JP3344449B2 - Magnetic recording medium and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium suitable for high-density magnetic recording, which is excellent in oxidation resistance and corrosion resistance and has a suitable coercive force capable of avoiding magnetic saturation of a magnetic head which is currently widely used. More particularly, the present invention relates to a magnetic recording medium comprising a perpendicular magnetization film having a coercive force smaller than 3000 Oe and a large squareness ratio (value corrected for demagnetizing field).

[0002]

2. Description of the Related Art In recent years, the trend of downsizing and high reliability of information devices and systems has been remarkable, and the demand for high-density recording of magnetic recording media has been increasing more and more. As a magnetic recording medium that satisfies such characteristics, the development of a perpendicular magnetization film has been active and has been put to practical use. That is, since the perpendicular magnetization film is magnetized in a direction perpendicular to the film surface, there is no demagnetization effect, and high-density recording is possible.

[0003] As a perpendicular magnetization film, an alloy film such as a CoCr alloy has been conventionally proposed, but the alloy film is coated with a carbon film having a thickness of about 100 to 200 mm on the surface in order to prevent deterioration of magnetic characteristics due to oxidation. Need to
As a result, the loss of spacing (the distance between the magnetic head and the medium) is increased by the thickness of the carbon film, and it is not suitable for high-density recording. Therefore, it is strongly required that the perpendicular magnetization film be an oxide that is stable against oxidation.

With respect to the coercive force of the perpendicular magnetization film, it is required that the coercive force be suitable for avoiding magnetic saturation of the head which is widely used at present, especially, a coercive force lower than 3000 Oe.

[0005] There is a close relationship between the coercive force Hc of the magnetic recording medium and the performance of the magnetic head.
Is too high, especially above 3000 Oe,
It is known that in a magnetic head that is widely used at present, the core is magnetically saturated due to a shortage of the saturation magnetic flux density Bm of the head core, so that the magnetic recording medium cannot be sufficiently magnetized. I have.

At present, ferrite heads are widely used in magnetic recording / reproducing devices corresponding to magnetic recording media having a coercive force of 1000 Oe or less, and magnetic recording / reproducing devices corresponding to magnetic recording media having a coercive force exceeding 1000 Oe. The head core is made of a material having a high saturation magnetic flux density, such as a sendust head, an amorphous head, and a thin film head.

Furthermore, the magnetic recording medium needs to have as large a reproduction output as possible at the time of high-density recording, and for that purpose, the perpendicular magnetization film is required to have as large a squareness ratio as possible.

Conventionally, as a perpendicular magnetization film for magnetic recording, C.I.
alloy films such as oCr alloys and CoPt alloys, and spinel-type oxide thin films such as cobalt ferrite (JP-A-51-1199)
No. 99, JP-A-63-47359, JP-A-Hei 3
-17813, JP-A-3-188604,
JP-A-4-10509, JP-A-5-12765) and magnetoplumbite-type oxide thin films such as barium ferrite (JP-A-62-267949) have been proposed.

Of the above-mentioned perpendicular magnetization films, cobalt ferrite (Co _x Fe
_{Since the 3-} XO ₄ ) film is an oxide, it is stable against oxidation, and has a large crystal magnetic anisotropy. Therefore, the film is promising as a perpendicular magnetic recording medium.

As is well known, cobalt ferrite (Co _X
Various methods such as a sputtering method, a vacuum evaporation method, and an MOCVD method are known as methods for producing the Fe _3-X O ₄ ) film.

In recent years, in order to improve the orientation of the perpendicular magnetization film, a single crystal is used as a substrate, or various underlayers are formed between the perpendicular magnetization film and the substrate.
Using MgO single crystal as substrate (IEEE T
rans. Mag. MAG-12 , No. 6,773
(1976), IEEE Trans. Mag. MAG
-14 , no. 5,906 (1978), Czehc
h. J. Phys. B21 , 563 (1971)) using NaCl as a substrate (J. Cry. Gro).
wth. 50 , 801 (1980)) and N as a base film.
Using iO (JP-A-5-166167)
Etc.

[0012]

A perpendicular magnetization film which is excellent in oxidation resistance and corrosion resistance and has a proper coercive force capable of avoiding magnetic saturation of a head which is widely used nowadays,
Although it is the most required at present, a material that sufficiently satisfies these properties has not yet been obtained.

That is, the known cobalt ferrite (C
If by _{o X Fe 3-X O 4} ) film sputtering method is mainly employed in the manufacturing method is generally cobalt ferrite _{(Co X Fe 3-X O} 4) perpendicular magnetization easy axis of the film (100) Despite the axis, there is a drawback that it is difficult to form a perpendicular magnetization film because it is randomly oriented or the (111) plane is easily oriented parallel to the base. Cobalt ferrite (Co _X ) whose (400) plane is preferentially oriented parallel to the substrate
Examples of the method of obtaining the Fe _3-X O ₄ ) film include the method described in the 9th Annual Meeting of the Japan Society of Applied Magnetics 29PB-10, and the method described in the 13th Annual Meeting of the Japan Society of Applied Magnetics, page 246. And the method described in JP-A-4-10509 are known.

The above-mentioned method is based on MgAl ₂ O ₄ ionized in Fe and Co in oxygen plasma and heated to 500 ° C.
It is a method of vapor deposition on a substrate or quartz glass, and it is necessary to maintain the substrate temperature at a high temperature of 500 ° C. or more in a vacuum during film formation, so that productivity is poor, and in order to raise the substrate temperature to 500 ° C. or more, The heat resistance of the substrate itself is required, but the heat resistance of glass, etc., which is currently widely used as a substrate material for perpendicular magnetic recording media, is insufficient, and the substrate material is limited. Absent.

The above-mentioned method is a plasma-excited MO-CV
D method, in which the substrate temperature is kept at 300 to 40 in vacuum during film formation.
Since it is necessary to maintain the temperature at 0 ° C., the productivity is poor,
Not economic.

In the above method, a metal multilayer film is formed by laminating two or more layers of Co and Fe, and then heat-treated at 500 ° C. or more in an atmosphere containing oxygen. Because of the necessity, the material of the base is limited, and it is not industrial or economical.

As the above-mentioned known base film, MgO single crystal or N
When aCl is used, the (400) plane of ferrite, which is a perpendicular magnetization film, is easily formed. However, since a single crystal substrate is expensive and easily cracked, and it is difficult to obtain a large-area one, it is practical. is not.

The NiO (200) oriented film as a base film can be easily formed on a glass substrate at room temperature by a sputtering method, and is practical for use as a base film. However, in the perpendicular magnetization film described in Japanese Patent Application Laid-Open No. 5-166167, the crystal orientation of the (400) plane is promoted by forming Co ferrite on the NiO base film. Since the (200) plane spacing (2.09 °) of the ground film is smaller than the (400) plane spacing (2.10 °) of Co _x Fe _3-X O ₄ , compressive stress acts on the magnetic film plane, and the vertical anisotropy is generated. There is a problem that the property is reduced.

This fact is because, as described in JP-A-3-17813, the perpendicular magnetic anisotropy of the ferrite layer increases when the lattice constant of the underlayer is larger than that of the ferrite layer. it is obvious.

Also, European Patent Application Publication No. 058
6142AI has been created on the surface of the substrate (1
The (400) plane formed on the NiO underlayer whose (00) plane is preferentially oriented parallel to the substrate has the (400) plane preferentially oriented parallel to the substrate.
o-containing γ-Fe ₂ O ₃ thin film, wherein Co and F
e is in the range of 0.10: 1 to 0.32: 1, the spacing between the (400) planes is 2.085 or less, and the light absorption coefficient at 700 nm of the film is 2.5 μm.
A perpendicular magnetization film having a ^{value of} m ^-1 or less is disclosed.

EP-A-058614
The perpendicular magnetization film disclosed in 2AI has a coercive force of 4000 Oe or more, and its technical problem is that it has excellent oxidation resistance and corrosion resistance and has a large coercive force, for example, when the coercive force is 4000 Oe or more. It is another object of the present invention to provide a perpendicular magnetization film having a large squareness ratio, a large Faraday rotation angle in a short wavelength region, and a small light absorption coefficient.

Accordingly, the present invention provides a spinel-type spinel type having excellent oxidation resistance and corrosion resistance, and having an appropriate coercive force, particularly, a coercive force of less than 3000 Oe and a large squareness ratio (value demagnetized). It is a technical object to industrially and economically manufacture a perpendicular magnetic film made of an oxide at a temperature as low as less than 500 ° C. as much as possible.

[0023]

The above technical object can be achieved by the present invention as described below.

That is, the present invention relates to a Co-containing maghemite thin film in which the (400) plane is preferentially oriented parallel to the surface of the substrate, wherein Co in the Co-containing maghemite thin film has a molar ratio of 0.01 or more to Fe. , Less than 0.10, and (4
A perpendicular magnetization film having a (00) plane spacing of 2.082 ° or less is formed on a NiO base film in which the (200) plane formed on the surface of the substrate is preferentially oriented parallel to the surface of the substrate. A maghemite thin film containing Co and Mn in which the (400) plane is preferentially oriented parallel to the surface of the substrate, wherein Co in the Co and Mn-containing maghemite thin film has a molar ratio of Fe to Fe. 0.01 or more, less than 0.10, Mn is 0.0
7 to 0.30, and the (400) plane spacing is 2.0
A perpendicular magnetic film of 82 ° or less is a magnetic recording medium in which a (200) plane formed on the surface of the base is formed on a NiO base film preferentially oriented parallel to the surface of the base.

The present invention also relates to a single-layer film made of Co-containing magnetite in which the (400) plane is preferentially oriented parallel to the surface of the substrate, or a multilayer film made of a magnetite layer and a CoO layer. Co is present in a molar ratio of 0.0 to Fe.
Forming a single-layer film or a multi-layer film having a thickness of 1 or more and less than 0.10 on a NiO base film whose (200) plane formed on the surface of the substrate is preferentially oriented parallel to the surface of the substrate,
A method for producing a magnetic recording medium comprising heat-treating at a temperature in the range of 240 to 450 ° C .; and a single-layer film or a magnetite layer made of a magnetite containing Co and Mn in which the (400) plane is preferentially oriented parallel to the surface of the substrate. A multilayer film comprising an oxide layer containing Co and Mn, wherein Co
Is 0.01 or more and less than 0.10 in molar ratio with respect to Fe, and Mn is in a molar ratio of 0.07 to 0.3 with respect to Co.
A single-layer film or a multilayer film, which is 0, is formed on a NiO base film whose (200) plane formed on the surface of the substrate is preferentially oriented parallel to the surface of the substrate, and then a temperature of 240 to 450 ° C. This is a method for producing a magnetic recording medium comprising heat-treating within a range.

Next, various conditions for implementing the present invention will be described.

The perpendicular magnetization film according to the present invention is a Co-containing maghemite thin film formed on the surface of a substrate via a NiO underlayer film (meaning a thin film containing a cobalt component in maghemite; the same applies hereinafter). And (40) of the thin film
0) The plane is preferentially oriented parallel to the surface of the substrate, and the plane spacing is 2.082 ° or less, and the molar ratio of Co in the thin film to Fe is 0.01 or more and less than 0.10, preferably Is 0.015 to 0.075, and more preferably 0.0
2 to 0.06. The coercive force of this thin film is 30
It is smaller than 00 Oe.

The "preferred orientation" in the present invention is defined by an area ratio of peaks on each surface measured by an X-ray diffractometer. That is, in the NiO underlayer, the ratio of the (200) plane peak area (S ₍₂₀₀₎ ) to the (111) plane peak area (S ₍₁₁₁₎ ) is 2 or more [S ₍₂₀₀₎ / S ₍₁₁₁₎ ≧ 2. ]
In a Co-containing maghemite film, a Co-containing magnetite film, a multilayer film composed of a magnetite layer and a CoO layer, and a multilayer film composed of a magnetite layer and an oxide layer containing Co and Mn, (311) (400) plane peak area (S) with respect to plane peak area (S ₍₃₁₁₎ )
₍₄₀₀₎ ) means 2 or more [S ₍₄₀₀₎ / S ₍₃₁₁₎ ≧ 2].

The Co-containing maghemite thin film of the present invention has a plane spacing of 2.082 ° or less, preferably 2.02 ° or less.
It refers to one of 65～2.082A, which Fe ²⁺ in magnetite which constitutes the multilayered film or a Co-containing magnetite film is completely become oxidized to Fe ³⁺ γ-Fe ₂ O _3, of course slightly Fe ²⁺ also remains.

When the (400) plane of the magnetic film is not preferentially oriented parallel to the surface of the base, the perpendicular magnetic film is not formed when the plane spacing of the (400) plane of the magnetic film exceeds 2.082 °. If the molar ratio of Co to Fe is less than 0.01, the film does not become a perpendicular magnetization film. In order to easily obtain a maghemite thin film in which the (400) plane is preferentially oriented parallel to the surface of the substrate, the thickness is preferably 0.02 or more. When Co exceeds 0.10 with respect to Fe, the coercive force exceeds 3000 Oe. When the spacing between (400) planes is less than 2.065, the coercive force is 3000O.
e may be exceeded.

The squareness ratio (corrected for demagnetizing field) of the perpendicular magnetization film according to the present invention is 0.88 or more, preferably 0.92 or more.
Above, more preferably 0.94 or more.

The perpendicular magnetization film according to the present invention may be provided, if necessary,
Mn may be contained in the Co-containing ghemite thin film. By containing Mn, a perpendicular magnetization film having an excellent squareness ratio (corrected for demagnetizing field), particularly having a squareness ratio of 0.1.
95 or more perpendicular magnetization films can be obtained.

The Mn content is 0.07 in mole with respect to Co.
To 0.30, preferably 0.10 to 0.20.
If the Mn content is less than 0.07 in molar ratio with respect to Co, the squareness ratio of the perpendicular magnetization film cannot be improved. Considering the squareness ratio, the upper limit of the amount of Mn is C
The molar ratio to o is 0.30, preferably 0.20.

The coercive force of the perpendicular magnetization film according to the present invention is 300
If it is larger than 0 Oe, it is impossible to avoid magnetic saturation of the magnetic head which is widely used at present. Considering the magnetic saturation of the magnetic head, the coercive force is more preferably 2500 Oe or less.

The perpendicular magnetization film according to the present invention comprises a magnetite FeO x .F formed on the surface of a substrate via an under film.
e ₂ O ₃ (0 <x ≦ 1) single-layer film or magnetite FeO
a multilayer film composed of an x.Fe ₂ O ₃ (0 <x ≦ 1) layer and a CoO layer, wherein the (400) plane of the single-layer film or the multilayer film is preferentially oriented parallel to the surface of the substrate, and Co in the film is F
It is manufactured by heat-treating a single-layer film or a multilayer film having a molar ratio of 0.01 to less than 0.10 with respect to e at 240 to 450 ° C.

The perpendicular magnetization film according to the present invention can
Mn may be contained in the Co-containing maghemite thin film. In the production, Co and M are used instead of the CoO layer.
A multilayer film in which an oxide layer containing n is formed is formed, and then heat treatment is performed similarly.

Magnetite FeO x F in the present invention
A multilayer film composed of an e ₂ O ₃ (0 <x ≦ 1) layer and a CoO layer is formed by a reactive sputtering method in which a metal target (an Fe target and a Co metal target) is sputtered in an oxygen atmosphere.
A direct method of forming an oxide film directly using a magnetite FeO x .Fe ₂ O ₃ (0 <x ≦ 1) sintered target and a sintered target of an oxide containing Co, and a metal (Fe) in an oxygen atmosphere. And Co and metals and alloys)
Can be obtained by any method of reactive vapor deposition. Further, when it is desired to produce the same product by increasing the deposition rate in the reactive sputtering method, the oxygen partial pressure may be increased.

In the present invention, the lower the oxygen partial pressure in forming a single-layer film composed of a Co-containing magnetite or a multilayer film composed of a maghemite layer and a CoO layer, the lower the obtained oxygen partial pressure becomes.
The spacing between the (400) planes of the o-containing maghemite thin film tends to be small.

In the present invention, the single-layer film or the multilayer film is made of Co
Is at least 0.01 and less than 0.10. When the molar ratio of Co to Fe is less than 0.01,
If any single-layer film or multilayer film in the case of 0.10 or more is used, the perpendicular magnetization film aimed at by the present invention cannot be obtained.

Since the multilayer film of the present invention is epitaxially grown on the NiO underlayer, the thickness of one cycle is 130.
Å Since the (400) plane is oriented parallel to the substrate,
The number of laminating operations can be reduced, which is industrially and economically advantageous. Experiments have confirmed that, in the case where there is no NiO base film, in order to obtain a perpendicular magnetization film, the thickness of one cycle needs to be 130 ° or less.

The perpendicular magnetization film according to the present invention is a multilayer film composed of a magnetite layer and a CoO layer formed on the surface of the substrate via an underlayer, and the (400) plane of the multilayer film is located on the surface of the substrate. By performing heat treatment at 240 to 450 ° C. on a multilayer film which is oriented in parallel and in which the molar ratio of Co in the multilayer film to Fe is 0.01 or more and less than 0.1 with respect to Fe, an underlayer is formed on the substrate. A Co-containing magnetite single-layer film formed in such a manner that the (400) plane of the single-layer film is oriented parallel to the surface of the substrate, and that the Co in the single-layer film has a molar ratio of 0.1 to Fe with respect to Fe.
A single-layer film having a temperature of 01 or more and less than 0.1 is heated to 240 to 450 ° C.
It is manufactured by heat treatment.

The perpendicular magnetization film according to the present invention can be obtained by any of a method of heat-treating a Co-containing magnetite and a method of heat-treating a multilayer film composed of a magnetite layer and a CoO layer. Since they can be grown independently without being inhibited by the growth of the crystal, they are more likely to be oriented (400) and are considered preferable.

The structural unit of one cycle of the multilayer film in the present invention may be composed of a magnetite layer-CoO layer or a magnetite layer-CoO layer-magnetite layer or a CoO layer-magnetite layer-CoO layer. It may be. In addition, in the order of formation, in the case of two layers of the magnetite layer and the CoO layer, either the CoO layer or the magnetite layer may be first.

Whatever the thickness of one cycle of the multilayer film,
The desired perpendicular magnetization film is obtained. The present inventor has confirmed that a target film can be obtained even when the thickness of one cycle is 1500 °.

The number of periods may be any one or more,
Since the thickness of the perpendicular magnetization film is practically 500 to 3000 °, the number of periods may be determined so as to have a desired thickness. For example, in the case of forming a film having a thickness of 1500 °, if the thickness of one cycle is set to 1500 °, the number of cycles becomes 1 and 1
If the thickness of the period is 750 °, it becomes 2.

EP-A-058614
According to 2AI, if the heat treatment temperature is lower than 280 ° C. or if the thickness of one cycle of the multilayer exceeds 800 ° C.
There is a description that the diffusion of o into γ-Fe ₂ O ₃ becomes insufficient and it becomes difficult to obtain a perpendicular magnetization film. However, in the present invention, since the molar ratio of Co to Fe is low, γ-
Diffusion into Fe ₂ O ₃ is facilitated, and the heat treatment temperature is 28
Even if the temperature is lower than 0 ° C., and the thickness of one cycle of the multilayer film is 80
Even if it exceeds 0 °, a desired perpendicular magnetization film can be obtained.

In the case of forming an oxide layer containing Co and Mn in the present invention, a metal target (Co metal, Mn metal, Co—Mn alloy or Co and Mn) is formed in an oxygen atmosphere.
reactive sputtering method for sputtering (n composite target)
Either a direct method of forming an oxide film directly with a sintered target of an oxide containing Co and Mn, or a reactive deposition method of depositing a metal (a metal or an alloy composed of Co and Mn) in an oxygen atmosphere may be used.

The heat treatment temperature of the magnetite single layer film or multilayer film in the present invention is 240 to 450 ° C. 240 ° C
If less than, the magnetite FeO x .Fe ₂ O
₃ Oxidation (gamma conversion) of (0 <x ≦ 1) and diffusion of Co and Mn into the maghemite thin film are not sufficient, and the perpendicular magnetization film aimed at by the present invention cannot be obtained. If the temperature is higher than 450 ° C., maghemite pregelatinization starts to occur, and the perpendicular magnetic film intended in the present invention cannot be obtained.

For the heat treatment, see, for example, JP-A-57-54.
As described in JP-A-309, the oxidation (γ-formation) temperature of magnetite FeO x .Fe ₂ O ₃ (0 <x ≦ 1) is reduced by containing Cu in the film. This method can be implemented in the present invention, and the same effect can be obtained. Further, in the heat treatment, the magnetite FeO x .Fe ₂ O ₃ (0 <x ≦ 1) is oxidized (gamma-ized) at 200 to 320 ° C.
The diffusion can be performed in two stages of diffusing Co or Mn at 40 to 450 ° C., and in this case, generation of cracks that are likely to occur during oxidation (gamma conversion) can be suppressed.

The NiO underlayer of the present invention has a thickness of 8 in order to sufficiently promote the (400) plane orientation of the magnetic film.
00 to 3000 °, more preferably 1200 °
~ 2400 °.

The NiO base film is formed as an oxide film directly by a reactive sputtering method in which a metal (Ni) target is sputtered in an oxygen atmosphere on a substrate maintained at a temperature of 100 ° C. or lower, or a sintered target of an oxide containing Ni. It can be prepared by either a direct method or a reactive vapor deposition method in which metal (Ni) is deposited in an oxygen atmosphere. If the temperature of the substrate exceeds 100 ° C., it becomes difficult for the (200) plane to be oriented parallel to the surface of the substrate. The temperature of the substrate may be 100 ° C. or lower, and a lower temperature is preferable within this range.

As the substrate in the present invention, a commonly used substrate material such as glass can be used.

[0053]

The most important point in the present invention is that the perpendicular magnetization film according to the present invention forms a NiO underlayer with (200) plane preferentially oriented parallel to the surface of the base on the base, and (4)
Co) -containing magnetite single-layer film with the (00) plane preferentially oriented parallel to the surface of the substrate, or a magnetite FeO x.
A multi-layer film of an Fe ₂ O ₃ (0 <x ≦ 1) layer and a CoO layer, wherein the molar ratio of Co in the film to Fe is 0.01 or more and less than 0.10 or A multi-layer film is formed, and then the obtained single-layer film or multi-layer film is 240 to 450
The perpendicular magnetization film thus obtained by heat treatment at a temperature of about 8000C has a coercive force of less than 3000 Oe and a large squareness ratio (a value corrected for the demagnetizing field), for example, 0.88 or more; And it is the fact that it is excellent in oxidation resistance and corrosion resistance.

Regarding the reason why the perpendicular anisotropy according to the present invention has a large perpendicular anisotropy in spite of using the NiO underlayer, the present inventor considers the plane spacing of the (400) plane of the Co-containing maghemite thin film. Is 2.082 ° or less, particularly 2.065 to 2.082 °, which is smaller than 2.09 ° which is the spacing between the (200) planes of the NiO underlayer, and as a result, a tensile stress acts in the magnetic film plane. I think it is because.

The reason why the perpendicular magnetization film according to the present invention can obtain an appropriate coercive force, particularly a coercive force smaller than 3000 Oe, is based on the fact that Co in the Co-containing maghemite thin film has a molar ratio of Fe to Fe. When the NiO underlayer is not present even when the NiO underlayer is not less than 0.01 and less than 0.10, even if the Co-containing maghemite thin film is formed via the NiO underlayer, the molar ratio of Co in the film to Fe is small. Since the coercive force does not become less than 3000 Oe in any case of 0.10 or more, the fact that the Co-containing maghemite thin film is generated via the NiO base film and that the Co in the magnetic film has a molar ratio to Fe This is considered to be due to a synergistic effect of being 0.01 or more and less than 0.10.

Also, the C generated through the NiO underlayer film
Co in the o-containing maghemite thin film is 0.01
As described above, even when the value is less than 0.10, (40)
0) The coercive force is 30 when the plane interval is less than 2.065.
Since it is 00 Oe or more, the present inventor believes that the plane spacing of the (400) plane of the Co-containing maghemite thin film also affects the value of the coercive force.

When changing from Fe ₃ O ₄ to γ-Fe ₂ O ₃ , there is almost no change in the crystal form. That is, Fe ₃
O ₄ is a cubic spi having a lattice constant of 8.3967 °
Neel (Ref. National Burea)
u of Standards, Monograph
25, Sec. 5, 31 (1967). ), Γ-Fe ₂
O ₃ is also a lattice constant of 8.350Å cubic spin
el (Ref. Haul and Shoon,
Z. phys. Chemie, 44 216-226
(1939). ). Cubic crystal form is (400)
Since the plane, (040) plane and (004) plane are equivalent, X
The peaks of these planes all appear at the same position in the line diffraction spectrum. Therefore, in the present invention, these planes are all described as (400) planes.

The NiO crystal is also of the Cubic type, and therefore, the (200) plane, the (020) plane, and the (002) plane are equivalent. Therefore, these planes are all described as (200) plane.

It should be noted that the fact that the plane spacing of the perpendicular magnetization film according to the present invention is small is not due to shrinkage of the substrate, but is due to the film itself. The (222) plane is oriented parallel to the substrate.
After forming an e ₃ O ₄ single layer film (2000 °), oxidation (γ)
The spacing between the (222) planes of the converted film is a bulk value of 2.4.
This was confirmed by the fact that the angle was 2.407 °, which was almost equal to 08 °.

The multilayer film of the present invention is formed on a substrate by (20
Since the 0) plane is formed via the NiO base film preferentially oriented in parallel with the surface of the base, the thickness of one cycle can be increased.

For this reason, the inventor of the present invention has proposed that a magnetite layer and a CoO layer or Co and M
It is considered that the oxide layer containing n grows epitaxially with the oxide layer.

The magnetic properties of the perpendicular magnetization film of the present invention are as follows: the coercive force is less than 3000 Oe, preferably 2500 Oe or less.
More preferably, 1000 Oe or more;
0 emu / cm ³ or more, preferably 300 emu / cm
³ or more, more preferably 310 emu / cm ³ or more; squareness ratio of 0.33 or more, preferably 0.40 or more; demagnetization-corrected squareness ratio of 0.88 or more, preferably 0.92 or more, more preferably 0 or more .94 or more;
000 Oe or more, preferably 6000 Oe or more.

[0063]

Next, the present invention will be described with reference to Examples and Comparative Examples.

The magnetic characteristics of the perpendicular magnetization film in the following Examples and Comparative Examples are described in "Vibration sample type magnetometer VSM-3".
S-15 "(manufactured by Toei Industry Co., Ltd.).

The X-ray diffraction spectrum of the thin film was measured with an X-ray diffractometer RAD-2A (manufactured by Rigaku Corporation). Measurement conditions were as follows: tube used: Fe, tube voltage: 40 kV, tube current:
20 mA, goniometer: wide-angle goniometer, sampling width: 0.010 °, scanning speed: 1.000 ° /
min, divergence slit: 1 °, scattering slit: 1 °, light receiving slit: 0.30 mm, and diffraction angle (2θ) of 40.
The area from 00 ° to 60.00 ° was measured.

The X-ray diffraction spectrum of the film of the present invention composed of the NiO underlayer and the Co-containing γ-Fe ₂ O ₃
The peak position of the (400) plane of the contained γ-Fe ₂ O ₃ ,
Since the peak position of the (200) plane of iO is very close,
These two peaks overlap. Therefore, in order to determine the area of the peak of the (400) plane of the Co-containing γ-Fe ₂ O ₃ is (400) of Co-containing γ-Fe ₂ O ₃ of X-ray diffraction spectrum of the film of the present invention the surface and NiO It is necessary to subtract the peak area of the NiO (200) plane from the peak area of the (200) plane.

Here, the area of the peak of the (200) plane of NiO was determined by the following two methods, and almost the same value was obtained by either method.

Method 1 When the NiO layer was formed, the X-ray diffraction spectrum of this layer was measured, and the area of the peak on the (200) plane was determined.

Method 2 The film of the present invention comprising the NiO underlayer and the Co-containing γ-Fe ₂ O _{3 is} immersed in concentrated hydrochloric acid at 80 ° C. for 30 seconds, taken out, washed with water and dried. Compared with Co-containing γ-Fe ₂ O ₃ , NiO
There because hardly soluble in acid, Co-containing γ-Fe ₂ O In this process
Only ₃ can be removed. The X-ray diffraction spectrum of the film thus obtained is measured, and the peak area of the (200) plane of NiO is determined.

The (40) of Co-containing γ-Fe ₂ O ₃
The 0-plane spacing is obtained by removing the X-ray diffraction spectrum of the NiO underlayer measured by the above method from the X-ray diffraction spectrum of the film of the present invention by arithmetic processing (manufactured by RINT), and obtaining the obtained Co-containing γ- (40) of the X-ray diffraction spectrum of Fe ₂ O ₃
0) It was determined from the peak position of the plane. The peak area of the (400) plane may be determined from the X-ray diffraction spectrum of Co-containing γ-Fe ₂ O ₃ obtained by this method.

Example 1 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of the X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane and the peak area of the (111) plane was 5 And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
The thickness of the ₃ O ₄ film is set to 158 °, the thickness of the NaCl type CoO film is set to 2 ° (Co corresponds to 0.02 in molar ratio to Fe), and the thickness of one cycle is set to 160 °. This process was repeated twice to obtain a multilayer film with each of the Fe ₃ O ₄ layer and the CoO film being 12 layers.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Was 8, and the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film is subjected to a heat treatment at 330 ° C. for 2 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
_{(311 )} ] was 5, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the (400) plane spacing was 2.075 °. This Co-containing γ-Fe ₂ O ₃
As a result of observing the magnetization curve of the film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are such that the saturation magnetization value is 340 emu / cm ³ and the coercive force value is 1150
e, squareness ratio is 0.37 (the demagnetized value is 0.9
2) The perpendicular anisotropy magnetic field was 5200 Oe, and it was confirmed that the film was a good perpendicular magnetization film.

Example 2 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film was formed as a base layer with a thickness of 2,000 Å.

As a result of X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area on the (200) plane to the peak area on the (111) plane was 20. And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
The thickness of the ₃ O ₄ film is set to 400 °, the thickness of the NaCl-type CoO film is set to 8 ° (the molar ratio of Co to Fe is 0.03), and the thickness of one cycle is set to 408 °. This process was repeated twice to obtain a multilayer film with six layers each of the Fe ₃ O ₄ layer and the CoO film.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Was 8, and the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film was subjected to a heat treatment at 330 ° C. for 2 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 5, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the spacing between the (400) planes was 2.072 °. This Co-containing γ-Fe ₂ O ₃
As a result of observing the magnetization curve of the film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are as follows: the saturation magnetization value is 335 emu / cm ³ , and the coercive force value is 20000
e, squareness ratio is 0.65 (the value after demagnetization correction is 0.9
3) The perpendicular anisotropy magnetic field is 7800 Oe, and it is recognized that the film is a good perpendicular magnetization film.

Example 3 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film was formed as a base layer with a thickness of 2,000 Å.

As a result of the X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area on the (200) plane to the peak area on the (111) plane was 10%. And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
The thickness of the ₃ O ₄ film is 300 °, the thickness of the NaCl-type CoO film is 14 ° (Co corresponds to 0.07 in molar ratio with respect to Fe), and the thickness of one cycle is 314 °. This process was repeated _four times to obtain a multilayer film by using each of the Fe ₃ O ₄ layer and the CoO film as four layers.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Is 14
And the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film was subjected to a heat treatment at 350 ° C. for 2 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 10, the (400) plane was preferentially oriented parallel to the substrate, and the spacing between the (400) planes was 2.082 °. As a result of observing the magnetization curve of the Co-containing γ-Fe ₂ O ₃ film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are such that the saturation magnetization value is 325 emu / cm ³ and the coercive force value is 2900O.
e, squareness ratio is 0.80 (the value after demagnetization correction is 0.9
4) The perpendicular anisotropy magnetic field is 10,000 Oe, and it is recognized that the film is a good perpendicular magnetization film.

Example 4 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane and the peak area of the (111) plane was 10%. And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
_An oxide containing Co and Mn having a thickness of 260 ° of the ₃ O ₄ film (Mn corresponds to a molar ratio of 0.24 to Co).
One cycle of the film was formed with a thickness of 4 °. The thickness of one cycle is 26
4 °, and the molar ratio of Co to Fe was 0.02. This operation was alternately repeated 20 times, and a multilayer film was obtained by using 10 layers each of an Fe ₃ O ₄ layer having a thickness of 260 ° and an oxide layer containing Co and Mn having a thickness of 4 °.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Was 6, and the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film was heat-treated at 350 ° C. for 1 hour in the air to prepare a Co—Mn-containing γ-Fe ₂ O ₃ film using a NiO film as a base layer.

The X-ray diffraction spectrum measurement of the obtained Co—Mn-containing γ-Fe ₂ O ₃ film showed that the ratio of the area of the (400) plane peak to the area of the (311) plane peak [S
₍₄₀₀₎ / S ₍₃₁₁₎ ] is 4, the (400) plane is preferentially oriented parallel to the surface of the substrate, and (400)
The spacing between the surfaces was 2.072 °. This Co-containing γ-
Observation of the magnetization curve of the Fe ₂ O ₃ film revealed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are as follows: saturation magnetization value is 330 emu / cm ³ , coercive force value is 1450 Oe, squareness ratio is 0.47 (demagnetizing field corrected value is 0.95), perpendicular anisotropic magnetic field 6,200 Oe, which is a good perpendicular magnetization film.

Example 5 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of measuring the X-ray diffraction spectrum of this NiO film, the ratio of the area of the peak of the (200) plane to the area of the peak of the (111) plane [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] was 4 And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
_An oxide containing Co and Mn with a thickness of the ₃ O ₄ film of 300 ° (Mn corresponds to a molar ratio of 0.10 with respect to Co.)
The film was formed with a thickness of 4 °, and one cycle was formed. The thickness of one cycle is 304 °, and the molar ratio of Co to Fe is 0.0%.
It was 2. This operation is alternately repeated 20 times to obtain 30
0Å thick Fe ₃ O ₄ layer and 4Å thick Co and Mn
Each of the oxide layers containing was made into 10 layers to obtain a multilayer film.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio of the area of the (400) plane peak to the area of the (311) plane peak [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] was obtained. Was 9, and the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film was heat-treated at 350 ° C. for 1 hour in the air to form a Co—Mn-containing γ-Fe ₂ O ₃ film using a NiO film as a base layer.

The obtained Co—Mn-containing γ-Fe ₂ O ₃ film was analyzed by X-ray diffraction spectrum to find that the ratio of the area of the (400) plane peak to the (311) plane peak area [S
₍₄₀₀₎ / S ₍₃₁₁₎ ] is 7, the (400) plane is preferentially oriented parallel to the surface of the substrate, and (400)
The plane spacing was 2.069 °. This Co-containing γ-
Observation of the magnetization curve of the Fe ₂ O ₃ film revealed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are as follows: saturation magnetization: 335 emu / cm ³ , coercive force: 1500 Oe, squareness ratio: 0.46 (demagnetization-corrected value: 0.96), perpendicular anisotropy 6100 Oe, which indicates that the film is a good perpendicular magnetization film.

Example 6 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of the X-ray diffraction spectrum measurement of this NiO film, the ratio of the area of the peak of the (200) plane to the area of the peak of the (111) plane [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] was 6 And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
The thickness of the ₃ O ₄ film is set to 280 °, the thickness of the NaCl-type CoO film is set to 4 ° (Co corresponds to 0.023 in molar ratio with respect to Fe), and the thickness of one cycle is set to 284 °. This process was repeated _three times to obtain a multilayer film with three layers each of the Fe ₃ O ₄ layer and the CoO film.

As a result of the X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Was 4, and the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film was subjected to a heat treatment at 330 ° C. for 2 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 3, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the spacing between the (400) planes was 2.070 °. This Co-containing γ-Fe ₂ O ₃
As a result of observing the magnetization curve of the film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are such that the saturation magnetization value is 330 emu / cm ³ and the coercive force value is 2980O.
e, squareness ratio is 0.79 (the value after demagnetization correction is 0.9
0), a perpendicular anisotropy magnetic field of 11,000 Oe, and it was confirmed that the film was a good perpendicular magnetization film.

Example 7 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane to the peak area of the (111) plane was 20. And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel type Fe was added at 150 ° C.
The thickness of the ₃ O ₄ film is 300 °, the thickness of the NaCl type CoO film is 4 ° (Co corresponds to 0.02 in molar ratio with respect to Fe), and the thickness of one cycle is 304 °. This process was repeated _four times to obtain a multilayer film by using each of the Fe ₃ O ₄ layer and the CoO film as four layers.

As a result of X-ray diffraction spectrum measurement, the obtained multilayer film had only a peak on the (400) plane, no peak on the (311) plane, and the (400) plane was preferentially oriented parallel to the surface of the substrate. Was.

The obtained multilayer film was subjected to a heat treatment at 300 ° C. for 2 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, only the peak of the (400) plane was absent, and the peak of the (311) plane was absent. The (400) plane was preferentially oriented in parallel to the surface of the substrate, and the (400) plane spacing Was 2.072 °. This Co-containing γ-F
As a result of observing the magnetization curve of the e ₂ O ₃ film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are as follows: the saturation magnetization value is 340 emu / cm ³ , and the coercive force value is 1
700 Oe, the squareness ratio was 0.56 (the demagnetizing field corrected value was 0.95), and the perpendicular anisotropy magnetic field was 7000 Oe.

Example 8 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of X-ray diffraction spectrum measurement, this NiO film had only the peak of the (200) plane, no (111) plane, and the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
The thickness of the ₃ O ₄ film is 1300 °, the thickness of the NaCl type CoO film is 16 ° (Co corresponds to 0.018 in molar ratio with respect to Fe), and the thickness of one cycle is 1316 °. Repeatedly, the Fe ₃ O ₄ layer and CoO
A multilayer film was obtained using each of the films as one layer.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Was 9, and the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film was subjected to a heat treatment at 330 ° C. for 2 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 6, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the (400) plane spacing was 2.072 °. This Co-containing γ-Fe ₂ O ₃
As a result of observing the magnetization curve of the film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are such that the saturation magnetization value is 330 emu / cm ³ and the coercive force value is
e, squareness ratio is 0.55 (the value after demagnetization correction is 0.9
2), a perpendicular anisotropy magnetic field of 6800 Oe, which indicates that the film is a good perpendicular magnetization film.

Example 9 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere consisting of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of X-ray diffraction spectrum measurement of this NiO film, the ratio of the area of the peak of the (200) plane to the area of the peak of the (111) plane [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] was 40. And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
The thickness of the ₃ O ₄ film is set to 80 °, the thickness of the NaCl-type CoO film is set to 1 ° (the molar ratio of Co to Fe is 0.02), and the thickness of one cycle is set to 81 °. This process was repeated twice to obtain a multilayer film by using each of the Fe ₃ O ₄ layer and the CoO film as 10 layers.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Is 10
And the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film was subjected to a heat treatment at 240 ° C. for 3 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 8, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the spacing between the (400) planes was 2.072 °. This Co-containing γ-Fe ₂ O ₃
As a result of observing the magnetization curve of the film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are such that the saturation magnetization value is 330 emu / cm ³ and the coercive force value is
e, squareness ratio is 0.51 (the demagnetized value is 0.9
0), the perpendicular anisotropy field was 6000 Oe, and it was confirmed that the film was a good perpendicular magnetization film.

Example 10 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on glass substrate at 80 ° C
r, a metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr, and an adhesion rate of 40 ° / min.
An O film was formed with a thickness of 1000 °.

As a result of X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane and the peak area of the (111) plane was 3 And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, at 200 ° C., an oxygen partial pressure of 0.
A Fe-Co alloy target is sputtered in an atmosphere composed of argon and oxygen at a pressure of 10 mTorr and a total pressure of 5 mTorr, and a Co-containing Fe ₃ O ₄ single-layer film having a thickness of 1000 ° is deposited at a deposition rate of 40 ° / min. As a result, C
o was 0.02 by mole ratio with respect to Fe. ) Formed. The input power during film formation was 300 W.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 3, and the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained single layer film was heat-treated at 330 ° C. for 2 hours in the air to form a Co-containing γ-Fe ₂ O ₃ film using a NiO film as a base layer.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 2.5, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the spacing between the (400) planes was 2.072 °. This Co-containing γ-Fe ₂
As a result of observing the magnetization curve of the O ₃ film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are as follows.
A saturation magnetization value of 300 emu / cm ³ and a coercive force value of 170
0 Oe, squareness ratio is 0.55 (the value after demagnetization correction is 0.8
9) The perpendicular anisotropy magnetic field is 7000 Oe, and it is recognized that the film is a good perpendicular magnetization film.

Comparative Example 1 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 on a glass substrate held at 200 ° C.
A metal (Fe) target is sputtered in an atmosphere of argon and oxygen at mTorr and a total pressure of 5 mTorr to form a spinel-type Fe ₃ O ₄ film as a first layer with a thickness of 62 ° at an adhesion rate of 40 ° / min. did.

Next, the shutter is rotated and a metal (Co)
The target was sputtered, and a NaCl-type CoO film was formed as a second layer with a thickness of 4 ° at an adhesion rate of 42 ° / min to make one cycle.

The thickness of one cycle is 66 ° and Co is F
The molar ratio to e was 0.09. This operation was alternately repeated 100 times to obtain a multilayer film with 50 layers each of the Fe ₃ O ₄ layer and the CoO film.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Was 5, and the (400) plane was preferentially oriented parallel to the substrate.

The obtained multilayer film was heat-treated at 350 ° C. for 2 hours in the air to form a Co-containing γ-Fe ₂ O ₃ film.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the (400) plane was preferentially oriented parallel to the substrate, and the spacing between the (400) planes was 2.077 °. As a result of observing the magnetization curve of the Co-containing γ-Fe ₂ O ₃ film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are as follows: a saturation magnetization value is 340 emu / cm ³ , and a coercive force value is 5300 O
e, squareness ratio is 0.81 (value demagnetized is 0.91)
And it was confirmed that the film was a good perpendicular magnetization film.

Comparative Example 2 High Frequency High Rate Sputtering System SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film was formed as a base layer with a thickness of 2,000 Å.

As a result of measuring the X-ray diffraction spectrum of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane to the peak area of the (111) plane was 8. ,
The (200) plane was preferentially oriented parallel to the surface of the substrate.

A cobalt ferrite single layer film having a thickness of 0.17 μm was formed thereon at 450 ° C.

In the obtained cobalt ferrite film, as a result of X-ray diffraction spectrum measurement, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the (400) plane spacing was 2.106 °. there were. The magnetic properties of the cobalt ferrite film are as follows: saturation magnetization value is 260 emu / cm ³ , coercive force value is 1500 Oe, squareness ratio is 0.30 (demagnetizing field corrected value is 0.84), and perpendicular anisotropic magnetic field is 4000 Oe. there were.

Comparative Example 3 High Frequency High Rate Sputtering Apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
At 120 ° C., on a glass substrate, an oxygen partial pressure of 0.11 mTorr
r, a metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr, and an adhesion rate of 40 ° / min.
An O film was formed with a thickness of 1000 °.

As a result of the X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane and the peak area of the (111) plane was 1 Met.

Further, spinel type Fe was added at 200 ° C.
The thickness of the ₃ O ₄ film is set to 158 °, the thickness of the NaCl type CoO film is set to 2 ° (Co corresponds to 0.02 in molar ratio with respect to Fe), and the thickness of one cycle is set to 160 °. This was repeated twice to obtain a multilayer film with eight layers each of the Fe ₃ O ₄ layer and the CoO film.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Is 1.
It was 5.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] is 1, and the spacing between (400) planes is 2.
075 °. As a result of observing the magnetization curve of the Co-containing γ-Fe ₂ O ₃ film, both the coercive force and the residual magnetization were larger in the plane, and the film was not a perpendicular magnetization film.

Comparative Example 4 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.10 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane and the peak area of the (111) plane was 8 And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel type Fe was added at 200 ° C.
The thickness of the ₃ O ₄ film is set to 240 °, the thickness of the NaCl type CoO film is set to 2 ° (Co corresponds to 0.012 in molar ratio with respect to Fe), and the thickness of one cycle is set to 242 °. This was repeated twice to obtain a multilayer film with five layers each of the Fe ₃ O ₄ layer and the CoO film.

The obtained multilayer film was subjected to a heat treatment at 330 ° C. for 2 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 5, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the spacing between the (400) planes was 2.064 °. This Co-containing γ-Fe ₂ O ₃
As a result of observing the magnetization curve of the film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are such that the saturation magnetization value is 330 emu / cm ³ and the coercive force value is 3300O.
e, squareness ratio is 0.82 (the demagnetized value is 0.9
2), the perpendicular anisotropy field was 11000 Oe.

Comparative Example 5 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane to the peak area of the (111) plane was 6. And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
The thickness of the ₃ O ₄ film is set to 280 °, the thickness of the NaCl-type CoO film is set to 20 ° (Co corresponds to 0.107 in molar ratio to Fe), and the thickness of one cycle is set to 300 °. This process was repeated _three times to obtain a multilayer film with three layers each of the Fe ₃ O ₄ layer and the CoO film.

As a result of X-ray diffraction spectrum measurement of the obtained multilayer film, the value of the ratio [S ₍₄₀₀₎ / S ₍₃₁₁₎ ] of the peak area of the (400) plane and the peak area of the (311) plane was obtained. Was 4, and the (400) plane was preferentially oriented parallel to the surface of the substrate.

The obtained multilayer film was heat-treated at 330 ° C. for 2 hours in the air to obtain a Co-containing γ-
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, the ratio of the peak area of the (400) plane to the peak area of the (311) plane [S ₍₄₀₀₎ / S
₍₃₁₁₎ ] was 3, the (400) plane was preferentially oriented parallel to the surface of the substrate, and the spacing between the (400) planes was 2.078 °. This Co-containing γ-Fe ₂ O ₃
As a result of observing the magnetization curve of the film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are such that the saturation magnetization value is 330 emu / cm ³ and the coercive force value is 4600O.
e, squareness ratio is 0.86 (the value after demagnetization correction is 0.9
4), the perpendicular anisotropy field was 18000 Oe.

Comparative Example 6 High-frequency high-rate sputtering apparatus SH-250H-T06
(Reaction sputtering method using Nihon Vacuum Co., Ltd.)
By setting the distance between the substrate and the target to 80 mm,
Oxygen partial pressure 0.11 mTorr on a glass substrate at room temperature,
A metal (Ni) target is sputtered in an atmosphere composed of argon and oxygen at a total pressure of 5 mTorr to form
At a deposition rate of Å / min, a NaCl type NiO film having a thickness of 1000 で was formed as a base layer.

As a result of X-ray diffraction spectrum measurement of this NiO film, the value of the ratio [S ₍₂₀₀₎ / S ₍₁₁₁₎ ] of the peak area of the (200) plane to the peak area of the (111) plane was 20. And the (200) plane was preferentially oriented parallel to the surface of the substrate.

Further, spinel-type Fe
The thickness of the ₃ O ₄ film is set to 320 °, the thickness of the NaCl-type CoO film is set to 2 ° (Co corresponds to 0.009 in molar ratio with respect to Fe), and the thickness of one cycle is set to 322 °. This process was repeated _four times to obtain a multilayer film by using each of the Fe ₃ O ₄ layer and the CoO film as four layers.

As a result of X-ray diffraction spectrum measurement, the obtained multilayer film had only the peak of the (400) plane, no peak of the (311) plane, and the (400) plane was preferentially oriented parallel to the surface of the substrate. Was.

The obtained multilayer film was subjected to a heat treatment at 300 ° C. for 2 hours in the air to obtain a Co-containing γ-layer having a NiO film as an underlayer.
An Fe ₂ O ₃ film was formed.

The obtained Co-containing γ-Fe ₂ O ₃ film was made of X
As a result of the line diffraction spectrum measurement, only the peak of the (400) plane was absent, and the peak of the (311) plane was absent. The (400) plane was preferentially oriented in parallel to the surface of the substrate, and the (400) plane spacing Was 2.072 °. This Co-containing γ-F
As a result of observing the magnetization curve of the e ₂ O ₃ film, it was confirmed that the film was a perpendicular magnetization film. The magnetic properties of the perpendicular magnetization film are as follows: the saturation magnetization value is 340 emu / cm ³ , and the coercive force value is 1
000 Oe, the squareness ratio was 0.23 (the demagnetizing field corrected value was 0.80), and the perpendicular anisotropic magnetic field was 3000 Oe.

[0163]

The perpendicular magnetization film according to the present invention is excellent in oxidation resistance and corrosion resistance due to being an oxide as shown in the above-mentioned embodiment, and has an appropriate coercive force, especially 300
Since it is a magnetic recording medium having a coercive force smaller than 0 Oe and a large squareness ratio (value after demagnetization correction), it is suitable as a magnetic recording medium for high-density magnetic recording.

Furthermore, according to the method for manufacturing a magnetic recording medium of the present invention, the thickness of one cycle in manufacturing a multilayer film can be increased, which is extremely advantageous industrially and economically.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 5/66 G11B 5/85

Claims (4)

(57) [Claims] 1. A Co-containing maghemite thin film having a (400) plane preferentially oriented parallel to the surface of a substrate, wherein Co in the Co-containing maghemite thin film has a molar ratio of 0.1 to Fe with respect to Fe.
A perpendicular magnetization film having a plane spacing of not less than 01 and less than 0.10 and a plane spacing of the (400) plane of 2.082 ° or less is formed on the surface of the base so that the (200) plane is parallel to the base surface. A magnetic recording medium formed on a preferentially oriented NiO underlayer. 2. A maghemite thin film containing Co and Mn whose (400) plane is preferentially oriented parallel to the surface of the substrate, wherein Co in the maghemite thin film containing Co and Mn is F
e in a molar ratio of 0.01 or more and less than 0.10, Mn
Is 0.07 to 0.30 in molar ratio with respect to Co,
A perpendicular magnetization film having a (400) plane spacing of 2.082 ° or less is formed on a NiO base film in which the (200) plane is preferentially oriented parallel to the base surface and the (200) plane is formed on the base surface. A magnetic recording medium. 3. A single-layer film made of Co-containing magnetite whose (400) plane is preferentially oriented parallel to the surface of the substrate or a multilayer film made of a magnetite layer and a CoO layer, wherein Co in the film is converted to Fe. 0.01 or more, 0.1
A single-layer film or a multilayer film having a thickness of less than 0 is formed on a NiO base film in which the (200) plane formed on the surface of the substrate is preferentially oriented parallel to the surface of the substrate, and then 240 to 450
2. The method for producing a magnetic recording medium according to claim 1, wherein the heat treatment is carried out in a temperature range of ° C. 4. A single-layer film composed of a magnetite containing Co and Mn with the (400) plane preferentially oriented parallel to the surface of the substrate or a multilayer film composed of a magnetite layer and an oxide layer containing Co and Mn. The molar ratio of Co in the film with respect to Fe is 0.01 or more and less than 0.10,
A single-layer film or a multilayer film in which n is 0.07 to 0.30 in molar ratio with respect to Co is formed on the surface of the base (2).
3. The method for manufacturing a magnetic recording medium according to claim 2, wherein the (00) plane is formed on a NiO base film whose orientation is preferentially parallel to the surface of the substrate, and then heat-treated at a temperature in the range of 240 to 450 ° C.