An elastic wave resonator, filter, multiplexer and radio frequency front-end circuit

Abstract

The invention discloses an elastic wave resonator, a filter, a multiplexer and a radio frequency front-end circuit. The elastic wave resonator comprises a sapphire substrate, a functional film layer, a lithium tantalate piezoelectric layer and an interdigital transducer which are stacked in sequence; the polarity of the frequency temperature coefficient of the piezoelectric layer and the functional film layer is opposite; when the sapphire substrate adopts different Euler angles, the product of the ratio of the normalized thickness of the piezoelectric layer to the normalized thickness of the functional film layer and the third angle in the Euler angle meets different ranges. By setting the substrate to adopt a sapphire substrate, and setting the sapphire substrate to adopt different Euler angles, the product of the ratio of the normalized thickness of the piezoelectric layer to the normalized thickness of the functional film layer and the third angle in the Euler angle meets different ranges, the performance of the elastic wave resonator can be improved, the response of the high-order parasitic body wave of the elastic wave resonator on the high-frequency side can be weakened or suppressed, the wave velocity and electromechanical coupling coefficient of the elastic wave resonator can be improved, the manufacturing process can be simplified, and the cost can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of resonators, and in particular to an elastic wave resonator, a filter, a multiplexer and a radio frequency front-end circuit. Background Art

[0002] In the prior art, a variety of elastic wave devices using single crystal silicon as a substrate have been proposed. For example, an elastic wave resonator is formed by sequentially providing an insulating layer and a piezoelectric layer on a single crystal silicon substrate. However, the above elastic wave resonator has the following problems:

[0003] First, the electromagnetic field generated by the propagation of high-frequency signals in the elastic wave resonator in the device will penetrate into the interior of the laminated structure composed of the insulating layer and the piezoelectric layer, and interact with the charge carriers in the entire field, resulting in nonlinear distortion of the signal (harmonics / intermodulation), acoustic wave energy loss, crosstalk between adjacent devices, and deterioration of the device quality factor. In response to the above problems, the existing known solution is to set a polycrystalline silicon capture layer between the single crystal silicon substrate and the insulating film layer, and use the polycrystalline silicon capture layer to absorb the charge carriers in the field that interfere with the performance of the device, thereby improving the performance level of the elastic wave resonator. However, the manufacturing process of the polycrystalline silicon capture layer is complicated and costly, and it usually undergoes a partial recrystallization process during the manufacturing process, which will cause the density of the traps that play a capture role to decrease and make its function of absorbing charge carriers ineffective.

[0004] Secondly, the elastic wave resonator using a laminated structure composed of an insulating layer and a piezoelectric layer has high-order body wave parasitic modes on the high-frequency side of the main mode operating frequency (resonant frequency and anti-resonant frequency), which will affect the attenuation and harmonic performance of the elastic wave filter including the elastic wave resonator outside the passband. In view of the above problems, the existing known solution is to arrange regular convex parts and / or concave parts on the substrate or the insulating layer to achieve high-order parasitic mode suppression. However, the above manufacturing process is complicated, and the convex and concave structures are not easy to control. Summary of the invention

[0005] The present invention provides an elastic wave resonator, a filter, a multiplexer and a radio frequency front-end circuit, so as to provide an elastic wave resonator with simple manufacturing process, low cost and capable of improving the performance of the elastic resonator.

[0006] In a first aspect, an embodiment of the present invention provides an elastic wave resonator, which includes: a substrate, including a sapphire substrate; a functional film layer, arranged on one side of the substrate; a piezoelectric layer, including a lithium tantalate piezoelectric layer, and the piezoelectric layer is arranged on a side of the functional film layer away from the substrate; the frequency temperature coefficient of the functional film layer is opposite to the polarity of the frequency temperature coefficient of the piezoelectric layer; an interdigital transducer, arranged on a side of the piezoelectric layer away from the functional film layer; when the Euler angle of the substrate is (90°, 90°, γ°), it satisfies: 7.5≤(H2 / H1)×γ≤300 or 30≤(H2 / H1)×γ≤480; when the Euler angle of the substrate is (0°, 0°, γ°), it satisfies: 0≤(H2 / H1)× γ≤120 or 22.5≤(H2 / H1)×γ≤600; when the Euler angle of the substrate is (0°, 90°, γ°), it satisfies: 10≤(H2 / H1)×γ≤240 or 30≤(H2 / H1)×γ≤510; when the Euler angle of the substrate is (0°, 122.23°, γ°), it satisfies: 5≤(H2 / H1)×γ≤300 or 25≤(H2 / H1)×γ≤540; wherein, H1=h1 / λ; H2=h2 / λ; λ represents the wavelength of the elastic wave in the elastic wave resonator; H1 represents the normalized thickness of the functional film layer, and h1 represents the actual thickness of the functional film layer; H2 represents the normalized thickness of the piezoelectric layer, and h2 represents the actual thickness of the piezoelectric layer.

[0007] Optionally, the actual thickness h1 of the functional film layer satisfies 0.05λ≤h1≤1.2λ; and the actual thickness h2 of the piezoelectric layer satisfies 0.05λ≤h2≤5λ.

[0008] Optionally, the frequency temperature coefficient TCV1 of the functional film layer satisfies +20ppm / °C≤TCV1≤+72ppm / °C.

[0009] Optionally, the functional film layer includes a silicon oxide layer and / or a silicon oxynitride layer.

[0010] Optionally, the Euler angle of the substrate is (0°, 0°, 0°) or (0°, 0°, 30°) or (0°, 0°, 90°); or, the Euler angle of the substrate is (90°, 90°, 60°) or (90°, 90°, 140°); or, the Euler angle of the substrate is (0°, 90°, 60°) or (0°, 90°, 150°) or (0°, 90°, 155°); or, the Euler angle of the substrate is (0°, 122.23°, 30°) or (0°, 122.23°, 60°) or (0°, 122.23°, 160°).

[0011] Optionally, the elastic wave resonator further includes a capture layer, and the capture layer is arranged between the substrate and the functional film layer; the material of the capture layer includes polycrystalline silicon, amorphous silicon, mesoporous silicon, silicon nitride or glass.

[0012] Optionally, the elastic wave resonator further includes a capture layer, wherein the capture layer is disposed between the substrate and the functional film layer; and an actual thickness h3 of the capture layer satisfies 0.05λ≤h3≤0.5λ.

[0013] In a second aspect, an embodiment of the present invention provides an elastic wave filter, which includes the elastic wave resonator as described in the first aspect.

[0014] In the third aspect, an embodiment of the present invention provides an elastic wave multiplexer, which includes an antenna, at least one receiving unit and at least one transmitting unit; the antenna is communicatively connected to the receiving unit and the transmitting unit respectively; at least one of the receiving unit and the transmitting unit includes the elastic wave filter as described in the second aspect.

[0015] In a fourth aspect, an embodiment of the present invention provides a radio frequency front-end circuit, which includes the elastic wave multiplexer as described in the third aspect.

[0016] The technical solution of the embodiment of the present invention can solve the problems of signal nonlinear distortion (harmonics / intermodulation), acoustic wave energy loss, crosstalk between adjacent devices, device quality factor deterioration, etc. that exist in the resonator due to the use of a single crystal silicon substrate by setting the substrate to be an insulating sapphire substrate. There is no need to set a capture layer to absorb charge carriers that interfere with device performance in the field, which can simplify the manufacturing process and reduce costs. Moreover, by setting the substrate to be a sapphire substrate, the response of high-order parasitic body waves of the elastic wave resonator on the high-frequency side can be weakened or suppressed. There is no need to arrange regular protrusions and / or recesses on the substrate or the insulating layer to achieve high-order parasitic mode suppression, which can further simplify the manufacturing process and reduce costs. By setting the substrate to be a sapphire substrate, the elastic wave resonator can also have a higher wave speed and electromechanical coupling coefficient, which is conducive to the miniaturization and larger bandwidth of high-frequency devices.

[0017] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A cross-sectional schematic diagram of an elastic wave resonator provided in an embodiment of the present invention.

[0020] Figure 2 A schematic structural diagram of an interdigital transducer provided in an embodiment of the present invention.

[0021] Figure 3 A schematic diagram of the crystal structure of a sapphire crystal used for a substrate provided in an embodiment of the present invention.

[0022] Figure 4 The present invention provides an admittance characteristic curve of an elastic wave resonator provided by the prior art.

[0023] Figure 5 A schematic diagram of the relationship between the wave velocity of the first high-order body wave and the wave velocity of the second high-order body wave and the value of (H2 / H1)×γ in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (90°, 90°, γ).

[0024] Figure 6 A schematic diagram of the change between the normalized frequency difference between the first high-order bulk wave and the second high-order bulk wave and the (H2 / H1)×γ value in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (90°, 90°, γ).

[0025] Figure 7 A schematic diagram of the relationship between the main mode admittance ratio of an elastic wave resonator and the (H2 / H1)×γ value when the Euler angle of the substrate provided in an embodiment of the present invention is (90°, 90°, γ).

[0026] Figure 8 A schematic diagram of the relationship between the wave velocity of the first high-order body wave and the wave velocity of the second high-order body wave and the value of (H2 / H1)×γ in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 0°, γ).

[0027] Fig. 9 A schematic diagram of the change between the normalized frequency difference between the first high-order bulk wave and the second high-order bulk wave and the (H2 / H1)×γ value in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 0°, γ).

[0028] Fig.10A schematic diagram of the relationship between the main mode admittance ratio of an elastic wave resonator and the (H2 / H1)×γ value when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 0°, γ).

[0029] Fig.11 A schematic diagram of the relationship between the wave velocity of the first high-order body wave and the wave velocity of the second high-order body wave and the value of (H2 / H1)×γ in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 90°, γ).

[0030] Fig.12 A schematic diagram of the change between the normalized frequency difference between the first high-order bulk wave and the second high-order bulk wave and the (H2 / H1)×γ value in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 90°, γ).

[0031] Fig.13 A schematic diagram of the relationship between the main mode admittance ratio of an elastic wave resonator and the (H2 / H1)×γ value when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 90°, γ).

[0032] Fig.14 A schematic diagram of the relationship between the wave velocity of the first high-order body wave and the wave velocity of the second high-order body wave and the (H2 / H1)×γ value in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 122.23°, γ).

[0033] Fig.15 A schematic diagram of the change between the normalized frequency difference between the first high-order bulk wave and the second high-order bulk wave and the (H2 / H1)×γ value in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 122.23°, γ).

[0034] Fig.16 A schematic diagram of the relationship between the main mode admittance ratio of an elastic wave resonator and the (H2 / H1)×γ value when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 122.23°, γ).

[0035] Fig.17 The present invention provides a phase-frequency characteristic curve of an elastic wave resonator provided by the prior art.

[0036] Fig.18 An admittance characteristic curve of an elastic wave resonator provided by an embodiment of the present invention.

[0037] Fig.19 A phase-frequency characteristic curve of an elastic wave resonator provided by an embodiment of the present invention.

[0038] Fig. 20Admittance characteristic curves of the main modes of the elastic wave resonator provided in the embodiment of the present invention and the elastic wave resonator provided in the prior art.

[0039] Fig.21 A cross-sectional schematic diagram of another elastic wave resonator provided in an embodiment of the present invention.

[0040] Fig. 22 A schematic diagram of the structure of an elastic wave filter provided by an embodiment of the present invention.

[0041] Fig.23 A schematic diagram of the structure of another elastic wave filter provided by an embodiment of the present invention.

[0042] Fig.24 A schematic structural diagram of an elastic wave multiplexer provided in an embodiment of the present invention.

[0043] Fig.25 A schematic structural diagram of a radio frequency front-end circuit provided in an embodiment of the present invention.

[0044] Explanation of the reference numerals: 10, elastic wave resonator; 11, substrate; 12, functional film layer; 13, piezoelectric layer; 14, interdigital transducer; 141, first interdigital electrode; 142, second interdigital electrode; 143, first pseudo-finger electrode; 144, second pseudo-finger electrode; 145, first bus bar; 146, second bus bar; 147, reflection grid; 111, C surface of sapphire crystal; 112, A surface of sapphire crystal; 113, R surface of sapphire crystal; 114, M surface of sapphire crystal; a1, a2 and a3, sapphire crystal three crystal axes on the C-plane 111; 15, capture layer; B1, the first high-order body wave of the existing elastic wave resonator; B2, the second high-order body wave of the existing elastic wave resonator; B3, the third high-order body wave of the existing elastic wave resonator; S1, the curve of the change of the wave velocity of the first high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (90°, 90°, γ) with the value of (H2 / H1)×γ; S2, the curve of the change of the wave velocity of the second high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (90°, 90°, γ) S3, the wave velocity of the first high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (0°, 0°, γ) and the wave velocity of the second high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (0°, 0°, γ) and the wave velocity of the second high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (0°, 0°, γ) and the wave velocity of the second high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (0°, 9 ... S6. The wave velocity of the first high-order body wave varies with the value of (H2 / H1)×γ; S7. The wave velocity of the first high-order body wave varies with the value of (H2 / H1)×γ in the elastic wave resonator when the Euler angle of the substrate provided by the embodiment of the present invention is (0°, 90°, γ); S8. The wave velocity of the second high-order body wave varies with the value of (H2 / H1)×γ in the elastic wave resonator when the Euler angle of the substrate provided by the embodiment of the present invention is (0°, 122.23°, γ); S9. The wave velocity of the first high-order body wave varies with the value of (H2 / H1)×γ in the elastic wave resonator when the Euler angle of the substrate provided by the embodiment of the present invention is (0°, 122.23°, γ);23°, γ) when the velocity of the second high-order body wave in the elastic wave resonator varies with the value of (H2 / H1)×γ; S9, the admittance characteristic curve of the main mode of the elastic wave resonator provided by the prior art; S10, the admittance characteristic curve of the main mode of the elastic wave resonator provided by the embodiment of the present invention; 20, elastic wave filter; in, signal input terminal; out, signal output terminal; 21, series arm resonator; 22, parallel arm resonator; 23, series-parallel resonator; DMS, dual-mode surface acoustic wave resonator; 30, elastic wave multiplexer; 31, antenna; 32. Receiving unit; 33. Transmitting unit; P1. Receiving terminal; P2. Transmitting terminal; 40. RF front-end circuit; 41. Switch; 42. First elastic wave filter; 43. Second elastic wave filter; 44. First duplexer transmitting filter; 45. First duplexer receiving filter; 46. Second duplexer transmitting filter; 47. Second duplexer receiving filter; 48. Low noise amplifier; 49. Power amplifier; 50. RF communication device; 51. Antenna terminal; 52. RF signal processing circuit; 53. Baseband signal processing circuit. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0046] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0047] Figure 1 A cross-sectional schematic diagram of an elastic wave resonator provided by an embodiment of the present invention, referring to Figure 1The elastic wave resonator 10 in the embodiment of the present invention includes a substrate 11, a functional film layer 12 disposed on one side of the substrate 11, a piezoelectric layer 13 disposed on a side of the functional film layer 12 away from the substrate 11, and an interdigital transducer 14 disposed on a side of the piezoelectric layer 13 away from the functional film layer 12. The substrate 11 includes a sapphire substrate. The piezoelectric layer 13 includes a lithium tantalate piezoelectric layer, and the frequency temperature coefficient of the functional film layer 12 is opposite to the polarity of the frequency temperature coefficient of the piezoelectric layer 13.

[0048] When the Euler angle of the substrate 11 is (90°, 90°, γ°), it satisfies: 7.5≤(H2 / H1)×γ≤300 or 30≤(H2 / H1)×γ≤480. When the Euler angle of the substrate 11 is (0°, 0°, γ°), it satisfies: 0≤(H2 / H1)×γ≤120 or 22.5≤(H2 / H1)×γ≤600. When the Euler angle of the substrate 11 is (0°, 90°, γ°), it satisfies: 10≤(H2 / H1)×γ≤240 or 30≤(H2 / H1)×γ≤510. When the Euler angle of the substrate 11 is (0°, 122.23°, γ°), it satisfies: 5≤(H2 / H1)×γ≤300 or 25≤(H2 / H1)×γ≤540. Wherein, H1=h1 / λ, H2=h2 / λ. λ represents the wavelength of the elastic wave in the elastic wave resonator 10, H1 represents the normalized thickness of the functional film layer 12, h1 represents the actual thickness of the functional film layer 12, H2 represents the normalized thickness of the piezoelectric layer 13, and h2 represents the actual thickness of the piezoelectric layer 13.

[0049] It should be noted that the value range of γ can be [0°~180°] or [-180°~0°]. [-180°~0°] is the equivalent angle value range of the angle range [0°~180°]. When the value range of γ is [-180°~0°], the above relationship is still satisfied after taking the absolute value of its angle.

[0050] As a feasible implementation, the actual thickness h1 of the functional film layer 12 satisfies 0.05λ≤h1≤1.2λ. The actual thickness h2 of the piezoelectric layer 13 satisfies 0.05λ≤h2≤5λ. The selection of the actual thickness h1 of the functional film layer 12 and the actual thickness h2 of the piezoelectric layer 13 can be determined according to the design requirements of the elastic wave resonator, and the embodiment of the present invention does not limit this.

[0051] For example, Figure 2 A schematic diagram of the structure of an interdigital transducer provided in an embodiment of the present invention, referring to Figure 2The IDT 14 includes a first interdigital electrode 141, a second interdigital electrode 142, a first dummy electrode 143, a second dummy electrode 144, a first bus bar 145, a second bus bar 146 and a reflector 147. The wavelength λ of the elastic wave in the elastic wave resonator 10 is determined by the period D of the IDT 14, and the period D of the IDT 14 refers to the distance between two adjacent first interdigital electrodes 141 or the distance between two adjacent second interdigital electrodes 142. The IDT 40 is made of any one of metals such as Al, Cu, Pt, Mo, Au, Cr, Ti, etc., or an alloy material formed by at least two of these metals.

[0052] The substrate 11 in the embodiment of the present invention adopts a sapphire substrate, whose normalized thickness is greater than 20λ, and belongs to a semi-infinite base structure. Sapphire crystal belongs to the trigonal system and is an anisotropic crystal, and its orientation is expressed by the Euler angle defined in the international standard "IEC62276, 2005-05, AnnexA1", which is expressed as (α, β, γ). Figure 3 The crystal structure diagram of the sapphire crystal used in the substrate provided in the embodiment of the present invention is shown in FIG. Figure 3 Typical crystal planes corresponding to sapphire crystal are C-plane 111, A-plane 112, R-plane 113, and M-plane 114. Three typical crystal axes a1, a2, and a3 are shown on C-plane 111. The Euler angles corresponding to C-plane 111 are (0°, 0°, γ), the Euler angles corresponding to A-plane 112 are (90°, 90°, γ), the Euler angles corresponding to R-plane 113 are (0°, 122.23°, γ), and the Euler angles corresponding to M-plane 114 are (0°, 90°, γ). The selection of γ angle determines the direction of the positioning edge of the sapphire crystal wafer, and the embodiment of the present invention defines it as being consistent with the propagation direction of the elastic wave.

[0053] As a feasible implementation manner, when the substrate 11 is a sapphire substrate whose main surface is the C-surface 111, the Euler angle of the substrate 11 can be (0°, 0°, 0°) or (0°, 0°, 30°) or (0°, 0°, 90°). When the substrate 11 is a sapphire substrate whose main surface is the A-surface 112, the Euler angle of the substrate 11 can be (90°, 90°, 60°) or (90°, 90°, 140°). When the substrate 11 is a sapphire substrate whose main surface is the M-surface 114, the Euler angle of the substrate 11 can be (0°, 90°, 60°) or (0°, 90°, 150°) or (0°, 90°, 155°). When the substrate 11 is a sapphire substrate whose main surface is the R-surface 113 , the Euler angle of the substrate 11 is (0°, 122.23°, 30°) or (0°, 122.23°, 60°) or (0°, 122.23°, 160°).

[0054] As a feasible implementation, the functional film layer 12 includes a silicon oxide layer and / or a silicon oxynitride layer. When the frequency temperature coefficient of the lithium tantalate piezoelectric layer is negative, the resonant frequency will decrease with increasing temperature; when the frequency temperature coefficients of the silicon oxide layer and the silicon oxynitride layer are positive, the resonant frequency will increase with increasing temperature. By setting the frequency temperature coefficient of the functional film layer 12 to have a polarity opposite to that of the piezoelectric layer 13, the effect of temperature on the resonant frequency can be reduced, which is beneficial to improving the performance of the elastic wave resonator.

[0055] As a feasible implementation, the frequency temperature coefficient TCV1 of the functional film layer 12 satisfies +20ppm / ℃≤TCV1≤+72ppm / ℃. It can be understood that the thickness of the lithium tantalate wafer (bulk material) used to make the lithium tantalate piezoelectric layer is relatively thick, and its frequency temperature coefficient is about -25ppm / ℃. The thickness of the lithium tantalate piezoelectric layer made of the lithium tantalate wafer is thinner, and since the thinner the thickness of the lithium tantalate piezoelectric layer, the lower its frequency temperature coefficient, that is, the higher the absolute value of its frequency temperature coefficient, the frequency temperature coefficient TCV2 of the lithium tantalate piezoelectric layer satisfies TCV2≤-25ppm / ℃. It can also be understood that the frequency temperature coefficient of the functional film layer 12 is also affected by its thickness. In the embodiment of the present invention, the absolute value of the frequency temperature coefficient of the functional film layer 12 can be made close to the absolute value of the frequency temperature coefficient of the lithium tantalate piezoelectric layer by adjusting the thickness of the functional film layer 12 and the lithium tantalate piezoelectric layer (i.e., the piezoelectric layer 13), which can further reduce the influence of temperature on the resonant frequency.

[0056] Optionally, the piezoelectric layer 13 includes a lithium tantalate piezoelectric layer, and the Euler angle of the lithium tantalate can be (0°, 35°~60°, 0°), (0°±10°, 35°~60°, 0°) or (0°, 35°~60°, 0°±10°). The specific Euler angle of lithium tantalate can be determined according to the actual device design requirements, and the embodiment of the present invention is not limited to this.

[0057] Due to the advantages of the insulating properties of the sapphire substrate, it is no longer necessary to set a capture layer in the stacked structure composed of a sapphire substrate, a silicon oxide layer and a lithium tantalate piezoelectric layer to solve the problems of nonlinear distortion (harmonics / intermodulation) of radio frequency signals, acoustic wave energy loss, crosstalk between adjacent devices, and deterioration of device quality factors. The elastic wave resonator in the prior art adopts a stacked structure composed of a single crystal silicon substrate, a silicon oxide insulating layer and a lithium tantalate layer. Due to the parasitic surface conductivity on the interface between the single crystal silicon substrate and the silicon oxide layer, the effective resistivity of the single crystal silicon substrate is reduced, thereby causing deterioration of the device quality factor and reduction of nonlinearity. The embodiment of the present invention can solve this problem by introducing a sapphire substrate with insulating properties.

[0058] Figure 4The present invention provides an admittance characteristic curve of an elastic wave resonator. The structure of the elastic wave resonator disclosed in the prior art includes a single crystal silicon substrate, a silicon oxide layer, a lithium tantalate piezoelectric layer and an interdigital transducer stacked in sequence, and the material of the interdigital transducer is metal Al. Figure 4 It can be seen that there are three parasitic body wave responses on the high-frequency side, namely the first high-order body wave B1, the second high-order body wave B2 and the third high-order body wave B3. These three parasitic responses will affect the attenuation of the high-frequency side of the elastic wave filter and the harmonic characteristics of the device (especially the second harmonic characteristics). These parasitic responses need to be suppressed.

[0059] The substrate 11 of the elastic wave resonator in the embodiment of the present invention is a sapphire substrate whose main surface is the A-surface 112, and its Euler angle is (90°, 90°, γ). The piezoelectric layer 13 is a lithium tantalate piezoelectric layer, and its Euler angle is (0°, 48°, 0°). The functional film layer 12 is a silicon oxide layer. The material used for the interdigital transducer 14 is metal Al. The wavelength λ of the elastic wave in the elastic wave resonator 10 is 2um. Figure 5 A schematic diagram of the relationship between the wave velocity of the first high-order body wave and the wave velocity of the second high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (90°, 90°, γ) and the value of (H2 / H1)×γ, wherein curve S1 is the wave velocity change curve of the first high-order body wave, and curve S2 is the wave velocity change curve of the second high-order body wave. Figure 6 A schematic diagram showing the change between the normalized frequency difference between the first high-order bulk wave and the second high-order bulk wave and the value of (H2 / H1)×γ in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (90°, 90°, γ). Figure 5 and Figure 6 It can be seen that the changing trends of the wave velocities of the first high-order body wave and the second high-order body wave are opposite to the increase of the (H2 / H1)×γ value. In the actual application of elastic wave filters, the appropriate (H2 / H1)×γ value can be selected according to the different requirements of the out-of-band suppression index to avoid the influence of high-order body waves on device performance.

[0060] Figure 7 A schematic diagram of the relationship between the main mode admittance ratio and the (H2 / H1)×γ value of the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (90°, 90°, γ). It can be understood that the magnitude of the main mode admittance ratio is positively correlated with the Q value of the elastic wave resonator. The larger the admittance ratio, the higher the Q value. The appropriate (H2 / H1)×γ value can be selected according to the requirements for the Q value. It should be noted that this embodiment only shows the situation under some (H2 / H1)×γ values.

[0061] The substrate 11 of the elastic wave resonator in the embodiment of the present invention is a sapphire substrate whose main surface is the C-surface 111, and its Euler angle is (0°, 0°, γ). The piezoelectric layer 13 is a lithium tantalate piezoelectric layer, and its Euler angle is (0°, 48°, 0°). The functional film layer 12 is a silicon oxide layer. The material used for the interdigital transducer 14 is metal Al. The wavelength λ of the elastic wave in the elastic wave resonator 10 is 2um. Figure 8 A schematic diagram of the relationship between the wave velocity of the first high-order body wave and the wave velocity of the second high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 0°, γ) and the value of (H2 / H1)×γ, wherein curve S3 is the wave velocity change curve of the first high-order body wave, and curve S4 is the wave velocity change curve of the second high-order body wave. Fig. 9 A schematic diagram showing the change between the normalized frequency difference between the first high-order bulk wave and the second high-order bulk wave and the value of (H2 / H1)×γ in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 0°, γ). Figure 8 and Fig. 9 It can be seen that the velocity of the first high-order body wave varies slightly with the (H2 / H1)×γ value, fluctuating around 5400m / s. The velocity of the second high-order body wave varies with the (H2 / H1)×γ value and shows a certain periodicity. In actual elastic wave filter applications, the appropriate (H2 / H1)×γ value can be selected according to different out-of-band suppression index requirements to avoid the influence of the second high-order body wave on device performance.

[0062] Fig.10 A schematic diagram of the relationship between the main mode admittance ratio and the (H2 / H1)×γ value of the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (0°, 0°, γ). It can be understood that the magnitude of the main mode admittance ratio is positively correlated with the Q value of the elastic wave resonator. The larger the admittance ratio, the higher the Q value. The appropriate (H2 / H1)×γ value can be selected according to the requirements for the Q value. It should be noted that this embodiment only shows the situation under some (H2 / H1)×γ values.

[0063] The substrate 11 of the elastic wave resonator in the embodiment of the present invention is a sapphire substrate whose main surface is the M-plane 114, and its Euler angle is (0°, 90°, γ). The piezoelectric layer 13 is a lithium tantalate piezoelectric layer, and its Euler angle is (0°, 48°, 0°). The functional film layer 12 is a silicon oxide layer. The material used for the interdigital transducer 14 is metal Al. The wavelength λ of the elastic wave in the elastic wave resonator 10 is 2um. Fig.11A schematic diagram of the relationship between the wave velocity of the first high-order body wave and the wave velocity of the second high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 90°, γ) and the value of (H2 / H1)×γ, wherein curve S5 is the wave velocity change curve of the first high-order body wave, and curve S6 is the wave velocity change curve of the second high-order body wave. Fig.12 A schematic diagram showing the change between the normalized frequency difference between the first high-order bulk wave and the second high-order bulk wave and the value of (H2 / H1)×γ in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 90°, γ). Fig.11 and Fig.12 It can be seen that the velocity of the first high-order body wave varies slightly with the (H2 / H1)×γ value, and varies in the range of about 5300~5500m / s, showing a certain periodicity. The velocity of the second high-order body wave is in the range of (H2 / H1)×γ value greater than 60, and shows a certain periodicity with the change trend of (H2 / H1)×γ value. In the actual application of elastic wave filters, the appropriate (H2 / H1)×γ value can be selected according to the different requirements of out-of-band suppression indicators to avoid the influence of the second high-order body wave on the device performance.

[0064] Fig.13 A schematic diagram of the relationship between the main mode admittance ratio and the (H2 / H1)×γ value of the elastic wave resonator when the Euler angle of the substrate provided in the embodiment of the present invention is (0°, 90°, γ). It can be understood that the size of the main mode admittance ratio is positively correlated with the Q value of the elastic wave resonator. The larger the admittance ratio, the higher the Q value. When the (H2 / H1)×γ value is below 150, the admittance ratio increases with the increase of the (H2 / H1)×γ value, that is, the Q value increases, which is beneficial to improving the performance of the elastic wave resonator. The appropriate (H2 / H1)×γ value can be selected according to the requirements for the Q value. It should be noted that this embodiment only shows the situation under some (H2 / H1)×γ values.

[0065] The substrate 11 of the elastic wave resonator in the embodiment of the present invention is a sapphire substrate whose main surface is the R-surface 113, and its Euler angle is (0°, 122.23°, γ). The piezoelectric layer 13 is a lithium tantalate piezoelectric layer, and its Euler angle is (0°, 48°, 0°). The functional film layer 12 is a silicon oxide layer. The material used for the interdigital transducer 14 is metal Al. The wavelength λ of the elastic wave in the elastic wave resonator 10 is 2um. Fig.14 A schematic diagram of the relationship between the wave velocity of the first high-order body wave and the wave velocity of the second high-order body wave in the elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 122.23°, γ) and the value of (H2 / H1)×γ, wherein curve S7 is the wave velocity change curve of the first high-order body wave, and curve S8 is the wave velocity change curve of the second high-order body wave. Fig.15A schematic diagram showing the change between the normalized frequency difference between the first high-order bulk wave and the second high-order bulk wave and the value of (H2 / H1)×γ in an elastic wave resonator when the Euler angle of the substrate provided in an embodiment of the present invention is (0°, 122.23°, γ). Fig.11 and Fig.12 It can be seen that the velocity of the first high-order body wave varies slightly with the (H2 / H1)×γ value, which varies in the range of about 5300~5500m / s, showing a certain periodicity. In the entire range of (H2 / H1)×γ values, the velocity of the second high-order body wave varies with the (H2 / H1)×γ value and shows a periodic trend. In the actual application of elastic wave filters, the position of the second high-order body wave on the electrical response curve of the elastic wave resonator can be adjusted by selecting the appropriate (H2 / H1)×γ value according to the out-of-band suppression index requirements.

[0066] Fig.16 A schematic diagram of the relationship between the main mode admittance ratio of the elastic wave resonator and the (H2 / H1)×γ value when the Euler angle of the substrate provided in the embodiment of the present invention is (0°, 122.23°, γ). It can be understood that the magnitude of the main mode admittance ratio is positively correlated with the Q value of the elastic wave resonator. The larger the admittance ratio, the higher the Q value. The admittance ratio shows a certain periodicity within the (H2 / H1)×γ value range shown in the figure. The appropriate (H2 / H1)×γ value can be selected according to the requirements for the Q value. It should be noted that this embodiment only shows the situation under some (H2 / H1)×γ values.

[0067] The structure of the elastic wave resonator provided by the prior art is basically the same as that of the elastic wave resonator provided by the embodiment of the present invention. The difference lies in the material of the substrate. The prior art uses a single crystal silicon substrate, while the embodiment of the present invention uses a sapphire substrate. The rest of the structure and its structural parameter settings are the same. Both use similar Figure 1 The form shown. Fig.17 A phase-frequency characteristic curve of an elastic wave resonator provided by the prior art, referring to Figure 4 and Fig.17 It can be seen that the elastic wave resonator provided by the prior art has serious high-order parasitic body wave response on the high-frequency side. Fig.18 An admittance characteristic curve of an elastic wave resonator provided by an embodiment of the present invention, Fig.19 A phase-frequency characteristic curve of an elastic wave resonator provided in an embodiment of the present invention is shown in FIG. Fig.18 and Fig.19 It can be seen that the elastic wave resonator provided by the embodiment of the present invention can weaken or suppress the response of the high-order parasitic body waves of the elastic wave resonator on the high-frequency side, and the third high-order body wave response is completely suppressed.

[0068] Fig. 20The main mode admittance characteristic curves of the elastic wave resonator provided by the embodiment of the present invention and the elastic wave resonator provided by the prior art are shown in FIG. 1 , wherein curve S9 is the main mode admittance characteristic curve of the elastic wave resonator provided by the prior art, and curve S10 is the main mode admittance characteristic curve of the elastic wave resonator provided by the embodiment of the present invention. Fig. 20 It can be seen that, compared with the elastic filter in the prior art, the main mode response of the elastic wave resonator in the embodiment of the present invention will not deteriorate, the resonant frequency of the elastic wave resonator in the embodiment of the present invention is higher than the resonant frequency of the elastic wave resonator in the prior art, and according to the relationship between the wave velocity V and the frequency f: V=λ×f, it can be seen that the main mode wave velocity of the elastic wave resonator in the embodiment of the present invention is higher than the main mode wave velocity of the elastic wave resonator in the prior art, and the electromechanical coupling coefficient of the elastic wave resonator in the embodiment of the present invention is greater than the electromechanical coupling coefficient of the elastic wave resonator in the prior art. Specifically, the main mode wave velocity of the elastic wave resonator in the embodiment of the present invention is 3810m / s, and the electromechanical coupling coefficient is 10.65%; the main mode wave velocity of the elastic wave resonator in the prior art is 3800m / s, and the electromechanical coupling coefficient is 10.4%.

[0069] The technical solution of the embodiment of the present invention can solve the problems of signal nonlinear distortion (harmonics / intermodulation), acoustic wave energy loss, crosstalk between adjacent devices, device quality factor deterioration, etc. that exist in the resonator due to the use of a single crystal silicon substrate by setting the substrate 11 to be an insulating sapphire substrate. There is no need to set a capture layer to absorb charge carriers that interfere with device performance in the field, which can simplify the manufacturing process and reduce costs. Moreover, by setting the substrate 11 to be a sapphire substrate, the response of high-order parasitic body waves of the elastic wave resonator on the high-frequency side can be weakened or suppressed. There is no need to arrange regular protrusions and / or recesses on the substrate or the insulating layer to achieve high-order parasitic mode suppression, which can further simplify the manufacturing process and reduce costs. By setting the substrate 11 to be a sapphire substrate, the elastic wave resonator can also have a higher wave speed and electromechanical coupling coefficient, which is conducive to the miniaturization and larger bandwidth of high-frequency devices.

[0070] Fig.21 A cross-sectional schematic diagram of another elastic wave resonator provided by an embodiment of the present invention, referring to Fig.21 The elastic wave resonator 10 further includes a capture layer 15, which is disposed between the substrate 11 and the functional film layer 12. The capture layer 15 is made of polycrystalline silicon, amorphous silicon, mesoporous silicon, silicon nitride or glass.

[0071] Exemplarily, the capture layer 15 may be an inversion carrier capture layer. In the embodiment of the present invention, the elastic wave resonator includes a substrate 11, a capture layer 15, a functional film layer 12, a piezoelectric layer 13, and an interdigital transducer 14 stacked in sequence. By providing the capture layer 15, the excess interfering charge carriers can be further absorbed, thereby further improving the performance of the elastic wave resonator 10.

[0072] refer to Fig.21 The elastic wave resonator 10 also includes a capture layer 15, which is arranged between the substrate 11 and the functional film layer 12. The actual thickness h3 of the capture layer 15 satisfies 0.05λ≤h3≤0.5λ. By setting the capture layer 15, the excess interfering charge carriers can be further absorbed, and the performance of the elastic wave resonator 10 can be further improved. The selection of the actual thickness h3 of the capture layer 15 can be determined according to the design requirements of the elastic wave resonator 10, and the embodiment of the present invention is not limited to this. It should be noted that H3=h3 / λ, and H3 represents the normalized thickness of the capture layer 15.

[0073] Based on the same inventive concept, an embodiment of the present invention further provides an elastic wave filter 20, which includes the elastic wave resonator 10 in the above embodiment. Therefore, the elastic wave filter 20 includes the technical features of the elastic wave resonator 10 and has the beneficial effects of the elastic wave resonator 10. For the similarities, please refer to the above description.

[0074] Fig. 22 A schematic diagram of the structure of an elastic wave filter provided by an embodiment of the present invention, referring to Fig. 22 The elastic wave filter 20 adopts a ladder topology elastic wave filter, including a signal input terminal in, a signal output terminal out, at least one series arm resonator 21 and at least one parallel arm resonator 22. The series arm resonator 21 and the parallel arm resonator 22 both adopt the elastic wave resonator 10 provided by any of the above embodiments of the present invention. The number of series arm resonators 21 is the same as or different from the number of parallel arm resonators 22. Exemplarily, a series arm resonator 21 and a parallel arm resonator 22 can be defined as a group of series-parallel resonators 23. The elastic wave filter 20 may include at least one series-parallel resonator 23, and each series-parallel resonator 23 is sequentially connected in series between the signal input terminal in and the signal output terminal out. It should be noted that Fig. 22 The number of the series-parallel resonators 23 shown is 4, and this embodiment is only an example and is not limiting.

[0075] Fig.23 A schematic diagram of another elastic wave filter provided by an embodiment of the present invention, referring to Fig.23The elastic wave filter adopts a longitudinally coupled resonator type elastic wave filter, including a signal input terminal in, a signal output terminal out, at least one dual-mode surface acoustic wave resonator DMS, at least one series arm resonator 21 and at least one parallel arm resonator 22, and the series arm resonator 21 and the parallel arm resonator 22 both adopt the elastic wave resonator 10 provided by any of the above embodiments of the present invention. At least one dual-mode surface acoustic wave resonator DMS, at least one series arm resonator 21 and at least one parallel arm resonator 22 are electrically connected between the signal input terminal in and the signal output terminal out. The position of the dual-mode surface acoustic wave resonator DMS between the input terminal and the output terminal is not limited. The series arm resonator 21 is connected in series between the signal input terminal in and the signal output terminal out, one end of the parallel arm resonator 22 is connected between the signal input terminal in and the signal output terminal out, and the other end of the parallel arm resonator 22 is grounded. It should be noted that the number of dual-mode surface acoustic wave resonators DMS and the series arm resonator 21 and the number of parallel arm resonators 22 can be the same or different. Fig. 22 The number of the series arm resonators 21 and the number of the parallel arm resonators 22 shown are both 2, and the number of the dual-mode surface acoustic wave resonators DMS is 1. This embodiment is only an example and is not limiting.

[0076] Based on the same inventive concept, an embodiment of the present invention further provides an elastic wave multiplexer 30, Fig.24 A schematic diagram of the structure of an elastic wave multiplexer provided in an embodiment of the present invention, referring to Fig.24 The elastic wave multiplexer 30 in the embodiment of the present invention includes an antenna 31, at least one receiving unit 32 and at least one transmitting unit 33. The antenna 31 is respectively connected to the receiving unit 32 and the transmitting unit 33 for communication. At least one of the receiving unit 32 and the transmitting unit 33 includes the elastic wave filter 20 in the above embodiment. Therefore, the elastic wave multiplexer 30 includes the technical features of the elastic wave filter 20 and has the beneficial effects of the elastic wave filter 20. The similarities can be referred to the above description.

[0077] For example, the elastic wave multiplexer 30 is an elastic wave duplexer. The receiving unit 32 is arranged between the antenna 31 and the receiving terminal P1, and forms a first passband of the elastic wave duplexer. The transmitting unit 33 is arranged between the antenna 31 and the transmitting terminal P2, and forms a second passband of the elastic wave duplexer. It should be noted that the receiving unit 32 may include: Fig. 22 The ladder topology elastic wave filter shown in FIG. 1 may also include Fig.23 The longitudinally coupled resonator type elastic wave filter shown in FIG. 3 may include a transmitting unit 33 as shown in FIG. Fig. 22 The ladder topology elastic wave filter shown in FIG. 1 may also include Fig.23The longitudinally coupled resonator type elastic wave filter shown.

[0078] It can be understood that when the elastic wave multiplexer 30 is a quadplexer, the quadplexer includes four terminals, an antenna, and four elastic wave filters 20, a passband is formed between each terminal and the antenna, and at least one of the four elastic wave filters 20 includes the elastic wave resonator 10 in the above embodiment.

[0079] Based on the same inventive concept, an embodiment of the present invention further provides a radio frequency front-end circuit 40, Fig.25 A schematic diagram of a radio frequency front-end circuit according to an embodiment of the present invention is provided. Fig.25 The radio frequency front-end circuit 40 in the embodiment of the present invention includes the elastic wave multiplexer 30 in the above embodiment.

[0080] refer to Fig.25 The RF front-end circuit 40 includes a switch 41, a first elastic wave filter 42, a second elastic wave filter 43, a first duplexer (the first duplexer includes a first duplexer transmit filter 44 and a first duplexer receive filter 45), a second duplexer (the second duplexer includes a second duplexer transmit filter 46 and a second duplexer receive filter 47), a low noise amplifier 48 and a power amplifier 49.

[0081] Specifically, the RF front-end circuit 40 is connected to the RF signal processing circuit 52 and the baseband signal processing circuit 53 to form the RF communication device 50 .

[0082] Furthermore, the switch 41 is used to control the RF signal, connecting the antenna terminal 51 to at least one signal path corresponding to a given frequency band, and the at least one signal path connected to the antenna terminal 51 may also be multiple signal paths (corresponding to multiple filters and duplexers). The RF front-end circuit 40 can support carrier aggregation technology; the low noise amplifier 48 amplifies the RF signal fed via the antenna terminal 51, the switch 41, the first duplexer receiving filter 45, and the second duplexer receiving filter 47, and feeds the amplified signal to the RF signal processing circuit 52; the power amplifier 49 amplifies the RF signal provided by the RF signal processing circuit 52 and feeds the amplified signal to the antenna terminal 51 via the first duplexer transmitting filter 44, the second duplexer transmitting filter 46, and the switch 41 for transmission.

[0083] The RF signal processing circuit 52 in the RF communication device 50 performs signal processing on the RF receiving signal provided from the antenna terminal 51 via the receiving signal path, and feeds the receiving signal generated by the signal processing; and the RF signal processing circuit 52 performs signal processing on the fed transmitting signal, and feeds the RF transmitting signal generated by the signal processing to the power amplifier 49.

[0084] The RF front-end circuit 40 further includes a first elastic wave filter 42 and a second elastic wave filter 43 . The first elastic wave filter 42 and the second elastic wave filter 43 are connected between the RF signal processing circuit 52 and the switch 41 without passing through the low noise amplifier 48 or the power amplifier 49 .

[0085] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An elastic wave resonator, characterized in that: include: Substrates, including sapphire substrates; A functional film layer is disposed on one side of the substrate; A piezoelectric layer, comprising a lithium tantalate piezoelectric layer, wherein the piezoelectric layer is disposed on a side of the functional film layer away from the substrate; The polarity of the frequency temperature coefficient of the functional film layer is opposite to that of the frequency temperature coefficient of the piezoelectric layer; An interdigital transducer is arranged on a side of the piezoelectric layer away from the functional film layer; When the Euler angle of the substrate is (90°, 90°, γ°), it satisfies: 7.5≤(H2 / H1)×γ≤300 or 30≤(H2 / H1)×γ≤480; When the Euler angle of the substrate is (0°, 0°, γ°), it satisfies: 0≤(H2 / H1)×γ≤120 or 22.5≤(H2 / H1)×γ≤600; When the Euler angle of the substrate is (0°, 90°, γ°), it satisfies: 10≤(H2 / H1)×γ≤240 or 30≤(H2 / H1)×γ≤510; When the Euler angle of the substrate is (0°, 122.23°, γ°), it satisfies: 5≤(H2 / H1)×γ≤300 or 25≤(H2 / H1)×γ≤540; Among them, H1=h1 / λ; H2=h2 / λ; λ represents the wavelength of the elastic wave in the elastic wave resonator; H1 represents the normalized thickness of the functional film layer, and h1 represents the actual thickness of the functional film layer; H2 represents the normalized thickness of the piezoelectric layer, and h2 represents the actual thickness of the piezoelectric layer.

2. The elastic wave resonator according to claim 1, characterized in that: The actual thickness h1 of the functional film layer satisfies 0.05λ≤h1≤1.2λ; The actual thickness h2 of the piezoelectric layer satisfies 0.05λ≤h2≤5λ.

3. The elastic wave resonator according to claim 1, characterized in that: The frequency temperature coefficient TCV1 of the functional film layer satisfies +20ppm / °C≤TCV1≤+72ppm / °C.

4. The elastic wave resonator according to claim 3, characterized in that: The functional film layer includes a silicon oxide layer and / or a silicon oxynitride layer.

5. The elastic wave resonator according to claim 1, characterized in that: The Euler angle of the substrate is (0°, 0°, 0°) or (0°, 0°, 30°) or (0°, 0°, 90°); Alternatively, the Euler angle of the substrate is (90°, 90°, 60°) or (90°, 90°, 140°); Alternatively, the Euler angle of the substrate is (0°, 90°, 60°) or (0°, 90°, 150°) or (0°, 90°, 155°); Alternatively, the Euler angle of the substrate is (0°, 122.23°, 30°) or (0°, 122.23°, 60°) or (0°, 122.23°, 160°).

6. The elastic wave resonator according to claim 1, characterized in that: The elastic wave resonator further comprises a capture layer, wherein the capture layer is arranged between the substrate and the functional film layer; The capture layer is made of polysilicon, amorphous silicon, mesoporous silicon, silicon nitride or glass.

7. The elastic wave resonator according to claim 1, characterized in that: The elastic wave resonator further comprises a capture layer, wherein the capture layer is arranged between the substrate and the functional film layer; The actual thickness h3 of the capture layer satisfies 0.05λ≤h3≤0.5λ.

8. An elastic wave filter, characterized in that: Comprising the elastic wave resonator as described in any one of claims 1 to 7.

9. An elastic wave multiplexer, characterized in that: comprising an antenna, at least one receiving unit and at least one transmitting unit; The antenna is communicatively connected to the receiving unit and the sending unit respectively; At least one of the receiving unit and the transmitting unit includes the elastic wave filter according to claim 8.

10. A radio frequency front-end circuit, characterized in that: Comprises the elastic wave multiplexer as described in claim 9.

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