Surface acoustic wave device structure and device

Abstract

The invention provides a surface acoustic wave device structure and device, the surface acoustic wave device structure comprises a substrate and an IDT electrode, the IDT electrode is formed on the substrate and comprises two interdigital electrodes which are oppositely arranged, each interdigital electrode comprises a bus bar and a plurality of electrodes, and electrode fingers of different interdigital electrodes are arranged at intervals in a staggered manner. Each electrode finger at least comprises a first metal layer and a second metal layer which are stacked in sequence, and the thickness of the first metal layer in the first region is not smaller than the thickness of the first metal layer in the second region. The propagation velocity of the surface acoustic wave formed by excitation of the IDT electrode is greater than the propagation velocity of the surface acoustic wave formed by excitation of the IDT electrode in the first area, and the effect is equivalent to increase of a suppression load at the extension end of the electrode finger, so that the effect of suppressing a transverse mode can be achieved, and the Q value of the surface acoustic wave device is improved; and the processing technology requirement of the surface acoustic wave device structure is greatly reduced, and the technology cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of surface acoustic wave, and particularly relates to a surface acoustic wave device structure and apparatus. Background Art

[0002] The basic structure of a surface acoustic wave (SAW) device is to fabricate an acoustic-electric transducer on a piezoelectric substrate material. It has the advantages of small volume, large bandwidth, low insertion loss, low cost, mass production, etc., and is widely used in mobile communication devices. With the development of communication protocols, the requirements for radio frequency 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, during the use of existing surface acoustic wave devices, unnecessary lateral mode spurs (or lateral resonance modes, transverse modes, etc.) will be excited. The spurious responses 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 structure and apparatus with a lateral mode suppression effect, which can suppress the influence of transverse modes on the performance of the surface acoustic wave device, improve the Q value, has become one of the technical problems that need to be solved urgently by those skilled in the art. Summary of the Invention

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

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

[0007] To achieve the above object, the first aspect embodiment of the present application proposes a surface acoustic wave device structure, including:

[0008] A substrate;

[0009] An IDT electrode, at least including a pair of interdigital electrodes oppositely arranged on the substrate; each interdigital electrode includes a bus bar extending along a first direction, and a plurality of electrode fingers extending from one end of the bus bar along a second direction, and the electrode fingers of different interdigital electrodes are alternately arranged at intervals in the first direction;

[0010] Wherein, each of the electrodes refers to at least a first metal layer and a second metal layer stacked in a third direction, the second metal layer is located on the first metal layer, and the mass density of the first metal layer is greater than that of the second metal layer; each of the electrodes further refers to at least a first region and a second region that are connected in the second direction and have the same thickness, and the thickness of the first metal layer in the first region is not less than its thickness in the second region; the second direction is orthogonal to the first direction, and the third direction is perpendicular to the orthogonal plane of the first direction and the second direction.

[0011] Optionally, the thickness of the first metal layer in the first region is greater than its thickness in the second region, and the thickness of the second metal layer in the first region is less than its thickness in the second region.

[0012] Optionally, the thickness of the first metal layer in the first region is the same as its thickness in the second region, and at least one groove extending in the second direction is further provided in the second region of the first metal layer, and the second metal layer is located on the first metal layer and fills the groove.

[0013] Optionally, the extension width of the groove in the first direction is not greater than the line width of the electrode finger, and in the third direction, the vertical projection of the groove in the third direction is located within the second region.

[0014] Optionally, the first metal layer includes a first surface and a second surface opposite to each other in the third direction, the second surface is in contact with the substrate, and the groove extends a preset depth from the first surface to one side of the second surface.

[0015] Optionally, the preset depth of the groove extending from the first surface to one side of the second surface is not greater than the thickness of the first metal layer.

[0016] Optionally, a plurality of grooves are provided on the first metal layer in the second region, and the plurality of grooves are sequentially spaced along the second direction.

[0017] Optionally, the central axis of each electrode finger along the second direction overlaps with the central axis of the groove corresponding to the second region along the second direction.

[0018] Optionally, the electrode finger includes a stack formed by a plurality of the first metal layers and the second metal layers.

[0019] Optionally, each of the interdigital electrodes further includes a plurality of dummy fingers, which extend from one side of the bus bar along the second direction, are alternately arranged at intervals in the first direction between adjacent electrode fingers, and in the second direction, the extending ends of each dummy finger are spaced apart from and correspond to one by one the extending ends of one electrode finger.

[0020] Optionally, the surface acoustic wave device structure further includes reflection grating electrodes, which are formed on the substrate and are formed at intervals along the first direction on both sides of the IDT electrodes.

[0021] Optionally, each of the reflection grating electrodes includes a plurality of connecting finger bars extending along the second direction, and at least one first groove extending along the second direction is provided on each connecting finger bar, and the vertical projection of the first groove in the third direction is located within the vertical projection plane of the corresponding connecting finger bar.

[0022] To achieve the above object, an embodiment of the second aspect of the present application provides a surface acoustic wave device, which includes the surface acoustic wave device structure described in any one of the above.

[0023] The surface acoustic wave device structure and device provided by the present application at least have the following beneficial effects:

[0024] The present application provides a surface acoustic wave device structure and device, which includes a substrate and IDT electrodes. The IDT electrodes are formed on the substrate and include two interdigital electrodes arranged oppositely. Each interdigital electrode includes a bus bar and a plurality of electrode fingers, and the electrode fingers of different interdigital electrodes are arranged alternately at intervals. By setting each electrode finger of the IDT electrode to at least include a first metal layer and a second metal layer stacked in sequence, and setting the thickness of the first metal layer in the first region to be not less than its thickness in the second region, and using the physical property that the mass density of the first metal layer is greater than that of the second metal layer, the propagation speed of the surface acoustic wave excited by the IDT electrode shows that the propagation speed in the first region is greater than that in the second region. In effect, it is equivalent to increasing the suppression load at the extending ends of the electrode fingers, which can not only suppress the lateral mode and improve the Q value of the surface acoustic wave device, but also greatly reduce the processing technology requirements of the surface acoustic wave device structure and reduce the process cost.

[0025] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. Description of the Drawings

[0026] The above and / or additional aspects and advantages of the present application will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0027] Figure 1 It is a schematic cross-sectional structure diagram of the first surface acoustic wave device structure shown according to an embodiment of the present application.

[0028] Figure 2 It is according to Figure 1 A schematic longitudinal cross-sectional structure diagram of the first surface acoustic wave device structure taken along line AA in

[0029] Figure 3 It is a schematic cross-sectional structure diagram of the second surface acoustic wave device structure shown according to an embodiment of the present application.

[0030] Figure 4 It is according to Figure 2 A schematic longitudinal cross-sectional structure diagram of a surface acoustic wave device structure taken along line BB in

[0031] Figure 5 It is a schematic cross-sectional structure diagram of the third surface acoustic wave device structure shown according to an embodiment of the present application.

[0032] Figure 6 It is according to Figure 5 A schematic longitudinal cross-sectional structure diagram of a surface acoustic wave device structure taken along line CC in

[0033] Figure 7 It is a schematic cross-sectional structure diagram of the fourth surface acoustic wave device structure shown according to an embodiment of the present application.

[0034] Figure 8 It is a schematic cross-sectional structure diagram of the fifth surface acoustic wave device structure shown according to an embodiment of the present application.

[0035] Figure 9 It is a schematic cross-sectional structure diagram of the fifth surface acoustic wave device structure shown according to an embodiment of the present application.

[0036] Figure 10 It is according to Figure 1 A schematic longitudinal cross-sectional structure diagram of the second surface acoustic wave device structure taken along line AA in

[0037] Figure 11 It is according to Figure 1 A schematic longitudinal cross-sectional structure diagram of the third surface acoustic wave device structure taken along line AA in

[0038] Figure 12 It is according to Figure 1 A schematic longitudinal cross-sectional structure diagram of the fourth surface acoustic wave device structure taken along line AA in

[0039] Figure 13 It is a performance diagram of a surface acoustic wave device shown according to the prior art.

[0040] Figure 14It is a performance diagram of a surface acoustic wave device shown according to an embodiment of the present application.

[0041] 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; 2201 Groove; 221 First region; 222 Second region; 230 False finger; 300 Reflection grating electrode; 310 Connecting finger bar; 400 Temperature compensation layer; 500 Passivation layer; Z1 First staggered region; Z2 Second staggered region. Detailed implementation manners

[0042] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and should not be construed as a limitation to the present application.

[0043] 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, which integrates low insertion loss and good suppression performance, and has a small volume at the same time. It mainly uses the piezoelectric effect to convert electrical energy and mechanical energy into each other.

[0044] For a conventional SAW device, the surface acoustic wave propagating transversely along the length direction of the finger bar will form a transverse resonance mode on the substrate, that is, the transverse mode appearing in and near the passband. This transverse mode will increase the device loss, cause a large fluctuation in the Q value, and reduce the performance of the SAW device (resonator, filter). Therefore, the prior art suppresses the transverse mode by adding a mass load at the end of the finger bar. For example, a thickened (Piston structure) and / or widened (hammerhead structure) metal end is set at the end of the finger bar, or the electrode finger is tilted and other methods are used to reduce the acoustic velocity in this area. However, the method of adding a suppression load at the end of the finger bar of the electrode finger can achieve a certain transverse mode suppression effect, but 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, the direct treatment of the end of the finger bar will also affect the propagation of the main mode to a certain extent, resulting in a decrease in the Q value.

[0045] Based on the above problems, the present application provides a surface acoustic wave device structure and apparatus, including a substrate and an IDT electrode. By setting each electrode finger of the IDT electrode to include at least a first metal layer and a second metal layer stacked in sequence, and setting the thickness of the first metal layer in the first region to be not less than its thickness in the second region, and utilizing the physical property that the mass density of the first metal layer is greater than that of the second metal layer, the propagation speed of the surface acoustic wave excited by the IDT electrode is shown to be greater in the first region than in the second region. In effect, it is equivalent to adding a suppression load at the extended end of the electrode finger, which can not only suppress the lateral mode and improve the Q value of the surface acoustic wave device, but also greatly reduce the processing technology requirements of the surface acoustic wave device structure and the process cost.

[0046] According to one aspect of the present application, there is provided a surface acoustic wave device structure having a lateral mode suppression effect, as Figures 1 to 12 shown. The device structure includes a substrate 100 and an IDT electrode 200 (Interdigital transducer). For ease of description, the propagation direction of the surface acoustic wave is set as the first direction, i.e., the X direction in the figure, the direction in which the electrode fingers of the IDT electrode 200 extend is set as the second direction, i.e., the Y direction in the figure, and the direction of the stacked thickness of the surface acoustic wave device structure is set as the third direction, i.e., the Z direction in the figure. Among them, the first direction is orthogonal to the second direction and parallel to the surface of the substrate 100, and the third direction is perpendicular to the orthogonal plane of the first direction and the second direction.

[0047] The IDT electrode 200, as the most basic unit constituting the surface acoustic wave device structure, can be composed of a high-density conductive metal or alloy material, including but not limited to being made of one of metals such as titanium, chromium, copper, silver, aluminum, platinum, tungsten, molybdenum or their metal alloys, and can be a single-layer metal film or a stacked metal film stacked with multiple metal layers.

[0048] As Figures 1 to 4 shown, the IDT electrode 200 is formed on the substrate 100 and includes at least a pair of interdigital electrodes arranged oppositely. Each interdigital electrode includes a bus bar 210 extending along the first direction and a plurality of electrode fingers 220 extending along the second direction from one side of the bus bar 210. Among them, each electrode finger 220 at least includes a first metal layer and a second metal layer stacked in the third direction, the second metal layer is located above the first metal layer, and the mass density of the first metal layer is greater than that of the second metal layer. In addition, each electrode finger 220 at least further includes a first region 221 and a second region 222 that are connected in the second direction and have the same thickness, and the thickness of the first metal layer in the first region 221 is not less than its thickness in the second region 222.

[0049] As an example, the electrode finger 220 preferably adopts a stack of metal titanium and aluminum. Among them, the first metal layer is formed on the substrate 100 and is composed of metal titanium, and the second metal layer is formed on the first metal layer and is composed of metal aluminum.

[0050] It can be understood that the surface acoustic wave is a typical elastic wave. By applying an alternating voltage to the IDT electrode 200, the surface acoustic wave device can be excited to form a surface acoustic wave. When the surface acoustic wave propagates in a substance and encounters the interface of different media (with different acoustic propagation speeds), it will reflect the surface acoustic wave in the direction not parallel to the interface, avoiding the formation of resonance of stray waves, and thus playing a role in reducing energy loss.

[0051] Since the impedance relationship of the elastic wave propagating in the medium satisfies Z = ρC, where Z is the acoustic impedance, ρ is the medium density, and C is the acoustic velocity. It can be seen from the formula that the greater the density of the propagation medium, the greater the acoustic impedance, that is, the stronger the resistance encountered by the elastic wave when propagating in the medium.

[0052] Therefore, in this application, by controlling the formation thicknesses of the first metal layer and the second metal layer in the first region 221 and the second region 222 respectively, and making the thickness of the first metal layer in the first region 221 not less than its thickness in the second region 222, using the characteristics that the first metal layer and the second metal layer have different mass densities, the mass per unit area of the electrode finger 220 in the first region 221 and the second region 222 is finely adjusted, so that the surface acoustic waves excited by the IDT electrode 200 can exhibit different propagation speeds in the first region 221 and the second region 222, and then form multiple different sound velocity regions, thereby effectively suppressing the transverse mode of the surface acoustic wave device and avoiding the excitation of transverse mode resonance.

[0053] Since the thickness of the first metal layer in the first region 221 is not less than its thickness in the second region 222, and the mass density of the first metal layer is greater than that of the second metal layer, the surface acoustic wave has a higher acoustic impedance in the first region 221 than in the second region 222. As a result, the propagation speed of the surface acoustic wave in the first region 221 is less than its propagation speed in the second region 222. In this application, by arranging the first region 221 on one side close to the extension end of the electrode finger 220 extending along the second direction, and the second region 222 on one side close to the first region 221, the propagation speed of the surface acoustic wave in the first region 221 of the electrode finger 220 is less than the propagation speed of the surface acoustic wave in the second region 222 of the electrode finger 220. In terms of effect, it is equivalent to adding a suppression load at the extension end of the electrode finger 220. Compared with the prior art of setting a thickened (Piston structure) and / or widened (hammerhead structure) metal suppression load at the extension end of the electrode finger 220, this application can not only suppress the lateral mode and improve the Q value of the surface acoustic wave device, but also greatly reduce the processing difficulty and process cost of the surface acoustic wave device structure.

[0054] In some embodiments, as Figure 2 shown, the thicknesses of the first metal layer in the first region 221 and the second region 222 are different. Among them, the thickness of the first metal layer in the first region 221 is greater than its thickness in the second region 222, and the thickness of the second metal layer in the first region 221 is less than its thickness in the second region 222.

[0055] Since the thickness of the electrode finger 220 on the substrate 100 is the same, thus, when the thickness of the first metal layer in the first region 221 is greater than its thickness in the second region 222, the thickness of the second metal layer in the first region 221 is less than its thickness in the second region 222, and the mass density of the first metal layer is greater than that of the second metal layer, the propagation speed of the surface acoustic wave in the first region 221 of the electrode finger 220 is less than the propagation speed of the surface acoustic wave in the second region 222 of the electrode finger 220. In terms of effect, it is equivalent to adding a suppression load at the extension end of the electrode finger 220.

[0056] In some embodiments, as Figures 3 to 8 shown, the thicknesses of the first metal layer in the first region 221 and the second region 222 are the same, and at least one groove 2201 extending along the second direction is further provided in the second region 222 of the first metal layer. The second metal layer is located on the first metal layer and fills the groove 2201.

[0057] In the present application, at least one groove 2201 extending in the second direction is provided in the second region 222 of each electrode finger 220, so as to change the mass distribution of the electrode finger 220 in the second region 222 by means of the groove 2201, and the vertical projection of the groove 2201 in the third direction is located within the vertical projection plane of the electrode finger 220, such that the surface acoustic wave excited and formed by the IDT electrode 200 can be affected by the groove 2201, and different propagation speeds are exhibited in the region corresponding to the groove 2201 in the second region 222, the region corresponding to the non-groove 2201 in the second region 222, and the first region 221, and multiple different sound velocity regions are formed, thereby effectively suppressing the transverse mode of the surface acoustic wave device and avoiding the excitation of transverse mode resonance.

[0058] Since at least one groove 2201 extending in the second direction is provided on the first metal layer in the second region 222, the density of the surface acoustic wave propagation medium in the region corresponding to the groove 2201 is reduced and the acoustic impedance is decreased, so that the propagation speed of the surface acoustic wave in the region corresponding to the groove 2201 is greater than that in the region corresponding to the non-groove 2201. In the present application, by setting the vertical projection of the groove 2201 within the vertical projection plane of the electrode finger 220, the propagation speed of the surface acoustic wave in the first region 221 of the electrode finger 220 is less than that in the region corresponding to the groove 2201 in the second region 222, and in effect, it is equivalent to increasing the suppression load at the extended end of the electrode finger 220. Compared with the prior art in which a thickened (Piston structure) and / or widened (hammerhead structure) metal suppression load is provided at the extended end of the electrode finger 220, the present application can not only suppress the transverse mode and improve the Q value of the surface acoustic wave device, but also greatly reduce the processing difficulty and process cost of the structure of the surface acoustic wave device.

[0059] Specifically, the region formed by the electrode fingers 220 of different interdigital electrodes extending staggeredly in the first direction can be set as the staggered region, and the staggered region can be further divided into two first staggered regions Z1 and a second staggered region Z2 in the second direction according to the electrode fingers 220, and the second staggered region Z2 is located between the two first staggered regions Z1. Among them, the second staggered region Z2 is the region corresponding to the staggered overlap of any adjacent electrode fingers 220 in the first direction, and is composed of the first region 221 and the second region 222; the first staggered region Z1 is located between the second staggered region Z2 and the two bus bars 210, that is, the region corresponding to the mutual interval between the extended end of the electrode finger 220 and the bus bar 210.

[0060] Since the vertical projection of the groove 2201 in the third direction lies within the vertical projection plane of the electrode finger 220, when the groove 2201 extends along the second direction on the electrode finger 220, the boundary of the groove 2201 on the side close to the extension end of the electrode finger 220 needs to maintain a preset spacing from the extension end of the electrode finger 220 at least. The range of this preset spacing corresponds to the range of the first region 221, and the second region 222 corresponds to the region outside the first region 221 within the second staggered region Z2. Thus, when the surface acoustic wave excited by the IDT electrode 200 propagates in the first direction in the second staggered region Z2, it can be affected by the corresponding region of the groove 2201 and have at least two different propagation speeds in the second staggered region Z2, namely, the first sound velocity region V1 corresponding to the first region 221 and the second sound velocity region V2 corresponding to the corresponding region of the groove 2201 in the second region 222. Moreover, the propagation speed of the surface acoustic wave in the second sound velocity region V2 is greater than that in the first sound velocity region V1, thereby effectively suppressing the transverse mode of the surface acoustic wave device and avoiding the excitation of transverse mode resonance.

[0061] As Figures 5 to 8 shown, a plurality of grooves 2201 can also be provided on the first metal layer of the second region 222 at the same time. The interval between any two adjacent grooves 2201 in the second direction of the plurality of grooves 2201 will correspondingly form a first sound velocity region V1 in the second region 222. Thus, when the surface acoustic wave propagates in the first direction in the second region 222, it can be affected by the corresponding region of the groove 2201 and have at least two different propagation speeds in the second region 222, which further adjusts the sound velocity region distribution of the surface acoustic wave in the second region 222 and improves the transverse mode suppression effect on the surface acoustic wave.

[0062] Since the specific position, specific number, and specific size of the groove 2201 on the first metal layer in the second region 222 will directly affect the mass distribution of the electrode finger 220, and further affect the velocity distribution of the surface acoustic wave in the second region 222. Thus, in order to further improve the transverse mode suppression effect of the surface acoustic wave device structure, the present application can also be adjusted based on the setting position, setting number, and setting size of the groove 2201 on the first metal layer in the second region 222 and any combination of the above conditions, so as to finely adjust the propagation velocity of the surface acoustic wave in the second region 222, so as not to affect the main acoustic mode while suppressing the transverse mode, and also reflect various stray waves to avoid additional energy dissipation, thereby achieving the effect of improving the performance of the surface acoustic wave device. Therefore, the present application does not specifically limit the number and size of the grooves 2201 extending along the second direction on the first metal layer in the second region 222. That is to say, the number of grooves 2201 in the second region 222 provided on each electrode finger 220 can specifically be one groove 2201 extending along the second direction, or multiple grooves 2201 spaced apart from each other in the second direction, and the sizes of the multiple grooves 2201 can be the same or different.

[0063] Among them, the setting size of the groove 2201 on the first metal layer in the second region 222 can specifically include the extension width along the first direction, the extension length along the second direction, and the extension depth along the third direction. Among them, the extension width of the groove 2201 in the first direction should not be greater than the width of the electrode finger 220, and the extension length in the second direction should not be greater than the length of the second region 222, so as to ensure that the vertical projection of the groove 2201 in the third direction can be located within the vertical projection plane of the electrode finger 220. At the same time, the extension depth of the groove 2201 in the third direction should not be greater than the thickness of the first metal layer, so as to ensure that the surface of the substrate 100 will not be damaged during the formation of the groove 2201.

[0064] As an example, the first metal layer can include an opposite first surface and a second surface in the third direction, the second surface is in contact with the substrate 100, and the groove 2201 extends from the first surface of the first metal layer to one side of the second surface until the preset depth is satisfied.

[0065] Since the specific extension depth of the groove 2201 in the third direction can also change the mass distribution of the electrode finger 220 on the substrate 100, it also directly affects the propagation velocity of the surface acoustic wave for different depths of the groove 2201. By controlling the depth of the groove 2201 in the third direction and making it meet the preset depth, the propagation velocity of the surface acoustic wave in the second region 222 can be effectively controlled.

[0066] It should be noted that the above-mentioned electrode finger 220 is only an exemplary illustration of a stacked structure composed of only a first metal layer and a second metal layer. In actual applications, the electrode finger 220 can also be composed of the first metal layer and the second metal layer described in any of the above embodiments stacked periodically in a bottom-up order, and no specific expansion will be carried out here.

[0067] In some embodiments, as Figure 9 shown, each interdigital electrode further includes a plurality of dummy fingers 230. Each dummy finger 230 is correspondingly formed in the first staggered region Z1 and extends along the second direction from one side of the bus bar 210. In the second direction, there should be a gap between the extended ends of each electrode finger 220 of one interdigital electrode and the extended ends of each dummy finger 230 of the other interdigital electrode, and they are in one-to-one correspondence.

[0068] Since the dummy fingers 230 are correspondingly formed in the first staggered region Z1, and each dummy finger 230 is spaced from and in one-to-one correspondence with the extended end of an electrode finger 220, when the surface acoustic wave excited by the IDT electrode 200 propagates along the first direction in the second staggered region Z2, it can be affected by the corresponding region of the dummy fingers 230 and have at least two different propagation speeds in the second staggered region Z2, that is, the third sound velocity region V3 located between the extended ends of the dummy fingers 230 and the extended ends of the electrode fingers 220, and the fourth sound velocity region V4 corresponding to the position of the dummy fingers 230.

[0069] And the propagation speed of the surface acoustic wave in the fourth sound velocity region V4 is greater than that in the third sound velocity region V3, thereby further suppressing the transverse mode of the surface acoustic wave device and improving the Q value of the surface acoustic wave device.

[0070] In addition, as Figure 1 shown, a pair of reflection grating electrodes 300 are also provided on the substrate 100 on both sides of the IDT electrode 200 along the first direction, and the pair of reflection grating electrodes 300 are spaced along the first direction on both sides of the IDT electrode 200. Each reflection grating electrode 300 includes a plurality of connecting finger bars 310 extending along the second direction. At least one first groove (not shown in the figure) extending along the second direction is provided on each connecting finger bar 310, and the vertical projection of the first groove in the third direction is located within the vertical projection plane of the corresponding connecting finger bar 310.

[0071] It should be noted that the first groove formed on the connecting finger bar 310 and the groove 2201 on the electrode finger 220 can be the same or different, and the present application does not make specific limitations on this.

[0072] The above surface acoustic wave device structure can be a common surface acoustic wave device structure, i.e., STD-SAW (Standard Surface Acoustic Wave), or a surface acoustic wave device structure based on a POI (Piezoelectric on Insulator) substrate 100, i.e., POI-SAW, or a temperature-compensated surface acoustic wave device structure, i.e., TC-SAW (Temperature Compensation Surface Acoustic Wave, TC-SAW). The specific type of the surface acoustic wave device structure is not specifically limited in this application.

[0073] As an example, when the above surface acoustic wave device structure is POI-SAW, the substrate 100 may include a piezoelectric substrate, which is a laminated substrate including a piezoelectric material layer 140, such as Figure 10 and Figure 11 shown, the IDT electrode 200 is formed on the piezoelectric material layer 140. Among them, the laminated substrate may be a laminated substrate in which a low acoustic velocity material layer 130 and a piezoelectric material layer 140 are sequentially laminated on a high acoustic velocity substrate layer 110, or a laminated substrate in which a high acoustic velocity material layer 120, a low acoustic velocity material layer 130, and a piezoelectric material layer 140 are sequentially laminated on a high acoustic velocity substrate layer 110.

[0074] Specifically, the piezoelectric material layer 140 includes but is not limited to one of materials such as LiTaO3 (lithium tantalate), LiNbO3 (lithium niobate), quartz, zinc oxide (ZnO), and aluminum nitride (AlN) with various cut types. In this embodiment, the piezoelectric material layer 140 preferably uses lithium niobate or lithium tantalate materials, which have advantages such as excellent piezoelectric effects and electromechanical coupling effects and have been widely used in surface acoustic wave device structures.

[0075] 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 materials such as silicon oxide, glass, silicon oxynitride, tantalum oxide, or a material mainly composed of a compound obtained by adding fluorine, carbon, or boron to silicon oxide. In this embodiment, the low acoustic velocity material layer 130 preferably uses a silicon oxide film (SiOx), such as a SiO2 film.

[0076] The high acoustic velocity material layer 120 is a film layer with a relatively high acoustic velocity, such that the propagation velocity of the surface acoustic wave in the high acoustic velocity material layer 120 is higher than that in the piezoelectric material layer 140. The high acoustic velocity material layer 120 includes, but is not limited to, a medium with one of materials such as silicon nitride, aluminum nitride, zinc oxide, silicon oxynitride, sapphire, and aluminum oxide as the main component. In the present embodiment, the high acoustic velocity material layer 120 is an aluminum nitride film (AlN).

[0077] The high acoustic velocity substrate layer 110 serves as a supporting substrate for the piezoelectric substrate 100 and includes, but is not limited to, one of various piezoelectrics such as aluminum oxide, lithium tantalate, lithium niobate, and quartz, alumina, sapphire, magnesium oxide, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, etc., various ceramics, diamond, glass, etc., semiconductors such as gallium nitride, or resins. In the present embodiment, the high acoustic velocity substrate layer 110 preferably uses a silicon substrate.

[0078] As an example, when the above surface acoustic wave device structure is a TC-SAW, the substrate 100 can be the piezoelectric material layer 140, as Figure 12 shown, the IDT electrode 200 is formed on the piezoelectric material layer 140. Meanwhile, after the IDT electrode 200 is formed on the piezoelectric material layer 140, it further includes forming a temperature compensation layer 400 on the piezoelectric material layer 140 to completely cover the IDT electrode 200, and forming a passivation layer 500 on the temperature compensation layer 400 to cover the upper surface of the temperature compensation layer 400.

[0079] The temperature compensation layer 400 is composed of a material capable of providing a positive temperature coefficient and includes, but is not limited to, a laminated layer of one or a combination of silicon dioxide, germanium dioxide, and silicon oxyfluoride. Since ordinary SAW is susceptible to temperature changes, a temperature compensation material with a positive frequency temperature coefficient can be coated to form a TC-SAW with a temperature compensation function, thereby improving the temperature drift phenomenon.

[0080] The material of the passivation layer 500 is composed of a material with stable properties and includes, but is not limited to, silicon nitride, which is used to protect and isolate the surface of the temperature compensation layer 400.

[0081] According to the second aspect of the present application, a surface acoustic wave device is further provided, and the device includes the surface acoustic wave device structure described in any of the above embodiments.

[0082] To further illustrate the transverse mode suppression effect of the surface acoustic wave device provided in this application, the surface acoustic wave device in this 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 indicate that the resonator or the filter has strong transverse mode ripples, serious passband clutter, and using this surface acoustic wave device will cause deterioration of the overall performance.

[0083] As an example, after comparing the performance of an existing surface acoustic wave device and the surface acoustic wave device of this application when applied to a resonator, the comparison results are as Figure 13 and Figure 14 shown, where Figure 13 is the performance graph of a resonator applying the structure of an ordinary surface wave device without transverse mode suppression effect, Figure 14 is the performance graph of a resonator applying the surface wave device structure of this application. According to the comparison of Figure 13 and Figure 14 , it can be seen that Figure 14 the admittance curves are smoother, and compared with the admittance curve in Figure 13 , the number of parasitic resonance peaks in the admittance curve in Figure 14 is almost invisible, which also indicates that the surface wave device structure provided in this application can effectively suppress the transverse mode in the resonator, can further improve the Q value of the resonator or the filter, and the performance of the resonator or the filter can be significantly improved.

[0084] It should be noted that according to the surface acoustic wave device structure and device with transverse mode suppression effect in any of the above embodiments disclosed in this article, it can also be provided 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 orientation data units, global positioning system (GPS) devices, mobile phones, cellular phones, smart phones, session initiation protocol (SIP) phones, tablet computers, phablets, servers, computers, portable computers, mobile computing devices, wearable computing devices (such as 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, unmanned aerial vehicles, and multi-rotor aircraft.

[0085] In summary, the present application provides a surface acoustic wave device structure and apparatus with a transverse mode suppression effect, including a substrate 100 and an IDT electrode 200 formed on the substrate 100. The IDT electrode 200 includes two interdigital electrodes arranged oppositely, and each interdigital electrode includes a bus bar 210 and a plurality of electrodes. The electrode fingers 220 of different interdigital electrodes are arranged staggeredly and spaced apart. By setting the thickness of each electrode finger 220 of the IDT electrode to be not less than its thickness in the second region 222, and utilizing the physical property that the mass density of the first metal layer is greater than that of the second metal layer, the propagation speed of the surface acoustic wave excited by the IDT electrode 200 shows that the propagation speed in the first region 221 is not lower than that in the second region 222. In terms of effect, it is equivalent to increasing the suppression load at the extended end of the electrode finger 220, which can not only achieve the effect of suppressing the transverse mode and improve the Q value of the surface acoustic wave device, but also greatly reduce the processing technology requirements of the surface acoustic wave device structure and the process cost.

[0086] In the description of the foregoing 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 connection with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0087] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

Claims

1. A surface acoustic wave device structure, characterized in that: include: substrate; The IDT electrode comprises at least a pair of interdigital electrodes disposed opposite to each other on the substrate; each of the interdigital electrodes comprises a bus bar extending along a first direction, and a plurality of electrode fingers extending from one end of the bus bar along a second direction, and the electrode fingers of different interdigital electrodes are alternately arranged in sequence in the first direction; Each of the electrode fingers includes at least a first metal layer and a second metal layer stacked in a third direction, the second metal layer is located on the first metal layer, and the mass density of the first metal layer is greater than that of the second metal layer; each of the electrode fingers also includes at least a first region and a second region connected in the second direction and having the same thickness, the thickness of the first metal layer in the first region is not less than its thickness in the second region; the second direction is orthogonal to the first direction, and the third direction is perpendicular to the orthogonal plane of the first direction and the second direction.

2. The surface acoustic wave device structure according to claim 1, characterized in that: The thickness of the first metal layer in the first region is greater than the thickness in the second region, and the thickness of the second metal layer in the first region is less than the thickness in the second region.

3. The surface acoustic wave device structure according to claim 1, characterized in that: The thickness of the first metal layer in the first area is the same as that in the second area, and the first metal layer has at least one groove extending along the second direction in the second area. The second metal layer is located on the first metal layer and fills the groove.

4. The surface acoustic wave device structure according to claim 3, characterized in that: An extension width of the groove in the first direction is not greater than a line width of the electrode finger, and in the third direction, a vertical projection of the groove is located in the second region.

5. The surface acoustic wave device structure according to claim 3, characterized in that: The first metal layer includes a first surface and a second surface opposite to each other in the third direction, the second surface is in contact with the substrate, and the groove extends from the first surface to a side of the second surface by a preset depth.

6. The surface acoustic wave device structure according to claim 5, characterized in that: A preset depth of the groove extending from the first surface to one side of the second surface is not greater than a thickness of the first metal layer.

7. The surface acoustic wave device structure according to claim 3, characterized in that: A plurality of grooves are disposed on the first metal layer in the second region, and the plurality of grooves are sequentially spaced apart along the second direction.

8. The surface acoustic wave device structure according to claim 3, characterized in that: A central axis of each electrode finger along the second direction overlaps with a central axis of a groove corresponding to the second region along the second direction.

9. The surface acoustic wave device structure according to claims 1 to 8, characterized in that: The electrode finger includes a stack of a plurality of the first metal layers and the second metal layers.

10. The surface acoustic wave device structure according to claim 1, characterized in that: Each of the interdigitated electrodes also includes a plurality of dummy fingers, which extend from one side of the bus bar along the second direction and are alternately arranged in sequence between the adjacent electrode fingers in the first direction. In the second direction, the extension end of each of the dummy fingers is spaced apart from and corresponds one-to-one to the extension end of an electrode finger.

11. The surface acoustic wave device structure according to claim 1, characterized in that: The surface acoustic wave device structure 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.

12. The surface acoustic wave device structure according to claim 11, characterized in that: Each of the reflective gate electrodes includes a plurality of connecting fingers extending along the second direction, each of the connecting fingers is provided with at least one first groove extending along the second direction, and a vertical projection of the first groove in the third direction is located within a vertical projection plane corresponding to the connecting finger.

13. A surface acoustic wave device, characterized in that: The surface acoustic wave device comprises the surface acoustic wave device structure according to any one of claims 1 to 12.

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