Anisotropic electroconductive film, electroconductive connector, and electroconductive structure used therefor

Abstract

Provided are an anisotropic electroconductive film and an electroconductive connector that are capable of achieving lower resistance, higher frequency characteristics, higher resolution, higher contact stability resulting from reduction of contact pressure, higher current, and higher durability than in the past.　An anisotropic electroconductive film 110 includes: an insulating thin film 112 made of a polymer material having elasticity; and particles 200 that are dispersed in the insulating thin film 112 and are imparted with magnetic anisotropy so that the easy magnetization direction of the particles 200 is in the thickness direction of the insulating thin film 112, the particles 200 being made of a substance exhibiting topological antiferromagnetic characteristics. The particles 200 are arranged apart from each other in the in-plane direction of the insulating thin film 100, the particles 200 forming a plurality of conduction parts 114 capable of conducting in the thickness direction. Each conduction part 114 is formed from a single particle 200 (or a plurality of particles 200 arranged in the thickness direction). Each of the particles 200 has a south-pole region 604 and a north-pole region 602 formed at two ends in a direction following the easy magnetization direction. The magnetic flux of a virtual magnetic field is concentrated at the south-pole region 604 and the north-pole region 602.

Description

Anisotropic conductive film, conductive connector, and conductive structure used therein

[0001] The present invention relates to an anisotropic conductive film and a conductive connector, as well as a conductive structure used therein; more particularly, to a conductive connector having a configuration in which a conductive part made of a substance exhibiting topological antiferromagnetic properties is disposed in an insulating thin film made of an insulating polymer material, and which has a configuration in which an anisotropic conductive film exhibits anisotropic conductivity in the thickness direction and a movable electrode is combined with the anisotropic conductive film, and to a conductive structure that is suitably used as the conductive part disposed in the anisotropic conductive film and the conductive connector.

[0002] In the manufacturing process of integrated circuits (ICs), after forming desired circuits on silicon wafers (hereinafter simply referred to as wafers), wafer tests are performed to verify whether the circuits function properly. These wafer tests are performed using semiconductor testing equipment. Specifically, the semiconductor testing equipment inspects the electrical characteristics of the circuits by contacting probes attached to a test head with the wafer and transmitting and receiving electrical signals between the semiconductor testing equipment connected to the test head and the circuits formed on the wafer.

[0003] Typically, hundreds of ICs are formed on a silicon wafer, and wafer testing involves testing these ICs collectively or separately before they are separated. If the IC is a memory such as RAM or ROM, the number of electrodes per IC is in the tens to hundreds, but if the IC is a CPU, GPU, MPU, etc., the number of electrodes per IC can be in the hundreds to tens of thousands. Therefore, when testing multiple ICs simultaneously, it is necessary to connect probes to tens of thousands or more of electrodes at once.

[0004] In recent years, in addition to metal probes, probes using anisotropic conductive films (so-called conductive rubber) have also come into use as probes for semiconductor testing equipment. This is because probes using anisotropic conductive films are less susceptible to damage due to deformation of the test electrodes than metal probes, and are also advantageous for miniaturizing the test electrode spacing. However, because the fragility of anisotropic conductive films has become an issue with miniaturization, their use has been limited to package probes designed for testing ICs after separation and packaging. In other words, practical application of anisotropic conductive films in wafer probes designed for testing ICs before separation has not yet been realized.

[0005] Prior to this application, the applicant developed an anisotropic conductive film, filed a patent application, and has already been granted a patent (see Patent Document 1). The anisotropic conductive film disclosed in Patent Document 1 (Japanese Patent No. 5755527) is a sheet-like anisotropic conductive film having anisotropic conductivity in the thickness direction, in which conductive particles are dispersed in an elastic insulating polymeric material. The particle size d10 of the conductive particles at the cumulative 10% of the particle size distribution is less than half the particle size d90 at the cumulative 90% of the particle size distribution, and the particle shape d90 of the conductive particles is 70% to 90% of the average thickness of the elastic insulating polymeric material. Thus, the particle size d90 of the conductive particles in the particle size cumulative distribution is 70% to 90% of the average thickness of the elastic insulating polymeric material, i.e., approximately 80%, which means the following:

[0006] In other words, this means that the electrodes of the electrode substrate of the test head on one side of the anisotropic conductive film and the terminals (electrodes) of the circuit on the wafer on the other side of the anisotropic conductive film are electrically connected via the individual (single) conductive particles of the particle size d90 (large diameter) when the test head is pressed against the wafer, and further means that the individual (single) conductive particles of the particle size d90 (large diameter) function as spacers.

[0007] Furthermore, since several of the conductive particles of particle shape d10 (small diameter) are arranged in a chain shape in the thickness direction of the anisotropic conductive film to form a conductive path, the anisotropic conductivity in the thickness direction of the anisotropic conductive film is ensured not only by the conductive paths formed by the conductive particles of particle shape d90 (large diameter), but also by the conductive paths formed by the conductive particles of particle shape d10 (small diameter).

[0008] Therefore, in the anisotropic conductive film of Patent Document 1, the conductive paths formed by the individual (single) conductive particles of the particle size d90 (large diameter) and the conductive paths formed by the conductive particles of the particle size d10 (small diameter) ensure the anisotropic conductivity in the thickness direction of the anisotropic conductive film, while the spacers can prevent excessive deformation of the anisotropic conductive film (see claim 1, paragraphs 0009 to 0043, and Figures 1 to 4).

[0009] Patent Document 2 (Japanese Patent No. 5476221) discloses an anisotropic conductive film having a structure in which conductive particles, each of which is formed by coating the surface of a substrate particle with a nickel-containing nickel conductive layer, are dispersed in an insulating binder resin. The nickel conductive layer is preferably a nickel alloy layer, more preferably a nickel alloy plating layer. The outer surface of the nickel conductive layer is covered with a coating containing nickel oxide or nickel hydroxide. When the test head is pressed against the wafer, the coating containing nickel oxide or nickel hydroxide that coats the outer surface of the nickel conductive layer is destroyed. This coating prevents the nickel conductive layer from being modified by corrosive gases in the atmosphere, while the coating is destroyed during use, allowing electrical continuity between the electrodes of the test head and the terminals (electrodes) on the wafer via the nickel conductive layer (see claim 5, paragraphs 0024 to 0084, and Figures 1 to 3).

[0010] Patent Document 3 (JP 2021-064591 A) discloses an anisotropic conductive film having a structure in which coated particles, each of which has a conductive surface and is coated with an insulating layer, are dispersed in an insulating resin. The insulating layer includes a non-conductive first material and a non-conductive second material, and the first material and the second material have opposite polarities of zeta potential measured at 25°C and pH 7. The conductive particles are, for example, configured by covering at least a portion of the surface of a core material made of a non-conductive or conductive material with a conductive coating made of a conductive material. The conditions related to the polarity of the zeta ionization are intended to increase adhesion between the first material and the second material to form a dense insulating layer and to prevent peeling of the insulating layer from the conductive particles, thereby improving the insulation reliability of the coated particles. When the test head is pressed against the wafer, the insulating layer covering the surface of the conductive particles is destroyed, making it possible to establish electrical continuity between the electrodes of the test head and the terminals (electrodes) on the wafer via the surfaces of the conductive particles (see summary, claim 14, paragraphs 0016-0154, and Figures 1-2).

[0011] Patent Document 4 (JP 2022-041178 A) discloses coated particles formed by coating conductive particles having a metal coating formed on the surface of a core material with an insulating layer. The insulating layer contains a block copolymer having a hydrophobic portion and a hydrophilic portion, and an inorganic compound is supported in the hydrophilic portion of the block copolymer. The inorganic compound supported on the insulating layer successfully penetrates the electrode, making it easier for the conductive particles to be fixed to the electrode. This allows the coated particles to exhibit appropriate elasticity while improving conductivity with the electrode during electrical connection during the formation of electronic circuits. In the coated particles, the insulating layer covering the conductive particles is destroyed to establish electrical conductivity between the electrodes of the test head and the terminals (electrodes) on the wafer, similar to Patent Documents 2 and 3 (see Abstract, paragraphs 0014-0119, and Figures 1-7).

[0012] Japanese Patent No. 5755527 Japanese Patent No. 5476221 Japanese Patent Application Laid-Open No. 2021-064591 Japanese Patent Application Laid-Open No. 2022-041178

[0013] In the anisotropic conductive film of Patent Document 1, when a test head electrode arranged on one side is pressed against a circuit terminal (electrode) on a wafer arranged on the other side, the individual (single) conductive particles with the particle size d90 (large diameter) function as spacers. Therefore, excessive pressure is not applied to the anisotropic conductive film, thereby suppressing excessive deformation. This anisotropic conductive film can effectively improve its durability and thereby ensure improved electrical characteristics. However, ICs are likely to become even smaller and more highly integrated, and the number of contacts is increasing. Therefore, existing anisotropic conductive films, including this anisotropic conductive film, are required to further improve high-frequency characteristics by further reducing resistance and to achieve higher resolution to accommodate finer pitches. Furthermore, to achieve these requirements, it is also necessary to improve contact stability with IC electrodes (terminals), increase current capacity as ICs become smaller and more integrated, and improve durability.

[0014] On the other hand, the anisotropic conductive film of Patent Document 2 is configured to obtain electrical conduction through the nickel conductive layer by applying a high load to destroy the coating containing nickel oxide or nickel hydroxide that coats the outer surface of the nickel conductive layer. Similarly, the anisotropic conductive film of Patent Document 3 is configured to obtain electrical conduction through the surface of the conductive particle by applying a high load to destroy the insulating layer that coats the surface of the conductive particle. The coated particles of Patent Document 4 are also configured to obtain electrical conduction through the insulating layer that coats the conductive particle by applying a high load, and are therefore similar to Patent Documents 2 and 3.

[0015] For this reason, the anisotropic conductive films of Patent Documents 2 and 3 and the coated particles of Patent Document 4 both have the drawback of increasing contact resistance and making the contact unstable when the electrodes of the test head are pressed against the terminals (electrodes) on the wafer. This means that even if these anisotropic conductive films or coated particles are used, it is not possible to meet the above-mentioned demands, such as improving contact stability with the electrodes (terminals) of ICs, increasing current due to miniaturization and high integration of ICs, and improving durability.

[0016] The present invention has been made in consideration of the above circumstances, and aims to provide an anisotropic conductive film that can improve high-frequency characteristics and increase resolution by reducing the contact resistance (electrical resistance) when the electrodes of a test head are pressed against the terminals (electrodes) on a wafer compared to conventional methods, and that can improve and maintain contact stability, increase current capacity (increase in allowable current), and improve durability by reducing the contact pressure (contact force) when the electrodes of a test head are pressed against the terminals (electrodes) on a wafer compared to conventional methods, a conductive connector using the anisotropic conductive film, and a conductive structure that is suitable for use with the anisotropic conductive film and the conductive connector.

[0017] Further objects of the present invention not specifically described herein will become apparent from the following description and accompanying drawings.

[0018] (1) An anisotropic conductive film of the present invention comprises: an insulating thin film made of an elastic insulating polymer material; and a plurality of substantially spherical particles made of a substance exhibiting topological antiferromagnetic properties dispersed within the insulating thin film; the plurality of particles form a plurality of conductive parts that are spaced apart in the in-plane direction within the insulating thin film so as to prevent electrical conduction in the in-plane direction of the insulating thin film, allowing electrical conduction in the thickness direction of the insulating thin film; each of the plurality of particles has magnetic anisotropy and its direction of easy magnetization is oriented in the thickness direction of the insulating thin film; each of the plurality of particles has a south pole region and a north pole region formed at two ends in a direction along the easy magnetization direction, so that magnetic flux of a virtual magnetic field is concentrated in the south pole region and the north pole region, and further has a plurality of spin flow path candidates (magnetic circuits) connecting the south pole region and the north pole region; and during operation, a voltage is applied between the south pole region and the north pole region along the easy magnetization direction, thereby (a) the inside of each of the plurality of particles becomes superconducting; (b) a spin current flows through one of the plurality of spin current path candidates (magnetic circuits) in the region between the south pole region and the north pole region; (c) an electric current flows in the region from the outside to the south pole region of the particle and in the region from the outside to the north pole region of the particle; and (d) an electric current-spin current conversion occurs in the south pole region and the north pole region, thereby realizing electrical conduction in the thickness direction of the insulating thin film through the conductive portion.

[0019] As described above, the anisotropic conductive film of the present invention has a plurality of conductive portions that are spaced apart in the in-plane direction within the insulating thin film and enable electrical conduction in the thickness direction of the insulating thin film, so that electrical conduction in the in-plane direction of the insulating thin film does not occur due to the plurality of particles dispersed in the insulating thin film, and therefore electrical conductivity is imparted only in the thickness direction of the insulating thin film, and therefore has anisotropic conductivity.

[0020] Furthermore, each of the plurality of particles is substantially spherical, has magnetic anisotropy, and its easy magnetization direction is oriented in the thickness direction of the insulating thin film. The south pole region and the north pole region are formed at two ends along the easy magnetization direction, respectively. The magnetic flux of a virtual magnetic field is concentrated in the south pole region and the north pole region. Therefore, when a voltage is applied between the south pole region and the north pole region along the easy magnetization direction during operation, (a) the interior of each of the plurality of particles becomes superconducting, (b) a spin current flows in the region between the south pole region and the north pole region, (c) an electric current flows in the region from the outside to the south pole region of the particle and in the region from the outside to the north pole region of the particle, and (d) a current-spin current conversion occurs in the south pole region and the north pole region.

[0021] As a result of these (a) to (d), electrical conduction through the conductive portion in the thickness direction of the insulating thin film is achieved with extremely low resistance.

[0022] In the anisotropic conductive film of the present invention, electrical conduction in the thickness direction of the insulating thin film is achieved through the conductive portions as described above, so that the electrical resistance of the anisotropic conductive film becomes extremely low, for example, to the same level as when superconductivity occurs.

[0023] Furthermore, by realizing such extremely low electrical resistance, the high frequency characteristics of the anisotropic conductive film are improved, and it is also possible to increase the current capacity thereof.

[0024] Furthermore, since the plurality of conductive parts are formed from a material exhibiting topological antiferromagnetic properties and have magnetic anisotropy with their easy direction of magnetization oriented in the thickness direction of the insulating thin film, it is possible to make the arrangement pitch of the plurality of conductive parts as fine as the particle diameter of the particles. Therefore, even higher resolution than before is possible, and it is also possible to accommodate finer pitches that will be required due to the further miniaturization and high integration of ICs in the future.

[0025] Furthermore, it is presumed that the spin current flowing inside the plurality of conductive parts passes through a potential barrier and conducts due to the quantum mechanical tunneling effect without destroying the insulating film, such as an oxide film, present on the surface of the contact object, such as an electrode or terminal, and therefore, simply by pressing the contact object against the insulating thin film with an extremely low pressure, the contact object and the plurality of conductive parts become conductive with an extremely small contact pressure. Therefore, contact stability is improved compared to conventional methods.

[0026] Furthermore, as described above, simply pressing the contact object against the insulating thin film with an extremely low contact pressure electrically connects the contact object to the plurality of conductive parts, thereby greatly reducing the amount of displacement of the insulating thin film, thereby improving the durability of the anisotropic conductive film.

[0027] (2) In a preferred example of the anisotropic conductive film of the present invention, each of the plurality of conductive portions is formed from a single particle, and the diameter of the particle is set to be larger than the thickness of the insulating thin film so that the ends of the particle protrude on both sides of the insulating thin film when the insulating thin film is not deformed by pressure.

[0028] In this example, by adjusting the strength of the magnetic field applied to the particles to impart magnetic anisotropy, it is possible to set the level of magnetic anisotropy of each particle forming each of the conductive parts to a high level (e.g., the maximum level) at which the magnetic anisotropy is not disturbed, which has the advantage of extremely low resistance to the spin current flowing through the conductive parts.

[0029] (3) In another preferred example of the anisotropic conductive film of the present invention, each of the plurality of conductive parts is formed from a single cluster consisting of a plurality of the particles arranged in parallel in the thickness direction of the insulating thin film, and the length of the cluster in the thickness direction of the insulating thin film is set to be larger than the thickness of the insulating thin film so that ends of the particles are exposed on both sides of the insulating thin film when the insulating thin film is not deformed by pressure.

[0030] In this example, by minimizing the number of particles arranged in the in-plane direction of the insulating thin film within the cluster and adjusting the strength of the magnetic field applied to impart magnetic anisotropy to the particles, it is possible to set the level of magnetic anisotropy of a single cluster forming each of the multiple conductive parts to a high level (e.g., a level slightly lower than the maximum level) that minimizes the disturbance of the magnetic anisotropy. This has the advantage of suppressing the current resistance between the particles within the cluster while extremely suppressing the resistance of the spin current flowing through the conductive parts.

[0031] (4) In yet another preferred embodiment of the anisotropic conductive film of the present invention, the insulating thin film is in the form of a sheet that is substantially inelastic in its in-plane direction and has flexibility (deformability) in its thickness direction.

[0032] In this example, when the insulating thin film is brought into contact with a contact object such as an electrode or a terminal, the insulating thin film easily elastically deforms in its thickness direction in accordance with the unevenness present on the surface of the contact object, thereby absorbing the unevenness. On the other hand, the insulating thin film hardly expands or contracts in its in-plane direction upon contact with the contact object, which is advantageous in that there is no risk of the arrangement positions of the multiple conductive parts changing and causing problems such as poor conduction.

[0033] (5) In yet another preferred embodiment of the anisotropic conductive film of the present invention, the insulating topological antiferromagnetic material forming the particles is NiO (nickel oxide) or MnO (manganese oxide). In this case, it is preferable to use metallic Ni or metallic Mn, which is the source of NiO or MnO, refined by the carbonyl method. This is because, according to research by the present inventors, to the extent currently known, the most favorable results were obtained in two aspects: the demonstration of electric current-spin current conversion and the demonstration of function as a type II superconductor, when metallic Ni or metallic Mn refined by the carbonyl method was used.

[0034] In addition to NiO and MnO, Cr ２ O ３ , Mn ３ Ge, Mn ３Sn, MnS, MnTe, MnF ２ , FeF ２ , FeCl ２ , FeO, CoCl ２ , CoO, NiCl ２ Among these, MnTe (307K), FeO (298K), CoO (291K), and Cr (308K), which have Neel temperatures of 0°C or higher, are preferred because their antiferromagnetic properties can be easily utilized.

[0035] (6) In yet another preferred embodiment of the anisotropic conductive film of the present invention, the particles are approximately spherical particles having a diameter in the range of approximately 0.1 μm to 10 μm, which are formed by aggregating microparticles made of a substance exhibiting topological antiferromagnetic properties, and the surfaces of the approximately spherical particles have microprotrusions (concavities and depressions) formed by the microparticles with a height difference in the range of approximately 10 nm to 100 nm.

[0036] In this example, the microparticles made of insulating topological antiferromagnetic material can be made to contain many defects (microvoids, lattice defects, impurities, etc.) that function as paths for magnetic flux and spin current, and there is also the advantage that many similar defects can remain in the particles formed by agglomerating the microparticles.

[0037] (7) In yet another preferred embodiment of the anisotropic conductive film of the present invention, the thickness of the insulating thin film is less than twice the median diameter of the particles.

[0038] In this example, the thickness of the insulating thin film is set to be less than twice the median diameter of the particles, so that the single particles are reliably arranged at intervals in the in-plane direction within the insulating thin film, which has the advantage of reliably obtaining a film (single particle film) in which the single particles are arranged at intervals in a row within the insulating thin film.

[0039] (8) In yet another preferred embodiment of the anisotropic conductive film of the present invention, the magnetic anisotropy of the particles is controlled by a magnetic field (e.g., 10 ２±１ This is done by applying a 100 Hz (Gauss) voltage.

[0040] In this example, excessive aggregation of the particles is suppressed during the formation of the insulating thin film, eliminating the risk of the particles flowing in the in-plane direction of the insulating thin film, thereby providing the advantage of ensuring the generation of spin currents in the multiple conductive parts.

[0041] (9) A conductive connector of the present invention is a conductive connector for an inspection device, which is in contact with a plurality of terminals of the inspection device and transmits and receives electrical signals between the inspection device and the inspection device, and is characterized in that it comprises: a first anisotropic conductive film formed of the anisotropic conductive film described in any one of (1) to (8) above; a second anisotropic conductive film formed of the anisotropic conductive film described in any one of (1) to (8) above, laminated on the first anisotropic conductive film; and a plurality of movable electrodes disposed between the first anisotropic conductive film and the second anisotropic conductive film, which are movable in the lamination direction of the second anisotropic conductive film, and the plurality of movable electrodes are disposed at positions that align with the positions of the plurality of terminals, respectively.

[0042] The conductive connector of the present invention is configured to include a first anisotropic conductive film formed from the anisotropic conductive film described in any one of (1) to (8) above, a second anisotropic conductive film formed from the anisotropic conductive film described in any one of (1) to (8) above, laminated on the first anisotropic conductive film, and a plurality of movable electrodes disposed between the first anisotropic conductive film and the second anisotropic conductive film, and movable in the lamination direction of the second anisotropic conductive film. Therefore, when pressure is applied in the lamination direction while the test object is sandwiched between the test device and the test apparatus, each of the plurality of movable electrodes contacts and is electrically connected to one or more corresponding conductive portions of the first anisotropic conductive film, and also contacts and is electrically connected to one or more corresponding conductive portions of the second anisotropic conductive film. Therefore, by transmitting and receiving electrical signals between the test object and the test device, the test device can perform a desired test on the test object.

[0043] Since each of the first anisotropic conductive film and the second anisotropic conductive film is formed from the anisotropic conductive film described in any one of (1) to (8) above, the electrical resistance of the first anisotropic conductive film and the second anisotropic conductive film is extremely low for the same reason as described above for the anisotropic conductive film described in (1). For example, the electrical resistance becomes extremely low, comparable to the level at which superconductivity occurs. Since the electrical resistance of the conductive connector of the present invention is simply the extremely low electrical resistance of the first anisotropic conductive film and the second anisotropic conductive film plus the electrical resistance of the multiple movable electrodes, the electrical resistance of the conductive connector is also kept to a level just slightly greater than the sum of the electrical resistances of the first anisotropic conductive film and the second anisotropic conductive film.

[0044] Furthermore, by achieving such extremely low electrical resistance for the first anisotropic conductive film and the second anisotropic conductive film, the high frequency characteristics of the conductive connector are improved and it is also possible to increase the current capacity.

[0045] Furthermore, for the same reasons as those described above for the anisotropic conductive film (1), it is possible to achieve even higher resolution than before, and it is also possible to accommodate the finer pitches that will be required in the future due to the further miniaturization and high integration of ICs.

[0046] Furthermore, for the same reason as described above for the anisotropic conductive film in (1), when the test object is sandwiched between the test device and the test equipment, only an extremely low pressure is applied in the stacking direction, in other words, with an extremely small contact pressure, each of the plurality of movable electrodes is electrically connected to one or more corresponding conductive portions of the first anisotropic conductive film and one or more corresponding conductive portions of the second anisotropic conductive film, thereby improving contact stability compared to conventional methods.

[0047] Furthermore, as described above, when the conductive connector is sandwiched between the test object and the test device, simply by applying an extremely low pressure in the stacking direction, each of the plurality of movable electrodes becomes conductive with one or more corresponding conductive portions of the first anisotropic conductive film and one or more corresponding conductive portions of the second anisotropic conductive film, respectively, so that the amount of displacement of the first anisotropic conductive film and the second anisotropic conductive film can be made extremely small, thereby improving the durability of the conductive connector.

[0048] (10) In a preferred example of the conductive connector of the present invention, each of the plurality of movable electrodes is formed from a substantially disk-shaped rigid material, and the plurality of movable electrodes are movable between the first anisotropic conductive film and the second anisotropic conductive film without using a retaining layer, and when pressure is applied in the stacking direction while sandwiched between the test object and the test device, each of the plurality of movable electrodes is configured to contact and be conductive with one or more corresponding conductive portions of the first anisotropic conductive film, and to contact and be conductive with one or more corresponding conductive portions of the second anisotropic conductive film.

[0049] In this example, each of the plurality of movable electrodes is formed from a rigid material having an approximately circular disk shape, and the plurality of movable electrodes are movable between the first anisotropic conductive film and the second anisotropic conductive film without using a retaining layer, which has the advantage of more reliable contact and conduction between each of the plurality of movable electrodes and the corresponding one or more conductive portions of the first anisotropic conductive film and the corresponding one or more conductive portions of the second anisotropic conductive film.

[0050] (11) In another preferred embodiment of the conductive connector of the present invention, the conductive connector further comprises a third anisotropic conductive film laminated on the first anisotropic conductive film and the second anisotropic conductive film on the side of the first anisotropic conductive film of the plurality of movable electrodes or on the side of the second anisotropic conductive film of the plurality of movable electrodes, and the third anisotropic conductive film is formed by the anisotropic conductive film according to any one of (1) to (8) above.

[0051] In this example, since the third anisotropic conductive film is further added, there is an advantage that when absorbing the dimensional difference in the gap between the inspection object and the inspection device, the amount of displacement of each of the first anisotropic conductive film, the second anisotropic conductive film, and the third anisotropic conductive film can be reduced compared to when only the first anisotropic conductive film and the second anisotropic conductive film are used.

[0052] (12) A conductive structure of the present invention is a conductive structure that can be used as a conductive portion of an anisotropic conductive film, and includes at least one substantially spherical particle formed of a material exhibiting topological antiferromagnetic properties, the particle having magnetic anisotropy and having a south pole region and a north pole region formed at two ends in a direction along its easy magnetization direction, and when a voltage is applied between the south pole region and the north pole region, (a) the surface and interface of the microparticle enter a topological superconducting state, (b) a spin current flows in a portion between the south pole region and the north pole region, (c) a current flows in a portion from the outside to the south pole region of the particle and in a portion from the outside to the north pole region of the particle, and (d) a current-spin current conversion occurs in the south pole region and the north pole region, thereby realizing electrical conduction through the particle.

[0053] In the conductive structure of the present invention, electrical conduction is achieved through the conductive structure as described above, and therefore the electrical resistance of the anisotropic conductive film using the conductive structure becomes extremely low, for example, to the same level as when superconductivity occurs.

[0054] Furthermore, by realizing such extremely low electrical resistance, the high frequency characteristics of the anisotropic conductive film are improved, and it is also possible to increase the current capacity thereof.

[0055] Furthermore, since the particles are formed from a material that exhibits topological antiferromagnetic properties and has magnetic anisotropy, by orienting the easy magnetization direction of the particles in the thickness direction of the anisotropic conductive film, it is possible to make the arrangement pitch of the multiple conductive parts arranged inside the anisotropic conductive film as fine as the particle diameter of the particles. Therefore, even higher resolution than before is possible, and it is also possible to respond to the finer pitches that will be required for future ICs to be further miniaturized and highly integrated.

[0056] Furthermore, it is presumed that the spin current flowing inside the particles passes through a potential barrier and conducts due to the quantum mechanical tunneling effect without destroying the insulating film, such as an oxide film, present on the surface of the contact object, such as an electrode or terminal, so that simply by pressing the contact object against the anisotropic conductive film with an extremely low pressure, in other words, the contact object and the multiple conductive parts become conductive with an extremely small contact pressure, thereby improving contact stability compared to conventional methods.

[0057] Furthermore, as described above, simply pressing the contact object against the anisotropic conductive film with an extremely low pressure / contact pressure electrically connects the contact object to the plurality of conductive parts, thereby greatly reducing the amount of displacement of the anisotropic conductive film, thereby improving the durability of the anisotropic conductive film.

[0058] (13) In a preferred example of the conductive structure of the present invention, the substance exhibiting topological antiferromagnetic properties that forms the particles is NiO (nickel oxide) or MnO (manganese oxide). In this case, it is preferable to use metallic Ni or metallic Mn, which is the source of NiO or MnO, refined by the carbonyl method. According to the research of the present inventors, to the extent currently known, the most favorable results were obtained in two aspects: the demonstration of electric current-spin current conversion and the demonstration of function as a type II superconductor, when metallic Ni or metallic Mn refined by the carbonyl method was used.

[0059] In addition to NiO and MnO, Cr ２ O ３ , Mn ３ Ge, Mn ３ Sn, MnS, MnTe, MnF ２ , FeF ２ , FeCl ２ , FeO, CoCl ２ , CoO, NiCl ２ Among these, MnTe (307K), FeO (298K), CoO (291K), and Cr (308K), which have Neel temperatures of 0°C or higher, are preferred because their antiferromagnetic properties can be easily utilized.

[0060] (14) In another preferred example of the conductive structure of the present invention, the particles are approximately spherical particles having a diameter in the range of approximately 0.1 μm to 10 μm, which are formed by aggregating microparticles made of a material exhibiting the topological antiferromagnetic properties, and the surfaces of the approximately spherical particles have microprotrusions formed by the microparticles and having a height difference in the range of approximately 10 nm to 100 nm.

[0061] In this example, the microparticles made of a material exhibiting the topological antiferromagnetic properties can be made to contain many defects (microvoids, lattice defects, impurities, etc.) that function as paths for magnetic flux and spin current, and there is also the advantage that many similar defects can remain in the particles formed by agglomerating the microparticles.

[0062] (15) In yet another preferred embodiment of the conductive structure of the present invention, the magnetization of the particles is controlled by a magnetic field (e.g., 10 ２±１ This is done by applying a 100 Hz (Gauss) voltage.

[0063] In this example, excessive aggregation of the particles is suppressed during the formation of the insulating thin film, eliminating the risk of the particles flowing in the in-plane direction of the insulating thin film, which provides the advantage of ensuring the generation of spin currents inside the particles.

[0064] The anisotropic conductive film, conductive connector, and conductive structure of the present invention have the advantages of being able to achieve lower resistance, improved high-frequency characteristics and higher resolution, improved contact stability due to reduced contact pressure, higher current, and improved durability compared to conventional methods.

[0065] 1A is a schematic cross-sectional view showing the state of use of the conductive connector according to the first embodiment of the present invention; 1B is a schematic exploded explanatory view showing the configuration of the conductive connector; 1C is a conceptual diagram showing clusters dispersed within the anisotropic conductive film (cluster film) of the conductive connector. 1A is an explanatory view showing the microparticles forming the particles dispersed within the anisotropic conductive film (single particle film and cluster film) used in the conductive connector of FIG. 1; 1B is a conceptual diagram showing the configuration of the particles; 1C is an electron microscope photograph of the particles. 1A is a graph comparing the PRESS-ON load measured when the particles shown in FIG. 2B were manufactured by the carbonyl method and the atomization method; 1B is a diagram showing an overview of the measurement probe; 1C is a photograph of the appearance of the measurement device used to measure the PRESS-ON load (the load at which conduction begins due to pressure). 1 shows a manufacturing method for anisotropic conductive films (single particle film and cluster film) used in the conductive connector of FIG. 1 , where (a) is a conceptual diagram of the manufacturing apparatus used in the manufacturing method, (b) is a conceptual diagram showing the magnetization state of particles inside a single particle film, and (c) is a conceptual diagram showing the magnetization state of particles inside a cluster film. This is a table showing the results of comparative performance tests conducted on a probe manufactured using the conductive connector of FIG. 1 and probes of Comparative Examples 1 and 2. This is an explanatory diagram showing that when current is passed between the south and north pole regions of particles contained in the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1 , where skyrmions are concentrated and generated, a huge virtual magnetic field of the skyrmions is concentrated in the south and north pole regions, resulting in the quantum effect of the particles. As a result, one of the multiple spin current path candidates generated between the south and north pole regions is selected, and a spin current flows through it. This is an explanatory diagram showing an outline of the manufacturing process for the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1. 2 is an explanatory diagram showing an outline of a manufacturing process of an anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1.

[0023] FIG.1 is an explanatory diagram showing a process of imparting magnetic anisotropy and quantum effects to particles (and the microparticles forming them) contained in the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1 , and how the surface layer and interface of the particles (and the microparticles) become topologically superconducting and the interior becomes a ferromagnetic state due to the magnetic anisotropy and quantum effects.

[0023] FIG. 1 is an explanatory diagram showing how the magnetic anisotropy imparted to the particles (and the microparticles forming them) contained in the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1 changes depending on the strength of the applied magnetic field.

[0024] FIG. 1 is an explanatory diagram showing how the formation of spin current paths and current paths differs depending on the magnetic anisotropy imparted to the particles when the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1 contains only separated particles, only separated particle clusters, or only non-separated particle clusters. 1A is an explanatory diagram showing, in comparison with a conventional example, how electrical conduction is achieved when a spin current penetrates the insulating film of particles contained in the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1 ; (b) is an explanatory diagram schematically showing the current path and spin current path formed in the particle.

[0023] An explanatory diagram showing how highly efficient spin current is generated by passing current through particles contained in the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1 along their magnetic anisotropy.

[0024] An explanatory diagram showing south and north polar regions where skyrmions are concentrated and generated within particles contained in the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1 , and multiple spin current path candidates generated between the south and north polar regions.

[0025] (a) is a planar explanatory diagram of the anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1 ; (b) is a cross-sectional explanatory diagram showing a schematic diagram of spin current flowing through a selected portion of multiple spin current path candidates. 2 is an explanatory diagram showing spin currents flowing through conductive portions of different sizes in an anisotropic conductive film (single particle film, cluster film) used in the conductive connector of FIG. 1. FIG.Fig. 2 is a flowchart showing an outline of a method for manufacturing an anisotropic conductive film (single particle film, cluster film) used in the conductive connector of Fig. 1. Fig. 3 is an explanatory diagram showing an example of a circuit configuration when measuring the electrical resistance of the conductive connector of Fig. 1 by a four-terminal measurement method. Fig. 4 is a schematic cross-sectional view showing the configuration of a conductive connector according to a second embodiment of the present invention.

[0066] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, specific values, etc. shown in the embodiments are merely examples for facilitating understanding of the present invention and do not limit the present invention unless otherwise specified. Elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0067] (Configuration of the conductive connector 100 according to the first embodiment of the present invention) To facilitate understanding, the conductive connector 100 according to the first embodiment of the present invention will be described below, and then the first anisotropic conductive film 110, the second anisotropic conductive film 130, and the movable electrode 120 used in the conductive connector 100 will be described.

[0068] Fig. 1(a) is a schematic diagram illustrating the state of use of a conductive connector 100 according to a first embodiment of the present invention, and Fig. 1(b) is an exploded explanatory view illustrating the structure of the conductive connector 100. Fig. 1(c) is a conceptual diagram illustrating particles 200 and clusters 210 thereof used in the conductive connector 100.

[0069] In a wafer test during an IC manufacturing process, the operation of a circuit 302 constituting an IC formed on a silicon wafer 300 to be tested is confirmed. The conductive connector 100 shown in FIG. 1( a) is used as a probe provided on a test head 400 of a semiconductor test device (not shown). When performing the wafer test, a plurality of terminals 304 of the circuit 302 on the wafer 300 are electrically connected to a plurality of electrodes 404 corresponding to the terminals 304 of the test head 400 via the conductive connector 100, and in this state, electrical signals are transmitted and received between the semiconductor test device and the circuit 302 to test the electrical characteristics of the circuit 302. The conductive connector 100 according to the first embodiment of the present invention is used for such an application.

[0070] The conductive connector 100 according to the first embodiment of the present invention has the following configuration. That is, as shown in FIG. 1( a), from the circuit 302 of the wafer 300 toward the test head 400 of the semiconductor testing device (upward in FIG. 1( a)), a single particle film (first anisotropic conductive film) 110, multiple disk-shaped (coin tablet-shaped) movable electrodes 120, and a cluster film (second anisotropic conductive film) 130 are stacked in this order, forming a three-layer structure. The multiple disk-shaped movable electrodes 120 are spaced apart in a single plane in the space between the single particle film 110 and the cluster film 130, and are generally parallel to the single particle film 110 and the cluster film 130. The single particle film 110 and the cluster film 130 are also generally parallel to each other.

[0071] Each electrode 404 of the test head 400 is positioned to overlap a terminal 304 at a corresponding position (i.e., directly below) on the wafer 300. Each movable electrode 120 is positioned to overlap both an electrode 404 of the test head 400 at a corresponding position (i.e., directly above) and a terminal 304 on the wafer 300 at a corresponding position (i.e., directly below).

[0072] 1(a) and 1(b), the first anisotropic conductive film 110 has a configuration in which particles 200 in a separated state are arranged at intervals in the in-plane direction, and only a single particle 200 exists in the thickness direction. Therefore, in the following description, the first anisotropic conductive film 110 is also referred to as a single particle film.

[0073] As shown in FIG. 1( b), the monoparticle film (first anisotropic conductive film) 110 has a configuration in which a plurality of particles 200 are dispersed to form a monoparticle layer in an insulating thin film 112 made of an elastic insulating polymer material. Within the insulating thin film 112, the particles 200 are arranged at intervals along the in-plane direction of the insulating thin film 112, but only a single particle 200, in other words, a separate particle 200, exists in the thickness direction of the insulating thin film 112. In other words, no clusters 210 of particles 200 exist within the insulating thin film 112.

[0074] The separated particles 200 present inside the insulating thin film 112 are spaced apart in the in-plane direction of the insulating thin film 112, forming conductive portions 114 that enable electrical conduction in the thickness direction of the insulating thin film 112. The distance between two adjacent particles 200 is set to a value such that, even when the single particle film 110 is brought into contact with a terminal 304 on the wafer 300 and electrical conduction occurs in the thickness direction of the insulating thin film 112 at the conductive portions 114 formed by the particles 200, electrical conduction does not occur between the particles 200 (conductive portions 114).

[0075] 1B, the upper and lower ends of each particle 200 (i.e., each conductive portion 114) are exposed on the upper and lower surfaces of the insulating thin film 112, respectively. Therefore, the upper end of each particle 200, i.e., each conductive portion 114, is always in contact with the movable electrode 120 located at the corresponding position (i.e., directly above). On the other hand, the lower end of each particle 200, i.e., each conductive portion 114, can be brought into contact with a terminal 304 on the wafer 300 located at the corresponding position (i.e., directly below). Then, when the lower end of each conductive portion 114 is brought into contact with a terminal 304 on the wafer 300 located at a corresponding position (directly below) thereof, and a voltage is applied across the conductive portion 114 (the particle 200), the quantum effect possessed by the particle 200 is exerted, and a flow of electron spins (spin current) passes through the conductive portion 114 (the particle 200) in the vertical direction (in the thickness direction of the insulating thin film 112). As a result, electrical conduction can be achieved between the movable electrode 120 located at a corresponding position (i.e., directly above) of the conductive portion 114 (the particle 200) and the terminal 304 located at a corresponding position (i.e., directly below) of the conductive portion 114 (the particle 200). Details of the quantum effect possessed by the particle 200 will be described later.

[0076] The second anisotropic conductive film 130 differs from the first anisotropic conductive film 110 in that it has a configuration in which a plurality of particles 200 (two particles in FIGS. 1(a) and 1(b)) aggregated in the thickness direction, i.e., clusters 210 of the particles 200, are arranged at intervals in the in-plane direction, with only a single cluster 210 existing in the thickness direction. Therefore, in the following description, the second anisotropic conductive film 130 is also referred to as a cluster film.

[0077] As shown in FIG. 1B, the cluster film 130 has a configuration in which a plurality of particles 200, the same as those used in the monoparticle film 110, are dispersed in an insulating thin film 132 made of an elastic insulating polymer material. Inside the insulating thin film 132, the particles 200 are arranged at intervals along the in-plane direction of the insulating thin film 132. This is similar to the monoparticle film 110. However, the particles 200 arranged inside the insulating thin film 132 are aggregated in the thickness direction of the insulating thin film 132, forming clusters 210, and the clusters 210 of particles 200 are arranged at intervals along the in-plane direction of the insulating thin film 132. In this respect, it differs from the monoparticle film 110.

[0078] Note that only clusters 210 of particles 200 exist inside the cluster film 130. In other words, there are no particles 200 separated from one another like in the single particle film 110 inside the insulating thin film 132. Therefore, it can be said that inside the insulating thin film 132, clusters 210 of multiple particles 200 are arranged at intervals along the in-plane direction of the insulating thin film 132.

[0079] Clusters 210 of particles 200 present inside the insulating thin film 132 are spaced apart in the in-plane direction of the insulating thin film 132, forming conductive parts 134 that allow electrical conduction in the thickness direction of the insulating thin film 132. The distance between two adjacent clusters 210 is set to a value that prevents electrical conduction in the in-plane direction of the insulating thin film 132 between those clusters 210 (conductive parts 134) even when the cluster film 130 is brought into contact with the electrode 404 of the test head 400 and electrical conduction is established in the thickness direction of the insulating thin film 132 at the conductive parts 134 formed by those clusters 210.

[0080] 1B, the upper and lower ends of each cluster 210 (i.e., each conductive portion 134) are exposed on the upper and lower surfaces, respectively, of the insulating thin film 132. Therefore, the lower end of each cluster 210, i.e., each conductive portion 134, is always in contact with the movable electrode 120 located at the corresponding position (i.e., directly below). On the other hand, the upper end of each cluster 210, i.e., each conductive portion 134, can be brought into contact with the electrode 404 of the test head 400 located at the corresponding position (i.e., directly above). Then, after the upper end of each conductive portion 134 is brought into contact with the electrode 404 of the test head 400 located at the corresponding position (directly above), when a voltage is applied across the conductive portion 134 (the cluster 210), the quantum effect of the particles 200 contained in the cluster 210 is exerted, and a flow of electron spins (spin current) passes through the conductive portion 134 (the cluster 210) in the vertical direction (in the thickness direction of the insulating thin film 132). As a result, electrical conduction can be achieved between the movable electrode 120 located at the corresponding position (i.e., directly below) of the conductive portion 134 (the cluster 210) and the electrode 404 located at the corresponding position (i.e., directly above) of the conductive portion 134 (the cluster 210). This is similar to the single particle film 110. Details of the quantum effect of the particles 200 contained in the cluster 210 will be described later.

[0081] Clusters 210 of particles 200 can be easily formed by applying a magnetic field in the thickness direction of the cluster film 130 (insulating thin film 132) when forming the cluster film 130. This is because the applied magnetic field causes the particles 200 to aggregate in rows in the direction of the magnetic field, i.e., in the thickness direction of the cluster film 130 (insulating thin film 132).

[0082] If the strength of the applied magnetic field is too strong, more than the desired number of particles 200 will aggregate inside the insulating thin film 132 during film formation (before hardening), forming clumps rather than rows. If many particles 200 form clumps, there is a high possibility that electrical conduction will occur in the in-plane direction of the cluster film 130. Therefore, when forming the cluster film 130, a magnetic field of appropriate strength (for example, 10 ２±１ This is preferably done by applying a voltage (gauss).

[0083] 1(a) and 1(b) is configured using a single particle film (first anisotropic conductive film) 110 and a cluster film (second anisotropic conductive film) 130, in other words, two anisotropic conductive films of the present invention, but the present invention is not limited thereto. Three or more anisotropic conductive films of the present invention may also be used. Conventionally, stacking multiple anisotropic conductive films has been used to absorb the dimensional difference between the terminals 304 of the circuit 302 on the wafer 300 and the electrodes 404 of the test head 400 of the semiconductor test device. In this case, using three or four or more anisotropic conductive films of the present invention has the advantage of further reducing the amount of displacement of the anisotropic conductive film of each layer compared to the conductive connector 100 of the first embodiment, which uses two anisotropic conductive films of the present invention. This reduces the contact pressure between the anisotropic conductive film of each layer and the terminals 304 and electrodes 404, and also increases the durability of the conductive connector 100. (A conductive connector using three or more anisotropic conductive films of the present invention will be described in detail in the second embodiment of the present invention described later.)

[0084] From the viewpoint of insulation and durability, it is preferable to use a polymer material having a cross-linked structure for both the insulating thin film 112 used in the single particle film 110 and the insulating thin film 132 used in the cluster film 130. Specifically, room-temperature curing silicone rubber can be suitably used, but polymer materials other than silicone rubber can also be used as long as they have insulation and a cross-linked structure. For example, as described in Japanese Patent No. 5777477, which is owned by the present applicant, conjugated diene rubbers such as polybutadiene rubber, natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, and acrylonitrile-butadiene copolymer rubber, and hydrogenated products thereof; block copolymer rubbers such as styrene-butadiene-diene block copolymer rubber and styrene-isoprene block copolymer, and hydrogenated products thereof; chloroprene rubber, urethane rubber, polyester rubber, epichlorohydrin rubber, silicone rubber, ethylene-propylene copolymer rubber, and ethylene-propylene-diene copolymer rubber can be used.

[0085] The monoparticle film (first anisotropic conductive film) 110 has a configuration in which particles 200 are dispersed within an insulating thin film 112 made of an elastic insulating polymer material, and therefore has flexibility (variability) in its thickness direction. In other words, when pressure is applied to a given location, the thickness of the monoparticle film 110 at that location fluctuates (decreases) in response to the pressure, and returns to its original thickness when the pressure is removed. However, the monoparticle film 110 does not expand or contract in its in-plane direction (i.e., it is inelastic in the in-plane direction). Therefore, the monoparticle film 110 can absorb dimensional errors in the spacing between the terminals 304 and the movable electrode 120 of the wafer 300 and reliably contact the terminals 304 and the movable electrode 120 on both sides of the monoparticle film 110.

[0086] The cluster film (second anisotropic conductive film) 130 is similar to the single particle film 110. That is, the cluster film 130 has a configuration in which clusters 210 of particles 200 are dispersed inside an insulating thin film 132 made of an elastic insulating polymer material, and therefore has flexibility (variability) in its thickness direction but does not expand or contract in its in-plane direction (i.e., is inelastic in the in-plane direction). Therefore, the cluster film 130 can absorb dimensional errors in the gap between the electrodes 404 and the movable electrode 120 of the test head 400 and can reliably contact the electrodes 404 and the movable electrode 120 on both sides of the cluster film 130.

[0087] Therefore, the single particle film 110 and the cluster film 130 can absorb the dimensional error in the spacing between the terminal 304 and the electrode 404, respectively, and can reliably contact the terminal 304 and the electrode 404 on both sides thereof and the movable electrode 120.

[0088] Here, the movable electrode 120 is disk-shaped (coin tablet-shaped). The multiple movable electrodes 120 are arranged at positions corresponding to the pattern of the terminals 304 on the wafer 300 and the pattern of the electrodes 404 on the test head 400, in other words, in the same pattern as those patterns. There is no holding layer for holding these movable electrodes 120, and only the multiple movable electrodes 120 are arranged in a layered manner in the space between the single particle film 110 and the cluster film 130. Therefore, it can be said that the multiple movable electrodes 120 form a movable electrode layer.

[0089] A metal material having rigidity and desired conductivity can be suitably used for the movable electrode 120. Examples of the metal include elemental metals such as nickel (Ni), cobalt (Co), gold (Au), and aluminum (Al), and alloys thereof.

[0090] Furthermore, the thickness (height) of each movable electrode 120 needs to be 25% or less of the total thickness of the laminated monoparticulate film 110 and cluster film 130 (both of which are anisotropic conductive films). This is to avoid damage to each of the monoparticulate film 110 and cluster film 130 due to excessive pressure and to obtain high durability.

[0091] Furthermore, the displacement (compression amount) of the cluster film 130 arranged on the test head 400 side is calculated by multiplying the thickness of the cluster film 130 by the compression ratio, and this compression ratio is preferably 5% or less of the thickness of the cluster film 130. Therefore, for example, if the thickness of the cluster film 130 is 10 μm, the compression amount of the cluster film 130 should be a maximum of 5% of that thickness, i.e., 10 μm × 0.05 = 0.5 μm. In other words, the compression amount of the cluster film 130 should preferably be a maximum of 0.5 μm. This is a necessary condition for achieving both zero-force contact and high reliability. Note that if there are multiple cluster films 130 arranged on the test head 400 side, the thickness of the cluster film 130 can be replaced with the sum of the thicknesses of those multiple cluster films 130.

[0092] The movable electrode 120 can be easily formed by a known method, for example, the method described in Japanese Patent No. 5777477 owned by the present applicant.

[0093] Specifically, for example, a through-hole is first formed in an insulating sheet (e.g., polyimide resin), a mask layer is formed on the inner surface of the through-hole (e.g., a Cu layer is formed by electroless plating), and a rigid conductor is formed inside the mask layer (e.g., by electroplating using Ni). A polymeric material (e.g., silicone rubber) containing particles (e.g., magnetic metal particles such as Fe, Co, Ni, or alloy particles thereof (particles containing these metals)) is then applied to the rigid conductor so that it comes into contact with the rigid conductor. The polymeric material is then cross-linked and cured to form an elastic material, thereby forming an anisotropic conductive film (which forms the head of the movable electrode) bonded to the rigid conductor. The mask layer is then removed by etching. In this way, the rigid conductor can be made into a movable electrode that can move relative to the insulating sheet.

[0094] The anisotropic conductive film bonded and integrated with the movable electrode (formed from the rigid conductor) forms the flange-shaped head of the movable electrode. However, if the anisotropic conductive film is not required, the step of applying the polymer material containing the particles before cross-linking and hardening can be omitted. Furthermore, after the mask layer is removed, the insulating sheet that supports and guides the movable electrode remains around the movable electrode. However, the insulating sheet can be removed by etching or the like. Therefore, in the method described in Japanese Patent No. 5777477, if the step of applying the polymer material containing the particles before cross-linking and hardening is omitted and the insulating sheet is removed by etching or the like, a coin tablet-shaped movable electrode 120 having the configuration shown in Figures 1(a) and 1(b) can be obtained.

[0095] The reason for using the movable electrode 120 is as follows. Specifically, the particles 200, made of NiO, an insulating topological antiferromagnetic material, are made of metallic Ni, which is refined by the carbonyl method. Therefore, the surfaces of the metallic Ni particles used in the particles 200 have microprotrusions. Therefore, using metallic Ni refined by the carbonyl method provides favorable switching characteristics and excellent non-ohmic contact characteristics. However, the microprotrusions are easily crushed by pressure or impact during use, which is a drawback in that both of these characteristics are not sustainable. On the other hand, rigid particles (e.g., particles 200) held in an elastomer, such as the insulating thin films 112 and 132, have the advantage of providing a "soft, low-pressure contact" that makes the microprotrusions less likely to be crushed, thereby more easily maintaining both of these characteristics. Furthermore, when the rigid particles (particles 200) are indirectly brought into contact with the elastomer (insulating thin films 112 and 132) via the movable electrode 120, the stress on the elastomer (insulating thin films 112 and 132) is dramatically reduced. This improves the electrical properties of anisotropic conductive films such as the single particle film 110 and the cluster film 130, resulting in an anisotropic conductive film with a small thickness and excellent electrical properties. The movable electrode 120 is used because of these advantages.

[0096] Next, the particles 200 used in the conductive connector 100 according to the first embodiment of the present invention will be described.

[0097] The particles 200 used in the conductive connector 100 according to the first embodiment, having the above-described configuration, are formed from nickel oxide (NiO), a material that exhibits topological antiferromagnetic properties, and exhibit topological antiferromagnetic properties. However, the material of the particles 200 is metallic nickel (Ni), a material that exhibits ferromagnetic properties. Generally, topological antiferromagnetic materials have the unique property of being insulators (electrically non-conductive) internally, but conductors (electrically conductive) on the surface. Furthermore, this property remains unchanged even after repeated aggregation and crushing of the material. Here, "antiferromagnetic" refers to the magnetism of a material in which adjacent spins are aligned in opposite directions and have no overall magnetic moment. Note that antiferromagnetic materials (antiferromagnets) exhibit this property only at low temperatures below the Neel temperature. This also applies to the particles 200 exhibiting topological antiferromagnetic properties. Moreover, since the particle 200 is formed from an aggregate of the microparticles 202 (see FIGS. 2(a) and 2(b)), the same applies to the microparticles 202.

[0098] The particles 200 (and the microparticles 202 that form them) are produced as follows. The anisotropic conductivity and quantum effect of the particles 200 (and microparticles 202) are exhibited in the process of adding the approximately spherical particles 200 (which are aggregates of microparticles 202) shown in FIG. 2( b ) together with a binder to an insulating polymer material prepared for the single particle film (first anisotropic conductive film) 110 or the cluster film (second anisotropic conductive film) 130 before cross-linking and curing, and then forming the resulting raw material into a sheet to form the insulating thin film 112 or 132. The anisotropic conductivity and quantum effect thus exhibited in the particles 200 are then fixed (memorized) within the cross-linked and cured insulating thin film 112 or 132.

[0099] In the first embodiment, first, as shown in FIGS. 7 and 17, Ni ore is prepared as a raw material (see stage 1 in FIG. 7 and step S1 in FIG. 17). The Ni ore as a raw material contains voids, lattice defects, impurities, etc. inside, and has a low density. Specifically, the density is 1.7 to 3.5 g / cm. ３ The density of pure Ni crystal is 8.9 g / cm ３ Therefore, it can be seen that the density of the Ni ore is quite low. Next, by refining using the well-known carbonyl method (a process in which impure metals are converted into volatile compounds, which are then thermally decomposed to revert to the metal, thereby purifying the metal), roughly spherical microparticles 202 with diameters of several tens to several hundreds of nanometers are formed, as shown in Figure 2(a). The microparticles 202 thus obtained contain oxygen (O) because they are oxidized during the carbonyl method treatment. Therefore, the microparticles 202 are formed from NiO rather than Ni. However, it is presumed that the entire microparticle 202 is not oxidized; rather, Ni likely remains inside, with the interface and surface layer oxidized to NiO. For simplicity's sake, the following explanation will be given assuming that the microparticles 202 (as a whole) are NiO.

[0100] The surfaces of the NiO nanoparticles 202 thus formed have minute protrusions (unevenness). Furthermore, the interiors of the nanoparticles 202 contain minute voids, lattice defects, impurities, and the like (not shown). These play an important role in the process of developing and fixing magnetic anisotropy in the nanoparticles 202, as will be described later.

[0101] Next, the thus obtained microparticles 202 made of metallic Ni are fired or sintered at an appropriate temperature within the range of 300 to 1200°C by a known powder metallurgy method to form an aggregate (fired body or sintered body) of the microparticles 202.

[0102] Next, the agglomerates of the microparticles 202 thus obtained are crushed by a known milling method, then granulated and classified to obtain roughly spherical particles 200 having a diameter (median diameter) in the range of approximately 0.1 μm to 10 μm (see stage 2 in FIG. 7 and step S2 in FIG. 17). The roughly spherical particles 200 thus obtained are agglomerates of the microparticles 202 made of NiO, and therefore the particles 200 are also made of NiO.

[0103] The roughly spherical particles 200 thus obtained are those before the imparting of magnetic anisotropy and the manifestation of the quantum effect. In a later step of antiferromagnetic treatment (described later), the particles 200 (and the microparticles 202 that form them) are imparted with magnetic anisotropy and the manifestation and fixation of the quantum effect (see stage 3 in FIG. 7 and steps S3 and S4 in FIG. 17).

[0104] 2B, each particle 200 has protrusions (unevenness) 204 caused by the microparticles 202 formed on the surface of the particle 200. Furthermore, the interior of each particle 200 contains defects (microvoids, lattice defects, impurities, etc.) caused by the microparticles 202. The protrusions (unevenness) 204 and the defects of each particle 200 act as paths for magnetic flux and spin current (i.e., magnetic circuits).

[0105] The material for the approximately spherical particles 200 with magnetic anisotropy and quantum effects can be any substance that exhibits topological antiferromagnetic properties through post-treatment, such as heating and applying a magnetic field. For example, NiO (nickel oxide), which is used in the conductive connector 100 according to the first embodiment, is particularly preferred because it has a Neel temperature of 525 K, which is above 0°C. However, MnO (manganese oxide, with a Neel temperature of 116 K) can also be used.

[0106] Other than these, Cr ２ O ３ (chromium oxide), Mn ３ Ge, Mn ３ Sn, MnS, MnTe, MnF ２ , FeF ２ , FeCl ２ , FeO, CoCl ２, CoO, NiCl ２ Among these, MnTe (307K), FeO (298K), CoO (291K), and Cr (308K), which have Neel temperatures of 0°C or higher, are preferred because their antiferromagnetic properties can be easily utilized.

[0107] In addition to the carbonyl method used in the first embodiment, other known methods for producing the raw material of the approximately spherical particles 200 before antiferromagnetic treatment include the atomization method (a thin stream of molten metal or alloy is formed by flowing it out of a small hole in the bottom of a crucible, and high-speed air, nitrogen, argon, water, etc. is sprayed onto the stream to disperse the molten metal and rapidly cool and solidify it, thereby producing powder of the metal or alloy) and the electrolysis method (a raw material is electrolyzed to precipitate powder of the raw material on a cathode). However, according to experiments conducted by the present inventors, only the carbonyl method produced the desired good results. Therefore, it is preferable to produce the approximately spherical particles 200 before antiferromagnetic treatment using the carbonyl method.

[0108] Figure 3(a) is a diagram comparing the press-on load (when pressure is applied) for a conductive connector 100 using particles 200 made of metal Ni produced by the carbonyl method and the atomization method in an experiment conducted by the inventors, Figure 3(b) is a diagram showing an outline of the measurement probe used in the experiment, and Figure 3(c) is an external view of the measurement device used in the experiment. Figure 3(a) shows the load distribution when the resistance falls below 30 Ω, and the number of samples (n) is 10.

[0109] As can be seen from FIG. 3( a), the particles 200 using metal Ni (carbonyl nickel) produced by the carbonyl method have a significantly lower press-on load than the particles 200 using metal Ni (atomized nickel) produced by the atomization method. Specifically, the press-on load for carbonyl nickel is significantly lower than that for atomized nickel (1 / 10), demonstrating a significant difference between the two. When the press-on load for carbonyl nickel is converted to the press-on load for an electrode with a diameter of 0.04 mm, it corresponds to 0.013 times the press-on load for an electrode with a diameter of 0.35 mm, which indicates that the press-on load is in the mg range. This means that the conductive connector 100 according to the first embodiment using carbonyl nickel requires very little contact pressure (contact force) with the terminal 304 of the wafer 300.

[0110] The inventors believe that the reason for this difference in the PRESS-ON load is that the microparticles 202 formed using carbonyl nickel have minute protrusions (unevenness) on their surfaces and contain more defects (microvoids, distortion, lattice defects, impurities, etc.) inside than microparticles produced by methods other than the carbonyl method, such as atomization or electrolysis.

[0111] That is, in the microparticles 202 that form the particles 200 in which magnetic anisotropy and quantum effects have been manifested and established, the surfaces and interfaces are NiO, resulting in a topologically superconducting state, and it is presumed that the interior maintains the ferromagnetic state of Ni. Therefore, a portion of the magnetic flux of the external magnetic field applied in the antiferromagnetic treatment penetrates the surfaces and interfaces of the microparticles 202, which are in a topologically superconducting state. The protrusions (irregularities) and defects serve as escape routes for the magnetic flux that has thus penetrated the surfaces and interfaces of the microparticles 202, preventing the magnetic flux from moving away from the protrusions (irregularities) and defects. As a result, it is presumed that the magnetic flux is pinned to these escape routes, resulting in the manifestation of magnetic anisotropy in the microparticles 202.

[0112] Due to this magnetic anisotropy, the magnetization easy direction of the microparticles 202 (and particles 200) rotates in the direction of the magnetic flux and is fixed in that direction, so that the magnetization easy direction of the microparticles 202 (and particles 200) coincides with the direction of the magnetic flux.

[0113] Furthermore, in addition to the manifestation and fixation of the magnetic anisotropy described above, the antiferromagnetic treatment of the microparticles 202 (and particles 200) also manifests and fixes quantum effects (such as the generation of skyrmions, tunneling magnetoresistance, and current-spin current conversion). It is therefore presumed that this quantum effect causes a spin current with nearly zero spin current resistance to flow, or a current with very low current resistance, to flow in the conductive portion 114 of the single particle film 110 or the conductive portion 134 of the cluster film 130. This is also presumed to be the cause of the above-described difference in the PRESS-ON load. Details of this quantum effect and its action will be described later.

[0114] 4 and 8, a method for forming the single particle film (first anisotropic conductive film) 110 and the cluster film (second anisotropic conductive film) 130 used in the conductive connector 100 according to the first embodiment will be described. At this time, the magnetic anisotropy of the granular particles 202b (and the particles 200a) and the manifestation and establishment of the quantum effect will also be mentioned.

[0115] As shown in Figure 4(a), first, roughly spherical particles 200 with a diameter (median diameter) in the range of approximately 0.1 μm to 10 μm are added together with a binder to an uncured insulating polymer material prepared for the insulating thin film 112 that forms the monoparticle film (first anisotropic conductive film) 110, to prepare a raw material (see step S3 in Figure 17). Both the particles 200 and the microparticles 202 that form them are before the above-mentioned magnetic anisotropy is imparted and the quantum effect is expressed, and therefore do not possess magnetic anisotropy or quantum effect.

[0116] Next, a sheet-like cavity (not shown) inside the mold 500 is evacuated, and the raw material is then injected into the cavity. The mold 500 is equipped with a magnetic field generator 520, whose coil 522 generates a magnetic field that passes through its yoke 524 and applies the magnetic field to the cavity inside the mold 500. The magnetic field generator 520 generates a magnetic field, which is then applied to the raw material inside the cavity via the mold 500. At the same time, a heating device (not shown) heats the raw material inside the cavity to a predetermined heating temperature (e.g., 100°C). After a predetermined time has elapsed, both the application of the magnetic field and the heating are stopped, and the raw material is then left at room temperature for a further predetermined time to crosslink and harden. In this way, an insulating thin film 112 (i.e., a monoparticle film 110) is obtained, with particles 200 dispersed therein.

[0117] The application of the magnetic field and the heating cause the particles 200 (and the microparticles 202 that form them) in the raw material to exhibit the magnetic anisotropy and the quantum effect. Then, by leaving the raw material at room temperature with the application of the magnetic field and the heating stopped, the magnetic anisotropy and the quantum effect that have been exhibited in the particles 200 (and the microparticles 202 that form them) in the raw material are fixed (see steps S4 and S5 in FIG. 17).

[0118] Furthermore, the particles 200 in the raw material made of NiO and the microparticles 202 that form them are hardly oxidized by the heating. This is because much of the metallic Ni in the raw material is oxidized and converted into nickel oxide (NiO) when it is refined by the carbonyl method. However, it is presumed that not all of the metallic Ni is converted into nickel oxide (NiO) at this time, and that some of the Ni inside the microparticles 202 remains as it is, and therefore it is believed that there are ferromagnetic portions inside the microparticles 202.

[0119] The strength of the magnetic field and the heating temperature are set within a range in which the particles 200 in the raw material and the microparticles 202 that form them exhibit the magnetic anisotropy and the quantum effect as desired.

[0120] The method for forming the cluster film (second anisotropic conductive film) 130 is the same as the method for forming the monoparticle film 110 described above, except that the separated particles 200 forming a single particle layer are replaced with a cluster 210 of two (or three or more) overlapping particles 200. Therefore, the method for forming the insulating thin film 112 (the method for forming the monoparticle film 110) shown in Figures 4(a) and (b) can also be applied directly to the method for forming the insulating thin film 132 (the method for forming the cluster film 130) shown in Figures 4(a) and (c). Therefore, a description of the method for forming the insulating thin film 132 will be omitted.

[0121] The method for forming the insulating thin film 112 shown in Figures 4(a) and (b) (method for forming the single particle film 110) and the method for forming the insulating thin film 132 shown in Figures 4(a) and (c) (method for forming the cluster film 130) can also be performed using a film formation apparatus such as that shown in Figure 8(a).

[0122] The film-forming apparatus shown in FIG. 8( a) is configured to pour the raw material into a gap formed by upper and lower supports 540 and 542, which are arranged facing each other, to form the raw material into a sheet. The upper and lower supports 540 and 542 are rotated by rollers 530 and 532, respectively, and translated in the same direction (toward the right in FIG. 8 ). The raw material poured into the gap is sandwiched between the upper and lower supports 540 and 542 and translated across a horizontal plane, forming a sheet between them. During this process, a weak magnetic field generated by coil 522 of magnetic field generator 520 is applied to the raw material. The raw material is also heated to a predetermined temperature (e.g., 100°C) by a heating device (not shown). The application of the magnetic field and the heating (antiferromagnetic treatment) cause the particles 200 in the raw material and the microparticles 202 that form them to exhibit the magnetic anisotropy and quantum effect. This is the same as the film-forming apparatus shown in FIG. 4( a).

[0123] As shown in the right diagram of Figure 8, the raw material formed into a sheet is crosslinked and hardened by leaving it at room temperature without applying the magnetic field or heating. This allows the magnetic anisotropy and quantum effect expressed in the particles 200 in the raw material and the microparticles 202 that form them to become fixed. In this way, an insulating thin film 112 or 132 (i.e., a single particle film 110 or a cluster film 130) with the particles 200 dispersed therein is obtained. This is also the same film formation apparatus as that shown in Figure 4(a).

[0124] As mentioned above, the particles 200 in the raw material, which are made of metallic Ni, and the microparticles 202 that form them are not oxidized by the heating. The particles 200 in the raw material and the microparticles 202 that form them, which have the magnetic anisotropy and the quantum effect, are formed not from metallic Ni but from nickel oxide (NiO). However, it is presumed that not all of the metallic Ni is converted to nickel oxide (NiO), and that some of the Ni inside the microparticles 202 remains as is, so it is believed that there are ferromagnetic portions inside the microparticles 202. This is also the same as the film formation apparatus shown in FIG. 4( a). It goes without saying that the magnetic field strength and the heating temperature are also set within a range in which the particles 200 in the raw material (and the microparticles 202 that form them) exhibit the magnetic anisotropy and the quantum effect.

[0125] Next, the magnetic field applied to the cavity inside the mold 500 will be described with reference to FIGS. 10 and 11 and FIGS. 4(b) and (c).

[0126] According to the research of the present inventors, it has been found that the magnetic field is preferably a parallel magnetic field, and that there is a preferred range for the strength of the magnetic field. ２ Gauss ~ 10 ３ In other words, if the lower limit of the range is Hc1 and the upper limit is Hc2, the lower limit Hc1 is 10 ２ (=100) Gauss (GAUSS), upper limit Hc2 is 10 ３4(b) and (c) show that a parallel magnetic field within such a preferred range (i.e., between the lower limit Hc1 and the upper limit Hc2) is applied as the magnetic field.

[0127] As clearly shown in FIG. 10, in order to develop and establish the magnetic anisotropy of the particles 200 (and the microparticles 202 that form them) in the raw material, the strength of the magnetic field should be set to the lower limit Hc1 of the preferred range, i.e., 10 ２ It has been found that it is preferable to set the magnetic field strength at Hc1 (=100) gauss. In this case, all of the magnetic moments (micromagnets) of the granular particles 202b in the raw material are aligned in the direction of the magnetic flux of the magnetic field, and the inventors believe that this results in the highest degree of magnetic anisotropy being exhibited in the particles 200 (and the microparticles 202) in the raw material. The magnetic field strength is set to the lower limit Hc1 of the preferable range for a single particle film 110 in which only separated particles 200 exist inside the insulating thin film 112.

[0128] Therefore, the strength of the virtual magnetic field generated in the particles 200 (and the microparticles 202) in the raw material is at its highest level, and as a result, it is thought that it is possible to maximize the manifestation of quantum effects (such as the generation of skyrmions, tunnel magnetoresistance, and current-spin current conversion) that occur in the particles 200 (and the microparticles 202) in the raw material. In this case, as shown in Figure 11, the spin current resistance Rs is almost zero, and therefore electrical conduction with almost zero electrical resistance can be achieved in the conductive path 114 of the single particle film 110.

[0129] The strength of the magnetic field applied to the particles 200 (and the microparticles 202) in the raw material is set to the upper limit Hc2 of the preferred range, i.e., 10 ３(=1000) Gauss, the magnetic anisotropy of the particles 200 (and the microparticles 202 that form them) in the raw material is thought to be disrupted. This means that not all of the magnetic moments (micromagnets) of the microparticles 202 are aligned in the direction of the magnetic flux of the magnetic field, and some of the magnetic moments (micromagnets) are deviated from the direction of the magnetic flux of the magnetic field. As a result, the level of magnetic anisotropy is thought to be lower than when the magnetic field strength is set to the lower limit Hc1 of the preferred range. The magnetic field strength is set to the upper limit Hc2 of the preferred range for the cluster film 130 in which only separated particle clusters 210 exist inside the insulating thin film 132.

[0130] Therefore, the strength of the virtual magnetic field generated in the particles 200 (and the small particles 202) in the raw material is reduced below the maximum level described above. As a result, it is considered that the expression level of the quantum effect exhibited in the particles 200 (and the microparticles 202) in the raw material is also reduced below the maximum level described above. In this case, as shown in FIG. 11, the spin current resistance Rs is approximately zero, but the current resistance Re is a finite value exceeding zero, so the electrical resistance, which is the sum of the spin current resistance Rs and the current resistance Re, also becomes a finite value exceeding zero. Therefore, in the conductive paths 134 of the cluster film 130, electrical conduction can be achieved with electrical resistance suppressed to a low value exceeding zero.

[0131] The strength of the magnetic field applied to the particles 200 (and the microparticles 202) in the raw material is set to the upper limit Hc2 of the preferred range, i.e., 10 ３If the magnetic field strength is set higher than (=1000) gauss, the magnetic anisotropy of the particles 200 (and microparticles 202) in the raw material will be completely destroyed, and the magnetization of the particles 200 (and microparticles 202) will be saturated. This means that not all of the magnetic moments (micromagnets) of the microparticles 202 are aligned in the direction of the magnetic flux of the magnetic field. As a result, the level of magnetic anisotropy will be significantly reduced compared to when the magnetic field strength is set at the lower limit Hc1 of the preferred range, to a level that can be considered nonexistent. Setting the magnetic field strength to a value exceeding the upper limit Hc2 of the preferred range will result in a film (not shown) in which only non-separated particle clusters 210 exist within the insulating thin film.

[0132] Therefore, the strength of the virtual magnetic field generated in the particles 200 (microparticles 202) in the raw material is significantly lower than the maximum level described above. As a result, the level of quantum effect manifested in the particles 200 (and microparticles 202) in the raw material is also significantly lower than the maximum level described above, to the point where it can be said that quantum effect is not manifested at all. In this case, as shown in Figure 11, the electrical resistance becomes even higher, and electrical conduction with low electrical resistance cannot be achieved.

[0133] Next, the relationship between the thickness of the insulating thin films 112 and 132 of the single particle film 110 and the cluster film 130 and the size (diameter) of the particles 200 will be described.

[0134] The monoparticle film 110 has a configuration in which the particles 200 in a separated state are dispersed and arranged within the insulating thin film 112 so as to form a single layer in the in-plane direction of the insulating thin film 112. To achieve this, the thickness of the insulating thin film 112 is set to be less than twice the median diameter of the particles 200. This prevents the particles 200 (and the microparticles 202) in the raw material from agglomerating in the thickness direction of the insulating thin film 112 during the formation of the insulating thin film 112, and maintains their separated state. As a result, the particles 200 are reliably dispersed and arranged as a single particle layer within the insulating thin film 112 during the film formation process, as shown in FIG. 1( b). This reliably prevents the formed monoparticle film 110 (insulating thin film 112) from becoming conductive in the in-plane direction, i.e., prevents two adjacent conductive portions 114 from becoming electrically conductive.

[0135] Furthermore, due to the magnetic field applied during film formation, the direction of easy magnetization of the particles 200 (and microparticles 202) in the raw material is aligned with the direction of the magnetic flux of the magnetic field, i.e., the thickness direction of the insulating thin film 112, as shown in Figure 4 (b), so that the particles 200 (and microparticles 202) in the raw material exhibit the desired magnetic anisotropy.

[0136] The cluster film 130 has a configuration in which the particles 200 dispersed within the insulating thin film 132 aggregate and form rows in the thickness direction of the insulating thin film 132. To achieve this, the thickness of the insulating thin film 132 is set to be at least twice the median diameter of the particles 200. As a result, during the formation of the insulating thin film 132, the particles 200 (and the microparticles 202) in the raw material are reliably dispersed and arranged as a single cluster layer within the insulating thin film 132, as shown in FIG. 1( b), in the same manner as the separated particles 200 arranged within the insulating thin film 112 of the single-particle film 110. This reliably prevents the formed cluster film 130 (insulating thin film 132) from becoming conductive in the in-plane direction, i.e., prevents two adjacent conductive portions 134 from becoming electrically conductive.

[0137] Furthermore, as shown in Figure 4(c), the magnetic field applied during film formation causes the magnetic moments (micromagnets) of the particles 200 (and microparticles 202) in the raw material to align in the direction of the magnetic flux of the magnetic field, i.e., in the thickness direction of the insulating thin film 132, so that the particles 200 (and microparticles 202) in the raw material exhibit the desired magnetic anisotropy.

[0138] An electron microscope photograph showing a specific example of particle 200 actually produced by the present inventors is shown in Figure 2(c). The particle 200 in Figure 2(c) has a diameter of 2 to 3 μm, and it can be seen that protrusions (concave and convex) 204 are formed on its surface. The height difference of the protrusions (concave and convex) 204 is within the range of approximately 10 nm to 100 nm.

[0139] Next, in order to evaluate the performance of the conductive connector 100 according to the first embodiment of the present invention described above, a comparative test of various performances was conducted on a probe manufactured using the conductive connector 100 and the probes of Comparative Examples 1 and 2. The results will be described with reference to Figure 5.

[0140] The probe of Comparative Example 1 used in the above test used a metal terminal as a conductive connector. The metal terminal was made of spring-elastic tungsten or phosphor bronze and was formed from a metal wire (bending wire) that was given a curvature to make it easy to bend.

[0141] The probe of Comparative Example 2 used in the above test uses PCR (pressure conductive rubber). The PCR is formed by dispersing nickel particles plated with gold or silver in a silicone rubber sheet. The plated nickel particles have a magnetic field strength above the upper limit Hc2 of the preferred range for the magnetic field strength mentioned above, i.e., 10 ３ The particles are aggregated and magnetized by applying a strong magnetic field exceeding (=1000) gauss, which aims to suppress an increase in the electrical resistance of the PCR.

[0142] Regarding the electrical resistance in Figure 5, which shows the results of the above test, the metal probe of Comparative Example 1 exhibited the current resistance of the metal material used in the metal probe. The PCR of Comparative Example 2 exhibited lower current resistance than the metal probe of Comparative Example 1. In contrast, the conductive connector 100 according to the present invention exhibited almost no current resistance, and the spin current resistance was approximately 0 mΩ. This means that the conductive connector 100 has a low resistance equivalent to that of a superconductor, and it is therefore inferred that the conductive connector 100 has electrical conductivity utilizing current-spin current conversion based on the quantum effect.

[0143] Contact resistance was not measured in Comparative Examples 1 and 2. However, in the conductive connector 100 according to the present invention, an electrical resistance of 0 mΩ means that the contact resistance is also 0 mΩ. Even when a high current was tested (continuous current was applied for 30 seconds), the measurement wiring heated up, but no heat generation was observed in the conductive connector 100.

[0144] The contact force in Figure 5 refers to the pressure required to conduct electricity. The contact force was 10 g / pin for the metal probe of Comparative Example 1 and 1 to 10 g / pin for the PCR of Comparative Example 2, while the contact force was 1 to 10 mg / pin for the conductive connector 100 according to the present invention. In other words, the conductive connector 100 according to the present invention can achieve conductivity even when the load (contact force) applied to each pin is significantly lower than those of Comparative Examples 1 and 2. This is thought to be because, in the conductive connector 100, the spin current conducts through a tunnel barrier. In other words, it is presumed that stable contact is achieved by utilizing a stable tunnel barrier (approximately 1 to 20 nm thick) such as an oxide film on the surface of the contact object.

[0145] Regarding the contact stability (MTBF; mean time between failures) in FIG. 5, Comparative Example 1 was 10 ４ (10,000) times or less, and 10 ４～６ (10,000 to 1,000,000) times or less, whereas the conductive connector 100 according to the present invention ８(100,000,000) times or more. Furthermore, in order to maintain contact stability, in Comparative Example 1, scrubbing (scratching the surface to remove oxide films, etc.) and removal of tunnel barriers that inhibit contact by current by washing and cleaning were required. In Comparative Example 2, scrubbing was not necessary, but cleaning was. In the conductive connector 100 according to the present invention, neither scrubbing nor cleaning was required.

[0146] 5, in Comparative Example 1, the size was approximately 80 μm due to manufacturing reasons. In Comparative Example 2, the size was approximately 200 μm due to the limitations of PCR particle clustering (aggregation and lateral conduction). In contrast, in the conductive connector 100 according to the present invention, the single particle film 110 could be miniaturized to approximately 0.1 to 10 μm, which is the particle size of the particle 200.

[0147] 5, the upper limit of the number of pins that can be tested at one time with the metal probe of Comparative Example 1 was 10,000 (10,000) at most due to contact stability, whereas the conductive connector 100 according to the present invention was capable of simultaneous contact with 1,000,000 (1,000,000) terminals. This is presumably due to the fact that the contact force per pin of the conductive connector 100 is significantly lower, allowing the tunneling effect to be stably maintained by preserving the tunnel barrier non-destructively, and that the conductive connector 100 is configured as a sheet laminate type that can be miniaturized. However, it is believed that the upper limit of the number of pins in the conductive connector 100 varies depending on the MTBF.

[0148] (Operation of the Conductive Connector 100 According to the First Embodiment of the Present Invention) Next, the operation of the conductive connector 100 having the above-described configuration will be described.

[0149] As is clear from the above explanation made with reference to Figure 5 showing the results of the performance comparison test, the conductive connector 100 according to the first embodiment of the present invention has low electrical resistance and contact resistance of 0 mΩ. The configuration and conditions for achieving this will be explained below, but it should be noted in advance that this includes some speculation by the inventors (including matters that are difficult to confirm).

[0150] In the conductive connector 100 having the above-described configuration, the conductive portion 114 of the single particle film (first anisotropic conductive film) 110 and the conductive portion 134 of the cluster film (second anisotropic conductive film) 130 are formed by particles 200 (and the microparticles 202 that form them). Therefore, the first reason why the electrical resistance and contact resistance are so low as to show almost 0 mΩ is that, due to the magnetic anisotropy and quantum effect of the particles 200 (and the microparticles 202) made of NiO that exhibit topological antiferromagnetic properties, the surfaces and interfaces of the particles 200 that form the conductive portions 114 and 134 are in a topological superconducting state, as shown in the right diagram of Figure 9. Spin current and electric current flow through these surfaces and interfaces, so the electrical resistance (which is expressed as the sum of the electric current resistance and the spin current resistance) of each of the conductive portions 114 and 134 is zero.

[0151] The second reason why the electrical resistance and contact resistance are so low as to show almost 0 mΩ is that the conductive portion 114 of the single particle film (first anisotropic conductive film) 110 and the conductive portion 134 of the cluster film (second anisotropic conductive film) 130 are formed by particles 200. Therefore, due to the magnetic anisotropy and quantum effect of the particles 200 (and the microparticles 202), inside each of the conductive portions 114 and 134, as shown in Figure 14, (a) multiple spin flow path candidates 606 are formed connecting the south pole region 604 and the north pole region 602 at the end of the particle 200 in the easy direction of magnetization, (b) a tunnel magnetoresistance effect occurs in the south pole region 604 and the north pole region 602 of the particle 200, and (c) electric current-spin current conversion occurs in the south pole region 604 and the north pole region 602 of the particle 200. Due to these three factors, as shown in FIG. 13 , a “spin current” flows between the south pole region 604 and the north pole region 602 of the particle 200 made of NiO, which is an insulator, and an “electric current” flows in the areas outside the south pole region 604 and the north pole region 602. Furthermore, since the “electric current” and the “spin current” can be mutually converted, electrical conduction is realized inside each of the conductive parts 114 and 134.

[0152] 14, skyrmions are generated in a concentrated manner in the south pole region 604 and north pole region 602 of the particle 200. In other words, skyrmion-concentrated regions are formed in the south pole region 604 and north pole region 602, respectively. Then, due to the action of the skyrmions present in the skyrmion-concentrated regions, a "tunnel magnetoresistance effect" and "electric current-spin current conversion" occur in the south pole region 604 and north pole region 602.

[0153] Here, a skyrmion is a topological vortex-like magnetic structure formed by electron spins in a solid (magnetic material). The central and peripheral spins of a skyrmion are antiparallel, and the spins between them are arranged in a vortex shape, gradually changing direction. The diameter of the vortex is tens to hundreds of nanometers. When a skyrmion is generated, the magnetic flux density at the generation site is amplified tens of thousands of times, thereby significantly increasing the magnetic field strength at the generation site. This significantly increases the magnetic field strength in the skyrmion-concentrated region, which is thought to maximize the quantum effect described above. Since each skyrmion can be considered a microscopic magnet, a repulsive force acts between adjacent skyrmions. Therefore, as shown in Figure 14, a spin flow path candidate 606 consisting of skyrmions is generated in a spherically bulging shape between the south pole region 604 and the north pole region 602.

[0154] Furthermore, skyrmions are generated along the magnetic flux of the external magnetic field that penetrates into the particle 200 and is pinned so as to connect the south pole region 604 and the north pole region 602 of the particle 200. Then, due to the action of these skyrmions, a conduction path for spin current is formed along the magnetic flux that connects the south pole region 604 and the north pole region 602.

[0155] Due to the above-mentioned "tunnel magnetoresistance effect," as shown in Figure 12 (a), electrical conduction is achieved in each of the conductive portions 114 and 134 by penetrating the insulating film, such as an oxide film, of the particle 200 without destroying the insulating film.

[0156] Furthermore, the above-mentioned "electric current-spin current conversion" makes it possible to convert between a "spin current" that electrically connects the south pole region 604 and the north pole region 602 of the particle 200 and a "electric current" that electrically connects other parts, via a spin current conducting path that interconnects the south pole region 604 and the north pole region 602 of the particle 200.

[0157] In this way, as shown in FIG. 13, in each of the conductive portions 114 and 134 made of particles 200, electrical conduction can be achieved while suppressing the electrical resistance and contact resistance to such a low level that they exhibit almost 0 mΩ.

[0158] In the conductive connector 100, as described above, a topological superconducting state occurs at the surfaces and interfaces of the particles 200 that form the conductive portions 114 and 134. In addition, (a) a spin current conduction path is formed connecting the south pole region 604 and the north pole region 602 at the end of the easy direction of magnetization of the particle 200, (b) a tunnel magnetoresistance effect occurs between the south pole region 604 and the north pole region 602 of the particle 200, and (c) current-spin current conversion occurs between the south pole region 604 and the north pole region 602 of the particle 200, thereby providing electrical conductivity to the conductive portions 114 and 134. Therefore, even with a minute contact point with a diameter of 40 μm, and even when a high current of 3 A was passed three times for several tens of seconds, no change in the heat generation state occurred. This is presumably due to the realization of these four factors.

[0159] 12(b) and 15, spin current has a feature called "exclusive spin current conduction path switching," in which the one with the lowest spin current resistance is instantly found and switched from among multiple spin current path candidates 606 existing between a pair of electrodes. It is inferred that this feature tends to reduce the electrical resistance of each of the conduction parts 114 and 134 when electrical conduction between the conduction parts 114 and 134 is achieved by utilizing the above-mentioned magnetic anisotropy and quantum effect of the particle 200.

[0160] The spin current path candidate 606 used in the "exclusive spin current path switching" is understood to be the path of magnetic flux of an external magnetic field existing inside the particle 200. Because the particle 200 is an aggregate of microparticles 202, it has many interfaces (defects and surfaces) between the microparticles 202, and these interfaces serve as spin current paths. Defects (microvoids, strains (lattice defects), impurities) existing inside the microparticles 202 due to the carbonyl process, gaps between the microparticles 202 existing inside the particle 200, and interfaces (surfaces) between the particles 200 and the microparticles 202 also serve as spin current path candidate 606. One of these numerous spin current path candidate 606 is selected depending on the type of applied electrical signal, such as direct current or high frequency, and spin current flows through it. Needless to say, as can be seen from FIG. 11 , electric current may also flow through the spin current path candidate 606 along with the spin current.

[0161] FIG. 16 shows the relationship between the size (diameter) of the conductive portions 114 and 134 of the anisotropic conductive film (single particle film, cluster film) used in the conductive connector 100 according to the first embodiment and the generation status of the spin flow path candidates 606 formed in the conductive portions 114 and 134.

[0162] 16, due to the above-mentioned feature of "exclusive spin current conductive path switching," the spin current flowing through the voltage-driven circuit is automatically switched instantly to the conductive path with the lowest spin current resistance (which is approximately 0 Ω). Therefore, it is clear that the conductive connector 100 having this feature can be easily further miniaturized.

[0163] The specific dimensions of each part of the conductive connector 100 having the above configuration are determined so as to match the arrangement of the terminals 304 on the wafer 300 and the electrodes 404 on the test head 400 .

[0164] The vortex structure formed when a magnetic field penetrates a type-II superconductor is called a "superconducting vortex." Recently, it has been revealed that this "superconducting vortex" coexists with a "skyrmion," a topological spin structure that appears in magnetic materials. That is, as shown in FIG. 9, when the interface between the surface layer and the interior of the microparticle 202 is in a topological superconducting state, skyrmions exist at the interface with the surface layer in a superconducting state, meaning that the two coexist. This demonstrates that the explanation given above regarding the operation of the conductive connector 100 is scientifically valid.

[0165] 14, since the skyrmions are generated in a concentrated manner in the south pole region 604 and the north pole region 602 of the particle 200, the density of the spin flow path candidate 606 is also concentrated in these two regions 604, 602. Therefore, the density of the spin flow path candidate 606 in the south pole region 604 and the north pole region 602 is 10 times lower than the density of the spin flow path candidate 606 near the central nucleus of the particle 200. ６ This means that the area of ​​the cross section near the central core of the particle 200 is 10 times larger than the area of ​​each of the south polar region 604 and the north polar region 602. ６ This is because the spin flow path candidate 606 exists at a high density in each of the south pole region 604 and the north pole region 602, and the protrusions (concaves and recesses) 204 that contribute to the generation of the spin flow path candidate 606 exist on the surface of the approximately spherical particle 200. Therefore, the selection efficiency of the spin flow path candidate 606 when current is applied is improved, and the MTBF during repeated contact is also maximized (MTBF≧10 ８ ) is presumed to be the case.

[0166] (Conductive Connector 100A According to a Second Embodiment of the Present Invention) FIG. 19 is a schematic cross-sectional view showing the configuration of a conductive connector 100A according to a second embodiment of the present invention.

[0167] As shown in Figure 19, the conductive connector 100A uses four anisotropic conductive films, each of which is the same as the conductive connector 100 according to the first embodiment described above. That is, a single particle film 110 is disposed as the bottom layer (first layer), a layer of a movable electrode 210 is disposed on top of that as the second layer, and a cluster film 130 is disposed on top of that as the third layer. The configuration up to this point is the same as that of the conductive connector 100 according to the first embodiment described above.

[0168] A layer of movable electrode 210 is placed on top of cluster film 130 as the third layer, and another layer of cluster film 130 is placed on top of that as the fifth layer, and another layer of movable electrode 210 is placed on top of that as the sixth layer, and another layer of cluster film 130 is placed on top of that as the seventh layer.

[0169] The conductive connector 100A according to the second embodiment uses a total of four anisotropic conductive films 110 and 130, which has the advantage of being able to further reduce the amount of displacement of the anisotropic conductive film in each layer compared to the conductive connector 100 of the first embodiment, which uses a total of two anisotropic conductive films. This reduces the contact pressure between the anisotropic conductive film in each layer and the terminals 304 and electrodes 404, and also makes it possible to increase the durability of the conductive connector 100.

[0170] Incidentally, a configuration in which an insulating layer is provided on the surface layer of conductive particles in an anisotropic conductive film has been proposed. For example, the above-mentioned Patent Document 2 (Japanese Patent No. 5476221) describes a configuration in which a nickel conductive layer is provided on the surface layer of a base particle (resin), and a nickel oxide or nickel hydroxide coating is provided on the outer surface. Furthermore, the above-mentioned Patent Document 3 (Japanese Patent Laid-Open No. 2021-064591) and Patent Document 4 (Japanese Patent Laid-Open No. 2022-041178) also propose coated particles in which conductive particles are coated with an insulating layer.

[0171] However, these documents assume that applying a high load to an anisotropic conductive film will break the oxide film, thereby connecting the conductive layers and achieving electrical continuity (i.e., electronic conduction is intended). This conventional conduction method does not allow stable spin-current-to-electric current conversion. Unless the conductive layers are configured to contact each other with a low load, it is impossible to achieve the coexistence of highly efficient spin-current-to-electric current conversion and topological superconductivity, as in the present invention. However, since the conventional configuration required the application of a high load to simultaneously connect multiple electrodes, the method of breaking the oxide film did not pose any problems.

[0172] In contrast, in the configuration of the conductive connectors 100 and 100A according to the present invention, the single particle film 110 and the cluster film 130 are flexible in the thickness direction, and the cluster film 130 is flexible in the thickness direction, making it possible to absorb minute irregularities in the terminals 304 of the wafer 300 and the electrodes 404 of the test head 400. Furthermore, because the movable electrode 120 (coin tablet type) does not have a support film (holding film), there is nothing to hinder the movement of the movable electrode 120 in the thickness direction. These factors improve contact stability at low loads. Furthermore, because the particles 200 exhibiting topological antiferromagnetic properties contact the circuits 302 of the wafer 300 and the electrodes 404 of the test head 400 with an extremely small area at low loads, probes for semiconductor testing devices can be further miniaturized.

[0173] (Modifications) Finally, possible modifications of the first and second embodiments will be described.

[0174] In the first and second embodiments described above, the particles 200 made of an insulating topological antiferromagnetic material are manufactured using NiO obtained by oxidizing metallic Ni obtained using the carbonyl method. However, this NiO may be single-crystal NiO alone or a polycrystalline body of Ni and NiOx. Manganese (Mn) can also be used instead of Ni. In this case, as in the case of using NiO, the particles 200 can be manufactured using MnO obtained by oxidizing metallic Mn obtained using the carbonyl method. There are several types of MnO with different oxidation numbers, and any of them can be used. This MnO may be single-crystal MnO alone or a polycrystalline body of Mn and MnOx.

[0175] In addition to NiO and MnO, Cr ２ O ３ , Mn ３ Ge, Mn ３ Sn, MnS, MnTe, MnF ２ , FeF ２ , FeCl ２ , FeO, CoCl ２ , CoO, NiCl ２ , NiO, and Cr can be used.

[0176] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited thereto. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention.

[0177] The present invention can be suitably used in cases where it is necessary to electrically connect a large number of electrodes (e.g., hundreds to tens of thousands) of electrodes under test at once (e.g., wafer probes of semiconductor test equipment used in wafer testing).

[0178] 100, 100A Conductive connector 110 Single particle film 112 Insulating thin film 114 Conductive portion 120 Movable electrode 130 Cluster film 132 Insulating thin film 134 Conductive portion 200 Particle 202 Microparticle 204 Protrusion (unevenness) on particle surface 300 Wafer 302 Circuit 304 Terminal 400 Test head 404 Electrode 500 Mold 520 Magnetic field generator 522 Coil 530, 532 Roller 540 Upper support 542 Lower support 602 North pole region of particle 604 South pole region of particle 606 Candidate for spin flow path

Claims

1. An insulating thin film made of an elastic insulating polymer material, The insulating thin film contains a plurality of substantially spherical particles made of a material exhibiting topological antiferromagnetic properties, The plurality of particles are arranged within the insulating thin film at a distance from each other in the in-plane direction, so as not to cause electrical conductivity in the in-plane direction of the insulating thin film, and form a plurality of conductive portions that enable electrical conductivity in the thickness direction of the insulating thin film. Each of the plurality of particles has magnetic anisotropy, and its easy magnetization direction is oriented in the thickness direction of the insulating thin film. Each of the plurality of particles has an antarctic region and an anode region formed at two ends in the direction along the easy magnetization direction, and the magnetic flux of the virtual magnetic field is concentrated in the antarctic region and the anode region, and moreover, it has a plurality of candidate spin current paths connecting the antarctic region and the anode region. During operation, a voltage is applied between the Antarctic region and the Arctic region along the direction of easy magnetization, thereby, (a) The interior of each of the plurality of particles becomes superconducting, (b) In the region between the Antarctic region and the Arctic region, a spin current flows through one of the multiple candidate spin current pathways, (c) In the portion of the particle from the outside to the Antarctic region and in the portion of the particle from the outside to the Arctic region, (d) Current-spin current conversion occurs in the Antarctic region and the Arctic region, An anisotropic conductive film characterized in that electrical conductivity in the thickness direction of the insulating thin film is achieved through the conductive portion.

2. Each of the multiple conductive portions is formed from a single particle, The anisotropic conductive film according to claim 1, wherein the diameter of the particles is set to be greater than the thickness of the insulating thin film such that the ends of the particles protrude from both sides of the insulating thin film when the insulating thin film is not deformed by pressure.

3. Each of the multiple conductive portions is formed from a single cluster consisting of multiple particles arranged in parallel in the thickness direction of the insulating thin film. The anisotropic conductive film according to claim 1, wherein the length of the insulating thin film of the cluster in the thickness direction is set to be greater than the thickness of the insulating thin film such that the edges of the particles are exposed on both sides of the insulating thin film when the insulating thin film is not deformed by pressure.

4. The anisotropic conductive film according to claim 1, wherein the insulating thin film is in the form of a sheet that does not stretch or contract substantially in the in-plane direction and is flexible in the thickness direction.

5. The anisotropic conductive film according to any one of claims 1 to 4, wherein the topological antiferromagnetic material forming the particles is NiO (nickel oxide) or MnO (manganese oxide).

6. The aforementioned particles are substantially spherical particles with a diameter in the range of approximately 0.1 μm to 10 μm, formed by aggregating minute particles made of a material exhibiting topological antiferromagnetic properties. The anisotropic conductive film according to claim 1, wherein the surface of the substantially spherical particles has minute protrusions formed by the minute particles, the height difference being within the range of approximately 10 nm to 100 nm.

7. The anisotropic conductive film according to claim 1, wherein the thickness of the insulating thin film is less than twice the median diameter of the particles.

8. The anisotropic conductive film according to claim 1, wherein the magnetic anisotropy of the particles is imparted by applying a magnetic field of a strength within the range from a critical magnetic field Hc1 at which the applied magnetic field begins to penetrate into the interior of the particles during the formation of the insulating thin film, to a critical magnetic field Hc2 at which the magnetization saturates in the direction of the magnetic field and the direction of magnetization begins to become disordered.

9. A conductive connector for an inspection device, which transmits and receives electrical signals between the object to be inspected and the inspection device while in contact with multiple terminals of the object to be inspected, A first anisotropic conductive film formed by an anisotropic conductive film according to any one of claims 1 to 8, A second anisotropic conductive film formed by an anisotropic conductive film according to any one of claims 1 to 8, which is laminated on the first anisotropic conductive film, The device comprises a plurality of movable electrodes, which are movable in the stacking direction of the second anisotropic conductive film and are disposed between the first anisotropic conductive film and the second anisotropic conductive film, Each of the aforementioned movable electrodes is positioned to align with the positions of the aforementioned terminals. A conductive connector characterized by the following features.

10. Each of the aforementioned multiple movable electrodes is formed from a rigid material that is roughly disc-shaped. The plurality of movable electrodes are movable between the first anisotropic conductive film and the second anisotropic conductive film without using a retaining layer. The conductive connector according to claim 9, wherein when pressure is applied in the stacking direction while sandwiched between the object to be inspected and the inspection device, each of the plurality of movable electrodes is configured to contact and become electrically connected to one or more corresponding conductive portions of the first anisotropic conductive film, and to contact and become electrically connected to one or more corresponding conductive portions of the second anisotropic conductive film.

11. The plurality of movable electrodes further comprises a third anisotropic conductive film laminated on the first anisotropic conductive film and the second anisotropic conductive film on either the side of the first anisotropic conductive film or the side of the second anisotropic conductive film of the plurality of movable electrodes, The conductive connector according to claim 9 or 10, wherein the third anisotropic conductive film is formed by the anisotropic conductive film described in any one of claims 1 to 8.

12. A conductive structure that can be used as a conductive part of an anisotropic conductive film, It contains at least one substantially spherical particle formed from a material exhibiting topological antiferromagnetic properties, The aforementioned particle has magnetic anisotropy and has an antarctic region and an aortic region formed at two ends in the direction along its easy magnetization direction, When a voltage is applied between the Antarctic region and the Arctic region, (a) The surface and interface of the particles become topologically superconducting, (b) A spin current flows in the region between the Antarctic region and the Arctic region, (c) In the portion of the particle from the outside to the Antarctic region and in the portion of the particle from the outside to the Arctic region, (d) Current-spin current conversion occurs in the Antarctic region and the Arctic region, A conductive structure characterized in that electrical conductivity is achieved through the aforementioned particles.

13. The conductive structure according to claim 12, wherein the material exhibiting topological antiferromagnetic properties that forms the particles is NiO (nickel oxide) or MnO (manganese oxide).

14. The aforementioned particles are formed by aggregating minute particles made of a material exhibiting the topological antiferromagnetic properties into a substantially spherical shape. The diameter of the aforementioned particles is within the range of 0.1 μm to 10 μm. The conductive structure according to claim 12 or 13, wherein the surface of the particles has microprotrusions formed by the microparticles, the height difference being in the range of approximately 10 nm to 100 nm.

15. The conductive structure according to claim 14, wherein the magnetic anisotropy of the particles is imparted by applying a magnetic field of a strength within the range from a critical magnetic field Hc1 at which the applied magnetic field begins to penetrate into the interior of the particles during the formation of an insulating thin film, to a critical magnetic field Hc2 at which the magnetization saturates in the direction of the magnetic field and the direction of magnetization begins to become disordered.

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