JP2003098650A - Photomask, method of manufacturing the same and method of forming magnetized pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photomask formed with mask patterns with high accuracy. SOLUTION: The method of manufacturing the photomask having a process step of forming a photoresist layer on a transparent substrate element body 1 having a light shielding layer prior to an etching treatment, a process step of forming resist patterns on the light shielding layer by irradiating the photoresist layer with an energy ray to form latent image patterns, then developing the same, a process step of etching the light shielding layer, and a process step of removing the resist patterns, in which the transparent substrate element body 1 is rotated around its center and the energy ray is relatively moved in a diametral direction of the rotation of the transparent substrate element body and the transparent substrate element body is intermittently irradiated with the energy ray to be lined with the irradiation spots of the energy ray.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask manufacturing method, and more particularly to a photomask manufacturing method used for forming a magnetization pattern on a magnetic disk. The present invention also relates to a photomask manufactured by this method and a method for forming a magnetization pattern on a magnetic disk using this photomask.

[0002]

2. Description of the Related Art A magnetic recording device represented by a magnetic disk device (hard disk drive) is widely used as an external storage device of an information processing device such as a computer, and in recent years, it is a recording device for a moving image recording device or a set top box. It is also being used as a device.

A magnetic disk device usually has a shaft for fixing one or a plurality of magnetic disks in a skewered shape,
A motor for rotating a magnetic disk joined to the shaft through a bearing, a magnetic head used for recording and / or reproducing, an arm to which the head is attached, and a head for mounting the head on a magnetic recording medium. An actuator that can be moved to any position. The recording / reproducing head is usually a flying head, which moves on the magnetic recording medium with a constant flying height.

In addition to the flying head, in order to further reduce the distance to the medium, a contact head (contact head)
The use of is also suggested.

In a magnetic recording medium mounted on a magnetic disk device, a NiP layer is generally formed on the surface of a substrate made of an aluminum alloy or the like, and after performing a required smoothing treatment, texturing treatment, etc., a NiP layer is formed thereon. It is manufactured by sequentially forming a metal underlayer, a magnetic layer (information recording layer), a protective layer, a lubricating layer and the like. Alternatively, it is manufactured by sequentially forming a metal underlayer, a magnetic layer (information recording layer), a protective layer, a lubricating layer, etc. on the surface of a substrate made of glass or the like. The magnetic recording medium includes an in-plane magnetic recording medium and a perpendicular magnetic recording medium. Longitudinal recording is usually performed on the longitudinal magnetic recording medium.

The density of magnetic recording media is increasing every year, and there are various techniques for realizing this. For example, improvements such as making the flying height of the magnetic head smaller, adopting a GMR head as the magnetic head, and increasing the coercive force of the magnetic material used for the recording layer of the magnetic disk, and the information recording track of the magnetic disk Attempts have been made to reduce the interval between. For example, 100 Gb
To achieve it / inch ² , the track density is 10
0 ktpi or more is required.

A control magnetization pattern for controlling the magnetic head is formed on each track. For example, it is a signal used for position control of the magnetic head or a signal used for synchronization control. When the distance between the information recording tracks is narrowed and the number of tracks is increased, the signal used for position control of the data recording / reproducing head (hereinafter, also referred to as “servo signal”) is also aligned in the radial direction of the disk. On the other hand, it must be densely provided, that is, more, so that precise control can be performed.

In addition, it is desirable to increase the data recording capacity by reducing the area other than the area used for data recording, that is, the area used for servo signals and the gap between the servo area and the data recording area to widen the data recording area. Is also a big request. For this purpose, it is necessary to increase the output of the servo signal and the accuracy of the synchronization signal.

Conventionally, the method widely used for manufacturing is to make a hole in the vicinity of a head actuator of a drive (magnetic recording device), and insert a pin with an encoder into the hole.
The actuator is engaged with the pin, the head is driven to an accurate position, and the servo signal is recorded. However, since the center of gravity of the positioning mechanism and the center of gravity of the actuator are different from each other, highly accurate track position control cannot be performed, and it is difficult to accurately record the servo signal.

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

Therefore, a new servo signal forming method has been proposed.

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

In another example, the medium is magnetized in one direction in advance, a soft magnetic layer having a high magnetic permeability and a low coercive force is patterned on the master disk, and the master disk is brought into close contact with the medium and an external magnetic field is applied. Is the way. The soft magnetic layer acts as a shield, and the magnetization pattern is transferred to the unshielded region (Japanese Patent Laid-Open No. 60-60212 (USP 3,869,711), Japanese Patent Laid-Open No. 10-40).
544 (EP915456), Digest of Inte
rMag 2000, GP-06, see).

In each of these methods, a master disk is used and a magnetic pattern is formed on the medium by a strong magnetic field.

Generally, the strength of the magnetic field depends on the distance.
When recording a magnetization pattern with a magnetic field, the leakage magnetic field tends to obscure the pattern boundaries. Therefore,
Intimate contact between the master disk and the medium is essential to minimize stray magnetic fields. Further, as the pattern becomes finer, it is necessary to completely adhere to each other without a gap, and usually, both are pressure-bonded by vacuum suction or the like.

Also, the higher the coercive force of the medium, the larger the magnetic field used for transfer and the larger the leakage magnetic field.
Furthermore, it is necessary to make them adhere completely.

Therefore, the above technique is easily applied to a magnetic disk having a low coercive force and a flexible floppy (registered trademark) disk which is easily adhered to a master disk, but it is used for high density recording using a hard substrate. It is very difficult to apply to a magnetic disk having a coercive force of 3000 Oe or more.

In other words, the magnetic disk of the hard substrate has a risk that minute dust or the like may be caught in the medium when it comes into close contact with the master disk, or the expensive master disk may be damaged. In particular, in the case of a glass substrate, there are problems that the adhesion is insufficient due to the inclusion of dust, magnetic transfer cannot be performed, and cracks occur in the magnetic recording medium.

Further, Japanese Patent Laid-Open No. 60-60212 (USP
3, 869, 711),
The pattern having an oblique angle with respect to the track direction of the disk has a problem that only a pattern having weak signal strength can be formed although recording is possible. Coercive force is 2000 ~
For a magnetic recording medium having a high coercive force of 2500 Oe or more, in order to secure the magnetic field strength for transfer, the pattern ferromagnetic material (shield material) of the master disk is made of soft magnetic material such as permalloy or sendust having a large saturation magnetic flux density. I have no choice but to use my body.

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

In order to solve such a problem, the present applicant has filed Japanese Patent Application Nos. 2000-134608 and 200.
No. 0-134611 proposes a method of forming a magnetization pattern on a magnetic recording medium by combining local heating and application of an external magnetic field. For example, the medium is magnetized in one direction in advance, and an energy ray is irradiated through a patterned mask to locally heat the medium, and an external magnetic field is applied while lowering the coercive force of the heated region. Magnetization is applied by an external magnetic field to form a magnetization pattern.

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

Further, since it is not necessary to shield the external magnetic field by the soft magnetic material of the master disk, a diagonal magnetization pattern can be formed well.

In the method of irradiating an energy ray through such a photomask to locally heat the magnetic layer and applying an external magnetic field to form a magnetization pattern, a laser beam is mainly used as an energy ray at present. It is used. In addition, a light shielding layer is formed on the photomask in a pattern that matches the magnetization pattern to be formed.
Incidentally, as this photomask, a photomask in which a chromium-based light-shielding layer is formed on a transparent substrate made of quartz glass is mainly used. The chrome-based light-shielding layer is mainly composed of a metal chrome layer only; or a chrome oxide layer formed on the surface of a metal chrome layer.

A method of forming this photomask will be briefly described below.

As the transparent substrate body, a transparent substrate made of quartz glass and a light-shielding layer uniformly formed on one surface thereof is used.

A photoresist containing a photo-curable resin is applied on the transparent substrate body to a predetermined thickness and baked if necessary.

The photoresist is irradiated with a laser beam to form a latent image pattern. This latent image pattern is a pattern that matches the light-shielding layer pattern (mask pattern) to be formed.

A developing solution is supplied onto this substrate to remove the photoresist in the exposed portion, and then, if necessary, baking is performed to form a resist pattern.

Then, the light shielding layer is etched, and finally,
The remaining resist pattern is dissolved and removed (removed).
As a result, a photomask having a light shielding layer pattern (mask pattern) formed on a transparent substrate is manufactured.

Conventionally, the above-mentioned exposure is performed by moving the laser beam irradiator in the XY direction by the XY moving device.

[0032]

When the laser beam irradiator is moved in the XY direction by the XY moving device, the irradiator is moved in two directions, the X direction and the Y direction, so that the positional accuracy of the irradiator is low. It is easy to become. If the moving speed is decreased to increase the positional accuracy of the irradiator, the manufacturing efficiency of the photomask decreases in proportion to the decrease in the moving speed.

The present invention provides a photomask manufacturing method capable of efficiently manufacturing a photomask having a highly accurate mask pattern, a photomask manufactured by this method, and a magnetization pattern using this photomask. And a forming method.

[0034]

A method of manufacturing a photomask of the present invention is a method of manufacturing a photomask in which a light shielding layer is formed in a predetermined pattern on a transparent substrate by etching, and the light shielding layer before etching treatment is used. A step of forming a photoresist layer on a transparent substrate element provided with a layer, and forming a latent image pattern according to the pattern by irradiating the photoresist layer with energy rays from an energy ray irradiator, and then developing. A step of forming a resist pattern on the light-shielding layer, a step of etching the light-shielding layer, a step of removing the resist pattern, and a method of manufacturing a photomask having a transparent substrate element on which a photoresist layer is formed. The energy beam irradiator is rotated about the center to move the energy beam irradiator relatively in the radial direction of rotation of the transparent substrate element, and at the same time, energy is intermittently applied. Irradiating the, it is characterized in that to form the latent image pattern by contiguous with spot by irradiation of the energy beam.

In the photomask manufacturing method of the present invention, the energy beam irradiator is relatively moved only in the radial direction (r direction) of the transparent substrate body, whereby the energy beam irradiation spot is moved in the r direction. Positioning is done. Since this movement is a one-dimensional movement, the positioning accuracy is extremely high as compared with the case of XY movement (two-dimensional movement).

Positioning of the irradiation spot of the energy beam in the circumferential direction (θ direction) is performed by controlling the timing of energy beam irradiation from the irradiator while synchronizing with the rotation of the transparent substrate body. Since the timing of this energy ray irradiation is performed with high accuracy by a modulator or the like, the positional accuracy of the irradiation spot in the θ direction is also extremely accurate.

As described above, according to the present invention, the position of the energy beam irradiation spot is controlled by the r-θ method, and a photomask having a highly accurate mask pattern can be manufactured. Further, even if the moving speed of the irradiator in the r direction or the rotating speed in the θ direction is increased, the accuracy of the mask pattern can be sufficiently increased. Therefore, according to the present invention, the manufacturing efficiency of the photomask is remarkably high. Becomes

The photomask of the present invention is manufactured by the method for manufacturing a photomask of the present invention.

According to the method of forming a magnetic pattern in a magnetic disk of the present invention, the magnetic disk having a magnetic layer is irradiated with an energy ray through a photomask, whereby the magnetic layer is locally heated and externally irradiated. In a method of applying a magnetic field to form a magnetization pattern, the photomask manufactured by the method of the present invention is used as the photomask.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a photomask of the present invention is a method for producing a photomask in which a light-shielding layer is formed in a predetermined pattern on a transparent substrate by etching. A step of forming a photoresist layer on the provided transparent substrate element, and a latent image pattern according to the above pattern is formed by irradiating the photoresist layer with an energy ray from an energy ray irradiator, followed by development and shading. In a method for manufacturing a photomask, which comprises a step of forming a resist pattern on a layer, a step of etching a light-shielding layer, and a step of removing the resist pattern, a transparent substrate element on which a photoresist layer is formed is the center. The energy beam irradiator is rotated relative to the radial direction of the transparent substrate body and the energy beam is intermittently irradiated. And it is characterized in that to form the latent image pattern by contiguous with spot by irradiation of the energy beam.

The transparent substrate is preferably a transparent quartz substrate,
It is not limited to this. The shape of the transparent substrate is arbitrary and may be square or circular.

The light-shielding layer formed on the transparent substrate is preferably a metal chromium film or a film in which a chromium oxide layer is formed on the surface of the metal chromium film, but not limited to this.

The exposure process of the photomask manufacturing method according to the embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an exposure apparatus of a photomask manufacturing method according to an embodiment, and FIGS. 2 and 3 are schematic explanatory diagrams showing overlapping states of irradiation spots.

As shown in FIG. 1, a transparent substrate body 1 with a photoresist is placed on a turntable 10, and the turntable 10 is rotated at a constant speed. The transparent substrate body 1 includes a transparent substrate made of quartz glass and a light-shielding layer uniformly formed on the upper surface of the transparent substrate. A photoresist is applied on this light shielding layer.

With respect to the photoresist on the transparent substrate body 1, the laser beam from the light source 20 is supplied with a power control EOM (electro-optical modulator) 21, a corner mirror 22, an ON / OFF control EOM 23, a corner mirror 24, Irradiation is performed via the beam expander 25, the epi-illumination mirror 26, and the objective lens 27. The incident mirror 26 and the objective lens 27 constitute a laser beam irradiator. The epi-illumination mirror 26 and the objective lens 27 are mounted on a slider 30 and are moved in the radial direction with respect to the rotation center of the turntable 10. The objective lens 27 is focus-controlled so that the irradiation spot is focused on the transparent substrate body 1 placed on the turntable 10.

The epi-reflecting mirror 26 and the objective lens 27 are moved in the radial direction, and the spot of the laser beam emitted from the objective lens 27 is intermittently irradiated on the photoresist on the transparent substrate body 1 to form a continuous spot. As a result, a latent image pattern is formed.

This epi-illumination mirror 26 and objective lens 27
May be stepwise moved in the radial direction at a predetermined pitch p, or may be continuously moved in the radial direction, so these will be described individually below.

[Step Moving Method] A method of moving the epi-illumination mirror 26 and the objective lens 27 at a predetermined pitch in the radial direction to connect the spots will be described with reference to FIG.
It should be noted that FIG. 2 is a schematic view, and the spots are markedly enlarged and markedly huge. Further, although only four spots are illustrated in the circumferential direction, the present invention is not limited to this.

First, in order to form the innermost side of the mask pattern, the epi-illumination mirror 26 and the objective lens 27 are positioned on the rotation center side of the transparent substrate body 1 and stopped. The transparent substrate body is rotated at a constant speed. A laser beam is irradiated a plurality of times at a predetermined time for a predetermined time during one rotation of the transparent substrate body. As a result, the irradiation spot S ₁ on the innermost peripheral side is formed on the photoresist 2 of the transparent substrate body 1. Each irradiation spot S ₁ has an arcuate shape extending on the equiradial position in the rotation circumferential direction.

The radial width of the irradiation spot S ₁ is determined by the beam diameter of the laser beam, and the circumferential length is determined by the irradiation time of the laser beam and the substrate rotation speed. The circumferential position of the spot is determined by the irradiation timing of the laser beam.

1 transparent substrate body 1 with photoresist
After forming each spot S ₁ during the rotation, the epi-illumination mirror 26 and the objective lens 27 are moved in the radial direction (radial direction with respect to the rotation center in this case) by a predetermined pitch p (note that during this movement as well). The transparent substrate body is rotating at a constant speed.) Then, again, while the transparent substrate body 1 makes one rotation, the laser beam is irradiated a plurality of times at a predetermined timing for a predetermined time to form each spot S ₂ on the second circumference. This spot S ₂ partially overlaps with the spot S ₁ .

After forming each spot S ₂ , the epi-reflecting mirror 26 and the objective lens 27 are radially moved by the pitch p and the same irradiation as above is performed to form each spot S ₃ on the third circumference. To do. After that, the same procedure is repeated to form the outermost peripheral spot, thereby completing the exposure process.

[Continuous Moving Method] A method of forming each spot S ₁ , S ₂ , S ₃ ... While continuously moving the epi-illumination mirror 26 and the objective lens 27 in the radial direction will be described with reference to FIG. .

First, the incident mirror 26 and the objective lens 27.
Is placed at the mask pattern formation start position on the center side of the transparent substrate body 1 with the photoresist. Transparent substrate body 1
Is rotated at a constant speed. While moving the epi-illumination mirror 26 and the objective lens 27 in the radial direction at a constant minute speed,
While the transparent substrate body 1 makes one revolution, the laser beam is irradiated a plurality of times at a predetermined timing for a predetermined time to form a plurality of irradiation spots S1 on the innermost peripheral side. The radial width of each irradiation spot S ₁ is determined by the beam diameter of the laser beam, and the circumferential length is determined by the irradiation time and the substrate rotation speed. In the case of FIG. 3, each spot S ₁ extends in a spiral direction oblique to the circumferential direction of equal radius. The angle of this crossing is determined by the rotation speed of the transparent substrate body 1 and the incident light mirror 2
6 and the radial movement speed of the objective lens 27.

The radial movement speed of the epi-illumination mirror 26 and the objective lens 27 is the speed at which the epi-illumination mirror 26 and the objective lens 27 move by the predetermined pitch p while the transparent substrate body makes one rotation.

[0056] After each spot S ₁ of the transparent substrate body 1 is the innermost periphery is rotated 1 is formed, each spot S ₂ of the second circumferential surface during rotation 1 subsequent transparent substrate film element body 1 Form.
Each spot S ₂ partially overlaps each spot S ₁ . Each subsequent spot S ₃ of the third week is formed during one rotation of the transparent substrate body 1 in the third rotation, and the spots on the outermost periphery are formed in the same manner, whereby the exposure step is completed. To do.

After the completion of this exposure, the steps of development, post-baking, etching and remove are carried out, but these steps are not particularly limited, and various methods such as the same methods as conventional ones can be adopted.

In FIGS. 2 and 3, the spots are formed in order from the inner peripheral side to the outer peripheral side, but this may be reversed.

Detailed conditions or preferable conditions of the exposure process shown in FIGS. 2 and 3 or other constitutions that can be adopted will be described below.

Although the laser beam is used as the energy beam in the above description, it may be another energy beam such as an electron beam. The laser beam is Ar
In addition to lasers and Kr lasers, various types such as YAG quarter-waves can be used. Although EOM is used for laser modulation, in the case of an electron beam, an electromagnetic system deflection / modulation device may be used.

The radial moving speed of the beam is 20 μm / s.
If it is ec or less, the mask pattern can be formed with extremely high accuracy.

The rotating speed of the transparent substrate body 1 can be 1.25 m / sec or more as the peripheral speed, and 11.31 m / sec or more if the control response such as EOM is secured. This is 1000 times or more as high as the moving speed (10 mm / sec or less) of the current XY moving device.

The energy beam may have a circular shape, an elliptical shape, or the like.

The maximum energy density of the circular beam is 1
Assuming that the diameter of / e ² is 0.82 (λ / NA), that is, the beam diameter is d, the ratio p / d between the pitch p and the beam diameter d is as shown in FIG. In the case of 0.
5 to 0.9, especially 0.5 to 0.75, especially 0.6 to 0.
It is preferable to set the pitch p to be 75. With p / d in this range, the overlap between adjacent irradiation spots becomes appropriate, and the spots S ₁ , S ₂ ,
The edges of the latent image pattern formed by S ₃ ... And the mask pattern formed based on the latent image pattern are smoothly continuous lines. When p / d is larger than 0.9, the unevenness of the edge may be larger than the allowable value. If p / d is less than 0.5, the edge will be very smooth, but the exposure time will be longer.

When the beam is elliptical, it is preferable to set the pitch p so that the diameter of the ellipse in the radial direction of the transparent substrate body satisfies the above condition of p / d. Note that p / d is
It is preferably set according to the γ value of the photoresist.

In the above embodiment, one laser beam is emitted, but as shown in FIG. 4, a plurality of (n) laser beams are arranged in the radial direction or substantially in the radial direction to form a group of laser beams. Beam, and this group of laser beams is integrated into n ×
It may be moved in the radial direction at a pitch of p. The same applies to other energy rays such as electron rays. By doing so, the exposure time can be shortened to about 1 / n as compared with the case of performing exposure with one laser beam.

In this case, a group of laser beams is formed.
The degree of overlap between the laser beams₁，
S_Two, S_ThreeIt is preferable to make it similar to the degree of overlap between each other.
Yes. For example, as shown in FIG. 4, one group is formed by two laser beams.
When constructing a laser beam of
Beam diameter is d₁, The beam diameter of the other laser beam is d _Two
And the distance between the centers of both laser beams is L
L / [(d₁+ D_Two) / 2] is particularly 0.5 to 0.9
0.5 to 0.75, especially 0.6 to 0.75
Is preferably set to L.

A method of forming a magnetization pattern on a magnetic disk (magnetic recording medium) using the photomask thus manufactured will be described with reference to FIGS. 5A is a plan view showing a method of forming a magnetization pattern according to the embodiment, FIG. 5B is a sectional view taken along line BB of FIG. 5A, and FIG. 6 is a schematic view showing magnetic flux. FIG. 7 is an enlarged sectional view of the magnetic recording medium.

In this magnetization pattern forming method, as shown in FIG. 7, an in-plane magnetic recording having a magnetic layer 41b on a substrate 41a, and the magnetic layer 41b being magnetized substantially uniformly in a predetermined direction within the plane. As shown in FIG. 5 (b), the medium 41 is irradiated with energy rays 45 to locally heat the magnetic layer 41b, and at the same time, an external magnetic field is applied to the magnetic layer 41b using a magnet 42 so that the heating portion is moved in the predetermined direction. A magnetization pattern is formed by magnetizing in the opposite direction. The magnetic recording medium 41 is placed and fastened on a turntable (not shown).

The light shielding plate 43 is used to limit the irradiation area of the energy rays 45. Energy ray 45
Passes through the fan-shaped window hole 43a of the light shielding plate 43, further passes through the photomask 44, and is irradiated onto the magnetic recording medium 1.

The magnet 42 has an N pole (reference numeral N in the figure).
And S pole (symbol S in the figure). This magnet 4
2 are arranged on both surface sides (upper and lower sides in FIG. 5B) of the disk-shaped magnetic recording medium 41. The magnetic flux from the N pole of the upper magnet 42 to the S pole and the N of the lower magnet 42
The magnetic flux from the pole to the S pole cancels out vertical components in the magnetic layer 41b, and only the in-plane component is magnetic layer 41b.
applied to b. As a result, the magnetic layer 41b comes to be magnetized in the in-plane direction. A top yoke 46 is arranged at the end of each magnet 42 near the center of the magnetic recording medium 1. This is to compensate for the weakening of the magnetic field near the end.

Although not shown, the photomask 44 has
A light-shielding layer pattern matching the magnetization pattern to be formed is formed by the method of the present invention. A spacer 47 is interposed between the mask 44 and the magnetic recording medium 41.

While rotating the magnetic recording medium 41 uniformly magnetized in a predetermined direction, the magnetic recording medium 41 is locally heated by irradiating with the energy rays 45, and the magnetic recording medium 41 is heated by the magnetic flux from the magnet 42. Magnetization is performed in the inward direction according to the pattern in the opposite direction to the predetermined direction to form a magnetization pattern.

In this magnetization pattern forming method, preferably, a pattern forming process is performed on a magnetic recording medium which is magnetized uniformly in a predetermined direction (for example, the circumferential direction). A method of previously magnetizing the magnetic recording medium uniformly in a predetermined direction is arbitrary. Usually, the magnetic recording medium immediately after manufacturing is randomly magnetized, so it is preferable to uniformly magnetize it with another external magnetic field.

As a means for applying this external magnetic field, a magnetic head may be used, or an electromagnet or a permanent magnet may be arranged so as to generate a magnetic field in a desired magnetization direction. You may use two or more. Furthermore, these different means may be used in combination.

The predetermined direction is the same as or opposite to the running direction of the data write / playback head (the relative movement direction of the medium and the head). In a disk-shaped magnetic recording medium, it is usually in the circumferential direction of the medium. Therefore, an external magnetic field is applied so as to be magnetized as such.

Further, to uniformly magnetize the entire magnetic layer in a desired direction means to magnetize all the magnetic layers in substantially the same direction, but not exactly all, and at least form the magnetization pattern of the medium. It suffices that the regions to be magnetized are magnetized in the same direction.

Although the strength of this magnetic field varies depending on the characteristics of the magnetic layer of the magnetic recording medium, it depends on the coercive force of the magnetic layer at room temperature, which is 2
It is preferable to magnetize by a magnetic field more than double. If it is weaker than this, the magnetization may be insufficient. The upper limit of this magnetic field is about 5 times or less the coercive force of the magnetic layer at room temperature.

In the method for forming a magnetic pattern according to the present invention, after the magnetic layer is magnetized uniformly in a predetermined direction in this way, the magnetic layer is locally heated and at the same time an external magnetic field is applied to the heating portion so that the heating portion has the predetermined direction. Magnetize in the direction opposite to the direction to form a magnetization pattern. According to this, magnetic domains in opposite directions are clearly formed, so that the signal strength is high and C / N and S are high.
A magnetization pattern with a good / N is obtained.

When the magnetic recording medium is irradiated with energy rays and heated, the heating temperature is equal to or higher than the temperature at which the coercive force of the magnetic layer is lowered, for example, near the magnetization disappearing temperature of the magnetic layer and the Curie temperature. In the present invention, it is preferable to use a magnetic recording medium whose temperature is 100 ° C. or higher. A magnetic recording medium whose temperature is lower than 100 ° C. tends to have low stability of magnetic domains at room temperature. The heating temperature is preferably 700 ° C or lower. If the heating temperature is too high, the magnetic recording medium may be deformed.

The direction of the magnetic field applied simultaneously with the heating is opposite to the direction of the above-mentioned uniform magnetization. Also, the stronger the magnetic field, the easier the formation of the magnetization pattern. Preferably, the magnetic field strength in the in-plane direction is 1/8 of the coercive force of the magnetic layer at room temperature.
The above magnetic field is used. If it is weaker than this, when the heating part is cooled, it may be magnetized again in the same direction as the surroundings under the influence of the magnetic field from the surrounding magnetic domains.

However, if the applied magnetic field at the time of heating is too strong, the magnetic domains around the heating portion may be affected. Therefore, the magnetic field strength applied to the heating region is preferably such that the magnetic field strength in the in-plane direction is smaller than the coercive force of the magnetic layer at room temperature, and particularly 2/3 or less of the coercive force of the magnetic layer at room temperature, especially 1 / It is preferably 2 or less.

In order to achieve the above magnetic field distribution, an external magnetic field is applied by arranging magnets 42 (magnet pairs) having magnetic poles opposite to each other on both sides of the magnetic recording medium 41 as shown in FIG. Is preferred. According to this method, as shown in FIG. 6, the magnetic field strength applied in the in-plane direction of the magnetic recording medium 1 is twice the in-plane direction component of the magnetic field applied from one magnet pair, and the vertical components cancel each other out. . This makes it possible to reduce the vertical component and increase only the in-plane direction component.

The vertical component can be remarkably reduced by optimizing the strength and distance of the magnet.

Next, the irradiation mechanism of the energy ray 45 for locally heating the magnetic layer will be described.

As the energy ray, it is preferable to use a laser which can easily prevent heat diffusion to an unnecessary portion and control the power and can easily control the size of a portion to be heated.

Further, it is preferable that the laser is pulsed rather than continuous irradiation to control the heating portion and the heating temperature. Therefore, it is preferable to use a pulsed laser light source as the laser irradiation source. A pulsed laser light source oscillates a laser in a pulsed manner intermittently, and compared with a continuous laser that is intermittently pulsed by an optical component such as an acousto-optic device (AO) or an electro-optic device (EO), It is possible to irradiate a laser having a high power peak value in a very short time, and it is very preferable that heat is hardly accumulated.

When a continuous laser is pulsed by optical components, it has almost the same power within the pulse over its pulse width. On the other hand, the pulsed laser light source accumulates energy by resonance in the light source, for example, and emits the laser as a pulse at a time. Therefore, the power of the peak is very large in the pulse and then becomes small. A pulsed laser light source can be used to heat rapidly in a very short period of time and then cool rapidly. This makes it possible to form a highly accurate magnetic pattern with high contrast.

The medium surface on which the magnetization pattern is formed has a larger temperature difference between the irradiation of the pulsed laser and the non-irradiation of the pulsed laser.
It is preferable to increase the contrast of the pattern or increase the recording density. Therefore, it is preferable that the temperature is about room temperature or lower when the pulsed laser is not irradiated. What is room temperature 2
It is about 5 ° C.

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

The wavelength of the laser is preferably 1100 nm or less. When the wavelength is shorter than 1100 nm, the diffraction effect is small and the resolution is improved, so that a fine magnetization pattern is easily formed. Laser light with a wavelength of 600 nm or less
Not only the resolution is high, but also the diffraction is small, so that the spacing between the mask and the magnetic recording medium can be widely taken due to the gap, and the handling is easy, and the magnetization pattern forming device can be easily configured. In addition, the wavelength of the laser light is preferably 150 nm or more. 150n
If it is less than m, the absorption of synthetic quartz used for the mask becomes large, and heating tends to be insufficient. If the wavelength is 350 nm or more, the optical glass can be used as a mask.

The laser light is specifically an excimer laser (157, 193, 248, 308, 351n).
m), 2 of YAG Q-switched laser (1064 nm)
Overtone (532nm), Overtone (355nm), or 4
Harmonics (266nm), Ar laser (488nm, 514nm)
nm), ruby laser (694 nm), etc. are suitable.

The power of the laser (irradiation energy per unit area) may be selected as an optimum value depending on the magnitude of the external magnetic field, but the power per pulse of the pulsed laser is 1000 mJ / cm ² or less. preferable. If a power higher than this is applied, the pulsed laser may damage the surface of the magnetic recording medium and cause deformation. If the roughness Ra increases to 3 nm or more and the waviness Wa increases to 5 nm or more due to the deformation, the running of the flying / contact type head may be hindered.

The laser power is more preferably 500.
mJ / cm ² or less, more preferably 200 mJ /
It is not more than cm ² . In this region, it is easy to form a magnetization pattern with high resolution even when a substrate having a relatively large thermal diffusion is used. The power is preferably 10 mJ / cm ² or more. If it is smaller than this, the temperature of the magnetic layer is hard to rise and magnetic transfer is hard to occur. Note that the required power tends to increase as the pattern width becomes narrower. Further, the shorter the wavelength of the laser, the lower the upper limit of the power that can be applied tends to decrease.

When the substrate of the magnetic recording medium is a metal such as Al or an alloy, the heat conductivity is large, so that the heat applied locally spreads to other than the desired portion and the magnetization pattern is distorted. The power is preferably in the range of 30 to 120 mJ / cm ² so that there is no physical damage to the substrate due to excess energy.

When the substrate of the magnetic recording medium is a ceramic such as glass, the heat conduction is less than that of Al and the heat is accumulated much at the pulsed laser irradiation site, and therefore the power is 10 to 100 mJ / It is preferably in the range of cm ² .

When the substrate of the magnetic recording medium is a resin such as polycarbonate, the power is 10 to 80 mJ / cm because the heat of the pulsed laser irradiation is large and the melting point is lower than that of glass. It is preferably in the range of ² .

If the magnetic layer, the protective layer, and the lubricating layer may be damaged by the laser, the power of the pulsed laser may be reduced to increase the strength of the applied magnetic field. For example, in the case of an in-plane recording medium, the coercive force at room temperature is 25 to 7
A magnetic field as large as possible of 5% is applied to reduce the power of the irradiation laser.

When the pulsed laser is irradiated through the protective layer and the lubricating layer, it may be necessary to re-apply after the irradiation in consideration of damage (decomposition, polymerization) to the lubricant.

The pulse width of the pulsed laser is 1 μsec.
The following is desirable. If the pulse width is wider than this, the heat generated by the energy given to the magnetic recording medium by the pulsed laser is dispersed, and the resolution is likely to be lowered. When the power per pulse is the same, when the pulse width is shortened and a strong laser is irradiated at one time, thermal diffusion tends to be small and the resolution of the magnetization pattern tends to be high. It is more preferably 100 nsec or less. In this region, it is easy to form a magnetization pattern with high resolution even when a substrate such as Al having a relatively large thermal diffusion is used. Minimum width is 2μ
When forming a pattern of m or less, a pulse width of 25n
It is better to be less than sec. That is, if the resolution is important, the shorter the pulse width, the better. The pulse width is 1 ns
It is preferably ec or more. This is because it is preferable to keep heating for the time until the magnetization reversal of the magnetic layer is completed. In the present application, the minimum width of the pattern means the narrowest length of the pattern. A square pattern has a short side, a circle has a diameter, and an ellipse has a short diameter.

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

In the present invention, by irradiating an energy ray through a mask and heating locally, it is possible to easily form a complicated pattern or a special pattern which is difficult to make by the conventional method.

For example, in the phase servo system of the magnetic recording medium, a magnetization pattern extending linearly obliquely to the radius and the track from the inner circumference to the outer circumference is used. Such a pattern continuous in the radial direction or a pattern oblique to the radius has been difficult to form by the conventional servo pattern forming method of recording a servo signal track by track while rotating the disk. According to the magnetization pattern forming method of the present invention,
Such a magnetization pattern can be formed easily and in a short time with a single irradiation, without requiring complicated calculations and complicated device configurations.

The photomask does not have to cover the entire surface of the magnetic disk, but may have a size including a repeating unit of the magnetization pattern. In the latter case, it is moved and used.

When the magnetic disk is provided with a lubricating layer before the formation of the magnetization pattern, a spacer is arranged between the mask and the medium in order to minimize the adhesion of the lubricant to the photomask. It is preferable to provide a gap.

FIG. 8 is an explanatory diagram of the magnetic pattern of the magnetic recording medium 80 on which the magnetic pattern 81 is formed by this magnetic pattern forming method. As shown in (a), the disk-shaped magnetic recording medium 80 is provided with hundreds and dozens of arc-shaped magnetization patterns 81 extending substantially in the radial direction. Each magnetization pattern 81 has a plurality of preambles 82 extending in the arc direction and a zigzag pattern 83 arranged along the preambles 82, as shown in FIG. Although not shown, another pattern may be provided. Each of the preamble 82 and the zigzag pattern 83 has a line width of about 1 to 2 μm. The magnetization directions of the preamble 82 and the zigzag pattern 83 of FIG. 8B are from left to right in the figure, and the magnetization directions of the other magnetic layers are from right to left. Such a fine pattern can also be formed into a magnetization pattern with high efficiency by using the photomask.

[0107]

EXAMPLES Examples and comparative examples will be described below.

Example 1 A transparent substrate body in which a 80-nm-thick metallic chromium layer was uniformly formed on a quartz transparent substrate having a thickness of 2.3 mm and a side of 127 mm was coated with a photoresist by spin coating. It was coated to a thickness (dry thickness) of 200 nm. Kr laser (λ = 413 mm) was used for NA = 0.
9, irradiation with the beam diameter d = 0.38 μm was carried out by the method of FIG. 2, and post-baking, development and removal were performed to manufacture a photomask having 180 arc-shaped mask patterns as shown in FIG.

In this embodiment, the radial feed pitch p is 0.2 μm and p / d = 0.52.

As a result, the edges of the mask pattern were smooth.

Photomasks were manufactured in the same manner as in Example 1 except that Example 2 and Comparative Examples 1 and 2 were as follows. Example 2: p = 0.30 μm (p / d = 0.79) Comparative example 1: p = 0.35 μm (p / d = 0.92) Comparative example 2: p = 0.5 μm (p / d = 1.31)

As a result, in Example 2, some irregularities were found at the edges of the pattern, but they were within the allowable range. On the other hand, in Comparative Example 1, large irregularities were generated at the edges of the pattern, and in Comparative Example 2, the pattern was not continuous and each spot was discrete.

Further, magnetic disks were manufactured using the photomasks of Examples 1 and 2 and Comparative Examples 1 and 2, and timing asymmetry was measured. The result is shown in FIG.

In the signal when the magnetic pattern on the magnetic recording medium is reproduced by the magnetic head, the ratio of the time from the positive direction pulse to the negative direction pulse to the time from the positive direction pulse to the positive direction pulse is defined as the timing asymmetry. It This timing asymmetry is used to synchronize the reproduced signal.

The magnetic pattern is recorded such that the timing asymmetry is originally 0.5, but the value changes due to various factors. Timing asymmetry is optimal when its value is in the range of 0.4 to 0.6. If the range is 0.35 to 0.65, synchronization can be achieved by devising the reproduction signal processing system. However, if the range is 0.3 or less or 0.7 or more, synchronization is generally achieved. Can not.

As shown in FIG. 9, the timing asymmetry of Examples 1 and 2 is within the optimum range. The timing asymmetry of Comparative Example 1 is in a range in which synchronization cannot be achieved without devising the reproduction signal processing system, and the timing asymmetry of Comparative Example 2 is no longer in a range in which synchronization can be achieved.

[0117]

As described above, according to the present invention, a photomask having a mask pattern formed with high accuracy is provided. With this photomask, it is possible to manufacture a magnetic disk on which a magnetic pattern is formed with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus used in a photomask manufacturing method according to an embodiment.

FIG. 2 is an explanatory diagram of an irradiation spot overlapping state of the photomask manufacturing method according to the embodiment.

FIG. 3 is an explanatory diagram of an irradiation spot overlapping state of a photomask manufacturing method according to another embodiment.

FIG. 4 is an explanatory diagram of a group of laser beams.

FIG. 5 is an explanatory diagram of a magnetization pattern forming method using a photomask.

FIG. 6 is a schematic diagram showing magnetic flux in the method of FIG.

FIG. 7 is a sectional view of the magnetic recording medium in the thickness direction.

FIG. 8 is an explanatory diagram of a magnetization pattern.

FIG. 9 is a graph showing a measurement result of timing asymmetry.

[Explanation of symbols]

1 Transparent substrate body 10 turntable 20 light sources 25 expander 27 Objective lens 30 slider 41 magnetic disk 42 magnet 44 Photomask

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/027 G11B 5/02 S // G11B 5/02 H01L 21/30 502P F term (reference) 2H095 BA07 BB07 BB14 2H097 AA03 AB07 LA20 5D006 DA03 5D091 AA10 BB08 CC17 CC26 FF20 GG33 5D112 GA19

Claims (8)

[Claims] 1. A method of manufacturing a photomask in which a light shielding layer is formed in a predetermined pattern on a transparent substrate by etching, wherein a photoresist layer is formed on a transparent substrate body having a light shielding layer before etching treatment. A step of forming a latent image pattern according to the above pattern by irradiating the photoresist layer with an energy beam from an energy beam irradiator, and then developing the latent image pattern to form a resist pattern on the light shielding layer; In a method for producing a photomask, which comprises a step of etching a layer and a step of removing a resist pattern, a transparent substrate body on which a photoresist layer is formed is rotated around its center, and an energy beam irradiator is turned on. The substrate is moved relative to the radial direction of rotation, and the energy beam is intermittently irradiated. Method for manufacturing a photomask, and forming the latent image pattern by contiguous with bets. 2. The energy beam irradiator according to claim 1, wherein the energy beam irradiator is stopped at a predetermined position in the radial direction of rotation, and the energy beam is intermittently radiated while the transparent substrate body makes one revolution. The energy beam irradiator is moved by a predetermined pitch in the radial direction of rotation and stopped, and in this state, energy beams are intermittently irradiated while the transparent substrate body makes one revolution, and by repeating this step, the latent image pattern is formed. A method of manufacturing a photomask, comprising: forming a photomask. 3. The photomask according to claim 1, wherein the latent image pattern is formed by intermittently irradiating the energy beam irradiator with etching while continuously moving in the radial direction of rotation. Production method. 4. The method according to any one of claims 1 to 3, wherein only one energy beam is irradiated toward the transparent substrate body, and the beam diameter of the energy beam on the irradiation surface is measured. Is d, and p is the distance that the energy beam irradiator moves in the radial direction for each rotation of the transparent substrate body, p / d is 0.5 to 0.9. Production method. 5. The transparent substrate body according to claim 1, wherein a plurality of energy rays are adjacent to each other in the radial direction of rotation and adjacent energy rays partially overlap with each other. A method of manufacturing a photomask, which comprises irradiating the photomask in a direct direction. 6. The beam diameter according to claim 5, wherein the beam diameters of the adjacent one and the other energy rays on the irradiation surface are d ₁ ,
and d _2, if the distance between the centers of both the energy beam is L, the manufacturing method of a photomask, characterized by the _{2L / (d 1 + d 2} ) of 0.5 to 0.9. 7. A magnetic disk having a magnetic layer is irradiated with energy rays through a photomask, thereby locally heating the magnetic layer and applying an external magnetic field to form a magnetization pattern. A photomask used for that purpose, which is manufactured by the method according to claim 1. 8. A magnetic disk having a magnetic layer is irradiated with energy rays through a photomask, thereby locally heating the magnetic layer and applying an external magnetic field to form a magnetization pattern. A method for forming a magnetization pattern in a magnetic disk, wherein the photomask is manufactured by the method according to any one of claims 1 to 6.