JP2538123B2 - Fixed magnetic disk and manufacturing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed magnetic disk excellent in reliability and capable of supporting high-density magnetic recording, and a manufacturing method thereof.

2. Description of the Related Art In an advanced information society in recent years, the amount of information to be stored has been increasing year by year, and there has been an increasing demand for larger capacity and higher density of storage devices.

Under these circumstances, storage media used for fixed magnetic disks used as computer peripherals are
The conventional coating type in which gamma iron oxide-based acicular magnetic powder is coated on an aluminum disk substrate has been changed to a Co-Ni / Cr alloy thin film type by the plating method or sputtering method. Has been.

However, the Co-Ni / Cr alloy thin film type has a problem in durability since its constituent material is an alloy, and as a structure of the fixed magnetic disk, there are (lubricating layer / protective layer / Co -Ni magnetic layer / Cr layer
/ Ni-P plating layer / aluminum substrate) has a five-layer structure, and has a drawback that the manufacturing process is complicated.

FIG. 4 shows a cross section of a Co-Ni / Cr alloy thin film type fixed magnetic disk which is a conventional fixed magnetic disk. In the drawing, 1 is an aluminum substrate, 2 is a Ni-P plated layer, and 3 is Cr layer, 4 Co-Ni magnetic layer, 5 protective layer, 6
Is a lubricating layer.

In the conventional fixed magnetic disk, since the Co—Ni magnetic layer 4 is an in-plane storage medium, if the recording wavelength is shortened to further increase the recording density, recording becomes difficult due to the influence of the demagnetizing field.

Therefore, as a magnetic recording medium that enables perpendicular recording, which is a recording method in which the above-mentioned drawbacks are improved on the magnetic recording method, the magnetic head and the medium are in contact with each other. Has been actively researched. However, as in the case of the thin film type recording medium of Co-Ni / Fr alloy shown in FIG. 4, the Co-Cr thin film medium also has a problem in reliability because it is an alloy, and amorphous carbon is present on the surface of the Co-Cr thin film. A protective layer 5 such as a film or Co oxide must be provided.

On the other hand, in a fixed magnetic disk device, reducing the running height (flying height) of the magnetic head with respect to the magnetic disk as much as possible reduces the output loss (spacing loss) due to the magnetic head and magnetic disk spacing. This will lead to an increase in density. Recently, in order to enable high recording density, 0.05-0.1 μm
It is necessary to drive at a flying height of a certain amount.

However, both the conventional Co—Ni / Cr alloy thin film type recording medium and the Co—Cr thin film type recording medium have problems in durability and the like, and therefore a protective layer 5 is formed on the surface of the thin film medium to ensure reliability. (Number 100Å) must be formed,
Therefore, there remains a problem that spacing loss increases.

The present invention is to solve the above problems, and an object of the present invention is to provide a fixed magnetic disk having a component of perpendicular magnetic recording that is excellent in reliability and is compatible with high density magnetic recording, and a method for manufacturing the same. Is.

Means for Solving the Problems In order to achieve the above object, the present invention forms an X-ray alumophous oxide thin film on a disk substrate, and spin-type iron oxide soft magnetic of spinel type crystal structure on the oxide thin film. A fixed magnetic disk having a three-layer structure in which a thin film is formed and a spinel-type iron oxide magnetic thin film containing cobalt having a columnar structure and having a columnar structure is further formed on the fixed magnetic disk. It is produced by a production method utilizing a reaction.

Action According to the present invention, therefore, the iron oxide soft magnetic thin film on the X-ray amorphous oxide thin film formed on the disk substrate forms a horseshoe-shaped magnetic path with the iron oxide magnetic thin film containing cobalt. Excellent in reliability and hardness, and high density magnetic recording is possible.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of a fixed magnetic disk in one embodiment of the present invention. In the figure, 7 is a disk substrate, 8 is a CoZnFe oxide film layer, 9 is a Mn-Zn ferrite film,
10 is a Co ferrite film, and 11 is a lubricating layer.

FIG. 2 is a schematic diagram of a plasma CVD apparatus used for manufacturing a fixed magnetic disk in one embodiment of the present invention, in which 12 is a reaction chamber, 13 is an electrode, and 14 is an electrode.
Is an exhaust system for maintaining a low pressure in the reaction chamber, 15 is a high frequency power source (13.56MHz), 16 to 19 are vaporizers containing raw materials, and 20 to 23 are vaporizers of carrier gas into the vaporizers 16 to 19. A first valve for controlling the presence / absence of introduction, 24-27 are second valves for controlling the presence / absence of introduction of the source gas and the carrier gas into the reaction chamber 12, 28 is a carrier gas cylinder (nitrogen), 29 is a reaction gas cylinder (oxygen), and 30 is a substrate heating heater with a substrate rotating mechanism.

Next, a method of manufacturing the fixed magnetic disk of this embodiment will be described.

As a starting material, iron acetylacetonate [Fe (C ₅ H ₇
O ₂ ) ₃ ], manganese acetylacetonate [Mn (C ₅ H
₇ O ₂ ) ₃ ], zinc acetylacetonate [Zn (C ₅ H ₇ O ₂ )
₂ · 2H ₂ O], cobalt acetylacetonate [Co (C ₅ H ₇
O ₂ ) ₃ ] was used to dehydrate the vaporizer 16, and zinc acetylacetonate (2 hours at 100 ° C. in air), vaporizer 1
Put manganese acetylacetonate in 7, a cobalt acetylacetonate in a vaporizer 18, and iron acetylacetonate in a vaporizer 19, and heat and keep at 75 ° C, 130 ° C, 120 ° C, and 135 ° C, respectively. The first valves 20, 22, 23 and the second valves 24, 26, 27 are opened, and the vapors of acetylacetonate of zinc, cobalt, and iron are used as reaction gases together with the nitrogen carrier gas (flow rate of 10 SCCM). (Flow rate 2SCCM) is introduced into the reaction chamber 12 whose pressure is reduced by the exhaust system 14, and plasma is generated (electric power).
1.5 W / cm ²⁾ is, the reaction was carried out in 2 minutes under reduced pressure (0.10 Torr), the disc substrate 7 made of glass or the like which is heated to 400 ° C.
The CoZnFe oxide film 8 is formed on (120 rpm) and the first
Valve 22 and the second valve are closed.

Subsequently, the first valve 21 and the second valve 25 were opened, and zinc acetylacetonate vapor and manganese acetylacetonate vapor and iron acetylacetonate were introduced together with the nitrogen carrier gas (flow rate 10 SCCM in vaporizers 16, 17, and 19 respectively). Oxygen as a reaction gas from the steam of nato (flow rate 5SCCM)
In addition, the gas was introduced into the reaction chamber 12 whose pressure was reduced by the exhaust system 14, plasma was generated (power 1.5 W / cm ² ), the reaction was performed under reduced pressure (0.9 Torr) for 5 minutes, and heated to 400 ° C. (120 rpm) Mn-Zn ferrite film 9 on top
Is formed, and the first valve 21 and the second valve 25 are closed.

Further, subsequently, the first valves 22 and 23 and the second valves 26 and 27 are opened, and the vapor of cobalt acetylacetonate and the vapor of iron acetylacetonate are introduced together with the nitrogen carrier gas (the vaporizers 18 and 19 respectively have a flow rate of 10 SCCM). Reaction with oxygen (flow rate 5 SCCM) as a reaction gas in plasma (power 1.5 W / cm ² ) for 8 minutes under reduced pressure (0.07 Torr) to form Mn-Zn ferrite film 9 and Co ferrite film 10. Then, a three-layer film of Co ferrite / Mn-Zn ferrite / CoZnFe oxide was formed.

Then, the disk substrate 7 on which the three-layer film is formed is taken out from the reaction chamber 12, a three-layer film having the same structure is formed on the back surface by the same method, and Co ferrite / Mn-Zn having magnetic thin film surfaces on both sides is formed. After making a ferrite / CoZnFe oxide disk and then heat treating this disk in air at 300 ° C for 3 hours, submerge it in a liquid tank (not shown) containing a fluorine-based organic lubricant to form a lubricating layer. A fixed magnetic disk was produced by applying 11.

The thus-obtained fixed magnetic disk of this example had a gap length (GL) of 025 μm and a track width (Tw) of 1
Using a 0 μm MIG head, a head current value of 50 mA was selected and the electromagnetic conversion characteristics were evaluated. 36 fixed magnetic disks
Rotate at a speed of 00r.pm, 20.0mm from the center of the disc
The evaluation was carried out on a circular track. The relative speed between the fixed magnetic disk and the magnetic head was 7.5 / sec, and the flying height of the magnetic head was 0.15 μm.

Next, for comparison, C with Hc = 1.0 kOe and Ms = 800 emu / cc
The thickness of the magnetic layer consisting of the r layer 3 and the Co-Ni magnetic layer 4 is 800Å
Then, a carbon film of 600 Å is formed thereon as a protective layer 5, and a conventional Co-Ni / Cr layer having the same lubricating layer 6 as the present invention is provided.
Alloy thin film type fixed magnetic disk (aluminum substrate magnetized and oriented in the in-plane direction) and a structure in which a Co ferrite magnetic film (manufacturing conditions are the same as those of the three-layer film) are directly formed on the glass disk substrate. A Co ferrite thin film fixed magnetic disk was prepared, and the electromagnetic conversion characteristics were measured under the same conditions as the fixed magnetic disk of this example.

The fixed magnetic disk of this example thus obtained and the conventional fixed magnetic disk of Co--Ni / Cr alloy thin film and C
Fig. 3 shows the relationship between the reproduction output and recording density or recording wavelength of a ferrite thin film fixed magnetic disk.

In FIG. 3, the horizontal axis represents recording density or recording wavelength,
The vertical axis is the reproduction output. Further, in the figure, (a) is the fixed magnetic disk of this embodiment, and (b) is a conventional Co- disk for comparison.
The Ni / Cr alloy thin film fixed magnetic disk and (c) show the characteristics of another conventional Co ferrite thin film fixed magnetic disk (Co ferrite single layer film), respectively.

From FIG. 3, the fixed magnetic disk of the present embodiment is a conventional Co-
Compared to the Ni / Cr alloy thin film fixed magnetic disk and Co ferrite thin film fixed magnetic disk, the playback output is higher overall, and it can be seen that higher recording density can be supported.

When the reproduction waveform of the recording signal of the fixed magnetic disk of this embodiment is observed with an oscilloscope, a dipulse waveform that is characteristic of including a perpendicular magnetic recording component is shown.

After the measurement of the electromagnetic conversion characteristics, for comparison, a CoZnFe oxide film 8, a Co ferrite film 10, a Mn-Zn ferrite film 9 or a Mn film was formed on a glass disk substrate under the same conditions as in the above-mentioned embodiment.
A two-layer film made of -Zn ferrite / Co ferrite was prepared, and an analysis was performed together with a fixed magnetic disk made of a three-layer film of Co ferrite / Mn-Zn ferrite / CoZnFe oxide.

First, the CoZnFe used as the underlying layer was analyzed by X-ray diffraction.
As a result of the analysis of the crystal structure of the oxide film 8, the CoZnFe oxide film 8 produced under the above conditions was X-ray amorphous.

Next, the fixed magnetic disk consisting of a three-layer film of Co ferrite / Mn-Zn ferrite / CoZnFe oxide was destroyed, and the surface and fracture surface of the fixed magnetic disk were observed using a high-resolution scanning electron microscope (SEM). did. As a result, the Co ferrite film 10 has a columnar structure, a film thickness of about 4100Å and a column diameter of 50.
It was found to be 0-600Å.

Moreover, as a result of observing the Co ferrite / Mn-Zn ferrite two-layer film by SEM, columnar growth was found to be columnar with a film thickness of 3500Å, but a column diameter of 450 to 800. That is, it is understood that by forming the amorphous CoZnFe oxide film 8 as the base film, it is possible to reduce the average column diameter of the magnetic layer formed of the Co ferrite film 10 and to reduce the size distribution.

Furthermore, by electron beam microanalyzer (EPMA)
As a result of analyzing the compositions of the Mn-Zn ferrite film 9 and the Co ferrite film 10, Mn / Zn / Fe = 7/3/20 and Co / Fe = 1/1, respectively.
It was 9.

Next, the Mn-Zn ferrite film 9 / CoZnFe oxide film 8 and
The magnetic characteristics of the Co ferrite film 10 were measured by a vibrating sample magnetometer (VSM). As a result, Mn-Zn
The ferrite film 9 had Hc = 20 Oe and Ms = 320 emu / cc, and the Co ferrite film 10 had Hc | = 1200 Oe and Ms = 274 emu / cc.

The fixed magnetic disk of the present example has a higher reproduction output on the high recording density side in the short wavelength region than the conventional Co--Ni / Cr alloy thin film magnetic disk because it contains the perpendicular magnetic recording component. Moreover, the reason why the reproduction output is higher than that of the Co ferrite thin film fixed magnetic disk is that the soft magnetic material such as the Mn-Zn ferrite film 9 is used to form the horseshoe-shaped magnetic path with the Co ferrite magnetic layer. It is considered that this is because the influence of the demagnetizing field is reduced.

As a constituent material of the amorphous oxide thin film 8 or the iron oxide soft magnetic thin film 9 having the spinel type crystal structure, other elements shown in claims (2) and (3) were also examined, and as a result, Similar to the case of the fixed magnetic disk composed of the three-layered film of Co ferrite / Mn-Zn ferrite / CoZnFe oxide of the example, comparison with the conventional Co-Ni / Cr alloy thin film magnetic disk and Co ferrite thin film fixed magnetic disk was made. The overall playback output was high.

As described above, according to the above-described embodiment, the amorphous CoZnFe oxide film 8 is formed on the disk substrate 7, and Mn is formed thereon.
Since the -Zn ferrite film 9 is formed and the Co ferrite layer 10 having a columnar structure in the direction perpendicular to the surface of the disk substrate 7 is further formed thereon, the durability and hardness are excellent. Moreover, a fixed magnetic disk capable of high-density magnetic recording can be manufactured.

EFFECTS OF THE INVENTION As apparent from the above-described embodiments, the present invention forms an X-ray amorphous oxide thin film as an underlayer on a disk substrate, and spinel-type iron oxide soft magnetic thin film having a crystalline structure thereon. Of a fixed magnetic disk in which a spinel-type iron oxide magnetic thin film containing cobalt having a columnar structure in the direction perpendicular to the disk substrate surface is formed on top of this to form a highly reliable and high recording medium. Plasma CD can be used for density, and its manufacturing method is
Since the V method is used, there is an advantage that a three-layer film can be easily and continuously produced by simply controlling the supply of raw materials.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of an essential part of a fixed magnetic disk according to an embodiment of the present invention, and FIG. 2 is a schematic front cross-sectional view of a plasma CVD apparatus used to carry out the method for manufacturing the fixed magnetic disk. FIG. 4 is a characteristic diagram showing a comparison between the recording wavelength and recording density of the fixed magnetic disk of the embodiment and the conventional example and the reproduction output, and FIG. 4 is an enlarged cross-sectional view of a main part of the conventional fixed magnetic disk. 7 ... Disk substrate, 8 ... CoZnFe oxide film (amorphous oxide thin film), 9 ... Mn-Zn ferrite film (iron oxide soft magnetic thin film), 10 ... Co ferrite film (cobalt-containing spinel type crystal) Iron oxide magnetic thin film of structure).

Claims (5)

(57) [Claims] 1. An X-ray amorphous oxide thin film is formed on a disk substrate, an iron oxide soft magnetic thin film having a spinel type crystal structure is formed on the oxide thin film, and the iron oxide soft magnetic thin film is further formed on the iron oxide soft magnetic thin film. A fixed magnetic disk having an iron oxide magnetic thin film of spinel type crystal structure containing cobalt having a columnar structure perpendicular to the surface of the disk substrate formed thereon. 2. An X-ray amorphous oxide thin film comprises at least an element group of magnesium, calcium, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, strontium, niobium, cadmium and barium. The fixed magnetic disk according to claim 1, which contains one element. 3. The fixed magnetic disk according to claim 1, wherein the iron oxide soft magnetic thin film having a spinel type crystal structure contains at least one element selected from zinc, manganese and nickel. 4. An organometallic compound containing magnesium, an organometallic compound containing calcium, an organometallic compound containing titanium, an organometallic compound containing vanadium, an organometallic compound containing manganese, an organometallic compound containing iron, and cobalt. Organometallic compounds, organometallic compounds containing nickel, organometallic compounds containing copper, organometallic compounds containing zinc, organometallic compounds containing strontium, organometallic compounds containing niobium, organometallic compounds containing cadmium,
A gas mixture of at least one organometallic compound of barium-containing organometallic compounds and oxygen is reacted with plasma to chemically deposit an X-ray amorphous oxide thin film on a disk substrate, and zinc is further added. Reaction of a vapor of at least one organometallic compound of an organometallic compound containing manganese, an organometallic compound containing manganese, and a nickel, and a mixed gas of an organometallic compound containing iron and oxygen using plasma Then, an iron oxide soft magnetic thin film having a spinel type crystal structure is formed on the oxide thin film, and a mixed gas of a vapor of an organometallic compound containing iron, a vapor of an organometallic compound containing cobalt and oxygen is further used by plasma. Of a fixed magnetic disk, which is decomposed by chemical vapor deposition of an iron oxide magnetic thin film having a spinel type crystal structure containing cobalt on the iron oxide soft magnetic thin film. Production method. 5. An organometallic compound containing magnesium, an organometallic compound containing calcium, an organometallic compound containing titanium, an organometallic compound containing vanadium, an organometallic compound containing manganese, an organometallic compound containing iron, and cobalt. Organometallic compounds, organometallic compounds containing nickel, organometallic compounds containing copper, organometallic compounds containing zinc, organometallic compounds containing strontium, organometallic compounds containing niobium, organometallic compounds containing cadmium and organic containing barium. The method for producing a fixed magnetic disk according to claim 4, wherein the metal compound is a β-diketone-based metal complex.