KR100931763B1 - magnetic pattern forming device - Google Patents

Abstract

A method of forming a magnetic pattern on a magnetic recording medium sequentially formed of a magnetic layer, a protective layer, and a lubricant layer on a substrate, the method comprising locally heating the magnetic layer and applying an external magnetic field to the magnetic field. Applying to the layer. This method can form a high density magnetic pattern in a magnetic recording medium accurately and in the simplest way in a short time. In addition, a magnetic recording apparatus and a magnetic recording medium capable of recording information at high density can be provided in an economical manner in a short time.

Description

Magnetic Pattern Forming Device {MAGNETIC PATTERN FORMING DEVICE}

The present invention relates to a method, a magnetic recording medium or a magnetic recording apparatus for forming a magnetic pattern on a magnetic recording medium used in a magnetic recording apparatus. In particular, the present invention relates to a method, a magnetic recording medium or a magnetic recording apparatus for forming a magnetic pattern on a magnetic recording medium, wherein the magnetic recording medium has a magnetic layer, a protective layer and a lubricating layer and is flying / contacting. Type magnetic head is used for recording or playback.

Magnetic recording devices represented by magnetic disk devices (hard disk drives) have been widely used as external memory devices for information processing devices such as computers, and have recently been used as recording devices for devices for recording set top boxes or moving pictures. Has been.

Conventional magnetic disk devices include a motor, information for rotating a magnetic disk or disks connected to the shaft by inserting a shaft, bearing or bearings for supporting a single or multiple magnetic disks through the center of the magnetic disk or disks. A magnetic head for recording / reproducing, an arm for supporting the magnetic head, and a driving device for moving the magnetic head through the arm to a desired position on the magnetic recording medium. As the recording / reproducing head, a flying type magnetic head capable of moving on a magnetic recording medium at a constant flying height is commonly used.

In addition to the flying magnetic head, a contact magnetic head has been proposed to bring the distance to the medium closer.

In general, a magnetic recording medium disposed in a magnetic disk device forms a NiP layer on the surface of a substrate including an aluminum alloy, and is subjected to a smoothing, texturing, and the like, followed by a lower metal layer and a magnetic layer thereon. (Information recording layer), a protective layer, a lubricating layer, etc., are formed in order. Alternatively, this is produced by forming a lower metal layer, 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 horizontal magnetic recording media and vertical magnetic recording media. In the horizontal magnetic recording medium, horizontal recording is generally performed.

The speed of increasing the density of the magnetic recording medium further increases every year, and various techniques for increasing the density have been proposed. For example, attempts to lower the flying height of the magnetic head, attempt to use the GMR head as the magnetic head, improve the magnetic material used in the recording layer of the magnetic disk to have a strong coercive force, and There are attempts to record information, to reduce the space between tracks. For example, to realize 100 Gbit / inch ² , a track density of 100 ktpi or more is required.

In each track, a magnetic pattern for controlling the magnetic head is formed. For example, this generates signals used to control the position of the magnetic head or signals used for synchronous control. In the case where the space between adjacent information recording tracks is narrowed to increase the number of tracks, signals for controlling the position of the data-recording / playhead in the radial direction of the disc in response to the increased number of tracks (hereinafter It is necessary to generate more of the signals to densify, so-called " servo signal "

Further, by reducing the area used for recording data, i.e., the gap areas between the servo areas and the data recording areas and the surface area other than the area used for the servo signals, the data to increase the data recording capacity is increased. The demand for widening the recording area is increased. To this end, it is necessary to steam the output of the servo signals or increase the precision of the synchronization signals.

In a conventional method widely used for manufacturing, an opening is formed in the vicinity of a head drive of a drive (magnetic recording device), and a pin with an encoder is inserted into the opening so that the pin and the drive engage with each other, so that the correct position is achieved. Servo signals were recorded by moving the head. However, since the position of the center of gravity of the drive was different from the position of the center of gravity of the positioning mechanism, such a method has difficulty in accurately recording servo signals, so that very accurate track position control could not be obtained.

On the other hand, laser beams are irradiated onto the magnetic disk to locally change the surface of the magnetic disk, so that fine protrusions and recesses are physically formed and servo signals are generated by the fine protrusions and recesses. Proposals exist. However, in this technique, the formed protrusions and recesses destabilize the flying magnetic head, adversely affecting the recording or reproduction of information; Such problems exist because laser beams require large power to form protrusions and recesses and are expensive and take a long time to form protrusions and recesses one by one.

In view of the above, several servo signal forming methods have been proposed.

For example, a servo pattern is formed on a master disk having a high coercive magnetic layer, the master disk is in close contact with a magnetic recording medium, and then an auxiliary magnetic field is applied to the magnetic recording medium from the outside so that the magnetic pattern is printed. There is a method (USP 5,991,104).

As another example, the medium is pre-magnetized along an arbitrary direction, a ferromagnetic layer having a soft magnetic layer is formed by patterning on the master disc, the master disc being in close contact with the medium, after which an external magnetic field There is a way in which is applied. The soft magnetic layer functions as a shield, and the magnetic pattern is printed in the unshielded area [JP-A-50-60212 (USP 3,869,711), JP-A-10-40544 (EP915456), and Digest of InterMag 2000, GT-06].

With regard to the formation of the shield or the use of a magnetic recording source, the techniques described above use a master disc, and a magnetic pattern is formed in the medium by applying a strong magnetic field.

The strength of the magnetic field typically depends on the distance. When a magnetic pattern is recorded by applying a magnetic field, the transition of the magnetic pattern tends to be obscured by the leakage magnetic field. Therefore, it is essential to bring the master disk into close contact with the medium in order to minimize the effects of its leakage magnetic field. As the magnetic patterns become finer, it is necessary to bring them in close contact without any gaps. Typically, both members are press-contacted by using a vacuum inhaler.

Also, the larger the coercive force of the medium, the larger the magnetic field used for transfer, and therefore the larger the leakage magnetic field. Thus, complete hermetic contact is required.

The above-described techniques are applicable to magnetic disks having low coercive force or to flexible floppy disks which are easy to press contact. However, it is very difficult to apply these techniques to high density recording magnetic disks with a hard substrate, where the coercive force is more than 3,000 Oe.

That is, in a magnetic disk having a hard substrate, there was a possibility that fine dust accumulated on the substrate during airtight contact, causing defects in the medium or damaging an expensive master disk. In particular, in the case of glass substrates, there have been problems in that deposition of dust causes insufficient airtight contact, making it impossible to perform magnetic printing, or causing cracks in the magnetic recording medium.

In the technique described in JP-A-50-60212 (USP 3,869,711), there is such a problem that a pattern having an inclined angle in the direction of tracks in the disc is limited to a weak pattern in signal strength even if recording is possible. It was. In a magnetic recording medium having a high coercive force of 2,000 to 2,500 Oe or more, for a ferromagnetic material (for a shield material) for forming a pattern in a master disk, a soft magnetic material having a large saturation magnetic flux density such as senddust. Or a permalloy must be used to ensure sufficient magnetic field strength for printing.

However, in the case of the inclined pattern, the magnetic field formed by reversing the magnetization was oriented in a direction perpendicular to the gap generated by the ferromagnetic layer of the master disk, and it was impossible to incline the magnetization in the desired direction. As a result, part of the magnetic field escaped to the ferromagnetic layer, and sufficient magnetic field could not be applied to the desired position of magnetic printing, so that a sufficient pattern of opposite magnetization could not be obtained, and it was difficult to generate high intensity signals. The reduction in reproduction power by using the inclined magnetic pattern compared to the magnetic pattern perpendicular to the tracks is greater than the reduction due to azimuth loss.

It is an object of the present invention to provide a magnetic pattern forming method which can form various fine magnetic patterns effectively and accurately without damaging a mask or the medium and increasing the defects in the medium.

It is an object of the present invention to provide a magnetic recording apparatus and a magnetic recording medium which can be manufactured in a short time in an economical manner and capable of high density recording.

The inventors of this specification have extensively studied the above-mentioned problems, and by combining the steps of locally heating a magnetic layer and applying an external magnetic field to the magnetic layer, a magnetic pattern can be formed effectively and accurately on the magnetic recording medium. The present invention has been accomplished by discovering that it can.

According to a first aspect of the present invention, there is a method of forming a magnetic pattern in a magnetic recording medium having a magnetic layer, a protective layer, and a lubricating layer formed on a substrate in the following order, wherein the method locally forms the magnetic layer. Heating and applying an external magnetic field to the magnetic layer.

According to the second aspect of the present invention, there is provided a magnetic recording medium in which the magnetic pattern is formed by the magnetic pattern forming method described in the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a magnetic recording medium in which a magnetic pattern is formed by the magnetic pattern forming method described in the first characteristic, a driving means for driving the magnetic recording medium in the recording direction, a recording portion and a reproduction portion. A magnetic recording apparatus is provided that includes a head, means for moving the magnetic head relative to the magnetic recording medium, and recording / reproducing signal processing means for supplying a recording signal to the magnetic head and receiving a reproduction signal from the magnetic head.

According to a fourth aspect of the present invention, a magnetic recording medium having a magnetic layer on a substrate using a step of irradiating energy beams on the magnetic recording medium to locally heat the magnetic layer and to apply an external magnetic field to the magnetic layer. There is provided a magnetic pattern forming apparatus in which a magnetic pattern is formed, the magnetic pattern forming apparatus comprising a medium supporting means for supporting a magnetic recording medium, an external magnetic field applying means for applying an external magnetic field to the magnetic recording medium, and radiating energy beams. Energy beam source for irradiating energy beams radiated from the energy beam source to the magnetic recording medium, energy beam source and magnetic recording medium for changing the intensity distribution of the energy beams in response to the magnetic pattern to be formed It is characterized by including a mask located between.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a magnetic recording medium having a magnetic layer, a protective layer and a lubricating layer formed on a substrate in the following order, wherein a magnetic pattern is formed in the magnetic layer, The method includes forming a magnetic layer and a protective layer on a substrate, forming a lubricating layer on the protective layer, and forming a magnetic pattern by locally heating the magnetic layer with application of an external magnetic field. It is characterized by.

According to the present invention, it is possible to provide a method for manufacturing a magnetic recording medium having high durability and high impact resistance, so that patterns can be effectively formed with high precision. Further, a magnetic recording apparatus and a magnetic recording medium capable of high density recording and high durability in a short period of time and at low cost can be provided.

The present invention is described in detail.

In the first aspect of the present invention, there is provided a magnetic layer, a protective layer, and a lubricating layer formed on a substrate in the following order, combining a step of locally heating a magnetic layer and applying an external magnetic field to the magnetic layer. Magnetic patterns are formed on the magnetic recording medium.

According to the invention, there is no need to use a strong external magnetic field as by conventional techniques since the local heating and the application of an external magnetic field are combined in forming the magnetic pattern. Also, even when a magnetic field is applied to a region other than the heating region, the region is not magnetized, so the patterning region can be limited to the heating region. Thus, the boundaries of the magnetic regions become clear, and the magnetic transition width is small; Magnetic transitions at the boundaries of magnetic regions are very rapid; A pattern of high quality of the output signals can be formed.

Furthermore, there is no need to press-contact the medium to the master disk as in the prior art. Thus, there is no risk of damaging the medium or mask or increasing defects in the medium.

In addition, forming a protective layer on the magnetic layer prevents damage to the magnetic layer due to the collision of the magnetic head. Formation of a lubrication layer provides lubrication properties between the magnetic head and the medium so that a fly / contact magnetic head can be used. The surface of the disc before the formation of the magnetic pattern has defects such as protrusions, dust, and the like, and when energy beams are irradiated onto the surface, irregular reflections cause disorder of the magnetic pattern to be formed around or in the area. Therefore, in the present invention, it is important to use a medium without defects. Therefore, it is desirable to inspect the defects with a magnetic head before the formation of the pattern in order to remove the defective media in advance. In order to inspect with a magnetic head, a lubricating layer must be previously formed on the medium. Therefore, in the present invention, the lubrication layer is most useful in manufacturing, so the lubrication layer must be formed before forming the magnetic pattern. Additionally, the method of the present invention can control the surface roughness of the medium to be small since non-uniform surfaces in the medium and damage of the medium can not occur or the increase in defects in the medium can be minimized. The operations of the magnetic head in contact with or floating on the medium can be stabilized. Thus, the distance between the magnetic layer and the head can be reduced by using the flying / contacting head, so that high density information recording can be performed in comparison with the magneto-optical disk or the optical disk using another type of magnetic head. have.

In order not to adversely affect the formation of the magnetic pattern, the lubricating layer is preferably thin and 10 nm or less. However, the thickness of the layer is preferably 0.5 nm or more in order to obtain sufficient lubrication performance.

The protective layer prevents damage to the magnetic layer due to intrusion of dust or collision of the head between the magnetic layer and the mask. In the present invention, the protective layer is essential in that it prevents oxidation of the heated magnetic layer. The magnetic layer is typically oxidative. When the magnetic layer is heated, it is easily oxidized. In the present invention, since the magnetic layer is locally heated by the energy beams, it is necessary to form a protective layer as anti-oxidation member on the magnetic layer in advance.

If the protective layer is too thick, thermal protection in the lateral direction may occur and the magnetic transition region of the magnetic pattern may be blunted, so the protective layer is preferably thin. In addition, in the magnetic recording medium, it is necessary to make the hard type protective layer thin so that the distance between the head and the magnetic layer approaches the limit. Therefore, the thickness is preferably 50 nm or less. However, the thickness is preferably 0.1 nm or more in order to obtain sufficient durability.

In view of lubricating properties and impact resistance, it is preferable that a carbon material is used for the protective layer. In particular, diamond-based carbon is preferred because such a material should function to prevent damage to the magnetic layer by application of energy beams and be very resistant to damage to the magnetic layer by collision of the head. The magnetic pattern forming method of the present invention can be applied to an opaque protective layer such as a carbon protective layer.

According to the invention, a non-uniform surface is not produced on the medium and the master disc does not contact the medium. Therefore, the surface roughness of the medium after the formation of the magnetic pattern can be maintained at the same level as the surface roughness before the formation of the magnetic pattern, and there is no risk of unstable operation of the flying / contacting head. The surface roughness Ra is preferably 3 nm or less. In this specification, the surface roughness Ra of the medium means the roughness of the surface of the medium not including a lubricating layer, and is a value obtained by measuring a measurement length of 400 μm using a contact finger type surface roughness meter. And the obtained value is calculated by JIS B0601.

Preferably, the present invention can be applied to information of a magnetic pattern having information for controlling the recording / reproducing means. Information for control controls recording / reproducing means such as a magnetic head. For example, the information for control includes servo information for determining the position of the magnetic head on the data track, address information showing the position of the magnetic head on the medium, and synchronization information for controlling the recording / reproducing speed of the magnetic head, and the like. do. The information for control also includes reference information based on the fact that the servo information is recorded later.

Magnetic patterns for control should be formed with high precision. In particular, the servo pattern is a pattern for controlling the position of data tracks. If the precision of the servo pattern is poor, the position control for the head becomes coarse, and a data pattern of higher precision than the servo pattern cannot be logically recorded. Therefore, as the recording density of the medium increases, the servo pattern must be formed with high precision. Therefore, as the recording density of the medium becomes higher, the servo pattern must be formed very precisely.

In the present invention, since a very precise servo pattern or reference pattern can be obtained, the present invention provides a remarkable effect especially when applied to a magnetic recording medium of high density recording such as a medium having a track density of 40 kTPI or more.

In addition, since a magnetic pattern extending obliquely with respect to the tracks can be preferably formed, this is particularly suitable for the inclination pattern for phase servo signals.

The invention is advantageous in that the servo pattern can be recorded on the area where the head is movable without using the magnetic head. Therefore, even when the head is outside the data recording area, the detectable range of the servo pattern is widened, so that the head can be easily returned.

Also, according to the present invention, it has been found that fine magnetic patterns having a minimum width of 2 μm or less can be formed precisely.

When energy beams are irradiated onto the medium through a gap formed between the medium and the mask, when the energy beams are diffracted by the mask to obscure the external structure of the pattern, it is necessary to precisely form the pattern to a size of about μm. It has been thought to be difficult.

In the present invention, however, the entire energy beam irradiation region is not magnetized by an external magnetic field, but only the region heated above the magnetization erasing temperature in the irradiation region is magnetized. That is, when the heating temperature does not exceed the threshold value, there is no influence of the external magnetic field, and the opacity of the pattern generated by the diffracted light can be significantly reduced, so that a fine pattern on the order of µm can be formed. There is no upper limit for forming the patterns, and a fine pattern may theoretically be formed in the limit range of the waveform of the energy beams. For example, using an excimer laser, a pattern of about 100 nm may be formed.

According to the method of the present invention, defects can be minimized and fine magnetic patterns can be easily formed in the magnetic disk in a short time while the surface roughness is kept small. Therefore, when the present invention is applied to a medium for recording / reproducing information using a flying / contacting magnetic head, the effect is high in practical use.

A technique in which light is irradiated onto a magneto-optical recording medium through a mask to form magnetic regions [for example, “High density magnetic holography using non-crystal thin TbFc film (1983, November), the 7th japan applied magnetism academy lecture summaries, 9pA-11 ”, JA-A-60-64376, JP-A-63-166050, JP-A-60-35336 (EP125535A)] have been proposed for quite some time to apply to the magneto-optical recording medium. The magneto-optical recording medium means a medium to be reproduced using the Kerr effect or the Faraday effect.

However, in the magneto-optical recording medium, protrusions and recesses for control information or guide grooves for tracking are formed in the substrate made of resin, so the proposed technique could not be executed. In the magneto-optical recording medium, since the distance between the recording layer and the optical head is about 1 mm, no problem occurs even if there are protrusions and recesses in the recording layer. Since a convenient and inexpensive injection mold can be used to form protrusions and recesses in a substrate made of resin, there is no need to form a magnetic pattern for control information.

On the other hand, recording and reproduction are performed on the magnetic recording medium using the flying magnetic head. Thus, a protective layer and a lubricating layer are provided to protect the magnetic layer, and have a unique structure in which protrusions and recesses in the substrate are not formable. In the present invention, a magnetic pattern can also be formed on such a magnetic recording medium by combining heat treatment and external magnetic field application treatment.

Next, a magnetic disk representing a magnetic recording medium will be described.

In the present invention, there are four methods which combine the steps of locally heating the magnetic layer and applying an external magnetic field to the magnetic layer.

Method 1: Prior to heating, a strong external magnetic field is applied to the magnetic layer to uniformly magnetize the magnetic layer in the desired direction, after which the desired region of the magnetic layer is at the magnetization erasing temperature, i.e., the Curie temperature Heated to the vicinity, a magnetic pattern is formed. In this method, the magnetic pattern can be formed in the easiest way. In addition, since the magnetic layer is uniformly magnetized, magnetic recording can be normally performed after the magnetic pattern is formed by this method.

Method 2: Prior to heating, a strong external magnetic field is applied to the magnetic layer to uniformly magnetize the magnetic layer in the desired direction, after which the desired area of the magnetic layer is heated to the magnetization erasing temperature, i.e., near the Curie temperature and weak at the same time. The magnetic field is applied to the region in a direction different from the direction of uniform magnetization, thereby canceling the magnetization, thereby forming a magnetic pattern. In this way, since a complete erase can be obtained, a magnetic pattern that can generate strong signals can be obtained.

Method 3: Heating and application of a weak external magnetic field are performed simultaneously, whereby only the region heated in the direction according to the external magnetic field is magnetized, thereby forming a magnetic pattern. In this method, a magnetic pattern can be formed in the easiest way. In addition, the external magnetic field to be used may be weak.

Method 4: Prior to heating, a strong external magnetic field is applied to the magnetic layer to uniformly magnetize the magnetic layer in the desired direction, after which the desired area of the magnetic layer is heated and at the same time the weak magnetic field is opposite to the direction before heating. Is applied to the area in the direction and magnetizes the area to form a magnetic pattern. In this way, a magnetic pattern capable of producing the strongest signals and excellent C / N and S / N can be obtained.

First, Method 1 is described in more detail.

A strong external magnetic field is applied to the magnetic disk to uniformly magnetize the magnetic layer completely in the desired magnetization direction. The means for applying an external magnetic field can be a magnetic head. Alternatively, multiple electromagnets or permanent magnets can be arranged such that magnetic fields are created in the desired magnetization directions. In addition, other means can be combined with such a member.

In the case of using a medium in which the easily magnetizable axis extends in the horizontal direction, the desired magnetization direction means the same or opposite direction as the moving direction of the data recording / reproducing head (the direction of relative movement between the medium and the head). . Further, in the case of using a medium in which the easily magnetizable axis extends perpendicularly to the horizontal direction, the desired magnetization direction means a vertical direction (upward or downward direction). Thus, in order to magnetize the magnetic layer in the desired magnetization direction between those described above, an external magnetic field is applied.

Uniform magnetization of the entire magnetic layer in the desired direction means that the entire magnetic layer is magnetized in substantially the same direction. However, in a strict sense, it is not necessary to magnetize the whole of the magnetic layer, but only the region where the magnetic pattern is formed should be magnetized in the same direction.

The strength of the magnetic layer varies depending on the characteristics of the magnetic layer of the magnetic recording medium. The magnetic layer is preferably magnetized by a magnetic field having a coercivity of about twice the coercivity of the magnetic layer at room temperature. When the strength of the magnetic field is weaker than that value, the magnetization may become insufficient. However, it should be magnetized to a coercive force of about 5 times or less than the coercive force of the magnetic layer at room temperature.

The surface of the magnetic layer of the magnetic disk is partially heated to the magnetization erasing temperature of the magnetic layer, i.e., near the Curie temperature, and the magnetism is erased. In this case, a situation may arise in which the magnetized region cannot be completely erased, and the magnetic layer is weakly magnetized than the magnetized region uniformly in the desired magnetization direction.

In method 2, the direction and intensity of the external magnetic field before heating are the same as those of method 1. The direction of the magnetic field applied simultaneously with the heating is in the horizontal direction in the case of a medium in which the easily magnetizable axis extends in the horizontal direction, or in the horizontal direction of the medium in the case in which the easily magnetizable axis extends perpendicular to the horizontal direction. In the vertical direction. Magnetization can be erased by applying such a magnetic field.

In addition, the strength of the magnetic field changes depending on the characteristics of the magnetic layer of the magnetic recording medium. The greater the intensity of the magnetic field, the easier the magnetic pattern is formed. However, the intensity of the magnetic field applicable should be less than the coercive force of the magnetic layer at room temperature. It is preferable to apply a magnetic field having a coercive force of 1/8 or more of the coercive force of the magnetic layer at room temperature. If the coercive force is lower than that value, the heated region can be magnetized again in the same direction as the circumferential region by the influence of the magnetic regions of the circumferential region at the cooling time.

However, the applicable magnetic field is preferably at most 2/3 times the coercivity of the magnetic layer at room temperature. When the coercive force has a higher value, magnetic regions in the circumferential region of the heated region can be affected. In particular, it is no more than 1/2 the coercive force of the magnetic layer at room temperature.

It must be heated to such a extent that the coercive force of the magnetic layer is reduced. For example, the temperature for heating is a temperature near the magnetization elimination temperature or the Curie temperature. It is preferable that heating temperature is 100 degreeC or more. Magnetic layers that easily withstand the influence of external magnetic fields below 100 ° C. exhibit low stability magnetic regions at room temperature. Moreover, as for heating temperature, 700 degrees C or less is preferable. When the heating temperature exceeds that temperature, there is a possibility that the magnetic layer is deformed.

In the method 3, the direction of the external magnetic field applied simultaneously with heating changes depending on the type of magnetic layer of the magnetic recording medium. When a medium in which the easily magnetizable axis extends in the horizontal direction is used, the external magnetic field is magnetized to be magnetized in the same or opposite direction as the direction in which the data recording / reproducing head is moved (the direction of relative movement of the medium and the magnetic head). Must be authorized to When a medium in which an easily magnetizable axis extends perpendicular to the horizontal direction is used, a magnetic field must be applied to the magnetic layer so that the magnetic layer is magnetized in the vertical direction (upward or downward direction).

The strength of the magnetic field is equal to the strength of the external magnetic field applied with heating in Method 2. In addition, heating temperature is the same as the temperature in the method 2.

In method 4, the direction and intensity of the external magnetic field applied before heating are the same as the direction and intensity in method 1.

Although the intensity of the magnetic field applied with heating is the same as that in Method 2, the direction of the magnetic field is opposite to the direction before heating, and the magnetic layer is locally magnetized in the opposite direction. The heating temperature is equal to the temperature in method 2.

According to the method 4, an external magnetic field is applied to the magnetic layer to uniformly magnetize the magnetic layer in a desired direction, and the magnetic layer is locally heated while an external magnetic field is applied to the magnetic layer in a direction opposite to the desired direction. By magnetizing the heated region, a magnetic pattern is preferably formed. According to this method, magnetic regions having a magnetic field direction in one direction and magnetic regions having an opposite direction can be formed clearly, and a magnetic pattern having strong signal strength and excellent C / N and S / N can be obtained. Can be.

Or in accordance with Method 1, a magnetic layer having a pattern having no magnetized area in the local area or a pattern having a weakly magnetized area in the local area in the desired direction is formed in the area magnetized uniformly in the desired direction, Magnetic recording media can be produced. Such a medium can be easily produced in a very short time by exposing the entire surface of the medium to the magnet uniformly at once and exposing it to light through a mask to cancel the magnetic field.

Next, a method of locally heating the magnetic layer of the present invention will be described.

The heating means preferably has a function of locally heating the surface of the magnetic layer. However, in view of the problem and controllability of heat diffusion into undesired parts, it is desirable to use energy beams such as lasers, since it is easy to control the size and power of the area to be heated.

In this case, it is preferable to use a mask because a plurality of magnetic patterns can be formed once by irradiating energy beams through the mask. This technique can reduce the time for the magnetic pattern forming step and is easy to use.

Also, to control the location and heating temperature of the heated region, it is desirable to form energy beams with pulsed energy beams rather than continuous irradiation.

In particular, it is preferable to use a pulsed laser light source. A pulsed laser source oscillates the laser intermittently in the state of a pulse. Compared to the case where the continuous laser is changed into a pulsed laser by optical devices such as an optical optical device (AO) and an electro-optical device (EO), a laser having a high peak value of power can be irradiated in a very short time. It is highly desirable to use a pulsed laser source, since heat storage is minimized.

In the case where the continuous laser is changed to a pulsed laser by such an optical device, the magnitude of the power in the pulse is substantially the same throughout the pulse width. On the other hand, in a pulsed laser source, for example, energy is stored by resonance in the pulsed laser source, and laser beams as pulses are radiated simultaneously. Thus, the power of the pulse is very large at the peak and then decreases. In the present invention, rapid heating and rapid cooling are preferable at the time of forming a magnetic pattern having high contrast and high precision, and therefore, it is preferable to use a pulsed laser source.

In order to increase the contrast ratio of the pattern or increase the recording density, the medium surface on which the magnetic pattern is formed must have a large temperature difference between the irradiation time of the pulse energy beams and the non-irradiation time. Thus, the substrate is preferably kept at room temperature or lower within the non-irradiation time of the pulsed energy beams. Room temperature is about 25 ° C. When the medium is locally heated by pulsed energy beams and at the same time an external magnetic field is applied, the external magnetic field can be applied continuously or in pulsed form in synchronization with the pulsed energy beams.

The wavelength of the energy beams is preferably 1,100 nm or less. When the wavelength is within such a range, since the diffraction effect is small and the resolution is increased, fine magnetic patterns are easily formed. In particular, the wavelength is 600 nm or less. Such wavelengths provide not only high resolution but also small diffraction, so that the space between the mask and the magnetic recording medium can be relatively widened, and therefore easy to operate and easy to assemble the magnetic pattern forming apparatus. In addition, the wavelength is preferably 150 nm or more. When the wavelength is smaller than 150 nm, the heat absorption by synthesizing the crystal used in the mask is large, so that it can be heated insufficiently. When the wavelength is 350 nm or more, optical glass can be used for the mask.

In particular, excimer lasers (248 nm) of YAG Q-switched lasers (1,064 nm), Ar lasers (488 nm, 5614 nm) or ruby lasers (694 nm); Second harmonic (532 nm), third harmonic (355 nm) or fourth harmonic (266 nm) may be used.

Although the power of the energy beams may be selected as an optimal value in consideration of the magnitude of the external magnetic field, the power of the pulsed energy beams per pulse is preferably 1,000 mJ / cm ² or less. Applying more power than the above-described value may damage the surface of the magnetic recording medium by the pulsed energy beams and cause deformation. When the surface roughness Ra is increased to 3 nm or more and the degree of undulation Wa is increased to 5 nm or more by deformation, a problem may arise in the movement of the fly / contact head.

Therefore, the power is preferably 500 mJ / cm ² or less, more preferably 100 mJ / cm ² or less. Within this range, a magnetic pattern with high resolution can be easily formed even when using a substrate having relatively large heat spreading characteristics. Moreover, as for electric power, 10 mJ / cm <^2> or more is preferable. When smaller than that value, the temperature rise in the magnetic layer is suppressed, and it is difficult to perform magnetic printing.

When the substrate used in the present invention is composed of a metal such as Al or an alloy thereof, the substrate has a large thermal conductivity. In this case, the power is in the range of 30 to 120 mJ / cm ² so that deformation of the magnetic pattern does not occur by thermal diffusion of the undesired area into the local area or physical damage of the substrate is caused by excessive energy. It is preferably present in.

When the substrate is made of a ceramic such as glass, the heat conduction is small compared to Al and the heat storage at the position where the pulsed energy beams are irradiated is large, so that the electric power is 10 to 100 mJ / cm ² . It is desirable to be in the range.

When the substrate is made of a resin such as polycarbonate, the heat storage at the location where the pulsed energy beams are irradiated is large, and the melting point is low compared to glass, so that the power is in the range of 10 to 80 mJ / cm ² . It is preferable to exist.

Also, when the damage to the magnetic layer, the protective layer or the lubrication layer by the energy beams is concerned, take the method of increasing the intensity of the applied magnetic field or applying pulsed energy beams at the same time when the power is small. Can be. For example, 25 to 75% of the coercive force of the greatest intensity possible at room temperature is applied to the medium of the horizontal recording type to reduce the energy of the energy beams. In the case of a horizontal recording type of medium, 1 to 50% of the coercive force of the greatest intensity possible at room temperature must be applied to slow down the energy.

When pulsed energy beams are irradiated to the magnetic layer through the protective layer and the lubricating layer, there is a case where the lubricating layer is coated again after irradiation in consideration of damage (decomposition, polymerization) of the lubricating layer.

이하인 것이 바람직하다. 펄스폭이 그 값보다 넓은 경우에, 상기 펄스화된 에너지빔들의 에너지에 의한 열이 자기 기록 매체로 분산되어, 해상도가 감소되기 쉽다. 1 펄스 당 전력이 같을 때, 펄스폭은 한 번에 강한 에너지를 발생하도록 짧게 되어야 하고, 이에 의해 열 분산이 작게 되고, 자기 패턴의 해상도는 증가되기 쉽다. 특히, 펄스폭은 100 nsec 이하이다. 그 범위내의 펄스폭을 사용하여, 비교적 큰 열 분산을 가지는 Al과 같은 금 속으로 만들어진 기판이 사용될 때에도, 높은 해상도를 가지는 자기 패턴을 형성하기 쉽다. 2 ㎛ 이하의 최소폭을 가지는 패턴을 형성시에, 펄스폭이 25 nsec 가 되도록 결정하는 것이 바람직하다. 즉, 크게 해상도를 고려하면, 펄스폭은 가능한한 짧아야 한다. 또한, 발생된 열이 자기층내의 자화의 전이가 완료될 때까지 유지될 수 있으므로, 펄스폭은 1 nsec 이상이 바람직하다.Pulse width of pulsed energy beams is 1

It is preferable that it is the following. When the pulse width is wider than that value, heat by energy of the pulsed energy beams is dispersed to the magnetic recording medium, so that the resolution is likely to be reduced. When the power per pulse is the same, the pulse width should be shortened to generate strong energy at one time, thereby making the heat dissipation small and the resolution of the magnetic pattern tend to be increased. In particular, the pulse width is 100 nsec or less. Using a pulse width within that range, it is easy to form a magnetic pattern having a high resolution even when a substrate made of metal such as Al having a relatively large heat dissipation is used. In forming a pattern having a minimum width of 2 m or less, it is preferable to determine that the pulse width is 25 nsec. That is, considering the resolution greatly, the pulse width should be as short as possible. Also, since the generated heat can be maintained until the transition of magnetization in the magnetic layer is completed, the pulse width is preferably 1 nsec or more.

As a kind of pulse-like laser, there is a laser capable of generating high frequency extreme pulses at the level of picoseconds or femtoseconds, such as modelocked lasers. In the period in which high frequency ultra-short pulses are applied, the laser is not irradiated within a very short time between each extreme pulse. However, since the non-irradiation time is very short, the portion to be heated is not substantially cooled. That is, the region once raised to a temperature above the Curie temperature may be maintained at a temperature higher than the Curie temperature.

Thus, in such a case, the continuous irradiation period (the continuous irradiation period between each extreme pulse includes the time for which the laser is not irradiated) is determined as one pulse. In addition, the total value of the irradiation energy amount in the continuous irradiation cycle is determined as the power per pulse (mJ / cm ^{2 )} .

Preferably, the intensity distribution of the energy beams in the energy irradiation area is within 15%, whereby the heat distribution in the irradiated area can be suppressed to be small, and the intensity distribution of the magnetization of the magnetic pattern can also be suppressed to be small. Thus, when the signal strength is read using the magnetic head, a magnetic pattern having a very uniform strength of the signal can be formed.

Energy beams, such as lasers, generally have an intensity distribution (density distribution of energy) within the beam spot. Even when the energy beams are irradiated to locally heat, a difference in temperature rise due to differences in energy density occurs. Thus, a difference in transfering intensity due to non-uniform heating occurs locally. When pulsed lasers such as excimer lasers or YAG-Q-switched lasers are used, the intensity distribution at the beam spot is generally within about 30%.

Thus, the intensity distribution of the energy beams at the beam spot is of small intensity distribution through a shading substrate or the like, for example by using an energy beam source having a small intensity distribution, whereby the transmissive portion can then be extended as needed. By passing only the energy portion with energy beams or by using a homogenizer or other optical elements, it should be suppressed to within 15%.

Preferably, the energy beams are equally processed in intensity distribution in advance, so that the heat distribution in the irradiated area can be suppressed to be small, and the distribution of the magnetic field intensity of the magnetic pattern can be suppressed to be small. Thus, when the signal strength is read out using the magnetic head, a magnetic pattern having a signal of very uniform intensity can be formed.

The intensity distribution equalization process may be a process of equalization using a homogenizer or other optical elements, or such a process of transmitting only a portion having a small intensity distribution of energy beams through a shading substrate or slit, the transmitted portion being necessary Can then be extended accordingly.

Preferably, the energy beams are equalized by optically dividing the energy beams into a plurality of parts and then superimposing the divided parts. In this case, the energy beams can be used fully and effectively. In the present invention, it is preferable to irradiate energy beams of high intensity to heat the magnetic layer in a short time, and for this purpose, it is preferable to use energy without loss.

6 is a view for explaining a method for splitting energy beams and an example of the intensity distribution of the energy beams. Suppose that energy beams having an elliptic beam shape have a distribution 201 in a short axis direction and a distribution 202 in a long axis direction. In this case, the difference in intensity can be dispersed, for example, by dividing the length of the beam into subdivisions in the uniaxial direction by a prism array (cylindrical lens) or the like and by superimposing the subdivided portions, so that in the uniaxial direction The intensity distribution of can be somewhat equalized. Further, the intensity distribution in the long axis direction can be somewhat equalized by dividing the length of the beams into seven parts in the long axis direction by a prism array (cylindrical lens) or the like and then superimposing the seven divided parts. Combining both, beams with overall good uniformity and small intensity distribution can be obtained. If necessary, it can be divided in only one axial direction. When the intensity distribution is large, the number of divisions must be increased to increase the uniformity.

When the energy beams are passed through two or more prism arrays having the same axial direction, the same effect as that of increasing the number of divisions can be obtained. Alternatively, intensity distributions in two axial directions can be simultaneously divided in two axial directions using a fly-eye lens having many lenses.

Alternatively, the intensity distribution can be easily equalized by passing the energy beams through an aspherical lens such as a cylindrical lens. In particular, when the energy beams have a small diameter beam, sufficient equalization can also be performed by using the above-described technique, and the optical system can also be simplified. Small diameter means a diameter of about 0.05 to 1 mm.

When equalization by the process described above is insufficient, a shading substrate may additionally be used to cut off the peripheral portions of the beams or to block the beams to provide additional equalization.

In the present invention, it is preferred that the energy beams are irradiated through a mask to locally heat the desired area. By using a mask, a magnetic pattern of a desired shape can be formed on the medium. Thus, a complicated pattern or a unique pattern that is difficult to form in the prior arts can be easily formed.

In phase servo systems for magnetic disks, magnetic patterns are used which, for example, extend inclined or linear with respect to the diameter of the tracks from the inner periphery to the outer periphery. By the conventional servo pattern forming method in which servo signals are recorded for each track while the disc is being rotated, it is difficult to form a pattern continuous in the radial reflection or inclined in the radial direction. However, in the present invention, complicated calculations or complicated devices are unnecessary, and such a magnetic pattern can be formed easily and in a short time by irradiating beams at the same time.

The mask is not necessary to cover the entire surface area of the magnetic disk, but may have repeating units for forming any size and magnetic pattern. Such a mask can be used to continuously move the mask to complete the desired pattern. Thus, the mask can be simple and inexpensive.

In order for the density (intensity distribution) of the energy beams to be formed on the surface of the magnetic disk, the mask may be such a mask that can change the intensity distribution of the energy beams to correspond to the magnetic pattern to be formed. By way of example, there is a photomask having a transmission portion for transmitting energy beams according to a pattern or a hologram mask in which a hologram for imaging a specific pattern is recorded on the medium. Such masks allow for the formation of multiple magnetic patterns or patterns of large surface areas at the same time, so that the magnetic pattern forming step can be easily performed in a short time. Although a clear and clear pattern can be formed using a hologram mask even when the mask is separated from the medium, the photomask is advantageous in view of ease and cost.

The material for the mask is not limited. However, when the mask is made of a nonmagnetic material, even if the mask is present in an arbitrary shaped pattern, a clear magnetic pattern can be formed uniformly, and uniform and strong reproduction signals can be obtained.

Since the distribution of the magnetic field is disturbed by magnetization, a mask made of a material containing ferromagnetic material is undesirable. In the case of a pattern inclined in the radial direction of the magnetic disk or a circular pattern extending in the radial direction of the magnetic disk, if a ferromagnetic material is used, since the external magnetic fields in the magnetic transition region do not have sufficiently opposite positions from each other, It is difficult to get high quality signals.

A mask is disposed between the energy beam light source and the magnetic layer (magnetic recording medium). When the precision of the magnetic pattern is considered to be dominant, it is desirable to contact a part or the entire part of the mask to the medium, whereby the influence of diffraction of the laser beams can be minimized, and a magnetic pattern having a high resolution is formed. Can be. For example, when the mask is placed on the medium, there is a portion in contact with the medium and a portion not in contact with the medium due to the relief of several micrometers on the surface of the medium. However, a pressure of 10 g / cm ² or less should be applied to the mask and the medium so that no signs or damages of compression occur in the medium.

In order to minimize the occurrence of damage or defects of the mask or the medium, it is preferable to form a space between the mask and the medium at least in an area for forming a magnetic pattern of the medium. Provision of space can suppress the occurrence of defects or damage in the medium or the mask, which defects are caused by deposition or intrusion of foreign matter such as dust. In addition, when the lubrication layer is formed before the formation of the magnetic pattern, it is particularly preferable that a space is formed between the mask and the medium to prevent the lubrication layer from being deposited on the mask.

As a method for maintaining the space between the magnetic pattern forming area of the magnetic recording medium and the mask, a method for holding both members at a predetermined distance exists. For example, specific means for keeping the mask and the medium at a predetermined distance can be used. Spacers may also be placed between the mask and the medium at locations other than the magnetic pattern formation region. In addition, the spacers may be integrally formed with the mask. When spacers are installed between the mask and the magnetic recording medium of the inner peripheral portion and / or the outer peripheral portion of the magnetic pattern forming region of the medium, they can correct the surface undulation of the magnetic recording medium, thereby Precision can be increased.

It is described in more detail with reference to the drawings.

First, an example of a method of forming a magnetic pattern using a photomask is described.

1 is a diagram illustrating an example of a magnetic pattern forming method using a photomask.

The magnetic disk 101 is uniformly magnetized in a direction along the circumferential direction by applying an external magnetic field in advance. Thereafter, the magnetic disk 101 is attached to the spindle 120. In particular, the disk is disposed on the turntable 101, and the photomask 102 is disposed on the disk by inserting the spacer 122. In addition, the compressed substrate 123 placed on the photomask 102 is fixed by screws (not shown). In other words, a space S is provided between the magnetic disk 101 and the photomask 102. Thereafter, the pulsed laser beams 103 are irradiated and an external magnetic field 104 is applied at the same time. The direction of the applied external magnetic field is opposite to the direction of the external magnetic field previously used for uniform magnetization.

A mask having a plurality of transmissive parts corresponding to the magnetic pattern to be formed can be used. Through such a mask, laser beams are irradiated onto the magnetic layer. In this case, it is preferable that the diameter of the beam is made large, or the shape of the beam is formed in an elliptical shape extending horizontally, and the laser beams are irradiated with a plurality of tracks or a plurality of sectors simultaneously with respect to the magnetic pattern. After that, the efficiency of recording can be further increased. In addition, the problem of an increase in the servo signal write time with the increase in the capacity can be improved.

The photomask may be such a mask provided with transmissive portions or portions and non-transmissive portions or portions in accordance with a desired magnetic pattern. Such a mask can be formed by sputtering a metal such as Cr on a transparent raw disk such as quartz glass or soda lime glass, coating a photoresist thereon, and etching the photoresist. Thus, certain transmissive portions and non-transmissive portions can be formed. In this case, portions having a Cr layer on the raw disk correspond to portions blocking the energy beams, and portions exposing the raw disk correspond to transmissive portions.

Typically, the mask thus produced has a non-uniform surface where the projection portions do not transmit energy beams. The projection portions are close to or almost in contact with the medium. Alternatively, a material for transmitting energy beams may be inserted in the recessed portions after formation of the mask such that the surface area that is slightly in contact with the medium is planarized.

The material for the spacer should be hard. Further, the spacer material is preferably not magnetized since an external magnetic field is used to form the pattern. Preference is given to using metals such as stainless steel or copper or resins such as polyimide. The height of the spacer is usually several micrometers or several hundred micrometers, although it is optical.

An example of a method of forming a magnetic pattern using a hologram mask is described.

2 is a diagram illustrating an example of a method of forming a magnetic pattern using a hologram mask.

As shown in FIG. 2 (a), the object light 107 is prism 108 through a photomask 106 in which transmissive and non-transmissive portions are formed in accordance with a magnetic pattern to be formed in the magnetic disk. One photopolymer 105 of the bed is irradiated. The reference light 109 is irradiated onto a single photopolymer 105 through a prism to record a hologram obtained by the interference between the target light 107 and the reference light 109 on the photopolymer 105.

Instead of using the photomask, a pattern to be exposed to light is obtained by calculation, and a hologram mask can be generated according to the result of the calculation.

When the reference light 109 is irradiated through the prism as shown in FIG. 2 (b), a pattern according to the holographic image is formed spaced apart from the photopolymer by a predetermined distance. By using this principle, laser light (reference light) 109 is irradiated from the laser light source 110 to the photopolymer 105 through the prism 108; The magnetic disk is disposed on a plane on which a pattern according to the holographic image is formed, and the reflective substrate 111 is moved to scan the reference light 109 on a single photopolymer 105, while simultaneously applying an external magnetic field 104. As a result, a magnetic pattern is formed (Fig. 2C).

When an external magnetic field is applied with heating, the external magnetic field must be applied simultaneously to the plurality of transmissive parts of the mask.

Since the minimum space between the mask and the magnetic recording medium is preferably 1 µm or more, contact of the lubricating layer with the mask can be avoided. The size of the dust, which is not easily attached to the magnetic recording medium or easy to remove by air-blowing, is typically smaller than 1 μm. In the case where the space is smaller than 1 m, the portion where the magnetic pattern is formed may be unexpectedly contacted with the mask by the undulation of the surface of the medium, and the mask or the magnetic recording medium may be damaged. Therefore, the space is more preferably 5 µm or more. In addition, the spacing should be 1 mm or less. When the spacing is larger than that value, the diffraction of the energy beams becomes large, and the magnetic pattern to be formed tends to be obscured.

For example, when an excimer laser (248 nm) is used to transfer a 2 × 2 μm pattern (a pattern having alternately 2 μm transmissive portions and 2 μm non-transmissive portions) formed in the photomask on the medium, the mask and the The distance between the media should be kept below about 25 to 45 μm. When the distance exceeds that value, the light and dark of the pattern become obscured by the diffraction phenomenon. In the case of a 1 × 1 μm pattern (a pattern having alternating 1 μm and 1 μm non-transmissive parts), the distance should be about 10 to 15 μm or less.

In the case of using a photomask, as the distance becomes longer, the distance between the mask and the medium becomes obscured by the deflection of the energy beams for irradiation, so that the magnetic pattern should be as short as possible within the above-mentioned range, and the magnetic pattern should be irradiated. It is obscured by the deflection of the energy beams for. In order to remedy this problem in order to obtain a clearer pattern, a slender transmissive portion or portions which function as a diffraction grating are formed on the outside of the transmissive portion of the mask or serve as a half-wave plate. Provided outside of the transmissive portion of the mask, the deflected light can be removed by interference.

On the other hand, when using a holographic mask, the distance of the imaging surface with respect to the pattern according to a holographic image is limited. Thus, the space for the medium is adjusted based on the distance. As shown in FIG. 2, the distance between the mask and the medium can be closer using a prism.

There are cases where magnetic layers are formed on both major surfaces of the disk relative to the magnetic disk. In this case, the magnetic pattern according to the invention is sequentially applied to each major surface or to both surfaces simultaneously by arranging means for applying an external magnetic field on both sides of the magnetic disk and energy irradiation systems, masks. Can be formed.

In the case where two or more magnetic layers are formed on a single surface and each different pattern is formed in each magnetic layer, the irradiated energy beams must be concentrated in each layer, and each layer is heated individually, Individual patterns can be formed.

In the case of forming a magnetic pattern, between the energy beam source and the mask or between the mask and the medium, re-irradiation of the energy beams is arranged by placing a shading substrate which can selectively block the energy beams in areas where irradiation is not desired. It is desirable to form a structure for preventing.

For the shading substrate, such a shading substrate is sufficient to block any wavelength of the energy beams used, and this is sufficient to reflect or absorb the energy beams. However, since the heat is generated by absorbing the energy beams and the heat adversely affects the formation of the magnetic pattern, it is preferable that the shading substrate has excellent thermal conductivity and high reflectivity. For example, a metal substrate such as Cr, Al, Fe, or the like may be used.

It is also desirable for reduced image forming techniques to be used in optical systems. An image is formed on the medium surface by reducing patterned energy beams having an intensity distribution corresponding to the magnetic pattern to be formed. According to this technique, the precision of the magnetic pattern, which depends on the precision of the alignment or patterning of the mask, is determined when the energy beams are controlled by the objective lens and after which the adjusted beam is passed through the mask, i.e. in the case of approximate exposure of light. It is not limited in comparison with. Thus, finer magnetic patterns can be formed with excellent precision. In addition, since the mask is separated from the medium, there is little possibility that it can be affected by dust. In the following, this technique may be referred to as a reduced image forming technique (imaging optical system).

The intensity distribution of the energy beams emitted from the beam source is altered by the mask to form a reduced image on the surface of the medium through imaging means such as imaging lenses. Hereinafter, the imaging lens may be called a projection lens, and the reduced image may be called a reduced projection.

The mask can be such a mask that can provide energy beams of any grade of intensity (density) on the medium, depending on the magnetic pattern to be formed. Such a mask can be a photomask in which the transmissive and non-transmissive portions of the energy beams are formed in accordance with the pattern or a hologram mask in which a hologram is recorded, for example to form an image of a pattern specified on the medium.

In the above-described technique, an imaging means is provided between the mask and the medium. In the prior art, when energy beams are irradiated onto the medium with which the photomask is in contact, the mask can be heated by absorbing energy beams depending on the material used, and the medium in close contact with the photomask. The temperature of the surface is also increased so that a clear magnetic pattern cannot be provided. However, according to the present invention, such a problem can be eliminated.

That is, the medium surface on which the magnetic pattern is formed should have a large temperature difference between the time of irradiating pulsed energy beams and the time of not irradiating, in order to increase the contrast ratio of the pattern or increase the recording density. Thus, at times when irradiating pulsed energy beams, the medium surface is preferably present at or below room temperature, where the room temperature is about 25 ° C.

In addition, energy beams are introduced into the mask via the condensing lens, and the intensity distribution of the energy beams can be equalized, so that the energy beams can be effectively introduced into the imaging lens.

As long as the minimum beam diameter of the energy beams and the maximum intensity of the external magnetic field are available, the reduced image forming technique can be applied to form a magnetic pattern of any size or any shape. Finer magnetic patterns provide a higher effect. When the minimum width of the magnetic pattern is 2 μm or less, the alignment process of the mask becomes more difficult. In this case, it is preferable that the above-described technique is used. More preferably, the minimum width is 1 μm or less. There is no lower limit to the size of the pattern to be formed. In theory, a fine pattern can be formed by using almost a limit wavelength of energy beams. For example, the wavelength of the excimer laser is about 10 nm.

In addition, according to this technique, finer magnetic patterns can be formed by forming a reduced image. Thus, this provides a great effect for the application of the control pattern formation used to control the data recording / reproducing head.

According to this technique, a reduced image is formed by the imaging means through the mask. Therefore, when the reduction ratio becomes large, a finer pattern can be formed. In this case, however, by adjusting the beam, the beam diameter of the energy beams is made small, and the area where the pattern is formed at the same time is made small. Therefore, this technique is suitable for high density and small diameter magnetic disks, especially magnetic disks having a diameter of 65 mm or less.

Usually, a small diameter magnetic disk has a very large recording density since it is required to have a large recording capacity even if it has a small recording surface area. This technique is preferably used for magnetic disks with a diameter of 1.8 inches or less, especially 1 inch or less.

For example, data can be recorded simultaneously on a very small magnetic disk having a diameter of less than 1 inch. In the case of a vertical magnetic recording type magnetic disk, an external magnetic field can be easily applied to the whole of the disk, so that information can be immediately recorded on the entire surface.

Notwithstanding the above, this technique can be applied to a magnetic recording medium having a large diameter, such as a magnetic recording medium having a diameter of 3.5 inches. In this case, the shape of the beam is formed to have a side extending ellipse shape, and magnetic patterns for a plurality of tracks or a plurality of sectors are irradiated at once, so that recording efficiency is increased, servo signals are recorded by the magnetic head, and In comparison with the conventional technique in which the precision is increased, the servo signal writing time can be effectively shortened.

In the present invention, irradiation can be performed by scanning energy beams on the medium, so that a wider area can be irradiated in a short time even when the beams are adjusted to have a small diameter. For example, by placing a portion or all of the energy beam irradiation optical system on the slider that is moved, scanning by the beam may be performed. Alternatively, galvanometers or f-theta lenses can be used. By introducing the energy beams through the galvanometer into the f-θ lens while the angle of the galvanometer is changed, the beams can be scanned into the medium. In order to scan a wider range in a short time, it is desirable to generate a short pulse of energy beam at high speed.

In the present invention, preferably, the pulsed energy beams are irradiated while the mask and energy beam irradiation spot for the magnetic recording medium is relatively moved, wherein the pulsed energy beams are irradiated in synchronization with the relative movement. do.

Since the area where the energy beams can be irradiated at the same time is limited to about tens to tens of mm, it is difficult to irradiate the entire surface of a magnetic disk having a diameter of 3.5 inches or 2.5 inches at the same time. Thus, by continuously scanning the medium surface, a method of irradiating energy beams can be considered. However, according to this method, double irradiation of energy beams or long time irradiation to the same position is likely to occur.

In the contemplated method, a disc shaped mask is fixed coaxially to the disc, the disc is divided into a plurality of fan shaped virtual regions, and pulsed energy beams are irradiated once through each mask to each sector. do. In this case, the disk and the mask are rotated together at a slow speed, and the pulsed energy beams are irradiated in synchronization with the rotation speed. When the angle of the sector of the region is 12 degrees, the disk is rotated at 2 rpm (1 rotation in 30 seconds), and the energy beams are irradiated at a frequency of 1 kHz in a timely manner, so that the synchronization of irradiation and rotation can be obtained. . The rotation speed can be kept constant using an encoder or the like.

As another method, a fan mask is placed on the disk and one pulse of one of the pulsed energy beams is applied to the fan-shaped virtual region of the disk through the mask. Thereafter, only the mask or disk is rotated so that after it is rotated at an angle, a pulse of one of the beams is applied through the mask to an adjacent sector of virtual sector. When the angle of the sector is 12 degrees, the disk or mask is rotated at 2 rpm (once every 30 seconds), and synchronization of irradiation and rotation can be obtained by timely irradiation of energy beams at a frequency of 1 kHz. . The rotation speed can be kept constant using an encoder or the like.

When the pulse width of the energy beams is short enough, the disk can be rotated continuously during irradiation of the energy beams. However, a method of irradiating the disk by intermittently stopping the disk so that the degree of clearness of the magnetic pattern can be increased is preferred.

According to the present invention, double irradiation of the energy beam to the same position can be prevented. Therefore, deterioration of signals due to thermo-demagnetization, opacity of the boundary of the magnetic pattern by the heat storage device, or damage to the medium can be minimized, so that a precise magnetic pattern without defects can be effectively formed. have.

In a preferred method of forming a magnetic pattern, pulsed energy beams are irradiated and irradiated with the pulsed energy beams, while the position of the mask and / or magnetic recording medium and the energy beam irradiation spot are relatively moved. By performing detection, relative movement and detection of such relative movement in sequence, double irradiation of energy beams to the same position can be prevented.

For example, as soon as the pulsed energy beams are oscillated, an oscillation signal (external trigger signal, etc.) is obtained, and after detecting the oscillation signal, the motor for moving the magnetic recording medium is moved to a desired position. It is operated to rotate / move (relatively move). When a signal is detected indicating that relative movement is complete, the detection signal is supplied to an energy beam generation source. The detection signal is used as a trigger signal to generate a subsequent pulsed energy beam. Synchronization may be obtained by repeating such operations.

In the present invention, although the present invention is not limited again, some methods for relatively moving the energy beam irradiation spot and the mask and / or the magnetic recording medium may be considered.

For example, an energy beam irradiation spot is fixed, and the medium is moved by a motor or the like together with or independently of a mask attached to the spindle. Alternatively, the medium and the mask are fixed on the parallel slider which is moved in the parallel direction by a motor or the like. When the medium is present in the form of a disc, ie when a magnetic disc is used, it is recommended to rotate the magnetic disc in the simplest and most accurate way.

Conversely, there is a method for moving an energy beam irradiation spot while the medium and the mask are fixed. For example, part or all of the energy beam irradiation system may be installed on the slider to be moved. Alternatively, provided that the angle of the energy beams is changed by a galvanometer or dichroic mirror installed in the energy beam irradiation system, the energy beam irradiation spot may be moved using an f-θ lens or the like.

In addition, a combination of the above-described methods may be used. When the beam diameters of the energy beams are small, it is sometimes difficult to simultaneously irradiate the entire area in the radial direction of the magnetic disk. In such a case, the magnetic disk and the mask are fixed on parallel sliders, and the magnetic disk is moved relatively in its radial direction to perform several irradiations, so that the entire area can be irradiated.

For example, the energy beam irradiation system installed on the slider is typically moved in the radial direction to rotate the disk and the mask and to perform irradiation at the same time. Alternatively, the energy beam irradiation spot can be moved to irradiate in the radial direction, subject to rotation of the disk and the mask and at the same time the angle of the energy beams is typically changed by a dichroic mirror or galvanometer. .

Alternatively, the following steps may be repeated: the energy beam irradiation spot is moved radially to completely irradiate the disk, the disk and the mask are rotated slightly, and at the same time the energy beam irradiation spot is irradiating the disk completely. Is moved in the radial direction.

In order to scan large areas at the same time as short as possible, it is desirable to generate short pulses of energy beams at high speed. Thus, while the magnetic recording medium is relatively moved, a magnetic pattern can be formed by irradiating pulsed energy beams onto the entire surface of the medium.

When the pattern to be formed on the medium is recorded in a single mask, the mask is fixed to the medium, the mask and the medium are moved together, and pulsed energy beams are irradiated onto the medium while moving. In pattern formation having no periodicity in the circumferential or radial direction of the disk, a single mask is suitable for the magnetic disk.

When the pattern formed on the medium repeatedly exists in the unit pattern, the irradiation of the pulsed energy beams is performed by moving only the magnetic recording medium without moving the mask on which the unit pattern is formed or without moving the medium. By moving only the mask. In forming a pattern having periodicity in the circumferential or radial direction of the disk, this method is suitable for the magnetic disk. More preferably, the relative movement comprises the rotation of the medium or the mask.

In order to match the direction of magnetization in the so-called horizontal magnetic recording type disc with the circumferential direction of the magnetic recording medium, rotation is more suitable than parallel movement.

Using energy beams, in order to achieve synchronization of the magnetic recording medium and / or mask, the number of irradiations required to print the pattern on the entire surface of the magnetic recording pattern is first obtained by calculating the energy beams based on the surface area to which they are irradiated. ; The optimal repetition frequency is selected based on the repetition oscillation frequency applicable to the energy beams and the time for forming the pattern, and the rotational speed without double irradiation and the speed of parallel movement are determined.

An energy beam irradiation system means part or all of an optical system, such as a lens and / or a mirror, which introduces energy beams radiated from an energy beam source into a magnetic recording medium. For example, this includes an objective lens, a convex lens, a galvanomirror, a dichroic mirror, and the like, for irradiating a laser emitted from a light source to a magnetic recording medium.

The shape of the irradiation energy beams emitted from the light source is preferably changed to the desired shape by optical processing. In the application of the magnetic disk, the shape of the beams is preferably fan-shaped. In addition, it is desirable to optically equalize, expand, reduce or alter the energy beams to meet the shape of the substrate. Optical homogeneity of the energy beams in which the energy distribution is even at the beam spot can be achieved by the homogenizer. Optical expansion of the energy beams can be achieved by a beam expander in which the beams extend in any direction.

In the present invention, when energy beams are irradiated to the medium through a mask, the energy beams are absorbed into the mask, so that the temperature of the mask is increased to cause thermal expansion depending on the conditions, thereby per unit area. The amount of error increases. Therefore, it is desirable to cool the mask when the energy beams are irradiated onto the medium through the mask. Using such means, thermal expansion of the mask can be prevented and the desired magnetic pattern can be formed precisely with minimal dimensional error.

The means for cooling the mask may be a system (air cooling system) for supplying an air stream to the mask, a system for rotating coolant (water cooling system), a system using another coolant, and the like. . The heat generated by the irradiation of energy beams in the mask can be sufficiently removed. For example, an air gun may be disposed in the vicinity of the mask, air may be supplied to the surface of the mask to which the energy beams are irradiated, or the pipe may be arranged such that coolant rotates around the mask. .

In addition, the mask can be cooled from any side surface, such as a side surface or a back surface, a surface to which energy beams are irradiated, and the location of the cooling is not limited. However, cooling in or near the area where the energy beams are directly irradiated (adjacent area) is more effective because the temperature rise in that area is large.

When the pulsed energy is irradiated, the irradiation time and non-irradiation time are alternately repeated. Cooling can be performed only at the irradiation time, only at the non-irradiation time, or both as needed. When cooling at the irradiation time, it is necessary to use cooling means that do not shield the mask. However, it is not taken into account when cooling is performed only in non-irradiation time.

In addition, the conditions for cooling can be controlled depending on the detected temperature so that the temperature of the mask can be monitored by a temperature sensor or the like so that the temperature can be kept constant. For example, in the water cooling system, the cooling time, the water temperature and the like can be controlled, and in the air cooling system, the cooling time, the air amount, the air temperature and the like can be controlled.

The gas used in the air cooling system can be any gas as long as the mask is not damaged. For example, an injection gas such as N, Ar or air can be used. Air is preferred from the point of view of cost. In particular, in view of minimizing errors in printing, air in which fine particles, dust, etc. are removed by using clean air or a filter is used. The mask is cooled by firing clean air from the air gun.

In a water cooling system, it is desirable to be in contact with water, which is temperature controlled to part or the entire area of the mask by inserting a metal member or water bag having high temperature conductivity.

When using a water cooling system or another coolant, care must be taken to avoid condensation on the mask in order to transmit energy beams without reducing the function of the mask. For this purpose, it is desirable to reduce the ambient temperature.

By maintaining the temperature of the mask in a predetermined range using such cooling means, thermal expansion of the mask can be prevented and the magnetic pattern can be formed more precisely. The temperature of the mask is preferably maintained at 0 ℃ to 30 ℃. However, when pulsed energy beams having high peak values are irradiated, the temperature of the mask rises rapidly for a while. Thus, in the irradiation of energy beams, there are cases where the temperature cannot be maintained in the above-mentioned range.

This method is preferably carried out in an environment such as in a clean room where fine particles, dust, temperature and humidity are controlled. As for ambient temperature, 0-30 degreeC is preferable.

In the case where a magnetic recording medium is supported by a medium supporting means such as a spindle, a guide, a crimped substrate, or the like, energy beams are irradiated to the medium supporting means, so that the medium supporting means absorbs the energy beams and causes the temperature rise. Thermal expansion occurs, causing the measurement error to be larger than the expected dimensions. For example, when the spindle or compressed substrate is thermally expanded, the eccentricity of the medium becomes large.

Therefore, the medium supporting means must be cooled to minimize the eccentricity, and the precise magnetic pattern can be formed with little error. Preferably, the precision is increased by removing heat generated in the mask and the media means.

The medium support means represents the whole mechanism for supporting the medium. In particular, it includes spacer (s) and turntables other than the members described above. The area to be cooled may be part or all of the support means, but it should include an area to which energy beams are irradiated or an area which is easy to be heated by irradiation.

The materials used for the medium support means can be any as long as the materials have sufficient strength to sufficiently support the magnetic recording medium. However, it is desirable to use materials that are thermally stable in dimensions, such as metals, alloys, resins, ceramics, glass, and the like. In particular, metals or alloys are preferred in view of being able to disperse heat generated by energy beams in a short time. In particular, metals or alloys having large heat dissipation properties are preferred.

The means for cooling the medium support means and the conditions for cooling are the same as the means and conditions for cooling the mask. However, the methods and conditions for cooling the medium support means may be different from those of the mask cooling means. The region to which the energy beams are directly irradiated can be directly cooled or the vicinity of the region can be cooled by thermal conduction. Directly supplying clean air at about 20 ° C. at a rate of 2 kgf / cm ^{2 with} an air gun directly to the rear surface of the mask and the medium support means, compared to the case without The degree can be increased. For example, it is found that using a pattern having a width of 1 m improves the pattern precision of about 0.1 m.

Next, the external magnetic field will be described.

When a circular disk-shaped medium is used, the direction of applying the external magnetic field is preferably any of the directions perpendicular to the surface of the medium and between the radial and circumferential directions.

When an external magnetic field is applied with heating, the external magnetic field can be applied over a wide area to be heated. Thereby, a plurality of magnetic patterns can be formed at the same time.

As means for applying an external magnetic field to the magnetic layer, a plurality of electromagnets or permanent magnets may be arranged, or a magnetic head may be used to generate a magnetic field in a predetermined magnetization direction. In addition, a combination of other means may be used as described above. In order to effectively magnetize a medium having high coercivity suitable for high density recording, permanent magnets such as ferrite magnets, neodymium-type rare earth magnets, samarium-cobalt-type rare earth magnets and the like are preferable.

29 shows an example of the arrangement of permanent magnets used to apply an external magnetic field in the circumferential direction of a 2.5 inch magnetic disk.

A plurality of NdFe magnets each having a magnetic field strength of 1.9 k Gauss are disposed in two opposing lines with magnetic poles opposing each other on a magnetic yoke 67 as shown in FIG. 29. . The dimensions of each of the magnets are 6.0 mm x 6.0 mm x 6.0 mm. The end of the magnet located in the innermost periphery is disposed 10 mm away from the center of the disk, and the other magnets are adjacent to the magnet in the radial direction such that the lined magnets extend radially at an angle of 6 degrees. Are arranged continuously. The distance between the disk and the magnets is determined to be about 5 mm so that the magnetic field strength applied to the disk at the center between the opposing magnets 63, 63 'is 1.3 k Gauss. The measurement of the magnetic field strength is performed in the vicinity of each magnet on the linear line connecting the N and S poles of the opposing magnets.

When a medium such as a circular disk is used, it is preferable to change the magnetic field strength of the external magnetic field applying means along the radial direction of the medium. In forming a magnetic pattern in a medium such as the circular disk by irradiating energy beams with magnetic application, it is an effective method to divide the recording area into sectors.

In a medium in which recording is performed at a constant angular speed by rotating a medium such as the circular disk, the linear recording density is lower toward the outer periphery. When recording is performed by rotating at a constant angular speed, the length for recording of the magnetic area becomes longer toward its outer periphery. Thus, when forming a magnetic pattern in each track of the medium, the pattern extends in a fan shape toward the outer circumference.

Thus, the application of the magnetic field is carried out in the radial direction to substantially cover the sector.

When a general magnet, i.e., a magnet having a uniform magnetic field strength, is used to apply a magnetic field to a sector, the magnetic field force actually applied to the disk becomes smaller toward the outer circumference, and the longer the distance between the opposing magnetic poles becomes. The longer it becomes, the smaller the strength of the magnetic field is, so it is difficult to form a magnetic pattern clearly.

Therefore, the magnetic field strength of the external magnetic field applying means must be changed depending on the positions on the disc in the radial direction thereof. Thus, the magnetic field strength actually applied to the disk can be made uniform, and the magnetic pattern can be formed clearly and uniformly on the entire surface of the disk.

This method is particularly effective when the irradiation of energy beams and the application of a magnetic field are performed simultaneously. If the application of the magnetic field is carried out twice, ie before the irradiation of the energy beams and with the irradiation, this method can be used for either or both.

The magnetic field strength can be changed linearly, curvedly or stepwise. In addition, there is a difference of at least 5% between the maximum value and the minimum value of the magnetic field strength. Even if there is no upper limit in the value, when using a 2.5 inch magnetic disk, the difference is preferably about five times or less.

In the case of using an electromagnet, the number of turns and the density of the coil are changed in the radial direction so that the magnetic field strength can be easily changed. The magnetic field strength can be varied by varying the number of turns and the density of the coil in a single electromagnet or by placing the electromagnets with the coil's density and other number of turns in the radial direction. Different magnetic intensities can be easily provided to the inner and outer circumferential portions by changing the magnetic field intensities of the individual magnets, so a structure comprising a plurality of permanent magnets is desirable. In addition, various arrangements are possible. The kind of magnets that can be used may be such magnets that can provide the desired magnetic field.

Preferably, the external magnetic field applying means includes two magnetic field applying means having different magnetic polarities, and both applying means face the same plane of the magnetic recording medium. Such arrangement can be simplified. When two applying means are arranged radially in the radial direction of the magnetic recording medium, the magnetic pattern can be formed uniformly in the radial direction of the magnetic recording medium without generating skew loss.

For example, the same permanent magnets are disposed along the circumferential direction of the innermost circumference of the disk to face the magnets in pairs of the N pole and the S pole. Other permanent magnets with stronger magnetic field strength are placed adjacent to these magnets to increase the distance between the magnetic poles. In addition, other permanent magnets having even stronger strength are disposed adjacent to the second permanent magnets, increasing the distance between the magnetic poles. By repeating such an operation, the final permanent magnets reach the outermost part of the disk. Thereafter, a series of magnets having N poles at the outer free end and a series of magnets having S poles at the outer free end are arranged substantially radially.

A U-shaped permanent magnet having both ends of the N pole and the S pole may be arranged such that the two ends face each other.

The term “substantially radial” includes forms of linear and curved radiation, meaning that the distance between the magnetic poles increases gradually in the direction of the circumference. In particular, it is effective to satisfy the shape in a fan shape in the magnetic recording medium. For example, the magnetic pattern is formed in a magnetic recording medium such as a circular disk over the entire outer circumference by dividing at an arbitrary angle, or by rotating the magnetic recording medium.

In addition, when the magnetic field strengths of the opposing magnetic poles are substantially the same, this simplifies the arrangement and structure.

In the present invention, the magnetic field strength means the maximum magnetic field strength of the external magnetic field applying means, which is a value measured at a position very close to the means. For example, it is measured in the vicinity of the magnetic pole of either one on the linear line connecting the N pole and the S pole.

30 and 31 show examples of the arrangement of permanent magnets in the case described above.

Two sets of NdFe magnets each having a magnetic field strength of 2.7k Gauss, 2.3k Gauss, 1.9k Gauss have polarities opposite to each other by inserting the magnetic yoke 67 as shown in FIG. Placed in two lines in opposite state. The dimensions of each of the magnets are 6.0 mm x 6.0 mm x 6.0 mm. The end portion of the magnet located at the innermost circumference is disposed 10 mm away from the center of the disk, and the other magnets are disposed adjacent to the magnet in the radial direction of 6 degrees. The distance between the disk and the magnets is determined to be about 5 mm so that the magnetic field strength applied to the disk at the center between the magnets 63, 63 'is 1.3 k Gauss. Thus, the magnetic distribution at the center on the linear line connecting the paired magnets can be maintained in the range of 1.2 k Gauss to 1.6 k Gauss. As a result, output scattering of the formed pattern can be suppressed.

Alternatively, two sets of NdFe magnets each having magnetic field intensities of 2.7k Gauss, 2.3k Gauss, 1.9k Gauss, 1.6 Gauss, 1.4 Gauss and 1.2 Gauss are opposed to each other on magnetic yoke 67 It is arranged in two lines in opposing states using magnetic poles. The dimensions of each of the magnets are 5.0 mm x 5.0 mm x 5.0 mm. The end portion of the magnet located at the innermost circumference is disposed 10 mm away from the center of the disk, and the other magnets are arranged in a radial direction of 6 degrees. The distance between the disk and the magnets is determined to be about 4 mm so that the magnetic field strength applied to the disk at the center between the magnets 63, 63 'is 1.3 k Gauss. Thus, the magnetic field distribution at the center on the line connecting the paired magnets can be maintained in the range of 1.2 k Gauss to 1.6 k Gauss. As a result, scattering of the output of the formed pattern can be suppressed.

In the magnetic pattern formation method of this invention, it is preferable that a 2nd lubrication layer is formed after formation of the said magnetic pattern. When a magnetic pattern is formed by combining application of an external magnetic field and local heating, the lubrication layer on the magnetic recording medium is heated and partially evaporated. It can also be reduced by attaching the lubrication layer to the mask.

Reduction of the lubrication layer reduces the impact resistance or durability against the magnetic head. Thus, after the magnetic pattern is formed by combining local heating and application of an external magnetic field, the lubrication layer is formed again by forming a lubrication layer of sufficient layer thickness, so that durability and high impact resistance to the magnetic head can be achieved. .

As described above, according to the present invention, a precise magnetic pattern can be formed. Thus, such a method is very effective when applied to the formation of the control pattern used to control the data recording / reproducing head. In particular, the control pattern includes a servo pattern or a reference pattern for recording the servo pattern.

Further, according to the present invention, since the high signal strength can be obtained even when the magnetic pattern includes a pattern extending obliquely to the tracks as described above, the present invention is suitable for forming an inclination pattern for a phase servo signal or the like. Do.

The pattern extending obliquely is a pattern having an arbitrary inclination with respect to the reference line, wherein the reference line is present along a direction perpendicular to the moving direction of the head. Since the slope of the reference line is preferably within ± 45 degrees, signals that can be effectively used as servo signals can be generated. That is, the signal from the magnetic pattern formed in accordance with the present invention can be used directly to check for defects on the medium. The recording step can be saved upon inspection of the defects, and the manufacturing time can be shortened to reduce the manufacturing cost.

According to the present invention, a magnetic pattern having a high quality output signal can be formed accurately and effectively by optimizing the above-described conditions. That is, a pattern having a high quality output signal in which the width of the magnetic transition is small and the magnetic transition at the boundary of the magnetic regions is very sharp can be formed. By selecting the conditions, it is possible to obtain a width of magnetic transition of 1 m or less, preferably 0.5 m or less, more preferably 0.3 m or less. In the present invention, the width of the magnetic transition is reproduced by the magnetic head, and means the pulse width (ie, half width) of the reproduced signal waveform with 50% of the maximum magnetization of the reproduced signal waveform of the magnetic pattern. .

In particular, when a reduced image forming technique is used, the precision of the magnetic pattern is not limited by the precision of alignment or patterning of the mask. Thus, additional fine magnetic patterns can be accurately formed.

In addition, the magnetic pattern can be easily formed in a very short time, and unlike the prior art, since it does not come into contact with the master disk, damage or defects are rarely generated.

In particular, because of the request to increase the density of the recording, the recording of the servo signals becomes difficult, and the recording of the servo signals mainly affects the manufacturing cost. Therefore, the application of the present invention to a medium for recording data of high density yields a great effect. Further, the present invention can be easily applied to a vertical magnetic recording medium because the magnetic field can be easily applied.

Next, the structure of the magnetic recording medium of the present invention is described.

Since the substrate of the magnetic recording medium of the present invention should not generate vibration even at high speed when reproducing signals at high speed, a hard substrate is usually used. In order to obtain sufficient strength for vibration, the thickness of the substrate is preferably 0.3 mm or more. However, thicker substrates contradict the request to reduce the thickness of magnetic recording devices. Therefore, 3 mm or less is preferable. For example, Al alloy substrate containing Al as a main component, such as Al-Mg alloy substrate; Mg alloy substrate containing Mg as a main component, such as Mg-Zn alloy substrate; There is a substrate made of a material such as conventional soda glass, aluminum silicate glass, amorphous glass, silicon, titanium, ceramic or various resins or a substrate produced by combining such materials. In particular, it is preferable to use a substrate composed of glass such as crystallized glass from the viewpoint of strength or a substrate composed of resin or an Al alloy substrate from the viewpoint of cost.

The present invention has a remarkable effect in application to a medium having a hard substrate. In the conventional magnetic permeation method, if the medium having a hard substrate is insufficiently contacted with the master disk, flow or defects may occur, or the transition of the printed magnetic area may be unclear, so that the PW50 may be expanded. . On the other hand, the present invention does not cause such a problem because the mask is not in press contact with the medium. In particular, the present invention is effectively used for a medium having a glass substrate which is susceptible to cracks.

In conventional manufacturing steps for a magnetic disk, cleaning and drying are typically performed on the substrate. From the standpoint of maintaining the contact properties of each layer, it is preferred in the present invention that cleaning and drying are performed prior to formation of the layers. In manufacturing the magnetic recording medium of the present invention, a metal layer such as NiP can be formed on the surface of the substrate.

As a method for forming the metal layer, a technique for forming a thin film such as an electroless plating method, a sputtering method, a vacuum deposition method, a CVD method, or the like can be used. When a substrate made of an electrically conductive material is used, an electroplating method can be used. The thickness of the metal layer is preferably 50 nm or more. However, in consideration of the productivity for the magnetic disk medium, the thickness thereof is preferably 500 nm or less, more preferably 300 nm or less.

It is also desirable to form a metal layer on the entire substrate surface. However, it is possible to form the metal layer only in part, for example, only in the region where texturing is performed.

In addition, texturing may be formed concentrically on the surface of the non-magnetic metal layer formed on the substrate or on the surface of the substrate. In the present invention, the term “concentrically texturing” refers to the circumferential direction, for example, by using mechanical texturing with abrasive grains and texturing tape, texturing with laser beams or by a combination of these techniques. By grinding the substrate, a plurality of fine grooves are formed in the circumferential direction of the substrate.

As a kind of abrasive grain for mechanical texturing, such grains having diamond grains, in particular graphatized surfaces, are most preferred. As another grain used for mechanical texturing, alumina grains are widely used. However, in view of the fact that the horizontally oriented medium has a property of providing an easy magnetization axis directed along the texturing grooves, diamond grains exhibit excellent performance.

A method of reducing the flying height of the head as far as possible is effective for realizing high density recording. In addition, flatness or smoothness is one of the properties of the substrate. Therefore, the surface roughness Ra of the substrate surface is preferably 2 nm or less, more preferably 1 nm or less, even more preferably 0.5 nm or less. The surface roughness Ra is a value obtained by measuring a length of 400 μm using a contact finger type surface roughness meter and by calculating a value measured according to JIS B0601. In this case, the size of the finger tip used for the measurement is about 0.2 μm.

An underlayer may be formed between the magnetic layer and the substrate. The underlayer produces fine crystals and controls the orientation of the crystal plane. For this purpose, it is preferable to use a material containing Cr as the main component.

With respect to the material for the lower layer containing Cr as a main component in addition to pure Cr, the material is selected from V, Ti, Mo, Zr, Hf, Ta, W, Ge, Nb, Si to obtain excellent crystals that match the recording layer. And alloys composed of one or more devices selected from the group consisting of Cu, B or chromium oxide.

Among them, alloys obtained by adding one or two or more components selected from the group consisting of Ti, Mo, W, V, Ta, Si, Nb, Zr and Hf to pure Cr or Cr are preferred. Although the optimum amount varies depending on the components used, the contents of the second and third components are generally preferably 1 atomic% to 50 atomic%, more preferably 5 atomic% to 30 atomic%, and 5 Even more preferred are atomic percent to 20 atomic percent.

The thickness of the lower layer should have such a thickness to be sufficient to realize anisotropy, which is preferably from 0.1 to 50 nm, more preferably from 0.3 to 30 nm, even more preferably from 0.5 to 10 nm. When the lower layer containing Cr as a main component is formed, the substrate may or may not be heated.

Depending on the conditions, a soft magnetic layer can be formed between the lower layer and the recording layer. The formation of the soft magnetic layer has a great effect, in particular, it is preferably used for a keeper medium or a vertical recordable medium which reduces magnetic transition noise, the magnetic regions being in a direction perpendicular to the horizontal direction of the medium. Headed.

The soft magnetic layer may be composed of a material having a relatively high magnetic permeability and a small magnetic loss. However, it is preferable to use a material of an alloy or NiFe alloy to which Mo or the like is added as the third component. The optimum magnetic permeability varies greatly depending on the characteristics of the recording layer or the head used to record the data. Typically, a maximum magnetic permeability of about 10 to 1,000,000 (H / m) is preferred.

In addition, a series of CoCr inner layers may be formed on the Cr underlayer.

Then, in forming the recording layer (magnetic layer), a layer made of the same material as the lower layer or a layer made of non-magnetic material can be inserted between the recording layer and the soft magnetic layer. When the recording layer is formed, the substrate may not be heated. As the recording layer, it is preferable to use a magnetic alloy of Co alloy, a rare earth magnetic layer denoted by TbFeCo, or a multilayer of a transition metal such as a multilayer of p and a pd layer and a precious metal.

The magnetic layer of the Co alloy may be composed of a pure Co or Co alloy magnetic material, which is commonly used as a magnetic material CoNi, CoSm, CoCrTa, CoNiCr or CoCrPt. In addition, SiO ₂ A mixture such as or a component such as Ni, Cr, Pt, Ta, W or B may be added to the Co alloy described above. For example, CoCrPtTa, CoCrPtB, CoNiPt, CoNiCrPtB and the like can be mentioned. The magnetic layer thickness of the Co alloy is optional, but its thickness is preferably at least 5 nm, more preferably at least 10 nm. In addition, two or more recording layers may be formed by inserting a suitable non-magnetic interlayer or without any intervening layer. In this case, the composition of the magnetic material to be formed may be the same or different.

As the magnetic material for the rare earth type magnetic layer, a material commonly used may be used. TbFeCo, GdFeCo, DyFeCO or TbFe may be mentioned, for example Tb, Dy or Ho may be added to such rare earth alloys. Ti, Al or Pt may be added to prevent deterioration by oxidation. Although the thickness of the rare earth-type magnetic layer is optional, a thickness of about 5 to 100 nm is commonly used. Also, two or more recording layers may be formed directly or by inserting a suitable nonmagnetic interlayer film. The composition of the magnetic material to be formed may be the same or different. In particular, the rare earth magnetic layer is a layer having an amorphous structure, and may be magnetized perpendicularly to the surface of the medium. Therefore, the method of the present invention suitable for high density recording and capable of forming a magnetic pattern with high density and high accuracy is effectively applicable.

In addition, the multilayer composed of vertical magnetic recordable transition metals and precious metals may be composed of conventional magnetic materials such as Co / pd, Co / Pt, Fe / Pt, Fe / Au or Fe / Ag. The transition metal and the noble metal for the multilayer need not always be pure, but may be an alloy containing such material as the main component. Although the thickness of the laminate layer is optional, it is typically about 5 to 1000 nm. In addition, the multilayer may be formed of three or more materials as necessary. In the present invention, when the thick recording layer is heated, the thick recording layer worsens thermal conduction in the layer thickness direction, so that the recording layer is preferably thinner, whereby the desired magnetization can be obtained. Therefore, the thickness of the recording layer is preferably 200 nm or less. However, in order to maintain excellent magnetization, the thickness is preferably 5 nm or more.

As the recording layer of the present invention, the magnetic layer maintains its magnetism at room temperature and is magnetized by application of heat or by application of an external magnetic field with heating.

The coercive force of the magnetic layer at room temperature needs to be kept magnetic at room temperature and magnetized uniformly with an appropriate external magnetic field. By making the coercive force of the magnetic layer at room temperature to be 2000 Oe or more, a medium having small magnetic regions and suitable for high density recording can be obtained. In particular, the coercive force is 3000 Oe or more.

In the conventional magnetic transfer method, it is difficult to transfer the pattern to a medium having a higher coercive force. However, since the magnetic pattern is formed by heating the magnetic layer to sufficiently reduce the coercive force, the present invention is suitably applied to such a pattern having a large coercive force.

However, the coercive force is preferably 20 kOe or less. When the coercive force exceeds 20 kOe, a large external magnetic field is required to magnetize the magnetic layer at once. In addition, normal magnetic recording becomes difficult.

The magnetic layer needs to be magnetized to a weaker external magnetic field at a suitable heating temperature while maintaining magnetism at room temperature. In addition, the magnetic regions of the magnetic pattern can be made clear by increasing the difference between the room temperature and the magnetization cancellation temperature. For this purpose, it is preferable that the magnetization erasing temperature is higher, in particular, the temperature is preferably at least 100 ° C, more preferably at least 150 ° C. For example, the magnetization elimination temperature is in the vicinity of the Curie temperature (slightly lower than the Curie temperature) or in the vicinity of the compensation temperature.

As for the said Curie temperature, 100 degreeC or more is preferable. When the temperature is lower than 100 ° C, the safety of the magnetic regions at room temperature tends to be low. Therefore, when the temperature is 150 degreeC or more, it is more preferable. On the other hand, since the magnetic layer may be excessively heated and deformed, the temperature is preferably 700 ° C. or lower.

When the magnetic recording medium is a magnetic recording medium in the horizontal direction, it is difficult to perform saturation recording on a magnetic recording medium suitable for high density recording with coercive force, and to form a magnetic pattern having high magnetic field strength by the conventional magnetic printing method. Is difficult. Also, the half value width of the reproduction signals is increased. According to the method of the present invention, a desired magnetic pattern can be formed even in a horizontal recording medium suitable for high density recording. In particular, when the saturation magnetization of the magnetic layer is 50 emu / cc or more, the influence of the diamagnetic system becomes large. Therefore, the application of the present invention provides a great effect.

When more than 100 emu / cc, a higher effect can be obtained. However, when the saturation magnetization is excessively large, the magnetic pattern is difficult to form. Therefore, 500 emu / cc or less is preferable.

When the magnetic recording medium is a vertical magnetic recording medium, the magnetic pattern is relatively large, and the unit volume of the magnetic region is large, the saturation magnetization tends to be large, and the reverse magnetization tends to occur due to the magnetic erasing effect. This produces noise and lowers the half value width. However, the present invention makes it possible to preferably record on such a medium by using a combination of a soft magnetic layer and a lower layer.

Two or more recording layers may be formed to increase the recording capacity. In this case, it is preferable to form another layer therebetween.

In the present invention, a protective layer is formed on the magnetic layer. In particular, the outermost circumferential surface of the medium is covered with a hard protective layer that can avoid damaging the magnetic layer by collision of the magnetic head or depositing dust on the layer opposite the mask. In the application of the method of forming a magnetic pattern using a mask according to the present invention, the protective layer protects the medium from contact of the mask.

In addition, the protective layer is essential to prevent oxidation of the heated magnetic layer in the present invention. The magnetic layer is usually easily oxidized and the oxidation is accelerated by heating. In the present invention, since the magnetic layer is locally heated by the energy beams, it is necessary to form a protective layer on the magnetic layer in advance to prevent oxidation.

When a plurality of magnetic layers are formed, the protective layer should be formed on the magnetic layer formed near the front surface. The protective layer may be formed directly on the magnetic layer, or a layer having another function may be inserted as necessary.

Some of the energy beams are absorbed by the protective layer so that the magnetic layer is locally heated by thermal conduction. When the protective layer is too thick, the magnetic pattern may become obscure by laterally conducting heat. Therefore, it is preferable that the thickness of the said protective layer is thin. In addition, it is desirable to reduce the thickness in order to reduce the distance between the magnetic layer and the head at the time of reproducing data. Therefore, the thickness is preferably 50 nm or less, more preferably 30 nm or less, even more preferably 20 nm or less. However, the thickness is preferably 0.1 nm or more, more preferably 1 nm or more in order to obtain sufficient durability.

The protective layer material must be resistant to oxidation and hard. For the protective layer, a layer made of a carbon material such as carbon, hydrogenated carbon, carbon nitride, amorphous carbon, SiC, or the like or a hard material such as SiO ₂ , Zr ₂ O ₃ , SiN, TiN, or the like may be used. In addition, the material for the protective layer may have magnetic properties.

In magnetic disks, in order to reach the limit between the head and the magnetic layer, it is necessary to form a very hard protective layer thinly. Therefore, from the viewpoint of impact resistance and lubrication properties, a protective layer made of a carbon material, in particular diamond-based carbon, is preferable. This serves to prevent damage of the magnetic layer by the energy beams and is very resistant to damage of the magnetic layer generated by the magnetic head. The magnetic pattern forming method of the present invention is applicable to an opaque protective layer such as a carbonaceous protective layer.

In addition, the protective layer may be formed of two or more layers. When a layer containing Cr as a main component is formed directly on the magnetic layer as a protective layer, it has a remarkable effect in preventing oxygen permeability to the magnetic layer.

A lubrication layer is formed on the protective layer to prevent damage to the medium, caused by contact with the medium to a mask or magnetic head. As the lubricating layer used as the lubricating layer, fluorine type lubricating layer, hydrocarbon type lubricating layer and mixtures of these materials are mentioned. The lubricating layer may be coated by conventional methods such as precipitation method, spin coating and the like. That is, the lubricating layer can be formed by the vapor deposition method. The thickness of the lubricating layer is preferably made thin so as not to interfere with the formation of the magnetic pattern, the thickness is preferably 10 nm or less, more preferably 4 nm or less. In addition, the thickness is preferably 0.5 nm or more, and more preferably 1 nm or more, in order to obtain sufficient lubrication performance.

In the case of irradiating energy beams from a position on the lubrication layer, the lubrication layer may be supplied again on the lubrication layer in consideration of damage (decomposition or polymerization) of the lubrication layer.

The surface roughness Ra of the medium after magnetic pattern formation is preferably kept below 3 nm so as not to lower the safety against the movement of the flying / contacting head. The surface roughness Ra of the medium is about the roughness of the surface of the medium having no lubricating layer. The value of the surface roughness is obtained by measuring a measurement length of 400 μm using a contact finger type surface roughness meter and by calculating a value obtained according to JIS B0601. The value is preferably 1.5 nm or less.

Preferably, after formation of the magnetic pattern, the surface relief Wa of the medium is maintained at 5 nm or less. Wa is the amount of undulation on the surface of the medium without a lubricating layer, which is obtained by measuring the measured length of 2 mm using the contact finger surface roughness meter and by calculating the value obtained according to the calculation of Ra. The value is preferably 3 nm or less.

Various methods can be considered as the layer forming method for forming each layer of the magnetic recording medium. For example, physical vapor deposition methods such as DC (magnetron) sputtering method, high frequency (magnetron) sputtering method, ECR sputtering method, vacuum deposition method and the like are mentioned.

As conditions for forming the layers, depending on the characteristics of the medium to be obtained, the degree of ultimate vacuum, the method for heating the substrate, the substrate temperature, the sputtering gas pressure, the bias voltage, and the like are appropriately determined. For example, in forming a layer by sputtering, an extreme process degree of 5 x 10 ^-6 Torr or less, a substrate temperature of room temperature to 400 ° C, a sputtering pressure of 1 x 10 ^-3 to 20 x 10 ^-3 Torr, and 0 A bias voltage of from -500 volts is usually preferred.

When the substrate is heated, the substrate can be heated before the underlayer is formed. When a transparent substrate having a low heat absorption coefficient is used, a seed layer containing Cr as a main component or an underlayer having a B2 crystal structure for increasing the heat absorption coefficient can be formed, after which the substrate is heated and then A recording layer or the like can be formed thereon.

When the recording layer is a rare earth magnetic layer, it is preferable to prevent corrosion and oxidation to the layer by the following method. That is, a coated mask is applied to the innermost peripheral portion and the outermost peripheral portion for the disk, and a layer is formed by forming the recording layer, and the coated mask is removed before forming the protective layer, and the protection There is a method in which the layer is formed to cover the entire recording layer. When the protective layer includes bilayers, the steps until the formation of the recording layer and the first protective layer are performed using a coated mask, and the coated mask is removed before the second protective layer is formed to form the first protective layer. 2 The entire recording layer is covered with a protective layer.

Next, a magnetic pattern forming apparatus according to the present invention is described.

The magnetic pattern forming apparatus of the present invention utilizes a magnetic layer formed on a substrate by using a step of irradiating energy beams to the magnetic recording medium to locally heat the magnetic layer and applying an external magnetic field to the magnetic layer. Apparatus for forming a magnetic pattern on a magnetic recording medium having a device, wherein the apparatus comprises: medium holding means for holding a magnetic recording medium, external magnetic field applying means for applying an external magnetic field to the magnetic recording medium, and radiating energy beams An energy beam source for projecting, projection means for projecting and irradiating energy beams from the energy beam source to the magnetic recording medium and a magnetic recording pattern and energy beam source for changing the intensity distribution of the energy beams in response to a magnetic pattern to be formed. It includes a mask located in between.

In the above-described apparatus, the magnetic pattern is formed by jointly using means for locally heating the magnetic layer and external magnetic field applying means for applying an external magnetic field. Thus, a magnetic pattern can be formed without using a strong external magnetic field applying means as in the prior art. In addition, regions other than the heating region of the magnetic layer are not magnetized even if a magnetic field is applied to the region, so the magnetic regions are formed only in the heated region. Therefore, it is possible to form a pattern in which the transition of the magnetic regions is clear, the magnetic transition width is small, the magnetic transition of the magnetic regions is very rapid, and the quality of the output signals is high. By selecting the conditions, the magnetic transition width can be formed to 1 μm or less.

According to this technique, since the medium does not need to be brought into close contact with the master disk by vacuum suction as in the conventional magnetic printing technique, a simple medium holding means can be used. Further, in the prior art, the attach / removal process had to be repeated for the mask every time the medium was replaced. However, according to this technique, once the mask is placed, there is no need to remove it. In addition, when the mask is positioned away from the disk, it is possible to easily manipulate the placement and removal of the disk or mask. In addition, since energy beams are used for local heating, control of power and the location to be heated is facilitated. Local heating of the recording layer surface is also sufficient as an energy beam source. However, a laser light source is preferred, since it is possible to prevent the energy beams from being irradiated on unnecessary portions.

In order to obtain a sharp magnetic transition width, a pulsed laser is preferred since there is a large temperature difference between the energy beam irradiation time and the unirradiated time and heat storage hardly occurs. Although continuous lasers can be converted to pulsed lasers by optical means, it is preferred to use pulsed lasers. The pulsed laser light source emits intermittent lasers in the form of pulses. It can irradiate such lasers with high power peak values in a very short time, so no heat storage occurs.

When a mask, for example a photomask, which optionally has a transfer portion for transferring energy beams is used, it is easy to manufacture and high precision finishing can be easily performed. Thus, a very precise mask can be formed, and a much more precise magnetic pattern can be formed.

In a preferred embodiment, an intensity distribution equalization means for equalizing the intensity distribution of the energy beams radiated from said energy beam source is disposed between said energy beam source and said projection means, and said mask comprises an intensity distribution equalization means and a magnetic recording medium. Is placed in between.

According to such an embodiment, the intensity distribution equalization means equalizes the intensity distribution of the energy beams in advance, so that the heat distribution in the irradiated area can be suppressed to be small, and the distribution of the magnetic field intensity of the magnetic pattern can be suppressed to be small. Therefore, in reading the signal strength by using the magnetic head, it is possible to form a magnetic pattern having a very uniform signal strength.

As means of equalizing the intensity distribution, a homogenizer using a prism array or a fly-eye lens, a shading substrate, a slit or the like is mentioned as an example.

Preferably, the intensity distribution equalization means has such a function that the energy beams are divided into a plurality of parts, and the divided parts are superimposed so that the energy beams can be effectively used. In the present invention, it is preferable to heat the magnetic layer by irradiating high intensity energy beams within a short time. For this purpose, the energy of the energy beams must be used effectively.

The medium holding means for the magnetic recording medium includes a mechanism for supporting the medium, in particular the spindle, the guide, the press substrate, the spacer and the turntable. Materials used in the holding means are those materials capable of holding the magnetic recording medium in terms of strength. However, materials that are thermally stable in dimension are desirable because they are irradiated with energy beams. Metals, alloys, resins, ceramics or glass can be used. Among them, metals or alloys are preferred because they can diffuse heat generated by the energy beams in a short time. In particular, metals or alloys having large heat spreading properties are more preferred.

Next, it will be described in more detail with reference to the drawings. A magnetic pattern is formed by applying an external magnetic field to uniformly magnetize the magnetic layer, and then an external magnetic field having an opposite direction is applied while locally heating the magnetic layer.

3 and 4 show examples of the method of applying the magnetic field and the disk holding means of the magnetic pattern forming apparatus according to the present invention.

As shown in Fig. 3 (a) in cross section, a magnetic disk 1 on which a magnetic pattern is to be formed is disposed on a turntable 3 fixed coaxially with a rotatable spindle 2, the magnetic disk being vacuum grooved. It is fixed to the turntable 3 by (7). The magnetic disk 1 has a hard substrate 21 and magnetic layers 22a and 22b sandwiching the substrate 21 therebetween.

On the disk 1, a first magnetic field applying means 4 having a yoke 5 and a permanent magnet 6 is arranged. Fig. 3 (b) is a view seen from the arrow direction of Fig. 3 (a). The first magnetic field applying means 4 has a radially extending shape of the disk 1, which is a pair of permanent magnets such as NdFe magnets fixed on the yoke 5 using magnetic poles opposite each other. By having (6a, 6b), a magnetic field is generated between the N pole of the permanent magnet 6a and the S pole of the permanent magnet 6b. By generating a magnetic field larger than the coercive force of the disk 1, the magnetic layer 22a on the upper surface of the magnetic disk 1 is magnetized in the circumferential direction, which is the horizontal direction of the disk.

When the spindle 2 is rotated in such a state that the first magnetic field applying means 4 is fixed, the magnetic disk is rotated in the direction of the arrow, and the magnetic field is applied throughout the magnetic layer 22a so that one direction Is magnetized to After that, the first magnetic field applying means 4 is moved.

Thereafter, while heating the magnetic disk 1 locally, an external magnetic field having a magnetic direction opposite to the magnetic disk 1 is applied. As shown in the cross-sectional view of FIG. 4, a second magnetic field applying means 8 having a yoke 9 and a permanent magnet 10 is arranged on the other side of the disk 1. The direction of the magnetic field generated from the second magnetic field applying means is opposite to the direction of the first magnetic field applying means 10, and the intensity of the magnetic force from the second magnetic field applying means 8 is the coercive force of the disk 1. Is less than The structure and shape of the second magnetic field applying means 8 other than those described above may be the same as the structure and shape of the first magnetic field applying means 4.

The laser 11 emitted from a light source (not shown) reaches the projection lens 15 which reduces the laser beam spot to a predetermined size and is introduced into the photomask 12. The photomask 12 comprises a layer 14 opaque to the wavelength of the laser—a transparent substrate and a magnetic pattern to be formed. By having the laser 11 transmitted only through the transparent portion, the intensity distribution (density) is changed in accordance with the magnetic pattern to produce a partially patterned laser, which is projected onto the magnetic disk 1. do.

The photomask 12 is sputtered on a substrate made of a material such as quartz glass, soda lime glass or the like, sputtered by a metal such as Cr and opaque to energy beams, and coating a photoresist thereon, By selectively etching the opaque material on the photoresist and energy beams, the photomask 12 can be created, and transparent and non-transmissive portions can be formed as desired.

The irradiation area is heated, and the magnetic layer 22a is heated to a level close to the self-erasing temperature. At the same time, the external magnetic field is applied by the second external magnetic field applying means 8 which is smaller in the coercive force than the magnetic layer 22a of the magnetic disk 1. Thus, only the heated portion is magnetized in the direction of the external magnetic field. Thereafter, the irradiation of the laser is stopped, the heated portion can be cooled to room temperature, and stable magnetization can be obtained. Since the second external magnetic field is opposite to the direction of the first external magnetic field previously used to uniformize the magnetization, a magnetic pattern can be formed in the magnetic layer 22a as described above.

When a magnetic pattern is formed in another region of the magnetic layer 22a, while the second magnetic field application stage 8 remains stationary, the spindle (to rotate the magnetic disk 1 by a predetermined angle) 2) is rotated and the photomask 12 is moved to a predetermined position. Thereafter, magnetic application and heating are simultaneously performed.

5 shows an example of the structure of an optical system for irradiating a laser used in the present invention. The pulsed laser 11 emitted by the pulsed laser light source 41 passes through a programmable shutter 42 frame having only the desired number of pulses. The pulsed laser light source 41 may be, for example, a fourth harmonic YAG-Q-switched laser or excimer laser.

If the laser 11 selected by the programmable shutter 42 is introduced into the attenuator 43, converted to have a predetermined power, and then it is desired to increase the reduction rate for the projection of the mask, Before forming the image, it is incident to the beam expander 45 which is used to increase the beam diameter once.

Then, before reaching the projection lens 15, the laser 11 divides the prism array 46 into three parts and the prism array 47 to divide the long axis part into seven parts. Pass). The prism arrays 46 and 47 function to ss the laser into predetermined portions, overlap the divided portions, and equalize the intensity distribution of the energy beams. These members are sometimes called homogenizers.

Also, if necessary, the laser 11 is passed through the shading substrate 49 so that the laser 11 has a predetermined beam shape. The intensity distribution of the laser is changed by the photomask 12 in accordance with the magnetic pattern, after which the laser is projected onto the surface of the disk 1, and the magnetic layer 22a is heated. The shading substrate may be one that does not transmit the wavelength of the energy beams used, ie it reflects or absorbs the energy beams. However, if the shading substrate absorbs the heated energy beams, the generated heat easily affects the magnetic pattern. Therefore, it is preferable to use a material having high thermal conductivity and high reflectivity. For example, metal substrates such as Cr, Al or Fe are preferred.

Cylindrical or condenser lenses can be used in place of homogenizers to even out the intensity distribution of the energy beams. They can also be used together. Alternatively, another lens can be inserted if necessary. Alternatively, the slits can be used to remove energy portions with low density and to have only energy portions of good distribution.

As described above, the structure of the optical systems used in the present invention and the order of the systems can be changed as necessary.

The external magnetic field can be applied by the second external magnetic field applying means from either surface side of the disk. However, as shown in Fig. 4, the second external magnetic field applying means is disposed at a position opposite to the disk surface to which the laser is irradiated. Therefore, it does not block the laser. However, the external magnetic field applying means may be arranged on the surface side to which the laser is irradiated so as not to block the laser. In the case where a strong magnetic field is desired, the application means is preferably arranged on each side of the disk surface.

Further, the projection means is preferably imaging means for forming a reduced image on the surface of the medium by irradiating energy beams whose intensity distribution is changed, wherein the imaging means is disposed between the mask and the magnetic recording medium.

The embodiment shown in FIG. 7 is described in detail, wherein like reference numerals denote the same or corresponding parts.

The magnetic disk 1 is previously uniformly magnetized by the apparatus shown in FIG. While locally heating the disk 1 an external magnetic field having an opposite direction is applied. As shown in the cross-sectional view of FIG. 7, the second magnetic field applying means 8 with the yoke 9 and the permanent magnet 10 is arranged at a position opposite to the other surface of the disk 1. The direction of the magnetic field generated by the second magnetic field applying means 8 is opposite to the direction of the first magnetic field applying means, and the strength of the magnetic field is smaller than the coercive force of the disk 1. The structure and shape of the second magnetic field applying means 8 other than those described above may be the same as the structure and shape of the first magnetic field applying means 4.

The pulsed laser 11 emitted by a light source (not shown) is introduced into the photomask 12 through a condenser lens. The photomask 12 is formed on the substrate 13 and the substrate 13 transparent to the laser wavelength, and has an opaque layer 14 opaque to the magnetic pattern to be formed. By passing the laser 11 only through the transparent portion, the intensity distribution is changed in accordance with the magnetic pattern to provide a patterned laser in space. The photomask 12 may be such a conventional photomask.

The laser 11 reduces the laser beam spot to reach the imaging lens 15 having a predetermined size, and the density of the laser similar to the pattern formed on the photomask 12 is reduced on the magnetic disk 1. It is formed as an image. The portion where the reduced image is formed is heated, and the magnet 22a is heated to a level close to the demagnetization temperature. At the same time, an external magnetic field is applied by the second external magnetic field applying means 8, and the intensity of the external magnetic field becomes smaller than the coercive force of the magnetic layer 22a of the magnetic disk 1. Thus, only the heated portion is magnetized in the direction of the external magnetic field. Thereafter, the irradiation of the laser is stopped, and the heated portion is cooled to room temperature, whereby the magnetization becomes stable. Since the direction of the second external magnetic field is opposite to the direction of the first external magnetic field previously used to uniformize magnetization, a magnetic pattern is formed of the magnetic layer 22a.

When a magnetic pattern is formed in another region of the magnetic layer 22a, the spindle 2 allows the magnetic disk 1 to rotate by a predetermined angle while keeping the second magnetic field applying means 8 stationary. Rotate Thereafter, it is heated and a magnetic field is applied.

)은 촬상 렌즈의 개구수 NA 와 사용된 에너지빔들의 파장 λ에 의해 결정되고,

= 1.22 ×(λ/NA)의 관계가 성립된다. 즉, 핑거(finger) 패턴이 자기 기록 매체내에 형성될 때, λ를 감소시키거나 NA 를 증가시킬 필요가 있다.Minimum beam diameter reduced by the imaging lens (

) Is determined by the numerical aperture NA of the imaging lens and the wavelength λ of the energy beams used,

A relationship of = 1.22 × (λ / NA) is established. That is, when a finger pattern is formed in the magnetic recording medium, it is necessary to decrease λ or increase NA.

When the condenser lens is positioned in front of the mask, the intensity distribution of the energy beams can be made uniform, and the energy beams can be effectively collected by the imaging lens. When the laser beams are reduced by the condenser lens, the NA of the imaging lens is determined in consideration of the NA of the condenser lens.

8 shows an example of the structure of an optical system for irradiating a laser used in the present invention, wherein like reference numerals denote the same or corresponding portions.

The pulsed laser 11 radiated from the pulsed laser light source 41 is passed through a programmable shutter 42 that can only have a predetermined number of laser pulses from the pulsed laser light source to the laser. As the pulse laser light source 41, for example, a fourth harmonic YAG-Q-switched laser or excimer laser can be used.

The laser 11 selected in the programmable shutter 42 is sent to an attenuator 43 which converts the power of the laser so as to have a predetermined power. Thereafter, the laser reaches the photomask 12 through the condenser lens 44. The condenser lens 44 is typically equipped with an aspheric lens and a plano-convex lens 44b, which equalizes the intensity distribution of energy on the mask surface and additionally captures the imaging lens 15. This function effectively introduces the energy beam magnetic flux.

Thereafter, the intensity distribution of the laser 11 is changed according to the magnetic pattern by the photomask 12 and passed through the imaging lens 15 so that a reduced image is formed on the surface of the disk 1. do.

Figure 9 shows another example of the structure of an optical system for irradiating a laser used in the present invention, wherein like reference numerals denote the same or corresponding portions.

The pulsed laser 11 emitted from the pulsed laser light source 41 reaches the beam expander 45 through the programmable shutter 42 and the attenuator 43. In such cases where the reduction ratio for the projection of the mask is increased, the beam expander 45 is used to increase the beam diameter once before image formation.

Thereafter, the laser 11 passes through the condenser lens 44 and then through the imaging lens 15 so that the intensity distribution of the laser reaches the photomask 12 which is changed in accordance with the magnetic pattern, thereby reducing it. An image is formed on the surface of the disc 1.

To equalize the intensity distribution of energy, a homogenizer can be used in place of the condenser lens. Alternatively, the condenser lens and homogenizer may be used together.

Or, if such equalization means are not used, slits or the like can be used to shield the weak energy portion and to take only the energy portion with a good distribution of energy.

Further, the energy beams can be shaped into the desired beam shape by using a shading substrate. 10 is a diagram illustrating an example of the shading substrate 49. The shading substrate 49 has a substrate 51 which prevents the laser 11 from passing through the shading substrate, and a laser transmitting portion 52 having a shape corresponding to the desired beam shape is formed. In Fig. 10, a substantially fan shape is shown as an example. However, another shape may be used, such as a substantially rectangular shape.

The shielding substrate prevents the laser from irradiating into an undesired area or re-radiates the laser into an area where a magnetic pattern has already been formed. However, the shielding substrate is provided as necessary. Although the location to be placed is not limited, it is desirable to place it immediately before or just after the mask.

As described above, the structure and order of the optical system used in the present invention can be changed upon request.

The second external magnetic field applying means may be arranged on either side with respect to the disk surface. However, in the above embodiment, the second external magnetic field applying means is located on the side of the disk surface on which the laser irradiation is performed, so that there is no possibility of blocking the laser. However, the external magnetic field applying means may be arranged on the surface side to which the laser is irradiated so as not to block the laser. In the case where a strong magnetic field is required, the applying means is preferably arranged on either side of the disk surface.

Next, a method for producing a magnetic recording medium according to the present invention will be described.

The method of manufacturing the magnetic recording medium of the present invention includes forming a magnetic layer and a protective layer on a substrate, forming a lubricating layer, and forming the magnetic pattern described above. Thus, fine patterns can be formed accurately and easily in a short time. In the case where the surface roughness Ra is 3 nm or less after the formation of the magnetic pattern, since there are almost no protrusions and recesses, there is no possibility that the movement of the flying / contacting head becomes unstable. Formation of the magnetic layer, the protective layer and the lubricating layer may be performed according to conventional methods. For example, the magnetic layer and the protective layer can be formed by sputtering or CVD, and the lubricating layer can be formed by precipitation coating.

Magnetic pattern formation methods can be used to record data. However, since it allows very accurate control such as position control or synchronous control with respect to the head on which the magnetic recording medium should be kept stable, it is preferably used to form a control pattern for controlling the recording / reproducing magnetic head. In the manufacturing method of the present invention, the lubricating layer may be formed after the formation of the magnetic pattern, more preferably before and after the formation of the pattern.

When forming a magnetic pattern by combining the heating of the local area and the application of an external magnetic field, a partial reduction of the lubricating layer on the magnetic recording medium can occur by heating. In addition, contact of the lubricating layer with respect to the mask occurs, reducing the lubricating layer.

Reduction of the lubrication layer reduces the durability and impact resistance to the magnetic head. Therefore, after the magnetic pattern is formed by combining local heating and application of an external magnetic field, to provide a sufficient layer thickness, it is preferable that an additional lubrication layer is formed, thereby achieving durability and high impact resistance to the magnetic head. Can be.

In this case, two embodiments can be considered.

Example A: A lubrication layer is not formed before the formation of the magnetic layer, and the lubrication layer is formed after the formation of the magnetic pattern.

Example B: A first lubrication layer is formed before the formation of the magnetic pattern, and a second lubrication layer is formed after the formation of the magnetic pattern.

Each of the above embodiments is described in detail.

(1) Example A

For example, a magnetic disk is manufactured by forming a NiAl lower layer, a CrMo lower layer, a Co type alloy magnetic layer, a diamond type carbon protective layer, etc. by sputtering on a glass substrate or an aluminum alloy substrate.

Thereafter, the inspection (proof) of the defect is performed using, for example, a non-contact optical surface testing apparatus. The lubrication layer is unnecessary since high speed testing can be performed and the magnetic layer is not used.

The magnetic pattern is formed according to the method described above. For example, a strong external magnetic field is applied to the magnetic disk to uniformly magnetize the magnetic layer in the desired direction before heating, after which the desired portion is heated to a level close to the Curie temperature and at the same time the portion is reversed. The branches are magnetized by applying an external magnetic field so that a magnetic pattern can be obtained. Thereafter, the lubricating layer is formed by coating the lubricating layer.

In Example A, since no lubrication layer is formed before the formation of the magnetic pattern, there is no risk of scattering, diffraction, or interference of energy beams due to the presence of the lubrication layer with respect to heating. In addition, since the magnetic recording medium can be in close contact with the mask, deposition of the lubrication layer on the mask can be avoided. Therefore, diffraction of the energy beams can be minimized, and a high signal output and a cleanly shaped magnetic pattern can be accurately formed.

In addition, since a lubrication layer having a sufficient thickness can be provided after the formation of the pattern, the durability and impact resistance of the magnetic head become high.

In the final stage of manufacture, the magnetic disk is typically burnishing using a burnishing head so that protrusions having a predetermined or greater height are removed. Thereafter, the presence or absence of the protrusions is inspected, defects are inspected (identified), and the position and number of defects are detected by recording / reproducing a specific pattern using a magnetic head.

This embodiment is preferably applied to cases in which recording / reproducing of data is performed by the magnetic head before the formation of the magnetic pattern, and testing and evaluation are not performed. For example, it is possible to perform a test without the use of a magnetic head, such as a non-contact optical surface testing apparatus, prior to the formation of the magnetic pattern. The test by the magnetic head may be performed after the formation of the pattern and after the lubrication layer is formed. Alternatively, the case where the test by the magnetic head is not performed at all is considered.

Typically, the formation of the lubrication layer is carried out by coating the lubrication layer by, for example, spin coating, full-up coating, spray coating or by an optical coating step. Pull-up coating methods are suitable when trying to uniformly form a lubricating layer on multiple media in a short time.

The lubricating layer preferably has an ester bond and includes perfluoropolyether, dialkylamide carboxylate, perchlorinated polyether, stearic acid, stearate, phosphate ester and the like. Ester bonds may be present at any position in the molecules. However, the lubricating layer has functional groups of ester bonds at the terminals, the movable portions in the molecules are extended, and lubricating properties can be easily obtained.

In particular, perfluoropolyethers with -C _a F _2a O- units in which a is an integer of 1 to 4 in the main chain and functional groups of ester bonds at the terminals are preferred. In particular, perfluoroethers represented by the following formulas are present.

RO- (A ¹ -OA ² -O) _X -R

Wherein each terminal of A ¹ and A ² is CF ₂ and / or C ₂ F ₄ ; The ratio of C ₂ F ₄ to CF _{2 as} A ¹ and A ^{2 (} CF ₂ / C ₂ F _{4 )} is 5/1 to 1/5; X is 10 to 500, and R represents an alkyl group or fluorinated alkyl group having 1 to 20 carbon atoms containing a hetero atom.

For example, Fomblin-Z-DOL manufactured by Ausimont Company has CF ₂ CF ₂ O having an ester group -COOR (R represents an alkyl group which can be replaced by fluorine) at both terminals and having a linear chain structure; Copolymer of CF ₂ O. In addition, the Demnum type (SP or SY) produced by Daikin Company is a homopolymer of hexafluoropropylene oxide having ester group -COOR at one terminal (where R represents an alkyl group which can be replaced by fluorine).

The average molecular weight number of the lubricating layer is preferably 100 to 10,000, more preferably 2,000 to 6,000. In the case where the molecular weight is small, the vapor pressure becomes high, and steam is gradually generated after coating. As a result, the originally expected layer thickness changes over time. In contrast, when the molecular weight is large, there are cases where the viscosity is increased so that the desired lubricating properties cannot be obtained.

Preferably, Fomblin-Z-DOL (trade name) or Fomblin-Z-Tetraol (trade name) manufactured by Ausimont Company may be used.

Solvents for dissolving such materials may be flon type, alcohol type, hydrocarbon type, ketone type, ether type, fluorine type, aromatic type and the like.

It is preferable to perform a heat treatment after the formation of the lubrication layer in order to improve the chemical bonding of the lubrication layer and the medium.

The heating temperature is usually at least 50 ° C. However, the temperature is suitably selected in a temperature range lower than the decomposition temperature of the lubricating layer. The heating temperature is 100 degrees C or less normally.

The thickness of the layer formed by coating with a lubricating layer is preferably 10 nm or less. If the thickness is excessively large, the expected lubrication characteristics cannot be obtained, and an excessive amount of the lubricating layer is moved to the outer portion by the rotation of the disk, so that the layer thickness distribution between the inner portion and the outer portion is likely to occur. However, if the thickness is very small, the expected lubrication characteristics cannot be obtained. Therefore, the thickness is preferably 0.5 nm or more, more preferably 1 nm or more, even more preferably 1.5 nm or more.

(2) Example B

The magnetic disk is provided on a substrate such as, for example, a glass substrate or an aluminum alloy, by sputtering to provide a NiAl underlayer, a CrMo underlayer, a Co alloy alloy layer, a diamond-based carbon protective layer, and the like to form a first lubrication layer thereon. Is manufactured by.

Thereafter, the magnetic disk is burnishing using a burnishing head to remove protrusions having a predetermined height or a higher height. The presence or absence of the protrusions is checked. In addition, inspection (proof) of defects is performed, and the position and number of defects are detected by recording or reproducing a specific pattern using a magnetic head.

Thereafter, the magnetic pattern is formed in the same manner as in Example A.

According to Example B, the first lubrication layer is formed in advance, so that the magnetic head can be used to record or reproduce data before the formation of the magnetic pattern as well as various tests and evaluations. For example, the magnetic head can be used to check the location and number of defects by recording or playing back a specific pattern. Since the specific pattern overlaps the desired magnetic pattern, the test is performed before forming the magnetic pattern without removing the specific pattern used for the test. The presence of protrusions or dust causes irregular reflections of the energy beams, disturbing the magnetic pattern. Therefore, it is desirable to carry out the inspection in advance to select projections or dust free media. In addition, since the magnetic pattern is formed in the media that passed the test, unnecessary steps can be reduced, which is advantageous in terms of cost.

In addition, since a stable bonding of the lubricating layer can be easily obtained, the lubricating layer is formed as soon as possible after the formation of the protective layer.

Typically, the lubrication layer has a fixed portion and a non-fixed portion. A lubrication layer on the magnetic recording medium (i.e., typically a protective layer formed on the outermost plane of the medium) is bonded and fixed to the surface of the medium. That is, the lubricating layer is chemically and firmly bonded to the protective layer or the magnetic layer. In addition, there is an unlubricated and free lubrication layer. In order to ensure a magnetic recording medium of sufficient durability, a fixed portion and an unfixed portion need to be appropriately present.

According to the study by the inventors of this specification, it is assumed that the part of the lubricating layer where the loss of weight by heating occurs is mainly an unfixed portion, and there is little weight loss of the fixed portion.

Therefore, it is ideal that the first lubrication layer mainly includes a fixed portion that is hardly volatile even when heated. For this purpose, the first lubrication layer should be as thin as possible, which is preferably 2.0 nm or less. The thin layer thickness minimizes scattering, diffraction and interference of the energy beams. In addition, since the unfixed portion of the lubrication layer is small and the amount of steam is small even when the local region of the medium is heated, the contact of the first lubrication layer to the mask can be prevented. Using such a method, a magnetic pattern with a clean shape and high signal output capability can be formed with excellent precision. As for thickness, 1.0 or less are more preferable.

On the other hand, it is necessary to thicken the lubricating layer in order to maintain the impact resistance and durability to the magnetic head for a long time. For example, the thickness is preferably 1.5 nm or more. However, for testing or evaluation only, the lubricating layer must be sufficiently durable even if its thickness is thin. Therefore, the thickness of the first lubricating layer is preferably 0.1 nm or more, more preferably 0.5 nm or more, in order to withstand recording or reproduction by the magnetic head in a short time.

Alternatively, after the magnetic recording medium has been tested using the magnetic head, the first lubrication layer can be removed before the formation of the magnetic pattern. In this case, the energy beams used for heating in the formation of the magnetic pattern are blocked by the lubrication layer, and by the space corresponding to the thickness of the lubrication layer when the lubrication layer is present between the mask and the magnetic recording medium, Such problems that the precision of the magnetic pattern is degraded by the deflection of the energy beams upon irradiation of the energy beams through the mask can be reduced. In addition, since the evaporation of the lubricating layer by heating can be minimized, there is no possibility of contamination of the mask. For example, the lubrication layer forming the first lubrication layer can be removed by being cleaned by soluble detergent.

Thereafter, a second lubrication layer having a sufficient thickness can be provided after formation of the pattern to compensate for the reduction of the lubrication layer in the heating step or to reconstruct the removed lubrication layer, giving the magnetic head high impact resistance and durability. do. Since the second lubrication layer compensates for the free portion of the lubrication layer, the thickness can be thin compared to the case where the lubrication layer is formed only once. If the lubrication layer is too thick, problems may arise that the head adheres to the medium and is difficult to fall off.

The lubricating layer may be conventionally formed by coating the lubricating layer, for example by spin coating, pull-up coating, spray coating, or by another suitable coating step. Among them, a pull-up coating method is suitable for uniformly forming a lubricating layer on many media in a short time. However, in order to form a thin film, the spin coating method in which the lubricating layer is scattered by the centrifugal force is also suitable.

Moreover, it is preferable to make the density | concentration of the lubrication layer at the time of formation of a 2nd lubrication layer lower than the density | concentration of the lubrication layer at the time of formation of a 1st lubrication layer. It is preferably about 50% or less of the concentration of the lubrication layer initially applied, more preferably about 10 to 20% of the concentration of the lubrication layer initially applied.

The lubrication layer for forming the second lubrication layer may be different from the lubrication layer for forming the first lubrication layer. However, it is preferred that the same lubrication layer be used to simplify the above steps. If the same lubrication layer is used for the first and second lubrication layers, the lubrication layers as a whole constitute a single layer.

Applicable lubricating layers and solvents may be the same as those used in Example A.

The layer thickness of the fixed part chemically bonded to the medium varies somewhat depending on the type of lubricating layer. The thickness is in the range of about 0.5 to 1.0 nm. Lubricating layers with polar atom groups at the terminals are typically thick. For example, the lubrication layer of Fomblin-Z-DOL ™ manufactured by Ausimont Company does not have a polar atom group at the terminals. Thus, the fixed portion is relatively thin. Such parts with high molecular weights exhibit high viscosity and weak flow properties, so that the parts are difficult to flow and are prone to thickening. The DOL series described above tends to increase in thickness as the molecular weight becomes larger.

Alternatively, in order to precisely control the layer thickness of the lubrication layer, the lubrication layer may be removed by washing with a suitable solvent before the formation of the magnetic pattern, after which the lubrication layer may be coated again after the formation of the magnetic pattern.

The cleaning solvent may be one having a non-corrosive property in the medium and a high solubility in the lubricating layer, such as a flon type, alcohol type, hydrocarbon type, ketone type, ether type, fluorine type, aromatic type and the like.

It is preferable to perform a heat treatment after the formation of the lubrication layer to improve the chemical bonding of the lubrication layer to the medium. The temperature of heating is 50 degreeC or more. However, the temperature may be appropriately selected to a temperature range lower than the decomposition temperature of the lubricating layer. Usually, the temperature is 100 degrees C or less.

The total layer thickness of the lubricating layer is preferably 10 nm or less. If the thickness is too large, the expected lubrication characteristics cannot be obtained, and the rotation of the disk causes the excessive amount of lubrication layer to move to the outer part, so that the layer thickness distribution between the inner and outer parts is likely to occur. However, even if the thickness is too small, the expected lubrication characteristics cannot be obtained. Therefore, the thickness is preferably 0.5 nm or more, more preferably 1 nm or more, even more preferably 1.5 nm or more.

Next, a magnetic recording apparatus according to the present invention is described.

The magnetic recording apparatus of the present invention includes a magnetic recording medium in which a magnetic pattern is formed according to the above-described magnetic pattern forming method, drive means for driving the magnetic recording medium in the recording direction, a magnetic head having a recording portion and a reproduction portion, and a magnetic recording medium. Means for moving the magnetic head relative to the magnetic head and recording / reproducing signal processing means for supplying a recording signal to the magnetic head and receiving a reproduction signal from the magnetic head. As a magnetic head, a flying / contacting magnetic head is commonly used to perform high density recording.

Since a magnetic recording medium on which a magnetic pattern such as a fine and very precise servo pattern is formed is used, such a magnetic recording apparatus can record with high density. In addition, the use of a defective or less defective medium reduces errors in recording.

Precise servo signals can be easily obtained using a magnetic recording device, where after the magnetic recording medium is assembled in the magnetic recording device, the above-described magnetic pattern is reproduced by the magnetic head to obtain the signals, and Based servo burst signals are recorded by the magnetic head.

Further, after the servo burst signals are recorded by the magnetic head, the signals recorded in the magnetic pattern formed by the present invention are preferably present in an area which is not used as the data area of the user. In this case, the magnetic head can be easily moved to the desired position even when the positional deviation of the magnetic head is caused by any disturbance. Thus, such a magnetic recording apparatus having signals generated by both recording methods is very reliable.

A magnetic disk device is described as a typical example of the magnetic recording device.

Magnetic disk devices typically drive a single or multiple magnetic disks and motors for rotating magnetic disks or disks connected to the shaft by inserting shafts, bearings or bearings for supporting them, for recording and / or reproducing information. A driving device for moving the head to a desired position on the magnetic recording medium via a magnetic head, an arm attached to the head, and an arm, wherein the recording / reproducing head has a magnetic flying medium at a constant flying height. Is moved up. After the data or information is converted into the recording signals by the signal processing means, it is recorded by the magnetic head. In addition, the reproduction signals taken by the magnetic head are converted inverse by the signal processing means, so that the reproduction information can be obtained.

Information signals are recorded for each sector of the disc along tracks formed concentrically in the disc. Servo patterns are typically written between sectors. By the magnetic head taking servo signals from the servo pattern, the head accurately tracks along the center of the track to read the information signals in the sectors. Even during recording, tracking is also performed.

As described above, since a servo pattern for generating servo signals is used for tracking in information recording, high precision is particularly required. In addition, since the currently widely used servo pattern is composed of two sets of patterns shifted from each other by 1/2 pitch per track, it is necessary to form a servo pattern for each 1/2 pitch of information signals, and the precision is It is requested twice.

However, in the conventional servo pattern forming method, since the center of gravity of the external pin is different from the center of gravity of the drive device, the magnetic recording device vibrates. Thus, the width of the track was considered to be about 0.2-0.3 μm at the minimum. Therefore, the precision of the servo pattern cannot follow the increase in the track density, and it is difficult to improve the recording density or reduce the cost for the magnetic recording apparatus.

According to the present invention, since a high precision magnetic pattern can be effectively formed by using a reduced image forming technique, the servo pattern can be accurately formed at a very low cost in a short time compared with the conventional servo pattern forming method. . For example, the track density of the medium can be increased above 40 kTPI. Therefore, the magnetic recording apparatus using the magnetic recording medium according to the present invention allows high density recording.

In addition, the track density can be increased by continuously changing servo signals using a phase servo system. Since tracking is possible under conditions of width 0.1 μm or less, additional high density recording can be performed.

As described above, a magnetic pattern that linearly extends in a direction inclined with respect to the radius of the disk from the inner circumferential portion of the disk to the outer circumferential portion is used in the phase servo system. It is difficult to form a radially continuous pattern or an inclined pattern in a radius by the conventional servo pattern forming method, and while the disc is being rotated, the servo signal is recorded for each track, and complicated calculations or complex system structures are obtained. Was required.

However, according to the present invention, once the mask corresponding to the shape is sufficient to irradiate the energy beams to the mask, the pattern can be easily formed so that the medium can be easily generated in a short time with respect to the phase servo system. And economically. In addition, a magnetic recording apparatus capable of high density recording using a phase servo system can be provided.

In the conventional servo pattern forming method widely used, the medium is assembled in a magnetic recording device (drive), and then a servo pattern is formed using a servo writer for exclusive use in a clean room.

Each drive is installed on a servo writer. The lighter's pin is inserted into an opening formed in either the front or the rear of the driver, and recording is performed for each pattern along the track while the magnetic head is mechanically moved. Thus, much time is required, such as about 15 to 20 minutes per drive. Since exclusively used servo writers and openings are formed in the drive, these operations must be performed in a clean room, and the processes become complicated and the manufacturing cost increases.

In the present invention, by irradiating the energy beams through a mask in which the pattern is recorded in advance, a servo pattern or a reference pattern for recording the servo pattern can be recorded at once, and the servo pattern can be recorded in a very simple manner in a short time. Can be formed in the medium. The magnetic recording apparatus having the medium in which the servo pattern is formed does not need the above-described servo pattern recording step. The magnetic recording apparatus having the magnetic recording medium does not require the above-described servo pattern recording step.

A magnetic recording apparatus having a magnetic recording medium on which a reference pattern for recording a servo pattern is formed allows to record on a desired servo pattern based on the reference pattern. Therefore, the above-described servo writer is unnecessary, and the operations in the clean room are also unnecessary.

Further, since it is not necessary to form an opening on any side of the magnetic recording apparatus, the apparatus is preferable from the viewpoint of durability and stability.

Further, since the mask does not contact the medium, damage to the magnetic recording medium by contact with the member of another structure or damage to the medium due to the insertion of fine dust or foreign matter can be prevented to prevent the occurrence of defects.

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

Various kinds of magnetic heads such as thin film heads, MR heads, GMR heads, TMR heads, and the like may be used. By replacing the reproduced portion of the magnetic head with the MR head, sufficient signal strength can be obtained even at high density recording, and a higher recording density magnetic recording apparatus can be realized.

When the magnetic head is moved to a flying height of 0.001 µm or more and 0.05 µm or less, the output of the signal is enhanced to provide high S / N, and a highly reliable large capacity magnetic recording apparatus can be provided.

In addition, when such techniques are combined using signal processing circuits according to a particular decoding method, the recording density can be further improved. For example, when the reproduction or recording is performed at a track density of 13 kTPI or more, a linear recording density of 250 kFCI or more and a recording density of 3 G bytes or more per square inch, sufficient S / N can be obtained.

In addition, the signal strength can be further increased by replacing the reproducing portion of the magnetic head with a plurality of electrically conductive magnetic layers, which greatly changes the resistance due to the relative change of mutual magnetization directions by the application of an external magnetic field, and the GMR The head has an electrically conductive nonmagnetic layer located between the plurality of electrically conductive magnetic layers or utilizes a spin-valve effect. By using such a magnetic head, a highly reliable magnetic recording apparatus having a recording density of at least 10G bits per square inch and a linear recording density of at least 350 kFCI can be realized.

A problem may arise in that a magnetic disk (preservo disk) in which a servo pattern is recorded is attached to a rotating shoat (spindle) of the magnetic recording apparatus. That is, when the disc is assembled in the magnetic recording apparatus, the servo pattern tends to be eccentric with respect to the rotating shaft since the center of the disc does not exactly coincide with the axis center. In this case, therefore, the following calibration means is used, for example. That is, after the preservo disc is assembled in the magnetic recording medium, the amount of eccentricity of the servo track of the disc having some eccentricity with respect to the reference pattern is measured once by firmware on the side of the magnetic recording apparatus, and thereafter. The tracking pattern without eccentricity is recorded once again based on the result of the measurement.

However, the provision of such correction means increases the cost. Although the position of the head can be controlled without rewriting the servo pattern, additional tracking of the head relative to the amount of eccentricity of the disc must be done. This causes a problem that it is difficult to reduce the power consumption rate. As the track density increases, such a problem becomes more pronounced.

In view of the foregoing, a hub structure that can be attached to the rotating shaft of the magnetic recording apparatus without loosening is provided at the center portion of the substrate of the magnetic disk, and the above-described magnetic pattern formation is taken by reference to the rotation center of the hub structure. Depending on the method, the servo pattern is recorded.

Since the hub structure can be attached to the rotating shaft of the magnetic recording apparatus without loosening (to read the servo pattern), when the hub structure is attached to the rotating shaft, the rotation center of the hub structure, that is, the rotation center of the substrate, is rotated. Can be coincident with the axis center of. In addition, since the servo pattern is recorded by taking the rotational center of the hub structure as a reference, it is coaxial with the axial center of the rotational shaft with the hub structure attached to the rotational shaft.

In order to increase the accuracy of the attachment of the rotating shaft of the magnetic recording apparatus, the hub structure preferably has a thickness larger than the thickness of the substrate. The servo pattern is actually recorded by taking some positions as a reference. That is, the servo pattern is recorded by taking the reference to the inner circumferential surface of the cylindrical center opening formed in the hub structure to which the rotating shaft is fixed. Alternatively, the servo pattern is formed on the hub structure and recorded by taking the outer circumferential surface coaxial with the center of rotation.

It will be described in more detail with reference to the drawings.

11 to 16 are, respectively, longitudinal cross-sectional views of important portions of the disc according to the present invention.

The disk has a substrate 401 and a hub structure 402 on which a servo pattern for tracking servo is recorded. The substrate 401 is an information recording member such as a thin plate for recording information. On the recording surface of the disc (recording surface of the substrate 401), tracks for recording information are formed in a specific format. In addition, servo signal recording areas (servo tracks) for generating servo signals are formed in spaces between adjacent tracks that extend continuously in a direction perpendicular to the direction in which the head is moved. In the determination of the head position, a servo pattern (a series of codes for generating the servo signals) for generating the control signals for the tracking servo is recorded in the servo signal recording areas. The servo pattern is not limited to the tracking pattern to generate the servo signals, but may be a reference pattern (a series of codes for generating the reference signals) for recording the tracking pattern.

A hub structure 402 whose wall thickness is larger than the thickness of the substrate 401 is provided in the center portion of the disc for reading out the servo pattern without using the above-described calibration means. The hub structure 402 is adapted to loosely attach to the rotating shaft (spindle) 403 of the rotating mechanism in a device for reading a servo pattern, such as a hard disk device (hereinafter referred to as a "magnetic recording device"). . The servo pattern is recorded by taking a reference to the center of rotation of the hub structure 402.

As shown in FIG. 11, the substrate 401 is a donut-shaped thin plate, and the hub structure 402 is provided in the central opening of the substrate 401. Hub structure 402 is typically made of a metallic material, such as aluminum, brass, iron, stainless steel, or the like. For the hub structure 402 attached to the substrate prior to the formation of the layers by sputtering, not only formability but also thermal resistance is required. Therefore, aluminum alloy is preferably used as the material for the hub structure 402. Further, the hub structure 402 may be formed of synthetic resin such as polycarbonate, nylon, ABS resin, or the like, when the servo pattern is attached immediately before recording.

The disk may be manufactured by fabricating a substrate 401 in the same manner as a conventional disk manufacturing method, attaching a separately manufactured hub structure 402 to the substrate 401, and a predetermined servo pattern in the substrate 401. It can be prepared by using the step of recording. In the disk of synthetic resin formed by one piece of molding, this is mainly by manufacturing the substrate 401 and the hub structure 402 integrally, recording a predetermined servo pattern in the substrate 401. Are manufactured.

Hub structures 402, for example, made of metal, are typically machined, such as polishing. Hub structure 402 is typically formed to have a wall thickness that is about 3 to 10 times the wall thickness of the substrate. Using the thickness, the precision in fitting the hub structure 402 to the rotating shaft 403 of the magnetic recording apparatus can be further increased. The hub structure 402 needs to fit to the rotating shaft 403 without loosening as described above. In particular, the diameter of the center opening 421 used as a reference when recording the servo pattern is in the range of about 0 to -40 mu m, preferably in the range of -20 to -40 mu m, with respect to the diameter of the rotating shaft 403. Since the hub structure 402 is to be pressed to the rotary shaft 403 because it should have an error of. Regarding the error, the indication of “-” means that the diameter of the central opening 421 is smaller than the outer diameter of the rotating shaft 403.

When the hub structure 402 is made of aluminum alloy, the hub structure 402 is formed to have a cylindrical deformable portion (not shown) on at least one end side. As if caulking is performed, the cylindrical deformable portion is inserted into the central opening of the substrate 401, and the inserted portion is deformed to bring the hub structure 402 into a state as shown in FIG. ) May be attached to the substrate 401. The hub structure 402 may be attached at any stage between the manufacture of the disc to the substrate 401 and just before the writing of the servo pattern in the substrate 401.

The servo pattern is recorded based on the center of rotation of the hub structure 402. In particular, the hub structure 402 is provided with a cylindrical center opening 421 provided in the rotating shaft of the magnetic recording apparatus without looseness as shown in FIG. 11, and the servo pattern 402 is shown in FIG. 11. Is recorded with reference to the inner circumferential surface of the central opening 421 of (triangular display indicates a reference point). Thus, the servo pattern can be recorded concentrically around the center of rotation of the hub structure 402, and the eccentricity of the servo pattern which can be generated when the magnetic disk is assembled in the magnetic recording device can be prevented.

The recording of the servo pattern is performed in accordance with the magnetic pattern forming method described above.

As shown in FIG. 12, the hub structure for the rotating shaft or shaft 404 of the magnetic pattern forming apparatus (hereinafter may be referred to as “pattern forming apparatus”) (hereinafter may be referred to as “shaft”) The error of the center opening 421 of 402 is the error of the minus sign. By definition, the reference for recording the servo pattern (the triangular mark indicates the reference point in FIG. 12) is on the outer circumferential surface of the shaft 404 on the side of the pattern forming apparatus instead of the inner circumferential surface of the central opening 421. Can be given. Before the servo pattern is recorded, the shaft 404 is inserted into the central opening 421 of the hub structure 404 by slightly pushing the hub structure 402 after the recording, taking into account the removal of the shaft 404. Thus, the error in the diameter of the central opening relative to the diameter of the shaft 404 is in the range of about 0 to -10 mu m.

That is, the mask on which the servo pattern is formed and the disk on which the image printing is performed are arranged coaxially with respect to the axis center of the pattern forming apparatus. Thereafter, printing of the servo pattern is performed on the disk with reference to the rotational center of the disk, so that printing is performed without an eccentricity. That is, according to the method for manufacturing the disc of the present invention, the mask and the printed disc are coaxially arranged so that accurate alignment of the mask with respect to the disc can be obtained. Thus, the servo pattern in the mask can be printed on the disc without eccentricity.

By determining the error described above for the fit, the hub structure 402 can be fitted to the shaft 404 of the pattern forming apparatus without looseness. Further, by using a thick wall structure, i.e., the length of the center opening 421, the hub structure can be fitted to the shaft 404 very precisely in dimension without inclination, so that the center of rotation of the hub structure 402, i.e. The center of rotation 401 of the substrate may be aligned with the axis center of the shaft 404 of the pattern forming apparatus. Therefore, the servo pattern can be recorded concentrically with respect to the rotation center of the substrate 401.

Further, the hub structure 402 is fitted to the rotary shaft 403 of the magnetic recording apparatus without loosening by determining the error to be -20 to -40 mu m. Also, by using a thick wall structure, the hub structure can be fitted to the rotating shaft with higher precision in dimension without inclination. Therefore, the center of rotation of the hub structure 402, that is, the center of rotation of the substrate 401, may coincide with the axis center of the rotation shaft 403 at the side of the magnetic recording apparatus.

Since the servo pattern is previously recorded in the substrate 401 based on the rotation center of the hub structure 402, the position of the servo pattern in the disc is eccentric with the hub structure 402 attached to the rotating shaft of the magnetic recording apparatus. Without being coaxial with the axial center of the rotating shaft 403.

That is, using the hub structure 402 having the above-described structure, the disk can be exactly centered with the shaft, and the criterion for recording the servo pattern can be the same as the criterion for reading the servo pattern. Thus, the head can accurately read the servo pattern without using the specific calibration means and without the eccentricity.

If the pre-recorded servo pattern is only a reference pattern, the tracking pattern without an eccentricity can be accurately recorded based on such a reference pattern. As a result, the cost for processing servo signals can be reduced. In particular, such a method is effective for high density recording. In addition, since the amount of tracking by the head is further reduced, the power consumption rate required for reading and / or writing information can be further reduced.

Also, the reference point of the hub structure for the disk can be determined at such locations as shown in FIGS. 13 and 14. That is, the hub structure 402 has an outer circumferential surface 422 coaxial with the center of rotation, and the servo pattern is recorded with reference to the outer circumferential surface 422 of the hub structure 402.

In particular, the hub structure 402 typically has a round columnar shape, the upper end side of which is in the frustum of the cone. The hub structure 402 can be fitted to the rotation shaft 403 of the magnetic recording apparatus or the shaft 404 of the pattern forming apparatus without loosening. In addition, the shape of the cross section of the round columnar portion of the hub structure 402 is a true circle, which is taken perpendicular to the axis centerline of the portion. Thus, the servo pattern can be recorded with reference to the outer circumferential surface 422 of the round columnar portion of the hub structure 402 (triangle marks represent reference points).

As described above, since the outer circumferential surface 422 of the hub structure 402 is formed to have a true circle, its center is coaxial with the center of rotation of the hub structure, and the outer circumferential surface 422 is determined as a reference. Even in the case, based on the rotation center of the hub structure 402, the servo pattern may be written to the substrate 402 coaxially. The embodiment shown in Fig. 13 is effective when the rotating shaft 403 of the magnetic recording apparatus or the shaft 404 of the pattern forming apparatus is not exposed to the outside or has a small diameter, so it is difficult to use it as a reference.

The hub structure 402 shown in FIG. 14 has substantially the same structure as the structure shown in FIG. The hub structure 402 is adapted to loosely attach to the rotating shaft 403 of the magnetic recording apparatus or the shaft 404 of the pattern forming apparatus, wherein the rotating shaft 403 or the shaft 404 is of a larger diameter cylinder. It is formed to have a shape. That is, the round pillar shape of the hub structure 402 may be attached to the rotary shaft 403 or shaft 404 by fitting the round pillar shape to the rotary shaft 403 or the distal opening of the shaft 404. . The cylindrical rotating shaft 403 or shaft 404 having a larger diameter corresponds to a case-like rotating body attached to an actual rotating shaft extending from the motor.

Also in this case, if the shape is an actual circle in the outer circumferential surface 422 of the hub structure 402 and in the cross-sectional view of the rotary shaft 403 or the shaft 404, the axis centers of these members are the same as those of FIG. In the same way, based on the outer circumferential surface of the rotating shaft 304 or shaft 404 coaxial with each other, the servo pattern is relative to the substrate 401 relative to the center of rotation of the hub structure 402. Can be recorded concentrically.

In addition, even in the disc of the present invention shown in Figs. 13 and 14, the alignment of the disc with respect to the shaft can be obtained by the loose wall fitting structure and the thick wall structure with respect to the hub structure 402, and Fig. 11 And in the same manner as the disk shown in FIG. 12, the criteria used to record the servo pattern may be the same as the criteria used to read the servo pattern. Thus, the servo pattern can be read accurately by the head without using specific calibration means. Also, when the previously recorded servo pattern is only a reference pattern, the tracking package can be recorded accurately based on the reference pattern. The rotating shaft 403 or the shaft 404 can be a shaft formed as an inner surface of the bearing. Such a shaft is preferred because its outer circumferential surface ensures high concentricity with respect to the center of rotation.

The hub structure can be changed as long as the servo pattern can be prerecorded with reference to the center of rotation of the hub structure. For example, the hub structure 402 shown in FIG. 15 includes a hub columnar body 423 such as a round pillar having a stepped portion: an outer circumferential portion having a larger diameter and an outer circumferential portion having a smaller diameter; A fitting ring 424 is attached to the outer diameter portion of the smaller diameter.

At the center of the hub main body 423, a cylindrical center opening 421 is formed, and the rotating shaft 403 of the magnetic recording apparatus or the shaft 404 of the pattern forming apparatus can be fitted without looseness. The inner diameter of the smaller portion of the hub main body 423 is formed to fit with the central opening of the substrate 401 with the above-described error without looseness. The hub structure 402 is attached to the substrate 401 by press fitting the fitting ring 424 to the outer circumferential portion of the smaller diameter hub main body 423 that has been inserted into the central opening of the substrate.

In the disc provided with such a hub structure 402, the servo pattern is recorded with reference to the inner circumferential surface of the central opening 421 of the hub main body 423 in the same manner as in FIG. Alternatively, the servo pattern is recorded based substantially on the outer circumferential surface of the shaft 404 of the pattern forming apparatus fitted in the central opening 421 in the same manner as in FIG. 12. Further, as long as the outer circumferential surface 422 of the hub main body 423 is formed to have an actual circle having a center coaxial with the center of rotation of the hub structure (triangle marks indicate respective reference points in FIG. 15), In the same manner as in FIG. 13, the hub servo pattern can be recorded substantially based on the outer circumferential surface 422 of the hub main body 423.

In addition, in the disk shown in FIG. 15, a servo pattern without an eccentricity may be recorded on the substrate 401 based on the rotation center of the hub structure 402 in the same manner as the above-described embodiments. In addition, when the magnetic recording medium is assembled in the magnetic recording apparatus, accurate alignment can be achieved by the unique structure of the hub structure 402. Further, the reference used to record the servo pattern can be the same as the reference for reading, the servo pattern can be read accurately without using specific calibration means, and the tracking means can be recorded accurately based on the reference pattern. .

Also, in the disk shown in FIG. 16, the hub structure 402 may be integrally formed with the substrate 401. That is, the hub structure 402 has substantially the same structure as in FIG. 11, and the hub structure has a cylindrical shape that is loosely fitted to the rotating shaft 403 of the magnetic recording apparatus or the shaft 404 of the pattern forming apparatus. The central opening 421 of is provided. Subsequently, based on the center of rotation of the hub structure 402 with respect to the substrate 401 taken as a reference, a servo pattern is recorded with reference to the inner circumferential surface of the center opening 421 actually. Alternatively, the servo pattern is recorded with reference to the outer circumferential surface of the shaft 404 of the pattern forming apparatus in the same manner as that of the embodiment of FIG. 12 (a triangle mark indicates a reference point in FIG. 12).

In the disk shown in FIG. 16, a servo pattern without an eccentricity can be recorded on the substrate 401 based on the rotation center of the hub structure 402 in the same manner as the above-described embodiments. In addition, in the case where the disc is assembled in the magnetic recording apparatus, the precise alignment of the shaft can be achieved by the unique structure of the hub structure 402. Also, the criteria used to record the servo pattern may be the same as the criteria used to read. Thus, the servo pattern without eccentricity can be read accurately without using specific correction means. Also, the tracking pattern without eccentricity can be recorded accurately based on the reference pattern. In the disk shown in Fig. 16, since the hub structure 402 can be formed integrally with the substrate 401, the manufacturing cost can be further reduced when they are manufactured by the above-described synthetic resin.

Further, as shown in Fig. 16, the inner circumferential surface of the center opening 421 or the outer circumferential surface of the rotating shaft 403 fitted to the center opening is taken as a reference at the time of recording the sub pattern, and the hub structure ( The central opening 421 of 402 may be an opening in which the diameter of the central opening along the longitudinal axis of the opening is slightly larger. That is, when the rotary shaft 403 of the magnetic recording apparatus or the shaft 404 of the pattern forming apparatus is inserted into the central opening 421, both edge portions of the central opening are formed on the rotary shaft 403 or the shaft 404. The central opening 421 of the hub structure 402 is so adapted so that the center of rotation of the hub structure 402 coincides with the axis of rotation of the shaft 403 or the shaft 404 in contact with.

The shape of the central opening 421 described above may be formed using a "shrinkage cavity" into which a mold made of resin is injected to form the hub structure 402. That is, in the hub structure 402, after mold injection such that the diameter of the center portion is larger than the diameter of both edge portions, large shrinkage pores are generated in the center portion with the large wall thickness.

In the hub structure made of resin, in view of mold precision, the center opening 421 is typically formed such that the rotary shaft 403 or the shaft 404 is forcibly inserted into the opening. However, either the rotating shaft 403 or the shaft 404 fits into the central opening 421 having a straight tube-like shape, and the substrate 402 is inclined by a small defect mold on the inner circumferential surface of the central opening 421. Can be. However, in the above-described hub structure 402 having small diameter portions at both edge portions of the central opening 421, the rotary shaft 403 or the shaft 404 forcibly inserted into the central opening 421 is the center opening ( The inclination of the substrate 402 supported by two support points at both edge portions of 421 and attached to the shaft can be reliably prevented.

A magnetic recording disk on which the disk of the present invention is assembled is described.

As a head support arm having a rigid structure, the magnetic head is attached to the upper end of the load beam, and the load beam is attached to the upper end of the swivel head arm using a driving device, with the load beam being driven to the side of the disk. do. The head has a block-shaped slider that provides an air bearing to the disk, and a magnetic head located on the lower surface of the slider. The magnetic head serving as a servo signal detection means is located in a direction perpendicular to the direction of movement of the head and is provided with at least two head gaps for tracking.

The control means for controlling the tracking functions to analyze the servo pattern read by the head gaps to control the moving position of the head. In particular, the head gaps are arranged at positions shifted by, for example, 0.5 times, 1.5 times, ... of the pitch of the information recording tracks when the magnetic head is exactly on the track. The control means performs tracking control on the magnetic head based on the change in the intensity of the reproduced servo signals. When the magnetic head is out of the center of the track, the output of the signals from the head gaps is increased or decreased. Thus, the control means measures the signal outputs to obtain an error on the center of the magnetic head with respect to the center of the track, whereby the control head is controlled to be positioned exactly on the track.

The mechanism for rotating the disk mainly comprises a spindle motor having the above-mentioned rotating shaft 403 to which a single or a plurality of the above-mentioned disks are fitted as shown in the figures. In addition, since such disks or disks having the hub structure 402 are fitted to the rotating shaft 403 of the disk rotating mechanism without loosening, the servo pattern in the substrate 401 has an eccentricity with respect to the axis center of the rotating shaft 403. Are located concentrically without.

Thus, in the magnetic recording apparatus, when the servo pattern is read by the head relative to the center of rotation of the hub structure 402, and the outer circumferential surface of the rotating shaft 403 is used as a reference, for example, the servo pattern The criterion for reading is the same as the criterion for writing the servo pattern. Thus, the servo pattern without eccentricity can be read accurately. Also, when the previously recorded servo pattern is only a reference pattern, the tracking pattern can be accurately recorded based on the reference pattern without using specific correction means. As a result, the cost for processing servo signals can be reduced. This technique is effective when increasing the density of information to be recorded. In addition, since the amount of tracking by the head is smaller, the power consumption rate for recording and / or reading information can be further reduced.

The invention is now described in more detail with reference to embodiments. However, it should be understood that the present invention is in no way limited to such specific embodiments.

Example 1-1

An aluminum silicate-type glass substrate having a diameter of 2.5 inches was cleaned and dried, and the extreme process degree was 1 × 10 ⁻⁷ Torr, the substrate temperature was 350 ° C., the bias voltage was −200 V, the sputtering gas was Ar, and the gas pressure was 3 ×. Under such conditions of 10 ^-3 Torr, 60 nm NiAl, 10 nm C _r94 Mo ₆ , 22 nm Co ₇₂ Cr ₁₈ Pt ₁₀ , and 5 nm carbon (diamond-based carbon) as the protective layer thereon Formed.

Surface roughness Ra was 0.5 nm and surface relief Wa was 0.8 nm. As a lubricating layer, a fluorine-type lubricating layer was coated thereon to a thickness of 1.5 nm and baked at 100 ° C. for 40 minutes to obtain a horizontal recording magnetic disk having a coercivity of 3000 Oe and a saturation magnetization of 310 emu / cc at room temperature. . The Curie temperature of the recording layer was 250 ° C.

The disk surface was uniformly magnetized by applying a magnetic field with an intensity of about 10 k Gauss (10 kOe) to the disk such that the magnetic direction of the electromagnet was the same as the direction of rotation of the disk.

(

는 자기 투자율을 나타낸다)의 관계를 가지며,

는 공기중에서 1 이다. 따라서, 측정된 자계 세기의 값이 10k Gauss 일 때, 이는 10 kOe 의 자계를 인가하는 것과 같다.Here, the magnetic strength B (Gauss) and the magnetic field H (Oe)

(

Represents the self-permeability),

Is 1 in the air. Thus, when the value of the measured magnetic field strength is 10k Gauss, this is equivalent to applying a magnetic field of 10 kOe.

Then, while rotating the disk at a rotational speed of 1000 rpm, an argon laser having a wavelength of 514.4 nm has a duty cycle of 20%, a power (energy density) of 110 Hz and a beam diameter of 15 µm (1 / peak energy). e ² Pulsed and irradiated under such conditions, the diameter of which was taken as the beam diameter), and the irradiated portion was heated to a level close to the Curie temperature to eliminate magnetism.

The presence or absence of magnetic pattern formation in this disk is confirmed by developing the magnetic pattern using a magnetic developer and by observing it with an optical microscope. As a result, a magnetic pattern matching the pattern of the pulsed laser was obtained on the disk surface.

의 부호는 패턴이 형성됨을 표시하고,

의 부호는 패턴이 만족스럽게 형성됨을 표시하고, ◎ 의 부호는 패턴이 명료하게 형성됨을 표시한다.In addition, evaluation of the clearness of the magnetic pattern was performed by developing the magnetic pattern by a magnetic developer and observing it with an optical microscope. The results are shown in Table 1.

Indicates that the pattern is to be formed,

Indicates that the pattern is satisfactorily formed, and indicates that the pattern is formed clearly.

In addition, the clearness of the magnetic pattern was also confirmed by reproducing the magnetically patterned signal by the MR head having a reproducing element width of 0.9 mu m. The 50% (ie, half width) of the magnetization pulse width (corresponding to the magnetic transition width) of the maximum magnetization in the reproduced signal waveform was 1.3 μm.

Example 1-2

Magnetic disks produced in the same manner as in Example 1-1 were magnetized uniformly in the same manner as in Example 1-1.

Thereafter, a Cr mask was produced having transparent portions and non-transmissive portions formed by protrusions (height: about 20 nm) and recesses of Cr on the glass. As shown in Fig. 17, the transmission pattern repeated every 1 mu m in the radial direction between the position in the radius of 15 nm and the position in the radius of 30 nm is repeated every 45 degrees in the circumferential direction. The protrusions are non-transmissive parts, the recesses are transmissive parts, and the protrusions are closer to the disk.

20 is a diagram showing an embodiment of a magnetic pattern forming apparatus used in this example. On the turntable 306 fixed to the rotatable spindle 308, a mask having a desired pattern is formed, a magnetic disk 301 is installed, and then to the fixing portion 305 of the disk and the mask, eg For example, it is fixed by a screw, and then vacuum fixed by a groove 307. Although not shown, a laser 304 that passes through the objective lens through various optical systems and emitted from the laser source passes through the shading substrate 303 and is projected onto the magnetic disk 301. The beam-shaped laser 304 becomes a fan shape after passing through the shading substrate, enters the mask 302, and is irradiated onto the disk 301 matching the pattern shape. Although not shown, fine recesses and protrusions corresponding to the pattern to be formed are formed on the mask 302.

It is a figure which shows the Example of the optical system for laser irradiation. The laser emitted from the laser source is passed through a programmable shutter and then attenuator, the beam diameter is enlarged and parallel light by the collimeter lens, the beam intensity is uniform by the homogenizer, It is irradiated with a magnetic recording medium (magnetic disk).

의 펄스 폭을 가지는 펄스 레이저에 대응한다. 상술된 바와 같이, 레이저는 디스크상의 자기 패턴을 형성하도록 조사되었다.The mask and magnetic disk were installed on the apparatus as shown in Fig. 20, and the mask was in close contact with the magnetic disk. While rotating the magnetic disk at a rotational speed of 1000 rpm, an argon laser having a wavelength of 514.5 nm with a power of 110 mW and a beam diameter of 15 μm was continuously irradiated, and irradiated at a level close to the Curie temperature to cancel the magnetism. Part was heated. The laser irradiation optical system shown in FIG. 23 was used. The energy density in this case was about 104 mJ / cm ² , when the irradiation of the transmissive part of the mask was pulsed, it was 4.8 in the outermost part.

It corresponds to a pulse laser having a pulse width of. As described above, the laser was irradiated to form a magnetic pattern on the disc.

Evaluation of the produced disc was performed in the same manner as in Example 1-1. The results are shown in Table 1. The half width of the reduced signal waveform was 1.2 mu m.

In addition, the laser was irradiated through the mask along the entire circle of the disk, whereby repeating patterns of transmissive and non-transmissive portions of the mask were obtained over the entire area irradiated by the laser.

Thereafter, by Raman spectroscopy, peak values of graphite and diamond were measured to confirm the damage of the protective layer by laser irradiation. If the protective layer is damaged, the peak intensity of the diamond after irradiation with the laser beam should decrease and the peak intensity of the graphite should increase. However, in this example, the peak ratio did not change before and after irradiation. In addition, the weight of the average molecular weight and the number of the average molecular weight of the lubricating layer were measured to confirm the presence of damages such as decomposition or polymerization. However, no difference was observed before or after laser irradiation.

If the method of this embodiment is applied for the formation of the servo pattern of the magnetic disk, a magnetic disk having a high precision servo pattern can be obtained simply and in a short period of time. In addition, using a magnetic disk apparatus using such a magnetic disk, it is possible to perform tracking with high precision and to perform recording at a high density without having to rewrite a servo pattern.

Example 1-3

An aluminum silicate-type glass substrate having a diameter of 2.5 inches was cleaned and dried, and the degree of extreme vacuum was 1.2 x 10 ^-6 Torr, the substrate temperature was room temperature, the sputtering gas was Ar, the gas pressure was 3 x 10 ^-3 Torr, and the bias voltage. Under such conditions of 0V, 300 nm of Ni ₅₀ Fe ₅₀ , 30 nm of Tb ₂₀ Fe ₆₈ Co ₁₂ , 2 nm of Cr and 5 nm of carbon (diamond-based carbon) as the second protective layer Formed on top.

Surface roughness Ra was 0.8 nm and surface relief Wa was 1.0 nm. As a lubricating layer, a fluorine type lubricating layer was coated thereon to a thickness of 1.5 nm and baked at 100 ° C. for 40 minutes to obtain a vertical recording magnetic disk having a saturation magnetization of 70 emu / cc and a vertical coercive force of 3,500 Oe. The Curie temperature of the recording layer was 230 ° C.

The disk surface was uniformly magnetized by applying a magnet with an intensity of about 10 k Gauss to the disk so that the magnetic direction of the electromagnet was perpendicular to the disk surface. Thereafter, in the same manner as in Example 1-1, except that the power was changed to 130 mW, the laser irradiated portions were heated to a level close to the Curie temperature to eliminate magnetism.

Evaluation of the produced disc was carried out in the same manner as in Example 1-1. The results are shown in Table 1.

Example 1-4

Magnetic disks were produced in the same manner as in Example 1-1. While rotating the disk at a rotational speed of 1,000 rpm, an argon laser having a wavelength of 514.5 nm with a power of 70 kW and a beam diameter of 15 탆 was pulsed and irradiated with a duty cycle of 20%. At the same time, in the recording layer, a magnetic field was applied at a recording current of 15 mA to magnetize in the rotational direction of the disc by the magnetic head. Evaluation of the produced disc was carried out in the same manner as in Example 1-1. The results are shown in Table 1.

Example 1-5

Magnetic disks produced in the same manner as in Example 1-1 were magnetized uniformly in the same manner as in Example 1-1. Thereafter, while rotating the disk at a rotational speed of 1,000 rpm, an argon laser having a wavelength of 514.5 nm with a power of rotation of 100 Hz and a beam diameter of 15 μm was pulsed and irradiated with a duty cycle of 20%. At the same time, in the recording layer, a magnetic field with a recording current of 15 mA was applied to magnetize in the direction opposite to the rotation direction of the disc by the magnetic head. Evaluation of the produced disc was carried out in the same manner as in Example 1-1. The results are shown in Table 1.

Example 1-6

Magnetic disks produced in the same manner as in Example 1-1 were magnetized uniformly in the same manner as in Example 1-1. Thereafter, a Cr mask was produced having transparent portions and non-transmissive portions formed by protrusions (height: about 20 nm) and recesses of Cr on the glass. As shown in Fig. 18, a transmission pattern having a length (radius: 15 mm to 30 mm) in the radial direction and a width of 2 m in the circumferential direction was repeated every 45 degrees in the circumferential direction. Magnetic disks were placed thereon.

21 is a diagram showing still another embodiment of the magnetic pattern forming apparatus. In addition to the apparatus shown in FIG. 20, a magnet 309 is disposed as an external magnetic field applying means so that an external magnetic field can be applied simultaneously with heating by laser irradiation.

The mask and magnetic disk were installed on the apparatus of FIG. 21 and the excimer laser was irradiated from the side of the mask. While the angle is adjusted so that the transmission pattern is at the center of the laser spot, an excimer laser with a wavelength of 248 nm and a pulse width of 25 nsec with a power of 80 mJ / cm ² and a beam shape of 10 mm x 30 mm is obtained. The irradiated portion was irradiated at a frequency of kHz and the irradiated portion was heated to a level close to the Curie temperature. The laser irradiation optical system shown in FIG. 23 was used. At the same time, by means of a permanent magnet, a magnetic field of about 1.5 k Gauss was applied to the energy beam irradiation portions in a direction opposite to the initial uniform magnetization. The magnetic pattern was thus formed.

Evaluation of the produced disk was carried out in the same manner as in Example 1-1. The results are shown in Table 1. In addition, the obtained reproduction signal waveform is shown in Fig. 24C. The waveform of half the value of the reproduced signal waveform was 0.25 탆.

Damages to the protective layer and the lubricating layer were evaluated in the same manner as in Example 1-2, and no deterioration of the protective layer or the lubricating layer was observed.

Example 1-7

NiP plated Al substrates having a diameter of 3.5 inches were cleaned and dried, and the degree of extreme vacuum was 1 × 10 −7 Torr, substrate temperature; 60 nm NiAl, 10 nm Cr ₉₄ Mo ₆ , 25 nm Co ₇₀ Cr as a recording layer under such conditions as 350 ° C., bias voltage: -200 V, sputtering gas: Ar and gas pressure: 3 × 10 ⁻³ Torr. ₁₃ Ta ₅ Pt ₁₂ and 5 nm of carbon (diamond-based carbon) were formed thereon as a protective layer.

Surface roughness Ra was 06 nm and surface relief Wa was 0.9 nm. As a lubricating layer, a fluorine lubricating layer was coated thereon to a thickness of 1.5 nm and baked at 100 ° C. for 40 minutes to obtain a magnetic disk having a coercivity of 3,400 Oe and a saturation magnetization of 320 emu / cc at room temperature. The Curie temperature of the recording layer was 350 ° C.

The disk was magnetized uniformly in the same manner as in Example 1-1, after which the magnetic disk was the same as in Example 1-6 except that the radial length was 20 mm (radius: 20 mm to 40 mm). Placed on the mask.

From the side of the mask, the YAG-Q-switched laser was irradiated. While adjusting the angle so that the transmission pattern is in the center of the laser spot, a YAG-Q-switched laser having a wavelength of 266 nm and a pulse width of 5 nsec with a power of 50 mJ / cm ² and a beam diameter of 20 mm is 10 It was irradiated over the entire surface of the disc at a frequency of kHz and the irradiated portion was heated to a level close to the Curie temperature. During the heating, a magnetic field was applied in the same manner as in Example 1-6. In addition, the structure of the mechanical system and the optical system of the apparatus for forming the magnetic pattern was the same as in Example 1-6.

Evaluation of the produced disc was carried out in the same manner as in Example 1-1. The results are shown in Table 1.

Example 1-8

Magnetic disks were produced in the same manner as in Examples 1-7.

For discs inserted between magnets of the same polarity (at 3 mm intervals) the magnets of the same polarity face each other, and on the same side (at 15 mm intervals) different yokes are attached to the yoke so as to face each other. Multiple permanent magnets have been placed. As a result, magnetization means having a magnetism of about 7 k Gauss at the surface of the disk in the direction of contact with the circumference was obtained, and while the disk was rotated, the disk was magnetized uniformly in the circumferential direction.

Thereafter, the same mask as in Example 1-7 was produced except that the width in the circumferential direction was 0.5 µm, and a magnetic disk was disposed thereon in the same manner as in Example 1-7, and the disk was subjected to laser irradiation. Was heated and an external magnetic field was applied in the direction opposite to the initial uniform magnetization during heating.

Evaluation of the produced disc was carried out in the same manner as in Example 1-1. The results are shown in Table 1.

Example 1-9

A magnetic disk was produced in the same manner as in Examples 1-8, and the disk was magnetized uniformly in the circumferential direction.

Thereafter, a Cr mask was produced having transmissive and non-transmissive portions formed by recesses and protrusions (height: about 20 nm) of Cr on the glass. As shown in FIG. 19, the mask has transmissive patterns having a width of 8 μm repeated radially by 10 mm (radius: 30 mm to 40 mm). Each pattern consists of a plurality of transmissive parts and non-transmissive parts that extend obliquely, with an angle θ = 35 degrees and a width of 2 μm with respect to the radial direction.

The magnetic disk was placed thereon in the same manner as in Example 1-7, the laser was irradiated to heat the disk, and an external magnetic field was applied under the same conditions as in Example 1-7.

Evaluation of the produced disk was carried out in the same manner as in Example 1-1. The results are shown in Table 1. In addition, the obtained reproduction signal waveform is shown in Fig. 24B. The half width of the reproduction signal waveform was 0.32 mu m. A photograph of the obtained gradient magnetic patterns is shown in Fig. 24C.

Damages of the protective layer and the lubricating layer were evaluated in the same manner as in Example 1-2, but no degradation of the protective layer or the lubricating layer was observed.

For each of the disks of Examples 1-6 to 1-9, the laser was irradiated through the mask over the entire circle, thereby transmitting and non-transmissive portions of the mask over the entire area irradiated with the laser. Patterns by the repetition of these were obtained.

In addition, in each of Examples 1-6 to 1-9, the magnetic disk and the Cr mask were contacted with each other by the relief of the mask and the magnetic disk, and the contact pressure was generated by the weight of the disk itself, which was about 0.2 g / cm ² . That is, although the mask and the disk are not in close contact with each other, the disk is simply disposed on the mask, so that more sufficiently fine magnetic patterns can be formed. By such a simple arrangement, it is possible to minimize the possibility of forming damages and at the same time form fine patterns.

By applying the methods of these embodiments, it is possible to obtain a magnetic disk having a high precision servo pattern simply and in a short period of time when forming a servo pattern of the magnetic pattern. In addition, using a magnetic disk apparatus using such a magnetic disk, it is possible to perform tracking with high precision and to perform recording at a high density without the need to rewrite the servo pattern.

Example 2-1

Magnetic disks were produced in the same manner as in Example 1-1. The surface roughness Ra was 0.6 nm and the surface relief was 0.9 nm.

FIG. 22 is a diagram showing yet another embodiment of an apparatus for forming a magnetic pattern. FIG. The difference from the apparatus shown in FIG. 20 is that a space is formed between the mask 302 and the magnetic disk 301 by an inner peripheral spacer 310 and an outer peripheral spacer 311, which are examples. For example, it is fixed to the fixing portion 305 of the mask and the disk by screws, and is vacuum fixed by the groove 307.

The mask and magnetic disk were installed on the apparatus of FIG. 22 with a space of about 10 μm in between, and from the side of the mask, an excimer pulsed laser was irradiated. The mask was a Cr mask using quartz glass as the substrate and the minimum width of the transmissive portions was 1 μm.

With a beam shape of 10 nm × 30 mm and a power of 80 mJ / cm ^2, an excimer pulse laser having a wavelength of 248 nm and a pulse width of 25 nsec was irradiated, and the irradiated portion was heated to a level close to the Curie temperature. . A laser irradiation optical system as shown in FIG. 23 was used. At the same time, a magnetic field of about 2.3 k Gauss was applied to the portion irradiated with the energy beam in the circumferential direction by the permanent magnet. As a result, a magnetic pattern was formed.

Evaluation of the produced disk was carried out in the same manner as in Example 1-1. The results are shown in Table 2. In addition, damages of the protective layer and the lubricating layer were evaluated in the same manner as in Example 1-2, but no degradation of the protective layer or the lubricating layer was observed.

If the method of this embodiment is applied to the formation of the servo pattern of the magnetic disk, a magnetic disk having a high precision servo pattern can be obtained simply and in a short period of time. In addition, using a magnetic disk apparatus using such a magnetic disk, it is possible to perform tracking with high precision and to perform recording at a high density without the need to rewrite the servo pattern.

Example 2-2

Magnetic disks were made in the same manner as in Example 2-1, except that a NiP plated Al substrate having a diameter of 3.5 inches was used. The surface roughness Ra was 0.6 nm and the surface relief Wa was 0.9 nm.

The disk was magnetized uniformly in the circumferential direction by an external magnetic field of 10 k Gauss, and then the excimer pulsed laser was irradiated through the mask in the same manner as in Example 2-1. Simultaneously with the irradiation of the laser, a magnetic field of about 4 k Gauss was applied in a direction perpendicular to the main surface of the magnetic recording medium. Thus, a magnetic pattern was formed. Evaluation was performed in the same manner as in Example 2-1, and the results are shown in Table 2.

Example 2-3

A magnetic disk made in the same manner as in Example 2-1 was magnetized uniformly in the circumferential direction by an external magnetic field of 10 k Gauss, except that a NiP plated Al substrate having a diameter of 3.5 inches was used, and then the Example In the same manner as in 2-1, an excimer pulsed laser was irradiated through the mask and at the same time an external magnetic field was applied in a direction opposite to the initial uniform magnetization. Evaluation was performed in the same manner as in Example 2-1, and the results are shown in Table 2.

Also, a magnetic pattern was formed on the magnetic recording medium under the same conditions, and the magnetic pattern was reproduced by an MR head having a reproduction element width of 0.9 mu m, whereby the peak output (peak peak) of the isolated waves was measured. The results are shown in Table 3.

In addition, the number of missing pulses on the surface on which the magnetic pattern was formed was 1.1 μm recording element width, 0.7 μm reproduction element width, 1.3 μm flying height, 160 kFCI recording frequency, 1 μm inspection pitch, and 65% slice level. Was evaluated using. 25 (c) shows the results of mapping the number of missing pulses on the medium. No major defects were observed.

When the magnetic pattern forming method of the present invention is applied to recording a servo pattern on a magnetic disk, a clear servo pattern can be formed and also suppress the formation of defects. Therefore, using a magnetic disk device using such a magnetic disk, it is possible to perform recording with high reliability and with high density.

Example 2-4

Magnetic disks were produced in the same manner as in Example 2-1. Ra was 0.5 nm and Wa was 0.8 nm.

The disk was magnetized uniformly in the circumferential direction by an external magnetic field of 10 k Gauss, and then the excimer pulsed laser was irradiated through the mask in the same manner as in Example 2-1. Simultaneously with the irradiation of the laser, a magnetic field of about 4 k Gauss was applied in a direction perpendicular to the main surface of the magnetic recording medium. Thus, a magnetic pattern was formed. Evaluation was performed in the same manner as in Example 2-1, and the results are shown in Table 2.

Example 2-5

Magnetic disks were produced in the same manner as in Example 2-1. Ra was 0.5 nm and Wa was 0.8 nm.

The disk was magnetized uniformly in the circumferential direction by an external magnetic field of 10 k Gauss, and then in the same manner as in Example 2-1, the excimer pulsed laser was irradiated through the mask while the external magnetic field was initially uniformly magnetized. Was applied in the opposite direction to. Evaluation was performed in the same manner as in Example 2-1, and the results are shown in Table 2.

Example 2-6

An aluminum silicate-type glass substrate having a diameter of 2.5 inches was cleaned and dried, and the degree of extreme vacuum was 1 × 10 ^-7 Torr, the substrate temperature was 350 ° C., the bias voltage was -200V, the sputtering gas was Ar, and the gas pressure was 3 ×. Under such conditions of 10 ⁻³ Torr, 500 nm of Ni ₅₀ Fe ₅₀ , 30 nm of TbFeCo and 5 nm of carbon (diamond-based carbon) were formed on the glass substrate as a recording layer. As a lubricating layer, a fluorine type lubricating layer was encoded thereon to a thickness of 1.5 nm and baked at 100 ° C. for 40 minutes. The resulting vertical recording magnetic disk had a saturation magnetization of 70 emu / cc, a coercive force of 400 Oe at room temperature, and a Curie temperature of 230 ° C.

The resulting disk was uniformly magnetized in a direction perpendicular to the main surface of the magnetic recording medium by an external magnetic field of 10 k Gauss.

Thereafter, an excimer pulsed laser was irradiated through the mask in the same manner as in Example 2-1. At the same time, as an external magnetic field, a magnetic field of about 4 k Gauss was applied in a direction perpendicular to the main surface and opposite to the direction of initial uniform magnetization of the magnetic recording medium. Thus, a magnetic pattern was formed. Evaluation was performed in the same manner as in Example 2-1, and the results are shown in Table 2.

Example 2-7

Magnetic disks were made in the same manner as in Example 2-1 except that a NiP plated Al substrate having a diameter of 3.5 inches was used. The surface roughness Ra was 0.6 nm and the surface relief Wa was 0.9 nm.

The mask was magnetized uniformly in the circumferential direction by an external magnetic field of 10 k Gauss, after which the excimer laser was irradiated through the mask in the same manner as in Example 2-1 except that the pulse width was changed to 5 nsec, and at the same time the external A magnetic field was applied in the direction opposite to the initial uniform magnetization. Thus, a magnetic pattern was formed. Evaluation was performed in the same manner as in Example 2-3, and the results are shown in Tables 2 and 3.

Example 2-8

Magnetic disks were made in the same manner as in Example 2-1 except that a NiP plated Al substrate having a diameter of 3.5 inches was used. The surface roughness Ra sms was 0.6 nm and the surface relief was Wa was 0.9 nm.

The disk was magnetized uniformly in the circumferential direction by an external magnetic field of 10 k Gauss, after which the excimer pulsed laser was irradiated through the mask in the same manner as in Example 2-1 except that the pulse width was changed to 50 nsec. At the same time an external magnetic field was applied in the direction opposite to the initial uniform magnetization. Thus, a magnetic pattern was formed. Evaluation was performed in the same manner as in Example 2-3, and the results are shown in Tables 2 and 3.

Example 2-9

Magnetic disks were produced in the same manner as in Example 2-3, and were uniformly magnetized in the circumferential direction by an external magnetic field. Then, in order to form a magnetic pattern, a Cr mask using quartz glass as a substrate and having a minimum width of transmission portions of 1 μm was disposed on the disk with a space of about 10 μm, and a YAG having a wavelength of 266 nm. The -Q-switched laser was irradiated with a pulse width of 5 nsec and with altered power and beam diameter as shown in Table 4, while at the same time the magnetic field of about 2.3 k Gauss was reversed by the direction of initial uniform magnetization by the permanent magnet. In the direction of phosphorus.

The evaluation was performed in the same manner as in Example 2-3, and the results are shown in Table 4. Clear magnetic patterns were formed using power in the range of about 30-65 mJ / cm ² . However, this was clearer than the magnetic pattern formed in Example 2-3. This is thought to be due to the fact that the pulse width was shortened to 5 nsec. FIG. 26 shows micrographs (magnification: 329 times) when the power was 49.8 mJ / cm ² . In addition, the output waveform is shown in Fig. 27A.

Example 2-10

In the same manner as in Example 2-3, a magnetic disk was manufactured and uniformly magnetized in the circumferential direction by an external magnetic field.

Thereafter, a Cr mask was produced having transmissive and non-transmissive portions formed by recesses and protrusions (height: about 20 nm) of Cr on the glass. As shown in FIG. 19, the mask had transmissive portions having a width of 8 μm repeated radially about 10 mm (radius: 30 mm to 40 mm). Each pattern consists of a plurality of transmissive parts and non-transmissive parts extending inclined at an angle θ = 35 degrees based on the radial direction, each width of 2 μm.

Using this mask, an excimer pulsed laser was irradiated onto the magnetic disk in the same manner as in Example 2-1, while at the same time an external magnetic field was applied in a direction opposite to the initial uniform magnetization. Evaluation was performed in the same manner as in Example 2-1, and the results are shown in Table 2.

In addition, Fig. 27C shows the envelope of the reproduction output waveform of the obtained magnetic pattern. For comparison, Fig. 27 (b) shows the same manner as in the case of the mask of Fig. 19, in which the magnetic pattern was formed at an angle? Shows a reproduced signal waveform when formed. As described above, with the use of the inclined pattern so far, the output tended to decrease. On the other hand, according to this embodiment, even when using the inclined pattern, no substantial change in the output was observed.

Example 2-11

Magnetic disks were produced in the same manner as in Example 2-1, except that a NiP plated Al substrate having a diameter of 3.5 inches was used. The surface roughness Ra was 0.6 nm and the surface relief Wa was 0.9 nm.

The mask was magnetized uniformly in the circumferential direction by an external magnetic field of 10 k Gauss.

Thereafter, the mask was placed on the disk, the pressure between the disk and the mask was reduced such that they were in close contact with each other, and the excimer pulsed laser was changed in Example 2-1 except that the pulse width was changed to 50 nsec. It was irradiated through the mask in the same manner as, and at the same time an external magnetic field was applied in the direction opposite to the initial uniform magnetization. Thus, a magnetic pattern was formed. Evaluation was performed in the same manner as in Example 2-3, and the results are shown in Tables 2 and 3.

In addition, the number of missing pulses on the surface on which the magnetic pattern was formed was evaluated in the same manner as in Example 2-3. The results are shown in FIG. 25 (b). Large defects corresponding to 312 missing pulses and 117 missing pulses were observed at two locations.

Example 3-1

Magnetic disks were produced in the same manner as in Example 1-1. The surface roughness Ra was 0.5 nm and the surface relief was 0.8 nm.

Thereafter, inspection of the bonds by the magnetic head was performed over the entire surface of this magnetic disk, after which the magnetic pattern was formed as follows.

The magnetic disk was installed on the magnetic pattern forming apparatus as shown in Fig. 3 and uniformly magnetized in the circumferential direction of the disk by applying an external magnetic field of 10 k Gauss. Thereafter, the external magnetic field applying means was changed to the structure of the apparatus shown in Fig. 4, and using substantially the same optical system as in Fig. 5, the excimer pulsed laser was irradiated to form a magnetic pattern.

After fixing the magnetic disk on the spindle, as shown in FIG. 18, it has radially formed lengths of 15 mm (radius: 15 mm to 30 mm) and transmission parts having a width of 1 μm every 45 °. Masks were placed on the magnetic disk with a space of about 10 μm and two were rotated at 2 rpm. The mask had a non-transmissive portions formed by a Cr layer having a thickness of 20 nm, and was a mask using quartz glass as the base material.

An excimer pulse laser having a wavelength of 248 nm was generated with a pulse width of 25 nsec using a power of 44 mJ / cm ² in a beam shape of 10 mm × 30 mm. The energy density (power) distribution of the beam was measured by a beam profiler manufactured by COHERENT Co., whereby the energy density distribution was about 30% in the short axis direction and in the long axis direction. About 10%. A three-split prism array with a focal length of 100 mm was placed in the laser irradiation aperture, and the laser was divided into three parts in the uniaxial direction, after which a power density of 80 mJ / cm ² and a beam shape of 5 mm x 30 mm were obtained. Were collected to get the beam with. The energy density distribution was suppressed at a level of about 10% in each of the short axis direction and the long axis direction.

Then, in order to print the magnetic pattern, the laser was repeatedly irradiated at a frequency of 1 Hz for 60 pulses through a shading substrate having fan-shaped transmissive portions at an angle of 6 ° while simultaneously generating a magnetic field of about 2.3 k Gauss. It was applied in the opposite direction to the uniform magnetization of.

The presence or absence of the formation of the magnetic pattern was confirmed by developing the magnetic pattern by a magnetic developer and observing it with an optical microscope. As a result, it was found that patterns corresponding to the transparent and non-transmissive portions of the mask were printed on the magnetic disk.

In addition, the magnetic pattern was reproduced by an MR head for a hard disk having a reproducing element width of 0.9 mu m, and the waveform was confirmed by an oscilloscope. The output of the observed waveform was the same as the output of the magnetic pattern recorded by the conventional magnetic head.

Thereafter, the change in output was measured over the entire circle at a position of 31.5 mm in the radial direction from the center of the disc, and it was known that it was in the range of ± 5% of the average value of the output, which was the case when recording was performed by the magnetic head. It was like

Example 3-2

Magnetic disks were produced in the same manner as in Example 3-1. Thereafter, investigation of defects was performed by the magnetic head over the entire surface of this magnetic disk, and then printing of the magnetic pattern was attempted in the same manner as in Example 3-1 except for the optical system.

A YAG-Q-switch fourth harmonic pulse laser having a wavelength of 266 nm was generated with a pulse width of 5 nsec, a power of 318 mJ / cm ² and a beam shape with a diameter of 8 mm. The energy density distribution was donut shaped and there was a high density portion along the outer side, with a distribution of 30%.

The laser was extended by a beam expander and then passed through an array of 21 split prisms to split the beam, after which the split beams were collected. Also, with the imaging lens, the length was extended three times only in the short axis direction to obtain a beam having a power of 73 mJ / cm ² and a beam shape of 12 mm × 36 mm. The energy density distribution was suppressed to about 10% in each of the short axis direction and the long axis direction.

Thereafter, in order to print the magnetic pattern, the laser was repeatedly irradiated at a frequency of 1 kHz for 30 pulses by placing a shading substrate having a fan-shaped transmissive portions having an angle of 12 ° and at the same time approximately 2.3 k Gauss. A magnetic field was applied in the direction opposite to the initial uniform magnetization.

The presence or absence of the formation of the magnetic pattern was confirmed, whereby it was found that the patterns corresponding to the transparent and non-transmissive portions of the mask were printed on the magnetic disk.

In addition, the magnetic pattern was reproduced by an MR head for a hard disk having a reproducing element width of 0.9 mu m, and the waveform was confirmed by an oscilloscope. The output of the observed waveform was the same as the output of the magnetic pattern recorded by the conventional magnetic head.

Thereafter, the change in output was measured over the entire circle at a position of 31.5 mm in the radial direction from the center of the disc, whereby the change in the output was found to be in the range of ± 5% of the average value of the output, which is recorded It was the same as if it was performed by the magnetic head.

Example 3-3

The magnetic head was manufactured in the same manner as in Example 3-1. Thereafter, inspection of the bonds by the magnetic head was performed over the entire surface of this magnetic disk, after which printing of the magnetic pattern was attempted. Example 3-1, except that the laser was irradiated repeatedly at a frequency of 1 kHz for 30 pulses through a shading substrate with a fan-shaped transmissive portion with an angle of 12 ° without using a three segment prism array for the optical system. The same conditions were used as in. That is, the pulse width was 25 nsec, the power was 44 mJ / cm ² , the beam shape was 10 mm × 30 mm, and the energy density distribution was about 30% in the short axis direction and about 10% in the major axis direction.

The presence or absence of the formation of the magnetic pattern was confirmed, thereby discovering that patterns corresponding to the transparent portions and the non-transparent portions of the mask were printed on the magnetic disk.

In addition, the magnetic pattern was reproduced by an MR head for a hard disk having a reproducing element width of 0.9 mu m, and the waveform was confirmed by an oscilloscope. The output of the observed waveform was the same as the output of the magnetic pattern recorded by the conventional magnetic head.

Thereafter, the change in output was measured over the entire circle at a position of 31.5 mm in the radial direction from the center of the disc, whereby the change was within ± 15% of the average value of the output, which was carried out by the magnetic head. Inferior to the case.

Example 4-1

Magnetic disks were produced in the same manner as in Example 1-1. Surface roughness Ra was 0.5 nm and surface relief Wa was 0.8 nm.

On the obtained disk, a magnetic pattern was formed as follows.

The magnetic disk was installed on the magnetic pattern forming apparatus as shown in Fig. 3, and was uniformly magnetized in the circumferential direction of the disk by applying an external magnetic field of 10 k Gauss. Thereafter, the external magnetic field applying means was changed to the structure of the apparatus as shown in FIG. 7, and the excimer pulsed laser was irradiated and a magnetic pattern was formed using the optical system shown in FIG.

In the optical system for pulse laser irradiation, an excimer pulse laser source having a wavelength of 248 nm was used as an energy beam source, and a pulse laser having a pulse width of 25 nsec and a beam diameter of 10 mm x 30 mm was emitted. One pulse was drawn by the programmable shutter and its intensity was adjusted by the attenuator so that the power on the magnetic disk was about 80 mJ / cm ² .

The beam is then concentrated so that the intensity distribution in the beam is uniform at the mask surface by a condensing lens composed of a combination of aspherical and plano-convex lenses having a diameter of 50 mm to obtain a patterned energy beam through the mask. It became.

28 shows a schematic of the mask used. Fig. 28 (a) shows the entire mask, and Fig. 28 (b) is an enlarged view of the mask area. The mask is made of quartz glass as the base material and the presence or absence of a Cr layer in which the recesses and protrusions (the protrusions correspond to the non-transmissive portions and the recesses correspond to the transmissive portions) has a thickness of about 20 nm. Is formed by. The mask has an inner diameter of 20 mm (radius: 10 mm) and an outer diameter (radius: 65 mm) of 130 mm, and the transmissive portions are in the range of 40 mm to 50 mm with a radial echo of angle θ in the range of 5 °. Patterned.

28 (b) shows an enlarged view. 300 transmissive parts are formed, which are made of long linear lines of radially enlarged 10 mm. The minimum width in the circumferential direction of the transparent portions and the non-transmissive portions is 4 μm.

By means of an imaging lens having a diameter of 20 mm and arranged so that the focal point of the condensing lens described above is centered, the patterning energy beam is reduced and projected to form a reduced image on the surface of the medium. The reduction ratio was 1/4. That is, the pattern on the mask was reduced to 1/4 in length and width, and projected from such a reduced image on the disk. At the same time, a magnetic field of about 1.5 k Gauss was applied by the permanent magnet in the direction opposite to the initial magnetization in the circumferential direction.

The magnetic pattern formed was evaluated by developing the magnetic pattern with a magnetic developer and observing it with an optical microscope. As a result, it was found that 300 magnetic patterns having a width of 1 μm were formed.

Example 4-2

A magnetic disk was produced in the same manner as in Example 4-1, after which the magnetic pattern was formed as follows.

The magnetic disk was installed on the magnetic pattern forming apparatus as shown in Fig. 3 and uniformly magnetized in the circumferential direction of the disk by applying an external magnetic field of 10 k Gauss. After that, the external magnetic field applying means was changed to the structure of the apparatus as shown in Fig. 7, and the excimer pulsed laser was irradiated by the optical system shown in Fig. 9 to form a magnetic pattern.

In the optical system for pulsed laser irradiation, a fourth harmonic YAG-Q-switched laser source having a wavelength of 266 nm was used as the energy beam source, and the beam was radiated with a pulse width of 5 nsec and a beam diameter of 8 mm. . One pulse was drawn by the programmable shutter, whose intensity was approximately 50 mJ / cm ² on the magnetic disk. It was adjusted by the attenuator so that Thereafter, the beam was enlarged to have a beam diameter of 24 mm by a triple beam expander.

Then, in order to obtain patterning energy beams through the mask, the beam is collected so that the intensity distribution in the beam is uniform on the mask surface by a condenser lens composed of a combination of a plano convex lens and an aspheric lens having a diameter of 50 mm. lost.

The mask used was substantially the same as that shown in FIG. 28, but the transmissive portions were patterned within the range covering angles θ = 15 ° and a radius of 40 mm to 48 mm. That is, 800 transmission parts made of 8 mm long linear lines were formed in the radial direction. The minimum width in the circumferential direction of the transparent portions and the non-transmissive portions was 4 μm.

The focusing lens of the above-mentioned condensing lens is placed at the center, and the patterning energy beam is reduced and projected by an imaging lens having a diameter of 20 mm to form a reduced image on the surface of the medium. The reduction ratio was 1/4. That is, the pattern on the mask was reduced and projected by 1/4 in length and width to form a reduced image on the disk. At the same time, a magnetic field of about 1.5 k Gauss was applied by the permanent magnet in the direction opposite to the initial magnetization in the circumferential direction.

The magnetic pattern formed was evaluated by developing the magnetic pattern with a magnetic developer and observing it with an optical microscope. As a result, it was found that 800 magnetic patterns having a width of 1 탆 were formed.

In addition, for the disks of Examples 4-1 and 4-2, the presence or absence of protective layer damage by laser irradiation was confirmed by measuring the peak intensities of graphite and diamond by Raman spectroscopy. If the protective layer is damaged by the laser, the peak intensity of the diamond decreases and the peak intensity of the graphite increases after laser irradiation. However, in this example, the peak ratios did not change compared to before and after irradiation.

In addition, for damages (decomposition, polymerization) of the lubricating layer, the presence or absence of damages was confirmed by measuring the average molecular weight number and the weight of the average molecular weight before and after laser irradiation, and no difference was also observed compared with before and after irradiation.

Applying the methods of the embodiments 4-1 and 4-2 to the formation of the servo pattern of the magnetic disk, it is possible to obtain a magnetic disk having a servo pattern with high precision simply and within a short period of time. In addition, using a magnetic disk device using such a magnetic disk, it is possible to perform tracking with high precision without having to rewrite the servo pattern or perform recording at high density.

Example 5-1

In addition to the preparation of the lubricating layer, a magnetic disk was produced in the same manner as in Example 1. Surface roughness Ra was 0.5 nm and surface relief Wa was 0.5 nm.

Fluorine lubricating layers were formed thereon by precipitation and withdrawing methods. Flon type solvent PF5060 by Ausimont Co. The solution prepared by diluting Fomblin-Z-DOL4000 prepared by was filled into the tank, and the disk was immersed in it. Thereafter, the solution was recovered at a rate of 10 liters / minute to form a lubricating layer. It was baked at 100 ° C. for 40 minutes and the thickness of the lubricating layer was measured by FT-IR to obtain 1.5 nm.

Thus, a horizontal recording magnetic disk having a coercive force of 30,000 Oe and a buried magnetization of 310 emu / cc at room temperature was obtained. The Curie temperature of the recording layer was 250 ° C.

Thereafter, inspection of the defects was performed by the magnetic head over the entire surface of this magnetic disk.

Thereafter, in order to form a magnetic pattern, a magnetic disk was fixed on the spindle, and then as shown in FIG. 18, a length of 15 mm (radius of 15 mm to 30 mm) radially formed every 45 ° and A mask with transmissive portions consisting of a width of 1 μm was formed on the magnetic disk at intervals of about 10 μm, and these two were rotated at 2 rpm. The mask was made of quartz glass as the base material and had non-transmissive portions formed by a Cr layer with a thickness of 20 nm.

On this disk, an excimer pulsed laser with a wavelength of 248 nm was irradiated through the mask. An excimer pulsed laser with a pulse width of 25 nsec, a power of 80 mJ / cm ² , and a beam diameter of 10 mm x 30 mm, is installed in the laser irradiation port by installing a fan-shaped shading substrate with an angle of 12 °. During the pulse, it was repeatedly irradiated at a frequency of 1 kHz, and at the same time a magnetic field of about 2.3 k Gauss was applied by the permanent magnet in the circumferential direction of the magnetic disk to print the magnetic pattern.

The magnetic pattern was developed by the magnetic developing device, and the presence or absence of the formation of the magnetic pattern was confirmed by observing this with an optical microscope. As a result, it was found that a pattern corresponding to the transparent and non-transmissive portions of the mask was printed on the magnetic disk.

Using FT-IR, the layer thickness of the lubricating layer was investigated and found to be reduced to 1.0 nm. During the rotation of the medium at 80 rpm, the same fluorine type lubrication layer was coated by a spin coater compared to the first, then dried at a rotational speed of 4,000 rpm, and the lubrication layer was recoated. After coating, the lubrication layer thickness was measured by FT-IR, which was obtained at 1.7 nm. This magnetic disk was CSS treated so that no head crush occurred until the 200,00th.

In addition, a magnetic pattern was formed on the magnetic disk under the same conditions, and the magnetic pattern was reproduced by an MR head for a hard disk having a reproducing element width of 0.9 mu m, and the waveform was confirmed by an oscilloscope. The output of the observed waveform was the same as the output of the magnetic pattern recorded by the conventional magnetic head.

Example 5-2

Magnetic disks were produced in the same manner as in Example 5-1. Thereafter, inspection of the defects was performed by the magnetic head over the entire surface of this magnetic disk.

Thereafter, by the ultrasonic cleaning apparatus, cleaning and removal of the lubricating layer were performed using a solvent that was used to dilute the lubricating layer. The film thickness of the lubricating layer was measured by FT-IT but no presence of the lubricating layer was found.

On this magnetic disk, printing of magnetic patterns was attempted in the same manner as in Example 5-1.

The presence or absence of the formation of the magnetic pattern was confirmed, whereby it was found that the patterns corresponding to the transparent and non-transmissive portions of the mask were printed on the magnetic disk.

Thereafter, during the rotation of the medium at 80 rpm, the same fluorine type lubrication layer was coated by a spin coater as compared to the beginning and spun at 4,000 rpm for drying, whereby the lubrication layer was recoated. After coating, the lubrication layer thickness was measured by FT-IT, which is known as 1.5 nm.

Further, under the same conditions, a magnetic pattern was formed on the magnetic disk, and reproduction was performed in the same manner as in Example 5-1, whereby the output of the observed waveform was recorded by the conventional magnetic head. Was the output of

Example 5-3

The magnetic disk was produced in the same manner as in Example 5-1 except that as a lubricating layer, the fluorine type lubricating layer was coated to a thickness of 0.7 nm by precipitation and recovery. A solution with Fomblin-Z-DOL4000 manufactured by Ausimont Co. diluted with Flon type solvent PF5060 was filled into the tank and the disc was immersed in it. Thereafter, the solution was recovered at a rate of 5 liters / minute to form a lubricating layer, which was baked at 100 ° C. for 40 minutes. Using FT-IR, the thickness of the lubricating layer was measured, which is known to be 0.7 nm.

Thereafter, inspection of the defects was performed by the magnetic head over the entire surface of this magnetic disk. Such 10,000 pieces of magnetic disk were produced.

In these magnetic disks, a magnetic pattern was formed continuously in the same manner as in Example 5-1. The same mask was used without changing the mask, but no contamination of the mask was observed. For the first piece, the 1000 piece, the 3000 piece, the 5000 piece and the 10,000 piece of disks, the following evaluation was performed.

The presence or absence of the formation of a magnetic pattern was confirmed, whereby it was found that for all the disks, patterns corresponding to the transparent and non-transmissive portions of the mask were printed on the magnetic disks.

Thereafter, during the rotation of the medium at 80 rpm, the same fluorine type lubricating layer was coated by a spin coater as compared to the beginning, and then rotated at 3,000 rpm for drying, whereby the lubricating layer was recoated. It became. After coating, the lubrication layer thickness was measured by FT-IT, which is known as 1.7 nm.

The formed magnetic pattern was reproduced by an MR head for a hard disk having a reproducing element width of 0.9 mu m, and the waveform was observed, and as a result, the output of the waveform was the same as the output of the magnetic pattern recorded by the normal magnetic head. In addition, a CSS test was performed so that no head crush occurred until the 200,000th.

Example 5-4

The magnetic disk was produced in the same manner as in Example 5-1 except that the lubrication layer was not formed. Thereafter, investigation of the defects was performed by the non-contact optical surface inspection apparatus over the entire surface of this magnetic disk.

10,000 pieces of such magnetic disks were made.

For these magnetic disks, a magnetic pattern was formed continuously in the same manner as in Example 5-1. The same mask was used without changing the mask but no stain of the mask was observed. For the first piece, the 1,000 piece, the 3,000 piece, the 5,000 piece and the 10,000 piece of discs, the following evaluation was performed.

The presence or absence of the formation of a metal pattern was confirmed, whereby it was found that for all the disks, patterns corresponding to the transparent and non-transmissive portions of the masks were printed on the magnetic disks.

Thereafter, the fluorine type lubricating layer was coated by precipitation and recovery and baked at 100 ° C. for 40 minutes. The lubrication layer thickness was measured by FT-IT, which is known as 1.5 nm.

The formed magnetic pattern was reproduced by an MR head for a hard disk having a reproducing element width of 0.9 mu m, and the waveform was confirmed by an oscilloscope. The output of the observed waveform was the same as the output of the magnetic pattern recorded by the conventional magnetic head. In addition, CSS tests were performed, but no head crash occurred until the 200,000th.

Example 5-5

Magnetic disks were produced in the same manner as in Example 5-1. Thereafter, inspection of the defects was performed by the magnetic head over the entire surface of this magnetic disk. For this magnetic disk, printing of the magnetic pattern was attempted in the same manner as in Example 5-1.

The presence or absence of the formation of a magnetic pattern was confirmed, whereby it was found that patterns corresponding to the transparent and non-transmissive portions of the mask were printed on the magnetic disk.

However, when the thickness of the lubricating layer was examined by FT-IT, it was known that it was reduced to 1.0 nm. This magnetic disk was CSS tested and head crushes occurred after 20,000 times. Since the free portion of the lubricating layer has disappeared, it is considered that durability has become insufficient.

Further, a magnetic pattern was formed on the magnetic disk under the same conditions, the magnetic pattern was reproduced by the MR head for hard disk having a reproducing element width of 0.9 mu m, and the waveform was confirmed by the oscilloscope. The output of the observed waveform was the same as the output of the magnetic pattern recorded by the conventional magnetic head.

Example 5-6

Magnetic disks were produced in the same manner as in Example 5-1. The thickness of the lubricating layer was 1.5 nm. Thereafter, inspection of the defects was performed by the magnetic head over the entire surface of this magnetic disk. 10,000 pieces of such magnetic disks were made.

For these magnetic disks, a magnetic pattern was formed continuously in the same manner as in Example 5-1. The same mask was used without changing the mask, whereby a precipitate began to be observed after about 3,000 pieces.

After completion of 10,000 pieces, the thickness of the precipitate on the mask was examined by FT-IT, which was known as 0.20 nm. The precipitate on the mask used for this printing was elementally analyzed by a secondary ion mass meter, whereby peak values of carbon and fluorine were detected, and the precipitate was found as a lubricating layer.

For the first piece, the 1,000 piece, the 3,000 piece, the 5,000 piece and the 10,000 piece of masks, the following evaluation was performed.

The presence or absence of the formation of a magnetic pattern was confirmed, whereby it was found that for all the disks, patterns corresponding to the transparent and non-transmissive portions of the mask were printed on the magnetic disks.

However, when the lubrication layer thickness was measured by FT-IT, it was known that the thickness was reduced to 1.0 nm. These magnetic disks were CSS tested and head crushes occurred after 20,000 times. Since the free portion of the lubricating layer was lost, the durability is considered to be insufficient.

The formed magnetic pattern was reproduced by an MR head for a hard disk having a reproducing element width of 0.9 mu m, and the waveform was confirmed by an oscilloscope. The output of the observed waveform was gradually reduced compared to the output of the magnetic pattern recorded by the magnetic head, which was 90% in the 3,000 pieces, 85% in the 5,000 pieces, and 80% in the 10,000 pieces. It is also known that the signal strength is reduced accordingly.

BRIEF DESCRIPTION OF THE DRAWINGS The figure explaining the example of the magnetic pattern formation method of this invention.

2 (a) to 2 (c) are diagrams illustrating still another example of the magnetic pattern forming method of the present invention.

Fig. 3A is a longitudinal sectional view of an example showing a portion to which a magnetic field is applied and a disk holding portion in the magnetic pattern forming apparatus of the present invention.

FIG. 3B is a view showing a portion to which a magnetic field is applied and a disk holding portion in the magnetic pattern forming apparatus shown in FIG.

4 is a longitudinal sectional view of an example showing a portion to which a magnetic field is applied and a disk holding portion in the magnetic pattern forming apparatus of the present invention;

5 shows an example of an optical system for irradiating an energy beam in accordance with the present invention.

6 shows an energy density distribution of an energy beam.

Fig. 7 is a longitudinal sectional view of an example showing a portion to which a magnetic field is applied and a disc holding portion to the magnetic pattern forming apparatus of the present invention.

8 shows an example of an optical system for irradiating an energy beam in accordance with the present invention.

9 illustrates another example of an optical system for irradiating an energy beam in accordance with the present invention.

10 is a diagram showing an example of a shading substrate used in the present invention.

Fig. 11 is a cross sectional view showing the structure of the main part of the disc according to the present invention;

Fig. 12 is a cross sectional view showing the structure of the main part of the disk according to the present invention;

Fig. 13 is a cross sectional view showing the structure of the main part of the disk according to the present invention;

Fig. 14 is a cross sectional view showing the structure of the main part of the disk according to the present invention;

Fig. 15 is a cross sectional view showing the structure of the main part of the disk according to the present invention;

Fig. 16 is a cross sectional view showing the structure of the main part of the disk according to the present invention;

17 is a diagram showing an example of a mask used in the embodiment of the present invention.

18 is a diagram showing another example of a mask used in the embodiment of the present invention.

19 is a diagram showing yet another example of a mask used in the embodiment of the present invention.

20 is a diagram showing an example of a magnetic pattern forming apparatus of the present invention.

21 is a diagram showing still another example of the magnetic pattern forming apparatus.

22 is a diagram showing still another example of the magnetic pattern forming apparatus.

23 shows an example of an optical system for irradiating a laser in accordance with the present invention.

24 (a) and 24 (b) show respective waveforms for reproducing signals in an embodiment of the present invention.

Fig. 24C is an enlarged photograph of the magnetic pattern obtained in the embodiment.

Figure 25 (a) Figure 25 (b) shows the evaluation results of the missing pulses in the example of the present invention.

Fig. 26 shows an enlarged photograph of the magnetic pattern obtained in the example of the present invention.

27 (a) to 27 (c) each show waveforms for reproducing signals in the example of the present invention.

28 (a) and 28 (b) show a mask used in the embodiment of the present invention.

29 is a view for explaining another example of an external magnetic field applying means.

30 is a view for explaining another example of an external magnetic field applying unit.

31 is a view for explaining another example of an external magnetic field applying means.

<Explanation of symbols for main parts of drawing>

101: magnetic disk 102: photomask

103: pulsed laser beam 104: external magnetic field

105: photopolymer 106: photo mask

107: objective light 108: prism

109: reference light 110; Laser light source

Claims (8)

A magnetic pattern forming apparatus for forming a magnetic pattern on a magnetic recording medium, A support device for supporting the magnetic recording medium; An external magnetic field source for applying an external magnetic field to the magnetic recording medium; An energy beam source that emits energy beams; A projection device for projecting and transmitting the energy beams from the energy beam source onto the magnetic recording medium; A mask positioned between the energy beam source and the magnetic recording medium and altering an intensity distribution of the energy beams in accordance with a desired magnetic pattern; And An intensity distribution disposed between the energy beam source and the projection device to equalize the spatial intensity distribution of the energy beams radiated from the energy beam source, dividing the energy beams into a plurality of portions and overlapping the divided portions Includes an equalizer, The projection apparatus includes an image forming apparatus positioned between the mask and the magnetic recording medium, and reduces the image size of the pattern of the intensity distribution of the energy beams to form a reduced image on the surface of the medium. . The method of claim 1, And the mask comprises a transmission portion for selectively transmitting a portion of the energy beams. The method of claim 1, And the energy beam source comprises a pulsed laser beam source. The method of claim 1, And the mask is disposed between the intensity distribution equalizer and the magnetic recording medium. delete The method of claim 1, And a condenser lens disposed between the energy beam source and the mask. The method of claim 1, And a cooling device for cooling the mask. A magnetic pattern forming apparatus for forming a magnetic pattern on a magnetic recording medium, Means for supporting the magnetic recording medium; Means for applying an external magnetic field to the magnetic recording medium; Means for radiating energy beams; Means for projecting and transmitting the energy beams from the radiating means onto the magnetic recording medium; Means for changing the intensity distribution of the energy beams in accordance with a desired magnetic pattern; And Means for equalizing the spatial intensity distribution of energy beams emitted from said radiating means, arranged between said radiating means and said means for transmitting and transmitting, said divided portion being divided into a plurality of portions Said equalizing means for superimposing them, The means for projecting and transmitting comprises an image forming apparatus positioned between the means for changing the intensity distribution and the magnetic recording medium, and reducing the image size of the pattern of the intensity distribution of the energy beams to reduce the image on the surface of the medium. Forming a magnetic pattern forming apparatus.

Images