Thin film bulk acoustic resonator with high power capability, method of fabrication and filter

Abstract

The application relates to the technical field of film bulk acoustic resonators, in particular to a film bulk acoustic resonator with high power capacity, a preparation method and a filter. The film bulk acoustic resonator comprises a support substrate, a heat conduction layer, a first electrode layer, a piezoelectric layer, a second electrode layer and a passivation layer which are sequentially stacked, the first local electrode layer and the heat conduction layer are connected with a first conductive pad, and the first conductive pad extends out of the support substrate; the second local electrode layer and the heat conduction layer are connected with a second conductive pad, and the second conductive pad extends out of the support substrate; the heat conduction layer is connected with a heat conduction pad, and the heat conduction pad extends out of the support substrate; the heat conduction pad is connected with the heat conduction layer and extends out of the support substrate, has strong heat dissipation capacity and large power capacity.

Description

Technical Field

[0001] This invention relates to the field of thin-film bulk acoustic wave resonators, and in particular to a thin-film bulk acoustic wave resonator with high power capacity, its fabrication method, and a filter. Background Technology

[0002] In the radio frequency (RF) front-end module of a wireless communication system, filters are an indispensable and crucial component. Their main function is to filter signals, thereby enabling signal reception and transmission. Common filters in mobile phones include surface acoustic wave (SAW) filters, solid-state assembled bulk acoustic wave (BAS) filters, and thin-film bulk acoustic wave (FBAR) filters. FBARs, as an emerging technology in recent years, and FBAR filters in general, are characterized by their small size, low insertion loss, high frequency, and high power capacity, making them highly suitable for next-generation high-frequency mobile terminal products.

[0003] FBAR consists of three main parts: a "sandwich" structure of metal thin film, piezoelectric material, and stacked metal thin film. Its working principle is based on the piezoelectric effect and inverse piezoelectric effect of piezoelectric material, which converts electrical signals into acoustic vibrations of piezoelectric material. Its resonant frequency is inversely proportional to the stack thickness in the vertical direction. Therefore, the working frequency of FBAR is controlled by the stack thickness. The higher the frequency, the thinner the stack structure.

[0004] In high-frequency FBAR products, the thickness of the "sandwich" structure is only tens to hundreds of nanometers. Reducing the stacking thickness not only increases the thin-film resistivity of the metal electrodes but also decreases the lattice quality of the deposited or sputtered piezoelectric material. The former increases the electrical losses of the FBAR, while the latter increases its acoustic losses, most of which are dissipated as heat. If this heat cannot be dissipated in time, FBAR overheating will not only limit its power capacity but also significantly reduce its lifespan, potentially leading to burnout. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a thin-film bulk acoustic resonator with high power capacity, a fabrication method and a filter.

[0006] The technical solution of the present invention for a thin-film bulk acoustic resonator with high power capacity is as follows:

[0007] The material includes a support substrate, a thermally conductive layer, a first electrode layer, a piezoelectric layer, a second electrode layer, and a passivation layer, which are stacked sequentially. The support substrate has a first groove, the thermally conductive layer is located on the surface of the first groove of the support substrate, and the thermally conductive layer covers each surface of the first groove.

[0008] The first electrode layer includes a first local electrode layer and a second local electrode layer that are separated from each other. The first local electrode layer is disposed on the opening of the first groove to form a first cavity, and the second local electrode layer is electrically connected to the second electrode layer.

[0009] The first local electrode layer and the thermally conductive layer are connected to a first conductive pad, and the first conductive pad extends beyond the supporting substrate. The second local electrode layer and the thermally conductive layer are connected to a second conductive pad, and the second conductive pad extends beyond the supporting substrate. The thermally conductive layer is connected to a thermally conductive pad, and the thermally conductive pad extends beyond the supporting substrate.

[0010] The beneficial effects of the thin-film bulk acoustic resonator with high power capacity of the present invention are as follows:

[0011] The first conductive pad, the second conductive pad, and the thermally conductive pad can promptly conduct the heat generated by the thin-film bulk acoustic wave resonator to the outside of the supporting substrate, thereby enhancing the heat dissipation capacity of the thin-film bulk acoustic wave resonator, increasing its power capacity, and reducing thermal damage to the thin-film bulk acoustic wave resonator. This results in a thin-film bulk acoustic wave resonator with high power capacity.

[0012] Based on the above scheme, the thin-film bulk acoustic resonator with high power capacity of the present invention can be further improved as follows.

[0013] Furthermore, a fifth via extending to the first local electrode layer is formed on the support substrate, the first conductive pad fills the fifth via and extends beyond the support substrate, and a second via extending to the second local electrode layer is formed on the support substrate, the second conductive pad fills the second via and extends beyond the support substrate.

[0014] Furthermore, it includes two thermally conductive pads, namely a first thermally conductive pad and a second thermally conductive pad. A third through-hole and a fourth through-hole extending to the thermally conductive layer are formed on the supporting substrate. The first thermally conductive pad fills the third through-hole and extends beyond the supporting substrate, and the second thermally conductive pad fills the fourth through-hole and extends beyond the supporting substrate.

[0015] The beneficial effect of adopting the above-mentioned further solution is to further enhance the heat dissipation capability of the thin-film bulk acoustic resonator.

[0016] Furthermore, the portion of the first thermally conductive pad extending beyond the support substrate is connected to the portion of the second thermally conductive pad extending beyond the support substrate.

[0017] The beneficial effect of adopting the above-mentioned further solution is to further enhance the heat dissipation capability of the thin-film bulk acoustic resonator.

[0018] Furthermore, the passivation layer covers one end of the second electrode layer and is connected to the piezoelectric layer, while the other end of the second electrode layer is electrically connected to the second local electrode layer.

[0019] Furthermore, a sealing layer is provided at the edge of the first electrode layer, the first electrode layer and the sealing layer are separated from each other, and the sealing layer is located between the thermally conductive layer and the piezoelectric layer.

[0020] Furthermore, it also includes a packaging cover plate with a second groove, the piezoelectric layer is covered on the opening of the second groove to form a second cavity, and the fourth metal layer, the passivation layer and the second electrode layer are all located in the second cavity, and the fourth metal layer, the passivation layer and the second electrode layer are not in contact with the packaging cover plate.

[0021] Furthermore, the thermal conductive layer is made of diamond.

[0022] The beneficial effect of adopting the above-mentioned further solution is that diamond has high thermal conductivity, which further enhances the heat dissipation capacity of the thin-film bulk acoustic resonator.

[0023] The technical solution of the present invention for fabricating a thin-film bulk acoustic resonator with high power capacity is as follows:

[0024] A first groove is formed on a support substrate, and a thermally conductive layer is formed on the surface of the first groove on the support substrate, and the thermally conductive layer covers each surface of the first groove;

[0025] A seed layer and a piezoelectric layer are sequentially fabricated on a transfer substrate. A first metal layer is fabricated on the piezoelectric layer and patterned to obtain a first electrode layer. A sealing layer is fabricated at the edge of the first electrode layer, and the first electrode layer and the sealing layer are separated from each other. The first electrode layer includes a first local electrode layer and a second local electrode layer that are separated from each other.

[0026] The first local electrode layer is applied to the opening of the first groove to form a first cavity, and the sealing layer is located between the thermally conductive layer and the piezoelectric layer.

[0027] Remove the seed layer and the transfer substrate, prepare a second metal layer on the piezoelectric layer, and pattern it to obtain a second electrode layer;

[0028] A passivation layer is prepared on the second electrode layer, the passivation layer covers one end of the second electrode layer and is connected to the piezoelectric layer, and the other end of the second electrode layer is electrically connected to the second local electrode layer.

[0029] The second local electrode layer is electrically connected to the second electrode layer, and a first through hole extending to the first local electrode layer is formed on the piezoelectric layer. A fourth metal layer is deposited in the first through hole, and the fourth metal layer extends beyond the piezoelectric layer and is not in contact with the passivation layer.

[0030] A packaging cover plate with a second groove is prepared, and the piezoelectric layer is applied to the opening of the second groove to form a second cavity. The fourth metal layer, the passivation layer and the second electrode layer are all located in the second cavity, and the fourth metal layer, the passivation layer and the second electrode layer are not in contact with the packaging cover plate.

[0031] A first conductive pad is prepared for connecting the first local electrode layer and the thermally conductive layer, and the first conductive pad extends beyond the supporting substrate. A second conductive pad is prepared for connecting the second local electrode layer and the thermally conductive layer, and the second conductive pad extends beyond the supporting substrate. A thermally conductive pad is prepared for connecting the thermally conductive layer, and the thermally conductive pad extends beyond the supporting substrate.

[0032] The beneficial effects of the method for fabricating a thin-film bulk acoustic resonator with high power capacity according to the present invention are as follows:

[0033] On the one hand, the traditional FBAR process eliminates the step of filling the substrate groove before releasing the sacrificial layer, making the fabrication process simpler. On the other hand, the heat generated by the thin-film bulk acoustic wave resonator can be promptly discharged to the outside of the supporting substrate through the first conductive pad, the second conductive pad, and the thermally conductive pad, thereby enhancing the heat dissipation capacity of the thin-film bulk acoustic wave resonator, increasing the power capacity of the thin-film bulk acoustic wave resonator, and reducing thermal damage to the thin-film bulk acoustic wave resonator. Thus, a thin-film bulk acoustic wave resonator with high power capacity is fabricated.

[0034] The present invention provides a thin-film bulk acoustic wave filter, comprising a thin-film bulk acoustic wave resonator as described in any of the preceding claims. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the cross-sectional structure of a thin-film bulk acoustic resonator according to an embodiment of the present invention;

[0036] Figure 2This is a schematic flowchart of a method for fabricating a thin-film bulk acoustic resonator with high power capacity according to an embodiment of the present invention.

[0037] Figure 3 A schematic diagram of the cross-sectional structure after the first groove is formed on the support substrate;

[0038] Figure 4 This is a schematic diagram of the cross-sectional structure after the thermally conductive layer has been fabricated.

[0039] Figure 5 A schematic diagram of the cross-sectional structure after the seed layer is prepared on the transfer substrate;

[0040] Figure 6 This is a schematic diagram of the structure after the piezoelectric layer is fabricated on the seed layer;

[0041] Figure 7 This is a schematic diagram of the cross-sectional structure after the first electrode layer has been fabricated;

[0042] Figure 8 This is a schematic diagram of the structure after the sealing layer has been prepared;

[0043] Figure 9 This is a schematic diagram of the cross-sectional structure after the support substrate and the transfer substrate are combined.

[0044] Figure 10 A schematic diagram of the cross-sectional structure after removing the transfer substrate and seed layer;

[0045] Figure 11 This is a schematic diagram of the cross-sectional structure after the second electrode layer has been fabricated;

[0046] Figure 12 This is a schematic diagram of the cross-sectional structure after the passivation layer has been prepared.

[0047] Figure 13 A schematic diagram of the cross-sectional structure after the fabrication of the third metal layer;

[0048] Figure 14 This is a schematic diagram of the cross-sectional structure after the encapsulation cover has been installed;

[0049] Figure 15 This is a schematic diagram of the cross-sectional structure after the first, second, third, and fourth through holes are opened.

[0050] The attached diagram lists the components represented by each number as follows:

[0051] 10. Supporting substrate; 11. First groove; 110. First cavity; 12. Thermally conductive layer; 13. Transfer substrate; 14. Seed layer; 15. Piezoelectric layer; 16. First electrode layer; 161. First local electrode layer; 162. Second local electrode layer; 17. Sealing layer; 18. Second electrode layer; 19. Passivation layer; 20. Third metal layer; 21. Encapsulation cover plate; 22. Second through hole; 23. Third through hole; 24. Fourth through hole; 25. Fifth through hole; 26. Second cavity; 27. Second conductive pad; 28. First thermally conductive pad; 29. ​​Second thermally conductive pad; 30. First conductive pad; 31. Fourth metal layer. Detailed Implementation

[0052] like Figure 1 As shown, a thin-film bulk acoustic resonator with high power capacity according to an embodiment of the present invention includes a support substrate 10, a thermally conductive layer 12, a first electrode layer 16, a piezoelectric layer 15, a second electrode layer 18, and a passivation layer 19 stacked sequentially. The support substrate 10 is provided with a first groove 11, and the thermally conductive layer 12 is located on the surface of the first groove 11 of the support substrate 10, and the thermally conductive layer 12 covers each surface of the first groove 11.

[0053] The first electrode layer 16 includes a first local electrode layer 161 and a second local electrode layer 162 that are separated from each other. The first local electrode layer 161 is disposed on the opening of the first groove 11 to form a first cavity 110. The second local electrode layer 162 is electrically connected to the second electrode layer 18.

[0054] The first local electrode layer 161 and the thermal conductive layer 12 are connected to the first conductive pad 30, and the first conductive pad 30 extends beyond the support substrate 10. The second local electrode layer 162 and the thermal conductive layer 12 are connected to the second conductive pad 27, and the second conductive pad 27 extends beyond the support substrate 10. The thermal conductive layer 12 is connected to the thermal conductive pad, and the thermal conductive pad extends beyond the support substrate 10.

[0055] The piezoelectric layer 15 has a first through hole extending to the first local electrode layer 161. A fourth metal layer 31 is provided in the first through hole and extends beyond the piezoelectric layer 15. The fourth metal layer 31 is not in contact with the passivation layer 19. The fourth metal layer 31 is used for electrical performance testing before packaging.

[0056] The material of the supporting substrate 10 is a common substrate material in semiconductor processes, including but not limited to silicon (Si), germanium (Ge), sapphire (Al2O3), quartz (SiO2), silicon carbide (SiC), organic polymers, etc.

[0057] The thermal conductive layer 12 is made of diamond. Diamond has high thermal conductivity, which further enhances the heat dissipation capacity of the thin-film bulk acoustic resonator. The material of the thermal conductive layer 12 can also be set according to the actual situation.

[0058] The first electrode layer 16 and the second electrode layer 18 are made of metal materials with good electrical conductivity, including but not limited to molybdenum (Mo), copper (Cu), tungsten (W), gold (Au), titanium (Ti), aluminum (Al), platinum (Pt), etc.

[0059] The piezoelectric layer 15 is made of piezoelectric materials, including but not limited to aluminum nitride (AlN), lithium niobate (LiNbO3), and lithium tantalate (LiTaO3).

[0060] The passivation layer 19 is made of materials such as silicon dioxide (SiO2) and aluminum nitride (AlN).

[0061] The first groove 11 has a trapezoidal cross section, but it can also be set to other shapes depending on the actual situation.

[0062] The electrical connection between the second local electrode layer 162 and the second electrode layer 18 is achieved as follows:

[0063] Etching is performed on the piezoelectric layer 15 to expose the second local electrode layer 162. Then, metal is deposited to form a third metal layer 20, which covers one end of the second electrode layer 18. The third metal layer 20 enables electrical connection between the second local electrode layer 162 and the second electrode layer 18. The material of the third metal layer 20 is at least one of copper, tungsten, gold, titanium, aluminum, and silver.

[0064] Specifically, a fifth through-hole 25 extending to the first local electrode layer 161 is formed on the support substrate 10, and a first conductive pad 30 fills the fifth through-hole 25 and extends beyond the support substrate 10. A second through-hole 22 extending to the second local electrode layer 162 is formed on the support substrate 10, and a second conductive pad 27 fills the second through-hole 22 and extends beyond the support substrate 10.

[0065] The specific structure of the first conductive pad 30 is as follows: a fifth through hole 25 extending to the first local electrode layer 161 is opened on the support substrate 10, that is, the first local electrode layer 161 is exposed in the fifth through hole 25, and metals such as copper, tungsten, gold, titanium, aluminum or silver are deposited in the fifth through hole 25 and extended beyond the support substrate 10. The metal deposited in the fifth through hole 25 and the metal extended beyond the support substrate 10 constitute the first conductive pad 30.

[0066] The specific structure of the second conductive pad 27 is as follows: a second through hole 22 extending to the second local electrode layer 162 is opened on the support substrate 10, that is, the second local electrode layer 162 is exposed in the second through hole 22, and metals such as copper, tungsten, gold, titanium, aluminum or silver are deposited in the second through hole 22, and the metals deposited in the fourth through hole 24 and the metals extending outside the support substrate 10 are deposited, which constitute the second conductive pad 27.

[0067] The specific structure of the thermally conductive pad is as follows: a through hole is opened on the support substrate 10 until the thermally conductive layer 12 is exposed, and metals such as copper, tungsten, gold, titanium, aluminum or silver are deposited in the through hole and extend beyond the support substrate 10. The metal deposited in the through hole and the metal extending beyond the support substrate 10 are the thermally conductive pads. Multiple conductive pads and multiple thermally conductive pads can be set according to the actual situation.

[0068] The conductive pads and thermal pads are made of copper, tungsten, gold, titanium, aluminum, or silver.

[0069] The fourth metal layer 31 is disposed opposite to the first conductive pad 30 on both sides of the first local electrode layer 161, and the third metal layer 20 is disposed opposite to the second conductive pad 27 on both sides of the second local electrode layer 162.

[0070] The first conductive pad 30, the second conductive pad 27, and the first thermally conductive pad 28 and the second thermally conductive pad 29 (described below) can promptly conduct the heat generated by the thin-film bulk acoustic wave resonator to the outside of the supporting substrate 10, thereby enhancing the heat dissipation capacity of the thin-film bulk acoustic wave resonator, increasing the power capacity of the thin-film bulk acoustic wave resonator, and reducing thermal damage to the thin-film bulk acoustic wave resonator. This results in a thin-film bulk acoustic wave resonator with high power capacity.

[0071] Optionally, in the above technical solution, a sealing layer 17 is provided at the edge of the first electrode layer 16, the first electrode layer 16 and the sealing layer 17 are separated from each other, and the sealing layer 17 is located between the thermally conductive layer 12 and the piezoelectric layer 15. The sealing layer 17 is made of epoxy resin with good sealing properties or a soft metal such as gold (Au).

[0072] Optionally, in the above technical solution, two thermally conductive pads are included, namely a first thermally conductive pad 28 and a second thermally conductive pad 29. A third through-hole 23 and a fourth through-hole 24 extending to the thermally conductive layer 12 are formed on the supporting substrate 10. The first thermally conductive pad 28 fills the third through-hole 23 and extends beyond the supporting substrate 10, and the second thermally conductive pad 29 fills the fourth through-hole 24 and extends beyond the supporting substrate 10. The specific implementation of the first thermally conductive pad 28 and the second thermally conductive pad 29 is as follows:

[0073] A third via 23 and a fourth via 24 are formed on the support substrate 10 until the thermally conductive layer 12 is exposed. Metals such as copper, tungsten, gold, titanium, aluminum or silver are deposited in the third via 23 and the fourth via 24 and extend beyond the support substrate 10. The metal deposited in the third via 23 and the metal extending beyond the support substrate 10 are the first thermally conductive pad 28. The metal deposited in the fourth via 24 and the metal extending beyond the support substrate 10 are the second thermally conductive pad 29.

[0074] Optionally, in the above technical solution, the portion of the first thermally conductive pad 28 extending beyond the support substrate 10 is connected to the portion of the second thermally conductive pad 29 extending beyond the support substrate 10, and the area after connection is slightly larger than the first cavity 110.

[0075] Optionally, in the above technical solution, the passivation layer 19 covers one end of the second electrode layer 18, and the passivation layer 19 is connected to the piezoelectric layer 15, while the other end of the second electrode layer 18 is electrically connected to the second local electrode layer 162. That is, the two ends of the second electrode layer 18 are respectively covered with the passivation layer 19 and the third metal layer 20.

[0076] Optionally, the above technical solution also includes a packaging cover plate 21 with a second groove, a piezoelectric layer 15 covering the opening of the second groove to form a second cavity 26, and the fourth metal layer 31, the passivation layer 19 and the second electrode layer 18 are all located in the second cavity 26, and the fourth metal layer 31, the passivation layer 19 and the second electrode layer 18 are not in contact with the packaging cover plate 21.

[0077] The packaging cover 21 is made of a common substrate material used in semiconductor processes, including but not limited to silicon (Si), germanium (Ge), sapphire (Al2O3), quartz (SiO2), silicon carbide (SiC), organic polymers, etc. The packaging cover 2121 serves a protective function.

[0078] The second groove has a rectangular cross-section, but it can be made into other shapes depending on the actual situation.

[0079] like Figure 2 As shown, an embodiment of the present invention provides a method for fabricating a thin-film bulk acoustic resonator with high power capacity, comprising:

[0080] S1. A first groove 11 is formed on the support substrate 10, and a thermally conductive layer 12 is formed on the surface of the first groove 11 of the support substrate 10, and the thermally conductive layer 12 covers each surface of the first groove 11.

[0081] S2. A seed layer 14 and a piezoelectric layer 15 are sequentially prepared on the transfer substrate 13. A first metal layer is prepared on the piezoelectric layer 15 and patterned to obtain a first electrode layer 16. A sealing layer 17 is prepared at the edge of the first electrode layer 16, and the first electrode layer 16 and the sealing layer 17 are separated from each other. The first electrode layer 16 includes a first local electrode layer 161 and a second local electrode layer 162 that are separated from each other.

[0082] S3. The first local electrode layer 161 is applied to the opening of the first groove 11 to form the first cavity 110, and the sealing layer 17 is located between the heat-conducting layer 12 and the piezoelectric layer 15.

[0083] S4. Remove the seed layer 14 and the transfer substrate 13, prepare a second metal layer on the piezoelectric layer 15, and pattern it to obtain the second electrode layer 18.

[0084] S5. A passivation layer 19 is prepared on the second electrode layer 18. The passivation layer 19 covers one end of the second electrode layer 18 and is connected to the piezoelectric layer 15. The other end of the second electrode layer 18 is electrically connected to the second local electrode layer 162.

[0085] S6. The second local electrode layer 162 is electrically connected to the second electrode layer 18, and a first through hole extending to the first local electrode layer 161 is opened on the piezoelectric layer 15. A fourth metal layer 31 is deposited in the first through hole, and the fourth metal layer 31 extends beyond the piezoelectric layer 15 and is not in contact with the passivation layer 19.

[0086] S7. Prepare a packaging cover plate 21 with a second groove, so that the piezoelectric layer 15 covers the opening of the second groove to form a second cavity 26. The fourth metal layer 31, the passivation layer 19 and the second electrode layer 18 are all located in the second cavity 26, and the fourth metal layer 31, the passivation layer 19 and the second electrode layer 18 are not in contact with the packaging cover plate 21.

[0087] S7. Prepare a first conductive pad 30 for connecting the first local electrode layer 161 and the thermal conductive layer 12, with the first conductive pad 30 extending beyond the support substrate 10; prepare a second conductive pad 27 for connecting the second local electrode layer 162 and the thermal conductive layer 12, with the second conductive pad 27 extending beyond the support substrate 10; prepare a thermally conductive pad for connecting the thermal conductive layer 12, with the thermally conductive pad extending beyond the support substrate 10.

[0088] On the one hand, the traditional FBAR process eliminates the step of filling the substrate groove before releasing the sacrificial layer, making the fabrication process simpler. On the other hand, the heat generated by the thin-film bulk acoustic wave resonator can be promptly discharged to the outside of the supporting substrate 10 through the first conductive pad 30, the second conductive pad 27 and the thermally conductive pad, enhancing the heat dissipation capacity of the thin-film bulk acoustic wave resonator, increasing the power capacity of the thin-film bulk acoustic wave resonator, and reducing thermal damage to the thin-film bulk acoustic wave resonator. Thus, a thin-film bulk acoustic wave resonator with high power capacity is fabricated.

[0089] The following examples illustrate a method for fabricating a thin-film bulk acoustic resonator with high power capacity according to the present invention. Specifically:

[0090] S10. Open the first groove 11, specifically:

[0091] like Figure 3 As shown, a first groove 11 of a certain depth is formed on the support substrate 10 by photolithography and etching processes. The depth can be set according to the actual situation.

[0092] S11. Prepare the thermally conductive layer 12, specifically:

[0093] like Figure 4 As shown, a thermally conductive layer 12 of a certain thickness is grown on the support substrate 10 using sputtering or chemical vapor deposition methods. The thickness can be set according to the actual situation. At this time, the thermally conductive layer 12 covers the surface of the first groove 11 of the support substrate 10, and the thermally conductive layer 12 covers each surface of the first groove 11.

[0094] S12. Prepare seed layer 14, specifically:

[0095] like Figure 5 As shown, a seed layer 14 for growing piezoelectric materials is prepared on the transfer substrate 13;

[0096] S13, Prepare piezoelectric layer 15, specifically:

[0097] like Figure 6 As shown, a piezoelectric material is grown on the seed layer 14 by sputtering or chemical vapor deposition to form a piezoelectric layer 15 of a certain thickness. The thickness of the piezoelectric layer 15 can be set according to the actual situation.

[0098] S14. Prepare the first electrode layer 16, specifically:

[0099] like Figure 7As shown, a first metal layer is fabricated on the piezoelectric layer 15 and patterned. Specifically, the first metal layer is patterned through photolithography, etching and other processes to obtain a first electrode layer 16. The first electrode layer 16 includes a first local electrode layer 161 and a second local electrode layer 162 that are separated from each other.

[0100] S15. Prepare sealing layer 17, specifically:

[0101] like Figure 8 As shown, a sealing layer 17 for wafer bonding is sprayed or deposited at the edge of the first electrode layer 16, and the first electrode layer 16 and the sealing layer 17 are not in contact, that is, the first local electrode layer 161 and the second local electrode layer 162 are not in contact with the sealing layer 17.

[0102] S16. Form the first cavity 110, specifically:

[0103] like Figure 9 As shown, the transfer substrate 13 and the support substrate 10 are placed face to face, and the sealing layer 17 and the piezoelectric layer 15 are wafer bonded so that the first local electrode layer 161 completely covers the opening of the first groove 11, forming the first cavity 110, and the sealing layer 17 is located between the thermally conductive layer 12 and the piezoelectric layer 15.

[0104] S17, Remove seed layer 14 and transfer substrate 13, as follows Figure 10 As shown;

[0105] S18. Prepare the second electrode layer 18, specifically:

[0106] like Figure 11 As shown, a second metal layer is prepared on the surface of the piezoelectric layer 15 by deposition, and the second metal layer is patterned by photolithography, etching and other processes to form the second electrode layer 18.

[0107] S19, Prepare passivation layer 19, specifically:

[0108] like Figure 12 As shown, a passivation layer 19 is prepared on the second electrode layer 18. The passivation layer 19 covers one end of the second electrode layer 18 and is connected to the piezoelectric layer 15. The other end of the second electrode layer 18 is electrically connected to the second local electrode layer 162. That is, a part of the passivation layer 19 is covered on the piezoelectric layer 15, and another part of the passivation layer 19 covers one end of the second electrode layer 18. The part of the second electrode layer 18 that is not covered by the passivation layer 19 is electrically connected to the second local electrode layer 162.

[0109] The passivation layer 19 is used to protect or trim the operating frequency of the thin-film bulk acoustic resonator, and the sealing layer 17 is located between the thermally conductive layer 12 and the piezoelectric layer 15.

[0110] S20. Electrically connect the second local electrode layer 162 and the second electrode layer 18. Etch away the piezoelectric layer 15 in the area where the second local electrode layer 162 and the second electrode layer 18 need to be connected on the piezoelectric layer 15, and deposit metal to obtain a third metal layer 20. The electrical connection between the second local electrode layer 162 and the second electrode layer 18 is achieved through the third metal layer 20. Figure 13 As shown.

[0111] S21, Prepare the fourth metal layer 31, specifically:

[0112] Etching is performed on the piezoelectric layer 15 to expose the first local electrode layer 161, and then metal is deposited to form a fourth metal layer 31, wherein the fourth metal layer 31 is not in contact with the passivation layer 19.

[0113] S22. Prepare a packaging cover plate 21 with a second groove, so that the piezoelectric layer 15 covers the opening of the second groove to form a second cavity 26. The fourth metal layer 31, the passivation layer 19, and the second electrode layer 18 are all located within the second cavity 26, and the fourth metal layer 31, the passivation layer 19, and the second electrode layer 18 are not in contact with the packaging cover plate 21. The packaging cover plate 21 protects the front side of the device. Figure 14 As shown;

[0114] S23. Prepare the first conductive pad 30, the second conductive pad 27, the first thermally conductive pad 28, and the second thermally conductive pad 29, specifically:

[0115] 1) A fifth via 25 extending to the first local electrode layer 161 is formed on the support substrate 10, that is, the first local electrode layer 161 is exposed in the fifth via 25. Metals such as copper, tungsten, gold, titanium, aluminum or silver are deposited in the fifth via 25 and extended beyond the support substrate 10. The metal deposited in the fifth via 25 and the metal extended beyond the support substrate 10 are the first conductive pad 30.

[0116] 2) The specific structure of the second conductive pad 27 is as follows: a second through hole 22 extending to the second local electrode layer 162 is opened on the support substrate 10, that is, the second local electrode layer 162 is exposed in the second through hole 22, and metals such as copper, tungsten, gold, titanium, aluminum or silver are deposited in the second through hole 22 and deposited to extend beyond the support substrate 10. The metal deposited in the fourth through hole 24 and the metal extending beyond the support substrate 10 are the second conductive pad 27.

[0117] 3) A third via 23 and a fourth via 24 are made on the support substrate 10 until the thermal conductive layer 12 is exposed. Metals such as copper, tungsten, gold, titanium, aluminum or silver are deposited in the third via 23 and the fourth via 24 and extend beyond the support substrate 10. The metal deposited in the third via 23 and the metal extending beyond the support substrate 10 are the first thermal conductive pad 28. The metal deposited in the fourth via 24 and the metal extending beyond the support substrate 10 are the second thermal conductive pad 29.

[0118] Among them, the first conductive pad 30 and the second conductive pad 27 play the roles of electrical conductivity and thermal conductivity, while the first thermally conductive pad 28 and the second thermally conductive pad 29 play the role of thermal conductivity.

[0119] In this configuration, the portion of the first thermally conductive pad 28 extending beyond the support substrate 10 is connected to the portion of the second thermally conductive pad 29 extending beyond the support substrate 10. The area after the connection is slightly larger than the first cavity 110, thus achieving the following... Figure 1 The image shows a thin-film bulk acoustic resonator with high power capacity.

[0120] Currently, enhancing the heat dissipation capacity of devices and improving thin film quality are key issues in increasing power capacity. Compared with existing structures and fabrication techniques, this invention utilizes the growth and transfer technology of single-crystal piezoelectric thin films and a special thermally conductive encapsulation technology to optimize the structure and fabrication method of bulk acoustic wave resonators and filters. The key technical points and advantages of this method are: higher lattice quality of the single-crystal piezoelectric thin film and lower acoustic wave loss; elimination of the sacrificial layer, significantly reducing process steps; and a special thermally conductive encapsulation structure that enhances the heat dissipation capacity of the device, thereby increasing its power capacity.

[0121] This invention can introduce a new structure during packaging to enhance the heat dissipation capacity of the device and improve the power capacity of the filter; at the same time, the method of transferring the single crystal piezoelectric thin film can not only ensure the lattice quality of the piezoelectric material and reduce acoustic wave loss, but also eliminate the process of filling and releasing the air cavity.

[0122] The present invention provides a thin-film bulk acoustic wave filter, comprising a thin-film bulk acoustic wave resonator according to any one of the above claims.

[0123] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0124] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0125] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A thin film bulk acoustic resonator having a high power capacity, characterized by, The piezoelectric layer is formed on the first electrode layer, and the second electrode layer is formed on the piezoelectric layer. The first electrode layer comprises a first partial electrode layer and a second partial electrode layer which are separated from each other, the first partial electrode layer covers the opening of the first recess to form a first cavity, and the second partial electrode layer is electrically connected with the second electrode layer. The first partial electrode layer and the heat-conducting layer are connected with a first conductive pad which extends out of the support substrate, the second partial electrode layer and the heat-conducting layer are connected with a second conductive pad which extends out of the support substrate, and the heat-conducting layer is connected with a heat-conducting pad which extends out of the support substrate. A fifth through hole extending to the first partial electrode layer is formed on the support substrate, the first conductive pad fills the fifth through hole and extends out of the support substrate, and a second through hole extending to the second partial electrode layer is formed on the support substrate, the second conductive pad fills the second through hole and extends out of the support substrate. The second partial electrode layer is electrically connected with the second electrode layer in the following manner: The piezoelectric layer is etched to expose the second partial electrode layer, then metal is deposited to form a third metal layer which covers one end of the second electrode layer, and the third metal layer is used to electrically connect the second partial electrode layer with the second electrode layer. The support substrate is provided with a third through hole and a fourth through hole extending to the heat-conducting layer, the first heat-conducting pad fills the third through hole and extends out of the support substrate, and the second heat-conducting pad fills the fourth through hole and extends out of the support substrate. The structure of the first conductive pad is that a fifth through hole extending to the first partial electrode layer is formed on the support substrate, the first partial electrode layer is exposed in the fifth through hole, metal is deposited in the fifth through hole and extends out of the support substrate, and the metal deposited in the fifth through hole and extending out of the support substrate is the first conductive pad. The structure of the second conductive pad is that a second through hole extending to the second partial electrode layer is formed on the support substrate, the second partial electrode layer is exposed in the second through hole, metal is deposited in the second through hole and extends out of the support substrate, and the metal deposited in the fourth through hole and extending out of the support substrate is the second conductive pad. The structure of the heat-conducting pad is that a through hole is formed on the support substrate until the heat-conducting layer is exposed, and metal is deposited in the through hole on the support substrate and extends out of the support substrate, and the metal deposited in the through hole on the support substrate and extending out of the support substrate is the heat-conducting pad.

2. The film bulk acoustic resonator with high power capacity of claim 1, wherein, The part of the first heat-conducting pad extending out of the support substrate is connected with the part of the second heat-conducting pad extending out of the support substrate.

3. The film bulk acoustic resonator with high power capacity of claim 1, wherein, The passivation layer covers one end of the second electrode layer, and the passivation layer is connected with the piezoelectric layer, and the other end of the second electrode layer is electrically connected with the second local electrode layer.

4. The film bulk acoustic resonator with high power capacity of claim 1, wherein, An edge of the first electrode layer is provided with a sealing layer, the first electrode layer and the sealing layer are separated from each other, and the sealing layer is located between the heat-conducting layer and the piezoelectric layer.

5. The film bulk acoustic resonator with high power capacity according to any one of claims 1 to 4, characterized in that, The packaging cover plate provided with the second recess is also included, the piezoelectric layer covers the opening of the second recess to form a second cavity, and the fourth metal layer, the passivation layer and the second electrode layer are all located in the second cavity, and the fourth metal layer, the passivation layer and the second electrode layer are all in non-contact with the packaging cover plate, wherein a first through hole extending to the first local electrode layer is formed on the piezoelectric layer, and the fourth metal layer is deposited in the first through hole.

6. The film bulk acoustic resonator with high power capacity according to any one of claims 1 to 4, characterized in that, The material of the heat-conducting layer is diamond.

7. A production method for producing a thin film bulk acoustic resonator having a high power capacity, characterized by, It comprises: A first recess is formed on a support substrate, and a heat-conducting layer is prepared on the surface of the support substrate where the first recess is located, and the heat-conducting layer covers each surface in the first recess; A seed layer and a piezoelectric layer are sequentially prepared on a transfer substrate, a first metal layer is prepared on the piezoelectric layer and is patterned to obtain a first electrode layer, and a sealing layer is prepared at the edge of the first electrode layer, and the first electrode layer and the sealing layer are separated from each other, wherein the first electrode layer comprises a first local electrode layer and a second local electrode layer which are separated from each other; The first local electrode layer covers the opening of the first recess to form a first cavity, and the sealing layer is located between the heat-conducting layer and the piezoelectric layer; The seed layer and the transfer substrate are removed, a second metal layer is prepared on the piezoelectric layer and is patterned to obtain a second electrode layer; A passivation layer is prepared on the second electrode layer, the passivation layer covers one end of the second electrode layer, and the passivation layer is connected with the piezoelectric layer, and the other end of the second electrode layer is electrically connected with the second local electrode layer; The second local electrode layer is electrically connected with the second electrode layer, a first through hole extending to the first local electrode layer is formed on the piezoelectric layer, and a fourth metal layer is deposited in the first through hole, and the fourth metal layer extends out of the piezoelectric layer, and the fourth metal layer is in non-contact with the passivation layer; A packaging cover plate with a second recess is prepared, the piezoelectric layer covers the opening of the second recess to form a second cavity, the fourth metal layer, the passivation layer and the second electrode layer are all located in the second cavity, and the fourth metal layer, the passivation layer and the second electrode layer are all in non-contact with the packaging cover plate; A first conductive pad for connecting the first local electrode layer and the heat-conducting layer is prepared and extends out of the support substrate, a second conductive pad for connecting the second local electrode layer and the heat-conducting layer is prepared and extends out of the support substrate, and a heat-conducting pad for connecting the heat-conducting layer is prepared and extends out of the support substrate; The support substrate is provided with a fifth through hole extending to the first partial electrode layer, and the first conductive pad fills the fifth through hole and extends out of the support substrate; the support substrate is provided with a second through hole extending to the second partial electrode layer, and the second conductive pad fills the second through hole and extends out of the support substrate; The implementation of the electrical connection between the second partial electrode layer and the second electrode layer is as follows: The second partial electrode layer is exposed by etching the piezoelectric layer, and then a third metal layer is deposited to cover one end of the second electrode layer, thereby realizing the electrical connection between the second partial electrode layer and the second electrode layer through the third metal layer; The support substrate is provided with a third through hole and a fourth through hole extending to the heat conduction layer, the first heat conduction pad fills the third through hole and extends out of the support substrate, and the second heat conduction pad fills the fourth through hole and extends out of the support substrate; The structure of the first conductive pad is that a fifth through hole extending to the first partial electrode layer is formed on the support substrate, the first partial electrode layer is exposed in the fifth through hole, metal is deposited in the fifth through hole and extends out of the support substrate, and the metal deposited in the fifth through hole and extending out of the support substrate is the first conductive pad; The structure of the second conductive pad is that a second through hole extending to the second partial electrode layer is formed on the support substrate, the second partial electrode layer is exposed in the second through hole, metal is deposited in the second through hole and extends out of the support substrate, and the metal deposited in the fourth through hole and extending out of the support substrate is the second conductive pad; The structure of the heat conduction pad is that a through hole is formed on the support substrate until the heat conduction layer is exposed, and metal is deposited in the through hole on the support substrate and extends out of the support substrate, and the metal deposited in the through hole on the support substrate and extending out of the support substrate is the heat conduction pad.

8. A film bulk acoustic resonator filter, characterized by, The film bulk acoustic resonator comprises the thin film bulk acoustic resonator according to any one of claims 1 to 6.

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