Plate mode resonator device

Abstract

An acoustic resonator device (1) comprising a substrate (2) and a piezoelectric layer (3) such as an LN film sandwiched between a floating potential bottom electrode (6) and a pair of top electrodes (7) to which an RF voltage is applied, in which a plurality of susceptors (8) are periodically arranged between the piezoelectric layer (3) and the substrate (2) to provide mechanical stability and heat dissipation. The susceptor (8) may be arranged in alignment with nodes (12) of the acoustic amplitude of the piezoelectric layer (3), which nodes (12) are located in the region between the top electrodes, to minimize acoustic energy leakage through the susceptor (8). The substrate (2) may comprise a first substrate layer (15) of high acoustic velocity and high thermal conductivity, such as diamond, supported on a second substrate layer (16) made of wafer material.

Description

Technical Field

[0001] The invention relates to an acoustic wave resonator device, in particular to a thin film bulk acoustic wave resonator device. Background Art

[0002] Devices such as bulk acoustic wave resonators (XBAR or YBAR) that use a sub-micron thick crystalline membrane (usually lithium niobate (LN)) have significant disadvantages. The manufacturing process required for such devices is very cumbersome because the bottom side of the membrane must be open. The BAW resonator also needs to be suspended above the cavity to provide acoustic isolation. Because the membrane is very thin, these devices are fragile, and because the thermal conductivity of the film is low, these devices have poor power handling performance.

[0003] Therefore, a technical solution is needed for a resonator device similar to a classical surface acoustic wave (SAW) resonator with solid support and a heat dissipation path under the piezoelectric membrane, which is suitable for operation in the 5 GHz frequency range, has a fairly high piezoelectric coupling, and the critical dimension of the electrode CD is >0.3 μm for optical lithography.

[0004] A thin-film bulk acoustic resonator (FBAR) is a type of bulk wave resonator. If such a resonator is placed on a substrate in full mechanical contact, the resonator will not work because the acoustic energy will radiate into the substrate. Therefore, no resonance can be obtained (or a very low Q factor). To prevent this, in FBARs the membrane is either suspended over the cavity or firmly attached to a Bragg stack, which is a system of alternating high and low acoustic impedances consisting of many λ / 4 layers. This multilayer Bragg stack acts as a strong reflector and does not allow the bulk waves to radiate into the substrate.

[0005] The same problems still exist in YBAR devices, that is, the sub-micron-thick membrane suspended over the cavity is very fragile, and the thermal conductivity of the crystalline membrane (LN) is low, so the power handling of the device is poor. In addition, the fabrication process of the Bragg stack is very complex. Summary of the invention

[0006] An object of the present invention is to provide an improved acoustic wave resonator device which overcomes or at least reduces the above-mentioned problems.

[0007] The above and other objects are achieved by the features of the independent claims. Other implementations are apparent from the dependent claims, the description and the drawings.

[0008] According to a first aspect, an acoustic wave resonator device is provided, wherein a piezoelectric layer (e.g., LN membrane) sandwiched between a pair of top electrodes and a floating bottom electrode is attached to a substrate via a base to provide a space between the substrate and the piezoelectric layer. The bottom electrode portion is limited to an overlap portion with the top electrode.

[0009] This arrangement provides a solid mechanical support for the piezoelectric layer, improves heat dissipation through spacing, thereby increasing power handling capability, and provides sufficiently large piezoelectric coupling. The device according to the present invention solves the fragility problem of existing YBAR resonators using sub-micron thick membranes by attaching the membrane (i.e., piezoelectric layer) to a solid thick substrate through a base.

[0010] In a possible implementation of the first aspect, the bottom electrode is provided with a floating potential, and the piezoelectric layer comprises a plurality of top electrodes arranged on the top surface. Adjacent top electrodes of the plurality of top electrodes are arranged with opposite polarities and a pitch p, and the pitch p is defined by the conventional distance between the centers of the adjacent top electrodes. This provides an acoustic wave resonator arrangement that is scalable in multiple directions and can be implemented in devices of different sizes as required. This arrangement also provides the possibility of changing or tuning the resonant frequency by changing the pitch and electrode geometry.

[0011] In another possible implementation of the first aspect, the size of the pitch p is determined to satisfy p <V diam / V LN *d LN Conditions, where V diam corresponds to the transverse acoustic velocity in the substrate, V LN corresponds to the transverse acoustic velocity in the piezoelectric layer, d LN corresponds to the thickness of the piezoelectric layer. Since no bulk waves are radiated into the substrate, the Q factor of the resonator is high, so this arrangement can operate with minimal losses at the operating frequency Fr of the resonator.

[0012] In another possible implementation of the first aspect, the plurality of top electrodes include an interdigitated electrode (IDE) periodic system, wherein the IDE periodic system is arranged on the top surface and alternately connected to bus bars, and this arrangement can apply an AC voltage to the electrodes.

[0013] In one embodiment, the busbars are arranged on the top surface. In another embodiment, the busbars are arranged directly on the substrate, being available only at the bottom electrode site before the overlap site of the top electrode.

[0014] In one embodiment, the bus bar includes two layers made of different metallic materials.

[0015] In one embodiment, a dielectric layer is disposed between the piezoelectric layer and the bus bar, the dielectric layer comprising SiO2 or SiN.

[0016] In another possible implementation of the first aspect, the piezoelectric layer includes a groove, wherein the groove is arranged in an area of ​​the piezoelectric layer not covered by the top electrode, so that the top electrode can vibrate more freely, thereby increasing piezoelectric coupling.

[0017] In various embodiments, the trench depth may range from zero to the full thickness of the piezoelectric layer to achieve maximum coupling of the resonator. In one embodiment, the trench depth is greater than 1 / 3 of the thickness of the piezoelectric layer.

[0018] In another possible implementation of the first aspect, the piezoelectric layer includes a piezoelectric material arranged to be intermittently sandwiched between the multiple pairs of top electrodes and the bottom electrodes, and the grooves extend across the entire width and depth of the piezoelectric layer between the top electrodes.

[0019] In another possible implementation of the first aspect, the plurality of pedestals are arranged to be aligned with nodes of the acoustic wave amplitude of the piezoelectric layer to minimize acoustic energy leaking through the pedestals, wherein the nodes are located in an area of ​​the piezoelectric layer not covered by the top electrode.

[0020] In another possible implementation manner of the first aspect, the plurality of bases are periodically arranged between the piezoelectric layer and the substrate to provide sufficient mechanical stability while being able to dissipate heat.

[0021] In another possible implementation of the first aspect, the plurality of bases are integral with the substrate or made of the same material as the substrate and are formed as ridges between the grooves in the substrate, thereby increasing structural integrity and also simplifying the manufacturing process.

[0022] In another possible implementation manner of the first aspect, the plurality of bases are at least partially embedded in grooves arranged on the bottom surface of the piezoelectric layer, which further increases the structural integrity of the acoustic wave resonator device.

[0023] In a possible embodiment, the piezoelectric layer includes lithium niobate (LN), lithium tantalate (LT), AlN, AlScN or any other suitable piezoelectric material.

[0024] In another possible implementation of the first aspect, the piezoelectric layer is arranged in a rotated Y-cut, an X-cut 30° Y-propagation, an X-cut or other suitable crystal orientations to provide large coupling of the piezoelectric material.

[0025] In a possible embodiment, at least one of the bottom electrode and the top electrode is made of Al, Cu, Mo, Pt, W, Au or alloys thereof.

[0026] In a possible embodiment, the plurality of bases include a material with high thermal conductivity such as Al, Cu, Au, Si, SiO2, SiC, BN or Si3N4. The base with such high thermal conductivity can provide good heat dissipation performance.

[0027] In another possible implementation manner of the first aspect, the piezoelectric layer is mechanically attached to the substrate at a distal end of the piezoelectric layer to make the structure of the acoustic wave resonator device more robust.

[0028] In another possible implementation of the first aspect, the substrate includes a first substrate layer, wherein the first substrate layer includes a high acoustic wave velocity and high thermal conductivity material, such as diamond, SiC, BN or Si. The high thermal conductivity of the substrate can achieve excellent power handling capabilities. The problem of overheating and low power handling of the resonator device is solved by dissipating heat to the substrate through the base in a direction perpendicular to the membrane, while in the YBAR device, the heat is mainly discharged along the electrode. Through the high acoustic velocity substrate, body acoustic wave radiation is avoided and the Q factor of the resonator is improved.

[0029] In another possible implementation manner of the first aspect, the first substrate layer is arranged to have a thickness d S1 is greater than the thickness of the piezoelectric layer to avoid bulk acoustic radiation and improve the Q factor of the resonator device.

[0030] In one embodiment, the thickness of the first substrate layer is 4 to 20 times the thickness of the piezoelectric layer.The first substrate layer is so thick relative to the piezoelectric layer that bulk waves cancel each other due to destructive interference of waves in opposite phases.

[0031] In another possible implementation of the first aspect, the substrate includes a second substrate layer, wherein the second substrate layer is arranged on a side of the first substrate layer opposite to the base, and is used to support the first substrate layer, and the second substrate layer is preferably arranged to have a thickness of d S2 greater than the thickness d of the first substrate layer S1 The second substrate layer includes wafer materials such as Si, SiC, sapphire, quartz or glass.

[0032] According to a second aspect, there is provided a method for manufacturing an acoustic wave resonator device, the method comprising the following steps:

[0033] forming a substrate, wherein the substrate comprises a first substrate layer and a supporting second substrate layer, the first substrate layer comprising a high acoustic wave velocity and high thermal conductivity material;

[0034] forming a plurality of pedestals on the substrate;

[0035] forming a second substrate, wherein the second substrate comprises a piezoelectric layer having a bottom surface and a top surface, and is arranged on a support layer, preferably on a Si wafer;

[0036] Disposing a bottom electrode on the bottom surface of the piezoelectric layer;

[0037] wafer-to-wafer bonding of the bottom electrode;

[0038] removing the support layer of the second substrate;

[0039] A plurality of pairs of top electrodes are disposed on the top surface of the piezoelectric layer.

[0040] Forming an acoustic wave resonator device according to these steps can provide a sufficiently robust acoustic wave resonator, with high power handling capabilities due to heat dissipation through the spacing, and can provide sufficiently large piezoelectric coupling, while also enabling a relatively simple and scalable manufacturing process. The method can also use common SAW technology in the 5GHz frequency range and can be manufactured using optical lithography.

[0041] These and other aspects will be apparent from one or more of the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In the following detailed description of the present invention, various aspects, embodiments and implementations will be described in more detail in conjunction with exemplary embodiments shown in the accompanying drawings, in which:

[0043] Figure 1 shows a cross section of an acoustic wave resonator device provided by an example of an embodiment of the present invention;

[0044] Figure 2 shows a cross section of an acoustic wave resonator device provided by another example of an embodiment of the present invention;

[0045] Figure 3 The figure shows the resonant vibration mode (SH1) of the acoustic wave resonator device in the Y direction provided by another example of the embodiment of the present invention;

[0046] Figure 4 shows a cross section of an acoustic wave resonator device provided by another example of an embodiment of the present invention;

[0047] Figure 5 shows a cross section of an acoustic wave resonator device provided by another example of an embodiment of the present invention;

[0048] Fig. 6A and Figure 6B The effect of different piezoelectric film crystal orientations on the piezoelectric coupling of an acoustic wave resonator device provided by another example of an embodiment of the present invention is shown;

[0049] Figure 7 The effect of the groove depth on the piezoelectric coupling in different embodiments of the acoustic wave resonator device provided by the examples of the present invention is shown;

[0050] Figure 8 The effect of pitch on resonant frequency in different embodiments of acoustic wave resonator devices provided by examples of the present invention is shown;

[0051] Fig. 9A and Fig. 9B 2D and 3D simulation results of optimized configurations of acoustic wave resonator devices suitable for practical optical lithography provided by examples of the present invention are shown. DETAILED DESCRIPTION

[0052] In the following detailed description, many specific details are set forth by way of example to facilitate a comprehensive understanding of the related invention. However, it should be understood by those skilled in the art that the present invention can be practiced without such details. In other examples, well-known methods, procedures, systems, components and / or circuits are described in a relatively general manner but not in detail to avoid unnecessary understanding problems for various aspects of the present invention.

[0053] The structure of the proposed acoustic wave resonator device 1 is multi-layered and periodic.

[0054] Figure 1 One period of the structure of the acoustic wave resonator device 1 is shown. For example, for the device 1, this period can be multiplied to have hundreds of such structural periods, such as Figure 2 The partial cross section is shown.

[0055] The acoustic wave resonator device 1 comprises a substrate 2 and a resonator layer, which is a piezoelectric layer 3 made of lithium niobate (LN), lithium tantalate (LT), AlN, AlScN or any other suitable piezoelectric material and comprises a bottom surface 4 and a top surface 5. The piezoelectric layer 3 can be arranged in a rotated Y-cut, an X-cut 30° Y-propagation, an X-cut or other suitable crystal orientation to provide a large coupled piezoelectric module k of the piezoelectric material. 34 2 .

[0056] A bottom electrode 6 with floating potential is arranged on the bottom surface 4, and at least a pair of top electrodes 7 is arranged on the top surface 5. The bottom electrode 6 and / or the top electrode 7 are made of Al, Cu, Mo, Pt, W, Au or their alloys.

[0057] Preferably, the bottom electrode covers a portion opposite to the top electrode, where the bottom electrode and the top electrode overlap in the aperture direction (y). The bottom electrode does not extend under the bus bar.

[0058] Between the bottom electrode 6 and the substrate 2, a plurality of pedestals 8 are also arranged to provide spacing between the piezoelectric layer 3 and the substrate 2. The pedestals 8 can be made of a metal with high thermal conductivity such as Al, Cu, Au or dielectric Si, SiO2, SiC, BN or Si3N4. The pedestals 8 are periodically placed between the bottom surface 4 of the piezoelectric layer 3 and the upper layer of the substrate 2, thereby providing mechanical stability and good heat dissipation from the piezoelectric layer 3 to the substrate 2.

[0059] The substrate 2 comprises a first substrate layer 15 made of a material with high acoustic wave velocity and high thermal conductivity, such as diamond or other materials close to diamond in mechanical terms (the velocity of all bulk acoustic waves is high). For example, such materials may be silicon carbide (SiC) or boron nitride (BN) or Si. The first substrate layer 15 is supported on a second substrate layer 16 made of a wafer material such as Si, SiC, sapphire, quartz or glass.

[0060] For example, the acoustic velocity of the substrate 2 may be twice the acoustic velocity of the piezoelectric layer 3 .

[0061] like Figure 2 As shown, a plurality of pairs of top electrodes 7 may be provided on the top surface 5 , with adjacent top electrodes 7 in the plurality of top electrodes 7 being arranged with opposite polarities and a pitch p. The pitch is defined as the general distance between the centers of adjacent top electrodes 7 .

[0062] If a high acoustic velocity material such as diamond is used, the pitch p can be determined to be approximately p<(2.4–3.0)d LN , where dLN corresponds to the thickness of the piezoelectric layer 3. These dimensions make it possible to avoid the radiation of bulk acoustic waves into the underlying substrate.

[0063] The size of the piezoelectric layer 3 can be determined to be approximately d LN =λ LN / 2. The main resonant frequency of the SH1 mode is based on d LN and pitch p, where f r =((v t1 / 2d LN ) 2 +(v t2 / 2p)2 ) 1 / 2 , where v t is the transverse acoustic velocity in the piezoelectric layer 3, therefore, the resonance frequency can be controlled to a certain extent by the pitch p.

[0064] In one embodiment, the piezoelectric layer 3 is a Y-cut LN film, where the transverse (perpendicular electric field) excites shear acoustic waves displaced perpendicular to the barrier. The resonant frequency corresponds to a film thickness of the piezoelectric layer 3 equal to λ / 2 (half the wavelength). The main resonant mode is similar to the SH1 plate mode.

[0065] The plurality of top electrodes 7 may be arranged as a periodic system of interdigitated electrodes (IDE) arranged on the top surface 5 ( Figure 1 ) and are alternately connected to bus bars arranged for applying AC voltage. In one embodiment, the bus bars are arranged on the top surface 5. In another embodiment, the bus bars are arranged directly on the substrate 2. In one embodiment, the bus bars include two layers made of different metal materials.

[0066] In one embodiment, a dielectric layer is arranged between the piezoelectric layer 3 and the busbars, the dielectric layer comprising SiO2 or SiN.

[0067] The bottom electrode 6 is a metal layer used as a floating potential for the YBAR structure, providing a vertical electric field together with the top electrode 7. The metal can be Al, with a relatively small thickness, such as 50nm. A larger thickness may trap more acoustic energy in the inert metal, thereby reducing piezoelectric coupling. If many such resonators are used in a "ladder" filter, the bottom metal electrode 6 of each resonator must be isolated rather than connected. The small resonators generated by the top electrode 7 and the bottom electrode 6 are connected in series through the bottom electrode 6. The top electrode 7 can have an alternating potential of V, 0, V, 0, etc. In this case, the floating bottom electrode 6 is not connected to any external voltage source, and is affected by the parasitic capacitance of the bus bars and other conductors to obtain a potential close to V / 2.

[0068] The first substrate layer 15 may be a relatively thin layer, for example, with a thickness d S1 Only the thickness d of the piezoelectric layer 3 LN However, the first substrate layer 15 needs to be thick enough relative to the piezoelectric layer 3 so that the body waves generated by each part into the substrate cancel each other due to the destructive interference of the waves with opposite phases. The second substrate layer 16 can be arranged with a thickness of d S2 Greater than the thickness d of the first substrate layer 15 S1 , and is used only for mechanical support of the top layer and for heat dissipation. In layer 16, no acoustic waves propagate near the resonant and anti-resonant frequencies of the resonator.

[0069] The size of the pitch p is determined by satisfying p<(V diam / V LN *d LN ) condition, providing minimum loss at the resonator operating frequency Fr, where V diam corresponds to the transverse acoustic velocity in the substrate 2, V LN corresponds to the transverse acoustic velocity in the piezoelectric layer 3, d LN Corresponds to the thickness of the piezoelectric layer 3 .

[0070] In LN, the speed of sound V SH1 It may be about 4000 m / s, and up to 9600 m / s in a high acoustic velocity substrate. Therefore, in the case of a diamond substrate, the pitch needs to be greater than the thickness d of the piezoelectric layer 3. LN This makes the pitch p < 1.2 μm at 5 GHz suitable for fabrication using optical lithography.

[0071] The relatively small pitch (by comparison, the pitch of an XBAR can be around 20 times larger) results in a reduction in parasitic modes. This arrangement also offers the possibility of changing or tuning the resonant frequency by varying the pitch and electrode geometry.

[0072] Figure 3 The amplitude distribution of the vibration displacement in the piezoelectric layer 3 and the electrodes 6 and 7 of the main resonant mode SH1 mode at the resonant frequency is shown. Due to the vertical electric field generated by the top and bottom electrodes of the structure and the selection of the cutout of the piezoelectric layer 3 with a higher piezoelectric module e34 value, the main vibration displacement of the SH1 mode is in the Y direction (perpendicular to Figure 3 The base 8 acts as a solid support and does not participate (or minimally participates) in the resonant vibration. The high-speed substrate 2 avoids body wave radiation and energy leakage downward. The main acoustic energy is trapped in the piezoelectric layer 3, providing a high Q factor of the resonator.

[0073] like Figure 3 As shown, a plurality of pedestals 8 are arranged to align with nodes 12 of the acoustic wave amplitude of the piezoelectric layer 3 to minimize acoustic energy leaking through the pedestals 8, the nodes 12 being located in the region of the piezoelectric layer 3 not covered by the top electrode.

[0074] like Figure 4 As shown, the piezoelectric layer 3 can be arranged to have grooves 11 in the area of ​​the piezoelectric layer 3 not covered by the top electrode 7, so that the top electrode 7 can vibrate more freely, thereby increasing the piezoelectric coupling. In different embodiments, the groove depth can be from zero to the entire thickness of the piezoelectric layer 3 (such as Figure 4In the example shown, the piezoelectric layer 3 includes a piezoelectric material arranged to be intermittently sandwiched between a plurality of pairs of top electrodes 7 and bottom electrodes 6, and the grooves 11 extend over the entire width and depth of the piezoelectric layer 3 between the top electrodes 7.

[0075] like Figure 5 As shown, the plurality of pedestals 8 may be integral with the substrate 2 or made of the same material as the substrate 2, and may be formed as ridges between the grooves 11 in the substrate 2. In some embodiments, as also shown in FIG. Figure 5 As shown, a plurality of pedestals 8 are at least partially embedded in recesses 14 arranged on the bottom surface 4 of the piezoelectric layer 3. In this case, the parts of the bottom electrode must remain electrically connected.

[0076] In one embodiment (not shown), the piezoelectric layer 3 may also be directly connected to the substrate 2 at the distal end of the piezoelectric layer 3 .

[0077] Fig. 6A and Figure 6B The admittance curves showing the effect of the crystal orientation of the piezoelectric layer 3 of the resonator on the piezoelectric coupling over one period (arbitrary displacement on the vertical axis) are shown on a logarithmic scale (log10(abs(Y)) and log10(real(Y))). Based on the structure and the resonant mode (SH1), the X-cut 30° relative to the Y crys The propagated LN provides greater piezoelectric coupling.

[0078] The graph of 6A shows that the common Y-cut LN (Euler angles [0 90 0]) provides a resonant frequency of 6.03 GHz and an anti-resonant frequency of 6.78 GHz, with a piezoelectric coupling of 24.52%; while the graph of 6B shows that the optimal X-cut 30° Y-propagation LN (Euler angles [90 90 30]) cut provides a resonant frequency of 5.94 GHz and an anti-resonant frequency of 7.02 GHz, with a piezoelectric coupling of 32.89%.

[0079] Figure 7 The effect of the groove depth of the piezoelectric layer 3 on the resonant piezoelectric coupling is shown, where the thickness d LN = 300nm. The groove can be used for greater piezoelectric coupling of the structure, as Figure 4 The grooves allow the top electrode 7 and the underlying piezoelectric layer 3 to vibrate more freely, thereby increasing the amplitude of the vibration and the piezoelectric coupling.

[0080] Figure 7 It is also shown that as long as the groove depth is greater than the thickness d of the piezoelectric layer 3 LNIf the groove depth is 1 / 3 of the original depth, it can provide a good piezoelectric coupling performance of more than 40%. As the groove depth increases, the piezoelectric coupling also increases, and the maximum piezoelectric coupling can reach 45%.

[0081] Figure 8 The effect of the pitch on the resonant frequency of the structure is shown. The graph shows that the larger the pitch, the lower the resonant and anti-resonant frequencies. Although the resonant frequency is mainly based on the thickness d of the piezoelectric layer 3 LN , but when λ is approximately equal to 2d LN When the thickness of the piezoelectric layer 3 is constant, the resonant frequency can be tuned by changing the pitch p or by changing the geometry of the top electrode 7 (for example, by changing the width of the top electrode 7 or by constructing the top electrode 7 with a trapezoidal cross-sectional shape).

[0082] like Fig. 9A and Fig. 9B It is further shown that by optimizing the configuration parameters, a large coupling (41%) of parasitic-free modes can be achieved in a high frequency (4.5 GHz to 6 GHz) configuration, where the critical dimension CD>320 nm is suitable for practical optical lithography, which is confirmed by 2D and 3D FEM simulations. This shows the effectiveness and correctness of the model in further practical production.

[0083] Exemplary model parameters used for simulation are:

[0084] - Pitch: 0.8um

[0085] - Piezoelectric layer (film) thickness: 325nm

[0086] - Base height: 300nm

[0087] -Top electrode (Al IDT) thickness: 50nm

[0088] - Bottom electrode (Al) thickness: 40nm

[0089] -IDT metallization ratio (MR): 0.4

[0090] -Base metallization rate: 0.4

[0091] -X cut 30°Y spread LN

[0092] - Groove depth 275nm

[0093] An exemplary method for manufacturing an acoustic wave resonator device 1 as shown in the above figure may include a first step of forming a substrate 2 on a supporting second substrate layer 16 (wafer), wherein the substrate 2 includes a first substrate layer 15 made of a material with high acoustic wave velocity and high thermal conductivity such as diamond.

[0094] Next, a plurality of susceptors 8 are formed on the substrate 2 .

[0095] On the support layer, preferably on a Si wafer, a second (temporary) substrate is arranged, wherein the second (temporary) substrate comprises a piezoelectric layer 3 having a bottom surface 4 and a top surface 5 , to which the temporary substrate is attached.

[0096] A bottom electrode 6 is arranged on the bottom surface 4 of the piezoelectric layer 3 , and then the bottom electrode 6 and the electrode structure 8 are wafer-to-wafer bonded.

[0097] The supporting layer of the second substrate is then removed, and then a plurality of pairs of top electrodes 7 are arranged on the top surface 5 of the piezoelectric layer 3 .

[0098] It will be understood that when a unit, module, or engine is referred to as being "on," "connected to," or "coupled to" another unit, module, or engine, the unit, module, or engine may be directly on, connected to, coupled to, or in communication with another unit, module, or engine, or there may be intermediate units, modules, or engines, unless the context clearly indicates otherwise. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0099] Various aspects and implementations have been described herein in conjunction with various embodiments. However, those skilled in the art, when practicing the subject matter for which protection is requested, can understand and implement other variations of the disclosed embodiments by studying the drawings, the present invention and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and "one" or "an" does not exclude multiple. A single processor or other unit can satisfy the functions of several items described in the claims. The listing of some measures in mutually different dependent claims does not mean that the combination of these measures cannot be used to obtain advantages. The computer program can be stored or distributed on a suitable medium (e.g., an optical storage medium or solid-state medium provided together with other hardware or as part of other hardware), and can also be distributed in other forms (e.g., via the Internet or other wired or wireless telecommunications systems).

[0100] Reference signs used in the claims should not be construed as limiting the scope.

Claims

1. An acoustic wave resonator device (1), characterized in that: include: Substrate (2); The piezoelectric layer (3) comprises a bottom surface (4) and a top surface (5), A bottom electrode (6) is arranged on the bottom surface (4), At least one pair of top electrodes (7) arranged on the top surface (5); A plurality of pedestals (8) are arranged between the bottom electrode (6) and the substrate (2) to provide spacing between the piezoelectric layer (3) and the substrate (2).

2. The acoustic wave resonator device (1) according to claim 1, characterized in that: The bottom electrode (6) is set with a floating potential, and the piezoelectric layer (3) includes a plurality of top electrodes (7) arranged on the top surface (5), wherein adjacent top electrodes (7) among the plurality of top electrodes (7) are arranged with opposite polarities and a pitch p, and the pitch p is defined by a regular distance between the centers of the adjacent top electrodes (7).

3. The acoustic wave resonator device (1) according to claim 2, characterized in that: The size of the pitch p is obtained by satisfying p <V diam / V LN *d LN condition, providing minimum loss at the resonator operating frequency Fr, where V diam Corresponding to the transverse acoustic velocity in the substrate (2), V LN corresponds to the transverse acoustic velocity in the piezoelectric layer (3), d LN Corresponding to the thickness of the piezoelectric layer (3).

4. The acoustic wave resonator device (1) according to claim 2 or 3, characterized in that: The plurality of top electrodes (7) include an interdigitated electrode (IDE) periodic system, wherein the IDE periodic system is arranged on the top surface (5) and is alternately connected to bus bars arranged for applying an AC voltage.

5. The acoustic wave resonator device (1) according to any one of claims 2 to 4, characterized in that: The piezoelectric layer (3) comprises a groove (11), wherein the groove (11) is arranged in an area of ​​the piezoelectric layer (3) not covered by the top electrode (7), so that the top electrode (7) can vibrate more freely, thereby increasing the piezoelectric coupling.

6. The acoustic wave resonator device (1) according to claim 5, characterized in that: The piezoelectric layer (3) comprises a piezoelectric material arranged to be intermittently sandwiched between the plurality of pairs of top electrodes (7) and the bottom electrode (6), and the grooves (11) extend across the entire width and depth of the piezoelectric layer (3) between the top electrodes (7).

7. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that The plurality of pedestals (8) are arranged to be aligned with nodes (12) of the acoustic wave amplitude of the piezoelectric layer (3) to minimize acoustic energy leaking through the pedestals (8), wherein the nodes (12) are located in the region of the piezoelectric layer (3) not covered by the top electrode.

8. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that The plurality of bases (8) are periodically arranged between the piezoelectric layer (3) and the substrate (2) to provide mechanical stability and heat dissipation.

9. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that The plurality of pedestals (8) are integral with the substrate (2) or are made of the same material as the substrate (2), and are formed as ridges between the grooves (11) in the substrate (2).

10. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that The plurality of bases (8) are at least partially embedded in grooves (14) arranged on the bottom surface (4) of the piezoelectric layer (3).

11. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that The piezoelectric layer (3) comprises lithium niobate (LN), lithium tantalate (LT), AlN, AlScN or any other suitable piezoelectric material.

12. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that The piezoelectric layer (3) is arranged in a rotated Y-cut, an X-cut 30° Y-propagation, an X-cut or other suitable crystal orientations to provide a large coupling of the piezoelectric material (piezoelectric module k 34 2 ).

13. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that At least one of the bottom electrode (6) and the top electrode (7) is made of Al, Cu, Mo, Pt, W, Au or an alloy thereof.

14. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that The plurality of pedestals (8) include a high thermal conductivity material such as Al, Cu, Au or a dielectric such as Si, SiO2, SiC, BN or Si3N4.

15. The acoustic wave resonator device (1) according to claim 9, characterized in that The piezoelectric layer (3) is mechanically attached to the substrate (2) at a distal end of the piezoelectric layer (3).

16. The acoustic wave resonator device (1) according to any one of the preceding claims, characterized in that The substrate (2) comprises a first substrate layer (15), wherein the first substrate layer (15) comprises a material with high acoustic wave velocity and high thermal conductivity, such as diamond, SiC or BN.

17. The acoustic wave resonator device (1) according to claim 16, characterized in that The first substrate layer (15) is arranged with a thickness d S1 Greater than the thickness d of the piezoelectric layer (3) LN , preferably the thickness d of the piezoelectric layer (3) LN 4 to 20 times.

18. The acoustic wave resonator device (1) according to claim 16 or 17, characterized in that The substrate (2) comprises a second substrate layer (16), wherein the second substrate layer (16) is arranged on a side of the first substrate layer (15) opposite to the base (8) for supporting the first substrate layer (15), and the second substrate layer (16) is preferably arranged to have a thickness of d S2 greater than the thickness d of the first substrate layer (15) S1 The second substrate layer (16) includes wafer materials such as Si, SiC, sapphire, quartz or glass.

19. A method for manufacturing an acoustic wave resonator device (1), characterized in that The following steps are involved: Forming a substrate (2), wherein the substrate (2) comprises a first substrate layer (15) and a supporting second substrate layer (16), the first substrate layer (15) comprising a material with high acoustic wave velocity and high thermal conductivity; forming a plurality of bases (8) on the substrate (2); forming a second substrate, wherein the second substrate comprises a piezoelectric layer (3) having a bottom surface (4) and a top surface (5), arranged on a support layer, preferably on a Si wafer; A bottom electrode (6) is provided on the bottom surface (4) of the piezoelectric layer (3); Wafer-to-wafer bonding of the bottom electrode (6); removing the support layer of the second substrate; A plurality of pairs of top electrodes (7) are arranged on the top surface (5) of the piezoelectric layer (3).

Images