Bulk acoustic wave resonator, bulk acoustic wave filter

Abstract

A bulk acoustic wave resonator (200) comprises: a first layer, wherein the first layer comprises a first cavity located on a first side; a first electrode layer located on the first side, a first end of the first electrode layer contacts the first layer, and a second end of the first electrode layer is located in the first cavity; a second layer located on the first electrode layer; and a second electrode layer located on the second layer, wherein a first portion of the first electrode layer that overlaps with the second electrode layer is located in the first cavity. Since the resonance region (209) has no overlap with the first layer, the resonance region (209) is suspended relative to the first cavity, which can improve the difference in acoustic impedance between the resonance region (209) and the non-resonance region, thereby improving the Q value of the resonant device. In addition, the second layer comprises a piezoelectric layer (205), and the piezoelectric layer (205) does not include a crystal with obvious steering, thereby helping to improve the electromechanical coupling coefficient and Q value of the resonant device.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a bulk acoustic wave resonator device and a bulk acoustic wave filter device. Background Art

[0002] The RF (Radio Frequency, RF) front-end chips of wireless communication equipment include power amplifiers, antenna switches, RF filters, duplexers, multiplexers and low noise amplifiers. Among them, RF filters include surface acoustic wave (Surface Acoustic Wave, SAW) filters, bulk acoustic wave (Bulk Acoustic Wave, BAW) filters, micro-electro-mechanical system (Micro-Electro-Mechanical System, MEMS) filters, integrated passive devices (Integrated Passive Devices, IPD) filters, etc. SAW resonators and BAW resonators have high quality factors (Q values). The low insertion loss and high out-of-band suppression RF filters made of SAW resonators and BAW resonators, namely SAW filters and BAW filters, are the mainstream RF filters currently used in wireless communication equipment such as mobile phones and base stations. Among them, the Q value is the quality factor value of the resonator, which is defined as the center frequency divided by the 3dB bandwidth of the resonator. The operating frequency of SAW filters is generally 0.4GHz to 2.7GHz, and the operating frequency of BAW filters is generally 0.7GHz to 7GHz.

[0003] Compared with SAW resonators, BAW resonators have better performance, but due to the complex process steps, the manufacturing cost of BAW resonators is higher than that of SAW resonators. However, as wireless communication technology gradually evolves, more and more frequency bands are used. At the same time, with the application of frequency band superposition technologies such as carrier aggregation, the mutual interference between wireless frequency bands has become more and more serious. High-performance BAW technology can solve the problem of mutual interference between frequency bands. With the advent of the 5G era, wireless mobile networks have introduced higher communication frequency bands. Currently, only BAW technology can solve the filtering problem of high-frequency bands.

[0004] Figure 1aA BAW filter circuit is shown, including a ladder circuit composed of multiple BAW resonators, wherein f1, f2, f3, and f4 represent four different frequencies, respectively. In each BAW resonator, the metal electrodes on both sides of the piezoelectric layer of the resonator generate alternating positive and negative voltages, and the piezoelectric layer generates sound waves through the alternating positive and negative voltages. The sound waves in the resonator propagate in a direction perpendicular to the piezoelectric layer. In order to form resonance, the sound wave needs to be totally reflected at the upper surface of the upper metal electrode and the lower surface of the lower metal electrode to form a standing sound wave. The condition for the reflection of the sound wave is that the acoustic impedance of the contact area with the upper surface of the upper metal electrode and the lower surface of the lower metal electrode is significantly different from the acoustic impedance of the metal electrode.

[0005] Film Bulk Acoustic Wave Resonator (FBAR) is a BAW resonator that can confine the energy of acoustic waves within the device. The resonator has air above the resonance area and a cavity below. The acoustic impedance of air is quite different from that of metal electrodes, so the acoustic waves can be fully reflected on the upper surface of the upper metal electrode and the lower surface of the lower metal electrode, forming standing waves.

[0006] Figure 1b A schematic diagram of the cross-section A structure of an FBAR 100 is shown. The FBAR 100 includes: a substrate 101, the substrate 101 includes a cavity 101a; and an active layer 103, which is located on the substrate 101. The active layer 103 includes a piezoelectric layer 105 and electrode layers 107 (i.e., a lower electrode layer) and 109 (i.e., an upper electrode layer) respectively located on both sides of the piezoelectric layer 105, wherein the electrode layer 107 contacts the substrate 101. The resonance region 111 on the active layer 103 has an overlapped portion with the substrate 101, so the resonance region 111 is not suspended relative to the cavity 101a. If the acoustic impedance of the resonance region 111 is similar to that of the non-resonance region, the energy of the resonance region 111 will diffuse to the non-resonance region, thereby causing the Q value of the resonator to decrease. In addition, since the electrode layer 107 is raised, forming the piezoelectric layer 105 directly on the electrode layer 107 will cause some crystals in the piezoelectric layer 105 (for example, crystals at the edges on both sides of the piezoelectric layer 105 in the horizontal direction) to be significantly turned and not parallel to other crystals, thereby reducing the electromechanical coupling coefficient and Q value of the FBAR. Summary of the invention

[0007] The technical problem solved by the present invention is to provide a bulk acoustic wave resonator device, wherein the resonant region of the bulk acoustic wave resonator device is suspended relative to the cavity on the intermediate layer or the support layer or the substrate, so as to improve the difference in acoustic impedance between the resonant region and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the piezoelectric layer of the bulk acoustic wave resonator device does not include crystals with obvious steering, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0008] To solve the above technical problems, an embodiment of the present invention provides a bulk acoustic wave resonance device, comprising: a first layer, the first layer comprising a first cavity located on a first side; a first electrode layer, a first end of the first electrode layer contacts the first layer, and a second end of the first electrode layer is located in the first cavity; a second layer, located on the first side and on the first electrode layer, the second layer is a flat layer, covering the first cavity; and a second electrode layer, located on the first side and on the second layer, wherein a first portion of the first electrode layer overlapping with the second electrode layer is located in the first cavity.

[0009] It should be noted that by adjusting the positions of the first electrode layer and the second electrode layer so that there is no overlapping contact between the resonance zone and the first layer, the resonance zone is suspended relative to the first cavity, which can increase the difference in acoustic impedance between the resonance zone and the non-resonance zone and improve the Q value of the resonance device.

[0010] In some embodiments, the first layer further includes: an intermediate layer, the intermediate layer including the first cavity. In some embodiments, the material of the intermediate layer includes but is not limited to at least one of the following: a polymer, an insulating dielectric. In some embodiments, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), a photosensitive epoxy resin photoresist (e.g., SU-8), and a polyimide. In some embodiments, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, and titanium oxide. In some embodiments, the thickness of the intermediate layer includes but is not limited to: 0.1 microns to 10 microns.

[0011] In some embodiments, the first layer further includes: a support layer, the support layer including the first cavity. In some embodiments, the material of the support layer includes but is not limited to at least one of the following: a polymer, an insulating dielectric. In some embodiments, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), a photosensitive epoxy resin photoresist (e.g., SU-8), and polyimide. In some embodiments, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, and titanium oxide. In some embodiments, the thickness of the support layer includes but is not limited to: 20 microns to 100 microns.

[0012] In some embodiments, the first layer further comprises: a first substrate, the first substrate comprising the first cavity. In some embodiments, the material of the first substrate includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0013] In some embodiments, the first layer also includes: an etching shielding layer, which at least covers the bottom or sidewall of the first cavity. In some embodiments, the material of the etching shielding layer includes but is not limited to at least one of the following: aluminum nitride, silicon carbide, diamond, silicon nitride, silicon dioxide, aluminum oxide, titanium dioxide. In some embodiments, the thickness of the etching shielding layer includes but is not limited to: 0.1 micron to 3 microns. In some embodiments, the thickness of the etching shielding layer includes but is not limited to: 2 microns to 6 microns. It should be noted that the etching shielding layer can protect the intermediate layer or the supporting layer or the first substrate when etching to form the first cavity. In addition, the etching shielding layer can protect the resonance device from corrosion by water and oxygen.

[0014] In some embodiments, the first layer further includes a first groove located on the first side, the first groove is located on one side of the first cavity in the horizontal direction and communicates with the first cavity, and the first end is located in the first groove. It should be noted that the depth of the first groove is less than the depth of the first cavity, and the depth of the first groove at least corresponds to the thickness of the first electrode layer (for example, the depth of the first groove is equal to the thickness of the first electrode layer or the sum of the thickness of the first electrode layer and the thickness of the etching shielding layer).

[0015] In some embodiments, the second layer includes: a piezoelectric layer, the piezoelectric layer includes a plurality of crystals, the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals; a first coordinate axis along the first direction corresponds to the height of the first crystal, and a second coordinate axis along the second direction corresponds to the height of the second crystal, wherein the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means: the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means: the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0016] In some embodiments, the first crystal corresponds to a first coordinate system, which includes the first coordinate axis and a third coordinate axis along a third direction; the second crystal corresponds to a second coordinate system, which includes the second coordinate axis and a fourth coordinate axis along a fourth direction.

[0017] In some embodiments, the first coordinate system further includes a fifth coordinate axis along a fifth direction, and the second coordinate system further includes a sixth coordinate axis along a sixth direction. In some embodiments, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0018] In some embodiments, the material of the piezoelectric layer includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0019] In some embodiments, the second layer includes: a piezoelectric layer, the piezoelectric layer includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to indicate the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the half-peak width (Full Width at Half Maximum, FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0020] It should be noted that forming the piezoelectric layer on a plane can prevent the piezoelectric layer from including crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0021] In some embodiments, a second portion of the second electrode layer overlapping with the first electrode layer is located above the first cavity, and a projection of the second portion perpendicular to the first layer is located within the first cavity.

[0022] In some embodiments, the material of the first electrode layer includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the second electrode layer includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0023] In some embodiments, the first electrode layer includes a first polarity, and the second electrode layer includes a second polarity. In some embodiments, the first electrode layer includes the first polarity and the second polarity, and the second electrode layer includes the first polarity and the second polarity. The first polarity and the second polarity are different. It should be noted that the electrode polarity includes positive and negative electrodes.

[0024] In some embodiments, the resonant device further comprises: a second substrate, located on a second side of the first layer, the second side being opposite to the first side. In some embodiments, the material of the second substrate includes but is not limited to at least one of the following: silicon, silicon carbide, and glass. It should be noted that the acoustic impedance of the first layer may be small, thereby preventing sound waves from leaking from the resonance region into the second substrate.

[0025] In some embodiments, the resonant device further comprises: a thin film located between the first layer and the second substrate. In some embodiments, the thin film includes but is not limited to: a polycrystalline thin film. In some embodiments, the material of the polycrystalline thin film includes but is not limited to at least one of the following: polycrystalline silicon, polycrystalline silicon nitride, polycrystalline silicon carbide. It should be noted that the thin film helps to prevent the formation of a free electron layer on the surface of the second substrate, thereby reducing the electrical loss caused by the second substrate.

[0026] An embodiment of the present invention further provides a bulk acoustic wave filter device, comprising: a bulk acoustic wave resonance device provided by at least one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a is a schematic diagram of a bulk acoustic wave filter circuit;

[0028] Figure 1b is a schematic diagram of the cross-section A structure of a FBAR 100;

[0029] Figure 2 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 200 according to an embodiment of the present invention;

[0030] Figure 3 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 300 according to an embodiment of the present invention;

[0031] Figure 4 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 400 according to an embodiment of the present invention;

[0032] Figure 5 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 500 according to an embodiment of the present invention;

[0033] Figure 6is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 600 according to an embodiment of the present invention;

[0034] Figure 7 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 700 according to an embodiment of the present invention;

[0035] Figure 8 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 800 according to an embodiment of the present invention;

[0036] Fig. 9 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 900 according to an embodiment of the present invention;

[0037] Fig.10 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 1000 according to an embodiment of the present invention;

[0038] Fig.11 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 1100 according to an embodiment of the present invention;

[0039] Fig.12 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 1200 according to an embodiment of the present invention;

[0040] Fig.13 It is a schematic diagram of the structure of a hexagonal crystal;

[0041] Fig.14 (i) is a schematic diagram of the structure of an orthorhombic crystal;

[0042] Fig.14 (ii) is a schematic diagram of the structure of a tetragonal crystal;

[0043] Fig.14 (iii) is a schematic diagram of the structure of a cubic crystal. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0045] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] As mentioned in the background section, see Figure 1b, the resonance zone 111 is not suspended relative to the cavity 101a, and has an overlapped portion with the substrate 101. If the acoustic impedance of the resonance zone 111 is similar to the acoustic impedance of the non-resonance zone, the energy of the resonance zone 111 will diffuse to the non-resonance zone, thereby reducing the Q value of the resonator. In addition, since the electrode layer 107 is raised, the piezoelectric layer 105 is formed directly on the electrode layer 107, which will cause some crystals in the piezoelectric layer 105 (for example, crystals at the edges of both sides of the piezoelectric layer 105 in the horizontal direction) to turn significantly and become non-parallel to other crystals, thereby reducing the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0047] The inventors of the present invention discovered that by adjusting the positions of the two electrode layers so that there is no overlapping contact between the resonance zone and the intermediate layer or the supporting layer or the first substrate, and the resonance zone is suspended relative to the cavity of the intermediate layer or the supporting layer or the first substrate, the difference in acoustic impedance between the resonance zone and the non-resonance zone can be increased, thereby improving the Q value of the resonance device.

[0048] The inventors of the present invention have also found that forming a piezoelectric layer on a plane can make the piezoelectric layer include no obvious turned crystals, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0049] The inventors of the present invention have also found that the use of the intermediate layer with a smaller acoustic impedance can prevent sound waves from leaking from the resonance area into the second substrate.

[0050] The inventors of the present invention have also found that disposing a thin film between the intermediate layer and the second substrate helps to prevent a free electron layer from being formed on the surface of the second substrate, thereby reducing the electrical loss caused by the second substrate.

[0051] An embodiment of the present invention provides a bulk acoustic wave resonance device, comprising: a first layer, the first layer comprising a first cavity located on a first side; a first electrode layer, a first end of the first electrode layer contacts the first layer, and a second end of the first electrode layer is located in the first cavity; a second layer, located on the first side and on the first electrode layer, the second layer is a flat layer, covering the first cavity; and a second electrode layer, located on the first side and on the second layer, wherein a first portion of the first electrode layer overlapping with the second electrode layer is located in the first cavity.

[0052] It should be noted that by adjusting the positions of the first electrode layer and the second electrode layer so that there is no overlapping contact between the resonance zone and the first layer, the resonance zone is suspended relative to the first cavity, which can increase the difference in acoustic impedance between the resonance zone and the non-resonance zone, thereby improving the Q value of the resonance device.

[0053] In some embodiments, the first layer further includes: an intermediate layer, the intermediate layer including the first cavity. In some embodiments, the material of the intermediate layer includes but is not limited to at least one of the following: a polymer, an insulating dielectric. In some embodiments, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), a photosensitive epoxy resin photoresist (e.g., SU-8), and a polyimide. In some embodiments, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, and titanium oxide. In some embodiments, the thickness of the intermediate layer includes but is not limited to: 0.1 microns to 10 microns.

[0054] In some embodiments, the first layer further includes: a support layer, the support layer including the first cavity. In some embodiments, the material of the support layer includes but is not limited to at least one of the following: a polymer, an insulating dielectric. In some embodiments, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), a photosensitive epoxy resin photoresist (e.g., SU-8), and polyimide. In some embodiments, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, and titanium oxide. In some embodiments, the thickness of the support layer includes but is not limited to: 20 microns to 100 microns.

[0055] In some embodiments, the first layer further comprises: a first substrate, the first substrate comprising the first cavity. In some embodiments, the material of the first substrate includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0056] In some embodiments, the first layer further includes: an etching shield layer, at least covering the bottom or sidewall of the first cavity. In some embodiments, the material of the etching shield layer includes but is not limited to at least one of the following: aluminum nitride, silicon carbide, diamond, silicon nitride, silicon dioxide, aluminum oxide, titanium dioxide. In some embodiments, the thickness of the etching shield layer includes but is not limited to: 0.1 micron to 3 microns. In some embodiments, the thickness of the etching shield layer includes but is not limited to: 2 microns to 6 microns.

[0057] It should be noted that the etching shielding layer can protect the intermediate layer or the supporting layer or the first substrate when the first cavity is formed by etching. In addition, the etching shielding layer can protect the resonance device from being corroded by water and oxygen.

[0058] In some embodiments, the first layer further includes a first groove located on the first side, the first groove is located on one side of the first cavity in the horizontal direction and communicates with the first cavity, and the first end is located in the first groove. It should be noted that the depth of the first groove is less than the depth of the first cavity, and the depth of the first groove at least corresponds to the thickness of the first electrode layer (for example, the depth of the first groove is equal to the thickness of the first electrode layer or the sum of the thickness of the first electrode layer and the thickness of the etching shield layer).

[0059] In some embodiments, the second layer includes: a piezoelectric layer, the piezoelectric layer includes a plurality of crystals, the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals; a first coordinate axis along the first direction corresponds to the height of the first crystal, and a second coordinate axis along the second direction corresponds to the height of the second crystal, wherein the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means: the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means: the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0060] In some embodiments, the first crystal corresponds to a first coordinate system, which includes the first coordinate axis and a third coordinate axis along a third direction; the second crystal corresponds to a second coordinate system, which includes the second coordinate axis and a fourth coordinate axis along a fourth direction.

[0061] In some embodiments, the first coordinate system further includes a fifth coordinate axis along a fifth direction, and the second coordinate system further includes a sixth coordinate axis along a sixth direction. In some embodiments, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0062] In some embodiments, the material of the piezoelectric layer includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0063] In some embodiments, the second layer includes: a piezoelectric layer, the piezoelectric layer includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to indicate the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the half-peak width (Full Width at Half Maximum, FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0064] It should be noted that forming the piezoelectric layer on a plane can prevent the piezoelectric layer from including crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0065] In some embodiments, a second portion of the second electrode layer overlapping with the first electrode layer is located above the first cavity, and a projection of the second portion perpendicular to the first layer is located within the first cavity.

[0066] In some embodiments, the material of the first electrode layer includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the second electrode layer includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0067] In some embodiments, the first electrode layer includes a first polarity, and the second electrode layer includes a second polarity. In some embodiments, the first electrode layer includes the first polarity and the second polarity, and the second electrode layer includes the first polarity and the second polarity. The first polarity and the second polarity are different. It should be noted that the electrode polarity includes positive and negative electrodes.

[0068] In some embodiments, the resonant device further comprises: a second substrate, located on a second side of the first layer, the second side being opposite to the first side. In some embodiments, the material of the second substrate includes but is not limited to at least one of the following: silicon, silicon carbide, and glass. It should be noted that the acoustic impedance of the first layer may be small, thereby preventing sound waves from leaking from the resonance region into the second substrate.

[0069] In some embodiments, the resonant device further comprises: a thin film located between the first layer and the second substrate. In some embodiments, the thin film includes but is not limited to: a polycrystalline thin film. In some embodiments, the material of the polycrystalline thin film includes but is not limited to at least one of the following: polycrystalline silicon, polycrystalline silicon nitride, polycrystalline silicon carbide.

[0070] It should be noted that the thin film helps to prevent a free electron layer from being formed on the surface of the second substrate, thereby reducing the electrical loss caused by the second substrate.

[0071] An embodiment of the present invention further provides a bulk acoustic wave filter device, comprising: a bulk acoustic wave resonance device provided by at least one of the above embodiments.

[0072] Figure 2 Schematic diagram of the cross-section A of a bulk acoustic wave resonance device 200 according to an embodiment of the present invention.

[0073] like Figure 2 As shown, the embodiment of the present invention provides a bulk acoustic wave resonator 200 including: a substrate 201, wherein the upper surface side of the substrate 201 includes a cavity 201a; an electrode layer 203, wherein the first end of the electrode layer 203 contacts the side wall of the cavity 201a, and the second end of the electrode layer 203 is located in the cavity 201a; a piezoelectric layer 205, which is located on the substrate 201 and the electrode layer 203, and the piezoelectric layer 205 is a flat layer, covering the cavity 201a; and an electrode layer 207, which is located on the piezoelectric layer 205. Figure 2 It can be seen that the resonance region 209 (i.e., the overlapping region of the electrode layer 203 and the electrode layer 207) is suspended relative to the cavity 201a and has no overlapping contact portion with the substrate 201. The vertical projection of the resonance region 209 perpendicular to the upper surface is located within the cavity 201a, which can increase the difference in acoustic impedance between the resonance region 209 and the non-resonance region, thereby improving the Q value of the resonance device.

[0074] In this embodiment, the material of the substrate 201 includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0075] In this embodiment, the piezoelectric layer 205 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 205 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0076] In this embodiment, the piezoelectric layer 205 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0077] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0078] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0079] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0080] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0081] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0082] In this embodiment, the piezoelectric layer 205 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0083] It should be noted that forming the piezoelectric layer 205 on a plane can make the piezoelectric layer 205 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0084] In this embodiment, the portion of the electrode layer 203 that overlaps with the electrode layer 207 is located in the cavity 201 a ; and the portion of the electrode layer 207 that overlaps with the electrode layer 203 is located above the cavity 201 a .

[0085] In this embodiment, the material of the electrode layer 203 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 207 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0086] In this embodiment, the electrode layer 203 includes a negative electrode, and the electrode layer 207 includes a positive electrode. In another embodiment, the electrode layer 203 includes a positive electrode, and the electrode layer 207 includes a negative electrode. In another embodiment, the electrode layer 203 includes a positive electrode and a negative electrode, and the electrode layer 207 includes a positive electrode and a negative electrode.

[0087] Figure 3 Schematic diagram of the cross-section A of a bulk acoustic wave resonance device 300 according to an embodiment of the present invention.

[0088] like Figure 3 As shown, an embodiment of the present invention provides a bulk acoustic wave resonance device 300 including: a substrate 301, wherein the upper surface side of the substrate 301 includes a cavity 301a and a groove 301b, wherein the groove 301b is located on one side of the cavity 301a in the horizontal direction and communicates with the cavity 301a, and the depth of the groove 301b is less than the depth of the cavity 301a; an electrode layer 303, wherein the first end of the electrode layer 303 is located in the groove 301b, and the second end of the electrode layer 303 is located in the cavity 301a, wherein the depth of the groove 301b is equal to the thickness of the electrode 303; a piezoelectric layer 305, located on the substrate 301 and the electrode layer 303, the piezoelectric layer 305 is a flat layer, covering the cavity 301a; and an electrode layer 307, located on the piezoelectric layer 305. Figure 3 It can be seen that the resonance region 309 (i.e., the overlapping region of the electrode layer 303 and the electrode layer 307) is suspended relative to the cavity 301a, and has no overlapping contact portion with the substrate 301. The vertical projection of the resonance region 309 perpendicular to the upper surface is located within the cavity 301a, which can increase the difference in acoustic impedance between the resonance region 309 and the non-resonance region, thereby improving the Q value of the resonance device.

[0089] In this embodiment, the material of the substrate 301 includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0090] In this embodiment, the piezoelectric layer 305 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 305 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0091] In this embodiment, the piezoelectric layer 305 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0092] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0093] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0094] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0095] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0096] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0097] In this embodiment, the piezoelectric layer 305 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to indicate the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function values ​​before and after a peak are equal to half of the peak value.

[0098] It should be noted that forming the piezoelectric layer 305 on a plane can make the piezoelectric layer 305 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0099] In this embodiment, the portion of the electrode layer 303 that overlaps with the electrode layer 307 is located in the cavity 301 a ; and the portion of the electrode layer 307 that overlaps with the electrode layer 303 is located above the cavity 301 a .

[0100] In this embodiment, the material of the electrode layer 303 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 307 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0101] In this embodiment, the electrode layer 303 includes a negative electrode, and the electrode layer 307 includes a positive electrode. In another embodiment, the electrode layer 303 includes a positive electrode, and the electrode layer 307 includes a negative electrode. In another embodiment, the electrode layer 303 includes a positive electrode and a negative electrode, and the electrode layer 307 includes a positive electrode and a negative electrode.

[0102] Figure 4 4 is a schematic diagram of the cross-section A of a bulk acoustic wave resonance device 400 according to an embodiment of the present invention.

[0103] like Figure 4 As shown, the embodiment of the present invention provides a bulk acoustic wave resonator 400 including: a substrate 401, wherein the upper surface side of the substrate 401 includes a cavity 401a; an etching shielding layer 411, located in the cavity 401a, covering the bottom and sidewalls of the cavity 401a; an electrode layer 403, wherein the first end of the electrode layer 403 contacts the etching shielding layer 411, and the second end of the electrode layer 403 is located in the cavity 401a; a piezoelectric layer 405, located on the substrate 401 and the electrode layer 403, wherein the piezoelectric layer 405 is a flat layer, covering the cavity 401a; and an electrode layer 407, located on the piezoelectric layer 405. Figure 4 It can be seen that the resonance region 409 (i.e., the overlapping region of the electrode layer 403 and the electrode layer 407) is suspended relative to the cavity 401a, and has no overlapping contact portion with the substrate 401. The vertical projection of the resonance region 409 perpendicular to the upper surface is located within the cavity 401a, which can increase the difference in acoustic impedance between the resonance region 409 and the non-resonance region, thereby improving the Q value of the resonance device.

[0104] In this embodiment, the material of the substrate 401 includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0105] In this embodiment, the material of the etching shielding layer 411 includes but is not limited to at least one of the following: aluminum nitride, silicon carbide, diamond, silicon nitride, silicon dioxide, aluminum oxide, and titanium dioxide.

[0106] It should be noted that the etching shielding layer 411 can protect the substrate 401 when the cavity 401a is formed by etching. In addition, the etching shielding layer 411 can protect the resonance device from being corroded by water and oxygen.

[0107] In this embodiment, the thickness of the etching shielding layer 411 includes, but is not limited to, 0.1 micrometer to 3 micrometers. In another embodiment, the thickness of the etching shielding layer 411 includes, but is not limited to, 2 micrometers to 6 micrometers.

[0108] In this embodiment, the piezoelectric layer 405 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 405 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0109] In this embodiment, the piezoelectric layer 405 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0110] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0111] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0112] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0113] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0114] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0115] In this embodiment, the piezoelectric layer 405 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0116] It should be noted that forming the piezoelectric layer 405 on a plane can make the piezoelectric layer 405 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0117] In this embodiment, the portion of the electrode layer 403 that overlaps with the electrode layer 407 is located in the cavity 401 a ; and the portion of the electrode layer 407 that overlaps with the electrode layer 403 is located above the cavity 401 a .

[0118] In this embodiment, the material of the electrode layer 403 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 407 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0119] In this embodiment, the electrode layer 403 includes a negative electrode, and the electrode layer 407 includes a positive electrode. In another embodiment of the present invention, the electrode layer 403 includes a positive electrode, and the electrode layer 407 includes a negative electrode. In another embodiment of the present invention, the electrode layer 403 includes a positive electrode and a negative electrode, and the electrode layer 407 includes a positive electrode and a negative electrode.

[0120] Figure 5 Schematic diagram of the cross-section A of a bulk acoustic wave resonance device 500 according to an embodiment of the present invention.

[0121] like Figure 5 As shown, the embodiment of the present invention provides a bulk acoustic wave resonator 500 including: a substrate 501; an intermediate layer 502, located on the substrate 501, the upper surface side of the intermediate layer 502 includes a cavity 502a; an electrode layer 503, the first end of the electrode layer 503 contacts the side wall of the cavity 502a, and the second end of the electrode layer 503 is located in the cavity 502a; a piezoelectric layer 505, located on the intermediate layer 502 and the electrode layer 503, the piezoelectric layer 505 is a flat layer, covering the cavity 502a; an electrode layer 507, located on the piezoelectric layer 505. Figure 5 It can be seen that the resonance zone (not shown, i.e., the overlapping area of ​​the electrode layer 503 and the electrode layer 507) is suspended relative to the cavity 502a and has no overlapping contact portion with the intermediate layer 502, so that the vertical projection of the resonance zone (not shown) perpendicular to the upper surface is located within the cavity 502a.

[0122] The embodiment of the present invention can improve the difference between the acoustic impedance of the resonant region (not shown) and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the acoustic impedance of the intermediate layer 502 can be small, thereby blocking sound waves from leaking from the resonant region (not shown) into the substrate 501.

[0123] In this embodiment, the material of the substrate 501 includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0124] In this embodiment, the material of the intermediate layer 502 includes but is not limited to at least one of the following: polymer, insulating dielectric. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0125] In this embodiment, the thickness of the intermediate layer 502 includes but is not limited to: 0.1 micrometer to 10 micrometers.

[0126] In this embodiment, the piezoelectric layer 505 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 505 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0127] In this embodiment, the piezoelectric layer 505 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0128] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0129] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0130] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0131] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0132] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0133] In this embodiment, the piezoelectric layer 505 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0134] It should be noted that forming the piezoelectric layer 505 on a plane can make the piezoelectric layer 505 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0135] In this embodiment, the portion of the electrode layer 503 that overlaps with the electrode layer 507 is located in the cavity 502a; and the portion of the electrode layer 507 that overlaps with the electrode layer 503 is located above the cavity 502a.

[0136] In this embodiment, the material of the electrode layer 503 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 507 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0137] In this embodiment, the electrode layer 503 includes a negative electrode, and the electrode layer 507 includes a positive electrode. In another embodiment, the electrode layer 503 includes a positive electrode, and the electrode layer 507 includes a negative electrode. In another embodiment, the electrode layer 503 includes a positive electrode and a negative electrode, and the electrode layer 507 includes a positive electrode and a negative electrode.

[0138] Figure 6 Schematic diagram of the cross-section A of a bulk acoustic wave resonance device 600 according to an embodiment of the present invention.

[0139] like Figure 6As shown, the embodiment of the present invention provides a bulk acoustic wave resonance device 600 including: a substrate 601; an intermediate layer 602, located on the substrate 601, the upper surface side of the intermediate layer 602 including a cavity 602a and a groove 602b, wherein the groove 602b is located on one side of the cavity 602a in the horizontal direction and communicates with the cavity 602a, and the depth of the groove 602b is less than the depth of the cavity 602a; an electrode layer 603, the first end of the electrode layer 603 is located in the groove 602b, and the second end of the electrode layer 603 is located in the cavity 602a, wherein the depth of the groove 602b is equal to the thickness of the electrode 603; a piezoelectric layer 605, located on the intermediate layer 602 and the electrode layer 603, the piezoelectric layer 605 is a flat layer, covering the cavity 602a; an electrode layer 607, located on the piezoelectric layer 605. Figure 6 It can be seen that the resonance zone (not shown, i.e., the overlapping area of ​​the electrode layer 603 and the electrode layer 607) is suspended relative to the cavity 602a and has no overlapping contact portion with the intermediate layer 602, so that the vertical projection of the resonance zone (not shown) perpendicular to the upper surface is located within the cavity 602a.

[0140] The embodiment of the present invention can improve the difference between the acoustic impedance of the resonant region (not shown) and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the acoustic impedance of the intermediate layer 602 can be small, thereby preventing sound waves from leaking from the resonant region (not shown) into the substrate 601.

[0141] In this embodiment, the material of the substrate 601 includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0142] In this embodiment, the material of the intermediate layer 602 includes but is not limited to at least one of the following: polymer, insulating dielectric. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0143] In this embodiment, the thickness of the intermediate layer 602 includes but is not limited to: 0.1 micrometer to 10 micrometers.

[0144] In this embodiment, the piezoelectric layer 605 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 605 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0145] In this embodiment, the piezoelectric layer 605 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0146] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0147] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0148] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0149] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0150] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0151] In this embodiment, the piezoelectric layer 605 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0152] It should be noted that forming the piezoelectric layer 605 on a plane can make the piezoelectric layer 605 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0153] In this embodiment, the portion of the electrode layer 603 that overlaps with the electrode layer 607 is located in the cavity 602a; and the portion of the electrode layer 607 that overlaps with the electrode layer 603 is located above the cavity 602a.

[0154] In this embodiment, the material of the electrode layer 603 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 607 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0155] In this embodiment, the electrode layer 603 includes a negative electrode, and the electrode layer 607 includes a positive electrode. In another embodiment, the electrode layer 603 includes a positive electrode, and the electrode layer 607 includes a negative electrode. In another embodiment, the electrode layer 603 includes a positive electrode and a negative electrode, and the electrode layer 607 includes a positive electrode and a negative electrode.

[0156] Figure 7 Schematic diagram of the cross-section A of a bulk acoustic wave resonance device 700 according to an embodiment of the present invention.

[0157] like Figure 7 As shown, an embodiment of the present invention provides a bulk acoustic wave resonance device 700 including: a substrate 701; an intermediate layer 702, located on the substrate 701, the upper surface side of the intermediate layer 702 including a cavity 702a and a groove 702b, wherein the groove 702b is located on one side of the cavity 702a in the horizontal direction and communicates with the cavity 702a, and the depth of the groove 702b is less than the depth of the cavity 702a; an etching shielding layer 711, covering the bottom and side walls of the cavity 702a, the bottom and side walls of the groove 702b, and the upper surface side of the intermediate layer 702; an electrode layer 703, wherein the first end of the electrode layer 703 is located in the groove 702b, and the second end of the electrode layer 703 is located in the cavity 702a, wherein the depth of the groove 702b is equal to the sum of the thickness of the etching shield layer 711 and the thickness of the electrode layer 703; a piezoelectric layer 705, located on the etching shield layer 711 and the electrode layer 703, the piezoelectric layer 705 is a flat layer, covering the cavity 702a; and an electrode layer 707, located on the piezoelectric layer 705. Figure 7 It can be seen that the resonance zone (not shown, i.e., the overlapping area of ​​the electrode layer 703 and the electrode layer 707) is suspended relative to the cavity 702a, and has no overlapping contact with the intermediate layer 702 and the etching shielding layer 711, so that the vertical projection of the resonance zone (not shown) perpendicular to the upper surface is located within the cavity 702a.

[0158] The embodiment of the present invention can improve the difference between the acoustic impedance of the resonant region (not shown) and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the acoustic impedance of the intermediate layer 702 can be small, thereby preventing sound waves from leaking from the resonant region (not shown) into the substrate 701.

[0159] In this embodiment, the material of the substrate 701 includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0160] In this embodiment, the material of the intermediate layer 702 includes but is not limited to at least one of the following: polymer, insulating dielectric. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0161] In this embodiment, the thickness of the intermediate layer 702 includes but is not limited to: 0.1 micrometer to 10 micrometers.

[0162] In this embodiment, the material of the etching shielding layer 711 includes but is not limited to at least one of the following: aluminum nitride, silicon carbide, diamond, silicon nitride, silicon dioxide, aluminum oxide, and titanium dioxide.

[0163] It should be noted that the etching shielding layer 711 can protect the intermediate layer 702 when the cavity 702a is formed by etching. In addition, the etching shielding layer 711 can protect the resonance device from being corroded by water and oxygen.

[0164] In this embodiment, the thickness of the etching shielding layer 711 includes but is not limited to: 0.1 micrometer to 3 micrometers.

[0165] In this embodiment, the piezoelectric layer 705 also covers the etching shielding layer 711. In this embodiment, the material of the piezoelectric layer 705 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0166] In this embodiment, the piezoelectric layer 705 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0167] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0168] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0169] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0170] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0171] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0172] In this embodiment, the piezoelectric layer 705 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0173] It should be noted that forming the piezoelectric layer 705 on a plane can make the piezoelectric layer 705 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0174] In this embodiment, the portion of the electrode layer 703 that overlaps with the electrode layer 707 is located in the cavity 702a; and the portion of the electrode layer 707 that overlaps with the electrode layer 703 is located above the cavity 702a.

[0175] In this embodiment, the material of the electrode layer 703 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 707 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0176] In this embodiment, the electrode layer 703 includes a negative electrode, and the electrode layer 707 includes a positive electrode. In another embodiment, the electrode layer 703 includes a positive electrode, and the electrode layer 707 includes a negative electrode. In another embodiment, the electrode layer 703 includes a positive electrode and a negative electrode, and the electrode layer 707 includes a positive electrode and a negative electrode.

[0177] Figure 8 Schematic diagram of the cross-section A of a bulk acoustic wave resonance device 800 according to an embodiment of the present invention.

[0178] like Figure 8 As shown, the embodiment of the present invention provides a bulk acoustic wave resonator 800 including: a support layer 802, the upper surface side of the support layer 802 includes a cavity 802a; an electrode layer 803, the first end of the electrode layer 803 contacts the side wall of the cavity 802a, and the second end of the electrode layer 803 is located in the cavity 802a; a piezoelectric layer 805, located on the support layer 802 and the electrode layer 803, the piezoelectric layer 805 is a flat layer, covering the cavity 802a; an electrode layer 807, located on the piezoelectric layer 805. Figure 8 It can be seen that the resonance zone (not shown, i.e., the overlapping area of ​​the electrode layer 803 and the electrode layer 807) is suspended relative to the cavity 802a and has no overlapping contact portion with the support layer 802, so that the vertical projection of the resonance zone (not shown) perpendicular to the upper surface is located within the cavity 802a.

[0179] The embodiment of the present invention can improve the difference in acoustic impedance between the resonant region (not shown) and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the resonant device 800 provided by the embodiment of the present invention does not include a substrate, thereby eliminating electrical losses caused by the substrate.

[0180] In this embodiment, the material of the support layer 802 includes but is not limited to at least one of the following: polymer, insulating dielectric. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0181] In this embodiment, the thickness of the support layer 802 includes but is not limited to: 20 microns to 100 microns.

[0182] In this embodiment, the piezoelectric layer 805 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 805 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0183] In this embodiment, the piezoelectric layer 805 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0184] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0185] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0186] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0187] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0188] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0189] In this embodiment, the piezoelectric layer 805 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0190] It should be noted that forming the piezoelectric layer 805 on a plane can make the piezoelectric layer 805 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0191] In this embodiment, the portion of the electrode layer 803 that overlaps with the electrode layer 807 is located in the cavity 802a; and the portion of the electrode layer 807 that overlaps with the electrode layer 803 is located above the cavity 802a.

[0192] In this embodiment, the material of the electrode layer 803 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 807 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0193] In this embodiment, the electrode layer 803 includes a negative electrode, and the electrode layer 807 includes a positive electrode. In another embodiment, the electrode layer 803 includes a positive electrode, and the electrode layer 807 includes a negative electrode. In another embodiment, the electrode layer 803 includes a positive electrode and a negative electrode, and the electrode layer 807 includes a positive electrode and a negative electrode.

[0194] Fig. 9 1 is a schematic structural diagram of a cross-section A of a bulk acoustic wave resonance device 900 according to an embodiment of the present invention.

[0195] like Fig. 9 As shown, an embodiment of the present invention provides a bulk acoustic wave resonance device 900 including: a support layer 902, wherein the upper surface side of the support layer 902 includes a cavity 902a and a groove 902b, wherein the groove 902b is located on one side of the cavity 902a in the horizontal direction and communicates with the cavity 902a, and the depth of the groove 902b is less than the depth of the cavity 902a; an electrode layer 903, wherein the first end of the electrode layer 903 is located in the groove 902b, and the second end of the electrode layer 903 is located in the cavity 902a, wherein the depth of the groove 902b is equal to the thickness of the electrode layer 903; a piezoelectric layer 905, located on the support layer 902 and the electrode layer 903, the piezoelectric layer 905 is a flat layer, covering the cavity 902a; and an electrode layer 907, located on the piezoelectric layer 905. Fig. 9 It can be seen that the resonance zone (not shown, i.e., the overlapping area of ​​the electrode layer 903 and the electrode layer 907) is suspended relative to the cavity 902a and has no overlapping contact portion with the support layer 902, so that the vertical projection of the resonance zone (not shown) perpendicular to the upper surface is located within the cavity 902a.

[0196] The embodiment of the present invention can improve the difference in acoustic impedance between the resonant region (not shown) and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the resonant device 900 provided by the embodiment of the present invention does not include a substrate, thereby eliminating electrical losses caused by the substrate.

[0197] In this embodiment, the material of the support layer 902 includes but is not limited to at least one of the following: polymer, insulating dielectric. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0198] In this embodiment, the thickness of the support layer 902 includes but is not limited to: 20 micrometers to 100 micrometers.

[0199] In this embodiment, the piezoelectric layer 905 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 905 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0200] In this embodiment, the piezoelectric layer 905 includes a plurality of crystals, the plurality of crystals including a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0201] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0202] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0203] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0204] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0205] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0206] In this embodiment, the piezoelectric layer 905 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0207] It should be noted that forming the piezoelectric layer 905 on a plane can make the piezoelectric layer 905 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0208] In this embodiment, the portion of the electrode layer 903 that overlaps with the electrode layer 907 is located in the cavity 902a; and the portion of the electrode layer 907 that overlaps with the electrode layer 903 is located above the cavity 902a.

[0209] In this embodiment, the material of the electrode layer 903 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 907 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0210] In this embodiment, the electrode layer 903 includes a negative electrode, and the electrode layer 907 includes a positive electrode. In another embodiment, the electrode layer 903 includes a positive electrode, and the electrode layer 907 includes a negative electrode. In another embodiment, the electrode layer 903 includes a positive electrode and a negative electrode, and the electrode layer 907 includes a positive electrode and a negative electrode.

[0211] Fig.10 1 is a schematic diagram of the cross-section A of a bulk acoustic wave resonance device 1000 according to an embodiment of the present invention.

[0212] like Fig.10As shown, the embodiment of the present invention provides a bulk acoustic wave resonance device 1000 including: a support layer 1002, wherein the upper surface side of the support layer 1002 includes a cavity 1002a and a groove 1002b, wherein the groove 1002b is located on one side of the cavity 1002a in the horizontal direction and communicates with the cavity 1002a, and the depth of the groove 1002b is less than the depth of the cavity 1002a; an etching shielding layer 1011, covering the bottom and side walls of the cavity 1002a, the bottom and side walls of the groove 1002b, and the support layer 100 2; an electrode layer 1003, wherein the first end of the electrode layer 1003 is located in the groove 1002b, and the second end of the electrode layer 1003 is located in the cavity 1002a, wherein the depth of the groove 1002b is equal to the sum of the thickness of the etching shield layer 1011 and the thickness of the electrode layer 1003; a piezoelectric layer 1005, located on the etching shield layer 1011 and the electrode layer 1003, the piezoelectric layer 1005 is a flat layer, covering the cavity 1002a; an electrode layer 1007, located on the piezoelectric layer 1005. Fig.10 It can be seen that the resonance zone (not shown, i.e., the overlapping area of ​​the electrode layer 1003 and the electrode layer 1007) is suspended relative to the cavity 1002a, and has no overlapping contact with the support layer 1002 and the corresponding etching shielding layer 1011, so that the vertical projection of the resonance zone (not shown) perpendicular to the upper surface is located within the cavity 1002a.

[0213] The embodiment of the present invention can improve the difference in acoustic impedance between the resonant region (not shown) and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the resonant device 1000 provided by the embodiment of the present invention does not include a substrate, thereby eliminating electrical losses caused by the substrate.

[0214] In this embodiment, the material of the support layer 1002 includes but is not limited to at least one of the following: polymer, insulating dielectric. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0215] In this embodiment, the thickness of the support layer 1002 includes but is not limited to: 20 microns to 100 microns.

[0216] In this embodiment, the material of the etching shielding layer 1011 includes but is not limited to at least one of the following: aluminum nitride, silicon carbide, diamond, silicon nitride, silicon dioxide, aluminum oxide, and titanium dioxide.

[0217] It should be noted that the etching shielding layer 1011 can protect the supporting layer 1002 when the cavity 1002a is formed by etching. In addition, the etching shielding layer 1011 can protect the resonance device from being corroded by water and oxygen.

[0218] In this embodiment, the thickness of the etching shielding layer 1011 includes but is not limited to: 2 microns to 6 microns.

[0219] In this embodiment, the piezoelectric layer 1005 also covers the etching shielding layer 1011. In this embodiment, the material of the piezoelectric layer 1005 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0220] In this embodiment, the piezoelectric layer 1005 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0221] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0222] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0223] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0224] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0225] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0226] In this embodiment, the piezoelectric layer 1005 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0227] It should be noted that forming the piezoelectric layer 1005 on a plane can make the piezoelectric layer 1005 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0228] In this embodiment, the portion of the electrode layer 1003 that overlaps with the electrode layer 1007 is located in the cavity 1002a; and the portion of the electrode layer 1007 that overlaps with the electrode layer 1003 is located above the cavity 1002a.

[0229] In this embodiment, the material of the electrode layer 1003 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 1007 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0230] In this embodiment, the electrode layer 1003 includes a negative electrode, and the electrode layer 1007 includes a positive electrode. In another embodiment, the electrode layer 1003 includes a positive electrode, and the electrode layer 1007 includes a negative electrode. In another embodiment, the electrode layer 1003 includes a positive electrode and a negative electrode, and the electrode layer 1007 includes a positive electrode and a negative electrode.

[0231] Fig.11 1 is a schematic diagram of the cross-section A of a bulk acoustic wave resonator device 1100 according to an embodiment of the present invention.

[0232] like Fig.11 As shown, the embodiment of the present invention provides a bulk acoustic wave resonance device 1100 including: a substrate 1101; a thin film 1104, located on the substrate 1101; an intermediate layer 1102, located on the thin film 1104, the upper surface side of the intermediate layer 1102 includes a cavity 1102a; an electrode layer 1103, the first end of the electrode layer 1103 contacts the side wall of the cavity 1102a, and the second end of the electrode layer 1103 is located in the cavity 1102a; a piezoelectric layer 1105, located on the intermediate layer 1102 and the electrode layer 1103, the piezoelectric layer 1105 is a flat layer, covering the cavity 1102a; an electrode layer 1107, located on the piezoelectric layer 1105. Fig.11 It can be seen that the resonance zone (not shown, i.e., the overlapping area of ​​the electrode layer 1103 and the electrode layer 1107) is suspended relative to the cavity 1102a and has no overlapping contact portion with the intermediate layer 1102, so that the vertical projection of the resonance zone (not shown) perpendicular to the upper surface is located within the cavity 1102a.

[0233] The embodiment of the present invention can improve the difference between the acoustic impedance of the resonant region (not shown) and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the acoustic impedance of the intermediate layer 1102 can be small, thereby blocking the sound waves from leaking from the resonant region (not shown) into the substrate 1101. In addition, the film 1104 helps to prevent the formation of a free electron layer on the surface of the substrate 1101, so as to reduce the electrical loss caused by the substrate 1101.

[0234] In this embodiment, the material of the substrate 1101 includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0235] In this embodiment, the film 1104 includes but is not limited to a polycrystalline film. In this embodiment, the material of the polycrystalline film includes but is not limited to at least one of the following: polycrystalline silicon, polycrystalline silicon nitride, and polycrystalline silicon carbide.

[0236] In this embodiment, the material of the intermediate layer 1102 includes but is not limited to at least one of the following: polymer, insulating dielectric. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0237] In this embodiment, the thickness of the intermediate layer 1102 includes but is not limited to: 0.1 micrometer to 10 micrometers.

[0238] In this embodiment, the piezoelectric layer 1105 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 1105 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0239] In this embodiment, the piezoelectric layer 1105 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0240] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0241] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0242] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0243] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0244] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0245] In this embodiment, the piezoelectric layer 1105 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function value is equal to half of the peak value in a peak of the function.

[0246] It should be noted that forming the piezoelectric layer 1105 on a plane can make the piezoelectric layer 1105 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0247] In this embodiment, the portion of the electrode layer 1103 that overlaps with the electrode layer 1107 is located in the cavity 1102a; and the portion of the electrode layer 1107 that overlaps with the electrode layer 1103 is located above the cavity 1102a.

[0248] In this embodiment, the material of the electrode layer 1103 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 1107 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0249] In this embodiment, the electrode layer 1103 includes a negative electrode, and the electrode layer 1107 includes a positive electrode. In another embodiment, the electrode layer 1103 includes a positive electrode, and the electrode layer 1107 includes a negative electrode. In another embodiment, the electrode layer 1103 includes a positive electrode and a negative electrode, and the electrode layer 1107 includes a positive electrode and a negative electrode.

[0250] Fig.12 1 is a schematic diagram of the cross-section A of a bulk acoustic wave resonance device 1200 according to an embodiment of the present invention.

[0251] like Fig.12 As shown, the embodiment of the present invention provides a bulk acoustic wave resonance device 1200 including: a substrate 1201; a thin film 1204, located on the substrate 1201; an intermediate layer 1202, located on the thin film 1204, the upper surface side of the intermediate layer 1202 includes a cavity 1202a and a groove 1202b, wherein the groove 1202b is located on one side of the cavity 1202a in the horizontal direction and communicates with the cavity 1202a, and the depth of the groove 1202b is less than the depth of the cavity 1202 a; electrode layer 1203, the first end of the electrode layer 1203 is located in the groove 1202b, and the second end of the electrode layer 1203 is located in the cavity 1202a, wherein the depth of the groove 1202b is equal to the thickness of the electrode layer 1203; piezoelectric layer 1205, located on the intermediate layer 1202 and the electrode layer 1203, the piezoelectric layer 1205 is a flat layer, covering the cavity 1202a; electrode layer 1207, located on the piezoelectric layer 1205. Fig.12 It can be seen that the resonance zone (not shown, i.e., the overlapping area of ​​the electrode layer 1203 and the electrode layer 1207) is suspended relative to the cavity 1202a and has no overlapping contact portion with the intermediate layer 1202, so that the vertical projection of the resonance zone (not shown) perpendicular to the upper surface is located within the cavity 1202a.

[0252] The embodiment of the present invention can improve the difference between the acoustic impedance of the resonant region (not shown) and the non-resonant region, thereby improving the Q value of the resonant device. In addition, the acoustic impedance of the intermediate layer 1202 can be small, thereby blocking the sound waves from leaking from the resonant region (not shown) into the substrate 1201. In addition, the film 1204 helps to prevent the formation of a free electron layer on the surface of the substrate 1201, so as to reduce the electrical loss caused by the substrate 1201.

[0253] In this embodiment, the material of the substrate 1201 includes but is not limited to at least one of the following: silicon, silicon carbide, and glass.

[0254] In this embodiment, the film 1204 includes but is not limited to a polycrystalline film. In this embodiment, the material of the polycrystalline film includes but is not limited to at least one of the following: polycrystalline silicon, polycrystalline silicon nitride, and polycrystalline silicon carbide.

[0255] In this embodiment, the material of the intermediate layer 1202 includes but is not limited to at least one of the following: polymer, insulating dielectric. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0256] In this embodiment, the thickness of the intermediate layer 1202 includes but is not limited to: 0.1 micrometer to 10 micrometers.

[0257] In this embodiment, the piezoelectric layer 1205 also covers the upper surface side. In this embodiment, the material of the piezoelectric layer 1205 includes but is not limited to at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0258] In this embodiment, the piezoelectric layer 1205 includes a plurality of crystals, and the plurality of crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals of the plurality of crystals. A person skilled in the art knows that the crystal orientation, crystal plane, etc. of a crystal can be represented based on a coordinate system. Fig.13 As shown in FIG. 1 , for a hexagonal crystal, such as aluminum nitride crystal, an ac stereo coordinate system (including an a-axis and a c-axis) is used to represent it. Fig.14 As shown, for crystals of (i) orthorhombic system (a≠b≠c), (ii) tetragonal system (a=b≠c), (iii) cubic system (a=b=c), etc., an xyz three-dimensional coordinate system (including x-axis, y-axis and z-axis) is used for representation. In addition to the above two examples, crystals can also be represented based on other coordinate systems known to those skilled in the art, so the present invention is not limited to the above two examples.

[0259] In this embodiment, the first crystal can be represented based on a first three-dimensional coordinate system, and the second crystal can be represented based on a second three-dimensional coordinate system, wherein the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, wherein the first coordinate axis corresponds to the height of the first crystal, and the second coordinate axis corresponds to the height of the second crystal.

[0260] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same means that the angle between the vector along the first direction and the vector along the second direction ranges from 0 degrees to 5 degrees; the first direction and the second direction are opposite means that the angle between the vector along the first direction and the vector along the second direction ranges from 175 degrees to 180 degrees.

[0261] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, wherein the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, wherein the first c-axis and the second c-axis point in the same or opposite directions.

[0262] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction is the same as or opposite to the second direction, and the third direction is the same as or opposite to the fourth direction. It should be noted that the third direction is the same as the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 0 degrees to 5 degrees; the third direction is opposite to the fourth direction, which means that the angle between the vector along the third direction and the vector along the fourth direction ranges from 175 degrees to 180 degrees.

[0263] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0264] In this embodiment, the piezoelectric layer 1205 includes a plurality of crystals, and the half-peak width of the rocking curve of the crystal composed of the plurality of crystals is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a certain crystal plane (the crystal plane determined by the diffraction angle) in the sample, and is represented by a plane coordinate system, wherein the horizontal axis is the angle between the crystal plane and the sample plane, and the vertical axis represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the quality of the crystal, and the smaller the half-peak width angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between the two points where the function values ​​before and after a peak are equal to half of the peak value.

[0265] It should be noted that forming the piezoelectric layer 1205 on a plane can make the piezoelectric layer 1205 not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0266] In this embodiment, the portion of the electrode layer 1203 that overlaps with the electrode layer 1207 is located in the cavity 1202a; and the portion of the electrode layer 1207 that overlaps with the electrode layer 1203 is located above the cavity 1202a.

[0267] In this embodiment, the material of the electrode layer 1203 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the electrode layer 1207 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

[0268] In this embodiment, the electrode layer 1203 includes a negative electrode, and the electrode layer 1207 includes a positive electrode. In another embodiment, the electrode layer 1203 includes a positive electrode, and the electrode layer 1207 includes a negative electrode. In another embodiment, the electrode layer 1203 includes a positive electrode and a negative electrode, and the electrode layer 1207 includes a positive electrode and a negative electrode.

[0269] An embodiment of the present invention further provides a bulk acoustic wave filter device, including but not limited to: a bulk acoustic wave resonance device provided by at least one of the above embodiments.

[0270] In summary, the present invention adjusts the positions of the two electrode layers so that there is no overlapping contact between the resonance zone and the intermediate layer or the supporting layer or the first substrate, and the resonance zone is suspended relative to the cavity of the intermediate layer or the supporting layer or the first substrate, which can enhance the difference in acoustic impedance between the resonance zone and the non-resonance zone, thereby improving the Q value of the resonance device. In addition, forming a piezoelectric layer on a plane can make the piezoelectric layer not include crystals with obvious turning, thereby helping to improve the electromechanical coupling coefficient of the resonance device and the Q value of the resonance device. In addition, the use of the intermediate layer with a smaller acoustic impedance can prevent sound waves from leaking from the resonance zone into the second substrate. In addition, the provision of a thin film between the intermediate layer and the second substrate helps prevent the formation of a free electron layer on the surface of the second substrate, thereby reducing the electrical loss caused by the second substrate.

[0271] It should be understood that the examples and embodiments herein are merely illustrative and that various modifications and corrections may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined in this application and the appended claims.

Claims

1. A bulk acoustic wave resonance device, characterized in that: include: a first layer, the first layer comprising a first cavity on a first side; a first electrode layer, wherein a first end of the first electrode layer contacts the first layer, and a second end of the first electrode layer is located in the first cavity; a second layer, located on the first side and on the first electrode layer, wherein the second layer is a flat layer and covers the first cavity; as well as a second electrode layer, located on the first side and on the second layer; Wherein, a first portion of the first electrode layer overlapping with the second electrode layer is located in the first cavity; The second layer includes: a piezoelectric layer, the piezoelectric layer includes multiple crystals, the multiple crystals include a first crystal and a second crystal, wherein the first crystal and the second crystal are any two crystals among the multiple crystals; a first coordinate axis along the first direction corresponds to the height of the first crystal, and a second coordinate axis along the second direction corresponds to the height of the second crystal, wherein the first direction and the second direction are the same or opposite.

2. The bulk acoustic wave resonator device according to claim 1, characterized in that: The first layer further includes: an intermediate layer, and the intermediate layer includes the first cavity.

3. The bulk acoustic wave resonator device according to claim 2, characterized in that: The material of the intermediate layer includes at least one of the following: polymer, insulating dielectric.

4. The bulk acoustic wave resonator device according to claim 3, characterized in that: The polymer includes at least one of the following: benzocyclobutene, photosensitive epoxy resin photoresist, and polyimide.

5. The bulk acoustic wave resonator device according to claim 3, characterized in that: The insulating dielectric includes at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, and titanium oxide.

6. The bulk acoustic wave resonator device according to claim 2, characterized in that: The thickness of the intermediate layer is in a range of 0.1 micrometers to 10 micrometers.

7. The bulk acoustic wave resonator device according to claim 1, characterized in that: The first layer further includes: a supporting layer, wherein the supporting layer includes the first cavity.

8. The bulk acoustic wave resonator device according to claim 7, characterized in that: The material of the support layer includes at least one of the following: polymer, insulating dielectric.

9. The bulk acoustic wave resonator device according to claim 8, characterized in that: The polymer includes at least one of the following: benzocyclobutene, photosensitive epoxy resin photoresist, and polyimide.

10. The bulk acoustic wave resonator device according to claim 8, characterized in that: The insulating dielectric includes at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, and titanium oxide.

11. The bulk acoustic wave resonator device according to claim 7, characterized in that: The thickness of the support layer is in a range of 20 micrometers to 100 micrometers.

12. The bulk acoustic wave resonator device according to claim 1, characterized in that: The first layer further includes: a first substrate, wherein the first substrate includes the first cavity.

13. The bulk acoustic wave resonator device according to claim 12, characterized in that: The material of the first substrate includes at least one of the following: silicon, silicon carbide, and glass.

14. The bulk acoustic wave resonator device according to claim 1, characterized in that: The first layer further includes: an etching shielding layer, which at least covers the bottom or sidewall of the first cavity.

15. The bulk acoustic wave resonator device according to claim 14, characterized in that: The material of the etching shielding layer includes at least one of the following: aluminum nitride, silicon carbide, diamond, silicon nitride, silicon dioxide, aluminum oxide, and titanium dioxide.

16. The bulk acoustic wave resonator device according to claim 14, characterized in that: The thickness of the etching shielding layer ranges from 0.1 micrometer to 3 micrometers.

17. The bulk acoustic wave resonator device according to claim 14, characterized in that: The thickness of the etching shielding layer ranges from 2 microns to 6 microns.

18. The bulk acoustic wave resonator device according to claim 1, characterized in that: The first layer further includes a first groove located on the first side, the first groove is located on one side of the first cavity in a horizontal direction and communicates with the first cavity, and the first end is located in the first groove.

19. The BAW resonator device according to claim 1, characterized in that: The first crystal corresponds to a first coordinate system, which includes the first coordinate axis and a third coordinate axis along a third direction; the second crystal corresponds to a second coordinate system, which includes the second coordinate axis and a fourth coordinate axis along a fourth direction.

20. The BAW resonator device according to claim 19, characterized in that: The first coordinate system further includes a fifth coordinate axis along a fifth direction, and the second coordinate system further includes a sixth coordinate axis along a sixth direction.

21. The BAW resonator device according to claim 20, characterized in that: The third direction is the same as or opposite to the fourth direction.

22. The BAW resonator device according to claim 1, characterized in that: The material of the piezoelectric layer includes at least one of the following: aluminum nitride, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, and lead magnesium niobate-lead titanate.

23. The BAW resonator device according to claim 1, characterized in that: The second layer includes: a piezoelectric layer, the piezoelectric layer includes a plurality of crystals, and the half-peak width of a rocking curve of a crystal composed of the plurality of crystals is less than 2.5 degrees.

24. The BAW resonator device according to claim 1, characterized in that: A second portion of the second electrode layer that overlaps with the first electrode layer is located above the first cavity, and a projection of the second portion perpendicular to the first layer is located within the first cavity.

25. The BAW resonator device according to claim 1, characterized in that: The material of the first electrode layer includes at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum; the material of the second electrode layer includes at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, and aluminum.

26. The BAW resonator device according to claim 1, characterized in that: The first electrode layer includes a first polarity, and the second electrode layer includes a second polarity.

27. The BAW resonator device according to claim 1, characterized in that: The first electrode layer includes a first polarity and a second polarity, and the second electrode layer includes the first polarity and the second polarity.

28. The BAW resonator device according to claim 1, characterized in that: Also includes: The second substrate is located on a second side of the first layer, and the second side is opposite to the first side.

29. The BAW resonator device according to claim 28, characterized in that: The material of the second substrate includes at least one of the following: silicon, silicon carbide, and glass.

30. The BAW resonator device according to claim 28, characterized in that: Also included is a film located between the first layer and the second substrate.

31. The BAW resonator device according to claim 30, characterized in that: The thin film includes: a polycrystalline thin film.

32. The BAW resonator device according to claim 31, characterized in that: The material of the polycrystalline thin film includes at least one of the following: polycrystalline silicon, polycrystalline silicon nitride, and polycrystalline silicon carbide.

33. A bulk acoustic wave filter device, characterized in that: include: At least one BAW resonator device as claimed in any one of claims 1 to 32.

Images