JP2592311B2 - Method and apparatus for manufacturing magneto-optical recording medium - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magneto-optical recording medium, and more particularly to magneto-optical recording in which a thin film having a multilayer structure is continuously formed by a sputtering method by the orbital motion of a substrate. The present invention relates to a method and apparatus for manufacturing a medium.

[Prior Art] In recent years, magneto-optical recording media have been
It is widely used as a readable magneto-optical disk for large-capacity data files and the like.

This magneto-optical disk has a layer structure such as a dielectric layer, a recording layer, and a protective layer on a transparent substrate such as glass or plastic. In the recording layer exhibiting the magneto-optical effect, a layer composed of a rare earth metal (hereinafter, referred to as RE) and a layer composed of a transition metal (hereinafter, referred to as TM) are alternately formed in a thickness of several to several tens by at least two layers. By adopting a layer structure in which a plurality of layers are laminated, excellent characteristics such as magnetization amount, coercive force and magneto-optical effect (Kerr effect) can be obtained, and good controllability in manufacturing can be obtained.

As a manufacturing method, a method in which the RE target and the TM target are disposed in a sputtering chamber, and sputtering is performed while rotating a substrate or a substrate holder opposed to and disposed above the two targets (for example, JP-A-61-7761)
Nos. 155 and 62-71041), and by this method, a laminated film structure can be produced with a uniform distribution. In particular, since the manufacturing method is a self-revolving method, a shutter member disposed between the sputter source and the substrate to correct the film thickness distribution due to the sputter angle distribution of sputter particles can be omitted. For this reason, the adhesion efficiency of sputtered particles adhering to the substrate for forming the thin film is enhanced. Further, since there is no generation of dust due to sputter particles adhering to the shutter member, it is possible to reduce the generation of pinholes in the thin film caused by the dust adhering to the substrate, and to produce a good thin film.

[Problems to be Solved by the Invention] However, in the above-described manufacturing method, the total thickness distribution of the thin films formed by appropriately laminating on the substrate is formed uniformly. Has a problem that the film thickness distribution is not uniform as compared with the overall film thickness distribution.
For this reason, there is a problem that the C / N ratio of the manufactured magneto-optical recording medium is not sufficiently large, and that the envelope is not good.

Thus, the present inventors have conducted various experiments, and it has been confirmed that the uniformity of the film thickness distribution of each layer largely depends on the ratio of the number of revolutions of the substrate or the substrate holder.

That is, an object of the present invention is to solve the above-mentioned problems, and to make the thickness distribution of each of the RE layer and the TM layer uniform at all times, and as a result, the C / N ratio and the envelope have a good film quality. An object of the present invention is to provide a method and an apparatus for manufacturing a magneto-optical recording medium.

[Means for Solving the Problems] The object of the present invention is to provide a method for stacking at least a rare earth metal layer and a transition metal layer on a substrate. A magneto-optical recording medium that performs sputtering by the two targets while revolving the substrate so that the substrate faces the target and the revolving axis is positioned equidistant from each perpendicular passing through the geometric center of the two target surfaces. Wherein the ratio (W2 / W1) of the number of revolutions (W2) to the number of revolutions (W1) of the substrate is 4 or more, which is achieved by a method of manufacturing a magneto-optical recording medium.

Further, an object of the present invention is to stack at least a rare earth metal layer and a transition metal layer on a substrate, a rare earth metal target and a transition metal target juxtaposed in a sputtering chamber,
A rotation holder that holds the substrate so as to face the two targets, and a revolution that revolves the rotation holder such that a revolving axis is equidistant from each perpendicular passing through the geometric center of each of the target surfaces. A magneto-optical recording medium manufacturing apparatus, characterized in that sputtering is performed with the two targets so that the ratio of the number of rotations of the rotation holder to the number of rotations of the revolution holder is 4 or more. You.

Note that, in the present invention, the revolving axis is positioned equidistant from each perpendicular passing through the respective geometric centers of the surfaces of both targets, which means that the respective geometric centers of the two target surfaces (for example,
This means that each perpendicular line passing through the center of the circle in the disk target) is located on the circumference of the circle whose center is the orbital axis.

Embodiment Hereinafter, the present invention will be described in detail based on an apparatus to which the method of the present invention is applied.

FIG. 1 is a schematic view of a main part of a sputtering apparatus applied to a method of manufacturing a magneto-optical recording medium according to the present invention.

As shown in FIG. 1, in the sputtering chamber 15, targets 1a and 1b are provided on cathode electrodes 16a and 16b arranged at the bottom. Further, a magnetic field is formed on the surface of each of the targets 1a and 1b by permanent magnets 17a and 17b provided outside the sputtering chamber 15 corresponding to the back surface side.

The electrodes 16a and 16b are connected to the target power source 1 respectively.
Numerals 8 are connected so that appropriate sputtering power is applied to the targets 1a and 1b so that a desired laminated thin film can be formed.

Above the targets 1a and 1b, a plastic substrate 2 is held by a rotation holder 3 also serving as an anode electrode, and is disposed at a position where the distance between the targets 1a and 1b is substantially equal. ing. The rotation holder 3
Has a rotating shaft 7 at the center thereof, and the rotating shaft 7 extends upward through the revolution holder 4 rotated by the revolution driving motor 6. Near the upper end of the rotating shaft 7, a planetary gear 5a is fixed. The planetary gear 5a is a fixed gear fixed around the rotation shaft 8 of the revolution drive motor 6.
By meshing with the fixed gear 5b, the fixed gear 5b rotates while revolving around the fixed gear 5b.

At this time, in the present embodiment, the ratio of the rotation number of the rotation holder 3 to the rotation number of the revolution holder 4 is set to be about 4. That is, the rotation number (W2) of the rotation holder 3
The self-revolution ratio (W2 / W1), which is the ratio between the number of revolutions and the number of revolutions (W1), is also about 4.

The rotation holder 3 is configured to be mounted on the revolving holder 4 in a plural number (two in FIG. 1).

The targets 1a and 1b, for example, 1a is a transition metal, 1b
Is formed of a rare earth metal, a laminated thin film of a transition metal and a rare earth metal can be formed on the substrate 2.

Therefore, an inert gas such as an argon (Ar) gas is introduced into the sputtering chamber 15 of the sputtering apparatus configured as described above, and the sputtering power is appropriately applied to the targets 1a and 1b. The rotation holder 3
Is mounted with a plastic substrate 2 on which a dielectric layer is formed in advance.

Then, the revolving drive motor 6 is driven to rotate the revolving holder 4 and the rotation holder 3 while the substrate 2
A laminated thin film of a rare earth metal and a transition metal is formed thereon.

According to the present invention, by providing the rotation / revolution ratio of the rotation holder 3 at 4 or more, the substrate 2 rotates 2.5 times in the effective film formation region (region with high plasma density) of each of the RE and TM targets. Since the film is formed by rotating above, R
The film thickness distribution can be made uniform for each of the E layer and the TM layer.

To explain in more detail, the present inventors have performed simulation analysis and realized that the relationship between the revolution ratio and the film thickness distribution is as shown in the graph of FIG. Could clarify.

That is, as a first experiment, in order to measure the film thickness distribution of each of the RE layer and the TM layer alone, one Tb target was disposed at the center of the sputtering chamber, and the plastic substrate was opposed to these at a revolving radius of 190 mm. In addition, they were arranged so that the distance between the target and the substrate was 150 mm. Then, evacuate to a pressure of 5
After degassing to × 10 ^-7 Torr, Ar gas was introduced into the sputtering chamber to adjust the gas pressure to 1.0 × 10 ^-3 Torr. Next, while applying a discharge power of 1 kW to the Tb target to maintain sputtering and fixing the revolution speed of the substrate to 15 rpm, while changing the rotation speed of the substrate, the revolution ratio is in the range of 2 to 6. A single-layer film of Tb was formed, and the film thickness distribution was measured. The result is shown by a broken line in FIG.

As a second experiment, the distance from the center of the orbital axis to the center was 190 m in the sputtering chamber at a symmetrical position.
A Tb target and a FeCo target are arranged so as to be m, and a multilayer film is formed under the same conditions as in the first experiment.
The measurement result of the film thickness distribution of the total film thickness (45 layers) is shown by a solid line in FIG.

From FIG. 2, it can be seen that the film thickness distribution of the total film thickness (45 layers) of the multilayer film is constant over the entire region except for the vicinity of an integer value. It was confirmed that when the revolution ratio became 4 or less, it rapidly deteriorated.

When the recording layer is sputtered on the magneto-optical recording medium by the revolving method, the RE metal layer and the TM metal layer are sputtered in a laminated structure, as described above, to improve the C / N ratio, the envelope, etc. It is only necessary to make the film thickness distribution uniform,
By sputtering the self-revolving substrate holder with the self-revolving ratio of 4 or more, it is possible to obtain a film having extremely good properties such as C / N ratio and envelope.

The upper limit of the revolution ratio is not particularly limited. However, increasing the value without limit increases mechanical complexity, increases the size of the apparatus, and does not increase the effect of uniformizing the film thickness distribution. Therefore, it is preferable to keep the desired value.

[Effects of the Invention] As described above, according to the method and apparatus for manufacturing a magnetic recording medium of the present invention, since at least a rare earth metal and a transition metal are laminated on a substrate, a rare earth metal target and a transition metal are placed in a sputtering chamber. A target is arranged side by side, and the substrate is rotated and sputtered so that the substrate faces the two targets and the revolving axis is positioned equidistant from each perpendicular passing through the geometric center of each of the two target surfaces. By setting the rotation ratio of the substrate or the substrate holder at the time of rotation to 4 or more, the film thickness distribution per each layer can be made uniform, and thus the film quality with excellent characteristics such as C / N and envelope can be obtained. Is obtained.

[Examples] Hereinafter, the effects of the present invention will be further clarified by Examples.

A recording layer of a magneto-optical recording medium was formed using the apparatus of the present invention shown in FIG.

A φ8 inch Tb target 1a as a RE target and a φ8 inch FeCo target 1b as a TM target are arranged side by side at a center distance of 200 mm in the sputtering chamber 15, and two plastic substrates 2 each having a φ5.25 inch are mounted opposite to these. The rotation holder 3 was arranged so that the revolving axis was positioned equidistant from the respective center lines of the two targets, the revolving radius was 190 mm, and the distance between the target and the substrate was 150 mm. Under the above geometric conditions, the optical film Si
The plastic disc substrate 2 on which N was deposited at 800 ° was mounted on the rotation holder 3 and evacuated to a pressure of 5 × 10 ^−7.
After degassing to Torr, Ar gas was introduced into the sputtering chamber at 35 SCCM to adjust the gas pressure to 2.0 mTorr. Next, the sputtering power was applied by applying a discharge power of 900 W to the Tb target and 2100 W to the FeCo target, while the rotation holder 3 was rotated around the number of revolutions.
W1 is 30 rpm, number of revolutions W2 is 128 rpm (Rotation / revolution ratio: W2 / W1 = 4.27)
Rotate to form a film for 3 minutes and 20 seconds, and the RE layer and TM
The total film thickness of the alternately laminated recording layers was 1000 °. As a result of taking out five samples manufactured in this way and measuring the dynamic characteristics, the C / N ratio was 50 dB on average (0.9 μm bit length) and the envelope was 0.5 dB at a point of R = 30 mm from the center of the rotating substrate. The following excellent film quality was obtained.

Comparative Example Next, as a comparative example, the rotation number W2 of the substrate holder 3 was set to 68 rp.
m (revolution ratio: W2 / W1 = 2.27).
All the films were formed under the same conditions as in the above example. As a result of taking out five samples in the same manner and measuring dynamic characteristics,
At a point R = 30 mm from the center of the rotating substrate, the C / N ratio was 47 dB (0.9 μm bit length) on average, and the envelope was 1.0 dB or more.

From the above results, it was confirmed that when the RE metal and the TM metal were simultaneously formed into a layered structure in a binary structure, if the revolution ratio was 4 or less, both the C / N ratio and the envelope were reduced, and sufficient film quality was not obtained. .

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a sputtering apparatus to which the method for manufacturing a magneto-optical recording medium according to the present invention is applied, and FIG. 2 is a diagram showing a rotation / revolution ratio of a rotation / revolution substrate in a sputtering apparatus having a rotation / revolution substrate. FIG. 6 is a diagram showing a relationship with a film thickness distribution of a thin film. (Symbols in the drawing) 1a, 1b Target 2, plastic substrate 3, rotating holder 4, revolving holder 5a planetary gear, 5b fixed gear 6, revolving drive motor 7,8 … Rotating shaft 15… Sputter chamber, 16a, 16b… Electrode 17a, 17b… Permanent magnet, 18… Power supply.

Claims (2)

(57) [Claims] A rare earth metal target and a transition metal target are provided side by side in a sputtering chamber for laminating at least a rare earth metal layer and a transition metal layer on a substrate. In a method for manufacturing a magneto-optical recording medium, wherein sputtering is performed by the two targets while rotating the substrate, which is positioned at an equal distance from each perpendicular passing through each geometric center of the surface, the number of rotations of the substrate ( W2) and the number of revolutions (W1) (W2 / W
A method for manufacturing a magneto-optical recording medium, wherein 1) is 4 or more. 2. A method for laminating at least a rare earth metal layer and a transition metal layer on a substrate, wherein the rare earth metal target and the transition metal target are juxtaposed in a sputtering chamber, and the substrate is held so as to face the targets. A rotation holder, and a rotation holder for revolving the rotation holder so that a revolving axis is positioned at an equal distance from each perpendicular passing through the geometric center of each of the target surfaces; and An apparatus for manufacturing a magneto-optical recording medium, wherein sputtering is performed by using both targets so that the rotation speed ratio of the rotation holder is 4 or more.