Resonator and its preparation method

Abstract

The present invention provides a resonator structure, which includes a substrate, a bottom electrode formed on the substrate, a piezoelectric layer formed on the bottom electrode, and a top electrode formed on the piezoelectric layer. The overlapping region of the top electrode, the piezoelectric layer and the bottom electrode is the resonant region. The resonator further includes a space formed in the resonant region. The surface of the bottom electrode away from the substrate is the first surface, and the surface of the top electrode facing the piezoelectric layer is the second surface. The space extends from the first surface in a direction away from the piezoelectric layer and / or from the second surface in a direction away from the piezoelectric layer; alternatively, the piezoelectric layer includes a bottom surface facing the bottom electrode and a top surface disposed opposite to the bottom surface and facing the top electrode, and the space extends from the bottom surface towards the top surface or from the top surface towards the bottom surface; the present invention also provides a method for manufacturing the resonator. Compared with the related art, the resonator structure of the present invention can reduce the energy loss of the device, improve the Q value and reduce the insertion loss.

Description

Technical Field

[0001] The present invention relates to the technical field of resonators, and in particular, to a resonator structure and a preparation method thereof.

Background Art

[0002] With the increasing number of intelligent devices and the continuous popularization of the Internet of Things and 5G technologies, the demand for high-performance filters and multiplexers is growing. As an important part of filters and multiplexers, acoustic resonators have been the focus of research in recent years. Currently, the mainstream acoustic resonance technologies include surface acoustic wave technology SAW (Surface Acoustic Wave) and bulk acoustic wave technology BAW (Bulk Acoustic Wave). Resonators using SAW technology occupy the mainstream market in the mid- and low-frequency ranges (below 2 GHz) due to their simple manufacturing process and low cost. The disadvantages of SAW resonators are low quality factor values, poor temperature drift of materials, and poor compatibility with semiconductor processes. Filters composed of such resonators have a poor rectangularity coefficient, high insertion loss, and large temperature drift of the center frequency. More critically, as the frequency increases, the spacing between the interdigital electrodes of SAW resonators decreases, which not only poses higher requirements for the process but also deteriorates the reliability of the device. These disadvantages are hindering the application of SAW resonators in higher frequency bands. The emergence of BAW resonators has improved many of the disadvantages of SAW resonators, and the mature semiconductor process has good compatibility with its manufacturing. However, due to the complex process and high manufacturing difficulty of BAW resonators themselves, the cost remains high, making it difficult to completely replace SAW resonators in the mid- and high-frequency bands and even having no competitiveness in the low-frequency band. In addition to its development in the communication field, due to its excellent performance, BAW resonators are also widely used in piezoelectric microphones, pressure sensors, or other sensor fields.

[0003] The BAW resonator is different from the SAW resonator. It utilizes longitudinal waves to generate resonance in the piezoelectric thin film, and the propagation direction of the longitudinal wave is the thickness direction of the piezoelectric material. By adjusting the thickness of the piezoelectric material and the electrode material, the resonance frequency of the resonator can be conveniently adjusted. To generate resonance, in addition to the piezoelectric material and the electrode layers oppositely arranged above and below it to generate electrical excitation, there is usually an acoustic mirror that reflects the wave energy at the interface. Air or a Bragg reflector is the most commonly used reflector structure. The Bragg reflector uses a laminated structure of multiple groups of low acoustic impedance materials and high acoustic impedance materials alternating to achieve wave reflection. Although this reflector has a high reflectivity, it still cannot avoid energy leakage along the reflector. Compared with the Bragg reflector, air has a better reflection effect on waves and blocks the path of energy leakage, so resonators with higher quality factors can often be manufactured. To introduce air as a reflector into the resonance structure, the related technology is to create a cavity structure in the substrate or on the substrate before depositing the electrode layer and the piezoelectric layer. Taking the formation of a cavity in the substrate as an example, a sacrificial material is filled in the cavity to make the surface flat, and then the electrode layer and the piezoelectric layer are deposited above the cavity and the substrate. Finally, an etching solution or atmosphere that can corrode the sacrificial material contacts the sacrificial material through a pre-reserved release channel to release the cavity and form an air mirror structure.

[0004] When the BAW resonator works, high-frequency voltages are applied to the top electrode and the bottom electrode respectively. Under the action of the alternating electric field, the piezoelectric material deforms, and the suspended film layer above the cavity or the acoustic mirror oscillates, generating longitudinal waves parallel to the thickness direction and clutter waves propagating perpendicular to the thickness direction (transversely). At a specific frequency alternating voltage, the suspended thin film will resonate to achieve special electrical characteristics. In the prior art, although the main mode during resonance is the longitudinal wave mode, however, there will still be some parasitic modes formed along with the excitation of the longitudinal wave. These parasitic modes can either be standing waves, forming clutter peaks on the electrical characteristic curve of the device, increasing the in-band ripple and insertion loss of the filter; or be clutter waves propagating transversely, causing energy leakage, increasing the insertion loss of the filter, and reducing the quality factor (Q value) of the device.

[0005] Therefore, it is necessary to provide a new resonator to solve the above technical problems.

Summary of the Invention

[0006] The purpose of the present invention is to provide a resonator structure that reduces energy loss, improves the Q value of the device, and reduces the insertion loss.

[0007] To achieve the above purpose, the present invention provides a resonator,

[0008] including:

[0009] a substrate;

[0010] A bottom electrode is formed on the substrate, and the surface of the bottom electrode away from the substrate is the first surface;

[0011] A piezoelectric layer is formed on the bottom electrode;

[0012] A top electrode is formed on the piezoelectric layer, and the surface of the top electrode facing the piezoelectric layer is the second surface; the overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is the resonant region;

[0013] A space is formed in the resonant region;

[0014] The space extends away from the piezoelectric layer from the first surface and / or extends away from the piezoelectric layer from the second surface.

[0015] Preferably, a cavity is provided on the substrate, and the cavity is located between the substrate and the bottom electrode or is provided in the substrate.

[0016] Preferably, an acoustic mirror is provided between the substrate and the bottom electrode. The acoustic mirror includes at least one layer of a first acoustic impedance material layer and at least one layer of a second acoustic impedance material layer. At least one layer of the first acoustic impedance material layer and at least one layer of the second acoustic impedance material layer are alternately stacked on the substrate, and the number of layers of the first acoustic impedance material layer is equal to the number of layers of the second acoustic impedance material layer.

[0017] Preferably, the acoustic impedance value of the first acoustic impedance material layer is greater than the acoustic impedance value of the second acoustic impedance material layer.

[0018] Preferably, the bottom electrode includes a third surface opposite to the first surface, and the space is spaced from the third surface.

[0019] Preferably, the top electrode includes a fourth surface opposite to the second surface, and the space is spaced from the fourth surface.

[0020] Preferably, the top electrode includes a side surface connecting the second surface and the fourth surface, and the space extends to the side surface.

[0021] Preferably, the space is filled with one or more materials such as air, silicon dioxide, silicon, silicon nitride.

[0022] Preferably, the bottom electrode and the top electrode can be made of one or more materials such as molybdenum, tungsten, platinum, aluminum, and the piezoelectric layer can be made of one or more piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, PZT.

[0023] The present invention also provides a method for manufacturing the resonator as described above, and the method includes the following steps:

[0024] Provide a substrate;

[0025] Deposit and form a bottom electrode on the substrate;

[0026] Deposit and form a piezoelectric layer on a side of the bottom electrode away from the substrate;

[0027] Deposit a sacrificial material on a side of the piezoelectric layer away from the bottom electrode and then pattern it to form a first sacrificial layer;

[0028] Deposit and form a top electrode on the first sacrificial layer and the side of the piezoelectric layer away from the bottom electrode;

[0029] Release the first sacrificial layer to form a space, thereby obtaining the resonator.

[0030] The present invention also provides another preparation method of the resonator as described above. The method includes the following steps:

[0031] Provide a substrate;

[0032] Etch the substrate to form a cavity, fill the cavity with a first sacrificial layer, and etch the first sacrificial layer to form a depression;

[0033] Deposit and form a bottom electrode on the substrate and the first sacrificial layer;

[0034] An area of the bottom electrode formed within the depression encloses a space, and a sacrificial material is filled in the space to form a second sacrificial layer;

[0035] Deposit and form a piezoelectric layer on the second sacrificial layer and the side of the bottom electrode away from the substrate;

[0036] Deposit and form a top electrode on a side of the piezoelectric layer away from the bottom electrode;

[0037] Release the first sacrificial layer and the second sacrificial layer, thereby obtaining the resonator.

[0038] The present invention also provides a resonator, including:

[0039] A substrate;

[0040] A bottom electrode formed on the substrate; a piezoelectric layer formed on the bottom electrode;

[0041] A top electrode formed on the piezoelectric layer; an overlapping area of the top electrode, the piezoelectric layer and the bottom electrode is a resonance area;

[0042] A space formed in the resonance area;

[0043] The piezoelectric layer includes a bottom surface facing the bottom electrode and a top surface disposed opposite to the bottom surface and facing the top electrode, and the space extends from the bottom surface toward the top surface or from the top surface toward the bottom surface.

[0044] Preferably, a cavity is provided on the substrate, and the cavity is located between the substrate and the bottom electrode or within the substrate.

[0045] Preferably, an acoustic mirror is provided between the substrate and the bottom electrode, and the acoustic mirror includes at least one layer of a first acoustic impedance material layer and at least one layer of a second acoustic impedance material layer. At least one layer of the first acoustic impedance material layer and at least one layer of the second acoustic impedance material layer are alternately stacked on the substrate, and the number of layers of the first acoustic impedance material layer is equal to the number of layers of the second acoustic impedance material layer.

[0046] Preferably, the acoustic impedance value of the first acoustic impedance material is greater than that of the second acoustic impedance material.

[0047] Preferably, the space extends from the bottom surface to the top surface of the piezoelectric layer.

[0048] Preferably, the space is filled with one or more materials such as air, silicon dioxide, silicon, silicon nitride, etc.

[0049] Preferably, the bottom electrode and the top electrode can be made of one or more materials such as molybdenum, tungsten, platinum, aluminum, etc., and the piezoelectric layer can be made of one or more piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, PZT, etc.

[0050] The present invention also provides a method for manufacturing a resonator as described above, and the method includes the following steps:

[0051] Provide a substrate;

[0052] Deposit and form a bottom electrode on the substrate;

[0053] Deposit and form a piezoelectric layer on a side of the bottom electrode away from the substrate, etch the piezoelectric layer to form a space on a side of the piezoelectric layer away from the bottom electrode, and fill the space with a sacrificial material to form a first sacrificial layer;

[0054] Deposit and form a top electrode on a side of the first sacrificial layer and the piezoelectric layer away from the bottom electrode;

[0055] Release the first sacrificial layer to obtain the resonator.

[0056] The present invention also provides another method for manufacturing a resonator as described above, and the method includes the following steps:

[0057] Provide a substrate;

[0058] Deposit and form a bottom electrode on the substrate;

[0059] Deposit a sacrificial material on the side of the bottom electrode away from the substrate and then pattern it to form a first sacrificial layer;

[0060] Deposit and form a piezoelectric layer on the side of the first sacrificial layer and the bottom electrode away from the substrate;

[0061] Deposit and form a top electrode on the side of the piezoelectric layer away from the bottom electrode;

[0062] Release the first sacrificial layer to form a space, thereby obtaining the resonator.

[0063] Compared with the related art, in the resonator of the present invention, the overlapping region of the top electrode, the piezoelectric layer and the bottom electrode is the resonance region. The resonator further includes a space formed in the resonance region. The bottom electrode includes a first surface close to the piezoelectric layer, and the top electrode includes a second surface facing the piezoelectric layer. The space extends from the first surface away from the piezoelectric layer and / or from the second surface away from the piezoelectric layer; or the piezoelectric layer includes a bottom surface facing the bottom electrode and a top surface opposite to the bottom surface and facing the top electrode. The space extends from the bottom surface towards the top surface or from the top surface towards the bottom surface; that is, through the above structural settings, a space is introduced into the resonance region, and most of the laterally propagating clutter will be reflected back into the resonance region, reducing the clutter propagating outside the resonance region, so that most of the energy is restricted within the resonance region, reducing energy loss, increasing the Q value of the resonator, and reducing the insertion loss. At the same time, after applying a high-frequency voltage, a main mode and a parasitic mode will be formed in both of the two resonance regions separated by the space. And in the space region, since the air gap separates the piezoelectric layer and the top electrode, no wave excitation will occur in this region; therefore, the parasitic modes propagating in opposite directions in the two resonance regions separated by the space cancel each other out, reducing the propagation of lateral clutter and the formation of lateral standing waves in the entire resonance region; by adjusting the sizes of the two resonance regions and the space region, specific frequency spurious peaks can be selectively eliminated or reduced, achieving the purpose of reducing the ripple in the passband, reducing the insertion loss, and improving the device performance.

Description of the Drawings

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings, where:

[0065] Figure 1 Schematic diagram of the structure of the resonator according to the first embodiment of the present invention;

[0066] Figure 2 is Figure 1 Cross-sectional view along A-A;

[0067] Figure 3 Cross-sectional view of the resonator with a sound reflector according to the first embodiment of the present invention;

[0068] Figure 4 Exploded view of the resonator according to the first embodiment of the present invention;

[0069] Figure 5 Another exploded view of the resonator according to the first embodiment of the present invention;

[0070] Figure 6 Cross-sectional view of the resonator according to the second embodiment of the present invention;

[0071] Figure 7 Cross-sectional view of the resonator according to the third embodiment of the present invention;

[0072] Figure 8 Cross-sectional view of the resonator according to the fourth embodiment of the present invention;

[0073] Figure 9 Cross-sectional view of the resonator according to the fifth embodiment of the present invention;

[0074] Figure 10 Preparation process of the resonator in the first embodiment of the present invention;

[0075] Figure 11 Schematic diagram of the structure in the preparation process of the resonator in the first embodiment of the present invention;

[0076] Figure 12 Preparation process of the resonator in the second embodiment of the present invention;

[0077] Figure 13 Schematic diagram of the structure in the preparation process of the resonator in the second embodiment of the present invention;

[0078] Figure 14 Preparation process of the resonator in the third embodiment of the present invention;

[0079] Figure 15 Schematic diagram of the structure in the preparation process of the resonator in the third embodiment of the present invention;

[0080] Figure 16 Preparation process of the resonator in the fourth embodiment of the present invention;

[0081] Figure 17 Schematic diagram of the structure in the preparation process of the resonator in the fourth embodiment of the present invention.

Detailed Description

[0082] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0083] Embodiment 1

[0084] Please refer to Figures 1-5 simultaneously. The present invention provides a resonator 100, which includes a substrate 1, a bottom electrode 2, a piezoelectric layer 3, and a top electrode 4 stacked in sequence from bottom to top.

[0085] Specifically, the bottom electrode 2 is formed on the substrate 1; the piezoelectric layer 3 is formed on the bottom electrode 2; the top electrode 4 is formed on the piezoelectric layer 3; the overlapping region of the top electrode 4, the piezoelectric layer 3, and the bottom electrode 2 is the resonance region 5; the resonator 100 further includes a space 10 formed in the resonance region 5.

[0086] The top electrode 4 includes a second surface 4a and a fourth surface 4b opposite to the second surface 4a. The second surface 4a is the surface of the top electrode 4 facing the piezoelectric layer 3; the space 10 extends from the second surface 4a in a direction away from the piezoelectric layer 3, and the space 10 is spaced from the fourth surface 4b, that is, in this embodiment, the space 10 does not penetrate the top electrode 4; as Figure 2 shown, a cavity 110 is provided on the substrate 1, and the cavity 110 is located between the substrate 1 and the bottom electrode 2 or is provided in the substrate 1. Of course, in other embodiments, the cavity 110 may not be provided, and it is specifically designed according to actual requirements.

[0087] As Figure 3As shown, an acoustic mirror 12 is provided between the substrate 1' and the bottom electrode 2'. The acoustic mirror 12 includes at least one first acoustic impedance material layer 12a and at least one second acoustic impedance material layer 12b. At least the one first acoustic impedance material layer 12a and at least one of the second acoustic impedance material layers 12b are alternately stacked on the substrate 1'. The number of layers of the first acoustic impedance material layer 12a is equal to that of the second acoustic impedance material layer 12b. Preferably, the acoustic impedance value of the first acoustic impedance material layer 12a is greater than that of the second acoustic impedance material layer 12b. The first acoustic impedance material layer 12a may be a high acoustic impedance material such as tungsten or molybdenum, while the second acoustic impedance material layer 12b may be a low acoustic impedance material such as silicon dioxide, silicon nitride, or aluminum nitride. The top electrode 4 includes a side surface 4c' connecting the second surface 4a' and the fourth surface 4b', and the space 10' can extend to the side surface 4c'. It should be noted that the substrate 1 of the present invention may or may not be provided with a cavity 110, or an acoustic mirror 12 may be provided between the substrate 1' and the bottom electrode 2'. The space 10 or 10' may or may not extend to the side surface of the top electrode 4, which can be selected according to the actual product design and will not be elaborated further below.

[0088] The orthographic projection of the top electrode 4 onto the substrate 1 after removing the part connected to the external circuit is a tapered hexagon. Of course, it can also be other shapes, such as a tapered pentagon or an ellipse. The tapered hexagon is not a regular hexagon, and similarly, the tapered pentagon is not a regular pentagon.

[0089] See Figure 2 As shown, the resonant region 5 includes a first resonant region 51 surrounded by the space 10, a second resonant region 52 corresponding to the space 10, and a third resonant region 53 outside the space 10.

[0090] After applying a high-frequency voltage, both the main mode and the parasitic mode will be formed in the first resonant region 51 and the third resonant region 53. However, in the second resonant region 52, since the sealed space 10 separates the piezoelectric layer 3 and the top electrode 4, no wave excitation will occur in the second resonant region 52. As Figure 2 shown by the upper arrow, the parasitic modes propagating in opposite directions in the first resonant region 51 and the third resonant region 53 cancel each other out, reducing the propagation of transverse clutter and the formation of transverse standing waves in the entire resonant region 5. By adjusting the sizes of the first resonant region 51, the second resonant region 52, and the third resonant region 53, specific frequency spurious peaks can be selectively eliminated or reduced, achieving the purpose of reducing the ripple in the passband, lowering the insertion loss, and improving the device performance.

[0091] In this embodiment, the space is filled with one or more materials such as air, silicon dioxide, silicon, silicon nitride, etc. The bottom electrode 2 and the top electrode 4 are both made of one or more materials such as molybdenum, tungsten, platinum, aluminum, etc. The piezoelectric layer 3 is made of one or more piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, PZT, etc. Of course, it can also be made of other materials.

[0092] This embodiment also provides a method for manufacturing a resonator 100. Refer Figure 10 and Figure 11 As shown, this method includes the following steps:

[0093] S1. Provide a substrate 1, as Figure 11 shown in a;

[0094] S2. Deposit and form a bottom electrode 2 on the substrate 1, as Figure 11 shown in b;

[0095] S3. Deposit and form a piezoelectric layer 3 on the side of the bottom electrode 2 away from the substrate 1, as Figure 11 shown in c;

[0096] S4. Deposit a sacrificial material a on the side of the piezoelectric layer 3 away from the bottom electrode 1 and then pattern it to form a first sacrificial layer 10a, as Figure 11 shown in d;

[0097] S5. Deposit and form a top electrode 4 on the side of the first sacrificial layer 10a and the piezoelectric layer 3 away from the bottom electrode 1, as Figure 11 shown in e;

[0098] S6. Release the first sacrificial layer 10a to form a space 10, thereby obtaining the resonator 100, as Figure 11 shown in f.

[0099] In the resonator 100 obtained according to the above steps, the space 10 extends from the second surface 4a in a direction away from the piezoelectric layer 3. The space 10 causes most of the laterally propagating clutter to be reflected back to the resonance region, reducing the clutter propagating outside the resonance region, so that most of the energy is confined within the resonance region, reducing energy loss, increasing the Q value of the resonator, and reducing the insertion loss.

[0100] Embodiment Two

[0101] Please refer to Figure 6, this embodiment provides a resonator 200, whose structure is substantially the same as that of the resonator 100 in Embodiment 1. The difference is that the bottom electrode 22 includes a first surface 22a and a third surface 22b opposite to the first surface 22a, and the first surface 22a is the surface of the bottom electrode 22 away from the substrate 12; the space 102 extends from the first surface 22a in a direction away from the piezoelectric layer 3, and the space 102 is spaced apart from the third surface 22b.

[0102] This embodiment also provides a method for manufacturing a resonator 200. Refer to Figure 12 and Figure 13 as shown, this method includes the following steps:

[0103] S11, provide a substrate 12, etch the substrate 12 to form a cavity 12c, fill a first sacrificial layer 12d in the cavity 12c, and etch the first sacrificial layer 12d to form a depression; as Figure 13 shown in a;

[0104] S21, deposit and form a bottom electrode 22 on the substrate 12 and the first sacrificial layer 12d, as Figure 13 shown in b;

[0105] S31, the area of the bottom electrode 22 formed within the depression encloses to form a space 102, fill a sacrificial material 2a in the space to form a second sacrificial layer 102a, as Figure 13 shown in c;

[0106] S41, deposit and form a piezoelectric layer 32 on the second sacrificial layer 102a and the side of the bottom electrode 22 away from the substrate 12, as Figure 13 shown in d;

[0107] S51, deposit and form a top electrode 42 on the side of the piezoelectric layer 32 away from the bottom electrode 22, as Figure 13 shown in e;

[0108] S61, release the first sacrificial layer 12d and the second sacrificial layer 102a, thereby obtaining the resonator 200, as Figure 13 shown in f.

[0109] Of course, Embodiment 1 and Embodiment 2 can also be combined, that is, there are two spaces 102. One of the spaces 102 extends from the first surface 22a in a direction away from the piezoelectric layer 32, and the other space 102 extends from the second surface 42a in a direction away from the piezoelectric layer 32. These can all be adjusted according to actual needs.

[0110] Embodiment 3

[0111] Please refer to Figure 7, this embodiment provides a resonator 300, whose structure is substantially the same as that of the resonator 100 in the first embodiment. The difference is that the piezoelectric layer 33 includes a bottom surface 332 facing the bottom electrode 23 and a top surface 331 opposite to the bottom surface 332 and facing the top electrode 43. The space 103 extends from the top surface 331 towards the bottom surface 332, and the space 103 does not penetrate through the piezoelectric layer 33.

[0112] This embodiment also provides a method for manufacturing a resonator 300. Refer to Figure 14 and Figure 15 as shown. This method includes the following steps:

[0113] S12, provide a substrate 13, as Figure 15 shown in a;

[0114] S22, deposit and form a bottom electrode 23 on the substrate 13, as Figure 15 shown in b;

[0115] S32, deposit and form a piezoelectric layer 33 on the side of the bottom electrode 23 away from the substrate 13, etch the piezoelectric layer 33 to form a space 103 on its side away from the bottom electrode 23, and fill the sacrifice material 3a in the space to form a first sacrifice layer 103a, as Figure 15 shown in c;

[0116] S42, deposit and form a top electrode 43 on the first sacrifice layer 103a and the side of the piezoelectric layer 33 away from the bottom electrode 23, as Figure 15 shown in d;

[0117] S52, release the first sacrifice layer 103a, thereby obtaining the resonator 300, as Figure 15 shown in e.

[0118] Embodiment Four

[0119] Please refer to Figure 8 , this embodiment provides a resonator 400, whose structure is substantially the same as that of the resonator 100 in the first embodiment. The difference is that the piezoelectric layer 34 includes a bottom surface 342 facing the bottom electrode 24 and a top surface 341 opposite to the bottom surface 342 and facing the top electrode 44. The space 104 extends from the bottom surface 342 towards the top surface 341, and the space 104 does not penetrate through the piezoelectric layer 34.

[0120] This embodiment also provides a method for manufacturing a resonator 400. Refer to Figure 16 and Figure 17 as shown. This method includes the following steps:

[0121] S13, Provide a substrate 14, as Figure 17 shown in a;

[0122] S23, Deposit and form a bottom electrode 24 on the substrate 14, as Figure 17 shown in b;

[0123] S33, Deposit a sacrificial material 4a on the side of the bottom electrode 24 away from the substrate 14 and then pattern it to form a first sacrificial layer 104a, as Figure 17 shown in c;

[0124] S43, Deposit and form a piezoelectric layer 34 on the side of the first sacrificial layer 104a and the bottom electrode 24 away from the substrate 14, as Figure 17 shown in d;

[0125] S53, Deposit and form a top electrode 44 on the side of the piezoelectric layer 34 away from the bottom electrode 24, as Figure 17 shown in e;

[0126] S63, Release the first sacrificial layer 104a to form a space 104, thereby obtaining the resonator 400, as Figure 17 shown in f.

[0127] Example Five

[0128] Please refer to Figure 9 , This example provides a resonator 500, whose structure is substantially the same as that of the resonator 300 in Example Three. The difference is that the space 105 extends from the top surface 351 to the bottom surface 352 of the piezoelectric layer, that is, the space 105 reaches the maximum, with less energy loss, improving the Q value of the resonator and reducing the insertion loss. The preparation method of the resonator 500 in this example is the same as that of the resonator 300 in Example Three, except that when etching the piezoelectric layer, the piezoelectric layer is etched through and filled to be flush with the height of the first sacrificial layer.

[0129] Compared with the related art, in the resonator of the present invention, the overlapping region of the top electrode, the piezoelectric layer and the bottom electrode is the resonance region. The resonator further includes a space formed in the resonance region. The bottom electrode includes a first surface facing the piezoelectric layer, and the top electrode includes a second surface facing the piezoelectric layer. The space extends from the first surface away from the piezoelectric layer and / or from the second surface away from the piezoelectric layer; or the piezoelectric layer includes a bottom surface facing the bottom electrode and a top surface opposite to the bottom surface and facing the top electrode. The space extends from the bottom surface towards the top surface or from the top surface towards the bottom surface; that is, through the above structural arrangement, a space is introduced into the resonance region, and most of the laterally propagating clutter will be reflected back into the resonance region, reducing the clutter propagating outside the resonance region, so that most of the energy is confined within the resonance region, reducing energy loss, increasing the Q value of the resonator, and reducing the insertion loss. At the same time, after applying a high-frequency voltage, the main mode and the parasitic mode will be formed in both of the two resonance regions separated by the space. Since the air gap separates the piezoelectric layer and the top electrode in the space region, no wave excitation will occur in this region; therefore, the parasitic modes propagating in opposite directions in the two resonance regions separated by the space cancel each other out, reducing the propagation of lateral clutter and the formation of lateral standing waves in the entire resonance region; by adjusting the sizes of the two resonance regions and the space region, specific frequency spurious peaks can be selectively eliminated or reduced, achieving the purpose of reducing the ripple in the passband, reducing the insertion loss, and improving the device performance.

[0130] The above are only the embodiments of the present invention. It should be noted here that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, improvements can still be made, but these all belong to the protection scope of the present invention.

Claims

1. A resonator, characterized in that, Comprising: A substrate; A bottom electrode formed on the substrate, and a first surface of the bottom electrode away from the substrate; A piezoelectric layer formed on the bottom electrode; A top electrode formed on the piezoelectric layer, and a second surface of the top electrode facing the piezoelectric layer; The overlapping region of the top electrode, the piezoelectric layer and the bottom electrode is a resonant region; A space formed in the resonant region; The space extends from the first surface in a direction away from the piezoelectric layer and / or from the second surface in a direction away from the piezoelectric layer; The resonant region includes a first resonant region surrounded by the space, a second resonant region corresponding to the space, and a third resonant region outside the space.

2. The resonator according to claim 1, wherein A cavity is provided on the substrate, and the cavity is located between the substrate and the bottom electrode or provided in the substrate.

3. The resonator according to claim 1, characterized in that, An acoustic mirror is provided between the substrate and the bottom electrode, and the acoustic mirror includes at least one first acoustic impedance material layer and at least one second acoustic impedance material layer. At least one of the first acoustic impedance material layers and at least one of the second acoustic impedance material layers are alternately stacked on the substrate, and the number of layers of the first acoustic impedance material layer is equal to the number of layers of the second acoustic impedance material layer.

4. The resonator according to claim 3, wherein The acoustic impedance value of the first acoustic impedance material layer is greater than the acoustic impedance value of the second acoustic impedance material layer.

5. The resonator according to claim 1, wherein The bottom electrode includes a third surface opposite to the first surface, and the space is spaced from the third surface.

6. The resonator according to claim 1, characterized in that, The top electrode includes a fourth surface opposite to the second surface, and the space is spaced from the fourth surface.

7. The resonator according to claim 6, wherein The top electrode includes a side surface connecting the second surface and the fourth surface, and the space extends to the side surface.

8. The resonator according to claim 1, characterized in that, The space is filled with one or more materials such as air, silicon dioxide, silicon, silicon nitride, etc.

9. The resonator according to claim 1, wherein The bottom electrode and the top electrode can be made of one or more materials such as molybdenum, tungsten, platinum, aluminum, etc., and the piezoelectric layer can be made of one or more piezoelectric materials such as aluminum nitride, scandium-doped aluminum nitride, zinc oxide, PZT, etc.

10. A method for preparing a resonator according to any one of claims 1-9, characterized in that, The method includes the following steps: Providing a substrate; Depositing and forming a bottom electrode on the substrate; Depositing and forming a piezoelectric layer on a side of the bottom electrode away from the substrate; Depositing a sacrificial material on a side of the piezoelectric layer away from the bottom electrode and patterning it to form a first sacrificial layer; Depositing and forming a top electrode on the first sacrificial layer and the side of the piezoelectric layer away from the bottom electrode; Releasing the first sacrificial layer to form a space, thereby obtaining the resonator.

11. A method for preparing a resonator according to any one of claims 1-9, characterized in that, The method includes the following steps: Providing a substrate; Etching the substrate to form a cavity, filling a first sacrificial layer in the cavity, and etching the first sacrificial layer to form a depression; Depositing and forming a bottom electrode on the substrate and the first sacrificial layer; The region of the bottom electrode formed in the depression encloses a space, and a sacrificial material is filled in the space to form a second sacrificial layer; Depositing and forming a piezoelectric layer on the second sacrificial layer and the side of the bottom electrode away from the substrate; Depositing and forming a top electrode on the side of the piezoelectric layer away from the bottom electrode; Releasing the first sacrificial layer and the second sacrificial layer, thereby obtaining the resonator.

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