JPS61224119A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To enhance the in-plane orientation of an axis easy for magnetization even with use of an alloy thin film obtained by adding Ru to a Co-Ni alloy by composing the magnetic film of a Co-Ni alloy contg. Ru and regulating the ratio of the X-ray diffraction intensity I(002) of the (002) face to the X-ray diffraction intensity I(100) of the (100) face within the specified range. CONSTITUTION:A magnetic thin film layer to be formed on a substrate layer is composed of a Co-Ni alloy contg. 0.5-8atom% Ru and the ratio of the X-ray diffraction intensity I(002) of the (002) face to the X-ray diffraction intensity I(100) of the (100) face, namely I(002)/I(100) which is defined as R, is regulated to 0<=R<=3. Namely, an aluminum substrate or an aluminum alloy substrate is anodized in the liq. mixture contg. an acid such as chromic acid to form an alumite layer on the substrate surface. Then an Co-Ni-Ru thin film is formed on the substrate in an atmosphere contg. Gaseous Ar by sputtering, etc., and subsequently heat-treated to release N.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium and a method for manufacturing the same, and particularly relates to a magnetic recording medium in which a magnetic film layer having a high in-plane orientation of the axis of easy magnetization is formed on a substrate. The present invention relates to a recording medium and its manufacturing method.

[Prior art]

In recent years, as computers have become smaller and their processing power has increased, there has been a demand for further increases in the storage capacity of external memory devices. In order to satisfy this demand, it is necessary to further increase the recording density of the magnetic disks used in external memory devices, and for this reason, research into magnetic recording media with high recording density containing alloy magnetic thin films has been greatly promoted in recent years. ing.

As one example, it is known that a magnetic thin film obtained by starching a cobalt (CO)-nickel (Ni) alloy in an Ar and N2 atmosphere has good magnetic properties. It is also known that by adding Ru to a Co-Ni alloy, it has good magnetic properties and its corrosion resistance is also excellent. (Japanese Patent Publication No. 56-73413. Japanese Patent Application Publication No. 59-844
07) Generally, magnetic recording media have a hard underlayer provided on a substrate, a magnetic layer formed thereon, and a protective film further provided thereon, if desired.

[Problem that the invention seeks to solve]

Glass, which has been conventionally used as a substrate material, is difficult to work with and has low adhesion strength for magnetic films, which poses a problem in that it imposes considerable restrictions on the manufacturing and use conditions of magnetic recording media. Furthermore, although N1-P plated aluminum alloy base material, which is a typical aluminum base material with non-magnetic Ni alloy attached, has sufficient workability and impact resistance,
Since it becomes magnetized at temperatures above 0.000 to 250.degree. C. and causes noise, it is still subject to considerable restrictions on the manufacturing conditions of magnetic recording media.

On the other hand, an alloy thin film made by adding Ru to a Co-Ni alloy was considered to be useful as an in-plane magnetic recording medium with good corrosion resistance. However, the orientation of the easy axis of magnetization in the in-plane direction of the film was still insufficient, and the magnetic properties were unsatisfactory.

Furthermore, although alloy thin films produced by sputtering Co-Ni alloys in an Ar + N2 gas atmosphere have sufficient magnetic properties, they are inferior to magnetic films sputtered in pure Ar gas atmospheres in terms of corrosion resistance. It was a hindrance to the above.

[Means for solving problems]

In order to solve the problems of the prior art described above, the present invention provides a magnetic recording medium in which a magnetic film layer is formed on the surface of a disk-shaped substrate, in which the magnetic film layer is made of a Co-Ni based alloy containing Ru. , (002) plane X-ray diffraction intensity I (002'
) and the X-ray diffraction intensity I (100') of the (100) plane, that is, the R value defined as I (002)/I (100) is in the range of 0≦R≦3. By forming an alumite underlayer on a magnetic recording medium and a substrate, and then forming a magnetic film layer of a Co-Ni base alloy containing Ru on this underlayer by sputtering, the magnetic film ( 002) plane X-ray diffraction intensity I
X-ray diffraction intensity I (002) and (100) plane
The gist of the present invention is a method of manufacturing a magnetic recording medium, characterized in that the R value, which is the ratio of

The present invention will be explained in more detail below.

The material of the substrate used in the magnetic recording medium of the present invention is aluminum or aluminum as a main component, and other metal elements are added to this to improve one or more of the properties such as strength, rigidity, and corrosion resistance. It is preferable that the properties are improved, for example, several weight percent of magnesium,
For example, one containing 3 to 4% by weight is used. Note that since silicon tends to precipitate as silicon dioxide, it is preferable to use a material with a low silicon content.

The base layer formed on this substrate is made of alumite. This underlayer is easily formed by oxidizing the surface of an aluminum or aluminum-based alloy substrate by anodization in an acid solution, but during this oxidation, metals other than aluminum contained in the substrate are oxidized. Therefore, the type and amount of metal oxides other than aluminum oxide in the coating are usually influenced by the type and content of metals other than aluminum in the substrate.

The thickness of this base layer is preferably 5 μm to 20 μm. If it is thinner than 5 μm, the strength against head collision is low, and there is a risk of so-called head crushing. On the other hand, if it is thicker than 20 μm, the internal thermal stress caused by temperature rises and falls during manufacturing becomes excessive, resulting in cracks. There is a risk of causing The base layer preferably has a Vickers hardness (1v) of 300 or more.

When l(v is smaller than 300, the impact strength becomes small.

The magnetic film layer formed on the underlayer is a CoNi-based alloy with a Ru content of 0.5 to 8 at% (00
2) X-ray diffraction intensity of plane 1 (002”) and (100)
The ratio of the surface X-ray diffraction intensity I (100'), that is, I
R defined as (002) / I (100”)
A value in the range of 0≦R≦3 is used. This magnetic film layer will be explained below.

(a) The composition of this magnetic film layer includes Ru and 1 Co.
It is preferable that 5 atomic % or less is substituted with Ni. In general, when a Go-Ni-Ru alloy magnetic thin film is manufactured by oblique incidence evaporation, its coercive force Hc reaches its maximum at 0.5 to 5 atomic %, and its corrosion resistance is also improved (for example, Although corrosion resistance is good in the sputtering method, a sufficiently high Hc value cannot be obtained and the requirements for a high-density magnetic recording medium are not met.

That is, the range of Hc required for a magnetic thin film is 5000e or more, and therefore, in a magnetic recording medium having a Co-Ni-Ru alloy magnetic thin film, the Ru content is usually set at 2 atomic %.
It is preferable to set it before and after. Note that the Ru content is 0
．． If the content is less than 5 at %, the magnetic properties are sufficient, but the corrosion resistance becomes poor. Moreover, when the Ru content is 8 at% or more, H
c and 4πMs are decreased, and the requirements for a high-density magnetic recording medium are not met.

Further, in the present invention, a part of cobalt is replaced with nickel. The addition of nickel causes a slight change in Hc, which has the effect of making it easier to adjust Hc according to the characteristics required for the medium. When replacing a portion of cobalt with nickel, the upper limit of this replacement ratio is preferably 15 atomic %. The reason for this is as follows. That is, if the substitution ratio by nickel exceeds 15 atomic %, the saturation magnetic flux density Bs decreases, and the crystal system changes from hcp to fcc, resulting in a decrease in the in-plane squareness ratio S. Ni is C, o-
It is most preferable to include 1 to 15 atom % of Ni-Ru.

(b) Magnetic properties are further improved by using crystal grains with a grain size of 100 to 500 as the main component.

That is, when the main grain size becomes smaller than 100, H
c becomes small and high-density recording becomes impossible. Particularly preferred is 200 to 400 people, resulting in a magnetic film layer with high Hc and low noise. In the present invention, the term "mainly" means that 50% or more of the particles fall within the particle size range, and the particle size is measured by observing with an electron microscope.

(c) R value, i.e. I (002) / I (100
) is set to 0≦R≦3, it is possible to increase the self-recording homogeneity of the film surface of the easy axis of magnetization (C axis). That is, when the present inventors investigated the C-axis direction of various Co-Ni-Ru films formed on a substrate, there was a very close relationship between the R value and the C-axis orientation. When R=O, the C-axis is completely oriented in the in-plane direction, and when R=3, the distribution in the C-axis direction is completely random and shows no orientation at all, 0≦
In the range of R4-3, the number of particles with the C-axis in the in-plane direction is larger, and in the range of R>3, the number of particles with the C-axis in the direction perpendicular to the film surface is larger ( It was recognized that by setting 0:5R≦3, the in-plane orientation of the easy axis of magnetization is maintained, resulting in an excellent magnetic recording medium.Even when R=3, it is not oriented in the perpendicular direction. Therefore, it can be adopted in the present invention.

Figure 1 shows Co-N i − sputtered in N2+Ar.
An example of an X-ray diffraction chart of a Ru magnetic film after heat treatment in vacuum at 350° C. for 3 hours is shown. In FIG. 1, R≧0.15, and the in-plane orientation of the C-axis is improved by the heat treatment.

(d) Hc can be increased by controlling the N and O contents to be each 1 atomic % or less. The magnetic recording medium of the present invention is produced by forming an alumite underlayer on a substrate as described later, and further forming a Co-Ni-Ru film thereon in an atmosphere containing N and/or O. However, in this heat treatment process, N and O are released and grain growth occurs. And the remaining N and O are each 1
By performing heat treatment to reduce the particle size to atomic percent or less, a magnetic film layer with good magnetic properties and grains grown to a predetermined grain size is formed.

As for N and 0, it is desirable to perform sufficient heat treatment to remove N and/or O so that both CoN and Coo are not detected by X-rays.

The magnetic recording medium of the present invention can be manufactured, for example, as follows. That is, an aluminum or aluminum-based alloy substrate is anodized in a mixed solution containing an acid such as chromic acid,
Form an alumite layer on the substrate surface. Then A containing N2
Co by a method such as sputtering in an r gas atmosphere
A -Ni-Ru alloy thin film is formed on a substrate and then heat-treated to release N. In this manufacturing method, the N content in the thin film first formed on the substrate is 3 atomic % or more,
For example, it is preferably 4 to 50 atomic %.

In this way, when a large amount of Nt is contained in a thin film during sputtering, a thin film consisting of an amorphous or microcrystalline substance with a grain size of about 50 to 150 grains is formed, and this thin film is crystallized or changed in grain size by heat treatment in the post-process. The grains grow to about 100 to 500 grains, forming a magnetic recording medium having an appropriate Hc and a high squareness ratio.

The temperature of this heat treatment is preferably about 300 to 600°C. If the temperature of the heat treatment is lower than 300°C, the rate of de-Ning becomes low and the crystallization of the thin film tends to be insufficient. Furthermore, if the heat treatment temperature exceeds 600° C., de-Ning will proceed too quickly and the crystal grain size will increase, resulting in a decrease in Hc. Particularly preferable heat treatment conditions are holding at 320° C. to 450° C. for about 1 to 5 hours, and by doing so, it becomes possible to manufacture products with excellent magnetic properties at low cost.

The magnetic recording medium of the present invention could be manufactured in exactly the same manner even if 02 was used instead of N2. It was also recognized that a mixed gas of N2 and 02 may be used instead of N2.

As the substrate used in the present invention, various conventionally used non-magnetic substrates can be used, including the aforementioned aluminum or aluminum alloy substrates (for example, aluminum alloys with a few percent or less of Mg added or titanium alloys). In addition to alloy substrates), crystallized glass or ceramic substrates are also used.

In addition to the underlayer, various intermediate layers for increasing the adhesion strength of the magnetic thin film may be provided between the substrate and the magnetic thin film.

Further, a protective film of carbon, polysilicate, or the like may be provided on the magnetic thin film. Furthermore, a lubricant may be applied onto this protective film.

[Effect]

In the magnetic recording medium of the present invention, the R value of the magnetic film is 0≦R.
≦3, it is characterized by high in-plane orientation of the axis of easy magnetization. Moreover, it also has the effect of being able to achieve high-density recording.

Further, this magnetic film can be formed by sputtering on an alumite underlayer.

Unlike the nickel-phosphorous underlayer, this alumite underlayer does not become magnetized even at high temperatures, so it is possible to heat-treat it before, during or after sputtering to improve the adhesion of the film. Furthermore, the deposition rate of the film can be increased by increasing the substrate temperature during sputtering.

In addition, it is presumed that sputtering on the alumite base layer has an effect.

〔Example〕

Hereinafter, the present invention will be explained in detail using specific examples.

Although the embodiment described below uses a magnetron r, f, and sputtering device, it is of course possible to obtain the effects of the present invention by ion beam sputtering, etc., which can be said to be similar in terms of ion technology.

Example 1 was anodized in an acid bath containing chromic acid, an alumite base layer with a thickness of 8 to 17 μm was formed on the surface, and the surface was polished to a thickness of about 2 μm to make it flat.

Next, using a flat plate magnetron r, f, sputtering device,
A Go-Ni-Ru thin film containing N was formed on the underlayer under the following conditions.

Initial exhaust 6 x 10' Tor
rTotal atmospheric pressure (A r +N2) 6 to 20 t
N2 gas concentration in aTorr atmosphere (% of N2 partial pressure to total pressure) 35-75% input power
IKW Target composition Co-N1-Ru (match the composition of the target thin film.

For example, Co:Ni:Ru=88:10:2
(atomic ratio), a target containing 88 atomic % of Co, 5 atomic % of Ni, and 2 atomic % of Ru is used. ) pole spacing
108 +a+s thin film formation speed 100-30
0 people/+win film thickness 700 people After forming this film, a carbon protective film was immediately formed by sputtering for 500 people. After this film is formed, the wing is airborne for 320 minutes.
Heat treatment was performed at ~400° C. for 1 to 5 hours to crystallize or grow grains of the film and release nitrogen. CoN was not detected by X-ray in this sample.

The magnetic properties of this magnetic recording medium are shown in Table 1 along with conditions other than those mentioned above.

Comparative Example 1 A magnetic recording medium was manufactured using the thickness of the underlayer, the composition and concentration of the magnetic layer, the N2 gas concentration in the atmosphere during sputtering, the heat treatment conditions, etc. shown in Table 1. Other conditions are the same as in Example 1. Table 1 shows the measurement results of its characteristics.

From Table 1, it is recognized that all the materials according to the present invention have excellent magnetic properties.

Further, the electromagnetic conversion characteristics of the No. 5 magnetic recording medium were measured as follows.

Head used: Mn-Zn ferrite mini Winchester type (track width 16μm, 1 gap length 1.1μm, 1 gap depth 20μm, number of turns 14TX2) Flying hide:
0.34μm 1F frequency: 1.25 MHz2F frequency
: 2.5 MHz Disk rotation speed : 3600
rpm measurement point: R=3 from the center of the disc
Measured at part 00I11.

The reproduction output characteristics were as follows.

2F playback output E 2F: 0.42 mVpp resolution (R=30mm): 87% override
: -34dB The magnetic recording media shown in Table 1 were heated at 60°C and relative humidity 90%.
An environmental resistance test was conducted by exposing the sample to the atmosphere for two weeks. The magnetic properties after the test are shown in Table 2.

From Table 2, it is recognized that all the magnetic recording media according to the present invention have excellent corrosion resistance.

From the above, it was found that this magnetic recording medium has characteristics as a high-density recording medium.

〔Effect of the invention〕

As detailed above, the magnetic recording medium provided by the present invention has a magnetic film layer with an R value of 0≦R≦3, has a high in-plane angular expansion ratio, and has good corrosion resistance. It has the characteristics of a high-density recording medium and is highly practical.

According to the manufacturing method of the present invention, such an excellent magnetic recording medium can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is an X-ray diffraction diagram of the magnetic film. Ne--rpa 1985 Patent Application No. 65525 Name of the invention Relationship to the case of a person who amends a magnetic recording medium and its manufacturing method Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (5
08) Koji Matsuno, Representative of Hitachi Metals, Ltd.

Claims (6)

[Claims] (1) In a magnetic recording medium in which a magnetic film layer is formed on the plate surface of a disk-shaped substrate, the magnetic layer is CoN containing Ru.
It is an i-based alloy, and the X-ray diffraction intensity of the (002) plane I(00
2) and the X-ray diffraction intensity I(100) of the (100) plane, that is, the R value defined by I(002)/I(100) is in the range of 0≦R≦3. magnetic recording media. (2) Claim 1, characterized in that the substrate is made of aluminum or an aluminum alloy, an alumite underlayer is formed on the substrate, and the magnetic film layer is formed on the underlayer. Magnetic recording medium described in Section 1. (3) The magnetic recording medium according to claim 1 or 2, characterized in that a protective film is formed on the magnetic film layer. (4) Form an alumite base layer on the substrate, and then apply Ru-containing C on this base layer by sputtering.
By forming a magnetic film layer of oNi-based alloy, the X-ray diffraction intensity I(002) of the (002) plane of this magnetic film and (
R, which is the ratio to the X-ray diffraction intensity I(100) of the 100) plane
A method for manufacturing a magnetic recording medium, characterized in that the value is 0≦R≦3. (5) The method for manufacturing a magnetic recording medium according to claim 4, wherein the substrate is made of aluminum or an aluminum alloy, and an alumite underlayer is formed by anodizing the substrate. (6) Sputtering in a nitrogen-containing atmosphere to form a nitrogen-containing alloy film, followed by heat treatment to denitrify it to form a magnetic film layer.
5. A method for manufacturing a magnetic recording medium according to item 5.