Surface acoustic wave device

Abstract

The utility model provides a surface acoustic wave device. The surface acoustic wave device comprises a piezoelectric composite substrate and a metal structure located on the piezoelectric composite substrate. The piezoelectric composite substrate comprises a silicon substrate; the crystal elastic constant of the silicon substrate is a six-order matrix Cij, 0lt; i < = 6, 0lt; j < = 6, and i and j are integers; the silicon substrate has an Euler angle, and the absolute value of C15 in an elastic constant Cij defined by the Euler angle is greater than or equal to 2 * 10 < 9 > Pa. Namely, the Euler angle is set, and the absolute value of the elastic constant C15 of the silicon substrate is defined to be greater than or equal to 2 * 10 < 9 > Pa, so that the parasitic response generated by a high-order stray mode at high frequency is effectively eliminated or reduced, and the suppression capability of a stop band is improved. Compared with the prior art, the surface acoustic wave device provided by the utility model not only has a better inhibition effect on a high-frequency parasitic mode and improves the performance of the device, but also does not occupy the effective area of the device, is beneficial to the miniaturization development of the device, and is simple in process preparation.

Description

Surface Acoustic Wave Device Technical Field

[0001] The utility model relates to the technical field of semiconductor manufacturing, and particularly relates to a surface acoustic wave device. Background Technique

[0002] Surface acoustic wave (SAW) devices have the advantages of small size, low price, excellent performance, high mass production feasibility, etc., and are now widely used in the radio frequency front ends of modern communication system devices and portable communication devices.

[0003] At present, a surface acoustic wave device with high performance (Incredible High Performance Surface Acoustic Wave, I.H.P SAW) has good energy confinement in the thickness direction by adopting a laminated structure, but some higher-order spurious modes will be introduced additionally, resulting in the deterioration of the out-of-band suppression of the device. In this regard, the prior art generally adopts the following two methods to alleviate the parasitic response generated by the higher-order spurious modes. The first method is to suppress these high-frequency parasitic modes by adding an additional resonator. However, this method not only has a poor suppression effect, but also increases the size of the filter. The second method is to add a patterned structure at the interface of the laminated structure to scatter the higher-order clutter response. However, this method greatly increases the manufacturing difficulty of the process and has an adverse effect on the manufacturing of the top electrode.

[0004] Therefore, there is an urgent need for a new structure of surface acoustic wave device to solve the above technical problems. Summary of the Invention

[0005] The purpose of the utility model is to provide a surface acoustic wave device to solve the technical problem of how to suppress the high-frequency parasitic modes in the surface acoustic wave device.

[0006] To solve the above technical problems, the utility model provides a surface acoustic wave device, including: a piezoelectric composite substrate and a metal structure located on the piezoelectric composite substrate; wherein,

[0007] The piezoelectric composite substrate includes a silicon substrate; the elastic constant of the silicon substrate is a sixth-order matrix C ij , 0 < i ≤ 6, 0 < j ≤ 6, both i and j are integers; and the silicon substrate has Euler angles, and the elastic constant C ij defined by the Euler angles has an absolute value of C 15 greater than or equal to 2 × 10 9 Pa.

[0008] Optionally, in the surface acoustic wave device, the Euler angles of the silicon substrate include a first Euler angle, a second Euler angle, and a third Euler angle; the range of the first Euler angle is -30° to -60°, the range of the second Euler angle is -40° to -70°, and the range of the third Euler angle is -180° to 180°.

[0009] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is -45°, the second Euler angle is -54.74°, and the third Euler angle is -30°, -90°, -150°, 30°, 90°, or 150°, to define the elastic constant C. ij C 15 The absolute value is 1.37 × 10⁻⁶. 10 Pa.

[0010] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is -45°, the second Euler angle is -54.74°, and the third Euler angle is -15° or -45°, to define the elastic constant C. ij C 15 The absolute value is 9.67 × 10 9 Pa.

[0011] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is -45°, the second Euler angle is -40°, and the third Euler angle is -30°, to define the elastic constant C. ij C 15 The absolute value is 1.56 × 10⁻⁶. 10 Pa.

[0012] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is -45°, the second Euler angle is -70°, and the third Euler angle is -30°, to define the elastic constant C. ij C 15 The absolute value is 8.67 × 10 9 Pa.

[0013] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is -30°, the second Euler angle is -54.74°, and the third Euler angle is -30°, to define the elastic constant C. ij C 15 The absolute value is 5.53 × 10. 9 Pa.

[0014] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is -60°, the second Euler angle is -54.74°, and the third Euler angle is -30°, to define the elastic constant C. ij C15 The absolute value is 1.44 × 10⁻⁶. 10 Pa.

[0015] Optionally, in the surface acoustic wave device, the Euler angles of the silicon substrate include a first Euler angle, a second Euler angle, and a third Euler angle; the range of the first Euler angle is 120° to 150°, the range of the second Euler angle is 40° to 70°, and the range of the third Euler angle is -180° to 180°.

[0016] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is 135°, the second Euler angle is 54.74°, and the third Euler angle is -30°, -90°, -150°, 30°, 90°, or 150°, to define the elastic constant C. ij C 15 The absolute value is 1.37 × 10⁻⁶. 10 Pa.

[0017] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is 135°, the second Euler angle is 54.74°, and the third Euler angle is -15° or -45°, to define the elastic constant C. ij C 15 The absolute value is 9.67 × 10 9 Pa.

[0018] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is 135°, the second Euler angle is 40°, and the third Euler angle is -30°, to define the elastic constant C. ij C 15 The absolute value is 1.56 × 10⁻⁶. 10 Pa.

[0019] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is 135°, the second Euler angle is 70°, and the third Euler angle is -30°, to define the elastic constant C. ij C 15 The absolute value is 8.67 × 10 9 Pa.

[0020] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is 120°, the second Euler angle is 54.74°, and the third Euler angle is -30°, to define the elastic constant C. ij C 15 The absolute value is 8.67 × 10 9 Pa.

[0021] Optionally, in the surface acoustic wave device, the first Euler angle of the silicon substrate is 150°, the second Euler angle is 54.74°, and the third Euler angle is -30° to define the elastic constant C ij in C 15 The absolute value of is 5.53×10 9 Pa.

[0022] Optionally, in the surface acoustic wave device, the piezoelectric composite substrate further includes a first dielectric layer and a piezoelectric layer stacked on the silicon substrate in sequence.

[0023] Optionally, in the surface acoustic wave device, the piezoelectric composite substrate further includes a trap layer, and the trap layer is located between the silicon substrate and the first dielectric layer.

[0024] Optionally, in the surface acoustic wave device, the metal structure includes a plurality of interdigital electrodes, two bus bars, a plurality of dummy fingers, and a plurality of reflection gratings; wherein,

[0025] The plurality of interdigital electrodes and the plurality of dummy fingers are arranged at intervals in an alternating manner, the two bus bars are respectively connected to opposite ends of the plurality of interdigital electrodes, and the plurality of reflection gratings are located on the sides of the plurality of interdigital electrodes.

[0026] Optionally, in the surface acoustic wave device, a protective layer and / or a second dielectric layer are further provided on the surface of the metal structure.

[0027] Optionally, in the surface acoustic wave device, the surface acoustic wave device includes one or more of a resonator, a filter, and a duplexer.

[0028] In summary, the present invention provides a surface acoustic wave device. Among them, the surface acoustic wave device includes: a piezoelectric composite substrate and a metal structure located on the piezoelectric composite substrate; the piezoelectric composite substrate includes a silicon substrate; the crystal elastic constant of the silicon substrate is a sixth-order matrix C ij , 0 < i ≤ 6, 0 < j ≤ 6, both i and j are integers; and the silicon substrate has Euler angles, and the elastic constant C defined by the Euler angles ij in C 15 The absolute value of is greater than or equal to 2×10 9 Pa. That is, the present invention defines the elastic constant C of the silicon substrate by setting Euler angles 15 The absolute value of is greater than or equal to 2×10 9Furthermore, in combination with the surface acoustic wave (SAW) device structure, it effectively eliminates or reduces the parasitic response generated by high-frequency stray modes, thereby improving the stopband suppression capability. Compared with the prior art, the SAW device provided by this invention not only has a better suppression effect on high-frequency parasitic modes and improves device performance, but also does not require occupying the effective area of ​​the device, which is conducive to the miniaturization of the device, and the manufacturing process is simple. Attached Figure Description

[0029] Those skilled in the art will understand that the accompanying drawings are provided to better understand the present invention and do not constitute any limitation on the scope of the present invention. Wherein:

[0030] Figure 1 is a top view of the surface acoustic wave device in an embodiment of this utility model.

[0031] Figure 2 is a schematic cross-sectional view along A-A' of the surface acoustic wave device shown in Figure 1 in an embodiment of this utility model.

[0032] Figure 3 is a schematic diagram of the structure of a piezoelectric composite substrate in an embodiment of this utility model.

[0033] Figure 4 is a schematic diagram of another piezoelectric composite substrate in an embodiment of this utility model.

[0034] Figure 5 is a schematic diagram of the structure in which a protective layer is provided on the upper surface of the metal structure in an embodiment of this utility model.

[0035] Figure 6 is a schematic diagram of the structure in which a second dielectric layer is provided on the lower surface of the metal structure in an embodiment of the present invention.

[0036] Figure 7 is a schematic diagram of the structure of the metal structure in this embodiment, in which a protective layer and a second dielectric layer are provided on the upper and lower surfaces.

[0037] Figure 8 shows two different elastic constants C in the embodiments of this utility model. 15 Comparison of admittance curves for surface acoustic wave devices.

[0038] Figure 9 shows four different elastic constants C in the embodiments of this utility model. 15 Comparison of the real part admittance curves of the corresponding surface acoustic wave devices.

[0039] In the attached image:

[0040] 10-Piezoelectric composite substrate; 101-Silicon substrate; 102-First dielectric layer; 103-Piezoelectric layer; 104-Trap layer;

[0041] 20-Metal structure; 201-Interdigitated electrode; 202-Busbar; 203-Reflective grid;

[0042] 30 - Protective layer; 31 - Second dielectric layer. Detailed implementation

[0043] To make the purposes, advantages, and features of the present utility model clearer, the following further elaborates on the present utility model in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are all in a very simplified form and not drawn to scale, only for conveniently and clearly assisting in explaining the purposes of the embodiments of the present utility model. In addition, the structures shown in the accompanying drawings are often part of the actual structures. Specifically, the accompanying drawings need to show different focuses, and sometimes different scales are used. It should also be understood that unless otherwise specifically stated or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish each component, element, step, etc. in the specification, rather than to represent the logical relationship or sequential relationship, etc. between each component, element, step. And, in this specification, the X-axis, Y-axis, and Z-axis directions are respectively three mutually perpendicular directions in three-dimensional space.

[0044] Please refer to FIGS. 1 to 4. This embodiment provides a surface acoustic wave device, including: a piezoelectric composite substrate 10 and a metal structure 20 located on the piezoelectric composite substrate 10; wherein, the piezoelectric composite substrate 10 includes a silicon substrate 101; the crystal elastic constant of the silicon substrate 101 is a sixth-order matrix C ij , 0 < i ≤ 6, 0 < j ≤ 6, both i and j are integers; and the silicon substrate 101 has Euler angles, and the elastic constant C ij in C 15 has an absolute value greater than or equal to 2×10 9 Pa.

[0045] Based on this, the surface acoustic wave device provided in this embodiment realizes a better suppression effect on high-frequency parasitic modes and improves the device performance by setting Euler angles to define that the absolute value of C ij in the sixth-order matrix C 15 is greater than or equal to 2×10 9 Pa.

[0046] The following specifically describes the surface acoustic wave device provided in this embodiment with reference to FIGS. 1 to 9.

[0047] It should be noted that the surface acoustic wave (SAW) device provided in this embodiment can be a resonator, a filter, or a duplexer, or a radio frequency module including at least one of a resonator, a filter, and a duplexer. Regardless of the specific structure of the SAW device, it includes a piezoelectric composite substrate 10 and a metal structure 20 located on the piezoelectric composite substrate 10. The piezoelectric composite substrate 10 generates SAW waves using the inverse piezoelectric effect of its own piezoelectric material, while the metal structure 20 is used for acoustic-to-electric conversion, reflection filtering, and connection to external circuits.

[0048] In one example, as shown in FIG3, the piezoelectric composite substrate 10 includes a silicon substrate 101, a first dielectric layer 102, and a piezoelectric layer 103 stacked sequentially. In another example, as shown in FIG4, the piezoelectric composite substrate 10 includes a silicon substrate 101, a trap layer 104, a first dielectric layer 102, and a piezoelectric layer 103 stacked sequentially. Optionally, the silicon substrate 101 is made of silicon; the first dielectric layer 102 is made of, but is not limited to, silicon oxide, tetraethyl orthosilicate (TEOS), and silicon nitride; the piezoelectric layer 103 is made of, but is not limited to, lithium tantalate, lithium niobate, aluminum nitride, zinc oxide, and lead zirconate titanate (PZT); and the trap layer 104 is made of, but is not limited to, polycrystalline silicon, amorphous silicon, aluminum nitride, aluminum oxide, silicon carbide, and gallium nitride.

[0049] Please refer to Figures 1 and 2. The metal structure 20 includes multiple interdigitated electrodes 201, two busbars 202, several pseudo-finger electrodes (not shown), and several reflective gates 203. Specifically, the multiple interdigitated electrodes 201 and the several pseudo-finger electrodes are arranged alternately, with an arrangement resembling a comb. The two busbars 202 connect the opposite ends of the multiple interdigitated electrodes 201. The several reflective gates 203 are located on the sides of the multiple interdigitated electrodes 201; for example, one reflective gate 203 is disposed on each side of the interdigitated electrode 201. The interaction between the interdigitated electrodes 201 and the piezoelectric composite substrate 10 enables the mutual conversion of electrical signals and acoustic signals. The busbar 202 is used to converge the current on each of the interdigital electrodes 201, or to distribute the externally input current to each of the interdigital electrodes 201, thereby achieving effective transmission and distribution of electrical signals in the interdigital electrodes 201, ensuring that the interdigital electrodes 201 can work normally and realize electroacoustic conversion. The pseudo-finger electrodes are mainly used to suppress parasitic modes such as transverse high-order modes, reduce the impact of these modes on device performance, and improve the stability and filtering characteristics of the device. Furthermore, the reflector grating 203 reflects sound waves, allowing them to propagate back and forth between the interdigital electrodes 201 and form resonance; and by adjusting the structure and position of the reflector grating 203, precise control of the sound wave propagation path and reflection characteristics can be achieved, thereby optimizing device performance.

[0050] Optionally, the material of the metal structure 20 may include, but is not limited to, gold, silver, aluminum, copper, tungsten, or other metal alloys. Furthermore, the metal structure 20 may be a single layer of metal or a combination of multiple layers of different metals stacked together.

[0051] Based on this, in one example, as shown in Figure 2, the metal structure 20 is directly disposed on the top surface of the piezoelectric composite substrate 10. In other examples, a protective layer 30 and / or a second dielectric layer 31 are also disposed on the surface of the metal structure 20 to provide isolation and protection and optimize electrical performance. The surface of the metal structure 20 includes opposing upper and / or lower surfaces. For example, as shown in Figure 5, a protective layer 30 covers the upper surface of the metal layer 20. As shown in Figure 6, a second dielectric layer 31 is also disposed on the lower surface of the metal layer 20; that is, between the metal layer 20 and the piezoelectric composite substrate 10. As shown in Figure 7, a protective layer 30 and a second dielectric layer 31 are respectively disposed on the upper and lower surfaces of the metal layer 20. Optionally, the materials of the protective layer 30 and the second dielectric layer 31 include, but are not limited to, silicon oxide, TEOS, or silicon nitride.

[0052] Furthermore, since some high-order spurious modes are introduced in the existing surface acoustic wave devices, resulting in the deterioration of the out-of-band suppression of the devices, the surface acoustic wave device provided in this embodiment restricts the elastic constant C of the silicon substrate 101 by defining the Euler angles of the silicon substrate 101 15 , thereby effectively reducing or eliminating the parasitic responses generated by the high-order spurious modes at high frequencies and improving the suppression ability of the stopband.

[0053] It should be noted that the Euler angles are used to characterize the crystal orientation. Therefore, the crystal orientation of the silicon substrate 101 is defined by the first Euler angle α, the second Euler angle θ, and the third Euler angle . The Euler angles (α, θ, ) can accurately describe any orientation of the crystal in three-dimensional space. Among them, crystals with different crystal orientations have different elastic constants, that is, crystals with different Euler angles have different elastic constants. And based on the definitions of the first Euler angle α, the second Euler angle θ, and the third Euler angle , the elastic constants of the crystal can be determined. The elastic constant is a physical quantity that describes the relationship between stress and strain within the elastic range of the crystal. And in the coordinate system defined by the Euler angles, these elastic constants are used to quantify the elastic properties of the crystal under a specific orientation.

[0054] Based on this, the three-dimensional crystal elastic constants of the silicon substrate 101 can be expressed by the following formula 1. Among them, the crystal elastic constant of the silicon substrate 101 is a sixth-order matrix C ij , 0 < i ≤ 6, 0 < j ≤ 6, both i and j are integers; and C ij is obtained by performing rotational processing of the elastic constant tensor C0 of silicon through three Euler angles respectively.

[0055] Formula 1:

[0056]

[0057] Furthermore, the elastic constant C ij = M * C0 * M T , and the calculation of M is shown in the following formulas (2) to (6):

[0058] Formula 2:

[0059]

[0060] Formula 3:

[0061]

[0062] Formula 4:

[0063]

[0064] Formula 5:

[0065]

[0066] Formula 6:

[0067]

[0068] Therefore, by defining the Euler angles and combining them with the above formula, the elastic constants of the crystal can be accurately calculated. Optionally, the silicon substrate 101 provided in this embodiment has Euler angles so that the sixth-order matrix C ij C 15 The absolute value is greater than or equal to 2 × 10 9 Pa, in combination with the structure of the surface acoustic wave device provided in this embodiment, can reduce or eliminate the parasitic response generated by high-order stray modes located at high frequencies, thereby improving the stopband suppression capability.

[0069] Optionally, the first Euler angle of the silicon substrate 101 ranges from -30° to -60°, the second Euler angle ranges from -40° to -70°, and the third Euler angle ranges from -180° to 180°.

[0070] For example, based on the surface acoustic wave device provided in this embodiment, the material of the piezoelectric layer 103 is lithium tantalate; and the angle between the cut surface of the lithium tantalate along the Y-axis and the crystal reference plane of the lithium tantalate is 42° (denoted as 42°Y-cut); the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The value is any one of -30°, -90°, -150°, 30°, 90°, or 150°. The elastic constant C is defined based on the Euler angles specified above. ij C 15 The absolute value is 1.37 × 10⁻⁶. 10 Pa.

[0071] Specifically, when the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The elastic constant C is defined at -30°. ij As shown in Formula 7:

[0072] Formula 7:

[0073]

[0074] When the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The elastic constant C is defined at -90°. ij As shown in Formula 8:

[0075] Formula 8:

[0076]

[0077] When the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The elastic constant C is defined at -150°. ij As shown in Formula 9:

[0078] Formula 9:

[0079]

[0080] When the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The elastic constant C is defined at 30°. ij As shown in Formula 10:

[0081] Formula 10:

[0082]

[0083] When the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The elastic constant C is defined when the angle is 90°. ij As shown in Formula 11:

[0084] Formula 11:

[0085]

[0086] When the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The elastic constant C is defined at 150°. ij As shown in Formula 12:

[0087] Formula 12:

[0088]

[0089] And, when the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The value is -15° or -45°, to define the elastic constant C. ij C 15 The absolute value is 9.67 × 10 9 Pa. That is, when the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The elastic constant C is defined at -15°. ij As shown in Formula 13:

[0090] Formula 13:

[0091]

[0092] When the first Euler angle α of the silicon substrate 101 is -45°, the second Euler angle θ is -54.74°, and the third Euler angle... The elastic constant C is defined at -45°. ij As shown in Formula 14:

[0093] Formula 14:

[0094]

[0095] When the first Euler angle of the silicon substrate 101 is -45°, the second Euler angle is -40°, and the third Euler angle is -30°, the elastic constant C is defined. ij C 15 The absolute value is 1.56 × 10⁻⁶. 10 Pa, and specifically the elastic constant C ij As shown in Formula 15:

[0096] Formula 15:

[0097]

[0098] When the first Euler angle of the silicon substrate 101 is -45°, the second Euler angle is -70°, and the third Euler angle is -30°, the elastic constant C is defined. ij C 15 The absolute value is 8.67 × 10 9 Pa, and specifically the elastic constant C ij As shown in Formula 16:

[0099] Formula 16:

[0100]

[0101] When the first Euler angle of the silicon substrate 101 is -30°, the second Euler angle is -54.74°, and the third Euler angle is -30°, the elastic constant C is defined. ij C 15 The absolute value is 5.53 × 10. 9 Pa, and specifically the elastic constant C ij As shown in Formula 17:

[0102] Formula 17:

[0103]

[0104] When the first Euler angle of the silicon substrate 101 is -60°, the second Euler angle is -54.74°, and the third Euler angle is -30°, the elastic constant C is defined. ij C 15 The absolute value is 1.44 × 10⁻⁶. 10 Pa, and specifically the elastic constant C ij As shown in Formula 18:

[0105] Formula 18:

[0106]

[0107] Optionally, the first Euler angle of the silicon substrate 101 ranges from 120° to 150°, the second Euler angle ranges from 40° to 70°, and the third Euler angle ranges from -180° to 180°.

[0108] For example, based on the surface acoustic wave device provided in this embodiment, the material of the piezoelectric layer 103 is lithium tantalate; and the angle between the cut surface of the lithium tantalate along the Y-axis and the crystal reference plane of the lithium tantalate is 42° (denoted as 42°Y-cut); the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The value is any one of -30°, -90°, -150°, 30°, 90°, or 150°. The elastic constant C is defined based on the Euler angles specified above. ij C 15 The absolute value is 1.37 × 10⁻⁶. 10 Pa.

[0109] Specifically, when the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The elastic constant C is defined at -30°. ij As shown in Formula 19:

[0110] Formula 19:

[0111]

[0112] When the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The elastic constant C is defined at -90°. ij As shown in Formula 20:

[0113] Formula 20:

[0114]

[0115] When the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The elastic constant C is defined at -150°. ij As shown in Formula 21:

[0116] Formula 21:

[0117]

[0118] When the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The elastic constant C is defined at 30°. ij As shown in Formula 22:

[0119] Formula 22:

[0120]

[0121] When the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The elastic constant C is defined when the angle is 90°. ij As shown in Formula 23:

[0122] Formula 23:

[0123]

[0124] When the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The elastic constant C is defined at 150°. ij As shown in Formula 24:

[0125] Formula 24:

[0126]

[0127] When the first Euler angle of the silicon substrate 101 is 135°, the second Euler angle is 54.74°, and the third Euler angle is -15° or -45°, the elastic constant C is defined. ij C 15 The absolute value is 9.67 × 10 9 Pa. That is, when the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The elastic constant C is defined at -15°. ij As shown in Formula 25:

[0128] Formula 25:

[0129]

[0130] When the first Euler angle α of the silicon substrate 101 is 135°, the second Euler angle θ is 54.74°, and the third Euler angle... The elastic constant C is defined at -45°. ij As shown in Formula 26:

[0131] Formula 26:

[0132]

[0133] When the first Euler angle of the silicon substrate 101 is 135°, the second Euler angle is 40°, and the third Euler angle is -30°, the elastic constant C is defined. ij C 15 The absolute value is 1.56 × 10⁻⁶. 10 Pa, and specifically the elastic constant C ij As shown in Formula 27:

[0134] Formula 27:

[0135]

[0136] When the first Euler angle of the silicon substrate 101 is 135°, the second Euler angle is 70°, and the third Euler angle is -30°, the elastic constant C is defined. ij C 15 The absolute value is 8.67 × 10 9 Pa, and specifically the elastic constant C ij As shown in Formula 28:

[0137] Formula 28:

[0138]

[0139] When the first Euler angle of the silicon substrate 101 is 120°, the second Euler angle is 54.74°, and the third Euler angle is -30°, the elastic constant C is defined. ij C 15 The absolute value is 8.67 × 10 9 Pa, and specifically the elastic constant C ij As shown in Formula 29:

[0140] Formula 29:

[0141]

[0142] When the first Euler angle of the silicon substrate 101 is 150°, the second Euler angle is 54.74°, and the third Euler angle is -30°, the elastic constant C is defined. ij C 15 The absolute value is 5.53 × 10. 9 Pa, and specifically the elastic constant C ij As shown in Formula 30:

[0143] Formula 30:

[0144]

[0145] Furthermore, please refer to Figure 8. The solid line in Figure 8 represents the surface acoustic wave device provided in this embodiment, that is, the elastic constant C defined by the Euler angle of the silicon substrate 101. 15 The absolute value is greater than or equal to 2 × 10 9Pa. The conductivity curve shown by the dashed line corresponds to the surface acoustic wave (SAW) device in the prior art, which uses common silicon material as the substrate. A comparison clearly shows that the dominant mode characteristics of the SAW device provided in this embodiment remain unchanged, and the amplitude of higher-order modes is significantly reduced, effectively suppressing the parasitic response generated by high-frequency stray modes, thus improving the stopband suppression capability. Furthermore, compared to the prior art, by setting the Euler angle of the silicon substrate 101, the elastic constant C is limited. 15 The absolute value is greater than or equal to 2 × 10 9 The manufacturing difficulty of Pa is significantly lower than that of adding patterned structures at the interface of the stacked structure, and it does not require additional resonators to suppress high-frequency parasitic modes by occupying device size.

[0146] Therefore, the surface acoustic wave device provided in this embodiment can not only effectively suppress parasitic responses generated by high-order stray modes at high frequencies and improve the suppression capability of the stopband, but also has a simple process and does not require occupying the effective area of ​​the device.

[0147] To fully verify the setting of Euler angles, so that the elastic constant C of the silicon substrate 101 is... 15 The absolute value is greater than or equal to 2 × 10 9 To assess the effectiveness of eliminating parasitic responses generated by high-frequency, high-order stray modes at Pa, the applicant conducted the following tests and data comparisons:

[0148] First, the surface acoustic wave device described in this embodiment is provided, wherein the piezoelectric layer 103 is made of 42° Y-cut lithium tantalate, and the crystal orientation of the silicon substrate 101 has a first Euler angle of 135°, a second Euler angle of 54.74°, and a third Euler angle of -30°, and the elastic constant C shown in Formula 19 is obtained. ij And C 15 The absolute value is 1.37 × 10⁻⁶. 10 Pa. In addition, the applicant has also provided three sets of surface acoustic wave (SAW) devices for comparison. In the first set of comparative SAW devices, the piezoelectric layer 103 is made of 42° Y-cut lithium tantalate, and the silicon substrate 101 has a crystal orientation with a first Euler angle of 90°, a second Euler angle of 90°, and a third Euler angle of 45°; and the elastic constant C... 15 The absolute value is 2.96 × 10. -21 Pa, from which we can obtain the following formula 31.

[0149] Formula 31:

[0150]

[0151] In the second set of comparative surface acoustic wave devices, the piezoelectric layer 103 is made of 42° Y-cut lithium tantalate, and the crystal orientation of the silicon substrate 101 has a first Euler angle of 135°, a second Euler angle of 90°, and a third Euler angle of 75°; and the elastic constant C... 15 The absolute value is 7.33 × 10. -6 Pa, from which we can obtain the following formula 32.

[0152] Formula 32:

[0153]

[0154] In the third set of comparative surface acoustic wave devices, the piezoelectric layer 103 is made of 42° Y-cut lithium tantalate; the silicon substrate 101 has a crystal orientation with a first Euler angle of 120°, a second Euler angle of 90°, and a third Euler angle of 60°; and the elastic constant C... 15 The absolute value is 1.57 × 10⁻⁶. 9 Pa, from which we can obtain the following formula 33.

[0155] Formula 33:

[0156]

[0157] Based on this, according to the comparison diagram of the real part of the admittance curve shown in Figure 9 and the elastic constant C under the preset Euler angle shown in Table 1 below, 15 The data table comparing the displacement shows that when the elastic constant C 15 A larger value indicates a smaller displacement of the higher-order modes excited by the surface acoustic wave device, which means a lower excitation efficiency of the higher-order modes and a lower corresponding admittance amplitude. This fully verifies the validity of setting C in this embodiment. 15 The absolute value is greater than or equal to 2 × 10 9 When Pa, it can effectively suppress or eliminate parasitic responses generated by high-frequency high-order stray modes.

[0158] Table 1 Multiple sets of elastic constants C 15 Comparison of displacement data table

[0159] SAW Group 1, SAW Group 2, SAW Group 3, SAW provided in this implementation. 15 (Pa) 2.96×10 -21 7.33×10 -6 1.57×10 9 1.37×10 10 Displacement (m) 9.5 × 10 -11 2.8×10 -11 1.63×10 -11 1.2×10-11 surface

[0160] In summary, the surface acoustic wave device provided in this embodiment defines the elastic constant C by limiting the Euler angles of the silicon substrate 101. 15 The absolute value is greater than or equal to 2 × 10 9 Furthermore, in combination with the surface acoustic wave (SAW) device structure, it effectively eliminates or reduces parasitic responses generated by high-frequency stray modes, thereby improving the stopband suppression capability. Compared with the prior art, the SAW device provided in this embodiment not only has a better suppression effect on high-frequency parasitic modes and improves device performance, but also does not require occupying the effective area of ​​the device, which is conducive to the miniaturization of the device, and the fabrication process is simple.

[0161] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the present invention's technical solutions using the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention's technical solutions. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention's technical solutions, shall still fall within the protection scope of the present invention's technical solutions.

Claims

1. A surface acoustic wave device, characterized in that, include: A piezoelectric composite substrate and a metal structure located on the piezoelectric composite substrate; wherein, the piezoelectric composite substrate includes a silicon substrate; the elastic constant of the silicon substrate is a sixth-order matrix C ij , 0 < i ≤ 6, 0 < j ≤ 6, both i and j are integers; and the silicon substrate has Euler angles, and the elastic constant C defined by the Euler angles ij in C 15 has an absolute value greater than or equal to 2 × 10 9 Pa.

2. The surface acoustic wave device according to claim 1, characterized in that, The Euler angles of the silicon substrate include a first Euler angle, a second Euler angle, and a third Euler angle; the range of the first Euler angle is -30° to -60°, the range of the second Euler angle is -40° to -70°, and the range of the third Euler angle is -180° to 180°.

3. The surface acoustic wave device according to claim 1 or 2, characterized in that, The first Euler angle of the silicon substrate is -45°, the second Euler angle is -54.74°, and the third Euler angle is -30°, -90°, -150°, 30°, 90°, or 150°, to define the elastic constant C. ij C 15 The absolute value is 1.37 × 10⁻⁶. 10 Pa.

4. The surface acoustic wave device according to claim 1 or 2, characterized in that, The first Euler angle of the silicon substrate is -45°, the second Euler angle is -54.74°, and the third Euler angle is -15° or -45°, to define the elastic constant C. ij C 15 The absolute value is 9.67 × 10 9 Pa.

5. The surface acoustic wave device according to claim 1 or 2, characterized in that, The silicon substrate has a first Euler angle of -45°, a second Euler angle of -40°, and a third Euler angle of -30°, to define the elastic constant C. ij C 15 The absolute value is 1.56 × 10⁻⁶. 10 Pa.

6. The surface acoustic wave device according to claim 1 or 2, characterized in that, The silicon substrate has a first Euler angle of -45°, a second Euler angle of -70°, and a third Euler angle of -30°, to define the elastic constant C. ij C 15 The absolute value is 8.67 × 10 9 Pa.

7. The surface acoustic wave device according to claim 1 or 2, characterized in that, The silicon substrate has a first Euler angle of -30°, a second Euler angle of -54.74°, and a third Euler angle of -30°, to define the elastic constant C. ij C 15 The absolute value is 5.53 × 10. 9 Pa.

8. The surface acoustic wave device according to claim 1 or 2, characterized in that, The silicon substrate has a first Euler angle of -60°, a second Euler angle of -54.74°, and a third Euler angle of -30°, to define the elastic constant C. ij C 15 The absolute value is 1.44 × 10⁻⁶. 10 Pa.

9. The surface acoustic wave device according to claim 1, characterized in that, The Euler angles of the silicon substrate include a first Euler angle, a second Euler angle, and a third Euler angle; the range of the first Euler angle is 120° to 150°, the range of the second Euler angle is 40° to 70°, and the range of the third Euler angle is -180° to 180°.

10. The surface acoustic wave device according to claim 1 or 9, characterized in that, The first Euler angle of the silicon substrate is 135°, the second Euler angle is 54.74°, and the third Euler angle is -30°, -90°, -150°, 30°, 90°, or 150°, to define the elastic constant C. ij C 15 The absolute value is 1.37 × 10⁻⁶. 10 Pa.

11. The surface acoustic wave device according to claim 1 or 9, characterized in that, The silicon substrate has a first Euler angle of 135°, a second Euler angle of 54.74°, and a third Euler angle of -15° or -45°, to define the elastic constant C. ij C 15 The absolute value is 9.67 × 10 9 Pa.

12. The surface acoustic wave device according to claim 1 or 9, characterized in that, The silicon substrate has a first Euler angle of 135°, a second Euler angle of 40°, and a third Euler angle of -30°, to define the elastic constant C. ij C 15 The absolute value is 1.56 × 10⁻⁶. 10 Pa.

13. The surface acoustic wave device according to claim 1 or 9, characterized in that, The silicon substrate has a first Euler angle of 135°, a second Euler angle of 70°, and a third Euler angle of -30°, to define the elastic constant C. ij C 15 The absolute value is 8.67 × 10 9 Pa.

14. The surface acoustic wave device according to claim 1 or 9, characterized in that, The silicon substrate has a first Euler angle of 120°, a second Euler angle of 54.74°, and a third Euler angle of -30°, to define the elastic constant C. ij C 15 The absolute value is 8.67 × 10 9 Pa.

15. The surface acoustic wave device according to claim 1 or 9, characterized in that, The silicon substrate has a first Euler angle of 150°, a second Euler angle of 54.74°, and a third Euler angle of -30°, to define the elastic constant C. ij C 15 The absolute value is 5.53 × 10. 9 Pa.

16. The surface acoustic wave device according to claim 1, characterized in that, The piezoelectric composite substrate further includes a first dielectric layer and a piezoelectric layer sequentially stacked on the silicon substrate.

17. The surface acoustic wave device according to claim 16, characterized in that, The piezoelectric composite substrate further includes a trap layer, and the trap layer is located between the silicon substrate and the first dielectric layer.

18. The surface acoustic wave device according to claim 1, characterized in that, The metal structure includes multiple interdigitated electrodes, two busbars, several pseudo-finger electrodes, and several reflective grids; wherein the multiple interdigitated electrodes and the several pseudo-finger electrodes are arranged alternately, the two busbars are respectively connected to the opposite ends of the multiple interdigitated electrodes, and the several reflective grids are located on the sides of the multiple interdigitated electrodes.

19. The surface acoustic wave device according to claim 1 or 18, characterized in that, A protective layer and / or a second dielectric layer are also provided on the surface of the metal structure.

20. The surface acoustic wave device according to claim 1, characterized in that, The surface acoustic wave device includes one or more of the following: resonator, filter, and duplexer.

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