JPH07220971A - Manufacture of amorphous magnetic thin film with uniaxial magnetic anisotropy - Google Patents

Abstract

PURPOSE:To provide a manufacturing method of an amorphous magnetic thin film with good uniaxial magnetic anisotropy all over a wide area. CONSTITUTION:In the manufacturing method of an amorphous magnetic thin film having uniaxial magnetic anisotropy, when an amorphous magnetic thin film is formed on a substrate by sputtering a target in gas atmosphere, an organic high polymer film wherein an absolute value of a difference alphaMD-alphaTD between heating contraction ratio alphaMD in a longitudinal direction and heating contraction ratio alphaTD in a width direction after heating treatment at 150 deg.C for 15 minutes is 0.003 to 0.015 is used as a substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an amorphous magnetic thin film having uniaxial magnetic anisotropy, which is suitable for improving the magnetic characteristics or uniformity of the amorphous magnetic thin film.

[0002]

2. Description of the Related Art Conventionally, in an amorphous magnetic thin film, in order to improve the magnetic characteristics or achieve uniformity, it is general to impart an appropriate amount of uniaxial magnetic anisotropy. As a method of imparting such uniaxial magnetic anisotropy, a method of forming a thin film in a magnetic field, a method of forming a magnetic material by vacuum deposition or a sputtering method, and at the same time an ion beam from an oblique direction with respect to the substrate surface. Irradiation method (JP-A-2-52415), method for forming a magnetic thin film on a substrate having anisotropy in thermal expansion coefficient (JP-A-5-82378), and other methods performed during thin film formation , Or
A method of performing heat treatment after forming a thin film (Japanese Patent Publication No. 2-133515) is known.

[0003]

However, in the method of forming a thin film in a magnetic field, it is difficult to apply a uniform magnetic field in a fixed direction over a wide area, and therefore, good uniaxial magnetic anisotropy is imparted. There was a problem that it was difficult. Further, although a method of irradiating the substrate with an ion beam from an oblique direction while forming a magnetic material by vacuum deposition or sputtering, a thin film having relatively good uniaxial magnetic anisotropy can be obtained, There is a problem in that it is difficult to produce an amorphous magnetic thin film because the substrate temperature rises by irradiating the substrate with. Further, there is a problem in that the irradiation conditions of the ion beam and the like must be accurately controlled, which results in high cost.

On the other hand, in the method of forming a magnetic thin film on a substrate having an anisotropy in the coefficient of thermal expansion, the reverse effect of the magnetostriction of the magnetic thin film is utilized to obtain a good uniaxial magnetic anisotropy in the direction of magnetization. It is possible to get the direction. However, when making an amorphous magnetic thin film by this method, in order to effectively utilize the thermal expansion coefficient, the substrate should be heated at 250 to 300 ° C.
Therefore, not only good uniaxial magnetic anisotropy cannot be obtained, but also the magnetic thin film is partially crystallized. Furthermore, it was difficult to impart good uniaxial magnetic anisotropy over a wide area with this method.

Further, the method of heat-treating after the thin film is formed is such that after the thin film is formed on a substrate having a small thermal expansion difference from the magnetic thin film, the thin film is fixed in a curved shape and heat-treated, and thereafter,
This is a method of imparting uniaxial magnetic anisotropy by restoring to a flat plate shape. However, such a method has a problem in that the process becomes complicated, and the uniaxial magnetic anisotropy varies depending on the fixed state when fixed in a curved shape. It is an object of the present invention to provide a method for producing an amorphous magnetic thin film having good uniaxial magnetic anisotropy over a wide area.

[0006]

The inventors of the present invention have made extensive studies as a result of solving the above problems, and as a result, when forming an amorphous magnetic thin film, heat shrinkage in a longitudinal direction and a width direction as a substrate. The present inventors have found the fact that an amorphous magnetic thin film having a good uniaxial magnetic anisotropy over a wide area can be produced by using an organic polymer film whose difference from the ratio is within a specific range, and arrived at the present invention. That is, the present invention, when forming the amorphous magnetic thin film on the substrate by sputtering the target in a gas atmosphere, as a substrate,
Difference between heat shrinkage ratio α _MD in the longitudinal direction and heat shrinkage ratio α _TD in the width direction after heat treatment at 150 ° C for 15 minutes α _MD
The gist is a method for producing an amorphous magnetic thin film having uniaxial magnetic anisotropy, which is characterized by using an organic polymer film having an absolute value of −α _TD of 0.003 to 0.015.

The present invention will be described in detail below. In the present invention, when the amorphous magnetic thin film is formed on the substrate by sputtering the target in a gas atmosphere,
As the substrate, the absolute value of the difference α _MD −α _TD between the heat shrinkage ratio α _MD in the longitudinal direction after heat treatment at 150 ° C. for 15 minutes and the heat shrinkage ratio α _TD in the width direction is 0.003 to 0.015. It is necessary to use a polymer film, α _MD
-The absolute value of α _TD is 0.005 to 0.01, and 0.006 to
It is preferable to use an organic polymer film having a thickness of 0.008.

When the absolute value of α _MD −α _TD exceeds 0.015,
The magnetic thin film becomes wrinkled and cannot be put to practical use. On the other hand, when the absolute value of α _MD −α _TD is less than 0.003, no effect is exhibited and it becomes impossible to obtain an amorphous magnetic thin film having good uniaxial magnetic anisotropy. Here, the longitudinal direction of the organic polymer film referred to in the present invention is a direction in which the organic polymer film is fed and wound up, and the width direction is a direction perpendicular to the longitudinal direction. .

Examples of the organic polymer film that can be used in the present invention include polyethylene terephthalate.
Polyester films such as (PET), 2,6-polyethylene naphthalate (PEN) and polyarylate (PAR), nylon films such as nylon 6, 66 and 12, polyphenylene sulfide film (PPS), polysulfone (PSF), poly Amorphous unstretched film such as ether sulfone (PES), polyimide film (PI), polypropylene film
(PP), wholly aromatic amide film (APA) and the like. In such various organic polymer films,
A film having various kinds of heat shrinkage can be manufactured depending on the difference in the film manufacturing conditions, and the heat shrinkage also changes by subjecting the film to a post-treatment such as heat treatment.

Therefore, in the organic polymer film used in the present invention, the difference between the heat shrinkage rate α _MD in the longitudinal direction after heat treatment at 150 ° C. for 15 minutes and the heat shrinkage rate α _TD in the width direction α _MD − If the absolute value of α _TD is 0.003 to 0.015, it may be the as-produced film or the film that has been subjected to post-treatment such as heat treatment. The alloy composition of the amorphous magnetic thin film formed on the substrate of the organic polymer film is Co-Fe-Si-B, Co-Si-B, Co-N.
Co-based alloys such as b-Zr, Co-Hf-Ta, Fe-Si-B, Fe-C, Fe-
Existing ones such as Fe-based alloys such as Zr can be used.

The heat shrinkage ratio in the present invention can be measured according to JIS C 2318 except that the heating time is 15 minutes. That is, width 20mm, length
Cut out 5 pieces of 150 mm test piece, set 2 marks at 100 mm distance in the center, leave them in a 150 ° C thermostat for 15 minutes, and measure the distance between marks. By performing this measurement in the longitudinal direction and the width direction, calculating the heat shrinkage ratio from the following formula (1), and taking the average value of them, the heat shrinkage ratios α _MD and α _TD in each direction can be obtained. .

[0012]

[Equation 1]

In the present invention, the sputtering apparatus used for producing the amorphous magnetic thin film having uniaxial magnetic anisotropy is, for example, RF bipolar sputtering, DC sputtering, magnetron sputtering, tripolar sputtering, ion beam sputtering. It is possible to use existing ones such as a facing target type sputter, and among them, the magnetron sputtering apparatus can improve the deposition rate of the thin film and suppress the temperature rise of the substrate to a relatively low level. This is advantageous when using a relatively low organic polymer film or the like. In addition, the magnetron sputtering method
In this method, a magnetic field is applied in a direction perpendicular to the electric field applied to the target, and the charged particles in the plasma are subjected to cyclotron motion to improve the sputtering efficiency, and the sputtered particles are deposited on a substrate installed in advance.

Here, as the magnetic field for the cyclotron motion of the charged particles, a leaking magnetic field of a permanent magnet or an electromagnet arranged directly under the target is used, or a yoke is used from a magnetic pole of the permanent magnet or the electromagnet to form a target surface. There is a method of directly inducing a magnetic flux to increase the leakage magnetic field. Further, in order to continuously produce a thin film, a roll-to-roll method in which an organic polymer film wound on a feed roll is deposited at a can portion can be used.

The production conditions for producing a soft magnetic thin film in a gas atmosphere vary depending on the size of the chamber and the exhaust capacity of the vacuum pump, but the ultimate pressure in the chamber during the production of the thin film is, for example, 5 preferably × at 10 ^-6 Torr or less, further more preferably not more than 1 × 10 ^-6 Torr. As the gas used in the present invention, it is preferable to use an inert gas, and examples of the inert gas include argon, helium and neon. As the flow rate of the inert gas, 20 to 200 CCM is suitable, 40 to 170 CCM is preferable, and 60 to 150 CCM is particularly preferable.

[0016]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. Example 1 Planar type magnetron sputtering apparatus (ULVAC
After pre-sputtering for 15 minutes, the absolute value of α _MD −α _TD is 0.005 and the thickness is 125 μm.
A 0.5 μm-thick Co-Fe-Si-B thin film was prepared by sputtering on a square polyethylene terephthalate film substrate having a side length of 150 mm. The manufacturing conditions at that time are shown below. Target composition: Co ₆₈ Fe _4.5 Si _12.5 B ₁₅ (Numbers indicate atomic%.) Ultimate pressure: 1 × 10 ^-7 Torr Sputtering pressure: 2 × 10 ^-3 Torr Argon gas flow rate: 70 CCM Sputtering power: 400 W

When the magnetization characteristics of the thin film produced under the above production conditions were measured with a sample vibrating magnetometer (VSM) (manufactured by Riken Denshi Co.), the width direction of the polyethylene terephthalate film was the easy axis of magnetization. . The magnetization curves along the easy axis and the hard axis are shown in Fig. 1 respectively.
And shown in FIG.

1 and 2, the vertical axis represents the magnetization amount M and the horizontal axis represents the applied magnetic field H. As is clear from these figures, the magnetization curve having a sharp rise in the easy magnetization axis direction. It was confirmed that the thin film has a good uniaxial magnetic anisotropy because it rises almost linearly with respect to the applied magnetic field in the hard axis direction until saturation is reached. Furthermore, when the structure of this thin film was examined with an X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.),
It was confirmed to be an amorphous single phase.

Example 2 Pre-sputtering was carried out for 20 minutes using a DC magnetron sputtering device (manufactured by ULVAC), and then α _MD −
The absolute value of α _TD is 0.007, the thickness is 100 μm, and the width is 300 mm.
Using the polyethylene terephthalate film of
A continuous Co-Fe-Si-B thin film with a thickness of 0.3 μm was prepared by the roll-to-roll method. This roll tow
The roll method is a method in which an organic polymer material such as a plastic film wound on a feed roll is deposited on a can portion while being wound on a take-up roll via a cylindrical can. Then, the above-mentioned polyethylene terephthalate film wound on the feed roll was continuously wound while being wound at a speed of 0.25 m / min via a cylindrical can. The manufacturing conditions at that time are shown below. Target composition: Co ₆₀ Fe ₁₅ Si ₁₀ B ₁₅ (Numbers indicate atomic%) Ultimate pressure: 8 × 10 ^-7 Torr Sputtering pressure: 1.5 × 10 ^-3 Torr Argon gas flow rate: 90CCM Sputtering power: 7kW

When the magnetization characteristics of the thin film produced under the above production conditions were measured in the same manner as in Example 1, the width direction of the polyethylene terephthalate film was the easy axis of magnetization. Magnetization curves in the easy axis and hard axis directions at that time are shown in FIGS. 3 and 4, respectively. 3 and 4
Indicates the amount of magnetization M on the vertical axis and the applied magnetic field H on the horizontal axis. As is clear from these figures, the magnetization curve has a sharp rise in the direction of the easy magnetization axis, and In the direction, it was confirmed that it had a good uniaxial magnetic anisotropy because it stood almost linearly with respect to the applied magnetic field until it reached saturation. Further, when the structure of this thin film was examined by an X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.), it was confirmed to be an amorphous single phase.

Comparative Example 1 Planar type magnetron sputtering apparatus (ULVAC
After pre-sputtering for 20 minutes, the same method as described in JP-A-5-82378 is used to perform sputtering on a 50 × 50 × 0.7 mm substrate with ET cut quartz. The Co-Fe-Si with a thickness of 0.5 μm.
-B thin film was prepared. Here, the same manufacturing conditions as in Example 1 were used except that the substrate temperature was set to 250 degrees. The magnetization characteristics of the produced thin film were measured in the same manner as in Example 1, and the magnetization curves in the easy axis and hard axis directions at that time are shown in FIGS. 5 and 6, respectively. 5 and 6, the vertical axis represents the magnetization amount M and the horizontal axis represents the applied magnetic field H. As is apparent from these figures, the magnetization curve in the hard axis direction is linear with respect to the applied magnetic field. The uniaxial magnetic anisotropy was incomplete. Furthermore, when the structure of this thin film was examined with an X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.),
It had a mixed structure of an amorphous phase and a crystalline phase.

Comparative Example 2 After pre-sputtering for 20 minutes using a DC magnetron sputtering device (manufactured by ULVAC), α _MD −
The absolute value of α _TD is 0.002, the thickness is 125 μm, and the width is 300 mm.
Using the polyethylene terephthalate film of
A continuous Co-Fe-Si-B thin film having a thickness of 0.3 µm was prepared by winding the roll-to-roll method at a speed of 0.25 m / min. Here, the same manufacturing conditions as in Example 1 were used. The magnetization characteristics of the produced thin film were measured in the same manner as in Example 1, and the magnetization curves in the easy axis and hard axis directions at that time are shown in FIGS. 7 and 8, respectively. 7 and 8
Shows the magnetization amount M on the vertical axis and the applied magnetic field H on the horizontal axis. As is clear from these figures, the easy axis and the hard axis are not clearly distinguished, and the uniaxial magnetic anisotropy is It was insufficient.

Example 3 Pre-sputtering was performed for 15 minutes using a DC magnetron sputtering apparatus (manufactured by ULVAC), and then α _MD −
The absolute value of α _TD is 0.009, the thickness is 100 μm, and the width is 500 mm.
Using the above polypropylene film as a substrate, a continuous Co-Fe-Si-B thin film having a thickness of 0.2 μm was produced by rolling at a speed of 0.4 m / min by a roll-to-roll method. The manufacturing conditions at that time are shown below. Target composition: Fe ₇₅ Si ₁₀ B ₁₅ (Numbers indicate atomic%.) Ultimate pressure: 7 × 10 ^-7 Torr Sputtering pressure: 1.5 × 10 ^-3 Torr Argon gas flow rate: 90CCM Sputtering power: 7kW

The magnetic properties of the produced thin film were measured in the same manner as in Example 1. The magnetization curve of the obtained thin film has a sharp rise in the easy-axis direction and rises almost linearly until it reaches saturation in the hard-axis direction, and therefore has good uniaxial magnetic anisotropy. Was confirmed. It was also confirmed that the structure of the thin film was an amorphous single phase.

Example 4 After pre-sputtering for 20 minutes using a DC magnetron sputtering device (manufactured by ULVAC), α _MD −
The absolute value of α _TD is 0.005, the thickness is 37 μm, the width is 300 mm, the nylon film is used as the substrate, and the thickness is 0.3 m / min while being wound by the roll-to-roll method at the speed of 0.3 m / min.
A Co-Nb-Zr thin film with a thickness of 50 μm was continuously formed. The manufacturing conditions at that time are shown below. Target composition: Co ₈₇ Nb ₈ Zr ₅ (Numbers indicate atomic%.) Ultimate pressure: 5 × 10 ^-7 Torr Sputtering pressure: 1.5 × 10 ^-3 Torr Argon gas flow rate: 100 CCM Sputtering power: 5 kW

The magnetic properties of the produced thin film were measured in the same manner as in Example 1. The magnetization curve of the obtained thin film has a sharp rise in the easy-axis direction and rises almost linearly until it reaches saturation in the hard-axis direction, indicating that it has good uniaxial magnetic anisotropy. It could be confirmed. Moreover, the magnetic properties were uniform in the longitudinal direction, and it was possible to produce a large amount of thin films having good uniaxial magnetic anisotropy. It was also confirmed that the structure of the thin film was an amorphous single phase.

[0027]

According to the present invention, good uniaxial magnetic anisotropy can be imparted to an amorphous magnetic thin film over a wide area, and the produced amorphous magnetic thin film can be used as an antitheft marker, It can be used for various pulse generating elements such as a magnetic sensor and a rotation sensor, and since an organic polymer film is used for a substrate, it can be mass-produced continuously.

[Brief description of drawings]

FIG. 1 is a magnetization curve showing the magnetic characteristics of the amorphous magnetic thin film obtained in Example 1, measured on the easy axis of magnetization.

FIG. 2 is a magnetization curve showing the magnetic characteristics of the amorphous magnetic thin film obtained in Example 1, measured on the hard axis.

FIG. 3 is a magnetization curve showing the magnetic characteristics of the amorphous magnetic thin film obtained in Example 2 measured with the easy axis of magnetization.

FIG. 4 is a magnetization curve showing the magnetic characteristics of the amorphous magnetic thin film obtained in Example 2, measured on the hard axis of magnetization.

5 is a magnetization curve showing the magnetic characteristics of the magnetic thin film obtained in Comparative Example 1 measured with the easy axis of magnetization. FIG.

FIG. 6 is a magnetization curve showing the magnetic characteristics of the magnetic thin film obtained in Comparative Example 1, measured on the hard axis.

7 is a magnetization curve showing the magnetic characteristics of the amorphous magnetic thin film obtained in Comparative Example 2 measured with the easy axis of magnetization.

FIG. 8 is a magnetization curve showing the magnetic characteristics of the amorphous magnetic thin film obtained in Comparative Example 2, measured on the hard axis.

Claims (1)

[Claims] 1. When forming an amorphous magnetic thin film on a substrate by sputtering a target in a gas atmosphere, the heat shrinkage ratio α _MD in the longitudinal direction after heat treatment as a substrate for 15 minutes at 150 ° C. The difference between the heat shrinkage ratio α _TD in the width direction and the absolute value of α _MD −α _TD is 0.003 to 0.015. An amorphous polymer thin film having uniaxial magnetic anisotropy characterized by using an organic polymer film is used. Production method.