WO2021128720A1

WO2021128720A1 - Eddy current suppression structure and manufacturing method therefor

Info

Publication number: WO2021128720A1
Application number: PCT/CN2020/091786
Authority: WO
Inventors: 彭春瑞; 李君儒; 陈锶; 高杨; 任万春
Original assignee: 四川爆米微纳科技有限公司
Priority date: 2019-12-26
Filing date: 2020-05-22
Publication date: 2021-07-01

Abstract

An eddy current suppression structure, comprising a magnetostriction layer (1) and insulating dielectric layers (2, 3). The insulating dielectric layers (2, 3) are provided in the magnetostriction layer (1) and are used for breaking an eddy current so as to suppress eddy current loss of a bulk acoustic wave magnetoelectric antenna. The insulating dielectric layers (2, 3) are inserted into the magnetostriction layer (1) to reduce eddy current loss, so that the radiation efficiency of the bulk acoustic wave magnetoelectric antenna is improved, and the problems in the prior art of discontinuous stress and low radiation efficiency of a magnetoelectric antenna caused by a magnetostriction layer (1) having air gaps are solved. The insulating dielectric layers (2, 3) are used as spacer layers, so the soft magnetic characteristic of the magnetostriction layer (1) can be improved, the coercive force of the magnetostriction layer (1) is effectively reduced, and the sensitivity of a radiation region is improved. By means of simulation analysis, the solution can effectively reduce the eddy current loss by more than 65%, and greatly improve the radiation efficiency of a magnetoelectric antenna.

Description

Eddy current suppression structure and preparation method thereof

Technical field

The invention relates to the field of radio frequency microelectronic mechanical systems, in particular to an eddy current suppression structure and a preparation method thereof.

Background technique

At present, the commonly used antennas in smart phones, tablet computers, radio frequency devices and radars are electrically small antennas based on the working principle of current conduction. They are usually large in size and difficult to achieve miniaturization. They also have disadvantages such as difficulty in impedance matching and low radiation efficiency. . The bulk acoustic wave magnetoelectric antenna uses the principle of bulk acoustic wave resonance and the magnetoelectric effect to radiate electromagnetic signals, which fundamentally solves the problems of impedance matching of electric small antennas and low radiation efficiency. Moreover, using the principle of acoustic wave resonance can realize the miniaturization of the device. . The bulk acoustic wave magnetoelectric antenna is composed of a piezoelectric layer and a magnetostrictive layer cross composite.

In the bulk acoustic wave magnetoelectric antenna, the magnetostrictive layer is used as the radiation layer of the transmitting antenna. In this layer, electromagnetic signals are generated through the electromagnetic effect to radiate electromagnetic waves to the outside. The energy utilization rate directly determines the radiation efficiency of the transmitting antenna. Magnetostrictive layer often chooses FeGaB magnetic film with higher conductivity. Under the excitation of internal magnetic field, large eddy current loss will be generated, which will affect the radiation power of transmitting antenna. On the premise of ensuring the good soft magnetic properties of the magnetostrictive layer, reducing the eddy current loss will greatly improve the radiation efficiency of the magnetoelectric antenna. When a bulk acoustic wave magnetoelectric antenna is used in a radio frequency system, the eddy current loss will cause excessive energy loss, resulting in a reduction in the antenna's radiation efficiency and limiting its application range.

Zhi Yao and Yuanxun Ethan Wang in the title "3D ADI-FDTD Modeling of Platform Reduction with Thin Film Ferromagnetic Material" proposed a 3D ADI-FDTD-based eddy current suppression method, which uses the magnetostrictive layer to be divided into long strips. The eddy current ring is broken in a way to achieve the purpose of suppressing eddy current loss. The key technologies of this method are:

(1) The width of the divided strip should be equal to the thickness, so that the interrupted eddy current loop can be small enough.

(2) The longitudinal direction of the strip should be along the direction of magnetic flux. There is an air gap between adjacent strips. Because of the high conductivity of the magnetostrictive layer, most of the electromagnetic field is concentrated in the air gap. Its structure is shown in Figures 1 and 2.

Although the eddy current loss suppression method proposed by the above scheme can suppress the eddy current loss very well, it will also greatly reduce the radiation efficiency of the magnetoelectric antenna. The main problems are: (1) Air gap is used as the left and right gap between the divided strips. (Along the y-axis direction) and the gap between the upper and lower layers (along the z-axis direction), the stress cannot be continuously transferred between the left and right and the upper and lower layers when the bulk acoustic wave magnetoelectric antenna is actually working. Only the lower magnetostrictive film works. There is no stress conduction in the upper magnetostrictive layer, and electromagnetic waves cannot be excited, thereby greatly reducing the radiation efficiency of the entire magnetostrictive layer. (2) In this scheme, the width of each air gap along the y-axis direction is 0.2μm, which accounts for 1/5 of the width of a single magnetic film strip, and the thickness of each air gap along the z-axis direction is 0.3μm which accounts for 1/5 of the width of a single magnetic film strip. /2. Although a larger air gap can well suppress the eddy current loss, it will reduce the soft magnetic properties of the entire magnetostrictive layer, resulting in too low radiation efficiency of the magnetoelectric antenna.

Summary of the invention

The technical problem to be solved by the present invention is to provide an eddy current suppression structure and a preparation method thereof.

The technical solution of the present invention to solve the above technical problems is as follows: an eddy current suppression structure including a magnetostrictive layer and an insulating medium layer disposed in the magnetostrictive layer for breaking the eddy current.

The beneficial effects of the present invention are: the present invention inserts an insulating dielectric layer in the magnetostrictive layer to reduce eddy current loss, improve the radiation efficiency of the bulk acoustic wave magnetoelectric antenna, and solve the problem of the air gap spaced magnetostrictive layer in the prior art. This leads to the problems of discontinuous stress and low radiation efficiency of the magnetoelectric antenna. Using an insulating medium layer as a spacer layer can improve the soft magnetic properties of the magnetostrictive layer, effectively reduce the coercivity of the magnetostrictive layer, and improve the sensitivity of the radiation area. Through simulation analysis, this solution can effectively reduce the eddy current loss by more than 65%, and greatly improve the radiation efficiency of the magnetoelectric antenna.

On the basis of the above technical solution, the present invention can also be improved as follows:

Further, a first insulating medium layer is arranged in the magnetostrictive layer along its thickness direction and/or a second insulating medium layer is arranged in the magnetostrictive layer along its width direction.

The beneficial effect of adopting the above-mentioned further solution is that the present invention divides the eddy current into volume eddy current and surface eddy current according to the skin effect of the induced current in the magnetostrictive layer, and the first insulating dielectric layer can well suppress the volume eddy current, thereby reducing the eddy current loss. ; The second insulating dielectric layer can well suppress the surface eddy current, thereby reducing the eddy current loss.

Further, at least one layer of the first insulating medium layer is arranged in the magnetostrictive layer along its thickness direction.

The beneficial effect of adopting the above-mentioned further solution is that the first insulating dielectric layer can well suppress the body eddy current, thereby reducing the eddy current loss.

Further, the first insulating dielectric layer is three layers parallel to each other, each of the first insulating dielectric layer has a thickness of 5-100 nm, the magnetostrictive layer is made of FeGaB film, and the total thickness of the FeGaB film is 1μm, the conductivity of the first insulating dielectric layer ranges from 0-100S/m, and the first insulating dielectric layer is made of any one or more of _{Al 2} O ₃ , Si ₃ N _{4 and AlN} .

The beneficial effect of adopting the above further scheme is that the simulation results show that 3 layers are sufficient to solve the problem of bulk eddy current suppression; the first insulating dielectric layer is 5-100nm, and the bulk eddy current can be well suppressed; FeGaB film is a high-quality magnetostrictive Layer material; when the insulating dielectric layer is the above material, it has a good eddy current suppression effect.

Further, at least one second insulating dielectric layer is arranged in the magnetostrictive layer along its width direction.

The beneficial effect of adopting the above-mentioned further solution is that the second insulating dielectric layer can well suppress the surface eddy current, thereby reducing the eddy current loss.

Further, the second insulating dielectric layer is three layers parallel to each other, each of the second insulating dielectric layer has a thickness of 5-30 nm, the magnetostrictive layer is made of FeGaB film, and the total thickness of the FeGaB film is 1μm, the conductivity of the second insulating dielectric layer ranges from 0-100S/m, and the second insulating dielectric layer is made of any one or more of _{Al 2} O ₃ , Si ₃ N _{4 and AlN} .

The beneficial effect of adopting the above-mentioned further scheme is that the simulation results show that three layers are sufficient to solve the problem of surface eddy current suppression; the second insulating dielectric layer is 5-30nm, and the surface eddy current can be well suppressed; FeGaB film is a high-quality magnetostrictive Layer material; when the insulating dielectric layer is the above material, it has a good eddy current suppression effect.

Further, at least one first insulating medium layer is arranged in the magnetostrictive layer along its thickness direction, at least one second insulating medium layer is arranged in the magnetostrictive layer along its width direction, and the first insulating medium The layer and the second insulating dielectric layer are intersected and arranged at intervals.

The beneficial effect of adopting the above-mentioned further scheme is to insert insulating dielectric layers alternately spaced along the thickness and width in the magnetostrictive layer to reduce its body eddy current and surface eddy current losses, and a comprehensive consideration of body eddy current and surface eddy current insertion insulation is proposed. The isolation structure of the dielectric layer minimizes the eddy current loss of the magnetostrictive layer. It solves the problem that the air gap spaced magnetostrictive layer in the prior art solution causes the stress discontinuity and the low radiation efficiency of the magnetoelectric antenna. Using an insulating medium layer as a spacer layer can improve the soft magnetic properties of the magnetostrictive layer, effectively reduce the coercivity of the magnetostrictive layer, and improve the sensitivity of the radiation area. Through simulation analysis, this solution can effectively reduce the eddy current loss by more than 65%, and greatly improve the radiation efficiency of the magnetoelectric antenna.

Further, the first insulating medium layer is three layers and parallel to each other, the second insulating medium layer is three layers and parallel to each other, each layer of the first insulating medium layer has a thickness of 5-100 nm, and each layer of the first insulating medium layer The thickness of the second insulating medium layer is 5-30 nm, the material of the magnetostrictive layer is FeGaB film, the total thickness of the FeGaB film is 1 μm, and the conductivity ranges of the first insulating medium layer and the second insulating medium layer It is 0-100 S/m, and both the first insulating dielectric layer and the second insulating dielectric layer are made of any one or more of _{Al 2} O ₃ , Si ₃ N _{4 and AlN.}

The beneficial effect of adopting the above-mentioned further scheme is that through simulation results, 3 layers are sufficient to solve the problem of surface eddy current suppression. The thickness of the first insulating dielectric layer is 5-100nm, and the second insulating dielectric layer is 5-30nm. The surface eddy current can be well obtained. The above limitation suppresses the eddy current loss in the magnetic film under the premise of ensuring that the size of the insulating medium layer is as small as possible, and proposes a magnetic film structure that inserts the smallest size insulating medium to suppress the eddy current. While effectively suppressing the eddy current loss in the magnetostrictive layer, it can effectively ensure the good soft magnetic properties of the magnetostrictive layer, improve the radiation efficiency of the magnetoelectric antenna, and make the bulk acoustic wave magnetoelectric antenna more suitable for wireless communication applications; FeGaB The thin film is a high-quality magnetostrictive layer material; when the insulating medium layer is the above material, it has a good eddy current suppression effect.

The present invention also relates to a magnetoelectric antenna, including an upper electrode, and further including the eddy current suppression structure, the eddy current suppression structure being arranged on the upper electrode.

The present invention also relates to a method for preparing the eddy current suppression structure, including: Step 1: Depositing a magnetostrictive layer on the body (the upper electrode of the bulk acoustic wave resonator) by magnetron sputtering; Step 2: In the step 1. Use a magnetron sputtering method to deposit a first insulating medium layer along its thickness on the magnetostrictive layer formed; Step 3: deposit a magnetostrictive layer again on the first insulating medium layer formed in step 2. Stretching layer; Step 4: Obtain the eddy current suppression structure directly, or repeat the above steps 2-3 at least once to obtain the eddy current suppression structure; or, Step a: Use on the body (the upper electrode of the bulk acoustic wave resonator) Magnetron sputtering method is used to deposit the magnetostrictive layer; Step b: Use a spinner to evenly cover a layer of photoresist on the magnetostrictive layer, and then perform pre-baking, exposure and development in sequence; Step c: Use a dry method Etching etches at least one groove in the thickness direction of the magnetostrictive layer on the structure formed in step b; step d: sputtering on the structure formed in step c by a magnetron sputtering method At least one second insulating dielectric layer is formed in the thickness direction of the magnetostrictive layer; step e: removing the photoresist on the surface of the magnetostrictive layer by a metal stripping process; step f: using chemical machinery Grinding to smooth the second insulating medium layer higher than the surface of the magnetostrictive layer; or, step A: depositing the magnetostrictive layer on the body (the upper electrode of the bulk acoustic wave resonator) by magnetron sputtering; Step B: Depositing a first insulating medium layer in the thickness direction of the magnetostrictive layer formed in Step A on the magnetostrictive layer formed in Step A by using a magnetron sputtering method; Step C: Depositing a magnetostrictive layer on the first insulating dielectric layer formed in step B; Step D: directly obtaining the first insulating dielectric layer structure, or repeating the above step BC at least once to obtain the first insulating dielectric layer structure Step E: Use a spinner to uniformly cover a layer of photoresist on the first insulating dielectric layer structure, and then perform pre-baking, exposure and development in sequence; Step F: Use dry etching to form in Step E At least one groove in the width direction of the magnetostrictive layer is etched on the structure; Step G: Sputter the structure formed in the step F using a magnetron sputtering method to form the magnetostrictive layer At least one layer of the second insulating dielectric layer in the width direction; Step H: Use a metal lift-off process to remove the photoresist on the surface of the first insulating dielectric layer structure formed in Step D; Step I: Use chemical machinery Grinding smoothes the second insulating dielectric layer higher than the surface of the first insulating dielectric layer structure formed in the step D.

The beneficial effect of adopting the above-mentioned further solution is that the above-mentioned method can be used to realize the production of eddy current suppression structure simply, quickly and under the premise of ensuring the eddy current suppression function, thereby improving the radiation efficiency of the magnetoelectric antenna.

Description of the drawings

Fig. 1 is a figure 1 of a prior art eddy current loss suppression structure;

Figure 2 is the second diagram of the prior art eddy current loss suppression structure;

3 is a schematic diagram of the eddy current suppression structure of the magnetostrictive layer body of the present invention;

Fig. 4 is a structural diagram of the magnetostrictive layer eddy current suppression structure of the present invention;

Fig. 5 is a 3×3 eddy current suppression structure of the magnetostrictive layer of the present invention;

Figure 6 is a process flow diagram of the eddy current suppression structure of the present invention;

7 is a schematic diagram of the influence of the thickness of the _{Al 2} O ₃ film of the present invention on the surface loss;

8 is a schematic diagram of the influence of the number of _{Al 2} O ₃ film layers on the surface loss of the present invention;

9 is a schematic diagram of the influence of the thickness of the _{Al 2} O ₃ film of the present invention on the body loss;

10 is a schematic diagram of the influence of the number of _{Al 2} O ₃ film layers of the present invention on the body loss;

Fig. 11 is a schematic diagram of the total loss density corresponding to _{different Al 2} O _{3 thicknesses of the present invention.}

In the drawings, the list of parts represented by each number is as follows:

1. Magnetostrictive layer, 2. First insulating medium layer, 3. Second insulating medium layer, 4. Upper pole of bulk acoustic wave resonator, 5. Photoresist, 6. Mask, 7. Air gap.

Detailed ways

The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples cited are only used to explain the present invention, and not used to limit the scope of the present invention.

Use Comsol simulation software to simulate the surface eddy current and volume eddy current of the magnetostrictive layer, and the verification results are shown in the figure.

As shown in Figure 7, _{the surface loss density of the Al 2} O ₃ thickness (insulating dielectric layer) within 5 nm is significantly reduced, and although there is a gradual decrease thereafter, the reduction rate is basically maintained within 5%, so that the surface eddy current is obtained Very good suppression. Therefore, the _{eddy current loss on the inner surface of the Al 2} O ₃ thickness of 5 nm is well suppressed, and the Al ₂ O ₃ thickness can be appropriately thickened according to the process conditions. While keeping the _{total thickness of the inserted Al 2} O ₃ insulating layer unchanged, divide it into 2, 3, 4, and 5 layers, evenly spaced in the FeGaB metal layer. The total thickness is 100nm in Figure 8 (according to the process When the condition is appropriately thickened), the _{change trend of the surface eddy current density corresponding to the number of Al 2} O ₃ insulating layers, with the increase of the number of layers, the surface loss density is significantly reduced, but the rate of decrease after 3 layers is less than 20%, and the rate of decrease Gradually flatten out. Therefore, 3 layers are sufficient to solve the problem of surface vortex suppression.

According to the simulation results, the changing trend of the body loss density corresponding to _{different Al 2} O _{3 thicknesses is shown in Fig. 9.} _{After Al 2} O _{3 with a} thickness of 5 nm is added, the internal loss density is reduced by more than 60%. When the _{thickness of Al 2} O ₃ is about 30 nm, the eddy current loss density is the smallest, and then there is a slight growth trend, with a growth rate of less than 1%. Therefore, the _{eddy current of the Al 2} O ₃ insulating layer with a thickness of 5-30 nm can be well suppressed. The _{total thickness of the Al 2} O ₃ layer was set to 30 nm at the minimum volume eddy current loss density, and it was divided into 2, 3, 4, and 5 layers. The results are shown in FIG. 10. With _{the increase of the number of Al 2} O ₃ insulating layers, the bulk eddy current loss density decreases significantly. Like the surface loss density, the rate of decrease gradually slows down after 3 layers.

Considering the optimal separation methods of surface eddy currents and volume eddy currents, the 3×3 cross separation method as shown in Figure 6 is used to calculate the surface eddy currents and volume eddy currents respectively. The simulation results of the total loss density are shown in Figure 11. _{Obviously, the total loss density of the cross-space is the lowest. When the thickness of Al 2} O ₃ added in the thickness direction (z-axis direction) and the width direction (y-axis direction) are both 10nm, the thickness direction (z-axis direction) ) into three-layer Al ₂ O ₃ insulating layer and the insert 3 layer Al ₂ O ₃ insulating layer in the width direction (y axis direction), the total loss density decreased by about 10% and 47%, while the use of cross-compartments of 3 × 3 The reduction rate is 65%, and the vortex suppression efficiency is the highest. Therefore, the use of 3×3 cross-spaced method is the best method for eddy current suppression.

Example 1

As shown in Figure 3-11, as the basic solution of the present invention, an eddy current suppression structure includes a magnetostrictive layer 1, and also includes an insulating medium layer, the insulating medium layer is disposed in the magnetostrictive layer 1 for The eddy current is interrupted to suppress the eddy current loss of the bulk acoustic wave magnetoelectric antenna.

As shown in Fig. 3, as a further solution of this embodiment, at least one first insulating dielectric layer 2 is provided in the magnetostrictive layer 1 along its thickness direction.

As a further solution of this embodiment, the first insulating dielectric layer 2 is three layers and parallel to each other, the thickness of each first insulating dielectric layer 2 is 5-100 nm, and the material of the magnetostrictive layer 1 is FeGaB film, the total thickness of the FeGaB film is 1 μm, the conductivity range of the first insulating dielectric layer 2 is 0-100 S/m, and the first insulating dielectric layer 2 is composed of Al ₂ O ₃ , Si ₃ N ₄ and Made of any one or more materials in AlN.

Specifically, as shown in FIG. 3, the arrow indicates the direction of the magnetic flux, and the first insulating dielectric layer is arranged in parallel with the XOY surface (thickness direction), so as to realize its function of breaking the eddy current.

As shown in Figures 3 and 6, the method for preparing the eddy current suppression structure, Step 1: Use magnetron sputtering to deposit the magnetostrictive layer 1 on the upper electrode of the body's bulk acoustic wave resonator; Step 2: Formed in the step 1 The magnetron sputtering method is used to deposit the first insulating medium layer 2 along its thickness on the magnetostrictive layer 1; step 3: the magnetostrictive layer 2 is again deposited on the first insulating medium layer 2 formed in the step 2. Stretching layer 1; Step 4: Repeat the above steps twice to obtain the eddy current suppression structure.

Example 2

As shown in Fig. 4, as a further solution of this embodiment, at least one second insulating dielectric layer 3 is provided in the magnetostrictive layer 1 along its width direction.

As a further solution of this embodiment, the second insulating dielectric layer 3 is three layers parallel to each other, the thickness of each second insulating dielectric layer 3 is 5-30 nm, and the material of the magnetostrictive layer 1 is FeGaB film, the total thickness of the FeGaB film is 1 μm, the conductivity of the second insulating dielectric layer 3 is in the range of 0-100 S/m, and the second insulating dielectric layer 3 is composed of Al ₂ O ₃ , Si ₃ N ₄ and Made of any one or more materials in AlN.

Specifically, as shown in Figure 4, the arrow indicates the direction of the magnetic flux, and the second insulating dielectric layer is arranged parallel to the XOZ surface (width direction), so as to achieve its function of breaking the eddy current; and the insulating layer is parallel to the ZOY surface (length direction) The setting can not interrupt the eddy current.

4 and 6, the preparation method of the eddy current suppression structure, step a: use magnetron sputtering method to deposit the magnetostrictive layer 1 on the upper electrode of the body bulk acoustic wave resonator; step b: The magnetostrictive layer 1 is uniformly covered with a layer of photoresist 5, and then pre-baking, exposure and development are carried out in sequence; Step c: dry etching is used to etch the structure formed in the step b on the magnetostrictive layer 1 3 grooves in the thickness direction of the stretchable layer 1; step d: sputter on the structure formed in the step c by a magnetron sputtering method to form 3 layers of second insulating medium in the thickness direction of the magnetostrictive layer 1 Layer 3; Step e: Use a metal lift-off process to remove the photoresist 5 on the surface of the magnetostrictive layer 1; Step f: Use chemical mechanical polishing to remove the photoresist 5 above the surface of the magnetostrictive layer 1 The second insulating dielectric layer 3 is ground flat. In this method, the mask 6 is placed on the photoresist before etching to ensure that the non-groove part is not etched.

Example 3

As shown in Figures 5 and 6, as a further solution of this embodiment, at least one first insulating dielectric layer 2 is provided in the magnetostrictive layer 1 along its thickness direction, and the magnetostrictive layer 1 is provided along its width direction. There is at least one second insulating dielectric layer 3, and the first insulating dielectric layer 2 and the second insulating dielectric layer 3 are arranged at intervals and crossing each other.

As shown in Figures 5 and 6, as a further solution of this embodiment, the first insulating dielectric layer 2 is three layers and parallel to each other, and the second insulating dielectric layer 3 is three layers and parallel to each other. The thickness of the insulating medium layer 2 is 5-100 nm, the thickness of each second insulating medium layer 3 is 5-30 nm, the material of the magnetostrictive layer 1 is FeGaB film, and the total thickness of the FeGaB film is 1 μm. The conductivity range of the first insulating dielectric layer 2 and the second insulating dielectric layer 3 is 0-100S/m, and the first insulating dielectric layer 2 and the second insulating dielectric layer 3 are made of Al ₂ O ₃ , It is made of any one or more materials among _{Si 3} N _{4 and AlN.}

Specifically, as shown in Figure 5, the arrow indicates the direction of the magnetic flux, the first insulating dielectric layer is arranged parallel to the XOY surface (thickness direction), so as to achieve its function of breaking the eddy current; the second insulating layer and the ZOX surface (width direction) It is arranged in parallel to realize the function of breaking the eddy current, and the insulating layer is parallel to the ZOY surface (length direction), and the eddy current cannot be interrupted.

As shown in Figures 5 and 6, the method for preparing the eddy current suppression structure includes step A: depositing a magnetostrictive layer 1 on the upper electrode of the bulk acoustic wave resonator by magnetron sputtering; step B: forming in step A The first insulating medium layer 2 in the thickness direction of the magnetostrictive layer 1 formed in the step A is deposited on the magnetostrictive layer 1 by a magnetron sputtering method; step C: the first insulating medium layer 2 formed in the step B The magnetostrictive layer 1 is deposited on the first insulating medium layer 2; Step D: Repeat the above step BC twice to obtain the first insulating medium layer structure; Step E: Use a glue spinner to apply the first insulating medium layer The layer structure is uniformly covered with a layer of photoresist 5, and then pre-baking, exposure and development are carried out in sequence; Step F: Dry etching is used to etch the magnetostrictive layer 1 on the structure formed in Step E At least one groove in the width direction; step G: sputtering on the structure formed in step F by a magnetron sputtering method to form at least one layer of the second insulating medium in the width direction of the magnetostrictive layer 1 Layer 4; Step H: Use a metal lift-off process to remove the photoresist 5 on the surface of the first insulating dielectric layer structure formed in Step D; Step I: Use chemical mechanical polishing to be higher than that formed in Step D The second insulating dielectric layer 3 on the surface of the first insulating dielectric layer structure is ground flat. In this method, the mask 6 is placed on the photoresist before etching to ensure that the non-groove part is not etched.

The methods used in Examples 1-3 are all existing technologies in the field.

Bulk acoustic wave magnetoelectric antenna eddy current loss suppression method: the volume eddy current suppression method in the magnetostrictive layer adopts the thickness direction (z-axis direction) to insert the insulating medium layer, as shown in Figure 3; the middle surface eddy current suppression method of the magnetostrictive layer adopts Insert the insulating medium layer in the width direction (y-axis direction), as shown in Figure 4; the overall eddy current suppression method in the magnetostrictive layer adopts the insulating medium in the thickness direction (z-axis direction) and the width direction (y-axis direction) at the same time. Layer, as shown in Figure 5.

The magnetic material in the magnetostrictive layer is a FeGaB film with a thickness of 1 μm and a surface area of 100 μm×100 μm.

The conductivity range of the insulating dielectric layer is 0-100 S/m, such as Al ₂ O ₃ , Si ₃ N ₄ , and AlN.

The number of layers inserted into the insulating dielectric layer in the thickness direction and the width direction is 3×3, respectively.

The volume eddy current suppression method inserts the insulating dielectric layer along the thickness direction with a thickness of 5-30 nm, and the number of separation layers is 3 layers.

The surface eddy current suppression method inserts the insulating medium layer along the width direction with a width of 5-100 nm, and the number of separation layers is 3 layers. As shown in Figure 6.

The insertion of the insulating dielectric layer in the width direction is to etch the middle groove through a photolithography process, and then use the physical vapor deposition method to fill the insulating dielectric layer. The photolithography process uses reactive ion etching.

The following describes the embodiments of the present invention in detail with reference to FIG. 6:

Figure 6 is a process flow diagram of the eddy current suppression structure.

Step 1: Magnetron sputtering is used to deposit a FeGaB magnetic film on the upper electrode of the bulk acoustic wave resonator, and the thickness of the FeGaB magnetic film is 500 nm.

_{Step 2: Depositing an Al 2} O ₃ insulating layer on the FeGaB magnetic film by magnetron sputtering _{, the thickness of the Al 2} O ₃ insulating layer being 5-30 nm.

Step 3: _{Deposit a FeGaB magnetic film on the Al 2} O ₃ insulating layer, the thickness of the magnetic film is 500 nm.

Step 4: Use a glue spinner to evenly cover a layer of photoresist on the FeGaB magnetic film, pre-baking, exposing, and developing. The photoresist is a positive photoresist.

Step 5: Use dry etching to etch grooves in the magnetostrictive layer.

_{Step 6: Sputter the Al 2} O ₃ insulating layer in the magnetostrictive layer by magnetron sputtering.

Step 7: Use a metal lift-off process to remove the photoresist on the surface of the FeGaB magnetic film.

Step 8: Use chemical mechanical polishing to smooth the Al ₂ O ₃ insulating layer 3 above the surface of the FeGaB magnetic film.

In order to solve the above technical defects, the present invention proposes a method and structure for suppressing the eddy current loss of a bulk acoustic wave magnetoelectric antenna. This method suppresses the eddy current loss by inserting the insulating medium alternately spaced in the transverse and longitudinal directions in the magnetostrictive layer, and suppresses the eddy current loss in the magnetic film under the premise of ensuring that the size of the insulating medium layer is as small as possible. Insert the smallest size insulating medium to suppress eddy current magnetic film structure. This structure can effectively suppress the eddy current loss in the magnetostrictive layer, and can effectively ensure the good soft magnetic properties of the magnetostrictive layer, improve the radiation efficiency of the magnetoelectric antenna, and make the bulk acoustic wave magnetoelectric antenna more suitable for wireless communication. Application occasions. According to the skin effect of the induced current in the magnetostrictive layer, the present invention divides the eddy currents into volume eddy currents and surface eddy currents, and proposes a method for isolating the two by inserting an insulating dielectric layer, and constructs a minimum-size insulating medium for inserting The magnetic film structure that suppresses eddy current ensures that the eddy current loss reaches the minimum.

_{The present invention inserts Al 2} O ₃ insulating layers alternately spaced in the thickness and width directions in the magnetostrictive layer to reduce the body eddy current and surface eddy current loss, and minimize the eddy current loss of the magnetostrictive layer. It solves the problem that the air gap spaced magnetostrictive layer in the prior art solution causes the stress discontinuity and the low radiation efficiency of the magnetoelectric antenna. Using the Al ₂ O ₃ insulating layer as the spacer layer can improve the soft magnetic properties of FeGaB, effectively reduce the coercive force of FeGaB, and improve the sensitivity of the radiation area. Through simulation analysis, this solution can effectively reduce the eddy current loss by more than 65%, and greatly improve the radiation efficiency of the magnetoelectric antenna.

The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection of the present invention. Within range.

Claims

An eddy current suppression structure includes a magnetostrictive layer (1), and is characterized in that it also includes an insulating medium layer disposed in the magnetostrictive layer (1) for breaking the eddy current.
The eddy current suppression structure according to claim 1, wherein the magnetostrictive layer (1) is provided with a first insulating medium layer (2) and/or the magnetostrictive layer (1) along its thickness direction. A second insulating dielectric layer (3) is arranged in the width direction thereof.
The eddy current suppression structure according to claim 2, wherein at least one layer of the first insulating dielectric layer (2) is arranged in the magnetostrictive layer (1) along its thickness direction.
The eddy current suppression structure according to claim 3, characterized in that, the first insulating dielectric layer (2) is three layers parallel to each other, and the thickness of each first insulating dielectric layer (2) is 5- 100nm, the material of the magnetostrictive layer (1) is FeGaB film, the total thickness of the FeGaB film is 1μm, the conductivity range of the first insulating dielectric layer (2) is 0-100S/m, the first An insulating dielectric layer (2) is made of any one or more of Al 2 O 3 , Si 3 N 4 and AlN.
The eddy current suppression structure according to claim 2, wherein at least one second insulating dielectric layer (3) is arranged in the magnetostrictive layer (1) along its width direction.
The eddy current suppression structure according to claim 5, characterized in that the second insulating dielectric layer (3) is three layers parallel to each other, and the thickness of each second insulating dielectric layer (3) is 5- 30nm, the material of the magnetostrictive layer (1) is FeGaB film, the total thickness of the FeGaB film is 1μm, the conductivity of the second insulating dielectric layer (3) ranges from 0-100S/m, and the first The second insulating dielectric layer (3) is made of any one or more of Al 2 O 3 , Si 3 N 4 and AlN.
The eddy current suppression structure according to claim 2, wherein at least one first insulating medium layer (2) is arranged in the magnetostrictive layer (1) along its thickness direction, and the magnetostrictive layer (1) 1) At least one second insulating medium layer (3) is arranged in the inner portion along its width direction, and the first insulating medium layer (2) and the second insulating medium layer (3) are arranged at intervals and crossing each other.
The eddy current suppression structure according to claim 7, wherein the first insulating dielectric layer (2) is three layers and parallel to each other, and the second insulating dielectric layer (3) is three layers and parallel to each other, The thickness of each layer of the first insulating medium layer (2) is 5-100 nm, the thickness of each layer of the second insulating medium layer (3) is 5-30 nm, and the material of the magnetostrictive layer (1) is FeGaB thin film , The total thickness of the FeGaB film is 1 μm, the conductivity range of the first insulating dielectric layer (2) and the second insulating dielectric layer (3) is 0-100S/m, and the first insulating dielectric layer ( 2) and the second insulating dielectric layer (3) are made of any one or more of Al 2 O 3 , Si 3 N 4 and AlN.
A magnetoelectric antenna, comprising an upper electrode, characterized in that it further comprises the eddy current suppression structure according to any one of claims 1-7, and the eddy current suppression structure is arranged on the upper electrode.
A method for preparing the eddy current suppression structure according to any one of claims 2-9, characterized in that it comprises the following steps:

Step 1: Use magnetron sputtering to deposit a magnetostrictive layer (1) on the body;

Step 2: Depositing a first insulating dielectric layer (2) along the thickness direction of the magnetron sputtering method on the magnetostrictive layer (1) formed in the step 1;

Step 3: Depositing a magnetostrictive layer (1) again on the first insulating dielectric layer (2) formed in the step 2;

Step 4: Obtain the vortex suppression structure directly, or repeat the above steps 2-3 at least once to obtain the vortex suppression structure;

or,

Step a: Depositing a magnetostrictive layer (1) on the body by magnetron sputtering;

Step b: Use a glue spinner to evenly cover a layer of photoresist (5) on the magnetostrictive layer (1), and then perform pre-baking, exposure and development in sequence;

Step c: Use dry etching to etch at least one groove in the thickness direction of the magnetostrictive layer (1) on the structure formed in step b;

Step d: Sputtering on the structure formed in step c by a magnetron sputtering method to form at least one second insulating medium layer (3) in the thickness direction of the magnetostrictive layer (1);

Step e: removing the photoresist (5) on the surface of the magnetostrictive layer (1) by using a metal stripping process;

Step f: Use chemical mechanical polishing to smooth the second insulating dielectric layer (3) higher than the surface of the magnetostrictive layer (1);

or,

Step A: Depositing a magnetostrictive layer on the body by magnetron sputtering (1);

Step B: Depositing the first insulating medium layer in the thickness direction of the magnetostrictive layer (1) formed in the step A by using a magnetron sputtering method on the magnetostrictive layer (1) formed in the step A (2);

Step C: Depositing a magnetostrictive layer (1) on the first insulating dielectric layer (2) formed in the step B;

Step D: Obtain the first insulating dielectric layer structure directly, or repeat the above steps B-C at least once to obtain the first insulating dielectric layer structure;

Step E: Use a glue spinner to uniformly cover a layer of photoresist (5) on the first insulating dielectric layer structure, and then perform pre-baking, exposure and development in sequence;

Step F: Use dry etching to etch at least one groove in the width direction of the magnetostrictive layer (1) on the structure formed in Step E;

Step G: Sputter the structure formed in step F by using a magnetron sputtering method to form at least one second insulating medium layer (4) in the width direction of the magnetostrictive layer (1);

Step H: Use a metal lift-off process to remove the photoresist (5) on the surface of the first insulating dielectric layer structure formed in Step D;

Step I: Use chemical mechanical polishing to smooth the second insulating dielectric layer (3) that is higher than the surface of the first insulating dielectric layer structure formed in Step D.