Thin-film surface acoustic wave resonator, and filter

Abstract

Disclosed in the present invention are a thin-film surface acoustic wave resonator, and a filter. The resonator may comprise a piezoelectric substrate, and an interdigital transducer arranged on a surface of the piezoelectric substrate, wherein the interdigital transducer comprises two metal busbars arranged opposite each other; a plurality of interdigital electrodes which are of an interdigital shape and are alternately arranged at intervals in a first direction are arranged between the two metal busbars; one end of each interdigital electrode is a free end, and the other end thereof is connected to a metal busbar; the area where the plurality of interdigital electrodes overlap in the first direction is an effective excitation area; and at least one mass block is provided on each interdigital electrode, the mass block extends in the lengthwise direction of each interdigital electrode, the mass block is at least located in the effective excitation area, and the width of the mass block gradually changes in a preset manner. The present invention can suppress a lateral mode response of a device, increase Q values of an acoustic resonator and an acoustic filter, and can reduce the insertion loss of the acoustic filter.

Description

Thin film surface acoustic wave resonator and filter TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor devices, and more particularly, to a thin film surface acoustic wave resonator and filter. BACKGROUND

[0002] Acoustic filter technology is a key technology in the 5G era. In order to adapt to new requirements, acoustic filters need to have lower insertion loss. By suppressing the spurious response of acoustic resonators or filters and improving the Q value, the insertion loss of the filter can be well reduced.

[0003] TF-SAW (Thin Film Surface Acoustic Wave) devices are widely used in the radio frequency field due to their ultra-high Q value, but compared with traditional SAW devices, TF-SAW devices will excite more spurious modes, which will affect the insertion loss of acoustic devices. Among them, the suppression of transverse modes is a problem that attracts much attention in the design process of TF-SAW devices.

[0004] In previous studies, a variety of structures for suppressing transverse modes have been derived, among which the PistonMode structure and the variable electrode structure are the most widely used. The basic principle of the PistonMode structure is to change the wave speed at both ends of the acoustic channel by increasing the metal rate at the end region of the IDT or applying a mass block above it. The acoustic wave is reflected by the discontinuity of the sound speed and the appropriate reflection amplitude and phase are obtained to achieve the purpose of suppressing the transverse mode. The basic principle of the variable electrode structure is basically the same as that of the PistonMode structure, and the difference is that it changes the sound speed in different regions by changing the metal rate of each part of the IDT.

[0005] However, both of the above-mentioned structures have shortcomings. Among them, the PistonMode structure has poor flexibility and small sound speed adjustment range, and it is easy to introduce new spurious when a larger sound speed difference is obtained. The sound speed adjustment of the variable electrode structure is controlled by the metal rate of the IDT, and changing the metal rate has a significant impact on the excitation efficiency, resonance frequency and other indicators of the whole device. SUMMARY

[0006] The purpose of the present application is to provide a thin film surface acoustic wave resonator and filter, which can suppress the transverse mode response of the device, reduce the insertion loss of the acoustic filter, and improve the Q value of the acoustic resonator and filter.

[0007] To achieve the above purpose, in a first aspect, the present application provides a thin film surface acoustic wave resonator, comprising:

[0008] a piezoelectric substrate;

[0009] An interdigital transducer is disposed on a surface of the piezoelectric substrate.

[0010] The interdigital transducer comprises:

[0011] Two metal bus bars are oppositely arranged, and the metal bus bars extend along a first direction. A plurality of interdigital electrodes are arranged in an interdigital manner and alternately arranged along the first direction between the two metal bus bars. The interdigital electrodes extend along a second direction perpendicular to the first direction. One end of the interdigital electrodes is a free end, and the other end of the interdigital electrodes is connected to the metal bus bar. The area where the plurality of interdigital electrodes overlap in the first direction is an effective excitation area.

[0012] A mass is arranged on the interdigital electrode and extends along the second direction and has a set shape. At least part of the mass is located in the effective excitation area and covers part of the surface of the interdigital electrode. In the second direction, the width of the mass gradually changes in a preset manner. The mass as a whole has a symmetry axis in the first direction and the second direction, respectively. Optionally, one end of the mass is located at the free end of the interdigital electrode, and the other end of the mass extends to the boundary of the effective excitation area along the second direction.

[0013] Alternatively, one end of the mass is located at the free end of the interdigital electrode, and the other end of the mass extends to the boundary of the effective excitation area along the second direction.

[0014] Alternatively, both ends of the mass are located within the boundary of the effective excitation area.

[0015] Optionally, the width of the two ends of the mass is greater than the width of the central region of the mass.

[0016] Optionally, the width of the two ends of the mass is less than or equal to the width of the interdigital electrode, and the width of the mass gradually changes from wide to narrow from the two ends of the mass to the center of the mass.

[0017] Optionally, the width of the two ends of the mass is less than the width of the central region of the mass.

[0018] Optionally, the width of the central region of the mass is less than or equal to the width of the interdigital electrode, and the width of the mass gradually changes from narrow to wide from the two ends of the mass to the center of the mass.

[0019] Optionally, a plurality of hollow windows are arranged on the mass and spaced apart from each other from one end of the mass to the other end of the mass, and the hollow windows expose the surface of the interdigital electrode.

[0020] Optionally, a plurality of interval regions are arranged along one end of the mass block to the other end of the mass block, the interval regions expose the surface of the interdigital electrode, and the plurality of interval regions separate the mass block into a plurality of sub-mass blocks distributed along the second direction.

[0021] Optionally, the mass block arranged on the interdigital electrode is one or more layers.

[0022] When the mass block is multiple layers, the materials of the layers are the same or different, and the shapes of the layers are the same or different.

[0023] Optionally, the material of the mass block is a metal material or a non-metal material, the metal material includes at least one of gold, silver, aluminum, copper, tungsten, titanium, chromium, platinum, molybdenum, or an alloy of the above metals, and the non-metal material includes at least one of silicon, silicon dioxide, polysilicon, silicon nitride, silicon oxynitride, silicon carbide, aluminum oxide, zinc oxide, and titanium oxide.

[0024] Optionally, one or more intermediate medium layers are arranged between the mass block and the interdigital electrode.

[0025] When the plurality of intermediate medium layers are arranged, the materials of the intermediate medium layers are the same or different.

[0026] Optionally, the material of the intermediate medium layer is a metal material or a non-metal material, the metal material includes at least one of gold, silver, aluminum, copper, and tungsten, and the non-metal material includes at least one of silicon, silicon dioxide, and polysilicon.

[0027] Optionally, the width and length of the mass block on any two adjacent interdigital electrodes in the interdigital transducer gradually change in the same way.

[0028] Optionally, the width and length of the mass block on any two adjacent interdigital electrodes in the interdigital transducer gradually change in the same way.

[0029] Alternatively, the width and length of the mass block on any two adjacent interdigital electrodes in the interdigital transducer gradually change in different ways.

[0030] Optionally, the piezoelectric substrate includes a substrate layer, a capture layer, a low sound speed layer, and a piezoelectric layer stacked in turn from bottom to top, and the mass block is arranged on the surface of the piezoelectric layer.

[0031] In a second aspect, the application provides a thin film type surface acoustic wave filter, including the thin film type surface acoustic wave resonator of any one of the first aspect.

[0032] The application has the following beneficial effects:

[0033] The thin film type surface acoustic wave resonator of the present application sets a mass block on the interdigital transducer interdigital electrode surface, the mass block is located in the effective excitation area of the interdigital electrode and extends along the length direction of the interdigital electrode, the wave speed distribution of the surface acoustic wave in the interdigital transducer can be changed by increasing the mass block on the interdigital electrode, through the difference of the wave speed, on the one hand, the amplitude and phase of the reflected wave can be adjusted, when the appropriate reflected amplitude and phase are reached, the transverse parasitic response of the device is suppressed; on the other hand, because the wave speed of the covered area of the mass block is smaller than that of the uncovered area, the surface acoustic wave can be reflected back to the effective excitation area more, the transverse leakage of the surface acoustic wave is reduced, therefore the Q value of the acoustic resonator and filter can be improved, and the insertion loss of the acoustic filter is reduced. Further, compared with the existing PistonMode structure interdigital transducer, the mass block arranged on the interdigital transducer in the present application can be designed in a plurality of different shapes, by changing the shape of the upper layer mass block of the interdigital transducer, the sound speed of each area of the interdigital transducer can be controlled as needed, so that the sound wave is limited in the effective excitation area of the interdigital transducer, and then the range of sound speed adjustment can be increased, the design flexibility is improved, and the interdigital transducer structure can be applied to a variety of interdigital transducers.

[0034] Further, compared with the existing variable electrode type structure interdigital transducer, the present application does not change the metal rate of the interdigital electrode, reduces the influence on the excitation efficiency and working frequency of the device, and is more suitable for the design of the device.

[0035] The system of the present application has other characteristics and advantages, which will be apparent from and / or set forth in the accompanying drawings and the following detailed description, which together serve to explain certain principles of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0036] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout and in which:

[0037] Fig. 1a shows a top view of a thin film type surface acoustic wave resonator according to an embodiment of the present application.

[0038] Fig. 1b shows a cross-sectional view along A-A' in Fig. 1a.

[0039] Fig. 1c shows a conductance and admittance curve diagram of an original surface acoustic wave resonator.

[0040] Fig. 1d shows a conductance and admittance curve diagram of a surface acoustic wave resonator according to an embodiment of the present application.

[0041] Figure 1e shows a Q value curve comparison between a raw surface acoustic wave resonator and the surface acoustic wave resonator of embodiment 1.

[0042] Figure 2a shows a top view of a thin film surface acoustic wave resonator of embodiment 2 of the present application.

[0043] Figure 2b shows a cross-sectional view along A-A' in Figure 2a.

[0044] Figure 3 shows a top view of a thin film surface acoustic wave resonator of embodiment 3 of the present application.

[0045] Figure 4 shows a top view of a thin film surface acoustic wave resonator of embodiment 4 of the present application.

[0046] Figure 5 shows a top view of a thin film surface acoustic wave resonator of embodiment 5 of the present application.

[0047] Figure 6 shows a top view of a thin film surface acoustic wave resonator of embodiment 6 of the present application.

[0048] Figure 7 shows a top view of a thin film surface acoustic wave resonator of embodiment 7 of the present application.

[0049] Figure 8 shows a top view of a thin film surface acoustic wave resonator of embodiment 8 of the present application.

[0050] Figure 9 shows a top view of a thin film surface acoustic wave resonator of embodiment 9 of the present application.

[0051] Figure 10a shows a top view of a thin film surface acoustic wave resonator of embodiment 10 of the present application.

[0052] Figure 10b shows a top view of another thin film surface acoustic wave resonator of embodiment 10 of the present application.

[0053] Figure 11 shows a top view of a thin film surface acoustic wave resonator of embodiment 12 of the present application. DETAILED DESCRIPTION

[0054] To solve the defects of the IDT (interdigital transducer) structure design in the existing TF-SAW, the present application controls the shape change of the mass block above the IDT (including the effective excitation area in the center of the IDT), the material selection, and the superposition of the multi-layer mass block, which can effectively control the sound speed in each area, is conducive to the suppression of the transverse mode, so that the present design can be flexibly used in the design of acoustic devices; on the other hand, the present design does not change the metal rate of the IDT, which reduces the influence on the excitation efficiency and working frequency of the device, and is more suitable for the design of the device.

[0055] The application will be described in greater detail with reference to the drawings. Although the preferred embodiments of the application are shown in the drawings, it is understood that the application can be carried out in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0056] The thin film type surface acoustic wave resonator of the present application mainly suppresses the transverse mode by designing various shapes of layered mass blocks on the interdigital transducer. The shape of the mass block on the interdigital transducer can be changed according to the design needs of the resonator. The shape of the mass block can be continuous or discontinuous, and can not only be gradually changed from wide to narrow or from narrow to wide, but also periodically or non-periodically changed in width. The setting range of the mass block above the interdigital transducer is not limited to the aperture area, and can also include the aperture area and extend into the metal bus area. Meanwhile, the shape of the mass block on adjacent interdigital transducers can be the same or different. The mass block can be one layer or multiple layers, and the material used in each layer is not limited, and the shape of each layer can be consistent or inconsistent. In addition, the mass block can be directly applied above the interdigital transducer, or can be separated from the interdigital transducer by an intermediate medium layer. The design of the interdigital transducer structure of the present application can improve the flexibility of the design, and at the same time, due to the more obvious difference in sound velocity, the sound wave is more limited in the effective excitation area of the interdigital transducer, reducing energy leakage, and thus achieving the effect of improving the Q value.

[0057] In order to better illustrate the scheme of the present application, the present application will be explained and described in more detail through the following embodiments.

[0058] Embodiment 1

[0059] As shown in FIG. 1a and FIG. 1b, the present embodiment provides a thin film type surface acoustic wave resonator, comprising: a piezoelectric substrate and an interdigital transducer arranged on the surface of the piezoelectric substrate.

[0060] Referring to FIG. 1b, in the present embodiment, the piezoelectric substrate comprises, from bottom to top, a substrate layer 108, a trapping layer 107, a low sound velocity layer 106 and a piezoelectric layer 101, and the mass block 104 is arranged on the surface of the piezoelectric layer 101.

[0061] Referring to FIG. 1a, in the present embodiment, the interdigital transducer comprises:

[0062] Two metal bus bars 102 are oppositely arranged, the metal bus bars 102 extend along a first direction, and a plurality of interdigital electrodes 103 are alternately and spacedly arranged along the first direction between the two metal bus bars 102 in an interdigital manner; the interdigital electrodes 103 extend along a second direction perpendicular to the first direction, one end of the interdigital electrodes 103 is a free end, and the other end of the interdigital electrodes 103 is connected with the metal bus bars 102, and the area where the plurality of interdigital electrodes 103 overlap in the first direction is an effective excitation area; optionally, the interdigital transducer further comprises a false toe 105.

[0063] In the interdigital transducer (including the metal bus bars 102 and the plurality of interdigital electrodes 103), the material is metal, including at least one of gold, silver, aluminum, copper, and tungsten.

[0064] The interdigital electrodes 103 are provided with a mass block 104 extending along the second direction, the mass block 104 is located in the effective excitation area, along the second direction, the width of the mass block 104 gradually changes in a preset manner, the mass block 104 has a symmetry axis in the first direction and the second direction respectively, and the mass block 104 is used to change the wave velocity distribution and thereby suppress the response of the transverse mode.

[0065] In the preset manner, the following optional width gradient manners are included:

[0066] (1) along the second direction, the width of the mass block 104 gradually changes from wide to narrow from one end to the central area and then gradually changes from narrow to wide to the other end;

[0067] (2) along the second direction, the width of the mass block 104 gradually changes from narrow to wide from one end to the central area and then gradually changes from wide to narrow to the other end;

[0068] (3) along the second direction, the width of the mass block 104 periodically changes from wide to narrow from one end to the other end.

[0069] (4) along the second direction, the width of the mass block 104 non-periodically changes from wide to narrow from one end to the other end.

[0070] In each of the above gradient manners, the width change can be linear or curved, and each of the gradient manners needs to ensure that the overall shape of the mass block 104 has a symmetry axis in the first direction and the second direction. In the specific implementation process, the width gradient manner of the mass block can be flexibly selected according to actual needs.

[0071] In the embodiment, one end of the mass 104 is located at the free end of the interdigital electrode 103, and the other end of the mass 104 extends to the boundary of the effective excitation region in the second direction. Meanwhile, the width of the two ends of the mass 104 is greater than the width of the central region of the mass 104; the width of the two ends of the mass 104 is equal to the width of the interdigital electrode 103, and the width of the mass 104 gradually changes from wide to narrow from the two ends of the mass 104 to the center of the mass 104.

[0072] Specifically, as shown in FIG. 1a, the mass 104 is arranged on the surface of the interdigital electrode 103 and is located in the effective excitation region. The mass 104 continuously extends from the free end of the interdigital electrode 103 to the boundary of the effective excitation region at the other end of the interdigital electrode 103, that is, the length of the mass 104 is the same as the length of the interdigital electrode 103 in the effective excitation region. Meanwhile, the width of the two ends of the mass 104 is equal to the width of the interdigital electrode 103, and the width of the two ends of the mass 104 is greater than the width of the central region of the mass 104. From one end of the mass 104 to the center of the mass 104, the width of the mass 104 gradually changes from wide to narrow. From the center of the mass 104 to the other end of the mass 104, the width of the mass 104 gradually changes from narrow to wide. The edges of the mass 104 are continuous and gradually change in a curve.

[0073] The mass 104 in the embodiment is a layer. The mass 104 can be formed by a deposition process, that is, the mass 104 is composed of a continuous semiconductor film layer, and the thickness of the mass 104 can be selected according to the specific parameters of the device. The material of the mass 104 can be a metal material or a non-metal material. The metal material includes at least one of gold, silver, aluminum, copper, tungsten, titanium, chromium, platinum, molybdenum, or an alloy of the above metals. The non-metal material includes at least one of silicon, silicon dioxide, polysilicon, silicon nitride, silicon oxynitride, silicon carbide, aluminum oxide, zinc oxide, and titanium oxide.

[0074] In the embodiment, the shapes of the masses 104 on any two adjacent interdigital electrodes 103 in the interdigital transducer are the same.

[0075] The IDT structure design in the embodiment can form a low sound speed region on the mass 104 on the interdigital electrode 103, change the wave speed distribution, suppress the transverse parasitic response, form a more obvious sound speed difference between the mass 104 and the interdigital electrode 103, and more restrict the sound wave in the effective excitation region of the IDT, reduce the transverse leakage of energy, and thus achieve the effect of improving the Q value. Meanwhile, the metal rate of the IDT is not changed in the scheme, which effectively reduces the influence on the excitation efficiency and the working frequency of the device.

[0076] Figure 1c is a curve of admittance and conductance of the original surface acoustic wave resonator (without the mass 104), figure 1d is a curve of admittance and conductance of the surface acoustic wave resonator with the mass 104 according to the embodiment, and figure 1e is a comparison of Q values of the two (in figures 1c-1e, red represents the relevant curve of the original structure, and blue represents the relevant curve of the structure according to the embodiment). As can be seen from the comparison of figures 1c and 1d, the resonator according to the embodiment has a very obvious effect on transverse mode suppression. In addition, as can be seen from figure 1e, the IDT structure design according to the embodiment also has a very obvious effect on the improvement of Q value in a frequency range slightly higher than the resonant frequency.

[0077] Embodiment 2

[0078] As shown in figures 2a and 2b, on the basis of embodiment 1, an intermediate dielectric layer 109 is arranged between the mass 104 and the interdigital electrode 103 in the embodiment. The intermediate dielectric layer 109 can be one layer or multiple layers, and when multiple intermediate dielectric layers 109 are arranged, the materials of the intermediate dielectric layers 109 can be the same or different. The material of the intermediate dielectric layer 109 is a metal material or a non-metal material, the metal material includes at least one of gold, silver, aluminum, copper and tungsten, and the non-metal material includes at least one of silicon, silicon dioxide, polysilicon and silicon nitride. The material of each layer is any combination of the above materials.

[0079] Preferably, the intermediate dielectric layer 109 covers the surface of the interdigital electrode 103, and the metal mass 104 is arranged on the surface of the intermediate dielectric layer 109 on the interdigital electrode 103. The intermediate dielectric layer 109 can change the electrical and / or acoustic properties of the IDT, and has a certain adjusting effect on the performance of the acoustic device, and can also provide protection for the IDT during the manufacture of the mass 104.

[0080] In addition, the design of additionally arranging an intermediate dielectric layer between the mass and the interdigital electrode in the embodiment is also applicable to subsequent embodiments.

[0081] Embodiment 3

[0082] As shown in figure 3, the difference between the embodiment and embodiments 1 or 2 is that the width of the mass 104 gradually changes in a straight line in the embodiment, that is, the width of the mass 104 at both ends is equal to the width of the interdigital electrode 103, the width of the mass 104 gradually narrows from one end of the mass 104 to the center of the mass 104, the width of the mass 104 gradually widens from the center of the mass 104 to the other end of the mass 104, and the shape of the edges of the mass 104 is in the shape of a broken line. The shape of the mass 104 in the embodiment can achieve the same effect of transverse mode suppression as in embodiment 1.

[0083] Embodiment 4

[0084] As shown in FIG. 4, the difference between the present embodiment and embodiment 1 is that one end of the mass 104 in the present embodiment is located at the free end of the interdigital electrode 103, and the other end of the mass 104 extends to outside the boundary of the effective excitation region in the second direction.

[0085] Specifically, the shape of the mass 104 above the interdigital electrode 103 in the present embodiment is the same as that in embodiment 1, i.e., a curved shape gradually changing from wide at both ends to narrow in the middle, but the difference is that part of the mass 104 is arranged on the interdigital electrode 103 within the effective excitation region, and the other part extends to the interdigital electrode 103 outside the effective excitation region, i.e., the length of the mass 104 exceeds the range of the effective excitation region. The structure of the mass 104 in the present embodiment can also achieve the effect of suppressing the transverse mode.

[0086] Embodiment 5

[0087] As shown in FIG. 5, the difference between the present embodiment and the above embodiments is that both ends of the mass 104 are located within the boundary of the effective excitation region, i.e., the length of the mass 104 in the second direction is less than the length of the effective excitation region in the second direction.

[0088] Specifically, the shape of the mass 104 above the interdigital electrode 103 in the present embodiment is the same as that in embodiment 1, i.e., a curved shape gradually changing from wide at both ends to narrow in the middle, but the difference is that both ends of the mass 104 are located within the boundary of the effective excitation region, i.e., the length of the mass 104 is less than the length of the interdigital electrode 103 within the range of the effective excitation region. The structure of the mass 104 in the present embodiment can also achieve the effect of suppressing the transverse mode.

[0089] Embodiment 6

[0090] As shown in FIG. 6, on the basis of embodiment 1, the overall shape of the mass 104 in the present embodiment is the same as that in embodiment 1, i.e., a curved shape gradually changing from wide at both ends to narrow in the middle, but the mass 104 is provided with a plurality of spaced hollow regions.

[0091] Specifically, a plurality of hollow windows are arranged on the mass 104 at equal intervals from one end of the mass 104 to the other end of the mass 104, and the hollow windows expose the surface of the interdigital electrode 103. By arranging the hollow regions, the range and variation form of the sound speed difference in the covered area of the mass 104 can be adjusted, the degree of freedom of design is increased, and the design of suppressing the transverse parasitic response and reducing the transverse energy leakage can be more flexible.

[0092] In addition, the mass with different shapes in embodiments 2-5 can also adopt the structure design of the hollow window in the present embodiment.

[0093] Embodiment 7

[0094] As shown in FIG. 7, on the basis of Embodiment 1, the overall shape of the mass 104 on the interdigital electrode 103 in this embodiment is the same as that of Embodiment 1, both being a curved shape gradually changing from wide at the ends to narrow in the middle, but the mass 104 is composed of a plurality of spaced sub-masses 104.

[0095] Specifically, a plurality of spaced regions are provided along one end of the mass 104 to the other end of the mass 104, the spaced regions exposing the surface of the interdigital electrode 103, and the plurality of spaced regions separate the mass into a plurality of sub-masses 104 spaced along the second direction.

[0096] The structure of the mass 104 in this embodiment can also achieve the effect of suppressing the transverse mode.

[0097] In addition, the mass with different gradual change modes in Embodiments 2-5 can also adopt the structure design of a plurality of spaced sub-masses.

[0098] Embodiment 8

[0099] The difference between this embodiment and Embodiments 1-7 described above is that in this embodiment, the shapes of the masses 104 on any two adjacent interdigital electrodes 103 in the interdigital transducer are the same but the lengths are different.

[0100] Specifically, the width gradual change modes of the masses 104 on any two adjacent interdigital electrodes 103 in the IDT are the same but the lengths are different, and the two adjacent masses 104 can be a combination of any two different shapes of masses 104 in the above (or subsequent) embodiments. For example, as shown in FIG. 8, of the two masses 104 on the two adjacent interdigital electrodes 103, one mass 104 has the shape of the shorter length mass 104 in Embodiment 5, and the other has the shape of the longer length mass 104 in Embodiment 4. The structure of the mass 104 in this embodiment can also achieve the effect of suppressing the transverse mode.

[0101] Embodiment 9

[0102] Similar to Embodiment 8, the difference between this embodiment and Embodiments 1-7 described above is that in this embodiment, the width gradual change modes of the masses 104 on any two adjacent interdigital electrodes 103 in the interdigital transducer are different but the lengths are the same.

[0103] As shown in FIG. 9, in this embodiment, the shape of one of the two adjacent mass blocks 104 is that the width of the central region of the mass block 104 is less than or equal to the width of the interdigital electrode 103, and along the two ends of the mass block 104 to the center of the mass block 104, the width of the mass block 104 is periodically or non-periodically widened from narrow to wide. The shape of the other mass block 104 adopts the shape of the mass block 104 in Embodiment 1. That is, one of the mass blocks 104 is in the shape of narrow at both ends and wide in the middle, and the other is in the shape of wide at both ends and narrow in the middle.

[0104] In other embodiments, all the mass blocks 104 on the IDT can also adopt the shape of the mass block 104 which is narrow at both ends and wide in the middle.

[0105] Embodiment 10

[0106] The difference between this embodiment and the above-mentioned embodiments is that in this embodiment, the shape of the mass block 104 on the IDT is that the width of the two ends of the mass block 104 is less than the width of the interdigital electrode 103, and along the two ends of the mass block 104 to the center of the mass block 104, the width of the mass block 104 is non-periodically widened from wide to narrow.

[0107] As shown in FIG. 10a, the width of the two ends of the mass block 104 is wide as a whole, and the end portions on both sides form outwardly expanded circular arc shapes, and the central region on both sides forms inwardly narrowed circular arc shapes.

[0108] As shown in FIG. 10b, the two sides of the mass block 104 are gradually inwardly narrowed circular arc shapes, and the regions near the two ends have outwardly protruding circular arc regions on both sides.

[0109] Embodiment 11

[0110] As shown in FIG. 11, the difference between this embodiment and the above-mentioned embodiments is that in this embodiment, based on the shape of the mass block 104 shown in FIG. 10b in Embodiment 10, a plurality of spaced hollow windows are added to the mass block 104 in combination with the scheme of Embodiment 6, and the hollow windows expose the underlying piezoelectric layer 101.

[0111] Embodiment 12

[0112] The difference between this embodiment and the above-mentioned embodiments is that in this embodiment, the mass block 104 on the IDT can be multi-layered, and the shape of each layer of mass blocks 104 can be the same or different, and the shape of each layer of mass blocks 104 can be the shape of any of the above-mentioned embodiments.

[0113] Those skilled in the art should understand that the above embodiments are only for better understanding of the present application, and various shapes of the mass in the above embodiments can be adjusted or combined according to the design requirements of the device, and the protection scope of the present application is not limited to the structures of the above embodiments. Simple modifications and improvements of the structure also belong to the protection scope of the present application.

[0114] Embodiment 13

[0115] The embodiment provides a thin film type surface acoustic wave filter, comprising the thin film type surface acoustic wave resonator in any of the above embodiments.

[0116] The above has described the embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A thin-film surface acoustic wave resonator, characterized in that, include: Piezoelectric substrate; Interdigitated transducers are disposed on the surface of the piezoelectric substrate; The interdigital transducer includes: Two metal busbars are arranged opposite each other, the metal busbars extend along a first direction, and a plurality of interdigitated electrodes are provided between the two metal busbars in an interdigitated shape and alternately spaced along the first direction; the interdigitated electrodes extend along a second direction perpendicular to the first direction, one end of the interdigitated electrodes is a free end, and the other end of the interdigitated electrodes is connected to the metal busbars; the area where the plurality of interdigitated electrodes overlap in the first direction is an effective excitation area; The interdigitated electrode is provided with a mass block extending along the second direction. The mass block is located at least within the effective excitation region and covers a portion of the surface of the interdigitated electrode. The width of the mass block gradually changes in a preset manner along the second direction. The mass block as a whole has an axis of symmetry in the first direction and the second direction, respectively.

2. The thin-film surface acoustic wave resonator according to claim 1, characterized in that, One end of the mass block is located at the free end of the interdigitated electrode, and the other end of the mass block extends along the second direction to the boundary of the effective excitation region; Alternatively, one end of the mass block is located at the free end of the interdigitated electrode, and the other end of the mass block extends along the second direction beyond the boundary of the effective excitation region; Alternatively, both ends of the mass block are located within the boundary of the effective excitation region.

3. The thin-film surface acoustic wave resonator according to claim 2, characterized in that, The width at both ends of the mass block is greater than the width of the central region of the mass block.

4. The thin-film surface acoustic wave resonator according to claim 3, characterized in that, The width at both ends of the mass block is less than or equal to the width of the interdigitated electrodes. From both ends of the mass block to the center of the mass block, the width of the mass block changes from wide to narrow periodically or non-periodically.

5. The thin-film surface acoustic wave resonator according to claim 2, characterized in that, The width at both ends of the mass block is smaller than the width of the central region of the mass block.

6. The thin-film surface acoustic wave resonator according to claim 5, characterized in that, The width of the central region of the mass block is less than or equal to the width of the interdigitated electrode. From both ends of the mass block to the center of the mass block, the width of the mass block changes from narrow to wide periodically or non-periodically.

7. The thin-film surface acoustic wave resonator according to claim 4 or 6, characterized in that, Along one end of the mass block to the other end, the mass block is provided with a plurality of hollowed-out windows at intervals, the hollowed-out windows exposing the surface of the interdigitated electrodes.

8. The thin-film surface acoustic wave resonator according to claim 4 or 6, characterized in that, A plurality of spaced regions are provided along one end of the mass block to the other end of the mass block, the spaced regions exposing the surface of the interdigitated electrode, and the plurality of spaced regions dividing the mass block into a plurality of sub-mass blocks spaced apart along the second direction.

9. The thin-film surface acoustic wave resonator according to claim 1, characterized in that, The mass block disposed on the interdigitated electrode is one or more layers; When the mass block is multi-layered, the materials of each layer of mass block may be the same or different, and the shapes of each layer of mass block may be the same or different.

10. The thin-film surface acoustic wave resonator according to any one of claims 1-6 and 9, characterized in that, The mass block is made of metallic or non-metallic materials. The metallic materials include alloys of at least one or more of the following metals: gold, silver, aluminum, copper, tungsten, titanium, chromium, platinum, and molybdenum. The non-metallic materials include at least one of the following: silicon, silicon dioxide, polycrystalline silicon, silicon nitride, silicon oxynitride, silicon carbide, aluminum oxide, zinc oxide, and titanium oxide.

11. The thin-film surface acoustic wave resonator according to claim 1, characterized in that, One or more intermediate dielectric layers are provided between the mass block and the interdigitated electrode; When multiple intermediate dielectric layers are set, the materials of each intermediate dielectric layer may be the same or different; 12. The thin-film surface acoustic wave resonator according to claim 11, characterized in that, The intermediate dielectric layer is made of a metallic or non-metallic material. The metallic material includes at least one of gold, silver, aluminum, copper, and tungsten, and the non-metallic material includes at least one of silicon, silicon dioxide, polycrystalline silicon, and silicon nitride.

13. The thin-film surface acoustic wave resonator according to claim 1, characterized in that, The width gradient and length of the mass blocks on any two adjacent interdigital electrodes in the interdigital transducer are the same.

14. The thin-film surface acoustic wave resonator according to claim 1, characterized in that, The width gradient of the mass blocks on any two adjacent interdigital electrodes in the interdigital transducer is the same, but the lengths are different. Alternatively, the width gradient of the mass blocks on any two adjacent interdigital electrodes in the interdigital transducer may differ, but their lengths may be the same.

15. The thin-film surface acoustic wave resonator according to claim 1, characterized in that, The piezoelectric substrate includes a base layer, a trapping layer, a low-velocity layer and a piezoelectric layer stacked at least sequentially from bottom to top, and the mass block is disposed on the surface of the piezoelectric layer.

16. A thin-film surface acoustic wave filter, characterized in that, Includes the thin-film surface acoustic wave resonator as described in any one of claims 1-15.

Images