Micro-electromechanical system differential magnetic sensor, sensor unit and electronic device

Abstract

Disclosed are a micro-electromechanical system differential magnetic sensor, a sensor unit and an electronic device. The micro-electromechanical system differential magnetic sensor comprises: a first magnetic resistor; a first magnetic source; and a second magnetic source, wherein the first magnetic source and the second magnetic source are respectively located on both sides of the first magnetic resistor, the magnetization directions of the first magnetic source and the second magnetic source are opposite, so as to form a differential magnetic field at the first magnetic resistor, the first magnetic resistor, the first magnetic source and the second magnetic source are formed on the same device plane, and the first magnetic resistor can move relative to the first magnetic source and the second magnetic source.

Description

Technical Field

[0001] The present specification relates to the technical field of micro-electromechanical system (MEMS) sensors, and more specifically, to a micro-electromechanical system differential magnetic sensor, a sensor unit, and an electronic device. Background Art

[0002] The MEMS sensor may include a MEMS capacitive sensor and a magnetic sensor. In the MEMS capacitive sensor, a diaphragm and a back plate are provided. When the diaphragm vibrates, the capacitance between the diaphragm and the back plate changes. By detecting this capacitance change, the vibration of the diaphragm is determined. In the MEMS magnetoresistive sensor, a magnetic source and a magnetoresistive are provided. When the relative positions of the magnetic source and the magnetoresistive change, the magnetic field applied to the magnetoresistive also changes. The change in the magnetic field causes the resistance value of the magnetoresistive to change.

[0003] MEMS sensors can be used as MEMS microphones, MEMS accelerometers, etc. Summary of the invention

[0004] The embodiments of this specification provide a new technical solution for a micro-electromechanical system differential magnetic sensor.

[0005] According to a first aspect of the present specification, a micro-electromechanical system differential magnetic sensor is provided, comprising: a first magnetic resistor; a first magnetic source; and a second magnetic source, wherein the first magnetic source and the second magnetic source are respectively located on both sides of the first magnetic resistor, wherein the magnetization directions of the first magnetic source and the second magnetic source are opposite to form a differential magnetic field at the first magnetic resistor, wherein the first magnetic resistor, the first magnetic source and the second magnetic source are formed on the same device plane, and wherein the first magnetic resistor can move relative to the first magnetic source and the second magnetic source.

[0006] According to a second aspect of the present specification, a sensor unit is provided, including a substrate, a micro-electromechanical system differential magnetic sensor according to an embodiment, and an integrated circuit chip, wherein the micro-electromechanical system differential magnetic sensor and the integrated circuit chip are arranged on the substrate.

[0007] According to a third aspect of the present specification, there is provided an electronic device including the sensor unit according to the embodiment.

[0008] In various embodiments, the manufacturing process of a micro-electromechanical system differential magnetic sensor may be simplified.

[0009] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the embodiments of the present specification.

[0010] In addition, any embodiment in the embodiments of this specification does not need to achieve all the above-mentioned effects.

[0011] Other features and advantages of the embodiments of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0013] Figure 1 FIG. 4 shows a schematic magnetic field line distribution of the micro-electromechanical system differential magnetic sensor according to the first embodiment.

[0014] Figure 2 FIG. 1 is a schematic diagram showing the change of magnetic field strength to which the magnetic resistance is subjected in the micro-electromechanical system differential magnetic sensor according to the first embodiment.

[0015] Figure 3 FIG. 4 shows a schematic structure of a micro-electromechanical system differential magnetic sensor according to a second embodiment.

[0016] Figure 4 FIG. 4 shows a schematic magnetic field line distribution of a micro-electromechanical system differential magnetic sensor according to the third embodiment.

[0017] Figure 5 FIG. 1 is a schematic diagram showing the change of magnetic field strength to which the magnetic resistance is subjected in the micro-electromechanical system differential magnetic sensor according to the third embodiment.

[0018] Figure 6 A schematic structure of a micro-electromechanical system differential magnetic sensor according to a fourth embodiment is shown.

[0019] Figure 7 A schematic structure of a micro-electromechanical system differential magnetic sensor according to a fifth embodiment is shown.

[0020] Figure 8 A schematic diagram showing a sensor cell according to a sixth embodiment is shown.

[0021] Fig. 9 A schematic diagram showing an electronic device according to a seventh embodiment is shown. DETAILED DESCRIPTION

[0022] Various exemplary embodiments will now be described in detail with reference to the accompanying drawings.

[0023] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0024] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0025] Hereinafter, various embodiments and examples of the present specification are described with reference to the accompanying drawings.

[0026] MEMS magnetic sensors usually adopt a non-differential magnetic field structure. Compared with MEMS magnetic sensors that adopt non-differential magnetic fields, MEMS magnetic sensors that adopt differential magnetic fields can have higher sensitivity, wider linear range, etc. At present, this MEMS differential magnetic sensor adopts a non-coplanar structure to arrange magnetic resistors and permanent magnet pairs that provide differential magnetic fields. The inventors found that in this MEMS differential magnetic sensor with a non-planar structure, it is necessary to accurately position the magnetic resistors and permanent magnet pairs. In this case, it will bring great challenges to the performance optimization and production yield of the MEMS differential magnetic sensor.

[0027] Therefore, it is proposed here to set the magnetic resistance and the magnetic source / permanent magnet providing the differential magnetic field in a coplanar structure, so as to improve the mass production and yield of the micro-electromechanical system differential magnetic sensor.

[0028] In one embodiment, a micro-electromechanical system differential magnetic sensor includes: a first magnetic resistor; a first magnetic source; and a second magnetic source. The first magnetic source and the second magnetic source are respectively located on both sides of the first magnetic resistor. The magnetization directions of the first magnetic source and the second magnetic source are opposite to each other, so as to form a differential magnetic field at the first magnetic resistor. The first magnetic resistor, the first magnetic source, and the second magnetic source are formed on the same device plane. The first magnetic resistor can move relative to the first magnetic source and the second magnetic source.

[0029] Here, on the one hand, this structure using a differential magnetic field can provide higher sensitivity, linear range, etc. On the other hand, due to the coplanar structure, it is easier to set the position of the magnetic resistance and the magnetic source, so that performance optimization can be performed more easily. Such a micro-electromechanical system differential magnetic sensor can have higher mass production and yield. In addition, this can also give designers greater design freedom. Those skilled in the art should understand that the "first magnetic resistance, the first magnetic source, and the second magnetic source are formed on the same device plane" here means that when stationary, in the absence of external force (for example, in the absence of external pressure, or in the absence of a vacuum formed in the sealed cavity in the sensor), the first magnetic resistance, the first magnetic source, and the second magnetic source are on the same device plane.

[0030] For example, the first magnetic source and the second magnetic source are permanent magnets. They can be permanent magnet magnetic films.

[0031] In one embodiment, the first magnetic resistor can move between the first magnetic source and the second magnetic source relative to the first magnetic source and the second magnetic source in the plane of the device. It should be understood by those skilled in the art that the relative movement of the magnetic resistor and the magnetic source includes the following situations. In the first situation, the magnetic resistor is stationary and the magnetic source moves. In the second situation, the magnetic resistor moves and the magnetic source is stationary. In the third situation, both the magnetic resistor and the magnetic source move, but the relative position of the magnetic resistor and the magnetic source changes.

[0032] In this embodiment, the movement of the magnetic resistor relative to the magnetic source is also located in the same plane. This structure is conducive to controlling the range of movement, thereby avoiding damage to the moving parts of the sensor.

[0033] In one embodiment, the micro-electromechanical system differential magnetic sensor further includes: a first device portion, a second device portion, and a third device portion located in the same device layer. The second device portion is located between the first device portion and the third device portion, and is movable between the first device portion and the third device portion within the device plane relative to the first device portion and the third device portion. The first magnetic source is located on the first device portion, the first magnetic resistance is located on the second device portion, and the second magnetic source is located on the third device portion.

[0034] For example, the second device portion is a cantilever beam located between the first device portion and the second device portion, and the first magnetic resistor is located at the end of the cantilever beam. The end of the cantilever beam refers to the portion from at least 2 / 3 of the suspended portion of the cantilever beam to the end. Since the end of the cantilever beam can achieve a larger vibration amplitude than the front end of the cantilever beam, this is conducive to improving the sensitivity of the sensor.

[0035] Optionally, the second device part may also be a beam with both ends fixed on the support member, and the first magnetic resistor may be located in the middle section of the beam. For example, the beam is an elastic beam that can move under the action of an external physical signal.

[0036] In another embodiment, the first device part and the second device part are cantilever beams, and the second device part is a beam located between the first device part and the second device part. The first magnetic source and the second magnetic source are located at the end of the cantilever beam. In this structure, since the magnetic source can be a permanent magnet film, there is no current in the magnetic source. In this way, the movement of the magnetic source will not generate current noise. In addition, since the magnetic source does not need to be powered by a current line, it is not necessary to arrange a current line on the cantilever beam, thereby avoiding interference caused by this part of the current line. In addition, the magnetic resistor can be located in a relatively static position. In this way, the current in the magnetic resistor will not cause large noise and / or power consumption loss due to vibration.

[0037] In addition, the micro-electromechanical system differential magnetic sensor further includes: a second magnetic resistor, a third magnetic source, and a fourth magnetic source respectively arranged in the same manner as the first magnetic resistor, the first magnetic source, and the second magnetic source. The magnetization directions of the third magnetic source and the fourth magnetic source are respectively opposite to the magnetization directions of the first magnetic source and the second magnetic source. The first magnetic resistor and the second magnetic resistor move in the same manner to form a differential resistor.

[0038] In another embodiment, the first magnetoresistance can be shifted in a direction normal to the plane of the device.

[0039] The embodiments disclosed herein will be described in detail below with reference to the accompanying drawings.

[0040] Figure 1 FIG. 4 shows a schematic magnetic field line distribution of a micro-electromechanical system differential magnetic sensor according to the first embodiment. Figure 1 As shown, the magnetic field direction of the permanent magnet magnetic sources MS1 and MS2 is in the Z direction. The magnetic field direction of the magnetic source MS1 is in the +Z direction, and the magnetic field direction of the magnetic source MS2 is opposite to the magnetic field direction of the magnetic source MS1, which is in the -Z direction. Figure 1 As shown by the dotted line, the magnetic sources MS1 and MS2 generate a differential magnetic field between them. The magnetic sources MS1 and MS2 are arranged to be symmetrically located on both sides of the magnetic resistor MR1. The magnetic sources MS1, MS2 and the magnetic resistor MR1 are coplanar. For example, the magnetic sources MS1, MS2 and the magnetic resistor MR1 are arranged in the same device layer.

[0041] exist Figure 1 In the figure, the pinning direction of the magnetoresistance MR1 is the +Z direction indicated by arrow 1. The magnetoresistance MR1 moves between the magnetic sources MS1 and MS2, as indicated by arrow 5. The magnetoresistance MR1 includes a free layer 2, a spacer layer 3 and a pinning layer 4. The magnetoresistance MR1 is sensitive to the change of the magnetic flux density BZ in the Z direction. The sensitivity SR of the magnetoresistance MR1 is SR = (dR / dBZ)*R, where R is the resistance value of the magnetoresistance MR1.

[0042] Figure 2 FIG. 1 is a schematic diagram showing the change of magnetic field intensity to which the magnetoresistance is subjected in the micro-electromechanical system differential magnetic sensor according to the first embodiment.

[0043] like Figure 2 As shown, reference numeral 7 indicates the position of magnetic source MS1, which is also the boundary of the left magnetic field. Reference numeral 8 indicates the position of magnetic source MS2, which is also the boundary of the side magnetic field. The main axis magnetic field generated by magnetic source MS1 is shown in curve 9, the main axis magnetic field generated by magnetic source MS2 is shown in curve 10, and the total main axis magnetic field component (magnetic induction intensity) is shown in curve 11. Therefore, such a structure has a higher magnetic field spatial gradient, that is, the magnetic field sensitivity SB = dBZ / dX.

[0044] When the magnetic resistance MR1 and the magnetic source pair MS1 and MS2 move relative to each other in the X direction (+ / -X) (in-plane vibration), the mechanical sensitivity to sensitive external physical signals (such as sound pressure, acceleration, angular velocity, pressure, etc.) is SM=dX / dP, where P is the external physical signal.

[0045] like Figure 2 As shown, the sensor with such structure can have improved magnetic field gradient (sensitivity) and wider linear range.

[0046] Figure 3 FIG. 4 shows a schematic structure of a micro-electromechanical system differential magnetic sensor according to a second embodiment. Figure 3 As shown, the magnetic resistor MR1 is located between the magnetic sources MS1 and MS2. The magnetic fields of the magnetic sources MS1 and MS2 are in opposite directions. The magnetic resistor MR2 and the magnetic sources MS3 and MS4 are arranged similarly. The magnetic fields of the magnetic sources MS3 and MS4 are in opposite directions to those of the magnetic sources MS1 and MS2, respectively.

[0047] When the magnetic resistors MR1 ​​and MR2 vibrate together relative to the magnetic sources MS1, MS2, MS3, and MS4, the magnetic resistors MR1 ​​and MR2 can form differential magnetic resistors, that is, the resistance value of one of the magnetic resistors MR1 ​​and MR2 becomes larger and the resistance value of the other becomes smaller. The two sets of magnetic resistors and magnetic sources can be placed at different positions of the same moving part.

[0048] However, the magnetoresistance MR1 and MR2 are used to form a Wheatstone full bridge circuit. In this way, the sensitivity of the sensor can be S=VB*SR*SB*SM, where VB is the bias voltage of the Wheatstone bridge.

[0049] Permanent magnets with opposite magnetization directions can be manufactured by bonding methods, such as wafer-level bonding and die-level bonding.

[0050] Figure 4 FIG. 4 shows a schematic magnetic field line distribution of a micro-electromechanical system differential magnetic sensor according to the third embodiment.

[0051] The magnetic field direction of the permanent magnet magnetic sources MS1' and MS2' is in the Z direction. The magnetic field direction of the magnetic source MS1' is in the +Z direction, and the magnetic field direction of the magnetic source MS2' is opposite to the magnetic field direction of the magnetic source MS1', which is in the -Z direction. Figure 1 As shown by the dashed line, the magnetic sources MS1' and MS2' generate a differential magnetic field between them. The magnetic sources MS1' and MS2' are arranged to be symmetrically located on both sides of the magnetic resistor MR1'. The magnetic sources MS1', MS2' and the magnetic resistor MR1' are coplanar. For example, the magnetic sources MS1', MS2' and the magnetic resistor MR1' are arranged in the same device layer.

[0052] The pinning direction of the magnetoresistance MR1' is the +X direction indicated by the arrow 12. The magnetoresistance MR1' moves in the Z direction (+ / -Z, out-of-plane vibration) along the normal direction of the device plane, as indicated by the arrow 16. The magnetoresistance MR1' includes a free layer 13, a spacer layer 14 and a pinned layer 15. The magnetoresistance MR1' is sensitive to the change of the magnetic flux density BX in the X direction. The sensitivity SR of the magnetoresistance MR1' is SR = (dR / dBX) * R, where R is the resistance value of the magnetoresistance MR1'.

[0053] Figure 5 FIG. 1 is a schematic diagram showing the change of magnetic field strength to which the magnetic resistance is subjected in the micro-electromechanical system differential magnetic sensor according to the third embodiment.

[0054] like Figure 5 As shown, the X-direction magnetic fields generated by magnetic sources MS1' and MS2' are the same, as shown by curve 18. The total X-direction magnetic field component (magnetic induction intensity) is twice the X-direction magnetic field component generated by magnetic source MS1' or MS2', as shown by curve 19. Therefore, such a structure has a higher magnetic field spatial gradient.

[0055] When the magnetic resistance MR1 and the magnetic source pair MS1 and MS2 move relative to each other in the Z direction (+ / -Z) (in-plane vibration), the mechanical sensitivity to sensitive external physical signals (such as sound pressure, acceleration, angular velocity, pressure, etc.) is SM=dZ / dP, where P is the external physical signal.

[0056] like Figure 5 As shown, the sensor with such structure can have improved magnetic field gradient (sensitivity) and wider linear range.

[0057] Figure 6 A schematic structure of a micro-electromechanical system differential magnetic sensor according to a fourth embodiment is shown.

[0058] like Figure 6 As shown, magnetic sources MS1 and MS2 are arranged on a fixed support portion 22 of a device layer of a micro-electromechanical system differential magnetic sensor. A magnetoresistance MR1 is arranged on a cantilever beam 21. The magnetoresistance MR1 is located at the end of the cantilever beam 21 and between the magnetic sources MS1 and MS2. The magnetic sources MS1 and MS2 may be symmetrical with respect to the magnetoresistance MR1.

[0059] Figure 7 A schematic structure of a micro-electromechanical system differential magnetic sensor according to a fifth embodiment is shown.

[0060] like Figure 7As shown, magnetic sources MS1 and MS2 are respectively arranged on cantilever beams 23 and 24. Magnetic resistor MR1 is arranged on beam 25. Both ends of beam 25 are fixedly supported on fixed support portion 26 of device layer. Magnetic sources MS1 and MS2 are respectively located at the end of cantilever beams 23 and 24. Magnetic resistor MR1 is located between magnetic sources MS1 and MS2. Magnetic sources MS1 and MS2 can be symmetrical with respect to magnetic resistor MR1.

[0061] Figure 8 A schematic diagram showing a sensor cell according to a sixth embodiment is shown.

[0062] like Figure 8 As shown, the sensor unit 30 includes a substrate 31 , the above-described micro-electromechanical system differential magnetic sensor 32 , and an integrated circuit chip 33 . The micro-electromechanical system differential magnetic sensor 32 and the integrated circuit chip 33 are disposed on the substrate 31 .

[0063] The sensor cell 30 also includes leads 34 that connect the micro-electromechanical system differential magnetic sensor 32 to the integrated circuit chip 33 , and connect the micro-electromechanical system differential magnetic sensor 32 and the integrated circuit chip 33 to pads 35 and interconnection lines 36 in the substrate 31 .

[0064] Fig. 9 A schematic diagram showing an electronic device according to a seventh embodiment is shown.

[0065] like Fig. 9 As shown, the electronic device 40 may include Figure 8 The sensor unit 41 is shown. The electronic device 40 may be a mobile phone, a tablet computer, a wearable device, etc.

[0066] The above is only a specific implementation of the embodiments of this specification. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the embodiments of this specification. These improvements and modifications should also be regarded as the protection scope of the embodiments of this specification.

Claims

1. A micro-electromechanical system differential magnetic sensor, comprising: First magnetic resistance; a first magnetic source; as well as The second magnetic source, The first magnetic source and the second magnetic source are located on both sides of the first magnetic resistor, respectively. The first magnetic source and the second magnetic source have opposite magnetization directions to form a differential magnetic field at the first magnetic resistance. The first magnetic resistor, the first magnetic source and the second magnetic source are formed on the same device plane, and the magnetic field directions of the first magnetic source and the second magnetic source are the normal direction Z direction of the device plane, and wherein the first magnetic resistor is movable relative to the first magnetic source and the second magnetic source, The first magnetic resistor can move along the normal direction of the device plane, and the pinning direction of the first magnetic resistor is the +X direction in the device plane.

2. The micro-electromechanical system differential magnetic sensor according to claim 1, wherein: The first magnetic source and the second magnetic source are permanent magnets.

3. The micro-electromechanical system differential magnetic sensor according to claim 1 or 2, further comprising: a first device portion, a second device portion and a third device portion located in the same device layer, wherein the second device portion is located between the first device portion and the third device portion, The first magnetic source is located on the first device portion, the first magnetic resistance is located on the second device portion, and the second magnetic source is located on the third device portion.

4. The micro-electromechanical system differential magnetic sensor according to claim 3, wherein: The second device portion is a cantilever beam located between the first device portion and the third device portion, and Wherein, the first magnetic resistance is located at the end section of the cantilever beam.

5. The micro-electromechanical system differential magnetic sensor according to claim 3, wherein: The second device part is a beam with both ends fixed on the support member, and Wherein, the first magnetic resistance is located in the middle section of the beam.

6. The micro-electromechanical system differential magnetic sensor according to claim 3, wherein: The first device portion and the third device portion are cantilever beams, the second device portion is a beam located between the first device portion and the third device portion, and Wherein, the first magnetic source and the second magnetic source are located at the end section of the cantilever beam.

7. The micro-electromechanical system differential magnetic sensor according to claim 1 or 2, further comprising: a second magnetic resistance, a third magnetic source and a fourth magnetic source respectively arranged in the same manner as the first magnetic resistance, the first magnetic source and the second magnetic source, The magnetization directions of the third magnetic source and the fourth magnetic source are opposite to the magnetization directions of the first magnetic source and the second magnetic source, respectively. The first magnetic resistor and the second magnetic resistor move in the same way to form a differential resistor.

8. A sensor unit, comprising a substrate, a micro-electromechanical system differential magnetic sensor according to claim 1, and an integrated circuit chip, wherein: The micro-electromechanical system differential magnetic sensor and the integrated circuit chip are arranged on the substrate. 9 . An electronic device comprising the sensor unit according to claim 8 .

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