A magnetic field regulating device and a method for manufacturing the same

Abstract

A magnetic field regulating device and a preparation method thereof, the magnetic field regulating device comprising: a composite magnetic element pair, the composite magnetic elements in the composite magnetic element pair are arranged at intervals, the composite magnetic element comprises a ferromagnetic layer and a piezoelectric layer, and the piezoelectric layer is electrically connected to an external voltage source. The composite magnetic element of the present invention is a composite structure of piezoelectric material and ferromagnetic material, the magnetic permeability of the magnetic material is changed by the electrostrictive effect of the piezoelectric material, the local magnetic field is regulated by the guiding effect of the magnetic material on the external magnetic field, and the magnetic field of the micro-region can be continuously and real-time regulated by changing the voltage. The composite magnetic element can be made by semiconductor technology, and has the advantages of extremely low power consumption, low price and small size.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic field detection, and in particular relates to a magnetic field regulating device and a preparation method thereof. Background Art

[0002] Magnetic field detection has a wide range of applications in the field of sensing. In the test environment of many magnetic field sensors, it is necessary to control the direction of the external magnetic field to be measured. For example, in full-bridge testing, in order to form a full-bridge differential output, the direction of the magnetic field needs to be changed before testing. Another example is in closed-loop magnetic field testing. Since magnetic field sensors are usually only sensitive to magnetic fields in one direction, it is necessary to adjust the external magnetic field to other directions to obtain a false zero magnetic field in order to achieve closed-loop testing.

[0003] Currently, there are very limited means to change the distribution of the magnetic field (magnetic field direction). The more conventional method is to use electromagnets to generate vector magnetic fields to change the local magnetic field distribution, but this method requires the use of coils, which have the problems of large size and high energy consumption. Another way is to use magnetic materials with high magnetic permeability to change the distribution of the local magnetic field. Compared with the method of using electromagnets to change the local magnetic field, using magnetic materials to control the direction and intensity of the magnetic field does not have the problem of energy consumption. However, after the preparation of traditional magnetic materials, their performance is fixed, and the magnetic field can only be regulated to a certain extent according to the original design method. The flexibility is poor and real-time regulation cannot be achieved. Summary of the invention

[0004] The object of the present invention is to provide a magnetic field regulating device which has small size, low energy consumption and can flexibly regulate the magnetic field, and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A magnetic field regulating device comprises: a composite magnetic element pair, wherein the composite magnetic elements in the composite magnetic element pair are arranged at intervals, the composite magnetic elements comprise a ferromagnetic layer and a piezoelectric layer, and the piezoelectric layer is electrically connected to an external voltage source.

[0007] Furthermore, the cross-section of the composite magnetic element is square.

[0008] Furthermore, the distance between the composite magnetic elements is less than half of the length of the composite magnetic element.

[0009] Furthermore, the ferromagnetic layer is formed of a ferromagnetic material with a magnetostriction coefficient of ≥50 ppm and a static magnetic permeability of ≥10000.

[0010] More specifically, the ferromagnetic material is FeCoB or FeGaB or FeCoBSi or FeCoB.

[0011] Furthermore, the piezoelectric layer is formed of a piezoelectric material with an electrostriction coefficient of ≥500ppm.

[0012] More specifically, the piezoelectric material is PZT or PZN-PT or PMN-PT or AlN or HfO2.

[0013] Furthermore, the composite magnetic element is symmetrically arranged on a substrate, and includes a lower electrode, a composite magnetic layer, an insulating layer and an upper electrode which are sequentially arranged on the substrate. The composite magnetic layer includes a piezoelectric layer and a ferromagnetic layer located on the piezoelectric layer. The lower electrode and the upper electrode are used to realize the electrical connection between the piezoelectric layer in the composite magnetic layer and an external voltage source.

[0014] More specifically, the thickness of the composite magnetic element is 500 nm to 5000 nm.

[0015] The present invention also provides a method for preparing the magnetic field regulating device, the steps of which are as follows:

[0016] providing a substrate;

[0017] depositing a first conductive layer on the substrate;

[0018] depositing a composite magnetic layer on the first conductive layer;

[0019] depositing an insulating layer on the composite magnetic layer;

[0020] A second conductive layer is deposited on the exposed surfaces of the insulating layer and the composite magnetic layer, and the first conductive layer and the second conductive layer are electrically connected to an external voltage source.

[0021] It can be seen from the above technical scheme that the composite magnetic element of the present invention is a composite structure of piezoelectric material and ferromagnetic material. The magnetic permeability of the magnetic material is changed by the electrostrictive effect of the piezoelectric material, and the local magnetic field is regulated by the guiding effect of the magnetic material on the external magnetic field. The magnetic field of the micro-region can be continuously and real-time regulated by changing the voltage. The composite magnetic element can be made by semiconductor technology, and has the advantages of extremely low power consumption, low price and small size. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention, 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 of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a schematic diagram of the influence of a magnetic material on the surrounding magnetic field when it is in a magnetic field;

[0024] Figure 2a It is a schematic diagram of the effect of two magnetic materials with similar magnetic permeability on the surrounding magnetic field when they are in the same magnetic field;

[0025] Figure 2b It is a schematic diagram of the effect of two magnetic materials with greatly different magnetic permeabilities on the surrounding magnetic field when they are in the same magnetic field;

[0026] Figure 3a and Figure 3b They are the hysteresis loop diagrams of the composite magnetic material before and after voltage is applied;

[0027] Figure 4 It is a structural schematic diagram of a magnetic field regulating device according to an embodiment of the present invention;

[0028] Figure 5a and Figure 5b They are schematic diagrams of the change in magnetic field direction in the area between two composite magnetic materials after applying different voltages;

[0029] Figures 6a to 6e Schematic diagram of the preparation process of an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the above and other purposes, features and advantages of the present invention more obvious, embodiments of the present invention are specifically cited below and described in detail with reference to the accompanying drawings.

[0031] like Figure 1 As shown, when a square (rectangular or square) magnetic material Q is placed in a magnetic field, since the magnetic permeability of the magnetic material Q is increased by at least 3 to 5 orders of magnitude relative to the magnetic permeability of the external space (air), the magnetic material Q will affect the magnetic field distribution around it, and the magnetic circuit will bend near the periphery of the magnetic material Q (the degree of bending of the magnetic circuit is related to the magnetic permeability of the magnetic material), especially at the four corners of the magnetic material Q, the direction of the magnetic field will change significantly, and may even flip 90°.

[0032] When two magnetic materials are placed symmetrically in the same magnetic field, when the magnetic permeabilities of the two magnetic materials are similar or differ greatly, the local magnetic field in the area between the two magnetic materials will also have different changes. Figure 2a The figure shows the distribution diagram of the magnetic field around the magnetic material when two rectangular magnetic materials Q1 and Q2 with similar (or equal) magnetic permeabilities are placed in the same magnetic field. Figure 2aAs shown, the magnetic field distribution between the two magnetic materials Q1 and Q2 will be affected by the two magnetic materials Q1 and Q2 at the same time. Since the magnetic permeability of the magnetic materials Q1 and Q2 is much greater than the magnetic permeability of the external space (air), most of the magnetic field will pass through the magnetic material. When the magnetic permeabilities of the two spaced magnetic materials Q1 and Q2 are similar or equal, the magnetic field competitiveness of the two magnetic materials Q1 and Q2 is the same, and almost no magnetic field passes through the area between the two magnetic materials Q1 and Q2. Therefore, the magnetic field intensity in this area is very small, or even approaches 0.

[0033] When the magnetic permeabilities of two magnetic materials Q1 and Q2 placed at intervals in the same magnetic field differ greatly, such as more than 10 times, the magnetic field passing through the magnetic material with smaller magnetic permeability will become less, while the magnetic field passing through the magnetic material with larger magnetic permeability will become more, that is, a part of the magnetic field at the magnetic material with smaller magnetic permeability will be shunted (attracted) by the magnetic material with larger magnetic permeability, and this part of the magnetic field will pass through the area between the two magnetic materials Q1 and Q2, so that the magnetic field strength in this area is not zero ( Figure 2b ).

[0034] The basic idea of ​​the present invention is to place two magnetic materials with different magnetic permeabilities symmetrically at intervals, and use the characteristic that the two magnetic materials with different magnetic permeabilities will affect the magnetic field in the area between the two to adjust the local magnetic field. In order to achieve the purpose of real-time regulation, the magnetic material of the present invention is a composite magnetic material composed of ferromagnetic material and piezoelectric material, and the magnetic permeability of the composite magnetic material is controlled by applying an external voltage by using the electrostrictive effect of the piezoelectric material and the inverse magnetostrictive effect of the ferromagnetic material, so as to achieve the purpose of adjusting the magnetic field distribution in the local area between the two magnetic materials.

[0035] The above is the core idea of ​​the present invention. The technical scheme of the embodiment of the present invention will be clearly and completely described below in combination with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] The composite magnetic material of the present invention is composed of a piezoelectric material and a ferromagnetic material. When a voltage is applied to the piezoelectric material, the piezoelectric material will deform under the action of the voltage based on the characteristics of the piezoelectric material. The deformation will be further transmitted to the ferromagnetic material, causing the magnetic permeability of the ferromagnetic material to change due to the deformation, thereby affecting the distribution of the external magnetic field. Figure 3aAs shown in the figure, when no voltage is applied to the piezoelectric material, the slope of the hysteresis loop of the composite magnetic material (ferromagnetic material) is very large, and the initial magnetic permeability is extremely high. When the piezoelectric material bonded to the ferromagnetic material is loaded with voltage, the magnetic permeability of the composite magnetic material will change due to deformation. Figure 3b As shown, after the piezoelectric material is used for regulation, the magnetic permeability of the composite magnetic material decreases, and a larger external magnetic field is required for the magnetic moment to reach saturation.

[0037] The ferromagnetic material of the present invention preferably adopts a ferromagnetic material with a magnetostriction coefficient of ≥50ppm and a static magnetic permeability of ≥10000, and the piezoelectric material preferably adopts a piezoelectric material with an electrostriction coefficient of ≥500ppm. The composite magnetic material can be made by a physical sputtering method, such as a magnetron sputtering method, by depositing it on a substrate in a vacuum chamber at one time. More specifically, the ferromagnetic material can adopt a ferromagnetic material such as FeCoB or FeGaB or FeCoBSi or FeCoB, and the piezoelectric material can adopt a piezoelectric material such as PZT or PZN-PT or PMN-PT or AlN or HfO2.

[0038] like Figure 4 As shown, the magnetic field regulating device of this embodiment includes two composite magnetic elements A1 and A2 arranged symmetrically at intervals. The composite magnetic elements A1 and A2 are deposited on a substrate 1, and the distance d between the composite magnetic elements A1 and A2 is less than half of the length L of the composite magnetic elements. The composite magnetic elements A1 and A2 have the same structure, and both include a ferromagnetic layer formed by a ferromagnetic material and a piezoelectric layer formed by a piezoelectric material. The piezoelectric layer is electrically connected to an external voltage source through electrodes (B, C), so that a voltage can be loaded on the piezoelectric layer to change the magnetic permeability of the composite magnetic element (ferromagnetic layer). The magnetic field regulating device of the present invention can be prepared by conventional semiconductor preparation processes such as photolithography and magnetron sputtering deposition.

[0039] The regions E1 and E2 located between the two composite magnetic elements A1 and A2 are controllable magnetic field adjustment regions. When there is an external magnetic field along the positive direction Y, a voltage is applied to the piezoelectric layers of the composite magnetic elements A1 and A2 through electrodes B and C to adjust the magnetic permeability of the composite magnetic elements A1 and A2 (ferromagnetic materials), thereby changing the magnetic field strength of the regions E1 and E2, that is, the magnetic field direction of the regions E1 and E2 is controlled by the magnetic permeability of the composite magnetic elements A1 and A2.

[0040] Reference Figure 5a and Figure 5b The magnetic field diagrams of the region between the composite magnetic elements A1 and A2 are shown respectively when different voltages are applied to the two composite magnetic elements A1 and A2 to change the magnetic permeability of the composite magnetic elements A1 and A2. When the magnetic permeability of the composite magnetic element A1 is much higher than that of the composite magnetic element A2, there is a magnetic field along the negative Y direction at E1, while there is a magnetic field along the positive Y direction at E2 ( Figure 5a This directional distribution will be reversed when the magnetic permeability of the composite magnetic element A2 is higher ( Figure 5b ).from Figure 5a and Figure 5b It can be seen that when the magnetic permeabilities of the composite magnetic elements A1 and A2 change, the magnetic field in the area between the two can achieve a 180° flip. For example, different voltages are first applied to make the magnetic permeabilities of the composite magnetic elements A1 and A2 1000 and 100 respectively, and then a reverse voltage is applied to change the magnetic permeabilities of the composite magnetic elements A1 and A2 to 100 and 1000 respectively. At this time, the direction of the magnetic field between the two composite magnetic elements A1 and A2 (E1, E2) will be flipped, thereby achieving the purpose of regulating the magnetic field.

[0041] Figures 6a to 6e The preparation process of the embodiment of the present invention is shown in the following figure. Figures 6a to 6e The preparation method of the magnetic field regulating device of the present invention is further described as follows:

[0042] Step 1: Figure 6a As shown, a substrate 21 is provided, and the substrate 21 is pre-treated. The substrate 21 has good insulation properties, and the substrate 21 can be a Si substrate;

[0043] The pretreatment step includes: ultrasonically cleaning the substrate 21 with acetone, alcohol and deionized water for 5 minutes, then drying it with N2, and baking it in an oven at 115°C for 20 minutes;

[0044] Step 2: Form a first predefined pattern on the substrate 21 using photolithography technology, and deposit a first conductive layer 22 (corresponding to the first predefined pattern) on the substrate 21 using a magnetron sputtering thin film growth process. Figure 6b ), the first conductive layer 22 can be deposited from conductive non-magnetic metal materials such as Cu, Au, etc., and the thickness can be 10nm to 50nm. The first conductive layer 22 is used to form the lower electrode ( Figure 4 C), after removing the photoresist with acetone, a lower electrode is formed on the substrate 21;

[0045] Step 3: Form a second predefined pattern on the first conductive layer 22 by photolithography, and deposit a composite magnetic layer 23 (comprised of a piezoelectric layer and a ferromagnetic layer) corresponding to the second predefined pattern on the first conductive layer 22 by using a ferromagnetic material and a piezoelectric material. Figure 6c ), forming a multilayer structure of substrate-lower electrode-piezoelectric layer-ferromagnetic layer; the thickness of the composite magnetic layer 23 is related to the size of the actual device and can be 500nm to 5000nm;

[0046] Step 4: remove the photoresist with acetone, form a third predefined pattern on the composite magnetic layer 23 by photolithography, and grow an insulating layer 24 ( Figure 6d ), the insulating layer 24 is used to isolate the lower electrode from the upper electrode, and its thickness may be about 50nm thicker than the composite magnetic layer 23, and the insulating layer 24 may be formed of insulating materials such as SiO2, Al2O3, etc.;

[0047] Step 5, remove the photoresist with acetone, form a fourth predefined pattern on the exposed surfaces of the insulating layer 24 and the composite magnetic layer 23, and grow a second conductive layer 25 corresponding to the fourth predefined pattern on the exposed surfaces of the insulating layer 24 and the composite magnetic layer 23, the second conductive layer 25 is used to form an upper electrode, and the material of the second conductive layer 25 is the same as that of the first conductive layer 22; the upper electrode and the lower electrode are used to realize the electrical connection between the piezoelectric layer and the external voltage source, and after cleaning with acetone and removing the photoresist, a magnetic field regulating device is obtained.

[0048] In the above steps, the method for forming the predefined pattern is as follows: after adding photoresist to the substrate, the substrate is first rotated at 600 rpm for 10 seconds on a coating machine so that the photoresist covers the Si wafer, and then rotated at 4000 rpm for 40 seconds to make the thickness of the photoresist uniform; the Si substrate with the spin-coated photoresist is placed in an oven and heated at 115°C for 20 minutes to completely cure the photoresist; the photoresist layer is exposed to ultraviolet light through a mask of a predefined pattern; and the excess photoresist is developed to remove the excess photoresist, leaving a predefined pattern on the Si substrate.

[0049] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A magnetic field regulating device, characterized in that: include: A composite magnetic element pair, wherein two composite magnetic elements of the composite magnetic element pair are symmetrically arranged on a substrate, the composite magnetic element comprises a ferromagnetic layer and a piezoelectric layer, and the piezoelectric layer is electrically connected to an external voltage source; The composite magnetic element comprises a lower electrode, a composite magnetic layer, an insulating layer and an upper electrode which are sequentially arranged on the substrate, the composite magnetic layer comprises a piezoelectric layer and a ferromagnetic layer located on the piezoelectric layer, and the lower electrode and the upper electrode are used to realize electrical connection between the piezoelectric layer in the composite magnetic layer and an external voltage source; The area between the two composite magnetic elements is a magnetic field controllable adjustment area; applying voltage to the piezoelectric layers of the two composite magnetic elements can adjust the magnetic permeability of the two composite magnetic elements and change the magnetic field strength of the magnetic field controllable adjustment area; the magnetic field direction of the magnetic field controllable adjustment area is controlled by the magnetic permeability of the two composite magnetic elements.

2. The magnetic field regulating device according to claim 1, characterized in that: The cross-section of the composite magnetic element is a square.

3. The magnetic field regulating device according to claim 1, characterized in that: The distance between the composite magnetic elements is less than half of the length of the composite magnetic elements.

4. The magnetic field regulating device according to claim 1, characterized in that: The ferromagnetic layer is formed of a ferromagnetic material with a magnetostriction coefficient of ≥50 ppm and a static magnetic permeability of ≥10000.

5. The magnetic field regulating device according to claim 4, characterized in that: The ferromagnetic material is FeCoB or FeGaB or FeCoBSi or FeCoB.

6. The magnetic field regulating device according to claim 1, characterized in that: The piezoelectric layer is formed of a piezoelectric material having an electrostriction coefficient of ≥500 ppm.

7. The magnetic field regulating device according to claim 6, characterized in that: The piezoelectric material is PZT or PZN-PT or PMN-PT or AlN or HfO2.

8. The magnetic field regulating device according to claim 1, characterized in that: The thickness of the composite magnetic element is 500nm-5000nm.

9. The method for preparing a magnetic field regulating device according to any one of claims 1 to 8, characterized in that: Here are the steps: providing a substrate; depositing a first conductive layer on the substrate; depositing a composite magnetic layer on the first conductive layer; depositing an insulating layer on the composite magnetic layer; A second conductive layer is deposited on the exposed surfaces of the insulating layer and the composite magnetic layer, and the first conductive layer and the second conductive layer are electrically connected to an external voltage source.

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