JPH05234799A - Manufacture of single-crystal magnetic film - Google Patents

Abstract

PURPOSE:To make it possible to manufacture a single-crystal magnetic film with a high productivity by setting the energy of a charged beam to a specific range and maintaining the temperature of a substrate within a specific range when an Fe-based or Fe-Co-based single-crystal magnetic film is manufactured on a substrate by sputtering a target with a charged beam. CONSTITUTION:A substrate holder 2 is disposed within a vacuum chamber 1, and a substrate 3 is mounted on this substrate holder 2. A target holder 4 is rotatably positioned within the vacuum chamber 1, and targets 5 are mounted on this target holder 4. A charged beam generating source 6 is placed within the chamber 1 in such a manner as to be opposite to the target 5. In order to produce an Fe-based or Fe-Co-based single-crystal magnetic film over the substrate, the temperature of the substrate is set within a range between a room temperature and 500 deg.C, and the energy of the charged beam is set within a range between 300 and 500 eV, whereby a single crystal possessing a superior magnetic property can be obtained with a high productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an Fe-based or Fe-Co-based single crystal magnetic film used as a magnetic film of various planar magnetic elements.

[0002]

2. Description of the Related Art In recent years, with the progress of integrated circuit technology represented by LSI and the like, miniaturization of various electronic devices has been actively promoted. Along with this, the tendency that the volume ratio of the power supply unit in the entire device increases has become remarkable. This is because miniaturization and integration of magnetic components such as inductors and transformers essential for the power supply unit are delayed as compared with other components. In order to solve this problem, a planar magnetic element in which a planar coil and a magnetic body are combined has been proposed, and its performance improvement is being studied. These plane type magnetic elements have come to be manufactured using a thin film process such as a thin film manufacturing technique and a fine processing technique. The magnetic characteristics of the magnetic thin film are important when manufacturing an ultra-small planar magnetic element.

First, when the application as a high frequency power element is considered, the saturation of the magnetic film due to the magnetic field generated by the DC superimposed current becomes a problem. Therefore, the magnetic film is required to have high saturation magnetization. Further, when an alternating current is applied to the spiral coil 11 as shown in FIG. 2A, a magnetic field is generated in the direction indicated by the arrow in the figure. In this case, if the magnetization vector of the magnetic film 12 sandwiching the coil is in the direction as shown in FIG. 2B and has a magnetic domain structure surrounded by 90 degree domain walls, the magnetic film 12 has The only magnetization process is rotational magnetization. As a result, a low loss inductor having excellent high frequency characteristics can be obtained.

When conventional soft magnetic thin films such as permalloy, sendust, and Co type amorphous alloy are used for various ultra-small plane type magnetic elements, saturation magnetization is often insufficient. Therefore, in order to realize high performance and high integration of the planar magnetic element, it has been considered to use a magnetic thin film having a saturation magnetization of 2 Tesla class. Fe-based and Fe-Co-based magnetic materials have the largest spontaneous magnetization value among 3d transition metal-based magnetic materials, and their saturation magnetization can exceed 2 tesla. Therefore, they are regarded as promising new magnetic thin film materials. There is. However, these material systems have a magnetic anisotropy K
Also, the magnetostriction λ is large, and it is difficult to form a soft magnetic thin film. Further, as the operating frequency becomes higher, lower loss is required. Therefore, the magnetic domains are controlled by single crystallization of the magnetic film as shown in FIG. 2B, and the single crystal magnetic film and the insulating film are controlled. It is important to form a multilayer by combining with a non-magnetic metal film or a semiconductor film.

To date, Fe-based single crystal films have been produced using a vacuum deposition method such as molecular beam epitaxy (MBE). By using this method, an Fe single crystal film can be produced, but there is a problem of low throughput. Therefore, it is preferable that the Fe-based and Fe-Co-based single crystal films can be produced by a method such as sputtering with higher productivity.

[0006]

As described above, in the past, when manufacturing an ultra-small planar magnetic element, the F
Although an example of producing an e single crystal film is known, there is a problem of low productivity. An object of the present invention is to provide a method capable of producing a Fe-based or Fe-Co-based single crystal film applied to a microminiature planar magnetic element with high productivity.

[0007]

The method for producing a single crystal magnetic film of the present invention is to produce a Fe-based or Fe-Co-based single crystal magnetic film on a substrate by sputtering a target with a charged beam. The energy of the charged beam is set in the range of 300 to 5000 eV, and the substrate temperature is kept in the range of room temperature to 500 ° C.

FIG. 1 shows a single crystal thin film manufacturing apparatus used in the present invention. A substrate holder 2 is provided in the vacuum chamber 1, and a substrate 3 is placed on the substrate holder 2. The substrate holder 2 has a structure that can be heated by a heater.
A target holder 4 is rotatably installed in the vacuum chamber 1, and a target 5 is placed on the target holder 4. A charged beam generating source 6 is provided in the vacuum chamber 1 so as to face the target 5. A mass spectrometer 7 is attached to the vacuum chamber 1.

The material of the vacuum chamber is not particularly limited. It is desirable that the vacuum chamber can be evacuated to 1 × 10 ⁻⁶ Torr or less. The specific method of evacuation is not particularly limited. However, it is preferable to suppress the partial pressure of H ₂ O and O ₂ contained in the atmosphere in the vacuum chamber to 10 ^-9 Torr or less. For this reason, it is preferable that the vacuum chamber is made of an Al alloy, a stainless alloy having a mirror-finished interior, or the like. Further, it is preferable that the inside of the piping for sputtering gas, purge gas, etc. is also mirror-finished. H ₂ O in a vacuum chamber
The method of managing the absolute amount of is not particularly limited, but it is effective to monitor the dew point on the exhaust side.

As the substrate, MgO, Si, CaF ₂ ,
A single crystal substrate made of GaAs, various metals, etc. may be mentioned, but it is not particularly limited. The substrate temperature is kept in the range of room temperature to 500 ° C. However, it is difficult to obtain a single crystal with a film thickness of 500 nm or more at room temperature, although the numerical values vary depending on the substrate. For example, in the case of a single crystal MgO substrate, the optimum temperature is 150 to 350 ° C. At this time, it is preferable to suppress the in-plane temperature distribution of the substrate holder to 5% or less in order to make the crystallinity uniform in the in-plane of the substrate. As a method thereof, there is a method of dividing the heater into some blocks and attaching a temperature sensor to each block to control the temperature, but the method is not limited to this. Also,
It is important that the material of the interlayer film when the single crystal magnetic film is formed into multiple layers is a material that does not easily react with the magnetic thin film, but is not particularly limited. Specifically, Si, Ge, SiO ₂ ,
GaAs, GaAlAs, MgO, Al ₂ O ₃ , Si _x
N _y , Al _x N _y , SiC, diamond, CaF ₂ ,
Ta ₂ O ₅ or the like can be mentioned. As the target, Fe having almost the same composition as the single crystal film to be formed on the substrate is used.
Based or Fe-Co based targets are used.

Ar is typically used as the sputtering gas, but rare gases such as Ne and Kr may be used. The purity of the gas is preferably 99.9999% or more and an ultrahigh purity.

Examples of the charged beam generating source include various ion sources such as a Kauffman type, a saddle field type, a hollow cathode type, an ECR plasma type (including a type using a strong magnetic field), but are not particularly limited. The energy of the charged beam is different for each ion source,
It is set in the range of 0 to 5000 eV. In particular, in the Kaufman type or ECR plasma type ion source, the energy of the charged beam is 300 to 1000 as the normal operation region.
It is often set in the range of eV. Outside this range, it is difficult to produce a single crystal film having good magnetic properties. Further, a particularly preferable range for obtaining a magnetic film having a saturation magnetization of 2 tesla or more and a coercive force of 1 Oe or more is 400 to 800 eV.

[0013]

EXAMPLES Examples of the present invention will be described below. In the examples below, the acceleration voltage of the ion source is described.
However, the value of the acceleration voltage of the ion source and the value obtained by converting this into the energy of the charged beam are numerically almost equivalent. Example 1

Mg having a (100) surface as a substrate
An O single crystal substrate was used. Purity 99.9 as target
99% Fe was used. A Kauffman type ion source was used as a charged beam source.

The inside of the vacuum chamber was evacuated to 1 × 10 ^-7 Torr or less. Ultra high purity Ar gas was introduced into the vacuum chamber to raise the pressure to 1 × 10 ⁻⁴ Torr. H ₂ O in the vacuum chamber
Purging with Ar gas was continued while monitoring with a mass spectrometer until the partial pressure of 1 was less than 1 × 10 ⁻⁹ Torr.

A Kauffman type ion source was operated, an Ar ion beam was generated under the conditions of an acceleration voltage of 500 V and a beam current of 30 mA, and an Fe target was sputtered. During this period, the MgO substrate was rotated at 20 rpm and the substrate temperature was set to 3
It was set to 00 ° C.

Under these conditions, an Fe film having an average film thickness of 1 μm was produced. The crystallinity of this film was examined by RHEED, TEM and X-ray diffraction, and the magnetic characteristics were examined by VSM.
As a result, it was confirmed that an Fe thin film having a bcc phase, which is close to a single crystal, was obtained although it contained some dislocations. The saturation magnetization was 2.1 T and the coercive force was 100 mOe. Example 2

Mg having a (100) surface as a substrate
An O single crystal substrate was used. Purity 99.9 as target
A 9% Fe _0.75 Co _0.25 alloy was used. A Kauffman type ion source was used as a charged beam source.

The inside of the vacuum chamber was evacuated to 1 × 10 ^-7 Torr or less. Ultra high purity Ar gas was introduced into the vacuum chamber to raise the pressure to 1 × 10 ⁻⁴ Torr. H ₂ O in the vacuum chamber
Purging with Ar gas was continued while monitoring with a mass spectrometer until the partial pressure of 1 was less than 1 × 10 ⁻⁹ Torr.

A Kauffman type ion source was operated, an Ar ion beam was generated under the conditions of an acceleration voltage of 600 V and a beam current of 30 mA, and an Fe _0.75 Co _0.25 target was sputtered. During this period, the MgO substrate is rotated at 50 rpm,
The substrate temperature was set to 400 ° C.

Under these conditions, Fe _0.75 Co having an average film thickness of 1 μm
_{A 0.25} film was prepared. About this film, RHEED, TE
Crystallinity was examined by M and X-ray diffraction, and magnetic characteristics were examined by VSM. As a result, although some dislocations are included,
It was confirmed that a bcc-phase Fe _0.75 Co _0.25 alloy thin film having a nearly single crystal structure was obtained. Saturation magnetization is 2.4
T, coercive force was 100 mOe. Example 3

Mg having a (100) surface as a substrate
An O single crystal substrate was used. Purity 99.9 as target
A 99% Fe _0.75 Co _0.25 alloy was used. An ion source using ECR plasma was used as a charged beam generation source.

The inside of the vacuum chamber was evacuated to 1 × 10 ^-7 Torr or less. Ultra high purity Ar gas was introduced into the vacuum chamber to raise the pressure to 1 × 10 ⁻⁴ Torr. H ₂ O in the vacuum chamber
Purging with Ar gas was continued while monitoring with a mass spectrometer until the partial pressure of 1 was less than 1 × 10 ⁻⁹ Torr.

An ECR plasma ion source was operated, an Ar ion beam was generated under the conditions of an acceleration voltage of 400 V and a beam current of 30 mA, and a Fe _0.75 Co _0.25 target was sputtered. During this period, the MgO substrate was rotated at 40 rpm and the substrate temperature was set to 200 ° C.

Under these conditions, Fe _0.75 Co having an average film thickness of 1 μm
_{A 0.25} film was prepared. About this film, RHEED, TE
Crystallinity was examined by M and X-ray diffraction, and magnetic characteristics were examined by VSM. As a result, although some dislocations are included,
It was confirmed that a bcc-phase Fe _0.75 Co _0.25 alloy thin film having a nearly single crystal structure was obtained. Saturation magnetization is 2.4
T, coercive force was 10 mOe. Example 4

Mg having a (100) surface as a substrate
An O single crystal substrate was used. Purity of 99.
9999% Cu and 99.999% pure Fe _0.75
A Co _0.25 alloy was used. ECR as a charged beam source
A plasma ion source was used.

The inside of the vacuum chamber was evacuated to 1 × 10 ^-7 Torr or less. Ultra high purity Ar gas was introduced into the vacuum chamber to raise the pressure to 1 × 10 ⁻⁵ Torr. H ₂ O in the vacuum chamber
Purging with Ar gas was continued while monitoring with a mass spectrometer until the partial pressure of 1 was less than 1 × 10 ⁻⁹ Torr.

The ECR plasma ion source was activated to generate an Ar ion beam under the conditions of an acceleration voltage of 500 V and a beam current of 30 mA. First, a Cu target was sputtered. At this time, the MgO substrate was rotated at 20 rpm and the substrate temperature was set to 300 ° C. As for the orientation of the grown Cu film, Cu (100) is parallel to MgO (100),
Cu <100> was parallel to MgO <100>. Next, a Fe _0.75 Co _0.25 target was sputtered. At this time, the MgO substrate was rotated at 20 rpm and the substrate temperature was set to 150 ° C.

Under this condition, the average film thickness of 1 on the Cu single crystal film surface.
A Fe _0.75 Co _0.25 film having a thickness of μm was prepared. The crystallinity of this film was examined by RHEED, TEM and X-ray diffraction, and the magnetic characteristics were examined by VSM. As a result, although some dislocations are included, the Fcc phase F that is almost a single crystal is obtained.
It was confirmed that an e _0.75 Co _0.25 alloy thin film was obtained. The saturation magnetization was 3.5 T and the coercive force was 10 mOe. Example 5

Mg having a (100) surface as a substrate
An O single crystal substrate was used. Purity 99.9 as target
99% Fe was used. A Kauffman type ion source was used as a charged beam source.

The inside of the vacuum chamber was evacuated to 1 × 10 ^-7 Torr or less. Ultra high purity Ar gas was introduced into the vacuum chamber to raise the pressure to 1 × 10 ⁻⁴ Torr. H ₂ O in the vacuum chamber
Purging with Ar gas was continued while monitoring with a mass spectrometer until the partial pressure of 1 was less than 1 × 10 ⁻⁹ Torr.

A Kauffman type ion source was operated, an Ar ion beam was generated under the conditions of an acceleration voltage of 700 V and a beam current of 30 mA, and an Fe target was sputtered. At this time, the MgO substrate was rotated at 10 rpm and the substrate temperature was set to 3
It was set to 00 ° C. Under these conditions, F with an average film thickness of 500 nm
An e film was prepared. About this film, RHEED, TE
Crystallinity was examined by M and X-ray diffraction. As a result, it was confirmed that the film was a single crystal film. Next, by a plasma CVD method using SiH ₄ and O ₂ as raw materials, ₂ is formed on the Fe single crystal film.
A 00 nm single crystal SiO ₂ film was formed. Do this operation 5
Repeated times to form a laminated structure.

Crystallinity was examined by RHEED, TEM and X-ray diffraction, and magnetic properties were examined by VSM. as a result,
Although it contains some dislocations, it has a bcc close to that of a single crystal.
It was confirmed that a phase Fe thin film was obtained. The saturation magnetization was 2.1 T and the coercive force was 100 mOe. Furthermore, when this thin film was applied as a magnetic film of a planar inductor, the upper limit of the common frequency band was 10 MHz. Example 6

As a substrate, Ga whose surface is a (100) plane
An As single crystal substrate was used. Purity as target 99.
999% Fe and single crystal GaAlAs were used. An ECR plasma type ion source was used as a charged beam generation source.

The inside of the vacuum chamber was evacuated to 1 × 10 ^-7 Torr or less. Ultra high purity Ar gas was introduced into the vacuum chamber to raise the pressure to 1 × 10 ⁻⁵ Torr. H ₂ O in the vacuum chamber
Purging with Ar gas was continued while monitoring with a mass spectrometer until the partial pressure of 1 was less than 1 × 10 ⁻⁹ Torr.

An ECR plasma type ion source was operated, an Ar ion beam was generated under the conditions of an acceleration voltage of 500 V and a beam current of 20 mA, and an Fe target was sputtered.
At this time, the GaAs substrate was rotated at 20 rpm and the substrate temperature was set to 250 ° C. Under this condition, the average film thickness is 50 nm
Fe film was prepared. The crystallinity of this film was examined by RHEED. As a result, it was confirmed that the film was a single crystal film. Next, acceleration voltage 500V, beam current 20m
Under the condition of A, a 20 nm single crystal GaA is formed on the Fe single crystal film.
An lAs film was formed. At this time, the substrate was rotated at 30 rpm and the substrate temperature was set to 150 ° C. Do this operation 20
Repeated times to form a laminated structure.

The surface properties, cross-sectional structure and crystallinity of the laminated film were examined by RHEED, TEM and X-ray diffraction, and the magnetic properties were examined by VSM. As a result, the bcc phase Fe thin film and GaAlA, which are close to a single crystal, although they contain some dislocations,
It was confirmed that a laminated structure of the s film was obtained. The saturation magnetization was 2.1 T and the coercive force was 100 mOe. Furthermore, when this thin film was applied as a magnetic film of a planar inductor, the upper limit of the common frequency band was 100 MHz. Example 7

As a substrate, Ga whose surface is a (100) plane
An As single crystal substrate was used. Purity as target 99.
A 999% Fe _0.75 Co _0.25 alloy was used. A saddle field type ion source was used as the charged beam source.

The inside of the vacuum chamber was evacuated to 1 × 10 ^-7 Torr or less. Ultra high purity Ar gas was introduced into the vacuum chamber to raise the pressure to 1 × 10 ⁻⁴ Torr. H ₂ O in the vacuum chamber
Purging with Ar gas was continued while monitoring with a mass spectrometer until the partial pressure of 1 was less than 1 × 10 ⁻⁹ Torr.

Actuating the saddle field type ion source,
An Ar ion beam was generated under the conditions of an accelerating voltage of 5 kV and a beam current of 3 mA to sputter a Fe _0.75 Co _0.25 alloy target. At this time, the GaAs substrate was rotated at 20 rpm and the substrate temperature was set to 250 ° C. Under this condition, an Fe _0.75 Co _0.25 alloy film having an average film thickness of 50 nm was produced.
The crystallinity of this film was examined by RHEED. As a result, it was confirmed that the film was a single crystal film. Next, Si
Fe _{0.75 was} obtained by a thermal CVD method using H ₄ and CH ₄ as raw materials.
20 nm single crystal β-SiC on a Co _0.25 alloy single crystal film
A film was formed. This operation was repeated 20 times to form a laminated structure.

The surface properties, cross-sectional structure and crystallinity of the laminated film were examined by RHEED, TEM and X-ray diffraction, and the magnetic properties were examined by VSM. As a result, the Fe _0.75 Co _0.25 alloy film and β-S, which are close to a single crystal, contain some dislocations.
It was confirmed that a laminated structure with the iC film was obtained.
The saturation magnetization was 2.1 T and the coercive force was 100 mOe.
Furthermore, when this thin film was applied as a magnetic film of a planar inductor, the upper limit of the common frequency band was 100 MHz. Example 8

As the substrate, a high-pressure synthetic diamond single crystal substrate having a (100) surface was used. As a target, an Fe _0.75 Co _0.25 alloy having a purity of 99.999% and Cu having a purity of 99.9999% were used. An ion source using ECR plasma was used as a charged beam generation source.

The inside of the vacuum chamber was evacuated to 1 × 10 ^-7 Torr or less. Ultra high purity Ar gas was introduced into the vacuum chamber to raise the pressure to 1 × 10 ⁻⁴ Torr. H ₂ O in the vacuum chamber
Purging with Ar gas was continued while monitoring with a mass spectrometer until the partial pressure of 1 was less than 1 × 10 ⁻⁹ Torr.

The ECR plasma ion source was operated, an Ar ion beam was generated under the conditions of an acceleration voltage of 500 V and a beam current of 20 mA, and a Fe _0.75 Co _0.25 target was sputtered. At this time, the diamond single crystal substrate is set to 10 rp.
The substrate temperature was set to 150 ° C. by rotating at m. The crystallinity of this film was examined by RHEED. As a result, it was confirmed to be a single crystal having a face-centered cubic structure. Next, a 20 nm Cu film was formed on the Fe _0.75 Co _0.25 alloy film under the conditions of an acceleration voltage of 500 V and a beam current of 20 mA. At this time, the substrate was rotated at 20 rpm and the substrate temperature was set to 150 ° C. About this membrane, RHEED
The crystallinity was investigated by. As a result, it was confirmed to be a single crystal having a face-centered cubic structure. This operation was repeated 20 times to form a laminated structure.

The surface properties, sectional structure and crystallinity of the laminated film were examined by RHEED, TEM and X-ray diffraction, and the magnetic properties were examined by VSM. As a result, it was confirmed that a laminated structure of an Fe _0.75 Co _0.25 alloy film of the fcc phase and a Cu film, which is close to a single crystal, although including some dislocations, was obtained. The saturation magnetization was 3.5 T and the coercive force was 100 mOe. Furthermore, when this thin film was applied as a magnetic film for a planar inductor, the upper limit of the common frequency band was 100 MHz.
And the upper limit of usable power was 50W.

[0046]

As described in detail above, by using the method of the present invention, a Fe-based or Fe-Co-based single crystal film applied to an ultra-small planar magnetic element can be manufactured with high productivity.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a sputtering apparatus used in an example of the present invention.

FIG. 2A is a diagram showing a direction of a magnetic field generated when an alternating current flows in a spiral coil, and FIG. 2B is a diagram showing a direction of a magnetization vector introduced into a magnetic film.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum tank, 2 ... Substrate holder, 3 ... Substrate, 4 ... Target holder, 5 ... Target, 6 ... Charged beam generation source, 7
... mass spectrometer, 11 ... spiral coil, 12 ... magnetic film.

Claims (1)

[Claims] 1. When a target is sputtered with a charged beam to produce an Fe-based or Fe-Co-based single crystal magnetic film on a substrate, the energy of the charged beam is set in the range of 300 to 5000 eV, and the substrate temperature is set. A method for producing a single crystal magnetic film, which is characterized in that the temperature is maintained in the range of room temperature to 500 ° C.