Surface acoustic wave device

Abstract

The application relates to the technical field of wireless communication, and provides a surface acoustic wave device, which comprises a supporting substrate, a piezoelectric substrate and an interdigital transducer; the supporting substrate is made of sapphire material; the interdigital transducer comprises first interdigital electrodes, second interdigital electrodes, and oppositely arranged first bus bars and second bus bars; the first interdigital electrodes are spaced from the second interdigital electrodes and the second bus bars, and the first interdigital electrodes and the second interdigital electrodes are opposite in polarity; the arrangement direction of the first interdigital electrodes and the second interdigital electrodes is the sound wave propagation direction; wherein the sapphire is r-surface sapphire, the crystal arrangement of the r-surface sapphire is in the shape of a regular hexagonal prism, the growth axis of the r-surface sapphire is perpendicular to the bottom surface thereof, and the [2-1-1] crystal direction of the r-surface sapphire is perpendicular to the normal projection of the growth axis on the r-surface and parallel to the sound wave propagation direction. The surface acoustic wave device can realize higher frequency, higher reliability and higher power.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a surface acoustic wave device. Background Technology

[0002] Surface acoustic wave (SAW) devices, with their excellent acoustic and electrical properties, have been widely used in many important fields such as communications, medical, satellite, and transportation, becoming one of the indispensable core components in modern electronic devices. However, as electronic devices rapidly develop towards high-end, high-frequency, and high-reliability directions, traditional SAW devices, limited by the performance shortcomings of their substrates and structural materials, are gradually failing to meet the stringent performance requirements of high-end SAW products. Therefore, there is an urgent need to develop SAW devices with novel structures and substrate materials.

[0003] Multilayer bonded surface acoustic wave (SAW) devices have become a research hotspot and development trend in high-end SAW devices due to their numerous advantages, including large bandwidth, low insertion loss, low temperature drift, high power, and high out-of-band suppression. However, in the fabrication process of multilayer bonded structures, to achieve performance improvements such as high frequency and high reliability, high-velocity acoustic materials such as silicon, polycrystalline silicon, sapphire, and spinel are often introduced as substrates or intermediate layers. The introduction of such high-velocity acoustic materials leads to significant high-order clutter responses in the high-frequency band of the SAW device. These clutter responses severely degrade the harmonic characteristics of the filter, thereby affecting the overall stability and performance of the SAW device, becoming a key bottleneck restricting the application of multilayer bonded SAW devices in high-end fields.

[0004] Currently, most conventional multilayer bonded surface acoustic wave (SAW) devices use silicon as the substrate for fabrication. This is primarily due to silicon's low cost, mature fabrication process, and ease of integration with modern integrated circuit chips, making it widely used in low- to mid-range SAW devices. Meanwhile, to further improve the high-frequency performance, reliability, and power handling capacity of SAW devices, existing technologies have also emerged that use sapphire as the substrate and directly bond it to piezoelectric materials. Sapphire substrates offer significant performance advantages over silicon substrates, including high mechanical strength, excellent chemical stability, high thermal conductivity, superior crystal quality, mature fabrication process, excellent insulation properties, and high sound velocity. Sapphire-based SAW devices can better meet the application requirements of high frequency, high reliability, and high power, making them more suitable for high-end product scenarios.

[0005] However, neither silicon nor sapphire substrates can effectively solve the problem of high-order clutter response caused by the introduction of high-velocity materials in multilayer bonding structures. This problem has always seriously affected the harmonic characteristics of the filter and limited the further improvement of device performance. For silicon substrates, existing technologies usually change the crystal plane and crystal orientation of the silicon substrate (such as using the (111) plane of silicon and some applicable crystal orientations), or roughen the surface of the dielectric layer between the piezoelectric material and the silicon substrate to weaken the high-order clutter response through scattering. However, the surface roughening process of the dielectric layer is extremely complex and has strict requirements on the surface roughness and flatness at the nanometer level, which greatly increases the difficulty of the fabrication process and the production cost, and is not conducive to large-scale production.

[0006] While existing technologies offer insights into patterning sapphire substrates to suppress common noise, the patterning process is more complex than the roughening process for silicon substrates, resulting in poor process controllability, high production costs, and difficulty in achieving industrial application. Summary of the Invention

[0007] To address the shortcomings of the existing technologies, this invention proposes a surface acoustic wave (SAW) device to solve the problem of difficulty in suppressing high-order clutter responses in existing SAW devices.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] This invention provides a surface acoustic wave (SAW) device, comprising a supporting substrate, a piezoelectric substrate stacked and fixed to the surface of the supporting substrate, and an interdigital transducer disposed on the side of the piezoelectric substrate away from the supporting substrate. The supporting substrate is made of sapphire material and is bonded to the piezoelectric substrate. The interdigital transducer includes a first interdigital electrode, a second interdigital electrode, and a first busbar and a second busbar spaced apart and opposite to each other. The first interdigital electrode and the second interdigital electrode are disposed between the first busbar and the second busbar. The first interdigital electrode and the second interdigital electrode are arranged parallel to each other and intersecting. The end of the first interdigital electrode near the first busbar is fixed to the first busbar, and the end of the second interdigital electrode near the second busbar is fixed to the second busbar. The first interdigital electrode is spaced apart from the second interdigital electrode and the second busbar, and the polarities of the first interdigital electrode and the second interdigital electrode are opposite. The direction in which the first interdigital electrode and the second interdigital electrode are arranged is the direction of sound wave propagation.

[0010] The sapphire is a r-faceted sapphire, the crystal arrangement of the r-faceted sapphire is a regular hexagonal prism, the growth axis of the r-faceted sapphire is perpendicular to its bottom surface, and the [2-1-1] crystal orientation of the r-faceted sapphire is perpendicular to the orthogonal projection of the growth axis on the r-face and parallel to the direction of sound wave propagation.

[0011] Preferably, the piezoelectric substrate is made of at least one or more materials selected from quartz, lithium niobate, lithium tantalate, aluminum nitride, zinc oxide, and PZT.

[0012] Preferably, the interdigital transducer is made of one or more materials selected from copper, platinum, gold, iron, aluminum, nickel, titanium, chromium, molybdenum, and tantalum.

[0013] Preferably, both the first interdigital electrode and the second interdigital electrode are multilayer structures formed of titanium, aluminum, and titanium.

[0014] Preferably, the metallization ratio of both the first interdigital electrode and the second interdigital electrode is 0.4 to 0.8.

[0015] Preferably, the metallization ratio of both the first interdigital electrode and the second interdigital electrode is 0.5.

[0016] Preferably, the thickness of both the first interdigital electrode and the second interdigital electrode is 7% to 10% of the period length;

[0017] Wherein, along the direction of sound wave propagation, the gap between adjacent first interdigital electrodes and second interdigital electrodes is the gap width, and the total width of the electrode width of the first interdigital electrode or the second interdigital electrode and the gap width is the period length;

[0018] Defined as follows: the thickness of the first interdigital electrode is a, the gap width is b, and the period length is λ; and satisfying the following conditions:

[0019] λ = a + b.

[0020] Preferably, the thickness of both the first interdigital electrode and the second interdigital electrode is 8% of the period length.

[0021] Compared with related technologies, in the embodiments of the present invention, a piezoelectric substrate is sequentially stacked on a support substrate, and an interdigital transducer is grown on the piezoelectric substrate; the support substrate is made of sapphire material, and the support substrate and the piezoelectric substrate are bonded and fixed; the first interdigital electrode and the second interdigital electrode of the interdigital transducer are disposed between the first bus bar and the second bus bar; the first interdigital electrode and the second interdigital electrode are arranged in parallel and crosswise; the end of the first interdigital electrode near the first bus bar is fixed to the first bus bar, and the end of the second interdigital electrode near the second bus bar is fixed to the second bus bar; the first interdigital electrode is spaced apart from the second interdigital electrode and the second bus bar, and the first interdigital electrode and the second bus bar are respectively spaced apart. The polarity of the second interdigital electrode is opposite; the orientation of the first and second interdigital electrodes is the direction of sound wave propagation; the sapphire is r-faced sapphire, the crystal arrangement of the r-faced sapphire is a regular hexagonal prism, the growth axis of the r-faced sapphire is perpendicular to its bottom surface, the orthogonal projection of the growth axis on the r-face, and the [2-1-1] crystal orientation of the r-faced sapphire is perpendicular to the orthogonal projection of the growth axis on the r-face and parallel to the direction of sound wave propagation; thus, by using r-faced sapphire as a supporting substrate and bonding it to a piezoelectric substrate, the unique crystal orientation of the r-faced sapphire can be used to reduce the high-order clutter response and realize a surface acoustic wave device with higher frequency, higher reliability, and higher power. Attached Figure Description

[0022] The present invention will now be described in detail with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and more readily understood through the detailed description following the accompanying drawings. In the drawings:

[0023] Figure 1 A cross-sectional view of the surface acoustic wave device provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of the interdigital transducer of the surface acoustic wave device provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of a commonly used c-plane sapphire crystal structure;

[0026] Figure 4 A schematic diagram of the r-plane sapphire crystal structure of the surface acoustic wave device provided in an embodiment of the present invention;

[0027] Figure 5 Simulation diagram of admittance characteristics of surface acoustic wave devices using commonly used c-plane sapphire crystals;

[0028] Figure 6 Simulation diagram of the admittance characteristics of the r-plane sapphire crystal in the surface acoustic wave device provided in the embodiment of the present invention. Detailed Implementation

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0030] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Please see Figures 1-6As shown, this embodiment of the invention provides a surface acoustic wave (SAW) device 100. The SAW device 100 includes a supporting substrate 1, a piezoelectric substrate 2 stacked and fixed to the surface of the supporting substrate 1, and an interdigital transducer 3 disposed on the side of the piezoelectric substrate 2 away from the supporting substrate 1. The supporting substrate 1 is made of sapphire material, and the supporting substrate 1 is bonded and fixed to the piezoelectric substrate 2. The interdigital transducer 3 includes a first interdigital electrode 33, a second interdigital electrode 34, and a first busbar 31 and a second busbar 32 disposed at intervals and opposite to each other. The first interdigital electrode 33 and the second interdigital electrode 34 are disposed on the first busbar 31 and the second interdigital electrode 34. Between the second busbars 32; the first interdigital electrode 33 and the second interdigital electrode 34 are arranged parallel to each other and intersecting; the end of the first interdigital electrode 33 near the first busbar 31 is fixed to the first busbar 31, and the end of the second interdigital electrode 34 near the second busbar 32 is fixed to the second busbar 32; the first interdigital electrode 33 is spaced apart from the second interdigital electrode 34 and the second busbar 32 respectively, and the polarities of the first interdigital electrode 33 and the second interdigital electrode 34 are opposite; the direction in which the first interdigital electrode 33 and the second interdigital electrode 34 are arranged is the direction of sound wave propagation. By definition, the plane where the interdigital transducer 3 is located is the xy plane, the direction of sound wave propagation is the x-direction, the direction perpendicular to the direction of sound wave propagation is the y-direction, the direction perpendicular to the xy plane is the z-direction, and the z-direction is the thickness direction of the interdigital transducer 3.

[0033] Specifically, the support substrate 1 uses sapphire (Al2O3) material as its core, which can provide rigid support, suppress acoustic wave energy leakage, and improve device performance and reliability. Due to the poor acoustic impedance matching between sapphire and the piezoelectric substrate 2, the acoustic impedance mismatch causes total internal reflection of bulk waves propagating to the substrate, confining the acoustic wave energy to the surface of the piezoelectric substrate 2 and significantly reducing energy leakage. Sapphire has high thermal conductivity, low dielectric loss, and good high-temperature stability. When the RF surface acoustic wave device is operating, the interdigitated electrodes generate Joule heat, and the lattice vibration of the piezoelectric substrate 2 also generates heat. The sapphire support substrate 1 can quickly conduct heat away, avoiding electrode electromigration and piezoelectric material performance degradation caused by excessive internal device temperature. Simultaneously, the low dielectric loss reduces the transmission loss of RF signals in the support substrate 1, making it suitable for high-frequency RF applications.

[0034] Specifically, the piezoelectric substrate 2 is the core functional layer for realizing electro-acoustic / acoustic-electric conversion and is the carrier for the generation and propagation of surface acoustic waves.

[0035] Specifically, by arranging the first interdigital electrode 33 and the second interdigital electrode 34 of the interdigital transducer 3 (IDT) in a cross configuration along the direction of sound wave propagation, precise spatial and electrical matching is provided for the excitation, propagation, and reception of surface acoustic waves (SAWs), which is fundamental to achieving efficient electroacoustic signal conversion. Arranging the first interdigital electrode 33 and the second interdigital electrode 34 along the direction of sound wave propagation, and precisely matching the linewidth and spacing of the interdigital electrodes with the wavelength of the SAWs, ensures that the SAWs excited by the interdigital electrodes propagate directionally along the interdigital arrangement direction, avoiding energy loss and signal distortion caused by irregular scattering of sound waves, and guaranteeing the directionality and consistency of sound wave propagation. The cross-alternating arrangement of the first interdigital electrode 33 and the second interdigital electrode 34 between the first busbar 31 and the second busbar 32 forms multiple alternating electrode pairs, rather than a single pair. The simultaneous excitation of SAWs by multiple electrode pairs enables constructive interference of sound waves, superimposing and enhancing the sound wave amplitude, improving electroacoustic conversion efficiency, and reducing device insertion loss. The first busbar 31 provides a common electrical path for all first interdigital electrodes 33, and the second busbar 32 provides a common electrical path for all second interdigital electrodes 34. External radio frequency signals only need to be connected to the first busbar 31 and the second busbar 32 to synchronously load the signal onto all interdigital electrodes. Conversely, the electrical signal converted from surface acoustic wave can also be output centrally through the busbars, simplifying the electrical connections of the device while ensuring the synchronization of the electrical signals of all interdigital electrodes. Fixing one end of the first interdigital electrode 33 to the first busbar 31, which acts as a rigid support structure, improves the mechanical strength of the narrow interdigital electrodes and prevents electrode breakage due to stress during device packaging and use. At the same time, the large cross-sectional area design of the first busbar 31 reduces the contact resistance and wire resistance of the first interdigital electrode 33, reducing the transmission loss of electrical signals. Similarly, fixing one end of the second interdigital electrode 34 to the second busbar 32 produces the same effect. By ensuring that adjacent first interdigital electrodes 33 and second interdigital electrodes 34 do not contact each other, electrical isolation can be guaranteed, preventing device failure. The opposite polarities of adjacent first interdigital electrodes 33 and second interdigital electrodes 34 are used to form an alternating electric field, driving the piezoelectric substrate 2 to excite surface acoustic waves (SAWs). Simultaneously, this allows for the output of an alternating electrical signal when receiving SAWs. The period (interdigital period) of adjacent electrode pairs with opposite polarities is precisely matched with the wavelength of the SAWs, ensuring that the frequency of the excited SAWs matches the frequency of the externally applied radio frequency signal, avoiding signal distortion caused by frequency mismatch and guaranteeing the frequency selectivity of the device.

[0036] The sapphire is a r-faceted sapphire with a crystal arrangement in the shape of a regular hexagonal prism. The growth axis 4 of the r-faceted sapphire is perpendicular to its base surface, and the [2-1-1] crystal orientation 8 of the r-faceted sapphire is perpendicular to the orthogonal projection 7 of the growth axis 4 on the r-face 6 and parallel to the direction of acoustic wave propagation. By using r-faceted sapphire as a supporting substrate 1 and bonding it to a piezoelectric substrate 2, the unique crystal orientation of the r-faceted sapphire can reduce high-order clutter response and enable a surface acoustic wave device 100 with higher frequency, higher reliability, and higher power.

[0037] In this embodiment, the [2-1-1] crystal orientation 8 of the r-face sapphire is the crystal orientation index. Generally, it is determined by selecting a lattice point of the unit cell as the origin, using the three edges of the unit cell as coordinate axes, and the length of the edge as the unit length. If the desired crystal orientation does not pass through the origin, a directed straight line parallel to the desired crystal orientation is drawn through the origin. The coordinates u, v, and w of the lattice point closest to the origin on this directed straight line are calculated. The three coordinate values ​​are proportionally reduced to the smallest integers and placed sequentially in square brackets [], which are the desired crystal orientation indices. The coordinate values ​​u, v, and w are the projection components of the crystal orientation on the O-xyz three-dimensional rectangular coordinate axes, respectively. The coordinate values ​​u, v, and w are the projection components of the crystal orientation onto the three crystal axes of the unit cell. Essentially, they are dimensionless multiple ratios that reflect the orientation and extension of the crystal orientation onto the three crystal axes in three-dimensional space. The positive and negative signs indicate the projection direction, and the numerical values ​​indicate the multiple of the projection per unit length. Finally, after being simplified to the simplest integer, the crystal orientation index is obtained (e.g., [2-1-1]).

[0038] In this embodiment, the piezoelectric substrate 2 is made of at least one or more combined materials selected from quartz (SiO2), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT). Quartz exhibits the best temperature stability among all piezoelectric materials, resulting in filters with minimal temperature variation in center frequency, making it suitable for high-precision frequency selection. Lithium niobate utilizes its high piezoelectric coefficient to achieve efficient conversion between radio frequency signals and surface acoustic waves (SAW), while simultaneously providing a high-speed propagation path for SAW devices, making it the core piezoelectric substrate for wideband, low insertion loss SAW device filters. It also demonstrates good bonding compatibility with sapphire and silicon substrates, further suppressing acoustic energy leakage and improving the device's quality factor (Q value). Lithium tantalate has a moderate piezoelectric coefficient and good electro-acoustic conversion efficiency, balancing performance and stability. Aluminum nitride balances hypersonicity and high conversion efficiency. Zinc oxide has good adhesion and low cost. Lead zirconate titanate has extremely high capacitance, capable of withstanding high-power radio frequency signal input.

[0039] In this embodiment, the interdigital transducer 3 is made of one or more materials selected from copper (Cu), platinum (Pt), gold (Au), iron (Fe), aluminum (Al), nickel (Ni), titanium (Ti), chromium (Cr), molybdenum (Mo), and tantalum (Ta). This ensures strong compatibility between the interdigital transducer 3 and the bonding structure of the piezoelectric substrate 2 and the supporting substrate 1. The interdigital transducer 3 made of the aforementioned materials exhibits low loss, high reliability, and high-frequency / high-power adaptability.

[0040] In this embodiment, both the first interdigital electrode 33 and the second interdigital electrode 34 are multilayer structures formed of titanium, aluminum, and titanium. By using the high adhesion and high stability of titanium to compensate for the shortcomings of pure aluminum, and using the low resistivity of aluminum to ensure low RF loss, the three-layer structure forms a complementary performance. At the same time, it is adapted to the bonding process characteristics of the piezoelectric substrate 2 and the supporting substrate 1, achieving comprehensive performance of low loss, high adhesion, high process compatibility, and high reliability, which fully matches the mass production and application requirements of surface acoustic wave filters.

[0041] In this embodiment, the metallization ratios of both the first interdigital electrode 33 and the second interdigital electrode 34 are 0.4 to 0.8. Limiting the metallization ratio to the range of 0.4 to 0.8 is an optimal design for the core performance of the surface acoustic wave filter, including electro-acoustic conversion efficiency, frequency characteristics, bandwidth, insertion loss, and process feasibility. This avoids performance degradation caused by excessively high or low metallization ratios and matches the process characteristics of the heterogeneous structure of the titanium / aluminum / titanium (Ti / Al / Ti) three-layer electrode, the piezoelectric substrate 2, and the supporting substrate 1. Ultimately, this achieves a comprehensive effect of high-efficiency electro-acoustic conversion, wide bandwidth and low insertion loss, stable frequency response, and high process yield.

[0042] In this embodiment, the thickness of the first interdigital electrode 33 and the metallization ratio of the second interdigital electrode 34 are both 0.5. A metallization ratio of 0.5 is more effective.

[0043] In this embodiment, the thickness of both the first interdigital electrode 33 and the second interdigital electrode 34 is 7% to 10% of the period length (λ). The gap between the first interdigital electrode 33 and the second interdigital electrode 34 along the sound wave propagation direction is the gap width, and the total width of the electrode width of either the first interdigital electrode 33 or the second interdigital electrode 34 and the gap width is the period length. The thickness of the first interdigital electrode 33 is defined as a, the gap width as b, and the period length as λ; and the following conditions are satisfied:

[0044] λ = a + b.

[0045] The thickness and cycle length of the interdigitated electrodes can achieve a combination of low insertion loss, high quality factor, stable frequency response, and high process yield.

[0046] In this embodiment, the thickness of both the first interdigital electrode 33 and the second interdigital electrode 34 is 8% of the period length. This results in better performance of the surface acoustic wave device 100, including lower insertion loss, higher quality factor, stable frequency response, and higher process yield.

[0047] In this embodiment, the piezoelectric substrate 2 of the surface acoustic wave device 100 uses 42°YX-LiTaO3 (42°YX-cut lithium tantalate). The piezoelectric substrate 2 is bonded to the sapphire support substrate 1 through a bonding process, and an interdigital transducer 3 is fabricated on the surface of the piezoelectric substrate 2. For comparison, the c-plane sapphire is also bonded to the piezoelectric substrate 2 using the same bonding method. During bonding, the acoustic propagation direction of the piezoelectric substrate 2 is the x-axis, which is parallel to the

[110] crystal direction of the c-plane sapphire. When bonding with the r-plane sapphire, the x-axis of the piezoelectric substrate 2 is parallel to the [2-1-1] crystal direction 8 of the r-plane sapphire, that is, the bonding is performed parallel to the direction perpendicular to the projection of the c-axis.

[0048] In this embodiment, as Figure 3 This is a schematic diagram of the crystal structure of a conventional c-plane sapphire. Sapphire belongs to the hexagonal crystal system, with crystals arranged in a regular hexagonal prism shape. Typically, growth axis 4 is perpendicular to the bottom surface, and the surface of growth axis 4 in the diagram is the

[001] crystal direction. Crystal direction 5, perpendicular to growth axis 4, is the c-plane (001). This growth axis 4 (c-axis) refers to the direction with the fastest crystal growth rate and is also the

[0001] crystal direction in crystallography, serving as the core symmetry axis of the entire crystal structure. Growth axis 4 is a polar direction, and the c-plane (0001) grown along growth axis 4 is a polar plane. This introduces spontaneous polarization and piezoelectric polarization effects in heteroepitaxial materials such as GaN, directly affecting the luminous efficiency and voltage characteristics of optoelectronic devices. When it is necessary to grow a non-polar or semi-polar epitaxial layer, it is necessary to cut a non-polar crystal plane 6 off the c-axis to suppress the polarization effect.

[0049] In summary, as Figures 5-6 As shown, compared to the c-plane sapphire substrate, the surface acoustic wave (SAW) device 100 fabricated with the r-plane sapphire substrate exhibits a slight reduction in high-order clutter response around 2.5 GHz, while showing a significant reduction around 3.6 GHz. For the intermediate frequency (IF) B3 duplexer, its second harmonic is precisely around 3.6 GHz; therefore, using r-plane sapphire can significantly improve its harmonic characteristics. This demonstrates that the r-plane sapphire substrate holds greater potential for achieving higher frequency and higher power SAW devices 100. It can reduce high-order clutter response and achieve higher frequencies, higher reliability, and higher power.

[0050] It should be noted that the various embodiments described above with reference to the accompanying drawings are merely illustrative of the present invention and not intended to limit its scope. Those skilled in the art should understand that any modifications or equivalent substitutions made to the present invention without departing from its spirit and scope should be included within the scope of the present invention. Furthermore, unless the context otherwise requires, words appearing in the singular include those in the plural, and vice versa. Additionally, unless specifically stated otherwise, all or part of any embodiment may be used in conjunction with all or part of any other embodiment.

Claims

1. A surface acoustic wave device, characterized in that, The surface acoustic wave device includes a support substrate, a piezoelectric substrate stacked and fixed to the surface of the support substrate, and an interdigital transducer disposed on the side of the piezoelectric substrate away from the support substrate. The supporting substrate is made of sapphire material and is bonded to the piezoelectric substrate. The interdigital transducer includes a first interdigital electrode, a second interdigital electrode, and a first busbar and a second busbar spaced apart and opposite to each other. The first interdigital electrode and the second interdigital electrode are disposed between the first busbar and the second busbar. The first interdigital electrode and the second interdigital electrode are arranged in parallel and crosswise. The end of the first interdigital electrode near the first busbar is fixed to the first busbar, and the end of the second interdigital electrode near the second busbar is fixed to the second busbar. The first interdigital electrode is spaced apart from the second interdigital electrode and the second busbar, and the polarities of the first interdigital electrode and the second interdigital electrode are opposite. The first interdigital electrode and the second interdigital electrode are arranged in the direction of sound wave propagation. The sapphire is a r-faceted sapphire, the crystal arrangement of the r-faceted sapphire is a regular hexagonal prism, the growth axis of the r-faceted sapphire is perpendicular to its bottom surface, and the [2-1-1] crystal orientation of the r-faceted sapphire is perpendicular to the orthogonal projection of the growth axis on the r-face and parallel to the direction of sound wave propagation.

2. The surface acoustic wave device as described in claim 1, characterized in that, The piezoelectric substrate is made of at least one or more materials selected from quartz, lithium niobate, lithium tantalate, aluminum nitride, zinc oxide, and PZT.

3. The surface acoustic wave device as described in claim 1, characterized in that, The interdigital transducer is made of one or more materials selected from copper, platinum, gold, iron, aluminum, nickel, titanium, chromium, molybdenum, and tantalum.

4. The surface acoustic wave device as described in claim 3, characterized in that, Both the first interdigital electrode and the second interdigital electrode are multilayer structures formed of titanium, aluminum, and titanium.

5. The surface acoustic wave device as described in claim 1, characterized in that, The metallization ratios of both the first interdigital electrode and the second interdigital electrode are 0.4 to 0.

8.

6. The surface acoustic wave device as described in claim 5, characterized in that, The metallization ratio of both the first interdigital electrode and the second interdigital electrode is 0.

5.

7. The surface acoustic wave device as described in claim 1, characterized in that, The thickness of both the first interdigital electrode and the second interdigital electrode is 7% to 10% of the period length; Wherein, along the direction of sound wave propagation, the gap between adjacent first interdigital electrodes and second interdigital electrodes is the gap width, and the total width of the electrode width of the first interdigital electrode or the second interdigital electrode and the gap width is the period length; Defined as follows: the width of the first interdigital electrode is a, the gap width is b, and the period length is λ; and satisfying the following conditions: λ = a + b.

8. The surface acoustic wave device as described in claim 7, characterized in that, The thickness of both the first interdigital electrode and the second interdigital electrode is 8% of the period length.

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