JP2010258980A - Magnetic coupling type isolator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic coupling type isolator capable of sufficiently securing resistance against an external magnetic field and EMS. <P>SOLUTION: This magnetic coupling type isolator includes: a coil 2 for generating an external magnetic field by an input signal; magnetoresistive elements R1-R4 for detecting the external magnetic field and converting the detected magnetic field into an electric signal, the magnetoresistive elements being electrically insulated from the coil 2 and each disposed in a location capable of being magnetically coupled to overlap the coil 2 in a plan view; an upper shield film 41 and a lower shield film 42 disposed to overlap the coil 2 and the magnetoresistive elements R1-R4 in a plan view; and a middle shield film 43 disposed to surround the magnetoresistive elements R1-R4; wherein the upper shield film 41 and/or the lower shield film 42 have/has thickness of 0.5-15 μm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetically coupled isolator including a magnetic field generator and a magnetoresistive effect element (TMR element, CIP-GMR element, CPP-GMR element).

  In an electronic circuit, for example, if a portion where a large current flows and a portion where signal transmission is performed are close to each other, the large current may affect signal transmission. For this reason, a circuit element that electrically separates a portion where a large current flows in an electronic circuit from a portion where signal transmission is performed is required. As such an element, there is an optical isolator using a photocoupler. This optical isolator is composed of a combination of a light receiving element and a light emitting element, and is a circuit element having a function of converting a signal from electricity to light and then converting the light to electricity to transmit a signal.

  On the other hand, magnetically coupled isolators have been developed that can achieve smaller size and lower power consumption than optical isolators. For example, Patent Document 1 and Patent Document 2 disclose a magnetic field generating unit for converting an input signal into magnetism, and a magnetoresistive effect for detecting an external magnetic field generated from the magnetic field generating unit and converting it into an electric signal. A magnetically coupled isolator having an element is disclosed. Here, as the magnetoresistive effect element, a Hall element, an AMR element (anisotropic magnetoresistive effect element), or a GMR element (giant magnetoresistive effect element) is used.

  In the magnetically coupled isolators disclosed in Patent Documents 1 and 2, a shield film is provided on the upper part of the coil that is a magnetism generating portion, thereby exerting a shielding function against an unnecessary magnetic field from the external environment. This shield film also has a concentrator function of a magnetic field applied from the coil to the magnetoresistive element.

JP 2000-516714 Japanese translation of PCT publication No. 2003-526083

  However, the magnetically coupled isolators disclosed in Patent Documents 1 and 2 have a shield film disposed only on the top of the coil. Therefore, there is a problem that sufficient resistance against an external magnetic field or EMS (Electro Magnetic Susceptibility) cannot be secured.

  This invention is made | formed in view of this point, and it aims at providing the magnetic coupling type isolator which can fully ensure the tolerance with respect to an external magnetic field or EMS.

  The magnetically coupled isolator according to the present invention includes a magnetic field generator for generating an external magnetic field by an input signal, a position that is electrically insulated from the magnetic field generator and can be magnetically coupled. A magnetoresistive effect element that is disposed so as to overlap the magnetic field generation unit and detects the external magnetic field and converts it into an electric signal, and so as to overlap the magnetic field generation unit and the magnetoresistive effect element in plan view A first shield film and a second shield film disposed; and a third shield film disposed so as to surround the magnetoresistive element; and the first shield film and / or the second shield film. Has a thickness of 0.5 μm to 15 μm.

  According to this configuration, the first shield film and the second shield film having a predetermined thickness, which are disposed so as to overlap the magnetic field generation unit and the magnetoresistive effect element in plan view, are disposed so as to surround the magnetoresistive effect element. Since the third shield film is provided, sufficient resistance to an external magnetic field and EMS can be ensured.

  In the magnetically coupled isolator of the present invention, it is preferable that the first shield film, the second shield film, and / or the third shield film have a thickness of 0.5 μm to 10 μm. According to this configuration, it is possible to exhibit the shielding effect while exhibiting the enhancement effect of the magnetic field of the magnetic field generation unit.

  In the magnetically coupled isolator according to the present invention, the magnetic field generation unit includes a first magnetic field generation unit and a second magnetic field generation unit that generate external magnetic fields in opposite directions, and the first magnetic field generation unit And the magnetoresistive effect element arranged opposite to the second magnetic field generation unit, and each magnetoresistive effect element has the same layer configuration, and the first magnetic field It is preferable that the magnetoresistive effect element arranged to face the generating part and the magnetoresistive effect element arranged to face the second magnetic field generating part constitute a bridge circuit.

  In the magnetically coupled isolator according to the present invention, it is preferable that the first shield film has a function of enhancing a magnetic field applied to the bridge circuit from the magnetic field generator.

  In the magnetically coupled isolator of the present invention, it is preferable that the first shield film, the second shield film, and / or the third shield film are made of a high magnetic permeability material.

  In the magnetically coupled isolator according to the present invention, the first shield film, the second shield film, and / or the third shield film have a point-symmetric shape in plan view, and the center of each symmetry is It is preferable that they match.

  The magnetically coupled isolator according to the present invention includes a magnetic field generator for generating an external magnetic field by an input signal, a position that is electrically insulated from the magnetic field generator and can be magnetically coupled. A magnetoresistive effect element that is disposed so as to overlap the magnetic field generation unit and detects the external magnetic field and converts it into an electric signal, and so as to overlap the magnetic field generation unit and the magnetoresistive effect element in plan view A first shield film and a second shield film disposed; and a third shield film disposed so as to surround the magnetoresistive element; and the first shield film and / or the second shield film. Since it has a thickness of 0.5 μm to 15 μm, sufficient resistance to an external magnetic field and EMS can be ensured.

1 is an overall circuit configuration diagram of a magnetically coupled isolator according to an embodiment of the present invention. It is a bridge circuit figure comprised by magnetoresistive effect element R1-R4. It is a fragmentary top view which shows the magnetic coupling type isolator in the embodiment of this invention. It is the fragmentary sectional view cut | disconnected in the thickness direction along the AA line shown in FIG. 3, and was seen from the arrow direction. It is a fragmentary sectional view of the magnetic coupling type isolator which concerns on embodiment of this invention. It is a fragmentary sectional view of a TMR element which constitutes a magnetic coupling type isolator concerning an embodiment of the invention. It is a figure which shows the relationship between the thickness of the shielding film in a magnetic coupling type isolator, and the ratio of the magnetic field applied to a magnetoresistive effect element at the time of applying an external magnetic field. It is a figure which shows the relationship between the thickness of the shielding film in a magnetic coupling type isolator, and the ratio of the magnetic field applied to a magnetoresistive effect element at the time of applying an external magnetic field. It is a figure which shows the relationship between the thickness of the shielding film in a magnetic coupling type isolator, and the ratio of the magnetic field applied to a magnetoresistive effect element at the time of applying an external magnetic field. It is a figure which shows the relationship between the thickness of the shield film in a magnetic coupling type isolator, and the magnetic field applied to a magnetoresistive effect element from a coil.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
1 is an overall circuit configuration diagram of a magnetically coupled isolator (magnetic coupler) according to the present embodiment, and FIG. 2 is a bridge circuit diagram including magnetoresistive effect elements R1 to R4. These are the fragmentary top views of the magnetic coupling type isolator in this Embodiment, and FIG. 4 is the fragmentary sectional view cut | disconnected in the thickness direction along the AA line shown in FIG. In FIG. 3, the insulating layer is not shown, only the inner edge and the outer edge of the coil 2 are shown, and the magnetoresistive elements R <b> 1 to R <b> 4 positioned below the coil 2 are shown through.

  As shown in FIG. 1, a magnetically coupled isolator 1 includes a coil 2 as a magnetic field generating unit for generating an external magnetic field by an input signal, and a magnetoresistive effect element for detecting the external magnetic field and converting it into an electric signal. R1 to R4. Although the coil 2 and each magnetoresistive effect element R1-R4 are electrically insulated via the insulating layer which is not shown in figure, they are arrange | positioned at intervals which can be magnetically coupled. That is, the coil 2 and the magnetoresistive elements R1 to R4 are disposed at positions where they are electrically insulated and can be magnetically coupled, and are disposed so as to overlap in plan view.

  Here, in FIG. 1, the magnetic coupling type isolator 1 including the signal processing circuit (IC) such as the differential amplifier 15 and the external output terminal 16 is defined, but the signal processing circuit is included in the magnetic coupling type isolator 1. A configuration including the coil 2, the magnetoresistive elements R1 to R4, and the terminals 10 to 14 shown in FIG. 3 without including (IC) can also be defined as the magnetically coupled isolator 1. In such a case, it is necessary to electrically connect the magnetically coupled isolator 1 to a signal processing circuit (IC) on the electronic device side.

  As shown in FIG. 3, the coil 2 includes a first magnetic field generation unit 3 and a second magnetic field generation unit 4 that extend in a strip shape in the X1-X2 direction. The first magnetic field generating unit 3 and the second magnetic field generating unit 4 are opposed to each other with an interval in the Y1-Y2 direction shown in the drawing. The first magnetic field generating unit 3 and the second magnetic field generating unit 4 are connected via connecting parts 17 and 18. Although the connection parts 17 and 18 are curving, it does not limit a form. A space 19 is formed by being surrounded by the first magnetic field generator 3, the second magnetic field generator 4, and the connecting portions 17 and 18.

  As shown in FIG. 4, the coil 2 has a shape in which a coil piece 2 'formed with a width dimension T4 is wound a plurality of times with a predetermined interval T5. Therefore, as shown in FIG. 4, the first magnetic field generating unit 3 and the second magnetic field generating unit 4 have a configuration in which a plurality of coil pieces 2 'are arranged in parallel in the Y1-Y2 direction.

  Two electrode pads 5 and 6 connected to the coil 2 are provided. The electrode pads 5 and 6 are circular, but the shape is not particularly limited. Further, the coil 2 is connected to the transmission circuit 7 through the electrode pads 5 and 6 as shown in FIG. When a current based on an input signal flows from the transmission circuit 7, an external magnetic field is generated from the coil 2. As shown in FIG. 4, the direction of current flow is antiparallel in the coil piece 2 ′ constituting the first magnetic field generation unit 3 and the coil piece 2 ′ constituting the second magnetic field generation unit 4. Therefore, the external magnetic field H1 generated by the coil piece 2 'constituting the first magnetic field generation unit 3 and the external magnetic field H2 generated by the coil piece 2' constituting the second magnetic field generation unit 4 are opposite to each other. As shown in FIGS. 3 and 4, magnetoresistive elements R1 to R4 are insulated below (may be above) the first magnetic field generator 3 and below (may be above) the second magnetic field generator. Oppositely arranged via a layer (not shown). Then, the external magnetic field H3 acting from the first magnetic field generating unit 3 on the first magnetoresistive element R1 and the fourth magnetoresistive element R4 arranged to face the first magnetic field generating unit 3, and the generation of the second magnetic field. The external magnetic field H4 acting from the second magnetic field generating unit 4 on the second magnetoresistive effect element R2 and the third magnetoresistive effect element R3 arranged to face the part 4 is antiparallel.

  As shown in FIG. 2, the first magnetoresistive element R1 and the second magnetoresistive element R2 are connected in series, and the third magnetoresistive element R3 and the fourth magnetoresistive element R4 are connected in series. . The first magnetoresistive element R1 and the third magnetoresistive element R3 are connected to an input terminal (input pad) 10. In this embodiment, there is one input terminal 10. The second magnetoresistive element R2 and the fourth magnetoresistive element R4 are connected to separate ground terminals (ground pads) 11 and 12, respectively. Therefore, in this embodiment, there are two ground terminals 11 and 12.

  As shown in FIG. 2, a first output terminal (first output pad, OUT1) 13 is connected between the first magnetoresistive element R1 and the second magnetoresistive element R2, and the third magnetoresistive element A second output terminal (second output pad, OUT2) 14 is connected between the effect element R3 and the fourth magnetoresistive effect element R4. As shown in FIGS. 1 and 2, the output sides of the first output terminal 13 and the second output terminal 14 are connected to a differential amplifier 15. As shown in FIG. 1, the output side of the differential amplifier 15 is connected to the external output terminal 16.

  As shown in FIG. 3, the first magnetoresistive effect element R <b> 1 arranged to face the first magnetic field generating unit 3 of the coil 2 is arranged on the X1 side, and the fourth magnetoresistive effect element R4 is arranged on the X2 side. In addition, the second magnetoresistive element R2 disposed opposite to the second magnetic field generator 4 of the coil 2 is disposed on the X1 side, and the third magnetoresistive element R3 is disposed on the X2 side.

  As shown in FIG. 3, the first wiring pattern 20 connects the first magnetoresistive element R <b> 1 and the third magnetoresistive element R <b> 3. The first wiring pattern 20 is located in an enclosed area S that linearly surrounds the elements R1 to R4 in plan view. The first wiring pattern 20 is formed obliquely when viewed from the X1-X2 direction and the Y1-Y2 direction. A second wiring pattern 21 branches from the first wiring pattern 20. The second wiring pattern 21 extends from the internal position of the enclosed area S to the outside of the enclosed area S and is connected to the input terminal 10.

  Further, as shown in FIG. 3, the first magnetoresistive element R <b> 1 and the second magnetoresistive element R <b> 2 are connected by the third wiring pattern 22. The third wiring pattern 22 is formed extending in the Y1-Y2 direction. Further, the fourth wiring pattern 23 branches from the third wiring pattern 22 toward the outside of the enclosed region S. The fourth wiring pattern 23 is connected to the first output terminal 13.

  Further, as shown in FIG. 3, the fifth wiring pattern 24 connects the third magnetoresistive effect element R3 and the fourth magnetoresistive effect element R4. The fifth wiring pattern 24 is formed extending in the Y1-Y2 direction. Further, a sixth wiring pattern 25 branches from the fifth wiring pattern 24 toward the outside of the enclosed region S. The sixth wiring pattern 25 is connected to the second output terminal 14.

  Further, as shown in FIG. 3, the seventh magnetoresistive effect element R <b> 2 and the first ground terminal 11 are connected by a seventh wiring pattern 26. The fourth magnetoresistive element R4 and the second ground terminal 12 are connected by the eighth wiring pattern 27.

  As illustrated in FIG. 3, the terminals 10 to 14 are arranged in a line at a predetermined interval in the X1-X2 direction. Therefore, wiring (electrical connection) with the signal processing circuit (IC) side can be easily performed. And the input terminal 10 provided only one is arrange | positioned in the center position of these terminals 10-14. By arranging in this way, the wiring patterns can be routed so as not to overlap each other in plan view.

  However, the form of the wiring pattern is not limited to FIG. There may be a portion overlapping the wiring patterns in a plan view. Further, instead of the configuration of FIG. 3, a configuration in which a ground terminal is provided at the position of the input terminal 10 and an input terminal is provided at the locations of the ground terminals 11 and 12 may be employed. In such a case, there are one ground terminal and two input terminals.

  As shown in FIG. 3, an upper shield film (first shield film) 41 and a lower shield film (second shield film) 42 so as to overlap with the coil 2 and the magnetoresistive elements R1 to R4 which are magnetic field generating parts in plan view. Is provided. A middle shield (third shield film) 43 is provided so as to surround the magnetoresistive elements R1 to R4.

  FIG. 5 is a partial cross-sectional view of the magnetically coupled isolator according to the embodiment of the present invention. In the magnetically coupled isolator shown in FIG. 5, a silicon oxide film 52 that is an insulating layer is formed on a silicon substrate 51 that is a substrate. As the silicon oxide film 52, a silicon oxide film formed by thermal oxidation or a silicon oxide film formed by CVD is used.

  A lower shield film 42 is formed at a predetermined position on the silicon oxide film 52, that is, below the formation region of the coil 2 in the thickness direction (position overlapping the coil 2 and the magnetoresistive elements R1 to R4 in plan view). ing. As a material constituting the lower shield film 42, a high magnetic permeability material such as an amorphous magnetic material, a permalloy magnetic material, or an iron microcrystalline material can be used. The lower shield film 42 can be formed by photolithography and etching after the material is formed.

  A polyimide layer 53 is formed as an insulating layer on the silicon oxide film 52 on which the lower shield film 42 is formed. The polyimide layer 53 can be formed by applying and curing a polyimide material.

  A silicon oxide film 54 and an aluminum oxide film 55 are sequentially formed on the polyimide layer 53. The silicon oxide film 54 and the aluminum oxide film 55 can be formed by a method such as sputtering.

  On the aluminum oxide film 55, magnetoresistive elements R1 to R4 are formed. The magnetoresistive elements R1 to R4 are all formed in the same layer configuration. Each of the magnetic detection elements R1 to R4 is formed with a structure shown in FIG. 6, for example.

  Reference numeral 30 shown in FIG. 6 is a lower electrode layer. A multilayer film 31 is formed on the lower electrode layer 30. The multilayer film 31 is formed by laminating an antiferromagnetic layer 32, a pinned magnetic layer 33, an insulating barrier layer 34, a free magnetic layer 35, and a protective layer 36 in this order from the bottom. The free magnetic layer 35, the insulating barrier layer 34, the pinned magnetic layer 33, and the antiferromagnetic layer 32 may be stacked in this order from the bottom.

  The antiferromagnetic layer 32 is, for example, an antiferromagnetic material containing element α (where α is one or more elements among Pt, Pd, Ir, Rh, Ru, and Os) and Mn. Formed with. A seed layer for adjusting crystal orientation may be provided between the antiferromagnetic layer 32 and the lower electrode layer 30.

  The pinned magnetic layer 33 is pinned in the Y direction by an exchange coupling magnetic field (Hex) generated at the interface with the antiferromagnetic layer 32. Here, the term “magnetization fixed” refers to a state in which magnetization does not fluctuate at least with respect to an external magnetic field that acts on the magnetoresistive elements R1 to R4 from the coil 2. In FIG. 6, the pinned magnetic layer 33 has a single layer structure such as CoFe. However, the pinned magnetic layer 33 has a laminated structure, particularly a laminated ferrimagnetic structure formed of a magnetic layer / nonmagnetic intermediate layer / magnetic layer. This is preferable because the magnetization fixing force can be increased.

  An insulating barrier layer 34 is formed on the fixed magnetic layer 33. The insulating barrier layer 34 is made of, for example, titanium oxide (Ti—O) or magnesium oxide (Mg—O). A free magnetic layer 35 is formed on the insulating barrier layer 34. In FIG. 6, the free magnetic layer 35 has a single layer structure, but can also be formed by a laminated structure of magnetic layers. The free magnetic layer 35 is preferably formed of a single layer structure of NiFe or a laminated structure containing NiFe. A protective layer 36 made of a nonmagnetic metal material such as Ta is formed on the free magnetic layer 35.

  Both side end surfaces 31a, 31a of the multilayer film 31 in the X1-X2 direction (X direction) are formed as inclined surfaces so that the width dimension in the X direction gradually decreases from the lower side toward the upper side. However, it may be a vertical surface instead of an inclined surface.

As shown in FIG. 6, an insulating layer 37 is formed from the lower electrode layer 30 to the side end faces 31a and 31a. The insulating layer 37 is formed of an existing insulating material such as Al ₂ O ₃ or SiO ₂ . Further, the upper electrode layer 40 is formed from the insulating layer 37 to the multilayer film 31.

  Next, the output of the bridge circuit with respect to the external magnetic field will be described. For example, assuming that the magnetization of the fixed magnetic layer 33 of each magnetoresistive effect element R1-R4 is fixed in the Y1 direction, each of the external magnetic fields H3, H4 shown in FIG. 4 enters each magnetoresistive effect element R1 to R4. The magnetizations of the free magnetic layers 35 of the first magnetoresistive element R1 and the fourth magnetoresistive element R4 are inclined toward the Y1 direction. Therefore, the electrical resistance values of the first magnetoresistive element R1 and the fourth magnetoresistive element R4 are reduced. On the other hand, the magnetizations of the second magnetoresistive element R2 and the third magnetoresistive element R3 are inclined toward the Y2 direction. Therefore, the electrical resistance values of the second magnetoresistive effect element R2 and the third magnetoresistive effect element R3 are increased. As a result, the midpoint potential between the first magnetoresistive effect element R1 and the second magnetoresistive effect element R2 and the midpoint potential between the third magnetoresistive effect element R3 and the fourth magnetoresistive effect element R4 fluctuate. Dynamic output can be obtained. As described above, in the magnetically coupled isolator 1, electrical signals can be transmitted from the coil 2 via the magnetoresistive elements R1 to R4.

  In the present embodiment, all magnetoresistive elements R1 to R4 are formed with the same layer configuration. Here, the “layer configuration” includes not only the stacking order and material, but also the magnetization direction of the pinned magnetic layer 33. Then, as shown in FIG. 3, the first magnetoresistive element R <b> 1 and the fourth magnetoresistive element R <b> 4 are arranged at a position facing the first magnetic field generating unit 3 of the coil 2, and opposed to the second magnetic field generating unit 4. The second magnetoresistive effect element R2 and the third magnetoresistive effect element R3 are arranged at the positions to be operated. Then, wiring is performed as shown in FIG. 3, and a magnetoresistive effect element R1 to R4 constitutes a bridge circuit. In the present embodiment, since all the magnetoresistive elements R1 to R4 are formed in the same layer configuration, it is easy to match the resistance values and temperature characteristics of all the magnetoresistive elements R1 to R4, and each magnetoresistive element The effect elements R1 to R4 can be formed easily and appropriately. And as shown in FIG. 3, a bridge circuit can be comprised simply and appropriately by arrange | positioning the magnetoresistive effect elements R1-R4 and the coil 2. FIG.

  Magnetoresistive elements R1 to R4 in this embodiment are TMR elements (tunnel type magnetoresistive elements). Therefore, the electrode layers 30 and 40 are provided above and below the multilayer film 31. Then, a current flows in a direction perpendicular to the film surface of each layer of the multilayer film 31. Such a magnetoresistive effect element is called a CPP (current perpendicular to the plane) type. In addition to the TMR element, the CPP type includes a CPP-GMR element. In the CPP-GMR element, a nonmagnetic conductive layer such as Cu is used instead of the insulating barrier layer 34 shown in FIG.

  As shown in FIG. 4, the wiring pattern 24 is formed integrally with the lower electrode layer 30. The wiring pattern 24 may be formed separately from the lower electrode layer 30, but even in such a case, the wiring pattern 24 and the lower electrode layer 30 are electrically connected. Further, the wiring pattern 27 is formed integrally with the upper electrode layer 40. Although the wiring pattern 27 may be formed separately from the upper electrode layer 40, the wiring pattern 27 and the upper electrode layer 40 are electrically connected even in such a case. As described above, in the TMR element, the electrode layers 30 and 40 are formed above and below the multilayer film 31, so that the wiring pattern connected to the electrode layers 30 and 40 is formed in a plurality of layers.

  In the mode shown in FIG. 3, the wiring patterns 20, 21, 26, 27 are formed in the upper stage, and the wiring patterns 22, 23, 24, 25 are formed in the lower stage. The reverse may be possible.

  Returning to FIG. 5, an electrode 56 is formed on the aluminum oxide film 55 so as to be electrically connected to the upper electrode layer 40 of the magnetoresistive effect elements R1 to R4. Further, an electrode 56 is formed on the outer side of the middle shield film so as to be electrically connected to a pad to be described later. The electrode 56 can be formed by photolithography and etching after forming an electrode material.

  On the aluminum oxide film 55, a middle shield film 43 is formed so as to surround the magnetoresistive elements R1 to R4. As a material constituting the middle shield film 43, a high magnetic permeability material such as an amorphous magnetic material, a permalloy-based magnetic material, or an iron-based microcrystalline material can be used. The thickness of the middle shield film 43 is preferably 0.5 μm to 10 μm in consideration of film stress. The middle shield film 43 can be formed by photolithography and etching after the material is formed. Alternatively, the middle shield film 43 can be formed by photolithography and plating after forming a base material.

  A polyimide layer 57 is formed as an insulating layer on the aluminum oxide film 55 on which the magnetoresistive elements R1 to R4, the electrode 56, and the middle shield film 43 are formed. The polyimide layer 57 can be formed by applying and curing a polyimide material.

  A silicon oxide film 58 is formed on the polyimide layer 57. The silicon oxide film 58 can be formed by a method such as sputtering.

  A coil 2 is formed on the silicon oxide film 58. The coil 2 can be formed by photolithography and etching after the coil material is deposited. Alternatively, the coil 2 can be formed by photolithography and plating after forming the base material. A coil electrode 59 is formed on the silicon oxide film 58. The coil electrode 59 can be formed by photolithography and etching after forming an electrode material. Alternatively, the coil electrode 59 can be formed by photolithography and plating after the base material is deposited.

  On the silicon oxide film 58 on which the coil 2 and the coil electrode 59 are formed, a polyimide layer 60 is formed as an insulating layer. The polyimide layer 60 can be formed by applying and curing a polyimide material.

  An upper shield film 41 is formed at a predetermined position on the polyimide layer 60, that is, above the coil 2 in the thickness direction (position overlapping the coil 2 and the magnetoresistive elements R1 to R4 in plan view). As a material constituting the upper shield film 41, a high magnetic permeability material such as an amorphous magnetic material, a permalloy-based magnetic material, or an iron-based microcrystalline material can be used. The upper shield film 41 can be formed by photolithography and etching after the material is formed. Alternatively, the upper shield film 41 can be formed by photolithography and plating after forming a base material.

  On the polyimide layer 60 on which the upper shield film 41 is formed, a silicon oxide film 62 is formed as an overcoat layer. A contact hole is formed in the regions of the silicon oxide film 62, the polyimide layers 57 and 60, the coil electrode 59 of the silicon oxide film 58, and the pad electrode 56, and a pad 61 is formed in the contact hole. Thereby, the pad 61 and the coil electrode 59 are electrically connected, and the pad 61 and the electrode 56 are electrically connected.

  In the configuration shown in FIG. 5, the silicon oxide films 54 and 58 may not be provided.

  As can be seen from FIG. 5, the magnetically coupled isolator according to the present embodiment includes an upper shield film 41 and a lower shield film 42 disposed so as to overlap the coil 2 and the magnetoresistive effect elements R1 to R4, and a magnetoresistive effect. And a middle shield 43 disposed so as to surround the elements R1 to R4. As described above, since the upper shield film 41, the lower shield film 42, and the middle shield film 43 having a predetermined thickness are disposed around the magnetoresistive elements R1 to R4, sufficient resistance to an external magnetic field and EMS is provided. Can be secured.

  The upper shield film preferably has a function of enhancing the magnetic field applied from the coil 2 to the bridge circuit composed of the magnetoresistive elements R1 to R4. Further, the upper shield film 41, the lower shield film 42, and / or the middle shield film 43 have a point-symmetric shape in plan view, and it is preferable that the respective centers of symmetry coincide with each other. By adopting such a shape, the magnitude of the magnetic field applied to the magnetoresistive elements R1 to R4 can be made more uniform, and the midpoint potential shift can be mitigated.

  Here, the desirable thicknesses of the upper shield film 41, the lower shield film 42, and the middle shield film 43 will be described. In the configuration in which the upper shield film 41 and the lower shield film 42 are provided around the magnetoresistive elements R1 to R4 and the middle shield film 43 is not provided, the thicknesses of the upper shield film 41 and the lower shield film 42 are similarly changed. The ratio of the magnetic field applied to the magnetoresistive effect element when an external magnetic field of 20 mT was applied to the coupled isolator from the direction of arrow A in FIG. 5 (upward with respect to the upper shield film 41) was examined. The result is shown in FIG. As for the ratio of the magnetic field applied to the magnetoresistive element when an external magnetic field is applied, the closer to zero, the higher the shielding effect. The upper shield film and the lower shield film were squares of 200 μm × 200 μm, and the middle shield film was ring-shaped with an outer radius of 340 μm and an inner radius of 290 μm. Further, the distance between the lower shield film 42 and the magnetoresistive effect element was 20 μm, and the distance between the magnetoresistive effect element and the upper shield film 41 was 17 μm.

  As can be seen from FIG. 7, when the thickness of the shield film is increased from 0 μm (none) to the upper shield film 41 and the lower shield film, the shield effect is rapidly increased, and a high shield effect is maintained up to a thickness of 15 μm. If the thickness of the upper shield film 41 and the lower shield film 42 is 0.5 μm or more, it can be reduced to 30% or less of the external magnetic field, which is preferable. That is, when the thickness of the upper shield film 41 and the lower shield film 42 is 0.5 μm to 15 μm, the shielding effect against the external magnetic field is enhanced.

  Next, in the configuration in which the upper shield film 41 and the lower shield film 42 are provided around the magnetoresistive effect elements R1 to R4 and the middle shield film 43 is not provided, the thickness of the lower shield film 42 is fixed to 1 μm, and the upper shield film The magnetic field applied to the magnetoresistive effect element when an external magnetic field of 20 mT is applied to the magnetically coupled isolators with different thicknesses 41 from the direction of arrow A in FIG. 5 (upward with respect to the upper shield film 41). The proportion of each was examined. The result is shown in FIG. The upper shield film and the lower shield film were squares of 200 μm × 200 μm, and the middle shield film was ring-shaped with an outer radius of 340 μm and an inner radius of 290 μm. Further, the distance between the lower shield film 42 and the magnetoresistive effect element was 20 μm, and the distance between the magnetoresistive effect element and the upper shield film 41 was 17 μm.

  As can be seen from FIG. 8, even in this case, when the thickness of the shielding film is increased from 0 μm (none) to the shielding film, the shielding effect is rapidly increased, and the high shielding effect is maintained up to a thickness of 15 μm. . A thickness of the upper shield film 41 of 0.5 μm or more is preferable because it can be reduced to 20% or less of the external magnetic field. That is, when the thickness of the upper shield film 41 is 0.5 μm to 15 μm, the shielding effect against the external magnetic field is enhanced.

  Next, in the configuration in which the upper shield film 41 and the lower shield film 42 are provided around the magnetoresistive effect elements R1 to R4 and the middle shield film 43 is not provided, the thickness of the upper shield film 41 is fixed to 1 μm, and the lower shield film The magnetic field applied to the magnetoresistive element when an external magnetic field of 20 mT is applied to the magnetically coupled isolators with different thicknesses 42 from the direction of arrow B in FIG. 5 (downward with respect to the lower shield film 42). The proportion of each was examined. The result is shown in FIG. The upper shield film and the lower shield film were squares of 200 μm × 200 μm, and the middle shield film was ring-shaped with an outer radius of 340 μm and an inner radius of 290 μm. Further, the distance between the lower shield film 42 and the magnetoresistive effect element was 20 μm, and the distance between the magnetoresistive effect element and the upper shield film 41 was 17 μm.

  As can be seen from FIG. 9, even in this case, when the thickness of the shielding film is increased from 0 μm (none) to the lower shielding film 42, the shielding effect is rapidly increased, and a high shielding effect is maintained up to a thickness of 15 μm. . A thickness of the lower shield film 42 of 0.5 μm or more is preferable because it can be reduced to 20% or less of the external magnetic field. That is, when the thickness of the lower shield film 42 is 0.5 μm to 15 μm, the shielding effect against the external magnetic field is enhanced.

  Next, in the configuration in which the upper shield film 41 and the lower shield film 42 are provided around the magnetoresistive elements R1 to R4 and the middle shield film 43 is not provided, the thicknesses of the upper shield film 41 and the lower shield film 42 are similarly changed. When a current of 10 mA is passed through the coil 2 (line width: 2 μm, thickness: 2.2 μm, 8 turns) of the magnetically coupled isolator, the magnetic field in the film surface direction applied from the coil 2 to the magnetoresistive effect element The size of each was examined. The result is shown in FIG. In addition, the vertical axis | shaft of FIG. 10 shows the value normalized by the saturation value. The larger the magnitude of this magnetic field, the better.

  As can be seen from FIG. 10, the magnitude of the magnetic field is saturated when the thickness of the shield film is approximately 10 μm or more. Further, it is preferable that the thickness of the shield film is 0.5 μm or more because a value of 90% or more of the saturation value can be obtained. That is, when the thickness of the shield film is 0.5 μm to 10 μm, the shield effect can be exhibited while the enhancement effect of the magnetic field of the coil 2 is exhibited.

  If the shield film thickness is increased more than necessary, when an unnecessary external magnetic field is applied to the shield film from the vertical direction (for example, when an external magnetic field is applied from above the upper shield film), the magnetoresistive element It is conceivable to increase the unnecessary magnetic field. This is because, as the shield film thickness increases, the demagnetizing field in the film thickness direction decreases, and the perpendicular component of the magnetization with respect to the film surface tends to increase (the permeability in the film thickness direction increases). As a result, the upper shield This is because unnecessary magnetic flux emitted from the film and the lower shield film is easily applied to the magnetoresistive element. For this reason, it is preferable that the magnetic permeability in the in-plane direction of the shield film is large and the magnetic permeability in the vertical direction is small. Therefore, it is preferable to set the shield film thickness to an appropriate thickness without making it thicker than necessary.

  The present invention is not limited to the above embodiment, and can be implemented with appropriate modifications. For example, the material, the arrangement position of each layer, the thickness, the size, the manufacturing method, and the like in the above embodiment can be changed as appropriate. In addition, the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.

  The present invention can be applied to a magnetic coupler, a current sensor, and the like.

DESCRIPTION OF SYMBOLS 1 Magnetic coupling type isolator 2 Coil 2 'Coil piece 3 1st magnetic field generation part 4 2nd magnetic field generation part 7 Transmission circuit 10 Input terminal 11,12 Ground terminal 13,14 Output terminal 15 Differential amplifier 16 External output terminal 20-27 Wiring pattern 30 Lower electrode layer 31 Multilayer film 32 Antiferromagnetic layer 33 Fixed magnetic layer 34 Insulating barrier layer 35 Free magnetic layer 37 Insulating layer 40 Upper electrode layer 41 Upper shield film 42 Lower shield film 43 Middle shield film H1 to H4 External magnetic field R1 to R4 magnetoresistive effect element

Claims (6)

  A magnetic field generator for generating an external magnetic field by an input signal, and a position that is electrically insulated from the magnetic field generator and capable of magnetic coupling, and is disposed so as to overlap the magnetic field generator in plan view A magnetoresistive element for detecting the external magnetic field and converting it into an electric signal, a first shield film disposed so as to overlap the magnetic field generator and the magnetoresistive element in plan view, and 2 shield films and a third shield film disposed so as to surround the magnetoresistive effect element, wherein the first shield film and / or the second shield film has a thickness of 0.5 μm to 15 μm. And a magnetically coupled isolator.   2. The magnetically coupled isolator according to claim 1, wherein the first shield film and / or the second shield film has a thickness of 0.5 μm to 10 μm.   The magnetic field generation unit includes a first magnetic field generation unit and a second magnetic field generation unit that generate external magnetic fields in directions opposite to each other, and the magnetoresistive effect element is disposed to face the first magnetic field generation unit. And the magnetoresistive effect element disposed opposite to the second magnetic field generating unit, and each magnetoresistive effect element has the same layer configuration, and the magnetoresistive element disposed opposite to the first magnetic field generating unit. 3. The magnetically coupled isolator according to claim 1, wherein the effect element and the magnetoresistive effect element arranged to face the second magnetic field generating unit constitute a bridge circuit.   4. The magnetically coupled isolator according to claim 3, wherein the first shield film has a function of enhancing a magnetic field applied to the bridge circuit from the magnetic field generator.   5. The magnetic coupling type according to claim 1, wherein the first shield film, the second shield film, and / or the third shield film are made of a high magnetic permeability material. Isolator.   The first shield film, the second shield film, and / or the third shield film have a point-symmetric shape in plan view, and the respective centers of symmetry coincide with each other. The magnetically coupled isolator according to any one of claims 1 to 5.

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