A sound wave resonator and filter

Abstract

The present invention belongs to the field of surface acoustic wave technology. The present invention provides an acoustic wave resonator and a filter. The acoustic wave resonator includes a piezoelectric substrate, a functional layer and a temperature compensation layer stacked in sequence; the functional layer includes an interdigital transducer and a reflector; the acoustic wave resonator also includes an elliptical metal ring, which is arranged above the interdigital transducer and has a first interval with the plane where the surface of the interdigital transducer is located. The present invention creates different sound speed zones in the gap area of ​​the interdigital transducer by arranging an elliptical metal ring with adjustable geometric and dimensional features above the interdigital transducer of TC‑SAW, thereby effectively suppressing stray modes, preventing lateral energy leakage, and improving the waveguide capability and the quality factor of the resonator.

Description

Technical Field

[0001] The invention belongs to the field of surface acoustic waves and relates to an acoustic wave resonator and a filter. Background Art

[0002] Surface acoustic wave (SAW) is an elastic wave that propagates along the surface of a solid, and its energy is mainly concentrated near the surface. SAW technology is widely used in wireless communications, sensors, filters and other fields. Surface acoustic wave resonator (SAWR) is an important structure and device for the widespread application of SAW technology, with the characteristics of high Q value, miniaturization, and low power consumption.

[0003] Traditional surface acoustic wave resonators are composed of piezoelectric materials, interdigital transducers (IDTs) and reflective gratings. IDTs are used to excite and detect SAWs, and reflective gratings are used to reflect SAWs to form a resonant cavity. The propagation of surface acoustic waves depends on the elastic constant and density of the material, and these two properties are affected by temperature, which leads to the fact that traditional SAWRs using lithium niobate (LiNbO3) as piezoelectric materials have greater temperature sensitivity, limiting their development.

[0004] To overcome this challenge, predecessors designed a 128°YX lithium niobate substrate, silicon dioxide (SiO2) as a temperature compensation layer, and buried the temperature-compensated surface acoustic wave (TC-SAW) resonator of the interdigital transducer. The thermal expansion coefficient of silicon dioxide is opposite to that of lithium niobate, which produces a compensation effect and reduces the impact of temperature changes on the resonator performance. This temperature compensation method has been widely studied since the 1980s and is currently commercially used in mobile communications.

[0005] Depending on the IDT metal used, the operating mode (main mode) of TC-SAW can be horizontal shear surface acoustic wave (SH-SAW) or Rayleigh surface acoustic wave. However, TC-SAW resonators often encounter multiple spurious modes, including lateral modes, main modes, and multiple mode types in which the main mode is coupled with other modes. The presence of these spurious modes will produce passband ripples and limit out-of-band suppression, thereby impairing the performance of the acoustic wave filter. In this regard, a certain suppression effect can be achieved by properly selecting the cutting angle of piezoelectric materials such as lithium niobate, optimizing the IDT thickness, or optimizing the thickness of the temperature compensation layer. However, due to the strong anisotropy of lithium niobate, it is not easy to completely eliminate the excitation of horizontal shear surface acoustic waves.

[0006] Therefore, it is still necessary to study and develop a new solution to mitigate the TC-SAW spurious mode in order to improve the acoustic performance of acoustic wave resonators and devices such as filters containing them, and promote their further development in practical applications. Summary of the invention

[0007] In view of the problems existing in the prior art, the object of the present invention is to provide an acoustic wave resonator and a filter. The acoustic wave resonator has a new structure. An elliptical metal ring with adjustable geometric and dimensional characteristics is arranged above the TC-SAW interdigital transducer, thereby creating different sound speed zones in the gap area of ​​the interdigital transducer, thereby effectively suppressing spurious modes, preventing lateral energy leakage, and improving the waveguide capacity and the quality factor of the resonator.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides an acoustic wave resonator, the acoustic wave resonator comprising a piezoelectric substrate, a functional layer and a temperature compensation layer stacked in sequence; the functional layer comprises an interdigital transducer and reflectors arranged opposite to each other on both sides of the interdigital transducer;

[0010] The acoustic wave resonator further includes an elliptical metal ring, which is disposed above the IDT and has a first interval with the plane where the surface of the IDT is located.

[0011] The present invention arranges an elliptical metal ring in a temperature-compensated surface acoustic wave resonator as a new optimized structure. Without changing the structure of the interdigital transducer, the elliptical metal ring is arranged above the interdigital transducer so that the positive projection of the elliptical metal ring to the functional layer is in the IDT region to play a modulation role, thereby creating different sound velocity zones in the gap region between the active region and the busbar in the interdigital transducer, which is conducive to suppressing the transverse mode. That is, by strategically arranging the elliptical metal ring, the adjustment of the sound wave velocity in the gap region is effectively achieved, and then a propagation mode with a transverse wave vector close to zero can be created in the active region of the resonator, and finally the excellent effects of improving the waveguide capability, suppressing the stray mode and improving the quality factor (Q value) of the resonator are obtained.

[0012] Specifically, the technical mechanism of the present invention involves the use of an elliptical metal ring made of dense metal, which can replicate the shape of the envelope function of the desired surface acoustic wave (SAW). The technical mechanism involves the shaping of the elliptical metal ring so that the electric field applied to the device is mainly used to excite the required main vibration mode, that is, this is achieved by limiting the vibration energy to a specific area of ​​the device body through the geometric shape characteristics of the elliptical metal ring. The technology relies on the relationship between the impulse response of the device acoustic waveform, the electrode geometry under the elliptical metal ring and its frequency response. The implementation of this technical mechanism lies not only in the use of an elliptical metal ring composed of dense heavy metal and its shape closely matches the expected SAW wave envelope, but also in the correct positioning and arrangement of the elliptical metal ring so that it can affect the propagation of the SAW according to the desired envelope function. At the same time, the density of the heavy metal, the geometry of the ring and the arrangement position need to work together to limit the vibration energy to a specific area of ​​the device. The use of heavy metal elliptical metal rings can provide a more powerful, effective and consistent means for controlling the vibration mode of the SAW, thereby improving the performance of the device. This approach helps mitigate the effects of lateral spurious modes, which are unwanted vibrations that can interfere with the desired primary vibration mode. By using an elliptical metal ring to shape the propagation of the SAW, a cleaner and more selective frequency response can be achieved.

[0013] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0014] As a preferred technical solution of the present invention, the interdigital transducer includes two busbars arranged opposite to each other; the two busbars are respectively connected with fingers, and the fingers extend toward the busbar on the opposite side but retain a gap with the busbar on the opposite side, so that the interdigital transducer includes an active area formed by alternating arrangement of fingers, and gap areas formed at both ends of the active area.

[0015] As a preferred technical solution of the present invention, in the orthographic projection to the functional layer, the center of the elliptical metal ring is arranged in the active area; in the extension direction parallel to the finger strip, the edge of the inner ellipse of the elliptical metal ring does not exceed the active area; the edge of the outer ellipse of the elliptical metal ring does not exceed the gap area.

[0016] As a preferred technical solution of the present invention, in the orthographic projection onto the functional layer, the center of the elliptical metal ring coincides with the center of the active area, and the major axis of the inner ellipse of the elliptical metal ring is parallel to the finger strip, and the length of the major axis of the inner ellipse is equal to the length of the active area.

[0017] As a preferred technical solution of the present invention, in the orthographic projection onto the functional layer and in the extension direction parallel to the busbar, the reflector is arranged relatively on both sides of the active area and the gap area, the edge of the inner ellipse of the elliptical metal ring does not exceed the active area, or exceeds the active area and covers the reflector, and the edge of the outer ellipse of the elliptical metal ring does not exceed the reflector.

[0018] In the present invention, the elliptical metal ring modulates the sound velocity in the gap region of the interdigital transducer, so its geometric shape and size characteristics need to match the interdigital transducer, especially should be adapted to the active region and the gap region. According to the actual design and needs, the placement of the elliptical metal ring, the semi-axis length (large radius) of the major axis of the inner ellipse and the outer ellipse and the semi-axis length (small radius) of the minor axis, the width of the elliptical metal ring, etc. should be reasonably selected and adjusted to achieve its structural effectiveness and ensure the effect of suppressing stray modes and reducing energy leakage.

[0019] It should be noted that due to the geometric shape characteristics of the elliptical metal ring, in the orthographic projection to the functional layer, the size of the gap between the elliptical metal ring and the busbar in the direction parallel to the extension of the finger bar, that is, the distance between the edge of the outer ellipse and the edge of the busbar, changes with the shape and size of the outer ellipse at a specific position. Moreover, in the direction parallel to the extension of the finger bar, the chord length of the inner ellipse of the elliptical metal ring is equal to the effective aperture length of the acoustic wave resonator. It can be seen that the effective aperture length changes with the shape and size of the inner ellipse at a specific position. When the center of the inner ellipse coincides with the center of the active area, and the two ends of the main axis of the inner ellipse reach the junction of the active area and the gap area (that is, the end of the finger bar), the effective aperture length reaches the maximum value, and the effective aperture length is equal to the semi-axis length of the main axis of the inner ellipse of the elliptical metal ring.

[0020] As a preferred technical solution of the present invention, the acoustic wave resonator further comprises an edge metal strip; the edge metal strip is arranged above the IDT and has a second interval with the plane where the surface of the IDT is located.

[0021] As a preferred technical solution of the present invention, in the orthographic projection to the functional layer, the center of the edge metal strip is arranged in the gap area; in the extension direction parallel to the busbar, the edge of one side of the edge metal strip is in contact with the edge of one side of the busbar; in the extension direction parallel to the finger strip, the edge of the edge metal strip does not exceed the gap area and does not contact the elliptical metal ring.

[0022] As a preferred technical solution of the present invention, in the extension direction parallel to the finger strip, the width of the edge metal strip is 0.5~1λ, λ is the wavelength of the surface acoustic wave, and is further preferably 0.7~0.75λ, which is the optimal range for achieving spurious-free frequency response.

[0023] As a preferred technical solution of the present invention, in the orthographic projection onto the functional layer and parallel to the extension direction of the busbar, the edge metal strip extends to the edge of the gap area, or exceeds the gap area and covers the reflector.

[0024] As a preferred technical solution of the present invention, the edge metal strip and the elliptical metal ring are arranged in the same plane, and the first interval is equal to the second interval.

[0025] In the present invention, the edge metal strip can assist the elliptical metal ring in modulating the sound velocity in the gap region of the IDT, so its size parameters need to match the IDT and the elliptical metal ring. The length, width and spacing of the edge metal strip and the elliptical metal ring should be reasonably selected and adjusted according to the actual design and needs to achieve the structural effectiveness and ensure the corresponding effect.

[0026] As a preferred technical solution of the present invention, the elliptical metal ring is arranged on the surface of the temperature compensation layer, or is embedded in the temperature compensation layer, or is completely buried in the temperature compensation layer.

[0027] As a preferred technical solution of the present invention, for the portion of the elliptical metal ring exposed outside the temperature compensation layer, the inner ellipse of the elliptical metal ring is filled with temperature compensation material and / or a heavy dielectric material is arranged outside the outer ellipse of the elliptical metal ring.

[0028] As a preferred technical solution of the present invention, the temperature compensation material is the same as the temperature compensation layer; the acoustic impedance of the dielectric material is different from that of the temperature compensation layer and the density is greater than that of the temperature compensation layer.

[0029] As a preferred technical solution of the present invention, the heavy dielectric material includes at least one of hafnium oxide, silicon nitride, barium strontium titanate, aluminum oxide or titanium dioxide.

[0030] In the present invention, the elliptical metal ring can be completely arranged on the surface of the temperature compensation layer, that is, the first interval is equal to the thickness of the temperature compensation layer; or it can be embedded in the temperature compensation layer and at least the top surface is exposed, or it can be completely buried in the temperature compensation layer without exposing any surface. For the elliptical metal ring exposed to the outside, it further includes an edge metal strip exposed to the outside in the same layer and plane, and the blank area at this level can be filled with dielectric material. The choice of dielectric material will affect the performance of the acoustic resonator, including its temperature stability and frequency response.

[0031] As a preferred technical solution of the present invention, in the orthographic projection onto the functional layer, the edge of the temperature compensation layer is reduced to the edge of the outer ellipse of the elliptical metal ring.

[0032] As a preferred technical solution of the present invention, the temperature elastic coefficient of the temperature compensation layer is opposite to that of the piezoelectric substrate; the density property of the temperature compensation layer is opposite to that of the elliptical metal ring; the material of the elliptical metal ring, the edge metal strip, the reflector and the interdigital transducer is the same.

[0033] As a preferred technical solution of the present invention, the material of the elliptical metal ring includes at least one of aluminum, copper, gold, tungsten, molybdenum or silver.

[0034] As a preferred technical solution of the present invention, the material of the temperature compensation layer includes silicon dioxide.

[0035] As a preferred technical solution of the present invention, the material of the piezoelectric substrate includes at least one of lithium niobate, lithium tantalate or quartz.

[0036] In the present invention, the temperature compensation layer and the elliptical metal ring have opposite density properties, which means that when the temperature compensation layer uses a material with a larger density, the metal material density of the elliptical metal ring should be smaller; when the metal material of the elliptical metal ring is a heavy metal with a larger density (such as the above-mentioned copper and gold, etc.), the temperature compensation layer should use a material with a smaller density, such as silicon dioxide.

[0037] As a preferred technical solution of the present invention, the interdigital transducer has 10 to 1000 IDT periods.

[0038] As a preferred technical solution of the present invention, the reflector has 10 to 30 pairs of reflection gratings.

[0039] It should be noted that the present invention does not impose any specific restrictions on the specific materials and structures of the traditional TC-SAW structure (piezoelectric material, interdigital transducer and reflector) in the acoustic wave resonator. It should be understood that the connotation of the present invention, that is, to set an elliptical metal ring in the TC-SAW that can adjust the sound velocity in the gap area, improve the waveguide capability, suppress stray modes and improve the resonator quality factor, is to follow the purpose of the present invention.

[0040] In a second aspect, the present invention provides a filter, wherein the filter comprises the acoustic wave resonator described in the first aspect.

[0041] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0042] The present invention arranges an elliptical metal ring with adjustable geometric and dimensional features above the interdigital transducer of the TC-SAW to change the acoustic wave velocity or dispersion characteristics in the gap area. The structure not only suppresses the stray mode, but also helps to confine the energy in the resonator, reduce lateral energy leakage, achieve no stray signal response and clearer signal output, and effectively improve the quality factor Q value. A higher Q value means lower insertion loss, which is widely applicable to high-frequency applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the three-dimensional structure of an acoustic wave resonator in the present invention is shown;

[0044] Figure 2 Shows Figure 1 A top view of an acoustic wave resonator;

[0045] Figure 3 Shows Figure 2 Enlarged view of the middle dashed area M1;

[0046] Figure 4 Shows Figure 3 A cross-sectional view along section line N1-N1;

[0047] Figure 5 Shows Figure 3 A cross-sectional view along the N2-N2 section line;

[0048] Figure 6 Shows Figure 5 Enlarged view of the middle dashed area M2;

[0049] Figure 7 A top view of another acoustic wave resonator of the present invention is shown;

[0050] Figure 8 Shows Figure 7 A magnified view of the middle dashed area M3;

[0051] Fig. 9 Shows Figure 8 A cross-sectional view along section line N3-N3;

[0052] Fig.10 A schematic diagram of the three-dimensional structure of another acoustic wave resonator in the present invention is shown;

[0053] Fig.11 Shows Fig.10 A top view of an acoustic wave resonator;

[0054] Fig.12 Shows Fig.11 Enlarged view of the middle dashed area M4;

[0055] Fig.13 Shows Fig.12 A cross-sectional view along section line N4-N4;

[0056] Fig.14 Shows Fig.13 Enlarged view of the middle dashed area M5;

[0057] Fig.15 A top view of another acoustic wave resonator of the present invention is shown;

[0058] Fig.16 Shows Fig.15 Enlarged view of the middle dashed area M6;

[0059] Fig.17 Shows Fig.16 A cross-sectional view along section line N5-N5;

[0060] Fig.18 A cross-sectional view of another acoustic wave resonator according to the present invention along the N5-N5 section line is shown;

[0061] Fig.19 A cross-sectional view of another acoustic wave resonator according to the present invention along the N5-N5 section line is shown;

[0062] Fig. 20 A cross-sectional view of another acoustic wave resonator according to the present invention along the N5-N5 section line is shown;

[0063] Fig.21 Shows Fig. 20 Enlarged view of the middle dashed area M7;

[0064] Fig. 22 A top view of another acoustic wave resonator of the present invention is shown;

[0065] Fig.23 Shows Fig. 22 A cross-sectional view along section line N6-N6;

[0066] Fig.24 A top view of another acoustic wave resonator of the present invention is shown;

[0067] Fig.25 Shows Fig.24 A cross-sectional view along section line N7-N7;

[0068] Fig.26 A top view of another acoustic wave resonator of the present invention is shown;

[0069] Fig. 27 Shows Fig.26 A cross-sectional view along section line N8-N8;

[0070] Fig.28A top view of another acoustic wave resonator of the present invention is shown;

[0071] Fig.29 Shows Fig.28 A cross-sectional view along section line N9-N9;

[0072] Fig.30 A top view of another acoustic wave resonator of the present invention is shown;

[0073] Fig.31 Shows Fig.30 Along N 10 -N 10 Cross-sectional view of the hatching line.

[0074] Fig.32 The effect of the elliptical metal ring on the resonator vibration curve is demonstrated.

[0075] In the figure: 10-piezoelectric substrate, 20-interdigital transducer, 21-busbar, 21A-first busbar, 21B-second busbar, 22-finger, 22A-first finger, 22B-second finger, 23-gap area, 23A-first gap area, 23B-second gap area, 24-active area, 30-reflector, 30A-first reflector, 30B-second reflector, 31-reflection grating busbar, 32-reflection grating strip, 40-temperature compensation layer, 41-temperature compensation material, 50-elliptical metal ring, 50A-partial elliptical metal ring closer to the second busbar, 50B-partial elliptical metal ring closer to the first busbar, 60-edge metal strip, 60A-first edge metal strip, 60B-second edge metal strip, 70-heavy dielectric material. DETAILED DESCRIPTION

[0076] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0077] In some specific embodiments, such as Figure 1 As shown, the present invention provides an acoustic wave resonator, the acoustic wave resonator comprises a piezoelectric substrate 10, a functional layer and a temperature compensation layer 40 which are stacked in sequence; the functional layer comprises an IDT 20 and a reflector 30 which is arranged opposite to each other on both sides of the IDT 20; the acoustic wave resonator further comprises an elliptical metal ring 50, the elliptical metal ring 50 is arranged above the IDT 20, and has a first interval g1>0 with the plane where the surface of the IDT 20 is located, such as Figure 6 shown.

[0078] In one embodiment, the piezoelectric substrate 10, the interdigital transducer 20, the reflector 30, and the temperature compensation layer 40 respectively have corresponding widths in the X direction (or the first dimension direction), corresponding lengths in the Y direction (or the second dimension direction), and corresponding thicknesses in the Z direction (or the third direction); the X direction, the Y direction, and the Z direction constitute a three-dimensional coordinate space.

[0079] In some specific embodiments, such as Figure 1 As shown, the IDT 20 includes two busbars 21 arranged opposite to each other; the two busbars 21 are respectively connected with fingers 22, and the fingers 22 extend toward the busbar 21 on the opposite side but keep a gap therebetween, so that the IDT 20 includes an active area 24 formed by the fingers 22 arranged alternately, and gap areas 23 formed at both ends of the active area 24. That is, the section where the fingers 22 are connected to the busbar 21 is the starting end, and the other end facing the busbar 21 on the opposite side is the end, and the end forms a gap with the busbar 21 on the opposite side. The area covered by the IDT 20 is the IDT area, which includes the busbar area covered by the busbar 21, the gap area 23, and the active area 24.

[0080] In one embodiment, if Figure 2 As shown, the busbar 21 includes a first busbar 21A and a second busbar 21B; the first busbar 21A and the second busbar 21B both extend along the X direction and are arranged relatively spaced apart in the Y direction; the first busbar 21A and the second busbar 21B have a length in the X direction and a width in the Y direction.

[0081] In one embodiment, if Figure 2 As shown, the first busbar 21A is connected to a first finger 22A, and the first finger 22A extends toward the second busbar 21B along the Y direction, but does not contact the second busbar 21B, forming a first gap area 23A, and the length of the first gap area 23A is w1. Figure 4 As shown; the second busbar 21B is connected to a second finger 22B, the second finger 22B extends along the Y direction toward the first busbar 21A, but does not contact the first busbar 21A, forming a second gap area 23B, the length of the second gap area 23B is w2, as shown Figure 5 As shown; the first finger 22A and the second finger 22B have a length in the X direction and a width in the Y direction; the area between the first gap region 23A and the second gap region 23B constitutes an active area 24, the length of which is w3, as shown Figure 4 and Figure 5As shown; the size of the first gap area 23A, the second gap area 23B and the active area 24 in the Y direction is the width; the first finger 22A and the second finger 22B are arranged alternately along the X direction and do not contact each other; along the X direction, the distance from the edge of a first finger 22A to the corresponding edge of the same side of the most adjacent second finger 22B is the length p1 of an IDT period, as shown in FIG. Figure 3 As shown, one IDT period is a pair of transducers, or a repeating unit.

[0082] In one embodiment, w1=w2.

[0083] In one embodiment, the number of IDT periods of the interdigital transducer 20 is 10 to 1000, for example, 10, 30, 50, 80, 100, 200, 300, 400, 500, 600, 700, 800, 900 or 1000, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0084] In some specific embodiments, such as Figure 1 and Figure 2 As shown, the reflectors 30 are arranged opposite to each other on both sides of the active area 24 and the gap area 23 .

[0085] In one embodiment, the reflectors 30 are arranged opposite to each other on both sides of the IDT 20 along the X direction to form a first reflector 30A and a second reflector 30B; Figure 8 and Fig. 9 As shown, the first reflector 30A and the second reflector 30B both include relatively arranged reflection grating busbars 31, the reflection grating busbars 31 extend along the X direction, and one side edge is in the same straight line with the side edge of the busbar 21 close to the finger bar 22; the two relatively opposite reflection grating busbars 31 are connected with reflection grating bars 32 extending along the Y direction, that is, the reflection grating bars 32 are arranged parallel to the finger bar 22; the reflection grating bars 32 are alternately arranged along the X direction and do not contact each other; along the X direction, the distance from the edge of a reflection grating bar 32 to the corresponding edge of the same side of the most adjacent reflection grating bar 32 is the length p2 of a reflection grating period; and a reflection grating period includes a pair of reflection grating bars 32.

[0086] In one embodiment, the first reflector 30A and the second reflector 30B respectively have 10 to 30 pairs of reflective grating bars 32, such as 10 pairs, 13 pairs, 15 pairs, 18 pairs, 20 pairs, 22 pairs, 24 pairs, 26 pairs, 28 pairs or 30 pairs, but are not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0087] In some specific embodiments, such as Figure 6 As shown, the dimension of the elliptical metal ring 50 in the Z direction is the thickness, which is denoted as h1; along the axial length direction of the elliptical metal ring 50 through the center, the distance between the outer ellipse and the inner ellipse is the width of the elliptical metal ring 50, which is denoted as d1. Figure 6 shown.

[0088] In one embodiment, in a plane defined by the X direction and the Y direction, the width d1 of the elliptical metal ring 50 remains constant.

[0089] In some specific embodiments, in the orthographic projection to the functional layer, the center of the elliptical metal ring 50 is disposed in the active area 24; along the Y direction, the edge of the inner ellipse of the elliptical metal ring 50 does not exceed the active area 24, and the edge of the outer ellipse of the elliptical metal ring 50 does not exceed the gap area 23. That is, Figure 3 and Figure 8 As shown, in the elliptical metal ring 50, the partial elliptical metal ring closer to the second busbar 21B is marked as 50A, and the partial elliptical metal ring closer to the first busbar 21A is marked as 50B. In the orthographic projection to the functional layer, along the Y direction, the distance between the edge of the outer ellipse of the partial elliptical metal ring 50A and the edge of the adjacent second busbar 21B is s1; the distance between the edge of the outer ellipse of the partial elliptical metal ring 50B and the edge of the adjacent first busbar 21A is s2; the distance between the edge of the inner ellipse of the partial elliptical metal ring 50A and the edge of the inner ellipse of the partial elliptical metal ring 50B is s3, s3 is the chord length of the inner ellipse of the elliptical metal ring 50 along the Y direction; then s1>0, s2>0 and s3≤w3.

[0090] In one embodiment, s1=s2.

[0091] In one embodiment, in the orthographic projection onto the functional layer, the center of the elliptical metal ring 50 coincides with the center of the active area 24, and the major axis of the inner ellipse of the elliptical metal ring 50 is parallel to the finger 22, and the length of the major axis is equal to the length of the active area 24, that is, at this time, s3=w3 at the position of the major axis.

[0092] In some specific embodiments, such as Figure 7As shown, in the orthographic projection to the functional layer, along the X direction, the edge of the inner ellipse of the elliptical metal ring 50 does not exceed the active area 24, or exceeds the active area 24 and covers the reflector 30, and the edge of the outer ellipse of the elliptical metal ring 50 does not exceed the reflector 30. That is, the chord length of the outer ellipse of the elliptical metal ring 50 along the X direction is less than or equal to the width of the interdigital transducer 20, or is greater than the width of the interdigital transducer 20 but less than or equal to the maximum distance between the edges of a pair of reflectors 30.

[0093] In some specific embodiments, such as Fig.10 As shown, the acoustic wave resonator further includes an edge metal strip 60; the edge metal strip 60 is disposed above the IDT 20 and has a second interval g2>0 with respect to the plane where the surface of the IDT 20 is located. Fig.14 shown.

[0094] In one embodiment, in the orthographic projection onto the functional layer, the center of the edge metal strip 60 is disposed in the gap area 23; in the extension direction parallel to the busbar 21, one side edge of the edge metal strip 60 is in contact with one side edge of the busbar 21; in the extension direction parallel to the finger strip 22, the edge of the edge metal strip 60 does not exceed the gap area 23 and does not contact the elliptical metal ring 50.

[0095] In one embodiment, if Figures 11 to 14 As shown, the edge metal strip 60 includes a first edge metal strip 60A and a second edge metal strip 60B; that is, in the orthographic projection to the functional layer, the edge of the first edge metal strip 60A is attached to the edge of the first busbar 21A and extends along the X direction; the edge of the second edge metal strip 60B is attached to the edge of the second busbar 21B and extends along the X direction; the dimension in the Y direction is the width, recorded as d2, and the dimension in the Z direction is the thickness, recorded as h2, as shown in FIG. Fig.14 As shown; along the Y direction, the distance between the first edge metal strip 60A and the edge of the outer ellipse of the partial elliptical metal ring 50B is s5, and the distance between the second edge metal strip 60B and the edge of the outer ellipse of the partial elliptical metal ring 50A is s4, then s4>0, s5>0, such as Fig.12 shown.

[0096] In one embodiment, s4=s5.

[0097] In one embodiment, the width d2 of the first edge metal strip 60A and the second edge metal strip is 0.5-1λ, for example, 0.5λ, 0.52λ, 0.54λ, 0.56λ, 0.58λ, 0.6λ, 0.62λ, 0.64λ, 0.66λ, 0.68λ, 0.7λ, 0.705λ, 0.71λ, 0.715λ, 0.72λ, 0.725λ, 0.73λ, 0.735λ, 0.74λ, 0.75λ, 0.76λ, 0.77λ, 0.78λ, 0.79λ, 0.80λ, 0.81λ, 0.82λ, 0.83λ, 0.84λ, 0.85λ, 0.86λ, 0.87λ, 0.88λ, 0.89λ, 0.90λ, 0.91λ, 0.92λ, 0.93λ, 0.94λ, 0.95λ, 0.96λ, 0.97λ, 0.98λ, 0.9 ...9λ, 0.99λ, 0.99λ, 0.99λ, 0.99λ, 0.99λ, λ, 0.74λ, 0.745λ, 0.75λ, 0.78λ, 0.8λ, 0.82λ, 0.83λ, 0.85λ, 0.88λ, 0.9λ, 0.92λ, 0.95λ, 0.98λ or 1λ, etc., λ is the wavelength of the surface acoustic wave, and is further preferably 0.7~0.75λ, which is the optimal range for achieving spurious-free frequency response, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0098] In one embodiment, the width d2 of the first edge metal strip 60A and the second edge metal strip are the same.

[0099] In some specific embodiments, such as Fig.15 As shown, in the orthographic projection to the functional layer, along the X direction, the edge metal strip 60 extends to the edge of the gap area 23, or exceeds the gap area 23 and covers the reflector 30. That is, the size of the first edge metal strip 60A and the second edge metal strip 60B in the X direction is a length, which is less than or equal to the width of the IDT 20, or greater than the width of the IDT 20 but less than or equal to the maximum distance between the edges of a pair of reflectors 30.

[0100] In one embodiment, the lengths of the first edge metal strip 60A and the second edge metal strip 60B are the same and are equal to the maximum chord length of the outer ellipse of the elliptical metal ring 50 in the X direction.

[0101] In one embodiment, the edge metal strip 60 and the elliptical metal ring 50 are arranged in the same plane, and the first interval g1 is equal to the second interval g2, that is, g1=g2.

[0102] In one embodiment, g1=g2=0.01~0.1λ, for example, it can be 0.01λ, 0.02λ, 0.03λ, 0.04λ, 0.05λ, 0.06λ, 0.07λ, 0.08λ, 0.09λ or 0.1λ, etc., preferably 0.015~0.09λ, and further preferably 0.03~0.06λ. It is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0103] In some specific embodiments, the elliptical metal ring 50 is disposed on the surface of the temperature compensation layer 40 (eg Figures 1 to 17 ), or embedding the temperature compensation layer 40 (as shown Fig.18 and Fig.19 ), or completely burying the temperature compensation layer 40 (as shown Fig. 20 and Fig.21 as shown).

[0104] In one embodiment, for the portion of the elliptical metal ring 50 exposed outside the temperature compensation layer 40, the temperature compensation material 41 (such as Fig. 22 and Fig.23 ) and / or a heavy dielectric material 70 (such as Figure 24 to Figure 27 as shown).

[0105] In one embodiment, the temperature compensation material 41 is the same as the temperature compensation layer 40 ; the acoustic impedance of the heavy dielectric material 70 is different from that of the temperature compensation layer 40 and the density is greater than that of the temperature compensation layer 40 .

[0106] In one embodiment, the heavy dielectric material 70 includes at least one of hafnium oxide, silicon nitride, barium strontium titanate, aluminum oxide, or titanium dioxide.

[0107] In one embodiment, if Figure 28 to Figure 31 As shown, in an orthographic projection onto the functional layer, the edge of the temperature compensation layer 40 is reduced to the edge of the outer ellipse of the elliptical metal ring 50 .

[0108] In some specific embodiments, the temperature elastic coefficient of the temperature compensation layer 40 is opposite to that of the piezoelectric substrate 10; the density properties of the temperature compensation layer 40 are opposite to those of the elliptical metal ring 50; the material of the elliptical metal ring 50, the edge metal strip 60, the reflector 30 and the interdigital transducer 20 is the same.

[0109] In one embodiment, the material of the elliptical metal ring 50 includes at least one of aluminum, copper, gold, tungsten, molybdenum or silver.

[0110] In one embodiment, the temperature compensation layer 40 is made of silicon dioxide.

[0111] In one embodiment, the material of the piezoelectric substrate 10 includes at least one of lithium niobate, lithium tantalate or quartz.

[0112] In some specific embodiments, the present invention provides a filter, wherein the filter contains the acoustic wave resonator provided in the above embodiment.

[0113] Example 1

[0114] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 100, such as Figures 1 to 6 As shown, in the acoustic wave resonator, the temperature compensation layer 40 covers the entire functional layer; the elliptical metal ring 50 is arranged on the surface of the temperature compensation layer 40 away from the functional layer and exposed to the air; in the positive projection to the functional layer, the center of the elliptical metal ring 50 coincides with the center of the interdigital transducer 20, and the main axis of the inner ellipse of the elliptical metal ring 50 coincides with the main axis of the outer ellipse and is parallel to the Y direction, wherein the axis length of the main axis of the inner ellipse is equal to the length of the active area 24, so that the two end edges of the main axis of the inner ellipse It coincides with the edge of the active area 24, and the elliptical metal ring 50 has an appropriate width, so that the two end edges of the major axis of the outer ellipse are respectively located in the first gap area 23A and the second gap area 23B, and respectively retain the same size of gaps with the adjacent first busbar 21A and second busbar 21B; the axis length of the minor axis of the outer ellipse of the elliptical metal ring 50 is equal to the width of the active area 24, so that the two end edges of the minor axis of the outer ellipse coincide with the edge of the active area 24; at this time, the elliptical metal ring 50 only covers the IDT area.

[0115] Example 2

[0116] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 200, such as Figures 7 to 9 As shown, the difference between the acoustic wave resonator and the acoustic wave resonator in Example 1 is that in the orthographic projection to the functional layer, the axis length of the secondary axis of the outer ellipse of the elliptical metal ring 50 exceeds the active area 24, one end edge coincides with the edge of one side of the first reflector 30A away from the interdigital transducer 20, and the other end edge coincides with the edge of one side of the second reflector 30B away from the interdigital transducer 20, so that the two end edges of the secondary axis of the inner ellipse of the elliptical metal ring 50 are respectively located in the first reflector 30A and the second reflector 30B; at this time, the elliptical metal ring 50 covers the IDT area and the reflector. Except for the above, other conditions are exactly the same as those in Example 1.

[0117] Example 3

[0118] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 300, such as Figures 10 to 14As shown, the difference between the acoustic wave resonator and the acoustic wave resonator in Example 1 is that it also includes the edge metal strip 60 provided in the above embodiment, specifically including a first edge metal strip 60A and a second edge metal strip 60B which are arranged in the same plane as the elliptical metal ring 50 and have equal thickness; the first edge metal strip 60A and the second edge metal strip 60B have appropriate widths so that both retain the same size gap with the elliptical metal ring 50; and the lengths of the first edge metal strip 60A and the second edge metal strip 60B are equal to the width of the active area 24. At this time, the edge metal strip 60 covers the gap area 23. Except for the above, other conditions are exactly the same as those in Example 1.

[0119] Example 4

[0120] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 400, such as Figures 15 to 17 As shown, the difference between the acoustic wave resonator and the acoustic wave resonator in Example 1 is that the elliptical metal ring 50 is the same as the acoustic wave resonator in Example 2, the edge metal strip 60 is based on the solution of the acoustic wave resonator in Example 3, and the length of the first edge metal strip 60A and the length of the second edge metal strip 60B are adjusted to be equal to the length of the secondary axis of the outer ellipse of the elliptical metal ring 50, that is, one end of the edge metal strip 60 coincides with the edge of one side of the first reflector 30A away from the interdigital transducer 20, and the other end edge coincides with the edge of one side of the second reflector 30B away from the interdigital transducer 20. At this time, the edge metal strip 60 covers the gap area 23 and the reflector 30.

[0121] Example 5

[0122] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 310, such as Fig.18 As shown, the acoustic wave resonator is based on the acoustic wave resonator in Example 3, and the difference from the acoustic wave resonator is that the elliptical metal ring 50 and the edge metal strip 60 are both half-embedded in the temperature compensation layer 40, and the unembedded part is exposed to the air. Except for the above, other conditions are exactly the same as those in Example 3.

[0123] Example 6

[0124] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 320, such as Fig.19 As shown, the acoustic wave resonator is based on the acoustic wave resonator in Example 3, and the difference from the acoustic wave resonator is that the elliptical metal ring 50 and the edge metal strip 60 are all embedded in the temperature compensation layer 40, and the unembedded top surface portion is exposed to the air. Except for the above, other conditions are exactly the same as those in Example 3.

[0125] Example 7

[0126] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 330, such as Fig. 20 and Fig.21 As shown, the acoustic wave resonator is based on the acoustic wave resonator in Example 3, and the difference from the acoustic wave resonator is that the elliptical metal ring 50 and the edge metal strip 60 are all buried in the temperature compensation layer 40, without any exposed part. Except for the above, other conditions are exactly the same as those in Example 3.

[0127] Example 8

[0128] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 301, such as Fig. 22 and Fig.23 As shown, the acoustic wave resonator is based on the acoustic wave resonator in Example 3, and the difference from the acoustic wave resonator is that the temperature compensation material 41 is filled in the inner ellipse of the elliptical metal ring 50, and the thickness of the temperature compensation material 41 is equal to the thickness h1 of the elliptical metal ring 50; the outer area of ​​the outer ellipse is exposed to the air. Except for the above, other conditions are exactly the same as those in Example 3.

[0129] Example 9

[0130] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 302, such as Fig.24 and Fig.25 As shown, the acoustic wave resonator is based on the acoustic wave resonator in Example 3, and the difference from the acoustic wave resonator is that a heavy dielectric material 70 is provided in the outer region of the outer ellipse of the elliptical metal ring 50, and the thickness of the heavy dielectric material 70 is equal to the thickness h1 of the elliptical metal ring 50. Except for the above, other conditions are exactly the same as those in Example 3.

[0131] Example 10

[0132] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 303, such as Fig.26 and Fig. 27 As shown, the acoustic wave resonator is based on the acoustic wave resonator in Example 3, and the difference from the acoustic wave resonator is that: the temperature compensation material 41 is filled in the inner ellipse of the elliptical metal ring 50, and the thickness of the temperature compensation material 41 is equal to the thickness h1 of the elliptical metal ring 50; at the same time, a heavy dielectric material 70 is arranged in the outer area of ​​the outer ellipse of the elliptical metal ring 50, and the thickness of the heavy dielectric material 70 is equal to the thickness h1 of the elliptical metal ring 50. Except for the above, other conditions are exactly the same as those in Example 3.

[0133] Embodiment 11

[0134] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 101, such as Fig.28 and Fig.29 As shown, the acoustic wave resonator is based on the acoustic wave resonator in Example 1, and the difference from the acoustic wave resonator is that in the orthographic projection to the functional layer, the edge of the temperature compensation layer 40 is reduced to the edge of the outer ellipse of the elliptical metal ring 50, and is in the same shape as the outer ellipse. Except for the above, other conditions are exactly the same as those in Example 3.

[0135] Example 12

[0136] This embodiment adopts an acoustic wave resonator provided by the above-mentioned embodiment, numbered 102, such as Fig.30 and Fig.31 As shown, the acoustic wave resonator is based on the acoustic wave resonator in Example 11, and the difference from the acoustic wave resonator is that: the temperature compensation material 41 is filled in the inner ellipse of the elliptical metal ring 50, and the thickness of the temperature compensation material 41 is equal to the thickness h1 of the elliptical metal ring 50; at the same time, a heavy dielectric material 70 is arranged in the outer area of ​​the outer ellipse of the elliptical metal ring 50, and the heavy dielectric material 70 covers the top surface of the elliptical metal ring 50. Except for the above, other conditions are exactly the same as those in Example 11.

[0137] Comparative Example 1

[0138] This comparative example adopts an acoustic wave resonator, numbered CP1, which does not contain the elliptical metal ring 50 compared to the acoustic wave resonator in Example 1. Except for the above, other conditions are exactly the same as those in Example 1.

[0139] Comparative Example 2

[0140] This comparative example adopts an acoustic wave resonator, numbered CP2, which, compared with the acoustic wave resonator in Example 3, does not contain the elliptical metal ring 50, but only has the edge metal strip 60. Except for the above, other conditions are exactly the same as those in Example 1.

[0141] Fig.32 The effect of adding an elliptical metal ring on the vibration curve of the acoustic wave resonator obtained in the embodiment of the present invention is shown. It can be seen that the vibration distribution follows the shape of the elliptical metal ring, in which most of the vibration is concentrated in the center of the resonator, and the vibration decreases when moving away from the center in two directions.

[0142] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0143] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0144] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An acoustic wave resonator, characterized in that: The acoustic wave resonator comprises a piezoelectric substrate (10), a functional layer and a temperature compensation layer (40) which are stacked in sequence; the functional layer comprises an interdigital transducer (20) and reflectors (30) arranged opposite to each other on two sides of the interdigital transducer (20); The acoustic wave resonator further comprises an elliptical metal ring (50), the elliptical metal ring (50) being arranged above the interdigital transducer (20) and having a first gap g1 with the plane where the surface of the interdigital transducer (20) is located; The interdigital transducer (20) comprises two busbars (21) arranged opposite to each other; the two busbars (21) are respectively connected to fingers (22), the fingers (22) extending towards the busbar (21) on the opposite side but leaving a gap therebetween, so that the interdigital transducer (20) comprises an active region (24) formed by alternately arranging the fingers (22), and gap regions (23) formed at both ends of the active region (24); The busbar (21) comprises a first busbar (21A) and a second busbar (21B); the first busbar (21A) and the second busbar (21B) both extend along the X direction and are arranged at a relative interval in the Y direction; the first busbar (21A) is connected to a first finger bar (22A), the first finger bar (22A) extends along the Y direction toward the second busbar (21B) but does not contact the second busbar (21B), forming a first gap area (23A), the size of the first gap area in the Y direction is w1; the second busbar (21B) is connected to a second finger bar (22B), the second finger bar (22B) extends along the Y direction toward the first busbar (21A) but does not contact the first busbar (21A), forming a second gap area (23B), the size of the second gap area (23B) in the Y direction is w2; the first finger bar (22A) has the same size in the Y direction, the second finger bar (22B) has the same size in the Y direction, and w1=w2; In an orthographic projection onto the functional layer, the center of the elliptical metal ring (50) coincides with the center of the active area (24); In an extension direction parallel to the finger strip (22), the edge of the inner ellipse of the elliptical metal ring (50) does not exceed the active area (24), and the edge of the outer ellipse of the elliptical metal ring (50) does not exceed the gap area (23); the main axis of the inner ellipse of the elliptical metal ring (50) is parallel to the finger strip (22), and the length of the main axis is equal to the length of the active area (24).

2. The acoustic wave resonator according to claim 1, characterized in that In the orthographic projection onto the functional layer and in the extension direction parallel to the busbar (21), the reflector (30) is arranged opposite to each other on both sides of the active area (24) and the gap area (23), the edge of the inner ellipse of the elliptical metal ring (50) does not exceed the active area (24), or exceeds the active area (24) and covers the reflector (30), and the edge of the outer ellipse of the elliptical metal ring (50) does not exceed the reflector (30).

3. The acoustic wave resonator according to claim 1 or 2, characterized in that: The acoustic wave resonator further comprises an edge metal strip (60); the edge metal strip (60) is arranged above the interdigital transducer (20) and has a second gap g2 with the plane where the surface of the interdigital transducer (20) is located; In an orthographic projection onto the functional layer, the center of the edge metal strip (60) is arranged in the gap area (23); in an extension direction parallel to the busbar (21), an edge of one side of the edge metal strip (60) is in contact with an edge of one side of the busbar (21); in an extension direction parallel to the finger strip (22), an edge of the edge metal strip (60) does not extend beyond the gap area (23) and does not contact the elliptical metal ring (50); In an extension direction parallel to the finger strips (22), the width of the edge metal strip (60) is 0.5λ-1λ, where λ is the wavelength of the surface acoustic wave.

4. The acoustic wave resonator according to claim 3, characterized in that In an orthographic projection onto the functional layer and in an extension direction parallel to the busbar (21), the edge metal strip (60) extends to the edge of the gap region (23), or exceeds the gap region (23) and covers the reflector (30).

5. The acoustic wave resonator according to claim 3, characterized in that The edge metal strip (60) and the elliptical metal ring (50) are arranged in the same plane, and the first interval g1 is equal to the second interval g2.

6. The acoustic wave resonator according to claim 1 or 2, characterized in that: The elliptical metal ring (50) is arranged on the surface of the temperature compensation layer (40), or is embedded in the temperature compensation layer (40), or is completely buried in the temperature compensation layer (40); For the portion of the elliptical metal ring (50) exposed outside the temperature compensation layer (40), a temperature compensation material (41) is filled in the inner ellipse of the elliptical metal ring (50) and / or a heavy dielectric material (70) is arranged outside the outer ellipse of the elliptical metal ring (50); The temperature compensation material (41) is the same as the temperature compensation layer (40); the acoustic impedance of the heavy dielectric material (70) is different from that of the temperature compensation layer (40) and the density is greater than that of the temperature compensation layer (40); The heavy dielectric material (70) includes at least one of hafnium oxide, silicon nitride, barium strontium titanate, aluminum oxide or titanium dioxide.

7. The acoustic wave resonator according to claim 1 or 2, characterized in that: In an orthographic projection onto the functional layer, the edge of the temperature compensation layer (40) is reduced to the edge of the outer ellipse of the elliptical metal ring (50).

8. The acoustic wave resonator according to claim 3, characterized in that The temperature compensation layer (40) and the piezoelectric substrate (10) have opposite temperature elastic coefficients; the temperature compensation layer (40) and the elliptical metal ring (50) have opposite density properties; the elliptical metal ring (50), the edge metal strip (60), the reflector (30) and the interdigital transducer (20) are made of the same material; The material of the elliptical metal ring (50) includes at least one of aluminum, copper, gold, tungsten, molybdenum or silver; The material of the temperature compensation layer (40) includes silicon dioxide; The material of the piezoelectric substrate (10) includes at least one of lithium niobate, lithium tantalate or quartz.

9. A filter, characterized in that: A sonic resonator comprising any one of claims 1 to 8.

Images