JP3497488B2 - Method for manufacturing substrate for information recording medium, and method for manufacturing information recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium used as a recording medium for information processing equipment and a method for manufacturing a substrate thereof.

[0002]

2. Description of the Related Art A magnetic disk is one of the information recording media used as a recording medium for information processing equipment. The magnetic disk is formed by forming a thin film such as a magnetic layer on a substrate. Recently, in response to the demand for higher recording density, the flying distance between the magnetic disk and the magnetic head is, for example, three.
It is very small, less than 0 nm.
Substrates with high flatness and high smoothness are required. By selecting the polishing pad used in the polishing step and reducing the particle size of the polishing abrasive grains, a highly flat and highly smooth substrate surface can be obtained. On the other hand, not only high flatness and high smoothness of the substrate, but also for the magnetic head, a magnetoresistive head (MR head) using an anisotropic magnetoresistive effect from a thin film head,
It has been changed to a giant magnetoresistive head (GMR head), and is responding to higher recording density.

[0003]

As described above, in order to reduce the flying height of the magnetic head necessary for increasing the recording density,
High flatness of the magnetic disk surface is essential,
In addition, when an MR head is used, high flatness and high smoothness are required on the surface of the magnetic disk due to the problem of thermal asperity. In this thermal asperity, when there is a protrusion on the surface of the magnetic disk, the MR head is affected by this protrusion and heat is generated in the MR head, and this heat changes the resistance value of the head, causing electromagnetic conversion malfunction. It is a phenomenon that causes it. As described above, demands for high flatness and high smoothness of the magnetic disk surface are increasing day by day in order to reduce the flying height of the magnetic head and prevent the occurrence of thermal asperity. However, the high-precision polishing of the substrate surface has reached the stage where the high recording density of the magnetic disk cannot be realized. That is, no matter how highly precise polishing is performed, high flatness and high smoothness cannot be obtained if convex portions due to foreign matter or the like are subsequently formed on the substrate.
Needless to say, the protrusions due to foreign substances have been removed from the past, but the protrusions on the substrate, which were conventionally allowed, are now regarded as a problem at the high recording density level. When thin films such as magnetic layers are stacked with these types of protrusions attached to the surface of the substrate, protrusions are formed on the surface of the magnetic disk, reducing the flying height of the magnetic head and preventing thermal asperity (during recording / playback). Error prevention). Similarly, when thin films such as recording layers are stacked with the protrusions of this type adhered to the surface of the substrate, they cause defects such as errors during recording / reproduction of the information recording medium.

According to the present invention, it is possible to suppress and prevent the formation of a convex portion on the substrate, which is an obstructive factor for lowering the flying height of the magnetic head and preventing thermal asperity and a defect factor of the information recording medium. The purpose is to

[0005]

The inventors of the present invention sometimes have a convex portion that cannot be completely reduced even if the substrate is washed and dried. The magnetic layer in the state where the convex portion adheres to the substrate surface is present. It has been found that when thin films such as the above are laminated, a convex portion is formed on the surface of the magnetic disk, which hinders lowering of the flying height of the magnetic head and prevention of thermal asperity. Then, this convex portion is C existing in the cleaning liquid or the atmosphere,
It was found to contain at least one of O, Al, Si, Fe, Cu, Zn, and Zr. The inventors of the present invention have made a thorough investigation into the cause of the protrusions containing these elements adhering to the substrate.When the substrate surface is washed with water or dried after rinsing, the water attached on the substrate remains dry. It was found that a convex portion was formed in the trace. Further, it has been found that some of the convex portions containing these elements cannot be removed by various cleanings, and in that case, they cannot be removed without re-polishing the substrate. As the water used in the substrate washing / drying process, water that has been filtered or DI water (deionized water) is generally used. The washing / drying step is performed in a clean atmosphere such as a clean room or in the air. In these water and atmosphere, C, O, Al, Si, SiO ₂ , SiOH, Fe,
Although Cu, Zn, Zr, etc. are contained, the water containing these elements is combined with the condition of the surface state (hydrophobicity) of the substrate surface, and remains in a specific region to form a convex portion. It has been found. Furthermore, as a result of diligent investigation of the method of generating the convex portion, it was found that the size (height) of the convex portion is very closely related to the wettability of the substrate surface before cleaning. Specifically, the wettability of the substrate surface before cleaning is poor (hydrophobic)
Since the water droplets of the cleaning water stay on the surface of the substrate and are dried as they are, the water or an element contained in the atmosphere gathers in a specific region to form a convex portion. On the other hand, if the wettability of the substrate surface before cleaning is good (hydrophilic), the water droplets of the cleaning water spread and dry on the substrate surface, so that the above elements contained in water or the atmosphere do not collect in a specific region. It was found that since the particles were dispersed, no convex part was formed, or only a convex part having a height that did not affect the head crush and the thermal asperity was formed. The contact angle of water is generally used as an index of the surface condition (wettability) of the substrate, but the contact angle of water on the substrate surface before the cleaning / drying process is 2
It has been found that the above convex portions are easily formed when the angle exceeds 0 °. Then, the contact angle of water on the substrate surface before the cleaning / drying step in the manufacturing process of the information recording medium substrate, and C, O, Al as main components adhered to the substrate surface obtained through the cleaning / drying step, The correlation of the size (height) of the convex portion including at least one of Si, Fe, Cu, Zn, and Zr is obtained in advance, and the size of the convex portion that does not cause a product defect based on this correlation. Height (height),
It was found that product defects can be avoided by controlling the contact angle of water on the substrate surface before the cleaning / drying process. The wettability of the substrate surface is related to the surface condition of the substrate surface,
Generally expressed as the contact angle of water. The contact angle of water is usually measured by a measuring method called a liquid method. The surface condition of the substrate surface (wettability, contact angle of water), the processing method when manufacturing the substrate (such as cleaning and drying process), the environment when manufacturing and inspecting the substrate, the packaging condition of the substrate, the packaging of the substrate Storage environment of the substrate such as the type of packaging bag (gas released from the packaging bag, number of particles generated from the packaging bag, etc.), storage period of the substrate, surface roughness of the substrate surface, substrate material, surface of the substrate It changes depending on the treatment (for example, hydrophilic treatment), and these complex elements are entangled to determine the wettability of the substrate surface. Therefore, it was found that it is necessary to control the contact angle of water on the surface of the substrate before the cleaning / drying process by controlling not only the cleaning / drying process but also these complex elements, thereby completing the present invention. Came to.

The present invention has the following configuration.

(Structure 1) In a method for manufacturing an information recording medium substrate having a cleaning / drying step of cleaning / drying a precision-polished substrate for information recording medium, contact of water on the surface of the substrate before the cleaning / drying step The correlation between the corner and the size (height) of the convex portion attached to the surface of the substrate obtained through the cleaning / drying step is obtained, and the convex portion forms at least a recording layer on the substrate to obtain information. A recording medium, and a slider (recording and / or reproducing element) having a size (height) that does not cause a hit when the slider is run on the surface of the medium, and / or recording and / or reproducing A method for manufacturing a substrate for information recording medium, which comprises controlling the contact angle of water on the substrate surface before the cleaning / drying process so that the size (height) does not cause an error when performing .

(Structure 2) In a method for manufacturing an information recording medium substrate having a cleaning / drying step of cleaning / drying a precision-polished information recording medium substrate, contact of water on the substrate surface before the cleaning / drying step An angle and at least a recording layer is formed on the substrate to form an information recording medium, and a slider provided with a recording and / or reproducing element is further run on the medium surface to obtain a glide yield (glide test pass (pass). )
Rate, glide yield), and the error occurrence rate when recording and / or reproducing are performed, and the contact angle of water on the substrate surface is a glide defect (glide test fails), and recording. And / or a method of manufacturing a substrate for an information recording medium, wherein an error when reproducing is set to a value that does not occur.

(Structure 3) The method for manufacturing a substrate for an information recording medium according to Structure 1 or 2, wherein the contact angle of water on the surface of the substrate before the cleaning / drying step is 20 ° or less.

(Structure 4) In a method of manufacturing an information recording medium substrate having a step of packaging an information recording medium substrate obtained through a washing / drying step, at least the packaging is released to form a film on the substrate. The method for producing a substrate for an information recording medium, wherein the contact angle of water on the surface of the substrate immediately before pre-cleaning and drying is set to 20 ° or less.

(Structure 5) The contact angle of water on the surface of the substrate from immediately after the washing / drying step to immediately before the step of pre-cleaning and drying before unpacking and forming a film on the substrate. Is maintained at 20 ° or less
A method for manufacturing the information recording medium substrate described.

(Structure 6) The method for manufacturing a substrate for an information recording medium according to any one of structures 1 to 5, wherein the substrate is a glass substrate.

(Structure 7) The method for manufacturing an information recording medium substrate according to any one of structures 1 to 6, wherein the information recording medium substrate is a magnetic disk substrate.

(Structure 8) A step of preparing a substrate for an information recording medium that has been precisely polished, a step of washing and drying before forming a film on the substrate, and a step of at least a recording layer on the washed and dried substrate. In the method for manufacturing an information recording medium having a step of forming a contact angle of water on the surface of the substrate before the cleaning, and a convex portion attached to the surface of the substrate obtained through the step of cleaning and drying. By determining the correlation with the size (height), the convex portion forms at least a recording layer on the substrate to form an information recording medium, and further, a slider provided with a recording and / or reproducing element is provided on the medium surface. So that the size (height) does not cause a hit when running to
And / or controlling the contact angle of water on the surface of the substrate before the cleaning so that the size (height) does not cause an error when recording and / or reproducing. Method of manufacturing information recording medium.

(Structure 9) A step of preparing a precision-polished substrate for an information recording medium, a step of washing and drying before forming a film on the substrate, and a step of at least a recording layer on the washed and dried substrate And a contact angle of water on the surface of the substrate before the cleaning, and at least a recording layer is formed on the substrate to form an information recording medium. And / or a glide yield (glide test pass (pass) rate, glide yield) when a slider equipped with a reproducing element is run on the surface of the medium, and an error occurrence rate when recording and / or reproducing are performed. , And the contact angle of water on the surface of the substrate is a value that does not cause defective glide (failed glide test) and error during recording and / or reproduction. Method of manufacturing an information recording medium according to.

(Structure 10) The method for manufacturing an information recording medium according to Structure 8 or 9, wherein the contact angle of water on the surface of the substrate before the cleaning is controlled to be 20 ° or less.

(Structure 11) The method for manufacturing an information recording medium according to any one of structures 8 to 10, wherein the step of cleaning and drying is accompanied by spin dry drying.

(Structure 12) The method for manufacturing an information recording medium according to any one of structures 8 to 11, wherein the substrate is a glass substrate.

(Structure 13) The method for manufacturing an information recording medium according to any one of structures 8 to 12, wherein the information recording medium is a magnetic disk.

[0020]

According to the structure 1, C, O, Al, Si, Fe,
To make the contact angle of water on the substrate surface before the cleaning / drying process (particularly before the drying process) that causes the protrusions containing at least one of Cu, Zn, and Zr a contact angle that can avoid product defects. Since it is determined and controlled (set), product defects can be avoided. Specifically, the contact angle of water on the substrate surface before the washing / drying process hits a slider equipped with a recording and / or reproducing element when at least a recording layer is formed on the substrate to form an information recording medium. Is determined and controlled (set) so as to form a convex portion having a size (height) that does not cause an error and / or a size (height) that does not cause an error in recording and / or reproduction. Asperity can be prevented, or defect factors such as errors during recording / reproduction of the information recording medium can be eliminated. In the present invention, precision polishing (final polishing) is performed in the cleaning / drying process.
Immediate cleaning, cleaning after chemical strengthening, cleaning before shipping, cleaning immediately before film formation, and any cleaning performed between precision polishing and film formation. In any of the cleaning / drying processes, once the convex portion containing at least one of C, O, Al, Si, Fe, Cu, Zn, and Zr is formed, it cannot be removed in the subsequent cleaning process. It is preferable to determine and control (set) the contact angle of water on the substrate surface before all cleaning / drying steps so that the contact angle can avoid product defects. In the configuration 1, it is sufficient that the contact angle is equal to or less than the contact angle at which product defects can be avoided. Therefore, it is not necessary to reduce the contact angle more than necessary. That is, the contact angle can be determined in consideration of the cost. Here, the size (height) of the convex portion is C, O, Al, Si, Fe, Cu, Zn,
It may be a value obtained by directly measuring only the convex portion containing at least one of Zr, or may be obtained by measuring the surface roughness of the surface before and after the washing / drying step.

According to the configuration 2, by setting the contact angle of water on the substrate surface to a value that does not cause a glide defect (failed glide test) and an error when recording and / or reproducing, It is possible to manufacture a substrate for an information recording medium that can avoid the above defects.

According to the configuration 3, the contact angle of water on the substrate surface before the washing / drying process (particularly before the drying process) of the information recording medium substrate is set to 20 ° or less, so that the information recording medium substrate is C, O, Al, Si, Fe, C formed on
The height of the convex portion containing at least one of u, Zn, and Zr can be set to a height that does not cause product defects when used as an information recording medium. The smaller the contact angle of water on the substrate surface before the step of washing and drying the information recording medium substrate, the more C,
Since the height of the convex portion containing at least one of O, Al, Si, Fe, Cu, Zn, and Zr becomes low, the contact angle of water on the substrate surface before the cleaning / drying step is preferably 15 ° or less. It is more preferably 10 ° or less.

According to the configuration 4, in the method for manufacturing the information recording medium substrate, which has a step of packaging the information recording medium substrate obtained through the washing and drying steps, at least the packaging is unwrapped to form a film on the substrate. Before forming the film, the contact angle of water on the surface of the substrate immediately before pre-cleaning and drying is set to 20 ° or less (preferably 10 ° or less), or more preferably immediately after the washing / drying process as in the constitution 5. From before the step of pre-cleaning and drying before unpacking and forming a film on the substrate, the contact angle of water on the substrate surface is 2
By maintaining the temperature at 0 ° or less (preferably 10 ° or less), even if the spin dry drying is performed after only the DI water washing as the pre-washing, the height C that causes the product failure, O, Al, Si, Fe, Cu, Z
Since no convex portion containing at least one of n and Zr is formed, the manufacturing process can be shortened and the cost can be reduced. During the above period, the contact angle of water on the substrate surface,
Specific means for keeping the temperature at 20 ° or less (preferably 10 ° or less) is, for example, to shorten the time until the substrate is washed, inspected, and packaged, or packaged as a packaging material such as a case or a packaging bag for packaging the substrate. There are means such as using a packaging material with a small number of particles emitted from the packaging material or the discharged gas released from the packaging material, and packing with a desiccant in the packaging case or the packaging bag.

Structure 6 is defined because it is effective especially when the substrate material is a glass substrate.

Structure 7 is specified because the above-mentioned convex portion poses a particular problem when it is a magnetic disk substrate for the purpose of lowering the flying height of the magnetic head. The information recording medium substrate of the present invention is suitable for a magnetic disk substrate used in a magnetic disk application in which a slider performs recording and reproduction at a very small distance from the medium surface.

Further, when the above-mentioned convex portion is a substrate for a magnetic disk for a magnetoresistive head (MR head) for the purpose of preventing thermal asperity, it becomes a problem, especially for a giant magnetoresistive head (GMR head). The problem becomes more serious depending on the magnetic disk substrate. Therefore, the magnetic disk substrate is particularly effective as a magnetic disk substrate for a magnetoresistive head or a magnetic disk substrate for a giant magnetoresistive head.

Structure 8 is the above structure in the method of manufacturing an information recording medium, including the step of washing and drying before forming a film on the substrate for information recording medium (particularly the step of prewashing and drying immediately before film formation). It defines the same contents as 1.
This is because spin dry drying may be performed in the step of washing and drying before forming a film on the information recording medium substrate, and the above-mentioned convex portion is formed on the information recording medium substrate. This is because even if it is not formed, product defects cannot be avoided if the above-mentioned convex portions are formed in the step of washing and drying before forming the film.

The configuration 9 is the same as the configuration 2.

According to the structure 10, the contact angle of water on the substrate surface before the cleaning (in particular, the pre-cleaning immediately before the film formation) before forming the film on the information recording medium substrate is 20 ° or less. By doing so, C, O, Al, Si, Fe, Cu, Z as the main components formed on the information recording medium substrate are obtained.
The height of the convex portion containing at least one of n, Zr, and C can be set to a height that does not cause product defects when used as an information recording medium. As a method for controlling the contact angle of water on the surface of the substrate before cleaning before film formation to be 20 ° or less, for example, in addition to the method described in the configuration 4,
Examples include a method of treating in a cleaning tank (acid, alkali, neutral detergent, etc.) or a hydrophilic treatment tank (silicofluoric acid, etc.) before film formation.

In the present invention, the washing / drying process is particularly effective for a drying method which does not use a chemical solution. Examples thereof include spin dry drying, air knife (drying by blowing compressed air), and heat drying. Above all, configuration 1
1 is the occurrence of protrusions, especially cleaning with spin dry drying.
It is specified because it occurs in the drying process. In spin dry drying, usually only high speed rotation is used for drying. The spin dry may be a cassette type (batch type) or a single-wafer type, and a clean gas such as nitrogen may be flown in the dryer or sprayed on the substrate surface. For spin dry drying, a pure water shower is applied to the substrate surface to prevent the substrate from drying with washing or rinsing, and the pure water shower is stopped to dry at high speed, or the substrate surface is rotated while rotating at high speed. A method in which high-pressure water (pure water) is sprayed for cleaning, the spraying of high-pressure water is stopped, and drying is performed by high-speed rotation is included. Cleaning with spin dry
Drying includes a case where spin drying is performed only after cleaning with DI water, a case where spin drying is performed after rinsing with DI water, and the like.

Structure 12 is defined because it is effective when it is a glass substrate from which a substrate having high flatness and high smoothness can be obtained.

Structure 13 is defined because it causes a problem particularly when the above-mentioned convex portion is a magnetic disk intended to reduce the flying height of the magnetic head. Further, it is particularly effective for a magnetic disk mounted in an information recording apparatus using a magnetoresistive head or a giant magnetoresistive head as a magnetic head for recording and reproduction.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) In Embodiment 1, the results of investigations on the relationship between the contact angle and the height of the convex portion and the relationship between the contact angle and the glide defect will be shown.

The main surface of the disk-shaped glass substrate was precision-polished to have a surface roughness of Rmax = 5.3 to 9.3 nm and Ra = 0.
Thousands of glass substrates for magnetic disks having 6 to 1.0 nm and Rp = 2.8 to 5.5 nm were obtained. These glass substrates were sequentially immersed in a cleaning bath (applied ultrasonic waves) of neutral detergent, DI water, and IPA (isopropyl alcohol), and then dried in IPA (steam drying bath) to prepare a disk case (EMPAK).
Stored 25 sheets each. These disk cases were placed in a commercially available PE (polyethylene) packaging bag, the packaging bag was forcibly degassed, and the packaging bag was heat-sealed and sealed, and then stored in a clean room environment for several days. The disc case is a case in which the outer box is made of PP (polypropylene) and the inner substrate holder is made of PE (polyethylene), and the generation of organic release gas and particles is small.

Next, after measuring the contact angle of water on the surface of each substrate taken out from the disk case, it was immersed in DI water and dried by spin drying to obtain a glass substrate for a magnetic disk. In addition, the contact angle of water was measured by a measuring method called a liquid method (hereinafter, the same measuring method was used).

Observation of the surface of the glass substrate for a magnetic disk obtained above with a microscope and an electron microscope reveals that hemispherical convex portions having a size of about 1 to several μm are formed. Was confirmed. When the relationship between the contact angle of water on the surface of the substrate and the surface roughness of the substrate (height of the convex portion) was examined, it was found that as the contact angle of water before dipping in DI water and performing spin dry drying increased, the substrate It was confirmed that the surface roughness (height of the convex portion) of the product tended to increase (FIG. 1). In addition, this convex portion is formed by EDS (energy dispersive X-ray spectroscopy).
As a result, it was confirmed that the composition mainly contained Si and O. In addition, this convex portion is
-SIMS (Time of Flight Secondary Ion Mass Spec
trometry: time-of-flight secondary ion mass spectrometry), it was confirmed that the main component was SiOH.

A NiAl seed layer, a CrV underlayer, and a NiV seed layer were formed on both sides of the magnetic disk glass substrate after spin drying.
A CoCrPtB magnetic layer, a carbon protective layer, and a perfluoropolyether lubricating layer were formed to obtain a magnetic disk for MR head. A glide test was performed on the obtained magnetic disk (test condition: assuming a case where recording / reproducing is performed at a flying height of the MR head of 20 nm, the minimum flying height is set to 18 n).
The height of the magnetic head was changed from m to 10 nm). The result is shown in FIG. In FIG. 2, the left vertical axis shows the glide test pass rate, the right vertical axis shows the contact angle of water on the substrate surface before immersion in DI water and spin drying, and the horizontal axis shows the water on the substrate surface shown on the right vertical axis. Each substrate having a contact angle of is shown. In FIG. 2, the glide test pass rate is indicated by a bar and the contact angle is indicated by “◯”. As can be seen from FIG. 2, the contact angle of water on the surface of the substrate is high, and when the contact angle of water exceeds 20 °, gliding failure is high (glide test pass rate is low). Here, the glide yield (glide test pass (pass) rate, glide yield) is a test that literally detects protrusions above a certain height on the surface of the magnetic disk with a head that floats at a certain height over the entire circumference. Shows the probability of passing the glide test, and the lower yield shows that the probability of protrusion formation is higher. In this way, the relationship between the contact angle of water on the substrate surface before the cleaning / drying process and the height of the convex portion (substrate surface roughness) attached to the substrate surface obtained through the cleaning / drying process is grasped in advance. . Furthermore, when the slider is levitated, the allowable height of the protrusion (substrate surface roughness) that does not cause an error during hitting or recording / reproducing is compared with the height of the protrusion, and the height of the protrusion is compared. So that the contact angle of water on the substrate surface is less than a predetermined value (for example, 20 °).
By setting the following, it is possible to reliably prevent gliding defects and deterioration of the recording / reproducing function due to thermal asperity when a magnetic disk is formed using this substrate. In the actual manufacturing process of glass substrates for magnetic discs and magnetic discs, there is a correlation between the contact angle of water on the substrate surface before the cleaning / drying process, the glide yield, and the error occurrence rate during recording / reproduction. In that case, in such a case, simply setting the contact angle of water on the surface of the substrate to a value that does not cause gliding defects or errors during recording / reproduction will improve the gliding defects or the recording / reproducing function due to thermal asperity. The decrease can be prevented.

In Examples 2 to 6 shown below, in the method of manufacturing an information recording medium substrate having a step of packing the information recording medium substrate obtained through the washing and drying steps, the contact angle of water on the substrate surface The present invention provides a method (means) for suppressing the rise of the contact angle of water (specifically, the contact angle of water is 20 ° or less) in order to prevent gliding failure and the occurrence of thermal asperity. . In addition, in each of the examples, the elements caused by the contact angle of water are listed, and in relation to the contact angle of water, how each element should be controlled in order to suppress an increase in the contact angle (means). , Show its effect.

(Example 2) In Example 1 described above, it was found that the contact angle of water on the substrate surface before immersion in DI water and spin drying was related to the occurrence of convex portions. Section 2 shows the results of an examination of the type of packaging bag (released gas) and the contact angle of water on the substrate surface.

FIG. 3 is a front view showing the outline of a test carried out for investigating the relationship between the material of the packaging bag and the contact angle of water on the surface of the substrate. A PE bag and a PE / Al / PE laminated bag (thickness 0.08 mm) are prepared, and as shown in FIG. 3, at the bottom of the disk case in which 25 substrates are stored, the two types of the same size are used. Each packing bag piece was unfolded and put, and each of these disc cases was put in a PE bag, forcibly degassed, sealed by heat sealing, and stored in an environment of 50 ° C. and 90% RH for 24 hours. As a result of measuring the contact angle of water on the surface of each of the substrates placed under the above environment, the substrate containing the PE bag has an average contact angle of water of 50.4 as compared with the PE / Al / PE laminated bag. It was as high as °. Also, when the contact angle on the substrate was measured at the top, bottom, and intermediate (left and right) positions when stored in the case, the gas released from the packaging bag contacted and adhered to the substrate surface, and the contact angle was The contact angle of the bottom of the substrate closest to the packing bag piece was considered to be the highest, and was the highest. Therefore, the contact angle of water of the substrate stored in the disk case can be suppressed to a low level by using the packaging bag that does not release the released gas for increasing the contact angle of water. Actually, a magnetic disk was produced in the same manner as in Example 1 using a packaging bag with a small amount of released gas, and a glide test was performed after measuring the contact angle. The contact angle of water was 10 ° on all substrates. It was below the range, and no gliding defects occurred.

(Embodiment 3) In Embodiment 3, the result of examining the relationship between the amount of particles contained in the packaging bag and the contact angle of water with the substrate will be shown. Prepare three types of packaging bags, put a certain amount of pure water into each packaging bag so as to contact with a certain area of the bag, extract particles, and use LPC (Liquid particle counter) in each packaging bag. 0.5 μm included in
The amount of particles exceeding 10 was measured. The water contact angle of the substrates in these packaging bags was measured. The water contact angle of the substrate with the largest amount of particles (2387.5 Count / cm ³ ) was found to be in a relatively clean packaging bag. , 569.6 Count / cm ³ (contact angle 6.5 °),
20.8 Count / cm ³ (contact angle 5.2 °)] compared to 3
It was as high as 2.6 ° and defective glide occurred. In particular, since organic particles are hydrophobic, it is considered that the contact angle increases when they adhere to the substrate. On the other hand, a magnetic disk was produced in the same manner as in Example 1 by using the other two types of substrates placed in relatively clean packaging bags, and a glide test was conducted, but no glide failure occurred. From the above results, it was found that the amount of particles existing in the packaging bag is preferably as small as possible. Preferably 0.5 μm
It is desirable that the number of particles exceeding 1000 is 1000 Count / cm ³ or less, more preferably 500 Count / cm ³ or less, and further preferably 250 Count / cm ³ or less.

(Embodiment 4) In Embodiment 4, the results of examining the relationship between the temperature and humidity (moisture permeability) in the packaging bag and the contact angle of water on the substrate surface will be shown. After packaging and sealing the disk case-containing substrates with a PE bag containing a desiccant and a PE bag not containing a desiccant, and leaving the substrates for 3 months, the contact angle of water on the substrate surface was examined. The contact angle of water on the surface of the substrate in the packaging bag containing the desiccant was as low as 10 ° or less, but in the case of the substrate left for 3 months in the packaging bag containing no desiccant, the glass surface Partly burned, and the contact angle of water on the surface of the substrate exceeded 20 ° and became about 45 °. It is considered that this is because water molecules adhering to the glass surface repeated the action of adsorbing particles and the like and then evaporating. When a glide test was conducted in the same manner as in Example 1, the magnetic disk of the substrate having a high contact angle had high protrusions as in Example 1, and a glide defect occurred. On the other hand, a magnetic disk was produced in the same manner as in Example 1 using a substrate placed in an environment in which a desiccant was added and humidity was adjusted, and a glide test was conducted, but no glide failure occurred. Therefore, by putting the desiccant in the packaging bag, it is possible to suppress the increase in the contact angle of the substrate during long-term storage such as 3 months, and prevent the glide defect due to the convex portion.

(Embodiment 5) In Embodiment 5, after the substrate is washed, the time for leaving the substrate in a clean room and
The result of having investigated the relationship with the contact angle of water on the substrate surface is shown. Specifically, in the substrate manufacturing process, the substrate after precision polishing is subjected to final cleaning (shipping cleaning) directly or after passing through other processes, and after being stored in a storage case for shipping such as a disc case through an inspection process, It is shipped in a packing bag. It takes a considerable amount of time to leave the substrate in the clean room after the substrate is washed in the above process and then packaged through the inspection process. In Example 5, the effect was investigated.

Prepare 200 substrates after the final cleaning (shipping cleaning), leave 100 in the clean room with the cleaning basket for the substrates, and put the remaining 100 in the disk case, 25 each in a PE bag. Packed and sealed at
I kept it. For the substrates not put in the packaging bag, the contact angle of the substrates increased as the standing time passed immediately after the cleaning process. In particular, the contact angle of water on the substrate surface exceeded 20 ° after the standing time exceeded 70 hours. On the other hand, with respect to the substrate which was immediately put into the packaging bag and sealed after being washed and dried, the contact angle was not increased so much even after the lapse of time. Therefore, it can be seen that, for a substrate that has undergone a series of manufacturing processes (cleaning and drying processes have been completed), an increase in the contact angle of the substrate can be suppressed by shortening the standing time until packaging after the inspection process. . A magnetic disk was prepared in the same manner as in Example 1 using a substrate that was immediately placed in a packaging bag and sealed after cleaning and drying, and a substrate that had been left for 60 hours, and a glide test was performed, but no glide failure occurred. It was It is preferable that the time taken to package the substrate after the cleaning and drying steps through the inspection step is 70 hours or less. It is preferably within 30 hours, more preferably within 10 hours.

(Example 6) In Example 5, a substrate left in a cleaning basket and left in a clean room was cleaned with a cleaning tank (acid, alkali, neutral detergent, etc.) or a hydrophilic treatment tank (before processing). After being sequentially dipped in a hydrofluoric acid solution, a pure water tank, and a DI water tank, and then dried by spin drying, a convex portion having a height that would cause a product defect was not formed. In this case, the contact angle of water on the surface of the substrate before pre-cleaning is large, but the contact angle of water on the surface of the substrate before spin-drying becomes low due to the treatment in the cleaning tank or the hydrophilization treatment tank, so that a convex portion is formed. It will not be done. However,
If such a treatment is performed before film formation, the number of steps and the cost increase.

The present invention is not limited to the above embodiment. For example, the test conditions of the glide test are not limited to those in the above embodiment, and for example, assuming that the MR head has a flying height of less than 10 nm, the minimum flying height is 0 nm to 10 nm. The glide test may be performed by changing the height. Further, the substrate material is not limited to glass. For example, various materials such as aluminum, silicon, carbon, ceramics and titanium may be used. Further, the glass type of the glass is not limited, and the glass further includes chemically strengthened glass, crystallized glass and the like. Needless to say, the application is not limited to the magnetic disk substrate, but can be applied to an optical disk substrate and a magneto-optical disk substrate. As the hydrophilic treatment, KOH, NaO, etc. may be used in addition to the above method.
Examples thereof include an alkali treatment such as H, an acid treatment such as dilute sulfuric acid and nitric acid, and ozone oxidation by ultraviolet irradiation. The washing / drying step in the present invention is not limited to the washing / drying method and steps shown in the examples.

The present invention also includes the inventions described below. (Supplementary Note 1) In the method for producing a substrate for information recording medium having a washing / drying step of washing / drying the precision-polished substrate for information recording medium, the contact angle of water on the substrate surface before the washing / drying step, The correlation of the size (height) of the protrusions attached to the surface of the substrate obtained through the washing / drying step is obtained, and the protrusions form at least a recording layer on the substrate to form an information recording medium. And a size (height) that does not cause a hit when a slider equipped with a recording and / or reproducing element is run on the surface of the medium, and / or
Alternatively, the information is characterized in that the contact angle of water on the substrate surface before the cleaning / drying step is set so that the size (height) does not cause an error when recording and / or reproducing. Manufacturing method of recording medium substrate. (Supplementary Note 2) In the method for producing a substrate for information recording medium having a washing / drying step of washing / drying the precisely polished substrate for information recording medium, the contact angle of water on the substrate surface before the washing / drying step, An information recording medium is formed by forming at least a recording layer on the substrate, and further, a glide yield when a slider equipped with a recording and / or reproducing element is run on the medium surface, and recording and / or reproducing are performed. And the error occurrence rate at the time of contact, and the contact angle of water on the surface of the substrate is set to a value that does not cause gliding defects and errors during recording and / or reproduction. Of manufacturing a substrate for an information recording medium. (Supplementary Note 3) The method for producing a substrate for an information recording medium according to Supplementary Note 1 or 2, wherein the contact angle of water on the surface of the substrate before the cleaning / drying step is controlled to be 20 ° or less. (Supplementary Note 4) In a method of manufacturing an information recording medium substrate, which has a step of packaging an information recording medium substrate obtained through a washing / drying step, at least before unpacking and forming a film on the substrate. A method for manufacturing a substrate for an information recording medium, wherein a contact angle of water on the surface of the substrate immediately before pre-cleaning and drying is set to 20 ° or less. (Supplementary Note 5) From immediately after the washing / drying step to immediately before the step of pre-cleaning and drying before unpacking and forming a film on the substrate, the contact angle of water on the substrate surface is 20
The method for producing a substrate for an information recording medium as described in appendix 4, characterized in that the substrate is kept at a temperature of not more than °. (Supplementary Note 6) In a method for manufacturing an information recording medium substrate, which has a step of packaging an information recording medium substrate obtained through a washing / drying step, the material of the packaging bag used in the packaging step is discharged from the packaging bag. A method for manufacturing a substrate for an information recording medium, which is made of a material that suppresses an increase in the contact angle of water on the surface of the substrate due to the released gas. (Supplementary Note 7) The method for producing a substrate for an information recording medium according to Supplementary Note 6, wherein the material of the packaging bag is a material that maintains a contact angle of water on the surface of the substrate at 20 ° or less. (Supplementary Note 8) In the method of manufacturing a substrate for information recording medium having a step of packaging the substrate for information recording medium obtained through the washing / drying process, the amount of particles existing in the sealed space packed in the packaging process is controlled. A method for manufacturing a substrate for an information recording medium, wherein the amount is such that an increase in the contact angle of water on the substrate surface is suppressed. (Supplementary note 9) Manufacturing of the substrate for information recording medium according to supplementary note 8, wherein the amount of particles existing in the sealed space packed in the packing step is 1000 Count / cm3 or less for particles exceeding 0.5 μm. Method. (Supplementary Note 10) In a method for manufacturing an information recording medium substrate having a step of packing an information recording medium substrate obtained through a washing / drying step, to suppress an increase in contact angle of water on the substrate surface, A method for manufacturing a substrate for an information recording medium, characterized in that the humidity in the sealed space packed in the packing step is adjusted. (Supplementary Note 11) In a method of manufacturing a substrate for information recording medium having a step of packaging a substrate for information recording medium obtained through a washing / drying step, the substrate after the washing / drying step is packaged through an inspection step. A method for manufacturing a substrate for an information recording medium, characterized in that the time required to do so is within 70 hours. (Supplementary Note 12) By performing at least one or more of Supplementary Notes 6 to 11 in the method for manufacturing a substrate for information recording medium having a step of packing the substrate for information recording medium obtained through the washing / drying step, A method of manufacturing a substrate for an information recording medium, wherein the contact angle of water on the substrate surface is 20 ° or less. (Supplementary Note 13) The method for producing a substrate for an information recording medium according to any one of supplementary notes 1 to 12, wherein the substrate is a glass substrate. (Supplementary Note 14) The method for producing an information recording medium substrate according to any one of Supplementary Notes 1 to 13, wherein the information recording medium substrate is a magnetic disk substrate. (Supplementary Note 15) The method for producing a substrate for an information recording medium according to Supplementary Note 14, wherein the information recording medium substrate is a magnetic disk substrate for a magnetoresistive head or a giant magnetoresistive head. (Supplementary Note 16) A step of preparing a precision-polished substrate for an information recording medium, a step of washing and drying before forming a film on the substrate, and a step of forming at least a recording layer on the washed and dried substrate. In the method for manufacturing an information recording medium including the step, the contact angle of water on the surface of the substrate before the cleaning, and the size of the convex portion attached to the surface of the substrate obtained through the step of cleaning and drying ( Height),
A size such that the protrusion does not cause a hit when an at least recording layer is formed on the substrate to form an information recording medium, and a slider provided with a recording and / or reproducing element is run on the medium surface ( Contact angle of water on the surface of the substrate before the cleaning so as to obtain a height (height) and / or a size (height) that does not cause an error when recording and / or reproducing. A method for manufacturing an information recording medium, characterized in that: (Supplementary Note 17) A step of preparing a precision-polished substrate for an information recording medium, a step of washing and drying before forming a film on the substrate, and a step of forming at least a recording layer on the washed and dried substrate. And a contact angle of water on the surface of the substrate before the cleaning, and an information recording medium by forming at least a recording layer on the substrate, further comprising recording and / or recording and / or There is a correlation between the glide yield when a slider equipped with a reproducing element is run on the medium surface and the error occurrence rate when recording and / or reproducing is performed, and the contact angle of water on the substrate surface is Is a value that does not cause glide defects and errors during recording and / or reproduction, and a method for manufacturing an information recording medium. (Supplementary Note 18) The method for producing an information recording medium according to Supplementary Note 16 or 17, wherein the contact angle of water on the surface of the substrate before the cleaning is controlled to be 20 ° or less. (Supplementary note 19) The method for producing an information recording medium according to any one of supplementary notes 16 to 18, wherein the step of cleaning and drying is accompanied by spin dry drying. (Supplementary Note 20) The method for producing an information recording medium according to any one of Supplementary Notes 16 to 19, wherein the substrate is a glass substrate. (Supplementary Note 21) An information recording medium comprising at least a recording layer formed on the substrate for information recording medium obtained by the method for producing the substrate for information recording medium according to any one of Supplementary Notes 6 to 15. Production method. (Supplementary note 22) The method for producing an information recording medium according to any one of supplementary notes 16 to 21, wherein the information recording medium is a magnetic disk. (Supplementary Note 23) The method for producing an information recording medium according to Supplementary Note 22, wherein the information recording medium is a magnetic disk for a magnetoresistive head or a giant magnetoresistive head.

[0048]

As described above, according to the present invention, C,
The contact angle of water on the surface of the substrate before the cleaning / drying process, which causes a protrusion containing at least one of O, Al, Si, Fe, Cu, Zn, and Zr, becomes a contact angle that can avoid product defects. Therefore, product defects can be avoided. Specifically, a protrusion containing at least one of C, O, Al, Si, Fe, Cu, Zn, and Zr is not formed on the substrate surface even after a cleaning / drying process, or a hit or an error occurs. Since the convex portion having the generated height is not formed, it is possible to obtain a magnetic recording medium substrate and a magnetic recording medium capable of preventing head crash and deterioration of the recording / reproducing function due to thermal asperity. Similarly,
It is possible to eliminate a defect factor such as an error at the time of recording / reproducing of the information recording medium.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a contact angle of water on a surface of a substrate and surface roughness (height of a convex portion) of the substrate.

FIG. 2 is a diagram showing a relationship between a contact angle and defective glide.

FIG. 3 is a front view showing an outline of a test conducted for investigating the relationship between the material of the packaging bag and the contact angle of water on the surface of the substrate.

Continuation of the front page (56) Reference JP 2000-109817 (JP, A) JP 10-194785 (JP, A) JP 9-330515 (JP, A) JP 10-55535 (JP, A) JP 10-21537 (JP, A) JP 5-143981 (JP, A) JP 10-101459 (JP, A) JP 10-90503 (JP, A) JP 9 -236532 (JP, A) JP-A-8-148399 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 5/62-5/858

Claims (5)

(57) [Claims] 1. A method of manufacturing a glass substrate for a magnetic disk for a magnetoresistive head , comprising the steps of washing and drying a disk-shaped glass substrate whose main surface is precision-polished.
A contact angle of water on the surface of the glass substrate before the drying step, a magnetic disk having at least a recording layer formed on the glass substrate, and a slider equipped with a recording and / or reproducing element is run on the surface of the magnetic disk. There is a correlation between the glide yield of the glass substrate and the error occurrence rate of recording and / or reproducing, and the contact angle of water on the glass substrate surface before the cleaning / drying step is the same as that of the cleaning / drying. S adhering to the glass substrate surface in the process
The convex portion containing SiOH containing i and O as a main component has a glide defect, and a thermistor when recording and / or reproducing is performed.
A method of manufacturing a glass substrate for a magnetic disk for a magnetoresistive head, wherein an error is set to a value that does not cause lure asperity . 2. The production of a glass substrate for a magnetic disk for a magnetoresistive head according to claim 1, wherein the contact angle of water on the surface of the glass substrate before the washing / drying step is 20 ° or less. Method. 3. A method of manufacturing a glass substrate for a magnetic disk for a magnetoresistive head, which comprises a step of packaging a disk-shaped glass substrate obtained by subjecting a main surface to precision polishing and a washing / drying step, and at least the packaging. The magnetic resistance is characterized in that the contact angle of water on the surface of the glass substrate immediately before pre-cleaning and drying before forming a film on the glass substrate is set to 20 ° or less so as to prevent thermal asperity. For mold head
For manufacturing a glass substrate for a magnetic disk. 4. The contact angle of water on the surface of the glass substrate from immediately after the washing / drying step to immediately before the step of pre-cleaning and drying before unpacking and forming a film on the glass substrate. the claim 3, characterized in that kept less than 20 °
A method for manufacturing a glass substrate for a magnetic disk for a magnetoresistive head according to the above. 5. The magnet according to any one of claims 1 to 4.
A magnetic layer is formed at least as a recording layer on a glass substrate for a magnetic disk for a gas resistance type head.
A method of manufacturing a magnetic disk for a magnetoresistive head .