JPH04182918A - Fixed magnetic disk and its production - Google Patents

Abstract

PURPOSE:To obtain high reliability and to facilitate countermeasure for high recording density by forming an oxide thin film which is amorphous in terms of X-ray as a substrate layer on a disk substrate and forming a spinel iron oxide magnetic thin film which has columnar structure and contains Co as a magnetic layer. CONSTITUTION:This disk is a fixed magnetic disk having three-layer structure where the oxide thin film 8 which is amorphous in terms of X-ray is formed on the disk substrate 7 and the iron oxide magnetic thin film 9 having spinel crystal structure which has the columnar structure in a direction vertical to the surface of the disk substrate 7 and contains cobalt is formed on the thin film 8. This fixed magnetic disk is produced by utilizing the activity of plasma and CVD reaction. Since the thin film 8 which is amorphous in terms of X-ray is formed on the disk substrate 7, the distribution of column diameter is reduced and the squareness of the fixed magnetic disk is improved, then the disk is excellent in reliability in durability and hardness and the high-density magnetic recording is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fixed magnetic disk that is highly reliable and 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 N
It has a five-layer structure of aluminum substrate and aluminum substrate, and has the drawback that the manufacturing process is complicated.

Figure 4 shows a conventional fixed magnetic disk C0-N i
/ This shows a cross section of a thin-film type fixed magnetic disk made of Cr alloy. Layer 6 is a lubricating layer.

Since the Co--Ni magnetic layer 4 of the above-mentioned conventional fixed magnetic disk is a longitudinal 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, 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 contact with each other, research has been actively conducted on Co--Cr1 film media. 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. There is a problem in that a protective layer 5 such as a carbon film or CO oxide must be provided.

On the other hand, in fixed magnetic disk drives, it is important to reduce the running height (flying hide) of the magnetic head relative to the magnetic disk as much as possible in order to reduce the output loss (spacing loss) caused by the magnetic head and magnetic disk spacing. This leads to improved density, and recently, in order to enable high recording density, 0.05 to 0.1
It is necessary to run with a flying hide amount on the order of μm.

However, both the conventional Co-Ni/Cr alloy thin-film recording medium and the Co-Cr thin-film recording medium have problems with durability, so a protective layer is added to the surface of the thin-film medium to ensure reliability. 5 (several 100 people), and therefore the problem remains that the spacing loss increases.

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 objects, the present invention forms an X-ray amorphous oxide thin film on a disk substrate, and forms an amorphous oxide thin film on the oxide thin film in a direction perpendicular to the disk substrate surface. A fixed magnetic disk having a three-layer structure in which an iron oxide magnetic thin film with a spinel-type crystal structure containing cobalt having a columnar structure is formed, and the fixed magnetic disk is manufactured by a manufacturing method that utilizes plasma activation and CVD reaction. It is something.

Therefore, according to the present invention, by forming an X-ray amorphous oxide thin film on the disk substrate, the distribution of column diameters is reduced, and as a result, the squareness of the fixed magnetic disk is improved and its durability is improved. It has excellent reliability in terms of strength and hardness, and is capable of 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 CoZnFe oxide film layer, 9 is a CO ferrite film,
lO 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, 12 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 is an exhaust system to maintain
6.17 is the vaporizer containing the raw material, 18.19.20 is the first valve for controlling whether or not carrier gas is introduced into the vaporizer, and 21.22.23 is the raw material gas and carrier gas. 24 is a carrier gas cylinder (nitrogen);
, 25 is a reactant gas cylinder (oxygen), and 26 is a substrate heating heater equipped with a substrate rotation mechanism.

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

Iron acetylacetonate (Fe (c
s H70□), ], Zinc acetylacetonate (Zn
(C5Hv Oz )z ・HtO), :2 pard acetylacetonate (Co (cs H,0□)3) was used, and dehydrated zinc acetylacetonate (in air at 100 2 hours), vaporizer 16
Cobalt acetylacetonate and iron acetylacetonate were placed in vaporizer 17 and heated to 80°C and 1130″ respectively.
Heat to C1120″C and hold. First valve 1
8 to 20 and second valves 21 to 23 are opened to supply nitrogen carrier (flow rate 1010 to vaporizer 15, 16, and 17, respectively).
5CC, the vapors of acetylacetonate of zinc, cobalt, and iron, respectively, and oxygen (flow rate: 53 CCM) were introduced into the reaction chamber 11, which was depressurized by the exhaust system 13, to generate plasma (power: 1.5 W/d). ,2
The reaction was carried out under reduced pressure (0.08 Torr) for 400
Disk substrate 7 (1
20 rotations/min), a CoZnFe oxide film 8 is formed on the
The first valve 18 and the second valve 21 were closed.

Further, under the same film formation conditions for 9 minutes under reduced pressure (0,
06 Torr) to form a CoZnFe oxide film 8
A Co ferrite film 9 is formed on top of the Co ferrite film 9,
A two-layer film of oZnFe oxide was formed. Then, the disk substrate 7 on which the second layer film was formed is placed in the reaction chamber 11.
A two-layer film with the same structure was formed on the back side using the same method, and a Co ferrite/ferrite film with magnetic thin film surfaces on both sides was formed.
A CoZnFe oxide disk was prepared, and then this disk was heat-treated in air at 300°C for 3 hours, and then submerged in a liquid bath (not shown) containing a fluorine-based organic lubricant. A fixed magnetic disk was fabricated by applying a lubricating layer 10.

The fixed magnetic disk of this example obtained in this manner was manufactured at 50 mA using a MIG head with a gap length CGL,') of 0.25 μm and a track width (Tw) of 10 μm.
The head current value was selected to evaluate the electromagnetic conversion characteristics.

A fixed magnetic disk was rotated at a speed of 360 Or, p, -, and evaluation was performed on a circumferential track of 20.0 square meters 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
00emu/cc Cr layer 3 and Co-Ni magnetic layer 4
The thickness of the magnetic layer consisting of is 800 mm, and a protective layer 5
A conventional Co-Ni/Cr alloy thin film type fixed magnetic disk (aluminum substrate with magnetization oriented in the in-plane direction) on which a carbon film was formed by 600 people and a lubricant layer 6 similar to the present invention was provided; A CO ferrite thin film fixed magnetic disk with a structure in which a CO ferrite magnetic film (preparation conditions are the same as for the two-layer film) was formed directly on a glass disk substrate was prepared, and electromagnetic conversion was performed under the same conditions as the fixed magnetic disk of this example. Characteristics were measured.

The relationship between recording density or recording wavelength and reproduction output was compared between the fixed magnetic disk of this example obtained in this way, a conventional fixed magnetic disk with a Co Ni/Cr alloy thin film, and a fixed magnetic disk with a CO ferrite FjJ film. The third
As shown in the figure. '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, (b) is a conventional Co-Ni/Cr alloy thin film fixed magnetic disk for comparison, and (C) is another conventional Co ferrite thin film fixed magnetic disk. The characteristics of the fixed magnetic disk (Co ferrite single layer film) are shown.

From FIG. 3, it can be seen that the fixed magnetic disk of this embodiment is different from the conventional Co-
The reproduction magnetism shows a higher value on the high recording density side in the short wavelength range than the Ni/Cr alloy thin film fixed magnetic disk or the Co ferrite thin film fixed magnetic disk, and the fixed magnetic disk of this example can support high recording density. is clear.

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 M1 conversion characteristics, the lubricating layer 10 of the fixed magnetic disk of this example was removed using an organic solvent.
The crystal structure of the o-ferrite film 9 was analyzed by X-ray diffraction.

As a result, it was found that the CO ferrite layer 9 had a spinel type crystal structure and was preferentially oriented in (100).

For comparison, a sample was prepared in which only the CoZnFe oxide film 8 was formed on a glass disk substrate under the same film forming conditions as in the above example, and after heat treatment in air at 300"C for 3 hours, As a result of analyzing the crystal structure by line diffraction, it was found that the CoZnFe oxide film 8 was amorphous in terms of X-rays.

Furthermore, the fixed disk of this example and the conventional Co ferrite thin film fixed magnetic disk (single layer film) were broken and their surfaces and fractured surfaces were observed using a high-resolution scanning electron microscope. 2 fixed magnetic disks
The layer film has a columnar structure, and the film thickness is approximately 3100 mm, and the column diameter is 450 to 550 mm. It was found that there were about 2,500 people and the column diameter was 200-700 people.

Next, the magnetic properties of the Co ferrite film 9, the CoZnFe oxide film 8, and the Co ferrite/CoZnFe oxide fixed magnetic disk were measured using a vibrating sample magnetometer (VSM). As a result, CoZnFe oxide film 8
showed no magnetism, but Co ferrite)/CoZnF
e-oxide fixed magnetic disk is CO ferrite! ! 9
It showed superior squareness compared to . Also, Co ferrite/C.

The coercive force of the ZnFe oxide fixed magnetic disk is Hc±=1
2000 e, Hc/=7800 e, and Ms was 284 emu/cc.

From these facts, the reason why the fixed magnetic disk of this embodiment exhibits a higher reproduction output value than the conventional Co ferrite thin film fixed magnetic disk at the high recording density side in the short wavelength range is because the amorphous C is used as the base film.

This is thought to be due to the fact that by using the ZnFe oxide film 8, the distribution of column diameters became smaller than in the case of a single Co ferrite layer, and as a result, the squareness of the Co ferrite/Co Z n Fe oxide fixed magnetic disk was improved. .

In addition, as a result of conducting similar studies on other elements shown in claim (2) as the amorphous oxide yiwX in terms of xVA, the same effects as in the case of the CoZnFe oxide film 8 were obtained.

In this way, according to the above embodiment, since the amorphous CoZnFe oxide film 8 is formed on the disk substrate 7 and the Co ferrite film 9 is formed thereon, reliability such as durability and hardness is improved. It is possible to manufacture a fixed magnetic disk that is excellent and capable of high-density magnetic recording.

Effects of the Invention As is clear from the above embodiments, the present invention forms an X-ray amorphous oxide thin film as an underlayer on a disk substrate, and further forms a spinel iron oxide film containing Co having a columnar structure as a magnetic layer. Because it has a fixed magnetic disk structure with a magnetic thin film formed on it, it is highly reliable and can support high recording densities.Also, since the manufacturing method uses plasma CVD, it is easy to use. This method has the advantage that a two-layer film can be manufactured easily and continuously by simply controlling the supply of raw materials.

[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 and showing the relationship between recording density or recording wavelength and reproduction output of the fixed magnetic disks of the embodiment and the conventional example, and FIG. 4 is an enlarged sectional view of the main part of the conventional fixed magnetic disk. 7...Disc substrate, 8...CoZn
Fe oxide film (amorphous oxide thin film), 9...
...CO ferrite film (iron oxide magnetic thin film with spinel crystal structure containing cobalt). 7-m-tice ri kari ni & j 5-island structure cocooned iron mahjong sex 1 cape san no 1 Figure (C) ÷ keyaki's COO 12 lights! Ura Kozu eyebrows “Exposed Teisk 2 Density 1t (*FspO

Claims (4)

[Claims] (1) Iron oxide magnetism with a spinel-type crystal structure containing cobalt, which is formed by forming an amorphous oxide thin film on the disk substrate in the direction of X-rays and having a columnar structure perpendicular to the disk substrate surface on the oxide thin film. A fixed magnetic disk with a thin film formed on it. (2) The X-ray amorphous oxide thin film contains at least one element from the 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, comprising: (3) Organometallic compounds containing magnesium, organometallic compounds containing calcium, organometallic compounds containing titanium,
Organometallic compounds containing vanadium, organometallic compounds containing manganese, organometallic compounds containing iron, organometallic compounds containing cobalt, organometallic compounds containing nickel, organometallic compounds containing copper, organometallic compounds containing zinc, strontium , an organometallic compound containing niobium, an organometallic compound containing cadmium, an organometallic compound containing barium, and a mixed gas of oxygen and a vapor of at least one organometallic compound, reacting using plasma, An amorphous oxide thin film is chemically vapor deposited on the disk substrate by X-rays, and a mixed gas of oxygen and organic metal compound vapor containing iron and cobalt is reacted using plasma. A method for manufacturing a fixed magnetic disk, comprising chemical vapor deposition of an iron oxide magnetic thin film having a spinel crystal structure containing cobalt on the oxide thin film. (4) Organometallic compounds containing magnesium, organometallic compounds containing calcium, organometallic compounds containing titanium,
Organometallic compounds containing vanadium, organometallic compounds containing manganese, organometallic compounds containing iron, organometallic compounds containing cobalt, organometallic compounds containing nickel, organometallic compounds containing copper, organometallic compounds containing zinc, strontium Organometallic compounds containing , organometallic compounds containing niobium, and organometallic compounds containing cadmium are
- The method for producing a fixed magnetic disk according to claim 3, wherein the diketone metal complex is used.