JP2006277891A - Method for manufacturing magnetic transfer master disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a master disk bearing information to be transferred by magnetic transfer, capable of transferring the shape of an uneven pattern on an original disk well in electroforming, and preventing the generation of internal stress in an electroforming layer, and having high flatness and high adhesion to the slave disk of a transfer destination. <P>SOLUTION: The method executes an electroforming process to obtain a master substrate which is a metal board having an uneven pattern corresponding to transfer information transferred to its surface from an inversion mold having the inversion uneven pattern, and forms a magnetic layer on the uneven pattern of the master substrate. This method includes the process of forming a conductive layer on the surface of the inversion mold 17, the process of applying a dummy liquid D on the surface of the conductive layer of the reverse mold to cover roughly the full surface of the reverse uneven pattern therewidth, the process of dipping the reverse mold having the dummy liquid D applied thereon in the liquid tank 64 of the electroforming device 60, and the process of executing electroforming by setting conduction between the inversion uneven pattern of the inversion mold dipped in the liquid tank of the electroforming device and the cathode of a plating power source. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a magnetic transfer master disk, and more particularly to a method of manufacturing a magnetic transfer master disk suitable for transferring magnetic information such as format information to a magnetic disk used in a hard disk device or the like.

  In recent years, magnetic disks (hard disks) used in hard disk drives, which have been rapidly spreading, are written with format information and address information before being installed in the drive after being delivered to the drive manufacturer by the magnetic disk manufacturer. It is common. Although this writing can be performed by a magnetic head, a method of batch transfer from a master disk in which format information and address information are written is efficient and preferable.

  In this magnetic transfer method for batch transfer, a magnetic disk generating means such as an electromagnet device or a permanent magnet device is disposed on one or both surfaces of a master disk and a disk to be transferred (slave disk) in close contact with each other. By applying a magnetic field, the information (for example, servo signal) that the master disk has is magnetically transferred to the slave disk. In order to perform magnetic transfer with high accuracy, it is extremely important that the master disk and the slave disk are in close contact with each other without gaps.

By the way, as a master disk used in this magnetic transfer method, a rugged pattern corresponding to an information signal is formed on the surface of a substrate and a magnetic layer is coated on the rugged pattern surface. This master disk for magnetic transfer is electroformed by performing electroforming on an original plate on which information is formed in a concavo-convex pattern, and laminating a metal plate made of an electroformed layer on the original plate and transferring the concavo-convex pattern onto the surface of the metal plate. It is generally manufactured by coating a magnetic layer on the surface of the concavo-convex pattern after passing through a process, a peeling process for peeling the metal disk from the original plate, and a punching process for punching the peeled metal disk to a predetermined size. (For example, refer to Patent Document 1).
JP 2001-256644 A

  However, the conventional master disk manufactured by the above process often has a problem in that the shape transfer of the uneven pattern on the original plate is not satisfactorily performed during electroforming. Specifically, when the original is immersed in the liquid tank of the electroforming apparatus, fine bubbles remain on the surface of the original, and by performing electroforming in this state, the portion where the bubbles are present is electroformed metal. There is a case where the shape of the transferred concavo-convex pattern is lost without being filled.

  On the other hand, physical (for example, stirring in the bubbles) or chemical means (for example, a surfactant) for eliminating such bubbles are also conceivable, but the results of the implementation of such means are not satisfactory. There wasn't.

  Therefore, it is very difficult to transfer a signal with high quality even if the master disk and the slave disk in which such a shape collapse is brought into close contact with each other without any gap and magnetic transfer is performed.

  In addition, internal stress is easily generated in the electroformed layer during electroforming, and the master disk is not necessarily flat due to deformations that occur during processing such as a peeling process for peeling the metal disk from the original plate or a punching process for punching to a predetermined size. It has warpage and distortion, not a surface. Even if magnetic transfer is performed by closely contacting such a master disk and slave disk without gaps, if the adhesion is low, the signal strength transferred for spacing between the master disk and the slave disk is low. There is also a problem that the transfer becomes low and good transfer cannot be performed.

  The present invention has been made in view of such circumstances, and is a master disk carrying information to be transferred by magnetic transfer, and when the electroforming is performed, the shape transfer of the concavo-convex pattern on the original is favorably performed, It is another object of the present invention to provide a master disk that is less likely to cause internal stress in an electroformed layer, is highly flat, and has high adhesion to a slave disk for transfer.

  In order to achieve the above object, the present invention provides a master substrate which is a metal disk having a concavo-convex pattern corresponding to transfer information transferred to the surface by an electroforming process using an electroforming apparatus from a reversing mold having a concavo-convex pattern In the manufacturing method of a master disk for magnetic transfer in which a magnetic layer is formed on the concave / convex pattern of the master substrate, a step of forming a conductive layer on the surface of the inversion type, and a surface of the surface of the inversion type conductive layer Applying a dummy liquid and covering substantially the entire surface of the inverted concavo-convex pattern with the dummy liquid; immersing the inverted mold coated with the dummy liquid in a liquid tank of the electroforming apparatus; and There is provided a method for producing a master disk for magnetic transfer, comprising the step of performing electroforming by conducting electrical continuity between the inversion pattern of the inversion type immersed in a liquid tank and a cathode of a plating power source. .

  According to the present invention, before the master substrate is immersed in the liquid tank of the electroforming apparatus, the dummy liquid is applied to the surface of the reverse conductive layer of the master substrate and the substantially entire surface is covered with the dummy liquid. There is no problem that fine bubbles remain on the surface. Thereby, when performing electroforming, the shape transfer of the uneven | corrugated pattern on a negative | original plate is made favorable.

  In the present invention, the dummy liquid is preferably a liquid containing water as a main component. Such a liquid containing water as a main component is easily available and inexpensive, has a low vapor pressure and is stable, and is preferable from the viewpoint of safety. In addition, as water, various things, such as ultrapure water, primary pure water, distilled water, natural water, tap water, are employable.

  In the present invention, it is preferable that conduction between the inversion-type inversion concavo-convex pattern and the cathode of the plating power source is made through a conductive ring in contact with an outer peripheral portion of the inversion concavo-convex pattern. If contact (conduction) is made through such a conductive ring, the apparatus is simple and the operation is also easy.

  In the present invention, the inversion type is preferably a substrate having a conductive layer formed by sputtering on the surface of a silicon wafer. Such an inversion type made of a silicon wafer is easy to manufacture with high accuracy and is easily available.

  As described above, according to the present invention, when the master substrate is immersed in the liquid tank of the electroforming apparatus, there is no problem that fine bubbles remain on the surface of the inversion-type conductive layer. The concavo-convex pattern on the original plate can be transferred in a satisfactory manner.

  The preferred embodiments of the method for manufacturing a magnetic transfer master disk according to the present invention will be described below in detail with reference to the accompanying drawings.

  1 is a partial perspective view of a magnetic transfer master disk 10 (hereinafter referred to as a master disk 10) according to the present invention. FIG. 2 is a cross-sectional view taken along the line AA of FIG. The slave disk 14) is indicated by an imaginary line.

  As shown in FIGS. 1 and 2, the master disk 10 is composed of a metal master substrate 11 and a magnetic layer 12, and a fine uneven pattern P (for example, a servo) corresponding to transfer information on the surface of the master substrate 11. Information pattern), and the concave / convex pattern P is covered with the magnetic layer 12.

  Thereby, the information carrying surface 13 having the fine uneven pattern P in which the magnetic layer 12 is coated on one surface of the master substrate 11 is formed. As can be seen from FIG. 1, this fine uneven pattern P is rectangular in plan view, with the magnetic layer 12 formed, the length p in the track direction (arrow direction in the figure) and the length in the radial direction. L.

  The optimum values of the length p and the length L vary depending on the recording density and the recording signal waveform. For example, the length p can be 80 nm and the length L can be 200 nm. In the case of a servo signal, the fine uneven pattern P is formed long in the radial direction. In this case, for example, the length L in the radial direction is preferably 0.05 to 20 μm, and the length p in the track direction (circumferential direction) is preferably 0.01 to 5 μm.

  It is preferable for the pattern carrying the servo signal to select the concave / convex pattern P that is longer in the radial direction within this range. The depth t (projection height) of the uneven pattern P is preferably in the range of 30 to 800 nm, and more preferably in the range of 50 to 300 nm.

  As shown in FIG. 3, the master substrate 11 is formed in a disk shape having a center hole 11G and is a circle excluding the inner peripheral portion 11D and the outer peripheral portion 11E of the one side (information carrying surface 13). The uneven pattern P is formed in the annular region 11F. The details of the production of the master substrate 11 will be described later. Mainly, the metal plate is formed by electroforming the original plate on which the information is formed by the concavo-convex pattern P, and the electroplating layer is formed on the original plate. It is manufactured by an electroforming process for transferring the uneven pattern P to the board and a peeling process for peeling the metal board from the original plate.

  In the present invention, various types of metals and alloys can be used as the electroformed layer. In the present embodiment, an example of a Ni electroformed layer will be described below as a preferable example. Since this Ni electroformed layer has flexibility, electroforming is performed while controlling the current density during electroforming so as to have a defined crystal structure. The current density during electroforming will be described later.

  Next, a method for manufacturing the master disk 10 of the present invention configured as described above will be described in detail.

  FIG. 4 is a process diagram showing steps for manufacturing the master disk 10. First, as shown in FIG. 4A, pretreatment such as formation of an adhesion layer is performed on an original plate 15 (which may be a glass plate or a quartz plate) made of a silicone wafer having a smooth and clean surface, and an electron beam resist. The liquid is applied by spin coating or the like to form a resist film 16 and baked.

  Then, an electron beam exposure apparatus (not shown) equipped with a high-precision rotary stage or XY stage irradiates the original plate 15 mounted on the stage with an electron beam B modulated in accordance with a servo signal or the like. Then, a desired concavo-convex pattern P ′ is drawn and exposed on the resist film 16.

  Next, as shown in FIG. 4B, the resist film 16 is developed, and a desired concavo-convex pattern P ′ is formed by the resist film 16 remaining after removing the exposed portion. An Ni conductive film (not shown) is applied on the concavo-convex pattern P ′ by, for example, stamping to produce an electroformed original plate 17.

  Next, as shown in FIG. 4C, the entire surface of the original plate 17 is subjected to an electroforming process by an electroforming apparatus, and a metal plate 18 (Ni electroformed layer) having a desired thickness made of Ni metal is laminated. Ni has a crystal structure of a face-centered cubic lattice and is electroformed so as to have a prescribed crystal structure by controlling the current density during electroforming.

  FIG. 5 is a cross-sectional view of the electroforming apparatus 60. The electroforming apparatus 60 is filled with a plating tank 64 for storing a plating solution (bath) 62, a drain tank 66 for receiving the plating solution 62 overflowed from the plating tank 64, and Ni pellets 68, 68. The anode chamber 70 receives the plating solution 62 overflowed from the plating tank 64, the cathode 72 holding the original plate 17, and the like.

  A plating solution 62 is supplied to the plating tank 64 from a plating solution supply pipe 74. Further, the plating solution 62 overflowed from the plating tank 64 to the drain tank 66 is recovered from the drain tank drain pipe 76. Further, the plating solution 62 overflowed from the plating tank 64 to the anode chamber 70 is recovered from the anode chamber drain pipe 78.

  The plating tank 64 and the anode chamber 70 are separated by a partition plate 80. An electrode shielding plate 82 is fixed to the surface of the partition plate 80 on the plating tank 64 side so as to face the cathode 72. The electrode shielding plate 82 is formed so as to cover a predetermined portion of the electrode so that the electroformed film thickness is uniform in the plane.

  In the electroforming apparatus 60 configured as described above, the master substrate is held by holding the original plate 17 (not shown) on the cathode 72, connecting the negative electrode to the cathode 72, and connecting the positive electrode of the anode chamber 70 to energize. 11 electroforming is performed.

  Next, the detailed structure of the cathode 72 will be described. FIG. 6 is a cross-sectional view showing the configuration of the cathode 72. The cathode 72 includes a cathode body 84 that is a disk-shaped member having a flange portion 84 </ b> A, a conductive ring 86, a pressing ring 88, and a shaft 90.

  In the state (posture) of FIG. 6, the original plate 17 can be placed on the surface of the cathode body 84. As the material of the cathode main body 84, various metal members that do not cause alteration such as rust due to use in the electroforming apparatus 60 can be adopted.

  The conductive ring 86 is a ring-shaped member having substantially the same thickness as that of the original plate 17, and has an inner diameter size substantially the same as the outer diameter size of the original plate 17. As a material of the conductive ring 86, various metal members that do not cause deterioration such as rust due to use in the electroforming apparatus 60, such as stainless steel, can be employed.

  The presser ring 88 is a ring member having a shape that can prevent the conductive ring 86 and the original plate 17 from being detached from the cathode body 84 when set on the cathode body 84 (for example, fixed to the cathode body 84 with a bolt member (not shown)). . As a material of the presser ring 88, various resin materials such as polyvinyl chloride (PVC) can be adopted.

  In FIG. 6, the inner diameter of the flange 88 </ b> A of the presser ring 88 is slightly smaller than the outer diameter of the original plate 17, so that the plating on the substantially entire surface of the original plate 17 is not hindered.

  The shaft 90 is a cylindrical member that is detachably set at the center of the lower surface of the cathode body 84. As the material of the shaft 90, various metal members that do not change in quality such as rust due to use in the electroforming apparatus 60 can be adopted.

  Next, preparation work for the electroforming process will be described. In the present invention, the electroforming step includes a step of applying the dummy liquid D to the surface of the original plate 17 (reversal type) and covering the substantially entire surface of the reverse concavo-convex pattern with the dummy liquid D, and electroforming the original plate 17 coated with the dummy liquid D. It comprises a step of immersing in the original plate 17 of the apparatus 60, and a step of performing electroforming by establishing conduction between the reverse concavo-convex pattern of the original plate 17 immersed in the original plate 17 of the electroforming apparatus 60 and the cathode of the plating power source.

  FIG. 7 is an explanatory view showing a method of immersing the cathode 72 in the plating tank 64 of the electroforming apparatus 60. Among these, (A) shows a state in which the original plate 17 and the conductive ring 86 are set on the cathode main body 84 and fixed by the presser ring 88. The shaft 90 is not attached.

  Next, as shown in FIG. 7A, the dummy liquid D is supplied to the upper surface of the original plate 17. As the dummy liquid D, various kinds of liquids such as ultrapure water, primary pure water, distilled water, natural water, tap water, etc. can be used, but use of ultrapure water is used to prevent contamination of the plating tank 64 and the like. Is preferred.

  Note that a small amount of a surfactant that lowers the surface tension of the dummy liquid D is added to the dummy liquid D so that the dummy liquid D does not leak on the upper surface of the original 17 and fine bubbles do not remain on the surface of the original 17. You can also.

  A surfactant that lowers the surface tension of the plating solution (bath) 62 can also be added to the plating solution (bath) 62 with the expectation of the same action, but a large amount of the plating solution (bath) 62 is deteriorated (contaminated). ) On the other hand, since the usage amount of the dummy liquid D is small, such a problem does not occur.

  Next, as shown in FIG. 7B, when the dummy liquid D is supplied to the upper surface of the original plate 17, a substantially entire upper surface of the original plate 17 is covered with the dummy liquid D.

  Next, as shown in FIG. 7C, the cathode 72 is immersed in the plating tank 64 of the electroforming apparatus 60. Unlike the illustration, the cathode 72 may be inclined and immersed in the plating tank 64. In this way, the cathode 72 is immersed in the plating tank 64, whereby the dummy liquid D on the upper surface of the original plate 17 is replaced with the plating liquid (bath) 62.

  Next, in the plating tank 64, the shaft 90 is mounted on the back surface of the cathode 72, and the cathode 72 is set in the state shown in FIG. With the series of operations described above, a preparation state is reached in which electroforming can be started.

  In electroforming, in this embodiment, the current density during electroforming is controlled by the pattern shown in FIG. That is, the electroforming process is divided into three or more time zones, and the initial electroforming process 50 for performing electroforming at a current density of 65% or less of the average current density of all electroforming processes for a predetermined time from the start, An electroforming process performed for a predetermined time after the electroforming process, in which electroforming is performed at a current density of 140% or more of the average current density of the entire electroforming process, and for a predetermined time until the end, A final electroforming step 54 in which electroforming is performed at a current density of 50% or less of the average current density of the electroforming step.

  FIG. 8 is an XY graph with time on the horizontal axis and current density on the vertical axis. A time 50T of the initial electroforming process 50, a time 52T of the main electroforming process 52, and a time 54T of the final electroforming process 54 are shown.

The time 50T of the initial electroforming process 50 is preferably 30 to 75% of the total electroforming process, and the time 54T of the final electroforming process 54 is 5 to 10% of the total electroforming process. It is preferable to do. Moreover, it is preferable that the average current density of all the electroforming processes shall be 5-15 A / dm < ² >.

  In this way, by controlling the current density and time of the electroforming process, internal stress is hardly generated in the electroformed layer, and the flatness of the disc after electroforming can be maintained with very high accuracy (flatness is reduced). . In addition, the surface roughness of the disc after electroforming can be maintained with very high accuracy (small surface roughness). Furthermore, the electroforming speed can be maintained as in the conventional case, and the productivity is not inferior.

  If the current density in the initial electroforming process 50 exceeds 65% of the average current density in the entire electroforming process, an internal stress is generated in the electroformed layer, which is not preferable. When the average current density is more than 50% of the total electroforming process, the surface roughness of the disk after electroforming is inferior, which is not preferable.

  Further, if the time 50T of the initial electroforming process 50 is less than 30% of the total electroforming process, internal stress is generated in the electroformed layer, which is not preferable, and the time 50T is 75% of the total electroforming process. If the time is exceeded, the productivity is inferior, which is not preferable.

  Similarly, if the time 54T of the final electroforming process 54 is set to be less than 5% of the time of the entire electroforming process, the surface roughness of the disc after electroforming is inferior. If the time exceeds 10%, the productivity is inferior, which is not preferable.

  The “average current density of all electroforming process” is a value obtained by dividing the accumulated current density of all electroforming processes by the time of all electroforming processes, and the area of the graph in FIG. It is also the value divided by time.

  Returning to FIG. 4, next, the metal plate 18 having the crystal structure defined as described above is peeled off from the original plate 17, and the remaining resist film 16 is removed and washed. As a result, as shown in FIG. 4D, the master 11 ′ of the master substrate 11 having the inverted concavo-convex pattern P and having the outer diameter D before being punched into a predetermined size is obtained.

  This master 11 'is punched out to obtain a master substrate 11 of a predetermined size having an outer diameter d shown in FIG. 4 (e). The master disk 10 can be manufactured by forming the magnetic layer 12 on the concave / convex pattern surface of the master substrate 11.

  As another manufacturing process of the master disk 10, the original plate 17 is electroformed to produce a second original plate. Then, electrocasting is performed using the second original plate, a metal disk having an inverted concavo-convex pattern is produced, and a master substrate may be punched into a predetermined size.

  Furthermore, the second original plate is electroformed, or the resin liquid is pressed and cured to produce a third original plate, and the third original plate is electroformed to produce a metal plate, and the inverted uneven pattern It is also possible to peel off a metal plate having a master substrate. A plurality of metal plates 18 can be produced by repeatedly using the second original plate or the third original plate.

  In the production of the original, the resist film may be removed after the resist film is exposed and developed, and then etched to form an uneven pattern by etching on the surface of the original.

  The magnetic layer 12 is formed by depositing a magnetic material by vacuum film forming means such as vacuum deposition, sputtering, or ion plating, or by plating, coating, or the like. As the magnetic material of the magnetic layer, Co, Co alloy (CoNi, CoNiZr, CoNbTaZr, etc.), Fe, Fe alloy (FeCo, FeCoNi, FeNiMo, FeAlSi, FeAl, FeTaN, etc.), Ni, Ni alloy (NiFe, etc.) are used. Can be used. In particular, FeCo and FeCoNi can be preferably used. The thickness of the magnetic layer 12 is preferably in the range of 50 to 500 nm, and more preferably in the range of 100 to 400 nm.

  A protective film such as diamond-like carbon (DLC) or sputtered carbon is preferably provided on the magnetic layer 12, and a lubricant layer may be further provided on the protective film. In this case, it is preferable to use a DLC film having a thickness of 3 to 30 nm and a lubricant layer as the protective film.

  Further, an adhesion enhancing layer such as Si may be provided between the magnetic layer and the protective film. The lubricant has an effect of improving deterioration of durability such as generation of scratches due to friction when correcting the deviation caused in the contact process with the slave disk 14.

  In the present invention, in the lamination of the metal plate 18 by electroforming, the current density and time are controlled so that a Ni electroformed layer having a very small residual stress is formed.

  Usually, the metal used for the master disk 10 is nickel (Ni). However, when the master disk 10 is manufactured by electroforming, a nickel sulfamate bath in which a master substrate 11 having a small stress can be easily obtained is used. Is preferred.

  The nickel sulfamate bath may contain, for example, an additive such as a surfactant (for example, sodium lauryl sulfate) based on 400 to 800 g / L of nickel sulfamate and 20 to 50 g / L of boric acid (supersaturated). It is what was added. The bath temperature of the plating bath is preferably 40 to 60 ° C. It is preferable to use a nickel ball in a titanium case for the counter electrode during electroforming.

  Next, a magnetic transfer method for transferring the uneven pattern P of the master disk 10 manufactured as described above to the slave disk 14 will be described. FIG. 9 is a perspective view of a main part of a magnetic transfer apparatus 20 for performing magnetic transfer using the master disk 10 of the present invention.

  At the time of magnetic transfer, the slave surface (magnetic recording surface) of the slave disk 14 after initial DC magnetization described later shown in FIG. 11A is brought into contact with the information carrying surface 13 of the master disk 10 to obtain a predetermined pressing force. Adhere with. Then, with the slave disk 14 and the master disk 10 in close contact with each other, a magnetic field for transfer is applied by the magnetic field generating means 30 to transfer the concave / convex pattern P of the master disk 10 to the slave disk 14.

  The slave disk 14 is a disk-shaped recording medium such as a hard disk or a flexible disk having a magnetic recording layer formed on both sides or one side. A cleaning process (burnishing or the like) for removing adhering dust is performed as necessary.

  As the magnetic recording layer of the slave disk 14, a coating type magnetic recording layer, a plating type magnetic recording layer, or a metal thin film type magnetic recording layer can be adopted. Magnetic materials for the metal thin film type magnetic recording layer include Co, Co alloys (CoPtCr, CoCr, CoPtCrTa, CoPtCrNbTa, CoCrB, CoNi, etc.), Fe, Fe alloys (FeCo, FePt, FeCoNi, etc.), Ni, Ni alloys (NiFe Etc.) can be used.

  These are preferable because they have a high magnetic flux density and have magnetic field anisotropy in the same direction as the magnetic field application direction (in-plane direction for in-plane recording), thereby enabling clear transfer. In order to provide the necessary magnetic anisotropy under the magnetic material (on the support side), it is preferable to provide a nonmagnetic underlayer. This underlayer needs to match the crystal structure and lattice constant to the magnetic layer 12. For that purpose, it is preferable to use Cr, CrTi, CoCr, CrTa, CrMo, NiAl, Ru or the like.

  The magnetic transfer by the master disk 10 is performed when the master disk 10 is brought into close contact with one side of the slave disk 14 and the transfer is performed on one side of the slave disk 14. There are cases where simultaneous transfer is performed.

  The magnetic field generating means 30 for applying the transfer magnetic field includes electromagnet devices 34, 34 each having a coil 33 wound around a core 32 having a gap 31 extending in the radial direction between the slave disk 14 and the master disk 10 held in close contact with each other. A magnetic field for transfer having magnetic field lines G (see FIG. 10) parallel to the track direction is applied in the same direction in the vertical direction. FIG. 10 shows the relationship between the circumferential tracks 14A, 14A...

  When a magnetic field is applied, a magnetic field for transfer is applied by the magnetic field generating means 30 while rotating the slave disk 14 and the master disk 10 together, and the uneven pattern of the master disk 10 is magnetically transferred to the slave surface of the slave disk 14. . In addition to this configuration, the magnetic field generation means may be rotated.

  The transfer magnetic field does not have any magnetic field strength exceeding the maximum value in the optimum transfer magnetic field strength range (0.6 to 1.3 times the coercive force Hc of the slave disk 14) in any of the track directions. There are at least one portion having a magnetic field strength within the range in one track direction, and the magnetic field strength in the opposite track direction is less than the minimum value in the optimum transfer magnetic field strength range at any position in the track direction. A magnetic field having a certain magnetic field intensity distribution is generated in a part of the track direction.

  FIG. 11 is an explanatory diagram for explaining the basic steps of a magnetic transfer method using in-plane recording. First, as shown in FIG. 11A, initial magnetization (DC demagnetization) is applied to the slave disk 14 in advance by applying an initial magnetic field Hi in one direction in the track direction.

  Next, as shown in FIG. 11B, the recording surface (magnetic recording portion) of the slave disk 14 and the information carrying surface 13 on which the concave / convex pattern P of the master disk 10 is formed are brought into close contact with each other. Magnetic transfer is performed by applying a transfer magnetic field Hd in the direction opposite to the initial magnetic field Hi in the track direction. The transfer magnetic field Hd is sucked into the magnetic layer 12 of the convex part of the concavo-convex pattern P and the magnetization of this part is not reversed, and the magnetic field of the other part is reversed. As a result, as shown in FIG. The uneven pattern P of the master disk 10 is magnetically transferred and recorded on the magnetic recording surface of the disk 14.

  In such a magnetic transfer, it is important for high-precision transfer that the slave disk 14 and the master disk 10 are closely adhered, but in the case of the present invention, a transfer uneven pattern due to bubbles or the like during electroforming. By using the master disk 10 having an accurate magnetic pattern and having a high flatness, good adhesion can be achieved.

  As mentioned above, although embodiment of the manufacturing method of the master disk for magnetic transfer concerning this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  For example, the configurations of the electroforming apparatus 60, the cathode 72, and the like are examples, and various other configurations may be used.

  In the present embodiment, the entire electroforming process is divided into three time zones of an initial electroforming step 50, a main electroforming step 52, and a final electroforming step 54. It is also possible to adopt a method of dividing into two. As described above, it is also preferable to divide into a large number of time zones and perform finer control.

  In the present embodiment, the back surface of the master disk 10 is not processed, but an embodiment in which the back surface of the master disk 10 is subjected to machining or the like so as to eliminate the plate thickness deviation can be employed.

  Furthermore, although the master disk 10 of the present embodiment is an annular (doughnut) shape having an inner diameter, it may be a disk shape having no inner diameter.

Partial perspective view of the master disk of the present invention Sectional drawing along the AA line of FIG. Plan view of master board Process drawing in one Embodiment of the manufacturing method of the master disk of this invention Cross section of electroforming equipment Sectional view showing the structure of the cathode Explanatory drawing which shows the method of immersing a cathode in the liquid tank of an electroforming device Graph showing current density pattern during electroforming Perspective view of main part of magnetic transfer device Plan view showing how to apply magnetic field for transfer Process diagram showing the basic steps of the magnetic transfer method

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Master disk (Master disk for magnetic transfer), 11 ... Master board | substrate, 12 ... Magnetic layer, 14 ... Slave disk, 20 ... Magnetic transfer apparatus, 60 ... Electroforming apparatus, 62 ... Plating liquid, 64 ... Plating tank, 66 ... Drain tank, 68 ... Ni pellet, 70 ... Anode chamber, 72 ... Cathode, 84 ... Cathode body, 86 ... Conductive ring, 88 ... Presser ring, 90 ... Shaft, D ... Dummy liquid, P ... Uneven pattern

Claims (4)

A master substrate which is a metal disk having a concavo-convex pattern corresponding to transfer information transferred on the surface by an electroforming process using an electroforming apparatus from an inverted mold having a reverse concavo-convex pattern is obtained, and a magnetic substrate is formed on the concavo-convex pattern of the master substrate. In the method of manufacturing a master disk for magnetic transfer in which a layer is formed,
Forming a conductive layer on the inversion-type surface;
Applying a dummy liquid to the surface of the inversion-type conductive layer and covering substantially the entire surface of the inversion pattern with the dummy liquid;
Immersing the inverted mold coated with the dummy liquid in a liquid tank of the electroforming apparatus;
A step of performing electroforming by taking electrical continuity between the reversal concavo-convex pattern of the reversing type immersed in a liquid tank of the electroforming apparatus and a cathode of a plating power source;
A method of manufacturing a master disk for magnetic transfer, comprising:   The method for manufacturing a master disk for magnetic transfer according to claim 1, wherein the dummy liquid is a liquid containing water as a main component.   3. The method for manufacturing a master disk for magnetic transfer according to claim 1, wherein the inversion-type inversion concavo-convex pattern is electrically connected to the cathode of the plating power source through a conductive ring in contact with the outer peripheral portion of the inversion concavo-convex pattern.   The method of manufacturing a master disk for magnetic transfer according to any one of claims 1 to 3, wherein the inversion type is a substrate having a conductive layer formed by sputtering on the surface of a silicon wafer.

Images