JPH087352A - Magneto-optical recording medium and manufacture of same - Google Patents

Abstract

PURPOSE:To improve magnetic characteristic while effectively utilizing a mate rial by improving distribution of film thickness and composition. CONSTITUTION:A plurality of amorphous films 13 formed on a nonmagnetic substrate 11 in such a condition that atomic layers of rare earth RE and transistor metal TM are alternated within the same layer are working as a recording layer. The amorphous film 13 is stacked between an under layer 12 and a protection film 14 formed on the substrate and the protection film 14 is further provided with a formed reflection film 15 and moreover a protection film (UV) 16. RE and TM layers are simultaneously formed using a couple of corresponding target substances by the sputtering method while the substrate 1 1 is rotated. Therefore, two layers are formed to satisfy the relationship that a thickness ratio TM/RE of the rare earth RE and transition metal TR in one unit at the lattice surface interval L of each atomic layer stacked during rotation of the substrate 11 is larger than 1.2 but is smaller than 1.8 (1.2<(TM/RE)<1.8).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium and a method for manufacturing the same, and more particularly to a rare earth RE which is an amorphous material.
The present invention relates to a magneto-optical recording medium provided with an amorphous material composed of a periodic multilayer film in which a transition metal TM and a transition metal TM are laminated in multiple layers, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In the case of producing an optical recording medium, a magneto-optical recording medium, or other magnetic recording medium, it has recently been possible to make use of amorphous properties because of its excellent magnetic properties and the unique properties peculiar to amorphous alloys. The quality material is used relatively often. Of these, rare earth RE (Rare Earth)
h) and transition metal TM (Transition Meta)
It is known that a recording medium using an amorphous alloy film obtained by laminating a plurality of layers 1) and 1) exhibits good characteristics as a recording medium and is practically excellent even at a mass production level.

The following two methods are known for mass-producing the above-mentioned amorphous material as a magnetic material by combining a substance such as a rare earth element which is non-magnetic at room temperature with another magnetic material. . ． A method of sputtering using an alloy target composed of a rare earth RE and a transition metal TM (one-source sputtering method). ． A method using a co-sputtering method in which two targets of rare earth RE and transition metal TM are simultaneously sputtered (multi-source sputtering method).

The method using the alloy target of RE is
-TM The film composition of the amorphous film is rigorously obtained in advance, and a target (composite target or alloy target) capable of obtaining the film composition is used. It is excellent in that respect. On the other hand, the co-sputtering method using the two targets
Target power of each of the two targets during film formation,
While controlling the distribution of the film and the like, two target materials are simultaneously formed on the rotating non-magnetic substrate by sputtering. According to this method, two films are alternately formed every one rotation of the non-magnetic substrate, so that the obtained amorphous film is of course apparently and has a substantially laminated film composition. Becomes

[0005]

The method using the alloy target described above has the advantages described above, but on the other hand, the target is expensive and cannot be adjusted when the composition shifts due to the consumption of the target. However, there is a case that it is not always an appropriate method in terms of cost and mass production. In such a case, the above-mentioned co-sputtering method is adopted. In this co-sputtering method, the rare earth RE and the transition metal TM are selected depending on the rotation speed of the non-magnetic substrate on which the film is formed and the sputtering power of the two targets. Atomic layers of and are alternately laminated in a predetermined thickness.

In this co-sputtering method, when the atomic layer thickness ratio (TM / RE) of the film formed on the substrate is maintained and the thickness of each layer is increased, the magnetic characteristic is improved although the film composition remains unchanged. Occurs in which no rare earth RE is involved, or in which rare earth RE does not contribute to magnetism at all, and the magnetic properties of the amorphous material made of RE-TM thus obtained are significantly deteriorated. This phenomenon appears, for example, when the pallet supporting the substrate on which the film is formed is rotated at a low speed or the sputtering power to the target is increased to deposit an extremely thick RE layer. .

The rare earth RE itself is 300 [K].
Alternatively, it is non-magnetic at a room temperature higher than that, and exhibits characteristics as a magnetic material only when combined with a transition metal TM which is a ferromagnetic material. In combining the rare earth RE and the transition metal TM by the co-sputtering method,
When the pallet supporting the substrate is rotated at a low speed, the atomic layer thickness per layer of the transition metal TM is increased, and in particular, the atomic layer thickness per layer of the rare earth RE is rotated at a high speed or a medium speed. It is significantly thicker than when

Even if the atomic layer thickness of the rare earth RE is increased, including the thickness of the transition metal, there is no change in the composition as a result of the composition analysis by fluorescent X-ray analysis or the like. However, it does not exhibit characteristics that are originally determined by the composition, and because of the thickness of the layer thickness, the rare earth RE is necessary for obtaining a magnetic action with the transition metal TM,
Since the so-called exchange interaction cannot be exerted, a part of the rare-earth RE film formed without any relation is completely unrelated to the magnetic properties, and the film composition of RE-TM is apparently optimum from the magnetic properties. Above, an inconvenient phenomenon of transitioning to a composition rich in transition metal occurs.

The rare earth RE, which is generated when the layer thickness of the rare earth RE per layer is increased and does not participate in the magnetic characteristics, has no magnetism at room temperature and therefore does not contribute to the magnetic action and is expensive. Not only is the rare earth RE wasted, but the RE that does not contribute at all causes noise, and the amorphous magnetic film obtained is not so good in terms of magnetic characteristics. there were.
Therefore, when the amorphous material is produced by the co-sputtering method, the excellent characteristics peculiar to the co-sputtering method that the utilization efficiency and the utilization efficiency of the target material are high cannot be fully utilized. Further, the film thickness distribution and the composition distribution were also inferior to the case where the alloy target was used.

[0010]

An object of the present invention is to improve the disadvantages of the conventional example, and particularly to improve the magnetic properties while effectively utilizing the material by improving the film thickness distribution and the composition distribution. It is an object of the present invention to provide a magneto-optical recording medium having a material and a manufacturing method thereof.

[0011]

Therefore, in the present invention according to claim 1, a rare earth RE and a transition metal T are provided on a non-magnetic substrate.
The atomic layer thickness ratio is 1.2 <
(TM / RE) <1.8, and an amorphous film is provided in which the average atomic layer thickness of the rare earth RE per layer is equal to or less than the atomic radius thereof.

According to the second aspect of the present invention, Tb is used as the rare earth RE and FeCo is used as the transition metal TM.

According to the third aspect of the present invention, an amorphous film is provided on the non-magnetic substrate in which rare earth RE and transition metal TM are alternately laminated so as not to form a layer. Is adopted.

According to the fourth aspect of the present invention, the co-sputtering using two target materials of rare earth RE and transition metal TM is performed, and the atomic layer thickness ratio of rare earth RE and transition metal TM is 1.2 <(TM. /RE)<1.8, and the structure is such that the non-magnetic substrate is rotated so that the average atomic layer thickness of the rare earth RE per layer is equal to or less than the atomic radius thereof.

According to the fifth aspect of the present invention, when two kinds of target materials Tb and FeCo are arranged and the non-magnetic substrate is rotated on the opposite side of the pallet mounted in the vacuum chamber, the inside of the vacuum chamber is rotated. Ultimate vacuum of 5 × 10 ^-5 [P
a] or less and an inert gas pressure of 0.14 × 10
^In the state of ⁰ [Pa], the input power to the Tb target is 2
40 [W] and the input power to the FeCo target is 1
The recording layer is formed on the non-magnetic substrate by sputtering at 280 [W].

The present invention is intended to achieve the above-mentioned object by these means.

[0017]

When the amorphous material film is formed according to the above-mentioned relationship, the non-magnetic material itself at room temperature is magnetically coupled with other magnetic material, and the function as a magnetic material is exhibited. For example, when the amorphous material is composed of rare earth RE and transition metal TM,
A distribution in which the rare-earth RE itself, which is non-magnetic at room temperature, is magnetically coupled to the transition metal TM, which is a magnetic substance, and sufficiently exhibits its action as a magnetic substance by so-called exchange interaction, which does not contribute to the magnetic characteristics. Is less. Therefore,
The magnetic properties of the amorphous material as the magnetic film are improved and maintained at a high level. Particularly, when the average atomic layer thickness per one layer of the rare earth RE is equal to or less than the atomic radius thereof and the film composition is thin, sufficiently good characteristics can be obtained.

When the amorphous material is produced by laminating the rare earth RE layer and the transition metal TM layer in multiple layers, the layer thickness ratio is selected to be 1.2 <(TM / RE) <1.8. The amorphous material is a thin film and has sufficiently good magnetic properties.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an amorphous material (film) of this embodiment and is a partial cross-sectional view of a magneto-optical disk medium. Here, the amorphous film 13 composed of a plurality of atomic layers of the rare earth RE and the transition metal TM alternately intermingled in the same layer on the non-magnetic substrate 11 acts as a recording layer. There is. The amorphous film 13 is laminated between the base film 12 and the protective film 14 formed on the substrate, the reflective film 15 is formed on the protective film 14, and the protective film (UV) 16 is further formed. Has been done.

The RE and TM layers are simultaneously formed by the co-sputtering method using two corresponding target materials while rotating the substrate 11. When forming the layer,
As shown in FIG. 2 (A), a case where two atomic layers RE and TM have a layered structure, and as shown in FIG. 2 (B), 2
In some cases, the two atomic layers RE and TM do not have a layered structure and are alternately stacked while intermingling with each other. In this embodiment, two atomic layers RE and TM are alternately laminated in a single layer while intermingling with each other (see FIG. 2).
The amorphous film 13 of (B)) is used as the recording layer. Therefore, the layer thickness ratio between the rare earth RE and the transition metal TM in one unit at the lattice spacing L of each atomic layer laminated by one rotation of the substrate 11 is 1.2 <(TM / RE) <.
Two layers are formed so as to satisfy the relational expression of 1.8.

This will be described in detail. Here, Tb is used as the rare earth and FeCo is used as the transition metal TM. Tb and FeCo are simultaneously laminated on the substrate 11 by the above-described co-sputtering method using two target materials under the film formation conditions illustrated below.

FIG. 3 is a partial front sectional view showing a co-sputtering apparatus used for film formation, and FIG. 4 is a bottom view of the co-sputtering apparatus shown in FIG. Two target materials 3 of Tb and FeCo are placed in the vacuum chamber 31.
While placing 2 and 33, the plurality of substrates 11 are rotated on the surfaces of the pallets 34 facing the targets 32 and 33, and after introducing the inert gas into the vacuum chamber 31, the pallets 34 are rotated. When an electric field is applied at the same time, plasma discharge occurs,
Each time the pallet 34 is sputtered, T is placed on the substrate 11.
b and FeCoTi are alternately laminated.

Actually, the ultimate vacuum in the vacuum chamber 31 is 5 ×
10 ^-5 [Pa] or less, argon gas pressure during sputtering of 0.
In the state of 14 × 10 ⁰ [Pa], the input power to the Tb target was set to 240 [W] and the input power to the FeCo target was set to 1280 [W], and co-sputtering was performed for 108 seconds.

When the atomic diameter of Tb is 3.56 angstroms, the atomic diameter of Fe is 2.48 angstroms, and the atomic diameter of Co is 2.50 angstroms, it is 1
At the lattice spacing L of the unit, the average total number of atoms is Tb.
It was found that the film thickness distribution and the composition distribution were improved in a state smaller than one atomic layer, and the magnetic characteristics were optimal. FIG. 5 shows the result of examining the amorphous film 13 actually formed. The horizontal axis represents the radial direction of the disk, and the vertical axis represents the standard values of film thickness and composition at the innermost diameter. In FIG. 5, the solid line represents the case where the Tb atomic layer is smaller than the Tb atomic radius, that is, the case where the Tb atomic layer has a film structure in which the layers are alternately laminated while intermingling with each other as shown in FIG. 2B. Shows. On the other hand, the dotted line shows the case of the stacked film structure shown in FIG. 2A, in which the Tb atomic layer is larger than the Tb atomic radius. As is clear from this evaluation,
In this embodiment, both the film thickness and the composition are stable.

When an amorphous film is produced with a film composition such that the average atomic layer thickness of Tb is not more than the Tb atomic diameter, the atomic layer of Tb at the nuclear lattice spacing L is a thin film having an average layer thickness of 3.56 angstroms or less. Therefore, it is magnetically coupled to the transition metal FeCo, and due to the exchange interaction, Tb which is originally non-magnetic at room temperature.
Shows the characteristics as a magnetic material. Therefore, Tb that does not contribute to magnetism is eliminated in each atomic layer of the amorphous film, and thus expensive Tb can be effectively used. Also,
The magnetic characteristics are stable, and a good magnetic film that is magnetically stable can be obtained. Further, by satisfying the conditions in the above-mentioned manufacturing method, it is possible to efficiently manufacture a good amorphous material that is magnetically stable, that is, a magnetic film.

[0026]

Since the present invention is constructed and functions as described above, according to this, an amorphous material (film) having a wide and uniform film thickness and composition can be stably obtained. In addition, non-metals or rare earths which are originally non-magnetic at room temperature become fully magnetized by bonding with a transition metal, which is a magnetic material, at the atomic level, and non-magnetic materials that do not contribute or do not contribute to magnetism. Rare earths are lost. Since there is no rare earth element or the like that does not contribute to or contribute to magnetism, it is possible to reduce noise, and to effectively use expensive materials and save materials. As described above, a magneto-optical recording medium having a non-conventional amorphous material capable of improving magnetic characteristics while effectively utilizing the material by improving the film thickness distribution and the composition distribution, and a manufacturing method thereof are provided. be able to.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a film structure of a magneto-optical disk medium showing an embodiment of the present invention.

2A and 2B are cross-sectional views of an amorphous film according to the related art and the present embodiment, FIG. 2A is a cross-sectional view illustrating a conventional example, and FIG. 2B is a cross-section of the amorphous film according to the present embodiment. It is a figure.

FIG. 3 is a partial front cross-sectional view of a co-sputtering device used for carrying out the method of manufacturing a magneto-optical disk medium of the present invention.

FIG. 4 is a bottom view of the co-sputtering device shown in FIG.

5 shows evaluation of the amorphous film 13 according to this example, FIG. 5 (A) is a graph of film thickness, and FIG. 5 (B).
[Fig. 3] is a graph of composition.

[Explanation of symbols]

 L Lattice spacing 11 Non-magnetic substrate 12 Underlayer film 13 Amorphous film 14 Protective film 15 Reflective film 16 Protective film (UV) 21 RE 22 TM 23 Amorphous film 31 Vacuum chamber 32 RE target 33 TM target 34 Palette 35 Rotation Axis 36 substrate holder

Claims (5)

[Claims] 1. A non-magnetic substrate is composed of a periodic multilayer film of rare earth RE and transition metal TM, and the atomic layer thickness ratio is 1.2.
<(TM / RE) <1.8, and a magneto-optical recording medium provided with an amorphous film laminated such that the average atomic layer thickness of rare earth RE per layer is equal to or less than the atomic radius thereof. 2. The magneto-optical recording medium according to claim 1, wherein Tb is used as the rare earth RE and FeCo is used as the transition metal TM. 3. A magneto-optical recording medium comprising an amorphous film in which the rare earth RE and the transition metal TM are alternately laminated so as not to form a layer on a non-magnetic substrate. 4. A co-sputtering using two target materials of rare earth RE and transition metal TM, wherein the atomic layer thickness ratio of rare earth RE and transition metal TM is 1.2 <(TM / RE) <.
A method for manufacturing a magneto-optical recording medium, characterized in that the non-magnetic substrate is rotated such that the average atomic layer thickness of the rare earth RE per layer is 1.8 or less in the relationship of 1.8. 5. Two kinds of target materials Tb and FeCo
When the non-magnetic substrate is rotated on the opposite side of the pallet mounted in the vacuum tank, the ultimate vacuum in the vacuum tank is 5 × 10 ⁻⁵ [Pa] or less and the pressure of the inert gas is A recording layer is formed on the non-magnetic substrate by sputtering with a power of 240 [W] applied to the Tb target and a power of 1280 [W] applied to the FeCo target under the condition of 0.14 × 10 ⁰ [Pa]. A method for manufacturing a magneto-optical recording medium, characterized by: