JP2004055048A - Mask for specifying shape of magnetic pattern of magnetic recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mask for specifying a shape of a magnetic pattern by which various information regarding to the mask for specifying the shape of magnetic pattern can be easily specified by the mask alone, and to provide its manufacturing method. <P>SOLUTION: When a magnetic pattern is formed in a magnetic layer by irradiating and heating the magnetic layer of the magnetic recording medium with an energy ray, and impressing an external magnetic field, in a mask 1 which specifies the shape of the magnetic pattern, a mask pattern area which gives a graded effect locally in terms of irradiation intensity of the energy ray to the magnetic layers according to the shapes of the magnetic patterns to be formed, and at the same time, a mark 6 which identifies information concerning the mask 1 is formed with the mask 1 integrally. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mask for defining a magnetization pattern shape of a magnetic recording medium such as a magnetic disk used in a magnetic recording device and a method of manufacturing the same.
[0002]
[Prior art]
A magnetic recording device represented by a magnetic disk device (hard disk drive) is widely used as an external storage device of an information processing device such as a computer, and is also recently used as a moving image recording device or a recording device for a set-top box. Is being done.
[0003]
A magnetic disk device usually includes a shaft for fixing one or more magnetic disks in a skewered manner, a motor for rotating a magnetic disk joined to the shaft via a bearing, and a magnetic disk used for recording and / or reproduction. It comprises a head, an arm to which the head is attached, and an actuator that can move the head to an arbitrary position on the magnetic recording medium via the head arm.
[0004]
The recording / reproducing head is usually a floating head, and moves on a magnetic recording medium at a constant flying height. In addition to the flying head, the use of a contact head (contact head) has been proposed to further reduce the distance from the medium.
[0005]
A magnetic recording medium mounted on a magnetic disk device generally has a NiP layer formed on the surface of a substrate made of an aluminum alloy or the like, performs a required smoothing process, texturing process, and the like, and then forms a metal base layer thereon. , A magnetic layer (information recording layer), a protective layer, a lubricating layer, and the like are sequentially formed. Alternatively, it is manufactured by sequentially forming a metal base layer, a magnetic layer (information recording layer), a protective layer, a lubricating layer, and the like on a surface of a substrate made of glass or the like. Magnetic recording media include in-plane magnetic recording media and perpendicular magnetic recording media. In the longitudinal magnetic recording medium, longitudinal recording is usually performed.
[0006]
The speed of increasing the density of magnetic recording media is increasing year by year, and there are various techniques for achieving this. For example, improvements such as reducing the flying height of the magnetic head, adopting a GMR head as the magnetic head, increasing the magnetic material used for the recording layer of the magnetic disk to have a high coercive force, and improving the information recording track of the magnetic disk Attempts have been made to reduce the distance between the two. For example, 100Gbit / inch ² Is required to have a track density of 100 ktpi or more.
[0007]
Each track is formed with a control magnetization pattern for controlling the magnetic head. For example, it is a signal used for position control of the magnetic head or a signal used for synchronization control. If the number of tracks is increased by narrowing the interval between information recording tracks, a signal used for controlling the position of the data recording / reproducing head (hereinafter, sometimes referred to as a “servo signal”) is also adjusted in the radial direction of the disk. On the other hand, it must be provided densely, that is, more, so that precise control can be performed.
[0008]
It is also desirable to increase the data recording capacity by reducing the area other than the area used for data recording, that is, the area (servo area) used for servo signals and the gap between the servo area and the data recording area to increase the data recording area. There is also a great demand. For this purpose, it is necessary to increase the output of the servo signal and the accuracy of the synchronization signal.
[0009]
Conventionally, a widely used method for forming a servo signal is to make a hole near a head actuator of a drive (magnetic recording device), insert a pin with an encoder into the hole, engage the actuator with the pin, and Is driven to an accurate position to record a servo signal. However, since the center of gravity of the positioning mechanism is different from the center of gravity of the actuator, highly accurate track position control cannot be performed, and it has been difficult to accurately record servo signals.
[0010]
On the other hand, there has also been proposed a technique of forming an uneven servo signal by irradiating a magnetic disk with a laser beam to locally deform the disk surface to form physical unevenness. However, the flying head becomes unstable due to the unevenness and adversely affects recording / reproducing. It is necessary to use a laser beam having a large power to form the unevenness, which increases the cost. It takes time to form the unevenness one by one. There was a problem.
[0011]
For this reason, a new servo signal forming method has been proposed.
One example is a method in which a servo pattern is formed on a master disk having a magnetic layer with a high coercive force, the master disk is brought into close contact with a magnetic recording medium, and a magnetization pattern is transferred by applying an auxiliary magnetic field from outside (US Pat. No. 5,991). , No. 104).
[0012]
Another example is a method of preliminarily magnetizing a medium in one direction, patterning a soft magnetic layer or the like having a high magnetic permeability and a low coercive force on a master disk, and bringing the master disk into close contact with the medium and applying an external magnetic field. It is. The soft magnetic layer functions as a shield, and a magnetization pattern is transferred to an unshielded region (Japanese Patent Application Laid-Open No. 50-60212 (US Pat. No. 3,869,711)) and Japanese Patent Application Laid-Open No. 10-45544 (EP915456). ), Digest of InterMag 2000, GP-06).
[0013]
These techniques use a master disk and form a magnetization pattern on a medium by a strong magnetic field.
In general, the strength of the magnetic field depends on the distance, and when recording a magnetized pattern with the magnetic field, the pattern boundary is likely to be unclear due to the leakage magnetic field. Therefore, in order to minimize the leakage magnetic field, it is essential to bring the master disk and the medium into close contact. Further, as the pattern becomes finer, it is necessary to make the pattern adhere completely without any gap. Usually, both are pressed by vacuum suction or the like.
[0014]
Further, as the coercive force of the medium increases, the magnetic field used for transfer increases, and the leakage magnetic field also increases.
Therefore, each of the above techniques is easy to apply to a magnetic disk having a low coercive force and a flexible floppy (registered trademark) disk which is easily pressed, but the coercive force for high-density recording using a hard substrate is 3000 Oe. It is very difficult to apply such a method to a magnetic disk.
[0015]
In other words, a magnetic disk having a hard substrate may cause minute dust or the like to be interposed when the medium is brought into close contact, causing a defect in the medium or damaging an expensive master disk. In particular, in the case of a glass substrate, there has been a problem that the adhesion is insufficient due to the interposition of dust, so that magnetic transfer cannot be performed, and a crack occurs in the magnetic recording medium.
[0016]
Further, in the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 50-60212 (US Pat. No. 3,869,711), when a pattern having an oblique angle with respect to the track direction of a disk is formed, recording is performed. However, there is a problem that only a pattern having a weak signal intensity can be formed. For a high-coercivity magnetic recording medium having a coercive force of 2000 to 2500 Oe or more, a ferromagnetic material (shielding material) for a pattern of a master disk is made of a saturated magnetic flux such as permalloy or sendust in order to secure a magnetic field strength for transfer. The use of a soft magnetic material with high density is inevitable.
[0017]
However, in the oblique pattern, the magnetic field of the magnetization reversal is in a direction perpendicular to the gap formed by the ferromagnetic layer of the master disk, and the magnetization cannot be tilted in a desired direction. As a result, a part of the magnetic field escapes to the ferromagnetic layer, so that it is difficult to apply a sufficient magnetic field to a desired portion during magnetic transfer, and it is difficult to form a sufficient magnetization reversal pattern and to obtain a high signal strength. With such an oblique magnetization pattern, the reproduction output is greatly reduced more than the azimuth loss with respect to the pattern perpendicular to the track.
[0018]
On the other hand, the techniques described in Japanese Patent Application Nos. 2000-134608 and 2000-134611 form a magnetization pattern on a magnetic recording medium by combining local heating and application of an external magnetic field. For example, the medium is magnetized in one direction in advance, and the medium is locally heated by irradiating energy rays or the like through a patterned mask, and an external magnetic field is applied while lowering the coercive force of the heated area, and applied to the heated area. Recording by an external magnetic field is performed to form a magnetization pattern.
[0019]
According to the present technology, since the external magnetic field is applied by lowering the coercive force by heating, the external magnetic field does not need to be higher than the coercive force of the medium, and recording can be performed with a weak magnetic field. Then, the area to be recorded is limited to the heated area, and no recording is performed even when a magnetic field is applied to the area other than the heated area. Therefore, 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 defect of the medium is not increased.
[0020]
Further, according to the present technology, an oblique magnetization pattern can be formed well. This is because there is no need to shield the external magnetic field with the soft magnetic material of the master disk as in the related art.
[0021]
[Problems to be solved by the invention]
As described above, the magnetization pattern forming technique described in the specification of Japanese Patent Application No. 2000-134611 can form various fine magnetization patterns efficiently and accurately, and can also remove defects of the medium without damaging the medium or the mask. It is an excellent technology that does not increase.
[0022]
However, the mask used in the present technology has a problem that various kinds of information such as the front and back surfaces, the position on the circumference, the direction of forming the mask pattern in the plane, the type, and the like cannot always be properly specified by the mask alone. .
[0023]
More specifically, as a mask used in the present technology, for example, a mask in which a thin film of silicon or the like having a thickness of only 100 nm is provided on a surface of a transparent substrate made of quartz glass or the like having a thickness of 2.3 mm is used. I have. However, since silicon is translucent under visible light and the thickness of the thin film is thin, it is difficult to distinguish between the front and back of the mask. In addition, even if the front and back of the mask can be distinguished under normal visible light, photoresist may be used to manufacture the mask at the actual manufacturing site, in which case work must be performed under yellow light. This makes it more difficult to distinguish between front and back.
[0024]
FIG. 6 is a plan view of a mask used in the conventional magnetic pattern forming method. As shown in FIG. 6, the mask 1 has a large number of straight lines corresponding to the magnetic pattern formed by the magnetic pattern forming method. A mask pattern 2 is formed, and a plurality of spokes 3 as a set of the mask patterns 2 are formed in a curved shape in the radial direction of the mask 1. In particular, among these spokes 3, only one other mask pattern 2 is used to determine the start position (position in the circumferential direction in the mask plane) of the magnetic head for reading a signal when the magnetic recording medium is used. There is a spoke 3 formed of an inspection mask pattern (hereinafter, referred to as an index pattern or an index pattern) formed in a shape different from the above. However, since the width of each mask pattern 2 is very small, about 1 μm, it is almost impossible to visually distinguish the index pattern from other mask patterns 2. Also, the spokes 3 which are the accumulation of the mask patterns 2 are formed to have a narrow width such as about 0.4 mm on the outer circumference and about 0.2 mm on the inner circumference, and are formed in the same shape at equal intervals. In many cases, it is difficult to visually identify the spokes 3 composed of the index pattern from the other spokes 3 and specify the position in the circumferential direction on the mask surface.
[0025]
When inspecting the mask 1, the mask pattern 2 is observed with an atomic force microscope (hereinafter, referred to as AFM) to confirm whether there is any problem in the surface shape of the mask 1. In the AFM, a probe called a cantilever is brought close to an object to be measured, and a surface shape is measured from an amount of movement of the cantilever due to an atomic force. At this time, in order to accurately measure the surface shape of the mask 1, the angle at which the unevenness of the mask pattern 2 extends on the surface of the mask 1, that is, the scanning direction by the cantilever of the AFM must be set with respect to the mask pattern 2. It is necessary to adjust the direction in the plane of the mask 1 so as to be vertical. However, since the width of the mask pattern 2 is very small as described above, it is extremely difficult to visually identify the direction of the mask 1 on which the mask pattern 2 is formed. Therefore, there is a problem that it takes much time and effort to specify the direction perpendicular to the mask pattern 2 and to properly perform the inspection of the mask 1.
[0026]
In order to make it easy to specify such information on the mask, it is conceivable to engrave a mark on the mask 1 or to add some mark with a seal, a magic pen, or the like. However, when the mark is cut or attached by such a method, dust may be generated in the process, and large irregularities are generated on the surface of the mask 1. There is a possibility that the adhesiveness of the resin may be lost or a problem may occur in cleaning. Further, in the case where a mark is formed by a magic or a seal, the mask is irradiated with energy rays at the time of forming the magnetization pattern, so that there is a problem in the durability of the mark.
[0027]
The present invention has been made in view of the above problems, and is a mask for defining the shape of a magnetic pattern when a magnetic pattern is formed on a magnetic layer of a magnetic recording medium, the magnetic recording medium being used when forming the magnetic pattern. A mask for defining a magnetized pattern shape, which can easily specify various types of information on the mask by itself without impairing the adhesion between the mask and the troubles caused by cleaning or irradiation with energy rays. , And a method for producing the same.
[0028]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-described problems, and as a result, the above-mentioned object is effectively achieved by forming marks for specifying various types of information on the mask integrally with the mask. This led to the present invention.
[0029]
The gist of the present invention is that a magnetic layer of a magnetic recording medium is irradiated with energy rays and heated, and when an external magnetic field is applied to form a magnetic pattern on the magnetic layer, a mask that defines the shape of the magnetic pattern is used. According to the shape of the magnetization pattern to be formed, according to the shape of the magnetic pattern, the magnetic layer has a mask pattern region that causes local intensity of irradiation of the energy beam, and a mark for specifying information on the mask, The present invention resides in a mask for defining a magnetic pattern shape which is formed integrally with the mask (claim 1).
[0030]
At this time, the mark specifies at least one of information on the front and back of the mask, a position on a circumference of the mask, a forming direction of a mask pattern in a plane of the mask, and a type of the mask. (Claim 2).
[0031]
Further, the mark may be formed outside the mask pattern region.
[0032]
Preferably, the mask for defining a magnetization pattern shape of the present invention is configured to include a disk-shaped substrate that transmits energy rays, and a shielding layer that is provided on the substrate and that does not transmit energy rays. The mask pattern region is formed by opening at least a part of the shielding layer so as to transmit energy rays in a shape corresponding to the magnetization pattern (claim 4).
[0033]
In this case, the mark may be formed by deforming a part of the substrate and / or the shielding layer.
[0034]
In addition, on the shielding layer, spokes, which are a set of the mask patterns, are formed in a curved shape in the radial direction, and the mark is formed such that at least one of the plurality of spokes has a diameter of the mask larger than other spokes. It may be formed to extend inward and / or outward in the direction (Claim 6). Furthermore, the inner and / or outer ends of the plurality of spokes are parallel to the mask pattern. It may be formed as an angle notch (claim 7).
[0035]
Another aspect of the present invention is a method of manufacturing the mask for defining a magnetic pattern shape, wherein the shielding layer and the mark are formed on the substrate in the same step. And a method of manufacturing the mask for defining a magnetization pattern shape, wherein the shielding layer is provided on the substrate on which the mark is formed in advance (Claim 9).
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings. In the drawings, substantially the same parts are denoted by the same reference numerals and described.
[0037]
The mask according to the present invention defines a shape of a magnetic pattern when a magnetic layer of a magnetic recording medium is irradiated with energy rays and heated, and an external magnetic field is applied to form a magnetic pattern on the magnetic layer. . In addition to a mask pattern region that locally varies the intensity of irradiation of the energy beam with respect to the magnetic layer according to the shape of the magnetic pattern to be formed, a mark for specifying information about the mask is integrated with the mask. It is characterized by the fact that it is formed in a specific way.
[0038]
The information specified by the mark is not particularly limited, and various types of information on the mask can be targeted. Specific examples are (1) front and back of the mask, and (2) type of the mask (the type of the mask). (3) the position on the circumference of the mask (particularly the position of the index pattern), (4) the direction in which the mask pattern is formed in the plane of the mask (particularly in each spoke required for AFM measurement). Direction in which the mask pattern is formed). In the following description, a case of forming a mark for specifying the information (1) to (4) will be described with reference to embodiments. Note that the information specified by one mark is not limited to one type, and a configuration may be such that a plurality of pieces of information can be specified from one mark. Also in the following embodiments, it may be possible to specify a plurality of pieces of information from each mark.
[0039]
The mask to which the present invention is applied is not particularly limited as long as the mask has a mask pattern that causes shading of energy rays according to the magnetization pattern to be formed. Any type of mask can be used, such as a mask having a mask pattern composed of, a mask having a mask pattern for diffusing energy rays, and a hologram mask. In each of the following embodiments, a mask having a mask pattern including a transmission part and a non-transmission part of an energy ray will be described as an example.
[0040]
(1) First embodiment
First, as a first embodiment of the present invention, a description will be given of a magnetic pattern formation defining mask having a mark for mainly specifying the front and back of the mask with reference to FIG. FIG. 1A is a front view of a mask for forming a magnetic pattern, and FIG. 1B is an enlarged cross-sectional view of the mask for defining a magnetic pattern shape in FIG.
[0041]
As shown in FIG. 1A, in a mask 1 for forming a magnetic pattern according to the present embodiment, an inorganic layer 5 having a function as a shielding layer for shielding energy rays is provided on one surface of a substrate 4 that transmits energy rays. Is formed. In the region (mask pattern region) of the inorganic layer 5 that defines the shape of the magnetic pattern, the inorganic layer 5 is opened in accordance with the shape of the magnetic pattern to be formed, and the mask pattern 2 is formed. Further, the mask pattern 2 is arranged such that the spokes 3 as a set of the mask patterns 2 are formed in a radially curved shape on the mask surface for defining the magnetization pattern shape.
[0042]
Further, in the magnetic pattern forming mask 1 of the present embodiment, as shown in FIG. 1B, a notch 6 as a mark is formed at a part of the edge of the surface of the substrate 4 on which the inorganic layer 5 is formed. Is formed. The shape and the number of the notches are not particularly limited, and the notches can be arbitrarily formed.
[0043]
Since the magnetic pattern shape defining mask according to the first embodiment of the present invention is formed as described above, the front and back of the mask can be specified by the presence or absence of the notch 6. Further, by devising the shape, number, and arrangement of the notches, it is possible to specify the type of the mask 1 and the position on the circumference of the mask 1 for defining the magnetic pattern shape.
[0044]
Subsequently, a method of manufacturing the mask for defining a magnetic pattern shape according to the present embodiment will be described.
A notch 6 is provided in a part of an edge of a disk-shaped substrate 4 made of a transparent base material that transmits energy rays, for example, quartz glass, optical glass, soda lime glass, or the like. The notch 6 is formed by positioning so as not to cover at least a portion where the mask pattern 2 is to be formed. When the notch 6 is made different depending on the type of the magnetized pattern shape defining mask 1 to be manufactured, the size, shape and the like are determined in advance for type identification, and the notch 6 is determined according to the size and shape. 6 is formed. Further, the method of forming the notch 6 may be any method such as a physical method such as grinding to prevent dusting after grinding, or a chemical method such as dissolving with hydrofluoric acid. Considering the time of forming the magnetic pattern, a method that does not generate dust is preferable.
[0045]
An inorganic substance such as chromium or silicon is formed by sputtering on the surface of the substrate 4 thus formed, and a photoresist is applied thereon by spin coating or the like, and etching such as reactive ion etching (hereinafter referred to as RIE) is performed. Thus, a desired inorganic material layer 5 is formed. In this case, the portion having the inorganic layer on the transparent substrate is a non-transmitting portion through which energy rays cannot pass, and the portion of only the substrate becomes a transmitting portion through which energy rays pass. It is also preferable to apply an anti-reflection coating made of a dielectric layer to the mask 1. Thereby, the energy rays can be more effectively used.
At this time, the inorganic layer 5 is prevented from being formed in a portion of the mask pattern 2 that defines a region on the mask 1 through which the energy rays pass when forming the magnetization pattern.
[0046]
As described above, the mask for defining a magnetization pattern shape according to the first embodiment is manufactured. Therefore, in order to form the inorganic layer 5 on the surface of the substrate 4 in which the notch 6 is provided in advance, unlike the case where a mark is formed on the substrate after the inorganic layer 5 is formed, dust is generated at the time of formation and the magnetization pattern shape is formed. There is no risk of adhering to the surface of the defining mask. In addition, there is no problem that the durability of the mark is lacking as in the case where the mark is formed with a seal or a magic pen.
[0047]
(2) Second embodiment
Next, as a second embodiment of the present invention, a magnetic pattern forming mask having a mark for mainly specifying the type of the mask (such as the attribute and the serial number of the mask) is shown in a front view of the magnetic pattern forming mask. This will be described with reference to FIG.
As shown in FIG. 2, in the mask for forming a magnetic pattern according to the present embodiment, an inorganic layer 5 having a function as a shielding layer for shielding energy rays is formed on one surface of a substrate 4 that transmits energy rays. . In a region (mask pattern region) for defining the magnetization pattern shape on the surface on which the inorganic layer 5 is formed, the inorganic layer 5 is opened in accordance with the magnetization pattern to be formed, and the mask pattern 2 is formed. The mask patterns 2 are arranged such that the spokes 3, which are a group of the mask patterns 2, are formed in a radially curved shape on the surface of the magnetization pattern shape defining mask 1.
Further, in the present embodiment, in a region outside the mask pattern 2 at the outer edge in the radial direction, the inorganic layer 5 is opened to form a shape capable of functioning as a mark, for example, a symbol such as a character (“sample” in FIG. 2). 8 are formed.
[0048]
Since the magnetized pattern shape defining mask 1 according to the second embodiment is formed as described above, the position on the circumference of the magnetized pattern shape defining mask 1 can be easily specified visually. Further, information on the type of the mask 1 such as the information on the type of the mask 1 and the management number of the mask 1 can be specified.
[0049]
If the symbol 8 is formed in a shape that is different from the shape of the magnetized pattern shape defining mask 1 as viewed from the front and the shape as viewed from the back, the front and back of the magnetized pattern shape defining mask 1 can be specified.
The symbol 8 may be formed in the form of a one-dimensional code such as a bar code as shown in FIG. 7A instead of a character, or may be a PDF417 as shown in FIG. 7B or a QR code as shown in FIG. 7D or a two-dimensional code such as a data code as shown in FIG. 7D, or may be formed as a hologram. Can be read from.
[0050]
Subsequently, a method of manufacturing the mask for defining a magnetization pattern shape will be described.
For example, a transparent substrate such as quartz glass, optical glass, soda lime glass, or the like that is permeable to energy rays is formed in a disk shape to manufacture the substrate 4. On the surface of the substrate 4 thus formed, an inorganic substance such as chromium or silicon is formed by sputtering, a photoresist is applied thereon by spin coating or the like, and desired transmission portions and non-transmission portions are formed by etching such as RIE. I do. In this case, the portion having the inorganic material layer 5 on the transparent substrate is a non-transmission portion of the energy beam, and the portion of only the substrate 4 is a transmission portion of the energy beam. However, in the present embodiment, in addition to the region where the mask pattern 2 used for forming the magnetic pattern is located, the region of the outer edge of the mask 1 that does not cover the mask pattern 2 is one or more of characters, patterns, and arrangements having specific information. A plurality of transparent portions are formed, which is designated by symbol 8.
At this time, if the inorganic layer 5 is not formed in a region where the symbol 8 is to be formed in advance, and the symbol 8 is formed as a mark simultaneously with the formation of the mask pattern 2, the mark can be formed without increasing the number of manufacturing steps. Can be preferably formed.
[0051]
As described above, the magnetic pattern shape defining mask according to the second embodiment is manufactured. Therefore, unlike the case where a mark is formed by engraving on the substrate, no dust is generated in the mark forming step, and large irregularities are generated on the surface of the mask 1, and the adhesion between the mask 1 and the magnetic recording medium is lost during the formation of the magnetization pattern. There is no risk that the mark will disappear or that the mark will disappear due to cleaning. Further, even when the mask 1 is irradiated with energy rays during the formation of the magnetization pattern, the mark does not disappear.
[0052]
(3) Third embodiment
Next, as a third embodiment of the present invention, a magnetic pattern forming mask having a mark for mainly specifying a position on the circumference of the mask will be described with reference to FIG. 3 which is a front view of the magnetic pattern forming mask. explain.
As shown in FIG. 3, in the mask for forming a magnetic pattern according to the present embodiment, an inorganic layer 5 having a function as a shielding layer for shielding energy rays is formed on one surface of a substrate 4 that transmits energy rays. . In a region (mask pattern region) for defining the magnetization pattern shape on the surface on which the inorganic layer 5 is formed, the inorganic layer 5 is opened in accordance with the magnetization pattern to be formed, and the mask pattern 2 is formed. The mask patterns 2 are arranged such that the spokes 3, which are a group of the mask patterns 2, are formed in a radially curved shape on the surface of the magnetization pattern shape defining mask 1.
Further, in the present embodiment, one of the plurality of spokes 3 is formed to extend radially outward and inward by about 0.5 mm, and the protruding portion 7 is formed to be a mark. The protruding portion 7 has a transmission portion formed on the outside and inside in the radial direction of the spoke 3 including the index pattern.
[0053]
Usually, the spokes 3 of the mask 1 for defining the magnetization pattern shape are formed to have the same length in the radial direction. The portion where the mask pattern 2 is formed corresponds to a region where a magnetic pattern is formed on the magnetic layer of the magnetic recording medium when the magnetic pattern is formed. The magnetization pattern formed on the magnetic recording medium is read while rotating the magnetic recording medium, and is used for position control and synchronization control of the magnetic head. Therefore, since it is necessary to have a signal on a concentric circle, the length of the spoke is the same in the radial direction. Therefore, if one of these spokes 3 is formed long, it can be easily confirmed visually.
[0054]
Since the magnetized pattern shape defining mask according to the third embodiment is formed as described above, the position on the circumference of the magnetized pattern shape defining mask 1 can be easily specified visually.
Further, the protruding portion 7 may be formed on any of the spokes 3, but it is preferable to form the protruding portion 7 on the spoke 3 including the index pattern as in the present embodiment. Thereby, it is possible to easily specify which spoke 3 includes the index pattern.
[0055]
Further, in the present embodiment, the spokes 3 are formed as the protruding portions 7 by extending the spokes 3 inward and outward in the radial direction. However, the spokes 3 may be formed by extending only inward in the radial direction. Is also good. Further, although not preferable because the storage capacity of the magnetic recording medium is reduced, a mark may be formed by shrinking and forming a specific spoke in some cases.
Further, the number of spokes 3 as marks is not limited to one, and several spokes 3 may be provided as necessary.
Further, the distance for extending the spoke is not limited to about 0.5 mm, but may be extended by a distance according to the purpose. However, if the spokes are formed so as to extend about 0.5 mm or more as in the present embodiment, the protruding portion 7 can be visually identified, that is, the mark can be identified with the naked eye, and the information can be easily specified.
[0056]
Subsequently, a method of manufacturing the mask for defining a magnetization pattern shape will be described. As in the second embodiment, for example, a transparent base material that is transparent to energy rays, such as quartz glass, optical glass, and soda lime glass, is formed in a disk shape, and the substrate 4 is manufactured. On the surface of the substrate 4 thus formed, an inorganic substance such as chromium or silicon is formed by sputtering, a photoresist is applied thereon by spin coating or the like, and a desired transmitting portion and a non-transmitting portion are formed by etching such as RIE. create. In this case, the portion having the inorganic layer 5 on the transparent substrate is the non-transmitting portion 5 for energy rays, and the portion of only the substrate 4 is the transmitting portion for energy rays. However, in the present embodiment, in addition to the region where the mask pattern 2 used for forming the magnetization pattern is located, the transmitting portion is also formed in the radially outer region and the radially inner region of the spoke 3 including the index pattern, and the protruding portion 7 is formed. I do.
[0057]
At this time, if the inorganic layer 5 is not formed in a region where the protruding portion 7 is formed in advance, and the protruding portion 7 as a mark is formed at the same time as the formation of the mask pattern 2, the number of manufacturing steps is increased. Marks can be formed, which is preferable.
[0058]
As described above, the mask for defining the magnetization pattern shape according to the third embodiment is manufactured. Therefore, unlike the second embodiment, unlike the case where a mark is formed by cutting the substrate, no dust is generated when forming the mark, and large irregularities are generated on the mask surface. There is no loss of adhesion between them. Further, there is no problem that the mark disappears due to the cleaning. Furthermore, even if the mask is irradiated with energy rays during the formation of the magnetization pattern, the mark does not disappear.
[0059]
(4) Fourth embodiment
Next, as a fourth embodiment of the present invention, FIG. 4 is a front view of the magnetic pattern forming mask, mainly for a magnetic pattern forming mask having a mark for specifying the mask pattern forming direction in the plane of the mask. This will be described with reference to FIG.
As shown in FIG. 4, in the magnetic pattern forming mask according to the present embodiment, an inorganic layer 5 having a function as a shielding layer for shielding energy rays is formed on one surface of a substrate 4 that transmits energy rays. . In a region (mask pattern region) for defining the magnetization pattern shape on the surface on which the inorganic layer 5 is formed, the inorganic layer 5 is opened in accordance with the magnetization pattern to be formed, and the mask pattern 2 is formed. The mask patterns 2 are arranged such that the spokes 3, which are a group of the mask patterns 2, are formed in a radially curved shape on the surface of the magnetization pattern shape defining mask 1.
Further, in the present embodiment, a notch 9 having an angle parallel to the mask pattern 2 constituting the spoke 3 is formed as a mark at a radially outer end of the spoke 3. Each of the mask patterns 2 is formed at a certain angle on the surface of the magnetization pattern shape defining mask 1, and the mask patterns 2 having the same angle are radially aggregated to form spokes 3. Further, one spoke 3 is not necessarily a set of mask patterns 2 having one angle, and for example, in this embodiment, four types of mask patterns formed at different angles as shown in an enlarged manner in FIG. 2 assemble to form spokes 3.
[0060]
Since the magnetization pattern shape defining mask 1 according to the fourth embodiment is formed as described above, the angle of the mask pattern 2 on the magnetization pattern shape defining mask 1 can be easily specified. The effect of this will be described. After manufacturing the mask 1 for defining the magnetic pattern shape, it is necessary to inspect whether the mask pattern 2 is formed correctly. The inspection is performed by measuring the width of the mask pattern 2 using an AFM or the like. However, in order to accurately measure the width of the mask pattern 2, it is necessary to adjust the measurement direction to a direction perpendicular to the mask pattern 2. For example, when the inspection is performed by the AFM, it is necessary to make the operation direction of the cantilever of the AFM perpendicular to the mask pattern 2 on the surface of the mask 1. Conventionally, since the mask pattern 2 is very fine, it cannot be visually observed, and it has been difficult to determine a direction perpendicular to the mask pattern 2. However, by forming the notch 9 at an angle parallel to the mask pattern 2 as in the present embodiment, the direction perpendicular to the mask pattern 2 can be easily specified, and inspection can be performed easily and precisely. Can be performed.
[0061]
Note that it is also possible to configure so that the type of the mask 1 can be specified by the difference in the shape of the notch 9. Further, when the notch 9 is different for each spoke 3, it is also possible to configure so that the position on the circumference of the magnetization pattern shape defining mask 1 can be specified.
[0062]
Subsequently, a method of manufacturing the mask 1 for defining a magnetization pattern shape will be described. As in the second and third embodiments, for example, a transparent base material that is transparent to energy rays, such as quartz glass, optical glass, and soda lime glass, is formed in a disc shape, and the substrate 4 is manufactured. I do. On the surface of the substrate 4 thus formed, an inorganic substance such as chromium or silicon is formed by sputtering, a photoresist is applied thereon by spin coating or the like, and desired transmission portions and non-transmission portions are formed by etching or the like. In this case, the portion having the inorganic material layer 5 on the transparent substrate is a non-transmission portion of the energy beam, and the portion of only the substrate 4 is a transmission portion of the energy beam. However, in the present embodiment, in addition to the region where the mask pattern 2 used for forming the magnetization pattern is located, and a region near the outer edge of the mask 1 that does not cover the mask pattern 2, a transmission part having a notch 9 shape parallel to the mask pattern 2 is formed. Form. That is, a pattern having the same angle as the mask pattern 2 on the radially inner side is formed on the radially outer side of the area defining the magnetization pattern shape, and the notches 9 are formed by gathering the patterns in parallel. At this time, if the inorganic layer 5 is not formed in a region where the notch 9 is to be formed in advance, and the notch 9 is formed simultaneously with the pattern formation, the mark can be formed without increasing the number of manufacturing steps. Is preferred.
[0063]
As described above, the mask for defining the magnetization pattern shape according to the fourth embodiment is manufactured. Therefore, similarly to the second embodiment and the third embodiment, unlike the case where the substrate is cut and marked, there is no dust generation in the mark forming step, and large irregularities are generated on the surface of the mask 1, so that the magnetic pattern is not formed when the magnetic pattern is formed. There is no fear that the adhesion between the recording medium and the recording medium is lost, and that the mark disappears due to cleaning. Further, even when the mask 1 is irradiated with energy rays during the formation of the magnetization pattern, the mark does not disappear.
[0064]
It should be noted that all or all two or more of the various marks (notches 6, symbols 8, protrusions 7, and notches 9 of the substrate) described in each of the above-described first to fourth embodiments are combined. Thus, they may be formed simultaneously on a single mask. Also, for any type of mark, only one mark may be formed for a single mask, or two or more marks may be formed.
[0065]
By the way, all the above-mentioned masks 1 for defining a magnetic pattern shape of the present invention have an inorganic layer 5 formed on one surface of a substrate 4. When the inorganic layer 5 is formed, photolithography may be used to form a region where a non-transmissive portion such as a mark or a mask pattern 2 is not formed and a region where a non-transmissive portion is formed. In photolithography, as shown in FIG. 5A, first, a photoresist is applied on the surface of the substrate 4 to form a thin film 10 of the photoresist. However, when the cross section of the substrate 4 is rectangular, the photoresist thin film 10 becomes thicker in the peripheral region of the substrate 4 and the cross section of the photoresist thin film 10 has a shape like a ski jump table (hereinafter, ski jump). Shape). In order to prevent this, in any of the first to fourth embodiments, it is desirable to provide a chamfer 27 as shown in FIG. By providing the chamfer 27, even when the photoresist thin film 10 is formed on the substrate 4, the ski jump shape is not formed, and the photoresist thin film 10 can be formed uniformly, so that the mask is formed. Pattern 2 and marks can be formed with high accuracy.
[0066]
Next, a method for forming a magnetization pattern using the mask according to the present invention will be described. First, a technique of forming a magnetization pattern on a magnetic recording medium by combining local heating and application of an external magnetic field according to the present invention will be described.
In the magnetization pattern forming method of the present invention, preferably, after applying a first external magnetic field to previously magnetize the magnetic layer uniformly in a desired direction, locally heating the magnetic layer and simultaneously applying the second external magnetic field. The heating unit is magnetized in a direction opposite to the desired direction to form a magnetized pattern. Thereby, mutually opposite magnetic domains are clearly formed, so that a magnetization pattern with high signal intensity and good C / N and S / N can be obtained.
[0067]
First, a strong first external magnetic field is applied to the magnetic recording medium to uniformly magnetize the entire magnetic layer in a desired magnetization direction. As a means for applying the first external magnetic field, a magnetic head may be used, or an electromagnet or a permanent magnet may be arranged and used so as to generate a magnetic field in a desired magnetization direction. Further, these means may be used in combination.
Note that the desired magnetization direction is the same or opposite to the running direction of the data recording / reproducing head (the relative movement direction of the medium and the head) in the case of a medium whose easy axis of magnetization is in the in-plane direction. When the axis of easy magnetization is perpendicular to the in-plane direction, it is one of the perpendicular directions (upward or downward). Therefore, the first external magnetic field is applied so as to be magnetized in such a manner. When the medium has a disk shape, the direction in which the first external magnetic field is applied is preferably one of a circumferential direction, a radial direction, and a direction perpendicular to the plate surface.
[0068]
To uniformly magnetize the entire magnetic layer in a desired direction means to magnetize the entire magnetic layer in substantially the same direction, but not strictly all, and at least the region where the magnetization pattern is to be formed is in the same direction. It only needs to be magnetized.
The strength of the first external magnetic field may be set in accordance with the coercive force of the magnetic layer, but it is preferable that the magnetic layer be magnetized by a magnetic field at least twice the coercive force (static coercive force) at room temperature. If it is lower than this, the magnetization may be insufficient. However, usually, the coercive force of the magnetic layer at room temperature is about 5 times or less due to the capability of the magnetizing device used for applying the magnetic field. The room temperature is, for example, 25 ° C. The coercive force of the magnetic recording medium is substantially the same as the coercive force of the magnetic layer (recording layer).
[0069]
The magnetic layer generally has a static coercive force (sometimes simply referred to as a coercive force) and a dynamic coercive force. For local heating, it is sufficient that the magnetic layer can be heated at least to a temperature at which the dynamic coercive force of the magnetic layer is reduced to some extent. . Of course, heating may be performed to a temperature at which the static coercive force decreases. Preferably, it is heated to 100 ° C. or higher. A magnetic layer having a heating temperature of less than 100 ° C. and affected by an external magnetic field tends to have low stability of magnetic domains at room temperature.
[0070]
However, the heating temperature is desirably low within a range where a desired decrease in coercive force can be obtained. For example, the temperature is close to the temperature at which the magnetization of the magnetic layer disappears or the Curie temperature. If the heating temperature is too high, thermal diffusion to regions other than the region to be heated tends to occur, and the pattern may be blurred. Also, the magnetic layer may be deformed. Further, usually, a lubricating layer made of a lubricant is formed on the surface of the magnetic recording medium, and the lower the heating temperature is, the more preferable it is to prevent adverse effects such as deterioration of the lubricant due to heating. The heating may cause the lubricant to undergo degradation such as decomposition or may be vaporized and reduced, and particularly in the case of proximity exposure, the vaporized lubricant may adhere to a mask or the like. Therefore, in order to make the magnetic pattern forming method of the present invention industrially applicable to a magnetic recording medium having a lubricating layer, it is desirable that the heating temperature be as low as possible.
[0071]
Therefore, it is preferable that the heating temperature be equal to or lower than the Curie temperature of the magnetic layer. For example, the temperature is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and further preferably 200 ° C. or lower.
Next, the direction of the second external magnetic field applied simultaneously with the heating is generally opposite to the direction of the first external magnetic field. When the medium has a disk shape, the direction in which the second external magnetic field is applied is preferably one of a circumferential direction, a radial direction, and a direction perpendicular to the plate surface.
[0072]
When a pulsed energy beam is used for heating, the second external magnetic field may be applied continuously or in a pulsed manner. When the second external magnetic field is a pulsed magnetic field, it may be only a pulsed magnetic field component or a combination of a pulsed magnetic field component and a static magnetic field component. At this time, the sum of the pulse magnetic field component and the static magnetic field component is defined as the intensity of the second external magnetic field.
[0073]
As the maximum intensity of the second external magnetic field increases, the magnetization pattern is more easily formed. Although the optimum strength varies depending on the characteristics of the magnetic layer of the magnetic recording medium, when the second external magnetic field is a static magnetic field, it is preferably at least ８ of the coercive force (static coercive force) at room temperature. If it is lower than this, the heating unit may be magnetized again in the same direction as the surroundings under the influence of the magnetic field from the surrounding magnetic domains during cooling. However, the coercive force of the magnetic layer at room temperature is preferably ／ or less, more preferably 倍 or less. If it is larger than this, the magnetic domains around the heating unit may be affected.
[0074]
When the second external magnetic field is a pulse-shaped magnetic field, it is preferable that the second external magnetic field is at least ／ of the coercive force (static coercive force) at room temperature. If it is too weak, the heated region may not be magnetized satisfactorily. More preferably, it is 3/4 or more of the static coercive force at room temperature. A magnetic field stronger than the static coercive force at room temperature may be applied. However, the magnetic field is smaller than the dynamic coercive force of the magnetic layer at room temperature. This is because if the second external magnetic field is larger than this, the magnetization of the non-heated region is affected.
[0075]
In the present invention, the magnetic field intensity value H (Oe) can be substituted with the magnetic flux density value B (Gauss) as it is. In general, there is a relation of B = μH (where μ represents magnetic permeability). However, since the formation of a magnetization pattern is usually performed in air, the magnetic permeability is 1 and the relation of B = H holds. is there.
As the means for applying the second external magnetic field, a magnetic head may be used, or a plurality of electromagnets or permanent magnets may be arranged and used so as to generate a magnetic field in a desired magnetization direction. They may be used in combination. In order to efficiently magnetize a high coercivity medium suitable for high-density recording, a permanent magnet such as a ferrite magnet, a neodymium-based rare-earth magnet, or a samarium-cobalt-based rare-earth magnet is suitable.
[0076]
When the second external magnetic field is a pulsed magnetic field, it may be only the pulsed magnetic field applying means or a combination of the pulsed magnetic field applying means and the static magnetic field applying means. For example, in the former, only a pulsed magnetic field is generated by an electromagnet or the like. For example, in the latter case, a static magnetic field of a certain magnitude is given by a permanent magnet or an electromagnet, and a higher magnetic field is applied in a pulse form by the electromagnet. It is preferable to use an air-core coil having a small inductance since the pulse width can be narrowed and the magnetic field application time can be shortened. Also, other electromagnets such as a yoke type may be used instead of the permanent magnet.
[0077]
When the static magnetic field and the pulsed magnetic field are combined, the magnetic field applied in a pulsed manner can be reduced. In general, as the magnetic field of an electromagnet increases, it becomes more difficult to shorten the pulse width, so that the pulse width is easily reduced accordingly.
Alternatively, the pulsed magnetic field can be applied by a method in which a magnet that constantly generates a magnetic field is brought close to the magnetic recording medium only for a short time. For example, the medium may be rotated at a predetermined speed or more while a magnetic field is applied to a part of the magnetic recording medium by a permanent magnet.
[0078]
When the second external magnetic field is a combination of a static magnetic field and a pulsed magnetic field, the static magnetic field strength is made smaller than the static coercive force of the magnetic layer at room temperature. It is preferably at most 2/3 of the static coercive force, more preferably at most 1/2 times. If it is too large, it will affect the formed magnetization pattern and not only will the output drop, but also the modulation will deteriorate. Although there is no particular lower limit, if it is too weak, the significance of using a static magnetic field is reduced. For example, the lower limit is set to 1/8 or more of the static coercive force of the magnetic layer at room temperature.
[0079]
Next, the pulse width when the second external magnetic field is a pulsed magnetic field will be described. In the present invention, the pulse width of the pulse-shaped magnetic field component of the second external magnetic field is simply referred to as the pulse width of the second external magnetic field. Here, the pulse width of the magnetic field indicates a half width.
The pulse width of the second external magnetic field is usually 100 msec or less. Preferably, it is 10 msec or less. The shorter the pulse width of the second external magnetic field, the larger the upper limit of the magnetic field that can be applied. This is because the value of the dynamic coercive force changes according to the application time of the magnetic field, and the shorter the pulse width of the second external magnetic field, the larger the dynamic coercive force of the magnetic layer at room temperature. More preferably, it is 1 msec or less.
[0080]
However, it is preferably at least 10 nsec. If the length is too short, the dynamic coercive force increases accordingly, and the second external magnetic field required to magnetize the heating region increases. Further, although it depends on the magnitude of the magnetic field, the rise and fall of the magnetic field requires time due to the characteristics of the electromagnet, so that there is a limit to shortening the pulse width. More preferably, it is set to 100 nsec or more. Here, the pulse width of the magnetic field indicates a half width.
[0081]
When a pulsed energy beam is used for local heating, the pulse width of the second external magnetic field is equal to or greater than the pulse width of the pulsed energy beam. If it is less than this, the magnetic field changes during local heating, so that the magnetization pattern is not formed well.
It is preferable that the pulsed energy beam and the pulsed second external magnetic field are synchronized and applied simultaneously. Normally, it is considered that the pulse width of the magnetic field is longer than the pulse width of the energy ray. In this case, a pulse of the second external magnetic field is applied, and control is performed so that the pulse of the energy ray is applied where the magnetic field is maximized. Is preferred.
[0082]
When a pulse-shaped magnetic field is applied as the second external magnetic field to a magnetic recording medium or an AFC medium having an increased dynamic coercive force, the effect is particularly high. For example, there is a magnetic recording medium having two magnetic layers each having a magnetic layer for recording and a stabilizing magnetic layer for maintaining thermal stability. Since the stabilizing magnetic layer works to suppress the instantaneous magnetization reversal of the recording magnetic layer, the dynamic coercive force is high, and it is difficult to form a magnetization pattern by the conventional method. When an external magnetic field near or above the static coercive force is applied to such a medium in a pulse form, a good magnetization pattern can be formed.
[0083]
The second external magnetic field can form a plurality of magnetization patterns at once by applying the external magnetic field over the heated large area.
When local heating can be performed on the entire surface of the magnetic recording medium at one time, it is desirable to apply a second external magnetic field to the entire surface of the medium simultaneously with heating to form a magnetization pattern. As a result, a magnetic pattern can be formed in a shorter time, and the cost can be greatly reduced. To apply a magnetic field to only a part of the medium, the magnet arrangement is often devised or specific measures are taken so that the magnetic field does not reach other areas, but it is necessary to apply it to the entire surface. Absent. In addition, since a rotating mechanism or a moving mechanism is not required, the apparatus configuration is simplified, and a magnetic recording medium can be obtained at low cost.
[0084]
FIG. 8 shows an example of a specific transfer mechanism according to the present invention.
A mask 14 is placed on a magnetic disk (magnetic recording medium) 11 via a spacer 17, a light shielding plate 13 is arranged above the mask 14, and an energy beam 15 is irradiated through an opening 13 a. As described above, the mask 14 has a transmission portion and a light shielding portion formed in accordance with the magnetization pattern to be formed.
[0085]
Permanent magnets 12a (N-pole) and 12b (S-pole) are attached to both sides of the opening 13a on the light-shielding plate 13, and air-core coils (electromagnets) 18a and 18b in which coils are wound several dozen times in a loop shape. They are arranged along the permanent magnets 12a and 12b. Permanent magnets 12c (N-pole) and 12d (S-pole) are also mounted on the opposite surface of the magnetic disk 11, and air-core coils (electromagnets) 18a and 18b in which the coils are wound several tens of times in a loop shape. They are arranged along the permanent magnets 12c and 12d.
[0086]
The air-core coils 18a and 18b are connected to each other by a conductor, and both ends are connected to a DC power supply 21, a capacitor 22, and a thyristor 23 as shown in the figure. The air-core coils 18a and 18b are each bent in a U-shape so that the magnetic disk 11 can be easily attached and detached.
Here, by the permanent magnets 12a to 12d, in the direction opposite to the uniform magnetization in the circumferential direction of the magnetic disk, about 1.7 kGauss in the disk inner peripheral area (at a position of a radius of 21 mm) and the disk outer peripheral area (radius of 46.5 mm). ), A magnetic field of about 1.9 kGauss is always applied.
[0087]
In order to apply a pulsed external magnetic field, first, the DC power supply 21 causes the capacitor 22 to have a potential difference of 750V. Next, when a trigger signal is generated from the trigger device 24 in accordance with the timing at which an external magnetic field is to be applied, and the trigger signal is input to the gate terminal of the thyristor 23, a current flows through the air core coils 18a and 18b due to the potential difference accumulated in the capacitor 22. It flows at a stretch. The pulse current causes a pulse width of 200 μsec around the coil, a maximum intensity of about 1.8 kGauss in the disk inner peripheral area (at a radius of 21 mm) and a maximum intensity of about 2 kGauss in the disk outer peripheral area (at a radius of 46.5 mm). A pulse magnetic field of about 0.0 kGauss is generated.
[0088]
As shown in FIG. 8B, the magnetic field generated by the air-core coils 18a and 18b acts to assist the magnetic field generated by the permanent magnets 12a to 12d. A pulse-shaped magnetic field having a maximum intensity of about 3.9 kGauss is applied in the outer peripheral area of the disk (at a radius of 46.5 mm).
On the other hand, the trigger signal from the trigger device 24 is input to an energy ray source 26 such as an excimer laser (wavelength 248 nm) through a delay device (delay) 25, thereby generating a pulsed energy beam. The energy beam passes through a programmable shutter, a beam expander, a prism array, and the like (not shown), and then has a pulse width of several tens nsec and an energy density of 100 to 200 mJ / cm, for example. ² Is irradiated as a pulse-like energy beam 5.
[0089]
Normally, since the rise and fall of the magnetic field requires time due to the characteristics of the electromagnet, the delay device (delay) 25 emits the energy beam so that the energy beam 15 is irradiated just when the magnetic field intensity is maximized. Adjust
As a result, a pulsed magnetic field of about 3000 Oe in total is applied simultaneously with the irradiation of the energy rays 15. Since the dynamic coercive force of the heated area of the magnetic disk 11 has decreased to 3000 Oe or less, only the heated area is reversely magnetized by the pulsed magnetic field, and a magnetization pattern is formed. Note that a pulsed current may be directly supplied from a DC power supply without using a capacitor or the like.
[0090]
For example, when the medium is a disk-shaped magnetic recording medium having a small diameter of 2.5 inches or less, it is preferable because energy rays can be applied to the entire surface of the disk and a magnetic field can be applied by a simple arrangement or means. More preferably, the diameter is 1 inch or less.
When it is desired to apply a magnetic field in the circumferential direction to a disk-shaped magnetic recording medium, a large magnetic field in the circumferential direction can be easily generated by supplying a large vertical pulse current to the center of the medium. This is particularly preferable when applied to a disk-shaped magnetic recording medium having a small diameter of 1 inch or less.
[0091]
The present invention is suitable for forming a magnetization pattern having control information for controlling a recording / reproducing magnetic head. For example, it is a pattern for generating a signal corresponding to the position of the head.
The control information is used to control recording / reproducing means such as a magnetic head using the information.For example, servo information for positioning the magnetic head on a data track and the position of the magnetic head on a medium are determined. Address information, synchronization information for controlling the recording / reproducing speed of the magnetic head, and the like. Alternatively, reference information for writing servo information later is also included.
[0092]
These control magnetization patterns need to be formed with high precision. In particular, since servo patterns are data track position control patterns, poor servo pattern accuracy leads to poor head position control. A data pattern having such a high positional accuracy cannot be theoretically recorded. Therefore, as the recording density of the medium increases, the servo pattern needs to be formed with higher accuracy.
[0093]
In the present invention, a highly accurate servo pattern or reference pattern can be obtained. Therefore, the present invention is particularly effective when applied to a magnetic recording medium for high-density recording having a track density of 40 kTPI or more.
Next, a method for locally heating the magnetic layer according to the present invention will be described.
The heating means only needs to have a function capable of partially heating the surface of the magnetic layer, but in consideration of prevention of heat diffusion to unnecessary parts and controllability, it is easy to control the power control and the size of the part to be heated. Utilize energy rays such as laser.
[0094]
Here, by using a mask together, a plurality of magnetization patterns can be formed at a time by irradiating an energy ray through the mask, so that the magnetization pattern forming step is short and simple.
It is preferable to control the heating portion and the heating temperature by making the energy beam more pulse-shaped than continuous irradiation. In particular, use of a pulse laser light source is preferred. A pulsed laser light source oscillates a laser intermittently in a pulsed manner. Compared to a continuous laser which is intermittently pulsed by an optical component such as an acousto-optic device (AO) or an electro-optic device (EO), it is pulsed. It is very preferable that a laser having a high power peak value can be irradiated in a very short time and heat accumulation hardly occurs.
[0095]
When a continuous laser is pulsed by an optical component, the pulse has substantially the same power over the pulse width. On the other hand, a pulsed laser light source accumulates energy by resonance in the light source, for example, and emits the laser at once as a pulse. In the present invention, in order to form a magnetization pattern having high contrast and high accuracy, it is preferable to rapidly heat the film in a very short time and then rapidly cool it. Therefore, a pulse laser light source is suitable.
[0096]
It is preferable that the medium surface on which the magnetization pattern is formed has a large temperature difference between when the pulsed energy beam is irradiated and when it is not irradiated, in order to increase the pattern contrast or the recording density. Therefore, it is preferable that the temperature be lower than room temperature when the pulsed energy beam is not irradiated. Room temperature is about 25 ° C.
When a pulsed energy beam is used, an external magnetic field may be applied continuously or in a pulsed manner.
[0097]
The wavelength of the energy ray is preferably 1100 nm or less. If the wavelength is shorter than this, the diffraction effect is small and the resolution is increased, so that a fine magnetization pattern is easily formed. More preferably, the wavelength is 600 nm or less. In addition to the high resolution, the diffraction is small, so that the spacing between the mask and the magnetic recording medium by the gap can be widened, handling is easy, and there is an advantage that the magnetization pattern forming apparatus is easy to configure. Further, the wavelength is preferably 150 nm or more. If it is less than 150 nm, the absorption of the synthetic quartz used for the mask becomes large, and the heating tends to be insufficient. If the wavelength is 350 nm or more, the optical glass can be used as a mask.
[0098]
More specifically, an excimer laser (157, 193, 248, 308, 351 nm), a second harmonic (532 nm), a third harmonic (355 nm), or a fourth harmonic (266 nm) of a Q switch laser (1064 nm) of YAG, An Ar laser (488 nm, 514 nm), a ruby laser (694 nm), or the like is used.
The power of the energy beam may be selected to an optimum value according to the magnitude of the external magnetic field, but the power per pulse of the pulsed energy beam is 1000 mJ / cm. ² It is preferable to set the following. If a power larger than this is applied, the surface of the magnetic recording medium may be damaged and deformed by the pulsed energy rays. If the roughness Ra of the medium is increased to 3 nm or more and the undulation Wa is increased to 5 nm or more due to deformation, there is a possibility that the running of the flying / contact type head may be hindered.
[0099]
More preferably, 500 mJ / cm ² Or less, more preferably 200 mJ / cm ² It is as follows. In this region, a magnetization pattern with high resolution is easily formed even when a substrate having relatively large thermal diffusion is used. The power is 10mJ / cm ² It is preferable to make the above. If it is smaller than this, the temperature of the magnetic layer hardly rises and magnetic transfer hardly occurs. Since the effect of the diffraction of the energy beam changes depending on the pattern width, the optimum power also changes according to the pattern width. Also, the shorter the wavelength of the energy ray, the lower the upper limit of the power that can be applied.
[0100]
If the magnetic layer, the protective layer, and the lubricating layer are likely to be damaged by the energy rays, measures should be taken to reduce the power of the pulsed energy rays and increase the intensity of the magnetic field applied simultaneously with the pulsed energy rays. Can also be taken. In irradiating the pulsed energy beam through the protective layer and the lubricating layer, it may be necessary to re-apply after the irradiation in consideration of the damage (decomposition, polymerization) of the lubricant and the like.
[0101]
It is desirable that the pulse width of the pulsed energy beam be 1 μsec or less. If the pulse width is wider than this, the heat generated by the energy applied to the magnetic recording medium is dispersed, and the resolution tends to decrease. When the power per pulse is the same, a shorter pulse width and irradiation with strong energy at a time tend to reduce thermal diffusion and increase the resolution of the magnetization pattern. More preferably, it is 100 nsec or less. In this region, even when a substrate such as Al having a relatively large thermal diffusion of a metal is used, a magnetization pattern with high resolution is easily formed. When forming a pattern having a minimum width of 2 μm or less, the pulse width is preferably set to 25 nsec or less. That is, if importance is placed on the resolution, the shorter the pulse width, the better. Further, the pulse width is preferably 1 nsec or more. This is because it is preferable to keep the heating until the magnetization reversal of the magnetic layer is completed.
[0102]
In the present invention, the minimum width of a pattern refers to the narrowest length in the pattern. In the case of a square pattern, the short side is used. In the case of a circle, the diameter is used.
As one type of pulsed laser, there is a laser such as a mode-locked laser which can generate picosecond and femtosecond level ultrashort pulses at a high frequency. During the period of irradiating the ultrashort pulse at a high frequency, the laser is not irradiated for a very short time between each ultrashort pulse, but the heating portion is hardly cooled because it is a very short time. For example, a region once heated to 200 ° C. is kept at approximately 200 ° C.
[0103]
Therefore, in such a case, the continuous irradiation period (the continuous irradiation period including the time during which the laser is not irradiated between the ultrashort pulses) is defined as one pulse. In addition, the integral value of the irradiation energy amount during the continuous irradiation period is expressed as the power per pulse (mJ / cm ² ).
In addition, an energy beam such as a laser generally has an intensity distribution (energy density distribution) in a beam spot, and a difference in temperature rise due to the energy density also occurs when the energy beam is irradiated and locally heated. For this reason, a difference in transfer intensity locally occurs due to uneven heating. Therefore, preferably, the energy beam is subjected to an intensity distribution uniforming process in advance. The distribution of the heating state in the irradiated area can be suppressed small, and the distribution of the magnetic intensity of the magnetization pattern can be suppressed small. Therefore, when reading the signal intensity using the magnetic head, it is possible to form a magnetization pattern with high signal intensity uniformity.
[0104]
Examples of the processing for equalizing the intensity distribution include the following processing. For example, a homogenizer or a condenser lens is used to make the energy uniform, or a light-shielding plate or a slit is used to transmit only a portion having a small intensity distribution of the energy ray and to expand it as necessary.
The mask of the present invention is a so-called photomask having a transmission part and a light-shielding part for energy rays. The intensity distribution of the energy rays is changed according to the magnetization pattern to be formed, and the density of the energy rays is changed on the magnetic disk surface. Intensity distribution). Thereby, a plurality of or a large area of the magnetized pattern can be formed at a time, so that the magnetized pattern forming step is short and simple.
[0105]
The mask need not cover the entire surface of the magnetic disk. If there is a size including a repeating unit of the magnetization pattern, it can be moved and used.
Further, the material of the mask is not limited. However, in the present invention, it is preferable that the mask is made of a non-magnetic material because a magnetized pattern can be formed with uniform clarity in any pattern shape and a uniform and strong reproduction signal can be obtained.
[0106]
When a mask containing a ferromagnetic material is used, the magnetic field distribution may be disturbed by magnetization. Due to the ferromagnetic properties, in the case of a pattern shape obliquely inclined from the radial direction of the magnetic disk or an arc-shaped pattern extending in the radial direction, it is difficult to obtain a good quality signal because the magnetic domains do not sufficiently oppose each other at the magnetization transition portion.
The mask is arranged between the light source of the energy beam and the magnetic recording medium. If emphasis is placed on the accuracy of the magnetization pattern, it is preferable that all or part of the mask be in contact with the medium. The effect of laser beam diffraction can be minimized, and a magnetization pattern with high resolution can be formed. For example, when the mask is allowed to stand on the medium, a part of the medium that is not in contact with the medium is formed due to undulation of about several μm. However, the pressure applied to the mask and the medium is 100 g / cm so as not to form indentations or damage to the medium. ² The following is assumed.
[0107]
However, in order to reduce defects and scratches, it is preferable to provide a gap between the mask and the medium at least in a region where the magnetization pattern of the medium is formed. It is possible to prevent the medium and the mask from being damaged and the defects from being generated due to pinching of dust or the like.
When a lubricating layer is provided before the formation of the magnetization pattern, it is particularly preferable to provide a gap between the mask and the medium. This is to minimize the adhesion of the lubricant to the mask. In addition, when high-power energy rays are irradiated while the disk provided with the lubricating layer is in contact with the mask, the lubricant explodes due to rapid vaporization of the lubricant, causing the lubricant to be scattered and the mask to be damaged. This is because there is a risk of doing so.
[0108]
As a method of maintaining the gap between the magnetic pattern forming region of the magnetic recording medium and the mask, any method may be used as long as both can be maintained at a fixed distance. For example, the mask and the medium may be held by a specific device to keep a certain distance. In addition, a spacer may be inserted between the two and at a location other than the magnetization pattern forming region. A spacer may be formed integrally with the mask itself.
[0109]
If a spacer is provided between the mask and the magnetic recording medium at the outer peripheral portion and / or the inner peripheral portion of the magnetic pattern forming region of the medium, the effect of correcting the undulation on the surface of the magnetic recording medium is produced, so that the accuracy of forming the magnetic pattern increases. So good.
The material of the spacer is preferably a hard material. Further, since an external magnetic field is used for pattern formation, it is preferable that the magnet is not magnetized. Preferably, a metal such as stainless steel or copper, or a resin such as polyimide is used. The height is arbitrary, but is usually 0.1 μm to several hundred μm.
[0110]
It is preferable that the minimum gap between the mask and the magnetic recording medium is 0.1 μm or more, whereby damage and defects of the magnetic recording medium and the mask due to pinching of dust and the like can be suppressed. That is, by setting the interval to 0.1 μm or more, it is possible to prevent the magnetic pattern forming portion from unexpectedly contacting the mask due to the undulation of the medium surface. Therefore, since the thermal conductivity of the medium changes at the contact portion, the susceptibility to magnetization is specifically changed accordingly, and there is no problem that a magnetized pattern is not formed as a desired pattern. More preferably, the thickness is 0.2 μm or more. However, the interval is preferably 1 mm or less. Thereby, there is no problem that the diffraction of the energy ray is small and the magnetization pattern is blurred.
[0111]
For example, when an excimer laser (248 nm) is used to transfer a 2 × 2 μm pattern (a pattern having a 2 μm transmitting portion and a 2 μm non-transmitting portion alternately) formed on a mask to a medium, a gap between the mask and the medium is used. The distance needs to be kept to about 25 to 45 μm or less. If the distance is longer than this, the pattern of light and dark of the laser beam is not clear due to the diffraction phenomenon. In the case of a 1 × 1 μm pattern (a pattern having 1 μm transmitting portions and 1 μm non-transmitting portions alternately), the distance is set to about 10 to 15 μm or less.
[0112]
When using a mask, it is preferable to keep the distance to the medium as short as possible within the range of the above conditions. This is because the longer the distance, the more easily the magnetic pattern is blurred due to the wraparound of the irradiated energy beam. In order to improve this and obtain a clearer pattern, by forming a thin transmission part that functions as a diffraction grating outside the transmission part of the mask, or by providing a means that functions as a half-wave plate The wraparound light can be canceled by interference.
[0113]
A magnetic disk may have a magnetic layer formed on both main surfaces of the disk. In such a case, the magnetization pattern of the present invention may be formed on one side at a time, sequentially, or a mask, an energy irradiation system and an external magnetic field may be applied. The application means can be provided on both sides of the magnetic disk to form a magnetization pattern simultaneously on both sides.
If two or more magnetic layers are formed on one surface and you want to form different patterns for each, you can heat each layer individually by focusing the energy beam to be irradiated on each layer and form an individual pattern .
[0114]
When forming a magnetized pattern, between the light source and the mask of the energy beam, or in a region where irradiation between the mask and the medium is not desired, a light shielding plate capable of partially shielding the energy beam is provided. It is preferable to adopt a structure for preventing re-irradiation of energy rays. The light-shielding plate may be any as long as it does not transmit the wavelength of the energy beam used, and may reflect or absorb the energy beam. However, when the energy ray is absorbed, it is heated and easily affects the magnetization pattern. Therefore, a material having good thermal conductivity and high reflectivity is preferable. For example, a metal plate such as Cr, Al, and Fe is used.
[0115]
Preferably, a reduction imaging technique (imaging optical system) is used for the optical system. Patterned energy rays having an intensity distribution corresponding to the magnetization pattern to be formed are reduced and imaged on the medium surface. According to this, the accuracy of the magnetization pattern is not restricted by the patterning accuracy and alignment accuracy of the mask as compared with the case of passing through the mask after narrowing the energy beam with the objective lens, that is, the case of proximity exposure, A fine magnetized pattern can be formed with high accuracy. Further, since the mask and the medium are separated from each other, it is hardly affected by dust on the medium.
[0116]
According to the present technology, an energy ray emitted from a light source is changed in intensity distribution via a mask, and is reduced and imaged on a medium surface through an imaging unit such as an imaging lens. The imaging lens may be referred to as a projection lens, and the reduced imaging may be referred to as reduced projection.
[0117]
Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and can be variously modified and implemented without departing from the spirit of the present invention.
For example, the shielding portion may be formed of a plurality of substances having different colors, and an area having a different color may be used as a mark.
Further, the position where the mark is formed is preferably outside and inside in the radial direction of the mask pattern region, but the mark may be formed in the mask pattern region as long as the region is not formed with the magnetization pattern. Further, a plurality of types of marks formed in each embodiment may be formed on one mask.
Further, the shielding layer is not limited to the inorganic layer, and may be formed of an organic substance such as a resin.
Further, the mask used in the present invention is suitable for the method of forming a magnetic pattern according to the present invention, but also in various other fields, particularly in the field of laser processing that requires a high power and requires a fine pattern. It is possible to use.
[0118]
Incidentally, a projection as a spacer may be formed on the mask according to the present invention. At the time of forming a magnetization pattern, the energy rays transmitted through the mask may interfere or diffract.However, by forming the projections, the distance between the mask and the magnetic recording medium can be made uniform, and the interference of the energy rays and The degree of diffraction can be controlled uniformly. Therefore, it is possible to more precisely control the shape of the region where the energy beam is applied to the magnetic recording medium when the magnetic pattern is formed, that is, the shape of the magnetic pattern.
[0119]
In a mask having projections formed in this way, information is given to the shape and arrangement of the projections, and a projection is formed in a region at a position on a certain circumference or a projection is formed in a specific shape. Alternatively, the protrusion may be used as a mark.
[0120]
Hereinafter, the protrusion as the spacer will be described.
The height of the projection is preferably as low as possible, and the height is preferably 10 μm or less, in order to reduce the distance between the mask and the pattern formation region of the magnetic recording medium and prevent diffusion of incident energy due to diffraction. It is more preferably 7 μm or less, and still more preferably 5 μm or less.
[0121]
When the line width of the pattern to be formed (minimum width of the pattern) is narrower than 1 μm, the influence of light diffraction is particularly large. Therefore, it is desirable to make the height of the projection lower as the line width becomes narrower. .
However, if the height is too low, the magnetic recording medium may come into contact with the undulations. Therefore, the height is preferably 0.01 μm or more. It is more preferably at least 0.1 μm.
[0122]
In the present application, the minimum width of the pattern refers to the narrowest length in the pattern. In the case of a square pattern, the short side is used. In the case of a circle, the diameter is used. In order to keep the space between the mask and the pattern formation region of the magnetic recording medium uniform at least on the concentric circles, it is preferable that the height of the protrusions be uniform on the concentric circles. Therefore, it is preferable that the concentric variation in the height of the protrusion is within ± 20% of the average height. Although there is no particular lower limit, there is practically a variation of ± 3% or more of the average height. The uniformity of the interval can be easily evaluated by observing the number, position, and shape of interference fringes.
[0123]
Preferably, the projections are provided discontinuously. Usually, both the mask and the magnetic recording medium have some undulations. Therefore, when the mask and the magnetic recording medium are brought into contact with each other, the mask and the magnetic recording medium come into contact with each other most stably, that is, at least both of them. It is preferable that they can move with each other so that the intervals on the concentric circles are as constant as possible.
When the mask and the magnetic recording medium are brought into contact by continuous projections on the mask, the contact area is large, so the frictional resistance is high, the relative positions of the two are hard to move, and the movement to maintain the flatness between the mask and the magnetic recording medium May be inhibited. Therefore, the projections are preferably provided discontinuously. That is, a plurality of protrusions are provided discretely. When the mask and the magnetic recording medium come into contact with each other by the discontinuous projections, the frictional resistance between the two becomes low, and the gap between the medium and the mask can be more easily maintained without obstructing the movement in the plane direction.
[0124]
Also, since the projections are discontinuous, there is an air passage, so that the mask and the magnetic recording medium are not attracted. Therefore, there is also an advantage that even if both move in the plane direction according to the undulation, scratches due to friction hardly occur. Further, if the projections are provided continuously, there is a possibility that a portion may be easily peeled off due to stress. Therefore, discontinuity is also preferable in this regard.
Next, a description will be given of a projection shape when a plurality of projections are provided discretely.
The projection shape is preferably substantially circular when viewed from a direction perpendicular to the substrate surface, that is, when the mask is viewed from directly above. This is because such a shape tends to make the projection height uniform. When heating is performed during projection formation, a change in shape due to heat shrinkage (so-called sink marks) may increase the height variation of the projections. However, in substantially circular projections, sink marks occur evenly from the periphery. The projection height tends to be uniform.
The protruding shape may be a concave shape at the center and a raised peripheral portion (a so-called crater shape), but a peak shape at the center and a mountain shape is preferable. This is because the height variation due to the sink marks or the like is uniform and the height can be easily adjusted.
[0125]
It is also preferable that the projection has a shape in which a cross section in a direction perpendicular to the mask surface is substantially rectangular. In other words, the side surfaces of the projection are almost vertically raised, and the top and the bottom of the projection have substantially the same shape. With such a shape, the area of the top portion that actually contacts the magnetic recording medium can be increased with respect to the bottom area of the protrusion, and the position of the support position can be reduced with respect to the misalignment between the mask and the magnetic recording medium. This is because a margin can be provided.
The size of the projection in the surface direction is preferably larger than a certain value in order to withstand the load applied to the mask and the magnetic recording medium. When the projection shape is substantially circular, the diameter is preferably 0.5 μm or more. More preferably, it is 1 μm or more. Further, in order to minimize the change in the interval due to elastic deformation, the diameter is more preferably 5 μm or more. Although there is no particular upper limit on the maximum diameter, the diameter is preferably 1 mm or less in order to reduce the contact resistance between the mask and the magnetic recording medium. When the shape of the projection is not substantially circular, the length of the long side is preferably in the range of the above numerical values.
[0126]
When a plurality of projections are discretely provided, the spacing between the projections is appropriately designed according to the size of the projections, but the spacing between the mask and the medium may be maintained at least substantially concentrically. . However, it is necessary to provide at least three or more in-plane. When the individual projections are considerably large, about three projections may be provided in the plane, but it is usually preferable to provide more projections. When the size of the projection is small, for example, when the diameter is as small as about 1 μm, the bottoms of adjacent projections may be in contact with each other to prevent deformation due to a load.
[0127]
The projection is provided on at least a part of a mask having a mask pattern region that causes shading of an energy ray according to at least a part of a magnetization pattern to be formed.
In a mask having a mask pattern region composed of a combination of a transmission part and a non-transmission part of an energy ray, the projection is provided on the energy-ray non-transmission part in the pattern area and / or a peripheral part of the pattern area.
When the projections are provided in the energy ray non-transmissive portions of the pattern area, the projections can be provided over the entire surface of the pattern area, which is desirable for maintaining a uniform distance between the mask and the magnetic recording medium and supporting them. When provided on the periphery of the pattern area, the mask and the magnetic recording medium do not come into contact with each other in the pattern area. Therefore, the medium and the mask are not damaged, and there is no possibility of increasing the defects of the magnetic recording medium. In addition, since the mask and the magnetic recording medium do not come into contact with each other in the pattern area, undesired heat conduction does not occur in the heating step, which is preferable.
[0128]
It is also a preferable embodiment that the projections are provided on both the energy ray non-transmissive portion in the pattern region and the peripheral portion of the pattern region, and the projection of the non-transmissive portion is formed lower than the peripheral portion. If the distance between the mask and the magnetic recording medium is reduced to, for example, about 3 μm or less, the mask and the magnetic recording medium may be inadvertently contacted in the pattern area, and may be damaged due to friction or the like, resulting in a defect. In particular, in the case where the pressure between the magnetic recording medium and the mask is reduced by suction and fixed, the magnetic recording medium bends and the contact is more likely. Therefore, it is considered that if a low and gentle projection is provided in the pattern area of the mask, the magnetic recording medium is in direct contact with the gentle projection without directly contacting the mask surface, so that the magnetic recording medium is unlikely to become a defect.
Further, when the projection is provided on the peripheral edge of the pattern area, a part of the projection may be provided so as to cover the non-transmissive part in the pattern area. By providing the projections in this manner, the projections can be provided even when the pattern area extends to the vicinity of the end of the magnetic recording medium and it is difficult to provide the projections on the peripheral edge of the pattern area. . Therefore, the pattern area of the magnetic recording medium can be expanded, and a larger-capacity magnetic recording medium can be obtained.
Next, characteristics required for the projection will be described. The projections are required to have certain properties such as lubricity, hardness, heat resistance and solvent resistance. As described above, it is desirable that the friction between the mask and the magnetic recording medium is not too large and that it is relatively movable. Therefore, it is preferable that the protrusions have a certain degree of smoothness.
[0129]
Further, it is preferable that the mask has high lubrication so that the mask and the magnetic recording medium do not stick to each other and the mask can be easily removed. In the industrialization stage, since the mask is placed on the magnetic recording medium by an automatic machine such as a robot, it is preferable that the mask can be easily removed when the mask and the magnetic recording medium are separated in a direction perpendicular to the surface. .
Also, since the mask is used to transfer the magnetization pattern to many magnetic recording media, if the projections are made of a material that is easily plastically deformed, some of the projections will be gradually deformed, and the mask and the magnetic field will move at a specific position. There is a possibility that the interval between the recording media becomes narrow, which may cause the generation of non-concentric distorted interference fringes. Therefore, it is preferable to form the projections with a material having high hardness.
[0130]
For example, it is preferable that the plastic deformation of the protrusion height of the mask after the mask is repeatedly attached and detached on the magnetic recording medium about 10 times is 50% or less of the original height. It is more preferably at most 10%. For industrial use, the content is preferably 10% or less.
Further, the projection is not directly irradiated with the energy beam, but may be installed on the back surface of the non-transmissive portion of the mask, so that the heat in the non-transmissive portion of the mask heated by the energy beam is indirectly transmitted to the projection. Sometimes. Therefore, it is desirable that the protrusions are not easily deformed or decomposed by heat. Preferably, a material having a decomposition temperature of 100 ° C. or higher is used. It is also desirable that the higher the power of the energy ray, the higher the heat resistance of the projection, for example, 100 mJ / cm. ² When the above power is applied, it is preferable that the decomposition temperature is 200 ° C. or higher.
[0131]
When forming the projections, particularly when the projections are formed by a method such as photolithography, the projections are preferably made of a material soluble in a predetermined solvent. However, after the projections are formed, they may be washed with an organic solvent for the purpose of removing dust, particles, and the like attached to the mask. For example, the protrusions may be imparted with solvent resistance by heat treatment or the like after being formed.
[0132]
Next, the configuration of the mask having the protrusions will be described.
As described above, the mask may be a mask having a mask pattern that causes shading of an energy ray according to a magnetization pattern to be formed, a mask having a mask pattern including a transmission part and a non-transmission part of an energy ray, Any type of mask such as a mask having a mask pattern for diffusing lines and a hologram mask can be used.
A mask pattern composed of a transmission part and a non-transmission part of energy rays is formed by, for example, sputtering a metal such as chromium on a transparent base material that is transparent to energy rays such as quartz glass, optical glass and soda lime glass. Then, a photoresist is applied thereon by spin coating or the like, and desired transmission portions and non-transmission portions can be formed by etching or the like. In this case, the portion having the chromium layer on the transparent substrate is the energy ray non-transmissive portion, and the portion of only the master is the transmissive portion. Preferably, a chromium oxide layer is formed on the chromium layer. The chromium oxide layer can be formed only by oxidizing chromium and has a low optical reflectivity, and thus has the effect of reducing the influence of multiple reflection and the like. It is also preferable because it has excellent adhesion to the chromium layer. It is also preferable to apply a non-reflective coating made of a dielectric layer to the mask. Thereby, the energy rays can be more effectively used.
[0133]
As described above, the mask pattern region is formed on the mask, and thereafter, projections are formed on at least a part of the surface of the mask that should face the magnetic recording medium. Hereinafter, a method for forming protrusions on a mask will be described. For example, the following method can be employed.
[0134]
[Method 1]
A radiation-curable or thermosetting resin layer such as polyimide is formed on a mask, and projections are formed on the resin layer by photolithography. In this method, since the thickness of the resin layer is substantially equal to the height of the protrusion, there is an advantage that the height of the protrusion can be accurately, uniformly, and easily controlled by controlling the thickness of the resin layer. In addition, there is an advantage that the formation of the resin layer and the removal by the etching solution can be performed in a short time.
[0135]
When the polyimide resin is a photosensitive polyimide resin, photolithography and etching may be performed as it is after the resin layer is formed, but when the polyimide resin is a non-photosensitive polyimide resin, after forming a photoresist layer on the resin layer, Perform lithography, development, etching, etc.
The method of forming the resin layer is generally coating, and includes a dipping method and a spin coating method. Subsequently, the mask with the resin layer is irradiated with laser light or the like through a projection forming mask having a pattern corresponding to the projection to be formed, to form a latent image. Then, unnecessary portions are removed by etching with an organic solvent or the like to form protrusions.
[0136]
Thereafter, in order to increase the hardness of the projections and improve the solvent resistance of the projections, it is preferable to perform a heat treatment or an ultraviolet irradiation treatment to promote the crosslinking. Examples of the heat treatment include a method using an oven and a method using an infrared lamp. At this time, depending on the material of the resin, the sink at the time of curing is large, and the central portion of the projection may be selectively reduced to form a crater. When a resin having a large sink during curing is used, the shape of the protrusion is preferably substantially circular in order to make the height of the protrusion uniform.
According to this method, a resin layer may be applied thickly to form a high protrusion, but a very thin resin layer is usually difficult to form. For example, a relatively high protrusion having a height of 0.3 μm or more and 10 μm or less may be used. Suitable for forming.
[0137]
[Method 2]
Further, the projections may be formed by an inorganic substance. This is preferable because projections having high hardness are easily formed. Inorganic substances include, for example, metals (including alloys), dielectrics such as oxides and nitrides, and carbon. There are several forming methods as follows.
(Method 2-1)
An inorganic layer is formed on a mask, and projections are formed on the inorganic layer by photolithography. In this method, since the thickness of the inorganic layer is substantially equal to the height of the projection, there is an advantage that the height of the projection can be accurately, uniformly, and easily controlled by controlling the thickness of the inorganic layer.
[0138]
The material of the inorganic layer is not particularly limited as long as it has sufficient hardness and weather resistance. However, a material that is not magnetized is preferable because the influence of an applied external magnetic field is small.
The use of chromium or chromium oxide is preferable because projections can be formed in the same step as the formation of the non-transmissive portion of the mask. As a method for forming the inorganic layer, sputtering, vapor deposition, CVD, plating and the like are generally used. Subsequently, after forming a photoresist layer on the inorganic layer, photolithography is performed. The photoresist layer is irradiated with laser light through a projection forming mask having a pattern corresponding to the projection to be formed, to form a latent image. Subsequently, development is performed, and unnecessary portions of the inorganic layer are removed by etching with an etchant or the like, thereby forming protrusions.
[0139]
According to this method, the height of the projections to be formed can be arbitrarily changed by controlling the thickness of the inorganic layer and the etching amount, so that the method can be applied to various projection heights. For example, it is not less than 0.001 μm and not more than 10 μm. High protrusions can be formed by forming a thick film. However, since the inorganic layer can be easily formed thinner than a resin, low protrusions of 0.001 μm or more and 3 μm or less, which are difficult to form by a method using a resin, can be easily formed.
[0140]
(Method 2-2)
An inorganic layer is formed at a position where the projection of the mask is to be formed, and the projection is formed. That is, a shielding plate having holes corresponding to the shape of a projection to be formed is arranged on a mask, and an inorganic layer is formed by sputtering, vapor deposition, or the like. This method has the same advantages as (method 2-1), and furthermore, since projections can be formed very easily and there is no need for a wet process, there is a very high possibility that foreign matter remains on the mask. This is preferable because the magnetic recording medium is less likely to be contaminated during transfer of the magnetization pattern. That is, photolithography of the inorganic layer is unnecessary, and subsequent steps of removing and washing the resin are not required. Also, application of the resin is not required, and only the inorganic layer is formed.
Further, in this method, since the thickness of the inorganic layer is substantially equal to the height of the protrusion, there is an advantage that the height of the protrusion can be controlled accurately, uniformly, and easily by controlling the thickness of the inorganic layer.
[0141]
The material of the inorganic layer, the film forming method, and the like are the same as in (Method 2-1). However, in this method, at the time of forming the inorganic layer, the shielding plate is disposed between the sputtering target or the evaporation source and the mask. The shape of the projection can be controlled by the shape of the hole of the shielding plate, and may be band-shaped or discontinuous.
The shielding plate is subjected to mechanical processing such as punching, for example, according to the projection shape to be manufactured. The material of the shielding plate is not particularly limited as long as it is easy to process and has a certain durability. For example, a metal foil such as stainless steel (SUS), brass or copper, or a resin film such as polyimide is used. Although the thickness is not particularly limited, it is preferably 10 μm or more from the viewpoint of workability and durability. On the other hand, if the thickness is too large, it is difficult to form an inorganic film through the hole, and it is difficult to process the inorganic film.
[0142]
This method is suitable for forming a projection having a relatively large bottom area because the shielding plate is mechanically processed according to the projection shape. The projection having a large bottom area is, for example, 0.2 mm or more in diameter for a circle, and 0.2 mm or more for one side for a square. Since large projections are physically stronger, it is preferable in terms of strength to support the medium with a small number of large projections than to support the medium with many small projections.
Further, in this method, in the hole of the shielding plate, a portion that is shaded by the thickness of the shielding plate is difficult to form a film, so that a gentle projection with an inclined side surface is likely to be formed. However, if the shape of the hole in the shielding plate is changed in the thickness direction to be wider toward the upper side, it is considered that a projection having a relatively rectangular side surface with a substantially rectangular cross section perpendicular to the mask surface can also be formed.
[0143]
That is, in this method, a gentle projection having a large bottom area is easily formed. In the case of a hard disk, the distance between the pattern area and the outer peripheral edge of the disk is very small, for example, 0.3 mm or less. Therefore, when forming a gentle projection having a peak at the periphery of the pattern area, the base of the projection is formed in the pattern area. Often spread to. In such a case, it is preferable to form the projections so that the skirt area is widened in the non-transmissive portion in the pattern region.
Further, it is preferable that the protrusion has at least a large length in the disk radial direction so that the disk can be supported even if the alignment between the disk and the mask is slightly shifted. Depending on the shape of the pattern in the pattern area, the length of the protrusion in the circumferential direction of the disk may not be able to be increased.
[0144]
According to this method, the height of the projections formed can be changed arbitrarily by controlling the thickness of the inorganic material layer, so that the method can be applied to various projection heights. For example, it is not less than 0.001 μm and not more than 10 μm. In addition, since the inorganic layer can be easily formed thinner than a resin, a low protrusion of 0.001 μm or more and 3 μm or less, which is difficult to form by a method using a resin, can be easily formed.
It is also easy to change the height of the projection depending on the location by changing the shape or position of the hole of the shielding plate during the sputtering. In addition, it is preferable that a high projection can be easily formed only by forming a thick film without an etching step.
[0145]
(Method 2-3)
A projection made of an inorganic substance is formed on the mask by a so-called lift-off method. That is, if the photoresist layer on the mask is formed with irregularities by photolithography, an inorganic layer is formed thereon, and then the photoresist layer is removed, the inorganic layer remains as a protrusion only in the portion where there is no photoresist.
explain in detail. A photoresist is applied to the mask to a predetermined thickness, and a laser beam is irradiated and developed according to the position and shape of the projection to be formed, and a part of the photoresist is removed to form irregularities. After forming a metal layer according to the height of the projection to be formed thereon, it is immersed in, for example, a photoresist removing liquid. Then, the photoresist layer is removed and the metal layer formed thereon is removed, so that only the metal layer formed in a place where there is no photoresist remains as a protrusion.
In this method, since the thickness of the metal layer is substantially equal to the height of the projection, there is an advantage that the height of the projection can be accurately, uniformly, and easily controlled by controlling the thickness of the metal layer.
[0146]
The material of the inorganic layer, the film forming method, and the like are the same as in (Method 2-1). For example, a strong alkaline solution or the like is used as the photoresist removing solution.
In this method, the shape of the protrusions can be controlled by the shape of the unevenness formed on the photoresist layer, and may be band-like or discontinuous. Since photolithography is performed, it is suitable for forming a projection having a smaller bottom area as compared with (Method 2-2). The protrusion having a small bottom area is, for example, less than 0.2 mm in diameter in the case of a circle, and less than 0.2 mm in one side in the case of a square.
It is preferable that a small protrusion has a high degree of freedom in a place where it can be formed and can be formed in a narrow region. The distance between the pattern area and the outer peripheral edge of the disk can also be provided at the peripheral edge of the hard disk, which is very narrow, for example, 0.3 mm or less.
In addition, since projections are formed by photolithography, alignment with a pattern can be easily performed more accurately than in the case of (method 2-2). In some cases, the pattern and the projection can be formed at the same time, and the process can be significantly shortened. Further, according to the lift-off method, it is easy to form a projection having a substantially rectangular cross section in a direction perpendicular to the mask surface, that is, a projection having a steep side surface. Therefore, even if the bottom area is the same, a projection having a larger top area can be easily formed, and the disc can be supported even if the disc and the mask are slightly misaligned. Further, it is preferable that the length of the protrusion is large in the radial direction of the disk. As a result, it is possible to allow a margin for misalignment between the mask and the disk.
[0147]
According to this method, the height of the projections formed can be changed arbitrarily by controlling the thickness of the inorganic material layer, so that the method can be applied to various projection heights. For example, it is not less than 0.001 μm and not more than 10 μm. In addition, since the inorganic layer can be easily formed thinner than a resin, a low protrusion of 0.001 μm or more and 3 μm or less, which is difficult to form by a method using a resin, can be easily formed.
By repeating the lift-off method several times, the height of the projection can be changed depending on the location. In addition, it is preferable that high projections can be easily formed only by forming a thick film without an etching step of the inorganic layer.
[0148]
[Method 3]
A liquid resin is dropped on a portion of the mask where the projection is to be formed to form the projection. This method does not require application of the entire surface of the resin, and has the advantage that projections can be formed very easily because photolithography is not required and subsequent resin removal and cleaning steps are not required.
After the radiation-curable or thermosetting resin is dropped, it is preferable to cure the resin by heating with an oven or an infrared lamp, or by irradiating a laser beam or the like, in order to increase the hardness of the projections and improve the solvent resistance of the projections.
[0149]
At this time, depending on the material of the resin, the sink at the time of curing is large, and the central portion of the projection may be selectively reduced to form a crater. When a resin having a large sink during curing is used, the shape of the protrusion is preferably substantially circular in order to make the height of the protrusion uniform.
In this method, the height and size of the protrusion can be controlled by adjusting the amount and viscosity of the resin. In order to form a high projection, the amount of the resin may be increased and the viscosity may be increased to be dropped. For example, it is suitable for forming a relatively high projection having a projection height of 0.3 μm or more and 10 μm or less.
[0150]
[Method 4]
A projection is formed by forming a radiation-curable or thermosetting resin layer in which inorganic / organic fine particles are dispersed on a mask. Since this method does not require photolithography and does not require a subsequent resin removal and cleaning step, there is an advantage that projections can be formed very easily.
The method of forming the resin layer is generally coating, and includes a dipping method and a spin coating method. After application, it is preferable to cure the resin by heating with an oven or an infrared lamp, or by irradiating a laser beam, etc., in order to increase the hardness of the projections and improve the solvent resistance of the projections.
[0151]
The type of the particles is not limited as long as the particles have a sufficient hardness. However, for example, particles such as glass, silicon, and resin are preferably used because they have little effect on an external magnetic field to be applied. The size of the particles may be selected according to the size of the projection to be formed, but is usually about 0.3 μm or more and 10 μm or less. In order to make the projection height uniform, the particles to be added are preferably spherical.
In this method, the height and size of the projections can be controlled by adjusting the size, shape and amount of the particles, the amount and viscosity of the resin, and the like. This method is suitable for forming a relatively high projection having a projection height of, for example, 0.3 μm or more and 10 μm or less.
[0152]
[Method 5]
A base material constituting the mask is irradiated with an energy ray having a high energy density to deform the base material to form a projection. Alternatively, a projection is formed by irradiating an energy ray having a high energy density after forming a processing layer on a base material to deform the processing layer. Usually, quartz glass, soda lime glass, or the like is used as the substrate. Any material that can be deformed by irradiation with energy rays and has sufficient hardness may be used as the processing layer material.For example, when chromium or chromium oxide, which is a material for forming the non-transmissive portion, is used, the formation of the non-transmissive portion and Protrusions can be formed in the same step, which is preferable. In this case, chromium, chromium oxide, or the like may be formed also on the periphery of the pattern region.
[0153]
This method has an advantage that projections can be formed very easily because resin application and photolithography are not required, and subsequent resin removal and washing steps are not required. In addition, since the material of the projection is, for example, quartz glass as a base material of the mask, there is an advantage that a projection having high hardness can be easily formed. Further, low projections having a height of 1 μm or less can be easily formed by selecting laser irradiation conditions. A height of several to several tens of nm is also possible. Therefore, for example, it is suitable for forming a relatively low protrusion having a protrusion height of 0.001 μm or more and 3 μm or less.
[0154]
In this method, a laser beam is applied to the base material or the processed layer of the mask. Lasers suitable for use include a carbon dioxide laser (wavelength 10.6 μm), an excimer laser (157, 193, 248, 308, 351 nm), a fundamental wave (1064 nm) of a YAG Q-switched laser, a second harmonic (532 nm), A third harmonic (355 nm) or a fourth harmonic (266 nm), an Ar laser (488 nm, 514 nm), a laser diode (780, 980, 820 nm) and the like can be given.
When the projections are formed directly on glass, quartz, or the like as the base material of the mask, it is preferable to use a light source having a long wavelength, such as a carbon dioxide laser (wavelength 10.6 μm).
[0155]
When irradiating a laser to the non-transmissive part of the pattern area of the mask or the peripheral part of the pattern area to heat and deform the processing layer to form protrusions, the energy beam used is a laser beam with a wavelength that is absorbed by the processing layer. For example, a fundamental wave (1064 nm), a second harmonic (532 nm), a third harmonic (366 nm), a fourth harmonic (266 nm), an Ar gas laser (514, 488 nm), an excimer laser (157, 193) of a YAG laser can be used. , 248, 308, and 351 nm), and a laser diode (780, 980, and 820 nm).
The laser to be irradiated has a pulse shape. Even when a pulse oscillation laser is used, a continuous oscillation laser is pulsed by an acousto-optic device (AO), an electro-optic device (EO), a mechanical shutter, or the like. It doesn't matter. Irradiation with a pulsed laser facilitates formation of a substantially circular projection.
[0156]
The pulse width of the laser to be irradiated may be short when the energy density generated by the light source is high, but is preferably 1 nsec or more in order to sufficiently generate heat in the processed layer. Although a light source having a low energy density can form a projection by making the pulse width sufficiently large, the pulse width is preferably about 1 second or less, and more preferably 100 msec or less, in order to avoid unnecessarily extending the processing time.
As a method of forming the projection, a laser beam is irradiated on a predetermined place while rotating the mask on a rotating body such as a spindle, and a laser beam is irradiated on a predetermined place while moving the mask on an XY stage or the like. May be.
[0157]
The protrusion formed as described above may be covered with another layer. For example, a carbonaceous layer such as hydrogenated carbon or amorphous carbon, or a fluorine-based resin layer such as Teflon (registered trademark) is used. The carbon layer can be formed by sputtering, CVD, or the like, and has high hardness, so that projections can be prevented from being scraped and lubricity can be imparted. Fluorinated resins can also impart lubricity.
When the projection is made of a metal such as chromium, it is preferable to cover the projection with another layer in order to prevent the contamination of the medium by corrosion.
[0158]
By using the mask on which the protrusions are formed as described above, the distance between the magnetic recording medium and the mask can be made uniform when forming the magnetic pattern. As a result, the degree of diffraction of the energy ray transmitted through the mask pattern can be made uniform on the concentric circle of the mask, and the shape of the heated area of the magnetic recording medium can be precisely controlled. A magnetization pattern shape can be formed.
[0159]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples unless it exceeds the scope of the gist.
[0160]
(Example 1)
A plurality of projections were formed on the outer peripheral side and inner peripheral side of the region where the mask pattern was formed, on the surface of the magnetized pattern shape defining mask. The procedure at that time will be described below.
[0161]
First, a 100-nm-thick Si film was formed by a sputtering method on a substrate formed of quartz glass in a disk shape having a diameter of 120 mm and a thickness of 2.3 mm to form a Si thin film serving as a non-transmissive portion. The conditions for film formation were as follows: Ar was used as a sputtering gas, and sputtering was performed at a sputtering gas pressure of 0.6 Pa and a power of 500 W for 53 seconds.
[0162]
Next, a photoresist MCPR-2200X was applied to a thickness of 200 nm on the surface of the formed Si thin film by spin coating to form a photoresist thin film.
Of the area where the photoresist thin film is applied on the substrate surface, an area where a mask pattern having a radius of 19.7 mm to a radius of 46.7 mm is to be formed; Exposure was performed by irradiating a Kr laser (wavelength: 413 nm) to a region where an alphanumeric character as a mark was to be formed. The alphanumeric characters as marks were formed with a side size of 2 mm.
[0163]
A method of exposing will be described. The substrate was set so that the surface on the side where the Si thin film was formed on the turntable faced upward in the direction of gravity, and the turntable was rotated. With the substrate rotating together with the turntable, the substrate was exposed to a Kr laser from the objective lens. The exposure was performed while the objective lens was moved in the radial direction of the turntable, and the Kr laser was exposed so that the photoresist thin film on the substrate surface was exposed spirally or concentrically. The amount of Kr laser light is adjusted by a power control electro-optical element (EO) so as to have an appropriate amount of light according to the linear velocity determined by the rotation speed and the radial position of the turntable, and then the shape of the mask pattern is obtained. The timing of exposure by the modulation electro-optical element (EO) is controlled so as to be interrupted accordingly.
[0164]
The mask pattern includes a mask pattern called a timing pattern or a preamble pattern, a preamble pattern, a jig pattern and a zag pattern formed zigzag along the timing pattern, and a gray code pattern indicating a radial position on the mask surface. However, the timing pattern, the jig pattern and the zag pattern were formed to have a width of about 0.5 to 2 μm, and the gray code pattern was formed to have a larger width.
[0165]
Also, the mask patterns are arranged in the radial direction of the mask to form a region called a spoke. The spokes are formed in an arc shape extending in the radial direction, and the arcs are formed so as to be arcs equidistant from a point outside the mask. The point outside the mask is a fulcrum of a read head for reading a magnetic recording medium manufactured using a mask that is being manufactured, and an arc equidistant from this fulcrum corresponds to an area where the read head moves.
After the exposure as described above, development was performed to remove the photoresist in the exposed region of the photoresist thin film.
[0166]
Next, the Si thin film in the area where the photoresist thin film was removed was removed by RIE. RIE conditions are gas SF ₆ RIE was performed at a flow rate of 30 seconds and a power of 50 W for 62 seconds. At this time, in the region where the photoresist thin film is formed, the Si thin film is protected by the photoresist, so that Si is not removed by RIE.
[0167]
The mask was immersed in Nagase resist stripping solution N303C, the photoresist thin film on the mask surface was removed, and the mask was dried.
On the surface of the mask on which the Si thin film was formed, SiO 2 was formed by sputtering. ₂ Was formed with a thickness of 30 nm. The conditions at the time of this film formation are Ar / O as a sputtering gas. ₂ = 7/3, and sputtering was performed at a sputtering gas pressure of 0.6 Pa and a power of 500 W for 73 seconds.
[0168]
By the above-described process, a mask pattern is formed in a region having a radius of 19.7 mm to 46.7 mm, and a mark which can be visually confirmed by alphanumeric characters is formed in a region having a radius of 48.0 mm to 50.0 mm. The mask for shape specification was able to be manufactured.
Even if the pattern formation of the mark part cannot be precisely performed for some reason during the manufacturing, the shape of the mark is formed by exposing the photoresist along the circumferential direction of the mask as described above. For example, characters and numbers are formed to be slightly bent, so that there is no problem in specifying information. However, when the mark is formed in a shape such as a two-dimensional code, if the shape of the mark is shifted, information may not be able to be specified, and correction may be required.
[0169]
(Example 2)
120.00 ± 0.20 mm in diameter, 2.3 ± 0.1 mm in thickness, parallelism between front and back surfaces (excluding TTV: Total Thickness Variation) excluding 3 mm around 6 mm or less, surface flatness excluding 3 mm around (surface TIR) Also called: Total Indication Reading: 2 μm or less, back flatness excluding 3 mm around (backside TIR): 6 μm or less, surface unevenness (Ra) at 1 μm × 1 μm square: 0.18 nm or less, coefficient of thermal expansion at 15 ° C. to 200 ° C. 6.5 × 10 ^-7 Chamfers (also called chamfers) having the following shapes were formed on the outer periphery of the following disk-shaped substrate made of quartz.
[0170]
(Example 2-1)
The radial width of the chamfered portion measured in a direction parallel to the front or back surface of the substrate (hereinafter referred to as chamfer width) 0.45 ± 0.15 mm, the angle between the chamfered surface and the front or back surface (hereinafter, referred to as the chamfer width). A chamfer having a chamfer angle of 45 ° ± 2 ° and a finish Rrms ≦ 0.03 μm of the end face and the chamfer was formed on the front and back surfaces of the mask. Even when a photoresist thin film was formed on this mask, a ski jump shape was not formed at the end of the mask.
[0171]
(Example 2-2)
A first chamfer having a chamfer width of 1.0 mm ± 0.1 mm and a chamfer angle of 10 ° ± 1 ° is formed on the front surface and the back surface of the substrate, and a chamfer width is formed at a corner formed by the first chamfer and the end surface of the substrate. A second chamfer of 0.10 mm ± 0.03 mm was formed, and the corner formed by the end face and each chamfer was finished at Rrms ≦ 0.03 μm. Even when a photoresist thin film was formed on this mask, a ski jump shape was not formed at the end of the mask. In particular, when a liquid having a higher viscosity was applied, in the present example in which the slope of the chamfered portion was gentler, the occurrence of the ski jump shape could be suppressed more than in Example 2-1.
[0172]
(Example 2-3)
A fan-shaped notch was provided on the back surface of the substrate. The maximum value of the chamfer width is 3.0 mm ± 1.0 mm, the chamfer angle is 10 ° ± 2 °, the sector angle is 30 °, and the corner formed by the end face and each chamfer is finished with Rrms ≦ 0.03 μm. Was. By using this chamfer as a mark, the circumferential position of the mask could be specified.
[0173]
【The invention's effect】
According to the present invention, since marks for specifying various types of information on the mask are formed integrally with the mask, the mask can be formed without impairing the adhesion to the magnetic recording medium when forming the magnetization pattern. Can be easily specified by the mask alone. In addition, the mark can be stably used without any trouble caused by cleaning or irradiation with energy rays (claim 1).
[0174]
At this time, the mark is used to identify at least one of information on the front and back of the mask, the position on the circumference of the mask, the type of the mask, and the mask pattern forming direction in the plane of the mask. If this is the case, it becomes possible to appropriately specify such information necessary for inspection, management and use of the mask (claim 2).
[0175]
Further, by forming the mark outside the mask pattern region, it is possible to prevent the magnetization pattern from being changed by the mark when the magnetization pattern is formed on the magnetic recording medium using the mask. Claim 3).
[0176]
Further, the mask is composed of a substrate that transmits energy rays and a shielding layer that does not transmit energy rays, and a part of the shielding layer is opened in a shape corresponding to the magnetization pattern, and this is used as a mask pattern area. Accordingly, the present invention can be applied to a commonly used high-definition mask (claim 4).
[0177]
Further, in the mask having the above-described structure, a part of the substrate or the shielding layer is deformed to form a mark, so that the mark can be formed integrally with the substrate or the shielding layer in the same process. The formation is facilitated, and the stability of the mark can be enhanced (claim 5).
[0178]
Further, when spokes, which are a set of mask patterns, are formed radially on the shielding layer, at least one of the plurality of spokes extends radially inward or outward of the mask relative to other spokes. By using this as a mark, it is possible to easily specify a position in the circumferential direction on the mask surface, such as the position of an index pattern (claim 6).
[0179]
Further, a notch having an angle parallel to the mask pattern is formed at the inner or outer end of the spoke, and this is used as a mark, so that, for example, when the mask is inspected by the AFM, the surface of the mask 1 can be formed. It is possible to easily adjust the direction in the inside (claim 7).
[0180]
Further, the shielding layer and the mark are formed on the substrate in the same step (claim 8), or the shielding layer is provided on the substrate on which the mark has been formed in advance (claim 9), whereby the manufacturing process is performed. It is possible to form a mark efficiently and reliably without increasing the number of marks.
[Brief description of the drawings]
FIG. 1 is a drawing showing an outline of a mask for defining a magnetic pattern shape as a first embodiment of the present invention, and FIG. 1A is a front view of a mask for defining a magnetic pattern shape as a first embodiment of the present invention. FIG. 1B is an enlarged cross-sectional view of the magnetization pattern shape defining mask shown in FIG.
FIG. 2 is a front view illustrating an outline of a mask for defining a magnetization pattern shape according to a second embodiment of the present invention.
FIG. 3 is a front view schematically showing a mask for defining a magnetic pattern shape according to a third embodiment of the present invention.
FIG. 4 is a front view showing an outline of a mask for defining a magnetic pattern shape according to a fourth embodiment of the present invention.
FIG. 5 is a cross-sectional view of a main part of a substrate for describing a manufacturing process of a mask for defining a magnetic pattern shape according to the present invention.
FIG. 6 is a front view showing an outline of a mask for defining a magnetic pattern shape as a conventional example.
7A and 7B are diagrams showing marks formed on a mask for defining a magnetic pattern shape according to the present invention. FIG. 7A is a diagram showing a bar code, FIG. 7B is a diagram showing a PDF417, and FIG. FIG. 7C shows a QR code, and FIG. 7D shows a data code.
FIGS. 8A and 8B are views for explaining a magnetic pattern forming method of the present invention, wherein FIG. 8A is a plan view and FIG. 8B is a cross-sectional view.
[Explanation of symbols]
1 Mask
2 Mask pattern
3 spokes
4 Substrate
5 Inorganic layer
6 Notch on board
7. Spoke protruding part
8 symbol
9 Notch
10. Photoresist thin film
11 Magnetic disk
12a, 12b, 12c, 12d permanent magnet
13 Shade plate
13a Opening
14 Mask
15 Energy rays
17 Spacer
18a, 18b, 19a, 19b, 19c, 19d Air-core coil (electromagnet)
21 DC power supply
22 capacitors
23 Thyristor
24 Trigger generator
25 Delay device
26 Energy source
27 chamfer

Claims (9)

Heating the magnetic layer of the magnetic recording medium by irradiating it with energy rays and applying an external magnetic field to form a magnetic pattern on the magnetic layer, the mask defining the shape of the magnetic pattern,
According to the shape of the magnetization pattern to be formed, the magnetic layer has a mask pattern region in which a mask pattern that causes local intensity of irradiation of the energy beam to the magnetic layer is formed,
A mark for specifying information on the mask, wherein the mark is formed integrally with the mask, the mask for defining a magnetization pattern shape. The mark is at least one of information on the front and back of the mask, the type of the mask, the position on the circumference of the mask, and the forming direction of the mask pattern in the plane of the mask as the information on the mask. 2. The mask for defining a magnetized pattern shape according to claim 1, wherein the mask is used to specify the pattern. The mask for defining a magnetization pattern shape according to claim 1 or 2, wherein the mark is formed outside the mask pattern region. A disk-shaped substrate that transmits energy rays and a shielding layer that is provided on the substrate and does not transmit energy rays, and
4. The mask pattern region according to claim 1, wherein the mask pattern region is formed by opening at least a part of the shielding layer to transmit energy rays in a shape corresponding to the magnetization pattern. The mask for defining a magnetization pattern shape according to claim 1. The mask according to claim 4, wherein the mark is formed by deforming or processing a part of the substrate and / or the shielding layer. In the shielding layer, a plurality of spokes that are a set of the mask patterns are formed in a radial direction,
The mark is formed as a portion formed by extending at least one of the plurality of spokes inward and / or outward in the radial direction of the mask from other spokes. The mask for defining a shape of a magnetic pattern according to claim 4 or claim 5. In the shielding layer, spokes that are a set of the mask patterns are formed in a radial direction,
7. The mark according to claim 4, wherein the mark is formed as a notch at an angle parallel to a mask pattern at an inner end and / or an outer end of the plurality of spokes. 8. 13. The mask for defining a magnetization pattern shape according to claim 1. 8. The method according to claim 4, wherein the shielding layer and the mark are formed on the substrate in the same step. The method according to claim 4, further comprising a step of providing the shielding layer on the substrate on which the marks have been formed in advance.

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