Packaging method of film bulk acoustic resonator and film bulk acoustic resonator

Abstract

The invention provides a packaging method of a film bulk acoustic resonator and the film bulk acoustic resonator, and the packaging method comprises the steps: providing a resonant cavity main body structure which comprises a substrate and a piezoelectric laminated structure formed on the substrate, and forming a first cavity between the substrate and the piezoelectric laminated structure; arranging a bonding layer outside the first cavity area on one side, far away from the substrate, of the piezoelectric laminated structure; and etching the piezoelectric laminated structure to form a release hole communicated with the first cavity. The bonding layer is firstly arranged, and then the release hole communicated with the first cavity is formed through etching, so that heat generated in the curing stage of the bonding layer cannot enter the first cavity through the release hole, the situation that gas in the first cavity is heated to expand is effectively avoided, and the problem that glue bubbles are formed in or on the surface of the bonding layer is solved; and the stability of the packaging process is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a packaging method of film bulk acoustic resonator and film bulk acoustic resonator. BACKGROUND

[0002] Film bulk acoustic resonator (FBAR) includes electrodes typically disposed on and / or under a piezoelectric layer and a corresponding cavity. In response to a high frequency signal applied to the electrodes, the piezoelectric layer can oscillate. FBAR can be used in a wireless signal transmission system to achieve input and / or output of wireless data. For example, FBAR can be used in a wireless communication device, a wireless power transmitter, a filter of a wireless sensor, a transmitter, a receiver, a duplexer, etc.

[0003] In the process of preparing the film bulk acoustic resonator, in order to balance the air pressure, it is usually necessary to set a release hole in the piezoelectric layer structure. Due to the existence of the release hole, during the process of making the bonding layer in the process of acoustic encapsulation of the film, the bonding layer will produce glue bubbles inside or on the surface, and these glue bubbles will have a risk of breaking during the implementation of the subsequent process, thereby causing damage to the structure of the film bulk acoustic resonator. SUMMARY

[0004] The problem solved by the present application is the problem of glue bubbles during the process of making the bonding layer in the process of making the film bulk acoustic resonator.

[0005] To solve the above problems, the present application provides a packaging method of film bulk acoustic resonator, which comprises: providing a resonant cavity main structure, which comprises a substrate and a piezoelectric layer structure formed on the substrate, and a closed first cavity is formed between the substrate and the piezoelectric layer structure; setting a bonding layer on the side of the piezoelectric layer structure away from the substrate outside the first cavity area, and then etching the piezoelectric layer structure to form a release hole communicating with the first cavity.

[0006] Optionally, the piezoelectric layer structure comprises a first electrode, a piezoelectric layer and a second electrode disposed in sequence on the substrate, and before the bonding layer is set outside the first cavity area, it further comprises: setting a conductive connection layer on the piezoelectric layer structure outside the first cavity, and the bonding layer covers at least part of the conductive connection layer.

[0007] Technical effect: by setting the bonding layer on the piezoelectric layer structure outside the first cavity, the subsequent bonding with the cover can be realized through the bonding layer, and the conductive connection layer and the piezoelectric layer structure can also be protected.

[0008] Optionally, the material of the bonding layer is an organic photosensitive material.

[0009] Optionally, the step of providing a bonding layer on the side of the piezoelectric stack structure away from the substrate outside the first cavity region comprises, applying an organic photosensitive material to the side of the piezoelectric stack structure away from the substrate, and after curing the organic photosensitive material, removing at least the organic photosensitive material above the first cavity region to form the bonding layer.

[0010] Optionally, the packaging method further comprises: providing a cover, and bonding the cover with the bonding layer to form a second cavity, the second cavity being in communication with the first cavity through the release hole.

[0011] Technical effects: After the bonding layer is provided on the conductive connection layer, the bonding layer can withstand the extrusion force of the roller during the packaging process of the film, effectively avoiding the risk of cracking of the conductive connection layer or other bonding materials due to direct pressure. This design allows the cover to be directly packaged with the bonding layer, eliminating the need for additional buffer or protection structures such as the substrate preparation step in traditional processes. This not only simplifies the process and reduces manufacturing costs, but also reduces the thickness of the intermediate layer, ultimately achieving a reduction in the overall thickness of the packaged device.

[0012] Optionally, the packaging method further comprises: forming a through hole through the cover and the bonding layer, the through hole exposing the conductive connection layer; forming a conductive interconnection layer on the surface of the through hole, the conductive interconnection layer being connected with the conductive connection layer.

[0013] Technical effects: By providing a through hole on the bonding layer and the cover, and providing a conductive interconnection layer in the through hole, the first electrode and the second electrode in the piezoelectric stack structure can be connected to the external circuit through the conductive interconnection layer and the conductive connection layer.

[0014] Optionally, the material of the cover is an organic photosensitive material.

[0015] Optionally, the etching the piezoelectric stack structure to form a release hole communicating with the first cavity comprises: providing a patterned first mask on the side of the bonding layer and the piezoelectric stack structure away from the substrate; etching the piezoelectric stack structure in the first cavity according to the first mask to form a release hole communicating with the first cavity; removing the first mask.

[0016] Optionally, the providing a resonant cavity main structure comprises: providing a carrier substrate and forming the piezoelectric stack structure and a support layer on the carrier substrate; etching the support layer to form the first cavity in the support layer; providing the substrate and bonding the substrate to a side of the support layer away from the piezoelectric stack structure; removing the carrier substrate to form the resonant cavity body structure.

[0017] The embodiments of the present application also provide a thin film bulk acoustic resonator, which is obtained by the packaging method of the thin film bulk acoustic resonator according to any one of the above, comprising: a resonant cavity body structure, which comprises a substrate and a piezoelectric stack structure arranged on the substrate, and a first cavity is formed between the substrate and the piezoelectric stack structure; a bonding layer, which is arranged on a side of the piezoelectric stack structure away from the substrate and is located outside the first cavity area; a release hole, which passes through the piezoelectric stack structure to communicate with the first cavity.

[0018] Compared with the prior art, the technical scheme of the present application has the following beneficial effects: 1. The packaging method of the thin film bulk acoustic resonator provided by the embodiments of the present application, by arranging the bonding layer first and then etching to form the release hole communicating with the first cavity, the heat generated during the curing stage of the bonding layer cannot enter the inside of the first cavity through the release hole, thereby effectively avoiding the situation that the gas in the first cavity expands due to heat, so as to solve the problem of the formation of glue bubbles in the inside or surface of the bonding layer, thereby improving the stability of the packaging process, and also avoiding the flow of liquid bonding material into the first cavity to cause the functional failure of the device.

[0019] 2. The packaging method of the present application, by arranging the bonding layer first and then arranging the release hole, the bonding material does not need to consider whether heat is generated during the curing process after being coated during the selection process, and can be adapted for use.

[0020] 3. The packaging method of the present application, by arranging the bonding layer on one side of the conductive connection layer, the packaging of the cover body can be realized, and the protection of the conductive connection layer and the piezoelectric stack structure can also be realized.

[0021] 4. The encapsulation method of this application, by setting a bonding layer on the periphery of at least part of the conductive connection layer and / or piezoelectric stack structure, can effectively prevent chemical reagents such as etching solution and cleaning solution in subsequent processes from penetrating into the conductive connection layer and piezoelectric stack, avoiding corrosion of conductive lines and damage to the performance of piezoelectric materials; at the same time, it can also serve as a "structural support frame", enhancing the overall stability of the conductive connection layer and piezoelectric stack, avoiding problems such as film peeling and cracking caused by overload operation of thin film bulk acoustic resonators in abnormal environments, and improving the structure's impact resistance and fatigue resistance.

[0022] 5. In the encapsulation method of this application, after a bonding layer is provided on the conductive connection layer, the bonding layer can withstand the squeezing force of the rollers during the encapsulation film application process, effectively avoiding the risk of cracking of the conductive connection layer or other bonding materials due to direct pressure. This design allows the cover to be encapsulated with the bonding layer using thin-film acoustic device encapsulation technology, eliminating the need for additional buffer or protective structure (e.g., substrate) preparation steps in traditional processes. This not only simplifies the process and reduces manufacturing costs, but also reduces the overall thickness of the encapsulated device by reducing the thickness of the intermediate layer, without affecting the performance of the first and second cavities. Attached Figure Description

[0023] Figure 1 A schematic flowchart illustrating the packaging method for a thin-film bulk acoustic resonator provided in an embodiment of this application; Figure 2 This is a schematic diagram of the process flow corresponding to the packaging method provided in the embodiments of this application; Figure 3 for Figure 1 The packaging method shown provides a flowchart illustrating the main structure of the resonant cavity. Figure 4 for Figure 3 A schematic diagram of the process flow corresponding to the packaging method shown; Figure 5 for Figure 1 The diagram shows a process for setting a release hole in the encapsulation method. Figure 6 for Figure 1 The diagram shows a process flow diagram for setting up a conductive interconnect layer in the encapsulation method.

[0024] Explanation of reference numerals in the attached figures: 1. Thin-film bulk acoustic resonator; 11. Substrate; 12. Piezoelectric stack structure; 13. Support layer; 14. Bonding layer; 15. First cavity; 16. Release hole; 17. Conductive interconnect layer; 18. Carrier substrate; 19. First mask; 20. Cover; 21. Through-hole; 22. Conductive interconnect layer; 23. Second mask; 24. Seed layer; 25. Second cavity; 101, first electrode; 102, piezoelectric layer; 103, second electrode; 104, second electrode material layer; 105, piezoelectric material layer; 106, first electrode material layer; 107, support layer material layer. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below.

[0026] Please refer to Figure 1 and Figure 2 , Figure 1 The flowchart of the packaging method of the film bulk acoustic resonator provided by the embodiment of the present application is shown in Figure 2 The process flowchart corresponding to the packaging method provided by the embodiment of the present application is shown in the embodiment of the present application, and the packaging method of the film bulk acoustic resonator 1 includes the following flow: 110, providing a resonant cavity main structure, the resonant cavity main structure includes a substrate and a piezoelectric layer structure formed on the substrate, and a closed first cavity is formed between the substrate and the piezoelectric layer structure.

[0027] The piezoelectric layer structure 12 includes a first electrode 101, a piezoelectric layer 102 and a second electrode 103 arranged in sequence on the substrate 11, in some embodiments, the flow of providing the resonant cavity main structure is shown in Figure 3 and Figure 4 , Figure 3 The flowchart of the packaging method shown in Figure 1 is shown in Figure 4 The process flowchart corresponding to the packaging method shown in Figure 3 is shown in detail as follows: 111, providing a carrier substrate, and forming a piezoelectric layer structure and a support layer on the carrier substrate.

[0028] For example, a second electrode material layer 104 for making a second electrode 103, a piezoelectric material layer 105 for making a piezoelectric layer 102, and a first electrode material layer 106 for making a first electrode 101 are sequentially covered on the surface of the carrier substrate 18 by evaporation, magnetron sputtering and other methods to form a film layer for making a bulk acoustic resonant structure; then the first electrode material layer 106 is etched to form the first electrode 101 by exposure, development and etching process; then the support layer material layer 107 for making the support layer 13 is covered on the surface of the first electrode 101 and the piezoelectric layer 102 by evaporation, magnetron sputtering and other methods.

[0029] The carrier substrate 18 can be any one of a bare silicon wafer, a ceramic substrate, a quartz or a glass substrate. The material of the first electrode material layer 106 and the second electrode material layer 104 includes, but is not limited to, at least one metal of Ag, Au, Cu, Pd, Cr, Mo, Ti, Ta, Sn, W and Al. The material of the piezoelectric layer 102 can use a piezoelectric material with a wurtzite crystal structure, such as ZnO, AlN, GaN, lead zirconate titanate, lead titanate, etc. The material of the support layer 13 is, for example, one or a combination of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3) and aluminum nitride.

[0030] 112. Etching the support layer to form a first cavity in the support layer.

[0031] The support layer material layer 107 is etched to form the support layer 13 for supporting the piezoelectric layer structure 12, and the support layer 13, the first electrode 101 and the subsequently provided substrate 11 surround to form the first cavity 15.

[0032] 113. Providing a substrate and bonding the substrate to the side of the support layer away from the piezoelectric layer structure.

[0033] The bonding of the substrate 11 to the support layer 13 can be achieved by means of thermal compression bonding. After the bonding process is completed, the bonded film bulk acoustic resonator 1 is turned over for subsequent steps.

[0034] The substrate 11 can be bonded to the support layer 13 by any suitable bonding process known to those skilled in the art, for example, the substrate 11 can be bonded to the support layer 13 by applying hot melt glue or the like on the substrate 11. In this way, the first cavity 15 is enclosed between the substrate 11 and the first electrode 101. For example, the substrate 11 is bonded to the support layer 13 by vacuum bonding, and the conditions of the vacuum bonding process can include a bonding pressure of 1 Pa to 105 Pa and a bonding temperature of 150°C to 200°C.

[0035] 114. Removing the carrier substrate to form a resonant cavity main structure.

[0036] For example, the back of the carrier substrate 18 is thinned, which can be thinned by a chemical mechanical polishing process, and then the remaining carrier substrate 18 is removed by a wet etching process to expose the second electrode 103.

[0037] After the carrier substrate 18 is removed, the second electrode material layer 104 is etched to form the second electrode 103 by exposure, development and etching processes.

[0038] In some embodiments, to facilitate the removal of the carrier substrate 18, an isolation layer can also be formed on the carrier substrate 18 between the carrier substrate 18 and the subsequently formed first electrode 101. In a subsequent peeling process, the carrier substrate 18 can be separated from the formed first electrode 101 by etching the isolation layer, which helps to peel off the carrier substrate 18 and improves the process production efficiency. If no isolation layer is formed between the carrier substrate 18 and the first electrode 101, the carrier substrate 18 can be removed by mechanical grinding or other methods. The material of the isolation layer includes, but is not limited to, at least one of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and aluminum nitride (AlN). The isolation layer can be formed by chemical vapor deposition, magnetron sputtering, or evaporation, etc.

[0039] 120. A bonding layer is disposed on the side of the piezoelectric stack structure away from the substrate outside the first cavity region, and then the piezoelectric stack structure is etched to form a release hole communicating with the first cavity.

[0040] It should be noted that before the bonding layer 14 is disposed outside the first cavity 15 region, it also includes: disposing a conductive connection layer 17 on the piezoelectric stack structure 12 outside the first cavity 15, and the bonding layer 14 covers at least part of the conductive connection layer 17.

[0041] The conductive connection layer 17 is disposed on both sides of the piezoelectric stack structure 12 outside the first cavity 15, wherein the step of disposing the conductive connection layer 17 can be: disposing a seed layer 24 on the side of the piezoelectric stack structure 12 away from the substrate 11, disposing a second mask 23 with a pattern on the seed layer 24 to define a conductive area for forming the conductive connection layer 17; disposing a conductive material for forming the conductive connection layer 17 on the side of the piezoelectric stack structure 12 away from the substrate 11; removing the second mask 23 to form the conductive material of the conductive area into the conductive connection layer 17; and removing the seed layer 24 outside the conductive connection layer 17 by etching.

[0042] The conductive material for forming the conductive connection layer 17 can be disposed on the side of the piezoelectric stack structure 12 away from the substrate 11 by electroplating, wherein the conductive material can be metal ions such as copper, titanium, silver, etc., which are not specifically limited here.

[0043] In some embodiments, the seed layer 24 can be formed by PVD process deposition of 500A Ti+3000A Cu. By disposing the seed layer 24, intermetallic diffusion can be inhibited, for example, to prevent the conductive material from diffusing to the piezoelectric layer 102 at high temperature and causing degradation of the piezoelectric performance of the piezoelectric layer 102.

[0044] The bonding layer 14 is disposed on the side of the conductive connection layer 17 away from the substrate 11, so as to facilitate the subsequent bonding with the cover 20 through the bonding layer 14.

[0045] It should be noted that the bonding layer 14 can completely cover the side of the conductive connection layer 17 away from the substrate 11, or can cover part of the side of the conductive connection layer 17 away from the substrate 11. The specific selection can be made according to the actual situation. For example, the bonding layer 14 completely covering the conductive connection layer 17 can ensure that the entire conductive area is protected from the external environment. If the conductive connection layer 17 has a reserved test point, an electrode lead-out end, or an electrical connection window with other structures, the bonding layer 14 can be partially covered to avoid the exposed area, thereby meeting the functional requirements while achieving targeted protection. Other functional layers can also be provided on other local areas of the conductive connection layer 17 according to other functional requirements.

[0046] The material of the bonding layer 14 can be any adhesive material with adhesive effect, such as polyimide glue, photoresist, or dry film. It should be noted that, since the process flow of the present application embodiment is to first set the bonding layer 14 and then set the release hole 16, the adhesive material does not need to consider whether it generates heat during the curing process after being coated, and can be adapted for use. Therefore, no specific limitation is made here. However, the present application embodiment will take the material of the bonding layer as an organic photosensitive material as an example for illustration, and should not be understood as a limitation on the material of the bonding layer 14.

[0047] The process of setting the bonding layer 14 on the side of the piezoelectric layer structure 12 away from the substrate 11 outside the first cavity 15 area includes coating the organic photosensitive material on the side of the piezoelectric layer structure 12 away from the substrate 11, and after curing, removing the organic photosensitive material above at least the first cavity 15 area to form the bonding layer 14.

[0048] In some embodiments, the PI glue is used to form the bonding layer 14 after the coating, developing, and exposing processes. By setting the bonding layer 14, the subsequent packaging of the cover 20 can be achieved, and the protection of the conductive connection layer 17 and the piezoelectric layer structure 12 can also be achieved.

[0049] In some embodiments, when the bonding layer 14 is set on the side of the conductive connection layer 17 away from the substrate 11, the packaging method further includes setting the bonding layer 14 on at least part of the peripheral of the conductive connection layer 17 and / or the piezoelectric layer structure 12. In this way, the etching liquid, cleaning liquid, and other chemical reagents in the subsequent process can be effectively prevented from penetrating into the inside of the conductive connection layer 17 and the piezoelectric layer structure 12, thereby avoiding the corrosion of the conductive circuit and the damage to the performance of the piezoelectric material.

[0050] In some embodiments, the whole resonator is tested before the bonding layer 14 is set. By testing the whole resonator before the bonding layer 14 is set, potential problems such as open / short circuit of the conductive connection layer 17, micro-cracks or contaminant residues on the surface of the substrate 11 can be accurately identified. In this way, unqualified devices can be detected before the packaging step, avoiding the waste of subsequent processes caused by the defects covered by the bonding layer 14, or the failure of the finished product due to defects.

[0051] In some embodiments, before the bonding layer 14 is set, a PAD process is used to deposit a dielectric layer on the whole resonator to protect the conductive connection layer 17 and the piezoelectric stack.

[0052] Please continue to refer to Figure 2 and Figure 5 , Figure 5 for Figure 1 the packaging method shown in the process diagram of the release hole, the specific process of forming the release hole 16 is as follows: 121. A patterned first mask is provided on the side of the bonding layer and the piezoelectric stack structure away from the substrate.

[0053] A photoresist is provided on the side of the bonding layer 14 and the piezoelectric stack structure 12, and a patterned first mask 19 is formed by exposing and developing the photoresist.

[0054] The pattern of the first mask 19 needs to match the position and size of the pre-set release hole 16, and needs to avoid the key functional areas of the bonding layer 14 and the piezoelectric stack structure 12, to ensure that etching only acts on the target area and avoids damage to other functional areas.

[0055] 122. The piezoelectric stack structure in the first cavity is etched according to the first mask to form a release hole that communicates with the first cavity.

[0056] According to the characteristics of the piezoelectric stack structure 12 material, dry etching or wet etching is selected: dry etching can achieve high anisotropy etching by adjusting the gas components such as CF4, Ar, etc., to ensure the size of the release hole 16; wet etching avoids over-etching by controlling the etching liquid concentration and time.

[0057] It should be noted that the depth needs to be monitored in real time during the etching process to ensure that the etching penetrates the piezoelectric stack structure 12 and communicates to the first cavity 15 below, neither under-etching to cause the release hole 16 not to be through, nor over-etching to avoid damaging the substrate 11 or other bottom layer structures at the bottom of the cavity.

[0058] 123. The first mask is removed.

[0059] According to the type of the first mask 19, a suitable removal method is selected: if it is a photoresist mask, wet stripping or plasma ashing can be used; if it is a hard mask, it can be removed by dissolving in a selective etching solution.

[0060] It should be noted that the removal process should avoid causing corrosion or physical damage to the bonding layer 14 and the surface of the piezoelectric stack structure 12, and after removing the first mask 19, the remaining mask debris or etching byproducts should be removed by cleaning to ensure that the inner wall of the release hole 16 and the surface of the device are clean, avoiding impurities blocking the release hole 16 or affecting the subsequent packaging steps.

[0061] By providing the release hole 16, gas flow between the first cavity 15 and the subsequently provided second cavity 25 can be achieved, effectively avoiding the generation of air pressure difference between the two due to environmental changes such as temperature fluctuations and external pressure changes, and avoiding the problems of cracking and peeling of the bonding layer 14 and the piezoelectric stack structure 12 due to uneven stress or stress.

[0062] In some embodiments, the packaging method further comprises providing a cover 20, packaging the cover 20 with the bonding layer 14 to form a second cavity 25, the second cavity 25 being in communication with the first cavity 15 through the release hole 16, after the bonding layer 14 is provided on the conductive connection layer 17, the bonding layer 14 can withstand the extrusion force of the roller during the packaging process. film acoustic device packaging process, effectively avoiding the risk of cracking of the conductive connection layer 17 or other bonding materials due to direct pressure. This design allows the cover 20 to be packaged with the bonding layer 14 using the film acoustic device packaging process, eliminating the need for additional buffer or protection structure (such as a second substrate) preparation steps in traditional processes. Not only does this simplify the process and reduce manufacturing costs, but it also reduces the thickness of the intermediate layer, ultimately achieving a reduction in the overall thickness of the packaged device without affecting the performance of the first cavity 15 and the second cavity 25.

[0063] Among them, the material of the cover 20 is an organic photosensitive material.

[0064] Please continue to refer to Figure 2 and Figure 6 , Figure 6 for Figure 1 The flowchart of the packaging method shown in the packaging method for setting the conductive interconnection layer, the packaging method further comprises the following steps: 140, forming a through hole through the cover and the bonding layer, the through hole exposing the conductive connection layer.

[0065] The through hole 21 can be formed by etching the cover 20 and the bonding layer 14 in sequence through exposure, development and etching processes. The etching process for forming the through hole 21 continues until the conductive connection layer 17 is exposed.

[0066] It should be noted that the position of the through hole 21 corresponds to the lead-out end of the conductive connection layer 17, so as to ensure that the subsequent conductive interconnection layer 22 can be precisely butted, and a reliable path is provided for the transmission of electrical signals.

[0067] 150. Forming a conductive interconnection layer on the surface of the through hole, the conductive interconnection layer being connected with the conductive connection layer.

[0068] The through hole 21 can be metallized by using processes including sputtering, electroplating, plasma physical vapor deposition, high-density plasma chemical vapor deposition, low-pressure chemical vapor deposition, atomic layer deposition, etc. to form the conductive interconnection layer 22 in the through hole 21. For example, a super-thin metal seed layer 24 is first deposited by sputtering to ensure that the side wall and the bottom of the through hole 21 are covered, and then electroplating is used to thicken the metal seed layer 24 to the target thickness, so as to ensure the conductive performance and structural strength of the interconnection layer. The conductive interconnection layer 22 formed needs to completely cover the inner wall and the bottom of the through hole 21 and the extended area on the surface of the cover 20, wherein the bottom is in contact with the exposed conductive connection layer 17, and the surface extended part serves as an external electrode pad, facilitating the connection with the packaging substrate or the test probe. By providing the through hole 21 on the bonding layer 14 and the cover 20 and providing the conductive interconnection layer 22 in the through hole 21, the first electrode 101 and the second electrode 103 in the piezoelectric stack can be connected with the external circuit through the conductive interconnection layer 22 and the conductive connection layer 17.

[0069] The material of the conductive interconnection layer 22 can be the same as that of the conductive connection layer 17, the second electrode 103 and the first electrode 101. In addition, in other embodiments of the present application, the material of the conductive interconnection layer 22 can include at least one of Ti, Ta, W, Mo, Cu, etc.

[0070] It should be noted that in some embodiments, if the material of the bonding layer 14 does not release heat when it is solidified, the piezoelectric stack structure 12 can be etched to form a release hole 16 communicating with the first cavity 15, and then the bonding layer 14 is arranged on the side of the piezoelectric stack structure 12 away from the substrate 11.

[0071] The embodiments of the present application also provide a thin film bulk acoustic resonator 1 obtained by the packaging method of any one of the above thin film bulk acoustic resonators 1, which comprises a resonant cavity main body structure, a bonding layer 14 and a release hole 16. The resonant cavity main body structure comprises a substrate 11 and a piezoelectric stack structure 12 arranged on the substrate 11, and a first cavity 15 is formed between the substrate 11 and the piezoelectric stack structure 12. The bonding layer 14 is arranged on the side of the piezoelectric stack structure 12 away from the substrate 11. The release hole 16 penetrates through the piezoelectric stack structure 12 to communicate with the first cavity 15.

[0072] Although the present application has been disclosed with reference to the above embodiments, the application is not limited to the above embodiments. It will be apparent to those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the application. The scope of the application should be limited only by the appended claims.

Claims

1. A method of packaging a film bulk acoustic resonator, the method comprising: The packaging method comprises: providing a resonant cavity main structure, the resonant cavity main structure comprising a substrate and a piezoelectric layer structure formed on the substrate, a first cavity being formed between the substrate and the piezoelectric layer structure; providing a bonding layer on the side of the piezoelectric layer structure away from the substrate outside the first cavity region, and then etching the piezoelectric layer structure to form a release hole communicating with the first cavity.

2. The packaging method according to claim 1, characterized in that, The piezoelectric layer structure comprises a first electrode, a piezoelectric layer and a second electrode arranged in sequence on the substrate, and before the bonding layer is provided outside the first cavity region, the method further comprises: providing a conductive connection layer on the piezoelectric layer structure outside the first cavity, The bonding layer covers at least part of the conductive connection layer.

3. The packaging method according to claim 2, characterized in that, The material of the bonding layer is an organic photosensitive material.

4. The packaging method according to claim 3, characterized in that, The method of providing a bonding layer on the side of the piezoelectric layer structure away from the substrate outside the first cavity region comprises: applying an organic photosensitive material to the side of the piezoelectric layer structure away from the substrate, and after the organic photosensitive material is cured, removing the organic photosensitive material above at least the first cavity region to form the bonding layer.

5. The packaging method according to claim 2, wherein, The packaging method further comprises: providing a cover, and bonding the cover with the bonding layer to form a second cavity, the second cavity communicating with the first cavity through the release hole.

6. The packaging method according to claim 5, characterized in that, The packaging method further comprises: forming a through hole through the cover and the bonding layer, the through hole exposing the conductive connection layer; forming a conductive interconnection layer on the surface of the through hole, the conductive interconnection layer being connected with the conductive connection layer.

7. The packaging method according to any one of claims 5 or 6, characterized in that, The material of the cover is an organic photosensitive material.

8. The packaging method of claim 1, wherein, The method of etching the piezoelectric layer structure to form a release hole communicating with the first cavity comprises: providing a patterned first mask on the side of the bonding layer and the piezoelectric layer structure away from the substrate; etching the piezoelectric layer structure in the first cavity according to the first mask to form a release hole communicating with the first cavity; removing the first mask.

9. The packaging method of claim 1, wherein, The method of providing a resonant cavity main structure comprises: providing a carrier substrate, and forming the piezoelectric layer structure and a support layer on the carrier substrate; etching the support layer to form the first cavity in the support layer; providing the substrate, and bonding the substrate to the side of the support layer away from the piezoelectric layer structure; removing the carrier substrate to form the resonant cavity main structure.

10. A film bulk acoustic resonator, characterized by, The film bulk acoustic resonator is obtained by the packaging method of any one of the film bulk acoustic resonators in claims 1 to 9, comprising: a resonant cavity main structure, the resonant cavity main structure comprising a substrate and a piezoelectric layer structure arranged on the substrate, a first cavity being formed between the substrate and the piezoelectric layer structure; a bonding layer provided on the side of the piezoelectric layer structure away from the substrate outside the first cavity region; a release hole passing through the piezoelectric layer structure to communicate with the first cavity.

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