JP2003346316A - Information-recording medium, manufacturing method of glass substrate for the information recording medium and the glass substrate for information recording medium manufactured by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording medium which decreases the take-off height (TOH) in an HDD, for example, and to provide the manufacturing method of a glass substrate for the information recording medium and the glass substrate for the information recording medium manufactured by the method. <P>SOLUTION: The surface shape of the information recording medium is measured in a prescribed area with an optical interferometer or an AFM, to conduct line analysis in the direction along the circumference, the product of a PSD, corresponding to a prescribed wavelength ν and frequency f being the reciprocal of the prescribed wavelength ν, that is, PSD×f, is computed, and the maximum value of PSD×f is at most a prescribed value. Using this, waviness components which can be an obstacle to a flying head are eliminated, and TOH is set to 4.5 nm or smaller. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an information recording medium, a method for producing a glass substrate for the information recording medium, and a glass substrate for an information recording medium produced by the method.
In particular, the present invention relates to an information recording medium whose surface shape is evaluated by a power spectrum, a method for manufacturing a glass substrate for the information recording medium, and a glass substrate for an information recording medium manufactured by the method.

[0002]

2. Description of the Related Art In recent years, digitization of information has been remarkably progressing, and various information recording apparatuses for recording digitized information on information recording media have been developed and manufactured.
These information recording media are being improved at an ever-increasing pace, and the recording capacities of these information recording media and the recording speed and reproduction speed of the information recording device are increasing at an annual rate of about ten percent. In such a situation, the most widely used information recording device at present is a hard disk drive (Hard Disk Drive).
Disk Drive: hereinafter may be abbreviated as “HDD”), and the improvement progress speed of this HDD is higher than that of other information recording devices.

[0003] A hard disk medium (hereinafter, sometimes referred to as a "disk") has an information recording layer formed on a disk substrate, and digitized information is recorded (written) on the information recording layer.

[0004] There are a CSS (contact start stop) method and a ramp load method as the load / unload method of the magnetic head in the HDD. In the CSS method, when the disk is rotating, the magnetic head glides over the information recording area of the disk,
When the disk starts or stops rotating, it slides on the CSS zone of the disk. Note that C
In the SS system, the magnetic head and the disk are in contact while the disk is stopped.

[0005] Here, the CSS zone of the disk refers to an area in which uniform unevenness having a height of several tens nm is intentionally provided mainly along the inner or outer circumference of the disk.

In the ramp load method, when the disk is rotating, the magnetic head glide on the disk,
When the disk stops rotating, the magnetic head is stored in the storage position. In the ramp load method, the magnetic head does not come into contact with the disk even when the disk is stopped.

Hereinafter, the minimum flying height of the magnetic head is referred to as take-off height (hereinafter sometimes abbreviated as “TOH”). When the TOH is reduced, the glide height can be reduced. Note that the take-off height may be called a touch-down height.

In the CSS method or the ramp load method, when the hard disk is rotating, the magnetic head glides over the information recording area with the TOH. It is required to be smaller.

When recording and reproducing information on a disk using a magnetic head, when large irregularities are formed on the surface of the hard disk, the magnetic head contacts or collides with a large convex portion on the surface of the hard disk during rotation of the hard disk. However, head fluctuation during flight becomes large, so that a head crash is likely to occur.

Further, even if a head crash does not occur, the contact or collision generates heat in the magnetic head, and the generated heat causes the magnetic head to detect an abnormal signal, that is, a so-called thermal asperity.
ity) easily occurs.

Particularly, in recent magnetic heads, an MR (magnetoresistive) head or a GMR which reads data with high precision
(Giant magnetoresistive) heads are the mainstream, and since reading is performed with high precision, a head that does not easily generate thermal asperity is required.

Conventionally, an aluminum substrate has been mainly used as a substrate for a hard disk, but is now being replaced by a glass substrate. When the hard disk substrate is a glass substrate, highly accurate polishing can be performed, so that the gliding height of the head can be reduced. As a result, the distance between the magnetic head and the magnetic head can be narrowed, and the magnetic head can be read with high accuracy. As described above, the information recording medium substrate is required to have high surface flatness and surface smoothness, and is also required to have high rigidity.

An information recording medium using such a glass substrate is manufactured by sequentially performing the following manufacturing steps.

FIG. 10 is a process chart showing a conventional method for manufacturing a recording medium using a glass substrate for an information recording medium.

In FIG. 10, in step S21, a sheet-like glass is produced from a base glass made of aluminosilicate glass, and a donut-like work is extracted from the sheet-like glass (work extracting step).

Next, a predetermined chamfering process is performed on the outer peripheral end surface and the inner peripheral end surface of the extracted work, and the work is polished using a rotating nylon brush or an alumina abrasive polishing agent (end surface polishing step, step S22), and Then, the information recording surface of the work whose inner and outer peripheral end surfaces have been polished is polished using a polisher made of a hard cloth while using a cerium oxide slurry (recording surface polishing step, step S23).

The work whose information recording surface has been polished is subjected to a chemical strengthening treatment and a cleaning treatment (chemical strengthening treatment step) to obtain a glass substrate for an information recording medium (step S2).
4). In addition, the manufactured glass substrate is inspected for surface flatness and the like as necessary.

A magnetic film or an optical recording film is formed on this glass substrate to form an information recording medium (film forming step, step S2).
5) Perform a predetermined inspection (inspection process, step S2)
6) End the production of the information recording medium.

In order to evaluate the surface flatness of a glass substrate or an information recording medium, for example, an average roughness R
a, the root mean square roughness RMS, and values such as the average roughness of undulations or micro undulations measured only in a specific wavelength range by applying a cutoff may be measured.

Here, the average roughness Ra is defined by the JIS standard (JIS B 0601) as the center line average roughness, and is the average of the absolute values of the deviation from the center line to the measurement curve. The root-mean-square roughness RMS is defined as the root-mean-square roughness (RMS) in the JIS standard (JIS B 0601), and the square of the deviation from the center line to the roughness curve (measurement curve) is used as the evaluation length. The square root of the value integrated over an interval and averaged over that interval.

In addition, instead of the polishing using the polisher in step S23, a method has been proposed in which a surface layer of a glass substrate for an information recording medium is polished by using a suede (artificial leather). (For example, JP-A-2000-53450) (first conventional technique). According to the first prior art, it is stated that an information recording medium using a glass substrate for an information recording medium having high surface smoothness can be manufactured.

Further, in the inspection step after the step S24 and the inspection step in S26, instead of the method of evaluating the undulation, the minute undulation, etc. by the wavelength, the method of evaluating the undulation component having a longer wavelength than them is as follows. Wavelength ^{2 to} 4000 μm in predetermined area 50 to 4000 μm ²
Average height of micro swelling, or wavelength 300-5000
A method has been proposed in which evaluation is performed using the average height of the swelling of μm as an index (for example, JP-A-2000-3483).
30, JP-A-2000-348331, JP-A-2000-348332, etc.) (second conventional technique).

Japanese Patent Application Laid-Open No. 2000-31224 discloses that a wavelength ν or a frequency f
Power Spectral Density
(ty: hereinafter, referred to as “PSD”) has been proposed to evaluate surface flatness (third conventional technique).

By the way, in the flatness of the disk surface for the HDD, there are the following types of swelling that hinder the flight of the magnetic head. That is, the wavelength is several mm
Undulation with irregularities of about 20 mm, wavelength of 2-4
Micro undulations with irregularities of about 000 μm, wavelength 1
Micro-roughness having an irregular shape of 00 μm or less (hereinafter, these are simply referred to as “unelli components” in the present specification). However, clear definitions and standards have not been established for these wavelength regions.

[0025]

However, as in the first prior art, in the glass substrate for an information recording medium, when the surface flatness is evaluated, for example, the average roughness Ra and the root mean square roughness are measured. The substrate surface cannot be sufficiently flattened only by reducing the values such as the degree of RMS and the average roughness of cut-off undulations or minute undulations. The reason is that undulation components having various periods overlap on the surface of the glass substrate for an information recording medium that has been subjected to polishing or the like. As a result, there is a limit to reducing the gliding height of the magnetic head in the HDD.

For the overlapping undulation components, the average roughness such as the average roughness Ra, the root-mean-square roughness RMS, and the average roughness of the cut-off undulation or the fine undulation is measured, and the surface roughness is measured. Just by evaluating flatness,
The surface flatness cannot be sufficiently expressed.

In the second prior art, the average height of the undulation component is used as the evaluation of the surface flatness.
Since these are also averaged values to the last, the contribution of the undulation component of a specific wavelength cannot be sufficiently described.

Furthermore, since the averaging is performed in the two-dimensional direction, for example, the contribution of the magnetic head flight direction of the HDD (circumferential direction of the information recording medium) and the direction perpendicular to the magnetic head flight (radial direction of the information recording medium) Cannot be separated from the contribution of

This is particularly important in evaluating the flight characteristics of the magnetic head on a disk on which a circumferential texture is formed. That is, on the surface on which the circumferential texture is formed, the undulation component differs in the magnetic head flight direction (circumferential direction) and the vertical direction (radial direction). Unable to sufficiently describe the swelling that hinders the flight.

In the third prior art, a PSD is generally used.
Comparing the functions as they are, the PSD function has a slope of 1 / f (or 1 / f ^{2 in} some cases) as its baseline (FIG. 11). it can. However, it is difficult to quantitatively compare the intensity (power) in a wavelength region near a specific wavelength, and TOH cannot be easily evaluated.

An object of the present invention is to provide an information recording medium capable of reducing undulation and TOH which hinders flight of a magnetic head in an HDD, for example, and a method of manufacturing a glass substrate for an information recording medium used in the information recording medium. Is to do.

[0032]

According to a first aspect of the present invention, there is provided an information recording medium having a recording layer formed on a substrate. An information recording medium having at least one recording layer formed on a substrate, wherein a surface shape of the recording layer is measured at a predetermined wavelength in a predetermined region of the surface, and a power spectrum density corresponding to the predetermined wavelength and The maximum value of the product of the reciprocal of the predetermined wavelength is not more than a predetermined value.

According to the information recording medium of the present invention, the maximum value of the product of the power spectral density corresponding to the predetermined wavelength and the reciprocal of the predetermined wavelength is equal to or less than the predetermined value.
An undulation component that hinders the flight of the magnetic head is reduced, so that an information recording medium with a low TOH can be provided.

The information recording medium according to the second aspect is the first aspect.
In the information recording medium described above, the measurement is performed using an optical interferometer, and the area of the predetermined region is 0.1 mm square to 5 mm.
mm square, the predetermined value is 1600 cm ²
It is characterized by the following.

According to the information recording medium of the second aspect, since the predetermined value is 1600 cm ² or less, the TOH is set to 4.
It can be 5 nm or less.

The information recording medium according to the third aspect is the second aspect.
In the information recording medium, the predetermined value is 1300
cm ² or less.

According to the information recording medium of the third aspect, since the predetermined value is 1300 cm ² or less, the TOH is set to 4.
It can be 0 nm or less.

The information recording medium according to the fourth aspect is the first aspect.
In the information recording medium described above, the area of the predetermined area is 1
When the square is from 0 μm square to 200 μm square, the predetermined value is 1100 cm ² or less.

According to the information recording medium of the fourth aspect, since the predetermined value is 1100 cm ² or less, the TOH is set to 4.
It can be 5 nm or less.

The information recording medium according to the fifth aspect is the fourth aspect of the present invention.
In the information recording medium described above, the predetermined value is 900c
m ² or less.

According to the information recording medium of the fifth aspect, since the predetermined value is 900 cm ² or less, TOH is set to 4.0.
nm or less.

The information recording medium according to the sixth aspect is the first aspect.
In the information recording medium described above, the measurement is performed by scanning with a probe of an atomic force microscope, and when the area of the predetermined region is 1 μm square to 50 μm square, the predetermined value is 100 nm ² or less. There is a feature.

According to the information recording medium of the sixth aspect, since the predetermined value is 100 nm ² or less, TOH is set to 4.5.
nm or less.

[0044] The information recording medium according to claim 7 provides the information recording medium according to claim 6.
In the information recording medium described above, the predetermined value is 80 nm
It is characterized by being ² .

According to the information recording medium of the present invention, since the predetermined value is 80 nm ² or less, TOH is reduced to 4.0 n.
m or less.

The information recording medium according to the eighth aspect is the first aspect.
8. The information recording medium according to any one of items 1 to 7,
A circumferential texture is formed on a main surface of the recording layer or the substrate.

According to the information recording medium of the present invention, since the recording layer has magnetic anisotropy in the circumferential direction and the radial direction of the information recording medium due to the circumferential texture, the information recording density is improved. be able to.

The method of manufacturing a glass substrate for an information recording medium according to claim 9, which is a second embodiment of the present invention, is a method of manufacturing a glass substrate for an information recording medium having a recording layer formed on a substrate. The surface of 100% modulus is 7840-24500 kPa (80-250 kg / cm
² ) The method includes a step of polishing a resin by a polishing member that has been processed.

However, 100% modulus refers to the force required to stretch a sample having a cross-sectional area of 1 cm ² to twice its length.

According to the method for manufacturing a glass substrate for an information recording medium according to the ninth aspect, it is possible to remove undulation components, prevent head crash and thermal asperity, and reduce TOH. can do.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a glass substrate for an information recording medium according to the ninth aspect, wherein the polishing member is set at 0.0333 / sec.
It is characterized by rotating at a rate of 25 / sec (2 rpm to 15 rpm).

According to the method for manufacturing an information recording medium according to the tenth aspect, it is possible to reduce generation of undulation components and fine scratches on the surface of the glass substrate.

According to a method of manufacturing an information recording medium according to an eleventh aspect, in the method of manufacturing a glass substrate for an information recording medium according to the ninth aspect, the polishing step has a maximum particle size of 1 to 3 μm.
Characterized in that a slurry containing an abrasive is used.

According to the method of manufacturing an information recording medium according to the eleventh aspect, it is possible to remove undulation components on the surface of the glass substrate and to reduce the occurrence of fine scratches.

According to a twelfth aspect of the present invention, in the method for manufacturing a glass substrate for an information recording medium according to the ninth aspect, in the polishing step, the one having a maximum particle size of 1 to 3 μm is used. It is characterized in that a slurry containing an abrasive that is 10% or less of the mass of the slurry solid content is used.

According to the method for manufacturing a glass substrate for an information recording medium according to the twelfth aspect, it is possible to remove undulation components on the surface of the glass substrate and to reduce the occurrence of fine scratches.

According to a thirteenth aspect of the present invention, there is provided a method of manufacturing a glass substrate for an information recording medium, wherein the polishing step comprises the step of polishing the silica having a particle size of 0.01 to 1 μm. Characterized by using a slurry containing

According to the method for manufacturing a glass substrate for an information recording medium according to the thirteenth aspect, it is possible to remove undulation components on the surface of the glass substrate and to reduce the occurrence of fine scratches. Further, the impact of the abrasive on the glass substrate can be reduced.

According to a fourteenth aspect of the present invention, in the method for manufacturing a glass substrate for an information recording medium according to the ninth aspect, the polishing member has a 100% modulus of 9800 to 19600 kPa (100 to 100 kPa). 20
0 kg / cm ² ) resin is processed.

According to the method of manufacturing a glass substrate for an information recording medium according to the present invention, undulation components can be removed, head crash and thermal asperity can be prevented, and TOH can be reduced. can do.

A glass substrate for an information recording medium according to claim 15, which is a third embodiment of the present invention, is a glass substrate for an information recording medium manufactured by the method for manufacturing a glass substrate for an information recording medium according to claims 9 to 14. The surface shape of the substrate is measured at a predetermined wavelength in a predetermined region of the surface, and a maximum value of a product of a power spectral density corresponding to the predetermined wavelength and a reciprocal of the predetermined wavelength is set to a predetermined value or less. It is characterized by the following.

According to the glass substrate for an information recording medium of the present invention, the maximum value of the product of the power spectral density corresponding to the predetermined wavelength and the reciprocal of the predetermined wavelength is equal to or less than the predetermined value. In the information recording medium on which the recording layer is formed, the undulation component that hinders the flight of the magnetic head is reduced, so that an information recording medium with a low TOH can be provided.

A glass substrate for an information recording medium according to claim 16
The plate may be a glass substrate for an information recording medium according to claim 15.
And the measurement is performed using an optical interferometer, and
When the area of the area is 0.1 mm square to 5 mm square,
The predetermined value is 1600 cm ^TwoIt is characterized by the following
I do.

According to the glass substrate for an information recording medium of the present invention, the predetermined value is 1600 cm ² or less.
Can be set to 4.5 nm or less.

A glass substrate for an information recording medium according to a seventeenth aspect is the glass substrate for an information recording medium according to the sixteenth aspect, wherein the predetermined value is 1300 cm ² or less.

According to the glass substrate for an information recording medium of the present invention, the predetermined value is 1300 cm ² or less.
Can be set to 4.0 nm or less.

The glass substrate for an information recording medium according to the eighteenth aspect is the glass substrate for an information recording medium according to the fifteenth aspect, wherein the area of the predetermined region is 10 μm square to 200 μm.
When square, the predetermined value is 1100 cm ² or less.

According to the glass substrate for an information recording medium of the present invention, the predetermined value is 1100 cm ² or less.
Can be set to 4.5 nm or less.

A glass substrate for an information recording medium according to a nineteenth aspect is the glass substrate for an information recording medium according to the eighteenth aspect, wherein the predetermined value is 900 cm ² .

A glass substrate for an information recording medium according to claim 19
According to the plate, the predetermined value is 900cm ^TwoSince
In an information recording medium on which a recording layer is formed, TOH is used.
It can be set to 4.0 nm or less.

According to a twentieth aspect of the present invention, in the glass substrate for an information recording medium according to the fifteenth aspect, the measurement is performed by scanning with a probe of an atomic force microscope, and Area is 1 μm square to 5
When the square is 0 μm, the predetermined value is 100 nm ²
It is characterized by the following.

A glass substrate for an information recording medium according to claim 20.
According to the plate, the predetermined value is 100 nm ^TwoSince
In an information recording medium on which a recording layer is formed, TOH is used.
It can be 4.5 nm or less.

A glass substrate for an information recording medium according to a twenty-first aspect is the glass substrate for an information recording medium according to the twentieth aspect, wherein the predetermined value is 80 nm ² .

According to the glass substrate for an information recording medium of the present invention, the predetermined value is 80 nm ² or less.
It can be 0 nm or less.

The glass substrate for an information recording medium according to claim 22 is the glass substrate for an information recording medium according to any one of claims 15 to 21, wherein:
It is characterized in that a circumferential texture is formed.

According to the glass substrate for an information recording medium of the present invention, in the information recording medium having the recording layer formed thereon, the recording layer is formed in the circumferential direction and the radial direction of the information recording medium by the circumferential texture. Has magnetic anisotropy, so that the information recording density can be improved.

[0077]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies to achieve the above object, the present inventor has found that, in an information recording medium having a recording layer formed on a substrate, the surface shape of the recording layer is a predetermined shape of the surface. In a region, measured at a predetermined wavelength, and the maximum value of the product of the power spectrum density corresponding to the predetermined wavelength and the reciprocal of the predetermined wavelength is set to a predetermined value or less, for example, HD
The present inventor has found that it is easy to evaluate the presence or absence of a swelling component that hinders the flight of the magnetic head D, and that an information recording medium with a low TOH can be provided.

The present inventor further provides a method of manufacturing a glass substrate for an information recording medium having a recording layer formed on a substrate, wherein the surface of the glass substrate has a 100% modulus of 7840.
Polishing with a polishing member processed from a resin having a pressure of ２４24500 kPa (80 to 250 kg / cm ² ) can reduce, for example, undulation components which hinder the flight of the magnetic head of the HDD. As a result, it has been found that head crash and thermal asperity can be prevented and TOH can be reduced.

The present invention has been made based on the results of the above research.

Hereinafter, a method for manufacturing an information recording medium according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a process chart of a method for manufacturing an information recording medium according to an embodiment of the present invention. Note that the present invention is not limited to such an embodiment.

[0082]Base glass selection process (Step S1) First, as a base glass for glass substrates for information recording media,
Is, for example, SiO_Two, Na_TwoO and CaO are the main components
Soda lime glass, SiO_Two, A1 _TwoO_Three, N
a_TwoO, and Li_TwoAlumino silique containing O as main component
Glass, borosilicate glass, Li_TwoO-SiO_Two
Glass, Li_TwoO-A1_TwoO_Three-SiO_TwoGlass,
Is RO-A1_TwoO_Three-SiO_TwoGlass (R = Mg, C
a, Sr, Ba, Zn, Ni, Mn, etc.)
And ZrO as another component._Two, TiO_Two, And S
iO_TwoGlass for chemical strengthening including
Crystallized glass that has not been subjected to a chemical treatment is selected.

The selected base glass for a glass substrate is preferably made of crystallized glass because of its high surface smoothness, easy surface treatment, and high elasticity, rigidity and strength.

On the other hand, in terms of high surface smoothness, it is preferable to use amorphous glass rather than crystallized glass, and particularly to use aluminosilicate glass in terms of high mechanical strength and impact resistance. Is preferred.

Further, it is preferable to use a glass for chemical strengthening in that the surface layer of the glass substrate can be modified, but a compressive stress layer is formed by previously performing chemical strengthening on the surface of the base glass. It may be made of chemically strengthened glass. The base glass for the glass substrate is not particularly limited to those described above.

Sheet glass production step (step S2) Sheet glass having a predetermined thickness is produced from the selected base glass for a glass substrate. The production method of the sheet-like glass may be any production method, for example, a float method for molding on molten metal, a down-draw method for molding using gravity, or re-melting and molding ingot glass. The redraw method may be used.

Work Extraction Step (Step S3) For example, a sheet-like glass having an aluminosilicate composition produced by a float method is cut simultaneously along the inner diameter and the outer diameter using a cemented carbide or diamond cutter. . The outer diameter is set slightly larger than the outer diameter of the glass substrate product dimensions, and the inner diameter is set slightly smaller than the glass substrate product dimensions. By simultaneously cutting along the inner diameter and the outer diameter in this manner, a donut-shaped work having good concentricity of the outer diameter and the inner diameter is extracted.

A method for extracting a donut-shaped work is as follows.
The method is not limited to the above-described simultaneous cutting method.First, a sheet-like glass is cut along an outer diameter, and then, a method of punching a hole along an inner diameter using a cylindrical diamond grindstone, or a pressing method. May be used to produce a sheet-like glass so as to have a desired outer diameter, and then punch holes along the inner diameter using a cylindrical diamond grindstone.

Edge Polishing Step (Step S4) Next, the glass substrate of the extracted work is ground on the inner and outer end faces of the work in order to accurately match the dimensions of the product. To perform this grinding, a grinding wheel to which diamond abrasive grains are attached is used. Grinding is performed in two steps: grinding using a grinding wheel having diamond abrasive grains having a roughness of # 325 attached thereto, and grinding processing using a grinding wheel having diamond abrasive grains having a roughness of # 500 attached thereto. Consists of

At the same time as the grinding of the end face, the chamfering of the end face is also performed using a grinding wheel manufactured so that the glass substrate product has a predetermined size. The grinding and chamfering of the end face may be performed simultaneously or separately. Further, the roughness of the diamond abrasive grains used may be another roughness depending on the required quality of the glass substrate product. Further, in the work extraction process of step S3, when the work is extracted to a size close to the size of the glass substrate product, it goes without saying that there is no need to perform two-stage grinding in this process. .

Next, in order to smooth the roughness of the chamfered surface of the end surface, the end surface is polished using a slurry containing cerium oxide as an abrasive.

Lapping Step (Step S5) Rough polishing (lapping) is performed prior to precision polishing of the information recording surface of the work described later. This is because the thickness of the work is made uniform, the flatness of the work is improved, the undulation component is improved, and defects such as cracks and scratches inevitably generated on the information recording surface of the work are removed.

More specifically, while supplying a slurry containing alumina abrasive grains having a solid content of about 20% by mass between the metal platen of the polishing machine and the information recording surface of the work, The information recording surfaces (upper surface and lower surface) of the work are simultaneously subjected to lapping. The lapping process includes two steps, a lapping process using a slurry containing alumina abrasive grains having a roughness of # 600 and a lapping process using a slurry containing alumina abrasive grains having a roughness of # 1000.

This lapping may be performed before the end face polishing step of step S4, or
The first-stage rough grinding may be performed before the end surface polishing process, and the second-stage rough grinding may be performed after the end surface polishing process.

In the lapping step in the present production method,
Since the processing speed at which the lapping process is performed is high, it is common to polish the work to near the final thickness of the glass substrate product.

When the thickness of the base glass is close to the final thickness of the product, there is no need to perform lapping in two steps, and lapping using a slurry containing alumina abrasive grains having a roughness greater than # 600. May be applied in one stage. Instead of lapping using slurry, lapping may be performed on the information recording surface of the work using a fixed grindstone in which diamond abrasive grains or alumina abrasive grains are embedded.

After the lapping process, the work to which the used abrasive and slurry are adhered is subjected to a cleaning treatment using water, a detergent, or the like. When performing this cleaning treatment, it is preferable to apply ultrasonic waves having an appropriate frequency.
As a result, the abrasive and the slurry attached to the surface of the work easily fall off.

This step may be omitted according to the degree of surface flatness and undulation required for the glass substrate product.

Primary Polishing Step (Step S6) Next, when a lapping step is performed, an abrasive is used to improve the surface roughness of the unevenness generated on the work surface and to remove cracks and scratches. Primary polishing is performed on the information recording surface of the work using a slurry containing cerium oxide as a main component. This slurry has an average particle size of 1.5μ.
It contains lanthanoid oxide (such as cerium oxide and lanthanum oxide) having a concentration of about 20 m% and a concentration of about 20% by mass.
Specifically, the slurry is supplied to a polishing machine to perform primary polishing on the information recording surface of the work.

The polishing machine has a polishing pad made of urethane foam resin impregnated with cerium oxide adhered to the surface in contact with the work, and a load of about 49 N (5 kgf) is applied to the work via the polishing pad. And simultaneously grind the upper and lower surfaces of the work, and operate the grinder until the work has a predetermined thickness.

After the primary polishing, the work to which the used abrasive and slurry are adhered is subjected to a cleaning treatment using water, a detergent or the like. When performing this cleaning treatment, it is preferable to apply ultrasonic waves having an appropriate frequency. By applying the ultrasonic wave, the abrasive and the slurry attached to the surface of the work easily fall off.

Precision Polishing Step (Step S7) Next, precision polishing is performed as secondary polishing.

The polishing pad has a nap layer as the outermost surface layer, and the nap layer has 1 as an index of surface hardness.
00% modulus is 7840 to 24500 kPa (80
After melting and foaming a resin having a hardness in the range of about 250 kg / cm ² ), a polishing member manufactured by shaving the outermost surface to expose pores is used. By using such a resin having a large 100% modulus for the nap layer, since the surface layer of the nap layer is microscopically hard when precision polishing is performed, the wavelength of the information recording surface of the work is 0.1 mm. The swelling component of 1 to 5 mm can be improved.

100% modulus is 7840-2450
0 kPa (80-250 kg / cm ^Two),
The surface of the nap layer is microscopically hard. For example, polyurethane
Microscopically, the amorphous resin and the amorphous layer
It is also composed of a crystal layer with large hardness,
100% Modulus can be used as a target.

For example, a resin having a high crystallinity, ie, 1
A nap layer made of a resin having a large modulus of 00% has a property that it is hard when viewed microscopically and soft when viewed macroscopically due to the pores contained in the nap layer. Although the detailed mechanism is not clear, it is considered that the microscopic hardness of the nap layer is effective for removing undulations having a wavelength of 0.1 to 5 mm.

The larger the 100% modulus is, the more preferable. However, if the 100% modulus is too large, it becomes difficult to uniformly mold a resin made of a foam. 100%
Modulus is 24500 kPa (250 kg / cm ² )
If it exceeds, it is difficult to form a uniform and flat nap layer, and fine scratches are likely to occur when precision polishing is performed.

The 100% modulus is 9800 to 1960
When the pressure is in the range of 0 kPa (100 to 200 kg / cm ² ), the undulation component having a wavelength of 0.1 to 5 mm on the information recording surface of the work is most preferably improved. The 100% modulus is 9800 to 19600 kPa (100 to 200 kg / c
In the range of m ² ), since the hardness of the surface layer of the nap layer is sufficiently large and the homogeneity is high, it is considered that undulation is most improved.

The lower layer on which the nap layer is formed on the upper surface is not particularly limited, but may be, for example, a base layer in a suede type polishing pad in which the nap layer is formed on the base layer. Further, a platen provided in the polishing machine may be used, and a nap layer may be directly attached to the platen with an adhesive. A nonwoven fabric or a resin sheet can be used as a base layer in a suede type polishing pad.

As a material for the nonwoven fabric, a urethane resin or the like can be used, and as a material for the resin sheet, vinyl chloride, PET, or the like can be used. The thickness of the nap layer is not particularly limited, for example, 0.2 to 1 mm
Can be used. The opening diameter of the nap layer is not particularly limited, and for example, those having a diameter of 30 to 100 μm can be used.

The rotation speed range of the rotation of the carrier supporting the work is set to 0.0333 / sec to 0.25 / sec (2 rpm).
m to 15 rpm). When performing precision polishing, the rotation speed of the carrier is set to 0.
It is preferably at least 0333 / sec (2 rpm). As a result, the time required for the polishing pad to perform precision polishing of the work in a certain direction is relatively shortened, and the wavelength is 10 to 50 μm.
The swelling component is less likely to occur. If the rotation speed of the carrier exceeds 0.25 / sec (15 rpm), the load applied to the polishing machine and the carrier increases, and the carrier may not rotate smoothly. Such fine scratches and the like easily occur.

As the polishing liquid, a lanthanoid oxide slurry containing cerium oxide and / or lanthanum oxide as a polishing agent, or a silica slurry containing fine silica particles is used. The lanthanoid-based oxide slurry may contain about 0.01 to 5% of fluorine.

When precision polishing is performed using the slurry, the maximum particle size of the lanthanoid oxide-based slurry solid content is preferably 3 μm or less. Thereby, the undulation component having a wavelength of 1 to 10 μm on the information recording surface of the work is reduced, and the occurrence of polishing unevenness and fine scratches can be prevented. Further, when the particle size of the abrasive is 1
Content of about 3 μm is 1% of the solid content mass of the abrasive.
When the content is 0% or less, the amount of swelling component having a wavelength of 1 to 10 μm is further reduced, which is preferable.

The average particle size of the solid content of the lanthanoid oxide slurry is not particularly limited.
It may be 1 to 1.6 μm. If the average particle size of the abrasive made of a lanthanoid oxide is too small, the polishing efficiency is reduced, or the abrasive particles are agglomerated to easily cause polishing unevenness on the work surface.

When polishing is performed using a slurry containing finely divided silica, commercially available colloidal silica or fumed silica can be used.
Colloidal silica is a slurry in which silica having an average particle size of 0.03 to 0.5 μm is dispersed in a colloidal state. When the colloidal silica having such an average particle diameter is used, colloidal silica does not aggregate even if the average particle diameter of the silica is small, and local polishing unevenness is unlikely to occur.
In particular, the average particle size of silica is not limited.

The work that has been subjected to the precision polishing process can be used as a glass substrate product for an information recording medium as it is.
Unelli has been improved. Since the undulation is improved, the outermost surface of the glass substrate for a hard disk may be subjected to texture processing in a circumferential shape without performing the steps described later.

Next, a simple cleaning process is performed on the abrasive and the slurry that have softly adhered to the surface of the work when the precision polishing is performed. For example, the slurry is switched to water and rinsed, shower cleaning is performed, or the work is picked up and placed in a pure water bath, and then subjected to pure water cleaning while applying ultrasonic waves before stopping the precision polishing process.

In the precision cleaning after the simple cleaning process,
In order to remove the firmly attached abrasive, the surface layer of the work is slightly etched. The etchant is not particularly limited, but an acidic aqueous solution containing hydrofluoric acid or the like can be used. After treatment with an acidic aqueous solution, treat with a commercially available alkaline aqueous solution, rinse in a pure water bath to remove the alkaline aqueous solution, then immerse the work in a pure water bath, rinse, and place in a isopropyl alcohol bath. After immersion to replace the water on the work surface with isopropyl alcohol, the work surface is dried in isopropyl alcohol vapor.

Chemical Strengthening Step (Step S8) Next, a mechanical shock when handling the work, an influence of heat when forming a film such as a magnetic film on the surface of the work, or after being incorporated in the hard disk drive The surface layer of the workpiece is subjected to chemical strengthening treatment in order to increase the reliability such as strength and durability for long-term use. Thus, the strength of the glass substrate can be reliably increased.

Specifically, first, potassium nitrate and sodium nitrate are charged into a chemical strengthening tank, and heated and melted at a temperature of about 400 ° C. to obtain a mixed molten salt. Then, the work is put into the chemical strengthening tank and immersed in the mixed molten salt for several hours. Thus, ion exchange between lithium ions and sodium ions contained in the glass and potassium ions contained in the mixed molten salt is performed.

When an aluminosilicate glass containing Li ₂ O is used as the base glass, 10%
The chemically strengthened layer can be formed to a depth of about 0 μm.

Next, the work is taken out of the chemical strengthening tank,
The workpiece that has been subjected to the chemical strengthening treatment is gradually cooled, and then immersed in pure water or warm water for a long time to dissolve and remove the mixed salt remaining in the surface layer of the workpiece in water.

Scrubbing Step (Step S9) In this step, the workpiece is subjected to scrubbing after precision polishing. The reason after the precision polishing is that if the scrubbing treatment is performed in a state where a large number of large foreign substances such as abrasives are present on the surface of the work, the large foreign substances are rubbed against the work, and the work is easily scratched. . Therefore, it is preferable that this step is a step having high cleanliness, that is, a step subsequent to the cleaning processing step.

When a chemical strengthening process is performed after the texture process, a scrub process is performed after the chemical strengthening process. The reason after the chemical strengthening treatment is that since a foreign substance such as iron adheres to the work, it is preferable to perform a scrub treatment in order to more reliably remove the abnormal projection. Further, it is preferable to perform a cleaning treatment on the work using an acidic aqueous solution after performing the chemical strengthening treatment and before performing a scrub cleaning treatment described later. Thereby, foreign substances and the like can be more completely removed.

More specifically, the surface of the work is scrubbed in the circumferential direction of the work by using a sponge having a shape of a line or a strip in contact with the work. As a method of performing scrubbing with a sponge, a method of holding a work with a cylindrical brush sponge having a cylindrical contact portion with a work and rotating the work and the brush sponge, and a shape of a contact portion with the work having a tape shape are used. A method of holding a work with a sponge and rotating the work and the sponge can be used. A commercially available scrub cleaning device may be used as the device for performing the scrub treatment.

After performing the scrubbing process, a scrub cleaning process is performed. The cleaning liquid for performing the scrub cleaning treatment is not particularly limited, for example, pure water, electrolytic ionic water, ozone water, hydrogenated water, acidic aqueous solution, or alkaline aqueous solution, or a chelating agent, surfactant Agents or salts to which salts have been added can be used. Of these, it is preferable to use an alkaline aqueous solution. Accordingly, an electrostatic repulsion acts between the foreign matter and the work, so that the scrub cleaning process can be performed while preventing the foreign matter from re-adhering to the work.

When performing the scrub cleaning treatment, ultrasonic waves are applied to the work through a cleaning liquid. Thereby, it is possible to prevent the damage to the work, the change in the shape of the texture, and the like. The conditions for performing the scrub cleaning treatment such as the frequency of the ultrasonic wave, the output of the ultrasonic wave, the time for applying the ultrasonic wave, and the temperature of the cleaning liquid are not particularly limited, but usually, the frequency of the ultrasonic wave is 38 kHz or more. The output of the ultrasonic wave is 1W / cm ² or less, and the time for applying the ultrasonic wave is 1
２０20 min, the temperature of the cleaning liquid is 70 ° C. or less.

Thereafter, rinsing is performed using pure water, and the work is dried. The method of rinsing using pure water is not particularly limited, and examples thereof include immersion, immersion while applying ultrasonic waves, showering, and spraying. Also, the method of drying the work is not limited, and any method may be used as long as it performs a process corresponding to a scrub cleaning process as a precision cleaning process, such as spin drying or isopropyl alcohol drying. Good.

Then, a predetermined inspection is performed, and the work that passes the inspection is shipped as a glass substrate for an information recording medium.

Film Forming Process (Step S10) When a hard disk medium is manufactured from an information recording medium glass substrate, at least an underlayer,
A magnetic layer (recording layer) and a protective film are sequentially formed and a film forming process is performed. For example, when the glass substrate has not been subjected to the circumferential texture processing, the magnetic layer may be subjected to the circumferential texture processing. If necessary, a seed layer may be formed between the glass substrate for the hard disk and the underlayer to form a film, or a buffer layer and a shield layer may be formed for each layer to form a multi-layer disk. The film forming process may be performed so that

After the film forming process, a tape burnishing process may be performed. This makes it possible to remove foreign substances and dirt attached to the protective film.

The above-described underlayer, magnetic layer, and protective film include:
The type, film thickness, and method of forming the film are not particularly limited. For example, when a glass substrate is used, a NiAl alloy is used as a seed layer, a Cr or Cr-based alloy is used as an underlayer, and a magnetic layer is used. It is preferable to use a Co-based alloy. Thereby, the recording and reproducing characteristics of the hard disk medium can be secured. As a method of forming a film, a sputtering method is usually preferably used. Thereby, a hard disk medium in which the surface flatness of the glass substrate is maintained as it is can be manufactured.

Inspection Step (Step S11) The surface shape of the manufactured hard disk medium is measured in a predetermined area using an optical interferometer or an atomic force microscope (AFM), and the flying direction of the magnetic head, that is, the circumferential direction is measured. Perform line analysis along.

In the line analysis, a PSD corresponding to a predetermined wavelength ν is calculated (see FIG. 11), and a product PSD × f of the PSD and a frequency f which is the reciprocal of the predetermined wavelength ν is calculated (see FIG. 2). ). Thereby, the baseline of the PSD function can be made horizontal, and the values of the PSD corresponding to the range of the predetermined wavelength ν can be easily compared. Preferably, the line analysis is performed on a plurality of lines, and the results are averaged. Thereby, more accurate line analysis can be performed.

Referring to FIG. 2, a range of a predetermined wavelength ν,
For example, the maximum value of PSD × f corresponding to 1 to 10 μm is
It is about 100 nm ² or less. This value has a good correlation with TOH measured by detection of a piezo signal described later. The maximum value of PSD × f is about 100 nm ²
In the following cases, TOH is 4.5 nm or less.

That is, TOH can be estimated only by calculating PSD × f without measuring TOH using a piezo element. Measurement using a piezo element involves bringing the piezo element into contact with the medium surface.

On the other hand, an optical interferometer or an atomic force microscope (A
Measurement using FM (non-contact mode) is a preferable measurement method because it is not necessary to make contact with the medium surface.

For example, a hard disk medium having a TOH of 4.5 nm or less has excellent recording / reproducing characteristics, reduces undulation that hinders the flight of a magnetic head, has small head fluctuation, and causes a head crash. Hateful. Further, it is a hard disk medium that does not easily generate thermal asperity (hereinafter, this is referred to as having excellent media characteristics).

In this way, it is confirmed that the maximum value of PSD × f on the surface of the medium is equal to or less than the predetermined value, the medium is shipped as a final product, and this processing is completed. The predetermined area and the predetermined value will be described later.

Then, a hard disk medium in which the maximum value of PSD × f on the medium surface is equal to or less than a predetermined value is mounted on a spindle of the HDD, and a magnetic head and the like are mounted to complete a hard disk drive.

In the inspection step of step S11, it was confirmed that the maximum value of PSD × f on the medium surface was not more than a predetermined value. However, the information recording medium manufactured after the scrubbing step of step S9 was completed. Step S1 on a glass substrate
In the same manner as in the first inspection step, it may be confirmed that the maximum value of PSD × f on the substrate surface is equal to or less than a predetermined value.

The maximum value of PSD × f on the surface is about 100 nm.
If it is ² or less, it is easily confirmed that TOH is 4.5 nm or less in the glass substrate for information recording medium or the medium for hard disk. Further, in a hard disk drive or an information recording device manufactured using the same, since the surface shape of the glass substrate or the medium is maintained as it is, the TOH can be reduced.

In the present embodiment, the surface shape of the information recording medium is measured in a predetermined area using an optical interferometer or an AFM probe, and a PSD corresponding to a predetermined wavelength ν along the circumferential direction and the PSD are measured. The product PSD × f with the frequency f, which is the reciprocal of the predetermined wavelength ν, is calculated, and the maximum value is set to a predetermined value or less. For this reason, it is possible to eliminate the undulation component that hinders the flight of the head, and for example, it is possible to reduce the TOH to 4.5 nm or less. Further, it can be easily confirmed that the maximum value of PSD × f is equal to or less than a predetermined value.

Hereinafter, a first example of the inspection process in step S11 of FIG. 1 will be described in detail. In this example, a case where a circumferential texture is formed.

In the inspection step of step S11, the surface of the manufactured hard disk medium is 0.1 mm square to 5 mm.
Using a light interferometer (“ZygoNewview”, manufactured by Zygo), the surface shape in the vicinity of the circumferential texture in the area of mm square is adjusted to have a predetermined wavelength ν in the range of 0.1 along the circumferential direction.
Measure at ５5 mm and perform line analysis.

The reason why the predetermined area is set to be 0.1 mm square to 5 mm square is that when the visual field area of the optical interferometer uses an objective lens of 2.5 times, the zoom function of 0.5 times is used. This is because 2406 × 1796 μm ² , and 4390 × 3310 μm ² when the 1.0 × zoom function is used.

In the line analysis, a PSD corresponding to a predetermined wavelength ν as shown in FIG. 11 is calculated, and the PSD corresponding to the calculated predetermined wavelength ν and the frequency f which is the reciprocal of the predetermined wavelength ν are calculated. The product PSD × f is calculated (see FIG. 2). The maximum value of PSD × f on the medium surface is 1600 cm ²
Confirm the following and ship as a final product.

The maximum value of PSD × f on the medium surface is 1600
When the density is set to not more than cm ^2, the TOH of such a hard disk medium is inevitably 4.5 nm or less, so that good media characteristics can be provided. Preferably, the maximum value of PSD × f is 1300 cm ² or less. By doing so, the TOH of the hard disk medium can be set to 4.0 nm or less.

Hereinafter, a second example of the inspection process in step S11 of FIG. 1 will be described in detail.

In the inspection step of step S11, the surface of the manufactured hard disk medium is
The surface shape in the vicinity of the circumferential texture in the area of 0 μm square is measured along the circumferential direction using an optical interferometer at a predetermined wavelength ν range of 10 to 200 μm, and line analysis is performed.

The reason why the predetermined area is 10 μm square to 200 μm square is that the field of view of the optical interferometer is 62 × when a 50 × objective lens and a 2 × zoom function are used.
This is because it is 42 μm ² .

In the line analysis, a PSD corresponding to a predetermined wavelength ν as shown in FIG. 11 is calculated, and a product of the calculated PSD corresponding to the predetermined wavelength ν and a frequency f which is the reciprocal of the predetermined wavelength ν is calculated. Calculate PSD × f (see FIG. 2).

Then, it is confirmed that the maximum value of PSD × f on the medium surface is 1100 cm ² or less, and the medium is shipped as a final product.

The maximum value of PSD × f on the medium surface is 1100
When the density is set to not more than cm ² , the TOH of the hard disk is inevitably set to 4.5 nm or less, so that good media characteristics can be provided. Preferably, the maximum value of PSD × f of the hard disk is 900 cm ² or less. By doing so, the TOH of the hard disk medium can be set to 4.0 nm or less.

Hereinafter, a third example of the inspection process in step S11 of FIG. 1 will be described in detail.

In the inspection step of step S11, the surface of the manufactured hard disk medium is 1 μm square to 50 μm.
The surface shape in the vicinity of the circumferential texture in the area of m square is measured in the wavelength range of 1 to 50 μm using an AFM (scanning probe microscope “Nanoscope IV” manufactured by Beco (formerly Digital Instruments)). Perform line analysis along the direction.

The reason why the predetermined area is 1 μm square to 50 μm square is that the field of view of the AFM is 50 × 50 μm ² .

In the line analysis, a PSD corresponding to a predetermined wavelength ν as shown in FIG. 11 is calculated, and a product of the calculated PSD corresponding to the predetermined wavelength ν and a frequency f which is the reciprocal of the predetermined wavelength ν is calculated. Calculate PSD × f (see FIG. 2). Then, it is confirmed that the maximum value of PSD × f on the medium surface is 100 nm ² or less, and the medium is shipped as a final product.

The maximum value of PSD × f on the medium surface is 100 n
This is because, when it is set to m ² or less, the TOH of the hard disk is inevitably 4.5 nm or less, and good media characteristics can be provided. Preferably, the maximum value of PSD × f of the hard disk is set to 80 nm ² or less. By doing so, the TOH of the hard disk medium can be set to 4.0 nm or less.

According to the first to third examples of the inspection process, the surface shape of the circumferential texture in a predetermined area on the surface of the hard disk medium is determined by using an optical interferometer or an AFM.
And it can be easily confirmed that the maximum value of PSD × f is equal to or less than a predetermined value. Therefore, it is easy to inspect whether or not there is a swelling component which hinders the flight of the magnetic head.
H can be lowered.

In the line analysis in the first to third examples of the inspection process, PS (power spectrum) is extracted for a plurality of lines along the circumferential texture,
Preferably, the extracted results are averaged. Thereby, the line analysis can be performed more accurately. AFM
Then, for example, PS can be extracted for up to 1024 lines. In the optical interferometer, for example, line analysis can be performed on a three-dimensional image.

In the first to third examples of the inspection process, the line analysis is performed along the circumferential direction. However, the line analysis may be performed along the radial direction. In this case, it is preferable to consider both results obtained by line analysis performed along the circumferential direction and the radial direction.

For example, if the line analysis result obtained along the circumferential direction is suppressed to a low numerical value and the line analysis result obtained along the radial direction is set to a high numerical value, the On the other hand, since the surface shape of the information recording medium is appropriately roughened in the vertical direction, the resistance acting on the head flying while fluctuating can be reduced.

However, when the line analysis result obtained along the radial direction has an excessively high numerical value, it is considered that the surface shape of the information recording medium is likely to be worn by the head flying while fluctuating. Therefore, a numerical value as high as the time required for head crash becomes longer is most preferable.

In the first to third examples of the inspection process, the product PSD × f of the calculated PSD corresponding to the predetermined wavelength ν and the frequency f which is the reciprocal of the predetermined wavelength ν is used.
Is calculated, the baseline can be made horizontal. However, for two-dimensional measurement, the product PSD × f
^What is necessary is just to calculate ² .

The first to third examples of the inspection process are as follows:
Needless to say, this step can be executed after each step in the present manufacturing method is executed. However, this step may be executed before the film formation step in step S10 is executed.

In the above, the hard disk medium has been mainly described. However, the present invention is not limited to this.
It may be a magneto-optical disk, an optical disk, or the like.

[0167]

Embodiments of the present invention will be described below.

The present inventors carried out the following steps in accordance with the method of manufacturing the information recording medium shown in FIG. 1 to produce samples 1 to 19 and comparative examples 1 to 11 of the information recording medium.

Base Glass Selection Step (Step S1) As a base glass for a glass substrate for an information recording medium,
iO ₂ : 66.0: mol%, Al ₂ O ₃ : 11.0 mo
1%, Li ₂ O: 8.0 mol%, Na ₂ O: 9.0 mol
1%, MgO: 2.4 mol%, CaO: 3.6 mol
%, K ₂ O: 0.2 mol%, and SrO: 2.0 m
Aluminosilicate glass consisting of ol% was selected.

Sheet Glass Production Step (Step S2) A sheet glass having a uniform thickness was produced from the selected base glass for a glass substrate by a float method.

Work Extraction Step (Step S3) Sheet glass of aluminosilicate composition produced by the float method is cut simultaneously along an outer diameter of 96 mm and an inner diameter of 24 mm using a superalloy cutter. And a donut-shaped work with good concentricity was extracted.

End-Surface Polishing Step (Step S4) Next, grinding is performed in two steps using a grinding wheel having # 325 diamond and # 500 diamond abrasive adhered to the inner and outer peripheral end surfaces. Processing was performed, and the work was precisely adjusted to the product dimensions. At the same time as grinding this end face, also perform chamfering of the end face using a grinding wheel,
The specified glass substrate product dimensions were obtained. Next, grinding,
After the chamfering, the end face was polished using a slurry containing cerium oxide to smooth the chamfered face of the end face.

In the lapping process (step S5), the number is # 600, and the number is # 1000.
While supplying a slurry containing 65% by mass of alumina abrasive grains between the metal platen of the polishing machine and the information recording surface of the work, the upper surface and the lower surface of the work are simultaneously removed by the polishing machine.
A wrapping process consisting of stages was applied. Then, using water or a detergent, the frequency is about 48 kHz, and the output is 1 W / cm ^2.
The cleaning was performed while applying ultrasonic waves.

Primary Polishing Step (Step S6) Next, a lanthanoid oxide-based slurry containing cerium oxide and lanthanum oxide having an average particle diameter of 0.05 to 1.6 μm and a solid content of about 20% by mass. Was supplied to a polishing machine to perform primary polishing on the information recording surface of the work. Using a polishing machine in which a polishing pad made of urethane foam resin impregnated with cerium oxide is adhered to a surface that comes into contact with the work, 49 N is applied to the work through the polishing pad.
A load of about (5 kgf) was applied and the upper and lower surfaces of the work were simultaneously polished, and the polishing machine was operated until the work had a predetermined thickness.

Then, the frequency is adjusted by using water or detergent for the work.
Is about 48kHz, output is lW / cm ^TwoFrequency of ultrasound
While applying a cleaning treatment.

Precision Polishing Step (Step S7) The upper platen rotation speed and lower plate rotation speed are set so that the rotation speed of the carrier rotation is about 0.0166 / sec to 0.2833 / sec (1 to 17 rpm). The number of revolutions of the board was adjusted, and the upper and lower surfaces of the work were simultaneously subjected to precision polishing. When performing precision polishing, a suede type polishing pad was used. The nap layer in this suede type polishing pad has a 100% modulus range of 4900 to 2900.
It is a polishing member manufactured by melting and foaming a resin of 4500 kPa (50 to 250 kg / cm ² ), and then shaving the outermost surface to expose pores. lmm, the opening diameter of which is 30-100μ
m. The base layer of the suede type polishing pad is made of a resin sheet. Further, the maximum particle size is about 1 to 5 μm, the average particle size is 0.05 to 1.6 μm,
The content of the abrasive having a particle size of 1 to 5 μm is 0.1% of the total mass of the solid content.
A lanthanoid oxide slurry containing about 1 to 65% by mass of cerium oxide and lanthanum oxide as a main component, or a slurry containing finely divided silica was used.

Then, before stopping the precision polishing, the slurry was switched to water and rinsed, and the workpiece was put into pure water to apply pure water while applying ultrasonic waves having a frequency of about 48 kHz and an output of 1 W / cm ^2. Washing followed by a shower of pure water. Then, hydrofluoric acid kept at 40 ° C .: 0.01
The work is immersed for 1 minute in a buffered hydrofluoric acid aqueous solution bath, which is a mixture of 0.2% by mass and ammonium fluoride: 0.2% by mass, while applying ultrasonic waves having a frequency of about 48 kHz and an output of 1 W / cm ^2. And an etching process.

Thereafter, the work was placed in a commercially available alkaline aqueous solution of pH 11 (“RBS25” manufactured by Chemical Products Co., Ltd.) maintained at 40 ° C., and ultrasonic waves having a frequency of about 48 kHz and an output of 1 W / cm ² were applied. It was immersed for 1 minute while applying. This work is taken out of the alkaline aqueous solution bath, immersed in a pure water bath and rinsed, and finally, the work is rinsed in a pure water bath and ultrasonic waves having a frequency of about 48 kHz are applied in an isopropyl alcohol bath for 2 minutes. After immersion, it was dried in isopropyl alcohol vapor for 1 minute.

Chemical Strengthening Step (Step S8) Specifically, first, both are primary reagents and the ratio is 4: 6.
Consisting of potassium nitrate and sodium nitrate and 3
The work is immersed in the mixed molten salt kept at 80 ° C. for 3 hours, the surface layer of the work is subjected to chemical strengthening treatment by ion exchange, and the chemically strengthened work is gradually cooled, and then placed in a pure water bath. Soaked for hours.

Scrubbing Step (Step S9) The surface layer of the polycarbonate-based polyurethane resin cut into a strip shape is bonded with a double-sided tape so that the shape of the contact portion with the work is made into a strip shape. The urethane sponge for scrub wound spirally was prepared. In the circumferential direction of the work, the work is rotated while pinching the work at the inner peripheral edge provided in the commercially available scrub cleaning device, and the rotating work is held between two scrub urethane sponges for 10 seconds. The work surface was scrubbed. At this time, the rotation speed of the work is set to 5
/ Sec (300 rpm), the pressing pressure of the sponge is 39200
Pa (400 g / cm ² ) and a pH 11 aqueous potassium hydroxide solution were supplied at 30 ml / min between the work and the urethane sponge for scrubbing.

The workpiece was immersed in a pH 11 alkaline aqueous solution bath maintained at 40 ° C. for 1 minute while applying ultrasonic waves having a frequency of about 48 kHz and an output of 1 W / cm ² . The work was taken out of the alkaline aqueous solution bath, immersed in a pure water bath and rinsed to remove the alkaline aqueous solution. Finally, the work was rinsed in a pure water bath, immersed in an isopropyl alcohol bath for 2 minutes while applying ultrasonic waves at a frequency of 48 kHz, and then dried in isopropyl alcohol vapor for 1 minute to perform a drying treatment.

Film forming process (Step S10) A seed layer made of a NiAl alloy, an underlayer made of a CrMo alloy, a magnetic layer made of a CoCrPt alloy, and a C-based layer were formed on this information recording medium glass substrate by sputtering. A protective film was sequentially formed and a film forming process was performed. The magnetic layer was subjected to a circumferential texture treatment. Thereafter, a perfluoropolyether-based lubricant was applied using an immersion method, and a tape burnishing treatment was applied to the surface to produce a hard disk medium.

Inspection Step (Step S11) The surface shape in a predetermined area of the information recording surface of the manufactured information recording medium is measured by a probe of Nanoscope IV or ZygoNewview.
Was used to perform line analysis along the circumferential direction. In the line analysis, a product PSD × f of the PSD corresponding to the predetermined wavelength ν and the frequency f was calculated (see FIG. 2).

In the line analysis, the results of the line analysis performed on a plurality of lines are averaged, and the calculated PSD ×
From the maximum value of f, the presence or absence of a swelling component that hinders the flight of the head was evaluated. As a result of the evaluation, it was confirmed that the maximum value of PSD × f of the information recording medium was equal to or less than a predetermined value. TOH is 4.5 nm or less, more preferably 4.0 n
m or less of the information recording medium. The predetermined area and the predetermined value will be described later in second to fourth embodiments.

Hereinafter, samples 1 to 19 and comparative examples 1 to 11 of the information recording medium according to the first embodiment will be described.

In the inspection process executed in step S11 of FIG. 1, TOH [nm], fine scratch [presence / absence], and polishing spots [presence / absence] of the manufactured samples 1 to 19 and comparative examples 1 to 11 were obtained. No], and the size [nm] of the undulation was measured, and the relationship between the resin hardness [kPa (kg / cm ² )] and the maximum value of PSD × f [cm ² ] expressed in 100% modulus (Sample 1) ~ 7, Comparative Examples 1 ~
3) The rotation speed of the carrier rotation [/ sec (rp
m)] and the maximum value of PSD × f (cm ² ) (samples 8 to 12, comparative examples 4 to 6), and the maximum particle size of the abrasive [μm] and the maximum value of PSD × f [nm ^2] (Samples 13 to 19, Comparative Examples 7 to 11) and the like.

TOH [nm] reduces the gliding height of the head by gradually lowering the rotation speed of the information recording medium. At this time, a change in the piezo signal is detected by a piezo signal detecting device attached to the head. , Calculated from the rotation speed when the signal output sharply rises.

Table 1 shows the measurement results in the study.

[0189]

[Table 1]

[Sample 1] In the precision polishing step, 100% modulus was 7840 kPa (80 kg /
cm ² ) resin, a polishing machine having a carrier rotation speed of 0.1 / sec (6 rpm), an average particle size of 1 μm, a maximum particle size of 2 μm, and a particle size of 1 μm The above is 3% by mass of the solid content of the slurry.
A slurry solid containing cerium oxide as a main component was used. The information recording medium of Sample 1 manufactured by performing such a precision polishing process had no fine scratches, no uneven polishing, and had a TOH of 4.4 nm.

[Sample 2] In the precision polishing step, 100% modulus was 8820 kPa (90 kg /
cm ² ) except that a polishing member made of resin was used.
The same polisher and slurry solids as Sample 1 were used. The information recording medium of Sample 2 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and a TOH of 4.0 nm.

[Sample 3] In the precision polishing step, the 100% modulus was 9800 kPa (100 kg).
/ Cm ² ), except that a polishing member made of resin was used. The information recording medium of Sample 3 manufactured by executing such a precision polishing process had no fine scratches, no polishing unevenness, and TOH of 3.3 nm.

[Sample 4] In the precision polishing process, 100% modulus was 11760 kPa (120 kPa).
g / cm ² ) except that a polishing member made of a resin was used. The information recording medium of Sample 4 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and a TOH of 3.2 nm.

[Sample 5] In the precision polishing step, 100% modulus was 14700 kPa (150 kPa).
g / cm ² ) except that a polishing member made of a resin was used. The information recording medium of Sample 5 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and TOH of 3.4 nm.

[Sample 6] In the precision polishing step, 100% modulus was set to 19600 kPa (200 kPa).
g / cm ² ) except that a polishing member made of a resin was used. The information recording medium of Sample 6 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and a TOH of 3.5 nm.

[Sample 7] In the precision polishing step, the 100% modulus was 24500 kPa (250 kPa).
g / cm ² ) except that a polishing member made of a resin was used. The information recording medium of Sample 7 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and TOH of 4.0 nm.

[Sample 8] In the precision polishing step, 100% modulus was 12740 kPa (130 kPa).
g / cm ² ) resin, a polishing machine having a rotation speed of the carrier of 0.0333 / sec (2 rpm), an average particle diameter of 1 μm, a maximum particle diameter of 2 μm,
A slurry solid containing cerium oxide as a main component and having a particle diameter of 1 μm or more was 3% by mass of the slurry solid was used. The information recording medium of Sample 8 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and a TOH of 4.4 nm.

[Sample 9] In the precision polishing process, the rotation speed of the carrier was 0.05 / sec (3 rpm).
A polishing member made of the same resin as Sample 8 and a slurry solid content were used except that the polishing machine of m) was used. The information recording medium of Sample 9 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and a TOH of 4.0 nm.

[Sample 10] In the precision polishing step, the rotation speed of the carrier was 0.0666 / sec (4
A polishing member made of the same resin as that of Sample 8 and a slurry solid content were used except that a polishing machine (rpm) was used. The information recording medium of Sample 10 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and a TOH of 3.8 nm.

[Sample 11] In the precision polishing process, the rotation speed of the carrier was 0.15 / sec (9 rpm).
A polishing member made of the same resin as Sample 8 and a slurry solid content were used except that the polishing machine of m) was used. The information recording medium of Sample 11 manufactured by performing such a precision polishing process has no fine scratch,
There was no polishing unevenness, and TOH was 3.6 nm.

[Sample 12] In the precision polishing step, the rotation speed of the carrier was 0.25 / sec (15 rpm).
pm), except that a polishing member made of the same resin as in Sample 8 and a slurry solid content were used.
The information recording medium of Sample 12 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and TOH of 3.5 nm.

[Sample 13] In the precision polishing step, 100% modulus was 11760 kPa (120 kPa).
g / cm ² ) resin, a polishing machine having a carrier rotation speed of 0.1 / sec (6 rpm), an average particle size of 0.1 μm, and a maximum particle size of 1.1 μm
In addition, a slurry solid containing cerium oxide as a main component and having a particle size of 1 μm or more was 0.1% by mass of the slurry solid was used. The information recording medium of Sample 13 manufactured by performing such a precision polishing process has no fine scratches, no polishing unevenness, and has a TOH of 3.
It was 4 nm.

[Sample 14] In the precision polishing step, a sample having an average particle size of 1 μm, a maximum particle size of 1.9 μm, and a particle size of 1 μm or more accounted for 3% by mass of the solid content of the slurry.
A polishing member and a polishing machine made of the same resin as Sample 13 were used except that a slurry solid containing cerium oxide as a main component was used. The information recording medium of Sample 14 manufactured by performing such a precision polishing process has no fine scratches, no polishing unevenness, and a TO
H was 3.5 nm.

[Sample 15] In the precision polishing step, the average particle size was 0.5 μm and the maximum particle size was 1.5 μm.
With a particle size of 1 μm or more
A polishing member and a polishing machine made of the same resin as in Sample 13 were used except that a slurry solid content containing cerium oxide as a main component, which was a mass%, was used. The information recording medium of Sample 15 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and a TOH of 3.8 nm.

[Sample 16] In the precision polishing step, the 100% modulus was set to 19600 kPa (200 kPa).
g / cm ² ) of a resin, a polishing machine having a carrier rotation speed of 0.25 / sec (15 rpm), an average particle size of 0.1 μm, and a maximum particle size of 1.1.
A slurry solid containing cerium oxide as a main component and having a particle size of 1 μm or more and having a particle size of 1 μm or more was 0.1% by mass of the slurry solid. The information recording medium of the sample 16 manufactured by performing such a precision polishing process includes:
There was no fine scratch, no polishing unevenness, and TOH was 3.6 nm.

[Sample 17] In the precision polishing step, the average particle size was 0.03 μm and the maximum particle size was 0.1 μm.
A polishing member and a polishing machine made of the same resin as Sample 16 were used except that a slurry solid containing silica as a main component not containing particles having a particle size of 1 μm or more was used. The information recording medium of Sample 17 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and had a TOH of 3.3 nm.

[Sample 18] In the precision polishing step, the average particle size was 0.1 μm and the maximum particle size was 0.15 μm.
A polishing member and a polishing machine made of the same resin as Sample 16 were used except that a slurry solid containing silica as a main component not containing particles having a particle size of 1 μm or more was used. The information recording medium of Sample 18 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and TOH of 3.3 nm.

[Sample 19] In the precision polishing step, 100% modulus was 12740 kPa (130 kPa).
g / cm ² ) resin, a polishing machine having a carrier rotation speed of 0.2 / sec (12 rpm),
And the average particle size is 0.5 μm and the maximum particle size is 2.5 μm
And having a particle size of 1 μm or more is 1% of the solid content of the slurry.
A slurry solid content of 8% by mass containing cerium oxide as a main component was used. The information recording medium of Sample 19 manufactured by performing such a precision polishing process has no fine scratches, no polishing unevenness, and a TOH of 3.8 n.
m.

[Comparative Example 1] In the precision polishing process,
100% Modulus is 4900 kPa (50 kg / cm
² ) a polishing member made of the resin, a polishing machine having a carrier rotation speed of 0.05 / sec (3 rpm), an average particle diameter of 1 μm, a maximum particle diameter of 2 μm, and a particle diameter of 1 μm.
A slurry solid containing cerium oxide as a main component and having a size of 3 μm or more was 3% by mass of the slurry solid was used.
The information recording medium of Comparative Example 1 manufactured by performing such a precision polishing step had no fine scratches, no polishing unevenness, and a TOH of 6.2 nm.

[Comparative Example 2] In the precision polishing step,
The 100% modulus is 5880 kPa (60 kg / cm
^The same polishing machine and the same slurry solid content as those of Comparative Example 1 were used except that a polishing member made of the resin of ² ) was used. Comparative Example 2 manufactured by performing such a precision polishing process
No. information recording medium had no fine scratches, no polishing unevenness, and had a TOH of 5.9 nm.

[Comparative Example 3] In the precision polishing step,
The 100% modulus is 6860 kPa (70 kg / cm
^The same polishing machine and the same slurry solid content as those of Comparative Example 1 were used except that a polishing member made of the resin of ² ) was used. Comparative Example 3 manufactured by performing such a precision polishing process
No. information recording medium had no fine scratches, no polishing unevenness, and had a TOH of 5.1 nm.

[Comparative Example 4] In the precision polishing process,
100% modulus is 7840 kPa (80 kg / cm
² ) A polishing member made of the resin, a polishing machine having a carrier rotation speed of 0.0166 / sec (1 rpm), an average particle size of 1 μm, a maximum particle size of 2 μm, and a particle size of 1 μm or more Is a slurry solid content containing cerium oxide as a main component, which is 3% by mass of the slurry solid content. The information recording medium of Comparative Example 4 manufactured by performing such a precision polishing process had fine scratches, no polishing unevenness, and a TOH of 5.5 nm.

[Comparative Example 5] In the precision polishing step,
The rotation speed of the carrier rotation is 0.2833 / sec (17r
pm), except that a polishing member made of the same resin as in Comparative Example 4 and a slurry solid content were used. The information recording medium of Comparative Example 5 manufactured by performing such a precision polishing process had fine scratches, no polishing unevenness, and TOH of 5.0 nm.

[Comparative Example 6] In the precision polishing step,
The rotation speed of the carrier rotation is 0.333 / sec (20 rpm).
A polishing member and a slurry solid made of the same resin as in Comparative Example 4 were used except that the polishing machine of m) was used. Comparative Example 6 manufactured by performing such a precision polishing process
The information recording medium No. had no fine scratches, had uneven polishing, and had a TOH of 5.1 nm.

[Comparative Example 7] In the precision polishing step,
100% modulus is 7840 kPa (80 kg / cm
² ) a polishing member made of the resin, a polishing machine having a carrier rotation speed of 0.0333 / sec (2 rpm), an average particle size of 0.05 μm, a maximum particle size of 1 μm, and a particle size of A slurry solid containing cerium oxide as a main component and having a particle size of 1 μm or more was 0.1% by mass of the slurry solid was used. The information recording medium of Comparative Example 7 manufactured by performing such a precision polishing process had no fine scratches, no uneven polishing, and had a TOH of 5.5 nm.

[Comparative Example 8] In the precision polishing step,
The rotation speed of carrier rotation is 0.15 / sec (9 rpm)
A polisher having an average particle size of 1.5 μm, a maximum particle size of 5 μm, and a particle size of 1 μm or more is 65 mass% of the slurry solid content, and a slurry solid containing cerium oxide as a main component. A polishing member made of the same resin as that of Comparative Example 7 was used except that the amount of the abrasive was used. The information recording medium of Comparative Example 8 manufactured by performing such a precision polishing process is:
There was no fine scratch, there was a polishing unevenness, and TOH was 5.7 nm.

[Comparative Example 9] In the precision polishing step,
The 100% modulus is 11760 kPa (120 kg /
polishing member made of resin cm ^2), the polishing machine rotating speed of 0.1 / sec rotation of the carrier (6 rpm), and the average particle size is at 1.6 [mu] m, maximum particle size at 3.3 [mu] m, and A slurry solid having cerium oxide as a main component and having a particle size of 1 μm or more was 40% by mass of the slurry solid. The information recording medium of Comparative Example 9 manufactured by performing such a precision polishing process had no fine scratches, no polishing unevenness, and TOH was 4.9 nm.

Comparative Example 10 In the precision polishing step, the average particle size was 0.5 μm and the maximum particle size was 3.2 μm.
Having a particle size of 1 μm or more
An abrasive member and an abrasive made of the same resin as in Comparative Example 9 were used, except that a slurry solid content of cerium oxide as a main component, which was 2% by mass, was used. The information recording medium of Comparative Example 10 manufactured by performing such a precision polishing process has fine scratches, no polishing unevenness,
OH was 4.8 nm.

[Comparative Example 11] In the precision polishing step, 100% modulus was 7840 kPa (80 kg /
a polishing member made of a resin of ² cm ² ), a polishing machine having a rotation speed of rotation of the carrier of 0.0666 / sec (4 rpm),
And an average particle size of 0.5 μm and a maximum particle size of 3.1 μm
And having a particle size of 1 μm or more is one of the slurry solid content.
A slurry solid content of 8% by mass containing cerium oxide as a main component was used. The information recording medium of Comparative Example 11 manufactured by performing such a precision polishing process has no fine scratches, no polishing unevenness, and a TOH of 5.3 nm.
was.

According to Samples 1 to 7 and Comparative Examples 1 to 3, as shown in Tables 1 and 2 and FIG. 3, the resin hardness represented by 100% modulus was expressed as [kPa (kg / c
m ² )] and the maximum value of PSD × f [cm ² ],
In order for the maximum value of PSD × f corresponding to TOH of 4.5 nm or less to be 1600 cm ² or less, the 100% modulus of the resin should be 7840 to 24500 kPa.
(80 to 250 kg / cm ² ). More preferably, the 100% modulus of the resin is 9800 to 19600 kPa (100 to 200 kg).
/ Cm ² ), it was found that the maximum value of PSD × f corresponding to TOH of 3.5 nm or less can be 900 cm ² or less.

The reason for this is that the larger the 100% modulus, the more difficult the surface layer of the nap layer is to be deformed, and the ratio of the amorphous portion and the ratio of the crystal portion in the molecular structure of the molecules forming the resin are increased. It is considered that because the surface layer of the layer becomes hard in a microscopic structure, it is possible to remove undulation components on the information recording surface of the work.

On the other hand, it is considered that if the 100% modulus of the resin is too large, it is difficult to mold the foam uniformly and flatly, and fine scratches are likely to occur. That is, the 100% modulus is 9800 to 19600 kPa (100 to 200 kg).
/ Cm ² ), the microscopic hardness of the surface layer of the nap layer is sufficiently large and the homogeneity is high, so that it is possible to remove the undulations most.

According to Samples 8 to 12 and Comparative Examples 4 to 6, as shown in Tables 1 and 3 and FIG. 4, the rotation speed [/ sec (rpm)] of the rotation of the carrier and the maximum value of PSD × f were obtained. From the relationship with [cm ² ], in order for the maximum value of PSD × f corresponding to TOH of 4.5 nm or less to be 1100 cm ² or less, the rotation speed of the carrier rotation is 0.0333 / sec. 0.25 / sec (2 rpm to 15 rpm
m).

This is because the rotation speed of the carrier rotation is 0.0
When the rate is less than 333 / sec (2 rpm), the time required for the polishing pad to perform precision polishing on the work in a certain direction becomes relatively long, and undulation components having a wavelength of 10 to 50 μm are easily generated. Conceivable. When the rotation speed of the carrier exceeds 0.25 / sec (15 rpm), the load on the polishing machine and the carrier increases,
The carrier does not rotate smoothly. Therefore, it is considered that undulation components and fine scratches occurred on the surface of the work.

Samples 13 to 19 and Comparative Examples 7 to 11
According to Table 1, as shown in Tables 1 and 4 and FIG. 5, from the relationship between the maximum particle size [μm] of the abrasive and the maximum value [nm ² ] of PSD × f, TOH is equivalent to 4.5 nm or less. PSD
It has been found that the maximum particle size of the abrasive should be about 2.5 μm or less in order to make the maximum value of × f 100 nm ² or less. Thereby, the undulation component can be reduced and the occurrence of polishing unevenness, fine scratches, and the like can be prevented.

Further, as shown in Tables 1 and 4 and FIG. 6, the ratio [mass%] of the abrasive having a particle size of 1 μm or more in the slurry solid content to the maximum value of PSD × f [nm ² ] was determined. From the relationship, PSD corresponding to TOH of 4.5 nm or less
In order to make the maximum value of xf equal to or less than 100 nm ² , it was found that the abrasive having a particle size of about 1 to 2.5 μm should be about 10% of the total mass of the slurry solids. . Thereby, the undulation component can be reduced.

Further, according to Samples 17 to 19 and Comparative Example 7, as shown in Table 1, when a slurry containing finely divided silica was used, the average particle size and the maximum particle size of silica were small. Also, since there was no polishing unevenness, it was found that aggregation did not occur.

Hereinafter, a second embodiment will be described.

In the inspection process executed in step S11 of FIG. 1, the circle of the information recording medium samples (samples 1 to 7 and comparative examples 1 to 3) of 0.1 mm square to 5 mm square in the first embodiment was used. The surface shape in the vicinity of the circumferential texture was measured along the circumferential direction using ZygoNewview in a range of a predetermined wavelength ν of 0.1 to 5 mm, and the average undulation Wa was measured.
[Nm] and the average undulation Wa [nm] of the sample.
And the relationship between TOH [nm] and the maximum value of PSD × f [cm ² ] and TOH [nm] were studied. In the line analysis, measurement was performed using a probe along the circumferential texture, PS (power spectrum) was extracted for 1024 lines, and the extracted results were averaged.

Hereinafter, the measured results are shown in Table 2 and FIG.

[0231]

[Table 2]

From the measured results, no correlation could be found from the relationship between the average swell Wa [nm] and TOH [nm] shown in FIG. 7 (a). From the relationship between the maximum value of PSD × f [cm ² ] and TOH [nm] shown in FIG. 7B, it was found that their correlation was proportional.

According to the second embodiment, since the correlation between the maximum value [cm ² ] of PSD × f and TOH [nm] is proportional, excellent media characteristics with TOH of 4.5 nm or less are obtained. It has been found that the maximum value of PSD × f should be 1600 cm ² or less in order to use the information recording medium. More preferably, when the maximum value of PSD × f is a value of 1300 cm ² or less, TOH is 4.0 nm.
It has been found that an information recording medium having the following superior media characteristics can be obtained.

Hereinafter, a third embodiment will be described.

In the inspection process performed in step S11 of FIG. 1, the samples 8 to 12 of the information recording medium according to the first embodiment and the 10 μm square to 200 μm of the comparative examples 4 to 6 were used.
The surface shape near the circumferential texture in μm square
Using ZygoNewview, a predetermined wavelength ν along the circumferential direction
Is measured in the range of 10 to 200 μm, and the average undulation Wa
[Nm] and the average undulation Wa [nm] of the sample.
And the relationship between TOH [nm] and the maximum value of PSD × f [cm ² ] and TOH [nm] were studied. In the line analysis, measurement was performed using a probe along the circumferential texture, PS (power spectrum) was extracted for 256 lines, and the extracted results were averaged.

The measured results are shown in Table 3 and FIG.

[0237]

[Table 3]

From the measured results, no correlation could be found from the relationship between the average undulation Wa [nm] and the TOH [nm] shown in FIG. 8 (a). From the relationship between the maximum value of PSD × f [cm ² ] and TOH [nm] shown in FIG. 8B, it was found that their correlation was proportional.

According to the third embodiment, since the correlation between the maximum value [cm ² ] of PSD × f and TOH [nm] is proportional, excellent media characteristics with TOH of 4.5 nm or less are obtained. It has been found that the maximum value of PSD × f may be set to a value of 1100 cm ² or less in order to use the information recording medium. More preferably, when the maximum value of PSD × f was 900 cm ² or less, it was found that an information recording medium having TOH of 4.0 nm or less and having more excellent media characteristics could be obtained.

Hereinafter, a fourth embodiment will be described.

In the inspection process executed in step S11 of FIG. 1, the samples 13 to 19 of the information recording medium according to the first embodiment and the 1 μm square to 50 μm of the comparative examples 7 to 11 were obtained.
The surface shape near the circumferential texture in μm square
Using a probe of Nanoscope IV, the range of the predetermined wavelength ν is measured along the circumferential direction at 1 to 50 μm, and the average roughness Ra
[Nm] was measured, and the relationship between the average roughness Ra [nm] of the sample and TOH [nm] and the relationship between the maximum value of PSD × f [nm ² ] and TOH [nm] were studied.

The measured results are shown in Table 4 and FIG.

[0243]

[Table 4]

From the measured results, no correlation could be found from the relationship between the average roughness Ra [nm] and TOH [nm] shown in FIG. 9 (a). On the other hand, from the relationship between the maximum value [nm ² ] of PSD × f and TOH [nm] shown in FIG. 9B, it was found that their correlation was proportional.

According to the fourth embodiment, since the correlation between the maximum value [nm ² ] of PSD × f and TOH [nm] is proportional, excellent media characteristics with TOH of 4.5 nm or less are obtained. It has been found that the maximum value of PSD × f should be set to a value of 100 nm ² or less in order to use the information recording medium. More preferably, the maximum value of PSD × f is set to 8
It was found that when the value was 0 nm ² or less, an information recording medium having TOH of 4.0 nm or less and having more excellent media characteristics could be obtained.

In the second to fourth embodiments, the PSD
It is considered that the reason why the TOH decreases when the maximum value of xf decreases is that there is an effect of reducing obstacles in the head flight direction. On the other hand, Wa and Ra and TOH, which are averaged values,
The reason why no correlation can be found in the relationship with
It is considered that a and Ra include components other than the head flight direction.

[0247]

As described above in detail, according to the information recording medium of the first embodiment of the present invention and the glass substrate for the information recording medium of the third embodiment, the power spectral density corresponding to a predetermined wavelength is obtained. Since the product of the predetermined wavelength and the reciprocal of the predetermined wavelength is equal to or less than a predetermined value, a medium or a glass substrate having a low TOH can be provided.

According to the surface inspection method described above,
Inspection of TOH can be easily performed without touching the surface.

According to the method of manufacturing a glass substrate for an information recording medium according to the second embodiment of the present invention, the surface of the glass substrate is made to have a 100% modulus of 7840 to 24500 k.
By polishing with a polishing member manufactured by processing a resin of Pa, a glass substrate for an information recording medium having excellent media characteristics can be manufactured.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing an information recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a measured wavelength ν and PSD × f.

FIG. 3 Resin hardness (100% modulus) and PSD × f
FIG. 6 is a diagram showing a relationship between the maximum value and the maximum value.

FIG. 4 is a diagram showing the relationship between the rotation speed of the carrier and the maximum value of PSD × f.

FIG. 5 is a diagram showing the relationship between the maximum particle size of the abrasive and the maximum value of PSD × f.

FIG. 6 is a diagram showing a relationship between a ratio of an abrasive having a particle diameter of 1 μm or more in a slurry solid content and a maximum value of PSD × f.

FIGS. 7A and 7B are diagrams showing a relationship between an index of undulation and TOH when measured in a wavelength range of 0.1 to 5 mm using an optical interferometer, and FIG. TOH
(B) shows the relationship between the maximum value [cm ² ] of PSD × f and TOH [nm].

FIG. 8 is a diagram showing the relationship between the index of swelling and TOH when measured in a wavelength range of 10 to 200 μm using an optical interferometer, and (a) shows the mean swelling Wa [nm] and TO
H (nm), and (b) shows the relationship between PSD × f maximum value [cm ² ] and TOH [nm].

FIG. 9: 1 to 50 μm with a probe using an atomic force microscope
5A and 5B are diagrams showing a relationship between an index of undulation and TOH when measured in a wavelength range of (a), (a) shows a relationship between average roughness Ra [nm] and TOH [nm], and (b) shows a PSD. × f
Shows the relationship between the maximum value [nm ² ] and TOH [nm].

FIG. 10 is a process chart showing a conventional method for manufacturing an information recording medium.

FIG. 11 is a diagram showing a relationship between measured wavelength ν and PSD.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G11B 5/84 G11B 5/84 A F term (reference) 3C058 AA07 AA09 CA01 CA06 CB01 CB10 5D006 BB07 CB04 CB07 DA03 5D112 AA02 AA05 AA24 BA03 GA11 GA14 JJ03

Claims (22)

[Claims] 1. An information recording medium having a recording layer formed on a substrate, wherein at least one recording layer is formed on the substrate, wherein the surface shape of the recording layer is a predetermined area on the surface. 2. The information recording medium according to claim 1, wherein a maximum value of a product of a power spectral density measured at a predetermined wavelength and a reciprocal of the predetermined wavelength is equal to or less than a predetermined value. 2. The measurement according to claim 1, wherein the measurement is performed using an optical interferometer, and when the area of the predetermined region is 0.1 mm square to 5 mm square, the predetermined value is 1600 cm ² or less. Information recording medium. 3. The information recording medium according to claim ^2, wherein the predetermined value is 1300 cm ² or less. 4. The area of the predetermined region is 10 μm square to 2 μm.
When the square is 00 μm, the predetermined value is 1100c
^2. The information recording medium according to claim 1, which has a value of m2 or less. 5. The information recording medium according to claim 4, wherein said predetermined value is 900 cm ² or less. 6. The measurement is performed by scanning with a probe of an atomic force microscope, and the area of the predetermined region is 1 μm.
When the square is 50 μm square, the predetermined value is 10
The information recording medium according to any one of claims 1 to 7 is 0 nm ² or less. 7. The information recording medium according to claim 6, wherein the predetermined value is 80 nm ² or less. 8. The recording layer or the main surface of the substrate,
The information recording medium according to claim 1, wherein a circumferential texture is formed. 9. A method for manufacturing a glass substrate for an information recording medium in which a recording layer is formed on a substrate, wherein the surface of the glass substrate has 784% 100% modulus.
A method for producing a glass substrate for an information recording medium, comprising a step of polishing a resin having a pressure of 0 to 24500 kPa with a polishing member. 10. The polishing member is set at 0.0333 / sec.
The method for producing a glass substrate for an information recording medium according to claim 9, wherein the glass substrate is rotated at a rotation speed of 0.25 / sec. 11. In the polishing step, the maximum particle size is 1 to 3.
10. A slurry containing an abrasive having a size of μm is used.
The method for producing a glass substrate for an information recording medium according to the above. 12. In the polishing step, the maximum particle size is 1 to 3.
10. The method for producing a glass substrate for an information recording medium according to claim 9, wherein a slurry containing an abrasive whose μm is 10% or less of the mass of the solid content of the slurry is used. 13. The polishing step, wherein the particle diameter is 0.01 to
The method for producing a glass substrate for an information recording medium according to claim 9, wherein a slurry containing 1 µm of silica is used. 14. The method for manufacturing a glass substrate for an information recording medium according to claim 9, wherein the polishing member is formed by processing a resin having a 100% modulus of 9800 to 19600 kPa. 15. A glass substrate for an information recording medium manufactured by the method for manufacturing a glass substrate for an information recording medium according to any one of claims 9 to 14, wherein the surface shape of the substrate is the same as that of the surface. A glass substrate for an information recording medium, wherein a maximum value of a product of a power spectrum density measured at a predetermined wavelength and a reciprocal of the predetermined wavelength in a predetermined region is set to a predetermined value or less. 16. The measurement is performed using an optical interferometer,
16. The glass substrate for an information recording medium according to claim 15, wherein the predetermined value is 1600 cm ² or less when the area of the predetermined region is 0.1 mm square to 5 mm square. 17. The glass substrate for an information recording medium according to claim 16, wherein the predetermined value is 1300 cm ² or less. 18. The area of the predetermined region is 10 μm square or less.
When the area is 200 μm square, the predetermined value is 1100
16. The glass substrate for an information recording medium according to claim 15, which has a size of not more than cm ² . 19. The glass substrate for an information recording medium according to claim 18, wherein the predetermined value is 900 cm ² or less. 20. The measurement is performed by scanning with a probe of an atomic force microscope, and the area of the predetermined region is 1 μm.
When the square is from m square to 50 μm square, the predetermined value is 1
The glass substrate for an information recording medium according to claim 15, which has a thickness of 00 nm ² or less. 21. The glass substrate for an information recording medium according to claim 20, wherein the predetermined value is 80 nm ² or less. 22. The method according to claim 15, wherein a circumferential texture is formed on a main surface of the substrate.
Item 10. A glass substrate for an information recording medium according to item 9.