Surface acoustic wave resonator and manufacturing method therefor

Abstract

Provided in the present invention are a surface acoustic wave resonator and a manufacturing method therefor. An interdigital transducer comprises a plurality of interdigital electrodes and two busbar groups connected to the interdigital electrodes. In each busbar group, a busbar close to an interdigital electrode is arranged at an angle relative to the normal direction of the interdigital electrode, thereby enabling the lateral mode to be inhibited. Furthermore, one end of the interdigital electrode is provided with a mass block, thereby enabling the sound velocity at the end of the interdigital electrode to be reduced. Furthermore, each busbar group comprises at least two busbars, and adjacent busbars are connected, so that energy can be limited in a resonant cavity, inhibiting energy leakage, ultimately resulting in a significant increase in the quality factor.

Description

Surface acoustic wave resonator and method for manufacturing the same Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a surface acoustic wave resonator and a manufacturing method thereof. Background Art

[0002] The RF front end is the core of modern mobile communication systems. As an important component of the RF front end, the performance of the filter directly determines the ability of the signal to stand out from the noise in the communication system. With the rapid development of the Internet of Things, the demand for data transmission capabilities has further increased, and the filter requires smaller in-band insertion loss and better out-of-band suppression. As the basic component of the filter, the resonator is required to have a higher Q value (Quality Factor). In recent years, the TF (Thin Film) SAW (Surface Acoustic Wave) resonator has a laminated structure with good energy confinement in the thickness direction, but it also introduces some lateral modal response and lateral energy leakage, resulting in a decrease in the Q value. How to improve the Q value of the resonator has always been the pursuit of those skilled in the art.

[0003] Summary of the Invention

[0004] The object of the present invention is to provide a surface acoustic wave resonator and a manufacturing method thereof, so as to improve the Q value of the resonator.

[0005] In order to solve the above technical problems, the present invention provides a surface acoustic wave resonator, which includes: a piezoelectric layer and an interdigital transducer formed on the piezoelectric layer;

[0006] The interdigital transducer includes a plurality of interdigital electrodes and two bus bar groups connected to the interdigital electrodes, wherein each of the bus bar groups includes at least two bus bars and adjacent bus bars are connected, the bus bar close to the interdigital electrode in each bus bar group is set at an angle to the normal of the interdigital electrode, and a mass block is set at the end of the interdigital electrode.

[0007] Optionally, in the surface acoustic wave resonator, the bus bars close to the interdigital electrodes in each bus bar group are arranged at an angle to the x-crystal axis of the piezoelectric layer.

[0008] Optionally, in the surface acoustic wave resonator, the two bus bar groups have the same structure.

[0009] Optionally, in the surface acoustic wave resonator, adjacent bus bars in each bus bar group are arranged in parallel or at an angle.

[0010] Optionally, in the surface acoustic wave resonator, the bus bar group further includes a connecting bar, and adjacent bus bars in each bus bar group are connected via the connecting bar.

[0011] Optionally, in the surface acoustic wave resonator, the maximum distance between adjacent bus bars in each bus bar group is greater than or equal to a period of the interdigital electrodes.

[0012] Optionally, in the surface acoustic wave resonator, an angle between the bus bar close to the interdigital electrode in each bus bar group and the normal direction of the interdigital electrode is between 2° and 20° or between -20° and -2°.

[0013] Optionally, in the surface acoustic wave resonator, the interdigitated electrodes include only true finger electrodes, a first end of the true finger electrode is connected to the bus bar group, and a second end of the true finger electrode is provided with the mass block;

[0014] Alternatively, the interdigitated electrodes include real finger electrodes and dummy finger electrodes, the first ends of the real finger electrodes and the first ends of the dummy finger electrodes are respectively connected to different bus bar groups, and the second ends of the real finger electrodes and / or the second ends of the dummy finger electrodes are provided with the mass block.

[0015] Optionally, in the surface acoustic wave resonator, the ratio of the length of the mass block to the period of the interdigitated electrode is between 0.25 and 1, wherein the length of the mass block is the maximum dimension of the mass block in the extension direction of the interdigitated electrode; the ratio of the width of the mass block to the width of the interdigitated electrode is between 1.2 and 2, wherein the width of the mass block is the maximum dimension of the mass block in the normal direction of the interdigitated electrode.

[0016] Optionally, in the surface acoustic wave resonator, the surface acoustic wave resonator further includes reflectors located on both sides of the interdigital transducer.

[0017] Optionally, in the surface acoustic wave resonator, the surface acoustic wave resonator further includes a substrate layer, a trap layer and / or a first dielectric layer located below the piezoelectric layer; and / or the surface acoustic wave resonator further includes a second dielectric layer covering the interdigital transducer.

[0018] Optionally, in the surface acoustic wave resonator, the angle between the bus bar in the bus bar group close to the interdigital electrode and the normal direction of the interdigital electrode is equal to the energy flow angle of the surface acoustic wave resonator. The present invention also provides a method for manufacturing a surface acoustic wave resonator, the method for manufacturing a surface acoustic wave resonator comprising:

[0019] providing a piezoelectric layer;

[0020] forming an interdigital transducer on the piezoelectric layer, the interdigital transducer comprising a plurality of interdigital electrodes and two bus bar groups connected to the interdigital electrodes, wherein each bus bar group comprises at least two bus bars and adjacent bus bars are connected, and the bus bars in each bus bar group close to the interdigital electrodes are arranged at an angle to the normal direction of the interdigital electrodes; and

[0021] A mass is formed at the ends of the interdigital electrodes.

[0022] Optionally, in the method for manufacturing the surface acoustic wave resonator, forming an interdigital transducer on the piezoelectric layer includes:

[0023] forming a metal layer on the piezoelectric layer; and,

[0024] The metal layer is etched to form the IDT.

[0025] Optionally, in the method for manufacturing the surface acoustic wave resonator, the mass block includes a metal mass layer; and when etching the metal layer to form the interdigital transducer, the metal mass layer is also formed.

[0026] In the surface acoustic wave resonator and its manufacturing method provided by the present invention, the interdigital transducer includes a plurality of interdigital electrodes and two busbar groups connected to the interdigital electrodes. The busbars close to the interdigital electrodes in each busbar group are arranged at an angle to the normal direction of the interdigital electrodes, thereby suppressing the transverse mode. Furthermore, a mass block is provided at the end of the interdigital electrodes, thereby reducing the speed of sound at the end of the interdigital electrodes. Furthermore, each busbar group includes at least two busbars and two adjacent busbars are connected, so that energy can be confined to the resonant cavity, energy leakage can be suppressed, and ultimately the Q value is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a schematic cross-sectional view of a surface acoustic wave resonator according to an embodiment of the present invention.

[0028] FIG. 2 is a schematic cross-sectional view of another surface acoustic wave resonator according to an embodiment of the present invention.

[0029] FIG3 is a schematic cross-sectional view of another surface acoustic wave resonator according to an embodiment of the present invention.

[0030] FIG4 is a schematic cross-sectional view of another surface acoustic wave resonator according to an embodiment of the present invention.

[0031] FIG. 5 is a schematic top view of an IDT in a surface acoustic wave resonator according to an embodiment of the present invention.

[0032] FIG6 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0033] FIG. 7 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0034] FIG8 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0035] FIG9 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0036] FIG10 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0037] FIG. 11 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0038] FIG12 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0039] FIG13 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0040] FIG. 14 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0041] FIG15 is a schematic top view of an IDT in another surface acoustic wave resonator according to an embodiment of the present invention.

[0042] FIG. 16 is a schematic diagram comparing the transverse modal responses of the surface acoustic wave resonator according to the embodiment of the present invention and a traditional surface acoustic wave resonator.

[0043] FIG. 17 is a schematic diagram showing a comparison of the Q values ​​of the surface acoustic wave resonator according to an embodiment of the present invention and a traditional surface acoustic wave resonator.

[0044] FIG18 is a schematic top view of an IDT in a conventional surface wave resonator.

[0045] The description of the accompanying drawings is as follows:

[0046] 10-Surface acoustic wave resonator;

[0047] 100 - piezoelectric layer; 110 - substrate layer; 120 - trap layer; 130 - first dielectric layer; 140 - second dielectric layer;

[0048] 200 - IDT; 210 - IDT electrodes; 211 - True finger electrodes; 212 - Dummy finger electrodes; 220 - Bus bar group; 220a - Upper bus bar group; 220b - Lower bus bar group; 221 - Bus bar; 2210a - Upper first bus bar; 2210b - Lower first bus bar; 2211a - Upper second bus bar; 2211b - Lower second bus bar; 222 - Connecting bar; 222a - Upper connecting bar; 222b - Lower connecting bar;

[0049] 300-mass block;

[0050] 400 - reflector; 410 - reflective grid; 420 - reflective busbar group; 420a - upper reflective busbar group; 420b - lower reflective busbar group; 421 - reflective busbar; 4210a - upper first reflective busbar; 4210b - lower first reflective busbar; 4211a - upper second reflective busbar; 4211b - lower second reflective busbar;

[0051] 500-interdigital transducer; 510-interdigital electrode; 520-bus bar;

[0052] F-normal; a1-first angle; a2-second angle; a3-third angle; H-distance; W-period; L1-length; L2, L3-width; S1, S2, S3, S4-curves. DETAILED DESCRIPTION

[0053] The following is a detailed description of the surface acoustic wave resonator and its manufacturing method proposed in the present invention, with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are greatly simplified and not to exact scale, and are intended solely to facilitate and clarify the purpose of illustrating the embodiments of the present invention.

[0054] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the invention. Unless otherwise defined herein, technical or scientific terms used herein shall have the ordinary meaning as understood by a person of ordinary skill in the art to which the invention pertains. The terms "first," "second," and similar terms used in the specification and claims of the present invention do not denote any order, quantity, or importance, but are simply used to distinguish one component from another. Similarly, terms such as "a" or "an" do not denote a limitation of quantity, but rather denote the presence of at least one. "Multiple" or "several" refer to two or more. Unless otherwise indicated, terms such as "upper" and / or "lower" are for convenience only and are not intended to limit the invention to a specific location or spatial orientation. Terms such as "include" or "comprising" mean that the elements or structures preceding the term "include" or "comprising" encompass the elements or structures listed after the term and their equivalents, and do not exclude other elements or structures. Terms such as "connected" or "connected" are not limited to physical or mechanical connections and may include electrical connections, whether direct or indirect. As used in the present description and the appended claims, the singular forms "a," "an," "said," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0055] Please refer to Figure 1, which is a cross-sectional schematic diagram of a surface acoustic wave resonator according to an embodiment of the present invention. As shown in Figure 1, in one embodiment of the present application, the surface acoustic wave resonator 10 includes: a piezoelectric layer 100 and an interdigital transducer 200 formed on the piezoelectric layer 100. The material of the piezoelectric layer 100 can be, for example, LT (lithium tantalate), LN (lithium niobate), AlN (aluminum nitride), PZT (lead zirconate titanate piezoelectric ceramic) or ZnO (zinc oxide). The piezoelectric layer 100 has an x-axis, a y-axis and a z-axis that are perpendicular to each other, wherein the x-axis and the y-axis are parallel to the surface of the piezoelectric layer 100, and the z-axis is perpendicular to the surface of the piezoelectric layer 100. The material of the interdigital transducer 200 is metal, and specifically can be, for example, gold, silver, aluminum, copper, tungsten, titanium, nickel, metal alloys, etc.

[0056] Further, please refer to Figures 2 to 4, which are cross-sectional schematic diagrams of another surface acoustic wave resonator according to an embodiment of the present invention. As shown in Figures 2 to 4, in other embodiments of the present application, the surface acoustic wave resonator 10 may further include a substrate layer 110, a trap layer 120, and / or a first dielectric layer 130 located below the piezoelectric layer 100; wherein the substrate layer 110 may be made of, for example, silicon; the trap layer 120 may be made of, for example, polycrystalline silicon; and the first dielectric layer 130 may be made of, for example, silicon dioxide, silicon nitride, or the like.

[0057] Furthermore, the surface acoustic wave resonator 10 may further include a second dielectric layer 140 covering the IDT 200. The material of the second dielectric layer 140 may be, for example, silicon dioxide, silicon nitride, or the like. The material of the second dielectric layer 140 may be the same as or different from that of the first dielectric layer 130. For example, as shown in Figures 1 and 4 , the second dielectric layer 140 covers the IDT 200.

[0058] The surface acoustic wave resonator 10 may include the substrate layer 110 , the trap layer 120 , the first dielectric layer 130 and the second dielectric layer 140 at the same time, or may include only one or more of them.

[0059] As shown in FIG. 2 , in one embodiment of the present application, the surface acoustic wave resonator 10 may include a substrate layer 110 and a first dielectric layer 130 , wherein the first dielectric layer 130 is located on the substrate layer 110 , and the piezoelectric layer 100 is located on the first dielectric layer 130 .

[0060] As shown in Figure 3, in another embodiment of the present application, the surface acoustic wave resonator 10 may include a substrate layer 110, a trap layer 120 and a first dielectric layer 130, wherein the trap layer 120 is located on the substrate layer 110, the first dielectric layer 130 is located on the trap layer 120, and the piezoelectric layer 100 is located on the first dielectric layer 130.

[0061] As shown in Figure 4, in another embodiment of the present application, the surface acoustic wave resonator 10 may include a substrate layer 110, a first dielectric layer 130 and a second dielectric layer 140, wherein the first dielectric layer 130 is located on the substrate layer 110, the piezoelectric layer 100 is located on the first dielectric layer 130, the interdigital transducer 200 is located on the piezoelectric layer 100, and the second dielectric layer 140 covers the interdigital transducer 200.

[0062] Further, please refer to Figures 5 to 15, which are schematic top views of an IDT in a surface acoustic wave resonator according to an embodiment of the present invention. First, please refer to Figure 5. In an embodiment of the present invention, the IDT 200 includes a plurality of interdigital electrodes 210 and two busbar groups 220 connected to the interdigital electrodes 210, respectively referred to herein as an upper busbar group 220a and a lower busbar group 220b.

[0063] Each bus bar group 220 includes at least two bus bars 221. Furthermore, the bus bars 221 are arranged sequentially along the extension direction of the interdigitated electrodes 210, and adjacent bus bars 221 are connected. Specifically, each bus bar group 220 also includes a connecting bar 222, and adjacent bus bars 221 in each bus bar group 220 are connected via the connecting bar 222.

[0064] Furthermore, the busbars 221 in each busbar group 220, located near the interdigital electrodes 210, are arranged at an angle to the normal F of the interdigital electrodes 210. Mass blocks 300 are provided at the ends of the interdigital electrodes 210. This suppresses transverse modes and reduces the speed of sound at the ends of the interdigital electrodes 210, confining energy within the resonant cavity, suppressing energy leakage and significantly improving the Q value.

[0065] Continuing with reference to FIG5 , in one embodiment of the present invention, the upper busbar assembly 220a includes two busbars 221, here a first upper busbar 2210a and a second upper busbar 2211a. In this embodiment of the present application, the ends of the first upper busbar 2210a are connected to the ends of the second upper busbar 2211a. Specifically, the upper busbar assembly 220a further includes two upper connecting bars 222a, and the ends of the first upper busbar 2210a are connected to the ends of the second upper busbar 2211a via the two upper connecting bars 222a.

[0066] Furthermore, the lower bus bar assembly 220b includes two bus bars 221, namely a lower first bus bar 2210b and a lower second bus bar 2211b. The ends of the lower first bus bar 2210b are connected to the ends of the lower second bus bar 2211b. Specifically, the lower bus bar assembly 220b also includes two lower connecting bars 222b, and the ends of the lower first bus bar 2210b are connected to the ends of the lower second bus bar 2211b via the two lower connecting bars 222b.

[0067] Furthermore, each of the upper bus bar group 220a and the lower bus bar group 220b may include more bus bars 221, for example, three, four, five, etc. Adjacent bus bars 221 in each bus bar group 220 may be connected at the ends, or at any position other than the ends, such as the middle, or between the middle and the ends. For example, as shown in FIG12 , each of the upper bus bar group 220a and the lower bus bar group 220b includes four bus bars 221. As shown in FIG12 , adjacent bus bars 221 in each bus bar group 220 are connected by four connecting bars 222. Specifically, the two ends of adjacent bus bars 221 and the position between the two ends are connected by the connecting bars 222.

[0068] In the embodiment of the present application, the upper busbar group 220a and the lower busbar group 220b have the same structure. Specifically, the number, shape, position, and connection relationship of the busbars 221 included in the upper busbar group 220a are the same as those of the lower busbar group 220b.

[0069] In other embodiments of the present application, the structures of the upper busbar group 220a and the lower busbar group 220b may also be different. For example, the upper busbar group 220a includes two busbars 221, and the two busbars 221 are connected only at the two ends; the lower busbar group 220b includes two busbars 221, and the two busbars 221 are connected at the two ends and the middle. For another example, the upper busbar group 220a includes three busbars 221, and the two ends of adjacent busbars 221 are connected; the lower busbar group 220b includes four busbars 221, and the two ends of adjacent busbars 221 are connected.

[0070] Please continue to refer to Figure 5. In one embodiment of the present application, the bus bars 221 in each bus bar group 220 are arranged parallel to each other, that is, the upper first bus bar 2210a and the upper second bus bar 2211a are parallel, and the lower first bus bar 2210b and the lower second bus bar 2211b are parallel.

[0071] In another embodiment of the present application, the busbars 221 in each busbar group 220 may also be non-parallel. For example, the upper first busbar 2210a and the upper second busbar 2211a are non-parallel. For example, as shown in FIG13 , the upper first busbar 2210a and the upper second busbar 2211a are arranged at an angle, and further, the upper first busbar 2210a and the upper second busbar 2211a intersect at the right end in the figure; the lower first busbar 2210b and the lower second busbar 2211b are also arranged at an angle, and further, the lower first busbar 2210b and the lower second busbar 2211b intersect at the left end in the figure. As shown in Figure 13, the upper bus bar group 220a also includes a connecting bar 222, and the left end of the upper first bus bar 2210a is connected to the left end of the upper second bus bar 2211a through the connecting bar 222; the lower bus bar group 220b also includes a connecting bar 222, and the right end of the lower first bus bar 2210b is connected to the right end of the lower second bus bar 2211b through the connecting bar 222.

[0072] In the embodiment of the present application, the upper bus bar group 220a and the lower bus bar group 220b have the same structure, and the following will mainly focus on the lower bus bar group 220b for further description.

[0073] Specifically, the bus bar 221 in each bus bar group 220, which is close to the interdigital electrode 210, is arranged at an angle with the normal direction F of the interdigital electrode 210. That is, the upper first bus bar 2210a and the lower first bus bar 2210b are respectively arranged at an angle with the normal direction F of the interdigital electrode 210. Here, the upper bus bar group 220a and the lower bus bar group 220b have the same structure. Accordingly, the angle between the upper first bus bar 2210a and the normal direction F of the interdigital electrode 210 is the same as the angle between the lower first bus bar 2210b and the normal direction F of the interdigital electrode 210.

[0074] Continuing with reference to FIG5 , optionally, the angle between the bus bar 221 near the interdigital electrode 210 in each bus bar group 220 and the normal F of the interdigital electrode 210 is between 2° and 20° or -20° and -2°. Here, the first angle a1 between the lower first bus bar 2210b and the normal F of the interdigital electrode 210 is between 2° and 20° or -20° and -2°, i.e., the clockwise or counterclockwise angle between the lower first bus bar 2210b and the normal F of the interdigital electrode 210 is between 2° and 20°. Optionally, the angle between the bus bar 221 near the interdigital electrode 210 in each bus bar group 220 and the normal F of the interdigital electrode 210 is equal to the energy flow angle of the surface acoustic wave resonator 10, thereby ensuring that the propagation directions of the group velocity and the phase velocity are consistent, thereby maximally suppressing the transverse mode.

[0075] Optionally, the angles between the remaining bus bars 221 in each bus bar group 220 and the normal direction F of the interdigital electrode 210 are all between -20° and 20°, that is, the clockwise angle or counterclockwise angle between the remaining bus bars 221 in each bus bar group 220 and the normal direction F of the interdigital electrode 210 is between 0° and 20°. That is, in the embodiment of the present application, the remaining bus bars 221 in each bus bar group 220 can be arranged parallel to or at an angle to the normal direction F of the interdigital electrode 210. Here, the second angle a2 between the lower second bus bar 2211b and the normal direction F of the interdigital electrode 210 is between -20° and 20°.

[0076] Continuing with FIG5 , optionally, the maximum distance H between adjacent bus bars 221 in each bus bar group 220 is greater than or equal to the period W of the interdigital electrodes 210 . This improves the suppression of energy leakage and significantly increases the Q value. Here, the maximum distance H between adjacent bus bars 221 in each bus bar group 220 is the spacing between adjacent bus bars 221 in each bus bar group 220 along the extension direction of the interdigital electrodes 210 , and the period W of the interdigital electrodes 210 is the distance between the same-side edges of adjacent interdigital electrodes 210 .

[0077] In the embodiment of the present application, the adjacent bus bars 221 in each bus bar group 220 are arranged in parallel, and accordingly, the distance H between the adjacent bus bars 221 in each bus bar group 220 is a constant value, that is, the distances between the adjacent bus bars 221 in each bus bar group 220 are equal at all locations. In other embodiments of the present application, the bus bars 221 in each bus bar group 220 may also be arranged non-parallel, and accordingly, the distance H between the adjacent bus bars 221 in each bus bar group 220 is a variable value. Optionally, the maximum distance H between the adjacent bus bars 221 in each bus bar group 220 is greater than or equal to the period W of the interdigital electrodes 210.

[0078] Furthermore, in one embodiment of the present application, the interdigital electrodes 210 include only true finger electrodes 211, one end of each true finger electrode 211 being connected to the bus bar assembly 220, and the other end of each true finger electrode 211 being provided with the mass block 300. The line connecting (the center of) the mass block 300 near the upper bus bar assembly 220a can be a straight line or a zigzag line; the line connecting (the center of) the mass block 300 near the lower bus bar assembly 220b can also be a straight line or a zigzag line.

[0079] As shown in Figure 5, four true finger electrodes 211 are schematically illustrated, with adjacent true finger electrodes 211 connected to different busbar groups 220. In Figure 5, the mass blocks 300 are only provided at the ends of the true finger electrodes 211. Furthermore, the line connecting (the center of) the mass blocks 300 near the upper busbar group 220a can be parallel to the upper first busbar 2210a; and the line connecting (the center of) the mass blocks 300 near the lower busbar group 220b can be parallel to the lower first busbar 2210b, thereby further reducing the acoustic velocity at the ends of each interdigital electrode 210.

[0080] 6 and 7 , in another embodiment of the present application, in addition to providing the mass block 300 at the end of the true finger electrode 211, a mass block 300 may also be provided at a specific position of the true finger electrode 211. Optionally, the specific position is a position of the true finger electrode 211 corresponding to the end of an adjacent true finger electrode 211.

[0081] As shown in Figure 6, four true finger electrodes 211 are schematically shown, and two mass blocks 300 are provided on each true finger electrode 211, and the line connecting (the center of) the mass blocks 300 close to the upper bus bar group 220a is parallel to the upper first bus bar 2210a; the line connecting (the center of) the mass blocks 300 close to the lower bus bar group 220b is parallel to the lower first bus bar 2210b.

[0082] As shown in Figure 7, four true finger electrodes 211 are schematically shown in the figure, and two mass blocks 300 are set on each true finger electrode 211, and the four mass blocks 300 (centers) close to the upper bus bar group 220a are not in a straight line; the four mass blocks 300 (centers) close to the lower bus bar group 220b are also not in a straight line. In the mass blocks 300 on the first true finger electrode 211 and the second true finger electrode 211, the line connecting (the centers of) the two mass blocks 300 close to the upper bus bar group 220a is parallel to the normal F of the interdigital electrode 210, and the line connecting (the centers of) the two mass blocks 300 close to the lower bus bar group 220b is parallel to the normal F of the interdigital electrode 210; in the mass blocks 300 on the third true finger electrode 211 and the fourth true finger electrode 211, the line connecting (the centers of) the two mass blocks 300 close to the upper bus bar group 220a is parallel to the normal F of the interdigital electrode 210, and the line connecting (the centers of) the two mass blocks 300 close to the lower bus bar group 220b is parallel to the normal F of the interdigital electrode 210.

[0083] In another embodiment of the present application, the interdigitated electrode 210 includes a real finger electrode 211 and a dummy finger electrode 212, one end of the real finger electrode 211 and one end of the dummy finger electrode 212 are respectively connected to different bus bar groups 220, and the other end of the real finger electrode 211 and / or the other end of the dummy finger electrode 212 is provided with the mass block 300. Among them, the connecting line of the mass block 300 (center) on the true finger electrode 211 close to the upper bus bar group 220a can be a straight line or a broken line; the connecting line of the mass block 300 (center) on the dummy finger electrode 212 close to the upper bus bar group 220a can be a straight line or a broken line; the connecting line of the mass block 300 (center) on the true finger electrode 211 close to the lower bus bar group 220b can also be a straight line or a broken line; the connecting line of the mass block 300 (center) on the dummy finger electrode 212 close to the lower bus bar group 220b can also be a straight line or a broken line.

[0084] As shown in Figure 8, four true finger electrodes 211 and corresponding four dummy finger electrodes 212 are schematically illustrated. Here, the mass block 300 is only provided at the end of each true finger electrode 211. Furthermore, the line connecting (the center of) the mass block 300 near the upper bus bar group 220a can be parallel to the upper first bus bar 2210a; and the line connecting (the center of) the mass block 300 near the lower bus bar group 220b can be parallel to the lower first bus bar 2210b.

[0085] As shown in Figure 9, four true finger electrodes 211 and corresponding four dummy finger electrodes 212 are schematically illustrated. Here, the mass block 300 is only provided at the end of each dummy finger electrode 212. Furthermore, the line connecting (the center of) the mass block 300 near the upper bus bar group 220a can be parallel to the upper first bus bar 2210a; the line connecting (the center of) the mass block 300 near the lower bus bar group 220b can be parallel to the lower first bus bar 2210b.

[0086] As shown in Figure 10, four real finger electrodes 211 and corresponding four dummy finger electrodes 212 are schematically shown. Here, the end of each real finger electrode 211 and the end of each dummy finger electrode 212 are provided with the mass block 300. Among them, the line connecting (the center of) the mass block 300 near the end of the true finger electrode 211 of the upper bus bar group 220a is parallel to the upper first bus bar 2210a; the line connecting (the center of) the mass block 300 near the end of the dummy finger electrode 212 of the upper bus bar group 220a is parallel to the upper first bus bar 2210a; the line connecting (the center of) the mass block 300 near the end of the true finger electrode 211 of the lower bus bar group 220b is parallel to the lower first bus bar 2210b; the line connecting (the center of) the mass block 300 near the end of the dummy finger electrode 212 of the lower bus bar group 220b is parallel to the lower first bus bar 2210b.

[0087] In other embodiments of the present application, in addition to providing the mass block 300 at the end of the real electrode 211 and / or the end of the dummy electrode 212, the mass block 300 may further be provided at a specific position of the real electrode 211 and / or the dummy electrode 212. Optionally, the specific position is a position of the real electrode 211 and / or the dummy electrode 212 corresponding to the end of the adjacent real electrode 211 and / or the dummy electrode 212.

[0088] Furthermore, in the embodiment of the present application, the mass block 300 on the surface of the surface acoustic wave resonator 10 is square in shape. In other embodiments of the present application, the mass block 300 may also be in other shapes, such as circular, X-shaped, or V-shaped. The shapes of the mass blocks 300 on each of the interdigital electrodes 210 may be the same or different.

[0089] Optionally, the ratio of the length L1 of the mass block 300 to the period W of the interdigital electrodes 210 is between 0.25 and 1, wherein the length L1 of the mass block 300 is the maximum dimension of the mass block 300 in the direction in which the interdigital electrodes 210 extend. The ratio of the width L2 of the mass block 300 to the width L3 of the interdigital electrodes 210 is between 1.2 and 2, wherein the width L2 of the mass block 300 is the maximum dimension of the mass block 300 in the normal direction F of the interdigital electrodes 210. This ensures both effective suppression of energy leakage and guaranteed transmission efficiency of acoustic waves.

[0090] Furthermore, the material of the mass block 300 includes metal and / or dielectric materials. For example, the material of the mass block 300 may include gold, silver, aluminum, copper, tungsten, silicon, silicon dioxide, polysilicon, silicon nitride, etc. The mass block 300 may be located in the same film layer as the IDT 200, or in a different film layer from the IDT 200; alternatively, the mass block 300 may include multiple mass layers, wherein one mass layer may be located in the same film layer as the IDT 200, which is not limited in this application. Furthermore, for multiple mass layers, the shape and / or size of each mass layer may be the same or different, which is not limited in this application.

[0091] Please continue to refer to Figures 5 to 10 and Figures 12 and 13. In one embodiment of the present application, the normal direction F of the interdigital electrode 210 extends along the x-crystal axis of the piezoelectric layer 100, that is, the interdigital electrode 210 extends along the y-crystal axis of the piezoelectric layer 100; the extension direction of the upper first bus bar 2210a and the lower first bus bar 2210b is set at an angle to the normal direction F of the interdigital electrode 210, that is, the upper first bus bar 2210a and the lower first bus bar 2210b are arranged at an angle to the normal direction F of the interdigital electrode 210, that is, the upper first bus bar 2210b is set at an angle to the normal direction F of the interdigital electrode 210. The extension direction of 2210a and the lower first bus bar 2210b and the x-crystal axis of the piezoelectric layer 100 are also set at an angle, and the angle between the extension direction of the upper first bus bar 2210a and the lower first bus bar 2210b and the normal F of the interdigitated electrode 210 is equal to the angle between the extension direction of the upper first bus bar 2210a and the lower first bus bar 2210b and the x-crystal axis of the piezoelectric layer 100.

[0092] Please refer to Figure 11. In another embodiment of the present application, the normal direction F of the interdigital electrode 210 is set at an angle to the x-crystal axis of the piezoelectric layer 100. The extension direction of the upper first bus bar 2210a and the lower first bus bar 2210b is set at an angle to the normal direction F of the interdigital electrode 210. And further, as shown in Figure 11, the upper first bus bar 2210a and the lower first bus bar 2210b extend along the x-crystal axis of the piezoelectric layer 100. Optionally, the third angle a3 between the normal direction F of the interdigital electrode 210 and the x-crystal axis of the piezoelectric layer 100 is between 0° and 15° (including clockwise and / or counterclockwise directions). At this time, the extension direction of the upper first bus bar 2210a and the lower first bus bar 2210b can be along the x-crystal axis of the piezoelectric layer 100, or can be set at an angle to the x-crystal axis of the piezoelectric layer 100. For example, the angle between the extension direction of the upper first bus bar 2210a and the lower first bus bar 2210b and the x-crystal axis of the piezoelectric layer 100 is between 0° and 15° (including clockwise and / or counterclockwise directions), etc.

[0093] 14 and 15 , the SAW resonator 10 further includes reflectors 400 located on both sides of the IDT 200. Here, the SAW resonator 10 includes two reflectors 400, one reflector 400 being disposed on each of two opposite sides of the IDT 200.

[0094] The reflector 400 includes a reflective grating 410 and two reflective busbar groups 420 connected to the reflective grating 410, referred to herein as an upper reflective busbar group 420a and a lower reflective busbar group 420b. Furthermore, the structure of the upper reflective busbar group 420a may be the same as or different from the structure of the lower reflective busbar group 420b.

[0095] Please continue to refer to Figure 14 or Figure 15. In the embodiment of the present application, each of the reflection busbar groups 420 includes at least two reflection busbars 421. Specifically, the upper reflection busbar group 420a includes an upper first reflection busbar 4210a and an upper second reflection busbar 4211a, and the lower reflection busbar group 420b includes a lower first reflection busbar 4210b and a lower second reflection busbar 4211b. The upper first reflection busbar 4210a is connected to the upper second reflection busbar 4211a, and the lower first reflection busbar 4210b is connected to the lower second reflection busbar 4211b. Specifically, adjacent reflection busbars 421 in the same reflection busbar group 420 can also be connected by a connecting bar (not shown in the figure). Further, adjacent reflection busbars 421 can be connected at the ends or at positions other than the ends. For example, an end of the upper first reflective bus bar 4210a is connected to an end of the upper second reflective bus bar 4211a, and an end of the lower first reflective bus bar 4210b is connected to an end of the lower second reflective bus bar 4211b.

[0096] Optionally, the upper first reflective bus bar 4210a and the upper first bus bar 2210a are located on the same straight line, the upper second reflective bus bar 4211a and the upper second bus bar 2211a are located on the same straight line, the lower first reflective bus bar 4210b and the lower first bus bar 2210b are located on the same straight line, and the lower second reflective bus bar 4211b and the lower second bus bar 2211b are located on the same straight line.

[0097] As shown in Figure 14 or Figure 15 , the two ends of each reflective grating 410 are connected to the upper first reflective busbar 4210a and the lower first reflective busbar 4210b, respectively. As shown in Figure 14 , in one embodiment of the present application, no mass block is provided on the reflective grating 410. As shown in Figure 15 , in another embodiment of the present application, a mass block 300 is provided on the reflective grating 410. Furthermore, a line connecting (the center of) the mass blocks 300 near the upper reflective busbar group 420a is parallel to the upper first reflective busbar 4210a; a line connecting (the center of) the mass blocks 300 near the lower reflective busbar group 420b is parallel to the lower first reflective busbar 4210b.

[0098] As shown in Figure 15, further, the line connecting the mass block 300 on the reflection grid 410 close to the upper reflection bus bar group 420a and the mass block 300 (center) on the interdigital electrode 210 close to the upper bus bar group 220a can be a straight line or a broken line; the line connecting the mass block 300 on the reflection grid 410 close to the lower reflection bus bar group 420b and the mass block 300 (center) on the interdigital electrode 210 close to the lower bus bar group 220b can also be a straight line or a broken line.

[0099] In an embodiment of the present application, the interdigital transducer includes a plurality of interdigital electrodes and two busbar groups connected to the interdigital electrodes. The busbars close to the interdigital electrodes in each busbar group are arranged at an angle to the normal of the interdigital electrodes, thereby suppressing the transverse mode. Furthermore, a mass block is provided at the end of the interdigital electrode, thereby reducing the speed of sound at the end of the interdigital electrode. Furthermore, each busbar group includes at least two busbars and adjacent busbars are connected, so that energy can be confined to the resonant cavity, energy leakage is suppressed, and the Q value is ultimately greatly improved.

[0100] Further, please refer to Figures 16 and 17, which are schematic diagrams comparing the transverse modal response and Q value of the surface acoustic wave resonator according to the embodiment of the present invention and the conventional surface acoustic wave resonator. The IDT in the surface acoustic wave resonator according to the embodiment of the present invention is shown in Figure 5 as an example, and the IDT in the conventional surface acoustic wave resonator is shown in Figure 18 as an example. The conventional IDT 500 includes interdigital electrodes 510 and bus bars 520 connected to the interdigital electrodes 510, wherein the bus bars 520 are parallel to the normal direction of the interdigital electrodes 510.

[0101] As shown in Figures 16 and 17 , where curve S1 represents the real part of the admittance curve of the surface acoustic wave resonator according to an embodiment of the present invention, curve S2 represents the real part of the admittance curve of a conventional surface acoustic wave resonator, curve S3 represents the Q value of the surface acoustic wave resonator according to an embodiment of the present invention, and curve S4 represents the Q value of a conventional surface acoustic wave resonator, it can be seen from Figures 16 and 17 that the surface acoustic wave resonator according to an embodiment of the present invention can effectively suppress the response of the transverse mode, and that the Q value of the surface acoustic wave resonator according to an embodiment of the present invention is generally at a high level within the passband, and energy leakage before and after the antiresonance frequency is effectively suppressed, resulting in a significant improvement in the Q value.

[0102] Furthermore, an embodiment of the present invention also provides a method for manufacturing a surface acoustic wave resonator. With reference to FIG. 1 to FIG. 15 and the above description of the surface acoustic wave resonator, the method for manufacturing the surface acoustic wave resonator specifically includes the following steps:

[0103] Step S10: providing a piezoelectric layer 100;

[0104] Step S11: forming an IDT 200 on the piezoelectric layer 100, wherein the IDT 200 includes a plurality of interdigital electrodes 210 and two bus bar groups 220 connected to the interdigital electrodes 210, wherein each bus bar group 220 includes at least two bus bars 221 and adjacent bus bars 221 are connected, and the bus bar 221 close to the interdigital electrode 210 in each bus bar group 220 is arranged at an angle to the normal F of the interdigital electrode 210; and

[0105] Step S12 : forming a mass block 300 at the end of the interdigital electrode 210 .

[0106] The step S11 may be executed before the step S12, or the step S11 and the step S12 may be executed simultaneously, or the step S12 may be executed before the step S11, or the step S11 and the step S12 may be executed alternately.

[0107] Furthermore, forming the IDT 200 on the piezoelectric layer 100 includes: forming a metal layer (not shown) on the piezoelectric layer 100; and etching the metal layer to form the IDT 200. In other embodiments of the present application, a patterned photoresist layer or dielectric layer may be first formed on the piezoelectric layer 100, wherein the patterned photoresist layer or dielectric layer exposes a portion of the piezoelectric layer 100; then, a metal layer is formed, wherein the metal layer covers the patterned photoresist layer or dielectric layer and the exposed piezoelectric layer 100; and then, the IDT 200 may be formed by peeling off the patterned photoresist layer or dielectric layer.

[0108] In one embodiment of the present application, the mass block 300 includes a metal mass layer (not shown in the figure); when the metal layer is etched to form the IDT 200, the metal mass layer is also formed. In this case, it can be considered that step S11 and step S12 are performed simultaneously.

[0109] In another embodiment of the present application, the mass block 300 may include multiple mass layers, for example, a metal mass layer and a dielectric mass layer located on the metal mass layer. For example, a metal layer is formed on the piezoelectric layer 100, and the metal layer is etched to simultaneously form the IDT 200 and the metal mass layer. Next, a dielectric layer is formed to cover the IDT 200 and the metal mass layer, and the dielectric layer is etched to form the dielectric mass layer.

[0110] In other embodiments of the present application, the mass block 300 may also include a multi-layer metal mass layer and / or a dielectric mass layer located below the interdigital transducer 200, and / or a multi-layer metal mass layer and / or a dielectric mass layer located above the interdigital transducer 200, which is not limited in the present application.

[0111] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A surface acoustic wave resonator, characterized in that: The surface acoustic wave resonator comprises: a piezoelectric layer and an interdigital transducer formed on the piezoelectric layer; The interdigital transducer includes a plurality of interdigital electrodes and two bus bar groups connected to the interdigital electrodes, wherein each of the bus bar groups includes at least two bus bars and adjacent bus bars are connected, the bus bars close to the interdigital electrodes in each of the bus bar groups are arranged at an angle to the normal direction of the interdigital electrodes, and a mass block is arranged at the end of the interdigital electrodes.

2. The surface acoustic wave resonator according to claim 1, characterized in that The bus bars close to the interdigital electrodes in each bus bar group are arranged at an angle to the x-crystal axis of the piezoelectric layer.

3. The surface acoustic wave resonator according to claim 1, characterized in that The two busbar groups have the same structure.

4. The surface acoustic wave resonator according to any one of claims 1 to 3, characterized in that Adjacent bus bars in each bus bar group are arranged in parallel or at an angle.

5. The surface acoustic wave resonator according to any one of claims 1 to 3, characterized in that The bus bar group further includes a connecting bar, and adjacent bus bars in each bus bar group are connected via the connecting bar.

6. The surface acoustic wave resonator according to any one of claims 1 to 3, characterized in that The maximum distance between adjacent bus bars in each bus bar group is greater than or equal to a period of the interdigital electrodes.

7. The surface acoustic wave resonator according to any one of claims 1 to 3, wherein: An angle between the bus bar close to the interdigital electrode in each bus bar group and the normal direction of the interdigital electrode is between 2° and 20° or between -20° and -2°.

8. The surface acoustic wave resonator according to any one of claims 1 to 3, wherein: The interdigitated electrodes only include true finger electrodes, the first ends of the true finger electrodes are connected to the bus bar group, and the second ends of the true finger electrodes are provided with the mass block; Alternatively, the interdigitated electrodes include real finger electrodes and dummy finger electrodes, the first ends of the real finger electrodes and the first ends of the dummy finger electrodes are respectively connected to different bus bar groups, and the second ends of the real finger electrodes and / or the second ends of the dummy finger electrodes are provided with the mass block.

9. The surface acoustic wave resonator according to any one of claims 1 to 3, wherein: The ratio of the length of the mass block to the period of the interdigitated electrodes is between 0.25 and 1, wherein the length of the mass block is the maximum dimension of the mass block in the extension direction of the interdigitated electrodes; the ratio of the width of the mass block to the width of the interdigitated electrodes is between 1.2 and 2, wherein the width of the mass block is the maximum dimension of the mass block in the normal direction of the interdigitated electrodes.

10. The surface acoustic wave resonator according to any one of claims 1 to 3, wherein: The surface acoustic wave resonator further includes reflectors located at two sides of the interdigital transducer.

11. The surface acoustic wave resonator according to any one of claims 1 to 3, wherein: The surface acoustic wave resonator further includes a substrate layer, a trap layer and / or a first dielectric layer located below the piezoelectric layer; and / or the surface acoustic wave resonator further includes a second dielectric layer covering the interdigital transducer.

12. The surface acoustic wave resonator according to any one of claims 1 to 3, characterized in that: An angle between the bus bar in the bus bar group close to the interdigital electrodes and the normal direction of the interdigital electrodes is equal to an energy flow angle of the surface acoustic wave resonator.

13. A method for manufacturing a surface acoustic wave resonator, characterized in that: The method for manufacturing the surface acoustic wave resonator comprises: providing a piezoelectric layer; An interdigital transducer is formed on the piezoelectric layer, the interdigital transducer comprising a plurality of interdigital electrodes and two bus bar groups connected to the interdigital electrodes, wherein each of the bus bar groups comprises at least two bus bars and adjacent bus bars are connected, and the bus bars close to the interdigital electrodes in each of the bus bar groups are arranged at an angle to the normal direction of the interdigital electrodes; and A mass is formed at the end of the interdigitated electrodes.

14. The method for manufacturing a surface acoustic wave resonator according to claim 13, wherein: Forming an interdigital transducer on the piezoelectric layer includes: forming a metal layer on the piezoelectric layer; and, The metal layer is etched to form the IDT.

15. The method for manufacturing a surface acoustic wave resonator according to claim 14, characterized in that: The mass block includes a metal mass layer; when the metal layer is etched to form the interdigital transducer, the metal mass layer is also formed.

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