JP2010283333A - Magnetic member for rfid, and rfid device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic member for an RFID, the magnetic member enhancing effectively, in particular, a communication sensitivity, compared with that in the prior art, as to structure for film-forming a magnetic film on a base material by a physical vapor deposition method; and to provide an RFID device. <P>SOLUTION: The magnetic films 7, 8 are laminated to form a plurality of layers while separated by an insulating film 6b, by the physical vapor deposition method, although the magnetic film is film-formed of a single layer on the base material in the prior art. A film thickness in each of the magnetic films 7, 8 is preferably 0.5 μm or more to 3 μm or less. The layer number of magnetic films is within 2-8 of range, in particular, the layer number is preferably 2. The magnetic films 7, 8 are formed, for example, of an Fe-M-O film or an Fe-M-N film, and the insulating films 6a, 6b, 6c are formed, for example, of an SiO<SB>2</SB>film. The communication sensitivity of the RFID device is effectively enhanced compared with that in the prior art, by using the magnetic member for the RFID. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic member for RFID inserted between an RFID tag and a metal member.

  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 member in the vicinity of the RFID tag, an eddy current is generated in the metal by the magnetic field from the reader / writer, and the demagnetizing field due to the eddy current cancels the magnetic field necessary for wireless communication. It was.
JP 2006-81140 A JP 2006-191041 A

  In order to solve the above problem, when a magnetic member is inserted between the metal member and the RFID tag, the magnetic member attracts the magnetic flux from the reader / writer to the RFID tag side, and the reader / writer antenna 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.

  However, for example, an RFID magnetic sheet or ferrite material made of magnetic powder and a binder resin has a sheet thickness of several hundreds of micrometers, and as a result, communication equipment equipped with RFID tags has become thinner. In some cases, an installation space for the magnetic sheet or ferrite material cannot be secured.

  Further, in the RFID magnetic member in which a high-resistance soft magnetic film is formed on a substrate by physical vapor deposition, the magnetic film can be made thinner than the above-described magnetic sheet or ferrite material. The communication sensitivity could not be improved effectively, for example, the communication sensitivity was likely to be equal to or less than that of.

  Patent Document 2 discloses an invention for reducing eddy current loss with a magnetic film having a multilayer structure.

  However, the invention described in Patent Document 2 is not used for RFID, and does not solve the conventional problems in the above-described magnetic member for RFID. In the invention described in Patent Document 2, the specific composition and the like of the magnetic film are unknown, and the film thickness of the magnetic film is a very large film thickness of several hundred μm at the maximum.

  Therefore, the present invention is to solve the above-described conventional problems, and relates to a structure in which a magnetic film is formed on a substrate by a physical vapor deposition method. In particular, the communication sensitivity is effectively improved as compared with the conventional one. It is an object of the present invention to provide an RFID magnetic member and an RFID device that can be made to operate.

  The magnetic member for RFID in the present invention is configured to have a laminated magnetic film and an insulating film interposed between the magnetic films on a base material, and each magnetic film is composed of a main component element T (element T represents Fe or Co or a mixture thereof) and an element M (the element M is at least one of Hf, Ti, Zr, V, Nb, Ta, Mo, W, Al, Mg, Zn, Ca, Ce, and Y). Any one type) and an element X (representing at least one of O or N), the film structure including an element M and a compound of the element X, and the amorphous phase And a microcrystalline phase mainly composed of elements T interspersed therewith.

  The RFID device according to the present invention is characterized in that the RFID magnetic member according to the present invention is interposed between an RFID tag and a metal member.

  According to the present invention, it is possible to effectively improve communication sensitivity as compared with the conventional case where a single-layer structure of a magnetic film is interposed between an RFID tag and a metal member as an RFID magnetic member.

  In the present invention, the thickness of each magnetic film is preferably 0.5 μm or more and 3.0 μm or less. The structure in which the thin magnetic film and the insulating film are stacked in this way can effectively improve communication sensitivity. However, even if the thickness of each magnetic film is made too thin, it is sufficient. Communication sensitivity cannot be improved. Therefore, the lower limit value of the thickness of each magnetic film is set to 0.5 μm.

  By dividing the magnetic film into a plurality of layers as in the present invention and restricting the thickness of each magnetic film as described above, for example, the total thickness of the magnetic film is made equal to the single-layer structure of the conventional magnetic film. Then, compared with the conventional single-layer structure of the magnetic film, the communication sensitivity can be effectively improved, and even if the total thickness is made thinner than the single-layer structure of the conventional magnetic film, it is equivalent to the conventional structure. Adjustments can be made to obtain the above communication sensitivity.

  In the present invention, the total film thickness (total thickness) of the magnetic films is preferably in the range of 1 μm to 12 μm.

  In the present invention, the magnetic film is preferably formed of Fe-MN. By using Fe-MN as the magnetic film in this way, it is possible to obtain the same or higher communication sensitivity as before even if the thickness of each magnetic film and the total thickness of the plurality of magnetic films are made thinner. It is.

In the present invention, the composition ratio of N is preferably 13 at% or more and 18 at% or less. More specifically, it is preferably within a range of 13 at% or more and 16 at% or less. In such a case, it is preferable to form Fe-M-N by an RF conventional sputtering method. Thereby, the real part μ ′ ^{(13.56 MHz)} of the complex relative permeability can be increased to about 2000 or more. Alternatively, the composition ratio of N is preferably in the range of 15 at% or more and 18 at% or less. In such a case, it is preferable to form Fe-MN by DC facing target sputtering. Thereby, the real part μ ′ ^{(13.56 MHz)} of the complex relative permeability can be increased to about 1400 or more.

  In the present invention, the film thickness of each magnetic film made of Fe-MN can be thinly formed to 0.5 μm or more and 1.2 μm or less. According to the experiment described later, it is found that even if the thickness of each magnetic film is 1 μm or less and the total thickness of the plurality of magnetic films is reduced, a high communication output can be obtained and the communication distance can be effectively extended. It was.

  Alternatively, in the present invention, the magnetic film is preferably formed of Fe-MO. In such a case, the thickness of each magnetic film is preferably 0.7 μm or more and 2.8 μm or less.

  In the present invention, the number of laminated magnetic films is preferably in the range of 2-8. In particular, the number of laminated magnetic films is more preferably 2. Thereby, the total thickness of the magnetic film can be reduced and the communication sensitivity can be effectively improved.

In the present invention, the insulating film is preferably a SiO ₂ film.
In the present invention, the magnetic film can be formed on the substrate directly or via an insulating film. That is, it can be formed by base material / magnetic film / insulating film / magnetic film..., Base material / insulating film / magnetic film / insulating film / magnetic film.

  Moreover, in this invention, it is preferable that the said base material is a flexible resin sheet, and the film | membrane structure of the said magnetic film is formed without heat-processing. Accordingly, 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.

  Moreover, in this invention, the said base material may be formed with the metal. That is, metal / insulating film / magnetic film / insulating film / magnetic film..., Metal / magnetic film / insulating film / magnetic film.

  In the RFID device according to the present invention, a magnetic film may be formed between the RFID tag and the metal member using the metal member as a base material.

  According to the present invention, it is possible to effectively improve the communication sensitivity as compared with the prior art.

Schematic diagram of RFID device and reader / writer, The fragmentary sectional view of the magnetic member of the embodiment of the present invention, Schematic diagram of the film structure of the Fe-MO film, The fragmentary sectional view of the magnetic member of the embodiment of the present invention different from FIG. A graph showing the relationship between the thickness of the magnetic film of each magnetic member used in the experiment (total thickness when there are multiple magnetic films) and the signal strength of the RFID device at 13.56 MHz; A graph showing the relationship between frequency and signal output in Example 1 using a laminated film of FeAlN (deposited by RF conventional sputtering method) and Comparative Examples 1 to 5, A graph showing the relationship between the frequency in the magnetic member of Example 1 and the real part μ ′ and the imaginary part μ ″ of the complex relative permeability, A graph showing the relationship between frequency and signal output in Example 2 using a laminated film of FeAlN (deposited by a DC facing target sputtering method) and Comparative Examples 1 and 2, A graph showing the relationship between the frequency in the magnetic member of Example 2 and the real part μ ′ and the imaginary part μ ″ of the complex relative permeability, The graph which shows the relationship between the film thickness of each magnetic film, and the maximum communication distance.

  FIG. 1 is a schematic diagram of an RFID device and a reader / writer, FIG. 2 is a partial cross-sectional view of a magnetic member for RFID according to an embodiment of the present invention (partial cross-sectional view taken along the film thickness direction), and FIG. It is a schematic diagram of the film | membrane structure of the magnetic film of embodiment.

  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 an RFID magnet interposed between the RFID tag 2 and the metal member 3. And a member 4. RFID is known as a communication system using electromagnetic induction at 13.56 MHz.

  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 thickness of about 0.05 to 0.5 mm.

  As shown in FIG. 1, by inserting the RFID magnetic member 4 between the RFID tag 2 and the metal member 3, the magnetic flux B from the reader / writer 11 passes through the RFID magnetic member 4, and the RFID device 1 A reflux magnetic flux is formed with the reader / writer 11. As a result, the attenuation of the signal output received by the antenna of the RFID tag 2 can be reduced, and the communication sensitivity at 13.56 MHz can be effectively improved.

  The RFID magnetic member 4 inserted between the RFID tag 2 and the metal member 3 has insulating films 6a, 6b and 6c and magnetic films 7 and 8 alternately on a substrate 5 as shown in FIG. It is a laminated form. The magnetic films 7 and 8 and the insulating films 6a, 6b, and 6c are preferably formed by physical vapor deposition.

  The magnetic films 7 and 8 are TMX (where T 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 represents at least one of them, and the element X represents at least one of O or N).

  The magnetic films 7 and 8 are not only formed on the entire surface of the base material 5 but also partially formed, for example, only on the central portion of the base material 5 while leaving the edge of the base material 5. Also good. However, when the RFID magnetic member 4 and the RFID tag 2 are stacked as shown in FIG. 1, the magnetic films 7 and 8 are preferably formed to have a size that completely faces the entire surface of the RFID tag 2. It is.

  The magnetic films 7 and 8 are formed without being subjected to heat treatment during film formation or after film formation. Thus, even in non-heat treatment, as shown in FIG. It includes a mixed phase structure having an amorphous phase 9 and a microcrystalline phase 10 mainly composed of elements T interspersed in the amorphous phase 9. The average particle diameter of the microcrystalline phase 10 can be 30 nm or less.

The magnetic films 7 and 8 of this embodiment are high resistance soft magnetic films and are excellent in soft magnetic characteristics. For example, the real part μ ′ ^{(13.56 MHz)} of the complex relative magnetic permeability can be 200 or more, preferably 300 or more, preferably 800 or more, more preferably 1400 or more, still more preferably 2000 or more, and the specific resistance ρ can be 100 ( μΩ · cm) or more, preferably 150 (μΩ · cm) or more, more preferably 200 (μΩ · cm) or more, and even more preferably 300 (μΩ · cm) or more.

The magnetic films 7 and 8 of this embodiment are preferably formed of Fe-MN, and the composition ratio of N at that time is preferably 13 at% or more and 18 at% or less. More specifically, the composition ratio of N is preferably in the range of 13 at% to 16 at%. The composition ratio (at%) of the remaining Fe and M is preferably adjusted so that [M / (Fe + M)] × 100 (%) falls within the range of 16 to 20%. In such a case, it is preferable to form Fe-M-N by an RF conventional sputtering method. Thereby, the real part μ ′ ^{(13.56 MHz)} of the complex relative permeability can be increased to about 2000 or more.

Alternatively, the composition ratio of N is preferably in the range of 15 at% or more and 18 at% or less. The composition ratio (at%) of the remaining Fe and M is preferably adjusted so that [M / (Fe + M)] × 100 (%) falls within the range of 17 to 19%. In such a case, it is preferable to form Fe-MN by DC facing target sputtering. Thereby, the real part μ ′ ^{(13.56 MHz)} of the complex relative permeability can be increased to about 1400 or more.

Or, the magnetic film 7 and 8 of this embodiment, the composition formula is represented by T _a M _b X _c, the element T to Fe, the element X can be selected to O. At this time, the element M is Zr, the composition ratio b of Zr is in the range of 7.95 to 8.36 at%, and the composition ratio c of O is in the range of 8.11 to 9.27 at%. Is preferred. The sum of the composition ratios a + b + c is 100 at%.

Alternatively, in the magnetic films 7 and 8 of the present embodiment, the composition formula is represented by T _a M _b X _c , the element T is Fe, the element M is Al, the element X is O, and the Al composition ratio b Is preferably in the range of 9.79 to 21.38 at%, and the composition ratio c of O is preferably in the range of 699 to 16.75 at%. The sum of the composition ratios a + b + c is 100 at%.

In the magnetic film made of Fe-M-O, the real part μ ′ ^{(13.56 MHz) of the} complex relative permeability is likely to be smaller than that of the magnetic film made of Fe-MN, but by adjusting the composition ratio as described above It is possible to obtain a real part μ ′ ^{(13.56 MHz)} having a complex relative permeability of about 800 or more, preferably about 1000 or more.

  The film structure of the magnetic films 7 and 8 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 9 in the magnetic films 7 and 8 is present not only at the grain boundary between the microcrystalline phases 10 but also surrounding the periphery. As described above, the magnetic films 7 and 8 have a mixed phase structure in which the microcrystalline phases 10 are scattered in the amorphous phase 9.

  The amorphous phase 9 contained in the magnetic films 7 and 8 is preferably about 20 to 80% by volume.

  The insulating films 6a, 6b, and 6c stacked alternately with the magnetic films 7 and 8 are films that electrically insulate the magnetic films 7 and 8 from each other. In this embodiment, it is necessary to have an insulating film 6b interposed between at least the magnetic films 7 and 8. Further, as shown in FIG. 2, it is preferable to provide insulating films above and below the magnetic films 7 and 8, respectively. The lowermost insulating film 6a shown in FIG. 2 functions as a base film, and the uppermost insulating film 6c functions as a protective film against external factors such as environmental changes.

  Alternatively, as shown in FIG. 4, the magnetic film 7 may be formed directly on the substrate 5. In this case, the number of insulating layers can be reduced, the thickness of the entire RFID magnetic member 4 can be reduced, and the production cost can be reduced.

As the insulating films 6a, 6b, and 6c, an oxide insulating film, a nitride insulating film, a carbonized insulating film, and the like can be presented, but an oxide insulating film is preferable. Further, one or more of SiO ₂ film, Al ₂ O ₃ film, Fe ₂ O ₃ film, Ta ₂ O ₃ film, TiO ₂ film, and Mo ₂ O ₃ film can be selected for the insulating films 6a, 6b, and 6c. . The insulating films 6a, 6b and 6c are the same TMO films as the magnetic films 7 and 8, but have a high O composition ratio (specifically, 30 at% or more) and insulating TMO. It can also be a film. In this case, there is an advantage that the same target can be used for forming the insulating films 6a, 6b, and 6c and forming the magnetic films 7 and 8. This T-M-O film is a non-magnetic film consisting entirely of an oxide crystal phase or an amorphous phase and an oxide crystal phase, and is different from the crystal structure of the magnetic films 5, 7, and 8. is there.

  In the present embodiment, as shown in FIG. 2, the thickness of each of the magnetic films 7 and 8 is T1. Here, the magnetic films 7 and 8 can have the same film thickness or different film thicknesses. The film thickness of each of the magnetic films 7 and 8 is preferably 0.5 μm or more and 3 μm or less.

  When the magnetic films 7 and 8 in this embodiment are formed of Fe-MN, the thickness of each magnetic film 7 and 8 can be set to 0.5 μm or more and 1.2 μm or less. Thus, even when the thickness of each magnetic film is 1.2 μm or less and the total thickness of the plurality of magnetic films is reduced, a high communication output can be obtained and the communication distance can be effectively extended.

  Moreover, when the magnetic films 7 and 8 in this embodiment are formed by Fe-MO, the film thickness of each magnetic film 7 and 8 can be 0.7 micrometer or more and 2.8 micrometers or less. Further, it is more preferable that the thickness of each of the magnetic films 7 and 8 is 1.5 μm or more and 2.8 μm or less. Thereby, a high communication output can be obtained and the communication distance can be effectively extended.

By forming the magnetic films 7 and 8 with Fe-MN having a high real part μ ′ ^{(13.56 MHz)} of the complex relative permeability, the thicknesses of the magnetic films 7 and 8 and Even if the total thickness of the plurality of magnetic films 7 and 8 is reduced, a high communication output can be obtained and the communication distance can be effectively extended.

  However, even if the magnetic films 7 and 8 (regardless of Fe-MO, Fe-MN) are made too thin, it is not possible to sufficiently improve the communication sensitivity. Therefore, the lower limit value of the thickness of each magnetic film is set to 0.5 μm.

  Conventionally, a magnetic film is formed as a single layer on a base material, but in this embodiment, the magnetic films 7 and 8 are divided into a plurality of layers via an insulating film and laminated. At that time, as described above, by restricting the film thickness T1 of each of the magnetic films 7 and 8 within a predetermined range, for example, the total of the magnetic films 7 and 8 is caused by factors such as reduction of eddy current loss of each magnetic film. When the thickness is equivalent to that of the conventional single layer structure of the magnetic film, the communication sensitivity of the RFID device 1 of FIG. 1 can be effectively improved as compared with the single layer structure of the conventional magnetic film. Even if the total thickness is made thinner than the conventional single-layer structure of the magnetic film, it can be adjusted so that the communication sensitivity equal to or higher than the conventional one can be obtained.

  In the present embodiment, the number of stacked magnetic films 7 and 8 can be set to about 2 to 8, and the number of stacked layers can be set to about 2 to 4 in accordance with the condition of the film thickness T1 of the magnetic films 7 and 8 described above. It is preferable that the number of layers is two, and it is more preferable. In the present embodiment, the magnetic films are not extremely subdivided, and the magnetic films 7 and 8 are formed with a certain thickness as described above (specifically 0.5 μm or more), and the number of stacked layers is small. As a result, the total thickness of the magnetic films 7 and 8 can be reduced, and the communication sensitivity can be effectively improved.

  The total thickness T1 of the magnetic films 7 and 8 is preferably 1 μm or more and 12 μm or less. Further, the total thickness can be 8 μm or less, or 6 μm or less. Further, when Fe-MN is used for the magnetic films 7 and 8, the total thickness can be set to 2.4 μm or less. The total thickness can be calculated from the film thickness T1 of each magnetic film 7 and 8 and the number of stacked layers. In the present embodiment, the total thickness of the magnetic films 7 and 8 can be made thinner than that of the conventional single-layer structure of the magnetic film. In such a case, communication sensitivity equal to or higher than that of the conventional one can be obtained.

  The thickness of each insulating film 6a, 6b, 6c is preferably about 10 nm to 500 nm, and more preferably 100 nm or less.

  In the RFID device 1 illustrated in FIG. 1, a flexible resin sheet, a glass substrate, or the like can be used as the base material 5 illustrated in FIGS. 2 and 4. At this time, if a resin sheet is used as the base material 5, the RFID magnetic member 4 can be appropriately curved even when the RFID magnetic member 4 is curved, and the magnetic films 7 and 8 include the amorphous phase 9. Even when the magnetic films 7 and 8 are deformed from the planar shape together with the base material 5 which is a resin sheet, the magnetic films 7 and 8 are not easily damaged such as cracks.

  In addition, since the magnetic films 7 and 8 are not subjected to heat treatment, the material of the base material 5 that supports the magnetic films 7 and 8 may not be particularly limited. That is, the selectivity of the material of the base material 5 can be expanded. Further, since there is no thermal influence on the base material 5, it is possible to obtain the dimensional stability of the RFID magnetic member 4 with higher accuracy than before. For the base material 5, a thermoplastic resin can be used. Among them, PEN (polyethylene naphthalate) and PPS (polyphenylene sulfide), which are excellent in heat resistance, are suitable, but PET (polyethylene terephthalate) and amylado (all Aromatic polyamide), polyimide, glass epoxy (FR4) and the like can also be used. Alternatively, a sheet coated with a protective insulating layer such as a resist may be used.

In the present embodiment, the thickness of the substrate 5 can be set to about 10 to 100 μm.
Further, when the RFID magnetic member 4 shown in FIG. 2 is inserted between the metal member 3 and the RFID tag 2 in FIG. 1, the RFID magnetic member 4 is inserted so that the base material 5 faces the metal member 3 side. Even if it inserts so that the said base material 5 may oppose the RFID tag 2 side, either may be sufficient. 1, there are adhesive layers between the RFID tag 2 and the RFID magnetic member 4 and between the RFID magnetic member 4 and the metal member 3. As shown in FIG. The RFID magnetic member 4 may be directly formed on the surface of the RFID tag 2.

  Alternatively, the substrate 5 may be made of metal. That is, in the form of FIG. 2, the base material 5 / insulating film 6a / magnetic film 7 / insulating film 6b / magnetic film 8 / insulating film 6c formed of metal can be used. In the form shown in FIG. If present, the base material 5 / magnetic film 7 / insulating film 6b / magnetic film 8 / insulating film 6c formed of metal can be used.

Further, the base member 5 may be the metal member 3 shown in FIG. That is, the RFID device 1 can be metal member 3 / insulating film 6a / magnetic film 7 / insulating film 6b / magnetic film 8 / insulating film 6c / adhesive layer / RFID tag 2, or metal member 3 / magnetic. Film 7 / insulating film 6b / magnetic film 8 / insulating film 6c / adhesive layer / RFID tag 2 can be used. As a result, the RFID device 1 can be formed more effectively and the production cost can be reduced. In either case of FIGS. 1 and 2, it is preferable to form a protective film such as SiO _{2 on} the outermost surface of the laminate.

  The magnetic films 7 and 8 and the insulating films 6a, 6b, and 6c of this embodiment are formed by physical vapor deposition. As physical vapor deposition, RF or DC parallel plate magnetron sputtering (MT method), DC facing Target sputtering method (FTS method), RF facing target sputtering method, RF conventional sputtering method, vapor deposition method, reactive plasma vapor deposition method and the like can be presented.

(Experiment using magnetic member with FeZrO single layer structure)
A conventional magnetic member in which a FeZrO single layer structure was formed on a substrate was produced. A borosilicate glass substrate was used as the substrate. The thickness of the glass substrate was 0.55 mm.

Then, an FeZrO film was formed by sputtering on the borosilicate glass substrate. An Fe—Zr 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 was 63 sccm, the Ar + 5% O ₂ gas flow rate was 12 sccm, the RF power was 600 W, the gas pressure was 3 mTorr, and the substrate was not indirectly cooled.
The FeZrO film used in the experiment was Fe _{83.58 at%} Zr _{8.31 at%} O _{8.11 at%} .

  The magnetic member produced as described above is inserted between the receiving antenna and the metal plate, and the output value of the received signal from the receiving antenna at 13.56 MHz is measured using a spectrum analyzer (Anritsu Co., Ltd., model: MS2601B). (Measurement of communication strength). The communication distance between the transmitting antenna and the receiving antenna was 28 mm. The transmitting antenna and the receiving antenna were formed on a substrate having a plane size of 55 mm × 85 mm and a thickness of 0.55 mm. Further, the transmitting antenna and the receiving antenna were formed in a planar pattern having a maximum outer edge dimension of 30 mm × 30 mm and 3 turns.

  Further, the metal plate was formed of Al having a plane size of 55 mm × 85 mm and a thickness of 2 mm.

The experiment was performed using a plurality of magnetic members having different thicknesses of the FeZrO single layer film.
In addition, when the magnetic member is interposed between the receiving antenna and the metal plate, the magnetic member base is opposed to the metal plate, and the magnetic member is opposed to the receiving antenna. Experiments were conducted for both cases.

(Experiment of magnetic member having laminated structure of SiO ₂ / FeZrO ...)
The base material, FeZrO sputtering conditions, composition ratio, and communication strength measurement conditions are the same as described above.

A SiO ₂ film was formed using a SiO ₂ 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 was 75 sccm, the RF power was 300 W, the gas pressure was 3 mTorr, and the substrate was not indirectly cooled. The thickness of each SiO ₂ film was unified to 0.1 μm.

The SiO ₂ film was provided not only between the FeZrO films but also on the surface of the uppermost FeZrO film as shown in FIG.

  In the experiment, when the film thickness of the FeZrO film was 0.25 μm, the number of layers of the FeZrO film was 4 and 12, and when the film thickness of the FeZrO film was 0.5 μm, the number of layers of the FeZrO film was 6, 7 and 8, and the thickness of the FeZrO film was 2.8 μm, the number of FeZrO films was 3 and 4.

  In the experiment, the number of stacked FeZrO films was 2, and the thickness of the FeZrO film at that time was 0.7 μm, 1 μm, 1.5 μm, and 2.8 μm.

  In addition, when the magnetic member is interposed between the receiving antenna and the metal plate, the magnetic member base is opposed to the metal plate, and the magnetic member is opposed to the receiving antenna. Experiments were conducted for both cases.

  FIG. 5 shows the experimental results of communication strength. The communication intensity in FIG. 5 means that the smaller the absolute value, the better the communication sensitivity. FIG. 5 also shows a configuration in which a metal plate and a magnetic member are not provided (“no metal” shown in FIG. 5) or a configuration of a receiving antenna / base material / metal plate (“base material / metal (shown in FIG. 5)”. The experimental results of the communication strength for “no magnetic member)”) are also shown. In addition, the plots of “magnetic film / base material / no metal insulation film” and “base material / magnetic film / no metal insulation film” shown in FIG. 5 are the experimental results of the communication strength in the above-described conventional example.

The horizontal axis shown in FIG. 5 is the total thickness of each FeZrO film in a magnetic member in which a SiO ₂ film is interposed between a plurality of FeZrO films.

  Further, in the experimental results of the magnetic member in which the number of stacked FeZrO films is 2, the film thickness of each FeZrO film is shown on the graph.

As shown in FIG. 5, among the magnetic members in which the SiO ₂ film is interposed between the plurality of FeZrO films, the communication strength of the magnetic member in which the thickness of each FeZrO film is 0.5 μm is the same as that of the FeZrO film. It was found that the communication sensitivity can be improved as compared with the conventional one by setting the layer thickness of each FeZrO film to 0.5 μm or more, slightly above the communication intensity line in the conventional example having a layer structure.

Also, as shown in FIG. 5, among the magnetic members in which the SiO ₂ film is interposed between the plurality of FeZrO films, if the thickness of each FeZrO film is 0.7 μm or more, the total thickness of each FeZrO film is It was found that the communication sensitivity can be improved more effectively when compared with the case where the film thickness is equivalent to that of the single layer structure of the FeZrO film. From this experimental result, the range in which the film thickness of each FeZrO film was 0.7 μm or more and 2.8 μm or less was set as a preferable range. Further, the range in which the film thickness of each FeZrO film was 1.5 μm or more and 2.8 μm or less was further preferred.

  Further, the number of stacked FeZrO films should be about 2 to 8, preferably 2 to 4. Particularly, by setting the number of stacked layers to 2, it is possible to reduce the total thickness of the magnetic film and obtain excellent communication sensitivity. I knew it was possible.

  As shown in FIG. 5, for example, when the thickness of each of the two magnetic films is 2.8 μm and the total thickness is 5.6 μm, the thickness of the magnetic film having a single-layer structure is 5.6 μm. Compared to the above, or it was found that the communication sensitivity can be sufficiently increased even for the conventional example in which the thickness of the magnetic film having a single layer structure is thicker than 5.6 μm.

(Experiment of a magnetic member having a laminated structure of FeAlN / SiO ₂ / FeAlN)
In the experiment, FeAlN (0.9) / SiO ₂ (0.1) / FeAlN (0.9) was formed on the SUS substrate by RF conventional sputtering. The numerical values in parentheses indicate the film thickness and the unit is μm.

As the sputtering apparatus, SPF-730 manufactured by Canon Anelva was used. The FeAlN film used in the experiment was Fe _{69.75 at%} Al _{16.04 at%} N _{14.21 at%} .

  Regarding the relationship between the frequency and signal output, the magnetic film produced as described above is placed between the receiving antenna (tag) and the SUS substrate (SUS304) that is the base material for forming the magnetic film. Examined. The frequency and signal output were measured using a network analyzer (manufactured by Agilent). The communication distance between the transmitting antenna and the receiving antenna was 15 mm.

  Further, Comparative Example 1 in which no magnetic member is inserted between the receiving antenna (tag) and the metal plate (SUS304), and the magnetic field for RFID manufactured by Alps Electric Co., Ltd. between the receiving antenna (tag) and the metal plate (SUS304). Comparative Example 2 in which a sheet (80R50) is inserted, Comparative Example 3 in which a single-layer FeAlN film having a thickness of 1 μm is interposed between a receiving antenna (tag) and a metal plate (SUS304), a receiving antenna (tag) and a metal Comparative Example 4 in which a single-layer FeAlN film having a thickness of 2 μm is interposed between the plates (SUS304), and a single-layer FeAlN film having a thickness of 3 μm between the receiving antenna (tag) and the metal plate (SUS304). A similar experiment was conducted for Comparative Example 5 in which the interposed magnetic member was inserted.

  The experimental results are shown in FIG. The signal output shown in FIG. 6 indicates that the larger the absolute value, the better the communication sensitivity. As shown in FIG. 6, in Comparative Examples 3 to 5 using a single-layer FeAlN film, the signal output increases as the film thickness of the FeAlN film increases, and the resonance frequency can also approach 13.56 MHz. It was found that the signal output (absolute value) was smaller than that of Example 2 and a sufficient communication distance could not be obtained.

  In Comparative Example 2, the resonance frequency is approximately 13.56 MHz and the signal output (absolute value) can be increased. Comparative example 2 is an index for this example. In Comparative Example 2, a magnetic film including a binder resin and magnetic powder is formed into a sheet, and the film thickness is about 50 μm to 200 μm. The present embodiment aims to further reduce the film thickness while having RFID characteristics equivalent to those of Comparative Example 2.

Example 1 used in the experiment has a laminated structure of FeAlN / SiO ₂ / FeAlN. Each FeAlN film is very thin with a thickness of 0.9 μm, and the total thickness is 1.8 μm even when the two layers of FeAlN are combined. Although the film thickness is much thinner than that of the comparative example 2, even if the total thickness of the magnetic film is formed as described above, the signal output (absolute value) substantially equal to that of the comparative example 2 is obtained in the example 1. I knew I could do it.

  Further, in the case of the FeZrO film used in the experiment of FIG. 5, a good experimental result with the two-layer structure is a case where each FeZrO film is formed with a film thickness of 2.8 μm, and the total thickness is 5.6 μm. . Thus, in Example 1 formed with the FeAlN film, the total thickness of the magnetic film can be made thinner than when the FeZrO film is used, and the signal output (absolute value) is almost equivalent to that of Comparative Example 2 shown in FIG. I found out I could get

  The relationship between the frequency and the real part μ ′ and imaginary part μ ″ of the complex relative permeability was measured using the magnetic member of Example 1 used in the experiment of FIG. 6. The real part μ ′ of the complex relative permeability and The imaginary part μ ″ was measured using a network analyzer (manufactured by Agilent). The experimental results are shown in FIG.

  As shown in FIG. 7, it was found that the real part μ ′ of the complex relative permeability can be made about 2000 at a frequency of 13.56 MHz.

Next, in the experiment, FeAlN (0.9) / SiO ₂ (0.1) / FeAlN (0.9) was formed on a SUS substrate by a DC facing target sputtering method. The numerical values in parentheses indicate the film thickness and the unit is μm.
The FeAlN film used in the experiment was Fe _{67.62 at%} Al _{15.04 at%} N _{17.34 at%} .

  Experiments similar to those shown in FIGS. 6 and 7 were performed. FIG. 8 shows the experimental results of Comparative Example 1 and Comparative Example 2 also shown in FIG. Example 2 shown in FIG. 8 is an experimental result using a magnetic member in which the above-described FeAlN film is formed by a DC facing target sputtering method.

  As shown in FIG. 8, when Example 2 in which the total thickness of the magnetic film is very thin (total thickness is 1.8 μm) is used, a resonance frequency and a signal output (absolute value) substantially equivalent to those in Comparative Example 2 are obtained. I knew I could do it.

  FIG. 9 shows the relationship between the frequency and the real part μ ′ and the imaginary part μ ″ of the complex relative permeability in the magnetic member of Example 2. As shown in FIG. 9, the complex ratio at a frequency of 13.56 MHz. It was found that the real part μ ′ of the permeability could be about 1800.

(Maximum communication distance experiment)
Subsequently, the maximum communication distance in Comparative Examples 1 to 5, Example 1 and Example 2 in FIG. 6 was measured. The maximum communication distance was defined as the “maximum communication distance” when the transmission antenna and the reception antenna were gradually separated and communication was impossible.

The communication distance was measured using TAKAYA-TR3 manufactured by Takaya Corporation. The tag used was RI-I02-112B-03 (55 × 85 size) manufactured by TI.
The experimental results are shown in Table 1 below.

  As shown in Table 1, it was found that Examples 1 and 2 can obtain a maximum communication distance substantially equal to that of Comparative Example 2.

(Experiment regarding the relationship between magnetic film thickness and communication distance)
On a SUS substrate, FeAlN (X) / SiO ₂ (0.1) / FeAlN (X) (X = 0.6, 0.7, 0.8, 0.9, 1.0, 1.2 μm) The film was formed by RF conventional sputtering. The FeAlN film used in the experiment was Fe _{69.75 at%} Al _{16.04 at%} N _{14.21 at%} . These samples were measured for the maximum communication distance at each film thickness X in the same manner as in Table 1. The measurement results are shown in FIG. In addition, the plot of Example 2 and the line of the value of the maximum communication distance of the comparative example 2 were also published in FIG.

  As shown in FIG. 10, it is found that the maximum communication distance is increased when the value of the film thickness X of each magnetic film is 0.6 μm or more and 1.2 μm or less, more preferably 0.7 μm or more and 1.0 μm or less. It was.

(Experiment regarding the relationship between the film composition of the magnetic film and the real part μ ′ of the complex relative permeability)
An FeZrO (0.2 μm) magnetic film was formed on each substrate by RF magnetron sputtering, and the composition ratio of each FeZrO formed on each substrate was shown in Table 2 below. Films were formed at the indicated values.

  Next, a FeAlN (0.2 μm) magnetic film is formed on each substrate by RF conventional sputtering, and at this time, the composition ratio of each FeAlN formed on each substrate is as follows. Films were formed at the values shown in Table 2.

  Next, a FeAlN (0.2 μm) magnetic film is formed on each substrate by a DC facing target sputtering method. At this time, the composition ratio of each FeAlN formed on each substrate is as follows. Films were formed at the values shown in Table 2.

  The composition ratio of each magnetic film was measured by EDS (energy dispersive X-ray fluorescence spectroscopy) or AES (Auger electron spectroscopy).

As shown in Table 2, when an FeMO film is used as the magnetic film, the real part μ ′ ^{(13.56 MHz)} of the complex relative permeability is 800 or more when the composition ratio of O is in the range of 8.11 to 9.27 at%. It was found that it can be preferably 1000 or more. It was also found that the imaginary part μ ″ ^{(13.56 MHz)} of the complex relative permeability can be reduced to about 50 to 70. Further, the composition ratio of Fe and M is [M / (Fe + M)] × 100 (%). It turned out that it is suitable to adjust so that it may exist in the range of 8.8-9.1%.

Next, when the FeMN film formed by the RF conventional sputtering method is used, assuming that the composition ratio of N is in the range of 13 at% to 16 at%, the real part μ ′ ^(13.56) of the complex relative permeability. ^(MHz) can be increased to about 2000 or more. It was also found that the imaginary part μ ″ ^{(13.56 MHz)} of the complex relative magnetic permeability can be reduced to about 100 to 300. Further, the composition ratio (at%) of the remaining Fe and M is [M / (Fe + M)]. It turned out that it is suitable to adjust so that x100 (%) may exist in the range of 16-20%.

Next, when the FeMN film formed by the DC facing target sputtering method is used, if the N composition ratio is in the range of 15 at% to 18 at%, the real part μ ′ ⁽ It was found that ^{13.56 MHz)} can be increased to about 1400 or more. It was also found that the imaginary part μ ″ ^{(13.56 MHz)} of the complex relative permeability can be reduced to about 100 to 200. Further, the composition ratio (at%) of the remaining Fe and M is [M / (Fe + M)]. × 100 (%) was found to be preferably adjusted to be in the range of 17 to 19%, and when the composition ratio of N was about 15 at% to 17.4 at%, the complex relative permeability It was found that the real part μ ′ ^{(13.56 MHz)} can be increased to about 1700 or more, which is more preferable.

DESCRIPTION OF SYMBOLS 1 RFID device 2 RFID tag 3 Metal member 4 RFID magnetic member 5 Base material 6a, 6b, 6c Insulating film 7, 8 Magnetic film 9 Amorphous phase 10 Microcrystalline phase 11 Reader / writer

Claims (16)

  Each of the magnetic films is composed of a main component element T (element T is Fe or Co or a mixture thereof). Element), element M (element M represents at least one of Hf, Ti, Zr, V, Nb, Ta, Mo, W, Al, Mg, Zn, Ca, Ce, and Y), and element X (represents at least one of O and N), and the film structure is mainly composed of an amorphous phase containing a compound of the element M and the element X, and the elements T scattered in the amorphous phase. A magnetic member for RFID, comprising a microcrystalline phase.   The magnetic member for RFID according to claim 2, wherein the thickness of each magnetic film is 0.5 μm or more and 3 μm or less.   The magnetic member for RFID according to claim 2, wherein the total film thickness of each magnetic film is in a range of 1 μm to 12 μm.   The magnetic member for RFID according to any one of claims 1 to 3, wherein the magnetic film is formed of Fe-MN.   5. The magnetic member for RFID according to claim 4, wherein the composition ratio of N is in the range of 13 at% or more and 18 at% or less.   6. The RFID magnetic member according to claim 4, wherein the thickness of each magnetic film is 0.5 μm or more and 1.2 μm or less.   The magnetic member for RFID according to any one of claims 1 to 3, wherein the magnetic film is formed of Fe-MO.   8. The magnetic member for RFID according to claim 7, wherein the thickness of each magnetic film is 0.7 μm or more and 2.8 μm or less.   The magnetic member for RFID according to claim 2, wherein the number of laminated magnetic films is in a range of 2 to 8.   The RFID magnetic member according to claim 9, wherein the number of laminated magnetic films is two. The RFID magnetic member according to claim 1, wherein the insulating film is a SiO ₂ film.   The magnetic member for RFID according to claim 1, wherein the magnetic film is formed directly on the base material or via an insulating film.   The RFID magnetic member according to claim 1, wherein the base material is a flexible resin sheet, and the magnetic film is formed without heat treatment.   14. The RFID magnetic member according to claim 1, wherein the substrate is made of metal.   An RFID device comprising the RFID magnetic member according to any one of claims 1 to 14 interposed between an RFID tag and a metal member.   15. An RFID device, wherein the magnetic film according to claim 14 is formed between the RFID tag and a metal member using the metal member as a base material.

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