Katsuo Abe

Performance of hard DLC protective film prepared by PECVD method for thin film magnetic disk

Performance of a diamondlike carbon (DLC) film prepared by the PECVD method has been investigated as the protective film of a rigid thin film disk. An in-line sputtering PECVD multilayer deposition system was used for preparation of disk samples. The disks were found to be superior to those disks with conventionally sputtered carbon films in many aspects such as high durability against CSS tests, smooth coverage over the irregular points of the magnetic layer, and as a result, good corrosion resistance even at a thickness of 15 nm or less. >

Planar magnetron sputtering cathode with deposition rate distribution controllability

Abstract A new planar magnetron sputtering cathode was developed in order to reduce the change in the film thickness distribution on the substrate with time. This cathode has two (inner and outer) electromagnet coils coaxially wound on a magnetic yoke behind the target plate. The zero point in the vertical component of the magnetic field in front of the target can be moved by controlling the currents in the two coils. A glow discharge ring between 116 and 160 nm in diameter was obtainable with a target of diameter 254 mm. The deposition rate was higher at the centre of the substrate when the diameter of the glow discharge ring was smaller and vice versa. In order to synthesize a flat distribution two deposition rate distributions were summed on the substrate in such a manner that the glow discharge ring was periodically controlled to have a diameter of 116 and 160 mm ten times during deposition of 1 μm of Al-2%Si. A distribution deviation of ±5% was maintained during the deposition of 2200 μm onto substrates 125 mm in diameter.

Morphological structures and magnetic properties of sputtered thin film media

Morphological structures and magnetic properties of sputtered Co-Ni-Zr/Cr films are investigated in order to clarify the origin of an undesirable magnetic anisotropy induced by inline sputter deposition during disk transfer. The film deposition onto nontextured substrates at lower Ar pressure makes this anisotropy larger. Co-Ni-Zr/Cr films deposited at 1.3 Pa are observed to have bow-like columnar structures of Cr films and a preferential Cr and Co orientation inclined about 20 degrees from the direction normal to the film surface toward the transfer direction. As a result, the tendency of the magnetocrystalline anisotropy axis to face toward the transfer direction causes the magnetic anisotropy. This can be understood to be the origin of the undesirable anisotropy. On the other hand, the films deposited at 4.0 Pa have straight columnar structures of Cr films and a preferential Cr orientation normal to the film surface. It is concluded that the morphological and crystallographic structures of Cr films strongly affect the magnetic properties of Co-alloy/Cr films. >

Development of the Thick - Film Capacitor and Its Application for Hybrid Circuit Modules

New dielectric pastes with high and low dielectric constants and an advanced passivation system have been developed for highly reliable capacitors and crossovers in thick-film circuit modules. Colloidal magnetite has been found to be a good sintering agent in BaTiO 3 -based high-K dielectric paste, and a crystallized low-K glass paste has been found to be suitable for small capacitors and crossovers. Alloyed Ag/Pd and Ag/PdO have been developed for conducting electrodes, which are compatible with the dielectric materials and the firing process. Physical defects are the critical factors in the glass passivation systems for the reliability because of possible moisture diffusion into the dielectrics. A new two-layered passivation system has been adopted. The capacitor system has been applied to an RF/IF thick-film hybrid module for radio-cassette recorders.

H/sub c/ measurement of microscopic regions on thin film magnetic disc using longitudinal Kerr effect

A longitudinal Kerr magnetooptical microscope system with a read/write testing unit and a positioning unit was developed for nondestructive measurement of the coercive force (Hc) in thin-film magnetic disks. This system measures the magnetooptical hysteresis loop from an area 2-30 mu m in diameter on a disk with a C/CoNi/Cr layer. The magnetic field strength at the disk surface was estimated from the coil current in a Weiss-type magnet. The absolute value of the field strength was calibrated by a Hall sensor. The actual H/sub c/ values were measured and compared with the result obtained by a vibrating sample magnetometer in order to determine the accuracy, which was found to be within 2%. It took 36 min. to complete the H/sub c/ measurement at 144 points over a 5.25 in. disk for a mean spot size of 30 mu m. >

In-Plane Crystalline Orientation and Magnetic Anisotropy of Co-Ni-Zr Media

The in-plane crystalline orientation of a longitudinal thin film medium was investigated to clarify the relation between the crystalline orientation and the magnetic anisotropy. As is well known, the anisotropy is induced by deposition onto a moving disk substrate (transport deposition) and is changed by substrate texturing. It has heretofore been difficult to determine the crystalline orientation by X-ray diffraction because of the very intense background reflection. We have developed a precise background correction method enabling measurement of the pole figure of the longitudinal medium. It is clear that the c-axis of a medium on a mirror-polished substrate is essentially oriented in the direction of substrate motion, and that the axis of a medium on a textured substrate tends to be oriented in the texturing direction.

The micro-structure of γ-Fe 2 O 3 film with Ar-O 2 -H 2 O process

The micro-structure of the γ-Fe 2 O 3 film with reactive sputtering process in Ar-O 2 -H 2 O was studied using X-ray diffraction and a cross-sectional High-Resolution TEM. The results are as follows: the film has a columnar structure and the diameter of each column is 100-300 A; both oriented columns and micro-crystallite columns coexist in the film; the crystallinity in the micro-crystallite columns was found to contribute to the magnetic properties.

High rate deposition of MoSi2 films by selective co-sputtering☆

Abstract A new sputtering method has been developed to achieve the high rate deposition of refractory metal silicide films. This method employs a planar magnetron sputtering cathode with two coaxially wound electromagnet coils in a magnetic yoke and a target plate of multiring structure composed of silicon and molybdenum target pieces. The diameter of the glow ring can be changed by controlling the magnetomotive forces in the two electromagnet coils. The target consisted of a centre silicon disc and molybdenum and silicon target rings which concentrically surround the centre silicon disc. The glow ring diameter was controlled so that each of the target pieces was selectively sputtered. The amount of sputtered silicon and molybdenum was adjusted to obtain a film of the required thickness and composition on the substrate. Distributions of the composition and the film thickness of 37±0.5 wt.% Si and ±2% respectively were obtained over a 4 in wafer. The film was annealed at 1000°C for 30 min. A sheet resistance of about 2.3 Ω/□ was obtained for a film 300 nm thick with an average deposition rate of 95 nm min -1.

Thick Film Capacitor Materials of thePowder–Glass Binary Systems and TheirDielectric Properties

Descriptions are given of the fundamental dielectric properties of the thick film binary system, composed of dielectric powder and glass, in relation to the effect of bulk properties of the constituent electrode composition in preventing a decrease in breakdown voltage with time and the effect of glass passivation on the reliability of thick film capacitors.