Surface acoustic wave ridge waveguide and integrated device based on aluminum nitride film

Abstract

The present invention provides a surface acoustic wave ridge waveguide and an integrated device based on an aluminum nitride film. The surface acoustic wave waveguide of the present invention comprises at least a substrate and a piezoelectric film, wherein the piezoelectric film is arranged on the substrate, the width of the piezoelectric film is not less than the thickness of the piezoelectric film; the piezoelectric film comprises a piezoelectric material; and the piezoelectric film further comprises a ridge structure. The surface acoustic wave waveguide of the present invention presents approximately isotropy within the plane, and when the extension direction of the piezoelectric film is bent at an angle, it can ensure that the conduction mode of the surface acoustic wave does not change substantially, thereby reducing the conduction loss of the surface acoustic wave. The surface acoustic wave waveguide of the present invention is more conducive to obtaining a high-performance integrated acoustic circuit, and is preferably used to prepare basic components of integrated acoustic circuits such as SAW beam splitters and ring resonators.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance surface acoustic wave devices, and more specifically, to a surface acoustic wave waveguide and an integrated acoustic device using a composite substrate of a piezoelectric film having a ridge structure and silicon carbide as a substrate. Background Art

[0002] Surface acoustic wave (SAW) is a mechanical wave whose energy is concentrated on the surface of the substrate material and propagates completely along the surface. Thanks to the advantages of relatively small device size, low transmission loss, simple transducer preparation and stable spectrum characteristics, SAW devices are widely used in today's wireless communications and sensing fields. With the development of the new generation of mobile communications (5G&6G) and the Internet of Things, the requirements for SAW devices are rapidly increasing, such as the hope that it can have a smaller device size, higher operating frequency, higher temperature stability, larger bandwidth, etc.

[0003] In traditional SAW devices based on piezoelectric substrates (such as lithium niobate and lithium tantalate), the SAW beams are relatively wide in the working state, and the aperture of the interdigital electrodes is generally larger than ten or even dozens of times the SAW wavelength. Under the traditional design framework, this wide beam can ensure the effective working bandwidth of the device and reduce the insertion loss of the device. However, it also brings some unfavorable factors, such as: 1) The wider beam is prone to crosstalk between adjacent beams, reducing the signal processing quality of the device; 2) The device area is increased, which is not conducive to further miniaturization; 3) The wide beam SAW is difficult to bend, which makes traditional surface acoustic wave devices only able to manipulate SAW in a single transmission direction, limiting the space for SAW devices to develop in the direction of multifunctionality, high integration, and high-density analog signal processing. Summary of the invention

[0004] The present invention aims to provide a surface acoustic wave waveguide and an integrated acoustic device based on an AlN piezoelectric film substrate with high acoustic impedance.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A surface acoustic wave waveguide, the surface acoustic wave waveguide at least comprises a substrate and a piezoelectric film, the piezoelectric film is arranged on the substrate, the width of the piezoelectric film is not less than the thickness of the piezoelectric film; the piezoelectric film comprises a piezoelectric material; the piezoelectric film further comprises a ridge structure. In the present invention, the thickness of the piezoelectric film refers to the height of the piezoelectric film on the substrate; the width of the piezoelectric film refers to the maximum width of the projection of the piezoelectric film on the substrate.

[0007] According to an embodiment of the present invention, the piezoelectric material is AlN.

[0008] According to an embodiment of the present invention, the thickness of the substrate is 0.1-1 mm, for example, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm.

[0009] According to an embodiment of the present invention, the substrate is selected from at least one of SiC, diamond and sapphire, and is preferably single crystal SiC.

[0010] According to an embodiment of the present invention, since the surface acoustic wave is mainly concentrated on the surface of the piezoelectric film and propagates, the thickness of the piezoelectric film is not greater than the wavelength of the surface acoustic wave. Exemplarily, the thickness of the piezoelectric film is not greater than 10 μm, for example, 0.1 μm-10 μm, and for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm.

[0011] According to an embodiment of the present invention, the width of the piezoelectric film is greater than or equal to the thickness of the piezoelectric film, for example, 0.1-20μm or 0.1-10μm, for example, 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm.

[0012] Exemplarily, the width of the piezoelectric film is equal to the thickness of the piezoelectric film, for example, 0.1-10 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm.

[0013] According to an embodiment of the present invention, the extension direction of the piezoelectric film is the projection of the piezoelectric film on the substrate, and the surface acoustic wave is transmitted along the extension direction of the piezoelectric film.

[0014] Preferably, the projection is at least one of a linear structure, a curved structure or a ring structure.

[0015] According to an embodiment of the present invention, the curved structure includes at least one bend.

[0016] Preferably, the bending angle of the bend is 30°-90°, for example, 90°. The bending angle refers to the angle value of the extension direction of the piezoelectric film caused by the bending in the extension direction of the piezoelectric film. When the surface acoustic wave is transmitted along the extension direction of the piezoelectric film, the transmission of the surface acoustic wave also changes with the bending angle.

[0017] Preferably, the bend includes at least one arc, and the bending radius of the arc is greater than or equal to 1 μm, such as 1-100 μm, 2-100 μm, and for example 1 μm, 2 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm.

[0018] Exemplarily, the projection of the piezoelectric film on the substrate has, for example, Figure 2 (a) or Figure 5 The curve structure shown in (a) comprises two identical bends, and the bend comprises two arcs, and the bends and arcs have the meanings as described above.

[0019] Exemplarily, the projection of the piezoelectric film on the substrate is a Y-shaped structure, and the Y-shaped structure has, for example, Figure 2 (b) or Figure 6 The structure shown in (a) includes 4 completely identical bends, each of which includes 2 arcs, and the bends and arcs have the meanings as described above.

[0020] Exemplarily, the projection of the piezoelectric film on the substrate is an annular structure, wherein the radius of the annular structure is greater than or equal to 1 μm, for example, 1-100 μm, 2-100 μm, and for example, 1 μm, 2 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm. Exemplarily, the annular structure has, for example, Figure 2 The structure shown in (c).

[0021] According to an embodiment of the present invention, the cross section of the ridge structure is a trapezoid, a triangle, a rectangle, a square, preferably a trapezoid. Preferably, the trapezoid can be a trapezoid known in the art, such as an isosceles trapezoid.

[0022] According to a preferred embodiment of the present invention, the piezoelectric film has a ridge structure, the height of the piezoelectric film is the height of the ridge structure, and the width of the piezoelectric film is the width of the ridge structure. In the present invention, the height of the ridge structure refers to the height of the cross section of the ridge structure, and the width of the ridge structure refers to the length of the lower side of the cross section of the ridge structure.

[0023] According to an embodiment of the present invention, the piezoelectric film can be deposited on the surface of the substrate by a method known in the art, which is not specifically limited in the present invention, as long as the piezoelectric film can be obtained, for example, by MOCVD, MBE and magnetron sputtering lamp deposition.

[0024] According to an embodiment of the present invention, the ridge structure can be obtained by etching the surface of the piezoelectric film by a method known in the art, and the present invention does not make any specific limitation, as long as the ridge structure can be obtained.

[0025] According to an embodiment of the present invention, the surface acoustic wave waveguide further comprises interdigitated electrodes, which are arranged on the upper surface of the piezoelectric film. Preferably, the interdigitated electrodes surround the surface of the ridge structure, preferably surround the entire upper surface of the ridge structure.

[0026] According to an embodiment of the present invention, the interdigital electrodes are periodically arranged on the upper surface of the piezoelectric film along the extension direction of the piezoelectric film.

[0027] According to an embodiment of the present invention, the interdigital electrodes may be any interdigital electrodes known in the art, as long as they can provide surface acoustic waves. Figure 3 The structure shown.

[0028] According to an exemplary embodiment of the present invention, the interdigitated electrodes at least include an excitation electrode and a bus bar, and the bus bar is disposed between the excitation electrode and the piezoelectric film. In the present invention, the excitation electrode can be any electrode known in the art, as long as it can convert the input signal into an acoustic surface wave.

[0029] According to an exemplary aspect of the present invention, the bus bar includes a first bus bar and a second bus bar.

[0030] Preferably, the first bus bar is connected to the excitation electrode, and the second bus bar is connected to the ground.

[0031] Preferably, the first bus bar and the second bus bar are arranged on the upper surface of the piezoelectric film at intervals.

[0032] According to an exemplary solution of the present invention, the first bus bar includes at least one first finger electrode, one end of the first finger electrode is connected to the first bus bar, and the other end is connected to the upper surface of the piezoelectric film.

[0033] According to an exemplary solution of the present invention, the second bus bar includes at least one second finger electrode, one end of the second finger electrode is connected to the second bus bar, and the other end is connected to the upper surface of the piezoelectric film.

[0034] According to an exemplary solution of the present invention, the first finger electrode and the second finger electrode are arranged on the upper surface of the piezoelectric film with an interval.

[0035] According to an exemplary solution of the present invention, the interval between any two adjacent first finger electrodes is one period of the interdigital electrodes.

[0036] According to an exemplary solution of the present invention, the second finger electrode has the same structure as the first finger electrode.

[0037] According to an exemplary solution of the present invention, the first bus bar is arranged on the substrate parallel to the piezoelectric film, and the first finger electrode is perpendicular to the piezoelectric film and surrounds the surface of the ridge structure of the piezoelectric film.

[0038] According to an exemplary embodiment of the present invention, the second bus bar is arranged on the substrate parallel to the piezoelectric film, the second finger electrode is perpendicular to the piezoelectric film, and surrounds the surface of the ridge structure of the piezoelectric film, preferably surrounds the entire upper surface of the ridge structure.

[0039] According to an embodiment of the present invention, the operating frequency range of the surface acoustic wave waveguide is 1 GHz to 10 GHz.

[0040] According to an embodiment of the present invention, the effective operating bandwidth of the surface acoustic wave waveguide is not less than 40%.

[0041] According to an exemplary solution of the present invention, when the width of the piezoelectric film is 1 μm, the effective working bandwidth of the surface acoustic wave waveguide is not less than 40%, for example, 46.15%.

[0042] According to an exemplary solution of the present invention, when the width of the piezoelectric film is 0.5 μm, the effective working bandwidth of the surface acoustic wave waveguide is not less than 70%, for example, 72.2%.

[0043] According to an embodiment of the present invention, the theoretical transmittance of the surface acoustic wave waveguide is at least 90%, preferably above 95%, for example 100% when turning at a small angle. Preferably, the small angle turning refers to the size of the bending radius when the piezoelectric film is a curved structure.

[0044] The present invention also provides the application of the surface acoustic wave waveguide in the field of integrated acoustic circuits, preferably used as a basic element of the integrated acoustic circuit.

[0045] According to an embodiment of the present invention, the basic elements of the integrated acoustic circuit are selected from SAW beam splitters and ring resonators.

[0046] The present invention also provides a SAW beam splitter, which comprises the above-mentioned surface acoustic wave waveguide.

[0047] Preferably, in the surface acoustic wave waveguide, the piezoelectric film has a Y-shaped structure.

[0048] The present invention also provides a ring resonant cavity, which comprises the above-mentioned surface acoustic wave waveguide.

[0049] Preferably, in the surface acoustic wave waveguide, the piezoelectric film has a ring-shaped structure.

[0050] The beneficial effects of the present invention are as follows:

[0051] The surface acoustic wave waveguide of the present invention preferably uses single crystal SiC as a substrate, which has the advantages of stable chemical properties and a small lattice constant mismatch rate between the piezoelectric film and the piezoelectric film. The piezoelectric film (preferably AlN film) is deposited on the surface of the substrate, which has lower lattice defects and better piezoelectric performance. Since the sound velocity of the SiC substrate is higher than that of the piezoelectric film (preferably AlN film), the surface acoustic wave is mainly concentrated on the surface of the piezoelectric film (preferably AlN film) and propagates, thereby obtaining a high-performance surface acoustic wave waveguide of the present invention.

[0052] When the thickness of the piezoelectric film is in the micron level, the operating frequency of the surface acoustic wave waveguide of the present invention can reach several gigahertz, and can be effectively modulated with the change of the waveguide width. The surface acoustic wave waveguide of the present invention is single-mode operation (supporting only quasi-Rayleigh mode transmission), and has a wide operating bandwidth (not less than 40%). The surface acoustic wave exhibits excellent surface acoustic wave transmission efficiency (up to 100%) during the transmission process of the surface acoustic wave waveguide of the present invention.

[0053] The surface acoustic wave waveguide of the present invention is approximately isotropic in the plane, and when the extension direction of the piezoelectric film is bent, the conduction mode of the surface acoustic wave can be ensured to be substantially unchanged, thereby reducing the conduction loss of the surface acoustic wave. The surface acoustic wave waveguide of the present invention is more conducive to obtaining a high-performance integrated acoustic circuit, and is preferably used to prepare basic components of integrated acoustic circuits such as SAW beam splitters and ring resonators. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagrams showing the structure of the surface acoustic wave waveguide of the present invention, (a) is a top view of the surface acoustic wave waveguide, and (b) is a cross-sectional view of the surface acoustic wave waveguide.

[0055] Figure 2 Schematic diagrams of the surface wave waveguide of the present invention are shown, including (a) a waveguide with a curved structure, (b) a waveguide with a Y-shaped structure, and (c) a ring-shaped waveguide.

[0056] Figure 3 Schematic diagram showing the interdigitated electrodes of the present invention.

[0057] Figure 4 The transmission spectrum of a waveguide with a straight structure is shown.

[0058] Figure 5 The transmission spectrum of the surface wave guide based on the curved structure is shown.

[0059] Figure 6The transmission spectrum of a beam splitter based on a surface wave guide with a Y-shaped structure is shown.

[0060] Figure 7 The energy diagram of the resonant cavity based on the ring-structured surface wave guide and the quality factor at the resonant frequency are shown. DETAILED DESCRIPTION

[0061] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0062] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0063] Example 1

[0064] like Figure 1 As shown, it is a schematic diagram of the surface acoustic wave (SAW) waveguide structure of this embodiment, and the SAW waveguide includes from top to bottom: an AlN piezoelectric film (dark gray part) and a SiC single crystal substrate (light gray part), and the AlN piezoelectric film is a ridge structure. Figure 1 In (a), A represents the cutting direction of the AlN piezoelectric film, and the corresponding cross-sectional view is shown in Figure 1 In (b), the ridge structure is an isosceles trapezoid, wherein the length 1 of the lower side of the trapezoid is the width of the piezoelectric film, and the height of the trapezoid is the thickness of the piezoelectric film.

[0065] In a specific embodiment of the present invention, the thickness of the piezoelectric film is not more than 10 μm, for example, 0.1 μm-10 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm.

[0066] In a specific embodiment of the present invention, the width of the piezoelectric film is greater than or equal to the thickness of the piezoelectric film, for example, 0.1-20μm or 0.1-10μm, for example, 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm.

[0067] In a specific embodiment of the present invention, the projection of the piezoelectric film on the substrate has, for example, Figure 2 In the curve structure shown in (a), the curve includes two identical bends, the bends include two arcs, the bending angle of the bends is 90°, and the bending radius R of the arc is 1 μm.

[0068] In a specific embodiment of the present invention, the projection of the piezoelectric film on the substrate is a Y-shaped structure, and the Y-shaped structure has, for example, Figure 2 The structure shown in (b) includes 4 completely identical bends, each of which includes 2 arcs. The bending angle of the bend is 90°, and the bending radius R of the arc is 1 μm.

[0069] The SAW waveguide of this embodiment is also provided with interdigital electrodes, such as Figure 3 In the black structure shown, in order to efficiently excite surface acoustic waves in the waveguide, the interdigitated electrodes are arranged on the upper surface of the piezoelectric film and at least surround the portion of the ridge structure 9, preferably the entire upper surface. Since the ridge structure 9 adopts AlN piezoelectric material, the microwaves applied by the interdigitated electrodes can be converted into mechanical waves and transmitted in the piezoelectric film in the form of surface acoustic waves. In this embodiment, the interdigitated electrodes include an excitation electrode and a bus bar. The excitation electrode is connected to the input end of the radio frequency signal and converts the microwaves at the input end into surface acoustic waves. The bus bar includes a first bus bar 12 and a second bus bar 11 which are parallel to each other, and their widths are both 2μm; the first bus bar 12 is connected to the radio frequency signal input end, and the second bus bar 11 is grounded. A plurality of first finger electrodes 4 are arranged on the first bus bar 12; a plurality of second finger electrodes 3 are arranged on the second bus bar electrode 11, and the first finger electrodes 4 and the second finger electrodes 3 are arranged in sequence. The distance 5 between any two adjacent second finger electrodes 4 (ie, the distance between adjacent first finger electrodes 3 ) is one period. The interdigitated electrodes are periodically arranged along the extension direction of the piezoelectric film.

[0070] The width 6 of the first finger electrode 4 is 0.4 μm, and the overlapping length of the first finger electrode 4 and the second finger electrode 3 on the piezoelectric film is the upper side length 2 of the trapezoid. The thickness of the interdigital electrode is 0.1 μm. Figure 3 The periodic direction of the middle finger electrodes is the Y direction, ie, the extension direction of the piezoelectric film.

[0071] In this embodiment, AlN piezoelectric film is selected to make the surface acoustic wave propagate along the Y direction. Figure 3 In (a), B refers to the tangent direction of the waveguide.

[0072] The AlN piezoelectric film of this embodiment is prepared by MOCVD method, and the ridge structure of this embodiment is obtained by etching the AlN piezoelectric film. The length direction of the ridge structure is parallel to the length direction of the interdigital electrodes.

[0073] The surface acoustic wave waveguide based on AlN in this embodiment uses SiC material as the substrate, which can localize the surface acoustic wave energy well inside the piezoelectric film, especially the ridge structure. Therefore, the present invention uses the AlN single crystal film and SiC substrate structure that are approximately isotropic in the plane to obtain the surface acoustic wave waveguide, which can confine the surface acoustic wave inside or near the ridge structure and guide the surface acoustic wave to be efficiently transmitted along the extension direction of the ridge structure.

[0074] The ridge waveguide of this embodiment has a wider operating frequency, the operating frequency range is 1 GHz to 10 GHz, and can be changed with the change of the lower side length 1 of the trapezoid.

[0075] Embodiment 2-4

[0076] The structures of the surface acoustic wave waveguides of Examples 2-4 are basically the same as those of Example 1, except that the widths of the piezoelectric films are 1 μm, 0.75 μm, and 0.5 μm, respectively.

[0077] Figure 4 The transmittance spectrum of the SAW waveguide of Example 2-4, in which the waveguide width of 0.5μm, the waveguide width of 0.75μm, and the waveguide width of 1μm respectively represent the transmittance of the SAW waveguide of Example 2-4. When the width of the piezoelectric film is 1μm, the operating frequency of the waveguide is between 3GHz and 4.8GHz; the effective working bandwidth is 46.15%; as the waveguide width decreases, its operating frequency and bandwidth can be effectively improved. When the waveguide width is 0.5μm, the SAW in the frequency band of 3.6GHz to 8.8GHz has a transmission efficiency close to 100%; the effective working bandwidth is 72.2%.

[0078] Example 5

[0079] This embodiment adopts Figure 5 In the surface acoustic wave waveguide shown in (a), in this embodiment, the piezoelectric film is a ridge structure with a curved structure, such as Figure 5 As shown in (a), the ridge structure includes a bend, and the bend includes two bending angles of 90°, and the bending radii corresponding to the two bending angles of the bend are both 10μm; the width of the piezoelectric film is 0.5μm (i.e., corresponding to the lower side length of the trapezoid), and the thickness of the piezoelectric film is 0.3μm; the surface acoustic wave is emitted from the input port #1 in the Rayleigh mode and is transmitted to the output port #2 along the extension direction of the piezoelectric film on the surface acoustic wave waveguide.

[0080] like Figure 5As shown in (b), when the surface acoustic wave is transmitted along the extension direction of the piezoelectric film on the surface acoustic wave waveguide of this embodiment, since the sound velocity of the AlN piezoelectric film is approximately isotropic in the plane, the surface acoustic wave SAW mode always remains the quasi-Rayleigh mode after the surface acoustic wave turns, and is still well localized inside the ridge structure. When working between 6.6GHz and 8.8GHz (relative bandwidth 28.6%), the waveguide can achieve full power transmission, S 21 Close to 1, that is, the transmittance is 100%.

[0081] Example 6

[0082] This embodiment adopts Figure 6 The Y-shaped beam splitter composed of the surface acoustic wave waveguide shown in (a) is a ridge structure with a Y-shaped structure, such as Figure 6 As shown in (a), the ridge structure includes a Y-shaped beam splitting bend, and the bending radius of the beam splitting bend is also set to 10μm. The width of the piezoelectric film is 0.5μm (i.e., the length of the lower side of the trapezoid), and the thickness of the piezoelectric film is 0.3μm; the surface acoustic wave is transmitted from the input port #1 to the bend in the Rayleigh mode, and is divided into a first acoustic wave and a second acoustic wave, wherein the first acoustic wave is transmitted to the output port #2 along the extension direction of the piezoelectric film on the surface acoustic wave waveguide; the second acoustic wave is transmitted to the output port #3 along the extension direction of the piezoelectric film on the surface acoustic wave waveguide.

[0083] from Figure 6 It can be seen that when operating between 6.6 GHz and 8.8 GHz (relative bandwidth 28.6%), the power output from the two output ports #2 and #3 is exactly the same (S 21 and S 31 Completely consistent), which is basically close to 50% of the sound wave energy flowing in from input port #1.

[0084] Example 7

[0085] This embodiment adopts Figure 2 The SAW ring resonator constructed by the ring structure shown in (c), wherein the width of the piezoelectric film is 0.5 microns, the thickness of the piezoelectric film is 0.3 microns, and the ridge structure is a ring structure with a radius of 80 μm.

[0086] The SAW whispering gallery modes (WGMs) in the resonator are excited by interdigitated electrodes placed on the waveguide, and the interdigitated electrodes are the same as those in Example 1. The free spectral range (FSR) between the two resonant modes is 8.625 MHz. In a ring resonator, the free spectral range between the whispering gallery modes is proportional to the group velocity (v g ), the theoretical relationship of the resonator circumference (L) is FSR = v g / L, where v g =4333.2m / s, L = 502.4μm. Figure 7 It can be seen that the SAW whispering gallery mode of the ring resonator of this embodiment has extremely high theoretical quality, its 3dB bandwidth is only 0.82kHz, and its Q value reaches 9.7×10 6 .

[0087] The above is a description of the exemplary embodiments of the present invention. However, the protection scope of the present application is not limited to the above embodiments. Any modification, equivalent substitution, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A surface acoustic wave waveguide, characterized in that: The surface acoustic wave waveguide at least includes a substrate and a piezoelectric film, the piezoelectric film is arranged on the substrate, the width of the piezoelectric film is not less than the thickness of the piezoelectric film; the piezoelectric film includes a piezoelectric material; The piezoelectric film further includes a ridge structure; The piezoelectric film has a ridge structure, the height of the piezoelectric film is the height of the ridge structure, the width of the piezoelectric film is the width of the ridge structure; the cross section of the ridge structure is at least one of a trapezoid, a triangle, a rectangle, and a square; The thickness of the piezoelectric film is not greater than the wavelength of the surface acoustic wave; the width of the piezoelectric film is greater than or equal to the thickness of the piezoelectric film; the thickness of the piezoelectric film is not greater than 10 μm, and the width of the piezoelectric film is 0.1-20 μm; The piezoelectric material is selected from AlN; the substrate is SiC; The extension direction of the piezoelectric film is the projection of the piezoelectric film on the substrate, and the surface acoustic wave is conducted along the extension direction of the piezoelectric film; the projection is at least one of a straight line structure, a curved line structure or a ring structure; the curved line structure includes at least one bend; the bending angle of the bend is 30°-90°; the bend includes at least one arc; the bending radius of the arc is greater than or equal to 1 μm; The operating frequency range of the surface acoustic wave waveguide is 1 GHz to 10 GHz; the effective operating bandwidth of the surface acoustic wave waveguide is not less than 40%; and the theoretical transmittance of the surface acoustic wave waveguide is at least 90% when turning at a small angle.

2. The surface acoustic wave waveguide according to claim 1, characterized in that: The thickness of the substrate is 0.1-1 mm.

3. The surface acoustic wave waveguide according to claim 1, characterized in that: The width of the piezoelectric film is 0.1-10 μm.

4. The surface acoustic wave waveguide according to claim 1, characterized in that: The bending radius of the arc is 1-100 μm.

5. The surface acoustic wave waveguide according to claim 4, characterized in that: The bending radius of the arc is 2-100 μm.

6. The surface acoustic wave waveguide according to claim 1, characterized in that: The surface acoustic wave waveguide further comprises interdigital electrodes, and the interdigital electrodes are arranged on the upper surface of the piezoelectric film; The interdigitated electrodes are surrounded on the surface of the ridge structure; The interdigital electrodes are periodically arranged on the upper surface of the piezoelectric film along the extending direction of the piezoelectric film.

7. The surface acoustic wave waveguide according to claim 6, characterized in that: The interdigitated electrodes surround the entire upper surface of the ridge structure.

8. The surface acoustic wave guide according to any one of claims 1 to 7 is used as a basic element in the field of integrated acoustic circuits.

9. A SAW beam splitter, comprising the surface acoustic wave waveguide according to any one of claims 1 to 7.

10. A ring resonant cavity, comprising the surface acoustic wave waveguide according to any one of claims 1 to 7.

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