Bulk acoustic wave filter and method of manufacturing the same

Abstract

The application discloses a bulk acoustic wave filter and a manufacturing method thereof. The bulk acoustic wave filter comprises a carrier substrate, a piezoelectric layer and an electrode structure deposited on the carrier substrate, and a cavity structure formed on the carrier substrate. The cavity structure comprises a working area corresponding to an overlapping area of the electrode structure and the piezoelectric layer and a non-working area surrounding the working area. The electrode structure comprises at least one extension edge and a plurality of cut-off edges. The non-working area comprises an extension cavity area corresponding to the extension edge and a cut-off cavity area corresponding to the cut-off edge. The distance from the extension edge to the boundary of the extension cavity area is greater than the distance from the cut-off edge to the boundary of the cut-off cavity area.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a bulk acoustic wave filter and its manufacturing method. Background Technology

[0002] Figure 1 This is a top view of an existing bulk acoustic wave filter. Figure 2 This is a cross-sectional view of an existing bulk acoustic wave filter. (Reference) Figure 1 and Figure 2 As shown, in the bulk acoustic wave filter, the cavity region corresponding to the overlapping area of ​​the upper electrode layer 340, the lower electrode layer 330, and the piezoelectric layer 200 is the working region of the bulk acoustic wave filter. Furthermore, the second extending edge 312 of the upper electrode layer 340 also extends with a corresponding second extending portion 342, and the first extending edge 311 of the lower electrode layer 330 also extends with a corresponding first extending portion 332. In the prior art, the distance 343 from the second extending edge 312 of the upper electrode layer 340 to the boundary of the cavity structure 400 is equal to the distance 344 from the other edges of the upper electrode layer 340 (i.e., edges other than the second extending edge 312) to the boundary of the cavity structure 400.

[0003] Similarly, in the prior art, the distance 333 from the first extended edge 311 of the lower electrode layer 330 to the boundary of the cavity structure 400 is equal to the distance 334 from the other edges of the lower electrode layer 330 (i.e., the edges other than the first extended edge 311) to the boundary of the cavity structure 400.

[0004] Furthermore, for a bulk acoustic wave filter, its operating region requires a significant acoustic impedance abrupt change boundary to reflect acoustic wave energy back to the operating region, thereby forming an efficient resonance. However, since the distances from the second extension edge 312 of the upper electrode layer 340 and the first extension edge 311 of the lower electrode layer 330 to the boundary of the cavity structure 400 are equal to the distances from the other edges to the cavity structure 400, this effectively eliminates the impedance abrupt change at the acoustic boundary.

[0005] In other words, when sound waves propagate to the edge of the working region, if the electrodes extend continuously and uniformly in the non-working region, the sound waves will encounter a gradual transition from high impedance to low impedance, rather than a steep reflection boundary. This causes some sound wave energy to leak into the substrate instead of being reflected back to the working region, resulting in irreversible energy dissipation. This energy leakage directly leads to a decrease in the Q value of the bulk acoustic wave filter, thus affecting the overall performance of the bulk acoustic wave filter.

[0006] The existing technology has a technical problem where the electrodes extend continuously and uniformly in the non-working area, which is equivalent to eliminating impedance abrupt changes at the acoustic boundary. This causes some acoustic energy to leak to the substrate, resulting in irreversible energy dissipation, which in turn leads to a decrease in the Q value of the bulk acoustic wave filter and even affects the overall performance of the bulk acoustic wave filter. There is currently no effective solution to this problem. Summary of the Invention

[0007] This disclosure provides a bulk acoustic wave filter and its fabrication method, which at least solves the technical problem in the prior art where the electrodes extend continuously and uniformly in the non-working area, which is equivalent to eliminating impedance abrupt changes at the acoustic boundary. This causes some acoustic wave energy to leak to the substrate, resulting in irreversible energy dissipation, which in turn leads to a decrease in the Q value of the bulk acoustic wave filter and even affects the overall performance of the bulk acoustic wave filter.

[0008] According to one aspect of this application, a bulk acoustic wave filter is provided, comprising: a carrier substrate, a piezoelectric layer and an electrode structure deposited on the carrier substrate, and a cavity structure formed on the carrier substrate, wherein the cavity structure includes a working region corresponding to the overlapping region of the electrode structure and the piezoelectric layer and a non-working region surrounding the working region; the electrode structure includes at least one extending edge and a plurality of cutting edges, the non-working region includes an extending cavity region corresponding to the extending edge and a cutting cavity region corresponding to the cutting edge; and the distance from the extending edge to the boundary of the extending cavity region is greater than the distance from the cutting edge to the boundary of the cutting cavity region.

[0009] Optionally, it includes: a fence layer deposited on a carrier substrate, and the electrode structure includes a lower electrode layer deposited on the fence layer, and the lower electrode layer includes a first extended edge and a plurality of first cut-off edges, the non-working area includes a first extended cavity region corresponding to the first extended edge and a first cut-off cavity region corresponding to the first cut-off edge; and the distance from the first extended edge to the boundary of the first extended cavity region is greater than the distance from the first cut-off edge to the boundary of the first cut-off cavity region.

[0010] Optionally, the distance from the first extending edge to the boundary of the first extending cavity region is 1.5 to 3 times the distance from the first cutting edge to the boundary of the first cutting-off cavity region.

[0011] Alternatively, the piezoelectric layer is deposited on the fence layer and the lower electrode layer.

[0012] Optionally, the electrode structure includes an upper electrode layer deposited on the piezoelectric layer, and the upper electrode layer includes a second extended edge and a plurality of second cut-off edges. The non-working region includes a second extended cavity region corresponding to the second extended edge and a second cut-off cavity region corresponding to the second cut-off edge. The distance from the second extended edge to the boundary of the second extended cavity region is greater than the distance from the second cut-off edge to the boundary of the second cut-off cavity region.

[0013] Optionally, the distance from the second extending edge to the boundary of the second extending cavity region is 1.5 to 3 times the distance from the second cutting edge to the boundary of the second cutting-off cavity region.

[0014] According to another aspect of this application, a method for fabricating a bulk acoustic wave filter is provided, comprising: providing a substrate to be removed; depositing a piezoelectric layer and an electrode structure on the substrate to be removed, and etching the electrode structure to form a cavity structure, wherein the cavity structure includes a working region corresponding to the overlapping region of the electrode structure and the piezoelectric layer and a non-working region surrounding the working region; the electrode structure forming at least one extended edge and a plurality of cut-off edges, and the non-working region forming an extended cavity region corresponding to the extended edge and a cut-off cavity region corresponding to the cut-off edge, wherein the distance from the extended edge to the boundary of the extended cavity region is greater than the distance from the cut-off edge to the boundary of the cut-off cavity region.

[0015] Optionally, the operation of depositing a piezoelectric layer and an electrode structure on the substrate to be removed, and etching the electrode structure to form a cavity structure includes: depositing an upper electrode layer on the substrate to be removed, and depositing a piezoelectric layer on the upper electrode layer; depositing and etching a lower electrode layer on the piezoelectric layer to form a first region for exposing the piezoelectric layer; depositing and etching a sacrificial layer on the lower electrode layer and the piezoelectric layer to form a second region for exposing the piezoelectric layer and a third region for exposing the lower electrode layer; depositing a fence layer on the second region, the third region and the sacrificial layer; depositing a carrier substrate on the fence layer; flipping and removing the entire substrate to be removed; etching the upper electrode layer to form a fourth region for exposing the piezoelectric layer; and etching the sacrificial layer to form a cavity structure.

[0016] Optionally, the operation of depositing and etching a lower electrode layer on the piezoelectric layer includes: etching the lower electrode layer based on a pre-defined etching pattern to form a first extension; determining a first extension edge corresponding to the first extension edge, and a plurality of first cut-off edges other than the first extension edge.

[0017] Optionally, the operation of depositing and etching a sacrificial layer on the lower electrode layer and the piezoelectric layer includes: etching the sacrificial layer based on a pre-defined etching pattern and forming a first protrusion corresponding to the first extension edge.

[0018] Optionally, the operation of eroding the sacrificial layer and forming a cavity structure includes: eroding the sacrificial layer and forming a first extended cavity region corresponding to the first extended edge and a first cut-off cavity region corresponding to the first cut-off edge based on the first protrusion, wherein the distance from the first extended edge to the boundary of the first extended cavity region is greater than the distance from the first cut-off edge to the boundary of the first cut-off cavity region.

[0019] Optionally, the operation of depositing and etching a sacrificial layer on the lower electrode layer and the piezoelectric layer includes: etching the sacrificial layer based on a pre-defined etching pattern and forming a second protrusion corresponding to the second extension edge of the upper electrode layer.

[0020] Optionally, the etching operation of the upper electrode layer includes: etching the upper electrode layer based on a preset etching pattern to form a second extension; determining a second extension edge corresponding to the second extension edge, and a plurality of second cut-off edges other than the second extension edge.

[0021] Optionally, the operation of corroding the sacrificial layer and forming a cavity structure includes: corroding the sacrificial layer and forming a second extended cavity region corresponding to the second extended edge and a second cut-off cavity region corresponding to the second cut-off edge based on the second protrusion, wherein the distance from the second extended edge to the boundary of the second extended cavity region is greater than the distance from the second cut-off edge to the boundary of the second cut-off cavity region.

[0022] This application provides a bulk acoustic wave filter and a method for fabricating the same. Referring to the above description, the cavity structure includes a working region and a non-working region surrounding the working region. The working region corresponds to the overlapping region of the electrode structure and the piezoelectric layer. The electrode structure includes at least one extending edge, and the non-working region includes an extended cavity region corresponding to the extending edge. The electrode structure also includes multiple cutoff edges in addition to the at least one extending edge, and the non-working region includes a cutoff cavity region corresponding to each cutoff edge. Notably, in this application, the distance from the extending edge of the electrode structure to the extended cavity region is greater than the distance from the cutoff edge of the electrode structure to the cutoff cavity region.

[0023] In other words, because the distance from the extended edge of the electrode structure to the extended cavity region is greater than the distance from the cut-off edge of the electrode structure to the cut-off cavity region (i.e., the distance from the extended edge of the electrode structure to the extended cavity region is not equal to the distance from the cut-off edge of the electrode structure to the cut-off cavity region), a significant abrupt change in acoustic impedance is formed at the edge of the working region. That is, it is equivalent to forming a smooth air bridge structure at the extended edge of the electrode structure.

[0024] Therefore, when sound waves propagate to the edge of the working area, they encounter steep reflection boundaries (i.e., the extended cavity region) and are reflected back to the working area. This further reduces the dissipation of sound wave energy, improves the Q value, and ensures the overall performance of the bulk acoustic wave filter.

[0025] This solves the technical problem in the prior art where the electrodes extend continuously and uniformly in the non-working area, which is equivalent to eliminating impedance abrupt changes at the acoustic boundary. This causes some acoustic energy to leak to the substrate, resulting in irreversible energy dissipation, which in turn leads to a decrease in the Q value of the bulk acoustic wave filter and even affects the overall performance of the bulk acoustic wave filter.

[0026] Furthermore, this application increases the distance from the extended edge of the electrode structure to the extended cavity region while keeping the distance from the cut-off edge of the electrode structure to the cut-off cavity region unchanged, thereby enabling the bulk acoustic wave filter to be reduced as much as possible while improving the Q value of the bulk acoustic wave filter.

[0027] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments of this application in conjunction with the accompanying drawings. Attached Figure Description

[0028] The following sections will describe some specific embodiments of this application in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a top view of an existing bulk acoustic wave filter; Figure 2 This is a cross-sectional view of an existing bulk acoustic wave filter; Figure 3 This is a top view of a bulk acoustic wave filter according to an embodiment of this application; Figure 4 This is a cross-sectional view of a bulk acoustic wave filter according to an embodiment of this application; Figure 5 This is a top view of another bulk acoustic wave filter according to an embodiment of this application; Figure 6 This is a top view of yet another bulk acoustic wave filter according to an embodiment of this application; Figure 7 This is a flowchart of the method for manufacturing a bulk acoustic wave filter according to an embodiment of this application; Figure 8 This is a schematic diagram of the substrate to be removed, the upper electrode layer, the piezoelectric layer, and the lower electrode layer according to the embodiments of this application; Figure 9 This is a schematic diagram of the deposition and etching of the lower electrode layer according to the embodiments of this application; Figure 10 This is a schematic diagram of the deposition and etching of the sacrificial layer according to the embodiments of this application; Figure 11 This is a schematic diagram of the deposition of a fence layer on the second region, the third region, and the lower electrode layer according to an embodiment of this application; Figure 12 This is a schematic diagram illustrating the deposition of a carrier substrate, overall flipping, and removal of the substrate to be removed according to an embodiment of this application; Figure 13This is a schematic diagram of etching the upper electrode layer according to an embodiment of this application. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] To enable those skilled in the art to better understand the present disclosure, the technical solutions of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present disclosure.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] Figure 3 This is a top view of a bulk acoustic wave filter according to an embodiment of this application. Figure 4 This is a cross-sectional view of a bulk acoustic wave filter according to an embodiment of this application. (Reference) Figure 3 and Figure 4As shown, this application provides a bulk acoustic wave filter, including: a carrier substrate 100, a piezoelectric layer 200 deposited on the carrier substrate 100, an electrode structure 300, and a cavity structure 400 formed on the carrier substrate 100. The cavity structure 400 includes a working region 410 corresponding to the overlapping region of the electrode structure 300 and the piezoelectric layer 200, and a non-working region 420 surrounding the working region 410. The electrode structure 300 includes at least one extending edge 310 and a plurality of cutting edges 320. The non-working region 420 includes an extending cavity region 421 corresponding to the extending edge 310 and a cutting cavity region 422 corresponding to the cutting edge 320. The distance from the extending edge 310 to the boundary of the extending cavity region 421 is greater than the distance from the cutting edge 320 to the boundary of the cutting cavity region 422.

[0034] As described in the background section, for a bulk acoustic wave filter, its operating region requires a significant acoustic impedance abrupt change boundary to reflect acoustic wave energy back to the operating region, thereby forming an efficient resonance. However, since the distances from the second extension edge 312 of the upper electrode layer 340 and the first extension edge 311 of the lower electrode layer 330 to the boundary of the cavity structure 400 are equal to the distances from the other edges to the cavity structure 400, this effectively eliminates the impedance abrupt change at the acoustic boundary.

[0035] In other words, when sound waves propagate to the edge of the working region, if the electrodes extend continuously and uniformly in the non-working region, the sound waves will encounter a gradual transition from high impedance to low impedance, rather than a steep reflection boundary. This causes some sound wave energy to leak into the substrate instead of being reflected back to the working region, resulting in irreversible energy dissipation. This energy leakage directly leads to a decrease in the Q value of the bulk acoustic wave filter, thus affecting the overall performance of the bulk acoustic wave filter.

[0036] In view of this, this application provides a bulk acoustic wave filter. The bulk acoustic wave filter includes a carrier substrate 100, a piezoelectric layer 200 deposited on the carrier substrate 100, an electrode structure 300, and a cavity structure 400 formed on the carrier substrate 100. The electrode structure 300 includes a lower electrode layer 330 and an upper electrode layer 340. The cavity structure 400 includes a working region 410 corresponding to the overlapping region of the electrode structure 300 and the piezoelectric layer 200, and a non-working region 420 surrounding the working region 410.

[0037] Further, refer to Figure 3 and Figure 4As shown, the electrode structure 300 includes at least one extending edge 310 and a plurality of cutting-off edges 320. The non-working region 420 includes an extending cavity region 421 corresponding to the extending edge 310 and a cutting-off cavity region 422 corresponding to the cutting-off edges 320. Furthermore, the extending edge 310 includes a first extending edge 311 and a second extending edge 312, wherein the first extending edge 311 corresponds to a first extension portion 332 of the lower electrode layer 330, and the second extending edge 312 corresponds to a second extension portion 342 of the upper electrode layer 340, and the orthographic projections of the first extension portion 332 and the second extension portion 342 on the carrier substrate 100 are not adjacent.

[0038] In other words, because the distance from the extended edge 310 of the electrode structure 300 to the extended cavity region 421 is greater than the distance from the cutoff edge 320 of the electrode structure 300 to the cutoff cavity region 422 (i.e., the distance from the extended edge 310 of the electrode structure 300 to the extended cavity region 421 is not equal to the distance from the cutoff edge 320 of the electrode structure 300 to the cutoff cavity region 422), a significant acoustic impedance abrupt change boundary (i.e., the extended cavity region 421) is formed at the edge of the working region 410. This is equivalent to forming a smooth air bridge structure at the extended edge of the electrode structure.

[0039] Therefore, when the sound wave propagates to the edge of the working area 410, it encounters a steep reflection boundary and is reflected back to the working area 410. This further reduces the dissipation of sound wave energy, improves the Q value, and ensures the overall performance of the bulk acoustic wave filter.

[0040] This solves the technical problem in the prior art where the electrodes extend continuously and uniformly in the non-working area, which is equivalent to eliminating impedance abrupt changes at the acoustic boundary. This causes some acoustic energy to leak to the substrate, resulting in irreversible energy dissipation, which in turn leads to a decrease in the Q value of the bulk acoustic wave filter and even affects the overall performance of the bulk acoustic wave filter.

[0041] Furthermore, this application increases the distance from the extended edge of the electrode structure to the extended cavity region while keeping the distance from the cut-off edge of the electrode structure to the cut-off cavity region unchanged, thereby enabling the bulk acoustic wave filter to be reduced as much as possible while improving the Q value of the bulk acoustic wave filter.

[0042] Optionally, it includes: a fence layer 500 deposited on a carrier substrate 100, and an electrode structure 300 including a lower electrode layer 330 deposited on the fence layer 500, and the lower electrode layer 330 including a first extension edge 311 and a plurality of first cut-off edges 321, the non-working region 420 including a first extension cavity region 4211 corresponding to the first extension edge 311 and a first cut-off cavity region 4221 corresponding to the first cut-off edge 321; and the distance 333 from the first extension edge 311 to the boundary of the first extension cavity region 4211 is greater than the distance 334 from the first cut-off edge 321 to the boundary of the first cut-off cavity region 4221.

[0043] Specifically, Figure 5 This is a top view of another bulk acoustic wave filter according to an embodiment of this application. (Reference) Figure 5 As shown, since the electrode structure 300 includes a lower electrode layer 330, the extending edge 310 includes a first extending edge 311 corresponding to the lower electrode layer 330, and the cutting-off edge 320 includes a first cutting-off edge 321 corresponding to the lower electrode layer 330. Furthermore, the extending cavity region 421 includes a first extending cavity region 4211 corresponding to the first extending edge 311. The cutting-off cavity region 422 includes a first cutting-off cavity region 4221 corresponding to the first cutting-off edge 321.

[0044] That is, in Figure 5 In the bulk acoustic wave filter shown, the extended cavity region 421 only includes the first extended cavity region 4211 corresponding to the lower electrode layer 330, and does not include the second extended cavity region 4212 corresponding to the upper electrode layer 340. The second extended cavity region 4212 corresponding to the upper electrode layer 340 will be mentioned later, so it will not be described again here.

[0045] Furthermore, since the distance 333 from the first extended edge 311 to the boundary of the first extended cavity region 4211 is greater than the distance 334 from the first cut-off edge 321 to the boundary of the first cut-off cavity region 4221, a significant acoustic impedance abrupt change boundary is formed at the first extended cavity region 4211 of the first extended edge 311 of the lower electrode layer 330.

[0046] Therefore, when the sound wave propagates to the first extended cavity region 4211, the sound wave will be reflected back to the working region 410. This can further reduce the dissipation of sound wave energy, improve the Q value, and ensure the overall performance of the bulk acoustic wave filter.

[0047] Optionally, the distance 333 from the first extended edge 311 to the boundary of the first extended cavity region 4211 is 1.5 to 3 times the distance 334 from the first cut-off edge 321 to the boundary of the first cut-off cavity region 4221.

[0048] Optionally, the piezoelectric layer 200 is deposited on the fence layer 500 and the lower electrode layer 330.

[0049] Optionally, the electrode structure 300 includes an upper electrode layer 340 deposited on the piezoelectric layer 200, and the upper electrode layer 340 includes a second extending edge 312 and a plurality of second cutting-off edges 322. The non-working region 420 includes a second extending cavity region 4212 corresponding to the second extending edge 312 and a second cutting-off cavity region 4222 corresponding to the second cutting-off edge 322. The distance 343 from the second extending edge 312 to the boundary of the second extending cavity region 4212 is greater than the distance 344 from the second cutting-off edge 322 to the boundary of the second cutting-off cavity region 4222.

[0050] Specifically, Figure 6 This is a top view of yet another bulk acoustic wave filter according to an embodiment of this application. (Reference) Figure 6 As shown, since the electrode structure 300 includes an upper electrode layer 340, the extending edge 310 includes a second extending edge 312 corresponding to the upper electrode layer 340, and the cutting-off edge 320 includes a second cutting-off edge 322 corresponding to the upper electrode layer 340. Furthermore, the extending cavity region 421 includes a second extending cavity region 4212 corresponding to the second extending edge 312. The cutting-off cavity region 422 is the second cutting-off cavity region 4222 corresponding to the second cutting-off edge 322.

[0051] That is, in Figure 6 In the bulk acoustic wave filter shown, the extended cavity region 421 includes only the second extended cavity region 4212 corresponding to the upper electrode layer 340, and does not include the first extended cavity region 4211 corresponding to the lower electrode layer 330.

[0052] Furthermore, since the distance 343 from the second extended edge 312 to the boundary of the second extended cavity region 4212 is greater than the distance 344 from the second cut-off edge 322 to the boundary of the second cut-off cavity region 4222, a significant acoustic impedance abrupt change boundary is formed at the second extended cavity region 4212 of the second extended edge 312 of the upper electrode layer 340.

[0053] Therefore, when the sound wave propagates to the second extended cavity region 4212, it will be reflected back to the working region 410. This further reduces the dissipation of sound wave energy, improves the Q value, and ensures the overall performance of the bulk acoustic wave filter.

[0054] In addition, refer to Figure 4As shown, the extension edge 310 further includes a first extension edge 311 corresponding to the lower electrode layer 330 and a second extension edge 312 corresponding to the upper electrode layer 340. The cutoff edge 320 includes a first cutoff edge 321 corresponding to the lower electrode layer 330 and a second cutoff edge 322 corresponding to the upper electrode layer 340. Furthermore, the extension cavity region 421 includes a first extension cavity region 4211 corresponding to the first extension edge 311 and a second extension cavity region 4212 corresponding to the second extension edge 312. The cutoff cavity region 422 includes a first cutoff cavity region 4221 corresponding to the first cutoff edge 321 and a second cutoff cavity region 4222 corresponding to the second cutoff edge 322.

[0055] That is, in the above case, the extended cavity region 421 includes not only the first extended cavity region 4211 corresponding to the lower electrode layer 330, but also the second extended cavity region 4212 corresponding to the upper electrode layer 340.

[0056] Since the distance 333 from the first extended edge 311 to the boundary of the first extended cavity region 4211 is greater than the distance 334 from the first cutoff edge 321 to the boundary of the first cutoff cavity region 4221, a significant abrupt change in acoustic impedance is formed at the first extended cavity region 4211 of the first extended edge 311 of the lower electrode layer 330. Similarly, since the distance 343 from the second extended edge 312 to the boundary of the second extended cavity region 4212 is greater than the distance 344 from the second cutoff edge 322 to the boundary of the second cutoff cavity region 4222, a significant abrupt change in acoustic impedance is also formed at the second extended cavity region 4212 of the second extended edge 312 of the upper electrode layer 340.

[0057] Therefore, when the sound wave propagates to the first extended cavity region 4211 and the second extended cavity region 4212, the sound wave will be reflected back to the working region 410. This can further reduce the dissipation of sound wave energy, improve the Q value, and ensure the overall performance of the bulk acoustic wave filter.

[0058] Optionally, the distance from the second extending edge 312 to the boundary of the second extending cavity region 4212 is 1.5 to 3 times the distance from the second cutting edge 322 to the boundary of the second cutting-off cavity region 4222.

[0059] Optionally, the distance from the second cutoff edge 322 to the boundary of the corresponding second cutoff cavity region 4222 is greater than 0.5 μm.

[0060] According to another aspect of this application, a method for manufacturing a bulk acoustic wave filter is also provided. Figure 7 This is a flowchart illustrating the fabrication method of a bulk acoustic wave filter according to an embodiment of this application. Specifically, it includes: S702: Provides substrate 600 to be removed; S704: Deposit a piezoelectric layer 200 and an electrode structure 300 on the substrate 600 to be removed, and etch the electrode structure 300 to form a cavity structure 400, wherein the cavity structure 400 includes a working region 410 corresponding to the overlapping region of the electrode structure 300 and the piezoelectric layer 200 and a non-working region 420 surrounding the working region 410. S706: In the electrode structure 300, at least one extending edge 310 and a plurality of cutting edges 320 are formed, and the non-working region 420 forms an extending cavity region 421 corresponding to the extending edge 310 and a cutting cavity region 422 corresponding to the cutting edge 320, wherein the distance from the extending edge 310 to the boundary of the extending cavity region 421 is greater than the distance from the cutting edge 320 to the boundary of the cutting cavity region 422.

[0061] Specifically, first, a substrate 600 to be removed (S702) is provided.

[0062] Then, a piezoelectric layer 200 and an electrode structure 300 are deposited and etched on the substrate 600 to be removed, thereby forming a cavity structure 400 (S704). During the deposition and etching of the piezoelectric layer 200 and the electrode structure 300, an overlapping region exists between them. The cavity portion in the cavity structure 400 corresponding to the orthogonal projection of this overlapping region is the working region 410 of the bulk acoustic wave filter. The portion of the cavity structure 400 other than the working region 410 is the non-working region 420.

[0063] It is worth noting that the etching method of the electrode structure 300 described above can be, for example, dry etching or wet etching, and there is no limitation here.

[0064] Furthermore, during the etching of the electrode structure 300, the electrode structure 300 forms at least one extended edge 310 and a plurality of cut-off edges 320. And during the formation of the cavity structure 400, the non-working area 420 of the cavity structure 400 forms an extended cavity region 421 corresponding to the extended edge 310 and a cut-off cavity region corresponding to the cut-off edge 320 (S706).

[0065] Furthermore, when forming the extended cavity region 421 corresponding to the extended edge 310, it is necessary to ensure that the distance from the extended edge 310 to the boundary of the extended cavity region 421 is greater than the distance from the cut-off edge 320 to the boundary of the cut-off cavity region 422.

[0066] Therefore, since the distance from the extending edge 310 to the extending cavity region 421 in this application is greater than the distance from the cutting edge 320 to the cutting cavity region 422 of the electrode structure 300 (i.e., the distance from the extending edge 310 to the extending cavity region 421 of the electrode structure 300 is not equal to the distance from the cutting edge 320 to the cutting cavity region 422 of the electrode structure 300), a significant acoustic impedance abrupt change boundary is formed at the edge of the working region 410. In this embodiment, the acoustic impedance abrupt change boundary can be, for example, the extending cavity region 421.

[0067] In other words, when the sound wave propagates to the edge of the working region 410, it encounters a steep reflection boundary (i.e., the extended cavity region 421) and is reflected back to the working region 410. This further reduces the dissipation of sound wave energy, improves the Q value, and ensures the overall performance of the bulk acoustic wave filter.

[0068] This solves the technical problem in the prior art where the electrodes extend continuously and uniformly in the non-working area, which is equivalent to eliminating impedance abrupt changes at the acoustic boundary. This causes some acoustic energy to leak to the substrate, resulting in irreversible energy dissipation, which in turn leads to a decrease in the Q value of the bulk acoustic wave filter and even affects the overall performance of the bulk acoustic wave filter.

[0069] Optionally, the operation of depositing a piezoelectric layer 200 and an electrode structure 300 on the substrate 600 to be removed, and etching the electrode structure 300 to form a cavity structure 400, includes: depositing an upper electrode layer 340 on the substrate 600 to be removed, and depositing a piezoelectric layer 200 on the upper electrode layer 340; depositing and etching a lower electrode layer 330 on the piezoelectric layer 200 to form a first region 331 for exposing the piezoelectric layer 200; and depositing and etching a sacrificial layer 7 on the lower electrode layer 330 and the piezoelectric layer 200. 00, and form a second region 710 for exposing the piezoelectric layer 200 and a third region 720 for exposing the lower electrode layer 330; deposit a fence layer 500 on the second region 710, the third region 720 and the sacrificial layer 700; deposit a carrier substrate 100 on the fence layer 500, flip the whole and remove the substrate 600 to be removed; etch the upper electrode layer 340 and form a fourth region 341 for exposing the piezoelectric layer 200; and etch the sacrificial layer 700 to form a cavity structure 400.

[0070] Specifically, Figure 8 This is a schematic diagram of the substrate to be removed, the upper electrode layer, the piezoelectric layer, and the lower electrode layer according to embodiments of this application. (Reference) Figure 8 As shown, firstly, an upper electrode layer 340 is deposited on the substrate 600 to be removed, and then a piezoelectric layer 200 is deposited on the upper electrode layer 340. This forms a structure as shown in the diagram. Figure 8The structure is shown. The deposition process of the upper electrode layer 340 used in this application can be, for example, PVD or CVD, etc., and is not limited here.

[0071] Figure 9 This is a schematic diagram illustrating the deposition and etching of the lower electrode layer according to an embodiment of this application. (Reference) Figure 9 As shown, a lower electrode layer 330 is then deposited on the piezoelectric layer 200, and the lower electrode layer 330 is etched according to a pre-defined etching pattern to form a first region 331 for exposing the piezoelectric layer 200. The etching method for the lower electrode layer 330 can be, for example, dry etching, wet etching, or a lift-off process, and is not limited here. The deposition process for the lower electrode layer 330 used in this application can be, for example, PVD or CVD, and is not limited here.

[0072] Figure 10 This is a schematic diagram illustrating the deposition and etching of a sacrificial layer according to an embodiment of this application. (Reference) Figure 10 As shown, a sacrificial layer 700 is further deposited on the lower electrode layer 330 and the piezoelectric layer 200, and the sacrificial layer 700 is etched according to a pre-defined etching pattern to form a second region 710 for exposing the piezoelectric layer 200 and a third region 720 for exposing the lower electrode layer 300. The method of etching the sacrificial layer 700 can be, for example, dry etching, wet etching, or a lift-off process, and is not limited here.

[0073] It is worth noting that since the cavity structure 400 is obtained by etching the sacrificial layer 700, the shape of the etched sacrificial layer 700 actually determines the shape of the cavity structure 400 obtained subsequently. Thus, with a pre-set etching pattern, the sacrificial layer 700 can be etched based on the pre-set etching pattern to obtain the final desired cavity structure 400.

[0074] Figure 11 This is a schematic diagram illustrating the deposition of a fence layer on the second region, the third region, and the lower electrode layer according to embodiments of this application. (Reference) Figure 11 As shown, a fence layer 500 is then deposited on the second region 710, the third region 720 and the sacrificial layer 700.

[0075] Figure 12 This is a schematic diagram illustrating the deposition of a carrier substrate, overall flipping, and removal of the substrate to be removed according to an embodiment of this application. (Reference) Figure 12 As shown, after the fence layer 500 has been deposited, a carrier substrate 100 is further deposited on the fence layer 500. Then, the entire substrate 600 is flipped over and removed, thereby forming a structure as shown. Figure 12 The structure shown is shown.

[0076] Figure 13 This is a schematic diagram of the etching of the upper electrode layer according to an embodiment of this application. (Reference) Figure 13 As shown, the upper electrode layer 340 is etched using dry etching, wet etching, or photolithographic lift-off processes to form a fourth region 341 for exposing the piezoelectric layer 200. Furthermore, when etching the upper electrode layer 340 using a pre-defined etching pattern, the distance from the boundary of the orthographic projection of the upper electrode layer 340 onto the sacrificial layer 700 to the boundary of the sacrificial layer 700 is greater than 0.5 μm. Additionally, when etching the upper electrode layer 340 using a pre-defined etching pattern, the distance from the boundary of the orthographic projection of the upper electrode layer 340 onto the lower electrode layer 330 to the boundary of the lower electrode layer 330 is also greater than 0.5 μm.

[0077] Finally, the sacrificial layer 700 is corroded, forming a structure like... Figure 4 The cavity structure 400 shown is illustrated.

[0078] Optionally, the operation of depositing and etching the lower electrode layer 330 on the piezoelectric layer 200 includes: etching the lower electrode layer 330 based on a preset etching pattern to form a first extension 332; determining a first extension edge 311 corresponding to the first extension 332, and a plurality of first cut-off edges 321 other than the first extension edge 311.

[0079] Specifically, refer to Figure 5 As shown, when the extended cavity region of the bulk acoustic wave filter only includes the first extended cavity region 4211 corresponding to the lower electrode layer 330, the lower electrode layer 330 is etched based on a pre-set etching pattern to form... Figure 5 The first extension 332 is shown. Thus, when the lower electrode layer 330 is etched and the first extension 332 is formed, the first extension edge 311 in the lower electrode layer 330 corresponding to the first extension 332 can be determined.

[0080] Furthermore, given that the first extension edge 311 corresponding to the first extension portion 332 has been determined, a plurality of first cut-off edges 321 can be further determined. The first cut-off edges 321 can be, for example, other edges in the etched lower electrode layer 330 besides the first extension edge 311. Even further, the first cut-off edges 321 do not have corresponding extension portions.

[0081] Optionally, the operation of depositing and etching the sacrificial layer 700 on the lower electrode layer 330 and the piezoelectric layer 200 includes: etching the sacrificial layer 700 based on a pre-defined etching pattern to form a first protrusion corresponding to the first extended edge 311. Further optionally, the operation of etching the sacrificial layer 700 to form the cavity structure 400 includes: etching the sacrificial layer 700 and forming a first extended cavity region 4211 corresponding to the first extended edge 311 and a first cutoff cavity region 4221 corresponding to the first cutoff edge 321 based on the first protrusion, wherein the distance 333 from the first extended edge 311 to the boundary of the first extended cavity region 4211 is greater than the distance 334 from the first cutoff edge 321 to the boundary of the first cutoff cavity region 4221.

[0082] Specifically, refer to Figure 5 As shown, when the extended cavity region 421 of the bulk acoustic wave filter only includes the first extended cavity region 4211 corresponding to the lower electrode layer 330, the sacrificial layer 700 can also be etched based on a pre-set etching pattern to form a first protrusion corresponding to the first extended edge 311.

[0083] Furthermore, based on the above, since the shape of the sacrificial layer 700 is the same as the shape of the cavity region 421 generated after etching the sacrificial layer 700, when the sacrificial layer 700 is etched and a first protrusion corresponding to the first extended edge 311 is formed, the first extended cavity region 4211 corresponding to the first extended edge 311 can be formed by etching the sacrificial layer 700.

[0084] Similarly, when the sacrificial layer 700 is corroded, a first cutoff cavity region 4221 corresponding to the first cutoff edge 321 will also be formed. This ensures that the distance 333 from the first extension edge 311 to the boundary of the first extension cavity region 4221 is greater than the distance 334 from the first cutoff edge 321 to the boundary of the first cutoff cavity region 4221.

[0085] Furthermore, since the distance 333 from the first extended edge 311 to the boundary of the first extended cavity region 4211 is greater than the distance 334 from the first cut-off edge 321 to the boundary of the first cut-off cavity region 4221, a significant acoustic impedance abrupt change boundary is formed at the first extended cavity region 4211 of the first extended edge 311 of the lower electrode layer 330.

[0086] Therefore, when the sound wave propagates to the first extended cavity region 4211, the sound wave will be reflected back to the working region 410. This can further reduce the dissipation of sound wave energy, improve the Q value, and ensure the overall performance of the bulk acoustic wave filter.

[0087] Optionally, the operation of depositing and etching the sacrificial layer 700 on the lower electrode layer 330 and the piezoelectric layer 200 includes: etching the sacrificial layer 700 based on a pre-set etching pattern and forming a second protrusion corresponding to the second extension edge 312 of the upper electrode layer 340.

[0088] Specifically, refer to Figure 6 As shown, the above situation is that the extended cavity region 421 only includes the first extended cavity region 4211 corresponding to the first extended edge 311 of the lower electrode layer 330. However, for the bulk acoustic wave filter, the extended cavity region 421 may also only include the second extended cavity region 4212 corresponding to the second extended edge 312 of the upper electrode layer 340.

[0089] Therefore, under the above circumstances, the sacrificial layer 700 can be etched based on a pre-defined etching pattern to form a second protrusion corresponding to the second extension edge 312. Furthermore, as described above, since the shape of the sacrificial layer 700 is the same as the shape of the cavity region 421 generated after etching the sacrificial layer 700, when etching the sacrificial layer 700 and forming the second protrusion corresponding to the second extension edge 312, the second extension cavity region 4212 corresponding to the second extension edge 312 can be formed by etching the sacrificial layer 700. The above will be described in detail later, and therefore will not be repeated here.

[0090] Optionally, the operation of etching the upper electrode layer 340 includes: etching the upper electrode layer 340 based on a pre-defined etching pattern to form a second extension 342; determining a second extension edge 312 corresponding to the second extension 342, and a plurality of second cut-off edges 322 other than the second extension edge 312. Further optionally, the operation of etching the sacrificial layer 700 to form the cavity structure 400 includes: etching the sacrificial layer 700, and forming a second extended cavity region 4212 corresponding to the second extension edge 312 and a second cut-off cavity region 4222 corresponding to the second cut-off edge 322 based on the second protrusion, wherein the distance 343 from the second extension edge 312 to the boundary of the second extended cavity region 4212 is greater than the distance 344 from the second cut-off edge 322 to the boundary of the second cut-off cavity region 4222.

[0091] Specifically, refer to Figure 6 As shown, the upper electrode layer 340 can be etched based on a pre-defined etching pattern to form the second extension 342. Therefore, when the second extension 342 is formed, a second extension edge 312 corresponding to the second extension 342 in the upper electrode layer 340 can be further determined. Similarly, other edges in the upper electrode layer 340 besides the second extension edge 312 can be determined as second cutoff edges 322.

[0092] Furthermore, since the shape corresponding to the sacrificial layer 700 is the same as the shape of the cavity region 421 generated after etching the sacrificial layer 700, when the sacrificial layer 700 is etched and a second protrusion corresponding to the second extension edge 312 is formed, the second extension cavity region 4212 corresponding to the second extension edge 312 can be formed by etching the sacrificial layer 700.

[0093] Similarly, when the sacrificial layer 700 is corroded, a second cutoff cavity region 4222 corresponding to the second cutoff edge 322 will also be formed. This ensures that the distance 343 from the second extension edge 312 to the boundary of the second extension cavity region 4212 is greater than the distance 344 from the second cutoff edge 322 to the boundary of the second cutoff cavity region 4222.

[0094] Furthermore, since the distance 343 from the second extended edge 312 to the boundary of the second extended cavity region 4212 is greater than the distance 344 from the second cut-off edge 322 to the boundary of the second cut-off cavity region 4222, a significant acoustic impedance abrupt change boundary is formed at the second extended cavity region 4212 of the second extended edge 312 of the upper electrode layer 340.

[0095] Therefore, when the sound wave propagates to the second extended cavity region 4212, the sound wave will be reflected back to the working region 410. This can further reduce the dissipation of sound wave energy, improve the Q value, and ensure the overall performance of the bulk acoustic wave filter.

[0096] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0097] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0098] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0099] The above description is merely a preferred embodiment 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 technical scope 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 bulk acoustic wave filter, characterized in that, include: The carrier substrate (100), the piezoelectric layer (200) deposited on the carrier substrate (100) and the electrode structure (300) and the cavity structure (400) formed on the carrier substrate (100), wherein the cavity structure (400) includes a working region (410) corresponding to the overlapping region of the electrode structure (300) and the piezoelectric layer (200) and a non-working region (420) surrounding the working region (410). The electrode structure (300) includes at least one extending edge (310) and multiple cutting edges (320). The non-working area (420) includes an extending cavity region (421) corresponding to the extending edge (310) and a cutting cavity region (422) corresponding to the cutting edge (320). The distance from the extension edge (310) to the boundary of the extension cavity region (421) is greater than the distance from the cut-off edge (320) to the boundary of the cut-off cavity region (422). The electrode structure (300) includes an upper electrode layer (340) and a lower electrode layer (330). The extension edge (310) includes a first extension edge (311) and a second extension edge (312). The first extension edge (311) corresponds to a first extension (332) of the lower electrode layer (330), and the second extension edge (312) corresponds to a second extension (342) of the upper electrode layer (340). The orthographic projections of the first extension (332) and the second extension (342) on the carrier substrate (100) are not adjacent.

2. The bulk acoustic wave filter according to claim 1, characterized in that, include: A fence layer (500) is deposited on the carrier substrate (100), and the electrode structure (300) includes a lower electrode layer (330) deposited on the fence layer (500). The lower electrode layer (330) includes a plurality of first cut-off edges (321), and the non-working area (420) includes a first extended cavity region (4211) corresponding to the first extended edge (311) and a first cut-off cavity region (4221) corresponding to the first cut-off edge (321); and The distance from the first extended edge (311) to the boundary of the first extended cavity region (4211) is greater than the distance from the first cut-off edge (321) to the boundary of the first cut-off cavity region (4221).

3. The bulk acoustic wave filter according to claim 2, characterized in that, The distance from the first extended edge (311) to the boundary of the first extended cavity region (4211) is 1.5 to 3 times the distance from the first cut-off edge (321) to the boundary of the first cut-off cavity region (4221).

4. The bulk acoustic wave filter according to claim 2, characterized in that, The piezoelectric layer (200) is deposited on the fence layer (500) and the lower electrode layer (330).

5. The bulk acoustic wave filter according to claim 1 or 4, characterized in that, The electrode structure (300) includes an upper electrode layer (340) deposited on the piezoelectric layer (200), and The upper electrode layer (340) includes a plurality of second cut-off edges (322), and the non-working area (420) includes a second extended cavity region (4212) corresponding to the second extended edge (312) and a second cut-off cavity region (4222) corresponding to the second cut-off edge (322); and The distance from the second extended edge (312) to the boundary of the second extended cavity region (4212) is greater than the distance from the second cut-off edge (322) to the boundary of the second cut-off cavity region (4222).

6. The bulk acoustic wave filter according to claim 5, characterized in that, The distance from the second extended edge (312) to the boundary of the second extended cavity region (4212) is 1.5 to 3 times the distance from the second cut-off edge (322) to the boundary of the second cut-off cavity region (4222).

7. A method for manufacturing a bulk acoustic wave filter, characterized in that, include: Provide substrate to be removed (600); A piezoelectric layer (200) and an electrode structure (300) are deposited on the substrate (600) to be removed, and the electrode structure (300) is etched to form a cavity structure (400), wherein the cavity structure (400) includes a working region (410) corresponding to the overlapping region of the electrode structure (300) and the piezoelectric layer (200) and a non-working region (420) surrounding the working region (410). In the electrode structure (300), at least one extending edge (310) and a plurality of cutting edges (320) are formed, and in the non-working area (420), an extending cavity region (421) corresponding to the extending edge (310) and a cutting cavity region (422) corresponding to the cutting edge (320) are formed, wherein... The distance from the extension edge (310) to the boundary of the extension cavity region (421) is greater than the distance from the cut-off edge (320) to the boundary of the cut-off cavity region (422). The electrode structure (300) includes an upper electrode layer (340) and a lower electrode layer (330). The extension edge (310) includes a first extension edge (311) and a second extension edge (312). The first extension edge (311) corresponds to a first extension (332) of the lower electrode layer (330), and the second extension edge (312) corresponds to a second extension (342) of the upper electrode layer (340). The orthographic projections of the first extension (332) and the second extension (342) on the substrate (600) to be removed are not adjacent.

8. The method according to claim 7, characterized in that, The operation of depositing a piezoelectric layer (200) and an electrode structure (300) on the substrate (600) to be removed, and etching the electrode structure (300) to form a cavity structure (400) includes: An upper electrode layer (340) is deposited on the substrate (600) to be removed, and the piezoelectric layer (200) is deposited on the upper electrode layer (340). A lower electrode layer (330) is deposited and etched on the piezoelectric layer (200) to form a first region (331) for exposing the piezoelectric layer (200). A sacrificial layer (700) is deposited and etched on the lower electrode layer (330) and the piezoelectric layer (200) to form a second region (710) for exposing the piezoelectric layer (200) and a third region (720) for exposing the lower electrode layer (330). A fence layer (500) is deposited on the second region (710), the third region (720) and the sacrificial layer (700); A carrier substrate (100) is deposited on the fence layer (500), and the entire substrate (600) to be removed is flipped over and removed. Etch the upper electrode layer (340) and form a fourth region (341) for exposing the piezoelectric layer (200); and The sacrificial layer (700) is corroded to form the cavity structure (400).

9. The method according to claim 8, characterized in that, The operation of depositing and etching the lower electrode layer (330) on the piezoelectric layer (200) includes: The lower electrode layer (330) is etched based on a pre-defined etching pattern to form a first extension (332). A first extension edge (311) corresponding to the first extension (332) is determined, as well as a plurality of first cut-off edges (321) other than the first extension edge (311).

10. The method according to claim 9, characterized in that, The operation of depositing and etching the sacrificial layer (700) on the lower electrode layer (330) and the piezoelectric layer (200) includes: The sacrificial layer (700) is etched based on a pre-defined etching pattern to form a first protrusion corresponding to the first extended edge (311).

11. The method according to claim 10, characterized in that, The operation of eroding the sacrificial layer (700) and forming the cavity structure (400) includes: The sacrificial layer (700) is etched, and a first extended cavity region (4211) corresponding to the first extended edge (311) and a first cut-off cavity region (4221) corresponding to the first cut-off edge (321) are formed based on the first protrusion, wherein... The distance from the first extended edge (311) to the boundary of the first extended cavity region (4211) is greater than the distance from the first cut-off edge (321) to the boundary of the first cut-off cavity region (4221).

12. The method according to claim 8 or 10, characterized in that, The operation of depositing and etching the sacrificial layer (700) on the lower electrode layer (330) and the piezoelectric layer (200) includes: The sacrificial layer (700) is etched based on a pre-defined etching pattern to form a second protrusion corresponding to the second extension edge (312) of the upper electrode layer (340).

13. The method according to claim 12, characterized in that, The operation of etching the upper electrode layer (340) includes: The upper electrode layer (340) is etched based on a pre-defined etching pattern to form a second extension (342). Determine the second extension edge (312) corresponding to the second extension (342), and a plurality of second cut-off edges (322) other than the second extension edge (312).

14. The method according to claim 13, characterized in that, The operation of eroding the sacrificial layer (700) and forming the cavity structure (400) includes: The sacrificial layer (700) is etched, and a second extended cavity region (4212) corresponding to the second extended edge (312) and a second cut-off cavity region (4222) corresponding to the second cut-off edge (322) are formed based on the second protrusion, wherein... The distance from the second extended edge (312) to the boundary of the second extended cavity region (4212) is greater than the distance from the second cut-off edge (322) to the boundary of the second cut-off cavity region (4222).

Images