JPS61104317A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and sliding resistance by forming a protective film consisting of a material selected from the group of an alloy consisting essentially of Si, Ge and alloy consisting essentially of Ge on a thin ferromagnetic metallic film. CONSTITUTION:Ge is evaporated from a vapor deposition source 3 to form a Ge layer 10 on a polyimide film substrate 1 while said substrate 1 is heated by a heater 2 in a vacuum. A Co-Cr alloy is in succession evaporated from a vapor deposition source 4 to form a ferromagnetic film 11 consisting of Cr thereon. Ge is further evaporated from a vapor deposition source 5 to form protective layer 12 consisting of Ge thereon. The sliding resistance is thus improved by providing the layer 12 and particularly the effect of the improvement is made remarkable by executing continuously the formation of the film 11 and the layer 12 in the vacuum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the improvement of magnetic recording media, and particularly aims at improving corrosion resistance and head sliding resistance.

[Background of the invention]

In response to the increasing demand for high-density recording in recent years, vacuum deposition,
The recording medium is a ferromagnetic metal thin film formed by sputtering or ion blating.

So-called binder-free magnetic recording media that do not use a binder have been attracting attention, and efforts are being made to put them into practical use. In addition to improving the magnetic properties of this type of magnetic recording medium, important issues to be solved for practical use include preventing deterioration of the medium due to oxidation, etc., and improving sliding resistance, which is the strength against contact with the head. There is.

A method for forming a protective layer for the purpose of preventing deterioration of the medium and improving its sliding resistance is to use thin ferromagnetic metal for magnetic recording media.
Method for oxidizing the surface of a film (Special Publication No. 1973-20025)
A method of nitriding (Japanese Unexamined Patent Publication No. 14311/1983) is known. However, there are problems in that it is difficult to control the thickness of the oxide layer or nitride layer, and the magnetic properties of the ferromagnetic metal film change due to oxidation or nitridation.

In addition, as a protective layer, an oxidation-resistant metal 1 such as Rh, Au, etc.
, Pt, Pd, Cr, AQ, Pd-B, GeS n ,
Method using A g -Cu etc. (Japanese Unexamined Patent Publication No. 53-40
505. JP-A-55-73932), method using silicon oxide film (JP-A-52-127203, JP-A-50-80102, U.S. Patent 3,
109,746. U.S. Pat.
-143114) is known.

However, although the above-mentioned metal protective film has contact resistance, it is still not sufficient in terms of sliding resistance, and the method using silicon oxide shows some improvement in sliding resistance, but it is not electrically insulating. Therefore, there is a problem in that it is difficult to sufficiently remove static electricity generated during operation of a magnetic recording system. Furthermore, films mainly composed of organic substances have the problem of static electricity and the tendency for dust to adhere to them.

[Purpose of the invention]

An object of the present invention is to provide a magnetic recording medium on which a protective layer is formed that has better contact resistance and abrasion resistance than conventional protective layers.

[Summary of the invention]

That is, in the present invention, after forming a ferromagnetic metal thin film on a substrate by a paper deposition method such as vapor deposition method, sputtering method, or ion blating method, it is continuously coated with an alloy mainly composed of Si, Ge or The present invention provides a method for manufacturing a magnetic recording medium with excellent corrosion resistance and abrasion resistance by forming a protective layer made of an alloy containing Ge as a main component by a paper deposition method.

The reason why the protective layer is formed continuously after the formation of the ferromagnetic metal film is as follows. If left unattended, oil vapor, water vapor, etc. will adsorb onto its surface, causing oxidation and contamination. If a protective film is formed on top of this, the bonding force between the protective film and the ferromagnetic metal film will decrease due to the effects of these oxide layers and adsorbed substances, making it impossible to obtain good sliding resistance. When a protective film made of an alloy containing Si as a main component, Go or Ge as a main component is formed immediately after the film is formed, the protective film material is deposited on the surface of the ferromagnetic metal film in a clean and active state. Therefore, the bonding strength between the two is increased, and the sliding resistance is also improved. In addition, if a protective film is formed continuously after forming a ferromagnetic metal film without exposing it to the atmosphere,
The formation of an oxide layer at the interface of the ferromagnetic metal film can be prevented, and as a result, the bonding strength between the two films is increased, and the sliding and contact resistance can be improved. In this case, it is desirable to continue heating the substrate until the formation of the protective film is completed. This is because heating can prevent adsorption of residual gas present in the thin film forming chamber of the paper deposition apparatus.

The thickness of the protective film is 0.003 to 0.3 μm, depending on the following conditions: that a sufficient protective effect is obtained, and that the magnetic recording and reproducing output is not reduced due to spacing loss due to the gap between the magnetic recording layer surface and the magnetic head. Preferably 0.1-0
．． A range of 15 μm is preferable.

As the protective film material, alloys mainly composed of Si, Ge and alloys mainly composed of Ge are preferable.

This is because it is easy to form a thin film, has a dense film, high hardness, excellent wear resistance, and has a large chemical affinity with ferromagnetic metals, resulting in high bonding strength. Furthermore, alloys mainly composed of Si e G6# alloys mainly composed of Ge have excellent corrosion resistance, and when using organic material-based lubricants for the purpose of further improving sliding resistance, Ge (
SL) e Sny CgSb, Bi, B, etc. may be added within the range (<50at%) that does not impair the above features.
Further, although it is preferable that the alloy Ge whose main component is Si and the alloy whose main component is Go are amorphous because it is easier to obtain a homogeneous film, they may contain crystalline materials. The substrate temperature when forming a protective film made of Ge containing Si as a main component or an alloy containing Ge as a main component is within a range of 50°C to 50°C, which is a range that maintains high bonding strength and does not deteriorate the magnetic properties of the ferromagnetic metal film. The temperature is preferably 400°C.

The ferromagnetic metal film according to the present invention is Co-Cr.

Go-V, Go-Mo, Go-W, G
o -Re, Co -0, Co -Cr -Rh,
Go -Cr -Ru, Go -Ni -0, co-
Ni, co-P, C0-B, C0-8i.

Go-Y, Go-La, Go-Pr, C
o-ce, Go-8m, Co-Mn, Co-N1
-P, Go-Ni-Cu.

Go-Ni-Hg, Go-Ni-W, Go-Ni-Re
.

C such as Go-Mn-P and Go-Zn-P
O-based alloy film.

Fe-Co, Fe-Ni, Fe-8i, Fe-Rh, F
Evaporation method or sputtering method for Fe alloy film such as e-V.

This corresponds to one formed by a paper deposition method such as an ion blating method. The thickness of the ferromagnetic metal film is 0.0
The film thickness is 3 to 5 μm, and in order to realize high-density magnetic recording, a film of 0.05 to 1 μm is more desirable.

Substrate materials forming the ferromagnetic metal film include polymer materials such as polyimide, polycarbonate, polyvinylidene chloride, polyethylene terephthalate, polyethylene naphthalate, cellulose acetate, polyamide, aluminum, and stainless steel copper.

A metal material such as brass, glass, or ceramic can be used. Furthermore, a thin film layer made of other materials may be provided between the substrate made of these materials and the ferromagnetic metal film.The shape of the substrate may be disk, tape,
Any drum is fine.

[Embodiments of the invention]

The present invention will be explained below using examples.

Example 1 A magnetic recording medium was manufactured using a vapor deposition apparatus having the configuration shown in FIG. 1 using a polyimide film as a substrate. lX
l0 - Polyimide film substrate l in a vacuum of Torr
While heating the substrate to 200° C. with an infrared heater 2, Qe was evaporated from the evaporation source 3 to form a 300-layer Ge layer on the substrate. Next, go from the evaporation source 4 at a substrate temperature of 150°C.
-Co-21w with a film thickness of 3500λ by evaporating the Cr alloy
t.

%Cr ferromagnetic metal film was formed. Further, Ge was evaporated from the evaporation source 5 at the same substrate temperature to obtain a film with a thickness of 200 g.
A protective layer consisting of O was formed, and a magnetic recording medium having the structure shown in FIG. 2 was produced. Here, 30
0 people attached Ge.

This is to improve the magnetic properties and increase the adhesion strength of the Go-Cr film.

Under similar conditions, Ge-3vt%C instead of Go protective layer,
Go-Lout%Si, Go-30vt%Sn,
A magnetic recording medium having a similar structure was fabricated using Ge25vt%Sb*Ge10ut%B. The samples produced under these manufacturing conditions are referred to as group A.

As a comparison sample, a thin film was formed under the same conditions as above, except that after forming a Co-Cr alloy film, the substrate temperature was lowered to room temperature, maintained for 10 hours, and then heated to 150°C to form a protective film. A set of magnetic recording media was manufactured. Samples produced under these manufacturing conditions are designated as Group B. As another comparison sample, after forming a Go-Cr alloy film, the substrate temperature was lowered to room temperature.

After opening the deposition apparatus and exposing it to air for 10 hours,
A set of magnetic recording media was manufactured in which a thin film was formed under the same conditions as in the first case, except that the protective film was formed at a substrate temperature of 150° C. under a vacuum of 0-” Torr. Under these manufacturing conditions. The prepared samples are group C.In addition,
Samples on which no protective film was formed were prepared as standard samples in each group A, B, and C.

Cut a disk sample from each sample thus obtained.
1, and a sliding resistance test was conducted using the following method. Set each sample disk on the disk rotation device and apply a load of 10g.
The disk was continuously rotated at a speed of 1.5 m/s by contacting the magnetic recording medium head, and the number of rotations until a scratch appeared on the magnetic recording medium thin film was measured. The results are shown in Table 1.

As is clear from the results in Table 1, the sliding resistance is significantly improved by providing the protective layer. In particular, the effect of improving the sliding resistance of Groups A and B, in which the ferromagnetic metal film and protective layer were formed successively in vacuum, was remarkable; The sliding resistance of the A group samples was particularly excellent.

In other words, in order to improve the sliding resistance, the first condition is to form the ferromagnetic metal film and the protective layer continuously without exposing them to air in between, and also to maintain the substrate temperature at a high temperature. A more desirable result can be obtained by continuously forming the Co-Cr alloy film and the G film described in this example.
Similar experiments were conducted to investigate the effect of the degree of vacuum on the combination of protective layers made of e or Ge alloy.
-' When the vacuum becomes worse than T orr, Co
It was observed that the bonding strength between the -Cr alloy film and the protective layer decreased, and the sliding resistance tended to deteriorate. In the above magnetic thin film, C
When Auger electron analysis was performed on the interface between the o --Cr alloy film and the protective layer, it was confirmed that an oxide layer was formed near the interface in the magnetic thin film produced in a bad vacuum. In addition, when we investigated the effect of the substrate temperature on the sliding resistance after forming the Co-Cr alloy film and starting to form the protective film, we found that when the lowest temperature of the substrate was less than 50℃, the surface was exposed to vacuum. easily adsorbed residual gas (and the sliding resistance deteriorated as well).

On the other hand, if the substrate temperature is too high, the quality of the polyimide substrate changes, so it was necessary to keep it at 400° C. or lower.

Here, G is used instead of the Co--Cr ferromagnetic metal film.

-V, Go-W, Co-Re, Go-Ni, Go-Cr
-Rh, Co-Cr-Ru, Co-8i, Co-Y, C
.

-La, Co-Pr, Go-Ce, Go-8m,
Go-Mn, Fe-Go, Fe-Ni, Fe
-5i, Fe-Rh.

A similar effect is also suggested when a Fe-V ferromagnetic metal film is used. After forming one ferromagnetic metal film, Ge
Alternatively, it has been found that the sliding resistance can be significantly improved by forming a protective layer made of an alloy containing Ge as a main component.

Example 2 A magnetic recording medium was fabricated using a continuous sputtering apparatus in the following procedure using an AQ disk having an alumite surface and having a diameter of 100 m and a thickness of 2 wn as a substrate. After evacuating the sample chamber of the continuous sputtering device to 5X10-' Torr,
Introducing Ar gas at X10-” Torr, high frequency output 4
W/c11. Go-80wt under the condition of substrate temperature 100℃
% Zr-9, 5 wt % Mo alloy was sputter deposited to a thickness of 5000.

Then, the sputter target was Go-20, 2wt%C.
Replaced with r alloy. During this time, the sample chamber is 3X10-3T.
The Ar atmosphere in orr and the substrate temperature were maintained at 100°C. A Co--Cr alloy film was sputter-deposited by 2000 people under the same conditions. Furthermore, the sputter target is
The substrate temperature was set at 150° C., and 200-layer MM made of Ge was formed under the same sputtering conditions.

Ge-2vt%C instead of Ge sputter target,
Ge-15v7%B, Ge-15wt%Si, Ge-1
0wt;%Sn, Ge-40ut%Sb,
Magnetic recording media were produced under the same conditions as above except that sputter targets of Ge-5wt%Mn and Ge-3wlh%Cr were used. This sample group is designated as D group.

As a comparison sample, after forming a Go-Cr alloy film, the substrate temperature was lowered to room temperature and kept in an Ar atmosphere of 3 x 10-' Torr for 24 hours, and then the substrate was heated to 150 °C to form a protective film. A set of magnetic recording media was manufactured in which thin films were formed under similar conditions. These samples are designated as Group E.

As another comparison sample, after forming the Go-Cr alloy film, the substrate temperature was lowered to room temperature, removed from the apparatus, placed in another sputtering apparatus, and evacuated to 6X10-' Torr.
A thin film was formed under the same conditions as described at the beginning of this example except that an Ar gas of XlO-'Torr was introduced and a 200λ protective layer made of Ge and a series of Ge alloys was formed under conditions of 5 W/ci. A set of magnetic recording media was fabricated. These sample groups will be referred to as F group.

In addition, there was a sample E with no protective layer formed.

When preparing samples for each group of F, one sample was prepared. The thus obtained sample was subjected to a sliding resistance test under the same conditions as in Example 1. The results are shown in Table 2.

As is clear from the results in Table 2, it was found that the sliding resistance was significantly improved by providing a protective layer made of Ge or a Ge alloy. In particular, the effect of improving the sliding resistance of the samples in Group D, in which the ferromagnetic metal film and protective layer were formed successively, was remarkable.Group D, in which the films were formed continuously while maintaining the substrate temperature at a high temperature. It was found that the sliding resistance of the sample was particularly excellent.

When Auger electron analysis was performed on the interface between the ferromagnetic metal film and the protective layer in the samples of groups D, E, and F, it was found that D,
It was confirmed that an oxide layer and a carbonide adsorption layer were formed at the interface in the F group samples compared to the E group samples.

It can be interpreted that this is because by keeping the substrate temperature at a high temperature, impurities such as oil vapor in the sample chamber can be prevented from being adsorbed on the surface of the ferromagnetic metal film, and this increases the bonding strength between the protective layer and the ferromagnetic metal film. . However, when the substrate temperature exceeds 400° C., problems such as deterioration of the magnetic properties of the ferromagnetic metal film and reaction between the ferromagnetic metal film and the protective layer material occur. Therefore, it is necessary that the substrate temperature does not exceed 400°C.

Furthermore, similar effects were obtained when polyimide, polyethylene terephthalate, polycarbonate, polyvinylidene chloride, glass, or brass was used as the substrate instead of the AM substrate.

Also, Go-V instead of Co-Cr on the An substrate.

Co-Mo, Co-Re, Go-Cr-R
h, Go-Cr-Ru, Co'-Ni-0, Go-
Ni, Go-P, C.

-B, Go-Si, Co-Ni-P, G
o-Ni-B.

Go-Ni-Ag, Go-Ni-Nd, Go-Ni
-Ce+Co-Ni-Zn, Go-Ni-Cu, G
o-Ni-Hg.

Go-Ni-W, Go-Ni-Re, C
o -Mn-P.

Go-Zn-'P, Fe-Go, Fe-Ni, Fe-5
i.

Regardless of whether Fe-Rh or Fe-V alloy films are used, the sliding resistance can be greatly improved by attaching a protective layer made of Ge or Ge alloy in succession to the formation of the ferromagnetic metal film. The effect was recognized.

In addition, all of the protective layers were recognized to be amorphous by X-ray diffraction.

Example 3 A magnetic recording medium using Si as a protective film was produced under the same conditions as in Example 1, except that 81 was evaporated from the evaporation source 5 instead of Ge in Example 1. Also.

As in Example 1, 5i-3wt% was used instead of the Si protective layer.
C, Si-10wt%Get si-30wt,%S
n, 5i-25vt%Sb, Si-10wt%B
A magnetic recording medium with a similar structure was fabricated using this method. Samples produced under these manufacturing conditions are designated as Group G.

As a comparative sample, a set of magnetic recording media was prepared in which thin films were formed under the same conditions as in Group B in Example 1. Samples produced under these manufacturing conditions are referred to as the tH group.

As another comparison sample, a set of magnetic recording media was prepared in which a thin film was formed under the same conditions as in the d group in Example 1. Samples produced under these manufacturing conditions are grouped as group (■).

In addition, samples with no protective film formed are shown in G and H.

A standard sample was prepared for each group in (2).

The same sliding resistance test as in Example 1 was conducted on each of the samples thus obtained. The results are shown in Table 3.

As is clear from the results in Table 3, as in Example 1, the sliding resistance is significantly improved by providing the protective layer.

In particular, the effect of improving the sliding resistance of Groups G and H, in which the ferromagnetic fully refractive thin film and the protective layer were formed successively in vacuum, was remarkable, and the film formation was performed continuously while maintaining the substrate temperature at a high temperature. The sliding resistance of the G group samples was particularly excellent. In addition, when the effect of the degree of vacuum on the combination of the Co-Cr alloy film and the protective layer made of Si or Si alloy described in this example was investigated by a similar experiment, it was found that when the vacuum becomes worse than 5XIO-'Torr, the Co-Cr
It was observed that the bonding strength between the alloy film and the protective layer decreased, and the sliding resistance tended to deteriorate. In the above magnetic thin film, Co-C
When Auger electron analysis was performed on the interface between the r-alloy film and the protective layer, it was confirmed that an oxide layer was formed near the interface in the magnetic thin film produced in a bad vacuum. Also, Co-C
When we investigated the effect of the substrate temperature on the sliding resistance between the formation of the r-alloy film and the start of the protective film formation, we found that when the lowest temperature of the substrate was below 50°C, residual gas in the vacuum formed on the surface. It was easily adsorbed, and the sliding resistance was also poor.

Furthermore, similar effects were observed when another ferromagnetic metal thin film was used in place of the Co--Cr ferromagnetic metal thin film as in Example 1.

Example 4 In Example 2, a Si sputter target was used instead of the Ge sputter target.

A magnetic recording medium using Si as a protective film was produced under the same conditions as in Example 2, except that the substrate temperature at that time was set at 100° C. and a 300-layer protective layer was formed.

5i-2vt%C instead of Si sputter target,
Si-15wt%B, Si=5wt%Qe, Si-10
wt%Sn, Si-4Qwt,%Sb, 5i-5
A magnetic recording medium was produced under the same conditions as above except that sputter targets of v7% Mn and Si-3wt% Cr were used. This sample group is designated as J group.

As a comparative sample, a set of magnetic recording media was prepared in which thin films were formed under the same conditions as in Group E in Example 2.

The thickness of the third layer is 300 people. Group these samples into groups.

As another comparative sample, a set of magnetic recording media was prepared in which thin films were formed under the same conditions as in Group F in Example 2. Note that the thickness of the protective layer is 300 people. These sample groups will be referred to as L group.

In addition, samples with no protective layer formed are J and K.

One sample was prepared for each group of L.

The thus obtained sample was subjected to a sliding resistance test under the same conditions as in Example 1. The results are shown in Table 4.

As is clear from the results in Table 4, as in Example 2, it was found that the sliding resistance was significantly improved by providing a protective layer made of Si or Si alloy. In particular, the effect of improving the sliding resistance of the J group samples in which the ferromagnetic metal thin film and the protective layer were successively formed was remarkable. It was found that the sliding resistance of the J group samples, in which films were continuously formed while keeping the substrate temperature at a high temperature, was particularly excellent.

Auger electron analysis was performed on the interface between the ferromagnetic metal film and the protective layer in the samples of each group J, L, and J.
It was confirmed that an oxide layer and a carbonide adsorption layer were formed at the interface in the L group samples compared to the L group samples.

Further, similar effects were obtained when other substrate materials were used instead of the AQ substrate as in Example 2.

Furthermore, even if another ferromagnetic metal thin film is used on the AQ substrate instead of Go-Cr in the same manner as in Example 2, a protective layer made of Si or Si alloy can be deposited continuously after the formation of the ferromagnetic metal thin film. Similarly, the effect of significantly improving the sliding resistance was observed.

Note that the protective layers were all recognized to be amorphous 1 by X-ray diffraction.

〔Effect of the invention〕

As is clear from the above explanation, after the formation of the ferromagnetic metal thin film, the alloy Ge or G containing Si as the main component is continuously used.
By forming a protective layer made of an alloy whose main component is e, it is possible to prevent the formation of an extra oxide layer at the interface between the ferromagnetic metal thin film and the protective layer, and as a result, the sliding resistance of the magnetic recording medium is improved. It can be improved. A similar improvement can also be achieved by sputter cleaning one surface of the ferromagnetic metal thin film to remove an excess oxide layer and then forming a protective layer. Further, by additionally applying a polymeric lubricant to the surface of the magnetic recording medium produced by the method according to the present invention, even more excellent sliding resistance can be obtained.

Alloys containing Si as a main component Ge and alloys containing Ge as a main component are chemically stable materials, and by providing a protective layer made of these materials, it is possible to improve the corrosion resistance of a magnetic recording medium. can.

According to the present invention, it is possible to simultaneously improve the corrosion resistance and the sliding resistance of a magnetic recording medium.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the preparation of a mounting device for carrying out the method of manufacturing a magnetic recording medium according to the present invention. FIG. 2 is an example of a cross-sectional structure of a magnetic recording medium manufactured according to the present invention. ■=Substrate, 2: Infrared heater, 3: Ge evaporation source, 4
: Co-Cr evaporation source, 5: Ge alloy or Si alloy evaporation source, 6: Substrate supply roll. 7: Board winding roll, 8 second guide roll. 9: Shiyahei plate, 10: Ge layer, 11: ferromagnetic metal film,
12: Protective layer.

Claims (1)

[Claims] 1. An alloy containing Si as a main component on a ferromagnetic metal thin film,
A magnetic recording medium comprising a protective film made of a material selected from the group of Ge and alloys containing Ge as a main component.