Lamb wave resonator and method for manufacturing lamb wave resonator

Abstract

The invention discloses a Lamb wave resonator and a manufacturing method of the Lamb wave resonator, and the Lamb wave resonator comprises a substrate which is provided with a cavity; the piezoelectric layer is arranged on the upper surface of the substrate; the plurality of top electrodes are arranged on the upper surface of the piezoelectric layer; the bottom electrodes are arranged on the lower surface of the piezoelectric layer, the bottom electrodes are exposed out of the lower surface of the substrate through the cavity, and the top electrodes and the bottom electrodes are alternately arranged in the first horizontal direction at intervals. The Lamb wave resonator has the advantages of being good in clutter suppression effect, high in quality factor and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency filter device manufacturing, and in particular to a Lamb wave resonator and a method for manufacturing the Lamb wave resonator. Background Art

[0002] Ideally, a Lamb wave resonator would have only one resonant mode within the operating frequency band, namely the first-order antisymmetric mode (A1 mode), and its impedance curve would be a pure curve without burrs.

[0003] In the related technology, the Lamb wave resonator faces the problem of complex spurious modes, which is manifested in many burrs on the impedance curve. Each burr means a noise. The existence of noise will affect the Q value (quality factor) and electromechanical coupling coefficient of the resonator, reduce the figure of merit (FOM) of the resonator, and have a negative impact on the design of the filter, such as causing in-band depressions and affecting the steep drop of the transition band. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a Lamb wave resonator, which has the advantages of good clutter suppression effect and high quality factor.

[0005] The invention also provides a method for manufacturing the Lamb wave resonator.

[0006] To achieve the above-mentioned purpose, according to an embodiment of the first aspect of the present invention, a Lamb wave resonator is provided, the Lamb wave resonator comprising: a substrate having a cavity thereon; a piezoelectric layer, the piezoelectric layer being arranged on the upper surface of the substrate; a plurality of top electrodes, the plurality of top electrodes being arranged on the upper surface of the piezoelectric layer; a plurality of bottom electrodes, the plurality of bottom electrodes being arranged on the lower surface of the piezoelectric layer, the plurality of bottom electrodes being exposed from the lower surface of the substrate through the cavity, and the plurality of top electrodes and the plurality of bottom electrodes being alternately arranged in a first horizontal direction.

[0007] The Lamb wave resonator according to the embodiment of the present invention has the advantages of good clutter suppression effect and high quality factor.

[0008] In addition, the Lamb wave resonator according to the above embodiment of the present invention may also have the following additional technical features:

[0009] According to an embodiment of the present invention, each of the plurality of top electrodes and the plurality of bottom electrodes is oriented along a second horizontal direction, and the first horizontal direction is perpendicular to the second horizontal direction.

[0010] According to an embodiment of the present invention, intervals between adjacent top electrodes and adjacent bottom electrodes are equal.

[0011] According to an embodiment of the present invention, each of the top electrodes and the bottom electrodes has the same width in the first horizontal direction, and the width of each of the top electrodes and the bottom electrodes is 10%-50% of the interval between adjacent top electrodes and the bottom electrodes.

[0012] According to one embodiment of the present invention, the Lamb wave resonator also includes a first busbar and a second busbar, the first busbar is respectively connected to the plurality of top electrodes, the first busbar is arranged on the upper surface of the piezoelectric layer, the piezoelectric layer is provided with a through hole, the second busbar is respectively connected to the plurality of bottom electrodes and extends from the lower surface of the piezoelectric layer through the through hole to the upper surface of the piezoelectric layer.

[0013] According to one embodiment of the present invention, the thickness of the piezoelectric layer is less than 0.5 times the wavelength of the first-order antisymmetric Lamb wave.

[0014] According to one embodiment of the present invention, the piezoelectric layer is a Z-cut or 128Y-cut single crystal lithium niobate piezoelectric film, and the top electrode and the bottom electrode are aluminum, platinum, chromium, titanium or copper.

[0015] According to an embodiment of the present invention, the shape of the cross section of the cavity parallel to the vertical direction and the first horizontal direction is a rectangle, a trapezoid or a parallelogram.

[0016] According to an embodiment of the second aspect of the present invention, a method for manufacturing a Lamb wave resonator is provided. The method for manufacturing a Lamb wave resonator according to an embodiment of the present invention comprises the following steps:

[0017] providing a substrate;

[0018] Processing a plurality of bottom electrode grooves on the upper surface of the substrate;

[0019] preparing a plurality of bottom electrodes in a plurality of the bottom electrode grooves;

[0020] Preparing a piezoelectric layer on the upper surface of the substrate;

[0021] A plurality of top electrodes are prepared on the upper surface of the piezoelectric layer, wherein the plurality of top electrodes and the plurality of bottom electrodes are alternately arranged in a first horizontal direction;

[0022] A cavity is processed on the lower surface of the substrate so that the bottom electrode is exposed from the lower surface of the substrate through the cavity.

[0023] The method for manufacturing a Lamb wave resonator according to an embodiment of the present invention has the advantages of good clutter suppression effect and high quality factor.

[0024] According to one embodiment of the present invention, the method for manufacturing the Lamb wave resonator comprises the following steps:

[0025] Providing a substrate, the substrate comprising a substrate body and an oxide layer located on an upper surface of the substrate body;

[0026] etching a plurality of bottom electrode grooves on the oxide layer;

[0027] Depositing a plurality of bottom electrodes in a plurality of the bottom electrode grooves;

[0028] Preparing a piezoelectric material layer on the upper surface of the substrate, the piezoelectric material layer comprising an ion implantation layer below and a non-ion implantation layer above, and removing the non-ion implantation layer to form a piezoelectric layer;

[0029] Depositing a plurality of top electrodes on the upper surface of the piezoelectric layer, wherein the plurality of top electrodes and the plurality of bottom electrodes are alternately arranged in a first horizontal direction;

[0030] Etching a cavity on the lower surface of the substrate body by deep reactive ion etching until the oxide layer is exposed;

[0031] The oxide layer is etched by using a buffered oxide etching solution to eliminate the oxide layer between the cavity and the piezoelectric layer so that the bottom electrode is exposed from the lower surface of the substrate through the cavity.

[0032] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0034] Figure 1 is a cross-sectional view of a Lamb wave resonator according to an embodiment of the present invention.

[0035] Figure 2 is a schematic structural diagram of a Lamb wave resonator according to an embodiment of the present invention.

[0036] Figure 3 is a partial cross-sectional view of a Lamb wave resonator according to an embodiment of the present invention.

[0037] Figure 4 Schematic diagram of a local acoustic vibration model of a Lamb wave resonator according to an embodiment of the present invention.

[0038] Figure 5 It is a schematic diagram of an impedance curve of a Lamb wave resonator in the related art.

[0039] Figure 6 Schematic diagram of an impedance curve of a Lamb wave resonator according to an embodiment of the present invention.

[0040] Figure 7 It is a schematic diagram of the vibration shape of the spurious mode of the Lamb wave resonator in the related art.

[0041] Figure 8 Schematic diagram of the vibration shape of the spurious mode of the Lamb wave resonator according to an embodiment of the present invention.

[0042] Fig. 9 Schematic diagram of the manufacturing process of a Lamb wave resonator according to an embodiment of the present invention.

[0043] Fig.10 is a flow chart of a method for manufacturing a Lamb wave resonator according to an embodiment of the present invention.

[0044] Figure numerals: Lamb wave resonator 1, substrate 10, cavity 11, substrate body 12, oxide layer 13, piezoelectric layer 20, top electrode 30, first busbar 31, bottom electrode 40, second busbar 41, mask layer 2, bottom electrode groove 3, ion implantation layer 4, non-ion implantation layer 5, through hole 6. DETAILED DESCRIPTION

[0045] This application is based on the inventor's discovery and understanding of the following facts and problems:

[0046] The Lamb wave resonator in the related technology faces the problem of complex spurious modes, which is manifested in many burrs on the impedance curve. Each burr means a noise. The existence of noise will affect the Q value and electromechanical coupling coefficient of the resonator, reduce the figure of merit of the resonator, and have a negative impact on the design of the filter, such as causing in-band depressions and affecting the steep drop of the transition band.

[0047] Specifically, in the Lamb wave resonator in the related art, the interdigitated electrodes are all located on the same horizontal plane, for example, all located on the upper surface of the substrate. Because each electrode of the interdigitated electrodes is periodically distributed horizontally on the surface of the substrate, the stray mode is more easily enhanced due to the horizontal periodic resonance of the electric field, resulting in more noise, affecting the Q value and electromechanical coupling coefficient of the resonator, and reducing the figure of merit of the resonator.

[0048] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0049] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] The Lamb wave resonator 1 according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0052] like Figure 1-Figure 10 As shown, the Lamb wave resonator 1 according to the embodiment of the present invention includes a substrate 10 , a piezoelectric layer 20 , a plurality of top electrodes 30 and a plurality of bottom electrodes 40 .

[0053] The substrate 10 has a cavity 11. The piezoelectric layer 20 is disposed on the upper surface of the substrate 10 (the up-down, left-right, and front-back directions are indicated by arrows in the figure and are only for ease of description, not for limiting the actual setting direction). A plurality of top electrodes 30 are disposed on the upper surface of the piezoelectric layer 20. A plurality of bottom electrodes 40 are disposed on the lower surface of the piezoelectric layer 20, and the plurality of bottom electrodes 40 are exposed from the lower surface of the substrate 10 through the cavity 11. The plurality of top electrodes 30 and the plurality of bottom electrodes 40 are alternately arranged in a first horizontal direction (the horizontal direction is perpendicular to the up-down direction, Figure 1-Figure 4 In the illustrated embodiment, the first horizontal direction is the left-right direction).

[0054] Specifically, the substrate 10 may include a substrate body 12 and an oxide layer 13. During manufacturing, the oxide layer 13 may be processed separately to facilitate the preparation of the bottom electrode 40. The piezoelectric layer 20 may be a thin film layer. The plurality of top electrodes 30 and the plurality of bottom electrodes 40 form an interdigitated electrode structure.

[0055] The top electrode 30 and the bottom electrode 40 are suitable for forming a non-completely horizontal electric field under the excitation of an AC power source, and are distributed in the piezoelectric layer 20 in a corrugated shape.

[0056] like Figure 4 As shown, an adjacent top electrode 30 and a bottom electrode 40 together constitute a minimum period of the interdigital electrodes. An RF voltage is applied to the interdigital electrodes, and this voltage generates a time-varying oblique electric field B between the interdigital fingers. Since the annular Lamb wave resonator for suppressing noise adopts a relatively low metallization rate and the piezoelectric layer 20 has a higher dielectric constant relative to air, as well as the positional relationship between the top electrode 30 and the bottom electrode 40, the electric field is mainly distributed in the piezoelectric layer 20 along the dotted line direction, and a small part is oblique, parallel or perpendicular to the surface of the piezoelectric layer 20. The oblique electric field B excites shear deformation, thereby strongly exciting an acoustic vibration mode of a primary shear body wave in the piezoelectric layer 20. The shear deformation is shown in FIG. Figure 4 As shown in A, Figure 4 The small arrow at A in the figure shows the direction and size of atomic movement (for the sake of convenience, the degree of atomic movement in the figure and the thickness of the piezoelectric film are significantly exaggerated compared to the actual situation.) This excited shear mode is the working mode of the Lamb wave resonator, called the antisymmetric Lamb wave mode or A1 mode.

[0057] Figure 5 and Figure 6 The impedance curves of the Lamb wave resonator 1 in which the top electrode 30 and the bottom electrode 40 are staggered on the top and bottom surfaces of the piezoelectric layer 20 in the embodiment of the present invention are compared. Figure 5 is the impedance curve of the Lamb wave resonator (128YX cut) in the related art, Figure 6 The impedance curve of Lamb wave resonator 1 (128YX cut). Take the Lamb wave resonator with 20% metallization rate with electrode thickness of 420nm and piezoelectric layer thickness of 400nm as an example. The A1 mode corresponds to Figure 5 The maximum resonance peak in ①(or Figure 6 ⑤) in Figure 5 and Figure 6 The absolute bandwidth is about 1100MHz. The Lamb wave resonator in the related art has many clutters near the A1 mode, such as Figure 5 From ②, ③ and ④, we can see Figure 5 ② and ④ in correspond to Figure 6 ⑥ and ⑦ in Figure 6 The clutter in is obviously suppressed, and clutter ③ disappears completely.

[0058] Figure 7 and Figure 8Schematic diagrams of several specific noise mode vibration shapes of the Lamb wave resonator in the related art and the Lamb wave resonator 1 of the embodiment of the present invention are shown. The color represents the displacement of the particle in the horizontal direction, red to the left and blue to the right, and the depth of the color represents the displacement amplitude. ①(⑤) represents the standard A1 mode, which is also the main working mode of the resonator. The noise ② is suppressed, and corresponding to ⑥, the vibration amplitude in the piezoelectric layer 20 is significantly reduced. The reason is that compared with the horizontal electric field in the Lamb wave resonator in the related art, the electric field of the Lamb wave resonator 1 in which the top electrode 30 and the bottom electrode 40 are staggered on the top and bottom surfaces of the piezoelectric layer 20 is arranged in a wavy manner, slightly inclined to the horizontal plane, and the noise resonance in the piezoelectric layer 20 is destroyed. The noise ③ is the vibration that mainly exists inside the electrode. It completely disappears in the Lamb wave resonator 1 of the embodiment of the present invention because the arrangement of the top electrode 30 and the bottom electrode 40 up and down destroys the resonance of each electrode of different polarity on the same horizontal plane. The noise ④ and ⑦ are a mode of the A1 mode coupled with the transverse harmonic. The vibration mode is similar to the A1 mode, but the vibration direction is opposite to it, and the vibration has a vertical component, which is reflected in the wave interface in the vibration mode diagram. There are local changes in the three-time particle motion in the noise ④ and ⑦ (the trough of the wave interface), and the change in ⑦ is weaker than that in ④, which shows that the Lamb wave resonator 1 of the embodiment of the present invention suppresses this noise.

[0059] According to the Lamb wave resonator 1 of the embodiment of the present invention, by arranging the top electrode 30 and the bottom electrode 40, the top electrode 30 and the bottom electrode 40 are respectively located on the upper surface and the lower surface of the piezoelectric layer 20, and a plurality of top electrodes 30 and a plurality of bottom electrodes 40 are alternately arranged in the first horizontal direction, so that the top electrode 30 and the bottom electrode 40 are suitable for forming an electric field that is not completely horizontal but slightly inclined to the horizontal plane under the excitation of an AC power supply, and are distributed in a corrugated shape inside the piezoelectric layer 20, so that some stray modes cannot be strengthened by the periodic resonance of the horizontal transverse electric field, so that the clutter can be suppressed, which is beneficial to improving the Q value of the Lamb wave resonator 1.

[0060] Therefore, the Lamb wave resonator 1 according to the embodiment of the present invention has the advantages of good clutter suppression effect and high quality factor.

[0061] The Lamb wave resonator 1 according to a specific embodiment of the present invention will be described below with reference to the accompanying drawings.

[0062] In some specific embodiments of the present invention, Figure 1-Figure 10 As shown, the Lamb wave resonator 1 according to the embodiment of the present invention includes a substrate 10 , a piezoelectric layer 20 , a plurality of top electrodes 30 and a plurality of bottom electrodes 40 .

[0063] Specifically, Figure 1-Figure 4 As shown, each of the plurality of top electrodes and the plurality of bottom electrodes is oriented along a second horizontal direction ( Figure 1The second horizontal direction is the front-to-back direction), and the first horizontal direction is perpendicular to the second horizontal direction. This can facilitate the parallel and spaced arrangement of the top electrode 30 and the bottom electrode 40, thereby improving the effect of suppressing clutter.

[0064] More specifically, Figure 1-Figure 4 As shown, the intervals between adjacent top electrodes 30 and bottom electrodes 40 are equal. In this way, the distances between adjacent electrodes are equal, and multiple electrodes are arranged at equal intervals, which is convenient for improving the suppression effect of clutter.

[0065] Alternatively, if Figure 1-Figure 4 As shown, each top electrode 30 and bottom electrode 40 have the same width in the first horizontal direction, and the width of each top electrode 30 and bottom electrode 40 is 10%-50% of the spacing between adjacent top electrodes 30 and bottom electrodes 40. In this way, the electrodes can have a reasonable size and spacing, which is convenient for forming an electric field slightly inclined to the horizontal plane, and is convenient for improving the suppression effect of clutter.

[0066] Figure 1 and Figure 2 1 shows a Lamb wave resonator 1 according to some examples of the present invention. Figure 1 and Figure 2 As shown, the Lamb wave resonator 1 further includes a first busbar 31 and a second busbar 41, the first busbar 31 is respectively connected to a plurality of top electrodes 30, the first busbar 31 is arranged on the upper surface of the piezoelectric layer 20, a through hole 6 is arranged on the piezoelectric layer 20, and the second busbar 41 is respectively connected to a plurality of bottom electrodes 40 and extends from the lower surface of the piezoelectric layer 20 through the through hole 6 to the upper surface of the piezoelectric layer 20. In this way, the electrical connection between the plurality of top electrodes 30 and the plurality of bottom electrodes 40 can be facilitated, and by extending the second busbar 41 to the upper surface of the piezoelectric layer 20, the wiring of the first busbar 31 and the second busbar 41 can be facilitated.

[0067] Specifically, the thickness of the piezoelectric layer 20 is less than 0.5 times the wavelength of the first-order antisymmetric Lamb wave. This can further facilitate the formation of an electric field slightly inclined to the horizontal plane, thereby improving the effect of suppressing clutter.

[0068] Optionally, the piezoelectric layer 20 is a Z-cut or 128Y-cut single crystal lithium niobate piezoelectric film, and the top electrode 30 and the bottom electrode 40 are aluminum, platinum, chromium, titanium or copper. This can improve the electromechanical coupling coefficient of the Lamb wave resonator 1 and increase the bandwidth and frequency of the Lamb wave resonator 1.

[0069] Further, the shape of the cross section of the cavity 11 parallel to the vertical direction and the first horizontal direction is a rectangle, a trapezoid or a parallelogram. In other words, the shape of the cross section of the cavity 11 perpendicular to the second horizontal direction is a rectangle, a trapezoid or a parallelogram. This can facilitate the processing of the cavity 11.

[0070] Reference below Fig. 9 and Fig.10 The method for manufacturing a Lamb wave resonator according to an embodiment of the present invention is described. The method for manufacturing a Lamb wave resonator according to an embodiment of the present invention comprises the following steps:

[0071] Providing a substrate 10;

[0072] A plurality of bottom electrode grooves 3 are processed on the upper surface of the substrate 10;

[0073] Preparing a plurality of bottom electrodes 40 in the plurality of bottom electrode grooves 3;

[0074] A piezoelectric layer 20 is formed on the upper surface of the substrate 10;

[0075] A plurality of top electrodes 30 are prepared on the upper surface of the piezoelectric layer 20, and the plurality of top electrodes 30 and the plurality of bottom electrodes 40 are alternately arranged in a first horizontal direction;

[0076] A cavity 11 is processed on the lower surface of the substrate 10 so that the bottom electrode 40 is exposed from the lower surface of the substrate 10 through the cavity 11 .

[0077] According to the method for manufacturing a Lamb wave resonator of an embodiment of the present invention, by preparing a top electrode 30 and a bottom electrode 40, the top electrode 30 and the bottom electrode 40 are respectively located on the upper surface and the lower surface of the piezoelectric layer 20, and a plurality of top electrodes 30 and a plurality of bottom electrodes 40 are alternately arranged in a first horizontal direction, so that the top electrode 30 and the bottom electrode 40 are suitable for forming an electric field that is not completely horizontal but slightly inclined to the horizontal plane under the excitation of an AC power supply, and are distributed in a corrugated shape inside the piezoelectric layer 20, so that some stray modes cannot be strengthened by the periodic resonance of the horizontal transverse electric field, so that the clutter can be suppressed, which is beneficial to improving the Q value of the Lamb wave resonator.

[0078] Therefore, the method for manufacturing a Lamb wave resonator according to an embodiment of the present invention has the advantages of good clutter suppression effect and high quality factor.

[0079] Specifically, the method for manufacturing a Lamb wave resonator according to an embodiment of the present invention comprises the following steps:

[0080] S1, providing a substrate 10, wherein the substrate 10 includes a substrate body 12 and an oxide layer 13 located on an upper surface of the substrate body 12;

[0081] S2, etching a plurality of bottom electrode grooves 3 on the oxide layer 13;

[0082] S3, depositing a plurality of bottom electrodes 40 in a plurality of bottom electrode grooves 3;

[0083] S4, preparing a piezoelectric material layer on the upper surface of the substrate 10, wherein the piezoelectric material layer includes an ion implantation layer 4 at the bottom and a non-ion implantation layer 5 at the top, and removing the non-ion implantation layer 5 to form a piezoelectric layer 20;

[0084] S5, depositing a plurality of top electrodes 30 on the upper surface of the piezoelectric layer 20, wherein the plurality of top electrodes 30 and the plurality of bottom electrodes 40 are alternately arranged in a first horizontal direction;

[0085] S6, etching the cavity 11 on the lower surface of the substrate body 12 by deep reactive ion etching until the oxide layer 13 is exposed;

[0086] S7 , etching the oxide layer 13 with a buffered oxide etching solution, eliminating the oxide layer 13 between the cavity 11 and the piezoelectric layer 20 so that the bottom electrode 40 is exposed from the lower surface of the substrate 10 through the cavity 11 .

[0087] Specifically, step S1 is as follows: Fig. 9 As shown in process a, step S2 is as follows Fig. 9 As shown in processes b and c, step S3 is as follows Fig. 9 As shown in process d and e, step S4 is as follows Fig. 9 As shown in process f and g, step S5 is as follows Fig. 9 As shown in process h, step S6 is as follows Fig. 9 As shown in processes j, k and l, step S7 is as follows Fig. 9 As shown in process m and n.

[0088] Since the buffered oxide etching solution does not react with the piezoelectric layer 20 , it is convenient to process the oxide layer 13 separately, to prepare the bottom electrode 40 , and to separate the bottom electrode 40 from the oxide layer 13 .

[0089] Furthermore, if Fig. 9 As shown in process i, between steps S5 and S6, it also includes:

[0090] A through hole 6 is processed on the piezoelectric layer 20, and a second bus bar 41 is prepared in the through hole 6, so that the second bus bar 41 is led out from above the piezoelectric layer 20 for easy wiring.

[0091] Reference below Fig. 9 and Fig.10 Describe the method for manufacturing a Lamb wave resonator according to a specific embodiment of the present invention:

[0092] The bottom electrode groove 3 is partially etched on the silicon oxide layer 13, and the mask layer 2 is a photoresist.

[0093] The bottom electrode 40 is deposited by using techniques such as sputtering and electron beam evaporation, and the excess portion is polished by chemical mechanical polishing (CMP) to reduce the surface roughness.

[0094] The ion implantation layer 4 and the non-ion implantation layer 5 are respectively lithium niobate ion implantation regions and non-ion implantation regions. The non-ion implantation layer 5 is cut off by using a smart-cut technique to finally form a piezoelectric layer 20 .

[0095] The top electrode material is deposited on the piezoelectric layer 20 by magnetron sputtering, electron beam evaporation or the like, and the top electrode 30 is formed by maintaining a fixed relative position with the bottom electrode 40 using a lift-off technique.

[0096] A protective mask layer 2 is uniformly coated on the front surface, and a through hole 6 is etched through the piezoelectric layer 20, and the front surface process is completed.

[0097] Back-side alignment photolithography is performed to form a mask layer 2 of the cavity 11, and deep reactive ion etching (DRIE) is used to etch the polysilicon substrate body 12 until the oxide layer 13 of silicon oxide is reached and the etching is stopped.

[0098] The silicon oxide layer 13 is wet-etched using a buffered oxide etchant (BOE) solution. Since the buffered oxide etchant does not react with the piezoelectric layer 20 of lithium niobate, the etching time can be slightly prolonged to ensure that no silicon oxide remains at the bottom of the piezoelectric layer 20 .

[0099] After removing the photoresist and cleaning, a complete Lamb wave resonator is obtained.

[0100] Other structures and operations of the Lamb wave resonator 1 and the method for manufacturing the Lamb wave resonator according to the embodiment of the present invention are known to those skilled in the art and will not be described in detail here.

[0101] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0102] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A Lamb wave resonator, characterized in that: include: A substrate having a cavity therein; A piezoelectric layer, the piezoelectric layer being arranged on the upper surface of the substrate; A plurality of top electrodes, wherein the plurality of top electrodes are arranged on the upper surface of the piezoelectric layer; A plurality of bottom electrodes are provided on the lower surface of the piezoelectric layer, the plurality of bottom electrodes are exposed from the lower surface of the substrate through the cavity, and the plurality of top electrodes and the plurality of bottom electrodes are alternately spaced in a first horizontal direction.

2. The Lamb wave resonator according to claim 1, characterized in that: Each of the plurality of top electrodes and the plurality of bottom electrodes is oriented along a second horizontal direction, the first horizontal direction being perpendicular to the second horizontal direction.

3. The Lamb wave resonator according to claim 1, characterized in that: The intervals between adjacent top electrodes and bottom electrodes are equal.

4. The Lamb wave resonator according to claim 3, characterized in that: The width of each of the top electrodes and the bottom electrodes in the first horizontal direction is the same, and the width of each of the top electrodes and the bottom electrodes is 10%-50% of the interval between adjacent top electrodes and the bottom electrodes.

5. The Lamb wave resonator according to claim 1, characterized in that: It also includes a first busbar and a second busbar, the first busbar is respectively connected to the multiple top electrodes, the first busbar is arranged on the upper surface of the piezoelectric layer, the piezoelectric layer is provided with a through hole, the second busbar is respectively connected to the multiple bottom electrodes and extends from the lower surface of the piezoelectric layer through the through holes to the upper surface of the piezoelectric layer.

6. The Lamb wave resonator according to claim 1, characterized in that: The thickness of the piezoelectric layer is less than 0.5 times the wavelength of the first-order antisymmetric Lamb wave.

7. The Lamb wave resonator according to claim 1, characterized in that: The piezoelectric layer is a Z-cut or 128Y-cut single crystal lithium niobate piezoelectric film, and the top electrode and the bottom electrode are aluminum material pieces, platinum material pieces, chromium material pieces, titanium material pieces or copper material pieces.

8. The Lamb wave resonator according to claim 1, characterized in that: The shape of the cross section of the cavity parallel to the vertical direction and the first horizontal direction is a rectangle, a trapezoid or a parallelogram.

9. A method for manufacturing a Lamb wave resonator, characterized in that: The following steps are involved: providing a substrate; Processing a plurality of bottom electrode grooves on the upper surface of the substrate; preparing a plurality of bottom electrodes in a plurality of the bottom electrode grooves; Preparing a piezoelectric layer on the upper surface of the substrate; A plurality of top electrodes are prepared on the upper surface of the piezoelectric layer, wherein the plurality of top electrodes and the plurality of bottom electrodes are alternately arranged in a first horizontal direction; A cavity is processed on the lower surface of the substrate so that the bottom electrode is exposed from the lower surface of the substrate through the cavity.

10. The method for manufacturing a Lamb wave resonator according to claim 9, characterized in that: The following steps are involved: Providing a substrate, the substrate comprising a substrate body and an oxide layer located on an upper surface of the substrate body; etching a plurality of bottom electrode grooves on the oxide layer; Depositing a plurality of bottom electrodes in a plurality of the bottom electrode grooves; Preparing a piezoelectric material layer on the upper surface of the substrate, the piezoelectric material layer comprising an ion implantation layer below and a non-ion implantation layer above, and removing the non-ion implantation layer to form a piezoelectric layer; Depositing a plurality of top electrodes on the upper surface of the piezoelectric layer, wherein the plurality of top electrodes and the plurality of bottom electrodes are alternately arranged in a first horizontal direction; Etching a cavity on the lower surface of the substrate body by deep reactive ion etching until the oxide layer is exposed; The oxide layer is etched by using a buffered oxide etching solution to eliminate the oxide layer between the cavity and the piezoelectric layer so that the bottom electrode is exposed from the lower surface of the substrate through the cavity.

Images