JPH0760768B2 - 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 structure having excellent 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, the storage media used for fixed magnetic disks used as computer peripherals are from the coating type in which gamma iron oxide-based acicular magnetic powder is coated on a conventional aluminum disk substrate to the plating method. The density has been increased by changing to a thin film type of Co-Ni / Cr alloy by the sputtering method or sputtering method.

However, since the Co-Ni / Cr thin film is an alloy, there is a problem in durability, so the structure of the magnetic disk is (lubricating layer / protective layer / Co-Ni magnetic layer / Cr layer / Ni-P plating). It has a 6-layer structure (layer / aluminum substrate) and has a drawback that the manufacturing process is complicated.

Further, since the fixed magnetic disk is an in-plane recording 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, on the magnetic recording system, as a magnetic recording medium that enables perpendicular recording, which is a recording system that improves the above-mentioned drawbacks,
Although the magnetic head and the medium are in contact with each other, research on Co-Cr thin film medium has been actively conducted. However, as in the case of Co-Ni / Cr thin film media, since it is an alloy in Co-Cr media, there is a problem in reliability, so an amorphous carbon film or a protective layer of Co oxide is provided on the surface of the Co-Cr thin film. Must-have.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In a fixed magnetic disk device, it is necessary to reduce the running height (flying height) of a magnetic head with respect to a magnetic disk as much as possible to reduce output loss (spacing loss) due to the magnetic head and the magnetic disk spacing. As a result, the recording density is improved. Therefore, recently, in order to enable a high recording density, it is required to travel at a flying height amount of about 0.05 to 0.1 μm.

However, in any of the above Co-Ni / Cr thin film media and Co-Cr thin film media, there is a problem with durability, etc., so a protective film (several hundred Å) must be formed on the thin film surface to ensure reliability. , Spacing loss will inevitably increase.

Further, in the case of a fixed magnetic disk, since the magnetic disk is rotated at a high speed (3600 rotations / minute), the hardness of the magnetic layer is also very important in terms of ensuring reliability. However, in the case of alloys such as Co-Cr thin films, there is a problem in hardness.

In view of the above problems, the present invention provides a component of perpendicular magnetic recording having excellent reliability and capable of high-density magnetic recording, rather than a conventional alloy-based magnetic thin-film disk requiring a protective film on the thin film surface. The present invention provides a structure of a fixed magnetic disk and a manufacturing method thereof.

Means for Solving the Problems In order to solve the above problems, the present invention forms a Ni oxide film having a NaCl-type crystal structure preferentially oriented in (100) on a disk substrate, and further forms a cobalt having a columnar structure. And a fixed magnetic disk having a structure in which an iron oxide film having a spinel type crystal structure is formed, and a structure in which the fixed magnetic disk is manufactured by a manufacturing method using plasma activity and a CVD reaction.

Action Since the present invention is the structure and manufacturing method of the fixed magnetic disk having the above-mentioned structure, it is excellent in reliability such as durability and hardness and capable of high density magnetic recording as compared with the conventional alloy-based magnetic thin film disk. Is a structure of a fixed magnetic disk having a component of perpendicular magnetic recording, which is relatively easy to manufacture.

Example Hereinafter, a method of manufacturing a fixed magnetic disk by a plasma CVD method and an electromagnetic conversion characteristic according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic view of a plasma CVD apparatus in one embodiment of the present invention. In FIG. 1, 1 is a reaction chamber, 2 is an electrode, 3 is an exhaust system for maintaining a low pressure in the reaction chamber, 4 is a base substrate (glass disk substrate), 5 is a high frequency power source (13.56 MHz), 6, 7 , 8 are vaporizers containing raw materials, 9,10,11 are valves for controlling whether carrier gas is introduced into the vaporizer, 12,13,14 are reaction chambers for raw material gas and carrier gas A carrier gas cylinder (nitrogen), 16 a reaction gas cylinder (oxygen), and 17 a substrate heating heater with a substrate rotating mechanism.

Starting materials include iron acetylacetonate [Fe (C ₅ H ₇ O ₂ ) ₃ ], nickel acetylacetonate [Ni (C ₅ H ₇ O ₂ ) ₂ xH ₂ O], and cobalt acetylacetonate [Co ( C ₅ H ₇ O ₂ ) ₃ ] was used.

Vaporizer 6 Dehydrated nickel acetylacetonate (100 ° C in air for 2 hours), cobalt acetylacetonate 7 and iron acetylacetonate 8 are heated to 180 ° C, 130 ° C and 120 ° C, respectively. Keep it. Open valves 9 and 12 and introduce nickel acetylacetonate vapor and oxygen (flow rate 5 SCCM) together with nitrogen carrier (flow rate 30 SCCM) into the reaction chamber 1 whose pressure is reduced by the exhaust system 3 to generate plasma (power 1.5 W / cm ² )
The reaction was performed under reduced pressure (0.08 Torr) for 5 minutes, a NiO film was formed on a glass disk substrate (120 rpm) heated to 400 ° C., and valves 9 and 12 were closed.

Further, without breaking the vacuum, the valves 10, 11, 13, 14 were opened, and the carrier gas (flow rate 3 SCCM on the vaporizer 7 side, flow rate 8 SCCM on the vaporizer 8 side) as well as cobalt acetylacetonate and iron acetylacetonate Introduce steam into the reaction chamber 1 and move in plasma (power 1.5 W / cm ² ) for 15
The reaction was performed under a reduced pressure (0.06 Torr) for a minute to form a Co ferrite film on the NiO film to form a Co ferrite / NiO bilayer film.

Then, the glass disk substrate on which the bilayer film was formed was taken out of the vacuum chamber, the same bilayer film was formed on the back surface in the same manner, and Co ferrite / N with magnetic thin film surfaces on both sides was formed.
An iO disk was made.

Next, a fixed magnetic disk was prepared by immersing this disk in a liquid tank containing a fluorine-based organic lubricant and applying it.

The produced fixed magnetic disk of the present invention has a gap length (G
Using a MIG head with L) of 0.25 μm and track width (Tw) of 10 μm, a head current value of 50 mA was selected and the electromagnetic conversion characteristics were evaluated. The fixed magnetic disk was rotated at a speed of 3600 rpm and the evaluation was performed on a circumferential track of 20.0 mm from the center of the disk. The relative speed between the fixed magnetic disk and the magnetic head was 7.5 m / sec, and the flying height of the magnetic head was 0.15 μm.

Next, for comparison, a magnetic layer thickness of Hc = 1.0 kOe and Ms = 800 emu / cc of 800 Å, a carbon film of 600 Å was formed on it as a protective layer, and the same lubricant film layer as the present invention was formed. Conventional Co-Ni / Cr alloy thin film fixed magnetic disk (with in-plane magnetization orientation on aluminum substrate) and Co ferrite magnetic film directly on the glass disk substrate The same) was formed on the Co ferrite disk, and the electromagnetic conversion characteristics were evaluated under the same conditions as the fixed magnetic disk of the present invention.

The obtained fixed magnetic disk of the present invention, Co-Ni / Cr and C
Figure 2 shows the relationship between the recording density and the reproduction output of a single-layer ferrite disk.

In FIG. 2, the horizontal axis represents the recording density (recording wavelength) and the vertical axis represents the reproduction output. Further, (a) is the fixed magnetic disk of the present invention, (b) is a Co—Ni / Cr alloy thin film fixed magnetic disk for comparison, and (c) is a Co ferrite thin film fixed magnetic disk (Co ferrite single layer for comparison). Film) characteristics.

From FIG. 2, the fixed magnetic disk of the present invention is
It can be seen that the reproduction output shows a higher value on the high recording density side in the short wavelength region than the Ni / Cr or Co ferrite single layer disc. That is, it is understood that the fixed magnetic disk of the present invention can cope with high recording density. When the reproduced waveform of the recording signal of the fixed magnetic disk of the present invention was observed with an oscilloscope, a dipulse waveform, which is a characteristic of including a perpendicular magnetic recording component, was shown.

After the measurement of the electromagnetic conversion characteristics, the lubricant film layer was removed using an organic solvent, and the crystal structure of the Co ferrite / NiO disk was analyzed by X-ray diffraction.

Further, for comparison, a sample film in which only a NiO film was formed on the glass disk substrate under the above-mentioned film forming conditions and a sample film in which only a Co ferrite film was formed on the glass disk substrate under the above-mentioned conditions were prepared respectively. The crystal structure was analyzed by X-ray diffraction.

As a result, the NiO film formed under the above conditions was X-ray (100)
Was perfectly oriented. Also, NiO (100) as the underlayer
By using the perfect orientation film, the (100) orientation of the Co ferrite film, which is the magnetic layer, is affected by the crystal orientation of the underlayer, and is improved compared to when it is directly formed on the glass disk. It was

In addition, the Co ferrite / NiO disk was destroyed and the surface and fracture surface of the disk were observed using a high resolution scanning electron microscope. As a result, it was found that the double-layered film of this disc had a columnar structure, the film thickness was about 4500Å, and the column diameter was 400 to 600Å. In addition, as a result of observing the sample film and the sample film with a scanning electron microscope in the same manner, the Ni
The O film had a film thickness of about 2000Å, and the sample Co ferrite film had a film thickness of 2500Å.

Furthermore, Co ferrite by X-ray microanalyzer
As a result of analyzing the composition of the / NiO disk, Co / Fe was 5/95.

Next, the magnetic characteristics of the Co ferrite / NiO disk were measured by a vibrating sample magnetometer (VSM). As a result, the coercive force of the disk is Hc⊥ ＝ 1.2kOe, Hc ＝ 780Oe
Met. The Ms of Co ferrite / NiO bilayer film is 275emu.
It was / cc.

From these facts, the fixed magnetic disk of the present invention has a higher recording density side in the shorter wavelength region than the Co ferrite single layer disk,
The reason why the reproduction output is high is that the (100) -oriented NiO film is used as the underlayer,
0) This is probably because the orientation was increased.

EFFECTS OF THE INVENTION As described above, the present invention forms a (100) oriented Ni oxide film having a NaCl type crystal structure as an underlayer on a disk substrate,
Further, since the structure of the fixed magnetic disk is formed by forming a spinel-type iron oxide magnetic thin film containing Co having a columnar structure as the magnetic layer, it is possible to achieve high reliability and high recording density.

Further, since the plasma CVD method is used as the manufacturing method, the two-layer film can be simply and continuously manufactured by simply controlling the supply of the raw material.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a plasma CVD apparatus in one embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the recording density and the reproduction output of the fixed magnetic disk of the present invention in the embodiment. 1 ... Reaction chamber, 2 ... Electrode, 3 ... Exhaust system, 4
…… Glass disk substrate, 5 …… High frequency power supply, 6,7,8…
… Vaporizer, 9,10,11 …… Carrier gas supply valve, 12,1
3, 14 …… Raw material gas supply valve, 15 …… Carrier gas cylinder, 16 …… Reaction gas cylinder, 17 …… Substrate heating heater.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masuzou Hattori 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-63-181305 (JP, A)

Claims (5)

[Claims] 1. A structure in which an oxide thin film having a NaCl type crystal structure is formed on a disk substrate, and an iron oxide magnetic thin film having a spinel type crystal structure containing cobalt is further formed on the oxide thin film. Characteristic fixed magnetic disk. 2. The fixed magnetic disk according to claim 1, wherein the oxide thin film having a NaCl type crystal structure is nickel oxide crystallographically (100) preferentially oriented. 3. The fixed magnetic disk according to claim 1, wherein the iron oxide thin film having a spinel type crystal structure containing cobalt has a columnar structure in a direction perpendicular to the disk substrate surface. 4. A nickel-oxide thin film having a NaCl type crystal structure is chemically vapor-deposited on a disk substrate by decomposing a mixed gas of vapor of an organometallic compound containing nickel and oxygen using plasma, and further iron is added. A mixed gas of an organometallic compound vapor containing cobalt and an organometallic compound vapor containing cobalt and oxygen is decomposed using plasma to chemically form a spinel-type iron oxide thin film containing cobalt on the nickel oxide thin film. A method for manufacturing a fixed magnetic disk, which comprises vapor deposition. 5. The fixed magnetic disk according to claim 4, wherein the organometallic compound containing nickel, the organometallic compound containing iron and the organometallic compound containing cobalt are β-diketone metal complexes. Manufacturing method.