JPH0963036A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic recording medium fit for high recording density by imparting a structure formed by dispersing ferromagnetic fine particles having a prescribed compsn. in a carbon-base thin film. SOLUTION: This magnetic recording medium has a structure formed by dispersing ferromagnetic fine particles of Co, Fe, Ni or an alloy of them in a carbon-base thin film. In order to produce the magnetic thin film medium, sputtering, vacuum deposition or CVD is adopted. The base of the amorphous film in which the metallic fine particles are embedded is carbon and a component such as hydrogen, Si or β-Si02 may be contained in the film. Isolated magnetic fine particles excellent in magnetic insulating property can be dispersed in a diamondlike carbon film used as a protective film so far.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium capable of high density recording.

[0002]

2. Description of the Related Art In recent years, in order to increase the recording density of alloy magnetic thin film media for magnetic recording manufactured by sputtering or vacuum evaporation method, the recording bit is reduced to 0.2 μm or less,
It is approaching the crystal grain size order. It is becoming difficult to record such fine bits stably when using a “uniform” magnetic thin film whose magnetization is uniform over the entire film and magnetization reversal easily occurs due to domain wall motion. . Therefore, it is necessary to develop a magnetic thin film in which the ferromagnetic regions are magnetically isolated and which has a “fine particle type” film structure as if it were an aggregate of ferromagnetic fine particles. this is,
Thin film for perpendicular magnetic recording (S. Iwasaki, K. Ouchi and N. Hon
da: IEEE Trans. Magn., MAG-16 (1980) p.1111-1113
), The longitudinal recording thin film (Y. Yogi, TA
Nguyen, SE Lambort, GL Gorman and G. Casill
o: IEEE Trans. Magn., MAG-26 (1990) p.1578-1580)
It is said that high density is essential in each case.

C currently used for in-plane magnetic recording
In a so-called CoCr-based alloy thin film such as oCrTa, CoCrPt-based thin film, or CoCr for perpendicular magnetic recording, it has been found that a composition separation phenomenon that separates a Co-rich ferromagnetic region and a Cr-rich nonmagnetic region occurs. (Y. Maeda and K. Takahasi: J. Appl.Phy
s., 68 (1990) p.4571-4759). In recent years, a method of forming a “fine particle type” magnetic thin film by utilizing this phenomenon has been widely studied. In both the in-plane magnetic recording and the perpendicular magnetic recording, in order to achieve high recording density, it is necessary to disperse the magnetic fine particle structure finer and more uniformly.

Conventionally, as described above, it is known that a composition separation structure can occur in a CoCr alloy thin film, but since this composition separation phenomenon is a statistical phenomenon, all the ferromagnetic regions are covered. It was difficult to isolate magnetically.

Recently, in the above in-plane type alloy thin film,
Medium noise due to magnetic fluctuation due to formation of head-on domain is a major issue in medium development. To reduce noise due to this head-on domain, a method of reducing magnetostatic energy due to opposing magnetization is effective.
A method of reducing the film thickness is effective for reducing the magnetostatic energy, and at present, a method of reducing the film thickness to reduce the medium noise is mainly used. For this reason, currently
In the in-plane magnetic recording medium, a film thickness of about 20 to 30 nm is mainly studied. On the other hand, even in the perpendicular magnetic recording medium, a magnetic recording medium of about 50 nm has been studied in order to realize the perpendicular magnetic recording system by effectively acting the perpendicular component of the head magnetic field on the medium.

In a high-density magnetic recording state, the magnetic field generated from the medium sharply decreases in the vertical direction of the medium. Therefore, the magnetic head for reproducing by detecting the magnetic field generated from the medium has a head-medium distance. The situation is inevitably reduced. Currently, the flying height of the magnetic head is 1000Å
The following has come to be realized. In such a state in which the flying height of the head is significantly reduced, the tribological characteristic between the head and the medium is a decisive factor that determines the reliability of the magnetic disk device. As described above, in thin film magnetic media of recent years, the film thickness must be reduced,
In such a case, since the mechanical strength of the film cannot be sufficiently improved, DLC (Diamond Like Carbon), SiO
A protective film such as ₂ is formed on the magnetic thin film. Since this protective film substantially increases the distance between the head and the medium, it is an obstacle to higher recording density.

As described above, the conventional thin film medium has the following drawbacks. 1) It is difficult to achieve magnetic insulation effective for noise reduction. 2) As the film thickness is reduced, it is difficult to improve the mechanical strength of the metal magnetic thin film. 3) In order to protect the magnetic film, there is no choice but to form a protective film.
This protective film increases the distance between the head and the medium and is an obstacle to higher density.

[0008]

The present invention has been proposed in order to improve the above-mentioned drawbacks, and its purpose is to have an extremely fine particle type film structure essential for realizing a high medium to noise ratio. , Furthermore, no protective film is required, or sufficient durability can be obtained with only an extremely thin protective film,
An object is to provide a magnetic recording thin film medium for high recording density.

[0009]

In order to solve the above problems, according to the present invention, ferromagnetic fine particles made of cobalt, iron, nickel or an alloy thereof are dispersed in a thin film containing carbon as a main component. A magnetic recording thin film medium having a structure or a thin film containing carbon as a main component has a structure in which alloy ferromagnetic fine particles containing these elements as a main component are dispersed. The sputtering method, the vacuum deposition method, and the CVD method are effective for producing the magnetic thin film medium having such a structure. Although the main component of the amorphous film in which the metal fine particles are embedded is carbon,
Even if the amorphous film contains elements such as hydrogen, Si, and SiO2β, the above problems can be solved.

In the present invention, since magnetic fine particles are embedded in a film mainly composed of carbon, which has been conventionally used as a protective film, not only magnetic insulation can be completely achieved but also a protective film is not required. It has excellent durability as a medium.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The feature of the present invention is that cobalt, iron, nickel,
Alternatively, alloy ferromagnetic fine particles containing these elements as main components are dispersed in a magnetic recording thin film medium having a structure in which ferromagnetic fine particles containing these alloys are dispersed, or in a thin film containing carbon as the main component. It is a thin film medium for magnetic recording characterized by having a different structure.

(Example) An RF sputtering method was adopted as a film forming method. Carbon was used as a target, and Co, Fe, and Ni pellets were arranged on the target so that the area ratio was 3% to form a film. Pure Ar for sputter gas
Gas was used. In the latter case, the CH ₄ flow rate was set to 20% of the Ar flow rate. The substrate temperature is 200 ° C,
A glass substrate was used as the substrate. RF power is 200W. A 500Å DLC composite film was prepared. Table 1 summarizes the magnetic characteristics measured by VSM. The saturation magnetizations of the samples doped with Co, Fe, Ni, and Co + Fe (Co / Fe = 2) are 380, 420, 220, respectively.
400 emu / cc was obtained, and a relatively large value was obtained when Co and Fe were used. The coercive force is 1000
A degree of Oe was obtained. The results of evaluating the surface roughness of the DLC film doped with Co by AFM (Atomic Force Microscopy) are shown in FIG. R _max was about 10Å, and a remarkably flat surface was obtained.

[0013]

As described above, according to the present invention, the isolated magnetic fine particles excellent in magnetic insulation due to the metal-doped film are formed in the DLC film which has been conventionally used as a protective film. There is an effect that it can be dispersed and a magnetic recording medium suitable for high recording density can be formed.

[Brief description of drawings]

FIG. 1 shows the results of measuring the surface roughness of a Co-doped DLC film of the present invention.

Continuation of the front page (72) Inventor Yasuko Ando 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (2)

[Claims] 1. A magnetic recording medium having a structure in which ferromagnetic fine particles made of cobalt, iron, nickel, or an alloy thereof are dispersed in a thin film containing carbon as a main component. 2. A magnetic recording medium having a structure in which alloy ferromagnetic fine particles containing cobalt, iron or nickel as a main component are dispersed in a thin film containing carbon as a main component.