JP2857136B2 - Magnetic recording medium and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having a magnetic thin film provided on a non-magnetic support, and more particularly to a highly reliable magnetic recording medium having excellent wear resistance. It relates to a recording medium. 2. Description of the Related Art With the increase in capacity of magnetic recording devices, magnetic recording media used therein are required to have increasingly higher recording density characteristics and higher reliability. Conventionally, a coating type magnetic recording medium in which a magnetic powder such as γ-Fe ₂ O ₃ is dispersed in a resin binder and applied on a non-magnetic support has been generally used. In response to the trend, thin-film magnetic recording media in which a magnetic thin film is formed on a non-magnetic substrate by a vapor deposition method, a plating method, a sputtering method, or the like have been receiving attention. In this thin-film type magnetic recording medium, the magnetic layer can be made thinner, and since the magnetic layer does not contain a non-magnetic resin binder, a higher magnetic flux density can be achieved. Density is possible. However, in this type of magnetic recording medium, the problem that the magnetic layer is destroyed due to the sliding contact between the magnetic recording medium and the magnetic head is more likely to occur than in the case of the coating type magnetic recording medium. On the other hand, it is important to treat the surface of the magnetic layer in order to provide sufficient wear resistance. For example, in a magnetic disk drive, the magnetic head and the medium make sliding contact at the start and stop of rotation of the magnetic disk medium,
So-called contact start / stop (hereinafter CSS)
) System has been adopted, and abrasion resistance sufficient to withstand this is required.
Conventionally, in order to ensure the wear resistance of such a magnetic recording medium, Al ₂ O ₃ , SiO ₂ , TiO ₂ , Si ₃ N ₄ , W
There has been proposed a method of forming a protective film made of a material having high hardness such as C, TiC, SiC, and B ₄ C on a magnetic layer (Japanese Patent Publication No. 55-39047, Japanese Patent Application Laid-Open No. Sho 53-21901,
JP-A-53-21902, JP-A-58-185029,
JP-A-59-188835). The above-described protective film is usually formed on a magnetic thin film by a sputtering method. However, these protective films often do not have sufficient adhesion to the magnetic thin film, and the protective film peels off due to sliding contact with the magnetic head. Other portions of the film were scraped off and even the magnetic thin film was destroyed. When the magnetic thin film is a thin film containing γ-Fe ₂ O ₃ as a main component and a protective film is to be formed on the thin film by a sputtering method,
Once a film containing α-Fe ₂ O ₃ or Fe ₃ O ₄ as a main component is formed by a sputtering method, the film is taken out of a sputtering chamber, placed in an atmosphere furnace, and subjected to a heat treatment such as reduction and oxidation to perform γ- A method of forming a thin film containing Fe ₂ O ₃ as a main component, placing the thin film again in a sputtering chamber, and forming a protective film by sputtering is employed. However, this method has to be taken in and out of the sputtering chamber, and the process becomes complicated,
This is a problem in mass production. [0005] An object of the present invention is to form a protective film on a magnetic thin film with good adhesion, thereby having excellent wear resistance.
An object of the present invention is to provide a highly reliable magnetic recording medium. Also,
Another object is to provide a magnetic recording medium having excellent abrasion resistance and high reliability in which a protective film made of an oxide is formed on a thin film made of a magnetic oxide in a simple manner with good adhesion. is there. According to the present invention, there is provided a magnetic recording medium comprising a non-magnetic support, a thin oxide magnetic film formed on a non-magnetic support, and a protective film. the oxide magnetic film and the protective film thickness is at least 100Å between thin film and protective film are you characterized by the presence of a solid solution region. According to the magnetic recording medium of this, greatly enhance the bonding strength and adhesion between the magnetic thin film by the formation of solid solution region and the protective film, the abrasion resistance as can be seen from the CSS test described below is increased The protective film does not peel off, and a highly reliable magnetic recording medium having a long life can be provided. According to the method of manufacturing a magnetic recording medium of the present invention, a target oxide magnetic thin film, a precursor magnetic thin film thereof, or a target oxide magnetic thin film precursor thin film is formed on a nonmagnetic support. Abrasion resistant oxide or its precursor
To form a more becomes thin, by heat treatment at a predetermined temperature, while the magnetic thin film and abrasion resistant protective layer for the purpose both of the above films, respectively, both with cause diffusion between these films At a boundary between the two solid solution regions having a thickness of 100 ° or more . According to this method,
Diffusion occurs between the magnetic thin film and the protective film by the heat treatment, and the adhesion between the two is enhanced, whereby the above-described excellent magnetic recording medium can be provided. According to the method of the present invention, the target oxide magnetic thin film, its precursor magnetic thin film or precursor thin film and the protective film or its precursor film,
Since it is sufficient to perform heat treatment after forming a film sequentially, for example, when performing a vacuum film formation such as a sputtering method, a precursor oxide film of a magnetic thin film is formed by a sputtering method as in the conventional method, and a vacuum leak is performed. Then, after forming a predetermined magnetic thin film, the complicated procedure of loading the film again into the sputtering apparatus and forming the protective film by sputtering is simplified. That is, in the method of the present invention, the sputter film formation is performed continuously without using a vacuum litter, and then the treatment is performed in a heat treatment furnace, which is efficient. Nevertheless, as described above, the characteristics of the magnetic recording medium obtained by the method of the present invention are superior to those of the conventional one. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to sufficiently improve the adhesion and abrasion resistance intended by the present invention, the thickness of the solid solution region must be 100 mm.
Or more, preferably 200 ° or more. Thereby, C resistance
The SS characteristics are sufficiently improved. The thickness of the solid solution region is controlled by the heat treatment temperature and time. The higher the heat treatment temperature,
Alternatively, the longer the heat treatment time, the larger the thickness of the solid solution region. Usually, the temperature of the heat treatment is performed at 100 ° C. or higher.
Below this, it takes too much time to form a solid solution region having a predetermined thickness. A typical example of the magnetic oxide forming the magnetic thin film is γ-Fe ₂ O ₃ or an oxide mainly containing γ-Fe ₂ O ₃ . Such a thin film is formed, for example, by forming an α-Fe ₂ O ₃ thin film by a sputtering method, reducing this in a reducing atmosphere furnace to form an Fe ₃ O ₄ thin film, and further oxidizing the same in an oxidizing atmosphere furnace. To form a γ-Fe ₂ O ₃ thin film. In another method, a Fe ₃ O ₄ thin film is formed by a sputtering method, and this is oxidized in a furnace in an oxidizing atmosphere to form a γ-F
This is performed by forming an e ₂ O ₃ thin film. In one embodiment of the present invention, the above γ-F
Conversion to an e ₂ O ₃ thin film is performed by using α-Fe ₂ O ₃ or Fe ₃ O ₄
This is performed after forming a protective film or a thin film of a precursor thereof on the surface of the thin film. Α-Fe ₂ O ₃ or Fe
_{While 3} O ₄ is converted to a γ-Fe ₂ O ₃ magnetic thin film, the protective film or its precursor is converted to a protective film, and a solid solution layer of both is formed between the two films. Al ₂ O ₃ , TiO ₂ , SiO _2
2 , Al, Ti, Si, etc. can be used, which are converted to a wear-resistant protective film such as Al ₂ O ₃ , TiO ₂ , SiO ₂ during heat treatment. The protective film must be not only sufficiently abrasion resistant but also capable of forming a solid solution region by diffusion with the magnetic thin film. The method of the present invention can be typically performed by a sputtering method. In the present invention, F
e, a target such as α-Fe ₂ O ₃ , Fe ₃ O ₄ , and A
1, a target such as Al ₂ O ₃ is set, and these are sputtered on a nonmagnetic support to form a film. Next, each layer is reduced or oxidized in a heat treatment furnace to change each layer into a predetermined magnetic thin film and a wear-resistant oxide, and the interface between them is made into a solid solution region. As described above, this method is superior to the conventional method. FIG. 3 illustrates this point. FIG. 3A shows the method of the present invention, and FIG. 3B shows the conventional method. As shown in the figure, the steps indicated by double frames in the conventional method are more numerous than the method of the present invention. As described above, according to the present invention, since the steps are simplified, the manufacturing time of the magnetic recording medium is reduced. The thickness of the solid solution region can be measured by ESCA analysis, Auger analysis, RBS analysis or the like.
For example, Auger analysis is performed by observing the profile of atoms constituting the protective film and the magnetic thin film in the thickness direction. FIG. 1 shows an example in which an Al ₂ O ₃ protective film is formed on a Co—Ni thin film. The half width d of the portion where the distributions of Al and Co overlap can be considered as a solid solution region. However, even when there is no solid solution region, d is not zero but 20 to 100 [deg.] Due to the resolution of the Auger analyzer. (Depending on each device). Therefore, the actual thickness of the solid solution region is a value obtained by subtracting this value from d, that is, the half width when there is no solid solution region is about 60 ° in the Auger analyzer used by the present inventors. Therefore, the actual thickness of the solid solution region is defined as d-60. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Alumite layer was formed as a substrate by anodic oxidation.
An aluminum alloy substrate having a thickness of μm was used. Outer diameter is 1
It has a disk shape of 30 mm, an inner diameter of 40 mm, and a thickness of 1.9 mm. Ar +
O ₂ atmosphere (mixing ratio 50%, degree of vacuum 5 × 10 ⁻³ Torr)
r) to form an α-Fe ₂ O ₃ film of 20
00 ° was formed. Further, an Al ₂ O ₃ protective film was formed thereon by a sputtering method. Next, the mixture was reduced in a hydrogen atmosphere furnace for 2 hours, and the α-Fe ₂ O ₃ film was turned into a Fe ₃ O ₄ film. At this time, the Al ₂ O ₃ film is also partially reduced to a film containing Al.
Table 2 shows the reduction temperature. 310 in air
° C., was oxidized for 1 hour Fe ₃ O ₄ film as γ-Fe ₂ O ₃ film, the protective film was the Al ₂ O ₃ film. FIG. 3A summarizes the above steps in a flowchart. On the other hand, in the conventional method, the result is as shown in FIG. 3B, and it can be seen that the step surrounded by a double square is omitted in the present invention and the manufacturing time of the magnetic recording medium is shortened. For the completed magnetic disk, the thickness (d-60) of the solid solution region was measured by Auger analysis, and a CSS test was performed. The results are shown in Table 1. On the other hand, when a similar test was performed on a magnetic disk formed by the conventional method (FIG. 3B), d-60 = 0 and CSS = 14,000.
On the other hand, the superiority of the present invention is clear from Table 1. -CSS test A CSS test was performed using a Winchester type Mn-Zn ferrite head (load: 9.5 g). C
SS was performed by repeating the cycle shown in FIG.
The number of CSSs was the number of times until the recording / reproducing output became half or less of the initial value, and was performed up to 40,000 times. According to the results shown in Table 1, the formation of a solid solution region improves the CSS characteristics, and the solid solution region having a thickness of 100 mm or more significantly improves the CSS characteristics.
It can be understood that the above is further improved. [Table 1]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a method for measuring the thickness of a solid solution region. FIG. 2 is a diagram showing a CSS test method. FIG. 3 is a process comparison diagram between the method of the present invention and the conventional method.

Continuation of the front page (56) References JP-A-58-6528 (JP, A) JP-B-58-172 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5 / 72 G11B 5/66 G11B 5/84

Claims (1)

(57) [Claims] In a magnetic recording medium in which an oxide magnetic thin film is formed on a non-magnetic support and a protective film is further formed, the oxide magnetic thin film having a thickness of 100 mm or more between the oxide magnetic thin film and the protective film is protected. the magnetic recording medium area film is a solid solution and wherein Rukoto that Mashimasu exist. 2. 2. The protection film according to claim 1, wherein at least one of Al ₂ O ₃ , TiO ₂ and SiO ₂ is a main component.
3. The magnetic recording medium according to claim 1. 3. A first thin film made of a precursor of the oxide magnetic thin film (B), its precursor magnetic thin film (A), or a precursor of the oxide magnetic thin film (B) is formed on a nonmagnetic support, and the first thin film is formed on the first thin film. abrasion-resistant oxide or forming a second thin film made of a precursor thereof, followed by heat treatment, the first thin film and the oxide magnetic film (B), the second thin film wear resistance An oxide film , and the oxide magnetic thin film (B)
The above acid having a thickness of 100 ° or more between itself and the wear-resistant oxide film.
Magnetic thin film (B) and the wear-resistant oxide film
Forming a magnetic recording medium. 4. The first thin film is a thin film containing either α-Fe ₂ O ₃ or Fe ₃ O ₄ as a main component, and the second thin film is Al, A
l ₂ O _3, Ti, manufacturing method of a magnetic recording medium according to claim 3, characterized in that the at least one main component selected from the group consisting of _TiO 2, Si and SiO _2. 5. The magnetic thin film (B) contains γ-Fe ₂ O ₃ as a main component, and the wear-resistant oxide film is made of Al ₂ O ₃ , TiO ₂ and SiO ₂
5. The method for manufacturing a magnetic recording medium according to claim 3, wherein at least one of the following is used as a main component. 6. 6. The method according to claim 3, wherein the thickness of the solid solution region is 200 [deg.] Or more.