JPS62192913A - Vertical magnetic recording medium and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [J! 1' Work 1. Field of Application] The present invention relates to a magnetic recording medium, particularly a magnetic recording medium using superimposed magnetization.
The present invention relates to a polished recording medium for forming a surface layer suitable for surface layer processing, a method for forming the surface layer, and a method for forming the surface layer.

[Prior art 1] Compared to the current in-plane magnetic recording force type, the I magnetic recording force type has the ability to drastically reduce the recording density by 1° in the direction of From IJ? Nitto-C is extremely Φ yellow. As a recording medium for eastward magnetic recording, C
o and [Go alloys represented by the Shiro-01 alloy, or Ha), and Lii have been developed.

Ba--No, -Write medium is 13a--
Noelite W1. This method involves dispersing the material r and applying it to the substrate 1, which has the advantage of being able to use conventional recording medium manufacturing methods, but has the disadvantage that the saturation magnetic flux density Bs is small.

Co or Co formed in a vacuum, by sputtering, by thin film deposition
The 1F direct magnetization film made of o alloy is Bs or Ra-) and 11. Bedejinkiku, that's why Sarabanko high density 1 negative record is 11
1 ability. However, although Co or Co alloy 11 has excellent magnetic properties, its large If-friction coefficient and inferior 1IljHI wear+1 have traditionally been obstacles to its practical use.

That is, it can be seen that the magnetic recording medium slides with the spatula F at a high speed, and the contact with the disk is extremely good. For example, in the case of an 8mlIll-' thioformed VTR, the relative sliding speed between the hend and the videotape is 3.75 m/see. In addition, the highest recording wavelength in the same former is approximately 0.7 μm, so in order to suppress the top spacing loss to 1 dB or less, the head and tape must not contact each other at a distance of 150 A or less. Must not be. The closer the contact is, the stronger the shearing force is and the greater the wear. Not limited to video applications,
In magnetic recording systems such as the external memory of RIIL computers, audio tapes, and flexible disks, higher recording densities improve the contact between the head media and increase the relative sliding speed (f). Abrasion resistance of magnetic recording media is a key point in practical use.

In particular, metal film media pose a serious problem because they cannot be mixed with a lubricant in the binder, which is the case with conventional coated media.

In order to improve wear resistance as described below, magnetic metal thin films are usually subjected to surface treatment. A large number of surface treatment methods have been proposed so far, including modified methods7).
, the force υ that allows organic compounds such as metal soap and fatty acid ester perchloropolyether to adhere to the magnetic +1 layer has been evaluated, but protective lubricants that provide 1' durability +1 are Not yet.

In addition, many studies have been conducted on the inorganic Hoichiki layer, such as JP-A-50-1041302, JP-A-54-
No. 14712, Japanese Unexamined Patent Publication No. 80, No.-57533', ~゛,
Y method for protecting seedlings on the magnetic +1 layer surface with metal oxides, 1~
Opening II/(No. 54-141107, Japanese Unexamined Patent Publication No. 51-338
It is known that the surface of the magnetic material is coated with a wear-resistant alloy such as 04d, but it has not yet been technically completed.-1
One of the metal oxide protective layers described in , is a series of f-'/) in which the surface of the film is coated with an oxide of cobalt alloy≠cobalt. This technical idea has already been disclosed in Japanese Patent Publication No. 42-20025d, 1986, and according to it, plated GOI+! ,! Or CoP, CoNi, C
A thin alloy film such as oN1P is subjected to surface oxidation in five types of meltening + 1 atmospheres: a constant humidity bath, a constant temperature bath, a constant temperature bath containing steam, or a constant temperature and humidity bath containing pure oxygen gas, and the surface is coated with Co304. It is said that this oxide has improved the wear resistance and corrosion resistance of the media. In addition, Japanese Patent Application Laid-Open No. 58-41438 describes surface treatment of metal film media manufactured by so-called physical vapor deposition processes such as vapor deposition, sputtering, and ion blasting, using a relatively recent vacuum process. The law has been disclosed.According to the same publication,
When directing a vapor flow of a substance containing cobalt onto a substrate of a molded product in a vacuum chamber to form a ferromagnetic layer on the substrate, the vapor flow is applied to the ferromagnetic layer to form a surface portion. By directing oxygen-containing gas to the exposed areas, a layer of mixture of G O and Co304 is formed on the surface, improving environmental stability and wear resistance. The effectiveness of this type of method has been recognized as CoNi alloy-based in-plane magnetized media have been deeply studied in recent years, and the same content has been disclosed in JP-A-60-1914251, for example. It will be done.

However, as described above, the method of oxidizing the final stage of magnetic film formation, that is, the surface forming part of the magnetic film, was developed as a method for manufacturing a longitudinal recording medium using a typical Co old gold alloy. The following problems have been identified as a method for improving the wear resistance of perpendicular magnetic recording media.

First, since oxygen also diffuses into the vapor flow forming the inside of the magnetic film, there is a limit to the supply of oxygen, and the surface layer cannot be strongly oxidized. In fact, there have been no reports that if the oxygen pressure is increased too much, the wear resistance is improved, but the electromagnetic performance measured by the C/N ratio etc. is significantly deteriorated (8th Japan Society of Applied Magnetics, Academic Lecture summary collection °84
゜P, 28B). In particular, Co mainly in CoCr alloys
Since the O perpendicular magnetic recording medium has an alloy composition with a low Bs in order to generate perpendicular magnetic anisotropy, a further decrease in Bs due to mellowing during the surface formation process will cause a severe deterioration in the medium performance. For example, the CoCr alloy currently being considered as a perpendicular magnetization film has a composition of around 20wt% Cr, and the Bs at this time is about 4000G (IE
EE Trans, MAG-17, No. 8. P
, 3172).

The second problem is that it is not possible to form an optimal thin film on the surface layer. When forming the magnetic film that will be used for recording, it is desirable to use a vacuum evaporation method in consideration of acidity, but since the surface oxidation layer is very thin compared to the recording layer, the specific gravity of the film formation rate is low and wear resistance is low. , other methods can be used to maximize corrosion resistance. Generally, thin films formed by vacuum evaporation have a low packing density and weak adhesion to the substrate, so they are prone to wear, fall off, etc., and are also prone to corrosion.

Third, the material composition inside the magnetic layer and the surface layer cannot be changed, making it impossible to optimally design the film.

Due to these problems, the known technique of forming an oxide protective film mainly composed of Co on the surface of a Co-based double perpendicular magnetization film, as in Japanese Patent Application Laid-open No. 8O-50Ei22, is based on the method of forming a new magnetic layer on an already formed magnetic layer. Forms oxides and becomes blue, or
A method such as post-processing the already formed magnetic layer in an oxidizing gas atmosphere F is adopted as in No. 143538. However, C on the perpendicular magnetization film formed by these methods
As a result of studies by the inventors, it has been found that the o-based oxidation-resistant film has the following problems and requires improvement in practical use.

The most serious problem is that it has poor adhesion to the substrate and is easily peeled off, so the effect of improving wear resistance is not sufficient. The reason for this is that the formation process of the oxide protective film is not continuous with the formation of the magnetic film, so the bonding at the atomic level at the interface between the two films is poor, and the crystal phases of the oxide film and the magnetic film are different.
This seems to be due to the fact that epitaxial growth is difficult due to lack of lattice matching. The GOO compound crystal phase that is effective in improving wear resistance is GO304 spinel, while the CoCr alloy has a hexagonal crystal structure. Also, the CoC phase that is said to be intermediately produced by oxidation is NaCl! ice of the structure, and its a-axis lattice definition is 4.21338A, (111
) plane's nearest neighbor Co-Co distance is 3.015 A. These are CoCr alloy a = 2.52A (Th
in 5olid Films, +01 (“83)
8l-73), which is completely incorrect.

The second defect mentioned is that the performance of the CoO film obtained by reactive sputtering or reactive vapor deposition using 02 gas is extremely poor in reproducibility, and does not rust as a result of rapid production. This is because the thin nature of the oxide that is formed sensitively reflects the oxygen atmosphere of the deposition system, and the getter action that occurs on the substrate, members around the target, the vacuum chamber wall, etc., and the state of the gas re-release process. The oxidation reaction changes from moment to moment.

[Problems to be Solved by the Invention] The present invention is directed to 1-I
'+12 magnetic recording media are provided. The present invention
Heat]7〈Abrasion resistance +1. To provide a modified overlapping magnetic recording medium of Chukyu P1. The present invention is.

By applying it to magnetic tape, it can run bravely (+especially 1
We provide refurbished magnetic tapes. Moreover, 1 of the present invention
-1 objective is to provide a Co-based alloy orthogonal magnetic recording medium structure I&〃 with excellent corrosion resistance P1.Furthermore,
An object of the present invention is to provide a method for manufacturing a novel magnetic recording medium that has the characteristics described in item 1-7-j and is easy for a manufacturer. By using the manufacturing power of the present invention, it is possible to obtain a surprising improvement in performance of the medium and improvement in manufacturing yield by only adding improvements in J' and l- to the conventionally known manufacturing method. I can do it.

Means and effects for solving the problem 1 The present invention includes:
1T with at least Co as a component in the non-magnetic +1 substrate 1-
ill I! In a magnetic recording medium laminated in the order of 1 to 11, I magnetization 11 and [:0 as one component are 119k and 1 to 1.
) to J1 direction, also contains A (;- slope is IIL, 1) Oxygen-containing l1ii on the outermost surface side of the body of the oxidation cavity is 1- Co
By constructing a magnetic recording medium, the object of Section I can be achieved so that the oxygen content on the side of the interface between the 1-component and the 1-component is greater than 1. , and as - its production X - force V.

11f flexible J1 magnetic + 1), (form a perpendicular magnetization film with at least Co as one component on body 1 by physical vapor deposition process No. 2, and further, I
l kM-shaped ton l! 'I Manufacture of magnetic recording body 11
5 〃, and i of the part where the oxide film is formed 6
To provide a manufacturing capability V of a small lI'I magnetic recording medium characterized in that the force surface on which the oxygen scum near l1 is L is in the direction opposite to the direction of the magnetic film formed in the direction of the river (body A4). It is something.

FIG. 1 shows a small cross-sectional view of a magnetic recording medium manufactured according to the present invention. 11 is usually a base film with the right machine part as part 1-1, 12 is a metal thin mold l ['
I magnetic recording layer, made of Co, Co-Cr.

Co-V, Co-No, Co-1 and Co-Cr
-Pd, Co-Cr-No.

There are co-Cr-Rh shades, among which Co-Cr has a large perpendicular magnetic anisotropy of +1, and a perpendicularly magnetized film can be obtained relatively easily. Therefore, as the magnetic recording layer 12, Co-O
r is preferred.

The magnetic recording layer 12 may be formed facing the substrate +11:', or may be formed with an intervening intermediate layer of a metal film such as Ti, Bi, Ge, or an amorphous film. Also,
A high permeability magnetic layer may be provided between the base 11 and the magnetic recording layer 12 or between the base 11 and the intermediate layer for the purpose of increasing recording efficiency and reproduction output.

The base 11 is made of polyester, polyimide, polyamide,
In addition to compounds such as polyacetate-1 and polysulfone, inorganic materials such as glass, aluminum, and surface-hardened aluminum are also available.

13 is a CoL component oxide film which is the main point of the present invention. The effect of the C0-main component oxide film according to the present invention is based on the following principle. As disclosed in the aforementioned Japanese Patent Publication No. 42-20025, Mori, and Japanese Patent Publication No. 54-21555, etc., a Co oxide film having a spinel structure co304 has solid-liquid lubricating properties, and It is a material with high hardness and excellent medium protection +1. It is also a chemically stable material, and its surface properties can be maintained even in harsh environments such as high temperature and high humidity.

However, in order to exhibit such a function, it must be strongly bonded to the underlying magnetic layer. The sliding conditions between the magnetic recording medium and the magnetic head are extremely severe.
If only a spinel oxide crystal layer of C03D4 is formed on the surface inside, the bonding force between the magnetic layer and the layer is weak, so sliding cannot be achieved and the surface layer peels off. As a result, it is not possible to maintain properties such as itching resistance and corrosion resistance. Therefore, an intermediate layer that couples the Co304 oxide layer with the magnetic layer at t° in a strong [-11 manner] is effective, and providing this intermediate layer is the gist of the present invention. Due to the presence of the intermediate layer, it is possible to firmly bond the Co-based perpendicularly magnetized film with the different hcp structure and the oxide structure formed on the surface because of the crystal phases.

It was confirmed that the intermediate layer 1- can be achieved by providing an unsaturated oxide layer having a lower degree of oxidation than the outermost oxide layer. The reason for this is inferred as follows. Co
-1-; As the amount of oxygen contained in the alloy increases, the phase changes in the order of crystalline metal, microcrystalline metal, amorphous metal, and spinel Co3O4. Therefore, the crystallographic inconsistency between the spinel structure on the outermost surface and the underlying Co-based magnetic recording layer hcp structure is caused by unsaturated oxides such as microcrystalline metals with extremely fine crystal grains or amorphous metals. It is possible to form a film of the wear-resistant material GO304 on the medium-1- while maintaining the atomic bond.

1- The reason why the intermediate layer can absorb crystallographic inconsistency is that neither microcrystalline metals nor amorphous metals have long-range atomic arrangement order.

The term "amorphous metal" as used herein means an amorphous metal based on X-ray diffraction.

It refers to a material phase in which no unique peak reflecting any structure is observed in crystal analysis methods such as line diffraction, making it difficult to identify the internal crystal structure, and which exhibits a metallic appearance based on electrical conductivity, appearance, etc. . Such a state is said to occur not only in a so-called glass-like amorphous state but also in aggregates of microcrystals with extremely small grain sizes. Generally, the lattice is disordered in the vicinity of grain boundaries. Therefore, if each microcrystalline grain is very small, there will be no part with an internal regular arrangement, and no peaks as seen in diffraction will appear.

According to the inventors' studies, in addition to the above-mentioned amorphous layer, microcrystalline metal layer, or a mixed layer thereof, effective intermediate layers include a mixed state of oxide crystal and cobalt metal that functions similarly. . This is because, in this case as well, the oxide crystals and metal crystals are mixed randomly, resulting in a lack of long-range order. It is difficult to uniquely determine the type of crystallographic content of the intermediate layer that will appear depending on the formation striations of the film.

In any case, by providing such an intermediate layer of unsaturated oxide with no long-range order, the uppermost surface spinel crystal layer with a stoichiometric composition and the underlying HCP structure consisting of a pure metal composition and a co-based vertical The lattice alignment of the magnetized film can be absorbed, and the oxide film protective layer and the magnetic layer are strongly coupled.

In addition, it is desirable that the magnetic layer and the oxide film have similar metal components.
It is desirable to be covered with an oxide film of the main component. Therefore, in the case of the Co-based perpendicularly magnetized film of the present invention, its outermost surface has a basic structure in which cobaltite Co3O4 or some Caff1 atoms thereof are replaced with other additive atoms. The underlying layer is an unsaturated oxide layer with no long-range order, typically a mixture of amorphous metals, microcrystalline metals, or both, or cobaltite 1-Co304. It is a mixture with crystals.

In order to obtain the above-mentioned oxide film structure, for example, when forming a Co oxide film by reactive sputtering, reactive vapor deposition, etc., as described in the examples below, oxygen gas is supplied in the opposite direction to the substrate running direction. There is a way to flush it out. By adopting this method, C
Problems in forming an o# film are solved.

Alternatively, when surface oxidation is performed by RF glow discharge or oxygen ion implantation in an oxygen atmosphere, similar effects can be obtained by appropriately selecting the ion kinetic energy distribution, plasma exposure time, etc. According to the inventors' studies, it has been found that the f method, in which a new oxide film is formed, tends to be easier to control the stacking of oxide crystal phases.

[Example] The effects of the present invention will be explained below based on examples.

Example 1 A CoOr magnetic layer having a thickness of approximately 0.3 gm was formed on a PET film having a thickness of approximately 35 μm using an RF sputtering device (not shown) using a CoCr alloy target. Next, the film after the magnetic layer was formed was set on the rolls 2+i of a sputtering apparatus shown in FIG. 2, and the Co oxide film of the present invention was formed into a shape 1.

In FIG. 2, the film 23 unwound from the unwinding roll 21 passes through the free roller 22, rotates along the outer periphery of the can 24, passes through the free roller 25, and passes through the take-up roll 26. It is wound up.

The formation is Co pure metal target 33 true 1. mask 2
This is done by RT which passes through 7 and 11 sections. 34
．． Reference numerals 35 denote introduction tubes for introducing waste, and in this embodiment, 02 is introduced from the tube 34, and Ar is introduced from the tube 35. The pipe 34 forms a C degree II4 of the introduced gas at the 11th rising part, that is, the gas concentration is higher closer to the gas outlet 11 of the pipe 34. For this reason, in the apparatus shown in FIG. 2, in which the substrate after forming the magnetic PI layer moves against the flow force surface of the 02 gas, in the initial stage of oxide film formation, the atmosphere is low in oxygen.
Further, in the final stage, an oxide film is formed in an atmosphere with a large amount of oxygen. Note that the concentration of Ar gas introduced from the pipe 35 is +1
It is almost constant near the Q part.

The device used was a magnetron-spantalin hook type, and the nu5pe...tarinku article I was 11i, heel vacuum 7ii3Ei, and AI! I tai1lIcArmonth0.
5pa.

0;・minute month 0.05pa, sputtering (7)
To ML Xi1. , , -, -1- is 3000A/mi
There are nte. II and J of the surface layer were controlled by changing the A-line speed of the I-p. The 11th part of the anti-foil root is approximately B.
Om + n length 1 ~ 41, hoop run t1 speed melon IJ2
m/win. Ji/mi of the Co oxide film that was not formed is approximately +oo A.

Identification of the oxide film structure in this example was carried out using optical spectroscopy.
2, ESCA and electric r-ray diffraction. I became. While the surface was Ar-etched, the irradiation of the film was carried out using 11111 A-electron Y spectroscopy.
jiL 411 constant f; is shown in FIG. 3(a). In the figure, the horizontal axis shows the phase 111 between the etching layers 115 and 111 at the depth from the outermost surface, and the curve 38 shows a decreased Cr concentration. vinegar. As shown in oxygen concentration curve 37, what is the oxygen concentration that is obvious in terms of thickness during Co oxidation? There is a shoulder, the middle number from the top surface, 'Oxygen concentration fat decreases] 7.

It can be seen that a small saturated oxide is formed on the side near the interface with the CoOr magnetic layer, and the oxygen concentration is continuous with that of the CaCr layer. For your reference, Section 3l-A(b
), the oxygen partial pressure measured in the ionization vacuum 5136 is 0.0.
2pa, 0. The Auger analysis values of each oxide film formed with a film formation rate of 12 pa are shown by curves 39.40.

This sample with a partial pressure of 0.12 pa is from Comparative Example 2, which will be described later. At 0.12 pa, the oxide film has a very uniform oxygen concentration. It can be seen that at a partial pressure of 0.02 pa, most of the oxide film is metal, and only the outermost surface is oxidized. It is assumed that this outermost oxidized layer was formed in the atmosphere rather than in nature.

ESGA also obtained elemental concentration measurements almost similar to those in Note L, and furthermore, knowledge regarding the stacked state of crystal phases was obtained. E
Analysis of the crystalline phase by SGA shows that Co30n spinel contains divalent and trivalent Co ions, whereas the amorphous phase contains only divalent ions.
According to the inventors' study, as a result of ESCA analysis of the sample of this example without etching, the thickness of the layer containing trivalent cobal I was approximately 50A, 2
It was found that the layer containing only Co ions below the valence of GOA is stacked on one of the layers containing C (-ki).Therefore, there is a layer of Ca:+Oa of 50A, and the unsaturated oxide below it. Since the layer does not contain trivalent ions, in this case r
It can be concluded that the layer is composed of 11% GO30, contains no compound crystals, and is composed of an amorphous metal, a microcrystalline metal, or both.

The oxide film of this example was also analyzed by reflection type and transmission type electric f-ray diffraction. In the reflection electron beam diffraction, the electron beam diffraction shown in Table 1m was performed while the surface was Arr-etched. It is possible to analyze the structure of about 2OA of the outermost surface based on the penetration depth of electrons. It is clear that Ga2 is present in the sample before etching.
A peak of O3 spinel is observed, and the outermost surface of this example is identified as spinel. When etching progresses to about 35A, no peaks are observed at all, resulting in a phase with no long-range order. However, since Ar etching destroys the surface order to some extent, it is difficult to read the difference between the amorphous phase and the microcrystalline phase from this analysis. Etching progressed further, and peeling of hcp Co appeared when 100A of the oxidized layer was removed. However, this peak is broad due to surface destruction. - The sample for force transmission electron beam diffraction was prepared by slicing the cross section of the sample of this example to a thickness of approximately 5 (+OA) using a microtome, and scanning the focused electron beam from the outermost surface of the slit cross section. The crystal phase is identified by looking at the diffraction line of the beam.As the electron beam scans, a fairly clear spinel phase is detected from the outermost surface, and the hcp of CoCr is detected through a region with no peaks other than the extremely weak hcp cobalt. (A signal indicating the structure was obtained.) (The analysis results of the layer structure supported the results of reflected electron f-ray diffraction described in 1-1, but it was difficult to identify the thickness of each layer due to the size of the spot diameter.) Both the spinel diffraction signal and the HCP structure diffraction signal showed gradual changes during scanning, and it was difficult to define the layer boundaries using current electron beam source technology.

1. The medium described above was punched out into a 5-inch diameter disk, and evaluated using a floppy disk driver.

Example 2 35 JLm thick PET film similar to Example 1-1-
This is a 5-inch floppy disk on which a CoCr layer with a thickness of 0.3 μm is formed, and the only difference from Example 1 is that the sputter target 1-33 during oxide film formation is a CogoMo2O alloy. The AES and ESCA results showed that almost the same oxygen concentration profile as in Example 1 was obtained in the oxide film thickness direction. Further, the results of reflected electron beam diffraction revealed that the outermost surface was a Co304 type spinel phase, and when etched by about 50A, it became a phase with almost no peaks.

Despite containing MO, Co304 on the outermost surface
The reason why it shows a structure not much different from that is interpreted to be because it is a solid solution phase in which divalent Co ions are replaced with MO ions, so No precipitation does not occur.

Furthermore, when a Co-based acetic acid film is formed by reactive sputtering as shown in Fig. 2, the antiferromagnetic C00 phase is difficult to develop regardless of the presence or absence of additives, and even if it is observed, it will be very small. , there is a tendency to change from an amorphous-like metal phase to a spinel phase, not only in this example.

Example 3 10) Approximately 0.4 p, m was deposited on a z+n thick polyimide film using an electron beam heating vacuum evaporation device (not shown).
A thick CoCr magnetic layer was deposited. Thereafter, the same treatment as in Example 1 was performed to form an oxide film. The results of the surface analysis obtained were also the same as in Example 1. The film of this example was cut to a width of 8 mm and evaluated using a home VTR.

Example 4 A CoCr magnetic layer having a thickness of approximately 0.4 μm was formed by vapor deposition on a 10 JLI1+ thick polyimide film, which was the same as in Example 3, using an electron beam heating vacuum evaporation device (not shown). Next, the film after the magnetic layer was formed was set on the unwinding roll 21 of the vacuum deposition apparatus shown in FIG. 4, and the GO oxide film of the present invention was formed.

In FIG. 4, the film 23 on which the metal thin film magnetic recording layer has already been formed is unwound from the unwinding roll 21, passes through the free roller 22, rotates along the outer periphery of the can 24, and passes through the free roller 25. The film is then wound onto a winding roll 26. On the other hand, the Kobal I vapor deposited material 28 housed in the crucible 28 is melted by the electron beam 30 emitted from the electron gun 3I. The steam flow introduces oxygen gas into the inlet 3
2, it passes through the opening of the adhesion prevention plate 27 and adheres to the metal thin film magnetic recording layer of the film 23, forming a chemically resistant thin film. An anti-adhesion plate is placed in this opening so that it is directly below the can.

Surface analysis of this example using AES and ESCA revealed that
It was found that the unsaturated oxide phase had a slightly higher oxygen concentration, accounting for 30% of the total number of atoms at the Coer interface.

In addition, the measured value of trivalent Co ions by ESCA shows that although the Cr concentration gradually decreases in the depth direction, it is observed up to a point where the Cr concentration reaches a significant value, forming an intermediate layer where metal-like phases and oxide crystals coexist. .

FIG. 5 shows the measured values, and curve 51 indicates trivalent Co ions.

A curve 52 shows the composition ratio of oxygen atoms, and a curve 53 shows the composition ratio of Cr atoms (including ions). The conclusion that - is also supported by reflected electron diffraction; the outermost surface is Co304 spinel, and the lower layer has a structure in which the Co3O4 peak gradually decreases, and no single peak of Ca was observed. At low oxygen partial pressures where GOO crystals appear, the outermost surface does not completely turn into spinel.
is. Of course, such manifestations are not essential to power, but can be seen to depend on the device. By forming an oxide film using a combination of an appropriate mask shape, film formation layer 1, and oxygen introduction system, it is possible for a single metal phase to coexist in the (micro)crystals of the Colt body at the interface between the outermost spinel and the interface. ■L is determined. The film of this example was cut into 8m+4v11 pieces and evaluated using a home VTR.

Example 5 In the same manner as in Example 1, a 5-inch diameter sloppy disk was manufactured with 35 JJ, m J'/PET 74 lum. The magnetic layer material is Co85V+h alloy, and the oxide film material is also Co8hV+
5 alloy. In this example, when the 02 partial pressure at the time of oxidation +1u formation was lowered to about 0.03 pa, the oxygen concentration of one ship tilted at the same τ as in Example 1? ! The LM layer and the CoV magnetic layer were continuous. At this time, the stacked state of the crystal phases was also approximately the same as in Example 1 and time t9.

Example 6 A heavy magnetized film of Co oxide was deposited at 0.35k by sputtering on fPET film 1- at 35lmJI.
It was formed to a thickness of 7 m. The force V required to spun a Co metal target I in an oxygen atmosphere with a force V smaller than t'+#/Changhua 1 model is known, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-2
1! It is sufficient to use a technique in which the opening is reduced to +025', 369. Using the device 7i shown in FIG. 2 for the first step, applying the same force as in Example 2, forming the Co oxide 119 of the present invention with the CoI alloy 22 alloy 1. Ta. In the surface analysis of this example, the outermost surface is spinel, the de layer is a 77 lunion gamma phase, and the microcrystalline metal u gold phase. I couldn't tell the difference between 1 degree and 1 degree.

Ichiriki This Example C was determined using the compositional analysis value of ESCA and Auger main 1 spectroscopy, with a depth of approximately 85.8 cm as a boundary.
A rapid change in rg was observed. Considering that the thickness of the spinel phase was about 50A in this example46 (then, in this example, the crystallographic structure of the 119F layer portion of the oxidized skin of the present invention and the oxide-based perpendicular magnetization film is almost continuous. It is concluded that

Comparative Example 1 Same as Example 1, 357tm J'/P
ET I.

A CoCr magnetic layer of type I&1. Also, a surface oxidation layer was formed using force. In other words, in Figure 2,
Close 34? A mixed gas of Ar gas and 02 gas was introduced from i.35, and a Co oxide film was formed at a 02 partial pressure of 0-08 pa. The oxygen concentration is uniform throughout the entire thickness of the resistive film, and based on the composition ratio and the results of reflection Tit f-ray diffraction, it is a Co304 phase. The profile of the element concentration in the film analyzed by ESCA is shown in FIG. Curve 61 represents oxygen, and curve 62 represents chromium.

Comparative Example 2 In Example 1, when the 02 partial pressure was set to 0.12 pa, a uniform spinel phase was obtained over the entire thickness (see FIG. 3 above). It was evaluated as a floppy disk.

Comparative Example 3 When the 07 partial pressure in Example 1 was set to 0.02 pa,
An oxide film was obtained in which only the outermost surface was liquefied and the interior was mostly metal (see Figure 3 above). It was evaluated as a Flo 2P disc.

Comparative Example 4 Same as Example 2, 35 g m f'J PET-1
: Coer sputtering film is formed on the surface of Co8.
The oMo2o alloy oxide film was made with an oxygen partial pressure of 0.1 as in Comparative Example 2.
It was formed at 2pa. The resulting 11% homogeneous spinel phase. It was evaluated as a floppy disk.

Comparative Example 5 Same as Example 1, 3 Jtm thick PET, eocr/a in 1
+1 layer was formed by sputtering. The surface oxidation layer was formed by sputtering using Co oxide Targetera I in the apparatus shown in Fig. 2, with the tube 34 closed and only the A gas introduced from the tube 35.l) The formed film was almost uniform. It was an amorphous film with about 20A of IA or saturated oxidation on the outermost surface.The oxidation on the outermost surface probably occurred when it was left in the atmosphere.It was evaluated as a floppy disk.

Comparative Example 6 As in Example 3, a CoGr magnetic layer was deposited on the 1101L thick polyimide film J1, and then a uniform spinel phase of pure GO was formed using the same method as in Comparative Example 1 using the apparatus shown in FIG. did. It was cut into 8 mm width and evaluated as a videotape.

Tables 1 and 2 were obtained by summarizing the results of experiments conducted to the north. The effects of the present invention are obvious.

Table 1 The main purpose of the oxide film of the present invention is to have an oxygen concentration gradient in the thickness direction, and when the oxygen concentration ratio between the outermost surface side and the magnetic layer side approaches each other as in Example 4, the durability increases. Performance begins to drop slightly. The degree of oxygen concentration gradient required cannot be determined unconditionally depending on the oxidation state of the surface of the magnetic layer and the presence or absence of oxide film additives, but the inventors' study found that It seems that sufficient performance is often not achieved unless there is a concentration difference of 1.5 times. If the outermost surface is composed only of Co304, the oxygen concentration of this phase is 57 at
omic'l, the oxygen concentration at the magnetic layer interface is 3.
8atomic! It is better to be less than or equal to More preferably, if the oxygen concentration difference is about 1.8 times or more, the oxide film will have extremely good performance.

The present invention can be applied to a wide range of oxide film thicknesses, but it is preferable that the thickness of the outermost spinel phase and the lower microcrystalline or amorphous phase be 30 to 100 OA. good.

If the film thickness is less than 30A, the mechanism for maintaining bonding strength will not function properly due to gradual changes in the crystal phase, and the effect of the protective layer will be weakened. Also, 100OA or more
-, the thickness of the nonmagnetic layer becomes thick, and the spacing loss during recording and reproduction becomes too large. Furthermore, a more preferable range of the oxide film thickness of the present invention is 50 to 300A.

[Effect of the invention 1 As described in -1- below, the present invention has a Co oxide film on the surface of the Co-based perpendicular magnetization film, which has a gradient of oxygen concentration in the thickness direction and is rich in oxygen on the medium surface side. As a result, a perpendicular magnetic recording medium with significantly improved durability was realized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a perpendicular magnetic recording medium manufactured according to the present invention, and FIG. 2 is a diagram showing the structure of a perpendicular magnetic recording medium manufactured according to the present invention.
FIG. 4 is a schematic diagram of an example of an apparatus for forming an oxide film containing Co as a main component by sputtering, and FIG. 3(a) is a schematic diagram of Example 1, FIG. 3(B) is a schematic diagram of the case where the oxygen partial pressure is changed, and FIG. 5 is a diagram of Example 3. Fig. 6 shows the concentrations of various elements in the JI and I directions of each perpendicular magnetic recording medium of Comparative Example 1 by Auger electron r spectroscopy (Fig. 3 (a), (h)) and ESCA (Fig. 5).
6). 11: Jl magnetism 1 (body + 2: inner magnetic film with Co as 11 components + 3: co 1
Oxide film as a component 21: Unwinding roll 22: Nori roller 24: Gyan 25: Free roller 26 2nd winding roll 27: Life-proof plate 28: Vapor deposition material 28 Nil pressure point 30: f (r beam 31: Electric f planning 1c 32: Acid inlet 33: 1z Held or Co/Hold alloy metal tarquent 34: Oxygen introduction pipe 35: Ar introduction pipe 36: 'f (i, separation vacuum gauge 37: Oxygen concentration curve (oxygen partial pressure 0. 05pa) 38:C
r concentration curve 38: Oxygen concentration curve (oxygen partial pressure 0.02 Pa) 40: Oxygen concentration curve (oxygen partial pressure 0.12 Pa) 51: Trivalent Coe
degree curve 52: oxygen concentration curve 53: Cr concentration curve 61: oxygen concentration curve 62: Cr concentration curve

Claims (7)

[Claims] (1) In a magnetic recording medium in which at least a perpendicularly magnetized film mainly composed of Co and an oxide film mainly composed of Co are laminated in the above order on a nonmagnetic substrate, the oxide film mainly composed of Co is The oxygen content has a gradient in the thickness direction, and the oxygen content on the outermost surface of the medium of the oxide film is greater than the oxygen content on the interface side with the perpendicular magnetization film mainly composed of Co. Features of perpendicular magnetic recording media. (2) A patent claim in which the oxygen content on the outermost surface side of the medium of the oxide film mainly composed of Co is 1.5 times or more the oxygen content on the interface side with the perpendicularly magnetized film mainly composed of Co. range 1
The perpendicular magnetic recording medium described in . (3) The outermost layer of the oxide film mainly composed of Co is Co_3
The perpendicular magnetic recording medium according to claim 1 or 2, comprising an oxide crystal layer containing an O_4 spinel crystal phase as a main component. (4) The oxide film mainly composed of Co has at least two different crystallographic phases in the thickness direction, and among these, the phase that exists on the outermost surface is a spinel phase, and at least one phase that does not have a spinel structure Amorphous metal in the X-ray diffraction sense, or a mixed phase of an amorphous metal and a microcrystalline metal in the X-ray diffraction sense, or a mixed phase of an amorphous metal, a microcrystalline metal, and spinel crystals in the X-ray diffraction sense. A magnetic recording medium according to claim 3. (5) Claims 1 to 5, wherein the perpendicularly magnetized film is a perpendicularly magnetized film whose main component is Co, which is formed by a physical vapor deposition process using a vacuum chamber, such as vacuum evaporation, sputtering, or ion plating. 4. The perpendicular magnetic recording medium according to any one of item 4. (6) Claims 1 to 3 in which the metal composition or metal composition ratio of the perpendicularly magnetized film mainly composed of Co is different from the metal composition or metal composition ratio of the oxide film mainly composed of Co.
The perpendicular magnetic recording medium according to any one of item 5. (7) A perpendicular magnetization film containing at least Co as a main component is formed on a flexible non-magnetic substrate by a physical vapor deposition process, and an oxide film containing Co as a main component is further formed on top of the perpendicular magnetization film by a physical vapor deposition process in an oxygen gas atmosphere. A method of manufacturing a perpendicular magnetic recording medium in which the oxide film is formed continuously by the method, wherein the direction of flow of oxygen gas near the part where the oxide film is attached and formed is opposite to the running direction of the substrate on which the perpendicular magnetization film is already formed. A method of manufacturing a perpendicular magnetic recording medium characterized by: