JP2002050036A - Method for forming magnetization pattern in magnetic recording medium, magnetic recording medium, magnetic recording device and device for forming magnetization pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for formation of a magnetization pattern to efficiently and more accurately form a fine magnetization pattern in the techniques to form a magnetization pattern in a magnetic recording medium by combining local heating and application of an external magnetic field, and to provide a magnetic recording medium recordable in higher density and a magnetic recording device in a short time at a low cost. SOLUTION: The magnetization pattern is formed in a magnetic recording medium having a magnetic thin film on a substrate by a process of locally heating the magnetic thin film and a process of applying an external magnetic field on the magnetic thin film. In the method, when the magnetic thin film is locally heated by irradiating the medium surface with energy rays, patterned energy rays having the distribution of intensity according to the magnetization pattern to be formed are made to irradiate as a reduced image on the medium surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a magnetic pattern of a magnetic recording medium used in a magnetic recording apparatus, a magnetic recording medium and a magnetic recording apparatus, and a magnetic pattern forming apparatus. The present invention relates to a method for forming a magnetic pattern of a magnetic recording medium, a magnetic recording medium, a magnetic recording device, and a magnetic pattern forming device suitable for performing recording and reproduction on a magnetic recording medium.

[0002]

2. Description of the Related 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. It is also being used as a device. A magnetic disk device (hard disk drive) generally includes a shaft for fixing one or more magnetic disks in a skewered manner, a motor for rotating the magnetic disk joined to the shaft via a bearing, and a recording and / or recording device. A magnetic head used for reproduction, an arm to which the head is attached, and an actuator that can move the head to an arbitrary position on the magnetic recording medium via the head arm,
The recording / reproducing head moves over the magnetic recording medium with 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 forms a NiP layer on a surface of a substrate made of an aluminum alloy or the like, and performs a required smoothing process.
After a texturing process or the like is performed, a metal underlayer, a magnetic layer (information recording layer), a protective layer, a lubricating layer, and the like are sequentially formed thereon. Alternatively, it is manufactured by sequentially forming a metal underlayer, a magnetic layer (information recording layer), a protective layer, a lubricating layer, and the like on the surface of a substrate made of glass or the like. 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.

The protective layer on the magnetic layer prevents the magnetic layer from being damaged due to the collision of the floating magnetic head or the sliding with the contact type head, and the lubricating layer provides lubricity between the magnetic head and the medium. With this configuration, recording / reproduction with a flying / contact magnetic head is possible. Since the distance between the magnetic layer and the head can be reduced by using the floating type / contact type head, information can be recorded at a much higher density than an optical disk or a magneto-optical disk using a head of another type.

The speed of increasing the density of magnetic recording media is increasing year by year, and there are various techniques for achieving this. For example, improvements such as reducing the flying height of the magnetic head, employing 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 distance between the two. For example, 100Gb
To realize it / inch ² , the track density is 10
0 ktpi or more is required.

On each track, a control magnetization pattern for controlling the magnetic head is formed. For example, it is a signal used for position control of the magnetic head or a signal used for synchronization control. When the number of tracks is increased by reducing the interval between information recording tracks, a signal used for controlling the position of the data recording / reproducing head (hereinafter, may be referred to as a “servo signal”) is also adjusted in the radial direction of the disk. On the other hand, it must be provided densely, that is, more, so that precise control can be performed. Also, there is a demand for an area other than used for data recording, that is, an area used for a servo signal or a gap portion between the servo area and the data recording area to reduce the data recording area to increase the data recording capacity. large. For this purpose, it is necessary to increase the output of the servo signal and the accuracy of the synchronization signal.

Conventionally, a widely used method is to make a hole near the head actuator of a drive (magnetic recording device), insert a pin with an encoder into the hole,
The actuator is engaged with the pins, and 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, a technique has been proposed in which a magnetic disk is irradiated with a laser beam to locally deform the disk surface to form physical unevenness, thereby forming an unevenness servo signal. But,
Problems that the flying head becomes unstable due to the unevenness and adversely affects recording / reproducing, a laser beam having a large power must be used to form the unevenness, it is costly, and it takes time to form the unevenness one by one. was there. For this reason, a new servo signal forming method has been proposed.

One example is a method in which a servo pattern is formed on a master disk having a magnetic film with a high coercive force, the master disk is brought into close contact with a magnetic recording medium, and a magnetization pattern is transferred by applying an auxiliary magnetic field from outside (USP).
5,991,104).

Another example is a method of preliminarily magnetizing a medium in one direction, patterning a soft magnetic film having a high magnetic permeability and a low coercive force on a master disk, bringing the master disk into close contact with the medium, and applying an external magnetic field. It is. The soft magnetic layer functions as a shield, and a magnetization pattern is transferred to an unshielded region (Japanese Patent Laid-Open No. 50-60212). Alternatively, the medium is magnetized in one direction in advance, a ferromagnetic film such as a soft magnetic material is provided on the master disk and patterned, and the master disk is brought into close contact with the medium and a magnetic field is applied from the outside to magnetize the soft magnetic material. (See Japanese Patent Application Laid-Open No. 10-45544, Digest of InterMag 2000, GT-06). Regardless of whether it is a shield or a magnetic recording source, each technique uses a master disk and forms a magnetization pattern on a medium by a strong magnetic field.

Generally, the strength of the magnetic field depends on the distance,
When a magnetization pattern is recorded by a magnetic field, the pattern boundary tends to be unclear due to a leakage magnetic field. Therefore,
In order to minimize the leakage magnetic field, it is essential that the master disk and the medium are in close contact. Further, as the pattern becomes finer, it is necessary to make the pattern tightly contacted without any gap. Usually, both are pressed by vacuum suction or the like. In addition, as the coercive force of the medium increases, the magnetic field used for transfer increases, and the leakage magnetic field also increases.

Therefore, the above technique is easy to apply to a flexible floppy (registered trademark) disk which is easily pressed and a magnetic disk having a low coercive force which does not need to be tightly adhered. Coercive force for density recording is 300
It is very difficult to apply it to a magnetic disk having more than 0 Oe.

In other words, a magnetic disk having a hard substrate may cause a defect in a medium when fine dust or the like is sandwiched in close contact, or may damage an expensive master disk. In particular, in the case of a glass substrate, there has been a problem that the adhesion becomes insufficient due to the interposition of dust, so that magnetic transfer cannot be performed, and a crack occurs in the magnetic recording medium.

According to the technique described in Japanese Patent Application Laid-Open No. 50-60212, a pattern having an oblique angle with respect to the track direction of a disk can be recorded, but only a pattern having a weak signal intensity can be formed. There was no problem. For a high-coercivity magnetic recording medium having a coercive force of 2000 to 2500 Oe or more, a ferromagnetic material (shielding material) for the pattern of the master disk is made of a saturated magnetic flux such as permalloy or sendust in order to secure the magnetic field strength of transfer. A high density soft magnetic material must be used. However, in the oblique pattern, the magnetic field of the magnetization reversal is in the direction perpendicular to the gap formed by the ferromagnetic layer of the master disk, and the magnetization cannot be tilted 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 difficult 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.

On the other hand, Japanese Patent Application No. 2000-13460
No. 8 and Japanese Patent Application No. 2000-134611 form 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 the medium is locally heated by irradiating an energy ray or the like through a patterned mask, and an external magnetic field is applied while lowering the coercive force of the heated area, thereby applying a magnetic field to the heated area. Recording by an external magnetic field is performed to form a magnetization pattern.

According to the present technology, 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 since no information is recorded even when a magnetic field is applied to the area other than the heated area, 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 the present technology, 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.

[0016]

SUMMARY OF THE INVENTION As described above, Japanese Patent Application No.
00-134608 and Japanese Patent Application No. 2000-134611
The magnetic pattern forming technology described in the specification of No. 1 is an excellent technology that 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. .

In the present technology, since the accuracy of the magnetization pattern is determined to some extent by the patterning accuracy of the mask, it is necessary to perform fine processing of the mask with high accuracy in order to effectively utilize the present technology. When the magnetization pattern is further refined to a unit of 1 to 2 μm or submicron, the mask cannot be patterned with high accuracy due to the limit of processing accuracy,
In addition, the alignment accuracy between the mask and the medium is deteriorated, and there is a possibility that a magnetization pattern with sufficient accuracy cannot be obtained.

Accordingly, the present invention relates to a technique for forming a magnetization pattern on a magnetic recording medium by combining local heating and application of an external magnetic field, and a method and a method for forming a fine magnetization pattern efficiently and more precisely. It is an object of the present invention to provide a magnetic recording medium and a magnetic recording device capable of higher density recording in a short time and at low cost.

[0019]

According to a first aspect of the present invention, there is provided a method of forming a magnetic pattern on a magnetic recording medium, comprising: locally heating the magnetic thin film on a magnetic recording medium having a magnetic thin film on a substrate. And a step of applying an external magnetic field to the magnetic thin film, wherein the magnetic thin film is locally heated by irradiating the surface of the medium with energy rays. A reduced energy beam having a patterned intensity distribution on the medium surface. According to a second aspect of the present invention, in the method for forming a magnetic pattern of a magnetic recording medium according to the first aspect, the energy beam is changed into a patterned energy beam by changing an intensity distribution according to a magnetic pattern to be formed. In this case, a reduced image is formed on the medium surface.

According to a third aspect of the present invention, there is provided a method for forming a magnetic pattern on a magnetic recording medium according to the second aspect, wherein the intensity of the energy beam is increased by passing the energy beam through a mask having a transmission portion partially transmitting the energy beam. It is characterized in that the distribution is changed. According to a fourth aspect of the present invention, there is provided a magnetic pattern forming method for a magnetic recording medium according to any one of the first to third aspects, wherein a minimum width of the magnetic pattern is 2 μm or less. According to a fifth aspect of the present invention, there is provided a magnetic pattern forming method for a magnetic recording medium according to any one of the first to fourth aspects, wherein the magnetic pattern is a servo pattern or a servo pattern for controlling a position of a recording / reproducing head. It is characterized by including a reference pattern for recording.

According to a sixth aspect of the present invention, there is provided a magnetic pattern forming method for a magnetic recording medium according to any one of the first to fifth aspects, wherein the magnetic recording medium is a magnetic disk having a diameter of 65 mm or less. . According to a seventh aspect of the present invention, there is provided a method for forming a magnetization pattern on a magnetic recording medium according to any one of the first to sixth aspects, wherein an external magnetic field is applied to uniformly magnetize the magnetic thin film in a desired direction in advance. At the same time as heating the thin film locally, an external magnetic field is applied to magnetize the heating portion in a direction opposite to the desired direction to form a magnetized pattern.

According to a eighth aspect of the present invention, in the method for forming a magnetic pattern of a magnetic recording medium according to any one of the first to seventh aspects, the energy beam is a pulse laser emitted from a pulse laser light source. And According to a ninth aspect of the present invention, in the method for forming a magnetic pattern of a magnetic recording medium according to any one of the first to eighth aspects, the temperature at which the magnetization of the magnetic thin film disappears is 100 ° C. or higher. . According to a tenth aspect of the present invention, there is provided the magnetic pattern forming method for a magnetic recording medium according to any one of the first to ninth aspects, wherein the magnetic recording medium has a magnetic thin film and a protective layer sequentially on a substrate. It is characterized by.

According to the eleventh aspect of the present invention, there is provided a method of forming a magnetization pattern on a magnetic recording medium, comprising the steps of:
The thickness of the protective layer is not more than 50 nm.
According to a twelfth aspect of the present invention, there is provided a method for forming a magnetization pattern on a magnetic recording medium according to the tenth or eleventh aspect, wherein the protective layer is made of diamond-like carbon. A magnetic pattern forming method for a magnetic recording medium according to a thirteenth aspect of the present invention is the method according to any one of the tenth to twelfth aspects, wherein the magnetic recording medium has a lubricating layer on a protective layer. I do. According to a fourteenth aspect of the present invention, there is provided the method of forming a magnetization pattern for a magnetic recording medium according to the first aspect.
3. The method according to claim 3, wherein the surface roughness Ra of the magnetic recording medium is 3 nm or less.

A magnetic recording medium according to a fifteenth aspect of the present invention is characterized in that a magnetic pattern is formed by the method according to any one of the first to fourteenth aspects. A magnetic recording device according to a sixteenth aspect of the present invention provides a magnetic recording medium, a driving unit that drives the magnetic recording medium in a recording direction, a magnetic head including a recording unit and a reproducing unit, and 16. A magnetic recording apparatus comprising: a relative moving means; and a recording / reproducing signal processing means for inputting a recording signal to a magnetic head and outputting a reproducing signal from the magnetic head, wherein the magnetic recording medium is a magnetic recording medium according to claim 15. It is a recording medium.

According to a seventeenth aspect of the present invention, in the magnetic recording device of the sixteenth aspect, after assembling the magnetic recording medium into the device, the magnetization pattern is reproduced by a magnetic head to obtain a signal. A servo burst signal is recorded by the magnetic head as a reference. An apparatus for forming a magnetic pattern of a magnetic recording medium according to claim 18 of the present invention comprises:
An apparatus for forming a magnetic pattern by a step of locally heating a magnetic thin film by irradiating an energy beam and a step of applying an external magnetic field to the magnetic thin film, comprising: a medium holding unit for holding a magnetic recording medium; An external magnetic field applying means for applying an external magnetic field to the medium, an energy ray source for emitting an energy ray, and a mask means for changing an intensity distribution of the energy ray emitted from the energy ray source according to a magnetization pattern to be formed. And an image forming means disposed between the mask means and the magnetic recording medium, for reducing and forming the energy beam having the changed intensity distribution on the medium surface.

According to a nineteenth aspect of the present invention, there is provided the magnetic pattern forming apparatus for a magnetic recording medium according to the eighteenth aspect, wherein
It is characterized in that the mask means is a mask having a transmission portion that partially transmits energy rays. A magnetic pattern forming apparatus for a magnetic recording medium according to a twentieth aspect of the present invention is the apparatus according to the eighteenth or nineteenth aspect, wherein the energy ray source is a pulse laser light source. According to a twenty-first aspect of the present invention, a magnetic pattern forming apparatus for a magnetic recording medium according to any one of the eighteenth to twentieth aspects further comprises a condenser lens between the energy ray source and the mask means. .

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a magnetic pattern of a magnetic recording medium according to the present invention (claim 1) includes a step of locally heating a magnetic thin film on a magnetic recording medium having a magnetic thin film on a substrate. Applying a magnetic field to a magnetic thin film, wherein the magnetic thin film is locally heated by irradiating an energy ray to a surface of the medium. A patterned energy beam having an intensity distribution is reduced and imaged on the medium surface. According to this, since local heating and application of an external magnetic field are combined in forming a magnetization pattern, it is not necessary to use a strong external magnetic field as in the related art. Then, even if a magnetic field is applied to a region other than the heating region, the region is not magnetized, so that magnetic domain formation can be limited to the heating region. For this reason, a magnetic domain boundary becomes clear, and a magnetization transition width is small, a magnetization transition at a magnetic domain boundary is very steep, and a pattern with high output signal quality can be formed. If conditions are selected, the magnetization transition width can be made 1 μm or less. In addition, since it is not necessary to press the medium and the master disk by pressure as in the related art, there is no risk of damaging the medium or the mask and increasing defects of the medium. According to the present technology, a magnetization pattern oblique to a track can also be favorably formed. In addition, since the energy beam is used for local heating, the size and power of the portion to be heated can be easily controlled, and the magnetization pattern can be formed with high accuracy.

Further, according to the present invention, since a patterned energy ray having an intensity distribution corresponding to a magnetization pattern to be formed is reduced on the medium surface to form an image on the medium surface, the energy beam is focused by an objective lens and then masked. Compared with the case of passing through the means, that is, the proximity exposure, the precision of the magnetization pattern is not limited by the patterning precision and alignment precision of the mask, and a finer magnetization pattern can be formed with high precision. 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. The energy ray emitted from the light source changes the intensity distribution through the mask means, and forms a reduced image on the medium surface through the 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. The mask means may be any as long as it forms the intensity (shade) of the energy beam on the medium according to the magnetization pattern to be formed. For example, there are a photomask in which an energy ray transmitting portion and a non-transmitting portion are created according to a pattern, and a hologram mask in which a hologram is recorded so that a specific pattern is formed on a medium.

In the present technology, an image forming means is provided between the mask means 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. However, the present invention also solves this problem. In other words, it is preferable that the medium surface on which the magnetization pattern is formed has a large temperature difference between when the pulsed energy beam is irradiated and when the pulsed energy beam is not irradiated, 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.

By using the mask means, a complicated magnetization pattern can be formed simply and in a short time by one irradiation. Also,
Special patterns that are difficult to record with a magnetic head can be easily formed. For example, in a phase servo method for 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 continuous pattern in the radial direction or a pattern oblique to the radius is difficult to make 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 complicated calculations and complicated device configurations. Even if the masking means does not cover the entire surface of the magnetic disk, the masking means may be of a size including a repetition unit of the magnetization pattern, and can be used by moving it.

As the mask means, it is preferable to use a mask having a transmission part that partially transmits the energy beam, that is, a so-called photomask. Since a photomask is easy to form and good processing accuracy can be easily obtained, a high-precision mask can be obtained and a high-precision magnetization pattern can be formed. It is preferable to pass a condenser lens before the mask means, since the intensity distribution of the energy rays can be made uniform and the energy rays can be efficiently collected on the imaging lens. The present technology can be applied to a magnetization pattern of any size or shape as long as the beam diameter of the energy ray and the intensity of the external magnetic field allow. 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, it is 1 μm or less. There is no lower limit of the pattern that can be formed, and a fine pattern can be theoretically formed up to the wavelength limit of energy rays. For example, it is about 100 nm by an excimer laser or the like.

Further, since the present technology can form a finer magnetized pattern by reducing and forming an image, it can be applied to formation of a servo pattern used for position control of a data recording / reproducing head or a reference pattern for recording the servo pattern. Great effect. The servo pattern is a pattern for generating a servo signal for tracking a recording / reproducing head on a data track on a magnetic recording medium. The servo pattern needs to be formed with a finer pattern than the data pattern and with high precision. If the servo pattern is coarse, the position control of the head is also coarse, so it is impossible to theoretically record a data pattern that is finer and more precise than the servo pattern. Is done.

The present technology is suitable for forming a simple repetitive magnetization pattern because of using a mask means, and it is possible to form a finer magnetization pattern with high precision by reducing an image. high. Even if the servo pattern is a special or complicated pattern, it can be easily formed by using a mask. The effect is also great when applied to the formation of a reference pattern for generating a reference signal, which is used by a drive or the like to record the servo pattern, instead of the servo pattern itself. Since a highly accurate servo pattern or reference pattern can be obtained, the track density is 40 kT for high-density recording.
The effect is high when applied to a magnetic recording medium having a PI or higher.

As described above, even in the case where the magnetization pattern includes a pattern extending obliquely to the track, the signal strength can be increased according to the present invention. The present invention is preferred. The pattern extending obliquely is, for example, a pattern having an inclination from the reference line when a direction perpendicular to the head running direction is used as the reference line. Preferably, if the inclination from the reference line is within ± 45 °, a signal sufficient for use as a servo signal can be obtained. Alternatively, the magnetization pattern formed by the present technology may be used for a defect inspection of a medium. Since the recording process of the defect inspection can be omitted, the manufacturing time can be shortened, leading to cost reduction, and the density of the defect inspection can be increased.

In the present technology, since a reduced image is formed by the imaging means after passing through the mask means, a finer pattern can be formed by increasing the reduction ratio. However, since the beam diameter of the energy beam is reduced by the narrowing down, the pattern area that can be formed at one time is reduced. For this reason, the present technology is suitable for high-density and small-diameter magnetic disks, particularly magnetic disks having a diameter of 65 mm or less.

In general, the smaller the diameter of the magnetic disk, the larger the required recording capacity and the higher the recording density, despite the smaller recording area. It is more preferably used for a magnetic disk having a diameter of 1.8 inches or less, particularly preferably 1 inch or less. For example, it is possible to record data and the like at a time on a very small magnetic disk having a diameter of about 1 inch or less. In particular, in the case of a perpendicular magnetic disk, an external magnetic field can be easily applied to the entire disk, so that data can be recorded on the entire surface in an instant. However, application to a magnetic recording medium having a large diameter such as 3.5 inches is also possible. By irradiating the magnetic pattern of multiple tracks or multiple sectors collectively by making the beam shape a horizontally elongated ellipse or the like, the recording efficiency is increased, and the servo recording time is longer than the servo signal writing by the conventional head It can be shortened and the accuracy will increase.

In the present invention, it is preferable to irradiate the medium with an energy beam while scanning the medium, since a beam with a small diameter can irradiate a wide area in a short time. For example,
A part or all of the energy beam irradiation optical system may be placed on a slider and moved to scan the beam. Alternatively, a galvanometer and an f-θ lens may be used.
The medium can be scanned by making the energy ray incident on the f-θ lens while changing the angle as needed through a galvanometer. In order to scan a wide area in as short a time as possible, it is preferable that the energy rays generate short pulses at a high speed.

In the present invention, various combinations of local heating and application of an external magnetic field are conceivable. Preferably, an external magnetic field is applied to magnetize the magnetic thin film uniformly in a desired direction in advance, and then the magnetic thin film is locally applied. At the same time as heating, an external magnetic field is applied to magnetize the heating portion in a direction opposite to the desired direction to form a magnetized pattern. According to this, since the magnetic domains opposite to each other are clearly formed, the signal intensity is strong and C /
A magnetization pattern with good N and S / N is obtained.

As the energy ray, it is sufficient that the surface of the recording layer can be partially heated, but a laser is preferable because irradiation of an unnecessary part with the energy ray can be prevented. In order to make the magnetization transition width steep, it is preferable to use a pulsed laser which has a large temperature difference between when the energy beam is irradiated and when it is not irradiated, and in which heat is hardly accumulated. The continuous laser may be pulsed by an optical component, but it is particularly preferable to use a pulsed laser light source. The pulse laser light source oscillates the laser intermittently in a pulsed manner, and can irradiate a laser having a high power peak value in a very short time, so that heat accumulation hardly occurs.

The magnetic recording medium used in the present invention preferably has a higher temperature at which the magnetization of the magnetic thin film disappears in order to keep the magnetization stable even 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.
For this reason, the magnetization extinction temperature is preferably 100 ° 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.

Preferably, the saturation magnetization is set to 50 emu / cc or more in order to magnetically detect a signal with an MR, GMR, TMR head or the like. In this case, since the influence of the demagnetizing field is large, it is desirable that the pulse width be as narrow as possible so that the temperature of the portion where the magnetization is reversed by the heating and the external magnetic field drops sharply. More preferably, 100 emu / cc
Above. However, if it is too large, it is difficult to form a magnetized pattern.

Further, since a higher coercive force at room temperature enables higher density recording, it is preferably 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, since a magnetic pattern is formed by heating a magnetic thin film and sufficiently lowering the coercive force, the coercive force is large. High application effect to media. In addition, it is preferable to provide a protective layer in order to prevent damage to the medium due to the magnetic pattern forming process and collision with the magnetic head during recording and reproduction. In order to reduce the distance between the magnetic thin film and the head during recording and reproduction, the film thickness is preferably set to 50 nm or less. When there are a plurality of magnetic thin films, a protective layer may be provided on the magnetic thin film closest to the surface. Preferably, the protective layer is made of diamond-like carbon. It not only plays a role in preventing the magnetic thin film from being damaged by energy rays, but also becomes extremely resistant to damage to the magnetic thin film by the head.

It is preferable to provide a lubricating layer between the head and the medium in order to provide lubrication. The magnetic pattern forming method of the present invention may be performed before or after the formation of the lubricating layer, but does not hinder the formation of the magnetic pattern,
Alternatively, in order to prevent sticking of the magnetic head, the thickness of the lubricating layer is preferably thin, and is preferably 10 nm or less. Furthermore,
In order not to impair the running stability of the flying / contact head,
It is preferable to maintain the surface roughness Ra of the medium after forming the magnetization pattern at 3 nm or less. The medium surface roughness Ra is the surface roughness of the medium not including the lubricating layer.
This is a value calculated according to 601. More preferably, 1.
The thickness is set to 5 nm or less.

More 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 not containing the lubricating layer, and is a value calculated according to Ra calculation after measuring with a stylus type surface roughness meter at a measurement length of 2 mm. More preferably, the thickness is 3 nm or less.
Further, it is preferable that the substrate of the medium is a hard substrate made of glass, because the amount of heat given by the energy rays dispersed by thermal diffusion is small and energy can be used efficiently. In addition, there is also an effect that the resolution of the magnetization pattern is increased due to the small heat diffusion. When the present invention is applied to a glass substrate, it is also resistant to entrapment of dust and the like, and the magnetic recording medium is not cracked or the master is not damaged due to the hardness of the substrate surface, which is preferable.

In the magnetic recording medium in which the magnetization pattern is formed by the above method, the precision of the magnetization pattern is not limited by the patterning accuracy and the alignment accuracy of the mask. Are formed with high accuracy. Then, a pattern is formed in which the magnetization transition width is small, the magnetization transition at the boundary of the magnetic domain is very steep, and the quality of the output signal is high. In addition, since it can be easily manufactured in a very short time and does not adhere to the master disk unlike the related art, there are few scratches and defects. In particular, as the recording density increases, not only is it difficult to write servo signals, but also servo recording is a major cause of cost increase. Therefore, applying the present invention to a medium for high-density recording has a great effect. In the case of a perpendicular magnetic recording medium, since the application of a magnetic field is easy, the present invention can be applied more easily. By incorporating the present technology into a production line of a magnetic recording medium, a medium on which a high-precision magnetization pattern for head control is formed can be produced in a short time and at low cost.

Next, the magnetic recording apparatus of the present invention (claim 1)
6) a magnetic recording medium described above, a driving unit for driving the magnetic recording medium in the recording direction, a magnetic head including a recording unit and a reproducing unit, and means for moving the magnetic head relative to the magnetic recording medium; It has a recording / reproducing signal processing means for inputting a recording signal to the magnetic head and outputting a reproducing signal from the magnetic head. As a magnetic head, a floating / contact magnetic head is usually used to perform high-density recording. Since a magnetic recording medium on which a magnetization pattern such as a fine and highly accurate servo pattern is formed is used, such a 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.

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. Also, 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. Is easily returned to a desired position, and therefore, a magnetic recording apparatus in which signals by both writing methods are present has high reliability.

Next, a magnetic pattern forming apparatus according to the present invention comprises a medium holding means for holding a magnetic recording medium, an external magnetic field applying means for applying an external magnetic field to the magnetic recording medium, and an energy beam. An energy ray source, a mask means for changing an intensity distribution of an energy ray emitted from the energy ray source in accordance with a magnetization pattern to be formed, and a mask means and a magnetic recording medium. Imaging means for reducing and imaging the changed energy rays on the medium surface.

According to this, since the local heating by the local heating means and the application of the external magnetic field by the external magnetic field applying means are combined in forming the magnetization pattern, the magnetization can be performed without using a strong external magnetic field applying means as in the prior art. A pattern can be formed. Then, even if a magnetic field is applied to a region other than the heating region, the region is not magnetized, so that magnetic domain formation can be limited to the heating region. Therefore, a pattern in which the magnetic domain boundaries are clear, the magnetization transition width is small, the magnetization transition at the magnetic domain boundaries is very steep, and the output signal quality is high can be formed. If conditions are selected, the magnetization transition width can be made 1 μm or less.

According to the present technology, unlike the conventional magnetic transfer technology, there is no need to integrally press the medium and the master disk by vacuum suction or the like, so that there is no need to provide a complicated medium holding means. Also, conventionally, it has been necessary to repeat the suction and release of the mask means every time the medium is replaced. However, according to the present technology, it is not necessary to remove the mask means once attached.
Further, since the disk and the mask means are separated from each other, handling such as mounting and removing the disk and the mask means is easy. In addition, since an energy beam is used for local heating, it is easy to control a portion to be heated and power. Further, since the reduction imaging technique is used, a finer magnetized pattern can be formed with higher accuracy if the alignment accuracy of the mask means with respect to the medium and the patterning accuracy of the mask means are the same as compared with the conventional transfer apparatus. When a mask having a transmission portion that partially transmits an energy ray, that is, a so-called photomask is used as the mask means, it is easy to produce and good processing accuracy is easily obtained.
An accurate mask can be obtained, and a more accurate magnetization pattern can be formed.

As the energy ray source, it is sufficient that the recording layer surface can be partially heated, but a laser light source is preferable because it can prevent the irradiation of unnecessary parts with energy rays. In order to make the magnetization transition width steep, a pulse-shaped laser which has a large temperature difference between when the energy beam is irradiated and when the energy beam is not irradiated and in which heat is hardly accumulated is preferable. The continuous laser may be pulsed by an optical component, but it is particularly preferable to use a pulsed laser light source. The pulse laser light source oscillates the laser intermittently in a pulsed manner, and can irradiate a laser having a high power peak value in a very short time, so that heat accumulation hardly occurs. If a condenser lens is provided before the mask means,
It is preferable because the intensity distribution of the energy rays can be made uniform and the energy rays can be efficiently collected on the imaging lens.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. An external magnetic field is applied to magnetize the magnetic thin film uniformly in advance, and then a local magnetic pattern is formed by applying an external magnetic field in the opposite direction while heating locally. 1 and 2 show an example of a disk holding unit and a magnetic field applying unit of the magnetization pattern forming apparatus of the present invention. As shown in the cross-sectional view of FIG. Adsorbed and fixed.
The magnetic disk 1 has a magnetic thin film 22 a on a hard substrate 21.
22b.

On one surface of the disk 1, a first magnetic field applying means 4 comprising a yoke 5 and a permanent magnet 6 is arranged. FIG. 1B is a schematic view of FIG. 1A viewed from the direction of the arrow. The first magnetic field applying means 4 has a long shape in the radial direction of the disk 1, and includes permanent magnets 6a and 6 such as NdFe magnets.
The magnetic poles are fixed on the yoke 5 with the magnetic poles being opposite to each other, and a magnetic field is generated so as to connect the N pole of the magnet 6a and the S pole of the magnet 6b. By making this magnetic field larger than the coercive force of the disk 1, the magnetic thin film 22a on the upper surface side of the magnetic disk 1 is magnetized in the in-plane circumferential direction. When the spindle 2 is rotated with the first magnetic field applying means 4 fixed in this state, the magnetic disk 1 rotates in the direction of the arrow, and a magnetic field is applied to the entire magnetic thin film 22a to be magnetized in one direction. Next, the first magnetic field applying means 4 is retracted from above the disk.

Next, an external magnetic field in the opposite direction is applied to the magnetic disk 1 while locally heating. As shown in the sectional view of FIG. 2, the yoke 9 and the permanent magnet 10
Is provided. The magnetic field generated by the second magnetic field applying means 8 is opposite to the first magnetic field applying means 1 and is small, and is equal to or less than the coercive force of the disk 1. Other configurations and shapes may be the same as those of the first magnetic field applying unit 4.

The pulse laser 11 emitted from a light source (not shown) and passing through the condenser lens reaches the photomask 12. The photomask 12 has an opaque layer 14 formed on a substrate 13 transparent to a laser wavelength, corresponding to a magnetization pattern to be formed.
Is transmitted, the intensity distribution is changed according to the magnetization pattern, and a spatially patterned laser is obtained. On the photomask 12, a material opaque to energy rays, such as a metal such as Cr, is formed by sputtering on a substrate such as quartz glass or soda lime glass, and a photoresist is applied thereon. By etching etc.
Desired transmission parts and non-transmission parts can be created.

The laser 11 reaches the imaging lens 15, where it is narrowed down to a desired size, and the density of the laser similar to the pattern formed on the photomask 12 is reduced and imaged on the magnetic disk 1. The imaging part is heated, and the magnetic thin film 2
2a is heated to near the magnetization extinction temperature. At the same time, since the external magnetic field is applied by the second external magnetic field applying means 8 smaller than the coercive force of the magnetic thin film 22a of the magnetic disk 1, only the temperature rising portion is magnetized in the direction of the external magnetic field. Next, the laser irradiation is stopped, and the temperature-raising section is cooled to room temperature and the magnetization is stabilized. Since the second external magnetic field has a direction opposite to that of the first external magnetic field when magnetized uniformly first, a magnetization pattern is formed on the magnetic thin film 22a as described above.

When a magnetic pattern is to be formed in another area of the magnetic thin film 22a, the spindle 2 is rotated while the second magnetic field applying means 8 is fixed to rotate the magnetic disk 1 by a predetermined angle, and the photomask 12 and the The heating and the application of the magnetic field may be performed by moving the optical system component to a predetermined position. The minimum beam diameter φ to be narrowed down by the imaging lens is determined by the numerical aperture NA of the imaging lens and the wavelength λ of the energy beam to be used.
There is a relationship of 1.22 × (λ / NA). That is, when a finer pattern is to be formed on the magnetic recording medium, λ
Must be reduced or the NA must be increased. When narrowing down with a condenser lens in advance, the NA of the condenser lens is also taken into consideration.

FIG. 3 shows an example of the configuration of an optical system for laser irradiation used in the present invention. Pulse laser light source 41
The pulse laser 11 oscillated from the above passes through the programmable shutter 42. Programmable shutter 42
Serves to extract only the desired pulse from the light source. As the pulse laser light source 41, for example, an excimer laser or a fourth-harmonic Q-switched laser of YAG is used. The laser 11 selected by the programmable shutter 42 is
After being converted into a desired power by the attenuator 43, the power passes through the condenser lens 44 and reaches the photomask 12.
The condenser lens 44 generally comprises a combination of an aspheric lens 44a and a plano-convex lens 44b, has a function of making the energy intensity distribution on the mask surface uniform, and guides the energy flux to the imaging lens 15 efficiently. Next, the laser 11 changes the intensity distribution according to the magnetization pattern by the photomask 12, and then forms a reduced image on the magnetic thin film 22 a of the disk 1 through the imaging lens 15.
FIG. 4 shows another example of the configuration of an optical system for laser irradiation used in the present invention. The pulse laser 11 oscillated from the pulse laser light source 41 is supplied to a programmable shutter 42.
After passing through the attenuator 43, the beam reaches the beam expander 45. The beam expander is used to temporarily increase the beam diameter before imaging, such as when it is desired to increase the reduction projection ratio of a mask. Next, the laser 11 passes through the condenser lens 44, changes the intensity distribution according to the magnetization pattern by the photomask 12, and then forms a reduced image on the magnetic thin film 22 a of the disk 1 through the imaging lens 15.

In order to make the energy intensity distribution uniform, a homogenizer can be used instead of the condenser lens. Further, the condenser lens and the homogenizer may be used in combination. Alternatively, when these equalizing means are not used, a portion having a low energy may be blocked by a slit or the like, and only a portion having a good distribution may be used. Further, the energy beam may be shaped into a desired beam shape by a light shielding plate. FIG. 5 is a schematic view of an example of the light shielding plate. In the light shielding plate 46, a laser transmission portion 52 corresponding to a desired beam shape is formed on a substrate 51 through which the laser 11 does not transmit. Although the figure shows an example in which it is formed in a substantially sector shape, other shapes such as a substantially square shape may be used. The light-shielding plate has a function of preventing laser irradiation on an unnecessary region and preventing re-irradiation on a region where a magnetization pattern is already formed, but may be provided as necessary. The position of the mask is not limited, but is preferably immediately before or immediately after the mask.

As described above, the configuration and order of the optical system used in the present invention can be variously modified as necessary. The second external magnetic field applying means may be applied from any surface of the disk. However, in the above embodiment, the second external magnetic field applying means is disposed on the side opposite to the laser irradiation surface of the disk, so that the laser is not blocked.

Next, preferable conditions of the energy beam used in the present invention will be described. The step as the energy ray is only required to be able to partially heat the surface of the recording layer, but a laser is preferable because irradiation of the energy ray to unnecessary portions can be prevented. In particular, use of a pulse laser light source is preferred. 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), a pulsed laser light source is used. 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, the pulse laser light source accumulates energy by resonance in the light source and emits the laser at a time as a pulse, so that the peak power is very large within the pulse and then decreases. 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, the use of a pulse 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.

The wavelength of the energy ray is preferably 1100 nm or less. If the wavelength is shorter than this, the diffraction effect is small and the resolution increases, 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 means is small, so that the spacing between the mask means 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 is easy to configure. Further, the wavelength is preferably 150 nm or more. 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.
More specifically, a second harmonic (532n) of an excimer laser (248 nm) and a YAG Q-switched laser (1064 nm) is used.
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 per pulse of the pulsed energy beam is preferably 1000 mJ / cm ² or less. 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 running of the floating / contact type head may be hindered.

It is more preferably at most 500 mJ / cm ² , still more preferably at most 100 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 thin film hardly rises and magnetic transfer hardly occurs.

When the substrate used in the present invention is a metal or alloy such as Al or the like, since the heat conductivity is high, the locally applied heat spreads to a portion other than a desired portion, and may distort the magnetization pattern. Preferably, the power is in the range of 30 to 120 mJ / cm ² so as not to cause physical damage to the substrate due to excessive energy.

When the substrate is made of ceramics such as glass, the heat conduction is lower than that of Al or the like, and the heat accumulation at the pulsed energy beam irradiation site is large.
It is preferably in the range of 0 to 100 mJ / cm ² .
When the substrate is made of a resin such as polycarbonate, the power is 10 to 80 mJ 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.
/ Cm ² is preferable.

When the magnetic thin film, the protective layer, and the lubricating layer may be damaged by the energy beam, the power of the pulse energy beam is reduced and the intensity of the magnetic field applied simultaneously with the pulse energy beam is increased. Such means can also be taken. For example, in the case of an in-plane recording medium, 25 to 75% of the coercive force at room temperature is applied, and in the case of perpendicular recording, a large force of 1 to 50% is applied to lower the irradiation energy.

In irradiating the pulsed energy beam through the protective layer and the lubricating layer, it may be necessary to re-apply after the irradiation in consideration of the damage (decomposition, polymerization) of the lubricant. . It is desirable that the pulse width of the pulsed energy beam be 1 μsec or less. 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 the thermal diffusion and increase the resolution of the magnetization pattern. More preferably, it is 100 nsec or less. In this region, even when a substrate such as Al having a relatively large thermal diffusion of a metal is used, a magnetization pattern with high resolution is easily formed. That is, if importance is placed on the resolution, the shorter the pulse width, the better. Further, 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 thin film is completed.

As one type of pulsed laser, there is a laser such as a mode-locked laser capable of generating ultrashort pulses at picosecond and femtosecond levels 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 portion 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 calculated as the power per pulse (mJ /
cm ² ). When the medium has a disk shape, the direction in which the external magnetic field is applied is preferably one of a circumferential direction, a radial direction, and a direction perpendicular to the plate surface.

As means for applying an external magnetic field to the magnetic thin film, 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. When the medium is disk-shaped, 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.

In the present invention, there is sufficient spacing for the focal length between the image forming means and the magnetic recording medium. There is no fear of damage due to contact with other components due to undulation of the recording medium. Since the distance to the imaging plane is determined in advance, the distance from the medium is adjusted so as to be the distance. When forming the magnetized pattern, a light-shielding plate capable of partially shielding the energy beam is provided between the energy beam light source and the mask unit or between the mask unit and the medium, and the energy beam is reproduced. It is preferable to adopt a structure for preventing irradiation.

The light-shielding plate may be any as long as it does not transmit the wavelength of the energy ray used, and may reflect or absorb the energy ray. However, if the heat of the energy ray is absorbed, it is likely to be heated and affect the magnetization pattern.
Those having good thermal conductivity and high reflectivity are preferred. For example,
It is a metal plate of Cr, Al, Fe, or the like. When the substrate of the magnetic recording medium of the present invention is made of glass, the amount of heat given by the energy rays dispersed by thermal diffusion is small, and energy can be used efficiently, which is preferable. In addition, there is also an effect that the resolution of the magnetization pattern is increased due to the small heat diffusion. When the present invention is applied to a glass substrate, it is also resistant to entrapment of dust and the like, and the magnetic recording medium is not cracked or the master is not damaged due to the hardness of the substrate surface, which is preferable.

In order to prevent the medium from being damaged by the magnetization pattern forming process, it is preferable to provide a protective layer having a thickness of 50 nm or less on the magnetic thin film. When there are a plurality of magnetic thin films, a protective layer may be provided on the magnetic thin film near the outermost surface. More preferably, a lubricating layer having a thickness of 10 nm or less is provided on the protective layer.

In the present invention, the following aspects can be taken as a combination of the step of locally heating the magnetic thin film and the step of applying an external magnetic field to the magnetic thin film. Aspect 1: A method of forming a magnetized pattern by magnetizing a magnetic thin film uniformly in a desired direction with a strong external magnetic field before heating, and then heating and demagnetizing a desired portion to near the Curie point. According to this, the magnetization pattern can be formed most easily. In addition, since the magnetic thin film is uniformly magnetized, normal magnetic recording can be performed after forming a magnetization pattern by this method. Aspect 2: A method in which a magnetic thin film is uniformly magnetized in a desired direction by a strong external magnetic field before heating, and thereafter, a desired portion is heated to near the Curie point, and a weak magnetic field is applied and demagnetized to form a magnetization pattern. According to this, demagnetization can be completely performed, and a magnetization pattern with a large signal intensity can be obtained.

Aspect 3: A method in which a weak external magnetic field is applied simultaneously with heating to magnetize only the heating portion in the direction of the external magnetic field, thereby forming a magnetization pattern. According to this, the magnetization pattern can be formed most easily, and the external magnetic field may be weak. Aspect 4: A method of forming a magnetized pattern by magnetizing a magnetic thin film uniformly in a desired direction with a strong external magnetic field before heating and then heating a desired portion and simultaneously applying a weak magnetic field in a direction opposite to that before heating. . According to this, a magnetization pattern having the strongest signal intensity and good C / N and S / N can be obtained.

Hereinafter, each embodiment will be described. The direction of the external magnetic field of the first aspect differs depending on the type of the magnetic thin film of the magnetic recording medium. In the case of a medium in which the axis of easy magnetization is in the in-plane direction, the magnetic thin film is applied so as to be magnetized in the same direction or the opposite direction to the running direction of the data writing / reproducing head (the relative movement direction of the medium and the head). . Further, when the magnetic recording medium has a disk shape, the magnetic recording medium can be applied so as to be magnetized in the radial direction. When the axis of easy magnetization is perpendicular to the in-plane direction, the magnetic thin film is applied so as to be magnetized in any of the perpendicular directions. The strength of the magnetic field depends on the characteristics of the magnetic thin film of the magnetic recording medium, and it is preferable that the magnetic thin film is magnetized by a magnetic field at least twice the coercive force at room temperature. If it is lower than this, the magnetization may be insufficient.
However, the coercive force of the magnetic thin film at room temperature is preferably five times or less in view of the capability of the magnetizing device used for applying the magnetic field.

In the second embodiment, the direction and intensity of the external magnetic field before heating are exactly the same as those in the first embodiment. The direction of the magnetic field applied at the same time as the heating is in the direction perpendicular to the in-plane direction when the easy axis is in the in-plane direction. In-plane direction. Thus, the magnetic field is applied to erase the magnetization. The strength of the magnetic field depends on the characteristics of the magnetic thin film of the magnetic recording medium, but is smaller than the coercive force of the magnetic thin film at room temperature. Preferably, the magnetic field is at least 1/8 of the coercive force of the magnetic thin film 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, the coercive force of the magnetic thin film at room temperature is preferably not more than 1/2 times. If it is larger than this, the magnetic domains around the heating unit may be affected.

As long as the heating can be performed to a temperature at which the coercive force of the magnetic thin film is reduced, it is, for example, near the Curie temperature of the magnetic thin film. Preferably, it is heated to 100 ° C. or higher. Magnetic thin films 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 set to 400 ° C. or lower. If it exceeds this, the magnetic thin film may be deformed.

The direction of the external magnetic field at the same time as the heating in the mode 3 is as follows.
It depends on the type of the magnetic thin film of the magnetic recording medium. In the case of a medium in which the axis of easy magnetization is in the in-plane direction, the magnetic thin film is applied so as to be magnetized in the same direction or the opposite direction to the running direction of the data writing / reproducing head (the relative movement direction of the medium and the head). . Further, when the magnetic recording medium has a disk shape, the magnetic recording medium can be applied so as to be magnetized in the radial direction. When the easy axis is perpendicular to the in-plane direction,
The application is performed so that the magnetic thin film is magnetized in any of the perpendicular directions. The strength of the magnetic field is the same as the strength of the external magnetic field at the same time as the heating in the second embodiment. The heating temperature is the same as in the second embodiment. In Embodiment 4, the direction and intensity of the external magnetic field before heating are exactly the same as in Embodiment 1. The strength of the magnetic field applied simultaneously with the heating is the same as in Embodiment 2, but the direction is
The magnetic field is applied in a direction opposite to the direction of the pre-heating magnetic field so as to be locally magnetized in the opposite direction. The heating temperature is the same as in the second embodiment.

By optimizing the above-described conditions, the magnetization pattern can be formed with higher accuracy, and the quality of the output signal can be improved. That is, a pattern having a small magnetization transition width and a very steep magnetization transition at the boundary of the magnetic domain and high quality of the output signal can be formed. If conditions are selected, the magnetization transition width is 1 μm or less, further 0.5 μm or less, 0.3 μm or less.
μm or less is also possible. In the present invention, the magnetization transition width is
Pulse width (ie, half-value width) of 50% of the maximum magnetization of the reproduction signal waveform obtained by reproducing the magnetization pattern by the magnetic head
Say Furthermore, the method of the present invention is also advantageous in that the laser beam intensity can be kept low as compared with the conventional method of forming a concavo-convex pattern using a laser beam, and the floating head becomes unstable because there is no concavity and convexity. Not even.

Next, the configuration of the magnetic recording medium of the present invention will be described. 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 and reproduction, and a hard substrate is usually 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.

In the present invention, since the mask means and the medium are not in contact with each other, the adhesion between the medium having a hard substrate and the master disk is insufficient as in the conventional magnetic transfer method, and scratches and defects are generated or transferred. There is no problem that the boundaries of the magnetic domains are unclear and the PW50 tends to spread, and the effect is high when applied to a medium having a hard substrate. In particular, it is effective for a medium having a substrate easily cracked such as a glass substrate. In the manufacturing process of the magnetic disk, it is normal that the substrate is first washed and dried, and also in the present invention, before the formation,
It is desirable to perform drying. When manufacturing the magnetic recording medium of the present invention, a metal coating layer such as NiP may be formed on the substrate surface.

When the metal coating layer is formed, a method used for forming a thin film such as an electroless plating method, a sputtering method, a vacuum deposition 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 metal coating 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 500 nm or less. More preferably, it is 300 nm or less.

Further, the region where the metal coating layer is formed is desirably the entire surface of the substrate, but it is also possible to implement only a part, for example, only the region where texturing is performed. Also, concentric texturing may be applied to the surface of the substrate or the surface on which the non-magnetic metal coating layer is formed. In the present invention, concentric texturing is, for example, mechanical texturing using loose abrasive grains and texture tape or texturing using a laser beam, or by using these together, by polishing in the circumferential direction. A state in which a large number of minute grooves are formed in the circumferential direction of the substrate is referred to.

The type of free abrasive grains for mechanical texturing is most preferably diamond abrasive grains, especially those whose surfaces have been subjected to a graphitization treatment. Alumina abrasive grains are widely used as abrasive grains for mechanical texturing, but diamond abrasive grains are particularly considered from the viewpoint of in-plane orientation media that orients the easy axis of magnetization along the texturing grooves. Has extremely good performance.

It is effective for the realization of high-density magnetic recording that the flying height of the head is as small as possible. In addition, since one of the features of these substrates is excellent surface smoothness, 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 substrate and the magnetic thin film layer. The underlayer is preferably made of Cr as a main component for the purpose of refining the crystal and controlling the orientation of the crystal plane. As the material of the underlayer containing Cr as a main component, in addition to pure Cr, Cr, V, Ti, M may be used for the purpose of crystal matching with the recording layer.
o, Zr, Hf, Ta, W, Ge, Nb, Si, Cu,
An alloy containing one or more elements selected from B, Cr oxide, and the like 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 varies 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. Substrate heating may or may not be performed during the formation of the underlayer mainly composed of Cr. A soft magnetic layer may be provided on the underlayer between the recording layer and the recording layer, if necessary. In particular, the effect is large and is preferably used for a keeper medium having little magnetization transition noise or a perpendicular recording medium having magnetic domains perpendicular to the medium plane.

The soft magnetic layer only needs to have a relatively high magnetic permeability and a small loss, but NiFe or an alloy to which Mo or the like is added as a 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 data recording, it is generally preferable that the maximum magnetic permeability is about 10 to 1,000,000 (H / m). Alternatively, a CoCr-based intermediate layer may be provided on the Cr underlayer. Next, a recording layer (magnetic thin film) 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, the substrate may or may not be heated.

As the recording layer, a Co alloy magnetic film, TbF
A rare earth magnetic film represented by eCo, a transition metal and 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 is usually used.
And CoNi, CoSm, CoCrTa, CoNiCr,
C commonly used as a magnetic material such as CoCrPt
An o-alloy magnetic material can be used. These Co alloys are further added with N
A material to which an element such as i, Cr, Pt, Ta, W, or B or a compound such as SiO ₂ is added may be used. 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. Further, it is preferably 50 nm or less, more preferably 30 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, the transition metal and noble metal based laminated film on which perpendicular magnetic recording can be performed can be made of a general magnetic material. For example, Co / Pd, Co / Pt, Fe
/ Pt, Fe / Au, Fe / Ag and the like. The transition metal and the noble metal in these laminated film materials need not be particularly pure, and may be an alloy mainly containing them. The thickness of the laminated film is arbitrary, but is usually 5 to 1000.
nm. Also, a laminate of three or more materials may be used as necessary.

In the present invention, the magnetic thin film as the recording layer retains its magnetization at room temperature and is demagnetized when heated, or magnetized by applying an external magnetic field simultaneously with heating. The coercive force of the magnetic thin film 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 thin film to 2000 Oe or more, a medium that can maintain small magnetic domains and is suitable for high-density recording is obtained. More preferably, it is 3000 Oe or more.

In the conventional magnetic transfer method, it was difficult to perform transfer on a medium having a very high coercive force. Application to a medium having a large magnetic force is preferable.
However, it is preferably 20,000 Oe or less. 200
If it exceeds 00 Oe, a large external magnetic field is required for collective magnetization, and normal magnetic recording may be difficult.

The magnetic thin film 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. Further, the temperature is preferably 700 ° C. or less. This is because if the magnetic thin film is heated to an excessively high temperature, it 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 magnetic recording medium having a high coercive force for high density, and it is difficult to generate a magnetization pattern having a high magnetic field strength. And the half-value width also increases. Even in-plane recording media suitable for such a high recording density,
According to this method, a good magnetization pattern can be formed.
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 it is 100 emu / cc or more. However, if it is too large, it is difficult to form a magnetized pattern. If the magnetic recording medium is a perpendicular magnetic recording medium and 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 magnetic demagnetization, which causes noise. It worsens the half width. But,
In the present invention, good recording can be performed on these media by using a soft magnetic underlayer.

In the present invention, it is preferable to form a protective layer on the magnetic thin film. That is, the outermost surface of the medium is covered with the hard protective layer. The protective layer functions to prevent the magnetic thin film from being damaged by being caught between the head and a mask such as a collision or dust / dust. When the control magnetic pattern forming method using a mask is applied as in the present invention, the method also has a function of protecting the medium from contact with the mask. When there are a plurality of magnetic thin films, a protective layer may be provided on the magnetic thin film near the outermost surface. The protective layer may be provided directly on the magnetic thin film, or may have another layer interposed therebetween as required.

As the protective layer, a carbonaceous layer such as carbon, hydrogenated carbon, nitrogenated carbon, amorphous carbon, or SiC, or a hard material such as SiO ₂ , Zr ₂ O ₃ , SiN, or TiN can be used. It may be transparent or opaque. In terms of impact resistance and lubricity, a carbonaceous protective film is preferable, and diamond-like carbon is particularly preferable. It not only plays a role in preventing the magnetic thin film from being damaged by energy rays, but also becomes extremely resistant to damage to the magnetic thin film by the head.

A part of the energy ray is also absorbed by the protective layer, and serves to locally heat the magnetic thin film by heat conduction. For this reason, if the protective layer is too thick, the control magnetization pattern may be blurred due to heat conduction in the lateral direction. Further, it is preferable that the thickness be thin in order to reduce the distance between the magnetic thin film and the head during recording and reproduction. Therefore, it is preferably 50 nm or less, more preferably 30 nm or less, and still 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.

Further, the protective layer may be composed of two or more layers. It is preferable to provide a protective layer immediately above the magnetic layer with a layer containing Cr as a main component, since the effect of preventing oxygen from permeating the magnetic layer is high. More preferably, a lubricating layer is formed on the protective layer. It has a function of preventing damage by a medium mask and a magnetic head. Examples of the lubricant used for the lubricating layer include a fluorine-based lubricant, a hydrocarbon-based lubricant, a mixture thereof, and the like. The lubricating layer is preferably thinner so as not to hinder the formation of the magnetic pattern. It is preferably 10 nm or less. In order to obtain sufficient lubrication performance, the thickness is preferably 1 nm or more. However, when irradiating the energy beam from above the lubricating layer, re-application may be performed in consideration of damage (decomposition, polymerization) of the lubricant.

The method of forming a control magnetization pattern according to the present invention may be performed before or after forming the lubricating layer. Furthermore,
In order not to impair the running stability of the flying / contact head,
After forming the control magnetization pattern, the surface roughness Ra of the medium is set to 3
It is preferable to keep it at or below nm. The medium surface roughness Ra
Is the roughness of the medium surface not containing the lubricating layer.
This is a value calculated according to B0601. More preferably, the thickness is 1.5 nm or less.

More preferably, the surface waviness Wa of the medium after forming the control magnetization pattern is kept at 5 nm or less. Wa
Is the waviness of the medium surface not containing the lubricating layer, and is a value calculated according to Ra calculation after measuring with a measuring length of 2 mm using a stylus type surface roughness meter. More preferably, the thickness is 3 nm or less. The formation of the control magnetization pattern on the magnetic recording medium is performed on the recording layer. After forming the protective layer, or the protective layer and the lubricating layer on the recording layer, it is preferably performed by any of the conventional methods, but if there is no concern about oxidation of the recording layer, it is performed immediately after the formation of the recording layer. Is also good.

Various methods can be adopted as a film forming method for forming each layer of the magnetic recording medium. An evaporation method is mentioned. As the conditions at the time of film formation, the ultimate vacuum, the substrate heating method and substrate temperature, the sputtering gas pressure, the bias voltage, and the like are appropriately determined according to the characteristics of the medium to be obtained. For example, in the case of sputtering film formation, the ultimate vacuum degree is usually 5 × 10 ⁻⁶ Torr.
Hereinafter, the substrate temperature is preferably from room temperature to 400 ° C., the sputtering gas pressure is preferably from 1 × 10 ^{−3 to} 20 × 10 ⁻³ Torr, and the bias voltage is preferably from 0 to −500 V.

In the case of heating the non-magnetic substrate, the film may be formed 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. If the recording layer is a rare-earth magnetic film, the innermost and outermost parts of the disc are first masked, the film is formed up to the recording layer, and then the protective layer is formed from the viewpoint of preventing corrosion and oxidation. In this case, the mask is removed and the recording layer is completely covered with the protective layer.
The film is formed while masking the recording layer and the first protective layer.
It is preferable to remove the mask when the protective layer is formed and completely cover the recording layer with the second protective layer, because corrosion and oxidation of the rare earth magnetic layer can be prevented.

The magnetic recording apparatus of the present invention includes at least one of the above-described magnetic recording media, a driving unit for driving the magnetic recording medium in a recording direction, a magnetic head including a recording unit and a reproducing unit,
The magnetic recording apparatus includes means for moving a magnetic head relative to a magnetic recording medium, and means for processing a signal for inputting a signal to the magnetic head and reproducing a signal output from the magnetic head.

Further, after assembling the magnetic recording medium into the device, the magnetic pattern is reproduced by a magnetic head to obtain a signal, and a servo burst signal is recorded by the magnetic head with reference to the signal. Even if it is used, a precise servo signal can be easily obtained. Also, 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. Is easily returned to a desired position, and therefore, a magnetic recording apparatus in which signals by both writing methods are present has high reliability.

A description will be given of a typical magnetic disk device as a magnetic recording device. A 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 bearings, and a magnetic disk used for recording and / or reproduction. A head, an arm to which the head is attached, and an actuator capable of moving the head to an arbitrary position on the magnetic recording medium via the head arm. It is moving at a flying height. The recording information is converted into a recording signal via a signal processing means and recorded by a magnetic head. Further, the reproduction signal read by the magnetic head is inversely converted through the signal processing means to obtain reproduction information.

On the disk, 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, the servo pattern for generating the 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 frequently used at present consists 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 の 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 limited to about 0.2 to 0.3 μm due to the influence of vibration caused by the difference in the center of gravity between the external pin and the actuator. However, it is becoming difficult to improve the recording density and reduce the cost of the magnetic recording apparatus.

According to the present invention, it is possible to efficiently form a highly accurate magnetization pattern by using a reduced image forming technique. A servo pattern can be formed well, and the track density of the medium can be increased to, for example, 40 kTPI or more. Therefore, a magnetic recording device using this medium can perform high-density recording.

Further, when the phase servo system 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 is possible, so that higher density recording is possible. is there. As described above, in the phase servo method, for example, from the inner circumference to the outer circumference,
A magnetization pattern that extends linearly obliquely to the radius is used. Such a continuous pattern or an oblique 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 a complicated calculation and configuration are required.

However, according to the present invention, once a mask corresponding to the shape is once formed, the pattern can be easily formed only by reducing and forming an energy beam passing through the mask at a desired position on the disk. In addition, 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. Particularly, since the beam is narrowed down, it is suitable for a magnetic recording medium having a small diameter and a high recording density, and is preferably applied to a magnetic disk having a diameter of 65 mm or less. More preferably, it is 2 inches or less, and still more preferably, 1 inch or less. 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 through holes in either the front or rear surface of the drive, and the magnetic head is moved mechanically to record one pattern at a time along the track.
For this reason, it takes a very long time of about 15 to 20 minutes per drive. These operations have to be performed in a clean room because a dedicated servo writer is used and holes are formed in the drive, which is complicated in the process and increases 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. Can be formed. The magnetic recording device incorporating the medium on which the servo pattern is formed as described above does not require the servo pattern writing step.

Alternatively, a magnetic recording apparatus incorporating a medium on which a servo pattern recording reference pattern is formed can write a desired servo pattern 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.

Furthermore, in the present invention, since there is a gap corresponding to the focal length between the imaging means and the medium, damage due to contact between the magnetic recording medium and other constituent members, minute dust or dust Can be prevented from damaging the medium due to pinching of the medium, and the occurrence of defects can be prevented. As described above, according to the present invention, a magnetic recording device capable of high-density recording can be obtained in a simple process at low cost. Various magnetic heads 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 an MR head, a 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, this magnetic head has a flying height of 0.00.
When flying at a height of 1 μm or more and less than 0.05 μm, which is lower than the conventional height, the output is improved and a high device S / N is obtained, so that a large-capacity and highly reliable 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, when recording / reproducing at a recording density of 13 kTPI or more, a linear recording density of 250 kFCI or more, and a recording density of 3 Gbits or more per square inch, Also obtains a sufficient S / N.

Further, the reproducing portion of the magnetic head is disposed between a plurality of conductive magnetic layers which cause 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.

[0123]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The magnetic recording medium of the present invention will be described in detail below, but is not limited by the embodiments unless it goes beyond the gist of the invention. Example 1 A 2.5-inch-diameter aluminosilicate glass substrate was washed and dried, and a degree of vacuum reached thereon was 1 × 10 ⁻⁷ Torr.
r, substrate temperature: 350 ° C., bias voltage: −200 V,
Sputtering gas pressure: Ar 3 × 10 ⁻³ Torr, NiAl 60 nm, Cr ₉₄ Mo _{6 10} n
m, 22 nm of Co ₇₂ Cr ₁₈ Pt ₁₀ as a recording layer, and 5 carbon (diamond-like carbon) as a protective layer.
nm was formed by sputtering. Surface roughness Ra is 0.5n
m and undulation Wa were 0.8 nm. On top of this, a fluorine-based lubricant was applied to a thickness of 1.5 nm as a lubricant layer,
Baking at 100 ° C for 40 minutes, coercive force 3000O at room temperature
e, a magnetic disk for in-plane recording having a saturation magnetization of 310 emu / cc was obtained. The Curie temperature of the recording layer was 250 ° C.

On the obtained magnetic disk, a magnetization pattern was formed as follows. The magnetic disk was mounted on the magnetization pattern forming apparatus shown in FIG. 1, and was uniformly magnetized in the circumferential direction of the disk by applying an external magnetic field of 10 kOe. Thereafter, the external magnetic field applying means was replaced to obtain the device configuration as shown in FIG. 2, and an excimer pulse laser was irradiated using the optical system shown in FIG. 4 to form a magnetization pattern. The pulse laser irradiation optical system uses an excimer pulse laser light source having a wavelength of 248 nm as an energy ray source and a pulse width of 25 ns.
c, A pulse laser having a beam diameter of 10 mm * 30 mm (a diameter that is 1 / e ^{2 of the} peak energy) was emitted. One pulse was taken out from among them with a programmable shutter, and the intensity was adjusted with an attenuator so that the power on the magnetic disk was about 80 mJ / cm ² . Next, the diameter 5
Using a condenser lens composed of a combination of a 0 mm aspherical lens and a plano-convex lens, the light was condensed so that the intensity distribution in the beam on the mask surface was uniform and passed through the mask to obtain a patterned energy ray. FIG. 6 shows a schematic diagram of the mask used. (A) is an overall view, and (b) is an enlarged view of a mask region. The mask is made of quartz glass as a base material, and is formed with irregularities depending on the presence or absence of a Cr layer having a thickness of about 20 nm (the convex portions are non-transmissive, and the concave portions are transmissive portions). The mask has an inner diameter of 20 mm (radius 10 mm) and an outer diameter of 130 mm (radius 6).
5 mm), a radius of 40 mm to 50 mm, and an angle θ =
The transmission part is patterned in a range of 5 degrees. (B)
Shows an enlarged view. There are formed 300 transmission portions each formed of a long straight line of 10 mm in the radial direction. The minimum width in the circumferential direction of each of the transmitting portion and the non-transmitting portion is 4 μm. The patterned energy ray was reduced and imaged on the medium surface by an imaging lens having a diameter of 20 mm arranged so that the focal position of the condenser lens was at the center. The reduction ratio was 1/4. That is, the pattern on the mask was formed on the disk with the length and width reduced to 1/4. About 1.5kGau at the same time
A magnetic field of ss was applied by a permanent magnet in the direction opposite to the initial circumferential magnetization. The evaluation of the formed magnetic pattern was performed by developing the magnetic pattern with a magnetic developer and observing it with an optical microscope. As a result, it was found that 300 magnetization patterns having a width of 1 μm were formed. Next, the presence or absence of damage to the protective layer due to laser irradiation was confirmed by measuring the peaks of graphite and diamond by Raman spectroscopy. If the protective layer is damaged by the laser, the peak intensity of diamond decreases after laser irradiation and the peak intensity of graphite increases, but in this example, the peak ratio before and after irradiation did not change. With respect to the damage (decomposition, polymerization) of the lubricant and the like, the presence or absence of damage was confirmed by measuring the number average molecular weight and the weight average molecular weight before and after the laser irradiation, but no difference was observed before and after the irradiation. If the method of this embodiment is applied to the formation of a servo pattern on a magnetic disk, a magnetic disk having a highly accurate servo pattern can be obtained simply and in a short time. Furthermore, the magnetic disk device using this magnetic disk does not need to newly record a servo pattern, can perform tracking with high accuracy, and can perform high-density recording. Example 2 After manufacturing a magnetic disk in the same manner as in Example 1, a magnetization pattern was formed as described below. The magnetic disk was mounted on the magnetization pattern forming apparatus shown in FIG. 1, and was uniformly magnetized in the circumferential direction of the disk by applying an external magnetic field of 10 kOe.
Thereafter, the external magnetic field applying means was replaced to form the device configuration as shown in FIG. 2, and an excimer pulse laser was irradiated using the optical system shown in FIG. 5 to form a magnetization pattern. The pulse laser irradiation optical system has a wavelength of 26 as an energy ray source.
Using a 6 nm YAG fourth harmonic Q-switched laser light source,
A pulse width: 5 nsec and a beam diameter: 8 mm in diameter (a diameter that is 1 / e ^{2 of the} peak energy) were emitted. Take one pulse out of it with a programmable shutter,
After adjusting the intensity with an attenuator so that the power on the magnetic disk became about 50 mJ / cm ² , the beam diameter was increased to 24 mm with a triple beam expander. Next, a condensing lens composed of a combination of an aspherical lens having a diameter of 50 mm and a plano-convex lens was condensed so that the intensity distribution in the beam on the mask surface was uniform and passed through the mask to obtain a patterned energy ray. . The mask used is almost the same as that shown in FIG.
The transmission part is patterned in a range of 48 mm from the angle θ = 15 degrees. In other words, 800 transparent portions formed of a long straight line of 8 mm in the radial direction are formed. The minimum width in the circumferential direction of each of the transmitting portion and the non-transmitting portion is 4 μm.
The patterned energy ray was reduced and imaged on the medium surface by an imaging lens having a diameter of 20 mm arranged so that the focal position of the condenser lens was at the center. Reduction rate is 1 /
And 4. That is, the length and width of the pattern on the mask are 1 /
4 and an image was formed on the disk. About 1.5k at the same time
A Gaussian magnetic field was applied by a permanent magnet in a direction opposite to the initial circumferential magnetization. The evaluation of the formed magnetic pattern was performed by developing the magnetic pattern with a magnetic developer and observing it with an optical microscope. As a result, it was found that 800 magnetization patterns having a width of 1 μm were formed.
Also, as in Example 1, the presence or absence of damage due to laser irradiation of the protective layer and the lubricant was confirmed, but no difference was observed before and after the irradiation. If the method of this embodiment is applied to the formation of a servo pattern on a magnetic disk, a magnetic disk having a highly accurate servo pattern can be obtained simply and in a short time. Furthermore, the magnetic disk device using this magnetic disk does not need to newly record a servo pattern, can perform tracking with high accuracy, and can perform high-density recording.

[0125]

As described above, according to the present invention,
In a technology for forming a magnetic pattern on a magnetic recording medium by combining local heating and application of an external magnetic field, a magnetic pattern forming method and a magnetic pattern forming apparatus for forming a fine magnetic pattern efficiently and more accurately are provided, and as a result, a higher density A recordable magnetic recording medium and a magnetic recording device can be provided in a short time and at low cost.

[Brief description of the drawings]

FIG. 1A is a schematic cross-sectional view of an example of a disk holding unit and a magnetic field applying unit of a magnetization pattern forming apparatus according to the present invention. (B) is a schematic diagram of an example of a disk holding unit and a magnetic field applying unit of the magnetization pattern forming device of the present invention.

FIG. 2 is a schematic sectional view of an example of a disk holding unit and a magnetic field applying unit of the magnetic pattern forming apparatus according to the present invention.

FIG. 3 is an explanatory diagram of an example of the energy beam irradiation optical system of the present invention.

FIG. 4 is an explanatory diagram of another example of the energy beam irradiation optical system of the present invention.

FIG. 5 is an explanatory diagram of an example of a light shielding plate of the present invention.

FIG. 6 is an explanatory diagram of a mask used in the example of the present invention.

[Explanation of symbols]

 Reference Signs List 1 magnetic disk 2 spindle 3 turntable 3 4 first magnetic field applying means 5 yoke 6, 6a, 6b permanent magnet 7 vacuum groove 8 second magnetic field applying means 9 yoke 10 permanent magnet 11 pulse laser 12 photomask 13 transparent substrate 14 opaque layer Reference Signs List 15 imaging lens 21 hard substrate 22a, 22b magnetic thin film 41 pulse laser light source 42 programmable shutter 43 attenuator 44 condenser lens 44a aspherical lens 44b plano-convex lens 45 beam expander 46 light shielding plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D006 AA02 AA05 AA06 BB07 DA03 EA00 FA00 5D042 LA01 MA02 5D112 AA24 DD00 GA19

Claims (21)

[Claims] 1. A method for forming a magnetic pattern on a magnetic recording medium having a magnetic thin film on a substrate by locally heating the magnetic thin film and applying an external magnetic field to the magnetic thin film. When the magnetic thin film is locally heated by irradiating the medium surface with an energy beam, a patterned energy beam having an intensity distribution according to a magnetization pattern to be formed is reduced and imaged on the medium surface. Of forming a magnetic pattern of a magnetic recording medium. 2. The magnetic recording medium according to claim 1, wherein the intensity distribution of the energy beam is changed according to a magnetization pattern to be formed, and the energy beam is converted into a patterned energy beam. A method for forming a magnetic pattern on a recording medium. 3. The method according to claim 2, wherein the intensity distribution of the energy beam is changed by passing the energy beam through a mask having a transmission part that partially transmits the energy beam. 4. The method according to claim 1, wherein the minimum width of the magnetic pattern is 2 μm or less. 5. The magnetic pattern of a magnetic recording medium according to claim 1, wherein the magnetic pattern includes a servo pattern for controlling the position of a recording / reproducing head or a reference pattern for recording a servo pattern. Forming method. 6. The method according to claim 1, wherein the magnetic recording medium is a magnetic disk having a diameter of 65 mm or less. 7. An external magnetic field is applied to uniformly magnetize the magnetic thin film in a desired direction in advance. Then, the magnetic thin film is locally heated, and at the same time, an external magnetic field is applied to cause the heating portion to move in a direction opposite to the desired direction. The method for forming a magnetic pattern of a magnetic recording medium according to claim 1, wherein the magnetic pattern is formed by magnetizing. 8. The method according to claim 1, wherein the energy beam is a pulse laser emitted from a pulse laser light source. 9. The temperature at which the magnetization of the magnetic thin film disappears is 10.
9. The method for forming a magnetic pattern of a magnetic recording medium according to claim 1, wherein the temperature is 0 ° C. or higher. 10. The method according to claim 1, wherein the magnetic recording medium has a magnetic thin film and a protective layer on a substrate in order. 11. The method according to claim 10, wherein the thickness of the protective layer is 50 nm or less. 12. The method according to claim 10, wherein the protective layer is made of diamond-like carbon. 13. The method according to claim 10, wherein the magnetic recording medium has a lubricating layer on the protective layer. 14. A magnetic recording medium having a surface roughness Ra of 3 nm.
The method for forming a magnetic pattern of a magnetic recording medium according to claim 1, wherein: 15. A magnetic recording medium, wherein a magnetic pattern is formed by the method of forming a magnetic pattern according to claim 1. Description: 16. A magnetic recording medium, a driving unit for driving the magnetic recording medium in a recording direction, a magnetic head including a recording unit and a reproducing unit, means for moving the magnetic head relative to the magnetic recording medium, A magnetic recording apparatus having recording / reproducing signal processing means for inputting a recording signal to a head and outputting a reproduction signal from a magnetic head, wherein the magnetic recording medium is the magnetic recording medium according to claim 15. Magnetic recording device. 17. After assembling the magnetic recording medium into the device,
The magnetization pattern is reproduced by a magnetic head to obtain a signal,
17. The magnetic recording apparatus according to claim 16, wherein a servo burst signal is recorded by the magnetic head based on the signal. 18. A method in which a magnetic recording medium having a magnetic thin film on a substrate is irradiated with energy rays to locally heat the magnetic thin film and a step of applying an external magnetic field to the magnetic thin film to form a magnetization pattern. An apparatus for forming, comprising: a medium holding unit for holding a magnetic recording medium; an external magnetic field applying unit for applying an external magnetic field to the magnetic recording medium; an energy ray source for emitting an energy ray; A mask means for changing the intensity distribution of the energy ray according to the magnetization pattern to be formed; and a mask means arranged between the mask means and the magnetic recording medium, and the energy ray having the changed intensity distribution is reduced and imaged on the medium surface. A magnetic pattern forming apparatus, comprising: an imaging unit. 19. The magnetic pattern forming apparatus according to claim 18, wherein the mask means is a mask having a transmission part that partially transmits the energy beam. 20. The magnetization pattern forming apparatus according to claim 18, wherein the energy ray source is a pulse laser light source. 21. The magnetic pattern forming apparatus according to claim 18, further comprising a condenser lens between the energy ray source and the mask means.