Resonator, method of manufacturing the same, filter, electronic device

Abstract

A resonator, a preparation method thereof, a filter and an electronic device, the resonator comprising a substrate (3), a Bragg reflection layer (2) and a piezoelectric layer (1) which are sequentially stacked; the surface of the piezoelectric layer (1) facing the Bragg reflection layer (2) is provided with a first electrode (11), and the surface of the piezoelectric layer (1) facing away from the Bragg reflection layer (2) is provided with a second electrode (12); the surface of the second electrode (12) facing away from the piezoelectric layer (1) is provided with a boundary ring (13), the resonator has a first resonant region (A1) and a second resonant region (A2) corresponding to the boundary ring (13); along the stacking direction, the Bragg reflection layer (2) comprises a low acoustic resistance structure (21) and a first high acoustic resistance structure (22) embedded in the low acoustic resistance structure (21); the first high acoustic resistance structure (22) is provided with a discontinuous structure (D, F) corresponding to the second resonant region (A2). By reasonably designing the first high acoustic resistance structure (22), the influence of the boundary mode harmonics generated by the boundary ring (13) can be weakened, and the high quality factor of the resonator is maintained; in addition, the manufacturing process of the first high acoustic resistance structure (22) is highly feasible.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filters, and particularly relates to a resonator, a preparation method thereof, a filter and an electronic device. BACKGROUND

[0002] The resonator is widely applied to radio frequency filters of electronic devices such as mobile phones due to its advantages of high performance, small size and strong power tolerance. With the development of 5G technology, the demand for filters is increasing.

[0003] At present, a border ring is arranged on the resonator to improve the quality factor (Q), and the border ring will introduce a border mode or frame mode harmonic in the waveform of the filter. The border mode harmonic will greatly affect the performance of the filter, and this problem needs to be solved urgently. SUMMARY

[0004] The present application provides a resonator, a preparation method thereof, a filter and an electronic device to reduce the influence of the border ring on the filter channel.

[0005] In a first aspect, the application provides a resonator, which comprises a substrate, a Bragg reflector and a piezoelectric layer arranged in sequence; the piezoelectric layer is provided with a first electrode on a surface facing the Bragg reflector and a second electrode on a surface facing away from the Bragg reflector; the second electrode is provided with a boundary ring on a surface facing away from the piezoelectric layer; the presence of the boundary ring changes the resonant frequency distribution of acoustic waves in the resonator, so that the effective resonant region of the entire resonator includes a first resonant region and a second resonant region; the first resonant region is the resonant region of the part of the resonator not provided with the boundary ring, and the second resonant region is the resonant region corresponding to the boundary ring; the boundary ring can relatively improve the quality factor of the entire resonator; along the stacking direction, the Bragg reflector comprises a low acoustic resistance structure and a first high acoustic resistance structure embedded in the low acoustic resistance structure, wherein the first high acoustic resistance structure is provided with a discontinuous structure corresponding to the second resonant region; the discontinuous structure is used to suppress the boundary mode harmonic. The stacking direction should be understood as the direction of sequentially passing through the layer stack, which can be understood as the axial direction, for example, the direction of passing through the entire resonator from the bottom of the substrate to the top of the piezoelectric layer; the first high acoustic resistance structure is a plate-like structure, and the ratio of the radial dimension to the circumferential dimension is relatively large; the first high acoustic resistance structure is embedded in the low acoustic resistance structure, that is, the first high acoustic resistance structure is covered by the low acoustic resistance structure in the stacking direction (equivalent to the axial direction), and is surrounded by the low acoustic resistance structure in the radial direction; the low acoustic resistance structure and the first high acoustic resistance structure are equivalent to being arranged alternately along the stacking direction and are used to reflect acoustic waves. In addition, the first high acoustic resistance layer has a discontinuous structure, so that the thickness of each part of the first high acoustic resistance structure is different, thereby affecting the propagation of acoustic waves, and reasonable design of the first high acoustic resistance structure can change the reflection state of acoustic waves in the Bragg reflector.

[0006] In the above resonator, the first high acoustic resistance structure provided with the discontinuous structure can change the reflection state of acoustic waves in the Bragg reflector, and through reasonable structural design of the first high acoustic resistance structure, the boundary mode harmonic caused by the boundary ring can be suppressed, and the quality factor of the resonator can be maintained; and the process for preparing the first high acoustic resistance structure provided with the discontinuous structure is low in complexity and strong in process implementation feasibility.

[0007] In a possible implementation manner, the discontinuous structure provided on the first high acoustic resistance structure overlaps with the second resonant region and does not overlap with the first resonant region, that is, the discontinuous structure corresponds to the boundary ring structure.

[0008] Among them, a specific implementation method of the first high acoustic impedance structure with such a discontinuous structure can be to provide a groove on the surface of the first high acoustic impedance structure, the groove being provided on the surface of the first high acoustic impedance structure, the surface being the surface of the first high acoustic impedance structure facing the piezoelectric layer, or the surface of the first high acoustic impedance structure facing the substrate, the groove being provided only on either surface of the first high acoustic impedance structure, or being provided on both surfaces of the first high acoustic impedance structure; a specific implementation method of the first high acoustic impedance structure with a discontinuous structure can also be to provide a step on the edge of the first high acoustic impedance structure, along a plane perpendicular to the stacking direction, the bottom surface of the step can face the piezoelectric layer, or the bottom surface of the step can face the substrate. Specifically, when the bottom surface of the step faces the piezoelectric layer or the bottom surface of the step faces the substrate, in a plane perpendicular to the edge, the lateral dimension of the step is greater than 200 nm and less than the distance between the edge and the edge of the first resonant region, and the longitudinal dimension of the step is greater than 20 nm and less than the thickness of the first high acoustic impedance structure. The lateral dimension should be understood as the dimension along the radial direction, and the longitudinal dimension should be understood as the dimension along the stacking direction.

[0009] Among them, the material of the low acoustic resistance structure may include dielectric materials such as SiO2 (silicon dioxide) or SiN (silicon nitride), and the material of the first high acoustic resistance structure may include metal materials such as W (tungsten), Mo (molybdenum), Ru (ruthenium), or dielectric materials such as AlN (aluminum nitride) and Ta2O5 (tantalum pentoxide).

[0010] In one possible implementation, two edges of the first high acoustic impedance structure located in the same plane perpendicular to the stacking direction are respectively provided with steps; in the plane perpendicular to each edge, the lateral dimensions of each step are different, and the longitudinal dimensions of each step are the same.

[0011] It should be understood that the Bragg reflector layer in the present application may also include a second high acoustic impedance structure embedded in the low acoustic impedance structure. The second high acoustic impedance structure is similar to the first high acoustic impedance structure, and along the stacking direction, the second high acoustic impedance structure is parallel to the first high acoustic impedance structure, so that the second high acoustic impedance structure and the first high acoustic impedance structure are equivalent to being provided with a low acoustic impedance structure. Of course, other third high acoustic impedance structures, fourth high acoustic impedance structures, etc. may also be included. All high acoustic impedance structures are distributed in parallel in the direction from the piezoelectric layer to the substrate, and their dimensions perpendicular to the stacking direction gradually increase from the direction from the piezoelectric layer to the substrate.

[0012] When the Bragg reflector in the present application includes at least two high acoustic impedance structures (for example, including a first high acoustic impedance structure and a second high acoustic impedance structure, or including a first high acoustic impedance structure, a second high acoustic impedance structure, a third high acoustic impedance structure, or including a first high acoustic impedance structure, a second high acoustic impedance structure, a third high acoustic impedance structure, and so on), the structure of the resonator provided by the present application can also be described in an inductive summary manner as follows: the present application provides a resonator including: a substrate, a Bragg reflector and a piezoelectric layer arranged in sequence; wherein the piezoelectric layer forms a first electrode towards the surface of the Bragg reflector, the piezoelectric layer forms a second electrode away from the surface of the Bragg reflector, and the second electrode is provided with a boundary ring away from the surface of the piezoelectric layer; the resonator has a first resonant region and a second resonant region corresponding to the boundary ring; along the stacking direction, the Bragg reflector includes a low acoustic impedance structure and N high acoustic impedance structures embedded in the low acoustic impedance structure, where N is an integer greater than or equal to 1; the N high acoustic impedance structures are all plate-shaped structures, the ratio of the radial dimension of each high acoustic impedance structure to the circumferential dimension is relatively large, and the N high acoustic impedance structures are parallel to each other along the stacking direction; the N high acoustic impedance structures are embedded in the low acoustic impedance structure, that is, each high acoustic impedance structure is covered by the low acoustic impedance structure in the stacking direction (equivalent to the axial direction) and surrounded by the low acoustic impedance structure in the radial direction; the low acoustic impedance structure and the N high acoustic impedance structures correspond to the alternating arrangement along the stacking direction for reflecting acoustic waves; wherein at least one high acoustic impedance structure is provided with a discontinuity structure corresponding to the second resonant region.

[0013] In a second aspect, based on the structure of the resonator described above, the present application further provides a preparation method of a resonator for preparing the resonator described above, which has a first resonant region and a second resonant region, and the preparation method specifically includes the following steps:

[0014] providing a substrate;

[0015] providing a Bragg reflector on the substrate; along the stacking direction, the Bragg reflector includes a low acoustic impedance structure and a first high acoustic impedance structure embedded in the low acoustic impedance structure; the first high acoustic impedance structure is provided with a discontinuity structure corresponding to the second resonant region;

[0016] providing a piezoelectric layer on the surface of the Bragg reflector, the piezoelectric layer has a first electrode towards the surface of the Bragg reflector, and the piezoelectric layer has a second electrode away from the surface of the Bragg reflector;

[0017] providing a boundary ring on the surface of the second electrode away from the piezoelectric layer. The fabrication of the boundary ring changes the size of the entire resonator in the stacking direction, so that the resonator has a first resonant region and a second resonant region corresponding to the boundary ring, and the first resonant region and the second resonant region together constitute the effective resonant region of the resonator.

[0018] According to different implementation manners of the discontinuous structure on the first high acoustic impedance structure, the Bragg reflection layer can be arranged on the substrate in different ways.

[0019] The first implementation manner of arranging the Bragg reflection layer on the substrate can include the following steps:

[0020] depositing a low acoustic impedance material on the substrate to form a first low acoustic impedance layer;

[0021] depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer to form a first high acoustic impedance structure;

[0022] patterning the first high acoustic impedance structure; that is, arranging a discontinuous structure such as a groove or a step on the surface of the high acoustic impedance structure.

[0023] depositing a low acoustic impedance material on the surface of the high acoustic impedance structure to form a second low acoustic impedance layer covering the first low acoustic impedance layer;

[0024] planarizing the second low acoustic impedance layer so that the surface of the second low acoustic impedance layer is flush with the first high acoustic impedance structure; here, a chemical mechanical polishing process can be used.

[0025] depositing a low acoustic impedance material on the surface of the second low acoustic impedance layer and the first high acoustic impedance structure to form a third low acoustic impedance layer; at this time, the third low acoustic impedance layer, the second low acoustic impedance layer, and the first low acoustic impedance layer have an integrated structure to form the low acoustic impedance structure.

[0026] The second implementation manner of arranging the Bragg reflection layer on the substrate can include the following steps:

[0027] depositing a low acoustic impedance material on the substrate to form a first low acoustic impedance layer;

[0028] depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer to form a first high acoustic impedance layer;

[0029] depositing a low acoustic impedance material around the first high acoustic impedance layer so that the surface of the first low acoustic impedance layer is flush with the surface of the first high acoustic impedance layer;

[0030] depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer and the first high acoustic impedance layer to form a second high acoustic impedance layer; the second high acoustic impedance layer and the first high acoustic impedance layer have an integrated structure to form the first high acoustic impedance structure; the structural difference between the second high acoustic impedance layer and the first high acoustic impedance layer can constitute the discontinuous structure.

[0031] depositing a low acoustic impedance material on the surface of the second high acoustic impedance layer to form a second low acoustic impedance layer covering the second high acoustic impedance layer;

[0032] planarizing the second low acoustic impedance layer so that the surface of the second low acoustic impedance layer is flush with the surface of the second high acoustic impedance layer; here, a chemical mechanical polishing process can be used.

[0033] A low acoustic impedance material is deposited on the surface of the second low acoustic impedance layer and the second high acoustic impedance layer to form a third low acoustic impedance layer; the first low acoustic impedance layer, the second low acoustic impedance layer and the third low acoustic impedance layer have an integrated structure, and together form a low acoustic impedance structure.

[0034] It should be understood that the preparation method of the resonator herein is for preparing a resonator with only a first high acoustic impedance structure, and when the resonator also has a second high acoustic impedance structure or even more high acoustic impedance structures, the above preparation method will be adjusted accordingly, but the basic steps remain the same, which will not be repeated here.

[0035] In a third aspect, based on the structure of the resonator described above, the application also provides a ladder-type filter, which specifically includes an input terminal, an output terminal, a series branch, a first parallel branch and a first filter unit; one end of the series branch is connected to the input terminal, and the other end is connected to the output terminal; one end of the first parallel branch is connected to the series branch, and the other end is grounded; the first filter unit includes a first series resonator arranged on the series branch and a first parallel resonator arranged on the first parallel branch; wherein the first series resonator is provided with a structure for suppressing a boundary mode harmonic.

[0036] In a possible implementation manner, the first series resonator can be the same as the resonator structure provided in the first aspect, that is, the first series resonator includes a substrate, a Bragg reflection layer and a piezoelectric layer arranged in sequence; the piezoelectric layer is provided with a first electrode on the surface facing the Bragg reflection layer, and a second electrode on the surface away from the Bragg reflection layer, the first resonant region and the second resonant region; the second electrode is provided with a boundary ring on the surface away from the piezoelectric layer, so that the first series resonator has a first resonant region and a second resonant region corresponding to the boundary ring; in the stacking direction, the Bragg reflection layer includes a low acoustic impedance structure and a first high acoustic impedance structure embedded in the low acoustic impedance structure; the first high acoustic impedance structure has a discontinuity structure corresponding to the second resonant region, for suppressing a boundary mode harmonic. Since the first series resonator can suppress the boundary mode harmonic, the passband of the filter can be improved. The first parallel resonator herein can also be selected to be the same as the resonator structure provided in the first aspect, which will not be repeated here.

[0037] It can be understood that the filter herein can also include a second parallel branch and a second filter unit, one end of the second parallel branch is connected to the series branch, and the other end is grounded; the second filter unit includes a second series resonator connected to the series branch and a second parallel resonator connected to the second parallel branch; the second series resonator is in series with the first series resonator, and the second parallel resonator is in parallel with the first parallel resonator. Similar to the first filter unit, the second series resonator in the second filter unit can also be selected to be the same as the resonator structure provided in the first aspect, and the second parallel resonator can also be selected to be the same as the resonator structure provided in the first aspect.

[0038] In a fourth aspect, based on the structure of the filter described above, the present application further provides an electronic device, which can include a transceiver, a memory and a processor, wherein the transceiver is provided with the filter described above. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1a A structural diagram of a solid energy resonator in the prior art;

[0040] Figure 1b An impedance waveform diagram of a solid energy resonator in the prior art;

[0041] Figure 1c A passband waveform diagram of a filter in the prior art;

[0042] Figure 2 A top view of a resonator provided by an embodiment of the present application;

[0043] Figure 3a A structural diagram of a Bragg reflection layer in a resonator provided by an embodiment of the present application;

[0044] Figure 3b A structural diagram of a first high acoustic resistance structure in a resonator provided by an embodiment of the present application;

[0045] Figure 3c A sectional structural diagram of a resonator provided by an embodiment of the present application;

[0046] Figure 3d A local structural diagram of a first high acoustic resistance structure in a resonator provided by an embodiment of the present application;

[0047] Figure 3e An impedance waveform simulation diagram of a resonator provided by an embodiment of the present application and a resonator in the prior art;

[0048] Figure 3f A Figure 3e A local enlarged diagram of M1 in FIG. 8;

[0049] Figure 3g A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of impedance waveform simulation diagrams;

[0050] Figure 3h A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of impedance waveform simulation diagrams; Figure 3g A partial enlarged view of M2 in the resonator provided by an embodiment of the present application;

[0051] Figure 3i A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams;

[0052] Figure 3j A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams;

[0053] Figure 3k A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of resonance frequency impedance simulation diagrams;

[0054] Figure 3l A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams;

[0055] Figure 3m A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of resonance frequency impedance simulation diagrams;

[0056] Figure 4a A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams;

[0057] Figures 4b to 4e A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams;

[0058] Figure 5 A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams;

[0059] Figure 6a A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams;

[0060] Figure 6b A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams; Figure 6a A structure diagram of a first high acoustic resistance structure in the resonator provided by an embodiment of the present application;

[0061] Figure 6c A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams; Figure 6d

[0062] A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams; Figure 7

[0063] A resonator provided by an embodiment of the present application and a resonator in the prior art are compared in terms of anti-resonance frequency impedance simulation diagrams;Figure 8 A flowchart of a process of setting a Bragg reflection layer in a preparation method of a resonator provided in an embodiment of the present application is shown in FIG. 1.

[0064] Figures 9a to 9f A schematic diagram of structural changes in a process of a Bragg reflection layer of a resonator provided in preparation of an embodiment of the present application is shown in FIG. 2.

[0065] Figure 10 A flowchart of a process of setting a Bragg reflection layer in a preparation method of a resonator provided in an embodiment of the present application is shown in FIG. 1.

[0066] Figures 11a to 11f A schematic diagram of structural changes in a process of a Bragg reflection layer of a resonator provided in preparation of an embodiment of the present application is shown in FIG. 2.

[0067] Figures 12 to 14 A schematic diagram of a structure of a filter provided in an embodiment of the present application is shown in FIG. 3.

[0068] Figure 15a A schematic diagram of a passband waveform comparison between a filter provided in an embodiment of the present application and a conventional filter is shown in FIG. 4.

[0069] Figure 15b A schematic diagram of a passband waveform comparison between two filters provided in an embodiment of the present application is shown in FIG. 5.

[0070] Figure 16 A schematic diagram of a structure of an electronic device provided in an embodiment of the present application is shown in FIG. 6.

[0071] Figure 17 A schematic diagram of a structure of a terminal device provided in an embodiment of the present application is shown in FIG. 7. DETAILED DESCRIPTION

[0072] Piezoelectric thin film bulk acoustic resonators are widely used in filters of electronic devices such as mobile phones. Currently, the main piezoelectric thin film bulk acoustic resonators include a thin film cavity resonator (FBAR, free-standing bulk acoustic resonator) and a solid-mounted resonator (SMR). Among them, the solid-mounted resonator uses a high-low acoustic resistance structure to form a Bragg reflection layer to reflect acoustic waves and limit energy. For example, the FBAR is a thin film resonator with a thickness of about 1 μm, and the SMR is a solid-mounted resonator with a thickness of about 100 μm. Figure 1aThe structure of the solid energy resonator shown is taken as an example, the solid energy resonator comprises a substrate 1', a Bragg reflection layer 2' (comprising a low acoustic resistance layer 21' and a high acoustic resistance layer 22' in a stack) and a piezoelectric layer 3', wherein the piezoelectric layer 3' is provided with an upper electrode 31' on the side away from the Bragg reflection layer 2' and a lower electrode 32' on the side facing the Bragg reflection layer 2'; in order to improve the quality factor (Q, quality factor) of the resonator and at the same time suppress the transverse harmonic, a boundary ring A is arranged on the upper electrode 31' of the solid energy resonator, so that the resonator has different thicknesses at different positions; specifically, the thickness of the resonator part provided with the boundary ring A is larger, the vibration frequency of the sound propagating in this part of the resonator is lower, and the thickness of the resonator part not provided with the boundary ring A is smaller, the vibration frequency of the sound propagating in this part of the resonator is higher, and such a difference in vibration frequency will cause the resonator to have a different resonant frequency at different positions, as shown in the following figure. Figure 1b As shown, a boundary mode harmonic B composed of one or more resonances is introduced before the resonant waveform a2 of the resonator, wherein a1 is the resonant waveform of the fixed resonator without the boundary ring A (here, the frequency of a1 is shifted by 10 MHz from a2 to obtain a more clear contrast effect); as shown in the waveform of the filter, Figure 1c The introduction of the boundary mode harmonic B will cause fluctuations in the passband of the filter, and even cause the passband of the filter to deteriorate (as shown in position C in the middle). Figure 1c

[0073] Therefore, the embodiment of the present application provides a resonator to reduce the above-mentioned influence.

[0074] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be described in further detail below with reference to the accompanying drawings.

[0075] The terms used in the following embodiments are only for the purpose of describing the specific embodiments and are not intended to be limiting on the present application. As used in the specification and the appended claims of the present application, the singular expressions "one", "a", "said", "the above", "the" and "this" are intended to also include expressions such as "one or more", unless there is clear indication to the contrary in the context.

[0076] ​Reference to "one embodiment" or "some embodiments" or "one implementation" or "some implementations" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" or "in some embodiments" or "in other embodiments" or "in still other embodiments" or other similar phrases in the specification are not necessarily all referring to the same embodiment.

[0077] First, please refer to Figure 2 The resonator provided by the embodiment of the present application, Figure 2 is a top view structural schematic diagram of the resonator, it can be seen that the resonator is shown in a pentagonal structure. Figure 2 The piezoelectric layer 1 and the Bragg reflection layer 2 of the resonator are shown in the figure, of course, the resonator also includes a substrate 3 arranged at the bottom of the Bragg reflection layer 2, generally, the structure of the substrate 3 matches the structure of the Bragg reflection layer 2, therefore, in the perspective of Figure 2 , the substrate 3 is blocked by the Bragg reflection layer 2 here and is not shown, the substrate 3 will be shown in the subsequent figures. Please continue to refer to Figure 2 , the first electrode 11 and the second electrode 12 are arranged on the piezoelectric layer 1, the boundary ring 13 is arranged on the surface of the second electrode 12, it can be seen that the shape of the boundary ring 13 matches the shape of the piezoelectric layer 1, which is a pentagon. It can be understood that, Figure 2 The boundary ring 13 is shown in a continuous and uninterrupted ring structure in the figure, of course, the boundary ring 13 can also have the possibility of discontinuity or interruption, which does not affect the effect realization of the embodiment of the present application, here only takes the boundary ring 13 in Figure 2 as an example for illustrative description.

[0078] The structure of the Bragg reflection layer 2 in it can refer to Figure 3a , the Bragg reflection layer 2 includes a low acoustic resistance structure 21 and a first high acoustic resistance structure 22 embedded in the low acoustic resistance structure 21; the first high acoustic resistance structure 22 is embedded in the low acoustic resistance structure 21, that is, in addition to the low acoustic resistance structure 21 in the stacking direction, the high acoustic resistance structure 22 is also surrounded by the low acoustic resistance structure 21 in the radial direction. It can be seen that the shape of the first high acoustic resistance structure 22 and the low acoustic resistance structure 21 is similar to the whole Bragg reflection layer 2, which is a pentagon in the cross section perpendicular to the Y direction, that is, it matches the structure of the above-mentioned boundary ring 13.

[0079] It should be understood that the low acoustic impedance structure 21 and the high acoustic impedance structure 22 are both aimed at the parameter of acoustic impedance. Impedance refers to the resistance that needs to be overcome to displace the medium. The acoustic impedance here can be defined as "sound pressure / speed of the medium flowing through an area", or can be expressed as "the product of the medium density and the speed of sound". The low acoustic impedance structure 21 refers to a structure formed by a material with low acoustic impedance, and the high acoustic impedance structure 22 is a structure formed by a material with high acoustic impedance. The acoustic impedances of the two are relative. In the embodiment of the present application, the material of the low acoustic impedance structure 21 may include dielectric materials such as SiO2 or SiN, and the material of the high acoustic impedance structure 22 may include metal materials such as W, Mo, Ru, or dielectric materials such as AlN and Ta2O5.

[0080] by Figure 3b As an example, the structure of the resonator shown in FIG. Figure 3b As shown, a step D is provided on a certain edge of the first high acoustic impedance structure 22. The step D is equivalent to a discontinuous structure that makes the surface of the first high acoustic impedance structure 22 discontinuous. When the resonator provided by the embodiment of the present application is cut with a plane perpendicular to the edge with the step D, the following can be obtained: Figure 3c The cross-sectional structure of the resonator shown is shown (it should be understood that Figure 3c The corresponding relationship of each structure of the resonator in the cross-section state is only shown as an example, and does not completely correspond to Figure 2 (structural details in ).

[0081] Please refer to Figure 3c , the resonator includes a certain direction ( Figure 3b A substrate 3, a Bragg reflector 2, and the piezoelectric layer 1 are stacked in sequence (in the Y direction). A first electrode 11 is provided on the surface of the piezoelectric layer 1 facing the Bragg reflector 2, a second electrode 12 is provided on the surface of the piezoelectric layer 1 facing away from the Bragg reflector 2, and a boundary ring 13 is provided on the surface of the second electrode 12 facing away from the piezoelectric layer 1. Here, the second electrode 12 is located on the surface of the resonator, while the first electrode 11 is equivalent to being pressed against the side of the piezoelectric layer 1 facing the Bragg reflector 2.

[0082] Among them, Figure 3c In the figure, the resonator has a first resonance area A1 and a second resonance area A2. The first resonance area A1 and the second resonance area A2 together constitute the effective resonance area of ​​the entire resonator. The area division of the two is the space corresponding to the stacking direction of each layer structure of the resonator; the second resonance area A2 corresponds to the above-mentioned boundary ring 13. It should be understood that the above-mentioned "correspondence" refers to: along the stacking direction, the three-dimensional space formed by the projection range of the boundary ring 13 in the entire resonator. When the boundary ring 13 is a ring structure, the second resonance area A2 should also be a ring structure. Figure 3cIn the illustrated state, the second resonance region A2 is shown as region A21 and region A22. Figure 3c , a step D is provided on the left edge of the first high acoustic resistance structure 22. It should be understood that Figure 3c The viewing angle shown, and along the direction perpendicular to the stacking direction (ie Figure 3c The bottom surface of the step D (the surface parallel to the X direction) faces the piezoelectric layer 1. Taking the edge as a reference, in the plane perpendicular to the edge, the lateral dimension W of the step D (i.e., along the Figure 4b The dimension in the X direction is greater than 200 nm and smaller than the distance E between the edge and the edge of the first resonance region A1, and the longitudinal dimension H of the step D (i.e., the dimension in the X direction) is greater than 200 nm and smaller than the distance E between the edge and the edge of the first resonance region A1. Figure 4b The dimension in the Y direction is greater than 20 nm and less than the thickness of the high acoustic resistance structure 22. Figure 3d The schematic diagram of the partial structure of the first high acoustic impedance structure 22 is shown. A step D is set on one of the edges of the first high acoustic impedance structure 22. Considering the process limitations, the angle α between the side and bottom of the step D can be set to 90±30°.

[0083] Next, Figure 3c The resonator structure shown in the figure is used as an example to simulate the resonator. The lateral dimension W of the step D in the resonator is set to 1 μm, and the longitudinal dimension H of the step D is adjusted from 50 nm to 400 nm. The impedance curve change of the resonator can be referred to Figure 3e As shown, curve G1 is the impedance curve of the resonator in the prior art, and the other curves are, from bottom to top, the impedance curves of the resonator provided in the embodiment of the present application when the lateral dimension W of the step D is 1 μm and the longitudinal dimension H increases from 50 nm to 400 nm. Here, in order to clearly compare the data, the data of adjacent curves are offset by 5 dB in the vertical axis direction; among them, as the longitudinal dimension H of the step D increases, the boundary mode harmonic B shows a trend of gradually weakening; the part M1 of each impedance curve with the boundary mode harmonic B is magnified to obtain Figure 3f It can be seen that compared with the resonator in the prior art, the resonator provided in the embodiment of the present application has a significant suppressive effect on the boundary mode harmonic B; it should be understood that the "suppression" here refers to the reduction of the boundary mode harmonic B, and it is not necessarily necessary to achieve the effect of elimination, as long as the influence of the boundary mode harmonic B on the passband of the filter is reduced.

[0084] Alternatively, the longitudinal dimension H of the step D in the resonator is set to 300 nm, and the lateral dimension W of the step D is adjusted from 0.4 to 2 μm. The impedance curve change of the resonator can be referred to Figure 3g As shown; Figure 3gAs shown, G1 is the impedance curve of the resonator in the prior art, and the other curves from bottom to top are respectively the impedance curves of the resonator provided by the embodiment of the present application when the lateral dimension W of the step D increases from 0.4 to 2 μm and the longitudinal dimension H is 300 nm, and here, in order to clearly compare the data, the data of adjacent curves are offset by 5 dB in the ordinate direction; with the increase of the lateral dimension W of the step D, the boundary mode harmonic B presents a trend of weakening first and then strengthening, and a significant improvement occurs near W = 1 μm; the part M2 of each impedance curve with the boundary mode harmonic B is enlarged to obtain Figure 3h As can be seen, compared with the resonator in the prior art, the resonator provided by the embodiment of the present application has a significant suppression effect on the boundary mode harmonic B.

[0085] In addition, the resonator provided by the embodiment of the present application not only can suppress the boundary mode harmonic B, but also can maintain the high quality factor of the resonator with a boundary ring. The lateral dimension W of the step D in the resonator is set to 400 nm, and the longitudinal dimension H of the step D is adjusted to increase from 50 nm to 400 nm, and please refer to Figure 3i The anti-resonant frequency impedance (Zp, impedance at anti-resonant frequency) of the resonator provided by the embodiment of the present application shown in the example changes with the longitudinal dimension H of the step D, and G2 is the anti-resonant frequency impedance of the resonator in the prior art; as can be seen, with the increase of the longitudinal dimension H of the step D from 50 nm to 400 nm, the anti-resonant frequency impedance presents a slight upward trend, and when H = 400 nm, the anti-resonant frequency impedance decreases obviously.

[0086] In yet another example, the lateral dimension W of the step D in the resonator is set to 0-2 μm, and the longitudinal dimension H of the step D is adjusted to 300 nm, and please refer to Figure 3j The anti-resonant frequency impedance of the resonator provided by the embodiment of the present application shown in the example changes with the lateral dimension W of the step D, and G2 is the anti-resonant frequency impedance value of the resonator in the prior art; as can be seen, with the increase of the lateral dimension W of the step D from 0 to 2 μm, the anti-resonant frequency impedance presents an obvious fluctuation, and except that the anti-resonant frequency impedance decreases obviously near W = 1 μm, the anti-resonant frequency impedance at other positions is basically consistent with that when W = 0.

[0087] In addition, the lateral dimension W of the step D in the resonator is set to 0-2 μm, and the longitudinal dimension H of the step D is adjusted to 300 nm, and please refer to Figure 3kThe resonant frequency impedance (Zs, impedance at resonant frequency) of the resonator provided by the example embodiment of the present application varies with the lateral dimension W of the step D, and G3 is the resonant frequency impedance value of the resonator in the prior art; it can be seen that as the lateral dimension W of the step D increases from 0 to 1 μm, the resonant frequency impedance is obviously lower than the resonant frequency impedance in the prior art.

[0088] In combination Figures 3i to 3k of the example, the resonant frequency impedance and the anti-resonant frequency impedance of the resonator vary with the lateral dimension W and the longitudinal dimension H of the step D, and a batch simulation can obtain Figure 3l the state diagram of the anti-resonant frequency impedance varying with the lateral dimension W and the longitudinal dimension H of the step D, and Figure 3m the state diagram of the resonant frequency impedance varying with the lateral dimension W and the longitudinal dimension H of the step D. Taking Figure 3l as an example, different lateral dimensions W cooperate with different longitudinal dimensions H to correspond to different anti-resonant frequency impedance values, and the mesh surface formed by all the anti-resonant frequency impedance values presents a periodic fluctuation surface, that is, the anti-resonant frequency impedance value fluctuates periodically with the different changes of the lateral dimension W and the longitudinal dimension H of the step D; except for the small part of the anti-resonant frequency impedance values, the anti-resonant frequency impedance at the remaining positions is large, that is, the resonator can maintain a high anti-resonant frequency quality factor (Qp, quality factor at anti-resonant frequency).

[0089] Referring to Figure 3m , different lateral dimensions W cooperate with different longitudinal dimensions H to correspond to different resonant frequency impedance values, and the mesh surface formed by all the resonant frequency impedance values presents a periodic fluctuation surface, and the resonant frequency impedance value fluctuates periodically with the different changes of the lateral dimension W and the longitudinal dimension H of the step D; however, the fluctuation of the resonant frequency impedance is very small relatively, and it can be considered that it has no effect on the resonant frequency quality factor (Qs, quality factor at resonant frequency) of the resonator.

[0090] In combination Figure 3l and Figure 3m , it can be seen that the resonator provided by the example embodiment of the present application can select the corresponding lateral dimension W and longitudinal dimension H of the step D in actual use in order to obtain the best anti-resonant frequency impedance value.

[0091] In a possible implementation manner, as shown in Figure 4a , the Bragg reflection layer 2 can further include a second high acoustic resistance structure 23, and the first high acoustic resistance structure 22 and the second high acoustic resistance structure 23 are arranged in Figure 4aThe first high acoustic resistance structure 22 and the second high acoustic resistance structure 23 are arranged in a parallel manner from top to bottom, and the low acoustic resistance structure 21 is arranged between the first high acoustic resistance structure 22 and the second high acoustic resistance structure 23. In view of the layered structure of the first high acoustic resistance structure 22 and the second high acoustic resistance structure 23, the first high acoustic resistance structure 22 and the second high acoustic resistance structure 23 are parallel along the stacking direction (i.e., the Y direction); and along the opposite direction of the Y direction, the size (equivalent to the radial size) of the first high acoustic resistance structure 22 and the second high acoustic resistance structure 23 perpendicular to the stacking direction gradually increases from top to bottom. In the entire resonator, the smaller the size of the first high acoustic resistance structure 22, the closer it is to the piezoelectric layer 1; and the larger the size of the second high acoustic resistance structure 22, the closer it is to the substrate 3. Such a structural design is considered in view of the fact that the wave shape range of the sound is increasing when the sound propagates from the side of the piezoelectric layer 1 to the side of the substrate 3. The high acoustic resistance structure can be matched with the wave shape of the sound to meet the resonance requirement.

[0092] It can be understood that the Bragg reflection layer 2 can further include a third high acoustic resistance structure, a fourth high acoustic resistance structure, and more high acoustic resistance structures. All the high acoustic resistance structures are embedded in the low acoustic resistance structure and parallel to each other along the stacking direction, and the radial size of each high acoustic resistance structure gradually increases from the direction of the piezoelectric layer 1 to the substrate 3. Of course, the low acoustic resistance structure 21 is arranged between any two high acoustic resistance structures, so that each high acoustic resistance structure and the low acoustic resistance structure are arranged in a layered structure alternately, facilitating the propagation and reflection of the sound in each layer structure.

[0093] In Figure 4a the structure of the resonator shown in the figure, the resonator provided by the embodiment of the present application is cut along a plane perpendicular to the edge having the step D, and the cross-sectional structure of the resonator is obtained as shown in the figure. Figure 4b It should be understood that Figure 4b only the corresponding relationship of each structure of the resonator in the cross-sectional state is exemplarily shown, and does not completely correspond to the structural details in Figure 2 ).

[0094] In Figure 4b , the radial size (size along the X direction) of the first high acoustic resistance structure 22 is smaller than the radial size (size along the X direction) of the second high acoustic resistance structure 23 along the direction from the piezoelectric layer 1 to the substrate 3, wherein the size of the first high acoustic resistance structure 22 can refer to B1, and the size of the second high acoustic resistance structure 23 can refer to B2. Taking the substrate 3 as a reference, the projection area of B1 on the substrate 3 is smaller than the projection area of B2 on the substrate 3.

[0095] In Figure 4b the structure of the resonator shown in the figure, Figure 4c another cross-sectional structure of the resonator is shown. As shown in the figure, Figure 4c the second high acoustic resistance structure 23 is provided with a step D on the edge corresponding to the same side of the step D of the first high acoustic resistance structure 22. Of course, the low acoustic resistance structure 21 is arranged between any two high acoustic resistance structures, so that each high acoustic resistance structure and the low acoustic resistance structure are arranged in a layered structure alternately, facilitating the propagation and reflection of the sound in each layer structure.Figure 4b Similar to the example in , each step D must meet the following requirements: the lateral dimension W of the step D is greater than 200 nm and smaller than the distance between the edge and the edge of the first resonance area A1 , and the longitudinal dimension H of the step D is greater than 20 nm and smaller than the thickness of the high acoustic impedance structure 22 .

[0096] exist Figure 4b Based on the structure of the resonator shown in the example, Figure 4d FIG shows a cross-sectional structure of another resonator. Figure 4d As shown, the two edges of the first high acoustic resistance structure 22 (due to the limitation of the viewing angle, equivalent to Figure 4d As shown in FIG, a step D is provided at each end of the first high acoustic resistance structure 22. Figure 4b Similar to the example in , each step D must meet the following requirements: the lateral dimension W of the step D is greater than 200 nm and smaller than the distance between the edge and the edge of the first resonance area A1 , and the longitudinal dimension H of the step D is greater than 20 nm and smaller than the thickness of the high acoustic resistance structure 22 .

[0097] It is understandable that Figure 4d The two steps D shown in the figure are respectively arranged on two edges of the first high acoustic impedance structure 22. The above steps D can also be respectively arranged on three edges or four edges of the first high acoustic impedance structure 22. When the shape of the Bragg reflector 2 changes, the shape of the first high acoustic impedance structure 22 also changes accordingly. The number of steps D is related to the number of edges of the first high acoustic impedance structure 22. For example, if the Bragg reflector 2 is a heptagon, then the first high acoustic impedance structure 22 will also be a heptagon, and the number of edges on which the steps D can be arranged will become seven.

[0098] Under the condition that the thickness of the first high acoustic resistance structure 22 is ignored, when the number of edges of the step D is set to 2, for example Figure 4d In the resonator structure shown, the lateral dimensions of each step D can be set in a plane perpendicular to each edge, while the longitudinal dimensions of each step D are the same. The longitudinal dimension corresponds to the propagation of the sound wave in the Y direction, while the lateral dimension corresponds to the propagation of the sound wave in the X direction. This structural design is conducive to meeting the resonance requirements. Of course, the number of edges provided with steps D can be increased, for example, 3, 4, 5, or even more, and the specifications and dimensions of each step D should also meet the above conditions.

[0099] exist Figure 4b Based on the structure of the resonator shown in the example, Figure 4e A structural variation of the resonator is shown. Figure 4e As shown, the step D here is also set on a certain edge of the first high acoustic resistance structure 22, Figure 4b The difference from the structure in FIG is that the bottom surface of the step D here faces the substrate 3 .

[0100] In combination Figure 4b The resonator and Figure 4e The resonator, Figure 5 A structure of a resonator is shown, the thickness of the first high acoustic resistance structure 22 is not negligible, along the thickness direction of the first high acoustic resistance structure 22, two edges on the same side of the high acoustic resistance structure 22 are respectively provided with two steps D, one of which is the bottom surface of the step D facing the piezoelectric layer 1, and the other is the bottom surface of the step D facing the substrate 3. It should be understood that the longitudinal dimension H of each step D here is greater than 20nm and less than 1 / 2 of the thickness of the first high acoustic resistance structure 22.

[0101] In addition, Figure 6a A structure of a resonator that can be implemented is also shown, which is different from the structures of the resonators shown in Figure 3c , Figures 4b to 4e and Figure 5 The difference is that a groove F is provided on the surface of the first high acoustic resistance structure 22 facing the piezoelectric layer 1, and the opening of the groove F faces the piezoelectric layer 1. Figure 6a The projection of the groove F on the piezoelectric layer 1 falls within the projection range of the boundary ring 13 on the piezoelectric layer 1. The structure of the groove F relative to the first high acoustic resistance structure 22 can be referred to Figure 6b .

[0102] Of course, the opening of the groove F can also face the substrate 3 (as shown in Figure 6c ), and grooves F can also be provided on both surfaces of the first high acoustic resistance structure 22 (as shown in Figure 6d ), and in addition, the number and shape of the grooves F are not limited here.

[0103] It should be understood that Figures 4b to 4e and Figure 5 and Figures 6a to 6c Only a few structures of resonators that can be implemented are shown, whether it is a discontinuous structure in the form of a step D or a discontinuous structure in the form of a groove F, both of which are structures for suppressing boundary mode harmonics in this application, and two or more of them can be combined to meet the needs of suppressing boundary mode harmonics in the implementation process. In addition, the above steps D and grooves F are all ways of providing discontinuous structures on the surface of the high acoustic resistance structure (for example, the first high acoustic resistance structure 22), and this application does not limit that discontinuous structures can only be provided on the surface of the high acoustic resistance structure. For example, discontinuous structures can also be provided inside the high acoustic resistance structure, which will not be described here.

[0104] Taking the structure of the resonator provided in the above embodiments as an example, the embodiments of the present application can also provide a preparation method of a resonator, taking the structure of the resonator shown in Figure 3c , the resonator here has a first resonant region A1 and a second resonant region A2; in combination with reference toFigure 7 The method for manufacturing the resonator comprises the following steps:

[0105] S1: providing a substrate 3; the substrate 3 can be made of silicon.

[0106] S2: disposing a Bragg reflection layer 2 on the substrate 3; along the stacking direction, the Bragg reflection layer 2 comprises a low acoustic impedance structure 21 and a first high acoustic impedance structure 22 embedded in the low acoustic impedance structure 21; the first high acoustic impedance structure 22 has a discontinuous structure corresponding to the second resonant region A2; the discontinuous structure is used to suppress the boundary mode harmonic;

[0107] S3: disposing a piezoelectric layer 1 on the surface of the Bragg reflection layer 2; the piezoelectric layer 1 has a first electrode 11 on the surface facing the Bragg reflection layer 2, and has a second electrode 12 on the surface facing away from the Bragg reflection layer 2;

[0108] S4: disposing a boundary ring 13 on the surface of the second electrode 12 facing away from the piezoelectric layer 1.

[0109] Referring to Figure 3c , the stacking direction is the Y direction; in Figure 3c , a certain edge of the first high acoustic impedance structure 22 is provided with a step D, and in Figure 6a , the surface of the first high acoustic impedance structure 22 is provided with a groove F, both of which can make the first high acoustic impedance structure 22 have a discontinuous structure facing the surface of the piezoelectric layer 1.

[0110] For different structural implementation forms of the first high acoustic impedance structure 22, the step S2 of disposing the Bragg reflection layer 2 on the substrate 3 can also have different implementation steps, which can be specifically referred to the following examples.

[0111] Method one, as shown in Figure 8 , the step S2 can specifically comprise the following steps:

[0112] S211: depositing a low acoustic impedance material on the substrate 3 to form a first low acoustic impedance layer 211, to obtain a structure as shown in Figure 9a ;

[0113] S212: depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer 211 to form a first high acoustic impedance structure 22, to obtain a structure as shown in Figure 9b ;

[0114] S213: patterning the first high acoustic impedance structure 22 to make the first high acoustic impedance structure 22 have a discontinuous structure (step D), to obtain a structure as shown in Figure 9c ;

[0115] S214: depositing a low acoustic impedance material on the surface of the first high acoustic impedance structure 22 to form a second low acoustic impedance layer 212 covering the first low acoustic impedance layer 211, which can obtain Figure 9d the structure shown in FIG. 2B;

[0116] S215: planarizing the second low acoustic impedance layer 212 to keep the surface of the second low acoustic impedance layer 212 flush with the first high acoustic impedance structure 22, which can obtain Figure 9e the structure shown in FIG. 2C;

[0117] S216: depositing a low acoustic impedance material on the surface of the second low acoustic impedance layer 212 and the first high acoustic impedance structure 22 to form a third low acoustic impedance layer 213. As Figure 9f shown in FIG. 2D, the first low acoustic impedance layer 211, the second low acoustic impedance layer 212 and the third low acoustic impedance layer 213 have an integrated structure, and together form the low acoustic impedance structure 21.

[0118] It can be seen that the bottom surface of the step D on the first high acoustic impedance structure 22 shown in this way is towards the piezoelectric layer 1, which can correspond Figure 3c , Figure 4b , Figure 4c , Figure 4d the structure of the step D shown in FIG. 1B and Figure 6a the structure of the groove F shown in FIG. 1C, and Figure 5 the structure of the step D towards the piezoelectric layer 1 in FIG. 1D and Figure 6d the structure of the groove F towards the piezoelectric layer 1 in FIG. 1E.

[0119] Method two, as Figure 10 shown in FIG. 3, step S2 can specifically include the following steps:

[0120] S221: depositing a low acoustic impedance material on the substrate 3 to form a first low acoustic impedance layer 211, the structure of which can refer to Figure 9a shown in FIG. 2A, which is not shown in the figure here;

[0121] S222: depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer 211 to form a first high acoustic impedance layer 221, which can obtain Figure 9a the structure shown in FIG. 2B; Figure 11a the structure shown in FIG. 2C;

[0122] S223: depositing a low acoustic impedance material around the first high acoustic impedance layer 221 to keep the surface of the first low acoustic impedance layer 211 flush with the surface of the first high acoustic impedance layer 221, which can obtain Figure 11b the structure shown in FIG. 2D;

[0123] S224: depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer 211 and the first high acoustic impedance layer 221 to form a second high acoustic impedance layer 222; here, as Figure 11cAs shown, the second high acoustic resistance layer 222 and the first high acoustic resistance layer 221 have an integrated structure, and the radial dimension of the second high acoustic resistance layer 222 is greater than the radial dimension of the first high acoustic resistance layer 221 to form the first high acoustic resistance structure 22 with a discontinuous structure (step D);

[0124] S225: depositing a low acoustic resistance material on the surface of the second high acoustic resistance layer 222 to form a second low acoustic resistance layer 212 covering the second high acoustic resistance layer 222, and obtaining Figure 11d As shown, the second low acoustic resistance layer 212 and the first low acoustic resistance layer 212 have an integrated structure.

[0125] S226: planarizing the second low acoustic resistance layer 212 to keep the surface of the second low acoustic resistance layer 212 flush with the surface of the second high acoustic resistance layer 222, and obtaining Figure 11e As shown, the structure;

[0126] S227: depositing a low acoustic resistance material on the surface of the second low acoustic resistance layer 212 and the second high acoustic resistance layer 222 to form a third low acoustic resistance layer 213. As Figure 11f shown, the first low acoustic resistance layer 211, the second low acoustic resistance layer 212, and the third low acoustic resistance layer 213 have an integrated structure, and together form the low acoustic resistance structure 21.

[0127] It can be seen that the bottom surface of the step D on the first high acoustic resistance structure 22 shown in this way is towards the substrate 3, which can correspond Figure 4e to the structure of the step D shown in Figure 6b and the structure of the groove F shown in Figure 5 the step D towards the substrate 3, and Figure 6d the structure of the groove F towards the substrate 3. It should be understood that, Figure 8 and Figure 10 The preparation method shown is for the structure of the Bragg reflection layer 2 with only the first high acoustic resistance structure 22, and when the Bragg reflection layer 2 also has the second high acoustic resistance structure 23 buried therein (as Figure 4a shown), the preparation method thereof can be increased according to the structure of the second high acoustic resistance structure 23 to add the corresponding second high acoustic resistance structure 23 preparation step, which will not be described here.

[0128] The above resonator can be connected according to a certain topological structure to construct a frequency filter device, and therefore, the present application also provides a specific filter, please refer to Figure 12A filter 100 with a ladder structure is shown, which includes an input terminal 10, an output terminal 20, a series branch S, a first parallel branch P1, and a first filter unit 31. The series branch S is connected at one end to the input terminal 10 and at the other end to the output terminal 20. The first parallel branch P1 is connected at one end to the series branch S and at the other end to ground. The first filter unit 31 includes a first series resonator 311 arranged on the series branch S and a first parallel resonator 312 arranged on the first parallel branch P1. The first series resonator 311 is provided with a structure capable of suppressing a boundary mode harmonic.

[0129] In one possible implementation, the structure of the first series resonator 311 can refer to the structure of the resonator provided in the above-described embodiments (for example, as shown in Figure 3c , Figures 4b to 4e , Figure 5 , Figure 6a , Figure 6c and Figure 6d According to the above-described embodiments, the resonator with such a structure can effectively suppress the boundary mode harmonic. The first parallel resonator 312 can also be provided with a structure for suppressing the boundary mode harmonic, for example, the first parallel resonator 312 can also be selected from the resonators provided in the above-described embodiments. Of course, the first parallel resonator 312 can also be selected from ordinary resonators.

[0130] Further expanding the filter structure shown in Figure 12 can obtain a filter 100 as shown in Figure 13 The difference between the filter 100 shown in Figure 12 and the structure of the filter 100 is that the filter 100 further includes a second parallel branch P2 and a second filter unit 32. One end of the second parallel branch P2 is connected to the series branch S, and the other end is connected to ground. The second parallel branch P2 is equivalent to being arranged in parallel with the first parallel branch P1. The structure of the second filter unit 32 is similar to that of the first filter unit 31. The second filter unit 32 includes a second series resonator 321 arranged on the series branch S and a second parallel resonator 322 arranged on the second parallel branch P2. The structure of the second series resonator 321 can be similar to that of the first series resonator 321.

[0131] By analogy, a filter 100 as shown in Figure 14 is provided with a plurality of filter units similar to the first filter unit 31 between the input terminal 10 and the output terminal 20. Each filter unit includes a series resonator arranged on a series branch (for example, the first series resonator 311 on the series branch S in the first filter unit 31 as shown in Figure 14 ) and a parallel resonator arranged on a parallel branch (for example, the first parallel resonator 312 on the first parallel branch P1 in the first filter unit 31 as shown inFigure 14 The first parallel resonator 312 on the first parallel branch P1 in the example); wherein, all series resonators can be selected from the resonators provided in the above embodiment, and the filter 100 is simulated and analyzed to obtain Figure 15a The passband waveform N2 of the filter 100 is compared with the passband waveform N1 of the traditional filter, where the horizontal axis is frequency and the vertical axis is insertion loss. It can be seen that the use of the above-mentioned resonator as the series resonator in the filter 100 can effectively improve the passband of the filter 100.

[0132] Of course, in Figure 14 In the filter 100 shown in the example, all parallel resonators can also be selected from the resonators provided in the above embodiment, but the improvement effect is relatively small; for details, please refer to Figure 15b As shown, N2 is the passband waveform of the filter in which all the series resonators are the resonators provided by the above embodiment, and N3 is the passband waveform of the filter in which all the parallel resonators are the resonators provided by the above embodiment. It can be seen that the waveform improvement effect of the filter passband by using the resonators provided by the above embodiment is not obvious; therefore, the filter provided by the embodiment of the present application uses the resonators provided by the above embodiment at least in the series resonator part.

[0133] The present application also provides an electronic device 200. Figure 16 The electronic device 200 may include a transceiver 201, a memory 202 and a processor 203. The transceiver 201 is provided with the filter 100. The structure of the filter 100 may refer to Figures 12 to 14 One of the structures shown is an example.

[0134] It should be understood that the electronic device 200 here can be specifically a terminal device such as a smart phone, a computer, a smart watch, etc. Figure 17 The smartphone 210 shown is used as an example, which may specifically include a processor 2102, a memory 2103, a control circuit, an antenna, and input / output devices. The processor 2102 is mainly used to process communication protocols and communication data, as well as to control the entire smartphone, execute software programs, and process software program data, for example, to support the smartphone 210 in performing the actions described in the above method embodiment. The memory 2103 is mainly used to store software programs and data. The control circuit is mainly used to convert baseband signals into radio frequency signals and process radio frequency signals, and the control circuit includes the above-mentioned filter 100. The control circuit and antenna together can also be called a transceiver 2101, which is mainly used to transmit and receive radio frequency signals in the form of electromagnetic waves. Input / output devices, such as a touch screen, a display screen, a keyboard, etc., are mainly used to receive data input by the user and output data to the user.

[0135] When the smart phone 210 is powered on, the processor 2102 can read the software program of the memory 2103, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be transmitted wirelessly, the processor 2102 performs baseband processing on the data to be transmitted, and outputs the baseband signal to the radio frequency circuit. The radio frequency circuit converts the baseband signal into a radio frequency signal, and transmits the radio frequency signal in the form of electromagnetic waves through the antenna. When data is transmitted to the smart phone 210, the radio frequency circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor 2102. The processor 2102 converts the baseband signal into data and processes the data.

[0136] Those skilled in the art can understand that, for the convenience of description, Figure 17 Only one memory and one processor are shown. In actual terminal equipment, multiple processors and multiple memories can exist. The memory can also be referred to as a storage medium or a storage device, etc. It should be noted that the type of the memory is not limited in the embodiments of the present application.

[0137] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.​

Claims

1. A resonator characterized by, The resonator comprises: a substrate, a Bragg reflector and a piezoelectric layer arranged in sequence; a first electrode is arranged on the surface of the piezoelectric layer facing the Bragg reflector, and a second electrode is arranged on the surface of the piezoelectric layer away from the Bragg reflector; a boundary ring is arranged on the surface of the second electrode away from the piezoelectric layer, and the resonator has a first resonant region and a second resonant region corresponding to the boundary ring; in the stacking direction, the Bragg reflector comprises a low acoustic impedance structure and a first high acoustic impedance structure embedded in the low acoustic impedance structure; the first high acoustic impedance structure is provided with a discontinuous structure corresponding to the second resonant region.

2. The resonator of claim 1, wherein, The discontinuous structure overlaps with the second resonant region and does not overlap with the first resonant region.

3. The resonator of claim 2, wherein, The discontinuous structure comprises a groove arranged on the surface of the first high acoustic impedance structure.

4. The resonator of claim 2, wherein, The discontinuous structure comprises a step arranged on the edge of the first high acoustic impedance structure; the bottom surface of the step faces the piezoelectric layer; or, the bottom surface of the step faces the substrate.

5. The resonator of claim 4, wherein, In a plane perpendicular to the edge, the lateral dimension of the step is greater than 200 nm and less than the distance between the edge and the first resonant region, and the longitudinal dimension of the step is greater than 20 nm and less than the thickness of the first high acoustic impedance structure.

6. The resonator of claim 4, wherein, Two edges of the first high acoustic impedance structure are respectively provided with the step; In a plane perpendicular to each of the edges, the lateral dimension of each of the steps is different, and the longitudinal dimension of each of the steps is the same.

7. The resonator of claim 1, wherein, The discontinuous structure comprises a groove arranged on the surface of the first high acoustic impedance structure.

8. The resonator of claim 1, wherein, The discontinuous structure comprises a step arranged on the edge of the first high acoustic impedance structure; the bottom surface of the step faces the piezoelectric layer; or, the bottom surface of the step faces the substrate.

9. The resonator of claim 8, wherein, In a plane perpendicular to the edge, the lateral dimension of the step is greater than 200 nm and less than the distance between the edge and the first resonant region, and the longitudinal dimension of the step is greater than 20 nm and less than the thickness of the first high acoustic impedance structure.

10. The resonator of claim 8, wherein, Two edges of the first high acoustic impedance structure are respectively provided with the step; In a plane perpendicular to each of the edges, the lateral dimension of each of the steps is different, and the longitudinal dimension of each of the steps is the same.

11. The resonator of any one of claims 1-10, wherein, The Bragg reflector further comprises a second high acoustic impedance structure embedded in the low acoustic impedance structure; in the stacking direction, the second high acoustic impedance structure is parallel to the first high acoustic impedance structure, and the low acoustic impedance structure is arranged between the first high acoustic impedance structure and the second high acoustic impedance structure.

12. A filter, characterized by The resonator comprises: a substrate, a Bragg reflector and a piezoelectric layer arranged in sequence; a first electrode is arranged on the surface of the piezoelectric layer facing the Bragg reflector, and a second electrode is arranged on the surface of the piezoelectric layer away from the Bragg reflector; a boundary ring is arranged on the surface of the second electrode away from the piezoelectric layer, and the resonator has a first resonant region and a second resonant region corresponding to the boundary ring; in the stacking direction, the Bragg reflector comprises a low acoustic impedance structure and a first high acoustic impedance structure embedded in the low acoustic impedance structure; the first high acoustic impedance structure is provided with a discontinuous structure corresponding to the second resonant region. The discontinuous structure overlaps with the second resonant region and does not overlap with the first resonant region. The discontinuous structure comprises a groove arranged on the surface of the first high acoustic impedance structure. The discontinuous structure comprises a step arranged on the edge of the first high acoustic impedance structure; the bottom surface of the step faces the piezoelectric layer; or, the bottom surface of the step faces the substrate. In a plane perpendicular to the edge, the lateral dimension of the step is greater than 200 nm and less than the distance between the edge and the first resonant region, and the longitudinal dimension of the step is greater than 20 nm and less than the thickness of the first high acoustic impedance structure. Two edges of the first high acoustic impedance structure are respectively provided with the step; In a plane perpendicular to each of the edges, the lateral dimension of each of the steps is different, and the longitudinal dimension of each of the steps is the same. The Bragg reflector further comprises a second high acoustic impedance structure embedded in the low acoustic impedance structure; in the stacking direction, the second high acoustic impedance structure is parallel to the first high acoustic impedance structure, and the low acoustic impedance structure is arranged between the first high acoustic impedance structure and the second high acoustic impedance structure. The resonator comprises: an input terminal, an output terminal, a series branch, a first parallel branch and a first filter unit; one end of the series branch is connected to the input terminal, and the other end is connected to the output terminal; one end of the first parallel branch is connected to the series branch, and the other end is grounded; The first filter unit comprises a first series resonator arranged on the series branch and a first parallel resonator arranged on the first parallel branch, the first series resonator comprises a substrate, a Bragg reflector and a piezoelectric layer arranged in sequence, the piezoelectric layer is provided with a first electrode on the surface facing the Bragg reflector, and the piezoelectric layer is provided with a second electrode on the surface facing away from the Bragg reflector, and the second electrode is provided with a boundary ring on the surface facing away from the piezoelectric layer, so that the first series resonator has a first resonant region and a second resonant region corresponding to the boundary ring. Along the stacking direction, the Bragg reflector comprises a low acoustic impedance structure and a first high acoustic impedance structure embedded in the low acoustic impedance structure, and the first high acoustic impedance structure is provided with a discontinuous structure corresponding to the second resonant region.

13. The filter of claim 12, wherein, The discontinuous structure overlaps with the second resonant region and does not overlap with the first resonant region.

14. The filter of claim 13, wherein, The discontinuous structure comprises a groove arranged on the surface of the first high acoustic impedance structure.

15. The filter of claim 13, wherein, The discontinuous structure comprises a step arranged on the edge of the first high acoustic impedance structure. The bottom surface of the step faces the piezoelectric layer, or the bottom surface of the step faces the substrate.

16. The filter of claim 12, wherein, The discontinuous structure comprises a groove arranged on the surface of the first high acoustic impedance structure.

17. The filter of claim 12, wherein, The discontinuous structure comprises a step arranged on the edge of the first high acoustic impedance structure. The bottom surface of the step faces the piezoelectric layer, or the bottom surface of the step faces the substrate.

18. The filter of claim 12, wherein, The first parallel resonator is provided with a structure for suppressing boundary mode harmonics.

19. The filter of any one of claims 12-18, wherein, Further comprising a second parallel branch and a second filter unit. One end of the second parallel branch is connected to the series branch, and the other end is grounded. The second filter unit comprises a second series resonator connected to the series branch and a second parallel resonator connected to the second parallel branch, and the second series resonator is provided with a structure for suppressing boundary mode harmonics.

20. An electronic device, comprising: The transceiver, the memory and the processor are included; wherein the transceiver is provided with the filter as claimed in any one of claims 12-19.

21. A method of fabricating a resonator, comprising: The resonator has a first resonant region and a second resonant region, and the preparation method comprises the following steps: Providing a substrate; Arranging a Bragg reflector on the substrate; along the stacking direction, the Bragg reflector comprises a low acoustic impedance structure and a first high acoustic impedance structure embedded in the low acoustic impedance structure; the first high acoustic impedance structure is provided with a discontinuous structure corresponding to the second resonant region; Arranging a piezoelectric layer on the surface of the Bragg reflector, the piezoelectric layer has a first electrode on the surface facing the Bragg reflector, and the piezoelectric layer has a second electrode on the surface facing away from the Bragg reflector; Arranging a boundary ring on the surface of the second electrode facing away from the piezoelectric layer.

22. The production method according to claim 21, wherein The arrangement of the Bragg reflector on the substrate comprises the following steps: Depositing a low acoustic impedance material on the substrate to form a first low acoustic impedance layer; Depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer to form a first high acoustic impedance structure; Patterning the first high acoustic impedance structure; A low acoustic impedance material is deposited on the surface of the first high acoustic impedance structure to form a second low acoustic impedance layer, the second low acoustic impedance layer having an integral structure with the first low acoustic impedance layer to form a low acoustic impedance structure.

23. The production method according to claim 22, wherein The step of disposing a Bragg reflector layer on the substrate includes the steps of: depositing a low acoustic impedance material on the substrate to form a first low acoustic impedance layer; depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer to form a first high acoustic impedance layer; depositing a low acoustic impedance material around the first high acoustic impedance layer to level the surface of the first low acoustic impedance layer with the surface of the first high acoustic impedance layer; depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer and the first high acoustic impedance layer to form a second high acoustic impedance layer, the second high acoustic impedance layer having an integral structure with the first high acoustic impedance layer to form the first high acoustic impedance structure; depositing a low acoustic impedance material on the surface of the first high acoustic impedance structure to form a second low acoustic impedance layer, the second low acoustic impedance layer having an integral structure with the first low acoustic impedance layer to form a low acoustic impedance structure.

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