JPS59191138A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics such as coercive force, magnetic flux quantity and squareness ratio, an electromagnetic conversion characteristics, running durability and corrosion resistance by making metallic atoms incident to the surface of a base material at >=20 deg. angle to the normal thereof in performing vapor deposition. CONSTITUTION:A thin magnetic film having a prescribed compsn. is first formed on a base body by a diagonal vapor deposition method. The min. value of the incident angle of the material to be deposited by evaporation to the normal of the base body is made >=20 deg. in this case. The thin magnetic film consists essentially of Co and Ni and/or Cr is incorporated therein according to need. More specifically, said film may consist of Co alone or of Co and Ni. If Ni is incorporated therein, the weight ratio of Co/Ni is >=1.5. Cr may be further incorporated in the thin magnetic film. If Cr is incorporated therein, improvements in an electromagnetic conversion characteristics, output, S/N ratio and film strength are resulted. The weight ratio of Cr/Co or Cr/(Co+Ni) in this case is preferably 0.001-0.1, more preferably 0.005-0.05.

Description

DETAILED DESCRIPTION OF THE INVENTION I. BACKGROUND OF THE INVENTION 1. Technical Field The present invention relates to a magnetic recording medium, and particularly to a method for manufacturing a magnetic recording medium having a continuous thin film type magnetic layer by a so-called oblique evaporation method.

Prior art and its problems As magnetic recording media for video, audio, etc., media having a continuous thin film type magnetic layer are being actively developed because of their compactness when wound into tapes.

Due to its characteristics, the magnetic layer of such a continuous thin film type medium is made of Co-based, Co-Ni-based, etc. columnar crystals formed by the so-called oblique evaporation method, in which evaporation is performed at a predetermined angle with respect to the normal to the substrate. A vapor deposited film consisting of an aggregate of is suitable.

Then, when vapor deposition is performed by introducing a large amount of oxygen gas into the atmosphere during oblique vapor deposition, and the surface of the columnar crystal is covered with an oxide layer (Japanese Patent Publication No. 5.6-23208, etc.), electromagnetic conversion Properties are improved, running durability is improved, and more favorable results can be obtained.In such cases, in the Co-Ni system, increasing the amount of oxygen introduced and increasing the oxide layer improves running durability. However, the coercive force, which is an important property for high-density recording media, decreases. Therefore, in order to increase the amount of introduced oxygen and maintain the coercive force above a certain level, it is necessary to increase the angle of incidence with respect to the normal to the substrate during oblique deposition.

However, in such a case, the vapor deposition efficiency is drastically reduced and the method is economically unsatisfactory. Furthermore, the film density decreases, resulting in a lack of corrosion resistance.

Furthermore, the large amount of oxygen introduced causes problems such as oxidation of the molten metal in the crucible and problems with the vacuum system.

In other words, with the media produced by the conventional oblique vapor deposition method, it has not been possible to achieve a medium that satisfies all of the requirements of electromagnetic conversion characteristics, running durability, economical efficiency in manufacturing, and corrosion resistance.

■ Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and its main purpose is to provide high magnetic characteristics such as coercive force, magnetic flux, and squareness ratio, high electromagnetic conversion characteristics, It is an object of the present invention to provide a method for manufacturing a magnetic recording medium using an oblique vapor deposition method, which has a magnetic layer that is excellent in durability, economical in manufacturing, and has high corrosion resistance.

Such an object is achieved by the following invention.

In the present invention, metal atoms are incident on a non-magnetic substrate at an incident angle of 2oQ or more with respect to the normal to the main surface of the substrate to deposit Co1.
Alternatively, a magnetic thin film consisting of an aggregate of columnar crystal grains containing Co, Ni and/or Cr is formed, and then,
A magnetic recording medium characterized in that this magnetic thin film is exposed to an energetic particle flow consisting essentially of oxygen neutral particles to form an oxide layer on the surface of the columnar crystal grains of the magnetic thin film to form a magnetic layer. This is a manufacturing method.

Note that being substantially composed of oxygen-neutral particles means 50%
% or less of ionic particles or particles other than oxygen.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

In the present invention, first, a magnetic thin film having a predetermined composition is formed on a substrate by a so-called oblique evaporation method.

The magnetic thin film has Co as its main component, and Ni and/or Cr may be contained therein as required. 0, that is, it may consist of Co alone; c.

and Ni. If Ni is included, Co
/N i weight ratio is 1°5 or more.

Furthermore, the magnetic thin film may contain Cr.

When Cr is contained, electromagnetic conversion characteristics are improved, output and S/'N ratio are improved, and film strength is also improved.

Improves 0 In such cases, Cr/Co or Cr/(Co
The weight ratio of i) is 0.001 to 0.1, preferably 0.
．． It is preferable that it is 005-0.05.

Note that such a magnetic thin film may further contain other trace components, particularly transition elements such as Fe and Mn.

Vt Zr, Nb + Tar Ti + Zn
+Mo+W+Cu, etc. may be included. A magnetic thin film made of such components is formed by an oblique vapor deposition method.

In this case, the minimum value of the incident angle of the vapor deposition substance with respect to the normal to the substrate is 20° or more.

When the incident angle is less than 2O2, desired electromagnetic conversion characteristics cannot be obtained.

Note that there are no particular limitations on the vapor deposition conditions other than these.

That is, the vapor deposition atmosphere is an inert atmosphere such as argon, helium, vacuum, etc., as usual, and the deposition temperature is 10-5 to 100.
The pressure was approximately Pa, and the deposition distance, substrate conveyance direction,
The arrangement of the mask etc. may be the same as known conditions.

By such oblique vapor deposition method, the above-mentioned C is deposited on the substrate.
A magnetic thin film consisting of an aggregate of columnar crystal grains containing o as a main component is formed.

In this case, the thickness of the magnetic thin film is 0.05 to 0.5 μm, preferably 0.07 to 0.6 μm. , and its longitudinal direction is 1 with respect to the normal to the principal surface of 1 base.
It is inclined in the range of 0 to 70 degrees.

Further, the short axis of the crystal grains has a length of about 50 to 5008.

The substrate on which such a magnetic thin film is formed is not particularly limited as long as it is non-magnetic, and is preferably a flexible substrate, especially one made of resin such as polyester or polyimide. 0 The thickness may be various, but especially 5
It is preferable that it is 20 micrometers.

The RMS value of the surface roughness height of the back surface of the magnetic thin film forming surface is 0. ．． The thickness is preferably 0.05 μm or more.

This improves electromagnetic conversion characteristics.

Note that various underlayers may be interposed between the base and the magnetic thin film, if necessary.

After forming such a magnetic thin film, this magnetic thin film is
Exposure to energetic particles consisting essentially of oxygen-neutral particles.

In the present invention, the total pressure of the environment during exposure to the energetic particle flow is usually 5 x 10 to I x 10 -2 Pa or less.

Furthermore, the gas constituting the environment may be a normal inert gas, but is more preferably an oxidizing gas.

The energetic particle flow forms an oxide layer on the surface of the columnar crystal grains of the magnetic thin film.

and contains Co1 or Co and Ni and/or Cr, O/(Cot or C.

+N i ) preferably contains 0.3 or less, especially 0.05 to 0.2 O, preferably 0.05 to 0.2.
A magnetic layer is formed with a thickness of 0.5 .mu.m, preferably 0.07 to 0.6 .mu.m.

Incidentally, if necessary, various uppermost protective layers can be formed on such magnetic layer. Useful as a medium.

The medium according to the present invention has high magnetic properties such as coercive force, magnetic flux, and squareness ratio, and has high electromagnetic conversion properties.

In addition, running friction is low and running durability is high.

Furthermore, since the minimum value of the deposition incident angle can be kept at a low value, the deposition efficiency is high and the method is economical.

In addition, it has high corrosion resistance such as moisture resistance and oxidation resistance.

(2) Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in more detail.

Example 1 Using an alloy with a Co/N 1 weight ratio of 4, 12
A 0.2 μm thick magnetic thin film was formed on a μm thick polyethylene terephthalate (PET) film by an oblique vapor deposition method. Let this be A.

The film was continuously conveyed obliquely to the crucible, and the incident angle of the vapor-deposited substance was 40°.

The atmosphere was set to PAr-2xio 2pa. The magnetic thin film A obtained was Co/N1=4 (weight ratio) and had a short axis inclined at about 60° with respect to the normal to the main surface of the substrate. 1
It was an aggregate of columnar crystal grains of 00A that had grown over the entire thickness direction.

This sample A was then exposed to a neutral oxygen particle stream of 11-2 KeV produced using a neutral particle gun in an atmosphere with a total pressure of less than 10-5 Pa. Note that the beam amount of the particle flow is approximately 10 mA in terms of ion current.

The exposure time was 1 minute.
When sample A1 was subjected to Auger spectroscopy and ESCA, and the concentration profile of CO and O was taken in the depth direction, it was found that there was a lot of oxygen in the notation, and there was less oxygen inside, and that O was probably due to chemical shift. It was confirmed that Co/C was present on the surface of the crystal grains in the form of a bond with the metal.However, the surface of the magnetic layer was not destroyed and remained smooth. An alloy of N i = 4 is made of PA
r=2X10-2Pa+PO2=3X10'' Pa
Oblique vapor deposition was performed under the same conditions as above in an atmosphere of
A 0.2 μm thick magnetic layer was formed to obtain sample AO, which was found to be almost the same as sample A1 from the results of cross-sectional photographs, Auger spectroscopy, and ESCA.

The magnetostatic properties of these samples AO and AI were measured. Coercive force He, Hmax = 50000e, magnetic flux amount △fm1 and squareness ratio at 1.

are shown in Table 1.

In addition, it was left for 3 days at 60°C and 90% relative humidity, and 1c
When the change in magnetic flux Δfm of the rA heat was measured and the corrosion resistance was evaluated, the results shown in Table 1 were obtained (.

Table 1 Sample AI
Post-AD treatment Energy particle irradiation 0/(
Co+Nj, ) 0.05 0.
05 (atomic ratio) Hc (Oe) 750 600$m
9x103 8X10-3 (emu
/-f) Square ratio 0.8 0
．． 7 From the results shown in Table 1, the effects of the present invention are clear.

It was confirmed that sample A1 had low running friction and could sufficiently withstand practical running.

Comparative Example 1 Sample A was exposed to an oxygen ion particle stream under the same conditions as Example 1. As a result, the magnetic layer was so charged that no effective treatment could be carried out, and furthermore, the surface of the magnetic layer was destroyed and lost its smooth surface.

Example 2 Using an alloy of Co/Ni/Cr=75/2015, P
A 0.2 μm thick magnetic thin film was obtained on 12 μm PET by oblique vapor deposition at an incident angle of 45°.

The magnetic thin film was then exposed to a 1-2 KeV neutral oxygen particle stream created using a neutral particle gun in a 5 x 10'-2 Pa oxygen and water vapor atmosphere.

The beam amount of the particle stream is 20 mA in terms of ion current.

The exposure time was 5 minutes. This sample is designated as B1.

From these cross-sectional photographs, Auger spectroscopic analysis, and ESCA results, it is found that the particles are composed of columnar particles that are tilted at 65 degrees to the normal line and have grown over the entire thickness direction with a short axis of 200 A, and 0 is present on the surface. This was confirmed.

These results are shown in Table 2.

Table 2 Sample after B1
Processing Energy particle flow irradiation Hc (
Oe) 900$m
9X10' (emu/snow) Square shape ratio 0.9 resistance
Eating habits 2△j;m (%) From the results shown in Table 2, the effect of the present invention is clear○

Claims (1)

[Claims] 1. On a non-magnetic substrate, 2O2 with respect to the normal to the main surface of the substrate
Evaporation is performed by making metal atoms incident at the above angle of incidence, and 5c
A magnetic thin film consisting of an aggregate of columnar crystal grains containing Co and Ni and/or Cr is then formed, and this magnetic thin film is then exposed to an energetic particle stream consisting essentially of oxygen neutral particles to form a magnetic thin film. A method for manufacturing a magnetic recording medium, comprising forming an oxide layer on the surface of a thin film of columnar crystal grains to form a magnetic layer. 2. The magnetic layer contains Ni, and the Co/Ni weight ratio is 1.5.
The magnetic recording medium manufacturing method according to claim 1, which is the above. 6. The magnetic layer contains Cr, Cr/(Cot or CO+N
The method for manufacturing a magnetic LA recording medium according to claim 1 and claim 2, wherein the weight ratio of i) is 0.001 to 0.1. 4. 0/(Co or Co + Ni) in the magnetic layer
The magnetic recording medium manufacturing method according to any one of claims 1 to 3, wherein the atomic ratio of is 0.6 or less, and the thickness of the magnetic layer is 0.05 to 0.5 μm. A method for manufacturing a magnetic recording medium O as described in any one of claims 1 to 4.