JPH08337873A - Sputtering method - Google Patents

Abstract

PURPOSE: To provide a sputtering method which is capable of increasing the electric energy to be supplied and features excellent material use efficiency and mass productivity. CONSTITUTION: Magnetic poles (N pole and S pole) of a magnet 22 are moved relatively to each other in the sputtering method for forming thin films by installing this magnet 22 in the lower part of a target 21. For example, a center pole 22a (first magnetic pole) is arranged at the center of an annular magnetic pole (second magnetic pole). The second magnetic pole is fixed and the first magnetic pole is oscillated. The oscillation direction of the first magnetic pole is set at the traveling direction of a base body at the time when the base body is made to travel. This sputtering method is applied to, for example, the formation of the protective film of a metallic thin film type magnetic recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering method for forming various thin films, and more particularly to magnetic recording in which a magnetic thin film to be a magnetic layer is formed on a non-magnetic support by vacuum evaporation. The present invention relates to a sputtering method suitable for forming a protective film on a medium.

[0002]

2. Description of the Related Art Co-Ni alloys, Co-Cr alloys, Co
A metallic magnetic material such as -O is directly deposited on a non-magnetic support such as polyester, polyamide or polyimide film by plating or vacuum thin film forming means (vacuum deposition method, sputtering method, ion plating method, etc.), The metal magnetic thin film type magnetic recording medium is not only excellent in electromagnetic conversion characteristics at short wavelengths, but also remarkably small in thickness loss during recording demagnetization and reproduction, and the ratio of the magnetic material in the magnetic layer is extremely high (almost). It has many advantages such as 100%).

By the way, it is said that these metal magnetic thin film type magnetic recording media have problems in durability and rust resistance. Conventionally, investigation of organic materials such as lubricants and rust preventives by coating, A so-called undercoating technique has been studied in which fine particles are coated on a non-magnetic support in advance before forming a magnetic layer.

[0004] However, these techniques cannot fully support the use under a special environment and the harsh specifications for business use, and as a new method, vacuum deposition such as vacuum deposition, sputtering, plasma CVD, etc. A surface protective film has been studied by a thin film forming means.

[0005]

In such a situation,
The present inventors have succeeded in developing a magnetic recording medium excellent in durability and rust resistance by a protective film forming technique by the sputtering method, but the protective film forming by the sputtering method is inferior in mass productivity. It has become a challenge.

In the sputtering method, it is generally known that arranging a large number of cathode targets in the apparatus and increasing the amount of electric power supplied to each target greatly contributes to the improvement of the film formation rate. Therefore,
It is expected that mass productivity can be improved by adopting these methods, but the number of cathode targets that can be installed in a limited vacuum device is limited, and in that case, the input power amount of each target will be increased. How to increase the size is the key.

However, if the amount of input power is simply increased, the bonding agent such as indium or solder that adheres the cathode and the backing plate may melt due to the heat generated during sputtering, which may cause a short circuit of the electrodes. is there.

Further, generally, for the purpose of improving the film forming speed, magnetron sputtering is carried out in which a magnet is arranged below the target and the leakage magnetic field formed on the target surface by this is used. The so-called erosion problem occurs due to the distribution of the magnetic field on the target surface. Erosion is a phenomenon in which only a part of the target is significantly consumed, which causes a decrease in material use efficiency. In magnetron sputtering, by increasing the efficiency of use of this material, the interval between target replacements becomes longer, the length of film formation that can be made by one replacement becomes longer, and improvement in productivity can be expected.

Therefore, the object of the present invention is to provide a sputtering method capable of increasing the amount of input electric power and the material use efficiency and being excellent in mass productivity, whereby the reliability and the adhesiveness of the protective film and the stability are excellent. An object of the present invention is to make it possible to manufacture a magnetic recording medium with high productivity with high productivity.

[0010]

SUMMARY OF THE INVENTION The present invention relates to an improvement of the so-called magnetron sputtering method, in which a first magnetic pole having a predetermined polarity is provided under a target and a magnetic pole is disposed around the first magnetic pole. A magnet including a second magnetic pole having a polarity different from that of the first magnetic pole is installed, and it is large in that a thin film is formed on a substrate while moving the first magnetic pole and the second magnetic pole relatively. It has characteristics.

At this time, the magnet may be arranged by being divided into a plurality of blocks. In this case, in consideration of the simplicity of the moving mechanism of the magnet, downsizing of the whole cathode structure, etc. It is also possible to adopt a structure in which only a part of them moves relative to each other. Of course, it is possible to have a structure in which all of them can be moved relative to each other.

The present invention can also be applied to a sputtering method in which a thin film is formed on a traveling substrate, and in this case, the first magnetic pole is swung in the traveling direction of the substrate. By doing so, efficient sputtering is possible.

The present invention can be applied, for example, to the production of a magnetic recording medium, and is a magnetic recording medium in which a base body is formed by vacuum vapor deposition on a non-magnetic support to form a magnetic thin film, and the thin film to be formed is It is effective when it is a protective film.

A magnetic recording medium to which the sputtering method of the present invention is applied is a metal thin film type magnetic tape (so-called vapor deposition tape) in which a metal magnetic thin film is provided as a magnetic layer on a non-magnetic support made of a non-magnetic material. And is applied to the formation of a protective film on its surface.

In the magnetic recording medium, a magnetic metal material is formed as a magnetic layer by directly depositing a ferromagnetic metal material on a non-magnetic support. Any material may be used as long as it is used for a vapor deposition tape. For example, F
e, Co, Ni and other ferromagnetic metals, Fe-Co, Co-N
i, Fe-Co-Ni, Fe-Cu, Co-Cu, Co
-Au, Co-Pt, Mn-Bi, Mn-Al, Fe-
Cr, Co-Cr, Ni-Cr, Fe-Co-Cr, F
e-Co-Cr, Co-Ni-Cr, Fe-Co-Ni
A ferromagnetic alloy such as -Cr may be used.

These may be a single layer film or a multilayer film. Further, an underlayer or an intermediate layer may be provided for the purpose of improving the adhesive force between the non-magnetic support and the metal magnetic layer, or in the case of a multilayer film, and controlling the coercive force. Further, for example, the vicinity of the surface of the magnetic layer may be an oxide for improving rust resistance and the like.

As a means for forming the metal magnetic thin film, a vacuum vapor deposition method of heating and evaporating a ferromagnetic material under vacuum to deposit it on a non-magnetic support, or an ion plating method of evaporating a ferromagnetic metal material in a discharge. A so-called PVD technique such as a sputtering method in which atoms on the target surface are knocked out by argon ions generated by glow discharge in an atmosphere containing argon as a main component may be used.

A protective layer is formed on the magnetic layer made of the above ferromagnetic metal material by the sputtering method of the present invention. The material for this protective layer is known as a conventional protective film material for metal magnetic thin films. Any of the above can be used. For example, carbon, CrO ₂ , Al ₂ O ₃ ,
BN, Co oxide, MgO, SiO ₂ , Si ₃ O ₄ , Si
_{N x, SiC, SiN x -SiO} 2, ZrO 2, TiO 2,
TiC etc. are mentioned. These may be a single layer film or a multilayer film.

The structure of the magnetic recording medium (magnetic tape) to which the present invention is applied is not limited to this. For example, a back coat layer may be formed if necessary, or an undercoat may be formed on a non-magnetic support. There is no problem in forming a layer or forming a layer of a lubricant, an anticorrosive, or the like. In this case, as the material contained in the non-magnetic pigment, the resin binder, or the lubricant layer or the rust preventive layer contained in the back coat layer, any known material can be used.

Needless to say, the present invention is applicable not only to the formation of the protective film in the above magnetic recording medium but also to the formation of various thin films.

[0021]

In magnetron sputtering, when the magnetic poles of the magnet are moved relative to each other, the positions of the target to which heat is applied dispersively move, and as a result, the cooling efficiency increases. Therefore, the amount of input electric power can be increased and the film forming speed can be improved.

The movement of the magnet also disperses erosion and improves the efficiency of use of the target.

[0023]

EXAMPLES Specific examples to which the present invention is applied will be described below in detail with reference to the drawings and experimental results.

First, a metal magnetic thin film made of Co--Ni was formed as a magnetic layer on a polyethylene terephthalate (PET) base under the following conditions. At this time, the manufacturing apparatus used is a general continuous winding type oblique vapor deposition apparatus.

Metal magnetic thin film deposition conditions Base: Polyethylene terephthalate Thickness 10 μm 150 mm width Undercoat: Water-soluble latex containing acrylic ester as a main component Protrusion density 10 million pieces / mm ² Ingot: Co 80 wt% -Ni 20 wt% Incident Angle: 45 to 90 ° Tape speed: 0.17 m / sec Magnetic layer thickness: 0.2 μm Oxygen introduction amount: 3.3 × 10 ⁻⁶ m ³ / sec Vacuum degree during vapor deposition: 7 × 10 ⁻² Pa Back coat: A mixture of carbon and urethane binder is applied to a thickness of 0.6 μm. Top coat: Perfluoropolyether is applied Slit width: 8 mm width Next, a protective film was formed on the metal magnetic thin film by sputtering. The sputtering device used in the example will be described.

As shown in FIG. 1, in this sputtering apparatus, the inside of the vacuum chamber 1 is evacuated by the exhaust ports 15 provided at the head and the bottom, respectively.
A feed roll 3 that rotates at a constant speed in the clockwise direction in the figure and a winding roll 4 that also rotates at a constant speed in the clockwise direction in the figure are provided. The magnetic support 2 is sent out.

A large diameter cooling can 5 is provided midway between the feed roll 3 and the take-up roll 4. The non-magnetic support 2 is wound around the peripheral surface of the cooling can 5, so that the cooling can 5 is also rotated at a constant speed in synchronization with the rolls 3 and 4.

A cooling device (not shown) is provided inside the cooling can 5, and the non-magnetic support 2 is
It has a structure capable of suppressing deformation and the like due to the temperature rise.

Guide rolls 6 and 7 are arranged between the feed roll 3 and the cooling can 5 and between the cooling can 5 and the take-up roll 4, respectively. A predetermined tension is applied to the non-magnetic support body 2 which is run to the winding roll 4.

On the other hand, in the vacuum chamber 1, the cooling can 5
A cathode target 8 is provided at a lower position of, and a protective film material 9 is adhered to the surface of the cathode target 8 as a target.

In this example, the cooling can 5 is structured to be cooled, but it may be appropriately heated to improve the adhesion between the protective film and the magnetic layer.

The structure of the cathode target 8 will be described below. As shown in FIG. 2, the cathode target 8 is connected to a power source (not shown) and has a backing plate 23 having a function as a cathode electrode. A target 21 adhered to the magnet, a magnet 22 arranged on the back side of the backing plate 23,
And a cathode case 2 for housing these magnets 22
It consists of 5.

The surface of the backing plate 23 has a larger area than the target 21.
The area other than the area where 1 is arranged is covered with the cathode mask 26.

As shown in FIG. 3, the magnet 22 is composed of a center pole 22a having a predetermined length and a rectangular ring-shaped magnet ring 22b surrounding the center pole 22a. The magnet ring 22b and the magnet ring 22b have different polarities (for example, the center pole 22a is the N pole and the magnet ring 22b is the S pole).

The magnet ring 22b is fixed, and the center pole 22a swings in the direction of the arrow in the figure (corresponding to the running direction of the magnetic recording medium), whereby the magnetic poles move relative to each other and the magnetic field. The formation position moves on the target 21. Therefore,
The cathode target 8 has the center pole 22a.
A unit 24 for moving the same in the same plane is added.

Using the sputtering apparatus having the above structure,
A protective film was formed on a magnetic recording medium on which a Co—Ni alloy was obliquely deposited and a metal magnetic thin film was formed as a magnetic layer. The conditions for forming the protective film are as follows.

Protective film formation conditions Method: DC magnetron sputter target material: Carbon used gas: Argon Background vacuum degree: 4 × 10 ⁻³ Pa Vacuum degree during film formation: 2 Pa Tape feed speed: 0.1 m / sec to 0. 05 m / sec Protective film thickness: 0.015 μm After forming the protective film, a back coat and a top coat were applied and cut into a predetermined tape width to prepare a sample tape.

With respect to the obtained sample tape, still durability and weather resistance were measured. The still durability was measured by using a modified model EV-S900, manufactured by Sony Corporation, and the time from the initial level until the output of 3 dB was attenuated. Further, the weather resistance was measured using a gas corrosion tester, and the deterioration amount (Δs) of the magnetic properties (φs) after storage for 24 hours in an atmosphere containing SO ₂ gas of 0.3 ppm at a temperature of 30 ° C. and a relative humidity of 90%.
φs) was calculated by the following equation.

[0039]

[Equation 1]

As a measure of the effect of this example, the usage efficiency of the target material was measured as follows.

First, before the film formation, the weight of the target bonded on the backing plate is measured.
(Weight of Target + Backing Plate) Next, after the film formation, the weight of the target bonded on the backing plate is calculated in the same manner.

This difference is the amount of material actually consumed during film formation. In order to compare each Example and Comparative Example under the same conditions, each film formation was made 5000 m long, and Comparative Example 1
The weight consumed as 0% was compared and expressed as a relative value.

The results are shown in Table 1. In this embodiment, the movement of the magnet (center pole 22a) is
The movement was performed at a constant speed, and the movement distance was 2 cm in each of the front and rear.

[0044]

[Table 1]

Looking at Table 1, Comparative Example 1 and Example 1,
Although the input powers during film formation were the same between 2 and 3, the feed rate during film formation was reduced by about 10%. This is because the magnetic field distribution on the target surface changes due to the movement of the magnet, and the efficiency during sputtering decreases. However, as in Comparative Example 2, the input power is 7
If film formation is continued for a long time in the state of W, the bonding material that adheres the backing plate and the target will melt, and film formation will not be possible (for this reason, the material usage efficiency could not be measured).

On the other hand, in the fourth and subsequent embodiments, since the lower magnet moves, the position where heat is applied dispersively moves, and as a result, the cooling efficiency is improved. This allows
The target (bonding material) bonded to the backing plate will not lose heat, there is no need to reduce the feed rate during film formation, material usage efficiency will improve, and target productivity in one setup change will be significant. Improved.

Further, the film quality of the formed protective film is equivalent to that of the comparative example in view of the results of still durability and deterioration of magnetic properties (weathering resistance), and it is understood that the effect of the present invention is great.

Although the embodiment of the present invention has been described above by taking the formation of the protective film of the magnetic recording medium as an example, it goes without saying that the present invention is not limited to this embodiment.
For example, it can be applied to various thin film formations as well as the protective film of the magnetic recording medium. Also, when applied to a magnetic recording medium, the order and conditions of steps such as vapor deposition, sputtering, and back coating, materials used, etc. are arbitrary.

[0049]

As is apparent from the above description, according to the sputtering method of the present invention, it is possible to increase the amount of input electric power and to improve the material use efficiency of the target.

Therefore, when the present invention is applied to the formation of a protective film for a magnetic recording medium, the protective film has excellent adhesiveness and stability,
A magnetic recording medium having high reliability can be manufactured with high productivity.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of a sputtering apparatus.

FIG. 2 is a schematic cross-sectional view showing the structure of a cathode target.

FIG. 3 is a schematic plan view showing the shape of a magnet.

[Explanation of symbols]

 8 cathode target 21 target 22 magnet 22a center pole 22b magnet ring

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G11B 5/84 7303-5D G11B 5/84 B

Claims (3)

[Claims] 1. A magnet having a first magnetic pole having a predetermined polarity and a second magnetic pole having a polarity different from that of the first magnetic pole arranged around the first magnetic pole under the target. A sputtering method, which is characterized in that the thin film is formed on a substrate while the first magnetic pole and the second magnetic pole are moved relative to each other. 2. The sputtering method according to claim 1, wherein the first magnetic pole is swung in the traveling direction of the substrate while the substrate is traveling. 3. The sputtering according to claim 1, wherein the substrate is a magnetic recording medium in which a magnetic thin film is formed on a non-magnetic support by vacuum deposition, and the thin film formed is a protective film. Method.