JP2002342919A - Perpendicular magnetic recording medium and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process design suitable for mass production without requiring heat treatment after deposition for the purpose of obtaining a sufficient exchange bond of an antiferromagnetic film and a soft magnetic lining layer in manufacturing of a perpendicular magnetic recording medium. SOLUTION: A nonmagnetic substrate is heated to a temperature of 150 to 400 deg.C within the same deposition device prior to deposition of at least the antiferromagnetic film and thereafter the antiferromagnetic layer and the soft magnetic layer are continuously deposited while a magnetic field is impressed thereto, by which the large exchange bond is obtained and the domain wall formation of the soft magnetic lining layer is suppressed without subjecting these layers to the heat treatment after the deposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a perpendicular magnetic recording medium mounted on various magnetic recording devices and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a technique for realizing a higher density of magnetic recording, a perpendicular magnetic recording method is attracting attention instead of a conventional longitudinal magnetic recording method.

A perpendicular magnetic recording medium has a magnetic recording layer of a hard magnetic material and a backing layer formed of a soft magnetic material used for recording on the recording layer and having a role of concentrating a magnetic flux generated by a magnetic head. Included in components. It is known that spike noise, which is one of the problems in the perpendicular magnetic recording medium having such a structure, is caused by domain walls formed in a soft magnetic film serving as a backing layer. Therefore, in order to realize the perpendicular magnetic recording method, it is necessary to prevent the formation of the domain wall of the soft magnetic underlayer.

The control of the domain wall of the soft magnetic underlayer is described in, for example, JP-A-6-180834 and JP-A-10-180834.
As described in JP-A-214719, a method of forming a ferromagnetic layer of a Co alloy or the like on an upper layer or a lower layer of a soft magnetic underlayer and magnetizing the same in a desired direction,
A method has been proposed in which an antiferromagnetic thin film is formed and magnetization is pinned using exchange coupling.

[0005]

A method of controlling a domain wall by exchange coupling with a soft magnetic underlayer using an antiferromagnetic film is described below. Can be very effective. However, in order to obtain sufficient exchange coupling, for example, as described in the above-mentioned Japanese Patent Application Laid-Open No. Hei 10-214719, a heat treatment after film formation is necessary, which is very disadvantageous in mass production. Was.

[0006]

Means for Solving the Problems The present inventors have studied diligently to effectively control the domain wall of the soft magnetic underlayer using an antiferromagnetic film and to design a process suitable for mass production. As a result, before the antiferromagnetic film is formed, the nonmagnetic substrate is heated to 150 ° C. or more and 400 ° C. or less in the same film forming apparatus, and then the magnetic domain control layer and the soft magnetic layer are continuously applied while applying a magnetic field. It has been found that by forming a film, a large exchange coupling can be obtained without performing a heat treatment or the like after the film is formed, and formation of a magnetic domain wall of the soft magnetic underlayer can be suppressed.

That is, a first aspect of the present invention is to provide at least an underlayer, an orientation control layer, a magnetic domain control layer using an antiferromagnetic material containing Mn, a backing layer using a soft magnetic material on a nonmagnetic substrate, A method for manufacturing a perpendicular magnetic recording medium, in which an intermediate layer, a magnetic recording layer, a protective layer, and a liquid lubricant layer are sequentially stacked, wherein at least the magnetic domain control layer is formed in the same film forming apparatus before forming the magnetic domain control layer. After heating the non-magnetic substrate, the magnetic domain control layer and the soft magnetic layer are continuously formed while applying a magnetic field.

According to a second aspect of the present invention, in the above-mentioned manufacturing method, the non-magnetic substrate is heated at a temperature of 150 ° C. or more and 400 ° C. or less.

According to a third aspect of the present invention, there is provided a perpendicular magnetic recording medium manufactured by the above manufacturing method, wherein the soft magnetic underlayer has a single magnetic domain.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is a schematic sectional view of a perpendicular magnetic recording medium showing one embodiment of the present invention. It has a structure in which at least an underlayer 2, an orientation control layer 3, an antiferromagnetic layer 4, a soft magnetic layer 5, an intermediate layer 6, a magnetic recording layer 7, and a protective layer 8 are sequentially formed on a nonmagnetic substrate 1. Further, an embodiment is shown in which a liquid lubricant layer 9 is further formed thereon.

As the liquid lubricant layer 9, a conventionally used material can be used. For example, a perfluoropolyether-based lubricant can be used.
The conditions such as the film thickness of the liquid lubricant layer 9 can be the same as those used for a normal magnetic recording medium.

As the protective layer 8, a conventionally used protective film can be used. For example, a protective film mainly composed of carbon can be used. The conditions such as the film thickness of the protective layer 8 can be the same as those used for a normal magnetic recording medium.

The magnetic recording layer 7 includes, but is not limited to, a CoCr-based alloy crystalline film, a rare earth-transition metal alloy amorphous film, a Co-based multilayer film, or a laminated film thereof. CoCr-based alloy crystalline films include CoCr, CoCrTa, CoCrPt,
CoCrPtX (X = B, Ta, Zr, Nb), etc., the rare earth-transition metal alloy amorphous film contains TbCo, TbFeCo, TbCoCr, etc., and the Co-based multilayer film includes [Co / Pd] _n and [Co / Pt] _n , but is not limited thereto. The thickness is not particularly limited, but is preferably 10 nm or more and 50 nm or less in order to obtain good characteristics as a perpendicular magnetic recording medium.

The intermediate layer 6 preferably controls the crystal grain size of the magnetic layer, controls the initial growth layer of the magnetic layer, and controls the crystal grain size of the magnetic layer in order to vertically orient the c-axis of the crystal grain of the magnetic layer. Used to promote segregation and the like. It is also used to break the magnetic coupling between the soft magnetic backing layer and the magnetic recording layer. The thinner the layer, the more advantageous for high density recording. Materials include Ta, Ti, TiCr, CoCr, Co
CrX (X = B, V, Mn, Nb, Mo, Ru Ta, W), Ru, Pd, Pt
And the like, but is not limited thereto.

The soft magnetic backing layer 5 is necessary for concentrating the magnetic flux emitted from the single-pole head on the magnetic recording layer, and functions as a part of the head. It is advantageous that the thickness of the layer is large. However, from the viewpoint of productivity, it is advantageous to be as thin as possible. The optimum value of the film thickness varies depending on the structure and characteristics of the magnetic head used for recording. However, it is desirable that the film thickness be 50 nm or more and 300 nm or less in consideration of productivity. Materials include NiFe, FeAlSi, CoZrNb, CoTaZr, FeTaC, CoNiFe, F
There are eN-based alloys and the like, but not limited to these.

[0016] Only by forming the soft magnetic underlayer, many magnetic domains are formed in an attempt to reduce magnetic energy. At this time, a leakage magnetic flux is generated from a magnetization moment that forms a domain wall generated between magnetic domains, and a magnetic flux generated in a vertical direction is observed as spike noise when measuring electromagnetic conversion characteristics.

The magnetic domain control layer 4 is an antiferromagnetic layer provided below the soft magnetic underlayer to suppress the formation of the magnetic domain wall. This is to prevent the formation of magnetic domains in the soft magnetic underlayer by utilizing exchange coupling acting between the diamagnetic layer and the soft magnetic underlayer. Thereby, the magnetization of the soft magnetic underlayer is aligned in one direction (in this case, the radial direction of the perpendicular magnetic recording medium), and no spike noise is observed. When the exchange coupling magnetic field is small, the magnetization is directed in the direction only by applying a slight external magnetic field, and a magnetic domain is formed to generate spike noise. However, when the exchange coupling magnetic field is increased, the resistance to the external magnetic field is increased, and no spike noise is generated.

In this case, an exchange coupling magnetic field can be obtained without heating the substrate, but a larger exchange coupling magnetic field can be obtained because the crystal orientation of the antiferromagnetic layer is improved by forming the film by heating. . By performing heating film formation,
This is because the exchange coupling magnetic field as unidirectional anisotropy increases because the dispersion of the magnetization decreases.

The magnetic domain control layer 4 is preferably made of a Mn-based alloy in view of the magnitude of the obtained exchange coupling magnetic field and the ease of manufacture. FeMn, NiMn, CoMn, IrMn, PtMn
However, the present invention is not limited to this. Although the film thickness is not particularly limited, it is preferably about 5 nm or more and about 50 nm in order to obtain an appropriate exchange coupling and be suitable for mass production.

The orientation control layer 3 is a layer necessary for improving the crystal orientation of the antiferromagnetic layer which is a magnetic domain control layer. When there is no orientation control layer, even if an antiferromagnetic layer is present, an exchange coupling magnetic field cannot be obtained because the crystal orientation of the antiferromagnetic layer is poor. By using a single metal or alloy-based material having a face-centered cubic structure, the orientation of the antiferromagnetic layer is improved. Examples of the material system include, but are not limited to, Cu, Ir, Pd, Pt, alloys thereof, and NiFe alloys. The film thickness is not particularly limited, but is preferably 50 nm or less in order to be suitable for mass production.

The underlayer 2 is a layer used to control the fine structure of the orientation control layer. The use of the underlayer smoothes the surface of the substrate, thereby controlling the initial layer control of the orientation control layer and the orientation. Performs control and the like. As a material system, T
a, Ti, Zr, Nb and alloys thereof. The thickness is not particularly limited, but is preferably 3 nm or more and 50 nm or less in order to be suitable for mass production.

It is sufficient that at least one of the orientation control layer and the underlayer exists between the non-magnetic substrate and the antiferromagnetic layer. A coupling magnetic field was obtained.

As the non-magnetic substrate, there can be used a NiP-plated Al alloy, tempered glass, crystallized glass or the like, which is used for ordinary magnetic recording media.

In manufacturing the perpendicular magnetic recording medium of the present invention, at least before forming the antiferromagnetic layer, the nonmagnetic substrate is heated using a heater or the like in the same film forming apparatus, and then continuously. It is necessary to form the antiferromagnetic layer and the soft magnetic layer while applying a magnetic field in the radial direction of the nonmagnetic substrate.
The type of heater used for heating is not limited as long as the temperature of the non-magnetic substrate rises. However, from the viewpoint of productivity, it is desirable to use a lamp heater because temperature control is simple and easy.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

(Example 1) A chemically strengthened glass substrate (for example, N-5 glass substrate manufactured by HOYA) having a smooth surface was used as a non-magnetic substrate, and after washing, introduced into a sputtering apparatus, and a Ta target was used. A Ta underlayer is formed to a thickness of 5 nm, and then a NiFe-based alloy
An alloy thin film was formed to a thickness of 5 nm. Subsequently, heating is performed using a lamp heater so that the substrate temperature becomes 250 ° C., an antiferromagnetic film is formed to a thickness of 5 nm using an IrMn alloy target, and then softened using a CoZrNb alloy target. A magnetic film was formed to a thickness of 100 nm. At the time of forming these antiferromagnetic layers and soft magnetic layers, 50O
The magnetic field of e was applied.

Subsequently, heating was performed using a lamp heater so that the substrate surface temperature was again 250 ° C.
10 nm for the intermediate film and 30 n for the CoCrPt magnetic recording layer.
m, and finally a carbon protective film was formed to a thickness of 10 nm and then taken out of the vacuum apparatus. All of these films were formed by DC magnetron sputtering under an Ar gas pressure of 5 mTorr. Thereafter, a liquid lubricant layer of 2 nm made of perfluoropolyether was formed by dipping to obtain a perpendicular magnetic recording medium.

(Comparative Example 1) As a comparative example for confirming an output waveform in the case where no spike noise occurs, in the method for manufacturing a perpendicular medium shown in Example 1, a non-magnetic substrate was introduced into a sputtering apparatus after cleaning. Then, without performing each film forming process from the base film to the soft magnetic film, heating was performed to 250 ° C. using a lamp heater, and then the Ti film was
Next, a CoCrPt magnetic recording layer was formed to a thickness of 30 nm, and finally a carbon protective film was formed to a thickness of 10 nm and then taken out of the vacuum apparatus. Thereafter, a liquid lubricant layer of 2 nm made of perfluoropolyether was formed by dipping to obtain a perpendicular magnetic recording medium.

In the method for manufacturing a perpendicular magnetic recording medium shown in Example 1, the magnetization curve in the substrate radial direction of a sample taken out of a sputtering apparatus without forming an intermediate layer, a magnetic recording layer, a protective layer and a liquid lubricant layer was determined. Measured with a vibrating sample magnetometer,
The exchange coupling magnetic field was measured. In order to confirm the presence or absence of a magnetic domain wall formed on the soft magnetic underlayer of the completed perpendicular magnetic recording medium, the ratio of the fluctuation to the average value of the output waveform in the state where no signal is written was measured using a spin stand tester. (COV) was measured to check for the presence of spike noise.

FIG. 2 shows the magnitude of the exchange coupling magnetic field with respect to the substrate heating temperature. Even in a medium formed at room temperature without heating the substrate, an exchange coupling magnetic field of about 7 Oe is obtained by using an underlayer and an orientation control layer below the antiferromagnetic layer. The value of the exchange coupling magnetic field increases as the substrate heating temperature increases, shows a maximum value of about 23 Oe at 250 ° C. heating, and then gradually decreases to 8 ° C. at 450 ° C. heating.
It will be reduced to a value of about Oe.

Table 1 shows the COV value as an index indicating the presence of spike noise with respect to the heating temperature. The table also shows the value of the exchange coupling magnetic field at each heating temperature. Further, as a comparative example for confirming the presence or absence of spike noise, the result of the perpendicular magnetic recording medium having the layer configuration shown in Comparative Example 1 is also shown in the same table. In the case of the medium configuration shown in Comparative Example 1 having no soft magnetic backing layer, the value of COV is 5%. In the medium formed at room temperature without heating the substrate, the COV value shows 12% despite the fact that an exchange coupling magnetic field of about 7 Oe is obtained, and the spike noise cannot be completely suppressed at 7 Oe. I understand. In contrast,
In a medium having an exchange coupling magnetic field of 10 Oe or more, the COV value is 5%, which is the same as when no spike noise is generated.
Generation of spike noise is completely suppressed. Therefore, 1 is necessary to completely suppress spike noise.
It can be seen that in order to obtain an exchange coupling magnetic field of 0 Oe or more, the substrate heating temperature needs to be 150 ° C. or more and 400 ° C. or less.

[0032]

[Table 1]

[0033]

As described above, according to the present invention, the non-magnetic substrate is heated to 150 ° C. or more and 400 ° C. or less in the same film forming apparatus at least before the anti-ferromagnetic film is formed. By forming the antiferromagnetic layer and the soft magnetic layer while applying a magnetic field, a large exchange coupling can be obtained without performing a heat treatment or the like after the film formation, and the suppression of domain wall formation of the soft magnetic backing layer can be achieved. You can do it. According to this manufacturing method, the existing film forming apparatus can be used as it is, and the required uniform and high exchange coupling can be obtained by a very simple manufacturing method of performing heating using a heater. It is also very suitable for mass production.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a perpendicular magnetic recording medium showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating a change in a value of an exchange coupling magnetic field with respect to a substrate heating temperature for explaining an example of the present invention.

[Explanation of symbols]

 1: Non-magnetic substrate 2: Underlayer 3: Orientation control layer 4: Antiferromagnetic layer 5: Soft magnetic backing layer 6: Intermediate layer 7: Magnetic recording layer 8: Protective layer 9: Liquid lubricating layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D006 CA01 CA03 CA05 DA08 EA03 EA05 5D112 AA03 AA04 FA04 FB29

Claims (3)

[Claims] 1. A magnetic domain control layer using an antiferromagnetic material containing at least an underlayer, an orientation control layer, and Mn on a nonmagnetic substrate.
A method for manufacturing a perpendicular magnetic recording medium in which a backing layer using a soft magnetic material, an intermediate layer, a magnetic recording layer, a protective layer, and a liquid lubricant layer are sequentially stacked, at least before forming the magnetic domain control layer. And heating the non-magnetic substrate in the same film forming apparatus, and subsequently forming a magnetic domain control layer and a soft magnetic layer while applying a magnetic field. 2. The method according to claim 1, wherein the non-magnetic substrate is heated at 150 ° C. to 400 ° C.
The method for manufacturing a perpendicular magnetic recording medium according to claim 1, wherein the heating is performed in the following manner. 3. The perpendicular magnetic recording medium manufactured by the manufacturing method according to claim 1, wherein the soft magnetic underlayer has a single magnetic domain.