Transverse excitation bulk acoustic wave resonator and filter

Abstract

The utility model discloses a transverse excitation bulk acoustic wave resonator and a filter, and relates to the technical field of resonators. The transverse excitation bulk acoustic wave resonator comprises a substrate, an insulating layer arranged on the substrate, a piezoelectric layer arranged on the insulating layer and an interdigital electrode arranged on the piezoelectric layer, the interdigital electrode comprises two electrode structures which are oppositely arranged, each electrode structure comprises a busbar and a plurality of electrode strips which are connected to the same side of the busbar in parallel in the first direction, and a gap area is formed between the electrode strip of one electrode structure and the busbar of the other electrode structure; the transverse excitation bulk acoustic wave resonator further comprises a phononic crystal structure located on the substrate and arranged in the gap area, the phononic crystal structure comprises a plurality of phononic crystal parts arranged in a matrix mode, the phononic crystal parts are arranged in M columns in the first direction and arranged in N rows in the second direction, M is an integer larger than or equal to 3, and N is an integer larger than or equal to 0. According to the transverse excitation bulk acoustic wave resonator, the mechanical quality factor of the resonator can be improved, and the stray mode can be suppressed.

Description

Technical Field

[0001] The utility model relates to the technical field of resonators, and in particular to a transversely excited bulk acoustic wave resonator and a filter. Background Art

[0002] With the rapid development of wireless communication technology, the market has put forward requirements for RF filters such as low loss, miniaturization, integration, low power consumption, and high performance. As the core component of RF filters, transversely excited bulk acoustic wave resonators have become a research hotspot in recent years due to their small size and the ability to achieve single-chip multi-band integration.

[0003] The traditional transversely excited bulk acoustic wave resonator is composed of a piezoelectric layer and a forked electrode structure located on the surface of the piezoelectric layer. Although the laterally excited resonator can adjust the operating frequency by adjusting the spacing between adjacent electrode strips of the forked electrode, due to the high mechanical loss and anchor loss on both sides of the collector area of ​​the forked electrode, the mechanical quality factor of the laterally excited bulk acoustic wave resonator is low, which makes it difficult to meet the market demand for low loss. In addition, the laterally excited bulk acoustic wave resonator has obvious spurious modes, which will cause the RF filter to produce more in-band ripples and degrade the filtering effect of the filter. Therefore, how to solve the above problems to improve the performance of the RF filter is important and meaningful. Utility Model Content

[0004] The utility model aims to provide a transversely excited bulk acoustic wave resonator and a filter, which can effectively improve the mechanical quality factor of the resonator and suppress the stray modes generated during operation.

[0005] The embodiment of the utility model is achieved as follows:

[0006] In one aspect of the utility model, a transversely excited bulk acoustic wave resonator is provided, the transversely excited bulk acoustic wave resonator comprises a substrate, an insulating layer arranged on the substrate, a piezoelectric layer arranged on the insulating layer, and an interdigital electrode arranged on the piezoelectric layer; the interdigital electrode comprises two electrode structures arranged opposite to each other, the electrode structure comprises a bus and a plurality of electrode strips connected in parallel along a first direction to the same side of the bus, and a gap region is provided between the electrode strips of one electrode structure and the bus of another electrode structure; the transversely excited bulk acoustic wave resonator further comprises a phononic crystal structure located on the substrate and arranged in the gap region, the phononic crystal structure comprises a plurality of phononic crystal parts arranged in a matrix, the plurality of phononic crystal parts are arranged into M columns along a first direction, and into N rows along a second direction, the first direction is the same as the arrangement direction of the two electrode structures, the second direction is the same as the arrangement direction of the plurality of electrode strips of the electrode structure, M is an integer greater than or equal to 3, and N is an integer greater than or equal to 0. The transversely excited bulk acoustic wave resonator can effectively improve the mechanical quality factor of the resonator and suppress the stray modes generated when it is working.

[0007] Optionally, the phononic crystal portion is a metal strip structure formed on the piezoelectric layer.

[0008] Optionally, the thickness of the metal strip structure is the same as the thickness of the electrode strip.

[0009] Optionally, N is equal to 0, and both opposite ends of the metal strip structure are connected to a connecting strip, wherein the connecting strip is an electrode strip close to the end of the metal strip structure along the second direction.

[0010] Optionally, the phononic crystal portion is a through-hole structure recessed in the piezoelectric layer.

[0011] Optionally, the through-hole structure is filled with a filling material, and the filling material is any one of PDMS, Au, AlN, SiO2, W, Mo, ScAlN, GaO, SiN, and Al, or a composite material composed of at least two of the materials.

[0012] Optionally, the depth of the through hole structure is the same as the thickness of the piezoelectric layer.

[0013] Optionally, the length of the phononic crystal structure along the second direction is greater than or equal to the length of the electrode strip along the second direction; and / or, the spacing between any two adjacent columns of phononic crystal portions is the same, and the length of any two adjacent columns of phononic crystal portions along the second direction is the same; and / or, the spacing between any two adjacent rows of phononic crystal portions is the same, and the length of any two adjacent rows of phononic crystal portions along the second direction is the same.

[0014] Optionally, the geometric center of the phononic crystal structure is located on a central axis of the corresponding electrode strip extending along the first direction.

[0015] Another aspect of the present invention provides a filter, which includes the above-mentioned transversely excited bulk acoustic wave resonator.

[0016] The beneficial effects of the utility model include:

[0017] The laterally excited bulk acoustic wave resonator provided by the present application is configured by setting a phononic crystal structure in the gap region, and configuring the phononic crystal structure to include a plurality of phononic crystal portions arranged in an N×M matrix. In this way, the position of the phononic crystal bandgap can be regulated by changing the size of the phononic crystal portion along the first direction and the spacing between two adjacent phononic crystal portions along the first direction, so that the resonant frequency and the anti-resonant frequency of the resonator are contained in the bandgap of the phononic crystal structure, thereby realizing reflection of the lateral leakage energy of the main resonant mode, thereby improving the mechanical quality factor of the resonator; for the stray mode whose frequency is within the conduction band of the phononic crystal structure, its vibration energy will be dissipated to the substrate through lateral leakage, and will not be blocked by the phononic crystal structure, thereby achieving the effect of suppressing the stray mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 One of the structural schematic diagrams of the transversely excited bulk acoustic wave resonator provided in some embodiments of the utility model;

[0020] Figure 2 for Figure 1 sectional view of

[0021] Figure 3 for Figure 1 The band diagram of the laterally excited bulk acoustic wave resonator is provided;

[0022] Figure 4 A second structural schematic diagram of a transversely excited bulk acoustic wave resonator provided in some embodiments of the utility model;

[0023] Figure 5 for Figure 4 sectional view of

[0024] Figure 6 is the impedance curve of the traditional transversely excited bulk acoustic wave resonator;

[0025] Figure 7 The Bode_Q curve of the traditional transversely excited bulk acoustic wave resonator;

[0026] Figure 8 Impedance curve diagram of a transversely excited bulk acoustic wave resonator provided in some embodiments of the utility model;

[0027] Fig. 9 Bode_Q curve diagram of a transversely excited bulk acoustic wave resonator provided in some embodiments of the utility model;

[0028] Fig.10 A third structural schematic diagram of a transversely excited bulk acoustic wave resonator provided in some embodiments of the utility model;

[0029] Fig.11 The fourth structural schematic diagram of the transversely excited bulk acoustic wave resonator provided in some embodiments of the utility model.

[0030] Icon: 10-substrate; 20-insulating layer; 30-piezoelectric layer; 41-electrode structure; 411-bus; 412-electrode strip; a-first direction; b-second direction; 50-gap region; 60-phononic crystal structure; 61-phononic crystal portion; 501-first bandgap; 502-second bandgap; 503-third bandgap; 504-fourth bandgap. DETAILED DESCRIPTION

[0031] The embodiments set forth below represent information necessary to enable those skilled in the art to practice the embodiments, and illustrate the best mode for practicing the embodiments. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present invention, and will recognize the applications of these concepts not specifically proposed herein. It should be understood that these concepts and applications are within the scope of the present invention and the appended claims.

[0032] It should be understood that although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to divide an element from another element. For example, without departing from the scope of the present invention, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] It should be understood that when an element (such as a layer, region or substrate) is referred to as "on another element" or "extending onto another element", it can be directly on another element or directly extended onto another element, or there can also be an intervening element. On the contrary, when an element is referred to as "directly on another element" or "directly extending onto another element", there is no intervening element. Similarly, it should be understood that when an element (such as a layer, region or substrate) is referred to as "on another element" or "extending onto another element", it can be directly on another element or directly extended onto another element, or there can also be an intervening element. On the contrary, when an element is referred to as "directly on another element" or "extending directly onto another element", there is no intervening element. It should also be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to another element, or there can be an intervening element. On the contrary, when an element is referred to as "directly connected" or "directly coupled" to another element, there is no intervening element.

[0034] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element, layer or region to another element, layer or region as shown in the figures. It should be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0035] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the utility model. As used herein, unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" are intended to include the plural forms as well. It should also be understood that when used herein, the term "comprising" indicates the presence of the features, integers, steps, operations, elements and / or parts, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups of the above.

[0036] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which the utility model belongs. It should also be understood that the terms used in this article should be interpreted as having the same meaning as they do in this specification and the relevant field, and should not be interpreted in an idealized or overly formal sense, unless clearly defined in this article.

[0037] Please refer to Figure 1 and Figure 2 The present embodiment provides a lateral excitation bulk acoustic wave resonator, which includes a substrate 10, an insulating layer 20 disposed on the substrate 10, a piezoelectric layer 30 disposed on the insulating layer 20, and interdigital electrodes disposed on the piezoelectric layer 30; the interdigital electrodes include two oppositely disposed electrode structures 41, the electrode structure 41 includes a bus 411 and a plurality of electrode strips 412 connected in parallel to the same side of the bus 411 along a first direction a, the plurality of electrode strips 412 of the two electrode structures 41 are alternately disposed, and the electrode strips 412 of one electrode structure 41 are alternately disposed, and the electrode strips 412 of the other electrode structure 41 are alternately disposed. There is a gap area 50 between the busbars 411 of the structure 41; the lateral excitation bulk acoustic wave resonator also includes a phononic crystal structure 60 located on the substrate 10 and arranged in the gap area 50, the phononic crystal structure 60 includes a plurality of phononic crystal parts 61 arranged in a matrix, the plurality of phononic crystal parts 61 are arranged in M ​​columns along the first direction a, and arranged in N rows along the second direction b, the first direction a is the same as the arrangement direction of the two electrode structures 41, the second direction b is the same as the arrangement direction of the plurality of electrode strips 412 of the electrode structure 41, M is an integer greater than or equal to 3, and N is an integer greater than or equal to 0. The lateral excitation bulk acoustic wave resonator can effectively improve the mechanical quality factor of the resonator and suppress the stray modes generated during its operation.

[0038] The material of the substrate 10 may be silicon, sapphire, diamond, polysilicon, silicon nitride, etc., but is not limited thereto. The material of the insulating layer 20 may be silicon dioxide, etc.

[0039] The piezoelectric layer 30 is located on the insulating layer 20 , and the material of the piezoelectric layer 30 may be, but is not limited to, AlN, LiNbO 3 , ScAlN, LiTaO 3 , PVDF, GaO and the like.

[0040] The interdigitated electrodes are disposed on the piezoelectric layer 30. Figure 1 As shown, the interdigitated electrode includes two electrode structures 41, and the two electrode structures 41 are arranged along a first direction a, corresponding to Figure 1 In the middle Figure 1 Horizontal direction.

[0041] Each electrode structure 41 includes a bus bar 411 and a plurality of electrode strips 412. The plurality of electrode strips 412 are arranged along a second direction b, which is perpendicular to the first direction a. Figure 1 The middle direction is the vertical direction. One end of the plurality of electrode strips 412 is connected to the bus bar 411 respectively.

[0042] It should be noted that, in this embodiment, a gap region 50 is formed between the electrode strips 412 of one electrode structure 41 and the busbars 411 of another electrode structure 41. Figure 1 The size of the gap area 50 along the first direction a is not limited in this application, and those skilled in the art can determine it as needed.

[0043] In this embodiment, the electrode strips 412 and the busbars 411 of the electrode structure 41 are made of the same material. For example, the material of the electrode strips 412 and the busbars 411 may be, but is not limited to, Al, Mo, Au, Ti, W, Cu, and alloys thereof.

[0044] The phononic crystal structure 60 is located in the gap region 50. In the present embodiment, the phononic crystal structure 60 includes a plurality of phononic crystal portions 61, which are arranged in an N×M matrix, wherein the phononic crystal structure 60 has at least three columns along the first direction a. Figure 1 , Figure 4 , Fig.10 and Fig.11 shown.

[0045] It should be noted that the shape of the phononic crystal portion 61 may be rectangular, circular, elliptical or rounded rectangular, etc. The present application does not limit the specific shape of the phononic crystal portion 61 .

[0046] In addition, it should be noted that the phononic crystal structure 60 may be located on the piezoelectric layer 30 , or may be located inside the piezoelectric layer 30 with its upper end surface flush with the upper surface of the piezoelectric layer 30 .

[0047] The present application forms a phononic crystal structure 60 in the gap region 50. The phononic crystal is a special structure in which parameters such as elastic constants, sound velocity or acoustic impedance show periodic changes, which can produce a bandgap completely or in a specific direction. In the bandgap, elastic waves of a specific frequency and a specific direction cannot propagate. The periodic change of the metallization rate in the gap region 50 will cause the sound velocity of the body acoustic wave in this area to change periodically, so it can be used as a phononic crystal to produce a blocking effect on sound waves of a specific frequency (i.e., in the bandgap) without affecting the propagation of sound waves of other frequencies. In the design process of the resonator, the position of the phononic crystal bandgap can be adjusted by changing the size of the phononic crystal portion 61 along the first direction a and the spacing between two adjacent phononic crystal portions 61 along the first direction a. By adjusting and controlling the resonant frequency and anti-resonant frequency of the resonator to be contained in the forbidden band of the phononic crystal structure 60, the lateral leakage energy of the main resonant mode is reflected, thereby increasing the Q value of the device; for the stray mode whose frequency is within the conduction band of the phononic crystal structure 60, its propagation will not be blocked by the phononic crystal structure 60, and its vibration energy will be dissipated to the substrate 10 through lateral leakage, thereby achieving the effect of suppressing the stray mode.

[0048] In summary, the laterally excited bulk acoustic wave resonator provided by the present application is configured by setting a phononic crystal structure 60 in the gap region 50, and configuring the phononic crystal structure 60 to include a plurality of phononic crystal portions 61 arranged in an N×M matrix. In this way, the position of the phononic crystal bandgap can be regulated by changing the size of the phononic crystal portion 61 along the first direction a and the spacing between two adjacent phononic crystal portions 61 along the first direction a, so that the resonant frequency and anti-resonant frequency of the resonator are contained in the bandgap of the phononic crystal structure 60, thereby realizing reflection of the lateral leakage energy of the main resonant mode, thereby improving the mechanical quality factor of the resonator; for the stray mode whose frequency is within the conduction band of the phononic crystal structure 60, its vibration energy will be dissipated to the substrate 10 through lateral leakage, and will not be blocked by the phononic crystal structure 60, thereby achieving the effect of suppressing the stray mode.

[0049] The phononic crystal structure 60 may be located on the piezoelectric layer 30, or may be located in the piezoelectric layer 30 with the upper end surface flush with the upper surface of the piezoelectric layer 30. For example, in a first feasible implementation, the phononic crystal portion 61 is a metal strip structure formed on the piezoelectric layer 30, see Figure 1 and Figure 2 , Fig.11 .

[0050] The unit cell structure of the phononic crystal structure 60 may be formed on the piezoelectric layer 30 , and a plurality of phononic crystal portions 61 may be formed by patterning.

[0051] It should be noted that, in this implementation, the plurality of phononic crystal portions 61 may be distributed in one dimension (ie, the plurality of phononic crystal portions 61 include M columns and zero rows, such as Figure 1 As shown), it can also be distributed in two dimensions (ie, the plurality of phononic crystal portions 61 include M columns and N rows), which is not limited in the present application.

[0052] When the phononic crystal portion 61 is a metal strip structure formed on the piezoelectric layer 30 , in order to better reflect the lateral leakage energy of the main resonance mode, optionally, the thickness of the metal strip structure is the same as the thickness of the electrode strip 412 .

[0053] In addition, when the phononic crystal portion 61 is a metal strip structure formed on the piezoelectric layer 30, in one implementation, both opposite ends of the metal strip structure are spaced apart from the connecting strip, wherein the connecting strip is an electrode strip 412 close to the end of the metal strip structure along the second direction b, such as Figure 1 In short, in this implementation, the two opposite ends of the metal strip structure and the electrode strip 412 closest thereto are not in contact, and the unit cell structure of the phononic crystal structure 60 is formed on the piezoelectric layer 30, and a plurality of discrete suspension structures (the suspension structure here is the phononic crystal portion 61) are formed by patterning.

[0054] When the plurality of metal strip structures are distributed in one dimension and the two opposite ends of the metal strip structure are not in contact with the electrode strip 412, please refer to Figure 3 , Figure 3 Each curve in the figure represents a dispersion curve of a vibration mode. It can be seen that this phononic crystal structure 60 has four omnidirectional forbidden bands (the first forbidden band 501, the second forbidden band 502, the third forbidden band 503, and the fourth forbidden band 504), and no vibration mode exists within these frequency ranges. The third forbidden band 503 just contains Figure 3 At the resonance point and anti-resonance point of the resonator shown, the introduction of the phononic crystal structure 60 provided in the present application can effectively reflect the main mode sound wave, thereby improving the Q value of the resonator. At other positions in the energy band diagram, various vibration modes of sound waves may exist, so the vibration energy of the stray mode within the frequency range can be dissipated into the substrate 10 through the phononic crystal, and the resonance intensity of the stray mode will be reduced.

[0055] In another implementation, N is equal to 0, and both opposite ends of the metal strip structure are connected to a connecting strip, wherein the connecting strip is an electrode strip 412 close to the end of the metal strip structure along the second direction b, such as Fig.11In this implementation, the two opposite ends of the metal strip structure are connected to the electrode strips 412 disposed closest to the ends thereof.

[0056] In this way, a plurality of metal strip structures are deposited on the piezoelectric layer 30 in the gap region 50, and the plurality of metal strip structures are arranged along the first direction a. Each metal strip structure is connected to the electrode strip 412 adjacent to the electrode strip 412 along the second direction b, and serves as a short-circuit reflector to reflect the acoustic waves leaked laterally. In this manner, the width (dimension along the first direction a) of each metal strip structure should be consistent, and the number should be no less than 3.

[0057] It should be noted that when the phononic crystal portion 61 is a metal strip structure formed on the piezoelectric layer 30, no matter how Figure 1 As shown in the discrete suspension setup, or as Fig.11 As shown in the short-circuit design, the material of the metal strip structure can be the same as or different from the material of the interdigital electrodes. When different, metals with higher density such as Mo, Cu, Au, etc. are preferred.

[0058] For example, in a second feasible implementation, the phononic crystal portion 61 may also be a through-hole structure recessed in the piezoelectric layer 30, such as Figure 4 and Figure 5 , Fig.10 shown.

[0059] That is to say, in this implementation, the phononic crystal portion 61 is a through-hole structure disposed in the piezoelectric layer 30 .

[0060] Among them, optionally, the above-mentioned through-hole structure may be filled with air, or may also be filled with a filling material, and the filling material is any one of PDMS, Au, AlN, SiO2, W, Mo, ScAlN, GaO, SiN, Al, or a composite material composed of at least two materials.

[0061] The present application fills other materials with different acoustic impedance from the piezoelectric material in the through-hole structure. These materials have acoustic impedances that are very different (larger or smaller) from the material of the piezoelectric layer 30, thereby generating a phononic crystal structure 60 with a larger forbidden band gap. This method can improve the power carrying capacity of the device.

[0062] Optionally, in this embodiment, the depth of the through hole structure is the same as the thickness of the piezoelectric layer 30 .

[0063] The plurality of through-hole structures may be distributed in one dimension (ie, the plurality of through-hole structures include M columns and zero rows, such as Figure 4 and Figure 5 As shown), it can also be distributed in two dimensions (ie, multiple through-hole structures include M columns and N rows, as shown Fig.10 This application does not limit this.

[0064] It should be noted that, compared with one-dimensional phononic crystals, two-dimensional phononic crystals have a greater barrier effect on the propagation of acoustic waves in the forbidden band in a wider propagation direction, and can more effectively improve the mechanical quality factor of the device. In order to achieve sufficient reflection capability, when a two-dimensionally distributed phononic crystal structure 60 is used, the through-hole structure or metal strip structure should be no less than 3 columns along the first direction a, and no less than 3 rows along the second direction b, and the size of all through-hole structures or metal strip structures should be consistent.

[0065] Figure 6 and Figure 7 The test data of the traditional structure lateral excitation bulk acoustic wave resonator with typical structural parameters are shown. Figure 6 The impedance curve of the traditional transversely excited BAW resonator is shown in Figure 1. There is an obvious spurious mode at 590MHz, and the impedance ratio of the parallel resonance to the series resonance of the main mode (near 635MHz) is 50.67dB. Figure 7 The Bode_Q curve of the traditional transversely excited bulk acoustic wave resonator is obtained by fitting the MBVD circuit model. max 1105, Q p It is 682.

[0066] Figure 8 and Fig. 9 This is the test data of the transversely excited bulk acoustic wave resonator of this application. Among them, Figure 8 The impedance curve is Figure 4 and Figure 5 From the impedance curve of the transversely excited bulk acoustic wave resonator of the structure shown in the figure, it can be seen that the spurious mode at 590MHz is significantly weakened and the resonance intensity is reduced; the impedance ratio of the resonance point to the anti-resonance point of the main mode (633MHz-641MHz) is 64.74dB. Fig. 9 This is the Bode_Q curve. The mechanical quality factor Q of the resonator is obtained by fitting the MBVD circuit model. max is 2647, Q p 1520, compared with the traditional transverse excitation bulk acoustic wave resonator, its mechanical quality factor Q max and Q p The k of the resonator is increased by about 2.5 times, and the spurious mode is significantly weakened. In addition, the structure of the present application will not reduce the k of the resonator. eff 2 .

[0067] In addition, it should be noted that, for the laterally excited bulk acoustic wave resonator provided in the present application, regardless of whether the phononic crystal portion 61 is a metal strip structure or a through-hole structure, or the phononic crystal structure 60 is distributed in one dimension or in two dimensions, the length of the phononic crystal structure 60 along the second direction b can be greater than or equal to the length of the electrode strip 412 along the second direction b.

[0068] In addition, the spacing between any two adjacent columns of phononic crystal parts 61 can be the same, and the lengths of any two adjacent columns of phononic crystal parts 61 along the second direction b are the same. The spacing between any two adjacent rows of phononic crystal parts 61 are the same, and the lengths of any two adjacent rows of phononic crystal parts 61 along the second direction b are the same.

[0069] In this embodiment, the lengths of multiple phononic crystal sections 61 along the first direction a can be the same, the lengths of multiple phononic crystal sections 61 along the second direction b can be the same, the spacing between two adjacent phononic crystal sections 61 along the first direction a can be the same, and the spacing between two adjacent phononic crystal sections 61 along the second direction b can also be the same. Thus, a periodic change of electrode metallization (the material of the phononic crystal section 61 is metal) can be constructed in the gap region 50. Among them, the part covered with metal has a lower body acoustic wave velocity, while the velocity at other positions is higher, thereby forming a phononic crystal structure 60. Among them, the specific number of columns of the phononic crystal structure 60 can be determined according to the size of its periodic length, and generally should be no less than three.

[0070] For better reflection effect, the geometric center of the phononic crystal structure 60 is optionally located on the central axis of the corresponding electrode strip 412 extending along the first direction a. In other words, the geometric center of the phononic crystal structure 60 should be located on the perpendicular bisector of the width direction of the electrode strip 412 arranged parallel to it in the first direction a. Figure 1 As shown, the width direction of the electrode strip 412 is the second direction b.

[0071] Another aspect of the present invention provides a filter, which includes the above-mentioned transversely excited bulk acoustic wave resonator. Since the specific structure and technical effects of the transversely excited bulk acoustic wave resonator have been described and explained in detail in the previous text, the present application will not repeat them here. Since the filter includes the transversely excited bulk acoustic wave resonator with the phononic crystal structure 60, it can effectively improve the mechanical quality factor of the resonator and suppress the stray modes generated when it is working.

[0072] The above description is only an optional embodiment of the utility model and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

[0073] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present utility model will not further describe various possible combinations.

Claims

1. A transversely excited bulk acoustic wave resonator, characterized in that: The invention comprises a substrate, an insulating layer disposed on the substrate, a piezoelectric layer disposed on the insulating layer, and an interdigital electrode disposed on the piezoelectric layer; the interdigital electrode comprises two electrode structures disposed opposite to each other, the electrode structure comprises a bus and a plurality of electrode strips connected in parallel along a first direction to the same side of the bus, and a gap region is provided between the electrode strip of one of the electrode structures and the bus of another of the electrode structures; The laterally excited bulk acoustic wave resonator also includes a phononic crystal structure located on the substrate and arranged in the gap region, the phononic crystal structure includes a plurality of phononic crystal portions arranged in a matrix, the plurality of phononic crystal portions are arranged into M columns along a first direction and into N rows along a second direction, the first direction is the same as an arrangement direction of the two electrode structures, the second direction is the same as an arrangement direction of the plurality of electrode strips of the electrode structure, M is an integer greater than or equal to 3, and N is an integer greater than or equal to 0.

2. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The phononic crystal portion is a metal strip structure formed on the piezoelectric layer.

3. The transversely excited bulk acoustic wave resonator according to claim 2, characterized in that: The thickness of the metal strip structure is the same as the thickness of the electrode strip.

4. The transversely excited bulk acoustic wave resonator according to claim 2, characterized in that: The N is equal to 0, and both opposite ends of the metal strip structure are connected to a connecting strip, wherein the connecting strip is the electrode strip close to the end of the metal strip structure along the second direction.

5. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The phononic crystal portion is a through-hole structure recessed in the piezoelectric layer.

6. The transversely excited bulk acoustic wave resonator according to claim 5, characterized in that: The depth of the through hole structure is the same as the thickness of the piezoelectric layer.

7. The transversely excited bulk acoustic wave resonator according to any one of claims 1 to 6, characterized in that: The length of the phononic crystal structure along the second direction is greater than or equal to the length of the electrode strip along the second direction; and / or, the spacing between any two adjacent columns of the phononic crystal parts is the same, and the lengths of any two adjacent columns of the phononic crystal parts along the second direction are the same; And / or, the spacing between any two adjacent rows of the phononic crystal parts is the same, and the lengths of any two adjacent rows of the phononic crystal parts along the second direction are the same.

8. The transversely excited bulk acoustic wave resonator according to claim 7, characterized in that: The geometric center of the phononic crystal structure is located on the central axis of the corresponding electrode strip extending along the first direction.

9. A filter, characterized in that: A transversely excited bulk acoustic wave resonator comprising any one of claims 1 to 8.

Images