Acoustic resonator, method of manufacturing the same, filter, and electronic device

Abstract

The application provides an acoustic resonator, comprising a substrate, a resonant functional layer arranged above the substrate, the resonant functional layer comprising at least a bottom electrode, a piezoelectric layer and a top electrode arranged in a stack, a resonant cavity arranged between the resonant functional layer and the substrate, an effective resonant area being defined by the area where the resonant functional layer overlaps the resonant cavity, a release hole at least penetrating the piezoelectric layer and communicating with the resonant cavity, a channel penetrating the resonant functional layer and communicating with the resonant cavity, the channel communicating with the release hole through the resonant cavity, and in a horizontal direction, the maximum cross-sectional area of the channel is greater than the maximum cross-sectional area of the release hole. By arranging the channel penetrating the resonant functional layer and communicating with the resonant cavity, the heat center area of the resonator is removed, the heat accumulation of the effective resonant area is reduced, and the temperature uniformity is improved. Further, the side wall of the channel is provided with a reinforcing structure extending along the side edge of any layer in the resonant functional layer to the side edge of another layer, so that the structural strength of the resonator is improved and the transverse wave is inhibited.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to an acoustic resonator and its manufacturing method, a filter, and an electronic device. Background Technology

[0002] The basic structure of a bulk acoustic wave (BAW) resonator is a "sandwich" structure consisting of a bottom electrode, a piezoelectric layer, and a top electrode. When a high-frequency electrical signal is applied between the top and bottom electrodes, due to the inverse piezoelectric effect of the piezoelectric layer, a bulk acoustic wave (BAW) propagating along the thickness direction of the piezoelectric layer is excited within the layer. The propagation path length of the BAW is the sum of the thicknesses of the top and bottom electrodes and the piezoelectric layer. When a certain relationship is satisfied between the BAW wavelength and the propagation path length, standing wave oscillations occur. At this point, the signal resonates within the material, and the equivalent impedance of the device exhibits an extreme value. To optimize the performance of BAW at high frequencies (above 1 GHz), the optimal solution is to miniaturize the "sandwich" structure from a bulk structure into a thin-film structure.

[0003] Currently, bulk acoustic resonators can be categorized into solid-mounted resonators (SMRs) using a Bragg reflector layer and back-etching and air-gap resonators using air as the reflector medium. Strictly speaking, back-etching and air-gap resonators using air as the reflector medium are called thin-film bulk acoustic resonators (FBARs), while resonators using a Bragg reflector layer are often referred to as BAW-SMRs.

[0004] As a radio frequency (RF) device, the FBAR requires an RF voltage applied to two electrodes to act as a power source. Under the action of the RF voltage, the piezoelectric layer generates an alternating electric field. Due to the inverse piezoelectric effect, the piezoelectric layer deforms, which manifests as phonon vibration on a microscopic scale and forms sound waves on a macroscopic scale. These sound waves are bulk acoustic waves inside the piezoelectric body. Through this process, electrical energy is converted into mechanical energy. The bulk acoustic waves reflect back and forth between the top and bottom electrodes. According to the conditions for standing wave formation, standing wave oscillations will occur when the propagation distance of the sound wave is half a wavelength or an odd multiple of half a wavelength. Due to the direct piezoelectric effect, the oscillating bulk acoustic waves will excite the RF electrical signal, completing the conversion of mechanical energy into electrical energy again and forming the resonance of the electrical signal.

[0005] Based on the relationship between the polarization direction and the propagation direction of the bulk acoustic wave, the vibration modes of FBAR can be divided into longitudinal modes and transverse modes. The longitudinal mode is the main resonance. In this mode, the longitudinal wave moves periodically in opposite directions between the electrodes, exhibiting the same phase at all positions of the electrodes. The longitudinal wave propagates along the Z-axis of the FBAR piezoelectric layer. By setting a cavity structure between the substrate and the bottom electrode, the longitudinal wave is reflected back to the resonant region at the interface between the bottom electrode and the air, thus avoiding the loss of acoustic wave energy. The transverse mode is a parasitic mode. The resonator generates transverse waves while generating longitudinal waves. The oscillation of the transverse waves causes energy leakage at the boundary of the effective region of the resonator, resulting in energy loss and thus adversely affecting the Q value.

[0006] Furthermore, the ever-increasing power demands can adversely affect the performance and reliability of resonators. For example, when a higher power radio frequency (RF) signal is applied to a known RF resonator, significant heat generation occurs near the center of the resonant functional layer. Simultaneously, existing resonators primarily dissipate heat to the substrate through the resonant functional layer—the bottom electrode, piezoelectric layer, and top electrode—which has the longest heat dissipation path at its center. Consequently, the thermal resistance near the center of the resonant functional layer is greater when heat is dissipated through the substrate. This heat accumulation near the center of the resonant functional layer can cause damage to the resonator's microstructures due to stress, deformation, and high-temperature burning, leading to device failure, performance degradation, or a reduced actual operating life. Summary of the Invention

[0007] To alleviate or solve at least one of the above-mentioned problems, a first aspect of the present invention provides an acoustic resonator comprising:

[0008] Substrate; resonant functional layer disposed above the substrate, the resonant functional layer comprising at least a bottom electrode, a piezoelectric layer and a top electrode stacked together; resonant cavity disposed between the resonant functional layer and the substrate, the overlapping area of ​​the resonant functional layer and the resonant cavity defined as the effective resonant region; release hole penetrating at least through the piezoelectric layer and communicating with the resonant cavity; channel penetrating the resonant functional layer and communicating with the resonant cavity, the channel communicating with the release hole through the resonant cavity; in the horizontal direction, the maximum cross-sectional area of ​​the channel is greater than the maximum cross-sectional area of ​​the release hole.

[0009] In this design, a channel penetrating the resonant functional layer and communicating with the resonant cavity is provided, allowing the gas inside and outside the resonant cavity to circulate through the channel and the release hole. Under the influence of the temperature difference, the gas inside and outside the resonant cavity spontaneously circulates through the channel and the release hole, further cooling the effective resonant region. At the same time, it also helps to improve the temperature uniformity between different locations in the effective resonant region.

[0010] Furthermore, the resonant functional layer is arranged around the channel. This arrangement positions the channel within the non-edge region of the resonator, resulting in a ring-shaped effective resonant region and a shorter longest heat dissipation path. Additionally, the center of gravity of the effective resonant region is located within the channel.

[0011] Furthermore, the channel is positioned corresponding to the center of the resonant cavity. Typically, the central region of the resonant cavity is where heat accumulates most severely. By removing the resonant functional layer in this region to form the channel, the heat accumulation in the resonator can be effectively reduced.

[0012] Unlike the release holes in existing resonators, the channel proposed in this invention has a larger cross-sectional area, which can remove the heat-generating center region in the resonator. This heat-generating center region is caused by the obstruction of heat transmission. After removing the heat-generating center region in the resonator, an effective ring-shaped resonant region is formed, which can reduce the heat accumulation in the effective resonant region and improve the temperature uniformity between different positions in the effective resonant region.

[0013] Furthermore, the release hole is located on the outer side of the outer edge of the effective resonant region.

[0014] Preferably, the sidewalls of the channel are provided with a reinforcing structure, which extends at least along the side edge of any one of the resonant functional layers to the side edge of another layer in the same resonant functional layer. The acoustic impedance mismatch between the reinforcing structure and the resonant functional layer can suppress transverse waves, effectively reduce energy loss, and improve the Q value; at the same time, the reinforcing structure that fits into the inner edge of the resonant functional layer can provide effective support for the suspended resonant functional layer and strengthen its structural strength.

[0015] Furthermore, the reinforcing structure extends towards the substrate. Compared to extending upwards, reinforcing structures extending towards the substrate are easier to fabricate.

[0016] Furthermore, the reinforcing structure extends at least to the side of the bottom electrode. This reinforcing structure provides more effective support for the suspended resonant functional layer, further strengthening its structural strength. Simultaneously, due to the acoustic impedance mismatch between the bottom electrode near the channel edge and the extended reinforcing structure, energy loss can be effectively reduced, improving the Q value.

[0017] Furthermore, the reinforcing structure is integrally formed with the top electrode and extends at least to the side of the bottom electrode in the direction of the substrate; an insulating groove is provided between the top electrode and the reinforcing structure to achieve electrical insulation between the top electrode and the reinforcing structure and to avoid short circuit between the top electrode and the bottom electrode.

[0018] Furthermore, the reinforcing structure is integrally formed with the piezoelectric layer and extends at least to the bottom electrode side in the direction of the substrate.

[0019] Furthermore, the resonant functional layer also includes a passivation layer disposed above the top electrode, and the reinforcing structure is integrally formed with the passivation layer and extends at least to the side of the bottom electrode in the direction of the substrate.

[0020] Preferably, the lowest point of the reinforcing structure is below the lower surface of the bottom electrode, and a gap is provided between it and the bottom of the resonant cavity. In this case, further downward extension and / or bending of the reinforcing structure can further enhance structural strength and reduce energy loss.

[0021] Furthermore, the ends of the reinforced structure are bent horizontally. The bent ends can increase the structural strength.

[0022] Preferably, the edge of the channel is not parallel to the outer edge of the effective resonant region; in this case, the shortest distance between the edge of the channel and the corresponding outer edge of the effective resonant region is different at different positions, which can effectively increase the length of the transverse wave reflection path, thereby reducing energy loss and improving the Q value.

[0023] Furthermore, the horizontal cross-sectional shape of the channel is circular, elliptical, or polygonal.

[0024] Furthermore, the edge of the channel has the same shape as the outer edge of the effective resonant region.

[0025] Furthermore, the resonant cavity is positioned above or inside the substrate to form an above-ground or underground resonant cavity.

[0026] Furthermore, the resonant cavity is filled with helium. Filling with helium can improve heat dissipation performance.

[0027] A second aspect of this invention provides a method for manufacturing an acoustic resonator, comprising the following steps:

[0028] Provide a substrate, and form a sacrificial layer within or on the substrate;

[0029] A resonant functional layer is provided, which is formed above a sacrificial layer and a substrate. The resonant functional layer includes at least a bottom electrode, a piezoelectric layer and a top electrode stacked together. A channel is formed through the resonant functional layer during the formation of the resonant functional layer.

[0030] A release hole is formed that communicates with the sacrificial layer. The release sacrificial layer forms a resonant cavity, which is connected to the channel. The release hole is connected to the channel through the resonant cavity. The region where the resonant functional layer overlaps with the resonant cavity is defined as the effective resonant region.

[0031] The above manufacturing method forms the aforementioned acoustic resonator with a channel; in the above process, the channel can function simultaneously with the release hole to quickly and completely remove the sacrificial material, reducing damage to the substrate or other structures adjacent to the resonant cavity.

[0032] Furthermore, the minimum distance between the channel edge and the outer edge of the resonant functional layer is greater than zero, causing the resonant functional layer to surround the channel.

[0033] Furthermore, it also includes forming a reinforcing structure on the sidewall of the channel, the reinforcing structure extending at least along the side of any one of the resonant functional layers to the side of another layer in the resonant functional layer.

[0034] Furthermore, it also includes the step of encapsulating the resonator, and filling the encapsulation with helium gas during the encapsulation of the resonator.

[0035] A third aspect of the present invention provides a filter comprising any of the aforementioned acoustic resonators.

[0036] A fourth aspect of the present invention provides an electronic device comprising any of the acoustic resonators described above.

[0037] This invention proposes a resonator with a channel, eliminating the heat-generating center region caused by obstructed heat transfer in conventional resonators, forming a ring-shaped effective resonant region, which reduces heat accumulation in the effective resonant region. Utilizing the channel and release hole connected to the resonant cavity, air cooling is achieved in the effective resonant region under the influence of temperature difference, and the temperature uniformity between different locations within the effective resonant region is improved. Simultaneously, a reinforcing structure is incorporated to create acoustic impedance mismatch, reducing energy loss and improving the Q value. Furthermore, the resonator with the channel can utilize the non-constant distance between the channel edge and the outer edge of the effective resonant region to extend the path length of transverse wave reflection, further reducing energy loss and improving the Q value. Moreover, a reinforcing structure is formed on the sidewall of the channel, which supports the suspended resonant functional layer, enhancing structural strength. Additionally, during packaging, helium gas can be filled inside the package to further improve heat dissipation performance. Attached Figure Description

[0038] The accompanying drawings are provided to further understand this application. For ease of description, only the parts relevant to the invention are shown in the drawings.

[0039] Figure 1 This is a top view schematic diagram of an acoustic resonator in one embodiment of the present invention;

[0040] Figure 2 for Figure 1 The diagram shows a cross-section of the resonator AA.

[0041] Figure 3 This is a top view schematic diagram of an acoustic resonator in another embodiment of the present invention;

[0042] Figure 4 for Figure 3 The diagram shows a schematic of the BB cross-section of the resonator.

[0043] Figure 5This is a top view schematic diagram of an acoustic resonator in another embodiment of the present invention;

[0044] Figure 6 for Figure 5 The diagram shows a schematic of the CC section of the resonator.

[0045] Figure 7 This is a cross-sectional schematic diagram of an acoustic resonator in another embodiment of the present invention;

[0046] Figure 8 This is a cross-sectional schematic diagram of an acoustic resonator in another embodiment of the present invention;

[0047] Figure 9 This is a top view schematic diagram of an acoustic resonator in another embodiment of the present invention;

[0048] Figure 10 for Figure 9 The diagram shows the DD cross-section of the resonator.

[0049] Figures 11a-11g This is a schematic diagram of the manufacturing process of an acoustic resonator in another embodiment of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0051] Because the components of the embodiments can be positioned in several different orientations, the orientations in the reference figures use directional terms such as "top," "bottom," "left," "right," "up," "down," etc., to describe some embodiments. It is understood that the use of directional terms for illustrative purposes is by no means limiting. Other embodiments may be utilized or logical changes may be made without departing from the scope of the invention.

[0052] Figure 1 This is a top view of an acoustic resonator 100 according to an embodiment of the present invention. Figure 2 for Figure 1 A schematic diagram of the AA section of the resonator 100 shown. See also... Figure 1 and Figure 2The resonator 100 includes a substrate 101; a resonant functional layer disposed above the substrate 101, the resonant functional layer including at least a bottom electrode 102, a piezoelectric layer 103 and a top electrode 104 stacked together, the bottom electrode 102 and the top electrode 104 respectively including a bottom electrode connection portion 1021 and a top electrode connection portion 1041 electrically connected to external electronic components; a resonant cavity 105 disposed between the resonant functional layer and the substrate 101, the overlapping area of ​​the resonant functional layer and the resonant cavity 105 being defined as the effective resonant region; a release hole 107 penetrating the piezoelectric layer 103 and communicating with the resonant cavity 105; and a channel 106 penetrating the resonant functional layer and communicating with the resonant cavity 105, and communicating with the release hole 107 through the resonant cavity 105, wherein in the horizontal direction, the maximum cross-sectional area of ​​the channel 106 is greater than the maximum cross-sectional area of ​​the release hole 107.

[0053] In other embodiments, the resonant functional layer is disposed around the channel such that the minimum distance between the edge of the channel and the outer edge of the resonant functional layer is greater than zero. See also... Figure 1 The resonant functional layer of resonator 100 is configured to surround channel 106, in which case the effective resonant region is ring-shaped. See also Figure 2 The circulating gas path shown allows the gas inside and outside the resonant cavity 105 to circulate through the channel 106 and the release hole 107. Compared to resonators in the prior art, the technical effects achieved by the aforementioned channel 106 include: First, the area inside the channel 106 is a non-effective resonant region. The maximum heat dissipation path length at different locations within the annular effective resonant region is shorter than the maximum heat dissipation path length in a conventional effective resonant region of the same area, thereby reducing the maximum thermal resistance within the annular effective resonant region and helping to reduce heat accumulation. Second, with the reduction in maximum thermal resistance, the maximum thermal resistance difference at different locations within the annular effective resonant region also decreases, thereby improving the temperature uniformity between different locations within the effective resonant region. Third, the gas inside the resonant cavity 105 simultaneously receives heat from the substrate 101 and the effective resonant region, and its temperature differs from that of the gas outside the resonant cavity. Under the influence of the temperature difference, the gas inside and outside the resonant cavity 105 spontaneously circulates within and outside the resonant cavity 105 in a self-driven manner through the channel 106 and the release hole 107, further cooling the effective resonant region on the one hand, and also helping to improve the temperature uniformity between different locations within the effective resonant region on the other hand.

[0054] In another specific embodiment, reference can be made to Figure 1 Channel 106 is positioned at a location corresponding to the center of resonant cavity 105. Heat transfer is obstructed in the central region of the resonant cavity; positioning the channel at this center can effectively reduce heat accumulation in the resonator.

[0055] In another specific embodiment, reference can be made to Figure 1The release hole 107 is located on the outer side of the outer edge of the effective resonance region.

[0056] Figure 3 This is a top view of the acoustic resonator 200 in another embodiment of the present invention. Figure 4 for Figure 3 The schematic diagram shows a BB cross-section of the resonator 200. The resonator 200 includes a substrate 201, a bottom electrode 202, a bottom electrode connection portion 2021, a piezoelectric layer 203, a top electrode 204, a top electrode connection portion 2041, a resonant cavity 205, a channel 206, and a release hole 207. Figure 1 , 2 One difference in the illustrated embodiment is that, in this embodiment, the sidewall of channel 206 is provided with a reinforcing structure 2032. The reinforcing structure 2032 is integrally formed with the piezoelectric layer 203 and extends downward along the side of the piezoelectric layer 203 to the bottom electrode 202, constituting part of the sidewall of channel 206. The acoustic impedance mismatch between the reinforcing structure 2032 and the resonant functional layer it covers can suppress transverse waves, effectively reduce energy loss, and improve the Q value; at the same time, the reinforcing structure 2032 can provide effective support for the suspended resonant functional layer, strengthening the structural strength. It can be understood that in other embodiments, the reinforcing structure may extend at least along the side of any one layer of the resonant functional layer to the side of another layer, or it may be formed by multiple extensions within the resonant functional layer.

[0057] In a specific embodiment, to reduce the complexity of the process, the structure is reinforced to extend towards the substrate.

[0058] It is understood that in other embodiments, the reinforcing structure extends at least along the side of any one of the resonant functional layers to the side of another layer in the resonant functional layer. In a preferred embodiment, the end of the reinforcing structure 2032 of the resonator 200 is configured to extend to the side of the bottom electrode 202 and be flush with the bottom of the bottom electrode 202.

[0059] Figure 5 This is a top view of the acoustic resonator 300 in another embodiment of the present invention. Figure 6 for Figure 5The schematic diagram of the CC cross-section of the resonator shown illustrates that the resonator 300 includes a substrate 301, a bottom electrode 302, a bottom electrode connection portion 3021, a piezoelectric layer 303, a top electrode 304, a top electrode connection portion 3041, a resonant cavity 305, a channel 306, and a release hole 307. One difference from the resonator 200 is that, in this embodiment, the reinforcing structure 3042 on the sidewall of the channel 306 is integrally formed with the top electrode 304 and extends towards the substrate 301 to the side of the bottom electrode 302, ultimately becoming flush with the bottom plane of the bottom electrode 302. In this case, the piezoelectric layer 303 and the bottom electrode 302 create an acoustic impedance mismatch on one side of the edge of the channel 306, effectively reducing energy loss and improving the Q value; simultaneously, the support effect and structural strength are superior. It can be understood that in other embodiments, the end of the reinforcing structure 3042 may only extend to the side of the piezoelectric layer 303.

[0060] When the top electrode 304 extends to form the reinforcing structure 3042, in order to avoid short circuit between the top electrode 304 and the bottom electrode 302, the top electrode 304 is disconnected at the edge of the effective resonant region to form an annular insulating groove 3043, thereby disconnecting its electrical connection with the reinforcing structure 3042.

[0061] Figure 7 This is a cross-sectional schematic diagram of an acoustic resonator 400 according to another embodiment of the present invention. It includes a substrate 401, a bottom electrode 402, a piezoelectric layer 403, a top electrode 404, a resonant cavity 405, a channel 406, and a release hole 407. Unlike the previous embodiment, this embodiment further includes a passivation layer 408 disposed on the upper side of the top electrode 404. A reinforcing structure 4082 disposed on the sidewall of the channel 406 is integrally formed with the passivation layer 408 and extends towards the substrate 401 to the side of the bottom electrode 402, ultimately becoming flush with the bottom plane of the bottom electrode 402. At this time, the top electrode 404, the piezoelectric layer 403, and the bottom electrode 402 form an acoustic impedance mismatch on one side of the edge of the channel 406, effectively reducing energy loss and improving the Q value; simultaneously, the support effect and structural strength are superior. It can be understood that in other embodiments, the end of the reinforcing structure 4082 may only extend to the side of the piezoelectric layer 403 or the side of the top electrode 404.

[0062] Figure 8This is a cross-sectional schematic diagram of an acoustic resonator 500 according to another embodiment of the present invention, which includes a substrate 501, a bottom electrode 502, a piezoelectric layer 503, a top electrode 504, a resonant cavity 505, a channel 506, and a release hole 507. In this embodiment, the reinforcing structure on the sidewall of the channel 506 is integrally formed with the top electrode 504 and extends towards the substrate 501 to a height below the lower surface of the bottom electrode 502, but does not contact the substrate. Its end is finally located at a height slightly higher than the upper surface of the substrate 501 inside the resonant cavity 505, leaving a certain gap between it and the bottom of the resonant cavity 505. At this time, in addition to effectively reducing energy loss and improving the Q value, it can also further improve the support effect and structural strength.

[0063] In a more preferred embodiment, reference may be made to Figure 8 The end of the reinforcing structure of the resonator 500 is further bent horizontally, giving it an end parallel to the substrate, which further improves the support effect and structural strength.

[0064] Figure 9 This is a top view of an acoustic resonator 600 according to another embodiment of the present invention. Figure 10 for Figure 9 The schematic diagram of the DD cross-section of the resonator 600 shown includes a substrate 601, a bottom electrode 602, a bottom electrode connection portion 6021, a piezoelectric layer 603, a top electrode 604, a top electrode connection portion 6041, a resonant cavity 605, a channel 606, a release hole 607, and a reinforcing structure 6042. The reinforcing structure 6042 is integrally formed with the top electrode 604 and extends downward to be flush with the lower surface of the bottom electrode 602, covering the piezoelectric layer 603 and the side of the bottom electrode 602. See also... Figure 9 In this embodiment, the shape of the edge of the channel 606 is the same as that of the top electrode 604, both being pentagonal. However, the channel 606 is rotated by a certain angle relative to the top electrode 604, so that the upper edge of the channel 606 is not parallel to the outer edge of the effective resonant region. At this time, the shortest distance between the upper edge of the channel and the corresponding outer edge of the effective resonant region is different at different positions, which can effectively increase the length of the transverse wave reflection path, thereby reducing energy loss and improving the Q value.

[0065] This embodiment does not limit the shape of the channel. In other embodiments, the cross-sectional shape of the channel is other shapes, such as circles, ellipses or polygons, or it can be set to be the same as the outer edge shape of the effective resonant region.

[0066] The present invention does not limit the relative position of the resonant cavity and the substrate. In specific embodiments, the resonant cavity can be disposed above the substrate to form an above-ground resonant cavity, such as resonator 600; or it can be disposed inside the substrate to form an underground resonant cavity, such as resonator 100.

[0067] In other embodiments, helium gas is filled into the resonant cavity to improve heat dissipation efficiency.

[0068] According to another aspect of the present invention, a method for manufacturing an acoustic resonator is provided for manufacturing the above-mentioned resonator device, specifically comprising the following steps:

[0069] Provide a substrate, and form a sacrificial layer within or on the substrate;

[0070] A resonant functional layer is provided, which is formed above a sacrificial layer and a substrate. The resonant functional layer includes at least a bottom electrode, a piezoelectric layer and a top electrode stacked together. A channel is formed through the resonant functional layer during the formation of the resonant functional layer.

[0071] A release hole is formed that communicates with the sacrificial layer. The release sacrificial layer forms a resonant cavity, which is connected to the channel. The release hole is connected to the channel through the resonant cavity. The region where the resonant functional layer overlaps with the resonant cavity is defined as the effective resonant region.

[0072] In another embodiment, the method of manufacturing an acoustic resonator further includes setting the minimum distance between the edge of the channel and the outer edge of the resonant functional layer to be greater than zero, so that the resonant functional layer surrounds the channel.

[0073] In another embodiment, the method of manufacturing an acoustic resonator further includes forming a reinforcing structure on the sidewall of the channel, the reinforcing structure extending at least along the side of any one of the resonant functional layers to the side of another layer in the resonant functional layer.

[0074] In another embodiment, the method of manufacturing an acoustic resonator further includes the step of encapsulating the resonator, and filling the encapsulation with helium gas during the encapsulation of the resonator.

[0075] Figures 11a-11g This is a schematic diagram illustrating the manufacturing process of an acoustic resonator in another specific embodiment of the present invention. The resonator manufactured in this embodiment has a channel penetrating the resonant functional layer and communicating with the resonant cavity, and has a reinforcing structure integrally formed with the top electrode, extending towards the substrate, covering the side of the bottom electrode, and flush with the lower surface of the bottom electrode. The specific steps of its manufacturing process include:

[0076] like Figure 11aAs shown, a substrate 701 is provided, and a sacrificial layer 705' is formed on the substrate 701. The substrate 701 includes a high-resistivity Si substrate, or it can be a Ge, SiGe, SiO2, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductors, quartz, glass, single crystal AlN, LiNbO3, TaNbO3, lead zirconate titanate [PZT] (Pb(Zr,Ti)O3), sapphire, diamond or alumina ceramic materials, and also includes multilayer structures composed of these semiconductors, or it can be silicon-on-insulator (SOI), silicon-on-insulator stacked (SSOI), silicon-on-insulator stacked germanium (S-SiGeOI), silicon-on-insulator germanium (SiGeOI), and germanium-on-insulator (GeOI), or it can also be a double-side polished wafer (DSP), preferably high-resistivity Si; the sacrificial layer can be a dielectric material such as SiO2, PSG, Si, Si3N4, PI, etc.

[0077] like Figure 11b As shown, a bottom electrode 702 is formed on the sacrificial layer 705'.

[0078] like Figure 11c As shown, the first portion 706a of the channel is formed by etching the bottom electrode 702 toward the substrate 701 to the sacrificial layer 705'.

[0079] like Figure 11d As shown, a piezoelectric layer 703 is formed on the bottom electrode 702 and within the first portion 706a of the channel. The material of the piezoelectric layer 703 can be zinc oxide (ZnO), zinc sulfide (ZnS), aluminum nitride (AlN), cadmium sulfide (CdS), lead titanate [PT] (PbTiO3), lead zirconate titanate [PZT] (Pb(Zr,Ti)O3), lithium tantalate (LiTaO3), or other members of the lead zirconate titanate lanthanum series. The piezoelectric layer can also be doped with other elements to change its piezoelectricity, such as doping with scandium, yttrium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, etc., with scandium being preferred. The piezoelectric material of the piezoelectric layer can be a single layer of piezoelectric material or multiple sublayers of the same or different piezoelectric materials.

[0080] like Figure 11e As shown, the piezoelectric layer 703 is etched towards the substrate 701 at the position corresponding to the first portion 706a of the channel to the sacrificial layer 705' or the bottom electrode 702, further forming the second portion 706b of the channel. In the horizontal direction, the cross-sectional area of ​​the second portion 706b of the channel can be larger than the cross-sectional area of ​​the first portion 706a of the channel.

[0081] like Figure 11fAs shown, a top electrode 704 is formed on the piezoelectric layer 703. In a further preferred embodiment, the top electrode 704 extends along the sidewalls of the second portion 706b and the first portion 706a of the channel to the sacrificial layer 705', forming a reinforcing structure 7042. The top electrode 704 is etched at the edge of the effective resonant region to insulate it from the bottom electrode 702. In optional examples, the materials of the bottom electrode layer and the top electrode layer can be gold (Au), molybdenum (Mo), ruthenium (Ru), aluminum (Al), platinum (Pt), titanium (Ti), tungsten (W), palladium (Pd), chromium (Cr), nickel (Ni), etc.; preferably, it can be molybdenum (Mo). Furthermore, both the top electrode layer and the bottom electrode layer can be a single layer of metal or multiple layers of metal, and the materials of the multiple layers of metal can be the same or different. The materials, thicknesses, etc., of the top electrode layer and the bottom electrode layer can be the same or different.

[0082] like Figure 11g As shown, at the edge of the resonator, the sacrificial layer 705' is etched towards the substrate 701 to form a release hole 707. The area where the first part 706a and the second part 706b of the channel project to overlap forms a channel 706 that penetrates the resonant functional layer. The channel 706 is located at a position corresponding to the center of the resonant cavity. The reinforcing structure 7042 becomes the sidewall of the channel 706. The sacrificial layer 705' is released through the channel 706 and the release hole 707 to form the resonant cavity 705.

[0083] Although the steps of the method are listed in a certain order above, those skilled in the art will understand that the steps can be performed in a different order than described above, that is, in reverse or in parallel. Detailed descriptions of each structural layer can be found in the device description and will not be repeated here.

[0084] The resonator proposed in this invention features a channel that penetrates the resonant functional layer and communicates with the resonant cavity. Combined with a release hole, this allows for air cooling of the effective resonant region under temperature difference, improving temperature uniformity across different locations within the effective resonant region. The resonant functional layer surrounds the channel, eliminating the central heating area. Furthermore, one or more layers of a passivation layer, top electrode, and piezoelectric layer are selected to extend and form the sidewall of the channel, creating a reinforcing structure that supports the suspended resonant functional layer and enhances structural strength. Simultaneously, the acoustic impedance mismatch formed at the edge of the effective resonant region by the reinforcing structure reduces energy loss and improves the Q value. Even further, setting the shape of the channel edge and the outer edge of the resonant functional layer to be non-parallel or different extends the path length of transverse wave reflection, thereby reducing energy loss and improving the Q value.

[0085] Although the contents of this application have been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that any changes in form and detail made to this application without departing from the spirit and scope of this application as defined by the appended claims and without inventive effort are within the scope of protection of this application.

Claims

1. An acoustic resonator, characterized in that, include: Substrate; A resonant functional layer is disposed above the substrate, and the resonant functional layer includes at least a bottom electrode, a piezoelectric layer and a top electrode stacked together. A resonant cavity is disposed between the resonant functional layer and the substrate, and the region where the resonant functional layer and the resonant cavity overlap is defined as the effective resonant region. A release hole, which at least penetrates the piezoelectric layer and communicates with the resonant cavity; A channel extends through the resonant functional layer and communicates with the resonant cavity; the channel communicates with the release hole through the resonant cavity; in the horizontal direction, the maximum cross-sectional area of ​​the channel is greater than the maximum cross-sectional area of ​​the release hole. The center of gravity of the effective resonant region is located within the channel; the release hole is located outside the outer edge of the effective resonant region.

2. The acoustic resonator according to claim 1, characterized in that, The resonant functional layer is arranged around the channel.

3. The acoustic resonator according to claim 1, characterized in that, The channel is positioned at a location corresponding to the center of the resonant cavity.

4. The acoustic resonator according to claim 1, characterized in that, The sidewall of the channel is provided with a reinforcing structure, which extends at least along the side of any one of the resonant functional layers to the side of another layer of the resonant functional layer.

5. The acoustic resonator according to claim 4, characterized in that, The reinforcing structure extends toward the substrate.

6. The acoustic resonator according to claim 5, characterized in that, The reinforcing structure extends at least to the side of the bottom electrode.

7. The acoustic resonator according to claim 6, characterized in that, The reinforcing structure is integrally formed with the top electrode, and an insulating groove is provided between the top electrode and the reinforcing structure to achieve electrical insulation between the top electrode and the reinforcing structure.

8. The acoustic resonator according to claim 6, characterized in that, The reinforcing structure is integrally formed with the piezoelectric layer.

9. The acoustic resonator according to claim 6, characterized in that, The resonant functional layer also includes a passivation layer disposed above the top electrode, and the reinforcing structure is integrally formed with the passivation layer.

10. The acoustic resonator according to claim 5, characterized in that, The lowest point of the reinforcing structure is below the lower surface of the bottom electrode, and a gap is provided between it and the bottom of the resonant cavity.

11. The acoustic resonator according to claim 10, characterized in that, The end of the reinforcing structure bends horizontally.

12. The acoustic resonator according to claim 1, characterized in that, The edge of the channel is not parallel to the outer edge of the effective resonant region.

13. The acoustic resonator according to claim 1, characterized in that, The horizontal cross-sectional shape of the channel is circular, elliptical, or polygonal.

14. The acoustic resonator according to claim 1, characterized in that, The edge of the channel has the same shape as the outer edge of the effective resonant region.

15. The acoustic resonator according to claim 1, characterized in that, The resonant cavity is disposed above or inside the substrate.

16. The acoustic resonator according to claim 1, characterized in that, The resonant cavity is filled with helium gas.

17. A method for manufacturing an acoustic resonator, characterized in that, Includes the following steps: Provide a substrate, and form a sacrificial layer within or on the substrate; A resonant functional layer is provided, which is formed above a sacrificial layer and a substrate. The resonant functional layer includes at least a bottom electrode, a piezoelectric layer and a top electrode stacked together. A channel is formed through the resonant functional layer during the formation of the resonant functional layer. A release hole is formed that communicates with the sacrificial layer. The release sacrificial layer forms a resonant cavity, which is connected to the channel. The release hole is connected to the channel through the resonant cavity. The region where the resonant functional layer and the resonant cavity overlap is defined as the effective resonant region. In the horizontal direction, the maximum cross-sectional area of ​​the channel is greater than the maximum cross-sectional area of ​​the release hole; the center of gravity of the effective resonant region is located inside the channel; the release hole is located outside the outer edge of the effective resonant region.

18. The method for manufacturing an acoustic resonator according to claim 17, characterized in that, The minimum distance between the edge of the channel and the outer edge of the resonant functional layer is greater than zero.

19. The method for manufacturing an acoustic resonator according to claim 17, characterized in that, It also includes forming a reinforcing structure on the sidewall of the channel, the reinforcing structure extending at least along the side of any one of the resonant functional layers to the side of another layer of the resonant functional layer.

20. The method for manufacturing an acoustic resonator according to claim 17, characterized in that, It also includes encapsulating the resonator and filling the encapsulation with helium gas during the encapsulation of the resonator.

21. A filter comprising an acoustic resonator according to any one of claims 1-16.

22. An electronic device comprising an acoustic resonator according to any one of claims 1-16.

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