JPH08218164A - Sputtering target for forming soft magnetic thin film - Google Patents

Abstract

PURPOSE: To develop a target for forming the soft magnetic thin film for a plane magnetic element of high resistivity and high saturation magnetic flux density by sputtering by arranging a B4 C chip on an Fe-Co alloy of specified composition. CONSTITUTION: A plane magnetic element as a combination of the plane coil and laminated magnetic material is used for the magnetic parts of a power source to miniaturize the power source as the various electrical instruments are miniaturized. A soft magnetic thin film having a low loss and a high saturation magnetization in a high-frequency region is formed by sputtering and used as the magnetic material to be used in the plane magnetic element. A target having the composition shown by (Fe1-x Cox )1-y (B1-z Xz )y (wherein, X represents one or more than two elements selected from the IVb group in periodic table, N and P; and x, y and z satisfy inequalities, 0<=x<=0.5, 0.06<y<0.5 and 0<z<1, respectively) and having a uniform and small permeability over the entire face is used as the target to be used for the plane magnetic element. The soft magnetic thin film has such a microstructure that a first amorphous layer 1 contg. Fe and Co is surrounded with a second amorphous layer 2 contg. group IVa elements such as B and C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target for forming a soft magnetic thin film.

[0002]

2. Description of the Related Art In recent years, miniaturization of various electronic devices has been actively promoted. However, miniaturization of the power supply section of electronic equipment is delayed compared to that. For this reason, the volume ratio of the power supply unit to the entire electronic device is increasing. The miniaturization of electronic devices is largely due to the LSI of various circuits. However, with regard to magnetic components such as inductors and transformers that are indispensable for power supply units, such miniaturization and integration are delayed, This is the main cause of the increase in the volume ratio of the power supply unit to the entire equipment.

In order to solve such a problem, as an inductor or a transformer as a magnetic component of a power source,
Planar type magnetic elements have been proposed in which a planar coil and a laminated magnetic material are combined, and studies are being made to improve their performance and further reduce their size.

The magnetic material used in this planar magnetic element is required to have a low loss and a high saturation magnetic flux density in a high frequency region of 1 MHz or higher, for example. As the operating frequency of magnetic elements shifts from 10MHz to 100MHz in the future, it is considered that compatibility between low loss and high saturation magnetization at high frequencies will become an even more important issue.

That is, in high-frequency excitation, eddy current loss becomes remarkable, and therefore, it is necessary to stack magnetic bodies and increase the efficiency of the magnetic bodies themselves in order to reduce the loss. Further, high saturation magnetization is required to increase the inductance density and energy density.

Also in a magnetic head and the like, a magnetic material having a low loss and a high saturation magnetization in a high frequency region is accompanied by an increase in recording density, a high coercive force of a medium, a high energy product, and a high operating frequency. Is required.

These requirements also apply to other magnetic elements. Conventionally, amorphous magnetic alloy ribbons or soft magnetic thin films have been studied as magnetic materials used in magnetic elements that meet these requirements, and among them, soft magnetic thin films can be made thinner and manufactured as It is said that the film is more effective than the amorphous magnetic alloy ribbon by adopting the sputtering method or the like because the amorphous film can be obtained in a wider range.

By the way, in the high frequency region, the magnetic permeability is mainly covered by the rotating magnetization process. Therefore, excitation in the hard axis direction becomes important, and high-frequency permeability and high-frequency loss in the hard axis direction become important physical property values.

The high-frequency permeability is an amount that is complicatedly related to various physical properties of a sample, and the anisotropic magnetic field is the one having the highest correlation. Generally, the high frequency magnetic permeability changes in proportion to the reciprocal of the anisotropic magnetic field.

Therefore, in order to realize high saturation magnetization, high magnetic permeability and low loss of the soft magnetic thin film used in the high frequency region as described above, the magnetic thin film should have uniaxial anisotropy and a small amount. It is necessary to have uniaxial anisotropy energy in the soft magnetic thin film which is not too much.

As a material of the magnetic thin film satisfying such requirements, for example, a general transition metal alloy film has a too low resistivity, and in order to use it as a magnetic body of a magnetic element, the number of laminated layers must be increased. A complex structure such as insufficient characteristics cannot be obtained, which is not sufficient from the viewpoint of manufacturing process and manufacturing cost.

In addition, oxide materials such as soft ferrite having high and low efficiencies have a small saturation magnetization and are small in size.
Not suitable for high output. To overcome the shortcomings of the materials used in these conventional soft magnetic thin films, recently,
Hetero-amorphous films are being researched and developed.
63-119209). However, in such a system, although a soft magnetic thin film with high saturation magnetization and high and low efficiency has been obtained, only a magnetically isotropic soft magnetic thin film has been obtained. This is not suitable for giving and controlling the magnetic permeability optimized for the characteristics of the magnetic element. In particular, a microminiature thin film inductance element or the like requires in-plane uniaxial magnetic anisotropy of a specific size.

Therefore, a soft magnetic thin film which can secure a desired magnetic permeability by excitation of a hard axis of magnetization by satisfying and controlling in-plane uniaxial magnetic anisotropy, and which has a high magnetic permeability and a high low efficiency is desired. .

[0014]

As described above, a soft magnetic thin film satisfying a high saturation magnetization and a low loss in a high frequency region is demanded for a flat type magnetic element or the like for coping with miniaturization of a magnetic element. Therefore, satisfying high saturation magnetization while maintaining high resistivity is an essential condition for the soft magnetic thin film. Further, in order to impart a desired high magnetic permeability to a flat magnetic element or the like, it is important to obtain a high frequency magnetic permeability by hard axis excitation. For this purpose, it is necessary to impart in-plane uniaxial magnetic anisotropy to the soft magnetic thin film and enhance its controllability.

Further, a method for forming a soft magnetic thin film which solves such a problem is currently being researched and developed together with the composition of the soft magnetic thin film. The present invention has been made to solve the above problems, and has a high saturation magnetization and a high saturation magnetization in a soft magnetic thin film used for a planar magnetic element or the like capable of achieving miniaturization and high performance. An object of the present invention is to provide a sputtering target for forming a soft magnetic thin film for forming a soft magnetic thin film which has both high resistivity and facilitates acquisition of high frequency magnetic permeability due to hard axis excitation.

[0016]

Means and Actions for Solving the Problems The sputtering target for forming a soft magnetic thin film of the present invention has the following general formula: (Fe _1-x Co _x ) _1-y (B _1-z X _z ) _y (In the formula, x represents one or more elements selected from IVb group elements, N and P, and x, y and z are each 0 ≦ x.
≦ 0.5, 0.06 <y <0.5, 0 <z <1).

Then, the soft magnetic thin film obtained by performing sputtering using the sputtering target for forming a soft magnetic thin film of the present invention is an amorphous soft magnetic thin film, which is the first amorphous material responsible for magnetism. It is possible to obtain an in-plane uniaxial magnetic anisotropy, including a phase and a second amorphous phase having a high resistance arranged around the first amorphous phase.

Specifically, the obtained amorphous soft magnetic thin film comprises a first amorphous phase having a magnetism containing one or two kinds selected from iron (Fe) and cobalt (Co), It is arranged around the first amorphous phase and is composed of boron (B) and a second amorphous phase containing one or more elements selected from IVb group elements, N and P. This amorphous soft magnetic thin film can have uniaxial magnetic anisotropy in the plane, because it has a microstructure as at least a part of the thin film forming region.

Here, as a concrete constitutional example of the first amorphous phase, for example, Fe group magnetism, Fe--Co group or C
An example is an o-based magnetic amorphous phase. Fe, which is a ferromagnetic material
Since the first amorphous phase mainly composed of Fe or Co is surrounded by the second amorphous phase mainly composed of B- (IVb group element, N, P) exhibiting high resistance, Since the soft magnetic thin film as a whole exhibits high resistance, and the islands of the first amorphous phase are magnetically coupled to each other, high saturation magnetization can be obtained.

It is sufficient that such a multi-phase amorphous phase is present as at least a part of the thin film forming region, but in a more preferable form, the entire film is substantially the same as the multi-phase amorphous phase. It is to be.

As described above, the film structure in which the second amorphous phase exhibiting a high resistance is arranged in a mesh pattern around the first amorphous phase having magnetism is It can be obtained by controlling the thin film composition.

Regarding the film composition, when the first amorphous phase is an Fe group, B as a sputtering target is used.
The composition ratio of is preferably 5 to 40 atomic%. When the composition ratio of B is too small, high resistance cannot be obtained in the obtained soft magnetic thin film, and when the composition ratio is too large, high saturation magnetization cannot be obtained in the obtained soft magnetic thin film. In this composition ratio range, high resistance can be obtained without significantly losing the saturation magnetic flux density of amorphous Fe. Further, in this composition ratio range, uniaxial magnetic anisotropy is easily obtained. Particularly preferably, the composition ratio of B is in the range of 5 to 20 atomic%.

Regarding the group IVb elements, N and P, the composition ratio as a sputtering target is 3 to 15 atom%.
It is preferable to set the range to C, and among the IVb group elements, N and P, C and the like are particularly preferably used.

Further, the first amorphous phase containing a Fe-Co type transition metal as a main component is effective for obtaining a high saturation magnetization. Such an Fe-Co group is a material that exhibits the maximum saturation magnetization in the crystalline transition metal alloy. In the amorphous state, the band structure changes depending on the element species of the metalloid element, the amount added, and the like, so it cannot be said to be the maximum, but it is one of the materials exhibiting high saturation magnetization.

Further, Fe-rich Fe-Co-based ones have a larger magnetostriction constant than Fe or the like. This is effective in inducing magnetic anisotropy related to magnetoelastic energy via magnetostriction.

Specifically, film formation in a magnetic field, high temperature film formation in a magnetic field, film formation of a substrate having uniaxial anisotropy in elastic modulus and thermal expansion coefficient, heat treatment in a magnetic field, to a substrate in which strain is introduced Film formation,
After film formation, magnetic anisotropy is induced by a single treatment or a composite treatment such as induction of strain on the substrate or the soft magnetic thin film.

From such a point, in the composition of the sputtering target, the value of x (composition ratio of Fe--Co)
Is a range satisfying 0 ≦ x ≦ 0.5. Furthermore, considering the magnetic moment and magnetostriction constant per transition metal element,
It is desirable that the range is 0.1 ≦ x ≦ 0.4.

It is also preferable to use two kinds of transition metal elements, Fe and Co, instead of the transition metal element alone, because the induction of magnetic anisotropy according to the orientational ordered arrangement can be expected. Specifically, it can be induced by heat treatment in a magnetic field or film formation in a magnetic field.

In addition to these, the Fe--Co group is a system showing the highest Curie temperature among transition metal type amorphous materials,
Further, the Curie temperature can be easily controlled by the composition ratio of Fe and Co. For example, a microminiature thin film inductance element generally has a high unit volume density of electric power to be handled, and it is expected that the temperature will rise to some extent even when a soft magnetic thin film having a sufficiently low loss is used. In general, since various magnetic characteristics represented by magnetization have temperature dissimilarity, the element characteristics may change depending on the operating state. In order to reduce this, it is effective to be able to adjust the Curie point.

In the soft magnetic thin film obtained by the sputtering target for forming a soft magnetic thin film of the present invention, Fe
Group IVb elements represented by B and C, N and P are used as metalloid elements for amorphizing the transition metal rich phase mainly containing —Co.

Further, these elements form a second amorphous phase containing both B and IVb group elements, N and P. This second amorphous phase has a strong covalent bond and exhibits a high resistivity.

In order to obtain such a second amorphous phase, the value of z is 0 <z in the composition of the sputtering target containing both B and IVb group elements, N and P.
It is essential that the range is <1.

In a system having a magnetic phase mainly composed of Fe-Co, when the metalloid element is insufficient, there is a possibility that a mixed phase film of a body-centered transition metal crystalline phase and an amorphous phase is formed. In some cases, sufficient soft magnetic characteristics may not be obtained. In order to avoid this, it is effective to set the composition ratio y of the typical element (non-transition metal element) to a value exceeding 0.06. Further, from the viewpoint of maintaining high saturation magnetization, y is set to less than 0.5.

By the way, the composition ratio y of the above-mentioned typical element (non-transition metal element) has a great influence on the provision and control of the in-plane uniaxial magnetic anisotropy, and it is sufficient to optimize the value of this composition ratio y. In-plane uniaxial magnetic anisotropy can be obtained.

FIG. 8 shows a relational example (experimental example) of the composition ratio y of the soft magnetic thin film obtained by the sputtering target for forming the soft magnetic thin film and the magnetic anisotropy energy ε _a per atom of the transition metal. . Details will be shown in the embodiment, but this FIG.
As is clearer, Fe-Co-B- (IVb group element,
In the (N, P) multi-phase amorphous soft magnetic thin film, the characteristic length of dispersion of the first amorphous phase mainly composed of Fe-Co, the volume ratio of each phase, etc. Although complicatedly changed, the essential induced magnetic anisotropy is determined by the composition ratio y, and this is clearly shown in FIG. This is a unique effect obtained by the research and development by the present inventors.

The macroscopic magnetic anisotropy of the soft magnetic thin film is obtained by the product of the number density of the transition metal element per unit space and the above-mentioned magnetic anisotropy energy ε _a. In order to obtain practically sufficient uniaxial magnetic anisotropy as a magnetic thin film, ε _a has a sufficient value in the range of y, that is, 0.10 <y in the composition of the sputtering target.
It is desirable to set the range to satisfy <0.33. Particularly, it is preferable because _a large ε _a can be obtained in the composition ratio range of 0.18 to 0.20.

The IVb group elements, N and P, are elements that form a second amorphous phase when used together with B as described above. Here, the value of z (composition ratio of B and (IVb group element, N, P)) may be set in a range satisfying 0 <z <1, but the second amorphous phase is stabilized. It is more preferable to set the range of 0.1 <z <0.6 in consideration of the effectiveness of the magnetic characteristics of the group IVb element. The IVb group element, N, P used is not particularly limited, but the use of C or the like makes it possible to use the IVb group element, N, P for the first amorphous phase.
Is preferable in that the addition amount of is limited to some extent.

By the way, as is clear from Hoffman's theory and the like, reduction of the amount of microcrystallization and dispersion of local magnetic anisotropy,
Appropriate macroscopic uniaxial magnetic anisotropy and appropriate exchange stiffness constant between magnetic particles are effective for obtaining soft magnetic properties.

In particular, the soft magnetic thin film obtained by the sputtering target for forming a soft magnetic thin film of the present invention is a Fe group having a general local magnetic anisotropy in the first amorphous phase due to a magnetostriction effect or the like. Larger than microcrystalline material. For this reason, the characteristic length of dispersion of the amorphous phase corresponding to the normal grain size and the thickness (width) of the second amorphous phase separating the first amorphous phase are important.

In the soft magnetic thin film obtained by the sputtering target for forming a soft magnetic thin film of the present invention, the thickness (width) of the second amorphous phase separating the first amorphous phase is about 3 nm or less, Good soft magnetic properties can be obtained. This makes it possible to achieve both soft magnetic properties and in-plane uniaxial magnetic anisotropy imparting and control. It is presumed that this is because the thickness of the second amorphous phase is sufficiently thin and a proper magnetic interaction between the adjacent first amorphous phases is ensured. Such an effect is attenuated at intervals of 3 nm or more. The average thickness of the second amorphous phase is preferably 5 nm or less. This is because the magnetic coupling region is reduced in a region beyond this and soft magnetic characteristics cannot be obtained due to the increase in coercive force.

The average thickness of the second amorphous phase is
Although the area ratio of each region does not change due to enlargement or reduction of the stereoscopic image of the microscope, it is not uniquely determined by the yield of each amorphous substance, but the region or grain of the second amorphous phase is not determined. Must be small enough.

The requirement for the thickness of the second amorphous phase is stricter than that of the Fe-based multiphase amorphous film.
Even if it is a region where isotropic soft magnetic characteristics are obtained in the base, F
In some cases, the e-Co group has a coercive force of 8000 A / m or more, and soft magnetic properties may not be obtained. This is probably because the local magnetic anisotropy is larger than that of the Fe group as described above. The thickness of the second amorphous phase of the Fe-based multiphase amorphous film described above is preferably set under the conditions described above with reference to the above values.

The soft magnetic thin film obtained by the sputtering target for forming a soft magnetic thin film of the present invention has an in-plane uniaxial magnetic anisotropy of an appropriate size, and imparts this in-plane uniaxial magnetic anisotropy. The control can be performed by various means as described above, and the method is not particularly limited.

The magnetic anisotropy is imparted and controlled by, for example, heat treatment in a magnetic field after film formation, film formation in a magnetic field, film formation in a high temperature magnetic field around 300 ° C., and a substrate having anisotropy in thermal expansion coefficient. It can be performed by room temperature film formation, high temperature film formation, low temperature film formation, introduction of strain into the substrate or soft magnetic thin film after film formation, and adoption of two or more of these methods.

Among these methods, a method suitable for controlling the uniaxial magnetic anisotropy while maintaining the soft magnetic property is heat treatment in a magnetic field. The heat treatment temperature suitable at this time varies depending on the film composition, but is preferably in the range of 530 to 620 k. According to such heat treatment in a magnetic field, TM between the transition metal (TM) and the metalloid atom (MD)
The structural anisotropy of the -MD pair is the main cause of induction of magnetic anisotropy.

In the amorphous phase-recovered soft magnetic thin film, Fe--C
a first amorphous phase mainly composed of o, B- (IVb group element,
The film in which the second amorphous phase mainly composed of (N, P) is finely dispersed is used to obtain the soft magnetic property that achieves both high resistivity and high saturation magnetization and to excite the high-frequency magnetization hard axis. It is a material suitable for controlling in-plane uniaxial magnetic anisotropy for the application of.

This makes it possible to obtain a soft magnetic thin film which is suitable for high operating frequencies, high efficiency, high energy density, high inductance density and the like of flat type magnetic elements. Such a planar magnetic element using the soft magnetic thin film obtained by the sputtering target for forming the soft magnetic thin film of the present invention is formed by laminating the above-mentioned soft magnetic thin film on one or both surfaces of the planar coil. It is suitable for flat inductance elements and flat transformers.

The sputtering target for forming a soft magnetic thin film of the present invention will be described in more detail below. First, as the texture in the sputtering target for forming a soft magnetic thin film of the present invention, a texture in which an Fe-Co alloy and Bx (IVb group element, N, P) are mixed, Fe and / or Co in B and / or Or, a structure in which x (IVb group element, N, P) forms a solid solution and / or a compound, Fe,
Co, B, x (IVb group element, N, P) exist independently, Fe, Co, B, x (IVb group element,
It is possible to obtain various tissues such as a tissue in which one or more of (N, P) are present. These organizations
Various selections can be made depending on the intended characteristics of the soft magnetic thin film. Among them, Fe and / or Co can be selected as B.
And / or a structure in which x (group IVb element) forms a solid solution and / or a compound is preferable.

Then, the sputtering target for forming a soft magnetic thin film of the present invention preferably has one or more of the following conditions. First of all, it is preferable that the magnetic permeability of the sputter target is uniform at least in the portion to be sputtered, and the magnetic permeability is small. As a result, the sputter rate increases, and uniform sputtering can be performed to obtain a uniform soft magnetic thin film. Preferably, the magnetic permeability is uniform over the entire surface of the sputter target, and the magnetic permeability is small.

Second, it is preferable that the sputter target has a small porosity, that is, a high density. As a result, the dust of the soft magnetic thin film after film formation can be reduced. Thirdly, it is preferable that the crystal grain size of the sputter target is small. As a result, it is possible to reduce the dust of the soft magnetic thin film after film formation and to obtain a soft magnetic thin film having a uniform composition and thickness.

Fourth, it is preferable that the surface roughness of the sputter target is small, at least in the portion to be sputtered. As a result, the dust of the soft magnetic thin film after film formation can be reduced. Preferably, the surface roughness on the entire surface of the sputter target is small.

Fifth, impurities in the sputter target,
Particularly, it is preferable that the gas component is small. Thereby, the soft magnetic characteristics can be improved. Here, as the form of the sputtering target for forming a soft magnetic thin film of the present invention, various forms can be adopted, for example, (1) raw material powder consisting of one kind or two or more kinds of each constituent element A sputter target manufactured by a powder metallurgy method, which is compounded to have a predetermined composition when viewed as one body. (2) A sputter target manufactured by a melting method in which the constituent elements are blended so as to have a predetermined composition when viewed as one body. (3) A sputter target manufactured by dividing a target piece composed of one kind or two or more kinds of each constituent element into a composite array, and adjusting the area ratio of each target piece to have a predetermined composition. . (4) A sputter target produced by blending the constituent elements so as to have a predetermined composition when viewed as one body, and spraying the composition on a sputter target substrate. Can be adopted.

As an example of the method for manufacturing the sputter target by the first powder metallurgy method, first, when the raw material powders made of one kind or two kinds or more of the respective constituent elements are integrally viewed, the predetermined composition is obtained. And mixed with a ball mill or the like to obtain a uniform mixed powder. At this time, by forming the material of the inner wall of the mixing device of the ball mill and / or the surface of the ball to be used or the material itself of one or more of the constituent elements, it is possible to prevent impurities from being mixed into the sputtering target. It becomes possible to reduce.

Then, this mixed powder is filled in a carbon mold and heated at a heating temperature of 900 by using a vacuum hot press.
Sintered body is obtained by pressure sintering under conditions of ℃ or higher and surface pressure of 200 kg / mm ² or higher. Alternatively, this mixed powder is filled in a molding die,
This is molded using wet-CIP or the like and then sintered to obtain a sintered body. In order to further densify the sintered body obtained by sintering after wet-CIP, it is preferable to further perform hot isostatic pressing (HIP).

Thereafter, the obtained sintered body is subjected to hot working such as forging and rolling as necessary for the purpose of increasing the size and densification, mechanical processing such as grinding, and further smoothing the surface by lapping if necessary. Into a sputter target having a predetermined shape.

The characteristics of the obtained soft magnetic thin film are influenced by the structure of the sputter target obtained by the first method. Therefore, in order to obtain the intended soft magnetic thin film, when manufacturing the sputter target of the present invention,
Each manufacturing condition such as the particle size of each raw material powder used, molding conditions, sintering conditions, and processing conditions can be appropriately selected.

Next, as an example of a method of manufacturing a sputter target by the second melting method, for example, first, the constituent elements are blended so as to have a predetermined composition when viewed as one body, and then directly mixed with an electron. An ingot is manufactured using a melting method such as linear melting. Alternatively, a sintered body having a predetermined composition when the respective constituent elements are viewed as one is obtained by a powder metallurgy method, and then an ingot is manufactured by a melting method such as electron beam melting.

Thereafter, if necessary, hot working such as forging and rolling is performed, mechanical processing such as grinding is performed, and if necessary, the surface is smoothed by lapping to obtain a sputter target having a predetermined shape.

The sputter target obtained by the first method or the second method is preferably manufactured integrally, in order to prevent dust from being generated during thin film formation. For the purpose, a plurality of identical sputter targets may be used in combination.
In this case, a plurality of combined sputter targets are fixed to the backing plate by brazing, etc., but the joints are spread to prevent the generation of dust from the joints of the targets, especially the edges. Joining or electron beam (EB) welding is preferable.

Here, as the diffusion bonding method, a direct bonding method, a bonding method in which one kind or two or more kinds of each constituent element are interposed in the bonding section, or one or two kinds of each constituent element is bonded to the bonding section. Various methods can be adopted, such as a method of joining by interposing a plating layer of at least one kind.

Next, as an example of a method of manufacturing a sputter target by adjusting the area ratio of each third target piece, for example, a target piece made of one or more kinds of each constituent element is powder metallurgy method. Alternatively, an ingot is manufactured by a melting method such as an electron beam (EB) melting method, the obtained ingot is machined if necessary, and then each ingot is divided to obtain target pieces, and the target pieces are combined. And the area ratio of each target piece is adjusted so that a predetermined composition is obtained. Then, if necessary, mechanical processing such as grinding is performed, and further, if necessary, the surface is smoothed by lapping to obtain a sputter target having a predetermined shape.

In this case, the characteristics of the obtained soft magnetic thin film are influenced by the structure of each target piece. Therefore, the manufacturing conditions of this target piece are appropriately selected. In the third method, because of the multiple arrangement,
In order to prevent generation of dust from the joint portion, particularly the edge portion, the joint portion is preferably diffusion-bonded or electron beam (EB) welded.

Here, as the diffusion bonding method, a direct bonding method, a bonding method in which one kind or two or more kinds of each constituent element are interposed in the bonding section, or one or two kinds of each constituent element is bonded to the bonding section. Various methods can be adopted, such as a method of joining by interposing a plating layer of at least one kind.

Next, as an example of the method for producing the sputtering target by the fourth thermal spraying, the constituent elements are blended so as to have a predetermined composition when viewed as one body,
After spraying the sputter target substrate, or individually preparing one or more of each constituent element, and simultaneously spraying the sputter target substrate, if necessary, further perform mechanical processing such as grinding, and further wrap the surface if necessary. To obtain a sputter target having a predetermined shape.

By adopting the various manufacturing methods as described above, the sputtering target for forming a soft magnetic thin film of the present invention can be obtained. The term "integrated" in the present invention means that the range is at least in the sputtered portion.

[0066]

【Example】

Example 1 First, an alloy sputtering target having a composition of Fe ₇₅ Co ₂₅ , a diameter of 127 mm and a thickness of 1 mm was manufactured by a melting method, and a B ₄ C chip obtained by a powder metallurgy method was placed on the sputtering target. A sputtering target having the composition specified in the present invention when viewed as a single body was obtained.

Using the obtained sputtering target, an Fe-Co-B-C type soft magnetic thin film was formed on the substrate by the RF magnetron sputtering method. At that time, the distance between the substrate and the sputter target is 170 mm,
The film forming conditions shown in Table 1 were used. The area ratio S _c
Is a film formation parameter in which the B ₄ C chip area S _B4C is standardized by the sputtering target erosion area S _erosion .

[0068]

[Table 1]

Under the above-mentioned film forming conditions, a film is formed for 5000 seconds,
A sample having a film thickness of 0.27 μm was obtained. As a pretreatment immediately before film formation, after the inside of the sputtering apparatus reached a predetermined degree of vacuum, pre-sputtering of a sputtering target (sputtering power: 400 W × 600 seconds) was performed.

The structure and characteristics of the soft magnetic thin film thus obtained were measured and evaluated in the following manner. The crystal structure (microstructure) of the soft magnetic thin film is specified by X-ray diffraction (thin film method: C
u-Kα ray, X-ray incident angle = 2.0 °) and transmission electron microscope observation. The composition ratio of the soft magnetic thin film is IPC
It was identified by optical emission analysis and high frequency heating / infrared absorption method. The thickness of the soft magnetic thin film is a stylus type surface roughness / film thickness meter.
The resistivity was measured by the 4-probe method (typical sample shape: 15 mm × 2 mm). The magnetic measurement was performed using a vibrating sample magnetometer (typical sample shape: 10 mm x 10 mm). Maximum applied magnetic field is 0.8
MA / m. The magnetization curve was measured in each of the easy magnetization axis direction and the hard magnetization axis direction. An external magnetic field was rotated in the film surface using a thin film magnetic torque meter, and the magnetic torque curve in the film surface was measured. The externally applied magnetic field is 0.8 MA / m. The obtained magnetic torque curve was Fourier-transformed and analyzed to determine the anisotropy constant K _U.

The observation result (micrograph) of the soft magnetic thin film obtained in Example 1 above by a transmission electron microscope is schematically shown in FIG. The X-ray diffraction peak is shown in FIG. Thus, an amorphous diffraction peak was obtained.

As is clear from FIGS. 1 and 2, Fe
Around the first amorphous phase (grain) 1 containing both Co and Co
It was confirmed that the second amorphous phase 2 containing both C and C had a film structure arranged in a mesh. It should be noted that arrow A in FIG. 1 indicates the easy magnetization axis direction of the macroscopic uniaxial magnetic anisotropy.

Hereinafter, in all the examples, the multi-phase amorphous phase was similarly confirmed. The full width at half maximum of the amorphous peak changed variously depending on the film forming conditions, but the peak position hardly changed.

The magnetization curve of the soft magnetic thin film obtained in this example is shown in FIG. Thus, in-plane uniaxial magnetic anisotropy was observed. 1.2T as saturation magnetization, 280 as resistivity
μΩcm was obtained. In addition, an in-plane uniaxial magnetic anisotropy energy of 4 × 10 ² J / m ³ was obtained. The composition ratio of the soft magnetic thin film was x = 0.26, y = 0.3, and z = 0.2. Further, the average thickness of the second amorphous phase separating the first amorphous phase 1 is about
It was 2.5 nm.

As described above, an amorphous soft magnetic thin film having both high resistivity and high saturation magnetization and in-plane uniaxial magnetic anisotropy can be obtained by the effect of the film forming conditions and the constituent elements.

Example 2 The thin film sample obtained in Example 1 was heat-treated in an in-plane DC magnetic field. Heat treatment temperature is 535K, heat treatment time is 1
The applied magnetic field was 0.8 MA / m for 0800 seconds, and the direction of the applied magnetic field was parallel to the easy axis of magnetization.

As a result, the in-plane uniaxial magnetic anisotropy changed only slightly and the coercive force decreased to 80 A / m or less. Thus, by performing so-called strain relief heat treatment, it is possible to obtain an amorphous soft magnetic thin film having a soft magnetic characteristic of high resistivity and high saturation magnetization without significantly affecting the magnetic anisotropy.

Example 3 Sputtering target B ₄ C chip area ratio S _c
An Fe—Co—B—C based soft magnetic thin film was formed on the substrate under the same film forming conditions as in Example 1 except that (= S _B4C / S _erosion ) was 0.24.

Under these film forming conditions, a film thickness of 3000 seconds was 0.22.
A sample having a film thickness of μm was obtained. This thin film sample has in-plane uniaxial magnetic anisotropy, saturation magnetization is 1.7 T, and resistivity is 220 μΩ.
It was cm. The composition ratio of the soft magnetic thin film is x = 0.25,
It was y = 0.2 and z = 0.31. In addition, the first amorphous phase 1
The average thickness of the second amorphous phase separating the layers was about 3.5 nm.

Example 4 Sputtering target B ₄ C chip area ratio S _c
Under the same film forming conditions as in Example 1, except that (= S _B4C / S _erosion ) was 0.31 and the Ar gas pressure during film formation was 0.27 Pa,
An Fe-Co-BC soft magnetic thin film was formed on the substrate.

Under these film forming conditions, a film formation of 4000 seconds gives 0.24
A sample having a film thickness of μm was obtained. This thin film sample has in-plane uniaxial magnetic anisotropy, saturation magnetization is 1.6 T and resistivity is 160 μΩ.
It was cm. In addition, a low coercive force of 39.6 A / m was obtained after in-plane uniaxial magnetic anisotropy and hard magnetization excitation after the soft magnetic thin film was formed. The composition ratio of the soft magnetic thin film is x = 0.
It was 26, y = 0.25, and z = 0.28. The average thickness of the second amorphous phase separating the first amorphous phase 1 was about 2.0 nm.

Example 5 An Fe—Co—B—C type soft magnetic thin film was formed on a substrate under the same film forming conditions as in Example 4 except that the film formation was performed in a DC magnetic field. The applied magnetic field direction was the direction in which the hard axis of magnetization was obtained at the stage after film formation. The direct current applied magnetic field was 55 kA / m.

The magnetization curve of the obtained thin film sample is shown in FIG. As is clear from FIG. 4, in-plane uniaxial magnetic anisotropy was induced in the applied magnetic field direction. In-plane uniaxial magnetic anisotropy is 3.5 ×
It was 10 ² J / m ³ . The resistivity and saturation magnetization were the same as in Example 4 within the range of measurement accuracy. As described above, by performing the film formation in the magnetic field, it becomes easy to give and control the in-plane uniaxial magnetic anisotropy.

Example 6 Three Si chips (10 mm × 20 mm) were formed on a sputter target.
An Fe-Co-BC-Si based soft magnetic thin film was formed on the substrate under the same film forming conditions as in Example 4 except that the number of additional sheets was increased.

Under these film forming conditions, the film formation for 4000 seconds is 0.25
A sample having a film thickness of μm was obtained. This thin film sample has in-plane uniaxial magnetic anisotropy, saturation magnetization 1.2T, resistivity 210 μΩ.
It was cm.

The magnetization curve of the obtained thin film sample is shown in FIG. As is clear from FIG. 5, in-plane uniaxial magnetic anisotropy was induced in the applied magnetic field direction. In-plane uniaxial magnetic anisotropy and 80A / m
A soft magnetic thin film having the following low coercive force and having both high saturation magnetization and high resistivity was obtained.

Example 7 A metal mask was formed so that 0.9 mm stripe soft magnetic thin films were arranged at 0.1 mm intervals, and film formation was performed under the same conditions as in Example 4. The stripe direction was set so that the easy axis of in-plane magnetization could be obtained at the stage after film formation.

As a result, an in-plane uniaxial magnetic anisotropy of 1.5 × 10 ² J / m ³ was obtained, and the easy axis of magnetization occurred in the direction parallel to the stripe. Uniaxial magnetic anisotropy caused by the multi-phase amorphous soft magnetic film itself at the stage after film formation has an effect of minimizing disorder of magnetic domains.

In this way, a control method applicable to general magnetic materials in general is provided by imparting induction of shape magnetic anisotropy applicable to general magnetic materials to the uniaxial magnetic anisotropy at the stage after film formation. You may use together.

Example 8 B ₄ C chip area ratio S _{c of the} sputtering target
(= S _B4C / S _erosion ) was changed variously, the Ar gas pressure during film formation was variously changed, and the other conditions were the film formation conditions of Example 1, and Fe—Co— on the substrate.
A BC soft magnetic thin film was formed. The thickness of the obtained thin film is
It was 0.2 to 0.3 μm.

With respect to the obtained sample, the heat treatment temperature was 573K,
Heat treatment was performed in a vacuum and DC magnetic field for a heat treatment time of 7320 seconds.
The applied magnetic field was 0.8 MA / m, and the degree of vacuum during heat treatment was 1 × 10 ^-2 Pa or less.

FIG. 6 shows an example of the uniaxial magnetization curve of the obtained sample. Thus, a uniform uniaxial magnetic anisotropy was obtained, and a sample showing an example of the hard axis of magnetization due to an ideal rotational magnetization process was obtained. Further, FIG. 7 shows anisotropic magnetic fields H _K of various samples. Furthermore, in these samples, the magnetic anisotropy energy ε _a per transition metal atom calculated from various analysis results such as FIG. 7 and the composition ratio was compared with the composition ratio (y value) of Fe—Co and B—C. The dissimilarity is shown in FIG. It can be seen from FIG. 8 that the composition ratio y has a great influence on the anisotropic energy in the sample groups in which the film forming conditions such as the Ar gas pressure and the B ₄ C chip area ratio S _c during film forming are variously different.

Comparative Example 1 Sputtering target B ₄ C chip area ratio S _c
The sputtering target with (= S _B4C / S _erosion ) of 0.08, the Ar gas pressure during film formation of 1 Pa, and the other film forming conditions of Example 1 were used. A thin film was formed. Under this film forming condition, a sample having a film thickness of 0.22 μm was obtained by forming a film for 2000 seconds.

When X-ray diffraction of this thin film sample was performed,
It was found that an α-Fe-based body-centered crystalline and amorphous mixed phase was obtained. In this sample, saturation magnetization 1.4T
, A resistivity of 350 μΩcm was obtained, but it is a mixed phase with crystalline. The coercive force was 9.98 kA / m, and excellent soft magnetic properties were not obtained.

Comparative Example 2 Sputtering target B ₄ C chip area ratio S _c
(= S _B4C / S _erosion ) was set to 0.24 and the Fe—Co—B—C type soft magnetic thin film was formed on the substrate under the film forming conditions of Example 1 except for the above. A sample having a film thickness of 0.23 μm was obtained by film formation for 3000 seconds under these film formation conditions.

As a result of X-ray diffraction and transmission electron microscope observation of this thin film sample, it was confirmed that a multi-phase amorphous film was obtained as in Example 1. However, the first Fe-Co group
The average thickness of the second amorphous phase separating the amorphous phases (grains) was about 5 nm. In this sample, the saturation magnetization 1.2
Although T and resistivity of 590 μΩcm were obtained, as shown in FIG. 9, the coercive force was 3.2 kA / m or more in any direction in the isotropic film, and the in-plane uniaxial magnetic anisotropy and excellent soft magnetic characteristics were obtained. Was not obtained.

Comparative Example 3 Sputtering target B ₄ C chip area ratio S _c
(= S _B4C / S _erosion ) was set to 0.16, the Ar gas pressure during film formation was set to 0.4 Pa, and the other conditions were the film formation conditions of Example 1, and Fe—Co—B—C was formed on the substrate.
A soft magnetic thin film was formed.

The thin film sample obtained was a mixed phase of crystalline and amorphous, and a multi-phase amorphous soft magnetic thin film was not obtained. The composition ratio was x = 0.25, y = 0.05, z = 0.3. Thus, if the value of y is too small, it is not possible to obtain a multiphase amorphous soft magnetic thin film.

Example 9 Under the same conditions as in Example 5, the thin film inductor 1 shown in FIG.
The magnetic film portion 1 (multi-phase amorphous soft magnetic thin film) 12 of No. 1 was produced, and thereafter heat-treated in a magnetic field under the same conditions as in Example 2. Here, the thin film inductor 11 shown in FIG. 10 is configured by laminating the multi-phase amorphous soft magnetic thin films 12 and 12 on both main surfaces of the double rectangular planar coil 13 by sputtering. In FIG. 10, reference numeral 14 is an electrode, arrow B indicates the easy axis of magnetization, and arrow B indicates the magnetic flux. The thin film inductor of this example showed a substantially flat inductance up to 50 MHz, and the quality factor Q was 10 or more, which was a good characteristic.

Example 10 By the melting method, first, the composition Fe (purity 99.9%), diameter 12
By manufacturing an Fe sputtering target having a thickness of 7 mm and a thickness of 1 mm and disposing a B ₄ C chip obtained by the powder metallurgy method on the sputtering target, the composition defined by the present invention is obtained when viewed as one body. A sputtering target was obtained.

An Fe-BC soft magnetic thin film was formed on the substrate by the RF magnetron sputtering method using the obtained sputtering target. At that time, Table 2
The film forming conditions shown in are used. The B ₄ C chip area ratio S _c (= S _B4C / S _erosion ) was set to 31%.

[0102]

[Table 2]

A sample having a film thickness of 0.2 μm was obtained under the above film forming conditions. As a result of observing the soft magnetic thin film obtained in Example 10 above with a transmission electron microscope, it was found that the Fe-rich first
And an amorphous phase of B-C rich second amorphous phase of
It was confirmed that the second amorphous phase was dispersed and arranged in a mesh shape around the first amorphous phase.

Further, this thin film sample has a saturation magnetization of 1.2 T.
The resistivity was 500 μΩcm. Moreover, it was confirmed that the film had in-plane uniaxial magnetic anisotropy at a stage after the formation of the soft magnetic thin film.

Among the film forming conditions in the above tenth embodiment,
A similar amorphous film was formed by variously changing the Ar gas pressure during film formation, and the saturation magnetic flux density and the resistivity thereof were measured. The results are shown in FIGS. 11 and 12. Further, FIG. 13 shows the relationship between the amount of B ₄ C chips and the coercive force.

As is clear from these figures, by controlling the A gas pressure during film formation, it is possible to obtain excellent soft magnetic characteristics in which both saturation magnetization and resistivity are compatible.
FIG. 14 shows the relationship between the Ar gas pressure and the coercive force during film formation.

As is clear from FIG. 14, Ar during film formation
It can be seen that uniaxial magnetic anisotropy can be obtained by controlling the gas pressure. Next, when a thin film inductor was constructed in the same manner as in Example 9 using the amorphous soft magnetic thin film according to this example, similarly good characteristics were exhibited.

Example 11 Fe _59.1 Co _21.4 B was used as a raw material powder composed of each constituent element.
_12.3 C _7.2 and Fe _57.6 Co _19.2 B _14.7 C _8.5 were blended and mixed by a ball mill to obtain a uniform mixed powder. Then, these mixed powders were filled in a carbon mold and pressure-sintered using a vacuum hot press to obtain an alloy sputtering target having a diameter of 5 inches and a thickness of 3 mm.

Using each of the obtained sputtering targets, a Fe-Co-B-C type soft magnetic thin film was formed on the substrate by the RF magnetron sputtering method. At that time, the distance between the substrate and the sputter target is 105 mm,
The film forming conditions shown in Table 3 were used.

[0110]

[Table 3]

Under the above-mentioned film forming conditions, a film is formed for 720 seconds,
A sample having a film thickness of 0.5 μm was obtained. As a pretreatment immediately before film formation, after the inside of the sputtering apparatus reached a predetermined vacuum degree, pre-sputtering of a sputtering target and substrate etching for the purpose of substrate cleaning were performed.

The soft magnetic thin films thus obtained were subjected to the shaking test as in Examples 1 to 10, and as a result, all of them have the same excellent soft magnetic characteristics as those of the Examples. It was

[0113]

As described above, the sputtering target for forming a soft magnetic thin film of the present invention achieves both high saturation magnetization and high resistivity and facilitates acquisition of high frequency permeability by hard axis excitation. A magnetic thin film can be obtained. As a result, it can greatly contribute to miniaturization and high performance of the planar magnetic element.

[Brief description of drawings]

FIG. 1 is a diagram systematically showing the microstructure of a multi-phase amorphous soft magnetic thin film in Example 1.

FIG. 2 is an X of the multi-phase amorphous soft magnetic thin film in Example 1.
It is a figure which shows a line diffraction pattern.

FIG. 3 is a diagram showing a magnetization curve of a multi-phase amorphous soft magnetic thin film in Example 1.

FIG. 4 is a diagram showing a magnetization curve of a multi-phase amorphous soft magnetic thin film in Example 5.

5 is a diagram showing a magnetization curve of a multi-phase amorphous soft magnetic thin film of Example 6. FIG.

FIG. 6 is a diagram showing an example of a uniaxial magnetization curve of a multi-phase amorphous soft magnetic thin film in Example 8.

7 is a diagram showing an anisotropic magnetic field of various multi-phase amorphous soft magnetic thin films in Example 8. FIG.

FIG. 8 is a diagram showing the composition ratio y dependence of the magnetic anisotropy energy ε _a per atom of a transition metal in the multi-phase amorphous soft magnetic thin film of Example 8.

9 is a diagram showing a magnetization curve of an amorphous soft magnetic thin film in Comparative Example 2. FIG.

10A and 10B are diagrams showing a configuration of a thin film inductor manufactured in Example 9, wherein FIG. 10A is a plan view thereof, and FIG. 10B is a sectional view taken along line XX thereof.

FIG. 11 is a diagram showing an example of a relationship between Ar gas pressure and saturation magnetic flux density during film formation in Example 10.

FIG. 12 is a diagram showing an example of a relationship between Ar gas pressure and resistivity during film formation in Example 10.

13 is a diagram showing an example of the relationship between the amount of B ₄ C chips and coercive force during film formation in Example 10. FIG.

FIG. 14 is a diagram showing an example of a relationship between Ar gas pressure and coercive force during film formation in Example 10.

[Explanation of symbols]

 1 First amorphous phase containing both Fe and Co 2 Second amorphous phase containing both B and C 11 Thin film inductor 12 Multi-phase amorphous soft magnetic thin film 13 Double rectangular planar coil

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H01F 41/18 H01F 41/18 (72) Inventor Tetsuhiko Mizoguchi Toshiba Komukai Toshiba, Kawasaki City, Kanagawa Prefecture Town No. 1 Toshiba Corporation Research & Development Center

Claims (1)

[Claims] 1. When viewed as a unit, the following general formula: (Fe _1-x Co _x ) _1-y (B _1-z X _z ) _y (where x is a group IVb element, N, P) Indicates one or more elements selected, and x, y, and z are each 0 ≦ x
≦ 0.5, 0.06 <y <0.5, and 0 <z <1), the soft magnetic thin film forming sputtering target.