JP2003228828A - Method for manufacturing magnetic disk transfer master disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for patterning a photomask which is hardly affected by errors of stage movement even when the real amount of stage movement for scanning the photomask has errors with respect to the set amount of movement. <P>SOLUTION: In manufacturing a master disk used for transferring a magnetic pattern to a magnetic storage medium, a pattern for exposing a resist on an Si substrate which is a master disk substrate is constituted of a plurality of photomasks, and each photomask pattern is constituted of a sector unit. The pattern of each photomask is divided by a sector unit in the θ direction with respect to the center of the master disk, and by a circular arc having the center of the master disk as its origin in the R direction. Since a servo pattern present in one photomask is set by a sector unit, even when the photomask is shifted in position, its influence is hardly felt. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a magnetic disk transfer device for magnetically writing a positioning servo signal or specific data for a magnetic head for writing / reading on the surface of a magnetic disk by using a transfer technique. The present invention relates to a method for manufacturing a magnetic disk transfer master disk (hereinafter abbreviated as a master disk) in which a positioning servo signal or specific data is embedded as a pattern.

[0002]

2. Description of the Related Art Recently, in a hard disk drive which uses a magnetic film as a recording material, which has become a mainstream as an external storage device of a computer, a magnetic recording medium (hereinafter abbreviated as a medium) rotating on the surface of Data is recorded / reproduced while the head is flying at a distance of several tens of nm by a flying mechanism called a slider. The bit information on the medium is stored in concentric data tracks, and the data recording / reproducing head moves and positions at the target data track on the medium at high speed to record / reproduce data. Is going.

A positioning signal (servo signal) for detecting the relative position between the head and the data track is preliminarily written in a concentric pattern on the medium surface, and the head for recording / reproducing data is constant. It detects its position at time intervals. After incorporating the medium in the hard disk drive so that the center of the servo signal does not decenter from the center of the disk (or the center of the head track), the servo signal is written on the medium using a special device called a servo writer. There is.

At present, in this type of magnetic disk, the recording density reaches 60 Gb / in ² at the development stage, and the recording density increases at a rate of 100% or more per year. Along with this, the density of the servo signal for the head to detect its own position is also increasing, and the writing time of the servo signal tends to increase year by year. This increase in the writing time of the servo signal has become one of the major factors leading to a decrease in the productivity of the hard disk device and an increase in the cost. Recently, compared to the method of writing servo signals using the signal writing head of the servo writer described above, the servo signals are collectively written to the medium by magnetic transfer, and the servo information writing time is dramatically increased. Technology is being developed to reduce

7 and 8 are diagrams for explaining this magnetic transfer technique. FIG. 7A shows a state in which the permanent magnets move on the surface of the medium 701 while maintaining a constant interval (1 mm or less). The magnetic layer formed on the medium 701 is not initially magnetized in a fixed direction, but is magnetized in a fixed direction by the magnetic field leaked from the gap on the right side of the permanent magnetism. The arrow on the magnetic layer in the figure indicates the direction of magnetization. This process is called the initial degaussing process.

FIG. 8A is a sectional view showing the initial demagnetization process. The medium 701 includes a substrate 801 and a magnetic layer 80.
2 and the direction of magnetization of the magnetic layer 802 is
The direction is opposite to the traveling direction of 03 (relative movement direction).

FIG. 7B shows a state in which the magnetic transfer master disk 702 is placed on the medium 701 and aligned after the initial demagnetization step.

In FIG. 7C, after the alignment, the master disk 702 is brought into close contact with the surface of the medium 701, and the permanent magnet for magnetic transfer is moved along the moving path (shown by an arrow) in the drawing. By doing so, the magnetic transfer is performed.

FIG. 8B is a sectional view showing the magnetic transfer pattern writing process. The master disk 702 is provided on the surface side in contact with the surface of the silicon substrate 804,
As shown in the figure, soft magnetic film (Co-based soft magnetic film in the figure)
805 has an embedded structure.

The permanent magnet 803 and the magnetic layer 80 of the medium 701.
When a master disk 702 having a pattern of a soft magnetic film 805 embedded therein is inserted between the two, a magnetic field leaking from the permanent magnet 803 and transmitted to the silicon substrate 804 (the direction of the magnetic field for writing the transfer signal is The direction opposite to the degaussing magnetic field) allows the magnetic layer 802 to be magnetized by penetrating silicon again at the position where the soft magnetic film 805 does not exist, but at the portion where the pattern of the soft magnetic film 805 exists, the magnetic layer having a small magnetic resistance It passes through the soft magnetic film 805 so as to form a path. Therefore, at the position where the soft magnetic layer 805 exists, the magnetic field leaking from the silicon substrate 804 becomes small, and new writing of magnetization is not performed. The magnetic transfer of the servo signal is performed on the medium 701 by the mechanism as described above.

FIG. 9 illustrates the step of embedding the soft foundation layer 805 in the master disk 702. First step (resist pattern forming step of FIG. 9A): A resist (thickness 1 μm) is applied to the surface of a silicon substrate 804 (thickness: approximately 500 μm) by using a spin coater, and then the resist is usually applied. Patterning is performed by using the same optical lithography method as the manufacturing method of the silicon semiconductor described above. Second step (silicon substrate etching step of FIG. 9 (b)): The silicon substrate 804 is approximately 500 by using a reactive plasma etching method (reactive gas: methane trichloride).
nm dry etching is performed. Third step ((c) Co sputtering step of FIG. 9): Co is used by a sputtering method while leaving the resist.
A soft magnetic film is formed to a thickness of 500 nm. Fourth step (lift-off step in (d) of FIG. 9): After the Co soft magnetic film is formed, the silicon substrate is immersed in a solvent that dissolves the resist (using ultrasonic waves and the like as necessary), and C
o The resist between the soft magnetic film 805 and the silicon substrate 804 is dissolved and removed.

FIG. 10 shows a pattern of the soft magnetic film 805 embedded in the 3.5-inch master disk 702. FIG. 10A shows the entire size, and FIG.
Is a partial enlargement so that the embedded size can be seen.

The width of the pattern of the soft magnetic film 805 is 0.52 to 0.65 μm on the inner circumference and 0.98 to 1.4 on the outer circumference.
The size is 9 μm, which is close to submicron, and the patterning on the silicon substrate 804 requires accuracy of about 1/10 to 1/20 of this size.

[0014]

The above-mentioned silicon substrate 8 is used.
For the patterning to 04, an optical lithography method similar to the method for manufacturing a normal silicon semiconductor is used, but there are two types of methods, a direct drawing method and a photomask method.

1) Direct drawing method As shown in FIG. 11, a laser beam from a laser oscillation tube 1101 is reflected by a reflecting mirror 1102, an acousto-optic reflector (X direction) 1103, and an acousto-optic reflector (Y direction) 1.
By irradiating the resist surface 1105 on the silicon substrate 1106 through 104, patterning is performed on the silicon substrate 1106 (corresponding to the above silicon substrate 804).

By narrowing the laser beam from the laser oscillation tube 1101 with an optical system (not shown),
A beam with a small diameter is created, and the laser beam is scanned with an AOD (acousto-optic deflector) to produce Si.
Irradiation is performed on the resist surface 1105 applied to the substrate 1106. Actually, since it is necessary to scan in the X and Y directions,
Two sets of AOD are required: an acousto-optic reflector 1103 for X-direction scanning and an acousto-optic reflector 1104 for Y-direction scanning. The features and problems of this direct drawing method are described below.

Features-Because no mechanism is used in the laser beam scanning system,
If the temperature of the AOD crystal is controlled, a positional accuracy of about 25 nm can be obtained. -The drawing range is wide and a maximum of about 400 mm is possible.

Problem: It is necessary to draw a pattern for each master disk, and the manufacturing cost is high. The minimum beam diameter is about 0.8 μm, which does not satisfy the resolution required for a pattern with high recording density.

2) Photomask method As shown in FIG. 12 (a), after applying a resist to a glass plate on which a Cr film is formed, FIG. 12 (b),
As shown in (c), the resist is patterned by a drawing device (a device equivalent to the above-mentioned direct drawing device), and as shown in FIG.
By removing the Cr film in the exposed portion and removing the resist layer as shown in FIG. 12 (e), a photomask in which the Cr film in the unexposed portion is formed on the glass plate is obtained.

Generally, in the case of a submicron pattern, a photomask is prepared at a scale of 5 times the original size in consideration of the line width of a drawing device at the time of making the photomask and dust at the photoprocess, and then the Si substrate is formed. At the time of patterning, as shown in FIG. 13, an optical system having a reduction magnification of 1/5 is constructed. The size of the photomask 1301 is 5 inches,
Assuming that an optical system 1302 having a reduction ratio of 1/5 is used (note that 1106 is a Si substrate), 44 photomasks are used to form a 3.5-inch medium, as shown in FIG. It is necessary to connect the patterns.
The features and problems of this photomask method are described below.

Features-If a photomask is created, the steps including patterning are equivalent to the steps for creating an IC, so that the master disk manufacturing time is short and the manufacturing cost is low. -Since a reduction optical system is used, a submicron line width can be easily created, and it can be applied to high density media.

Problem: Since the patterns formed by the photomasks are connected to each other as described above, the positioning error of the mask is directly connected to the pattern shift of the connecting portion, and the servo signal cannot be obtained at an accurate position. .

The present invention has been made in view of the above problems, and an object thereof is that in the photomask system, the stage for scanning the photomask has an error in the actual movement amount with respect to the set movement amount. However, it is still another object of the present invention to provide a method for manufacturing a master disk for magnetic disk transfer by patterning a photomask that is less susceptible to the error.

[0024]

In order to achieve the above object, the present invention is to expose a resist on a Si substrate, which is a substrate of a master disk, in manufacturing a master disk used for transferring a magnetic pattern to a magnetic storage medium. The pattern to be formed is composed of a plurality of photomasks, and the pattern of each of the photomasks is composed in sector units.

Further, according to the present invention, the pattern of each photomask is θ with respect to the center of the master disk.
It can be characterized in that the direction is a sector unit and the R direction is delimited by an arc having the center of the master disk as an origin.

A master disk for magnetic disk transfer manufactured by using the above photomask according to the present invention is within the scope of the present invention.

The servo pattern (magnetic pattern) on the circumference of the magnetic storage medium is composed of several hundred and ten sectors,
Positioning control of magnetic head, reading and writing of data are all
It is completed in one sector. Therefore, as in the present invention, by making the servo pattern existing on one photomask be a sector unit, even if the photomask is displaced, it is possible to make it less susceptible to the effect. Also,
When the size of the magnetic storage medium is large and one sector cannot fit in the I photomasks, the sector is divided into the circumferential direction and the radial direction to divide into a plurality of photomasks. Can deal with it.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the arrangement of sectors in the magnetic storage medium according to the present invention. This sector has one index sector No-1 indicating the absolute position and N other sectors.
It is composed of 127 non-index sectors denoted by o-2 to No-128.

Each of the index sector and the non-index sector is composed of a region as shown in FIG. 2, and the main one is the VCO (Volt) of the circuit section.
A clock control area 201 of a pattern for generating a reference signal of an age control oscillator, an address area 204 of a pattern for detecting the position of the magnetic head, and a position detect (Position Dete).
ct) Region 205 is included. The clock area 201 is about 4
It is composed of zero magnetic patterns with 50% duty, and when the medium 701 rotates at a constant speed of 7200 rpm, a signal of about 5 MHz is obtained from the clock region 201 as the output of the magnetic head. .

Based on the signal obtained when passing through the clock region 201, the output clock of the VCO inside the circuit is synchronously controlled to generate the clock signal inside the circuit that matches the rotation speed of the medium 701. After passing through the clock domain 201, the VCO is locked and the clock domain 201 is locked.
The clock signal when the synchronization with the signal from is obtained.

Here, as shown in FIG.
In the detect area 205, staggered rectangular patterns (pattern X, pattern Y, pattern A, pattern B) are arranged on the servo track. Therefore, as shown in FIG. 4, the magnetic head 301 reads out the pattern signal of the position / detect region 205, the read signal is amplified by the amplifier 302, and then the low-pass filter 303 is passed through the full-wave rectifier 304. The output waveform is full-wave rectified and then integrated by the integrator 305.

The resulting signal is sampled by the sample and hold device 306, and X, X + Y, A,
Each signal of A + B is extracted, and X-
Calculate the Y, AB values. By doing so, a linear analog signal is obtained over the entire area of one track width, the amount of displacement from the track center is detected, and position correction is performed according to the detected amount to set the head position on the regular servo track. Can be controlled.

As described above, in each sector of the magnetic storage medium, the position of the magnetic head is detected, the position control is performed, and then a series of operations for reading and writing data is performed. For this reason, if magnetic pattern discontinuity occurs in each sector due to the seam of the photomask, there occurs a symptom that the reading and writing of data by the recording head is not normally performed. This is because if the deviation of the pattern in one sector in the θ direction changes, for example, the pattern interval of the clock region 201 changes in the middle, the frequency of the reference clock shifts, and the accuracy of the head position detection in the subsequent stage. ， It will greatly affect the approval of the data area.

Therefore, if the photomasks are connected so that the magnetic patterns are not shifted in each sector unit, that is, if the photomask for forming the master disk is prepared in sector units, the exposure position of the photomask is small. Even if the shift occurs, the shift does not occur on a sector-by-sector basis, so that there is no problem in detecting the position of the magnetic head, reading and writing data.

FIG. 5 shows an example of application of the present invention to a 1-inch storage medium. Since the outer diameter of a 1-inch storage medium is 22 mm, the effective exposure area on a Si wafer is 15 mm square when 1/5 reduction exposure is performed with a 5-inch photomask. All the sectors can be written by exchanging the five photomasks and exposing the pattern while moving the Si substrate.

That is, by drawing a pattern corresponding to each on each photomask to form five sheets, it is possible to prevent the pattern seams from appearing in the middle of the sector, and to read and write data normally. become able to.

FIG. 6 shows an example of application of the present invention to a 3.5 inch storage medium. The outer diameter of a 3.5-inch storage medium is 96 m
m. The effective exposure area on the Si wafer is 15 m when the reduction exposure is 1/5 with a 3.5-inch photomask.
Since it is m square, one photomask cannot cover from the inner end (inner peripheral portion) to the outer end (outer peripheral portion) of the sector. For this reason, it is necessary to connect a plurality of photomasks. The deviation of the servo signal in the θ direction (circumferential direction) in one sector has a great influence on the reading and writing of data, but the R direction of the servo pattern ( The deviation in the radial direction does not occur as much as the degree of influence seen in the θ direction. Also, if the influence of the joint in the R direction becomes a problem, if the joint in the R direction has the same diameter over the entire circumference, it is possible to take measures if it is set so that only the boundary portion is not used. Become.

An example of applying the method of dividing the pattern in the R and θ directions to the pattern of the 3.5-inch master disk is shown in FIG. 6. From the figure, the photomask is You can see that it consists of 59 sheets. By doing so, it is possible to reduce the influence of the stepper misalignment in the photo process and create a servo pattern on the master disk.

[0040]

As described above, according to the present invention,
Since the servo pattern existing on one photomask is used as a sector unit, even if the photomask is displaced,
It can be made less susceptible to that effect.

Further, according to the present invention, when the size of the magnetic storage medium is large and one sector cannot fit in one photomask, the sector is divided into a circle and a radial direction, By dividing the photomask into a plurality of photomasks, it is possible to deal with it, and it is possible to manufacture a master disk corresponding to a high recording density at a low cost.

[Brief description of drawings]

FIG. 1 is a plan view showing a pattern configuration of sectors of a soft magnetic film of a master disk.

FIG. 2 is an enlarged view showing a pattern configuration of the sector of FIG.

FIG. 3 is an enlarged view showing a state of a signal pattern in a position / detect area of FIG.

4 is a block diagram showing a signal flow when a position control signal is detected from a signal pattern of a position detect area of the sector of FIG.

FIG. 5 is a plan view showing an arrangement configuration of a 1-inch master disk photomask according to an embodiment of the present invention.

FIG. 6 is a plan view showing an arrangement of photomasks for a 3.5-inch master disk according to another embodiment of the present invention.

FIG. 7 is a schematic perspective view showing a process of magnetic transfer in a magnetic storage medium.

FIG. 8 is a schematic cross-sectional view illustrating the principle of magnetic transfer in a magnetic storage medium.

FIG. 9 is a cross-sectional view showing a step of burying a soft magnetic layer in a master disk.

FIG. 10 is a view showing a pattern of a soft magnetic layer embedded in a 35-inch master disk, (a) is a plan view,
(B) is the elements on larger scale.

FIG. 11 is a schematic perspective view showing patterning by a direct drawing method.

FIG. 12 is a cross-sectional view showing manufacturing of a photomask by a photomask method.

FIG. 13 is a side view illustrating patterning by a reduction optical system using a photomask method.

FIG. 14 is a plan view illustrating joining of photomasks in a conventional photomask method.

[Explanation of symbols]

201 clock domain 202 Gray code area 203 Gap 204 address area 205 Position Detect Area 301 magnetic head 302 amplifier 303 Low pass filter 304 full wave rectifier 305 integrator 306 sample and hold device 307 calculator 701 Magnetic recording medium (medium) 702 Master disk 801 substrate 802 magnetic layer 803 permanent magnet 804 Silicon substrate 805 Soft magnetic layer (embedded soft magnetic Co layer) 1101 Laser oscillation tube 1102 Reflector 1103 Acoustic reflector (X direction) 1104 Acoustic reflector (Y direction) 1105 Resist surface 1106 Silicon substrate 1301 photo mask 1302 Micro optical system

Claims (3)

[Claims] 1. In manufacturing a master disk used for transferring a magnetic pattern to a magnetic storage medium, a pattern for exposing a resist on a Si substrate which is a substrate of the master disk is composed of a plurality of photomasks, A method of manufacturing a master disk for magnetic disk transfer, comprising forming a pattern of a photomask in units of sectors. 2. The pattern of each said photomask comprises:
2. The master disk for magnetic disk transfer according to claim 1, wherein, with respect to the center of the master disk, the .theta. Direction is divided in sector units and the R direction is separated by an arc having the center of the master disk as an origin. How to make. 3. A master disk for magnetic disk transfer manufactured by using the photomask according to claim 1.