Tdk Corporation

Masanori Shibahara

Masatoshi Nakayama

Hajime Utsunomiya

Kunihiro Ueda

Isamu Kuribayashi

Toshiki Aoi

Giichi Shibuya

Kenji Uchiyama

Tatsuya Kato

Suguru Takayama

Koichi Yajima

Kenji Nakaya

Kenji Yoneyama

Hideki Ishizaki

Hiroshi Takasaki

Hisaji Oyake

Hirokazu Fujioka

Takashi Onodera

Michiki Naganawa

Takatoshi Ooyama

Michihiro Nemoto

Tsutomu Tsutsumi

The present invention relates to a method for processing a photoresist-coated board, a method for manufacturing a stamper for a recording medium and a method for manufacturing a recording medium which can form a fine raised and depressed pattern having a uniform width after development even in the case where a laser beam having a relatively long wavelength is used for forming pre-pits on a recording medium with high accuracy. A photoresist-coated boardis constituted by laminating a light absorption layerand a photosensitive material layeron a glass substratein this order and is exposed to a laser beamby condensing the laser beamonto the photosensitive material layer, thereby forming a raised and depressed pattern corresponding to pre-pits on the the photosensitive material layer. When the length of a pre-pit to be formed is shorter than 4 T, for example, the duty ratio of the pulse signal train input to the light modulatoris varied within a range from about 50% to 65% so that a pulse signal train having a higher duty ratio is generated as the length of a pre-pit to be formed becomes longer and the power of a laser beam is modulated by the thus generated pulse signal train. On the other hand, when the length of a pre-pit to be formed is equal to or longer than 4 T, for example, a pulse signal train having a constant duty ratio is generated independently of the length of the pre-pit to be formed and the power of a laser beam is modulated by the thus generated pulse signal train.

Processing method for photoresist master, production method for recording medium-use mater, production method for recording medium, photoresist master, recording medium-use master and recording medium

An optical recording medium includes a support substrate, a light transmission layer whose one surface constitutes a light incidence plane through which a laser beam is projected, an information recording layer formed between the support substrate and the light transmission layer, a reflective layer formed between the information recording layer and the support substrate, a water proof layer formed between the reflective layer and the support substrate and containing a mixture of ZnS and SiOas a primary component, and a corrosion resistant layer formed between the water proof layer and the reflective layer. According to the thus constituted optical recording medium, it is possible to effectively prevent a reflective layer from being corroded and has excellent storage reliability.

Optical recording medium

The optical recording medium of the present invention is a phase change optical recording medium which can be used as a write once medium and which can be recorded at a high recording density. The optical recording medium of the present invention is adapted for recording such that, when the recording beam has a wavelength of &#x3bb;, and objective lens of recording optical system has a numerical aperture of NA, minimum record marks formed are circular or ellipsoidal marks having a length of 0.4 &#x3bb;/NA or less; and the medium is a write once medium wherein the recorded information can not be erased or rewritten at the minimum linear velocity used.

In a phase change optical recording medium, time required for recording the unrecorded area as well as jitter produced are reduced. Provided is an optical recording method for recording an optical recording medium having a phase change recording layer, wherein the recording is conducted such that: V /V >1, and 0.3<P /P <1 when unrecorded area of the recording layer is recorded by using a linear velocity of V and an erasing power of P and overwritten by using a linear velocity of V and an erasing power of P ,

Optical recording method, optical recording apparatus, and optical recording medium

Articles having a diamond-like protective film formed thereon, each comprising a substrate of a material selected from the group consisting of alloys containing at least Co, Ni, or Fe, ceramics, and glass and which has only a slight affinity for a diamond-like thin film, an Mo film formed on the substrate, and a diamond-like thin film formed further thereon. Such articles are manufactured by a method which comprises holding a grid made of Mo close to the surface of the substrate, bombarding the grid and the substrate surface with a bombarding gas consisting of inert gas atoms of Ar or the like, thereby removing contaminants from the surface and depositing Mo atoms on the substrate surface to form an Mo film thereon, ionizing a low-molecular-weight hydrocarbon or a feed gas capable of producing a low-molecular-weight hydrocarbon upon decomposition or reaction, and then accelerating the resulting ions and depositing the same on the Mo film to form a diamond-like film thereon. The substrate is preferably a metallic mold constructed of a hardened steel. The Mo film enhances the bond of the diamond-like film to the substrate and improves the strength of the mold surface.

Articles having diamond-like protective film and method of manufacturing

A protectively coated article comprises a substrate of a material selected from the group consisting of alloys containing at least Co, Ni, or Fe, ceramics, and glass and which has only a slight affinity for a diamond-like thin film, an intermediate carbon layer formed on the substrate, the intermediate layer having a hardness Hv in the range from 1000 to 5000 kg/mm2, or harder than the substrate but less hard than a diamond-like thin film to be formed thereon, and a diamond-like thin film formed further thereon. The interposition of the intermediate layer permits the diamond-like thin film to be bound securely to a substrate surface which has a slight affinity for the film.

Articles having diamond-like protective film

The present invention improves the adhesive property by pretreating under uniform conditions the substrate surface of metal, ceramics or glass etc. with a poor adhesive property, by accelerating ions under an electric field to the substrate in advance of a diamond-like film forming process. In light of the fact that a diamond-like film forming process by ionized deposition uses thermal electron ionization means and an electric potential is applied to a grid to accelerate ionized hydrocarbon ions, the present invention could attain the aimed purpose by ionizing and then accelerating a bombardment gas such as argon as a pretreatment process in the same apparatus.

Process for forming diamond-like thin film

A magneto-optical disc includes a pit forming region and a groove forming region on a surface of a substrate and a recording layer covering the pit and groove forming regions. The pit forming region includes a row of pits having a width of 0.40-0.55 .mu.m and a depth of 600-900 .ANG. and the groove forming region includes a spiral groove having a width of 0.95-1.15 .mu.m and a depth of 600-900 .ANG.. The disc is recorded and read by using an optical head with an objective lens having a numerical aperture of 0.40 to 0.50 and directing linearly polarized laser light having a wavelength of 600 to 900 nm to the disc such that its electric field vector has a direction perpendicular to the groove and the pit row. Tracking, seeking and information retrieval can be done with minimal errors using the same laser light beam in both the pit and groove forming regions.

Magneto-optical disk

In a magneto-optical recording disc of the magnetic field modulation recording mode, recording of information for the first time is carried out in an optical modulation mode at a linear velocity which is higher than a reading linear velocity. The time required for recording is reduced while the recorded disc produces satisfactory outputs on playback.

Magneto-optical recording method and method for making

Articles protectively coated with a diamond-like thin film firmly bonded to the substrates are obtained by forming an intermediate layer composed of an amorphous mixture of silicon and carbon on a substrate of a material which has only a slight affinity for such a diamond-like thin film, and forming a diamond-like thin film further thereon.

Articles having diamond-like protective thin film

An apparatus for generating a modulated magnetic field includes a magnetic head coil and a pair of additional inductive coils. The ratio of the average inductance of the additional inductive coils to the inductance of the head coil is from 2 to 8. The apparatus ensures a magneto-optical recording system of the magnetic field modulation mode having an increased switching speed and a minimized overshoot of recording current.

Magneto-optical head circuit for minimizing the overshoot reversing

A magneto-optical disk is made up of a disk form of substrate including on its surface a recessed area having at least one of a groove and pits, and a recording layer provided such that it covers the recessed area. The geometry of at least one of the groove and pits is designed to conform to .theta..sub.10 .gtoreq..theta..sub.50 and .theta..sub.50 &gt;.theta..sub.90 where .theta..sub.10, .theta..sub.50 and .theta..sub.90 are respectively the angles that tangential lines make with horizontal lines at 10%, 50% and 90% depth positions of a side wall of the recess in the diametrical direction of the substrate. This magneto-optical disk is improved in terms of the push-pull signal level, radial contrast, skew margin and C/N.

Magneto-optical disk having lands and grooves for recording information

In a magneto-optical disk comprising a disk-shaped substrate including a grooved region in its surface and a recording layer covering the grooved region, the groove is defined by a pair of opposed side walls and a bottom in a radial cross section of the substrate and has a depth from the substrate surface to the groove bottom. The angle .theta. included between tangents to the side walls is at least 120 degrees, and the groove has a half-value width of 0.90 to 1.15 .mu.m and a depth of 600 to 900 .ANG.. The disk produces satisfactory values of push-pull signal level, radial contrast, and C/N ratio.

A diamond-like thin film formed on a substrate, with the peripheral region tapered toward the edge, satisfying the dimensional relation

Process for manufacturing diamond-like thin film

Diamond-like thin films having high uniformity and high crystallinity are produced by introducing a hydrocarbon material gas into a chamber, ionizing the gas, and depositing the ionized gas on a substrate. The gas is ionized by thermionic emission from two or more files of hot cathodes, each file having a plurality of filaments arranged at substantially uniform intervals in a linear or zigzag line configuration. Each file of hot cathodes is surrounded separately by an anode at a substantially uniform distance from a respective file of the filaments.

Growing community of inventors

Nagano, Japan

Masanori Shibahara