JPH04184709A - Fixed magnetic disk and manufacture thereof - Google Patents

Abstract

PURPOSE:To make the title disk excellent in reliability in durability, hardness, etc. and to make it capable of executing high-density magnetic recording by a method wherein both a soft magnetic thin film of an iron oxide on a thin film of an oxide formed on a disk substrate, and a magnetic thin film of the iron oxide formed thereon and containing cobalt are made to have a spinel structure. CONSTITUTION:A soft magnetic thin film 8 of an iron oxide, such as Mn-Zn ferrite or Ni-Zn ferrite, which has a spinel structure is formed as a ground layer on a disk substrate 7, and further a magnetic thin film 9 of a spinel-type iron oxide having a columnar structure and containing cobalt is formed as a magnetic layer. A plasma CVD method is employed for manufacture thereof. A disk manufactured according to this constitution is excellent in the reliability in durability, hardness, etc. and makes it possible to execute high-density mag netic recording.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fixed magnetic disk that has excellent reliability and is compatible with high-density magnetic recording, and a method for manufacturing the same.

2. Description of the Related Art In the recent advanced information society, the amount of information to be stored continues to increase year by year, and the demand for larger capacity and higher density storage devices is also increasing.

Under these circumstances, the storage media used in fixed magnetic disks used as computer peripherals have changed from the conventional coating type, in which gamma iron oxide acicular magnetic powder is coated on an aluminum disk substrate, to the plating method. It changed to a thin film type of Co-Ni/Cr alloy by sputtering method, etc.
Efforts have been made to increase density.

Problems to be Solved by the Invention However, since the Co-Ni/Cr alloy thin film type is composed of an alloy, there are problems with durability, etc.; Co
Ni magnetic layer/Cr layer/Ni-P plating layer/
It has a five-layer structure (aluminum substrate), and has the disadvantage that the manufacturing process is complicated.

Figure 4 shows a conventional fixed magnetic disk, Co-Ni.
/ This shows a cross section of a thin-film type fixed magnetic disk made of Cr alloy. In the figure, l is an aluminum substrate, 2 is an N1-P plating layer, 3 is a Cr layer, 4 is a Co-Ni magnetic layer, and 5 is a protection Layer 6 is a lubricating layer.

Since the above-mentioned conventional fixed magnetic disk is a recording medium in which the Co-Ni layer 4 is in-plane, 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 that improves the above drawbacks on the magnetic recording method,
Although the magnetic head and its medium are in a contact state, research has been actively conducted on Co--Cr thin film media and the like. However, as in the case of the Co-Ni/Cr alloy thin film type recording medium shown in Fig. 4, the Co-Cr thin film medium also has reliability problems because it is an alloy. The problem is that a protective layer 5 such as a film or CO oxide must be provided.

On the other hand, in fixed magnetic disk drives, the running height (flying hide) of the magnetic head relative to the magnetic disk should be made as low as possible in order to reduce the output loss (spacing loss) caused by the magnetic head and magnetic disk spacing. , which leads to an improvement in recording density, and recently, in order to enable high recording density, 0.05 to 0.
It is required to run with a flying hide amount of about 1 μm.

However, both the conventional Co-Ni/Cr alloy ** type recording medium and the Co-Cr thin film type recording medium have problems with durability, etc., so protection is provided on the surface of the medium to ensure reliability. The problem remains that five layers (several hundreds of people) must be formed, which inevitably increases spacing loss.

Furthermore, in the case of a fixed magnetic disk, since the magnetic disk is rotated at high speed (3600 revolutions/minute), it is very important to have a high hardness of the magnetic layer in order to ensure reliability. However, in the case of an alloy such as a Co--Cr thin film, there is a problem that the hardness is insufficient.

The present invention solves the above problems, and aims to provide a fixed magnetic disk having a perpendicular magnetic recording component that is highly reliable and capable of supporting high-density magnetic recording, and a method for manufacturing the same. It is.

Means for Solving the Problems In order to achieve the above object, the present invention forms an iron oxide soft magnetic thin film with a spinel crystal structure on a disk substrate, and further forms an iron oxide magnetic thin film with a spinel crystal structure containing cobalt. This is a fixed magnetic disk having a formed structure, and the fixed magnetic disk is manufactured by a manufacturing method utilizing plasma activation and CVD reaction.

Therefore, according to the present invention, the iron oxide soft magnetic thin film on the oxide thin film formed on the disk substrate and the iron oxide magnetic thin film containing cobalt formed thereon both have a spinel type crystal structure. Since it is preferentially oriented in (100), it has excellent reliability such as durability and hardness, and can perform high-density magnetic recording.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a fixed magnetic disk in an embodiment of the present invention, and in the figure, 7 is a disk substrate;
8 is a Mn-Zn ferrite film, 9 is a Co ferrite film,
10 is a lubricating layer.

FIG. 2 shows a schematic diagram of a plasma CVD apparatus used for manufacturing a fixed magnetic disk in an embodiment of the present invention. In the figure, 11 is a reaction chamber, I2 is an electrode, and 13 is a device that maintains a low pressure inside the reaction chamber. 14 is a high frequency power supply (13,56MHz), 15-1
8 is a vaporizer containing the raw material, 19 to 22 are first valves for controlling whether or not carrier gas is introduced into the vaporizers 15 to 18, and 23 to 26 are reaction chambers for the raw material gas and carrier gas. 27 is a carrier gas cylinder (nitrogen); 27 is a carrier gas cylinder (nitrogen);
8 is a reaction gas cylinder (oxygen), and 29 is a substrate heater equipped with a substrate rotation mechanism.

Next, the method of manufacturing the fixed magnetic disk of this embodiment will be explained based on FIG.

Iron acetylacetonate (Fe (C
, H, O□), ], Manganese acetylacetonate (M
n CC@H? Ox)s), zinc acetylacetonate [Zn (cs H?Ox)g ・2H
, O), cobalt acetylacetonate (C.

(C5H? (h)s), manganese acetylacetonate was placed in the vaporizer 15, and dehydrated zinc acetylacetonate was placed in the vaporizer 16 (2
time), put cobalt acetylacetonate in vaporizer 17 and iron acetylacetonate in vaporizer 18, and add 1 hour each to vaporizer 17.
Heat and hold at 30°C, 170″C, 120°C, 135°C. Flow rate 45 CCM on the vaporizer 16 side, flow rate 7 SCC? Oxygen (flow rate: 5 SCCM) was introduced into the reaction chamber 11 which was reduced in pressure by the exhaust system 13, plasma was generated (power: 1.5 W/di), and the reaction was carried out under reduced pressure (0.09 Torr) for 6 minutes. Conducted at 400°C
A disk substrate 7 (120
Mn--Zn ferrite film 8 is deposited on the rotational speed (revolutions per minute), and the first valve 19.20 and the second valve 23.24 are closed.

Then, without breaking the vacuum, the first valve 21 and the second valve 25 are opened, and nitrogen carrier gas (flow rate 8
Cobalt acetylacetonate vapor was introduced into the reaction chamber 11 along with iron acetylacetonate vapor (power: 1.5 W/cj
) for 8 minutes under reduced pressure (0.07 Torr),
A Co ferrite film 9 is formed on the Mn-Zn ferrite film 8 to form a two-layer film of Co ferrite/Mn-Zn ferrite.

Then, the disk substrate 7 on which the two-layer film was formed was taken out from the reaction chamber 11, and a two-layer film with the same structure was formed on the back side in the same manner, and a Co
A ferrite/MnZn ferrite disk was prepared, and then this disk was heat-treated in air at 300°C for 3 hours, and then placed in a liquid bath containing a fluorine-based organic lubricant (
A fixed magnetic disk was fabricated by submerging the disk in a liquid (not shown) and applying a lubricating layer 10.

The manufactured fixed magnetic disk of this example had a gap length (
GL) is 0.25 μm, track width (Tw) is 10 μm
The electromagnetic conversion characteristics were evaluated using a MIG head of 50 mA and a head current value of 50 mA.

A fixed magnetic disk was rotated at a speed of 360 Or, p, a+, and evaluation was performed on a circumferential track of 20.0 degrees from the center of the disk. Note that the relative speed between the fixed magnetic disk and the magnetic head was 7.5/sec, and the flying hide of the magnetic head was 0.15 μm.

Next, for comparison, HC = 1.0 kOe, Ms = 8
The thickness of the magnetic layer consisting of a Cr layer 3 of 00 emu/cc and a Co-NiTi2 layer 4 was 800 mm, on which a carbon film was formed as a protective layer 5 of 600 mm, and a lubricating layer 6 similar to that of the present invention was formed. The conventional Co-Ni/Cr alloy is
A fixed magnetic disk (aluminum substrate with magnetization oriented in the in-plane direction) and a glass disk substrate are directly coated with C.
o Ferrite magnetic film (film formation conditions are the same as for two-layer film)
A Co ferrite thin film fixed magnetic disk having a structure was prepared, and its 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 Co-Ni/Cr alloy III! FIG. 3 shows a comparison of the relationship between the recording density or the recording wavelength and the reproduction output of the fixed magnetic disk and the Co ferrite thin film fixed magnetic disk.

In FIG. 3, the horizontal axis represents recording density or recording wavelength, and the vertical axis represents reproduction output. In the same figure, (a) is the fixed magnetic disk of this embodiment, and b) is the conventional Co-N disk for comparison.
The characteristics of an i/Cr alloy thin film fixed magnetic disk, (e) another conventional Co ferrite fixed film magnetic disk, and an I film fixed magnetic disk (Co ferrite single layer) are shown, respectively.

, As can be seen from FIG. 3, the fixed magnetic disk of the present example exhibits a higher reproduction output value on the high recording density side in the short wavelength region compared to the conventional Co-Ni/Cr alloy thin film fixed magnetic disk.
When compared with the same conventional Co ferrite thin film fixed magnetic disk, the overall reproduction output is higher, indicating that it is possible to support higher recording densities.

Note that when the reproduced waveform of the recording signal of the fixed magnetic disk of this embodiment is observed with an oscilloscope, it shows a dipulse waveform, which is characterized by including a perpendicular magnetic recording component.

After the measurement of the electromagnetic conversion characteristics, the lubricating layer 10 of the fixed magnetic disk of this example was removed using an organic solvent, and the crystal structure of the Co ferrite film and the Mn-Zn ferrite film was analyzed by X-ray diffraction. It was found that the produced film had a spinel-type crystal structure and was preferentially oriented in (100).

Furthermore, the fixed magnetic disk of this example was destroyed and its surface and fractured surface were observed using a high-resolution scanning electron microscope (SEM). As a result, the two-layer film had a columnar structure, and the film thickness was approximately It was found that there were 3,500 people and the column diameter was 450-800 people. For comparison, a Mn--Zn ferrite film and C were formed on a glass disk substrate under the same conditions as in the above example.

A ferrite film was prepared and observed in the same manner using SEM. As a result, the M n -Z n ferrite film had a thickness of 1500 µm, and the Co ferrite film had a thickness of 2000 µm.

Furthermore, as a result of analyzing the compositions of the Mn-Zn ferrite film and Co ferrite film using an electron beam microanalyzer (EPMA), it was found that Mn/Zn/F e
= 7/3/20, Co/Fe = 1/19.

Next, the magnetic properties of the Mn-Zn ferrite film 8 and the Co ferrite film 9 will be examined using a vibrating sample magnetometer (VS
Measurement was carried out using M). As a result, the Mn-Zn ferrite film has Hc = 450e, M5 = 325esu/
cc, Co ferrite film Hc±=1.0K Oe
It was finished with SM s =260e*u/cc.

From these facts, the reason why the fixed magnetic disk of this example exhibits a higher reproduction output value than the conventional Co-Ni/Cr alloy 11111 magnetic disk at the high recording density side in the short wavelength range is that it does not contain the perpendicular magnetic recording component. Moreover, the reason why it exhibits a higher reproduction output than a Co ferrite thin film fixed magnetic disk is that a soft magnetic material is used as the underlayer, and a horseshoe-shaped magnetic path is formed with the Co ferrite magnetic layer. This is thought to be because the influence of the demagnetizing field is reduced.

Further, as another embodiment of the present invention, using the same film forming method, Ni-Zn ferrite, Mn ferrite, N
Co ferrite/Ni-Zn ferrite, Co
Ferrite/Mn ferrite, CO rough ferrite Ni ferrite or G.

A fixed magnetic disk with a two-layer film of ferrite/Zn ferrite was fabricated, and its electromagnetic conversion characteristics were evaluated.

As a result, Co ferrite/M n -Z of this example
Similar to the case of a fixed magnetic disk made of a two-layer film of n-ferrite, compared to a conventional Co-Ni/Cr alloy thin film fixed magnetic disk, the reproduction output shows a high value on the high recording density side in the short wavelength range. , the overall reproduction output was higher than that of a Co ferrite thin film fixed magnetic disk.

2, according to the above embodiment, M is placed on the disk substrate 7.
Since the n-Zn ferrite film 8 is formed and the cobalt ferrite film is further formed on top of the n-Zn ferrite film 8, a fixed magnetic disk with excellent reliability such as durability and hardness and capable of high-density magnetic recording is manufactured. be able to.

Effects of the Invention As is clear from the above embodiments, the present invention provides a base layer of Mn-Zn ferrite or Ni-Zn on a disk substrate.
The fixed magnetic disk has a structure in which a soft magnetic iron oxide film with a spinel-type crystal structure such as ferrite is formed, and a spinel-type iron oxide magnetic thin film containing cobalt with a columnar structure is formed as the magnetic layer, making it highly reliable. gender,
It is also capable of handling high recording densities, and since the plasma CVD method is used for its manufacturing method, two-layer films can be manufactured easily and continuously by simply controlling the supply of raw materials. This has the advantage that.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of essential parts of a fixed magnetic disk according to an embodiment of the present invention, FIG. 2 is a schematic front sectional view of a plasma CVD apparatus used to carry out the method for manufacturing the fixed magnetic disk, and FIG. The figure is a characteristic diagram comparing the relationship between the recording wavelength, recording density, and reproduction output of the fixed magnetic disks of the example and the conventional example, and Fig. 4 is an enlarged cross-sectional view of the main parts of the conventional fixed magnetic disk. be. 7...Disc substrate, 8...Mn-Z
n-ferrite film (iron oxide soft magnetic thin film), 9...
CO ferrite film (iron oxide magnetic thin film with spinel crystal structure containing cobalt). Name of agent: Patent attorney Akira Okaji and 2 others 7- Multi-isk work 9-- Go ferrite pus (Decoration 1 and correction of SL spinel type cotton crystal on cobalt) Figure 11 C--o - Submissive Cap Sipherite 11 Tsuyoshi ■ 8 Joseki 1 Ki Taster RL! ! Seiyasu (μm) Tadashii! Company! i' /l (KFRPI) Figure 14

Claims (5)

[Claims] (1) A fixed magnetic disk in which an iron oxide soft magnetic thin film with a spinel-type crystal structure is formed on a disk substrate, and an iron oxide magnetic thin film with a spinel-type crystal structure containing cobalt is formed on the iron oxide soft magnetic thin film. (2) 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 among zinc, manganese, and nickel. (3) The fixed magnetic disk according to claim (1), wherein the iron oxide magnetic thin film containing cobalt and having a spinel crystal structure has a columnar structure in a direction perpendicular to the surface of the disk substrate. (4) A mixed gas of the vapor of at least one of the organometallic compounds containing zinc, the organometallic compound containing manganese, and the organometallic compound containing nickel, the vapor of the organometallic compound containing iron, and oxygen. is reacted using plasma to form a soft magnetic iron oxide film with a spinel-type crystal structure on the disk substrate, and a mixed gas of the vapor of an organometallic compound containing iron, the vapor of an organometallic compound containing cobalt, and oxygen. A method for manufacturing a fixed magnetic disk, in which an iron oxide magnetic thin film having a spinel type crystal structure containing cobalt is chemically vapor deposited on the iron oxide magnetic thin film having a spinel type crystal structure by reacting the above using plasma. (5) Claim (4) wherein the organometallic compound containing zinc, the organometallic compound containing manganese, the organometallic compound containing nickel, the organometallic compound containing iron, and the organometallic compound containing cobalt are β-diketone metal complexes.
) The method for manufacturing a fixed magnetic disk described in .