Acoustic resonator equipment utilizing Lamb wave A1 mode

Abstract

The present disclosure relates to an acoustic resonator device utilizing acoustic Lamb waves in a piezoelectric layer (103). The resonator device comprises a dielectric substrate (101); an IDT structure including a conductive first electrode (102a) connected to the first bus bar and a conductive second electrode (102b) connected to the second bus bar, where the first electrode and the second electrode are periodically and alternately disposed one by one on the dielectric substrate; and the piezoelectric layer (103) and the dielectric substrate are arranged in parallel at an interval. The piezoelectric layer is disposed on the first electrode and the second electrode of the IDT structure, and is disposed on the first bus bar and the second bus bar. The IDT structure is located between the substrate and the piezoelectric layer and may be mechanically fixedly connected thereto for converting an alternative voltage to the acoustic lamb wave in the piezoelectric layer, thereby generating an electrical resonance at a frequency corresponding to a thickness acoustic shear wave resonance in the piezoelectric layer.

Description

Technical Field

[0001] The present disclosure relates to an acoustic resonator device. The acoustic resonator device includes a piezoelectric layer disposed on a dielectric substrate, and includes an interdigital transducer (IDT) structure disposed between the dielectric substrate and the piezoelectric layer, wherein the IDT structure can be fixedly connected to both the piezoelectric layer and the dielectric substrate for resonantly exciting an acoustic Lamb wave A1 mode in the piezoelectric layer. Background Art

[0002] Recently, an excited bulk acoustic resonator (XBAR) device has been proposed, which uses a sub-micron thick crystalline piezoelectric film (for example, made of lithium niobate (LN)) as the piezoelectric layer. The device can operate in the 5 GHz frequency range, has a critical dimension (CD) greater than 0.3 μm, and can be manufactured using optical lithography. However, XBAR devices also have some disadvantages. For example, the manufacturing of XBAR devices is very difficult because the bottom side of the piezoelectric film is open and free. Specifically, the piezoelectric film is suspended over a cavity for acoustic isolation. Therefore, XBAR devices are fragile, especially because the piezoelectric film is very thin. In addition, due to the low thermal conductivity of the lithium niobate material and the sub-micron thickness of the piezoelectric film, the power handling performance of the XBAR device is poor, and the heat can only be discharged from the film to the sides of the cavity. Thin and long IDT electrodes must be used to convert the AC voltage into acoustic waves in the piezoelectric film. These IDT electrodes have higher resistivity and are less able to remove the generated heat, increasing losses and causing overheating of the XBAR device.

[0003] Exemplary XBAR devices include thicker electrodes (even thicker than the piezoelectric layer itself) in an attempt to improve power handling performance. However, such thick electrodes can create additional acoustic resonances, making the device more lossy, reducing its Q factor, and causing unacceptable perturbations to the admittance curve.

[0004] Another exemplary XBAR device includes a base supporting the suspended film in an attempt to reduce the fragility of the device. However, this only partially overcomes the above-mentioned disadvantages. Specifically, the heat-generating IDT electrode is separated from the substrate of the device by the piezoelectric film, which has a relatively low thermal conductivity. In addition, the thermal conductivity of the base is also limited. Therefore, the power handling performance of the exemplary XBAR device is still not optimal. In addition, the manufacturing of the exemplary XBAR device is very difficult because both sides of the piezoelectric film are used, one side for connecting to the base and the other side for applying the IDT electrode. Summary of the invention

[0005] In view of the above, the present disclosure is directed to providing an improved acoustic resonator device. The goal is to overcome the above-mentioned shortcomings of the XBAR device. Another goal is that the acoustic resonator device also has greater mechanical robustness than the XBAR device. For example, it is desirable to use a strong thick substrate to stabilize the device. It is yet another goal to improve the power handling performance of the acoustic resonator device compared to the XBAR device. The acoustic resonator device of the present disclosure should be suitable for operation in the 5 GHz frequency range. In addition, the critical dimension (CD) of the IDT electrode should be greater than 0.3 μm.

[0006] These and other objects are achieved by the disclosed solutions described in the independent claims. Advantageous implementations are further defined in the dependent claims.

[0007] One aspect of the present disclosure provides an acoustic resonator device, comprising: a dielectric substrate; an IDT structure, comprising a plurality of conductive first electrodes connected to a first bus bar and a plurality of conductive second electrodes connected to a second bus bar, wherein the first electrodes and the second electrodes are periodically and alternately arranged one by one on a surface of the dielectric substrate; a piezoelectric layer, spaced apart from and arranged in parallel with the surface of the dielectric substrate; wherein the piezoelectric layer is arranged on the first and second electrodes of the IDT structure, and on the first and second bus bars; wherein the IDT structure is used to convert an electrical signal into an acoustic Lamb wave in the piezoelectric layer.

[0008] The dielectric substrate may be non-piezoelectric or weakly piezoelectric. For example, the dielectric substrate may include a weakly piezoelectric material, such as quartz.

[0009] The IDT structure can be produced on the dielectric substrate and arranged between the dielectric substrate and the piezoelectric layer. The electrode of the IDT structure can contact the piezoelectric layer without any intermediate medium so as to produce good thermal coupling with the piezoelectric layer. The electrode of the IDT structure can be mechanically and / or fixedly connected to the piezoelectric layer. The electrode of the IDT can be connected to the dielectric substrate through a viscous medium or a metal layer. However, the electrode and the dielectric substrate can also produce good thermal coupling. The bus bar is used to provide a voltage, specifically, to provide an AC voltage between the first electrode and the second electrode. The AC voltage can be converted by the electrode into vibration of the piezoelectric layer, thereby exciting the acoustic Lamb wave in the piezoelectric layer. The resonant frequency can be basically determined by the thickness of the piezoelectric layer.

[0010] The acoustic resonator device has several advantages. Since the thin piezoelectric layer is disposed on the electrode of the IDT structure, it is supported by the electrode of the IDT structure and the bus bar, so the device has a stronger mechanical strength than a conventional XBAR device. Specifically, the portion of the piezoelectric layer that overlaps the bus bar can be bonded to the bus bar to improve the mechanical stability of the device. In addition, since the heat generated by the IDT electrode can be directly discharged to the dielectric substrate through the large area bottom side of the electrode, and the dielectric substrate can have a high thermal conductivity, the power handling performance of the acoustic resonator device is significantly improved compared to a conventional XBAR device. Compared to a conventional XBAR device, since the IDT electrode of the acoustic resonator device can be very thick, the resistance loss can also be reduced. In addition, since the IDT electrode is fixed to the dielectric substrate, the parasitic vibration or resonance of the IDT electrode can be reduced.

[0011] The acoustic resonator device described in the present disclosure can be used in a "ladder" filter network. For example, to provide a low-loss broadband filter for 5G mobile devices, the resonator device preferably has a low impedance (typically less than 1Ohm) at resonance and a high impedance (for example, greater than 1000Ohm) at anti-resonance. This can be achieved by the acoustic resonator device described in the present disclosure. In addition, the relative frequency gap (RaR) between resonance and anti-resonance is preferably greater than 10%, or even up to 25%, and the static capacitance at the operating frequency is approximately j*50Ohm. This can also be achieved by the acoustic resonator device described in the present disclosure. It is worth noting that parasitic disturbances caused by other propagation modes or resonance modes are only tolerated at low levels.

[0012] In one implementation of the aspect, the acoustic Lamb wave includes a Lamb wave A1 mode and / or a Lamb wave A3 mode.

[0013] It is worth noting that although it is theoretically possible to excite Lamb modes of n = 5 or higher, this may result in 2 In any case, the acoustic resonator devices described in the present disclosure can utilize the fundamental (n=1), second (n=2 with deposited additional layers) and third (n=3) order of the acoustic Lamb waves A1, quasi S2 and A3 in the piezoelectric layer.

[0014] In one implementation of the aspect, the electrode of the IDT structure is connected to the piezoelectric layer at a location of an amplitude node of the acoustic Lamb wave.

[0015] Thus, the vibration energy leaking into the dielectric substrate is reduced. The electrodes support the generation of the acoustic Lamb waves in the piezoelectric layer. The piezoelectric layer can vibrate freely according to the acoustic Lamb waves, and the piezoelectric layer is connected to the substrate through electrodes located at the vibration nodes or places where the vibration amplitude is minimum and zero.

[0016] Alternatively, the vibration between the electrodes can be described as a standing wave resonance, whose resonant frequency is determined by the film thickness d P =λ / 2 (corresponding to A1 Lamb mode) or d P =3 / 2*λ (corresponding to A3 mode). Therefore, the resonance frequency is mainly determined by the thickness of the piezoelectric layer and may have only a weak dependence on the pitch p between the electrodes.

[0017] In an implementation of the aspect, the dielectric substrate is made of diamond, silicon carbide or boron nitride.

[0018] Therefore, the dielectric substrate uses a material with a high acoustic wave velocity. The dielectric substrate is also mechanically strong and has good thermal conductivity. Other similar materials such as sapphire, YAG, etc. can be used.

[0019] In an implementation of the aspect, the thermal conductivity of the dielectric substrate is higher than 100 W / m*K.

[0020] For example, the thermal conductivity may be equal to or higher than 300 W / m*K. The thermal conductivity of the piezoelectric layer may be 1 to 10 W / m*K, for example the thermal conductivity of a lithium niobate layer is about 4.2 W / m*K. The heat generated by the electrode may be discharged directly to the dielectric substrate, which may act as a heat sink and may even be connected to an additional heat sink.

[0021] In one implementation of the aspect, the piezoelectric layer is made of crystalline lithium niobate, lithium tantalate or aluminum nitride.

[0022] Scandium-doped Al x Sc 1-x N, however, if a larger resonant-antiresonant frequency gap is required, it is better to use lithium niobate with a strong "shear" piezoelectric module, such as e 15 or e 24 .

[0023] In an implementation of the aspect, the piezoelectric layer made of crystalline lithium niobate is a rotated ZY section, a 120° Y section, or a 128° Y section of a lithium niobate plate.

[0024] These piezoelectric materials, especially the cut surface of lithium niobate, can enhance the coupling of Lamb wave A1 mode and / or Lamb wave A3 mode with the horizontal electric field. This can roughly correspond to e 1,13 =e 1,5 Maximum value of the piezoelectric module. Alternative cuts may include ZX cut of lithium niobate, similar cuts of lithium tantalate, etc.

[0025] In one implementation of the aspect, the thickness of the piezoelectric layer is approximately half the wavelength of a shear bulk acoustic wave in the piezoelectric layer that propagates along the thickness direction and is displaced perpendicular to the electrode of the IDT structure; and / or the thickness d of the piezoelectric layer is approximately P In the range of 400 to 600 nm, and / or the thickness d of the piezoelectric layer P Determine the resonant frequency F R Roughly equal to Vs / (2*d P ), wherein Vs is the velocity of the shear bulk acoustic wave in the piezoelectric layer that propagates along the thickness direction and is displaced perpendicular to the electrode of the IDT structure.

[0026] For other frequencies, the thickness d P It can be in the range of 200 to 1500nm.

[0027] In an implementation of the aspect, the electrodes of the IDT structure are periodically arranged on the dielectric substrate with a spacing, wherein the spacing is a shear bulk acoustic wave 2*d in the piezoelectric layer. P The wavelength is in the range of 1 to 10 times.

[0028] In one implementation of the aspect, the electrodes of the IDT structure are periodically arranged on the dielectric substrate with a spacing, wherein the period of the first electrode or the second electrode of the IDT structure is determined by twice the spacing, which is smaller than the wavelength of any bulk acoustic wave propagating in the dielectric substrate in the sagittal plane at the operating frequency of the acoustic resonator device.

[0029] According to the above implementation, on the one hand, the distance between the first electrode and the second electrode is small enough, and on the other hand, the dielectric substrate (for example, made of diamond) has a sufficiently high acoustic wave velocity to suppress acoustic loss to the dielectric substrate.

[0030] In an implementation of the aspect, the electrode of the IDT structure is made of metal, for example, copper (Cu), aluminum (Al), molybdenum (Mo), gold (Au) or any alloy thereof.

[0031] The electrode may also include two or more different metal layers or materials to improve adhesion, and / or prevent acoustic migration of Al, Cu, etc.

[0032] In an implementation of the aspect, the electrode of the IDT structure is a conductive base for maintaining a distance between the piezoelectric layer and the surface of the dielectric substrate.

[0033] The conductive base helps make the acoustic resonator device more mechanically robust. In combination with the first and second bus bars, the conductive base can stably support the piezoelectric layer without affecting its ability to vibrate and resonate.

[0034] In one implementation of the aspect, the electrodes of the IDT structure include a first part and a second part having the same potential; the first part of the electrode is a conductive base arranged on the dielectric substrate, and the piezoelectric layer is arranged on the conductive base; the second part of the electrode is arranged on the side of the piezoelectric layer opposite to the first part, wherein the second part of each electrode clamps the piezoelectric layer and the first part of the electrode together.

[0035] The conductive base can be made of metal, such as the electrodes described above, and the substrate is a dielectric. Although this implementation is somewhat complicated to make, its advantage is that the horizontal electric field is more uniform and the coupling is stronger. In this way, the vertical electric field under / between the IDT electrodes will be reduced, and the generation of parasitic modes will also be reduced.

[0036] In an implementation of the first aspect, at least one front electrode and at least one rear electrode of the periodically arranged electrodes of the IDT structure are at a floating potential.

[0037] The floating potential electrodes further improve the performance of the acoustic resonator device, since acoustic energy losses through both ends of the structure are also avoided or reduced (thereby achieving a higher Q factor).

[0038] In summary, the present disclosure solves the above-mentioned shortcomings of traditional XBAR devices while retaining most of the advantages of traditional XBAR devices. In contrast to traditional XBAR devices, the acoustic resonator device of the present disclosure includes an IDT electrode disposed between a piezoelectric layer (e.g., a plate or a crystal film) and a dielectric substrate (e.g., a solid diamond or silicon carbide substrate with high thermal conductivity and / or high acoustic wave velocity). Specifically, in the case where the dielectric substrate has a high acoustic wave velocity, the relatively low losses caused by the radiation of body waves into the dielectric substrate can be further reduced or avoided. The electrode serves as both a stabilizing structure (e.g., a base) and an IDT structure to convert electrical signals into acoustic Lamb waves in the piezoelectric layer. It is noteworthy that the first bus bar and the second bus bar that can be disposed between the dielectric substrate and the piezoelectric layer also help support the piezoelectric layer, which can further enhance the mechanical stability of the acoustic resonator device.

[0039] Under the above conditions, for relatively small pitches, the piezoelectric layer is still a perfect acoustic waveguide despite the IDT structure being connected to the substrate, because the radiation into the substrate body is suppressed due to the destructive interference of the radiating body wave. The acoustic vibration can propagate only in the piezoelectric layer, as if it were suspended over a cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In conjunction with the accompanying drawings, the following description of specific embodiments will illustrate the above aspects and their implementation methods. In the drawings:

[0041] Figure 1 A cross-sectional view of an acoustic resonator device according to the present disclosure is shown. Only a small part of the periodic electrode system is schematically shown.

[0042] Figure 2 shows the absence of a piezoelectric layer Figure 1 A perspective top view of an acoustic resonator device.

[0043] Figure 3 shows a piezoelectric layer Figure 1 A perspective top view of an acoustic resonator device.

[0044] Figure 4 A cross-sectional view of an acoustic resonator device according to the present disclosure is shown.

[0045] Figure 5 A cross-sectional view of an acoustic resonator device according to the present disclosure is shown.

[0046] Figure 6 A simulation of admittance as a function of frequency for an exemplary acoustic resonator device according to the present disclosure is shown.

[0047] Figure 7 A simulation of admittance versus frequency for another exemplary acoustic resonator device according to the present disclosure is shown. DETAILED DESCRIPTION

[0048] Figure 1 , Figure 2 and Figure 3 An acoustic resonator device 100 according to the present disclosure is shown. Figure 2 and Figure 3 A perspective top view of the device 100 is shown, and Figure 1 The device 100 is shown along Figure 2 and Figure 3 A cross-sectional view along the dashed line AA is shown. Figure 2 The device 100 is not shown in its entirety, but for better illustration, the device 100 is shown without the piezoelectric layer 103 . Figure 3 Shown as Figure 2 The device 100 shown in FIG. 1 is similar to the device 100 shown in FIG. 1 , but with a piezoelectric layer 103 .

[0049] The acoustic resonator device 100 comprises a dielectric substrate 101. For example, the dielectric substrate 101 may be made of diamond, silicon carbide or boron nitride. Combinations of these materials may also be used. The dielectric substrate 101 may also be made of a weak piezoelectric material, such as quartz. The thermal conductivity of the dielectric substrate 101 may be higher than 100 W / m*K, and may even be higher than 200 W / m*K or 300 W / m*K.

[0050] The substrate 101 may be a thick substrate or may be composed of two or more substrate layers, wherein the top substrate layer may be a high acoustic velocity material as described above. The thickness of the dielectric substrate 101 may be 4 to 20 times the thickness of the piezoelectric layer. The dielectric substrate may be connected to any thick dielectric substrate located below the substrate 101, such as Figures 1 to 3 Silicon, quartz, fused silica, etc. not shown.

[0051] The acoustic resonator device 100 also includes an IDT structure 102, which includes a plurality of conductive first electrodes 102a (represented in gray) and a plurality of conductive second electrodes 102b (represented in white). The number of first electrodes 102a can be the same as the number of second electrodes 102b, and there can be a total of 4 to 300 electrodes 102a, electrodes 102b. The electrodes 102a and electrodes 102b can both be made of metal, wherein different metals can be used. The first electrode 102a can be made of the same or different material (e.g., metal) as the second electrode 102b. The first electrode 102a is connected to a first bus bar 105, and the plurality of conductive second electrodes 102b are connected to a second bus bar 104, wherein the bus bars 104 and 105 are connected only at Figure 2As can be seen in the figure, the busbars 104 and 105 can be arranged between the dielectric substrate 101 and the piezoelectric layer 103. The first electrode 102a and the second electrode 102b of the IDT structure 102 are periodically and alternately arranged one by one on the surface of the dielectric substrate 101. For example, the first electrode and the second electrode can be connected to the dielectric substrate 101 or to the piezoelectric layer 103 through a thermally conductive adhesive. The same applies to the busbars 104 and 105.

[0052] The device 100 further includes Figure 1 and Figure 3 But shown in Figure 2 The piezoelectric layer 103 is omitted, so that Figure 2 , the IDT structure 102 and the bus bars 104 and 105 can be more clearly seen because the IDT structure 102 and the bus bars 104 and 105 can be arranged on the dielectric substrate 101 below the piezoelectric layer 103. The piezoelectric layer 103 is arranged to maintain a certain distance from the dielectric substrate 101. That is, a gap is formed between the top surface of the dielectric substrate 101 and the bottom surface of the piezoelectric layer 103. It is worth noting that "top" can refer to one side of the acoustic resonator device 100 where the piezoelectric layer 103 is arranged, and "bottom" can refer to the other side of the acoustic resonator device 100 where the dielectric substrate 101 is arranged. In this gap, the electrodes 102a and 102b are arranged. The surface of the piezoelectric layer 103 is parallel to the surface of the dielectric substrate 101.

[0053] The piezoelectric layer 103 is disposed on the first electrode 102a and the second electrode 102b, respectively. Figure 1 In addition, the piezoelectric layer 103 is also disposed on the first bus bar 105 and the second bus bar 104, respectively. Figure 2 (without piezoelectric layer 103) and Figure 3 103). The electrodes 102a and 102b of the IDT structure 102 are used to convert an electrical signal into an acoustic Lamb wave that propagates in the piezoelectric layer 103. This can be achieved by applying a differential AC voltage at the resonant frequency of the piezoelectric layer 103 between the first bus bar 104 and the second bus bar 105 to which the first electrode 102a and the second electrode 102b are connected, or by applying an AC voltage at the resonant frequency to one of the first bus bar 104 and the second bus bar 105 and maintaining the other of the first bus bar 104 and the second bus bar 105 at a ground potential. In addition, the electrodes 102a, 102b and the bus bars 104, 105 provide mechanical stability for the piezoelectric layer 103. Due to the high thermal conductivity of the dielectric substrate 101 (see above values) and the electrodes 102a, 102b (for example, the electrodes can be made of metal), the power handling performance of the acoustic resonator device 100 is improved compared to conventional XBAR devices.

[0054] from Figures 1 to 3 As can be seen in FIG. 1 , the geometry of the acoustic resonator device 100 is different from that of a conventional XBAR device. Specifically, the piezoelectric layer 103 may be a crystalline piezoelectric film connected to the dielectric substrate 101 via electrodes 102a, electrodes 102a, and in addition to having the function of generating acoustic Lamb waves in the piezoelectric layer 103, the electrodes also serve as an anchor or base for supporting the piezoelectric layer 103.

[0055] The electrodes 102a, 102b may be periodically placed at the locations of the amplitude nodes of the acoustic Lamb waves in the piezoelectric layer 103, such as the Lamb wave A1 mode standing wave. The power handling performance in the acoustic resonator device 100 is significantly improved compared to conventional XBAR devices, because the heat generated primarily in the electrodes 102a, 102b may be immediately discharged to the dielectric substrate 101 through the bottom side of the electrodes, and the dielectric substrate may have a high thermal conductivity of more than 100 W / m*K. In addition, the parasitic resonances generated in the electrodes 102a, 102b are also significantly reduced. Specifically, parasitic propagation modes (e.g., S0 modes) are significantly reduced because these modes are dispersed over the electrodes 102a, 102b.

[0056] Figure 4 An acoustic resonator device 100 according to the present disclosure is shown, which is constructed on Figures 1 to 3 On the basis of the acoustic resonator device 100 . Figure 4 and Figures 1 to 3 The same elements are marked with the same reference symbols.

[0057] Figure 4 The acoustic resonator device 100 shown by way of example has Figure 1 Different numbers of electrodes 102a and 102b are shown in the figure to illustrate that the acoustic resonator device 100 is not limited to the number of electrodes 102a and 102b disposed on the dielectric substrate 101. The spacing 403 of the IDT structure 102 is Figure 4 The electrodes 102a and 102b of the IDT structure 102 are periodically arranged on the dielectric substrate 101 with a spacing 403. The spacing 403 is the distance between the center of the first electrode 102a and the center of the adjacent second electrode 102b (along the direction of the periodic electrode arrangement). The periods of the first electrode 102a and the second electrode 102b are respectively twice the spacing 403.

[0058] For example, the thickness d of the piezoelectric film P In comparison, the spacing 403 between the electrodes 102a and 102b may be large enough, for example, the spacing 403 may be large enough to shear the bulk acoustic wave 2*d in the piezoelectric layer 103. P The wavelength is in the range of 1 to 10 times, where dP is the thickness 401 of the piezoelectric layer 103, and the thickness 401 of the piezoelectric layer 103 may be in the range of 400 to 600 nm. That is, the thickness 401 of the piezoelectric layer 103 is approximately half the wavelength of a shear bulk acoustic wave propagating in the thickness direction of the piezoelectric layer 103 and displaced perpendicularly to the electrodes 102a and 102b of the IDT structure 102. The thickness 401 of the piezoelectric layer 103 may determine the resonant frequency F of the piezoelectric layer 103. R , which is roughly equal to Vs / (2*d P ), where Vs is the velocity of the shear bulk acoustic wave in the piezoelectric layer 103.

[0059] On the other hand, in order to avoid the radiation of body waves into the dielectric substrate 101, the spacing may be limited as described below. For example, the dielectric substrate 101 may have a relatively high acoustic wave velocity. This may prevent acoustic waves (e.g., Lamb wave A1 mode of acoustic Lamb waves in the piezoelectric layer 103) from radiating acoustic energy into the body of the dielectric substrate 101. In other words, body waves or vibrations excited by the electrodes 102a, 102b may bounce up and down in the piezoelectric layer 103, and the acoustic waves may not be radiated into the dielectric substrate 101, and in particular, may decay exponentially in the depth of the dielectric substrate 101. Under these conditions, even the piezoelectric layer 103 connected to the dielectric substrate 101 by the electrodes 102a, 102b may maintain an ideal waveguide without losing energy through the electrodes 102a, 102b. For example, the velocity V of a slow shear body wave propagating parallel to the surface in the dielectric substrate layer 102 in a direction perpendicular to the electrodes 102a, 102b is d It can be higher than the phase velocity Vph of the Lamb wave in the piezoelectric layer 103, that is, Vph = 2*p*F R It is worth noting that the resonant frequency F R may correspond to the operating frequency of the acoustic resonator device 100, and the spacing 403(p) may satisfy the condition p <V d / V s *d P .

[0060] also, Figure 4 The illustrated protection layer 402 , such as a dielectric layer or an oxide layer, may be disposed on top of the piezoelectric layer 103 , since it is not necessary to provide the electrodes 102 a , 102 b on the top surface of the piezoelectric layer 103 .

[0061] Figure 5 An acoustic resonator device 100 according to the present disclosure is shown. Figures 1 to 3 The acoustic resonator device 100 is further developed based on the above. Figure 5 and Figures 1 to 3 The same elements are marked with the same reference symbols.

[0062] Figure 5 The first electrode 102a of the IDT structure 102 is shown to include a first portion 501 and a second portion 502, and the second electrode 102b may include a first portion 503 and a second portion 504. The first portion 501 of the first electrode 102a has the same potential as the second portion 502 of the first electrode 102a, and the first portion 503 of the second electrode 102b has the same potential as the second portion 504 of the second electrode 102b. Both the portion 501 and the portion 502 are connected to the same bus bar 105 ( Figure 5 not shown).

[0063] The first parts 501 and 503 of the electrodes 102a and 102b can be conductive bases, respectively, which are arranged on the dielectric substrate 101 and protrude from the dielectric substrate 101. In this case, the piezoelectric layer 103 is arranged on the conductive base. The second parts 502 and 504 of the electrodes 102a and 102b are respectively arranged on the side of the piezoelectric layer 103 opposite to the first parts 501 and 503, and the second parts 502 and 504 of each electrode 102a and 102b sandwich the piezoelectric layer 103 and the first parts 501 and 503 of the electrodes 102a and 102b.

[0064] An exemplary acoustic resonator device 100 according to the present disclosure has been simulated using two-dimensional (2D) finite element method (FEM) software. The results of the broadband FEM simulation are shown in FIG. Figure 6 and Figure 7 Specifically, the results include Figure 6 and Figure 7 The variation of admittance with respect to frequency is shown.

[0065] Figure 6 An exemplary acoustic resonator device 100 is concerned with a dielectric substrate 101 made of silicon carbide and a piezoelectric layer 103 made of lithium niobate. The thickness 401 of the piezoelectric layer 103 is 400 nm. The electrodes 102a, 102b are aluminum electrodes with a height of 400 nm, where the height corresponds to the distance or gap between the dielectric substrate 101 and the piezoelectric layer 101. The spacing 403 of the electrodes 102a, 102b is 5 μm. In the simulation, the width of the electrodes 102a, 102b is taken to be 0.5 μm; in practice, it may be equal to or greater than about 0.5 μm.

[0066] Figure 6 The acoustic resonator device 100 shows a resonant frequency F of 4595 MHz RThe resonance Q factor is 460. The resonance admittance is 0.044 (for every two electrodes 102a, 102b). The anti-resonance frequency is 5167MHz. The distance between the resonance frequency and the anti-resonance frequency is 570MHz, i.e. 12.6%. The anti-resonance Q factor is 815. The anti-resonance impedance is about 40kOhm per pair of electrodes, and the aperture W=50μm.

[0067] Figure 6 The simulated acoustic resonator device 100 has a robust design, is capable of high power handling performance, and exhibits high coupling to the acoustic Lamb modes. Furthermore, the resistive losses in the device 100 are low. The device 100 is suitable for 5 GHz operation. Specifically, operation in the A3 Lamb mode with a 3 times frequency is also possible (at Figure 6 The device 100 also has an improved temperature coefficient of frequency (TCF).

[0068] Figure 7 The present invention relates to an exemplary acoustic resonator device 100 having a piezoelectric layer 103 made of a 128° Y-sectioned lithium niobate plate. The FEM simulated curves are for a plate thickness 401 of 400 nm and a spacing 403 of 3.5 μm between electrodes 102a, 102b. The dielectric substrate 101 is also made of silicon carbide. The admittance is normalized to 50 pairs of electrodes 102a, 102b and an aperture of 50 μm.

[0069] Figure 7 The acoustic resonator device 100 shows a resonant frequency F of 4695 MHz R The resonant Q factor is about 400. The resonant admittance is 0.027 (per two electrodes 102a, 102b), corresponding to about 0.4 Ohm for 50 pairs of Zres. The anti-resonant frequency is 5282 MHz. The distance between the resonant frequency and the anti-resonant frequency is 587 MHz, i.e. 11.8%. The anti-resonant Q factor is about 350. The anti-resonant impedance is about 5 kOhm.

[0070] Figure 7 The simulated acoustic resonator device 100 has Figure 6 Similar advantages are obtained for the acoustic resonator device 100 simulated in FIG. 1 . In both cases, SiC substrates are considered. In FEM simulations, diamond substrates or sufficiently thick diamond layers on dielectric substrate materials show better resonator parameters.

[0071] The invention has been described in conjunction with various embodiments as examples and in conjunction with implementations. However, from a study of the drawings, the invention and the independent claims, other variations will be understood and implemented by a person skilled in the art in implementing the claimed subject matter. In the claims and in the specification, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" does not exclude a plurality. A single element or other unit may fulfil the functions of several entities or items described in the claims. The enumeration of certain measures in mutually different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. An acoustic resonator device (100), characterized in that include: A dielectric substrate (101); An interdigital transducer (IDT) structure (102) comprises a plurality of conductive first electrodes (102a) connected to a first bus bar (105) and a plurality of conductive second electrodes (102b) connected to a second bus bar (104), wherein the first electrodes (102a) and the second electrodes (102b) are periodically and alternately arranged one by one on the surface of the dielectric substrate (101); A piezoelectric layer (103) is spaced apart from and arranged in parallel with the surface of the dielectric substrate (101); Wherein, the piezoelectric layer (103) is arranged on the first electrode and the second electrode (102a, 102b) of the IDT structure (102), and on the first bus bar and the second bus bar (104, 105); The IDT structure (102) is used to convert electrical signals into acoustic Lamb waves in the piezoelectric layer (103).

2. The acoustic resonator device (100) according to claim 1, characterized in that: The acoustic Lamb waves include a Lamb wave A1 mode and / or a Lamb wave A3 mode.

3. The acoustic resonator device (100) according to claim 1 or 2, characterized in that: The electrodes (102a, 102b) of the IDT structure (102) are connected to the piezoelectric layer (103) at the locations of the amplitude nodes of the acoustic Lamb waves.

4. The acoustic resonator device (100) according to any one of claims 1 to 3, characterized in that: The dielectric substrate (101) is made of diamond, silicon carbide or boron nitride.

5. The acoustic resonator (100) according to any one of claims 1 to 4, characterized in that: The thermal conductivity of the dielectric substrate (101) is higher than 100 W / m*K.

6. The acoustic resonator device (100) according to any one of claims 1 to 5, characterized in that: The piezoelectric layer (103) is made of crystalline lithium niobate, lithium tantalate or aluminum nitride.

7. The acoustic resonator device (100) according to claim 6, characterized in that: The piezoelectric layer (103) made of crystalline lithium niobate is a rotated ZY section, a 120° Y section or a 128° Y section of a lithium niobate plate.

8. The acoustic resonator device (100) according to any one of claims 1 to 7, characterized in that: The thickness (401) of the piezoelectric layer (103) is approximately half the wavelength of a shear bulk acoustic wave in the piezoelectric layer (103) that propagates along the thickness direction and is displaced perpendicularly to the electrodes (102a, 102b) of the IDT structure (102); and / or The thickness d of the piezoelectric layer (103) P (401) is in the range of 400 to 600 nm, and / or the thickness d of the piezoelectric layer (103) P (401) Determine the resonant frequency F R Roughly equal to Vs / (2*d P ), wherein Vs is the velocity of the shear bulk acoustic wave in the piezoelectric layer (103) propagating along the thickness direction and displacing the electrodes (102a, 102b) perpendicular to the IDT structure (102).

9. The acoustic resonator device (100) according to any one of claims 1 to 8, characterized in that: The electrodes (102a, 102b) of the IDT structure (102) are periodically arranged on the dielectric substrate (101) at a spacing (403), wherein the spacing (403) is a shear volume acoustic wave 2*d in the piezoelectric layer (103). P The wavelength is in the range of 1 to 10 times.

10. The acoustic resonator device (100) according to any one of claims 1 to 9, characterized in that: The electrodes (102a, 102b) of the IDT structure (102) are periodically arranged on the dielectric substrate (101) at a spacing (403), wherein the period of the first electrode (102a) or the second electrode (102b) of the IDT structure (102) is determined by twice the spacing (403) and is smaller than the wavelength of any bulk acoustic wave propagating in the dielectric substrate (101) on a sagittal plane at an operating frequency of the acoustic resonator device (100).

11. The acoustic resonator device (100) according to any one of claims 1 to 10, characterized in that: The electrodes (102a, 102b) of the IDT structure (102) are made of metal, such as copper (Cu), aluminum (Al), molybdenum (Mo), gold (Au) or any alloy thereof.

12. The acoustic resonator device (100) according to any one of claims 1 to 11, characterized in that: The electrodes (102a, 102b) of the IDT structure (102) are conductive bases used to maintain the distance between the piezoelectric layer (103) and the surface of the dielectric substrate (101).

13. The acoustic resonator device (100) according to any one of claims 1 to 12, characterized in that: The electrodes (102a, 102b) of the IDT structure (102) both include a first portion (501, 503) and a second portion (502, 504) having the same potential; The first part (501, 503) of the electrode (102a, 102b) is a conductive base arranged on the dielectric substrate (101), and the piezoelectric layer (103) is arranged on the conductive base; The second part (502, 504) of the electrode (102a, 102b) is arranged on the side of the piezoelectric layer (103) opposite to the first part (501, 503), wherein the second part (502, 504) of each electrode (102a, 102b) clamps the piezoelectric layer (103) and the first part (501, 503) of the electrode (102a, 102b) together.

14. The acoustic resonator device (100) according to any one of claims 1 to 13, characterized in that: At least one front electrode (102a, 102b) and at least one rear electrode (102a, 102b) of the periodically arranged electrodes (102a, 102b) of the IDT structure (102) are at a floating potential.

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