JP2002319126A - Method for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium, capable of making a lubricant layer uniform within a short time after the formation of a magnetization pattern, and carrying out incorporation into a drive, inspection/evaluation, or the like in a short time. SOLUTION: In the manufacturing method of a magnetic recording medium having a magnetization pattern, in which after the formation of at least a magnetic layer and a lubricant layer on a substrate, the magnetization pattern is formed on the magnetic layer in an external magnetic field application step and a local heating step, after the formation of the magnetization pattern, a uniformizing operation is executed to make the characteristics of the lubricant layer uniform. As the uniformizing operation, heating of the full surface of the lubricant layer is suitable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a magnetic recording medium such as a magnetic disk used in a magnetic recording apparatus.

[Prior art]

A magnetic recording device represented by a magnetic disk device (hard disk drive) is widely used as an external storage device of an information processing device such as a computer. In recent years, a magnetic recording device has been used as a video recording device or a recording device for a set-top box. Are also being used.

[0003] A magnetic disk device usually includes a shaft for fixing one or more magnetic disks in a skewered manner,
A motor for rotating a magnetic disk joined to the shaft via a bearing, a magnetic head used for recording and / or reproduction, an arm to which the head is attached, and a head on the magnetic recording medium via the head arm And an actuator that can be moved to any position. The recording / reproducing head is usually a floating head, and moves on a magnetic recording medium at a constant flying height.

In addition to a floating head, a contact head (contact type head) is used to further reduce the distance from a medium.
The use of has also been proposed.

A magnetic recording medium mounted on a magnetic disk device generally has a NiP layer formed on the surface of a substrate made of an aluminum alloy or the like, performs a required smoothing process, a texturing process, and the like. It is manufactured by sequentially forming a metal base layer, a magnetic layer (information recording layer), a protective layer, a lubricating layer, and the like. A glass substrate is used in place of the aluminum alloy substrate, and a metal base layer, a magnetic layer (information recording layer), a protective layer, a lubricating layer, and the like are sequentially formed on the surface of the glass substrate. Magnetic recording media include in-plane magnetic recording media and perpendicular magnetic recording media. In the longitudinal magnetic recording medium, longitudinal recording is usually performed.

In order to increase the recording density of a magnetic recording medium,
Improvements such as reducing the flying height of the magnetic head, adopting a GMR head as the magnetic head, increasing the magnetic material used for the recording layer of the magnetic disk to have a high coercive force, and improving the information recording track of the magnetic disk Attempts have been made to reduce the spacing. For example, 100Gbit / inc
To achieve h ^2, the track density is required than 100Ktpi.

[0007] Each track records a control magnetization pattern for controlling the magnetic head, for example, a signal used for position control of the magnetic head.

When the number of tracks is increased by reducing the interval between information recording tracks for higher density, a signal used for position control of a data recording / reproducing head (hereinafter, may be referred to as a "servo signal"). Accordingly, it must be provided densely in the radial direction of the disk, that is, more, so that precise control can be performed.

Further, in order to increase the data recording area by reducing the area other than the area used for data recording, that is, the area used for the servo signal and the gap between the servo area and the data recording area, to increase the data recording capacity. In this case, it is necessary to increase the output of the servo signal and the accuracy of the synchronization signal.

Conventionally, a method widely used for recording a servo signal is to make a hole near the head actuator of a drive (magnetic recording device), insert a pin with an encoder into the hole, and engage the actuator with the pin. Then, the head is driven to an accurate position to record a servo signal. However, since the center of gravity of the positioning mechanism is different from the center of gravity of the actuator, highly accurate track position control cannot be performed, and it has been difficult to accurately record servo signals.

On the other hand, there has also been proposed a technique of forming an uneven servo signal by irradiating a magnetic disk with a laser beam to locally deform the disk surface to form physical unevenness. However, the unevenness makes the flying head unstable and adversely affects recording and reproduction; it is necessary to use a laser beam having a large power to form the unevenness, which is costly; it takes time to form the unevenness one by one; There was such a problem.

As still another method of forming a servo signal, a servo pattern is formed on a master disk having a magnetic layer with a high coercive force, the master disk is brought into close contact with a magnetic recording medium, and an external auxiliary magnetic field is applied to transfer the magnetization pattern. (US Pat. No. 5,991,104).

Further, the medium is magnetized in one direction in advance,
There is also known a method in which a soft magnetic layer or the like having a high magnetic permeability and a low coercive force is patterned on a master disk to bring the master disk into close contact with a medium and apply an external magnetic field. In this method, the soft magnetic layer acts as a shield, and a magnetization pattern is transferred to an unshielded area (Japanese Patent Laid-Open No. 50-19764).
No. 602212 (USP 3,869,711),
JP-A-10-45544 (EP 915456)
No.), Digest of InterMag 2000, GP-06).

In these methods, a magnetic pattern is formed on a medium by a strong magnetic field using a master disk. However, the strength of the magnetic field generally depends on the distance. Also, the pattern boundary is likely to be unclear due to the leakage magnetic field. Therefore, in this method, it is indispensable to bring the master disk and the medium into close contact in order to minimize the leakage magnetic field. As the pattern becomes finer, it is necessary to make the pattern adhere to each other without any gap.

Further, the higher the coercive force of the medium, the larger the magnetic field used for transfer and the larger the leakage magnetic field.
Further, it is necessary to adhere sufficiently. Therefore, these methods are easy to apply to a magnetic disk having a low coercive force and a flexible floppy (registered trademark) disk which is easily pressed, but a coercive force for high-density recording using a hard substrate is 300.
It is very difficult to apply it to a magnetic disk having more than 0 Oe.

That is, a magnetic disk having a hard substrate may have a problem that a small dust or the like may be interposed between the magnetic disks when the magnetic disk is brought into close contact, causing a defect in the medium or damaging an expensive master disk. In particular, in the case of a glass substrate, there has been a problem that the adhesion is insufficient due to the interposition of dust, magnetic transfer cannot be performed, and cracks are generated on the magnetic recording medium.

Further, Japanese Patent Laid-Open No. 50-60212 (U.S. Pat.
In the method described in Japanese Patent Application Laid-Open No. SP3,869,711), there is a problem that a pattern having an oblique angle with respect to the track direction of a disc can be recorded but only a pattern having a weak signal intensity can be formed. Coercivity is 2000-2
For a magnetic recording medium having a high coercive force of 500 Oe or more,
In order to secure the magnetic field strength of the transfer, a soft magnetic material having a large saturation magnetic flux density such as permalloy or sendust must be used as the pattern ferromagnetic material (shield material) of the master disk.

However, in the oblique pattern, the magnetic field of the magnetization reversal is in a direction perpendicular to the gap formed by the ferromagnetic layer of the master disk, and the magnetization cannot be inclined in a desired direction. As a result, a part of the magnetic field escapes to the ferromagnetic layer, so that it is difficult to apply a sufficient magnetic field to a desired portion during magnetic transfer, and it is not possible to form a sufficient magnetization reversal pattern and to obtain a high signal strength. With such an oblique magnetization pattern, the reproduction output is greatly reduced more than the azimuth loss with respect to the pattern perpendicular to the track.

Therefore, the present applicant has filed Japanese Patent Application No. 2000-13.
No. 4608 and Japanese Patent Application No. 2000-134611 propose a method of forming a magnetization pattern on a magnetic recording medium by combining local heating and application of an external magnetic field. For example, the medium is magnetized in one direction in advance, and is locally heated by irradiating an energy ray or the like through a patterned mask, applying an external magnetic field while lowering the coercive force of the heated area, and applying a magnetic field to the heated area. Recording by an external magnetic field is performed to form a magnetization pattern.

According to this method, since the external magnetic field is applied by lowering the coercive force by heating, the external magnetic field does not need to be higher than the coercive force of the medium, and recording can be performed with a weak magnetic field. Then, the area to be recorded is limited to the heated area, and the area other than the heated area is not recorded even when a magnetic field is applied. Therefore, a clear magnetization pattern can be recorded without bringing a mask or the like into close contact with the medium. For this reason, the medium and the mask are not damaged by the pressure bonding, and the defect of the medium is not increased.

Further, according to this method, an oblique magnetization pattern can be formed well. This is because there is no need to shield the external magnetic field with the soft magnetic material of the master disk as in the related art.

[0022]

SUMMARY OF THE INVENTION As described above, Japanese Patent Application No.
The method of forming a magnetic pattern described in JP-A-00-134608 and JP-A-134611 can form various fine magnetic patterns efficiently and accurately, and does not damage the medium or the mask and does not increase the defect of the medium. It is.

In this method, in order to form a magnetization pattern on a magnetic recording medium having a particularly high coercive force, it is necessary to increase the temperature of local heating or increase the external magnetic field. Increasing the external magnetic field increases the possibility of unintentionally magnetizing a region that is not locally heated. Therefore, it is preferable to increase the temperature of local heating. For example, when heating by energy ray irradiation, the heating temperature is increased by increasing the energy density (power, intensity).

However, as a result of various studies, it has been found that when the heating temperature of the local heating is increased, the contamination of the magnetic head by the lubricant increases, and stiction and friction tend to increase.

This tendency gradually disappears with time after pattern formation. However, the longer the time is taken during manufacturing, the easier it is for dust and particles to adhere. In addition, in order to reduce the manufacturing cost, it is desirable to keep the process continuous without taking time between processes.

According to the present invention, it is possible to manufacture a magnetic recording medium in which a lubricating layer can be made uniform in a short time after the formation of a magnetic pattern, and can be incorporated into a drive, inspected, evaluated, etc. without time. The aim is to provide a method.

[0027]

According to a method of manufacturing a magnetic recording medium of the present invention, a magnetic layer is formed on a substrate, a lubricating layer is formed, and a magnetic pattern is formed by an external magnetic field applying step and a local heating step. The method for manufacturing a magnetic recording medium with a magnetized pattern for forming a pattern, characterized in that, after the pattern is formed, a uniformizing process for uniformizing properties of the lubricating layer is performed.

By performing such a lubricating layer homogenization process, it is possible to make the film thickness distribution of the lubricating layer uniform and the distribution of low molecular weight components uniform as compared with before the homogenization process. That is, it is possible to increase (recover) the film thickness of the local heating region whose film thickness has decreased in the preceding magnetization pattern forming step. Further, the distribution of low molecular weight components in the lubricating layer can be made uniform.

In the process of forming a magnetic pattern on a magnetic recording medium by applying an external magnetic field and local heating, the inventors of the present invention have found that if the heating temperature for local heating is increased, contamination of the magnetic head with a lubricant increases, and stiction, It has been found that friction tends to increase. This is probably because a difference occurs in the thickness of the lubricating layer between the heated portion and the non-heated portion due to local heating, or a low molecular weight component in the lubricating layer migrates to the lubricating layer surface and is unevenly distributed on the surface It is presumed that it is.

When the magnetic recording medium immediately after the formation of the magnetization pattern in which the distribution of the thickness and the low molecular weight component becomes non-uniform is directly incorporated in the drive, the lubricant is sucked into the magnetic head from the thickened portion of the lubricating layer. It is considered that there is a possibility that the ink may adhere to the head to cause contamination, and that stiction and friction may easily increase. If the low molecular weight component is large on the surface, adhesion to the magnetic head is more likely to occur.

Further, when inspection / evaluation using a magnetic head is performed after pattern formation, the magnetic head is stained, and stiction and friction are likely to increase.

Therefore, in the present invention, by performing a homogenizing step after forming the magnetic pattern, the thickness of the lubricating layer,
Uniform distribution of low molecular weight components.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The magnetic recording medium manufactured according to the present invention has a substrate, and a magnetic layer and a lubricating layer formed on the substrate. Usually, on this substrate, a metal underlayer, a magnetic layer (information recording layer), a protective layer, and a lubricating layer are formed in this order.

The method of the present invention is characterized in that a lubricating layer is homogenized after forming a magnetization pattern by applying an external magnetic field and a local heating process. First, the lubricating layer and the homogenizing process will be described. I do.

First, the lubricating layer will be described.

The formation of the lubricating layer is generally performed by applying a lubricant, and an arbitrary coating process such as a spin coating method, a pull-up coating method, and a spray coating method is used. In order to uniformly form a lubricating layer on a large amount of medium in a short time, a pull-up coating method is suitable.

As the lubricant, perfluoropolyether having an ester bond, dialkylamide carboxylic acid, perchloropolyether, stearic acid, sodium stearate, phosphate ester and the like are preferable. The ester bond may be located anywhere in the molecule, but it is more preferable to have an ester bond functional group at the end, since the movable portion in the molecule becomes longer and lubricity is easily obtained.

In particular, in the main chain, a —C _k F _2k O— unit (provided that
k is an integer of 1 to 4), and a perfluoropolyether having a terminal functional group of an ester bond is preferable. More preferred are perfluoroethers represented by the following general formula (I). R-O- (A'-O- A '' - O) x-R (I) ( provided that, A ', A''is composed of CF ₂ and / or _C 2 _{F 4,} respectively, A' and A CF ₂ constituting ''
And the ratio of C ₂ F ₄ (CF ₂ / C ₂ F ₄ ) is 5/1 to 1 /
5, X represents 10 to 500, and R represents an alkyl group having 1 to 20 carbon atoms containing a hetero atom or a fluorine-substituted alkyl group. )

For example, Fomblin manufactured by Ausimont Co., Ltd.
-Z-DOL is a polymer of CF ₂ CF ₂ O and CF ₂ O and has a linear structure, and has an ester group —COOR (both in which
R represents an alkyl group which may be substituted by fluorine. ). In addition, demnum manufactured by Daikin Industries, Ltd.
The type (SP or SY) is a homopolymer of hexafluoropropylene oxide, and has an ester group -CO at one end.
OR (where R represents an alkyl group which may be substituted with fluorine).

The number average molecular weight of the lubricant is 100 to 1000
It is preferably within the range of 0. More preferably, the number average molecular weight is from 2,000 to 6,000. If the molecular weight is low, the vapor pressure is generally high, evaporates little by little after coating, and moves away from the desired film thickness with time. Conversely, when the molecular weight is high, the viscosity is generally high, and the desired lubricity may not be obtained.

Preferably, Fombl manufactured by Ausimont is used.
in-Z-DOL (trade name), Fomblin-ZT
Etraol (trade name) or the like is used.

Further, additives such as X-1P manufactured by Dow Chemical may be added to improve durability.

As a solvent for dissolving these, for example, fluorocarbons, alcohols, hydrocarbons, ketones,
Ether type, fluorine type, aromatic type and the like are used.

In order to increase the chemical bond between the lubricant and the medium,
It is preferable to perform a heat treatment (firing) after the formation of the lubricating layer.
The firing temperature is 50 ° C. or higher, but may be appropriately selected within a range lower than the decomposition temperature of the lubricant. Firing temperature is 1
The temperature is preferably 50 ° C or lower, and usually 100 ° C or lower.

The thickness of the lubricating layer is preferably 10 nm or less. Even if the thickness is too large, lubricity of a certain level or more cannot be obtained, and excess lubricant moves to the outer peripheral side with the rotation of the disk, and the film thickness distribution at the inner and outer peripheries tends to occur. However, if the thickness is too small, desired lubricity cannot be obtained, so that the thickness is preferably 0.5 nm or more. More preferably, it is 1 nm or more.

Next, the equalizing process will be described.

As described above, in the lubricating layer formed as described above, when heated by a laser or the like at the time of forming a magnetic pattern, the rise of the temperature of the irradiated portion causes the low molecular components to float (to the surface). Concentration) and a film thickness distribution.

By subjecting the lubricating layer to a uniform treatment according to the method of the present invention, the thickness of the lubricating layer is made uniform and the distribution of low molecular weight components is made uniform. As described above, the higher the coercive force of the medium, the higher the local heating temperature at the time of forming the magnetization pattern, and the more uneven the lubricating layer is likely to progress. In the present invention, such a coercive force is, for example, 3000 Oe.
The above is particularly effective when applied to particularly high media.

Specific examples of the homogenizing treatment include heating, for example, heating by laser irradiation, heating by an oven, and heating by an infrared lamp.

The heating increases the fluidity of the lubricant,
It is considered that the properties of the lubricating layer become uniform. This heat treatment is preferable because it does not physically come into contact with the magnetic recording medium, so that it is considered that adhesion of dust or the like hardly occurs.

In the case of laser irradiation, a laser is irradiated on the entire surface of the medium. It is preferable to use a light shielding plate in order to prevent laser beams from overlapping.

The energy density of the laser beam is 30 to
200 mJ / cm ^2, particularly 50~150mJ / cm ² is preferred. According to the laser irradiation, in addition to the heating effect, the laser cleaning effect (the surface of the lubricating layer expands due to the rapid rise in temperature due to the laser irradiation, and the acceleration of the lubricating layer causes materials with weak adsorption power to adhere to the surface. (Eg, low molecular weight components of the lubricant are removed).

The preferred temperature range of the laser heat treatment is a temperature range in which the lubricant easily flows below the temperature at which the thermal decomposition of the lubricant does not start.
00 ° C, particularly 110-170 ° C, is preferred.

In order to perform heating by an oven, an air circulation type drier having a filter of 0.3 μm or less in an outside air intake is used, the temperature in the drier layer is adjusted to a predetermined temperature, and the medium is made of stainless steel. In a state of being housed in a cassette, it is placed in a dryer and heated for a predetermined time. The preferable heating temperature range is the same as the case of the heating by the laser. The heating time is preferably 30 seconds to 30 minutes, particularly preferably about 1 to 20 minutes.

In the heating method using an infrared lamp, the entire surface of the medium is heated with an infrared lamp. The preferable heating temperature range is the same as the case of the heating by the laser. The heating time is preferably 30 seconds to 30 minutes, particularly preferably about 1 to 20 minutes.

As a specific method of heating with an infrared lamp, there is a method of heating a quartz glass dome in which an infrared lamp is arranged along a side surface by feeding a medium at a predetermined speed while facing the infrared lamp. Can be

As a heating method, in the case of a medium containing metal, an eddy current is generated in the medium and the medium is heated by current induction, or a terminal is brought into contact with a lubricating layer on the medium.
A method of increasing the surface temperature by applying ultrasonic waves can also be adopted.

As a process for homogenizing the lubricating layer, a process for wiping the lubricating layer may be employed in addition to the above heat treatment. For example, a non-woven or woven tape wound on a reel is run, and a medium is pressed against the tape.

It is to be noted that dust or particles may adhere to the medium surface by performing such a uniforming process. Therefore, a surface cleaning treatment may be performed by the following dry ice cleaning, air blowing, head cleaning method, or the like.

In dry ice cleaning, particles and dust on the substrate surface are removed by spraying powdery dry ice by adding nitrogen gas to liquefied carbon dioxide gas through a nozzle onto the medium surface.

In the air blow, dust or particles are removed by blowing air or an inert gas (such as nitrogen) from a nozzle onto a medium surface at a predetermined pressure.

In the head cleaning method, a waffle pad is attached to the tip of a magnetic head, and dust and particles are removed by bringing the pad into contact with a rotating medium.

Next, a description will be given of a substrate of a magnetic recording medium, other film configurations, a method of forming the same, and a method of forming a magnetic pattern.

As the substrate in the magnetic recording medium of the present invention, it is necessary that the substrate does not vibrate even when rotated at high speed during high-speed recording / reproducing. Usually, a hard substrate is used. In order to obtain sufficient rigidity without vibration, the thickness of the substrate is generally preferably 0.3 mm or more. However, if it is thick, it is disadvantageous for thinning the magnetic recording device, so that it is preferably 3 mm or less. For example, an Al alloy substrate containing Al as a main component, such as an Al-Mg alloy, a Mg alloy substrate containing Mg as a main component, such as an Mg-Zn alloy, ordinary soda glass, aluminosilicate glass, or amorphous glass And a substrate made of any one of silicon, titanium, ceramics, and various resins, and a substrate obtained by combining them. Among them, it is preferable to use an Al alloy substrate or a glass substrate such as crystallized glass in terms of strength, and a resin substrate in terms of cost.

The present invention is highly effective when applied to a medium having a hard substrate. In the conventional magnetic transfer method, a medium having a hard substrate has insufficient adhesion to a master disk, causing scratches or defects, and the boundaries of transferred magnetic domains are unclear, and PW5
However, in the present invention, there is no such problem because the mask and the medium are not pressed. In particular,
This is effective for a medium having a substrate that is easily cracked, such as a glass substrate.

In the manufacturing process of the magnetic recording medium, the substrate is usually washed and dried first. In the present invention, from the viewpoint of ensuring the adhesion of each layer, washing and drying are performed before the formation. It is desirable.

In manufacturing the magnetic recording medium of the present invention,
A hard layer such as NiP or NiAl may be formed on the substrate surface.

As a method for forming the hard layer, a method used for forming a thin film, such as an electroless plating method, a sputtering method, a vacuum evaporation method, and a CVD method, can be used. In the case of a substrate made of a conductive material, it is possible to use electrolytic plating. The thickness of the hard layer is preferably 50 nm or more. However, in consideration of the productivity of the magnetic disk medium and the like, the thickness is preferably 20 μm or less. More preferably, it is 10 μm or less.

The region where the hard layer is formed is desirably the entire region of the substrate surface, but it is also possible to implement only a part, for example, only the region where texturing is to be performed.

Further, concentric texturing may be applied to the surface of the substrate or the surface on which the hard layer is formed.
Concentric texturing is, for example, mechanical texturing using loose abrasive grains and texture tape, texturing using a laser beam, or the like, or by using them together, by polishing in the circumferential direction, thereby polishing the substrate in the circumferential direction. To form a large number of microgrooves.

In general, mechanical texturing is performed to obtain in-plane anisotropy of the magnetic layer. If it is desired to form an in-plane isotropic magnetic layer, it is not necessary to perform this step.

Generally, texturing using a laser beam or the like is performed by CSS (contact start
And stop) to improve the characteristics.
When the magnetic disk device is of a system (load / unload system) in which the head is retracted outside the disk when the magnetic disk device is not driven, there is no need to apply this method.

As abrasive grains used for mechanical texturing, alumina abrasive grains are widely used. In particular, from the viewpoint of an in-plane orientation medium in which an axis of easy magnetization is oriented along a texturing groove. Diamond abrasives perform very well. Among them, a diamond abrasive of a bicrystal or single crystal whose surface is graphitized is most preferable.

It is effective that the head flying height is as small as possible to realize high-density magnetic recording, and one of the features of these substrates is excellent surface smoothness. Therefore, the roughness Ra of the substrate surface is 2 nm or less. And more preferably 1 nm or less. Particularly, the thickness is preferably 0.5 nm or less.
The substrate surface roughness Ra is a value calculated according to JIS B0601 after measuring with a stylus type surface roughness meter at a measurement length of 400 μm. At this time, the tip of the measuring needle has a radius of about 0.2 μm.

Next, an underlayer or the like may be formed between the magnetic layer and the substrate. The underlayer aims at miniaturizing the crystal of the recording layer and controlling the orientation of the crystal plane,
Those containing Cr as a main component are preferably used.

The material of the underlayer containing Cr as a main component may be V, Ti, Mo, Zr, Hf, Ta, W, or Cr, for the purpose of crystal matching with the recording layer, in addition to pure Cr.
An alloy containing one or more elements selected from Ge, Nb, Si, Cu, and B, and Cr oxide are also included.

Among them, pure Cr, or Cr, Ti, Mo,
An alloy to which one or more elements selected from W, V, Ta, Si, Nb, Zr and Hf are added is preferable. The optimum content of the second and third elements differs depending on the respective elements, but is generally preferably 1 to 50 atomic%, more preferably 5 to 30 atomic%, and still more preferably 5 to 30 atomic%. % To 20 atomic%.

The film thickness of the underlayer may be sufficient if it can express this anisotropy, but is preferably 0.1 to 50.
nm, more preferably 0.3 to 30 nm, even more preferably 0.5 to 10 nm. The substrate may or may not be heated during the formation of the underlayer mainly composed of Cr.

On the underlayer, a soft magnetic layer may be provided between the recording layer and the underlayer in some cases. In particular, a keeper medium having less magnetization transition noise or a perpendicular recording medium having magnetic domains perpendicular to the plane of the medium has a large effect and is preferably used.

The soft magnetic layer may have a relatively high magnetic permeability and a small loss, but NiFe or an alloy to which Mo or the like is added as the third element is preferably used. Although the optimum magnetic permeability greatly varies depending on the characteristics of the head and the recording layer used for recording data, it is generally preferable that the maximum magnetic permeability is about 10 to 1,000,000 (H / m).

If necessary, an intermediate layer may be provided on the underlayer mainly composed of Cr. For example, it is preferable to provide a CoCr-based intermediate layer because the crystal orientation of the magnetic layer can be easily controlled.

Next, a recording layer (magnetic layer) is formed. A layer of the same material as the underlayer or another non-magnetic material may be inserted between the recording layer and the soft magnetic layer. When forming the recording layer,
Substrate heating may or may not be performed. As the recording layer, a Co alloy magnetic layer, a rare earth magnetic layer represented by TbFeCo, a transition metal / noble metal laminated film represented by a laminated film of Co and Pd, and the like are preferably used.

As the Co alloy magnetic layer, pure Co, CoNi, CoSm, CoCrTa, CoNiCr, C
Co, commonly used as a magnetic material such as oCrPt
Alloy magnetic materials can be used. These Co alloys are further added with N
Elements to which i, Cr, Pt, Ta, W, B or the like, or compounds such as SiO ₂ may be added. For example, CoCrPtT
a, CoCrPtB, CoNiPt, CoNiCrPt
B and the like. The thickness of the Co alloy magnetic layer is arbitrary, but is preferably 5 nm or more, more preferably 10 nm or more, preferably 50 nm or less, more preferably 3 nm or less.
0 nm or less. The recording layer may be formed by laminating two or more layers via an appropriate non-magnetic intermediate layer or directly.
At that time, the composition of the magnetic materials to be laminated may be the same or different.

As the rare earth magnetic layer, a general magnetic material can be used. For example, TbFeCo, Gd
Examples include FeCo, DyFeCo, and TbFe.
Tb, Dy, Ho or the like may be added to these rare earth alloys. Ti, Al, and Pt may be added for the purpose of preventing oxidative deterioration. The thickness of the rare earth magnetic layer is arbitrary, but is usually about 5 to 100 nm. The recording layer may be formed by laminating two or more layers via an appropriate non-magnetic intermediate layer or directly. At that time, the composition of the magnetic materials to be laminated may be the same or different. In particular, the rare-earth magnetic layer is an amorphous structure film and has magnetization in the direction perpendicular to the media plane, so that it is suitable for high recording density recording, and the method of the present invention that can form a magnetization pattern with high density and high accuracy is required. Can be applied more effectively.

Similarly, as a laminated film of a transition metal and a noble metal, which can perform perpendicular magnetic recording, a general magnetic material can be used. For example, Co / Pd, Co / Pt, Fe
/ Pt, Fe / Au, Fe / Ag and the like. The transition metal and the noble metal of these laminated film materials need not be particularly pure, and may be an alloy mainly composed of them. The thickness of the laminated film is arbitrary, but is usually 5 to 1000.
nm. Further, a laminate of three or more materials may be used as necessary.

In the present invention, the recording layer is preferably thin. This is because, when the recording layer is thick, heat transfer in the film thickness direction when the recording layer is heated is poor, and the recording layer may not be magnetized satisfactorily. Therefore, the thickness of the recording layer is preferably 200 nm or less. However, in order to maintain magnetization, the thickness of the recording layer is preferably 5 nm or more.

The magnetic layer as a recording layer maintains magnetization at room temperature and is demagnetized when heated, or magnetized when an external magnetic field is applied simultaneously with heating.

The coercive force of the magnetic layer at room temperature needs to maintain magnetization at room temperature and be uniformly magnetized by an appropriate external magnetic field. By setting the coercive force at room temperature of the magnetic layer to 2000 [Oe] or more, a medium that can maintain small magnetic domains and is suitable for high-density recording can be obtained. More preferably, it is 3000 [Oe] or more.

In the conventional magnetic transfer method, it was difficult to transfer to a medium having a very high coercive force. However, in the present invention, the magnetic layer is heated and the coercive force is sufficiently reduced to form a magnetic pattern. Application to a medium having a large magnetic force is preferable.

However, it is preferably 20 kOe or less. If it exceeds 20 kOe, a large external magnetic field is required for collective magnetization, and normal magnetic recording may be difficult.

The magnetic layer needs to be magnetized by a weak external magnetic field at an appropriate heating temperature while maintaining magnetization at room temperature. The larger the difference between the room temperature and the magnetization extinction temperature is, the more easily the magnetic domains of the magnetization pattern can be formed clearly. Therefore, the magnetization extinction temperature is preferably higher, more preferably 100 ° C. or higher, and more preferably 150 ° C. or higher. For example, there is a magnetization extinction temperature near the Curie temperature (slightly below the Curie temperature) or near the compensation temperature.

The Curie temperature is preferably 100 ° C. or higher. If the temperature is lower than 100 ° C., the stability of the magnetic domain at room temperature tends to be low. It is more preferably at least 150 ° C. The temperature is preferably 700 ° C. or lower. If the magnetic layer is heated to an excessively high temperature, the magnetic layer may be deformed.

When the magnetic recording medium is an in-plane magnetic recording medium, saturation recording is difficult with a conventional magnetic transfer method for a high-density magnetic recording medium having a high coercive force, and a magnetization pattern having a high magnetic field intensity is difficult. Generation becomes difficult, and the half-value width also increases. According to the present method, a good magnetization pattern can be formed even on an in-plane recording medium suitable for such a high recording density. In particular, when the saturation magnetization of the magnetic layer is 50 emu / cc or more, the effect of the demagnetizing field is large, so that the effect of applying the present invention is large.

The effect is higher when the value is 100 emu / cc or more. However, if it is too large, it is difficult to form a magnetized pattern. Therefore, it is preferably 500 emu / cc or less.

The magnetic recording medium is a perpendicular magnetic recording medium,
When the magnetization pattern is relatively large and the unit volume of one magnetic domain is large, the saturation magnetization becomes large, and the magnetization reversal is likely to occur due to the magnetic demagnetization, which causes noise and deteriorates the half width. However, in the present invention, good recording can be performed on these media by using a soft magnetic underlayer.

These recording layers may be provided in two or more layers in order to increase the recording capacity. At this time, it is preferable that another layer is interposed therebetween.

In the present invention, it is preferable to form a protective layer on the magnetic layer. That is, the outermost surface of the medium is covered with the hard protective layer. The protective layer functions to prevent the magnetic layer from being damaged by a head, a collision, or a mask between dust and dust. When a magnetic pattern forming method using a mask is applied as in the present invention, it also has a function of protecting the medium from contact with the mask.

The protective layer has an effect of preventing the heated magnetic layer from being oxidized. The magnetic layer is generally easily oxidized, and is more easily oxidized when heated. In the present invention, since the magnetic layer is locally heated by an energy beam or the like, it is desirable that a protective layer for preventing oxidation is formed in advance on the magnetic layer.

When there are a plurality of magnetic layers, a protective layer may be provided on the magnetic layer near the outermost surface. The protective layer may be provided directly on the magnetic layer, or may have another layer interposed therebetween as required.

A part of the energy rays is also absorbed by the protective layer, and serves to locally heat the magnetic layer by heat conduction. For this reason, if the protective layer is too thick, the magnetization pattern may be blurred due to heat conduction in the lateral direction. In order to reduce the distance between the magnetic layer and the head at the time of recording / reproducing, it is preferable that the thickness is smaller. Therefore, it is preferably 50 nm or less, more preferably 30 nm.
Or less, more preferably 20 nm or less. However,
In order to obtain sufficient durability, the thickness is preferably 0.1 nm or more, more preferably 1 nm or more.

The protective layer only needs to be hard and resistant to oxidation. Generally carbon, hydrogenated carbon,
A carbonaceous layer of nitrogenated carbon, amorphous carbon, SiC, or the like, SiO ₂ , Zr ₂ O ₃ , SiN, TiN, or the like is used. The protective layer may be a magnetic material.

Particularly, in order to make the distance between the head and the magnetic layer as close as possible, it is preferable to provide a very hard protective layer thinly. Therefore, a carbonaceous protective film is preferable in terms of impact resistance and lubricity, and diamond-like carbon is particularly preferable. Not only does it play a role in preventing the magnetic layer from being damaged by energy rays, it also becomes extremely resistant to damage to the magnetic layer by the head. The magnetic pattern forming method of the present invention can be applied to an opaque protective layer such as a carbonaceous protective layer.

Further, the protective layer may be composed of two or more layers. It is preferable to provide a layer containing Cr as a main component as a protective layer immediately above the magnetic layer because the effect of preventing oxygen from permeating the magnetic layer is high.

As described above, a lubricating layer is formed on the above-described layer structure. However, another layer may be added if necessary.

Various methods can be used for forming the underlayer, magnetic layer, and protective layer of the magnetic recording medium. For example, DC (magnetron) sputtering, high frequency (magnetron) sputtering, ECR sputtering, and vacuum deposition Physical vapor deposition method such as a method.

The conditions at the time of film formation include the ultimate vacuum, the substrate heating method and the substrate temperature,
The sputtering gas pressure, bias voltage and the like are determined as appropriate. For example, in the case of sputtering film formation, the ultimate degree of vacuum is usually 5 × 10 ⁻⁶ Torr or less, and the substrate temperature is from room temperature to room temperature.
400 ° C., sputtering gas pressure 1 × 10 ^{−3 to} 20 ×
10 ⁻³ Torr and a bias voltage of 0 to −500 V are preferable.

When the substrate is heated, it may be heated before the formation of the underlayer. Alternatively, when a transparent substrate having a low heat absorption is used, the substrate is heated after forming a seed layer mainly composed of Cr or an underlayer having a B2 crystal structure in order to increase the heat absorption. After that, a recording layer or the like may be formed.

When the magnetic layer is a rare earth magnetic layer,
From the viewpoint of corrosion and oxidation prevention, if the medium is disk-shaped, first mask the innermost and outermost parts of the disk,
A method of removing the mask at the time of forming the recording layer and then forming the protective layer, and completely covering the recording layer with the protective layer, or, in the case of two protective layers, covering the recording layer and the first protective layer. It is preferable that the mask is removed when forming the second protective layer while the recording layer is completely covered with the second protective layer, since corrosion and oxidation of the rare earth-based magnetic layer can be prevented. It is.

For the magnetic recording medium having each layer formed as described above, the entire magnetic layer is first uniformly magnetized,
A magnetization pattern is formed by application of an external magnetic field and local heating.

The surface roughness Ra of the medium after the formation of the magnetic pattern is preferably kept at 3 nm or less so as not to impair the running stability of the flying / contact type head. The medium surface roughness Ra is the roughness of the medium surface not including the lubricating layer, and is a stylus type surface roughness meter (model name: Tencor P-12 disk pro
Measurement length 400μm using a filer (manufactured by KLA Tencor)
Is a value calculated according to JIS B0601 after measurement. More preferably, the thickness is 1.5 nm or less.

Preferably, the surface waviness Wa of the medium after the formation of the magnetization pattern is kept at 5 nm or less. Wa is the waviness of the medium surface that does not contain a lubricating layer. Ra is measured using a stylus type surface roughness meter (model name: Tencor P-12 disk profiler (manufactured by KLA Tencor)) at a measurement length of 2 mm. This is a value calculated according to the calculation. More preferably, the thickness is 3 nm or less.

Prior to forming the magnetization pattern, first, a strong external magnetic field is applied to the magnetic recording medium to uniformly magnetize the entire magnetic layer in a desired magnetization direction. As a means for applying an external magnetic field, a magnetic head may be used, or a plurality of electromagnets or permanent magnets may be arranged so as to generate a magnetic field in a desired magnetization direction. Further, these different means may be used in combination.

In the case of a medium having an easy axis of magnetization in the in-plane direction, the desired magnetization direction is the same as or opposite to the running direction of the data write / reproduce head (the relative movement direction of the medium and the head). When the axis of easy magnetization is perpendicular to the in-plane direction, the direction is either the vertical direction (upward or downward). Therefore, an external magnetic field is applied so as to be magnetized in such a manner.

To magnetize the entire magnetic layer uniformly in a desired direction means to magnetize the entire magnetic layer in substantially the same direction. However, not exactly all of the magnetic layer but at least a region where a magnetization pattern is to be formed is formed. It suffices if they are magnetized in the same direction.

The strength of the magnetic field depends on the characteristics of the magnetic layer of the magnetic recording medium, and it is preferable that the magnetic layer is magnetized by a magnetic field that is at least twice the coercive force of the magnetic layer at room temperature. If it is lower than this, the magnetization may be insufficient. However, usually, the coercive force of the magnetic layer at room temperature is about 5 times or less due to the capability of the magnetizing device used for applying the magnetic field.

When the medium has a disk shape, the direction of application of the external magnetic field is preferably one of a circumferential direction, a radial direction, and a direction perpendicular to the plate surface.

When applying an external magnetic field simultaneously with heating,
By applying an external magnetic field over the heated large area, a plurality of magnetization patterns can be formed at once.

As means for applying an external magnetic field to the magnetic layer, a magnetic head may be used, or a plurality of electromagnets or permanent magnets may be arranged and used so as to generate a magnetic field in a desired magnetization direction. May be used in combination. In order to efficiently magnetize a high coercivity medium suitable for high-density recording, a permanent magnet such as a ferrite magnet, a neodymium-based rare-earth magnet, and a samarium-cobalt-based rare-earth magnet is suitable.

After uniformly magnetizing the entire magnetic layer in this way, a magnetization pattern is formed by local heating and application of an external magnetic field.

As the local heating and the application of an external magnetic field for forming the magnetization pattern, preferably, an external magnetic field is applied to uniformly magnetize the magnetic thin film in a desired direction in advance, and then the magnetic thin film is locally heated. An external magnetic field is applied to magnetize the heating section in a direction opposite to the desired direction to form a magnetized pattern. According to this, since the magnetic domains in opposite directions are clearly formed, a magnetization pattern having a high signal intensity and a good C / N and S / N can be obtained.

The heating for local heating may be performed at a temperature at which the coercive force of the magnetic layer is reduced. Preferably, it is heated to 100 ° C or higher. Magnetic layers that are affected by an external magnetic field below 100 ° C. tend to have low domain stability at room temperature. Further, the heating temperature is preferably 700 ° C. or lower. If the heating temperature is too high, the magnetic layer may be deformed.

The direction of the magnetic field applied simultaneously with the heating is generally opposite to the direction of the uniform magnetization. The stronger the magnetic field, the more easily the magnetic pattern is formed. Preferably, the magnetic field is at least １ ／ of the coercive force of the magnetic layer at room temperature. If it is lower than this, the heating unit may be magnetized again in the same direction as the surroundings under the influence of the magnetic field from the surrounding magnetic domains during cooling.

However, 2/3 of the coercive force of the magnetic layer at room temperature
It is preferably at most, and more preferably at most 1/2 times. If it is larger than this, the magnetic domains around the heating section may be affected.

The heating means for locally heating the magnetic layer only needs to have a function capable of partially heating the surface of the magnetic layer. However, in consideration of prevention of heat diffusion to unnecessary parts and controllability, It is preferable to use power control and an energy ray such as a laser which can easily control the size of a portion to be heated.

At this time, it is preferable to use a mask together. By irradiating the energy beam through the mask, a plurality of magnetization patterns can be formed at a time, so that the magnetization pattern formation process is short and simple.

Further, it is preferable to control the heating portion and the heating temperature by making the energy beam more pulse-shaped than continuous irradiation.

It is particularly preferable to use a pulse laser light source. A pulsed laser light source oscillates a laser intermittently in a pulsed manner. Compared to a continuous laser which is intermittently pulsed by an optical component such as an acousto-optic device (AO) or an electro-optic device (EO), it is pulsed. It is very preferable that a laser having a high power peak value can be irradiated in a very short time and heat is hardly accumulated.

When a continuous laser is pulsed by an optical component, the pulse has substantially the same power over the pulse width. On the other hand, a pulsed laser light source accumulates energy by resonance in the light source, for example, and emits a laser as a pulse at a time. In the present invention,
In order to form a high-contrast and high-accuracy magnetization pattern, it is preferable to rapidly heat and then rapidly cool in a very short time. Therefore, use of a pulsed laser light source is suitable.

The medium surface on which the magnetization pattern is formed preferably has a large temperature difference between when the pulsed energy beam is irradiated and when it is not irradiated, in order to increase the pattern contrast or the recording density. Therefore, it is preferable that the temperature be lower than room temperature when the pulsed energy beam is not irradiated. Room temperature is about 25 ° C.

When using pulsed energy rays, the external magnetic field may be applied continuously or in a pulsed manner.

It is preferable that the energy ray has a wavelength of 1100 nm or less. If the wavelength is shorter than this, the diffraction effect is small and the resolution is increased, so that a fine magnetization pattern is easily formed. More preferably, the wavelength is 600 nm or less. In addition to the high resolution, the diffraction is small, so that the spacing between the mask and the magnetic recording medium by the gap can be widened, handling is easy, and there is an advantage that the magnetization pattern forming apparatus can be easily configured. The wavelength is 1
It is preferably at least 50 nm. If it is less than 150 nm, the absorption of the synthetic quartz used for the mask becomes large, and the heating tends to be insufficient. If the wavelength is 350 nm or more, optical glass can be used as a mask.

Specifically, an excimer laser (157,
193, 248, 308, 351 nm), the second harmonic (532n) of the YAG Q-switched laser (1064 nm)
m) 3rd harmonic (355 nm) or 4th harmonic (266n)
m), an Ar laser (488 nm, 514 nm), a ruby laser (694 nm) and the like.

The power of the energy beam may be selected at an optimum value according to the magnitude of the external magnetic field. The power per pulse of the pulsed energy beam is 1000 mJ / cm ^2.
It is preferable to set the following. If a power larger than this is applied, the surface of the magnetic recording medium may be damaged and deformed by the pulsed energy rays. If the roughness Ra increases to 3 nm or more and the undulation Wa increases to 5 nm or more due to deformation, there is a possibility that the traveling of the floating / contact type head may be hindered.

It is more preferably at most 500 mJ / cm ² , further preferably at most 200 mJ / cm ² .
In this region, a magnetization pattern with high resolution is easily formed even when a substrate having relatively large thermal diffusion is used. Further, the power is preferably set to 10 mJ / cm ² or more. If it is smaller than this, the temperature of the magnetic layer hardly rises and magnetic transfer hardly occurs. The required power tends to increase as the pattern width decreases. Further, the shorter the wavelength of the energy ray, the lower the upper limit of the power that can be applied.

When the substrate used in the present invention is a metal or alloy such as Al or the like, since the thermal conductivity is high, the locally applied heat spreads to a portion other than a desired portion, which may distort the magnetization pattern. The power is preferably in the range of 30 to ²⁰⁰ mJ / cm ² so as not to cause any physical damage to the substrate due to excessive energy.

When the substrate is made of ceramics such as glass, the power is 1 because the heat conduction is low and the heat accumulation at the pulsed energy beam irradiation site is large as compared with Al or the like.
It is preferably in the range of 0 to 200 mJ / cm ² .

When the substrate is made of a resin such as polycarbonate, the power is 1 because the heat accumulation at the pulsed energy beam irradiation site is large and the melting point is lower than that of glass or the like.
It is preferably in the range of 0 to 180 mJ / cm ² .

If the magnetic layer, the protective layer, and the lubricating layer may be damaged by the energy beam, the power of the pulse energy beam is reduced to increase the intensity of the magnetic field applied simultaneously with the pulse energy beam. Such means can also be taken. For example, a magnetic field as large as possible of 25 to 75% of the coercive force of the magnetic recording medium at room temperature is applied to lower the irradiation energy.

The pulse width of the pulse energy beam is 1 μm.
sec or less is desirable. If the pulse width is wider than this, the heat generated by the energy given to the magnetic recording medium by the pulsed energy beam is dispersed, and the resolution tends to be reduced. When the power per pulse is the same, a shorter pulse width and irradiation with strong energy at one time tend to reduce thermal diffusion and increase the resolution of the magnetization pattern. More preferably, it is 100 nsec or less. In this region, a magnetization pattern with high resolution is easily formed even when a substrate such as Al having a relatively large thermal diffusion of a metal is used. When forming a pattern having a minimum width of 2 μm or less,
The pulse width is preferably set to 25 nsec or less. That is, if importance is placed on the resolution, the shorter the pulse width, the better. Also, the pulse width is preferably 1 nsec or more. This is because it is preferable to maintain the heating until the magnetization reversal of the magnetic layer is completed. In the present application, the minimum width of the pattern refers to the narrowest length in the pattern. In the case of a square pattern, the short side is used. In the case of a circular pattern, the short side is used.

As one type of pulsed laser, there is a laser such as a mode-locked laser capable of generating picosecond and femtosecond level ultrashort pulses at a high frequency. During the period of irradiating the ultrashort pulse at a high frequency, the laser is not irradiated for a very short time between each ultrashort pulse, but the heating part is hardly cooled because it is a very short time. That is, the region once heated to the Curie temperature or higher is maintained at the Curie temperature or higher.

Therefore, in such a case, the continuous irradiation period (the continuous irradiation period including the time during which the laser is not irradiated between the ultrashort pulses) is defined as one pulse. In addition, the integral value of the irradiation energy amount during the continuous irradiation period is expressed by the power per pulse (mJ).
/ Cm ² ).

An energy beam such as a laser generally has an intensity distribution (energy density distribution) in a beam spot, and a difference in temperature rise due to the energy density also occurs when the energy beam is irradiated and locally heated. For this reason, a difference in transfer strength occurs locally due to uneven heating.

Therefore, for example, an energy ray source having a small intensity distribution is used, only a portion having a small intensity distribution of the energy ray is transmitted through a light shielding plate or the like, and then enlarged as necessary, or a homogenizer or a condenser lens is used. For example, the intensity distribution in the beam spot of the energy ray is suppressed to be small.

Preferably, the energy beam is subjected to an intensity distribution uniforming process in advance. The distribution of the heating state in the irradiated area can be suppressed small, and the distribution of the magnetic intensity of the magnetization pattern can be suppressed small. Therefore, when reading the signal intensity using the magnetic head, it is possible to form a magnetization pattern with high signal intensity uniformity.

As the process of equalizing the intensity distribution, for example, the following process can be mentioned. For example, a homogenizer or a condenser lens may be used to make the energy uniform, or a light shielding plate or a slit may be used to transmit only a portion of the energy beam having a small intensity distribution, and may be enlarged as necessary.

Preferably, when the energy rays are once optically divided and then superimposed by superimposing them, the energy rays can be used without waste and the use efficiency is good.
In the present invention, for heating the magnetic layer, it is preferable to irradiate a high-intensity energy ray in a short time, and for this purpose, it is preferable to use energy without waste.

For example, an energy ray having an elliptical beam shape has a short axis direction distribution and a long axis direction distribution. At this time, by dividing the length of the beam in the short axis direction into, for example, three by a prism array (multi-cylindrical lens) or the like and then superposing the beams, the difference in intensity can be dispersed, and the intensity distribution in the short axis direction can be made uniform to some extent. Similarly, by dividing the length of the beam in the major axis direction into, for example, seven by a prism array (multi-cylindrical lens) or the like and then superimposing the beams, the intensity distribution in the major axis direction can be made uniform to some extent. If both are performed together, a beam with a small intensity distribution with increased uniformity as a whole can be obtained. However, it may be performed only in one axial direction as needed. When the intensity distribution is large, uniformity can be increased by increasing the number of divisions.

By passing two or more prism arrays in the same axial direction, the same effect as increasing the number of divisions can be obtained. Alternatively, the biaxial direction may be divided at a time using a fly-eye lens having a large number of lenses formed in the biaxial direction.

Alternatively, the intensity distribution can be easily made uniform by passing the energy ray through an aspheric lens such as a cylindrical lens. In particular, when the energy beam is a beam having a small diameter, it is often possible to sufficiently homogenize even by this method, and the optical system can be simplified, which is preferable. In addition, a small diameter means about 0.05-1 mm in diameter.

If the above processing alone is not enough to achieve uniformity, a light shielding plate may be used in combination to cut or narrow the peripheral portion of the beam for further uniformity.

In the present invention, it is preferable to irradiate an energy ray through a mask to locally heat the film. Once a mask is formed, a magnetized pattern of any shape can be formed on a medium, so that a complicated pattern or a special pattern that has been difficult to make by a conventional method can be easily formed.

For example, in the phase servo method of a magnetic disk, a magnetization pattern that extends linearly obliquely with respect to a radius and a track from the inner circumference to the outer circumference is used. Such a pattern that is continuous in the radial direction or a pattern that is oblique to the radius is difficult to produce by a conventional servo pattern forming method of recording a servo signal one track at a time while rotating the disk. According to the present invention, such a magnetization pattern can be formed simply and in a short time by a single irradiation, without requiring a complicated calculation or a complicated device configuration.

Even if the mask does not cover the entire surface of the magnetic disk, the mask may have a size including a repetition unit of the magnetization pattern, and can be used while being moved, so that the mask can be formed simply and inexpensively.

The mask may be any mask as long as the intensity distribution of the energy rays is changed corresponding to the magnetization pattern to be formed, and the density (intensity distribution) of the energy rays is formed on the surface of the magnetic disk. For example, a photomask having a transmission portion that transmits an energy ray according to a pattern, or a hologram mask on which a hologram that forms a specific pattern on a medium is recorded. Thereby, a plurality of or large-area magnetized patterns can be formed at a time, so that the magnetized pattern forming step is short and simple. According to the hologram mask, it is easy to form a sharp and clear pattern even if the distance between the mask and the medium is sufficiently long, which is preferable.
Photomasks are preferred in that they can be made easily and inexpensively.

Although the material of the mask is not limited, if the mask is made of a non-magnetic material in the present invention, a magnetized pattern can be formed with uniform clarity in any pattern shape, and a uniform and strong reproduced signal can be obtained. .

When using a mask containing a ferromagnetic material,
It is not preferable because the magnetic field distribution is disturbed by the magnetization. Due to the ferromagnetic property, in the case of a pattern shape obliquely inclined from the radial direction of the magnetic disk or an arc-shaped pattern extending in the radial direction, it is difficult to obtain a good signal because the magnetic domains do not sufficiently oppose each other at the magnetization transition portion.

The mask is disposed between the light source for energy rays and the magnetic layer (magnetic recording medium). If importance is placed on the accuracy of the magnetization pattern, it is preferable that all or part of the mask be in contact with the medium. The effect of laser beam diffraction can be minimized, and a magnetization pattern with high resolution can be formed.

However, in order to reduce defects and scratches,
It is preferable to provide a gap between the mask and the medium at least in a region where the magnetization pattern of the medium is formed. It is possible to suppress the damage of the medium and the mask and the occurrence of defects due to the insertion of dust and the like.

In the case where the lubricating layer is provided before the formation of the magnetic pattern, it is particularly preferable to provide a gap between the mask and the medium in order to minimize the adhesion of the lubricant to the mask. .

As a method of maintaining the gap between the magnetic pattern forming region of the magnetic recording medium and the mask, any method can be used as long as both can be maintained at a fixed distance. For example, the mask and the medium may be held by a specific device to keep a certain distance. Further, a spacer may be inserted between the two at a place other than the magnetization pattern forming region. A spacer may be integrally formed with the mask itself.

If a spacer is provided between the mask and the magnetic recording medium on the outer peripheral portion and / or the inner peripheral portion of the magnetic pattern forming region of the medium, an effect of correcting the undulation on the surface of the magnetic recording medium is produced. It is good because the accuracy increases.

Referring to FIG. 1, a method of forming a magnetic pattern using a photomask will be described.

First, the magnetic disk 101 is uniformly magnetized in advance in one circumferential direction by an external magnetic field. After that, the magnetic disk 101 is mounted on the spindle 120. That is, it is arranged on the turntable 121, the photomask 102 is attached via the spacer 122, and the holding plate 1
23, and fix it with a set screw (not shown). That is, a space S is provided between the magnetic disk 101 and the photomask 102. Here, a pulsed laser beam 103 is irradiated. At the same time, an external magnetic field 104 is applied. This external magnetic field is in the opposite direction to the external magnetic field that was previously magnetized uniformly.

FIG. 2 shows an optical system for laser irradiation. After the laser oscillated from the laser light source passes through the programmable shutter, it is irradiated on the magnetized disk via an attenuator, a collimator lens that expands the beam diameter to make parallel light, a homogenizer that makes the beam intensity uniform, and a mask.

A mask having a plurality of transmission portions formed according to the magnetization pattern to be formed is prepared, and the magnetic layer is irradiated with a laser beam through the mask. If the beam diameter is set to a large diameter or a horizontally elongated elliptical shape, etc., and the magnetization pattern for multiple tracks or multiple sectors is collectively irradiated, the recording efficiency will increase further and the servo recording time will increase with the increase in the capacity from now on The problem of doing so is also improved and is very preferable.

The photomask may be a mask having a transmission part and a non-transmission part corresponding to a desired magnetization pattern. A metal such as Cr is formed on a transparent master such as quartz glass or soda lime glass by sputtering. Then, a desired transmitting portion and a non-transmitting portion can be formed by applying a photoresist thereon and performing etching or the like. In this case, a portion having a Cr layer on the master is an energy ray non-transmissive portion, and a portion of only the master is a transmissive portion.

The mask thus formed usually has irregularities, and the projections are impermeable to energy rays, and the projections are brought close to or almost in contact with the medium. Alternatively,
After forming such a mask, a material that is transparent to energy rays may be buried in the concave portions to make the surface almost in contact with the medium flat.

The spacer is preferably made of a hard material. Further, since an external magnetic field is used for pattern formation, it is preferable that the magnet is not magnetized. Preferably, a metal such as stainless steel or copper, or a resin such as polyimide is used. The height is arbitrary, but is usually several μm to several hundred μm.

When external magnetization is applied simultaneously with heating,
It is preferable that an external magnetic field can be simultaneously applied to a plurality of transmission portions of the mask.

The minimum gap between the mask and the magnetic recording medium is 0.1
It is preferable that the thickness is at least μm, whereby damage and defects of the magnetic recording medium and the mask due to pinching of dust and the like can be suppressed. That is, by setting the interval to 0.1 μm or more, it is possible to prevent the magnetic pattern forming portion from unexpectedly contacting the mask due to the undulation of the medium surface. Therefore, since the thermal conductivity of the medium changes at the contact portion, the susceptibility to magnetization is specifically changed accordingly, and there is no problem that a magnetized pattern is not formed as a desired pattern. More preferably, the thickness is 0.2 μm or more. However, the interval is preferably 1 mm or less. Thereby, there is no problem that the diffraction of the energy beam is small and the magnetization pattern is blurred.

For example, an excimer laser (248 nm)
When a 2 × 2 μm pattern (a pattern having 2 μm transmissive portions and 2 μm non-transmissive portions alternately formed) formed on a photomask is transferred to a medium, the distance between the mask and the medium is about 25 to 45 μm. It must be kept below. If the distance is longer than this, the pattern of the light and dark of the laser light is not clear due to the diffraction phenomenon. In the case of a 1 × 1 μm pattern (a pattern having 1 μm transmitting portions and 1 μm non-transmitting portions alternately), the distance is set to about 10 to 15 μm or less.

When a photomask is used, it is preferable to keep the distance from the medium as short as possible within the range of the above conditions. This is because the longer the distance, the more easily the magnetic pattern is blurred due to the wraparound of the irradiated energy beam. In order to improve this and obtain a clearer pattern, by forming a thin transmission part that functions as a diffraction grating outside the transmission part of the mask, or by providing a means that functions as a half-wave plate The wraparound light can be canceled by interference.

On the other hand, when using a hologram mask,
Since the distance of the pattern corresponding to the holography to the image plane is determined in advance, the distance from the medium is adjusted to the distance. Note that by using a prism, the mask and the medium can be brought close to each other.

A magnetic disk may have a magnetic layer formed on both main surfaces of the disk. In such a case, the formation of the magnetic pattern of the present invention may be performed on one side at a time, or may be performed sequentially. Means for applying an external magnetic field may be provided on both sides of the magnetic disk to simultaneously form a magnetization pattern on both sides.

When two or more magnetic layers are formed on one surface, and it is desired to form different patterns for each layer, the energy rays to be irradiated are focused on each layer, so that each layer is individually heated, and the individual pattern is formed. Can be formed.

When forming a magnetized pattern, a light shielding plate capable of partially shielding energy rays is provided between a light source of the energy rays and the mask or a region where irradiation between the mask and the medium is not desired. Is preferably provided to prevent energy beam re-irradiation.

The light-shielding plate may be any plate that does not transmit the wavelength of the energy beam to be used, and may reflect or absorb the energy beam. However, when the energy beam is absorbed, it is heated and easily affects the magnetization pattern. Therefore, a material having good thermal conductivity and high reflectance is preferable. For example, C
It is a metal plate of r, Al, Fe or the like.

It is also preferable to use a reduction imaging technique for the optical system. Patterned energy rays having an intensity distribution corresponding to the magnetization pattern to be formed are reduced and imaged on the medium surface. According to this, the accuracy of the magnetization pattern is not limited by the mask patterning accuracy and the alignment accuracy as compared with the case of passing through the mask after the energy beam is narrowed down by the objective lens, that is, in the case of the proximity exposure. A fine magnetized pattern can be formed with high accuracy. Further, since the mask and the medium are separated from each other, it is hardly affected by dust on the medium. Hereinafter, the present technology may be referred to as a reduced imaging technology (imaging optical system).

The energy distribution emitted from the light source changes its intensity distribution through a mask and is reduced and imaged on the medium surface through imaging means such as an imaging lens. The imaging lens may be referred to as a projection lens, and the reduced imaging may be referred to as reduced projection.

In the present technology, an image forming means is provided between the mask and the medium. Conventionally, when a photomask and a medium are brought into close contact with each other and irradiated with energy rays, depending on the material, the mask absorbs the energy rays and is heated, and the temperature of the surface of the adhered medium also increases, so that the magnetization pattern may not be clearly written. However, according to the present technology, this problem is also solved.

That is, it is preferable that the medium surface on which the magnetization pattern is formed has a large temperature difference between the time of irradiation of the pulsed energy beam and the time of non-irradiation in order to increase the pattern contrast or the recording density. Therefore, the medium surface is preferably at room temperature or lower when no pulsed energy beam is irradiated. Room temperature is about 25 ° C.

It is preferable to pass a condenser lens before the mask because the intensity distribution of the energy rays can be made uniform and the energy rays can be efficiently collected on the imaging lens.

The reduction imaging technique can be applied to any size or shape of the magnetization pattern as long as the beam diameter of the energy ray and the intensity of the external magnetic field allow. The smaller the magnetization pattern, the higher the effect. When the minimum width of the magnetization pattern is 2 μm or less, alignment between the medium and the mask becomes particularly difficult, so that the application effect of the present technology is high. More preferably 1
μm or less. There is no lower limit on the pattern that can be formed, and a fine pattern up to the wavelength limit of energy rays can be theoretically formed. For example, it is about 100 nm by an excimer laser or the like.

After forming the magnetization pattern in this way, the lubricating layer is subjected to uniform processing. The specific method of the homogenization process is as described above.

Next, a magnetic recording apparatus provided with the magnetic recording medium manufactured as described above will be described.

This magnetic recording apparatus includes a magnetic recording medium with a magnetization pattern manufactured by the above-described method, a driving unit for driving the magnetic recording medium in a recording direction, a magnetic head including a recording unit and a reproducing unit, and a magnetic head. It has means for moving relative to the magnetic recording medium, and means for recording / reproducing signal processing for inputting recording signals to the magnetic head and outputting reproduction signals from the magnetic head. As a magnetic head, a flying / contact magnetic head is usually used to perform high-density recording.

By using a magnetic recording medium on which a magnetic pattern such as a fine and high-precision servo pattern is formed by the method of the present invention, the magnetic recording apparatus can perform high-density recording. Further, since the medium has no scratches and few defects, recording with few errors can be performed.

Further, after assembling the magnetic recording medium into the apparatus, the magnetic pattern is reproduced by a magnetic head to obtain a signal, and a servo burst signal is recorded by the magnetic head on the basis of the signal. By using
A precise servo signal can be easily obtained.

Even after recording the servo burst signal with the magnetic head, if a signal recorded as a magnetization pattern according to the present invention remains in an area not used as a user data area, the magnetic head may be displaced due to some disturbance. It is easy to return to the desired position even when the magnetic recording device has a signal by both writing methods,
High reliability.

A description will be given of a typical magnetic disk device as a magnetic recording device.

The magnetic disk device generally includes a shaft for fixing one or more magnetic disks in a skewered manner,
A motor for rotating a magnetic disk joined to the shaft via a bearing, a magnetic head used for recording and / or reproduction, an arm to which the head is attached, and a head on the magnetic recording medium via the head arm It comprises an actuator that can be moved to an arbitrary position, and the recording / reproducing head moves over the magnetic recording medium at a constant flying height. The recording information is converted into a recording signal via a signal processing means and recorded by a magnetic head. Also,
The reproduction signal read by the magnetic head is inversely converted through the signal processing means to obtain reproduction information.

On the disc, information signals are recorded in sector units along concentric tracks. Servo patterns are usually recorded between sectors. The magnetic head reads a servo signal from the pattern, thereby accurately performing tracking at the center of the track, and reads an information signal of the sector. Tracking is also performed during recording.

As described above, a servo pattern for generating a servo signal is required to have a particularly high precision due to the property of being used for tracking when recording information. In addition, since the servo pattern which is often used at present is composed of two sets of patterns which are shifted from each other by ピ ッ チ pitch, it is necessary to form the servo pattern at every ピ ッ チ pitch of the information signal, and the accuracy is twice as high. Is required.

However, in the conventional servo pattern forming method, the write track width is 0.2 to 0.2 due to the influence of vibration caused by the difference in the center of gravity between the external pin and the actuator.
The limit is about 0.3 μm, and the accuracy of the servo pattern cannot keep up with the increase in the track density, which is preventing the improvement of the recording density and the cost reduction of the magnetic recording apparatus.

According to the present invention, a highly accurate magnetization pattern can be efficiently formed, so that a servo pattern can be formed with high accuracy in a much shorter time and in a shorter time than conventional servo pattern formation methods. The track density of the medium can be increased to 40 kTPI or more. Therefore, a magnetic recording device using this medium can perform high-density recording.

Further, when the phase servo method is used, a continuously changing servo signal can be obtained, so that the track density can be further increased, and tracking with a width of 0.1 μm or less can be performed, so that higher density recording is possible. is there.

As described above, in the phase servo method, for example, a magnetization pattern that extends linearly obliquely with respect to the radius from the inner periphery to the outer periphery is used. Such a continuous pattern or a diagonal pattern in the radial direction is difficult to produce by a conventional servo pattern forming method of recording a servo signal one track at a time while rotating a disk, and requires a complicated calculation and configuration.

However, according to the present invention, once a mask corresponding to the shape is once formed, the pattern can be easily formed only by irradiating an energy beam through the mask.
A medium used for the phase servo method can be simply, quickly, and inexpensively created. As a result, it is possible to provide a phase servo type magnetic recording device capable of high-density recording.

In the conventional mainstream servo pattern forming method, a dedicated servo writer is used in a clean room after a medium is incorporated in a magnetic recording device (drive).

Each drive is mounted on a servo writer, and the pins of the servo writer are inserted into holes on either the front or rear surface of the drive, and recording is performed one pattern at a time along the track while mechanically moving the magnetic head.
Therefore, it takes a very long time of about 15 to 20 minutes per drive. These operations had to be performed in a clean room because a dedicated servo writer was used and a hole was formed in the drive, which was complicated in the process and increased the cost.

According to the present invention, a servo pattern or a reference pattern for recording a servo pattern can be collectively recorded by irradiating an energy beam through a mask in which a pattern has been recorded in advance, and the servo pattern can be recorded on a medium in a very simple and short time. A pattern can be formed. A magnetic recording apparatus incorporating a medium on which a servo pattern is formed in this way eliminates the need for the servo pattern writing step.

Alternatively, in a magnetic recording apparatus incorporating a medium on which a servo pattern recording reference pattern is formed, a desired servo pattern can be written in the apparatus based on the reference pattern, and the servo writer is not required. And
There is no need to work in a clean room.

Further, it is not necessary to make a hole on the back side of the magnetic recording apparatus, which is preferable in terms of durability and safety.

Further, according to the present invention, since the mask and the medium do not need to be in close contact with each other, damage due to contact between the magnetic recording medium and other constituent members and damage to the medium due to pinching of minute dust or dust can be prevented. And prevent the occurrence of defects.

As described above, according to the present invention, a magnetic recording apparatus capable of high-density recording can be obtained by simple steps at low cost.

As the magnetic head, various types such as a thin film head, an MR head, a GMR head, and a TMR head can be used. By configuring the reproducing section of the magnetic head with the MR head, sufficient signal intensity can be obtained even at a high recording density, and a magnetic recording apparatus with a higher recording density can be realized.

Further, the magnetic head was set at a flying height of 0.001 μm.
When flying at a low height of not less than m and less than 0.05 μm, the output is improved and a high device S / N is obtained, and a large-capacity and high-reliability magnetic recording device can be provided.

The recording density can be further improved by combining a signal processing circuit based on the maximum likelihood decoding method. For example, the track density is 13 kTPI or more, and the linear recording density is 250 kFCI.
As described above, a sufficient S / N can be obtained even when recording / reproducing at a recording density of 3 Gbits / inch 2 or more.

Further, the reproducing portion of the magnetic head is provided between a plurality of conductive magnetic layers which generate a large resistance change due to a relative change in their magnetization directions due to an external magnetic field, and the conductive magnetic layers. G consisting of a conductive non-magnetic layer
MR head or G using spin valve effect
By using the MR head, the signal strength can be further increased, and 10 Gbits or more per square inch
A highly reliable magnetic recording device having a linear recording density of 50 kFCI or more can be realized.

[0211]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to the embodiments unless it exceeds the scope of the gist.

(Example 1) A 3.5 inch diameter NiP-plated aluminum alloy substrate was washed and dried, and the ultimate vacuum was 1 × 10 ⁻⁷ Torr and the substrate temperature was 350.
° C, bias voltage: -200 V, sputtering gas:
Ar, gas pressure: 3 × 10 ⁻³ Torr, Cr
₉₀ Mo ₁₀ was formed to a thickness of 18 nm, Cr ₆₃ Co ₃₇ was formed to a thickness of 2 nm, CoCrPtB was formed to a thickness of 15 nm as a recording layer, and carbon (diamond-like carbon) was formed to a thickness of 5 nm as a protective layer. A magnetic disk for in-plane recording having a coercive force of 3200 Oe at room temperature was obtained.

A 1.5-nm thick fluorine-based lubricant was applied thereon as a lubricating layer, and baked at 100 ° C. for 40 minutes. Specifically, DOL4000 (average molecular weight 400
0, manufactured by Audimont Co., Ltd.) and dissolved in PF5052 (manufactured by 3M), which is a fluorine-based solvent, to a concentration of 0.3 g / L, and the magnetic disk was immersed. Then 100
By heating in a clean oven at 40 ° C. for 40 minutes, low molecular weight volatile components were removed and at the same time the adhesion to the protective layer was increased.

After the temperature was lowered to room temperature, a glide inspection was performed using a calibrated glide head and a glide inspection machine. In the region from a radius of 46 mm to 23 mm, the value of 0.
The glide test of 6 μinch passed.

In order to form a magnetic pattern on the disks, each disk was mounted on a spindle, and a magnet having a saturation magnetic flux density of 10 kGauss (10 kOe) was moved from the outside to the inside of the disk while rotating at 5 rpm to change the disk surface. It was uniformly (uniformly) magnetized.

While applying a magnetic field of 1.5 kGauss (1.5 kOe) to the above medium in a direction opposite to the direction applied in the previous step, an excimer laser having a wavelength of 248 nm was irradiated by a spacer at a distance of 10 μm from the medium by a spacer. 130mJ / cm ²
The entire surface of the medium was irradiated once with an energy density of? The mask is a mask in which chromium and chromium oxide are formed as a non-transmissive part on quartz glass to form a pattern having a line and space width of 1 μm. In this way, the magnetization was inverted only in the region heated by the laser irradiation to form a magnetization pattern.

Next, the lubricating layer after the formation of the magnetization pattern was subjected to a uniforming treatment. That is, the disc was placed in a 150 ° C. clean oven and subjected to a heat treatment for a homogenization treatment for 5 minutes. This temperature was measured with a radiation thermometer.

The magnetic recording medium thus manufactured was mounted on a spin stand and rotated at 4500 rpm, and then FH (flying height, flying height) 0.9 μinch
The head was sought 20 times from the outer circumference of 46 mm to the inner circumference of 22 mm while maintaining the height of the head. After the head was sought 20 times, dirt on the head was observed at a magnification of 160 times using a differential interference microscope, and the dirt on the head was evaluated.

Further, the above-mentioned medium was manufactured by Hitachi Electronics RQ3000.
When the glide test was performed with a glide tester, it was 0.5μ.
passed to inch.

A disk having the same configuration as in Example 1 (before forming the magnetic pattern) was beam-shaped to 10 mm × 3.
The same location was irradiated 10 times with a 0 mm excimer laser (λ = 248 nm).

After that, when the irradiated portion and the non-irradiated portion were measured with a film thickness measuring device OSA-5100 (Candela), the irradiated portion had only 90% of the film thickness of the non-irradiated portion.

Thus, it can be seen that the film thickness is reduced only in the heated portion due to local heating during the formation of the magnetization pattern, and the film thickness is not uniform.

A disk having the same configuration as in Example 1 (before forming the magnetic pattern) was beam-shaped to 10 mm × 3.
170 mm excimer laser (wavelength 248 nm)
Irradiation was performed once at an energy density of mJ / cm ^{2, and} the peak intensity of the low molecular weight hydrocarbon component was measured by TOF-SIMS. Further, after this, 150
The same measurement was performed by performing a heat treatment at 5 ° C. × 5 minutes. Then, the peak heights were compared. That is, the low molecular weight hydrocarbon components after the local heating as in the formation of the magnetization pattern and after the heat treatment for further uniformity were compared. The results are as shown in Table 1 below, and it was confirmed that low molecular weight components were reduced by heating in an oven.

[0224]

[Table 1]

Example 2 A disk was manufactured and a magnetization pattern was formed in the same manner as in Example 1.

Next, the lubricating layer was subjected to a uniformizing treatment. That is, the entire surface of the medium was irradiated once with an excimer laser at an energy density of 70 mJ / cm ² . Disk surface temperature is 1
It was about 20 ° C.

The above medium was evaluated in the same manner as in Example 1. 2
The stain on the head after 0 times of seek was evaluated, but no deposit was found. The glide test passed 0.5 μinch.

Comparative Example 1 A disk was manufactured and a magnetic pattern was formed in the same manner as in Example 1.

The above medium was used in Example 1 without performing the homogenizing process.
Was evaluated in the same way as The dirt on the head after 20 seeks was evaluated. Observation with a differential interference microscope revealed that organic matter on the oil droplets adhered to the pad portion of the head. Oil drop part is S
Observation using EM-EDX revealed that it was a lubricant because it mainly contained carbon and oxygen components. In the glide test, the number of hits surged from 0.8 μinch.

[0230]

As described above, according to the present invention, it is possible to eliminate the uneven distribution of the lubricant and the low molecular weight component in the portion heated during the formation of the magnetization pattern. This makes it possible to prevent the magnetic head from being stained. Also, immediately after the formation of the magnetization pattern, the medium can be incorporated into the drive, and inspection and evaluation can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magnetization pattern forming apparatus.

FIG. 2 is a block diagram of an optical system for laser irradiation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Magnetic disk 102 Mask 103 Laser 104 External magnetic field

Claims (8)

[Claims] 1. A method of manufacturing a magnetic recording medium with a magnetic pattern, comprising: forming at least a magnetic layer and a lubricating layer on a substrate; and forming a magnetic pattern on the magnetic layer by an external magnetic field applying step and a local heating step. A method for manufacturing a magnetic recording medium, comprising: after forming a magnetization pattern, performing a homogenization process for uniformizing properties of the lubricating layer. 2. A method for manufacturing a magnetic recording medium with a magnetic pattern, comprising: forming at least a magnetic layer and a lubricating layer on a substrate; and forming a magnetic pattern on the magnetic layer by an external magnetic field applying step and a local heating step. A method for manufacturing a magnetic recording medium, comprising: performing heat treatment on the entire surface of the lubricating layer after forming a magnetization pattern. 3. The method of manufacturing a magnetic recording medium according to claim 2, wherein the entire surface heat treatment is laser irradiation. 4. The method for manufacturing a magnetic recording medium according to claim 1, wherein the coercive force of the medium is 3000 Oe or more. 5. The method for manufacturing a magnetic recording medium according to claim 1, wherein the local heating step for forming the magnetization pattern is performed by irradiating an energy beam. . 6. The method for manufacturing a magnetic recording medium according to claim 4, wherein the irradiation of the energy beam is performed through a mask means. 7. The method for manufacturing a magnetic recording medium according to claim 4, wherein the energy beam is a pulsed energy beam having a pulse width of 10 μsec or less. 8. The method for manufacturing a magnetic recording medium according to claim 1, wherein the magnetization pattern is a control magnetization pattern of a magnetic head used for recording / reproduction.