JP2001167423A - Perpendicular magnetic recording medium and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a perpendicular magnetic recording medium having a coercive force and squareness ratio higher than those of the usual perpendicular magnetic recording medium and having a structure to be easily manufactured, and to provide a method for manufacturing the perpendicular magnetic recording medium. SOLUTION: This perpendicular magnetic recording medium has a soft magnetic layer 2, an underlaid layer, a perpendicular magnetic layer 6 and a protecting layer 7 formed in this order on a substrate 1. The underlaid layer has the three-layer structure formed by laminating a Ti-Cr layer 3, a Co-Cr layer 4 and a Ti-Cr layer 5. These layers are continuously formed by a sputtering method by using Ar gas of the same pressure. As a result, the film qualities (film structure) such as the orientation property and crystallinity of the layer 6 are optimized to obtain excellent magnetic characteristics such as larger coercive force and squareness ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a perpendicular magnetic recording medium used for a magnetic disk or the like and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, large-capacity, small-sized magnetic recording devices have been mounted on personal computers and workstations as storage devices. Against this background, magnetic disks are required to have higher recording densities. However, in the case of longitudinal recording type magnetic disks, which are currently widely used in the world, in order to achieve higher densities, the recording bits become finer, and there is a problem of thermal fluctuation of recording magnetization and a high coercive force that cannot be recorded by a recording head. Is required. Therefore, a perpendicular magnetic recording system is being studied as a means for solving these problems and improving the areal recording density. As a method for realizing such a perpendicular magnetic recording medium, a two-layer medium including a soft magnetic layer having a high magnetic permeability and a perpendicular magnetic layer is promising.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a medium having higher coercive force and squareness than conventional perpendicular magnetic recording media. Another object of the present invention is to provide a perpendicular magnetic recording medium having a structure that can be manufactured at a high speed and a method for manufacturing the same.

[0004]

SUMMARY OF THE INVENTION The present inventor has sought to obtain a perpendicular magnetic recording medium having excellent magnetic properties such as a coercive force and a squareness ratio which are larger than those of a conventional perpendicular magnetic recording medium.
As a result of repeated experiments, the following results were obtained. That is, in order to obtain a high coercive force and a large squareness ratio, it is necessary to optimize the film quality (film structure) such as the orientation and crystallinity of the perpendicular magnetic layer. The present invention has been made based on this point of view.

More specifically, in order to achieve the above object, a perpendicular magnetic recording medium according to the first aspect of the present invention is a perpendicular magnetic recording medium having a two-layer structure in which an underlying soft magnetic layer and a perpendicular magnetic layer are formed on a substrate. Wherein a Co-Cr film and a Ti-Cr film are inserted between the soft magnetic underlayer and the perpendicular magnetic layer.

Here, the Co—Cr film and the Ti—Cr film inserted between the soft magnetic underlayer and the perpendicular magnetic layer are provided.
Each of the Cr films is formed to have a thickness of 10 nm to 100 nm and stacked in three layers, and has a structure in which one Co-Cr film is sandwiched between two Ti-Cr films. can do.

The Co-Cr film and the Ti-C film inserted between the underlayer soft magnetic layer and the perpendicular magnetic layer
The composition of the r film is 50-70Co-30-50Cr (at
m%) and 70 to 95 Ti-5 to 30 Cr (atm%).

[0008] The soft magnetic underlayer may be a Ni-Fe film or a Co-Zr-Nb film.

When the underlying soft magnetic layer is a Ni--Fe film, the composition is 70-80 Ni-20-30 Fe (atm
%), And the composition when the underlying soft magnetic layer is a Co—Zr—Nb film is 80 to 90 Co−3 to 5 Zr−8 to 15 N.
b (atm%).

The soft magnetic underlayer has a thickness of 150 nm to 3 nm.
The film can be characterized by being formed to a thickness of 00 nm.

The perpendicular magnetic layer is made of Co—Cr—Pt.
Film or a Co-Cr-Ta-Pt film.

Further, the Co for forming the perpendicular magnetic layer may be made of Co.
-Cr-Pt or Co-Cr-Ta-Pt may be formed to have a thickness of 20 nm to 80 nm.

Further, the perpendicular magnetic layer is formed of the Co—Cr—
The composition of the Pt film is Co-15-25Cr-10-2.
0 Pt, wherein the perpendicular magnetic layer is
The composition of the Cr-Ta-Pt film is Co-15 to 25C.
r-2 to 4 Ta-10 to 20 Pt.

In order to achieve the above object, the invention of a method for manufacturing a perpendicular magnetic recording medium according to claim 10 is directed to the under soft magnetic layer according to any one of claims 1 to 9, The underlayer made of a Co—Cr film and a Ti—Cr film inserted between the perpendicular magnetic layers and the perpendicular magnetic layer are continuously formed at the same film forming pressure.

Here, the underlayer soft magnetic layer, the underlayer consisting of a Co—Cr film and a Ti—Cr film inserted between the underlayer soft magnetic layer and the perpendicular magnetic layer, and the perpendicular magnetic layer, It is characterized by being manufactured by using a sputtering method.

(Operation) In a typical embodiment of the present invention, in a perpendicular magnetic recording medium in which a soft magnetic layer, an underlayer, and a perpendicular magnetic layer are formed in this order, the underlayer is made of Ti-Cr, Co-
Cr, Ti-Cr three-layer structure is formed,
A perpendicular magnetic layer and a protective layer are formed thereon. These layers are formed by sputtering, and the Ar gas pressure at that time is continuously formed at the same pressure. This optimizes the film quality (film structure) such as the orientation and crystallinity of the perpendicular magnetic layer, and provides a perpendicular magnetic recording medium having superior magnetic properties such as a larger coercive force and squareness ratio than conventional perpendicular magnetic recording media. was gotten.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view of a perpendicular magnetic recording medium according to a first embodiment of the present invention. Hereinafter, description will be made based on this drawing.

The perpendicular magnetic recording medium according to the present embodiment has a structure in which Ni--Fe or Co--Zr--Nb
Soft magnetic layer 2 made of Ti-Cr, Co-Cr and T
Bases 3, 4, 5 and Co-Cr-
A perpendicular magnetic layer 6 made of Pt or Co-Cr-Ta-Pt and a protective layer 7 made of C are laminated and formed in this order. Ti for forming the bases 3, 4, and 5
-By the action of the Cr layers 3, 5 or the Co-Cr layer 4,
As will be described later, the perpendicular orientation of the perpendicular magnetic layer 6 is significantly improved as compared with the conventional perpendicular magnetic recording medium.

Next, a method for manufacturing the perpendicular magnetic recording medium according to the present embodiment will be described. The substrate 1 is 3.5 inches (8.8
9 cm). The thickness of the substrate 1 is 1
mm. The size and thickness of the substrate 1 are not essentially related to the present invention. The substrate 1 is plated with Ni-P to form an appropriate texture.

After that, after the substrate 1 is thoroughly cleaned, a film is formed. First, a soft magnetic layer 2 made of Ni—Fe is formed on an Al substrate 1. The target used was 78Ni
-22Fe (atm%) composition. Sputtering is performed with Ar gas using this target, and the film thickness is about 300 nm.
Was formed to a thickness of This film formation is performed at room temperature.
The gas pressure is about 1 Pa.

FIG. 2 shows the result of analyzing the soft magnetic layer 2 formed and formed as described above in this embodiment by a known X-ray diffraction method. From FIG. 2, it can be confirmed that the soft magnetic layer 2 is made of FeNi ₃ crystal.

Subsequently, a Ti—Cr layer 3 as a first underlayer is formed. The target used was 90Ti-10Cr
(Atm%). A using this target
Sputtering was performed with r gas to form a film having a thickness of 50 nm. This film formation is performed at about 250 ° C., and the Ar gas pressure is about 1 Pa.

Further, a Co—Cr layer 4 is used as a second underlayer.
Is formed. The target used was 65Co-35Cr
(Atm%). A using this target
Sputtering was performed with r gas to form a film having a thickness of 30 nm. This film formation is performed at about 250 ° C., and the Ar gas pressure is about 1 Pa.

Next, once again, the third underlayer Ti-
A Cr layer 5 is formed. The target used was 90Ti-1
This is a composition of 0Cr (atm%). Using this target, sputtering was performed with Ar gas to form a film having a thickness of about 20 nm. This film formation is performed at about 250 ° C.
The gas pressure is about 1 Pa.

The reason why the number of the underlayers of the magnetic layer 6 is set to three is that the magnetic layer 6 is appropriately perpendicular to the substrate 1. Without the underlayers 3, 4, and 5, the magnetic layer 6 would grow in the in-plane direction of the substrate 1, and the Co-Cr layer 4
When a magnetic layer is formed directly on the magnetic layer, the magnetic layer is extremely oriented along the c-axis, and the magnetization characteristics deteriorate.

FIG. 3 shows that Co-
The relationship between the Co—Cr film thickness and the coercive force when the magnetic layer 6 is directly formed on the Cr layer is shown. As shown in FIG.
Just by forming o-Cr, the coercive force in the vertical direction (Hc)
It can be seen that is greatly reduced.

The following Table 1 shows that when the soft magnetic layer 2 and the Co-Cr layer are not formed with only the Ti-Cr layer as the underlayer, that is, in the case of a single-layer perpendicular medium, When there is a Ti-Cr layer and a Co-Cr layer,
A comparison of the respective magnetization characteristics when the soft magnetic layer 2 is formed below the Ti—Cr layer is shown.

In Table 1, Al is the substrate 1, Ni-P is the plating layer of the substrate 1, Ni-Fe is the soft magnetic layer 2, Ti-C
r, Co—Cr are the underlayers 3 and 4, and CoCrTaPt is the magnetic layer 6, and the substrate 1 to the magnetic layer 6 are described in the order of lamination from the left.

[0030]

[Table 1]

As shown in Table 1, a perpendicular magnetic recording medium having the largest coercive force can be produced when the soft magnetic layer 2 is provided and the underlying layer is made of Ti-Cr. That is, as shown in
When the o-Cr layer 4 and the magnetic layer 6 are formed successively, the coercive force decreases, and as shown in (3), when the Ti-Cr layer 3 is an underlayer, a high coercive force is easily obtained.

FIG. 4 shows the results of comparison of these perpendicular magnetic recording media having different structures by the X-ray diffraction method. The layer configuration of the perpendicular magnetic recording medium having the characteristic curve of FIG. 4A is the same as the layer configuration of Table 1, and the layer configuration of the perpendicular magnetic recording medium having the characteristic curve of FIG. 4 is the same as that of FIG.
Table 1 shows the layer configuration of the perpendicular magnetic recording medium having the characteristic curve (c).
This is the same as the layer configuration of FIG.

As shown by the characteristic curve of FIG.
The presence of the i-Fe soft magnetic layer 2 increases the coercive force (see Table 1), but deteriorates the crystallinity of the magnetic layer 6. On the other hand, as shown by the characteristic curve in FIG. 4B, it can be seen that the presence of the Co—Cr layer 4 lowers the coercive force (see Table 1), but improves the crystallinity of the magnetic layer 6. As described above, when trying to improve the crystal orientation, magnetic properties such as coercive force are sacrificed,
When the soft magnetic layer 2 is formed to increase the coercive force, the crystallinity deteriorates.

Therefore, the present inventor studied a layer configuration for increasing the coercive force as much as possible and forming a magnetic layer having good crystallinity to some extent to improve the characteristics as a magnetic recording medium. As shown in FIG.
-Cr-50nm / Co-Cr-30nm / Ti-Cr
By forming a three-layer structure of −20 nm, as shown in FIG. 4, a film having good crystallinity when the Co—Cr layer 4 is used is formed on the Ti—Cr layer 3 to provide a high coercive force. It has been found that a medium can be formed.

As described above, the underlayer laminated between the soft magnetic layer 2 and the magnetic layer 6 is composed of the Ti—Cr layer 3, the Co—Cr layer 4,
Assuming a three-layer structure of the Ti—Cr layer 5, the magnetic layer 6 is made of Co—
Since the magnetic layer is formed on the Ti—Cr layer 3 under the influence of the crystal structure of the Cr layer 4, a magnetic layer having a certain degree of crystallinity can be formed without lowering the coercive force.

For such a reason, the perpendicular magnetic layer 6 is formed on the underlayer 3.4.5 formed as shown in FIG. The perpendicular magnetic layer 6 is made of Co—Cr—Pt or Co—Cr—T
a-Pt is used.

In this embodiment, as an example, a case where Co—Cr—Ta—Pt is used for the perpendicular magnetic layer 6 will be described.
The target used for forming the perpendicular magnetic layer 6 is Co.
The composition is -16Cr-2Ta-12Pt (atm%). Using this target, sputtering was performed with Ar gas to form a perpendicular magnetic layer 6 with a thickness of about 50 nm.
This film formation is performed at about 250 ° C., and the Ar gas pressure is about 1
Pa.

Finally, a C film is formed as a protective layer 7 on the surface. The target used for this was C. Sputtering is performed with Ar gas using this target, and a film thickness of about 5 n
m was formed. The film is formed at about 250 ° C.
The Ar gas pressure is about 1 Pa.

The perpendicular magnetic recording medium on which film formation has been completed in this way is cooled and taken out of the manufacturing apparatus.

FIGS. 5A and 5B show the longitudinal direction (FIG. 5A) and the perpendicular direction (FIG. 5A) of the perpendicular magnetic recording medium obtained by the above-described manufacturing method. (B))
Shows the evaluated magnetic properties. As can be seen from FIG. 5A, there is almost no coercive force in the longitudinal direction of the perpendicular magnetic recording medium, and it can be confirmed that the medium is a perpendicular medium. FIG.
As a result of the evaluation of the magnetic properties in the perpendicular direction of (b), a perpendicular magnetic recording medium having a coercive force of about 3400 Oe and a squareness ratio of about 0.7 was obtained.

(Second Embodiment) Next, as a second embodiment of the present invention, in the layer structure shown in FIG. 1, CoZrNb is used for the soft magnetic layer 2 and Co-Cr-
The case of a perpendicular magnetic recording medium using Pt will be described.

The substrate 1 is an Al substrate having a size of 3.5 inches (8.89 cm). The thickness of the substrate 1 is 1 mm. The size and thickness of the substrate 1 are not essentially related to the present invention. The substrate 1 is plated with Ni-P to form an appropriate texture.

After that, the substrate 1 is thoroughly cleaned, and then a film is formed. First, a soft magnetic layer 2 made of Co—Zr—Nb is formed on an Al substrate 1. Therefore, the target used had a composition of 87Co-5Zr-8Nb (atm%). Using this target, sputtering was performed with Ar gas to form a soft magnetic layer 2 with a thickness of about 300 nm.
This film formation is performed at room temperature, and the Ar gas pressure is about 1 Pa.

Subsequently, a Ti—Cr layer 3 as a first underlayer is formed. The target used for this was 90Ti-
This is a composition of 10Cr (atm%). Using this target, sputtering was performed with Ar gas to form a Ti—Cr layer 3 with a thickness of about 50 nm. This film is about 250 ° C
The Ar gas pressure is about 1 Pa.

Further, a Co—Cr layer 4 is formed as a second underlayer. Therefore, the target used was 65Co-
The composition is 35Cr (atm%). Using this target, sputtering was performed with Ar gas to form a Co—Cr layer 4 having a thickness of about 30 nm. This film is about 250 ° C
The Ar gas pressure is about 1 Pa.

Next, once again, the third underlayer Ti
-Cr layer 5 is formed. The target used for this was 9
The composition is 0Ti-10Cr (atm%). Sputtering is performed with Ar gas using this target, and a film thickness of about 20
A Ti—Cr layer 5 was formed to a thickness of nm. This film formation is performed at about 250 ° C., and the Ar gas pressure is about 1 Pa.

The perpendicular magnetic layer 6 was made of Co-Cr-Pt. The target used for this was Co-20Cr-10
It is a composition of Pt (atm%). Using this target, sputtering was performed with Ar gas to form a perpendicular magnetic layer 6 with a thickness of about 50 nm. This film formation is performed at about 250 ° C., and the Ar gas pressure is about 1 Pa.

Finally, a C film is formed as a protective layer 7 on the surface. The target used for this was C. Sputtering is performed with Ar gas using this target, and a film thickness of about 5 n
The protective layer 7 was formed to a thickness of m. This film is about 250 ° C
The Ar gas pressure is about 1 Pa.

The perpendicular magnetic recording medium on which film formation has been completed in this way is cooled and taken out of the manufacturing apparatus.

FIG. 6 shows data for evaluating the perpendicular magnetic characteristics of the perpendicular magnetic recording medium of the present embodiment obtained by such a manufacturing method. Squareness ratio 0.7 with holding force of about 3000
A perpendicular magnetic recording medium of a degree was obtained.

As in this embodiment, the soft magnetic layer 2 is made of Co-
Even if the magnetic layer 6 is made of Zr-Nb and Co-Cr-Pt is used, a perpendicular magnetic recording medium comparable to that of the first embodiment can be obtained.

[0052]

As described above, according to the present invention,
In a perpendicular magnetic recording medium having a laminated structure of a soft magnetic layer, an underlayer, a magnetic layer, and a protective layer on a substrate, an appropriate soft magnetic layer is used, and the underlayer is made of, for example, two Ti—Cr layers and one Co layer. -By forming a three-layer structure sandwiching Cr, the perpendicular magnetic layer can have an appropriate orientation and crystallinity, and obtain a perpendicular magnetic recording medium having high coercive force and squareness ratio. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a laminated section of a perpendicular magnetic recording medium according to first and second embodiments of the present invention.

FIG. 2 shows a Ni-F formed according to the first embodiment of the present invention.
FIG. 14 is a characteristic diagram showing an X-ray diffraction analysis result of the e soft magnetic layer.

FIG. 3 is a characteristic diagram showing a relationship between a film thickness of a Co—Cr layer constituting a perpendicular magnetic recording medium and a coercive force.

FIG. 4 is a characteristic diagram showing an X-ray diffraction analysis result of a perpendicular magnetic recording medium having different layer configurations.

FIG. 5 (a) is a longitudinal magnetic characteristic of a perpendicular magnetic recording medium manufactured by the manufacturing method according to the first embodiment of the present invention;
FIG. 4B is a characteristic diagram showing the perpendicular magnetic characteristics of the perpendicular magnetic recording medium.

FIG. 6 is a characteristic diagram showing perpendicular magnetic properties of a perpendicular recording medium manufactured by a manufacturing method according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 soft magnetic layer 3 Ti-Cr layer 4 Co-Cr layer 5 Ti-Cr layer 6 magnetic layer (perpendicular magnetic layer) 7 protective layer

Claims (11)

[Claims] 1. A perpendicular magnetic recording medium having a two-layer structure in which an underlying soft magnetic layer and a perpendicular magnetic layer are formed on a substrate, wherein a Co—Cr film and a Ti— A perpendicular magnetic recording medium having a Cr film inserted therein. 2. The Co—Cr film and the Ti—Cr film interposed between the underlying soft magnetic layer and the perpendicular magnetic layer are each formed to a thickness of 10 nm to 100 nm to form three layers. Laminated, one Co-Cr film is
2. The perpendicular magnetic recording medium according to claim 1, wherein the perpendicular magnetic recording medium has a structure sandwiched between i-Cr films. 3. The composition of the Co—Cr film and the Ti—Cr film inserted between the underlying soft magnetic layer and the perpendicular magnetic layer is 50 to 70 Co-30 to 50 Cr (atm).
%), And 70 to 95 Ti-5 to 30 Cr (atm%). 4. The perpendicular magnetic recording medium according to claim 1, wherein the soft magnetic underlayer is a Ni—Fe film or a Co—Zr—Nb film. 5. The composition when the soft magnetic underlayer is a Ni—Fe film is 70 to 80 Ni-20 to 30 Fe (atm%).
When the soft magnetic underlayer is a Co-Zr-Nb film, the composition is 80-90Co-3-5Zr-8-15Nb.
The perpendicular magnetic recording medium according to claim 4, wherein the ratio is (atm%). 6. The underlayer soft magnetic layer has a thickness of 150 nm to 300 nm.
The perpendicular magnetic recording medium according to any one of claims 1 to 5, wherein the perpendicular magnetic recording medium is formed to a thickness of nm. 7. The perpendicular magnetic recording medium according to claim 1, wherein the perpendicular magnetic layer is a Co—Cr—Pt film or a Co—Cr—Ta—Pt film. 8. The Co—C forming the perpendicular magnetic layer
The film thickness of r-Pt or Co-Cr-Ta-Pt is 2
The perpendicular magnetic recording medium according to claim 7, wherein the perpendicular magnetic recording medium is formed to a thickness of 0 nm to 80 nm. 9. The method according to claim 1, wherein the perpendicular magnetic layer is formed of the Co—Cr—Pt.
The composition of the film is Co-15-25Cr-10-20P.
t, wherein the perpendicular magnetic layer is formed of the Co—Cr
The composition of the Ta-Pt film is Co-15 to 25Cr-
9. The perpendicular magnetic recording medium according to claim 7, wherein the composition has a composition of 2 to 4 Ta-10 to 20 Pt. 10. The lower soft magnetic layer according to claim 1, comprising a Co—Cr film and a Ti—Cr film inserted between the soft underlayer and the perpendicular magnetic layer. A method for manufacturing a perpendicular magnetic recording medium, wherein the underlayer and the perpendicular magnetic layer are continuously formed at the same film forming pressure. 11. The underlayer soft magnetic layer, a Co—Cr film interposed between the underlayer soft magnetic layer and the perpendicular magnetic layer, and T
The method of manufacturing a perpendicular magnetic recording medium according to claim 10, wherein the underlayer made of an i-Cr film and the perpendicular magnetic layer are produced by a sputtering method.