JPS62277642A - Optical information recording medium and its production - Google Patents

Abstract

PURPOSE:To enable the relatively easy formation of guide grooves by providing a guide groove layer which is formed on a flat substrate, consists of nitrocellulose and dye and has the guide grooves and a recording layer which is formed on said guide groove layer. CONSTITUTION:The thin guide groove layer 2 which has about 600-10,000Angstrom thickness and consists of the nitrocellulose and dye is formed on the substrate 1 consisting of a glass plate or org. resin plate and the spiral or concentrical guide grooves 7 are formed in said guide groove layer 2. A dielectric layer 3 consisting of Si3N4 is further formed as an enhancement layer and protective layer on the guide groove layer 2 and the recording layer 4 consisting of TbCo is formed on the dielectric layer 3. A dielectric layer 5 consisting of Si3N4 is formed as the enhancement layer and protective layer on the recording layer 4 and a reflective layer 6 consisting of Al is formed on the dielectric layer 5. The guide grooves 7 are thereby easily formed on any substrate 1 such as glass substrate or resin substrate; in addition, the depth, width, shape, etc., of the guide grooves 7 are easily controlled.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Purpose of the Invention (Industrial Application Field) This invention relates to an optical information recording medium that records, erases, or reproduces information using the thermal energy of light, and its use. Regarding the manufacturing method.

(Prior art and problems to be solved by the invention) In recent years, research and development of magneto-optical memory devices and optical phase change memory devices that are capable of high density, large capacity, and high speed access have been actively conducted in various fields. ing.

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

As a recording material for such a magneto-optical memory device, Tb
Co, GdCo% TbFe, GdT
Amorphous alloy thin films of rare earths and transition metals such as bFe and TbDyFe are suitable. This is because the amorphous alloy thin film of rare earths and transition metals has an axis that is easily magnetized in the direction perpendicular to the film surface, and because it is amorphous, there is no grain boundary noise, and the laser light required for recording is This is because it has an excellent property of being able to use less power. However, when an amorphous alloy thin film of rare earths 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, resulting in poor reproduction signal quality. There are drawbacks. In order to improve the quality of this reproduced signal, efforts have been made to increase the Kerr rotation angle by forming a dielectric film of S10, 513N4, or Ac on the recording material or between the substrate and the recording material. (e.g., published by the American Physical Society, Jo
urnalof Applied Physlcs M
o1.45. A 8. Aug@t 1974 No. 3
(See page 643).

Also, the disk substrate that forms the recording material may be an inorganic glass plate, an organic material such as acrylic or polycarbonate. Nate and epoxy have been proposed. For such a disk substrate, guide grooves are indispensable in order to have a high optical density and to perform tracking, focusing, and servo reliably. An organic material that can be cast or injection molded is a metal stamp 1 with a guide groove formed on it. Since guide grooves can be formed relatively easily during casting or injection molding using the method, it is considered to be the closest in practical terms. Then, the above-mentioned recording material and a dielectric film for retention, or a dielectric film for increasing the Kerr rotation angle, a recording material, and a metal film or dielectric film for retention are deposited on this organic disk substrate using a multi-source sputtering device. Form in vacuum using

However, in a magneto-optical biscythe element using such an organic disk substrate, warping occurs due to stress and moisture absorption with the dielectric film even in a normal atmosphere. This warping deformation is 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 disk substrates. Furthermore, under high temperature and high humidity conditions (e.g. 701: RH 90%), which is a measure of long-term life and reliability.
), the recording material and dielectric film may peel off from the organic disk substrate because the organic disk substrate has a large coefficient of thermal expansion and a large coefficient of hygroscopic expansion.

Also, injection molded acrylic or polycarbonate? Neato's organic disk substrate has the disadvantage that the birefringence changes greatly from the center to the outer circumference due to uneven flow and cooling of the injection material, making it unsuitable as an organic disk substrate for magneto-optical recording devices. I know something. On the other hand, epoxy organic disk substrates made by casting have a small birefringence, but have a disadvantage of being difficult to mass-produce.

On the other hand, glass substrates made of inorganic materials have a small coefficient of thermal expansion and do not have the problem of moisture absorption, but it is very troublesome to form guide grooves, and furthermore, manufacturing disk substrates by polishing is very expensive. . In addition, at least one side is optically polished, resist is applied and exposed using a mask with guide grooves, or after forming guide grooves with resist (using an exposure device equipped with a precise feeding mechanism and a laser), RI is applied.
It is necessary to form guide grooves one by one by etching the glass using an E (reactive ion etching) device, which poses a problem in that it is not suitable for mass production.

However, on the other hand, the coefficient of thermal expansion is small and there is no hygroscopicity. Sickle elements have the advantage of long life.

Several proposals have been made so far as methods for easily forming guide grooves (Japanese Patent Application Laid-Open No. 59-171046, 59-229748, 59-215035,
No. 59-215036, No. 59-215037, No. 59-203255, etc.). Of these, JP-A-59-17
No. 1046 discloses that a pigmented film that absorbs visible light and deforms is formed on a substrate, a reflective film for recording information is laminated on top of the pigmented film, and then a visible light laser is used to deform the pigmented film and the reflective film to form guide grooves. It forms the With the above structure, it is possible to suppress the occurrence of defects that occur when forming the stun plate 9 and forming a substrate with a guide groove. In JP-A-59-171046, in a writable optical information recording medium, only the reflective layer is deformed together with the guide groove layer. However, since magneto-optical recording media and phase change recording media usually have a multilayer structure including dielectric layers, it is difficult to form guide grooves neatly using the above method. In other words, the groove width,
It is difficult to control parameters such as groove depth. Furthermore, since the multilayer film structure on the guide groove layer including the recording layer is deformed, damage during formation of the guide groove becomes a problem.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide an optical information recording medium in which guide grooves can be formed relatively easily, and a method for manufacturing the same.

[Structure of the Invention] (Means for Solving the Problems) This invention forms a guide groove layer having guide grooves on a flat substrate using a material made of nitrocellulose and a dye, and It is an optical information recording medium with a recording layer provided on the layer.

This invention also includes a step of forming a thin guide groove layer with a thickness of about 600 to about 100,000 mm on a flat substrate, and then irradiating the guide groove layer with a laser beam to form a spiral or spiral shape. This method of manufacturing an optical information recording medium includes a step of forming concentric guide grooves of a predetermined depth, and a step of providing a recording layer on the guide groove layer after this step.

(Function) According to the present invention, a guide groove can be easily formed on any substrate such as a glass substrate or a resin substrate, and the depth, width, shape, etc. of this guide groove can be easily controlled. . There is also a possibility that the width of the guide groove and the groove interval can be narrowed.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. That is, the optical information recording medium of the present invention has the first
It is constructed as shown in the figure, and numeral 1 denotes a flat substrate, for example, a glass plate or an organic resin plate. On such a substrate 1, a thin guide groove layer 2 having a thickness of about 600X to about 10,000X and made of nitrocellulose and one dye is formed, and in this guide groove layer 2, a guide groove layer 2 is formed by a method described later. , a spiral or concentric guide groove 7 is formed. Note that although this guide groove 2 appears convex in the diagram, in actual use,
Since the laser beam is irradiated from the substrate 1 side, the grooves are concave when viewed from the substrate 1 side.

Furthermore, a dielectric layer 3 made of, for example, 513N4 is formed on the guide groove layer 2 as an enhancement layer and a protective layer, and a recording layer 4 made of, for example, TbCo is formed on this dielectric layer 3.
is formed. On this recording layer 4, a dielectric layer 5 made of 813N4, for example, is provided as an enhancement layer and a protective layer.
is formed, and a reflective layer 6 made of a metal such as At is formed on this dielectric layer 5.

In the above case, the dye includes N-oxyethylaniline, N-ethyl-N-oxyethylaniline, dimethylaniline, which has a low absorption coefficient in the laser wavelength range used for recording, reproducing, and erasing of optical information recording media. A β-naphthol dye or the like is preferable, but a dye or an inorganic dye may be used as long as the guide groove 7 can be formed by irradiation with a laser beam for forming the guide groove 7.

Next, a method for manufacturing the optical information recording medium having the above structure will be explained. First, nitrocellulose and the dye N-ethyl-N are placed on a flat substrate 1 made of glass, for example.
-oxyethylaniline in an organic solvent (e.g. xylene)
The guide groove layer 2 is formed by dissolving and filtering the solution into a thickness of 100 OX using a spin code method.

Next, this guide groove layer 2 is baked at about 80° C. for about 20 minutes to evaporate the organic solvent, and then the cooled layer is irradiated with laser light using a laser exposure machine to form spiral grooves 8. By drilling, the depth is approximately 7 mm when viewed from the board 1 side
001. A guide groove 7 having a width of about 850×1 and a track pitch of 1.6 μm is formed in a spiral shape.

Next, on this guide groove layer 2, a dielectric layer 3, Si
, N4 layer at 1500X, recording layer 4 (TbCo)8 at 250X, dielectric layer 5 (3N4 layer) at 1000X,
The reflective layer 6 is formed by sequentially stacking At layers of 1500×.

In this case, the 513N4fl and At layer d are an enhancement layer and a reflective layer for increasing the Kerr rotation angle (θk), respectively. Further, the dielectric layer 3 also serves as a protective layer for the guide groove 7 as described above.

Further, as in the above embodiment, in order to improve the durability of the guide groove 7, a transparent dielectric layer 3, for example 51, is provided on the guide groove layer 2.
02.5tO1At203, S i , N4, AtN
.

It is ideal to form a metal oxide such as ZnS, metal nitride, or metal sulfide, but in this case, it is effective if the thickness of the dielectric layer 3 is 300X or more.

Usually, in a medium for magneto-optical recording and optical phase change recording, a structure is adopted in which a dielectric layer is provided on at least one of the upper and lower sides of the recording layer 4 in order to improve the Kerr rotation angle and suppress thermal deformation, respectively. ing. Therefore, we adopted a multilayer structure as described above, and formed a dielectric layer 3 with a thickness of 300X or more on the guide groove layer 2.
Providing this is effective in terms of durability.

Further, when recording, reproducing, and erasing are performed by irradiating the guide groove 7 with a laser beam from the substrate 1 side during use, it is desirable that the material of the guide groove layer 2 has a small absorption coefficient for the laser beam.

Furthermore, although the guide groove 7 is spiral in the above embodiment, it may be formed concentrically.

Moreover, in the above embodiment, only the guide groove 7 was formed.
Needless to say, from the gist of the present invention, it can be easily inferred that not only guide grooves but also glyph format information is formed.

[Effects of the Invention] According to the present invention, the guide groove 7 can be easily formed on any substrate 1 such as a glass substrate or a resin substrate, and the depth, width, shape, etc. of the guide groove 7 can be easily changed. It can be controlled. There is also a possibility that the width of the guide groove 7 and the groove interval can be narrowed.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a dual optical information medium and a method of manufacturing the same according to an embodiment of the present invention. 1... Substrate, 2... Guide groove layer, 3... Dielectric layer,
4... Recording layer, 5... Dielectric layer, 6... Reflective layer,
7... Guide groove.

Claims (2)

[Claims] (1) At least a flat substrate, a guide groove layer formed on the substrate with a thickness of about 600 Å to about 10,000 Å and made of nitrocellulose and a dye and having guide grooves, and a guide groove layer formed on the guide groove layer. What is claimed is: 1. An optical information recording medium comprising: a recording layer comprising a recording layer; (2) On a flat substrate, the thickness is approximately 600 Å to approximately 1000 Å.
a step of forming a thin guide groove layer of 0 Å, and a step of irradiating the guide groove layer with a laser beam after this step to form a guide groove of a predetermined depth in a spiral or concentric pattern; A method for manufacturing an optical information recording medium, comprising the following steps: forming a recording layer on the guide groove layer.