JPS63247911A - Two-layered film medium for perpendicular magnetic recording - Google Patents

Abstract

PURPOSE:To obtain excellent recording and reproducing characteristics and corrosion resistance by using a ferromagnetic metal and polymer-contg. amorphous soft magnetic film as high magnetic permeability films. CONSTITUTION:A two-layered film medium is obtd. by forming the polymer- contg. amorphous soft magnetic film on a nonmagnetic substrate and further, laminating a perpendicular magnetic anisotropy film thereon. The polymers are distributed at intervals of the extremely proximate distances and exist entirely integrally in the ferromagnetic metal of this amorphous soft magnetic film and, therefore, the crystallization of the ferromagnetic metal is hindered and said metal is converted to the amorphous metal. The polymers to be used for formation of such soft magnetic film have the number of carbon atoms. preferably in a 10-1,000 range. Disturbance in the orientability of the recording magnetic layer to be provided on the high magnetic permeability layer is thereby obviated and, therefore, the two-layered film medium for perpendicular magnetic recording having the excellent recording and reproducing characteristics and corrosion resistance is obtd.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a double-layer film medium for perpendicular magnetic recording.

More specifically, the present invention relates to a two-layer film medium for perpendicular magnetic recording having an amorphous soft magnetic film.

[Prior Art] In principle, there is a perpendicular magnetic recording method as a magnetic recording method suitable for l, -5 density recording. In this method, a magnetic thin film having superimposed magnetic anisotropy is used as the magnetic layer, and the direction of magnetization is directed perpendicular to the surface of the recording medium. In this way, during high-density recording, the demagnetizing field inside the medium is reduced, resulting in an excellent +IT raw output.

Permalloy (NiFe) film is known as a high magnetic permeability material for such double-layer media for perpendicular magnetic recording (
Special Publication No. 58-91).

When a permalloy-based material is used as a high magnetic permeability material, the (111) plane of the fee structure of permalloy preferentially grows parallel to the film surface, but the degree of orientation is not good. In addition, permalloy's ct 11) The shortest distance between the original r is 2.50 people, and C
The shortest distance i between the original r in the (001) plane of oCr! i12.5
Very close to the two. Therefore, it is possible to directly apply C to the permalloy film.
When oCr is formed, the degree of orientation of the C-axis of the CoCr film also deteriorates because the degree of orientation of the Permalloy film, which is the base layer, is not good.
The magnetic properties of the 0Cr film itself deteriorate.

Moreover, discs using a soft magnetic overlayer made of permalloy or the like cannot be used in places where the temperature and humidity are high, where the air contains salt, or where corrosive gases such as sulfuric acid gas are present. There is a problem in that the base film is eroded from the edge portion of the outer periphery, the magnetic permeability gradually decreases, and the output decreases.

[Problems to be Solved by the Invention] This invention solves the deterioration of magnetic properties and corrosion resistance caused by disordered crystal orientation as described in item 11 above, and improves magnetic permeability with excellent recording and reproducing properties and corrosion resistance. 1-1 objective is to provide a base film.

[Means for Solving the Problems] As a result of extensive experiments and research carried out by the present inventors over many years, the cocr ferromagnetic metal and the polymer were deposited at a predetermined deposition rate ratio from separate crucibles or hearths. It was discovered that when a ferromagnetic metal film having a structure containing the metal or the ``1'-metal and a polymer is prepared by simultaneous RT dry evaporation, this ferromagnetic metal film becomes an amorphous soft magnetic film. It was done. The present invention was completed based on this knowledge.

A two-layer film medium can be obtained by forming this polymer-containing amorphous soft magnetic film as a high magnetic permeability layer on the non-magnetic substrate -1-, and further laminating a superimposed magnetic anisotropic film on this 1-. .

Although the exact mechanism has not yet been elucidated and remains a matter of speculation, in the amorphous soft magnetic film of the present invention, the polymers are distributed in the ferromagnetic metal at very close distances, creating a harmonious and integrated structure. It is thought that the presence of ferromagnetic metal inhibits the crystallization of the ferromagnetic metal and causes it to become amorphous.

In the case of columnar metal particles, the outer surface of the particle may be coated with polymer, but it is assumed that the polymer is relatively uniformly distributed within the metal at very close intervals. . In the case of granular soft metals, the relationship seems to be similar to that of the human body.

In this specification, the term "amorphous" is used to refer to completely amorphous soft magnetic films as well as soft magnetic films containing some crystalline parts in the amorphous state. This is to include a soft magnetic film, which is a collection of microcrystals that cannot be detected by X-ray diffraction.

In fact, no one skilled in the art could have imagined that a polymer would cause a ferromagnetic metal to become amorphous until the present invention was completed. Even if a ferromagnetic metal is vapor-deposited alone without using a polymer, the ferromagnetic metal rarely becomes amorphous.

As described above, according to the method of the present invention, a high magnetic permeability soft magnetic film can be formed on a non-magnetic substrate by simply dry-evaporating a ferromagnetic metal and a polymer at a predetermined deposition rate ratio for 1"C at the same time. 10
Since it can be laminated with a probability of close to 0%, productivity is extremely high.

Furthermore, since the soft magnetic film is amorphous, if the magnetic film laminated on top of it is crystalline, its crystal content is determined, and if it is amorphous, its amorphousness is determined. No disturbance.

From the viewpoint of productivity, the method used to fabricate this amorphous soft magnetic film as a high magnetic permeability film is simultaneous vapor deposition of a ferromagnetic metal and a polymer. Although it is considered to be good, simultaneous sputtering method of ferromagnetic metal and polymer 1 using ferromagnetic metal as a target and sputtering ferromagnetic metal using a mixed gas of Ar and 7-mer or only 7-mer. ．． You can also use the method of Alternatively, a ferromagnetic metal may be vacuum-deposited at the same time as plasma polymerization using monomer gas is performed. Historically, simultaneous ion brating methods for ferromagnetic metals and monomers can also be performed.

As the ferromagnetic metal, NFesCOINi, an alloy thereof, or an alloy between Fe%C01Ni and other elements can be used.

Nitrides or oxides of these can be used as well.

Such magnetic materials are well known to those skilled in the art. According to the method of the present invention, metals that have conventionally been widely used as magnetic materials can be made amorphous, whether in the form of a single alloy or a compound.

The soft magnetic underlayer used in the present invention includes 1.
Although an amorphous soft magnetic overlayer film as described above is preferable, it is not necessarily an amorphous film, and any soft magnetic material having a coercive force of 200e or less may be used.

The polymer that can be used to form the soft magnetic film of the present invention is a linear or network polymer having a carbon atom number in the range of 10 to 1000, preferably 30 to 500, more preferably 70 to 200. r:'L-isomer, for example, polyethylene, polypropylene, polystyrene, polybutadiene,
In addition to polymers such as polycarbonate, polyamide, polyide, polyvinyl chloride, polyvinyl acetate, and polyurethane, fluorocarbon-based polymers such as polytetrafluoroethylene, and silicon-based polymers based on Si may be used.

The mixing ratio of the ferromagnetic metal and the polymer is generally such that the polymer is 5v01% or more (3Qvo1% or less, preferably 12
VO 1% or more, and 40 VO 1% or less. If the polymer content is less than 5 vol %, the desired high permeability amorphous soft magnetic film will not be formed. On the other hand, if it is (3Qvo1% or more), the separation of the ferromagnetic metal particles by the polymer becomes large, and the magnetic properties gradually become hard, which is not preferable.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following examples.

Using a batch method 1' [empty evaporation apparatus] as shown in Fig. 1, a CoCr film was formed on a high magnetic permeability film and a high magnetic permeability film-1- under the following conditions. Then, a two-layer membrane medium was prepared.

Preparation conditions (1) Substrate: Polyimide film (film thickness 40 μm) (2
) Substrate temperature = 150°C (3) Ferromagnetic metal: CoCr (1"[,"!The ingot used for vapor deposition has a Cr concentration of 16 vt%) (4) Polymer: Polyethylene (average molecular 1a: 1000) (5 ) 3'j, emptyness: ultimate vacuum 4X 10-'
When producing a CoCr-polyethylene film, which is a Torr high magnetic permeability film, 2X 10-S TorrCoCr
2X l O-6 Torr when producing a vertical magnetic anisotropic film (6) Evaporation rate: CoCr 15 people/see (same when producing a high magnetic permeability film and a vertical magnetic anisotropic film): Polyethylene 4 .5 people/5ee CoCr was vacuum-deposited using an electric gun heating method, and polyethylene was vacuum-deposited using a resistance heating method.

Only a CoCr-polyethylene vapor-deposited film (CoCr-PE film) was fabricated with a film thickness of 8,000 yen. For comparison, CoCr
A single film was also produced under the same conditions. (However, the degree of vacuum is 1~
It was set at 2x 10-' Torr. ) In order to investigate whether the CoCr+polyethylene film of the present invention obtained as described above is amorphous, X-ray and electron diffraction were performed, and the X-ray diffraction revealed that 20=206
No peak was observed in the range of ~100', and electron diffraction revealed only two halo rings, indicating that the material was amorphous.

・On the other hand, in the CoCr single film, there is a sharp peak at 20=44.2° due to the (002) structure of the hcp structure, and the electric current r-
In line diffraction, a diffraction pattern is obtained due to the hcp structure,
It was found that the CoCr'F integral film becomes crystalline.

CoCr+polyethylene film according to the present invention and Co of the control example
The magnetic properties of the Cr'11 monolithic film were measured. The saturation magnetic flux density Bs and the coercive force He were measured with a test↑1 vibrating magnetometer, and the anisotropic magnetic field Hk was measured with a torque meter. 4
! The results are shown in Table 1 below.

and 1 In the table, the coercive force is the in-plane measurement value, and the anisotropic magnetic field is the in-plane measurement value for the Go-Cr-PE film.
For the Cr film, the values are measured in the east direction.

As is clear from the results listed in Table 1, the amorphous CoCr+polyethylene film of the present invention exhibits soft magnetic properties. Therefore, it can be used as a z:1 magnetic permeability film in a two-layer media. Can be done.

Next, a CoCr-polyethylene film with a thickness of 8000 mm was prepared on the polyimide film 2, and the CoCr-polyethylene film was
A Cr film with a thickness of 2000 mm was fabricated to produce a two-layer film medium.

For comparison, permalloy film (
A two-layer film medium was also prepared in which a Ni-Fe film was deposited to a thickness of 8000 nm and a CoCr film was deposited to a thickness of 2000 nm.

As a high magnetic permeability layer, a CoCr film is used, one is an amorphous soft magnetic film obtained by the simultaneous vacuum evaporation method of CoCr and Borier thin film according to the present invention, and the other is a permalloy film.
The degree of C-axis orientation of the film is the half value ltJΔθs of the rocking curve of the (002) CoCr film.

When compared with CoCr-polyethylene film 1-
ΔIsO of the CoCr film when the CoCr film is formed on the permalloy film 1 is IO''~15°, but when the CoCr film is formed on the permalloy film
Δ05θ of CoCr film is 20° when r film is formed.
There is also -.

CoC was used as a high permeability film to investigate the recording and reproducing characteristics.
A 5-inch floppy disk was made from a medium using r-polyethylene film and a medium using permalloy film, and J
The measurement was carried out using an auxiliary magnetic pole excitation type head with an E magnetic pole thickness of 0.8 μm, 1 main magnetic pole + 1300 μm, and a coil winding number of 407. The results obtained are shown in Table 2 below.

In the table, 7kfci refers to the recording state in which magnetization is reversed 7000 times per inch, and Dsθ refers to this 7kfci.
It means the recording density when the +M output value at i is reduced to half, and the larger the value of 050, the higher the possibility of high-density recording.

In this way, by using an amorphous soft magnetic film formed by simultaneous vacuum deposition of CoCr and polyethylene as a high magnetic permeability film, compared to a permalloy film, even when the same vacuum deposition method is used, the crystallization of the CoCr film is reduced. The degree of orientation is improved, and therefore a commercial magnetic recording medium with excellent recording I11 characteristics can be obtained.

Perpendicular magnetic recording in which a CoCr-polyethylene film is formed as a high magnetic permeability layer on the substrate-1- using a continuous vacuum evaporation apparatus as shown in Fig. 2, and a CoCr film is formed on the first layer. A two-layer membrane medium was prepared.

Light blue condition (1) (&: polyimide film (film thickness 40 μm)
(2) Can temperature: 150°C (3) 1° [Evacuation degree: CoCr-polyethylene film forming chamber 5xlO-5 Torr CoCr film-forming chamber 4xlO°-6 Torr (4) Vapor deposition rate: CoCr-polyethylene L/7 film 6
00 people/5ee CoCr membrane 180 people/5ee (5) Membrane pressure: CoCr-polyethylene membrane 5000 peopleC
For comparison of 2,000 oCr films, a double-layer film medium using a permalloy amorphous film as a high magnetic permeability film was fabricated using a continuous sputtering apparatus as shown in FIG.

Sputtering conditions (1) Substrate: Polyimide film (g thickness 40 μm) (2
) Can temperature = 150°C (3) Argon pressure: 10 mTorr (4) Sputter rate: Permalloy 10 people/5eeCoCr
10 people/5ec (5) Membrane pressure: Permalloy 5000 people CoCr
Table 3 of the 2,000-person record compares the characteristics of two-layer media when a conventional permalloy film is used as a high magnetic permeability film and when a CoCr-polyethylene film of the present invention is used. Also,
Recording and reproducing characteristics were examined using a 5-inch floppy disk in the same manner as in Example 1.

The results are also shown in Table 3.

As described above, by using a C0Cr-polyethylene film as a high magnetic permeability film, a perpendicular magnetic recording medium having almost the same recording characteristics as the sputtering method can be manufactured by the vacuum evaporation method.

Five-inch floppy disk 1 A 5-inch floppy disk was prepared from a two-layer film medium using the permalloy film produced in the comparative example of Example 2 and the CoCr-polyethylene film of the present invention, and its corrosion resistance was examined.

Recording was performed on the outermost track in advance at a recording density of 50 kBPI, and a 1% NaCl aqueous solution was uniformly sprayed, and then 3
It was left in a constant temperature bath at 0°C. This disk was taken out every 111 times, 111 raw was performed, and the change in the +rg raw signal intensity was examined. 11) When subjecting the sample to the Fremby disk device to examine raw strength, the salt water on the surface was wiped off, and after the evaluation, salt water was sprayed again and the sample was returned to the constant temperature bath.

The measurement results are shown in Figure 4.

As is clear from the attached FIG. 4, C of the present invention.

The base high permeability layer made of a Cr-polyethylene amorphous film shows almost no change in reproduction output, whereas the FIT raw output of a permalloy film produced by a conventional sputtering method changes over time.

Therefore, it is better to use the CoCr-polyethylene amorphous film of the present invention as the base high permeability layer in terms of corrosion resistance.

[Effects of the Invention] As explained below, the present invention uses a polymer-impregnated amorphous soft magnetic film obtained by a simultaneous paper deposition method of a ferromagnetic metal and a polymer as a high magnetic permeability film. As a result, the orientation of the recording magnetic layer explained in 1-1 is not disturbed, so it is possible to realize a two-layer film medium for perpendicular magnetic recording that has excellent recording properties and corrosion resistance, and also has extremely high productivity. realizable.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams illustrating examples of batch and continuous vacuum deposition equipment used to produce the bilayer membrane of the present invention, respectively, and FIG. FIG. 4 is a schematic diagram showing an example of a continuous sputtering apparatus used for manufacturing the medium. FIG. It is a characteristic diagram showing the change in output with respect to the number of days of exposure to salt water for comparing corrosion resistance. 1.15 and 24...Crucibles for ferromagnetic metals. 2 and 14... Polymer crucible, 3... Substrate. 4... Substrate holder, 5... Substrate heater. 6...1'' [Empty tank, 7.18 and 26... Vacuum exhaust system. 8... Base film, 10... High magnetic permeability film production room. 11... Delivery roll, 12 and 22 ...Can roll, 13 and 23...Mask, 20...Perpendicular magnetic anisotropic film production room, 31...High magnetic permeability material target.

Claims (3)

[Claims] (1) In a two-layer medium for perpendicular magnetic recording in which a soft magnetic high permeability layer is provided on a nonmagnetic substrate and a perpendicular magnetic anisotropic film is laminated thereon, the soft magnetic high permeability layer is A two-layer film medium for perpendicular magnetic recording, characterized in that it is a soft magnetic film containing a magnetic metal and a polymer. (2) The two-layer film medium for perpendicular magnetic recording according to claim 1, wherein the polymer has a carbon atom number in the range of 10 to 1000. (3) The two-layer film medium for perpendicular magnetic recording according to claim 1, which contains a polymer in an amount of 5 vol% or more and 60 vol% or less.