JPH0278040A - Production of substrate for information recording medium and substrate produced by this method - Google Patents

Abstract

PURPOSE:To produce a substrate for information recording medium of desired characteristics with good mass-productivity and at a low cost by forming a latent image on a photosensitive resin film provided on a substrate by selectively exposing and then developing the film to form a pattern of photosensitive resin on the substrate. CONSTITUTION:A solution containing at least either a hydrolysate of silicon alkoxide or a hydrolysate of metal alkoxide is mixed with a photo-sensitive resin solution, and the mixture is applied on a transparent substrate 2 having a through hole 1 to form the photosensitive resin film 3. Then the resin film 3 is irradiated with UV light 5 to form the latent image 3l by selectively exposing through a photomask 4. The resin film with the latent image formed is then developed to form photosensitive resin pattern 3a on the substrate 2. By this method, the production processes are simplified, which realizes low-cost mass production. The obtained guide grooves 6 have flat bottoms 6a. Thus, the substrate having excellent heat resistance and durability can be obtained with mass-productivity at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a substrate used in an information recording medium such as a magneto-optical recording medium or an optical recording medium, and a substrate obtained by this method.

[Conventional technology]

In information recording media such as magneto-optical recording media and optical recording media, when storing information on these recording media or reading information recorded on these recording media, the capturing means or reading means is the recording medium. In order to accurately scan (track) a predetermined part of the recording medium, the substrates that make up these recording media are used that have a concave-convex pattern (hereinafter referred to as "guide groove") formed on the surface in advance. It is being

Conventionally, there have been two methods for manufacturing an information recording medium substrate having such a guide groove, for example, as described below.

The first method is called the direct etching method, in which a resist film (g photosensitive resin f11) is formed on the surface of the glass substrate.
m>, a latent i corresponding to the guide groove is formed on the resist film by means such as laser cutting (exposure with laser light), and then the resist film with the latent image formed thereon is developed to form a resist. A substrate for an information recording medium in which guide grooves are formed on the surface of the glass curtain plate is obtained by forming a pattern, dry etching the glass substrate with a resist pattern, and then peeling off the resist pattern. (For example, JP-A-59-2
(See Publication No. 10547). □The second method is the so-called 2P method, which uses a mold (hereinafter referred to as "stamper") with a pattern of protrusions and recesses corresponding to the guide grooves formed on the surface.
”.

), a liquid photosensitive resin (photopolymer) is placed on the surface of the stamper, and then a glass substrate is pressed onto the surface of the stamper for stamping, so that the photosensitive resin is sandwiched between the glass substrate and the stamper. This photosensitive resin completely fills the uneven pattern of the stamper and adheres uniformly to the surface of the glass substrate, and then ultraviolet rays are irradiated from the back side of the glass substrate to coat the photosensitive resin. After the stamper is cured, the stamper is peeled off to obtain a two-layer structure substrate for an information recording medium in which the cured resin having a concavo-convex pattern is adhered to the surface of the glass substrate.

[Problem to be solved by the invention]

However, in the first method (direct etching method), the guide groove is formed by etching the glass substrate, but at that time, it is difficult to make the etching speed uniform for the etched part, so the bottom surface of the guide groove is made smooth. In addition, laser cutting, development,
The dry etching process has to be carried out sequentially, and the equipment for carrying out these processes is expensive, resulting in a significant disadvantage in terms of workability and production cost.

In addition, the second method (2P method) is used to improve the heat resistance, hardness, durability, adhesion between the glass substrate and the cured resin on which the uneven pattern is formed, and the stamper properties of the obtained information recording medium substrate. In recent years, when there is a demand for a dramatic increase in recording density, it is not always easy to obtain a high-quality substrate for information recording media that can meet the demand for a dramatic increase in recording density. ing. Another drawback is that it takes time and money to produce the stamper.

Therefore, it is an object of the present invention to overcome the drawbacks of the above-mentioned prior art,
A method for manufacturing a substrate for an information recording medium, which makes it possible to obtain a substrate for an information recording medium that satisfies various properties required of the substrate for an information recording medium with good mass production at a low cost, and an information recording medium obtained by this method. Our objective is to provide substrates for media.

[Means to solve the problem]

The present invention has been made to achieve the above object, and the method for manufacturing a substrate for an information recording medium of the present invention contains at least one of a silicon alkoxide hydrolyzate and a metal alkoxide hydrolyzate. A mixed solution of a solution and a photosensitive resin liquid is applied onto a substrate to form a photosensitive resin film, and then the photosensitive resin film is selectively exposed to light to remove the photosensitive resin. A latent image is formed on the film, and then
The method is characterized in that the photosensitive resin film on which the latent image is formed is subjected to a development treatment to form a photosensitive resin pattern on the substrate.

Further, the information recording medium substrate of the present invention is characterized in that the photosensitive resin pattern obtained by the method described above is formed on the substrate.

[Effect]

According to the conventional direct etching method, a resist film (photosensitive resin film) provided on a glass substrate is laser cut, and then developed to obtain a resist pattern, and then the substrate with the resist pattern is dry etched. an information recording medium in which guide grooves are formed by the glass pattern by etching the glass substrate in a portion where the resist pattern does not exist to a predetermined depth to form a glass pattern, and then peeling off the resist pattern. However, according to the method of the present invention, a photosensitive resin film provided on the substrate is selectively exposed to light to form a latent image on the photosensitive resin film, and then,
A photosensitive resin pattern is formed on the substrate by developing the photosensitive resin film on which the latent image has been formed, eliminating the need for dry etching and resist pattern peeling in the direct etching method, simplifying the process and facilitating mass production of products. and cost reductions are achieved. Furthermore, according to the direct etching method, since the glass substrate is etched,
It has been difficult to make the bottom surface of the guide groove smooth, but according to the method of the present invention, the surface of the glass substrate that has been polished in advance to increase the surface smoothness, that is, to reduce the surface roughness, or Since the surface of the plastic substrate with high surface smoothness can be used as the bottom surface of the guide groove, accurate tracking is possible in the information recording medium.

Furthermore, according to the conventional 2P method, in order to form the guide grooves, it is necessary to stamp with a stamper whose surface has a pattern of protrusions and recesses corresponding to the guide grooves, and the production of this stamper requires cost and time. However, the method of the present invention has the advantage that, when forming a photosensitive resin pattern used for forming guide grooves, for example, a photomask, which is easier to produce and cheaper than the stamper described above, can be used. It is excellent.

In addition, in the 2P method, the thickness of the photosensitive resin between the glass substrate and the stamper must be increased from several micrometers to several tens of micrometers, so the gas generated when the photosensitive resin is cured is It is easily occluded in the resin, leading to a decrease in the physical properties of the cured resin (e.g. hardness, durability, etc.), and the adhesion between the glass substrate and the cured resin is reduced due to the occluded gas being released to its contact parts. However, according to the method of the present invention, the thickness of the photosensitive resin film can be reduced, so the above-mentioned two
No problems arise with the P method.

〔Example〕

(Example 1) Hereinafter, Example 1 of the present invention will be described with reference to FIG.

First, a glass disk made of soda lime glass (outer diameter 130 Mφ, inner diameter 15. After being immersed for 8 hours and subjected to chemical strengthening treatment, this was exposed to hexamethyldisilazane vapor in the atmosphere to undergo silazane treatment to form a translucent substrate 2 (surface roughness = 40 people) having a through hole 1 in the center. Obtained. Next, tetraethoxysilane (Si(OCHs)a), water, and ethyl cellosolve acetate were mixed in a ratio (mole ratio) of 1:2:5 to prepare a solution containing a hydrolyzate of silicon alkoxide, Next, this solution was mixed with a photosensitive resin liquid consisting of a novolac positive type photoresist (AZ-1350 manufactured by Hoechst Co., Ltd.) at a ratio (volume ratio) of 1:4 to prepare a mixed solution. Here, the solution containing the hydrolyzate of silicon alkoxide described above contains, in addition to the hydrolyzate, a partial hydrolyzate of silicon alkoxide, a polymer of a silicon compound, a trace amount of silica, and the like.

Then, the above-mentioned mixed solution is applied to the upper surface of the transparent substrate 2 by a spin code method, and the photosensitive resin film 3 (thickness:
100 people) was formed on a transparent substrate 2 (see Fig. 1(a)
)reference).

Next, the photosensitive resin film 3 is exposed using an ultraviolet contact exposure method using a photomask 4 having a pattern corresponding to the guide groove of the information recording medium substrate to be finally obtained and ultraviolet rays 5.
Selectively exposed latent image 3f corresponding to the guide groove! was formed on the photosensitive resin film 3 (see FIG. 1(b)).

Next, the photosensitive resin film 3 on which the latent image 3L has been formed is developed using a predetermined developer (a solution prepared by diluting AZ exclusive gay berotuba twice with water), washed with water, and dried to form a photosensitive resin film. After obtaining the pattern 3a, heat treatment is performed for 30 minutes at 150'C in the air using a clean oven to form the guide groove 6 formed by the photosensitive resin patterns 3a, 3a and the transparent substrate 2 between them. An information recording medium substrate of the present invention having the following properties was obtained (see FIG. 1(C)).

Note that the cross-sectional shape of the photosensitive resin pattern 3a formed on this substrate was compared before and after heat treatment, and the pattern 3a is thermally stable because it contains a silicon compound, and its shape does not change. Therefore, the cross-sectional shape of the guide groove does not change before and after the heat treatment, and the guide groove 6 having a predetermined shape is formed.

Next, silicon was used as a target and Ar was used as a reactive gas on the information recording medium substrate with guide grooves obtained in this example.
By reactive sputtering using a mixed gas of N2 and N2 (Δr/N2=2/1), a pressure of 10 m Torr, and a high frequency power of 1 KW, a transparent underlayer consisting of a silicon nitride film with a thickness of 800 mm was first formed. On top of that, TbFeCo as a target, Δr as a gas, 10 mrorr as a pressure, 0.5 as a high frequency power.
Next, a magnetic layer consisting of a terbium-iron-cobalt film with a thickness of 1000 nm is formed by a sputtering method using a terbium-iron-cobalt film with a thickness of 1000 nm, and on top of that, silicon is used as a target and a mixed gas of Ar and N2 (Ar/N2 is used as a reactive gas). N2=
2/1), by a reactive sputtering method using a pressure of 10 m Torr and a high frequency power of 1 KW.
A protective film layer consisting of a silicon nitride film having a thickness of 2000 was formed to obtain a magneto-optical recording medium having a magneto-optical recording film consisting of these three layers.

Regarding the obtained magneto-optical recording medium, in order to examine the adhesion between the information recording medium substrate with guide grooves and the magneto-optical recording film provided thereon, sulfide tape (trade name of tape manufactured by IJ3M, Inc., USA) was used. After pasting, I peeled it off and did a beer test, but no peeling occurred. Further, the magneto-optical recording medium was heated at a temperature of 25° C. on the low temperature side and 150° C. on the high temperature side.
℃, holding time 1 hour each, atmosphere temperature increase/decrease rate 50℃/
Heat cycle test under conditions of 100 minutes (number of cycles = 100
After conducting the above-mentioned beer test, it was found that the film did not peel off, was stable against heat, and had sufficient heat resistance.

It has also been found that the magneto-optical recording and reproducing properties of the magneto-optical recording medium thus obtained are equal to or better than those of the magneto-optical recording medium using a substrate obtained by the conventional direct etching method. Further, the bottom surface 6a (see FIG. 1(C)) of the guide groove 6 of this magneto-optical recording medium is a photosensitive resin pattern 3a.

It is constituted by the surface portion of the transparent substrate 2 between 3a,
In addition, since the substrate 2 has a small surface roughness, that is, a high surface smoothness, its bottom surface 6a is extremely smooth, and therefore, in this magneto-optical recording medium, the diffused reflection of the irradiated light is prevented and accurate tracking is performed. be able to.

As explained above, according to this example, compared to the conventional direct etching method, dry etching and resist pattern peeling are not required, so the process is simplified, and the bottom surface of the guide groove is smooth. A substrate can be obtained. In addition, in the conventional 2P method, as mentioned above, a stamper is used to obtain a substrate for information recording media with a 2W1 structure in which a cured resin with a concavo-convex pattern is adhered to the surface of a glass substrate. However, according to this embodiment, the thickness of the photosensitive resin film can be increased to form a photosensitive resin film with a thickness corresponding to the depth of the desired guide groove. It is possible to obtain a substrate for an information recording medium which can be made thinner and which prevents deterioration in performance such as durability and adhesiveness due to absorption and release of gas. Further, since the photosensitive resin pattern 3a contains a silicon compound, it is thermally stable. Therefore, the information recording medium substrate of this embodiment having the guide groove 6 formed by the pattern 3a has a good quality. Has heat resistance.

(Example 2) Triethoxyaluminum (A!L(OC2H5)3), which is a metal alkoxide, is used instead of tetraethoxysilane, which is a silicon alkoxide used in Example 1, and this triethoxyaluminum, water, and ethyl For information recording and media with guide grooves was prepared in the same manner as in Example 1, except that Cellsolve acetate was mixed in a ratio (molar ratio) of 1:2:5 to prepare a solution containing a hydrolyzate of aluminum alkoxide. I got the board. Note that the solution containing the hydrolyzate of aluminum alkoxide described above contains, in addition to the hydrolyzate, a partial hydrolyzate of aluminum alkoxide, a polymer of an aluminum compound, a trace amount of aluminum oxide, etc. .

Similar to the information recording medium substrate obtained in Example 1, the information recording medium substrate obtained in this example had an extremely smooth bottom surface of the guide groove, and had rough adhesion with the magneto-optical recording film. It also had excellent durability and heat resistance.

Although the present invention has been described in detail above, the present invention is not limited to the above embodiments, but includes the following applications and modifications.

(1) As the transparent substrate, a soda lime glass substrate was used in the embodiment, but other than soda lime glass, a glass substrate such as aluminoborosilicate glass, borosilicate glass, quartz glass, etc. may be used. In addition, in the example,
Although a glass substrate subjected to chemical strengthening treatment and then silazane treatment was used, the chemical strengthening treatment and the silazane treatment are not essential, and one or both of them may be omitted depending on the case.

As the light-transmitting substrate, a plastic substrate may be used instead of a glass substrate, and representative examples include substrates made of polycarbonate, polymethyl methacrylate, epoxy resin, and the like. Moreover, sapphire can also be used as a substrate. Further, as the substrate, in addition to the above-mentioned substrate having translucency, a substrate without translucency may be used, and examples thereof include substrates made of precision-polished aluminum, titanium, ceramic, or the like.

(2) In Example 1, a solution containing a silicon alkoxide hydrolyzate was prepared by mixing tetraethoxysilane, water, and ethyl cellosolve acetate.

Silicon alkoxides used when preparing a solution containing a hydrolyzate of silicon alkoxide include tetraethoxysilane, tetramethoxysilane, tetra-n-propoxysilane, tetra-1-propoxysilane, and tetra-n- butoxysilane, tetra-5ec
Tetraalkoxysilanes such as -butoxysilane and tetra-tert-butoxysilane, monoalkyltrialkoxysilanes, dialkyldialkoxysilanes, and trialkyl silanes in which 1 to 3 of the alkoxy groups of these tetraalkoxysilanes are substituted with alkyl groups. Examples include silicon alkoxides such as noalkoxysilane and their partial hydrolysates.

In addition, in Example 2, in order to prepare a solution containing a hydrolyzate of metal alkoxide, triethoxyaluminum, water, and ethyl cellosolve acetate were mixed to prepare a solution containing a hydrolyzate of aluminum alkoxide. In addition to triethoxyaluminum, trimethoxyaluminum, tri-n-butoxyaluminum, tri-propoxyaluminum, tri-n-butoxyaluminum, etc. can be used as the metal alkoxide used when preparing a solution containing a hydrolyzate of this metal alkoxide. trialkoxyaluminum, and 1 to 2 of the alkoxy groups of these trialkoxyaluminums.
Aluminum alkoxides such as monoalkyldiflukoxyaluminum and dialkylmonoalkoxyaluminum in which each is substituted with an alkyl group, and partial hydrolysates thereof can be mentioned. Further, as the metal alkoxide, alkoxides of tantalum, tungsten, tin, zirconium, titanium, etc., and partial hydrolysates thereof can also be used. It goes without saying that two or more of these metal alkoxides containing the same or different metals may be used as a mixture, and silicon alkoxides and metal alkoxides may be used as a mixture to form a hydrolyzate of silicon alkoxide. A solution containing a metal alkoxide and a metal alkoxide hydrolyzate may be prepared.

A mixed solution containing a hydrolyzate of silicon alkoxide or metal alkoxide and a photosensitive resin liquid was applied onto a substrate to form a photosensitive resin film, and the same method as in the example was applied. The photosensitive resin pattern formed on the substrate through the subsequent steps is thermally stable because it contains a silicon compound or a metal compound such as an aluminum compound, a tantalum compound, or a titanium compound.

In addition, in the example, a solution containing a hydrolyzate of silicon alkoxide or aluminum alkoxide was prepared by mixing tetraethoxysilane or triethoxyaluminum and water-ethyl cellosolve acetate in a ratio (mole ratio) of 1:2:5. However, the mixing ratio is determined as appropriate. Furthermore, as a solvent for the solution containing the hydrolyzate of silicon alkoxide or aluminum alkoxide, ethyl cellosolve acetate was used in the examples, but in addition to ethyl cellosolve acetate, methyl cellosolve acetate or methyl alcohol, ethyl alcohol, n-propyl alcohol, n
-butyl alcohol, 5ec-butyl alcohol, te
C1-8 aliphatic alcohols such as rt-butyl alcohol, polyhydric alcohols such as ethylene glycol, ethylene glycol monoethyl ether, acetic acid ethylene glycol monoethyl ether, and derivatives thereof may be used. Roughly speaking, water for hydrolysis is omitted from W4 polar mixing, and moisture (steam) in the air is taken into a mixture of silicon alkoxide or metal alkoxide and the above-mentioned solvent, and it is converted into silicon. A solution containing a hydrolyzate of an alkoxide or a metal alkoxide may also be used. Furthermore, a surfactant may be mixed into a solution containing a hydrolyzate of silicon alkoxide or metal alkoxide.

Next, as the photosensitive resin liquid, other positive resists other than the novolak positive photoresist used in the examples and other negative resists such as negative photoresists made of polyvinyl cinnamate resin were used. May be used.

Furthermore, the mixing ratio of the solution containing the silicon alkoxide or metal alkoxide hydrolyzate and the photosensitive resin liquid is as follows:
Decide accordingly.

In addition, as a method for applying a mixed solution obtained by mixing a solution containing a hydrolyzate of silicon alkoxide or a metal alkoxide and a photosensitive resin solution, other than the spin code method used in the examples, which allows easy control of the film thickness. Other methods such as spray coating may also be used.

Further, the thickness of the photosensitive resin film is determined depending on the desired depth of the guide groove, but it is usually 300 to 1500 people.

(3) In order to form a latent image corresponding to the guide groove on the photosensitive resin film, ultraviolet contact exposure was used in the example, but
A typical ultraviolet exposure method such as a close-up exposure method or a projection exposure method may also be used. Alternatively, a laser cutting method may be used.

In addition, the latent image formed on the photosensitive resin film is a continuous guide)
The latent image is not limited to one corresponding to M, but may be a circular or elliptical bit finally obtained on the information recording medium substrate, or a latent image corresponding to a continuous groove.

The pattern of the photomask used to form a latent image on the photosensitive resin film is different when the photosensitive resin film is made using a positive photoresist and when it is made using a negative photoresist. The difference is that when a positive pattern is used when fabricating using the former positive photoresist, it is necessary to use a negative pattern when fabricating using the latter negative photoresist.

(4) In order to form a photosensitive resin pattern by developing the photosensitive resin film on which the latent image has been formed, a wet developing process using a developer was adopted in the example. A developer may also be used. That is, an appropriate developer can be selected depending on the type and properties of the photosensitive resin film. Furthermore, instead of the wet development process, a dry development process may be used.

(5) In the example, a substrate for an information recording medium was obtained in which the transparent substrate was exposed after development and the surface of the transparent substrate formed the bottom surface of the guide groove, but it is necessary to adjust the ultraviolet exposure machine and the developer. Accordingly, a relatively shallow guide groove may be formed, and in this case, the photosensitive resin deposited on the transparent substrate forms the bottom surface of the guide groove.

In this case as well, since the development speed of the photosensitive resin film can be made uniform in the film thickness direction, the bottom surface of the guide groove can be made smooth.

(6) In the examples, the organic solvent (
For example, methylcellosolve acetate) and various gases (for example, f-120, N2, 02).

Although heat treatment was performed at 150° C. for 30 minutes to promote evaporation, release, and removal of CxHy), etc., this heat treatment is not essential and can be omitted in some cases.

When heat treatment is performed, the temperature is preferably 100°C or higher; however, if it exceeds 200°C, the photosensitive resin pattern will be significantly decomposed by heat, which is not preferred.

However, the in-groove recording method can be used even if the temperature is raised to 200° C. or higher.

(Effects of the Invention) As described in detail above, according to the present invention, for example, in the case of an information recording medium substrate with a guide groove, the bottom surface of the guide groove can be made smooth and has excellent properties such as heat resistance and durability. A substrate for an information recording medium can be obtained with good productivity and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing steps in the method for manufacturing a substrate for an information recording medium according to the present invention. DESCRIPTION OF SYMBOLS 1... Through hole, 2... Transparent substrate, 3... Photosensitive resin film, 3a... Photosensitive resin pattern, 3L... Latent image, 4... Photomask, 5... ...Ultraviolet light, 6...
Guide groove, 6a... bottom surface of the guide groove.

Claims (2)

[Claims] (1) A photosensitive resin film is formed by applying a mixture of a photosensitive resin liquid and a solution containing at least one of a silicon alkoxide hydrolyzate and a metal alkoxide hydrolyzate onto a substrate. The photosensitive resin film is then selectively exposed to light to form a latent image on the photosensitive resin film, and the photosensitive resin film on which the latent image has been formed is then developed to form a photosensitive resin. A method of manufacturing a substrate for an information recording medium, comprising forming a pattern on the substrate. (2) A substrate for an information recording medium, characterized in that a photosensitive resin pattern obtained by the method according to claim 1 is formed on the substrate.