JPH05242469A - Magnetic disk and its production - Google Patents

Abstract

PURPOSE:To produce a magnetic disk which can undergo reduction in size and increase in capacity without reducing the recording density by forming an information pattern on an information layer under a magnetic recording layer. CONSTITUTION:A tracking servo pattern 3 is formed on the surface of a discoid transparent glass substrate 1 with a central hole, a silicon dioxide film 4 and a transparent glass film 5 are successively formed on the surface of the substrate 1 with the formed pattern 3 and a transparent magnetic recording layer 6 for recording and reproducing data is formed on the glass film 5. A transparent magnetic recording layer is further formed on the underside of the substrate 1 to obtain the objective magnetic disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk used for a fixed magnetic disk device used as an external storage device for computers, workstations, desktop personal computers, laptop personal computers, notebook personal computers and the like. In particular, the present invention relates to a high density magnetic disk adopting an optical tracking servo technology capable of greatly improving the track density and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, a fixed magnetic disk and a flexible magnetic disk are required to have a higher density as the information capacity increases. Higher densities of these are due to higher Bs, higher Hc, thinner film, adoption of perpendicular magnetization film of magnetic recording medium, higher performance of magnetic head, and reduction of flying height of fixed magnetic disk head. It is being advanced. Further, as the track density of the magnetic recording medium is improved, it is necessary to track the magnetic head with high accuracy.

Conventionally, as a method of tracking servo,
The fixed magnetic disk has a servo surface servo and the flexible magnetic disk has a sector servo. However, as the track width becomes narrower, the accuracy required for tracking cannot be obtained by such a method. Therefore, attempts to use the recording surface of the disc effectively and use the recording capacity per disc as large as possible have started to be provided. For example, in a fixed magnetic disk, for detecting the position of a track, holes (pits) are formed at regular intervals along the track, and the position is detected by laser light (Nikkei Electronics. 1991.4.1.
NO. 524), since the servo is performed by light in the flexible magnetic disk, a method for physically providing a pit for the servo on the surface of the magnetic disk to guide the magnetic head along the track almost continuously (Nikkei) Mechanical 1
991.8.5) is beginning to be adopted.

[0004]

Optically performing the tracking servo as described above has a much higher control accuracy than the conventional method using magnetic signals, which means that in the magneto-optical recording. Proven in the case of tracking. Using this for a magnetic disk is very effective.

However, in the above-described method of optically performing the tracking servo of the magnetic disk, since the pits for the servo signal are provided by utilizing a part which should originally be the magnetic recording surface, the magnetic disk There is a problem that the recording density is reduced by the amount of using the pits for the servo signal.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a magnetic disk in which the recording density of the magnetic disk does not decrease and a method for manufacturing the same.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a substrate having a predetermined property with respect to light, and information for detecting a data recording / reproducing position having a property different from the property of the substrate for light. A magnetic disk having a pattern, an information layer formed on a substrate, and a magnetic recording layer formed on the information layer for recording / reproducing data.

[0008]

According to the present invention, since the information layer below the magnetic recording layer for recording / reproducing data has the information pattern for detecting the recording / reproducing position of the data, the magnetic recording layer It is not necessary to have the information pattern, and data recording / reproduction can be efficiently performed on the magnetic recording layer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 6 is a side view showing the structure of a magnetic disk of an embodiment according to the present invention. That is, the magnetic disk is provided with a disc-shaped light-transmissive glass substrate 1 having a hole in the center (see FIG. 1), and a light-reflecting film 2 of metal or the like is formed on the surface thereof in a pattern required for tracking servo. An etched tracking servo pattern 3 is formed (see FIGS. 2 and 3). A silicon dioxide film 4 and a light-transmitting glass film 5 are formed on the surface of the light-transmitting glass substrate 1 on which the tracking servo pattern 3 is formed, and data is recorded on the surface of the light-transmitting glass film 5. A light transmissive magnetic recording magnetic film 6 for reproduction is formed. A light-transmitting magnetic recording magnetic film 6 is formed on the other surface of the light-transmitting glass substrate 1 (not shown).

Next, an embodiment of the method of manufacturing the magnetic disk of the above embodiment will be described.

First, as shown in FIG. 1, a light-reflecting film 2 is formed on one surface of a doughnut-shaped light-transmissive glass substrate 1 having a hole in the center by sputtering, vapor deposition technique or the like. The light reflection film 2 is preferably a metal film having excellent heat resistance and oxidation resistance. The light reflection film 2 is etched by photolithography into a pattern shape required for a tracking servo as shown in FIG. 2 to form a tracking servo pattern 3 (tracking servo pattern 3 Details are shown in Fig. 3. The dotted line in the drawing indicates the track center line 9.).

Next, as shown in FIG. 4, on the transparent glass substrate 1 on which the tracking servo pattern 3 is formed,
A method of forming a silicon dioxide film 4 by a sputtering method or the like, and further forming a light-transmissive glass film 5 on the silicon dioxide film 4 by a sputtering method, an EB vapor deposition method, or coating glass particles and melting them by heating to form a film, etc. Formed by. At this time, the surface of the light transmissive glass film 5 has the tracking servo pattern 3
Due to the unevenness due to, the unevenness is formed at least about the thickness of the light reflection film 2.

If the light-transmitting magnetic recording magnetic film 6 is formed on the surface of the light-transmitting glass film 5 in this state, the surface is also formed with the same degree of unevenness, and data is recorded using the magnetic head. When reproduction is performed, modulation noise may occur due to the degree of unevenness, and in some cases, the running property of the head may be impaired.

Therefore, after forming the light-transmitting glass film 5 on the surface as described above, as shown in FIG. 5, two presses having a smooth surface while the light-transmitting glass substrate 1 is heated. It is sandwiched between the molds 7 and pressed to eliminate the surface irregularities and form a smooth surface. The arrow 8 in the figure indicates the pressing direction. The light transmissive magnetic recording magnetic film 6 is formed on the surface of the light transmissive glass film 5 formed on the smooth surface. The light transmissive magnetic recording magnetic film 6 is made of, for example, a cobalt-ferrite perpendicular magnetic anisotropy film and is formed by plasma excitation / MO-CVD method. Further, on the other surface of the light transmissive glass substrate 1, the same light transmission as the above is applied to the surface of the light transmissive glass substrate 1 which is formed smoothly without providing the tracking servo pattern 3 as described above. Of the cobalt-ferrite perpendicular magnetic anisotropy film, which is the magnetic recording magnetic film 6, by plasma excitation / MO
-The tracking servo on this surface is formed by the CVD method.
The tracking servo pattern 3 formed on the other surface is used. In this way, the magnetic disk as shown in FIG. 6 is completed (the light transmissive magnetic recording magnetic film on the other surface is not shown).

Next, a specific manufacturing method of the above embodiment will be described.

First, the thickness is 0.8 mm and the inner shape is 2.
An Au film having a thickness of 0.4 μm was formed on the surface of a soda lime glass disk substrate 1 having an outer diameter of 0 mm and an outer diameter of 65 mm by a sputtering method. By using a photolithography technique for the Au film, as shown in FIG. 7, the track width direction length is 3 μm and the track direction length is 20 μm.
Tracking servo patterns 3 each having a micron elliptical light-reflecting film were formed along the track center line 9 at a pitch of 100 microns. Such tracking servo patterns 3 were provided on both sides of the track center line 9 so that the distance between the track center line 9 and the center of the tracking servo pattern 3 was 1.5 μm. Further, the tracking servo patterns 3 on both sides of the track center line 9 are formed such that the positional relationship between them is displaced from each other by 30 microns in the track direction.

Next, a silicon dioxide film 4 having a thickness of about 0.1 micron is formed on the silicon dioxide film 4 by the sputtering method, and the silicon dioxide film 4 and the soda lime glass disk substrate 1 have thermal characteristics. Almost the same light transmissive glass film 5 was formed to a thickness of about 1 micron by the sputtering method. The surface of the soda lime glass disk substrate 1 thus formed is uneven due to the thickness of the tracking servo pattern 3. In order to eliminate the unevenness and smooth the surface, the soda-lime glass disk substrate 1 was heated to 670 ° C. and pressed by a pressing die 7 having a smooth surface. The soda-lime glass disk substrate 1 thus obtained had an average roughness of 50 angstroms on the surface and a waviness of about 1 micron on the entire surface.

In the above description, the silicon dioxide film 4 is provided because when the soda lime glass disk substrate 1 is heated and pressed, the light transmissive glass film 5 on the upper surface of the tracking servo pattern 3 of Au film is formed. The purpose is to prevent the gold from being repelled and removed from the surface of gold by heating, and it is not necessary to provide the silicon dioxide film 4 if a glass film that is well compatible with the metal film of the tracking servo pattern 3 is used.

Next, the tracking operation using the magnetic disk of the above embodiment will be described.

First, as shown in FIG. 7, the size of the servo light spot 10 which is transmitted through the light transmissive magnetic recording magnetic film 6 and applied to the tracking servo pattern 3 is set to 4 μm. As the light source of the servo light spot 10,
A semiconductor laser light source (not shown) provided on the magnetic recording / reproducing head slider is used to irradiate a servo light spot 10 to reflect light from the tracking servo patterns 3 on both sides of the track center line 9. (Amount of light from the shaded area in FIG. 7) is detected by a light receiving element (not shown) and converted into an electric signal. Next, the position of the servo light spot 10 was corrected so that the detected difference between the electric signal intensities on both sides was eliminated, thereby controlling the tracking of the magnetic recording / reproducing head.

According to the above method using the magnetic disk, the tracking accuracy is 0.1 to 0.2 μm, which is much higher than the case of using the magnetic head of several μm. Further, since the tracking servo pattern 3 is provided very close to the surface of the magnetic recording film 1 of the magnetic disk (up to 1 μm), the servo light of the light source for irradiating the tracking servo pattern 3 is used. In order to reduce the size of the spot 10, it is not necessary to narrow down the spread of the light, or even if it is necessary to narrow down the spot, a minute lens is sufficient, and it is very easy to mount it on a small slider such as a magnetic recording / reproducing head. Easy to do.

In the above embodiment, a light-transmissive glass substrate is used as the substrate, and a metal film that reflects light is used as the tracking servo pattern 3 which is an information pattern. It is only necessary to be able to detect the distinction from the information pattern, for example, using a metallic plate member for the substrate,
The information pattern may be composed of a light absorbing film, and in short, it suffices that the substrate and the information pattern have different properties with respect to light.

Further, in the above-mentioned embodiment, the light transmissive magnetic recording magnetic film is used for the magnetic recording layer, but instead of this, the detection of the tracking servo pattern 3 by light is performed from the glass substrate side, You may use the magnetic recording magnetic film of.

Further, in the above embodiment, the light-transmissive glass film 5 is provided between the substrate and the magnetic recording layer, but the present invention is not limited to this, and when the information layer having the information pattern has no unevenness,
The transparent glass film 5 may be omitted.

Further, in the above embodiment, the information layer having the information pattern is provided separately from the substrate, but instead of this, the information layer may be formed by embedding the information pattern on the surface of the substrate.

Further, in the above embodiment, the Au film is used as the light reflecting film, but the light reflecting film is not limited to this, and other noble metal film may be used.

Further, in the above embodiment, the light-transmissive glass film 5 is formed by the sputtering method, but the invention is not limited to this, and it may be formed by, for example, the EB vapor deposition method. Alternatively, the substrate is placed on the bottom of a container in which glass particles are dispersed in a solvent, the container is rotated at high speed, the glass particles are deposited on the substrate surface by the centrifugal force, and then the surface is heated to form a glass film. It may be allowed to.

Further, a glass paste may be printed by a printing method and heat-treated to form a glass layer.

[0030]

As is clear from the above description, the present invention has an advantage that the recording density of the magnetic disk does not decrease.

Further, since the recording density does not decrease, there is an advantage that the magnetic disk can be made small and have a large capacity.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which a light reflection film is formed on a substrate in a manufacturing process of a magnetic disk according to an embodiment of the present invention.

FIG. 2 shows a tracking servo pattern on the substrate of the embodiment.
FIG. 3 is a perspective view showing a state in which a connector is formed.

FIG. 3 is a partially enlarged view of the tracking servo pattern of the same embodiment.

FIG. 4 is a perspective view showing a state in which a glass film or the like is formed on the substrate of the example.

FIG. 5 is a side view showing a method of pressing the substrate for smoothing the surface of the glass film in the example.

FIG. 6 is a side view of the magnetic disk of the embodiment.

FIG. 7 is a diagram showing a method of tracking servo by irradiating a light spot using the magnetic disk of one embodiment according to the present invention.

[Explanation of symbols]

 1 Light-transmissive glass substrate 2 Light-reflective film 3 Tracking pattern 4 Silicon dioxide film 5 Light-transmissive glass film 6 Light-transmissive magnetic recording magnetic film 7 Press die 9 Track center line 10 Servo light spot

Claims (11)

[Claims] 1. A substrate having a predetermined property for light,
Having a property different from the property of the substrate for light, having an information pattern for detecting a recording / reproducing position of data, an information layer formed on the substrate, and formed on the information layer, A magnetic disk comprising a magnetic recording layer for recording / reproducing the data. 2. The substrate is a substrate having optical transparency,
2. The magnetic disk according to claim 1, wherein the pattern of the information layer is formed of a light reflecting film that reflects light. 3. The magnetic disk according to claim 2, wherein the light reflection film is a noble metal film. 4. The magnetic disk according to claim 1, wherein the information pattern is formed in the vicinity of the surface of the substrate having a predetermined property with respect to the preceding light in a plane parallel to the surface. 5. A film having an information pattern for detecting a data recording / reproducing position on an inner surface of a substrate having a predetermined property with respect to light, the property being different from the property of the substrate with respect to light. And a magnetic recording layer formed on the magnetic recording layer. 6. The substrate is a light-transmitting substrate, and the information pattern is formed of a light-reflecting film that reflects light, and a light-transmitting film is further formed thereon, or a silicon oxide film is formed thereon. After being formed, the substrate is heated and pressed to smooth the surface of the light-transmissive film, and the smoothed surface of the light-transmissive film has a light-transmitting property. The method of manufacturing a magnetic disk according to claim 5, wherein a magnetic recording layer is formed. 7. The method of manufacturing a magnetic disk according to claim 6, wherein the light-transmissive film is made of glass. 8. The method of manufacturing a magnetic disk according to claim 6, wherein the pressing is performed by sandwiching the pressing mold made of a heat resistant and oxidation resistant material between two press dies having a smooth surface. 9. The method of manufacturing a magnetic disk according to claim 8, wherein the optically transparent film is formed by sputtering. 10. The light-transmissive film comprises: placing a light-transmissive substrate on the bottom of a container in which glass particles are dispersed in a solvent, rotating the container at a high speed, and utilizing centrifugal force to deposit the glass particles on the surface of the substrate. 9. The method of manufacturing a magnetic disk according to claim 8, wherein the magnetic disk is formed by depositing and then heating to form a glass film. 11. The method of manufacturing a magnetic disk according to claim 8, wherein the light-transmissive film is formed by printing glass paste and heat-treating it to form a glass film.