JP2002042334A - Magnetic transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability by preventing the occurrence of signal omission caused by an adhesion failure between a master carrier and a slave medium, in a magnetic transfer method for magnetically transferring an information signal, such as a servo signal, from the master carrier to the slave medium. SOLUTION: For magnetic transfer carried out by adhering a master carrier 3 carrying information to a slave medium 2, and applying a transfer magnetic field, before the application of the transfer magnetic field, a very small projection and an article struck on the surface of the slave medium 2 are removed by a grinding head 5 for the slave medium 2, and by increasing adhesion with the master carrier 3, signal omission is prevented. At the same time, by executing initial magnetization, process time is preferably shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic transfer method for magnetically transferring information from a master carrier carrying information to a slave medium.

[0002]

2. Description of the Related Art A magnetic transfer method transfers a magnetic pattern corresponding to information (for example, a servo signal) carried on a master carrier by applying a transfer magnetic field while the master carrier and the slave medium are in close contact with each other. It is. Examples of the magnetic transfer method include JP-A-63-183623, JP-A-10-40544, and JP-A-10-26.
No. 9566, and the like.

[0003]

By the way, at the time of the magnetic transfer by the above magnetic transfer method, if there are minute projections and deposits between the master carrier and the slave medium, a space is generated between the master carrier and the slave medium, and the magnetic transfer is performed. There is an area where no occurrence occurs. If magnetic transfer does not occur, signal missing occurs in the magnetic information transferred to the slave medium, and if the recorded signal is a servo signal, there is a problem that the tracking function cannot be sufficiently obtained and reliability is reduced. .

[0004] The minute projections causing the above-mentioned signal omission,
As a result of analyzing the attached matter, it was found that the surface of the slave medium was not flat and the protrusions originally possessed were dominant. Regarding deposits,
It has been found that the main cause is that dust and dust generated during the manufacturing process of the slave medium adhere to the surface.

The present invention has been made in view of the above problems, and has as its object to provide a magnetic transfer method capable of performing highly reliable magnetic transfer by preventing occurrence of signal omission in magnetic transfer. Things.

[0006]

According to the magnetic transfer method of the present invention, which solves the above-mentioned problems, a master carrier carrying an information signal and a slave medium are brought into close contact with each other to apply a transfer magnetic field to perform magnetic transfer. The transfer method is characterized in that before the transfer magnetic field is applied, minute protrusions and extraneous substances present on the slave medium surface are removed from the slave medium by a glide head in advance.

[0007] It is desirable that the glide head simultaneously performs initial magnetization of the slave medium while removing minute projections and deposits present on the surface of the slave medium.

In the magnetic transfer method for performing the initial magnetization of the slave medium, the slave medium is first DC-magnetized in the track direction, and a magnetic layer is formed in a fine uneven pattern corresponding to the slave medium and information to be transferred. The magnetic transfer is performed by applying a transfer magnetic field in a direction substantially opposite to the initial DC magnetization direction of the slave medium surface while keeping the master carrier for magnetic transfer in close contact. The information is preferably a servo signal.

[0009]

According to the present invention as described above, when a master carrier having transfer information and a slave medium are brought into close contact with each other and a transfer magnetic field is applied to perform magnetic transfer, the slave medium is preliminarily transferred to the glide head. By performing a process of removing minute projections and attached matter present on the surface, it is possible to prevent signal omission caused by poor adhesion between the master carrier and the slave medium due to the presence of the minute projections and attached matter, thereby improving quality. Stable magnetic transfer can be performed and reliability can be improved.

[0010] In addition, when the slave medium is initially magnetized by the glide head at the same time as the removal of minute projections and deposits on the surface of the slave medium, the process efficiency can be improved as compared with the case where the slave medium is processed in separate steps.

[0011]

Embodiments of the present invention will be described below in detail. FIG. 1 is a view showing a basic mode of a magnetic transfer method according to the present invention, in which (a) a step of applying a magnetic field in one direction to perform initial DC magnetization of a slave medium, and (b) a master carrier and a slave medium. (C) is a diagram showing a state after magnetic transfer, respectively, in a step of applying a magnetic field in the opposite direction by closely adhering. 2 and 3 are diagrams showing the pre-processing steps of the slave medium.

The outline of the magnetic transfer method is as follows. First, the slave medium 2 before being brought into close contact with the master carrier 3
As a pretreatment, as described later with reference to FIGS. 2 and 3, a glide treatment for removing minute projections and deposits on the surface is performed by a glide head 5, and simultaneously or subsequently to the glide treatment shown in FIG. As shown in a), an initial magnetic field Hin is applied to the slave medium 2 in one direction in the track direction to perform DC magnetization (DC demagnetization) in advance. Thereafter, as shown in FIG. 1B, the magnetic transfer surface of the slave medium 2 is brought into close contact with the information carrying surface of the master carrier 3 in which the magnetic layer 32 is coated on the fine uneven pattern of the substrate 31 so that the slave medium 2 The magnetic transfer is performed by applying a transfer magnetic field Hdu in the track direction 2 in a direction opposite to the initial magnetic field Hin. As a result, FIG.
As shown in (c), information corresponding to the pattern of the formation of the contact projections and recessed spaces of the magnetic layer 32 on the information carrying surface of the master carrier 3 is magnetically recorded on the magnetic transfer surface (track) of the slave medium 2. It is transcribed and recorded. For details of such a magnetic transfer method, see, for example, Japanese Patent Application No. 11-117800.
Please refer to the content described in the issue.

Incidentally, even when the concave / convex pattern of the substrate 31 of the master carrier 3 is a negative pattern having a concave / convex shape reverse to the positive pattern of FIG. 1, the direction of the initial magnetic field Hin and the direction of the transfer magnetic field Hdu are set as described above. By reversing the direction, similar information can be magnetically transferred and recorded.

When the substrate 31 is made of a ferromagnetic material such as Ni, magnetic transfer can be performed only with the substrate 31 and the magnetic layer 32 (soft magnetic layer) need not be covered. By providing the layer 32, better magnetic transfer can be performed. When the substrate 31 is a non-magnetic material, it is necessary to provide the magnetic layer 32.

When the magnetic layer 32 is coated on the substrate 31 made of a ferromagnetic metal, the influence of the magnetism of the substrate 31 is cut off.
It is preferable to provide a non-magnetic layer between the substrate 31 and the magnetic layer 32. Further, the uppermost layer is coated with a protective film such as diamond-like carbon (DLC), and this protective film improves contact durability and enables magnetic transfer many times. DLC
An Si film may be formed below the protective film by sputtering or the like.

When magnetic transfer is performed on both surfaces of the slave medium 2, a magnetic transfer is performed in a separate process for each side, and a master carrier 3 is adhered to both sides of the slave medium 2 to perform magnetic transfer simultaneously on both sides. There is a way.

The preprocessing of the slave medium 2 is shown in FIGS.
It will be described based on. As shown in FIGS. 2 and 3, the slave medium 2 is a disk-shaped magnetic recording medium (flexible disk) having a center core 21 (hub) fixed at the center, and a spindle (not shown) is connected to the center core 21. In addition, the glide heads 5 and 5 are brought into floating contact with the upper and lower surfaces thereof while being rotationally driven in the rotation direction D, and the glide heads 5 and 5 are moved in the radial direction S of the slave medium 2. As a result, a glide process is performed to remove minute projections and dust and other deposits on the surface of the slave medium 2 by contact with the glide heads 5 and 5.

The glide head 5 is vertically arranged so as to sandwich the slave medium 2, and has a head part 52 (slider) at the tip of a suspension 51.
Is urged by a spring urging force of the suspension 51 toward the surface of the slave medium 2 with a small force, and floats due to an air flow generated with the high-speed rotation of the slave medium 2 to maintain a minute gap (for example, about 20 nm). And confront each other. On the air bearing surface 53 (see FIG. 4) of the head portion 52 facing the slave medium 2, the tip side with respect to the rotation direction D of the slave medium 2 is formed as an inclined surface 53 a, and floats by air flowing from this portion.

The air bearing surface 53 of the head portion 52 of the glide head 5 is, for example, shown in FIGS.
It is provided in the form as shown in FIG. In the example of FIG. 4A, the air bearing surface 53 of the head portion 52 is formed of a hard material, and a blade formed by crossed oblique grooves 53b is engraved on the entire surface thereof. This is scraped off, and the attached matter is blown off or held in the groove 53b and removed from the medium surface. In the example of FIG. 4B, the cutting interval of the blade by the cross-shaped oblique groove 53b is wider than that of FIG.

In the example shown in FIG. 4C, a head core 54 having a head gap (erase gap) for initial magnetization is provided integrally with the glide head 5. Head part 5
2 are provided on both sides of the air bearing surface 53 with bearing portions 53c protruding in a rail shape.
3c has a levitation function and a function of removing the minute projections and attached matter. A head core 54 such as an inductive head for performing initial magnetization (DC demagnetization) is disposed on the rear end side. Note that a groove 53b as shown in (a) or (b) may be formed on the surface of the bearing portion 53c.

Next, the production of the magnetic transfer master carrier 3 will be described. As the substrate 31 of the master carrier 3, nickel, silicon, quartz plate, glass, aluminum, alloy, ceramics, synthetic resin, or the like is used. The formation of the concavo-convex pattern is performed by a stamper method, a photofabrication method, or the like.

In the stamper method, a photoresist is formed on a glass plate (or quartz plate) having a smooth surface by spin coating or the like, and a laser beam (or a laser beam) modulated according to a servo signal while rotating the glass plate is formed. An electron beam (electron beam) is applied to expose a predetermined pattern on the entire surface of the photoresist, for example, a pattern corresponding to a servo signal extending linearly in the radial direction from the center of rotation to each track on a portion corresponding to each frame on the circumference. Thereafter, the photoresist is developed and the exposed portions are removed to obtain a master having an uneven shape due to the photoresist. Next, based on the uneven pattern on the surface of the master, the surface is plated (electroformed) to form a Ni substrate having a positive uneven pattern, and the Ni substrate is separated from the master. This substrate is used as a master carrier as it is, or a non-magnetic layer, a soft magnetic layer, and a protective film are coated on the concavo-convex pattern as needed to obtain a master carrier.

Further, a plating is performed on the master to form a second master, and plating is performed using the second master.
A substrate having a negative concavo-convex pattern may be produced. Further, a second master may be plated or pressed with a resin solution and cured to form a third master, and the third master may be plated to form a substrate having a positive concavo-convex pattern. .

On the other hand, after forming a pattern with a photoresist on the glass plate, etching is performed to form a hole in the glass plate, a master disc from which the photoresist is removed is obtained, and a substrate is formed in the same manner as described above. You may.

As the material of the substrate made of metal, Ni or a Ni alloy can be used. The plating for forming this substrate is performed by various kinds of metal film formation including electroless plating, electroforming, sputtering, and ion plating. Law is applicable. Depth of uneven pattern on substrate (height of protrusion)
Is preferably in the range of 80 nm to 800 nm, more preferably 150 nm to 600 nm. This concavo-convex pattern is formed long in the radial direction in the case of a servo signal.
For example, the length in the radial direction is preferably from 0.3 to 20 μm, and the length in the circumferential direction is preferably from 0.2 to 5 μm. It is preferable to select a pattern that is longer in the radial direction in this range as a pattern carrying servo signal information. .

The magnetic layer (soft magnetic layer) is formed by depositing a magnetic material using a vacuum deposition method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a plating method. As the magnetic material of the magnetic layer, Co, a Co alloy (Co
Ni, CoNiZr, CoNbTaZr, etc.), Fe, F
e alloys (FeCo, FeCoNi, FeNiMo, Fe
AlSi, FeAl, FeTaN), Ni, and Ni alloy (NiFe) can be used. Particularly preferably, F
eCo and FeCoNi. The thickness of the magnetic layer is 50n
m to 500 nm, more preferably 1 to 500 nm.
It is 50 nm to 400 nm. The material of the nonmagnetic layer provided as an underlayer below the magnetic layer may be Cr, CrT
i, CoCr, CrTa, CrMo, NiAl, Ru,
C, Ti, Al, Mo, W, Ta, Nb and the like are used. This nonmagnetic layer can suppress deterioration of signal quality when the substrate is a ferromagnetic material.

Preferably, a protective film such as DLC is provided on the magnetic layer, and a lubricant layer may be provided. More preferably, a DLC film of 5 to 30 nm and a lubricant layer are present as a protective film. Further, an adhesion strengthening layer such as Si may be provided between the magnetic layer and the protective film. The lubricant is used to compensate for the displacement that occurs during the contact process with the slave medium.
Improves durability deterioration such as generation of scratches due to friction.

A resin substrate may be prepared using the master, and a magnetic layer may be provided on the surface of the resin substrate to form a master carrier. As a resin material for the resin substrate, an acrylic resin such as polycarbonate and polymethyl methacrylate, a vinyl chloride resin such as polyvinyl chloride and a vinyl chloride copolymer, an epoxy resin, an amorphous polyolefin, and a polyester can be used. Polycarbonate is preferred in terms of moisture resistance, dimensional stability, cost, and the like. If there are burrs on the molded product, they are removed by varnish or polish. The height of the pattern protrusion of the resin substrate is 50 to 10
The range of 00 nm is preferred, and more preferably 200 to
The range is 500 nm.

A master layer is obtained by coating a magnetic layer on the fine pattern on the surface of the resin substrate. The formation of the magnetic layer
The magnetic material is formed by a vacuum film forming method such as a vacuum evaporation method, a sputtering method, or an ion plating method, or a plating method.

On the other hand, in the photofabrication method, for example, a photoresist is applied to a smooth surface of a flat substrate, and exposure and development using a photomask corresponding to a servo signal pattern are performed. Form a pattern. Next, in the etching step, the substrate is etched according to the pattern, and a hole having a depth corresponding to the thickness of the magnetic layer is formed. Next, a vacuum deposition method of a magnetic material,
A magnetic material is formed to a thickness corresponding to the formed holes by a vacuum film forming means such as a sputtering method or an ion plating method or a plating method to the surface of the substrate. Next, the photoresist is removed by a lift-off method, and the surface is polished to remove any burrs and to smooth the surface.

Next, the slave medium 2 will be described. As the slave medium 2, a coating type magnetic recording medium or a metal thin film type magnetic recording medium is used. Commercially available media such as high-density flexible disks are examples of the coating type magnetic recording media. Regarding the metal thin film type magnetic recording medium, first, Co, a Co alloy (CoPtCr, CoC
r, CoPtCrTa, CoPtCrNbTa, CoC
rB, CoNi, etc.), Fe, Fe alloys (FeCo, Fe
Pt, FeCoNi) can be used. It is preferable that the magnetic flux density is large and that the magnetic recording medium has magnetic anisotropy in the same direction as the slave medium (in-plane direction for in-plane recording, perpendicular direction for perpendicular) because clear transfer can be performed. It is preferable to provide a non-magnetic underlayer under the magnetic material (on the side of the support) to provide the necessary magnetic anisotropy. It is necessary to match the crystal structure and lattice constant to the magnetic layer.
For this purpose, Cr, CrTi, CoCr, CrTa, C
rMo, NiAl, Ru or the like is used.

Examples 1 and 2 and Comparative Example 1 of the magnetic transfer method of the present invention are shown below, and the results of evaluating the characteristics are shown in Table 1.

Example 1 The magnetic transfer method of Example 1 uses a commercially available high-density flexible disk (Zip25
0), glide processing of the slave medium was performed as a preliminary processing using a glide head having an air bearing surface shown in FIG. The glide head is provided with an inductive head having a track width of 100 μm and a gap width of 0.4 μm for initial magnetization. The glide head removes minute protrusions and extraneous matter from the slave medium, and initializes the magnet (DC demagnetization).
Is given at the same time.

A master carrier was brought into close contact with the slave medium, and a transfer magnetic field was applied in a direction opposite to the initial magnetic field to perform magnetic transfer. The master carrier was produced by a stamper method. FeCo5 on a Ni substrate having an uneven pattern
A 0 at% magnetic layer was provided. The formed pattern is 5 μm wide from the center of the disk to a position of 20 mm to 40 mm in the radial direction.
Are provided at regular intervals, and the line interval is 1.5 μm at the innermost position in the radial direction of 20 mm. The magnetic layer was formed by a DC sputtering method using a 730H sputtering apparatus manufactured by Anelva, with a forming temperature of 25 ° C. and an Ar sputtering pressure of 1.
5 × 10 ⁻⁴ Pa (1.08 mTorr), input power is 2.
80 W / cm ² .

[Embodiment 2] In the magnetic transfer method according to Embodiment 2, glide processing is performed on the same slave medium as in Embodiment 1, and the initial magnetization is performed by using an electromagnet apparatus without using a magnetic head in a separate step. Was applied. Otherwise, magnetic transfer was performed using the same master carrier as in Example 1.

Comparative Example 1 In the magnetic transfer method of Comparative Example 1, the same master medium as in Example 1 was used without performing glide processing and initial magnetization on the same slave medium as in Example 1. To perform magnetic transfer.

In Table 1, as a method for evaluating "signal omission", a magnetic developer (Sigma High Chemical Co .; Sig Marker Q; diluted 10 times) was used to dilute the slave medium after magnetic transfer. Then, the amount of fluctuation of the magnetic transfer signal edge that was dropped, dried, and developed was evaluated. Servo signal section is 100 times with a differential interference microscope at 50 times magnification.
Observation of the field of view is performed, and the evaluation is evaluated as “O” if the signal loss is good at 5 or less places, and “X” if the value is not acceptable.

In order to evaluate the efficiency of the “process time”, the time required for the magnetic transfer of the second embodiment in the process of performing initial magnetization after the glide processing of the slave medium is reduced by one.
And the process time was expressed as a relative value.

As can be seen from the results in Table 1, in Example 1, the glide treatment and the initial magnetization were performed at the same time.
The process time is short and the number of missing signals is small, which is a good result. In the second embodiment, the glide process and the initial magnetization are performed in separate steps, so that the process time is longer than in the first embodiment, but the number of missing signals is small, which is a good result.
On the other hand, in Comparative Example 1, since both the glide treatment and the initial magnetization were not performed, the process time was short, but the number of missing signals was large and the transfer quality was inferior.

[0040]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a diagram showing a magnetic transfer method according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a glide processing state.

FIG. 3 is a front view of FIG. 2;

FIG. 4 is a diagram showing an example of a form of an air bearing surface of a glide head.

[Explanation of symbols]

 2 Slave medium 3 Master carrier 5 Glide head 31 Substrate 32 Magnetic layer 51 Head part 52 Suspension 53 Air bearing surface 53a Inclined surface 53b Groove 53c Bearing part 54 Head core

Claims (2)

[Claims] 1. A magnetic transfer method in which a master carrier carrying an information signal and a slave medium are brought into close contact with each other and a transfer magnetic field is applied to perform magnetic transfer. A magnetic transfer method comprising removing minute projections and extraneous matter present on the surface of the slave medium by using a glide head on the medium. 2. The magnetic transfer method according to claim 1, wherein initial magnetization of the slave medium is performed by the glide head at the same time as removing minute projections and extraneous matter present on the surface of the slave medium.