Bulk acoustic wave resonator and filter
By integrating a capacitor structure inside the bulk acoustic resonator, the problem of filter performance degradation caused by additional wiring and large size in the prior art is solved, achieving the effect of improving filter performance and applicability without increasing the area.
Patent Information
- Application Number
- CN202423152670.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2034-12-19
AI Technical Summary
Existing technologies require additional wiring and larger dimensions when integrating acoustic resonators with capacitors and inductors, which leads to a decrease in filter performance and fails to meet the requirements of high bandwidth and high out-of-band rejection in 5G and WiFi 7 communications.
By integrating the capacitor structure inside the bulk acoustic wave resonator, and forming the capacitor structure between the top electrode and the electrode plate, the electrode plate is supported by the support layer and the dielectric layer, avoiding additional wiring, increasing the area while improving the filter performance.
Without increasing the area, the performance and applicability of the filter were improved, the capacitance value was increased, the resonant frequency was adjusted, and the Q value and reliability of the filter were improved.
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Figure CN223599832U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of communication, in particular to a bulk acoustic wave resonator and a filter. BACKGROUND
[0002] Before 4G communication technology and 4G communication technology, due to the relatively narrow width of the frequency band definition, according to the requirements of the radio frequency system, the electromagnetic or acoustic filter can meet the performance requirements. But after entering the 5G, 6G and WiFi7 stage, the frequency band definition specification has changed significantly, all frequency bands are defined as more than 500MHz of large bandwidth, and the frequency band spacing is gradually narrowed, and the filter that can support large bandwidth and high out-of-band suppression at the same time is required, and the traditional electromagnetic filter and acoustic filter cannot meet the requirements. The hybrid filter composed of acoustic resonator and LC circuit has become a general solution for the next stage of 5G, WiFi7 and other communications.
[0003] The hybrid filter is a device formed by series or parallel connection of an acoustic resonator and an inductor or a capacitor at both ends of the acoustic resonator. The series or parallel connection of the capacitor and the inductor can shift the series resonance frequency or the parallel resonance frequency of the resonator. By reasonably designing the values and connection modes of the IPD elements, the effective electromechanical coupling coefficient and the wideband of the resonator after hybrid design can be increased. In the prior art, the patch connection mode is used when the resonator is integrated with the capacitor and the inductor. Extra wiring is required, and the size of the resonator is larger than that of the resonator, which reduces the performance of the filter and cannot reduce the area, greatly limiting the performance of the filter. Practical new type content
[0004] The purpose of the present application is to provide a bulk acoustic wave resonator and a filter that can improve the performance of the filter without increasing the area.
[0005] An embodiment of the present application provides a bulk acoustic wave resonator, which comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode arranged on the substrate in sequence, and a support layer and an electrode plate arranged on the top electrode in sequence, the electrode plate and the top electrode being oppositely arranged in the layer direction to form a capacitor structure.
[0006] As an implementable mode, the support layer comprises a support ring and a dielectric layer arranged in the enclosed space of the support ring.
[0007] As an implementable mode, the support layer comprises a support ring, and the support ring encloses a cavity.
[0008] As an implementable manner, the top electrode is further provided with a partition wall, the partition wall passes through the support layer and the electrode plate to divide the electrode plate into a first electrode part and a second electrode part, the first electrode part and the corresponding top electrode form a first sub-capacitor, the second electrode part and the corresponding top electrode part form a second sub-capacitor, and the first sub-capacitor and the second sub-capacitor are connected in parallel through the top electrode.
[0009] As an implementable manner, the height of the partition wall in the layer direction is greater than or equal to the height of the electrode plate and the support layer in the layer direction.
[0010] As an implementable manner, the first electrode part and the top electrode are provided with a first dielectric sub-layer, the second electrode part and the top electrode are provided with a second dielectric sub-layer, and the first dielectric sub-layer and the second dielectric sub-layer are of the same material.
[0011] As an implementable manner, the part of the top electrode, the piezoelectric layer and the bottom electrode that is projected and overlapped on the substrate is an effective resonance area, and the support layer is arranged on the effective resonance area.
[0012] As an implementable manner, the bottom electrode and the substrate are further provided with a seed layer.
[0013] As an implementable manner, the upper surface of the substrate and the bottom electrode are further provided with an acoustic reflection structure, and the acoustic reflection structure includes a cavity structure or a stack formed by alternately arranging high and low acoustic impedance materials.
[0014] Another aspect of the embodiments of the present application provides a filter including a plurality of the bulk acoustic wave resonators connected in cascade.
[0015] The beneficial effects of the embodiments of the present application include:
[0016] The bulk acoustic wave resonator provided by the present application includes a substrate, a bottom electrode, a piezoelectric layer and a top electrode arranged on the substrate in sequence, and a support layer and an electrode plate arranged on the top electrode in sequence, and the electrode plate and the top electrode are arranged oppositely in the layer direction to form a capacitor structure. The embodiments of the present application use the top electrode as one plate of the capacitor structure, and the electrode plate is arranged oppositely to the top electrode as the other plate of the capacitor structure, so that the top electrode and the electrode plate are arranged oppositely in the layer direction to form the capacitor structure. That is, the embodiments of the present application integrate the capacitor structure in the bulk acoustic wave resonator, thereby improving the performance of the filter without increasing the area. BRIEF DESCRIPTION OF DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.
[0018] Figure 1 A structural schematic diagram of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0019] Figure 2 A structural schematic diagram of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0020] Figure 3 A structural schematic diagram of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0021] Figure 4 A structural schematic diagram of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0022] Figure 5 A flow chart of a preparation method of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0023] Figure 6 A state diagram of a preparation method of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0024] Figure 7 A state diagram of a preparation method of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0025] Figure 8 A state diagram of a preparation method of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0026] Figure 9 A state diagram of a preparation method of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0027] Figure 10 A state diagram of a preparation method of a bulk acoustic wave resonator provided by an embodiment of the present application;
[0028] Figure 11 A state diagram of a preparation method of a bulk acoustic wave resonator provided by an embodiment of the present application.
[0029] Icon: 100 - bulk acoustic wave resonator; 110 - substrate; 120 - bottom electrode; 130 - piezoelectric layer; 140 - top electrode; 150 - seed layer; 160 - support layer; 161 - support ring; 162 - cavity; 163 - dielectric layer; 170 - electrode plate; 171 - first electrode part; 172 - second electrode part; 180 - isolation wall; 190 - capacitance structure; 191 - first sub-capacitance; 192 - second sub-capacitance; 193 - first dielectric sub-layer; 194 - second dielectric sub-layer; 195 - acoustic reflection structure; 196 - lead-out structure. DETAILED DESCRIPTION
[0030] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some 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 herein can be arranged and designed in various different configurations.
[0031] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts fall within the scope of protection of the present application.
[0032] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.
[0033] The embodiments of the present application provide a bulk acoustic wave resonator 100, as shown in Figure 1 and Figure 2 including a substrate 110 and a bottom electrode 120, a piezoelectric layer 130 and a top electrode 140 arranged on the substrate 110 in sequence, and a support layer 160 and an electrode plate 170 arranged on the top electrode 140 in sequence, the electrode plate 170 and the top electrode 140 are arranged opposite to each other in the layer direction to form a capacitance structure 190.
[0034] The body acoustic wave resonator 100 provided by the embodiment of the present application integrates the capacitor structure 190 in the body acoustic wave resonator 100, fully utilizes the space in the body acoustic wave resonator 100, and does not need additional wiring and patch positions when the filter is formed in cascade in the body acoustic wave resonator 100, thereby improving the performance of the filter without increasing the area. Specifically, the body acoustic wave resonator 100 of the embodiment of the present application includes a substrate 110 and a bottom electrode 120, a piezoelectric layer 130 and a top electrode 140 arranged on the substrate 110 in sequence, wherein the bottom electrode 120, the piezoelectric layer 130 and the top electrode 140 are arranged in sequence along the hierarchical direction to form a sandwich structure, serving as a working unit of the body acoustic wave resonator 100. Specifically, during the working of the sandwich structure, the bottom electrode 120 and the top electrode 140 are respectively connected to two ends of an external signal source, so that the top electrode 140 and the bottom electrode 120 have a voltage difference therebetween, the piezoelectric layer 130 is made of piezoelectric material and generates acoustic waves propagating along the hierarchical direction under the piezoelectric effect due to the voltage difference between the top electrode 140 and the bottom electrode 120, and the acoustic waves can form resonance when the wavelength meets a certain wavelength.
[0035] In order to integrate the capacitor in the body acoustic wave resonator 100, the embodiment of the present application further sequentially arranges a support layer 160 and an electrode plate 170 on the top electrode 140, wherein the electrode plate 170 and the top electrode 140 are oppositely arranged in the hierarchical direction to form the capacitor structure 190, that is, the embodiment of the present application uses the top electrode 140 as one plate of the capacitor structure 190, oppositely arranges the electrode plate 170 on the top electrode 140 as another plate of the capacitor structure 190, and oppositely arranges the top electrode 140 and the electrode plate 170 in the hierarchical direction to form the capacitor structure 190. That is, the embodiment of the present application integrates the capacitor structure 190 in the body acoustic wave resonator 100, thereby improving the performance of the filter without increasing the area.
[0036] It can be understood that the two plates of the capacitor structure 190 are oppositely arranged and insulated from each other, therefore, the support layer 160 insulates the top electrode 140 and the electrode plate 170, and specifically, the material and structure of the support layer 160 are not limited in the embodiment of the present application, as long as the top electrode 140 and the electrode plate 170 have a certain gap and are insulated.
[0037] The bulk acoustic wave resonator 100 provided in the application comprises a substrate 110, a bottom electrode 120, a piezoelectric layer 130 and a top electrode 140 arranged on the substrate 110 in sequence, and a support layer 160 and an electrode plate 170 arranged on the top electrode 140 in sequence, and the electrode plate 170 and the top electrode 140 are oppositely arranged in the layer direction to form a capacitor structure 190. The embodiment of the application uses the top electrode 140 as one plate of the capacitor structure 190, and the electrode plate 170 is oppositely arranged on the top electrode 140 as the other plate of the capacitor structure 190, so that the top electrode 140 and the electrode plate 170 are oppositely arranged in the layer direction to form the capacitor structure 190. That is, the embodiment of the application integrates the capacitor structure 190 in the bulk acoustic wave resonator 100, thereby improving the performance of the filter without increasing the area.
[0038] Optionally, as shown in Figure 1 The support layer 160 comprises a support ring 161 and a dielectric layer 163 arranged in the enclosed space of the support ring 161.
[0039] The dielectric layer 163 and the support ring 161 support the electrode plate 170 in structure, so that there is a certain gap between the electrode plate 170 and the top electrode 140, and in addition, the dielectric layer 163 has a large dielectric constant and good insulation effect on the electrode plate 170 and the top electrode 140.
[0040] The dielectric layer 163 and the support ring 161 support the electrode plate 170, which can improve the stability of the structure of the electrode plate 170 and improve the reliability of the bulk acoustic wave resonator 100.
[0041] Specifically, when the support layer 160 comprises the support ring 161 and the dielectric layer 163, the materials of the support ring 161 and the dielectric layer 163 can be the same or different. Figure 1 The materials of the support ring 161 and the dielectric layer 163 are different.
[0042] In an implementable manner of the embodiment of the application, as shown in Figure 2 The support layer 160 comprises a support ring 161, and the support ring 161 forms a cavity 162.
[0043] The support layer 160 supports the support ring 161, the support ring 161 forms the cavity 162, and the cavity 162 is filled with air, that is, an interface with air is formed on the upper surface of the top electrode 140, and when the bulk acoustic wave resonator 100 works, the sandwich structure forms a sound wave propagating in the layer direction, and due to the difference in acoustic reflectivity, the cavity 162 and the top electrode 140 form a reflection structure on the upper surface of the top electrode 140, which can reflect the sound wave propagating to this place back to the inside of the sandwich structure, thereby avoiding sound wave leakage, thereby improving the Q value of the bulk acoustic wave resonator 100.
[0044] Specifically, when the support layer 160 comprises the support ring 161, and the support ring 161 encloses the cavity 162, during the process of the bulk acoustic wave resonator 100, the cavity 162 can be filled with a sacrificial material to make the surface of the support layer 160 flat, so as to facilitate the preparation of the electrode plate 170, and after the preparation of the electrode plate 170 is completed, the sacrificial material is released to form the cavity 162. If the cavity 162 is formed by releasing the sacrificial layer, the material of the sacrificial layer and the material of the support ring 161 must be different, so that the support ring 161 will not be affected when the sacrificial layer is released.
[0045] Optionally, as shown in Figure 3 and Figure 4 , the top electrode 140 is further provided with the isolation wall 180, the isolation wall 180 passes through the support layer 160 and the electrode plate 170 to divide the electrode plate 170 into the first electrode part 171 and the second electrode part 172, the first electrode part 171 and the top electrode 140 corresponding thereto form the first sub-capacitor 191, the second electrode part 172 and the top electrode 140 corresponding thereto form the second sub-capacitor 192, and the first sub-capacitor 191 and the second sub-capacitor 192 are connected in parallel through the top electrode 140.
[0046] The isolation wall 180 is arranged on the top electrode 140 to divide the electrode plate 170 into the first electrode part 171 and the second electrode part 172, so that the first electrode part 171 and the second electrode part 172 form the first sub-capacitor 191 and the second sub-capacitor 192 with the top electrode 140, respectively. Since the isolation wall 180 is arranged on the top electrode 140, the top electrode 140 as a whole connects the plates of the first sub-capacitor 191 and the second sub-capacitor 192, and realizes the parallel connection of the first sub-capacitor 191 and the second sub-capacitor 192.
[0047] After the top electrode 140 forms the first sub-capacitor 191 and the second sub-capacitor 192, and the first sub-capacitor 191 and the second sub-capacitor 192 are connected in parallel through the top electrode 140, as shown in Figure 3 and Figure 4 , the capacitance value of the capacitor structure 190 integrated in the bulk acoustic wave resonator 100 can be increased, which is different from the capacitance value of one capacitor, so that the capacitor structure 190 has different frequency adjustment effects on the resonator, thereby improving the applicability of the bulk acoustic wave resonator 100.
[0048] It can be understood that the isolation wall 180, as an isolation structure for isolating the first electrode part 171 and the second electrode part 172, should have high insulation.
[0049] In an implementable manner of the embodiment of the present application, the height of the isolation wall 180 in the layer direction is greater than or equal to the height of the electrode plate 170 and the support layer 160 in the layer direction, so that the upper surface of the isolation wall 180 protrudes from the upper surface of the electrode plate 170, improving the isolation effect of the isolation wall 180 on the first electrode part 171 and the second electrode part 172.
[0050] Optionally, as shown in Figure 4 , the first electrode part 171 and the top electrode 140 are provided with a first dielectric sub-layer 193, and the second electrode part 172 and the top electrode 140 are provided with a second dielectric sub-layer 194, and the materials of the first dielectric sub-layer 193 and the second dielectric sub-layer 194 are the same.
[0051] The first dielectric sub-layer 193, the second dielectric sub-layer 194 and the support ring 161 support the first electrode part 171 and the second electrode part 172, which can improve the stability of the structure of the first electrode part 171 and the second electrode part 172, thereby improving the reliability of the bulk acoustic wave resonator 100.
[0052] The first dielectric layer and the second dielectric layer are of the same material, and in the preparation process of the bulk acoustic wave resonator 100, the preparation of the first dielectric sub-layer 193 and the second dielectric sub-layer 194 can be realized by one-time deposition, thereby simplifying the preparation steps.
[0053] It can be understood that air can be arranged between the first electrode part 171 and the top electrode 140 to form the first cavity 162, and air can be arranged between the second electrode part 172 and the top electrode 140 to form the second cavity 162.
[0054] In an implementable manner of the embodiment of the present application, the part of the top electrode 140, the piezoelectric layer 130 and the bottom electrode 120 projected and overlapped on the substrate 110 is an effective resonance area, and the support layer 160 is arranged on the effective resonance area.
[0055] Arranging the support layer 160 above the effective resonance area makes the support layer 160 and the electrode plate 170 located above the effective resonance area, which can improve the flatness of the support layer 160 and the electrode plate 170 on the one hand, and the support layer 160 can reflect the acoustic wave in the sandwich structure, thereby improving the Q value of the bulk acoustic wave resonator 100.
[0056] Optionally, as shown in Figure 1 and Figure 2 , the bottom electrode 120 and the substrate 110 are further provided with a seed layer 150.
[0057] The skilled in the art should know that the thin film quality of the piezoelectric layer 130 is in direct proportion to the performance of the bulk acoustic wave resonator 100 within a certain range, in order to improve the thin film quality of the piezoelectric layer 130, the seed layer 150 is further arranged between the bottom electrode 120 and the substrate 110, the seed layer 150 has a guiding effect on the crystal direction of the piezoelectric layer 130, thereby improving the crystal structure of the piezoelectric layer 130, and further improving the thin film quality of the piezoelectric layer 130, thereby improving the performance of the bulk acoustic wave resonator 100.
[0058] In an implementable manner of the embodiment of the application, as shown in Figure 1 、 Figure 2 、 Figure 3 and Figure 4 , the acoustic reflection structure 195 is further arranged between the upper surface of the substrate 110 and the bottom electrode 120, and the acoustic reflection structure 195 includes a cavity structure or a stack formed by alternately arranging high and low acoustic impedance materials.
[0059] As known from the foregoing, the bulk acoustic wave resonator 100 forms an acoustic wave propagating along the hierarchical direction inside the sandwich structure when working, and the acoustic reflection structure 195 is arranged between the upper surface of the substrate 110 and the bottom electrode 120, and the acoustic reflection structure 195 can reflect the acoustic wave propagating thereto, thereby avoiding acoustic wave leakage and improving the Q value of the bulk acoustic wave resonator 100.
[0060] Specifically, the acoustic reflection structure 195 is a cavity structure or a stack formed by alternately arranging high and low acoustic impedance materials.
[0061] The application further discloses a preparation method of the bulk acoustic wave resonator, and specifically, a preparation method flow chart is as shown in Figure 5 , and the preparation method includes the following steps.
[0062] S10: as shown in Figure 6 , etching a groove on the substrate 110, and arranging a sacrificial material in the groove so that the sacrificial material fills the groove, and depositing the seed layer 150, the bottom electrode 120 and the piezoelectric layer 130 on the upper surface of the substrate 110;
[0063] The material of the substrate 110 includes but is not limited to silicon, silicon carbide, sapphire, gallium arsenide, etc. The material of the bottom electrode 120 includes but is not limited to molybdenum, aluminum, copper and alloys thereof. The material of the piezoelectric layer 130 includes but is not limited to aluminum nitride, scandium-doped aluminum nitride, lithium niobate, lithium tantalate, zinc oxide, etc.
[0064] S20: as shown in Figure 7 , etching the piezoelectric layer 130 to form a lead-out groove, and depositing a metal material on the piezoelectric layer 130 and etching, the metal material filling the lead-out groove being the lead-out structure 196, and the metal material deposited on the piezoelectric layer 130 forming the top electrode 140;
[0065] S30: asFigure 8 As shown, a support ring 161 is formed on the top electrode 140;
[0066] The material of the support layer 160 includes, but is not limited to, dielectric materials such as aluminum oxide, silicon carbide, silicon nitride, zinc oxide, etc.
[0067] Specifically, the support ring 161 can be formed by depositing an entire layer and then etching.
[0068] S40: As shown in FIG. 4, a support layer 160 is formed in the support ring 161; Figure 9
[0069] S50: As shown in FIG. 5, an electrode plate 170 is deposited on the support layer 160; Figure 10
[0070] The material of the electrode plate 170 includes, but is not limited to, aluminum copper molybdenum and its alloys.
[0071] S60: As shown in FIG. 6, the sacrificial material is released to form a cavity 162; Figure 11
[0072] The application further discloses a filter comprising a plurality of the above-mentioned bulk acoustic resonators 100 connected in cascade. The filter has the same structure and advantages as the bulk acoustic resonator 100 in the foregoing embodiments. Specifically, the bulk acoustic resonator 100 of the application integrates the capacitor structure 190 on the top electrode 140, and uses the top electrode 140 as one electrode plate 170 of the capacitor structure 190, so that the performance of the filter can be improved without increasing the area.
[0073] The above only describes the preferred embodiments of the application and is not used to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application shall be included in the protection scope of the application.
Claims
1. A bulk acoustic wave resonator, characterized by, The device comprises a substrate, a bottom electrode, a piezoelectric layer, a top electrode, a support layer and an electrode plate, which are sequentially arranged on the substrate.
2. The bulk acoustic resonator of claim 1, wherein, The support layer comprises a support ring and a dielectric layer arranged in the space enclosed by the support ring.
3. The bulk acoustic resonator of claim 1, wherein, The support layer comprises a support ring, which encloses a cavity.
4. The bulk acoustic resonator of claim 1, wherein, The top electrode further comprises an isolation wall, which divides the electrode plate into a first electrode part and a second electrode part.
5. The bulk acoustic resonator of claim 4, wherein, The height of the isolation wall in the layer direction is greater than or equal to the height of the electrode plate and the support layer in the layer direction.
6. The bulk acoustic resonator of claim 4, wherein, The first electrode part and the top electrode are separated by a first dielectric sub-layer, and the second electrode part and the top electrode are separated by a second dielectric sub-layer.
7. The bulk acoustic resonator of claim 1, wherein, The top electrode, the piezoelectric layer and the bottom electrode overlap in the projection on the substrate, and the support layer is arranged on the overlapping area.
8. The bulk acoustic resonator of claim 1, wherein, The bottom electrode and the substrate further comprise a seed layer.
9. The bulk acoustic resonator of claim 1, wherein, The upper surface of the substrate and the bottom electrode further comprise a sound reflection structure, which comprises a cavity structure or a stack of high and low sound impedance materials.
10. A filter, characterized by, A plurality of bulk acoustic wave resonators according to any one of claims 1-9 are connected in cascade.