JP2001325722A - Method for manufacturing substrate for information recording medium and method for manufacturing information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a crystallized glass substrate for an information recording medium, excellent in sliding reliability and having surface properties capable of high recording density and high rigidity and to provide a method for manufacturing the information recording medium using the substrate. SOLUTION: In the method for manufacturing glass substrate for the information recording medium, consisting of a crystallized glass in which crystal particles are dispersed in a continuous phase of amorphous glass, the crystallized glass substrate whose principal surface is polished is subjected to surface treatment using an aqueous solution containing fluorosilicic acid to control the surface roughness of a projecting and recessing part contributing to sliding characteristics with a recording and reproducing head and formed on the principal surface of the substrate. The method for manufacturing the information recording medium is also provided, in which at least an information recording layer is formed on the principal surface of the glass substrate for the information recording medium obtained by the method above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a glass substrate for an information recording medium having high rigidity and high smoothness, and a method for manufacturing an information recording medium using the substrate. In particular, a magnetic disk using a crystallized glass substrate obtained by the manufacturing method of the present invention is less likely to cause adhesion to a magnetic head, has excellent sliding reliability and head flying characteristics, and further has the characteristics of the present invention. The substrate is a substrate suitable for manufacturing a low-cost magnetic disk.

[0002]

2. Description of the Related Art Conventionally, the surface of a substrate for a thin film magnetic disk has been
A demand for prevention of adhesion to the head and the like has necessitated an appropriate roughness rather than a mirror surface. Examples of methods for imparting appropriate roughness to the substrate surface include various methods such as a method of machining concentric grooves called texture on the NiP surface of Al / NiP and a method of dispersing fine particles in a base plating film. A method has been devised.

[0003]

For example, in a magnetic disk in which an underlayer Cr film, a magnetic film medium, a protective film, and a lubricating oil film are formed on a polished boundary surface of an Al / NiP substrate, when the head is stopped, the disk and the head are stopped. The lubricating oil and moisture collect on the contact surface of the head, causing a head sticking phenomenon. For this reason, the rotation of the disk becomes impossible and the components of the head holding mechanism are broken or deformed, which is a problem. Therefore, a method of roughening the surface of the disk by texturing to form concentric grooves on the polished surface of Al / NiP to prevent sticking is now widely used. However, such texture processing uses NiP with fine abrasive grains.
Since the polishing is performed by grinding the surface, burrs due to the plastic flow of the material at the time of processing and re-attachment of chips tend to easily cause projections colliding with the head.

[0004] There is no substrate which has been subjected to such texture processing which satisfies all the points of disk performance, cost and mass productivity, and in fact, it must be used without any of the characteristics being satisfied. It was a situation. Further, it is difficult to form a surface for floating the head with a spacing of 30 nm or less over the entire surface of the disk by the above-described texture processing. The recording density of magnetic disks is increasing at an accelerating rate year by year. In order to further increase the recording density of magnetic disks, it is necessary to further reduce the flying distance of the magnetic head from the current state. Such texture processing cannot be used at all.

A glass substrate is known as a substrate other than the Al / NiP substrate. In particular, it is known that a chemically strengthened glass substrate is used as a magnetic disk substrate. A chemically strengthened glass substrate is obtained by subjecting lithium or sodium ions in the surface layer of ordinary glass to ion exchange treatment with potassium ions with a larger ionic radius, etc., and providing a strengthening layer having compressive stress on the surface of the glass. , A glass substrate hardly broken. When actually forming a magnetic disk using this tempered glass substrate,
It is necessary to use the same texture processing as the NiP plating film to appropriately roughen the surface. However, when the glass surface having a compressive stress is textured, it is easy to cause the peripheral portion to be applied, and it is difficult to form a textured surface having a uniform surface shape and no defect.

[0006] Japanese Patent No. 3012660 (hereinafter referred to as prior art 1)
Discloses a method of manufacturing a low-cost magnetic disk substrate using crystallized glass with excellent sliding reliability. This prior art 1 is formed by a crystal nucleus generation heat treatment step for generating crystal nuclei in glass and a crystal nucleus growth heat treatment step for growing crystal nuclei to a predetermined size. After the glass surface is mirror-polished, it is immersed in a hydrofluoric acid aqueous solution containing at least hydrogen fluoride, leaving the crystal phase on the glass substrate surface and selectively etching the amorphous phase to a predetermined depth. And
It is disclosed that irregularities are formed on the surface of a glass substrate. However, the minimum flying height of the magnetic head possible using the crystallized glass substrate obtained by this manufacturing method is 0.08 μm
In the near future, it is difficult to obtain a crystallized glass substrate that realizes a flying height of the magnetic head of 30 nm or less, which can cope with a high recording density required for a recording medium. The following points can be considered as the cause. When viewed as a glass substrate, achieving low flying of the magnetic head cannot be achieved merely by improving the smoothness of the substrate surface, and the medium does not deform when the medium is rotated, that is, it supports the information recording layer etc. It is also required that the substrate is not deformed. Further, as the recording density increases, the rotation speed of the recording medium is further increased. During high-speed rotation, if the rigidity of the substrate is low, the medium bends and hinders a reduction in the flying height of the magnetic head. However, although Prior Art 1 mentions the bending strength of the substrate, it does not consider the problem of rigidity that causes deflection during high-speed rotation. Next, when looking at a method for manufacturing a glass substrate, an etching rate for selectively etching an amorphous phase in a crystallized glass substrate is high because an aqueous hydrofluoric acid solution containing hydrogen fluoride is used. In order to obtain high sliding reliability, it is necessary to precisely control the desired substrate surface roughness. However, the high etching rate makes it difficult to control the roughness, and the etching rate varies significantly. Therefore, there is a problem that the sliding reliability when the flying height is lowered is poor. In addition, when etching is performed after the polishing process, the polishing abrasive grains cannot be sufficiently cleaned after the etching processing, and the polishing abrasive grains remain. As a result, there is a problem in that the low flying height of the head is hindered.

In view of the above problems, the present invention provides a method for manufacturing a crystallized glass substrate for an information recording medium which has excellent sliding reliability, has a surface property enabling high recording density, and has high rigidity. It is another object of the present invention to provide a method for manufacturing an information recording medium using the substrate.

[0008]

The present invention for solving the above problems is as follows. (1) A method for producing a glass substrate for an information recording medium, comprising a crystallized glass in which crystal particles are dispersed in a continuous phase of an amorphous glass, wherein a crystallized glass substrate having a main surface polished is coated with a silicon oxide. A glass substrate for an information recording medium, which is subjected to a surface treatment using an aqueous solution containing an acid to control the surface roughness of irregularities formed on a main surface of the substrate, which contributes to sliding characteristics with a recording / reproducing head. Manufacturing method. (2) The glass for an information recording medium according to (1), wherein the surface treatment partially causes crystal grains contained in the crystallized glass substrate to partially protrude from a continuous phase on the main surface. Substrate manufacturing method. (3) The crystallized glass substrate melts a glass raw material,
The obtained molten glass is formed into a glass substrate, and a crystal nucleus generation heat treatment step for generating crystal nuclei of the obtained glass substrate and a crystal nucleus growth heat treatment step for growing the crystal nuclei to predetermined dimensions are performed. The method for producing a glass substrate for an information recording medium according to (1) or (2), which is obtained by applying the method. (4) The surface treatment is performed on the glass substrate for an information recording medium according to any one of (1) to (3), wherein the surface roughness (maximum height) Rmax of the main surface of the substrate is 1 to 30 nm. Production method. (5) The aqueous solution containing silicic acid is 0.01 to 1.0% by weight.
The method for producing a glass substrate for an information recording medium according to any one of (1) to (4), comprising: (6) The method for producing a glass substrate for an information recording medium according to any one of (1) to (5), wherein the aqueous solution containing silicic acid contains silicic acid and hydrofluoric acid. (7) The ratio of hydrofluoric acid to hydrofluoric acid (weight% ratio) is 1: 1
(10). The method for producing a glass substrate for an information recording medium according to (6), wherein (8) The crystal nucleation heat treatment step is performed under the condition that the areal density of crystal nuclei to be crystal grains existing on the main surface of the substrate is more than 10 ⁶ / mm ² and not more than 10 ⁹ / mm ² , And the crystal nucleus growth heat treatment step is carried out under conditions for growing the crystal nuclei into crystal grains having a grain size of 1000 nm or less, for the information recording medium according to any one of (1) to (7). A method for manufacturing a glass substrate. (9) The main surface of the polished crystallized glass substrate has a surface roughness Ra of 2 nm or less.
(8) The method for producing a glass substrate for an information recording medium according to any one of (8). (10) The crystallized glass is at least SiO ₂ , A1
_The method for producing a glass substrate for an information recording medium according to any one of (1) to (9), comprising a crystallized glass containing ₂ O ₃ , MgO, and TiO ₂ . (11) said crystallized glass, a SiO ₂ 35 to 65 mol%, A1 ₂
O ₃ 5 to 25 mol%, MgO 10 to 40 mol%, the TiO ₂ 5 to 15 mol%
And the main crystal is enstatite and / or a solid solution thereof (1).
The method for producing a glass substrate for an information recording medium according to 0). (12) said crystallized glass, a SiO ₂ 42-65 mol%, A1 ₂
O ₃ and 11 to 25 mol%, including MgO 15-33 mol%, the TiO ₂ containing 5.5 to 13 mol%, a main crystal as α- quartz solid solution and enstatite and / or enstatite solid solution (10)
3. The method for producing a glass substrate for an information recording medium according to claim 1. (13) A method for manufacturing an information recording medium, comprising forming at least an information recording layer on a main surface of a glass substrate for an information recording medium obtained by the method according to any one of (1) to (12). .

[0009]

Embodiments of the present invention will be described below. The present invention is a method for producing a glass substrate for an information recording medium comprising crystallized glass in which crystal particles are dispersed in a continuous phase of amorphous glass. And the present invention
A crystallized glass substrate whose main surface is polished is subjected to a surface treatment using an aqueous solution containing silica hydrofluoric acid to form a main surface of the substrate that contributes to the sliding characteristics with a recording / reproducing head (write / read head). It is characterized in that the surface roughness of the irregularities to be formed is controlled. Here, the irregularities contributing to the sliding characteristics with the recording / reproducing head are those formed on the main surface of the substrate on which the information recording layer to be opposed to the recording / reproducing head surface is provided. That can prevent the head for use from adsorbing to the information recording medium and reduce the friction coefficient.

The crystallized glass substrate used in the manufacturing method of the present invention is not particularly limited as long as the crystallized glass substrate has a main surface polished. For example, a glass material is melted, the obtained molten glass is formed into a glass substrate, and the obtained glass substrate is subjected to a crystal nucleus generation heat treatment step for generating crystal nuclei, and the crystal nuclei are grown to predetermined dimensions. Of a crystallized glass substrate obtained by subjecting the crystallized glass substrate to a crystal nucleus growth heat treatment step for polishing.

The crystallized glass substrate having the main surface polished is, for example, prepared by mixing raw materials at a predetermined composition ratio and melting the raw materials at a predetermined temperature (for example, a temperature range of 1400 to 1600 ° C.). The melt of the glass thus obtained is formed into a glass plate by a molding method such as a pressing method or a float method. It can be obtained by precipitating crystal grains and then performing grinding and polishing. The particle size and density of the crystal particles can be controlled by the composition of the glass and the heat treatment conditions.

The heat treatment method comprising the crystal nucleation heat treatment step and the crystal nucleus growth heat treatment step is not particularly limited, and may be appropriately selected according to the content of the crystallization promoter, the glass transition temperature, the crystallization peak temperature, and the like. Can be. However, a relatively low temperature (for example, 700 to 85
0 ° C.) to generate a large number of crystal nuclei (specifically, preferably, the areal density of the crystal nuclei exceeds 10 ⁶ / mm ² and 10 ⁹ / mm ² or less). It is preferable to increase the temperature to 850 to 1150 ° C. in the nucleus growth heat treatment step to grow the crystal from the viewpoint of miniaturizing the crystal. The particle size of the crystal particles obtained by growing the crystal nucleus is 1000 nm or less (preferably 500 nm).
nm or less, more preferably 300 nm or less, particularly preferably 100 nm or less). In the production of crystallized glass, the size and amount of precipitated crystals can be controlled by sequentially changing the heat treatment schedule or the glass composition, thereby greatly adjusting the properties of the crystallized glass. In addition, the allowable temperature range of crystal nucleation heat treatment and crystal growth heat treatment for producing crystallized glass having the same Young's modulus, the same crystal grain size, or the same crystallization homogeneity has a temperature range of 30 ° C or more. In addition, the production process of crystallization can be easily controlled.

In particular, in a method for producing crystallized glass in which glass containing TiO ₂ is made into crystallized glass through a phase separation step and a crystallization step, the phase separation step converts the glass from the glass transition temperature Tg. The heating is preferably performed by heating at a temperature in the range of the transition temperature Tg of the glass + 60 ° C. By this manufacturing method, the particle size of the crystal particles of the main crystal phase
A crystallized glass suitable for an information recording disk substrate having a transmittance in the range of 10-100 nm and a wavelength of 600 nm of 40% or more is obtained.

[0014] TiO ₂ contained in the glass as a starting material in the method of the crystallized glass through a glass phase separation step and a crystallization step of containing the TiO _2, the crystal nucleation in the course of the preparation of the crystallized glass It is a component that becomes an agent. TiO ₂ content is Tg + heat treatment at temperature below 60 ° C (phase separation step)
In the above, from the viewpoint that the glass is sufficiently phase-separated and the crystal particles of the crystallized glass obtained in the crystallization step have a desired relatively small size, it is appropriate to set the content to 8 mol% or more. In order to precipitate smaller crystal grains from the glass, the content of TiO ₂ is preferably 8.5 mol% or more. The upper limit of the content of TiO ₂ is 15 mol%, and is 12 mol% or less from the viewpoint that the glass melted in the production process can obtain moldable stability.

The glass containing TiO ₂ as a starting material is
For example, containing TiO _2, and MgO, Al ₂ O ₃ and MgO-Al ₂ O ₃ -SiO ₂ based glass or MgO-RO-Al ₂ O ₃ total content of SiO ₂ is 80 mol% or more —SiO ₂ (R = at least one selected from the group consisting of alkaline earth metals (for example, Ca, Sr, Ba), Zn, and Ni) can be used. These TiO ₂ crystal nucleating agent MgO-Al ₂ O ₃ -SiO ₂ -based glass to and _{MgO- (RO) -Al 2 O 3} -SiO 2 based glass is likely very phase separation in the vicinity of Tg, the As in the invention, it is suitable for producing crystallized glass having a fine crystal structure using a differential phase at a lower temperature. Examples of the glass containing TiO ₂ as a starting material include the above-mentioned U.S. Pat.
The glass described in 491116 can be mentioned. Or SiO ₂ : 35-65 mol%, Al ₂ O ₃ : 5-25 mol%, MgO: 10-
40 mol%, SiO ₂ + Al ₂ O ₃ + MgO ≦ 80 mol%, TiO ₂ : 5-15 mol%, RO (R = alkaline earth metal (Ca, Sr, Ba), Zn and Ni
At least one selected from the group consisting of: 0-10 mol%
Can be cited. Further, this method can be applied to at least crystallized glass 1, 2, 4 to 7 described later.

The glass containing TiO ₂ as a starting material is
Alkaline metal oxides (eg, Li ₂ O, Na ₂ O, K ₂ O, etc.) and / or alkaline earth metal oxides (eg, CaO, SrO, BaO) )). When the glass containing TiO ₂ as the starting material is the above-mentioned MgO-Al ₂ O ₃ -SiO ₂ glass containing TiO ₂ , the glass further contains an alkali metal oxide and / or an alkaline earth metal oxide. be able to. Further, when the glass containing TiO ₂ as a starting material is the above-mentioned MgO-RO-Al ₂ O ₃ -SiO ₂ glass containing TiO ₂ , an alkali metal oxide can be further contained. As a matter of course, two or more kinds of alkali metal oxides and alkaline earth metal oxides can be used in combination.

Alkali metal oxide and / or alkaline earth
Metal oxides can use nitrate as a glass material.
You. Sb as a defoamer during glass production_TwoO_ThreeWhen you use
Platinum is easily mixed into the glass from the glass melting platinum crucible,
By using nitrate as a glass raw material,
Can be suppressed from being mixed in with platinum. Alkali metal
The contents of oxides and alkaline earth metal oxides are respectively
0.1% by mole or more from the viewpoint of obtaining the above effect
Are preferred. However, when alkali metal oxides are included,
Lucari metal oxides tend to reduce Young's modulus
Therefore, it is appropriate that the content is 5 mol% or less
You. When containing an alkaline earth metal oxide,
Earth metal oxides tend to make the crystal grains larger.
Therefore, it is appropriate that the content is 5 mol% or less.
You. When containing an alkali metal oxide, especially 0.1 to 5 mol
%, Preferably 0.1 to 2 mol%, more preferably 0.1 to 1 mol
% K _TwoO is preferred. Sites containing alkaline earth metal oxides
In particular, 0.1-5 mol%, preferably 0.1-2 mol% of SrO
Is preferred. The crystallized glass produced by the above method
As the crystal phase, for example, enstatite or a solid solution thereof
And / or a solid solution of quartz.

The respective heat treatment processes in the method for producing crystallized glass will be further described below. Containing TiO ₂ in a certain amount _{MgO- (RO) -Al 2 O 3} -SiO 2 (R
= Alkaline earth metals (eg, Ca, Sr, Ba), Zn or N
i) When the system glass is heat-treated at a temperature higher than the Tg temperature,
It is divided into two phases: a glass phase rich in iO ₂ and a phase rich in SiO ₂ . So-called glass becomes a phase separation (phase separation step). Such a phase separation of the glass has a great influence on the crystal seeds and crystal grain size of the crystallized glass. Usually, the TiO ₂ -rich phase is dispersed in the form of fine particles in the SiO ₂ -rich glass matrix phase. The smaller the size of the fine particles rich in TiO ₂ , the smaller the size of the final crystal particle having this differential phase particle as a nucleus. How to precipitate such differential phase particles small is the point of producing fine crystallized glass. In the above method, the surface roughness of the crystallized glass that has been heat-treated for phase separation in a temperature range from Tg temperature to Tg + 60 ° C. is 0.5 nm.
It is as follows. This is because the size of the crystal grains in the glass subjected to the phase separation in the temperature range from Tg temperature to Tg + 60 ° C. became smaller. From the viewpoint that crystallized glass with a small surface roughness can be obtained, the heat treatment for phase separation is
It is preferable that the temperature range is Tg + 10 ° C. or more, and Tg + 50 ° C. or less, Tg + 20 ° C. or more, Tg + 40 ° C.
More preferably, the temperature range is as follows. The Young's modulus and expansion coefficient of the crystallized glass prepared by this method are almost the same as those of the crystallized glass pre-treated by the conventional heat treatment method or the crystallized glass without the pre-treatment, and the mechanical properties and the crystallized glass Only the particle size of the crystal particles can be reduced without changing the thermal characteristics.

In this production method, it is preferable to raise the temperature of the glass obtained in the phase separation step to a heating temperature in the crystallization step at a rate of 10 ° C./min or less (600 ° C./hr or less). The reason why the rate of temperature rise from the processing temperature to the crystallization processing temperature in the phase separation step is suppressed to 10 ° C./min or less is to avoid deformation of the glass. Since normal crystallized glass is subjected to a heat treatment for phase separation at a higher temperature, the glass was already partially crystallized during the processing. Therefore, it was difficult to deform even if the heating rate was high. However, the glass heat-treated for phase separation by this method does not contain crystal particles, and if the temperature is raised quickly, the glass may be deformed. 10 ° C /
When the temperature is raised at a slow speed of not more than one minute, the crystal particles gradually precipitate during the temperature rise, so that deformation of the glass can be suppressed. The heating rate is preferably 1 to 7 ° C./min (60 to 4
20 ° C / hr). A lower heating rate is also very advantageous for the homogenization of the crystal grains. The heating for crystallization is
The size of the glass crystal particles, crystallinity, and appropriately determined in consideration of properties such as Young's modulus, for example, 900-110
It can be performed at a temperature in the range of 0 ° C. for about 1-10 hours.

According to this method, the average particle size of the crystal particles is 10
Crystallized glass in the range of 100100 nm can be obtained. The crystallized glass obtained by this method has an average particle size of crystal particles in the range of 10 to 100 nm, and preferably has an average particle size of 10 to 70 nm. The average particle size of the crystal particles can be measured using, for example, a transmission electron microscope (TEM). The crystallized glass obtained by this method can have a transmittance at a wavelength of 600 nm of 40% or more, more preferably 50%. That is, the smaller the crystal grains, the higher the transmittance,
This transmittance can be used as an index for estimating the approximate size of the crystal grains. However, since a component that affects the transmittance may be included depending on the composition of the glass, the relationship between the crystal grain size and the transmittance slightly differs depending on the composition of the glass.

The main surface of the crystallized glass substrate after the heat treatment is polished. There is no particular limitation on the polishing method.
For example, synthetic diamond, silicon carbide, aluminum oxide, synthetic abrasive grains such as boron carbide, natural diamond,
Polishing can be performed by a known method using natural abrasive grains such as cerium oxide. The main surface of the crystallized glass obtained by polishing preferably has a surface smoothness of 20 Å (2 nm) or less in average roughness Ra measured by AFM (atomic force microscope). In particular, when the crystallized glass substrate obtained by the production method of the present invention is used for a magnetic disk substrate, the average roughness Ra (2 nm or less) of this surface greatly affects the recording density of the magnetic disk, and the next step is to use a silicon wafer. When the surface is treated with an aqueous solution containing an acid, it is necessary to control the surface roughness with good controllability and to effectively remove (clean) the abrasive grains used in the polishing. Surface roughness of 20 angstroms (2n
If m) is exceeded, it becomes difficult to achieve a high recording density, and when the surface is treated with an aqueous solution containing silicic acid, uniform erosion (etching) of the continuous phase, which is an amorphous phase, will occur.
And the surface roughness cannot be controlled with good controllability. The surface roughness of the crystallized glass substrate after polishing is more preferably 15 angstrom (1.5 nm) or less, and 10 angstrom (1.0 nm), in consideration of high recording density of the magnetic disk and controllability of the surface roughness. ), Particularly preferably 5 Å (0.5 nm) or less.

The polished substrate is subjected to a surface treatment (using an etching action) using a hydrofluoric acid-containing aqueous solution to remove a part of the crystal grains contained in the crystallized glass substrate from a continuous phase on the main surface. And has a desired surface characteristic. Here, the desired surface properties are, for example, the areal density of crystal grains having a particle diameter of 10 nm or more, which protrude from the main surface and exceed 10 ⁶ / mm ² and 10 ⁹
/ mm ² or less. In particular, the surface roughness of the crystallized glass main surface subjected to the surface treatment and the conditions of the surface treatment,
It is preferable to perform the treatment so that Rmax of the main surface after the surface treatment is in the range of 1 to 60 nm. In particular, when the substrate obtained by the manufacturing method of the present invention is used for an information recording medium having a head flying height of 30 nm or less, Rmax of the main surface is in the range of 1 to 30 nm, preferably in the range of 1 to 15 nm. , More preferably 1 to
It is desirable to select the surface roughness of the crystallized glass main surface to be subjected to the surface treatment and the conditions of the surface treatment so as to be in the range of 10 nm.

The surface treatment in the production method of the present invention is performed using an aqueous solution containing silicic acid as a solution having an etching action and / or an abrasive removing (cleaning) effect. As the aqueous solution containing hydrofluoric acid, it is preferable to use the aqueous hydrofluoric acid solution described in Examples and the mixed acid aqueous solution of hydrofluoric acid and hydrofluoric acid in consideration of the control of the surface roughness. In order to control the etching rate, a surfactant or the like may be added to the surface treatment solution. As the surfactant, a commonly used surfactant can be used, and examples thereof include an anionic compound, a cationic compound, a nonionic compound, and an amphoteric compound. These surfactants can be used alone or in combination of two or more. Surface treatment conditions (concentration of silica hydrofluoric acid,
Types and concentrations of acids other than hydrofluoric acid, temperature, treatment time, etc.)
Is appropriately set so that the main surface of the substrate has the above characteristics. When the solution for surface treatment is an aqueous solution of hydrofluoric acid, its concentration is preferably 0.01 to 1.0% by weight. When the concentration of silica hydrofluoric acid is less than 0.01% by weight, the ability to corrode (etch) the continuous phase (amorphous phase) of the crystallized glass and the cleaning ability of the abrasive are reduced, and the desired surface roughness is controlled. Processing time tends to be long, 1.0
If the amount exceeds 10% by weight, the etching rate tends to be high and the control of the surface roughness tends to be difficult. It is also possible to use an aqueous solution of hydrofluoric acid or a mixed acid containing hydrofluoric acid in addition to the hydrofluoric acid as described above. In this case, the ratio (weight% ratio) between silicic acid and hydrofluoric acid in the mixed acid is 1: 1 to 10:
It is preferably 1. If the weight percentage of hydrofluoric acid is higher than that of silicic acid, the etching rate becomes too fast,
Controllability of the surface roughness tends to deteriorate. For example, a glass substrate polished to a surface roughness of 3 nm is replaced with 0.25% H ₂ SiF ₆ +0.25
% HF aqueous solution at 45 ° C for 5 minutes, the surface roughness Rmax of the glass substrate, which was 3 nm before the treatment, becomes about 8 nm.
The surface roughness Rmax of the glass substrate, which was nm, becomes about 15 nm.
For example, when a glass substrate polished to a surface roughness of 3 nm is subjected to a surface treatment at 45 ° C. for 5 minutes with a 0.25% H ₂ SiF ₆ aqueous solution (ultrasonic application), the surface roughness of the glass substrate was 3 nm before the treatment. Sa R
The max is about 6 nm, and when the surface is treated with the same etching solution at 45 ° C. for 20 minutes, the surface roughness Rmax of the glass substrate, which was 3 nm before the treatment, becomes about 9 nm. When an aqueous solution containing silicic acid is used as an etching solution, the polishing agent used for polishing can be effectively removed, and surface defects such as abnormal projections can be effectively suppressed.

The information recording medium substrate obtained by the manufacturing method of the present invention is made of crystallized glass in which crystal particles are dispersed in a continuous phase of amorphous glass. Further, at least the main surface of the substrate has a part of the crystal grains partially protruding from the continuous phase. The main surface of the substrate is a surface of the substrate surface on which the information recording layer is to be formed. Some of the fine crystal grains are exposed from the continuous phase of the glass to form projections (convex portions). That is, the substrate is a crystallized glass, which is a kind of composite material, in which amorphous glass is used as a continuous phase, and crystal particles having high rigidity and high Young's modulus are dispersed in the glass phase. A large number of fine projections are formed on the main surface.

The particle size of the crystal particles can be determined from the difference in density between the crystal particle portion and the glass portion based on a transmission electron microscope (TEM) photograph using the substrate as a sample. . The grain size of the crystal grains as referred to in the present invention means the grain size when observed from a direction perpendicular to the main surface of the substrate. That is, in the substrate obtained by the production method of the present invention, the size of the protruding crystal particles, which is the particle size when the substrate is enlarged and observed from a direction perpendicular to the main surface with a transmission electron microscope, is 1000 nm or less ( It is preferably 500 nm or less, more preferably 300 nm or less, particularly preferably 100 nm or less. However, when the shape of the crystal grains when observed from a direction perpendicular to the main surface is not circular,
The longer diameter is defined as the particle diameter.

As will be described in detail later, the projections of the crystal grains are generally smoothed on the surface of the crystallized glass by polishing.
It is formed by performing a surface treatment (etching) on the smoothed surface. Of the crystal particles present in the crystallized glass, those exposed on the surface and those not exposed on the surface but present near the surface will be partially exposed on the surface by polishing and etching. . Even if crystal grains with a small particle size are exposed on the surface during polishing and etching,
As polishing and etching progress, they fall off the surface before forming large projections. However, in the case of a crystal particle having a large particle size, polishing and etching progress, and even if the convex portion becomes high, it does not fall off the surface but becomes a high protrusion and remains on the main surface. Therefore, in the case of crystallized glass containing crystal grains having a large particle diameter, the convex portions existing on the main surface are too high, and even if an information recording layer is formed there, a medium surface having high smoothness cannot be obtained. As a result, the distance between the head for writing data on the medium and the read head for reading data written on the medium and the surface of the medium (flying distance of the head) cannot be reduced. Low flying height required for next-generation high-density information recording media (30 nm or less)
It becomes a hindrance factor.

Therefore, in the crystallized glass substrate used in the manufacturing method of the present invention, it is preferable that the crystal grains contained in the crystallized glass have a particle diameter of 1000 nm or less in order to reduce the flying height of the head. When the crystal particle size is larger than 1000 nm,
Regardless of the surface treatment method, the surface projections become too large, and the bit error tends to increase. By setting the particle size of the crystal particles to 1000 nm or less, the height of the projections exposed on the main surface of the substrate can be kept low, and a medium having a smooth surface can be obtained. A preferred crystal particle size is 700 nm or less, a more preferred crystal particle size is 300 nm or less, and further preferably 100 nm or less. The crystal grain size is preferably, for example, in the range of 10 to 300 nm according to the magnetic recording density.However, the flying distance of the magnetic head becomes smaller with the dramatic increase in the magnetic recording density.
The required crystal grain size is getting smaller and smaller. For example, when the magnetic recording density is 20 Gb / inch ² , the flying distance of the magnetic head is about 15 nm, so that the crystal grains in the substrate glass must be suppressed to 100 nm or less at the maximum.

In the manufacturing method of the present invention, as described above,
Into a glass substrate obtained by melting and molding
Generate crystal nuclei, and then heat-treat the crystal nuclei
Grow and produce crystal particles in the glass substrate. The result
The areal density of crystal grains is 10⁶Pieces / mm ^TwoExceeds and 10⁹Pieces / mm^TwoLess than
It is preferable that the particle size is 1000 nm or less
Is preferred.

By reducing the particle size of crystal grains produced by growing crystal nuclei to 1000 nm or less,
The smoothness of the main surface of the substrate can be improved. In order to reduce the flying height, it is preferable that the crystal particles projecting above the main surface have a smaller particle size. However, in a magnetic recording medium of the CSS system, etc., the height of the projections on the main surface is reduced by reducing the particle size of the crystal grains. to some extent to increase the surface density of the convex portion (10 exceeds ^six / mm ²⁾ is suitable. As a result of investigations by the present inventors, it is known that the effect of preventing the head from adsorbing is obtained when crystal grains having a particle size of 10 nm or more are exposed.
It defines the areal density of crystal grains of nm or more. When the particle size is less than 10 nm, even if it is exposed on the main surface, it does not contribute to prevention of adsorption between a write / read head (for example, a magnetic head) and the surface of an information recording medium using this substrate. The particle size of the crystal particles is preferably 10 nm or more and 500 nm or less, more preferably 10 nm or more and 30 nm or less, and particularly preferably 10 nm or more and 100 nm or less.

For the above reason, the particle size is 10 nm or more (1000 nm or less).
The area density of the crystal particles below is 10 ⁶Pieces / mm^TwoMore than
Is appropriate. However, the surface density is too high
The individual crystal particles fuse to form large crystal particles
The crystal grain size should be 1000 nm or less.
Becomes difficult. Large crystal grains are used on the substrate as described above.
This may cause a loss of the smoothness of the main surface. So, the crystal particles
Isal density of 10⁹Pieces / mm^TwoDo the following. That is, the production of the present invention
A substrate obtained by the method, wherein
Area density of crystal grains with a diameter of 10 nm or more (1000 nm or less)
Is 10⁶Pieces / mm^TwoExceeds and 10⁹Pieces / mm^TwoBelow, preferably 10
⁷Pieces / mm^TwoMore than 10⁹Pieces / mm^TwoIt is preferable to set the following.

Apart from the above-mentioned reason, a large number of crystal grains are precipitated in the crystallized glass to increase the crystallinity of the glass, to improve properties such as Young's modulus and hardness of the substrate, and to increase the rotation speed. From the viewpoint of obtaining the rigidity of the substrate corresponding to the low flying height, from the viewpoint of protruding from the main surface, the particle size is 10 nm
The areal density of crystal grains having a size of 1000 nm or less is 10 ⁶ /
Suitably, it is more than mm ² and not more than 10 ⁹ pieces / mm ² .
In order to give the substrate a certain degree of rigidity, it is necessary to increase the ratio of the volume of the crystal phase to the entire substrate. But,
In the substrate obtained by the production method of the present invention, since the particle size of the crystal particles is preferably 1000 nm or less, it is necessary to increase the number of crystal particles in order to increase the ratio of the volume of the crystal phase to the entire substrate. . Therefore, it is appropriate for the substrate obtained by the manufacturing method of the present invention that the above-mentioned surface density is larger than 10 ⁶ pieces / mm ² . However, as described above, when a large number of crystal grains are precipitated, fusion between crystal grains occurs during the heat treatment for crystallization, and abnormally large crystal grains are formed, and the main grains formed by polishing and etching are formed. Abnormal projections may be formed on the surface, which may cause problems such as an increase in signal noise and a bit error. In order to prevent such a problem, it is appropriate to set the density of crystal grains exposed on the main surface to 10 ⁹ / mm ² or less.

[0032] Of the crystal particles having a particle size of 10 nm or more,
Despite the protruding parts formed on the main surface, the measurement of the areal density on the main surface is performed by scanning the main surface of the substrate with a scanning electron microscope (SEM).
Observed by The areal density can be obtained by obtaining the number of crystal grains per 1 mm ² based on the area observed with a scanning electron microscope.

In general, the height of the projections (protrusions) on the main surface obtained by etching is preferably such that the average height is 5 to 50 nm. If the height of the protrusions (projections) on the main surface is 50 nm or less, the improvement in magnetic recording density due to the reduction in bit size is not limited. In addition, in the CSS type magnetic recording medium, if the height of the projections (projections) on the main surface is 5 nm or more, the surface characteristics of the substrate do not approach too close to that of the mirror surface,
There is no problem such as adhesion to the head. still,
In the magnetic recording medium of the LUL (load unload (ramp load)) system, no problem occurs even if the average height of the projections is less than 5 nm. In the case of the LUL type magnetic recording medium, the average height can be set to a wide range of 0.1 to 50 nm as a preferable range. However, low flying of the head,
From the viewpoint of recording density and the like, it is preferable that the average height of the protrusions is 5 to 10 nm in the case of the CSS method, and 0.
1 to 10 nm, preferably 0.1 to 2 nm, more preferably 0.1 to 1 n
m is desirable. The height of the projections of the microprojections can be measured by an atomic force microscope (AFM) or the like.
An atomic force microscope is preferable because it can measure up to the height of a very small protrusion. In addition, on the main surface, the center position of the surface roughness of the glass phase which is a continuous phase is used as a reference line, and the average height from there to the top of the convex portion (projection) made of crystal grains is the height of the convex portion. And Further, by setting the surface roughness (maximum height) Rmax of the main surface of the substrate to 1 to 30 nm, it is possible to realize a head flying height of 30 nm or less, which can support high recording density. In the production method described above, it is preferable to set the conditions of the surface treatment so as to satisfy the above. In addition, surface roughness (maximum height) Rmax
Is measured with an atomic force microscope. There is a correlation between the average roughness (maximum height) of the main surface of the substrate and the flying height of the head. To further reduce the flying height, Rmax should be 1 to 15 nm, more preferably 1 to 10 nm. desirable.

The substrate obtained by the production method of the present invention has a ratio of the total crystal grain volume in a unit volume of 15%.
Preferably it is ~ 80%. By setting the ratio of the total of the crystal particle volume to the unit volume (hereinafter, referred to as crystallinity) to 80% or less, it is possible to suppress the formation of abnormally large crystal particles due to fusion between the crystal particles. As a result, occurrence of abnormal projections on the main surface can be prevented. In addition, the crystallinity is 15
%, A substrate having high rigidity and hardness can be obtained. Measurement of crystallinity is generally known
It can be determined by the X-ray diffraction method. Preferred crystallinity is 20-75%, more preferably 20-30% or 45-75.
%.

Crystallization obtained by the production method of the present invention
The glass substrate is at least SiO_Two, A1 _TwoO_Three, MgO, TiO_TwoIncluding
It is preferable to be made of crystallized glass. Due to this composition
The number and size of crystal grains can be easily controlled.
You. In addition, polishing and post-polishing etching are performed by the crystal grains.
The surface density (the size of the protrusions
(Area density of crystal grains). The manufacturing method of the present invention
The crystallized glass substrate obtained by, for example, alkali metal
Oxide (Li_TwoO, Na_TwoOK_TwoO) and alkaline earth metal oxides (Mg
O, CaO, SrO, BaO) and transition metal oxides (NiO, ZnO, etc.)
Or A1_TwoO_Three, SiO_Two, TiO_Two, ZrO_TwoChoose from combinations etc.
It can be made of a material. However, the material
Alkaline metal oxide components as much as possible to maintain high rigidity
It is important to keep the content of. Processing characteristics
Good, small crystal grain size and high Young's modulus
The main crystal is enstatite and / or
Solid solution, α-quartz solid solution and enstatite
And / or a material containing a solid solution thereof is preferred. Former
In the case of crystallized glass, SiO_Two35-65 mol%, Ti
O_Two5 to 15 mol%, and the total of the above compositions is 92 mol% or less.
The main crystal is enstatite and / or its solid solution
In the latter case, the crystallized glass is
As the crystallized glass, the crystallized glass is SiO_TwoTo
42-65 mol%, Al_TwoO_Three11-25 mol%, MgO 15-33 mol
%, TiO_TwoContaining 5.5 to 13 mol% of α-quartz as the main crystal
Solid solution and enstatite and / or enstatite
Some contain solid solutions. Obtained by the production method of the present invention
Specific examples of crystallized glass that can constitute a crystallized glass substrate
This will be further described.

Examples of the [crystalline glass 1] crystallized glass, SiO ₂ 35 to 65 mol%, A1 ₂ O ₃ 5 to 25 mol%, the MgO 10
40 mol%, wherein the TiO ₂ 5 to 15 mol%, the total of the composition 9
Preferably there is at least 2 mol%, the molar ratio (A1 ₂ O ₃ / MgO)
Is preferably less than 0.5. The crystallized glass 1 having the above composition has suitable crystal grains, areal density, crystallinity, rigidity, excellent chemical resistance, and a metal driving system (a shaft for rotating the medium) for rotating the medium. And a jig for fixing the medium to this shaft).

In the crystallized glass 1, SiO ₂ is a glass network structure formed, and enstatite having a composition of MgO · SiO ₂ and an engine having a composition of (Mg · Al) SiO ₃ , which are main precipitated crystals. It is also a constituent of tight solid solutions. SiO ₂
If the content of is less than 35%, the melted glass is very unstable, so that high-temperature molding may not be performed, and the above-mentioned crystals may precipitate and become difficult. If the content of SiO ₂ is less than 35%, the chemical durability of the remaining glass matrix phase tends to deteriorate, and the heat resistance tends to deteriorate.
On the other hand, when the content of SiO ₂ exceeds 65%, enstatite is unlikely to be precipitated as a main crystal phase, and the Young's modulus of the glass tends to rapidly decrease. Therefore, the content of SiO ₂ is in the range of 35 to 65% in consideration of the type of precipitated crystal and the amount of the precipitated crystal, chemical durability, heat resistance, and molding / productivity.
From the viewpoint that crystallized glass having more preferable physical properties can be obtained, the content of SiO ₂ is preferably in the range of 40 to 60%.

Al ₂ O ₃ is an intermediate oxide of glass and contributes to improving the surface hardness of glass. However, when the content of Al ₂ O ₃ is less than 5%, the chemical durability of the glass matrix phase also decreases, and the strength required for the substrate material tends to be hardly obtained. On the other hand, when the content of Al ₂ O ₃ exceeds 25 mol%, precipitation of enstatite as a main crystal phase becomes difficult, and the melting temperature becomes high, so that the glass becomes difficult to melt and easily devitrified. Tends to be difficult to mold. Therefore, considering the solubility of glass, high-temperature moldability, crystal seeds and the like, the content of Al ₂ O ₃ is 5-25.
%, Preferably in the range of 7-22%.

MgO is a glass modifying component, and MgO · SiO ₂
Is a main component of crystals of enstatite and its solid solution having the following composition. If the content of MgO is less than 10%, the above crystals are unlikely to precipitate, the devitrification tendency and the melting temperature of the glass are high, and the working temperature range of the glass forming tends to be narrow. On the other hand, when the content of MgO exceeds 40 mol%, the high-temperature viscosity of the glass sharply decreases and becomes thermally unstable, so that productivity tends to deteriorate, and Young's modulus and durability tend to decrease. Therefore, the content of MgO is 10-40 in consideration of the productivity, chemical durability, high-temperature viscosity and strength of glass.
%, Preferably in the range of 12-35%.

However, it is preferable to adjust the contents of MgO and Al ₂ O ₃ so that the molar ratio (Al ₂ O ₃ / MgO) is less than 0.5. This is because when the molar ratio (Al ₂ O ₃ / MgO) is 0.5 or more, the Young's modulus of the crystallized glass tends to sharply decrease. By setting Al ₂ O ₃ /MgO<0.5, 150
Crystallized glass having a high Young's modulus of GPa or more can also be obtained. Preferably, Al ₂ O ₃ /MgO<0.45.
However, if the molar ratio of Al ₂ O ₃ / MgO is too small, the high-temperature viscosity of the glass tends to decrease and the crystal grains may increase, so the Al ₂ O ₃ / MgO ratio is 0.2 or more, preferably Suitably, it is at least 0.25.

TiO ₂ is a nucleating agent for crystal phase precipitation of enstatite having a composition of MgO · SiO ₂ and enstatite solid solution having a composition of (Mg · Al) SiO ₃ . In addition, TiO ₂
When the content of SiO ₂ is small, it also has the effect of suppressing the devitrification of glass. However, when the content of TiO ₂ is less than 5%, the effect as a nucleating agent of the main crystal is not sufficiently obtained, the glass is crystallized on the surface, and the production of a homogeneous crystallized glass tends to be difficult. is there. On the other hand, if the content of TiO ₂ exceeds 15%, the high-temperature viscosity of the glass becomes too low, causing phase separation,
Glass productivity tends to be extremely deteriorated due to devitrification. Therefore, glass productivity, chemical durability,
Considering high-temperature viscosity, crystal nucleation and the like, the content of TiO ₂ is suitably in the range of 5 to 15%, preferably in the range of 5.5 to 14%.

In the crystallized glass 1, Y ₂ O ₃ is not an essential component, but, for example, by introducing 2% of Y ₂ O ₃ , the Young's modulus of the crystallized glass can be increased by about 10 GPa and the liquid phase The temperature can be reduced by about 50-100 ° C. That is, by introducing a small amount of Y ₂ O ₃ , the properties and productivity of the glass can be remarkably improved, and if the content of Y ₂ O ₃ is 0.3% or more, the effect of Y ₂ O ₃ can be obtained. . The content of Y ₂ O ₃ is preferably at least 0.5%. However, Y ₂ O ₃ has the power to suppress the growth of the main crystal contained in the above-mentioned glass. for that reason,
If the content of Y ₂ O ₃ is too large, the surface crystallization tends to occur in the heat treatment performed for the purpose of crystallizing the glass, and the target crystallized glass tends not to be produced. From such a viewpoint, the content of Y ₂ O ₃ is suitably set to 10% or less. In particular, the content of Y ₂ O ₃ is preferably at most 8%, more preferably at most 3%.

The crystallized glass 1 can contain ZrO ₂ . ZrO ₂ enhances the stability of the glass,
It can play a large role in improving the stability of glass containing a large amount of gO. It also acts as a nucleating agent,
As an assistant to iO ₂ , it can promote glass phase separation during pretreatment and contribute to refinement of crystal grains. But,
If the content of ZrO ₂ exceeds 6%, the high-temperature melting property and homogeneity of the glass may be deteriorated. Therefore, the amount of ZrO ₂ is suitably 6% or less. Furthermore, considering the high-temperature melting property of glass and the homogeneity of crystal particles, ZrO
The introduction amount of ₂ is preferably 5% or less.

The crystallized glass 1 is made of SiO ₂ , Al ₂ O ₃ , M from the viewpoint of maintaining characteristics such as high Young's modulus and uniform crystallinity.
The total of gO and TiO ₂ is 93% or more. SiO ₂ , Al
The sum of ₂ O ₃ , MgO and TiO ₂ is preferably at least 95%.

Within the above range, as other components, alkali metal oxides (for example, Li ₂ O, Na ₂ O, K ₂ O, etc.) and so on as long as the desired properties of the crystallized glass are not impaired. /
Or alkaline earth metal oxides (e.g., CaO, SrO, BaO)
And the like. As the alkali metal oxide and / or the alkaline earth metal oxide, nitrate can be used as a glass raw material. When Sb ₂ O ₃ is used as a defoaming agent during glass production, platinum is easily mixed into the glass from the glass melting platinum crucible, and nitrate is used as a glass raw material to prevent platinum from being mixed into the glass. Can be. The content of each of the alkali metal oxide and the alkaline earth metal oxide is preferably 0.1 mol% or more from the viewpoint of obtaining the above effects. However, when an alkali metal oxide is contained, the content of the alkali metal oxide is appropriately set to 5 mol% or less since the alkali metal oxide tends to lower the Young's modulus. In the case where an alkaline earth metal oxide is contained, the content of the alkaline earth metal oxide is suitably 5 mol% or less since the crystal grains tend to be large. When containing an alkali metal oxide, K ₂ O is particularly preferably 0.1 to 5 mol%, preferably 0.1 to 2 mol%, more preferably 0.1 to 1 mol%. When containing an alkaline earth metal oxide, particularly 0.1 to 5 mol%, preferably 0.1 to 5 mol%
2 mol% SrO is preferred.

In order to homogenize the glass, As ₂ O ₃ and / or Sb ₂ O ₃ can be contained as a defoaming agent. Depending on the high temperature viscosity, which varies with the composition of the glass,
By adding an appropriate amount of As ₂ O ₃ , Sb ₂ O ₃ or As ₂ O ₃ + Sb ₂ O ₃ to the glass, a more homogeneous glass can be obtained. However, if the amount of the defoaming agent is too large, the specific gravity of the glass tends to increase and the Young's modulus tends to decrease, and may react with the platinum crucible for melting to damage the crucible. Therefore, it is appropriate that the addition amount of the defoaming agent is 2% or less, preferably 1.5% or less. In addition to the above basic components, impurities in the raw material, for example, Cl, F, SO _{3 and the} like as glass fining agents are contained if they are 1% or less, respectively, without impairing the properties of the crystallized glass of the present invention. be able to. Further, it is desirable that the crystallized glass 1 does not contain ZnO and NiO. ZnO is used to facilitate formation of spinel, which is a hard crystal. Further, it is not desirable to include NiO from the viewpoint of facilitating the formation of spinel and from the viewpoint of being a component that affects the environment.

The main crystal phase in the crystallized glass 1 is, for example, enstatite (including enstatite solid solution) having a composition of MgO.SiO ₂ and (Mg.Al) SiO ₃ . Also,
Enstatite includes clinoenstatite, protoenstatite and enstatite. Further, in addition to the above crystals, other crystals such as titanate, mullite, fosterite, cordierite and the like can be contained. Since enstatite has low hardness (Mohs hardness of 5.5), crystallized glass containing enstatite as a main crystal is very easy to polish, and a desired surface roughness can be obtained in a relatively short time. There are features. Furthermore, enstatite, from its chain or layered crystal shape,
It is thought that a high Young's modulus can be obtained even if the particle size is small, with the glass component entering the gap. The crystallized glass 1 does not substantially contain spinel. Spinel
Since it is a hard crystal (Mohs hardness 8) as compared with enstatite, it is conceivable that the effect of easy polishing is impaired. Further, the crystallized glass 1 does not substantially contain a quartz solid solution.

In the crystallized glass 1, the main crystal phase is a glass phase containing 50% by volume or more of crystals (crystals whose type can be specified by X-ray diffraction). In the crystallized glass 1, in most cases, enstatite and / or a solid solution thereof is 70% by volume or more of the crystal,
In some cases, the content is 80% by volume or more, and more preferably 90% by volume or more. In the crystallized glass 1, the ratio of crystals in the glass is approximately 20 to 70.
%. Furthermore, the average value of the size (particle size) of the crystals contained in the crystallized glass 1 is preferably 0.5 μm or less, more preferably 0.3 μm or less, and preferably 0.1 μm or less. More preferred. The average value of the grain size of the crystals contained in the crystallized glass of the present invention is most preferably 50 nm or less. When the average value of the crystal grain size exceeds 0.5 μm, not only the mechanical strength of the glass is reduced, but also the crystal may be lost during the polishing process, and the surface roughness of the glass may be deteriorated. Control of the particle size of such crystal particles can be mainly performed by the type of the included crystal phase and the heat treatment conditions described below.
The above-mentioned fine crystal particles can be obtained under the heat treatment conditions under which the main crystal phase of enstatite and / or a solid solution thereof, which is an essential component in the crystallized glass 1, is obtained.

[0049] As the [crystalline glass 2 crystallized glass, SiO ₂ forty-two to sixty-five mol%, A1 ₂ O ₃ and 11 to 25 mol%, the MgO 15
It is preferable to contain 3333 mol% and 5.5-13 mol% of TiO ₂ . The crystallized glass 2 preferably contains enstatite and / or a solid solution thereof as a main crystal. The crystallized glass 2 has a suitable crystal particle, surface density, crystallinity, rigidity, excellent chemical resistance, a metal driving system for rotating the medium (an axis for rotating the medium and an axis for rotating the medium. There is an advantage that the thermal expansion coefficient can be easily matched with the jig for fixing the medium.

Specific examples of the above-mentioned crystallized glass 2 include the following crystallized glass. Crystallized glass substrate 2-1 SiO ₂ : 42-65 mol%, Al ₂ O ₃ : 11-25 mol%, MgO: 15-33
A crystallized glass containing, by mol%, and TiO ₂ : 5.5-13 mol%, wherein the main crystal phase contains α-quartz solid solution and enstatite and / or enstatite solid solution. Crystallized glass 2-2 SiO ₂ : 42-65 mol%, Al ₂ O ₃ : 11-25 mol%, MgO: 15-33
Mol%, and TiO _2: 5.5-13 containing mol%, alpha-quartz comprises a solid solution and enstatite and / or enstatite solid solution, alpha-quartz solid solution, enstatite and enstatite total solid solution 50 wt% or more Is a crystallized glass. Crystallized glass 2-3 SiO ₂ : 42-65 mol%, Al ₂ O ₃ : 11-25 mol%, MgO: 15-33
And TiO ₂ : 5.5-13 mol%, and the main crystal phase is a quartz-based crystal in which a diffraction pattern substantially equivalent to a diffraction pattern specific to quartz is observed in an X-ray diffraction pattern, and enstatite and And / or a crystallized glass containing an enstatite solid solution and having a specific gravity of 2.9 or more. Crystallized glass 2-4 SiO _2: 42-65 mol%, Al ₂ O _3: 11-25 mol%, MgO: 15-33
Mol%, and TiO ₂ : 5.5-13 mol%, and the crystal phase is
X-ray diffraction patterns include quartz-based crystals and enstatite and / or enstatite solid solution in which a diffraction pattern substantially equivalent to the diffraction pattern specific to quartz is observed, and the total of quartz-based crystals, enstatite and enstatite solid solution is A crystallized glass having 50% by weight or more and a specific gravity of 2.9 or more.

In the crystallized glass 2, SiO ₂ is a formation of a network structure of glass, and is also a component of α-quartz solid solution or quartz-based crystal and enstatite, which are main precipitated crystals. When the content of SiO ₂ is less than 42%, precipitation of α-quartz solid solution crystals or quartz-based crystals becomes difficult, and as a result, a crystallized glass having high expansion characteristics cannot be obtained. Also,
When the content of SiO ₂ is less than 42%, the chemical durability of the remaining glass matrix phase tends to deteriorate, and the heat resistance tends to deteriorate. On the other hand, when the content of SiO ₂ exceeds 65%, the Young's modulus of the glass may be sharply reduced. Therefore,
The content of SiO ₂ is suitably in the range of 42 to 65%, preferably 44 to 60%, in consideration of the precipitated crystal seeds and the amount of precipitation, chemical durability, heat resistance and molding / productivity. Range.

MgO is an extremely important component that generates enstatite crystals by heat treatment of the raw glass together with the SiO ₂ component and has the effect of maintaining high Young's modulus while improving strength and heat resistance. However, if the content of MgO is less than 15%, the above effects cannot be obtained.
% Or more. On the other hand, when the content of MgO exceeds 33%, a high expansion α-quartz solid solution crystal or a quartz-based crystal hardly precipitates from glass, and high expansion characteristics cannot be obtained. So, Mg
The amount of O introduced should be 33% or less. The content of MgO is suitably in the range of 15 to 33%, and preferably in the range of 17 to 32%, in consideration of productivity of glass, chemical durability, high-temperature viscosity and precipitated crystal seeds. is there.

Al ₂ O ₃ is an intermediate oxide of glass and is also a component of α-quartz solid solution or quartz-based crystal which is a main crystal seed. The introduction of Al ₂ O ₃ promotes precipitation of α-quartz solid solution crystals or quartz-based crystals, and contributes to improvement of the glass surface hardness. If the content of Al ₂ O ₃ is less than 11%, the high expansion α-
While precipitation of quartz solid solution or quartz crystal becomes difficult,
Young's modulus of the obtained crystallized glass also tends to be small. However, when the content of Al ₂ O ₃ exceeds 25%, precipitation of enstatite having a high Young's modulus becomes difficult, and the high-temperature viscosity and high-temperature solubility of the glass are undesirably deteriorated. Therefore, the content of Al ₂ O ₃ is suitably in the range of 11 to 25%, and preferably in the range of 12 to 22%, in consideration of the solubility of glass, high-temperature viscosity, precipitated crystal seeds, and the like. It is.

In the crystallized glass 2, SiO_TwoAnd Al_TwoO_ThreeIf
Total (SiO_Two+ Al_TwoO_Three) Is at least 58 mol% and at most 80 mol%
It is preferred that (SiO_Two+ Al_TwoO_Three) Is less than 58 mol%
Hardly precipitates α-quartz solid solution or quartz-based crystal
Become. (SiO_Two+ Al_TwoO_Three) Exceeds 80 mol%, the Young's modulus
Tends to decrease. (SiO_Two+ Al_TwoO_Three) Is preferably 60
%, More preferably at least 62 mol%. Also,
(SiO_Two+ Al_TwoO_Three) Is preferably 75 mol% or less, more preferably
Or less than 73 mol%. Furthermore, the crystallized glass 2
MgO and (SiO_Two+ Al_TwoO_Three) Molar ratio MgO / (SiO_Two+ Al _TwoO_Three) Is
It is preferably 0.125 or more and 0.55 or less. Molar ratio Mg
O / (SiO_Two+ Al_TwoO_Three) Is less than 0.125, the Young's modulus decreases
Tend to Molar ratio MgO / (SiO_Two+ Al_TwoO_Three) Exceeds 0.55
Expansion coefficient tends to be small. Molar ratio MgO / (SiO_Two
+ Al_TwoO_Three) Is preferably 0.2 or more, more preferably 0.3 or more
It is. In addition, the molar ratio MgO / (SiO_Two+ Al_TwoO_Three) Is preferably
It is 0.5 or less, more preferably 0.4 or less.

[0055] TiO ₂ is a component indispensable to the precipitation of crystal grains, such as α- quartz solid solution or quartz-based crystals and enstatite as formers of crystal nuclei, and when the content of SiO ₂ is small, the glass thermal It is also an important component that gives a good stability. If the content of TiO ₂ is less than 5.5%, the glass cannot serve as a nucleating agent for the main crystal, and the glass is crystallized on the surface, making it difficult to produce a homogeneous crystallized glass. However, when the content of TiO ₂ exceeds 13%, precipitation of a high expansion α-quartz solid solution or quartz-based crystal becomes difficult, but the high temperature viscosity of the glass becomes too low to cause phase separation or devitrification. Therefore, the productivity of the glass tends to be extremely deteriorated. Therefore, the content of TiO ₂ is suitably in the range of 5.5 to 13%, and preferably in the range of 6.5 to 12%, in consideration of productivity of glass, high-temperature viscosity, generation of crystal nuclei, and the like.

In the crystallized glass 2, ZrO ₂ can be introduced in addition to the above components. ZrO ₂ is a component added for adjusting the high-temperature viscosity and stability of glass. Small amount
When ZrO ₂ is introduced, the glass can be more easily manufactured by improving the thermal stability of the glass or increasing the high-temperature viscosity of the melt. However, when the content of ZrO ₂ exceeds 4%, the high-temperature melting property of the glass is deteriorated and the precipitation of the main crystal is inhibited, which is not desirable. Therefore, the amount of ZrO ₂ introduced is
It is appropriate that the content be 4% or less, and preferably 3% or less.

The crystallized glass 2 contains Y in addition to the above components._TwoO_ThreeTo
Can be introduced. In the crystallized glass 2, 1
% Y_TwoO_ThreeBy introducing crystallized glass
The liquidus temperature by about 50 ° C.
Can be Furthermore, Y_TwoO _ThreeThe introduction of glass
In addition to improving thermal stability, α-quartz solid
It also contributes to the precipitation of solution or quartz-based crystals. But Y_Two
O_ThreeHas the power to suppress the nucleation of the titanate,
Y_TwoO_ThreeIf too much is introduced, the glass will
Surface crystallization occurs and the target crystallized glass cannot be made
In some cases. Therefore, Y_TwoO_ThreeContent ranges from 0.1 to 5%
It is preferable that Especially Y_TwoO_ThreeContent is in the range of 0.2-4%
More preferably, it is an enclosure.

In addition to the above components, Li ₂ O, Na ₂ O, K ₂ O, CaO, SrO, BaO, Fe ₂ O, as long as desired properties are not impaired.
₃ , up to 5% of rare earth metal oxide components such as Ga ₂ O ₃ , B ₂ O ₃ , P ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ and La ₂ O ₃ are added to the crystallized glass 2. sell. However, since these components significantly lower the Young's modulus of the glass and hinder the precipitation of the main crystal, it is desirable to suppress the amount of the components to 5% or less. Further, considering the productivity of glass, the content is more preferably 4% or less.

As ₂ O ₃ and Sb ₂ O ₃ are components added as defoaming agents to homogenize the original glass. Appropriate amount of As ₂ O ₃ , Sb ₂ O ₃ or As ₂ O ₃ + S according to high temperature viscosity of each glass
Adding b ₂ O ₃ to the glass results in a more homogeneous glass. However, if the amount of these defoamers is too large, the specific gravity of the glass tends to increase and the Young's modulus tends to decrease, and it may react with the melting platinum crucible and damage the crucible. is there. So, as ₂ O
It is preferable that the addition amount of ₃ + Sb ₂ O _{3 be} 2% or less. In particular, the addition amount of As ₂ O ₃ + Sb ₂ O ₃ is preferably 1.5% or less.

The main crystal phase in the crystallized glass 2-1 is:
For example, MgO.SiO ₂ and (Mg.Al ) Includes an enstatite (including enstatite solid solution) crystal phase having a composition of SiO ₃ , or α-quartz solid solution or quartz-based crystal. In some cases, enstatite is not included and only enstatite solid solution is included. Further, enstatite includes clinoenstatite, protoenstatite and enstatite. α-quartz solid solution is, for example, 2MgO 2 Al ₂ O _{3
5SiO 2, MgO · Al 2 O} 3 · 3SiO 2 and can be selected from _{MgO · Al 2 O 3 · 3SiO} 2. Note that the main crystal phase is a crystal in the glass (a crystal whose type can be specified by X-ray diffraction) which is larger than other crystal phases. Crystallized glass 2-1
In the above, the total of α-quartz solid solution and enstatite (including enstatite solid solution) which are main crystals is 50% by volume or more. The crystallized glass 2-2 is, for example,
MgO ・ SiO ₂ and (Mg ・ Al ) It contains an enstatite (including enstatite solid solution) crystal phase having a composition of SiO ₃ and α-quartz solid solution in a total of 50% by volume or more.

In the crystallized glasses 2-3 and 2-4 of the present invention, a quartz-based crystal in which, as a crystal phase, a diffraction pattern substantially equivalent to a diffraction pattern specific to quartz is observed in an X-ray diffraction pattern; Contains enstatite and / or enstatite solid solution. Furthermore, this crystallized glass
The specific gravity can be 2.9 or more. The crystallized glass substrate 2-3 contains a quartz-based crystal and enstatite and / or enstatite solid solution as a main crystal phase. In this case, the main crystal phase is an essential crystal phase for obtaining the effect of the present invention, and compared with other crystal phases in the crystals (crystals whose type can be specified by X-ray diffraction) in the glass. Many crystals. The crystallized glass substrate 2-4 contains quartz-based crystals and enstatite and / or enstatite solid solution in an amount of 50% by volume or more.

Further, the crystallized glasses 2-3 and 2-4 are:
Specific gravity is 2.9 or more. A quartz-based crystal in which a diffraction pattern almost equivalent to that specific to quartz is observed in the X-ray diffraction pattern is one in which other oxide molecules are dissolved in a solid solution while almost maintaining the crystal system of quartz. It is conceivable that, for this reason, a diffraction pattern almost equivalent to the diffraction pattern specific to quartz is observed in the X-ray diffraction pattern. For this reason, the specific gravity is 2.9 or more, which is larger than that of crystallized glass containing quartz crystals instead of quartz-based crystals. The upper limit of the specific gravity of the crystallized glasses 2-3 and 2-4 is about 3.5. The crystallized glass 2 generally has a specific gravity of between 3.0 and 3.2.

Further, in addition to the above-mentioned main crystal phase, a small amount of other crystals such as spinel, mullite, fosterite, cordierite, titanate and the like can be contained. Titanate can act as a crystal nucleus for enstatite and α-quartz solid solutions or quartz-based crystals. The crystallized glass 2 contains, for example, about 40% by volume of α-quartz solid solution or quartz-based crystal,
About 2 enstatite (including enstatite solid solution)
5-30% by volume, the titanate can be about 10-15% by volume. In the crystallized glass 2, the ratio of crystals in the glass is preferably about 20% or more. However, if the proportion of crystals in the glass exceeds 80%, the crystal particle size tends to increase, which is not preferable. The proportion of crystals in the glass is preferably in the range of 40-80%, especially 45-80%.

The particle diameter of the crystals (enstatite, a solid solution thereof and / or α-quartz solid solution or quartz crystal) contained in the crystallized glass 2 is preferably in the range of 10 to 1000 nm. The range is more preferably from 10 to 700 nm, still more preferably from 10 to 300 nm, and particularly preferably from 10 to 100 nm. The average value of the crystal particle diameter is 1000 nm (1 μm)
By being less than or equal to the above, the mechanical strength of the glass is not reduced, and the surface roughness of the glass is not deteriorated due to the lack of crystals during polishing.

[Crystalized Glass 3] As crystallized glass, SiO ₂ : 42-65 mol%, Al ₂ O ₃ : 0-15 mol%, MgO: 5
-30 mol%, Y ₂ O ₃ : 0.5-8 mol%, Li ₂ O: more than 10 mol% and 25 mol% or less, and the main crystal phase is β-quartz solid solution and / or enstatite Crystallized glass 3 is preferred.

In the crystallized glass 3, SiO ₂ is a formation of a network structure of glass, and is also a component of β-quartz solid solution and enstatite, which are main precipitated crystals. Although not a main crystal, it is also a component of β-spodumene solid solution. If the content of SiO ₂ is less than 42%, the melted glass is unstable, so there is a tendency that high-temperature molding cannot be performed, and it becomes difficult to precipitate the above crystals as main crystals. Further, when the content of SiO ₂ is less than 42%, the chemical durability of the remaining glass matrix phase deteriorates, and the heat resistance also tends to deteriorate. On the other hand, when the content of SiO ₂ exceeds 65%, the Young's modulus of the glass tends to rapidly decrease. Thus, the content of SiO ₂ is in the range of 42 to 65% in consideration of the precipitated crystal seeds and the amount of the precipitated crystal, Young's modulus, chemical durability, heat resistance and molding / productivity, and the lower limit is preferably It is at least 45%, more preferably at least 48%, and the upper limit is preferably at most 62%, more preferably at most 60%.

Al ₂ O ₃ is an intermediate oxide of glass and also a component of β-quartz solid solution, which is a main crystal seed. Al ₂ O
The introduction of ₃ promotes the precipitation of metastable β-quartz solid solution crystals,
Contributes to improvement of glass surface hardness. However, when the content of Al ₂ O ₃ exceeds 15%, the melting temperature and the liquidus temperature increase, so that the glass becomes difficult to melt and is difficult to mold.
Therefore, the content of Al ₂ O ₃ is set to 15% or less. Soluble glass, high temperature moldability, considering that such precipitated crystals species, the content of Al ₂ O ₃ is in the range from 0 to 15% lower limit is preferably 1% or more, more preferably 2% or more And the upper limit is preferably 10% or less, more preferably 7% or less. Further, the content of SiO ₂ + Al ₂ O ₃ is preferably 50% or more, more preferably 55% or more, from the viewpoint of giving the glass a high-temperature viscosity that can be formed.

MgO forms β-quartz solid solution and enstatite crystal by heat treatment of raw glass together with SiO ₂ component,
It is a very important component having the effect of maintaining transparency while improving hardness and heat resistance. However, if the content of MgO is less than 5%, the above effects cannot be obtained. Furthermore, when the content of MgO decreases, the tendency of devitrification of the glass and the melting temperature also increase, so the content of MgO is set to 5% or more. On the other hand, when the content of MgO exceeds 30 mol%, the liquidus temperature of the glass rapidly increases, and the productivity and workability also deteriorate. Therefore, the content of MgO is set to 30% or less. The content of MgO is in the range of 5 to 30% in consideration of productivity, melting property and mechanical strength of the glass, and the lower limit is preferably 7% or more, more preferably 10% or more, and the upper limit. Is preferably 25% or less, more preferably 20% or less.

The crystallized glass 3 contains Y ₂ O ₃ . By introducing at least 0.5% of Y ₂ O ₃ , the Young's modulus of the crystallized glass is increased by about 5 GPa, and the liquidus temperature is raised to 50 ° C.
To some extent. In addition, at least 0.5%
The introduction of Y ₂ O ₃ can also improve the thermal stability of the glass. Thus, by introducing a small amount of Y ₂ O ₃ , the properties and productivity of the glass can be remarkably improved. However, since Y ₂ O ₃ also has the function of suppressing the nucleation of the above glass main crystal, if the introduction amount of Y ₂ O ₃ becomes too large, the glass undergoes surface crystallization during heat treatment, and the target There is a tendency that it is difficult to obtain crystallized glass having surface smoothness. Therefore, the content of Y ₂ O ₃ is set to 8% or less. The lower limit of the content of Y ₂ O ₃ is preferably 0.5%, more preferably 1%. The upper limit of the content of Y ₂ O ₃ is
Preferably it is 5%, more preferably 3%.

Li ₂ O is a component that produces a crystal such as β-quartz solid solution or β-spodumene solid solution by heat treatment of the raw glass together with SiO ₂ , and has the effect of lowering the liquidus temperature and the crystallization temperature of the glass. If the content of Li ₂ O is 10% or less, the above effects cannot be obtained. Furthermore, the content of Li ₂ O
If it is less than 10%, the melting temperature of the glass will be high, and the working temperature range of the glass disk molding will be narrow. Therefore,
Suitably, the content of Li ₂ O exceeds 10%. On the other hand, L
When the content of i ₂ O exceeds 25%, the glass becomes very unstable, and the Young's modulus of the obtained crystallized glass tends to decrease significantly. Therefore, the content of Li ₂ O is set to 25% or less. In consideration of productivity, chemical durability and mechanical properties of glass, the lower limit of the content of Li ₂ O is preferably 10.5% or more, more preferably 11% or more. Further, the upper limit of the content of Li ₂ O is preferably 22% or less, more preferably 20% or less.

The crystallized glass 3 contains one or both of β-quartz solid solution and enstatite as a main crystal phase. The crystal phase of β-quartz solid solution is 2MgO ・ 2Al ₂ O ₃・ 5SiO ₂ , M
_{gO · Al 2 O 3 · 3SiO} 2, and has one or more compositions selected from the group consisting of _{MgO · Al 2 O 3 · 4SiO} 2 is metastable quartz (quartz solid solution). Further, the crystal phase of enstatite can be, for example, a clinoenstatite crystal phase having a composition of Mg ₂ Si ₂ O ₆ . Further, the crystallized glass 3 can also contain other crystals such as a β-spodumene solid solution as a crystal phase in addition to the above crystals.

The crystal grain size of the above crystals contained in the crystallized glass 3 is such that the crystallized glass of the present invention has a surface roughness Ra of 0.1.
It is preferable that the polished surface can be formed so as to be in the range of −0.9 nm, more preferably the crystal particle diameter of the crystal phase, and the polished surface such that the surface roughness Ra is in the range of 0.1-0.5 nm. Can be formed. When the crystal particle diameter of the crystal phase contained in the crystallized glass falls within the above range, an information recording disk having excellent surface smoothness can be provided.

In the crystallized glass 3, the composition of the glass is preferably selected so that the liquidus temperature of the raw glass is 1200 ° C. or less. More preferably, it is selected such that the liquidus temperature of the raw glass is 1150 ° C. or less. The low liquidus temperature of the raw glass facilitates the production of a crystallized glass substrate. That is, in the process of melting the raw materials performed when manufacturing the glass substrate, in the steps of molding, etc., it is not necessary to use a remarkably high temperature, so that the range of adoption of the material of the melting furnace and the forming die is widened and the manufacturing becomes easy. There is an advantage to say.

TiO ₂ , ZrO ₂ , and P ₂ O ₅ all act as crystal nucleus generating agents, and promote the precipitation of fine crystal particles such as β-quartz solid solution and enstatite. Also, when the content of SiO ₂ is relatively small, it is a component that imparts thermal stability to the glass. Therefore, the crystallized glass 3 is made of Ti
It preferably contains at least one of O ₂ , ZrO ₂ , and P ₂ O ₅ . In that case, if the total content of TiO ₂ + ZrO ₂ + P ₂ O ₅ is less than 5%, the effect as a nucleating agent of the main crystal is not sufficiently obtained, the glass is surface crystallized, and homogeneous crystallization is performed. Glass fabrication tends to be difficult. Therefore, TiO ₂ , ZrO ₂ , and P ₂
It is preferable that the total content of O _{5 be} 5% or more. On the other hand, if the total content of TiO ₂ , ZrO ₂ , and P ₂ O ₅ exceeds 18%, the high-temperature viscosity of the glass becomes too low, causing phase separation or devitrification. There is a tendency to be extremely deteriorated. Therefore, the total content of TiO ₂ + ZrO ₂ + P ₂ O ₅ is preferably 18% or less. Glass productivity, chemical durability, high temperature viscosity, considering that such crystal nucleation, the total content of _{TiO 2 + ZrO 2 + P 2} O 5 , as described above 5 to 1
It is preferably in the range of 8%. The lower limit of the total content of TiO ₂ + ZrO ₂ + P ₂ O ₅ is preferably 6% or more, more preferably 7%.
The upper limit is preferably 15% or less, more preferably 13% or less.

Alkali and alkaline earth metal oxide components such as Na ₂ O, K ₂ O, CaO, SrO, BaO, ZnO, and NiO mainly adjust the high-temperature viscosity of glass, suppress the tendency of devitrification, Is a component that can be homogenized. By adding at least one of these components to the glass, the Young's modulus of the glass is somewhat reduced, but other properties of the glass, such as improving the productivity of the glass and homogenizing the size of the crystallized particles, Can be improved. Considering properties such as Young's modulus of glass, productivity, surface smoothness and strength of crystallized glass, Na
The content of ₂ O 0 to 10% of the range, the content of K ₂ O is in the range of 0 to 10%, and the content of Na ₂ O + K ₂ O is preferably 10% or less. The contents of Na ₂ O, K ₂ O and Na ₂ O + K ₂ O are all preferably 8% or less. Similarly, the content of CaO is in the range of 0-10%, the content of SrO is in the range of 0-10%, the content of BaO is in the range of 0-10%, and the content of ZnO is 0-10%.
%, The content of NiO is in the range of 0-10%, and
The content of O + SrO + BaO + ZnO + NiO is preferably at most 10 mol%. Furthermore, CaO, SrO, BaO, ZnO, NiO and CaO
The content of + SrO + BaO + ZnO + NiO is preferably at most 8%.

In addition to the above components, the crystallized glass 3 contains B ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ and
A rare earth metal oxide component such as La ₂ O ₃ can be contained. However, these components significantly reduce the Young's modulus of the glass. Accordingly, B ₂ content of O ₃ in the range of 0-5%, R ₂
The content of O ₃ is in the range of 0-5% (where R is a rare earth metal ion (for example, Nd ³⁺ , Pr ³⁺ , Pm ³⁺ , Sm ³⁺ , Eu ³⁺ , Gd ³⁺ , Tb ^3
3+ , Dy ³⁺ , Ho ³⁺ , Er ³⁺ , Tm ³⁺ , Yb ³⁺ )), the content of CeO ₂ is in the range of 0-5%, and the content of N ₂ O ₅ is 0- 5% (where N is Nb or Ta), and B ₂ O ₃ + R ₂ O ₃ +
Preferably, CeO ₂ + N ₂ O ₅ ≦ 5 mol%. further,
In consideration of the productivity of glass, the content of each of the above components and the total content are more preferably 4% or less.

As ₂ O ₃ and Sb ₂ O ₃ are components added as defoaming agents in order to homogenize glass as a raw material of crystallized glass. An appropriate amount of As ₂ O according to the high temperature viscosity of each glass
_By adding one or both of ₃ and Sb ₂ O ₃ to the glass,
A more homogeneous glass is obtained. However, when the amount of the defoamer added is too large, the specific gravity of the glass tends to increase and the Young's modulus tends to decrease, and the glass may react with the melting platinum crucible and damage the crucible. Therefore, the content of As ₂ O ₃ is in the range of 0 to ₂ %, and the content of Sb ₂ O ₃ is 0%.
It is preferred that the content be in the range of −2% and that As ₂ O ₃ + Sb ₂ O ₃ ≦ 2 mol%. In particular, the content of each of As ₂ O ₃ , Sb ₂ O ₃ and As ₂ O ₃ + Sb ₂ O ₃ is preferably 1.5% or less.

[Crystallized glass 4] As crystallized glass, SiO ₂ : 35-55 mol%, Al ₂ O ₃ : 0 mol% or more,
Less than 5 mol%, provided that SiO ₂ + Al ₂ O ₃ ≧ 40 mol%, MgO: 2
5-45 mol%, Y ₂ O _3: 0.5-8 mol%, ZrO _2: 0-
Crystallized glass 4 containing 10 mol%, TiO ₂ : 0-12 mol%, wherein ZrO ₂ + TiO ₂ : 4.5-18 mol%, and the main crystal phase is enstatite and / or β-quartz solid solution It is preferable that

In the crystallized glass 4, SiO ₂ is a formed product of a glass network structure, and is also a constituent component of enstatite and β-quartz solid solution, which are main precipitated crystals. If the content of SiO ₂ is less than 35%, the melted glass is very unstable, so that high-temperature molding tends to be impossible, and the above-mentioned crystals also become difficult to precipitate. In addition, the content of SiO ₂ is 35
If the amount is less than 10%, the chemical durability of the remaining glass matrix phase deteriorates, and the heat resistance may also deteriorate. on the other hand,
When the content of SiO ₂ exceeds 55%, the Young's modulus of the glass tends to sharply decrease. Therefore, in consideration of the precipitated crystal seeds and the amount of precipitation, chemical durability, heat resistance, and molding / productivity, the lower limit of the content of SiO ₂ is 35%, and the upper limit is 55%. The lower limit of the content of SiO ₂ is preferably 37%,
More preferably, it is 40%. Further, the upper limit of the content of SiO ₂ is preferably 54%, more preferably 53%.

Al ₂ O ₃ is an intermediate oxide of glass and is also a component of β-quartz solid solution of the main crystal seed. The introduction of Al ₂ O ₃ promotes the precipitation of metastable β-quartz solid solution crystals and contributes to the improvement of the glass surface hardness. However, when the content of Al ₂ O ₃ is 5% or more, the melting temperature and the liquidus temperature are increased, so that the glass is hardly melted and the glass is hardly formed. Therefore, the content of Al ₂ O ₃ is set to less than 5%. In consideration of the solubility of glass, high-temperature moldability, crystal seeds, and the like, the lower limit of the Al ₂ O ₃ content is preferably 0%, and more preferably 1%. The upper limit of the content of Al ₂ O ₃ is preferably 4.5%, more preferably 4%. As described above, Al ₂ O ₃ may not necessarily be contained, but from the viewpoint of imparting sufficient chemical durability to glass and thermal stability that can be mass-produced, SiO ₂ and Al ₂ O ₃ are used. Total content (SiO ₂
+ Al ₂ O ₃ ) is at least 40 mol%. Therefore, when Al ₂ O ₃ is not contained, the content of SiO ₂ is set to 40 mol% or more. Further, the total content of SiO ₂ and Al ₂ O ₃ is preferably at least 42 mol%.

MgO is a component having an effect of generating enstatite crystals by heat treatment of the raw glass together with the SiO ₂ component and maintaining transparency while improving hardness and heat resistance.
If the MgO content is less than 25%, the above effects cannot be obtained. Therefore, the content of MgO is set to 25% or more. On the other hand, Mg
If the O content exceeds 45 mol%, the high-temperature viscosity of the glass rapidly decreases, becomes thermally unstable, and the productivity and workability tend to deteriorate. Therefore, the content of MgO is set to 45% or less. The lower limit of the content of MgO is given in consideration of glass productivity, chemical durability, high temperature viscosity and strength, etc.
25%, with an upper limit of 45%. The lower limit is preferably 28
%, More preferably 32%, the upper limit is preferably 43%,
More preferably, it is 42%.

The crystallized glass 4 contains Y ₂ O ₃ . By introducing at least 0.5% of Y ₂ O ₃ , the Young's modulus of the crystallized glass is increased by about 5 GPa, and the liquidus temperature is raised to 50 ° C.
To some extent. In addition, at least 0.5%
The introduction of Y ₂ O ₃ can also improve the thermal stability of the glass. Thus, by introducing a small amount of Y ₂ O ₃ , the properties and productivity of the glass can be remarkably improved. However, since Y ₂ O ₃ also has the function of suppressing the nucleation of the above glass main crystal, if the introduction amount of Y ₂ O ₃ becomes too large, the glass undergoes surface crystallization during heat treatment, and the target There is a tendency that it is difficult to obtain crystallized glass having surface smoothness. Therefore, the content of Y ₂ O ₃ is set to 8% or less. The lower limit of the content of Y ₂ O ₃ is preferably 0.5%, more preferably 1%. The upper limit of the content of Y ₂ O ₃ is
Preferably it is 5%, more preferably 3%.

TiO_TwoAnd ZrO_TwoIs β-stone as a nucleating agent
Indispensable for precipitation of crystal particles such as British solid solution and enstatite
It is a component that does not_TwoWhen the content of
It is also a component that gives the lath thermal stability. TiO_TwoAnd Zr
O_TwoIf the total content of is less than 4.5%,
Does not work well, causing glass crystallization.
However, it becomes difficult to produce a homogeneous crystallized glass. Therefore,
TiO_TwoAnd ZrO_TwoTotal content is 4.5% or more. But T
iO_TwoAnd ZrO_TwoIf the total content of
The viscosity is too low and the phases are separated or devitrified
Therefore, the productivity of glass tends to be extremely deteriorated.
You. Therefore, TiO_TwoAnd ZrO_TwoThe total content of
You. Glass productivity, chemical durability, high temperature viscosity, crystal nucleation
Considering the composition, TiO_TwoAnd ZrO_TwoOf the total content of
The lower limit is 4.5% and the upper limit is 18%. TiO _TwoAnd ZrO_TwoIf
The lower limit of the total content is preferably 5%, and the upper limit is preferably
Or 15%. However, high-temperature melting property of glass and thermal
Considering stability, ZrO_TwoContent of 0 to 10 mol%
Range and then TiO_TwoContent is in the range of 0 to 12 mol%
Is appropriate.

The crystallized glass 4 contains β-quartz solid solution and / or enstatite as a main crystal phase. crystal phase of β- quartz solid _{solution, 2MgO · 2Al 2 O 3 ·} 5SiO 2, M
_{gO · Al 2 O 3 · 3SiO} 2, and has one or more compositions selected from the group consisting of _{MgO · Al 2 O 3 · 4SiO} 2 is metastable quartz (quartz solid solution). Further, the crystal phase of enstatite can be, for example, a clinoenstatite crystal phase having a composition of Mg ₂ Si ₂ O ₆ .

The crystal grain size of the above crystals contained in the crystallized glass 4 is such that the crystallized glass of the present invention has a surface roughness Ra of 0.1.
It is preferable that the polishing surface can be formed so as to be in the range of −1.0 nm, more preferably the crystal particle diameter of the crystal phase, the surface roughness Ra is such that the surface roughness Ra is in the range of 0.1-0.5 nm. Can be formed. When the crystal particle diameter of the crystal phase contained in the crystallized glass falls within the above range, an information recording disk having excellent surface smoothness can be provided.

Li_TwoO, Na_TwoOK_TwoOxidation of alkali metals such as O
The substance lowers the liquidus temperature of the glass and precipitates crystal particles more finely.
It is a component that is added in order to take out. For example, about 2%
Li _TwoO for MgO-Al_TwoO_Three−SiO_Two-TiO_TwoWhen introduced into glass,
While the Young's modulus of glass hardly changes, the crystal
Particle size is Li_TwoAbout half or less compared to glass without O
Below. Also, Li_TwoO, Na_TwoOK_TwoO is the liquidus temperature of the glass
Also plays a major role in reducing
By introduction, the liquidus temperature of glass can be reduced by about 50 ° C.
You. But Li_TwoContent of alkaline components such as O is too large
Then, the Young's modulus of the glass decreases and the tendency to devitrify increases
For example, there is a tendency that productivity of glass is remarkably deteriorated.
Therefore, Li_TwoO, Na_TwoO and K_TwoThe total amount of O introduced is 5% or less
And Li_TwoO, Na_TwoO and K_TwoO total introduction is more favorable
Or less than 4%.

The alkaline earth metal oxide components such as CaO, SrO, BaO, ZnO and NiO mainly adjust the high temperature viscosity of the glass,
It is a component that can suppress the tendency to devitrify and homogenize crystal grains. By adding at least one of these components to the glass, the Young's modulus of the glass is slightly reduced,
Other properties of the glass can be improved, such as increasing the productivity of the glass and homogenizing the size of the crystallized particles. Young's modulus of glass, productivity, surface smoothness of crystallized glass,
Considering properties such as strength, the content of CaO is in the range of 0-10%, the content of SrO is in the range of 0-10%, and the content of BaO is 0-10%.
%, The content of ZnO is in the range of 0-10%, the content of NiO is in the range of 0-10%, and the content of CaO + SrO + BaO + ZnO + NiO is 10 mol% or less. Is preferred. In addition, Ca
The contents of O, SrO, BaO, ZnO, NiO and CaO + SrO + BaO + ZnO + NiO are all preferably 8% or less.

In addition to the above components, the crystallized glass 4 contains B ₂ O ₃ , P ₂ O ₅ , Nb ₂ O ₅ , and Ta as long as desired properties are not impaired.
Rare earth metal oxide components such as ₂ O ₅ and La ₂ O ₃ can be contained. However, these components significantly reduce the Young's modulus of the glass. Therefore, the content of B ₂ O ₃ is in the range of 0-5%, the content of P ₂ O ₅ is in the range of 0-5%, and the content of R ₂ O ₃ is 0%.
-5% (where R is a rare earth metal ion (eg, Nd
³⁺ , Pr ³⁺ , Pm ³⁺ , Sm ³⁺ , Eu ³⁺ , Gd ³⁺ , Tb ³⁺ , Dy ³⁺ , H
o ³⁺ , Er ³⁺ , Tm ³⁺ , Yb ³⁺ )), and the content of CeO ₂ is 0-5.
% And the content of N ₂ O ₅ is in the range of 0-5% (where N is Nb
Or Ta)), and B ₂ O ₃ + P ₂ O ₅ + R ₂ O ₃ + CeO ₂ + N ₂ O ₅
It is preferred that ≦ 5 mol%. Further, in consideration of the productivity of glass, the content of each of the above components and the total content are more preferably 4% or less.

As ₂ O ₃ and Sb ₂ O ₃ are components added as defoaming agents in order to homogenize glass as a raw material for crystallized glass. An appropriate amount of As ₂ O according to the high temperature viscosity of each glass
_By adding one or both of ₃ and Sb ₂ O ₃ to the glass,
A more homogeneous glass is obtained. However, when the amount of the defoamer added is too large, the specific gravity of the glass tends to increase and the Young's modulus tends to decrease, and the glass may react with the melting platinum crucible and damage the crucible. Therefore, the content of As ₂ O ₃ is in the range of 0 to ₂ %, and the content of Sb ₂ O ₃ is 0%.
It is preferred that the content be in the range of −2% and that As ₂ O ₃ + Sb ₂ O ₃ ≦ 2 mol%. In particular, the content of each of As ₂ O ₃ , Sb ₂ O ₃ and As ₂ O ₃ + Sb ₂ O ₃ is preferably 1.5% or less.

[Crystalized Glass 5] As crystallized glass, SiO ₂ : 35-65 mol%, Al ₂ O ₃ : 5-25 mol%, MgO:
It is preferable that the crystallized glass 5 has a composition containing 10 to 40 mol%, TiO ₂ : 5 to 15 mol%, and Y ₂ O ₃ : 0.8 to 10 mol%. In crystallized glass 5
SiO ₂ is a formation of a glass network structure, and the main precipitated crystals are 2MgO ・ 2Al ₂ O ₃・ 5SiO ₂ , MgO ・ Al ₂ O ₃・ 3SiO ₂ and MgO ・ Al
₂ O ₃ · metastable quartz solid solution as 4SiO _2, enstatite and (Mg · Al having a composition of MgO · SiO ₂ ) Enstatite solid solution having the composition of SiO ₃ is also a constituent component. If the content of SiO ₂ is less than 35%, the melted glass is very unstable, so that high-temperature molding may not be possible, and the above crystals may be difficult to precipitate. If the content of SiO ₂ is less than 35%, the chemical durability of the remaining glass matrix phase tends to deteriorate, and the heat resistance tends to deteriorate. On the other hand, when the content of SiO ₂ exceeds 65%, a metastable quartz solid solution and enstatite are less likely to be precipitated as a main crystal phase, and the Young's modulus of the glass tends to rapidly decrease.
Therefore, the content of SiO ₂ is in the range of 35 to 65% in consideration of the type of precipitated crystal and the amount of the precipitated crystal, chemical durability, heat resistance, and molding / productivity. From the viewpoint that crystallized glass having more preferable physical properties can be obtained, the content of SiO ₂ is preferably in the range of 37 to 60%.

Al ₂ O ₃ is an intermediate oxide of glass, and is mainly composed of 2MgO.2Al ₂ O ₃ .5SiO ₂ , MgO.Al ₂ O ₃ .3SiO ₂ , and MgO.Al ₂ O _3. 4SiO metastable constituents of quartz solid solution crystals _2. The introduction of Al ₂ O ₃ promotes the precipitation of metastable quartz solid solution crystals and contributes to the improvement of the glass surface hardness. However, when the content of Al ₂ O ₃ is less than 5%, it is difficult to precipitate crystals having a high Young's modulus as described above, the chemical durability of the glass matrix phase is reduced, and it is difficult to obtain the strength required for the substrate material. Tend to be. On the other hand, when the content of Al ₂ O ₃ exceeds 25 mol%, a high Young's modulus crystal phase such as enstatite is not easily precipitated, and the melting temperature becomes high, so that the glass becomes difficult to melt and devitrification occurs. It tends to be difficult to mold easily. Therefore, considering the melting property of glass, high-temperature moldability, and seeds of precipitated crystals, Al ₂ O
The content of ₃ is suitably in the range of 5-25%, preferably in the range of 7-22%. MgO is a modifying component of glass, and has a crystal structure of enstatite crystal and metastable quartz solid solution, 2MgO ・ 2Al ₂ O ₃・ 5SiO ₂ , MgO ・ Al ₂ O ₃・ 3SiO ₂ , and
It is also the main component of a crystal seed having a composition such as MgO.Al ₂ O ₃ .4SiO ₂ . If the content of MgO is less than 10%, the above crystals are unlikely to precipitate, the devitrification tendency and the melting temperature of the glass are high, and the working temperature range of the glass forming tends to be narrow. On the other hand, when the content of MgO exceeds 40 mol%, the high-temperature viscosity of the glass sharply decreases and becomes thermally unstable, so that productivity tends to deteriorate, and Young's modulus and durability tend to decrease. Therefore, the content of MgO is suitably in the range of 10-40%, preferably in the range of 12-38%, in consideration of productivity, chemical durability, high-temperature viscosity and strength of glass. is there.

TiO_TwoIs enstatite crystal phase or metastable stone
2MgO ・ 2Al with crystal structure of British solid solution _TwoO_Three・ 5SiO_Two, MgO ・ Al_Two
O_Three・ 3SiO_Two, And MgO ・ Al_TwoO_Three・ 4SiO_TwoNucleating agent for crystal phase precipitation
It is. In addition, TiO_TwoIs SiO_TwoWhen the content of is low
In addition, it also has the effect of suppressing the devitrification of glass. However, TiO_Twoof
When the content is less than 5%, the effect as a nucleating agent of the main crystal
Was not sufficiently obtained, and the glass was crystallized on the surface.
It tends to be difficult to produce high quality crystallized glass. one
One, TiO_TwoIf the content exceeds 15%, the high-temperature viscosity of the glass
Is too low, causing phase separation or devitrification.
Lass productivity tends to be extremely poor. for that reason,
Glass productivity, chemical durability, high temperature viscosity, crystal nucleation
Considering_TwoContent should be in the range of 5-15%.
And preferably in the range of 5.5-14%.
You.

In the crystallized glass 5, Y ₂ O ₃ plays an important role. For example, by introducing 2% of Y ₂ O ₃ , the Young's modulus of the crystallized glass can be increased by about 10 Gpa, and the liquidus temperature can be reduced by about 50-100 ° C. That is, the characteristics and productivity of the glass can be remarkably improved by introducing a small amount of Y ₂ O ₃ . However, the content of Y ₂ O ₃ is 0.8%
If it is less than this, the effect of such Y ₂ O ₃ cannot be sufficiently obtained. Further, Y ₂ O ₃ has a power to suppress the growth of the main crystal contained in the above-mentioned glass. Therefore, if the content of Y ₂ O ₃ is too large, the surface crystallization tends to occur in the heat treatment performed for the purpose of crystallizing the glass, and the target crystallized glass tends not to be produced. From such a viewpoint, the content of Y ₂ O ₃ is suitably set to 10% or less. In particular, Y ₂ O
The content of ₃ is preferably 8% or less.

[0094] Components other than the above include those of crystallized glass.
As long as the desired properties are not impaired, Li _TwoO, Na_TwoOK_TwoO, Ca
Alkali metals and alkalis such as O, SrO, BaO, ZnO, NiO
One or two or more of the oxide components of the earth metal
%, B_TwoO_Three, P_TwoO_Five, R_TwoO_Three(R: Rare earth metal excluding Y
ON), ZrO_Two, CeO_Two, N_TwoO_Five(N: Nb, Ta) 0-5 mol%
It can be contained. Also, try to homogenize the glass
As a defoamer for_TwoO_ThreeAnd / or Sb_TwoO_ThreeTo contain
You can also. High temperature viscosity changes with glass composition
Appropriate amount of As_TwoO_ThreeAnd Sb_TwoO_ThreeOr As_TwoO_Three+ Sb_TwoO_ThreeTo
By adding to glass, more homogeneous glass can be obtained
You. However, if the amount of the defoamer is too large, the specific gravity of the glass
Tends to increase and decrease the Young's modulus,
Reacts with the platinum crucible and damages the crucible
There is also. Therefore, the addition amount of the defoaming agent is preferably 2% or less.
Is suitably 1.5% or less. The above basic components
In addition, impurities in the raw material, for example, C, which becomes a fining agent for glass
l, F, SO_ThreeThis may impair the properties of the crystallized glass of the present invention.
It can be contained if it is 1% or less respectively.
it can.

The main crystal phases in the crystallized glass 5 are, for example, MgO.SiO ₂ and (Mg.Al ) An enstatite (including enstatite solid solution) crystal phase having a composition of SiO ₃ , or
2MgO ・ 2Al ₂ O ₃・ 5SiO ₂ , MgO ・ Al ₂ O ₃・ 3SiO ₂ , and MgO ・ Al ₂ O ₃・
Having one or more compositions selected from the group consisting of 4SiO ₂ may be is a metastable quartz (quartz solid solution). As the quartz solid solution, β-quartz solid solution can be particularly mentioned. Further, enstatite includes clinoenstatite, protoenstatite and enstatite. In addition to the above crystals, spinel,
Mullite, it is also possible to include a _{2MgO · SiO 2, MgO · SiO} 2 and other crystal. Further, the grain size of the crystals contained in the crystallized glass 5 is preferably 1 μm or less, and 0.5 μm
It is more preferred that: Crystal particle size is 1μ
If it exceeds m, not only may the mechanical strength of the glass be reduced, but also crystals may be lost during polishing, resulting in an increase in glass surface defects.

[Crystallized Glass 6] As the crystallized glass, SiO ₂ : 35-65 mol%, Al ₂ O ₃ : 5-25 mol%, MgO:
10-40 mol%, TiO _2: 5-15 mol%, Li ₂ O: contains 0.2 to 10 mol%, the predominant crystal phase is enstatite and metastable quartz solid solution, and the average particle size of the crystal grains Is preferably 1 μm or less. In the crystallized glass 6, SiO ₂ is the formation of a network structure of the glass, the main deposited crystals _{2MgO · 2Al 2 O 3 · 5SiO} 2, MgO · Al 2 O 3 · 3SiO 2, and MgO · Al ₂ quasi-stable quartz solid solution and MgO, such as O ₃ · 4SiO ₂
Enstatite having a composition of SiO ₂ and (MgAl ) SiO ₃
It is also a component of the enstatite solid solution having the following composition. If the content of SiO ₂ is less than 35%, the melted glass is very unstable, so that high-temperature molding may not be possible, and the above crystals may be difficult to precipitate. Also, Si
If the O ₂ content is less than 35%, the chemical durability of the remaining glass matrix phase tends to deteriorate, and the heat resistance tends to deteriorate. On the other hand, when the content of SiO ₂ exceeds 65%, a metastable quartz solid solution or enstatite is unlikely to be precipitated as a main crystal phase, and the Young's modulus of the glass tends to rapidly decrease. Therefore, the content of SiO ₂ is in the range of 35 to 65% in consideration of the type of precipitated crystal and the amount of the precipitated crystal, chemical durability, heat resistance, and molding / productivity. From the viewpoint that crystallized glass having more preferable physical properties can be obtained, the content of SiO ₂ is preferably in the range of 37 to 60%.

Al ₂ O ₃ is an intermediate oxide of glass and is a main crystal seed: 2MgO.2Al ₂ O ₃ .5SiO ₂ , MgO.Al ₂ O ₃ .3SiO ₂ ,
And metastable quartz solid solution crystals such as MgO.Al ₂ O ₃ .4SiO ₂ . The introduction of Al ₂ O ₃ promotes the precipitation of metastable quartz solid solution crystals and contributes to the improvement of the glass surface hardness. However, when the content of Al ₂ O ₃ is less than 5%, it is difficult to precipitate crystals having a high Young's modulus as described above, the chemical durability of the glass matrix phase is reduced, and it is difficult to obtain the strength required for the substrate material. Tend to be. On the other hand, when the content of Al ₂ O ₃ is 25
If it exceeds mol%, precipitation of enstatite as a main crystal phase becomes difficult, and the melting temperature becomes high, so that the glass becomes difficult to melt. Therefore, considering the solubility of glass, high-temperature moldability, crystal seeds, etc., Al ₂ O ₃
Is suitably in the range of 5-25%, preferably in the range of 7-22%.

MgO is a glass modifying component, and MgO · SiO_Two
Enstatite and (MgAl ) SiO_ThreeComposition of
Crystals of enstatite solid solution and metastable quartz solid
Has the crystal structure of the solution, 2MgO.2Al_TwoO_Three・ 5SiO_Two, MgO ・ Al_TwoO_Three
・ 3SiO_Two, And MgO ・ Al_TwoO_Three・ 4SiO _TwoHaving a composition like
It is also the main component of the crystal seed. Above if MgO content is less than 10%
It is difficult to precipitate such crystals as described above,
High melting temperature and narrow working temperature range for glass forming
Tend to On the other hand, the content of MgO exceeds 40 mol%
And the high-temperature viscosity of the glass drops sharply, causing thermal instability
, The productivity also worsens, and the Young's modulus and durability decrease.
Tend. So, the content of MgO, the production of glass
Considering properties, chemical durability, high temperature viscosity and strength,
In the range of 10-40%, preferably in the range of 12-37%
It is appropriate that

However, it is preferable to adjust the contents of MgO and Al ₂ O ₃ so that the molar ratio (Al ₂ O ₃ / MgO) is less than 0.9. When the molar ratio (Al ₂ O ₃ / MgO) is 0.9 or more, the Young's modulus of the crystallized glass tends to decrease. By setting Al ₂ O ₃ /MgO<0.9, a crystallized glass having a high Young's modulus of 150 GPa or more can be obtained. Preferably Al ₂ O ₃ /MgO<0.5, more preferably Al
₂ O ₃ /MgO<0.45. However, too small a molar ratio of Al ₂ O ₃ / MgO, since the high temperature viscosity of the glass tends to decrease Al ₂ O ₃ / MgO ratio is 0.2 or more, preferably 0.
Suitably, it is at least 25.

TiO ₂ is composed of enstatite having a composition of MgO · SiO ₂ and (Mg · Al 2 ) Crystals of enstatite solid solution having a composition of SiO _3, or metastable 2MgO · 2Al having a crystal structure of quartz solid solution _{2 O 3 · 5SiO 2, MgO} · Al 2 O 3 · 3SiO 2, and MgO · Al
It is a nucleating agent for the precipitation of ₂ O ₃ · 4SiO ₂ crystal phase. In addition, TiO ₂
Has an effect of suppressing the devitrification of glass when the content of SiO ₂ is small. However, when the content of TiO ₂ is less than 5%,
The effect of the main crystal as a nucleating agent cannot be sufficiently obtained, and the glass is crystallized on the surface, which tends to make it difficult to produce a homogeneous crystallized glass. On the other hand, when the content of TiO ₂ exceeds 15%, the high-temperature viscosity of the glass becomes too low, causing phase separation or devitrification, so that the productivity of the glass tends to be extremely deteriorated. Therefore, considering the productivity of glass, chemical durability, high-temperature viscosity, crystal nucleation and the like, the content of TiO ₂ is in the range of 5 to 15%, preferably 5.5 to 14%.
Is suitably within the range.

In the crystallized glass 6, Li_TwoO is an essential ingredient
It is. Li_TwoO lowers the liquidus temperature of the glass,
It is a component that promotes precipitation of crystal grains. For example, about 2%
Li _TwoO for MgO-Al_TwoO_Three−SiO_Two-TiO_TwoWhen introduced into glass,
While the Young's modulus of glass hardly changes, the crystal
Particle size is Li_TwoAbout half or less compared to glass without O
Below. Also, Li_TwoO plays a role in lowering the liquidus temperature of glass
Large, about 2% Li _TwoReduce the liquidus temperature of the glass by introducing O
Can be reduced by about 50 ° C. But Li_TwoO content included
If the content is too large, the high-temperature phase separation of the glass
Glass production,
Tends to significantly deteriorate the properties. So Li_TwoO content
Suitably the amount is in the range of 0.2-10%. More preferred
Or Li_TwoO content is in the range of 0.5-8%.

In the crystallized glass 6, Y ₂ O ₃ is not an essential component. For example, by introducing 2% of Y ₂ O ₃ , the Young's modulus of the crystallized glass can be increased by about 10 GPa, and The temperature can be reduced by about 50-100 ° C. That is, by introducing a small amount of Y ₂ O ₃ , the properties and productivity of the glass can be remarkably improved, and when the content of Y ₂ O ₃ is 0.8% or more, the effect of Y ₂ O ₃ can be obtained. . However, Y ₂ O ₃ has the power to suppress the growth of the main crystal contained in the above-mentioned glass. Therefore, if the content of Y ₂ O ₃ is too large, the surface crystallization tends to occur in the heat treatment performed for the purpose of crystallizing the glass, and the target crystallized glass tends not to be produced. From such a viewpoint, the content of Y ₂ O ₃ is suitably set to 10% or less. In particular, the content of Y ₂ O ₃ is preferably 8% or less.

As components other than the above, in the crystallized glass 6, as optional components, Na ₂ O: 0-10 mol%, K ₂ O: 0-10
Mol%, CaO: 0-10 mol%, SrO: 0-10 mol%, BaO: 0
-10 mol%, ZnO: 0-10 mol%, NiO: 0-10 mol%, R ₂
O ₃ : 0-5 mol% (R: B ion, rare earth metal ion), C
eO _2: 0-5 mol%, ZrO _2: 0-5 mol%, N ₂ O _5: 0-5 mol% (N: P ions, Nb ions, Ta ions), As ₂ O _3: 0-2
Mol%, Sb ₂ O ₃ : 0-2 mol%.

By containing alkali and alkaline earth metal oxide components such as Na ₂ O, K ₂ O, CaO, SrO, BaO, ZnO, and NiO, the viscosity at high temperature of the glass is mainly adjusted to reduce the tendency to devitrify. And crystal grains can be homogenized. For example, when the above components are introduced into the crystallized glass 6 of the present invention by about 2 to 5%, the Young's modulus is slightly reduced, but the productivity of the glass is improved, and the particle size of the crystallized particles is homogenized. Other properties of the glass can be improved. However, considering the properties of glass such as Young's modulus, productivity, surface smoothness and strength of crystallized glass, Na ₂ O, K ₂ O, CaO, SrO, Ba
The content of alkali and alkaline earth metal oxide components such as O, ZnO and NiO is preferably 10% or less, more preferably 7% or less.

By including B ₂ O ₃ and P ₂ O ₅ in the crystallized glass 6, devitrification mainly in the glass forming temperature range can be suppressed. However, since these components significantly lower the Young's modulus of the glass, the content is desirably 5% or less. Further, considering the productivity of glass, the content is more preferably 4% or less.

By making the crystallized glass 6 contain R ₂ O ₃ (R: rare earth metal ion), CeO ₂ , and N ₂ O ₅ (N: Nb, Ta), the thermal stability and productivity of the glass can be improved. And the Young's modulus can be improved. Further, since these components also have a function of suppressing the growth of crystal grains, they are components that enable the production of glass having more excellent surface smoothness. However, all of these oxides are expensive and
If the amount is too large, the liquidus temperature of the glass is deteriorated or the specific gravity of the glass is sharply increased. Therefore, it is appropriate that the content is 5% or less. R ₂ O
The introduction amount of ₃ is appropriately 5% or less, preferably 4% or less in consideration of the productivity of glass, specific gravity, liquidus temperature and the like.

The crystallized glass 6 may contain As ₂ O ₃ and / or Sb ₂ O ₃ as a defoaming agent in order to homogenize the glass. Depending on the high temperature viscosity, which changes depending on the glass composition, an appropriate amount of As ₂ O ₃ , Sb ₂ O ₃ or As ₂ O ₃ + Sb ₂ O ₃
Is added to the glass to obtain a more homogeneous glass. However, if the amount of the defoaming agent is too large, the specific gravity of the glass tends to increase and the Young's modulus tends to decrease, and may react with the platinum crucible for melting to damage the crucible. Therefore, it is appropriate that the addition amount of the defoaming agent is 2% or less, preferably 1.5% or less. In addition to the above basic components, impurities in the raw material, for example, C which becomes a fining agent for glass
l, F, SO _{3 and the} like can be contained as long as they are 1% or less, respectively, without impairing the properties of the crystallized glass 6.

The main crystal phase in the crystallized glass 6 is, for example,
For example, MgO ・ SiO_TwoAnd (MgAl ) SiO_ThreeHaving the composition of
Tight (including enstatite solid solution) and 2MgO · 2
Al_TwoO _Three・ 5SiO_Two, MgO ・ Al_TwoO_Three・ 3SiO_Two, And MgO ・ Al_TwoO_Three・ 4SiO_Two
Having one or more compositions selected from the group consisting of
It is a metastable quartz (quartz solid solution). Quartz solid solution
Particularly, a β-quartz solid solution can be mentioned.
In addition, enstatite includes clinoenstatite,
Lotoenstatite and enstatite are included.
Crystallized glass 6 consists of enstatite and metastable quartz solids.
Excellent Young by containing solution as main crystal phase
Rate, strength and heat resistance. However,
Crystal, spinel, mullite, 2MgO ・ SiO_Two, MgO ・ Si
O_Two, Titanates, and other crystals.

The average particle size of crystals such as enstatite and metastable quartz solid solution contained in the crystallized glass 6 is 1 μm.
It is as follows. When the crystal particle diameter is 1 μm or less, a crystallized glass having excellent strength and surface smoothness can be obtained. When the uniform particle diameter of the crystal exceeds 1 μm, not only the mechanical strength of the glass is reduced, but also the crystal is lost during polishing to deteriorate the surface roughness of the glass. The particle size of the crystal particles is preferably 0.5 μm or less.

[Crystalized Glass 7] As crystallized glass, SiO ₂ : 35-65 mol%, Al ₂ O ₃ : 5-25 mol%, MgO:
Crystallized glass 7 having a composition containing 10-40 mol% and TiO ₂ : 5-15 mol% and having a molar ratio (Al ₂ O ₃ / MgO) of less than 0.5 is preferred. SiO ₂ in the crystallized glass 7 is forms the network structure of the glass, the main deposited crystals _{2MgO · 2Al 2 O 3 · 5SiO} 2, MgO · Al 2 O 3 · 3SiO 2, and MgO · Al ₂ O quasi-stable quartz solid solution and MgO, such as the ₃ · 4SiO ₂
Enstatite having a composition of SiO ₂ and (MgAl ) SiO ₃
It is also a component of the enstatite solid solution having the following composition. If the content of SiO ₂ is less than 35%, the melted glass is very unstable, so that high-temperature molding may not be possible, and the above crystals may be difficult to precipitate. Also, Si
If the O ₂ content is less than 35%, the chemical durability of the remaining glass matrix phase tends to deteriorate, and the heat resistance tends to deteriorate. On the other hand, when the content of SiO ₂ exceeds 65%, a metastable quartz solid solution or enstatite is unlikely to be precipitated as a main crystal phase, and the Young's modulus of the glass tends to rapidly decrease. Therefore, the content of SiO ₂ is in the range of 35 to 65% in consideration of the type of precipitated crystal and the amount of the precipitated crystal, chemical durability, heat resistance, and molding / productivity. From the viewpoint that a crystallized glass having more preferable physical properties can be obtained, the content of SiO ₂ is preferably in the range of 40 to 60%.

Al ₂ O ₃ is an intermediate oxide of glass and is a main crystal seed: 2MgO.2Al ₂ O ₃ .5SiO ₂ , MgO.Al ₂ O ₃ .3SiO ₂ ,
And metastable quartz solid solution crystals such as MgO.Al ₂ O ₃ .4SiO ₂ . The introduction of Al ₂ O ₃ promotes the precipitation of metastable quartz solid solution crystals and contributes to the improvement of the glass surface hardness. However, when the content of Al ₂ O ₃ is less than 5%, it is difficult to precipitate crystals having a high Young's modulus as described above, the chemical durability of the glass matrix phase is reduced, and it is difficult to obtain the strength required for the substrate material. Tend to be. On the other hand, when the content of Al ₂ O ₃ is 25
If it exceeds mol%, precipitation of enstatite as a main crystal phase becomes difficult, and the melting temperature becomes high, so that the glass becomes difficult to melt. Therefore, considering the solubility of glass, high-temperature moldability, crystal seeds, etc., Al ₂ O ₃
Is suitably in the range of 5-25%, preferably in the range of 7-22%.

MgO is a glass modifying component, and MgO · SiO_Two
Enstatite and (MgAl ) SiO_ThreeComposition of
Crystals of enstatite solid solution and metastable quartz solid
Has the crystal structure of the solution, 2MgO.2Al_TwoO_Three・ 5SiO_Two, MgO ・ Al_TwoO_Three
・ 3SiO_Two, And MgO ・ Al_TwoO_Three・ 4SiO _TwoHaving a composition like
It is also the main component of the crystal seed. Above if MgO content is less than 10%
It is difficult to precipitate such crystals as described above,
High melting temperature and narrow working temperature range for glass forming
Tend to On the other hand, the content of MgO exceeds 40 mol%
And the high-temperature viscosity of the glass drops sharply, causing thermal instability
, The productivity also worsens, and the Young's modulus and durability decrease.
Tend. So, the content of MgO, the production of glass
Considering properties, chemical durability, high temperature viscosity and strength,
In the range of 10-40%, preferably in the range of 12-38%
It is appropriate that

However, the contents of MgO and Al ₂ O ₃ are adjusted so that the molar ratio (Al ₂ O ₃ / MgO) is less than 0.5. This is because when the molar ratio (Al ₂ O ₃ / MgO) is 0.5 or more, the Young's modulus of the crystallized glass tends to sharply decrease.
By setting Al ₂ O ₃ /MgO<0.5, a crystallized glass having a high Young's modulus of 150 GPa or more can be obtained. Preferably, Al ₂ O ₃ /MgO<0.45. However, Al ₂ O ₃ / M
If the molar ratio of gO is too small, the high temperature viscosity of the glass tends to decrease. Therefore, the Al ₂ O ₃ / MgO ratio is suitably 0.2 or more, preferably 0.25 or more.

TiO ₂ is composed of enstatite having a composition of MgO · SiO ₂ and (Mg · Al 2 _{) 2MgO · 2Al 2 O 3 ·} 5SiO 2, MgO · Al 2 O 3 · 3SiO 2 having a crystal or metastable quartz crystal structure of the solid solution of enstatite solid solution having a composition of SiO _3, and MgO · Al ₂ O
₃ · 4SiO ₂ is a nucleating agent of crystal phase precipitation. In addition, TiO
_2, when the content of SiO ₂ is small, also it has an effect of suppressing the devitrification of the glass. However, if the content of TiO ₂ is less than 5%, the effect as a nucleating agent of the main crystal is not sufficiently obtained,
The glass is crystallized on the surface, and it tends to be difficult to produce a homogeneous crystallized glass. On the other hand, when the content of TiO2 is 15
%, The high-temperature viscosity of the glass becomes too low, causing phase separation or devitrification, so that the productivity of the glass tends to be extremely deteriorated. Therefore, considering the productivity of glass, chemical durability, high temperature viscosity, crystal nucleation, etc., TiO ₂
Is in the range of 5-15%, preferably 5.5-1.
Suitably, it is in the range of 4%.

In the crystallized glass 7, Y ₂ O ₃ is not an essential component, but, for example, by introducing 2% of Y ₂ O ₃ , the Young's modulus of the crystallized glass can be increased by about 10 GPa and the liquid phase The temperature can be reduced by about 50-100 ° C. That is, by introducing a small amount of Y ₂ O ₃ , the properties and productivity of the glass can be remarkably improved, and when the content of Y ₂ O ₃ is 0.8% or more, the effect of Y ₂ O ₃ can be obtained. . However, Y ₂ O ₃ has the power to suppress the growth of the main crystal contained in the above-mentioned glass. Therefore, if the content of Y ₂ O ₃ is too large, the surface crystallization tends to occur in the heat treatment performed for the purpose of crystallizing the glass, and the target crystallized glass tends not to be produced. From such a viewpoint, the content of Y ₂ O ₃ is suitably set to 10% or less. In particular, the content of Y ₂ O ₃ is preferably 8% or less.

[0116] Components other than the above include those of crystallized glass.
As long as the desired properties are not impaired, Li _TwoO, Na_TwoOK_TwoO, Ca
Alkali metals and alkalis such as O, SrO, BaO, ZnO, NiO
One or two or more of the oxide components of the earth metal
%, B_TwoO_Three, P_TwoO_Five, R_TwoO_Three(R: Rare earth metal excluding Y
ON), ZrO_Two, CeO_Two, N_TwoO_Five(N: Nb, Ta) 0-5 mol%
It can be contained. Also, try to homogenize the glass
As a defoamer for_TwoO_ThreeAnd / or Sb_TwoO_ThreeTo contain
You can also. High temperature viscosity changes with glass composition
Appropriate amount of As_TwoO_ThreeAnd Sb_TwoO_ThreeOr As_TwoO_Three+ Sb_TwoO_ThreeTo
By adding to glass, more homogeneous glass can be obtained
You. However, if the amount of the defoamer is too large, the specific gravity of the glass
Tends to increase and decrease the Young's modulus,
When reacting with a platinum crucible and damaging the crucible
There is also. Therefore, the addition amount of the defoaming agent is preferably 2% or less.
Is suitably 1.5% or less. The above basic components
In addition, impurities in the raw material, for example, C, which becomes a fining agent for glass
l, F, SO_ThreeThis may impair the properties of the crystallized glass of the present invention.
It can be contained if it is 1% or less respectively.
it can.

The main crystal phase in the crystallized glass 7 is, for example,
For example, MgO ・ SiO_TwoAnd (MgAl ) SiO_ThreeHaving the composition of
Tight (including enstatite solid solution) and 2MgO · 2
Al_TwoO _Three・ 5SiO_Two, MgO ・ Al_TwoO_Three・ 3SiO_Two, And MgO ・ Al_TwoO_Three・ 4SiO_Two
Having one or more compositions selected from the group consisting of
Can be metastable quartz (quartz solid solution)
You. As the quartz solid solution, β-quartz solid solution is particularly exemplified.
I can do it. In addition, enstatite includes
Statite, protoenstatite and enstatite
Is included. In addition to the above crystals, spinel and unevenness
Site, 2MgO ・ SiO_Two, MgO ・ SiO_TwoIncluding other crystals
Can also be. Further, the crystal grains contained in the crystallized glass 7
The particle size of the particles is preferably 1 μm or less, 0.5 μm
It is more preferred that: Crystal particle size is 1μ
Exceeding m will not only reduce the mechanical strength of the glass,
Cause crystal loss during polishing,
The surface roughness may be deteriorated.

The substrate of the present invention preferably has a Young's modulus of 110 GPa or more. When the Young's modulus is 110 GPa or more, a highly rigid substrate can be obtained. Specifically, Young's modulus 110G
A substrate of Pa or more can be obtained. By using a substrate having a Young's modulus of 110 GPa or more, deformation of the medium during high-speed rotation can be reduced, and problems such as a head crash even when the flying height is reduced can be prevented. A preferred range of the Young's modulus is 110 GPa or more, and a more preferred range is 140 GPa or more. When the Young's modulus is 110 GPa or more, even if the glass substrate rotates at a high speed, the substrate is unlikely to be warped or blurred, and the substrate can be made thinner.

The substrate of the present invention has a coefficient of thermal expansion of 60 × 10 ^-7 /
It is preferable that the temperature is not lower than ° C. By setting the thermal expansion coefficient of the substrate in the above range, it becomes easy to match the thermal expansion coefficient with a metal (for example, stainless steel) mounting tool or a rotating shaft when the substrate is mounted on the drive. The thermal expansion coefficient of these crystallized glasses is as large as 90 (10 ⁻⁷ / ° C.) or more, and the compatibility with the stainless steel parts of the hard disk is improved, so that precision design required for high density is facilitated.

The composition of the crystallized portion of the crystallized glass constituting the crystallized glass substrate obtained by the production method of the present invention depends on the composition of the base glass, but is metastable with high hardness and acid resistance and a large Young's modulus. Quartz solid solution
2MgO ・ 2Al ₂ O ₃・ 5SiO ₂ , MgO ・ Al ₂ O ₃・ 3SiO ₂ and MgO ・ Al ₂
O ₃ 4SiO ₂ · enstatite MgO · SiO ₂ and a solid solution thereof is tight, MgO · A ₂ O ₃ spinel, ZnO · A1 ₂ O ₃ and solid solutions _{thereof, MgO · CaO · 2SiO 2,} CaO · Al 2 O 3・ 2SiO ₂ , BaO ・ Al ₂
It is preferably O ₃ .2SiO ₂ or the like. Since the crystallized portion is generally harder than the matrix layer and chemically stable, it becomes fine projections uniformly dispersed on the substrate surface by appropriately selecting a processing method and conditions. Since these minute projections serve as point-like contact points of the magnetic head, they have the effect of preventing the sticking phenomenon with the head caused by lubricating oil or water. It also serves to prevent damage to the magnetic film due to collision. Further, the minute projections also have a function of cleaning dirt deposited on the slider surface of the magnetic head. For this reason, the fall and collision of the magnetic head can be prevented, and the reliability life of the disk device can be drastically increased. Such fine protrusions on the glass surface have properties and effects that are higher than those of the conventionally used textured surface.

The above-mentioned microcrystals are essentially produced by changing the phase from amorphous glass to stable crystals, and the projections cause differences in the material properties such as hardness and acid resistance between the base glass part and the crystal part. It is formed using. Therefore, there is no problem of burrs, chipping, and reattachment of chips, which are problems in conventional texture processing. Furthermore, the height of the protrusions can be controlled by optimizing the particle size and density of the crystal grains by adjusting the glass composition and the heat treatment conditions. As a result, the surface of the magnetic head that has extremely excellent flying characteristics over the entire substrate can be obtained. Can be formed. In addition, since the crystal particles serve as an end point of microcracks generated in the continuous glass layer, they also have the effect of suppressing the growth and expansion of cracks. For this reason, the mechanical strength and hardness of the crystallized glass are increased, so that the glass is less likely to be broken, and has the effect of realizing sufficient mechanical strength as a magnetic disk substrate. In addition, since the crystallized glass material itself is non-magnetic, there is no need to worry about magnetization due to heating, etc., and since it is a single substrate material,
Since the number of steps is small, the manufacturing cost can be reduced. Further, since the same material is formed by vitrification through a melting process, there is no void or void which is a problem in the sintered material.

As described above, the crystallized glass has the advantage that the precipitated crystal layer and the matrix glass layer have the advantages of each other, and that the crystallized glass of the present invention has excellent physical properties due to the interaction. It is a composite material suitable as a high-performance substrate for disks.

The present invention includes a method for producing an information recording medium in which at least an information recording layer is formed on the main surface of a crystallized glass substrate obtained by the production method of the present invention. The substrate obtained by the manufacturing method of the present invention has a small deformation at the time of high-speed rotation, and the write / read head can be stably approached to a distance very close to the surface of the information recording medium. Therefore, a highly reliable medium with a high recording density can be obtained.

The information recording medium obtained by the manufacturing method of the present invention can be a magnetic recording medium. The problem of adhesion between the magnetic head and the medium surface can be prevented, and the flying height of the magnetic head can be reduced. As a result, a highly reliable magnetic recording medium with a high recording density can be obtained. [Description of Magnetic Disk] An information recording medium obtained by the manufacturing method of the present invention is characterized by having a substrate obtained by the manufacturing method of the present invention and a recording layer formed on the substrate. Hereinafter, a magnetic disk (hard disk) having at least a magnetic layer formed on a main surface of a substrate made of crystallized glass obtained by the manufacturing method of the present invention will be described. The layers other than the magnetic layer include an underlayer, a protective layer, a lubricating layer, an unevenness control layer, and the like from the functional aspect, and are formed as necessary. Various thin film forming techniques are used to form these layers. The material of the magnetic layer is not particularly limited. Examples of the magnetic layer include, in addition to Co-based, ferrite-based and iron-rare-earth-based. The magnetic layer may be any of horizontal magnetic recording and perpendicular magnetic recording. As the magnetic layer, specifically, for example, Co
Pt, CoCr, CoNi, CoNiCr, CoCrTa, CoPtCr and CoNiCrPt,
Magnetic thin films such as CoNiCrTa, CoCrPtTa, and CoCrPtSiO are exemplified. Further, the magnetic layer may be divided by a non-magnetic layer to have a multilayer structure in which noise is reduced.

The underlayer in the magnetic layer is selected according to the magnetic layer. As the underlayer, for example, Cr, Mo, Ta, T
Examples include at least one or more materials selected from nonmagnetic metals such as i, W, V, B, and Al, and an underlayer made of an oxide, nitride, carbide, or the like of those metals. In the case of a magnetic layer containing Co as a main component, from the viewpoint of improving the magnetic properties,
Preferably, it is Cr alone or a Cr alloy. The underlayer is not limited to a single layer, and may have a multilayer structure in which the same or different layers are stacked. For example, a multilayer base layer of Al / Cr / CrMo, Al / Cr / Cr, or the like can be given. Further, an unevenness control layer may be provided between the substrate and the magnetic layer or above the magnetic layer to prevent the magnetic head and the magnetic disk from being attracted to each other.
By providing the unevenness control layer, the surface roughness of the magnetic disk is appropriately adjusted, so that the magnetic head and the magnetic disk do not stick to each other, and a highly reliable magnetic disk can be obtained. There are various known materials and methods for forming the unevenness control layer, and there is no particular limitation. For example, as the material of the unevenness control layer, Al, Ag, Ti, Nb, Ta, Bi, Si, Zr,
Cr, Cu, Au, Sn, Pd, Sb, Ge, at least one or more metals selected from Mg, or alloys thereof, or
An underlayer made of such oxides, nitrides, carbides, and the like can be given. From the viewpoint of easy formation, it is desirable to use a metal containing Al as a main component, such as Al alone, an Al alloy, Al oxide, or Al nitride.

In consideration of head stiction, the surface roughness of the unevenness forming layer is preferably Rmax = 5 to 30 nm. A more preferred range is Rmax = 10
20 nm. When Rmax is less than 5 nm, the surface of the magnetic disk is almost flat, so that the magnetic head and the magnetic disk are attracted, the magnetic head and the magnetic disk are attracted, and the magnetic head and the magnetic disk are damaged, or the head crashes due to the attracting. It is not preferable because it causes it. Also, Rmax
Is more than 30 nm, the glide height (glide height) is increased, and the recording density is undesirably reduced. Note that, without providing the unevenness control layer, the surface of the glass substrate may be subjected to texturing by providing an unevenness by means of etching treatment, laser light irradiation, or the like.

Examples of the protective layer include a Cr film, a Cr alloy film, a carbon film, a zirconia film and a silica film.
These protective films can be continuously formed with an underlayer, a magnetic layer, and the like by an in-line type sputtering apparatus or the like. Further, these protective films may have a single-layer structure or a multi-layer structure composed of the same or different films. Another protective layer may be formed on the protective layer or in place of the protective film. For example, colloidal silica fine particles may be dispersed and applied while diluting tetraalkoxylan with an alcohol-based solvent on the protective layer, followed by firing to form a silicon oxide (SiO ₂ ) film. In this case, it functions as both the protective film and the unevenness control layer. Various proposals have been made for the lubricating layer, but generally, a liquid lubricant, perfluoropolyether, is diluted with a solvent such as Freon, and the medium surface is dipped, spin-coated, or sprayed. And heat-treating as necessary.

[0128]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a magnetic recording medium substrate and a magnetic recording medium will be described below. The manufacturing process of a magnetic disk substrate using crystallized glass starts from material preparation according to a predetermined composition, and then is performed by heating and melting, stirring and fining, high-temperature molding by a press method, annealing, disk shape processing, nucleation heat treatment, Basically, the nucleus growth heat treatment and the surface grinding, polishing, and cleaning are performed in this order. The manufacturing process is not limited to the above. For example, instead of surface polishing, sputter etching or chemical etching may be performed. Further, the heat treatment for crystallization can be completed in one step. Further, changing the order of the steps and the contents of the steps in accordance with the technical contents and the material characteristics is not against the gist of the present invention.

Hereinafter, typical production process procedures will be described with reference to Examples. The material used in this example is MgO-Al ₂ O _3-
A SiO ₂ -TiO ₂ based crystallized glass. The specific composition is MgO
Component 30.5 mol%, Al ₂ O ₃ component is 10.5 mole%, SiO ₂ component 4
Raw material powders such as MgO, N ₂ O ₃ , SiO ₂ , TiO ₂ , Z, so that 6 mol%, TiO ₂ component is 10.0 mol%, and ZrO ₂ component is 2.0 mol%
To weigh 300 kg of rO ₂ and improve the solubility of glass
K ₂ CO ₃ and Y ₂ to be 0.5 mol% of Y ₂ O ₃ and 0.5 mol% of K ₂ O
O ₃ was introduced and mixed well to obtain a prepared batch (composition 1).
Further, MgO component is 26.0 mole%, A1 ₂ O ₃ component is 14.0 mole%, Si
300 kg of the raw material powders MgO, Al ₂ O ₃ , SiO ₂ , TiO ₂ so that the O ₂ component is 50.0 mol% and the TiO ₂ component is 9.0 mol%
Weigh and add 1.0 mol% to improve the solubility of the glass
Y ₂ O ₃ introduced Y ₂ O ₃ so that the, was thoroughly mixed and blended batch (composition 2). Next, the prepared batch of composition 1 was placed in a platinum crush, and melted for 12 hours while stirring at 1600 ° C. in a glass melting furnace, and then the temperature of the melting furnace was lowered to 1300 ° C., and the temperature was lowered to about 10-30 at the same temperature. Hold for minutes. Thereafter, the glass melt was poured into a stainless steel mold through a platinum pipe having a diameter of 7 mm, and a disc having a diameter of 90 mm and a thickness of 2 mm was formed by a press method.

The above-prepared glass disk was ground to a thickness of 1.1 mm with diamond pellets of 200 cm fixed abrasive grains, then placed in a crystallization furnace, and heated to 770 ° C. at a rate of 10 ° C./min. After a nucleation heat treatment at a temperature of about 60 minutes, the mixture was immediately heated to 1000 ° C. at a rate of 5 ° C. every minute, and a crystallization heat treatment was performed at the same temperature for 3 hours. The heat-treated glass disk was cooled to room temperature at a rate of 5 ° C./min to obtain a crystallized glass disk. The nucleation processing temperature and time and the crystallization processing temperature and time can determine the density and particle size of the crystal grains. Therefore, the time can be changed as needed other than the conditions described in the present embodiment.
Generally, the nucleation temperature is slightly higher than the glass transition temperature Tg (for example, the temperature range from Tg to Tg + 60 ℃)
It is preferable that the temperature is lower than the softening point temperature of the glass.
If larger crystal grains are required, this can be achieved by increasing the crystallization temperature and extending the crystallization time.If smaller crystal grains are required, the crystallization temperature is lowered and the crystallization time is reduced. It can be realized by doing. The size of the crystal grains is determined according to the surface recording density of magnetic recording and the surface characteristics of the magnetic disk. Table 1 shows each property of the crystallized glass of Example 1-1 produced in the above manufacturing process.

Crystallized glass was obtained in the same manner as for composition 2, but the heat treatment was carried out under the conditions shown in the right column of Table 1 to obtain the crystallized glass of Example 2-1. Next, the crystallized glass substrate after heat treatment and cooling (both Examples 1-1 and 2-1) was ground with a fixed abrasive diamond grinder, and a fluid abrasive (eg, colloidal silica, cerium oxide, alumina) was used. Polish both sides with a grinder. The grinding machine is equipped with two upper and lower grinding plates equipped with fixed abrasives. The glass substrate to be processed is sandwiched between jigs using a jig, and the platen is rotated by rotating the platen. A double-side polishing machine also grinds a crystallized glass disk in a similar manner. The purpose of this polishing is to form fine projections on the surface of the crystallized glass. Since the glass portion in the crystallized glass has a lower hardness than the crystallized portion, it is relatively quickly polished, and as a result, fine projections can be formed on the surface of the glass. In this case, the crystallized portion naturally becomes a projection. If the surface has abnormal protrusions, the pressing force of the platen is concentrated at that point, and such abnormal protrusions are promptly removed. Therefore, by using such a processing method, it is possible to obtain a processed surface in which the heights of the protrusions in the substrate surface are uniform. Accordingly, a surface having no abnormally high projections colliding with the magnetic head and having fine and uniform projections necessary and sufficient to prevent sliding reliability and adhesion can be obtained. Of course, the surface pressure of this polishing process,
The rotation speed, time and polishing material of the surface plate are important factors that govern the shape of the fine projections on the processed surface.

[0132] It has projections higher than the polished surface,
To obtain a substrate surface with protrusions of uniform height without protrusions
For this purpose, the polished crystallized glass is further treated with silicofluoric acid (H
_TwoSiF ₆) Or silicofluoric acid (H_TwoSiF₆) And hydrofluoric acid (HF) mixed acid solution
Surface projections of the required size by etching with
You can also get. For example, Figure 1 shows 0.25% hydrofluoric acid and 0.25%
Of Example 1 etched with mixed acid of silicofluoric acid
Shows the relationship between glass surface roughness Rmax and etching time
You. The surface roughness of the crystallized glass before etching is about Rmax
5.0 nm, but etch with mixed solution of hydrofluoric acid and silicic hydrofluoric acid
Surface roughness Rmax increases with etching time
It will gradually increase to the required height of the surface protrusions
By setting the etching time, the height of the protrusions in the substrate
Well-processed surface with no abnormal protrusions with abrasive remaining
Can be obtained.

Observation of the main surfaces of the obtained substrates of Examples 1-1 and 2-1 revealed that the crystal grains had a grain size of 100 nm or less (average grain size was 20 to 30 nm). The particle size of the crystal particles was measured based on a transmission electron microscope (TEM) photograph using the substrate as a sample, and the particle size of the crystal particles was determined from the difference in density between the crystal particle portion and the glass portion. FIG. 2 shows a TEM photograph of the substrate of Example 1-1. Table 1 shows the results of measuring the areal density, crystallinity, Young's modulus, and other physical properties of crystal grains having a particle diameter of 10 nm or more and exposed on the main surface. The values of the areal density in Table 1 indicate average values when the areal densities at four arbitrary positions on the main surface of the glass substrate were measured. The area density of 4 places is 10 ⁷ pieces / mm ² ~
It was 10 ⁹ cells / mm ² range. The Young's modulus of the substrates of Examples 1-1 and 2-1 also showed a high value of 140 GPa or more, and the surface roughness (maximum height) Rmax measured by AFM was 10 nm or less.

[0134]

[Table 1]

Thereafter, about 300 ° C. in a vacuum sputtering apparatus.
After vacuum vacuuming at about the temperature, a chromium underlayer, a magnetic film layer, and a carbon protective film are sequentially formed. Finally, a lubricant made of fluorine-based hydrocarbon is applied to the surface in the atmosphere to complete the magnetic disk. When the performance (glide height test) of the magnetic disk according to the present embodiment was tested, the minimum flying distance was 10 nm. It was recognized as a substrate suitable for increasing the density of magnetic recording.

The crystallized glass of Example 3 having the composition shown in Table 1 was prepared in the same manner as in Example 1-1, and the surface density and crystallinity of crystal grains having a particle diameter of 10 nm or more exposed on the main surface were prepared. ,
Table 1 shows the results of measuring the Young's modulus and other physical properties. Note that the values of the areal density in Table 1 indicate average values obtained by measuring the areal densities at four arbitrary positions on the main surface of the glass substrate. The areal density at four locations was in the range of 10 ⁷ / mm ² to 10 ⁹ / mm ² . Examples 1-2 to 1 showing the compositions in Tables 2 and 3
-15 was prepared in the same manner as in Example 1-1, and the results of measuring the surface density, crystallinity, Young's modulus, and other physical properties of the crystal particles having a particle diameter of 10 nm or more exposed (projected) on the main surface were measured. Table 2
And 3. Similarly, Example 2-2 whose composition is shown in Tables 4 and 5
~ 2-23 were prepared in the same manner as in Example 2-1, and the surface density of crystal grains having a particle diameter of 10 nm or more exposed (projected) on the main surface,
Tables 4 and 5 show the results of measuring the crystallinity, Young's modulus, and other physical properties. These Examples 1-2 to 1-15 and Example 2-2
When the areal densities at any four locations on the main surface of the glass substrate of ~ 2-23 were measured, as shown in Tables 2-5, all 10
It was in the range of ⁷ / mm ² to 10 ⁹ / mm ² . Examples 2-2 to 2-2
In the crystallized glass of No. 3, the main crystal or the crystal containing 50% by weight or more was an α-quartz solid solution or a quartz crystal and enstatite (including the solid solution).

[0137]

[Table 2]

[0138]

[Table 3]

[0139]

[Table 4]

[0140]

[Table 5]

[0141] In the above Examples 1-3 MgO-A1 ₂ O ₃ -SiO
_{Although a 2-} TiO ₂ -based crystallized glass was used, the crystallized glass material is not limited to this, and a crystallized glass substrate for a disk suitable for the following material systems can be provided. MgO-A1 ₂ O ₃ -SiO ₂ ; Li ₂ O-MgO-A1 ₂ O ₃ -SiO ₂ ; MgO-ZnO-A1 ₂ O ₃ -SiO ₂ ; MgO-SrO-A1 ₂ O ₃ -SiO ₂ ; MgO- A1 ₂ O ₃ -SiO ₂ -ZrO ₂ ; BaO-A1 ₂ O ₃ -SiO ₂ ; CaO-A1 ₂ O ₃ -SiO ₂ ; MgO-CaO-Al ₂ O ₃ -SiO ₂ ;

The following are the crystal phases obtained from the above-mentioned material systems. MgO · SiO ₂ and a solid solution thereof (e.g., (Mg, Al) O · SiO 2); various quartz solid solution _{(MgO · A1 2 O 3 ·} 3SiO 2, 2MgO · 2Al 2 O 3 · 5S
_{iO 2, MgO · Al 2 O} 3 · 4SiO 2); MgO · Al 2 O 3 and solid solutions thereof (e.g., _{ZnO · Al 2 O 3) Li} 2 O · A1 2 O 3 · 2SiO 2 SiO 2 These crystals The phase is determined by the starting material, heat treatment conditions, and the type and content of the nucleating agent, and is precipitated in various combinations, and is not uniquely determined. Particularly preferred crystallized glasses include the above-described crystallized glasses 1 and 2.

In general, it is necessary to add a nucleating agent only for preparing crystallized glass. For example, there is a method using a metal colloid produced by a combination of gold, silver, copper and cerium.
On the other hand, oxides such as TiO ₂ , ZrO ₂ , and P ₂ O ₅ that can promote the phase separation of the glass are often used as nucleation promoters. In addition, heavy metal elements such as Nb, Ta, Mo, and W may be used. In some cases, the nucleating agent may not be added depending on the type of glass. When the starting material of the precipitated crystal phase is the same, the average density and particle size of the crystal grains are determined by the two-step heat treatment temperature and time, and the density and size of the obtained precipitated crystal phase are important factors. Also for the various crystallized glass substrates of the above Examples 1-2 to 1-15, the average value of the crystal particle diameter is in the range of 10 to 300 nm, and the particle diameter of the protruding crystal particles is 100 nm or less. And the areal density exceeds 10 ⁶ / mm ² and 10 ⁹ / mm ²
A substrate in a range suitable for an information recording medium in the following range can be obtained. In addition, the Young's modulus is as high as 140 GPa or more, and the surface roughness (maximum roughness) Rmax measured by AFM
Was 10 nm or less. Film formation was performed in the same manner as in Examples 1-1 and 2-1 to obtain a magnetic recording medium. Further, the above Examples 2-2 to 2
-23, as shown in Tables 4 and 5, the average value (average particle size) of the crystal particles is 0.5 μm (5 μm).
00 nm) and the size of the protruding crystal particles is 3
00 nm or less, and the areal density exceeds 10 ⁶ / mm ² and 10 ⁹
Substrates in a range suitable for an information recording medium substrate in a range of pieces / mm ² or less are obtained. In addition, the Young's modulus is as high as 130 GPa or more, and the surface roughness (maximum height) R measured by AFM
max was less than 30 nm. Film formation was performed in the same manner as in Examples 1-1 and 2-1 to obtain a magnetic recording medium. As a result of the glide height test of each medium of Examples 1-2 to 1-15 and 2-2 to 2-23, each result was 30 nm or less (10 nm or less for Examples 1-2 to 1-15, and 30 nm or less for Examples 2-2 to 2-23)
Low flying height can be stably realized, no occurrence of adsorption is observed, and excellent slidability is obtained.

(Comparative Examples 1-2) Next, the composition of the glass and the heat treatment conditions (heat treatment temperature and time) for crystal nucleus growth were appropriately adjusted to obtain a crystallized glass substrate having the characteristic values shown in Table 6. Was prepared. Thereafter, a film was formed in the same manner as in Examples 1-1 and 2-1 to obtain a magnetic recording medium.

[0145]

[Table 6]

In the case of the crystallized glass substrate of Comparative Example 1, the particle size
The areal density of crystal grains of 10 nm or more is 5 × 10 ⁴ to 1 × 10 ⁶ / mm
² and 10 ⁶ / mm ² or less, poor sliding characteristics with magnetic head (adsorption phenomenon, large friction coefficient), crystallinity 14%
And the Young's modulus is 90 to 100 GPa, which is smaller than that of the embodiment. Therefore, it shows a higher value than the head flying height assumed by Rmax on the surface, and both sliding reliability and low flying height (30 nm or less) I was not satisfied. On the other hand, if the crystallized glass substrate of Comparative Example 2, the surface density of the particle size 10nm or more crystal grains 2 × 10 ⁹ to 5 × 10 ¹⁰ pieces / mm ^2, and more than 10 ⁹ / mm ^2, High crystallinity of 70-80% and Young's modulus of 165-180GPa
And a high value, which was good in terms of rigidity. But,
Due to the areal density becoming too large, there are places where individual crystal grains are fused to form large crystal grains,
As a result, the surface roughness Rmax of the substrate deteriorated to 45 nm. Therefore, although the sliding characteristics with the magnetic head (adhesion phenomenon, large friction coefficient) were good, the head flying height
30 nm or less could not be satisfied.

(Examples 4 to 8, Reference Example 1) Next, Example 1-1
In the surface treatment step using an acid containing silicic acid (only silicic acid) after polishing using the crystallized glass substrate of 0.01 wt% (Example 4), 0.1 wt% (Example 5), 0.25 % By weight (Example 6), 0.5% by weight (Example
7), a crystallized glass substrate for an information recording medium and an information recording medium (magnetic disk) were respectively formed in the same manner as in the above example, except that the amounts were 1.0% by weight (Example 8) and 2% by weight (Reference Example 1).
Ten sheets were produced at a time. The results are shown below. Incidentally, the surface roughness of the main surface of the crystallized glass substrate after final polishing,
Ra = 0.3 nm, Rmax = 3.2 nm, silicic acid treatment temperature was 45 ° C., and treatment time was 60 seconds.

[0148]

[Table 7]

Thus, it can be seen that the surface roughness Rmax increases as the concentration of silicic acid increases. When the concentration of silicic acid exceeds 1.0% by weight (Example
6, 7 and Reference Example 1), it can be seen that the standard deviation of the surface roughness of the 10 treated crystallized glass substrates is increased, which is more variable than in the case of 0.01 to 1.0% by weight. This indicates that the controllability of the surface roughness was deteriorated due to the increase in the concentration of silicic acid. Note that the crystal grains of the crystallized glass of Examples 4 to 8 and Reference Example 1 have a particle diameter of 100 nm or less, and the areal density of crystal particles having a particle diameter of 10 nm or more is 10 ⁷ to 10 ⁹ pieces /. mm ² and the average is 5.5
× 10 ⁸ pieces / mm ² . Other measured values such as Young's modulus and crystallinity were not different from those in Example 1-1. Further, as a result of glide height test of each medium of Examples 4 to 8 and Reference Example 1, each result was 30 nm or less (Examples 4 to 8).
About 10 nm or less for Reference Example 1 and 30 nm or less for Reference Example 1).
Excellent slidability was obtained.

(Examples 9 to 11, Reference Example 2)
Using the crystallized glass substrate of No. 1, the mixed acid containing silicic hydrofluoric acid after polishing was mixed with 0.25% by weight hydrofluoric acid + 0.03% by weight hydrofluoric acid (Example 9), 0.25% by weight of hydrofluoric acid + 0.1% by weight of hydrofluoric acid. Acid (Example 10), 0.25% by weight hydrofluoric acid + 0.25% by weight hydrofluoric acid (Example 11), 0.25% by weight hydrofluoric acid + 0.5% by weight
Except for using hydrofluoric acid (Reference Example 2), 10 pieces of a crystallized glass substrate for an information recording medium and 10 pieces of an information recording medium (magnetic disk) were produced in the same manner as in the above Examples. The results are shown below. In addition, the surface roughness of the main surface of the crystallized glass substrate after final polishing was Ra = 0.3 nm, Rmax = 3.2 nm, the silicic acid treatment temperature was 45 ° C., and the treatment time was 60 seconds.

[0151]

[Table 8]

Thus, it can be seen that as the concentration of hydrofluoric acid in the mixed acid increases, the surface roughness Rmax increases. The ratio of hydrofluoric acid to hydrofluoric acid (weight% ratio)
Exceeds 1: 1 (Reference Example 2), the standard deviation of the surface roughness of the 10 treated crystallized glass substrates is increased, and 1: 1 to 1:10
It can be seen that there is variation compared to the case of. this is,
This indicates that the controllability of the surface roughness is deteriorated because the concentration of hydrofluoric acid in the mixed acid is increased. Note that the crystal grains of the crystallized glass substrates of Examples 9 to 11 and Reference Example 2 had a particle diameter of 100 nm or less, and a particle diameter of 10 n.
The areal density of crystal grains of m or more was in the range of 10 ⁷ to 10 ⁹ grains / mm ² , and the average value was 5.5 × 10 ⁸ grains / mm ² . Other measured values such as Young's modulus and crystallinity were not different from those in Example 1-1. In addition, as a result of the glide height test of each medium of Examples 9 to 11 and Reference Example 1, each result showed a low flying height of 30 nm or less (10 nm or less for Examples 9 to 11 and 30 nm or less for Reference Example 2). Was stably realized, and excellent slidability was obtained without generation of adsorption.

In the above Examples including Example 1, polishing was performed after heat treatment for crystal nucleus growth, and protrusions (continuous phase) were formed on the surface by utilizing the difference in hardness between the crystal phase and the glass phase (continuous phase). Crystal grains which partially protrude from the crystal grains). This polishing is only one applied example, and it can be replaced by a so-called sputter etching method in which a glass substrate is set in a vacuum and bombarded with Ar ions at a high speed to perform etching. Also, A1 ₂ O ₃
It is also possible to apply a method called so-called sandblasting, in which fine particles of SiC or SiC are sprayed together with air.

[0154]

As described above, according to the present invention, there is provided a crystallized glass substrate for an information recording medium which has excellent sliding reliability, has a surface property enabling high recording density, and has high rigidity. And an information recording medium using the substrate can be provided. According to the present invention, the suction between the write / read head and the surface of the information recording medium is prevented, and there is no large projection that hinders the reduction of the distance between the write / read head and the surface of the information recording medium. A small and highly rigid information recording medium substrate is obtained,
In addition, the suction between the write / read head and the surface of the information recording medium is prevented, and there is no large projection that hinders the reduction of the distance between the write / read head and the surface of the information recording medium. An information recording medium with a high recording density can be obtained.

[Brief description of the drawings]

FIG. 1 shows the relationship between the surface roughness Rmax and the etching time of the crystallized glass of Example 1 etched with a mixed acid of 0.25% hydrofluoric acid and 0.25% silicofluoric acid.

FIG. 2 shows a transmission electron microscope (TEM) of the crystallized glass substrate of Example 1-1.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G059 AA09 AC01 BB04 BB15 BB16 4G062 AA11 BB01 CC01 CC09 CC10 DA05 DA06 DB03 DB04 DC01 DD01 DE01 DF01 EA01 EA02 EA03 EB01 EB02 EB03 EC01 EC02 EC03 ED04 EE05 EE03 EF03 EG02 EG03 FA01 FB03 FB04 FC01 FC02 FC03 FD01 FE01 FF01 FG01 FH01 FJ01 FJ02 FJ03 FK01 FL01 GA01 GB01 GB02 GC01 GD01 GE01 GE02 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 KK01 JJ01 JJ01 JJ01 5D112 AA02 BA03 BA09

Claims (10)

[Claims] 1. A method for producing a glass substrate for an information recording medium comprising crystallized glass in which crystal particles are dispersed in a continuous phase of amorphous glass, wherein the crystallized glass substrate whose main surface is polished is used. For an information recording medium, which is subjected to a surface treatment using an aqueous solution containing silica hydrofluoric acid to control the surface roughness of irregularities formed on a main surface of a substrate which contributes to sliding characteristics with a recording / reproducing head. A method for manufacturing a glass substrate. 2. The information recording medium according to claim 1, wherein the surface treatment causes a part of crystal grains contained in the crystallized glass substrate to partially protrude from a continuous phase on the main surface. Of manufacturing glass substrates for use. 3. The crystallized glass substrate is obtained by melting a glass raw material and forming the obtained molten glass into a glass substrate.
3. A crystal nucleus generation heat treatment step for generating crystal nuclei of the obtained glass substrate, and a crystal nucleus growth heat treatment step for growing the crystal nuclei to a predetermined size. Of manufacturing a glass substrate for an information recording medium. 4. The surface treatment is performed under the condition that the surface roughness (maximum height) Rmax of the main surface of the substrate is 1 to 30 nm.
4. The method for producing a glass substrate for an information recording medium according to any one of items 3 to 3. 5. The aqueous solution containing silica hydrofluoric acid is 0.01 to 1.
It comprises 0% by weight of silicic acid.
5. The method for producing a glass substrate for an information recording medium according to any one of 4. 6. The method for producing a glass substrate for an information recording medium according to claim 1, wherein the aqueous solution containing hydrofluoric acid contains hydrofluoric acid and hydrofluoric acid. 7. Ratio of silicic acid and hydrofluoric acid (weight% ratio)
The method according to claim 6, wherein the ratio is 1: 1 to 10: 1. Wherein said nucleation heat treatment process, the surface density of the crystal nuclei serving as the crystal grains present in the main surface of the substrate ¹⁰⁶ / mm
² and 10 ⁹ / mm ² or less, and the crystal nucleus growth heat treatment step is performed under the condition that the crystal nuclei are grown to crystal grains having a grain size of 1000 nm or less. A method for manufacturing a glass substrate for an information recording medium according to claim 1. 9. The glass for an information recording medium according to claim 1, wherein a surface roughness Ra of a main surface of the polished crystallized glass substrate is 2 nm or less. Substrate manufacturing method. 10. An information recording medium characterized by comprising at least an information recording layer formed on a main surface of a glass substrate for an information recording medium obtained by the production method according to claim 1. Production method.