JP7181064B2 - FERROMAGNETIC LAMINATED FILM AND MANUFACTURING METHOD THEREOF AND ELECTROMAGNETIC INDUCTIVE ELECTRONIC COMPONENTS - Google Patents

Description

The present invention relates to a ferromagnetic laminated film having a structure in which ferromagnetic layers are laminated with an insulating layer sandwiched between them. It is characterized in that it can be controlled simply by pressing the button.

Laminated films with different magnetic layer thicknesses per layer are continuously formed in one film, and the ratio of the total thickness of each magnetic layer and the order of lamination determine the complex magnetic permeability μ (=μ'-jμ″). It is characterized by being able to control the superposition and the magnetic permeability ratio, and to control the frequency and bandwidth at which the magnetic loss term μ″ becomes large.

It is characterized by being able to control the frequency and bandwidth at which the magnetic loss term μ″ increases significantly by changing the thickness of the magnetic layer per layer of each laminated film and the film composition.

As the fifth generation mobile communication uses the SHF band (3 to 30 GHz), there is a demand in the industrial world for inductor materials and electromagnetic noise suppression materials suitable for this. For example, it is said that eddy current loss is dominant in the noise suppression effect of large-area films at high frequencies. The depth d is represented by the relational expression (1) using the specific resistance ρ of the magnetic film. As is clear from the relational expression (1), the higher the relative permeability μ, the smaller the skin depth d.

d=(ρ/πfμ) ^1/2 (1).

The eddy current loss P _e when a magnetic field with a magnetic flux density B is applied to a magnetic film having a thickness t is expressed by the relational expression (2). The specific resistance ρ of the magnetic film is usually higher than that of the metal film, but as is clear from the relational expression (2), the larger the specific resistance ρ, the smaller the eddy current loss P _e .

P _e =(πtfB) ² /6ρ (2).

Skin depth _d and eddy current loss P _e have a trade-off relationship with respect to resistivity ρ. . Furthermore, when the film thickness t exceeds the skin depth d, the influence of the eddy current loss P _e becomes significant. Ideally, t should be one-third or less of d in order to use it for low-loss inductors. On the other hand, the effect of magnetic loss due to the magnetic permeability μ is added to the electrical noise suppression effect. For this reason, although the specific resistance ρ is higher than that of metal, the noise suppression effect due to eddy current loss of a magnetic film having a high magnetic permeability μ is generally higher than that of metal, and is said to have frequency selectivity. In addition, the noise suppression effect due to the magnetic loss itself is superimposed and taken into account.

Both the eddy current loss and the magnetic loss depend on the frequency characteristic of the complex magnetic permeability μ. Here, there is uniaxial anisotropy in the film plane, and the calculation results of the high-frequency magnetic permeability in the difficult-to-magnetize direction are shown in FIGS. 8A and 8B. According to the calculation results shown in FIG. 8A, the dispersion of anisotropy is small, and the imaginary part (loss) of the complex permeability μ″ ( double-dot chain line ) rises sharply around the natural resonance frequency. According to the calculation results shown in FIG. 8B, the anisotropic dispersion is large, and the imaginary part μ″ of the complex permeability changes gently around the natural resonance frequency at which it is maximized. Electromagnetic induction components such as inductors that use the real part μ' ( chain line ) of complex magnetic permeability, and filters for absorbing noise at a specific frequency, have a sharp rise in the imaginary part μ” of magnetic permeability. The loss in the frequency band should not be high.

However, when considered as a noise suppression material, the band of FIG. If the material properties of 8B are used, the rise of μ” is slow. In some cases, the "foot" attenuates even the first-order component of the main signal.

In other words, as a noise suppression material, as shown in FIG. It is considered desirable to have a rectangular frequency characteristic that maintains , and is commercially available as a noise suppression sheet (see, for example, prior art document 2).

In order to prevent the magnetic flux from propagating too far through the magnetic material, the noise suppressing material must not have an excessively high magnetic permeability μ, must not have an excessively high or low resistivity ρ, and must not have an excessively high or low natural resonance frequency. A corresponding feature is that the effect occurs in the high frequency band (see, for example, Patent Document 1). Of the impedance Z of the device, the AC resistance R (Z = R + jX), which becomes a loss, is related to the imaginary term μ″ (μ = μ'-jμ”) of the complex permeability as shown in the relational expression (3). Also due to S is the magnetic path cross-sectional area of the device, N corresponds to the number of turns of the coil, and l is the magnetic path length of the device.

R=μ″SN/l (3).

JP 2017-041599 A JP 2007-287840 A

FIG. 9 shows a cross-sectional STEM (scanning transmission electron microscope) of a nanogranular thin film 10 having a composition of (Co _0.69 Pd _0.31 ) ₅₂ (Ca _0.33 F _0.67 ) ₄₈ formed on a substrate 10 by a tandem method (described later). Electron microscope) observation images are shown. The nanostructure of the initial layer near the interface with the substrate 10 (the layer whose distance from the substrate is, for example, within 100 nm) (see the enlarged image (lower right) in the frame R1 of FIG. 9 ) and the substrate rather than the initial layer It is different from the nanostructure of the main layer which is spaced apart from 10 (see enlarged image in frame R2 of FIG. 9 (upper right)).

In the region where the magnetic particles (L) increase in the film composition and become ferromagnetic, the shape of the granules changes from a sphere to a spheroid. This longitudinal direction corresponds to the crystallographic direction of easy magnetization. In the main layer, the longitudinal direction of the granules is tilted from the film thickness direction to the in-plane direction, and crystal orientation is observed (the direction in which the granules are tilted is biased). In-plane uniaxial anisotropy is more likely to be obtained than a ferromagnetic film having a nanogranular structure (hereinafter referred to as the “conventional film”), and loss is reduced, resulting in a large anisotropic magnetic field. will be improved.

In the initial layer, the longitudinal direction of the granules is oriented in the film thickness direction, and the structure is similar to that of the conventional film. and (2) the anisotropic magnetic field is low, which is difficult to apply unless the film is formed in a magnetic field.

Therefore, if the film thickness is reduced, the effect of the initial layer increases, and since the nanogranular thin film has a high specific resistance in the first place, it is not affected by eddy current loss even if it is thick within a practical film thickness range. Therefore, (1) higher magnetic permeability (not recovery from deterioration of eddy current loss), (2) lower frequency (not recovery from deterioration of eddy current loss), (3) lower coercive force (same as metal magnetic film effect) and (4) reduction of anisotropic dispersion (same effect as metal magnetic film).

Accordingly, it is an object of the present invention to provide a ferromagnetic thin film or the like capable of enhancing the effects of a ferromagnetic thin film having a nanogranular structure, such as a high magnetic permeability.

The ferromagnetic laminated film of the present invention has the general formula L _1-ab M _a F _b (L: one or more elements selected from Fe, Co and Ni (excluding Ni alone), or and one or more ferromagnetic elements selected from Ni and one or more noble metal elements selected from Pd and Pt (the atomic ratio of the noble metal elements in the alloy is 0.50 or less), M : one or more elements selected from Li, Mg, Al, Ca, Sr, Ba, Gd and Y, F: fluorine, 0.03≤a≤0.07, 0.06≤b≤0.18, 0.10≦a+b≦0.24), and a nanogranular structure in which magnetic particles represented by L and having an average particle size of 1 to 20 nm are uniformly distributed in an insulating matrix made of M fluoride. and an insulating layer having a composition represented by the general formula M _c F _d (1≦c≦2, 1≦d≦3).

The ferromagnetic laminated film of the present invention has a structure in which the plurality of ferromagnetic layers including the first ferromagnetic layer formed on a substrate are laminated via the insulating layer, and the plurality of ferromagnetic layers The layers comprise one or more first ferromagnetic layers having a thickness within a first thickness range and a second thickness range having a lower limit greater than the upper limit of said first thickness range. and one or more second ferromagnetic layers having a thickness comprised between .

A ferromagnetic laminated film manufacturing method of the present invention includes the steps of fabricating the first ferromagnetic layer, fabricating the second ferromagnetic layer, and fabricating the insulating layer. Each of the step of fabricating the first ferromagnetic layer and the step of fabricating the second ferromagnetic layer consists of L which is one or more elements selected from Fe, Ni and Co (excluding Ni alone). Alternatively, a first cathode comprising one or more ferromagnetic elements selected from Fe, Co and Ni and one or more noble metal elements selected from Pd and Pt, and Li, Mg, Al, Ca , Sr, Ba, Gd and Y. and rotating the anode to periodically move the substrate supported by the anode to a position where the sputtered particles emitted from each of the first cathode and the second cathode are incident. and the step of producing the insulating layer includes the step of generating sputtered particles from the second cathode by controlling the power supplied to the second cathode; positioning the substrate at a position where sputtered particles emitted from the second cathode are incident.

According to the ferromagnetic laminated film of the present invention, one or more first ferromagnetic layers consisting of or including an initial layer having a thickness within a first thickness range, and a second thickness By stacking one or more second ferromagnetic layers consisting of or including an initial layer and having a thickness within the range, the electromagnetic properties of the stacked film of the first ferromagnetic layer and the electromagnetic characteristics of the laminated film of the second ferromagnetic layer. The thickness of the ferromagnetic layer having a nanogranular structure is greatly affected by the initial layer (the layer in which the longitudinal direction of the granules is oriented in the film thickness direction), especially the initial layer in the first ferromagnetic layer formed on the substrate. adjusted to be

As a result, (1) high magnetic permeability (not recovery from deterioration of eddy current loss), (2) reduction in frequency (not recovery from deterioration of eddy current loss), (3) reduction in coercive force (metal magnetic film and (same effect) and (4) reduction of anisotropic dispersion (same effect as the metal magnetic film). Since the effect is different depending on the electromagnetic characteristics of the stacked films of the second ferromagnetic layer and the second ferromagnetic layer, μ″ with different natural resonance frequencies are superimposed and the resonances are relaxed and connected to maintain a high value.

FIG. 2 is a configuration explanatory diagram of a ferromagnetic multilayer film as a first embodiment of the present invention; FIG. 4 is an explanatory view relating to the method for manufacturing a ferromagnetic laminated film of the present invention; FIG. 4 is an explanatory diagram regarding the frequency dependence of the complex magnetic permeability of a ferromagnetic laminated film (reference example 1). FIG. 4 is an explanatory diagram regarding the frequency dependence of the complex magnetic permeability of a ferromagnetic laminated film (reference example 2). Explanatory drawing about the prediction calculation result of the frequency dependence of the complex magnetic permeability of a ferromagnetic laminated film. FIG. 4 is an explanatory diagram regarding the frequency dependence of the complex magnetic permeability of a ferromagnetic laminated film (Example 1). FIG. 4 is an explanatory diagram regarding the frequency dependence of what corresponds to the AC resistance (real part of impedance) of the ferromagnetic laminated film (Example 1). A cross-sectional TEM image of a ferromagnetic laminated film (reference example). FIG. 4 is an explanatory diagram of the structure of a ferromagnetic multilayer film as a second embodiment of the present invention; FIG. 4 is an explanatory diagram regarding the frequency dependence of the complex magnetic permeability of a ferromagnetic laminated film (Example 2). There is uniaxial anisotropy in the film plane, and the calculation result of the high-frequency magnetic permeability in the direction of difficult magnetization (when the anisotropic dispersion is small). There is uniaxial anisotropy in the film plane, and the calculation result of the high-frequency magnetic permeability in the direction of difficult magnetization (when the anisotropic dispersion is large). Explanatory drawing about the nanostructure of a nanogranular thin film. FIG. 10 is an explanatory diagram of the structure of a ferromagnetic multilayer film as a third embodiment of the present invention; FIG. 4 is an explanatory diagram of the frequency dependence of the complex magnetic permeability of a ferromagnetic laminated film (Example 3). FIG. 11 is an explanatory diagram regarding the frequency dependence of what corresponds to the AC resistance (real part of impedance) of the ferromagnetic laminated film (Example 3).

(First embodiment)
(Constitution)
The ferromagnetic multilayer film as the first embodiment of the present invention shown in FIG. A magnetic layer 212 and two second ferromagnetic layers 221 and 222 have a four-layer structure in which the insulating layer 30 is sandwiched between them. Hereinafter, the first ferromagnetic layers 211 and 212 and the two second ferromagnetic layers 221 and 222 are simply referred to as the ferromagnetic layer 20 when referring without distinction.

The ferromagnetic layer 20 has a composition represented by the general formula L _1-ab M _a F _b . "L" is one or more elements selected from Fe, Co and Ni (excluding Ni alone), or one or more ferromagnetic elements selected from Fe, Co and Ni, Pd and It is an alloy with one or more noble metal elements selected from Pt (the atomic ratio of the noble metal elements in the alloy is 0.50 or less). "M" is one or more elements selected from Li, Mg, Al, Ca, Sr, Ba, Gd and Y; "F" is fluorine. The atomic ratios a and b are 0.03≦a≦0.07, 0.06≦b≦0.18, and 0.10≦a+b≦0.24.

Of the components L of the ferromagnetic layer 20, Ni has a low saturation magnetization, so these metals alone are excluded from L. Therefore, L may be Co alone, Fe alone, Co--Fe, Co--Ni, Co--Ni--Fe, or the like. When a is less than 0.03 and/or when b is less than 0.06, the specific resistance ρ of the ferromagnetic layer 20 becomes excessively small (for example, 1.0×10 ² μΩ·cm or less). When a is greater than 0.07 and/or when b is greater than 0.18, both the saturation magnetization and the anisotropic magnetic field of the ferromagnetic layer 20 are reduced, and a single layer film of about 1000 nm can be used in the GHz band (for example, 7 GHz). It becomes difficult to obtain the natural resonance frequency of (above).

Specifically, in LMF, when the total atomic ratio (a+b) of M and F is 0.25 or more, the contact of granules made of metal L decreases and the specific resistance increases ( For example, reaching 1×10 ³ μΩ·cm or more), the magnetic coupling between the granules is reduced, and the anisotropy field is also reduced due to the reduced long-range permeability of magnetocrystalline anisotropy. The magnetization is diluted simply by reducing the space occupation ratio of the magnetic material. Furthermore, in the composition region where the total atomic ratio of M and F increases and exceeds 0.60, the distance between the granules made of the metal L increases, so that the granules that are magnetically coupled almost disappear, and the ferromagnetism of the film is lost (superparamagnetism). "Ferromagnetism" also includes "speromagnetic ordered state", which partially includes "superparamagnetism", which means that the granule density of the nanogranular film is reduced and it is no longer ferromagnetic, but to the extent possible Therefore, the magnetic metal granules should be densely packed.

Therefore, in the ferromagnetic layer 20, in a composition range in which the total atomic ratio (a+b) of M and F is 0.24 or less, in other words, the atomic ratio (1−(a+b)) of L is 0.76 or more, especially Anisotropic magnetic field and saturation magnetization are increased. However, when the atomic ratio of L exceeds 0.90 or the total atomic ratio of M and F is 0.10, although the magnetic properties of the ferromagnetic layer 20 are improved, the specific resistance is significantly reduced (for example, 1.0×10 ² μΩ·cm), and there is no difference from conventional metal materials in terms of eddy current loss. When the magnetization is small (for example, less than 3.5 kG) and only the anisotropic magnetic field is high, the static magnetic permeability is less than 2, and air as a functional material (electromagnetic field propagating material, etc.) in device applications. It becomes difficult to distinguish between Also, if the magnetization is too large (for example, exceeding 21.5 kG), the specific resistance ρ of the ferromagnetic layer 20 becomes low (for example, below 1.0×10 ² μΩ·cm).

The ferromagnetic layer 20 has a nanogranular structure in which magnetic particles (granules) represented by L and having an average particle size of 1 to 20 nm are uniformly distributed in an insulating matrix made of M fluoride. It is required that the granules are spaced close enough to or touching that exchange interactions occur. When the granules come into contact with each other, they are also magnetically coupled. Therefore, macroscopically, the current path passing through the nanogranular film must be electrically separated to some extent by an insulator. When the spacing between granules is wider than about 1 nm, both the magnetic interaction between granules and electron tunneling through the insulator due to the quantum effect occur simultaneously. The specific resistance of a substance exhibiting electric conduction by tunnel conduction is higher than that of metallic conduction. However, since the insulating property inherent to the insulator is significantly impaired, it is important to select a material that has particularly excellent inherent insulating property. Fluoride insulators achieve high specific resistance in order to limit the current path even under conditions of tunnel conduction at a distance of about 1 nm or more that causes magnetic coupling, or metallic conduction due to contact, for the reasons described later. be able to.

In order to magnetically couple the granules together, it is necessary to increase the total volume of the granules, in other words, the packing density of the granules, which increases the amount of metal in the thin film. In this case, the ferromagnetism is enhanced and a high natural resonance frequency can be achieved, but the amount of insulator is relatively reduced, so the specific resistance is lowered. This decrease in specific resistance can be overcome by using a fluoride insulator, which will be discussed below, as the matrix material of the granules so that it does not fall below that of conventional metallic materials.

In the mechanism (random anisotropy) in which the nanostructured magnetic material produces soft magnetism due to the reduction in effective magnetocrystalline anisotropy, the anisotropic magnetic field is reduced while exhibiting soft magnetism. However, nanogranular materials can have a certain crystal orientation, unlike typical nanostructured soft magnetic materials. In other words, it is effective to use a magnetic metal with high magnetocrystalline anisotropy for the granules.

A nanogranular structure containing fluoride crystals has a high resistivity. The reason for this is that fluorides such as MgF ₂ and CaF ₂ have larger energy band gaps than oxides such as Al ₂ O ₃ (CaF ₂ : 12.1 eV, MgF ₂ : 11.8 eV, Al ₂ O ₃ :9 eV, all values for a single crystal), and the resistivity is increased. A feature of the nanogranular structure film using fluoride is that the fluoride forms a crystal structure, unlike the case of using nitride or oxide. The crystalline structure means that the composition is stable near the stoichiometric composition, there is no reduction in the bandgap unlike materials with an amorphous structure, and furthermore, it is compatible with the metal that constitutes the granules during the production of the material. Since the mixing of fluoride is suppressed, it is possible to achieve a very high level of electrical resistance compared to the conventional art. In addition, if such an insulator is used, conventional oxides and nitrides can be used as matrix materials even in materials with a metallic amount in the region where the contact between granules increases and the specific resistance decreases. The resistivity is relatively high compared to conventional nanogranular ferromagnetic films.

Co is a material with a high magnetocrystalline anisotropy constant of the order of 10 ⁷ erg/cm ³ even by itself in the case of a hexagonal close-packed crystal structure. Fe and Ni also have crystal anisotropy on the order of 10 ⁵ erg/cm ³ although weaker than Co. However, it is a well-known fact that there are combinations in which the anisotropy is not simply weakened but rather strengthened when Fe or Ni is dissolved in Co. It is also known that when the noble metals Pt and Pd are dissolved in the above magnetic metal, anisotropy of 10 ⁶ to 10 ⁷ erg/cm ³ , which is dramatically increased, can be obtained. . Thus, by selecting a highly anisotropic granular metal composition, the anisotropic magnetic field of the nanogranular film having crystal orientation can be increased.

By making the magnetic metal granules an alloy containing a chemically extremely stable Pd or Pt noble metal, the anti-fluoridation property of the magnetic metal granules can be enhanced and phase separation from the fluoride matrix can be promoted. . If the element of L constituting the magnetic metal granules is combined with F, the saturation magnetization of the film is reduced, but Pd and Pt have the effect of minimizing this. Furthermore, since Pd and Pt have the effect of significantly increasing the anisotropic magnetic field, Ni alone can also be used. However, since Pd and Pt are non-magnetic metals, when their atomic ratio exceeds 50%, although the anisotropy becomes strong, the saturation magnetization decreases. The resonance frequency does not extend to the high frequency side, and the magnetostriction constant and cost increase significantly, which is not preferable.

Each of the thickness t 211 of the first ferromagnetic layer ₂₁₁ and the thickness t ₂₁₂ of the first ferromagnetic layer 212 is designed to fall within a first thickness range. The first thickness range is, for example, a thickness range of 20-100 nm, 50-200 nm, 100-200 nm. The first thickness range may be an unavoidable error range (eg, 40 to 60 nm) from the viewpoint of film thickness control accuracy, with the target thickness (eg, 50 nm) as a reference.

Each of the thickness t 221 of the second ferromagnetic layer ₂₂₁ and the thickness t _{222 of the second ferromagnetic layer 222} is in a second thickness range having a lower limit greater than the upper limit of the first thickness range. include. The second thickness range is, for example, a thickness range of 200-800 nm, 400-1000 nm, 500-2000 nm. The second thickness range may be an unavoidable error range (eg, 490 to 510 nm) from the viewpoint of film thickness control accuracy, with the target thickness (eg, 500 nm) as a reference.

By designing the thickness of the ferromagnetic layer 20 to be about the same as the initial layer, the influence of the portion having the same nanostructure as the initial layer (see the enlarged image (lower right) in the frame R1 of FIG. 2) becomes larger (than the nanostructure of the main layer (see the enlarged image (upper right) in frame R2 of FIG. 2)).

The insulating layer 30 has a composition represented by the general formula M _c F _d (1≤c≤2, 1≤d≤3). The thickness t ₂₁ of the insulating layer 30 is designed to fall within the range of 2-50 nm. This is because the ferromagnetic layer 20 is not exchange-coupled through the insulating layer 30 in the thickness direction but is coupled at each end of the ferromagnetic layer 20 without breaking the insulating layer 30 .

(Manufacturing method of ferromagnetic laminated film)
A method of manufacturing a ferromagnetic laminated film (see FIG. 1) as a first embodiment of the present invention will be described with reference to FIG. The method includes forming a first ferromagnetic layer 211 , an insulating layer 30 , a first ferromagnetic layer 212 , an insulating layer 30 , a second ferromagnetic layer 221 , an insulating layer 30 and a second ferromagnetic layer 222 on the substrate 10 . It includes a step of fabricating so as to laminate in order.

(1) The step of fabricating the ferromagnetic layer 20 includes (1-1) independently controlling the power supplied to each of the first cathode 41 and the second cathode 42 arranged in the chamber 40 so that the first cathode 41 and (1-2) rotating the anode 44 to rotate the substrate 10 supported by the anode 44 to the first cathode 41 and the second cathode 42, respectively. and periodically passing through a location where the sputtered particles emitted from the are incident.

As the substrate 10, for example, about 0.15 mm thick cover glass, about 0.2 mm thick Schott D263 (trade name of Shot) glass, and about 0.3 mm thick Corning Eagle XG (Corning (trade name) glass, a 0.5 mm-thick Si wafer whose surface is thermally oxidized, 0.5 mm-thick quartz glass, or similarly about 0.5 mm-thick MgO and sapphire are used.

The first cathode 41 is made of L, which is one or more elements selected from Fe, Ni and Co (excluding Ni alone). In addition, the first cathode 41 may contain at least one ferromagnetic element selected from Fe, Co and Ni, and at least one noble metal element selected from Pd and Pt. The second cathode 42 is composed of a fluoride of M, which is one or more elements selected from Li, Mg, Al, Ca, Sr, Ba, Gd and Y.

(2) The step of producing the insulating layer 30 includes (2-1) generating sputtered particles from the second cathode 42 by controlling the power supplied to the second cathode 42, and (2-2) the anode 44. and positioning the substrate 10 at a position where sputtered particles emitted from the second cathode 42 are incident by controlling the rotation angle of the substrate 10 .

In FIG. 2, the first cathode 41 and the second cathode 42 are held downward, and the anode 44 is held upward, so that the cathodes 41, 42 and the anode 44 are arranged to face each other. Alternatively, the cathodes 41 and 42 and the anode 44 may be arranged facing each other by holding the first cathode 41 and the second cathode 42 upward and holding the anode 44 downward. The cathodes 41 and 42 and the anode 44 may be arranged facing each other by holding the first cathode 41 and the second cathode 42 sideways and holding the anode 44 sideways. The cathodes 41, 42 and the anode 44 may be arranged non-opposing.

The materials forming each of the first cathode 41 and the second cathode 42 are sputtered, and the sputtered particles, which are partially free-radicalized, fly out of each cathode 41 , 42 . Sputtered particles having a negative charge are electrically attracted to the anode 44, and the first ferromagnetic layer 211, the insulating layer 30, the first ferromagnetic layer 212, the insulating layer 30, the second ferromagnetic layer 221, the insulating layer 30 and the A second ferromagnetic layer 222 is fabricated in order to be laminated on the substrate 10 .

The power applied to the first cathode 41 and the second cathode 42 is independently supplied by the first power supply 410 and the second power supply 420, respectively, such that the material of each cathode 41, 42 corresponds to the composition of the layer. controlled by Sputtered particles simultaneously sputtered from the first cathode 41 and the second cathode 42 reach the substrate 10 supported by the anode 44 to form a layer of desired composition. A film having a desired composition is formed by periodically passing the substrate 10 through positions near the first and second cathodes. In order to control the incident angle of sputtered particles, the cathodes 41, 42 or the substrate 10 are arbitrarily angled within the range in which the magnetic anisotropy derived from the film structure is maintained, and the cathodes 41, 42 and the anode 44 face each other. Placement relationships may be controlled. Similarly, in the non-facing arrangement, a film having a desired composition is formed by periodically passing the position where the substrate 10 comes into contact with the sputtered particles.

The anode 44 is rotationally driven, for example, at a constant or variable rotation speed within the range of 1 to 200 rpm, and a peripheral speed (rotational force) corresponding to the rotation speed is applied in the plane of the substrate 10, thereby performing sputtering. Uniaxial orientation occurs in the ferromagnetic layer 20 without a magnetic field applied therein. A magnetic field in the range of 100-500 Oe may be applied to the substrate 10 in the direction imparted anisotropy by the rotation of the anode 44, further enhancing the anisotropy of the ferromagnetic layer 20. FIG.

Pure Ar gas, for example, is used as the sputtering gas. The Ar gas pressure forming the atmosphere of the substrate 10 is controlled within a pressure range of 1 to 20 mTorr. The sputtering power from each of the first power supply 410 and the second power supply 420 is controlled to 10-1000W. The thickness of the layer is adjusted depending on the film formation time. The substrate 10 is indirect water cooled or controlled to a predetermined temperature within the temperature range of 100-800.degree. A static magnetic field of 100 to 500 Oe may be applied to the substrate 10 by arranging a pair of permanent magnets on the substrate holder.

The step (1) or the steps (1) and (2) are performed in a static magnetic field or in a non-magnetic field. The substrate 10 may be heated to a predetermined temperature within a temperature range of 100 to 800° C. by a heater (not shown). Each of the first ferromagnetic layer 11 and the second ferromagnetic layer 12 is heated to a temperature range of 100 to 800° C. during and/or after fabrication, for example, in a static magnetic field, a rotating magnetic field, or in no magnetic field. The heat treatment is performed by being held at a predetermined temperature included for a predetermined period of time included in the time range of, for example, 5 minutes to 5 hours. In-film uniaxial anisotropy is imparted to each ferromagnetic layer 20 by both the manufacturing process and the heat treatment process of each ferromagnetic layer 20 . The anisotropic magnetic field in each ferromagnetic layer 20 can be controlled by heat treatment in a static magnetic field of 300 Oe to 10 kOe or in a rotating magnetic field. If the heat treatment temperature is lower than 100° C., there is almost no difference from the heat generated during the fabrication of each layer, so there is no effect. be.

Magnetic anisotropy is induced by applying a static magnetic field during film formation, such as by arranging an electromagnet or permanent magnet near the substrate 10, and uniaxial anisotropy is strengthened by rotating the substrate 10. By doing so, a thin film having desired magnetic properties can be obtained.

(Evaluation of ferromagnetic laminated film)
(Example 1)
A ferromagnetic laminated film of Example 1 was produced according to the first embodiment. In Example 1, the ferromagnetic layer 20 has a composition represented by (Co _0.84 Pd _0.16 ) _0.82 -(Ca _0.33 F _0.67 ) _0.18 . The insulating layer 30 has a composition represented by _CaF2 . The thickness t212 of the thicknesses _t211 and 212 of the first ferromagnetic layers 211 is designed to be 50 nm, the thickness _t222 of the thicknesses _t221 and 222 of the second ferromagnetic layers ₂₂₁ is designed to be 500 nm, and the insulating layer The thickness of 30 was designed to be 10 nm.

In order to predict the frequency dependence of the complex permeability of the ferromagnetic laminated film of Example 1, two ferromagnetic layers 20 (corresponding to the first ferromagnetic layers 221 and 222) having a thickness of 500 nm were formed on the substrate 10. is laminated with an insulating layer 30 interposed between the ferromagnetic laminated film of Reference Example 1 and two ferromagnetic layers 20 with a thickness of 50 nm on the substrate 10 (second ferromagnetic layers 211 and 212 ) was laminated with an insulating layer 30 interposed therebetween to form a ferromagnetic laminated film of Reference Example 2 having a two-layer structure.

FIG. 3A shows the measurement result of the frequency dependence of the complex magnetic permeability of only the ferromagnetic laminated film of Reference Example 1. FIG. FIG. 3B shows the measurement result of the frequency dependence of the complex magnetic permeability of only the ferromagnetic laminated film of Reference Example 2. As shown in FIG. FIG. 3C shows the prediction of the frequency dependence of the complex permeability (real part) μ′ as a synthesis result of the measurement results of the frequency dependence of the complex permeability of the ferromagnetic laminated films of Reference Examples 1 and 2. A one-dot chain line indicates the calculation result, and a two-dot chain line indicates the predicted calculation result of the frequency dependence of the complex permeability (imaginary part) μ″.

It can be seen from FIG. 3A that the complex magnetic permeability (imaginary part) μ″ of the ferromagnetic multilayer film of Reference Example 1 shows a peak near f=7.5 GHz. It can be seen that the complex magnetic permeability (imaginary part) μ″ shows a peak near f=2.5 GHz. From FIG. 3C, although the complex magnetic permeability (imaginary part) μ″ as the synthesis result shows slightly weak peaks near f = 2.5 GHz and 7.5 GHz, compared to Reference Examples 1 and 2, f = It can be seen that the rate of change in the frequency band from 2.5 GHz to 7.5 GHz is small.

FIG. 4A shows the measurement results of the frequency dependence of the complex permeability of the ferromagnetic laminated film of Example 1, where the real part μ′ is indicated by “●” and the imaginary part μ″ is indicated by “Δ”. In FIG. 4A, the predicted calculation result of the frequency dependence of the complex permeability (real part) μ′ is indicated by a dashed line, and the predicted calculation result of the frequency dependence of the complex permeability (imaginary part) μ″ is indicated by the double-dashed line. is indicated.

It can be seen from FIG. 4A that the complex magnetic permeability (imaginary part) μ″ of the ferromagnetic laminated film of Example 1 has a peak near the frequency f=3.5 GHz. Complex magnetic permeability (imaginary part) μ″ has a peak near f=3.5 GHz rather than near f=2.5 GHz because the thickness t ₂₁₁ of the first ferromagnetic layer 211 and the thickness t ₂₁₂ of the first ferromagnetic layer 212 have their design values (50 nm). It is presumed that this is due to the thicker (approximately 60 nm). The weak peak of the complex magnetic permeability (imaginary part) μ″ near f=7.5 GHz is due to the first ferromagnetic layer 211, which is the first ferromagnetic layer formed on the surface of the substrate 10 with small surface roughness. is more regular than the nanostructure of the initial growth layers in the second ferromagnetic layers 221 and 222 formed on the surface of the insulating layer 30 having a large surface roughness. It is presumed that this is because the frequency dependence of the magnetic susceptibility became dominant. It is presumed that this is because the frequency dependence of the complex magnetic permeability of is small.

FIG. 4B shows the result of multiplying the complex magnetic permeability (imaginary part) μ″ by the angular frequency ω (2πf) and converting it into ω μ″, which has the same frequency characteristic shape as the AC resistance (real part of the impedance). It is shown. From FIG. 4B, it can be seen that the complex permeability (imaginary part) μ″ decreases in the frequency band f=3.5 to 7.5 GHz, while ω μ″ is made uniform.

FIG. 5 shows a cross-sectional TEM (transmission electron microscope) image of the ferromagnetic laminated film of the reference example. The ferromagnetic laminated film of the reference example has a five-layer structure in which five ferromagnetic layers 20 composed of nanogranular thin films having a thickness of 200 nm are laminated on a substrate 10 with insulating layers 30 interposed therebetween. The ferromagnetic layer 20 was deposited on the substrate 10 by the tandem method (see FIG. 2). The ferromagnetic layer 20 has a composition of (Co _0.84 Pd _0.16 ) ₈₂ -(Ca _0.33 F _0.67 ) ₁₈ as in the first embodiment. The insulating layer 30 had a composition represented by CaF ₂ and was designed to have a thickness of 10 nm.

In the range 200 where the first ferromagnetic layer 20 is 100 nm in the thickness direction from the interface with the substrate 10, the elongated nanoparticles are aligned in the thickness direction and have a columnar shape, whereas the range farther from the interface with the substrate 10 than that. , it can be seen that the nanoparticles are tilted obliquely. Single-phase _CaF2 usually has poor wettability, and when a single-layer film is formed on a glass substrate, the surface roughness is remarkably poor. improved, suggesting that it functions as an intermediate insulating layer. Incidentally, when the upper and lower films are exchange-coupled in the film via the intermediate layer, the magnetization becomes oblique magnetization or perpendicular magnetization, and the squareness deteriorates.

(Second embodiment)
(Constitution)
The ferromagnetic multilayer film as the second embodiment of the present invention shown in FIG. It has a four-layer structure in which the magnetic layer 222 and the two first ferromagnetic layers 211 and 212 are stacked in order with the insulating layer 30 interposed therebetween. Since the configuration other than this is the same as the ferromagnetic laminated film (see FIG. 1) as the first embodiment of the present invention, further explanation is omitted.

(Manufacturing method of ferromagnetic laminated film)
A method for manufacturing a ferromagnetic laminated film (see FIG. 6) as a second embodiment of the present invention comprises: a second ferromagnetic layer 221, an insulating layer 30, a second ferromagnetic layer 222, an insulating layer 30, a first ferromagnetic layer It includes fabricating layer 211 , insulating layer 30 and first ferromagnetic layer 212 in sequence on substrate 10 .

Since each of (1) the step of fabricating the ferromagnetic layer 20 and (2) the step of fabricating the insulating layer 30 is the same as in the first embodiment, further description is omitted.

(Evaluation of ferromagnetic laminated film)
(Example 2)
A ferromagnetic laminated film of Example 2 was fabricated according to the second embodiment. In Example 2, the ferromagnetic layer 20 has a composition represented by (Co _0.84 Pd _0.16 ) _0.82 −(Ca _0.33 F _0.67 ) _0.18 as in Example 1. FIG. The insulating layer 30 has a composition represented by _CaF2 . The thickness t212 of the thicknesses _t211 and 212 of the first ferromagnetic layers 211 is designed to be 50 nm, the thickness _t222 of the thicknesses _t221 and 222 of the second ferromagnetic layers ₂₂₁ is designed to be 500 nm, and the insulating layer The thickness of 30 was designed to be 10 nm.

In FIG. 7, the measurement results of the frequency dependence of the complex magnetic permeability of the ferromagnetic laminated film of Example 2 are shown with " ∘ " for the real part μ' and "Δ" for the imaginary part μ''. In FIG. 7, the predicted calculation result of the frequency dependence of the complex magnetic permeability (real part) μ′ is indicated by a dashed line, and the predicted calculation result of the frequency dependence of the complex magnetic permeability (imaginary part) μ″ is indicated by the double-dashed line. (see FIG. 3C).

From FIG. 7, it can be seen that the complex magnetic permeability (imaginary part) μ″ of the ferromagnetic laminated film of Example 2 is substantially constant from the vicinity of the frequency f=3.5 GHz to 7.5 GHz. The nanostructure of the initial growth layer in the second ferromagnetic layer 221, which is the first ferromagnetic layer formed on the surface of the small substrate 10, is the first ferromagnetic layer formed on the surface of the insulating layer 30 with large surface roughness. It is presumed that the frequency dependence of the complex permeability of the former becomes dominant because it is more regular than the nanostructure of the initial growth layers in 211 and 212. That is, the first ferromagnetic layer 211 and It is presumed that the nanostructure of the initial growth layer at 212 became irregular due to the magnitude of the surface roughness of the insulating layer 30, and the contribution rate of the frequency dependence of the complex magnetic permeability of 212 decreased. be.

(Other embodiments of the present invention)
In the above embodiment, the first ferromagnetic layer group (first ferromagnetic layers 211 and 212) and the second ferromagnetic layer group (second Although the ferromagnetic laminated film was constructed by laminating the ferromagnetic layers 221 and 222), as another embodiment, the thickness is included in each of three or more different (non-overlapping) thickness ranges. A ferromagnetic laminated film may be formed by laminating the first to n-th ferromagnetic layer groups (3≦n).

In the above embodiment, the number of ferromagnetic layers constituting each ferromagnetic layer group laminated via an insulating layer was "2". The number of layers may be "1" or "3 or more". In the above embodiment, the number of ferromagnetic layers constituting each ferromagnetic layer group laminated via an insulating layer is the same. may be different from the number of ferromagnetic layers constituting another ferromagnetic layer group.

One ferromagnetic layer group and A ferromagnetic laminated film may be configured by laminating a plurality of ferromagnetic layers including the other ferromagnetic layer group via an insulating layer.

(Example 3)
A ferromagnetic laminated film of Example 3 was fabricated according to the third embodiment of FIG. In Example 3, the ferromagnetic layer 20 has a composition represented by (Co _0.84 Pd _0.16 ) _0.82 −(Ca _0.33 F _0.67 ) _0.18 as in Example 1. The insulating layer 30 has a composition represented by _CaF2 . The thickness t212 of the thicknesses _t211 and 212 of the first ferromagnetic layers 211 is designed to be 50 nm, the thickness _t222 of the thicknesses _t221 and 222 of the second ferromagnetic layers ₂₂₁ is designed to be 500 nm, and the insulating layer The thickness of 30 was designed to be 10 nm.

In FIG. 11A, the measurement results of the frequency dependence of the complex permeability of the ferromagnetic laminated film of Example 3 are shown with " ∘ " for the real part μ' and "Δ" for the imaginary part μ''. In FIG. 11A, the predicted calculation result of the frequency dependence of the complex permeability (real part) μ′ is indicated by a dashed line, and the predicted calculation result of the frequency dependence of the complex permeability (imaginary part) μ″ is indicated by the double-dotted chain line. (see FIG. 3C).

From FIG. 11A, it can be seen that the complex magnetic permeability (imaginary part) μ″ of the ferromagnetic laminated film of Example 1 is maintained at a high value, although it is difficult to say that it is substantially constant from the vicinity of the frequency f=5.2 GHz to 10.9 GHz. This is because the nanostructure of the initial growth layer in the first ferromagnetic layer 211, which is the first ferromagnetic layer formed on the surface of the substrate 10 with small surface roughness, is formed on the surface of the insulating layer 30 with large surface roughness. is more regular than the nanostructure of the initial grown layers in the second ferromagnetic layers 211, 212 and the first ferromagnetic layer 212 formed in the first ferromagnetic layer 212, the frequency dependence of the complex permeability of the first ferromagnetic layer 211 is In addition, since the first ferromagnetic layers 211 and 212 do not form a laminated structure, the first ferromagnetic layer has two characteristics of a single layer of 60 nm. In addition, the second ferromagnetic layers 211 and 212 forming a laminated structure are also magnetically coupled to the respective first ferromagnetic layers.The complex magnetic permeability in FIG. Although the contribution of the nanostructure of the initial growth layer in the first ferromagnetic layer 211 alone in contact with the substrate 10 is high, the magnitude of magnetic permeability is smaller and the natural resonance frequency is higher than when the first ferromagnetic layer 212 and the laminated structure are formed. This, and somehow the complex permeability of the laminated structure consisting of the second ferromagnetic layers 211 and 212 with their pre-resonant frequencies raised by 211 and 222, and the deposition on the insulating layer 30, which contributes more than 211 It is presumed that the same effects as in Examples 1 and 2 are obtained, although the structure is complicated in that the complex magnetic permeability due to 212 having a low .DELTA. is superimposed.

FIG. 11B shows the result of multiplying the complex magnetic permeability (imaginary part) μ″ by the angular frequency ω (2πf) and converting it into ω μ″ which has the same frequency characteristic shape as the AC resistance (real part of the impedance). It is shown. From FIG. 11B, it can be seen that the complex permeability (imaginary part) μ″ decreases in the frequency band f=6.0 to 12.0 GHz, while ω μ″ is made uniform. Compared to FIG. 4AB, the frequency band where μ″ is high has a higher frequency, so it can be seen that ω·μ″ also maintains a high value in a higher frequency band.

The ferromagnetic laminated film of the present invention relates to a super-high frequency magnetic thin film having uniaxial magnetic anisotropy in the film plane, which is used for electromagnetic induction electronic devices of electronic equipment. In recent years, the speed of information processing and transmission in electronic devices has been rapidly increasing, and their operating frequencies have changed from the conventional high frequency band (1 GHz or less) to the 2.4 GHz band of the wireless LAN standard, for example. It has risen to microwaves (~3 GHz).

In the future, in order to increase the communication speed, the SHF band (from 3 GHz) will become mainstream, for example, the 5.2 GHz standard that conforms to the 5th generation mobile communication system, and the 28 GHz standard wireless LAN. be. In recent years, electronic devices have become multi-functional and miniaturized, so electronic devices occupying most of the internal volume, such as inductors, couplers, baluns, noise filters, and other electromagnetic inductive high-frequency magnetic devices, have been miniaturized and integrated. There is a strong demand for

For this purpose, it is very effective to introduce a magnetic material into a conventional air-core magnetic device to reduce the reluctance of the magnetic circuit, or to keep the magnetic field in the magnetic material and sometimes absorb it. In order to achieve the above, a magnetic material that maintains a constant magnetic permeability μ' up to at least 1 GHz or more, in other words, a material with an extremely high natural resonance frequency of 3 GHz or more due to the magnetic permeability μ" is desired, which also has the effect of noise suppression. Furthermore, as a recent trend of electronic devices, thin-film devices and integration with semiconductor ICs are being actively studied, and magnetic substances are expected as thin-film materials.

A technique that can change the high-frequency characteristics of a magnetic material to a range as if the composition were controlled only by controlling the film thickness of the laminated film contributes to cost reduction and has great industrial advantages.

10: substrate 20: ferromagnetic layer 211, 212: first ferromagnetic layer 221, 222: second ferromagnetic layer 30: insulating layer 41: first cathode 42: second cathode 44: anode .

Claims (7)

General formula L _1-ab M _a F _b (L: one or more elements selected from Fe, Co and Ni (excluding Ni alone), or one or more elements selected from Fe, Co and Ni and an alloy of one or more noble metal elements selected from Pd and Pt (the atomic ratio of the noble metal element in the alloy is 0.50 or less), M: Li, Mg, Al, Ca, one or more elements selected from Sr, Ba, Gd and Y; F: fluorine; ) and a plurality of ferromagnetic layers having a nanogranular structure in which magnetic particles represented by L and having an average particle size of 1 to 20 nm are uniformly distributed in an insulating matrix made of a fluoride of M;
an insulating layer having a composition represented by the general formula M _c F _d (1 ≤ c ≤ 2, 1 ≤ d ≤ 3);
having a structure in which the plurality of ferromagnetic layers including the first ferromagnetic layer formed on a substrate are laminated via the insulating layer;
The plurality of ferromagnetic layers include one or more first ferromagnetic layers having a thickness included in a first thickness range and a first ferromagnetic layer having a lower limit value larger than the upper limit value of the first thickness range. and one or more second ferromagnetic layers having a thickness within the thickness range of 2. In the ferromagnetic multilayer film according to claim 1,
The plurality of first ferromagnetic layers are laminated in order via the insulating layer, and alternatively or additionally, the plurality of second ferromagnetic layers are laminated in order via the insulating layer. ferromagnetic laminated film. In the ferromagnetic laminated film according to claim 1 or 2,
A ferromagnetic laminated film, wherein the first ferromagnetic layer is composed of the first ferromagnetic layer. In the ferromagnetic laminated film according to claim 1 or 2,
A ferromagnetic laminated film, wherein the first ferromagnetic layer is composed of the second ferromagnetic layer. In the ferromagnetic multilayer film according to any one of claims 1 to 4,
A ferromagnetic laminated film, wherein the first thickness range is in the range of 20-200 nm, and the second thickness range is in the range of 250-2000 nm. An electromagnetic induction electronic component comprising the ferromagnetic laminated film according to any one of claims 1 to 5. A method for manufacturing a ferromagnetic multilayer film according to claim 1,
a structure in which the plurality of ferromagnetic layers including the first ferromagnetic layer formed on a substrate are laminated via the insulating layer, and the plurality of ferromagnetic layers have a first thickness range; one or more first ferromagnetic layers having a thickness included in and one or more thicknesses included in a second thickness range having a lower limit value larger than the upper limit value of the first thickness range, or A method of manufacturing a ferromagnetic film stack comprising: a plurality of second ferromagnetic layers;
A step of fabricating the first ferromagnetic layer, a step of fabricating the second ferromagnetic layer, and a step of fabricating the insulating layer,
Each of the step of fabricating the first ferromagnetic layer and the step of fabricating the second ferromagnetic layer includes:
One or more ferromagnetic elements consisting of L which is one or more elements selected from Fe, Ni and Co (excluding single Ni) or one or more ferromagnetic elements selected from Fe, Co and Ni, Pd and a first cathode comprising one or more noble metal elements selected from Pt; and a fluoride of M being one or more elements selected from Li, Mg, Al, Ca, Sr, Ba, Gd and Y generating sputtered particles from each of the first cathode and the second cathode by independently controlling the power supplied to each of the second cathodes consisting of
rotating the anode to periodically pass the substrate supported by the anode to a position where sputtered particles emitted from each of the first cathode and the second cathode are incident;
The step of producing the insulating layer includes:
generating sputtered particles from the second cathode by controlling power supplied to the second cathode;
A method of manufacturing a ferromagnetic laminated film, comprising the step of arranging the substrate at a position where sputtered particles emitted from the second cathode are incident by controlling the rotation angle of the anode.

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