Surface acoustic wave resonator device and fabrication method therefor

Abstract

Disclosed in the present application is a surface acoustic wave resonator device. The surface acoustic wave resonator device has an interdigital electrode region, which comprises a first peripheral region, a first end region, a central region, a second end region and a second peripheral region arranged in sequence in a first direction. The surface acoustic wave resonator device comprises: an interdigital transducer disposed on a piezoelectric substrate and comprising a plurality of interdigital electrodes, wherein the plurality of interdigital electrodes are located in the interdigital electrode region and include first interdigital electrodes and second interdigital electrodes, which extend in the first direction and are alternately arranged in a second direction intersecting the first direction; an intermediate layer disposed on the piezoelectric substrate and covering the interdigital transducer; an acoustic velocity adjustment layer disposed on the side of at least a portion of the intermediate layer away from the piezoelectric substrate; and a passivation layer disposed on the side of the intermediate layer away from the piezoelectric substrate, wherein the acoustic velocity adjustment layer is located in the central region and overlaps, in a direction perpendicular to a primary surface of the piezoelectric substrate, the portions of the plurality of interdigital electrodes that are located in the central region. Further disclosed in the present application is a fabrication method for the surface acoustic wave resonator device.

Description

Surface acoustic wave resonator device and method of manufacturing the same

[0001] This application is based on and claims priority to Chinese Patent Application No. 202411032003.3, filed on July 29, 2024, U.S. Patent Application No. 19 / 027,371, filed on January 17, 2025, the contents of all of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0002] Embodiments of the present disclosure relate to a surface acoustic wave resonator device and a method of manufacturing the same. BACKGROUND

[0003] With the rapid development of mobile communication technology, filters using resonators as basic units are increasingly widely and massively applied in communication devices such as smart phones. As a kind of acoustic wave filter, the surface acoustic wave (SAW) filter has the advantages of small size and light weight, and is widely used in current communication devices. There is a spurious mode of transverse wave in the traditional surface acoustic wave resonator, and this spurious wave will affect the performance of the resonator. SUMMARY

[0004] The following presents a simplified summary of some aspects of the disclosed embodiments in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of the disclosure and is not intended to identify key / critical elements or to delineate the scope of the embodiments. Its sole purpose is to present some aspects of the disclosed embodiments in a simplified form as a prelude to the more detailed description that is presented later.

[0005] According to at least one embodiment of the present disclosure, there is provided a surface acoustic wave resonator device having an interdigital electrode region including a first peripheral region, a first end region, a center region, a second end region, and a second peripheral region arranged in order in a first direction, and including: a piezoelectric substrate; an interdigital transducer provided on the piezoelectric substrate and including a plurality of interdigital electrodes located in the interdigital electrode region and including a first interdigital electrode and a second interdigital electrode; the first interdigital electrode and the second interdigital electrode extending in the first direction and alternately arranged in a second direction intersecting the first direction; the first interdigital electrode extending from the first peripheral region to the second end region, the second interdigital electrode extending from the second peripheral region to the first end region; an intermediate layer provided on the piezoelectric substrate and covering the interdigital transducer; a sound velocity adjustment layer provided on a side of at least a portion of the intermediate layer away from the piezoelectric substrate; and a passivation layer provided on a side of the intermediate layer away from the piezoelectric substrate, wherein the sound velocity adjustment layer is located in the center region and overlaps with a portion of the plurality of interdigital electrodes located in the center region in a direction perpendicular to a main surface of the piezoelectric substrate, and is configured to change a sound velocity of the center region.

[0006] According to at least one embodiment of the present disclosure, there is provided a method of manufacturing a surface acoustic wave resonator device having an interdigital electrode region including a first peripheral region, a first end region, a center region, a second end region, and a second peripheral region arranged in order in a first direction, and including: providing a piezoelectric substrate; forming an interdigital transducer on the piezoelectric substrate, the interdigital transducer including a plurality of interdigital electrodes located in the interdigital electrode region and including a first interdigital electrode and a second interdigital electrode; the first interdigital electrode and the second interdigital electrode extending in the first direction and alternately arranged in a second direction intersecting the first direction; the first interdigital electrode extending from the first peripheral region to the second end region, the second interdigital electrode extending from the second peripheral region to the first end region; forming an intermediate layer on the piezoelectric substrate to cover the interdigital transducer; forming a sound velocity adjustment layer on a side of at least a portion of the intermediate layer away from the piezoelectric substrate; and forming a passivation layer on a side of the intermediate layer away from the piezoelectric substrate, wherein the sound velocity adjustment layer is located in the center region and overlaps with a portion of the plurality of interdigital electrodes located in the center region in a direction perpendicular to a main surface of the piezoelectric substrate, and is configured to change a sound velocity of the center region.

[0007] The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application. BRIEF DESCRIPTION OF DRAWINGS

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following will briefly introduce the drawings of the embodiments. Obviously, the drawings described in the following description are only some of the embodiments of the present disclosure and not limit the present disclosure.

[0009] FIG. 1A shows a schematic plan view of a surface acoustic wave resonator device according to some embodiments of the present disclosure.

[0010] FIG. 1B shows a schematic enlarged plan view of an interdigital transducer in the surface acoustic wave resonator device shown in FIG. 1A according to some embodiments of the present disclosure.

[0011] FIGS. 2A and 2B show schematic cross-sectional views of a surface acoustic wave resonator device according to some embodiments of the present disclosure, and are cross-sectional views taken along lines A-A’ and B-B’ of FIG. 1A, respectively.

[0012] FIGS. 3A to 3H show schematic cross-sectional views of a surface acoustic wave resonator device according to some alternative embodiments of the present disclosure, taken along line A-A’ of FIG. 1A.

[0013] FIG. 4A shows a schematic plan view of a surface acoustic wave resonator device according to further embodiments of the present disclosure.

[0014] FIG. 4B shows a schematic enlarged plan view of an interdigital transducer in the surface acoustic wave resonator device shown in FIG. 4A according to further embodiments of the present disclosure.

[0015] FIGS. 5A and 5B show schematic cross-sectional views of a surface acoustic wave resonator device according to further embodiments of the present disclosure, and are cross-sectional views taken along lines A-A’ and B-B’ of FIG. 4A, respectively.

[0016] FIGS. 6A to 6H show schematic cross-sectional views of a surface acoustic wave resonator device according to some alternative embodiments of the present disclosure, taken along line A-A’ of FIG. 4A.

[0017] FIG. 7A shows a schematic plan view of a surface acoustic wave resonator device according to further alternative embodiments of the present disclosure.

[0018] FIG. 7B shows a schematic cross-sectional view of the surface acoustic wave resonator device according to further alternative embodiments of the present disclosure, taken along line B-B’ of FIG. 7A.

[0019] FIG. 8A shows a schematic plan view of a surface acoustic wave resonator device according to further embodiments of the present disclosure.

[0020] FIG. 8B shows a schematic enlarged plan view of an interdigital transducer in the surface acoustic wave resonator device shown in FIG. 8A according to further embodiments of the present disclosure.

[0021] FIGS. 9A and 9B show schematic cross-sectional views of a surface acoustic wave resonator device according to further embodiments of the present disclosure, and are cross-sectional views taken along lines A-A’ and B-B’ of FIG. 8A, respectively.

[0022] FIGS. 10A to 10H show schematic cross-sectional views of a surface acoustic wave resonator device taken along line A-A’ of FIG. 8A according to some alternative embodiments of the present disclosure.

[0023] FIG. 11A shows a schematic plan view of a surface acoustic wave resonator device according to further alternative embodiments of the present disclosure.

[0024] FIG. 11B shows a schematic cross-sectional view of the surface acoustic wave resonator device of FIG. 11A taken along line B-B’ according to further alternative embodiments of the present disclosure.

[0025] FIG. 12A shows a schematic plan view of a surface acoustic wave resonator device according to yet further embodiments of the present disclosure.

[0026] FIG. 12B shows a schematic enlarged plan view of an interdigital transducer in the surface acoustic wave resonator device of FIG. 12A according to yet further embodiments of the present disclosure.

[0027] FIGS. 13A and 13B show schematic cross-sectional views of a surface acoustic wave resonator device according to yet further embodiments of the present disclosure, and are cross-sectional views taken along lines A-A’ and B-B’ of FIG. 12A, respectively.

[0028] FIGS. 14A to 14H show schematic cross-sectional views of a surface acoustic wave resonator device taken along line A-A’ of FIG. 12A according to yet further alternative embodiments of the present disclosure.

[0029] FIG. 15A shows a schematic plan view of a surface acoustic wave resonator device according to yet further alternative embodiments of the present disclosure.

[0030] FIG. 15B shows a schematic cross-sectional view of the surface acoustic wave resonator device of FIG. 15A taken along line B-B’ according to yet further alternative embodiments of the present disclosure.

[0031] FIG. 16 shows a schematic plan view of a surface acoustic wave resonator device according to still further embodiments of the present disclosure. DETAILED DESCRIPTION

[0032] In order to make the objects, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some of, but not all of, the embodiments of the present disclosure. Based on the described embodiments of the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present disclosure.

[0033] The reference in the specification to any prior art does not, and should not be taken as an acknowledgement or admission that the prior art forms part of the common general knowledge of the skilled in the art in the applicant's country of origin or in any other jurisdiction, or that the prior art is known to be relevant to an attempt to solve any problem with which the present application is concerned.

[0034] Unless otherwise defined, technical terms or scientific terms used in the present disclosure shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. The terms "first", "second", and similar terms do not denote any order, quantity, or importance, but are used to distinguish different components. The terms "include", "comprise", and similar terms are intended to mean that the elements or objects listed after the terms encompass the elements or objects recited after the terms, and equivalents thereof, without precluding other elements or objects. The terms "connected" or "coupled" and similar terms are not limited to physical or mechanical connections or couplings, but can include electrical connections or couplings, whether direct or indirect. The term "and / or" is a descriptive term that refers to three possible relationships: A and / or B, A or B, and A and B.

[0035] Embodiments of the present disclosure provide a surface acoustic wave resonator device, a manufacturing method thereof, and a filter including the same, which can effectively suppress spurious waves in the resonator, avoid or reduce energy loss, and thus improve device performance.

[0036] For example, a surface acoustic wave resonator device of an embodiment of the present disclosure has an interdigital electrode region including a first peripheral region, a first end region, a center region, a second end region, and a second peripheral region arranged in order in a first direction, and includes: a piezoelectric substrate; an interdigital transducer disposed on the piezoelectric substrate and including a plurality of interdigital electrodes located in the interdigital electrode region and including a first interdigital electrode and a second interdigital electrode; the first interdigital electrode and the second interdigital electrode extending in the first direction and alternately arranged in a second direction intersecting the first direction; the first interdigital electrode extending from the first peripheral region to the second end region, and the second interdigital electrode extending from the second peripheral region to the first end region; an intermediate layer disposed on the piezoelectric substrate and covering the interdigital transducer; a sound velocity adjustment layer disposed on a side of at least a portion of the intermediate layer away from the piezoelectric substrate; and a passivation layer disposed on a side of the intermediate layer away from the piezoelectric substrate, wherein the sound velocity adjustment layer is located in the center region and overlaps with a portion of the plurality of interdigital electrodes located in the center region in a direction perpendicular to a main surface of the piezoelectric substrate, and is configured to change a sound velocity of the center region.

[0037] In the embodiments of the present disclosure, the sound velocity adjustment layer is arranged in the center region of the interdigital electrode region to change the sound velocity of the center region, so that the sound velocity difference between the center region and other regions such as the end region can be achieved, and the effect of suppressing spurious waves can be achieved.

[0038] FIG. 1A shows a schematic plan view of a surface acoustic wave resonator device according to some embodiments of the present disclosure. FIG. 1B shows a schematic enlarged plan view of an interdigital transducer in the surface acoustic wave resonator device shown in FIG. 1A according to some embodiments of the present disclosure. FIGS. 2A and 2B show schematic cross-sectional views of a surface acoustic wave resonator device according to some embodiments of the present disclosure, and are cross-sectional views taken along lines A-A’ and B-B’ of FIG. 1A, respectively.

[0039] Referring to FIGS. 1A, 1B, and 2A, 2B, in some embodiments, the surface acoustic wave resonator device 500 has an interdigital electrode region IR including a center region C, a first end region E1, a second end region E2, a first peripheral region R1, and a second peripheral region R2, and includes a piezoelectric substrate 100, an interdigital transducer 150, an intermediate layer 160, a sound velocity adjustment layer 170, and a passivation layer 180. For example, the first peripheral region R1, the first end region E1, the center region C, the second end region E2, and the second peripheral region R2 are sequentially arranged in a first direction D1.

[0040] In some embodiments, the interdigital transducer 150 is arranged on the piezoelectric substrate 100 and includes a plurality of interdigital electrodes and a first bus bar 111 and a second bus bar 121. For example, the plurality of interdigital electrodes are located in the interdigital electrode region IR and include a first interdigital electrode 110 and a second interdigital electrode 120; the plurality of interdigital electrodes extend substantially parallel to each other in the first direction D1 and are arranged in a second direction D2, the first direction D1 and the second direction D2 are parallel to a main surface (e.g., a surface close to or in contact with the interdigital transducer 150) of the piezoelectric substrate 100 and intersect each other, for example, are substantially perpendicular to each other. For example, the first interdigital electrode 110 and the second interdigital electrode 120 extend in the first direction D1 and are alternately arranged in the second direction D2.

[0041] The first bus bar 111 and the second bus bar 121 are located on opposite sides of the interdigital electrode region IR in the first direction D1 and are connected with the first interdigital electrode 110 and the second interdigital electrode 120, respectively. The first interdigital electrode 110 extends from the first peripheral region R1 to the second end region E2, and the second interdigital electrode 120 extends from the second peripheral region R2 to the first end region E1. That is, the first interdigital electrode 110 continuously extends in the first peripheral region R1, the first end region E1, the central region C, and the second end region E2; and the second interdigital electrode 120 continuously extends in the second peripheral region R2, the second end region E2, the central region C, and the first end region E1. The first interdigital electrode 110 is not disposed in the second peripheral region R2 and is spaced apart from the second bus bar 121 by the second peripheral region R2. The second interdigital electrode 120 is not disposed in the first peripheral region R1 and is spaced apart from the first bus bar 111 by the first peripheral region R1.

[0042] In some embodiments, the intermediate layer 160 is disposed on the piezoelectric substrate 100 and covers the interdigital transducer 150, i.e., the intermediate layer 160 is disposed on the side of the piezoelectric substrate 100 having the interdigital transducer 150. For example, the intermediate layer 160 covers the plurality of interdigital electrodes of the interdigital transducer 150, the sidewalls of the first and second bus bars, and the surfaces of the first and second bus bars away from the piezoelectric substrate 100.

[0043] In some embodiments, the surface acoustic wave resonator device 500 can be or include a temperature compensated surface acoustic wave (TC-SAW) resonator device, and the intermediate layer 160 can include a temperature compensation layer. For example, at least a portion of the intermediate layer 160 can be the temperature compensation layer. In some embodiments, the intermediate layer 160 can only include the temperature compensation layer; in some embodiments, the intermediate layer 160 can further include a protective layer located on the side of the temperature compensation layer close to the piezoelectric substrate, which separates the temperature compensation layer and the interdigital transducer, thereby protecting the interdigital transducer from being oxidized during the process of forming the temperature compensation layer.

[0044] For example, the intermediate layer 160 can include one or more of silicon oxide (SiO2), silicon nitride (SiN), aluminum nitride (AIN), amorphous silicon, gallium nitride, etc. The intermediate layer 160 can be a single layer or a multi-layer structure. For example, the intermediate layer 160 can be a single layer structure and include a silicon oxide material; or the intermediate layer 160 can be a multi-layer structure and include a stack of a silicon oxide layer and a non-silicon oxide layer formed of a silicon nitride (SiN), aluminum nitride (AIN), amorphous silicon, gallium nitride, etc. material, where the non-silicon oxide layer is disposed at least between the silicon oxide layer and the interdigital transducer, or can also be disposed between the silicon oxide layer and the piezoelectric substrate. The silicon oxide layer can have a thickness much greater than that of the non-silicon oxide layer and serve as a temperature compensation layer. The non-silicon oxide layer can protect the interdigital transducer from being oxidized during the formation of the silicon oxide layer, i.e., serve as a protective layer.

[0045] In some embodiments, the acoustic velocity adjustment layer 170 is disposed on a side of at least a portion of the intermediate layer 160 distal to the piezoelectric substrate 100. The passivation layer 180 is disposed on a side of the intermediate layer 160 distal to the piezoelectric substrate. For example, the acoustic velocity adjustment layer 170 is located in the central region C and overlaps with the portions of the plurality of interdigital electrodes located in the central region C in a direction perpendicular to the major surface of the piezoelectric substrate 100 (e.g., the third direction D3) and is configured to change the acoustic velocity of the central region C. For example, the acoustic velocity adjustment layer 170 is configured to speed up the acoustic velocity of the central region C and make the acoustic velocity of the central region C different from (e.g., higher than) the acoustic velocities of the first end region E1 and the second end region E2, i.e., make the central region and the end regions have a difference in acoustic velocity. In this context, the “acoustic velocity” of a region refers to the propagation speed of acoustic waves in the region; the overlapping of a plurality of components in a direction means that the normal projections of the plurality of components on a reference plane perpendicular to the direction overlap with each other. That is, the normal projection of the acoustic velocity adjustment layer 170 on the major surface of the piezoelectric substrate 100 overlaps with the normal projection of the plurality of interdigital electrodes on the major surface of the piezoelectric substrate. In some embodiments, the normal projection of the portions of the plurality of interdigital electrodes located in the central region on the piezoelectric substrate can be located within the normal projection of the acoustic velocity adjustment layer on the piezoelectric substrate.

[0046] It should be understood that, in this context, the interdigital electrode region not only includes the layer in which the interdigital electrodes are located, but also includes the layers overlapping with the interdigital transducer in a direction perpendicular to the major surface of the piezoelectric substrate; and the interdigital electrode region not only includes the interdigital regions in which the interdigital electrodes are located and the regions overlapping with the interdigital regions in a direction perpendicular to the major surface of the piezoelectric substrate, but also includes the regions between the plurality of interdigital electrodes, the regions between the interdigital electrodes and the bus bars, and the regions overlapping with the regions in a direction perpendicular to the major surface of the piezoelectric substrate.

[0047] Referring to FIG. IB, in the interdigital electrode region, in the first direction D1, the first end region E1 and the second end region E2 are located on opposite sides of the center region C, the first peripheral region R1 is located on a side of the first end region E1 away from the center region C, and the second peripheral region R2 is located on a side of the second end region E2 away from the center region C. The first end region and the second end region can be collectively referred to as end regions or interdigital electrode end regions; the first peripheral region and the second peripheral region can be collectively referred to as peripheral regions or interdigital electrode peripheral regions; and the center region can be referred to as an interdigital electrode center region or an interdigital electrode active region.

[0048] For example, each of the plurality of interdigital electrodes includes a center portion, a first end portion, a second end portion, and a connecting portion; wherein the center portion is located in the center region, the first end portion is located in one of the first end region and the second end region, the second end portion is located in the other of the first end region and the second end region, and the connecting portion is located in one of the first peripheral region and the second peripheral region. In each interdigital electrode, the first end portion and the second end portion are located on opposite sides of the center portion in the first direction, the connecting portion is located on a side of the first end portion away from the center portion, and the connecting portion is connected to the first end portion and the corresponding bus bar.

[0049] For example, the center portion 10, the first end portion 11, the second end portion 12, and the connecting portion 13 of the first interdigital electrode 110 are located in the center region C, the first end region E1, the second end region E2, and the first peripheral region R1, respectively; the center portion 20, the first end portion 21, the second end portion 22, and the connecting portion 23 of the second interdigital electrode 120 are located in the center region C, the second end region E2, the first end region E1, and the second peripheral region R2, respectively; and the portions of the plurality of interdigital electrodes located in the center region include the center portion 10 of the first interdigital electrode 110 and the center portion 20 of the second interdigital electrode 120, i.e., the orthographic projection of the center portion 10 of the first interdigital electrode 110 and the center portion 20 of the second interdigital electrode 120 on the piezoelectric substrate is located within the orthographic projection of the sound velocity adjustment layer 170 on the piezoelectric substrate 100. The first end portion 11 and the second end portion 12 of the first interdigital electrode 110 collectively constitute an end portion of the first interdigital electrode, and the first end portion 21 and the second end portion 22 of the second interdigital electrode 120 collectively constitute an end portion of the second interdigital electrode.

[0050] In some embodiments, portions of the plurality of interdigital electrodes located in regions other than the central region of the interdigital electrode region do not overlap with the acoustic velocity adjustment layer. For example, the portions of the plurality of interdigital electrodes located in the first end region, the second end region, the first peripheral region, and the second peripheral region do not overlap with the acoustic velocity adjustment layer in the orthographic projection on the piezoelectric substrate. In this context, the orthographic projection of a plurality of members on a reference plane being offset includes the case where the orthographic projections of the plurality of members are spaced apart from each other without overlapping, and also includes the case where the orthographic projections of the plurality of members are adjacent to each other without overlapping.

[0051] For example, the orthographic projections on the piezoelectric substrate 100 of the first end portions 11, the second end portions 12, and the connecting portions 13 of the plurality of first interdigital electrodes 110, and the orthographic projections on the piezoelectric substrate 100 of the first end portions 21, the second end portions 22, and the connecting portions 23 of the plurality of second interdigital electrodes 120 are offset from the orthographic projection on the piezoelectric substrate 100 of the acoustic velocity adjustment layer 170. For example, the orthographic projections on the piezoelectric substrate of the first bus bars 111 and the second bus bars 121 of the interdigital transducer 150 are also offset from the orthographic projection on the piezoelectric substrate of the acoustic velocity adjustment layer 170.

[0052] In some embodiments, the acoustic velocity adjustment layer 170 has a first side wall and a second side wall opposite to each other in the second direction D2, the first side wall and the second side wall extend along the first direction D1, and each can be aligned with an outer side wall of an outermost interdigital electrode (a first interdigital electrode or a second interdigital electrode) of the plurality of interdigital electrodes in the second direction D2 away from other interdigital electrodes. For example, as shown in FIG. 1B, the first side wall of the acoustic velocity adjustment layer 170 can be substantially aligned with the outer side wall of the outermost first interdigital electrode 110 in the third direction D3 perpendicular to the main surface of the piezoelectric substrate; the second side wall of the acoustic velocity adjustment layer 170 can be substantially aligned with the outer side wall of the outermost second interdigital electrode 120 in the third direction D3 perpendicular to the main surface of the piezoelectric substrate.

[0053] In alternative embodiments, the acoustic velocity adjustment layer can also extend beyond one or both of the outer side walls of the two outermost interdigital electrodes of the plurality of interdigital electrodes in the second direction. For example, the acoustic velocity adjustment layer 170 can extend beyond the outer side wall of the outermost first interdigital electrode 110 in the second direction D2 away from other interdigital electrodes; and / or the acoustic velocity adjustment layer 170 can extend beyond the outer side wall of the outermost second interdigital electrode 120 in the second direction D2 away from other interdigital electrodes.

[0054] For example, the acoustic velocity adjustment layer 170 is configured to change the acoustic velocity of the region where it is located, e.g., to increase the acoustic velocity of the region where it is located. Thus, a region provided with the acoustic velocity adjustment layer can have a difference in acoustic velocity with a region not provided with the acoustic velocity adjustment layer. For example, by providing the acoustic velocity adjustment layer in the center region of the interdigital transducer, but not in other regions such as the end regions of the interdigital transducer, the acoustic velocity of the center region of the interdigital transducer can be made higher than the acoustic velocity of the other regions such as the end regions of the interdigital transducer. For example, the acoustic velocity adjustment layer 170 can also be referred to as a high acoustic velocity layer, and a region provided with the layer (e.g., the center region) can also be referred to as a high acoustic velocity region.

[0055] In some embodiments, the acoustic velocity adjustment layer 170 can include a material different from the material of the intermediate layer 160. For example, the intermediate layer 160 includes a temperature compensation layer, and the acoustic velocity adjustment layer 170 and the temperature compensation layer include different materials. For example, the acoustic velocity adjustment layer 170 includes silicon nitride (SiN x ), aluminum nitride, or a combination thereof. The passivation layer 180 can include a material the same as or different from the material of the acoustic velocity adjustment layer 170. For example, the passivation layer 180 can include silicon oxide (SiO2), silicon nitride (SiN x ), or a combination thereof.

[0056] In some embodiments, the intermediate layer has a recess, and at least a portion of the acoustic velocity adjustment layer is located in the recess of the intermediate layer. The passivation layer can or can not cover the surface of the acoustic velocity adjustment layer away from the intermediate layer. For example, the passivation layer can be located in a region outside the recess of the intermediate layer without covering the acoustic velocity adjustment layer. The acoustic velocity adjustment layer can be offset from the passivation layer in a normal projection on the piezoelectric substrate. In other embodiments, the passivation layer can also cover the surface of the acoustic velocity adjustment layer away from the piezoelectric substrate.

[0057] In embodiments in which the intermediate layer has a recess, the thickness of the acoustic velocity adjustment layer in a direction perpendicular to the main surface of the piezoelectric substrate can be the same as or different from the height of the recess in the direction perpendicular to the main surface of the piezoelectric substrate. For example, the thickness of the acoustic velocity adjustment layer can be substantially equal to the height of the recess; in this example, the surface of the acoustic velocity adjustment layer away from the piezoelectric substrate can be substantially flush with the surface of the intermediate layer away from the piezoelectric substrate in a direction parallel to the main surface of the piezoelectric substrate. In other embodiments, the thickness of the acoustic velocity adjustment layer can be greater than or less than the height of the recess; in this example, the distance of the surface of the acoustic velocity adjustment layer away from the piezoelectric substrate from the main surface of the piezoelectric substrate in a direction perpendicular to the main surface of the piezoelectric substrate is greater than or less than the distance of the surface of the intermediate layer away from the piezoelectric substrate (e.g., the surface contacting the passivation layer) from the main surface of the piezoelectric substrate.

[0058] For example, referring to FIG. 2A, the intermediate layer 160 has a recess 161, and the thickness of the acoustic velocity adjustment layer 170 can be greater than the height of the recess 161 of the intermediate layer 160. For example, a portion of the acoustic velocity adjustment layer 170 is located in the recess 161, and the acoustic velocity adjustment layer 170 has a protruding portion that protrudes beyond the surface of the intermediate layer 160 on the side farthest from the piezoelectric substrate 100 in a direction perpendicular to the main surface of the piezoelectric substrate 100. In this example, the surface of the acoustic velocity adjustment layer 170 on the side farthest from the piezoelectric substrate 100 is farther from the main surface of the piezoelectric substrate 100 than the surface of the intermediate layer 160 on the side farthest from the piezoelectric substrate 100 in a direction perpendicular to the main surface of the piezoelectric substrate 100. The sidewall of the protruding portion of the acoustic velocity adjustment layer 170 can be in contact with the passivation layer 180.

[0059] In some embodiments, the orthogonal projection of the acoustic velocity adjustment layer 170 on the piezoelectric substrate 100 is within the orthogonal projection of the recess 161 of the intermediate layer 160 on the piezoelectric substrate 100. For example, the orthogonal projection of the acoustic velocity adjustment layer 170 can substantially coincide with the orthogonal projection of the recess 161, and the area of the orthogonal projection of the acoustic velocity adjustment layer 170 can be substantially equal to the area of the orthogonal projection of the recess 161.

[0060] In some embodiments, the passivation layer 180 covers the area of the intermediate layer 160 outside the recess. In this example, the surface of the acoustic velocity adjustment layer 170 on the side farthest from the piezoelectric substrate 100 can not be covered by the passivation layer 180; the orthogonal projection of the acoustic velocity adjustment layer 170 on the piezoelectric substrate 100 is offset from the orthogonal projection of the passivation layer 180 on the piezoelectric substrate 100. For example, the acoustic velocity adjustment layer 170 and the recess 160 are disposed in the center region of the interdigital electrode, and the passivation layer 180 is disposed in other regions other than the center region of the interdigital electrode.

[0061] Continuing to refer to FIG. 2A, in other words, the intermediate layer 160 can include a first portion 160a and a second portion 160b, the first portion 160a has a first thickness, and the second portion 160b has a second thickness, and the first thickness is smaller than the second thickness. Here, the first thickness and the second thickness of the intermediate layer are the thicknesses of the respective portions of the intermediate layer in a direction perpendicular to the main surface of the piezoelectric substrate. The recess 161 is bounded by the surface of the first portion 160a of the intermediate layer 160 on the side farthest from the piezoelectric substrate and the sidewall of the second portion 160b. The acoustic velocity adjustment layer 170 and the passivation layer 180 cover the first portion 160a and the second portion 160b of the intermediate layer 160, respectively. In some embodiments, the recess 161 is disposed in the center region of the interdigital electrode without extending into the terminal region and the peripheral region of the interdigital electrode. That is, the first portion 160a with the smaller thickness is located in the center region of the interdigital electrode without being disposed in the terminal region and the peripheral region of the interdigital electrode; the second portion 160b with the larger thickness can be located in the terminal region and the peripheral region of the interdigital electrode.

[0062] In some embodiments, the acoustic velocity adjustment layer 170 comprises silicon nitride, aluminum nitride, or a combination thereof; and the passivation layer 180 comprises silicon oxide, silicon nitride, or a combination thereof. The acoustic velocity adjustment layer 170 and the passivation layer 180 comprise the same or different materials. In some examples, in the case that the passivation layer 180 also comprises silicon nitride, the thickness of the acoustic velocity adjustment layer 170 can be set to be greater (e.g., much greater) than the thickness of the passivation layer 180, such that the acoustic velocity adjustment layer 170 has a greater (e.g., much greater) effect on increasing the acoustic velocity in the center region of the interdigital electrode than the passivation layer 180 has on increasing the acoustic velocity in other regions of the interdigital electrode, so as to cause the acoustic velocity in the center region of the interdigital electrode to be greater than the acoustic velocity in other regions (e.g., the first end region and the second end region) of the interdigital electrode, i.e., to cause a difference in acoustic velocity between the center region and the end regions of the interdigital electrode.

[0063] In some embodiments, the recess of the intermediate layer 161 is provided in the temperature compensation layer (e.g., the silicon oxide layer) thereof. Providing the recess in the intermediate layer causes the thickness of the first portion of the intermediate layer to be thinned, e.g., the thickness of the temperature compensation layer to be thinned. For example, thinning the thickness of the first portion of the intermediate layer can also be beneficial for increasing the acoustic velocity in that region. For example, the material of the temperature compensation layer (e.g., silicon oxide) has an effect of slowing down the acoustic velocity, and thus thinning the thickness of the layer by forming a recess in the temperature compensation layer can also achieve the effect of increasing the acoustic velocity in that region. That is, by providing the recess in the intermediate layer and the acoustic velocity adjustment layer being provided in the recess of the intermediate layer, the acoustic velocity in the center region can be further increased, and the difference in acoustic velocity between the center region and the end regions can be increased, so as to further improve the effect of suppressing the spurious signals.

[0064] FIGS. 3A-3H show schematic cross-sectional views of a surface acoustic wave resonator device taken along line A-A’ of FIG. 1A, according to some other embodiments of the present disclosure.

[0065] Referring to FIG. 3A, in some embodiments, the acoustic velocity adjustment layer 170 is located in the recess 161 of the intermediate layer 160, and the thickness of the acoustic velocity adjustment layer 170 can be substantially equal to the depth of the recess 161 of the intermediate layer 160. For example, the acoustic velocity adjustment layer 170 can be located entirely in the recess 161 of the intermediate layer 160, and the surface of the acoustic velocity adjustment layer 170 distal to the piezoelectric substrate 100 can be substantially flush with the surface of the intermediate layer 160 distal to the piezoelectric substrate 100 in a direction parallel to the main surface of the piezoelectric substrate.

[0066] Referring to FIG. 3B, in some embodiments, the acoustic velocity adjustment layer 170 is located in the recess 161 of the intermediate layer 160, and the thickness of the acoustic velocity adjustment layer 170 can be less than the depth of the recess 161 of the intermediate layer 160. For example, the acoustic velocity adjustment layer 170 is entirely located in the recess 161 of the intermediate layer 160, and the surface of the acoustic velocity adjustment layer 170 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate 100 is lower than the surface of the intermediate layer 160 (e.g., the second portion thereof) away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate. That is, in the direction perpendicular to the main surface of the piezoelectric substrate, the distance from the surface of the acoustic velocity adjustment layer 170 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate to the main surface of the piezoelectric substrate is less than the distance from the surface of the intermediate layer 160 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate to the main surface of the piezoelectric substrate.

[0067] In the examples of FIGS. 3A and 3B, the surface of the acoustic velocity adjustment layer 170 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate can not be covered by the passivation layer 180, and the relative positional relationship and structural features between the acoustic velocity adjustment layer 170 and the passivation layer 180 are similar to those described above with reference to FIG. 2A in the foregoing embodiments, and will not be described herein again.

[0068] Referring to FIGS. 3C to 3E, in some embodiments, at least part of the acoustic velocity adjustment layer 170 is located in the recess 161 of the intermediate layer 160, and the surface of the acoustic velocity adjustment layer 170 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate can be covered by the passivation layer 180. For example, the passivation layer 180 can continuously extend on the intermediate layer 160 and the acoustic velocity adjustment layer 170, and cover the surfaces of the intermediate layer 160 and the acoustic velocity adjustment layer 170 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate. In this example, the thickness of the acoustic velocity adjustment layer 170 can be greater than, substantially equal to, or less than the depth of the recess 161 of the intermediate layer 160. FIG. 3C shows an example in which the thickness of the acoustic velocity adjustment layer 170 is greater than the recess depth, in which the passivation layer 180 covers the surface of the acoustic velocity adjustment layer 170 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate, and covers the sidewall of the protruding portion of the acoustic velocity adjustment layer 170. In alternative embodiments, as shown in FIG. 3D, the thickness of the acoustic velocity adjustment layer 170 can also be substantially equal to the recess depth, such that the surfaces of the acoustic velocity adjustment layer 170 and the intermediate layer 160 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate are substantially flush, the passivation layer 180 covers the acoustic velocity adjustment layer 170 and the intermediate layer 160, and can have a substantially flat surface.

[0069] In other alternative embodiments, as shown in FIG. 3E, the thickness of the acoustic velocity adjustment layer 170 can also be less than the recess depth, the passivation layer 180 covers the intermediate layer 160, and can also extend into the recess to fill the portion of the recess not filled by the acoustic velocity adjustment layer; part of the passivation layer 180 covers the surface of the acoustic velocity adjustment layer 170 away from the piezoelectric substrate on the side opposite to the main surface of the piezoelectric substrate, and can cover part of the sidewall of the recess.

[0070] Referring to FIG. 3F, in some other embodiments, the acoustic velocity adjustment layer 170 can also be disposed on the side of the passivation layer 180 distal to the piezoelectric substrate, and cover part of the surface of the passivation layer 180. For example, the passivation layer 180 continuously extends on the intermediate layer 160, and can substantially cover the entire surface of the intermediate layer 160. The acoustic velocity adjustment layer 170 covers part of the passivation layer 180 in the central region of the interdigital electrode region, and the acoustic velocity adjustment layer 170 and the intermediate layer 160 are spaced apart by the part of the passivation layer 180 therebetween.

[0071] Referring to FIG. 3G, in some other embodiments, the acoustic velocity adjustment layer 170 can be embedded in the intermediate layer 160, and the surface of the acoustic velocity adjustment layer 170 distal to the piezoelectric substrate 100 can be covered by the intermediate layer 160. For example, the intermediate layer 160 can include a first intermediate sub-layer and a second intermediate sub-layer, the acoustic velocity adjustment layer 170 is disposed on the side of the first intermediate sub-layer distal to the piezoelectric substrate 100; the second intermediate sub-layer is disposed on the side of the first intermediate sub-layer distal to the piezoelectric substrate, covers the surface of the first intermediate sub-layer distal to the piezoelectric substrate, and covers the sidewall of the acoustic velocity adjustment layer 170 and the surface of the acoustic velocity adjustment layer 170 distal to the piezoelectric substrate. In this embodiment, the surface of the acoustic velocity adjustment layer 170 proximal to the piezoelectric substrate, the surface of the acoustic velocity adjustment layer 170 distal to the piezoelectric substrate, and the sidewall of the acoustic velocity adjustment layer 170 are all covered by the intermediate layer 160 and in contact with the intermediate layer. In some embodiments, by embedding the acoustic velocity adjustment layer 170 in the intermediate layer 160, the thickness of the intermediate layer 160 in the region where the acoustic velocity adjustment layer is disposed can also be substantially thinned.

[0072] Referring to FIG. 3H, in some embodiments, the acoustic velocity adjustment layer 170 is disposed on the side of the intermediate layer 160 distal to the piezoelectric substrate, and no groove can be disposed in the intermediate layer 160, i.e., the acoustic velocity adjustment layer 170 is located on the top of the intermediate layer 160. The passivation layer 180 is disposed on the side of the intermediate layer 160 distal to the piezoelectric substrate, and can cover or not cover the acoustic velocity adjustment layer 170. For example, as shown in FIG. 3H, the passivation layer 180 covers the sidewall of the acoustic velocity adjustment layer 170 and the surface of the acoustic velocity adjustment layer 170 distal to the piezoelectric substrate. In some other examples, the passivation layer 180 can also have an opening similar to that shown in FIG. 2A to expose the acoustic velocity adjustment layer 170.

[0073] In various embodiments, the passivation layer covers the intermediate layer, so as to protect the intermediate layer; in examples where the acoustic velocity adjustment layer is not covered by the passivation layer, the acoustic velocity adjustment layer can also serve as a passivation layer, playing a protective role for the intermediate layer.

[0074] It should be understood that in the embodiments shown in FIGS. 3A-3H, the acoustic velocity adjustment layer 170 is disposed in the central region of the interdigital electrode region, only the position and / or thickness in the direction perpendicular to the main surface of the piezoelectric substrate, etc. are different.

[0075] In the embodiments of the present disclosure, the sound speed adjustment layer is arranged to change the sound speed of the central region, so that the sound speed difference is generated between the central region and the terminal region, thereby achieving the effect of suppressing the clutter. For example, during the operation of the SAW resonator structure, the SAW propagates along the arrangement direction (for example, the second direction D2) of the plurality of interdigital electrodes of the interdigital transducer 150, however, there may also be some transverse waves (i.e., spurious acoustic waves, or clutter) propagating along the extension direction (for example, the first direction D1) of the interdigital electrodes, and such clutter will cause energy loss, thereby reducing the performance of the resonator and the filter including the resonator; in the embodiments of the present disclosure, the sound speed adjustment layer is arranged to generate a region or interface with a sound wave propagation impedance change, and the sound speed of the region is changed (for example, increased), so that the sound speed difference is generated between the plurality of regions arranged in the first direction, thereby suppressing or reducing the clutter propagating in the first direction D1, avoiding or reducing the energy loss, and thereby improving the performance of the device.

[0076] In the embodiments shown in FIG. 2A and FIG. 3A to FIG. 3H, the sound speed adjustment layer is arranged in the central region of the interdigital electrode region, so that the propagation speed of the sound wave in the central region of the interdigital electrode is higher than the propagation speed of the sound wave in the terminal region of the interdigital electrode region, and the sound speed difference is generated between the central region and the terminal region, thereby suppressing the propagation of the transverse wave. In the embodiments of FIG. 2A, FIG. 3A to FIG. 3E and FIG. 3G, the sound speed adjustment layer 170 is at least partially embedded in the intermediate layer, for example, the sound speed adjustment layer 170 is arranged in the groove of the intermediate layer, or the sound speed adjustment layer 170 is entirely buried in the intermediate layer, so that the intermediate layer has a thinned thickness in the central region of the interdigital electrode region where the sound speed adjustment layer is arranged; in some embodiments, thinning the thickness of the portion of the intermediate layer located in the central region of the interdigital electrode can also be beneficial to increase the propagation speed of the sound wave in the central region of the interdigital electrode.

[0077] That is, in these embodiments, the sound speed adjustment layer 170 is arranged to increase the sound speed of the central region of the interdigital electrode, so that the sound speed difference is generated between the central region and the terminal region of the interdigital electrode region, thereby suppressing the transverse wave; in some embodiments, the thickness of the first portion of the intermediate layer located in the central region of the interdigital electrode region is thinned, which can further increase the sound speed of the central region, thereby further increasing the sound speed difference between the central region and the terminal region of the interdigital electrode region, thereby more effectively suppressing the transverse wave.

[0078] Referring back to FIGS. 1A and 1B, in some embodiments, the first bus bar 111 and the second bus bar 121 are located on opposite sides of the interdigital transducer region IR in the first direction D1, and can each extend along the second direction D2. The first bus bar 111 is connected with the plurality of first interdigital electrodes 110, and the second bus bar 121 is connected with the plurality of second interdigital electrodes 120. For example, the first bus bar 111 is located on one side of the plurality of interdigital electrodes 110 in the first direction D1, and is connected with the plurality of first interdigital electrodes 110, such that the plurality of first interdigital electrodes 110 are electrically connected with each other through the first bus bar 111. Similarly, the second bus bar 121 is located on one side of the plurality of second interdigital electrodes 120 in the first direction D1, and is connected with the plurality of interdigital electrodes 120, such that the plurality of second interdigital electrodes 120 are electrically connected with each other through the second bus bar 121. The first bus bar 111 and the plurality of first interdigital electrodes 110 collectively form a first interdigital electrode structure, and the second bus bar 121 and the plurality of second interdigital electrodes 120 collectively form a second interdigital electrode structure. The first interdigital electrode structure and the second interdigital electrode structure can each be monolithically formed.

[0079] For example, each portion of the first interdigital electrodes 110 and the first bus bar 111 are connected with each other and can be monolithically formed; each portion of the second interdigital electrodes 120 and the second bus bar 121 are connected with each other and can be monolithically formed. The plurality of interdigital electrodes and the plurality of bus bars of the interdigital transducer 150 can be disposed in the same layer.

[0080] In some embodiments, the surface acoustic wave resonator device further comprises a first reflector and a second reflector. The first reflector and the second reflector are disposed on the piezoelectric substrate and are arranged on opposite sides of the interdigital transducer in the second direction. In some embodiments, the orthogonal projection of the acoustic velocity adjustment layer on the piezoelectric substrate is offset from the orthogonal projection of the first reflector and the second reflector on the piezoelectric substrate; or, the orthogonal projection of the acoustic velocity adjustment layer on the piezoelectric substrate overlaps with the orthogonal projection of the first reflector and / or the second reflector on the piezoelectric substrate.

[0081] Referring to FIG. 1A, in some embodiments, the surface acoustic wave resonator device 500 further comprises a first reflector 151 and a second reflector 152. The first reflector 151 and the second reflector 152 can be disposed in the same layer as the interdigital transducer 150. That is, each component of the first reflector 151, the second reflector 152, and the interdigital transducer 150 can be formed from the same material layer through the same patterning process. For example, the first reflector, the second reflector, and the interdigital transducer can comprise a metal material, such as tungsten (W), platinum (Pt), gold (Au), copper (Cu), zinc (Zn), silver (Ag), molybdenum (Mo), or any combination thereof.

[0082] For example, the first reflective electrode 151 and the second reflective electrode 152 are disposed on opposite sides of the interdigital transducer 150 in the second direction D2, each of which includes a plurality of reflective electrodes 52 and a bus bar 53. For example, in each of the reflective electrodes, the plurality of reflective electrodes 52 extend substantially parallel to each other in the first direction D1 and are arranged at intervals in the second direction D2, and the bus bar 53 extends in the second direction D2 and is connected to the plurality of reflective electrodes 52. For example, the two bus bars 53 are located on opposite sides of the plurality of reflective electrodes 52 in the first direction D1 and can be substantially parallel to each other and each electrically connected to the plurality of reflective electrodes 52. The number of reflective electrodes 52 in the first reflective electrode 151 can be the same as or different from the number of reflective electrodes 52 in the second reflective electrode 152. It should be understood that the number of interdigital electrodes in the interdigital transducer and the number of reflective electrodes in the reflective electrode shown in the figure are only illustrative, and the present disclosure is not limited thereto.

[0083] In some embodiments, the acoustic velocity adjustment layer 170 is disposed in the central region of the interdigital electrode region without extending into the region where the reflective electrode is located. For example, the orthogonal projection of the acoustic velocity adjustment layer 170 on the piezoelectric substrate is offset from the orthogonal projection of the first reflective electrode and the second reflective electrode on the piezoelectric substrate. In other embodiments, the acoustic velocity adjustment layer 170 can also extend into the region where the reflective electrode is located.

[0084] In some embodiments, the surface acoustic wave resonator device further includes a first protruding structure disposed in the first end region and the second end region of the interdigital electrode region, the first protruding structure being configured to change the acoustic velocity of the first end region and the second end region. In some embodiments, the first protruding structure can be configured to reduce the acoustic velocity of the first end region and the second end region. In some embodiments, the orthogonal projection of the acoustic velocity adjustment layer on the piezoelectric substrate is offset from the orthogonal projection of the protruding structure on the piezoelectric substrate. For example, the first protruding structure can be disposed in the same layer as the interdigital transducer, or the first protruding structure is disposed on the side of the interdigital transducer away from the intermediate layer.

[0085] In some embodiments, the first protruding structure includes a plurality of first mass loading blocks, the plurality of first mass loading blocks being respectively disposed on the side away from the piezoelectric substrate of the end portion of the plurality of interdigital electrodes located in the first end region and the second end region. For example, the plurality of first mass loading blocks can be a plurality of metal blocks. For example, each first mass loading block overlaps the end portion of the corresponding one of the interdigital electrodes in a direction perpendicular to the main surface of the piezoelectric substrate and has a sidewall aligned in a direction perpendicular to the main surface of the piezoelectric substrate. In this embodiment, the first mass loading blocks of the first protruding structure protrude from the surface of the interdigital transducer (e.g., the central portion of the interdigital electrode) on the side away from the piezoelectric substrate in a direction perpendicular to the main surface of the piezoelectric substrate.

[0086] FIG. 4A shows a schematic plan view of a surface acoustic wave resonator device 600a according to some other embodiments of the present disclosure. FIG. 4B shows a schematic enlarged plan view of an interdigital transducer in the surface acoustic wave resonator device shown in FIG. 4A according to some other embodiments of the present disclosure. FIGS. 5A and 5B show schematic cross-sectional views of a surface acoustic wave resonator device according to some other embodiments of the present disclosure, and are cross-sectional views taken along lines A-A’ and B-B’ of FIG. 4A, respectively. The surface acoustic wave resonator device 600a is similar to the surface acoustic wave resonator device 500, except that the surface acoustic wave resonator device 600a further comprises first protruding structures disposed at the interdigital electrode end regions.

[0087] Referring to FIGS. 4A, 4B, 5A and 5B, in some embodiments, the first and second end regions E1 and E2 of the interdigital electrode region are further provided with first protruding structures 155, which can comprise a plurality of mass loading blocks respectively corresponding to (e.g., one-to-one corresponding to) the end portions (i.e., the first end portions and the second end portions) of the plurality of interdigital electrodes. The plurality of mass loading blocks respectively overlap the end portions of the plurality of interdigital electrodes in a direction perpendicular to the main surface of the piezoelectric substrate. For example, the plurality of mass loading blocks are respectively disposed on a side of the end portions of the plurality of interdigital electrodes away from the piezoelectric substrate, covering and contacting the surface of the side of the end portions of the plurality of interdigital electrodes away from the piezoelectric substrate.

[0088] For example, the first protruding structures 155 comprise a plurality of mass loading blocks 155a at the first end region E1 and a plurality of mass loading blocks 155b at the second end region E2, the plurality of mass loading blocks 155a are respectively disposed on a side of the first end portions 11 of the plurality of first interdigital electrodes 110 and the second end portions 22 of the plurality of second interdigital electrodes 120 away from the piezoelectric substrate 100, covering and contacting the surface of the side of the end portions of the plurality of interdigital electrodes away from the piezoelectric substrate 100. The plurality of mass loading blocks 155a are arranged in the second direction D2 and can be one-to-one corresponding to the plurality of end portions of the plurality of interdigital electrodes in the first end region E1; that is, each mass loading block 155a is disposed on one of the first end portions 11 of the first interdigital electrodes 110 and the second end portions 22 of the second interdigital electrodes 120, and there is one mass loading block 155a on each of the first end portions 11 of the first interdigital electrodes 110 and the second end portions 22 of the second interdigital electrodes 120.

[0089] The plurality of mass loading blocks 155b are respectively arranged on the side of the second end portions 12 of the plurality of first interdigital electrodes 110 and the first end portions 21 of the plurality of second interdigital electrodes 120 away from the piezoelectric substrate 100, covering and contacting the surfaces of the end portions of the plurality of interdigital electrodes away from the piezoelectric substrate 100. The plurality of mass loading blocks 155b are arranged in the second direction D2 in a spaced-apart manner, and can be arranged one-to-one corresponding to the plurality of end portions of the plurality of interdigital electrodes in the second end region E2; that is, each mass loading block 155b is arranged on one of the second end portions 12 of the first interdigital electrodes 110 and the first end portions 21 of the second interdigital electrodes 120, and one mass loading block 155b is arranged on each of the second end portions 12 of the first interdigital electrodes 110 and the first end portions 21 of the second interdigital electrodes 120. The mass loading blocks 155a and 155b can be collectively referred to as first mass loading blocks.

[0090] In some embodiments, in the corresponding arrangement of the mass loading blocks and the interdigital electrode end portions, the mass loading blocks and the corresponding interdigital electrode end portions overlap in a direction perpendicular to the main surface of the piezoelectric substrate, and can have side walls that are substantially aligned in the direction perpendicular to the main surface of the piezoelectric substrate. For example, the size (width, area, etc.) of the mass loading block can be substantially the same as the size of the corresponding interdigital electrode end portion; for example, the orthogonal projection of the mass loading block on the piezoelectric substrate can substantially coincide with the orthogonal projection of the corresponding interdigital electrode end portion on the piezoelectric substrate.

[0091] In some embodiments, the side of the first protruding structure 155 close to the piezoelectric substrate is in contact with the interdigital electrode end portion, and the side wall of the first protruding structure 155 and the side of the first protruding structure 155 away from the piezoelectric substrate are covered by and in contact with the intermediate layer 160.

[0092] In some embodiments, the orthogonal projection of the sound velocity adjustment layer 170 on the piezoelectric substrate can be adjacent to but not overlapping with the orthogonal projection of the plurality of mass loading blocks of the first protruding structure 155 on the piezoelectric substrate.

[0093] In this embodiment, the sound velocity adjustment layer 170 can also be arranged in the groove of the intermediate layer, arranged on the side of the passivation layer away from the intermediate layer, or buried in the intermediate layer.

[0094] FIGS. 5A and 6A-6H show various examples in which the sound velocity adjustment layer 170 is arranged in the central region of the interdigital electrode region, and the relative positional relationship and structural features between the sound velocity adjustment layer 170, the intermediate layer 160, and the passivation layer 180 shown in these figures are similar or substantially the same as those described above with reference to FIGS. 2A and 3A-3H, and will not be described again here.

[0095] In this embodiment, the sound velocity in the central region of the interdigital electrode can be increased by providing the sound velocity adjustment layer 170 in the central region of the interdigital electrode. In some embodiments, the thickness of the portion of the intermediate layer in the central region can be thinned, thereby further increasing the sound velocity in the central region of the interdigital electrode. Moreover, the first protruding structure including a plurality of mass loading blocks provided in the terminal regions can decrease the sound velocity in the first terminal region and the second terminal region, thereby further increasing the sound velocity difference between the central region and the terminal regions, which can be more conducive to suppressing spurious signals.

[0096] In some embodiments, the protruding structure is provided in the terminal regions of the interdigital electrode but not in the regions where the reflectors are located. In alternative embodiments, the protruding structure can also be provided in the regions where the reflectors are located.

[0097] For example, the surface acoustic wave resonator device further includes a second protruding structure provided in the extended regions of the first terminal region and the second terminal region of the interdigital electrode region in the second direction, and the second protruding structure includes a portion of the first reflector and / or the second reflector, or the second protruding structure overlaps the first reflector and / or the second reflector in the orthographic projection on the piezoelectric substrate.

[0098] In some embodiments, the second protruding structure includes a plurality of second mass loading blocks provided on the side of the plurality of reflective electrodes of the first reflector and the second reflector away from the piezoelectric substrate and in the extended regions of the first terminal region and the second terminal region in the second direction.

[0099] FIG. 7A shows a schematic plan view of a surface acoustic wave resonator device 600b according to some alternative embodiments of the present disclosure. FIG. 7B shows a schematic cross-sectional view of the surface acoustic wave resonator device 600b taken along line B-B’ of FIG. 7A according to some alternative embodiments of the present disclosure. The surface acoustic wave resonator device 600b is similar to the surface acoustic wave resonator device 600a of the above-described embodiments, except that the surface acoustic wave resonator device 600b further includes a second protruding structure 155’ provided on the reflectors.

[0100] Referring to FIGS. 7A and 7B, in some embodiments, the second protruding structure 155’ includes a plurality of mass loading blocks 155c and 155d overlapping the reflective electrodes of the reflectors. The mass loading blocks 155c and 155d can be or include metal blocks. The plurality of mass loading blocks 155c and 155d can be collectively referred to as second mass loading blocks.

[0101] For example, the plurality of mass load blocks 155c are disposed in a region corresponding to the first end region El of the interdigital electrode region (i.e., a region in which the first end region El extends in the second direction D2), and are disposed on a side of the plurality of reflective electrodes 52 of the first reflective comb 151 and the second reflective comb 152 distal to the piezoelectric substrate 100, covering and contacting a surface of the plurality of reflective electrodes 52 on the side distal to the piezoelectric substrate. The plurality of mass load blocks 155c and the plurality of mass load blocks 155a are arranged at intervals in the second direction D2, and can be substantially aligned with each other in the second direction D2. For example, the plurality of mass load blocks 155c can be disposed one-to-one with the plurality of reflective electrodes 52 of the first reflective comb 151 and the second reflective comb 152. Each mass load block 155c is disposed on a corresponding one of the reflective electrodes 52, i.e., overlaps the reflective electrode 52 in a direction perpendicular to the main surface of the piezoelectric substrate. For example, for a mass load block 155c and a reflective electrode 52 that overlap each other, the mass load block 155c can have a side wall that is substantially aligned with the reflective electrode 52 in a direction perpendicular to the main surface of the piezoelectric substrate; the width of the mass load block 155c in the second direction D2 can be substantially equal to the width of the reflective electrode 52 in the second direction D2.

[0102] For example, the plurality of mass load blocks 155d are disposed in a region corresponding to the second end region E2 of the interdigital electrode region (i.e., a region in which the second end region E2 extends in the second direction D2), and are disposed on a side of the plurality of reflective electrodes 52 of the first reflective comb 151 and the second reflective comb 152 distal to the piezoelectric substrate 100, covering and contacting a surface of the plurality of reflective electrodes 52 on the side distal to the piezoelectric substrate. The plurality of mass load blocks 155d and the plurality of mass load blocks 155b are arranged at intervals in the second direction D2, and can be substantially aligned with each other in the second direction D2. For example, the plurality of mass load blocks 155d can be disposed one-to-one with the plurality of reflective electrodes 52 of the first reflective comb 151 and the second reflective comb 152. Each mass load block 155d is disposed on a corresponding one of the reflective electrodes 52, i.e., overlaps the reflective electrode 52 in a direction perpendicular to the main surface of the piezoelectric substrate. For example, for a mass load block 155d and a reflective electrode 52 that overlap each other, the mass load block 155d can have a side wall that is substantially aligned with the reflective electrode 52 in a direction perpendicular to the main surface of the piezoelectric substrate; the width of the mass load block 155d in the second direction D2 can be substantially equal to the width of the reflective electrode 52 in the second direction D2.

[0103] In some embodiments, the first protruding structure 155 and the second protruding structure 155' are disposed in the same layer, and can be formed by patterning the same layer of material. The plurality of mass load blocks of the first protruding structure 155 and the second protruding structure 155' can comprise a metal material, and the metal material can be the same as or different from the metal material included in the IDT and the reflector. For example, the mass load blocks can comprise a metal material such as tungsten (W), platinum (Pt), gold (Au), copper (Cu), zinc (Zn), silver (Ag), molybdenum (Mo), or any combination thereof.

[0104] The surfaces of the first protruding structure and the second protruding structure that are proximal to the piezoelectric substrate are in contact with the IDT terminal portions and the reflector, respectively, and the sidewalls of the first protruding structure and the second protruding structure and the surfaces thereof that are distal to the piezoelectric substrate are covered by and in contact with the intermediate layer 160.

[0105] The cross-sectional view of the SAW resonator device 600b taken along line A-A' of FIG. 7A is substantially the same as the cross-sectional view of the SAW resonator device 600a taken along line A-A' of FIG. 4A, and can have the structure shown in any one of FIGS. 5A, 6A-6H, and reference can be made to the above description with respect to FIGS. 5A, 6A-6H, which will not be repeated here.

[0106] In other embodiments, the first protruding structure is disposed in the same layer as the IDT, and comprises a plurality of terminal portions of the IDT electrodes located in the first terminal region and the second terminal region; the terminal portions of the plurality of IDT electrodes (i.e., the first terminal portions and the second terminal portions) each have a second width in the second direction, the portions of the plurality of IDT electrodes located in the central region (i.e., the central portions) each have a first width in the second direction, and the second width is greater than the first width. That is, the terminal portions of the plurality of IDT electrodes each protrude in the second direction from the central portions of the plurality of IDT electrodes.

[0107] FIG. 8A shows a schematic plan view of a SAW resonator device 700a according to other embodiments of the present disclosure. FIG. 8B shows a schematic enlarged plan view of an IDT in the SAW resonator device shown in FIG. 8A according to other embodiments of the present disclosure. FIGS. 9A and 9B show schematic cross-sectional views of a SAW resonator device according to other embodiments of the present disclosure, and are cross-sectional views taken along lines A-A' and B-B' of FIG. 8A, respectively. FIGS. 10A-10H show cross-sectional views of a SAW resonator device taken along line A-A' of FIG. 8A according to some alternative embodiments. The SAW resonator device 700a is similar to the SAW resonator devices of the foregoing embodiments, except that the SAW resonator device 700a further comprises a first protruding structure disposed in the terminal region of the IDT region, and the first protruding structure is disposed in the same layer as the IDT.

[0108] Referring to FIGS. 8A, 8B, 9A, and 9B, in some embodiments, the center portions 10 of the first interdigital electrodes 110 and the center portions 20 of the second interdigital electrodes 120 each have a first width W1 in the second direction D2. The first end portions 11 and the second end portions 12 of the first interdigital electrodes 110 and the first end portions 21 and the second end portions 22 of the second interdigital electrodes 120 each have a second width W2 in the second direction D2, and the second width W2 is greater than the first width W1. For example, the first width W1 of the center portion of each interdigital electrode can be substantially the same as each other, and the second width W2 of the end portion of each interdigital electrode can be substantially the same as each other.

[0109] The end portions of the plurality of interdigital electrodes having the greater width (i.e., the first end portions and the second end portions of the first interdigital electrodes and the first end portions and the second end portions of the second interdigital electrodes) collectively constitute a first protruding structure 255 at the interdigital electrode end region. That is, the first protruding structure 255 includes the end portions of the plurality of interdigital electrodes. In this embodiment, the first protruding structure 255 protrudes beyond the edges of the center portions of the interdigital electrodes in a direction parallel to the major surface of the piezoelectric substrate (e.g., the second direction D2). In some embodiments, the first protruding structure constituted by the end portions of the interdigital electrodes having the greater width can be referred to as a hammer head structure; by providing such a hammer head structure, it is also possible to advantageously reduce the acoustic velocity at the interdigital electrode end region, thereby achieving the effect of suppressing spurious waves.

[0110] The surface acoustic wave resonator device 700a also includes the acoustic velocity adjustment layer 170 disposed at the center region of the interdigital electrode. For example, the orthogonal projection of the acoustic velocity adjustment layer 170 on the piezoelectric substrate can be offset from (e.g., abut but not overlap) the orthogonal projection of the first protruding structure 255 (i.e., the end portions of the plurality of interdigital electrodes) on the piezoelectric substrate.

[0111] In this embodiment, the acoustic velocity adjustment layer 170 can also be disposed in the recess of the intermediate layer, disposed on the side of the passivation layer distal to the intermediate layer, or buried in the intermediate layer.

[0112] FIGS. 9A and 10A-10H show various examples in which the acoustic velocity adjustment layer 170 is disposed at the center region of the interdigital electrode region, and the relative positional relationships and structural features between the acoustic velocity adjustment layer 170, the intermediate layer 160, and the passivation layer 180 shown in these figures are similar or substantially the same as those described above with reference to FIGS. 2A and 3A-3H, and thus will not be described again here.

[0113] In this embodiment, the sound velocity of the center region of the interdigital electrode region can be accelerated by disposing the sound velocity adjustment layer in the center region of the interdigital electrode region, so that the sound velocities of the center region and the end regions of the interdigital electrode have a difference; in some embodiments, the thickness of the portion of the intermediate layer located in the center region can be thinned to further accelerate the sound velocity of the center region of the interdigital electrode; and the first protruding structure composed of the end portion of the interdigital electrode with a larger width disposed in the end region can reduce the sound velocity of the first end region and the second end region, so as to further increase the sound velocity difference between the center region and the end regions, thereby more favorably suppressing the spurious waves.

[0114] Referring to FIG. 8A, in some embodiments, the hammerhead structure as the first protruding structure is disposed in the end region of the interdigital electrode region, and can not be disposed in the region where the reflection grating is located; for example, the width of each portion of each reflection electrode 52 of the first reflection grating 151 and the second reflection grating 152 in the second direction D2 is substantially the same. For example, the width of the portion of the reflection electrode 52 located in the extended region of the center region of the interdigital electrode in the second direction can be substantially equal to the width of the portion of the reflection electrode 52 located in the extended region of the end region of the interdigital electrode in the second direction.

[0115] In other embodiments, the reflection electrodes of the first reflection grating and / or the second reflection grating can also be provided with a second protruding structure similar to the hammerhead structure of the interdigital electrode. For example, in the plurality of reflection electrodes of the first reflection grating and / or the second reflection grating, each reflection electrode includes a first electrode portion, a second electrode portion and a third electrode portion located in the extended region of the center region, the first end region and the second end region of the interdigital electrode region in the second direction respectively; the width of the second electrode portion and the third electrode portion in the second direction is greater than the width of the first electrode portion in the second direction, and the second protruding structure includes the second electrode portions and the third electrode portions of the plurality of reflection electrodes.

[0116] FIG. 11A shows a schematic top view of a surface acoustic wave resonator device 700b according to some alternative embodiments of the present disclosure. FIG. 11B shows a schematic cross-sectional view of the surface acoustic wave resonator device 700b taken along line B-B’ of FIG. 11A according to some alternative embodiments of the present disclosure. The surface acoustic wave resonator device 700b is similar to the surface acoustic wave resonator device 700a, with the difference that in the surface acoustic wave resonator device 700b, a second protruding structure located in the reflection grating is further included.

[0117] Referring to FIGS. 11A and 11B, in some embodiments, in the first and second reflective gratings 151 and 152, each reflective electrode 52 can include a first electrode portion 52a, a second electrode portion 52b, and a third electrode portion 52c. The first electrode portion 52a is located in a region corresponding to the interdigital electrode central region, and the second and third electrode portions 52b and 52c are located in regions corresponding to the interdigital electrode end regions. The first electrode portion 52a has a first reflective electrode width W10 in the second direction D2, the second and third electrode portions 52b and 52c each have a second reflective electrode width W20 in the second direction D2, and the second reflective electrode width W20 is greater than the first reflective electrode width W10. The widths of the second and third electrode portions 52b and 52c can be substantially the same.

[0118] For example, the plurality of first electrode portions 52a of the first and second reflective gratings are located in an extended region of the interdigital electrode central region in the second direction, and are substantially aligned with the central portions of the plurality of interdigital electrodes in the second direction. The plurality of second electrode portions 52b of the first and second reflective gratings are located in an extended region of the first end region E1 of the interdigital electrode region in the second direction D2, and are arranged in the second direction D2 in a spaced-apart manner with the first end portions 11 of the first interdigital electrodes 110 and the second end portions 22 of the second interdigital electrodes 120 and are substantially aligned with each other. The plurality of third electrode portions 52c of the first and second reflective gratings are located in an extended region of the second end region E2 of the interdigital electrode region in the second direction D2, and are arranged in the second direction D2 in a spaced-apart manner with the second end portions 12 of the first interdigital electrodes 110 and the first end portions 21 of the second interdigital electrodes 120 and are substantially aligned with each other.

[0119] In this embodiment, the second and third electrode portions 52b and 52c of the plurality of reflective electrodes of the reflective gratings collectively form a second protruding structure 255’ that protrudes in a direction parallel to the main surface of the piezoelectric substrate (e.g., the second direction D2) from the first electrode portions 52a and the like of the reflective electrodes. The second protruding structure 255’ can also be referred to as a hammerhead structure. By providing the hammerhead structure in the region where the reflective gratings are located, it is also possible to advantageously suppress transverse waves.

[0120] In some embodiments, the acoustic velocity adjustment layer 170 is disposed in the central region of the interdigital electrode region without extending into the regions where the first or second reflective gratings are located. That is, the orthogonal projection of the first reflective grating 151 and the second reflective grating 152 on the piezoelectric substrate can be offset from the orthogonal projection of the acoustic velocity adjustment layer 170 on the piezoelectric substrate, and the orthogonal projection of the second protruding structure 255’ on the piezoelectric substrate 100 can not be contiguous with the orthogonal projection of the acoustic velocity adjustment layer 170 on the piezoelectric substrate, but the present disclosure is not limited thereto. In alternative embodiments, the acoustic velocity adjustment layer 170 can also extend into the regions where the first reflective grating and / or the second reflective grating are located, and overlap with one or more reflective electrodes in the direction perpendicular to the main surface of the piezoelectric substrate; the orthogonal projection of the acoustic velocity adjustment layer 170 on the piezoelectric substrate can also be contiguous with the orthogonal projection of the second protruding structure 255’ on the piezoelectric substrate 100.

[0121] In this embodiment, the cross-sectional structure of the SAW resonator device 700b taken along line A-A’ of FIG. 11A can be similar or substantially the same as the cross-sectional structure of the SAW resonator device 700a taken along line A-A’ of FIG. 8A, and can have the structure shown in any one of FIGS. 9A, 10A-10H, and specific reference can be made to the descriptions made above with respect to these figures, which will not be repeated here.

[0122] FIG. 12A shows a schematic plan view of a SAW resonator device 800a according to some other embodiments of the present disclosure. FIG. 12B shows a schematic enlarged plan view of an interdigital transducer in the SAW resonator device shown in FIG. 12A according to some other embodiments of the present disclosure. FIGS. 13A and 13B show schematic cross-sectional views of a SAW resonator device according to some other embodiments of the present disclosure, and are cross-sectional views taken along lines A-A’ and B-B’ of FIG. 12A, respectively. FIGS. 14A-14H show cross-sectional views of a SAW resonator device taken along line A-A’ of FIG. 12A according to some alternative embodiments of the present disclosure. The SAW resonator device 800a is similar to the SAW resonator devices of the foregoing embodiments, except that the SAW resonator device 800a further includes additional bus bars disposed in the peripheral region of the interdigital electrode.

[0123] In some embodiments, the SAW resonator device further comprises a first additional bus bar and a second additional bus bar, the first additional bus bar is located in the first perimeter region, extends along the second direction, and is connected with the first IDT; the second additional bus bar is located in the second perimeter region, extends along the second direction, and is connected with the second IDT. In this embodiment, the first bus bar, the first additional bus bar, and the plurality of first IDTs are connected with each other to form a first IDT structure. For example, the first bus bar, the first additional bus bar, and the plurality of first IDTs can be disposed in the same layer and can be integrally formed. The second bus bar, the second additional bus bar, and the plurality of second IDTs are connected with each other to form a second IDT structure. For example, the second bus bar, the second additional bus bar, and the plurality of second IDTs can be disposed in the same layer and can be integrally formed.

[0124] Referring to FIGS. 12A and 12B, in some embodiments, the IDT 150 of the SAW resonator device 800a can further comprise a first additional bus bar 112 and a second additional bus bar 122. The first additional bus bar 112 is located in the first perimeter region R1, extends along the second direction D2, and is connected with the plurality of first IDTs 110; for example, the first additional bus bar 112 is located between the first bus bar 111 and the end portion of the plurality of IDTs in the first direction D1, and is connected with the connection portion 13 of the plurality of first IDTs 110. The second additional bus bar 122 is located in the second perimeter region R2, extends along the second direction D2, and is connected with the plurality of second IDTs 120; for example, the second additional bus bar 122 is located between the second bus bar 121 and the end portion of the plurality of IDTs in the first direction D1, and is connected with the connection portion 23 of the plurality of second IDTs 120. The first additional bus bar 112 and the second IDT structure are electrically isolated, and the second additional bus bar 122 and the first IDT structure are electrically isolated.

[0125] In some embodiments, the width of the first additional bus bar 112 in the first direction D1 can be smaller than the width of the first bus bar 111 in the first direction D1; the width of the second additional bus bar 112 in the first direction D1 can be smaller than the width of the second bus bar 121 in the first direction D1. The first additional bus bar 112 and the first bus bar 111 can be disposed side by side in the first direction D1; the second additional bus bar 122 and the second bus bar 121 can be disposed side by side in the first direction D1.

[0126] In this embodiment, by disposing the additional bus bar in the perimeter region, the sound speed in the region where the additional bus bar is disposed can be changed (for example, reduced), thereby causing a sound speed difference between different regions, thereby playing a role of spurious wave suppression.

[0127] Similar to the foregoing embodiments, the sound velocity adjustment layer 170 can be provided in the central region of the interdigital electrode region; in addition, a first protruding structure can be provided in the end region of the interdigital electrode region, for example, as shown in FIGS. 12A and 12B, the end portions of the plurality of interdigital electrodes can be provided to have a larger width, thereby forming a hammerhead structure as the first protruding structure; or, the first protruding structure can be provided to include a plurality of mass loading blocks on the end portions of the interdigital electrodes (as shown in FIGS. 4A and 4B); or, the first protruding structure in the end region of the interdigital electrode can be omitted. For example, the interdigital electrode peripheral region of any one of the foregoing embodiments of the surface acoustic wave resonator device 500, 600a, 600b, 700a, 700b can be further provided with an additional bus bar to further improve the spurious suppression capability of the resonator device.

[0128] In this embodiment, the cross-sectional structure of the surface acoustic wave resonator device 800a shown in FIG. 13A taken along the line A-A’ of FIG. 12A can be similar to the cross-sectional view of the surface acoustic wave resonator device 700a shown in FIG. 9A taken along the line A-A’ of FIG. 8A, except that the cross-sectional view shown in FIG. 13A further includes a second additional bus bar 122 provided between the end of the first interdigital electrode and the second bus bar. The cross-sectional structure of the surface acoustic wave resonator device 800a shown in FIG. 13B taken along the line B-B’ of FIG. 12A can be substantially the same as the cross-sectional view of the surface acoustic wave resonator device 700a shown in FIG. 9B taken along the line B-B’ of FIG. 8A, and thus will not be described here.

[0129] In this embodiment, the sound velocity adjustment layer 170 can also be provided in the groove of the intermediate layer, on the side of the passivation layer away from the intermediate layer, or buried in the intermediate layer.

[0130] FIGS. 13A and 14A to 14H show various examples in which the sound velocity adjustment layer 170 is provided in the central region of the interdigital electrode region, and the relative positional relationship and structural features among the sound velocity adjustment layer 170, the intermediate layer 160, and the passivation layer 180 shown in these figures are similar or substantially the same as those described with reference to FIGS. 2A and 3A to 3H in the foregoing embodiments, and thus will not be described here.

[0131] In this embodiment, the sound velocity of the center region of the interdigital electrode can be increased by disposing the sound velocity adjustment layer in the center region of the interdigital electrode, so that the sound velocities of the center region and the end regions of the interdigital electrode are different; in some embodiments, the sound velocity of the center region of the interdigital electrode can be further increased by thinning the thickness of the portion of the intermediate layer located in the center region; and the sound velocities of the first end region and the second end region can be reduced by disposing the first protruding structure composed of the end portion of the interdigital electrode with a larger width in the end region, so that the sound velocity difference between the center region and the end regions can be further increased, thereby more favorably suppressing spurious waves. In addition, the sound velocities of the first peripheral region and the second peripheral region can also be changed by disposing the additional bus bars in the regions, thereby introducing more sound velocity changing regions, so that the regions have sound velocity differences with other regions of the interdigital electrode, thereby more favorably suppressing spurious waves.

[0132] FIG. 15A shows a schematic top view of a surface acoustic wave resonator device 800b according to some alternative embodiments of the present disclosure. FIG. 15B shows a schematic cross-sectional view of the surface acoustic wave resonator device 800b taken along line B-B’ of FIG. 15A according to some alternative embodiments of the present disclosure. The surface acoustic wave resonator device 800b is similar to the surface acoustic wave resonator device 800a, except that in the surface acoustic wave resonator device 800b, a second protruding structure 255’ is further disposed in the region where the reflector grating is located. The related structural features of the second protruding structure 255’ in the surface acoustic wave resonator device 800b are substantially the same as those of the second protruding structure 255’ in the surface acoustic wave resonator device 700b shown in FIG. 11A, and the cross-sectional structure shown in FIG. 15B is substantially the same as that shown in FIG. 11B, and thus will not be described here again.

[0133] In this embodiment, the cross-sectional structure of the surface acoustic wave resonator device 800b taken along line A-A’ of FIG. 15A shown in FIG. 15B can be similar to or substantially the same as the cross-sectional view of the surface acoustic wave resonator device 800a taken along line A-A’ of FIG. 12A shown in FIG. 13B, and can have the structure shown in any one of FIGS. 13A, 14A-14H, and thus reference can be made to the description of the foregoing figures, and thus will not be described here again.

[0134] FIG. 16 shows a schematic plan view of a surface acoustic wave resonator device 900 according to some other embodiments of the present disclosure. The surface acoustic wave resonator device 900 is similar to the surface acoustic wave resonator device 500 of the foregoing embodiments, except that in the surface acoustic wave resonator device 900, the sound velocity adjustment layer 170 further extends into the region where the reflector grating is located.

[0135] In some embodiments, the orthogonal projection of the sound velocity adjustment layer on the piezoelectric substrate can overlap with the orthogonal projection of the first reflector grating and / or the second reflector grating (e.g., one or more reflector electrodes) on the piezoelectric substrate.

[0136] Referring to FIG. 16, for example, the acoustic velocity adjustment layer 170 extends beyond the interdigital electrode region IR in the second direction D2, and can extend into the region where the first reflective grating 151 and the second reflective grating 152 are located, and overlap the plurality of reflective electrodes 52 in a direction perpendicular to the major surface of the piezoelectric substrate. For example, the orthogonal projection of the plurality of reflective electrodes 52 on the piezoelectric substrate can also be located within the orthogonal projection of the acoustic velocity adjustment layer 170 on the piezoelectric substrate. For example, the extended portion of the acoustic velocity adjustment layer 170 can be located in the extended region of the interdigital electrode center region in the second direction D2, and can overlap the first electrode portion of one or more reflective electrodes in a direction perpendicular to the major surface of the piezoelectric substrate; the first electrode portion of the one or more reflective electrodes overlaps and is substantially aligned with the central portion of the plurality of interdigital electrodes in the second direction D2.

[0137] The embodiment shown in FIG. 16 is a variation of the surface acoustic wave resonator device 500 to schematically show an example in which the acoustic velocity adjustment layer 170 extends to the region where the reflective gratings are located. It should be understood that in the surface acoustic wave resonator devices 600a, 600b, 700a, 700b, 800a, 800b of other embodiments, the acoustic velocity adjustment layer 170 can also further extend into the region where the first reflective grating and / or the second reflective grating are located.

[0138] The embodiments of the present disclosure provide a method of manufacturing a surface acoustic wave resonator device, wherein the surface acoustic wave resonator device has an interdigital electrode region including, in a first direction, a first peripheral region, a first end region, a center region, a second end region, and a second peripheral region arranged in sequence, and the method of manufacturing includes: providing a piezoelectric substrate; forming an interdigital transducer on the piezoelectric substrate, the interdigital transducer including a plurality of interdigital electrodes located in the interdigital electrode region and including a first interdigital electrode and a second interdigital electrode; the first interdigital electrode and the second interdigital electrode extend in the first direction and are alternately arranged in a second direction intersecting the first direction; the first interdigital electrode extends from the first peripheral region to the second end region, and the second interdigital electrode extends from the second peripheral region to the first end region; forming an intermediate layer on the piezoelectric substrate to cover the interdigital transducer; forming an acoustic velocity adjustment layer on at least a portion of a side of the intermediate layer away from the piezoelectric substrate; and forming a passivation layer on a side of the intermediate layer away from the piezoelectric substrate, wherein the acoustic velocity adjustment layer is located in the center region and overlaps a portion of the plurality of interdigital electrodes located in the center region in a direction perpendicular to the major surface of the piezoelectric substrate, and is configured to change the acoustic velocity of the center region.

[0139] For example, a piezoelectric substrate 100 can be provided, which can include a suitable piezoelectric material such as a piezoelectric crystal, a piezoelectric ceramic, etc. For example, the material of the piezoelectric substrate 100 can be aluminum nitride (AIN), doped aluminum nitride, zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNb03), quartz, potassium niobate (KNb03), lithium tantalate (LiTa03), an analog thereof, or a combination thereof. In some embodiments, the piezoelectric substrate 100 can be a single-layer structure or a multi-layer structure, such as a piezoelectric thin film composite structure, for example, a lithium tantalate piezoelectric thin film / silicon dioxide / silicon substrate composite structure. However, the present disclosure is not limited thereto.

[0140] In some embodiments, forming the interdigital transducer 150 on the piezoelectric substrate 100 can include forming a metal material layer on the piezoelectric substrate, and then performing a patterning process on the metal material layer to form a first metal layer including the interdigital transducer. In some embodiments, the first reflective grating 151 and the second reflective grating 152 are disposed in the same layer as the interdigital transducer 150, and can be formed by the same patterning process. For example, the patterning process on the metal material layer also forms the first reflective grating and the second reflective grating. That is, the interdigital transducer, the first reflective grating, and the second reflective grating are all disposed in the first metal layer. When the interdigital transducer 150 includes a hammerhead structure as the first protruding structure and / or the first reflective grating 151, the second reflective grating 152 includes a hammerhead structure as the second protruding structure, the hammerhead structure is also formed by the patterning process.

[0141] In some embodiments, when the interdigital transducer 150 includes a mass loading block as the first protruding structure and / or the first reflective grating 151, the second reflective grating 152 includes a mass loading block as the second protruding structure, the mass loading blocks can be formed by the following process: after forming the first metal layer described above, forming a mass loading material layer on the piezoelectric substrate and the first metal layer, which can be or include a metal material layer, for example; and then performing a patterning process on the mass loading material layer to form the mass loading blocks (e.g., metal blocks).

[0142] Subsequently, an intermediate layer 106 is formed on the piezoelectric substrate 100 to cover the first metal layer including the interdigital transducer and the reflective gratings, and also cover the mass loading blocks in embodiments having the mass loading blocks. For example, the intermediate layer can be formed by a deposition process; and the intermediate layer can be further subjected to a planarization process (e.g., a chemical mechanical polishing process) to have a substantially planar surface. The intermediate layer 106 at least includes a temperature compensation layer (e.g., a silicon oxide layer), or can also include a protective layer (e.g., a non-silicon oxide layer) located on the side of the temperature compensation layer close to the piezoelectric substrate.

[0143] In some embodiments, forming the acoustic velocity adjustment layer on a side of at least a portion of the intermediate layer distal to the piezoelectric substrate comprises: performing an etching process on the intermediate layer to remove a portion of the intermediate layer located in the central region to form a recess in the intermediate layer; and forming the acoustic velocity adjustment layer in the recess of the intermediate layer.

[0144] For example, as shown in FIG. 2A, FIG. 3A-3E, an etching process can be performed on the intermediate layer 160 to remove a portion of the intermediate layer 160 and form a recess 161. It should be understood that the recess 161 of the intermediate layer 160 corresponds to the location of the subsequently formed acoustic velocity adjustment layer. For example, the acoustic velocity adjustment layer is formed in the central region, and the recess 161 is correspondingly formed in the central region. For example, in the example where the acoustic velocity adjustment layer extends to the area where the reflective grating is located, the recess 161 can also be correspondingly formed in the area where the reflective grating is located. It should be understood that the recess 161 is formed in the temperature compensation layer of the intermediate layer, for example, at the top of the temperature compensation layer, and there is still sufficient temperature compensation material between the bottom of the recess and the interdigital transducer to meet the temperature compensation function of the resonator. That is, the temperature compensation layer is provided between the subsequently formed acoustic velocity adjustment layer and the interdigital transducer.

[0145] In some embodiments, the acoustic velocity adjustment layer 170 is formed in the recess 161 of the intermediate layer 160, wherein the thickness of the acoustic velocity adjustment layer 170 can be formed to be greater than, substantially equal to, or less than the depth of the recess 161.

[0146] In other embodiments, the step of forming the recess can also be omitted, for example, as shown in FIG. 3H, after the intermediate layer 160 is formed, the acoustic velocity adjustment layer 170 can be directly formed on the intermediate layer 160.

[0147] In some embodiments, forming the passivation layer comprises: forming the passivation layer in a region other than the central region, so that the passivation layer exposes the acoustic velocity adjustment layer; or the passivation layer is also formed in the central region to cover the surface of the acoustic velocity adjustment layer distal to the piezoelectric substrate.

[0148] For example, as shown in FIG. 2A, FIG. 3A and FIG. 3B, the passivation layer 180 is formed on the side of the intermediate layer 160 distal to the piezoelectric substrate, and the passivation layer 180 is formed in a region other than the recess 161 (for example, a region other than the central region), so that the passivation layer 180 exposes the acoustic velocity adjustment layer 170. That is, the surface of the acoustic velocity adjustment layer 170 distal to the piezoelectric substrate can not be covered by the passivation layer 180.

[0149] For example, as shown in FIG. 3C-3E, the passivation layer 180 can also be formed in the central region and cover the surface of the acoustic velocity adjustment layer 170 distal to the piezoelectric substrate.

[0150] In some embodiments, the sound velocity adjusting layer is formed on a side of the passivation layer distal to the piezoelectric substrate after the passivation layer is formed on a side of the intermediate layer distal to the piezoelectric substrate.

[0151] For example, as shown in FIG. 3F, after the intermediate layer 160 is formed, the passivation layer 180 is first formed on a side of the intermediate layer 160 distal to the piezoelectric substrate 100, and then the sound velocity adjusting layer 170 is formed on a side of the passivation layer 180 distal to the piezoelectric substrate 100.

[0152] In some embodiments, the intermediate layer includes a first intermediate sub-layer and a second intermediate sub-layer, and forming the intermediate layer and the sound velocity adjusting layer includes: after the first intermediate sub-layer is formed, forming the sound velocity adjusting layer on a side of the first intermediate sub-layer distal to the piezoelectric substrate; and after the sound velocity adjusting layer is formed, forming the second intermediate sub-layer on a side of the first intermediate sub-layer distal to the piezoelectric substrate to cover the first intermediate sub-layer and the sound velocity adjusting layer.

[0153] For example, as shown in FIG. 3G, forming the intermediate layer 160 can include forming a first intermediate sub-layer and a second intermediate sub-layer, the sound velocity adjusting layer 170 is formed on a side of the first intermediate sub-layer distal to the piezoelectric substrate, and the second intermediate sub-layer is formed on the first intermediate sub-layer and the sound velocity adjusting layer 170 to cover the side wall of the sound velocity adjusting layer 170 and the surface of the side of the sound velocity adjusting layer 170 distal to the piezoelectric substrate. There can be an interface between the first intermediate sub-layer and the second intermediate sub-layer, which is not specifically shown in the figure. The first intermediate sub-layer and the second intermediate sub-layer collectively constitute the intermediate layer 160, and the sound velocity adjusting layer 170 is buried in the intermediate layer 160.

[0154] The embodiments of the present disclosure provide a filter, which includes the surface acoustic wave resonator of any of the above embodiments.

[0155] In the surface acoustic wave resonator device, the manufacturing method thereof and the filter according to the embodiments of the present disclosure, the sound velocity adjustment layer is arranged in the center region of the interdigital electrode to change (for example, accelerate) the sound velocity of the center region, so that the sound velocity difference is formed between the center region and the end region, for example, the sound velocity of the center region is higher than that of the first end region and the second end region, thereby achieving the effect of suppressing spurious waves. In some embodiments, the sound velocity adjustment layer is arranged in the groove of the intermediate layer. Forming the groove in the intermediate layer can thin the thickness of the intermediate layer, thereby also facilitating the acceleration of the sound velocity of the region, further increasing the sound velocity difference between different regions (for example, the center region and the end region) of the interdigital electrode, and more facilitating the suppression of spurious waves. In some embodiments, the protruding structure (for example, a hammer head structure or a mass load block) arranged in the end region of the interdigital electrode and / or the extended region thereof can reduce the sound velocity of the region, thereby further increasing the sound velocity difference between the center region and the end region, and further improving the ability of the resonator to suppress spurious waves. In some embodiments, the additional bus bar arranged in the peripheral region of the interdigital electrode can introduce the region with changed (for example, reduced) sound velocity in the peripheral region, thereby more facilitating the suppression of spurious waves. Therefore, the present disclosure can effectively suppress spurious waves, reduce energy loss, and further improve the quality factor and performance of the resonator device and the filter comprising the same by the above arrangement.

[0156] The following points need to be explained:

[0157] (1) In the drawings of the embodiments of the present disclosure, only the structures related to the embodiments of the present disclosure are involved, and other structures can be referred to the general design.

[0158] (2) The features in the same embodiment and different embodiments of the present disclosure can be combined with each other without conflict.

[0159] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present disclosure, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A surface acoustic wave resonator device having an interdigital electrode region including, in order in a first direction, a first peripheral region, a first end region, a center region, a second end region, and a second peripheral region, the surface acoustic wave resonator device comprising: a piezoelectric substrate; an interdigital transducer disposed on the piezoelectric substrate and including a plurality of interdigital electrodes located in the interdigital electrode region and including a first interdigital electrode and a second interdigital electrode; the first and second interdigital electrodes extending along the first direction and alternatingly arranged along a second direction intersecting the first direction; the first interdigital electrode extending from the first peripheral region to the second end region, the second interdigital electrode extending from the second peripheral region to the first end region; an intermediate layer disposed on the piezoelectric substrate and covering the interdigital transducer; a sound velocity adjustment layer disposed on a side of at least a portion of the intermediate layer distal from the piezoelectric substrate; and a passivation layer disposed on a side of the intermediate layer distal from the piezoelectric substrate, wherein the sound velocity adjustment layer is located in the center region and overlaps portions of the plurality of interdigital electrodes located in the center region in a direction normal to a major surface of the piezoelectric substrate and is configured to change a sound velocity of the center region.

2. The surface acoustic wave resonator device of claim 1, wherein the sound velocity adjustment layer is configured to speed up the sound velocity of the center region such that the sound velocity of the center region is different from sound velocities of the first and second end regions.

3. The surface acoustic wave resonator device of claim 1 or 2, wherein a footprint of the portions of the plurality of interdigital electrodes located in the center region on the piezoelectric substrate is within a footprint of the sound velocity adjustment layer on the piezoelectric substrate.

4. The surface acoustic wave resonator device of any one of claims 1 to 3, wherein footprints of portions of the plurality of interdigital electrodes located in the first end region, the second end region, the first peripheral region, and the second peripheral region on the piezoelectric substrate are offset from a footprint of the sound velocity adjustment layer on the piezoelectric substrate.

5. The surface acoustic wave resonator device of any one of claims 1 to 4, wherein the intermediate layer has a recess, and at least a portion of the sound velocity adjustment layer is located in the recess of the intermediate layer.

6. The surface acoustic wave resonator device of claim 5, wherein a footprint of the sound velocity adjustment layer on the piezoelectric substrate is offset from a footprint of the passivation layer on the piezoelectric substrate.

7. The surface acoustic wave resonator device of claim 5, wherein the passivation layer also covers a surface of the sound velocity adjustment layer distal from the piezoelectric substrate.

8. The surface acoustic wave resonator device of claim 5, wherein a surface of the sound velocity adjustment layer distal from the piezoelectric substrate is flush with a surface of the intermediate layer distal from the piezoelectric substrate in a direction parallel to a major surface of the piezoelectric substrate. ​ 9. The SAW resonator device of claim 5, wherein a distance of a surface of the acoustic velocity adjustment layer on a side distal from the piezoelectric substrate from a major surface of the piezoelectric substrate is greater or less than a distance of a surface of the intermediate layer on a side distal from the piezoelectric substrate from the major surface of the piezoelectric substrate in a direction normal to the major surface of the piezoelectric substrate.

10. The SAW resonator device of any one of claims 1 to 9, wherein the acoustic velocity adjustment layer is on a side of the passivation layer distal from the piezoelectric substrate and covers a portion of a surface of the passivation layer.

11. The SAW resonator device of any one of claims 1 to 10, wherein the acoustic velocity adjustment layer is buried in the intermediate layer and a surface of the acoustic velocity adjustment layer on a side distal from the piezoelectric substrate is covered by the intermediate layer.

12. The SAW resonator device of any one of claims 1 to 11, wherein the intermediate layer comprises a temperature compensation layer and the acoustic velocity adjustment layer and the temperature compensation layer comprise different materials.

13. The SAW resonator device of any one of claims 1 to 12, wherein the acoustic velocity adjustment layer comprises silicon nitride, aluminum nitride, or a combination thereof.

14. The SAW resonator device of any one of claims 1 to 13, further comprising: a first protruding structure disposed at the first end region and the second end region and configured to change an acoustic velocity of the first end region and the second end region.

15. The SAW resonator device of claim 14, wherein the first protruding structure is configured to decrease the acoustic velocity of the first end region and the second end region.

16. The SAW resonator device of claim 14, wherein the first protruding structure is disposed in a same layer as the interdigital transducer and comprises end portions of the plurality of interdigital electrodes located at the first end region and the second end region; the end portions of the plurality of interdigital electrodes each have a second width in the second direction, portions of the plurality of interdigital electrodes located at the center region each have a first width in the second direction, and the second width is greater than the first width.

17. The SAW resonator device of claim 14, wherein the first protruding structure comprises a plurality of first mass load blocks respectively disposed on a side of end portions of the plurality of interdigital electrodes located at the first end region and the second end region distal from the piezoelectric substrate.

18. The SAW resonator device of claim 17, wherein each first mass load block overlaps an end portion of a corresponding one of the interdigital electrodes in a direction normal to a major surface of the piezoelectric substrate and has sidewalls aligned in the direction normal to the major surface of the piezoelectric substrate.

19. The SAW resonator device of claim 14, wherein a footprint of the acoustic velocity adjustment layer on the piezoelectric substrate is offset from a footprint of the first protruding structure on the piezoelectric substrate. ​ ​ 20. The SAW resonator device of any one of claims 1 to 19, wherein the acoustic velocity of the central region is higher than the acoustic velocity of the first end region and the second end region.

21. The SAW resonator device of any one of claims 1 to 20, wherein the IDT further comprises: a first bus bar and a second bus bar located on opposite sides of the interdigital electrode region in the first direction, and each extending in the second direction, wherein the first bus bar is located on one side of the first perimeter region and connected to the first interdigital electrode, and the second bus bar is located on one side of the second perimeter region and connected to the second interdigital electrode.

22. The SAW resonator device of claim 21, further comprising: a first additional bus bar located in the first perimeter region, extending in the second direction, and connected to the first interdigital electrode; and a second additional bus bar located in the second perimeter region, extending in the second direction, and connected to the second interdigital electrode.

23. The SAW resonator device of any one of claims 1 to 22, further comprising: a first reflector grating and a second reflector grating disposed on the piezoelectric substrate and arranged on opposite sides of the IDT in the second direction, wherein the acoustic velocity adjustment layer has a footprint on the piezoelectric substrate that is offset from the footprints of the first reflector grating and the second reflector grating on the piezoelectric substrate; or the acoustic velocity adjustment layer has a footprint on the piezoelectric substrate that overlaps the footprint of the first reflector grating and / or the second reflector grating on the piezoelectric substrate. a second protruding structure disposed in the extended region of the first end region and the second end region in the second direction, and the second protruding structure comprises a portion of the first reflector grating and / or the second reflector grating, or the second protruding structure has a footprint on the piezoelectric substrate that overlaps the footprint of the first reflector grating and / or the second reflector grating on the piezoelectric substrate.

25. The SAW resonator device of claim 24, wherein the first reflector grating and the second reflector grating each comprise a plurality of reflector electrodes extending in the first direction and arranged in the second direction, wherein each reflector electrode comprises a first electrode portion, a second electrode portion, and a third electrode portion located in the extended region of the central region, the first end region, and the second end region in the second direction, respectively, 24. The surface acoustic wave resonator device of claim 23, further comprising: the second electrode portion and the third electrode portion have a width in the second direction that is greater than a width of the first electrode portion in the second direction, and the second protruding structure comprises the second electrode portions and the third electrode portions of the plurality of reflector electrodes.

26. The SAW resonator device of claim 24, wherein the second protruding structure comprises a plurality of second mass loading blocks disposed on a side of the plurality of reflector electrodes of the first reflector grating and the second reflector grating distal from the piezoelectric substrate and located in the extended region of the first end region and the second end region in the second direction. ​ ​ 27. A method of manufacturing a surface acoustic wave resonator device, wherein the surface acoustic wave resonator device has an interdigital electrode region including, in a first direction, a first perimeter region, a first end region, a center region, a second end region, and a second perimeter region, sequentially arranged, and the method of manufacturing comprises: providing a piezoelectric substrate; forming an interdigital transducer on the piezoelectric substrate, the interdigital transducer including a plurality of interdigital electrodes located in the interdigital electrode region and including a first interdigital electrode and a second interdigital electrode; the first interdigital electrode and the second interdigital electrode extending along the first direction and alternatingly arranged along a second direction intersecting the first direction; the first interdigital electrode extending from the first perimeter region to the second end region, the second interdigital electrode extending from the second perimeter region to the first end region; forming an intermediate layer on the piezoelectric substrate to cover the interdigital transducer; forming a sound velocity adjustment layer on a side of at least a portion of the intermediate layer distal from the piezoelectric substrate; and forming a passivation layer on a side of the intermediate layer distal from the piezoelectric substrate, wherein the sound velocity adjustment layer is located in the center region and overlaps with portions of the plurality of interdigital electrodes located in the center region in a direction perpendicular to a major surface of the piezoelectric substrate and is configured to change a sound velocity of the center region.

28. The method of manufacturing according to claim 27, wherein forming the sound velocity adjustment layer on a side of at least a portion of the intermediate layer distal from the piezoelectric substrate comprises: performing an etching process on the intermediate layer to remove portions of the intermediate layer located in the center region to form a recess in the intermediate layer; and forming the sound velocity adjustment layer in the recess of the intermediate layer.

29. The method of manufacturing according to claim 27 or 28, wherein forming the passivation layer comprises: forming the passivation layer in regions other than the center region such that the passivation layer exposes the sound velocity adjustment layer; or the passivation layer is also formed in the center region and covers a surface of the sound velocity adjustment layer distal from the piezoelectric substrate.

30. The method of manufacturing according to any one of claims 27 to 29, wherein the sound velocity adjustment layer is formed on a side of the passivation layer distal from the piezoelectric substrate after the passivation layer is formed on a side of the intermediate layer distal from the piezoelectric substrate.

31. The method of manufacturing according to any one of claims 27 to 30, wherein the intermediate layer includes a first intermediate sub-layer and a second intermediate sub-layer, and forming the intermediate layer and the sound velocity adjustment layer comprises: forming the sound velocity adjustment layer on a side of the first intermediate sub-layer distal from the piezoelectric substrate after forming the first intermediate sub-layer; and forming the second intermediate sub-layer on a side of the first intermediate sub-layer distal from the piezoelectric substrate to cover the first intermediate sub-layer and the sound velocity adjustment layer after forming the sound velocity adjustment layer. ​ ​ ​

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