JPH08273155A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE: To improve gliding characteristics and to decrease defects by oxidizing the surface of an intermediate layer formed with a protective layer prior to formation of a protective layer to passivate the surface and washing the surface of the intermediate layer with a washing liquid. CONSTITUTION: A first ground surface layer 2, a second ground layer 3, a magnetic layer 4, the intermediate layer 5, the protective layer 6 and a lubricating layer 7 are formed successively on a glass substrate 1. A passivating stage for oxidizing the surface of the intermediate layer 5 formed with the protective layer 6 to passivate the surface prior to the formation of the protective layer 6 and a stage for washing the surface of the passivated intermediate layer 5 with the washing liquid are executed at the time of footing the magnetic recording medium. The physical strength of the respective films, smoothness, the adhesive power of the respective films to each other, etc., are thereby greatly improved, by which the gliding characteristic is improved and the defects are decreased. The higher coercive force of the magnetic film 4, the lower flying and traveling of the head slider and the higher CSS durability, etc., are embodied at a higher level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium used in a magnetic disk device.

[0002]

2. Description of the Related Art The demand for higher recording density for magnetic recording media such as hard disks has become increasingly severe in recent years.

Here, in general, a magnetic recording medium such as a hard disk is one in which a base film, a magnetic film, and a protective film are sequentially formed on a non-magnetic substrate, on which a head slider having a magnetic head mounted thereon is floated and run. While recording and reproducing. Therefore, in order to realize high density recording of this magnetic recording medium, in addition to high coercive force of the magnetic film, low flying of the head slider and CSS (contact st
It is important to improve durability against art and stop). That is, it is necessary to reduce the distance between the magnetic head and the magnetic film at the time of recording / reproducing by allowing the head slider to travel at a low flying height to enable high-density recording / reproducing. Also, if this low-flying travel is made,
During the repeated operation (CSS) of switching between sliding running and floating running when the head slider starts and stops running, the physical and mechanical load on the magnetic head and the magnetic recording medium increases rapidly. It is also necessary to improve the durability of the magnetic head and the magnetic recording medium (hereinafter, abbreviated as “high CSS durability”). Further, with the increase in recording density, it is more strictly required to reduce noise during reproduction.

By the way, in many current hard disks, an aluminum alloy substrate is used as a non-magnetic substrate, the surface of which is Ni--P plated and polished, and then textured to give an appropriate surface roughness. After that, the underlying film, the magnetic film, the protective film, and the like are sequentially formed by the sputtering method. That is, the unevenness resulting from the surface roughness due to the texture processing appears on the surface of the protective film through the underlying film and the magnetic film so that the head slider may be attracted to the magnetic recording medium during CSS, or
The frictional force between the two is prevented from becoming larger than a predetermined value.

A method has also been proposed in which a predetermined surface roughness appears on the surface of the protective film by forming a coating film of polysilicic acid or glass as the protective film (for example, Japanese Patent Publication No. 1-18500). (See the official gazette).

Further, recently, a magnetic recording medium using a glass substrate as a non-magnetic substrate has attracted attention as a medium having a high possibility of easily realizing a high recording density. This is because the glass has the small diameter of modern hard disks.
Achieves high recording density because it has excellent physical and chemical durability such as having sufficient hardness to support thinning, and has the property that its surface can be formed relatively easily with high planar accuracy. It has been found that it is more suitable for.

[0007]

By the way, in order to realize a high coercive force of a magnetic film, a low flying running of a head slider and a high CSS durability, which are necessary for high density recording of a magnetic recording medium, a substrate is required. Of course, it is necessary to improve the basic characteristics such as the magnetic characteristics of each film formed above,
Although it is required to improve the physical strength of each film, the smoothness, the adhesive force between the films, etc., the conventional magnetic recording media described above have a certain limit in improving such characteristics. .

The present invention has been made under the background described above, and provides a magnetic recording medium and a method of manufacturing the same, which can easily realize high coercive force, low flying height and high CSS durability. It is an object.

[0009]

In order to solve the above-mentioned problems, a method of manufacturing a magnetic recording medium according to the present invention comprises (Structure 1) at least an underlayer, a magnetic layer, an intermediate layer and a protective layer on a substrate. In a method of manufacturing a magnetic recording medium having a step of sequentially forming, prior to forming the protective layer, a passivation step of oxidizing the surface of an intermediate layer on which the protective layer is formed to passivate, and the passivation step. A cleaning step of cleaning the surface of the mobilized intermediate layer with a cleaning solution. As an aspect of the configuration 1, (configuration 2), the step of forming the protective layer forms the protective layer. A liquid raw material is adhered to the surface and heat treatment is performed, and the configuration is characterized in that (Configuration 3)
The cleaning step is characterized in that the surface of the layer to be cleaned is made wettable by the cleaning liquid at the end of the cleaning step. As an aspect of the configuration 2 or 3, (configuration 4) A main component and a main component contained in the liquid raw material of the protective layer are the same, and in any one of configurations 1 to 4, (configuration 5) the main component of the cleaning liquid is isopropyl alcohol And a configuration 1
As an aspect of any one of (1) to (5), (Structure 6) In the cleaning step, main cleaning is performed by shaking the substrate in one or more main cleaning tanks containing a cleaning liquid and applying ultrasonic vibration to the cleaning agent. And a finish cleaning step by rocking the substrate in a finish cleaning tank. As a configuration according to any one of configurations 2 to 6, (configuration 7) the protective layer The liquid raw material of (1) has a configuration in which hard fine particles are dispersed,
As an aspect of any one of configurations 1 to 7, (configuration 8)
A structure characterized in that the substrate is a glass substrate, and any one of the structures 1 to 8 (structure 9)
The underlayer is formed on the side in contact with the substrate.
i. Pb, Cu, Al, Ga, or In comprising a first underlayer containing any one or more of the main components as a main component, and a second underlayer containing Cr formed on the first underlayer As a mode of Configuration 9, (Configuration 10) The thickness of the first underlayer is 10 to 10
The structure is characterized in that it is 0 angstrom,
As an aspect of any one of configurations 1 to 10, (configuration 1
1) The material of the magnetic layer is a Co--X system (provided that X is
Is one or more of Ni, Cr, Ta, Pt, Zr, Si or B), and the material forming the intermediate layer is Cr or Cr-Y system (where Y is M).
o, Zr, B, W, Ta, or any one or more of Si)).

[0010]

According to the above configuration 1, the passivation step of oxidizing the surface of the intermediate layer on which the protective layer is formed to passivate it before forming the protective layer, and the passivation described above. By providing a cleaning step of cleaning the surface of the intermediate layer with a cleaning liquid, adhesion with a protective layer formed of a material excellent in adhesion with the passivated layer is made good, and at the same time, after the sputtering film formation by cleaning. By removing particle dirt on the film surface and reactivating the film surface so that these effects act synergistically, the physical strength of each film and the adhesive force between each film are significantly improved. It is possible to achieve a higher coercive force of the magnetic film, lower flying of the head slider, and higher CSS durability at a higher level, thereby achieving higher density recording of the magnetic recording medium. Became possible.

The fact that such a remarkable effect can be obtained by oxidizing the surface of the intermediate layer on which the protective layer is formed to passivate it, and at the same time, washing the intermediate layer is the first to be studied by the present inventors. It has been clarified. That is, conventionally, in addition to cleaning the substrate itself after polishing or texturing the substrate, not only cleaning is not particularly performed, but rather cleaning the layer formed on the substrate is cleaning. On the contrary, it was thought that even the surface of the existing film might be contaminated.

The present invention is more effective when the step of forming the protective layer is one in which the liquid raw material is adhered to the surface on which the protective layer is to be formed to form a film by heating as in the case of the constitution 2. Has been confirmed.

Further, as in the structure 3, the layer cleaned by the cleaning step is positively wetted to improve the film adhesive force and other film characteristics of the layer formed on this layer. In that case, as in the constitution 4, a larger effect can be obtained by making the main component of the cleaning liquid and the main component contained in the liquid raw material of the protective layer the same. As the cleaning liquid, It is preferable to use isopropyl alcohol as in the constitution 5.

Further, the cleaning step is performed as in the constitution 6.
Main cleaning step by shaking the substrate in one or more main cleaning tanks containing the cleaning liquid and applying ultrasonic vibration to the cleaning agent, and finishing cleaning step by shaking the substrate in the finishing cleaning tank A significant effect can be obtained by making it thorough such as the one having and.

Further, as in the constitution 7, the liquid raw material of the protective layer can be made to have an appropriate surface roughness by making the hard fine particles dispersed therein, and as in the constitution 8. The substrate is composed of a glass substrate, and as in the constitution 9, the underlayer mainly contains one or more of Al, Si, Pb, Cu, In or Ga formed on the side in contact with the substrate. And a second underlayer made of Cr formed on the first underlayer and having a thickness of 10 to 10 100 angstroms, and further, as in the constitution 11, the material of the magnetic layer is a Co—X system (where X is any one or more of Ni, Cr, Ta, Pt, Zr, Si or B). And the material constituting the intermediate layer is r or Cr-Y system (however, Y
Is one or more of Mo, Zr, B, W, Ta or Si), so that a magnetic recording medium can be obtained in which the effect of the present invention can be made more remarkable.

[0016]

【Example】

(Embodiment 1) FIG. 1 is a schematic sectional view showing a structure of a magnetic recording medium manufactured by a method of manufacturing a magnetic recording medium according to a first embodiment of the present invention. Hereinafter, the configuration of the magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to the first embodiment will be briefly described with reference to FIG. 1, and then the method for manufacturing the magnetic recording medium according to the first embodiment will be described. explain.

As shown in FIG. 1, the magnetic recording medium manufactured by the method of this embodiment is essentially a glass substrate 1.
The first underlayer 2, the second underlayer 3, the magnetic layer 4, the intermediate layer 5, the protective layer 6, and the lubricating layer 7 are sequentially formed on the above.

The glass substrate 1 is made of chemically strengthened glass and has an outer diameter of 95 mmφ, a central hole diameter of 25 mmφ, and a thickness of 0.8 mm.
Disk-shaped, and both main surfaces have a surface roughness of Rm
It was precision-polished to have an ax of 30 Å.

Here, the chemically strengthened glass constituting the glass substrate 1 contains SiO _{2 in a} weight percentage as a main component.
Is 62 to 75%, Al ₂ O ₃ is 5 to 15%, Li ₂ O is 4 to 10%, Na ₂ O is 4 to 12%, and ZrO ₂ is 5.5.
With each containing ~15%, Na ₂ O / ZrO
The weight ratio of ₂ is 0.5 to 2.0, the weight ratio of Al ₂ O ₃ / ZrO ₂ chemically strengthened glass is 0.4 to 2.5, N
What was chemically strengthened by ion exchange treatment in a treatment bath containing a ions and / or K ions (for details, see JP-A-5-32431) was used.

The first underlayer 2 is a thin film of Al having a thickness of about 50 Å.

The second base film 3 is a Cr film having a thickness of about 2000 angstroms.

The magnetic layer 4 is a CoNiCrTa film having a thickness of about 500 Å. Where CoNiCr
The Ta film has an atomic composition ratio of Co: Ni: Cr: T.
It has a composition of a = 66: 25: 8: 1.

The intermediate layer 5 is a Cr film having a film thickness of about 300 Å.

The protective layer 6 is one in which silica (SiO ₂ ) fine particles 5b are dispersed in a silicon oxide (polysilicic acid) film 6a, and irregularities due to the silica fine particles appear on the surface. The film thickness of the silicon oxide film 6a where the silica particles 6b are not present is about 100 angstroms. The silica fine particles 6b have an average particle size of about 10
It is 0 angstrom. Here, the average particle size of the silica fine particles is an average size of the silica fine particles, that is, a size obtained by measuring and averaging the diameter of a group of silica fine particles including silica fine particles having a spherical shape and a non-spherical shape. Means

The lubricating layer 6 is a lubricant made of perfluoropolyether (for example, AM2001 manufactured by Montedison Co.).
Is applied to the protective layer 6 by a dipping method to form a film thickness of about 20 Å.

Next, a method of manufacturing the magnetic recording medium of the embodiment will be described.

First, a chemically strengthened glass is prepared with an outer diameter of 65 mm.
φ, the hole diameter of the central part is 20 mmφ, and the thickness is 0.9 mm.
The glass substrate 1 is obtained by precision polishing so that the thickness becomes 0 angstrom.

Next, on the glass substrate 1, heat treatment of the glass substrate 1, film formation of the first underlayer 2, film formation of the second underlayer 3, heat treatment, film formation of the magnetic layer 4, intermediate layer. Each step of film formation of 5 is continuously performed using an in-line sputtering device.

As the in-line sputtering device, a well-known in-line type DC magnetron sputtering device was used. Although not shown, this in-line sputtering apparatus has a first chamber in which a substrate heating heater is installed, a second chamber in which an Al target and a Cr target are sequentially installed, and a first heater in which a heating heater is installed in the transport direction. The third chamber, the fourth chamber in which the CoNiCrTa target was sequentially installed, and the fifth chamber in which the Cr target was installed were respectively provided.

Then, when the glass substrate 1 is introduced into the first chamber through the load lock chamber, the glass substrate 1 is successively transported in the respective chambers by a predetermined transport device at a predetermined constant speed. During that time, the following film formation and processing are performed.

That is, first, in the first chamber, the substrate is heated at 375 ° C. In the second chamber, an Al film having a film thickness of 50 Å as the first underlayer 2 and a Cr film having a film thickness of 2000 Å as the second underlayer 3 are sequentially formed. In the third chamber, the substrate is heated again, and in the fourth chamber, the magnetic layer 4 of CoN having a film thickness of 500 angstrom is formed.
An iCrTa film is formed. In the fifth chamber,
Cr having a film thickness of 300 Å, which constitutes the intermediate layer 5
A film is deposited. The inside of each chamber is 1 x 10
Argon is used as a sputtering gas introduced into each of the above chambers after being depressurized to a pressure of ^-5 Torr or less. The sputtering gas pressure is 5 mT in the second chamber.
orr, 3 mTorr in the fourth chamber, and 5 mTorr in the fifth chamber.

Next, the substrate on which the intermediate layer 5 has been formed is taken out of the in-line sputtering apparatus and left in the atmosphere at room temperature for about 5 to 10 minutes to oxidize the surface of the intermediate layer 5 to passivate it. Give.

Next, the above-mentioned magnetic layer 4 is formed as much as possible 4.
The substrate on which the intermediate layer 5 is formed is washed within the time, more preferably within 30 minutes. This cleaning step consists of main cleaning in which the substrate is dipped in a main cleaning tank filled with a cleaning liquid for a predetermined time and pulled up, and finish cleaning in which the substrate after this main cleaning is dipped in a finish cleaning tank for a predetermined time and pulled up. In this case, isopropyl alcohol (IPA) having a purity of 95% or more is used as the cleaning liquid. In the main cleaning tank and the finish cleaning tank, the surface of the substrate is immersed perpendicularly to the liquid surface, and the upper and lower movements are given in parallel with the surface of the substrate, while ultrasonic cleaning is performed. Furthermore, the temperature of the cleaning liquid in the main cleaning tank is approximately 30 ° C.
The substrate is immersed in the cleaning liquid in the main cleaning tank for about 3 minutes, and the pulling rate is about 10 mm / sec. Main cleaning is 3
Repeatedly using the main cleaning tank of the tank. The temperature of the cleaning liquid in the finish cleaning tank is set to 25 ° C. or higher and 35 ° C. or lower, the time for immersing the substrate in the cleaning liquid in the finish cleaning tank is set to about 2 minutes, and the pulling rate is set to about 2 mm / sec. It should be noted that it is preferable to stop the ultrasonic wave when starting the pulling from the finish cleaning tank. Further, it is preferable that the liquid temperature of the cleaning liquid is higher than the liquid temperature of the main cleaning and the liquid temperature of the final cleaning is 35 ° C. or lower at the same time. When the temperature is 35 ° C. or higher, it becomes difficult to impart appropriate wettability to the surface of the intermediate layer 5. Further, it is preferable to provide three or more main cleaning tanks, but it has been confirmed that a certain effect can be obtained even with one tank. In addition, the pulling speed in the main cleaning is set higher than the pulling speed in the finishing cleaning in order to minimize the possibility of dust adhesion, while in the finishing cleaning, the surface of the intermediate layer 5 is made semi-dry. This is to have appropriate wettability. In this case, the pulling speed during finishing cleaning is 10 m at 0.5 mm / sec or more.
Within the range of m / sec, it is possible to give a predetermined wettability. If it is 0.5 mm / sec or less, the surface of the intermediate layer 5 is completely dried, and there is a high possibility that the protective film formed in the next step has defects such as film peeling. On the other hand, if it is 10 mm / sec or more, there is a high possibility that the protective film formed in the next step may have defects such as a large amount of film formation unevenness due to excessive wetting.

Next, after pulling up in the above-mentioned finish cleaning,
Within 90 seconds, the surface of the intermediate layer 5 is brought into contact with the liquid material in which the hard particles are dispersed, the liquid material is applied, and heat treatment is performed to form the protective layer 6. In this case, this liquid is
Tetraethoxysilane (S
i (OC ₂ H ₅ ) ₄ ), silica fine particles having an average particle size of about 100 Å (measured by Coulter Counter N4 manufactured by Coulter Counter Co., Ltd.), water, and isopropyl alcohol in a weight ratio. 1
It is an organic silicon compound solution containing silica fine particles mixed in a ratio of 0: 0.3: 3: 500. The heat treatment after applying the liquid material is a treatment of heating at a temperature of about 280 ° C. for 2 hours. As a result, the protective layer 6 in which the silica fine particles 6b are dispersed in the silicon oxide (polysilicic acid) film 6a
Is obtained.

Next, the substrate having the protective layer 6 formed thereon is washed with pure water and IPA.

Then, a lubricant made of perfluoropolyether (for example, AM2001 manufactured by Montedison Co., Ltd.) is applied on the protective layer 6 by a dipping method to form a lubricating layer 7 having a film thickness of about 20 Å, and thereafter, Then, the protrusions are removed from the surface of the magnetic recording medium by using a burnish head to obtain a magnetic recording medium.

The surface roughness of the magnetic recording medium thus obtained was measured using a Taristep manufactured by Rank Taylor Hobson Co., and the maximum height (Rmax) was 15
It was 0 angstrom.

This magnetic recording medium also passed the 300 Å glide test.

Next, contact start by a magnetic head using an Al ₂ O ₃ —TiC sintered body as a slider portion.
100,000 in the stop test (CSS test)
The static friction coefficient after rotation was 0.4 or less, and it had excellent wear resistance.

When the coercive force of this magnetic recording medium was measured, it was 1900 Oersted, which was extremely excellent.

Furthermore, the flying height of the magnetic head is 0.055 μm.
When a recording / reproducing output at a linear recording density of 70 kfci (linear recording density of 70,000 bits per inch) was measured using a thin film head of m, the relative speed between the head and the disk was 6 m / s, a high value of 245 μV was obtained. Was obtained.

Further, the noise spectrum during signal recording and reproduction was measured by a spectrum analyzer with a carrier frequency of 8.5 MHz and a measurement band of 15 MHz.
The thin film head used in this measurement has 50 coil turns, a track width of 6 μm, and a magnetic head gap length of 0.25 μm. As a result, the noise is 1.9 μVrm
It was a small value of s.

Further, the magnetic characteristics measured under the above conditions were also good, and high density recording of 80 KBPI (kilobits / inch) or more was possible at D50.

Next, in order to confirm the effect of the presence or absence of the cleaning step, the magnetic recording medium manufactured by the manufacturing method of this embodiment and the manufacturing method of this embodiment except for only the cleaning step were manufactured. For the magnetic recording medium of the comparative example, the number of defects (defects) when the error test was performed by changing the linear recording density value and the number of glide hits when the glide test was performed by changing the head flying height were measured. The result is shown. The defect number is the number of bits indicating an output below a certain level (slice level) with respect to the average output. In this embodiment, the slice level is 85% and the linear recording density is 10, 20, ... , 110, 120KF
The value in each case of CI was measured. In addition, the number of glide hits means that the signal from the piezo element attached to the head slider that has a constant flying height is a certain value (slice level) or more when the head slider is vibrated by the protrusions on the disk. When the head flying height is 0, 10, 20,
The value in each case of 140, 150 nm was measured. Figure 2
Is a table showing the measurement results of the defect number, FIG. 3 is a graph showing the measurement results of FIG. 2, FIG. 4 is a table showing the measurement results of glide head number, and FIG. Figure 4
It is the figure which showed the measurement result of above as a graph.

As is clear from the above-mentioned comparison results, when there is no cleaning step, defects are already seen from 30KFCI, and the number of defects exceeds 100 at 60KFCI.
Prevents high density of magnetic disks. Moreover, since the glide hit number starts to be detected when the flying height is about 50 nm, it is difficult to further reduce the flying height of the head.

On the other hand, in the case of this embodiment, 60K
It can be seen that defects can be detected only near the FCI, and the number of glide hits is hardly detected up to the flying height of 30 nm, which is extremely excellent.

For comparison, a magnetic recording medium having the same structure and manufacturing method as in Example 1 was prepared except that the first underlayer 2 was not formed, and the characteristics thereof were the same as those in Example 1. The coercive force was 140
0 Oersted, recording / reproducing output was 200 μV, and noise was 4.0 μV rms, which were inferior to those of Example 1.

Further, for comparison, a magnetic recording medium of a comparative example having the same structure and manufacturing method as the above-mentioned Example 1 including the base film, except that the protective layer 6 was formed of a carbon thin film, was prepared. When the characteristics were examined by the same measuring method as in Example 1, the coercive force was 1300 Oersted, the recording / reproducing output was 190 μV, and the noise was 2.1 μVrm.
However, the coercive force and the recording / reproducing output were inferior to those of Example 1 although the noise characteristics were the same. Further, the number of defects (defects) generated when the magnetic recording medium of the comparative example and the magnetic recording medium of the present example were stored in a high temperature and high humidity atmosphere of 80 ° C. and 85% was measured by a measuring machine (Hitachi Electronics Engineering Co., Ltd.). According to the result of time-course investigation using a company-made RC560 media certifier), the magnetic recording medium of this example does not show any defect even if it is stored under high temperature and high humidity for a long time. It was found that when the magnetic recording medium of the example was stored under the same conditions, the occurrence of defects was observed in a short period of time and the defects increased remarkably with time.

Further, for comparison, except that the thickness of the first underlayer 2 was increased to 150 angstroms, the magnetic recording medium manufactured by the same structure and manufacturing method as in Example 1 had the same coercive force. The recording and reproducing output was 1600 oersted, the recording and reproducing output was 210 μV, and the noise was 3.7 μVrms. The coercive force was the same, but the recording and reproducing output and the noise characteristics were inferior to those of the first embodiment.

(Embodiment 2) FIG. 6 is a schematic sectional view showing a partial structure of a magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to a second embodiment of the present invention. As shown in FIG. 6, in the magnetic recording medium according to this example, a non-magnetic layer formed on the second underlayer 3 instead of the magnetic layer 4 in the magnetic recording medium manufactured in Example 2 described above. 41, the first magnetic layer 42 formed on the non-magnetic 41, the first magnetic layer 42
An intermediate nonmagnetic layer 43 formed on the magnetic layer 42, and a magnetic layer 40 composed of a plurality of second magnetic layers 44 formed on the intermediate nonmagnetic layer 43 are formed.

Further, in the manufacturing method of this embodiment, the magnetic layer 4
In addition to the step of forming the magnetic layer 40 in place of the step of forming the magnetic layer 40, the same configuration as that of the first embodiment is included, including a cleaning step of cleaning the intermediate layer 5 formed on the magnetic layer 40. Therefore, the common parts are denoted by the same reference numerals and the description thereof will be omitted.

The thickness of the nonmagnetic layer 41 in this embodiment is 1
It is a CrMo alloy film of 00 angstrom. This C
The composition of the rMo alloy film is 98 atomic% of Cr and 2 atomic% of Mo. The nonmagnetic layer 41 is provided in order to improve the crystal structure of the magnetic layer formed thereon.

The first magnetic layer 42 and the second magnetic layer 44 are both made of the same material, CoPtCr alloy, and have a film thickness of 120 Å. The composition of the CoPtCr alloy is as follows: Co at 78 at%, Pt at 11 at%, C
r is 11 atomic%.

The intermediate non-magnetic layer 43 is a CrMo alloy film having a film thickness of 50 Å. The CrMo alloy film has a composition of 95 atomic% of Cr and 5 atomic% of Mo.

Each film of the magnetic layer 40 is sequentially formed in the in-line sputter device by sputtering using Ar gas as a target and using Ar gas.

As described above, when the characteristics of the magnetic recording medium manufactured by the method of Example 2 in which the magnetic layer was composed of a plurality of layers were measured by the same measuring method as in Example 1, the coercive force was 1900 Oersted. , The highest recording density is D50, 1
00Kfci, CSS coefficient is 100 or less after 0.4000, static friction coefficient is 0.4 or less, glide test is the same as Example 1, noise characteristic is 0.8 μVrms, which is particularly excellent in noise characteristic as compared with Example 1. It was a thing.

Although the present invention has been described with reference to the embodiments, the present invention includes the following modifications and applications.

Although the chemically strengthened glass is used as the substrate in the above-mentioned embodiment, other glass such as soda lime glass, borosilicate, aluminosilicate, aluminoborosilicate, quartz glass, or ceramics may be used. You can These can be easily finished by polishing the surface to a surface roughness Rmax of 100 angstroms or less. Further, the outer diameter of the substrate may be smaller and the thickness may be thinner. Further, in addition to the glass substrate, an aluminum substrate or a ceramic substrate may be used.

In the embodiment, the case where the first underlayer is Al is mentioned, but this is Si, Pb, Cu, Ga or In.
Any one or two or more of them may be used as a main component. Further, in the examples, the case where the second underlayer is Cr is mentioned, but it is TiW, Mo, Ti, Ta, W, Z.
A non-magnetic material such as r, Cu, A, Zn, In or Sn can be used.

The base layer may be a single layer or three or more layers.

Examples of the magnetic layer include CoNiPt, CoNiCr, CoNiZr and CoC in addition to the examples given in the examples.
Other C such as rPt, CoPt, CoP, CoCrPtB
The magnetic layer may be made of a magnetic material such as an o-based alloy or Fe ₂ O ₃ .

Further, although Cr is used in the embodiment as the intermediate layer formed between the magnetic layer and the protective layer, other materials may be used, for example, Mo, Ti, TiW, Cr.
It may be made of a non-magnetic material such as Mo, Ta, W, Si or Ge, or a non-magnetic thin film made of a nitride or a carbide thereof. Further, these nonmagnetic thin films may be formed by forming a plurality of two or more layers.

The formation of the underlayer, magnetic layer, and intermediate layer is as follows.
It is needless to say that the ordinary sputtering apparatus can be used instead of the in-run phosphorus sputtering apparatus.

Further, in the embodiment, the example in which the protective layer is composed of the hard fine particles dispersed therein is shown. However, the protective layer may not necessarily be composed of the hard fine particles dispersed therein. For example, the protective layer may be composed of a carbon film. Good.

Further, as the raw material for forming the protective layer, tetraethoxysilane, which is an organic silicon compound, was used in the examples, but a partial or complete hydrolyzate thereof may be used, or by the so-called sol-gel method. Other silicon alkoxides or partial or complete hydrolysates thereof may be used as long as they form silicon oxide. Such examples include tetramethoxysilane, tetra-n-
Propoxysilane, tetra-1-propoxysilane, tetra-n-putopoxysilane, tetra-sec-ptoxysilane, tetra-tert-ptoxysilane, and other tetraalkoxysilanes, and 1 to 3 of these tetraalkoxysilane alkoxy groups are alkyl groups. Silicon monoalkoxides such as monoalkyl trialkoxysilanes, dialkyl dialkoxy silanes and trialkyl monoalkoxy silanes and their partially or completely hydrolyzed products.

Further, as the hard fine particles dispersed in the protective layer, silica fine particles are listed, but other hard fine particles such as ceramics and alloys may be used.

Further, the thickness of the region in the protective layer where the hard fine particles do not exist is 100 Å in the embodiment, but it is preferable that the thickness is in the range of 20 to 200 Å. The reason is that if the thickness is less than 20 angstroms, the inorganic oxide film becomes too thin and the force for holding the hard particles becomes small, so that the CSS durability is deteriorated and the inorganic oxide film cannot serve as a protective film and the magnetic layer is not formed. This is because deterioration occurs, and a spacing loss problem occurs when the thickness exceeds 200 angstroms. Also,
The surface roughness (Rmax) of the magnetic recording medium is 50 to 50 using hard particles having an average particle size of 50 to 350 angstrom.
This range is also preferable in order to obtain 300 angstroms. Further, the hard fine particles may have two or more different average particle sizes mixed within this range. In particular, in the magnetic recording medium for contact recording, it is desirable that the average particle size is in the range of 50 to 200 angstrom.

The surface roughness (Rmax) of the magnetic recording medium is
50-300 Angstroms are preferred. The reason is that if the thickness is less than 50 Å, the magnetic head cannot be prevented from being attracted. On the other hand, if it exceeds 300 Å, the operability of the magnetic head on the medium is unstable when the head flying height is 400 to 500 Å. , Head crashes are more likely to occur,
The magnetic recording / reproducing characteristics also deteriorate. In contact recording, in particular, if the distance between the magnetic layer and the head changes with time, that is, if it vibrates, the magnetic characteristics are seriously affected. Therefore, it is important not to exceed 300 angstroms.

Further, although perfluoropolyether was used as the material of the lubricating layer in the examples, a fluorocarbon liquid lubricant or a lubricant composed of an alkali metal salt of sulfonic acid may be used. The film thickness is preferably 10 to 30 Å, and the reason is 10
If it is less than angstrom, the wear resistance cannot be sufficiently improved, and if it exceeds 30 angstrom, the wear resistance is not improved and a problem of spacing loss occurs.

[0070]

As described above in detail, according to the method for manufacturing a magnetic recording medium of the present invention, before forming the protective layer, the surface of the intermediate layer on which the protective layer is formed is oxidized to prevent imperfections. By providing a passivation step of activating and a washing step of washing the surface of the passivated intermediate layer with a washing liquid, the physical strength of each film, the smoothness, the adhesive force between the films, etc. It is possible to achieve remarkable improvement, which can improve the glide characteristics and reduce defects, improve the coercive force of the magnetic film, reduce the flying height of the head slider, and improve the CSS durability. It has become possible to achieve high-level recording on magnetic recording media.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration of a magnetic recording medium manufactured by a method of manufacturing a magnetic recording medium according to a first embodiment of the present invention.

FIG. 2 is a result of measuring the number of defects at each linear recording density for the magnetic recording medium manufactured by the manufacturing method of Example 1 and the magnetic recording medium manufactured by the manufacturing method of Example 1 except only the washing step. It is the figure which showed as a table.

FIG. 3 is a diagram showing the table of FIG. 2 as a graph.

FIG. 4 is a graph showing the number of glide hits at each head flying height of the magnetic recording medium manufactured by the manufacturing method of Example 1 and the magnetic recording medium manufactured by the manufacturing method of Example 1 except only the washing step. It is the figure which tabulated and showed the result of having done.

5 is a graph showing the table of FIG.

FIG. 6 is a schematic cross-sectional view showing the structure of a magnetic recording medium manufactured by the method of manufacturing a magnetic recording medium according to Example 2 of the present invention.

[Explanation of symbols]

1 ... Glass substrate, 2 ... First underlayer, 3 ... Second underlayer,
4, 40 ... Magnetic layer, 5 ... Intermediate metal layer, 6 ... Protective layer, 7 ...
Lubricating layer, 41 ... Nonmagnetic layer, 42 ... First magnetic layer, 43 ... Intermediate nonmagnetic layer, 44 ... Second magnetic layer. ．

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Horikawa 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Hoya Co., Ltd.

Claims (11)

[Claims] 1. A substrate, at least an underlayer, a magnetic layer,
In a method of manufacturing a magnetic recording medium, which comprises a step of sequentially forming an intermediate layer and a protective layer, a passivation that oxidizes the surface of the intermediate layer on which the protective layer is formed to passivate it before forming the protective layer. And a cleaning step of cleaning the surface of the passivated intermediate layer with a cleaning liquid. 2. The magnetic recording medium according to claim 1, wherein in the step of forming the protective layer, a liquid raw material is adhered to a surface on which the protective layer is formed and heat treatment is performed. Manufacturing method. 3. The method of manufacturing a magnetic recording medium according to claim 1, wherein in the cleaning step, the surface of the layer to be cleaned is made wettable by the cleaning liquid at the end of the cleaning step. Method. 4. The method for producing a magnetic recording medium according to claim 2, wherein the main component of the cleaning liquid and the main component contained in the liquid raw material of the protective layer are the same. 5. The method of manufacturing a magnetic recording medium according to claim 1, wherein a main component of the cleaning liquid is isopropyl alcohol. 6. The cleaning step comprises a main cleaning step in which one or more main cleaning tanks containing a cleaning liquid are shaken by a substrate and ultrasonic vibration is applied to the cleaning agent, and a finishing cleaning tank is used. 6. A method of manufacturing a magnetic recording medium according to claim 1, further comprising a finishing cleaning step by rocking the substrate. 7. The method of manufacturing a magnetic recording medium according to claim 2, wherein the liquid raw material of the protective layer is one in which hard particles are dispersed. 8. The method of manufacturing a magnetic recording medium according to claim 1, wherein the substrate is a glass substrate. 9. The first underlayer formed on the side in contact with the substrate, the first underlayer containing any one or more of Si, Pb, Cu, Al, Ga, and In as a main component. 9. A second underlayer made of Cr formed on one underlayer, wherein the second underlayer is formed.
A method for manufacturing a magnetic recording medium according to any one of 1. 10. The thickness of the first underlayer is 10 to 100.
10. The method for manufacturing a magnetic recording medium according to claim 9, wherein the magnetic recording medium is Angstrom. 11. The material of the magnetic layer is a Co—X-based material (where X is any one or more of Ni, Cr, Ta, Pt, Zr, Si or B) and the intermediate The material forming the layer is Cr or Cr-Y type (however,
Y is any one of Mo, Zr, B, W, Ta or Si.
Or 2 or more). The method for manufacturing a magnetic recording medium according to claim 1, wherein