Bulk acoustic wave filter
By designing a bulk acoustic wave filter, using the combination of stacked structure and capacitors or inductors to optimize the acoustic wave propagation characteristics, the problem of insufficient performance of existing RF devices under high frequency operating conditions is solved, and higher high-frequency passability and clutter resistance are achieved.
Patent Information
- Application Number
- CN202411653290.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-03-07
Smart Images
Figure CN119582800A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of radio frequency devices, and in particular to a bulk acoustic wave filter. Background Art
[0002] With the continuous advancement of science and technology and the development of the communications industry in recent years, mobile terminals, such as mobile phones, have become more and more popular. In order to achieve the selective passage or blocking of specific frequency signals, filters have become an indispensable RF device in mobile terminals. With the rise of 4G / LTE around 2012 and the launch of 5G in recent years, the mobile data traffic of smartphones has surged and is expected to reach 2B in the next few years. The new standard requires higher data rates, and the RF devices provided by existing technologies cannot meet application requirements under high-frequency conditions. The limitations are too strong, which has become an obstacle to the implementation of the new standard. Summary of the invention
[0003] The purpose of the present application is to provide a bulk acoustic wave filter, which can effectively improve the high-frequency passability of the filter, reduce clutter, and improve the performance of the filter device.
[0004] The embodiment of the present application is implemented as follows:
[0005] An embodiment of the present application provides a bulk acoustic wave filter, comprising a stacked substrate, a bottom electrode, a piezoelectric layer and a top electrode; a terminal structure is connected to the bottom electrode, the terminal structure forms a first projection area on the substrate, the piezoelectric layer forms a second projection area on the substrate, and the first projection area and the second projection area are spaced apart; a capacitor or inductor is arranged between the terminal structure and the bottom electrode, for realizing electrical connection between the terminal structure and the bottom electrode.
[0006] As an optional implementation, the capacitor includes a first capacitor electrode layer, a dielectric layer, and a second capacitor electrode layer stacked on the bottom electrode.
[0007] As an optional implementation manner, the inductor includes a first inductor electrode layer, a comb-shaped inductor layer, and a second inductor electrode layer stacked on the bottom electrode.
[0008] As an optional embodiment, two of the terminal structures are connected to the bottom electrode, and two of the capacitors respectively connected to the two terminal structures are arranged on the bottom electrode; or, two of the inductors respectively connected to the two terminal structures are arranged on the bottom electrode; or, the first terminal structure is connected to the bottom electrode via the capacitor, and the second terminal structure is connected to the bottom electrode via the inductor.
[0009] As an optional implementation manner, the two terminal structures are located on a side of the bottom electrode facing away from the substrate.
[0010] As an optional implementation, the two terminal structures are located on a side of the bottom electrode close to the substrate, and the capacitor or the inductor is embedded in the substrate.
[0011] As an optional implementation, the first terminal structure is used for signal input, and the second terminal structure is used for signal output.
[0012] As an optional implementation, at least two terminal structures for grounding are also included.
[0013] As an optional implementation, the first capacitor electrode layer includes a first molybdenum electrode layer; the second capacitor electrode layer includes a first gold electrode layer; and the dielectric layer includes a silicon dioxide layer.
[0014] As an optional implementation, the first inductor electrode layer includes a second molybdenum electrode layer; the second inductor electrode layer includes a second gold electrode layer; and the comb-shaped inductor layer includes a third molybdenum electrode layer.
[0015] The beneficial effects of the embodiments of the present application include:
[0016] The embodiment of the present application provides a bulk acoustic wave filter, including a stacked substrate, a bottom electrode, a piezoelectric layer, and a top electrode; the bottom electrode of the embodiment of the present application is connected to a terminal structure, the terminal structure forms a first projection area on the substrate, and the piezoelectric layer forms a second projection area on the substrate, and the first projection area and the second projection area are spaced apart. There is a spacing between the terminal structure and the piezoelectric layer of the embodiment of the present application, and a capacitor or inductor is provided between the terminal structure and the bottom electrode for realizing an electrical connection between the terminal structure and the bottom electrode. The bulk acoustic wave filter provided by the embodiment of the present application can effectively improve the high-frequency passability of the filter, reduce clutter, and improve the performance of the filter device. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0018] Figure 1 This is one of the structural schematic diagrams of the bulk acoustic wave filter of the embodiment of the present application;
[0019] Figure 2This is the second structural schematic diagram of the bulk acoustic wave filter of the embodiment of the present application;
[0020] Figure 3 This is the third structural schematic diagram of the bulk acoustic wave filter of the embodiment of the present application;
[0021] Figure 4 This is the fourth structural diagram of the bulk acoustic wave filter of the embodiment of the present application;
[0022] Figure 5 This is the fifth structural diagram of the bulk acoustic wave filter of the embodiment of the present application;
[0023] Figure 6 This is the sixth structural schematic diagram of the bulk acoustic wave filter according to the embodiment of the present application.
[0024] Icon: 100-substrate; 101-bottom electrode; 102-piezoelectric layer; 103-top electrode; 104-terminal structure; 105-first projection area; 106-second projection area; 107-capacitor; 108-inductor; 109-first capacitor electrode layer; 110-dielectric layer; 111-second capacitor electrode layer; 112-first inductor electrode layer; 113-comb inductor layer; 114-second inductor electrode layer. DETAILED DESCRIPTION
[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.
[0026] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.
[0027] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0028] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0029] With the continuous advancement of science and technology and the development of the communications industry in recent years, mobile terminals, such as mobile phones, have become more and more popular. In order to achieve the selective passage or blocking of specific frequency signals, filters have become an indispensable RF device in mobile terminals. With the rise of 4G / LTE around 2012 and the launch of 5G in recent years, the mobile data traffic of smartphones has surged and is expected to reach 2B in the next few years. The new standard requires higher data rates, and the RF devices provided by existing technologies cannot meet application requirements under high-frequency conditions. The limitations are too strong, which has become an obstacle to the implementation of the new standard.
[0030] In order to solve the above technical problems, an embodiment of the present application provides a bulk acoustic wave filter.
[0031] Reference Figure 1 , Figure 2 as well as Figure 3 As shown, an embodiment of the present application provides a bulk acoustic wave filter, including a stacked substrate 100, a bottom electrode 101, a piezoelectric layer 102 and a top electrode 103; a terminal structure 104 is connected to the bottom electrode 101, the terminal structure 104 forms a first projection area 105 on the substrate 100, and the piezoelectric layer 102 forms a second projection area 106 on the substrate 100, and the first projection area 105 and the second projection area 106 are spaced apart; a capacitor 107 or an inductor 108 is arranged between the terminal structure 104 and the bottom electrode 101, for realizing electrical connection between the terminal structure 104 and the bottom electrode 101.
[0032] It should be noted that the BAW filter provided in the embodiment of the present application includes a substrate 100 , a bottom electrode 101 , a piezoelectric layer 102 and a top electrode 103 which are stacked.
[0033] The bottom electrode 101, the piezoelectric layer 102 and the top electrode 103 form a sandwich structure on the substrate 100. The sandwich structure improves the performance of the resonator by optimizing the propagation and reflection characteristics of the sound wave.
[0034] The piezoelectric layer 102 may be made of piezoelectric materials such as aluminum nitride and lead zirconate titanate. The piezoelectric material may generate mechanical vibrations under the action of electrical signals to form sound waves. The substrate 100 may be composed of multiple layers of alternating high and low refractive index materials, such as silicon dioxide and silicon nitride. The substrate 100 may reflect sound waves, reduce energy loss, and enhance resonance effects.
[0035] Reference Figure 1 , Figure 2 as well as Figure 3 As shown, a terminal structure 104 is connected to the bottom electrode 101 of the embodiment of the present application, the terminal structure 104 forms a first projection area 105 on the substrate 100, and the piezoelectric layer 102 forms a second projection area 106 on the substrate 100, and there is a spacing between the first projection area 105 and the second projection area 106. There is a spacing between the terminal structure 104 and the piezoelectric layer 102 of the embodiment of the present application, and a capacitor 107 or an inductor 108 is provided between the terminal structure 104 and the bottom electrode 101, for realizing electrical connection between the terminal structure 104 and the bottom electrode 101.
[0036] It should be noted that the sandwich structure resonator has high linearity and is suitable for high-power RF applications.
[0037] The embodiment of the present application sets a capacitor 107 at the terminal structure 104 of the sandwich-structured resonator, which can optimize the frequency tuning, impedance matching, bandwidth control and filtering characteristics of the resonator, ensure that the filter has high selectivity within a specific frequency range, and significantly improve the performance of the resonator.
[0038] Regarding frequency tuning, capacitor 107 can change the effective capacitance 107 of the resonator, thereby adjusting the resonant frequency. Capacitor 107 works together with the parasitic capacitance 107 of the resonator to change the total capacitance 107 of the resonator, thereby affecting the resonant frequency. By selecting the appropriate value of capacitor 107, the resonant frequency can be adjusted to the desired operating frequency.
[0039] The capacitor 107 can be used to achieve impedance matching. By adjusting the value of the capacitor 107, the input and output impedances of the resonator can be changed to match the impedance of the external circuit, which helps to improve signal transmission efficiency and reduce reflections, ensuring that reflections and mismatches are minimized during signal transmission.
[0040] Regarding bandwidth control, the series capacitor 107 can affect the bandwidth of the resonator, and the frequency response characteristics of the resonator can be controlled by adjusting the value of the capacitor 107. The principle is that the introduction of the series capacitor 107 will change the equivalent circuit model of the resonator, thereby affecting its quality factor Q value and bandwidth. A smaller capacitor 107 value will increase the bandwidth, and a larger capacitor 107 value will reduce the bandwidth.
[0041] Regarding the description of filtering characteristics, the series capacitor 107 can be used to improve the filtering characteristics of the resonator and increase the frequency selectivity. By properly selecting the value of the series capacitor 107, the selectivity of the resonator within a specific frequency range can be enhanced, and unnecessary frequency components can be filtered out.
[0042] It should be noted that the arrangement of the inductor 108 at the terminal structure 104 of the sandwich structure resonator can not only optimize the frequency tuning, impedance matching, bandwidth control and filtering characteristics of the resonator, but also significantly improve the performance of the resonator by properly selecting the value of the inductor 108, making it better adapted to various application requirements.
[0043] In addition, the inductor 108 can also improve the stability of the resonator, reduce the influence of external interference, and improve the anti-interference ability of the circuit.
[0044] Specifically, the inductor 108 can provide additional energy storage and filtering functions, and reduce the impact of high-frequency noise and transient interference on the resonator.
[0045] Therefore, the BAW filter provided in the embodiment of the present application can effectively improve the high-frequency passability of the filter, reduce clutter, and improve the performance of the filter device.
[0046] Reference Figure 3 as well as Figure 5 As shown, as an optional implementation, the capacitor 107 includes a first capacitor electrode layer 109 , a dielectric layer 110 , and a second capacitor electrode layer 111 stacked on the bottom electrode 101 .
[0047] The first capacitor electrode layer 109 includes a first molybdenum electrode layer; the second capacitor electrode layer 111 includes a first gold electrode layer; and the dielectric layer 110 includes a silicon dioxide layer.
[0048] Reference Figure 4 as well as Figure 6 As shown, as an optional implementation, the inductor 108 includes a first inductor electrode layer 112 , a comb-shaped inductor layer 113 , and a second inductor electrode layer 114 stacked on the bottom electrode 101 .
[0049] The first inductor electrode layer 112 includes a second molybdenum electrode layer; the second inductor electrode layer 114 includes a second gold electrode layer; and the comb-shaped inductor layer 113 includes a third molybdenum electrode layer.
[0050] As an optional implementation, refer to Figure 2As shown, two terminal structures 104 are connected to the bottom electrode 101, and two capacitors 107 respectively connected to the two terminal structures 104 are arranged on the bottom electrode 101; or, two inductors 108 respectively connected to the two terminal structures 104 are arranged on the bottom electrode 101; or, the first terminal structure 104 is connected to the bottom electrode 101 through the capacitor 107, and the second terminal structure 104 is connected to the bottom electrode 101 through the inductor 108.
[0051] Exemplarily, two terminal structures 104 are connected to the bottom electrode 101 , the first terminal structure 104 is used for signal input, and the second terminal structure 104 is used for signal output. Two capacitors 107 connected to the two terminal structures 104 are disposed on the bottom electrode 101 .
[0052] Exemplarily, two terminal structures 104 are connected to the bottom electrode 101 , the first terminal structure 104 is used for signal input, and the second terminal structure 104 is used for signal output. Two inductors 108 connected to the two terminal structures 104 are disposed on the bottom electrode 101 .
[0053] Exemplarily, two terminal structures 104 are connected to the bottom electrode 101, the first terminal structure 104 is used for signal input, and the second terminal structure 104 is used for signal output. The first terminal structure 104 is connected to the bottom electrode 101 through a capacitor 107, and the second terminal structure 104 is connected to the bottom electrode 101 through an inductor 108.
[0054] Exemplarily, two terminal structures 104 are connected to the bottom electrode 101, the first terminal structure 104 is used for signal input, and the second terminal structure 104 is used for signal output. The second terminal structure 104 is connected to the bottom electrode 101 through a capacitor 107, and the first terminal structure 104 is connected to the bottom electrode 101 through an inductor 108.
[0055] It should be noted that the number of the terminal structures 104 can be set by those skilled in the art as required, and there is no special limitation on this.
[0056] As an optional implementation, the two terminal structures 104 are located on the side of the bottom electrode 101 facing away from the substrate 100 .
[0057] It should be noted that the terminal structure 104 is located on the side of the bottom electrode 101 away from the substrate 100, and the terminal structure 104 is a solder ball bump. The solder ball bump is arranged on the second capacitor electrode layer 111 or the second inductor electrode layer 114, wherein the second capacitor electrode layer 111 and the second inductor electrode layer 114 are both electrode layers made of gold.
[0058] Different from the above embodiment, the two terminal structures 104 may also be located on the side of the bottom electrode 101 close to the substrate 100 , and the capacitor 107 or the inductor 108 may be embedded in the substrate 100 .
[0059] It should be noted that the terminal structure 104 may also be located on the side of the bottom electrode 101 close to the substrate 100. When the capacitor 107 is provided between the terminal structure 104 and the bottom electrode 101, the first capacitor electrode layer 109, the second capacitor electrode layer 111, and the dielectric layer 110 are pre-buried in the substrate 100. The capacitor 107 can be protected by the substrate 100.
[0060] Similarly, when the inductor 108 is arranged between the terminal structure 104 and the bottom electrode 101, the first inductor electrode layer 112, the comb-shaped inductor layer 113 and the second inductor electrode layer 114 are pre-buried in the substrate 100. The inductor 108 can be protected by the substrate 100. Those skilled in the art can set the above arrangement as needed.
[0061] As an optional implementation, at least two terminal structures 104 for grounding are also included.
[0062] Furthermore, the embodiment of the present application also includes at least two terminal structures 104 for grounding.
[0063] Exemplarily, the embodiment of the present application has four terminal structures 104, two of which are located on the side of the bottom electrode 101 away from the substrate 100, the first terminal structure 104 is used for signal input, and the second terminal structure 104 is used for signal output. Two capacitors 107 are respectively connected to the two terminal structures 104 on the bottom electrode 101. The other two terminal structures 104 are also located on the side of the bottom electrode 101 close to the substrate 100. These two terminal structures 104 are used for grounding, and two inductors 108 are respectively connected to the two terminal structures 104 on this side.
[0064] Exemplarily, the embodiment of the present application has four terminal structures 104, two of which are located on the side of the bottom electrode 101 away from the substrate 100, the first terminal structure 104 is used for signal input, and the second terminal structure 104 is used for signal output. Two inductors 108 are respectively connected to the two terminal structures 104 on the bottom electrode 101. The other two terminal structures 104 are also located on the side of the bottom electrode 101 close to the substrate 100. These two terminal structures 104 are used for grounding, and two capacitors 107 are respectively connected to the two terminal structures 104 on this side.
[0065] Exemplarily, the embodiment of the present application has six terminal structures 104, two of which are located on the side of the bottom electrode 101 away from the substrate 100, the first terminal structure 104 is used for signal input, and the second terminal structure 104 is used for signal output. Two capacitors 107 are provided on the bottom electrode 101 and are respectively connected to the two terminal structures 104. The other four terminal structures 104 are also located on the side of the bottom electrode 101 close to the substrate 100, and these two terminal structures 104 are used for grounding. Four inductors 108 are provided on the bottom electrode 101 on this side and are respectively connected to the four terminal structures 104.
[0066] It should be noted that the above-mentioned terminal structure 104 can be a metal pad or a solder ball bump, and those skilled in the art can configure it as required.
[0067] In addition, it should be noted that the capacitor 107 and the inductor 108 of the embodiment of the present application are arranged at the edge area of the BAW filter. In other words, the capacitor 107 and the inductor 108 are spaced apart from the geometric center of the BAW filter, and the spacing is as large as possible. The above arrangement facilitates line connection of the input, output and ground ports.
[0068] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A bulk acoustic wave filter, characterized in that: The invention comprises a stacked substrate (100), a bottom electrode (101), a piezoelectric layer (102) and a top electrode (103); the bottom electrode (101) is connected to a terminal structure (104), the terminal structure (104) forms a first projection area (105) on the substrate (100), the piezoelectric layer (102) forms a second projection area (106) on the substrate (100), and the first projection area (105) and the second projection area (106) are spaced apart; a capacitor (107) or an inductor (108) is arranged between the terminal structure (104) and the bottom electrode (101) to realize electrical connection between the terminal structure (104) and the bottom electrode (101).
2. The bulk acoustic wave filter according to claim 1, characterized in that The capacitor (107) comprises a first capacitor electrode layer (109), a dielectric layer (110) and a second capacitor electrode layer (111) which are stacked on the bottom electrode (101).
3. The bulk acoustic wave filter according to claim 1, wherein: The inductor (108) comprises a first inductor electrode layer (112), a comb-shaped inductor layer (113) and a second inductor electrode layer (114) which are stacked on the bottom electrode (101).
4. The bulk acoustic wave filter according to claim 1, wherein: The bottom electrode (101) is connected to two terminal structures (104), and the bottom electrode (101) is provided with two capacitors (107) respectively connected to the two terminal structures (104); or, the bottom electrode (101) is provided with two inductors (108) respectively connected to the two terminal structures (104); or, the first terminal structure (104) is connected to the bottom electrode (101) via the capacitor (107), and the second terminal structure (104) is connected to the bottom electrode (101) via the inductor (108).
5. The bulk acoustic wave filter according to claim 4, characterized in that The two terminal structures (104) are located on the side of the bottom electrode (101) facing away from the substrate (100).
6. The bulk acoustic wave filter according to claim 4, characterized in that The two terminal structures (104) are located on a side of the bottom electrode (101) close to the substrate (100), and the capacitor (107) or the inductor (108) is embedded in the substrate (100).
7. The bulk acoustic wave filter according to any one of claims 4 to 6, characterized in that: The first terminal structure (104) is used for signal input, and the second terminal structure (104) is used for signal output.
8. The bulk acoustic wave filter according to claim 7, characterized in that Also included are at least two terminal structures (104) for grounding.
9. The bulk acoustic wave filter according to claim 2, characterized in that The first capacitor electrode layer (109) includes a first molybdenum electrode layer; the second capacitor electrode layer (111) includes a first gold electrode layer; and the dielectric layer (110) includes a silicon dioxide layer.
10. The bulk acoustic wave filter according to claim 3, characterized in that The first inductor electrode layer (112) includes a second molybdenum electrode layer; the second inductor electrode layer (114) includes a second gold electrode layer; and the comb-shaped inductor layer (113) includes a third molybdenum electrode layer.