JPH0242653A - Substrate for information recording medium and its production - Google Patents

Abstract

PURPOSE:To smooth the base of guide grooves and to uniformize the depth of the plural guide grooves by forming patterns consisting of a resin on one main surface of a transparent substrate and forming thin films contg. at least either of a silicon oxide and metal oxide so as to cover the patterns. CONSTITUTION:A photosensitive resin film 3 is formed on one main surface of the light transparent substrate 2 having a through-hole 1 in the central part, then this photosensitive resin film 3 is selectively exposed to form latent images 3l on the film 3. The film 3 formed with the latent images 3l is subjected to a development processing to form the patterns 3p consisting of the resin. Further, the thin films 6 contg. at least either of the silicon oxide and the metal oxide are so formed as to convert the patterns 3p in accordance with the shapes of the patterns 3p. The thin films 6 have projecting thin film pattern parts 6b corresponding to the resist patterns 3p and the guide grooves 7 are formed between the thin film pattern parts 6p and 6p. The base of the guide grooves is smoothed in this way and the depth of the plural guide grooves is uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a substrate for information recording media and a method for manufacturing the same, and specifically relates to an erasable and writable substrate, so-called E-DRAW.
The present invention relates to a substrate for an information recording medium suitable for use as a substrate for a type magneto-optical recording medium, or a write-once type or replaceable type optical information recording medium, and a method for manufacturing the same.

[Prior Art] In recent years, in the above-mentioned substrates for information recording media,
It has been proposed to provide a guide groove for tracking laser light used for recording and reproducing information (for example, see Japanese Unexamined Patent Publication No. 160847/1983).

Conventionally, information recording medium substrates manufactured through the steps described below are known.

That is, first, after grinding into a disc shape, high-precision he
A photoresist is applied onto one main surface of the soda lime glass substrate. Next, the photoresist is selectively exposed to laser light and developed to form a resist pattern. Next, using the resist pattern as a mask, the soda lime glass substrate is etched by a dry etching method using carbon tetrafluoride (CFa) gas to a predetermined depth required as the depth of the guide groove. Next, by peeling off the resist pattern, an information recording medium substrate having guide grooves formed on the entire surface of the soda lime glass substrate is obtained (see, for example, Japanese Patent Laid-Open No. 59-210547).

An information recording medium manufactured using the above-described information recording medium substrate includes an information recording layer made of, for example, GdTbFe, which is adhered to the entire surface of a soda lime glass substrate on which guide grooves are formed. .

[Problems to be Solved by the Invention] However, the information recording medium substrate manufactured through the process of forming guide grooves on the lifetime surface of the soda lime glass substrate as described above has the following two problems. A point occurs.

That is, when etching a soda lime glass substrate as described above, it is difficult to equalize the etching rate for the portion to be etched, so the surface roughness of the bottom surface of the guide groove increases and the surface is not smooth. For this reason, in an information recording medium manufactured using this information recording medium substrate, the laser beam is scattered by the information distribution layer deposited on the bottom surface, and the S/N ratio (information signal and noise) during information reproduction is (strength ratio) decreases.

Furthermore, since it is difficult to equalize the etching speed as described above, the depths of the plurality of guide grooves formed differ from each other. As a result, in the information recording medium manufactured using this information recording medium substrate, stable tracking cannot be performed and information cannot be reproduced satisfactorily.

The present invention has been made in view of the above circumstances. For example, in the case of an information recording medium substrate with a guide groove, the bottom surface of the guide groove is smooth and the depth of the plurality of guide grooves formed is uniform. An object of the present invention is to provide a substrate for an information recording medium.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and the information recording medium substrate of the present invention includes a light-transmitting substrate and a main component of the light-transmitting substrate. a pattern made of resin formed on a surface; a thin film containing at least one of silicon oxide and metal oxide formed to cover the pattern in accordance with the shape of the pattern; It is characterized by having the following.

Further, the method for manufacturing a substrate for an information recording medium of the present invention includes forming a photosensitive resin film on one main surface of a light-transmitting substrate, and then selectively exposing the photosensitive resin film to A latent image is formed on the film, and the photosensitive resin film on which the latent image has been formed is developed to form a pattern made of resin, and further contains at least one of silicon oxide and gold jl oxide. The method is characterized in that a thin film formed by the method is formed so as to correspond to the shape of the pattern and cover the pattern.

[Examples] Example 1 First, an example of a method for manufacturing an information recording medium substrate of the present invention will be described with reference to FIG.

Made of soda lime glass, outer diameter 130sφ, inner diameter 1
After precision polishing the surface of a glass disk with a diameter of 5 aw and a thickness of 1.2 am, it was chemically strengthened by immersing it in molten potassium nitrate salt set at a temperature of 400°C for 8 hours, and then being exposed to air. A silazane treatment was performed by exposing the substrate to hexamethyldisilazane vapor to obtain a transparent substrate 2 having a through hole 1 in the center.

A novolak-based positive photoresist (T made by Tokyo Ohka Kogyo Co., Ltd.) is applied as a photosensitive resin to the upper surface of the light-transmitting substrate 2.
A positive photoresist film 3 was formed by applying SMR8900) to a film thickness of 700 nm using a spin code method (see FIG. 1 (2)).

Next, this photoresist film 3 is selectively exposed to light using a UV density II exposure method using a photomask 4 having a pattern corresponding to the guide groove of the finally obtained information recording medium substrate and ultraviolet rays 5. , latent image 3 corresponding to the guide groove
1 (see Figure 1).

Next, the exposed photoresist film 3 was developed using an alkaline developer (NMD-W manufactured by Tokyo Ohka Kogyo Co., Ltd.), washed with water, and dried to obtain a resist pattern 3p as a resin pattern ( (See Figure 1 (b)).

Then, tetraethoxysilane (S i (OC2)-
15) 4), water, methyl alcohol, and acetic acid at 1=2:1
A solution containing a hydrolyzate of tetraethoxysilane is obtained by mixing at a ratio (molar ratio) of 0:0.2, and this solution is applied onto a transparent substrate 2 having a resist pattern 3p by a spin code method. After being coated on the surface, heat treatment is performed in the air at a temperature of 150°C for 30 minutes to form a silicon oxide-containing product.
A W4 film 6 having a film thickness of 100% was formed (see FIG. 1).

This thin film 6 has a convex shape i corresponding to the resist pattern 3p.
1 film pattern part 6p, and this convex thin film pattern part 6
A guide groove 7 is formed at p and 6pfill.

In the information recording medium substrate thus obtained, the bottom surface 7a of the guide groove 7 contains silicon oxide obtained by the sol-gel method, so the surface roughness is small.
It was very smooth. Therefore, in an information recording medium manufactured using this substrate for information recording media, scattering of laser light in the information recording layer deposited on the bottom surface 7a is suppressed, and it is possible to improve the S/N ratio when reproducing information. becomes.

In addition, a photoresist film 3 having a uniform thickness is developed up to the -1 surface of the transparent substrate 2 to form a resist pattern 3.
D. After forming concave portions of uniform depth between the three layers, the sol
Since the guide grooves 7 are formed by depositing a uniform thin film 6 containing silicon oxide by a gel method, each guide groove 7 has a uniform depth. Therefore, in an information recording medium manufactured using an information recording medium substrate provided with such a guide groove, stable tracking can be performed and information can be reproduced satisfactorily.

Next, on the information recording medium substrate with guide grooves obtained in this example, silicon was used as a target, a mixed gas of Ar and N2 (Ar/N2-2/1) was used as a reactive gas, and a pressure of 10 mTorr was applied. First, a transparent base layer consisting of a silicon nitride film with a thickness of 800 μm is formed by a reactive sputtering method using 1 μm as high frequency power, and on top of that, TbFeCo as a target, Ar as a gas, and 10 m Tarr1 high frequency as a pressure. A TbF film with a thickness of 1000 nm was produced by sputtering using a power of 0.5 to -.
Next, a magnetic layer consisting of an eCo film is formed, and silicon is used as a target and Ar is used as a reactive gas on top of the magnetic layer.
A protective film layer consisting of a silicon nitride film with a thickness of 2,000 yen was formed by a reactive sputtering method using a mixed gas of N and N (Ar/N2-2/1), a pressure of 10 TrL orr, and a high frequency power of 1 to 1. An information recording medium having an information recording layer composed of these three layers was obtained.

Scotch tape (trade name of tape manufactured by 3M Company, USA) was pasted on the obtained information recording medium to examine the adhesion between the information recording medium substrate with guide grooves and the information recording layer provided thereon. After peeling off the film, a beer test was performed, but no peeling of the film occurred. Furthermore, the information recording medium was subjected to a beat cycle test (number of cycles: i ooo) under the conditions of 25°C on the low temperature side, 150°C on the high temperature side, holding time for 1 hour each, atmospheric stomach temperature, and temperature decreasing rate of 50°C/min.

After conducting the above-mentioned beer test, it was found that the film did not peel off and was stable and heat resistant.

Furthermore, the information recording medium substrate obtained in this example and having the thin film 6 as the outermost layer is ill! It was also found that the substrate has superior adhesion to the information recording layer and heat resistance compared to an information recording medium substrate having the same structure except that it does not have the following. The reason why excellent adhesion is obtained in the information recording medium substrate of this example is that the adhesion between the information recording layer and the substrate 2 with the resist pattern 3p when the WI film 6 is not present is quite satisfactory. However, in the case of the information recording medium substrate having 11I6 obtained in this example, this [16 is the substrate 2 with resist pattern 3p.
It has a strong affinity for both the information storage layer and the information recording layer.
This is because by firmly linking the two, the adhesion is further improved. The reason why the information recording medium substrate of this example has excellent heat resistance is that the thin 111
This is because the resist pattern 3p acts as a protective layer for the resist pattern 3p, and can eliminate the adverse effects of heat on the resist pattern 3p during heating or the like. Therefore, since the shape of the resist pattern 3p is not easily changed by heating, the shape of the guide groove 7 formed between the resist patterns 3p does not change either.

In addition, the thin film 6 can be formed by cleaning the information recording medium substrate with an organic solvent, which is usually carried out in advance, when a transparent underlayer and a magnetic layer are deposited sequentially or when a magnetic layer is deposited directly. Since the resist pattern 3p is prevented from being exposed to organic solvents, deformation of the resist pattern 3p due to swelling etc. is suppressed and durability is improved.

Example 2 Tetraethoxysilane (S
i (OC2Hs )a ), metal alkoxide triethoxyaluminum (AI(OC2H5 )
)a>, this triethoxyaluminum, water, methyl alcohol, and acetic acid are mixed in a ratio (molar ratio) of 1:2:10:0.2 to contain a hydrolyzate of triethoxyaluminum. Example 1 except that the solution was prepared
In the same manner as above, an information recording medium substrate with guide grooves is assembled.

Similar to the information recording medium substrate obtained in Example 1, the information recording medium substrate obtained in this example had a small surface roughness on the bottom surface of the guide groove and was very smooth. The grooves had a uniform depth, and were also excellent in adhesion to the information recording layer, heat resistance, durability, etc.

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 examples, a glass substrate was used that was subjected to chemical strengthening treatment and then silazane treatment, but chemical strengthening treatment and silazane treatment were
It is 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.

(2) As the material for the photosensitive resin film formed on the light-transmitting substrate, other positive photoresists other than the novolak positive photoresist used in the examples, polyvinyl cinnamate resin, etc. A negative type photoresist may be used, and furthermore, a positive type electron beam resist such as a polyolefin sulfone type or a negative type electron beam resist such as a styrene type may also be used.

Further, the thickness of the resist 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 resist film, an ultraviolet contact exposure method was adopted in the actual example, but other ultraviolet exposure methods such as a close exposure method or a projection exposure method may be used. Alternatively, a laser cutting method may be used. Further, when using an electron beam resist, an exposure machine such as an electron beam exposure device is used.

In addition, the latent image formed on the resist film is not limited to continuous guide grooves, but may also be a latent image corresponding to circular or elliptical pits that are finally obtained on the information recording medium substrate, or a series of intermittent grooves. There may be.

(4) In order to form a resist pattern by developing the resist film on which the latent image has been formed, a wet development process using an alkaline developer was adopted in the example, but it is possible to use another developer during wet development. Also good. An appropriate developer can be selected depending on the type and properties of the resist film.

Furthermore, instead of the wet development process, a dry development process may be used.

(5) As a solution for forming a thin film containing silicon oxide by the sol-gel method, in Example 1, tetraethoxysilane, water, methyl alcohol, and acetic acid were mixed to form a hydrolyzate of silicon alkoxide. In addition to tetraethoxysilane, the silicon alkoxide used to prepare the solution containing the silicon alkoxide hydrolyzate includes tetramethoxysilane, tetra-n-propoxysilane, and tetra-1.
- Tetraalkoxysilanes such as propoxysilane, tetra-n-butoxysilane, tetra-5ec-butoxysilane, and tetra-tert-butoxysilane, and 1 to 3 of the alkoxy groups of these tetraalkoxysilanes are substituted with alkyl groups. Examples include silicon alkoxides such as monoalkyltrialkoxysilanes, dialkyldialkoxysilanes, and trialkylmonoalkoxysilanes, and partial hydrolysates thereof.

Further, in Example 2, triethoxyaluminum, water, methyl alcohol, and acetic acid were mixed to contain a hydrolyzate of aluminum alkoxide as a solution for forming a thin film containing a metal oxide by a sol-gel method. The metal alkoxide used to prepare the solution containing the metal alkoxide hydrolyzate includes triethoxyaluminum, trimethoxyaluminum, tri-low propoxyaluminum, treaty-propoxyaluminum, and tri-low. trialkoxyaluminum such as butoxyaluminum,
Aluminum alkoxides such as monoalkyldialkoxyaluminum and dialkylmonoalkoxyaluminum in which one or two of the alkoxy groups of these trialkoxyaluminums are substituted with alkyl groups, and their partial hydrolysates are 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.

Note that a solution containing a hydrolyzate of silicon alkoxide or metal alkoxide is applied onto a transparent substrate with a resist pattern, and then formed on the transparent substrate with a resist pattern through the same subsequent steps as in the example. The resulting thin film is thermally stable because it contains silicon oxide or metal oxides such as aluminum oxide, tantalum oxide, and titanium oxide.

In addition, in the examples, tetraethoxysilane or triethoxyaluminum, water, methyl alcohol, and acetic acid were mixed in 1:
A solution containing a hydrolyzate of silicon alkoxide or aluminum alkoxide was prepared by mixing at a ratio (molar ratio) of 2:10:0.2, but the mixing ratio can be determined as appropriate. Also, mixing acetic acid may be omitted. Furthermore, in the examples, methyl alcohol was used as the solvent for the solution containing the hydrolyzate of silicon alkoxide or metal alkoxide, but in addition to methyl alcohol, ethyl alcohol, n-propyl alcohol, n-butyl alcohol , C1-8 aliphatic alcohols such as 5eC-butyl alcohol, tert-butyl alcohol, polyhydric alcohols such as ethylene glycol, ethylene glycol monobutyl ether, acetic acid ethylene glycol monoethyl ether, and derivatives thereof may be used. . Also, methyl cellosolve acetate or ethyl cellosolve acetate may be used.

Furthermore, without actively mixing water for hydrolysis, 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 alkoxide or metal alkoxide. A solution containing a metal alkoxide hydrolyzate may also be used. Furthermore, a surfactant may be mixed into a solution containing a hydrolyzate of silicon alkoxide or metal alkoxide.

In addition, as a method for applying the solution containing the hydrolyzate of silicon alkoxide or metal alkoxide, in addition to the spin-coating method used in the examples, which allows easy control of the film thickness, other methods such as spray coating were used. Good too.

As the heat treatment temperature for converting the hydrolyzate of silicon alkoxide into silicon oxide, 150°C was adopted in Example 1, but the temperature is not limited to this, and 100°C
Any above is sufficient.

However, if the temperature exceeds 200°C, the resin pattern will decompose significantly due to heat, which is undesirable, but in the groove recording method,
It can be used even if the shoulder part is heated to 200°C or higher. Further, the heat treatment temperature of the metal alkoxide is appropriately determined depending on the type of metal. The thickness of the thin film containing silicon oxide or metal oxide formed by the sol-gel method is not limited to 100 in the example, and can be selected as appropriate. Moreover, this thin film may consist of multiple layers.

(6) The thin film containing silicon oxide or metal oxide may be formed using a method other than the Soluglu method as long as the film thickness can be easily controlled, such as sputtering method or vacuum evaporation method. , plasma CVD method, etc. are used.

(7) In the example, after the transparent substrate is exposed after development, a thin film made of silicon oxide or aluminum oxide is applied, so that the surface of one film on the transparent substrate forms the guide groove. Although the information recording medium substrate forming the bottom surface was obtained, ultraviolet I! i! By adjusting the exposure amount and development amount, relatively shallow guide grooves may be formed without exposing the light-transmitting substrate. In this case, silicon oxide deposited on the resist film may be formed. The material or metal oxide forms the bottom surface of the guide groove.

[Effects of the Invention] As described above in detail, 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 is smooth and the depth of the plurality of guide grooves formed is A substrate for an information recording medium that is uniform and has excellent adhesion to the information recording layer, heat resistance, etc. is used.

[Brief explanation of the drawing]

FIG. 1 is a process diagram for manufacturing the information recording medium substrate of the present invention. DESCRIPTION OF SYMBOLS 1... Through hole, 2... Transparent substrate, 3... Photoresist film, 3ρ... Resist pattern, 31...
Latent image, 4... Photomask, 5... Ultraviolet light, 6...
・Thin film, 6p... Convex thin film pattern part, 7... Guide groove, 7a... Bottom surface of guide groove

Claims (2)

[Claims] (1) A transparent substrate, a pattern made of resin formed on one main surface of the transparent substrate, and a silicon oxide formed to cover the pattern in accordance with the shape of the pattern. and a thin film containing at least one of metal oxides. (2) Form a photosensitive resin film on one main surface of a light-transmitting substrate, then selectively expose the photosensitive resin film to form a latent image on the photosensitive resin film, and then The photosensitive resin film on which the latent image has been formed is developed to form a pattern made of resin, and a thin film containing at least one of silicon oxide and metal oxide is formed in a shape corresponding to the shape of the pattern. A method of manufacturing a substrate for an information recording medium, characterized in that the substrate is formed so as to cover the pattern.