Filter and method for manufacturing a filter

Abstract

A filter (100) and a method for fabricating the filter (100), the filter (100) comprising: a substrate (10); a series resonator (20), the series resonator (20) comprising a first Bragg reflector layer (201) and a first piezoelectric transducer structure (202) sequentially stacked on the substrate (10); and a parallel resonator (30), the parallel resonator (30) comprising a second Bragg reflector layer (301) and a second piezoelectric transducer structure (302) sequentially stacked on the substrate (10), the first Bragg reflector layer (201)... The structure of 1) is different from that of the second Bragg reflector (301); a series branch (C) including the series resonator (20) is coupled between the filter input (Vi) and the filter output (Vo); a parallel branch (P) including the parallel resonator (30) is coupled between the series branch (C) and the common ground (Gnd); this structure can improve the filtering performance of the filter (100).

Description

Technical Field

[0001] This application relates to the field of filter technology, and in particular to a filter and a method for manufacturing the filter. Background Technology

[0002] With the development of communication technology, the demand for radio frequency (RF) filters is increasing. When filters are applied to high-performance scenarios, such as 5G technology, a combination of a thin-film bulk acoustic resonator (BSA) and an LC resonant circuit is typically used to achieve RF band filtering.

[0003] In current technologies, when filters formed by thin-film bulk acoustic wave (TFT) resonators are combined with LC resonant circuits for high-performance applications, the TFT in the filter typically needs to be positioned at the edge of the high-performance radio frequency band's passband to achieve filtering at the 5G radio frequency band's passband edge. In this case, the filter's quality factor (Q) is low, reducing its filtering effectiveness. Therefore, improving the filtering performance of TFT filters in high-performance applications becomes a problem that needs to be solved. Summary of the Invention

[0004] The filter and its fabrication method provided in this application can improve the performance of the filter.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect, embodiments of this application provide a filter, comprising: a substrate; a series resonator, the series resonator comprising a first Bragg reflector layer and a first piezoelectric transducer structure sequentially stacked on the substrate; a parallel resonator, the parallel resonator comprising a second Bragg reflector layer and a second piezoelectric transducer structure sequentially stacked on the substrate, wherein the structure of the first Bragg reflector layer is different from the structure of the second Bragg reflector layer; a series branch, the series branch comprising the series resonator, the series branch being coupled between the filter input terminal and the filter output terminal; and a parallel branch, the parallel branch comprising the parallel resonator, the parallel branch being coupled between the series branch and a common ground.

[0007] The filter described in this application embodiment can be a bare die, which is an integrated circuit formed on a semiconductor through processes such as growth, doping, etching, or development. This integrated circuit includes an input terminal, an output terminal, at least one series resonator, and at least one parallel resonator to achieve filtering functionality. It should be noted that, in one possible implementation, the bare die used to form the filter can be encapsulated in a package formed of packaging material, and the input terminal, output terminal, and ground terminal are led out through the package to achieve signal transmission with external devices. In another possible implementation, the bare die used to form the filter can also be disposed on the same chip as other devices (such as capacitors and inductors) without packaging.

[0008] In this embodiment, by setting the Bragg reflector layer in the series resonator and the Bragg reflector layer in the parallel resonator to have different thicknesses, the transverse wave transmission coefficient of the series resonator and the parallel resonator can be changed. This results in a lower transverse wave transmission coefficient for each resonator within its effective frequency band, thereby improving the reflection efficiency of each resonator, which in turn improves the quality factor Q value of the resonator and thus improves the filtering effect of the filter.

[0009] Based on the first aspect, in one possible implementation, the filter further includes a low acoustic impedance structure for forming the first Bragg reflector layer and the second Bragg reflector layer; the first Bragg reflector layer includes a first high acoustic impedance structure embedded in the low acoustic impedance structure; the second Bragg reflector layer includes a second high acoustic impedance structure embedded in the low acoustic impedance structure; and along the stacking direction, the thickness of the first high acoustic impedance structure is different from the thickness of the second high acoustic impedance structure.

[0010] Based on the first aspect, in one possible implementation, the low acoustic impedance structure is stacked on the surface of the substrate; the filter further includes a first electrode and a thin film structure for forming the first piezoelectric transducer structure and the second piezoelectric transducer structure, the first electrode and the thin film structure being stacked sequentially on the surface of the low acoustic impedance structure away from the substrate; the first piezoelectric transducer structure further includes a second electrode, and the second piezoelectric transducer structure further includes a third electrode; both the first electrode and the second electrode are disposed on the surface of the thin film structure away from the substrate.

[0011] Based on the first aspect, in one possible implementation, along the stacking direction, the first high acoustic impedance structure includes a first surface remote from the substrate, the low acoustic impedance structure includes a first surface remote from the substrate, the second high acoustic impedance structure includes a first surface remote from the substrate, the first surface of the first high acoustic impedance structure and the first surface of the low acoustic impedance structure have a first distance, and the first surface of the second high acoustic impedance structure and the first surface of the low acoustic impedance structure have a second distance, the first distance and the second distance being different.

[0012] The first surface of the first high acoustic impedance structure can also be called the upper surface of the first high acoustic impedance structure, the first surface of the low acoustic impedance structure can also be called the upper surface of the low acoustic impedance structure, and the first surface of the second high acoustic impedance structure can also be called the upper surface of the first high acoustic impedance structure.

[0013] Based on the first aspect, in one possible implementation, the first Bragg reflector layer further includes a third high acoustic impedance structure embedded in the low acoustic impedance structure. Along the stacking direction, the third high acoustic impedance structure is disposed on the side of the first high acoustic impedance structure away from the substrate, and the low acoustic impedance structure is disposed between the third and the first high acoustic impedance structure. The second Bragg reflector layer further includes a fourth high acoustic impedance structure embedded in the low acoustic impedance structure. Along the stacking direction, the fourth high acoustic impedance structure is disposed on the side of the second high acoustic impedance structure away from the substrate, and the low acoustic impedance structure is disposed between the fourth and the second high acoustic impedance structure. Along the stacking direction, the thickness of the third high acoustic impedance structure is different from the thickness of the fourth high acoustic impedance structure.

[0014] Based on the first aspect, in one possible implementation, along the stacking direction, the thickness of the first high acoustic impedance structure is the same as the thickness of the fourth high acoustic impedance structure; and along the stacking direction, the thickness of the second high acoustic impedance structure is the same as the thickness of the third high acoustic impedance structure.

[0015] Based on the first aspect, in one possible implementation, the third high acoustic impedance structure includes a first surface remote from the substrate, and the upper surface of the first surface of the third high acoustic impedance structure has a third distance from the first surface of the low acoustic impedance structure; the fourth high acoustic impedance structure includes a first surface remote from the substrate, and the first surface of the third high acoustic impedance structure has a fourth distance from the first surface of the low acoustic impedance structure; the third distance and the fourth distance are different.

[0016] The first surface of the third high acoustic impedance structure can also be called the upper surface of the third high acoustic impedance structure, and the first surface of the fourth high acoustic impedance structure can also be called the upper surface of the fourth high acoustic impedance structure.

[0017] Based on the first aspect, in one possible implementation, the third high acoustic impedance structure includes a second surface near the substrate, and the second surface of the third high acoustic impedance structure has a fifth distance from the first surface of the first high acoustic impedance structure; the fourth high acoustic impedance structure includes a second surface near the substrate, and the second surface of the fourth structure has a sixth distance from the first surface of the second high acoustic impedance structure; the fifth distance is different from the sixth distance.

[0018] The second surface of the third high acoustic impedance structure can also be called the lower surface of the third high acoustic impedance structure, and the second surface of the fourth high acoustic impedance structure can also be called the lower surface of the fourth high acoustic impedance structure.

[0019] Based on the first aspect, in one possible implementation, the first high acoustic impedance structure includes a second surface near the substrate, the low acoustic impedance structure includes a second surface near the substrate, and a seventh distance exists between the second surface of the first high acoustic impedance structure and the second surface of the low acoustic impedance structure; the second high acoustic impedance structure includes a second surface near the substrate, and an eighth distance exists between the second surface of the second high acoustic impedance structure and the second surface of the low acoustic impedance structure; the seventh distance and the eighth distance are different.

[0020] The second surface of the first high acoustic impedance structure can also be called the lower surface of the first high acoustic impedance structure, the second surface of the second high acoustic impedance structure can also be called the lower surface of the second high acoustic impedance structure, and the second surface of the low acoustic impedance structure can also be called the lower surface of the low acoustic impedance structure.

[0021] Based on the first aspect, in one possible implementation, the materials of the first high acoustic impedance structure, the second high acoustic impedance structure, the third high acoustic impedance structure and the fourth high acoustic impedance structure include one of the following: W (tungsten), Mo (molybdenum), ALN (aluminum nitride) or Ta2O5 (tantalum pentoxide).

[0022] Based on the first aspect, in one possible implementation, the material of the low acoustic impedance structure includes one of the following: silicon dioxide or silicon nitride.

[0023] Secondly, embodiments of this application provide an electronic device including a transceiver, the transceiver including a filter as described in the first aspect.

[0024] Based on the second aspect, in one possible implementation, the electronic device further includes a circuit board, on which the transceiver is disposed. Specifically, the circuit board can be a printed circuit board (PCB).

[0025] Thirdly, embodiments of this application provide a method for fabricating a filter, the method comprising: providing a substrate; stacking a first Bragg reflector layer and a second Bragg reflector layer on the substrate; stacking a first piezoelectric transducer structure on the first Bragg reflector layer and stacking a second piezoelectric transducer structure on the second Bragg reflector layer; wherein the structures of the first Bragg reflector layer and the second Bragg reflector layer are different.

[0026] Based on the third aspect, in one possible implementation, stacking the first Bragg reflector layer and the second Bragg reflector layer on the substrate includes: depositing a low acoustic impedance material on the substrate to form a first low acoustic impedance layer; depositing a high acoustic impedance material on the surface of the first low acoustic impedance layer; patterning the high acoustic impedance material to form a first high acoustic impedance structure and a second high acoustic impedance structure, wherein the first high acoustic impedance structure and the second high acoustic impedance structure have different thicknesses along the deposition direction; and depositing a low acoustic impedance material on the surfaces of the first high acoustic impedance structure and the second high acoustic impedance structure to form a second low acoustic impedance layer, wherein the second low acoustic impedance layer and the first low acoustic impedance layer have an integral structure to form a low acoustic impedance structure. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of a filter provided in an embodiment of this application;

[0029] Figure 2 This is yet another structural schematic diagram of the filter provided in the embodiments of this application;

[0030] Figure 3 This is a cross-sectional view of the filter provided in an embodiment of this application;

[0031] Figure 4 This is yet another cross-sectional view of the filter provided in the embodiments of this application;

[0032] Figure 5 This is a cross-sectional view of a filter in traditional technology;

[0033] Figure 6 This is a schematic diagram showing the waveforms of the transverse wave transmission coefficient and longitudinal wave transmission coefficient of the resonator in a filter in traditional technology as a function of frequency.

[0034] Figure 7aThis is a schematic diagram showing the waveforms of the transverse wave transmission coefficient and longitudinal wave transmission coefficient of the series resonator in the filter provided in this application as a function of frequency.

[0035] Figure 7b This is a schematic diagram showing the waveforms of the transverse wave transmission coefficient and longitudinal wave transmission coefficient of the parallel resonator in the filter provided in this application embodiment as a function of frequency.

[0036] Figure 8 This is yet another cross-sectional view of the filter provided in the embodiments of this application;

[0037] Figure 9 This is yet another cross-sectional view of the filter provided in the embodiments of this application;

[0038] Figure 10 This is yet another cross-sectional view of the filter provided in the embodiments of this application;

[0039] Figure 11 This is a flowchart of a filter fabrication method provided in an embodiment of this application;

[0040] Figure 12 This is yet another flowchart of the filter fabrication method provided in the embodiments of this application;

[0041] Figures 13a-13k This is a schematic diagram of the structure during the fabrication process of the filter provided in the embodiments of this application;

[0042] Figure 14 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application;

[0043] Figure 15 This is a schematic diagram of the structure of a terminal device provided in an embodiment of this application. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] The terms "first," "second," and similar terms used in this article do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one" and similar terms do not indicate a quantity limitation, but rather indicate the existence of at least one. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect, equivalent to coupling or connection in a broad sense.

[0046] In this document, "module" generally refers to a logically divided functional structure. This "module" can be implemented purely in hardware or a combination of hardware and software. In the implementation of this application, "and / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone.

[0047] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units refer to two or more processing units; multiple systems refer to two or more systems.

[0048] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the filter structure provided in the embodiments of this application.

[0049] exist Figure 1 In the filter 100, there is an input terminal Vi, an output terminal Vo, a series branch C, and a parallel branch P. One end of the series branch C is coupled to the input terminal Vi, and the other end is coupled to the output terminal Vo. One end of the parallel branch P is coupled to the series branch C, and the other end is coupled to the common ground Gnd. A series resonator 20 is installed on the series branch C, and a parallel resonator 30 is installed on the parallel branch P. Figure 1 The filter 100 shown has a series resonator 20 in its series branch C, and a parallel branch P is coupled between the series branch C and the common ground Gnd.

[0050] In another possible implementation, multiple series resonators 20a, 20b...20n can be arranged on the series branch C. Furthermore, multiple parallel branches P1, P2,...Pn can be coupled between the series branch C and the common ground Gnd. Each parallel branch can have one parallel resonator 30, and each parallel branch can also have multiple parallel resonators 30. This application does not limit this. Specifically, for one of the multiple parallel branches P1, P2,...Pn, one end of this branch can be coupled to the position between every two series resonators on the series branch C, and the other end can be coupled to the common ground Gnd; or one end of this branch can be coupled to the output terminal Vo, and the other end can be coupled to the common ground Gnd. Specifically, as shown... Figure 2As shown, one end of the parallel branch P1 is coupled to node a1 between series resonators 20a and 20b, and the other end is connected to the common ground Gnd. One end of the parallel branch P2 is coupled to node a2 between series resonators 20b and 20c, and the other end is coupled to the common ground Gnd. One end of the parallel branch Pn is coupled to the output terminal Vo, and the other end is coupled to the common ground Gnd. Figure 2 The diagram illustrates the case where each parallel branch is equipped with a parallel resonator 30.

[0051] It should be noted that the filter described in this application embodiment can be a bare chip (i.e., a die), which is an integrated circuit formed on a semiconductor through processes such as growth, doping, etching, or development. This integrated circuit includes the aforementioned input terminal Vi, output terminal Vo, at least one series resonator, and at least one parallel resonator, thereby achieving the filtering function. It should also be noted that in one possible implementation, the filter 100 can be encapsulated in a package formed of packaging material, and the input terminal Vi, output terminal Vo, and ground terminal Gnd are led out through the package to achieve signal transmission with external devices. In another possible implementation, the filter 100 can also be disposed on the same chip as other devices (e.g., capacitors, inductors, etc.) without packaging.

[0052] based on Figure 1 and Figure 2 The filter 100 shown below is an example of a filter 100 that includes a parallel branch P, a parallel resonator 30 disposed on the parallel branch P, and a series resonator 20 disposed in the series branch (i.e., as shown in the example). Figure 1 (Taking filter 100 as an example), combined with Figure 3 The specific structure of filter 100 is described in detail.

[0053] Please refer to Figure 3 This shows a cross-sectional view of filter 100. (See image.) Figure 3As shown, the filter 100 includes a series resonator 20 and a parallel resonator 30. The series resonator 20 and the parallel resonator 30 can share the same substrate 10. Along the first direction Z, i.e., the stacking direction, the series resonator 20 includes a Bragg reflector layer 201 and a piezoelectric transducer structure 202 disposed on the Bragg reflector layer 201. Similarly, along the first direction Z, the parallel resonator 30 includes a Bragg reflector layer 301 and a piezoelectric transducer structure 302 disposed on the Bragg reflector layer 301. The piezoelectric transducer structure 202 includes an electrode 021 near the Bragg reflector layer 201, an electrode 2022 away from the Bragg reflector layer 201, and a piezoelectric thin film 023 disposed between the electrodes 021 and 2022. The piezoelectric transducer structure 302 includes an electrode 021 near the Bragg reflector layer 301, an electrode 3022 away from the Bragg reflector layer 301, and a piezoelectric thin film 023 disposed between the electrodes 021 and 3022. Figure 3 As shown, piezoelectric transducer structures 202 and 302 share the same electrode layer 021 and the same piezoelectric thin film 023. Electrodes 2022 and 3022 formed on the piezoelectric thin film 023 are separated from each other. The piezoelectric transducer structures 202 and 302 are the same as conventional piezoelectric transducer structures and will not be described further. It should be noted that an input terminal Vi can be led out from electrode 2022, an output terminal Vo can be led out from electrode 023, and a ground terminal Gnd can be led out from electrode 3022.

[0054] exist Figure 3 In the series resonator 20, the Bragg reflector layer 201 includes a low acoustic impedance structure D and a high acoustic impedance structure G1 embedded in the low acoustic impedance structure D. Similarly, the Bragg reflector layer 301 of the parallel resonator 30 includes a low acoustic impedance structure D and a high acoustic impedance structure G2 embedded in the low acoustic impedance structure D. Figure 3 As shown, the low acoustic impedance structure D is a continuous structure that encapsulates the high acoustic impedance structures G1 and G2. In this embodiment, the material of the low acoustic impedance structure D can be a semiconductor oxide such as silicon dioxide (SiO2). It should be noted that the Bragg reflector layer 201 may include the high acoustic impedance structure G1 and the portion of the low acoustic impedance structure D that is stacked with the high acoustic impedance structure G1; the Bragg reflector layer 301 may include the high acoustic impedance structure G2 and the portion of the low acoustic impedance structure D that is stacked with the high acoustic impedance structure G2.

[0055] It should be understood that both low acoustic impedance structures and high acoustic impedance structures refer to the parameter of acoustic impedance. Impedance refers to the resistance that needs to be overcome to displace a medium. Here, acoustic impedance can be defined as "sound pressure / velocity of the medium flowing through an area," or it can be expressed as "the product of medium density and sound velocity." A low acoustic impedance structure refers to a structure formed by a material with low acoustic impedance, while a high acoustic impedance structure is formed by a material with high acoustic impedance. The difference in acoustic impedance is relative. In the embodiments of this application, the materials forming high acoustic impedance structures G1 and G2 can be metallic materials, such as, but not limited to, tungsten (W) and molybdenum (Mo). In addition, the materials forming high acoustic impedance structures G1 and G2 can also be non-metallic materials, such as, but not limited to, aluminum nitride (ALN) or tantalum pentoxide (Ta2O5). When the material forming the high acoustic impedance structure is a metal oxide, along the second direction Y, high acoustic impedance structures G1 and G2 can be discontinuous structures, that is... Figure 3 The structure shown; when the material forming the high acoustic impedance structure is a non-metallic oxide, along the second direction Y, the high acoustic impedance structures G1 and G2 can be continuous structures, that is... Figure 4 The structure shown.

[0056] Continue reading Figure 3 and Figure 4 ,exist Figure 3 and Figure 4 In the filter 100 shown, along the first direction Z, the high acoustic impedance structure G1 in the series resonator 20 and the high acoustic impedance structure G2 in the parallel resonator 30 have different thicknesses. Figure 3 and Figure 4 The diagram schematically shows that the thickness of the high acoustic impedance structure G1 in the series resonator 20 is greater than the thickness of the high acoustic impedance structure G2 in the parallel resonator 30. In other possible implementations, the thickness of the high acoustic impedance structure G2 in the parallel resonator 30 may be greater than the thickness of the high acoustic impedance structure G1 in the series resonator 20. This application does not limit this aspect.

[0057] It should be noted that the filter 100 described in this application embodiment can be applied to scenarios in 3G / 4G and other radio frequency bands, as well as 5G radio frequency bands. 5G radio frequency bands typically have large bandwidth and high frequency. For example, the Band N77 radio frequency band in the 5G communication protocol has a passband frequency between 3.3GHz and 4.2GHz, with a bandwidth of 900MHz. In the 5G radio frequency band, when using a filter composed of a thin-film bulk acoustic wave resonator as a single device, it is usually impossible to achieve filtering of the aforementioned large bandwidth 5G frequency band. That is to say, in the 5G radio frequency band, the filtering of the aforementioned 5G radio frequency band can be achieved by combining a thin-film bulk acoustic wave resonator and an LC resonant circuit. In this implementation, it is usually necessary to place the series resonator and parallel resonator in the thin-film bulk acoustic wave resonator at the edge of the passband to achieve edge filtering of the passband. Taking the BandN77 as an example, the parallel resonator achieves filtering at the low passband edge frequency of 3.3 GHz, the series resonator achieves filtering at the high passband edge frequency of 4.2 GHz, and the LC resonant circuit further achieves overall filtering from 3.3 to 4.2 GHz, resulting in high suppression of the passband edges. This requires the series resonator in the thin-film bulk acoustic wave resonator to have high transverse and longitudinal wave reflection performance near 4.2 GHz, and similarly, the parallel resonator in the thin-film bulk acoustic wave resonator must also have high transverse and longitudinal wave reflection performance near 3.3 GHz.

[0058] In conventional filters, the Bragg reflector layer 401 in series resonator 40 and the Bragg reflector layer 501 in parallel resonator 50 have the same structure, that is, the high acoustic impedance structure 4011 in series resonator 40 and the high acoustic impedance structure 5011 in parallel resonator 50 have the same thickness along the first direction Z. Furthermore, the distance h1 between the upper surface of the high acoustic impedance structure 4011 and the upper surface of the low acoustic impedance structure 02 in series resonator 40 is the same as the distance h2 between the upper surface of the high acoustic impedance structure 5011 and the upper surface of the low acoustic impedance structure 02 in parallel resonator 50. Similarly, the distance h3 between the lower surface of the high acoustic impedance structure 4011 and the lower surface of the low acoustic impedance structure 02 in series resonator 40 is the same as the distance h4 between the lower surface of the high acoustic impedance structure 5011 and the lower surface of the low acoustic impedance structure 02 in parallel resonator 50. Figure 5 As shown. When as Figure 5 When the filter formed by the thin-film bulk acoustic wave resonator shown is applied in a 5G radio frequency band scenario, based on the structure and material properties of the thin-film bulk acoustic wave resonator, the schematic diagrams of the waveforms of the transverse wave transmission coefficient and the longitudinal wave transmission coefficient of the series resonator 40 and the parallel resonator 50 as a function of frequency are shown below. Figure 6 As shown. In Figure 6In the graph, the horizontal axis represents frequency (GHz), and the vertical axis represents transmission coefficient (dB). It should be noted that a lower transmission coefficient means less acoustic energy leaks through the substrate, resulting in better resonator performance. Figure 6 As can be seen, at a frequency around 3.3 GHz, the shear wave transmission coefficient of the parallel resonator 50 is around -12 dB; at a frequency around 4.2 GHz, the shear wave transmission coefficient of the series resonator 40 is around -17 dB. This means that in current technology, both the parallel resonator 50 and the series resonator 40 have high shear wave transmission coefficients within their operating range. With a high shear wave transmission coefficient, the resonator's reflection efficiency is low, meaning its quality factor (Q) is low, which reduces the filter's filtering effect.

[0059] And such Figure 3 or Figure 4 The waveforms of the transverse wave transmission coefficient and longitudinal wave transmission coefficient of the series resonator 20 in the filter 100 as a function of frequency are shown below. Figure 7a As shown, the waveforms of the transverse wave transmission coefficient and longitudinal wave transmission coefficient of the parallel resonator 30 as a function of frequency are as follows: Figure 7b As shown. From Figure 7a As can be seen, at a frequency around 4.2 GHz, the transverse wave transmission coefficient of the series resonator 20 is around -20 dB. Figure 7b As can be seen, at a frequency around 3.3 GHz, the transverse wave transmission coefficient of the parallel resonator 30 is around -21 dB. Therefore, the transverse wave transmission coefficients of each resonator in the filter 100 described in this embodiment are similar to... Figure 5 The transverse wave transmission coefficient of each resonator in the filter shown is significantly reduced compared to the previous one. Figure 7a and Figure 6 , Figure 7b and Figure 6 It can be seen that the longitudinal wave transmission coefficients of the series resonator 20 and the parallel resonator 30 are similar to those of... Figure 5 The longitudinal wave transmission coefficients of the conventional resonators shown are almost the same. Therefore, in this embodiment, by setting the high acoustic impedance material layer G1 of the Bragg reflector layer 201 in the series resonator 20 and the high acoustic impedance material layer G2 of the Bragg reflector layer 302 in the parallel resonator 30 to different thicknesses, the transverse wave transmission coefficients of the series resonator 20 and the parallel resonator 30 can be changed. This results in a lower transverse wave transmission coefficient for each resonator within its effective frequency band, improving the reflection efficiency of each resonator, that is, improving the quality factor Q of the resonator, and thus improving the filtering effect of the filter.

[0060] Figure 3 and Figure 4The illustration schematically shows a high acoustic impedance structure in both the series resonator 20 and the parallel resonator 30. In other possible implementations, both the series resonator 20 and the parallel resonator 30 can have multiple high acoustic impedance structures, such as two or three. Please refer to [reference needed]. Figure 8 It shows a schematic diagram of the Bragg reflector layer 201 in the series resonator 20 and the Bragg reflector layer 301 in the parallel resonator 30, which each includes two high acoustic impedance structures.

[0061] like Figure 8 As shown, the Bragg reflector layer 201 in the series resonator 20 includes high acoustic impedance structures G1 and G3, while the Bragg reflector layer 301 in the parallel resonator 30 includes high acoustic impedance structures G2 and G4. Among them, the high acoustic impedance structures G1 and G3... Figure 8 The high acoustic impedance structures G1 and G3 are arranged in a parallel manner, with a low acoustic impedance structure D positioned between them. Along the first direction Z, the high acoustic impedance structures G1 and G3 are parallel, and in the opposite direction of Z, the dimensions of the high acoustic impedance structures G1 and G3 perpendicular to the stacking direction (i.e., the dimensions extending along the second direction Y) gradually increase from top to bottom. In the entire resonator, the smaller high acoustic impedance structure G3 is closer to the electrode 021 side, and the larger high acoustic impedance structure G1 is closer to the substrate 10 side. This allows the waveform range to gradually increase as sound propagates from the electrode 021 side to the substrate 10 side, thus achieving matching with the sound wave and meeting the resonance requirements. Similarly, the high acoustic impedance structures G2 and G4 in the Bragg reflector layer 301... Figure 8 The structures are arranged in a parallel, top-to-bottom configuration, with a low-resistance structure D positioned between high-resistance structures G2 and G4. Along the first direction Z, the high-resistance structures G2 and G4 are parallel, and in the opposite direction of Z, the dimensions of the high-resistance structures G2 and G4 perpendicular to the stacking direction (i.e., the dimensions extending along the second direction Y) gradually increase from top to bottom. Figure 8 In the Bragg reflector layer 201, the high acoustic impedance structure G1 and the high acoustic impedance structure G2 in the Bragg reflector layer 301 have the same thickness along the first direction Z, while the high acoustic impedance structures G3 and G4 in the Bragg reflector layer 201 have different thicknesses. The materials forming the high acoustic impedance structure G3, G4, and G1 are the same. See reference [link to documentation]. Figure 3 The relevant descriptions in the document will not be repeated here.

[0062] It is understandable that the Bragg reflector layer 201 in the series resonator 20 and the Bragg reflector layer 301 in the parallel resonator 30 may also include a third high acoustic impedance structure, a fourth high acoustic impedance structure, and more high acoustic impedance structures. All high acoustic impedance structures are embedded in low acoustic impedance structures and are parallel to each other along the stacking direction. The dimensions of each high acoustic impedance structure extending along the second direction Y gradually increase from the electrode 021 towards the substrate 10. Of course, a low acoustic impedance structure is provided between any two high acoustic impedance structures, so that the high acoustic impedance structures and low acoustic impedance structures are in an alternating layered structure, which facilitates the propagation and reflection of sound in each layer. When including a third high acoustic impedance structure, a fourth high acoustic impedance structure, and more high acoustic impedance structures, the high acoustic impedance structure closest to electrode 021 in the series resonator 20 differs in thickness along the first direction Z from the high acoustic impedance structure closest to electrode 021 in the parallel resonator 30. For any of the other high acoustic impedance structures in the series resonator 20, the thickness along the first direction Z is the same as that of the high acoustic impedance structures arranged in the same layer in the parallel resonator 30. "In the same layer" here can be understood as: having the same position in the Bragg reflector layer. For example, Figure 8 The high acoustic impedance structures G1 and G2 shown can be understood as being arranged in the same layer, and the high acoustic impedance structures G3 and G4 can be understood as being arranged in the same layer. When the Bragg reflector layer 201 also includes a high acoustic impedance structure G5 located between the high acoustic impedance structures G1 and G3, and the Bragg reflector layer 301 also includes a high acoustic impedance structure G6 located between the high acoustic impedance structures G2 and G4, the high acoustic impedance structures G5 and G6 can be understood as being arranged in the same layer (not shown in the figure).

[0063] exist Figure 8 The diagram schematically illustrates a configuration where both the series resonator 20 and the parallel resonator 30 in the filter 100 include two high acoustic impedance structures, and the high acoustic impedance structure G1 near the substrate 10 in the series resonator 20 and the high acoustic impedance structure G2 near the substrate 10 in the parallel resonator 30 have the same thickness along the first direction Z. In some other possible implementations, the high acoustic impedance structures in the same layer of the series resonator 20 and the parallel resonator 30 have different thicknesses along the first direction Z. Please refer to [reference needed]. Figure 9 It shows that the high acoustic impedance structure G1 near the substrate 10 in the series resonator 20 and the high acoustic impedance structure G2 near the substrate 10 in the parallel resonator 30 have different thicknesses along the first direction Z. Figure 9 The remaining structure of each resonator shown, as well as the materials used, are similar to... Figure 2 The resonators shown have the same structure and use the same materials, so they will not be described again here. Furthermore, as... Figure 9As shown, the thickness of the high acoustic impedance structure G3 near the electrode 021 in the series resonator 20 along the first direction Z is the same as the thickness of the high acoustic impedance structure G2 near the substrate 10 in the parallel resonator 30 along the first direction Z; the thickness of the high acoustic impedance structure G4 near the electrode 021 in the parallel resonator 30 along the first direction Z is the same as the thickness of the high acoustic impedance structure G1 near the substrate 10 in the series resonator 20 along the first direction Z.

[0064] like Figure 9 In the embodiment shown, in addition to setting different thicknesses for the high acoustic impedance structure G1 and the high acoustic impedance structure G2 along the first direction Z, the high acoustic impedance structure G3 and the high acoustic impedance structure G4 are also set with different thicknesses along the first direction Z. That is, the high acoustic impedance structures set in the same layer of the series resonator 20 and the parallel resonator 30 have different thicknesses along the first direction Z, which can further improve the reflection efficiency of the resonator, that is, further improve the quality factor Q value of the resonator and improve the filtering effect of the filter.

[0065] from Figures 2-9 As can be seen in the embodiments shown, at least one layer of high acoustic impedance structure disposed in the same layer of the series resonator 20 and the parallel resonator 30 has a different thickness along the first direction Z. In other possible implementations, the high acoustic impedance structures in the same layer can be set with the same thickness along the first direction Z. The embedding position of the high acoustic impedance structure in the series resonator 20 within the low acoustic impedance structure can be adjusted, and the embedding position of the high acoustic impedance structure in the parallel resonator 30 within the low acoustic impedance structure can also be adjusted so that the distance between the upper surfaces of the high and low acoustic impedance structures in the series resonator 20 is different from the distance between the upper surfaces of the high and low acoustic impedance structures in the parallel resonator 30; or the distance between the lower surfaces of the high and low acoustic impedance structures in the series resonator 20 is different from the distance between the lower surfaces of the high and low acoustic impedance structures in the parallel resonator 30. This can also reduce the transverse wave transmission coefficient of the series resonator 20 and the parallel resonator 30, improve the reflection efficiency of each resonator, that is, improve the quality factor Q value of the resonator, and thus improve the filtering effect of the filter. The following will combine... Figure 10 The embodiments shown are described in detail below.

[0066] exist Figure 10 In, such as Figure 10In the filter 100 shown, the Bragg reflector layer 201 of the series resonator 20 includes a high acoustic impedance structure G1 and a high acoustic impedance structure G3. The high acoustic impedance structure G1 is disposed on the side near the substrate 10, and the high acoustic impedance structure G3 is disposed on the side near the electrode 021. The Bragg reflector layer 301 of the parallel resonator 30 includes a high acoustic impedance structure G2 and a high acoustic impedance structure G4. The high acoustic impedance structure G2 is disposed on the side near the substrate 10, and the high acoustic impedance structure G4 is disposed on the side near the electrode 021. Specifically, the high acoustic impedance structure G1 includes an upper surface near the electrode 021 and a lower surface away from the electrode 021, and the high acoustic impedance structure G3 includes an upper surface near the electrode 021 and a lower surface away from the electrode 021. Similarly, the high acoustic impedance structure G2 includes an upper surface near the electrode 021 and a lower surface away from the electrode 021, and the high acoustic impedance structure G4 includes an upper surface near the electrode 021 and a lower surface away from the electrode 021. The low acoustic impedance structure D includes an upper surface near electrode 021 and a lower surface near substrate 10. A first distance h1 exists between the upper surface of the high acoustic impedance structure G3 and the upper surface of the low acoustic impedance structure D, and a second distance h2 exists between the upper surfaces of the high acoustic impedance structure G3 and the low acoustic impedance structure D, wherein the first distance h1 and the second distance h2 are different. A third distance h5 exists between the lower surface of the high acoustic impedance structure G3 and the upper surface of the high acoustic impedance structure G1, and a fourth distance h6 exists between the lower surface of the high acoustic impedance structure G4 and the upper surface of the high acoustic impedance structure G2, wherein the third distance h5 and the fourth distance h6 are different.

[0067] Based on the structures of the filters 100 described above, this application embodiment also provides a method for manufacturing the filters 100. The process flow for manufacturing the filters 100 can be referred to... Figure 11 The process flow 1100 shown is as follows. This process flow 1100 includes the following steps:

[0068] 1101: Provide a substrate; the substrate material here may be silicon.

[0069] 1102: A first Bragg reflective layer and a second Bragg reflective layer are formed on a substrate; wherein the first Bragg reflective layer and the second Bragg reflective layer have different structures.

[0070] The first Bragg reflector layer includes a first low acoustic impedance structure and a first high acoustic impedance structure embedded in the first low acoustic impedance structure, and the second Bragg reflector layer includes a second low acoustic impedance structure and a second high acoustic impedance structure embedded in the second low acoustic impedance structure.

[0071] In one possible implementation, the first high acoustic impedance structure and the second high acoustic impedance structure have different thicknesses along the deposition direction.

[0072] In one possible implementation, the first Bragg reflector layer includes a first low acoustic impedance structure and a first high acoustic impedance structure and a third high acoustic impedance structure embedded within the first low acoustic impedance structure. The third high acoustic impedance structure is formed on top of the first high acoustic impedance structure and is parallel to the first high acoustic impedance structure along the stacking direction. The second Bragg reflector layer includes a second low acoustic impedance structure and a second high acoustic impedance structure and a fourth high acoustic impedance structure embedded within the second low acoustic impedance structure. The fourth high acoustic impedance structure is formed on top of the second high acoustic impedance structure and is parallel to the second high acoustic impedance structure along the stacking direction. The first and second high acoustic impedance structures have different thicknesses along the deposition direction, and the third and fourth high acoustic impedance structures also have different thicknesses along the deposition direction. Alternatively, the first and fourth high acoustic impedance structures may have the same thickness along the deposition direction, and the second and third high acoustic impedance structures may have the same thickness along the deposition direction.

[0073] In one possible implementation, there is a first distance between the surface of the first high acoustic impedance structure away from the substrate and the surface of the first low acoustic impedance structure away from the substrate, and there is a second distance between the surface of the second high acoustic impedance structure away from the substrate and the surface of the second low acoustic impedance structure away from the substrate, wherein the lengths of the first distance and the second distance are different.

[0074] In one possible implementation, there is a third distance between the surface of the first high acoustic impedance structure near the substrate and the surface of the first low acoustic impedance structure near the substrate, and there is a fourth distance between the surface of the second high acoustic impedance structure near the substrate and the surface of the second low acoustic impedance structure near the substrate, wherein the lengths of the third distance and the fourth distance are different.

[0075] In one possible implementation, there is a fifth distance between the surface of the first high acoustic impedance structure away from the substrate and the surface of the third high acoustic impedance structure close to the substrate, and a sixth distance between the surface of the second high acoustic impedance structure away from the substrate and the surface of the fourth high acoustic impedance structure close to the substrate, wherein the lengths of the fifth distance and the sixth distance are different.

[0076] 1103: A first piezoelectric transducer structure and a second piezoelectric transducer structure are formed on the first Bragg reflector layer and the second Bragg reflector layer, respectively.

[0077] The first piezoelectric transducer structure includes a first piezoelectric layer near the first Bragg reflector, a second piezoelectric layer away from the first Bragg reflector, and a thin film layer located between the first and second piezoelectric layers; the second piezoelectric transducer structure includes a first piezoelectric layer near the second Bragg reflector, a second piezoelectric layer away from the second Bragg reflector, and a thin film layer located between the first and second piezoelectric layers.

[0078] Thus, the first Bragg reflector and the first piezoelectric transducer form a series resonator, and the second Bragg reflector and the second piezoelectric transducer form a parallel resonator.

[0079] The following describes the preparation of such... Figure 9 Taking the filter 100 shown as an example, the fabrication method of the filter 100 will be described in detail. Fabrication as follows... Figure 9 The manufacturing process of the filter 100 shown can be referenced. Figure 12 The process flow 1200 is shown. This process flow 1200 includes the following steps:

[0080] Step 1201, a substrate 10 is provided; the substrate material here can be silicon.

[0081] Step 1202: Grow a first low acoustic impedance material on the substrate. The first low acoustic impedance material can be a semiconductor material, such as SiO2.

[0082] Step 1203: Grow a first high acoustic impedance material on the first low acoustic impedance material. This step is followed by... Figure 13a As shown.

[0083] In a specific implementation, the first high acoustic impedance material can be a metallic material, including but not limited to: tungsten (W) and molybdenum (Mo).

[0084] Step 1204: A second acoustic impedance material is grown on the first high acoustic impedance material and the first low acoustic impedance material to form a high acoustic impedance structure G1 and a high acoustic impedance structure G2.

[0085] Specifically, a second high acoustic impedance material is deposited on the first high acoustic impedance material and the exposed first low acoustic impedance material, and then etched to form high acoustic impedance structures G1 and G2. Along the deposition direction, the thickness of high acoustic impedance structure G1 is greater than the thickness of high acoustic impedance structure G2; that is, the exposed upper surface of high acoustic impedance structure G1 is higher than the upper surface of high acoustic impedance structure G2. For example... Figure 13b As shown.

[0086] The second high acoustic impedance material can be etched using etching methods such as dry etching or wet etching.

[0087] As can be seen from steps 1203 and 1204, the high acoustic impedance structure G1 is formed by growing high acoustic impedance materials twice. The second high acoustic impedance material can be the same as the first high acoustic impedance material.

[0088] Step 1205: A second low acoustic impedance material and a third low acoustic impedance material are grown on the exposed high acoustic impedance structures G1 and G2, respectively, so that the second low acoustic impedance material covers the exposed portion of the high acoustic impedance structure G1, and the third low acoustic impedance material also covers the exposed portion of the high acoustic impedance structure G2. Along the stacking direction, the thickness of the second low acoustic impedance material grown on the high acoustic impedance structure G1 is the same as the thickness of the third low acoustic impedance material grown on the high acoustic impedance structure G2. Figure 13c As shown.

[0089] The second and third low acoustic impedance materials can be SiO2.

[0090] Step 1206: Grow a third high acoustic impedance material on the third low acoustic impedance material. For example... Figure 13d As shown.

[0091] Step 1207: A fourth high acoustic impedance material is grown on the third high acoustic impedance material and the second low acoustic impedance material to form high acoustic impedance structures G3 and G4, as follows. Figure 13e As shown.

[0092] Here, the third and fourth high acoustic impedance materials are the same. These materials can be metallic, including but not limited to tungsten (W) and molybdenum (Mo).

[0093] Thus, the fourth high acoustic impedance material grown on the second low acoustic impedance material forms a high acoustic impedance structure G3, and the third and fourth high acoustic impedance materials grown on the third low acoustic impedance material together form a high acoustic impedance structure G4. The thickness of the high acoustic impedance structure G4 is greater than the thickness of the high acoustic impedance structure G3 along the stacking direction. Furthermore, by controlling the growth and etching amounts of the third and fourth high acoustic impedance materials, the thickness of the high acoustic impedance structure G3 along the stacking direction can be made the same as the thickness of the high acoustic impedance structure G2 along the stacking direction, and the thickness of the high acoustic impedance structure G4 along the stacking direction can be the same as the thickness of the high acoustic impedance structure G1 along the stacking direction.

[0094] Step 1208: A fourth low acoustic impedance material is grown on the exposed portions of the high acoustic impedance structure G3, the high acoustic impedance structure G4, the first low acoustic impedance material, the second low acoustic impedance material, and the third low acoustic impedance material, such that the fourth low acoustic impedance material encapsulates the exposed portions of the high acoustic impedance structure G3, the high acoustic impedance structure G4, the first low acoustic impedance material, the second low acoustic impedance material, and the third low acoustic impedance material, as shown below. Figure 13f As shown. The fourth low acoustic impedance material can be SiO2.

[0095] Step 1209: Planarize the low acoustic impedance material in the fourth location.

[0096] Specifically, excess fourth low acoustic impedance material can be removed using a chemical mechanical polishing (CMP) process, thereby making the exposed surface of the fourth low acoustic impedance material flat. For example... Figure 13g As shown.

[0097] Step 1210: Continue growing a fifth low acoustic impedance material on the fourth low acoustic impedance material, and planarize the fifth low acoustic impedance material to form a low acoustic impedance structure D. For example... Figure 13h As shown.

[0098] Specifically, excess fifth low acoustic impedance material can be removed using a chemical mechanical polishing (CMP) process, thereby making the exposed surface of the fifth low acoustic impedance material flat.

[0099] Thus, the first, second, third, fourth, and fifth low acoustic impedance materials are connected together to form a continuous low acoustic impedance structure. Furthermore, the portions of this continuous low acoustic impedance structure that are stacked with high acoustic impedance structures G1 and G3 form a Bragg reflector layer 201, and the portions of this continuous low acoustic impedance structure that are stacked with high acoustic impedance structures G2 and G4 form a Bragg reflector layer 301.

[0100] Step 1211: Deposit a first metal layer on the low acoustic impedance structure D to form electrode 021. For example... Figure 13i As shown.

[0101] Step 1212: Deposit piezoelectric thin film material on electrode 021 to form piezoelectric thin film 023. For example... Figure 13j As shown.

[0102] Step 1213: Deposit a second metal layer on the piezoelectric thin film 023. For example... Figure 13k As shown.

[0103] Step 1214: Pattern the second metal layer to form mutually separated electrodes 2022 and 3022.

[0104] In the specific process, a patterned mask layer can be formed on the second metal layer. Using this patterned mask layer as a mask, the second metal layer is etched, and the unetched portions form electrodes 2022 and 3022. Various etching methods, such as dry etching or wet etching, can be used to etch the second metal layer to form electrodes 2022 and 3022.

[0105] The filter prepared through steps 1201-1214 is as follows: Figure 9 As shown.

[0106] Electrode 2022 is disposed on high acoustic impedance structures G1 and G3, and its orthographic projection onto high acoustic impedance structure G3 at least partially overlaps with high acoustic impedance structure G3. Electrode 3022 is disposed on high acoustic impedance structures G2 and G4, and its orthographic projection onto high acoustic impedance structure G4 at least partially overlaps with high acoustic impedance structure G4. Thus, electrode 021, piezoelectric thin film layer 023, and electrode 2022 located on high acoustic impedance structure G3 together form piezoelectric transducer structure 202, and electrode 021, piezoelectric thin film layer 023, and electrode 3022 located on high acoustic impedance structure G4 together form piezoelectric transducer structure 302. As a result, a series resonator 20 is formed between Bragg reflector layer 201 and piezoelectric transducer structure 202, and a resonator 20 is formed between Bragg reflector layer 301 and piezoelectric transducer structure 302.

[0107] The embodiments of this application employ, as follows: Figure 12 The filter manufactured by the process steps shown can change the transverse wave transmission coefficient of the series resonator and the parallel resonator, thereby making the transverse wave transmission coefficient of each resonator lower in its effective frequency band, improving the reflection efficiency of each resonator, that is, improving the quality factor Q value of the resonator, and thus improving the filtering effect of the filter.

[0108] In one possible implementation, the process steps in steps 1203 and 1204 above, which form the high acoustic impedance structure G1 and the high acoustic impedance structure G2, can also be replaced by the following steps:

[0109] A first high acoustic impedance material and a second high acoustic impedance material are grown on a first low acoustic impedance material, wherein the grown first high acoustic impedance material and the second high acoustic impedance material are discontinuous, and the upper surface of the first high acoustic impedance material is flush with the upper surface of the second high acoustic impedance material; the second high acoustic impedance material is etched, thereby forming a high acoustic impedance structure G1 from the first high acoustic impedance material, and forming a high acoustic impedance structure G2 from the etched second high acoustic impedance material.

[0110] Furthermore, in one possible implementation, the process steps in steps 1206 and 1207 above for forming the high acoustic impedance structure G3 and the high acoustic impedance structure G4 can be replaced by the following steps:

[0111] A third high acoustic impedance material is grown on a second low acoustic impedance material, and a fourth high acoustic impedance material is grown on the third low acoustic impedance material. The grown third and fourth high acoustic impedance materials are discontinuous, and the thickness of the grown third high acoustic impedance material along the stacking direction is the same as the thickness of the fourth high acoustic impedance material along the stacking direction. The third high acoustic impedance material is etched, so that the etched third high acoustic impedance material forms a high acoustic impedance structure G3, and the fourth high acoustic impedance material forms a high acoustic impedance structure G4.

[0112] This application also provides an electronic device 1400, please refer to... Figure 14 The electronic device 1400 may include a transceiver 1401, a memory 1402, and a processor 1403. The transceiver 1401 contains the aforementioned filter 100, the structure of which can be referred to Figure 1 or Figure 2 One of the structures shown in the example.

[0113] It should be understood that the electronic device 1400 here can specifically refer to terminal devices such as smartphones, computers, and smartwatches. The terminal device is... Figure 15 The smartphone 1510 shown is an example, and it may specifically include a processor 15102, a memory 15103, a control circuit, an antenna, and input / output devices. The processor 15102 is mainly used to process communication protocols and communication data, control the entire smartphone, execute software programs, and process data from these programs, such as supporting the smartphone 1510 in implementing various communication functions (e.g., making calls, sending messages, or instant messaging). The memory 15103 is mainly used to store software programs and data. The control circuit is mainly used for converting baseband signals to radio frequency signals and processing radio frequency signals; the control circuit includes the aforementioned filter 100. The control circuit and antenna together can also be called a transceiver 15101, mainly used for transmitting and receiving radio frequency signals in the form of electromagnetic waves. Input / output devices, such as a touchscreen, display screen, and keyboard, are mainly used to receive user input data and output data to the user.

[0114] When the smartphone 1510 is powered on, the processor 15102 can read the software program in the memory 15103, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be transmitted wirelessly, the processor 15102 performs baseband processing on the data to be transmitted and outputs the baseband signal to the radio frequency (RF) circuit. The RF circuit processes the baseband signal and transmits the RF signal outward in the form of electromagnetic waves through the antenna. When data is sent to the smartphone 1510, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor 15102. The processor 15102 converts the baseband signal into data and processes the data.

[0115] Those skilled in the art will understand that, for ease of explanation, Figure 15 Only one memory and one processor are shown. In actual terminal devices, multiple processors and multiple memories may exist. Memory can also be called storage medium or storage device, etc. It should be noted that the type of memory is not limited in the embodiments of this application.

[0116] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A filter, characterized in that, include: Substrate; A series resonator, the series resonator comprising a first Bragg reflector layer and a first piezoelectric transducer structure sequentially stacked on the substrate; A parallel resonator, comprising a second Bragg reflector layer and a second piezoelectric transducer structure stacked sequentially on the substrate, wherein the structure of the first Bragg reflector layer is different from the structure of the second Bragg reflector layer; A series branch, the series branch including the series resonator, the series branch being coupled between the filter input terminal and the filter output terminal; A parallel branch, the parallel branch including the parallel resonator, the parallel branch being coupled between the series branch and the common ground; The filter also includes a low acoustic impedance structure for forming the first Bragg reflector layer and the second Bragg reflector layer; The first Bragg reflector layer includes a first high acoustic impedance structure embedded in the low acoustic impedance structure; The second Bragg reflector layer includes a second high acoustic impedance structure embedded in the low acoustic impedance structure; Along the stacking direction, the thickness of the first high acoustic impedance structure is different from the thickness of the second high acoustic impedance structure.

2. The filter according to claim 1, characterized in that, The low acoustic impedance structure is stacked on the surface of the substrate; The filter further includes a first electrode and a thin film structure for forming the first piezoelectric transducer structure and the second piezoelectric transducer structure, wherein the first electrode and the thin film structure are stacked sequentially on the surface of the low acoustic impedance structure away from the substrate; The first piezoelectric transducer structure further includes a second electrode, and the second piezoelectric transducer structure further includes a third electrode; Both the second electrode and the third electrode are disposed on the surface of the thin film structure away from the substrate.

3. The filter according to claim 1 or 2, characterized in that, Along the stacking direction, the first high acoustic impedance structure includes a first surface remote from the substrate, the low acoustic impedance structure includes a first surface remote from the substrate, and there is a first distance between the first surface of the first high acoustic impedance structure and the first surface of the low acoustic impedance structure; Along the stacking direction, the second high acoustic impedance structure includes a first surface remote from the substrate, and the first surface of the second high acoustic impedance structure has a second distance from the first surface of the low acoustic impedance structure; The first distance and the second distance are different.

4. The filter according to claim 1 or 2, characterized in that, The first Bragg reflector layer further includes a third high acoustic impedance structure embedded in the low acoustic impedance structure. Along the stacking direction, the third high acoustic impedance structure is disposed parallel to the side of the first high acoustic impedance structure away from the substrate, and the low acoustic impedance structure is disposed between the third and the first high acoustic impedance structure. The second Bragg reflector layer further includes a fourth high acoustic impedance structure embedded in the low acoustic impedance structure. Along the stacking direction, the fourth high acoustic impedance structure is disposed parallel to the side of the second high acoustic impedance structure away from the substrate, and the low acoustic impedance structure is disposed between the second high acoustic impedance structure and the second high acoustic impedance structure. Along the stacking direction, the thickness of the third high acoustic impedance structure is different from the thickness of the fourth high acoustic impedance structure.

5. The filter according to claim 4, characterized in that, Along the stacking direction, the thickness of the first high acoustic impedance structure is the same as the thickness of the fourth high acoustic impedance structure; Along the stacking direction, the thickness of the second high acoustic impedance structure is the same as the thickness of the third high acoustic impedance structure.

6. The filter according to claim 4, characterized in that, Along the stacking direction, the third high acoustic impedance structure includes a first surface remote from the substrate, the low acoustic impedance structure includes a first surface remote from the substrate, and a third distance exists between the first surface of the third high acoustic impedance structure and the first surface of the low acoustic impedance structure. Along the stacking direction, the fourth high acoustic impedance structure includes a first surface remote from the substrate, and the first surface of the fourth high acoustic impedance structure has a fourth distance from the first surface of the low acoustic impedance structure; The third distance is different from the fourth distance.

7. The filter according to claim 4, characterized in that, Along the stacking direction, the third high acoustic impedance structure includes a second surface close to the substrate, the first high acoustic impedance structure includes a first surface away from the substrate, and there is a fifth distance between the second surface of the third high acoustic impedance structure and the first surface of the first high acoustic impedance structure; Along the stacking direction, the fourth high acoustic impedance structure includes a second surface close to the substrate, the second high acoustic impedance structure includes a first surface away from the substrate, and a sixth distance exists between the second surface of the fourth high acoustic impedance structure and the first surface of the second high acoustic impedance structure. The fifth distance and the sixth distance are different.

8. The filter according to any one of claims 1, 2, 5-7, characterized in that, The first high acoustic impedance structure includes a second surface near the substrate, the low acoustic impedance structure includes a second surface near the substrate, and there is a seventh distance between the second surface of the first high acoustic impedance structure and the second surface of the low acoustic impedance structure. The second high acoustic impedance structure includes a second surface close to the substrate, and there is an eighth distance between the second surface of the second high acoustic impedance structure and the second surface of the low acoustic impedance structure; The seventh distance and the eighth distance are different.

9. The filter according to any one of claims 1, 2, 5-7, characterized in that, The material of the low acoustic impedance structure includes one of the following: silicon dioxide or silicon nitride.

10. The filter according to claim 4, characterized in that, The materials of the first high acoustic impedance structure, the second high acoustic impedance structure, the third high acoustic impedance structure and the fourth high acoustic impedance structure include one of the following: tungsten, molybdenum, aluminum nitride or tantalum pentoxide.

11. An electronic device, characterized in that, The electronic device includes a transceiver, the transceiver including a filter as described in any one of claims 1-10.

12. The electronic device according to claim 11, characterized in that, The electronic device also includes a circuit board, and the transceiver is disposed on the circuit board.

13. A method for fabricating a filter, characterized in that, include: Provide a substrate; A first Bragg reflective layer and a second Bragg reflective layer are stacked on the substrate; A first piezoelectric transducer structure is stacked on the first Bragg reflector layer, and a second piezoelectric transducer structure is stacked on the second Bragg reflector layer; wherein... The first Bragg reflector and the second Bragg reflector have different structures; The stacking of the first Bragg reflective layer and the second Bragg reflective layer on the substrate includes: A low acoustic impedance material is deposited on the substrate to form a first low acoustic impedance layer; A high acoustic resistance material is deposited on the surface of the first low acoustic resistance layer; The high acoustic impedance material is patterned to form a first high acoustic impedance structure and a second high acoustic impedance structure, the first high acoustic impedance structure and the second high acoustic impedance structure having different thicknesses along the deposition direction.

14. The preparation method according to claim 13, characterized in that, The stacking of the first Bragg reflective layer and the second Bragg reflective layer on the substrate further includes: A low acoustic impedance material is deposited on the surfaces of the first high acoustic impedance structure and the second high acoustic impedance structure to form a second low acoustic impedance layer, wherein the second low acoustic impedance layer and the first low acoustic impedance layer have an integral structure to form a low acoustic impedance structure.

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