JP2006172571A - Signal pattern for magnetic transfer, magnetic recording medium and its manufacturing method, patterned master carrier for magnetic transfer to be used in the manufacturing method, and magnetic recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal pattern for magnetic transfer with which the signal pattern by bit string is recorded with precision without allowing erroneous recognition to occur by noise detection in reproducing the signal. <P>SOLUTION: The signal pattern for the magnetic transfer 10 has signals by the bit strings 11, 12 which are adjacently arranged in a track width direction r, wherein the bit string signals 11a, 112a adjacently arranged in the track width direction r are connected by a diagonal pattern 115 where an inclination angle θ relative to a direction where the gap 15a of a magnetic head 15 is extended is 20-70°. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic transfer signal pattern, a magnetic recording medium, and a method of manufacturing the same, for example, a magnetic transfer signal pattern such as an amplitude servo pattern having an amplitude reproduction type servo signal, and a magnetization bit pattern corresponding to the signal pattern. The present invention relates to a magnetic recording medium on which is recorded and a manufacturing method thereof.

  The present invention also relates to a patterned master carrier for magnetic transfer used in a method for producing a magnetic recording medium.

  Furthermore, the present invention relates to a magnetic recording / reproducing apparatus that stores a magnetic recording medium on which a magnetization bit pattern corresponding to an amplitude reproduction type servo signal is recorded.

Conventionally, a master for magnetic transfer is applied by applying a magnetic field for transfer in a state where a magnetic transfer master carrier carrying transfer information by a fine uneven pattern and a transfer medium (slave medium) having a magnetic recording layer to be transferred are in close contact with each other. A magnetic transfer method is known in which a magnetization pattern corresponding to information carried on a carrier is transferred and recorded on a slave medium. This magnetic transfer method has the advantage that recording can be performed statically without changing the relative positions of the master carrier and the slave medium, and the time required for recording is extremely short. (For example, refer to Patent Documents 1 and 2).

On the other hand, as one of the technical problems in the magnetic transfer method, there is a problem that an unclear magnetic recording portion (reversal magnetization) occurs on the magnetic recording medium in the transfer of the signal from the master carrier to the magnetic recording medium. is there. Due to the presence of the unclear magnetic recording portion, subpulses are detected in the readout waveform of the magnetization pattern, so that the magnetic reproducing apparatus may recognize the subpulses as a reproduction signal and generate an error. Methods for observing subpulses generated by the unclear magnetic recording unit are disclosed in, for example, Patent Documents 3 and 4.
JP 10-40544 A Japanese Patent Laid-Open No. 10-269566 JP 2002-93065 A Japanese Patent Laid-Open No. 2002-42301

  By the way, for example, the amplitude servo pattern used as a servo signal for track positioning of the magnetic head is adjacent to different tracks in the track width direction at intervals of about one track, as shown in Patent Documents 1 and 2. Servo burst signals by burst bit sequences arranged in the same manner, and there is a non-signal area for approximately one track between burst bit sequences arranged in different tracks. When a servo pattern is recorded, there is a problem that magnetization that causes noise is performed in the non-signal area.

  That is, when a signal pattern such as the servo burst signal as described above is recorded by magnetic transfer, there is no transfer pattern between the bit string signals arranged adjacent to each other in the track width direction. There is a problem that high noise is generated as a result of unclear and unnecessary magnetization in a region that is essentially no signal.

  Further, in the signal pattern, since bit element columns are arranged adjacent to each other in the track width direction on different tracks, when an external magnetic field for magnetic transfer is applied, the bit pattern is positioned on an intermediate track between both bit columns. Produced a magnetic field ejected from the bit elements on both sides, which was transferred and recorded on the magnetic recording medium as it was, causing noise.

  Currently, with the aim of further increasing the capacity of magnetic disk media, the track width is narrowed, and for example, a track pitch of about 200 nm or less is being realized. Along with the narrowing of the track pitch, the reproduction amplitude from each burst bit string in the case of the servo signal becomes small, and therefore the tracking positioning accuracy may be lowered due to the influence of the noise.

  In view of the above circumstances, the present invention provides a magnetic transfer signal pattern capable of accurately performing a signal pattern based on a bit string on an adjacent track without causing erroneous recognition due to noise detection during signal reproduction, and a magnetic recording on which the signal pattern is recorded It is an object of the present invention to provide a medium, a manufacturing method thereof, and a magnetic recording / reproducing apparatus using the magnetic recording medium.

  Another object of the present invention is to provide a patterned master carrier for magnetic transfer used in a method for producing a magnetic recording medium.

  According to the magnetic transfer signal pattern of the present invention, in the magnetic transfer signal pattern having the bit string signals arranged adjacent to each other in the track width direction, the gap of the magnetic head extends from the bit string signals arranged adjacent to each other in the track width direction. It is characterized by being connected in an oblique pattern having an inclination angle with respect to the direction of 20 to 70 °.

  The inclination angle of the oblique pattern is 20 to 70 °, preferably 45 to 70 °, more preferably 50 to 60 °.

  The bit string signal is preferably a servo burst signal based on a burst bit string in an amplitude servo pattern.

  Further, it is preferable that the oblique pattern is formed continuously at the end of the bit string signal.

  The magnetic recording medium of the present invention is characterized in that the magnetic transfer signal pattern of the present invention is recorded on a magnetic recording layer by magnetic transfer.

  The method of manufacturing a preformatted magnetic recording medium of the present invention has a bit string signal by a bit element string arranged adjacent to the track width direction, and the bit string signal arranged adjacent to the track width direction is a magnetic head The surface of the magnetic transfer patterned master carrier having the magnetic transfer signal pattern connected to the surface in an oblique pattern with an inclination angle of 20 to 70 ° with respect to the direction in which the gap extends, and the magnetic recording surface of the magnetic recording medium, And magnetically transferring the magnetic transfer signal pattern onto the recording surface of the magnetic recording medium by applying a magnetic field to the magnetic transfer patterned master carrier and the magnetic recording medium. It is.

  The bits on the magnetic recording medium thus magnetically transferred correspond to the bit elements on the master carrier in a 1: 1 ratio. Similarly, the bit strings on the magnetic recording medium correspond to the element strings on the master carrier. To do.

  The patterned master carrier for magnetic transfer of the present invention has bit string signals arranged adjacent to each other in the track width direction, and the bit string signals arranged adjacent to each other in the track width direction are inclined with respect to the direction in which the gap of the magnetic head extends. The magnetic transfer signal pattern is connected to the surface in an oblique pattern having an angle of 20 to 70 °.

  The magnetic recording / reproducing apparatus of the present invention includes a magnetic head, a preformatted magnetic recording medium disposed opposite to the magnetic head, means for driving the magnetic head, and means for driving the magnetic recording medium. A recording / reproducing signal processing means for transmitting / receiving a signal to / from the magnetic head for processing, wherein the preformat of the magnetic recording medium is arranged adjacent to the track width direction. Servo burst signals adjacent to each other in the track width direction are connected in a diagonal pattern with an inclination angle of 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends. It is characterized by that.

  The “pre-formatted magnetic recording medium” can be placed at a position where the magnetic head of the magnetic recording / reproducing apparatus can read and write, and the magnetic recording medium is fixed at the position except during magnetic recording / reproducing. Even if it is in the state where it was done, the state which can be attached or detached may be sufficient.

  There may be one or a plurality of burst bits constituting the burst bit element sequence in the amplitude servo pattern recorded on the magnetic recording medium. In the case of a plurality of burst bits, the recording length in the track width direction of each recording area is equal, and the track width direction The end positions at are the same. Similarly, there may be one or a plurality of burst bit elements constituting the element array formed on the surface of the patterned master carrier for magnetic transfer. In the case of a plurality of burst bit elements, the length of the upper surface of each bit element in the track width direction is the same. And the end positions in the track width direction are the same.

  The signal pattern for magnetic transfer according to the present invention is formed by connecting bit string signals arranged adjacent to each other in the track width direction in an oblique pattern having an inclination angle of 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends. Thus, the signal is inverted during magnetic transfer, the ejection of the magnetic field from the bit string signals on both sides is small, the occurrence of sub-peaks due to unclear magnetization can be prevented, and the formation of a magnetization pattern with less noise can be achieved.

  Further, the oblique magnetization pattern transferred according to the oblique pattern is inclined by 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends, so that the reproduction output when scanning this magnetization pattern is low and substantially real. In particular, it cannot be read by a magnetic head and functions as a no-signal area. In the case of a servo signal, accurate tracking based on detection of a burst signal can be performed.

  Further, in the magnetic recording medium of the present invention, the bit string signals arranged adjacent to each other in the track width direction in the recorded magnetization pattern are connected in an oblique pattern having an inclination angle of 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends. As a result, noise detection during head scanning associated with magnetization recording of a noise signal to a non-signal portion between adjacent bit string signals arranged in the track width direction can be reduced, so that detection of the magnetization signal is excellent. Yes.

  The method for producing a magnetic recording medium according to the present invention is such that a bit string signal adjacent in the track width direction by magnetic transfer using a patterned master carrier for magnetic transfer is inclined at an inclination angle of 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends. Since the magnetic transfer signal pattern connected by the pattern is recorded, it is possible to perform good bit recording in which the influence of noise on the signal reading of the magnetization pattern is reduced.

  The patterned master carrier for magnetic transfer according to the present invention is a magnetic transfer signal in which bit string signals arranged adjacent to each other in the track width direction are connected in an oblique pattern with an inclination angle of 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends. Since the pattern is provided on the surface, the magnetic recording medium of the present invention can be easily produced by using this pattern.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an enlarged view showing an amplitude servo pattern according to an embodiment of the magnetic transfer signal pattern of the present invention, and FIG. 1 shows a part of the pattern. This figure is also an enlarged view showing a part of the magnetization pattern of the servo signal of the recording / reproducing layer of the magnetic recording medium of the present invention ideally recorded with the amplitude servo pattern of the present invention.

  The amplitude servo pattern 10 (signal pattern for magnetic transfer) is recorded on the recording / reproducing layer of the magnetic recording medium. The magnetic recording medium is a disk-shaped magnetic recording medium such as a high-density flexible disk or a hard disk, and is supported. In this configuration, a recording / reproducing layer made of a magnetic layer is provided on one side or both sides of the body. In particular, in order to achieve high density, a thin layer coated magnetic layer or a metal thin film magnetic layer is preferably used as a recording / reproducing layer. The support may be flexible or hard.

  A track Tn is formed concentrically or spirally on the recording / reproducing layer of the magnetic recording medium, and the amplitude servo pattern 10 carrying the servo signal of this embodiment is recorded on the track Tn by the magnetization pattern. In the case of a magnetic disk recording medium, the amplitude servo pattern 10, that is, the servo signal is a signal recorded in a servo field formed in a narrow area extending substantially radially from the central portion at regular intervals. This signal is used for servo. The amplitude servo pattern 10 recorded with this magnetization pattern can be visualized and confirmed by means such as magnetic development as necessary.

  As shown in FIG. 1, the track Tn of the magnetic recording medium on which the amplitude servo pattern 10 is recorded is formed such that the data track D and the guard band G are sequentially adjacent in the track width direction r. A width Wt obtained by combining the width Wd of the data track D and the width Wg of the guard band G corresponds to a so-called track pitch. Here, the track pitch Wt is preferably about 200 nm or less. In the figure, a magnetic head 15 having a reproducing gap 15a is schematically shown for reference. The magnetic head 15 is positioned by a servo so as to pass the data track D. The length of the magnetic head 15 in the track width direction is generally shorter than the data track width Wd. In the figure, the arrow x indicates the track direction, and the arrow r indicates the track width direction. The arrow r corresponds to the radial direction of the magnetic disk medium.

  The amplitude servo pattern 10 is composed of tracking servo signals for position control by reproduction amplitude servo composed of A, B, C, and D bursts in order in the track direction x. FIG. 1 shows four tracks Tn + 1 to Tn. Only a portion of A burst bit string 11 and B burst bit string 12 forming A burst and B burst recorded in a part of +4 is shown, and each burst bit string 11, 12 has a plurality of rectangular burst bits 111a, 112a, respectively. , 121b, 122b, 123b. In the magnetization pattern of the magnetic recording medium, the hatched portion is the burst bit recording region, and the shaded portion and the plain portion are magnetized in opposite directions. The ratio of the length in the track direction of this one shaded portion to the length in the track direction of the plain portion up to the next shaded portion is 1: 1. These one hatched portion or one plain portion corresponds to 1 bit, and therefore 2 bits are included in the 360 ° phase.

  The recording area of the A burst bit string 11 and the B burst bit string 12 in the servo pattern 10 is arranged to extend from the approximate center in the width direction of the data track D to the approximate center in the width direction of the adjacent data track D. And B burst bit string 12 are alternately recorded in the track width direction r. The C burst bit string and D burst bit string forming the C burst and D burst (not shown) are composed of burst bits similar to those of the A and B burst bit strings 11 and 12, and one of the recording areas is an odd track. Are recorded in even tracks on the length of approximately one track pitch Wt with the center of the width of the data track D as the center.

  A plurality of burst bits constituting each burst bit string in the amplitude servo pattern 10 (for example, a plurality (five in FIG. 1) burst bits 111a constituting an A1 burst bit string straddling the track Tn + 1 and the track Tn + 2). 111a,..., Have the same recording length in the track width direction r in each recording area, and the end positions in the track width direction r are the same.

  In FIG. 1, in order to position the head 15 on the second track Tn + 2, the A1 burst bit string and the B2 burst bit string are used. The A1 burst bit string includes the first track Tn + 1 and the second track Tn + 2. The B2 burst bit string straddles the second track Tn + 2 and the third track Tn + 3. The A1 burst bit string recorded across the first track Tn + 1 and the second track Tn + 2 is also used for positioning the head 15 on the first track Tn + 1. On the other hand, the B2 burst bit string recorded across the second track Tn + 2 and the third track Tn + 3 is also used when positioning the head 15 on the third track Tn + 3. It is.

  The head 15 traveling on the second track Tn + 2 is positioned on the second track Tn + 2 by applying a position servo so that the reproduction amplitudes from the A1 burst bit string and the B2 burst bit string are equal.

  In the amplitude servo pattern 10, the A1 burst bit string recorded across the first track Tn + 1 and the second track Tn + 2, the third track Tn + 3, and the fourth track Tn + 4. The A2 burst bit string recorded across the two is recorded adjacent to each other in the track width direction r with an interval (no signal area) of approximately one track pitch width Wt. It is connected. Similarly, in the B burst bit strings of B1 to B3, adjacent B1 burst bit strings and B2 burst bit strings, and B2 burst bit strings and B3 burst bit strings with an interval corresponding to one track pitch width Wt are oblique patterns, respectively. 125 are connected.

  In the oblique patterns 115 and 125, the inclination angle θ with respect to the direction in which the gap 15a of the magnetic head 15 extends is set to 20 to 70 °, preferably 45 to 70 °, more preferably 50 to 60 °.

  When the inclination angle θ is increased, as shown in FIG. 4, the burst bits 111a and 112a that connect the burst bit strings 11 and 11 on both sides with the oblique pattern 116 are shifted by one in FIG. On the other hand, they are connected so as to be shifted by two and further by three. In this case, when the interval between the oblique patterns 116 becomes narrower as the inclination angle θ becomes larger and it becomes difficult to form (draw), the oblique patterns 116 may be thinned out as shown in FIG. .

  In this way, in each of the A, B, C, and D burst bit strings, the burst bit strings adjacent in the track width direction r (for example, the A1 burst bit string and the A2 burst bit string in the A burst bit string) are represented by diagonal patterns 115 or 116. According to the coupled amplitude servo pattern 10, the recording of this oblique pattern can prevent the occurrence of noise due to the ejection of a magnetic field from the bit string signals on both sides and the unclear magnetization reversal during magnetic transfer. As will be described later, the oblique pattern (obliquely magnetized pattern) is inclined by 20 to 70 ° with respect to the direction in which the gap 15a of the magnetic head 15 extends, so that the scanning reproduction output is low and the magnetic head 15 is substantially reduced. In this case, the oblique pattern formation portion functions as a no-signal region without noise, and accurate tracking based on detection of a burst signal can be performed.

  In the example of FIG. 1 above, the oblique patterns 115 and 125 are integrally connected to the end portions of the bit string signals on both sides without a gap, but may be connected via a slight gap.

  In the amplitude servo pattern 10, the C burst bit string and the D burst bit string (not shown) are the same, or the bit string adjacent to only the C burst bit string and the D burst bit string is an oblique pattern having the same inclination angle θ as described above. You may connect.

  In addition, each bit (element) of the burst bit string shown in FIG. 1 is rectangular, but as shown in the bit element shape shown in FIG. The shape may be rounded or may be formed in a parallelogram inclined with respect to the track width direction r.

  Further, as in the bit element shape shown in FIG. 2B, the length in the track width direction r of each recording area of the A burst bit string and the B burst bit string is made longer than the track pitch Wt and viewed in the track direction x. In this case, the recording areas of both burst bit strings may be formed so as to overlap in the track width direction r at the center portion in the width direction of the data track D.

  In this case, since each burst bit element is recorded in an area beyond the center in the width direction of the data track D as compared with the case where the burst bit is recorded with substantially the same length as the track pitch Wt, the reproduction is performed. The amplitude of the signal can be increased.

  The magnetic recording / reproducing apparatus using the magnetic recording medium on which the servo pattern according to the present invention is recorded is not shown, but includes a magnetic head, a preformatted magnetic recording medium disposed opposite to the magnetic head, and a magnetic It comprises means for driving the head, means for driving the magnetic recording medium, and recording / reproducing signal processing means for transmitting and receiving signals to and from the magnetic head. The preformat of the magnetic recording medium includes an amplitude servo pattern having a servo burst signal by a burst bit string arranged adjacent to the track width direction, and the servo burst signals arranged adjacent to each other in the track width direction are connected by an oblique pattern. As a result, the amplitude of the reproduced signal with less noise can be increased, so that a highly accurate position servo can be realized.

  Recording of the amplitude servo pattern 10 on the magnetic recording medium as described above is performed by magnetic transfer due to the arbitraryness of the burst bit shape and the like.

  Next, a method for manufacturing a magnetic recording medium in which the amplitude servo pattern 10 is recorded on a magnetic recording medium by magnetic transfer will be described with reference to FIGS. The outline of the manufacturing method is as follows. The surface of the patterned master carrier 3 for magnetic transfer having the amplitude servo transfer pattern 30 on the surface where servo burst signals arranged adjacent to different tracks as described above are connected by an oblique pattern; The magnetic recording layer 2a of the magnetic recording medium 2 is brought into close contact, and a magnetic field is applied to the magnetic transfer patterned master carrier 3 and the magnetic recording medium 2 so as to form a magnetization pattern corresponding to the amplitude servo transfer pattern 30. The magnetic recording medium 2 is magnetically transferred to the recording layer 2a.

  FIG. 2 shows a patterned master carrier 3 for magnetic transfer used for this magnetic transfer. 2A is a top view of the master carrier, FIG. 2B is an enlarged view of a part of FIG. 2A, and FIG. 2C is a sectional view taken along line III-III of FIG.

  As shown in FIG. 2 (a), the patterned master carrier 3 has a disk shape, and servo fields 4 are formed in narrow areas extending radially from the center at equal intervals. A servo transfer pattern 30 as shown in FIG. 2B is formed in the servo field 4 of the master carrier 3 by an amplitude servo pattern to be recorded, that is, an uneven pattern corresponding to the servo signal.

  FIG. 2B is a partially enlarged view of the A element row 31 and the B element row 32 corresponding to the A burst bit row and the B burst bit row equivalent to those in FIG. 1 in the servo field on the surface of the patterned master carrier 3. A track equivalent to the track on the magnetic recording medium is provided, and an uneven pattern is formed along the track. The track, data track D and guard band G corresponding to FIG. 1 and their respective widths are indicated by the same reference numerals.

  The hatched portion in FIG. 2 shows an embodiment different in shape from that in FIG. 1, but the burst bit element 112a constituting the A2 burst bit sequence is the same as the burst bit element 111a constituting the A1 burst bit sequence, respectively. It is the upper surface of the corresponding burst bit elements 311a and 312a, and the burst bit elements 321b and 322b corresponding to the burst bit element 121b of the B1 burst bit string and the burst bit element 122b of the B2 burst bit string, respectively. The A1 burst bit string is formed across the first track Tn + 1 and the second track Tn + 2, and the B2 burst bit string is formed across the second track Tn + 2 and the third track Tn + 3. Has been. The length of the upper surface of the five burst bit elements 311a of the A1 burst bit string (similarly, five burst bit elements 322b of the B2 burst bit string, etc.) in the track width direction r is longer than the track pitch Wt, and the second track Tn + 2 The lower end of the element 311a and the upper end of the element 322b are formed so as to overlap in the track width direction at the center in the track width direction. Also, this end is rounded.

  Further, in the amplitude servo transfer pattern 30, the A1 burst bit string recorded across the first track Tn + 1 and the second track Tn + 2, the third track Tn + 3, and the fourth track Tn +. The A2 burst bit string recorded over 4 is recorded adjacent to each other in the track width direction r at an interval of about one track pitch width Wt. Both bit elements 311a and 312a are oblique patterns. 315 are connected. Similarly, in the burst bit sequence 32 of B1 to B2, adjacent elements 321b and 322b are connected by an oblique pattern 325 with an interval corresponding to approximately one track pitch width Wt.

  In the oblique patterns 315 and 325, the inclination angle θ with respect to the direction in which the gap 15a of the magnetic head 15 extends is set to 20 to 70 °, preferably 45 to 70 °, more preferably 50 to 60 °, as described above. Yes.

  As shown in a partial sectional view in FIG. 2 (c), the patterned master carrier 3 includes a substrate 41 having a concavo-convex pattern on the surface and a magnetic layer 42 formed on the substrate 41. is there. In the present embodiment, the convex portion 322b of the magnetic layer 42 constitutes each element of the B burst bit string (the same applies to the A burst bit element 311a).

  The substrate 41 can be made of Ni, silicon, quartz plate, glass, aluminum, ceramics, synthetic resin, or the like, but is preferably made of Ni or an alloy containing Ni as a main component.

  As the magnetic material of the magnetic layer 42, Co, Co alloy (CoNi, CoNiZr, CoNbTaZr, etc.), Fe, Fe alloy (FeCo, FeCoNi, FeNiMo, FeAlSi, FeAl, FeTaN), Ni, Ni alloy (NiFe) should be used. Particularly preferred are FeCo and FeCoNi. In particular, Fe70Co30 is preferable. As the magnetic layer 42 disposed on the substrate 41, a magnetic layer having a small coercive force such as soft magnetism or semi-hard magnetism can be used for better transfer. Furthermore, the magnetic layer preferably has a saturation magnetization value higher than that of the substrate.

  The substrate 41 having a concavo-convex pattern on the surface can be manufactured using a stamper method, a photolithography method, or the like. In an example of manufacturing the patterned master carrier 3, first, a first master having a concavo-convex pattern corresponding to a signal pattern (including a concavo-convex pattern in which a concave portion and a convex portion are inverted) is prepared. It can be obtained by a method of producing a metal plate having the concavo-convex pattern on the surface by electroforming using a master.

  The first master having a concavo-convex pattern on the surface can be manufactured using a photolithography method or the like. Hereinafter, a method for producing a master using a silicon wafer will be described, but a quartz plate or a glass plate can be used instead of the silicon wafer.

  First, a positive electron beam resist layer is provided by spin coating or the like on a disk-shaped silicon wafer having a smooth surface. While rotating this, the resist layer is irradiated with an electron beam modulated in accordance with the signal pattern, and the entire resist layer is irradiated in the signal pattern. For example, when this signal pattern is a servo signal used for a magnetic disk, a plurality of tracks (for example, several tens of thousands) formed concentrically at regular intervals are arranged at regular intervals. Irradiation of a pattern corresponding to a servo signal extending in the circumferential direction is given to a part of each sector (for example, 200) provided. In this way, after pattern irradiation is given to the entire resist surface, the resist is developed to remove the portion of the resist irradiated with the electron beam from the silicon wafer, and the convex portion is made of resist. A silicon wafer having a concavo-convex shape in which a portion where the resist is removed and the surface of the silicon wafer is exposed forms a concave portion, that is, a first master is obtained.

  Electroforming is performed using the first master thus produced. That is, on the uneven surface of the first master, if necessary, a metal such as nickel or silver is sputtered, vapor-deposited or electrolessly plated to form a thin conductive film. Electroplate so that it is thick enough. After that, the electroplated Ni and the first master are peeled off, so that the Ni plate having a concavo-convex pattern in which the portion irradiated with the electron beam corresponding to the servo signal forms a convex portion on the surface ( Hereinafter, this is referred to as a first mold). The first mold thus obtained is used as it is, or further, a soft magnetic layer and a protective layer provided in this order on the uneven surface are used as a patterned master carrier.

  Further, the first mold is used as a second master to further perform electroforming to produce a Ni plate having an uneven surface (hereinafter referred to as a second mold), which is used as it is or on the uneven surface. In addition, a soft magnetic layer and a protective layer can be provided in this order and used as a patterned master carrier. In this case, when producing the first master, (1) use a negative type electron beam resist and irradiate the electron beam in a signal pattern corresponding to a servo signal, or (2) electron It is preferable to use a positive resist as a line resist and irradiate an electron beam in a reverse pattern of a signal pattern corresponding to a servo signal. In this aspect, there is an advantage that a plurality of patterned master carriers can be produced from the second master.

  Also, a master disk is formed by using a second master as a stamper, molding a resin disk having an uneven surface by a stamper method, and providing a soft magnetic layer and a protective layer on the uneven surface in this order. It is also possible to do.

  On the other hand, when the surface of the first master is manufactured in the same manner as described above and the surface thereof is etched, the resist forming the convex portion functions as an etching resist. Therefore, the surface of the silicon wafer corresponding to the concave portion Can be selectively etched. After the etching process is performed in this manner, the resist constituting the convex portion is removed to obtain a third master having a concave / convex pattern on the surface of the silicon wafer itself. By performing electroforming in the same manner as described above using this third master, a Ni plate (third mold) having irregularities on the surface can be produced. The third mold can be used as it is, or further, a soft magnetic layer and a protective layer can be provided in this order on the uneven surface to form a master carrier. Also in this aspect, a plurality of master carriers can be produced from the third master.

  The height of the convex portion (depth of the concave / convex pattern) of the master carrier 3 is preferably in the range of 20 to 500 nm, more preferably 40 to 100 nm. When this uneven pattern is a sample servo signal, a rectangular convex portion that is longer in the radial direction than the circumferential direction that is the track direction is formed.

  The soft magnetic layer is formed on the concave / convex pattern of the substrate using a soft magnetic material such as a vacuum deposition method such as vacuum deposition, sputtering or ion plating, or a plating method such as electroplating or electroless plating. Do it. The thickness of the soft magnetic layer (the thickness of the magnetic layer on the top surface of the convex portion) is preferably in the range of 20 to 500 nm, more preferably 30 to 100 nm.

  Further, it is preferable to provide a protective layer such as carbon of 30 to 30 nm or diamond-like carbon (DLC) on the magnetic layer 42 on the surface of the convex portion, and a lubricant layer may be further provided. Further, an adhesion reinforcing layer such as Si may be provided between the soft magnetic layer and the protective layer. By providing the lubricant, it is possible to suppress the occurrence of scratches due to friction when correcting the deviation caused in the contact process with the magnetic recording medium, and to further improve the durability.

  Note that the configuration of the patterned master carrier 3 for magnetic transfer is not limited to that of the master carrier of the above embodiment, and basically any carrier having a servo signal as a concavo-convex pattern and having a concavo-convex pattern on the surface. A magnetic substrate alone, a substrate having a concavo-convex pattern on its surface and a magnetic layer laminated on at least the top of the convex portion on the substrate, a non-magnetic substrate having a concavo-convex pattern on its surface, and a concave portion of the substrate It may be formed of an embedded magnetic layer, or may be formed by forming a magnetic layer having a concavo-convex pattern on a flat substrate. In the case of a patterned master carrier comprising a nonmagnetic substrate having a concavo-convex pattern on the surface and a magnetic layer embedded in a recess, the bit element is constituted by a magnetic layer embedded in the recess.

  Next, a method for recording a magnetic pattern on the magnetic disk recording medium 2 by using the above-described patterned master carrier 3 for magnetic transfer will be described with reference to FIG.

  FIG. 3 is a diagram for explaining the basic steps of this magnetic transfer. FIG. 3 (a) is a step of applying a magnetic field in one direction to initial DC magnetization of the magnetic recording medium, and FIG. A step of applying a magnetic field in a direction opposite to the initial magnetization direction by bringing the carrier and the magnetic recording medium into close contact with each other, and FIG.

  First, as shown in FIG. 3A, an initial magnetic field Hin is applied to the magnetic recording medium 2 in one direction in the track direction in advance to cause the magnetization of the magnetic recording layer 2a to be initially magnetized in the one direction. Thereafter, as shown in FIG. 3B, the recording surface of the magnetic recording medium 2 and the transfer pattern surface of the master carrier 3 are brought into close contact with each other, and the initial magnetic field Hin is opposite to the track direction of the magnetic recording medium 2. A transfer magnetic field Hdu is applied. At a location where the recording surface of the magnetic recording medium 2 and the convex portion of the transfer pattern of the master carrier 3 are in close contact with each other, the magnetic field Hdu is sucked into the convex magnetic layer 42 of the master carrier 3 and the magnetic recording medium 2 corresponding to this portion. The magnetization of the magnetic recording layer 2 a is not reversed, and the magnetization of the magnetic recording layer 2 a corresponding to the concave portion of the master carrier 3 is reversed by the leakage magnetic field from the convex portion of the master carrier 3. As a result, as shown in FIG. 3C, a magnetic pattern corresponding to the uneven pattern on the surface of the master carrier 3 is magnetically transferred and recorded on the magnetic recording layer 2a of the magnetic recording medium 2.

  Note that the initial magnetic field and the magnetic field for transfer need to adopt values determined in consideration of the coercivity of the magnetic layer of the magnetic recording medium and the relative magnetic permeability of the magnetic layer of the master carrier and the magnetic recording medium.

  As in the servo transfer pattern 30 in FIG. 2B, it has been difficult to record bits with rounded ends by a conventional recording method using a servo track writer. This can be easily achieved by using magnetic transfer. Note that the amplitude servo magnetization pattern 10 of FIG. 1 can be recorded in a shorter time and with higher accuracy by using magnetic transfer as compared with the case of recording with a servo track writer.

  Here, based on FIG. 5, it will be explained that the oblique patterns 115 a and 115 b obtained by connecting the burst bit strings on both sides are not substantially read by the magnetic head 15. Table 1 shows the relationship between the inclination angle θ of the oblique pattern and its output characteristics.

  As shown in FIG. 5, in the magnetized oblique patterns 115a and 115b in the magnetic recording medium, one side edge and the opposite side edge are charged with opposite polarities. When the magnetic head 15 moves as shown in FIGS. 5A to 5C, a gap 15a is applied to both edges of the first oblique pattern 115a at the point (a). The opposite polarities of the edges cancel each other and no output is generated. Further, at point (b), a gap 15a is applied to one edge of the first oblique pattern 115a and one edge of the second oblique pattern 115b, and reading in this state cancels the opposite polarities of both edges, No output is generated.

  Next, at point (c), a gap 15a is applied to one edge at the end of one diagonal pattern 115a, and in this state reading, the charge polarity of this edge is detected and a weak output is generated. However, as shown in Table 1, this output is a charge density output in which the edge length increases as the tilt angle θ increases, as compared to the read output of the pattern in the vertical state: Second, the head cover length output by the track width correction of the head cover length of the magnetic head 15 is reduced by dB, and the output difference from the vertical pattern of the total output: dB is greatly reduced by the output reduction from both. If the read output is significantly lower than -8 dB, the read output is not substantially obtained.

As a result of Table 1, the total output decrease due to the inclination angle θ and the charge density and the output decrease due to the head cover length is significantly lower than −8 dB when the inclination angle θ is 20 ° or more, and is in the vicinity of −20 dB. An inclination angle θ of 60 ° is preferable, and an oblique pattern that cannot be read by the magnetic head can be obtained. When the inclination angle θ exceeds 70 °, particularly 80 ° or more, the oblique pattern width becomes narrow, which is difficult to form and is not practical.

The partially expanded view which shows the amplitude servo pattern of one Embodiment of the signal pattern for magnetic transfer of this invention Top view, partially enlarged top view, and partially sectional view of a patterned master carrier for magnetic transfer Diagram showing basic steps of magnetic transfer method The partially expanded view which shows other embodiment of the signal pattern for magnetic transfer of this invention The figure explaining the reading characteristic of the diagonal pattern part of a magnetization pattern

Explanation of symbols

2 Magnetic recording medium 3 Master carrier for magnetic transfer
10 Signal pattern for magnetic transfer (amplitude servo pattern)
30 Transfer pattern
11,12,31,32 Burst bit string
111a, 112a, 121b, 122b, 123b Burst bit
115,116,125 Diagonal pattern
311a, 312a, 321b, 322b Burst bit element
315,325 Diagonal pattern

Claims (7)

In a magnetic transfer signal pattern having a bit string signal arranged adjacent to the track width direction,
A signal pattern for magnetic transfer, wherein the bit string signals arranged adjacent to each other in the track width direction are connected in an oblique pattern having an inclination angle of 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends.   2. The magnetic transfer signal pattern according to claim 1, wherein the bit string signal is a servo burst signal based on a burst bit string in an amplitude servo pattern.   3. The signal pattern for magnetic transfer according to claim 1, wherein the oblique pattern is formed continuously at an end of the bit string signal.   4. A magnetic recording medium, wherein the magnetic transfer signal pattern according to claim 1 is recorded on a magnetic recording layer by magnetic transfer. It has a bit string signal by bit element strings arranged adjacent to each other in the track width direction, and the bit string signals arranged adjacent to each other in the track width direction are inclined at an inclination angle of 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends. Adhering the surface of the patterned master carrier for magnetic transfer having the magnetic transfer signal pattern connected by the pattern to the magnetic recording surface of the magnetic recording medium,
A preformatted magnetism characterized in that a magnetic field is applied to the magnetically transferred patterned master carrier and the magnetic recording medium, and the magnetic transfer signal pattern is magnetically transferred to the recording surface of the magnetic recording medium. A method for manufacturing a recording medium.   It has bit string signals arranged adjacent to each other in the track width direction, and the bit string signals arranged adjacent to each other in the track width direction are connected in an oblique pattern with an inclination angle of 20 to 70 ° with respect to the direction in which the gap of the magnetic head extends. A patterned master carrier for magnetic transfer, comprising a magnetic transfer signal pattern on the surface. A signal between the magnetic head, a preformatted magnetic recording medium disposed opposite to the magnetic head, means for driving the magnetic head, means for driving the magnetic recording medium, and the magnetic head A recording / reproducing signal processing means for receiving and processing
The preformat of the magnetic recording medium includes an amplitude servo pattern having a servo burst signal by a burst bit string arranged adjacent to the track width direction, and the servo burst signal arranged adjacent to the track width direction A magnetic recording / reproducing apparatus characterized in that the magnetic recording / reproducing apparatus is connected in an oblique pattern with an inclination angle of 20 to 70 ° with respect to the direction in which the two extend.

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