Resonator, method of manufacturing the same, filter, electronic device

Abstract

A resonator (100) and its fabrication method, filter, and electronic device are disclosed, relating to the field of resonators, capable of suppressing spurious emissions on the admittance curve of the resonator. The resonator (100) includes: a substrate (S) and a transducer (T) disposed on the substrate (S); the transducer (T) includes a first electrode (a1), a piezoelectric layer (a3), and a second electrode (a2) stacked thereon; the second electrode (a2) is closer to the substrate (S) than the first electrode (a1); the first electrode (a1) includes a first edge (e1), and the piezoelectric layer (a3) ​​includes a second edge (e2); the first edge (e1) and the second edge (e2) are flush.

Description

Technical Field

[0001] This application relates to the field of resonator technology, and in particular to a resonator and its manufacturing method, a filter, and electronic equipment. Background Technology

[0002] Many stray particles often appear on the admittance curve of a resonator. These stray particles can affect the performance of the resonator, which in turn can cause in-band ripple in the filter composed of resonators and degrade the passband performance. Summary of the Invention

[0003] This application provides a resonator and its manufacturing method, a filter, and an electronic device, which can reduce stray emissions from the resonator.

[0004] This application provides a resonator including: a substrate and a transducer disposed on the substrate; the transducer includes a first electrode, a piezoelectric layer and a second electrode stacked thereon; the second electrode is close to the substrate relative to the first electrode; the first electrode includes a first edge and the piezoelectric layer includes a second edge, the first edge and the second edge are disposed flush with each other; that is, the first electrode and the piezoelectric layer have flush edge portions.

[0005] In the resonator provided in this application, by setting the edges of the piezoelectric layer and the upper electrode (i.e., the first electrode) to be flush (i.e. forming a flush boundary or a steep boundary), the transverse mode wave is reflected at the flush boundary, thereby generating a broadband piston mode (BPM) at the flush boundary, suppressing the generation of transverse modes in a wide frequency range and reducing spurious signals.

[0006] In some possible implementations, the portion of the piezoelectric layer flush with the edge of the first electrode is also flush with the edge of the second electrode. In this case, compared to the edge of the second electrode protruding from the edge of the piezoelectric layer, the resonator has a higher reflection coefficient (reflected wave amplitude / incident wave amplitude) through the portion of the piezoelectric layer flush with the first electrode, i.e., less energy loss, thereby improving the suppression of transverse modes.

[0007] In some possible implementations, the flush portions of the edges of the first electrode, the piezoelectric layer, and the second electrode constitute the first side region of the transducer; the resonator further includes a groove disposed on the substrate and located outside the first side region of the transducer; the opening edge of the groove on the side of the transducer near the first side region is flush with the edge of the second electrode. In this case, the arrangement of the groove is equivalent to further increasing the depth of the flush edge of the resonator, thereby reducing energy loss and further suppressing the generation of transverse mode strays.

[0008] In some possible implementations, the angle between the sidewall of the groove near the first side region of the transducer and the perpendicular line of the substrate is 0 to 25°; so that the phase of the reflection coefficient is close to 0 in a wider frequency range, ensuring that the sidewall of the groove near the first side region of the transducer can suppress transverse modes.

[0009] In some possible implementations, the sidewall of the groove on the side of the transducer near the first side region is perpendicular to the substrate.

[0010] In some possible implementations, the groove is a strip-shaped groove that extends along the first side region of the transducer.

[0011] In some possible implementations, the groove is filled with at least one of silicon oxide and silicon nitride.

[0012] In some possible implementations, the polarization direction of the piezoelectric material in the piezoelectric layer adopts the X-tangential or Y-tangential direction to improve the electromechanical coupling coefficient (k) of the resonator. 2 ).

[0013] In some possible implementations, the substrate has a cavity at the location of the transducer; in this case, the resonator is a thin-film bulk acoustic resonator.

[0014] In some possible implementations, the substrate includes a substrate and a reflective layer disposed on the substrate; the transducer is disposed on the surface of the reflective layer opposite to the substrate; in this case, the resonator is a solid-state reflective resonator.

[0015] This application also provides a filter, including a resonator as provided in any of the aforementioned possible implementations.

[0016] This application also provides an electronic device, including a transceiver, a memory, and a processor; wherein the transceiver is provided with a resonator as provided in any of the aforementioned possible implementations.

[0017] This application also provides a method for manufacturing a resonator, including:

[0018] A substrate is provided, and a first metal film layer, a piezoelectric layer, and a second metal film layer are sequentially formed on the substrate; the second metal film layer is patterned, and the film layer located in at least a portion of the edge region of the second metal film layer is removed to form an edge removal area; a protective film is formed on the surface of the patterned second metal film layer, and a cutout is formed on the protective film at the position corresponding to the edge removal area; wherein, the sidewall of the cutout exposes the side of the second metal film layer facing the edge removal area; a groove is formed at the position of the cutout.

[0019] The resonator fabrication method provided in this application involves fabricating a piezoelectric layer and an upper electrode (i.e., the first electrode) with partially flush edges (i.e., forming a flush boundary or a steep boundary). Transverse mode waves are reflected at the flush boundary, thereby generating a broadband piston mode (BPM) at the flush boundary. This suppresses the generation of transverse modes and reduces spurious emissions over a wide frequency range. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application;

[0021] Figure 2 A schematic diagram of the structure of a resonator provided in an embodiment of this application;

[0022] Figure 3 A schematic diagram of a resonator provided in an embodiment of this application;

[0023] Figure 4a This is a schematic diagram of the transducer structure in a resonator provided in an embodiment of this application;

[0024] Figure 4b This is a schematic diagram of the transducer structure in a resonator provided in an embodiment of this application;

[0025] Figure 4c This is a schematic diagram of the transducer structure in a resonator provided in an embodiment of this application;

[0026] Figure 5 A schematic diagram of a resonator provided in an embodiment of this application;

[0027] Figure 6a A schematic diagram of the structure of a resonator provided in an embodiment of this application;

[0028] Figure 6b A schematic diagram of the structure of a resonator provided in an embodiment of this application;

[0029] Figure 6c A schematic diagram of a resonator provided in an embodiment of this application;

[0030] Figure 7 A schematic diagram of the structure of a resonator provided in an embodiment of this application;

[0031] Figure 8 Admittance curves for resonators with different groove sidewall tilt angles provided in embodiments of this application;

[0032] Figure 9 Admittance curves for resonators with different groove depths provided in embodiments of this application;

[0033] Figure 10 An admittance curve of TSBAR under BPM is provided for an embodiment of this application;

[0034] Figure 11 This provides an admittance curve for TSBAR under PM in related technologies;

[0035] Figure 12 A Q-value curve of TSBAR under BPM is provided for embodiments of this application;

[0036] Figure 13 This provides a Q-value curve for TSBAR under PM in related technologies;

[0037] Figure 14 A Q-value curve of SMR under BPM is provided for an embodiment of this application;

[0038] Figure 15 This provides a Q-value curve for SMR under PM conditions in related technologies.

[0039] Figure 16 A schematic diagram of the structure of a resonator provided in an embodiment of this application;

[0040] Figure 17 A schematic diagram of the structure of a resonator provided in an embodiment of this application;

[0041] Figure 18 This is a structural schematic diagram illustrating the fabrication process of a resonator according to an embodiment of this application.

[0042] Figure 19 This is a structural schematic diagram illustrating the fabrication process of a resonator according to an embodiment of this application.

[0043] Figure 20 This is a structural schematic diagram illustrating the fabrication process of a resonator according to an embodiment of this application.

[0044] Figure 21 This is a structural schematic diagram illustrating the fabrication process of a resonator according to an embodiment of this application.

[0045] Figure 22 This is a structural schematic diagram illustrating the fabrication process of a resonator according to an embodiment of this application.

[0046] Figure 23 This is a structural schematic diagram illustrating the fabrication process of a resonator according to an embodiment of this application.

[0047] Figure 24 This is a schematic diagram of the structure of a filter provided in an embodiment of this application. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0049] The terms "first," "second," etc., used in the specification, embodiments, claims, and drawings of this application are for distinguishing purposes only and should not be construed as indicating or implying relative importance or order. "At least one" means one or more, and "more than" means two or more. Terms such as "connected," "linked," etc., are used to express communication or interaction between different components and may include direct connection or indirect connection through other components. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or device is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices. Terms such as "upper," "lower," "left," and "right," etc., are used only with respect to the orientation of components in the drawings. These directional terms are relative concepts used for relative description and clarification and may vary accordingly depending on the orientation of the components in the drawings.

[0050] This application provides an electronic device in which a filter is provided to suppress interference signals and achieve the purpose of filtering.

[0051] As illustrated, in some possible implementation methods, such as Figure 1 As shown, the above-mentioned electronic device 01 may include a transceiver 1, a memory 2, and a processor 3 (which may be a local processor or a cloud processor); wherein, the transceiver 1 is provided with a filter 10, which is constructed using a resonator.

[0052] This application does not limit the specific configuration of the aforementioned electronic device. For example, the electronic device can be a television set, a mobile phone, a satellite communication device, a cable television, etc.

[0053] In the filter of this application, the transverse mode (TM) spurious waves generated by the resonator can be suppressed, thereby enabling the resonant frequency (fr) and anti-resonant frequency (fa) of the resonator to have a smoother admittance curve, which in turn significantly reduces the passband ripple of the filter and improves the passband performance of the filter.

[0054] This application provides a resonator, which can be a piezoelectric thin-film bulk acoustic wave (BAW) resonator. This resonator, due to its high performance, small size, and high power tolerance, is widely used in radio frequency integrated circuits (RFICs) of terminal devices such as mobile phones. When the BAW resonator vibrates in its dominant mode, the acoustic wave only has a vertical propagation component. However, when a horizontal propagation component appears, transverse mode spurious signals other than the dominant resonant mode are generated. The resonator provided in this application can suppress transverse mode spurious signals, resulting in a smoother admittance curve between the resonant frequency (fr) and the anti-resonant frequency (fa), significantly reducing the passband ripple of the filter and improving its passband performance.

[0055] The following provides a further explanation of the specific configuration of the resonator provided in the embodiments of this application.

[0056] like Figure 2 , Figure 3 As shown, the resonator 100 includes a substrate S and a transducer T disposed on the substrate S; the transducer T includes a first electrode a1, a piezoelectric layer a3, and a second electrode a2 stacked on the substrate S; wherein the second electrode a2 is closer to the substrate S than the first electrode a1; that is, the second electrode a2, the piezoelectric layer a3, and the first electrode a1 are stacked on the substrate S in sequence, the first electrode a1 serves as the upper electrode of the transducer T, and the second electrode a2 serves as the lower electrode of the transducer T.

[0057] This application does not limit the shape of the first electrode a1 and the second electrode a2. For example, they can be rectangular, polygonal, circular, elliptical, or other shapes.

[0058] Furthermore, this application does not limit the conductive materials used for the first electrode a1 and the second electrode a2. For example, one or more of the following metal materials can be used: aluminum (Al), gold (Au), silver (Ag), copper (Cu), molybdenum (Mo), tungsten (W); the conductive materials used for the first electrode a1 and the second electrode a2 can be the same or different, and this application does not limit either of these.

[0059] As illustrated, the piezoelectric layer a3 can be one or more of the following piezoelectric materials: lithium niobate (LiNbO3), lithium tantalate (LiTaO3), and aluminum nitride (AlN); this application does not impose any restrictions on this, and the appropriate material can be selected as needed in practice.

[0060] Furthermore, with the advent of the 5G (5th generation mobile networks) era, in order to ensure the resonator's compatibility with high-frequency, high-bandwidth frequency bands (such as N77, N78, N79) and high electromechanical coupling coefficient (k... 2 To meet the requirements, in some possible implementation methods, the frequency range corresponding to the thickness shear mode (TSM) of the resonator 100 can be used, that is, the vibration mode of the piezoelectric layer 13 can be the frequency range corresponding to the thickness shear mode, in order to obtain a higher operating frequency and a larger electromechanical coupling coefficient (k). 2 ).

[0061] Of course, in order to further improve the electromechanical coupling coefficient (k 2 In some possible implementations, the polarization direction of the piezoelectric material in the piezoelectric layer of the resonator 100 can be either the X-tangent direction or the Y-tangent direction; for example, the piezoelectric material in the piezoelectric layer a3 can be at least one of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3), and the polarization direction of LiNbO3 and LiTaO3 can be either the X-tangent direction or the Y-tangent direction.

[0062] It is understandable that the polarization direction of the piezoelectric material can be either the X-axis or the Y-axis. Taking LiNbO3 as an example of the piezoelectric material in piezoelectric layer 13, and setting the crystal axis (X, Y, Z) of LiNbO3, in this case, refer to... Figure 6a As shown, the polarization direction of LiNbO3 using the X-tangent direction refers to the direction in which the X crystal axis of LiNbO3 faces the S normal of the substrate (i.e., the z-axis direction); the polarization direction of LiNbO3 using the Y-tangent direction refers to the direction in which the Y crystal axis of LiNbO3 faces the S normal of the substrate (i.e., the z-axis direction).

[0063] Furthermore, the resonator 100 in this application is not limited to a certain type, and can be configured as needed in practice.

[0064] Schematic, in some possible implementations, the resonator 100 can be a thin-film bulk acoustic wave resonator (FBAR); in this case, such as Figure 2As shown, a cavity C is provided on the substrate S of the resonator 100 at the position corresponding to the transducer T. The cavity C can be filled with air or a low acoustic resistance dielectric material. The substrate S can be made of semiconductor materials such as high-resistivity silicon, doped single-crystal silicon, polycrystalline silicon, silicon carbide, or diamond. Of course, an FBAR operating in the thickness shear mode can also be called a thickness shearbulk acoustic wave resonator (TSBAR).

[0065] Schematic, in some possible implementations, the resonator 100 can be a solid-mounted resonator (SMR); in this case, such as Figure 3 As shown, the substrate S in the resonator 100 includes a substrate 101 and a reflective layer 102 (also called a Bragg reflective layer) disposed on the substrate 101. The transducer T is disposed on the upper surface of the reflective layer 102 (i.e., the surface facing away from the substrate 101). The reflective layer 102 is formed by alternating low acoustic impedance layers b1 and high acoustic impedance layers b2 to reflect sound waves and limit energy. Schematic, the low acoustic impedance layer b1 can be made of a low acoustic impedance dielectric material, such as silicon dioxide (SiO2) or silicon nitride (SiN); the high acoustic impedance layer b2 can be made of a high acoustic impedance metal or dielectric material; the high acoustic impedance metal material can be such as tungsten (W) or molybdenum (Mo), and the high acoustic impedance dielectric material can be such as aluminum nitride (AlN) or tantalum pentoxide (Ta2O5); the substrate 101 can be made of high-resistivity silicon, doped single-crystal silicon, polycrystalline silicon, silicon carbide, diamond, or other semiconductor materials.

[0066] The following embodiments of this application use LiNbO3 with the resonator 100 operating in the thickness shear mode (TSM) as an example, and the piezoelectric layer polarization direction is either X-tangential or Y-tangential.

[0067] refer to Figure 2 and Figure 3 In the dashed area Z in the resonator 100, the first electrode a1 includes a first edge e1, the piezoelectric layer a3 includes a second edge e2, and the first edge e1 of the first electrode a1 and the second edge e2 of the piezoelectric layer a3 are flush; that is, the edges of the first electrode a1 and the edges of the piezoelectric layer a3 have a portion that is flush.

[0068] in, Figure 2 and Figure 3This illustration is merely based on the example of the first electrode a1 and the piezoelectric layer a3 having a side that is flush with each other. However, this application is not limited to this. It is possible for a portion of the edge area of ​​a side to be flush with each other, or for a portion or all of the edges of multiple sides to be flush with each other. In practice, the arrangement can be made as needed.

[0069] In addition, for the second electrode a2, the piezoelectric layer a3 can be configured such that the flush edges (i.e., the first edge e1 and the second edge e2) of the first electrode a1 do not protrude beyond the edge of the second electrode a2.

[0070] As shown in the illustration, among some possible implementation methods, see reference. Figure 4a The dashed area Z in the diagram corresponds to the second edge e2 of the piezoelectric layer a3, and the edge of the second electrode a2 can protrude beyond the second edge e2 of the piezoelectric layer a3.

[0071] As shown in the illustration, among some possible implementation methods, see reference. Figure 4b , Figure 4c The dashed area Z in the diagram corresponds to the location of the second edge e2 of the piezoelectric layer a3. The edge of the second electrode a2 includes a third edge e3 that is flush with the second edge e2.

[0072] In this case, such as Figure 4b As shown, in some possible implementations, the third edge e3 can be set flush with all the second edges e2; for example... Figure 4c As shown, in some possible implementations, the third edge e3 can be set flush with part of the second edge e2; this application does not impose specific restrictions on this, and it can be set as needed in practice.

[0073] Regarding the "flush" edge arrangement of the two film layers involved in this application, it is understood that due to limitations in the manufacturing process, it is difficult to achieve absolute flushness between the edges of two different film layers during fabrication. Steps can easily form at the edges, where the edge of the lower film layer may slightly protrude beyond the edge of the upper film layer by a certain distance (e.g., 0.5 μm), or vice versa. In other words, there may be a certain distance (e.g., within 0.5 μm) between the edges of the two film layers. In this case, the edges of the two film layers should be considered flush (or substantially flush). For example, the portion of the distance between the edges of the first electrode a1 and the piezoelectric layer a3 within 0.5 μm can be considered as flush edge portions. The term "flush" as used below will be understood in this manner and will not be elaborated further.

[0074] In summary, in the resonator provided in this application embodiment, by setting the edges of the piezoelectric layer and the upper electrode (i.e., the first electrode) to be flush (i.e., forming a flush boundary or a steep boundary), when the resonator operates in the thickness shear mode, the transverse mode wave is reflected at the flush boundary, and the phase difference between the incident angle and the reflection angle is close to 0. The standing wave formed by the superposition of the incident wave and the reflected wave is the antinode of the vibration wave at the flush boundary. When the transverse wave is the antinode of the vibration wave at both ends, the positive and negative charges of other higher-order transverse modes besides the fundamental mode can cancel each other out. That is, the electromechanical coupling coefficient of other higher-order transverse modes besides the fundamental mode is close to 0 (when the coupling coefficient is close to 0, the mode cannot be excited or induced by the electric field). Thus, a wide frequency range of tens to hundreds of MHz can be achieved in the 0±10° reflection angle frequency range at the flush boundary, and a broadband piston mode (BPM) is generated at the flush boundary, suppressing the generation of transverse modes in a large frequency range.

[0075] It should be noted here that at the flush edge between the piezoelectric layer a3 and the first electrode a1 (i.e., the first edge e1 and the second edge e2), compared to Figure 4a The edge of the second electrode a2 shown in the figure protrudes beyond the second edge e2 of the piezoelectric layer a3. Figure 4b In the scheme shown, where the second edge e2 of the second electrode a2 is flush with the third edge e3 of the piezoelectric layer a3, the resonator has a higher reflection coefficient (reflected wave amplitude / incident wave amplitude), less energy loss, and a wide frequency range of several MHz that can be achieved for the 0°±10° reflection angle, thereby improving the suppression of transverse modes.

[0076] refer to Figure 5 As shown, in this application, the region where the edges of the first electrode a1, piezoelectric layer a3, and second electrode a2 in the transducer T are flush is defined as the first side region A1. Based on this, the resonator 100 may further include a groove 103 disposed on the substrate S and located outside the first side region A1 of the transducer T; wherein the opening edge m1 of the groove 103 near the first side region A1 is flush with the edge of the second electrode a2; in this case, the arrangement of the groove 103 effectively increases the depth of the flush edge of the resonator 100, thereby reducing energy loss and further suppressing the generation of transverse modes.

[0077] refer to Figure 5As shown, the fact that the opening edge m1 of the groove 103 on the side near the first side region A1 is flush with the edge of the second electrode a2 does not mean that the opening edge m1 of the groove 103 on the side near the first side region A1 of the resonator 100 is absolutely flush with the edge of the second electrode a2 (refer to the aforementioned explanation of "flush"). It can be considered that the distance between the opening edge m1 of the groove 103 on the side near the first side region A1 of the resonator 100 and the edge of the second electrode a2 is less than or equal to 0.5 μm. That is, the opening edge m1 of the groove 103 on the side near the first side region A1 of the resonator 100 can be located inside the edge of the second electrode a2 (that is, part of the groove 103 is located below the second electrode a2), and the distance between it and the edge of the second electrode a2 is less than or equal to 0.5 μm; the opening edge m1 of the groove 103 on the side near the first side region A1 of the resonator 100 can also be located outside the edge of the second electrode a2, and the distance between it and the edge of the second electrode a2 is less than or equal to 0.5 μm.

[0078] It should be noted that the transducer T can have one first side region A1, or it can have multiple first side regions A1 (e.g., Figure 6a The two first side regions A1 are shown in the image. Additionally, as shown... Figure 6a As shown, one side of the transducer T can be entirely set as the first side region A1; as Figure 4c As shown, a portion of one side of the transducer T can be configured as the first side region A1.

[0079] This application does not impose any restrictions on the specific shape, size, or number of the grooves 103 mentioned above; in practice, they can be set as needed.

[0080] Indicative, such as Figure 6a As shown, the groove 103 can be a strip-shaped groove structure; as Figure 6b As shown, the groove 103 can be a rectangular groove structure; as Figure 6c As shown, the groove 103 can be a circular groove structure.

[0081] As illustrated, the substrate S may have one or more grooves 103 on the side corresponding to a single first side region A1.

[0082] For example, such as Figure 6a As shown, the substrate S may have a strip-shaped groove 103 provided on the side of a single first side region A1, and the strip-shaped groove 103 extends along the direction of the first side region A1.

[0083] For example, such as Figure 6b , Figure 6cAs shown, the substrate S can have multiple grooves 103 formed on the side of a single first side region A1.

[0084] Additionally, refer to Figure 7 As shown, it can be understood that for the resonator, when the transverse mode wave is reflected by the sidewall w1 of the groove 103 near the first side region A1, the tilt angle α of the sidewall w1 (that is, the angle between the sidewall w1 and the perpendicular line of the substrate S) will affect the phase and amplitude of the acoustic wave reflection coefficient; that is, the tilt angle α of the sidewall w1 directly determines the suppression effect on the transverse mode.

[0085] Based on this, in order to make the phase of the reflection coefficient close to 0 over a wider frequency range, and to ensure that the sidewall w1 of the groove 103 near the first side region A1 of the transducer T can suppress the transverse modes, some possible implementation methods include, Figure 7 As shown, the inclination angle α of the side wall w1 of the groove 103 near the first side region A1 can be set to 0 to 25°; or it can be said that the angle β between the side wall w1 of the groove 103 near the first side region A1 of the transducer T and the plane where the groove is located is within the range of 90°±25° (that is, 65° to 115°).

[0086] As illustrated, in some possible implementation methods, such as Figure 5 As shown, the inclination angle α of the aforementioned sidewall w1 can be 0°, that is, β = 90°.

[0087] As illustrated, in some possible implementation methods, such as Figure 7 As shown, the sidewall w1 can be non-perpendicular to the plane where the slot is located (i.e., β≠90°), for example, β=80°, 75° (i.e. α=10°, 15°).

[0088] Figure 8 The diagram shows the admittance curves of the resonator 100 when the tilt angle α of the sidewall w1 of the groove 103 is 0, 4°, 10°, 15°, 20°, 25°, 35°, and 45° (shifted by 10dB sequentially). It can be seen that when the tilt angle α is 0° (i.e., β = 90°), the admittance curve is smoothest between the resonant frequency (fr) and the anti-resonant frequency (fa). Furthermore, as the tilt angle α increases, the smoothness of the admittance curve between the resonant frequency (fr) and the anti-resonant frequency (fa) decreases. In other words, when the tilt angle α of the sidewall w1 of the groove 103 is 0° (i.e., β = 90°), the resonator has a better suppression effect on the transverse mode.

[0089] Furthermore, this application does not impose specific limitations on the depth of the groove 103; taking a solid-mounted resonator (SMR) as an example, refer to... Figure 7As shown, the groove 103 can penetrate part of the acoustic barrier layer in the reflective layer 102, that is, the depth of the groove 103 is less than the thickness of the reflective layer 102; of course, the groove 103 can also penetrate the entire reflective layer 102, that is, the depth of the groove 103 is equal to the thickness of the reflective layer 102; in practice, it can be set as needed.

[0090] It is understandable that the greater the depth of the groove 103, the less energy radiation leakage, which is more beneficial to improving the quality factor of the resonator. Therefore, in practice, the depth of the groove 103 can be increased as much as possible while meeting the normal requirements of the resonator (such as strength requirements).

[0091] Figure 9 The diagram shows the admittance curves (d1, d2, d3, d4; shifted by 10dB sequentially) of the resonator 100 with grooves 103 of different depths. Admittance curve d1 represents the groove 103 penetrating one acoustic resistive layer in the reflective layer 102; admittance curve d2 represents the groove 103 penetrating two acoustic resistive layers in the reflective layer 102; admittance curve d3 represents the groove 103 penetrating three acoustic resistive layers in the reflective layer 102; and admittance curve d4 represents the groove 103 penetrating all acoustic resistive layers in the reflective layer 102. It can be seen that when the groove 103 penetrates all acoustic resistive layers in the reflective layer 102, the admittance curve is smoothest between the resonant frequency (fr) and the anti-resonant frequency (fa). Furthermore, as the depth of the groove 103 decreases, the smoothness of the admittance curve between the resonant frequency (fr) and the anti-resonant frequency (fa) decreases. In other words, the greater the depth of the groove 103, the more transverse mode waves can be reflected, the less energy loss, and thus the better the suppression effect of transverse modes. This application does not impose a specific limit on the depth of the groove 103, which can be set as needed in practice.

[0092] In some possible implementations, the groove 103 may be filled with a low acoustic impedance material, which may include at least one of silicon oxide (SiO2) and silicon nitride (SiN); in some possible implementations, the groove 103 may also be filled with air; this application does not impose specific limitations on this, and it can be set as needed in practice.

[0093] Similarly, the outer side of the first side region A1 of the resonator 100 can also be air or filled with a low acoustic impedance material, such as at least one of silicon oxide (SiO2) and silicon nitride (SiN); this application does not impose any specific limitations on this.

[0094] As mentioned above, the resonator provided in this application embodiment can generate a broadband piston mode (BPM) at the flush boundary, thereby suppressing the generation of transverse modes over a wide frequency range. The following is a comparison and explanation of the admittance curves and Q-value curves of the TSBAR and SMR under the broadband piston mode (BPM) with the flush boundary provided in this application embodiment, and the TSBAR and SMR under the piston mode (PM) provided in the related art.

[0095] Figure 10 The admittance curve |Y| and conductance curve G of TSBAR under a flush boundary BPM provided in this application embodiment are as follows. Figure 11 This invention provides an admittance curve |Y| and conductance curve G of TSBAR under PM in the related technology, for comparison. Figure 10 and Figure 11 As shown, it can be seen that compared with the admittance curve |Y| of TSBAR under PM, the admittance curve |Y| of TSBAR provided in this application embodiment is smoother between the resonant frequency (fr) and the anti-resonant frequency (fa), that is, it has a better suppression effect on the transverse mode; in addition, compared with the conductance curve G of TSBAR under PM, the conductance curve G of TSBAR provided in this application embodiment has a lower base, that is, less loss.

[0096] Figure 12 This application provides an embodiment of the Q-value curve of TSBAR under a BPM with flush boundaries. Figure 13 This provides a Q-value curve for TSBAR under PM in the related technology; by Figure 12 It can be seen that the Q value of the TSBAR provided in the embodiments of this application is generally around 10. 3 The above is from Figure 13 It can be seen that the Q values ​​of TSBAR provided in related technologies are generally distributed around 10. 3 In other words, the TSBAR under BPM provided in the embodiments of this application can greatly improve the Q value, thereby improving the performance of the resonator.

[0097] Figure 14 This application provides an embodiment of the Q-value curve of SMR under BPM with flush boundaries. Figure 15 This provides a Q-value curve for SMR under PM in the related art; by Figure 14 As shown in the figure, the Q value of the SMR provided in the embodiments of this application is generally around 10. 3 The above is from Figure 15 It can be seen that the Q values ​​of SMR provided in related technologies are generally distributed around 10. 3In other words, the SMR under BPM provided in the embodiments of this application can greatly improve the Q value, thereby improving the performance of the resonator.

[0098] Furthermore, by comparing the admittance curve of SMR under BPM with flush boundaries provided in the embodiments of this application with the admittance curve of SMR under PM provided in the related art, it can also be found that, compared with the admittance curve of SMR under PM, the admittance curve of SMR provided in the embodiments of this application is smoother between the resonant frequency (fr) and the anti-resonant frequency (fa), that is, it has a better suppression effect on the transverse mode.

[0099] Regarding the groove 103 in this application, it should be understood that the opening edge (i.e. the edge opposite to the opening edge m1) and the sidewall (i.e. the sidewall opposite to the sidewall w1) of the groove 103 on the side away from the first side region A1 will hardly have an inhibitory effect on the transverse mode. Therefore, this application does not limit the specific setting of the opening edge and the sidewall of the groove 103 on the side away from the first side region A1.

[0100] In addition, for the resonator in this application embodiment, in practice, flush boundaries (i.e., some edges operate at BPM) can be set only at some edges of the resonator 100 to suppress transverse modes, while other related transverse mode suppression structures can be used for some edges.

[0101] Indicative, such as Figure 16 As shown, in some possible implementations, the first electrode a1 of the resonator 100 has a rectangular structure, comprising two sets of opposite sides (L1 and L2, L3 and L4). A first mass load P1 is provided at the first edge L1 of the first electrode a1, and a second mass load P2 is provided at the second edge L1. That is, by setting the first mass load P1 and the second mass load P2, a low-sound velocity region can be formed at the first edge L1 and the second edge L1 of the first electrode a1. The resonator 100 can adopt flush boundaries at the third edge L3 and the fourth edge L4 of the first electrode a1. In other words, the resonator 100 operates in piston mode (PM) at the first edge L1 and the second edge L1, and in broadband piston mode (BPM) at the third edge L3 and the fourth edge L4, in order to suppress transverse modes.

[0102] Indicative, such as Figure 17 As shown, in some possible implementations, the first electrode a1 of the resonator 100 adopts an irregular polygonal structure (i.e., the first electrode a1 is apodized), such as... Figure 17The first electrode a1 shown is a pentagonal structure with five sides (L1, L2, L3, L4, L5); through the irregular side structure, several strong transverse modes can be dispersed into countless weak transverse modes; the resonator 100 can adopt a flush boundary structure at one or more sides (such as L4, L5) of the first electrode a1 to suppress transverse modes through broadband piston mode (BPM).

[0103] The following is a schematic description of the method for manufacturing a resonator provided in the embodiments of this application. This method may include:

[0104] Step 01, Reference Figure 20 As shown in (c), a substrate S is provided, and a first metal film layer 14, a piezoelectric layer 13', and a second metal film layer 15 are sequentially formed on the substrate S.

[0105] Taking TSBAR as an example, step 01 above may include:

[0106] like Figure 18 As shown, for the above-mentioned substrate S, it may include forming a buffer layer 12 (such as a SiO2 layer) on a substrate 11 (such as a silicon substrate) to obtain the substrate S.

[0107] The formation of a first metal film layer 14, a piezoelectric layer 13', and a second metal film layer 15 sequentially disposed on the substrate S may include:

[0108] like Figure 19 As shown in (a) and (b), He+ ion implantation is performed on the piezoelectric wafer 13 (such as a lithium niobate wafer) to form a He+ implanted intermediate film H in the piezoelectric wafer 13; then, as shown in (a) and (b), Figure 19 As shown in (c), a first metal film layer 14 (such as an aluminum metal layer) is deposited on one side surface of the piezoelectric wafer 13; the first metal film layer 14 serves as the lower electrode of the transducer.

[0109] Next, as Figure 20 As shown in (a), the buffer layer 12 on the substrate 11 is bonded to the first metal film layer 14 on the piezoelectric wafer 13. Of course, the first metal film layer 14 can generally be surface treated before bonding.

[0110] Next, refer to Figure 20 As shown in (a) and (b), a heat treatment technique can be used to form He2 gas from the He+ ions injected into the piezoelectric wafer 13, thereby peeling off the piezoelectric wafer 13 along the intermediate film layer H where He+ was injected. In this case, the first metal film layer 14 and the piezoelectric layer 13' (i.e., piezoelectric thin film) located on the surface of the first metal film layer 14 are retained on the substrate S.

[0111] Next, for reference Figure 20 As shown in (c), a second metal film layer 15 (such as an aluminum metal layer) is formed on the surface of the piezoelectric layer 13'; the second metal film layer 15 serves as the upper electrode of the transducer.

[0112] Step 02, Reference Figure 21 As shown, the second metal film layer 15 is patterned, and the film layer located in at least a portion of the edge region of the second metal film layer 15 is removed to form an edge removal region E.

[0113] As illustrated, step 02 may include: Figure 21 As shown, the second metal film layer 15 formed in step 01 is patterned (which may include processes such as exposure, development, etching, and stripping) to form an edge removal region E in the edge region of the second metal film layer 15; the patterned second metal film layer 15 serves as the upper electrode of the transducer.

[0114] Step 03, Reference Figure 22 As shown in (a), a protective film 16 is formed on the surface of the patterned second metal film layer 15; Reference Figure 22 As shown in (b), a cutout w is formed on the protective film 16 at a position corresponding to the edge removal area E; wherein, the sidewall of the cutout w exposes the side of the second metal film layer 15 facing the edge removal area E.

[0115] Indicatively, step 03 may include: forming a protective film 16 on the surface of the patterned second metal film layer 15 using silicon dioxide; and patterning the protective film 16 (which may include processes such as exposure, development, etching, and stripping), forming a cutout w at the position of the corresponding edge removal area E.

[0116] Step 04, Reference Figure 22 As shown in (c), a groove 103 is formed at the location of the cutout w. In this case, the resonator has a flush boundary at the side wall of the groove 103.

[0117] Indicative, such as Figure 22 As shown in (c), step 04 above may include: etching the protective film 16, the second metal film layer 15, the piezoelectric layer 13', the first metal film layer 14, and the buffer layer 12 along the position of the cutout w to form a groove 103 based on inductively coupled plasma reactive ion etching (ICP RIE); wherein the protective film 16, the second metal film layer 15, the piezoelectric layer 13', the first metal film layer 14, and the buffer layer 12 form the edge portion of the sidewall of the groove 103 flush, that is, the resonator forms a flush boundary of the BPM structure on the sidewall of the groove 103 located on the edge of the second metal film layer 15.

[0118] Of course, for the creation of TSBAR, after step 04, it also includes: reference Figure 23 As shown, the cavity C is formed by etching the substrate 11 located below the buffer layer 12 at the location of the groove 17. For example, xenon difluoride (XeF2) can be used to etch the substrate 11 located below the buffer layer 12 at the location of the groove 17 to form the cavity C.

[0119] The above-described method for fabricating a resonator is illustrated using a TSBAR as an example, but this application is not limited to this. For an SMR, the fabrication method is similar to that of a TSBAR, with the main difference being the substrate S. For the fabrication of an SMR, the step of setting the substrate S may include: sequentially and alternately forming a high acoustic impedance layer and a low acoustic impedance layer to form a reflective layer on a substrate 11 (such as a silicon substrate). Other steps can be referred to the aforementioned embodiments and will not be repeated here.

[0120] For other related content in the above resonator fabrication method embodiments, please refer to the corresponding parts in the above resonator structure embodiments, which will not be repeated here; for the related structures in the above resonator structure embodiments, please refer to the above resonator fabrication method embodiments for fabrication, or make appropriate adjustments in combination with related technologies, which is not limited in this application.

[0121] Furthermore, this application does not limit the type of filter built using the resonator provided in any of the aforementioned possible implementation methods; for example, it can be a ladder-shaped filter.

[0122] As illustrated, this application provides a filter, such as Figure 24 As shown, the filter may include an input terminal IN, an output terminal OUT, a series branch B1, and at least one parallel branch B2. The series branch B1 is connected between the input terminal IN and the output terminal OUT. One end of the parallel branch B2 is connected to the series branch B1, and the other end is connected to ground. The series branch B1 contains at least two series resonators R1 connected in series, and the parallel branch B2 contains a parallel resonator R2.

[0123] In some embodiments, at least one (e.g., all) of the series resonators R1 in the series branches B1 described above may be configured to use the resonators provided in any of the possible implementations described above in this application.

[0124] In some embodiments, the parallel resonator R2 in at least one parallel branch B2 may be configured to use the resonator provided in any of the aforementioned possible implementations of this application.

[0125] In some embodiments, the series resonator R1 in the series branch B1 and the parallel resonator R2 in the parallel branch B2 may both be resonators provided in any of the aforementioned possible implementations of this application.

[0126] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A resonator characterized by, include: A substrate, a transducer disposed on the substrate, and a groove disposed on the substrate and located outside a first side region of the transducer; the transducer includes a first electrode, a piezoelectric layer, and a second electrode stacked together; the second electrode is close to the substrate relative to the first electrode. The first electrode includes a first edge, the piezoelectric layer includes a second edge, and the second electrode includes a third edge; The first edge is flush with the second edge, and the third edge is flush with the second edge; The flush portion of the edges of the first electrode, the piezoelectric layer, and the second electrode constitutes the first side region of the transducer. The opening edge of the groove on the side closest to the first side region of the transducer is flush with the edge of the second electrode.

2. The resonator according to claim 1, characterized in that, The angle between the sidewall of the groove on the side closest to the first side region of the transducer and the perpendicular line of the substrate is 0~25°.

3. The resonator of claim 1, wherein The sidewall of the groove near the first side region of the transducer is perpendicular to the substrate.

4. The resonator according to any one of claims 1-3, characterized in that The groove is a strip-shaped groove, and the strip-shaped groove extends along the first side region of the transducer.

5. The resonator according to any one of claims 1-3, characterized in that The groove is filled with at least one of silicon oxide and silicon nitride.

6. The resonator according to any one of claims 1-3, characterized in that The substrate has a cavity at the position corresponding to the transducer.

7. The resonator according to any one of claims 1-3, wherein The substrate includes a substrate and a reflective layer disposed on the substrate; The transducer is disposed on the surface of the reflective layer opposite to the substrate.

8. A filter, characterized by Including the resonator as described in any one of claims 1-7.

9. An electronic device, comprising: It includes a transceiver, a memory, and a processor; wherein the transceiver is provided with the filter as described in claim 8.

10. A method of fabricating a resonator, comprising: include: A substrate is provided, and a first metal film layer, a piezoelectric layer, and a second metal film layer are sequentially formed on the substrate. The substrate includes a substrate and a buffer layer. The second metal film layer is patterned, and the film layer located in at least a portion of the edge region of the second metal film layer is removed to form an edge removal region; A protective film is formed on the surface of the patterned second metal film layer, and a cutout is formed on the protective film at a position corresponding to the edge removal area; wherein, the sidewall of the cutout exposes the side of the second metal film layer facing the edge removal area; Along the location of the cutout, the protective film, the second metal film, the piezoelectric layer, the first metal film, and the buffer layer are etched to form a groove at the location of the cutout, wherein the edge portions of the protective film, the second metal film, the piezoelectric layer, the first metal film, and the buffer layer forming the sidewalls of the groove are flush.

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