JPH0562144A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain an intrasurface magnetic recording medium which has an excellent intrasurface magnetic characteristic even when the substrate temperature is not raised and the film thickness of its magnetic layer is increased and can be suitably applied to a ridge type disk. CONSTITUTION:This magnetic recording medium is constituted of a Cr base layer and magnetic layer which are successively formed on a nonmagnetic substrate. The composition of the magnetic layer is expressed by (Co1 PtbBc)100-xOx and the atomic percentages a, b, c, and x are respectively set at a=100-b-c, 0<=b<=50, 0.1<=c<=30, and 0<x<=15. In addition, the film thickness of the Cr base layer is set at >=500Angstrom and the integrated intensity ratio i200/I110 of one Cr (110) peak to another Cr (200) peak in its X-ray diffraction image is set at I200/I110 <=0.16.

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, and more particularly to a magnetic recording medium for in-plane magnetic recording.

[0002]

2. Description of the Related Art CoNiCr, CoC have been used as magnetic materials for high density magnetic recording media, especially in-plane magnetic recording.
High coercive force materials such as rTa and CoPtCr have been reported. When a magnetic recording medium is formed using these materials, in order to obtain a high coercive force of about 1500 Oe or more, 1
Substrate heating at about 00 ° C to 300 ° C or several tens to several hundreds
It is necessary to apply a bias voltage of the order of V to the substrate.

Therefore, in this case, there is a problem that an inexpensive polyethylene terephthalate (PET) substrate having low heat resistance cannot be used as the substrate, and the manufacturing apparatus thereof is large-scaled.

A magnetic thin film as a perpendicularly magnetized film which solves such problems as the substrate temperature during film formation and has a sufficient saturation magnetic flux density and / or a high coercive force is disclosed in, for example, the applicant's application. JP-A-2-74012 and JP-A-274012
-73510. These are CoPt
BO system or CoPtBM ₁ O system (where M ₁ is T
i, Zr, V, Cr, etc.), which is a magnetic thin film and has excellent magnetic characteristics as a perpendicular magnetic recording medium, but is particularly useful as an in-plane magnetic recording medium, for example, a metal tape for contact printing. In-plane coercive force has not been obtained enough as a master tape for use in production.

On the other hand, the applicant of the present invention has previously disclosed Japanese Patent Laid-Open No. 3-8.
6915, CoPtBM ₂ O system (however, M
₍₂ is one or more of Ti, Zr, V, Cr ...) By obliquely depositing a magnetic thin film on the substrate, the substrate temperature during film formation is not increased and a relatively thick film is formed. We have proposed a magnetic recording medium capable of obtaining a high coercive force Hc, a high saturation magnetic flux density, and a high anisotropic magnetic field.
However, in this case, since the manufacturing method by oblique vapor deposition is adopted, it cannot be applied to a normal in-plane recording medium such as a rigid disc.

Furthermore, the applicant of the present invention previously disclosed in Japanese Unexamined Patent Publication No. 2-73.
No. 511, by providing a non-magnetic orientation control layer such as Ti, Zr, V, Cr ... As an underlayer of a CoPt-based magnetic thin film, it is possible to increase the film thickness of the magnetic layer without increasing the substrate temperature. Even in such a case, a medium exhibiting excellent magnetic characteristics is obtained as a perpendicular or in-plane magnetic recording medium. However, when Cr, which is generally used as a material having good adhesion, is used as the underlayer,
No longitudinal magnetic recording medium has been obtained.

[0007]

As described above, the present invention can obtain a sufficiently high in-plane coercive force without raising the substrate temperature and even when the film thickness of the magnetic layer is relatively large. It is an object of the present invention to obtain an in-plane magnetic recording medium using the known Cr as an underlayer.

[0008]

In a magnetic recording medium according to the present invention, a magnetic layer is provided on a non-magnetic support via a Cr underlayer. The composition formula of this magnetic layer is (Co _a Pt
_b B _c ) _100-x O _x , and its composition range is a = 1
00-b-c, 0 ≦ b ≦ 50, 0.1 ≦ c ≦ 30, 0 <
x ≦ 15 (where a, b, c, x are atomic%), the thickness of the Cr underlayer is 500 Å or more, and the Cr (110) peak and Cr (200) peak of the X-ray diffraction image are When the integrated intensity ratio I ₂₀₀ / I ₁₁₀ is I ₂₀₀ / I ₁₁₀ ≤0.
Select 16

[0009]

As described above, in the magnetic recording medium of the present invention, the magnetic layer is used as the magnetic layer described above.
As proposed in Japanese Patent Laid-Open No. 2-7351, the magnetic layer is formed by using a CoPtBO-based material.
As with the magnetic recording medium proposed in Japanese Patent Laid-Open No.
By providing the underlayer, there is an advantage that a high coercive force can be obtained without increasing the substrate temperature at the time of film formation and even with a relatively thick film thickness.

Further, particularly in the present invention, the film thickness is 500Å
The above Cr underlayer is provided, and the X-ray diffraction image of the Cr underlayer is provided.
Strong integration with (200) peak and Cr (110) peak
Degree ratio I ₂₀₀/ I₁₁₀I₂₀₀/ I₁₁₀Select ≦ 0.16
The in-plane coercive force of the
Thus, a magnetic recording medium could be constructed.

Generally, this Cr (110) peak intensity I
It is known that the larger the value of ₁₁₀ is, the larger the in-plane coercive force of the Co-based alloy magnetic layer is. Therefore, this C
It is considered that the larger the r (110) peak intensity I _{110, the} higher the in-plane coercive force obtained.

In the present invention, the thickness of the Cr underlayer is set to 5
By setting it to be 00Å or more, this Cr underlayer is deposited with appropriate crystallinity, and the crystallographic orientation is selected by selecting the peak intensity as described above to obtain a good in-plane magnetic recording medium. It is something that can be obtained. That is, since the peak intensity is obtained as a relative value, the integrated intensity ratio I ₂₀₀ / I ₁₁₀ between this peak intensity I ₁₁₀ and another reference peak intensity I ₂₀₀ is selected to be about 0.16 or less as described above. As a result, the magnetic recording medium can be constructed with a good in-plane coercive force.

[0013]

The magnetic recording medium according to the present invention will be described in detail below. In the magnetic recording medium according to the present invention, a magnetic layer is provided on a non-magnetic support via a Cr underlayer. The composition formula of this magnetic layer is represented by (Co _a Pt _b B _c ) _100-x O _x ,
The composition range is a = 100−bc, 0 ≦ b ≦ 50,
0.1 ≦ c ≦ 30, 0 <x ≦ 15 (however, a, b, c, x
Is atomic%). The Cr film thickness of the underlayer as above 500 Å, and its Cr (110) of the X-ray diffraction pattern peaks and Cr (200) integrated intensity of the peak ratio I _{20 0} / I ₁₁₀
Is selected as I ₂₀₀ / I ₁₁₀ ≦ 0.16.

Example 1 A slide glass substrate was used as a non-magnetic support, and a Cr underlayer having a thickness of 1000 Å was deposited on this substrate by a magnetron type sputtering device, and CoP was deposited thereon.
A tBO-based magnetic layer was deposited.

In this case, the film forming conditions of each layer are as follows: background vacuum degree is 1.3 × 10 ⁻⁴ Pa, slide glass substrate temperature is room temperature, and sputtering power is DC 30.
It was set to 0W.

The magnetic layer has a total sputtering gas pressure of 2.
0 Pa, the total gas flow rate is 50 SCCM, the oxygen partial pressure is 0.058 Pa, the gas is a mixed gas of Ar gas and oxygen gas, the target is a composition of Co ₆₈ Pt ₂₃ B ₉ (atomic%), the diameter is 10 cm, and the thickness is A 3 mm alloy target was used to form a film with a film thickness of 1000 Å.

On the other hand, the Cr underlayer uses only Ar gas, the Ar gas flow rate is 100 SCCM, and the diameter is 10
cm Cr (99.99%) was used as the target.

At this time, the sputtering gas for the Cr underlayer is used.
The integrated pressure ratio I ₂₀₀/ I₁₁₀Change
And measure the change in the magnetic properties of the magnetic layer against this.
It was The result is shown in FIG. In Figure 1, each side
Inner coercive force on line a, squareness ratio on line b, coercive force squareness ratio on line c
Therefore it showed.

[0019] As can be seen from Figure 1, plane coercivity of the magnetic layer, squareness ratio and coercivity squareness ratio is dependent on the integrated intensity ratio I ₂₀₀ / I ₁₁₀ of the Cr underlayer, the integrated intensity ratio I ₂₀₀ / I
_In the range where ₁₁₀ is about 0.16 or less, 1300 Oe
The above-mentioned in-plane coercive force Hc could be obtained, and magnetic characteristics suitable for an in-plane high density magnetic recording medium could be obtained.

For reference, FIG. 2 shows an example of the X-ray diffraction image. In FIG. 2, peak p ₂₀₀ shows a Cr (200) peak, peak p ₁₁₀ shows a Cr (110) peak, and the other peaks are peaks of the magnetic layer above this.

Next, the dependence of the magnetic characteristics of the magnetic layer on the thickness of the Cr underlayer was examined. In each example, each layer was deposited on a non-magnetic support such as a slide glass substrate by a magnetron sputtering device and measured in the same manner as in Example 1 described above.

Example 2 In this example, the thickness of the Cr underlayer is 500 Å,
Other materials for the Cr underlayer and the magnetic layer, and the film forming conditions were selected in the same manner as in Example 1 described above to manufacture a magnetic recording medium.

Comparative Example 1 In this example, the thickness of the Cr underlayer is 100 Å,
Other materials for the Cr underlayer and the magnetic layer, and the film forming conditions were selected in the same manner as in Example 1 described above to manufacture a magnetic recording medium. Comparative Example 2 In this example, a magnetic layer was directly deposited on a non-magnetic support and the oxygen partial pressure during deposition was set to 0.035 Pa. Other magnetic layer materials and deposition conditions were used. Was selected in the same manner as in Example 1 above to manufacture a magnetic recording medium.

Table 1 shows the in-plane coercive force, squareness ratio and coercive force squareness ratio of the magnetic layers in Example 2 and Comparative Examples 1 and 2 described above.

[Table 1]

As can be seen from Table 1, when the thickness of the Cr underlayer is 500 Å, good in-plane coercive force, that is, 1300 O
A coercive force of about e or more is obtained, and the squareness ratio is 0.8 or more and the coercive force squareness ratio is 0.8 or less, and good in-plane magnetic characteristics are obtained.

3 and 4 show the in-plane magnetization polarities of the magnetic layers according to Example 2 and Comparative Example 2 described above. It can be seen that the intended in-plane magnetized film is obtained by providing the Cr underlayer and selecting the film thickness appropriately.

The above-mentioned magnetic properties were measured by a sample vibrating magnetometer, and the X-ray diffraction image was analyzed using Cu-Kα rays.

Further, the magnetic recording medium of the present invention comprises
In addition to the composition and film thickness shown in Examples 1 and 2,
Various composition, film thickness and integrated intensity ratio I₂₀₀
/ I ₁₁₀Good longitudinal magnetic recording medium even when
Can be obtained.

[0029]

As described above, in the present invention, C
By adopting the configuration in which the oPtBO-based magnetic layer is provided via the Cr underlayer, good magnetic characteristics can be obtained without increasing the substrate temperature as in the conventional case, and even if the thickness of the magnetic layer is large, particularly Cr The thickness of the underlayer is set to 500 Å or less, and the crystal orientation is further calculated by the integrated intensity ratio I ₂₀₀ / I _110.
Was selected to be 1.6 or less, it was possible to obtain an in-plane magnetic recording medium having a high in-plane coercive force, which is suitable for a high-density recording medium.

In the case of the present invention, a good in-plane coercive force can be obtained without adopting a manufacturing method by oblique vapor deposition, so that the present invention can be applied to a magnetic recording medium such as a rigid type disk, and cannot be realized conventionally. An in-plane magnetic recording medium could be obtained by using a Cr material having good adhesion as the underlayer.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an integrated intensity ratio I ₂₀₀ / I _{110 of a} Cr underlayer and magnetic characteristics of a magnetic layer.

FIG. 2 is a diagram showing X-ray diffraction images of a Cr underlayer and a magnetic layer.

FIG. 3 is a diagram showing an in-plane magnetization curve of an example of the magnetic recording medium of the present invention.

FIG. 4 is a diagram showing an in-plane magnetization curve of a comparative magnetic recording medium.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Aso 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (1)

[Claims] 1. A magnetic layer is provided on a non-magnetic support via a Cr underlayer, and the composition formula of the magnetic layer is (Co _a Pt _b B _c ).
Indicated by _100-x O _x, the composition range is as a = 100-b-c 0 ≦ b ≦ 50 0.1 ≦ c ≦ 30 0 <x ≦ 15, the thickness of the Cr underlayer 500Å The integrated intensity ratio I ₂₀₀ / I ₁₁₀ between the Cr (110) peak and the Cr (200) peak in the X-ray diffraction image is set to I ₂₀₀ / I ₁₁₀ ≤0.16. Magnetic recording medium.