Surface acoustic wave filter, filter bank, multiplexer and radio frequency module

Abstract

Provided in the present disclosure are a surface acoustic wave filter, a filter bank, a multiplexer and a radio frequency module, wherein the surface acoustic wave filter comprises: a substrate, a wafer, a resonator, wafer bonding pads, bumps and a sealing member. Substrate bonding pads are provided on a top surface of the substrate; the wafer comprises a supporting substrate and a piezoelectric film, the piezoelectric film being directly or indirectly arranged on the supporting substrate; the wafer has a first surface, a second surface, and a side wall perpendicular to the first surface and connecting the first surface to the second surface; a concave contour is provided between the side wall and the first surface of the wafer, and in a direction from the second surface to the first surface, the distance between the concave contour and the center of the wafer gradually reduces; the resonator and the wafer bonding pads are provided on the first surface of the wafer, and by means of the bumps, the substrate bonding pads are electrically connected to the wafer bonding pads in a manner of corresponding to each other on a one-to-one basis; and the sealing member wraps the wafer and is connected to the substrate, so that the wafer, wafer bonding pads, bumps, substrate bonding pads and substrate enclose a cavity structure. The surface acoustic wave filter has high sensitivity and good reliability.

Description

Surface acoustic wave filters and groups, multiplexers and RF modules

[0001] Cross-references

[0002] This disclosure claims priority to Chinese patent publication No. 202310780494.9, filed on June 29, 2023, entitled “Surface Acoustic Wave Filter and Group, Multiplexer and Radio Frequency Module,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the field of semiconductor technology, and in particular to a surface acoustic wave filter. Background Art

[0004] With the emergence and development of 5G communications, the frequency requirements for surface acoustic wave filters are becoming increasingly higher, requiring them to reach frequencies up to 5G. Existing surface acoustic wave filters made of lithium niobate or lithium tantalate materials only have a center frequency of around 3.5G. Furthermore, as the frequency of surface acoustic wave filters increases, the impact of distributed capacitance, inductance, and packaging structure on their performance increases. The insertion loss of higher-frequency surface acoustic wave filters also gradually increases, resulting in reduced sensitivity in communication equipment using surface acoustic wave filters.

[0005] The market is increasingly demanding higher levels of integration for communication devices. RF modules require integrating filtering components with non-filtering components for different functions within a single module. The bare die of these filtering components is typically made of brittle single crystal material. When packaged with non-filtering chips, these components are susceptible to processing stress, leading to cracking and edge collapse of the filter die, which in turn reduces the reliability of the surface acoustic wave filter.

[0006] Public content

[0007] According to one aspect of the present disclosure, a surface acoustic wave filter is provided, comprising a substrate, a wafer, at least one resonator, a plurality of wafer pads, a plurality of bumps, and a sealing member. The top surface of the substrate has a plurality of substrate pads. The wafer includes a supporting substrate and a piezoelectric film, the piezoelectric film being directly or indirectly disposed on the supporting substrate such that the wafer has a first surface, a second surface disposed opposite the first surface, and a sidewall disposed perpendicular to the first surface, the sidewall connecting the first and second surfaces. A concave profile is formed between the sidewall of the wafer and the first surface, with the distance between the concave profile and the center of the wafer gradually decreasing from the second surface toward the first surface. At least one resonator is disposed on the first surface of the wafer. A plurality of wafer pads are disposed on the first surface of the wafer and are located outside the resonator. A plurality of bumps electrically connect the plurality of substrate pads to the plurality of wafer pads in a one-to-one correspondence. A sealing member covers the wafer and is connected to the substrate, such that the wafer, wafer pads, the plurality of bumps, the substrate pads, and the substrate form a cavity structure.

[0008] According to one embodiment of the present disclosure, a low acoustic velocity layer is further provided between the support substrate and the piezoelectric film, and the velocity of the bulk wave propagating in the low acoustic velocity layer is lower than the velocity of the bulk wave propagating in the piezoelectric film.

[0009] According to one embodiment of the present disclosure, the low acoustic velocity layer includes at least one of SiO2, fluorine-doped silicon oxide, Al2O3, AlN, Si3N4, SiON, Ta2O5, silicon boride, and glass.

[0010] According to one embodiment of the present disclosure, a high acoustic velocity layer is further provided between the low acoustic velocity layer and the supporting substrate, and the velocity of the bulk wave propagating in the high acoustic velocity layer is greater than the velocity of the bulk wave propagating in the piezoelectric film.

[0011] According to one embodiment of the present disclosure, the high acoustic velocity layer is a dielectric material selected from at least one of polycrystalline silicon, Poly-Si, amorphous silicon, and AlN.

[0012] According to one embodiment of the present disclosure, the piezoelectric film includes at least one of LiTaO 3 , LiNbO 3 , ZnO, AlN or PZT.

[0013] According to one embodiment of the present disclosure, the material of the support substrate is at least one selected from SiC, SiN, Si, glass, quartz, AlN, sapphire, and ceramics.

[0014] According to one embodiment of the present disclosure, the distance between the first surface of the wafer and the surface of the support substrate close to the piezoelectric film is less than or equal to 2λ', where λ' is the wavelength of the acoustic wave determined by the electrode period of the resonator.

[0015] According to one embodiment of the present disclosure, the average film thickness of the resonator and the wavelength of the acoustic wave to which the surface acoustic wave filter responds satisfy 8%≤H / λ≤13%, where H is the average film thickness of the resonator and λ is the wavelength of the acoustic wave to which the surface acoustic wave filter responds.

[0016] According to one embodiment of the present disclosure, the resonator is an IDT, and the average duty cycle of the IDT is W / (W+G), where W is the width of each of the multiple electrode fingers of the IDT, and G is the spacing width between the multiple electrode fingers and adjacent electrode fingers. The average duty cycle is greater than or equal to 0.5 and less than or equal to 0.7.

[0017] According to one embodiment of the present disclosure, on a plane perpendicular to the length direction of the concave profile, a transition fillet is formed between the concave profile and the sidewall, and the radius of the transition fillet is 1 μm-70 μm.

[0018] According to an embodiment of the present disclosure, the concave profile intersects the first surface at a first intersection line, and a distance between the first intersection line and the sidewall is 5 μm-30 μm.

[0019] According to an embodiment of the present disclosure, the concave profile intersects the sidewall at a second intersection line, and a distance between the second intersection line and the first surface is 1 μm-80 μm.

[0020] According to one embodiment of the present disclosure, on a plane perpendicular to the length direction of the concave profile, the concave profile is linear, and an inner angle formed by the concave profile and the side wall is 90°-150°.

[0021] According to an embodiment of the present disclosure, on a plane perpendicular to the length direction of the concave profile, the concave profile is in an arc shape or an ellipse shape, and the concave profile is a continuous concave curve.

[0022] According to one embodiment of the present disclosure, on a plane perpendicular to the length direction of the concave profile, the concave profile includes a first sub-profile and a second sub-profile, the first sub-profile intersects the sidewall, and the second sub-profile intersects the first surface.

[0023] According to one embodiment of the present disclosure, the first sub-contour intersects with the second sub-contour at a third intersection line, and the slope of the tangent surface of the first sub-contour at the third intersection line is equal to the slope of the tangent surface of the second sub-contour at the third intersection line.

[0024] According to one embodiment of the present disclosure, on a plane perpendicular to the length direction of the concave contour, a third sub-contour is further arranged between the first sub-contour and the second sub-contour, the third sub-contour intersects with the first sub-contour at a fourth intersection line, and the tangent slope of the first sub-contour at the fourth intersection line is equal to the tangent slope of the third sub-contour at the fourth intersection line; the third sub-contour intersects with the second sub-contour at a fifth intersection line, and the tangent slope of the second sub-contour at the fifth intersection line is equal to the tangent slope of the third sub-contour at the fifth intersection line.

[0025] According to an embodiment of the present disclosure, the third sub-contour includes a plurality of adjacently arranged fourth sub-contours, and the tangent slopes of the adjacently arranged fourth sub-contours at respective adjacent intersection lines are equal.

[0026] According to another aspect of the present disclosure, a surface acoustic wave filter group is provided, wherein at least one surface acoustic wave filter adopts the surface acoustic wave filter described above.

[0027] According to a third aspect of the present disclosure, a multiplexer is provided, comprising a transmitting end and a receiving end, wherein at least one of the receiving end and / or the transmitting end comprises at least one surface acoustic wave filter, and the surface acoustic wave filter adopts the surface acoustic wave filter described above.

[0028] According to a fourth aspect of the present disclosure, a radio frequency module is provided, comprising at least one or more of a power amplifier, a low noise amplifier, a switch, an antenna, and a surface acoustic wave filter, wherein the surface acoustic wave filter adopts the surface acoustic wave filter described above.

[0029] From the above technical solutions, it can be seen that the advantages and positive effects of the surface acoustic wave filter proposed in this disclosure are:

[0030] The surface acoustic wave filter proposed in the present disclosure includes a substrate, a wafer, at least one resonator, a plurality of wafer pads, a plurality of bumps and a seal. The top surface of the substrate has a plurality of substrate pads. The wafer includes a supporting substrate and a piezoelectric film, and the piezoelectric film is directly or indirectly arranged on the supporting substrate, so that the wafer has a first surface, a second surface arranged opposite to the first surface, and a side wall arranged perpendicular to the first surface, and the side wall connects the first surface and the second surface. There is a concave profile between the side wall of the wafer and the first surface, and the distance between the concave profile and the center of the wafer gradually decreases along the direction from the second surface to the first surface. The setting of the concave profile can achieve the dispersion of processing stress, reduce the cracking or edge collapse of the filter wafer, and improve the reliability of the entire surface acoustic wave filter.

[0031] At least one resonator is disposed on the first surface of the wafer. A plurality of wafer pads are disposed on the first surface of the wafer and are located outside the resonator. A plurality of bumps electrically connect the plurality of substrate pads to the plurality of wafer pads in a one-to-one correspondence. A sealant covers the wafer and is connected to the substrate, such that the wafer, wafer pads, the plurality of bumps, the substrate pads, and the substrate form a cavity structure. The integrally encapsulated sealant is beneficial for reducing the insertion loss of the surface acoustic wave filter and improving the sensitivity of the surface acoustic wave filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and other features and advantages of the present disclosure will become more apparent by describing in detail example embodiments thereof with reference to the accompanying drawings.

[0033] FIG1 is a schematic structural diagram of a surface acoustic wave filter according to the present disclosure.

[0034] FIG. 2 is a schematic diagram of a second embodiment of the surface acoustic wave filter of the present disclosure.

[0035] FIG3 is a schematic diagram of a third embodiment of the surface acoustic wave filter of the present disclosure.

[0036] FIG. 4 is a schematic diagram of a fourth embodiment of the surface acoustic wave filter of the present disclosure.

[0037] FIG5 is a schematic diagram of a fifth embodiment of the surface acoustic wave filter of the present disclosure.

[0038] FIG6 is a schematic diagram of a sixth embodiment of the surface acoustic wave filter of the present disclosure.

[0039] FIG. 7 is a schematic diagram of a seventh embodiment of the surface acoustic wave filter of the present disclosure.

[0040] 10. The reference numerals are as follows: 100 - surface acoustic wave filter; 101 - substrate; 1011 - substrate pad; 102 - wafer; 1021 - supporting substrate; 1022 - piezoelectric film; 1023 - first surface; 1024 - second surface; 1025 - sidewall; 103 - concave profile; 1031 - first sub-profile; 1032 - second sub-profile; 1033 - third sub-profile; 1034 - fourth sub-profile; 104 - resonator; 105 - wafer pad; 106 - bump; 107 - sealing member; 201 - low acoustic velocity layer; 301 - high acoustic velocity layer; 401 - first intersection line; 402 - second intersection line; 501 - third intersection line; 601 - fourth intersection line; 602 - fifth intersection line; d1 - the distance between the first intersection line and the side wall; d2 - the distance between the second intersection line and the first surface; α - the internal angle formed by the concave profile and the side wall. DETAILED DESCRIPTION

[0041] Typical embodiments that embody the features and advantages of the present disclosure will be described in detail in the following description. It should be understood that the present disclosure can have various variations in different embodiments without departing from the scope of the present disclosure, and the description and drawings therein are essentially for illustrative purposes rather than for limiting the present disclosure.

[0042] In the following description of different exemplary embodiments of the present disclosure, reference is made to the accompanying drawings, which form a part of this disclosure and in which are shown by way of example different exemplary structures, systems and steps that may implement aspects of the present disclosure. It should be understood that other specific schemes of components, structures, exemplary devices, systems and steps may be used, and structural and functional modifications may be made without departing from the scope of the present disclosure. Moreover, although the terms "upper", "middle", "inner", etc. may be used in this specification to describe different exemplary features and elements of the present disclosure, these terms are used herein for convenience only, for example, according to the orientation of the examples depicted in the accompanying drawings. Nothing in this specification should be construed as requiring a specific three-dimensional orientation of a structure to fall within the scope of the present disclosure.

[0043] In order to make the above-mentioned objects, features and advantages of the present disclosure clear and easy to understand, specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0044] As shown in FIG1 , the surface acoustic wave filter 100 of the present disclosure includes a substrate 101, a wafer 102, at least one resonator 104, a plurality of wafer bonding pads 105, a plurality of bumps 106, and a sealing member 107. The top surface of the substrate 101 has a plurality of substrate bonding pads 1011. The wafer 102 includes a supporting substrate 1021 and a piezoelectric film 1022. The piezoelectric film 1022 is directly or indirectly disposed on the supporting substrate 1021, such that the wafer 102 has a first surface 1023, a second surface 1024 disposed opposite to the first surface 1023, and a sidewall 1025 disposed perpendicular to the first surface 1023, connecting the first surface 1023 and the second surface 1024. A concave profile 103 is defined between the sidewall 1025 and the first surface 1023 of the wafer 102. The distance between the concave profile 103 and the center of the wafer 102 gradually decreases as it moves from the second surface 1024 toward the first surface 1023. At least one resonator 104 is disposed on the first surface 1023 of the wafer 102. A plurality of wafer bonding pads 105 are disposed on the first surface 1023 of the wafer 102 and are located outside the resonator 104. A plurality of bumps 106 electrically connect the plurality of substrate bonding pads 1011 to the plurality of wafer bonding pads 105 in a one-to-one correspondence. A sealing member 107 encloses the wafer 102 and is connected to the substrate 101, such that the wafer 102, the wafer bonding pads 105, the plurality of bumps 106, the substrate bonding pads 1011, and the substrate 101 form a cavity structure.

[0045] The present disclosure utilizes an integrally packaged seal to reduce insertion loss and improve the sensitivity of the SAW filter. The concave profile disperses processing stress, reduces cracking or chipping of the filter wafer, and improves the reliability of the entire SAW filter.

[0046] As shown in FIG2 , in the second embodiment of the surface acoustic wave filter 100 of the present disclosure, a low-acoustic-velocity layer 201 is further provided between the supporting substrate 1021 of the wafer 102 and the piezoelectric thin film 1022. The velocity of the bulk waves propagating through the low-acoustic-velocity layer 201 is lower than the velocity of the bulk waves propagating through the piezoelectric thin film 1022. The provision of the low-acoustic-velocity layer between the supporting substrate and the piezoelectric thin film, and the lower velocity of the bulk waves propagating through the piezoelectric thin film, can reduce leakage of surface acoustic waves into the supporting substrate, reduce insertion loss, and improve the Q value of the surface acoustic wave filter.

[0047] In this embodiment, the low acoustic velocity layer 201 includes at least one of SiO2, fluorine-doped silicon oxide, Al2O3, AlN, Si3N4, SiON, Ta2O5, borosilicate, and glass. Among the above components, the low acoustic velocity layer is preferably a polycrystalline structure rather than a single crystal structure. The grain boundary defects of the polycrystalline structure can enhance the reflection ability of the surface acoustic wave, reduce the leakage of the surface acoustic wave to the supporting substrate, reduce the insertion loss, and improve the quality factor of the surface acoustic wave filter. The low acoustic velocity layer can also be composed of a mixture of the above substances or a mixture mainly composed of the above substances. The low acoustic velocity layer can be prepared by processes such as chemical vapor deposition, physical vapor deposition, sputtering, atomic layer deposition, molecular epitaxial growth, organic silicon compound coating / firing, thermal oxidation, etc. In order to enhance the density of the low acoustic velocity layer, it can be sintered by high temperature heat treatment, such as heat treatment at 600-1000°C. The low acoustic velocity layer can reduce the processing stress between the piezoelectric film and the supporting substrate, thereby reducing the occurrence of cracks and peeling. Preferably, the thickness of the low acoustic velocity layer is set to be less than 20μm.

[0048] As shown in Figure 3, in the third embodiment of the surface acoustic wave filter 100 of the present disclosure, a high acoustic velocity layer 301 is further disposed between the low acoustic velocity layer 201 and the supporting substrate 1021. The bulk wave propagating through the high acoustic velocity layer 301 has a higher acoustic velocity than the bulk wave propagating through the piezoelectric thin film 1022. The high acoustic velocity layer can enhance the bonding strength between the low acoustic velocity layer and the supporting substrate, trap charge in the surface acoustic wave filter, reduce leakage of surface acoustic waves into the supporting substrate, reduce insertion loss, and improve the quality factor of the surface acoustic wave device.

[0049] In this embodiment, the high acoustic velocity layer 301 is a dielectric material selected from at least one of polycrystalline silicon, poly-Si, amorphous silicon, and AlN. This material selection allows the high acoustic velocity layer to utilize a polycrystalline or amorphous structure rich in structural traps, which can capture charge in the surface acoustic wave filter, reduce leakage of surface acoustic waves to the supporting substrate, and reduce insertion loss.

[0050] In other embodiments, a waveguide layer may be further provided between the piezoelectric film and the low acoustic velocity layer to further enhance the quality factor of the surface acoustic wave device.

[0051] In other embodiments, a dielectric layer, a temperature compensation layer, etc. may be provided on the surface of the piezoelectric film away from the supporting substrate. This reduces the possibility of interfacial delamination between the supporting substrate and the piezoelectric film, and reduces the possibility of cracks or gaps in the piezoelectric film during subsequent processing steps.

[0052] As shown in FIG4 , in the fourth embodiment of the surface acoustic wave filter 100 of the present disclosure, the concave profile 103 intersects the first surface 1023 at a first intersection line 401. The distance d1 between the first intersection line 401 and the sidewall 1025 is 5 μm to 30 μm. This distance ensures the strength of the filter device wafer while achieving good stress dispersion.

[0053] In this embodiment, the concave profile 103 intersects the sidewall 1025 at the second intersection line 402. The distance d2 between the second intersection line 402 and the first surface 1023 is 1 μm-80 μm. This distance can ensure the strength of the filter device wafer while achieving a good stress dispersion effect.

[0054] In this embodiment, the concave profile 103 is linear in a plane perpendicular to the length of the concave profile 103, and the internal angle α formed between the concave profile 103 and the sidewall 1025 is between 90° and 150°. The linear concave profile is easy to machine, and the internal angle α between the concave profile and the sidewall of 90° and 150° ensures sufficient material between the concave profile and the sidewall, ensuring the strength of the connection.

[0055] In other embodiments, in a plane perpendicular to the length of the concave profile 103, the concave profile 103 is arc-shaped or elliptical, and the concave profile 103 is a continuous concave curve. Using an arc-shaped or elliptical concave profile simplifies processing, ensures processing reliability, and better distributes stress during packaging. Using a concave profile that is a continuous concave curve simplifies processing, eliminates unevenness, and better distributes stress during packaging.

[0056] As shown in Figure 5, in the fifth embodiment of the surface acoustic wave filter 100 of the present disclosure, the concave profile 103 includes a first sub-profile 1031 and a second sub-profile 1032 on a plane perpendicular to the length direction of the concave profile 103. The first sub-profile 1031 intersects with the sidewall 1025, and the second sub-profile 1032 intersects with the first surface 1023. The use of two sub-profiles to form the concave profile simplifies and ensures reliable processing. Furthermore, the two sub-profiles can better disperse stress during packaging.

[0057] In this embodiment, the first sub-contour 1031 and the second sub-contour 1032 intersect at the third intersection line 501. The slope of the section of the first sub-contour 1031 at the third intersection line 501 is equal to the slope of the section of the second sub-contour 1032 at the third intersection line 501. This equalization of the slope of the section of the first sub-contour at the third intersection line and the slope of the section of the second sub-contour at the third intersection line enables a smooth transition between the two sub-contours, reduces cracking or chipping of the filter wafer, and improves the reliability of the entire surface acoustic wave filter.

[0058] As shown in Figure 6, in the sixth embodiment of the surface acoustic wave filter 100 of the present invention, on a plane perpendicular to the length direction of the concave contour 103, a third sub-contour 1033 is further arranged between the first sub-contour 1031 and the second sub-contour 1032, and the third sub-contour 1033 intersects with the first sub-contour 1031 at the fourth intersection 601, and the sectional slope of the first sub-contour 1031 at the fourth intersection 601 is equal to the sectional slope of the third sub-contour 1033 at the fourth intersection 601; the third sub-contour 1033 intersects with the second sub-contour 1032 at the fifth intersection 602, and the sectional slope of the second sub-contour 1032 at the fifth intersection 602 is equal to the sectional slope of the third sub-contour 1033 at the fifth intersection 602. A third sub-contour is set between the two sub-contours, and the section slope of the first sub-contour at the fourth intersection is set to be equal to the section slope of the third sub-contour at the fourth intersection, and the section slope of the second sub-contour at the fifth intersection is set to be equal to the section slope of the third sub-contour at the fifth intersection. This can achieve a smooth transition of multiple sub-contours, reduce the cracking or edge collapse of the filter wafer, and improve the reliability of the entire surface acoustic wave filter.

[0059] As shown in FIG7 , in the seventh embodiment of the surface acoustic wave filter 100 of the present disclosure, the third sub-contour 1033 includes multiple adjacent fourth sub-contours 1034, and the cut surface slopes of the adjacent fourth sub-contours 1034 at their respective adjacent intersections are equal. Further subdividing the third sub-contour into multiple fourth sub-contours, and ensuring that the cut surface slopes of the adjacent fourth sub-contours at their respective adjacent intersections are equal, further achieves a smooth transition of the concave profile, reduces filter wafer cracking or edge collapse, and improves the reliability of the entire surface acoustic wave filter.

[0060] In the above embodiment, a transition fillet is formed between the concave profile 103 and the sidewall 1025 on a plane perpendicular to the length direction of the concave profile 103, with a transition fillet radius of 1 μm-70 μm. The provision of the transition fillet facilitates a smooth transition between the sidewall and the concave profile, further preventing edge collapse and other phenomena.

[0061] In the above embodiment, the resonator 104 is an IDT, which includes N input electrode fingers and M output electrode fingers, wherein M and N are positive integers greater than or equal to 1, and M and N may be the same or different. The input electrode fingers and the output electrode fingers are alternately arranged along a certain direction. Reflectors may be provided on both sides of the IDT, wherein the IDT and the reflector may be provided in the same plane to simplify the surface acoustic wave device preparation process. The average duty cycle of the IDT is W / (W+G), wherein W is the width of each of the multiple electrode fingers of the IDT, and G is the spacing width between the multiple electrode fingers and adjacent electrode fingers, and the average duty cycle is greater than or equal to 0.5 and less than or equal to 0.7.

[0062] In the above embodiment, the average film thickness of the resonator 104 and the wavelength of the acoustic wave to which the SAW filter 100 responds satisfy the relationship 8% ≤ H / λ ≤ 13%, where H is the average film thickness of the resonator 104 and λ is the wavelength of the acoustic wave to which the SAW filter 100 responds. This can suppress the frequency offset of the SAW filter, thereby reducing insertion loss on the high-frequency side within the passband.

[0063] In the above embodiment, the distance between the first surface 1023 of the wafer 102 and the surface of the support substrate 1021 proximal to the piezoelectric film 1022 is less than or equal to 2λ', where λ' is the wavelength of the acoustic wave determined by the electrode period of the resonator 104. This allows for easy adjustment of the mechanical coupling coefficient. Furthermore, the thickness of the piezoelectric film can be selected to be between 0.5λ' and 2λ'.

[0064] Furthermore, the thickness of the chip pad is greater than the thickness of the resonator to reduce the risk of damage to the piezoelectric film in the subsequent bump formation process.

[0065] In the above embodiments, the material of the support substrate 1021 is at least one selected from SiC, SiN, Si, glass, quartz, AlN, sapphire, and ceramics.

[0066] In the above embodiments, the piezoelectric film 1022 includes at least one of LiTaO 3 , LiNbO 3 , ZnO, AlN, or PZT.

[0067] It should be noted that in a two-layer structure (where the supporting substrate and the piezoelectric film are in direct contact), the supporting substrate is a high-acoustic-velocity substrate, where the speed of sound propagating through the high-acoustic-velocity substrate is greater than the speed of sound propagating through the piezoelectric film. Preferably, the linear expansion coefficients of the supporting substrate and the piezoelectric film differ by no more than 10%. More preferably, the supporting substrate is a single-crystal Si substrate or sapphire substrate. The piezoelectric film is preferably a single-crystal piezoelectric film.

[0068] It should be noted that the surface acoustic wave filters shown in the drawings and described in this specification are only a few examples of the many surface acoustic wave filters that can employ the principles of the present disclosure. It should be clearly understood that the principles of the present disclosure are in no way limited to any detail or any component of the surface acoustic wave filters shown in the drawings or described in this specification.

[0069] The present disclosure also provides a surface acoustic wave filter group, wherein at least one surface acoustic wave filter adopts the above-mentioned surface acoustic wave filter 100. The surface acoustic wave filter group composed of the above-mentioned surface acoustic wave filters has high sensitivity and high reliability.

[0070] The present disclosure also provides a multiplexer including a transmitter and a receiver, wherein at least one of the transmitter and / or receiver includes at least one surface acoustic wave filter, which employs the aforementioned surface acoustic wave filter 100. A multiplexer constructed using the aforementioned surface acoustic wave filter has high sensitivity and reliability.

[0071] The present disclosure also provides a radio frequency module comprising at least one or more of a power amplifier, a low-noise amplifier, a switch, an antenna, and a surface acoustic wave filter, wherein the surface acoustic wave filter is the aforementioned surface acoustic wave filter 100. The radio frequency module comprising the aforementioned surface acoustic wave filter has high sensitivity and reliability.

[0072] In summary, the surface acoustic wave filter proposed in the present disclosure includes a substrate, a wafer, at least one resonator, a plurality of wafer pads, a plurality of bumps, and a sealing member.

[0073] The top surface of the substrate has a plurality of substrate pads. The wafer includes a supporting substrate and a piezoelectric film, and the piezoelectric film is directly or indirectly arranged on the supporting substrate, so that the wafer has a first surface, a second surface arranged opposite to the first surface, and a side wall arranged perpendicular to the first surface, and the side wall connects the first surface and the second surface. There is a concave profile between the side wall of the wafer and the first surface, and the distance between the concave profile and the center of the wafer gradually decreases along the direction from the second surface to the first surface. The setting of the concave profile can disperse processing stress, reduce cracking or edge collapse of the filter wafer, and improve the reliability of the entire surface acoustic wave filter.

[0074] At least one resonator is disposed on the first surface of the wafer. A plurality of wafer pads are disposed on the first surface of the wafer and are located outside the resonator. A plurality of bumps electrically connect the plurality of substrate pads to the plurality of wafer pads in a one-to-one correspondence. A sealant covers the wafer and is connected to the substrate, such that the wafer, wafer pads, the plurality of bumps, the substrate pads, and the substrate form a cavity structure. The integrally encapsulated sealant is beneficial for reducing the insertion loss of the surface acoustic wave filter and improving the sensitivity of the surface acoustic wave filter.

[0075] The surface acoustic wave filter group proposed in the present disclosure, wherein at least one surface acoustic wave filter adopts the above-mentioned surface acoustic wave filter, has high sensitivity and high reliability.

[0076] The multiplexer proposed in the present disclosure includes a transmitting end and a receiving end, wherein at least one of the receiving end and / or the transmitting end includes at least one surface acoustic wave filter, and the surface acoustic wave filter adopts the above-mentioned surface acoustic wave filter. It has high sensitivity and high reliability.

[0077] The radio frequency module proposed in the present disclosure includes at least one or more of a power amplifier, a low noise amplifier, a switch, an antenna, and a surface acoustic wave filter, wherein the surface acoustic wave filter adopts the above-mentioned surface acoustic wave filter. The radio frequency module composed of the above-mentioned surface acoustic wave filter has high sensitivity and high reliability.

[0078] The above describes and / or illustrates in detail exemplary embodiments of the surface acoustic wave filter and group, multiplexer and radio frequency module proposed in the present disclosure. However, the embodiments of the present disclosure are not limited to the specific embodiments described herein. On the contrary, the components and / or steps of each embodiment can be used independently and separately from the other components and / or steps described herein. Each component and / or each step of an embodiment can also be used in combination with other components and / or steps of other embodiments. When introducing the elements / components / etc. described and / or illustrated herein, the terms "one", "first", "second" and "above" are used to indicate the presence of one or more elements / components / etc. The terms "comprising", "including" and "having" are used to express an open-ended inclusive meaning and mean that in addition to the listed elements / components / etc., there may be additional elements / components / etc.

[0079] The embodiments of the present disclosure are not limited to the specific embodiments described herein, but rather, the components of each embodiment may be used independently and separately from the other components described herein. Each component of an embodiment may also be used in combination with other components of other embodiments. In the description of this specification, the description of the terms "one embodiment", "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0080] The above are merely optional embodiments of the disclosed embodiments and are not intended to limit the disclosed embodiments. Those skilled in the art will readily appreciate that the disclosed embodiments may be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the disclosed embodiments shall be included within the scope of protection of the disclosed embodiments.

Claims

1. A surface acoustic wave filter, characterized in that: include: A substrate having a plurality of substrate pads on a top surface; A wafer, the wafer comprising a supporting substrate and a piezoelectric film, the piezoelectric film being directly or indirectly disposed on the supporting substrate, so that the wafer has a first surface, a second surface disposed opposite to the first surface, and a side wall disposed perpendicular to the first surface, the side wall connecting the first surface and the second surface, characterized in that: A concave profile is provided between the side wall of the wafer and the first surface, and a distance between the concave profile and the center of the wafer gradually decreases in a direction from the second surface to the first surface; At least one resonator is disposed on the first surface of the wafer; A plurality of wafer pads are disposed on the first surface of the wafer and are located outside the resonator; A plurality of bumps electrically connect the plurality of substrate pads to the plurality of wafer pads in a one-to-one correspondence; A sealing member, the sealing member covers the wafer and is connected to the substrate, so that the wafer, the wafer pad, the plurality of bumps, the substrate pad and the substrate form a cavity structure; On a plane perpendicular to the length direction of the concave profile, the concave profile is an arc or an ellipse, and the concave profile is a curve of a continuous concave shape; the concave profile includes a first sub-profile and a second sub-profile, the first sub-profile intersects with the side wall, and the second sub-profile intersects with the first surface.

2. The surface acoustic wave filter according to claim 1, characterized in that A low acoustic velocity layer is further provided between the support substrate and the piezoelectric film, and the acoustic velocity of the body wave propagating in the low acoustic velocity layer is lower than the acoustic velocity of the body wave propagating in the piezoelectric film.

3. The surface acoustic wave filter according to claim 2, characterized in that: The low acoustic velocity layer includes at least one of SiO2, fluorine-doped silicon oxide, Al2O3, AlN, Si3N4, SiON, Ta2O5, silicon boride, and glass.

4. The surface acoustic wave filter according to claim 2 or 3, characterized in that: A high sound velocity layer is further arranged between the low sound velocity layer and the supporting substrate, and the sound velocity of the bulk wave propagating in the high sound velocity layer is greater than the sound velocity of the bulk wave propagating in the piezoelectric film.

5. The surface acoustic wave filter according to claim 4, characterized in that: The high acoustic velocity layer is a dielectric material selected from at least one of polysilicon, Poly-Si, amorphous silicon, and AlN.

6. The surface acoustic wave filter according to claim 1, characterized in that The piezoelectric film includes at least one of LiTaO3, LiNbO3, ZnO, AlN or PZT.

7. The surface acoustic wave filter according to claim 1, characterized in that: The material of the support substrate is at least one selected from SiC, SiN, Si, glass, quartz, AlN, sapphire, and ceramics.

8. The surface acoustic wave filter according to claim 1, wherein: The distance between the first surface of the wafer and the surface of the support substrate close to the piezoelectric film is less than or equal to 2λ', wherein λ' is the wavelength of the sound wave determined by the electrode period of the resonator.

9. The surface acoustic wave filter according to claim 1, wherein: The average film thickness of the resonator and the wavelength of the sound wave to which the surface acoustic wave filter responds satisfy 8%≤H / λ≤13%, wherein H is the average film thickness of the resonator and λ is the wavelength of the sound wave to which the surface acoustic wave filter responds.

10. The surface acoustic wave filter according to claim 1, wherein: The resonator is an IDT, and the average duty cycle of the IDT is W / (W+G), wherein W is the width of each of the multiple electrode fingers of the IDT, and G is the spacing width between the multiple electrode fingers and adjacent electrode fingers, and the average duty cycle is greater than or equal to 0.5 and less than or equal to 0.

7.

11. The surface acoustic wave filter according to claim 1, wherein: On a plane perpendicular to the length direction of the concave profile, a transition fillet is formed between the concave profile and the side wall, and the radius of the transition fillet is 1 μm-70 μm.

12. The surface acoustic wave filter according to claim 1, wherein: The concave profile intersects the first surface at a first intersection line, and a distance between the first intersection line and the side wall is 5 μm-30 μm.

13. The surface acoustic wave filter according to claim 1, wherein: The concave profile intersects the side wall at a second intersection line, and a distance between the second intersection line and the first surface is 1 μm-80 μm.

14. The surface acoustic wave filter according to claim 1, characterized in that The first sub-contour intersects with the second sub-contour at a third intersection line, and a tangent slope of the first sub-contour at the third intersection line is equal to a tangent slope of the second sub-contour at the third intersection line.

15. The surface acoustic wave filter according to claim 1, characterized in that: On a plane perpendicular to the length direction of the concave contour, a third sub-contour is also arranged between the first sub-contour and the second sub-contour, the third sub-contour intersects with the first sub-contour at a fourth intersection line, and the tangent slope of the first sub-contour at the fourth intersection line is equal to the tangent slope of the third sub-contour at the fourth intersection line; the third sub-contour intersects with the second sub-contour at a fifth intersection line, and the tangent slope of the second sub-contour at the fifth intersection line is equal to the tangent slope of the third sub-contour at the fifth intersection line.

16. The surface acoustic wave filter according to claim 15, characterized in that The third sub-contour includes a plurality of adjacently arranged fourth sub-contours, and the tangent slopes of the adjacently arranged fourth sub-contours at respective adjacent intersection lines are equal.

17. A surface acoustic wave filter bank, characterized in that: At least one surface acoustic wave filter adopts the surface acoustic wave filter according to any one of claims 1 to 16.

18. A multiplexer, comprising a transmitting end and a receiving end, characterized in that: At least one of the receiving end and / or the transmitting end includes at least one surface acoustic wave filter, and the surface acoustic wave filter is the surface acoustic wave filter according to any one of claims 1-16.

19. A radio frequency module, comprising at least one or more of a power amplifier, a low noise amplifier, a switch and an antenna and a surface acoustic wave filter, characterized in that: The surface acoustic wave filter adopts the surface acoustic wave filter according to any one of claims 1 to 16.

Images