JPS63201913A - Perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To permit formation of a perpendicularly magnetized film having excellent perpendicular coercive force even if a Co-Cr layer is prepd. at a low temp. by providing a 'Permalloy(R)' film as a high magnetic permeability film to the lower part of the Co-Cr layer contributing to recording and reproduction as the perpendicularly magnet ized film in such a manner that the half-amplitude level of the locking curve indicating the perpendicular orientability of the film plane of the <111> axis of the face-centered cubic structure on a nonmagnetic base attains >=9 deg.. CONSTITUTION:The 'Permalloy(R)' film 2 having >=9 deg. half-amplitude level (DELTAtheta50) of the locking curve indicating the perpendicular orientability of the film plane of the <111> axis in the face-centered cubic structure (fcc structure) is formed on the nonmagnetic base 1 and the perpendicularly magnetized Co-Cr film 3 is formed thereon. If the DELTAtheta50 of the 'Permalloy(R)' film 2 is >=9 deg. as mentioned above, the perpendicular coercive force of the perpendicularly magnetized film 3 of the perpendicular magnetic recording medium can be increased to >=4,000e and the magnetic characteristics effec tive as the perpendicularly magnetized film 3 of the perpendicular magnetic recording medium are obtd. Namely, the high perpendicular coercive force and excellent reproduc tion output are obtd. and the high-density magnetic recording is executed even if the Co-Cr layer 3 is prepd. at the low temp.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a perpendicular magnetic recording medium suitable for high-density magnetic recording, and in particular a perpendicular magnetic recording medium having a double-layer structure consisting of a high magnetic permeability film and a perpendicular magnetization film. This is an attempt to improve the magnetic properties of perpendicular magnetic recording media.

[Summary of the invention]

The present invention provides a perpendicular magnetic recording medium with a double-layer structure suitable for high-density magnetic recording, in which a <111> axis of a face-centered cubic structure (hereinafter referred to as an FCC structure) is oriented perpendicular to the film plane on a non-magnetic support. A permalloy film with a rocking curve half-width (hereinafter referred to as Δθ5°) of 9° or more is formed on the permalloy film.
By forming an r-based perpendicularly magnetized film, we aim to provide a perpendicular magnetic recording medium that has a large perpendicular coercive force even when the perpendicularly magnetized film is produced at a low temperature, has excellent reproduction output, and is suitable for achieving high-density magnetic recording. It is something to do.

[Conventional technology]

In recent years, improvements in recording density due to shorter wavelengths and narrower tracks in magnetic recording have been remarkable, and the practical application of areal recording densities close to those of optical recording has been achieved through the use of so-called perpendicularly magnetized films, which can magnetize perpendicularly to non-magnetic supports. This is expected to be achieved by using perpendicular magnetic recording media.

Such perpendicular magnetic recording media can perform recording and reproduction at a recording wavelength of 0.5 μm or less by performing recording and reproduction using an auxiliary magnetic pole excitation type vertical head. Also, recently, perpendicular magnetic recording media using a normal ring-type head have been proposed. In this case, it is necessary that the perpendicular coercive force of the perpendicular magnetization film used in the perpendicular magnetic recording medium is extremely large, but it is necessary to achieve good recording and reproducing performance similar to when using an auxiliary pole excitation type vertical head. It is possible to

From the viewpoint of improving the recording efficiency and reproduction sensitivity of the magnetic recording medium used for perpendicular magnetization recording as described above, for example, perpendicular magnetization H, (e.g. Co-Cr-based perpendicular magnetization film, hereinafter Co-CrN) is deposited on a non-magnetic support. Among them, a perpendicular double-layered structure in which a high magnetic permeability film (hereinafter referred to as permalloy film) is provided between the non-magnetic support and the perpendicularly magnetized film has been proposed. Magnetic recording media are attracting attention.

Even when the perpendicular magnetic recording medium has a two-layer structure as described above, the reproduction sensitivity can be further improved by increasing the perpendicular coercive force of the Go--Cr layer used as the perpendicular magnetic recording layer. G above.

It is known that in order to increase the perpendicular coercive force of the -Cr layer, it is better to set the temperature conditions at high temperature when producing the Co--Cr layer.

Therefore, as a means to increase the perpendicular coercive force of the Co-Cr layer, a conventional method has been proposed in which the temperature of the non-magnetic support is set to a high temperature when the Co-Cr layer is fabricated by sputtering or vacuum evaporation. has been done.

However, in the above method, for example, polyethylene terephthalate (hereinafter referred to as PE), which is a type of polyester film, is used.
When using a material that has very excellent properties as a non-magnetic support for perpendicular magnetic recording media such as T) film but has poor heat resistance, the heat resistance of the non-magnetic support may When producing a perpendicular magnetic recording medium, the temperature applied to the nonmagnetic support is limited, and the temperature cannot be made too high. Therefore, the Co-Cr layer must be produced at a low temperature, so the above-mentioned co The perpendicular coercive force of the -Cr layer is not very large, and the reproduction output is also low, resulting in poor magnetic properties as a perpendicular magnetic recording medium for achieving high-density magnetic recording.

[Problem that the invention seeks to solve]

The perpendicular coercive force of the Co-Cr layer of a double-layered perpendicular magnetic recording medium was a large value obtained from the temperature of the nonmagnetic support when the Co-Cr layer was fabricated, but Compared to the perpendicular coercive force of the Co--Cr layer, it is not sufficient to achieve high-density magnetic recording, and in terms of the allowable temperature limit of the nonmagnetic support.

There was a problem in producing the -Cr layer at high temperature.

Therefore, it is an object of the present invention to provide a perpendicular magnetic recording medium that has a large perpendicular coercive force even when a Co--Cr layer is produced at a low temperature, has excellent reproduction output, and is suitable for achieving high-density magnetic recording.

[Means for solving problems]

The inventors have proposed that co-Cr
As a result of detailed study on the method of forming a two-layer structure by providing a permalloy film as a base layer on a layer, it was found that the fcc structure of the permalloy film used as a base layer of a Co-Cr layer is <1
It has been found that the degree of orientation perpendicular to the film surface of the 11> axis affects the perpendicular coercive force of the Co--Cr layer. In other words, when producing co-crm at low temperatures, we obtained the knowledge that if the permalloy film is formed in a direction that deteriorates the degree of perpendicular orientation of the Il1 plane, the perpendicular coercive force of the Co-Cr layer formed on top of the permalloy film will improve. Ta.

The present invention was made based on the above-mentioned findings, and Δθ represents the degree of orientation perpendicular to the film surface of the <111> axis of the fcc structure on a nonmagnetic support. The present invention is characterized in that a permalloy film having a diameter of 9'' or more is formed, and a Co--Cr perpendicular magnetization film is formed on the permalloy film.

Due to the magnetic properties required for perpendicular magnetic recording media, it is preferable that the perpendicular coercive force of the perpendicular magnetization film is approximately 4000e or more.In order to satisfy this condition, the f of the permalloy film must be
Δθ5 represents the degree of orientation perpendicular to the film surface of the <111> axis of the cc structure
° must be 9@ or more. Δθ of permalloy film
If 5. is 9° or more, the perpendicular coercive force of the perpendicularly magnetized film of the perpendicular magnetic recording medium can be 4000e or more, which provides useful magnetic properties for the perpendicularly magnetized film of the perpendicular magnetic recording medium.

In contrast, <111> of the rcc structure of permalloy film
Δθ, which represents the degree of orientation of the axis perpendicular to the film surface. If the angle is less than 9°, the perpendicular coercive force of the perpendicularly magnetized film will be approximately 4000 e or less, and the magnetic properties required for a perpendicular magnetic recording medium cannot be satisfied.

Δθ, which represents the degree of orientation perpendicular to the film surface of the <111> axis of the fcc structure of the permalloy film. The degree of orientation of H! is determined when forming a permalloy film on a non-magnetic support. O.

By introducing an impurity gas such as Nt, back pressure can be changed and deterioration can be easily caused. Therefore, by adjusting the amount of impurity gas introduced, Δθ, which represents the degree of orientation perpendicular to the film surface of the <111> axis of the FCC structure of the permalloy film, can be easily
,. The degree of orientation can be adjusted to 9° or more, or to such a degree that the perpendicularly magnetized film has predetermined magnetic properties.

[Effect]

It is generally known that when the degree of orientation perpendicular to the film surface of the first layer deteriorates, the degree of orientation perpendicular to the film surface of the second layer deteriorates even more.

Therefore, if the degree of orientation perpendicular to the film surface of the <111> axis of the fcc structure of the permalloy film, which is the underlying layer of the Go-Cr layer, is degraded, the <ooi> axis of the hcp structure of the Go-Cr layer (C
The degree of orientation perpendicular to the film surface of the film (axis) deteriorates, and the perpendicular coercive force increases.

The reason why the perpendicular coercive force increases due to the deterioration of the degree of orientation perpendicular to the film surface of the C axis of the hcp structure of the Co-Cr layer is that the segregation of the Co-Cr layer increases due to the increased tilt disorder of the crystal axis. As a result, a distribution occurs in the exchange energy within the Co-C layer, which is thought to result in an increase in the pinning energy of the domain wall and the rotational magnetization reversal component.

〔Example〕

Examples of the present invention will be described below with reference to the drawings.
The present invention is not limited to the following examples.

First, the fc of the permalloy film made by covering the high magnetic permeability film.
A preliminary experiment was conducted to examine the degree of deterioration of the degree of orientation of the <111> axis perpendicular to the film surface of the c structure with respect to the manufacturing conditions.

Preliminary experiment example: Using continuous DCC magnetron sputtering equipment, thickness 50p
m, 5 inches wide polyethylene terephthalate (hereinafter P
A permalloy monolayer film was produced using a film (referred to as ET) as a nonmagnetic support.

The conditions for producing the permalloy single layer film are as follows.

Preparation conditions for permalloy single layer film Target = MO permalloy (Ni: 8G, 5% by weight,
Fe: 15% by weight, Mo: 4.5% by weight L 150+ss
x 250 Yorin x 5m5) Sputtering argon pressure:
IX 10-”Torr input power: 1.8k
W (490V x 3.6A) Spunter can roll temperature [: 60℃ Film feed speed: 5 cs/+sin Film thickness: 0.5
μm The back pressure during permalloy film production was reduced to 8.8
We measured Δθ, which is the degree of orientation perpendicular to the film surface of the <111> axis of the fcc structure of the permalloy film when changing r(HlO) and 2Xl(I'↑orr(Ng). Shown in the table.

Table 1 As shown in Table 1, Δθ can be easily degraded by introducing an impurity gas such as N2 or HxO during sputtering to create a permalloy film and increasing the back pressure. By adjusting the amount of the impurity introduced, it is possible to adjust to a predetermined value of Δθ.

Δθ, which represents the degree of orientation perpendicular to the film surface of the <111> axis of the fcc structure of the permalloy film by introducing impurities. Δθ of the permalloy film with respect to the perpendicular coercive force of the Co-01 layer formed on top of it.

An example was conducted regarding the dependence of .

Example 1 Thickness: 50 μm using continuous DC magnetron sputtering equipment
A perpendicular magnetic recording medium consisting of a permalloy film and a Co--Cr layer was prepared using a PET film with a m2 width of 5 inches as a nonmagnetic support.

The conditions for producing the permalloy film and the Co-Cr layer are as follows.

Permalloy film production conditions Target + Mo permalloy (Ni: 8G, 5% by weight,
Fe: 15% by weight, Mo: 4.5-weight X, 150@
IIX 2501111X51111) Sputtering argon pressure: IX 10-'Torr input power: 1
．． 8kW (490Vx3.6A) Sputter can roll temperature: 60℃ Film feed speed: 5 cm/+win film thickness: 0.5
μm Co-Cr layer production conditions Target: Co-Cr (Cr content 121% by weight,
505m x 250mm x 5mm) Sputtering argon pressure: I
:2.0kW (450VX4.5^) Sputter can roll fA degree 7130℃ Film feed speed: l 6.7
cm/sin film thickness: 0.15 μm When manufacturing a perpendicular magnetic recording medium, as shown in Part 2, first a permalloy film (2) is deposited on a non-magnetic support (1).
Δθ3. After forming the Co--Cr layer (3) on top of the Co--Cr layer (3) according to the above-mentioned manufacturing conditions, a sample medium was manufactured.

Example 2 In Example 1, the permalloy film (2
) of Δθ,. is 19.3° (however, this value is 60%6 of the value when only the permalloy film is produced under the same conditions), and then the sample medium was prepared in the same manner as in Example 1. Created.

Example 3 Co as an intermediate layer between the permalloy film and the Co-Cr layer
An application example was performed on a perpendicular magnetic recording medium having a three-layer structure by introducing a -Cr-0 layer.

Thickness: 50μ using continuous DC magnetron sputtering equipment
m9 width 5 inch PET film as a non-magnetic support, permalloy ill, Co-Cr-0 layer, Co-, C
A perpendicular magnetic recording medium consisting of an r layer was manufactured.

The conditions for producing the permalloy film, Co-Cr-0 layer, and Co-Cr layer are as follows.

Permalloy film production condition target: Mo permalloy (Ni: 80.5% by weight
+ Fe: 15 weight ffiχJo: 4.5% by weight,
150as+ X 250ss X 5m+w) Sputtering argon pressure: I
-: 1.8 kW (490 V x 3.6 A) sputter can roll temperature: 60°C Film feed speed: 5 cm/sin Film thickness: 0.5 μm Co-Cr-0 layer production conditions Target: Co-Cr (Cr content: 21 wt. %,,
50+u+ x 250++m x 5mm) Sputter oxygen partial pressure: 4 x 10-'Torr input power
: 1 kll (450VX4.5A) Sputter can roll degree: 130℃ Film feed speed: 20 am/winH accelerated thickness: 17
Co-Cr layer production conditions Target: Co-Cr (Cr content: 121% by weight,
50cm x 250mm x 5m+m) Sputtering argon pressure: I x 10-” Torr input power:
2.0kW (450V x 4.5A) Spunter can roll degree: tao℃ Film feeding speed: 16.7 am/@i (1 film thickness:
In manufacturing a 0.15 μm perpendicular magnetic recording medium, as shown in FIG.
Δθ of the permalloy film (2) by a predetermined back pressure according to the above-mentioned fabrication conditions. After forming the Co-Cr-0 layer (4) with a thickness of about 19°, a Co-Cr-0 layer (4) is formed on top of it.
70 people, with Co-C in the upper layer.
rti! (3) was formed according to the above-mentioned production conditions to produce a sample medium.

Comparative Example 1 Thickness: 50μ using continuous DC magnetron sputtering equipment
A perpendicular magnetic recording medium was fabricated by laminating a Co--Cr underlayer, a permalloy film, and a Co--Cr layer using a PET film having a m1 width of 5 inches as a nonmagnetic support. By introducing a Co-Cr underlayer with an excellent degree of vertical orientation, the Δθ5° of the permalloy film is lowered, and the degree of vertical orientation of the co-Cr layer formed on the upper layer of the permalloy film is made very small, resulting in a perpendicular magnetic field. A recording medium was produced.

The conditions for producing the Co--Cr underlayer, permalloy film, and Co--Cr layer are as follows.

Preparation conditions for Go-Cr underlayer Target: Co-Cr (Cr content: 121% by weight,
50mm x 250mm x 5m+m) Sputtering argon pressure: I
; 2.0kW (450V
．． Preparation conditions for 1 μm permalloy film Target: Mo permalloy (Nis 80.5% by weight,
Fe: Engineering 5 weight Z, no: 4.5 weight ML 150na+
x 250mm x 5mm) Sputtering argon pressure:
IX 10-3Torr input power: 1.8k
W (490Vx3.6A) spanner can roll i degree:
60℃ Film feed speed: 25 am/win Film thickness: 0.1
μm Co-Cr layer production conditions Target: Co-Cr (Cr content 21% by weight,
50m5 x 250mm x 5ms+) Sputtering argon pressure: 'I x 10-' Torr input
7- + 2.0kN (450Vx4.5A) Sputter roll tolerance: 130°C Film feed speed: 5aa/win Film thickness: 0.5μm In manufacturing perpendicular magnetic recording media, first, as shown in Figure 4, A Go-Cr underlayer (
After producing 3a) under the above conditions, a permanent 9i film (
2) Δθ of the permalloy film (2) with a predetermined back pressure.

is 5.3@ (however, this value is lower than that of permalloy film (under the same conditions).
80 when only 2) was made. is the value of ). Next, a Co-Cr layer (
3) was formed according to the above-mentioned production conditions to produce a sample medium.

Comparative Example 2 Using a continuous DC magnetron spanking device, thickness 50I
A perpendicular magnetic recording medium consisting only of a Co--Cr layer was prepared using a 5-inch wide PET film as a nonmagnetic support.

The conditions for producing the Co--Cr layer are as follows.

Co-Cr layer production conditions Target: Co-Cr (Cr content 21% by weight,
50a+m x 250mm
2.0kW (450V A sample medium was produced by sputtering according to the above-mentioned production conditions.

For each of the above sample media, the perpendicular coercive force of the Co--Cr layer was measured by Kerr effect measurement.

The results are shown in Table 2 and Figure 1.

As is clear from Table 2 and FIG.
111>80, which represents the degree of orientation perpendicular to the film surface of the axis. When the angle is less than 9°, the perpendicular coercive force of the Co--Cr layer is not so high as 2500e, but on the other hand, Δθ, which represents the degree of orientation perpendicular to the film surface of the <111> axis of the FCC structure of the permalloy film. is about 9@
Then, the vertical coercive force of Co-Crjil is 4300e, Δ
θ,. is about 190, the perpendicular coercive force of the Co-Cr layer is 6
It exhibited a very high perpendicular coercive force of 700e, and a result was obtained that fully satisfied the magnetic properties as a perpendicular magnetic recording medium.

In addition, in Example 3 using an intermediate layer, the permalloy film and Co-Cr of the two-layer perpendicular magnetic recording medium in Example 2 were
In this case, the perpendicular coercive force of the Co-Cr layer is the first
As indicated by the Δ mark in the figure, it was 9QOOe. That is, it can be seen that when about 200 intermediate layers are introduced, the perpendicular coercive force of the perpendicularly magnetized film increases even more than when no intermediate layer is introduced. therefore,
If necessary, an intermediate layer may be introduced as long as the film thickness is such that the permalloy film does not affect the Co--Cr layer, that is, 200 Å or less.

〔Effect of the invention〕

As is clear from the above explanation, a permalloy film as a high i3 magnetic film is provided below the Co-Cr layer that contributes to recording and reproduction as a perpendicular magnetization film, and the film surface of the <111> axis of the fcc structure of the permalloy film is Δθ, representing the degree of vertical orientation. By deteriorating the Co--Cr layer to nine or more layers, a perpendicularly magnetized film with excellent perpendicular coercive force can be formed even if the Co--Cr layer is manufactured at a low temperature.

Moreover, co-Cr is formed between the permalloy film and the Co-Cr layer.
By interposing the −0 intermediate layer, the perpendicular coercive force of the Co—Cr layer is further increased, and Δθ, which represents the degree of orientation perpendicular to the film surface of the <llll> axis of the fcc structure of the permalloy film. The effect of having nine or more layers is even more exhibited.

Therefore, it is possible to provide a perpendicular magnetic recording medium that has excellent reproduction output and is suitable for achieving high-density magnetic recording.

[Brief explanation of the drawing]

FIG. 1 shows the half-value width Δθ of a rocking curve representing the degree of orientation perpendicular to the film surface of the <111> axis of the fcc structure of the permalloy film. FIG. 3 is a characteristic diagram showing the dependence of the perpendicular coercive force of the Co--Cr layer on the magnetic field. FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a perpendicular magnetic recording medium to which the present invention is applied. FIG. 3 is a schematic cross-sectional view showing an example of the configuration of a perpendicular magnetic recording medium provided with an intermediate layer. FIG. 4 is a schematic cross-sectional view showing an example of the configuration of a perpendicular magnetic recording medium in which a Co--Cr underlayer is provided below a permalloy layer. 1...Non-magnetic support 2...Permalloy film 3...C0-Cr perpendicular magnetization film (Co-Cr layer) Patent applicant Sony Corporation representative Patent attorney Akioka Koboba Sakae Kyashida-

Claims (1)

[Claims] A permalloy film having a rocking curve half-width of 9° or more representing the degree of orientation perpendicular to the film surface of the <111> axis of a face-centered cubic structure is formed on a non-magnetic support, and a Co - A perpendicular magnetic recording medium characterized in that a Cr-based perpendicular magnetization film is formed.