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The kinetic ballooning mode destabilized by the ion magnetic curvature drift resonance in the 2nd ballooning stability regime is shown to be a plausible candidate for the low-k broadband fluctuation recently observed in the wide-pedestal quiescent-H (QH) mode of DIII-D. With its intrinsic real frequency approaching very closely to the ion pressure diamagnetic frequency in the pedestal-like condition with a steep gradient, this mode can be nearly free from the first-order ExB flow shear effect driven by the ion pressure gradient. As a result, it can be sensitive to the next-order one by toroidal rotation, with the possible strong excitation in the low toroidal rotation limit. The frequency in the lab frame and the peak wavenumber spectrum of the mode appear to be in the range similar to those of the observed low-k fluctuation.

Recent analyses [for example, see the paper by G.M. Staebler et al., Phys. Plasmas 056113 (2018)] indicate that in DIII-D high poloidal-beta discharges turbulent transport, particularly for ions, are governed by the electromagnetic kinetic ballooning mode (KBM) in most radial region, including the outer core between internal and external transport barriers (ITB and ETB). Considering that in the usual L- or H-mode plasmas turbulent transport is widely believed to be dominated by the electrostatic drift-type modes, such as the ion temperature gradient (ITG) or trapped electron mode (TEM), a modeling study is presented about how this transition of dominant mode can occur. In the ITB region, where there already exist several theoretical models, the focus is put on clarifying the relative role between the Shafranov-shift and linear electromagnetic effects. While these two can play an important role for the transition or ITB formation by stabilizing the electrostatic drift-type modes, a significant difference is found in that the former mainly works on the TEM, while the latter on the ITG. In contrast to the ITB region, in the outer core between ITB and ETB the transition appears to be more relevant to the destabilization of KBM itself, rather than the stabilization of electrostatic modes. A jump of edge plasma beta through pedestal formation is shown to play the critical role in this destabilization by making the KBM threshold temperature gradient smaller than the ITG/TEM one, thus allowing an earlier excitation of KBM when background temperature gradients increase by external heating.

The optical flying head (OFH) was designed and fabricated for implementation of the first surface magneto-optical (MO) recording technology. The OFH structure for integration with the small ball lens and double-layer microcoil has been developed. An objective lens and microcoil thinned by 30 µm were attached to the OFH. It was found that the OFH could fly above the disk media at a more than 100 nm flying height with a 2 µm lens bottom-to-disk cover layer gap; and the microcoil had a 20 Ω resistance and 160 nH inductance as measured up to 100 MHz. The performances of the OFH and microcoil were adequate to demonstrate the feasibility of the magnetic field modulation (MFM) MO recording technology.

We studied the effective design of a head structure to realize a practical optical flying head (OFH) for near-field recording (NFR) with both high optical performance and reasonable tolerance in assembly. In the design of the OFH, several major issues such as productivity, performance and reliability were considered. In order to realize a stable and reliable OFH with high performance, we designed a slider structure, air bearing surface (ABS), coil for magneto optical (MO) recording, main optical pickup unit (OPU), suspension and gimbal structure, disk media for good head-disk interface, and so forth. With a view to the reliability of OFH, durability and flying stability for various plastic disks as well as on a conventional glass disk were investigated. Also with a view to the practical applicability, we proposed two OFH designs with simple and effective slider structures, namely a slot slider and a barrel slider. In addition, basic flying characteristics and optical performance of the OFH mounted with high NA optics were tested and evaluated. Attempts have been made to develop engineering plastic and polycarbonate disks as well as glass as disk media for NFR application. The durability of developed disks was examined and compared with the aim of their practical application.

We will report on new dc-free runlength-limited codes (DCRLL) intended for the next generation of digital versatile disc (DVD). The efficiency of the newly developed DCRLL schemes is extremely close to the theoretical maximum, and as a result, significant density gains can be obtained with respect to prior art coding schemes. Preferred embodiments of the codes (footprints) and respective hardware realization will be considered.

Benzotriazole (BTA) has been used to protect copper (Cu) from corrosion during Cu chemical mechanical planarization (CMP) processes. However, an undesirable Cu–BTA complex is deposited after Cu CMP processes and it should be completely removed at post-Cu CMP cleaning for next fabrication process. Therefore, it is very important to understand of Cu–BTA complex formation behavior for its applications such as Cu CMP and post-Cu CMP cleaning. The present study investigated the effect of pH and polisher conditions on the formation of Cu–BTA complex layers using electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy) and the surface contact angle. The wettability was not a significant factor for the polishing interface, as no difference in the contact angles was observed for these processes. Both electrochemical techniques revealed that BTA had a unique advantage of long-term protection for Cu corrosion in an acidic condition (pH 3).

A wireless wafer-type probe system was developed to measure two-dimensional plasma parameters and uniformity. The apparatus uses double probe theory with a harmonic detection method. The plasma parameters, such as the electron temperature, ion density and ion flux, are derived by using the amplitudes of the first and third harmonic currents. The experiment was conducted in an inductively coupled plasma. The measurements of the wireless wafer-type probe were compared with a floating-type Langmuir probe and a similar trend was observed. As the inner and outer antenna current ratio changes, the wireless wafer-type probe was able to measure the evolution of the two-dimensional ion density profiles. Since the wireless wafer-type probe system was electrically isolated and designed to operate stand-alone in the chamber, it can be installed in plasma chambers without any external controllers. This plasma diagnostic system shows promise for processing plasmas.

A double probe diagnostic using an ac bias signal between both probe tips was developed. The electron temperature and electropositive ion flux were derived by analyzing the first and third harmonic currents of the probe. The double probe was compared with the floating-type single probe at various RF powers and pressures in an inductively coupled plasma. The electron temperature and electropositive ion flux measured from the double probe agreed with the measurements from the floating-type single probe. This methodology can be applied to an electrically isolated diagnostic system for processing plasmas.

We have suggested methods to achieve read/write compatibility for a high-density (HD) disk of 0.1 mm substrate thickness and digital versatile disk of 0.6 mm substrate thickness by simply adding an optical element. We have confirmed that the polarized holographic optical element (HOE) and polarized phase compensator (PPC) are strong candidates for achieving compatibility.

Control of type-I ELMy H-mode by pellet injection is numerically investigated for KSTAR and ITER. Inverse proportionality of pellet-induced edge localized mode (ELM) energy loss to pellet injection frequency is found to be similar with spontaneous ELMs in KSTAR. Pellet injection frequency is proposed to be a key parameter to control the ELM frequency and resultantly the ELM energy loss. Extending KSTAR modelling, a pellet-induced density perturbation model is applied to the ELMy H-mode discharge of ITER so that the control of type-I ELMy H-mode by pellet injection is demonstrated to check the availability of pellet ELM pacing for mitigating ELM peaks in ITER. The simulation predicts that 25 MJ of energy loss could be released by type-I ELM in ITER which exceeds the material limit of plasma-facing components (PFCs). However, the ELM pacing simulation indicates that pellet injection from high-field side and low-field side in ITER can significantly mitigate the ELM energy loss by up to a factor of 7.35 at 20 Hz of pellet injection. The performance of pellet pacing is expected to be effective but still might be insufficient to satisfy engineering restrictions of PFCs. Further improvements of mitigation performance will be required to achieve fully controlled ELMy H-mode plasmas in ITER.

The contact resistance (R C) between a Ru electrode and a TiN plug in a crystalline Ta2O5 capacitor using Ru electrodes was evaluated. The TiN plug was oxidized in TiO x to increase the R C to failure. Two origins of oxygen are determined by Auger electron spectroscopy (AES) analysis, namely, the seed step of Ru deposition and the initial step of Ta2O5 deposition. During Ta2O5 crystallization annealing at 700°C, the oxygen molecules from Ru diffused into the TiN plug, forming TiO x . Ru films with Ti exhibited a decreased R C below 1 kΩ/contact and an increased leakage current of a Ru/Ta2O5/Ru capacitor according to the applied voltage, compared with Ru films without Ti. The atomic layer deposition (ALD) Ru process including a H2 plasma treatment decreased the R C to 2.5 kΩ/contact on average. The fabrication scheme for the crystalline Ta2O5 capacitor using the Ru electrode for reducing RC between the Ru storage node and the TiN plug was proposed.

Ru thin films were prepared by metalorganic chemical vapor deposition (MOCVD) using cyclopentadienyl-propylcyclopentadienlylruthenium(II) [RuCp(i-PrCp)] and the nucleation behaviors of Ru films on Ta2O5, TiN, Si3N4, SiO2, TiO2 substrates were investigated. It appeared that the difference in nucleation behaviors on various substrates is due to the bonding type between atoms in substrate materials. The nucleation property of Ru films on TiN was successfully improved by plasma treatment of the TiN substrate using Ar before film deposition. It was found that the Ar plasma treatment selectively removes N ions from the surface, makes the TiN surface more metallic or ionic (due to the residual Ti-O bonding), and reduces the nucleation barrier. In addition, the oxidation resistance of Ru/TiN layers was improved by H2 annealing, which made the Ru films more dense.

In a small-form-factor (SFF) optical disk drive (ODD), the optical flying head (OFH) on a thin-cover-layered plastic disk requires not only uniformity of the cover layer thickness of the disk media, but also the flying stability of OFH on the plastic disk surface with low flying height variation, as well as precise tolerance management in the OFH assembly. Therefore, in order to develop a practical optical pickup head interfaced to the plastic disk, we designed the OFH with a parallel-plate electrostatic actuator for the vertical positioning of the objective lens for better flying characteristics. The flying height of the OFH is designed to be 200 nm to increase air-bearing stiffness. On the other hand, a UV resin cover layer is adopted as a protective layer and a hard and stiff plastic substrate is also adopted to increase the durability of the disk. In the evaluation of the stability of the OFH and the durability of the disk, we introduce computational and experimental results on the flying height variation of the OFH, additionally we investigated the characteristics of the durability of various plastic disks.

Recently, there has been a trend to lower the tilt margin in multifunctional rewritable optical disk drives and many attempts have been made to construct a servo system to compensate the tilt in such devices as compact disk-rewritable (CD-RW) or digital versatile disk-random access memory (DVD-RAM) drives in view of rewritable disks. However, in the slim-type drives for Notebook PCs, it is very difficult to realize mechanisms for tilt servo without accompanying impairment of the gain property, due to spatial constraints. In this paper, we suggest a method of controlling the driving force to diminish the variance of mechanical tilt over the entire movable range of wire-spring-suspension-type actuators, and propose a process for precise analysis of driving force. In addition, based on the results of force analysis, we present the conditions that minimize the phase disturbance in subsidiary resonances which have adverse effects on the servo performance of slim-type pickup actuators.

A practical model for precise simulation of the high density disc (19.5 GB) channel is suggested and compared with the linear convolution model. Nonlinear effect compensation is shown to be useful for the practical approach. Partial response maximum likelihood (PRML) simulation results with the nonlinearity compensated channel model are presented.

We developed a rewritable optical disk format with a new addressing method using phase-modulated wobble signals in a land/groove recording structure. The disk format is able to increase the recording density compared with that of the digital versatile disk-random access memory (DVD-RAM) standard by reducing the redundancy due to header fields, and to improve random accessibility compared with that of the digital versatile disk-rewritable (DVD+RW) standard on account of a frame addressing with 104 wobble signals.

An optical pickup actuator is an objective lens moving mechanism that provides a means to accurately follow the disk displacement. Recently, since drive speed and physical density of the optical disc have become higher, better performance and higher precision are required of the actuator. Moreover, small and thin design has become desirable. In addition, a compact disk/digital video disk (CD/DVD)-compatible pickup may require different actuator design. In this paper, we introduce an optimal design method that complies with these requirements. Sample actuators are made with optimally designed parameters. The performance of the samples is evaluated and compared with simulated data. The results prove the effectiveness and validity of the proposed method. We expect them to be used in CD/DVD-compatible pickups.