JPS62143229A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the much higher coercive force in a perpendicular direction and to improve magnetic characteristics and properties by vacuum-forming the film of an underlying layer contg. Ti on a substrate and forming a magnetic layer having columnar crystals of 10-300nm average grain size on the underlying layer without exposing the underlying layer to a >=10Pa atmosphere after the formation thereof. CONSTITUTION:The Ti underlying film is first formed by a Ti vapor deposition source 5 on the substrate 1 which is let off from a winding roll 2 and is taken up on a take-up roll 3 in the mid-way thereof. The magnetic layer is thereafter continuously formed by a Co-Cr vapor deposition source 6 on the periphery of a can 4 in the same vacuum vessel. After the Ti underlying layer is formed in the above-mentioned manner, the magnetic layer is continuously formed without leaking and opening to the atmospheric pressure. The respectively equal pressures are maintained during the formation of the underlying layer and the formation of the magnetic layer and the atmosphere in this case must be maintained under 10Pa. The magnetic layer has usually columnar crystal structure and the average size of the crystals is 10-300nm, more preferably 20-200nm, further preferably 20-100nm.

Description

BACKGROUND OF THE INVENTION Technical Field The present invention relates to a method of manufacturing a magnetic recording medium. More specifically, a so-called perpendicular recording magnetic recording medium has an underlayer containing Ti on a substrate, and a thin magnetic layer having an axis of easy magnetization perpendicular to the film surface on this underlayer. The present invention relates to a manufacturing method.

Prior Art and its Problems In recent years, there has been a demand for higher density in magnetic recording media, and a perpendicular recording method has been proposed as a response to this demand. This perpendicular recording method requires a medium whose axis of easy magnetization lies in the direction perpendicular to the film surface.

Conventionally, such Co-Cr [
However, it is difficult to put this method into practical use due to problems such as deposition rate.

Also, JP-A-56-127934, JP-A-56-165
No. 931, JP-A-57-53828, JP-A-57-2
No. 10452, JP-A-58-9220, JP-A-58-
No. 139338, JP-A-58-148139, etc.,
Proposals have been made to produce a Co-cr-based perpendicularly magnetized film using an ion blating method.

However, in these conventional ion blating methods, it is necessary to introduce a certain amount of gas for ionization.
It is difficult to control gas introduction, which increases the pressure during vapor deposition and disrupts crystal orientation. Therefore, it is not possible to obtain a material with a very large coercive force.

Furthermore, it has been reported that a perpendicularly magnetized film can be fabricated using a vacuum evaporation method that is expected to have a high deposition rate (NaL
ional Technical Report Vo.
l.

28 No. 6 Dec-1982 P4-P14).

In this report, a heat-resistant polymer material is used as the substrate, and Co-Cr11Q is deposited at a substrate temperature of 30 to 350°C. As the substrate temperature increases, the vertical coercive force increases by +2, and it is said that a coercive force of 10,000 e or more can be obtained at a substrate temperature of 300° C. or more.

However, with such conventional techniques, it is difficult to form a Co--Cr perpendicular magnetization film with high coercive force on a film with poor heat resistance such as polyethylene terephthalate.

Incidentally, it is generally known that a thin film of Ti is used as an underlayer of a magnetic recording medium for the purpose of improving adhesive strength (Japanese Patent Publication No. 39-26907, etc.).

Then, as a Co-Cr perpendicular magnetic recording medium, such an underlayer is provided on a heat-resistant substrate such as polyimide,
A proposal to improve the crystal orientation of the Co-Cr magnetic layer (
JP-A-58-159225, JP-A No. 59-22236
Publication No. 59-22225, Publication No. 59-3362
8, etc.) and proposals to prevent curling of the medium (Japanese Patent Application Laid-open Nos. 59-75429, 59-77621, 59-119541, etc.).
However, these proposals do not improve the coercive force in the direction perpendicular to the film surface.

In addition, instead of the aforementioned heat-resistant substrate such as polyimide, polyethylene terephthalate (PET), which has relatively poor heat resistance, can be used.
) is used as a substrate, and a Ti underlayer is similarly provided thereon to prevent curling of the medium (Japanese Patent Laid-Open No. 59-2218
No. 28, No. 59-221829, etc.) have also been carried out. In this case as well, the coercive force in the direction perpendicular to the film surface is not improved as in the above case.

Therefore, by providing a Ti-containing underlayer, it is possible to maintain the excellent effects such as crystal orientation, adhesion, and curl prevention of the Co-Cr of the magnetic layer, while also maintaining the properties perpendicular to the film surface of the magnetic layer. In view of this situation, the present inventors have previously proposed that a high coercive force can be obtained by controlling the average crystal grain size of the magnetic layer on the Ti underlayer. There is.

The present invention attempts to improve this proposal to obtain an even higher coercive force.

(2) Purpose of the Invention An object of the present invention is to provide a method for manufacturing a magnetic recording medium having a Ti underlayer which has a higher perpendicular coercive force and exhibits good magnetic and physical properties.

■Disclosure of invention Such objects are achieved by the invention described below.

That is, in the present invention, a Ti-containing base layer is formed on a substrate in a vacuum, and columnar crystals with an average grain size of 10 to 300 nm are formed on this base layer without exposing it to an atmosphere of 10 Pa or more after film formation. The present invention provides a method for manufacturing a magnetic recording medium, which is characterized by forming a magnetic layer having the following characteristics.

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

There are no particular restrictions on the material of the substrate used in the present invention.
It may be made of various materials such as metal, resin, glass, and ceramics.

The metal may be, for example, aluminum, aluminum with an anodic oxide film, or aluminum with a nickel phosphorus film formed thereon.

Furthermore, various types of glass and ceramics are possible.

Suitable resin materials include, for example, polyesters such as polyethylene terephthalate (PET) and polyethylene 2.6 naphthalate. These materials have extremely good surface smoothness and uniformity when formed into a film, and are inexpensive.

Alternatively, it may be a heat-resistant resin.

Such heat-resistant resins include polyamides such as aromatic polyamides, polyimides such as aromatic polyamides, polyphenylene sulfide, polysulfone, wholly aromatic polyesters, polyether ether ketone (PEEK),
Polyether sulfone, polyetherimide, etc.

Polyamide is a general term for polymers having an amide bond -CONH-, and is classified into natural polyamides and synthetic polyamides, and the former includes natural polypeptides.

Synthetic polyamides are obtained by polycondensation of diamines and dicarboxylic acids (-CORCONHR') and +RC obtained by polycondensation of NH+ forms and lactam ring-opening polymerization or aminocarboxylic acids.
It is broadly classified into ONH+ type.

Aromatic polyamides are disclosed in Japanese Patent Publication Nos. 56-136826 and 59-45124. For example, polyimide is a general term for polymers that have imide bonds in their main chains. Basically, polyamic acid is made from dicarboxylic acid and diamine, and after molding, it is heated, dehydrated, and cyclized to form polyimide.

The general formula is It is indicated by. Here, R is a divalent group.

These polyamides and polyimides have excellent heat resistance as a characteristic of polymers.

Polyphenylene sulfide is a polymer with a +0-3 structure and has excellent heat resistance.

Polysulfone is a polymer having 0 sulfonyl bonds in its main chain, and aromatic boron S-resulfone in particular has excellent heat resistance.

for example, is an example.

A wholly aromatic polyester is a polyester having an aromatic skeleton, and examples thereof include a polymer having the structure of.

The structure of polyetheretherketone (PEEK) is as follows.

The structure of polyether sulfone is as follows.

n The structure of polyetherimide is as follows.

There are no restrictions on the shape, size, and thickness of the substrate made of these various materials, and it may be determined according to the intended use. For example, it may be in the form of a film, a disk, or the like.

When making a tape, a resin material is used, and usually 3 to 70
The thickness is preferably about 3 to 20 μm.

On such a substrate, a base layer containing Ti is formed.

The Ti content in the stratum is usually 100at:% or less,
It is 80aL% or more, more preferably 90aL% or more. If the Ti content of the underlayer is 80 at % or less, the effect of providing the underlayer will not be noticeable, and the medium will not have a high coercive force in the direction perpendicular to the film surface.

Such an underlayer is usually formed of Ti alone.
Alternatively, it is formed as a Ti alloy, or as a material containing Ti oxide and/or nitride. and,
The content of substances other than Ti is usually less than 20 aL% to 0, particularly 10 at% or less.

As a Ti alloy, the alloying element added to Ti is A.
1, Cr%Fe, Mn, Mo, V, etc., roughly C1
0, N, H, etc. can be added.

Examples of Ti oxides include Ti01Ti203,
Examples of Ti nitrides such as TiO2 include TiN.

In these, a part of the composition of the underlying layer usually exists as an oxide or a nitride.

Among these, it is particularly preferable to use a base layer consisting only of Ti or containing O and/or N in a fat % or less, especially 0.1 to fat %.

The total amount of 0 and/or N in such an underlying layer is f
When it exceeds at%, the coercive force of the medium in the direction perpendicular to the film surface decreases.

The content of O and N contained in the underlayer can be measured by elemental analysis methods such as Auger spectroscopy and ESCA.

Such a Ti-containing base layer is formed by various vacuum film forming methods such as vapor deposition, sputtering, and ion blasting.

In this case, the film forming conditions may be within a variety of commonly used ranges, such as a substrate temperature of 30 to 100° C. and an operating pressure of about 0.01 to 1 mPa.

In addition, in order to particularly reduce the content of O and N to below fat%, for example, the substrate is preheated to 160 to 220°C in vacuum on the film forming surface, and then the substrate temperature is maintained at about 80 to 100°C. It is effective to set the operating pressure to about 0°01 to 0.1 mPa.

The thickness of the base layer formed in this way is 11000n.
Below, 20 to 600 nm is particularly preferable. If the film thickness exceeds 11,000 nm, the rigidity of the medium increases, resulting in poor head touch and moreover, a tendency to generate noise. Then, the coercive force decreases.

Further, if the thickness is less than 20 nm, the effect of improving coercive force is low.

Note that the average grain size of the Ti underlayer is 10 to 3000 m,
More preferably 20-200nm, especially 20-100o
It is I11.

A magnetic layer having an axis of easy magnetization in a direction perpendicular to the film surface is provided on such an underlayer.

FIG. 1 shows an example of a manufacturing apparatus.

The example shown is when a long film-like substrate 1 is used, and the substrate 1 is rolled out from the original winding roll 2 and wound up by the winding roll 3. T by source 5 ('1.U in the diagram, -/- line heating)
i A base film is formed.

Thereafter, in the same vacuum chamber, a magnetic layer is continuously formed on the four circumferences of the can by a Co--Cr vapor deposition source 6 (in the figure, CO and Cr are heated separately with electron beams).

As described above, in the present invention, after forming the Ti underlayer, the magnetic layer is continuously formed without so-called leakage or atmospheric pressure release.

In this case, as shown in the illustrated example, approximately the same pressure is applied between forming the underlayer and forming the magnetic layer.
A different atmospheric pressure may be used if necessary. just,
This atmosphere must be maintained below 10 Pa, more preferably IPa.

By doing so, disturbance of the interface of the Ti underlayer is prevented, and magnetic properties such as coercive force are improved.

Furthermore, if the formation of the Ti'F layer and the magnetic layer are performed continuously in the same vacuum chamber, the pressure inside the chamber will be reduced due to Ti evaporation, the film formation properties of the magnetic layer will be good, and the magnetic properties will be improved. do.

The magnetic layer usually has a columnar crystal structure, and the average grain size of this crystal is 10 to 300 r+m, more preferably 20 to 200 r+m.
0m, more preferably 20 to 1100n.

If the average grain size is less than 10 nm, the coercive force in the direction perpendicular to one pattern will be low, and if it exceeds 300 nm, the coercive force will similarly be low, and grain boundary noise will increase, which is not preferred in practice.

The columnar crystals forming such a magnetic layer are oriented substantially perpendicular to the film surface.

The thickness of such a magnetic layer is 50 to 11000 m, more preferably 60 to 900 nm.

When the thickness of this magnetic layer is less than 50 mm, the strength decreases, and when it exceeds 1100 mm, head touch becomes poor and modulation noise becomes large.

Note that on the surface of the magnetic layer, a convex portion having a base corresponding to the grain size and having a height of about 10 to 100 r++++ is usually formed due to the crystal grains. These irregularities improve running performance, etc.

In the present invention, the average grain size of the columnar crystals, the film thickness of the magnetic layer, etc. can be usually observed and calculated using electron micrographs [scanning microscope (SEM) and transmission microscope (TEM)] of the surface and fracture surface. I can do it.

The composition of such a magnetic layer is Co-Cr.
, Co-V, Co-N1-P, C.

-P, Mn-B1. Mn-An-Ge, Nd-Fe, N
d = Co, Co-0, Mn-5b.

Mn-Cu-B1. Gd-Fe, Gd-Co, Pt-C
o, Tb-Co, Tb-Fe-Co, Gd-Fe-Co
, Tb-Fe-03, Gd-IG, Gd-Tb-Fe,
Gd-Tb-Fe-Co-B1. It may be Co--Fe204 or the like, but Co--Cr is preferable.

Co-Crv, in particular, has C as a film composition due to its magnetic properties.
It is preferable that r is impregnated by 15 to 25 aL%.

In addition to CO and Cr, N is added within a range of 5 wt% or less.
i, Fe, 0, etc. may be contained.

Such a magnetic layer is formed using a vapor deposition method.

In the vacuum evaporation method, the evaporation source is heated in a high vacuum of 10' Torr or less using an electron beam method, resistance heating method, etc. to melt and evaporate it, and the vapor is deposited as a thin film on the surface of the substrate, for example. It's a method. The kinetic energy obtained by the evaporated particles during this evaporation is 0.1 eV to 1 eV
That's about it.

For the vacuum evaporation method, various known apparatuses may be used, and conditions such as the distance between the hearth and the substrate and the film deposition rate may be appropriately determined. In particular, but not limited to, In the present invention, the substrate temperature is usually 150 to 300°C, generally about 150 to 220°C, when forming the magnetic layer.

If the temperature exceeds 300°C, the damage to the substrate will increase, which is unfavorable in terms of manufacturing.

However, depending on the thermal deformation temperature of the substrate, for example, in PET, 2
The temperature shall be below 00℃.

Note that if this temperature is lower than about 150°C, for example,
The desired average grain size cannot be obtained for the crystal grains constituting the magnetic layer, and the coercive force of the medium decreases, which is not desirable in practice.

Furthermore, the operating pressure during magnetic layer formation is 0.01 to 10
mPa, more preferably about 0.1 to 1 mPa.

Note that the substrate temperature during formation of the underlayer and magnetic layer may be controlled by various heaters or cans.

Furthermore, it is preferable that each of the EL F and other treatments of the substrate be performed on at least the magnetic layer formation side of the resin substrate surface described above.

Examples of such a surface treatment method include a plasma treatment method and a vacuum treatment method such as ion bombardment.

Various known top coat layers may be provided on the magnetic layer of the magnetic recording medium of the present invention. Further, a back coat layer may be provided on the back surface of the substrate, and a high magnetic permeability metal thin film such as permalloy or other various known intermediate layers may be provided between the magnetic layer and the substrate.

In this case, the intermediate layer may be placed on the Ti base layer depending on the case, but preferably the intermediate layer is provided below the F layer.

■Specific effects of the invention According to the present invention,! A medium having an extremely high coercive force in the direction perpendicular to the film surface of the fi layer can be obtained.

Furthermore, the crystal orientation and adhesiveness of the magnetic layer are good, and curling is less likely to occur.

Such magnetic recording media are effective for use in perpendicular magnetization type magnetic tapes, flexible disks, and the like.

■Specific embodiments of the invention Specific examples of the present invention are shown below.

[Example 1 Various media were produced using the apparatus shown in FIG.

Polyethylene terephthalate (PET) with a pJ of 15 μm
) Film substrate 1 was used.

Ti was used as the Ti evaporation source 5, and a Ti underlayer was deposited on the substrate l.

The operating pressure in the Ti evaporation part was 0.05 mPa, the substrate l was heated to 70°C with a heater, and the evaporation rate was 1.
The thickness of the Ti film is approximately 0 nm/sec, and the thickness of the Ti film is 2
The range was 0 to 500 nrn.

Next, the substrate was continuously run along a can at a temperature of 180° C., and a Co'-Cr (weight ratio 80/20) alloy (25 mm diameter pellet) was used as the magnetic layer deposition source 6.
This was evaporated using an EB gun with a 270° deflection to deposit a Co--Cr magnetic layer on the Ti underlayer.

At this time, a composition analysis was performed using a film thickness controller (not shown), and E was adjusted so that the Co/Cr ratio was 80/20.
Vapor deposition was performed by controlling the B gun.

The conditions in the vapor deposition section were a working pressure of about 0.2 mPa and a vapor deposition rate of about 200 IIl/SCC.

In this way, as shown in Table 1, samples were prepared by varying the thickness of the geological layer, the thickness of the Co--Cr magnetic layer, and the crystal grain size.

The compositional analysis of the stratum was performed using Auger analysis (Model 600 manufactured by Al-Hatkufufi).

Separately, for comparison, we obtained a sample without the Ti-doped stratum.

In addition, after forming the Ti underlayer, the vacuum chamber was once opened to the atmosphere, the substrate was reversely wound, the magnetic layer was formed in the same manner after re-evacuation, and the sample was changed to a pressure of 500 mPa after the opening to the atmosphere. I got it.

The thickness of the magnetic layer and the average grain size of the columnar crystals of each sample were calculated from electron micrographs [scanning microscope (SEM) and transmission microscope (TEM)] of the surface and fracture surface.

Furthermore, the characteristics shown below were investigated for the valley sample.

(1> On the coercive force Hc in the direction perpendicular to the film surface (Oe) ・For the sample cut out in a constant area, the vibrating sample magnetometer (v
sM), and the coercive force was measured with a maximum applied magnetic field of 10 KG.

These results are shown in Table 1.

In addition, when the composition of O and N in the underlayer of each sample was measured, it was found to be less than 1aL%.

From the results shown in Table 1, the effects of the present invention are clear.

Incidentally, results similar to those in Table L were also obtained when Ti contained A1 or the like in an amount of 1 OaL% or more.

Similar results were also obtained with other substrates.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining an apparatus used in the present invention. Explanation of symbols 1--Substrate, 5=Ti vapor deposition source, 6-=Co-Cr
Evaporation source applicant: TDC Co., Ltd. (“DoFIG, 1

Claims (1)

[Claims] A base layer containing Ti is deposited in vacuum on a substrate, and a magnetic layer having columnar crystals with an average grain size of 10 to 300 nm is formed on this base layer without exposing it to an atmosphere of 10 Pa or higher after film formation. A method for manufacturing a magnetic recording medium, characterized in that: