JPS6267748A - Photomagnetic recording element - Google Patents

Abstract

PURPOSE:To improve safety and handling by sticking an org. substrate as a protective material to a disk substrate made of glass. CONSTITUTION:A dielectric layer 16 is formed on the disk substrate 15 consisting of a doughnut-shaped un-polished glass sheet having guide grooves in order to increase a Kerr rotating angle. A recording layer 17 consisting of a magnetic material film having the axis of easy magnetization in the direction perpendicular to the film plane such as, for example, amorphous magnetic Tb.Co layer, is formed on the dielectric layer 16. The protective layer 18 consisting of a dielectric material such as, for example, SiO2 or SiN, is formed on the recording layer 17 so as to protect and hermetically seal the recording layer 17. A reflection layer 19 consisting of a metallic layer is formed on the protective layer 18 in order to increase reflected light in the stage of reproducing and reading out and to improve C/N. The recording medium 11 is constituted of such disk substrate 15 made of the glass and the plural thin films. The safety, the ease of handling and the longer life are thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magneto-optical recording element that records or erases information using thermal energy and reproduces information using interaction between light and magnetism.

[Technical background of the invention and its problems] In recent years, research and development of optical memory devices capable of high density, large capacity, and high speed access have been actively conducted in various fields.

Among these, magneto-optical memory devices capable of recording, reproducing, and erasing information are considered to be particularly promising because they can be used as file memories for characters and images, computer memories, and the like.

The recording material of this magneto-optical memory device is Tb Co
, GdCo, TbFe, GdTb
Amorphous alloy thin films of rare earths and transition metals such as Fe and Tb Dy Fe are suitable. This is because the amorphous alloy thin film of rare earths and transition metals has an axis of easy magnetization perpendicular to the film surface.
This is because since it is amorphous, there is no grain boundary noise, and it has an invasive property that allows the laser power required for recording to be reduced. However, when an amorphous alloy thin film of rare earth and transition metals is used as a recording material, the Kerr rotation angle, which is a magneto-optical effect, is small at 0.2 to 0.3 degrees, and the quality of the reproduced signal is poor. be. In order to improve the quality of this reproduced signal, a dielectric film of SiO or SiO2 is formed on the recording material or between the substrate and the recording material.
For example, efforts have been made to increase the car rotation angle.
Journal of Appl published by American Physical Society
ied physics VO+, 45°NH3
, August 1974, p. 3643).

Further, the disk substrate forming the recording material has been proposed to be made of an inorganic material such as a glass plate, or an organic material such as acrylic, polycarbonate, or acrylic. Guide grooves are essential for disk substrates in order to increase recording density and to perform tracking focusing servo reliably. For organic materials that can be cast or injection molded, use a metal stub bar with a guide groove formed during cast or injection molding.
The guide groove can be formed relatively easily. The above-mentioned recording material and protective dielectric film are placed on this organic disk substrate.
Alternatively, a dielectric film for increasing the Kerr rotation angle, a recording material, and a protective metal film or dielectric film are formed in vacuum using a multi-source sputtering device.

However, in a magneto-optical recording element using such an organic substrate, warping occurs due to stress and moisture absorption with the dielectric film even in a normal atmosphere. This warping deformation poses a major problem in terms of the operating characteristics of recording and reproducing devices. Furthermore, deformation due to rotational force during recording and reproduction cannot be avoided in the case of organic substrates. Furthermore, when placed under high temperature and high humidity conditions (e.g. 70℃RH90%), which is a guideline for long life and reliability, the recording material and dielectric film will peel off from the organic substrate due to hygroscopic expansion due to the large thermal expansion coefficient of the organic substrate. There are things to do.

On the other hand, although it is somewhat troublesome to form guide grooves on an inorganic glass substrate, it has a small coefficient of thermal expansion and there is no problem with moisture absorption, so magneto-optical recording elements using glass substrates can be used with organic substrates. It has an advantage in terms of reliability compared to the one used.

However, such a magneto-optical recording element using a glass substrate also has drawbacks in terms of safety and longevity, as the edges may chip during handling, for example.

[Purpose of the Invention] The present invention has been made in view of the above circumstances, and by bonding an organic substrate as a protective material to a glass disk substrate, it is possible to improve safety and ease of handling, and to extend the service life. The purpose of the present invention is to provide an inexpensive magneto-optical recording element that can be used.

[Summary of the Invention] The magneto-optical recording element of the present invention includes a donut-shaped glass disk substrate having a guide groove, and a magnetic material having an axis of easy magnetization in a direction perpendicular to the film surface formed on the disk substrate. and an organic substrate adhered to the inner and outer circumferential surfaces of the disk substrate and the magnetic film forming surface side.

[Embodiments of the invention] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a single-sided magneto-optical recording element according to an embodiment of the present invention, in which a magnetic film having an axis of easy magnetization in a direction perpendicular to the film surface is placed on a donut-shaped glass disk substrate having a guide groove. An organic substrate 12 is bonded with an adhesive 13 to the inner and outer circumferential surfaces of the recording medium 11 on which the magnetic film is formed and to the side on which the magnetic film is formed. In this case, the organic substrate 12 is formed to have a convex portion 14 protruding from the surface of the recording medium 11 on the outer peripheral surface side of the recording medium 11 .

The adhesive 13 is a U-curing resin or a low-temperature thermosetting resin, and the organic substrate 12 is an acrylic (PMMA) resin.
) or polycarbonate (P, C), etc., and can be mass-produced at low cost using an injection molding device to match the dimensions of the glass disk substrate.

As part of the recording medium 11 is shown in FIG. 3, a dielectric layer 16 is formed on a disk substrate 15 made of a donut-shaped unpolished glass plate having a guide groove to increase the Kerr rotation angle. be done. On this dielectric layer 16, a recording layer 17 made of a magnetic film having an axis of easy magnetization in a direction perpendicular to the film surface, such as a Tb--Co amorphous magnetic layer, is formed. A protective layer 18 made of a dielectric material such as SiO2 or 8iN is formed on this recording layer 17 to protect and seal the recording layer 17, and a reflective layer 19 made of a metal layer is formed on this protective layer 18 for reproduction. C by increasing the reflected light during reading
/N is formed for the purpose of improving. The recording medium 11 is constituted by the glass disk substrate 15 described above and the thin film layer formed by a plurality of vapor deposition or sputtering methods.

Next, the manufacturing process of the present invention will be explained.

The glass disk substrate 15 can be cut into a desired disk shape by processing a large sheet of thin glass into a predetermined outer circumferential line using a diamond cutter or the like, and then applying mechanical or thermal shock. Demand for thin glass materials for liquid crystal displays has increased in recent years, and a large number of thin glass materials with good flatness and few scratches on the surface are on the market.
It is best to choose a material with as little birefringence as possible from among them.

The plate thickness is selected depending on the diameter of the disk, but if the outer diameter is about φ120, 0.5 mm is sufficient, and if the outer diameter is about φ300 m, 1 m is sufficient for mechanical strength.

After this, it is necessary to perform a guide groove forming process using photolithography, so it is desirable to drill the inner peripheral hole after that, so it is convenient to carve a recess at the center position as a position mark.

In this case, even if the inner and outer circumferential machining is completed, subsequent steps are not necessarily impossible. However, it is easier to apply resist and clean it without inner peripheral holes.

Next, after cleaning and drying the circular glass disk, a resist is applied. Needless to say, this photo-etching process is simple and can use a silicon wafer process (jigs and equipment) if the disk diameter is about 75 to 150 m+.

After exposure and development using a mask with spiral or concentric guide grooves, fluorocarbon (CF4) or oxygen (02) gas is introduced or the resist is used as a block in active ion erasure (RIE). Guide grooves can be formed by etching. This guide groove has, for example, a pitch of 2 μ, a groove width of 1 μ, and a groove depth of about 0.1 μ, and can be formed in several minutes by RIE.

After forming the guide groove, the desired inner circumferential line is processed with a diamond cutter, the inside is cut out by thermal shock, etc., the resist is peeled off, and a dielectric layer 16 and a recording layer 17 are formed through a cleaning and drying process.
Formation of

For forming the recording layer 17, it is convenient to use a multi-source sputtering device with four or more sources or in-line type equipment.

A donut-shaped disk substrate 15 with a guide groove formed thereon is placed in a vacuum chamber, and once a sufficient degree of vacuum is reached, argon (Ar) gas is introduced at approximately 5 x 10' Torr using a normal magnetron sputtering method to form a SiN target. High frequency power is applied to form the dielectric layer 16 to a thickness of about 1,000. Next, high frequency power (direct current is also acceptable in the case of conductors) is applied to two targets, the Tb target and the Co target, to form an amorphous Tb--Co magnetic layer to a thickness of 500 mm. The composition ratio of Tb and CO can be controlled by the power input to each.
The amorphous Tb--Co1a layer formed on the N upper layer has an easy axis of magnetization perpendicular to the film surface.

The protection 1118 that protects and seals the recording layer 17 is then replaced again with S.
High frequency power is applied to the iN target and the dielectric film is
Form it to a thickness of about 100cm thick. Further, as a reflection 119 for reflecting the light that has passed through the recording layer 17, high frequency power is applied to an Af (aluminum) target, and an aluminum layer of >1,000 layers is formed by applying direct current to the Af (aluminum) target, thereby forming the recording medium 11.

The feature of the present invention is that the recording medium 11 formed in this way
is bonded with an adhesive 13 to an organic substrate 12 that integrally protects the magnetic film (recording H17) forming side and inner and outer peripheral surfaces, thereby increasing the safety, ease of handling, and long life of the magneto-optical recording element. It is to aim for.

In the embodiment shown in FIG. 1, the organic substrate 12 is designed to match the dimensions of a disk substrate 15 made of glass. The material is acrylic (PMMA) or polycarbonate (P, C
), etc., and can be mass-produced at low cost using an injection molding machine or the like. The surface of the disk can be protected by providing the convex portion 14 on the disk substrate 15 with the disk substrate 15 made of glass, which is formed thick at least on the outer periphery, bonded to the disk substrate 15 . In addition, the inner and outer peripheral surfaces of the glass disk substrate 15 are also adhesively fixed at the same time.
It is obvious at first glance that the glass disk substrate 15 is protected. A thickness of about 0.5 to 1jII is sufficient for protecting the side of the magnetic film on which the recording layer 17 is formed.

An example of a magneto-optical image recording element with a double-sided structure is shown in FIG.
~3 pairs of shoes. In FIG. 2, 11 is a recording medium, 13 is an adhesive, and 12 is an organic substrate.

A method for bonding the recording medium 11 of the magneto-optical recording element shown in FIG. 1 and the organic substrate 12 will be described in detail with reference to FIG. 4. That is, the organic substrate 12 is placed on the ultraviolet light incident window 21 of the vacuum chamber A partitioned by the silicone rubber partition wall 20, and a predetermined amount of the liquid UV curing resin adhesive 13 is dropped. The recording medium 11 having a small outer periphery is supported by a deformable Teflon jig 23 so as to be able to be positioned. B is a vacuum chamber.

The bonding procedure is as follows: (1) The vacuum chambers of both chambers A and 8 are evacuated at the same time to sufficiently degas the liquid UV curing resin.

(2) The vacuum chamber in chamber B is gradually returned to atmospheric pressure, and the organic substrate 12 and recording medium 11 are pressed together at atmospheric pressure via the silicone rubber partition wall 20.

■ Wait several minutes while pressing to make the adhesive 13 sufficiently thin and uniform.

■ UV light is irradiated from the ultraviolet incident window 21 to harden the adhesive 13 of the U-curing resin.

■Return the A quality to atmospheric pressure and take it out.

It is.

Note that in the embodiment shown in FIG. 2, the U2 curing resin cannot be used, so a thermosetting resin that hardens at a low temperature of 40 to 50 DEG C. may be used.

As explained above, a dielectric layer that increases the Kerr rotation angle, a recording layer, a dielectric protective layer, and a light reflective layer are formed on a glass disk substrate that has a small coefficient of thermal expansion and is not hygroscopic.
Furthermore, since an organic substrate is attached as a protective material, safety, ease of handling, and long life can be achieved. Glass disk substrates require only one photolithographic process without the need for polishing, but as explained above, they can be manufactured at high yields and at low cost.

[Effects of the Invention] As described above, according to the present invention, by bonding an organic substrate to a glass disk substrate as a protective material, safety and ease of handling can be improved, and the service life can be extended. An inexpensive magneto-optical recording element can be provided.

[Brief explanation of drawings]

1 is a cross-sectional view showing one embodiment of the present invention, FIG. 2 is a cross-sectional view showing another embodiment of the present invention, FIG. 3 is a cross-sectional view showing a part of the recording medium in FIG. FIG. 4 is a sectional view showing an example of a method for manufacturing the magneto-optical recording element shown in FIG. 11... Recording medium, 12... Organic substrate, 13...
Adhesive, 5... Disc substrate, 17... Recording layer.

Claims (2)

[Claims] (1) A donut-shaped glass disk substrate having a guide groove, a magnetic film formed on the disk substrate and having an axis of easy magnetization in a direction perpendicular to the film surface, and an inner and outer circumferential surface of the disk substrate, A magneto-optical recording element comprising: an organic substrate adhered to the surface on which the magnetic film is formed. (2) The magneto-optical recording element according to claim 1, wherein an organic substrate is used as the organic substrate, the outer peripheral surface of the disk substrate having a convex portion protruding from the surface of the disk substrate.