JPH08306040A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE: To prevent the occurrence of flows on the surface of a disk and to improve error characteristics and sliding durability to a head by carrying out a vanishing process by oxidation treatment and forming a lubricant layer by vapor phase polymn. CONSTITUTION: This magnetic recording medium is produced through a process for forming a magnetic layer on a nonmagnetic substrate, a process for forming a protective layer on the magnetic layer, a vanishing process for reducing the height of abnormal protrusions existing on the surface of the protective layer and a process for forming a lubricant layer on the protective layer. The vanishing process is carried out by oxidation treatment by heating the substrate at 400-600 deg.C in an oxidizing atmosphere of air, ozone, CO2 , steam, etc. The lubricant layer is formed by bringing a fluorocarbon compd., preferably this compd. and oxygen into vapor phase polymn. under vacuum conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium. More specifically, it relates to a magnetic recording medium represented by a hard disk in which a magnetic layer is formed on a non-magnetic substrate by a method such as dry plating.

[0002]

2. Description of the Related Art In a magnetic disk system, when reproduction output is taken into consideration, it is advantageous that the distance (flying height) between the magnetic recording medium and the magnetic head is small, that is, the spacing loss is small. In other words, it is desirable that the magnetic disk surface be smooth.

However, in general, a magnetic disk has minute projections called "abnormal projections" on the surface after formation of a protective layer or after application of a lubricant. The height is lowered to finish the surface. Such an operation of removing the abnormal protrusion on the disk surface by a physical means is usually called "burnish".

The burnishing process using a polishing tape is basically performed by applying an appropriate pressure to the surface of the magnetic disk with a polishing tape in which abrasive grains such as amylna and diamond are provided on a flexible support by an organic binder. It is carried out by bringing them into contact with each other and running the disk and the polishing tape. As such a burnishing process, for example, in the manufacturing process of a magnetic disk medium, after the surface of the magnetic disk medium is processed using a polishing tape, a polishing tape is used in order to effectively remove only minute projections existing on the surface. Using a medium peripheral speed of 250 m / min or more, tape processing pressure of 50 g
/ Mm ² or less, a method of manufacturing a magnetic disk medium is proposed (Japanese Patent Laid-Open No. 59-148134, Japanese Patent Publication No. 2-104).
No. 86).

[0005]

However, in the burnishing process using a polishing tape, since the abrasive grains in the polishing tape are not uniform in grain size but have a distribution (unevenness) in the grain size, the abrasive grains having a large grain size are large. There is a problem in that the abrasive grains dropped from the tape or the tape damage the disk surface and cause an error, resulting in a decrease in yield.

Further, if the polishing powder or grinding powder generated by polishing remains on the disk surface, it collides with the head to lower the sliding durability and damage the magnetic layer and the protective layer. Moreover, if the polishing powder or the grinding powder remains on the disk surface, the liquid lubricant or water is gathered around the remaining particles due to the capillary phenomenon, which causes head adsorption.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an excellent burnishing method capable of solving the above-mentioned problems of burnishing with a polishing tape when removing abnormal protrusions on the surface of a magnetic recording medium. As a result of earnest research by the present inventors, a chemical burnishing method by oxidation treatment satisfies this requirement, not a physical burnishing method like burnishing by a conventional polishing tape. Further, it was found that the sliding durability can be further improved by forming a lubricant layer on the substrate which has been subjected to such burnishing treatment by vapor phase polymerization, and completed the present invention.

That is, according to the present invention, at least a step of forming a magnetic layer on a non-magnetic substrate, a step of forming a protective layer on the magnetic layer, and a burnish for reducing the height of abnormal protrusions existing on the surface of the protective layer. In the method for manufacturing a magnetic recording medium having a step and a step of forming a lubricant layer on the protective layer, the burnishing step is performed by an oxidation treatment, and the lubricant layer is formed in a vapor phase under vacuum conditions. The present invention provides a method for manufacturing a magnetic recording medium, which is characterized in that polymerization is performed.

In a usual hard disk manufacturing process, a substrate is textured (the surface is appropriately roughened), washed, a magnetic layer is formed on the substrate, and then a protective layer is formed on the magnetic layer. After that, after performing a burnishing step of removing abnormal protrusions on the disk surface and adjusting the height to an appropriate height, a lubricating layer is formed on the protective layer. In such a manufacturing process, a step of providing an underlayer or the like under the magnetic layer is added if necessary. The manufacturing method of the present invention is characterized in that in the known manufacturing process, a so-called burnishing process is performed by an oxidation treatment, and the lubricant layer is subjected to gas phase polymerization under vacuum.

(A) Oxidation burnishing step In the present invention, the burnishing step by oxidation treatment is
It is carried out by heating the substrate in an oxidizing atmosphere such as air, ozone, carbon dioxide or water vapor. The heating method is
Examples include heating of heating wires such as a nichrome wire heater and heating by an infrared lamp. Heating temperature is 300-1000
C., especially 400 to 600.degree. C. are preferred. When the heating temperature is high, the device may be distorted, so it is necessary to consider the material of the device. If the heating temperature is too high, when the protective layer is formed of carbon such as diamond-like carbon, the carbon may diffuse into the magnetic layer and the coercive force (Hc) may decrease. The heating time is 0.1 to 60 minutes, and 0.5 to 5 minutes is particularly preferable in consideration of productivity. The amount of reduction in the height of abnormal protrusions (removal amount of protrusions) due to the oxidation treatment can be precisely controlled by operating the oxidation temperature, time, and the like. Further, the “oxidation treatment” in the present invention does not mean strict oxidation but also includes a phenomenon in which abnormal protrusions are decomposed / vaporized / vaporized by heating. Therefore, the burnishing method of heating the substrate in a vacuum is also included in the oxide burnish of the present invention.

(B) Gas Phase Polymerization Step The present invention includes a step of forming a lubricant layer on the protective layer by gas phase polymerization. The gas phase polymerization may be carried out using a fluorocarbon compound alone, but is preferably carried out by reacting a fluorocarbon compound with oxygen.

The above-mentioned fluorocarbon compounds include carbon-
Those having a carbon double bond are preferable, and particularly preferably selected from the group consisting of compounds represented by the following general formulas (I) to (III).

CF ₂ = CFR _f ¹ ... (I) (wherein R _f ¹ is a fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, CF ₂ ═C (R _f ² ) (R _f ³ ) ... (II) (wherein R _f ² and R _f are represented by a perfluoroaryl group or a partially fluorinated aryl group)
^{3 is the same or different hydrogen atom, fluorine atom, perf
Luoroalkyl group, perfluoroalkenyl group, partial group
Fluorinated alkyl group, partially fluorinated alkenyl group, perf
Indicates a fluoroalkyl group or a partially fluorinated aryl group
) CF} 2 ^{= CFO (R} f ⁴ ) ... (III) (In the formula, R _f ⁴ is a fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group or a partially fluorinated alkenyl group. Represents a perfluoroaryl group or a partially fluorinated aryl group) The fluorocarbon compounds may be used alone or in combination of two or more. When two or more kinds are used, two or more kinds may be selected and used from any one of the general formulas (I) to (III), or among the general formulas (I) to (III). One or more kinds may be selected from each of at least two categories.

In R _f ¹ of the general formula (I), preferable perfluoroalkyl groups are perfluoromethyl group (CF ₃ —) and perfluoroheptyl group (C ₅ F).
₁₁ -), perfluorohexyl group (C ₆ F ₁₃ -). Examples of the preferably perfluoroalkenyl group, perfluoro ethynyl (CF ₂ = CF-). Preferable examples of partially fluorinated alkyl group , 1H-perfluorobutyl group (C ₄ F ₈ H-). preferable examples of partially fluorinated alkenyl group, -CF ₂ -CF = CH ₂
And examples of the preferred perfluoro aryl group, perfluoro benzyl group (-CF ₂ -C ₆ F ₅₎ and the like, and, as a preferred partially fluorinated aryl group, -CFH-C ₆ H ₅ and - CF ₂ -C ₆ H ₅ and the like.

Therefore, among the compounds represented by the general formula (I), preferred are tetrafluoroethylene (CF ₂ ═CF ₂ ), hexafluoropropene (CF _2).
= CFCF ₃ ), perfluoroheptene-1 (CF ₂ =
CFC ₅ F ₁₁ ), 6H-perfluorohexene-1 (C
F ₂ = CFC ₄ F ₈ H), perfluorooctene-1 (CF
= CFC ₆ F _13), hexafluoro-1,3-butadiene
_{(CF 2 = CFCF = CF 2} ), 3- ( pentafluorophenyl) pentafluoropropene -1 (CF ₂ = CFCF _{2
C 6 F 5), CF 2} = CFCHF-C 6 H 5, CF 2 = CFC
_{F 2 -C 6 H 5, CF} 2 = CFCF 2 CF = CH 2 and the like.

In R _f ² and R _f ³ of the general formula (II),
Preferred perfluoroalkyl groups include —CF ₂ CF _{3 in} addition to those in the above general formula (I), and preferred perfluoroalkenyl groups include the above general formula
In addition to those in (I), -CF ₂ -CF = CF ₂ may be mentioned, and preferable partially fluorinated alkyl group is -CF
₂ H and —CF ₂ CF ₂ H, preferred partially fluorinated alkenyl groups include —CF ₂ —CF═CH ₂ , and preferred perfluoroaryl groups and partially fluorinated aryl groups include the above. The same thing as the thing in general formula (I) is mentioned.

Therefore, among the compounds represented by the general formula (II), preferred ones are CF ₂ ═C (CF ₃ ) ₂ ,
CF ₂ = CH ₂ , CF ₂ = CHF, CF ₂ = CHCF ₃ , C
F ₂ = CHCF ₂ CF ₃ , CF ₂ = CHCF = CF ₂ , CF
₂ = CHCF ₂ CF = CF ₂ , CF ₂ = CHCF ₂ H, CF
_{2 = CHCF 2 CF 2 H,} CF 2 = CHCF 2 CF = CH 2,
_{CF 2 = CHCF = CH 2,} CF 2 = CHCFH-C
_{6 F 5, CF 2 = CHCF} 2 -C 6 H 5 and the like.

In R _f ⁴ of the above general formula (III), preferable perfluoroalkyl groups and perfluoroalkenyl groups are the same as those in the above general formula (II). the _{-CF 2 H, -CF 2 CF 2} H and -C ₄ F ₈ H, and the like, preferably partially fluorinated alkenyl group, a perfluoro aryl and partially fluorinated aryl group, the general formula (II) It can be mentioned those similar to the ones in and preferred perfluoro alkoxyalkyl _{group, -CF 2 CF (CF 3)} OC 3 H 7 and the like.

Therefore, among the compounds represented by the general formula (III), preferred ones are CF ₂ ═CFOCF ₃ ,
CF ₂ = CFOC ₅ F ₁₁ , CF ₂ = CFOC ₆ F ₁₃ , CF ₂
= CFOCF ₂ CF ₃ , CF ₂ = CFOCF = CF ₂ , CF
₂ = CFOCF ₂ CF = CF ₂ , CF ₂ = C ₄ F ₈ H, CF ₂
= CFOCF ₂ H, CF ₂ = CFOCF = CF ₂ H, CF _{2
= CFOCF 2 -CF = CH 2,} CF 2 = CFOCF = C
_{H 2, CF 2 = CFOCF 2} -C 6 F 5, CF 2 = CFOCF
_{H-C 6 H 5, CF} 2 = CFOCF 2 -C 6 H 5, CF 2 =
_{CFOCF 2 CF (CF 3) OC} 3 H 7 , and the like.

The ratio of the fluorocarbon compound to oxygen used is preferably a fluorocarbon compound / oxygen (molar ratio) of 1 / 0.5 to 1/100, more preferably 1/1 to 1/1.
10, most preferably 1/2 to 1/8. When the use ratio is within the above range, the absorption efficiency of laser light and the like is good, and the polymerization reaction proceeds smoothly, so that a lubricating layer having more excellent durability is formed, which is preferable.

The polymer of a fluorocarbon compound and oxygen is a polymer mainly having a-(CF ₂ O)-structural unit, and its molecular weight is preferably 1500 to 300.
00.

Although the structure of the above polymer is not completely known, for example, a polymer represented by the following structural formula is presumed. X- (CF ₂ O) _l- (CF ₂ CF ₂ CF ₂ O) _m- (CF (CF ₃ ) CFO) _n X '[wherein l, m and n are positive integers (provided that l
>> m, n), and x and x'represent an end portion containing an alcohol or ether bond, an ester bond, a urethane bond or the like. ] Then, the in the polymer - (CF ₂ O) - the content of the structural units is preferably at least 70% in the total structural units, for example, in a polymer represented by the structural formula ( It is preferable that 1 / l + m + n) × 100 is 70% or more.

The lubricant layer of the magnetic recording medium of the present invention comprises a fixed layer fixed to the protective layer and a free layer formed on the fixed layer. Here, the fixed layer is
The layer that is chemically or physically strongly fixed to the maximum layer and is not washed off by washing with a fluorine-based solvent such as a product name "CFC113", and the free layer is the above. It is a layer that is washed away when washed with a fluorine-based solvent.

The ratio of the thickness (weight) of the fixed layer to the thickness (weight) of the free layer is preferably (thickness of free layer) / (thickness of fixed layer). Is 1/10 to 10/1,
More preferably, it is 2/5 to 5/1. The fixed layer preferably has a thickness of 5 to 30 liters because it has excellent wear resistance. Further, it is preferable that the thickness of the free layer is 2 to 80 liters because the durability is excellent and the friction coefficient is small.

As described above, in the magnetic recording medium of the present invention, the thickness of the above free layer is set to the conventional free layer thickness (8 to 20).
The thickness of the free layer in the present invention is the same as that of the free layer in the conventional magnetic recording medium because the friction coefficient of the surface of the magnetic recording medium does not become high (difficult to adsorb) even if it is thicker than Å. It can be thicker than the thickness.

The thickness of the lubricant layer comprising the fixed layer and the free layer is preferably 2 to 200 Å because the lubricity is good and the spacing loss is small, and more preferably 10 to 100 Å, Preferably 20-8
It is 0Å, most preferably 20 to 50Å.

In the vapor-phase polymerization step of the present invention, a lubricant is synthesized by vapor-phase polymerization of a fluorocarbon compound, and the lubricant is deposited on the surface of the object to be deposited which is erected vertically or laid horizontally. As a result, a lubricant layer is formed.
That is, the fluorine-based compound (lubricant composition) polymerized in the gas phase reaches the surface by diffusion, adheres, and is fixed.
This forms a lubricant layer. Since this polymerization reaction proceeds in the gas phase, it is not affected by the non-uniformity of the disk surface, and there is no need to cool the disk to promote surface condensation, resulting in excellent productivity.

In the present invention, the gas phase polymerization means a reaction in which the reactants are kept in the gas phase and the polymerization reaction (particularly, high molecular weight) takes place only in the gas phase. For example, it is performed by plasma polymerization or CVD (in particular, photo CVD). In the case of performing photo CVD, the surface of the object to be precipitated is not directly irradiated with the laser beam, but is irradiated only in the source gas.

The point of the present invention is that a lubricant layer is formed by gas phase polymerization, and the lubricant layer is fixed to the protective layer and the free lubricant molecule is not fixed to the protective layer. The point is that and coexist. For example, CSS with a textured surface that gives a fine surface roughness when no free lubricant molecules are present
The friction coefficient increases in the test, and it does not meet the recent needs. That is, when a lubricant layer was formed only with fixed lubricant molecules whose ends were fixed as proposed in JP-A-6-220185, excellent results could not be obtained in the CSS test.

As in the present invention, a magnetic disk having a mixed lubricant layer composed of a mixture of fixed lubricant molecules and free lubricant molecules formed by gas phase polymerization has a lubricant having a polar group and a lubricant having no polar group. It was found that the CSS test was stable at a high level and showed significantly excellent characteristics as compared with a conventional magnetic disk provided with a mixed lubricant layer containing a lubricant. Moreover, by forming the lubricant layer by vapor phase polymerization, the sliding durability improved by the oxide burnishing is further improved.

The thickness of the lubricant layer, particularly the thickness of the lubricant layer composed of free lubricant molecules, depends on the conditions of the gas phase polymerization process (raw material gas pressure, light irradiation conditions and time) and the gas phase polymerization process. It can be controlled by the number of repetitions.

In the present invention, in particular, the first polymerization step of polymerizing a fluorocarbon compound and oxygen under vacuum conditions to form the lubricant layer, and, after introducing steam, under vacuum conditions. It can be carried out by sequentially performing the second polymerization step of performing vapor phase polymerization to polymerize the fluorocarbon compound and oxygen to form the lubricant layer. Here, the said 1st superposition | polymerization process is a process of mainly forming the said fixed layer, and the said 2nd superposition | polymerization process is a process of mainly forming the said free layer.

That is, the free layer may be formed in the first polymerization step, and the fixed layer may be formed in the second polymerization step.

With respect to the steps other than the formation of the lubricant layer, the same method as the conventionally known method for producing a magnetic recording medium can be adopted without any particular limitation.

First, the gas phase polymerization carried out in the first and second polymerization steps will be described.

The above-mentioned vapor phase polymerization means a polymerization method in which a fluorocarbon compound and oxygen are polymerized in a system in which the gas phase is maintained in a gas state, and the polymerization reaction is caused only in the gas phase. As a method that can be adopted for the polymerization, for example, C such as plasma polymerization or photo CVD (chemical vapor deposition) is used.
Although VD can be adopted, in the present invention, photo-CVD is preferably adopted because the equipment and facilities can be simple.

When polymerization is carried out by the above photo-CVD,
Laser light is deposited on the surface of the object (that is, the surface of the protective layer)
It is preferable to irradiate the raw material gas only and not directly irradiate it.

At this time, examples of the light source that can be used include ultraviolet rays and infrared rays, but it is preferable to use ultraviolet rays for the following reasons. Specifically, for example, excimer laser light of 193 nm is preferably used. You can

That is, since the reaction by the infrared laser using infrared light as the light source is basically a reaction by vibration excitation, it is essentially the same as a thermal reaction, and a side reaction occurs and products other than the target product are generated. It is difficult to control the structure of the formed film.

On the other hand, an ultraviolet laser using an ultraviolet ray as a light source causes a polymerization reaction by electronic excitation and has a good reaction selectivity. Further, since the thermal reaction is extremely low in involvement, a side reaction may occur. Low.

The temperature of the substrate (including the one provided with the protective layer) at the time of carrying out the vapor phase polymerization is 10 to 10.
The temperature is preferably set to 90 ° C, and further 15 to
It is preferably 50 ° C. If it is out of the above range, the lubricating layer may not be formed, so it is preferable to set it in the above range.

Next, the first and second polymerization steps described above will be described more specifically with reference to FIG.

Here, FIG. 1 is a schematic diagram showing a photoreaction chamber that can be used in the method of manufacturing a magnetic recording medium of the present invention.

The photoreaction chamber 1 shown in FIG. 1 is provided with a laser transmission window 2 for transmitting laser light, which is provided on both left and right side surfaces above it, and a magnetic disk substrate 3 as a magnetic recording medium provided below. The medium setting member 4 (provided up to the protective layer) can be set up at regular intervals, and the valve 5 for depressurizing the inside of the chamber and opening to the atmosphere provided at the upper part.

In the first polymerization step, first, the valve 5 is opened, the inside of the chamber 1 is once decompressed by a vacuum pump (not shown) to be evacuated, and then fluorocarbon is added. A system compound and oxygen are introduced to make the above vacuum conditions. Next, excimer laser light or the like is irradiated in the direction of the arrow shown in FIG. 1 so as to pass through the center between the upper part of the magnetic disk substrate 3 and the chamber ceiling and not hit the magnetic disk substrate 3.

Therefore, the above-mentioned vacuum condition means a condition in which the fluorocarbon compound and the oxygen are introduced into the reaction vessel (1 × 10 ^{−6 to} 1 Torr) in a vacuum state, and the atmospheric pressure in this state is 5 It is preferably set to 200 Torr.

The medium mounting member 4 is adapted to rotate each magnetic disk substrate 3 in the circumferential direction. Moreover, the above-mentioned first polymerization step may be repeated several times.

Then, in the second polymerization step, after the completion of the first polymerization step, the valve 5 is opened to return the vacuum condition in the first polymerization step to the atmospheric pressure condition. Then, after introducing water vapor into the chamber 1, the pressure is reduced to a vacuum and then a fluorocarbon compound and oxygen are introduced to make the vacuum condition as described in the first polymerization step. Etc.

The "vacuum conditions" in the second polymerization step are the same as the "vacuum conditions" in the first polymerization step.

Further, in the present invention, the introduction of the water vapor is carried out under the atmospheric pressure condition of the chamber 1 as described above, and it is preferable to introduce the atmosphere, and the atmosphere introduced at this time is preferable. The relative humidity of is preferably 30 to 90%, and more preferably 40 to 80%.
The second polymerization step may also be repeated several times. In addition, after the second polymerization step, the first
It is also possible to carry out the polymerization step.

(C) Others In the method of manufacturing the magnetic recording medium of the present invention, the steps other than the burnishing step by the oxidation treatment and the gas phase polymerization step can be carried out in accordance with the conventional manufacturing method. That is, in the present invention, the basics of the magnetic recording medium are already configured before the step of removing the abnormal protrusion existing on the surface by the oxidation treatment. For example, a step of providing a magnetic layer on a carbon substrate by dry plating means such as vapor deposition or sputtering means,
The magnetic recording medium is configured through the steps of providing a protective layer on the magnetic layer by dry plating means such as vapor deposition or sputtering means, or by dipping or spin coating method. Work is performed to remove the existing abnormal protrusions. Further, before the magnetic layer is provided, a magnetic recording medium is manufactured through a step of providing an underlayer on a carbon substrate by dry plating means such as vapor deposition or sputtering means.

Incidentally, it is preferable to employ dry plating means for film formation. That is, the dry plating means is more likely to obtain a high-quality magnetic film than the wet plating means. Further, the composition of the magnetic film can be easily changed, and the design of the magnetic film can be easily changed.

As described above, the burnishing process of the present invention oxidizes the protective layer by placing the substrate in an oxidizing atmosphere. At this time, the abnormal protrusions are preferentially oxidized and vaporized and removed. To be done. Further, the height (degree of oxidation) of the abnormal projections to be removed can be precisely controlled by adjusting the oxidation conditions (temperature and time). Therefore, in the present invention, any material can be used as the constituent material of the protective layer as long as it can be vaporized and decomposed by oxidation and does not adversely affect the disk manufacturing process at that time. In particular, in the present invention, the protective layer is preferably composed mainly of carbon such as diamond-like carbon, glassy carbon and graphite. These carbon protective layers are
It is formed by a conventionally known method, for example, vapor deposition such as sputtering, and its thickness is about 5 to 25 nm.

Then, through the above steps, the abnormal protrusions left on the surface of the magnetic recording medium are removed. As a result, the flying height of the magnetic head can be reduced and the spacing loss is reduced, which is preferable in terms of reproduction output.

In the present invention, the conventional technology is used as it is for the structure of the magnetic layer on the substrate. That is, as for the structure of the underlayer (underlayer film), the magnetic layer (magnetic film), the protective layer (protective film) and the like provided on the substrate, the conventional technique can be used as it is. For example, Japanese Patent Laid-Open No. 5-1
The techniques described in Japanese Patent Application Laid-Open No. 8952, Japanese Patent Application Laid-Open No. 5-137822, Japanese Patent Application Laid-Open No. 5-212769, and Japanese Patent Application Laid-Open No. 5-289494 can be used.

The substrate used in the present invention comprises, for example, carbon such as glassy carbon, tempered glass, crystallized glass, aluminum and aluminum alloys, titanium and titanium alloys, ceramics, resins, or composite materials thereof. Is mentioned. Among these, glassy carbon is particularly preferable, and for example, those described in JP-A-60-35333 can be used.

In the method for manufacturing a magnetic recording medium of the present invention, the oxide burnishing step can be carried out continuously with the formation of the magnetic layer and the protective layer. Further, the gas phase polymerization step can be continuously performed with the formation of the magnetic layer and the protective layer and the oxidation burnishing step. For example, the oxidation treatment and / or the vapor-phase polymerization reaction can be performed in the same production line in which the magnetic layer and the protective layer are formed, in the same film-forming chamber whose interior is defined. Further, both the burnishing step and the vapor phase polymerization step can be performed in vacuum, and the burnishing step and / or the vapor phase polymerization step can be performed in the same vacuum system after the formation of the magnetic layer and the protective layer by dry plating such as vapor deposition. Therefore, since the film forming process (magnetic layer → protective layer) and burnishing process, which are the main manufacturing processes of the magnetic disk, can be performed in the same film forming chamber, it is possible to improve the productivity in terms of the device and the process. Become.

[0058]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 8 and Comparative Examples 1 to 3 Film forming step As a substrate, (1) a glassy carbon substrate having a diameter of 1.8 inches, 25 mils and a specific gravity of 1.5 (indicated as "GC" in the table) (2) A glass substrate (tempered glass or crystalline glass) of the same size as the substrate (1) was prepared. The substrates used are shown in Tables 1 to 3.

Ar gas pressure of 2 mTor was applied on these substrates.
A Ti layer having a thickness of 100 nm was formed by DC magnetron sputtering under the conditions of r and the substrate temperature of 250 ° C. Then, a 20 nm-thick Al-Si alloy (Al: Si = 10 :) was deposited on the Ti layer by DC magnetron sputtering under the conditions of Ar gas pressure of 2 mTorr and substrate temperature of 260 ° C.
90 / wt%) layer was formed. These layers form unevenness (texture) on the substrate.

Next, an amorphous carbon (diamond-like carbon) layer having a thickness of 25 nm was formed on the Al-Si alloy layer by DC magnetron sputtering under the conditions of Ar gas pressure of 2 mTorr and substrate temperature of 260 ° C. Next, Ar gas pressure 2 mTorr, substrate temperature 20
Using a DC magnetron sputtering device under the condition of 0 ° C., a thickness of 100 nm is formed on the amorphous carbon layer.
A Ti layer of 40 nm thick, and then a 40 nm thick C layer is formed on the Ti layer.
An r layer was provided.

Further, a 400 nm-thick Co-Cr-Pt layer was formed on the Cr layer by DC magnetron sputtering under the conditions of Ar gas pressure of 2 mTorr and substrate temperature of 260 ° C.
A -B type magnetic layer was provided.

Subsequently, the interior of the chamber was evacuated using a facing target type sputtering apparatus equipped with a glassy carbon target, and Ar was adjusted to a gas pressure of 2 mTorr.
A gas was introduced to perform sputtering, and a protective layer made of amorphous carbon (diamond-like carbon) having a thickness of 20 nm was provided on the magnetic layer.

Burnishing Process The substrates on which various films were formed as described above were burnished under the conditions shown in Tables 1 to 3. The burnishing process of each example was carried out in the same chamber (the inside is defined) as the film forming process described above. The tape burnish of Comparative Example 1 was carried out by pressing the polishing tape against a rotating roll with a rubber roll, under the following conditions. Abrasive tape: WA # 10000 Relative speed: 100 m / sec Time: 1 sec Roll hardness: 25 Shore hardness Roll pressing pressure: 0.8 kgf Further, in Comparative Example 2 and Comparative Example 1 except that WA # 8000 was used as the abrasive tape. In the same manner, Comparative Example 3 did not carry out the burnishing treatment.

Gas Phase Polymerization Step Using the magnetic disk substrate 3 thus obtained, as shown in FIG. 1, a chamber 1 for photoreaction, which is a CVD device, is arranged in parallel at a predetermined interval as shown in FIG. After arranging and evacuating the chamber 1 to 5 × 10 ^-2 Torr, CF ₂ = C
FCF ₃ 10 Torr and oxygen 60 Torr were introduced,
12. Laser light (power 150 mJ, repetition rate 2 Hz) from ArF excimer laser (wavelength 193 nm) was used.
The first polymerization step was performed once by irradiating 1500 pulses for 5 minutes. After this, the chamber 1 is leaked and the humidity 6
Atmospheric conditions were introduced by introducing 0% air. After this, again
After evacuating the chamber 1 to 5 × 10 ^-2 Torr, C
F ₂ = CFCF ₃ 10 Torr and oxygen 60 Torr were introduced, and the laser beam was irradiated for 1500 pulses over 12.5 minutes, and the second polymerization step was performed twice. The laser light was irradiated in the direction of the arrow shown in FIG. 1 so that the magnetic disk substrate 3 was not directly irradiated with the laser light. The temperature of the magnetic disk substrate 3 was room temperature (22 ° C.) during the photo-CVD.

Examples 2 to 8 were similarly performed under the conditions shown in Tables 1 and 2. In Comparative Examples 1 to 3, the lubricant layer was formed by applying a solution of a perfluoropolyether lubricant (Fomblin AM2001 manufactured by Montecatini Co., Ltd.) so that the thickness after drying was 25 Å.

Characteristic Evaluation The magnetic disk obtained as described above was evaluated for the following characteristics. The results are shown in Tables 1 to 3.

(I) Rp (center line maximum height) Rp is a stylus roughness meter (manufactured by TENCOR, model P
According to 2), it measured on the following conditions. Stylus diameter: 0.6 μm (needle curvature radius) Stylus pressing pressure: 7 mg Measurement length: 250 μm x 8 places Trace speed: 2.5 μm / sec Cut-off: 1.25 μm (low pass filter) (ii) Appearance inspection Bright illumination Visual inspection was performed under the following conditions to check for scratches and scratches, and those having an appearance with no problem in practical use were regarded as acceptable and evaluated according to the following criteria. S: Pass rate is 80% or more to 100% A: Pass rate is 50% to less than 80% B: Pass rate is 30% to less than 50% C: Pass rate is 0% to less than 30% (iii) It was performed using a MG150T device manufactured by GHT Proquip, using a 50% slider head. The following evaluation was made based on the passing rate at a flying height of 1.3 μ inches. S: Passage is 90% or more A: Passage is 70% or more and less than 90% B: Passage is 50% or more and less than 70% C: Passage is 30% or more and less than 50% D: Passage is 30 Less than% (iv) MCF (error characteristic) The error characteristic was measured using a MG150T device manufactured by Proquip, using a 70% slider head, and a recording density of 51 KF.
It was evaluated under the condition of CZ. Slice level is 70%,
The number of missing errors of less than 16 bits was counted and evaluated as follows. S: 50% or more of the evaluation disks have 0 to 5 errors. A: The number of errors is 6 to 15 in 50% or more of the evaluation disks
Individual. B: The number of errors is 16 to 4 in 50% or more of the evaluation disks
There are five. C: 50% or more of the evaluation disks have 46 or more errors.

(V) CSS Using a thin film head manufactured by Yamaha Corporation, head load 3.5 g,
A cycle in which the head flying height was 2.8 μ inches, operating at 4500 rpm for 5 seconds and stopping for 5 seconds was repeated, and the number of times until the static friction coefficient (μs) reached 0.6 was examined.

[0070]

[Table 1]

[0071]

[Table 2]

[0072]

[Table 3]

Note) In Tables 1 to 3 above, X ₁ and X ₂ are the following compounds. X ₁ ; Tetrafluoroethylene X ₂ ; Hexafluoroethylene As can be seen from these results, in the magnetic recording medium according to the production method of the present invention, the abnormal protrusions on the surface are effectively removed, and the error hardly occurs. You can see that it has become a thing. It is also apparent that the magnetic recording medium manufactured by the manufacturing method of the present invention has markedly improved CSS characteristics and improved sliding durability.

[0074]

According to the manufacturing method of the present invention, abnormal protrusions on the surface of a magnetic recording medium can be effectively removed, the certifying (error) yield is improved, and the appearance defect is significantly reduced. Further, since a plurality of burnishing processes can be continuously performed and the burnishing process can be performed by a relatively inexpensive device, the productivity is dramatically improved. Moreover, the manufactured magnetic disk has the effects of improving the sliding durability with the head, suppressing the adsorption of the head, and the like. In particular, the effect of improving sliding durability is maintained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a main part of a CVD apparatus used in a manufacturing method of the present invention.

[Explanation of symbols]

 1 Chamber 2 Laser Transmission Window 3 Magnetic Disk Substrate 4 Medium Setting Member 5 Valve

Claims (12)

[Claims] 1. At least a step of forming a magnetic layer on a non-magnetic substrate, a step of forming a protective layer on the magnetic layer, and a burnishing step of reducing the height of abnormal protrusions present on the surface of the protective layer. In the method for manufacturing a magnetic recording medium having a step of forming a lubricant layer on the protective layer, the burnishing step is performed by an oxidation treatment, and the formation of the lubricant layer is performed by gas phase polymerization under vacuum conditions. A method for manufacturing a magnetic recording medium, which is characterized by being performed. 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein the oxidation treatment is thermal oxidation. 3. The method for producing a magnetic recording medium according to claim 1, wherein the main constituent component of the protective layer is carbon. 4. The method for producing a magnetic recording medium according to claim 1, wherein the protective layer forming step and the burnishing step are continuously performed. 5. The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic layer forming step, the protective layer forming step and the burnishing step are continuously performed. 6. The vapor phase polymerization step comprises a first polymerization step of polymerizing a fluorocarbon compound and oxygen to form a lubricant layer, and a vapor phase polymerization after introducing steam. 6. The magnetic recording medium according to claim 1, wherein the second polymerization step of forming a lubricant layer by polymerizing a fluorocarbon compound and oxygen is sequentially performed. Production method. 7. The method for producing a magnetic recording medium according to claim 6, wherein the introduction of the water vapor is performed by returning the vacuum condition in the first polymerization step to an atmospheric pressure condition after the completion of the first polymerization step. 8. The method for producing a magnetic recording medium according to claim 1, wherein the gas phase polymerization is carried out at a temperature of 10 to 90 ° C. 9. The method for manufacturing a magnetic recording medium according to claim 1, wherein the gas phase polymerization is performed by irradiating a mixed gas of a fluorocarbon compound and oxygen with an ultraviolet laser. 10. The method for manufacturing a magnetic recording medium according to claim 1, wherein the vapor phase polymerization is performed by CVD. 11. The method for manufacturing a magnetic recording medium according to claim 1, wherein the vapor phase polymerization is performed by photo-CVD. 12. The ratio (molar ratio) of the fluorocarbon compound and oxygen is fluorocarbon system / oxygen = 1 / 0.5 to 1.
The method of manufacturing a magnetic recording medium according to claim 6, wherein the magnetic recording medium is / 100.