A filter and a method for manufacturing a filter

Abstract

The application provides a filter and a preparation method of the filter. The filter comprises a substrate and at least two test electrodes. The surface of the substrate is provided with at least one resonator. The resonator comprises a bottom electrode, a piezoelectric layer and a top electrode. The at least one test electrode at least partially overlaps the bottom electrode in the orthographic projection of the substrate, and at the same time, the test electrode at least partially overlaps the top electrode in the orthographic projection of the substrate. The bottom electrode and the top electrode obtain electrical signals through different test electrodes. The technical scheme provided by the application reduces the planar size of the filter.

Description

Technical Field

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

[0002] Film Bulk Acoustic Resonators (FBARs) play an important role in the field of communication as an important member of piezoelectric devices. Filters composed of FBARs have excellent characteristics such as small size, high resonant frequency, high quality factor, large power capacity and good roll-off effect.

[0003] The main structure of the thin-film bulk acoustic resonator is a "sandwich" structure consisting of a bottom electrode, a piezoelectric layer, and a top electrode, that is, a piezoelectric material sandwiched between two metal electrodes; the bottom electrode and the top electrode acquire electrical signals through different test electrodes.

[0004] However, in existing technologies, the test electrode and the resonator are placed on the same plane, see [reference needed]. Figure 1 , Figure 1 This is a top view of a filter in the prior art. The test electrode 20 and the resonator 10 are both located on the surface of the substrate 001. That is, the orthographic projection of the test electrode 20 on the substrate 001 does not overlap with the orthographic projection of the resonator 10 on the substrate 001. The test electrode 20 is connected to the electrode of the resonator 10 through the welding part 20a. The planar size of the filter is relatively large. Moreover, due to the requirements of electrical performance testing, the test electrode 20 needs to be made into a relatively large area to facilitate good contact during testing. This results in the test electrode 20 occupying a large proportion of the overall area of ​​the filter, which to some extent increases the volume of the filter. Summary of the Invention

[0005] This application provides a filter and a method for fabricating the filter to reduce the planar size of the filter.

[0006] This application provides a filter, including:

[0007] A substrate, wherein at least one resonator is disposed on the surface of the substrate, the resonator comprising a stack of a bottom electrode, a piezoelectric layer and a top electrode;

[0008] At least two test electrodes are provided, wherein at least one of the test electrodes at least partially overlaps with the bottom electrode in the orthographic projection on the substrate, and at least partially overlaps with the top electrode in the orthographic projection on the substrate, wherein the bottom electrode and the top electrode acquire electrical signals through different test electrodes.

[0009] Optionally, the test electrode includes a connecting support section and a test electrode cap, a first end of the connecting support section is connected to the bottom electrode or the top electrode, a second end of the connecting support section is set higher than the top electrode, and the connecting support section is used to support the test electrode cap;

[0010] The test electrode cap extends toward the effective region of the resonator.

[0011] Optionally, the cross-sectional area of ​​the test electrode cap in the plane of the substrate is greater than the cross-sectional area of ​​the connecting support segment in the plane of the substrate.

[0012] Optionally, the test electrode includes a first test electrode and a second test electrode;

[0013] The first test electrode includes a first connecting support section and a first test electrode cap, wherein a first end of the first connecting support section is connected to the bottom electrode;

[0014] The second test electrode includes a second connecting support section and a second test electrode cap, with the first end of the second connecting support section connected to the top electrode.

[0015] Optionally, the first test electrode is disposed on the bottom electrode, and the second test electrode is disposed on the top electrode; the first connecting support segment passes through the through hole located in the piezoelectric layer and is connected to the bottom electrode.

[0016] Optionally, the first test electrode and the second test electrode are disposed on the bottom electrode, or the first test electrode and the second test electrode are disposed on the top electrode.

[0017] Optionally, the bottom electrode includes a first part bottom electrode, a second part bottom electrode, and a third part bottom electrode. The first part bottom electrode and the second part bottom electrode are insulated from each other, and the third part bottom electrode is insulated from the second part bottom electrode. The first part bottom electrode and the third part bottom electrode are connected.

[0018] The first connecting support segment passes through a through-hole located in the piezoelectric layer and connects to the first portion of the bottom electrode;

[0019] The second connecting support segment passes through a through-hole located in the piezoelectric layer and connects to the second portion of the bottom electrode;

[0020] The filter further includes a first conductive connection portion, a first end of which is connected to the second bottom electrode portion, and a second end of which passes through a through-hole located in the piezoelectric layer and is connected to the top electrode portion.

[0021] Optionally, the top electrode includes a first part of the top electrode and a second part of the top electrode, wherein the first part of the top electrode and the second part of the top electrode are insulated from each other.

[0022] The first connecting support segment is connected to the first part of the top electrode;

[0023] The second connecting support segment is connected to the second part of the top electrode;

[0024] The filter further includes a second conductive connection portion, the first end of which is connected to the first portion of the top electrode, and the second end of which is connected to the bottom electrode.

[0025] This application also provides a method for fabricating a filter, comprising:

[0026] Provide substrate;

[0027] A stack of a bottom electrode, a piezoelectric layer, and a top electrode is sequentially formed on the surface of the substrate to form at least one resonator on the surface of the substrate.

[0028] At least two test electrodes are formed, and at least one of the test electrodes overlaps at least partially with the orthographic projection of the bottom electrode onto the substrate, and also overlaps at least partially with the orthographic projection of the top electrode onto the substrate. The bottom electrode and the top electrode acquire electrical signals through different test electrodes.

[0029] Optionally, the test electrode includes a connecting support section and a test electrode cap, forming at least two test electrodes, including:

[0030] Photoresist is formed on the surface of the substrate and the surface of the resonator;

[0031] The photoresist is subjected to a first photolithography process to expose and develop a first patterned area of ​​the photoresist, which is the area corresponding to the test electrode cap.

[0032] A second photolithography process is performed on the photoresist to expose and develop a second patterned region of the photoresist, which is the region corresponding to the connecting support segment.

[0033] The conductive layer containing the deposition test electrode;

[0034] The photoresist is stripped to form the test electrode.

[0035] In the filter provided in this embodiment, at least one test electrode and the bottom electrode at least partially overlap in their orthogonal projections on the substrate, and the test electrode also at least partially overlaps in their orthogonal projections on the top electrode on the substrate. That is, the test electrode is disposed on the resonator. Compared with the prior art, where the test electrode and the resonator are located on the same plane, the placement of the test electrode does not increase the size of the filter on the plane where the substrate is located. Therefore, the technical solution of this application reduces the planar size of the filter.

[0036] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0038] Figure 1 This is a top view of a filter in the prior art;

[0039] Figure 2 This is a top view of a filter provided in this application;

[0040] Figure 3 This is a schematic diagram of the structure of the first type of filter provided in this application;

[0041] Figure 4 This is a schematic diagram of the structure of the second type of filter provided in this application;

[0042] Figure 5 This is a schematic diagram of the structure of the third type of filter provided in this application;

[0043] Figure 6 The structural diagram of the fourth type of filter provided in this application;

[0044] Figure 7 This is a schematic diagram of the structure of the fifth type of filter provided in this application;

[0045] Figure 8 This is a schematic flowchart of a filter fabrication method provided in this application;

[0046] Figures 9-10 This is a schematic diagram of the structure corresponding to each step of the filter fabrication method provided in this application;

[0047] Figure 11 yes Figure 8 A flowchart of the S130 process;

[0048] Figures 12-16 yes Figure 8 A schematic diagram of the structure corresponding to each step in S130. Detailed Implementation

[0049] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0050] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that includes a series of steps or apparatuses is not necessarily limited to those explicitly listed, but may include other steps or apparatuses not explicitly listed or inherent to such processes, methods, products, or apparatuses.

[0051] To reduce the planar dimensions and volume of the filter, this application provides a new technical solution, which is described in detail below.

[0052] See Figures 2 to 4 , Figure 2 This is a top view of a filter provided in this application. Figure 3 This is a schematic diagram of the structure of the first type of filter provided in this application. Figure 4 This is a schematic diagram of the structure of the second type of filter provided in this application. The filter includes: a substrate 001, a resonator 10, and at least two test electrodes 20.

[0053] At least one resonator 10 is disposed on the upper surface of the substrate 001. The resonator 10 includes a stack of bottom electrode 11, piezoelectric layer 12 and top electrode 13, that is, the substrate 001, bottom electrode 11, piezoelectric layer 12 and top electrode 13 are disposed sequentially in the thickness direction of the filter.

[0054] At least one test electrode 20 at least partially overlaps with the orthographic projection of the bottom electrode 11 onto the substrate 001, and the test electrode 20 also at least partially overlaps with the orthographic projection of the top electrode 13 onto the substrate 001; the bottom electrode 11 and the top electrode 13 acquire electrical signals through different test electrodes 20. For example, as... Figure 3 and Figure 4 As shown, Figure 3 and Figure 4 Only one test electrode 20 is shown, in which, Figure 3 The image shows a test electrode 20 connected to the bottom electrode 11, through which the bottom electrode 11 acquires electrical signals. Figure 4 The diagram shows a test electrode 20 connected to the top electrode 13, through which the top electrode 13 acquires electrical signals.

[0055] In one implementation, such as Figure 3 As shown, the orthogonal projection of the test electrode 20 onto the substrate 001 is entirely within the orthogonal projection of the bottom electrode 11 onto the substrate 001, and the orthogonal projection of the test electrode 20 onto the substrate 001 also partially overlaps with the orthogonal projection of the top electrode 13 onto the substrate 001.

[0056] In another embodiment, such as Figure 4 As shown, the orthogonal projection of the test electrode 20 onto the substrate 001 is entirely within the orthogonal projection of the top electrode 13 onto the substrate 001, and the orthogonal projection of the test electrode 20 onto the substrate 001 is entirely within the orthogonal projection of the bottom electrode 11 onto the substrate 001.

[0057] In the filter provided in this embodiment, at least one test electrode 20 and the bottom electrode 11 at least partially overlap in their orthogonal projections on the substrate 001, while the test electrode 20 also at least partially overlaps in their orthogonal projections on the top electrode 13 on the substrate 001. That is, the test electrode 20 is disposed on the resonator 10. Compared with the prior art, where the test electrode 20 and the resonator 10 are located on the same plane, the placement of the test electrode 20 does not increase the size of the filter on the plane where the substrate 001 is located. Therefore, the technical solution of this application reduces the planar size of the filter.

[0058] Optionally, based on the above technical solutions, such as Figure 3 As shown, the test electrode 20 includes a connecting support section 21 and a test electrode cap 22. The connecting support section 21 is used to support the test electrode cap 22. The test electrode cap 22 extends toward the effective area of ​​the resonator 10. Figure 3 The first end of the connecting support section 21 is shown to be connected to the bottom electrode 11. The first end is the end of the connecting support section 21 that is away from the test electrode cap 22.

[0059] It should be noted that the effective region of the resonator 10 is the overlapping region of the bottom electrode 11, the piezoelectric layer 12, the top electrode 13, and the acoustic reflection structure (exemplarily, in this embodiment, the acoustic reflection structure is an air cavity 1a) projected onto the substrate 001. Figure 3 As shown, the orthographic projection of the test electrode cap 22 on the substrate 001 overlaps with the orthographic projection of the top electrode 13 on the substrate 001, for example: Figure 3 As shown, the horizontal distance between the edge of the test electrode cap 22 and the edge of the top electrode 13 is d. The specific value of d can be set according to the specific application requirements, and this embodiment does not limit it.

[0060] In this application, the second end of the connecting support section 21 is positioned higher than the top electrode 13 and is used to support the test electrode cap 22. That is, the test electrode cap 22 does not contact the piezoelectric layer 12. In the test electrode 20, only the connecting support section 21 contacts the piezoelectric layer 12, which greatly reduces the contact area between the test electrode 20 and the piezoelectric layer 12, reduces the leakage of sound waves, thereby reducing the energy loss of the filter and improving the filtering performance of the filter.

[0061] Furthermore, in this application, only the connecting support segment 21 of the test electrode 20 contacts the piezoelectric layer 12, and the contact probe (not shown in the figure) that applies the electrical signal directly contacts the test electrode cap 22. This effectively reduces the contact area between the test electrode 20 and the resonator 10. By setting the test electrode cap 22 to a preset area, while ensuring that the contact probe and the test electrode 20 have a preset contact resistance (for example, within 1 ohm), the proportion of the test electrode 20 in the overall area of ​​the filter can be reduced to a certain extent, thereby reducing the size of the filter. Further, to ensure that the contact probe and the test electrode 20 have a preset contact resistance, the area of ​​the test electrode cap 22 can be set within a preset area range. Since the test electrode cap 22 extends towards the effective area of ​​the resonator 10, increasing the area of ​​the test electrode cap 22 will not increase the horizontal dimension of the filter. Understandably, the extent to which the test electrode cap 22 extends towards the effective area of ​​the resonator 10 can be specifically limited according to actual conditions.

[0062] Optionally, based on the above technical solutions, such as Figure 4 As shown, the test electrode 20 includes a connecting support section 21 and a test electrode cap 22. The connecting support section 21 is used to support the test electrode cap 22. The test electrode cap 22 extends toward the effective area of ​​the resonator 10. Figure 4 The first end of the connecting support section 21 is connected to the top electrode 23. The second end of the connecting support section 21 is spaced apart from the upper surface of the top electrode 13 in the thickness direction. That is, the second end of the connecting support section 21 is set higher than the top electrode 13. The second end is the end of the connecting support section 21 that is close to the test electrode cap 22.

[0063] It should be noted that the effective area of ​​the resonator 10 is the overlapping area of ​​the bottom electrode 11, the piezoelectric layer 12, the top electrode 13, and the acoustic reflection structure (exemplarily, in this embodiment, the acoustic reflection structure is the air cavity 1a) on the substrate 001.

[0064] In this application, the orthogonal projection of the test electrode 20 onto the substrate 001 is entirely within the orthogonal projection of the top electrode 13 onto the substrate 001, and the orthogonal projection of the test electrode 20 onto the substrate 001 is entirely within the orthogonal projection of the bottom electrode 11 onto the substrate 001.

[0065] Furthermore, in this application, the contact probe (not shown in the figure) that applies the electrical signal directly contacts the test electrode cap 22, which is equivalent to reducing the contact area between the test electrode 20 and the resonator 10. By setting the test electrode cap 22 to a preset area, while ensuring that the contact probe and the test electrode 20 have a preset contact resistance (for example, within 1 ohm), the proportion of the test electrode 20 in the overall area of ​​the filter can be reduced to a certain extent, thereby reducing the size of the filter. To ensure that the contact probe and the test electrode 20 have a preset contact resistance, the area of ​​the test electrode cap 22 can be set within a preset area range. Since the test electrode cap 22 extends toward the effective area of ​​the resonator 10, increasing the area of ​​the test electrode cap 22 will not increase the horizontal size of the filter. Understandably, the extent to which the test electrode cap 22 extends toward the effective area of ​​the resonator 10 can be specifically limited according to the actual situation.

[0066] Optionally, based on the above technical solutions, see [reference needed]. Figure 3 and Figure 4 The cross-sectional area of ​​the test electrode cap 22 on the plane of the substrate 001 is greater than the cross-sectional area of ​​the connecting support section 21 on the plane of the substrate 001. The specific shape of the test electrode cap 22 and the specific shape of the connecting support section 21 are not specifically limited in this application. For example, the cross-sectional shape of the test electrode cap 22 on the plane of the substrate 001 can be any one of a circle, an ellipse, and a square.

[0067] In this application, the contact probe that applies the electrical signal directly contacts the test electrode cap 22. Since the cross-sectional area of ​​the test electrode cap 22 on the plane of substrate 001 is larger than the cross-sectional area of ​​the connecting support section 21 on the plane of substrate 001, this ensures that the contact probe and test electrode 20 have a preset contact resistance, thus meeting the requirements for filter electrical performance testing. Furthermore, it reduces the contact area between the test electrode 20 and resonator 10, thereby reducing the size of the filter. See also [link to relevant documentation] in this application. Figures 5-7 , Figure 5 This is a schematic diagram of the structure of the third type of filter provided in this application. Figure 6 The structural diagram of the fourth type of filter provided in this application Figure 7 This is a schematic diagram of the structure of the fifth type of filter provided in this application. The test electrode 20 includes a first test electrode 201 and a second test electrode 202. The first test electrode 201 includes a first connecting support section 210 and a first test electrode cap 220. The first end of the first connecting support section 210 is connected to the bottom electrode 11, and the first end of the first connecting support section 210 is the end of the first connecting support section 210 away from the first test electrode cap 220 (i.e., the lower end of the first connecting support section 210). The second test electrode 202 includes a second connecting support section 211 and a second test electrode cap 221. The first end of the second connecting support section 211 is connected to the top electrode 13, and the first end of the second connecting support section 211 is the end of the second connecting support section 211 away from the second test electrode cap 221 (i.e., the lower end of the second connecting support section 211).

[0068] Understandably, the bottom electrode 11 and top electrode 13 of the resonator 10 acquire electrical signals through different test electrodes 20. In this application, the bottom electrode 11 acquires electrical signals through the first test electrode 201, and the top electrode 13 acquires electrical signals through the second test electrode 202.

[0069] Regarding the positioning of the first test electrode 201 and the second test electrode 202, the following technical solution is provided in this application:

[0070] In one embodiment, based on the above technical solution, see [reference needed]. Figure 5 The first test electrode 201 is disposed on the bottom electrode 11, and the second test electrode 202 is disposed on the top electrode 13, which can reduce the interference between the electrical signals of the bottom electrode 11 and the top electrode 13. It should be noted that the specific shape of the top electrode 13 is not limited in this application.

[0071] Furthermore, the first connecting support segment 210 passes through the through-hole in the piezoelectric layer 12 and connects to the bottom electrode 11. This allows the first test electrode 201 to be connected to the bottom electrode 11 only through the first connecting support segment 210, eliminating the need for the first test electrode cap 220 to contact the resonator 10. This significantly reduces the area of ​​the portion of the test electrode 20 that contacts the piezoelectric layer 12, reducing acoustic wave leakage and thus lowering the filter's energy loss and improving its filtering performance. Moreover, by setting the test electrode cap 22 to a preset area, while ensuring a preset contact resistance between the contact probe and the test electrode 20, the increased area of ​​the test electrode cap 22, extending towards the effective area of ​​the resonator 10, does not increase the horizontal dimension of the filter. This can reduce the proportion of the test electrode 20 in the overall area of ​​the filter to a certain extent, thereby reducing the filter's volume.

[0072] In another embodiment, based on the above technical solution, see [link to relevant documentation]. Figure 6 The first test electrode 201 and the second test electrode 202 are disposed on the bottom electrode 11, which allows the second test electrode 202 to be fabricated at the same time as the first test electrode 201, simplifying the fabrication process of the filter and reducing the fabrication cost of the filter.

[0073] Furthermore, such as Figure 6 As shown, the first test electrode 201 and the second test electrode 202 are disposed on the bottom electrode 11. The bottom electrode 11 includes a first part bottom electrode 110, a second part bottom electrode 111, and a third part bottom electrode 112. The first part bottom electrode 110 and the second part bottom electrode 111 are insulated from each other, and the third part bottom electrode 112 and the second part bottom electrode 111 are also insulated from each other. The first part bottom electrode 111 and the third part bottom electrode 112 are connected. A first connecting support segment 210 passes through a through-hole located in the piezoelectric layer 12 and is connected to the first part bottom electrode 110. A second connecting support segment 211 passes through a through-hole located in the piezoelectric layer 12 and is connected to the second part bottom electrode 111. The orthographic projection of the second test electrode cap 221 on the substrate 001 overlaps with the orthographic projection of the top electrode 13 on the substrate 001.

[0074] The filter also includes a first conductive connection portion 30, the first end of which is connected to the second part of the bottom electrode 111, and the second end of which is connected to the top electrode 13.

[0075] For example, such as Figure 6 As shown, the first part of the bottom electrode 110 and the second part of the bottom electrode 111 are insulated from each other by the piezoelectric layer 12, and the third part of the bottom electrode 112 is also insulated from the second part of the bottom electrode 111. In other embodiments, other insulating materials can also be used to achieve the insulation between the first part of the bottom electrode 110 and the second part of the bottom electrode 111, as well as the insulation between the third part of the bottom electrode 112 and the second part of the bottom electrode 111. For example, after fabricating the first part of the bottom electrode 110, the second part of the bottom electrode 111, and the third part of the bottom electrode 112, insulating material is first filled into the gaps between the first part of the bottom electrode 110 and the second part of the bottom electrode 111, and between the second part of the bottom electrode 111 and the third part of the bottom electrode 112, before fabricating the piezoelectric layer 12.

[0076] For example, the first conductive connection portion 30 includes a conductive via 31 located in the piezoelectric layer 12 and a conductive lead 32 located outside the piezoelectric layer 12.

[0077] In this application, the first test electrode 201 and the second test electrode 202 are disposed on the bottom electrode 11. The second connection support section 211 and the second test electrode cap 221 can be fabricated simultaneously with the fabrication of the first connection support section 210 and the first test electrode cap 220, which simplifies the fabrication process of the filter and reduces the fabrication cost of the filter.

[0078] In yet another embodiment, based on the above technical solution, see [link to relevant documentation]. Figure 7 The first test electrode 201 and the second test electrode 202 are disposed on the top electrode 13, which allows the second test electrode 202 to be fabricated at the same time as the first test electrode 201, simplifying the fabrication process of the filter and reducing the fabrication cost of the filter.

[0079] Furthermore, such as Figure 7 As shown, the top electrode 13 includes a first part top electrode 130 and a second part top electrode 131, which are insulated from each other; a first connecting support section 210 is connected to the first part top electrode 130; and a second connecting support section 211 is connected to the second part top electrode 131.

[0080] The filter also includes a second conductive connection portion 40, the first end of which is connected to the first part of the top electrode 130, and the second end of which is connected to the bottom electrode 11.

[0081] For example, such as Figure 7 As shown, the first part of the top electrode 130 and the second part of the top electrode 131 are insulated from each other by the piezoelectric layer 12. In other embodiments, insulation between the first part of the top electrode 130 and the second part of the top electrode 131 can also be achieved by other insulating materials.

[0082] For example, the second conductive connection portion 40 is a conductive through hole located inside the piezoelectric layer 12.

[0083] This application also provides a method for fabricating a filter. See [link to application]. Figure 8 , Figure 8 This is a schematic flowchart illustrating a method for fabricating a filter provided in this application. Figure 6 The filter fabrication method is illustrated using the structure shown as an example. The method includes the following steps:

[0084] S110: Provides a substrate.

[0085] See Figure 9 A substrate 001 is provided. For example, in order to improve the performance of the filter, a cavity structure 1a is provided in the substrate 001 as an acoustic reflection structure.

[0086] S120: A stack of bottom electrode, piezoelectric layer and top electrode is sequentially formed on the surface of the substrate to form at least one resonator on the surface of the substrate.

[0087] See Figure 10 A bottom electrode 11, a piezoelectric layer 12, and a top electrode 13 are sequentially formed on the surface of the substrate 001 through a coating process to form at least one resonator 10 on the surface of the substrate 001.

[0088] It should be noted that the bottom electrode 11 and top electrode 13 of the resonator 10 acquire electrical signals through different test electrodes 20; in this application, the bottom electrode 11 acquires electrical signals through the first test electrode 201, and the top electrode 13 acquires electrical signals through the second test electrode 202. Regarding the positional arrangement of the first test electrode 201 and the second test electrode 202, the first test electrode 201 and the second test electrode 202 can be arranged as follows: Figure 5 As shown, the electrodes can be set on different electrodes, or as... Figure 6 and Figure 7 As shown, they are disposed on the same electrode. In the filter fabrication method provided in this application, using... Figure 6 Taking the example where both the first test electrode 201 and the second test electrode 202 are located on the bottom electrode 11, the bottom electrode 11 needs to be patterned before forming the two test electrodes 20. This patterning process creates a bottom electrode 11 comprising a first part 110, a second part 111, and a third part 112. The first part 110 and the second part 111 are insulated from each other, as are the third part 112 and the second part 111. The first part 111 and the third part 112 are connected. Before forming the two test electrodes 20, a first through-hole T1, a second through-hole T2, and a third through-hole T3 need to be formed on the piezoelectric layer 12 using a patterning process.

[0089] S130: At least two test electrodes are formed, at least one of which overlaps at least partially with the orthogonal projection of the bottom electrode onto the substrate, and also overlaps at least partially with the orthogonal projection of the top electrode onto the substrate. The bottom electrode and the top electrode acquire electrical signals through different test electrodes.

[0090] See Figure 6A first test electrode 201, a second test electrode 202, and a first conductive connection portion 30 are formed. The first test electrode 201 and the second test electrode 202 are disposed on the bottom electrode 11. The bottom electrode 11 includes a first part bottom electrode 110, a second part bottom electrode 111, and a third part bottom electrode 112. The first part bottom electrode 110 and the second part bottom electrode 111 are insulated from each other, and the third part bottom electrode 112 and the second part bottom electrode 111 are insulated from each other. The first part bottom electrode 111 and the third part bottom electrode 112 are connected. A first connecting support segment 210 passes through a through hole located in the piezoelectric layer 12 and connects to the first part bottom electrode 110. A second connecting support segment 211 passes through a through hole located in the piezoelectric layer 12 and connects to the second part bottom electrode 111. The first end of the first conductive connection portion 30 is connected to the second part bottom electrode 111, and the second end of the first conductive connection portion 30 is connected to the top electrode 13. For example, the first conductive connection portion 30 includes a conductive via 31 located in the piezoelectric layer 12 and a conductive lead 32 located outside the piezoelectric layer 12. The orthographic projection of the second test electrode cap 221 onto the substrate 001 overlaps with the orthographic projection of the top electrode 13 onto the substrate 001. The bottom electrode 11 and the top electrode 13 acquire electrical signals through the test electrode 20. Specifically, the bottom electrode 11 acquires electrical signals through the first test electrode 201, and the top electrode 13 acquires electrical signals through the second test electrode 202.

[0091] In the filter provided in this embodiment, at least one test electrode 20 and the bottom electrode 11 at least partially overlap in their orthogonal projections on the substrate 001, while the test electrode 20 also at least partially overlaps in their orthogonal projections on the top electrode 13 on the substrate 001. That is, the test electrode 20 is disposed on the resonator 10. Compared with the prior art, where the test electrode 20 and the resonator 10 are located on the same plane, the placement of the test electrode 20 does not increase the size of the filter on the plane where the substrate 001 is located. Therefore, the technical solution of this application reduces the planar size of the filter.

[0092] Optionally, based on the above technical solutions, see [reference needed]. Figure 11 , Figure 11 yes Figure 8 The process diagram of S130 shows that the S130 test electrode includes a connecting support section and a test electrode cap. The steps to form at least two test electrodes include:

[0093] S1301: Photoresist is formed on the surface of the resonator.

[0094] See Figure 12 Before forming the photoresist 50, a conductive material is first formed within the third via T3 to form the conductive via 31 located in the piezoelectric layer 12 within the first conductive connection portion 30. See below. Figure 13 Photoresist 50 is formed on the surface of resonator 10 by spin coating.

[0095] S1302: Perform the first photolithography on the photoresist, expose and develop the first pattern area of ​​the photoresist, which is the area corresponding to the test electrode cap.

[0096] S1303: Perform a second photolithography on the photoresist, expose and develop the second patterned area of ​​the photoresist, which is the area corresponding to the connecting support segment.

[0097] See Figure 14 After two photolithography processes, the areas corresponding to the test electrode cap 22 (the first test electrode cap 220 and the second test electrode cap 221 in the figure) and the areas corresponding to the connecting support section 21 (the first connecting support section 210 and the second connecting support section 211 in the figure) are exposed and developed.

[0098] S1304: The conductive layer where the deposition test electrode is located.

[0099] See Figure 15 A conductive layer (not shown in the figure) containing the test electrode 20 (the first test electrode 201 and the second test electrode 202 in the figure) is deposited on the above structure.

[0100] S1305: Strip the photoresist to form the test electrode.

[0101] See Figure 6 and Figure 16 The photoresist 50 is stripped to form the first test electrode 201 and the second test electrode 202; then, a conductive lead 32 connected to the conductive via 31 is formed outside the piezoelectric layer 12 to form the first conductive connection portion 30.

[0102] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0103] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A filter, characterized in that, include: A substrate, wherein at least one resonator is disposed on the surface of the substrate, the resonator comprising a stack of a bottom electrode, a piezoelectric layer and a top electrode; At least two test electrodes, at least one of the test electrodes at least partially overlaps with the bottom electrode in the orthographic projection on the substrate, and at least partially overlaps with the top electrode in the orthographic projection on the substrate, wherein the bottom electrode and the top electrode acquire electrical signals through different test electrodes; The test electrode includes a connecting support section and a test electrode cap. The first end of the connecting support section is connected to the bottom electrode or the top electrode, the second end of the connecting support section is set higher than the top electrode, and the connecting support section is used to support the test electrode cap. The test electrode cap extends toward the effective region of the resonator.

2. The filter according to claim 1, characterized in that, The cross-sectional area of ​​the test electrode cap in the plane of the substrate is greater than the cross-sectional area of ​​the connecting support segment in the plane of the substrate.

3. The filter according to claim 1, characterized in that, The test electrode includes a first test electrode and a second test electrode; The first test electrode includes a first connecting support section and a first test electrode cap, wherein a first end of the first connecting support section is connected to the bottom electrode; The second test electrode includes a second connecting support section and a second test electrode cap, with the first end of the second connecting support section connected to the top electrode.

4. The filter according to claim 3, characterized in that, The first test electrode is disposed on the bottom electrode, and the second test electrode is disposed on the top electrode; the first connecting support segment passes through the through hole located in the piezoelectric layer and is connected to the bottom electrode.

5. The filter according to claim 3, characterized in that, The first test electrode and the second test electrode are disposed on the bottom electrode, or the first test electrode and the second test electrode are disposed on the top electrode.

6. The filter according to claim 5, characterized in that, The bottom electrode includes a first part bottom electrode, a second part bottom electrode, and a third part bottom electrode. The first part bottom electrode and the second part bottom electrode are insulated from each other, and the third part bottom electrode is insulated from the second part bottom electrode. The first part bottom electrode and the third part bottom electrode are connected. The first connecting support segment passes through a through-hole located in the piezoelectric layer and connects to the first portion of the bottom electrode; The second connecting support segment passes through a through-hole located in the piezoelectric layer and connects to the second portion of the bottom electrode; The filter further includes a first conductive connection portion, a first end of which is connected to the second bottom electrode portion, and a second end of which passes through a through-hole located in the piezoelectric layer and is connected to the top electrode portion.

7. The filter according to claim 5, characterized in that, The top electrode includes a first part of the top electrode and a second part of the top electrode, and the first part of the top electrode and the second part of the top electrode are insulated from each other. The first connecting support segment is connected to the first part of the top electrode; The second connecting support segment is connected to the second part of the top electrode; The filter further includes a second conductive connection portion, the first end of which is connected to the first portion of the top electrode, and the second end of which is connected to the bottom electrode.

8. A method for fabricating a filter, used to fabricate the filter as described in any one of claims 1-7, characterized in that, include: Provide substrate; A stack of a bottom electrode, a piezoelectric layer, and a top electrode is sequentially formed on the surface of the substrate to form at least one resonator on the surface of the substrate. At least two test electrodes are formed, and at least one of the test electrodes overlaps at least partially with the orthographic projection of the bottom electrode onto the substrate, and also overlaps at least partially with the orthographic projection of the top electrode onto the substrate. The bottom electrode and the top electrode acquire electrical signals through different test electrodes.

9. The method for fabricating a filter according to claim 8, characterized in that, The test electrode includes a connecting support section and a test electrode cap, forming at least two test electrodes, including: Photoresist is formed on the surface of the resonator; The photoresist is subjected to a first photolithography process to expose and develop a first patterned area of ​​the photoresist, which is the area corresponding to the test electrode cap. A second photolithography process is performed on the photoresist to expose and develop a second patterned region of the photoresist, which is the region corresponding to the connecting support segment. The conductive layer containing the deposition test electrode; The photoresist is stripped to form the test electrode.

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