JP3520751B2 - Perpendicular magnetic recording medium, method of manufacturing the same, and storage device using the same - 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 mounted in a magnetic disk device or a magnetic tape device mainly used as an external storage device of a computer, and more particularly to a thin film type magnetic recording excellent in perpendicular magnetic characteristics. The present invention relates to a medium, a method for manufacturing the medium, and a storage device incorporating the medium.

[0002]

2. Description of the Related Art Recently, the progress of high density recording in the field of magnetic recording is extremely rapid, and there is an increasing demand for a recording medium having a shorter wavelength recording / reproducing characteristic. Currently used magnetic tapes and magnetic disks are all so-called in-plane magnetized films having magnetic anisotropy in the in-plane direction of the film.
Although various improvements have been made in order to cope with higher densities, the in-plane magnetized film has an essential demagnetizing field that increases as the recording density increases, resulting in a decrease in reproduction output. I have a problem.

On the other hand, a so-called perpendicular magnetization film having magnetic anisotropy in the direction perpendicular to the film surface has a small demagnetizing field even in short wavelength recording, and is therefore more suitable for high density recording than the in-plane magnetization film. It is said that CoCr, CoCrTa, CoO and the like have been developed as materials for forming such a perpendicular magnetization film. Most of the perpendicularly magnetized films are formed by a sputtering method, but there are also films such as a CoO film formed by an evaporation method with high production efficiency. This CoO film is formed directly on a non-magnetic substrate, and when a cobalt oxide layer, that is, a CoO layer is formed as a base film,
It is reported that it is formed on it. Especially, C
It has been reported that when a CoO magnetic layer is formed on an oO underlayer, both the crystallinity and the perpendicular magnetic properties are improved (Takanobu Takayama an.
d Kazuetu Yoshida, J .; Magn.
Soc. Jpn. , Vol. 15, No. S2,100
7 (1991)).

[0004]

However, looking at the magnetic characteristics in the above reports, the ratio of the remanent magnetization in the perpendicular direction to that in the in-plane direction is almost 1, so that the perpendicular magnetic orientation is sufficient. There is a problem that I cannot say.

[0005]

In order to solve the above-mentioned problems, the present inventor has found that, particularly, in a perpendicular magnetic recording medium provided with an underlayer made of cobalt oxide and a magnetic layer containing cobalt as a main component, As a result of various studies focusing on the relationship between the saturation magnetization amount of the layer and the coercive force in the vertical direction, and the relationship between the saturation magnetization amount and the vertical orientation ratio, in the range of the specific saturation magnetization amount in the vertical direction , It has been found that both the coercive force and the vertical orientation ratio are improved.

[0006] That is, according to the present invention, the magnetic layer of the base layer and the cobalt consisting cobalt oxide on a nonmagnetic substrate mainly vertical magnetic layer of the perpendicular magnetic recording medium formed by laminating in this order Direction saturation magnetization is 300-
600 emu / cc range and vertical protection
A magnetic material having a magnetic force of 1000 Oe or more is provided. Further provided is a method of manufacturing a perpendicular magnetic recording medium, which includes a step of forming both the underlayer and the magnetic layer by a vacuum deposition method. A storage device incorporating such a perpendicular magnetic recording medium is also provided. In each of the above configurations, CoO is preferable as the material for forming the underlayer, and Co or Co alloy is the main component as the material for forming the magnetic layer, and oxygen is contained therein. preferable.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The perpendicular magnetic recording medium of the present invention comprises a non-magnetic substrate on which an underlayer made of cobalt oxide and a magnetic layer containing cobalt as a main component are laminated. The magnetization amount (Ms) is in the range of 300 to 600 emu / cc. The saturation magnetization of this magnetic layer is 30
If it is less than 0 emu / cc, the coercive force in the perpendicular direction will decrease, and if it exceeds 600 emu / cc, the perpendicular magnetic orientation will deteriorate.

As the non-magnetic substrate, besides glass, a polymer film such as polyethylene terephthalate (PET) or a metal substrate such as aluminum can be used. As the cobalt oxide forming the underlayer, CoO
It is preferable that the magnetic layer contains cobalt or a cobalt alloy as a main component and contains oxygen. As the cobalt alloy, for example, Co containing nickel (Ni), chromium (Cr), etc. can be cited, and the hexagonal close-packed structure (HC) of Co (HC
Other elements may be contained as long as P) is not destroyed. The film thickness of the underlayer and the magnetic layer is not particularly limited, but for example, the underlayer has a thickness of 100 to 8
00A (Angstrom: same below), 60 magnetic layer
It is preferably in the range of 0 to 3000A.

Next, a method of manufacturing the perpendicular magnetic recording medium of the present invention will be described. A base layer and a magnetic layer are sequentially formed on a non-magnetic substrate using a vacuum deposition method. In particular,
As an evaporation source, for example, Co is arranged in the vacuum chamber, and an ejection port for oxygen gas is arranged at a predetermined distance from the substrate.
A CoO film is formed on the substrate by heating and evaporating Co by, for example, an electron beam while introducing oxygen gas into the vacuum chamber at a predetermined flow rate. In particular, in the step of forming the magnetic layer, the saturation magnetization amount Ms of the obtained magnetic layer is determined by the oxygen gas flow rate to be introduced, so that the oxygen gas flow rate is set so that the Ms value in the specific range described above is obtained. It is necessary to adjust According to such a process, the base film and the magnetic layer can be continuously formed only by changing the flow rate of the introduced oxygen gas, which is extremely useful for improving the productivity.

Further, the storage device of the present invention is obtained by incorporating the above perpendicular magnetic recording medium into an external storage device such as an HDD, and has excellent coercive force in the vertical direction and perpendicular magnetic orientation. It is a thing.

<Example> (Example 1) Using a vapor deposition apparatus having an electron beam, the vacuum was evacuated to an ultimate vacuum of 1 x 10 ^-7 Torr. A glass substrate having a thickness of 0.9 mm was used as a substrate, and the glass substrate was set directly above 330 mm from the evaporation source. Co (purity 3N) was used as the evaporation source. Oxygen gas ejection port 10m from the substrate
It was arranged at the position of m. First, when forming the underlayer, Co is heated and evaporated by an electron beam while introducing oxygen gas at a flow rate of 5 sccm to form CoO to a thickness of 480 A.
It was used as a base layer. The substrate was not heated in this step. Subsequently, the oxygen gas flow rate was reduced to 2 sccm, and Co was similarly heated and evaporated to form a magnetic layer made of a ferromagnetic metal thin film having a film thickness of 1600A.

The sample thus produced was cut into a size of 9 × 9 mm, and its magnetic characteristics were measured by a vibrating sample magnetometer (VSM) with a maximum applied magnetic field of 10 kOe. The measurement was performed in two directions: when a magnetic field was applied to the sample film surface and when it was applied in a direction perpendicular to the sample film surface. The vertical orientation ratio is the squareness ratio R in the direction perpendicular to the film surface.
s per. And the in-plane direction squareness ratio Rs plan. It was evaluated by calculating the ratio with. This vertical orientation ratio R
s per. / Rs plan. When the value is 1 or more, the magnetic orientation is in the vertical direction, and it can be said that the larger this value, the better the vertical orientation. As a result, the saturation magnetization amount Ms of the sample obtained above is 466 emu / c
c, vertical orientation ratio Rs per. / Rs plan. =
1.24, and the coercive force in the vertical direction Hc per. =
It was 1400 Oe.

Example 2 Samples of various Ms were carried out in the same manner as in Example 1 except that the flow rate of introduced oxygen gas when forming the magnetic layer was changed in the range of 1.5 sccm to 2.5 sccm. Was produced. As described above, the Ms of the magnetic layer is variously changed, that is, the Ms of the magnetic layer of the present invention is in the range of 300 to 600 emu / cc. Samples including those that were out of alignment were prepared, and the coercive force Hc per. And vertical orientation ratio Rs per. / Rs plan. Of the Ms and Hc per. , And Ms and Rs per. / Rs plan. 1 and 2 respectively.

As is clear from these figures, the magnetic layer having Ms in the range of 300 to 600 has Hcp.
er. Is as high as 1,000 (Oe) or more, and the vertical orientation ratio Rs per. / Rs plan. Was 1 or more, and it was found that the perpendicular magnetic orientation was good. on the other hand,
When Ms is less than 300 emu / cc, the vertical alignment property is good, but Hc per. When Ms exceeds 600 emu / cc, Hc
per. Was relatively good, but it was confirmed that the vertical alignment property was deteriorated. Further, in the above example, a sample was prepared in the same manner as above except that the film thickness of the CoO underlayer was changed to 230A and 725A, and the same measurement was performed. As a result, the same tendency as in FIGS. 1 and 2 was obtained. showed that.

[0015]

As described above in detail, according to the present invention, by setting the saturation magnetization amount of the magnetic layer in the optimum range, the perpendicular orientation is good and the perpendicular magnetic field has a high coercive force. A recording medium can be obtained, and as a result, higher density can be achieved. Further, according to the manufacturing method of the present invention, such a perpendicular magnetic recording medium can be efficiently manufactured by using the vacuum deposition method.

[Brief description of drawings]

FIG. 1 is a saturation magnetization Ms and a coercive force Hc pe in the perpendicular direction.
r. It is a graph which shows the relationship with.

FIG. 2 shows the saturation magnetization Ms and the vertical orientation ratio Rs per. /
Rs plan. It is a graph which shows the relationship with.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 5/66 G11B 5/85

Claims (5)

(57) [Claims] 1. A non-magnetic undercoat layer formed of cobalt oxide on a substrate and cobalt magnetic layer mainly perpendicular magnetic recording medium formed by laminating in this order, the saturation magnetization in the vertical direction of the magnetic layer The amount is 300-600 emu
/ Cc and the vertical coercive force is 100
A perpendicular magnetic recording medium characterized by being 0 Oe or more . 2. The perpendicular magnetic recording medium according to claim 1, wherein the underlayer is made of CoO. 3. The perpendicular magnetic recording medium according to claim 1, wherein the magnetic layer contains cobalt or a cobalt alloy as a main component and further contains oxygen. 4. The method according to claim 1, including a step of forming the underlayer and the magnetic layer by a vacuum deposition method.
6. A method of manufacturing a perpendicular magnetic recording medium according to claim 6. 5. A storage device incorporating the perpendicular magnetic recording medium according to claim 1. Description: