JPH09120527A - Metal thin-film magnetic recording medium and method of manufacturing the same - Google Patents

Abstract

(57) Abstract: A metal thin film type magnetic recording medium and a method for manufacturing the same are provided which can achieve a high coercive force and a low noise without imparting a minute roughness like a texture treatment. A NiP layer 22 formed on a substrate 21 of a medium substrate 2 is irradiated with ions of a low acceleration voltage to cause internal strain in the amorphous NiP layer 22, and then a base layer 4,
The magnetic layer 5 and the protective film 6 are sequentially stacked. As the ions to be irradiated, for example, argon ions, oxygen ions or nitrogen ions are used.

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 used for a magnetic disk device such as a hard disk.
More specifically, the present invention relates to a metal thin film magnetic recording medium having excellent magnetic characteristics and recording / reproducing characteristics and a method for manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 1, a metal thin film magnetic recording medium (1) used for a hard disk generally has an amorphous NiP layer on a non-magnetic substrate (21) made of Al alloy, glass or the like. On the medium substrate (2) on which (22) is formed, an underlayer (4) consisting essentially of Cr, a magnetic layer (5) consisting of a Co alloy or the like, and a protective film (6) such as carbon are sequentially formed and laminated. Is formed. Recently, along with the improvement of the recording density (linear recording density and track density) of the metal thin film magnetic recording medium, it is necessary to increase the recording resolution of the magnetic recording medium, and the magnetic characteristics are improved (especially, high coercive force). There is a demand for improved recording / reproduction characteristics (especially low noise). As a means for improving the coercive force of a magnetic recording medium by taking structural measures, there is a method of applying a texture to the NiP layer of the medium substrate. The texture is N by using wrapping tape and loose abrasive grains.
This is to form minute unevenness with a surface roughness Ra of 50 to 100 angstroms in the circumferential direction of the iP layer, and when the NiP layer is textured, anisotropy of internal strain is developed and Effective for improving coercive force. However, when the texture is applied, the formation of abnormal protrusions and the flatness of the medium substrate are deteriorated due to the texture treatment, and therefore the flying height of the magnetic head must be increased in order to avoid contact between the magnetic head and the magnetic recording medium. Further, the bit density increases due to the formation of scratches and the like due to the texture processing, and the recording density of the magnetic recording medium decreases. For this reason, recently, the required surface roughness tends to be small, and in order to reduce bit error defects caused by the substrate, stable head running in a low flying region, and improvement of the flatness of the medium substrate, There is also a demand for an ultra-smooth medium substrate in which the substrate is superfinished.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to produce a metal thin film magnetic recording medium and a magnetic thin film type magnetic recording medium capable of achieving high coercive force and low noise of a magnetic recording medium even in a super smooth medium substrate subjected to superfinishing. Is to provide a method.

[0004]

In order to solve the above problems, in the method of manufacturing a metal thin film magnetic recording medium of the present invention, a medium substrate (2) having an amorphous NiP layer (22) is formed. )
Then, ions are irradiated at a low accelerating voltage to generate strain inside the NiP layer (22), and then an underlayer (4), a magnetic layer (5) and a protective film (6) are sequentially laminated. Argon ions, oxygen ions, or nitrogen ions can be used as the irradiation ions. Here, “low accelerating voltage” means that the ions are in the NiP layer (2
2) An amorphous NiP layer with an accelerating voltage that can penetrate into
This means an accelerating voltage that does not crystallize (22), and when argon ions, oxygen ions or nitrogen ions are used, the range is preferably about 300 to 2000 V, and the ionic current is preferably about 30 to 150 mA.

The metal thin film type magnetic recording medium of the present invention is a medium substrate (2) in which an amorphous NiP layer (22) is formed on a non-magnetic substrate (21) and inside the NiP layer (22). Has a distortion caused by ion irradiation.

[0006]

According to the method of manufacturing a metal thin film magnetic recording medium of the present invention, the NiP layer (2) is provided to the NiP layer (22) of the medium substrate (2).
Since the ions are irradiated with an accelerating voltage that allows ions to penetrate into 2) and an accelerating voltage that does not crystallize the amorphous NiP layer (22), the amorphous property of the NiP layer (22) is impaired. Without this, strain is generated inside the NiP layer. The strain generated inside the NiP layer (22) causes internal strain in the underlayer (4) and the magnetic layer (5) laminated on the NiP layer (22), and as a result, the magnetic force in the in-plane direction of the magnetic layer is generated. Anisotropy is improved, coercive force of the magnetic recording medium is improved, and noise is reduced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The metal thin film type magnetic recording medium of the present invention is characterized in that an amorphous NiP layer (22) formed on a non-magnetic substrate (21) contains ions accelerated by a low acceleration voltage. Irradiation is performed to cause strain inside the NiP layer (22).

FIG. 1 shows a metal thin film type magnetic recording medium of the present invention.
The partial sectional view of (1) is shown. Recording medium of the present invention (1)
Is an underlayer (4), a magnetic layer (5) and a protective film (6) on a medium substrate (2) consisting of a substrate (21) and a NiP layer (22).
However, the layers are formed in this order. In FIG. 1, the NiP layer
(22), the underlayer (4), the magnetic layer (5) and the protective film (6) are formed symmetrically with respect to the substrate (21) so that writing / reading can be performed on both sides. It is also possible to form each layer only on one side and write / read only on one side.

The medium substrate (2) has an amorphous NiP layer (22) formed on an Al / NiP substrate or a glass substrate (21) by a sputtering method, a plating method, a vacuum deposition method or the like. Next, a medium substrate having a NiP layer (22)
(2) is irradiated with nitrogen ions accelerated at a low acceleration voltage. Ion irradiation is performed by hot cathode electron impact ion gun, RF
Excitation ion gun or ECR (Electron Cyclotron Reso
nance) Ion gun can be used. Amorphous Ni
When the P layer (22) is irradiated with ions of a low acceleration voltage, the NiP layer is
Ions penetrate to a position of several angstroms to several tens of angstroms inside the (22), and strain occurs inside the NiP layer (22). Due to the internal stress due to this strain, N
Strain occurs on the surface of the iP layer (22). The low accelerating voltage at the time of ion irradiation means that the ions penetrate at least from the surface of the NiP layer (22) to the inside, but due to heating at the time of ion implantation, N
The voltage is such that the iP layer (22) does not crystallize due to temperature rise. When the ions used are argon ions, oxygen ions, and nitrogen ions, the acceleration voltage is preferably in the range of 300V to 2000V.

Next, on the NiP layer (22) of the medium substrate (2), an underlayer (4), a magnetic layer (5) and a protective film (6) are formed by a known method such as sputtering, plating or vacuum deposition. 2) are sequentially deposited and laminated to produce a metal thin film magnetic recording medium (1).

[0011]

EXAMPLES Example 1 This example demonstrates that ion bombardment creates strain within the NiP layer. The medium substrate is A
l / NiP substrate (3.5inch-31.5mil)
Then, the surface is subjected to ultra-smoothness treatment to give a surface roughness of 5-6.
It was processed to have an angstrom and a flatness of 5 to 6 μm. Using a hot cathode electron impact type ion gun,
The iP layer was irradiated with nitrogen ions at a low acceleration voltage of 1000V. Next, the obtained medium substrate is subjected to about 26 in a known manner.
After heating at a temperature of 0 ° C., an underlayer (component is substantially Cr; layer thickness is about 600 Å) is formed by a sputtering apparatus, and a magnetic layer (component is Cr 10 in atomic% is used).
%, Ta6%, balance substantially Co; layer thickness is 400 Å, and then a protective film (component substantially C;
A film thickness of 120 angstroms) was formed to obtain a test magnetic disk (a). The bias voltage at the time of forming the underlayer and the magnetic layer is about -200V.

For comparison, a test magnetic disk (x) was prepared in which the NiP layer was not irradiated with ions. The procedure for producing the magnetic disk (x) is the same as that of the magnetic disk under test (a) except that the ions were not irradiated.

The results of X-ray diffraction measurement of the test magnetic disks (a) and (x) are shown in FIG. Referring to FIG. 2, it can be seen that the Cr (200) peak and the Co (110) peak of the disc (a) are shifted to the lower angle side by 2θ as compared with the disc (x).
In addition, the numerical value showing the strength of the vertical axis is an arbitrary unit (arbitrary uni
t). From this X-ray diffraction measurement result, the disk (a)
It can be seen that the Cr underlayer and the magnetic layer of Co alloy of (1) are subjected to a large amount of compressive strain as compared with the disk (x). It is presumed that this is because the strain generated in the NiP layer caused residual strain in the underlayer and the magnetic layer.

Example 2 In this example, it is clarified that the magnetic characteristics and the recording / reproducing characteristics of the magnetic recording medium are improved by the strain generated inside the NiP layer by the ion irradiation. In addition to the test magnetic disks (a) and (x) manufactured in Example 1, the NiP layer has 10
The magnetic recording characteristics and the recording / reproducing characteristics of the test magnetic disk (b) irradiated with oxygen ions at 00 V were measured. Table 1 shows the measurement results. In Table 1, Hc is a coercive force, Brd is a residual magnetic flux density, S is a squareness ratio, TAA is an output, SNm is a ratio of medium noise to signal strength, and Nm is medium noise.

[0015]

[Table 1]

As is apparent from Table 1, the test magnetic disks (a) and (b) according to the embodiments of the present invention have magnetic characteristics (compared with those of the test magnetic disk (x) which is a conventional magnetic recording medium. In particular, it can be seen that both the coercive force Hc) and the recording / reproducing characteristics (particularly the medium noise Nm) are improved.

Embodiment 3 In this embodiment, the relationship between the ion accelerating voltage and the coercive force is examined by changing the ion accelerating voltage by the hot cathode electron impact type ion gun. 300V and 1000 on NiP layer
Two medium substrates irradiated with nitrogen ions at an accelerating voltage of V,
Further, a Cr underlayer and a magnetic layer of Co ₈₄ Cr ₁₀ Ta ₆ were respectively formed on the medium substrate which was not irradiated with ions, and the test magnetic disks (c), (c) and (c) were produced. 300V and 10 for NiP layer
A magnetic underlayer and a magnetic layer of Co ₈₄ Cr ₁₀ Ta ₆ were formed on two medium substrates irradiated with oxygen ions at an accelerating voltage of 00 V and a medium substrate not irradiated with ions, respectively, and the magnetic disk under test (d) ( d) (d) was prepared. 300V and 1 for NiP layer
A magnetic underlayer and a magnetic layer of Co ₇₇ Cr ₁₃ Ta ₆ Pt ₄ were formed on two medium substrates irradiated with nitrogen ions at an acceleration voltage of 000 V and a medium substrate not irradiated with ions, respectively. ) (e) (e) was produced. 30 for NiP layer
Irradiated with oxygen ions at 0 V and 1000 V accelerating voltage 2
A magnetic underlayer and a magnetic layer of Co ₇₇ Cr ₁₃ Ta ₆ Pt ₄ were respectively formed on one medium substrate and a medium substrate which was not irradiated with ions, to fabricate test magnetic disks (f) (f) (f).

FIG. 3 shows the coercive force measurement results of the test magnetic disks (c) and (d), and FIG. 4 shows the coercive force measurement results of the test magnetic disks (e) and (f). Referring to the results of FIGS. 3 and 4, the coercive force of the magnetic disk irradiated with oxygen ions is slightly better than that of the magnetic disk irradiated with nitrogen ions, and it is more desirable to apply oxygen ions. Recognize. Also, when the ion acceleration voltage is 300 V, the ion acceleration voltage is about 10%, and the ion acceleration voltage is 1000% as compared with the case where the ion irradiation is not performed.
At V, an improvement in coercive force of about 20% is recognized as compared with the case where no ion irradiation is performed.

If the ion acceleration voltage becomes too high, the NiP amorphous layer may be crystallized, so it should not be too high. The ions for irradiating the NiP layer are not limited to the oxygen ions and the nitrogen ions described above, and ions smaller than the oxygen ions, such as hydrogen ions, can be used.

[0020]

As described above, the metal thin film type magnetic recording medium of the present invention has a higher coercive force than the conventional magnetic recording medium.
The noise is small. Moreover, since it does not have a minute roughness like the texture treatment, the medium substrate is super-finished so that there are no minute protrusions and the flatness is further improved, thus increasing the flying height of the magnetic head. The magnetic recording medium can be made smaller, and high-density recording superior to that of the conventional magnetic recording medium can be realized.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a metal thin-film magnetic recording medium.

FIG. 2 is a graph showing an X-ray diffraction result of a magnetic recording medium.

FIG. 3 is a graph showing the relationship between the coercive force and the type and acceleration voltage of ions to be irradiated.

FIG. 4 is a graph showing the relationship between coercive force and the type and acceleration voltage of ions to be irradiated.

[Explanation of symbols]

 (1) Metal thin film magnetic recording medium (2) Media substrate (21) Substrate (22) NiP layer (4) Underlayer (5) Magnetic layer (6) Protective film

Claims (3)

[Claims] 1. An underlayer on a medium substrate (2) having an amorphous NiP layer (22) formed on a non-magnetic substrate (21).
In a method of manufacturing a metal thin film magnetic recording medium in which (4), a magnetic layer (5) and a protective film (6) are sequentially laminated, a medium substrate (2) is irradiated with ions at a low acceleration voltage to make it amorphous. NiP layer (22)
After strain is generated inside the magnetic layer, the underlayer (4) and magnetic layer (5)
A method of manufacturing a metal thin film type magnetic recording medium, characterized in that a protective film (6) and a protective film (6) are sequentially laminated. 2. The manufacturing method according to claim 1, wherein the ions to be irradiated are argon ions, oxygen ions or nitrogen ions. 3. An underlayer on a medium substrate (2) having an amorphous NiP layer (22) formed on a non-magnetic substrate (21).
(4), a magnetic layer (5), and a protective film (6) are sequentially laminated in a metal thin film type magnetic recording medium, the NiP of the medium substrate (2)
The layer (22) is a metal thin film type magnetic recording medium characterized in that it has a strain generated by ion irradiation.