JP2020031084A - Ferromagnetic laminated film, manufacturing method of the ferromagnetic laminated film, and electromagnetic induction electronic component - Google Patents

Abstract

To provide a ferromagnetic thin film or the like capable of enhancing an effect such as a high magnetic permeability or the like, achieved by a ferromagnetic thin film having a nano granular structure.SOLUTION: A ferromagnetic laminated film includes a structure in which a plurality of ferromagnetic layers 11 and 12 and an insulation layer 21 are laminated so that the insulation layer 21 is nipped between the ferromagnetic layers 11 and 12 which are opposite. Each of the ferromagnetic layers 11 and 12 has a composition expressed by a general formula: LMF, and a nano granular structure in which a magnetic particle of 1 to 20 nm in a mean diameter, expressed by L is formed by M fluorine, and which is uniformly distributed in an insulation matrix. L is one or more kind elements selected from Fe, Co, and Ni (however, a single Ni is excluded). M is one or more kind elements selected from Li, Mg, Al, Ca, Sr, Ba, Gd, and Y. F if fluoride, and satisfies the following equations: 0.03≤a≤0.07, 0.06≤b≤0.18, and 0.10≤a+b≤0.24. The insulation layer includes the composition expressed by a general formula: MF(1≤c≤2, and 1≤d≤3).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ferromagnetic laminated film having a structure in which a ferromagnetic layer is laminated with an insulating layer interposed therebetween, wherein the characteristics can be controlled only by changing the thickness of one magnetic layer.

  As the fifth generation mobile communication uses the SHF band (3 to 30 GHz), there is a need in the industry for inductor materials and noise suppression materials suitable for the use. For example, it is said that the eddy current loss is dominant in the noise suppression effect at high frequencies of a large-area film, but the magnetic film having a magnetic permeability μ equal to or greater than the magnetic permeability of air has a skin of an electromagnetic wave of frequency f. The depth d is expressed by the relational expression (1) using the specific resistance ρ of the magnetic film. As is clear from the relational expression (1), the skin depth d decreases as the relative permeability μ increases.

d = (ρ / πfμ) ^1/2 ‥ (1).

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

^{_{P e = (πtfB) 2 /}} 6ρ ‥ (2).

The skin depth d and the eddy current loss P _e, is a trade-off with respect to the specific resistance [rho, if both the frequency f becomes higher, d is thin, P _e increases, the harsh conditions as a loss . Furthermore, if the thickness t is more than the skin depth d, the influence of the eddy current loss P _e becomes remarkable. In order to use the inductor for low loss, it is ideal that t is one third or less of d. 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, the noise suppression effect due to the eddy current loss of a magnetic film having a higher specific resistance ρ than that of a metal but having a high magnetic permeability μ is generally higher than that of a metal, and has frequency selectivity.

  Both the eddy current loss and the magnetic loss depend on the frequency characteristic of the complex magnetic permeability μ (= μ′−jμ ″). Here, there is uniaxial anisotropy in the film plane, and the high-frequency magnetic permeability in the hard magnetization direction is high. The calculation results are shown in Fig. 15A and Fig. 15B.According to the calculation results shown in Fig. 15A, the variance of the anisotropy is small, and the imaginary part (loss) of the complex permeability μ "(broken line) is reduced. It rises sharply around the maximum magnetic resonance frequency. According to the calculation result shown in FIG. 15B, the dispersion of the anisotropy is large, and the imaginary part μ ″ of the complex magnetic permeability changes gently around the magnetic resonance frequency at which it becomes the maximum. The electromagnetic induction components such as inductors using the real part μ '(solid line) and filters for absorbing noise at a specific frequency all have a sharp rise in the imaginary part μ ”of magnetic permeability, and loss in frequency bands outside the target range. Should not be high.

For noise suppression materials, the effect is that the magnetic permeability μ is not excessively high, the specific resistance ρ is not excessively low or low, and the magnetic resonance frequency is high, so that the magnetic flux does not propagate too far through the magnetic material. Occurs in a high frequency band (for example, see 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 magnetic susceptibility as in the relational expression (3). You. S is the cross-sectional area of the magnetic path of the device, N is 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

FIG. 2 shows a cross-sectional STEM (scanning transmission type) 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 the substrate S by a tandem method (described later). An electron microscope) observation image is shown. The nanostructure of the initial layer near the interface with the substrate S (the layer whose distance from the substrate is within, for example, 100 nm) (see an enlarged image (lower right section in frame R1 in FIG. 2) in FIG. This is different from the nanostructure of the main layer separated from S (see an enlarged image (upper right section) in a frame R2 in FIG. 2).

  In a region where the magnetic particles (L) increase in the film composition and become ferromagnetic, the shape of the granule changes from a sphere to a spheroid. This longitudinal direction corresponds to a crystallographic easy magnetization direction. In the main layer, the longitudinal direction of the granules is inclined from the film thickness direction to the in-plane direction of the film, and the crystal orientation is observed (the direction in which the granules are inclined is deviated). In-plane uniaxial anisotropy is more likely to be obtained than in a ferromagnetic film having a nano-granular structure (hereinafter, referred to as a “conventional film”). Is improved.

  In the initial layer, the longitudinal direction of the granules is oriented in the film thickness direction and is similar to the structure of the conventional film. Therefore, like the conventional film, (1) good soft magnetism (coercive force tends to be low). (2) It is considered to have a characteristic that the anisotropic magnetic field is low and it is hard to be applied unless the film is formed in a magnetic field.

  Therefore, if the film thickness is reduced, the influence of the initial layer becomes large, and the nanogranular thin film has a high specific resistance in the first place. Therefore, (1) high permeability (not recovery of eddy current loss), (2) low frequency (not recovery of eddy current loss), (3) low coercive force (same as metal magnetic film) Effects) and (4) Reduction of anisotropic dispersion (the same effects as the metal magnetic film) are considered to provide some effects different from those of a homogeneous metal magnetic thin film.

  Therefore, it is an object of the present invention to provide a ferromagnetic thin film or the like that can enhance the effect of increasing the magnetic permeability and the like provided by a ferromagnetic thin film having a nanogranular structure.

The ferromagnetic laminated film of the present invention has a structure in which a plurality of the ferromagnetic layers and at least one of the insulating layers are laminated such that an insulating layer is sandwiched between a pair of ferromagnetic layers. Wherein the ferromagnetic layer is composed of a general formula L _{1 -abM a} F _b (L: one or more elements selected from Fe, Co and Ni (excluding Ni alone), or Fe, Alloy of one or more ferromagnetic elements selected from Co and Ni and 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: 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, having a composition represented by 0.10 ≦ a + b ≦ 0.24) And has a nano granular structure in which magnetic particles having an average particle diameter 1~20nm are uniformly distributed in the insulating matrix comprising a fluoride of M represented by L, the insulating layer has the general formula M _c F _d (1 ≦ c ≦ 2, 1 ≦ d ≦ 3).

  The method for manufacturing a ferromagnetic laminated film according to the present invention includes a step of forming the ferromagnetic layer and a step of forming the insulating layer. One or more ferromagnetic elements selected from L, which is one or more selected elements (excluding Ni alone), or one or more ferromagnetic elements selected from Fe, Co and Ni, and one selected from Pd and Pt And a second cathode comprising a fluoride of M, which is at least one element selected from Li, Mg, Al, Ca, Sr, Ba, Gd and Y. The step of generating sputtered particles from each of the first cathode and the second cathode by independently controlling the power supply to each of them, and the step of supporting the anode by rotating the anode Periodically passing the substrate to a position where sputtered particles emitted from each of the first cathode and the second cathode are incident, wherein the step of forming the insulating layer comprises: Generating a sputter particle from the second cathode by controlling the power supplied to the substrate; and controlling the rotation angle of the anode to allow the substrate to enter the position where the sputter particle emitted from the second cathode is incident. And a step of arranging them at the same position.

  According to the ferromagnetic laminated film of the present invention, the thickness of the ferromagnetic layer having a nanogranular structure is adjusted so that the influence of the initial layer (the layer in which the longitudinal direction of the granules is oriented in the film thickness direction) becomes large. Therefore, (1) high magnetic permeability (not recovery from eddy current loss deterioration), (2) low frequency (not recovery from eddy current loss deterioration), (3) low coercive force (with metal magnetic film) It is considered that some effects different from a homogeneous metal magnetic thin film, such as (4) reduction of anisotropic dispersion (the same effect as a metal magnetic film), can be obtained.

FIG. 1 is a configuration explanatory view of a ferromagnetic laminated film as one embodiment of the present invention. FIG. 3 is an explanatory diagram relating to a nanostructure of a ferromagnetic layer included in the ferromagnetic laminated film. FIG. 4 is an explanatory diagram relating to a method for manufacturing a ferromagnetic laminated film as one embodiment of the present invention. FIG. 4 is an explanatory diagram relating to an in-plane static magnetization curve (only the direction of easy magnetization) of the ferromagnetic laminated film. FIG. 5A is an explanatory diagram relating to a transmission electron microscope observation result showing that a multilayer film is formed at a target film thickness. FIG. 5B is an explanatory diagram relating to the result of measuring the thickness of the intermediate insulating layer in FIG. 5A. Illustration of frequency dependence of complex magnetic permeability (imaginary part) of ferromagnetic laminated film FIG. 4 is an explanatory diagram relating to a film thickness dependency of an apparent Gilbert damping coefficient of a ferromagnetic laminated film. FIG. 4 is an explanatory diagram relating to the film thickness dependence of the anisotropic magnetic field of the ferromagnetic laminated film. FIG. 4 is an explanatory diagram relating to the film thickness dependence of the coercive force of the ferromagnetic laminated film. FIG. 10A is an explanatory diagram regarding a transmission electron microscope result in which the structure in FIG. 2 is obtained even in a laminated film. FIG. 10B is an enlarged view of an evaluation point in FIG. 10A. FIG. 4 is an explanatory diagram relating to conduction noise suppression (P _loss / P _in ) of the ferromagnetic laminated film. FIG. 4 is an explanatory diagram relating to near-end crosstalk (S ₃₁ ) of a ferromagnetic laminated film. Explanatory drawing about the far end crosstalk ( _S41 ) of a ferromagnetic laminated film. FIG. 4 is an explanatory diagram regarding P _loss / P _in regarding a comparison between the magnetic laminated film of the present invention and a paramagnetic metal film. FIG. 15A shows a calculation result of a high-frequency magnetic permeability in a direction in which magnetization is difficult in a case where uniaxial anisotropy is present in the film plane (in the case where anisotropic dispersion is small). FIG. 15B shows a calculation result of a high-frequency magnetic permeability in a direction in which magnetization is difficult when there is uniaxial anisotropy in a film plane (when anisotropic dispersion is large).

(Structure of ferromagnetic laminated film)
In the ferromagnetic laminated film as one embodiment of the present invention shown in FIG. 1, a first ferromagnetic layer 11 and a second ferromagnetic layer 12 are laminated with an insulating layer 21 interposed therebetween. It has a three-layer structure. The n-th ferromagnetic layer (n ≧ 2) and the (n + 1) -th ferromagnetic layer are laminated so as to sandwich an insulating layer therebetween, thereby forming a ferromagnetic laminated film having a (2n + 1) -layer structure. You may.

The ferromagnetic layers 11 and 12 have 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, and Pd and An alloy with one or more noble metal elements selected from Pt (the atomic ratio of the noble metal element 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 layers 11 and 12, Ni has a low saturation magnetization, and therefore these metals alone are excluded from L. Therefore, as L, Co alone, Fe alone, Co-Fe, Co-Ni, Co-Ni-Fe or the like is used. When a is smaller than 0.03 and / or b is smaller than 0.06, the specific resistance ρ of the ferromagnetic layers 11 and 12 becomes excessively small (for example, 1.0 × 10 ² μΩ · cm or less). . When a is greater than 0.07 and / or b is greater than 0.18, both the saturation magnetization and the anisotropic magnetic field of the ferromagnetic layers 11 and 12 are reduced, and a single-layer film of about 1000 nm has a GHz band ( It becomes difficult to obtain a ferromagnetic resonance frequency of, for example, 7 GHz or more.

Specifically, in LMF, when the total atomic ratio (a + b) of M and F is 0.25 or more, the contact of the granules made of metal L decreases, and the specific resistance increases ( For example, it reaches 1 × 10 ³ μΩ · cm or more), but the magnetic coupling between the granules is reduced, and the long-range permeability of the magnetocrystalline anisotropy is reduced, so that the anisotropic magnetic field is also reduced. The magnetization is simply diluted by a decrease in the space occupancy of the magnetic material. Further, in a composition region in which the total atomic ratio of M and F exceeds 0.60, the distance between the granules made of the metal L becomes large, so that the magnetically coupled granules almost disappear, and the ferromagnetic property of the film is reduced. Is lost (superparamagnetism). "Ferromagnetic" does not include "superparamagnetism", meaning that the granular density of the nanogranular film has decreased and it is no longer ferromagnetic, and magnetic metal granules are densely packed as much as possible Need to be done.

Therefore, in the ferromagnetic layers 11 and 12, in the composition range where the total atomic ratio (a + b) of M and F is 0.24 or less, in other words, the atomic ratio of L (1- (a + b)) is 0.76 or more. In particular, the anisotropic magnetic field and the saturation magnetization increase. However, when the atomic ratio of L exceeds 0.90 or the total atomic ratio of M and F becomes 0.10, the magnetic properties of the ferromagnetic layers 11 and 12 are improved, but the specific resistance is significantly reduced ( For example, it is less than 1.0 × 10 ² μΩ · cm), and there is no difference from the conventional metal material in terms of eddy current loss. When the magnetization is small (for example, smaller than 3.5 kG), when only the anisotropic magnetic field is increased, the static magnetic permeability is lower than 3, and it is difficult to distinguish the air from the air in device application. When the magnetization is too large (for example, when it exceeds 21.5 kG), the specific resistance ρ of the ferromagnetic layers 11 and 12 becomes low (for example, below 1.0 × 10 ² μΩ · cm).

  The ferromagnetic layers 11 and 12 have a nano-granular structure in which magnetic particles (granules) having an average particle diameter of 1 to 20 nm represented by L are uniformly distributed in an insulating matrix made of M fluoride. It is required that the granules be close to or in contact with each other to cause exchange interactions. When the granules come into contact with each other, they are also magnetically coupled, but the relatively large proportion of the granules come into direct contact, so that the specific resistance is greatly reduced. Therefore, it is necessary that a current path that macroscopically passes through the nanogranular film is electrically separated to some extent by the insulator. When the distance between the granules is smaller than about 1 nm, both the magnetic interaction between the granules and the tunneling of electrons through the insulator due to quantum effects occur simultaneously. The specific resistance of a substance exhibiting electrical conduction by tunnel conduction is higher than that of metal conduction. However, since the insulating properties inherent to the insulator are significantly impaired, it is important to select a material having particularly excellent intrinsic insulating properties. The fluoride insulator achieves a high specific resistance in order to limit the current path even under conditions of tunnel conduction at a distance of about 1 nm or less that causes magnetic coupling or metal conduction by contact for the reason described below. be able to.

  In order for the granules to be magnetically coupled to each other, it is necessary to increase the total volume of the granules, in other words, the packing density of the granules, so that the amount of metal in the thin film increases. In this case, the ferromagnetism increases, and a high ferromagnetic resonance frequency can be achieved, but the specific resistance decreases because the amount of the insulator relatively decreases. In order to prevent the decrease in the specific resistance from being lower than that of the conventional metal-based material, it can be solved by using a fluoride insulator to be discussed below as a matrix material of granules.

  In a mechanism (random anisotropy) in which the nanostructured magnetic material causes an effective decrease in crystal magnetic anisotropy to generate soft magnetism (random anisotropy), anisotropic magnetic field decreases while exhibiting soft magnetism. However, a nanogranular material can have a certain crystal orientation unlike a general nanostructured soft magnetic material. That is, it is effective to use a magnetic metal having high crystal magnetic anisotropy for the granules.

Nano-granular structures containing fluoride crystals have high specific resistance. This is because fluorides such as MgF ₂ and CaF ₂ have a larger energy band gap 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 of which are values of a single crystal), which means that the specific resistance increases. A feature of the nano-granular structure film using a fluoride is that the fluoride forms a crystal structure, unlike the case where a nitride or an oxide is used. The fact that the material has a crystalline structure means that the composition is stable near the stoichiometric composition, and unlike a material having an amorphous structure, the band gap does not decrease. Since the mixing of the fluoride is suppressed, it is possible to achieve a higher electric resistance in a very high level as compared with the related art. In addition, if such an insulator is used, a conventional oxide or nitride is used as a matrix material even in a material having a metal amount in a region where the contact between granules increases and the specific resistance decreases. The specific resistance is relatively higher than that of a conventional nanogranular ferromagnetic film.

Co is a material having a high crystal magnetic anisotropy constant of the order of 10 ⁶ erg / cm ³ even when used alone. Fe and Ni also have a crystal anisotropy of the order of 10 ⁵ erg / cm ^3, though weaker than Co. However, it is a well-known fact that when Fe or Ni is dissolved in Co as a solid solution, the anisotropy does not simply weaken, but rather increases. It is also known that when Pt and Pd, which are noble metals, are solid-dissolved in the magnetic metal, an anisotropy of the order of 10 ⁷ erg / cm ³ , which is dramatically increased, can be obtained. As described above, by selecting a metal composition of a highly anisotropic granule, the anisotropic magnetic field of a nanogranular film having a crystal orientation can be increased.

  By making the magnetic metal granules an alloy containing a precious metal of Pd or Pt which is extremely chemically stable, the anti-fluorination property of the magnetic metal granules can be enhanced and the phase separation from the fluoride matrix can be promoted. . When the element L constituting the magnetic metal granule is combined with F, the saturation magnetization of the film is reduced, but Pd and Pt have the effect of minimizing this. Further, since Pd and Pt have the effect of significantly increasing the anisotropic magnetic field, Ni alone can be used. However, since Pd and Pt are non-magnetic metals, if their atomic ratio exceeds 50%, the anisotropy increases but the saturation magnetization decreases, and as a result, the anisotropic magnetic field also decreases. Is not preferable because high performance exceeding 7 GHz cannot be maintained and the magnetostriction constant also increases significantly.

Each of the thickness t ₁₁ of the first ferromagnetic layer ₁₁ and the thickness t ₁₂ of the first ferromagnetic layer 12 is designed to be in the range of 10 to 2000 nm, more preferably 10 to 1000 nm. I have. The thickness t ₁₁ of the first ferromagnetic layer ₁₁ and the thickness t ₁₂ of the first ferromagnetic layer 12 may be designed to be the same, or may be designed to be different. Since the thickness of the ferromagnetic layers 11 and 12 is designed to be substantially the same as that of the above-described initial layer, a portion having the same nanostructure as the initial layer (see an enlarged image in the frame R1 in FIG. 2 (lower right section)). (Larger than the nanostructure of the main layer (see the enlarged image in the frame R2 in FIG. 2 (upper right))).

The insulating layer 21 has a composition represented by a general formula M _c F _d (1 ≦ c ≦ 2, 1 ≦ d ≦ 3). The thickness t ₂₁ of the insulating layer 21 is designed to be within the scope of 2 to 50 nm. This is because the first ferromagnetic layer 11 and the second ferromagnetic layer 12 are not exchange-coupled in the thickness direction via the insulating layer 21 without the insulating layer 21 being broken. This is for joining at the end of the.

(Method of manufacturing ferromagnetic laminated film)
The method for manufacturing a ferromagnetic laminated film (see FIG. 1) as one embodiment of the present invention includes: (1) a step of forming a first ferromagnetic layer 11; (2) a step of forming an insulating layer 21; (3) a step of producing the second ferromagnetic layer 12.

  (1) The step of fabricating the first ferromagnetic layer 11 includes the following steps: (1-1) independently controlling power supplied to each of the first cathode 41 and the second cathode 42 disposed in the chamber 40; A step of generating sputtered particles from each of the first cathode 41 and the second cathode 42, and (1-2) rotating the anode 44 so that the substrate S supported by the anode 44 is separated from the first cathode 41 and the second cathode 42. And periodically passing the sputtered particles emitted from each of them to a position where they are incident.

  As the substrate S, for example, D263 (trade name of Shot) glass manufactured by Shot Corporation having a thickness of about 0.2 mm, Eagle XG (trade name of Corning Corporation) glass of about 0.3 mm thickness, and 0.5 mm thickness An Si wafer whose surface is thermally oxidized, quartz glass having a thickness of 0.5 mm, or similarly, MgO and sapphire having a thickness of about 0.5 mm are used.

  (3) The step of forming the second ferromagnetic layer 12 includes the same steps (3-1) and (3-2) as the steps (1-1) and (1-2), respectively. In.

  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 include one or more ferromagnetic elements selected from Fe, Co, and Ni, and one or more noble metal elements selected from Pd and Pt. The second cathode 42 is made of a fluoride of M, which is one or more elements selected from Li, Mg, Al, Ca, Sr, Ba, Gd and Y.

  (2) a step of forming an insulating layer includes: (2-1) a step of generating sputtered particles from the second cathode 42 by controlling power supplied to the second cathode 42; Controlling the rotation angle to arrange the substrate S at a position where the sputtered particles emitted from the second cathode 42 enter.

  In FIG. 3, the first cathode 41 and the second cathode 42 are held downward and the anode 44 is held upward, so that the cathodes 41 and 42 and the anode 44 are arranged to face each other. In addition, the cathodes 41 and 42 and the anode 44 may be arranged to face 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 to face each other by holding the first cathode 41 and the second cathode 42 in a horizontal direction and holding the anode 44 in a horizontal direction. The cathodes 41 and 42 and the anode 44 may be arranged non-facing.

  The material forming each of the first cathode 41 and the second cathode 42 is sputtered, and sputter particles that are partially free radicalized fly out of the cathodes 41 and 42. The sputtered particles having negative charges are electrically attracted to the anode 44, and the first ferromagnetic layer 11, the insulating layer 21, and the second ferromagnetic layer 12 are formed on the substrate S in this order. You.

  The power supplied to the first cathode 41 and the second cathode 42 is independent of each other by the first power supply 410 and the second power supply 420 so that the material of each cathode 41 and 42 corresponds to the composition of the layer. Controlled. Sputtered particles simultaneously sputtered from the first cathode 41 and the second cathode 42 reach the substrate S supported by the anode 44, and a layer having a desired composition is formed. A film having a desired composition is formed by periodically passing the substrate S near the first cathode and the second cathode. In order to control the incident angle of the sputtered particles, the cathodes 41 and 42 or the substrate S are provided with an arbitrary angle within a range where the magnetic anisotropy derived from the film structure is maintained, and the cathodes 41 and 42 and the anode 44 are opposed to each other. The arrangement relationship may be controlled. Similarly, in the case of the non-facing arrangement, a film having a desired composition is formed by periodically passing the position where the substrate S comes into contact with the sputtered particles.

  The anode 44 is driven to rotate at a constant or variable-speed rotation at a rotation speed included in a range of, for example, 1 to 200 rpm, and a peripheral speed (rotational force) corresponding to the rotation speed is applied to the surface of the substrate S to perform sputtering. Uniaxial orientation occurs in the ferromagnetic layers 11 and 12 even when no magnetic field is applied inside. In some cases, a magnetic field in the range of 100 to 500 Oe is applied to the substrate S in a direction in which anisotropy is given by the rotation of the anode 44, and the anisotropy of the ferromagnetic layers 11 and 12 is further enhanced.

  As a sputtering gas, for example, pure Ar gas is used. The pressure of the Ar gas forming the atmosphere of the substrate S is controlled within a pressure range of 1 to 20 mTorr. The sputter power by each of the first power supply device 410 and the second power supply device 420 is controlled to 10 to 1000 W. The thickness of the layer is adjusted according to the length of the film formation time. The substrate S is controlled by indirect water cooling or a predetermined temperature included in a temperature range of 100 to 800 ° C. Further, a pair of permanent magnets may be arranged on the substrate holder, and a static magnetic field of 100 to 500 Oe may be applied to the substrate S.

  The steps (1) to (3) or at least the steps (1) and (3) are performed in a static magnetic field or in a non-magnetic field. The substrate S may be heated by a heater (not shown) at a predetermined temperature included in a temperature range of 100 to 800 ° C. Each of the first ferromagnetic layer 11 and the second ferromagnetic layer 12 has a temperature of 100 to 800 ° C. in at least one of during and after fabrication, for example, in a static magnetic field and a rotating magnetic field, or in a non-magnetic field. The heat treatment is carried out by holding at a predetermined temperature included in the range, for example, a predetermined time included in a time range of 5 minutes to 5 hours. The in-plane uniaxial anisotropy is imparted to each of the ferromagnetic layers 11 and 12 by both the manufacturing process and the heat treatment process of each of the ferromagnetic layers 11 and 12. The anisotropic magnetic field in each of the ferromagnetic layers 11 and 12 can be controlled by a heat treatment in a static magnetic field of 300 Oe to 10 kOe or a rotating magnetic field. When the heat treatment temperature is lower than 100 ° C., there is almost no difference between the heat generation at the time of forming each layer and there is no effect. The upper limit of the heat treatment temperature of 800 ° C. is based on the heat resistance of the substrate and the device. is there.

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

(Evaluation of ferromagnetic laminated film)
FIG. 4 shows an in-plane static magnetization curve in the easy magnetization direction of the ferromagnetic multilayer film of the first embodiment. In the first embodiment, each of the first ferromagnetic layer 11 and the second ferromagnetic layer 12 has a composition represented by (Co _0.84 Pd _0.16 ) _0.82 − (Ca _0.33 F _0.67 ) _0.18 . The intermediate layer 21 has a composition represented by CaF ₂ . Each of the thicknesses t ₁₁ and t ₁₂ of the first ferromagnetic layer 11 and the second ferromagnetic layer ₁₂ is 500 nm, and the thickness t ₂₁ of the intermediate layer ₂₁ is 10 nm.

  From FIG. 4, it can be seen that the magnetization curve in the region where the magnetization is positive and the magnetization curve in the region where the magnetization is negative are shifted left and right with a step from the x axis. This is seen when the magnetic films having different upper and lower characteristics are not exchange-coupled in the film thickness direction via the intermediate layer in the film but are bonded at the film edge, and thus, the film is manufactured. It was confirmed that the ferromagnetic laminated film had a laminated structure (see FIG. 1).

  In addition to confirming the laminated structure from the magnetization curve, the cross section of the laminated film formed so that the ferromagnetic layer 11 becomes 200 nm, the intermediate layer 21 becomes 10 nm, and the ferromagnetic layer 11 becomes five using transmission electron microscope. The observed results are shown in FIGS. 5A and 5B. FIG. 5A shows that there are five 200 nm ferromagnetic layers 11. From FIG. 5B, it can also be confirmed that the thickness of the intermediate layer 21 is 10 nm and the film is not broken in the middle.

The CaF ₂ single phase usually has poor wettability, and when a single-layer film is formed on a glass substrate, the surface roughness is extremely poor. However, since the CaF ₂ single phase is sequentially formed on the nanogranular layer containing fluoride, the wettability is low. 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, oblique magnetization or perpendicular magnetization occurs, and the squareness deteriorates.
FIG. 6A shows the ferromagnetic multilayer films of Examples 1 to 4 having the configuration shown in Table 1 and the ferromagnetic single-layer films (ferromagnetic layers) of Comparative Examples 5 to 6 among Comparative Examples 1 to 6. Is one, and the film thickness dependence of the complex magnetic permeability spectrum (only the imaginary part) of the film having no intermediate layer) is shown. Complex permeability spectra in short-circuit end of the shorted shielded microstrip line, and insert the sample cut into 2 × 5 mm, measured S-parameters S _11, the commercial method of deriving permeability from here (shorted Microstrip line method).

  FIG. 6B shows the ferromagnetic laminated films of the ferromagnetic laminated films of Examples 5 to 8 having the configuration shown in Table 2 and the ferromagnetic single-layer films of Comparative Examples 11 to 12 among Comparative Examples 7 to 12. The thickness dependence of the complex permeability spectrum (only the imaginary part) of the film is shown. Comparative Example 13 is a single-layer film of Cu.

  6A and 6B, especially when the thickness of one ferromagnetic layer is about 100 nm or less, the imaginary part μ ″ of the complex magnetic permeability in the GHz band of the ferromagnetic laminated film is different from that of the ferromagnetic single-layer film. 100 nm is about the same as the thickness of the above-mentioned initial layer (see FIG. 2), and high permeability and low frequency can be achieved by a nanostructure similar to the conventional film. 6B, it was suggested that these effects were enhanced by the lamination.From FIG.6B, the resonance peak of the ferromagnetic laminated film of Example 5 was superimposed around 500 MHz together with the main peak around 5 GHz. In view of the Ms (0.8 T) of the film, Hk is a component having almost no anisotropy of about 0.1 kA / m, and it is difficult for the initial layer to have anisotropy. In a magnetic field It is considered that have influenced that not film.

  FIG. 7A shows the measurement results of the Gilbert damping coefficients α of the ferromagnetic multilayer films of Examples 1 to 4 and the ferromagnetic single-layer films of Comparative Examples 1 to 6. FIG. 7B shows the measurement results of the Gilbert damping coefficients α of the ferromagnetic multilayer films of Examples 5 to 8 and the ferromagnetic single-layer films of Comparative Examples 7 to 12. The apparent Gilbert damping coefficient α was determined by performing a fitting calculation based on the LLG equation for the imaginary part of the complex magnetic permeability.

Figure 8A is a measurement result of each of the anisotropic magnetic field H _k of the ferromagnetic single-layer film of the ferromagnetic multilayer films and Comparative Examples 1-5 Examples 1-4 are shown. FIG. 8B shows the measurement results of the anisotropic magnetic fields Hk of the ferromagnetic multilayer films of Examples 5 to 8 and the ferromagnetic single-layer films of Comparative Examples 6 to 10. The anisotropic magnetic field H _k was also obtained by performing fitting calculation based on the LLG equation for the imaginary part of the complex magnetic permeability.

In each of FIGS. 7A, 7B, 8A and 8B, the horizontal axis represents the thickness of one ferromagnetic layer for the ferromagnetic laminated film of the example, and the thickness of the ferromagnetic single-layer film of the comparative example. It represents the thickness. When the thickness is 200 nm or less, the measurement results of the ferromagnetic multilayer film (Examples 1 to 3 and 5 to 7) and the ferromagnetic single-layer film (see Comparative Examples 1 to 3 and 7 to 9) are different. cage, in particular, it can be seen that the Gilbert damping factor α and the anisotropic magnetic field H _k of the apparent ferromagnetic multilayer thin film in the range of 100nm is significantly lower.

  FIG. 9A shows the measurement results of the coercive force of the ferromagnetic multilayer films of Examples 1 to 4 and the ferromagnetic single-layer films of Comparative Examples 1 to 5. FIG. 9B shows the measurement results of the coercive force of the ferromagnetic multilayer films of Examples 5 to 8 and the ferromagnetic single-layer films of Comparative Examples 6 to 10. The coercive force was obtained from a static magnetization curve in the in-plane easy magnetization direction.

The CoPd alloy is more suitable as a semi-hard magnetic material than a soft magnetic material, and has a large coercive force in the first place instead of a strong anisotropy. From FIG. 9A, as for the ferromagnetic single layer film ((Co _0.84 Pd _0.16 ) ₈₂ − (Ca _0.33 F _0.67 ) ₁₈ film), when the film thickness is large, the coercive force is about 15 kA / m, and there is not much change. It can be seen that the coercive force increases (see Comparative Examples 1 to 3) while the coercive force decreases in the ferromagnetic laminated film (see Examples 1 to 3). From FIG. 9B, it can be seen that the ferromagnetic single-layer film ((Co _0.72 Pd _0.28 ) ₈₂ − (Ca _0.33 F _0.67 ) ₁₈ film) has little change in coercive force with respect to the film thickness, while the ferromagnetic thin film has Even if the thickness of one layer is 500 nm, the coercive force is reduced.
As described above, it was found that when the nanogranular films produced by the tandem method were laminated, a result different from that of the ordinary lamination of the metal single-phase film was obtained.

  FIGS. 10A and 10B show the results of confirming the initial layer of 100 nm suggested by the above magnetic characteristics with a transmission electron microscope. As in FIGS. 5A and 5B, the sample is a sample in which five 200-nm magnetic layers are stacked via an intermediate insulating layer (Example 3).

  In the range where one magnetic layer has a thickness of 100 nm from the substrate interface in the thickness direction, long and narrow nanoparticles are aligned in the thickness direction and are columnar, whereas in the direction further away from the substrate interface, the nanoparticles are inclined obliquely. You can see that it is. This is a result in which consistency with the assumption of FIG. 1 and the thickness dependence of the magnetic characteristics is obtained. Interpretation of transmission electron microscopy images not only on the surface but also on the inside of the nanoparticle has an interference effect and requires careful interpretation.However, even from experts, there is no doubt that this nanostructure difference Has got the opinion.

(Noise suppression effect of ferromagnetic laminated film)
Each of the ferromagnetic laminated film of each example and the ferromagnetic single-layer film of each comparative example has a line length of 10 mm, a characteristic impedance of 50Ω, and a two-line parallel type micro line having a line and space of 95 μm and 50 μm, respectively. After being placed on the strip line without weight, using a 4-port network analyzer, S ₁₁ (reflection of the main line), S ₂₁ (transmission of the main line), S ₃₁ (near the main line and the sub line) End crosstalk) and S ₄₁ (far end crosstalk between the main line and the sub line) were measured. The dimensions of the sample are 8 mm square.

11A to 13A respectively show the conduction noise suppression P _loss / P _in (= 1− (| S) of the ferromagnetic multilayer films of Examples 1 to 4 and the ferromagnetic single-layer films of Comparative Examples 5 to 6. ^{_{11 | 2 + | S 21 |}} 2)), are shown measurement results of the near-end crosstalk S ₃₁ and far-end crosstalk S _41, it is. 11B to 13B show the measurement results of P _loss / P _in , S ₃₁ , and S ₄₁ of the ferromagnetic multilayer films of Examples 5 to 8 and the ferromagnetic single-layer films of Comparative Examples 11 to 12, respectively. It is shown. In each of the examples and comparative examples, in the MHz band, there is no significant difference from the sample unloaded (Without Sample) and the substrate alone, but in the GHz band, P _loss / P _in increases, and the signal is large in S ₃₁ and S _41. It is declining. In particular, the ferromagnetic laminated films of Examples 1 to 2 and 5 to 6 (having a small thickness of the magnetic layer per layer) having large magnetic permeability and low resonance frequency and the thick single-layer films of Comparative Examples 6 and 12 are slightly lower. The effect is large from the frequency, and the inflection point corresponding to the magnetic resonance is also remarkably seen. As for the comparison between the easy magnetization direction and the hard magnetization direction, the hard magnetization direction changed at a higher frequency. Also, when a strong magnet was brought closer to change the magnetization state of the magnetic film, the dip position changed. Therefore, it can be seen that frequency selectivity is obtained according to the characteristics of the magnetic film. However, the difference due to the film composition was not as large as the change in the magnetic resonance frequency. This is because the eddy current loss is dominant as described above because the sample is as large as 8 mm square.

The fact that eddy current loss is dominant is important in comparison with a paramagnetic metal film. FIG. 14 shows the data of Example 1, Comparative Example 13, and no sample loaded with P _loss / P _in superimposed. The Cu film of Comparative Example 13 is significantly different from the others, and is approximately 1 in the MHz band and drops to 0.6 in the GHz band. This also implies, looks like a weak frequency selective, looking at the frequency characteristic of the S ₁₁ that determines the P _loss / P _in, since the power in Comparative Example 13 is reflected without being transmitted, P _loss / P _in was only visible large. Also, the S ₄₁ was found to capacitance of the transmission line is very large. The power is reflected because the capacitance is increased and the characteristic impedance is reduced to 10 to 20Ω over the entire measurement frequency range. The occurrence of electrical resonance at about 8 GHz is also evidence of an increase in capacitance. Thus, when Cu is loaded, it cannot be said that it has a frequency selectivity because it does not work as a high-frequency transmission line in the entire region. On the other hand, in the magnetic film, power absorption occurs only in the GHz band at the low frequency in the MHz band, as in the case of no sample loading. Therefore, it is effective to use a magnetic film for the fifth generation mobile communication, and it is effective to control the high frequency magnetic characteristics by the thickness of the magnetic layer.

  The ferromagnetic laminated film of the present invention relates to an ultrahigh-frequency magnetic thin film having uniaxial magnetic anisotropy in a film plane, which is used for an electromagnetic inductive electronic device of electronic equipment. 2. Description of the Related Art In recent years, the speed of information processing and transmission in electronic devices has been rapidly increasing, and their operating frequency has been changed from a conventional high-frequency band (1 GHz or less) to, for example, a 2.4 GHz band of a wireless LAN standard. It is increasing to microwaves (〜3 GHz).

  In the future, in order to increase the communication speed, for example, a wireless LAN based on the 5.2 GHz standard in the higher SHF band (3 GHz or higher) will be the mainstream. In addition, since electronic devices have been multifunctional and miniaturized in recent years, the miniaturization and integration of electronic devices that occupy a large part of the internal volume, for example, electromagnetically inductive high-frequency magnetic devices such as inductors, couplers, baluns, and noise filters There is a strong demand for conversion.

  For this purpose, it is very effective to introduce a magnetic material into a conventional air-core magnetic device to reduce the reluctance of a magnetic circuit, or to retain and sometimes absorb a magnetic field in a magnetic material. For the above reasons, a magnetic material that maintains a constant magnetic permeability μ ′ at least up to 1 GHz or more, in other words, a material whose magnetic resonance frequency due to magnetic permeability μ ″ is as high as 3 GHz or more is desired, which also has the effect of suppressing noise. In addition, as a recent trend of electronic devices, studies on thin film devices and integration with semiconductor ICs are being actively conducted, and magnetic materials are expected to be used as thin film materials.

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

11 {first ferromagnetic layer, 12} second ferromagnetic layer, 21} insulating layer, 41 {first cathode, 42} second cathode, 44} anode, S substrate.

Claims (5)

A ferromagnetic laminated film having a structure in which a plurality of the ferromagnetic layers and at least one of the insulating layers are stacked such that an insulating layer is sandwiched between a pair of ferromagnetic layers,
The ferromagnetic layer is composed of a general formula L _{1 -abM a} F _b (L: one or more elements selected from Fe, Co and Ni (excluding Ni alone), or Fe, Co and Ni) Alloys of one or more selected ferromagnetic elements 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: Li, One or more elements selected from 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 has a nanogranular structure in which magnetic particles having an average particle diameter of 1 to 20 nm represented by L are uniformly distributed in an insulating matrix made of M fluoride. ,
The insulating layer has the general formula _{M c F d (1 ≦ c} ≦ 2,1 ≦ d ≦ 3) ferromagnetic multilayer film, which has a composition represented by.   2. The ferromagnetic laminated film according to claim 1, wherein the thickness of each of the plurality of ferromagnetic layers is in the range of 10 to 2000 nm.   3. The ferromagnetic multilayer film according to claim 2, wherein the thickness of each of the plurality of ferromagnetic layers is in the range of 10 to 1000 nm.   An electromagnetic inductive electronic component comprising the ferromagnetic multilayer film according to claim 1. A method for manufacturing a ferromagnetic laminated film having a structure in which a plurality of the ferromagnetic layers and at least one of the insulating layers are laminated such that an insulating layer is sandwiched between a pair of ferromagnetic layers,
A step of forming the ferromagnetic layer, and a step of forming the insulating layer,
The step of producing the ferromagnetic layer,
One or more elements selected from Fe, Ni and Co (excluding Ni alone), or one or more ferromagnetic elements selected from Fe, Co and Ni, and Pd and A first cathode containing at least one noble metal element selected from Pt, and a fluoride of M that is at least one element 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 comprising:
Rotating the anode to periodically pass a 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 forming the insulating layer,
Controlling the power supply to the second cathode to generate sputter particles from the second cathode;
Controlling the rotation angle of the anode to dispose the substrate at a position where the sputtered particles emitted from the second cathode are incident.