Surface acoustic wave resonance device

Abstract

A surface acoustic wave resonance device comprises an interdigital electrode structure located on the surface of a piezoelectric layer; the dielectric structure is located on the piezoelectric layer and covers the interdigital electrode structure, the dielectric structure comprises a first dielectric layer, the first dielectric layer located on the first end region has a first thickness, the first dielectric layer located on the middle region has a second thickness, and the first dielectric layer located on the second end region has a third thickness; the first thickness is smaller than the second thickness, so that the sound velocity of sound waves excited by the interdigital electrode structure on the first end area is smaller than that on the middle area, the third thickness is smaller than the second thickness, so that the sound velocity of the sound waves excited by the interdigital electrode structure on the second end area is smaller than that on the middle area, and the surface acoustic wave resonance device excites a piston mode. And a high-order transverse parasitic mode is effectively suppressed.

Description

TECHNICAL FIELD

[0001] The utility model relates to a technical field of semiconductor, especially relate to a surface acoustic wave resonator. BACKGROUND

[0002] The radio frequency (RF) front-end chip of the wireless communication device includes power amplifier, antenna switch, radio frequency filter, multiplexer and low noise amplifier, etc. Among them, the radio frequency filter includes piezoelectric surface acoustic wave (SAW) filter, piezoelectric bulk acoustic wave (BAW) filter, micro-electro-mechanical system (MEMS) filter, integrated passive device (IPD) filter, etc.

[0003] The quality factor value (Q value) of the surface acoustic wave resonator is higher, and the surface acoustic wave resonator is used to manufacture the radio frequency filter with low insertion loss and high out-of-band rejection, that is, the surface acoustic wave resonator is the mainstream radio frequency filter used in the wireless communication device such as mobile phone and base station.

[0004] However, the performance of the existing surface acoustic wave resonator needs to be improved. UTILITY MODEL CONTENT

[0005] The technical problem solved by the utility model is to provide a surface acoustic wave resonator to improve the performance of the surface acoustic wave resonator.

[0006] To solve the above technical problems, the utility model discloses a surface acoustic wave resonant device, include: base, the base surface includes the first bus area, first gap area, coincident area, second gap area and second bus area along the first direction arrangement, first gap area is located between first bus area and coincident area, second gap area is located between second bus area and coincident area, coincident area includes the first end area, intermediate area and second end area along the first direction arrangement, first end area and second end area are located intermediate area both sides respectively, intermediate layer on base, piezoelectric layer on intermediate layer, base and piezoelectric layer are located intermediate layer both sides, interdigital electrode structure on piezoelectric layer surface, the interdigital electrode structure includes first bus, second bus, a plurality of first electrode strip and a plurality of second electrode strip, a plurality of first electrode strip is connected with first bus, a plurality of second electrode strip is connected with second bus, a plurality of first electrode strip and a plurality of second electrode strip are parallel to the first direction and along the second direction arrangement, the first direction and the second direction are perpendicular to each other, first electrode strip and second electrode strip are alternately arranged, first bus is located on first bus area, second bus is located on second bus area, a plurality of first electrode strip is located on first gap area and coincident area, a plurality of second electrode strip is located on coincident area and second gap area, a plurality of first electrode strip and a plurality of second electrode strip on coincident area coincide along the second direction, dielectric structure on piezoelectric layer, the dielectric structure covers interdigital electrode structure, the dielectric structure includes first dielectric layer, the first dielectric layer on first end area has first thickness, the first dielectric layer on intermediate area has second thickness, the first dielectric layer on second end area has third thickness, the first thickness is less than the second thickness, so that the sound velocity of the acoustic wave excited by the interdigital electrode structure on the first end area is less than the sound velocity on the intermediate area, the third thickness is less than the second thickness, so that the sound velocity of the acoustic wave excited by the interdigital electrode structure on the second end area is less than the sound velocity on the intermediate area.

[0007] Optionally, the first dielectric layer top surface on the first end area is recessed relative to the first dielectric layer top surface on the intermediate area to form a plurality of first grooves, a plurality of the first grooves are arranged along the second direction, and each of the first grooves is located on the first electrode strip or the second electrode strip; the first dielectric layer top surface on the second end area is recessed relative to the first dielectric layer top surface on the intermediate area to form a plurality of second grooves, a plurality of the second grooves are arranged along the second direction, and each of the second grooves is located on the first electrode strip or the second electrode strip.

[0008] Optionally, each of the first grooves further extends onto the first gap region; and each of the second grooves further extends onto the second gap region.

[0009] Optionally, a top surface of the first dielectric layer on the first end region is recessed relative to a top surface of the first dielectric layer on the middle region to form a first groove, the first groove extending along the second direction; and a top surface of the first dielectric layer on the second end region is recessed relative to the top surface of the first dielectric layer on the middle region to form a second groove, the second groove extending along the second direction.

[0010] Optionally, the first grooves further extend onto the first gap region; and the second grooves further extend onto the second gap region.

[0011] Optionally, the first electrode strip includes a first finger on the first end region, a second finger on the middle region, and a third finger on the second end region, the first finger having a first width in the second direction, the second finger having a second width in the second direction, and the third finger having a third width in the second direction, the first width being greater than the second width, and the third width being greater than the second width; and the second electrode strip includes a fourth finger on the first end region, a fifth finger on the middle region, and a sixth finger on the second end region, the fourth finger having a fourth width in the second direction, the fifth finger having a fifth width in the second direction, and the sixth finger having a sixth width in the second direction, the fourth width being greater than the fifth width, and the sixth width being greater than the fifth width.

[0012] Optionally, the first end region has a seventh width in the first direction, a ratio of the seventh width to a wavelength of an acoustic wave excited by the interdigital electrode structure being in a range from 1:10 to 2:1; and the second end region has an eighth width in the first direction, a ratio of the eighth width to the wavelength of the acoustic wave excited by the interdigital electrode structure being in a range from 1:10 to 2:1.

[0013] Optionally, a thickness of the middle layer is in a range from 1:50 to 10:1 of a wavelength of an acoustic wave excited by the interdigital electrode structure.

[0014] Optionally, a thickness of the piezoelectric layer is in a range from 1:50 to 20:1 of a wavelength of an acoustic wave excited by the interdigital electrode structure.

[0015] Optionally, the first dielectric layer covers the interdigital electrode structure, the dielectric structure further comprising a second dielectric layer on a surface of the first dielectric layer.

[0016] Optionally, the medium structure further comprises a second medium layer, the second medium layer covers the interdigital electrode structure, and the first medium layer is located on a surface of the second medium layer.

[0017] Optionally, a material of the first medium layer comprises silicon nitride, silicon oxynitride or aluminum oxide.

[0018] Compared with the prior art, the technical scheme of the embodiment of the present application has the following beneficial effects:

[0019] In the surface acoustic wave resonant device provided by the technical scheme of the present application, a specific pattern is formed on the first medium layer on the interdigital electrode structure, so that the sound velocity of the sound wave excited by the interdigital electrode structure on the first end region is less than the sound velocity on the middle region, and the sound velocity of the sound wave excited by the interdigital electrode structure on the second end region is less than the sound velocity on the middle region, thereby exciting a piston mode, effectively suppressing a high-order transverse parasitic mode, and improving the quality factor (Q) of the surface acoustic wave resonant device. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 And Figure 2 is a structural schematic diagram of a surface acoustic wave resonant device;

[0021] Figures 3-4 is a structural schematic diagram of the surface acoustic wave resonant device of the first embodiment of the present application;

[0022] Figure 5 is a structural schematic diagram of the surface acoustic wave resonant device of the second embodiment of the present application;

[0023] Figure 6 is a structural schematic diagram of the surface acoustic wave resonant device of the third embodiment of the present application;

[0024] Figure 7 is a structural schematic diagram of the surface acoustic wave resonant device of another embodiment of the present application;

[0025] Figure 8 is a structural schematic diagram of the surface acoustic wave resonant device of another embodiment of the present application. DETAILED DESCRIPTION

[0026] It should be noted that in the present application, "surface", "upper", are used to describe the relative position relationship in space, and are not limited to whether direct contact.

[0027] As described in the background, the performance of the surface acoustic wave resonant device needs to be improved. Now a surface acoustic wave resonant device will be described and analyzed.

[0028] Figure 1 AndFigure 2 is a structural schematic diagram of a surface acoustic wave resonator device.

[0029] Please refer to Figure 1 and Figure 2 , Figure 1 is a top view structural schematic diagram omitting the protective layer, Figure 2 is Figure 1 is a cross-sectional structural schematic diagram along the EE1 direction in the surface acoustic wave resonator device, which comprises a substrate 100, an intermediate layer 101 on the substrate 100, a piezoelectric thin film 102 on the intermediate layer 101, an interdigital electrode structure 103 on the piezoelectric thin film 102, and a protective layer 104 on the interdigital electrode structure 103.

[0030] In the above-mentioned surface acoustic wave resonator device, the acoustic wave can excite a high-order transverse mode, and generate spurious waves between the resonant frequency and the anti-resonant frequency of the resonator, which significantly deteriorates the performance in the passband of the filter.

[0031] In order to solve the above-mentioned problems, the technical scheme of the present application provides a surface acoustic wave resonator device, which forms a specific pattern on the first dielectric layer on the interdigital electrode structure, so that the acoustic velocity of the acoustic wave excited by the interdigital electrode structure on the first end region is less than that on the intermediate region, and the acoustic velocity of the acoustic wave excited by the interdigital electrode structure on the second end region is less than that on the intermediate region, thereby exciting a piston mode, effectively suppressing a high-order transverse parasitic mode, and improving the quality factor (Q) of the surface acoustic wave resonator device.

[0032] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0033] Figures 3-4 is a structural schematic diagram of a surface acoustic wave resonator device according to the first embodiment of the present application.

[0034] Please refer to Figures 3-4 , Figure 3 is a top view structural schematic diagram omitting the dielectric structure, Figure 4 is Figure 3A schematic diagram of a cross-sectional structure along the direction of FF1, the surface acoustic wave resonator device comprising: a substrate 200, the surface of the substrate 200 comprising a first bus region L1, a first gap region G1, an overlap region I, a second gap region G2 and a second bus region L2 arranged along a first direction X, the first gap region G1 being located between the first bus region L1 and the overlap region I, the second gap region G2 being located between the second bus region L2 and the overlap region I, the overlap region I comprising a first end region a1, a middle region c and a second end region a2 arranged along the first direction X, the first end region a1 and the second end region a2 being located on both sides of the middle region c respectively; an intermediate layer 201 located on the substrate 200; a piezoelectric layer 202 located on the intermediate layer 201, the substrate 200 and the piezoelectric layer 202 being located on both sides of the intermediate layer 201; an interdigital electrode structure located on the surface of the piezoelectric layer 202, the interdigital electrode structure comprising a first bus 2033, a second bus 2034, a plurality of first electrode strips 2031 and a plurality of second electrode strips 2032, a plurality of the first electrode strips 2031 being connected with the first bus 2033, a plurality of the second electrode strips 2032 being connected with the second bus 2034, a plurality of the first electrode strips 2031 and a plurality of the second electrode strips 2032 being parallel to the first direction X and arranged along a second direction Y, the first direction X and the second direction Y being perpendicular to each other, the first electrode strips 2031 and the second electrode strips 2032 being arranged alternately, the first bus 2033 being located on the first bus region L1, the second bus 2034 being located on the second bus region L2, a plurality of the first electrode strips 2031 being located on the first gap region G1 and the overlap region I, a plurality of the second electrode strips 2032 being located on the overlap region I and the second gap region G2, a plurality of the first electrode strips 2031 and a plurality of the second electrode strips 2032 on the overlap region I having an overlap along the second direction Y; a dielectric structure located on the piezoelectric layer 202, the dielectric structure covering the interdigital electrode structure, the dielectric structure comprising a first dielectric layer 204, the first dielectric layer 204 located on the first end region a1 having a first thickness h1, the first dielectric layer 204 located on the middle region c having a second thickness h2, the first dielectric layer 204 located on the second end region a2 having a third thickness h3, the first thickness h1 being smaller than the second thickness h2, so that the speed of the acoustic wave excited by the interdigital electrode structure on the first end region a1 is smaller than the speed of the acoustic wave on the middle region c, the third thickness h3 being smaller than the second thickness h2, so that the speed of the acoustic wave excited by the interdigital electrode structure on the second end region a2 is smaller than the speed of the acoustic wave on the middle region c.

[0035] Here, by forming a specific pattern on the first dielectric layer 204 on the interdigital electrode structure, the sound speed of the acoustic wave excited by the interdigital electrode structure on the first end region a1 is less than the sound speed on the middle region c, and the sound speed of the acoustic wave excited by the interdigital electrode structure on the second end region a2 is less than the sound speed on the middle region c, thereby exciting a piston mode, effectively suppressing high-order transverse parasitic modes, and improving the quality factor (Q) of the surface acoustic wave resonator.

[0036] It should be noted that the acoustic wave has a first sound speed in the first dielectric layer 204, and the main mode has a second sound speed when the surface acoustic wave resonator is excited, and the first sound speed is greater than the second sound speed.

[0037] Specifically, the first end region a1 is located between the first gap region G1 and the middle region c, and the second end region a2 is located between the second gap region G2 and the middle region c.

[0038] It should be noted here that the first dielectric layer can be obtained by first forming a first dielectric material layer (not shown in the figure) on the piezoelectric layer 202, and then etching a groove on the first end region a1 or part of the first end region a1, so that the first thickness h1 is less than the second thickness h2. The formation of the first dielectric layer is only one of the more optimized solutions, and is not limited here.

[0039] In this embodiment, the top surface of the first dielectric layer 204 of the first end region a1 is recessed relative to the top surface of the first dielectric layer 204 on the middle region c to form a first groove 205, and the first groove 205 extends along the second direction Y; the top surface of the first dielectric layer 204 on the second end region a2 is recessed relative to the top surface of the first dielectric layer 204 on the middle region c to form a second groove 206, and the second groove 206 extends along the second direction Y.

[0040] In this embodiment, the first groove 205 also extends to the first gap region G1; and the second groove 206 also extends to the second gap region G2.

[0041] It should be noted here that, Figure 3 The positions of the first groove 205 and the second groove 206 are shown, and the first groove 205 and the second groove 206 can have various distribution forms to achieve the purpose of making the first thickness h1 less than the second thickness h2.

[0042] In another embodiment, the top surface of the first dielectric layer on the first end region is recessed relative to the top surface of the first dielectric layer on the middle region to form a first groove, but does not extend to the first gap region; the top surface of the first dielectric layer on the second end region is recessed relative to the top surface of the first dielectric layer on the middle region to form a second groove, but does not extend to the second gap region.

[0043] In yet another embodiment, the top surface of the first dielectric layer on the first end region is recessed relative to the top surface of the first dielectric layer on the middle region to form a plurality of first grooves, the plurality of first grooves being arranged along the second direction, each of the first grooves being located on the first electrode strip or the second electrode strip; the top surface of the first dielectric layer on the second end region is recessed relative to the top surface of the first dielectric layer on the middle region to form a plurality of second grooves, the plurality of second grooves being arranged along the second direction, each of the second grooves being located on the first electrode strip or the second electrode strip.

[0044] In yet another embodiment, the top surface of the first dielectric layer on the first end region is recessed relative to the top surface of the first dielectric layer on the middle region to form a plurality of first grooves, the plurality of first grooves being arranged along the second direction, each of the first grooves being located on the first electrode strip or the second electrode strip, and further extending to the first gap region; the top surface of the first dielectric layer on the second end region is recessed relative to the top surface of the first dielectric layer on the middle region to form a plurality of second grooves, the plurality of second grooves being arranged along the second direction, each of the second grooves being located on the first electrode strip or the second electrode strip, and further extending to the second gap region.

[0045] In the present embodiment, the center-to-center spacing L between adjacent first electrode strips and between adjacent second electrode strips in the second direction is the same. The acoustic wavelength excited by the interdigital electrode structure is equal to the center-to-center spacing L.

[0046] In this embodiment, the first electrode strip 2031 includes a first finger 2031a located on the first end region a1, a third finger 2031b located on the second end region a2, and a second finger 2031c located on the middle region c, the first finger a1 has a first width W1 in the second direction Y, the second finger 2031c has a second width W2 (not shown in the figure) in the second direction Y, and the third finger 2031b has a third width W3 in the second direction Y; the second electrode strip 2032 includes a fourth finger 2032a located on the first end region a1, a sixth finger 2032b located on the second end region a2, and a fifth finger 2032c located on the middle region c, the fourth finger 2032a has a fourth width W4 (not shown in the figure) in the second direction Y, the fifth finger 2032c has a fifth width W5 (not shown in the figure) in the second direction Y, and the sixth finger 2032b has a sixth width W6 (not shown in the figure) in the second direction Y.

[0047] In this embodiment, the first width W1 is equal to the second width W2, and the third width W3 is equal to the second width W2; the fourth width W4 is equal to the fifth width W5, and the sixth width W6 is equal to the fifth width W5.

[0048] In another embodiment, the first width W1 is greater than the second width W2, and the third width W3 is greater than the second width W2; the fourth width W4 is greater than the fifth width W5, and the sixth width W6 is greater than the fifth width W5.

[0049] In this embodiment, the first end region a1 has a seventh width W7 in the first direction X, and the ratio of the seventh width W7 to the wavelength of the acoustic wave excited by the interdigital electrode structure ranges from 1:10 to 2:1; the second end region a2 has an eighth width W8 in the first direction X, and the ratio of the eighth width W8 to the wavelength of the acoustic wave excited by the interdigital electrode structure ranges from 1:10 to 2:1.

[0050] In this embodiment, the ratio of the thickness d1 of the middle layer 201 to the wavelength of the acoustic wave excited by the interdigital electrode structure ranges from 1:50 to 10:1.

[0051] In this embodiment, the ratio of the thickness d2 of the piezoelectric layer 202 to the wavelength of the acoustic wave excited by the interdigital electrode structure ranges from 1:50 to 20:1.

[0052] In this embodiment, the medium structure only includes the first medium layer 204.

[0053] In this embodiment, the material of the first dielectric layer 204 includes silicon nitride, silicon oxynitride or aluminum oxide.

[0054] In this embodiment, the intermediate layer 201 is a bonding layer that bonds the substrate 200 and the piezoelectric layer 202.

[0055] In this embodiment, the material of the substrate 200 includes silicon, sapphire, spinel or silicon carbide; the material of the intermediate layer 201 includes silicon oxide, silicon oxynitride or silicon oxide containing a dopant, the dopant including one or both of carbon and fluorine; the material of the piezoelectric layer 202 includes lithium tantalate, lithium niobate, aluminum nitride or zinc oxide.

[0056] In another embodiment, the first dielectric layer covers the interdigital electrode structure, and the dielectric structure further includes: a second dielectric layer located on the surface of the first dielectric layer; the material of the second dielectric layer includes one or more of silicon dioxide, silicon oxycarbide and silicon oxyfluoride.

[0057] In yet another embodiment, the dielectric structure further includes: a second dielectric layer covering the interdigital structure, the first dielectric layer being located on the surface of the second dielectric layer; the material of the second dielectric layer includes one or more of silicon dioxide, silicon oxycarbide and silicon oxyfluoride.

[0058] Figure 5 is a structural schematic view of the surface acoustic wave resonator device of the second embodiment of the present application.

[0059] The main difference between this embodiment and the first embodiment is that:

[0060] In the first embodiment, the dielectric structure only includes the first dielectric layer, while in this embodiment, the dielectric structure includes the first dielectric layer and a second dielectric layer located on the surface of the first dielectric layer.

[0061] Please continue to refer to Figure 4 on the basis of Figure 5 , the dielectric structure further includes: a second dielectric layer 301 located on the surface of the first dielectric layer 204.

[0062] In this embodiment, the structure of the surface acoustic wave resonator device is the same as that of the first embodiment except the second dielectric layer 301, which will not be repeated here.

[0063] The material of the second dielectric layer 301 includes one or more of silicon dioxide, silicon oxycarbide and silicon oxyfluoride. The second dielectric layer 301 functions as a protective layer, which can effectively prevent corrosion of the interdigital electrode structure caused by external moisture and oxidation of the interdigital electrode structure.

[0064] In the embodiment, the second dielectric layer 301 has a conformality, that is, the thickness of the second dielectric layer 301 is uniform.

[0065] Figure 6 is a structural schematic diagram of the surface acoustic wave resonator device of another embodiment of the utility model.

[0066] The embodiment is different from the first embodiment in that the dielectric structure further comprises a second dielectric layer.

[0067] Please fill in Figure 4 on the basis of continuing to refer to Figure 6 , the dielectric structure further comprises a second dielectric layer 401, the second dielectric layer 401 covers the interdigital electrode structure, and the first dielectric layer 204 is located on a surface of the second dielectric layer 401.

[0068] In the embodiment, the structure of the surface acoustic wave resonator device is the same as that of the first embodiment except the second dielectric layer 401, and details are not repeated here.

[0069] The material of the second dielectric layer 401 comprises one or more of silicon dioxide, silicon oxycarbide and silicon oxyfluoride.

[0070] The second dielectric layer 401 plays a temperature compensation role, is conducive to improving a frequency temperature coefficient (TCF) of the surface acoustic wave resonator device, and improves stability and reliability of operation of the surface acoustic wave resonator device.

[0071] In the embodiment, a top surface of the second dielectric layer 401 is flat, that is, the first dielectric layer 204 is located on the flat surface.

[0072] Figure 7 is a structural schematic diagram of the surface acoustic wave resonator device of another embodiment of the utility model.

[0073] The main difference between the embodiment and the above-mentioned embodiments is that the distribution forms of the first groove and the second groove on the first dielectric layer are different, and except the first groove and the second groove, the rest please refer to Figure 3 and Figure 4 and related descriptions, and details are not repeated here.

[0074] In the embodiment, the top surface of the first dielectric layer 204 on the first end region a1 is recessed relative to the top surface of the first dielectric layer 204 on the middle region c to form a plurality of first grooves 505, the plurality of first grooves 505 are arranged along the second direction Y, each of the first grooves 505 is located on the first electrode strip 2031 or the second electrode strip 2032 and further extends to the first gap region G1; the top surface of the first dielectric layer 204 on the second end region a2 is recessed relative to the top surface of the first dielectric layer 204 on the middle region c to form a plurality of second grooves 506, the plurality of second grooves 506 are arranged along the second direction Y, each of the second grooves 506 is located on the first electrode strip 2031 or the second electrode strip 2032 and further extends to the second gap region G2.

[0075] In another embodiment, each of the first grooves can not extend to the first gap region, and each of the second grooves can not extend to the second gap region.

[0076] Figure 8 It is a structural schematic diagram of a surface acoustic wave resonator according to another embodiment of the utility model.

[0077] The main difference between the embodiment and the above-mentioned embodiments is that the width distribution of the first electrode strip and the second electrode strip.

[0078] The rest please refer to Figure 3 and Figure 4 and the related description, which will not be repeated here.

[0079] In the embodiment, the first electrode strip 6031 includes a first finger portion 6031a located on the first end region a1, a third finger portion 6031b located on the second end region a2, and a second finger portion 6031c located on the middle region c, the first finger portion 6031a has a first width w1 in the second direction Y, the second finger portion 6031c has a second width w2 in the second direction Y, and the third finger portion 6031b has a third width w3 (not shown in the figure) in the second direction Y; the second electrode strip 6032 includes a fourth finger portion 6032a located on the first end region a1, a sixth finger portion 6032b located on the second end region a2, and a fifth finger portion 6032c located on the middle region c, the fourth finger portion 6032a has a fourth width w4 (not shown in the figure) in the second direction Y, the fifth finger portion 6032c has a fifth width w5 in the second direction Y, and the sixth finger portion 6032b has a sixth width w6 in the second direction Y.

[0080] In the embodiment, the first width w1 is greater than the second width w2, the third width w3 is greater than the second width w2; the fourth width w4 is greater than the fifth width w5, and the sixth width w6 is greater than the fifth width w5.

[0081] Here, the widths of the first finger portion 6031a and the third finger portion 6031b are both greater than the width of the second finger portion 6031c, and the widths of the fourth finger portion 6032a and the sixth finger portion 6032b are both greater than the width of the fifth finger portion 6032c, further limiting the speed of sound on the first end region a1 and the second end region a2 to be less than the speed of sound on the middle region c, thereby more favorably exciting the piston mode of the surface acoustic wave resonator.

[0082] Although the utility model discloses as above, the utility model is not limited to this. Any person skilled in the art, without departing from the spirit and scope of the utility model, can make various changes and modifications, therefore the protection scope of the utility model should be the range that the claim defines accurately.

Claims

1. A surface acoustic wave resonator device, characterized by, The application relates to a surface acoustic wave device, comprising: a substrate, a surface of the substrate comprising a first bus region, a first gap region, an overlap region, a second gap region and a second bus region arranged along a first direction, the first gap region being located between the first bus region and the overlap region, the second gap region being located between the second bus region and the overlap region, the overlap region comprising a first end region, a middle region and a second end region arranged along the first direction, the first end region and the second end region being located on two sides of the middle region respectively; an intermediate layer located on the substrate; a piezoelectric layer located on the intermediate layer, the substrate and the piezoelectric layer being located on two sides of the intermediate layer; an interdigital electrode structure located on a surface of the piezoelectric layer, the interdigital electrode structure comprising a first bus, a second bus, a plurality of first electrode strips and a plurality of second electrode strips, the plurality of first electrode strips being connected with the first bus, the plurality of second electrode strips being connected with the second bus, the plurality of first electrode strips and the plurality of second electrode strips being parallel to the first direction and arranged along a second direction, the first direction and the second direction being perpendicular to each other, the first electrode strips and the second electrode strips being arranged alternately, the first bus being located on the first bus region, the second bus being located on the second bus region, the plurality of first electrode strips being located on the first gap region and the overlap region, the plurality of second electrode strips being located on the overlap region and the second gap region, the plurality of first electrode strips and the plurality of second electrode strips on the overlap region being overlapped along the second direction; 2. The SAW resonator device of claim 1, wherein, a dielectric structure located on the piezoelectric layer, the dielectric structure covering the interdigital electrode structure, the dielectric structure comprising a first dielectric layer, the first dielectric layer located on the first end region having a first thickness, the first dielectric layer located on the middle region having a second thickness, the first dielectric layer located on the second end region having a third thickness, the first thickness being smaller than the second thickness, so that a sound velocity of a sound wave excited by the interdigital electrode structure on the first end region is smaller than a sound velocity on the middle region, the third thickness being smaller than the second thickness, so that a sound velocity of a sound wave excited by the interdigital electrode structure on the second end region is smaller than a sound velocity on the middle region.

3. The SAW resonator device of claim 2, wherein, a top surface of the first dielectric layer on the first end region being recessed relative to a top surface of the first dielectric layer on the middle region to form a plurality of first recesses, the plurality of first recesses being arranged along the second direction, each of the first recesses being located on the first electrode strip or the second electrode strip; a top surface of the first dielectric layer on the second end region being recessed relative to the top surface of the first dielectric layer on the middle region to form a plurality of second recesses, the plurality of second recesses being arranged along the second direction, each of the second recesses being located on the first electrode strip or the second electrode strip. each of the first recesses further extending to the first gap region; each of the second recesses further extending to the second gap region.

4. The SAW resonator device of claim 1, wherein, The first medium layer top surface on the first end region is recessed relative to the first medium layer top surface on the middle region to form a first groove, the first groove extending along the second direction; the first medium layer top surface on the second end region is recessed relative to the first medium layer top surface on the middle region to form a second groove, the second groove extending along the second direction.

5. The SAW resonator device of claim 4, wherein, The first groove further extends to the first gap region; the second groove further extends to the second gap region.

6. The SAW resonator device of claim 1, wherein, The first electrode strip includes a first finger on the first end region, a second finger on the middle region, and a third finger on the second end region, the first finger having a first width in the second direction, the second finger having a second width in the second direction, the third finger having a third width in the second direction, the first width being greater than the second width, the third width being greater than the second width; the second electrode strip includes a fourth finger on the first end region, a fifth finger on the middle region, and a sixth finger on the second end region, the fourth finger having a fourth width in the second direction, the fifth finger having a fifth width in the second direction, the sixth finger having a sixth width in the second direction, the fourth width being greater than the fifth width, the sixth width being greater than the fifth width.

7. The SAW resonator device of claim 1, wherein, The first end region has a seventh width in the first direction, a ratio of the seventh width to a wavelength of an acoustic wave excited by the interdigital electrode structure ranging from 1:10 to 2:1; the second end region has an eighth width in the first direction, a ratio of the eighth width to the wavelength of the acoustic wave excited by the interdigital electrode structure ranging from 1:10 to 2:

1.

8. The SAW resonator device as claimed in claim 1, wherein, A ratio of a thickness of the middle layer to the wavelength of the acoustic wave excited by the interdigital electrode structure ranges from 1:50 to 10:

1.

9. The SAW resonator device as claimed in claim 1, wherein, A ratio of a thickness of the piezoelectric layer to the wavelength of the acoustic wave excited by the interdigital electrode structure ranges from 1:50 to 20:

1.

10. The SAW resonator device as claimed in claim 1, wherein, The first medium layer covers the interdigital electrode structure, the medium structure further comprising: a second medium layer on a surface of the first medium layer.

11. The SAW resonator device as claimed in claim 1, wherein, The medium structure further comprises: a second medium layer, the second medium layer covering the interdigital electrode structure, the first medium layer on a surface of the second medium layer.

12. The SAW resonator device as claimed in claim 1, wherein, A material of the first medium layer comprises silicon nitride, silicon oxynitride, or aluminum oxide.

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