JP2006309879A - Information recording medium, recording and reproducing device, and stamper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording medium having a servo pattern enabling a magnetic signal to securely be read over the entire area from an inner peripheral side to an outer peripheral side. <P>SOLUTION: The servo pattern is formed of an unevenness pattern 20 on one surface side of a glass material 11 and a data track pattern is formed by providing a concentric or spiral data recording track on the one surface side. The unevenness pattern 20 constituting the servo pattern has its unit projection portion length and unit recessed portion length defined so that the value obtained by dividing the unit projection portion length in the rotating direction of the glass base material 11 by the distance from the center of the data track pattern and the value obtained by dividing the unit recessed portion length in the rotating direction by the distance from the center, both decrease from the inner peripheral side toward the outer peripheral side, and also has the unit projection portion length and unit recessed portion length defined so that the unit recessed portion length is less than the unit projection portion length at the same radius position where the distance from the center is equal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an information recording medium on which a servo pattern is formed by a concavo-convex pattern, a recording / reproducing apparatus including the information recording medium, and a stamper for manufacturing the information recording medium.

  In the process of manufacturing a semiconductor element, an information recording medium, etc., a stamper with a nanometer-sized uneven pattern is pressed against the resin layer on the substrate to transfer the uneven shape of the stamp onto the resin layer. US Pat. No. 5,772,905 discloses a nanoimprint lithography method for forming a nanometer-sized uneven pattern (an imprint method for forming a nanometer-sized uneven pattern: hereinafter also referred to as “imprint method”). In this imprint method, first, a stamper (mold) in which a concavo-convex pattern having a nanometer size (for example, a minimum width of about 25 nm) is formed on the transfer surface is manufactured. Specifically, a desired pattern is drawn using an electron beam lithography apparatus on a resin layer formed so as to cover a thin film (molding layer) such as silicon oxide formed on the surface of a silicon substrate. Thereafter, a thin film is etched using a resin layer as a mask by a reactive ion etching apparatus to form a concave / convex pattern having a plurality of features within the thickness of the thin film. Thereby, a stamper is manufactured.

Next, for example, polymethyl methacrylate (PMMA: resin material) is spin-coated on the surface of a silicon substrate to form a resin layer (thin film layer) having a thickness of about 55 nm. Subsequently, after heating both the laminate of the base material and the resin layer, and the stamper, each convex portion of the stamper is pressed against the resin layer on the base material. At this time, the resin material at the portion where the convex portion of the stamper is pushed moves toward the concave portion of the stamper, whereby concave portions (regions) are formed (transferred) at the portion where the convex portion is pushed. Next, the laminate with the stamper pressed is allowed to stand until it reaches room temperature (after cooling), and then the stamper is peeled from the resin layer. Thereby, each convex part in the uneven | corrugated pattern of a stamper is transcribe | transferred to a resin layer, and the uneven | corrugated pattern of nanometer size is formed on a base material (resin layer). Thereafter, the substrate is etched using the resin layer having the concavo-convex pattern as a mask, thereby forming a plurality of recesses in the substrate. Therefore, by forming a recess in the resin layer on the information recording medium base material by the technique (imprint method) as described above, an etching process using the resin layer as a mask has a nanometer-sized uneven pattern. An information recording medium can be manufactured.
US Pat. No. 5,772,905

  However, the information recording medium manufactured according to the conventional imprint method (manufacturing method) has the following problems. That is, in the conventional manufacturing method, the concave portion is formed in the resin layer by pressing the convex portion of the stamper into the resin layer formed on the substrate, and the concave / convex pattern is formed, and the resin layer on which the concave / convex pattern is formed is used as a mask. The uneven pattern is formed on the substrate by etching the substrate. However, when, for example, a discrete track type magnetic recording medium (information recording medium) is manufactured in accordance with this manufacturing method, the amount of pressing of the convex portion (the convex portion of the stamper) into the resin layer is insufficient in the outer peripheral region of the magnetic recording medium. As a result, a large amount of the resin material may remain at the bottom of the recess in the uneven pattern formed (transferred) on the resin layer. As a result, when the magnetic recording medium is manufactured according to the conventional manufacturing method, the concave / convex pattern is formed on the magnetic recording medium with high accuracy due to excessive expansion of the concave portion during the removal process of the resin material remaining on the bottom of the concave portion. May be difficult. In the following description, the resin material left between the bottom surface of the recess formed in the resin layer by pressing the stamper and the base material is also referred to as “residue”.

  Specifically, for example, as shown in FIG. 15, the magnetic disk 10 x manufactured according to the above manufacturing method includes a track pattern region At in which an uneven pattern 20 t formed of a plurality of concentric recording tracks is formed, The servo pattern area Asx on which the concave / convex pattern 20sx for tracking servo is formed is defined and manufactured so as to be alternately arranged in the rotation direction of the magnetic disk 10x (direction of arrow R shown in the figure). In this case, in a recording / reproducing apparatus equipped with this type of magnetic recording medium, it is common to rotate the magnetic recording medium at a constant angular velocity during recording / reproduction. Therefore, in this magnetic disk 10x, the servo pattern area Asx along the rotation direction of the magnetic disk 10x is proportional to the length on the magnetic disk 10x that is allowed to pass under a magnetic head (not shown) per unit time. Is defined to be longer as it goes from the inner circumference side toward the outer circumference side (so that the servo pattern area Asx becomes wider toward the outer circumference side). Specifically, as shown in FIGS. 16 and 17, in proportion to the distance from the center O (see FIG. 15) of the concave / convex pattern 20t, rather than the length along the rotation direction of the inner peripheral servo pattern region Asxi, The length along the rotation direction of the outer peripheral servo pattern region Asxo is longer.

  In this type of magnetic disk, the length of the unit convex portion (magnetic) along the rotation direction of the convex portions 21sxi and 21sxo (hereinafter also referred to as “convex portion 21sx” when not distinguished) in the servo pattern area Asx (uneven pattern 20sx). Reference lengths detected as “there is one convex portion” when reading a signal: L1xi and L1xo in FIGS. 16 and 17 and concave portions 22sxi and 22sxo (hereinafter also referred to as “concave portion 22sx” when not distinguished) The unit recess length along the rotation direction (reference lengths detected as “one recess is present” when reading a magnetic signal: L2xi, L2xo in FIGS. 16 and 17) is from the inner peripheral area Axi of the magnetic disk 10x. It is defined so that a ratio of 1: 1 (ratio of unit concave portion length to unit convex portion length is 1) in the entire area up to the outer peripheral side region Axo. To have. Accordingly, in this magnetic disk 10x, the distance L2xo of the concave portion 22sxo in the outer servo pattern area Asxo is more distance from the center O of the concave / convex pattern 20t than the length L2xi of the concave portion 22sxi in the inner peripheral servo pattern area Asxi. Is longer in proportion to

  On the other hand, the stamper (see FIGS. 18 and 19) for manufacturing the magnetic disk 10x is provided with a concavo-convex pattern 39x in which the concavo-convex positional relationship is reversed with respect to the concavo-convex patterns 20t and 20sx to be formed on the magnetic disk 10x. Has been. Therefore, as shown in FIGS. 18 and 19, in the stamper for manufacturing the magnetic disk 10x, in the rotational direction of the convex portion (the convex portion 39ax shown in FIG. 18) corresponding to the concave portion 22sxi in the inner servo pattern area Asxi. The length L6xo along the rotation direction of the convex portion (the convex portion 39ax shown in FIG. 19) corresponding to the concave portion 22sxo in the outer peripheral servo pattern region Asxo is longer than the along length L6xi.

  In this case, in the conventional manufacturing method, the uneven pattern 39x is pressed against the resin layer with a substantially uniform pressing force over the entire area of the stamper. Therefore, as shown in FIG. 18, in the portion where the convex portion 39ax having a relatively short length L6xi along the rotation direction is formed (the portion where the concave / convex pattern 20sx of the inner peripheral servo pattern region Asxi is formed), As a result of the resin material in the portion where the convex portion 39ax is pushed in smoothly moving into the concave portions 39bx and 39bx of the stamper, the convex portion 39ax can be pushed into the resin layer sufficiently deeply. As a result, the uneven pattern 41x having a sufficiently thin resin layer thickness T1 between the tip of the convex portion 39ax and the base material (the bottom portion of the concave portion 41bx) can be formed on the base material. On the other hand, as shown in FIG. 19, a portion where a convex portion 39ax having a relatively long length L6xo along the rotation direction is formed (a portion where the concave and convex pattern 20sx of the outer peripheral servo pattern region Asxo is formed). Then, it becomes difficult for the resin material at the portion where the convex portion 39ax is pushed into to move into the concave portions 39bx and 39bx of the stamper. As a result, it becomes difficult to push the convex portion 39ax deeply into the resin layer. . As a result, a residue having a thickness T2 is generated between the tip of the convex portion 39ax and the base material (the bottom portion of the concave portion 41bx).

  On the other hand, when the substrate is etched using the resin layer on which the concavo-convex pattern 41x is formed as a mask, the residue on the bottom surface of the concave portion 41bx in the concavo-convex pattern 41x needs to be removed by an etching process or the like (removal described above) processing). In this case, as described above, the thickness T1 of the residue where the convex portions 39ax, 39ax,... Along which the L6xi along the rotational direction is short is pushed into the convex portions 39ax, 39ax,. It is sufficiently thinner than the thickness T2 of the residue at the pushed-in portion. Therefore, when the etching process (removal process) is performed for a sufficient time so as to reliably remove the residue of the thickness T2 in the outer peripheral area that will be the outer peripheral servo pattern area Asxo later, the removal of the residue of the thickness T2 is performed. Prior to completion of the process, removal of the residue of thickness T1 is completed in the inner peripheral region. As a result, at the portion where the residue of thickness T1 is removed (the portion of the recess 41bx having a short length along the rotation direction), the etching is continued until the removal of the residue of thickness T2 is completed, whereby the inner wall ( The side surface of the convex portion 41ax) is eroded and the concave portion 41bx expands excessively. For this reason, in the magnetic disk 10x manufactured according to the conventional manufacturing method, it is difficult to form the recess 41bx having a desired width, and therefore the width of the recess 22sxi in the inner peripheral servo pattern region Asxi. May become excessively wide, which may make it difficult to reliably read magnetic signals.

  The present invention has been made in view of such problems, and an information recording medium and a recording / reproducing apparatus having a servo pattern capable of reliably reading a magnetic signal in the entire region from the inner periphery side to the outer periphery side, and The main object of the present invention is to provide a stamper that can manufacture such an information recording medium.

  In order to achieve the above object, the information recording medium according to the present invention has a servo pattern formed by a concavo-convex pattern on at least one surface side of a substrate, and concentric or spiral data recording tracks are provided on the one surface side. The concave / convex pattern forming the data track pattern and constituting the servo pattern has a value obtained by dividing the unit convex portion length along the rotation direction of the base material by the distance from the center of the data track pattern from the inner peripheral side to the outer peripheral side. The unit convex portion length is defined to be smaller toward the side, and the value obtained by dividing the unit concave portion length along the rotation direction by the distance from the center of the data track pattern is from the inner peripheral side to the outer peripheral side. The unit recess length is defined so as to become smaller toward the center, and the distance from the center of the data track pattern is the same. The unit convex length and the unit concave length as the unit recess length along the rotating direction is a length equal to or less than the unit convex director along the rotational direction in the radial position is defined.

  Note that the “concentric or spiral data recording track” in the present specification has convex portions (unit recording elements) separated from both the radial direction and the rotational direction of the information recording medium by the concave portions of the concave-convex pattern. A track-shaped data recording unit in a data track pattern of a patterned medium arranged concentrically or spirally is included. The “unit convex portion length” in this specification refers to a reference length for detecting “one convex portion is present” when reading a magnetic signal from the information recording medium. Furthermore, the “unit recess length” in this specification refers to a reference length for detecting “one recess is present” when reading a magnetic signal from an information recording medium. Therefore, in an actual information recording medium, a servo pattern is formed by forming a convex portion that is an integral multiple of the unit convex portion length or a concave portion that is an integral multiple of the unit concave length according to the contents of the servo data. The In this case, the reference length for detecting “with one convex portion” and the reference length for detecting “with one concave portion” are defined as one common length in the entire servo pattern. Alternatively, the length may be defined to be different for each pattern according to the types of various patterns (preamble pattern, address pattern, burst pattern, etc.) constituting the servo pattern. In general, the formation part of the convex part is detected as “detection signal output” or “detection signal with high signal level”, and the formation part of the concave part is “no detection signal output” or “signal level”. Is detected as “Low detection signal”. Furthermore, in the present invention, even if a very slight manufacturing error occurs and the unit recess length in the concavo-convex pattern is slightly longer than the unit convex portion length, the unit recess length in the concavo-convex pattern is the unit. It shall be included in the category of length below the convex part length.

  Further, the information recording medium according to the present invention is configured such that the unit recess length is defined to be the same length or substantially the same length in the entire region from the inner circumference side to the outer circumference side, and constitutes the servo pattern. The uneven pattern is formed. In the present invention, even if a very slight manufacturing error occurs and the unit recess length in the uneven pattern slightly varies, those lengths are included in the category of equal lengths. And In addition, the “substantially equal length” in this specification includes a length within the allowable range of a slight width defined from the beginning separately from a manufacturing error, centering on a predetermined length as a manufacturing target. And

  Furthermore, the information recording medium according to the present invention is configured such that the unit convex portion length is defined to be equal to or substantially equal over the entire area from the inner circumference side to the outer circumference side, and constitutes the servo pattern. The uneven pattern is formed. In the present invention, even if a slight slight manufacturing error occurs and the unit convex portion length in the concave / convex pattern slightly varies, those lengths are included in the category of the equal length. And

  Further, the recording / reproducing apparatus according to the present invention provides the servo from the information recording medium based on any one of the above information recording media and read frequency information defined in advance according to the distance from the center of the data track pattern. And a control unit that reads out servo data associated with the pattern and performs servo control.

  Further, the recording / reproducing apparatus according to the present invention provides any one of the information recording media described above and a read frequency defined in advance for each of a plurality of annular regions concentrically divided from the inner peripheral side to the outer peripheral side. And a control unit that reads out servo data associated with the servo pattern from the information recording medium based on the information and performs servo control.

  The stamper according to the present invention is a stamper for manufacturing an information recording medium, and includes a convex portion formed corresponding to the concave portion of the concave / convex pattern in any one of the above information recording media, and the information recording medium. A concave / convex pattern having a concave portion formed corresponding to the convex portion of the concave / convex pattern is formed.

  According to the information recording medium and the recording / reproducing apparatus of the present invention, the unit convex portion length is defined so that the value obtained by dividing the unit convex portion length by the distance from the center of the data track pattern decreases from the inner peripheral side toward the outer peripheral side. In addition, the unit recess length is defined so that the value obtained by dividing the unit recess length by the distance from the center of the data track pattern decreases from the inner circumference side toward the outer circumference side, and the distance from the center of the data track pattern. The unit along the rotation direction is formed by forming the concave / convex pattern constituting the servo pattern by defining the unit convex part length and the unit concave part length so that the unit concave part length is equal to or shorter than the unit convex part length at the same radial position. The length of the recess is increased in proportion to the distance from the center of the data track pattern (the value obtained by dividing the unit recess length by the distance from the center is the outer periphery to the outer periphery. Compared to conventional information recording medium equal way) convex pattern over the entire region is formed up (magnetic disk 10x), the unit recess length of the outer peripheral side can be sufficiently shortened. Therefore, in the stamper for manufacturing this information recording medium, the length along the rotation direction of the convex portion corresponding to each concave portion of the information recording medium can be sufficiently shortened, so that a thick residue is removed during imprint processing. Without generating, each convex part of the stamper can be pushed into the resin layer sufficiently deeply. As a result, the thickness of the residue is substantially the same throughout the entire servo pattern formation region, so that it is possible to avoid a situation in which the recesses on the inner peripheral side of the servo pattern formation region excessively expand during the residue removal process. Therefore, it is possible to avoid a situation where each concave portion for the servo pattern finally formed in the concave portion portion of the resin layer is excessively expanded, and to form the concave / convex pattern for the servo pattern with high accuracy. Thereby, it is possible to provide an information recording medium having a servo pattern capable of reliably reading a magnetic signal in the entire area, and a recording / reproducing apparatus including the information recording medium.

  In this case, the unit recess length is defined such that the value obtained by dividing the unit recess length by the distance from the center of the data track pattern increases from the outer peripheral side toward the inner peripheral side. The situation where the manager becomes too short is avoided. Therefore, it is possible to avoid a situation in which the formation process of the recesses (development process for the resist layer, etching process for the magnetic layer, etc.) becomes difficult even when the information recording medium is manufactured by various manufacturing methods other than the imprint method. As a result, the concave portion can be formed with high accuracy in the entire servo pattern formation region. Further, by defining the unit convex portion length so that the value obtained by dividing the unit convex portion length by the distance from the center of the data track pattern becomes smaller from the inner peripheral side to the outer peripheral side, the unit convex portion length is specified. In the stamper, the length along the rotation direction of the concave portion corresponding to each convex portion of the information recording medium can be sufficiently shortened also on the outer peripheral side. Therefore, a sufficiently high convex portion can be formed in the resin layer (a sufficiently thick resin mask can be formed) by the resin material that is moved into the concave portion in the stamper by pressing the convex portion in the stamper during the imprint process. . Furthermore, the unit convex length and the unit concave length are defined so that the unit concave length along the rotation direction is equal to or shorter than the unit convex length along the rotation direction at the same radial position where the distance from the center of the data track pattern is equal. By forming the servo pattern (concave / convex pattern), it is possible to sufficiently shorten the unit concave portion length as compared with the concave / convex pattern formed so that the unit concave portion length exceeds the unit convex portion length. Therefore, in the stamper for manufacturing this information recording medium, the length along the rotation direction of each convex portion corresponding to each concave portion of the information recording medium can be sufficiently shortened, so that a thick residue is generated. The concavo-convex pattern can be transferred to the resin layer. As a result, it is possible to reliably avoid a situation where each concave portion of the resin layer expands excessively when the residue is removed, and to form the servo pattern with high accuracy.

  Further, according to the information recording medium and the recording / reproducing apparatus of the present invention, the servo pattern is defined so that the unit recess length is equal to or substantially equal over the entire area from the inner circumference side to the outer circumference side. By forming the concavo-convex pattern to constitute, in the stamper for manufacturing this information recording medium, the length along the rotation direction of each convex portion corresponding to each concave portion of the information recording medium is changed from the inner peripheral side to the outer peripheral side. The entire length can be equal. Therefore, the thickness of the residue generated at the time of manufacturing the information recording medium can be made uniform over the entire region from the inner peripheral side to the outer peripheral side. Thereby, a servo pattern (unevenness pattern) can be formed with higher accuracy from the inner circumference side to the outer circumference side. Also, when the information recording medium is manufactured by various manufacturing methods other than the imprint method by defining the unit recess length to be equal length or almost equal length in the entire region from the inner peripheral side to the outer peripheral side. As a result of forming the recesses easily (development process for the resist layer, etching process for the magnetic layer, etc.), the recesses can be formed with high accuracy in the entire servo pattern formation region.

  Further, according to the information recording medium and the recording / reproducing apparatus of the present invention, the servo pattern is defined so that the unit convex portion length is equal to or substantially equal over the entire area from the inner circumference side to the outer circumference side. By forming the concavo-convex pattern, the length along the rotation direction of each concave portion corresponding to each convex portion of the information recording medium in the stamper for manufacturing this information recording medium is uniform from the inner peripheral side to the outer peripheral side. The height of the convex part (resin material that functions as a mask) formed by the resin material moved into each concave part by pressing the convex part in the stamper during imprint processing It can be made uniform from the side to the outer peripheral side. As a result, the concave portion for the servo pattern can be formed with high accuracy using a mask having a uniform thickness (a convex portion having a uniform height).

  Further, according to the recording / reproducing apparatus of the present invention, the control unit associates the servo pattern with the servo pattern from the information recording medium based on the read frequency information defined in advance according to the distance from the center of the data track pattern. By reading the data, the servo pattern (servo data) can be reliably read while rotating the information recording medium under a constant angular velocity.

  Further, according to the recording / reproducing apparatus of the present invention, the control unit is configured to use the information recording medium based on the read frequency information defined in advance for each of the plurality of annular regions that are concentrically divided from the inner peripheral side to the outer peripheral side. By reading the servo data associated with the servo pattern from the number, the frequency types of the read frequency information can be reduced. For example, the frequency switching process of the read frequency information when the magnetic head seeks in the inner and outer peripheral directions. The number of times can be reduced. As a result, the seek operation can be executed in a short time, so that high-speed data access can be performed.

  Further, according to the stamper according to the present invention, a convex portion formed corresponding to the concave portion of the concave-convex pattern in any of the above information recording media, and a concave portion formed corresponding to the convex portion of the concave-convex pattern in the information recording medium As a result of the formation of the concavo-convex pattern, there is no excessively long convex portion along the rotation direction in the stamper. Therefore, during the imprint process for forming the concavo-convex pattern (intermediate for manufacturing information recording media) During the process of transferring the concave / convex pattern of the stamper to the resin layer in the body, the concave / convex pattern (each convex portion) of the stamper can be smoothly pushed into the resin layer. Therefore, it is possible to avoid a situation in which an inconvenience (a situation in which each concave portion is excessively expanded due to the occurrence of a thick residue on the intermediate body) due to an insufficient pushing amount of each convex portion. Thereby, an information recording medium capable of reliably reading servo data can be manufactured. Also, since there is no recess in the stamper that is excessively long along the rotation direction, the protrusion is sufficiently high by the resin material that is moved into the recess of the stamper by pressing the protrusion of this stamper during the imprint process. Can be formed on the resin layer (a sufficiently thick resin mask can be formed).

  Hereinafter, the best mode of an information recording medium, a recording / reproducing apparatus, and a stamper according to the present invention will be described with reference to the accompanying drawings.

A hard disk drive 1 shown in FIG. 1 is a magnetic recording / reproducing apparatus as an example of a recording / reproducing apparatus according to the present invention, and includes a spindle motor 2, a magnetic head 3, a signal conversion unit 4, a detection clock output unit 5, servo data. A detection unit 6, a driver 7, a control unit 8, a ROM 9, and a magnetic disk 10 are provided. In this case, as an example, the magnetic disk 10 is a discrete track type magnetic disk (patterned medium) capable of recording recording data by a perpendicular recording method, and corresponds to the information recording medium in the present invention. Specifically, as shown in FIG. 2, in the magnetic disk 10, a soft magnetic layer 12, an intermediate layer 13, and a magnetic layer 14 are formed on a glass substrate 11 in this order. In this case, the magnetic layer 14 formed on the intermediate layer 13 forms a predetermined concavo-convex pattern 20 by alternately forming the convex portions 21, 21,... And the concave portions 22 made of a magnetic material. To do. In addition, a nonmagnetic material 15 such as SiO ₂ is embedded in the recesses 22, 22. Further, a diamond-like carbon (DLC) thin film is formed on the nonmagnetic material 15 embedded in the concave portion 22 and the convex portion 21 by a CVD method as an example, and a protective layer (DLC film) having a thickness of about 2 nm. ) 16 is formed. In the magnetic disk 10, a lubricant (for example, a fluorine-based lubricant) is applied to the surface of the protective layer 16.

  The glass substrate 11 corresponds to the substrate in the present invention, and is formed such that a glass plate having a diameter of 2.5 inches is subjected to surface polishing to a thickness of about 0.6 mm. In addition, the base material in this invention is not limited to glass material, It can form with various nonmagnetic materials, such as aluminum and a ceramic. The soft magnetic layer 12 is formed to have a thickness of about 100 nm to 200 nm by sputtering a soft magnetic material such as a CoZrNb alloy. The intermediate layer 13 is a layer that functions as an underlayer for forming the magnetic layer 14, and is formed to have a thickness of about 40 nm by sputtering an intermediate layer forming material such as Cr or a CoCr nonmagnetic alloy. Has been. The magnetic layer 14 is a layer composed of convex portions 21, 21,... Made of a magnetic material. For example, a process of sputtering a CoCrPt alloy and an etching process using a resist pattern or the like as a mask to form the concave portion 22. , 22... Are executed in this order to form the convex portions 21, 21... (Concave pattern 20).

  In this case, as shown in FIG. 3, in the magnetic disk 10, servo pattern areas As, As,... Are provided between the track pattern areas At, At,. The discs 10 are defined so as to be alternately arranged in the rotation direction (direction of arrow R). As shown in FIGS. 4 and 5, the track pattern region At (inner track side track pattern region Ati and outer track side track pattern region Ato) has an uneven pattern 20t as a data track pattern. In this case, the concavo-convex pattern 20t has a large number of concentric convex portions 21t, 21t... (Data recording track: hereinafter also referred to as “recording track”) centered on the rotation center of the magnetic disk 10 (see FIG. 3) And concave portions 22t, 22t,... Between the convex portions 21t, 21t,. Although it is preferable that the rotation center of the magnetic disk 10 and the center O of the concave / convex pattern 20t coincide with each other, in reality, a very small deviation of about 30 to 50 μm may occur due to a manufacturing error. However, since the tracking servo control with respect to the magnetic head 3 is sufficiently possible with this amount of deviation, it can be said that the center of rotation and the center O are substantially the same. Further, the nonmagnetic material 15 is embedded in the concave portions 22t, 22t,... Of the concave / convex pattern 20t so that the surface of the track pattern region At is flattened.

  As shown in FIGS. 4 and 5, the servo pattern area As (inner circumference servo pattern area Asi and outer circumference servo pattern area Aso) is provided with an uneven pattern 20s as a servo pattern. In this case, the concavo-convex pattern 20s includes convex portions 21s, 21s... (Convex portions 21si and convex portions 21so) and concave portions 22s, 22s... (Concave portions 22si) constituting various servo patterns such as a preamble pattern, an address pattern, and a burst pattern. And a recess 22so). Further, in this magnetic disk 10, the length of the recess 22s along the rotation direction (the direction of the arrow R in each figure) is not proportional to the distance from the center O of the uneven pattern 20t (without increasing the length toward the outer peripheral side). ) The value obtained by dividing the unit recess length by the distance from the center of the data track pattern is made smaller as it goes from the inner circumference side to the outer circumference side so as to be equal throughout the entire area from the inner circumference side to the outer circumference side of the magnetic disk 10. An example is an example in which the “unit recess length is equal or approximately equal length” in the present invention) Each recess 22s, 22s... Is formed.

  Similarly, the length of the convex portion 21s along the rotation direction is also not proportional to the distance from the center O of the concave / convex pattern 20t (not as long as the outer peripheral side), but from the inner peripheral side to the outer peripheral side. This is an example in which the value obtained by dividing the unit convex portion length by the distance from the center of the data track pattern is defined to be smaller as it goes from the inner peripheral side to the outer peripheral side. An example defined to be “length or substantially equal length”) Each convex portion 21s, 21s... Is formed. Therefore, in this magnetic disk 10, the total length of the length of the convex portion 21s and the length of the concave portion 22s along the rotation direction (that is, the formation pitch of the convex portion 21s and the concave portion 22s) is from the center O of the concave-convex pattern 20t. It is defined to be equal in the entire area from the inner circumference side to the outer circumference side of the magnetic disk 10 without being proportional to the distance (not as long as the outer circumference side). Therefore, the concave / convex pattern 20s is formed so that the ratio of the length of the concave portion 22s to the length of the convex portion 21s along the rotation direction is the same in the entire region from the inner peripheral side to the outer peripheral side.

  Specifically, as shown in FIG. 4, in the inner peripheral side region Ai (for example, the formation region of the preamble pattern at a portion having a distance of 11 mm from the center O of the concave / convex pattern 20 t), the length L1i of the convex portion 21si. The length L3i, which is the total length of (as an example, 220 nm) and the length L2i of the recess 22si (as an example, 220 nm), is defined to be 440 nm. In addition, as shown in FIG. 5, the length L1o of the convex portion 21so (as an example) also in the outer peripheral side region Ao (as an example, the formation region of the preamble pattern at a portion whose distance from the center O of the uneven pattern 20t is 32 mm). The length L3o, which is the total length of the length L2o of the concave portion 22so (as an example, 220 nm equal to the length L2i of the concave portion 22si), is 440 nm. As a result, as shown in FIGS. 4 and 5, in this magnetic disk 10, the ratio of the length L2i of the concave portion 22si to the length L1i of the convex portion 21si of the concave / convex pattern 20s in the inner peripheral side region Ai and the outer peripheral side region Ao. The ratio of the length L2o of the concave portion 22so to the length L1o of the convex portion 21so at 1 is 1 (the unit concave portion length along the rotation direction is rotated at the same radial position where the distance from the center of the data track pattern is equal). An example of a state in which the unit convex portion length and the unit concave portion length are defined so as to be equal to or shorter than the unit convex portion length along the direction).

  In this case, regarding the ratio of the length of the concave portion 22s (unit concave portion length) to the length of the convex portion 21s (unit convex portion length), not only the preamble pattern but also the concave / convex pattern 20s constituting the address pattern and burst pattern. Are also defined in the same way. As for the burst pattern, the ratio of the unit concave portion length to the unit convex portion length in a region where a plurality of rectangular concave portions 22s, 22s,... It is defined to satisfy the above conditions. 4 and 5 schematically show a preamble pattern and a burst pattern in the servo pattern, and for easy understanding, the convex portions 21s, 21s,. The length of 22 s... Is shown only by the unit convex part length and unit concave part length of the servo pattern. Therefore, in the actual magnetic disk 10, the number of the convex portions 21s, 21s,... And the concave positions 22s, 22s,. Corresponding to various control data including information (pattern) such as sector address, the number, the forming position and the length of the convex portions 21s and the concave portions 22s are defined to form the concave / convex pattern 20s. In this case, the actual length of the convex portion 21s and the concave portion 22s is an integral multiple of the length of the convex portion 21s and the concave portion 22s (unit convex portion length and unit concave portion length).

  On the other hand, the spindle motor 2 rotates the magnetic disk 10 at a constant speed of 4200 rpm as an example under the control of the control unit 8. As shown in FIG. 1, the magnetic head 3 is attached to an actuator 3b via a swing arm 3a, and is moved on the magnetic disk 10 during recording / reproduction of recorded data on the magnetic disk 10. The magnetic head 3 also reads servo data from the servo pattern area As of the magnetic disk 10, magnetically writes recording data to the track pattern area At (convex portions 21t, 21t,...), And the track pattern area At. The recording data that is magnetically written to the disk is read out. The magnetic head 3 is actually formed on the bottom surface (air bearing surface) of the slider for floating the magnetic head 3 with respect to the magnetic disk 10, but the description and illustration of the slider are omitted. The actuator 3 b moves the magnetic head 3 to an arbitrary recording / reproducing position on the magnetic disk 10 by swinging the swing arm 3 a with the drive current supplied from the driver 7 under the control of the control unit 8. The signal conversion unit 4 includes an amplifier, an LPF (Low Pass Filter), an A / D converter and the like (not shown), and amplifies various signals acquired from the magnetic disk 10 by the magnetic head 3 to remove noise. After A / D conversion, output.

  The ROM 9 stores clock data Dcl regarding the read frequency information to be output by the control unit 8 in association with the movement position (distance from the center O) of the magnetic head 3. In this case, as will be described later, the control unit 8 sets the frequency of the read frequency information so that the wavelength becomes shorter toward the outer peripheral side in proportion to the distance from the center O of the concave / convex pattern 20t, as an example, based on the clock data Dcl. The output is changed linearly and output to the detection clock output unit 5. The detection clock output unit 5 acquires read frequency information output from the control unit 8 based on the clock data Dcl, and from the digital data output from the signal conversion unit 4 via the magnetic head 3, the servo pattern. Preamble data (signal) read from the area As is acquired (detected). The detection clock output unit 5 adjusts the phase, frequency, etc. based on the acquired read frequency information and preamble data, thereby generating a detection clock Cls used when detecting actual servo data. And output to the servo data detector 6.

  In this case, in this magnetic disk 10, the concave / convex pattern 20 s is formed so that the length of the servo pattern region As along the rotation direction is the same in the entire region from the inner peripheral side to the outer peripheral side. When rotating at a constant speed at a constant angular velocity, the time during which the servo pattern region As passes below the magnetic head 3 is shorter on the outer peripheral side. Therefore, as an example, in the state where the magnetic disk 10 is rotated at a constant speed of 4200 rpm, the control unit 8 causes the magnetic head 3 to be on-track on the recording track (convex portion 21t) in the inner peripheral area Ai. Sometimes, read frequency information of 22 MHz is output, and when the magnetic head 3 is on-tracked to the recording track (convex portion 21t) in the outer peripheral area Ao, read frequency information of 64 MHz is output. When the magnetic head 3 is on-tracked to any recording track (convex portion 21t) between the inner peripheral area Ai and the outer peripheral area Ao, the controller 8 sets the frequency of the read frequency information to 22 MHz. The output is varied linearly in proportion to the distance from the center O of the concave / convex pattern 20t between ˜64 MHz.

  The servo data detection unit 6 acquires (detects) servo data Ds from the digital data output from the signal conversion unit 4 by reading in synchronization with the detection clock Cls output from the detection clock output unit 5. Output to the control unit 8. The driver 7 controls the actuator 3b in accordance with a control signal from the control unit 8 to turn the magnetic head 3 on the desired recording track (convex portion 21t). The control unit 8 comprehensively controls the hard disk drive 1. Further, the control unit 8 on-tracks the recording head on the magnetic disk 10 from the inner circumference side to the outer circumference side based on the head position information output from the servo data detection unit 6. And the clock data Dcl (frequency change condition) preliminarily defined according to the position of the magnetic head 3 (the position of the recording track to which the magnetic head 3 is to be moved) and stored in the ROM 9. As described above, the frequency of the read frequency information is changed according to the data) and output to the detection clock output unit 5. Further, the control unit 8 controls the driver 7 based on the servo data Ds output from the servo data detection unit 6.

  Next, a method for manufacturing the magnetic disk 10 will be described.

  In manufacturing the magnetic disk 10, the intermediate body 30 shown in FIG. 6 and the stamper 35 shown in FIG. 7 are used. In this case, as shown in FIG. 6, the intermediate 30 includes a soft magnetic layer 12, an intermediate layer 13, and a magnetic layer 14 formed in this order on the glass substrate 11, and on the magnetic layer 14. The mask layer 17 and a resin layer (resist layer) 18 having a thickness of about 80 nm are formed. On the other hand, the stamper 35 is an example of a stamper for manufacturing an information recording medium according to the present invention. As shown in FIG. 7, the stamper 35 has a concavo-convex positional relationship with the concavo-convex pattern 20 (the concavo-convex patterns 20t, 20s). An inverted concavo-convex pattern 39 is formed so that the magnetic disk 10 can be manufactured by the imprint method. In this case, the concave / convex pattern 39 of the stamper 35 corresponds to the concave portions 22, 22... In the concave / convex pattern 20 of the magnetic disk 10, and the concave portions 39 b, 39 b. It is formed corresponding to 21, 21,. Therefore, in this stamper 35, the length along the rotational direction of the convex portion 39a is substantially equal to the length along the rotational direction of the concave portion 22 in the concave / convex pattern 20, and the length along the rotational direction of the concave portion 39b is equal to the concave / convex pattern. 20 is substantially equal to the length along the rotation direction of the convex portion 21. In addition, it does not specifically limit about the manufacturing method of the intermediate body 30 and the stamper 35, It can manufacture by well-known various manufacturing methods.

  In manufacturing the magnetic disk 10 using the intermediate 30 and the stamper 35, as shown in FIG. 8, first, the uneven pattern 39 of the stamper 35 is transferred to the resin layer 18 of the intermediate 30 by the imprint method. Specifically, the projections 39 a, 39 a... Of the concavo-convex pattern 39 are pressed into the resin layer 18 of the intermediate body 30 by pressing the formation surface of the concavo-convex pattern 39 on the stamper 35 against the resin layer 18 of the intermediate body 30. In this case, the magnetic disk 10 manufactured using this stamper 35 has a value obtained by dividing the length of the convex portions 21s, 21s... (Unit convex portion length) by the distance from the center O of the concave-convex pattern 20t, as described above. The lengths of the convex portions 21s, 21s,... Are defined so as to decrease from the inner peripheral servo pattern region Asi toward the outer peripheral servo pattern region Aso, and the lengths of the concave portions 22s, 22s,. The lengths of the recesses 22s, 22s,... Are reduced so that the value obtained by dividing the recess length by the distance from the center O of the recess / protrusion pattern 20t decreases toward the outer periphery servo pattern region Aso from the inner periphery servo pattern region Asi. It is prescribed.

  Specifically, in the magnetic disk 10 manufactured using the stamper 35, the length of the concave portion 22s (the concave portions 22si, 22so) is the length of the servo pattern region As from the inner peripheral servo pattern region Asi to the outer peripheral servo pattern region Aso. It is stipulated that the lengths are equal throughout. Therefore, the stamper 35 for manufacturing the magnetic disk 10 has a convex portion 39a whose length along the rotation direction greatly exceeds the lengths L2i and L2o in the entire area corresponding to the servo pattern area As on the magnetic disk 10. The recesses 39b, 39b,... Are formed so that the length of the projection 39a is substantially equal to the lengths L2i, L2o. As a result, the convex portions 39a, 39a,... Are smoothly pushed into the resin layer 18. Thus, the intermediate body 30 is sufficiently deep enough that the convex portions 39a, 39a,... Of the stamper 35 are not deeply formed between the tip of the convex portion 39a of the stamper 35 and the mask layer 17 of the intermediate body 30. Is pushed into the resin layer 18.

  At this time, the resin material at the portion into which the convex portions 39a, 39a,... Are pushed moves into the concave portions 39b, 39b,. Convex portions 41a, 41a,... Made of a resin material are formed. In this case, in the stamper 35, as described above, the lengths of the convex portions 39a, 39a,... Along the rotation direction are equal in the entire area corresponding to the servo pattern region As. Therefore, the amount of movement of the resin material that moves toward the recesses 39b, 39b,... By the pressing of the protrusions 39a, 39a,. Further, in the magnetic disk 10 manufactured using this stamper 35, the length of the convex portion 21s (the convex portions 21si, 21so) of the servo pattern region As from the inner peripheral servo pattern region Asi to the outer peripheral servo pattern region Aso. It is stipulated that the lengths are equal throughout. Therefore, the stamper 35 for manufacturing the magnetic disk 10 does not have the recess 39b whose length along the rotation direction greatly exceeds the lengths L1i and L1o in the entire region corresponding to the servo pattern area As on the magnetic disk 10. Thus, the convex portions 39a, 39a,... Are formed (so that the length of the concave portion 39b is substantially equal to the lengths L1i, L1o). As a result, the height of the resin material moved into the concave portion 39b, that is, the height of the convex portion 41a is uniform over the entire area corresponding to the servo pattern region As.

  Next, the stamper 35 is peeled off from the intermediate 30 and, further, the resin (residue: not shown) remaining on the bottom surface is removed by oxygen plasma treatment, so that the mask layer 17 in the intermediate 30 is shown in FIG. A concave / convex pattern 41 made of the resin layer 18 is formed thereon. In this case, as described above, the mask 30 is pushed almost uniformly into the resin layer 18 of the intermediate body 30 from the convex portions 39a, 39a,. Since the thickness of the residue on the layer 17 is substantially uniform over the entire region, when removal of the residue is completed at any part of the intermediate body 30 (for example, the inner peripheral region), another region (for example, the outer periphery) The removal of the residue is completed almost simultaneously in the side area). Next, etching is performed using the concave / convex pattern 41 (resin layer 18) from which the residue has been removed as a mask, so that the masks (convex portions 41 a, 41 a. Etching the exposed mask layer 17 from.

  In this case, the stamper 35 used to form the concavo-convex pattern 41 used as a mask has a concavo-convex positional relationship reversed with respect to the concavo-convex pattern 20 of the magnetic disk 10. The value obtained by dividing the length of the part (the length corresponding to the unit convex part length of the convex part 39a) by the distance from the center of the concave / convex pattern 39 (the position corresponding to the center O of the concave / convex pattern 20t) increases from the inner peripheral side toward the outer peripheral side. It is getting smaller. In other words, the concavo-convex pattern 39 of the stamper 35 increases as the value obtained by dividing the unit convex portion length by the distance from the center (position corresponding to the center O of the concavo-convex pattern 20t) increases from the outer peripheral side to the inner peripheral side. Therefore, in the concavo-convex pattern 41 formed by transferring the concavo-convex pattern 39, the unit concave portion length (the length corresponding to the unit concave portion length of the concave portion 41b) is the position corresponding to the center of the concave / convex pattern 41 (the center O of the concave / convex pattern 20t). The value divided by the distance from the outer peripheral side increases from the outer peripheral side toward the inner peripheral side, thereby avoiding a situation in which the length along the rotation direction of the concave portion 41b on the inner peripheral side becomes excessively short. Yes. Therefore, it is possible to reliably etch the mask layer 17 exposed from the sufficiently wide recess 41b without causing an etching failure due to the recess 41b being excessively narrow.

  In the stamper 35 used to form the concavo-convex pattern 41, the length of the convex portion 39a corresponding to the unit concave portion length in the magnetic disk 10 is the same length in the entire region from the inner peripheral side to the outer peripheral side. Therefore, in the concavo-convex pattern 41 formed by transferring the concavo-convex pattern 39, the unit concave portion length (the length corresponding to the unit concave portion length of the concave portion 41b) is the same length in the entire region from the inner peripheral side to the outer peripheral side. The mask layer 17 can be uniformly etched from the inner peripheral side to the outer peripheral side by using the uneven pattern 41 in which the removal of the residue is completed. Thereby, as shown in FIG. 10, the uneven | corrugated pattern 42 which has the convex part 42a and the recessed part 42b is formed in the mask layer 17 of the intermediate body 30. As shown in FIG.

  Next, by performing an etching process using the concave / convex pattern 42 (mask layer 17) as a mask, the bottom of the concave portions 42b, 42b,... In the concave / convex pattern 42 is exposed from the mask (the convex portions 42a, 42a,...). The magnetic layer 14 is etched. Accordingly, as shown in FIG. 11, the convex portion 21 whose length along the rotational direction is substantially equal to the length along the rotational direction of the concave portion 39 b in the stamper 35, and the length along the rotational direction thereof is the stamper 35. A concave / convex pattern 20 (concave / convex patterns 20t, 20s) having a concave portion 22 substantially equal to the length along the rotation direction of the convex portion 39a is formed on the magnetic layer 14 of the intermediate body 30. Next, the mask layer 17 remaining on the convex portions 21, 21,... Is selectively etched to completely remove the remaining mask layer 17, and the convex portions 21, 21.・ Expose the tip of the tip.

Next, SiO ₂ as the nonmagnetic material 15 is sputtered. At this time, the concave portions 22, 22,... Are completely filled with the nonmagnetic material 15, and a layer of the nonmagnetic material 15 having a thickness of, for example, about 60 nm is formed on the convex portions 21, 21,. Thus, the nonmagnetic material 15 is sufficiently sputtered. Subsequently, an ion beam etching process is performed on the layer of the nonmagnetic material 15 on the magnetic layer 14 (above the convex portions 21, 21,... And the concave portions 22, 22,...). At this time, the ion beam etching process is continued until the projecting end surfaces of the convex portions 21, 21,... Are exposed from the nonmagnetic material 15. Thereby, the surface of the intermediate 30 is planarized. Subsequently, after forming the protective layer 16 by depositing a diamond-like carbon (DLC) thin film by CVD so as to cover the surface of the intermediate 30, a fluorine-based lubricant is averaged on the surface of the protective layer 16. Application is performed so that the thickness is, for example, about 2 nm. Thereby, the magnetic disk 10 is completed as shown in FIG.

  In this magnetic disk 10, as described above, the lengths (lengths L1i, L1o) of the protrusions 21s, 21s,... Along the rotation direction in the uneven pattern 20s of the servo pattern area As and the respective directions along the rotation direction. The lengths (lengths L2i, L2o) of the recesses 22s, 22s,... Are equal over the entire area from the inner periphery side to the outer periphery side of the magnetic disk 10, and the respective protrusions 21s, 21s,. 22 s... Are formed. Therefore, in this magnetic disk 10, the total length (length L3i, L3o) of the length of the convex part 21s and the length of the concave part 22s along the rotation direction in the concave-convex pattern 20s of the servo pattern area As is the inner circumference of the magnetic disk 10. The convex portions 21s, 21s, and the concave portions 22s, 22s,... Are formed so as to be equal over the entire region from the side to the outer peripheral side. As a result, as shown in FIG. 3, the length L4i along the rotation direction of the inner servo pattern area Asi (uneven pattern 20s of the inner peripheral area Ai) and the outer servo pattern area Aso (outer peripheral area Ao). The length L4o along the rotation direction of the concave / convex pattern 20s) is equal. For this reason, in the magnetic disk 10, the length of the track pattern region At along the rotation direction is gradually increased from the inner peripheral side toward the outer peripheral side. Specifically, the outer circumferential side track pattern region Ato (the concave / convex pattern 20t of the outer peripheral side region Ao) is longer than the length L5i along the rotation direction of the inner peripheral side track pattern region Ati (the concave / convex pattern 20t of the inner peripheral side region Ai). ) In the direction of rotation L5o is longer. Therefore, as compared with the conventional magnetic disk 10x, the recordable capacity of the recording data is increased by the length of the convex portion 21t on the outer peripheral side.

  Further, in the magnetic disk 10, as described above, the length of the convex portions 21s, 21s,... Along the rotation direction in the concave / convex pattern 20s (servo pattern) and the concave portions 22s, 22s,. The convex portions 21s, 21s,... And the concave portions 22s, 22s,... Are formed so that the length is equal over the entire area from the inner circumference side to the outer circumference side of the magnetic disk 10. Therefore, in the hard disk drive 1 equipped with the magnetic disk 10, the controller 8 controls the position of the magnetic head 3 (the center O of the concave / convex pattern 20t) based on the signal from the servo data detector 6 at the time of recording / reproducing recorded data. Servo data Ds is read by specifying the frequency of the read frequency information linearly according to the position where the magnetic head 3 is to be moved and outputting it to the detection clock output unit 5. The frequency of the clock used as a reference is changed. Thus, it is possible to reliably read (detect) the servo data Ds from the entire servo pattern area As from the inner circumference servo pattern area Asi to the outer circumference servo pattern area Aso. In addition, the control unit 8 controls the driver 7 based on the servo data Ds read from the servo pattern area As, thereby driving the actuator 3b to turn the magnetic head 3 on a desired track. As a result, recording / reproduction of recording data is performed via the magnetic head 3 that is on-tracked to the convex portions 21t, 21t... (Data recording track) in the track pattern area At.

  Thus, according to the magnetic disk 10 and the hard disk drive 1, the unit convex portion length is such that the value obtained by dividing the unit convex portion length by the distance from the center O of the concave / convex pattern 20t decreases from the inner peripheral side toward the outer peripheral side. And the unit recess length is defined such that the value obtained by dividing the unit recess length by the distance from the center O of the concavo-convex pattern 20t decreases from the inner peripheral side toward the outer peripheral side, and the center O of the concavo-convex pattern 20t. By forming the concave / convex pattern 20s (servo pattern) by defining the unit convex portion length and the unit concave portion length so that the unit concave portion length is equal to or shorter than the unit convex portion length at the same radial position at the same distance from So that the unit concave length along the length increases in proportion to the distance from the center (the value obtained by dividing the unit convex length by the distance from the center is the entire area from the inner circumference side to the outer circumference side. Over to equal to) than the conventional magnetic disk 10x which uneven pattern is formed, the unit recess length of the outer peripheral side can be sufficiently shortened. Therefore, in the stamper 35 for manufacturing the magnetic disk 10, the length along the rotation direction of the convex portions 39a, 39a,... Corresponding to the concave portions 22s, 22s,. Therefore, at the time of imprint processing, the convex portions 39a, 39a,... Of the stamper 35 are sufficiently formed without causing a thick residue between the tip portion of the convex portion 39a in the stamper 35 and the mask layer 17 of the intermediate 30. Can be pushed deeply into the resin layer 18 of the intermediate 30. As a result, the thickness of the residue is almost the same throughout the servo pattern region As, and therefore, the situation where the recesses 41b, 41b,... In the inner peripheral servo pattern region Asi are excessively expanded during the removal process of the residue is avoided. . Therefore, it is possible to avoid the situation where the recesses 22si, 22si,... Finally formed in the recesses 41b, 41b,. Thereby, it is possible to provide the magnetic disk 10 having the servo pattern capable of reliably reading the magnetic signal in the entire servo pattern area As, and the hard disk drive 1 including the magnetic disk 10.

  In this case, since the unit recess length is defined such that the value obtained by dividing the unit recess length by the distance from the center O of the concavo-convex pattern 20t increases from the outer peripheral side toward the inner peripheral side, A situation in which the length of the concave portion becomes excessively short is avoided. Therefore, it is possible to avoid a situation in which the formation process of the recesses (etching process for the mask layer 17 and the magnetic layer 14 and the like) at the time of manufacture becomes difficult. As a result, the recesses 22s, 22s,. It can be formed with accuracy. In order to manufacture the magnetic disk 10, the unit convex portion length is defined so that the value obtained by dividing the unit convex portion length by the distance from the center O of the concave / convex pattern 20t decreases from the inner peripheral side toward the outer peripheral side. In the stamper 35, the length along the rotation direction of the concave portions 39b, 39b,... Corresponding to the convex portions 21s, 21s,. For this reason, sufficiently high convex portions 41a, 41a,... Are formed on the resin layer 18 by the resin material that is moved into the concave portions 39b, 39b,... By pressing the convex portions 39a, 39a,. It is possible to form (a sufficiently thick resin mask is formed). Further, the unit convex portion length and the unit concave portion length are defined so that the unit concave portion length along the rotational direction is equal to or shorter than the unit convex portion length along the rotational direction at the same radial position where the distance from the center O of the concave / convex pattern 20t is equal. By forming the concave / convex pattern 20s, the unit concave portion length can be sufficiently shortened as compared with the concave / convex pattern formed so that the unit concave portion length exceeds the unit convex portion length. Therefore, the length along the rotation direction of the convex portions 39a, 39a,... Corresponding to the concave portions 22s, 22s,... Of the magnetic disk 10 in the stamper 35 can be sufficiently shortened. The concavo-convex pattern 41 can be formed without causing any residue. As a result, it is possible to reliably avoid the situation where the concave portions 41b, 41b,...

  Further, according to the magnetic disk 10 and the hard disk drive 1, the concave / convex pattern 20s (servo pattern) is formed by defining the unit concave portion length to be equal in the entire area from the inner peripheral side to the outer peripheral side. In the stamper 35 for manufacturing the magnetic disk 10, the lengths of the convex portions 39a, 39a,... Corresponding to the concave portions 22s, 22s,. The entire length can be equal. Therefore, the thickness of the residue generated when the magnetic disk 10 is manufactured can be made uniform over the entire area from the inner peripheral side to the outer peripheral side. Accordingly, the concave / convex pattern 20s can be formed with higher accuracy from the inner peripheral servo pattern region Asi to the outer peripheral servo pattern region Aso. Further, by defining the unit recess length to be the same length or almost the same length in the entire region from the inner periphery side to the outer periphery side, a recess formation process during manufacturing (etching process for the mask layer 17 and the magnetic layer 14) As a result, the recesses 22s, 22s,... Can be formed with high accuracy over the entire servo pattern region As.

  Furthermore, according to the magnetic disk 10 and the hard disk drive 1, the concave / convex pattern 20s (servo pattern) is formed by defining the unit convex portion length to be equal throughout the entire area from the inner peripheral side to the outer peripheral side. In the stamper 35 for manufacturing the magnetic disk 10, the lengths along the rotation direction of the concave portions 39b, 39b,... Corresponding to the convex portions 21s, 21s,. Therefore, during the imprint process, the height of the convex portion 41a (resin material functioning as a mask) formed by the resin material moved into the concave portion 39b by the pressing of the convex portion 39a in the stamper 35 is set. It can be made uniform from the inner circumference side to the outer circumference side. As a result, the concave portions 22s, 22s,... Can be formed with high accuracy using a mask having a uniform thickness (the convex portion 41a having a uniform height).

  Further, according to the hard disk drive 1, the servo data detection unit 6 is associated with the servo pattern from the magnetic disk 10 based on the read frequency information defined in advance according to the distance from the center O of the uneven pattern 20t. By reading the servo data Ds, it is possible to reliably read the servo data Ds from the servo pattern area As while rotating the magnetic disk 10 under a constant angular velocity.

  Further, according to the stamper 35 for manufacturing the magnetic disk 10, the convex portions 39a, 39a formed corresponding to the concave portions 22, 22,... Of the concave / convex pattern 20 (the concave / convex patterns 20t, 20s) in the magnetic disk 10 are provided. ··· and the concave / convex pattern 39 having the concave portions 39b, 39b ·· formed corresponding to the convex portions 21, 21 ·· of the concave / convex pattern 20 in the magnetic disk 10, the length along the rotation direction is increased. Since the excessively long convex portion 39a does not exist in the stamper 35, the concave / convex pattern 39 (the convex portions 39a, 39a,...) Of the stamper 35 is smoothly applied to the resin layer 18 of the intermediate 30 during the imprint process. Can be pushed in. Therefore, inconvenience due to insufficient pushing amount of the convex portions 39a, 39a,... (A situation where the concave portions 41b, 41b,... Excessively expand due to the occurrence of thick residues on the mask layer 17) occurs. The situation can be avoided. As a result, the magnetic disk 10 capable of reliably reading the servo data Ds can be manufactured. Further, since the concave portion 39b having an excessively long length in the rotational direction does not exist in the stamper 35, the resin material that is moved into the concave portions 39b, 39b,... By pressing the convex portions 39a, 39a,. Thus, sufficiently high convex portions 41a, 41a,... Can be formed in the resin layer 18 (a sufficiently thick resin mask is formed).

  In addition, this invention is not limited to said structure. For example, the lengths (lengths L1i, L1o) of the convex portions 21s, 21s,... Along the rotation direction in the entire servo pattern region As (from the inner peripheral servo pattern region Asi to the outer peripheral servo pattern region Aso) and Although the example in which the concave / convex pattern 20s is formed so that the lengths (lengths L2i, L2o) of the concave portions 22s, 22s,... Are equal to each other, the length of the convex portions 21s, 21s,. The concavo-convex pattern 20s may be formed so that the lengths of the portions from the inner peripheral side to the outer peripheral side are slightly different. Specifically, the convex portion 21so on the outer peripheral side is slightly longer in the rotational direction than the convex portion 21si on the inner peripheral side, or the outer peripheral side than the concave portion 22si on the inner peripheral side. It is possible to adopt a configuration in which the concave portion 22so of the concave portion 22so is slightly longer in the rotational direction. In addition, the outer convex portion 21so has a slightly shorter length along the rotation direction than the inner peripheral convex portion 21si, or the outer peripheral concave portion 22so has an inner peripheral concave portion 22si. It is also possible to adopt a configuration in which the length along the rotational direction is slightly shorter.

  Even if the lengths of the recesses 22s, 22s,... Are different as described above, the length of the recess 22so on the outer peripheral side is made shorter than the length L2xo of the recess 22sxo in the conventional magnetic disk 10x. By defining the unit recess length, the length of the corresponding protrusion in the stamper for manufacturing the magnetic disk can be sufficiently shortened even on the outer peripheral side. Therefore, a situation in which a thick residue is generated during imprinting can be sufficiently avoided. Further, even if the lengths of the convex portions 21s, 21s,... Are different as described above, the length of the convex portion 21so on the outer peripheral side is set to the length L1xo of the convex portion 21sxo in the conventional magnetic disk 10x. By defining the length of the unit convex portion to be shorter than that, the length of the corresponding concave portion in the stamper for manufacturing the magnetic disk can be sufficiently shortened also on the outer peripheral side. Therefore, sufficiently high convex portions 41a, 41a,... Are formed on the resin layer 18 by a resin material that is moved into the concave portions 39b, 39b,... By pressing the convex portions 39a, 39a,. A thick resin mask can be formed).

  In the hard disk drive 1 described above, the control unit 8 specifies the position of the magnetic head 3 (distance from the center O of the concave / convex pattern 20t) based on the signal from the servo data detection unit 6, and the magnetic head 3 Although a configuration is adopted in which the frequency of the read frequency information is linearly changed according to the position to be moved and output to the detection clock output unit 5, the present invention is not limited to this. For example, as shown in FIG. 12, the area from the inner peripheral area Ai to the outer peripheral area Ao of the magnetic disk 10 is concentrically divided into a plurality of annular areas A1, A2,... AN (N is a natural number of 2 or more) In the following, when not distinguished, “annular area AM (M is also a natural number of 2 or more and N or less)” is defined, and the frequency of the read frequency information is previously defined for each annular area AM. Further, at the time of recording / reproducing, the control unit 8 specifies the position of the magnetic head 3 (annular area AM) based on the signal from the servo data detection unit 6 and also moves the magnetic head 3 at a position (annular area). (AM) is output to the detection clock output unit 5.

  In this case, the width (length along the radial direction of the magnetic disk 10) of each of the annular regions A1, A2,... AN is a range in which the servo data Ds can be read based on the read frequency information of the same frequency. That is, the detection clock output unit 5 adjusts the phase and frequency based on the read frequency information and the preamble data, and generates the detection clock Cls used as a synchronization clock for actually reading the servo data. It is preferable to define within the possible range. According to this configuration, compared with the hard disk drive 1 described above, the control unit 8 linearly changes the frequency of the read frequency information according to the distance of the magnetic head 3 from the center O of the uneven pattern 20t. Since the number of types of read frequency information is small, for example, the number of frequency switching processes of read frequency information when the magnetic head 3 performs a seek operation in the inner and outer peripheral directions can be reduced. As a result, the seek operation can be executed in a short time, so that high-speed data access can be performed.

  Further, in the hard disk drive 1 described above, the control unit 8 rotates the magnetic disk 10 at a constant angular speed and the detection clock output unit according to the distance of the magnetic head 3 from the center O of the concave / convex pattern 20t. However, the present invention is not limited to this, and the magnetic disk 10 is rotated at a constant linear velocity, and the constant frequency is read from the controller 8. A configuration in which the servo data detector 6 reads the servo data Ds by outputting information can be employed. In addition, the servo pattern in the present invention is not limited to the above example, and the unit convex portion length and unit so as to invert the concavo-convex shape of the concavo-convex pattern 20s in the servo pattern area As of the magnetic disk 10 and satisfy the various conditions in the present invention. The servo pattern can also be formed by defining the recess length. Further, in the magnetic disk 10 described above, the protrusions 21, 21... In the concavo-convex pattern 20 are formed of a magnetic material from the base end portion to the protruding end portion, but the present invention is not limited to this, and FIG. The magnetic layer 14a is formed so as to cover the concavo-convex pattern formed on the substrate 11a as in the magnetic disk 10a shown in FIG. The concave / convex pattern 20a can be constituted by the concave portions 22a, 22a,... Formed by the magnetic layer 14a.

  In this case, the concave / convex pattern of the base material 11a is the same as the method for forming the concave / convex pattern 20 in the magnetic disk 10 described above, and the base material 11a is formed using the concave / convex pattern 42 used as a mask when etching the magnetic layer 14, for example. It can be formed by etching. Further, for example, the uneven pattern can be formed on the substrate 11a by press molding or injection molding using the stamper 35. As described above, even when the uneven pattern is formed by various manufacturing methods other than the imprint method, the uneven pattern 20s can be formed with high accuracy. Further, as in the magnetic disk 10b shown in FIG. 14, the magnetic layer 14b constituting the convex portions 21, 21,... And the magnetic portions constituting the bottom surfaces of the concave portions 22b, 22b,. The concavo-convex pattern 20b can also be configured by continuing the layer 14b. In the magnetic disks 10, 10 a, and 10 b, the nonmagnetic material 15 is embedded in each concave portion 22 to flatten the surface. However, when sufficient floating stability of the magnetic head 3 can be obtained, the concave portion Therefore, the nonmagnetic material 15 corresponding to 22 can be eliminated. Further, the information recording medium according to the present invention includes not only a perpendicular recording type magnetic disk such as the magnetic disks 10, 10a and 10b but also a longitudinal recording type magnetic disk.

  Furthermore, although the method for manufacturing the magnetic disk 10 by the imprint method has been described above, the method for manufacturing the information recording medium according to the present invention is not limited to this. For example, a servo pattern and a data track pattern are drawn on the resin layer 18 of the intermediate 30 using an electron beam drawing apparatus, and development processing is performed, so that the concave / convex pattern having the concave / convex positional relationship with the aforementioned concave / convex pattern 41 is formed on the resin layer 18. An information recording medium similar to the magnetic disk 10 can be manufactured by forming and performing an etching process on the mask layer 17 using the uneven pattern as a mask. In this case, in the information recording medium according to the present invention, the value obtained by dividing the unit convex portion length by the distance from the center of the data track pattern is defined so as to decrease from the inner peripheral side toward the outer peripheral side, and the unit concave portion length. The value obtained by dividing by the distance from the center of the data track pattern is defined so as to decrease as it goes from the inner circumference side to the outer circumference side, thereby forming an uneven pattern constituting the servo pattern. In other words, in the information recording medium according to the present invention, both the value obtained by dividing the unit convex portion length by the distance from the center of the data track pattern and the value obtained by dividing the unit concave portion length by the distance from the center of the data track pattern A concavo-convex pattern is formed so as to increase from the side toward the inner peripheral side. Therefore, according to the information recording medium of the present invention, since the situation in which the unit convex portion length and the unit concave portion length become excessively short on the inner peripheral side is avoided, the concave portion forming process (development on the resist layer) during manufacturing is avoided. It is possible to avoid a situation in which it is difficult to perform processing and etching processing on the magnetic layer. In this case, even if the servo pattern or the like is further miniaturized in response to a request for high-density recording, the information recording medium according to the present invention allows the servo pattern to be accurately reproduced in the entire servo pattern area. Can be formed.

2 is a block diagram showing a configuration of a hard disk drive 1. FIG. 2 is a cross-sectional view showing a layer structure of a magnetic disk 10. FIG. 1 is a plan view of a magnetic disk 10. FIG. 2 is a plan view of an inner peripheral area Ai in the magnetic disk 10. FIG. 3 is a plan view of an outer peripheral side area Ao in the magnetic disk 10. FIG. 3 is a cross-sectional view of an intermediate body 30 for manufacturing the magnetic disk 10. FIG. 3 is a cross-sectional view of a stamper 35 for manufacturing the magnetic disk 10. FIG. FIG. 4 is a cross-sectional view of a state in which a concavo-convex pattern 39 of a stamper 35 is pressed against a resin layer 18 of an intermediate 30. FIG. 9 is a cross-sectional view of a state in which the stamper 35 is peeled from the resin layer 18 in the state shown in FIG. 8 to form an uneven pattern 41 (resin mask) on the mask layer 17. FIG. 6 is a cross-sectional view of a state in which an uneven pattern 42 (mask) is formed on the magnetic layer 14 by etching the mask layer 17 using the uneven pattern 41 as a mask. FIG. 4 is a cross-sectional view of a state in which an uneven pattern 20 is formed on the intermediate layer 13 by etching the magnetic layer 14 using the uneven pattern 42 as a mask. It is a top view which shows an example of cyclic | annular area | region A1, A2, ... AN. It is sectional drawing which shows the layer structure of the magnetic disc 10a. It is sectional drawing which shows the layer structure of the magnetic disc 10b. It is a top view of the conventional magnetic disk 10x. FIG. 6 is a plan view of an inner peripheral area Axi in the magnetic disk 10x. It is a top view of outer peripheral side area | region Axo in the magnetic disc 10x. FIG. 11 is a cross-sectional view of the resin layer in a state where the convex portions 39ax, 39ax,... (The convex portions 39ax, 39ax,... Having a short length along the rotation direction) of the stamper are pushed in the manufacturing process of the magnetic disk 10x. FIG. 11 is a cross-sectional view of a resin layer in a state in which the convex portions 39ax, 39ax,... (The convex portions 39ax, 39ax,... Having a long length along the rotation direction) of the stamper are pushed in the manufacturing process of the magnetic disk 10x.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hard disk drive 5 Detection clock output part 6 Servo data detection part 7 Driver 10, 10a, 10b Magnetic disk 11 Glass base material 11a Base material 14, 14a, 14b Magnetic layer 18 Resin layer 20, 20a, 20b, 20s, 20t Concavity and convexity Pattern 21, 21a, 21b, 21s, 21si, 21so, 21t Convex part 22, 22a, 22b, 22s, 22si, 22so, 22t Concave part 30 Intermediate body 35 Stamper A1, A2,. Side area As Servo pattern area Asi Inner circumference servo pattern area Aso Outer circumference servo pattern area At Track pattern area Ati Inner circumference track pattern area Ato Outer circumference track pattern area Cls Detection clock Ds Servo data L1i to L5 , L1o～L5o length O center R arrow

Claims (6)

A servo pattern is formed by a concavo-convex pattern on at least one surface side of the substrate, and a data track pattern is formed by providing concentric or spiral data recording tracks on the one surface side,
The concavo-convex pattern constituting the servo pattern is such that the value obtained by dividing the unit convex portion length along the rotation direction of the base material by the distance from the center of the data track pattern decreases from the inner peripheral side toward the outer peripheral side. The length of the unit convex portion is defined, and the value obtained by dividing the unit concave portion length along the rotation direction by the distance from the center of the data track pattern is reduced from the inner peripheral side toward the outer peripheral side. The unit recess length is defined and the unit recess length along the rotation direction is equal to or less than the unit protrusion length along the rotation direction at the same radial position where the distance from the center of the data track pattern is equal. An information recording medium in which the unit convex part length and the unit concave part length are defined in such a manner.   2. The concave-convex pattern constituting the servo pattern is defined such that the unit concave portion length is equal or substantially equal throughout the entire area from the inner peripheral side to the outer peripheral side. Information recording medium.   The concavo-convex pattern constituting the servo pattern is defined such that the unit convex portion length is equal or substantially equal throughout the entire area from the inner peripheral side to the outer peripheral side. The information recording medium described.   4. The information recording medium according to claim 1, wherein the information recording medium is associated with the servo pattern from the information recording medium based on read frequency information defined in advance according to a distance from a center of the data track pattern. And a control unit that reads out the servo data and controls the servo.   The information recording medium according to any one of claims 1 to 3, and the read frequency information defined in advance for each of a plurality of annular regions that are concentrically divided from the inner circumference side to the outer circumference side. A recording / reproducing apparatus comprising: a control unit that reads out servo data associated with the servo pattern from an information recording medium and performs servo control.   The convex part formed corresponding to the concave part of the said uneven | corrugated pattern in the information recording medium in any one of Claim 1 to 3, and the concave part formed corresponding to the convex part of the said uneven | corrugated pattern in the said information recording medium A stamper for manufacturing an information recording medium on which a concavo-convex pattern is formed.

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