Surface acoustic wave device with transverse modal suppression effect

Abstract

The invention provides a surface acoustic wave device with a transverse mode suppression effect, the device comprises a substrate and an IDT electrode, the IDT electrode comprises two interdigital electrodes which are oppositely arranged, each interdigital electrode comprises a bus bar, a plurality of electrode fingers and a plurality of false finger groups, and each false finger group at least comprises two false fingers which are arranged at intervals. The electrode fingers of different interdigital electrodes are arranged at intervals in a staggered mode, the false finger sets and the electrode fingers of the same interdigital electrode are arranged at intervals in an alternating mode, and the tail end of each electrode finger is opposite to the tail end of one false finger set and keeps a gap with the tail end of the false finger set. According to the acoustic surface wave device, the propagation speed of the acoustic surface wave in the corresponding range of the false fingers is changed by utilizing the setting positions, the setting number and the connection relation between the different false fingers in the false finger group and the connection relation between the false fingers and the electrode fingers, so that the effects of inhibiting transverse mode resonance and improving the Q value of the acoustic surface wave device are achieved.

Description

Technical Field

[0001] The present application relates to the field of surface acoustic wave technology, and in particular to a surface acoustic wave device with a transverse mode suppression effect. Background Art

[0002] The basic structure of the surface acoustic wave (SAW) device is to make an acoustic-electric transducer on a piezoelectric substrate material. It has the advantages of small size, large bandwidth, low insertion loss, low cost, and mass production, and is widely used in mobile communication devices. With the development of communication protocols, the requirements for RF devices such as filters and duplexers are getting higher and higher. The optimized design of the acoustic-electric transducer is particularly important for obtaining high-performance SAW devices.

[0003] In recent years, surface acoustic wave devices have been widely used due to their excellent quality factor (Q value), low temperature drift coefficient, large bandwidth, high power, etc. However, existing surface acoustic wave devices will be excited during use and produce unnecessary transverse modal spurious (or transverse resonant mode, transverse mode, etc.). The spurious response generated by these transverse modes will cause fluctuations in the passband, increase the energy loss of the surface acoustic wave device, reduce the Q value of the surface acoustic wave device, and affect the performance.

[0004] Therefore, how to provide a surface acoustic wave device with a transverse mode suppression effect, which can suppress the influence of the transverse mode on the performance of the surface acoustic wave device and improve the Q value, has become one of the technical problems that people in this field need to solve urgently. Summary of the invention

[0005] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0006] To this end, the first purpose of the present application is to propose a surface acoustic wave device with a lateral mode suppression effect, which can suppress the influence of the lateral mode on the device performance, reduce the influence of the lateral mode on the Q value of the device, and improve the device performance.

[0007] To achieve the above-mentioned purpose, the first embodiment of the present application proposes a surface acoustic wave device with a transverse mode suppression effect, comprising:

[0008] substrate;

[0009] The IDT electrode comprises two interdigitated electrodes arranged opposite to each other on the substrate; each of the interdigitated electrodes comprises a bus bar extending along a first direction, and a plurality of electrode fingers and a dummy finger group extending from one side of the bus bar along a second direction, each of the dummy finger groups comprises at least two dummy fingers spaced apart in the first direction, the second direction is orthogonal to the first direction, and the orthogonal plane is parallel to the surface of the substrate;

[0010] Among them, in the first direction, the electrode fingers of different interdigitated electrodes are arranged in an alternating manner, and the pseudo-finger group and the electrode fingers of the same interdigitated electrode are arranged in an alternating manner; in the second direction, the end of an electrode finger and the end of a pseudo-finger group are spaced apart from each other and correspond one to one.

[0011] Optionally, the pseudo finger group includes at least a first pseudo finger and a second pseudo finger, and the center axes of the first pseudo finger and the second pseudo finger along the second direction are respectively at the same distance from the center axes of the corresponding electrode fingers along the second direction.

[0012] Optionally, the first pseudo finger and the second pseudo finger have different extension lengths in the second direction.

[0013] Optionally, the first pseudo finger and the second pseudo finger are symmetrical to each other with the central axis of the corresponding electrode finger in the second direction as the axis. Optionally, the maximum gap distance between the first pseudo finger and the second pseudo finger in the first direction is equal to the difference between the gap distance between two adjacent electrode fingers of the same interdigitated electrode and the width of the first pseudo finger and the second pseudo finger.

[0014] Optionally, the pseudo finger group further includes a first connecting portion, which is located in a gap between the first pseudo finger and the second pseudo finger and extends along the first direction to connect the first pseudo finger and the second pseudo finger.

[0015] Optionally, in the second direction, the first connection portion is located between an end of the dummy finger group and the corresponding bus bar, and an extension length of the first connection portion is smaller than an extension length of the first dummy finger or the second dummy finger.

[0016] Optionally, the pseudo finger group also includes a second connecting portion and a third connecting portion; the second connecting portion is located in the gap between the first pseudo finger and the adjacent electrode finger, and extends along the first direction to connect the first pseudo finger with the adjacent electrode finger; the third connecting portion is located in the gap between the second pseudo finger and the adjacent electrode finger, and extends along the first direction to connect the second pseudo finger with the adjacent electrode finger.

[0017] Optionally, in the second direction, the second connection portion and / or the third connection portion is located between the end of the fake finger group and the corresponding bus bar, and an extension length of the second connection portion and / or the third connection portion is smaller than an extension length of the first fake finger and / or the second fake finger.

[0018] Optionally, in the second direction, the second connection portion and the third connection portion are at the same position.

[0019] Optionally, in the second direction, the second connection portion and the third connection portion are at different positions.

[0020] Optionally, the pseudo finger group includes at least one third pseudo finger, and the third pseudo finger is arranged between the first pseudo finger and the second pseudo finger, and is symmetrically arranged with the first pseudo finger and / or the second pseudo finger.

[0021] Optionally, the IDT electrode also includes a load unit, which includes a plurality of first loads and second loads that are spaced apart from each other and symmetrically arranged in the first direction and / or the second direction, and the first loads and the second loads are both connected to the two sides of the electrode finger in the first direction; wherein the first load is arranged at the end of the electrode finger, and the second load is arranged between the end of the electrode finger and the corresponding bus bar.

[0022] Optionally, the surface acoustic wave device further includes a reflection gate electrode, which is formed on the substrate and spaced apart on both sides of the IDT electrode along the first direction.

[0023] Optionally, the two relatively arranged interdigitated electrodes form a central overlap area, an edge gap area and an edge false finger area with the center line of the second direction pointing to the bus bars on both sides; the propagation speed of the surface acoustic wave formed by the excitation of the IDT electrode along the first direction decreases in the edge gap area, the central overlap area, and the edge false finger area in sequence.

[0024] The surface acoustic wave device with lateral mode suppression effect provided by the present application includes at least the following beneficial effects:

[0025] The present application provides a surface acoustic wave device with a transverse mode suppression effect, the surface acoustic wave device includes a substrate and an IDT electrode, the IDT electrode is formed on the substrate, and includes two interdigitated electrodes arranged opposite to each other, each interdigitated electrode includes a bus bar, a plurality of electrode fingers and a plurality of dummy finger groups, and each dummy finger group includes at least two dummy fingers arranged at intervals. The electrode fingers of different interdigitated electrodes are arranged in a staggered and spaced manner, and the dummy finger groups and electrode fingers of the same interdigitated electrode are arranged in an alternating and spaced manner, and the end of each electrode finger is opposite to the end of a dummy finger group and maintains an interval. The present application utilizes the setting position, setting number and connection relationship between the plurality of dummy fingers in the dummy finger group, and the connection relationship between the dummy fingers and the electrode fingers, to form a plurality of different sound speed zones on the substrate in the range corresponding to the dummy fingers, and then during the operation of the surface acoustic wave device, the propagation speed of the surface acoustic wave on the substrate can be changed, thereby achieving the effect of suppressing the transverse mode and improving the Q value of the surface acoustic wave device.

[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 It is a schematic diagram of the cross-sectional structure of a first surface acoustic wave device according to an embodiment of the present application.

[0029] Figure 2 Based on Figure 1 A schematic diagram of the longitudinal cross-section structure of the first surface acoustic wave device taken along line AA.

[0030] Figure 3 Based on Figure 1 A schematic diagram of the longitudinal cross-section structure of the second surface acoustic wave device taken along line AA.

[0031] Figure 4 Based on Figure 1 Schematic diagram of the longitudinal cross-section structure of the third surface acoustic wave device taken along line AA.

[0032] Figure 5 Based on Figure 1 Schematic diagram of the longitudinal cross-section structure of the fourth surface acoustic wave device taken along line AA.

[0033] Figure 6 Schematic diagram of the cross-sectional structure of a second surface acoustic wave device according to an embodiment of the present application.

[0034] Figure 7 Schematic diagram of the cross-sectional structure of a third surface acoustic wave device according to an embodiment of the present application.

[0035] Figure 8 Based on Figure 7 A schematic diagram of the longitudinal cross-sectional structure of a surface acoustic wave device taken along line A'A'.

[0036] Fig. 9 Schematic diagram of the cross-sectional structure of a fourth surface acoustic wave device according to an embodiment of the present application.

[0037] Fig.10 Schematic diagram of the cross-sectional structure of a fifth surface acoustic wave device according to an embodiment of the present application.

[0038] Fig.11 Based on Fig. 9 Schematic diagram of the longitudinal cross-section structure of a surface acoustic wave device taken along line BB.

[0039] Fig.12 Schematic diagram of the cross-sectional structure of a sixth surface acoustic wave device according to an embodiment of the present application.

[0040] Fig.13 4 is a schematic diagram of the cross-sectional structure of a seventh surface acoustic wave device according to an embodiment of the present application.

[0041] Fig.14 Based on Fig.12 Schematic diagram of the longitudinal cross-section structure of a surface acoustic wave device taken along line CC.

[0042] Fig.15 Schematic diagram of the cross-sectional structure of an eighth surface acoustic wave device according to an embodiment of the present application.

[0043] Fig.16 Based on Fig.15 Schematic diagram of the longitudinal cross-section structure of a surface acoustic wave device taken along line DD.

[0044] Fig.17 4 is a schematic diagram of the cross-sectional structure of a ninth surface acoustic wave device according to an embodiment of the present application.

[0045] Fig.18 Based on Fig.17 Schematic diagram of the longitudinal cross-section structure of a surface acoustic wave device taken along line EE.

[0046] Fig.19 4 is a schematic diagram of the cross-sectional structure of a tenth surface acoustic wave device according to an embodiment of the present application.

[0047] Fig. 20 Based on Fig.19 Schematic diagram of the longitudinal cross-section structure of a surface acoustic wave device taken along line FF.

[0048] Fig.21 FIG. 4 is a graph showing the performance of a surface acoustic wave device according to the prior art.

[0049] Fig. 22 FIG. 4 is a performance diagram of a surface acoustic wave device according to an embodiment of the present application.

[0050] 100 substrate; 110 high acoustic velocity substrate layer; 120 high acoustic velocity material layer; 130 low acoustic velocity material layer; 140 piezoelectric material layer; 200 IDT electrode; 210 bus bar; 220 electrode finger; 230 pseudo finger group; 231 first pseudo finger; 232 second pseudo finger; 233 first connection part; 234 second connection part; 235 third connection part; 240 load unit; 241 first load; 242 second load; 300 reflection grid; 400 temperature compensation layer; 500 passivation layer. DETAILED DESCRIPTION

[0051] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0052] A surface acoustic wave (SAW) device is an acoustic device widely used in the radio frequency field, including a surface acoustic wave resonator or a surface acoustic wave filter. It combines low insertion loss and good suppression performance with a small size and mainly uses the piezoelectric effect to convert electrical energy and mechanical energy into each other.

[0053] For conventional SAW devices, surface acoustic waves propagating laterally along the length direction of the finger will form a transverse resonant mode on the substrate, that is, a transverse mode that appears in and near the passband. This transverse mode will increase the device loss, cause the Q value to fluctuate greatly, and reduce the performance of the SAW device (resonator, filter). Therefore, the prior art suppresses the transverse mode by increasing the mass load at the end of the finger, such as providing a thickened (piston structure) and / or widened (hammerhead structure) metal end at the end of the finger, or tilting the electrode finger to reduce the speed of sound in this area. However, although the method of adding a suppression load to the finger end of the electrode finger can achieve a certain transverse mode (transverse mode) suppression effect, this method is sensitive to the size and weight of the suppression load, and has high requirements for the processing technology, increasing the process cost. At the same time, direct processing of the finger end will also affect the propagation of the main mode to a certain extent, resulting in a reduction in the Q value.

[0054] Based on the above problems, the present application provides a surface acoustic wave device with a lateral mode suppression effect. By setting a dummy finger group between adjacent electrode fingers, and utilizing the setting positions, setting numbers, and connection relationships of multiple dummy fingers in the dummy finger group, multiple different sound speed zones are formed within the range corresponding to the dummy fingers. Therefore, during the operation of the surface acoustic wave device, the propagation speed of the surface acoustic wave on the substrate can be changed, thereby achieving the effect of suppressing the lateral mode and improving the Q value of the surface acoustic wave device.

[0055] According to one aspect of the present application, a surface acoustic wave device having a lateral mode suppression effect is provided, such as Figures 1 to 20As shown, the surface acoustic wave device includes a substrate 100 and an IDT electrode 200 (interdigital transducer). For the convenience of description, the propagation direction of the surface acoustic wave is set as the first direction, that is, the X direction in the figure, the direction in which the fingers of the IDT electrode 200 extend is set as the second direction, that is, the Y direction in the figure, and the direction of the stack thickness of the surface acoustic wave device is set as the third direction, that is, the Z direction in the figure. The first direction and the second direction are orthogonal to each other and parallel to the surface of the substrate 100, and the third direction is perpendicular to the first direction and the second direction respectively.

[0056] The IDT electrode 200, as the most basic unit constituting the surface acoustic wave device, can be composed of a high-density conductive metal or alloy material, including but not limited to one of titanium, chromium, copper, silver, aluminum, platinum, tungsten, molybdenum and other metals or their metal alloys, and can be a single-layer metal film or a laminated metal film with multiple metal layers stacked. In the present application, the IDT electrode 200 preferably uses a laminate of metal titanium and aluminum, and the metal aluminum film is formed on the metal titanium film. In addition, the substrate 100 on both sides of the IDT electrode 200 along the first direction also includes a reflective grid 300.

[0057] In some embodiments, Figure 1 and Figure 2 As shown, the IDT electrode 200 is formed on the substrate 100 and includes two interdigitated electrodes arranged opposite to each other. Each interdigitated electrode includes a bus bar 210 extending along a first direction, and a plurality of electrode fingers 220 and a dummy finger group 230 extending from one side of the bus bar 210 along a second direction.

[0058] In the first direction, the electrode fingers 220 of different interdigitated electrodes are arranged alternately and spaced apart, and the pseudo-finger groups 230 and electrode fingers 220 of the same interdigitated electrode are arranged alternately and spaced apart, and each pseudo-finger group 230 includes at least two pseudo-finger groups arranged at intervals; in the second direction, the end of the electrode finger 220 of one interdigitated electrode is spaced apart from the end of the pseudo-finger group 230 of another interdigitated electrode.

[0059] It is understandable that the surface acoustic wave is a typical elastic wave, and the surface acoustic wave device can be excited to form a surface acoustic wave by applying an AC voltage to the IDT electrode 200. When the surface acoustic wave propagates in a substance, it encounters an interface between different media (with different sound propagation velocities), which will reflect the surface acoustic wave that is not parallel to the interface, thereby avoiding the formation of resonance of stray waves, thereby reducing energy loss.

[0060] According to the relationship between the propagation speed of elastic waves in the medium and impedance, Z = ρC, where Z is the acoustic impedance, ρ is the medium density, and C is the speed of sound. From the formula, it can be seen that the greater the density of the propagation medium, the greater the acoustic impedance, that is, the greater the resistance encountered by elastic waves when propagating in the medium.

[0061] The present application arranges the pseudo-finger group 230 and the electrode finger 220 of the same interdigital electrode alternately and at intervals, and sets each pseudo-finger group 230 to include at least two pseudo-finger groups arranged at intervals, and keeps a certain interval between the end of each pseudo-finger and the end of the electrode finger 220 of the other relative difference electrode, so that the surface acoustic wave can form multiple different sound speed zones between the end of the electrode finger 220 and the bus bar 210 of the other relative interdigital electrode, thereby effectively suppressing the transverse mode of the surface acoustic wave device and avoiding the excitation of transverse mode resonance. As a result, the surface acoustic wave can be better concentrated in the area close to the center of the electrode finger 220, thereby improving the Q value of the surface acoustic wave device and improving the device performance.

[0062] As an example, two interdigitated electrodes arranged opposite to each other on the substrate 100 may include a first interdigitated electrode and a second interdigitated electrode, the first interdigitated electrode including a first bus bar extending in a first direction and a plurality of first electrode fingers and a first dummy finger group extending in a second direction and alternately arranged in the first direction; the second interdigitated electrode including a second bus bar extending in the first direction and a plurality of second electrode fingers and a second dummy finger group extending in the second direction and alternately arranged in the first direction. The first electrode finger group and the first dummy finger group extend from one side of the first bus bar to one side of the second bus bar and are spaced from the second bus bar, and the second electrode fingers and the second dummy finger group extend from one side of the second bus bar to one side of the first bus bar and are spaced from the first bus bar.

[0063] Among them, the first electrode fingers and the second electrode fingers are arranged in staggered compartments, the first fake finger group is located between the end of the second electrode finger and the first bus bar, is arranged opposite to the second electrode fingers, and corresponds one to one, and in the second direction, a gap is left between the end of the first fake finger group and the end of the second electrode finger; similarly, the second fake finger group is located between the end of the first electrode finger and the second bus bar, is arranged opposite to the first electrode fingers, and corresponds one to one, and in the second direction, a gap is left between the end of the second fake finger group and the end of the first electrode finger.

[0064] Thus, the first interdigitated electrodes and the second interdigitated electrodes arranged opposite to each other can form a plurality of acoustic velocity zones on the substrate 100 in the second direction and from the center line of the two interdigitated electrodes to the bus bars 210 on both sides. Among them, the region where the first electrode fingers and the second electrode fingers overlap along the first direction can be set as the central overlap region Z3, the gap region between the first dummy finger group and the second electrode finger and / or the second dummy finger group and the first electrode finger can be set as the edge gap region Z2, and the region corresponding to the extension of the first dummy finger group and / or the second dummy finger group along the second direction can be set as the edge dummy finger region Z1.

[0065] Therefore, when the surface acoustic wave excited by the IDT electrode 200 propagates along the first direction, its propagation speed is the largest in the edge gap area Z2 and the smallest in the edge dummy finger area Z1, and the propagation speed in the central overlap area Z3 is between the edge gap area Z2 and the edge dummy finger area Z1. In particular, the dummy finger group 230 is set to include at least two dummy fingers spaced apart in the second direction, thereby effectively suppressing the transverse mode of the surface acoustic wave device and avoiding the excitation of transverse mode resonance, so that the surface acoustic wave can be better concentrated in the central overlap area Z3 of the electrode finger 220, thereby improving the Q value of the surface acoustic wave device and enhancing the device performance.

[0066] It should be noted that the above-mentioned surface acoustic wave device can be a common surface acoustic wave device, i.e., STD-SAW (Standard Surface Acoustic Wave), or a surface acoustic wave device based on a POI (Piezoelectric on Insulator, piezoelectric material on insulator) substrate, i.e., POI-SAW, or a temperature compensated surface acoustic wave device, i.e., TC-SAW (Temperature Compensation Surface Acoustic Wave, TC-SAW). The present application does not specifically limit the specific type of the surface acoustic wave device.

[0067] As an example, when the surface acoustic wave device is a POI-SAW, the substrate 100 may be a laminated substrate including a piezoelectric material layer 140, such as Figure 3 and Figure 4 As shown, the IDT electrode 200 is formed on the piezoelectric material layer 140. The stacked substrate may be a stacked substrate in which a low acoustic velocity material layer 130 and a piezoelectric material layer 140 are stacked in sequence on a high acoustic velocity substrate layer 110, or a stacked substrate in which a high acoustic velocity material layer 120, a low acoustic velocity material layer 130 and a piezoelectric material layer 140 are stacked in sequence on a high acoustic velocity substrate layer 110.

[0068] Specifically, the piezoelectric material layer 140 includes, but is not limited to, one of the materials such as LiTaO3 (lithium tantalate), LiNbO3 (lithium niobate), quartz, zinc oxide (ZnO), and aluminum nitride (AlN) in various cuts. In this embodiment, the piezoelectric material layer 140 preferably uses lithium niobate or lithium tantalate, which has advantages such as excellent piezoelectric effect and electromechanical coupling effect, and has been widely used in surface acoustic wave devices.

[0069] The low acoustic velocity material layer 130 is a film layer with a relatively low acoustic velocity, so that the propagation speed of the surface acoustic wave in the low acoustic velocity material layer 130 is lower than the propagation speed of the surface acoustic wave in the piezoelectric material layer 140. The low acoustic velocity material layer 130 includes, but is not limited to, one of silicon oxide, glass, silicon oxynitride, tantalum oxide, etc., or a material with a compound obtained by adding fluorine, carbon or boron to silicon oxide as the main component. In this embodiment, the low acoustic velocity material layer 130 preferably uses a silicon oxide film (SiOx), such as a SiO2 film.

[0070] The high acoustic velocity material layer 120 is a film layer with a relatively high acoustic velocity, so that the propagation speed of the surface acoustic wave in the high acoustic velocity material layer 120 is higher than the propagation speed of the surface acoustic wave in the piezoelectric material layer 140. The high acoustic velocity material layer 120 includes, but is not limited to, a medium using one of silicon nitride, aluminum nitride, zinc oxide, silicon oxynitride, sapphire, aluminum oxide, etc. as a main component. In this embodiment, the high acoustic velocity material layer 120 is an aluminum nitride film (AlN).

[0071] The high acoustic velocity substrate layer 110 is used as a supporting base of the piezoelectric substrate 100, including but not limited to using one of alumina, lithium tantalate, lithium niobate, piezoelectrics such as quartz, alumina, sapphire, magnesium oxide, silicon nitride, aluminum nitride, silicon carbide, zirconium oxide, cordierite, mullite, steatite, forsterite and other ceramics, diamond, glass and other dielectrics, gallium nitride and other semiconductors or resins, etc. In this embodiment, the high acoustic velocity substrate layer 110 preferably uses a silicon substrate.

[0072] As an example, when the surface acoustic wave device is a TC-SAW, the substrate 100 may be a piezoelectric material layer 140, such as Figure 5 As shown, the IDT electrode 200 is formed on the piezoelectric material layer 140. At the same time, after the IDT electrode 200 is formed on the piezoelectric material layer 140, a temperature compensation layer 400 is formed on the piezoelectric material layer 140 to completely cover the IDT electrode 200, and a passivation layer 500 is formed on the temperature compensation layer 400 to cover the upper surface of the temperature compensation layer 400.

[0073] The temperature compensation layer 400 is composed of a material that can provide a positive temperature coefficient, including but not limited to a combination of one or more of silicon dioxide, germanium dioxide, and silicon oxyfluoride. Since ordinary SAW devices are easily affected by temperature changes, a layer of temperature compensation material with a positive frequency temperature coefficient can be applied to form a TC-SAW with temperature compensation function, thereby improving the temperature drift phenomenon.

[0074] The passivation layer 500 is made of a material with stable properties, including but not limited to silicon nitride, and is used to protect and isolate the surface of the temperature compensation layer 400 .

[0075] In some embodiments, Figure 1 As shown, each pseudo finger group 230 includes at least a first pseudo finger 231 and a second pseudo finger 232, and the first pseudo finger 231 and the second pseudo finger 232 are arranged in a spaced relationship along the first direction, and are spaced in a second direction from the ends of the corresponding electrode fingers 220. By flexibly adjusting the arrangement positions of the first pseudo finger 231 and the second pseudo finger 232 in the second direction, and the extension lengths thereof in the first direction, the sound velocity zone distribution of the surface acoustic wave in the edge pseudo finger zone Z1 can be adaptively adjusted, so that when the surface acoustic wave propagates in different pseudo fingers, the surface acoustic wave that is not parallel to the interface direction can be reflected, so as to avoid the formation of resonance of stray waves, thereby playing a role in reducing energy loss.

[0076] The maximum gap distance between the first pseudo finger 231 and the second pseudo finger 232 in the first direction should be equal to the difference between the gap distance between two adjacent electrode fingers 220 of the same interdigital electrode and the width of the first pseudo finger 231 and the second pseudo finger 232, such as Figure 6 Thus, when the distance between the first dummy finger 231 and the second dummy finger 232 is the largest, the first dummy finger 231 overlaps with two adjacent sides of the adjacent electrode finger 220 , and the second dummy finger 232 overlaps with two adjacent sides of the adjacent electrode finger 220 tangent to each other.

[0077] As an example, the central axis of the first pseudo finger 231 and the second pseudo finger 232 along the second direction are respectively at the same distance from the central axis of the corresponding electrode finger 220 along the second direction. Therefore, when the first pseudo finger 231 and the second pseudo finger 232 have the same extension length in the second direction, the first pseudo finger 231 and the second pseudo finger 232 can be symmetrical with each other about the central axis of the electrode finger 220 corresponding and spaced in the second direction. By arranging the first pseudo finger 231 and the second pseudo finger 232 symmetrically in the second direction, the first pseudo finger 231 and the second pseudo finger 232 can be adjusted between two adjacent electrode fingers 220 of the same interdigitated electrode in the process of position adjustment, so that the surface acoustic wave can change regularly when propagating along the edge pseudo finger area Z1, so as to facilitate the adaptive adjustment of the appropriate gap distance between the first pseudo finger 231 and the second pseudo finger 232 to avoid the excitation of the transverse mode resonance.

[0078] On the contrary, if Figure 6 and Figure 7 As shown, when the extension lengths of the first pseudo finger 231 and the second pseudo finger 232 in the second direction may also be different, the first pseudo finger 231 and the second pseudo finger 232 of different lengths can separate the corresponding edge pseudo finger area Z1 into two independent sound speed areas in the second direction, thereby achieving the purpose of finely adjusting the propagation speed of the surface acoustic wave in the edge pseudo finger area Z1.

[0079] It should be noted that the present application does not specifically limit the setting position and extension length of the first fake finger 231 and the second fake finger 232 in the first direction. The first fake finger 231 and the second fake finger 232 can be symmetrically arranged or asymmetrically arranged.

[0080] In some embodiments, Figures 9 to 11 As shown, each pseudo finger group 230 may further include a first connecting portion 233 , and the first connecting portion 233 is located in the gap between the first pseudo finger 231 and the second pseudo finger 232 , and extends along the first direction to connect two adjacent sides between the first pseudo finger 231 and the second pseudo finger 232 .

[0081] By setting a first connecting portion 233 between the first dummy finger 231 and the second dummy finger 232 to connect the first dummy finger 231 and the second dummy finger 232, the propagation speed of the surface acoustic wave in the edge dummy finger area Z1 can be further adjusted, and the surface acoustic wave can further form multiple sound speed zones in the edge dummy finger area Z1 in the second direction, so that the dummy finger group 230 can not only play the effect of transverse mode suppression, but also reflect various stray waves, which are not easily excited to form transverse mode resonance, thereby avoiding additional energy dissipation, thereby further improving the performance of the surface acoustic wave device.

[0082] In order to further improve the transverse mode suppression effect of the surface acoustic wave device, the specific position of the first connecting portion 233 in the second direction can be adjusted to finely adjust the propagation speed of the surface acoustic wave in the edge finger area Z1, so as to suppress the transverse mode without affecting the main acoustic mode, reflect various stray waves, avoid additional energy dissipation, and thus improve the performance of the surface acoustic wave device.

[0083] In addition, the extension length of the first connection portion 233 in the second direction should be smaller than the extension length of the first dummy finger 231 or the second dummy finger 232, so that the first connection portion 233 can be located between the end of the dummy finger group 230 and the connection end of the corresponding bus bar 210. In other words, the first connection portion 233 can be arranged at a position corresponding to the end of the first dummy finger 231 and / or the second dummy finger 232, or can be arranged to correspond to one end of the bus bar 210 connected to the first dummy finger 231 and / or the second dummy finger 232.

[0084] In some embodiments, Figure 12 to Figure 16 As shown, each dummy finger group 230 may further include a second connection portion 234 and a third connection portion 235. The second connection portion 234 is located in the gap between the first dummy finger 231 and the adjacent electrode finger 220, and extends along the first direction to connect the first dummy finger 231 to the side between the adjacent electrode fingers 220; the third connection portion 235 is located in the gap between the second dummy finger 232 and the adjacent electrode finger 220, and extends along the first direction to connect the second dummy finger 232 to the side between the adjacent electrode fingers 220.

[0085] By setting the second connection part 234 and the third connection part 235, the first dummy finger 231 and the second dummy finger 232 are respectively connected to the sides of the adjacent electrode finger 220, which can also play a role in adjusting the propagation speed of the surface acoustic wave in the edge dummy finger area Z1. Cutting the second connection part 234 and the third connection part 235 in the second direction will make the surface acoustic wave further form multiple sound speed zones in the edge dummy finger area Z1, so that the dummy finger group 230 can not only play the effect of transverse mode suppression, but also reflect various stray waves, which are not easily excited to form transverse mode resonance, thereby avoiding additional energy dissipation, thereby further improving the performance of the surface acoustic wave device.

[0086] In order to further improve the transverse mode suppression effect of the surface acoustic wave device, the specific positions of the second connecting part 234 and the third connecting part 235 in the second direction can be adjusted to finely adjust the propagation speed of the surface acoustic wave in the edge finger area Z1, so as to suppress the transverse mode without affecting the main acoustic mode, reflect various stray waves, avoid additional energy dissipation, and thus improve the performance of the surface acoustic wave device.

[0087] In addition, the extension length of the second connection portion 234 and the third connection portion 235 in the second direction should be smaller than the extension length of the first dummy finger 231 or the second dummy finger 232, so that the second connection portion 234 can be located between the end of the first dummy finger 231 and the connection end of the corresponding bus bar 210, and the third connection portion 235 can be located between the end of the second dummy finger 232 and the connection end of the corresponding bus bar 210. In other words, the second connection portion 234 and the third connection portion 235 can be arranged at positions corresponding to the ends of the first dummy finger 231 and / or the second dummy finger 232, or can be arranged at one end of the bus bar 210 connected to the first dummy finger 231 and / or the second dummy finger 232.

[0088] Meanwhile, the second connection portion 234 and the third connection portion 235 may be disposed at the same position in the second direction, such as Fig.12 and Fig.13 As shown, it can also be different, such as Fig.15 When the second connection portion 234 and the third connection portion 235 are disposed at the same position in the second direction, the second connection portion 234 and the third connection portion 235 together form an independent sound velocity zone in the edge pseudo-finger zone Z1, as shown in FIG. Fig.14 When the second connection portion 234 and the third connection portion 235 are arranged at different positions in the second direction, the second connection portion 234 and the third connection portion 235 are spaced apart in the edge pseudo-finger area Z1 to form two independent sound speed zones, such as Fig.16 As shown, the purpose of finely adjusting the propagation speed of the surface acoustic wave in the edge pseudo-finger area Z1 is achieved.

[0089] In some embodiments, Fig.17 and Fig.18 As shown, each pseudo finger group 230 may further include at least one or more third pseudo fingers, and the third pseudo fingers are arranged between the first pseudo fingers 231 and the second pseudo fingers 232, and are symmetrically arranged with the first pseudo fingers 231 and / or the second pseudo fingers 232.

[0090] When the pseudo finger group 230 includes one third pseudo finger, the third pseudo finger is located at the center of the first pseudo finger 231 and the second pseudo finger 232 along the first direction, and is equal to the gap distance between the first pseudo finger 231 and the second pseudo finger 232. When the pseudo finger group 230 includes a plurality of third pseudo fingers, the plurality of third pseudo fingers are arranged at equal intervals in the first direction, and the gap distances between the first pseudo finger 231 and the second pseudo finger 232 and their adjacent third pseudo fingers are equal to the gap distances between the third pseudo fingers.

[0091] Furthermore, a connection portion may also be provided in the gap between different third pseudo fingers to connect adjacent third pseudo fingers, or a connection portion may be provided in the gap between the third pseudo finger and the first pseudo finger 231 and the second pseudo finger 232 to connect the third pseudo finger to the first pseudo finger 231 and the third pseudo finger to the second pseudo finger 232, so as to finely adjust the propagation speed of the surface acoustic wave in the edge pseudo finger zone Z1 (not shown in the figure). The specific setting positions of different connection portions in the second direction are not specifically limited by the present application, and can be flexibly adjusted according to the extension length of the pseudo finger group 230 in the second direction.

[0092] In some embodiments, Fig.19 and Fig. 20 As shown, the IDT electrode 200 may further include a load unit 240. The load unit 240 includes a plurality of first loads 241 and second loads 242 that are spaced apart from each other in the first direction and / or the second direction and are symmetrically arranged. The first loads 241 and the second loads 242 are both connected to the two sides of the electrode finger 220 in the first direction; and the first load 241 is arranged at the end of the electrode finger 220, and the second load 242 is arranged between the end of the electrode finger 220 and the corresponding bus bar 210, and is opposite to the first load 241 in the first direction and is spaced apart from each other.

[0093] By forming the first load 241 and the second load 242 on each electrode finger 220 simultaneously while the IDT electrode 200 is being formed, the first load 241 and the second auxiliary load can be integrally formed with the electrode finger 220 to form a whole, which is equivalent to widening the two different positions of the electrode finger 220 along the first direction to further adjust the propagation speed of the surface acoustic wave in the central overlapping area Z3, thereby improving the performance of the surface acoustic wave device.

[0094] It should be noted that Fig.19 The combination of a fake finger group 230 structure and a load unit 240 unit is shown, which is only used as an example in the present application and should not be regarded as a limitation of the present application. That is to say, any structure of the fake finger group 230 described in any of the above embodiments can be combined with the load unit 240 to form a new IDT electrode 200 structure, which is not listed one by one here.

[0095] In addition, in the above embodiments, the first fake finger 231 and the second fake finger 232 are uniformly set to be a mutually symmetrical structure, which is only used as an example in the present application and should not be regarded as a limitation of the present application. That is, the fake finger group 230 of any structure described in any of the above embodiments can be replaced by a fake finger group 230 consisting of a first fake finger 231 and a second fake finger 232 having different extension lengths along the second direction. Figure 7 The pseudo finger group 230 is shown, and they are not listed one by one here.

[0096] In order to further illustrate the transverse mode suppression effect of the surface acoustic wave device provided in the present application, the surface acoustic wave device in the present application can be applied to a specific scenario, for example, the surface acoustic wave device is applied to a resonator or a filter, and the performance graph of the resonator or the filter is viewed. If there are many parasitic resonance peaks in the graph, it can be indicated that the resonator or the filter has strong transverse mode ripples, the passband clutter is serious, and the use of the surface acoustic wave device will lead to the deterioration of the overall device performance.

[0097] As an example, the existing surface acoustic wave device structure and the surface acoustic wave device structure of the present application can be applied to the resonator for performance comparison. The comparison results are as follows: Fig.21 and Fig. 22 As shown, Fig.21 This is a performance diagram of a resonator using a conventional surface acoustic wave device structure that does not have a transverse mode suppression effect. Fig. 22 For application of this application Fig.19 Performance diagram of the resonator of the surface acoustic wave device structure in the embodiment. Fig.21 and Fig. 22 The comparison shows that Fig. 22 The admittance curves are smoother and Fig.21 Medium admittance curve, Fig. 22 The number of parasitic resonance peaks in the medium admittance curve is almost invisible, which means that the surface acoustic wave device provided in the present application can effectively suppress the transverse mode in the resonator, further improve the Q value of the resonator or filter, and significantly improve the performance of the resonator or filter.

[0098] In addition, the surface acoustic wave device with transverse mode suppression effect according to any of the above embodiments disclosed herein can also be provided in or integrated into any processor-based device. Examples include, but are not limited to, set-top boxes, entertainment units, navigation devices, communication devices, fixed position data units, mobile position data units, global positioning system (GPS) devices, mobile phones, cellular phones, smart phones, session initiation protocol (SIP) phones, tablet computers, tablet phones, servers, computers, portable computers, mobile computing devices, wearable computing devices (e.g., smart watches, health or fitness trackers, glasses, etc.), desktop computers, personal digital assistants (PDAs), monitors, computer monitors, televisions, tuners, radios, satellite radios, music players, digital music players, portable music players, digital video players, video players, digital video disc (DVD) players, portable digital video players, automobiles, vehicle components, avionics systems, drones, and multirotor aircraft.

[0099] In summary, the present application provides a surface acoustic wave device with a transverse mode suppression effect, the surface acoustic wave device includes a substrate 100 and an IDT electrode 200, the IDT electrode 200 is formed on the substrate 100, and includes two interdigitated electrodes arranged opposite to each other, each interdigitated electrode includes a bus bar 210, a plurality of electrode fingers 220 and a plurality of dummy finger groups 230, and each dummy finger group 230 includes at least two dummy fingers arranged at intervals. The electrode fingers 220 of different interdigitated electrodes are arranged in a staggered interval, and the dummy finger groups 230 and electrode fingers 220 of the same interdigitated electrode are arranged in an alternating interval, and the end of each electrode finger 220 is opposite to the end of a dummy finger group 230 and keeps an interval. The present application utilizes the setting positions, setting numbers and connection relationships between multiple dummy fingers in the dummy finger group 230, as well as the connection relationship between the dummy fingers and the electrode fingers 220, to form multiple different sound speed zones on the substrate 100 in the range corresponding to the dummy fingers, and then during the operation of the surface acoustic wave device, it is possible to change the propagation speed of the surface acoustic wave on the substrate 100, thereby suppressing the lateral mode and improving the Q value of the surface acoustic wave device.

[0100] In the description of the aforementioned embodiments, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0101] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. A surface acoustic wave device having a transverse mode suppression effect, characterized in that: include: substrate; The IDT electrode comprises two interdigitated electrodes arranged opposite to each other on the substrate; each of the interdigitated electrodes comprises a bus bar extending along a first direction, and a plurality of electrode fingers and a dummy finger group extending from one side of the bus bar along a second direction, each of the dummy finger groups comprises at least two dummy fingers spaced apart in the first direction, the second direction is orthogonal to the first direction, and the orthogonal plane is parallel to the surface of the substrate; Among them, in the first direction, the electrode fingers of different interdigitated electrodes are arranged in an alternating manner, and the pseudo-finger group and the electrode fingers of the same interdigitated electrode are arranged in an alternating manner; in the second direction, the end of an electrode finger and the end of a pseudo-finger group are spaced apart from each other and correspond one to one.

2. The surface acoustic wave device according to claim 1, characterized in that The pseudo finger group includes at least a first pseudo finger and a second pseudo finger, and the center axes of the first pseudo finger and the second pseudo finger along the second direction are respectively at the same distance from the center axes of the corresponding electrode fingers along the second direction.

3. The surface acoustic wave device according to claim 2, characterized in that The first pseudo finger and the second pseudo finger have different extension lengths in the second direction.

4. The surface acoustic wave device according to claim 2, characterized in that: The first dummy finger and the second dummy finger are symmetrical to each other about the central axis of the corresponding electrode finger in the second direction.

5. The surface acoustic wave device according to claim 2, wherein: The maximum gap distance between the first dummy finger and the second dummy finger in the first direction is equal to the difference between the gap distance between two adjacent electrode fingers of the same interdigitated electrode and the width of the first dummy finger and the second dummy finger.

6. The surface acoustic wave device according to claim 2, characterized in that: The pseudo finger group further includes a first connecting portion, which is located in a gap between the first pseudo finger and the second pseudo finger and extends along the first direction to connect the first pseudo finger and the second pseudo finger.

7. The surface acoustic wave device according to claim 6, characterized in that In the second direction, the first connection portion is located between an end of the dummy finger group and the corresponding bus bar, and an extension length of the first connection portion is smaller than an extension length of the first dummy finger or the second dummy finger.

8. The surface acoustic wave device according to claim 2, characterized in that: The pseudo finger group also includes a second connecting portion and a third connecting portion; the second connecting portion is located in the gap between the first pseudo finger and the adjacent electrode finger, and extends along the first direction to connect the first pseudo finger with the adjacent electrode finger; the third connecting portion is located in the gap between the second pseudo finger and the adjacent electrode finger, and extends along the first direction to connect the second pseudo finger with the adjacent electrode finger.

9. The surface acoustic wave device according to claim 8, characterized in that: In the second direction, the second connection portion and / or the third connection portion is located between the end of the dummy finger group and the corresponding bus bar, and an extension length of the second connection portion and / or the third connection portion is less than an extension length of the first dummy finger and / or the second dummy finger.

10. The surface acoustic wave device according to claim 8, characterized in that In the second direction, the second connection portion and the third connection portion are located at the same position.

11. The surface acoustic wave device according to claim 8, characterized in that In the second direction, the second connection portion and the third connection portion are at different positions.

12. The surface acoustic wave device according to claim 2, wherein: The pseudo finger group includes at least one third pseudo finger, and the third pseudo finger is arranged between the first pseudo finger and the second pseudo finger, and is symmetrically arranged with the first pseudo finger and / or the second pseudo finger.

13. The surface acoustic wave device according to claim 1, wherein: The IDT electrode also includes a load unit, which includes a plurality of first loads and second loads that are spaced apart from each other and symmetrically arranged in the first direction and / or the second direction, and the first loads and the second loads are both connected to the two sides of the electrode finger in the first direction; wherein the first load is arranged at the end of the electrode finger, and the second load is arranged between the end of the electrode finger and the corresponding bus bar.

14. The surface acoustic wave device according to claim 1, wherein: The surface acoustic wave device further includes a reflection gate electrode formed on the substrate and spaced apart on both sides of the IDT electrode along the first direction.

15. The surface acoustic wave device according to claim 1, wherein: The two interdigitated electrodes arranged opposite to each other form a central overlap area, an edge gap area and an edge false finger area with the center line of the second direction pointing to the bus bars on both sides; the propagation speed of the surface acoustic wave formed by the excitation of the IDT electrode along the first direction decreases in the edge gap area, the central overlap area, and the edge false finger area in sequence.

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