JPH06309714A - Method for manufacturing magneto-optical recording medium - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] The present invention provides a method for manufacturing a magneto-optical recording medium, which can manufacture with high productivity a magneto-optical recording medium in which the adhesion strength between a plastic substrate and a recording layer is increased. The purpose is. A method for manufacturing a magneto-optical recording medium according to the present invention is a method for manufacturing a magneto-optical recording medium in which a first dielectric layer, a recording layer, a second dielectric layer and a reflective layer are sequentially formed on a plastic substrate. In the method, at least the dielectric layer on the side in contact with the substrate is formed by a sputtering method in pure Ar gas, using a Si ₃ N ₄ sintered body containing 5 wt% to 30 wt% of oxide as a target. It is characterized by doing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magneto-optical recording medium, and more particularly to a method of manufacturing a magneto-optical recording medium in which the adhesion strength between a plastic substrate and a recording layer is increased.

[0002]

2. Description of the Related Art Generally, a magneto-optical recording medium uses a plastic plate such as polycarbonate as a substrate on which a first dielectric layer, a recording layer, a second dielectric layer and a reflective layer are sequentially formed. It is said that. Each of these layers is formed by a DC or RF sputtering method, and this dielectric layer is usually formed by using a Si target and
Although it is formed by reactive sputtering in an r, N ₂ mixed gas atmosphere, the film thus formed has a drawback that it does not have sufficient adhesive strength with a plastic substrate and is easily peeled off.

Therefore, in order to increase the adhesion strength, there have been proposed methods such as treating the surface of the plastic substrate with oxygen plasma, and sputter etching the plastic substrate in advance before film formation.
All of these have a problem that the number of processes is increased and thus the productivity is lowered and the apparatus is complicated.

[0004]

The first dielectric layer formed directly on the plastic substrate has a role of blocking moisture released from the substrate from the recording layer. Besides, it also serves to improve the Kerr rotation angle of this magneto-optical recording medium and also to obtain the Kerr enhancement effect. However, when there is floating oxygen in this dielectric layer, it causes refraction of the dielectric by this. Since it is necessary to increase the film thickness in order to obtain the same enhancement effect due to the decrease in the rate, there is a problem that if the film thickness is increased, the film formation time becomes long and productivity deteriorates. .

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a magneto-optical recording medium which solves the above disadvantages and problems, and it relates to a first dielectric layer, a recording layer, and a recording layer on a plastic substrate. In a method for manufacturing a magneto-optical recording medium in which a layer, a second dielectric layer and a reflective layer are sequentially formed, at least the dielectric layer on the side in contact with the substrate contains Si in an amount of 5% by weight or more and 30% by weight or less. It is characterized in that a film is formed by a sputtering method in a pure Ar gas targeting a ₃ N ₄ sintered body.

That is, as a result of various studies on the manufacturing method of the magneto-optical recording medium in which the adhesion strength between the plastic substrate and the recording layer was increased, the present inventors found that the first dielectric layer, the recording layer and the second layer were formed on the plastic substrate. In a method of manufacturing a magneto-optical recording medium in which a dielectric layer and a reflective layer are sequentially formed, this first dielectric layer is targeted at a Si ₃ N ₄ sintered body containing an oxide, and this is placed in a pure Ar gas atmosphere. When sputtering to form a film, SiN as a dielectric layer is obtained here.
It has been found that the layer has a high adhesion strength, and this also has a high refractive index, and according to this, it is advantageous to manufacture a magneto-optical recording medium having a high adhesion strength between the plastic substrate and the recording layer. The present invention has been completed after confirming that the above can be achieved. This will be described in more detail below.

[0007]

The present invention relates to a method of manufacturing a magneto-optical recording medium, which has a first dielectric layer, a recording layer, a second dielectric layer and a reflective layer formed in sequence on a plastic substrate as described above. In the method of manufacturing a magneto-optical recording medium, at least the dielectric layer on the side in contact with the substrate contains 5% by weight of oxide.
As described above, the feature is that the film is formed by the sputtering method in the pure Ar gas, which targets Si ₃ N ₄ containing 30% by weight or less. According to this, the SiN produced by this method is used. Since the dielectric layer made of has a high adhesive strength, the substrate and the recording layer also have a high adhesive strength, and since this dielectric layer has a high refractive index, it can be made thin and therefore This gives the advantage that it can be deposited in a short time.

The magneto-optical recording medium according to the present invention is manufactured by a known method in which a first dielectric layer, a recording layer, a second dielectric layer and a reflective layer are sequentially formed on a plastic substrate such as a polycarbonate resin. The magneto-optical recording medium itself is a known one and is not new. In this manufacturing method, a plastic substrate is attached to a disk carrier after a degassing process for 1 hour or more in an oven set at 90 ° C., and then placed in a vacuum exhaust chamber (loading chamber). The disk carrier is evacuated to a vacuum in the loading chamber and sent to the film forming chamber.

In this film forming chamber, S as a first dielectric layer is formed on the plastic substrate according to a known film forming process.
A layer made of a rare earth metal and an iron-based amorphous alloy as an iN layer and a recording layer, for example, TbFeCo, GdDyFeCo, etc. is formed, and a SiN layer as a second dielectric layer and a reflective layer are further formed thereon. Al alloy layers are formed by DC or RF sputtering, respectively.

However, in the present invention, the film formation of the first dielectric layer is carried out under normal pressure, hot press or HIP (Hot Isosta).
The target is a Si ₃ N ₄ sintered body created by a method such as tic press), and this Si ₃ N ₄ sintered body target is one in which a metal or semimetal oxide is used as a binder. To be done. This metal or metalloid oxide is represented by MxOy, and M is at least one metal element selected from rare earth elements including Al, Zr, Si and Y, Sc, where x and y are Mol%, which is preferably 30 ≦ x ≦ 70 and 30 ≦ y ≦ 70.

The first dielectric layer is formed by using this Si ₃ N ₄ sintered body target at a pressure of 5.0 × 10 ⁻⁴ to 1.0 × 10 5.
^It may be carried out by sputtering using an RF voltage in a pure Ar atmosphere of ^-2 Torr. The amount of oxide contained in the Si ₃ N ₄ sintered body target is 5% by weight or more and 30% by weight or more. The adhesive strength of the dielectric layer obtained by this is preferably increased, so that the adhesive strength between the substrate and the recording layer can also be increased, and this film also has a high refractive index. Therefore, it is possible to reduce this film thickness, and therefore the film formation time can be shortened,
The advantage that a magneto-optical recording medium can be obtained with high productivity is given.

The formation of the recording layer, the second dielectric layer, and the reflective layer after the formation of the first dielectric layer may be performed by a known method, and thus the formation of this recording layer is usually used. It may be performed by DC sputtering in an Ar gas atmosphere using an alloy target having a composition such as TbFeCo or GdDyFeCo, and the second dielectric layer is formed by the same method as the above-mentioned first dielectric. However, this may be performed by RF reactive sputtering in a mixed gas atmosphere of Ar and N ₂ using a known Si or Si ₃ N ₄ target, and the reflective layer is formed of Al and other additives. DC sputtering may be performed in an Ar gas atmosphere using a target made of

[0013]

EXAMPLES Next, examples and comparative examples of the present invention will be described. Examples 1 to 3, Comparative Examples 1 to 4 A polycarbonate substrate with a diameter of 86 mm and a thickness of 1.2 mm and having a tracking groove is left in an oven heated to 90 ° C. for 2 hours to dry and then mounted on a disk carrier. Then, it was placed in the loading chamber and evacuated.

Then, in order to form a first dielectric layer on this substrate, Si ₃ N ₄ containing Al ₂ O ₃ and Y ₂ O ₃ is sintered by hot pressing in an N ₂ gas atmosphere. Obtained with Al ₂ O ₃
The content of Y ₂ O _{3 is} the amount shown in Table 1 below, and three types of Si ₃
Targeting N ₄ sintered body, 1.0 × in pure Ar gas atmosphere
After RF sputtering under a pressure of 10 ^-3 Torr to form a first dielectric layer with a thickness of 30 nm on this substrate, a recording layer is formed with a thickness of 13 nm from TbFeCo by a known method, Furthermore, as a second dielectric layer, a SiN layer with a thickness of 25 nm,
Magneto-optical recording media (Examples 1 to 3) were manufactured by sequentially forming a reflective layer with a film thickness of 60 nm.

For comparison of this magneto-optical recording medium, the first and second dielectric layers were formed by using a known Si target, and the flow ratio of Ar: N ₂ was 10: 3.
A recording layer, a second dielectric layer, and a reflective layer were formed in the same manner as in Example 1 except that RF reactive sputtering was performed at 1.0 × 10 ⁻³ Torr in an atmosphere set to 3. Magnetic recording media (Comparative Examples 1 to 3) were produced.

Next, an adhesive tape having a width of 18 mm was attached to the film surfaces of the 6 types of magneto-optical recording media obtained in this way, cuts were made on the films on both sides of this adhesive tape, and this was attached to a tensile tester. When the adhesion strength of the film was examined, the results shown in Table 1 were obtained, and the adhesive strength of the example was higher than that of the comparative example.

In this magneto-optical recording medium, the content of Al ₂ O ₃ and Y ₂ O ₃ which are different from each other is 12% by weight of Al ₂ O _{3 and} 24% by weight of Y ₂ O ₃ Si ₃ The first dielectric layer is formed by the same method as above using the N ₄ sintered body as a target, and the recording layer,
The second dielectric layer and the reflective layer were also formed in the same manner as above to produce the magneto-optical recording medium of Comparative Example 4, and
3. When the refractive index of the magneto-optical recording medium of Comparative Example 4 was measured, the results as shown in the following Table 2 were obtained, and since the example has a larger refractive index than the comparative example,
This is because the film surface can be thinned in order to obtain the car enhancement effect, and thus the productivity can be improved.

[0018]

[Table 1]

[Table 2]

[0019]

As described above, the present invention relates to a method of manufacturing a magneto-optical recording medium, which comprises a plastic substrate, a first dielectric layer, a recording layer, a second dielectric layer and a reflective layer. In a method of manufacturing a magneto-optical recording medium in which layers are sequentially formed, at least the dielectric on the side in contact with the substrate is a Si ₃ N ₄ sintered body containing 5 wt% or more and 30 wt% or less of an oxide as a target. The present invention is characterized in that the film is formed by a sputtering method in Ar gas. According to this method, the SiN layer as the dielectric layer obtained here can be made to have a high adhesive strength, so that the plastic It is possible to obtain a magneto-optical recording medium in which the adhesion strength between the substrate and the recording layer is large, and it is possible to make the dielectric material thin because the refractive index of the medium can be large. Advantage is provided that can be produced with good productivity body.

Claims (2)

[Claims] 1. In a method of manufacturing a magneto-optical recording medium, wherein a first dielectric layer, a recording layer, a second dielectric layer and a reflective layer are sequentially formed on a plastic substrate, at least the dielectric on the side in contact with the substrate. Body layer, oxide 5% or more, 30% by weight
Pure Ar targeting the Si ₃ N ₄ sintered body containing
A method of manufacturing a magneto-optical recording medium, which comprises forming a film by a sputtering method in a gas. 2. The oxide contained in the Si ₃ N ₄ target is M _x.
O _y (where M is Al, Zr, Si or one or more metals selected from rare earth elements including Y and Sc, x and y are mol% 30 ≦ x ≦ 70, 30 ≦ y ≦ 70) The method of manufacturing a magneto-optical recording medium according to claim 1, wherein