Bulk acoustic wave resonator having void layer, manufacturing method thereof, filter, and electronic device

Abstract

The present application relates to a bulk acoustic wave resonator and a manufacturing method thereof. The resonator comprises a substrate, a bottom electrode, a top electrode, and a piezoelectric layer disposed between the bottom electrode and the top electrode, wherein: the bottom electrode is a gap electrode having a void layer, the void layer is at a distance from both a top surface and a bottom surface of the gap electrode in a thickness direction of the gap electrode, and the void layer forms an acoustic mirror cavity of the resonator or an acoustic mirror structure is disposed in the void layer; the substrate is provided with at least one electrically connecting through hole, one end of the through hole is connected to the bottom electrode, and the other end is adapted to be connected to a pad located on the lower side of the substrate. The present application also relates to a filter having the above-mentioned resonator and an electronic device having the filter or the resonator.

Description

Technical Field

[0001] Embodiments of the present invention relate to the semiconductor field, and more particularly to a bulk acoustic wave resonator and a method for manufacturing the same, a filter having the resonator, and an electronic device having the resonator or the filter. Background Technology

[0002] Electronic components, as fundamental elements of electronic devices, are widely used in mobile phones, automobiles, and home appliances. Furthermore, future world-changing technologies such as artificial intelligence, the Internet of Things, and 5G communications still rely on electronic components as their foundation.

[0003] Electronic devices, based on different working principles, can exhibit different characteristics and advantages. Among all electronic devices, those utilizing the piezoelectric effect (or inverse piezoelectric effect) are a very important category, with a wide range of applications. Film Bulk Acoustic Resonators (FBARs, also known as BAWs), as a key member of the piezoelectric family, are playing a vital role in the communications field. In particular, FBAR filters are gaining an increasingly larger market share in the radio frequency (RF) filter sector. FBARs possess excellent characteristics such as small size, high resonant frequency, high quality factor, large power capacity, and good roll-off effect. Their filters are gradually replacing traditional surface acoustic wave (SAW) filters and ceramic filters, playing a significant role in wireless communication RF applications. Their high sensitivity also extends to sensing fields such as biology, physics, and medicine.

[0004] The main structure of a thin-film bulk acoustic resonator (FBAR) is a "sandwich" structure consisting of an electrode-piezoelectric thin film-electrode, that is, a piezoelectric material sandwiched between two layers of metal electrodes. By inputting a sinusoidal signal between the two electrodes, the FBAR uses the inverse piezoelectric effect to convert the input electrical signal into mechanical resonance, and then uses the piezoelectric effect to convert the mechanical resonance into an electrical signal output.

[0005] The rapid development of communication technology requires continuously increasing filter operating frequencies. For example, the frequency of 5G communication bands (sub-6G) is between 3GHz and 6GHz, higher than that of 4G and other communication technologies. For bulk acoustic wave resonators and filters, higher operating frequencies mean that the film thickness, especially the electrode film thickness, needs to be further reduced. However, the main negative effect of reducing the electrode film thickness is the increase in electrical losses, leading to a decrease in the resonator Q value, especially the Q value at and near the series resonant point. Correspondingly, the performance of high-frequency bulk acoustic wave filters deteriorates significantly as the Q value of the bulk acoustic wave resonator decreases.

[0006] In addition, there is a need to increase the power capacity of filters and reduce the size of filters. Summary of the Invention

[0007] This invention is proposed to alleviate or solve the above-mentioned problems in the prior art, or to increase power capacity or reduce filter size.

[0008] According to one aspect of an embodiment of the present invention, a bulk acoustic resonator is provided, comprising:

[0009] A bulk acoustic resonator, comprising:

[0010] Base;

[0011] Bottom electrode;

[0012] Top electrode; and

[0013] A piezoelectric layer is disposed between the bottom electrode and the top electrode.

[0014] in:

[0015] The bottom electrode is a gap electrode, and the gap electrode has a void layer. In the thickness direction of the gap electrode, there is a distance between the void layer and both the top and bottom surfaces of the gap electrode. The void layer forms the acoustic mirror cavity of the resonator or an acoustic mirror structure is provided in the void layer.

[0016] The substrate is provided with at least one electrical connection via, one end of which is connected to the bottom electrode and the other end is adapted to be connected to a pad located on the underside of the substrate.

[0017] Embodiments of the present invention also relate to a filter, including the aforementioned bulk acoustic resonator.

[0018] Embodiments of the present invention also relate to a method for manufacturing a bulk acoustic resonator, comprising the steps of:

[0019] A substrate is provided, and a first bottom electrode layer is deposited on the upper side of the substrate;

[0020] A patterned sacrificial layer is formed on the first bottom electrode layer;

[0021] A second bottom electrode layer is deposited, which covers the sacrificial layer and the first bottom electrode layer, and the first bottom electrode layer and the second bottom electrode layer are electrically connected to each other.

[0022] The first and second bottom electrode layers are patterned to form the bottom electrode;

[0023] Deposit a piezoelectric layer and a top electrode layer, and pattern the top electrode layer to form the top electrode;

[0024] Release the sacrificial layer;

[0025] The conductive vias are etched through the substrate, and conductive pads electrically connected to the conductive vias are formed on the underside of the substrate.

[0026] Embodiments of the present invention also relate to an electronic device, including the filter described above, the resonator described above, or a bulk acoustic resonator manufactured according to the method described above. Attached Figure Description

[0027] The following description and accompanying drawings will better aid in understanding these and other features and advantages of the various embodiments disclosed herein, wherein the same reference numerals in the drawings always denote the same parts, wherein:

[0028] Figure 1 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention;

[0029] Figure 1A For an exemplary embodiment of the present invention, along Figure 1 A schematic cross-sectional view taken along line AA in the figure;

[0030] Figure 2 For another exemplary embodiment of the invention, along a path similar to Figure 1 A schematic cross-sectional view taken along the AA direction, showing multiple conductive vias;

[0031] Figure 3 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention;

[0032] Figure 3A For an exemplary embodiment of the present invention, along Figure 3 A schematic cross-sectional view taken along the AB direction in the figure;

[0033] Figure 4 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention;

[0034] Figure 4A For an exemplary embodiment of the present invention, along Figure 4 A schematic cross-sectional view taken along line AA in the figure;

[0035] Figure 5A-5I A schematic diagram illustrating the manufacturing process of a bulk acoustic resonator according to an exemplary embodiment of the present invention;

[0036] Figure 6A This is a schematic cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present invention, wherein a void seed layer is provided on the upper side of the void layer and a blocking layer is provided on the lower side;

[0037] Figure 6BThis is a schematic cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present invention, wherein a void seed layer is provided on the upper side of the void layer and a blocking layer is provided on the lower side;

[0038] Figure 6C This is a schematic cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present invention, wherein a void seed layer is provided on the upper side of the void layer and a blocking layer is provided on the lower side;

[0039] Figure 7A-7I This is a schematic diagram illustrating the manufacturing process of a bulk acoustic resonator according to another exemplary embodiment of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof.

[0041] Figure 1 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention. Figure 1A For an exemplary embodiment of the present invention, along Figure 1 A schematic cross-sectional view taken along line AA. Figure 1 and Figure 1A The labels for the attached figures are as follows:

[0042] 101: Substrate, with optional materials including single-crystal silicon, gallium arsenide, sapphire, quartz, etc.

[0043] 102: Bottom electrode, materials can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or composites or alloys of the above metals, etc.

[0044] 103: Acoustic mirror, which can be a cavity, or it can be a Bragg reflector layer or other equivalent forms.

[0045] 104: Piezoelectric thin film layer, which may be made of materials such as aluminum nitride, zinc oxide, PZT, etc., and contain rare earth element doping materials in a certain atomic ratio of the above materials.

[0046] 105: Top electrode, materials can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or composites of the above metals or their alloys, etc.

[0047] 106: Vias (also known as vias) etched into the substrate can be single or multiple.

[0048] 107: The bonding pad for electrical signals can be used for later packaging and can also be used to power the bottom electrode as part of the bottom electrode pin.

[0049] 108: Passivation layer on the surface of the top electrode.

[0050] 110: Crystal orientation seed layer, which can be AlN.

[0051] 111: Crystal orientation seed layer, which can be AlN.

[0052] It should be noted that while air gaps constitute a void layer, in this invention, the void layer can be not only an air gap layer, but also a vacuum gap layer, or a void layer filled with other gaseous media. Although not shown, in optional embodiments, if the space within the void layer is sufficient, an acoustic mirror structure, such as a Bragg reflector layer, can also be provided within the void layer.

[0053] It should be noted that the crystal orientation seed layers 110 and 111 and the passivation layer 108 in the above structure can be omitted.

[0054] exist Figure 1A In the illustrated embodiment, the conductive via 106 is located at the geometric center of the void layer. "Geometric center" here includes locations adjacent to the geometric center, such as within a radius of 10 μm centered on the geometric center. However, the conductive via 106 can also be located at other positions.

[0055] In this invention, the bottom electrode contains a void layer. This method of moving the acoustic reflection layer inside the electrode allows the bottom electrode to make complete contact with the substrate. Based on this, by etching a via structure into the substrate, electrical signals can be directly extracted from the bottom electrode of the resonator through the via. Filter products composed of resonators based on this invention do not require additional signal extraction structures (such as pads), thereby reducing the size of such products.

[0056] In this invention, optionally, the thickness of the void layer is... Within a certain range. In a further embodiment, the height of the void layer is made greater than the typical amplitude of the resonator (approximately 10 nm), and correspondingly, the height of the void layer is within a certain range. Within this range, it is beneficial for the acoustic energy decoupling between the top electrode and the resonant cavity (in this embodiment, it is a composite structure consisting of a top electrode, a piezoelectric layer, and a bottom electrode) when the resonator is operating at high power.

[0057] Figure 2 For another exemplary embodiment of the invention, along a path similar to Figure 1 A schematic cross-sectional view taken along line AA, showing multiple conductive vias. Figure 2In one embodiment, multiple conductive vias are electrically connected to the same conductive pad.

[0058] Figure 3 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention. Figure 3A For an exemplary embodiment of the present invention, along Figure 3 A schematic cross-sectional view taken along the AB direction.

[0059] Figure 3 and Figure 3A The resonator shown is Figure 1A The difference in the resonator shown is that the bottom electrode also extends laterally, thus having an extension, such as... Figure 3A and Figure 3 As shown, the bottom electrode 104 extends beyond the effective region of the resonator. This extension can be connected to the bottom electrodes of other resonators. In the illustrated embodiment, the conductive via 106 is located at the geometric center of the void layer. This location at the geometric center includes proximity to the geometric center, for example, within a radius of 10 μm centered on the geometric center. However, the conductive via 106 can also be located at other locations.

[0060] Figure 4 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention. Figure 4A For an exemplary embodiment of the present invention, along Figure 4 A schematic cross-sectional view taken along the AA direction.

[0061] exist Figure 4A and Figure 4 In the middle, a support structure 109 is provided within the void layer. The support structure can be made of the same material as the bottom electrode, or it can be made of a different material. For example... Figure 4A As shown, the support structure 109 is connected between the upper and lower sides of the void layer. The support structure can prevent the upper and lower electrode layers of the void layer from sticking together due to stress and other factors; on the other hand, it can accelerate the heat conduction of the resonator to the substrate.

[0062] It should be noted that the height of the support structure 109 can also be less than the height of the voids in the void layer. This can also prevent the upper and lower electrode layers of the void layer from sticking together due to stress and other factors. The support structure can be set at the geometric center of the void layer. Setting it at the geometric center includes being adjacent to the geometric center, for example, within a radius of 10 μm centered on the geometric center.

[0063] In the illustrated embodiment, the conductive via 106 and the support structure 109 do not overlap in the thickness direction of the resonator; however, the invention is not limited thereto. In an optional embodiment, the conductive via overlaps with the support structure in the projection of the resonator along the thickness direction. This overlap includes not only partial and complete overlap of their projections, but also cases where the lateral distance between their projection centers does not exceed 10 μm. In an optional embodiment, one conductive via 106 is located at the geometric center of the void layer. This location at the geometric center includes proximity to the geometric center, for example, within a radius of 10 μm centered on the geometric center.

[0064] Figure 5A-5I This is a schematic diagram illustrating the manufacturing process of a bulk acoustic resonator according to an exemplary embodiment of the present invention. Referring below... Figure 5A-5I An exemplary description of the manufacturing process of a bulk acoustic resonator.

[0065] First, such as Figure 5A As shown, a first seed layer 110, a first bottom electrode layer 102, and a sacrificial layer 112 are deposited on a substrate 101.

[0066] Secondly, such as Figure 5B As shown, the sacrificial layer 112 is graphically represented.

[0067] Next, as Figure 5C As shown, a second seed layer 111 is deposited.

[0068] See Figure 5D The second seed layer 111 is then graphically represented. Next, in... Figure 5E In the middle, a second bottom electrode layer 102 is deposited. Figure 5F In this process, the first bottom electrode layer and the second bottom electrode layer are patterned to form the final bottom electrode.

[0069] See Figure 5G A piezoelectric layer 104, a top electrode 105, and a passivation layer 108 are deposited, including patterning of the top electrode.

[0070] Next, as Figure 5H As shown, the sacrificial layer 112 is released to form a void layer, which can serve as the acoustic mirror cavity of the resonator.

[0071] See Figure 5I Conductive vias 106 are etched on the underside of the substrate, and conductive pads are deposited and patterned.

[0072] It should be noted that in the above method, the first seed layer and / or the second seed layer may not be set, and the passivation layer 108 may not be set.

[0073] Furthermore, the order of the above steps can be changed based on the actual situation. For example, the sacrificial layer 112 can be released after etching the vias and forming the conductive pads. Alternatively, the conductive vias 106 and conductive pads 107 can be formed first, or without forming a first seed layer, and then the first bottom electrode layer can be deposited. These are all within the scope of protection of this invention.

[0074] Figure 6A This is a schematic cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present invention, wherein a void seed layer is provided on the upper side of the void layer, a blocking layer is provided on the lower side, and a through hole is shown in the figure. Figure 6B The figure shows a schematic cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present invention, wherein a void seed layer is provided on the upper side of the void layer, a blocking layer is provided on the lower side, and three through holes are shown in the figure. Figure 6C This is a schematic cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present invention, wherein a void seed layer is provided on the upper side of the void layer, a blocking layer is provided on the lower side, and a support structure is shown in the figure.

[0075] Figures 6A-6C and Figure 3A , Figure 2 as well as Figure 4A They are similar, but the difference lies in... Figures 6A-6C In the middle, a gap seed layer 111 and a blocking layer 113 are set, while Figure 3A , Figure 2 as well as Figure 4A Only a gap seed layer 111 is set in the middle.

[0076] Figure 7A-7I This is a schematic diagram illustrating the manufacturing process of a bulk acoustic resonator according to another exemplary embodiment of the present invention. Referring below... Figure 7A-7I An exemplary description of the manufacturing process of a bulk acoustic resonator.

[0077] First, such as Figure 7A As shown, a first seed layer 110, a first bottom electrode layer 102, a barrier layer 113, and a sacrificial layer 112 are deposited on a substrate 101.

[0078] Secondly, such as Figure 7B As shown, the sacrificial layer 112 and the blocking layer 113 are graphically represented.

[0079] Next, as Figure 7C As shown, the seed layer 111 is a sedimentation void.

[0080] like Figure 7D As shown, the gap seed layer 111 is graphically represented.

[0081] like Figure 7E As shown, a second bottom electrode layer 102 is then deposited.

[0082] exist Figure 7F In this process, the first bottom electrode layer, the second bottom electrode layer, and the first seed layer 110 are patterned to form the final bottom electrode.

[0083] See Figure 7G A piezoelectric layer 104, a top electrode 105, and a passivation layer 108 are deposited, including patterning of the top electrode.

[0084] Next, as Figure 7H As shown, the sacrificial layer 112 is released to form a void layer 103, which can serve as an acoustic mirror cavity for the resonator.

[0085] See Figure 7I Conductive vias 106 are etched on the underside of the substrate, and conductive pads 107 are deposited and patterned.

[0086] Furthermore, the order of the above steps can be changed based on the actual situation. For example, the sacrificial layer 112 can be released after etching the vias and forming the conductive pads. Alternatively, the conductive vias 106 and conductive pads 107 can be formed first, followed by the deposition of the first bottom electrode layer. These are all within the scope of this invention.

[0087] In the bulk acoustic resonator manufacturing method of the present invention, the void layer in the bottom electrode is used as an acoustic mirror, thereby eliminating the need for the CMP (chemical mechanical polishing) process of forming an acoustic mirror cavity in the substrate.

[0088] Furthermore, by utilizing the through-hole 106 provided in the substrate to directly connect with the bottom electrode without the need for additional metal connection structures, the present invention can achieve lower signal transmission loss and lower electrical connection resistance.

[0089] When the support structure 109 is provided, the above-described method of the present invention may include the following steps: forming a support structure on the upper side of the substrate before forming a patterned sacrificial layer on the first bottom electrode layer; and in the step of "forming a patterned sacrificial layer on the first bottom electrode layer", the height of the support structure is not greater than the thickness of the sacrificial layer. The above-described deposition method for forming the support structure 109 (compared to CMP process, deposition process has excellent on-wafer uniformity, and the deposition rate does not change with pattern density) does not require deliberately increasing the thickness of the void layer to accommodate the errors of the CMP process. Therefore, without increasing the width of the support structure as much as possible (an excessively wide support structure would degrade resonator performance), the structure of this invention can obtain a support structure with a larger aspect ratio, that is, a more robust support structure. Furthermore, using the above method, the height of the support structure 109 can be effectively controlled, and it is also easy to achieve a fixed connection between the support structure 109 and the upper and lower sides.

[0090] It should be noted that the support structure does not necessarily need to be set before the formation of the sacrificial layer; it can also be set afterward. For example, after the sacrificial layer has been deposited, a small hole can be drilled in the middle of the sacrificial layer during patterning. Then, when depositing the second bottom electrode, such as Mo metal, the Mo metal will form a small Mo metal pillar in the hole, i.e., the support structure.

[0091] In this invention, when a void layer is provided in the bottom electrode, the effective region of the resonator is the overlapping region of the top electrode, bottom electrode, piezoelectric layer and void layer of the bottom electrode in the thickness direction of the resonator.

[0092] In this invention, the numerical range mentioned can be not only the endpoint values, but also the median or other values ​​between the endpoint values, all of which are within the protection scope of this invention.

[0093] In this invention, there is no need to add an additional signal output structure. Instead, the signal is directly led out from the bottom of the resonator, thereby reducing the size of the resonator. Furthermore, the thinning of the air cavity, which serves as the acoustic mirror, can further reduce the size.

[0094] The bottom electrode of this invention is directly mounted on the substrate, which facilitates heat transfer. Simultaneously, the thinner air cavity allows heat from the resonator body to be easily radiated to the bottom electrode. The support structure also improves thermal conductivity. These features enhance heat dissipation and meet the power requirements of the device.

[0095] As will be understood by those skilled in the art, the bulk acoustic resonator according to the present invention can be used to form a filter.

[0096] Based on the above, the present invention proposes the following technical solution:

[0097] 1. A bulk acoustic resonator, comprising:

[0098] Base;

[0099] Bottom electrode;

[0100] Top electrode; and

[0101] A piezoelectric layer is disposed between the bottom electrode and the top electrode.

[0102] in:

[0103] The bottom electrode is a gap electrode, and the gap electrode has a void layer. In the thickness direction of the gap electrode, there is a distance between the void layer and both the top and bottom surfaces of the gap electrode. The void layer forms the acoustic mirror cavity of the resonator or an acoustic mirror structure is provided in the void layer.

[0104] The substrate is provided with at least one electrical connection via, one end of which is connected to the bottom electrode and the other end is adapted to be connected to a pad located on the underside of the substrate.

[0105] 2. The resonator according to 1, wherein:

[0106] The void layer is an air void layer or a vacuum void layer.

[0107] 3. The resonator according to 1, wherein:

[0108] The thickness of the void layer is Within the range.

[0109] 4. The resonator according to 3, wherein:

[0110] The thickness of the void layer is Within the range.

[0111] 5. The resonator according to claim 1, wherein:

[0112] The bottom electrode is located entirely on the upper surface of the substrate.

[0113] 6. The resonator according to claim 1, wherein:

[0114] At least one of the through holes is disposed below the bottom electrode to be directly connected to the bottom electrode in the thickness direction of the resonator; or

[0115] In the projection along the thickness direction of the resonator, at least one of the through holes is located within the effective region of the resonator.

[0116] 7. The resonator according to any one of 1-6, wherein:

[0117] A first crystal orientation seed layer is provided between the bottom electrode and the substrate, and the through hole penetrates the first crystal orientation seed layer.

[0118] 8. The resonator according to any one of 1-6, wherein:

[0119] A support structure is provided within the void layer.

[0120] 9. The resonator according to 8, wherein:

[0121] The support structure connects the upper and lower sides of the void layer.

[0122] 10. The resonator according to 9, wherein:

[0123] The support structure is a heat-conducting structure.

[0124] 11. The resonator according to 10, wherein:

[0125] The support structure is located at the geometric center of the void layer.

[0126] 12. The resonator according to 11, wherein:

[0127] One of the at least one electrical connection vias overlaps with the support structure in the projection of the resonator along the thickness direction.

[0128] 13. The resonator according to any one of 1-6, wherein:

[0129] The bottom electrode has a bottom electrode extension that extends laterally beyond the effective region of the resonator.

[0130] 14. The resonator according to any one of 1-6, wherein:

[0131] A barrier layer is provided on the lower side of the void layer, the barrier layer defining the lower boundary of the void layer; and / or

[0132] A void seed layer is provided on the upper side of the void layer, and the void seed layer defines the upper boundary of the void layer.

[0133] 15. A filter comprising a bulk acoustic resonator according to any one of 1-14.

[0134] 16. The filter according to 15, wherein:

[0135] The filter includes two bulk acoustic wave resonators according to 13, the bottom electrodes of the two bulk acoustic wave resonators being electrically connected to each other via the bottom electrode extension.

[0136] 17. A method for manufacturing a bulk acoustic resonator, comprising the following steps:

[0137] A substrate is provided, and a first bottom electrode layer is deposited on the upper side of the substrate;

[0138] A patterned sacrificial layer is formed on the first bottom electrode layer;

[0139] A second bottom electrode layer is deposited, which covers the sacrificial layer and the first bottom electrode layer, and the first bottom electrode layer and the second bottom electrode layer are electrically connected to each other.

[0140] The first and second bottom electrode layers are patterned to form the bottom electrode;

[0141] Deposit a piezoelectric layer and a top electrode layer, and pattern the top electrode layer to form the top electrode;

[0142] Release the sacrificial layer;

[0143] The conductive vias are etched through the substrate, and conductive pads electrically connected to the conductive vias are formed on the underside of the substrate.

[0144] 18. According to the method described in 17, wherein:

[0145] Before depositing the first bottom electrode layer, the method further includes the steps of: depositing and patterning a first crystal orientation seed layer on the substrate side, wherein the first bottom electrode layer is deposited over the first crystal orientation seed layer; and

[0146] In the step of "etching conductive vias through the substrate", the conductive vias pass through the first crystal orientation seed layer.

[0147] 19. According to the method described in 17, wherein:

[0148] The method further includes the step of: forming a support structure on the upper side of the base; and

[0149] In the step of “forming a patterned sacrificial layer on the first bottom electrode layer”, the height of the support structure is not greater than the thickness of the sacrificial layer.

[0150] 20. The method according to any one of 17-19, wherein:

[0151] Prior to the step "forming a patterned sacrificial layer on the first bottom electrode layer", the method further includes providing a patterned barrier layer on the first bottom electrode layer, and the step "forming a patterned sacrificial layer on the first bottom electrode layer" includes forming a patterned sacrificial layer on the barrier layer; and / or

[0152] Prior to the step "deposit second bottom electrode layer", the method further includes setting a patterned void seed layer on the sacrificial layer, and the step "deposit second bottom electrode layer" includes depositing a second bottom electrode layer on the void seed layer.

[0153] 21. An electronic device comprising a filter according to 15 or 16, or a resonator according to any one of 1-14, or a resonator manufactured by any one of 17-20.

[0154] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that variations may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bulk acoustic resonator, comprising: Base; Bottom electrode; Top electrode; and A piezoelectric layer is disposed between the bottom electrode and the top electrode. in: The bottom electrode is a gap electrode, and the gap electrode has a void layer. In the thickness direction of the gap electrode, there is a distance between the void layer and both the top and bottom surfaces of the gap electrode. The void layer forms the acoustic mirror cavity of the resonator or an acoustic mirror structure is provided in the void layer. The substrate is provided with at least one electrical connection via, one end of which is connected to the bottom electrode and the other end is adapted to be connected to a pad located on the underside of the substrate. The void layer is spaced apart from the substrate in the thickness direction of the substrate, and the bottom electrode between the void layer and the substrate is located on the side of the substrate facing the piezoelectric layer.

2. The resonator according to claim 1, wherein: The void layer is an air void layer or a vacuum void layer.

3. The resonator according to claim 1, wherein: The thickness of the void layer is in the range of 50 Å to 10000 Å.

4. The resonator according to claim 3, wherein: The thickness of the void layer is in the range of 100 Å to 5000 Å.

5. The resonator according to claim 1, wherein: The bottom electrode is located entirely on the upper surface of the substrate.

6. The resonator according to claim 1, wherein: At least one of the through holes is disposed below the bottom electrode to be directly connected to the bottom electrode in the thickness direction of the resonator; or In the projection along the thickness direction of the resonator, at least one of the through holes is located within the effective region of the resonator.

7. The resonator according to any one of claims 1-6, wherein: A first crystal orientation seed layer is provided between the bottom electrode and the substrate, and the through hole penetrates the first crystal orientation seed layer.

8. The resonator according to any one of claims 1-6, wherein: A support structure is provided within the void layer.

9. The resonator according to claim 8, wherein: The support structure connects the upper and lower sides of the void layer.

10. The resonator according to claim 9, wherein: The support structure is a heat-conducting structure.

11. The resonator according to claim 10, wherein: The support structure is located at the geometric center of the void layer.

12. The resonator according to claim 11, wherein: One of the at least one electrical connection vias overlaps with the support structure in the projection of the resonator along the thickness direction.

13. The resonator according to any one of claims 1-6, wherein: The bottom electrode has a bottom electrode extension that extends laterally beyond the effective region of the resonator.

14. The resonator according to any one of claims 1-6, wherein: A barrier layer is provided on the lower side of the void layer, the barrier layer defining the lower boundary of the void layer; and / or A void seed layer is provided on the upper side of the void layer, and the void seed layer defines the upper boundary of the void layer.

15. A filter comprising a bulk acoustic resonator according to any one of claims 1-14.

16. The filter according to claim 15, wherein: The filter includes two bulk acoustic wave resonators according to claim 13, the bottom electrodes of the two bulk acoustic wave resonators being electrically connected to each other via the bottom electrode extension.

17. A method for manufacturing a bulk acoustic resonator, comprising the steps of: A substrate is provided, and a first bottom electrode layer is deposited on the upper side of the substrate; A patterned sacrificial layer is formed on the first bottom electrode layer; A second bottom electrode layer is deposited, which covers the sacrificial layer and the first bottom electrode layer, and the first bottom electrode layer and the second bottom electrode layer are electrically connected to each other. The first and second bottom electrode layers are patterned to form the bottom electrode; Deposit a piezoelectric layer and a top electrode layer, and pattern the top electrode layer to form the top electrode; The sacrificial layer is released to form a void layer, the void layer being spaced apart from the substrate in the thickness direction of the substrate, and the bottom electrode between the void layer and the substrate being located on the side of the substrate facing the piezoelectric layer; The conductive vias are etched through the substrate, and conductive pads electrically connected to the conductive vias are formed on the underside of the substrate.

18. The method of claim 17, wherein: Before depositing the first bottom electrode layer, the method further includes the step of: depositing a first crystal orientation seed layer on the substrate side, wherein the first bottom electrode layer is deposited to cover the first crystal orientation seed layer; and In the step of "etching conductive vias through the substrate", the conductive vias pass through the first crystal orientation seed layer.

19. The method of claim 17, wherein: The method further includes the step of: forming a support structure on the upper side of the base; and In the step of "forming a patterned sacrificial layer on the first bottom electrode layer", the height of the support structure is not greater than the thickness of the sacrificial layer.

20. The method according to any one of claims 17-19, wherein: Prior to the step "forming a patterned sacrificial layer on the first bottom electrode layer", the method further includes providing a patterned barrier layer on the first bottom electrode layer, and the step "forming a patterned sacrificial layer on the first bottom electrode layer" includes forming a patterned sacrificial layer on the barrier layer; and / or Prior to the step "deposit second bottom electrode layer", the method further includes setting and patterning a void seed layer on the sacrificial layer, and the step "deposit second bottom electrode layer" includes depositing a second bottom electrode layer on the void seed layer.

21. An electronic device comprising a filter according to claim 15 or 16, or a resonator according to any one of claims 1-14, or a resonator manufactured by the method according to any one of claims 17-20.

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