CN210665858U - Large-dynamic-range magnetic sensor assembly - Google Patents
Large-dynamic-range magnetic sensor assembly Download PDFInfo
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- CN210665858U CN210665858U CN201921470468.1U CN201921470468U CN210665858U CN 210665858 U CN210665858 U CN 210665858U CN 201921470468 U CN201921470468 U CN 201921470468U CN 210665858 U CN210665858 U CN 210665858U
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Abstract
The embodiment of the utility model discloses big dynamic range magnetic sensor subassembly, include: the first magnet structure is positioned on one side of the circuit board, a first connecting line formed by a central point of a first magnetic pole of the first magnet structure and a central point of the magnetic sensitive element is vertical to the plane where the first magnetic pole is positioned, a central point of a second magnetic pole of the first magnet structure is positioned on an extension line of the first connecting line, and the sensitive direction of the magnetic sensitive element is positioned in the plane of the magnetic sensitive element and is vertical to the first connecting line; the magnetic sensing element comprises at least one magnetic sensing unit, the magnetic sensing unit comprises a bottom electrode, a top electrode and a multilayer thin film structure positioned between the bottom electrode and the top electrode, the multilayer thin film structure comprises a free layer, the magnetic moment direction of the free layer is perpendicular to the plane of the magnetic sensing element when no external magnetic field exists, and the magnetic moment direction of the free layer deviates when the external magnetic field is applied. The embodiment of the utility model provides a can measure big magnetic field.
Description
Technical Field
The embodiment of the utility model provides a relate to the magnetic sensing technique, especially relate to a big dynamic range magnetic sensor subassembly.
Background
As solid state magneto-sensitive devices develop and mature, magnetic sensors integrated with magneto-sensitive devices are increasingly being fabricated as current sensors for the measurement of electrical current. Compared with the current transformer, Rogowski coil and other inductive principle devices in the traditional current sensor, the magnetic sensor has the characteristics of small volume, low cost, capability of measuring direct current and the like.
In the current solid-state magnetic sensing devices, the process of the Hall device is the most mature, and the application is the most extensive, but the current carrier movement in the Hall device is greatly influenced by the temperature, so that the temperature stability of the Hall device is poor, and the application of the Hall device at high temperature is limited. Ferromagnetic magnetoresistive device technology has been developed in recent years to be superior to hall devices in temperature stability, but saturates under larger magnetic fields, resulting in measurement failures.
SUMMERY OF THE UTILITY MODEL
An embodiment of the utility model provides a big dynamic range magnetic sensor subassembly to solve the problem that current sensor easily became invalid under great magnetic field.
An embodiment of the utility model provides a big dynamic range magnetic sensor subassembly, include: the circuit board comprises a first magnet structure, a circuit board and a magnetic sensing element arranged on the circuit board, wherein the first magnet structure is positioned on one side of the circuit board, a first connecting line formed by a central point of a first magnetic pole of the first magnet structure and a central point of the magnetic sensing element is vertical to the plane of the first magnetic pole, a central point of a second magnetic pole of the first magnet structure is positioned on an extension line of the first connecting line, and the sensitive direction of the magnetic sensing element is positioned in the plane of the magnetic sensing element and is vertical to the first connecting line;
the magnetic sensing element comprises at least one magnetic sensing unit, the magnetic sensing unit comprises a bottom electrode, a top electrode and a multilayer thin film structure positioned between the bottom electrode and the top electrode, the multilayer thin film structure comprises a seed layer, an anti-ferromagnetic layer, an exchange bias layer, an isolation layer and a free layer which are sequentially stacked, the exchange bias layer comprises a ferromagnetic layer, a spacer layer and a pinning layer, and the magnetic moment direction of the pinning layer is in the plane of the magnetic sensing element; when no external magnetic field exists, the direction of the magnetic moment of the free layer is vertical to the plane of the magnetic sensitive element, and when the external magnetic field is applied, the direction of the magnetic moment of the free layer deviates.
Further, still include: the circuit board comprises a first magnet structure, a second magnet structure, a first connecting wire and a second magnet structure, wherein the first magnet structure is arranged on one side of the circuit board and deviates from the first magnet structure, the central point of the first magnetic pole of the second magnet structure and the central point of the second magnetic pole are both arranged on the extension line of the first connecting wire, the second magnetic pole of the second magnet structure faces the circuit board, the second magnet structure is arranged opposite to the first magnet structure, and the second magnetic pole of the second magnet structure is opposite to the first magnetic pole of the first magnet structure in polarity.
Further, the first magnet structure includes a first magnet and a first magnet seat, the first magnet being embedded in the first magnet seat; the second magnet structure comprises a second magnet and a second magnet seat, and the second magnet is embedded in the second magnet seat;
the first magnet and the second magnet have the same shape, and the same shape is a cylinder shape, a cuboid shape, a frustum shape or a circular truncated cone shape;
the first magnet and the second magnet are made of the same material, and the same material is samarium cobalt, neodymium iron boron, alnico or ferrite.
Furthermore, the plane of the bottom electrode of the magnetosensitive unit is parallel to the plane of the film layer of the multilayer thin film structure, and the plane of the top electrode of the magnetosensitive unit is parallel to the plane of the film layer of the multilayer thin film structure; alternatively, the first and second electrodes may be,
the plane of the bottom electrode of the magnetic sensing unit is perpendicular to the plane of the film layer of the multilayer film structure, and the plane of the top electrode of the magnetic sensing unit is perpendicular to the plane of the film layer of the multilayer film structure.
Furthermore, the circuit structure of the magnetic sensing element is a half-bridge structure, two bridge arms of the half-bridge structure are formed by connecting a plurality of magnetic sensing units in series and in parallel, the magnetic moment directions of the pinning layers of each magnetic sensing unit in the bridge arms are consistent, and the magnetic moment directions of the pinning layers of the magnetic sensing units of the two bridge arms are opposite.
Furthermore, the circuit structure of the magnetic sensing element is a full-bridge structure, four bridge arms of the full-bridge structure are formed by connecting a plurality of magnetic sensing units in series and in parallel, the magnetic moment directions of the pinning layers of each magnetic sensing unit in the bridge arms are consistent, the magnetic moment directions of the pinning layers of the magnetic sensing units of two bridge arms which are in cross correspondence in the four bridge arms are consistent, and the magnetic moment directions of the pinning layers of the magnetic sensing units of two adjacent bridge arms in the four bridge arms are opposite.
Further, the magneto-sensitive element is a giant magneto-resistive element or a tunnel magneto-resistive element.
In the embodiment of the present invention, when there is no external magnetic field, the direction of the magnetic moment of the free layer is the same as the direction of the bias magnetic field generated by the first magnet structure at the magnetic sensor; when a measured magnetic field is applied, the direction of the magnetic moment of the free layer is deviated. The embodiment of the utility model provides an in, the direction of magnetizing of first magnet structure perpendicular to magnetic sensing element place plane, and the magnetic pole of first magnet structure is just to magnetic sensing element, consequently, the bias magnetic field that first magnet structure produced in magnetic sensing element department is the same with the magnetic moment direction of free layer when no external magnetic field, bias magnetic field can reduce the magnetic moment of free layer and change by the deflection under the magnetic field of surveying, and the magnetic field on the perpendicular magnetic sensing element surface that first magnet structure produced is very big, make magnetic sensing element be difficult to the saturation, consequently, can reach the effect that increases magnetic field dynamic range, make magnetic sensing element can detect bigger external magnetic field, solve current magnetic sensing element and measure the problem of inefficacy under big magnetic field.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic diagram of a high dynamic range magnetic sensor assembly provided by an embodiment of the present invention;
fig. 2 is a schematic diagram of a tunnel magnetoresistance sensitive unit in a large dynamic range magnetic sensor assembly provided by an embodiment of the present invention;
fig. 3 is a schematic diagram of a high dynamic range magnetic sensor assembly provided by an embodiment of the present invention;
fig. 4 is an assembly schematic diagram of a large dynamic range magnetic sensor assembly provided by an embodiment of the present invention;
fig. 5 is a schematic diagram of a high dynamic range magnetic sensor assembly provided by an embodiment of the present invention;
fig. 6 is a schematic diagram of a giant magnetoresistance sensitive unit in a large dynamic range magnetic sensor assembly according to an embodiment of the present invention;
fig. 7 is a circuit diagram of a full bridge configuration of a large dynamic range magnetic sensor assembly provided by an embodiment of the present invention;
fig. 8 is a circuit diagram of a full bridge configuration of a large dynamic range magnetic sensor assembly provided by an embodiment of the present invention;
fig. 9 is a schematic response curve diagram of a magnetic sensor assembly in a full-bridge configuration according to an embodiment of the present invention;
FIG. 10 is a graph showing a response curve of a conventional magneto-sensitive element.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely through embodiments with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Referring to fig. 1, a schematic diagram of a large dynamic range magnetic sensor assembly according to an embodiment of the present invention is shown, and fig. 2 is a schematic structural diagram of a magnetic sensing unit. The present embodiment provides a large dynamic range magnetic sensor assembly comprising: the magnetic sensor comprises a first magnet structure 2, a circuit board (not shown) and a magnetic sensing element 1 arranged on the circuit board, wherein the first magnet structure 2 is positioned on one side of the circuit board, a first connecting line 23 formed by a central point 21 of a first magnetic pole 2a of the first magnet structure 2 and a central point of the magnetic sensing element 1 is vertical to the plane of the first magnetic pole 2a, a central point of a second magnetic pole 2b of the first magnet structure 2 is positioned on an extension line of the first connecting line 23, and the sensitive direction of the magnetic sensing element 1 is positioned in the plane of the magnetic sensing element 1 and is vertical to the first connecting line 23; as shown in fig. 2, the magneto-sensitive element 1 includes at least one magneto-sensitive cell 31, the magneto-sensitive cell 31 including a bottom electrode 101 and a top electrode 109 and a multilayer thin-film structure 1a located between the bottom electrode 101 and the top electrode 109, the multilayer thin-film structure 1a including a seed layer 102, an antiferromagnetic layer 103, an exchange bias layer 1b, a separation layer 107 and a free layer 108 which are sequentially stacked, the exchange bias layer 1b including a ferromagnetic layer 104, a spacer layer 105 and a pinned layer 106 and a magnetic moment direction 111 of the pinned layer 106 being in a plane of the magneto-sensitive element 1; in the absence of an applied magnetic field, the magnetic moment direction 112 of the free layer 108 is perpendicular to the plane of the magnetic sensor 1, and in the presence of an applied magnetic field, the magnetic moment direction 112 of the free layer 108 is displaced.
In this embodiment, the magnetic sensor 1 is disposed on a circuit board, the circuit board includes a first side surface and a second side surface, the optional circuit board is a PCB circuit board, the magnetic sensor 1 is welded on the first side surface of the circuit board, and the magnetic sensor 1 achieves a magnetic induction effect through a circuit of the circuit board. The first magnet arrangement 2 is located on one side of the circuit board, where the first magnet arrangement 2 may be located on a first side of the circuit board or on a second side of the circuit board. The first magnet structure 2 is integrated with a magnet having a first magnetic pole 2a and a second magnetic pole 2b, wherein the first magnetic pole 2a is selected to be an N-pole and the second magnetic pole 2b is an S-pole, or the first magnetic pole 2a is selected to be an S-pole and the second magnetic pole 2b is an N-pole, wherein the first magnetic pole 2a of the first magnet structure 2 faces the magneto-sensitive element 1, and the second magnetic pole 2b of the corresponding first magnet structure 2 faces away from the magneto-sensitive element 1.
In this embodiment, the central point 21 of the first magnetic pole 2a of the first magnet structure 2 is the central point of the shape of the plane where the first magnetic pole 2a is located, for example, the magnet in the first magnet structure 1 is a cylinder, the shape of the plane where the first magnetic pole is located is a circle, and the central point is the center of the circle. The central point of the magnetic sensing element 1 refers to the central point of the shape of the plane where the magnetic sensing element 1 is located, for example, the magnetic sensing element 1 is a sheet-shaped cuboid, the shape of the plane where the magnetic sensing element 1 is located is a rectangle, and the central point is the intersection point of two diagonal lines of the rectangle.
The center point 21 of the first magnetic pole 2a of the first magnet structure 2 is used as an end point, the center point of the magnetic sensing element 1 is used as another end point, and the connection can form a first connection line 23, the first connection line 23 is perpendicular to the plane of the first magnetic pole 2a, the center point of the second magnetic pole 2b of the first magnet structure 2 is located on the extension line of the first connection line 23, the first magnetic pole 2a of the first magnet structure 2 is opposite to the magnetic sensing element 1, the second magnetic pole 2b of the first magnet structure 2 is far away from the magnetic sensing element 1, and the center point is located on the extension line of the first connection line 23, obviously, the plane of the first magnet structure 2 is perpendicular to the first connection line 23, and the magnetizing direction of the first magnet structure 2 is parallel to the first connection line 23. Here, the plane of the first magnet structure 2 is an X-Y plane, and the magnetizing direction of the first magnet structure 2 and the extending direction of the first connecting line 23 are both Z directions.
The sensitive direction of the magneto-sensitive element 1 is in the plane of the magneto-sensitive element 1 and perpendicular to the first connecting line 23, so that the plane of the magneto-sensitive element 1 is perpendicular to the first connecting line 23. Therefore, the plane of the magnetic sensing element 1 is parallel to the plane of the first magnet structure 2 and is both an X-Y plane, the sensitive direction of the magnetic sensing element 1 is in the X-Y plane, and the magnetizing direction of the first magnet structure 2 is perpendicular to the sensitive direction of the magnetic sensing element 1.
In this embodiment, according to the magnetic field distribution rule that magnet produced in the space, first magnet structure 2 produces the magnetic field along the Z direction, and magnetic sensing element 1 is parallel with the plane of first magnet structure 2 place, therefore first magnet structure 2 has the magnetic field along the Z direction in magnetic sensing element 1 department, and this magnetic field is in the utility model discloses in define for the bias magnetic field.
In the present embodiment, the magnetic sensing element 1 includes a substrate 3 and a magnetic sensing unit 31 formed on the substrate 3, and the substrate 3 may be a silicon substrate, but is not limited thereto. The optional bottom electrode 101 is located on the substrate 3, and in other embodiments other layers of the magnetosensitive cell may be located on the substrate. Between the bottom electrode 101 and the top electrode 109 is a multilayer thin film structure 1a, the multilayer thin film structure 1a includes a seed layer 102, an antiferromagnetic layer 103, an exchange bias layer 1b, a spacer layer 107, and a free layer 108, which are sequentially stacked, and the exchange bias layer 1b includes a ferromagnetic layer 104, a spacer layer 105, and a pinning layer 106.
The optional seed layer 102 is composed of a multi-layer film of Ta and Ru, for example, the seed layer 102 includes 4 layers of films, wherein the first and third layers are Ta metal layers, and the second and fourth layers are Ru metal layers, but the seed layer of the present invention is not limited to this number of layers and the stacking manner. The seed layer 102 is provided for lattice matching of the antiferromagnetic layer 103, and the seed layer 102 is provided so that the antiferromagnetic layer 103 is grown in accordance with a desired lattice, thereby reducing defects of the magneto-sensitive cell 31. Above the antiferromagnetic layer 103 is an exchange-bias layer 1b, which exchange-bias layer 1b includes ferromagnetic layer 104, spacer layer 105 and pinning layer 106. with the structure of exchange-bias layer 1b, the magnetic moment of pinning layer 106 will be fixed in the plane in which it lies, knowing that the magneto-sensitive element 1 lies in the X-Y plane, the direction of magnetic moment 111 of pinning layer 106 is in the X-Y plane. Referring to the magnetosensitive cell 31 shown in FIG. 2, the magnetic moment of the pinned layer 106 is in the X-Y plane and in the + X direction, i.e., the magnetic moment direction 111 of the pinned layer 106 is the + X direction in the X-Y plane.
Above the pinning layer 106 is a spacer layer 107, as shown in FIG. 2, the spacer layer 107 being composed of a metal oxide, with the metal oxides being magnesium oxide and aluminum oxide being optional. Above the isolation layer 107 is a free layer 108, and the free layer 108 is formed by compounding one or more materials of nickel Ni, iron Fe, cobalt Co and boron B. A top electrode 109 is arranged above the free layer 108, a magnetosensitive unit 31 which is a minimum unit of the magnetosensitive element 1 is formed from the top electrode 109 to the bottom electrode 101, and the magnetosensitive element 1 can be formed by connecting a plurality of minimum units in series and in parallel. The protective layer 110 is provided on the uppermost surface of the thin film layer of the entire magnetic sensor element 1, and the protective layer 110 can prevent the thin film from being damaged or oxidized.
In this embodiment, when there is no external magnetic field in the free layer 108, the magnetic moment direction 112 of the free layer 108 is perpendicular to the film plane, which is an X-Y plane, so that the magnetic moment direction 112 of the free layer 108 is a Z direction when there is no external magnetic field, and meanwhile, the magnetic moment direction 112 of the free layer 108 is the same as the direction of the bias magnetic field. The magnetic moment direction 112 of the free layer 108 is deviated when a measured magnetic field is applied. Given that the magnetization direction of the first magnet structure 2 is Z-direction, and the magnetic pole of the first magnet structure 2 is opposite to the magnetic sensing element 1, the bias magnetic field generated by the first magnet structure 2 at the magnetic sensing element 1 is the same as the magnetic moment direction 112 of the free layer 108 in the absence of an external magnetic field, which can reduce the deflection change of the magnetic moment of the free layer 108 under the measured magnetic field, so that the magnetic sensing element 1 is difficult to saturate, thereby achieving the effect of increasing the dynamic range of the magnetic field, and enabling the magnetic sensing element 1 to detect a larger external magnetic field.
In this embodiment, the process of detecting the magnetic field of the magnetic sensor 1 is that when there exists a magnetic field to be detected in the same or opposite direction to the magnetic moment 111 of the pinned layer 106, the magnetic moment 112 of the free layer 108 deviates, the magnetoresistance between the bottom electrode 101 and the top electrode 109 changes accordingly, and the magnitude of the magnetic field to be detected can be determined according to the resistance between the two electrodes. When the external field does not exist, the magnetic moment direction 112 of the free layer 108 is perpendicular to the magnetic moment direction 111 of the pinning layer 106, the magnetoresistance between the bottom electrode 101 and the top electrode 109 is kept unchanged, and the external field does not exist according to the resistance value between the two electrodes.
In this embodiment, when there is no external magnetic field, the direction of the magnetic moment of the free layer is the same as the direction of the bias magnetic field generated by the first magnet structure at the magnetic sensing element; when a measured magnetic field is applied, the direction of the magnetic moment of the free layer is deviated. In this embodiment, the magnetization direction of the first magnet structure is perpendicular to the plane of the magnetic sensor, and the magnetic pole of the first magnet structure faces the magnetic sensor, so that the bias magnetic field generated by the first magnet structure at the magnetic sensor is the same as the magnetic moment direction of the free layer in the absence of an external magnetic field, the bias magnetic field can reduce the deflection change of the magnetic moment of the free layer in the measured magnetic field, and the magnetic field generated by the first magnet structure perpendicular to the surface of the magnetic sensor is very large, so that the magnetic sensor is difficult to saturate, thereby achieving the effect of increasing the dynamic range of the magnetic field, enabling the magnetic sensor to detect a larger external magnetic field, and solving the problem of measurement failure of the existing magnetic sensor in a large magnetic field.
Exemplarily, on the basis of the above technical solution, as shown in fig. 3, the method further includes: second magnet structure 4, second magnet structure 4 is located the circuit board and deviates from one side of first magnet structure 2, and the central point 41 of the first magnetic pole 4a of second magnet structure 4 and the central point of second magnetic pole 4b all are located the extension line of first connecting line 23, and second magnetic pole 4b of second magnet structure 4 faces the circuit board, and second magnet structure 4 sets up and the polarity of the second magnetic pole 4b of second magnet structure 4 is opposite with the first magnetic pole 2a of first magnet structure 2 with first magnet structure 2 relatively.
In this embodiment, a second magnet structure 4 is added to the large dynamic range magnetic sensor assembly shown in fig. 1. The two magnetic poles of the second magnet structure 4 are located on the extension line of the first connecting line 23, so that the plane of the second magnet structure 4 is perpendicular to the first connecting line 23, the magnetizing direction of the second magnet structure 4 is parallel to the first connecting line 23, and thus it can be seen that the plane of the second magnet structure 4 is the X-Y plane, the magnetizing direction of the second magnet structure 4 is the Z direction, and the second magnet structure 4 generates a bias magnetic field along the Z-axis direction at the magneto-sensitive element 1. Adding the second magnet structure 4 on the basis of fig. 1, the magnetizing direction of the second magnet structure 4 is also perpendicular to the magnetic sensing element 1, so that the bias magnetic field component along the Z direction at the position of the magnetic sensing element 1 can be stronger.
And the second magnetic pole 4b of the second magnet structure 4 faces the magnetic sensing element 1 in the circuit board, the first magnetic pole 2a of the first magnet structure 2 faces the magnetic sensing element 1, the first magnet structure 2 and the second magnet structure 4 are located on two sides of the circuit board, the second magnetic pole 4b of the second magnet structure 4 is opposite to the first magnetic pole 2a of the first magnet structure 2 in polarity, so that the bias magnetic field component generated by the second magnet structure 4 at the magnetic sensing element 1 in the XY direction is opposite to the bias magnetic field component generated by the first magnet structure 2 at the magnetic sensing element 1 in the XY direction and has the same magnitude, and the bias magnetic field components of the two magnet structures at the magnetic sensing element 1 in the XY direction can be offset. In this way, by adding the second magnet structure 4 to the magnetic sensor 1, the second magnetic pole 4b of the second magnet structure 4 is arranged opposite to the first magnetic pole 2a of the first magnet structure 2, and the polarity of the magnetic poles is opposite, so that the bias magnetic field component along the XY plane at the position of the magnetic sensor element 1 of the first magnet structure 2 and the second magnet structure 4 can be reduced.
In this embodiment, on the basis of fig. 1, the second magnet structure 4 is added, and the second magnetic pole 4b of the second magnet structure 4 is arranged opposite to the first magnetic pole 2a of the first magnet structure 2 and has opposite magnetic pole polarities, so that the bias magnetic field component in the Z direction at the position of the magnetic sensor element 1 of the first magnet structure 2 and the second magnet structure 4 can be enhanced, and the bias magnetic field component in the XY plane at the position of the magnetic sensor element 1 of the first magnet structure 2 and the second magnet structure 4 can be reduced, so that the dynamic range of the measured magnetic field can be further increased, the influence of the bias magnetic field on the deflection of the free layer 108 can be reduced, and the measurement accuracy can be improved.
In this embodiment, the first magnetic pole 2a of the first magnet structure 2 may be an N pole, and the first magnetic pole 4a of the second magnet structure 4 may be an N pole; alternatively, the first magnetic pole 2a of the first magnet structure 2 may be an S-pole, and the first magnetic pole 4a of the second magnet structure 4 may be an S-pole. The perpendicular distance 42 from the center point 41 of the second magnetic pole 4b of the second magnet structure 4 to the magnetic sensor element 1 can also be selected to be equal to the perpendicular distance 22 from the center point 21 of the first magnetic pole 2a of the first magnet structure 2 to the magnetic sensor element 1, so that the bias magnetic field components along the XY plane of the first magnet structure 2 and the second magnet structure 4 at the position of the magnetic sensor element 1 can be approximated, and the bias magnetic field components along the XY plane of the first magnet structure 2 and the second magnet structure 4 at the position of the magnetic sensor element 1 can be reduced.
Alternatively, as shown in fig. 4, the first magnet structure 2 includes a first magnet 201 and a first magnet holder 202, and the first magnet 201 is embedded in the first magnet holder 202; the second magnet structure 4 includes a second magnet 401 and a second magnet holder 402, the second magnet 401 being embedded in the second magnet holder 402; the first magnet 201 and the second magnet 401 have the same shape, and the same shape is a cylinder shape, a rectangular parallelepiped shape, a truncated pyramid shape, or a circular truncated cone shape; the first magnet 201 and the second magnet 401 are made of the same material, which is samarium cobalt, neodymium iron boron, alnico, or ferrite. In this embodiment, the first magnet 201 and the second magnet 401 are both permanent magnets and can be formed by using the same material and shape, so that the bias magnetic field components along the XY plane at the position of the magnetic sensing element 1 of the first magnet structure 2 and the second magnet structure 4 can be further approximated, and the bias magnetic field components along the XY plane at the position of the magnetic sensing element 1 of the first magnet structure 2 and the second magnet structure 4 can be further reduced.
FIG. 4 also features the assembled structure of the magnetic sensor assembly. Wherein, the structure of magnetic sensor subassembly is: the magnetic sensor element 1 is located on the circuit board 5, and the circuit board 5 has a plurality of through holes for limiting the magnetic bases 202 and 402. The first magnet 201 is magnetized in the thickness direction (Z direction) and is located in a recess (not shown) of the first magnet holder 202. Similarly, the second magnet 401 is magnetized in the thickness direction (Z direction), the magnetization direction is the same as that of the first magnet 201, and the second magnet 401 is also located in the recess 403 of the second magnet holder 402. The magnet holders 202 and 402 are located opposite to the through-hole of the circuit board 5, and the circuit board 5 has a slot structure, so that the magnet holders 202 and 402 are aligned vertically and are clamped in the circuit board 5, and the circuit board 5 is located between the two magnet holders 202 and 402. Since the first magnet 201, the second magnet 401, and the magnetic sensor element 1 are respectively positioned at the center positions of the first magnet holder 202, the second magnet holder 402, and the circuit board 5, the centers of the first magnet 201, the second magnet 401, and the magnetic sensor element 1 are aligned on a straight line. The magnetic sensor assembly 100 after installation is shown in fig. 5.
For example, based on the above technical solution, it is optional that the plane of the bottom electrode 101 of the magneto-sensitive cell 31 shown in fig. 2 is parallel to the plane of the film layer of the multilayer thin-film structure 1a, and the plane of the top electrode 109 of the magneto-sensitive cell 31 is parallel to the plane of the film layer of the multilayer thin-film structure 1 a. In this embodiment, the optional magneto-sensitive element is a tunnel magnetoresistive element. The optional bottom electrode 101 is located on the substrate 3, the multilayer thin film structure 1a is located on the bottom electrode 101, the top electrode 109 is located on the multilayer thin film structure 1a, and the bottom electrode 101 and the top electrode 109 of the magneto-sensitive unit 31 are located on the upper side and the lower side of the film layer structure of the multilayer thin film structure 1 a. In this case, the magneto-sensitive element 31 is a magneto-sensitive thin film structure based on the tunnel magnetoresistance principle. In other embodiments, the optional magnetic sensing unit is constructed based on other magnetic resistance principles.
As shown in FIG. 6, the plane of the bottom electrode 101 of the magneto-sensitive cell 31 is perpendicular to the plane of the film layer of the multi-layer film structure 1a, and the plane of the top electrode 109 of the magneto-sensitive cell 31 is perpendicular to the plane of the film layer of the multi-layer film structure 1 a. In this embodiment, the optional magneto-sensitive element is a giant magneto-resistive element. The optional bottom electrode 101, the multilayer thin-film structure 1a, and the top electrode 109 are all located on the substrate 3, and the seed layer 102 of the multilayer thin-film structure 1a is located on the substrate 3, specifically, the bottom electrode 101 and the top electrode 109 of the magnetosensitive unit 31 are located on the left and right sides of the film layer structure of the multilayer thin-film structure 1 a. In this case, the magneto-sensitive unit 31 is a magneto-sensitive thin film structure formed based on the giant magneto-resistance principle.
In this embodiment, the seed layer 102 is composed of a multilayer film of Ta or Ru, and the purpose thereof is to grow the antiferromagnetic layer 103 in accordance with a desired lattice for lattice matching, thereby reducing defects. Above the antiferromagnetic layer 103 is an exchange-bias layer 1b made up of layers 104, 105 and 106 with a spacer layer 105 between the ferromagnetic layer 104 and the pinned layer 106, with the structure that the magnetic moment of the pinned layer 106 will be fixed in-plane with the orientation shown at 111. Above the pinning layer 106 is a spacer layer 107, made of a metal such as copper, gold. Above the isolation layer 107 is a free layer 108, which is made of one or more of Ni, Fe, Co, and B.
In this embodiment, two electrodes 101 and 109 are located on both sides of the multilayer thin-film structure 1 a. The electrodes 101 to 109 constitute a minimum unit of the magneto-sensitive element, and a plurality of the minimum units are connected in series and in parallel to constitute the magneto-sensitive element. The protective layer 110 is disposed on the top of the entire film to prevent the film from being damaged and oxidized. When there is no external magnetic field, the magnetic moment direction of the magneto-sensitive unit 31 is parallel to the magnetic moment direction 112 of the free layer 108 and is perpendicular to the film plane, when there is a magnetic field in the same direction as or opposite to the arrow 111, the magnetic moment direction 112 of the free layer 108 will deviate, and according to the magnetoresistance principle, the resistance value of the multilayer thin film structure 1a between the two electrodes 101 and 109 will change, and the magnitude of the external magnetic field can be measured according to the resistance value.
For example, on the basis of the above technical solution, the circuit structure of the magnetic sensing element shown in fig. 7 and fig. 8 may be selected as a full-bridge structure, four bridge arms of the full-bridge structure are respectively formed by connecting a plurality of magnetic sensing units in series and in parallel, the magnetic moment directions of the pinning layers of each magnetic sensing unit in the bridge arms are consistent, the magnetic moment directions of the pinning layers of the sensitive units of two bridge arms in the four bridge arms, which are crossed and corresponding to each other, are consistent, and the magnetic moment directions of the pinning layers of the sensitive units of two adjacent bridge arms in the four bridge arms are.
The solid arrows in fig. 7 and 8 represent the magnetic moment direction of the pinned layer and the dashed arrows represent the magnetic moment direction of the free layer. As shown in fig. 7, the bridge arms 501 and 504 are crossed and correspond to each other, and the bridge arms 502 and 503 are crossed and correspond to each other in the full-bridge structure, in which the bridge arm 501 is adjacent to the bridge arms 502 and 503, respectively, and the bridge arm 504 is adjacent to the bridge arms 502 and 503, respectively. As shown in fig. 8, the bridge arms 601 and 604 and the bridge arms 602 and 603 are crossed and correspond to each other in the full-bridge structure, the bridge arm 601 is adjacent to the bridge arms 602 and 603, respectively, and the bridge arm 604 is adjacent to the bridge arms 602 and 603, respectively.
For any one bridge arm, the magnetic moment directions of the pinning layers of the magnetosensitive units of each bridge arm are consistent, the magnetic moment directions of the pinning layers of the magnetosensitive units of the two bridge arms such as 501 and 504 (or the bridge arms 601 and 604) which are crossed correspondingly in the full-bridge structure are consistent and are both-X-axis directions, and the magnetic moment directions of the pinning layers of the magnetosensitive units of the two bridge arms such as 502 and 503 (or the bridge arms 602 and 603) which are crossed correspondingly in the full-bridge structure are consistent and are both + X-axis directions.
The resistance value expression of the magneto-sensitive element of the full-bridge structure formed by the magneto-sensitive units is as follows:
a and B are constants related to the MR value and the minimum resistance value of the multilayer thin film structure 1a, and theta is an angle between the free layer 108 and the pinned layer 106.
When the applied magnetic field is zero, θ is 90 degrees as shown in FIG. 7, and the magnetic moment of the free layer is perpendicular to the magnetic moment of the pinned layer.
When the applied magnetic field is not zero, θ is not 90 degrees as shown in fig. 8. Assuming that the external magnetic field direction to be measured is the direction of arrow 605 in the figure, the magnetic field direction to be measured is the same as the pinning layer direction of bridge arm 602/603. Because the magnetic moment of the pinning layer is relatively strong and cannot be interfered by an external magnetic field, the direction of the pinning layer cannot be changed; the magnetic moment of the free layer can change along with the interference of an external magnetic field, and the deflection direction of the free layer is inclined to be the same as the direction of the external magnetic field. When a sufficiently large external magnetic field is applied, such as thousands of gauss, the magnetic moment direction of the free layer will be exactly the same as the external measured magnetic field direction.
In the tunnel magnetoresistive sensor cell shown in fig. 2, in the magnetic sensor element having the full-bridge structure, the top electrodes 109 of the magnetic sensor cells of the arm 501 and the arm 504 (or the arms 601 and 604) are in contact with the substrate 3, the bottom electrodes 101 are in contact with the protective layer 110, the bottom electrodes 101 of the magnetic sensor cells of the arm 502 and the arm 503 (or the arms 602 and 603) are in contact with the substrate 3, and the top electrodes 109 are in contact with the protective layer 110. Multilayer film structure 1a of leg 501/504 is in a completely reverse order of film lamination with multilayer film structure 1a of leg 502/503, and multilayer film structure 1a of leg 601/604 is in a completely reverse order of film lamination with multilayer film structure 1a of leg 602/603. The following calculations are made to illustrate the principle of the tunnel magnetoresistive sensing element in a full-bridge configuration as shown in fig. 8:
in the figure, the resistances of the bridge arms 601-604 are respectively R1-R4, R1 is completely the same as R4, and R2 is completely the same as R3. Under the influence of an external measured magnetic field, the included angle between the magnetic moment direction of the free layer and the magnetic moment direction of the pinned layer in the bridge arms 601 and 604 is theta, and the included angle between the magnetic moment direction of the free layer and the magnetic moment direction of the pinned layer in the bridge arms 602 and 603 is 180 DEG-theta, so that the output characteristics are deduced as follows:
where B is a constant and Vcc is the supply voltage. As can be seen from the above equation, the output voltage depends on the variation of θ.
Fig. 9 is test data of the magnetic sensor of the present embodiment, in which the broken line and the solid line correspond to R1 and R2 of the above formula, respectively, and the dotted line corresponds to the output voltage of the full bridge, in which the deflection angle θ affects the resistance value from which the output voltage can be determined. It can be seen that the output voltage varies substantially linearly within the range of plus or minus 1000 Gs. Fig. 10 shows measured data of a conventional magnetic sensor, in which the dashed line and the solid line correspond to R1 and R2, respectively, and the dotted line corresponds to the output voltage of the full bridge, and it can be seen from the figure that the output voltage changes substantially linearly in the range of plus and minus 100Gs, but when the magnetic field is large, especially up to 200Gs, the output voltage does not change substantially, and at this time, the magnetic sensor reaches a saturation state, and the measurement of the external measured magnetic field will fail.
Clearly, the prior art provides magnetic sensing elements that can only measure magnetic fields within 200 Gs. The magnetic sensing element provided by the embodiment adopts the external magnets, namely the first magnet structure and the second magnet structure, the bias magnetic field generated by the external magnets at the magnetic sensing element has the same direction as the magnetic moment of the free layer of the magnetic sensing element, so that the change of theta can be reduced, the magnetic sensing element is more difficult to saturate, and as can be seen from fig. 9, the linear range can be increased to be close to 1000Gs, the effect of increasing the dynamic range is achieved, and the magnetic sensing element can detect a larger magnetic field.
In the giant magnetoresistive sensitive cell GMR shown in fig. 6, the top electrodes 109 of the magnetosensitive cells of the bridge 501 and the bridge 504 (or the bridges 601 and 604) are located on the left side of the multilayer thin-film structure 1a, and the bottom electrodes 101 are located on the right side of the multilayer thin-film structure 1a in the magnetosensitive element of the full-bridge structure. The top electrodes 109 of the magnetosensitive cells of bridge arm 502 and bridge arm 503 (or bridge arms 602 and 603) are located on the right side of multilayer thin-film structure 1a, and the bottom electrodes 101 are located on the left side of multilayer thin-film structure 1 a. Multilayer film structure 1a of leg 501/504 is in a completely reverse order of film lamination with multilayer film structure 1a of leg 502/503, and multilayer film structure 1a of leg 601/604 is in a completely reverse order of film lamination with multilayer film structure 1a of leg 602/603.
For GMR, the resistances of the bridge arms 601-604 are respectively R1-R4, R1 and R4 are completely the same, and R2 and R3 are completely the same. There is the following guidance:
R1＝R4＝C-D*cos(θ)
R2＝R3＝C+D*cos(θ)
wherein C and D are constants related to the MR value and the minimum resistance value of the multilayer thin film structure, and theta is the included angle between the free layer and the pinning layer, and the output characteristic is similar to that of the tunnel magnetoresistive sensitive element and is not repeated.
In other embodiments, the circuit structure of the magnetic sensor element may be a half-bridge structure, two bridge arms of the half-bridge structure are formed by connecting a plurality of magnetic sensor units in series and parallel, the magnetic moment directions of the pinning layers of each magnetic sensor unit in the bridge arms are the same, and the magnetic moment directions of the pinning layers of the magnetic sensor units of the two bridge arms are opposite.
It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (7)
1. A high dynamic range magnetic sensor assembly, comprising: the circuit board comprises a first magnet structure, a circuit board and a magnetic sensing element arranged on the circuit board, wherein the first magnet structure is positioned on one side of the circuit board, a first connecting line formed by a central point of a first magnetic pole of the first magnet structure and a central point of the magnetic sensing element is vertical to the plane of the first magnetic pole, a central point of a second magnetic pole of the first magnet structure is positioned on an extension line of the first connecting line, and the sensitive direction of the magnetic sensing element is positioned in the plane of the magnetic sensing element and is vertical to the first connecting line;
the magnetic sensing element comprises at least one magnetic sensing unit, the magnetic sensing unit comprises a bottom electrode, a top electrode and a multilayer thin film structure positioned between the bottom electrode and the top electrode, the multilayer thin film structure comprises a seed layer, an anti-ferromagnetic layer, an exchange bias layer, an isolation layer and a free layer which are sequentially stacked, the exchange bias layer comprises a ferromagnetic layer, a spacer layer and a pinning layer, and the magnetic moment direction of the pinning layer is in the plane of the magnetic sensing element; when no external magnetic field exists, the direction of the magnetic moment of the free layer is vertical to the plane of the magnetic sensitive element, and when the external magnetic field is applied, the direction of the magnetic moment of the free layer deviates.
2. The high dynamic range magnetic sensor assembly of claim 1, further comprising: the circuit board comprises a first magnet structure, a second magnet structure, a first connecting wire and a second magnet structure, wherein the first magnet structure is arranged on one side of the circuit board and deviates from the first magnet structure, the central point of the first magnetic pole of the second magnet structure and the central point of the second magnetic pole are both arranged on the extension line of the first connecting wire, the second magnetic pole of the second magnet structure faces the circuit board, the second magnet structure is arranged opposite to the first magnet structure, and the second magnetic pole of the second magnet structure is opposite to the first magnetic pole of the first magnet structure in polarity.
3. The high dynamic range magnetic sensor assembly of claim 2, wherein said first magnet structure comprises a first magnet and a first magnet holder, said first magnet being embedded in said first magnet holder; the second magnet structure comprises a second magnet and a second magnet seat, and the second magnet is embedded in the second magnet seat;
the first magnet and the second magnet have the same shape, and the same shape is a cylinder shape, a cuboid shape, a frustum shape or a circular truncated cone shape;
the first magnet and the second magnet are made of the same material, and the same material is samarium cobalt, neodymium iron boron, alnico or ferrite.
4. The high dynamic range magnetic sensor assembly of claim 1, wherein said bottom electrode of said magneto-sensitive cell is in a plane parallel to a plane of a layer of said multilayer thin film structure, and said top electrode of said magneto-sensitive cell is in a plane parallel to a plane of a layer of said multilayer thin film structure; alternatively, the first and second electrodes may be,
the plane of the bottom electrode of the magnetic sensing unit is perpendicular to the plane of the film layer of the multilayer film structure, and the plane of the top electrode of the magnetic sensing unit is perpendicular to the plane of the film layer of the multilayer film structure.
5. The large dynamic range magnetic sensor assembly of claim 1, wherein said magnetic sensing element has a half-bridge configuration, and both legs of said half-bridge configuration are formed by connecting a plurality of said magnetic sensing cells in series and parallel, wherein the pinned layers of each magnetic sensing cell of said legs have the same magnetic moment direction, and the pinned layers of the magnetic sensing cells of said two legs have the opposite magnetic moment directions.
6. The large dynamic range magnetic sensor assembly of claim 1, wherein the magnetic sensor element has a circuit structure of a full bridge, four legs of the full bridge are each formed by connecting a plurality of said magnetic sensor cells in series and parallel, the pinned layers of each magnetic sensor cell in the legs have the same magnetic moment direction, the pinned layers of the magnetic sensor cells in two legs of the four legs that are crossed and corresponding have the same magnetic moment direction, and the pinned layers of the magnetic sensor cells in two adjacent legs of the four legs have the opposite magnetic moment directions.
7. The high dynamic range magnetic sensor assembly of claim 1, wherein said magneto-sensitive element is a giant magneto-resistive element or a tunnel magneto-resistive element.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112014778A (en) * | 2020-08-24 | 2020-12-01 | 歌尔微电子有限公司 | Micro-electro-mechanical system magnetoresistive sensor, sensor single body and electronic equipment |
| CN114034932A (en) * | 2021-11-04 | 2022-02-11 | 之江实验室 | Method for measuring planar Hall resistance of ferrimagnetic perpendicular anisotropic film |
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2019
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112014778A (en) * | 2020-08-24 | 2020-12-01 | 歌尔微电子有限公司 | Micro-electro-mechanical system magnetoresistive sensor, sensor single body and electronic equipment |
| CN112014778B (en) * | 2020-08-24 | 2023-11-07 | 歌尔微电子有限公司 | Magneto-resistive sensor of micro-electromechanical system, sensor unit and electronic equipment |
| CN114034932A (en) * | 2021-11-04 | 2022-02-11 | 之江实验室 | Method for measuring planar Hall resistance of ferrimagnetic perpendicular anisotropic film |
| CN114034932B (en) * | 2021-11-04 | 2022-04-19 | 之江实验室 | Method for measuring planar Hall resistance of ferrimagnetic perpendicular anisotropic film |
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