JP2006318572A - Magnetic disk and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a recording of contact information with a high productivity by a DC magnetization in a magnetic disk utilizing a (Discrete Track Recording) system having a separation groove between information areas. <P>SOLUTION: A section between data areas wherein the data are written, in the data information recording region of concentrically arranged magnetic recording tracks is separated by the separation groove 19, and the control information of a control information recording region is recorded as a recessed pit 23 having a predetermined depth with respect to a surface of a land section 24, and a magnetization facing opposed to a magnetization of the land section 24 is arranged by the DC magnetization so as to be formable on the recessed pit 23 by utilizing a level difference of the recessed pit from a surface of the land section 24 and a depth difference with the separation groove 19. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic disk and a manufacturing method thereof.

In order to realize a large capacity in a magnetic storage device, higher density is required.
A hard disk drive device, which is a typical magnetic storage device, has already been commercialized with a surface recording density exceeding 10 Gbit / inch ² .
FIG. 13 is a schematic cross-sectional view of a normal hard disk. In this hard disk, for example, a magnetic layer 2, a protective layer 3, and a lubricating layer 4 are sequentially formed on a substrate 1 having a flat surface made of an Al substrate on which a Ni layer is formed. An annular recording track is arranged in a flat continuous magnetic layer concentrically with the central hole 5 as the center, and the adjacent recording tracks are continuous without being physically independent. It is formed by a region.
Therefore, in such a hard disk, the density in the radial direction, that is, the track pitch affects the S / N of the reproduction signal.

In the case where the adjacent recording tracks are continuous in this way, considering the influence of the reproduction signal on the S / N, the track width of the magnetic gap of the recording magnetic head (hereinafter simply referred to as the recording magnetic head width) Ww It is necessary to select a width smaller than the track width W (Ww <W).
That is, the width of the recording mark recorded by the recording magnetic head is actually a width equal to or larger than the recording magnetic head width Ww due to the bleeding phenomenon due to the leakage magnetic field in the radial direction of the hard disk from the magnetic gap of the recording magnetic head. . For this reason, the width of the recording mark is composed of a portion formed by the recording head (a width equivalent to the recording head width) and a portion formed by a bleeding phenomenon, and the recording mark portion formed by this bleeding phenomenon. Therefore, an accurate reproduction signal cannot be obtained.
Therefore, if the recording magnetic head width Ww is made equal to the recording track width W, an extra signal is written to the adjacent recording track, and the recording mark formed on the adjacent recording track is eroded. Become.
When the recording mark is eroded as described above, the S / N of the reproduction signal deteriorates when the reproducing head detects the leakage magnetic field from the recording mark, that is, reproduces the recorded information data.
Therefore, it is necessary to select the magnetic head width Ww of the recording head smaller than the recording track width W (Ww <W) as described above.

On the other hand, in order to obtain a highly sensitive reproduction signal from the leakage magnetic field of the recording mark, it is necessary not to detect the leakage magnetic field from the portion formed by the above-mentioned blurring phenomenon during recording. It is necessary to make the reproducing head width Wr equal to or smaller than the width of the reproducing head. In particular, since the center of the recording track cannot always be traced due to the servo deviation during the reproducing operation, it is necessary to select the reproducing head width Wr in consideration of that amount.
However, if the width Wr of the reproducing head is reduced, the reproduced signal obtained is reduced, and the S / N is reduced. Therefore, it is desirable to make this width Wr as large as possible.

From the above, the relationship between the reproducing head width Wr, the recording magnetic head Ww, and the recording track width W is
Wr <Ww <W
Will be selected.
That is, it is impossible to form a recording mark using the entire recording track width W. On the other hand, not all of the formed recording marks can be reproduced.

Therefore, a technique called DTR (Discrete Track Recording) has been proposed as a technique for increasing the density of hard disks (see Non-Patent Document 1, for example).
According to the DTR, the above-described problem with respect to the pitch of the recording track can be reduced. Specifically, a physical separation groove is provided between adjacent recording tracks so that adjacent recording tracks are independently separated from each other so that a leakage magnetic field from the groove does not reach the reproducing head, that is, the reproducing head leaks. It is a hard disk formed so as to have a groove depth and groove shape that does not detect a magnetic field.

In a hard disk in which a separation groove is formed between adjacent recording tracks by this DTR, it is not necessary to consider the above-mentioned blurring phenomenon. Therefore, the recording magnetic head width Ww is larger than the land width between the separation grooves of the recording tracks. The recording mark width can be formed over the entire width of the land portion between the separation grooves.
At the same time, since there is no need to consider the above-mentioned blur phenomenon, the reproducing magnetic head width Wr can be made larger than the width over the entire width of the land portion between the separation grooves, that is, the land width. Therefore, even if there is a servo deviation, the entire width of the land portion can be reproduced.
In other words, in the DTR configuration, the width of the recording mark is limited to the land width, and the recording mark width can be increased, so that the S / N with respect to the track pitch can be increased.

On the other hand, in the hard disk, information such as servo signals and address signals recorded in advance is also recorded by S pole / N pole magnetic signals. Such information was written by a required writing device before the hard disk was incorporated into the set.
In a hard disk using a DTR, a recording track is formed as a convex portion when the disk is formed due to the presence of the separation groove, and therefore it is necessary to write servo information along the recording track.
As a method for writing this information, there has been proposed a method of writing a servo signal by magnetizing a repetitive signal on a hard disk using an external alternating magnetic field (see Patent Document 1).
IEEE TRANSACTION ON MAGNETICS, VOL.40, NO.4, JULY 2004 PP.2510-2515 Patent No. 2863190

However, when writing control information such as a servo signal by repetitive magnetization using such a write external alternating magnetic field, if the frequency of the external alternating magnetic field increases with increasing recording density, this alternating magnetic field generating means For example, it is necessary to increase the driving frequency of the electromagnet, and the steepness of inversion of the SN pole is reduced.
Further, the operation of writing the information signal for each recording track requires a long time, and there is a problem that the workability and, therefore, the productivity is inferior.
The work for obtaining the DTR configuration is also complicated.
The present invention provides a magnetic disk and a method for manufacturing the same that can easily and highly efficiently manufacture a magnetic disk having a DTR configuration.

  In the magnetic disk according to the present invention, a plurality of magnetic recording tracks in which a plurality of sectors each having a data information recording area and a control information recording area are arranged are concentrically arranged, and data in the data information recording area of each magnetic recording track is recorded. The data areas to be written are separated by a separation groove, and the control information in the control information recording area is recorded as concave pits having a depth different from that of the separation groove with respect to the data area surface. The concave pit and the land portion outside the separation groove forming portion are selected in opposite directions in the initialized state.

In the magnetic disk according to the present invention, the control information recording area includes a clock area to which a clock signal for phase signal detection is written, a servo area to which a servo signal is written, and an address to which address information or ID information is written. And the clock signal, servo signal, address information or ID information is recorded as the concave pit.
The depth of the separation groove is selected to be greater than the depth of the concave pit.

  A method of manufacturing a magnetic disk according to the present invention is a method of manufacturing a magnetic disk in which a plurality of magnetic recording tracks in which a plurality of sectors are formed by a data information recording area and a control information recording area are arranged concentrically. A separation groove forming step for forming a separation groove between data areas in which data is written in the data information recording area of each magnetic recording track, and the control information in the control information recording area is shallower than the separation groove. The step of forming a concave pit, the step of forming a reverse pit in the concave pit, the step of forming a concave pit, the land outside the separation groove and the formation of the concave pit, and the inside of the concave pit by applying a reverse DC magnetic field And a process.

The separation groove forming step includes a step of forming a resist layer having an opening corresponding to the pattern of the separation groove by photolithography, and the substrate surface or a material surface formed on the substrate surface through the opening of the resist layer. And an etching step for forming a separation groove having the required depth.
The step of forming the concave pit includes a step of forming a resist layer having an opening corresponding to the control information recording pattern by photolithography, and a material surface formed on the substrate surface or the substrate surface through the opening of the resist layer. And an etching step for forming a concave pit shallower than the separation groove,
The exposure in the photolithography in the separation groove forming step and the concave pit forming step is characterized by reduction projection exposure using an exposure mask formed by photolithography by pattern exposure with an electron beam or a laser beam.

As described above, the magnetic disk according to the present invention has a DTR configuration in which the data areas to which data is written in the data information recording area are separated by the separation grooves, and thus the mutual magnetic flux due to the leakage magnetic flux between the adjacent data areas. Erosion can be avoided. Therefore, the track width of the recording magnetic head can be made larger than the width of the data area, and the recording mark can be reliably formed over the entire width of the data area. In reproducing, the track width of the reproducing magnetic head can be selected to be larger than the data area width and therefore larger than the recording mark.
Thereby, the S / N of the reproduction signal can be increased.

  In particular, in the present invention, control information, specifically, clock signal, servo signal, address information or ID information, etc., is a direct current in the direction opposite to the land portion in the concave pit. Since it is recorded by magnetization, it is possible to record control information that can be reproduced with high S / N.

  In the method of manufacturing a magnetic disk according to the present invention, control information such as a clock signal, servo signal, address information or ID information is written to the magnetic disk on which the separation groove is formed by a DC magnetic field. Therefore, each information can be written easily and in a short time with high workability without using an electromagnet or a special overwrite head for writing by an alternating magnetic field.

  In addition, the formation of the separation grooves and the concave pits can be formed on a single wafer substrate by photolithography using a reduced projection exposure method using an exposure mask disk, so that a large number of magnetic disks can be formed on one wafer substrate. By performing a series of common photolithography processes, etching processes, film forming processes, and the like, a large number of magnetic disks can be manufactured simultaneously, and mass production can be achieved.

Embodiments of a magnetic disk and a manufacturing method thereof according to the present invention will be described. However, the present invention is not limited to this embodiment.
[Embodiment example of magnetic disk]
FIG. 1 is a schematic plan view of a hard disk as a magnetic disk according to the present invention. The magnetic disk 10 is formed on a disk substrate 11 made of, for example, Al, glass, Si or the like having a center hole 12 mounted on a magnetic disk drive device (not shown), with the center hole 12 as a center. A magnetic layer 13 is formed around the periphery, and a magnetic recording region portion 14 is formed.

A large number of magnetic recording tracks 15 (only one track is shown in FIG. 1) are concentrically arranged and formed around the center hole 12 in the magnetic recording region portion 14.
2 is a schematic plan view of the main part of the magnetic disk 10 of FIG. 1, and chain lines T1, T2, T3... Indicate the center lines of a part of the magnetic tracks 15 adjacent to each other arranged concentrically. .
FIG. 3 is a schematic sectional view taken along line AA in FIG.

Each magnetic recording track 15 has a configuration in which a plurality of sectors S by the control information recording area 17 are arranged in the data information recording area 16, and the data information recording area 16 is divided by the control information recording area 17.
A separation groove 19 having a required depth with respect to the upper surface of the data area 18 is formed between the data areas 18 in which information data is written in the data information recording area 16 of the adjacent magnetic recording track 15. The data area 18 is formed into a strip pattern by the groove 19.

The control information recording area 17 includes a clock area 20 in which a clock signal for phase signal detection is written, a servo area 21 in which servo signals for obtaining tracking servo control information during reproduction of information data are written, address information or ID. And an address area 22 in which information is written.
In each clocking area 20, servo area 21, and address area 22 of the control information recording area 17, a clock signal, servo signal, address information or ID information is recorded. These control information signals are formed by concave pits 23 having a predetermined depth with respect to the data area 18 surface, that is, the upper surface of the land portion 24, as shown in FIGS.

The magnetic layer 13 is formed at least in the concave pits 23 and on the concave pits 23 and on the land portions 24 outside the formation portions of the separation grooves 19. In FIG. 4, the magnetization of the control information signals is recorded and reproduced by the reversal of the magnetization at the edge of the concave pit 23 by the magnetizations opposite to each other.
That is, for example, as shown by a white arrow a in FIG. 2, when, for example, in-plane magnetization in one direction along the magnetic recording track direction is performed in the land portion, the control is performed by the reverse magnetization shown by the white arrow b. Information is recorded.

  As shown in FIG. 3, the depth of the separation groove 19 in the data information recording area 16 is selected sufficiently larger than the depth of the concave pit 23, and the data information on the land portion 24 separated by the separation groove 19 is The depth is set to prevent interference during writing and reading of this data information.

  In this way, in the magnetic recording area portion in which the magnetic layer 13 shown in FIG. 1 is formed, the data information in which each of the many concentric recording tracks 15 is intermittent with the control information recording area 17 as a blocking portion. The recording area 16 is composed of a plurality of sectors S.

In this configuration, the magnetic disk 10 is rotated so that the reproducing magnetic head runs on the magnetic track 15. At this time, the detected magnetic field is reversed at the edge position of the concave pit 23 by the magnetic head, so that the clock, servo, and address signal can be read out.
In this way, it is possible to read the data information in the data information area 18 by tracking the magnetic head with respect to the magnetic track 15 with high accuracy.

  Next, the above-described method for manufacturing a magnetic disk in which the concave and convex pits 23 and the separation grooves 19 having different depths are formed on the surface, and the land portion and the concave pits are magnetized in opposite directions is performed. The example of a form is shown.

[Embodiment example of manufacturing method of magnetic disk]
In the manufacturing method of the present invention, as described above, the magnetic disk 10 in which a plurality of magnetic recording tracks 15 in which a plurality of sectors S are formed by the data information recording area 16 and the control information recording area 17 are arranged concentrically. In manufacturing, a separation groove forming step for forming a separation groove 19 between data areas 18 in which data is written in the data information recording area 16 of each magnetic recording track 15, and control information in the control information recording area 17 in the separation groove 19. The concave pit forming step for forming the concave pit 23 with a shallower depth, the land portion 24 outside the formation portion of the separation groove 19 and the concave pit 23, and the magnetization in opposite directions in the concave pit 23, And a magnetization step performed by applying a reverse direct current magnetic field.

In the method for manufacturing a magnetic disk according to the present invention, the formation of the separation grooves 19 and the formation of the concave pits 23 are respectively formed by etching processes using photolithography.
In this case, a large-area wafer capable of producing a plurality of magnetic disks is prepared, and a plurality of magnetic disks are simultaneously produced, and then divided into a plurality of magnetic disks, thereby simultaneously producing a plurality of magnetic disks. A magnetic disk can be obtained.
Photolithography in the manufacture of this magnetic disk creates a first exposure mask disk for forming the concave pits 23 described above and a second exposure mask disk for forming the separation grooves 19, and uses them. The exposure for forming the concave pit and the deeper separation groove 19 is performed by a step exposure method using reduced projection exposure.

The first and second exposure mask disks are manufactured as exposure mask disks having a similar pattern, for example, four times or five times that of the magnetic disk substrate 11 in the final target magnetic disk 10, for example. To do.
FIG. 4 is a process diagram of a method for manufacturing these exposure mask disks. As shown in FIG. 4A, an exposure mask substrate 31 constituting an exposure mask disk made of, for example, a glass substrate or a quartz glass substrate is prepared, and its surface. A light shielding metal film 32 made of Cr, for example, and a resist layer 33 made of photoresist in this example of a positive type are applied thereon.
As shown in FIG. 4B, pattern exposure is performed on the resist layer 33.
Thereafter, by developing the resist layer 33, the exposed portion is removed and an opening 34 is formed in the positive photoresist layer.

  As shown in FIG. 4C, an exposure mask board 34 is produced in which a light shielding portion is formed by the light shielding metal layer 32 left by etching the light shielding metal layer 32 through the opening 34 of the resist layer 33.

  The resist layer 33 made of a photoresist in the production of the exposure mask board 34 can be performed by laser the beam scanning.

For the laser beam exposure, a so-called laser beam recorder (LBR) can be used as shown in the schematic block diagram of FIG.
The LBR includes, for example, a laser light source 41 that emits ultraviolet laser light such as an Ar laser having a wavelength of 351 nm and a YAG fourth harmonic laser having a wavelength of 266 nm, an acoustooptic modulator 42, a beam expander 43, and a numerical aperture (N .. A.) has an objective lens 44 of around 0.9.

On the other hand, the light shielding metal film 32 shown in FIG. 4A and the substrate 31 of the exposure mask board on which the photoresist layer 33 is formed are rotated at high speed by an air spindle or the like.
Then, a laser beam from the laser light source 41 is applied to the photoresist layer by an acousto-optic modulator 42 according to a target mask board pattern at a high speed. For a DTR disk in which a laser beam expanded to a diameter is condensed on the resist layer 33 by the objective lens 44, and the mask 31 substrate is slowly slid in the radial direction while being exposed concentrically at a constant track pitch. The exposure is performed with the enlarged pattern.

Thereafter, when the photoresist layer 33 is immersed in a dedicated developer, for example, in the case of a positive resist, the exposed portion is dissolved in the developer, and the opening 34 due to the enlarged pattern of the separation groove 19 or the concave pit 23 is obtained. Is formed as shown in FIG. 4B.
In this case, for example, if the laser light source 41 having a wavelength of 266 nm is used, a resolution with a track pitch of 400 nm, for example, a pattern of the separation groove 19 having a sufficient margin can be obtained.

  Then, using the resist layer 33 thus formed with the openings 34 as a mask, as shown in FIG. 4C, the light shielding metal film 32 such as a Cr film is etched, and then the resist layer 33 is removed. To do. Thus, the 1st and 2nd exposure mask board 34 is produced, respectively.

In addition, the resist layer 33 can be exposed by electron beam exposure instead of the laser beam exposure described above.
FIG. 6 is a schematic configuration diagram of an electron beam recorder (EBR) that performs electron beam exposure.
In this case, the resist layer 33 on the light shielding metal film 32 on the exposure mask substrate 31 is composed of an electron beam resist.
The EBR has an anti-vibration table 51, on which an arrangement part of an object to be irradiated with an electron beam, that is, an arrangement part of an exposure mask substrate 31 on which a light shielding metal film 32 and a resist layer 33 are coated is formed. Is done.
The arrangement portion of the exposure mask substrate 31 has a spindle 53 on the air slide 52 for rotating the exposure mask substrate 3 1 about its axis.
The air slide 52 can be slid in two axial directions orthogonal to each other in a plane orthogonal to the axis of the substrate 31.

An electron beam column 54 is arranged on the electron beam irradiation object, that is, on the arrangement portion of the exposure mask substrate 31.
The electron beam column 54 includes an electron gun 55, a condenser lens 56, a blanking electrode (beam modulation unit) 57, an aperture 58, a beam deflection electrode 59, a focus adjustment lens 90, an objective lens 91, and the like. It consists of

With this configuration, the electron beam generated from the electron gun 55 is turned on and off at a high speed by the blanking electrode 57 and the aperture 58.
The electron beam 92 is converged to a diameter of 100 nm or less by the objective lens 91, converged on the electron beam resist on the exposure mask substrate 31, rotated by the spindle 53, and moved in the radial direction by the air slide 52. By exposing the resist layer 33 to the electron beam pattern, electron beam exposure is performed with a required pattern.
The resist layer 33 subjected to pattern exposure in this way is developed as described above to form an opening 34 as shown in FIG. 4B, and the light-shielding metal film 32 is etched through this opening 34, as shown in FIG. 4C. Thus, the mask board 35 for exposure is produced.
The hard disk according to the present invention is manufactured using the mask disk with the DTR pattern manufactured as described above.

7 and 8 are manufacturing process diagrams of an embodiment of the method of manufacturing the hard disk, that is, the magnetic disk.
First, as shown in FIG. 7A, a large-area substrate 61 made of glass, Si, Al or the like on which a surface material layer 92 of, for example, a NiP layer having a diameter of 300 mm, for example, is obtained. Then, a photoresist layer 63 is formed on the surface material layer 62 by coating.
The photoresist layer 63 is subjected to reduced projection exposure on the substrate 61 using, for example, a first exposure master having an exposure pattern of concave pits, thereby performing exposure on a plurality of disks.

FIG. 9 is a schematic block diagram of a stepper type reduced projection exposure apparatus that performs this reduced projection exposure.
In this case, a reduction projection having a light emitting unit 71, a light irradiation unit 72, an arrangement portion of the exposure mask board 35, and an objective lens (not shown) for reducing the exposure pattern of the exposure mask board 35 to 1/4. The unit 73 and the substrate 61 shown in FIG. 7A are placed, and the optical axis direction Z and an XYZ drive stage 74 that moves in the X and Y directions orthogonal to each other in a plane orthogonal to the optical axis direction Z are provided.

By this reduced projection exposure apparatus, an exposure process is performed on the photoresist layer 63 on the substrate 61 with a pattern obtained by reducing the exposure pattern of the exposure mask board 35.
In this exposure, step exposure is performed by step-moving the substrate 61 in the X and Y directions by the XYZ drive stage 74 to the portions that finally constitute a plurality of magnetic disks.
In this way, a plurality of pattern exposure processing portions 75 are formed in the photoresist layer 63 of the substrate 61 as shown in FIG.

In the reduced projection exposure described above, for example, a first exposure mask disk having an exposure pattern for finally obtaining the above-described concave pits 23 is used as the exposure mask disk 35.
Thereafter, as shown in FIG. 7B, development processing of the photoresist layer 63 is performed, for example, an opening 63W is formed in the pattern exposure portion, and dry etching is performed on the material layer 62 through the opening 63W as shown in FIG. 7C. The concave pit 23, that is, a control information recording portion is formed.

Thereafter, as shown in FIG. 7D, the photoresist layer is temporarily removed, the surface is cleaned, and the photoresist layer 63 is again applied over the entire surface.
The reduced projection exposure described above for the photoresist layer 63 uses a second exposure mask disk having an exposure pattern for finally obtaining the separation grooves 19 described above.
In this case, the exposure process using the second mask disk is performed in a state where the exposure process for the photoresist layer is aligned with the pattern position of the previously formed concave pit by the reduction projection exposure apparatus described with reference to FIGS. Do.
For this alignment, for example, a position mark is formed on the first mask disk, and a concave marker for alignment is formed along with the formation of the concave pit 23, so that the second exposure mask disk is based on this marker. Can be aligned.

As shown in FIG. 8A, development processing is performed to form an opening 63WG having a pattern of the separation groove 19.
As shown in FIG. 8B, the material layer 62 is dry-etched through the opening 63WG of the photoresist layer 63 to form the separation groove 19.
In this way, the separation groove 19 having a required depth with respect to the concave pit 23 and the land portion 24 outside the separation groove 19 is formed as compared with the depth of the concave pit 23.
As shown in FIG. 8C, the photoresist layer is removed, and the magnetic layer 13 includes at least the land portion 24 and the concave pit 23 on the surface where the land portion, the concave pit, and the separation groove are formed. Form.

  The light emitting unit 71 in the above-described reduction projection exposure apparatus is, for example, an exposure source using an ArF excimer laser with a wavelength of 193 nm, and the objective lens of the reduction projection unit 73 has a numerical aperture (NA) of 0.92 and an exposure range. Use a stepper of 26 mm × 33 mm. In this case, since the resolution was 65 nm or less, a separation groove with a track pitch of 130 nm could be easily formed.

In this case, since the exposure range covers a circle having a diameter of 1 inch (25.4 mm), pattern exposure of a DTR hard disk having a diameter of 1 inch is possible.
As described above, the magnetic disk substrate uses, for example, the wafer substrate 61 having a diameter of 300 mm, on which the NiP layer is formed as the surface material layer 62, and the photosensitive photoresist layer 63 is applied on the wafer substrate 61. As described above, the DTR pattern exposure process corresponding to as many 1 inch as possible on the substrate is carried out by being mounted on the XYZ stage 74 and stepped in the XY directions and repeatedly exposed at each position. 75 is formed.
For example, about 20 1 inch diameter patterns can be exposed on one substrate having a radius of 300 mm.

The etching for forming the concave pits and separation grooves for the NiP material layer described above uses, for example, a mixed gas of chlorine-based gas (Cl ₂ , SiCl _4, etc.) and oxygen (O ₂ ), and the etching rate depends on the flow rate ratio Adjustments can be made.
The concave pit 23 can be set to a depth of 30 nm, for example, and the depth of the separation groove 19 can be set to 60 nm, for example.

Next, as shown in FIG. 8D, the photoresist layer 63 is removed, and the magnetic layer 13 made of Co, Cr, Pt or the like is formed over the entire substrate 61 on which the concave / convex pattern is formed by the concave pits 23 and the separation grooves 19. Although not shown in the figure, a protective layer such as DLC (Diamond Like Carbon) and a lubricant layer are sequentially stacked on the substrate to obtain a plurality of magnetic disk forming substrates.
Thereafter, a plurality of, for example, 1 inch size hard disks with a DTR pattern, that is, a plurality of magnetic disks 10 according to the present invention are obtained simultaneously from the substrate 64 by laser processing or the like.

Thus, the magnetization process for initialization is performed on the magnetic disk 10 formed in large numbers, that is, the hard disk.
This magnetization process is performed by the first and second direct current magnetizations.
This magnetization can be performed by a floating type DC magnetic field writing head 80 as shown in FIG. 11, for example. In this case, the magnetic disk 10 is mounted on a turntable (not shown) and rotated at, for example, 3,600 rpm, and the magnetic layer 13 is applied to the magnetic layer 13 by the flying force due to the change in air pressure due to the rotation of the rotating magnetic disk 10. On the other hand, the magnetic head is arranged so as to maintain a predetermined interval, and the magnetic layer 13 is magnetized in, for example, the rotation direction with a DC magnetic field having a required strength by the electromagnetic induction magnetic head energized by the power supply 81.

The write head 80 using a direct current magnetic field has, for example, a write width of about 1 mm, and a slide on which the head is mounted moves in the radial direction of the disk.
The flying height is, for example, about 50 nm, and a magnetic field in a single direction is generated along the circumferential direction, that is, along the magnetic track, and the land portion 24, the concave pit portion 23, and The inside of the separation groove 19 is magnetized in one direction.
In this way, the first magnetization process is performed. In the first magnetization process, the separation groove 19 having the longest distance from the head does not necessarily have to be magnetized, but the land portion 24 and the concave pit 23 are subjected to DC magnetization in the same direction. So that

  Subsequently, a second magnetization process is performed. This second magnetization process is performed by applying a DC magnetic field in the direction opposite to the magnetization in the first magnetization process described above. This second magnetization process can also be performed by the same write magnetic head 80 as in the first magnetization process. In this case, by adjusting the flying height or the strength of the magnetic field, only the land portion 24 is reversed in magnetization so that the magnetization direction of the magnetization direction by the first magnetization process is maintained in the concave pit 23. .

  As described above, in the land portion 24 and the concave pit 23 by the magnetization process using the first and second DC magnetic fields, the magnetizations in the opposite directions indicated by the arrows a and b are shown in FIG. That is, a state in which the magnetization direction is reversed is formed.

  Thus, the edge of the concave pit 23 is formed by scanning the magnetic disk 10 on which the control information is recorded by the concave pit 23 and its magnetization with the reading magnetic head (not shown) on the disk 10. By detecting the signal corresponding to the magnetization reversal, the clock signal, tracking signal, and address signal are detected, and recording and reproduction of the signal in the data information recording area is performed in the same manner as a hard disk having no conventional DTR structure. Is something that can be done.

The magnetization over the entire recording area in the first magnetization process is performed in the same direction in a short time by applying a DC magnetic field entirely using a powerful and large-area electromagnet without using a magnetic head scanning. Magnetization can also be performed.
In addition, by setting the depth of the separation groove 19 sufficiently large, even if the magnetization by the first magnetization process is insufficient, or even in the random orientation state where the magnetization is not performed, The influence of the leakage magnetic field from the bottom of the separation groove in signal recording / reproduction can be ignored.

According to the magnetic disk manufacturing method described above, when a 1-inch size hard disk is manufactured with a track pitch of 130 nm, the recording capacity is calculated. When the TPI (Track per Inch) is 195 Kbit / inch, the BPI ( Bit per inch)
Is 7 times that of 1.37 Mbit / inch, and the surface density is about 200 Gbit / inch2. Since a 1-inch disk has an effective area of 0.46 inch ² , if the efficiency is estimated at 80% in consideration of areas such as servo and address pits, a single disk 10 has a recording capacity of about 12 GB on one side. Become.

As described above, in the present invention, the servo information can be written in a short time by enabling the writing with the external DC magnetic field without using the external alternating magnetic field as in the past, regardless of the DTR configuration. As a result, productivity can be significantly improved as compared with the prior art.
In addition, by applying a photolithography process using a reduced projection exposure method, a large number of, for example, 1 inch size small diameter magnetic disks having a diameter of 1.3 inches or less are mass-produced from a wafer substrate having a diameter of 200 mm to 300 mm. In particular, a small-sized hard disk for mobile use can be mass-produced.

The above-described magnetic disk structure as a magnetic disk and the initialization method are longitudinal magnetic recording methods in which magnetic recording is magnetized in a direction parallel to the disk surface, but the magnetization direction is recorded in a direction perpendicular to the disk surface. The same pattern structure, manufacturing process, and initialization method can be applied to the perpendicular magnetic recording method.
The present invention is not limited to the above-described embodiments described with reference to the drawings, and various modifications, substitutions or equivalents thereof can be made without departing from the scope and spirit of the appended claims. It goes without saying that it can be done.

It is a schematic plan view of an example of the magnetic disk of the present invention. It is a typical pattern figure of the principal part of an example of the magnetic disk of this invention. It is a schematic sectional drawing of the AA line of FIG. FIGS. 4A to 4C are process diagrams of an example of a method for producing a mask disk used in the method for producing a magnetic disk according to the present invention. It is a block diagram of an example of the laser beam exposure apparatus used for the manufacturing method of the magnetic disc by this invention. It is a block diagram of an example of the electron beam exposure apparatus used for the manufacturing method of the magnetic disc by this invention. A to D are process diagrams of the first half of an example of a method of manufacturing a magnetic disk according to the present invention. A to D are process charts in the latter half of an example of the method of manufacturing a magnetic disk according to the present invention. It is a block diagram of an example of the reduction exposure apparatus in the manufacturing method of the magnetic disc by this invention. It is explanatory drawing of the exposure state of reduction exposure. It is explanatory drawing of the initialization magnetization of the magnetic disc by this invention. It is a perspective view of the principal part cross section which shows the initialization magnetization state of the magnetic disc by this invention. It is a schematic sectional drawing of a part of conventional hard disk.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Magnetic layer, 3 ... Protective layer, 4 ... Lubrication layer, 5 ... Center hole, 11 ... Disk substrate, 12 ... Center hole, 13 ... Magnetic layer, 14 ... Recording area, 15... Magnetic track, 16... Data information recording area, 17... Control information recording area, 18... Data area, 19. , 22 address area, 23 ... concave pit, 24 ... land portion, 31 ... substrate 32 of exposure mask board, light shielding metal film, 33 ... photoresist layer, 34 ... exposure mask board, 41 ... Laser light source, 42 …… Acousto-optic modulator, 43 …… Beam expander, 44 …… Objective lens, 51 …… Shake-off table, 52 …… Air slide, 53 …… Spindle, 54 …… Electron beam column, 55… ... electronic 56 …… Condenser lens, 57 …… Blanking electrode (beam modulation part), 58 …… Aperture, 59 …… Beam deflection electrode, 61 …… Substrate, 62 …… Surface material layer, 63 …… Photoresist layer, 64... Magnetic disk forming substrate, 71... Light emitting unit, 72... Light irradiation unit, 73... Reduction projection unit, 74. 81 ... Power supply, 90 ... Focus adjustment lens, 91 ... Objective lens, 92 ... Electron beam

Claims (9)

A plurality of magnetic recording tracks in which a plurality of sectors by a data information recording area and a control information recording area are arranged are concentrically arranged,
The data areas in which data is written in the data information recording area of each magnetic recording track are separated by a separation groove,
Control information of the control information recording area is recorded as a concave pit having a depth different from the separation groove with respect to the data area surface,
A magnetic disk, wherein the concave pit and the land portion outside the formation portion of the concave pit and the separation groove are selected in opposite directions in an initialized state.   The control information recording area has a clock area in which a clock signal for detecting a phase signal is written, a servo area in which a servo signal is written, and an address area in which address information or ID information is written. 2. The magnetic disk according to claim 1, wherein a signal, address information or ID information is recorded as the concave pit.   2. The magnetic disk according to claim 1, wherein the depth of the separation groove is selected to be greater than the depth of the concave pit. A method of manufacturing a magnetic disk in which a plurality of magnetic recording tracks in which a plurality of sectors are formed by a data information recording area and a control information recording area are arranged concentrically,
A separation groove forming step for forming a separation groove between data areas in which data is written in the data information recording area of each magnetic recording track;
A concave pit forming step for forming the control information in the control information recording area as a concave pit having a shallower depth than the separation groove;
A magnetic disk comprising: a magnetizing step for performing reverse magnetization in a land portion outside the separation groove and the concave pit formation portion and in the concave pit by applying a direct current DC magnetic field in a reverse direction. Production method.   The control information recording area has a clock area in which a clock signal for detecting a phase signal is written, a servo area in which a servo signal is written, and an address area in which address information or ID information is written. 5. The method of manufacturing a magnetic disk according to claim 4, wherein a signal, address information or ID information is recorded as the concave pit. The separation groove forming step includes a step of forming a resist layer having an opening corresponding to the pattern of the separation groove by photolithography, and the substrate surface or a material surface formed on the substrate surface through the opening of the resist layer. And an etching step for forming a separation groove having the required depth.
The step of forming the concave pit includes a step of forming a resist layer having an opening corresponding to the control information recording pattern by photolithography, and a material surface formed on the substrate surface or the substrate surface through the opening of the resist layer. And an etching step for forming a concave pit shallower than the separation groove,
The exposure in the photolithography in the separation groove forming step and the concave pit forming step is reduced projection exposure using an exposure mask disk formed by photolithography by pattern exposure with an electron beam or a laser beam. 5. A method for manufacturing a magnetic disk according to 4.   5. The method of manufacturing a magnetic disk according to claim 4, wherein a magnetic layer is formed on the substrate surface on which the separation grooves and the concave pits are formed or a material surface formed on the substrate surface. The magnetic layer includes at least all the sectors in one direction in the same direction along the magnetic track direction including the land portion where the separation groove and the concave pit are not formed and the inside of the concave pit. First, a first magnetization processing step for magnetizing with a DC magnetic field,
Performing a second magnetization processing step of reversing the magnetization of the land portion with a magnetic field intensity that does not reverse the magnetization in the concave pit by a DC magnetic field in a direction opposite to the magnetization direction. The method for manufacturing a magnetic disk according to claim 4.   The selection of the magnetic field in the first and second magnetization processing steps is performed by selecting the magnetic field generation intensity of the magnetic field generation means for performing the respective magnetization or the distance between the magnetic field generation means and the substrate. The method for manufacturing a magnetic disk according to claim 8.

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