JPS59119543A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic layer which excels in the magnetic characteristics, electromagnetic conversion characteristics and traveling durability respectively, by applying the metallic atom vapor deposition onto a nonmagnetic substrate at a specific incident angle to form a magnetic thin film of columnar grains containing Co, Ni and Cr and then exposing said thin film to a glow discharging atmosphere in an environment containing water and argon to obtain an oxide layer. CONSTITUTION:A magnetic thin film of a prescribed composition is formed on a substrate by a so-called oblique vapor deposition process. This magnetic thin film consists essentially of Co with Ni and/or Cr added when necessary. The weight precentage of Co/Ni is set at >=1.5 when Ni is incorporated; while the electromagnetic conversion characteristics, output, S/N and film strength are improved with contents of Cr. The weight percentage of Cr/Co or Cr/(Co+Ni) is set at 0.001-0.1 (more preferably at 0.005-0.05). The minimum value of incident angle is set at >=20 deg. for the vapor deposition material to the normal line of the substrate. The environment of glow discharge contains water and argon with its total pressure set at about 5X10-1X10<-2> Pa.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Background of the Invention Technical Field The present invention relates to a method for manufacturing a magnetic recording medium, particularly 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.

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

Then, if a large amount of oxygen gas is introduced into the atmosphere during oblique evaporation, and the surface of the columnar crystal is covered with an oxide layer (Japanese Patent Publication No. 56-23208, etc.), the electromagnetic conversion characteristics will improve. This improves running durability and provides more favorable results.

In such cases, in Co-Ni systems, increasing the amount of introduced oxygen and increasing the number of oxide layers improves running durability, but reduces coercive force, which is an important property for high-density recording media. . Therefore, in order to increase the amount of introduced oxygen and maintain the coercive force to a certain degree, 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 basic efficiency is drastically reduced and the method becomes economically unsatisfactory. Furthermore, the film density decreases, resulting in a lack of corrosion resistance.

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.

II. 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 properties such as coercive force, magnetic flux, and squareness ratio, high electromagnetic conversion characteristics, and high running durability. 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 has excellent properties, is economical in manufacturing, and has high corrosion resistance.

Such objects are achieved by the following first and second inventions.

The first invention provides a method for disposing a magnet on a non-magnetic substrate at an angle of 20° or more with respect to the normal to the main surface of the substrate.
Co is deposited by making metal atoms incident at an incident angle of ;
, or a magnetic thin film consisting of an aggregate of columnar crystal grains containing Co, Nt and/or Cr, and then this magnetic thin film is exposed to a glow discharge atmosphere in an environment containing water and argon to cause the formation of the magnetic thin film. A method for producing a magnetic recording medium, comprising forming an oxide layer on the surface of columnar crystal grains to form a magnetic layer.

In addition, the second invention provides a method for disposing a magnetic material on a non-magnetic substrate at an angle of 20° or more with respect to the normal to the main surface of the substrate.
Inject metal atoms at two incident angles and perform A deposition, C
A magnetic thin film consisting of an aggregate of columnar crystal grains containing Ol or CO and Ni and/or Cr is formed, and then this magnetic thin film is exposed to a glow discharge atmosphere in an environment containing water, oxygen, and argon, and the magnetic This method of manufacturing a magnetic recording medium is characterized in that an oxide layer is formed on the surface of a thin film of columnar crystal grains to form a magnetic layer.

■. 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.

That is, it may consist of Co alone;

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.

In such cases, Cr/Co or Cr/(Co
+N1) (7) Weight ratio is 0.001 to O.

l, more preferably 0.005 to 0.05.

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

V, Zr, Nb, Ta, Ti, Zn, Mo, W.

It may also contain Cu or the like.

A magnetic thin film made of such components is formed by an oblique vapor deposition method.

In this case, the minimum value of the angle of incidence of the leather-wearing material with respect to the normal to the substrate is 20'' or more.

When the incident angle is less than 20'', 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 pressure is about 510-100 Pa, and the vapor deposition distance is
The substrate transport direction, mask arrangement, etc. may be the same as known conditions.

By such an oblique vapor deposition method, a magnetic V consisting of an aggregate of columnar crystal grains mainly composed of CO as described in ``2'' is deposited on the substrate.
A J film is formed.

In this case, the thickness of the magnetic thin film is 0.05 to 0.5IL,
m, preferably 0.07 to 0.3 pLm.

The columnar crystal grains have a length spanning almost the entire thickness direction of the thin film, and the longitudinal direction thereof is inclined in the range of 10 to 706 degrees with respect to the normal to the main surface of the substrate. There is.

Moreover, the short axis of the crystal grain has a length of about 50 to 500A.

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, particularly one made of resin such as polyester or polyimide.

In addition, the thickness may be various, but especially 5.
~2, OJL m is preferred.

The RMS value of the surface roughness height of the back surface of the surface on which the magnetic thin film is formed is preferably 0.05 #Lm 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
It is exposed to a glow discharge in an atmosphere containing water and argon.

In this case, it is important to contain water, and even if glow discharge is performed in an environment consisting of oxygen and an inert gas such as argon, the desired effects of the present invention will not be achieved.

In the present invention, the glow discharge environment contains water and argon, and the total pressure is usually 5X10 to 1X.
It is estimated to be about 1O-2Pa.

Moreover, the content of water is about 1 to 50%.

In such cases, corrosion resistance can be further improved by containing oxygen in addition to water and argon.

When oxygen is contained in the environment as a third component, its content is usually 1 to 50%.

Note that the environment may contain neon, krypton, xenon, etc. in an amount of 50% or less.

Further, other conditions for glow discharge, input power, current, etc. may be within the range of known conditions.

The time of exposure to glow discharge is usually about 1 second to 10 hours.

Due to such glow discharge, an oxide layer is formed on the surface of the columnar crystal grains of the magnetic thin film.

It contains COI or Co and Nt and/or Cr, and the atomic ratio of 0/(Co or Co+Ni) is preferably 0.3 or less, particularly 0.05 to 0.2.
A magnetic layer having a thickness of preferably 0.05 to 0.5 pm, more preferably 0.07 to 0.37 tm is formed.

Note that, if necessary, various uppermost protective layers can be formed on the magnetic layer.

(2) Specific effects of the invention The magnetic recording medium according to the invention is useful as a medium for video, audio, etc.

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 I Using an alloy with a Co/Ni weight ratio of 4, 12
A magnetic thin film with a thickness of 0°21 Lm was formed on a polyethylene terephthalate (PET) film with a thickness of pLm by an oblique vapor deposition method.

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

In addition, the atmosphere is set to P = 2XIO-2Pa and Ar Ta.

The obtained magnetic thin film has a Co/N i = 4 (weight ratio), and has a columnar shape that is inclined at about 30° with respect to the normal to the main surface of the substrate and has a minor axis of 100 A and is grown over the entire thickness direction. It was an aggregate of crystal grains.

This sample was then exposed to 15% H2O, 85% Ar, a total pressure of 2 Pa, and 15% H2O.

AC60Hz in an environment of 0220% and Ar65%
, 500 V, , LA, a glow discharge was generated, and samples Al and A2 were obtained by exposing each sample to the atmosphere.

Auger spectroscopy and ESCA were performed on these samples At and A2, and the Co and O concentration profiles were taken in the depth direction. It was confirmed that it was in the form of a combination with the crystal grains and existed on the surface of the crystal grains.

On the other hand, an alloy of Co/N i = 4 and P
In an atmosphere of =2×10 Pa, P =3×10==2 Ar 02 Pa, oblique evaporation was performed under the same conditions as in Section 2 to form a magnetic layer with a thickness of 0.2 gm, and sample AO
obtained, cross-sectional photographs, Auger spectroscopy, ESCA
From the results, it was almost the same as samples AI and A2.

The magnetostatic properties of these samples AO, At2, and A2 were measured. Table 1 shows the coercive force Hc, magnetic flux 1Δφm per cm' at Hmax=50000e, and squareness ratio.
Shown below.

Also, leave it for 30 minutes at 60°C and 90% relative humidity, and
When the magnetic flux change Δφm per m' was measured and the corrosion resistance was evaluated, the results shown in Table 1 were obtained.

Table 1 Sample AI A2 After AO
Processing HO+Ar 820, +
02 + At -0'/(Go+1) 0.
05 0.1 0.05 (atomic ratio) He (Oe) 80Q 90Q
'60 (13-3 φm IOX 10 10X 10
8X 1O-3 (ea+u/cm') Square shape ratio 0.8 0.8
0.7 chu food 2
16mm φm (%) From the results shown in Table 1, the effects of the present invention are clear.

It was confirmed that both samples Al and A2 had low running friction and could sufficiently withstand practical running.

Example 2 Co/Ni/Cr=75/20/
Using alloy No. 5, oblique evaporation was performed at P = 2
A thick magnetic thin film was obtained.

Next, this magnetic thin film was coated with 30% B20 + 70% Ar (
Bl) and 20%B20/15%02/65%Ar(
In the environment of B2), AC60Hz, IKV, 0.
A glow discharge was generated at 5A, and the sample was exposed to the atmosphere.

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 35 degrees to the normal line and have grown over the entire thickness direction with a yυ diameter of 200A, and 0 is present on the surface. This was confirmed.

These results are shown in Table 2.

Table 2 Sample BI B2 post treatment
Science B20 +Ar B20
+02+ArO/(Co+Ni) 0.
1 0.2 (atomic ratio) Hc (Oe) 850 9
00φm θX 1O-39X 10
-”(emu/crn') Square ratio 0.9
0.9 chuu food quality lO
Δφm, C%) From the results shown in Table 2, the effects of the present invention are clear.

It was confirmed that both samples B1 and B2 had low running friction and were sufficiently durable for practical running.

Applicant Tokyo Denki Kagaku Kogyo Co., Ltd. Agent: Patent Attorney Yo Ishii -

Claims (1)

[Claims] ■ On a non-magnetic substrate, 20° to the normal to the main surface of the substrate.
Evaporation is performed by making metal atoms incident at the following angle of incidence,
A magnetic thin film consisting of an aggregate of columnar crystal grains containing COI or CO and Ni and/or Cr is formed, and then this magnetic thin film is exposed to a glow discharge atmosphere in an environment containing water and argon to form a magnetic g film. A method for manufacturing a magnetic recording medium, comprising forming an oxide layer on the surface of columnar crystal grains to form a magnetic layer. 2. The magnetic recording medium according to claim 1, wherein the magnetic layer contains Ni and the weight ratio of Co/Ni is 1.5 or more. 3. The magnetic layer contains Cr, Cr/(Co or Co+N
A method for producing a magnetic recording medium according to claim 1 or 2, wherein the weight ratio of i) is 0.001-0.1. 4. Production of a magnetic recording medium according to any one of claims 1 to 3, wherein the atomic ratio of O/(Co or Co+Ni) in the magnetic layer is 0.3 or less. 5. The magnetic recording medium according to any one of claims 1 to 4, wherein the i-type layer has a thickness of 0.05 to 0.5 ILm. 6. On a non-magnetic substrate, at an angle of 20° to the normal to the main surface of the substrate.
Evaporation is performed by making metal atoms incident at the following two incident angles,
A magnetic thin film consisting of an aggregate of columnar crystal grains containing COI or CO and Ni and/or Cr is formed, and then this magnetic thin film is exposed to a glow discharge atmosphere in an environment containing water, oxygen, and argon, and the magnetic thin film is 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. 7. The method for producing a magnetic recording medium according to claim 6, wherein the magnetic layer contains Ni and has a Co/Ni weight ratio of 1.5 or more. 8. The magnetic layer contains Cr, Cr/(Co or Co+N
1) Cy) A magnetic recording medium according to claim 6 or 7 having a weight ratio of o, oot-o, t-c'. 9. The atomic ratio of 0/(Co or Co+Ni) in the magnetic layer is 0.3 or less Claims: Items 6 to 8
10. The magnetic recording substrate according to any one of claims 6 to 9, wherein the magnetic recording substrate has a thickness of 0.05 to 0.5 μm. VIII of the magnetic recording medium described in .