Method for manufacturing filter and filter

Abstract

The invention discloses a filter manufacturing method and a filter, and the manufacturing method comprises the steps: providing a substrate, manufacturing a piezoelectric layer covering the surface of the substrate on the surface of one side of the substrate, and carrying out the etching of the piezoelectric layer, so as to form a piezoelectric body; manufacturing an electrode layer, wherein the electrode layer coats the piezoelectric body and covers the residual surface of the substrate; etching the electrode layer to form a first electrode and a second electrode which are located on the two sides of the piezoelectric body, manufacturing an air ring structure between the first electrode and the piezoelectric body, and manufacturing another air ring structure between the second electrode and the piezoelectric body; manufacturing a shell structure, and covering and fixing the shell structure above the substrate to form a cavity for accommodating the piezoelectric sensing structure; an electric connection structure is manufactured, the electric connection structure comprises a first electric connection piece and a second electric connection piece, the first electric connection piece is electrically connected with the first electrode, the second electric connection piece is electrically connected with the second electrode, and at least part of the first electric connection piece and at least part of the second electric connection piece are located outside the cavity.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and in particular to a manufacturing method of a filter and a filter. Background Art

[0002] The filter can use surface acoustic wave devices to achieve filtering. The existing filters basically use a longitudinal sandwich structure. However, during the production process of such a filter, the upper and lower electrodes require two photolithography processes, and another wafer bonding is required to make the upper cavity, which makes the filter processing technology more complicated. Summary of the invention

[0003] The present invention provides a manufacturing method of a filter and a filter, aiming to effectively solve the technical problem that the processing technology of the filter is relatively complicated in the prior art.

[0004] According to a first aspect of the present invention, the present invention provides a method for manufacturing a filter, comprising:

[0005] A substrate is provided, a piezoelectric layer covering the surface of the substrate is made on one side surface of the substrate, and the piezoelectric layer is etched to form a piezoelectric body formed on one side surface of the substrate; an electrode layer is made, the electrode layer covers the piezoelectric body and covers the remaining surface of the substrate; the electrode layer is etched to form a first electrode and a second electrode arranged along the thickness direction of the substrate and located on both sides of the piezoelectric body, the first electrode, the piezoelectric body and the second electrode constitute a piezoelectric sensing structure, and an air ring structure is made between the first electrode and the piezoelectric body, and another air ring structure is made between the second electrode and the piezoelectric body; a shell structure is made, the shell structure is covered and fixed above the substrate to form a cavity accommodating the piezoelectric sensing structure, and the two air ring structures are both connected to the cavity; an electrical connection structure is made, the electrical connection structure includes a first electrical connector and a second electrical connector, the first electrical connector is electrically connected to the first electrode, the second electrical connector is electrically connected to the second electrode, and the first electrical connector and the second electrical connector are at least partially located outside the cavity.

[0006] Furthermore, before the step of making the electrode layer, the manufacturing method also includes: making a first sacrificial layer on the piezoelectric body, and etching the first sacrificial layer so that the first sacrificial layer is located on two opposite sides of the piezoelectric body, and the first sacrificial layer partially covers the side surfaces of the piezoelectric body; during the step of making the electrode layer, the etched first sacrificial layer is located between the electrode layer and the piezoelectric body.

[0007] Further, during the step of etching the electrode layer, a portion of the first sacrificial layer after etching is located between the first electrode and the piezoelectric body, and the portion of the first sacrificial layer is not completely covered by the first electrode, and another portion of the first sacrificial layer after etching is located between the second electrode and the piezoelectric body, and the portion of the first sacrificial layer is not completely covered by the second electrode; after the step of etching the electrode layer, the first sacrificial layer is completely released to form an air ring structure between the first electrode and the piezoelectric body, and another air ring structure is formed between the second electrode and the piezoelectric body.

[0008] Furthermore, the manufacturing method of the shell structure includes: forming a second sacrificial layer on the substrate so that the second sacrificial layer covers the first electrode and the second electrode; forming a passivation layer on the substrate, and the cavity between the passivation layer and the substrate covers the piezoelectric body, the second sacrificial layer, the first electrode and the second electrode; openings are made on the passivation layer and the second sacrificial layer to expose the first electrode and the second electrode; after the electrical connection structure is manufactured, the second sacrificial layer is released to form a cavity to accommodate the piezoelectric sensing structure.

[0009] Furthermore, there is a predetermined angle between the piezoelectric body and the substrate, and the predetermined angle is 85°-90°.

[0010] Furthermore, the piezoelectric body stands on the substrate and encloses a closed regular shape or an irregular shape, or the piezoelectric body is an open shape.

[0011] Furthermore, there is at least one piezoelectric body. If there are two or more piezoelectric bodies, the distance between two adjacent piezoelectric bodies is greater than 1 μm.

[0012] Furthermore, in the step of manufacturing a first sacrificial layer on the piezoelectric body, the thickness of the manufactured first sacrificial layer is 10nm-500nm.

[0013] Further, after the step of etching the first sacrificial layer so that the first sacrificial layer is located on two opposite sides of the piezoelectric body, the first sacrificial layer is divided into two parts, one part of which is located on one side of the piezoelectric body and on the side of the piezoelectric body close to the substrate, and the other part is located on the other side of the piezoelectric body and on the side of the piezoelectric body away from the substrate, or the first sacrificial layer is divided into four parts, two of which are located on one side of the piezoelectric body and are respectively located on the two sides of the piezoelectric body close to and away from the substrate, and the other two parts are located on the other side of the piezoelectric body and are respectively located on the two sides of the piezoelectric body close to and away from the substrate.

[0014] Further, after the first sacrificial layer is divided into two parts or four parts, in the direction from the first electrode to the piezoelectric body, the width of each part of the first sacrificial layer is 0.1 μm-1 μm.

[0015] Further, the step of etching the electrode layer includes: etching the electrode layer to form an electrode on two opposite sides of the piezoelectric body having the first sacrificial layer;

[0016] Etching the electrode end portion corresponding to the first sacrificial layer close to the substrate to form a gap between the substrate and the electrode and partially expose the first sacrificial layer to form a first electrode;

[0017] The electrode end portion corresponding to the first sacrificial layer away from the substrate is etched to form a gap on the side of the electrode away from the substrate, and the first sacrificial layer is exposed to form a second electrode.

[0018] Furthermore, when etching the electrode end corresponding to the first sacrificial layer close to the substrate, the electrode end is etched away by 0.1 μm-0.5 μm to expose the first sacrificial layer; when etching the electrode end corresponding to the first sacrificial layer far from the substrate, the electrode end is etched away by 0.1 μm-0.5 μm to expose the first sacrificial layer.

[0019] Further, when making the electrical connection structure, if the first electrode and the second electrode are both completely located in the cavity, the first connector passes through the shell structure and is electrically connected to the first electrode, and the second connector passes through the shell structure and is electrically connected to the second electrode, or, when making the electrical connection structure, if the first electrode partially extends out of the cavity, the first connector is electrically connected to the first electrode outside the shell structure, or / and, if the second electrode partially extends out of the cavity, the second connector is electrically connected to the first electrode outside the shell structure.

[0020] According to the second aspect of the present invention, the present invention also provides a filter, comprising: a substrate; a piezoelectric body, which is arranged on one side of the substrate, and the piezoelectric body stands on the substrate; a first electrode and a second electrode, which are respectively arranged on both sides of the piezoelectric body, and an air ring structure is provided between part of the first electrode, part of the second electrode and the piezoelectric body, and the first electrode, the piezoelectric body and the second electrode constitute a piezoelectric sensing structure; a shell structure, which is covered and fixed above the substrate to form a cavity for accommodating the piezoelectric sensing structure, and the air ring structure is connected to the cavity; an electrical connection structure, comprising a first electrical connector and a second electrical connector, the first electrical connector is electrically connected to the first electrode, the second electrical connector is electrically connected to the second electrode, and the first electrical connector and the second electrical connector are at least partially located outside the cavity.

[0021] Furthermore, there is a predetermined angle between the piezoelectric body and the substrate, and the predetermined angle is 85°-90°.

[0022] Furthermore, the piezoelectric body is enclosed into a closed regular shape or an irregular shape, or the piezoelectric body is an open shape.

[0023] Furthermore, there is at least one piezoelectric body. If there are two or more piezoelectric bodies, the distance between two adjacent piezoelectric bodies is greater than 1 μm.

[0024] Furthermore, there are two air ring structures, one of which is located on one side of the piezoelectric body and on the side of the piezoelectric body close to the substrate, and the other air ring structure is located on the other side of the piezoelectric body and on the side of the piezoelectric body away from the substrate.

[0025] Furthermore, there are four air ring structures, two of which are located on one side of the piezoelectric body and are respectively located on both sides of the piezoelectric body close to and away from the substrate, and the other two air ring structures are located on the other side of the piezoelectric body and are respectively located on both sides of the piezoelectric body close to and away from the substrate.

[0026] Furthermore, in the direction from the first electrode to the piezoelectric body, the depth of each air ring structure is 0.1 μm-1 μm.

[0027] Furthermore, among the first electrode and the second electrode, in the direction from the substrate to the piezoelectric body, the distance between one end of one electrode close to the substrate and the substrate is 0.1μm-0.5μm, and the distance between one end of the other electrode away from the substrate and the passivation layer is 0.1μm-0.5μm.

[0028] Furthermore, the first electrode and the second electrode are all located in the cavity, the first connector passes through the shell structure and is electrically connected to the first electrode, and the second electrical connector passes through the shell structure and is electrically connected to the second electrode.

[0029] Further, the first electrode partially extends out of the cavity, and the first connector is electrically connected to the first electrode outside the shell structure, or / and the second electrode partially extends out of the cavity, and the second electrical connector is electrically connected to the first electrode outside the shell structure.

[0030] Through one or more of the above embodiments of the present invention, at least the following technical effects can be achieved:

[0031] In the technical solution disclosed in the present invention, the filter produced is a lateral sandwich structure as an overall structure. During the production process, the two electrodes are located on the same side of the substrate, so there is no need to perform photolithography on both sides. When making a cavity, a shell structure can be directly made on the substrate, and there is no need to bond another wafer to make the cavity. Therefore, the complexity of the filter processing technology can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The technical solutions and other beneficial effects of the present invention will be made apparent by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0033] Figure 1 A flowchart of a method for manufacturing a filter provided by an embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the structure of a piezoelectric layer fabricated on a substrate in a method for manufacturing a filter provided in an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of the structure after the piezoelectric layer is etched into a piezoelectric body in the method for manufacturing the filter provided in an embodiment of the present invention;

[0036] Figure 4 A structural top view of the shape and distance of the piezoelectric body of the filter manufacturing method provided by the embodiment of the present invention;

[0037] Figure 5 A schematic diagram of the structure of the filter manufacturing method provided in an embodiment of the present invention after the first sacrificial layer is manufactured;

[0038] Figure 6 A schematic structural diagram of the filter manufacturing method provided in an embodiment of the present invention after etching the first sacrificial layer;

[0039] Figure 7A schematic structural diagram of a filter manufacturing method provided by another embodiment of the present invention after etching the first sacrificial layer;

[0040] Figure 8 A schematic diagram of the structure of the filter manufacturing method provided by an embodiment of the present invention after the conductive layer is manufactured;

[0041] Fig. 9 A schematic structural diagram of a filter manufacturing method provided in an embodiment of the present invention after etching a conductive layer to generate a first electrode and a second electrode;

[0042] Fig.10 A schematic structural diagram of the filter manufacturing method provided in an embodiment of the present invention after etching the first electrode and the second electrode;

[0043] Fig.11 A schematic diagram of the structure after the second sacrificial layer is manufactured by the manufacturing method of the filter provided in an embodiment of the present invention;

[0044] Fig.12 A schematic structural diagram of the filter manufacturing method provided in an embodiment of the present invention after etching the second sacrificial layer;

[0045] Fig.13 A schematic structural diagram of a method for manufacturing a filter provided in an embodiment of the present invention after a passivation layer is disposed on a substrate;

[0046] Fig.14 A schematic structural diagram of a method for manufacturing a filter provided in an embodiment of the present invention after the passivation layer is opened to expose the first electrode and the second electrode;

[0047] Fig.15 A schematic diagram of the structure after manufacturing the first electrical connector and the second electrical connector of the filter manufacturing method provided by the embodiment of the present invention;

[0048] Fig.16 A schematic diagram of the filter structure obtained after releasing the first sacrificial layer and the second sacrificial layer in the filter manufacturing method provided by an embodiment of the present invention;

[0049] Fig.17 A schematic structural diagram of a filter manufactured by a filter manufacturing method provided by another embodiment of the present invention.

[0050] Reference numerals:

[0051] 1. Substrate; 2. Piezoelectric layer; 21. Piezoelectric body; 3. First sacrificial layer; 4. Electrode layer; 41. First electrode; 42. Second electrode; 5. Air ring structure; 6. Shell structure; 7. Electrical connection structure; 71. First electrical connection member; 72. Second electrical connection member; 8. Second sacrificial layer; 9. Passivation layer. DETAILED DESCRIPTION

[0052] The technical scheme in the embodiment of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "and / or" herein is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " herein, unless otherwise specified, generally indicates that the associated objects before and after are in an "or" relationship.

[0054] The piezoelectric layer is the key material that works by utilizing the piezoelectric effect. When an electric field is applied to the piezoelectric material, the material undergoes mechanical deformation, generating sound waves. These sound waves propagate through the piezoelectric layer, forming the basis for the operation of the filter.

[0055] Therefore, the filter can use surface acoustic wave devices to achieve filtering. The existing filters basically use a longitudinal sandwich structure, but such filters have the following defects during the manufacturing process:

[0056] 1) The upper and lower electrodes require two photolithography steps, and another wafer needs to be bonded to make the upper cavity, making the filter processing more complicated;

[0057] 2) Since it requires a wafer to be bonded to make the upper cavity, another wafer needs to be photolithographically processed, which results in more photolithographic layers for the filter, further increasing the complexity of the processing technology, and using more wafers, which increases the cost of the filter;

[0058] 3) The lateral structure is equivalent to a line distribution, and the area occupied by the lines is relatively small, which results in a larger size of the filter produced.

[0059] The embodiments of the present application provide a method for manufacturing a filter and a filter, which can solve at least one of the above-mentioned defects, as follows:

[0060] Figure 1 The method for manufacturing a filter provided by an embodiment of the present invention includes:

[0061] S101, providing a substrate, manufacturing a piezoelectric layer covering the surface of the substrate on one side surface of the substrate, and etching the piezoelectric layer to form a piezoelectric body on one side surface of the substrate;

[0062] S102, manufacturing an electrode layer, wherein the electrode layer covers the piezoelectric body and the remaining surface of the substrate;

[0063] S103, etching the electrode layer to form a first electrode and a second electrode arranged along the thickness direction of the substrate and located on both sides of the piezoelectric body;

[0064] S104, manufacturing a shell structure, wherein the shell structure is covered and fixed on the top of the substrate to form a cavity for accommodating the piezoelectric sensing structure, and the two air ring structures are both connected to the cavity;

[0065] S105, manufacturing an electrical connection structure, the electrical connection structure comprising a first electrical connection member and a second electrical connection member, the first electrical connection member is electrically connected to the first electrode, the second electrical connection member is electrically connected to the second electrode, and both the first electrical connection member and the second electrical connection member are at least partially located outside the cavity.

[0066] In step S101, the piezoelectric layer 2 is made by deposition, and the deposited material is one or a combination of at least two of polycrystalline or single crystal or polycrystalline single crystal mixed aluminum nitride, aluminum scandium nitride, quartz, etc. Figure 2 shown.

[0067] After the piezoelectric layer 2 is etched, the piezoelectric layer 2 originally laid horizontally on the substrate 1 is etched into a piezoelectric body 21 vertically standing on the substrate 1. For details, please refer to Figure 3 When etching the piezoelectric layer 2, at least one piezoelectric body 21 may be etched out. This embodiment is described by taking one piezoelectric body 21 as an example. In other embodiments, two or more piezoelectric bodies 21 may also be etched out. Figure 4 As shown, there are four piezoelectric bodies 21, wherein the shape of the piezoelectric body 21 can be a closed regular figure or an irregular figure ( Figure 4 The oval in the middle and the rectangle on the right), or an open figure ( Figure 4 It should be noted that if there are two or more piezoelectric bodies 21, the distance between two adjacent piezoelectric bodies 21 is greater than 1 μm, for example Figure 4 A, B, and C in the figure all represent the distance between two adjacent piezoelectric bodies 21 . These distances are all greater than 1 μm. Such size settings are intended to leave space for making components on the piezoelectric body 21 , such as making electrodes on the piezoelectric body 21 .

[0068] In some embodiments, there is a predetermined angle between the piezoelectric body 21 and the substrate 1, and the predetermined angle is 85°-90°. The piezoelectric body 21 arranged in this way stands vertically or nearly vertically on the substrate, which can enhance its mechanical stability and strength and avoid deformation or breakage during subsequent processing or use. In addition, in surface acoustic wave devices, vertical side walls can ensure that the path and mode of sound wave propagation are consistent. Specifically: vertical side walls help reduce the reflection and diffraction of sound waves during propagation. Inclined or irregular side walls may cause scattering of sound waves and deviation of the path, thereby affecting the performance and efficiency of the device. Therefore, the piezoelectric body 21 arranged in this way in the present application can improve the performance and efficiency of the filter.

[0069] In step S102 , the electrode layer 4 is also obtained by deposition. After deposition, the electrode layer 4 can cover the piezoelectric body 21 and the remaining surface of the substrate 1 . The material of the electrode layer 4 can be molybdenum or tungsten or a mixture of the two.

[0070] In step S103, the electrode layer 4 is etched to form a first electrode 41 and a second electrode 42 electrically connected to the piezoelectric body 21 on the piezoelectric body 21, wherein the first electrode 41, the piezoelectric body 21 and the second electrode 42 constitute a piezoelectric sensing structure, and an air ring structure 5 is made between the first electrode 41 and the piezoelectric body 21, and another air ring structure 5 is made between the second electrode 42 and the piezoelectric body 21.

[0071] In this embodiment, in order to manufacture the air ring structure 5, before the step of manufacturing the electrode layer 4, it is necessary to manufacture the first sacrificial layer 3 on the electrode layer 4 and the piezoelectric body 21, such as Figure 5 As shown, the specific steps include: forming a first sacrificial layer 3 on the piezoelectric body 21, and etching the first sacrificial layer 3 so that the first sacrificial layer 3 is located on two opposite sides of the piezoelectric body 21, and the first sacrificial layer 3 partially covers the side of the piezoelectric body 21; the first sacrificial layer 3 after etching is as shown in FIG. Figure 6 or Figure 7 As shown, in this embodiment, after the step of etching the first sacrificial layer 3 so that the first sacrificial layer 3 is located on two opposite sides of the piezoelectric body 21, the first sacrificial layer 3 is divided into two parts, one of which is located on one side of the piezoelectric body 21 and is located on the side of the piezoelectric body 21 close to the substrate 1, and the other part is located on the other side of the piezoelectric body 21 and is located on the side of the piezoelectric body 21 away from the substrate 1. For details, please refer to Figure 6In other embodiments, the first sacrificial layer 3 is divided into four parts, two of which are located on one side of the piezoelectric body 21 and are located on two sides of the piezoelectric body 21 close to and away from the substrate 1, respectively, and the other two parts are located on the other side of the piezoelectric body 21 and are located on two sides of the piezoelectric body 21 close to and away from the substrate 1, respectively. Figure 7 After the first sacrificial layer 3 is divided into two parts or four parts, in the direction from the first electrode 41 to the piezoelectric body 21 , the width of each part of the first sacrificial layer 3 is 0.1 μm-1 μm.

[0072] The electrode layer 4 is manufactured after the first sacrificial layer 3 is etched. In the step of manufacturing the electrode layer 4, the etched first sacrificial layer 3 is located between the electrode layer 4 and the piezoelectric body 21. For details, please refer to Figure 8 .

[0073] In addition, during the step of etching the electrode layer 4, a portion of the first sacrificial layer 3 after etching is located between the first electrode 41 and the piezoelectric body 21, and the portion of the first sacrificial layer 3 is not completely covered by the first electrode 41, and another portion of the first sacrificial layer 3 after etching is located between the second electrode 42 and the piezoelectric body 21, and the portion of the first sacrificial layer 3 is not completely covered by the second electrode 42. For details, please refer to Fig. 9 and Fig.10 .

[0074] After the step of etching the electrode layer 4 , the first sacrificial layer 3 is completely released to form an air ring structure 5 between the first electrode 41 and the piezoelectric body 21 , and another air ring structure 5 between the second electrode 42 and the piezoelectric body 21 .

[0075] In this embodiment, by etching the air ring structure 5 , the energy leakage of the manufactured filter can be reduced and the performance of the filter can be improved.

[0076] In step S104, by manufacturing the shell structure 6 on the substrate and forming a cavity between the combined structure and the substrate, there is no need to bond a wafer to form the cavity as in the prior art.

[0077] The filter manufacturing method provided in this embodiment can be used to manufacture a bulk acoustic wave filter, or a surface acoustic wave filter, or a surface acoustic wave filter manufactured using the method for manufacturing a bulk acoustic wave filter.

[0078] Therefore, the filter manufacturing method provided in the embodiment of the present application is a filter that has an overall structure that is a lateral sandwich structure. During the manufacturing process, the two electrodes are located on the same side of the substrate, so there is no need to perform photolithography on both sides. When making a cavity, a shell structure 6 can be directly made on the substrate 1, and there is no need to bond another wafer to make the cavity. Therefore, the complexity of the filter processing technology can be reduced.

[0079] In addition, since there is no need to bond a wafer to make a cavity, there is no need to perform photolithography on the wafer, which can reduce the number of photolithography times for the filter, thereby reducing the complexity of the filter processing technology, and using fewer wafers, reducing the manufacturing cost of the filter.

[0080] In addition, the filter produced by the present application has two electrodes on the left and right sides of the piezoelectric layer 2, so that the overall structure of the filter is a horizontal sandwich structure, and the piezoelectric body 21 occupies a relatively small area of ​​the substrate, so that the filter area produced by the embodiment of the present application is smaller.

[0081] In some embodiments, see Figures 11 to 15 The manufacturing steps of the shell structure 6 include: making a second sacrificial layer 8 on the substrate 1, so that the second sacrificial layer 8 covers the first electrode 41 and the second electrode 42 (see Fig.11 and Fig.12 ); a passivation layer 9 is formed on the substrate 1 (see Fig.13 ), the cavity between the passivation layer 9 and the substrate 1 covers the piezoelectric body 21, the second sacrificial layer 8, the first electrode 41 and the second electrode 42; the passivation layer 9 and the second sacrificial layer 8 are opened (see Fig.14 ) so that the first electrode 41 and the second electrode 42 are exposed; after the electrical connection structure 7 is manufactured (see Fig.15 ), the second sacrificial layer 8 is released to form a cavity to accommodate the piezoelectric sensing structure.

[0082] In this embodiment, the shell structure 6 is manufactured so that a cavity is formed between the shell structure 6 and the substrate to accommodate the piezoelectric sensing structure, thereby eliminating the need to bond a wafer to form the cavity.

[0083] In some embodiments, the first sacrificial layer 3 after etching is released after the electrical connection structure 7 is produced, so that the second sacrificial layer 8 and the first sacrificial layer 3 after etching can be released at the same time, thereby reducing the manufacturing steps of the filter and reducing the manufacturing complexity of the filter.

[0084] In some embodiments, after the first sacrificial layer 3 is deposited, that is, before the first sacrificial layer 3 is etched, the thickness of the first sacrificial layer 3 is 10nm-500nm, wherein the material of the first sacrificial layer 3 can be one of undoped silicate glass materials, phosphosilicate glass, silicon nitride and other materials, or a mixed material of at least two of them.

[0085] In some embodiments, the step of etching the electrode layer 4 includes:

[0086] The electrode layer 4 is etched to form an electrode on two opposite sides of the piezoelectric body 21 having the first sacrificial layer 3;

[0087] The electrode end portion corresponding to the first sacrificial layer 3 close to the substrate 1 is etched to form a gap between the substrate 1 and the electrode, and the first sacrificial layer 3 is partially exposed to form a first electrode 41 (for details, please refer to Fig.10 );

[0088] The electrode end portion corresponding to the first sacrificial layer 3 away from the substrate 1 is etched to form a gap on the side of the electrode away from the substrate 1 and expose the first sacrificial layer 3 to form a second electrode 42 (for details, please refer to Fig.10 ).

[0089] The first electrode 41 and the second electrode 42 expose the etched first sacrificial layer 3 so as to form an air ring structure 5 communicating with the cavity.

[0090] In some embodiments, when etching the electrode end corresponding to the first sacrificial layer 3 close to the substrate 1, the electrode end is etched away by 0.1 μm-0.5 μm to expose the first sacrificial layer 3; when etching the electrode end corresponding to the first sacrificial layer 3 far from the substrate 1, the electrode end is etched away by 0.1 μm-0.5 μm to expose the first sacrificial layer 3.

[0091] In this embodiment, by etching, the two electrodes do not completely cover the air ring and the piezoelectric body 21, which can reduce energy loss, and the working areas of the two electrodes are spaced apart from the top and the bottom, which can reduce energy loss.

[0092] In some embodiments, see Fig.16 , when making the electrical connection structure 7, the first electrode 41 and the second electrode 42 are all located in the cavity, the first connector passes through the shell structure 6 and is electrically connected to the first electrode 41, and the second electrical connector 72 passes through the shell structure 6 and is electrically connected to the second electrode 42, or,

[0093] In other embodiments, see Fig.17, when making the electrical connection structure 7, the first electrode 41 partially extends out of the cavity, and the first connector is electrically connected to the first electrode 41 outside the shell structure 6, or / and, in other embodiments, the second electrode 42 partially extends out of the cavity, and the second electrical connector 72 is electrically connected to the first electrode 41 outside the shell structure 6. The first electrode 41 or the second electrode 42 completely outside the cavity is arranged in this way, which reduces the top opening of the shell structure 6, can make the shell structure 6 more stable, and thus improve the stability of the filter.

[0094] See also Fig.16 The embodiment of the present application also provides a filter, including: a substrate 1, a piezoelectric body 21, a first electrode 41, a second electrode 42, a shell structure 6 and an electrical connection structure 7; the piezoelectric body 21 is arranged on one side of the substrate 1, and the piezoelectric body 21 stands on the substrate 1; the first electrode 41 and the second electrode 42 are respectively arranged on both sides of the piezoelectric body 21, and an air ring structure 5 is provided between part of the first electrode 41, part of the second electrode 42 and the piezoelectric body 21, and the first electrode 41, the piezoelectric body 21 and the second electrode 42 constitute a piezoelectric sensing structure; the shell structure 6 is covered and fixed on the top of the substrate 1 to form a cavity for accommodating the piezoelectric sensing structure, and the air ring structure 5 is connected to the cavity; the electrical connection structure 7 includes a first electrical connector 71 and a second electrical connector 72, the first electrical connector 71 is electrically connected to the first electrode 41, the second electrical connector 72 is electrically connected to the second electrode 42, and the first electrical connector 71 and the second electrical connector 72 are at least partially located outside the cavity.

[0095] The filter provided in this embodiment may be a bulk acoustic wave filter, or a surface acoustic wave filter, or a surface acoustic wave filter manufactured using a manufacturing method of a bulk acoustic wave filter.

[0096] The filter provided in this embodiment has an overall structure of a lateral sandwich structure. During the manufacturing process, the two electrodes are located on the same side of the substrate, so there is no need to perform photolithography on both sides. When making a cavity, a shell structure 6 can be directly made on the substrate 1, and there is no need to bond another wafer to make the cavity. Therefore, the complexity of the filter processing technology can be reduced.

[0097] In some embodiments, there is a predetermined angle between the piezoelectric body 21 and the substrate 1 , and the predetermined angle is 85°-90°.

[0098] In some embodiments, the piezoelectric body 21 is enclosed into a closed regular shape or an irregular shape, or the piezoelectric body 21 is an open shape.

[0099] In some embodiments, there is at least one piezoelectric body 21 . If there are two or more piezoelectric bodies 21 , the distance between two adjacent piezoelectric bodies 21 is greater than 1 μm.

[0100] In some embodiments, there are two air ring structures 5, one of which is located on one side of the piezoelectric body 21 and on the side of the piezoelectric body 21 close to the substrate 1, and the other air ring structure 5 is located on the other side of the piezoelectric body 21 and on the side of the piezoelectric body 21 away from the substrate 1.

[0101] In some embodiments, there are four air ring structures 5, two of which are located on one side of the piezoelectric body 21, and are respectively located on both sides of the piezoelectric body 21 close to and away from the substrate 1, and the other two air ring structures 5 are located on the other side of the piezoelectric body 21, and are respectively located on both sides of the piezoelectric body 21 close to and away from the substrate 1.

[0102] In some embodiments, in the direction from the first electrode 41 to the piezoelectric body 21 , the depth of each air ring structure 5 is 0.1 μm-1 μm.

[0103] In some embodiments, among the first electrode 41 and the second electrode 42, and in the direction from the substrate 1 to the piezoelectric body 21, the distance between one end of one electrode close to the substrate 1 and the substrate 1 is 0.1μm-0.5μm, and the distance between one end of the other electrode away from the substrate 1 and the passivation layer 9 is 0.1μm-0.5μm.

[0104] In some embodiments, the first electrode 41 and the second electrode 42 are all located in the cavity, the first connector passes through the shell structure 6 and is electrically connected to the first electrode 41, and the second electrical connector 72 passes through the shell structure 6 and is electrically connected to the second electrode 42. In some embodiments, the first electrode 41 partially extends out of the cavity, the first connector is electrically connected to the first electrode 41 outside the shell structure 6, or / and the second electrode 42 partially extends out of the cavity, and the second electrical connector 72 is electrically connected to the first electrode 41 outside the shell structure 6.

[0105] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for manufacturing a filter, characterized in that: include: Providing a substrate, manufacturing a piezoelectric layer covering the surface of the substrate on one side surface of the substrate, and etching the piezoelectric layer to form a piezoelectric body on the one side surface of the substrate; Manufacturing an electrode layer, wherein the electrode layer covers the piezoelectric body and the remaining surface of the substrate; Etching the electrode layer to form a first electrode and a second electrode arranged along the thickness direction of the substrate and located on both sides of the piezoelectric body, wherein the first electrode, the piezoelectric body and the second electrode constitute a piezoelectric sensing structure, and an air ring structure is made between the first electrode and the piezoelectric body, and another air ring structure is made between the second electrode and the piezoelectric body; Making a shell structure, wherein the shell structure is covered and fixed on the top of the base to form a cavity for accommodating the piezoelectric sensing structure, and the two air ring structures are both connected to the cavity; An electrical connection structure is manufactured, wherein the electrical connection structure includes a first electrical connection member and a second electrical connection member, wherein the first electrical connection member is electrically connected to the first electrode, the second electrical connection member is electrically connected to the second electrode, and the first electrical connection member and the second electrical connection member are at least partially located outside the cavity.

2. The method for manufacturing a filter according to claim 1, wherein: Before the step of manufacturing the electrode layer, the manufacturing method further comprises: Making a first sacrificial layer on the piezoelectric body, and etching the first sacrificial layer so that the first sacrificial layer is located on two opposite sides of the piezoelectric body, and the first sacrificial layer partially covers the side of the piezoelectric body; In the step of manufacturing the electrode layer, the etched first sacrificial layer is located between the electrode layer and the piezoelectric body.

3. The method for manufacturing a filter according to claim 2, wherein: In the step of etching the electrode layer, a portion of the first sacrificial layer after etching is located between the first electrode and the piezoelectric body, and the portion of the first sacrificial layer is not completely covered by the first electrode, and another portion of the first sacrificial layer after etching is located between the second electrode and the piezoelectric body, and the portion of the first sacrificial layer is not completely covered by the second electrode; After the step of etching the electrode layer, the first sacrificial layer is completely released to form an air ring structure between the first electrode and the piezoelectric body, and another air ring structure between the second electrode and the piezoelectric body.

4. The method for manufacturing a filter according to claim 1, wherein: The manufacturing steps of the shell structure include: forming a second sacrificial layer on the substrate so that the second sacrificial layer covers the first electrode and the second electrode; A passivation layer is formed on the substrate, wherein the cavity between the passivation layer and the substrate covers the piezoelectric body, the second sacrificial layer, the first electrode and the second electrode; opening the passivation layer and the second sacrificial layer to expose the first electrode and the second electrode; After the electrical connection structure is manufactured, the second sacrificial layer is released to form a cavity for accommodating the piezoelectric sensing structure.

5. The method for manufacturing a filter according to claim 1, wherein: There is a predetermined angle between the piezoelectric body and the substrate, and the predetermined angle is 85°-90°.

6. The method for manufacturing a filter according to claim 1, wherein: The piezoelectric body is enclosed into a closed regular shape or an irregular shape, or the piezoelectric body is an open shape.

7. The method for manufacturing a filter according to claim 1, wherein: There is at least one piezoelectric body. If there are two or more piezoelectric bodies, the distance between two adjacent piezoelectric bodies is greater than 1 μm.

8. The method for manufacturing a filter according to claim 2, wherein: In the step of manufacturing a first sacrificial layer on the piezoelectric body, the thickness of the manufactured first sacrificial layer is 10nm-500nm.

9. The method for manufacturing a filter according to claim 2, wherein: After the step of etching the first sacrificial layer so that the first sacrificial layer is located on two opposite sides of the piezoelectric body, the first sacrificial layer is divided into two parts, one of which is located on one side of the piezoelectric body and on the side of the piezoelectric body close to the substrate, and the other is located on the other side of the piezoelectric body and on the side of the piezoelectric body away from the substrate, or, The first sacrificial layer is divided into four parts, two of which are located on one side of the piezoelectric body and are respectively located on both sides of the piezoelectric body close to and far from the substrate, and the other two parts are located on the other side of the piezoelectric body and are respectively located on both sides of the piezoelectric body close to and far from the substrate.

10. The method for manufacturing a filter according to claim 9, wherein: After the first sacrificial layer is divided into two parts or four parts, in the direction from the first electrode to the piezoelectric body, the width of each part of the first sacrificial layer is 0.1 μm-1 μm.

11. The method for manufacturing a filter according to claim 9, wherein: The step of etching the electrode layer comprises: Etching the electrode layer to form an electrode on opposite sides of the piezoelectric body having the first sacrificial layer; Etching the electrode end portion corresponding to the first sacrificial layer close to the substrate to form a gap between the substrate and the electrode and partially expose the first sacrificial layer to form a first electrode; The electrode end portion corresponding to the first sacrificial layer away from the substrate is etched to form a gap on the side of the electrode away from the substrate, and the first sacrificial layer is exposed to form a second electrode.

12. The method for manufacturing a filter according to claim 11, wherein: When etching the electrode end portion corresponding to the first sacrificial layer close to the substrate, the electrode end portion is etched away by 0.1 μm-0.5 μm to expose the first sacrificial layer; The electrode end portion corresponding to the first sacrificial layer far away from the substrate is etched, and the electrode end portion is etched away by 0.1 μm-0.5 μm to expose the first sacrificial layer.

13. The method for manufacturing a filter according to claim 1, wherein: When making the electrical connection structure, if the first electrode and the second electrode are both completely located in the cavity, the first electrical connection member penetrates the shell structure and is electrically connected to the first electrode, and the second electrical connection member penetrates the shell structure and is electrically connected to the second electrode, or, When manufacturing the electrical connection structure, if the first electrode partially extends out of the cavity, the first electrical connector is electrically connected to the first electrode outside the shell structure, or / and if the second electrode partially extends out of the cavity, the second electrical connector is electrically connected to the first electrode outside the shell structure.

14. A filter, characterized in that: include: substrate; A piezoelectric body is disposed on one side of the substrate, and the piezoelectric body stands on the substrate; A first electrode and a second electrode are respectively arranged on both sides of the piezoelectric body, and an air ring structure is provided between a part of the first electrode, a part of the second electrode and the piezoelectric body, and the first electrode, the piezoelectric body and the second electrode constitute a piezoelectric sensing structure; A shell structure, which is covered and fixed on the base to form a cavity for accommodating the piezoelectric sensing structure, and the air ring structure is connected to the cavity; The electrical connection structure includes a first electrical connection member and a second electrical connection member, wherein the first electrical connection member is electrically connected to the first electrode, the second electrical connection member is electrically connected to the second electrode, and both the first electrical connection member and the second electrical connection member are at least partially located outside the cavity.

15. The filter according to claim 14, characterized in that There is a predetermined angle between the piezoelectric body and the substrate, and the predetermined angle is 85°-90°.

16. The filter according to claim 14, characterized in that The piezoelectric body is enclosed into a closed regular shape or an irregular shape, or the piezoelectric body is an open shape.

17. The filter according to claim 14, characterized in that There is at least one piezoelectric body. If there are two or more piezoelectric bodies, the distance between two adjacent piezoelectric bodies is greater than 1 μm.

18. The filter according to claim 14, characterized in that There are two air ring structures, one of which is located on one side of the piezoelectric body and on the side of the piezoelectric body close to the substrate, and the other air ring structure is located on the other side of the piezoelectric body and on the side of the piezoelectric body away from the substrate.

19. The filter according to claim 14, characterized in that There are four air ring structures, two of which are located on one side of the piezoelectric body and are respectively located on both sides of the piezoelectric body close to and far away from the substrate, and the other two air ring structures are located on the other side of the piezoelectric body and are respectively located on both sides of the piezoelectric body close to and far away from the substrate.

20. The filter according to claim 18 or 19, characterized in that In a direction from the first electrode to the piezoelectric body, a depth of each air ring structure is 0.1 μm-1 μm.

21. The filter according to claim 14, characterized in that Among the first electrode and the second electrode, in the direction from the substrate to the piezoelectric body, the distance between one end of one electrode close to the substrate and the substrate is 0.1μm-0.5μm, and the distance between the other end of the electrode away from the substrate and the passivation layer is 0.1μm-0.5μm.

22. The filter according to claim 14, characterized in that The first electrode and the second electrode are all located in the cavity, the first electrical connector passes through the shell structure and is electrically connected to the first electrode, and the second electrical connector passes through the shell structure and is electrically connected to the second electrode.

23. The filter according to claim 14, characterized in that The first electrode partially extends out of the cavity, and the first electrical connector is electrically connected to the first electrode outside the shell structure, or / and the second electrode partially extends out of the cavity, and the second electrical connector is electrically connected to the first electrode outside the shell structure.

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