Hitachi, Ltd.

Nobuo Nakagawa

Katsuo Abe

Yoshiki Kato

Hitoshi Oka

Hirayoshi Tanei

Hideaki Tanaka

Hitoshi Yokono

Masaaki Hayashi

Shigeru Kobayashi

Masaki Ohura

Takao Nakamura

Kenji Furusawa

Tokio Isogai

Noriaki Okamoto

Satoshi Matsunuma

Tsuneaki Kamei

Norikazu Tsumita

Yoshihiko Miyake

Hiroyuki Kataoka

Hiroaki Okudaira

Shigehiko Fujimaki

Kenichi Gomi

Makoto Kitoh

Osamu Miyazawa

Yuichi Kokaku

Isamu Tanaka

Toyoji Okuwaki

Akira Matsuo

Yoshio Gobara

Kazuyuki Fujimoto

Shoichi Sawahata

Takao Edamura

Masako Fujisawa

Katuo Uda

Maki Kondo

A plasma processing apparatus comprising: a vacuum container; an evacuation means for keeping the interior of the vacuum container at a pressure not higher than atmospheric pressure; a substrate support device for supporting a substrate to be subjected to plasma processing; an electrode for generating plasma in cooperation with the substrate support; a voltage supply for applying a voltage to the electrode; a gas introducing system for introducing a gaseous material into a space where the plasma is produced; a surrounding member for enclosing the space above the substrate support, and a drive for relatively moving the surrounding member to space an end of the surrounding member proximate from the substrate from at least one of the substrate support and the substrate supported thereon by a distance which is short enough to suppress plasma leakage during the plasma processing and to position the end of the surrounding member away from said at least one of the substrate support and the substrate thereon for charging and discharging of the substrate.

Plasma processing method and apparatus

A substrate for a magnetic disc, which comprises a crystallized glass consisting essentially of an amorphous glass continuous phase and crystal particles dispersed in the continuous phase, the substrate having fine projections of the crystal particles on the surface thereof, a method of producing the substrate, the magnetic disc using the substrate, and a method of producing the magnetic disc are provided. The crystallized glass is made from a glass material of a Li.sub.2 O--SiO.sub.2, Li.sub.2 O--Al.sub.2 O.sub.3 --SiO.sub.2, Li.sub.2 O--MgO--Al.sub.2 O.sub.3 --SiO.sub.2, MgO--Al.sub.2 O.sub.3 --SiO.sub.2, Na.sub.2 O--Al.sub.2 O.sub.3 --SiO .sub.2 or BaO--Al.sub.2 O.sub.3 --SiO.sub.2 system, and the crystal particles have one or more compositions selected from Li.sub.2 O--SiO.sub.2, Li.sub.2 O.2SiO.sub.2, Li.sub.2 O.Al.sub.2 O.sub.3.2Si.sub.2, Li.sub.2 O.Al.sub.2 O.sub.3 4SiO.sub.2, SiO.sub.2 and 2MgO--2Al.sub.2 O.sub.3.5SiO.sub.2, and an average particle size of 0.01 to 3.0 .mu.m, and are projected at a density of 10.sup.2 to 10.sup.6 / mm.sup.2 and at an average height of 0.005 to 0.2 .mu.m on the surface of the substrate, the total surface area of the projections of crystal particles occupying at most 30% of the unit surface area of the substrate. The projections are made by chemical etching with an aqueous solution of hydrofluoric acid, physical etching with sputtering under vacuum or ion-milling, or mechanical etching with sand blasting. The magnetic disc comprises the crystallized glass substrate, a chromium or chromium alloy undercoat film, thin magnetic film, protective carbon film and lubricant film.

Magnetic disc substrate

There is provided a magnetic disk apparatus including at least one magnetic disk having a magnetic layer and a surface protective layer on a substrate; a magnetic head which faces the magnetic disk in a rotating state with a micro gap and is supported by a slider; rotating means for rotating the magnetic disk; and magnetic head positioning means for moving and positioning the magnetic head to a predetermined position on the magnetic disk, wherein a plurality of protrusions each having a flat surface are formed in at least a region on the surface of the magnetic disk where a contact start/stop operation can be executed, an area ratio of the protrusions per 1 mm.sup.2 lies within a range from 0.1 to 80%, a height of the protrusion of the maximum height among the protrusions lies within a range from 5 to 40 nm, and the magnetic layer is formed on the whole surface on the base plate. According to the above magnetic disk apparatus, the frictional force between the disk and the head is small, and the floating height of the head can be reduced, and good floating stability is obtained, so that excellent recording and reproducing characteristics are obtained.

Magnetic disk with surface protective layer having convex portions and

A substrate for a magnetic disc, which comprises a crystallized glass consisting essentially of an amorphous glass continuous phase and crystal particles dispersed in the continuous phase, the substrate having fine projections of the crystal particles on the surface thereof, a method of producing the substrate, the magnetic disc using the substrate, and a method of producing the magnetic disc are provided. The crystallized glass is made from a glass material of a Li.sub.2 O-SiO.sub.2, Li.sub.2 O-Al.sub.2 O.sub.3 -SiO.sub.2, Li.sub.2 O-MgO-Al.sub.2 O.sub.3 -SiO.sub.2, MgO-Al.sub.2 O.sub.3 -SiO.sub.2, Na.sub.2 O-Al.sub.2 O.sub.3 -SiO.sub.2 or BaO-Al.sub.2 O.sub.3 -SiO.sub.2 system, and the crystal particles have one or more compositions selected from Li.sub.2 O.multidot.SiO.sub.2, Li.sub.2 O.multidot.2SiO.sub.2, Li.sub.2 O.multidot.Al.sub.2 O.sub.3 .multidot.2SiO.sub.2, Li.sub.2 O.multidot.Al.sub.2 O.sub.3 .multidot.4SiO.sub.2, SiO.sub.2 and 2MgO.multidot.2Al.sub.2 O.sub.3 .multidot.5SiO.sub.2, and an average particle size of 0.01 to 3.0 .mu.m, and are projected at a density of 10.sup.2 to 10.sup.6 /mm.sup.2 and at an average height of 0.005 to 0.2 .mu.m on the surface of the substrate, the total surface area of the projections of crystal particles occupying at most 30% of the unit surface area of the substrate. The projections are made by chemical etching with an aqueous solution of hydrofluoric acid, physical etching with sputtering under vacuum or ion-milling, or mechanical etching with sand blasting. The magnetic disc comprises the crystallized glass substrate, a chromium or chromium alloy undercoat film, thin magnetic film, protective carbon film and lubricant film.

Magnetic disc comprising a substrate of an amorphous glass continuous

Disclosed is a magnetic recording medium in which an underlayer formed below a magnetic medium, in which a signal is written, is composed of a nickel alloy comprising 0.05 to 10 atom % of tungsten and 14 to 30 atom % of phosphorus. In this magnetic recording medium, the temperature for formation of magnetic medium and the temperature for formation of a protective film can be elevated over the levels adopted in the conventional techniques. Therefore, the magnetic characteristics and abrasion resistance can be improved. Furthermore, the magnetic recording medium is excellent in the mechanical strength and corrosion resistance. Accordingly, the reliability of the magnetic medium can be highly improved.

Magnetic recording medium having an amorphous, nonmagnetic

A film forming method by plasma sputtering is provided to attain a composite film on a substrate. A target plate having metal materials in a different pattern is prepared in opposition to the substrate. A plasma is created by a planar magnetron sputtering electrode structure. The plasma is shifted magnetically on the target plate by at least three magnetically coupled magnetic poles to deposit the materials into a film with a uniform thickness and a desired composition on the substrate.

Film forming method

A base plate for magnetic recording disc is produced by coating thin metal layers containing no impurities for forming defects by an anodizing treatment on one or both sides of a discoid substrate made of a metal such as aluminum or an aluminum alloy or from a plastic by a dry process, and anodizing the thin metal layers so as to form anodized film from the surfaces of the thin metal layers to a certain depth while the portions contacting to the substrate are retained not anodized.

Base plate for magnetic recording disc

When an amine compound having at least two polyolefin glycol chains in one molecule is used as a stabilizer, and an alkylene diamine compound, at least one hydrogen atom in the respective amino groups thereof being substituted by CH.sub.2 COOX (wherein X is H or Na) and another hydrogen atom in the respective amino group thereof being substituted by CH.sub.2 OH, is used as a complexing agent for cupric ions and a nitrogen-containing cyclic compound is used as a complexing agent for cuprous ions in an electroless copper plating solution comprising water, a water-soluble copper salt, a complexing agent for cupric ions, a reducing agent, a pH-controlling agent and a stabilizer, or an electroless copper plating solution comprising water, a water-soluble copper salt, a complexing agent for cupric ions, a reducing agent, a pH-controlling agent, a stabilizer and a complexing agent for cuprous ions, the plating rate of the electroless copper plating solution, mechanical strength of plating film, and stability of the plating solution are improved.

Electroless copper plating solution

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Yokohama, Japan

Nobuo Nakagawa