraviolet-visible absorption demonstrate that the deposited films have higher hydrogen contents. Increasing of N2 flow rate makes the hydrogen bonding configurations change and the size of amorphous silicon particles decrease, to which corresponds the increase of band gap and also the decrease of the microstructure order. The tuning photoluminescence is mainly related to the quantum confinement of amorphous silicon particles. The broadening of the spectral widths of main photoluminescence and the enhancement of their intensities are obtained for the films deposited with increasing N2 flow rates.

Influence of nitrogen flow rate on growth of TiAlN films prepared by DC magnetron sputtering

Thin films of TiAlN were deposited on (111) oriented silicon single crystal substrates from a composite Ti–Al target by DC reactive magnetron sputtering at 773 K under various N2 flow rates. Substantial influence of N2 flow rate on the rate of deposition, grain size, crystallinity, composition, hardness and resistivity was observed. While the deposition rate, grain size and the ratio of concentration of Ti to Al of the deposited TiAlN films decreased with increasing N2 flow rate, the resistivity of the films increased with increasing N2 flow rate.