JP2010010641A - Magnetic sheet and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic sheet used for an RFID or for suppressing an electromagnetic wave, the magnetic sheet being configured by sputtering a high-resistance soft magnetic film (Fe-M-O) on a substrate, and to provide a method of manufacturing the same. <P>SOLUTION: A magnetic sheet 4 is interposed in between an RFID tag 2 and a metallic member 3. The magnetic sheet 4 includes A-M-O elements in a resin sheet. The element A represents Fe or Co or their mixture; and the element M is at least either one of Hf, Ti, Zr, V, Nb, Ta, Mo, W, Al, Mg, Zn and Ca. Further, the magnetic sheet 4 is composed by sputtering the high-resistance soft magnetic film constituted by the membrane structure of an amorphous phase containing the compound of the elements M and O, and a fine-crystal phase with an average particle crystal size of ≤30 nm, mainly formed of one or two elements selected from Fe or Co dotted in the amorphous phase. This improves effectively the RFID characteristic and contributes to a thin-film structure. A thermal process is not required for the Fe-M-O film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic sheet used for an RFID device or an electromagnetic wave suppressor and a method for manufacturing the same.

  The demand for RFID (Radio Frequency ID) tags is increasing due to the spread of non-contact IC cards and their mounting on mobile phones and the like.

  The RFID tag includes an IC chip for recording information and a metal antenna, and enables wireless communication with a reader / writer.

However, when there is a metal in the vicinity of the RFID tag, there is a problem that an eddy current is generated in the metal due to the magnetic field from the reader / writer and the demagnetizing field due to the eddy current cancels the magnetic field necessary for wireless communication. .
JP-A-4-48707 JP-A-6-316748 JP-A-4-144210 Japanese Patent Laid-Open No. 11-186035 JP 2004-221522 A JP 2004-259787 A Journal of the Japan Institute of Metals 57, 1301 (1993) Journal of the Japan Society of Applied Magnetics 18, 750 (1994)

  Therefore, in order to solve the above problem, when a magnetic sheet is inserted between the metal and the RFID tag, the magnetic sheet attracts the magnetic flux from the reader / writer to the RFID tag side, and the antenna of the reader / writer and the RFID Magnetic flux can be passed between the antennas of the tag, the attenuation of the signal output received by the antenna of the RFID tag can be reduced, and the RFID characteristics can be improved.

  Conventionally, however, a high resistance soft magnetic film satisfying the real part μ ′ of complex relative permeability necessary for an RFID magnetic sheet and the specific resistance ρ is formed on the sheet by physical vapor deposition (for example, metal vapor deposition, sputter deposition). There was no RFID magnetic sheet formed by film or ion beam deposition.

  None of the above-mentioned patent documents 1 to 6 is used as a magnetic sheet for RFID, and naturally there is no recognition of the conventional problems of RFID described above, and no adjustment is made to the magnetic sputtered film in order to solve the conventional problems. .

  Also, for example, as disclosed in Patent Document 3, it is usually impossible to obtain good soft magnetic characteristics unless the magnetic film is subjected to heat treatment (annealing), and therefore the real part μ ′ of the complex relative permeability cannot be increased. Therefore, heat treatment is required to obtain good soft magnetic properties, but the material of the resin sheet is limited, or there is a problem that the dimensional accuracy decreases due to thermal deformation when the resin sheet is exposed to heat. It was.

  Further, in the past, it has been difficult to sufficiently increase the real part μ ′ of the complex relative permeability. Therefore, in order to effectively improve the RFID characteristics by inserting the RFID magnetic sheet, the magnetic film It was necessary to increase the film thickness. Or, conventionally, a bulk ferrite material is used, or a soft magnetic powder (for example, Sendust (registered trademark), which is an Fe-Al-Si alloy) mixed with a resin to form a sheet is used for RFID. Even if the real part μ ′ having such a large complex relative permeability could not be obtained, it could be used as a magnetic sheet for RFID. Conventionally, the resin sheet containing magnetic powder has a film thickness of at least 100 μm because it requires a large volume because the concentration of the magnetic material cannot be increased. However, inserting such a thick magnetic sheet between the RFID tag and the metal hinders the thickness reduction of the RFID device.

  The magnetic sheet can also be used as an electromagnetic wave suppressor built in as a noise countermeasure for a mobile phone or a personal computer.

  In order to improve the electromagnetic wave suppression characteristics (noise suppression effect), it is necessary to increase the imaginary part μ ″ of the complex relative permeability of the electromagnetic wave suppressor in a high frequency band of 100 MHz or higher, and the specific resistance ρ is also large. There must be.

  However, conventionally, there has been no electromagnetic wave suppressor formed by sputtering a high-resistance soft magnetic film having a large complex relative permeability imaginary part μ ″ and a large specific resistance ρ on a sheet.

  Therefore, the present invention is to solve the above-described conventional problems, and in particular, for magnetism for RFID or electromagnetic wave suppression obtained by sputtering a high-resistance soft magnetic film (Fe-MO) on a substrate. It aims at providing a sheet | seat and its manufacturing method.

  The magnetic sheet in the present invention is formed on a substrate with AMO (where the element A represents Fe or Co or a mixture thereof, and the element M is Hf, Ti, Zr, V, Nb, Ta, Mo, W, An amorphous phase containing a compound of the elements M and O, and one or two selected from Fe or Co interspersed in the amorphous phase. A magnetic film formed of a film structure with a main crystal grain size of 30 nm or less as a main crystal grain is formed by a physical vapor deposition method.

  As described above, in the present invention, a magnetic sheet having excellent soft magnetic properties can be obtained for RFID and electromagnetic wave suppression.

  In the present invention, the substrate is a flexible resin sheet including a resin casing of a portable device such as a mobile phone or a notebook PC, and the film structure of the magnetic film can be formed without heat treatment. Thereby, the resin sheet is not exposed to heat, a magnetic member having excellent dimensional accuracy can be formed, and the selectivity of the material of the resin sheet can be expanded.

In the present invention, the magnetic film has the element A of Fe, the composition formula is Fe _a M _b O _c , the composition ratio c of the element O is in the range of 6.85 to 47 at%, It is preferable that the composition ratio is in the range of 7.95 to 21.38 at%, the balance is the composition ratio a of the element Fe, and the relationship of a + b + c = 100 at% is satisfied. It can be formed in a mixed phase structure in which microcrystalline phases mainly composed of Fe are scattered in the amorphous phase.

  In the present invention, the element M is Hf, the composition ratio c of the element O is in the range of 6.85 to 47 at%, the composition ratio b of the element Hf is in the range of 11.40 to 15.74 at%, and the balance is It is preferable that the composition ratio a of the element Fe satisfies the relationship of a + b + c = 100 at%.

  Alternatively, in the present invention, the element M is Al, the composition ratio c of the element O is in the range of 699 to 16.75 at%, and the composition ratio b of the element Al is in the range of 9.79 to 21.38 at%. The remainder is the composition ratio a of the element Fe, and preferably satisfies the relationship of a + b + c = 100 at%.

  Alternatively, in the present invention, the element M is Zr, the composition ratio c of the element O is in the range of 8.11 to 9.29 at%, and the composition ratio b of the element Zr is in the range of 7.95 to 8.36 at%. The remainder is the composition ratio a of the element Fe, and preferably satisfies the relationship of a + b + c = 100 at%.

  The magnetic sheet is used for RFID devices. At this time, the thickness of the magnetic film is preferably in the range of 0.5 to 15 μm. As described above, according to the present invention, the attenuation of the received signal from the antenna of the RFID device, which serves as an index of the RFID characteristics, can be effectively reduced even if the magnetic film is made thinner than 15 μm. If the thickness of the magnetic film is thinner than 0.5 μm, the amount of attenuation increases, so the thickness of the magnetic film is set in the range of 0.5 to 15 μm.

Moreover, the said magnetic sheet can also be used for an electromagnetic wave suppression body.
The method for producing a magnetic sheet in the present invention is as follows.
On the substrate, A-M-O (where element A represents Fe or Co or a mixture thereof, and element M is Hf, Ti, Zr, V, Nb, Ta, Mo, W, Al, Mg, Zn, Ca) , Ce, and Y) are formed by physical vapor deposition, the gas pressure of the mixed gas of inert gas and O ₂ gas is in the range of 0.5 mTorr to 6 mTorr. And an amorphous phase containing a compound of elements M and O, and a microcrystalline phase having an average crystal grain size of 30 nm or less mainly composed of one or two kinds selected from Fe or Co interspersed in the amorphous phase A film structure is formed.

  As described above, by adjusting the gas pressure, a film structure of an amorphous phase and a microcrystalline phase can be formed, and good soft magnetic characteristics can be obtained.

In the present invention, in the magnetic film, the element A is Fe, the composition formula is Fe _a M _b O _c , the composition ratio c of the element O is in the range of 6.85 to 47 at%, and the composition of the element M It is preferable to form the magnetic film having a ratio in the range of 7.95 to 21.38 at%, the balance being the composition ratio a of the element Fe, and satisfying the relationship of a + b + c = 100 at%.

  In the present invention, the element M is Hf, the composition ratio c of the element O is in the range of 6.85 to 47 at%, the composition ratio b of the element Hf is in the range of 11.40 to 15.74 at%, and the balance Is the composition ratio a of the element Fe, and it is preferable to form the magnetic film satisfying the relationship of a + b + c = 100 at%.

  Alternatively, in the present invention, the element M is Al, the composition ratio c of the element O is in the range of 699 to 16.75 at%, and the composition ratio b of the element Al is in the range of 9.79 to 21.38 at%. Further, it is preferable to form the magnetic film satisfying the relationship of a + b + c = 100 at% with the balance being the composition ratio a of the element Fe.

  Alternatively, in the present invention, the element M is Zr, the composition ratio c of the element O is in the range of 8.11 to 9.29 at%, and the composition ratio b of the element Zr is in the range of 7.95 to 8.36 at%. Further, it is preferable to form the magnetic film satisfying the relationship of a + b + c = 100 at% with the balance being the composition ratio a of the element Fe.

  According to the present invention, a magnetic sheet having excellent soft magnetic properties for RFID or electromagnetic wave suppression can be obtained.

  Further, since the film structure of the magnetic film can be formed without heat treatment, the resin sheet supporting the magnetic film is not exposed to heat, and a magnetic member having excellent dimensional accuracy can be formed. The selectivity of can be expanded.

In addition, when a magnetic film is formed by physical vapor deposition, it is possible to form a film structure of an amorphous phase and a microcrystalline phase by optimizing the gas pressure of a mixed gas of an inert gas and O ₂ gas. Soft magnetic properties can be obtained.

  FIG. 1 is a schematic diagram of an RFID device and a reader / writer, FIG. 2 is a perspective view of a magnetic sheet according to an embodiment of the present invention, and FIG. 3 is a schematic diagram of a film structure of an Fe-MO film.

  As shown in FIG. 1, an RFID (Radio Frequency ID) device 1 includes an RFID tag 2 having an antenna and an IC chip, a metal member 3, and a magnetic sheet inserted between the RFID tag 2 and the metal member 3. 4.

  The RFID tag 2 has a form in which the antenna and the IC chip are formed on a substrate.

  The metal member 3 forms part of a housing, for example, and is made of Al, Ti, Cr, or the like. The metal member 3 has a film thickness T1 of about 0.05 to 0.5 mm.

  The magnetic sheet 4 inserted between the RFID tag 2 and the metal member 3 is obtained by sputtering a magnetic film 6 on a resin sheet 5 as shown in FIG.

  The magnetic film 6 is AMO (where the element A represents Fe or Co or a mixture thereof, and the element M is Hf, Ti, Zr, V, Nb, Ta, Mo, W, Al, Mg, Zn). , Ca, Ce, or Y).

  Here, in the magnetic film 6, the element A of the A-M-O film is Fe and is composed of a composition formula of FeaMbOc, and the composition ratio c of the element O is in the range of 6.85 to 47 at%. Is a high resistance soft magnetic film satisfying the relationship of a + b + c = 100 at% with the composition ratio b of 7.95 to 21.38 at% remaining, the balance being the element Fe composition ratio a.

  In this embodiment, the element M is Hf, the composition ratio c of the element O is in the range of 6.85 to 47 at%, the composition ratio b of the element Hf is in the range of 11.40 to 15.74 at%, The balance is the composition ratio a of the element Fe, and preferably satisfies the relationship of a + b + c = 100 at%. Thereby, the real part μ ′ of the complex relative permeability can be set to 50 or more and the specific resistance ρ can be set to 200 (μΩ · cm) or more. The composition ratio c of the element O is more preferably 27.08 to 47 at%, and the composition ratio b of the element Hf is more preferably 11.40 to 15.74 at%. Thereby, the real part μ ′ of the complex relative permeability can be set to 400 or more and the specific resistance ρ can be set to 300 (μΩ · cm) or more.

  Alternatively, in this embodiment, the element M is Al, the composition ratio c of the element O is in the range of 699 to 16.75 at%, and the composition ratio b of the element Al is in the range of 9.79 to 21.38 at%. Among them, the balance is the composition ratio a of the element Fe, and it is preferable that the relationship of a + b + c = 100 at% is satisfied. Thereby, the real part μ ′ of the complex relative permeability can be set to 50 or more and the specific resistance ρ can be set to 200 (μΩ · cm) or more. In the present embodiment, the composition ratio c of the element O is more preferably 12.20 to 16.75 at%, and the composition ratio b of Hf is preferably 12.68 to 15.17 at%. Thereby, the real part μ ′ of the complex relative permeability can be set to 300 or more and the specific resistance ρ can be set to 300 (μΩ · cm) or more.

  Alternatively, in the present embodiment, the element M is Zr, the composition ratio c of the element O is in the range of 8.11 to 9.29 at%, and the composition ratio b of the Zr is in the range of 7.95 to 8.36 at%. The remainder is the composition ratio a of the element Fe, and preferably satisfies the relationship of a + b + c = 100 at%. Thereby, the real part μ ′ of the complex relative permeability can be set to 100 or more and the specific resistance ρ can be set to 250 (μΩ · cm) or more. In the present embodiment, it is more preferable that the composition ratio c of the element O is 8.11 to 9.27 at%, and the composition ratio b of Hf is 7.95 to 8.36 at%. Thereby, the real part μ ′ of the complex relative permeability can be set to 800 or more and the specific resistance ρ can be set to 250 (μΩ · cm) or more.

  The magnetic film 6 may be formed directly on a resin casing such as a mobile phone or a notebook PC instead of the metal member 3.

Hereinafter, the magnetic film of the present invention is represented by the notation Fe-MO film 6.
As shown in FIG. 2, the Fe—M—O film 6 is partially sputtered on the entire surface of the resin sheet 5, for example, partially leaving the edge of the resin sheet 5, It may be formed only in the central portion of the resin sheet 5. However, when the magnetic sheet 4 and the RFID tag 2 are overlapped as shown in FIG. 1, the Fe-MO film 6 is formed to have a size that completely covers the entire surface of the RFID tag 2. Is preferred. Further, the resin sheet 5 may be a resin casing of a mobile device such as a mobile phone or a notebook PC.

  The Fe—M—O film 6 is formed without being subjected to heat treatment during the sputter deposition or after the sputter deposition. As shown in FIG. It is formed with a mixed phase structure of an amorphous phase 7 containing an O compound and a microcrystalline phase 8 mainly composed of Fe interspersed in the amorphous phase 7. The average grain size of the microcrystalline phase 8 can be 30 nm or less, and the crystal structure of the microcrystalline phase 8 can be a bcc structure. The microcrystalline phase 8 is not limited to the bcc structure, and may have an hcp structure or an fcc structure. The microcrystalline phase 8 is a microcrystalline phase having an average crystal grain size of 30 nm or less mainly composed of Co or Fe and Co when Co is selected as the element A or Fe and Co are selected as the element A.

It is considered that the amorphous phase 7 contains a large amount of an oxide of the element M and also contains FeO and Fe ₂ O ₃ . When the element M is Hf, it is considered that the amorphous phase 7 contains a large amount of HfO ₂ .

  The film structure of the Fe-MO film 6 is different from that of the nano granular alloy. The nano-granular has a configuration in which a grain boundary material such as an insulator is interposed between the ferromagnetic fine particles. On the other hand, the amorphous phase 7 in the Fe-MO film 6 does not exist only at the grain boundaries between the microcrystalline phases 8. As described above, the Fe-MO film 6 has a mixed phase structure in which the microcrystalline phase 8 is scattered in the amorphous phase 7. Even in the X-ray diffraction spectrum described later, it can be clearly seen that the amorphous phase 7 exists.

  The amorphous phase 7 contained in the Fe—M—O film 6 is preferably about 20 to 80% by volume ratio.

  The Fe-MO film 6 described above is excellent in soft magnetic characteristics. For example, the real part μ ′ of the complex relative magnetic permeability can be 50 or more, preferably 300 or more, more preferably 400 or more, and the specific resistance ρ is 200 (μΩ · cm) or more, preferably 300 (μΩ · cm) or more. Can be set.

  In the present embodiment, the film thickness T2 (see FIG. 2) of the Fe-MO film 6 can be formed thinner than the conventional magnetic sheet for RFID in which magnetic powder is dispersed in a resin. Specifically, it is not necessary to disperse the magnetic material in the resin, and the film can be formed only with the Fe-MO film 6, so that the film thickness T2 can be formed with a film thickness smaller than 100 μm. Further, as described above, the real part μ ′ of the complex relative magnetic permeability of the Fe—M—O film 6 can be increased to 50 or more, preferably 300 or more, or 400 or more. Therefore, as shown in the experiment described later, the Fe— Even if the film thickness T2 of the MO film 6 is sufficiently smaller than 100 μm, the real part μ ′ of the complex relative permeability that affects the attenuation of the received signal × the film thickness t of the magnetic film can be made relatively large. In the present embodiment, even if the film thickness T2 of the Fe—MO film 6 is set to a thin film thickness of 0.5 to 15 μm, the attenuation amount can be effectively reduced. Preferably, the film thickness T2 is 10 μm or more.

  In the present embodiment, a flexible resin sheet 5 is used as a substrate for supporting the Fe-MO film 6. Thereby, the magnetic sheet 4 can be brought into close contact between the RFID tag 2 and the metal member 3. Further, even when the magnetic sheet 4 is bent, the magnetic sheet 4 can be bent appropriately, and the Fe-MO film 6 includes an amorphous phase 7. Therefore, the Fe-MO film 6 is made of resin. Even when the sheet 5 is deformed from a flat shape, the Fe-MO film 6 is not easily damaged such as cracking. A rigid glass substrate or the like can also be used as the substrate.

  Further, as described above, since the heat treatment is not performed on the Fe-MO film 6, the material of the resin sheet 5 that supports the Fe-MO film 6 may not be particularly limited. That is, the selectivity of the resin sheet 5 can be increased. Further, since there is no thermal influence on the resin sheet 5, it is possible to obtain the dimensional stability of the magnetic sheet 4 with higher accuracy than before. A thermoplastic resin can be used for the resin sheet 5, and among them, PPS (polyphenylene sulfide) having excellent heat resistance is suitable, but PET (polyethylene terephthalate), PEN (polyethylene naphthalate), amirado (all Aromatic polyamide), polyimide and the like can also be used.

  The film thickness T3 of the resin sheet 5 is preferably about 0.01 to 0.05 mm.

  In the present embodiment, as shown in FIG. 1, a magnetic sheet 4 in which an Fe—M—O film 6 is sputter-deposited on a resin sheet 5 is inserted between the RFID tag 2 and the metal member 3. Then, the magnetic flux H from the read / dryer 10 passes through the Fe-MO film 6, and a reflux magnetic flux is formed between the RFID device 1 and the read / dryer 10. As a result, the amount of attenuation of the signal output received by the antenna of the RFID tag 2 can be reduced, and for example, the RFID characteristics at 13.56 MHz can be effectively improved. Further, in the present embodiment, the range of the communication distance L1 between the RFID device 1 and the reader / writer 10 can be expanded. Specifically, even if the communication distance L1 is set to a range of 10 to 50 mm, wireless communication is appropriately performed. Communication is possible.

  When the magnetic sheet 4 is inserted between the metal member 3 and the RFID tag 2, there is no particular limitation as to which side the magnetic sheet 5 and the Fe-MO film 6 face the metal member 3 or the RFID tag 2. For example, the Fe-MO film 6 is brought into contact with the metal member 3 through an adhesive layer (not shown), and the magnetic sheet 5 is brought into contact with the RFID tag 2 through an adhesive layer (not shown). Let

  In the present embodiment, as described above, a mixed phase of the amorphous phase 7 shown in FIG. 3 and the microcrystalline phases 8 interspersed in the amorphous phase 7 without heat treatment of the Fe-MO film 6. A structure can be obtained, and a real part μ ′ (specifically, 50 or more, preferably 300 or more, 400 or more) having a complex relative permeability that is excellent in soft magnetic properties and sufficiently large as a magnetic sheet for RFID can be obtained. It is possible to obtain a higher specific resistance ρ (specifically, 200 (μΩcm) or more, preferably 300 (μΩcm) or more).

  Further, in the present embodiment, a film structure of the amorphous phase 7 and the microcrystalline phases 8 scattered in the amorphous phase 7 can be obtained more appropriately without heat treatment. As described above, it is possible to obtain a real part μ ′ of complex relative permeability of 300 or more, preferably 400 or more, and a specific resistance ρ of 200 (μΩcm) or more, preferably 300 (μΩcm) or more.

  As described above, in this embodiment, Hf, Al, Zr, or the like can be used as the element M. At this time, when the element M is Zr, it was found by experiments described later that a real part μ ′ having a high complex relative permeability, an imaginary part μ ″ having a low complex relative permeability, and a low film stress can be obtained. According to this experiment, the real part μ ′ of the complex relative permeability can be about 800, the imaginary part μ ″ of the complex relative permeability can be about 50, and the film stress can be about 80 (MPa). Therefore, it is suitable when the magnetic film 6 made of FeZrO having excellent soft magnetic characteristics and low film stress is directly formed on the housing cover or on a soft material such as a glass epoxy substrate or a resin sheet. In addition, a magnetic film can be formed. In particular, even if a magnetic film is formed only on one side of a soft substrate, the magnetic sheet 4 does not become a roll because the film stress is low, the handling of the magnetic sheet 4 is easy, and the material cost is low. The reason why the material cost can be reduced is that the magnetic film only needs to be formed on one side of the substrate as described above (if the film stress is large, the magnetic film is formed on both sides of the substrate This is because Zr is sufficiently cheaper than Hf or the like.

  Moreover, the magnetic sheet 4 shown in FIG. 2 can be used for electromagnetic wave suppression. The magnetic sheet 4 for suppressing electromagnetic waves varies depending on the usage and range of use. For example, the horizontal dimension L1 is formed within a range of 10 mm or more, and the vertical dimension L2 is formed within a range of 10 mm or more.

  The composition ratio and film structure of the Fe—M—O film 6 formed on the resin sheet 5 are as described above.

  The magnetic sheet 4 for suppressing electromagnetic waves, in which the Fe-M-O film 6 having a mixed phase structure of the amorphous phase 7 and the microcrystalline phase 8 is formed on the resin sheet 5 by sputtering, has the above-described Fe-M in a frequency band of 100 MHz or more. The imaginary part μ ″ of the complex relative permeability of the −O film 6 can be made 80 or more, and the specific resistance ρ of the Fe—MO film 6 can be made 300 (μΩ · cm) or more, and it is excellent in a thin sheet thickness. It is possible to obtain the radio wave absorption characteristics.

  In the present embodiment, even if the film thickness T2 (see FIG. 2) of the Fe-MO film 6 is thinned to about 0.5 μm, the imaginary part of the complex relative permeability in a frequency band of 100 MHz or more. μ ″ can be increased to 80 or more.

  The film thickness T3 (see FIG. 2) of the resin sheet 5 is about 10 to 50 μm, and therefore the total thickness T1 of the magnetic sheet 4 can be set within the range of 10.5 to 65 μm. As described above, since the total thickness T1 of the magnetic sheet 4 for suppressing electromagnetic waves can be reduced, for example, even if the magnetic sheet 4 is adhered to the wall surface inside the housing of a small device such as a mobile phone, the installation of the components is obstructed. do not become.

  In the present embodiment, a flexible resin sheet 5 is used as a substrate for supporting the Fe-MO film 6. Therefore, for example, the magnetic sheet 4 can be appropriately attached on a flat surface or a curved surface with unevenness. Further, since the Fe-MO film 6 includes the amorphous phase 7, even when the Fe-MO film 6 is deformed from the planar shape together with the resin sheet 5, the Fe-MO film 6 is cracked or the like. Less susceptible to damage.

The magnetic sheet 4 shown in FIG. 2 can be formed on the resin sheet 5 by physical vapor deposition. In the present embodiment, when the Fe—M—O film 6 is formed on the resin sheet 5, the gas pressure of the mixed gas of an inert gas (for example, Ar) and O ₂ gas is in the range of 0.5 mTorr to 6 mTorr. Adjust with. Thus, a film comprising an amorphous phase containing a compound of elements M and O and a microcrystalline phase having an average crystal grain size of 30 nm or less mainly composed of one or two kinds selected from Fe or Co scattered in the amorphous phase. It is possible to form a structure. As shown in the experiment described later, when the gas pressure is increased too much, a sharp and clear peak corresponding to the bcc phase of Fe does not appear in the X-ray diffraction spectrum, and it becomes broad, and the film structure becomes amorphous as a whole. I understood it. It was also found that both the real part μ ′ and the imaginary part μ ″ of the complex relative permeability are lowered.

  When the gas pressure is adjusted within the range of 0.5 mTorr to 6 mTorr, a sharp and clear peak corresponding to the bcc phase of Fe appears in the X-ray diffraction spectrum, and a mixed phase structure of the amorphous phase 7 and the microcrystalline phase 8 can be obtained. Both the real part μ ′ and the imaginary part μ ″ of the complex relative permeability can obtain high soft magnetic characteristics.

  Such a relationship between the film forming conditions, the film structure, and the magnetic characteristics is unique to the high resistance soft magnetic film. For example, CoZrNb or the like is an amorphous film, but can obtain soft magnetic characteristics.

  As the physical vapor deposition method, RF or DC parallel plate magnetron sputtering method (MT method), DC facing target sputtering method (FTS method), RF facing target sputtering method, vapor deposition method, reactive plasma vapor deposition method, and the like can be presented.

(Experiment of RFID characteristics)
Experiments on RFID characteristics (attenuation of received signals) were conducted.
FIG. 4A shows a reference configuration. As shown in FIG. 4A, the communication distance L2 between the transmission antenna 20 and the reception antenna 21 was 28 mm. The transmitting antenna 20 and the receiving antenna 21 were formed on a substrate having a plane size of 55 mm × 85 mm and a thickness of 0.55 mm. The transmitting antenna 20 and the receiving antenna 21 were formed in a planar pattern having a maximum outer edge dimension of 30 mm × 30 mm and 3 turns.

In FIG. 4B, a metal plate 22 is added to the reference configuration of FIG. 4A, and the metal plate 22 is transmitted to the transmission antenna 21 as shown in FIG. It was provided on the side opposite to the surface facing the antenna 20. The metal plate 22 was made of Al and had a plane size of 55 mm × 85 mm and a thickness of 2 mm. An Al ₂ O ₃ film having a thickness of 0.1 μm was formed between the metal plate 22 and the receiving antenna 21.

  In FIG. 4C, a magnetic sheet 23 is inserted between the metal plate 22 and the receiving antenna 21 with respect to the configuration of FIG.

  As a comparative example, the magnetic sheet 23 has Alps Electric's trade names 20R (thickness 100 μm, 200 μm), 40R (thickness 100 μm, 200 μm), 60R (thickness 100 μm), 80R (thickness 100 μm) ( Comparative Examples 1 to 6) and NEC TOKIN (product name) R4N (01), FK1 (01) (Comparative Examples 7 and 8: both 100 μm thick) were used.

Further, a magnetic sheet in which Fe _{50.19 at%} Hf _{13.72 at%} O _{36.09 at%} having a film thickness of 0.78 μm, 3.3 μm, 10 μm, and 15 μm is formed on a borosilicate glass substrate having a thickness of 0.55 _mm by sputtering. 23 was formed. An Fe—Hf alloy was used as the target. A SPF-730 magnetron sputtering apparatus manufactured by Canon Anelva was used as the sputtering apparatus. As sputtering conditions, the Ar gas flow rate is 50 sccm, the Ar + 5% O ₂ gas flow rate is 25 sccm, R
F power was 600 W, gas pressure was 3 mTorr, T / S = 0%, and substrate indirect cooling. Note that no heat treatment was performed on the Fe—Hf—O film.

  For each sample, the output value of the received signal from the receiving antenna 21 at 13.56 MHz was measured using a spectrum analyzer (manufactured by Anritsu Co., Ltd., model: MS2601B).

The attenuation (dBm) of the received signal is (output value of the received signal in the reference configuration in FIG. 4A) − (output of the received signal in each configuration in FIG. 4B or 4C). Value). A smaller attenuation means that the receiving antenna 21 receives the electromagnetic wave from the transmitting antenna 20 without leakage and has better RFID characteristics.
The sample used in the experiment, the signal output from the receiving antenna, and the attenuation are shown in Table 1 below.

  Based on Table 1, sample no. The relationship between the film thicknesses of 2 to 14 magnetic films and the attenuation was examined. The experimental results are shown in FIG.

  In addition, sample No. The real part μ ′ × complex relative permeability of 2 to 14 × the film thickness t (hereinafter referred to as μ ′ × t) of the magnetic film was examined and listed in the following Table 2 together with the magnetic film thickness and attenuation.

  Moreover, based on Table 2, the relationship between μ ′ × t and the attenuation amount of sample Nos. 2 to 14 was examined. The experimental results are shown in FIG.

  As shown in FIGS. 5 and 6, in the configuration of FIG. 4B in which a magnetic film is not provided between the receiving antenna 21 and the metal plate 22, the amount of attenuation is very large. This is an influence of a demagnetizing field caused by an eddy current generated in the metal plate 22.

  In addition, in the comparative example in which the magnetic sheet is inserted between the receiving antenna 21 and the metal plate 22 as shown in FIGS. 5 and 6, the attenuation can be reduced as compared with the configuration of FIG. The film thickness was 100 μm to 200 μm, and if the magnetic sheet was inserted, the RFID device could not be made thinner.

  On the other hand, in the form in which the Fe—Hf—O sputtered film is provided between the receiving antenna 21 and the metal plate 22, the attenuation can be made smaller than that in the form of FIG. 4 (b), and the Fe—Hf—O sputtered film. Was made sufficiently thinner than the magnetic film of the comparative example. Specifically, as shown in Tables 1 and 2, the film thickness of the Fe—Hf—O sputtered film could be about 1/10 of the film thickness of the magnetic film of the comparative example.

  As shown in FIGS. 5 and 6, in order to obtain an attenuation amount equal to or less than that of the comparative example, the film thickness of the Fe—Hf—O sputtered film is approximately 0.5 μm or more, preferably 0.78 μm or more, more preferably 10 μm. It turned out that it is suitable for the above.

  As shown in FIG. 6, it was found that the attenuation amount of the received signal can be gradually decreased as μ ′ × t is increased. Therefore, as the thickness of the Fe—Hf—O sputtered film increases, the attenuation can be made closer to zero. However, in order to contribute to the reduction in the thickness of the RFID device, the Fe—Hf—O sputtered film can be reduced. The maximum thickness was 15 μm. That is, the preferable film thickness range of the Fe—Hf—O sputtered film was set to 0.5 to 15 μm. A preferable range of μ ′ × t was 402 (μm) to 7895 (μm).

  Next, an Fe—Hf—O film is formed on the substrate by sputtering, and the composition ratio of the element O and the real part μ ′ (13.56 MHz) and the imaginary part μ ″ (13.56 MHz) of the complex relative permeability. I investigated the relationship.

The sputtering apparatus, target, and sputtering conditions (other than the O ₂ flow ratio) used for the sputtering of the Fe—Hf—O film are the same as in the above experiment. An Fe—Hf—O film of each sample was formed with a film thickness of approximately 1 μm. In addition, no heat treatment was applied to each sample. In the experiment, the composition ratio of the element O incorporated in Fe—Hf—O is changed by changing the O ₂ flow rate ratio, and the real part μ ′ (13.56 MHz) of the complex relative permeability for each sample and The imaginary part μ ″ (13.56 MHz) was measured. For the measurement of μ ′ and μ ″, PMF-3000 (network analyzer HP4396B manufactured by Ryowa Denshi Co., Ltd., high-frequency transmission coil using a shielded loop coil as the detection unit) was measured. Magnetic susceptibility measurement method). The experimental results are shown in Table 3 below and FIG.

  As shown in Table 3 and FIG. 7, it is found that the real part μ ′ (13.56 MHz) of the complex relative permeability can be increased to 400 or more by setting the composition ratio of the element O in the range of 27.08 to 47 at%. It was. It was also found that the imaginary part μ ″ (13.56 MHz) of the complex relative permeability can be suppressed to 22 or less.

  Further, the specific resistance ρ of the Fe—Hf—O film shown in Table 3 was examined. Further, the saturation magnetic flux density Bs and the coercive force Hc of the Fe—Hf—O film were also examined. The relationship between the composition ratio of the element O and the specific resistance ρ is shown in Table 4 and FIG. 8 below, the relationship between the composition ratio of the element O and the saturation magnetic flux density Bs is shown in FIG. 9, and the composition ratio of the element O and the coercive force Hc These relationships are shown in FIG. In Table 4 and FIG. 8, Hf composition ratio / (Fe composition ratio + Hf composition ratio) (%) is also shown.

  As shown in Table 4 and FIG. 8, it was found that when the composition ratio of the element O was set in the range of 27.08 to 47 at%, a high specific resistance ρ of 300 (μΩcm) or more could be obtained.

  Further, as shown in FIGS. 9 and 10, when the composition ratio of the element O is set in the range of 27.08 to 47 at%, the saturation magnetic flux density Bs can be increased, the coercive force Hc can be decreased, and excellent soft magnetic characteristics can be obtained. It turns out that it is obtained.

  Subsequently, an X-ray diffraction spectrum of each Fe—Hf—O film having the composition ratio of element O shown in Table 3 of 6.41 at%, 27.08 at%, and 66.91 at% was obtained. Neither is heat-treated. The result is shown in FIG.

  When the composition ratio of element O was 6.41 at%, the amorphous phase became the main phase, while the presence of the bcc phase of Fe could not be confirmed. Further, in the X-ray diffraction spectrum of the Fe—Hf—O film in which the composition ratio of element O is 66.91 at%, the peak of the bcc phase of Fe is not seen, and the peak of HfO, FeO and the amorphous phase (Fe or Fe Hf oxide) was present.

  On the other hand, the X-ray diffraction spectrum of the Fe—Hf—O film in which the composition ratio of element O is 27.08 at% shows a sharp and clear peak corresponding to the bcc phase of Fe and a frequency close to that of Hf or Fe oxide. A broad peak was observed at the corner. From this result, the film structure of the Fe—Hf—O film in which the composition ratio of element O is 27.08 at% is an amorphous phase and a bcc microcrystalline phase mainly composed of Fe interspersed in the amorphous phase. It was found to be a multiphase structure.

  Thus, a mixed phase structure of an amorphous phase and a bcc microcrystalline phase mainly composed of Fe interspersed in the amorphous phase can be obtained without performing heat treatment on the Fe—Hf—O film. all right. Such a mixed phase structure is excellent in soft magnetic characteristics by including a microcrystalline phase and can increase the specific resistance ρ due to the presence of an amorphous phase. Therefore, in the Fe—Hf—O film in which the composition ratio of the element O is in the range of 27.08 to 47 at% based on the experimental results shown in FIGS. 7 and 8, the amorphous phase and the amorphous phase are included in the amorphous phase without heat treatment. It can be presumed that it has a mixed phase structure with bcc microcrystalline phase mainly composed of scattered Fe. In the above experiment, the Fe—Hf—O film was formed on the borosilicate glass substrate, but it goes without saying that the same effect can be obtained even if the Fe—Hf—O film is formed on the resin sheet.

(Noise suppression effect experiment)
Experiments on radiation noise suppression effect (transmission attenuation) and conduction noise suppression effect (transmission attenuation rate: P (loss) / P (in)) were conducted.

  FIG. 12 is a diagram illustrating a noise suppression evaluation apparatus. As shown in FIG. 12, the noise suppression evaluation apparatus includes an evaluation board 11 having a conductive pattern 16, a signal source 13 for sending a signal to the conductive pattern 16, and reception loop antennas 14a and 14b for receiving radiation noise. The control unit 15 mainly evaluates the radiation noise suppression effect and the conduction noise suppression effect.

  The magnetic sheet 4 is disposed on the evaluation substrate 11 so as to cover the conductive pattern 16. When the magnetic sheet 4 is disposed on the conductive pattern 16, a region where the magnetic sheet 4 is not present and a region where the magnetic sheet 4 is present are formed. Receive radiated noise in the area. In FIG. 12, the reception loop antenna 14a receives radiation noise in a region where the magnetic sheet 4 does not exist, and the reception loop antenna 14b receives radiation noise in a region where the magnetic sheet 4 exists. Thereby, the noise suppression effect for the reflection dependence of the area where the magnetic sheet 4 does not exist can be evaluated by the radiation noise received by the reception loop antenna 14a, and the radiation noise received by the reception loop antenna 14b can be evaluated. In addition, it is possible to evaluate the noise suppression effect of the transmission attenuation in the region where the magnetic sheet 4 is present.

  The control unit 15 is a processing unit that evaluates the radiation noise suppression effect and the conduction noise suppression effect. The radiation noise suppression effect can be evaluated by a spectrum analyzer, and the conduction noise suppression effect can be evaluated by a network analyzer. The receiving loop antennas 14a and 14b are electrically connected to the spectrum analyzer, and the conductive pattern 16 of the evaluation board 11 is electrically connected to the network analyzer.

  As shown in FIG. 12, the magnetic sheet 4 is arranged on the conductive pattern 16 formed on the evaluation substrate, and in this state, when a signal is output to the conductive pattern 16, the conduction noise suppression effect of the signal passing through the conductive pattern 16 While measuring (transmission attenuation factor), the radiation noise suppression effect of each of the region where the magnetic sheet 4 is not present and the region where the magnetic sheet 4 is present is measured.

  First, the reflection dependence of the radiation noise suppression effect is measured by the reception loop antenna 14a in a state where the magnetic sheet 4 is not disposed on the evaluation board 11, and the transmission attenuation of the radiation noise suppression effect is measured by the reception loop antenna 14b. Next, the reflection dependency of the radiation noise suppression effect is measured by the reception loop antenna 14a in a state where the magnetic sheet 4 is disposed on the evaluation board 11, and the transmission attenuation of the radiation noise suppression effect is measured by the reception loop antenna 14b. Then, the radiation noise for the reflection dependency is obtained by subtracting the radiation noise suppression effect for the reflection dependency when there is no magnetic sheet 4 from the radiation noise suppression effect for the reflection dependency when the magnetic sheet 4 is present. The radiation noise suppression effect for the transmission attenuation is obtained by subtracting the radiation noise suppression effect for the transmission attenuation in the absence of the magnetic sheet 4 from the radiation noise suppression effect for the transmission attenuation in the case. The radiation noise suppression effect (transmission attenuation) can be measured by adding the effect and the radiation noise suppression effect for the required transmission attenuation. In addition, the conduction noise suppression effect (transmission attenuation factor) can be measured by receiving the signal transmitted from the signal source 13 by the control unit 15.

  The radiation noise suppression effect (transmission attenuation amount) and the conduction noise suppression effect (transmission attenuation factor) can be obtained by the following equations.

Radiation noise suppression effect (transmission attenuation) (dB) = S31 (when there is a magnetic sheet 41) -S31 (when there is no magnetic sheet 4)
Conductive noise suppression effect (transmission attenuation factor) (P (loss) / P (in)) = 1− (S11) ² − (S21) ²

In the experiment, a magnetic sheet in which Fe _{50.19 at%} Hf _{13.72 at%} O _{36.09 at%} with a film thickness of 3 μm was sputter-deposited on a borosilicate glass substrate having a thickness of 0.55 mm and a width of 30 mm × length of 40 mm. 4 (Example) was formed. An Fe—Hf alloy was used as the target. As a sputtering apparatus, an SPF-730 magnetron sputtering apparatus manufactured by Canon Anelva was used. As sputtering conditions, the Ar gas flow rate was 50 sccm, the Ar + 5% O ₂ gas flow rate was 25 sccm, the RF power was 600 W, the gas pressure was 3 mTorr, T / S = 0%, and indirect substrate cooling. Note that no heat treatment was performed on the Fe—Hf—O film.

  In the noise suppression evaluation apparatus shown in FIG. 12, a φ4 mm micro loop antenna is used as a receiving loop antenna, N3383A (manufactured by Agilent Technologies) is used as a network analyzer, and 8595E (manufactured by Agilent Technologies) is used as a spectrum analyzer. ) Was used.

  As an example, the magnetic sheet 4 is placed on the evaluation board so that the Fe-Hf-O film side of the magnetic sheet 4 is opposed to the conductive pattern 16 and the conductive pattern 16 is positioned at the center of the magnetic sheet 4. 11 was installed. A weight (about 100 g) was placed on the magnetic sheet 4. Then, a radiation noise suppression effect (transmission attenuation) at 500 MHz was determined, and a conduction noise suppression effect (transmission attenuation rate) was determined.

  Further, as a comparative example, a magnetic sheet (trade name: FK1 (01)) manufactured by NEC TOKIN (manufactured) is installed on the conductive pattern 16 to suppress radiation noise at 500 MHz (transmission attenuation). Amount) and the conduction noise suppression effect (transmission attenuation factor).

  FIG. 13 is an experimental result of the radiation noise suppression effect (transmission attenuation amount) of the example and the comparative example, and FIG. 14 is an experimental result of the conduction noise suppression effect (transmission attenuation factor) of the example and the comparative example.

  As shown in FIG. 13, in the example, the transmission attenuation amount (absolute value) is larger than that of the comparative example, and it has been found that the example can attenuate the noise more appropriately than the comparative example.

  Further, from the experimental results shown in FIG. 14, it was found that the noise suppression effect was greater in the example in a wider frequency band than in the comparative example.

  Subsequently, the frequency dependence of the real part μ ′ and the imaginary part μ ″ of the complex relative permeability in the magnetic sheet 4 of the above-described example was obtained. The result is shown in FIG.

  As shown in FIG. 15, it was found that the imaginary part μ ″ of the complex relative permeability of the electromagnetic wave absorbing sheet 1 can be 80 or more in a frequency band of 100 MHz or more.

  In the above experiment, the Fe—Hf—O film was formed on the borosilicate glass substrate, but it goes without saying that the same effect can be obtained even if the Fe—Hf—O film is formed on the resin sheet.

(Gas pressure experiment)
An Fe—Hf—O film was formed on the substrate by sputtering using an RF parallel plate magnetron sputtering method (MT method) and a DC facing target sputtering method (FTS method).

First, an Fe—Hf—O film was formed by sputtering using the MT method. A borosilicate glass substrate was used as the substrate. The target was an Fe—Hf alloy. A SPF-730 magnetron sputtering apparatus manufactured by Canon Anelva was used as the sputtering apparatus. As sputtering conditions, the Ar gas flow rate is 50 sccm, the Ar + 5% O ₂ gas flow rate is 25 sccm, the O ₂ / (Ar + O ₂ ) flow rate ratio is 1.67%, the RF power is 600 W, T / S = 0%, and indirect substrate cooling. did. An Fe—Hf—O film was formed to a thickness of 1 μm. The gas pressure was adjusted by the orifice angle.

No heat treatment was performed on the Fe—Hf—O film. The gas pressure of the mixed gas of Ar and O ₂ was changed, and the relationship between the gas pressure and the real part μ ′ and the imaginary part μ ″ of the complex relative permeability of the Fe—Hf—O film was examined.

Subsequently, an Fe—Hf—O film was formed by sputtering using the FTS method. A Si substrate was used as the substrate. Moreover, the Fe-Hf alloy target was used for the target. An RF facing target sputtering apparatus was used as the sputtering apparatus. As sputtering conditions, the power was 300 W, 5500 W (high power), and a mixed gas of Ar gas and O ₂ gas was used, and the O ₂ / (Ar + O ₂ ) flow rate ratio was set to 0% to 26.3%. An Fe—Hf—O film was formed to a thickness of 2 μm. The gas pressure was set by adjusting the gas flow rate.

No heat treatment was performed on the Fe—Hf—O film. The gas pressure of the mixed gas of Ar and O ₂ was changed, and the relationship between the gas pressure and the real part μ ′ and the imaginary part μ ″ of the complex relative permeability of the Fe—Hf—O film was examined.

  FIG. 16 shows the experimental results. FIG. 17 shows the relationship between the gas pressure and the composition ratio of the Fe—Hf—O film.

  As shown in FIG. 17, it was found that there was no significant difference in the composition ratio with the Fe—Hf—O film when the gas pressure was 6 mTorr and 9 mTorr.

  However, as shown in FIG. 16, it was found that when the gas pressure is higher than 6 mTorr, the real part μ ′ and the imaginary part μ ″ of the complex relative permeability are greatly reduced.

  Next, the relationship between the gas pressure and the X-ray diffraction spectrum of the Fe—Hf—O film was examined. For the measurement, a sample in which an Fe—Hf—O film was formed by the MT method in the above experiment was used. The experimental result is shown in FIG.

  As shown in FIG. 18, in the sample with a gas pressure of 9 mTorr, it was found that the peak of bcc-Fe (110) is broad and has a structure close to amorphous. In addition, the experimental results at gas pressures of 6.5 mTorr, 7 mTorr, and 8 mTorr also showed that the bcc-Fe (110) peak was broad, although not as much as when the gas pressure was 9 mTorr.

  Next, the relationship between the gas pressure when the Fe—Hf—O film was formed mainly by the FTS method and the X-ray diffraction spectrum of the Fe—Hf—O film was examined. Note that the Fe—Hf—O film in the FTS method and MT method used for the measurement in FIG. 19 is the same as that used in the experiment in FIG.

  As shown in FIG. 19, even in the FTS method, when the gas pressure was 9.8 mTorr, the bcc-Fe (110) peak was broad, indicating that the structure was close to amorphous. Further, when the gas pressure was set to 6 mTorr in the FTS method, it seemed that the peak of bcc-Fe (110) did not appear, but the peak actually appeared, indicating soft magnetism.

  Subsequently, Fe—Hf—O films having various composition ratios were formed by sputtering using the FTS method. As shown in Table 5 below, the gas pressure was changed to 0.7 mTorr, 1.0 mTorr, and 3.0 mTorr.

  As shown in Table 5, even when the element O is reduced to 6.85 at%, it is possible to obtain excellent soft magnetic characteristics in which both the real part μ ′ and the imaginary part μ ″ of the complex relative permeability are high. In the above experiment, the Fe—Hf—O film was formed on the borosilicate glass substrate, but it goes without saying that the same effect can be obtained even if the Fe—Hf—O film is formed on the resin sheet.

  As described above, in the Fe—Hf—O film, the composition ratio c of the element O is in the range of 6.85 to 47 at%, the composition ratio b of the element Hf is in the range of 11.40 to 15.74 at%, and the balance Is the composition ratio a of the element Fe, and preferably satisfies the relationship of a + b + c = 100 at%. Thereby, the real part μ ′ of the complex relative permeability can be set to 50 or more and the specific resistance ρ can be set to 200 (μΩ · cm) or more. More preferably, the composition ratio c of the element O is 27.08 to 47 at%, and the composition ratio b of Hf is 11.40 to 15.74 at%. Thereby, the real part μ ′ of the complex relative permeability can be set to 400 or more and the specific resistance ρ can be set to 300 (μΩ · cm) or more.

(Experiment of Fe-Al-O film and Fe-Zr-O film)
A Fe—Al—O film in which the composition ratio of element O and the composition ratio of Al was changed was sputtered on the substrate, and the real part μ of the complex relative permeability of each Fe—Al—O film obtained at this time ′ (13.56 MHz), imaginary part μ ″ (13.56 MHz) and the like were examined.

  In the experiment, an Fe—Al—O film was formed by the RF parallel plate conventional sputtering method or the DC facing target sputtering method (FTS method). The gas pressure during film formation was 4 mTorr for the former and 3 mTorr for the latter.

  Subsequently, an Fe—Zr—O film in which the composition ratio of element O and the composition ratio of Zr was changed was formed on the substrate by sputtering, and the complex relative permeability of each Fe—Zr—O film obtained at this time was determined. The real part μ ′ (13.56 MHz) and the imaginary part μ ″ (13.56 MHz) were examined.

As described above, the composition ratio of element O in the Fe—Zr—O film was changed by changing the O ₂ / (Ar + O ₂ ) flow rate ratio as shown in FIGS. 20 and 21 show the real part of the complex relative permeability when the gas pressure and the O ₂ / (Ar + O ₂ ) flow rate ratio are changed when the Fe—Zr—O film is formed by the MT method. It is an experimental result of μ ′ and film stress.

In the experiment, an Fe—Zr—O film was formed by RF parallel plate magnetron sputtering (MT method). The gas pressure during film formation was 3 mTorr.
The experimental results are shown in Table 6 below.

Table 6 also shows the experimental results of the Fe—Hf—O film already described above.
As shown in Table 6, for the Fe—Al—O film, the complex ratio is controlled by restricting the composition ratio of element O to 6.99 to 16.75 at% and the Al composition ratio to 9.79 to 21.38 at%. It has been found that the specific resistance (resistivity) can be increased to 200 (μΩcm) or higher with the real part μ′50 or higher of the magnetic permeability.

  More preferably, the composition ratio c of the element O is 12.20 to 16.75 at%, and the Al composition ratio b is 12.68 to 15.17 at%. Thus, it was found that the real part μ ′ of the complex relative permeability can be set to 300 or more and the specific resistance ρ can be set to 300 (μΩ · cm) or more.

  Further, as shown in Table 6, for the Fe—Zr—O film, the composition ratio of element O is within the range of 8.11 to 9.29 at%, and the composition ratio of Zr is within the range of 7.95 to 8.36 at%. It was found that the real part μ ′ of the complex relative permeability can be set to 100 or more and the specific resistance ρ can be set to 250 (μΩ · cm) or more.

  More preferably, the composition ratio of element O is 8.11 to 9.27 at%, and the composition ratio b of Zr is 7.95 to 8.36 at%. Thus, it was found that the real part μ ′ of the complex relative permeability can be set to 800 or more and the specific resistance ρ can be set to 250 (μΩ · cm) or more.

  As shown in Table 6 and FIGS. 20 and 21, the Fe—Zr—O film has a real part μ ′ having a high complex relative permeability and a low complex relative permeability compared to the Fe—Hf—O film and the Fe—Al—O film. It was found that an imaginary part μ ″ of magnetic susceptibility and low film stress can be obtained. Specifically, a real part μ ′ of complex relative permeability is about 800, an imaginary part μ ″ of complex relative permeability is about 50, It was also found that the film stress could be about 80 (MPa). Therefore, when a Fe—Zr—O film is used, even if a magnetic film is formed on only one side of a soft base material, the magnetic sheet does not become a roll because the film stress is low, and handling of the magnetic sheet becomes easy. In addition, it has been found that the material cost can be reduced by forming the film on one side and using Zr which is cheaper than Hf or the like.

Next, the relationship of the X-ray diffraction spectrum of the Fe _{73.22 at%} Al _{13.31 at%} O _{13.47 at%} film was examined. The experimental results are shown in FIG.

  As shown in FIG. 22, a sharp and clear peak corresponding to the bcc phase of Fe was observed. On the other hand, a broad peak indicating amorphous was not observed. However, it can be presumed that the Fe—Al—O film also has a mixed phase structure of a bccFe microcrystalline phase and an amorphous phase for the following reason.

First, as shown in FIG. 22, no amorphous broad peak is observed in the amorphous Al ₂ O ₃ film. Further, as shown in the X-ray diffraction spectrum of the Fe—Al—O film, no peak showing a clear crystal other than the peak corresponding to the bcc phase of Fe is observed. Further, the interplanar spacing d of α-Fe (110) increases when the Fe—Al film (ie, there is no element O) spreads because Al replaces the Fe lattice. In the case of a film, Al is preferentially bonded to O, or Al does not enter the Fe lattice, and an amorphous broad peak is clearly observed (an X-ray diffraction spectrum is shown below). ) Is almost the same spacing as. Considering the above comprehensively, it can be presumed that amorphous exists also in the Fe—Al—O film.

FIG. 23 is an X-ray diffraction spectrum of an Fe _{83.58 at%} Zr _{8.31 at%} O _{8.11 at%} film. As shown in FIG. 23, a sharp and clear peak corresponding to the bcc phase of Fe and a broad peak at a diffraction angle close to that of Zr or Fe oxide were observed. From this result, it was found that the film structure of the Fe—Zr—O film was a mixed phase structure of an amorphous phase and a bcc microcrystalline phase mainly composed of Fe scattered in the amorphous phase.

Schematic diagram of RFID device and reader / writer The perspective view of the magnetic sheet of the embodiment of the present invention, Schematic diagram of the film structure of the Fe-MO film, It is each block diagram of the sample used for the measurement of the attenuation amount of a received signal, (a) is a basic block diagram, (b) is a metal on the opposite side to the opposing surface with the transmitting antenna of (a). (C) is a configuration diagram in which a magnetic sheet is inserted between the receiving antenna of (b) and the metal plate, A graph showing the relationship between the attenuation and the thickness of the magnetic film inserted between the receiving antenna and the metal plate, A graph showing the relationship between the real part μ ′ of the complex relative permeability of the magnetic film × the thickness t of the magnetic film and the attenuation; A graph showing the relationship between the composition ratio of the element O of the Fe—Hf—O film and the real part μ ′ and the imaginary part μ ″ of the complex relative permeability; A graph showing the relationship between the composition ratio of the element O of the Fe—Hf—O film and the specific resistance ρ; A graph showing the relationship between the composition ratio of the element O of the Fe—Hf—O film and the saturation magnetic flux density Bs; A graph showing the relationship between the composition ratio of the element O of the Fe—Hf—O film and the coercive force Hc of the Fe—Hf—O film; X-ray diffraction spectrum of each Fe—Hf—O film in which the composition ratio of the element O is 6.41 at%, 27.08 at%, 66.91 at%, Configuration diagram of the noise suppression evaluation device, Experimental results of radiation noise suppression effect (transmission attenuation) of Example (Fe—Hf—O film) and Comparative Example (conventional magnetic sheet), Experimental results of conductive noise suppression effect (transmission attenuation factor) of Example (electromagnetic wave absorbing sheet using Fe-Hf-O film) and Comparative Example (conventional magnetic sheet), A graph showing the frequency dependence of the real part μ ′ and the imaginary part μ ″ of the complex relative permeability in the electromagnetic wave absorbing sheet of the example, A graph showing the relationship between the gas pressure and the real part μ ′ and the imaginary part μ ″ of the complex relative permeability of the Fe—Hf—O film when the gas pressure of the mixed gas of Ar and O 2 is changed; A graph showing the relationship between the gas pressure and the composition ratio of the Fe—Hf—O film; X-ray diffraction spectra (MT method) of Fe—Hf—O films formed at different gas pressures, X-ray diffraction spectra (FTS method and MT method) of Fe—Hf—O films formed at different gas pressures, The experimental result of the real part μ ′ of the complex relative permeability when the gas pressure and the O ₂ / (Ar + O ₂ ) flow rate ratio are changed when the Fe—Al—O film is formed, When the Fe—Al—O film was formed, the experimental results of the film stress when the gas pressure and the O ₂ / (Ar + O ₂ ) flow rate ratio were changed, X-ray diffraction spectrum of Fe _{73.22 at%} Al _{13.31 at%} O _{13.47 at%} film, X-ray diffraction spectrum of Fe _{83.58 at%} Zr _{8.31 at%} O _{8.11 at%} film,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 RFID device 2 RFID tag 3 and 22 Metal member 4 and 23 Magnetic sheet 5 Resin sheet 6 Magnetic film 7 Amorphous phase 8 Microcrystalline phase 10 Lead dryer 20 Transmitting antenna 21 Receiving antenna

Claims (14)

  On the substrate, A-M-O (where element A represents Fe or Co or a mixture thereof, and element M is Hf, Ti, Zr, V, Nb, Ta, Mo, W, Al, Mg, Zn, Ca) , Ce, and Y), and an amorphous phase containing a compound of elements M and O, and one or two selected from Fe or Co interspersed in the amorphous phase A magnetic sheet formed by physical vapor deposition of a magnetic film formed with a film structure of a microcrystalline phase having an average crystal grain size of 30 nm or less.   The magnetic sheet according to claim 1, wherein the substrate is a flexible resin sheet, and the film structure of the magnetic film is formed without heat treatment. In the magnetic film, the element A is Fe, the composition formula is Fe _a M _b O _c , the composition ratio c of the element O is in the range of 6.85 to 47 at%, and the composition ratio of the element M is 7. 3. The magnetic sheet according to claim 1, wherein the balance is in the range of 95 to 21.38 at%, the balance being the composition ratio a of the element Fe, and satisfying the relationship of a + b + c = 100 at%.   The element M is Hf, the composition ratio c of the element O is in the range of 6.85 to 47 at%, the composition ratio b of the element Hf is in the range of 11.40 to 15.74 at%, and the balance is the composition of the element Fe. The magnetic sheet according to claim 3, wherein the ratio is a and the relationship of a + b + c = 100 at% is satisfied.   The element M is Al, the composition ratio c of the element O is in the range of 699 to 16.75 at%, the composition ratio b of the element Al is in the range of 9.79 to 21.38 at%, and the balance is the element Fe The magnetic sheet according to claim 3, wherein the composition ratio is a and the relationship of a + b + c = 100 at% is satisfied.   The element M is Zr, the composition ratio c of the element O is within the range of 8.11 to 9.29 at%, the composition ratio b of the element Zr is within the range of 7.95 to 8.36 at%, and the balance is the element Fe The magnetic sheet according to claim 3, wherein the composition ratio is a and the relationship of a + b + c = 100 at% is satisfied.   The magnetic sheet according to claim 1, wherein the magnetic sheet is used for an RFID device.   The magnetic sheet according to claim 7, wherein a thickness of the magnetic film is in a range of 0.5 to 15 μm.   The magnetic sheet according to claim 1, wherein the magnetic sheet is used for an electromagnetic wave suppressing body. On the substrate, A-M-O (where element A represents Fe or Co or a mixture thereof, and element M is Hf, Ti, Zr, V, Nb, Ta, Mo, W, Al, Mg, Zn, Ca) , Ce, and Y) are formed by physical vapor deposition, the gas pressure of the mixed gas of inert gas and O ₂ gas is in the range of 0.5 mTorr to 6 mTorr. And an amorphous phase containing a compound of elements M and O, and a microcrystalline phase having an average crystal grain size of 30 nm or less mainly composed of one or two kinds selected from Fe or Co interspersed in the amorphous phase A method for producing a magnetic sheet, comprising forming a film structure. In the magnetic film, the element A is Fe, the composition formula is Fe _a M _b O _c , the composition ratio c of the element O is in the range of 6.85 to 47 at%, and the composition ratio of the element M is 7. The method for producing a magnetic sheet according to claim 10, wherein the magnetic film satisfying the relationship of a + b + c = 100 at% is formed in a range of 95 to 21.38 at%, the balance being the composition ratio a of element Fe.   The element M is Hf, the composition ratio c of the element O is in the range of 6.85 to 47 at%, the composition ratio b of the element Hf is in the range of 11.40 to 15.74 at%, and the balance is the composition of the element Fe. The method of manufacturing a magnetic sheet according to claim 11, wherein the magnetic film satisfying the ratio a and the relationship of a + b + c = 100 at% is formed.   The element M is Al, the composition ratio c of the element O is in the range of 699 to 16.75 at%, the composition ratio b of the element Al is in the range of 9.79 to 21.38 at%, and the balance is the element Fe The method for manufacturing a magnetic sheet according to claim 11, wherein the magnetic film satisfying the relationship of a + b + c = 100 at% is formed.   The element M is Zr, the composition ratio c of the element O is within the range of 8.11 to 9.29 at%, the composition ratio b of the element Zr is within the range of 7.95 to 8.36 at%, and the balance is the element Fe The method for manufacturing a magnetic sheet according to claim 11, wherein the magnetic film satisfying the relationship of a + b + c = 100 at% is formed.

Images