JP2002319127A - Cleaning method for magnetic recording medium by sponge pad pressurizing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the reduction of the dropping of contaminations from a cleaning tape itself and the suppression of slight damage which may be a reproduction signal error given to the surface of a magnetic disk compatible with each other. SOLUTION: The occurrence of the contaminations can be suppressed and the slight error can be remarkably reduced, since the burr part at the end part of the tape is not loaded and the contaminations on the surface of the tape are not directly scattered by air, by adopting a pressurizing suspension system wherein the tape is pressurized by a sponge material having the width narrower than that of the tape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for removing dust adhering to the surface of a magnetic disk in a manufacturing process or an abnormal projection generated in a medium film forming process or the like using a cleaning tape. The present invention relates to a method of manufacturing a magnetic disk for a magnetic disk device including the same.

[0002]

2. Description of the Related Art In recent years, with the development of the information industry, the performance required of computers has become increasingly sophisticated. Along with this, the recording density and the capacity of magnetic recording media as external storage devices have been increasing. In recent years, new compact disk drives have been added to increase the capacity and to complement each other's recorded data, thereby preventing the destruction of recording due to failures that tend to occur in magnetic disk drives. Magnetic disk array systems with functions are also commercially available.

On the other hand, a magnetic disk is usually subjected to so-called texture processing for forming fine concentric stripes on the surface of an aluminum alloy substrate which has been subjected to Ni-P plating and mirror-polished, and then introduced into a vacuum apparatus for sputtering. The mainstream is a magnetic disk completed by forming a base film, a magnetic film, and a protective film in this order, then cleaning the surface, applying a lubricant, and a manufacturing process. Have also begun to be marketed.
As a manufacturing method in this case, the glass substrate is mirror-polished,
After chemical cleaning, a vacuum device is used to form a base film, a magnetic film, and a protective film in this order, and then a lubricant is applied, the surface is cleaned, and a method is completed.
In particular, a small magnetic disk using this glass substrate may not be textured as compared with the above-mentioned aluminum alloy substrate, and the surface roughness and the protrusion height (hereinafter, referred to as “height”) will be described.
Rp. ), The center line average roughness (hereinafter referred to as Ra) is as small as several angstrom, and burrs are also reduced. This is important for reducing the spacing between the recording / reproducing magnetic head and the magnetic disk, which is essential for increasing the recording density. In fact, the guaranteed height of the magnetic head flying above the magnetic disk has rapidly decreased in recent years, and recently, a value of 10 nm or less has been required. For this purpose, it is necessary to further flatten the surface of the magnetic disk and to remove dust or abnormal protrusions having a height equal to or higher than the flying height which hinder the floating of the magnetic head.

In order to guarantee a decrease in the flying height, a tape film to which abrasive grains have been fixed is conventionally pressed against the disk surface with a rubber roller.
Japanese Patent Application Laid-Open No. 63-153723 discloses a method disclosed in Japanese Patent Application Laid-Open No. 63-153723 or a method disclosed in Japanese Patent Publication No. 2-10486, or a method in which a gas is blown against the tape and pressed against and polished. After forming the protective film, a step of cleaning the surface is indispensable. In the conventional cleaning process, there were many contaminants such as abnormal protrusions due to burrs on the substrate and dust on the surface of the magnetic disk, and the surface roughness itself of the substrate was large. Therefore, the surface cleaning technique obtains a sufficient processing amount for cleaning the object requiring removal as described above.
As described in Japanese Patent Publication No. 6, the cleaning performance and processing performance have been maintained with a large abrasive particle size of 1 to 3 microns. This depends on the fact that the larger the abrasive grain size, the greater the surface roughness of the tape and the greater the amount of processing.

[0005]

However, in the recent magnetic disk manufacturing process, as described above, in the case of a glass substrate or the like, the polishing technique and precision of the substrate before forming a sputtered film have been remarkably improved, and the surface of the disk has been remarkably improved. Roughness is Rp
What used to be a few tens of nanometers in the past is now down to a few nanometers, and the disk is completed by optimizing the conditions for forming a sputtered film on top of it and improving the cleanliness of the atmosphere inside the vacuum equipment. The removal requirements for the previous finishing cleaning process have been significantly reduced,
The problems of damaging the disk by the cleaning process itself and transferring and remaining contamination such as processing residues have begun to be highlighted.

[0006] In view of the above problems, a problem with the conventional cleaning method in the future is that, first, in the case of a tape material having a large abrasive grain size, the spacing between the magnetic head and the disk becomes narrower. Damage caused by the tape to the disk surface becomes a serious problem as an error level of the recording / reproducing signal. In other words, as the particle size of the abrasive grains increases,
It has been found that the depth of the scratches on the disk surface is increased and the number of scratches is also increased. As a result, the number of errors in the recording / reproducing signal is increased and the defective yield is deteriorated.

Here, an output signal error mode in the recording / reproducing process of the magnetic disk will be described. The error described here is a mode called a missing error, and the output level is reduced due to a defect such as a partial lack or a partial recess of the cobalt alloy magnetic layer responsible for magnetic recording. It is in a state to be. In the conventional case, a shallow scratch did not cause a problem because the track width of the magnetic head was several microns, but since the track width becomes 1 micron or less in the future, the rate of counting as an error is necessarily large. Become. In addition, the thickness of the protective layer mainly composed of carbon, which is overcoated on the magnetic layer, also tends to become thinner as the recording density of the magnetic disk increases, and the above-mentioned scratches which cause the above-mentioned errors are caused. , It becomes difficult to obtain sufficient strength to protect the magnetic layer.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 2000-348337, attention has been paid to the effect of reducing the particle size of the abrasive grains of the cleaning tape in order to suppress the above-mentioned scratches that cause an error. It is being viewed and generalized. On the other hand, if the particle diameter is reduced, foreign matter (contamination) falling off the cleaning tape itself increases, which causes a problem that it adheres to the surface of the magnetic disk.

Accordingly, an object of the present invention is to provide a tape cleaning step for a magnetic disk surface having a small surface roughness, to reduce contamination from falling off from the cleaning tape itself, and to minimize errors in reproduced signals given to the magnetic disk surface. It is an object of the present invention to provide a magnetic disk cleaning system capable of minimizing the number of scratches and removing a protrusion that may hinder the floating of the magnetic head.

[0010]

Means for Solving the Problems By using a cleaning tape having a small abrasive particle size, scratches due to the cleaning tape on the magnetic disk surface can be reduced,
The depth of the wound can be reduced. On the other hand, as a new problem, adverse effects due to the reduction in the particle size include processing wastes or falling off from the polishing layer (hereinafter referred to as contamination).
It has been found that contamination has been buried from the surface of the magnetic disk into the interior of the disk, resulting in a slight scratch, and the present invention has found the following solution.

Most of the causes of contamination are detachment of the cleaning tape from the end of the tape. The end of the tape is scattered with burrs (turning of the processed layer in the direction of entry of the cutting blade) generated when cutting with a slitter, and such burrs easily adhere to the magnetic disk surface as contamination. In state.
Atmosphere (clean air, clean air,
Hereinafter, it is called air. ) Is applied to the magnetic disk surface by spraying the tape on the tape (hereinafter referred to as an air blow method), whereas the present invention employs a suspension method in which the tape is pressed with a sponge material narrower than the tape width.
Since no load is applied to the tape end and contamination of the tape surface by air is not directly scattered, it has been found that the occurrence of contamination can be suppressed and minor errors can be significantly reduced. .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described in detail with reference to the drawings. Embodiment 1 FIG. 1 shows a sectional structure of a magnetic disk to be cleaned. Hereinafter, conditions for forming each layer will be described. First, a thickness of 0.635 millimeter, an outer diameter of 65 millimeters, an inner diameter of 20 millimeters, and a surface roughness of 100 square microns using an atomic force microscope (hereinafter, referred to as AFM) were measured. Rp = 5.0 nanometers , R
The aluminosilicate glass substrate whose a = 0.8 nanometer, 2.5-inch type surface is chemically strengthened is washed, and a single-wafer sputtering apparatus (MDP250B) manufactured by Intevac is used thereon. The following multilayer film was formed in 7.5 seconds. Ni-20at% Cr-15at having a thickness of 40 nanometers on the substrate 10
First underlayer films 11 and 11 'made of a% Zr alloy were formed. Then, Co-30at% of 10 nanometer thickness
Second underlayer 12, 1 made of Cr-10at% Zr alloy
2 'was formed. Then, while heating the temperature of the substrate to about 230 ° C. by a lamp heater, 99% Ar-1% in the same room.
4. In an atmosphere of O2 mixed gas at a pressure of 10.5 mTorr,
Exposure for 0 seconds, followed by a 23 nanometer thick Cr-2
Third underlayers 13 and 13 'made of a 0 at% Ti alloy were formed. On top of that, 8.8 nanometers thick Co-22
First magnetic film 1 made of at% Cr-12at% Pt alloy
4, 14 'and then 8.8 nanometers thick Co-22 at% Cr-12 at% Pt-4 at% B
Second magnetic films 15, 15 'made of an alloy were formed. Further, protective films 16 and 16 'each containing 6 nm of carbon as a main component were formed thereon. Thereafter, the substrate is taken out of the sputtering apparatus, and a lubricant containing perfluoroalkyl polyether as a main component is applied on the protective film to a thickness of 2.
Lubricating films 17 and 17 'of 1 nanometer were formed.

In the present invention, the surface of the layer was cleaned. Here, the cleaning after the application of the lubricant reduces the frictional force of the polishing layer on the surface to be processed by interposing the lubricating layer between the protective layer and the cleaning tape with respect to the scratches to be solved according to the present invention. By doing so, the effect that scratches are unlikely to occur was found in advance.

Here, contamination caused by the tape cleaning step, which is an object to be suppressed in the present invention, will be described. FIG. 2A shows a scanning electron microscope (SEM) image of the tape surface before magnetic disk cleaning, and FIG. 2B shows an SEM image after cleaning. Before the cleaning, burrs turned up at the time of cutting are seen at the end of the tape. The burrs are mainly composed of abrasive grains mainly made of alumina and a binder mainly containing carbon for fixing the abrasive grains. The above-mentioned burrs have disappeared on the tape surface after cleaning. From this, it can be seen that the burrs at the ends are transferred to the surface of the magnetic disk as contamination. FIG. 3 shows an SEM image of the contamination attached to the magnetic disk surface. The contaminants that are stretched and adhered in the circumferential direction of the disc can be seen.

Next, FIG. 4 shows a schematic view of a tape cleaning apparatus of the present invention for suppressing the above-mentioned contamination. This cleaning device has a pair of mechanisms for tape cleaning both surfaces of the magnetic disk 21,
Each mechanism is configured to apply a tension between a feed reel 23 around which the cleaning tape 22 is wound and a guide roller 24 to the tape 22 via the tape 22 sent from the reel 23 by gravity. Mechanism 25, and guide rollers 24 and 26 for guiding the tensioned tape to the magnetic disk surface.
And a mechanism for pressing a pressure block 28 with a sponge pad 27 attached thereto at a predetermined pressure by a spring 29 against the tape 22 guided on the magnetic disk surface to slide the tape against the magnetic disk. And a take-up roller 31 that collects through the guide roller 30. FIG. 5 is an enlarged schematic view of the pressing unit mechanism. The pressure unit is a method in which a pressure block to which a sponge pad is fixed is pressed against the back surface of the tape via a coil spring. For the adjustment of the pressing force, the set length of the spring was changed with an adjusting screw, and the pressing force was detected by a load cell arranged on the terminal side of the spring and output by an amplifier. Also,
As the sponge pad, a high-density foam made of urethane (PORON, LE-20 manufactured by INOAC CORPORATION) was used. Physical properties are: density 0.20 gram per cubic centimeter (JIS-K-6401), tensile strength 3.1 kilogram per square centimeter (JIS-K-6301), compression residual strain 5.9% (JIS-K-6401), 25 % Compression load 0.2 kilograms per square centimeter (JIS
-K-6301). The sponge pad dimensions were 3.0 mm in thickness, 10.6 mm in width, and 5.0 mm in length. For this dimension, the width of the tape is 12.6 mm, and the sponge is in a non-contact, that is, no-load area, 1.0 mm from each end of the tape. The cleaning tape used was AWA15000TNY-D manufactured by Nihon Micro Coating Co., Ltd. This is because the polishing abrasive is made of aluminum oxide abrasive, has a curved surface without an edge (average particle diameter D50 = 0.3 micron), and is suitable in terms of material and shape as polishing abrasive which hardly generates scratches. is there. The cleaning condition was that the disk was rotated leftward at a constant rotation speed without winding the tape while the sponge pad was being pressed. The tape head reciprocates three times at a moving speed of 400 mm / min in the radial direction of the disk, with the movement from the outer end side to the inner end side being the outward path and the movement from the inner end side to the outer end being the return path. Was. The contact pressure of the tape on the disk surface was measured by a load cell and was set to 60 gram weight. The result of cleaning the magnetic disk surface under the above conditions will be described below.

FIG. 6 shows a comparison of the tape contact pattern when the cleaning tape is pressed between the method of the present invention and the air blow method. This pattern is made of oil-resistant magic ink, which is obtained by pre-coloring a total of four lines at 90 ° intervals in the radial direction of the magnetic disk at 200 rotations per minute, pressing the tape and holding it at the outer peripheral position of the disk for 30 seconds. After that, traces of ink transferred to the tape were collected. The contact pattern in the air blow method is poor in reproducibility of the trace shape even when sampling under the same conditions, such as an arc shape or a linear contact state with a short length. On the other hand, in the method of pressing a sponge pad according to the present invention, a rectangular pattern that is the shape of the pad is accurately reproduced. This indicates that the repetition stability of the polished area involved in the cleaning is high, and the stabilization of the contact area means that the cleaning, that is, the processing work amount is stable.

Further, in order to verify the generation margin of the contamination, a comparison was made in an acceleration test in which the contamination easily occurred. The number of contaminations was determined by counting contaminations of 0.5 μm or more with a defect detection device manufactured by Hitachi Electronics Engineering which detects the reflection intensity of the laser (hereinafter, the number of contaminations is the value of the measurement device). ). FIG. 7 shows the relationship between the rotation speed of the disk and the amount of contamination. When the rotational speed of the disk is increased, the frictional force depending on the relative speed between the disk surface and the tape surface increases, so that the abrasive layer of the tape tends to fall off and the contamination tends to increase. However, even if the tape is damaged by increasing the rotation speed, the contamination hardly increases when the cleaning is performed by the method of the present invention even under the condition that the damage to the tape is increased. This is due to the fact that most of the contamination, as described above, is caused by the loss of the brittle part called the burr at the end of the tape, and in the method of the present invention, the pressing area of the sponge pad avoids the above-mentioned end. It is thought that it is possible to make it difficult to increase contamination. Further, an effect of reducing scratches (hereinafter referred to as "scratch") which destroys the recording film by embedding abrasive grains in the surface of the magnetic disk was obtained. This scratch correlates with an error mode called a missing error. The missing error is a parameter serving as a failure determination reference element in a magnetic disk completed product inspection process. FIG. 8 shows a comparison of the number of missing errors between the method of the present invention and the air blow method cleaning. The cleaning conditions were the same as those described above, with a rotation speed of 200 revolutions per minute for both types. The measurement of the missing error was performed using a magnetoresistive head (track width = 1.25 microns) manufactured by Seagate Inc. at a frequency of 90 kFCI, a rotation speed of 7000 revolutions per minute, a slice level of 86%, and a track pitch of 1.3 microns. In the range from 14.03 mm to 30.05 mm in the radial position, the auto gain control function was turned off, and the average of 100 measurement surfaces was determined as the number of errors. In the case of a missing error, the error size is divided into the following three stages.
Correctable error (CM) 1.12 microns or less, uncorrectable error (UM) 1.40 to
4.76 microns, long error (LM) 5.04
Micron or more. From these results, it was found that the method of the present invention can significantly reduce the average number of errors in each of CM, UM, and LM as compared with the air blow method. this is,
When the tape cleaning is performed under the same conditions, the air blow method often causes contamination from the tape end, whereas the sponge pad pressurizing method of the present invention can reduce the occurrence of contamination. It is presumed that the destruction of the magnetic recording film due to the embedding, that is, so-called scratching, was reduced, and a magnetic disk surface with few missing errors was obtained. As a result, in the inspection process of the magnetic disk on the production line, the yield of determining the electrical characteristics is improved. FIG. 9 shows the defective ratio of the electric characteristics of the cleaning method of the present invention and the cleaning of the air blow method. As a result of performing the cleaning according to the present invention, the defective rate of electrical characteristics was reduced by 20%. The inspection conditions are the same as those for the above-described missing error measurement. (Second Embodiment) In the pressing mechanism system shown in FIG. 5 of the first embodiment, the problem is the unevenness of the pressure distribution in the pressing surface due to the temporal deformation of the sponge shape and the runout of the disk. . That is, when the sponge comes into contact with the disk via the tape, the pressure applied to the disk surface is not evenly distributed in the contact surface of the sponge. As a method for solving this, a pressure mechanism shown in FIG. 10 was invented.
In this mechanism, the pressure block to which the sponge is fixed swings around the centering pin, and when the sponge comes into contact with the disc and is pushed in by an arbitrary pressing force, pressure is applied to the disc surface. Is characterized in that the pressure block is positioned at a position where the pressure blocks are evenly dispersed and in an equilibrium state. Furthermore, during the cleaning process,
Since the disk is rotated, the waviness or runout of the disk in the circumferential direction acts as a repulsive stress on the pressure block, and the amount of the fluctuation is uncertain. The effect of (1) is that the block oscillates so that the pressure distribution in the sponge surface is always uniform, and the sponge contact surface follows the disk surface. Therefore, even if the shape of the sponge changes over time or the amount of runout of the disk changes, the pushing pressure applied to the disk by the sponge is uniform within the sponge contact surface, and the cleaning effect can be obtained stably. Can be FIG.
Fig. 2 shows a schematic diagram of the pressure distribution in the sponge surface. Example 3 A magnetic disk device as shown in FIG. 12 was manufactured by incorporating the magnetic disk manufactured under the manufacturing conditions of Example 1. 101 is a magnetic disk, 102 is a magnetic disk drive, 103 is a magnetic head, 104 is a voice coil motor for driving the magnetic head, and 105 is a recording / reproducing signal circuit system. As the magnetic head, a composite type head having both an electromagnetic induction type head for recording and a magnetoresistive head for reproduction was used. The gap length between the recording magnetic poles was 0.3 microns. Copper having a thickness of 3 microns was used for the coil. The reproducing head comprises a magnetoresistive sensor and electrode patterns at both ends of the magnetoresistive sensor. Both magnetoresistive sensors are sandwiched between a lower recording magnetic pole / upper shield layer and a lower shield layer having a thickness of 1 micron, and the distance between the shield layers is 0.20 micron. It is. (Example 4) A magnetic disk array system as shown in FIG. 13 was manufactured using a magnetic disk device incorporating a magnetic disk manufactured under the manufacturing conditions of Example 1. Reference numeral 201 denotes a magnetic disk array system housing, 202 denotes a magnetic disk device, and 203 denotes a magnetic disk array control unit.

[0018]

As described above, the method for manufacturing a magnetic disk according to the present invention includes the step of cleaning the magnetic disk by a suspension method in which the tape is pressed with a sponge pad narrower than the tape width, whereby contamination on the surface of the magnetic disk is reduced. Generation can be suppressed, and scratches that can cause errors in the reproduced signal can be reduced. Further, by manufacturing the magnetic disk according to the present invention by the above-described steps, it is possible to minimize the number of scratches that may cause an error in the reproduction signal applied to the magnetic disk surface, and to remove the protrusion that may hinder the flying of the magnetic head. . Further, the magnetic disk drive and the magnetic disk array system according to the present invention can improve the reliability of data recording and reproduction by mounting the magnetic disk.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a magnetic disk.

FIG. 2A is a diagram illustrating an SEM image of a cleaning tape (before cleaning), and FIG. 2B is a diagram illustrating an SEM image of the cleaning tape (after cleaning).

FIG. 3 shows a contamination SEM on a magnetic disk surface.
The figure which shows an image.

FIG. 4 is a schematic view of a tape cleaning device.

FIG. 5 is a schematic view of a tape cleaning device pressing mechanism.

FIG. 6 is a diagram for explaining the stability of a pressure contact pattern.

FIG. 7 is a diagram showing the relationship between the disk rotation speed and the number of contaminations.

FIG. 8 is a diagram showing the relationship between the pressure method and the number of missing errors.

FIG. 9 is a diagram showing a relationship between a pressurization method and a failure rate of electrical characteristics.

FIG. 10 is a schematic view of a pressure mechanism swing mechanism.

FIG. 11 is an in-plane pressure distribution diagram when a sponge is pressed.

FIG. 12 is a schematic diagram of a magnetic disk drive.

FIG. 13 is a schematic diagram of a magnetic disk array system.

[Explanation of symbols]

Reference numeral 10: substrate, 11, 11 ': first underlayer, 12, 12'
... Second base film, 13, 13 '... Third base film, 14, 1
4 ′: first magnetic film, 15, 15 ′: second magnetic film, 16,
16 ': protective film, 17, 17': lubricating film, 21: magnetic disk, 22: cleaning tape, 23: delivery reel, 24: guide roller, 25: constant tension mechanism, 26: guide roller, 27: sponge pad, 2
Reference numeral 8: pressure block, 29: spring, 30: guide roller, 31: take-up roller, 101: magnetic disk,
102: magnetic disk drive, 103: magnetic head,
104: voice coil type motor for magnetic head, 10
5: recording / reproducing signal circuit system, 201: magnetic disk array system, 202: magnetic disk device, 203: magnetic disk array control unit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Susumu Susumumoto 2880 Kozu, Odawara City, Kanagawa Prefecture Inside the Hitachi, Ltd.Storage Division (72) Inventor Fuminobu Maruyama 2880 Kozu, Kozuhara, Odawara City, Kanagawa Prefecture Hitachi, Ltd. Within the Storage Division (72) Inventor Takanori Nagano 2880 Kozu, Odawara-shi, Kanagawa F-term within the Storage Division, Hitachi, Ltd. F-term (reference) 5D006 DA03 EA03 EA04 FA09 5D112 AA24 GA08 GA12 GA13

Claims (5)

[Claims] 1. A method of manufacturing a magnetic recording medium comprising a carbon protective layer formed on a magnetic layer comprising a ferromagnetic alloy thin film provided on a non-magnetic substrate, wherein said protective layer surface has abrasive grains fixed thereon. Wrapping tape with a width of 80
% And 97% or less, and the physical properties are 25% compression load (J
IS-K-6301), including a cleaning step characterized by a method of pressing through a sponge or a rubber foam which is not less than 0.1 kilograms per square centimeter and not more than 1.0 kilograms per square centimeter. A method for manufacturing a magnetic recording medium. 2. The magnetic recording method according to claim 1, wherein the pressing mechanism for fixing the sponge pad is a cleaning method having a mechanism characterized by a swing structure. The method of manufacturing the medium. 3. A magnetic disk manufactured by using the manufacturing method according to claim 1. 4. A magnetic disk drive using a magnetic disk manufactured by using the manufacturing method according to claim 1. 5. A magnetic disk array system using a magnetic disk device using a magnetic disk manufactured by using the manufacturing method according to claim 1.