Acoustic resonator structure and its acoustic devices

Abstract

This invention provides an acoustic resonator structure and its acoustic device. By altering the stacking structure of the acoustic resonator in the thickness direction to create a deceleration region within the supporting substrate and / or dielectric layer, the velocity profile curve of the target acoustic wave in the aperture direction of the acoustic resonator can be controlled. This changes the propagation conditions of higher-order transverse spurious modes at the end boundary of the aperture region, reducing their energy integral, effectively suppressing and eliminating spurious responses, reducing insertion loss and clutter interference in the passband, and achieving a flat filter passband. The acoustic resonator and acoustic device provided by this invention have a simple structure, requiring only preprocessing of the supporting substrate and / or dielectric layer. There is no need to damage the integrity of the piezoelectric layer or deform the interdigitated electrodes, thus providing a simple and effective design solution for suppressing higher-order transverse spurious modes.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology and relates to an acoustic resonator structure and its acoustic device. Background Technology

[0002] To meet the demands for miniaturization and low cost in RF mobile terminals, acoustic wave devices, with their small size, simple manufacturing process, and high performance, have demonstrated significant advantages. However, the problem of spurious acoustic mode excitation remains to be solved. For example, during target mode excitation, unnecessary multi-order transverse spurious modes are generated between the resonant frequency and anti-resonant frequency of the target mode. As a result, multiple spurious resonance peaks will be distributed in the device response, corresponding to ripple in the passband of the filter device. This leads to increased insertion loss and poor passband edge steepness, which seriously affects the accuracy and stability of signal transmission and reception.

[0003] Existing technologies propose designing variations for patterned interdigital electrodes, such as apodization electrodes, which adjust the lateral resonant cavity length of each interdigital electrode to eliminate higher-order stray resonance peaks. However, this approach also deteriorates the resonant performance of the target mode, leading to a decrease in the device quality factor. Another approach is to adjust the duty cycle or mass loading of different regions of the interdigital electrode to adjust the velocity profile curve and suppress higher-order stray modes. However, this approach increases the precision requirements of the electrode linewidth, thereby increasing the difficulty and cost of manufacturing.

[0004] Therefore, it is necessary to provide an acoustic resonator structure and its acoustic device. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an acoustic resonator structure and acoustic device thereof to solve the problem of transverse spurious modes appearing in the response of acoustic devices in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides an acoustic resonator structure, the acoustic resonator structure comprising:

[0007] Support substrate;

[0008] A piezoelectric layer, the piezoelectric layer being located on the upper surface of the supporting substrate;

[0009] A patterned electrode is located on the upper surface of the piezoelectric layer. The patterned electrode includes a central interdigitated region and reflective grating regions located on both sides of the central interdigitated region in the direction of acoustic wave propagation. In the aperture direction, the central interdigitated region includes a first busbar region, a first air gap region, an aperture region, a second air gap region, and a second busbar region.

[0010] The deceleration region extends downward from the upper surface of the supporting substrate along the thickness direction and includes at least the region directly below one or a combination of the aperture region and the air gap region. The deceleration region is symmetrically distributed in the aperture direction and reduces the target acoustic velocity of the piezoelectric layer in the corresponding region through the deceleration region.

[0011] Optionally, the deceleration zone also includes the region located directly below the busbar zone.

[0012] Optionally, along the thickness direction, the thickness of the deceleration zone located directly below different regions may be the same or different.

[0013] Optionally, in the direction of sound wave propagation, with one interdigitated period as the unit 1, the duty cycle of the deceleration zone is 0.5 to 1; in the direction of sound wave propagation, the deceleration zone is centrally symmetrical within one interdigitated period.

[0014] Optionally, it further includes a dielectric layer located between the supporting substrate and the piezoelectric layer, and the deceleration region is located in the dielectric layer and / or the supporting substrate in the thickness direction. When the dielectric layer is provided with the deceleration region, the deceleration region is opened from the bottom surface of the dielectric layer upward, and the ratio of the groove depth of the deceleration region to the thickness of the dielectric layer is 0.1 to 1.

[0015] Optionally, a piezoelectric single-crystal substrate is provided to replace the stacked support substrate and the piezoelectric layer, and the piezoelectric single-crystal substrate and the piezoelectric layer have the same material.

[0016] Optionally, the preset depth of the deceleration zone is less than 1 μm, and the thickness of the deceleration zone is greater than 50 nm.

[0017] Optionally, it may also include a first additional finger located in the first air gap region and a second additional finger located in the second air gap region, wherein the first additional finger is electrically connected to the first busbar and the second additional finger is electrically connected to the second busbar.

[0018] Optionally, the deceleration zone may include a preset groove opened in the target area, or be formed by filling the preset groove with a low-velocity material, or be formed by ion implantation in the target area.

[0019] The present invention also provides an acoustic wave device, the acoustic wave device comprising any of the above-mentioned acoustic wave resonator structures; the acoustic wave device comprising at least one of a filter, a duplexer, and a multiplexer.

[0020] As described above, the acoustic resonator structure and its acoustic device of the present invention, by changing the stacking structure of the acoustic resonator in the thickness direction to provide a deceleration region in the supporting substrate layer and / or dielectric layer, can regulate the velocity profile curve of the target acoustic wave in the aperture direction of the acoustic resonator, change the propagation conditions of the higher-order transverse spurious modes at the end boundary of the aperture region, reduce their energy integral, effectively suppress and eliminate spurious response, reduce the insertion loss and clutter interference in the passband, and achieve a flat filter passband.

[0021] The acoustic resonator and acoustic device provided by this invention have a simple structure. Only the supporting substrate and / or dielectric layer need to be pre-processed. There is no need to destroy or damage the integrity of the piezoelectric layer, nor is there any need to deform the interdigitated electrodes. Therefore, it is a simple and effective design scheme for suppressing high-order lateral stray modes. Attached Figure Description

[0022] Figure 1 The diagram shown is a top view of the acoustic resonator structure provided by the present invention.

[0023] Figure 2 The diagram shows the position of the preset slot in the acoustic resonator structure provided by the present invention.

[0024] Figure 3 The diagram shows a periodic model and a unit periodic model of the acoustic resonator structure provided by the present invention in the second direction.

[0025] Figure 4 The diagram shown is a top view of the acoustic resonator structure provided by the present invention.

[0026] Figure 5 The diagram shows a comparison of the simulated admittance curves of the horizontal shear waves excited in the structures of Comparative Example 1, Example 1, Example 2 and Example 3 of this invention.

[0027] Figure 6 The diagram shows a comparison of the simulated admittance curves of the structures excited with horizontal shear waves in Comparative Examples 1, 2, 4 and 5 of this invention.

[0028] Figure 7 The diagram shows a comparison of the simulated admittance curves of the horizontal shear waves excited in the structures of Comparative Examples 1, 6, and 7 of this invention.

[0029] Figure 8 The diagram shown is a top view of the acoustic resonator structure provided in Comparative Example 2 and Example 7 of the present invention.

[0030] Figure 9 Displayed as Figure 8 Schematic diagram of the cross-sectional structure along the middle A-A' and A”-A”' and the corresponding velocity profile curve.

[0031] Figure 10 The diagram shows a comparison of the simulated admittance curves of the structures excited with horizontal shear waves in Comparative Examples 2, 8, 9 and 10 of this invention.

[0032] Figure 11 The diagram shows a comparison of the simulated admittance curves of the structures excited with horizontal shear waves in Comparative Examples 3, 11, 12 and 13 of this invention.

[0033] Explanation of reference numerals in the attached figures

[0034] 100 Supporting substrate

[0035] 200 piezoelectric layer

[0036] 110 piezoelectric single crystal substrate

[0037] 300 patterned electrodes

[0038] 400 deceleration zone

[0039] 401 First Deceleration Zone

[0040] 402 Second Deceleration Zone

[0041] 500 dielectric layer

[0042] 601 First Additional Instruction

[0043] 602 Second Additional Indication Detailed Implementation

[0044] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0045] In the detailed description of embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0046] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include orientations of the device in use or operation other than those depicted in the drawings, and may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact. Furthermore, when a layer is referred to as “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0047] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0048] See Figures 1-4 This application provides an acoustic resonator structure, comprising: a supporting substrate 100, a piezoelectric layer 200, a patterned electrode 300, and a deceleration region 400. The piezoelectric layer 200 is located on the upper surface of the supporting substrate 100; the patterned electrode 300 is located on the upper surface of the piezoelectric layer 200. The patterned electrode 300 includes a central interdigitated region and reflective grating regions located on both sides of the central interdigitated region in the acoustic wave propagation direction (defined as a first direction), and the central interdigitated region includes... The system includes a first busbar region, a first air gap region, an aperture region, a second air gap region, and a second busbar region. The first busbar and the second busbar are electrically connected to an electrical signal and a ground signal, respectively. The deceleration region 400 extends downward from the upper surface of the supporting substrate along the thickness direction (defined as the third direction) and includes at least the region directly below one or a combination of the aperture region and the air gap region. The deceleration region 400 is symmetrically distributed in the aperture direction, and the deceleration region 400 reduces the target acoustic velocity of the piezoelectric layer 200 in the corresponding region.

[0049] Specifically, the setting of the deceleration region 400 includes introducing a low sound velocity transition region at the end of the aperture region that is lower than the sound velocity in the aperture region, or reducing the sound velocity difference between the aperture region and the void region, so that the target sound velocity of the piezoelectric layer 200 corresponding to the deceleration region 400 is lower than the target sound velocity of the piezoelectric layer 200 originally corresponding to that region. Thus, the velocity profile curve of the target sound wave in the aperture direction can be adjusted by the deceleration region 400, changing the propagation conditions of the higher-order transverse spurious mode at the end boundary of the aperture region, reducing its energy integral, effectively suppressing and eliminating spurious response, reducing the insertion loss and clutter interference in the passband, and achieving a flat filter passband.

[0050] The deceleration zone 400 is provided in the material region corresponding to at least the end of the aperture region and / or directly below the air gap region. The setting of the deceleration zone 400 is actually to adjust the velocity profile curve to change the vibration level of the higher-order stray sound wave at the boundary and the energy integral in the second direction.

[0051] In the first direction: taking one interdigital cycle as a unit 1, the duty cycle of the deceleration zone 400 is 0.5 to 1, and preferably, within one interdigital cycle in the direction of sound wave propagation, the deceleration zone 400 is centrally symmetrical; in the second direction: the deceleration zone 400 can be located in the aperture end region, or the air gap region, or the aperture end region + air gap region, or the air gap region + busbar region, or the aperture end region + busbar region, or the aperture end region + air gap region + busbar region, that is, it is necessary to satisfy the requirement that the aperture end region and / or the air gap region have low sound velocity in the deceleration zone 400. 00, and the deceleration region 400 is symmetrically distributed in the second direction, that is, when the first air gap region is provided with the first deceleration region 401, the corresponding second air gap region is also provided with the second deceleration region 402 symmetrically distributed in the second direction; in the third direction: the deceleration region 400 is located in the region where the support substrate extends downward along the upper surface, that is, the setting of the deceleration region 400 does not damage the piezoelectric layer 200, wherein, when the deceleration region 400 includes two or more regions, the thickness of the deceleration region 400 corresponding to the material region directly below the different regions can be the same or different.

[0052] As an example, it may also include a dielectric layer 500 located between the support substrate 100 and the piezoelectric layer 200, and the deceleration region 400 is included in the dielectric layer 500 and / or the support substrate in the thickness direction, and when the dielectric layer 500 is provided with the deceleration region 400, the deceleration region 400 is opened upward on the bottom surface of the dielectric layer 500, and the ratio of the groove depth of the deceleration region 400 to the thickness of the dielectric layer 500 is 0.1 to 1.

[0053] Specifically, such as Figure 2(a) The dielectric layer 500 may be disposed between the supporting substrate 100 and the piezoelectric layer 200, and the deceleration region 400 may be disposed in the dielectric layer 500. The deceleration region 400 disposed in the dielectric layer 500 is opened from the bottom surface of the dielectric layer 500 upward, and the ratio of the groove depth to the thickness of the dielectric layer 500 is 0.1 to 1.

[0054] As an example, a piezoelectric single crystal substrate 110 is provided to replace the stacked support substrate 100 and the piezoelectric layer 200, and the piezoelectric single crystal substrate 110 and the piezoelectric layer 200 have the same material.

[0055] Specifically, such as Figure 2 (b) A schematic cross-sectional view of the acoustic resonator structure based on the supporting substrate 100 and the piezoelectric layer 200. Figure 2 (c) shows a cross-sectional view of the acoustic resonator structure based on the piezoelectric single crystal substrate 110.

[0056] When using the piezoelectric single crystal substrate 110, the preset depth of the deceleration region 400 is less than 1 μm, that is, the distance between the upper surface of the deceleration region 400 and the upper surface of the piezoelectric single crystal substrate 110 does not exceed 1 μm, and the thickness of the deceleration region 400 is greater than 50 nm.

[0057] As an example, it also includes a first additional finger 601 located in the first air gap region and a second additional finger 602 located in the second air gap region, wherein the first additional finger 601 is electrically connected to the first busbar and the second additional finger 602 is electrically connected to the second busbar.

[0058] Specifically, such as Figure 1 (f) shows a top view of the acoustic resonator structure with additional fingers. The deceleration region 400 may or may not exist in the target region directly below the regions of the first additional finger 601 and the second additional finger 602, depending on the specific requirements.

[0059] As an example, the deceleration zone 400 may include a preset groove opened in the target area, or be composed of a low-velocity material filled in the preset groove, or be composed of ion implantation in the target area.

[0060] Specifically, the method for implementing the deceleration zone 400 may include, but is not limited to, opening a preset groove in the target area, or performing ion implantation in the target area.

[0061] When the scheme of opening a preset groove is selected, the groove can be left empty after opening, or a low-velocity material can be filled into the preset groove so that the slow shear wave velocity in the deceleration zone is lower than the target mode velocity of the piezoelectric layer 200.

[0062] When using the pre-defined groove method, bonding of the support substrate 100 to the dielectric layer 500 or the piezoelectric layer 200 can be performed after creating windows in the corresponding target areas of the support substrate 100 and / or the dielectric layer 500. The presence of these periodically arranged, small-sized windows also introduces an excellent effect of releasing bonding stress. These windows can be formed using methods such as etching, etching, local ion implantation followed by etching and / or etching, and annealing after local ion implantation.

[0063] When using a local ion implantation scheme: you can choose simple local ion implantation to modify the material at that location into a low-velocity material region, or you can choose a scheme of local ion implantation followed by annealing to obtain a low-velocity material region.

[0064] When forming the patterned electrode 300 located on the surface, for heterostructures, the alignment method of the deceleration region 400 may include:

[0065] The support substrate 100 is provided, and the deceleration region 400 is fabricated at a specific target location. Alignment marks are provided on the support substrate 100 so that each subsequent layer can locate the position of the deceleration region 400 via these alignment marks, thereby aligning and fabricating the patterned electrode 300 on the surface. When the dielectric layer 500 is present, it can be formed first on the surface of the support substrate 100. If the deceleration region 400 is disposed within the dielectric layer 500, or if both the support substrate 100 and the dielectric layer 500 contain the deceleration region 400, then alignment marks need to be provided on the support substrate 100, and these alignment marks should be continued on the dielectric layer 500.

[0066] The piezoelectric layer 200 is formed on the surface of the support substrate 100 or the dielectric layer 500, and alignment marks are continued thereafter.

[0067] The patterned electrode 300 is fabricated on the piezoelectric layer 200 by referring to the alignment marks.

[0068] When forming the patterned electrode 300 located on the surface, for non-heterogeneous structures, i.e., for the piezoelectric single-crystal substrate 110, the alignment method of the deceleration region 400 may include:

[0069] The piezoelectric single crystal substrate 110 is provided, and the deceleration region 400 is prepared at a specific target region location. Alignment marks are set on the piezoelectric single crystal substrate 110 so that each subsequent layer can locate the position of the deceleration region 400 through the alignment marks, so as to align and realize the preparation of the patterned electrode 300 on the surface.

[0070] The patterned electrode 300 is fabricated on the piezoelectric layer 200 by referring to the alignment marks.

[0071] The methods for forming the dielectric layer 500 on the support substrate 100 include, but are not limited to, bond stripping, physical vapor deposition, chemical vapor deposition, magnetron sputtering, and thermal oxidation deposition.

[0072] Methods for forming the piezoelectric layer 200 on the support substrate 100 or the dielectric layer 500 include, but are not limited to, ion implantation of a piezoelectric single crystal followed by bonding and peeling with the support substrate 100 or the dielectric layer 500 to transfer the piezoelectric layer 200 to the upper surface of the support substrate 100 or the dielectric layer 500; or bonding the piezoelectric single crystal with the support substrate 100 or the dielectric layer 500 and then grinding and polishing it to the target thickness; or deposition using physical vapor deposition, chemical vapor deposition, magnetron sputtering, or Czochralski crystal growth.

[0073] The methods for forming the patterned electrode 300 include, but are not limited to, electron beam evaporation, thermal evaporation, magnetron sputtering, etc.

[0074] This application also provides an acoustic wave device, which includes any of the above-mentioned acoustic wave resonator structures. The acoustic wave device may include at least one of filters, duplexers, and multiplexers, and the specific types are not limited here.

[0075] The acoustic resonator structure described in this application will be further described below with reference to comparative examples and specific examples.

[0076] Comparative Example 1: Sapphire was used as the heterostructure substrate, silicon oxide (SiO2) was used as the dielectric layer with a thickness of 400 nm, lithium tantalate (LiTaO3) piezoelectric film with a thickness of 360 nm was used as the piezoelectric layer with a YX 42° rotation, and aluminum (Al) was used as the interdigitated electrode with an interdigital period of 1.2 μm, an electrode thickness of 80 nm, and a duty cycle of 0.5; the target acoustic wave mode to be excited was the horizontal shear wave (SH-SAW) mode.

[0077] The schematic diagram of the second direction model, which includes one interdigital cycle, is shown below. Figure 3 As shown in (a), the element model of the air gap region is as follows: Figure 3As shown in (b), the cross-sectional schematic diagram of the resonator structure is as follows. Figure 2 As shown in (a), a top view of the device's surface is shown in [reference needed]. Figure 4 (a).

[0078] Example: Using Sapphire as the supporting substrate and SiO2 as the dielectric layer, the SiO2 layer thickness in the ungrooved, intact region is 400 nm, wherein there are pre-defined grooves on the surface of Sapphire and / or the bottom surface of the SiO2 layer; a LiTaO3 piezoelectric film is rotated YX 42° to form a piezoelectric layer with a thickness of 360 nm; metal Al interdigitates are used as interdigitated electrodes with an interdigitate period of 1.2 μm, an electrode thickness of 80 nm, and a duty cycle of 0.5; a horizontal shear wave SH-SAW mode is excited and generated.

[0079] Similarly, the resonator structure includes a second-direction model diagram with an interdigitated period, as shown in the figure below. Figure 3 As shown in (a), the preset groove is located directly below the air gap region, in the material region other than the LiTaO3 piezoelectric layer, including the Sapphire region and the SiO2 region.

[0080] Examples 1-3: The preset trenches are only formed in the SiO2 layer, corresponding to the removal of 80nm, 150nm, and 400nm of SiO2 from the bottom surface of the SiO2 layer in contact with the Sapphire layer towards the top surface, respectively. The element models of the air gap region correspond to... Figure 3 (c) and Figure 3 (d) A top view of the surface of the pre-set groove is shown in [reference]. Figure 4 (b)

[0081] Example 4: The pre-defined trench is only made on the Sapphire substrate. A 150nm Sapphire trench is removed downwards from the upper surface where the Sapphire contacts the SiO2 layer. The cell model of the air gap region is as follows. Figure 3 As shown in (e), a top view of the surface of the preset groove is provided. Figure 4 (b)

[0082] Example 5: Preset trenches are simultaneously formed within both the SiO2 layer and the Sapphire layer, with a trench depth of 150 nm in both layers. The unit cell model of the air gap region is as follows: Figure 3 As shown in (e), a top view of the surface of the preset groove is provided. Figure 4 (b)

[0083] Example 6: Expanding the slotted area, the pre-set slots are located in the SiO2 layer directly below the interdigitated ends of the aperture region, the air gap, and part of the busbar region. The slot depth is 250nm. See the top view diagram of the pre-set slot surface. Figure 4 (c)

[0084] Example 7: Based on the case of Example 6, the preset trench is formed in the SiO2 layer directly below the interdigitated ends of the aperture region, the air gap, and part of the busbar region. The trench depth corresponding to the interdigitated ends of the aperture region and the air gap is 250 nm, and the trench depth corresponding to the part of the busbar region is 150 nm. A top view of the surface of the preset trench is shown below. Figure 4 (c)

[0085] Simulations were performed on the acoustic resonators with the structures of Comparative Example 1 and Examples 1 to 7. The comparison curves between Comparative Example 1 and Examples 1 to 3 were plotted on... Figure 5 The comparison curves for Example 1, Example 2, Example 4, and Example 5 are plotted on... Figure 6 The comparison curves between Example 1 and Examples 6 and 7 are plotted on... Figure 7 .

[0086] Depend on Figure 5 As can be seen, compared with the resonator based on the traditional structure in Comparative Example 1, the resonators in Examples 1 to 3 all exhibit smoother admittance response curves, reflecting the effective suppression effect of introducing a low-velocity region in the dielectric layer on transverse clutter. It also shows that the preset thickness of the deceleration region affects the clutter suppression effect; therefore, the clutter suppression level can be optimized and improved by designing the preset thickness of the deceleration region.

[0087] Depend on Figure 6 As can be seen, compared to Comparative Example 1, which is based on a traditional resonator structure, the resonators in Examples 2, 4, and 5 also exhibit smoother admittance response curves, reflecting the effective suppression of transverse clutter by introducing a low-velocity region in the supporting substrate and dielectric layer. This indicates that the clutter suppression effect can be further improved by designing the orientation and size of the deceleration region.

[0088] Depend on Figure 7 As can be seen, compared with the resonator based on the traditional structure in Comparative Example 1, the resonators in Examples 6 and 7 exhibit very smooth admittance response curves, reflecting a significant transverse clutter cancellation effect.

[0089] Comparing Examples 1 to 5 shows that different orientations and sizes of the deceleration zone have a significant impact on clutter suppression. It also reflects that adjusting the boundary conditions and energy integrals of the velocity profile curve and higher-order transverse clutter modes can effectively control the excitation and suppression of transverse clutter.

[0090] Figure 8 The surface interdigitated electrode design and the location of the preset groove, i.e. the deceleration zone, shown in Comparative Example 1 and Example 7 are illustrated.

[0091] Figure 9 Then corresponding Figure 8The velocity profile curves of the target sound wave under the given cross-sectional structure are plotted for two different designs. Here, the sound velocity is calculated using the period as the unit. It can be seen that in Example 7 of this invention, by opening a preset slot, a low-velocity reduction zone is introduced in the interdigital end region of the aperture area, changing the sound wave reflection conditions at the boundary. This changes the energy integral of the higher-order transverse clutter, significantly reducing it or making it zero, thus suppressing and eliminating transverse clutter.

[0092] Comparative Example 2: Using silicon carbide (SiC) as the heterogeneous support substrate, a LiTaO3 piezoelectric thin film, rotated YX 42°, was used as the piezoelectric layer with a thickness of 360 nm; metallic Al was used as the interdigitated electrode with an interdigitation period of 1.2 μm, an electrode thickness of 80 nm, and a duty cycle of 0.5; the target acoustic wave mode to be excited was the SH-SAW mode. A schematic cross-sectional view of the resonator structure is shown below. Figure 1 As shown in (b), the top view of the device surface is as follows: Figure 4 (a).

[0093] Examples 8 and 9: A SiC layer is used as the supporting substrate, and a LiTaO3 piezoelectric film is used as the piezoelectric layer with a thickness of 360 nm; metallic Al is used as the interdigitated electrode with an interdigitated period of 1.2 μm, an electrode thickness of 80 nm, and a duty cycle of 0.5; a horizontal shear wave SH-SAW mode is generated.

[0094] The preset trench is only opened in the SiC layer. Taking a 250nm reduction from the upper surface of the LiTaO3-SiC layer contact point downwards towards the bottom surface, the unit cell models for the air gap region correspond to... Figure 3 (c) and Figure 3 (d); Examples 8 and 9 correspond to the cases of not filling and filling with SiO2 after opening the preset slot, respectively.

[0095] Example 10: Based on the structure of Example 9, the interdigitated electrode has a first additional finger and a second additional finger. A top view of the device surface is shown below. Figure 4 (d)

[0096] The simulation admittance comparison curves of Comparative Example 2 and Examples 8 to 10 are plotted on Figure 10 .

[0097] Depend on Figure 10 It can be seen that in the LiTaO3-SiC structure, setting a low-velocity region on the surface of the supporting substrate also has a significant suppression effect on transverse stray modes. By adjusting the orientation and size of the deceleration region, the boundary conditions and energy integrals of the velocity profile curve and higher-order transverse clutter modes can be effectively controlled, thus effectively controlling the excitation and suppression of transverse clutter.

[0098] Comparative Example 3: LiTaO3 piezoelectric single crystal was used as the supporting substrate and piezoelectric layer; metallic Al was used as the interdigitated electrode with an interdigitation period of 1.2 μm, an electrode thickness of 80 nm, and a duty cycle of 0.5; a horizontal shear wave SH-SAW mode was generated. A schematic cross-sectional view of the resonator structure is shown below. Figure 2 As shown in (c), the top view of the device surface is as follows: Figure 4 (a).

[0099] Examples 11, 12, and 13: Using LiTaO3 piezoelectric single crystal as the supporting substrate and piezoelectric layer; using metallic Al as interdigitated electrodes with an interdigitated period of 1.2 μm, an electrode thickness of 80 nm, and a duty cycle of 0.5; generating horizontal shear wave SH-SAW mode.

[0100] See the top view of the surface in Example 11. Figure 4 (b) The pre-set groove is opened in the piezoelectric layer directly below the air gap region, at a height of 360 nm from the upper surface, and the groove depth is 250 nm. After the groove is opened, low-velocity SiO2 material is filled in the groove.

[0101] See the top view of the surface in Example 12. Figure 4 (c) The pre-set groove is opened in the piezoelectric layer located directly below the interdigital ends of the aperture region, the air gap and part of the busbar region, with a height of 360 nm from the upper surface and a groove depth of 250 nm. After the groove is opened, a low-velocity SiO2 layer is filled in the groove.

[0102] The slot in Example 13 is in the same location as in Example 2, and no other material is filled after the slot is made.

[0103] Simulations were performed on the acoustic resonators under the structures of Comparative Example 3 and Examples 11 to 13 above, and the admittance response comparison curves were plotted on... Figure 11 .

[0104] Depend on Figure 11 It can be seen that setting a low-velocity region in the piezoelectric single-crystal substrate is also effective in suppressing lateral stray modes, demonstrating the versatility of this approach. By adjusting the orientation and size design of the deceleration region, and controlling the boundary conditions and energy integrals of the velocity profile curve and higher-order lateral clutter modes, the excitation and suppression of lateral clutter can be effectively controlled.

[0105] In summary, the acoustic resonator structure and its acoustic device of the present invention, by changing the stacking structure of the acoustic resonator in the thickness direction to set a deceleration region in the supporting substrate layer and / or dielectric layer, can control the velocity profile curve of the target acoustic wave in the aperture direction of the acoustic resonator, change the propagation conditions of the higher-order transverse spurious modes at the end boundary of the aperture region, reduce their energy integral, effectively suppress and eliminate spurious response, reduce the insertion loss and clutter interference in the passband, and achieve a flat filter passband.

[0106] The acoustic resonator and acoustic device provided by this invention have a simple structure. Only the supporting substrate and / or dielectric layer need to be pre-processed. There is no need to destroy or damage the integrity of the piezoelectric layer, nor is there any need to deform the interdigitated electrodes. Therefore, it is a simple and effective design scheme for suppressing high-order lateral stray modes.

[0107] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An acoustic resonator structure, characterized in that, The acoustic resonator structure includes: Support substrate; A piezoelectric layer, the piezoelectric layer being located on the upper surface of the supporting substrate; A patterned electrode is located on the upper surface of the piezoelectric layer. The patterned electrode includes a central interdigitated region and reflective grating regions located on both sides of the central interdigitated region in the direction of acoustic wave propagation. In the aperture direction, the central interdigitated region includes a first busbar region, a first air gap region, an aperture region, a second air gap region, and a second busbar region. A deceleration region extends downward from the upper surface of the supporting substrate along the thickness direction, and includes at least the region directly below one or a combination of the aperture region and the air gap region. The deceleration region is symmetrically distributed in the aperture direction. It reduces the target acoustic wave velocity of the piezoelectric layer in the corresponding region, thereby controlling the velocity profile curve of the target acoustic wave in the aperture direction of the acoustic resonator. This alters the propagation conditions of higher-order lateral stray modes at the aperture region's end boundary, reducing their energy integral and effectively suppressing and eliminating stray responses. In the acoustic wave propagation direction, with one interdigital period as the unit, the duty cycle of the deceleration region is 0.5~1. Within one interdigital period in the acoustic wave propagation direction, the deceleration region is centrally symmetrical. The preset depth of the deceleration region is less than 1 µm, and the thickness of the deceleration region is greater than 50 nm.

2. The acoustic resonator structure according to claim 1, characterized in that: The deceleration zone also includes the area located directly below the busbar zone.

3. The acoustic resonator structure according to claim 1, characterized in that: Along the thickness direction, the thickness of the deceleration zone located directly below different regions may be the same or different.

4. The acoustic resonator structure according to claim 1, characterized in that: It also includes a dielectric layer located between the supporting substrate and the piezoelectric layer, and the deceleration region is located in the dielectric layer and / or the supporting substrate in the thickness direction. When the dielectric layer is provided with the deceleration region, the deceleration region is opened from the bottom surface of the dielectric layer upward, and the ratio of the groove depth of the deceleration region to the thickness of the dielectric layer is 0.1 to 1.

5. The acoustic resonator structure according to claim 1, characterized in that: A piezoelectric single-crystal substrate is provided to replace the stacked support substrate and the piezoelectric layer, and the piezoelectric single-crystal substrate and the piezoelectric layer have the same material.

6. The acoustic resonator structure according to claim 1, characterized in that: It also includes a first additional finger located in the first air gap region and a second additional finger located in the second air gap region, wherein the first additional finger is electrically connected to the first busbar and the second additional finger is electrically connected to the second busbar.

7. The acoustic resonator structure according to claim 1, characterized in that: The deceleration zone includes a preset groove opened in the target area, or is formed by filling the preset groove with a low-velocity material, or is formed by ion implantation in the target area.

8. An acoustic wave device, characterized in that, The acoustic device includes the acoustic resonator structure as described in any one of claims 1-7; the acoustic device includes at least one of a filter, a duplexer, and a multiplexer.

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