JPH09147342A - Magnetic recorder, magnetic recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the counter diffusion of silicon in a silicon substrate and magnetic substance particles in a granular magnetic layer due to heat by forming a diffusion preventing layer of a nonmagnetic material between the silicon substrate and the granular magnetic layer contg. a nonmagnetic material besides the magnetic substance particles. SOLUTION: A diffusion preventing layer 42 of SiO2 is formed on a single- crystalline silicon substrate 41 and a granular magnetic film 43 contg. fine magnetic substance particles 43g dispersed in SiO2 43s is formed on the layer 42. The magnetic film 43 is grown in an atmosphere of Ar while keeping the substrate at room temp. and then the crystallinity of the magnetic substance particles is improved by heat treatment in an inert gaseous atmosphere. A protective film 44 of carbon is formed on the magnetic film 43 and the top of the film 44 is coated with a lubricant to obtain the objective recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording device, a magnetic recording medium and a method for manufacturing the same, and more particularly, to a magnetic recording device used for an external storage device of an information processing device and a magnetic recording medium on a silicon substrate. The present invention relates to a magnetic recording medium having a layer structure and a manufacturing method thereof.

[0002]

2. Description of the Related Art In a magnetic recording apparatus, the recording / reproducing characteristics of a magnetic film greatly change depending on the size of crystal grains of a magnetic material in a magnetic film, the distance between crystal grains, the crystal orientation, and the like. The crystal size of the magnetic film can be changed by the substrate temperature during film growth and the heat treatment after film formation.

For example, in a granular magnetic film (Fe-SiO ₂ ) in which magnetic fine particles are dispersed in a SiO ₂ film, the crystallinity of the magnetic fine particles is controlled by appropriately controlling the substrate temperature during film formation. Appl. Phys. Lett. 52 (6), 512 (19)
88) and US Pat. No. 4,973,525. From this, the granular magnetic film has a small amount of precipitates of the magnetic material in the film just by forming the film, and the coercive force tends to be difficult to develop. It can be seen that in order to increase the coercive force, it is necessary to perform heat treatment after growth to increase the volume of precipitates.

On the other hand, a Ni-P plated substrate has been mainly used as a substrate for a magnetic recording medium, but the Ni-P layer on the surface of the substrate is crystallized by heating at 300 ° C. or more, resulting in smoothness. It is not suitable for heat treatment at high temperature because of problems such as damage and magnetization. Also,
With the recent trend toward miniaturization, ICs are being used in magnetic disk drives.
It is considered to be the same size as the card. In this case, the thickness of the magnetic disk needs to be 3 mm or less. In this case, the thickness of the substrate is required to be 0.3 mm or less, but using a Ni-P plated substrate has a problem in mechanical strength.

As described above, in order to further reduce the thickness and smooth the magnetic recording medium, a glass substrate or a single crystal silicon substrate has been studied in place of the Ni-P plated substrate. For example, a single crystal silicon substrate is used, and chrome (C
It has been proposed in JP-A-59-96538 to grow an r) layer, a magnetic film and a protective film in this order and use these as a magnetic recording medium.

[0006]

From the above, it is conceivable to grow the Fe—SiO ₂ granular magnetic film on the single crystal silicon substrate and then heat-treat the granular magnetic film. In this case, it is presumed that SiO ₂ covering the iron granular has an effect of preventing the reaction between the silicon substrate and the granular.

However, according to the experiments of the present inventor, when the granular magnetic film on the silicon substrate was heated at a high temperature,
The magnetic atoms and silicon atoms diffuse with each other through the surfaces of the grain boundaries of the granular particles to form paramagnetic silicon compounds, which reduces the saturation magnetization (Ms) of the magnetic recording medium. In particular, in a magnetic recording medium that requires a low tBr (t; thickness of magnetic layer, Br; magnitude of residual magnetization), which is premised on the use of an MR head, the amount of magnetic material in the magnetic film is absolute. It is a serious problem that magnetic materials form silicon compounds.

On the other hand, in a magnetic recording medium in which a plurality of layers made of different materials are formed on a substrate, if the layers are formed and then heated, there is a risk of film peeling due to the difference in thermal expansion coefficient. An object of the present invention is to prevent a reaction between silicon of a silicon substrate and a magnetic material of a granular magnetic film to suppress a decrease in coercive force, a magnetic recording medium without film peeling, a method for manufacturing the same, and such a magnetic recording. It is to provide a magnetic recording device having a medium.

[0009]

As illustrated in FIG. 1 (c), a silicon substrate 41 and a diffusion prevention layer 42 formed on the silicon substrate 41 and made of a non-magnetic material containing no magnetic particles are provided. The magnetic recording medium is characterized in that it has a granular magnetic layer 43 formed on the diffusion prevention layer 42 and containing the non-magnetic material and magnetic particles.

The non-magnetic material is silicon dioxide. The product of the thickness of the granular magnetic layer 43 and its residual magnetization is 100 Gm or less. Further, the magnetic particles are characterized by being made of a material containing any one of iron, cobalt and nickel, or a material containing at least one of iron, cobalt and nickel.

As illustrated in FIG. 9, the magnetic recording apparatus has the magnetic recording medium 46 and a magnetic head 47 for writing or reading the magnetic recording information written in the magnetic recording medium 46. Solve by.
As illustrated in FIGS. 1 (a) and 1 (b), a silicon substrate 41 is used.
Growing a diffusion prevention layer 42 made of a non-magnetic material on the diffusion prevention layer 42 without including magnetic particles; and forming a granular magnetic layer 43 containing the magnetic particles and the non-magnetic material on the diffusion prevention layer 42. And a step of heating the silicon substrate 41, the diffusion preventing layer 42, and the granular magnetic layer 43.

In this method, the heating temperature is set to 300
It is characterized in that the temperature is above ℃. (Operation) According to the present invention, the diffusion prevention layer made of the non-magnetic material is formed between the granular magnetic layer containing the non-magnetic material and the magnetic particles and the silicon substrate. The thermal diffusion between silicon and the magnetic particles in the magnetic recording layer is prevented by the diffusion prevention layer.

Therefore, since the compound of magnetic substance and silicon is not generated, the magnetic substance does not decrease in the magnetic recording layer, and a magnetic recording medium having high coercive force and high recording density can be obtained. Moreover, since the granular magnetic layer excluding the magnetic fine particles and the diffusion prevention layer are made of the same non-magnetic material, the granular magnetic layer and the diffusion prevention layer do not cause a difference in stress due to heat, and thus the film may peel off. It is possible to obtain a stable layer structure. The non-magnetic layer is, for example, a silicon oxide film, and the magnetic particles are, for example, iron, cobalt, and nickel. The adhesion between the silicon dioxide layer and the silicon substrate is extremely good, and there is no risk of film peeling due to heat.

It is also conceivable that the diffusion prevention layer is made of a non-magnetic material having the same coefficient of thermal expansion and a different composition as the non-magnetic material forming the granular magnetic layer. However, since it takes time and effort to alloy the two non-magnetic materials separately, it is preferable that the non-magnetic materials are the same. When the product of the thickness of the granular magnetic layer having such a structure and the amount of residual magnetization thereof is 100 Gm or less, an optimum magnetic recording medium for a magnetoresistive head can be obtained.

Even if the silicon substrate is heated at 1000 ° C., it will not be magnetized or deformed.

[0016]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing a manufacturing process of a magnetic recording medium according to an embodiment of the present invention. First, as shown in FIG. 1A, a single crystal silicon substrate 41
A diffusion prevention layer 42 made of SiO ₂ (silicon dioxide) is formed on the top of the diffusion prevention layer 42 to a thickness of 100 nm by sputtering or thermal oxidation.

Next, as shown in FIG. 1B, a diffusion preventing layer 4 is formed by sputtering a granular magnetic film 43 in which magnetic fine particles 43g such as iron (Fe) are dispersed in SiO ₂ 43s.
2 to have a thickness of 30 nm. Granular magnetic film 43
Was grown in an Ar atmosphere at a substrate temperature of room temperature. Thereafter, as shown in FIG. 1 (c), the crystallinity of the magnetic fine particles is improved by heat treatment in an inert gas atmosphere.

Thereafter, as shown in FIG. 1D, a protective film 44 made of carbon (C) is formed on the granular magnetic film 43 to a thickness of 15 nm. After this, on the protective film 44
The lubricant is applied to complete the magnetic recording medium. In order to examine the effect of heat treatment on the magnetic recording medium having the above structure, a comparative sample having no diffusion prevention layer was prepared. This comparative sample, as shown in FIG.
1. The granular magnetic film 52 is directly formed on the first magnetic field without a diffusion prevention layer.
Is formed. Granular magnetic film 52
Is obtained by dispersing 53 g of magnetic fine particles in SiO ₂ 53 s. The manufacturing conditions of this comparative sample are the same as those of FIGS. 1 (a) and 1 (b) except for the diffusion prevention layer.

The granular magnetic layer 4 of each of the magnetic recording medium shown in FIG. 1B and the comparative sample shown in FIG.
It was tested how 3,53 was changed by the heat treatment. (Change in Saturation Magnetization) When the change in the value of saturation magnetization (Ms) due to heat treatment was examined, the results shown in FIG. 3 were obtained. In FIG. 3, the solid line shows the heating temperature / saturation magnetization characteristic of the magnetic recording medium shown in FIG. 1 (c), and the broken line shows the heating temperature / saturation magnetization characteristic of the comparative sample shown in FIG. The horizontal axis shows the heat treatment temperature, and the vertical axis shows the magnitude of the saturation magnetization of the magnetic recording medium after the heat treatment temperature.

As is apparent from the broken line in FIG. 3, in the comparative sample having no diffusion preventing layer, the value of Ms decreased with increasing temperature of the heat treatment. The heat treatment of the comparative sample is not preferable because the reduction of Ms of the magnetic recording medium brings about the reduction of the reproduction output, and the Ms remains low even without the heat treatment. As is clear from the solid line in FIG. 3, according to the magnetic recording medium of the present embodiment, the value of Ms rises as the heating temperature rises. The higher Ms is, the more advantageous it is to obtain a high output during information reproduction.

The reason why the change in Ms due to the heat treatment is different between the case where the SiO ₂ diffusion preventive layer 42 is interposed and the case where the SiO ₂ diffusion preventive layer 42 is not interposed between the silicon substrate and the granular magnetic film is as follows. That is, in the comparative sample, the amount of the magnetic material was reduced because the magnetic fine particles 53 g of iron and the silicon in the silicon substrate 51 were mutually diffused by heat to generate silica iron. In the granular magnetic film 53 of the comparative sample, it is considered that silicon element and iron diffuse through the boundaries between the magnetic fine particles 53g and the SiO ₂ 53s.

On the other hand, in the present embodiment shown in FIG. 1 (b), the diffusion preventing layer 42 prevents mutual diffusion of silicon and the magnetic fine particles 43g due to heat, so that the amount of the magnetic substance does not decrease, and moreover the heat treatment is performed. The particles became large. Next, as shown in FIG. 1 (b), the granular magnetic film 43 formed on the silicon substrate 41 via the SiO ₂ diffusion prevention layer 42.
Then, as shown in FIG. 2, it was examined by XRD (X-ray diffraction) measurement how the composition of each crystal of the granular magnetic film 53 directly formed on the silicon substrate 51 was changed by the heat treatment.

FIG. 4 shows the granular magnetic film 4 immediately after being formed on the silicon substrate 41 via the SiO ₂ diffusion preventing layer 42.
3 shows the XRD measurement result of No. 3. Further, FIG. 5 shows an XRD measurement result of the granular magnetic film 53 immediately after being directly formed on the silicon substrate 53. Comparing FIG. 4 and FIG. 5, there is no significant difference between the X-ray diffraction spectra of the granular magnetic films 43 and 53. That is, in the as-deposited state, whether or not the SiO ₂ diffusion preventing layer 42 containing no iron is present does not cause a large difference in the crystallinity of the granular magnetic films 43 and 53. The reason why the intensity of the X-ray diffraction lines of both granular magnetic films 43 and 53 is weak is that both granular magnetic films 4 in the as-deposited state.
It is considered that the crystal grains of magnetic substance grains 43g and 53g in 3,53 are very small.

Next, the granular magnetic film is formed at 800 ° C. for 10 minutes.
The XRD measurement results after heating for minutes are shown in FIGS. 6 and 7.
FIG. 6 shows the XRD measurement results after heating the granular magnetic film 43 of the magnetic recording medium shown in FIG. 1 (b). According to this measurement result, only the α-Fe diffraction line appears as a peak, and the peak is large. Moreover, the peak of the compound of iron and silicon is not observed. this is,
It is considered that by forming the SiO ₂ diffusion layer 42 between the silicon substrate 41 and the granular magnetic film 43, mutual diffusion of silicon atoms in the silicon substrate 41 and iron atoms in the granular magnetic film 43 was blocked. The reason why Ms is increased by the heat treatment at 800 ° C. for 10 minutes in the solid line of FIG. 3 is that this ferromagnetic α-Fe is not decreased.

FIG. 7 shows the XRD measurement results after heating the comparative sample shown in FIG. According to this measurement result, only the diffraction line of the compound of iron and silicon appears as a peak. This is because body-centered cubic (bcc) -based iron (α-Fe), which was present as magnetic particles 53g in the granular magnetic film 53 in the as-deposited state, was converted into silicon atoms in the silicon substrate 51 by heat treatment. It is considered that this is because they are bonded to form silica iron. The reason why Ms is decreased by the heat treatment at 800 ° C. for 10 minutes in the broken line of FIG. 3 is that this ferromagnetic α-Fe is decreased. (Change in coercive force) An experiment was conducted to see how the coercive force of the magnetic recording medium of the granular magnetic film 43 in the state shown in FIG. 1 (b) was changed by heat treatment, and the results shown in FIG. 8 were obtained. Was given. In FIG. 4, the vertical axis represents the heating temperature and the vertical axis represents the coercive force Hc.

As is apparent from FIG. 8, the coercive force of the granular magnetic film 43 increased as the heating temperature increased, and reached 800 oersted (Oe) at the heating temperature of 500 ° C. The heating time was 10 minutes. From the above, by interposing the diffusion prevention film between the granular magnetic film and the silicon substrate, it is possible to obtain a magnetic recording medium having a high reproduction output and a coercive force suitable for a high recording density by heat treatment. Recognize.

When a film in which magnetic particles such as nickel (Ni), cobalt (Co) and the like are dispersed in a SiO ₂ film is used as a granular magnetic film, a space between the granular magnetic film and the silicon substrate is also used. By interposing a non-magnetic film in, it is possible to prevent the generation of the compound of magnetic fine particles and silicon. By the way, according to the magnetic recording medium shown in FIG. 1 (d), both the diffusion prevention layer 42 and the granular magnetic film 43 are made of the same SiO ₂ , and the adhesion between the SiO ₂ and the silicon substrate 41 is good. Even if heated at a high heat of 300 ° C. or higher, film peeling due to thermal expansion does not occur.

In addition to SiO ₂ , a non-magnetic material such as Si ₃ N ₄ , SiON, Cu or Cr may be used. Next, a magnetic recording device using the magnetic recording medium having the layer structure shown in FIG. 1D for a magnetic disk will be briefly described with reference to FIG. As shown in FIG. 9, the magnetic recording drive 45 includes a magnetic disk 46 and an M disk.
It has a slider 47 having an R head and a spring arm 48 for supporting the slider 47.

[0029]

As described above, according to the present invention, the diffusion prevention layer made of the nonmagnetic material is formed between the granular magnetic layer containing the nonmagnetic material and the magnetic particles and the silicon substrate. Therefore, the mutual diffusion of the silicon in the silicon substrate and the magnetic particles in the granular magnetic layer due to heat can be prevented by the diffusion prevention layer.

Therefore, since a compound of magnetic substance and silicon is not produced, the magnetic substance is not reduced, and a magnetic recording medium having high coercive force and high recording density can be obtained.
Moreover, since the granular magnetic layer excluding the magnetic fine particles and the diffusion prevention layer are made of the same material, the granular magnetic layer and the diffusion prevention layer do not cause a difference in stress due to heat, and thus the film does not peel off and is stable. It is possible to obtain a layered structure.

Further, since the product of the thickness of the silicon oxide layer containing the magnetic fine particles and the residual magnetization is set to 100 Gμm or less, it can be applied to the magnetoresistive head. Furthermore, when the magnetic fine particles include any one of iron, cobalt, and nickel, the atoms and silicon are easily combined by the heat treatment, so that the effect of the diffusion preventing layer becomes remarkable.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a comparative sample when the present invention is not applied.

FIG. 3 is a diagram showing a relationship between a heating temperature and a saturation magnetization for each of a magnetic recording medium formed on a silicon substrate via an SiO ₂ film and a magnetic recording medium formed directly on the silicon substrate.

FIG. 4 is a diagram showing an X-ray diffraction result immediately after growing a granular magnetic layer on a silicon substrate via a SiO ₂ film.

FIG. 5 is a diagram showing an X-ray diffraction result immediately after growing a granular magnetic layer directly on a silicon substrate.

FIG. 6 is a diagram showing an X-ray diffraction result of the granular magnetic layer after heating the granular magnetic layer formed on a silicon substrate via a SiO ₂ film at 800 ° C. for 10 minutes.

FIG. 7 is a diagram showing an X-ray diffraction result of a granular magnetic layer directly formed on a silicon substrate after being heated at 800 ° C. for 10 minutes.

FIG. 8 is a diagram showing a relationship between a heating temperature and a coercive force of a magnetic recording medium formed on a silicon substrate via an SiO ₂ film.

FIG. 9 is a plan view showing an example of a magnetic recording device having a magnetic recording medium according to an embodiment of the present invention.

[Explanation of symbols]

41 Silicon Substrate 42 Diffusion Prevention Layer 43 Granular Magnetic Layer 43s SiO ₂ Film 43 g Magnetic Fine Particles 44 Protective Film

Front page continuation (72) Iwao Okamoto Iwaoka Okamoto 1015 Kamiodanaka, Nakahara-ku, Kanagawa Prefecture, Fujitsu Limited Fujitsu Limited

Claims (7)

[Claims] 1. A silicon substrate, a diffusion prevention layer made of a non-magnetic material containing no magnetic material formed on the silicon substrate, and a non-magnetic material and magnetic particles formed on the diffusion prevention layer. And a granular magnetic layer containing the magnetic recording medium. 2. A magnetic recording medium, wherein the non-magnetic material is silicon dioxide. 3. The magnetic recording medium according to claim 2, wherein the product of the thickness of the granular magnetic layer and its residual magnetization is 100 Gμm or less. 4. The magnetic particles are iron, cobalt or nickel, or at least one of iron, cobalt and nickel.
The magnetic recording medium according to claim 2, wherein the magnetic recording medium is composed of a material including a kind. 5. A magnetic recording comprising the magnetic recording medium according to claim 1, 2, 3 or 4, and a magnetic head for writing or reading magnetic recording information written in the magnetic recording medium. apparatus. 6. A step of growing a diffusion prevention layer made of a non-magnetic material on a silicon substrate without including magnetic particles, and a granular magnetic layer containing magnetic particles and the non-magnetic material on the diffusion prevention layer. And a step of heating the silicon substrate, the diffusion barrier layer, and the granular magnetic layer, the method of manufacturing a magnetic recording medium. 7. The method of manufacturing a magnetic recording medium according to claim 6, wherein the heating temperature is 300 ° C. or higher.