Acoustic resonator, filter and electronic device

Abstract

Provided in the present application are an acoustic resonator, a filter and an electronic device. The acoustic resonator comprises a substrate layer, a piezoelectric transducer structural layer and an energy regulation layer, wherein the piezoelectric transducer structural layer is arranged on one side of the substrate layer; the energy regulation layer is arranged between the substrate layer and the piezoelectric transducer structural layer, and the energy regulation layer comprises a plurality of confinement slots, each confinement slot at least passing through the surface of the energy regulation layer facing the piezoelectric transducer structural layer. In the present application, by means of the confinement slots which are spaced apart from each other and pass through the surface of the energy regulation layer facing the piezoelectric transducer structural layer, acoustic wave energy is concentrated in the piezoelectric transducer structural layer, thereby reducing the leakage of the acoustic wave energy towards the substrate layer, and facilitating the increase of an electromechanical coupling coefficient of the acoustic resonator; then, by means of the energy regulation layer among the adjacent confinement slots, the piezoelectric transducer structural layer is supported, such that the collapse of the piezoelectric transducer structural layer is avoided, and the situation where the power capacity of the acoustic resonator decreases is reduced, thereby increasing the power capacity and electromechanical coupling coefficient of the acoustic resonator.

Description

Acoustic resonator, filter and electronic equipment

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on December 27, 2023, with application number 202311834252.X and application name “An Acoustic Resonator, Filter and Electronic Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of semiconductor technology, and in particular to an acoustic resonator, a filter, and an electronic device. Background Art

[0003] With the development of communication technology, in order to meet the needs of massive data and real-time high-speed transmission in communication networks, it is necessary to increase the channel bandwidth in high-speed communication networks. Usually, large-bandwidth filters are used in high-speed communication networks to increase the channel bandwidth. The resonator, as a filter design unit, is the main component for increasing the filter bandwidth.

[0004] The power capacity and electromechanical coupling coefficient of the resonator will affect the bandwidth design of the filter. Therefore, in order to increase the channel bandwidth of the filter, improving the power capacity and electromechanical coupling coefficient of the resonator is the current research focus and difficulty of the resonator. Summary of the Invention

[0005] The present application provides an acoustic resonator, a filter, and an electronic device for improving the power capacity and electromechanical coupling coefficient of the resonator, thereby improving the communication performance of the filter.

[0006] In a first aspect, an acoustic resonator is provided, comprising a base layer, a piezoelectric transducer structure layer and an energy regulation layer; the piezoelectric transducer structure layer is arranged on one side of the base layer; the energy regulation layer is arranged between the base layer and the piezoelectric transducer structure layer, and the energy regulation layer comprises a plurality of restraining grooves, each of the restraining grooves at least passing through the surface of the energy regulation layer facing the piezoelectric transducer structure layer.

[0007] The acoustic resonator provided by the present application has an energy regulation layer located on the side of the piezoelectric transducer structure layer facing away from the electrode layer, and the confinement grooves penetrate the surface of the energy regulation layer toward the piezoelectric transducer structure layer. Thus, during the propagation of acoustic wave energy, the multiple confinement grooves of the energy regulation layer can concentrate energy in the piezoelectric transducer structure layer, reducing the leakage of acoustic wave energy toward the substrate layer, which helps to improve the electromechanical coupling coefficient of the acoustic resonator. The piezoelectric transducer structure layer is then supported by the portion of the energy regulation layer between adjacent confinement grooves, preventing the piezoelectric transducer structure layer from collapsing, reducing the power capacity reduction of the acoustic resonator, ensuring the power capacity of the acoustic resonator, and improving the performance of the acoustic resonator. As a result, the power capacity and electromechanical coupling coefficient of the acoustic resonator are improved, thereby helping to improve the performance of the filter.

[0008] In some embodiments, each of the confining grooves further extends through a surface of the energy regulation layer facing away from the piezoelectric transducer structure layer. This arrangement facilitates the concentration of acoustic wave energy on one side of the piezoelectric transducer structure layer after entering the confining grooves, when the confining grooves extend through a surface of the energy regulation layer facing away from the piezoelectric transducer structure layer.

[0009] In some embodiments, the piezoelectric transduction structure layer includes a piezoelectric material layer and an interdigital transduction structure located on the side of the piezoelectric material layer facing away from the base layer; the interdigital transduction structure includes a plurality of first interdigital electrodes and a plurality of second interdigital electrodes that are opposite and cross-arranged along a first direction, and the first direction is parallel to the base layer; the confinement groove extends along one side of the energy regulation layer on two opposite sides in the second direction to the other side, and the second direction is parallel to the base layer, and the second direction is parallel to or perpendicular to the first direction.

[0010] This arrangement, through the interdigitated arrangement of the first and second interdigital electrodes, allows, on the one hand, acoustic wave energy to reflect back and forth within the piezoelectric material layer, forming oscillations and achieving the transduction function of the acoustic resonator. Furthermore, this interdigitated arrangement increases the distribution ratio of the first and second interdigital electrodes on the piezoelectric material layer, reducing the area occupied by the first and second interdigital electrodes, making the distribution of the first and second interdigital electrodes more compact and facilitating a reduction in the volume of the acoustic resonator.

[0011] In some embodiments, each of the constraining grooves extends in a direction parallel to the second direction or at an acute angle of less than 60° to the second direction. This arrangement facilitates forming constraining grooves extending in the same direction using the second direction as a reference direction when machining the energy regulation layer, thereby facilitating the formation of neatly arranged constraining grooves.

[0012] In some embodiments, the confining groove is wavy, with the end-to-end line extending along the second direction. This configuration increases the space occupied by the confining groove on the energy regulation layer, thereby increasing the space available for the confining groove to concentrate acoustic wave energy on the piezoelectric material layer, thereby enhancing the confining groove's ability to concentrate acoustic wave energy.

[0013] In some embodiments, a portion of the constraining grooves extends along a second direction, while another portion of the constraining grooves extends along a third direction, where the second direction is non-parallel to the third direction. This arrangement allows one portion of the constraining grooves to extend in a different direction than another portion of the constraining grooves, facilitating machining along two different directions on the energy regulation layer, thereby facilitating adjustment of the machining direction of the energy regulation layer and improving the ease of machining the constraining grooves.

[0014] In some embodiments, the plurality of confining slots include a plurality of first slots and a plurality of second slots, wherein the first slots extend from one side of the energy regulation layer in a second direction to the other side thereof; and the second slots extend from one side of the energy regulation layer in a third direction to the other side thereof, wherein the third direction is not parallel to the second direction. This arrangement allows the plurality of first slots and the plurality of second slots to extend in different directions and to intersect with each other, thereby increasing the distribution of the confining slots on the energy regulation layer and the proportion of the confining slots on the energy regulation layer, thereby enhancing the concentrating effect of the confining slots on acoustic wave energy.

[0015] In some embodiments, a Bragg reflector layer is further included, located between the substrate and the energy regulation layer. This arrangement allows the Bragg reflector layer to better reflect acoustic wave energy to the piezoelectric material layer, allowing the confining grooves of the energy regulation layer to concentrate the acoustic wave energy in the piezoelectric material layer, further improving the electromechanical coupling coefficient of the acoustic resonator.

[0016] In some embodiments, the energy regulation layer further includes a separator that divides the energy regulation layer into a plurality of confining grooves, with the separator occupying 1% to 99% of the area of ​​the energy regulation layer. This configuration utilizes the separator to support the piezoelectric transducer structure layer, preventing collapse of the piezoelectric transducer structure layer and reducing the power capacity reduction of the acoustic resonator, thereby ensuring the power capacity of the acoustic resonator.

[0017] In some embodiments, the energy regulation layer comprises at least one of SiO2, SiOC, Si3N4, AlN, Pt, Mo, W, and HfO2. This configuration allows the support to have a higher reflection coefficient, thereby enhancing the effect of the engineering material layer on limiting the energy of acoustic waves.

[0018] In a second aspect, a method for preparing an acoustic resonator is provided, which includes providing a base layer, forming a piezoelectric transducer structure layer on one side of the base layer, and forming an energy regulation layer between the base layer and the piezoelectric transducer structure layer, wherein the energy regulation layer includes a plurality of restraining grooves, and each restraining groove at least penetrates the surface of the energy regulation layer toward the piezoelectric transducer structure layer.

[0019] The acoustic resonator formed based on the method for preparing the acoustic resonator provided in the embodiment of the present application includes the acoustic resonator as described above, and therefore has all the beneficial effects of the above-mentioned acoustic resonator, which will not be repeated here.

[0020] In a third aspect, a filter is provided, comprising a plurality of cascaded resonators, wherein at least one resonator in the plurality of cascaded resonators is an acoustic resonator in any one of the above embodiments.

[0021] In the filter provided in this embodiment, since the acoustic resonator in any of the above embodiments can be used, a filter with a larger channel bandwidth can be realized by utilizing the high electromechanical coupling coefficient and large power capacity of the acoustic resonator.

[0022] In a fourth aspect, an electronic device is provided, comprising a filter and a circuit board, wherein the filter is disposed on the circuit board, and the filter is the filter described in the second aspect. Since the electronic device has the same technical effects as the acoustic resonator provided in the first aspect, reference may be made to the relevant description of the first aspect, and no further elaboration is given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a structural block diagram of an electronic device provided by this embodiment;

[0024] FIG2 is a cross-sectional schematic diagram of a transversely excited bulk acoustic wave resonator provided in this embodiment;

[0025] FIG3 is an admittance curve diagram of the transversely excited bulk acoustic wave resonator provided in this embodiment;

[0026] FIG4 is a three-dimensional structural diagram of an acoustic resonator provided in an embodiment of the present application;

[0027] FIG5 is a schematic cross-sectional view of the acoustic resonator provided in this embodiment in the XZ direction;

[0028] FIG6 is a three-dimensional structural diagram of an acoustic resonator provided in an embodiment of the present application when the first direction and the second direction are parallel;

[0029] FIG7 is a schematic cross-sectional view of the acoustic resonator provided in this embodiment in the XZ direction;

[0030] FIG8 is a schematic cross-sectional view of a restraining groove provided in this embodiment, wherein the cross-sectional shape in the XY direction is a straight strip;

[0031] FIG9 is a cross-sectional schematic diagram of a constraining groove provided in this embodiment, wherein the cross-sectional shape in the XY direction is wavy;

[0032] FIG10 is a three-dimensional structural diagram of the acoustic resonator provided by this embodiment without a Bragg reflection layer, in which the second direction is perpendicular to the first direction;

[0033] FIG11 is a three-dimensional structural diagram of the acoustic resonator provided by this embodiment in the absence of a Bragg reflection layer, where the second direction is parallel to the first direction;

[0034] FIG12 is a three-dimensional structural diagram of an acoustic resonator provided in this embodiment in which confining grooves are formed by etching in the second and third directions;

[0035] FIG13 is a schematic cross-sectional view of the second and third directions of the restraining groove provided in this embodiment;

[0036] FIG14 is a cross-sectional schematic diagram of a partition provided in this embodiment, in which the cross-sectional shape of the partition on the XY plane is circular;

[0037] FIG15 is a graph showing the relationship between frequency and quality factor Q of an acoustic resonator according to this embodiment;

[0038] FIG16 is a graph showing the electromechanical coupling coefficient of the acoustic resonator provided in this embodiment when etching is performed along the X direction and the Y direction;

[0039] FIG17 is a slowness curve diagram of the acoustic resonator provided in the present embodiment in the XY direction;

[0040] FIG18 is a comparison diagram of dispersion curves of the acoustic resonator provided in this embodiment;

[0041] FIG19 is a flow chart of the method for preparing the acoustic resonator provided in this embodiment. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0043] The terms "first," "second," and the like (if any) in the description and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions, e.g., a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or apparatus.

[0044] The following is a brief introduction to some concepts that may be involved in the embodiments of the present invention.

[0045] Electromechanical coupling coefficient K 2 : It is a key parameter of the resonator, the electromechanical coupling coefficient K 2 It can reflect the conversion efficiency between mechanical energy and electrical energy, the electromechanical coupling coefficient K of the resonator 2 It determines the difference between the series and parallel resonant frequencies of the resonator. When the resonator is used in the filter design, this difference directly determines the bandwidth of the filter. It can be considered that the electromechanical coupling coefficient K 2 The larger it is, the higher the conversion efficiency of the resonator and the better the performance.

[0046] Quality factor Q: represents the energy utilization rate of the device, that is, the ratio of the total energy received by the device to the energy dissipated in one vibration cycle. In the design of the filter, the electromechanical coupling coefficient K of the resonator constituting the filter is 2 The quality factor Q value is an important parameter.

[0047] Euler angles of piezoelectric materials: In bulk acoustic wave (BAW) resonators, Euler angles represent the crystallographic direction of the wafer surface normal and the reference plane direction that coincides with the BAW propagation direction. These Euler angles are also called cut angles.

[0048] Slowness characteristics, slowness curve: Slowness characteristics are usually characterized by slowness curves. Slowness characteristics are physical parameters that measure the propagation of waves in a medium. Slowness is the inverse of speed. Therefore, the propagation time of a wave is the distance the wave travels multiplied by the slowness of the medium.

[0049] This embodiment provides an electronic device 1000, which includes but is not limited to products such as radio frequency front-ends, filter amplification modules, etc., and may also include mobile phones, tablet computers, smart wearable products (for example, smart watches, smart bracelets), virtual reality (VR) devices, augmented reality (AR), drones, etc. Home electronic products include smart door locks, televisions, remote controls, refrigerators, rechargeable small household appliances (for example, soymilk machines, sweeping robots), etc. Car-mounted electronic products include car navigation systems, car-mounted high-density digital video discs (DVDs), etc. Financial terminal products include automated teller machines (ATMs), self-service terminals, etc. The embodiment of this application does not impose any special restrictions on the specific form of the above-mentioned communication equipment.

[0050] Refer to Figure 1, which is a structural block diagram of an electronic device 1000 provided in this embodiment. The electronic device 1000 may include a filter 100 and a circuit board 200. The filter 100 is arranged on the circuit board 200. Under the control of the circuit board 200, the filter 100 can perform conversion from electrical signal to acoustic signal (sound wave) to electrical signal. In the conversion process, the filter 100 can effectively filter out the frequency of a specific frequency point in the signal or the frequency outside the frequency point to obtain a signal of a specific frequency, or eliminate the signal after a specific frequency, so as to improve the working performance of the electronic device.

[0051] The current filter 100 is still mainly composed of relatively small acoustic filters, such as low-pass acoustic filters, high-pass acoustic filters, band-pass acoustic filters, band-stop acoustic filters, or active acoustic filters. Traditional acoustic filters are divided into two categories: surface acoustic wave filters (SAW) and bulk acoustic wave filters (BAW). SAW filters are mainly used for low frequencies, while BAW filters are mainly used for high frequencies above 2 GHz. However, for the new large-bandwidth frequency bands added by 5G communications, it is difficult for traditional SAW / BAW technology to meet the large-bandwidth filter design requirements of 5G communications. Therefore, the filter needs to meet the large-bandwidth design requirements.

[0052] In order to increase the bandwidth of the filter, the resonator as the filter design unit needs to have a larger electromechanical coupling coefficient. In this embodiment, the filter 100 may include multiple acoustic resonators 300 connected in series, or multiple acoustic resonators 300 connected in parallel, or a combination of series and parallel acoustic resonators 300.

[0053] The acoustic resonator 300 can be classified into a bulk acoustic wave resonator (BAW), a surface acoustic wave resonator (SAW), a transversely excited bulk acoustic wave resonator, and a solid-state mounted transversely excited bulk acoustic wave resonator.

[0054] For example, the laterally excited bulk acoustic wave resonator has a higher resonant frequency (>3.7GHz) than the traditional SAW resonator. Compared with the BAW resonator, it also has a larger bandwidth and can be used to make a large-bandwidth 5G or 6G filter. As shown in Figure 2, Figure 2 is a cross-sectional schematic diagram of the laterally excited bulk acoustic wave resonator provided in this embodiment. The laterally excited bulk acoustic wave resonator has a silicon substrate 110 and a piezoelectric layer 120 located above the silicon substrate 110. A cavity 130 is formed inside the silicon substrate 110 to confine the acoustic wave energy to the piezoelectric layer 120 through the cavity 130 to avoid leakage of the acoustic wave energy through the silicon substrate 110, thereby ensuring that the laterally excited bulk acoustic wave resonator obtains a higher quality factor Q.

[0055] To this end, refer to Figure 3, which is an admittance curve of the transversely excited bulk acoustic wave resonator provided in this embodiment. It can be seen from the admittance curve in Figure 3 that the horizontal axis represents frequency and the vertical axis represents Y11. The highest point of the curve is the resonance point, and the frequency corresponding to this point is the resonance frequency (resonance frequency, fr); the lowest point of the curve is the anti-resonance point, and the frequency corresponding to this point is the anti-resonance frequency (anti-resonance frequency, fa). The quality factor Q of the transversely excited bulk acoustic wave resonator can be reflected by the highest point and the lowest point. It can be seen from the smoothness of the curve that the spurious mode suppression of the transversely excited bulk acoustic wave resonator is more obvious, and it can be concluded from the peaks and troughs of the curve that the larger the bandwidth of the resonator, the larger the electromechanical coupling coefficient. Similarly, the larger the electromechanical coupling coefficient of the resonator, the larger the bandwidth.

[0056] However, as shown in FIG2 , due to the cavity 130 below the piezoelectric layer 120 of the lateral excitation bulk acoustic wave resonator, the piezoelectric layer film of the lateral excitation bulk acoustic wave resonator is prone to collapse after processing, resulting in the power capacity of the lateral excitation bulk acoustic wave resonator being lower than that of the traditional SAW and BAW. However, the solid-assembly type lateral excitation bulk acoustic wave resonator can solve its power capacity problem. However, the electromechanical coupling coefficient and quality factor Q of the resonator under the solid-assembly type lateral excitation bulk acoustic wave resonator structure will be greatly reduced compared to the traditional resonator structure. Therefore, refer to FIG3 , which is a curve showing the relationship between frequency and electromechanical coupling coefficient under the solid-assembly type lateral excitation bulk acoustic wave resonator. The horizontal axis is frequency, the vertical axis is electromechanical coupling coefficient, the solid line is the curve of electromechanical coupling coefficient and frequency of the traditional resonator, and the solid line is the curve of electromechanical coupling coefficient and frequency of the solid-assembly type lateral excitation bulk acoustic wave resonator. As can be seen from FIG3 , the higher the frequency, the more likely it is that the electromechanical coupling coefficient of the solid-assembly type lateral excitation bulk acoustic wave resonator will decrease instead. Therefore, the resonator currently has the problem that the power capacity and electromechanical coupling coefficient cannot be taken into account at the same time.

[0057] Based on at least the above two problems existing in the resonator, an embodiment of the present application provides an acoustic resonator 300, which is applied to the above-mentioned filter 100, can solve the problem that power capacity and electromechanical coupling coefficient cannot be taken into account at the same time, and suppress the spurious response of the acoustic resonator 300 to improve the quality factor Q of the acoustic resonator 300.

[0058] Referring to FIG. 4 , FIG. 4 is a three-dimensional structural diagram of an acoustic resonator 300 provided in an embodiment of the present application. The acoustic resonator 300 may include a base layer 310, a piezoelectric transducer structure layer 350, and an energy regulation layer 330. The piezoelectric transducer structure layer 350 is disposed on one side of the base layer 310. The energy regulation layer 330 is disposed between the base layer 310 and the piezoelectric transducer structure layer 350 and includes a plurality of confining grooves 331. Each confining groove 331 extends through at least the surface of the energy regulation layer 330 facing the piezoelectric transducer structure layer 350.

[0059] The energy regulation layer 330, through multiple confining grooves 331, concentrates acoustic wave energy in the piezoelectric transducer structure layer 350, helping to improve the electromechanical coupling coefficient of the acoustic resonator 300. By adjusting the number and spacing of the confining grooves 331, the main vibration mode of the acoustic resonator 300 can be controlled, flattening the slowness curve of the main vibration mode of the acoustic resonator 300 and suppressing the transverse mode of the acoustic resonator 300. This, in turn, suppresses spurious responses of the acoustic resonator 300, thereby improving the quality factor (Q) of the acoustic resonator 300. Furthermore, the portion of the energy regulation layer 330 between adjacent confining grooves 331 supports the piezoelectric transducer structure layer 350, improving its stability.

[0060] The base layer 310 may be made of Si, sapphire, SiC, etc. The energy regulation layer 330 may be made of at least one of SiO2, SiOC, Si3N4, AlN, Pt, Mo, W, HfO2, or other materials.

[0061] Exemplarily, each confining groove 331 also penetrates the surface of the energy regulation layer 330 facing away from the piezoelectric transducer structure layer 350, that is, the confining groove 331 penetrates the entire energy regulation layer 330, so that the sound wave energy enters the confining groove 331 and is concentrated on one side of the piezoelectric transducer structure layer 350, thereby enhancing the sound wave energy concentration effect of the confining groove 331.

[0062] In this example, the confining groove 331 can be formed by etching using a deep silicon etching (Deep RIE) technique. By etching the energy regulation layer 330, confining grooves 331 of different shapes and extending directions can be formed. The embodiment of the etching direction of the confining groove 331 is further described below.

[0063] For ease of description, the length direction of the portion of the acoustic resonator 300 cut out in FIG4 is defined as the X-axis, the width direction of the acoustic resonator 300 is defined as the Y-axis, and the thickness direction of the acoustic resonator 300 is defined as the Z-axis. It is understood that the coordinate system of the acoustic resonator 300 can be flexibly set according to specific practical needs.

[0064] Example 1:

[0065] In this embodiment, the energy regulation layer 330 is etched along one direction to form a confining groove 331. Referring to FIG4 , FIG4 is a three-dimensional structural diagram of the acoustic resonator 300 provided in an embodiment of the present application when the second direction is perpendicular to the first direction. The piezoelectric transducer structure layer 350 includes a piezoelectric material layer 340 and an interdigital transducer structure located on the side of the piezoelectric material layer 340 away from the substrate layer 310; the interdigital transducer structure includes a plurality of first interdigital electrodes 351 and a plurality of second interdigital electrodes 352 that are opposite and cross-arranged along a first direction, and the first direction is parallel to the substrate layer 310; the confining groove 331 extends from one side of the energy regulation layer 330 on the opposite sides in the second direction to the other side, and the second direction is parallel to the substrate layer 310, and the second direction is parallel or perpendicular to the first direction.

[0066] Continuing with FIG4 , the interdigital transducer structure further includes a pair of bus bars 353 disposed opposite each other. A plurality of first interdigital electrodes 351 and a plurality of second interdigital electrodes 352 are connected to the two bus bars 353, respectively. The first interdigital electrodes 351 and the second interdigital electrodes 352 each have two sets of ends, one set of which is connected to the bus bar 353, and the other set of ends is spaced apart from the bus bar 353. Both bus bars 353 extend along the X-axis, while the first interdigital electrodes 351 and the second interdigital electrodes 352 extend along the Y-axis. In other words, the first interdigital electrodes 351 and the second interdigital electrodes 352 are perpendicular to the bus bar 353.

[0067] As can be seen, the first interdigital electrodes 351 and the second interdigital electrodes 352 are arranged crosswise along the X-axis direction, that is, the first direction is the X-axis direction. This arrangement, on the one hand, reflects the acoustic wave energy back and forth in the piezoelectric material layer 340 to form oscillations, realizing the transduction function of the acoustic resonator 300, and on the other hand, makes the first interdigital electrodes 351 and the second interdigital electrodes 352 more compact, reducing the space occupied by the first interdigital electrodes 351 and the second interdigital electrodes 352.

[0068] Since the second direction of extension of the confinement groove 331 is related to the first direction, it should be noted that when the confinement groove 331 is formed on the energy regulation layer 330 along the second direction, the energy regulation layer 330 can be etched using silicon deep etching (DeepRIE) technology by referring to the second direction and the first direction. It can be known that the second direction is the etching direction of the confinement groove 331.

[0069] Exemplarily, when the second direction is perpendicular to the first direction, refer to Figures 4 and 5. Figure 4 is a three-dimensional structural diagram of the acoustic resonator 300 provided in an embodiment of the present application. It can be understood that Figure 4 is a three-dimensional structural diagram of the acoustic resonator 300 when the first direction is perpendicular to the first direction, and Figure 5 is a cross-sectional schematic diagram of the acoustic resonator 300 provided in this embodiment in the XZ direction. It can be seen from Figures 4 and 5 that the extension direction of the binding groove 331 is perpendicular to the direction in which the first interdigitated electrode 351 and the second interdigitated electrode 352 are arranged at intervals.

[0070] For example, when the second direction is parallel to the first direction, refer to Figures 6 and 7. Figure 6 is a three-dimensional structural diagram of the acoustic resonator 300 provided in an embodiment of the present application when the first direction is parallel to the second direction, and Figure 7 is a cross-sectional schematic diagram of the acoustic resonator 300 provided in this embodiment in the XZ direction. It can be seen from Figures 6 and 7 that the extension direction of the binding groove 331 is parallel to the direction in which the first interdigitated electrode 351 and the second interdigitated electrode 352 are arranged at intervals.

[0071] However, regardless of whether the second direction is perpendicular or parallel to the first direction, the cross-sectional shape of the energy regulation layer 330 in the XY direction satisfies the following conditions. For example, referring to FIG8 , FIG8 is a schematic cross-sectional view of the confining groove 331 provided in this embodiment, in which the cross-sectional shape in the XY direction is a straight strip. It can be understood that the extension direction of each confining groove 331 is parallel to the second direction or the acute angle can be less than 60°. In this embodiment, the extension direction of the confining groove 331 forms an acute angle with the second direction and the angle can be less than 60°, and the confining grooves 331 are arranged side by side and spaced apart in a direction perpendicular to the second direction, so that when etching the energy regulation layer 330, etching is completed directly along the second direction, shortening the time for etching the energy regulation layer 330 to form the confining grooves 331.

[0072] For example, referring to Figure 9, FIG9 is a schematic cross-sectional view of a confining groove 331 provided in this embodiment, showing a wavy cross-section in the XY direction. It is understood that the confining grooves 331 can be wavy, with the end-to-end line extending along the second direction, and spaced side by side in a direction perpendicular to the second direction. The acoustic resonator 300 utilizes wavy confining grooves 331 to increase the space occupied by the confining grooves 331 on the energy regulation layer 330, thereby increasing the space available for the confining grooves 331 to concentrate acoustic wave energy on the piezoelectric material layer 340, thereby enhancing the confining grooves 331's ability to concentrate acoustic wave energy.

[0073] In this embodiment, referring to Figures 8 and 9 , the energy regulation layer 330 may further include partitions 332 that divide the energy regulation layer 330 into a plurality of confinement grooves 331. The partitions 332 are spaced apart along the second direction. The cross-sectional shape of the partitions 332 in a direction parallel to the base layer 310 may include any of parallel strips, oblique strips, and wavy strips.

[0074] The spacer 332 can occupy a range of 1% to 99% of the area of ​​the energy regulation layer 330. The duty ratio of the spacer 332 includes the cross-sectional area of ​​the spacer 332 parallel to the substrate 310 within one array period / the total area of ​​the spacer 332 and the confining groove 331 within one array period. Here, one array period can be selected based on actual needs. As shown in Figures 8 and 9, 8 columns of spacers 332 are selected as one array period. Within the 8-column array period, the duty ratio of the spacer 332 ranges from 1% to 99%. It is worth noting that the area of ​​the energy regulation layer 330 occupied by the confining groove 331 is larger than the area of ​​the energy regulation layer 330 occupied by the spacer 332, which helps to improve the electromechanical coupling coefficient of the acoustic resonator 300.

[0075] It can be seen that after the confining groove 331 concentrates the acoustic wave energy on the piezoelectric material layer 340, the piezoelectric effect of the piezoelectric material layer 340 can be used to convert electrical energy into acoustic energy, so that the piezoelectric material layer 340 reflects the acoustic wave energy, so that the acoustic wave energy forms a standing wave oscillation between the base layer 310 and the piezoelectric material layer 340, which can reduce the acoustic wave loss of the acoustic resonator 300.

[0076] In order to meet different electromechanical coupling coefficients, different materials can be selected as the piezoelectric material layer 340, and different materials with different Euler angles can also be selected as the piezoelectric material layer 340. For example, the materials of the piezoelectric material layer 340 are shown in Table 1:

[0077] Table 1

[0078] It should be noted that different piezoelectric material layers 340 have different anisotropic properties, and that different piezoelectric material layers 340 of the same material also have different anisotropic properties in the Euler angle direction. Therefore, to suppress the transverse modes of the acoustic resonator 300, the piezoelectric material layer 340 is designed based on the material's anisotropic properties in the horizontal direction.

[0079] For example, the interdigital transducer structure may also use a single-layer electrode, that is, a single layer of metal, or an electrode layer formed by a stacking combination of different metals.

[0080] In order to obtain a larger electromechanical coupling coefficient in this embodiment, the materials of the first interdigital electrodes 351 and the second interdigital electrodes 352 are as shown in Table 2:

[0081] Table 2

[0082] For the acoustic resonator 300 in which the first interdigital electrodes 351 and the second interdigital electrodes 352 are cross-arranged, the above electrode materials are used as the materials for the first interdigital electrodes 351 and the second interdigital electrodes 352, which have the characteristic of large acoustic impedance and facilitate obtaining a large electromechanical coupling coefficient.

[0083] In this embodiment, the acoustic resonator 300 further includes a Bragg reflector layer 320. Referring to FIG4 , FIG4 is a three-dimensional structural diagram of the acoustic resonator 300 provided in an embodiment of the present application. As can be seen from FIG4 , the Bragg reflector layer 320 is located between the base layer 310 and the energy regulation layer 330. It should be noted that the Bragg reflector layer 320 can be composed of alternating high acoustic impedance materials and low acoustic impedance materials. It can be understood that in the Z direction, the Bragg reflector layer 320 can be composed of multiple layers of alternating high acoustic impedance materials and low acoustic impedance materials. In this embodiment, the Bragg reflector layer 320 alternately constitutes three layers.

[0084] It is worth noting that the Bragg reflector 320 can reflect the acoustic wave energy back into the piezoelectric material layer 340, thereby concentrating the acoustic wave energy in the piezoelectric material layer 340. The Bragg reflector 320 includes a high acoustic velocity layer 321 and a low acoustic velocity layer 322. As shown in FIG4 , the high acoustic velocity layers 321 and the low acoustic velocity layers 322 are alternately stacked to form three layers, wherein the high acoustic velocity layer 321, which is farther away from the base layer 310, is closer to the energy regulation layer 330.

[0085] The high acoustic velocity layer 321 is a high acoustic impedance layer, typically made of a material with a high dielectric constant. The low acoustic velocity layer 322 is a low acoustic impedance layer, typically made of a material with a low dielectric constant. The high acoustic velocity layer 321 and the low acoustic velocity layer 322 are overlapped to improve device performance.

[0086] This embodiment provides a material matching table for the high acoustic impedance layer and the low acoustic impedance layer, see Table 3:

[0087] Table 3

[0088] In addition, both the high acoustic impedance layer and the low acoustic impedance layer can be used to control the resonant frequency and amplitude of the device to meet different application requirements.

[0089] Example 2:

[0090] The difference between this embodiment and the first embodiment is that there is no Bragg reflection layer 320 between the base layer 310 and the energy regulation layer 330 .

[0091] For example, as shown in Figure 10, Figure 10 is a three-dimensional structural diagram of the acoustic resonator 300 provided in this embodiment, in which the second direction is perpendicular to the first direction without the Bragg reflector 320. As shown in Figure 10, the extension direction of the confining groove 331, that is, the second direction, is perpendicular to the first direction.

[0092] For example, as shown in FIG11 , FIG11 is a three-dimensional structural diagram of the acoustic resonator 300 provided in this embodiment, in the absence of the Bragg reflector 320 , in which the second direction is parallel to the first direction. It is understood that the extending direction of the confining groove 331 in FIG11 , i.e., the second direction, is parallel to the first direction.

[0093] In both of the above examples, the Bragg reflection layer 320 is omitted, and the confining groove 331 is etched in two ways: in a second direction parallel to or perpendicular to the first direction. The purpose is to reduce the processing difficulty of the acoustic resonator 300, thereby increasing the gap on one side of the piezoelectric material layer 340 through the energy regulation layer 330, and improving the power capacity of the acoustic resonator 300 with a smaller electromechanical coupling coefficient loss.

[0094] Example 3:

[0095] The difference between this embodiment and the first embodiment is that the energy regulation layer 330 is etched along two directions to form the confining grooves 331 .

[0096] For example, as shown in Figure 12, a three-dimensional structure diagram of the acoustic resonator 300 provided in this embodiment, wherein confining grooves 331 are etched in the second and third directions. A portion of the confining grooves 331 extends along the second direction, while another portion extends along the third direction. The second and third directions are non-parallel, facilitating machining along two different directions on the energy regulation layer 330. This increases the selectivity of the etching direction of the confining grooves 331, facilitates adjustment of the machining direction of the energy regulation layer 330, and improves the ease of machining the confining grooves 331.

[0097] For example, as shown in Figure 13, Figure 13 is a schematic cross-sectional view of the confinement grooves 331 provided in this embodiment, with the second and third directions perpendicular. The multiple confinement grooves 331 may include multiple first grooves and multiple second grooves. The first grooves extend from one side of the energy regulation layer 330 in the second direction to the other side; the second grooves extend from one side of the energy regulation layer 330 in the third direction to the other side, with the third direction not being parallel to the second direction. In Figure 13, the third direction is perpendicular to the second direction, which is parallel or perpendicular to the first direction. Furthermore, the third direction may also be parallel or perpendicular to the first direction. This arrangement allows the multiple first grooves and multiple second grooves to intersect and be spaced apart, increasing the distribution of the confinement grooves 331 on the energy regulation layer 330. This increases the proportion of the confinement grooves 331 on the energy regulation layer 330, helping to enhance the concentrating effect of the confinement grooves 331 on the acoustic wave energy.

[0098] It can be further known that since the energy regulation layer 330 is etched along the second direction and the third direction to form the confining grooves 331, a partition 332 is formed between the plurality of first grooves and the plurality of second grooves. The cross-sectional shape of the partition 332 in the direction parallel to the base layer 310 may include any one of a circle, an ellipse, a parallelogram, a rhombus, a square, a rectangle, and a polygon. As shown in FIG13 , the cross-sectional shape of the partition in the direction parallel to the base layer 310 is a rectangle. As shown in FIG14 , FIG14 is a cross-sectional schematic diagram of the partition 332 provided in this embodiment, in which the cross-sectional shape on the XY plane is a circle, and the cross-sectional shape of the partition 332 in the direction parallel to the base layer 310 is a circle.

[0099] In this embodiment, the spacer 332 occupies an area of ​​the energy regulation layer 330 ranging from 1% to 99%. The duty ratio of the spacer 332 comprises the cross-sectional area of ​​the spacer 332 parallel to the substrate 310 within one array period / the total area of ​​the spacer 332 and the confinement groove 331 within one array period. Here, one array period can be determined based on actual needs. For example, as shown in Figures 13 and 14 , 4 rows and 6 columns of spacers 332 are selected as one array period. Within this 4-row, 6-column array period, the duty ratio of the spacer 332 also ranges from 1% to 99%. It is worth noting that the area of ​​the energy regulation layer 330 occupied by the confinement groove 331 can be larger than the area of ​​the energy regulation layer 330 occupied by the spacer 332, which helps to improve the electromechanical coupling coefficient of the acoustic resonator 300.

[0100] In summary, this embodiment adjusts the electromechanical coupling coefficient of the acoustic resonator 300 by adding the energy regulation layer 330 and adjusting the arrangement number and arrangement gap of the confinement grooves 331, thereby improving the power capacity of the transversely excited bulk acoustic wave resonator, achieving a balance between the electromechanical coupling coefficient and the power capacity, and thus improving the quality factor Q of the acoustic resonator 300.

[0101] Therefore, this embodiment further provides a graph to illustrate the design effect of the acoustic resonator 300 .

[0102] Refer to Figure 15, which is a graph showing the relationship between the frequency and the quality factor Q of the acoustic resonator 300 provided in this embodiment. In Figure 15, the horizontal axis is the frequency and the vertical axis is the Y amplitude value. The three curves in the figure are all quality factors Q. For the convenience of comparison, the three curves in the figure are moved 50dB on the vertical axis respectively, so that they can be compared after observation, and the three curves are named Q1, Q2 and Q3 respectively. Q1 is a 4-layer energy regulation layer 330, Q2 is a 1-layer energy regulation layer 330, and Q3 is a solid-assembly type transversely excited bulk acoustic wave resonator. As can be seen from Figure 15, the greater the impedance ratio of the resonance point / anti-resonance point admittance curve, the higher the quality factor Q. This is intuitively reflected in the fact that the sharper the admittance curves at these two points, the higher the quality factor Q, and Q1>Q2>Q3.

[0103] Referring to Figure 16 , Figure 16 shows a graph of the electromechanical coupling coefficient of the acoustic resonator 300 provided in this embodiment when etched along the X and Y directions. In Figure 16 , the abscissa represents the duty cycle of the confining grooves 331, and the ordinate represents the electromechanical coupling coefficient. Because this embodiment allows the energy regulation layer 330 to be etched in both the X and Y directions, the electromechanical coupling coefficients corresponding to the confining grooves 331 after the two etching methods are compared with those of a solid-mounted lateral excitation bulk acoustic wave resonator. As shown in Figure 16 , the electromechanical coupling coefficients obtained when the energy regulation layer 330 is etched along either the X or Y direction are both higher than those of the solid-mounted lateral excitation bulk acoustic wave resonator. Furthermore, corresponding to the multi-layer Bragg reflector 320, this embodiment can improve the power capacity of the acoustic resonator 300 by using a single energy regulation layer 330 at the expense of a smaller loss in the electromechanical coupling coefficient, thus achieving a balanced balance between the electromechanical coupling coefficient and power capacity characteristics of the acoustic resonator 300.

[0104] Referring to FIG17 , FIG17 is a graph showing the slowness curve of the acoustic resonator 300 provided in this embodiment in the XY directions. The solid line in FIG17 represents the slowness curve of the solid-assembly transversely excited bulk acoustic wave resonator, and the dashed lines represent the slowness curves of the acoustic resonator 300 with different numbers of energy regulation layers 330 added. FIG17 shows that the slowness curve of the acoustic resonator 300 with the addition of the energy regulation layer 330 is flatter, and the more layers of energy regulation layer 330 there are, the flatter the slowness curve of the acoustic resonator 300 is. In this way, the slowness curve of the main vibration mode of the acoustic resonator 300 can be controlled by adjusting the number and gap of the acoustic impedance portions. When the slowness curve of the main vibration mode becomes flat, the transverse mode can be suppressed, thereby improving the quality factor Q of the acoustic resonator 300.

[0105] Referring to Figure 18 , Figure 18 is a comparison chart of the dispersion curves of the acoustic resonator 300 provided in this embodiment. The solid line in Figure 18 represents the dispersion curve of a solid-assembly transversely excited bulk acoustic wave resonator, while the dashed lines represent the dispersion curves of the acoustic resonator 300 with different numbers of energy regulation layers 330. Figure 18 shows that the dispersion curve of the acoustic resonator 300 with the addition of the energy regulation layer 330 is flatter. Furthermore, the greater the number of energy regulation layers 330, the flatter the slowness curve of the acoustic resonator 300, and thus the more pronounced the transverse mode suppression of the acoustic resonator 300.

[0106] The embodiment of the present application further provides a method for preparing an acoustic resonator 300 . Referring to FIG. 19 , FIG. 19 is a flow chart of the method for preparing the acoustic resonator 300 provided in the embodiment. The method includes steps S1 to S2 .

[0107] S1. Provide a base layer 310 , and form a piezoelectric transducer structure layer 350 on one side of the base layer 310 .

[0108] S2. An energy regulation layer 330 is formed between the base layer 310 and the piezoelectric transducing structure layer 350 . The energy regulation layer 330 includes a plurality of confining grooves 331 . Each confining groove 331 at least penetrates the surface of the energy regulation layer 330 facing the piezoelectric transducing structure layer 350 .

[0109] In this embodiment, the energy regulation layer 330 is etched along the second direction and / or the third direction to form side-by-side spaced binding grooves 331 or mutually intersecting binding grooves 331, so that a structure in which a partition 332 and a binding groove 331 overlap is formed between the base layer 310 and the piezoelectric material layer 340, so that the piezoelectric material layer 340 can be supported by the partition 332 while the binding groove 331 is used to concentrate the sound wave energy on the piezoelectric material layer 340, thereby improving the electromechanical coupling coefficient of the acoustic resonator 300.

[0110] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An acoustic resonator, characterized in that, Comprising: Substrate layer; Piezoelectric transducer structure layer, disposed on one side of the substrate layer; Energy adjustment layer, disposed between the substrate layer and the piezoelectric transducer structure layer, the energy adjustment layer includes a plurality of confinement grooves, and each of the confinement grooves at least penetrates the surface of the energy adjustment layer facing the piezoelectric transducer structure layer.

2. The acoustic resonator according to claim 1, wherein, Each of the confinement grooves also penetrates the surface of the energy adjustment layer facing away from the piezoelectric transducer structure layer.

3. The acoustic resonator according to claim 1 or 2, characterized in that The piezoelectric transducer structure layer includes a piezoelectric material layer and an interdigital transducer structure located on the side of the piezoelectric material layer away from the substrate layer; the interdigital transducer structure includes a plurality of first interdigital electrodes and a plurality of second interdigital electrodes that are opposite and cross each other in a first direction, and the first direction is parallel to the substrate layer; The confinement grooves extend from one side to the other side of the energy adjustment layer on opposite sides in a second direction, the second direction is parallel to the substrate layer, and the second direction is parallel or perpendicular to the first direction.

4. The acoustic resonator according to claim 3, wherein The extending direction of each of the confinement grooves is parallel to the second direction or the acute angle is less than 60°.

5. The acoustic resonator according to claim 4, wherein, The confinement grooves are wavy and the connection line of the head and tail extends in the second direction.

6. The acoustic resonator according to claim 4, characterized in that, A part of the confinement grooves extends in the second direction, and another part of the confinement grooves extends in a third direction, and the second direction is not parallel to the third direction.

7. The acoustic resonator according to claim 4, characterized in that, The plurality of confinement grooves include a plurality of first grooves and a plurality of second grooves, the first grooves extend from one side to the other side of the energy adjustment layer on opposite sides in the second direction; the second grooves extend from one side to the other side of the energy adjustment layer on opposite sides in the third direction, and the third direction is not parallel to the second direction.

8. The acoustic resonator according to any one of claims 1-7, characterized in that, It further includes a Bragg reflection layer, and the Bragg reflection layer is located between the substrate layer and the energy adjustment layer.

9. The acoustic resonator according to any one of claims 1-8, characterized in that, The energy adjustment layer further includes a partition portion, the partition portion divides the energy adjustment layer into a plurality of the confinement grooves, and the range of the area of the partition portion in the energy adjustment layer is 1% to 99%.

10. The acoustic resonator according to any one of claims 1-9, characterized in that, The material of the energy adjustment layer includes at least one of SiO2, SiOC, Si3N4, AlN, Pt, Mo, W, and HfO2.

11. A method for preparing an acoustic resonator, characterized in that, Comprising: Providing a substrate layer, and forming a piezoelectric transducer structure layer on one side of the substrate layer; Forming an energy adjustment layer between the substrate layer and the piezoelectric transducer structure layer, the energy adjustment layer includes a plurality of confinement grooves, and each of the confinement grooves at least penetrates the surface of the energy adjustment layer facing the piezoelectric transducer structure layer.

12. A filter, characterized in that, Including a plurality of cascaded resonators, and the resonator is an acoustic resonator according to any one of claims 1-10.

13. An electronic device, characterized in that, Including a filter and a circuit board, the filter is disposed on the circuit board, and the filter is a filter according to claim 12.

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