M. Ikeyama

Deposition of diamond-like carbon films using plasma based ion implantation with bipolar pulses

Plasma based ion implantation (PBII) with bipolar pulses has been proposed to improve a dose uniformity in an ion implantation on a three-dimensional target. A pulsed glow discharge plasma is produced around the target by a positive pulse at a gas pressure less than ∼0.5 Pa, and then ions are implanted into the target from all sides by the subsequent negative high-voltage pulse. It has been shown that ions produced by the positive pulse have been implanted effectively with the negative pulse. The PBII with bipolar pulses is applied to DLC coatings. A carbon mixing layer in the substrate surface is formed by the implantation to improve the adhesion of DLC films. Internal stress of DLC films slightly decreases with increasing frequencies of positive pulse. Moreover, it is shown that the PBII with bipolar pulses is possible to use for inner coating of DLC films on a stainless-steel pipe.

Dynamic MC simulation for a-C:H deposition in methane plasma based on subplantation model

Abstract We have applied dynamic Monte Carlo simulations to the synthesis of a-C:H films by PBII. Like our previous model, we assumed a surface reaction layer consisted of one or two monolayers of a-C:H, in which very low threshold displacement energies are used, so atoms are knocked on by the collisions with energetic ions much easier than in the bulk substrate. Only atoms with energy higher than the barrier can penetrate into the subsurface. The change from the previous model is in the treatment of sp 3 state forming. Our new model is based on the subplantation model proposed by J. Robertson [1] . The sp 3 state formation was assumed resulted from the density increase. In the subsurface, among the penetrated C atoms, only atoms with low energy which is not enough to induce collision cascade form sp 3 state together with the surrounding C atoms and the other C atoms with higher energy form sp 2 state because of the density relaxation induced by the dense collision cascades. In addition to the above assumption, release of the displaced H atom after the subsequent collision cascade is assumed. The calculation is centered on how the sp 3 fraction and the H concentration, and the growth rate depend on the incident energy, the ion/neutral ratio, threshold energy of sp 3 formation. The energy dependence obtained for both sp 3 fraction and H concentration agreed well with the experimental data.

Computer simulation of plasma for plasma immersed ion implantation and deposition with bipolar pulses

In order to analyze the plasma behavior under the plasma immersion ion implantation and deposition (PIIID when a negative pulse voltage is applied to a target, a weak plasma is generated around the target. In contrast, when a positive pulse voltage is applied, a more intense plasma is generated under the same conditions. The results obtained by simulation of the behavior of ions and electrons near a trench-shaped target are presented.

Optical property changes in sapphire induced by triple-energy Cu and O implantation

Abstract Triple-energy Cu and O ions were implanted into sapphire, changing the ratios of Cu and O doses and the implantation sequence as follows: Cu only (1:0); Cu+ 1 / 2 O (1:0.5); Cu+O (1:1); 1 / 2 O+Cu (0.5:1); and O+Cu (1:1) at room temperature (300 K). Optical property changes induced by the ion implantations and successive heat treatments were studied. Specific optical absorption is clearly observed at approximately 590 nm, which is attributed to Cu nano-particles, for Cu-implanted sapphire after annealing at 1070 and 1270 K. The intensity is drastically changed between 1070 and 1270 K. A broad absorption centered at approximately 300 nm is also observed for samples annealed at 770 and 1070 K. For Cu and O co-implantation, an increase in O dose leads to lower absorption on the whole. The absorption at approximately 590 nm is observed after annealing at 1070 or 1270 K for Cu+ 1 / 2 O and Cu+O, but not for 1 / 2 O+Cu and O+Cu implantation. In general, optical absorption of sapphire increases after annealing, especially in the short-wavelength region, and this can be attributed to copper oxide formation. The formation of Cu, Cu 2 O and CuO nanoparticles was confirmed by XRD measurements. CuO and Cu 2 O are easily formed at a lower annealing temperature, whereas Cu nanoparticle formation requires a higher annealing temperature. The sequence of ion implantation for Cu and O affects the optical absorption and nanoparticle formation.

Plasma analysis for the plasma immersion ion implantation processing by a PIC-MCC simulation

Abstract In order to analyze the plasma behavior during PIII processing, a computer simulation has been carried out using the simulation software “PEGASUS”. The software uses a Particle-in-Cell (PIC) method for the movement of charged particles in the electromagnetic field and a Monte Carlo method for collisions of ions, electrons, and neutrals in the plasma and also a Monte Carlo method to analyze the background gas behavior for a low density gas system. This approach is based on the weighting collision simulation scheme allowing for disparate number densities of different species. The spatial distributions of potential and densities of ions, electrons and radicals in the coating system were calculated together with the flux of ions and electrons on the surface of the object. The gas pressure was 0.01 to 50 Pa and a negative and/or a positive pulse voltage ( V max = 0.1 to 20 kV) was applied to the object. The calculation is fully self-consistent. A two-dimensional Cartesian and a cylindrical coordinate system were used. The effects of gas pressure, applied voltage, and secondary electron emission coefficient by ion impact (γ) on the sheath thickness, the spatial distribution of densities of electron, ion, and neutral atoms, the ion flux and its spatial distribution, etc. were studied for PIII processing of a trench shaped object, inner wall of a pipe and a PET bottle.

Deposition of perfluoropolyether lubricant films on Si-incorporated diamondlike carbon surfaces

In this article, the bonding characteristics of perfluoropolyether (PFPE) molecules, having a hydroxyl end group, regarding Si-incorporated amorphous carbon surfaces were investigated. The Si contents in the carbon films were varied from 0to10.3at.%. The PFPE lubricant layers were deposited on the carbon surfaces using the traditional dip coating and vacuum vapor deposition. It was found that the Si incorporation enhances the bonding of the PFPE molecules on the carbon surfaces. Moreover, the bonding of the PFPE molecules increases with the increasing Si content in the carbon film. This is attributed to the structural and chemical modifications of the hydrogen-terminated carbon surfaces due to the Si incorporation into the carbon network, which increases the adsorption sites for the PFPE molecules. The bonding of the PFPE molecules is enhanced using a vapor deposition technique compared to the traditional dip coating. The Si-incorporated carbon films represent a reasonably high hardness and a good bonding...

Vapor deposition of strongly bonded hydrocarbon films on diamondlike carbon surfaces

In this report, we describe the deposition of strongly bonded hydrocarbon films (1-decanol and decanoic acid) on carbon surfaces by a vacuum vapor deposition technique. From the contact angle test and x-ray photoelectron spectroscopy measurement results, we conclude that the hydrocarbon molecules having hydroxyl or carboxyl end groups can be strongly bonded on carbon surfaces by vapor deposition. It is related to the electrostatic interaction between hydroxyl or carboxyl end groups and unsaturated electrons on carbon surfaces. The friction measurements results are also discussed.

Synthesis of MAX-Phase Containing Ti-Si-C Films by Sputter-Deposition Using Elemental Targets

The synthesis of Ti-Si-C thin films by magnetron sputtering was examined using elemental targets of titanium, silicon and carbon, in order to investigate the effects of carbon contents in the films on the formation of such carbide compounds as TiC and/or Ti3SiC2. The thin films were deposited on silicon substrates heated at around 800 degree centigrade in the atmosphere of argon. Obtained Ti-Si-C films were composite materials consisting of Ti3SiC2 MAX phase, TiC phase and graphite phase. Physical and mechanical properties of the film depended on each amount of these 3 phases. And the each amount of these 3 phases depended on the carbon content in the film. Thus film properties could be controlled by the amount of carbon supplied by sputter-deposition. A noteworthy electrical resistivity less than 80μΩcm was achieved.

Deposition of Ti/C nano-composite thin films by magnetron DC sputtering using dual targets

Deposition of Ti/C nanocomposite thin films by magnetron DC sputtering was examined using dual targets of titanium and carbon, in order to investigate the effects of the distribution of titanium atoms and carbon atoms in the films on their surface morphology and their mechanical properties or physical properties. The Ti/C nano-composite thin films were deposited on glass substrates in the atmosphere of argon at the pressure of 0.4Pa by co-sputtering of both a titanium target and a carbon one.