A radio frequency filter device and a packaging method thereof

Abstract

The application discloses a radio frequency filter device and a packaging method thereof. The device comprises an external lead electrode and a first bonding filter and a second bonding filter which are stacked from bottom to top. The first bonding filter comprises a first base, a first support electrode on the upper surface of the first base, and a first bonding electrode on the upper surface of the first support electrode. The second bonding filter comprises a second base and a second bonding electrode on the lower surface of the second base, and the second bonding electrode has a recess. The cross-sectional size of the first bonding electrode is smaller than the cross-sectional size of the first support electrode and the size of the recess, and the first bonding electrode is bonded to the second bonding electrode through the recess. The external lead electrode is electrically connected to the second bonding electrode, the first bonding electrode, and an auxiliary bonding electrode in the second base through a through hole in the second base, so that the external lead electrode is electrically connected to the first bonding filter. The application can reduce the packaging cost of the radio frequency filter device, improve the production efficiency and integration.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a radio frequency filter device and its packaging method. Background Technology

[0002] With the rapid increase in the operating frequency of electronic devices, the frequency of electromagnetic interference is also getting higher and higher. These high-frequency interference signals have led to increasingly serious problems of radiated interference. Radio frequency (RF) filtering devices can significantly attenuate high-frequency radiated interference signals. Therefore, RF filtering devices are widely used in various electronic devices, especially consumer electronics.

[0003] For RF filter devices that include multiple chips, the current packaging process typically involves first packaging each chip individually, and then repackaging these individual chips using fan-out or other packaging methods to achieve multi-chip integration. This multiple packaging process not only results in high packaging costs but also long packaging cycles and low production efficiency. Furthermore, the existing package planar dimensions are relatively large, leading to low integration density in RF filter devices.

[0004] Therefore, how to solve the above-mentioned technical problems should be a key focus for those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a radio frequency filter device and its packaging method to reduce packaging costs, improve production efficiency, and increase device integration.

[0006] To address the aforementioned technical problems, this application provides a radio frequency filtering device, comprising: an external electrode and a first bonding filter and a second bonding filter stacked from bottom to top;

[0007] The first bonding filter includes a first substrate, a first support electrode located on the upper surface of the first substrate, and a first bonding electrode located on the upper surface of the first support electrode; the second bonding filter includes a second substrate and a second bonding electrode located on the lower surface of the second substrate, the second bonding electrode having a recess.

[0008] The cross-sectional dimension of the first bonding electrode is smaller than the cross-sectional dimension of the first supporting electrode and smaller than the dimension of the recess, and the first bonding electrode is bonded to the second bonding electrode through the recess;

[0009] The external electrode is electrically connected to the second bonding electrode, the first bonding electrode, and the auxiliary bonding electrode in the second substrate through a through hole located in the second substrate, so that the external electrode is electrically connected to the first bonding filter.

[0010] Optionally, when the first bonding electrode and the second bonding electrode are bonded using a eutectic bonding method, the method further includes:

[0011] The limiting electrode is located outside the second bonding electrode;

[0012] Accordingly, the second bonding electrode includes a first bonding sub-electrode and a second bonding sub-electrode stacked from bottom to top and each having a recess, and the first bonding sub-electrode and the second bonding sub-electrode are made of different materials.

[0013] Optionally, the limiting electrode is located around the second bonding electrode.

[0014] Optionally, the thickness of the first bonding electrode is greater than 2 micrometers.

[0015] Optionally, the thickness of the second bonding electrode is greater than 5 micrometers.

[0016] Optionally, the first bonding electrode and the second bonding electrode are bonded by thermo-pressing.

[0017] Optionally, there may be multiple second bonding filters, and the multiple second bonding filters may be stacked sequentially.

[0018] This application also provides a method for packaging radio frequency filter devices, including:

[0019] Obtain a first substrate and fabricate a first support electrode on the upper surface of the first substrate;

[0020] A first bonding electrode is fabricated on the upper surface of the first supporting electrode; the cross-sectional dimension of the first bonding electrode is smaller than the cross-sectional dimension of the first supporting electrode.

[0021] A second substrate is obtained, and a second bonding electrode with a recess is fabricated on the lower surface of the second substrate; the size of the recess is larger than the cross-sectional size of the first bonding electrode.

[0022] The first bonding electrode and the second bonding electrode are bonded together to obtain the bonded device;

[0023] Thin the second substrate and create through holes in the second substrate at positions corresponding to the auxiliary bonding electrodes;

[0024] An external electrode is fabricated in the through-hole so that the external electrode is electrically connected to the second bonding filter through the second bonding electrode, the first bonding electrode, and the auxiliary bonding electrode to obtain an RF filter device.

[0025] Optionally, when the first bonding electrode and the second bonding electrode are bonded using a eutectic bonding method, before fabricating the second bonding electrode with a recess on the lower surface of the second substrate, the method further includes:

[0026] A limiting electrode is fabricated on the lower surface of the second substrate;

[0027] Accordingly, fabricating a second bonding electrode with a recess on the lower surface of the second substrate includes:

[0028] A second bonding electrode is fabricated inside the confinement electrode;

[0029] A first bonded electrode is fabricated on the lower surface of the second bonded electrode, and the first bonded electrode and the second bonded electrode are made of different materials.

[0030] Optionally, the fabrication of the second bonding electrode inside the confining electrode includes:

[0031] The second bonding electrode is fabricated on the inner side of the confinement electrode using photolithography and electroplating.

[0032] This application provides a radio frequency filter device, including an external electrode and a first bonding filter and a second bonding filter stacked from bottom to top; the first bonding filter includes a first substrate, a first support electrode located on the upper surface of the first substrate, and a first bonding electrode located on the upper surface of the first support electrode; the second bonding filter includes a second substrate and a second bonding electrode located on the lower surface of the second substrate, the second bonding electrode having a recess; the cross-sectional dimension of the first bonding electrode is smaller than the cross-sectional dimension of the first support electrode and smaller than the dimension of the recess, the first bonding electrode being bonded to the second bonding electrode through the recess; the external electrode is electrically connected to the second bonding electrode, the first bonding electrode, and an auxiliary bonding electrode in the second substrate through a through-hole located in the second substrate, so that the external electrode is electrically connected to the first bonding filter.

[0033] As can be seen, the RF filter device of this application includes an external electrode, a first bonding filter, and a second bonding filter. The first bonding filter includes a first substrate, a first supporting electrode, and a first bonding electrode. The second bonding filter includes a second substrate and a second bonding electrode. The first and second bonding filters do not need to be packaged separately, which can save half of the chip-level packaging cost. The two are packaged together at the wafer level, which can effectively save half of the wafer-level packaging cost, reduce the packaging cycle, and improve production efficiency. The cross-sectional size of the first bonding electrode is smaller than the cross-sectional size of the first supporting electrode, that is, the first bonding electrode... The first bonding electrode and the first supporting electrode form a convex shape, and the cross-sectional dimension of the first bonding electrode is smaller than the concave dimension of the second bonding electrode, so the first bonding electrode and the second bonding electrode can be bonded. Since the external electrode is electrically connected to the second bonding electrode, the first bonding electrode, and the auxiliary bonding electrode in the second substrate through a through hole located in the second substrate, the external electrode is electrically connected to the first bonding filter, enabling the first bonding filter to achieve electrical connection with the outside. The first bonding filter and the second bonding filter are stacked and bonded in the vertical direction, which effectively reduces the size of the RF filter device on the plane and increases the integration density.

[0034] In addition, this application also provides a method for packaging radio frequency filter devices that has the above advantages. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A three-dimensional structural schematic diagram of a radio frequency filter device provided in an embodiment of this application;

[0037] Figure 2 The radio frequency filter device provided in the embodiments of this application is along Figure 1 Schematic diagram of section AA;

[0038] Figure 3 The radio frequency filter device provided in the embodiments of this application is along Figure 1 Schematic diagram of the structure of section BB;

[0039] Figure 4 This is a schematic diagram of the first substrate and a single chip in an embodiment of this application;

[0040] Figure 5 This is a schematic diagram of the second substrate and a single chip in an embodiment of this application;

[0041] Figure 6 This is a schematic diagram of the structure of the radio frequency filter device when the number of the second bonding filters in this application is two.

[0042] Figure 7 This is a flowchart illustrating a radio frequency filter device packaging method provided in an embodiment of this application;

[0043] Figures 8 to 19 This is a process flow diagram of the RF filter device packaging method when the first bonding electrode and the second bonding electrode are bonded by eutectic bonding in this application.

[0044] In the figure, 1 is the external electrode, 2 is the first substrate, 3 is the first supporting electrode, 4 is the first bonding electrode, 5 is the second substrate, 6 is the second bonding electrode, 7 is the confinement electrode, 8 is the via, 21 is the first wafer silicon substrate, 22 is the first piezoelectric film layer, 23 is the first functional electrode, 24 is the first sealing electrode, 25 is the first passivation layer, 26 is the first seed layer, 51 is the second wafer silicon substrate, 52 is the second piezoelectric film layer, 53 is the second functional electrode, 54 is the auxiliary bonding electrode, 55 is the second sealing electrode, 56 is the second passivation layer, 57 is the second seed layer, 58 is the second supporting electrode, 61 is the first bonding sub-electrode, and 62 is the second bonding sub-electrode. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0047] As described in the background section, current packaging methods typically involve individually packaging each chip first, and then repackaging these individual chips using fan-out or other packaging techniques to achieve multi-chip integration. This multiple packaging process not only results in high packaging costs but also long packaging cycles and low production efficiency. Furthermore, the large planar dimensions of existing packages lead to low integration density of RF filtering devices.

[0048] In view of this, this application provides a radio frequency filtering device, please refer to... Figure 1 , Figure 2 and Figure 3 , Figure 1 This is a three-dimensional structural schematic diagram of a radio frequency filter device provided in an embodiment of this application. Figure 2 The radio frequency filter device provided in the embodiments of this application is along Figure 1 Schematic diagram of section AA in the middle. Figure 3 The radio frequency filter device provided in the embodiments of this application is along Figure 1 A schematic diagram of the BB cross section shows that the RF filter device includes:

[0049] External electrode 1 and a first bonding filter and a second bonding filter stacked from bottom to top;

[0050] The first bonding filter includes a first substrate 2, a first support electrode 3 located on the upper surface of the first substrate 2, and a first bonding electrode 4 located on the upper surface of the first support electrode 3; the second bonding filter includes a second substrate 5 and a second bonding electrode 6 located on the lower surface of the second substrate 5, the second bonding electrode 6 having a recess.

[0051] The cross-sectional dimension of the first bonding electrode 4 is smaller than the cross-sectional dimension of the first supporting electrode 3 and smaller than the dimension of the recess. The first bonding electrode 4 is bonded to the second bonding electrode 6 through the recess.

[0052] The external electrode 1 is electrically connected to the second bonding electrode 6, the first bonding electrode 4, and the auxiliary bonding electrode 54 in the second substrate 5 through a through hole located in the second substrate 5, so that the external electrode 1 is electrically connected to the first bonding filter.

[0053] The material of the first bonding electrode 4 can be gold or copper, etc., and the material of the external electrode 1 can be copper or gold or other conductive materials. No specific limitation is made in this application.

[0054] The first substrate 2 and the single chip planar schematic diagram are shown below. Figure 4 As shown, the first substrate 2 includes a first wafer silicon substrate 21, a first piezoelectric film layer 22, a first functional electrode 23, a first sealing electrode 24, a first passivation layer 25, and a first seed layer 26. The first piezoelectric film layer 22 is connected to the first functional electrode 23, and the first functional electrode 23 is separated from the first sealing electrode 24. The first seed layer 26 corresponds to the first functional electrode 23 and the first sealing electrode 24.

[0055] The second substrate 5 and the single chip planar schematic diagram are shown below. Figure 5As shown, the second substrate 5 includes a second wafer silicon substrate 51, a second piezoelectric film layer 52, a second functional electrode 53, an auxiliary bonding electrode 54, a second sealing electrode 55, a second passivation layer 56, and a second seed layer 57. The second piezoelectric film layer 52, the auxiliary bonding electrode 54, and the second sealing electrode 55 are separated from each other. The region corresponding to the second piezoelectric film layer 52 in the second bonding filter is called the filter functional region, which is located inside the second sealing electrode 55 and consists of multiple resonators connected in series and parallel. Reference can be made to related RF filter devices, which will not be described in detail in this application.

[0056] The second piezoelectric film layer 52 corresponds to the position of the first piezoelectric film layer 22, the first sealing electrode 24 corresponds to the position of the second sealing electrode 55, the auxiliary bonding electrode 54 corresponds to the position of the first functional electrode 23, the first support electrode 3 corresponds to the first functional electrode 23 and the first sealing electrode 24 respectively, and the second bonding electrode 6 corresponds to the auxiliary bonding electrode 54 and the second sealing electrode 55 respectively. The via only penetrates the second wafer silicon substrate 51 in the second substrate 5, and the via corresponds to the auxiliary bonding electrode 54. Therefore, the external electrode 1 is electrically connected to the auxiliary bonding electrode 54, the second bonding electrode 6, and the first bonding electrode 4, thereby realizing the connection between the second bonding filter and the external electrode 1.

[0057] It should be noted that a through hole is also provided at the position of the second functional electrode 53 on the second wafer silicon substrate 51. The external electrode 1 is electrically connected to the second functional electrode 53 through the through hole, thereby realizing the connection between the second bonding filter and the external electrode 1.

[0058] The materials of the first seed layer 26 and the second seed layer 57 include, but are not limited to, titanium-tungsten alloy copper alloy, titanium-copper alloy, titanium-tungsten gold alloy, and titanium gold alloy. The thickness of the first seed layer 26 and the second seed layer 57 is between 3,000 angstroms and 10,000 angstroms.

[0059] The materials of the first supporting electrode 3, the auxiliary bonding electrode 54, the first sealing electrode 24, and the second sealing electrode 55 include, but are not limited to, copper, gold, nickel, and tin. The thickness of the first supporting electrode 3, the auxiliary bonding electrode 54, the first sealing electrode 24, and the second sealing electrode 55 is greater than 5 micrometers.

[0060] To prevent the second functional electrode 53 from being punctured during the fabrication of vias, the second bonding filter also includes a second support electrode 58 located on the lower surface of the second seed layer 57, corresponding to the second functional electrode 53. To ensure the support effect of the second support electrode 58, the thickness of the second support electrode 58 is greater than 5 micrometers.

[0061] The material of the second support electrode 58 includes, but is not limited to, copper, gold, tin, and nickel. The shape of the second support electrode 58 can be circular or polygonal, and this application does not impose a specific limitation. The planar area of ​​the second support electrode 58 is greater than 50um * 50um.

[0062] It should be noted that this application does not specifically limit the bonding method between the first bonding electrode 4 and the second bonding electrode 6, but depends on the circumstances. For example, the first bonding electrode 4 and the second bonding electrode 6 may be bonded by thermocompression bonding, adhesive bonding, or eutectic bonding. Adhesive bonding means that the first bonding electrode 4 and the second bonding electrode 6 are bonded by adhesive, while thermocompression bonding generally uses gold-to-gold thermocompression bonding.

[0063] When the first bonding electrode 4 and the second bonding electrode 6 are bonded using a eutectic bonding method, the method further includes:

[0064] The limiting electrode 7 is located outside the second bonding electrode 6;

[0065] Accordingly, the second bonding electrode 6 includes a first bonding sub-electrode 61 and a second bonding electrode 62 stacked from bottom to top and having recesses respectively, and the first bonding sub-electrode 61 and the second bonding electrode 62 are made of different materials.

[0066] The function of the limiting electrode 7 is to prevent the second bonding electrode 6 from melting and becoming amorphous on the surface of the second substrate 5 during molten bonding. The width of one side of the limiting electrode 7 is greater than 5 micrometers.

[0067] The height of the first bonding electrode 4 is greater than the height of the limiting electrode 7, and the planar dimension of the first bonding electrode 4 is smaller than the concave dimension of the auxiliary bonding electrode 54 and the second sealing electrode 55. The second bonding electrode 6 is positioned directly above the limiting electrode 7.

[0068] This application does not specifically limit the materials of the first bonding electrode 61 and the second bonding electrode 62, as long as they are eutectic metals. For example, the first bonding electrode 61 and the second bonding electrode 62 may be tin and copper, or tin and gold, or germanium and aluminum, etc.

[0069] It should be noted that this application does not specifically limit the number of second bonding filters; there can be one or more. When there are multiple second bonding filters, they are stacked sequentially. For example, if there are two second bonding filters, please refer to the schematic diagram of the RF filter device. Figure 6 .

[0070] The radio frequency filter device of this application includes an external electrode 1, a first bonding filter, and a second bonding filter. The first bonding filter includes a first substrate 2, a first support electrode 3, and a first bonding electrode 4. The second bonding filter includes a second substrate 5 and a second bonding electrode 6. The first and second bonding filters do not need to be packaged separately, which can save half of the chip-level packaging cost. The two are bonded together at the wafer level, which can effectively save half of the wafer-level packaging cost, reduce the packaging cycle, and improve production efficiency. The cross-sectional size of the first bonding electrode 4 is smaller than the cross-sectional size of the first support electrode 3, that is, the first bonding electrode 4 and the first support electrode 3 are bonded together. The first bonding electrode 4 is convex, and its cross-sectional dimension is smaller than that of the concave portion of the second bonding electrode 6. Therefore, the first bonding electrode 4 and the second bonding electrode 6 can be bonded. Since the external electrode 1 is electrically connected to the second bonding electrode 6, the first bonding electrode 4, and the auxiliary bonding electrode 54 in the second substrate 5 through a through hole located in the second substrate 5, the external electrode 1 is electrically connected to the first bonding filter, enabling the first bonding filter to achieve electrical connection with the outside. The first bonding filter and the second bonding filter are stacked and bonded in the vertical direction, which effectively reduces the size of the RF filter device on the plane, reduces the area by 40% to 50%, and increases the integration density.

[0071] When the first bonding electrode 4 and the second bonding electrode 6 are bonded using a eutectic bonding method, in order to better restrict the second bonding electrode 6 and prevent it from flowing in any direction when molten, the restricting electrode 7 is located around the second bonding electrode 6. In this case, the restricting electrode 7 is concave on the lower surface of the second substrate 5, that is, forming a dam around the second bonding electrode 6. However, this application does not specifically limit this. In other embodiments of this application, the restricting electrode 7 may also be located only on both sides of the second bonding electrode 6, that is, the restricting electrode 7 is L-shaped or V-shaped.

[0072] Based on the above embodiments, when the first bonding electrode 4 and the second bonding electrode 6 are bonded by eutectic bonding, in order to avoid the second bonding sub-electrode 62 being completely consumed during melting, the thickness of the second bonding sub-electrode 62 is greater than 5 micrometers.

[0073] To ensure that the first bonding electrode 61 and the first bonding electrode 4 are fused together, the thickness of the first bonding electrode 61 is greater than 2 micrometers.

[0074] It should be noted that the thickness of the first bonded electrode 61 should also be avoided from being too thick. If it is too thick, the first bonded electrode 61 will overflow after melting, causing a short circuit. The upper limit of the thickness of the first bonded electrode 61 depends on the volume limit electrode 7 and the first support electrode 3 after the first bonded electrode 61 and the second bonded electrode 62 are co-melted.

[0075] Please refer to Figure 7 This application also provides a method for packaging radio frequency filtering devices, the method comprising:

[0076] Step S101: Obtain a first substrate and fabricate a first support electrode on the upper surface of the first substrate.

[0077] Step S102: Fabricate a first bonding electrode on the upper surface of the first supporting electrode; the cross-sectional dimension of the first bonding electrode is smaller than the cross-sectional dimension of the first supporting electrode 3.

[0078] Step S103: Obtain a second substrate and fabricate a second bonding electrode with a recess on the lower surface of the second substrate; the size of the recess is larger than the cross-sectional size of the first bonding electrode.

[0079] Step S104: Bond the first bonding electrode and the second bonding electrode to obtain the bonded device.

[0080] It should be noted that this application does not specifically limit the bonding method between the first and second bonding electrodes, but depends on the circumstances. For example, the first and second bonding electrodes may be bonded by thermocompression bonding, adhesive bonding, or eutectic bonding. Adhesive bonding involves bonding the first and second bonding electrodes with adhesive, while thermocompression bonding typically uses gold-to-gold thermocompression bonding.

[0081] It should be noted that when the first bonding electrode and the second bonding electrode are bonded using a eutectic bonding method, before fabricating the second bonding electrode with a recess on the lower surface of the second substrate, the following steps are also included:

[0082] A limiting electrode is fabricated on the lower surface of the second substrate;

[0083] Accordingly, fabricating a second bonding electrode with a recess on the lower surface of the second substrate includes:

[0084] A second bonding electrode is fabricated inside the confinement electrode;

[0085] A first bonded electrode is fabricated on the lower surface of the second bonded electrode, and the first bonded electrode and the second bonded electrode are made of different materials.

[0086] In one specific embodiment, the fabrication of the second bonding electrode inside the confinement electrode includes:

[0087] The second bonding electrode is fabricated on the inner side of the confinement electrode using photolithography and electroplating.

[0088] Fabricating the first bonded electrode on the lower surface of the second bonded electrode includes:

[0089] The first bonded electrode is fabricated on the lower surface of the second bonded electrode using photolithography and electroplating.

[0090] Step S105: Thin the second substrate and create through holes in the second substrate at the positions corresponding to the auxiliary bonding electrodes.

[0091] It should be noted that a through-hole is also required at the position of the second functional electrode on the second wafer silicon substrate of the second substrate. The external electrode is electrically connected to the second functional electrode through the through-hole, thereby realizing the connection between the second bonding filter and the external electrode.

[0092] Step S106: An external electrode is prepared in the through hole so that the external electrode is electrically connected to the second bonding filter through the second bonding electrode, the first bonding electrode, and the auxiliary bonding electrode to obtain an RF filter device.

[0093] The RF filter device obtained by the RF filter device packaging method of this application includes an external electrode, a first bonding filter, and a second bonding filter. The first bonding filter includes a first substrate, a first support electrode, and a first bonding electrode. The second bonding filter includes a second substrate and a second bonding electrode. The first and second bonding filters do not need to be packaged separately; they are bonded together, which can effectively save packaging costs, reduce packaging cycle, and improve production efficiency. The cross-sectional dimension of the first bonding electrode is smaller than that of the first support electrode, i.e., the first bonding electrode and the first support electrode form a convex shape, and the cross-sectional dimension of the first bonding electrode is smaller than that of the concave portion of the second bonding electrode. Therefore, the first and second bonding electrodes can be bonded. Since the external electrode is electrically connected to the second bonding electrode, the first bonding electrode, and the auxiliary bonding electrode in the second substrate through a through-hole located in the second substrate, the external electrode is electrically connected to the first bonding filter, enabling the first bonding filter to achieve electrical connection with the outside. The first and second bonding filters are stacked and bonded in the vertical direction, which effectively reduces the size of the RF filter device on the plane and increases the integration density.

[0094] The following example illustrates the RF filter device packaging method in this application, using a co-fusion bonding method between the first and second bonding electrodes and one first and one second bonding filter.

[0095] Step 1: Prepare the first matrix precursor, such as... Figure 8 As shown, it includes a first wafer silicon substrate 21, a first piezoelectric film layer 22, a first functional electrode 23, a first sealing electrode 24, and a first passivation layer 25;

[0096] Step 2: Prepare a first seed layer 26 on the entire upper surface of the first substrate precursor using physical vapor deposition, such as... Figure 9 As shown;

[0097] Step 3: The first support electrode 3 is fabricated on the upper surface of the first seed layer 26 using photolithography and electroplating, such as... Figure 10 As shown; it should be emphasized that at this time, the first seed layer 26 is still a seed layer on the entire surface of the first substrate precursor;

[0098] Step 4: The first bonding electrode 4 is fabricated on the upper surface of the first supporting electrode 3 using photolithography and electroplating. Then, the first seed layer 26 that does not correspond to the first supporting electrode 3 is removed to obtain the first bonding filter. A cross-sectional schematic diagram is shown below. Figure 11 As shown, the top view is as follows Figure 12 As shown;

[0099] Step 5: Obtain the second matrix precursor, such as... Figure 13 As shown, it includes a second wafer silicon substrate 51, a second piezoelectric film layer 52, a second functional electrode 53, an auxiliary bonding electrode 54, a second sealing electrode 55, and a second passivation layer 56.

[0100] Step 6: Prepare a second seed layer 57 on the entire lower surface of the second substrate precursor using physical vapor deposition, such as... Figure 14 As shown;

[0101] Step 7: A confinement electrode 7 is fabricated on the lower surface of the second seed layer 57 using photolithography and electroplating. The width of one side of the confinement electrode 7 is greater than 5 micrometers. A cross-sectional schematic diagram is shown below. Figure 15 As shown; it should be emphasized that at this time, the second seed layer 57 is still a seed layer covering the entire surface of the second substrate precursor; and the second support electrode 58 on the lower surface of the second functional electrode 53, as shown Figure 16 As shown;

[0102] Step 8: A second bonding electrode 62 is fabricated inside the confinement electrode 7 using photolithography and electroplating, and a first bonding electrode 61 is fabricated on the lower surface of the second bonding electrode 62 to form the second bonding electrode 6. Then, the second seed layer 57 located outside the confinement electrode 7 is removed to obtain the second bonding filter, as shown below. Figure 17 As shown;

[0103] Step 9: Bond the first and second bonding filters together using wafer-level bonding to obtain the bonded device, as shown below. Figure 18 As shown;

[0104] Step 10: Thin the second wafer silicon substrate 51 by mechanical polishing to a thickness of 50-100 micrometers, and fabricate through-silicon vias (TSVs) in the regions corresponding to the auxiliary bonding electrodes 54, such as... Figure 19 As shown, a through hole 8 is prepared in the region corresponding to the second functional electrode 53; the size of the through hole 8 is smaller than the size of the second support electrode 58 and the auxiliary bonding electrode 54; considering the alignment and through hole drilling accuracy, the reserved area on one side is >20um;

[0105] Step 11: Fill the via 8 with metal using physical vapor deposition, photolithography, and electroplating to fabricate the external electrode 1, thus obtaining the radio frequency filter device, such as... Figure 2 As shown.

[0106] It should be noted that when the number of second bonding filters is two, after step 11 is completed, the process of preparing the second bonding filters in steps 5 to 8 is repeated. Then, the first bonding electrode is prepared again on the external electrode in step 11. The second bonding filter prepared again is then bonded to the first bonding electrode prepared again. Then, steps 10 to 11 are repeated to obtain... Figure 6 The structure is shown. When the number of second bonding filters is three or more, the fabrication and bonding process is the same as that of the second second bonding filter.

[0107] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0108] The radio frequency filtering devices and their packaging methods provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A radio frequency filter device, characterized by, The application relates to a piezoelectric filter, which comprises an outer lead electrode and a first bonding filter and a second bonding filter stacked from bottom to top. The first bonding filter comprises a first base, a first support electrode on the upper surface of the first base, and a first bonding electrode on the upper surface of the first support electrode; the second bonding filter comprises a second base and a second bonding electrode on the lower surface of the second base, and the second bonding electrode has a recess; The cross-sectional size of the first bonding electrode is smaller than the cross-sectional size of the first support electrode and smaller than the size of the recess, and the first bonding electrode is bonded with the second bonding electrode through the recess; The outer lead electrode is electrically connected with the second bonding electrode, the first bonding electrode and an auxiliary bonding electrode in the second base through a through hole in the second base, so that the outer lead electrode is electrically connected with the first bonding filter; The first base comprises a first wafer silicon substrate, a first piezoelectric film layer, a first functional electrode, a first sealing electrode, a first passivation layer and a first seed layer, the first piezoelectric film layer is connected with the first functional electrode, the first functional electrode and the first sealing electrode are separated from each other, and the first seed layer corresponds to the first functional electrode and the first sealing electrode; The second base comprises a second wafer silicon substrate, a second piezoelectric film layer, a second functional electrode, an auxiliary bonding electrode, a second sealing electrode, a second passivation layer and a second seed layer, the second piezoelectric film layer, the auxiliary bonding electrode and the second sealing electrode are separated from each other, and the second wafer silicon substrate is provided with a through hole at a position corresponding to the second functional electrode, and the outer lead electrode is electrically connected with the second functional electrode through the through hole; The second bonding filter further comprises a second support electrode on the lower surface of the second seed layer and corresponding to the second functional electrode. When the first bonding electrode and the second bonding electrode are bonded in a co-melting bonding mode, the piezoelectric filter further comprises a limiting electrode outside the second bonding electrode. Correspondingly, the second bonding electrode comprises a first bonding sub-electrode and a second bonding sub-electrode which are stacked from bottom to top and have recesses respectively, and the first bonding sub-electrode and the second bonding sub-electrode are made of different materials. The limiting electrode is located around the second bonding electrode. The thickness of the first bonding sub-electrode is greater than 2 microns.

2. The radio frequency filter device of claim 1, wherein, The thickness of the second bonding sub-electrode is greater than 5 microns.

3. The radio frequency filter device of claim 1, wherein, The first bonding electrode and the second bonding electrode are bonded in a hot-pressing bonding mode.

4. The radio frequency filter device of claim 1, wherein, The number of the second bonding filters is multiple, and the multiple second bonding filters are sequentially stacked.

5. The radio frequency filter device of claim 1, wherein, The application further relates to a piezoelectric filter manufacturing method, which comprises the following steps:

6. The radio frequency filter device of any one of claims 1 to 5, wherein, obtaining a first base and manufacturing a first support electrode on the upper surface of the first base; 7. A method for packaging radio frequency filter devices, characterized in that, manufacturing a first bonding electrode on the upper surface of the first support electrode; the cross-sectional size of the first bonding electrode is smaller than the cross-sectional size of the first support electrode; obtaining a second base and manufacturing a second bonding electrode with a recess on the lower surface of the second base; the size of the recess is greater than the cross-sectional size of the first bonding electrode; bonding the first bonding electrode and the second bonding electrode to obtain a bonded device; thinning the second base and manufacturing a through hole at a position corresponding to an auxiliary bonding electrode of the second base; ​ ​ An outer lead electrode is prepared in the through hole, so that the outer lead electrode is electrically connected with the second bonding electrode, the first bonding electrode, the auxiliary bonding electrode and the second bonding filter, to obtain a radio frequency filter device; The first substrate comprises a first wafer silicon substrate, a first piezoelectric film layer, a first functional electrode, a first sealing electrode, a first passivation layer and a first seed layer. The first piezoelectric film layer is connected with the first functional electrode. The first functional electrode and the first sealing electrode are separated from each other. The first seed layer corresponds to the first functional electrode and the first sealing electrode. The second substrate comprises a second wafer silicon substrate, a second piezoelectric film layer, a second functional electrode, an auxiliary bonding electrode, a second sealing electrode, a second passivation layer and a second seed layer. The second piezoelectric film layer, the auxiliary bonding electrode and the second sealing electrode are separated from each other. The second wafer silicon substrate is provided with a through hole at a position corresponding to the second functional electrode. An outer lead electrode is electrically connected with the second functional electrode through the through hole. The second bonding filter further comprises a second support electrode located at a lower surface of the second seed layer and corresponding to the second functional electrode. When the first bonding electrode and the second bonding electrode are bonded by a co-melting bonding method, before the second bonding electrode with a recess is prepared on the lower surface of the second substrate, the method further comprises: A limiting electrode is prepared on the lower surface of the second substrate. Correspondingly, the second bonding electrode with a recess is prepared on the lower surface of the second substrate, comprising: A second bonding sub-electrode is prepared inside the limiting electrode. A first bonding sub-electrode is prepared on a lower surface of the second bonding sub-electrode. The first bonding sub-electrode and the second bonding sub-electrode are made of different materials.

8. The radio frequency filter device packaging method of claim 7, wherein, The second bonding sub-electrode is prepared inside the limiting electrode, comprising: The second bonding sub-electrode is prepared inside the limiting electrode by using a photolithography and electroplating method. The second bonding sub-electrode is prepared inside the limiting electrode by using a photolithography and electroplating method.

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