JPS61184725A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To enhance the orientation of the easy magnetization axis to the inside of the film surface by composing a magnetic film of a Co-base alloy contg. Ni and Pt and specifying the ratio of the X-ray diffraction intensity of the (002) face to the X-ray diffraction intensity of the (100) face in the specified range. CONSTITUTION:A substrate layer formed on a substrate consists of anodized aluminum. The substrate layer can be easily formed by anodizing the surface of the substrate of aluminum or an aluminum-base alloy in an acidic soln. The thickness of the substrate layer is preferably regulated to 5-20mum, and the substrate layer having >=300 Vickers hardness Hv is appropriately used. A Co-base alloy contg. Ni and Pt is used as the magnetic layer formed on the substrate layer, and the alloy whose ratio of the X-ray diffraction intensity of the (002) face to the X-ray diffraction intensity of the (100) face, namely the R value defined by I(002)/I(100), is regulated to 0<=R<=0.5 is used.

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. It relates to recording media and their manufacturing methods.

[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 magnetic disks used in external memory devices, and for this reason, research and development of magnetic recording media with alloy magnetic thin films with high recording density has been conducted in recent years. It is highly promoted.

One of them is cobalt (Co)-nickel (Ni)-
There is a method using a magnetic thin film of platinum (pH alloy) (Japanese Unexamined Patent Publication No. 59-61106), and it is known that Co-Ni-Pt alloy has corrosion resistance, and its thin film also has excellent corrosion resistance.

Incidentally, magnetic recording media generally include a hard underlayer provided on a substrate, a magnetic layer formed thereon, and a protective film further provided thereon, if desired.

In the case where a Co-N1-Pt alloy magnetic thin film is used as the magnetic layer, a nickel-phosphorus alloy (Ni
-P) is known to be used (JP-A-59-611
06).

[Problems to be Solved by the Invention] Although the Ni-P film conventionally used as an underlayer has a sufficiently high hardness, it becomes magnetized at temperatures of 200 to 250°C or higher, which increases noise. There is a problem in that the manufacturing conditions of the magnetic recording medium are subject to considerable restrictions.

On the other hand, CoNiP, which has been conventionally used as a magnetic layer,
Although it has been considered that t-alloy thin films can be used as in-plane magnetic recording media, the orientation of the axis of easy magnetization in the in-plane direction is still insufficient, and the magnetic properties are accordingly poor.

[Means for Solving the 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 plate surface of a disk-shaped substrate. is C containing Ni and Pt
It is an o-based alloy, and the X-ray diffraction intensity of the (002) plane and the (io
o) Ratio to the X-ray diffraction intensity of the plane, i.e., I (002)/
A magnetic recording medium characterized in that the R value defined by I (100) is in the range of 0≦R≦0.5, and an alumite base layer is formed on a substrate, and then this is formed by a sputtering method. By forming a magnetic film layer of a Co-based alloy containing Ni and pt on the underlayer, the X-ray diffraction intensity of the (002) plane and the X-ray diffraction intensity of the (100) plane of this magnetic film are
The gist of the present invention is a method for manufacturing a magnetic recording medium, characterized in that the R value, which is the ratio to the linear diffraction intensity, satisfies 0≦R≦0.5.

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 properties such as strength, rigidity, and corrosion resistance. Preferably, it contains magnesium in an amount of several percent by weight, for example, 3% by weight.
A substance containing up to 4% by weight is used. Note that silicon tends to precipitate as silicon dioxide, so a material with a low silicon content is preferable.

The base layer formed on this substrate is made of alumite a. This base layer 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. The resulting oxides become mixed in the underlying layer, and 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. Ru.

The thickness of this base layer is preferably 57 pm to 20 g, m
It is said that If it is thinner than 57 pm, the strength against head collision is small and there is a risk of so-called head crash. On the other hand, if it is thicker than 20 pm, the internal thermal stress caused by temperature rises and falls during manufacturing will become excessive. may cause cracks.

A base layer having a Vickers hardness Hv of 300 or more is preferably used. When Hv is smaller than 300, the impact strength becomes small.

The magnetic layer formed on the underlayer includes Nt and Pt.
The ratio of the X-ray diffraction intensity of the (002) plane to that of the (100) plane, that is, I (
R value defined by 002)/I (100) is 0≦R≦
A value in the range of 0.5 is used.

This magnetic film layer will be explained below.

(b) The composition of this magnetic thin film is 4 to 12 pt.
Preferably, Co contains 25 atom % or less of Co and is replaced with Nt.

In general, a Co-Pt alloy magnetic thin film has a property that its coercive force He becomes maximum at a Pt content of 20 atomic % (for example, Journal of the Japan Society of Applied Magnetics VO, 7, No. 2.
(1983), when containing about 20 atom % of Pt,
If Hc is too high, the override characteristics will deteriorate. That is,
The Hc range required for magnetic thin films is usually 500-1
000 (Oe), and therefore Co-Ni-P
In a magnetic recording medium having a t-alloy magnetic thin film, it is usually preferable to use a Pt content of around 10 atomic % and a Hc lower than the maximum value. In addition,
If the platinum content is less than 4 at %, corrosion resistance will be poor and Hc will be too low. A particularly preferred platinum content is 5 to 12 at.%.

Further, in the present invention, a part of cobalt is replaced with nickel. Adding nickel causes a slight change in Ha, which has the effect of making it easier to adjust Hc according to the characteristics required for the medium.

When a part of cobalt is replaced with nickel, the upper limit of the substitution ratio is preferably 25 atomic %.The reason for this is as follows. That is, the substitution ratio by nickel is 2.
This is because if it exceeds 5 atomic %, the saturation magnetic flux density Bs decreases, the crystal system changes from hcp to fcc, and the in-plane squareness ratio S decreases.

Ni is 21% tare to 15 atom% in Co-Ni-Pt
It is most preferable to include.

CI) Magnetic properties become even more excellent by mainly containing crystal grains with a grain size of 100 to 500 A. That is, when the main part of the crystal grains is smaller than 100A, He becomes small, while when it becomes larger than 500A, noise increases, making it unsuitable for high-density recording. Particularly preferred is 200 to 40 OA, which results in a magnetic film layer with high Hc and low noise.

In this specification, the term "mainly" means that 50% or more of the particles fall within the particle size range, and the particle size is measured by aS using an electron microscope.

(c) R value, i.e. I (002)/I (100), is set to 0.
By setting ≦R≦0.5, the film surface orientation of the easy axis of magnetization (C axis) can be improved.

That is, the present inventors have developed various Co--N films formed on a substrate.
When considering the C-axis direction of the i-Pt film, the above R
There is a very close relationship between the value and the orientation of the C axis,
At R;O, the C axis is completely oriented in the in-plane direction of the film, and R=3.
Then, the distribution in the C-axis direction is completely random and shows no orientation at all, and in the range of 0<R<3, the number of particles with the C-axis in the in-plane direction increases, and R In the range >3, it was observed that there were more particles with the C axis perpendicular to the film surface. By setting 0≦R≦0.5, the in-plane orientation of the axis of easy magnetization can be significantly improved.

Figure 1 shows Co-N1-Pt sputtered in N2+Ar.
An example of an X-ray diffraction chart of a magnetic film after heat treatment in vacuum at 350° C. for 3 hours is shown. In Figure 1, R-
0.1, and the in-plane orientation of the C-axis is improved by the heat treatment.

(d) Hc can be increased by making the content of N and 0 less than 1 atomic %. The magnetic recording medium of the present invention has an alumite film on the substrate as described below. After forming a base layer, a Co-Ni-Pt film containing N and/or O is formed on the base layer by sputtering in an atmosphere containing N and/or O, and this is heat-treated. However, in this heat treatment step, N and O are released and grain growth occurs. Then, heat treatment is performed so that the remaining N and O are each reduced to 1 atomic % or less.

A magnetic film layer with good magnetic properties is formed in which the grains have grown to a predetermined grain size.

Regarding N and 0, it is preferable to perform a sufficient heat treatment to remove N and/or 0 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 to form an alumite layer on the surface of the substrate, followed by a film formation method such as sputtering in an Ar gas atmosphere containing N2. A Co--Ni alloy thin film is formed on a substrate using the above method, and then heat-treated to release N.

In this manufacturing method, it is preferable that the content of N in the thin film first formed on the substrate is 20 atomic % or more, for example 40 to 50 atomic %.If a large amount of N is contained in the thin film during sputtering in this way, Amorphous or particle size 5
A thin film consisting of microcrystals of about 0A-150A is formed, and this thin film is crystallized or reduced in grain size to 100-150A by heat treatment in the post-process.
The grains grow to about 500A, form a magnetic recording medium having an appropriate amount of He 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,
When the heat treatment temperature exceeds 600°C, the de-N
progresses too quickly, and the crystal grain size increases, resulting in a decrease in the holding force Hc. Particularly preferable heat treatment conditions are 320-5
00°Cxo, shr ~3hr, and by doing so, it becomes possible to manufacture products with excellent magnetic properties at low cost.

According to research conducted by the present inventors, the magnetic recording medium of the present invention could be manufactured in exactly the same manner even if O2 was used instead of N2 during sputtering. 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, and the above-mentioned aluminum or aluminum-based alloy substrate (
For example, various types of glass or ceramic substrates can be used, as well as substrates made of alloys made of aluminum with Mg added in an amount of several percent or less or titanium alloys.

In addition to the underlayer, various intermediate layers that increase the adhesion strength of the magnetic thin film may be provided between the substrate and the magnetic thin film.
Further, a protective film made of carbon, polysilicate, etc. may be provided on the magnetic thin film, and a lubricant may also be applied onto this protective film.

[Function] In the magnetic recording medium of the present invention, the R value of the magnetic film is O≦
Since R≦0.5, the film is characterized by a high in-plane orientation of the axis of easy magnetization and a high squareness ratio of in-plane magnetism. Moreover, for this reason, the first effect of achieving high recording density is achieved.

Further, this magnetic film can be formed by sputtering on an alumite base layer. Unlike the nickel-phosphorous underlayer, this alumite underlayer does not become magnetized even at high temperatures. Therefore, it is possible to improve the adhesion of the film by applying heat treatment before, during or after sputtering. .

Furthermore, the sputtering speed can be increased by increasing the substrate temperature during sputtering.

Note that the reason why a magnetic film with high in-plane orientation can be formed by sputtering on an alumite underlayer is presumed to be due to the fact that this alumite layer is substantially amorphous.

[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 An aluminum alloy substrate containing 4% magnesium (size: 130 mm in diameter, 40 mm in inner diameter, 1.9 mm in thickness) was anodized in an acid bath containing chromic acid, and the surface was coated with a thickness of 8 mm.
An alumite base layer of ~17 pm was formed, and its surface was polished by approximately 24 m to make it flat.

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

Initial exhaust 1 to 2 x 10 Torr Total atmospheric pressure (Ar + N2) 15 to 30 mTorr N2 gas concentration in atmosphere (% of N2 partial pressure to total pressure) 35 to 75% input power
1kw target composition
Co-N1-Pt (to match the composition of the target thin film)For example, when forming a thin film with Co:Nt:Pt=80:10:10 (atomic % ratio), Co80 atomic %,
A target containing 10 atomic % of Ni and 1 atomic % of Pt is used. ) Pole spacing 108mm Thin film formation speed 100-300 A/m tn Film thickness 700A' After this film formation process, 320-400℃X1-I in vacuum
Lhr heat treatment was performed to crystallize or grow crystal grains in the film and to release nitrogen. From this magnetic film,
CoN was not detected by X-ray. Thereafter, a carbon protective film was formed by sputtering to a thickness of 50 OA to obtain a magnetic recording medium.

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 thickness 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 of the examples according to the present invention have excellent magnetic properties.

Further, the electromagnetic conversion characteristics of the magnetic recording medium No. 4 were measured as follows.

Head used: Mn-Zn ferrite mini Winchester (track width 16JLm, gap length 1,1
g, m, gi'r knob depth 20gm, number of turns 14T x 2
) Flyinder height: 0.34 tile m 1 F: 1, 25 MHz 2 F: 2.5 MHz Disc rotation speed: 360 Orpm Measurement location: Measured at R = 30 mm from the center of the disc The playback output characteristics are as follows. there were.

Reproduction output E2F=2.5 MHz: 0.42 mV Resolution (R-30 mm): 87% Override knee 34 dB From the above, it was found that this magnetic recording medium had characteristics as a high-density recording medium.

[Effect] As detailed above, the magnetic recording medium provided by the present invention has a magnetic film layer with an R value of O≦R≦0.5, has a high in-plane angular expansion ratio, and has a high It has the characteristics of a high-density recording medium and is highly practical.

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

[Brief explanation of the drawing]

FIG. 1 is an X-ray diffraction diagram of the magnetic film. Agent Patent Attorney Tsuyoshi Shigeno Procedural Amendment March 13, 1985 1 Indication of the case 1985 Patent Application No. 14655 2 Name of the invention Magnetic recording medium and its manufacturing method 3 Person making the amendment Relationship to the case Patent Applicant name (508) Hitachi Metals Co., Ltd. 4 Agent address 4-8-19 Akasaka, Minato-ku, Tokyo 107
Akasaka Omotemachi Building No. 502 No. 7 Contents of the amendment (1) On page 8, line 15 of the specification, the phrase ``this reason'' is corrected to ``r this reason''. (2) After "Used" on page 13, line 12, r.Also, a substrate in which a non-magnetic nickel-phosphorus base layer is formed on the substrate can also be used equally. ” to join. (3) Table 1 on page 18 of the same page is corrected as shown in the attached sheet. that's all

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 film is a Co-based alloy containing Ni and Pt, and the X-ray diffraction intensity of the (002) plane and (
100) plane to the X-ray diffraction intensity, i.e., I(002)
A magnetic recording medium characterized in that the R value defined by /I(100) is in the range of 0≦R≦0.5. (2) The magnetic recording medium according to claim 1, wherein an alumite underlayer is formed on the substrate, and the magnetic film layer is formed on the underlayer. (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) An alumite base layer is formed on the substrate, and then Ni and P are deposited on this base layer by sputtering.
By forming a magnetic film layer of a Co-based alloy containing t,
The X-ray diffraction intensity of the (002) plane of this magnetic film and the (100)
A method for manufacturing a magnetic recording medium, characterized in that the R value, which is the ratio to the X-ray diffraction intensity of the surface, is set to 0≦R≦0.5. (5) Claim 4, characterized in that the substrate is aluminum or an aluminum-based alloy, and an alumite base layer is formed by anodizing the substrate.
A method for manufacturing a magnetic recording medium according to paragraph 1. (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.