Kei-ichi Namiki

Deposition of Mechanically Hard Amorphous Carbon Nitride Films with High [N]/([N]+[C]) Ratio

Mechanically hard amorphous carbon nitride films were prepared by a combination of radio frequency (RF) bias voltage applied to a substrate and chemical vapor deposition using a decomposition reaction of BrCN with a microwave discharge flow of Ar. A pulsed operation of the negative RF bias voltage (-VRF) was applied to avoid excess sputtering of the film. The [N]/([N]+[C]) ratios of the films were ≈0.5 irrespective of the application of -VRF. The maximum hardness was 36±10 GPa for the film obtained under the conditions of -VRF=100 V, a pulse period of 1000 s, and a pulse-on time of 800 s. According to the IR spectra, the intensity of the stretching vibration of the C–N bond was increased by the application of -VRF. The Raman spectra showed increases in the relative intensity and width of the D-band. From these observations, the mechanism of film hardening when -VRF is applied was discussed.

Hydrogenated-amorphous carbon nitride films formed from the dissociative excitation reaction of CH3CN with the microwave-discharge flow of Ar: Correlation of the [N]/([N]+[C]) ratio with the relative number densities of the CH(A2Δ) and CN(B2Σ+) states

High-resolution optical emission spectra of the CN(B2Σ+–X2Σ+) and CH(A2Δ–X2Π) transitions were observed in the dissociative excitation reaction of CH3CN with the microwave-discharge flow of Ar. The H2O molecules contained in the starting materials and/or adsorbed on the wall of the apparatus were removed by using P2O5 as a desiccant. The pressure of Ar, PAr, was in the range of 0.1–0.8 Torr. From the simulation analysis of the observed spectra, the ratio of the concentrations of the CH(A2Δ) and CN(B2Σ+) states, NCH(A)/NCN(B), was determined as 0.09–0.41. It was indicated that the CN(B2Σ+) state was formed via the ion–electron recombination as well as the energy transfer from the metastable state of Ar. Based on the correlation between the NCH(A)/NCN(B) and [N]/([N]+[C]) ratios reported in the system without desiccation [Jpn. J. Appl. Phys. 40, 332 (2001)], the [N]/([N]+[C]) ratio in the desiccated system was predicted to be ≈0.18. The hydrogenated-amorphous carbon nitride films prepared under the conditio...

Absolute density and sticking probability of the CN(X2Σ+) radicals produced by the dissociative excitation reaction of BrCN with the microwave discharge flow of Ar

The 4-0, 5-1, and 7-2 bands of the A2Πi–X2Σ+ transition of the CN radical produced by the dissociative excitation reaction of BrCN with the microwave discharge flow of Ar were observed by laser induced fluorescence (LIF) spectroscopy. The intensity of the LIF spectrum of the individual transition was evaluated by a spectral simulation analysis, and converted to the absolute value by calibrating against Rayleigh scattering by Ar atoms. The effective lifetime of the A2Πi state was measured to be 2.2(5) µs. The absolute number density of the CN(X2Σ+) radicals in the observation region of LIF was evaluated to be 1.5(3)×1020 m-3. Based on this value, the pumping speed, and the amount of a-CNx:H film deposited, the sticking probability of the CN radicals onto the a-CNx:H films was estimated to be 0.01.

Mechanism of Formation of the CN(B2Σ+) State from Dissociative Excitation Reaction of BrCN with Electron Cyclotron Resonance Plasma of Ar

High-resolution emission spectra of the CN(B2Σ+–X2Σ+) transition and the resonance lines of Ar and Ar+ have been observed for the dissociative excitation reaction of BrCN with the electron cyclotron resonance (ECR) plasma of Ar. These spectra have been compared with those observed for the reaction with the microwave (MW) discharge flow of Ar. It is found that the energy transfer from the metastable state of Ar which proceeds predominantly in the MW discharge flow does not proceed in the ECR plasma. The electron density and temperature have been measured by an electrostatic-probe measurement, from which the kinetic analysis of formation of CN(B2Σ+) has been conducted. The most dominant process of formation of the CN(B2Σ+) state in the ECR plasma is considered to be the dissociative excitation of BrCN by the impact of high-energy free electrons, where the contribution of the recombination of BrCN+ with thermal free electrons cannot be excluded.

Dissociative Excitation Reaction of CH3CN with the Discharge Flow of Ar: Prediction of the [N]/([N]+[C]) Ratio of Hydrogenated Amorphous Carbon Nitride Films in the Desiccated System

Emission spectra of the CN(B2Σ+–X2Σ+) and CH(A2Δ–X2Π) transitions were observed in the dissociative excitation reaction of CH3CN with the microwave-discharge flow of Ar. The H2O molecules contained in the starting materials and adsorbed on the wall of the apparatus were removed by using P2O5 as a desiccant. The pressure of Ar, PAr, was in the range of 0.1–1.0 Torr. The ratio of the concentrations of the CH(A2Δ) and CN(B2Σ+) states, NCH(A)/NCN(B), in the desiccated system was found to be smaller than that in the system without desiccation. The [N]/([N]+[C]) ratio of the a-CNx:H films formed in the desiccated system was predicted to be ≈0.18, being nearly independent of PAr.

Dependence of the electronic transition moment for the C3Δ–X3Δ system of TiO on the internuclear distance

Abstract Intensity distributions of eight vibronic bands associated with v ′ =0–3 for the C 3 Δ–X 3 Δ transition of TiO were observed by dispersed emission spectroscopy, and the variation of the electronic transition moment, R e ( r ), for the C 3 Δ–X 3 Δ system was determined as a function of the internuclear distance r ; R e (r)∝{1−2.04(31)(r−r 0 )+195(43)(r−r 0 ) 3 } (r 0 =1.65869 A and 1.59130 A ⩽r⩽1.71214 A ). This r -dependence of R e ( r ) is discussed in terms of the polarization in the unpaired 10 σ orbital.

Roles of Ions and Free Electrons in the Synthesis of Mechanically Hard Amorphous-CNx Films Using a Dissociative Excitation Reaction of BrCN with the Ar Electron Cyclotron Resonance Plasma

A dissociative excitation reaction of BrCN with the Ar electron cyclotron resonance (ECR) plasma was applied to synthesize mechanically hard amorphous carbon nitride (a-CNx) films. The hardness of the films has been measured by a nanoindenter to be at most 15 GPa under the maximum loading force of 50 mN. The self-bias voltage, -Vself, and the I–V characteristics have been measured to discuss the mechanism of hardening of the a-CNx films. It was confirmed that -Vself causes the Ar ion bombardment on the surface of the films, leading to the high hardness value of the films without applying an external bias voltage.

Absolute density of the CN(X2Σ+), v = 0 level produced by the dissociative excitation reaction of BrCN with the microwave discharge flow of Ar

The 4–0 band of the A2Πi–X2Σ+ transition of the CN radical produced by the dissociative excitation reaction of BrCN with the microwave discharge flow of Ar was observed by laser induced fluorescence (LIF) spectroscopy. The absolute number density of the CN(X2Σ+), v=0 level was evaluated to be 5.8(3)×1013 m-3 by an analysis based on a spectral simulation and on a calibration against Rayleigh scattering by Ar atoms.

Raman Scattering Spectroscopy of Structure of Amorphous Carbon Nitride Films

Amorphous carbon nitride (a-CNx), films without hydrogen were deposited with dehydrated cyanogen bromide using electron-cyclotron-resonance plasma-enhanced chemical-vapor deposition. The structure of the a-CNx films was evaluated using a new Raman-active band at ~1300 cm-1, corresponding to sp3-hybridized carbon nitride. The Raman-active scattering band at ~1300 cm-1 became clearer with increasing hardness value of the films, suggesting that the hardness of the a-CNx films increases with extension of the three-dimensional structure of the films composed of C–N bonds.

Water Desorption from Magnesium Oxide Films Fabricated by Chemical Vapor Deposition

Magnesium oxide (MgO) films are utilized for the anti-plasma sputtering coating with excellent ability of secondary electron emission in plasma display panels (PDP). These properties are degraded by the impurities adsorbed on the film surface. Therefore, we should obtain impurity-free surface during the PDP manufacturing process. We have synthesized whisker and continuous film types of metal oxide using a chemical vapor deposition (CVD) method operated under atmosphere. In this study, a temperature programmed desorption method has been applied to detect residual species adsorbed on the surface of the present films in the ultra-high vacuum atmosphere. The amount of water adsorption was determined by this method.