JPH03207036A - Glass substrate for optical memory element and production thereof - Google Patents

Abstract

PURPOSE:To prevent the nonuniform spreading of a resin for protection at the time of dropping by forming concentrical grooves in the inner peripheral position than a recording medium layer on the surface side of the glass substrate where the recording medium layer is formed. CONSTITUTION:The guide track grooves for guiding a light beam and guide address grooves 5a are provided on the glass substrate 5. The concentrical grooves 5b are provided in the peripheral position inner than the grooves 5a and in the positions nearer toward the outside of the position where a center hub is adhered. The recording medium layer 6 is formed to cover the grooves 5a on the substrate 5 and occupies the intervening regions up to the grooves 5b on the inner peripheral side. The protective layer 7 is formed by applying a UV resin by a spin coating method on the grooves 5b as the start point on the inner peripheral side then toward the outer side and curing the coating by irradiation with UV rays. The dropped resin flows along the grooves 5b by surface tension and does not, therefore, flow to the inner side thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glass substrate for an optical memory element that optically records, reproduces, erases, etc. information, and a method for manufacturing the same.

[Conventional technology]

In recent years, optical memory devices have been actively researched and developed as high-density, large-capacity memory devices. The substrate material for optical memory devices is generally glass, polycarbonate,
Acrylic etc. are used. Among them, glass, which has the best optical properties, mechanical properties, and moisture absorption/permeability properties, is attracting attention as a substrate for optical memory devices.

The single-plate optical memory element using the above-mentioned glass substrate is mainly composed of a glass substrate 1, a recording medium layer 2, and a protective resin N3, as shown in FIG. 5, for example. Note that the recording medium layer 2 described above is provided on the glass substrate 1, and the protective resin M3 is provided on the recording medium layer 2. The protective resin layer 3 is formed on the recording medium layer 2.
It is designed to protect.

The glass substrate 1 has guide track grooves and guide address grooves 1a (for convenience in the figure) for guiding a light beam irradiated to a predetermined position when recording, reproducing, erasing, etc. information on an optical memory element. ) is formed (indicated by a thick solid line). Note that, for example, in the case of a magneto-optical memory element, the recording medium layer 2 has a multilayer structure in which a transparent dielectric film, a rare earth transition metal alloy thin film, a reflective film, etc. are laminated.

On the other hand, the protective resin layer 3 plays important roles such as preventing scratches, dust, etc. from adhering to the recording medium layer 2, and preventing oxidation of the recording medium layer 2. As the material for the protective resin layer 3, ultraviolet-curable citrus resin (hereinafter referred to as UV resin) is often used because it is advantageous in terms of workability, process time, and the like. The protective resin N3 is mainly formed by a subin coating method. That is, the protective resin layer 3 is formed by applying the above-mentioned U2 resin onto the recording medium layer 2 and then curing the U2 resin by irradiating ultraviolet rays.

[Problem to be solved by the invention]

However, as mentioned above, when coating the protective resin layer 3 with the U resin by the Subin coating method, UV rays are applied to the inner peripheral position than the area where the recording medium layer 2 is formed.
The resin is dropped and the spinner is rotated at a rotation speed that provides the desired film thickness. In this case, the shape of the protective resin layer 3 after coating becomes an irregular shape, as shown in FIG. 6, for example, and is not concentric with the glass substrate l.

Therefore, a problem arises in that the shape of the protective resin layer 3 varies greatly among manufactured optical memory elements.

By the way, in an optical memory element, as shown in FIG. 7, the center of the hole provided at the center of the glass substrate 1 and the center of the guide track groove and the guide address groove la are generally eccentric. In some cases, a jig called a center hub 4 is bonded to absorb the light and to attach the optical memory element to the rotating spindle of the drive device. When bonding the center hub 4 to the glass substrate 1, the presence of the protective resin layer 3 in an uneven state in the bonding area is a problem that can occur between the glass substrate 1 and the center hub 1.
This has problems such as disturbing the parallelism between the two and having an adverse effect on adhesive strength and reliability.

[Means to solve the problem]

In order to solve the above-mentioned problem, a glass substrate for an optical memory element according to the invention of claim 1 is provided, in which the above-mentioned recording medium layer is It is characterized by having grooves formed concentrically on the side where the recording medium layer is formed, and further on the inner circumferential position of the area where the recording medium layer is formed.

In addition, in order to solve the above problem, the method for manufacturing a glass substrate for an optical memory element according to the invention of claim 2 uses a dry etching method when forming guide track grooves and guide address grooves for guiding a light beam. It is characterized in that the concentric grooves are formed at the same time.

[For production]

In the structure of the invention as claimed in claim 1, since the concentric grooves are formed at the inner peripheral position of the area where the recording medium layer is formed, the protective resin for the recording medium is applied by spin coating. During application, the dropped protective resin flows along the grooves due to its surface tension. Therefore, the dropped resin does not flow toward the inner periphery of the concentric grooves.

This makes it possible to prevent the protective resin from spreading non-uniformly which occurs when the protective resin is dropped, so that it is possible to form a protective resin layer that is uniform and reproducible even after one rotation of the spinner.

In the invention of claim 2, the concentric grooves are formed by dry etching at the same time as the guide track grooves and the guide address grooves are formed, so manufacturing costs can be reduced and manufacturing process improvements can be made. Loss can be significantly reduced.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 to 3.

An optical memory element using a glass substrate for an optical memory element according to the present invention mainly includes a glass base Fi5, a recording medium layer 6, a protective resin layer 7, as shown in FIGS. 1(a) and 1(b), for example.
and a center hub 8. The recording medium N6 described above is provided on the glass substrate 5. A protective resin layer 7 made of an ultraviolet curable resin (hereinafter referred to as UV resin) is provided on the recording medium layer 6. Further, the center hub 8 is bonded so as to fit into the center hole of the glass substrate 5.

A guide track groove and a guide address groove 5a (indicated by thick solid lines in the figure for convenience) are provided on the glass substrate 5 for guiding the light beam emitted from an optical head (not shown), and further A concentric groove 5b according to the present invention is provided at an inner peripheral position than the guide truss groove and the guide address groove 5a, and at a position closer to the outer side than the bonding position of the center hub 8.

The recording medium layer 6 is formed so as to cover the guide l/rasok groove and the guide address groove 5a on the glass substrate 5, and the area shown in the figure up to the concentric groove 5b toward the inner circumference, The outer peripheral side extends to the illustrated region up to the outer end of the glass substrate 5.

The recording medium layer 6 has a multilayer structure, and includes, for example, a first transparent dielectric film, a rare earth transition metal alloy thin film, a second transparent dielectric film, and a metal reflective film (these thin films) sequentially from the glass substrate 5 side. (not shown) are layered.

The above-mentioned protective resin layer 7 is provided by applying a UV resin to an area outside of the concentric groove 5b as a starting point on the inner circumferential side using a spin coating method, and then curing it by irradiating ultraviolet rays.

Here, the first manufacturing method of the above-mentioned optical memory element will be explained as follows.

When manufacturing an optical memory element, first, a glass substrate 5 is prepared. The glass substrate 5 usually has a desired shape by processing the inner and outer diameters of a plate-shaped glass.

At this time, if necessary, surface polishing and strengthening treatment are performed before manufacturing. However, the concentric grooves 5b according to the present invention are formed at the time of manufacturing the glass substrate 5, for example, in parallel with the inner and outer diameter processing. Note that the shape of the concentric groove 5b is V
The shape is not particularly limited, and may be a letter shape, a U shape, or a rectangle.

Next, at the stage of manufacturing the substrate, guide track grooves and guide address grooves 5 are formed by dry etching on the glass substrate 5 on which the concentric grooves 5b have been formed.
Precept the form of a.

The formation of the guide trunk groove and the guide address groove 5a is performed in the second step.
The details will be explained below based on the figures.

First, as shown in FIG. 2(a), a resist N9 (indicated by hatching for convenience) is coated on the side of the glass substrate 5 on which the concentric grooves 5b are formed by a subin coating method. do.

Then, as shown in FIG. 2(b), a laser cutting exposure method or a contact exposure method using a photomask is used to obtain a desired pattern of guide track grooves and guide address grooves 5a on the resist layer 9. , the resist is exposed and developed to form a pattern.

Next, as shown in FIG. 2(C), the glass substrate 5 on which the patterns of the guide track grooves and the guide address grooves 5a are formed is subjected to a glass dry etching process using a dry etching device. Actual guide track grooves and guide address grooves 5a are formed on the glass substrate 5.

Then, as shown in FIG. 2(d), by removing the residual resist by unsinging, cleaning, etc., desired guide track grooves and guide address grooves 5a are obtained.

A recording medium layer 6 is formed by sputtering on the guide track grooves and guide address grooves 5a formed as described above, and then the process moves on to forming a protective resin layer 7.

Here, the process of forming the protective resin layer 7 will be explained based on FIG. 3 as follows.

First, after mounting the glass substrate 5 on the subinner rotary table 13, as shown in FIG.
An arbitrary amount of UV resin IO is dropped at a position on the glass substrate 5 slightly outside the position where b is provided. UV resin 10
When dropping, the droplet may be fixed while slowly rotating the glass substrate 5, or conversely, the droplet may be moved in the circumferential direction and dropped.

The UV resin 10 dropped in this way is shown in FIG.
), the surface tension creates concentric grooves 5b.
It spreads along the concentric groove 5b without flowing inward.

Next, if the spinner-rotary table l3 is rotated at an arbitrary rotation speed from the above state, as shown in FIG. 3(c),
UV resin 0 is formed starting from the concentric groove 5b.

Then, as shown in FIG. 3(d), by irradiating ultraviolet rays from above, the U resin is cured and a protective resin layer 7 is formed.

Finally, the center hole 8 provided to reduce eccentricity between the center hole of the glass substrate 5 and the guide trunk groove and guide address groove 5a is adhered onto the glass substrate 5 with adhesive or double-sided tape. An optical memory device according to the present invention is obtained.

As described above, according to this embodiment, the U resin 10 dropped onto the glass substrate 5 does not flow inward from the concentric grooves 5b due to the surface tension in the concentric grooves 5b. Therefore, the protective resin layer 7 is formed uniformly on the glass substrate 5 with good reproducibility, so that a high quality optical memory element can be manufactured.

The second method for manufacturing a glass substrate for an optical memory element according to the present invention will be explained below with reference to FIG.

In the first manufacturing method described above, the concentric grooves 5b were provided in advance at the manufacturing stage of the glass substrate 5.

In the second manufacturing method disclosed herein, concentric grooves 5b
The manufacturing method differs from the first manufacturing method described above in that the formation of the guide track grooves and the guide address grooves 5a is performed in parallel with the formation of the guide track grooves and the guide address grooves 5a using a dry etching method. A detailed explanation is given below.

First, a glass substrate 11 is prepared which has only been subjected to inner and outer diameter processing in the conventional manner.

Next, as shown in FIG. 4(a), a resist layer 12 (shown by hunting for convenience) is formed on the glass substrate 11 in the same manner as in the first manufacturing method. At this time, the coating start point on the inner peripheral side of the resist layer 12 is set to be inside the region where the concentric grooves 5b are to be obtained.

Next, by a laser cutting exposure method or a contact exposure method using a photomask, the guide track groove and the guide address groove 5a are formed in the same manner as in the first manufacturing method described above.
At this time, as shown in FIG. 4(b), the concentric grooves 5b (shown by cross-hatching for convenience) are also exposed at the same time. At this time, if a laser cutting exposure method is used, it is sufficient to simply change the exposure radius position, or if a contact exposure method using a photomask is used, a pattern is formed on the photomask in advance. Just leave it there.

Next, as shown in FIG. 2(b), a laser cutting exposure method or a close contact using a photomask is used to obtain a desired pattern of guide track grooves and guide address grooves 53 on the resist layer 9. Using the exposure method, the resist is exposed, developed, and the pattern formed.

Next, in the same manner as in the process shown in the first manufacturing method, the glass substrate l1 on which the patterns of the guide trunk groove and the guide address groove 5a and the pattern of the concentric grooves 5b are formed is dried. Using an etching device, the glass is dry-etched to create actual guide track grooves and guide address grooves 5 on the glass substrate 11.
a and the concentric groove 5b.

Then, the remaining resist is removed by ashing, cleaning, etc. After this, a desired glass substrate for an optical memory element is obtained through the same manufacturing steps as in the first manufacturing method.

According to the second manufacturing method, the glass substrate 1
It is not necessary to process the concentric grooves 5b in 1. Furthermore, the concentric grooves 5b are formed simultaneously when the guide track grooves and the guide address grooves 5a are formed. Therefore, manufacturing costs can be reduced, and process losses in the manufacturing method can be reduced.

Dimensions of each part of the optical memory element in the first and second methods of manufacturing a glass substrate for an optical memory element disclosed above,
For example, the outer diameter is 86 mm and the center hole diameter is 15 mm.
mm, the thickness of the glass substrate 5 is 1.2 m, and the range of the guide track grooves and guide address grooves 5a is set to 40 InIl1 to 82 mm. In addition, the glass substrate 5 (or glass substrate 1
When the outer diameter of the adhesive part to 1) is 22 mm, the formation area of the recording medium layer 6 is preferably 36 mm to 84 mm,
Therefore, the shape position of the concentric groove 5b is in the range of 22 mm to 36 mm, preferably 24 mm to 36 mm.
The position is within the range of 0.

Further, the shape and dimensions of the concentric grooves 5b are determined by, for example, cutting when the glass substrate 5 is manufactured in parallel with the inner and outer diameter machining, as shown in the first manufacturing method. Preferably, the width of the groove is 0.5 mm to 2.0 mm, and the depth of the groove is 0.1 mm to 0.2 mm. At this time, the shape of the groove may be a ■-shape, a U-shape, or a rectangle, but the shape is not particularly limited.

Further, concentric grooves 5 formed by the second manufacturing method
b is formed by the try etching method at the same time as the shape of the guide track groove and the guide address groove 5a, so the shape and dimensions of the groove are different from the first manufacturing method. The depth of the groove is about the same as 5a, that is, 0.04 μm to 0.10 μm, which is extremely shallow. Therefore, it would be meaningless to form the groove width in the same order as the guide track groove and the guide address groove 5a, that is, around 1 μm. degree is preferred. Further, even in this case, the shape of the groove is not particularly limited.

[Effects of the Invention] As described above, the glass substrate for an optical memory element according to the invention of claim 1 has a surface on which the recording medium layer is formed, and which is inner than the area where the recording medium layer is formed. It has a structure in which concentric grooves are formed at circumferential positions.

Therefore, the protective resin does not spread non-uniformly when it is dropped, and moreover, it becomes concentric, so that the shape of the manufactured optical memory elements does not vary. Therefore, the protective resin layer can be formed on the glass substrate uniformly and with a beautiful appearance, resulting in the effect that an optical memory element of high quality and high commercial value can be obtained with good reproducibility.

Further, as described above, in the method for manufacturing a glass substrate for an optical memory element according to the invention of claim 2, in parallel with the formation of the guide track groove and the guide address groove for guiding the light beam,
The concentric grooves are formed by dry etching.

Therefore, the concentric grooves can be formed using the dry enoching method at the same time as the guide track grooves and guide address grooves are formed, so manufacturing costs can be reduced and losses in the manufacturing process can be reduced. This has the effect that it can be reduced.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention. FIG. 1(a) is a plan view showing a schematic structure of an optical memory element using a glass substrate according to the present invention. FIG. 1(b) is a sectional view of an optical memory element using the glass substrate shown in FIG. 1(a). FIG. 2 is a diagram showing a step of forming guide track grooves and guide address grooves on a glass substrate in advance by dry etching. FIG. 3 is a diagram showing a step of forming a protective resin layer after forming a recording medium layer on a glass substrate by a sputtering method. FIG. 4 is a diagram showing a process of forming concentric grooves by dry etching. 5 to 7 show conventional examples. FIG. 5 is a diagram showing a schematic structure of a conventional optical memory element. FIG. 6 is a diagram showing the shape of the protective resin layer after UV resin application when forming the protective resin layer. FIG. 7 is a diagram showing a state in which the center hub is adhered to a glass substrate. 5 is a glass substrate, 5a is a guide track groove and a guide address groove, 5b is a concentric groove, 6 is a recording medium layer, and 7 is a protective resin layer.

Claims (1)

[Scope of Claims] 1. In a glass substrate used for an optical memory element having an area on which a recording medium layer is formed, the surface side on which the recording medium layer is formed is the side on which the recording medium layer is formed. 1. A glass substrate for an optical memory element, characterized in that a concentric groove is formed at an inner peripheral position of the region. 2. The optical memory element according to claim 1, wherein the concentric grooves are formed by dry etching in parallel with the formation of the guide track grooves and guide address grooves for guiding the light beam. A method for manufacturing a glass substrate for