Piezoelectric trenches interleaved with electrodes of SAW resonators for improved performance

Abstract

A surface acoustic wave (SAW) resonator apparatus is provided. The SAW resonator device includes a first electrode positioned on an upper surface of a piezoelectric film; a second electrode positioned on the upper surface of the piezoelectric film; and a first piezoelectric trench (PZT) positioned between the first electrode and the second electrode, the first PZT including a recess in the piezoelectric film, the first PZT having a first trench depth. In some aspects, the piezoelectric trench may alternatively be positioned in a lower surface of the piezoelectric film. In some aspects, an angle of an edge of the piezoelectric trench and a position of the piezoelectric trench relative to the first electrode and the second electrode may be modified.

Description

[0001] Cross-referencing related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 503,017, filed May 18, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to acoustic resonators. Specifically, acoustic resonators may include piezoelectric trenches to deflect and reduce spurious content, thereby reducing interference and improving signal quality. Background Technology

[0004] An acoustic wave (AW) resonator is a device that uses piezoelectric materials to convert electrical energy into mechanical vibrations in order to filter and process electrical signals. AW resonators are commonly used in electronic communication devices. AW resonators are small, low-cost, and highly reliable electronic filters used in multiplexers, making them ideal for use in small electronic devices.

[0005] Due to several performance advantages, including low insertion loss, high selectivity, and small size, surface acoustic wave (SAW) resonators are widely used in communication applications. Aspects of AAW resonators include bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators. Designing AW filters with low insertion loss, sufficiently large passband width, good out-of-band rejection, and good isolation requires optimizing the technology and resonator geometry to achieve full coupling, a high quality factor, significant suppression of all spurious mode types, and reduction of loss mechanisms in all three dimensions. Following these principles generally allows for the construction of AW filters with sufficiently high signal quality by minimizing ripple and loss mechanisms in the filter response. Undesirable responses can be caused by the same filter or other filters within the passband of a multiplexer circuit. Therefore, cleaning up the resonator response over a wide frequency range is an important goal for improving existing AW resonator technology. Summary of the Invention

[0006] Embodiments of this disclosure include apparatus, systems, and methods for using piezoelectric trenches (PZTs) between electrodes of SAW resonators to improve performance. Aspects of this disclosure advantageously provide significantly reduced interference between filters in multiplexer circuits. Furthermore, aspects of this disclosure advantageously allow spurious contents of surface acoustic wave resonators to be shifted higher in the spectrum and the fundamental resonant frequency to be shifted lower in the spectrum, which can assist designers of various telecommunications circuit systems in avoiding interference between resonators or filters in their circuits, thereby improving performance.

[0007] In an exemplary aspect, a surface acoustic wave (SAW) resonator device is provided. The SAW resonator device includes a first electrode positioned on an upper surface of a piezoelectric film; a second electrode positioned on the upper surface of the piezoelectric film; and a first piezoelectric trench (PZT) positioned between the first and second electrodes, the first PZT including a recess in the piezoelectric film, the first PZT having a first trench depth.

[0008] On one hand, the first PZT is an upper PZT formed within the upper surface of the piezoelectric film. On another hand, the first PZT is a lower PZT formed within the lower surface of the piezoelectric film. On another hand, the first trench depth of the first PZT is in the range of 0% to 100% of the thickness of the piezoelectric film. On another hand, 100% trench depth corresponds to a fully etched PZT. On another hand, the first trench depth of the first PZT is in the range of 1 nm to 50 nm. On another hand, the first PZT is centrally aligned between the first electrode and the second electrode. On another hand, the piezoelectric film is positioned on one or more dielectric layers, which are positioned on a substrate. On another hand, the first PZT includes a lower width corresponding to the width of the first PZT at its bottom and an upper width corresponding to the width of the first PZT at its top. On another hand, the upper width is greater than the lower width. On another hand, the first PZT is symmetrical about an axis parallel to the first electrode. On one hand, the first PZT includes a first tilted region corresponding to a first angle and a second tilted region corresponding to a second angle. On another hand, the SAW resonator device further includes a second PZT and a third PZT, the second PZT being positioned within the piezoelectric film on the side of the first electrode opposite to the first PZT, such that a first piezoelectric platform with a first width is formed between the first PZT and the second PZT, and the third PZT being positioned within the piezoelectric film on the side of the second electrode opposite to the first PZT, such that a second piezoelectric platform with a second width is formed between the first PZT and the third PZT. On one hand, the width of the first electrode is equal to the first width of the first piezoelectric platform. On one hand, the width of the first electrode is less than the first width of the first piezoelectric platform. On one hand, the width of the first electrode is greater than the first width of the first piezoelectric platform. On one hand, the first electrode and the first platform are centrally aligned. On one hand, the piezoelectric film is positioned on a Bragg mirror. On one hand, the piezoelectric film is positioned on a piezoelectric substrate. On one hand, the piezoelectric film and the piezoelectric substrate are made of the same material type and the same material orientation. On another hand, the piezoelectric film is a freestanding piezoelectric film. On another hand, the SAW resonator device is part of a trapezoidal filter. On another hand, the SAW resonator device is part of a coupled resonator filter.

[0009] In some embodiments, the thickness of the piezoelectric layer is less than about five times the wavelength λ of the sound wave. In some embodiments, the thickness of the piezoelectric layer is about 5% to about 60% of the wavelength. In some embodiments, the piezoelectric element comprises / is lithium tantalate. In some embodiments, the piezoelectric element is lithium tantalate, wherein the orientation is generally between Y+0° and Y+60° and propagates along the x-axis of the crystal. In some embodiments, the piezoelectric element comprises / is lithium niobate. In some embodiments, the piezoelectric element is lithium niobate, wherein the orientation is generally between Y-20° and Y+60° and propagates along the x-axis of the crystal.

[0010] In an exemplary aspect, a surface acoustic wave (SAW) resonator device is provided. The SAW resonator device includes: a plurality of electrodes positioned on an upper surface of a piezoelectric film having a first thickness; and a plurality of piezoelectric grooves (PZTs) formed within the piezoelectric film between the plurality of electrodes, wherein the plurality of PZTs correspond to a region of the piezoelectric film having a second thickness, the second thickness being less than the first thickness.

[0011] On one hand, the plurality of electrodes are spaced apart by a first pitch, and the plurality of PZTs are spaced apart by a second pitch. On another hand, the first pitch is different from the second pitch. On yet another hand, the plurality of electrodes are spaced apart by a modulation pitch such that two or more electrodes of a first subset are spaced apart by the first pitch, and two or more interdigital transducers of a second subset are spaced apart by the second pitch.

[0012] In an exemplary aspect, a method for modifying a surface acoustic wave (SAW) resonator device is provided. The method includes: receiving the SAW resonator device; and applying an ion plasma to an upper surface of the SAW resonator device, such that the thickness of one or more interdigital transducers is reduced, and piezoelectric trenches are formed between the one or more interdigital transducers.

[0013] In an exemplary aspect, a method is provided. The method includes: receiving a surface acoustic wave (SAW) resonator device, the device comprising: a piezoelectric film; an interdigital transducer including a plurality of interlaced electrodes positioned on the piezoelectric film; and a sacrificial layer positioned on the plurality of interlaced electrodes; and applying an ion beam to an upper surface of the SAW resonator device such that the sacrificial layer is removed and piezoelectric trenches (PZTs) are formed between the plurality of interlaced electrodes.

[0014] In one aspect, the method further includes: patterning the plurality of interleaved electrodes located on the piezoelectric film; and patterning the sacrificial layer located on the plurality of interleaved electrodes. In another aspect, the interleaved electrodes and sacrificial material are patterned by sputtering, photolithography, and dry etching. In yet another aspect, the interleaved electrodes and sacrificial material are patterned by sputtering, material deposition, and lift-off.

[0015] In an exemplary aspect, a method is provided. The method includes: receiving a surface acoustic wave (SAW) resonator device, the device comprising: a piezoelectric film; and an interdigital transducer including a plurality of electrodes; and applying a wet etching process to an upper surface of the SAW resonator device such that the thickness of the plurality of electrodes is reduced and one or more piezoelectric trenches (PZTs) are formed between the plurality of electrodes.

[0016] In an exemplary aspect, a method is provided. The method includes: receiving a surface acoustic wave (SAW) resonator device, the device comprising: a piezoelectric film; and an interdigital transducer including a plurality of electrodes; and applying a wet etching process to a lower surface of the SAW resonator device such that the thickness of the plurality of electrodes is reduced and one or more piezoelectric trenches (PZTs) are formed between the plurality of electrodes.

[0017] On one hand, the piezoelectric film is bonded to a substrate handle using one or more intermediate layers. On another hand, the method further includes: positioning a first dielectric layer below the piezoelectric film; positioning a second dielectric layer on the top surface of the substrate wafer; and bonding the first dielectric layer and the second dielectric layer. On another hand, the method further includes planarizing the bottom surface of the piezoelectric film before bonding the first dielectric layer and the second dielectric layer. On one hand, the planarization of the bottom surface of the piezoelectric film is performed by wet etching. On another hand, the planarization of the bottom surface of the piezoelectric film is performed by dry etching. On another hand, the planarization of the bottom surface of the piezoelectric film is performed by removing material with ion plasma. On another hand, the planarization of the bottom surface of the piezoelectric film is performed by chemical mechanical polishing.

[0018] Further aspects, features, and advantages of this disclosure will become apparent from the following detailed description. Attached Figure Description

[0019] Illustrative embodiments of this disclosure will be described with reference to the accompanying drawings, in which:

[0020] Figure 1 This is a perspective view of a representative surface acoustic wave (SAW) device according to aspects of this disclosure.

[0021] Figure 2This is a cross-sectional side view of a SAW resonator.

[0022] Figure 3 This is a cross-sectional side view of a SAW resonator including piezoelectric grooves (PZT) according to aspects of this disclosure.

[0023] Figure 4 This is a comparison of two cross-sectional side views of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure.

[0024] Figure 5A According to an aspect of this disclosure, the absolute values ​​of the admittance of SAW resonators with and without piezoelectric grooves are graphically represented as fs / fp in the 2.2 GHz frequency range.

[0025] Figure 5B According to aspects of this disclosure, the conductance of SAW resonators with and without piezoelectric grooves is graphically represented as fs / fp in the 2.2 GHz frequency range.

[0026] Figure 5C According to an aspect of this disclosure, the absolute values ​​of the reflection coefficients of SAW resonators with and without piezoelectric grooves are graphically represented in the 2.2 GHz frequency range.

[0027] Figure 6A According to an aspect of this disclosure, the absolute values ​​of the admittance of SAW resonators with and without piezoelectric grooves are graphically represented as fs / fp in the 2.2 GHz frequency range.

[0028] Figure 6B According to an aspect of this disclosure, the conductance of a SAW resonator without piezoelectric grooves and a SAW resonator with piezoelectric grooves are graphically represented with fs / fp in the 2.2 GHz frequency range.

[0029] Figure 6C According to an aspect of this disclosure, the reflection coefficients of SAW resonators without piezoelectric grooves and SAW resonators with piezoelectric grooves are graphically represented with fs / fp in the 2.2 GHz frequency range.

[0030] Figure 7A According to an aspect of this disclosure, the absolute values ​​of the admittances of SAW resonators without piezoelectric grooves and SAW resonators with piezoelectric grooves are graphically represented with fs / fp in the 800 MHz frequency range.

[0031] Figure 7B According to aspects of this disclosure, the conductance of a SAW resonator without piezoelectric grooves and a SAW resonator with piezoelectric grooves are graphically represented with fs / fp in the 800 MHz frequency range.

[0032] Figure 7C According to an aspect of this disclosure, the absolute values ​​of the reflection coefficients of SAW resonators without and with piezoelectric grooves are graphically represented with fs / fp in the 800 MHz frequency range.

[0033] Figure 8 This is a schematic view of a trapezoidal filter according to aspects of this disclosure.

[0034] Figure 9A According to an aspect of this disclosure, the absolute values ​​of the admittance of a SAW resonator without piezoelectric grooves and a SAW resonator with piezoelectric grooves are graphically represented with respect to fs / fp in a frequency range of 2.2 GHz, which is shown as a frequency range much higher than fs / fp.

[0035] Figure 9B According to aspects of this disclosure, the conductance of a SAW resonator without piezoelectric grooves and a SAW resonator with piezoelectric grooves are graphically represented with fs / fp in a frequency range of 2.2 GHz, which is shown as a frequency range much higher than fs / fp.

[0036] Figure 9C According to an aspect of this disclosure, the absolute values ​​of the reflection coefficients of SAW resonators without piezoelectric grooves and SAW resonators with piezoelectric grooves are graphically represented with respect to fs / fp in a frequency range of 2.2 GHz, which is shown as a frequency range much higher than fs / fp.

[0037] Figure 10A This is a graphical representation of the transmission of a trapezoidal filter including a SAW resonator before and after the PAS trimming process, according to aspects of this disclosure.

[0038] Figure 10B According to aspects of this disclosure, the conductance of a SAW resonator without piezoelectric grooves and a SAW resonator with piezoelectric grooves used as a series resonator in a trapezoidal filter are graphically represented.

[0039] Figure 10C According to aspects of this disclosure, the conductance of a SAW resonator without piezoelectric grooves and a SAW resonator with piezoelectric grooves used as a parallel resonator for a trapezoidal filter are graphically represented.

[0040] Figure 10D According to an aspect of this disclosure, this is a graphical representation of the absolute values ​​of the admittance of a SAW resonator without piezoelectric grooves and a SAW resonator with piezoelectric grooves used as a series resonator in a trapezoidal filter.

[0041] Figure 10EAccording to an aspect of this disclosure, this is a graphical representation of the absolute values ​​of the admittance of a SAW resonator without piezoelectric grooves and a SAW resonator with piezoelectric grooves used as a parallel resonator in a trapezoidal filter.

[0042] Figure 11 This is a cross-sectional side view of a SAW resonator with piezoelectric grooves according to aspects of this disclosure.

[0043] Figure 12 This is a cross-sectional side view of a SAW resonator with offset piezoelectric grooves according to aspects of this disclosure.

[0044] Figure 13A This is a cross-sectional side view of an SAW resonator having an electrode pitch different from the piezoelectric groove pitch, according to aspects of this disclosure.

[0045] Figure 13B This is a cross-sectional side view of a SAW resonator with a varying piezoelectric trench geometry according to aspects of this disclosure.

[0046] Figure 14 This is a cross-sectional side view of a SAW resonator including a piezoelectric trench and a Bragg reflector according to aspects of this disclosure.

[0047] Figure 15 This is a cross-sectional side view of a SAW resonator including piezoelectric grooves formed in a bulk piezoelectric material, according to aspects of this disclosure.

[0048] Figure 16 This is a cross-sectional side view of a SAW resonator including piezoelectric grooves formed on a freestanding piezoelectric film, according to aspects of this disclosure.

[0049] Figure 17A It is a graphical representation of the absolute value of the admittance of a SAW resonator with piezoelectric trenches of different relative depths according to aspects of this disclosure.

[0050] Figure 17B This is a graphical representation of the conductance of a SAW resonator with piezoelectric trenches of different relative depths according to aspects of this disclosure.

[0051] Figure 17C This is a graphical representation of the quality factor of a SAW resonator with piezoelectric trenches of different relative depths according to aspects of this disclosure.

[0052] Figure 17D This is a graphical representation of the power dissipation of a SAW resonator with piezoelectric trenches of different relative depths according to aspects of this disclosure.

[0053] Figure 18AIt is a graphical representation of the absolute value of the admittance of a SAW resonator with a piezoelectric trench of different depths normalized relative to a common resonant frequency, according to aspects of this disclosure.

[0054] Figure 18B This is a graphical representation of the conductance of a SAW resonator with piezoelectric trenches of different depths normalized relative to a common resonant frequency, according to aspects of this disclosure.

[0055] Figure 18C This is a graphical representation of the quality factor of a SAW resonator with piezoelectric trenches of different depths normalized relative to a common resonant frequency, according to aspects of this disclosure.

[0056] Figure 18D This is a graphical representation of the power dissipation of a SAW resonator with piezoelectric trenches of different depths normalized relative to a common resonant frequency, according to aspects of this disclosure.

[0057] Figure 19A This is a graphical representation comparing the absolute values ​​of the admittances of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure.

[0058] Figure 19B This is a graphical representation comparing the conductance of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure.

[0059] Figure 19C This is a graphical representation comparing the quality factors of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure.

[0060] Figure 19D This is a graphical representation comparing the power dissipation of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure.

[0061] Figure 20A This is a graphical representation comparing the absolute values ​​of the admittances of SAW resonators with and without piezoelectric grooves relative to the resonant frequency, according to aspects of this disclosure.

[0062] Figure 20B This is a graphical representation of a comparison of the conductance of SAW resonators with and without piezoelectric grooves relative to the resonant frequency, according to aspects of this disclosure.

[0063] Figure 20C This is a graphical representation comparing the quality factors of SAW resonators with and without piezoelectric grooves relative to the resonant frequency, according to aspects of this disclosure.

[0064] Figure 20DThis is a graphical representation of a comparison of the power dissipation of SAW resonators with and without piezoelectric grooves relative to the resonant frequency, according to aspects of this disclosure.

[0065] Figure 21A It is a graphical representation comparing the absolute values ​​of the admittances of SAW resonators with and without piezoelectric grooves, as well as modulation pitch and duty cycle, according to aspects of this disclosure.

[0066] Figure 21B This is a graphical representation comparing the conductance of SAW resonators with and without piezoelectric grooves, as well as modulation pitch and duty cycle, according to aspects of this disclosure.

[0067] Figure 21C This is a graphical representation comparing the quality factors of SAW resonators with and without piezoelectric grooves, as well as modulation pitch and duty cycle, according to aspects of this disclosure.

[0068] Figure 21D This is a graphical representation comparing the power dissipation of SAW resonators with and without piezoelectric grooves, as well as modulation pitch and duty cycle, according to aspects of this disclosure.

[0069] Figure 22 It is a graphical representation of the performance comparison of SAW trapezoidal filters and series and parallel resonators made therefrom, based on aspects of this disclosure, with and without piezoelectric grooves.

[0070] Figure 23 This is a cross-sectional side view of a SAW resonator with a lower piezoelectric groove according to aspects of this disclosure.

[0071] Figure 24A It is a graphical representation of the absolute value of the admittance of a SAW resonator with a piezoelectric groove having different orientations according to aspects of this disclosure.

[0072] Figure 24B This is a graphical representation of the conductance of a SAW resonator with piezoelectric grooves having different orientations according to aspects of this disclosure.

[0073] Figure 24C This is a graphical representation of the quality factor of a SAW resonator with piezoelectric grooves having different orientations according to aspects of this disclosure.

[0074] Figure 24D This is a graphical representation of the power dissipation of SAW resonators with different orientations of piezoelectric grooves according to aspects of this disclosure.

[0075] Figure 25 This is a cross-sectional side view of a SAW resonator with a lower piezoelectric groove according to aspects of this disclosure.

[0076] Figure 26 This is a graphical representation of the relationship between the piezoelectric trench depth and the performance of the SAW resonator according to aspects of this disclosure.

[0077] Figure 27 This is a graphical representation of the relationship between the piezoelectric trench depth and the performance of the SAW resonator according to aspects of this disclosure.

[0078] Figure 28 This is a graphical representation of the relationship between the piezoelectric trench depth and the performance of the SAW resonator according to aspects of this disclosure.

[0079] Figure 29 This is a cross-sectional side view of a SAW resonator according to an aspect of this disclosure, wherein the sacrificial layer is positioned above the electrodes.

[0080] Figure 30 It is a graphical representation of a curve, showing the relationship between the orientation of the piezoelectric material (cut) according to aspects of this disclosure and the coupling of the dominant acoustic mode and pseudo-mode.

[0081] Figure 31 This is a graphical representation of the performance comparison of SAW devices having piezoelectric trenches on a piezoelectric layer with optimized crystal orientation and on a piezoelectric layer with unoptimized crystal orientation, according to aspects of this disclosure. Detailed Implementation

[0082] For the purpose of facilitating an understanding of the principles of this disclosure, embodiments will now be described with reference to the accompanying drawings and using specific language. Nevertheless, it should be understood that this is not intended to limit the scope of this disclosure. Any changes and further modifications to the described apparatus, systems, and methods, as well as any further application of the principles of this disclosure, are fully considered and included within this disclosure, as would normally occur to those skilled in the art to which this disclosure pertains. Specifically, upon careful consideration, features, components, and / or steps described with respect to one embodiment may be combined with features, components, and / or steps described with respect to other embodiments of this disclosure. However, for the sake of brevity, multiple repetitions of these combinations will not be described separately.

[0083] In an exemplary aspect, the AW device includes multiple electrodes. Piezoelectric trenches (PZTs) may be positioned between the electrodes. In some aspects, the PZTs may extend partially beneath the electrodes. The PZTs may have any suitable depth and any suitable width. The PZTs may be shaped with sloping edges referred to as shoulders. These shoulders may have any suitable slope or angle. The PZTs may be symmetrical or asymmetrical. The width of the PZT may be the same as, less than, or greater than, the distance between the electrodes. In some aspects, the PZTs may have any suitable cross-sectional shape, including circular, such as semi-circular, elliptical, or according to any other shape, profile, or pattern. The presence and varying geometry of the PZTs between the electrodes alter the fundamental frequency, reflectivity, and other resonator metrics of the SAW resonator. In particular, it can result in reduced velocity, reduced loss mechanisms, and increased reflectivity. Such an increase in reflectivity causes a larger stopband width (SBW) and a larger distance between the series resonance and the upper stopband edge (USBE). The reduced velocity also results in an increased velocity relative to the velocity of any bulk waves associated with and beneath the substrate. Furthermore, the frequency distance between the main resonance and the pseudomode increases significantly at higher frequencies, and the amplitude of the pseudomode decreases at higher frequencies. Since the stopband of the resonator defines the frequency range where losses due to leakage in the propagation direction are avoided, a large stopband width (SBW) can be beneficial. While other measures such as increasing thickness or optimizing the electrode material type may also affect reflectivity, PZT has the advantage of avoiding increased mechanical damping, which is inherent to the metal layer but can be very small for piezoelectric materials. Therefore, PZT can achieve higher SBW and higher quality factor while avoiding other typical drawbacks.

[0084] Adjustments to these parameters correspond to adjustments to the presence and amplitude of spurious content, allowing it to be moved out of the passband of other filters or completely eliminated. Aspects of this disclosure may also include pitch modulation. Both the electrode pitch and the PZT pitch can be modulated. SAW resonators with pitch modulation and PZT can drastically reduce spurious content below and above the passband, thereby significantly improving the performance of the SAW resonator. Any of the resonators described herein can be used in a variety of circuits. For example, a resonator with piezoelectric or dielectric trenches (described below) can be used as part of a filter, including a trapezoidal filter, a coupled resonator filter (CRF), or any other suitable filter.

[0085] Figure 1This is a perspective view of a representative surface acoustic wave (SAW) device according to aspects of this disclosure. While the principles of this disclosure are described in the context of SAW resonators, it should be understood that the presented techniques can be equally applied to any suitable type of acoustic wave (AW) resonator, including SAW resonators and BAW resonators. It can be applied in particular to any AW resonator employing interdigital transducer electrodes for various orientations of acoustic wave propagation and displacement relative to the arrangement of the electrodes. The SAW device 10 includes a substrate 12, a piezoelectric layer 14 on the substrate 12, an interdigital transducer (IDT) 16 including electrodes 22 on the surface of the piezoelectric layer 14 opposite to the substrate 12, a first reflector structure 18A on the surface of the piezoelectric layer 14 adjacent to the interdigital transducer 16, and a second reflector structure 18B on the surface of the piezoelectric layer 14 adjacent to the interdigital transducer 16 and opposite to the first reflector structure 18A. In some aspects, the interdigital transducer may also be referred to as an interdigitated transducer. In some respects, substrate 12 may be referred to as carrier substrate, and overall SAW device 10 may be referred to as guided SAW device.

[0086] The interdigital transducer 16 includes a first electrode 20A and a second electrode 20B, each of which includes a plurality of electrodes 22 interleaved with each other, as shown. The first electrode 20A and the second electrode 20B may also be referred to as comb electrodes. The lateral distance between adjacent electrodes 22 of the first electrode 20A and the second electrode 20B defines the pitch P between adjacent electrodes 22. The pitch P can at least partially define the resonant frequency of the corresponding electrode 22. In this respect, in embodiments where the pitch P between the electrodes 22 is uniform, all electrodes 22 can be configured to correspond to the same resonant frequency. This resonant frequency can be the resonant frequency of the SAW device 10. The resonant frequency can be the center frequency or dominant frequency of a mechanical wave generated by one or more electrodes 22 in the piezoelectric layer 14. The electrode width W of adjacent electrodes 22 and the pitch P can define the metallization ratio or duty cycle of the electrodes 22.

[0087] In operation, the AC input signal provided at the first electrode 20A is converted into a mechanical signal in the piezoelectric layer 14, thereby generating one or more acoustic waves. In the case of the SAW device 10, the resulting acoustic waves are predominantly surface acoustic waves. As discussed above, the magnitude and frequency of the converted acoustic waves in the piezoelectric layer 14 depend on the frequency of the AC input signal, based on the pitch P and metallization ratio of the interdigital transducer 16, the material properties of the piezoelectric layer 14, and other factors. This frequency dependence is typically described using changes in impedance and / or the phase shift between the first electrode 20A and the second electrode 20B relative to the frequency of the AC input signal. The AC potential between the first electrode 20A and the second electrode 20B induces an electric field in the piezoelectric material that generates the acoustic waves. The acoustic waves travel across the surface and are eventually transmitted back to the electrical signal between electrodes 20A and 20B. The first reflector structure 18A and the second reflector structure 18B reflect acoustic waves from the piezoelectric layer 14 back toward the interdigital transducer 16, thus confining the acoustic waves to a region surrounding the interdigital transducer 16. The substrate 12 can comprise various materials, including glass, sapphire, quartz, diamond, silicon (Si), or gallium arsenide (GaAs), with Si being a common choice. The piezoelectric layer 14 can be formed of any suitable piezoelectric material. In some embodiments described herein, the piezoelectric layer 14 is formed of lithium tantalate (LT) or lithium niobate (LiNbO3 or LN), but is not limited thereto. In some embodiments, the piezoelectric layer 14 is thick enough or rigid enough to serve as a piezoelectric substrate. Therefore, Figure 1 The substrate 12 may be omitted. Those skilled in the art will understand that the principles of this disclosure can be applied to other materials used for the substrate 12 and the piezoelectric layer 14. The interdigital transducer 16, the first reflector structure 18A, and the second reflector structure 18B may comprise one or more conductive materials, including silver (Au), gold (Ag), tungsten (W), molybdenum (Mo), nickel (Ni), ruthenium (Ru), iridium (Ir), chromium (Cr), platinum (Pt), titanium (Ti), aluminum (Al), copper (Cu), and alloys thereof, as well as alloys having other suitable materials, and may be made of a single layer or multiple layers. Although not shown to avoid obfuscation, additional dielectric layers or any other layers may be disposed above all or part of the exposed surfaces of the piezoelectric layer 14, the interdigital transducer 16, the first reflector structure 18A, and the second reflector structure 18B. Such additional passivation layers may form any surface topology, including but not limited to conformal coatings and planar surfaces. Such additional dielectric layers can be provided for purposes such as passivation, frequency correction, temperature compensation, and / or improved thermal conductivity. Suitable materials for such layers include silicon oxide, silicon nitride, titanium oxide, and aluminum oxide, and may also include dopants such as fluorine. Furthermore, in various embodiments, one or more layers may be disposed between the substrate 12 and the piezoelectric layer 14.

[0088] In some respects, SAW resonators, such as Figure 1 The SAW resonators shown and described may also be referred to as LRT-SAW, multilayer SAW, thin-film SAW, or any other suitable terminology.

[0089] Figure 2 This is a cross-sectional side view of the SAW resonator 200-1. The SAW resonator 200-1 includes various components, including a carrier substrate 245, a dielectric layer 240, a dielectric layer 235, a piezoelectric film 230, and two electrodes 222A and 222B.

[0090] The carrier substrate 245 forms the base of the SAW resonator 200-1 and provides structural support for the device. It can be made of a variety of materials, including glass, silicon, silicon carbide, quartz, diamond, sapphire, or any other suitable material. In some embodiments, the carrier substrate 245 can be selected based on its mechanical, thermal, or electrical properties to meet the needs of a specific application.

[0091] The dielectric layer 240 is positioned on top of the carrier substrate 245 and provides electrical insulation between the carrier substrate 245 and the remainder of the SAW resonator 200-1. In some aspects, the dielectric layer 240 may additionally provide a velocity contrast with the piezoelectric layer to help guide waves primarily concentrated in the piezoelectric layer. The dielectric layer 240 may also help avoid losses due to overlap with the carrier material and reduce TCF. The dielectric layer 240 may be made of a variety of materials, including silicon dioxide, silicon oxide, silicon nitride, or aluminum oxide, or any other material, depending on the specific application requirements.

[0092] In some respects, dielectric layer 240 may alternatively be a trap-rich layer (TRL). TRL may be, for example, silicon-based, such as polysilicon, or an implantation layer near the top surface of the carrier wafer itself.

[0093] Dielectric layer 235 is positioned on top of dielectric layer 240 and serves as a second electrical insulating layer. It can also be made of various materials, including any of those described with reference to layer 240. In some aspects, the resonator can comprise any suitable number of dielectric layers in any suitable arrangement.

[0094] A piezoelectric film 230 is positioned on top of the dielectric layer 235 and converts electrical energy into mechanical energy. The piezoelectric film 230 can be made of various materials, including lithium tantalate, lithium niobate, zinc oxide, aluminum nitride, scandium aluminum nitride, or any other material. In operation, the piezoelectric film 230 is excited by electrodes 222A and 222B to generate acoustic waves. A common choice for the piezoelectric layer is a thickness less than five times the wavelength λ of the acoustic wave. It is generally advantageous to have a thickness less than one wavelength and between about 5% and about 60% of the wavelength, but the invention disclosed herein is not limited to these examples. A common choice for the piezoelectric material is lithium tantalate, where the orientation is typically between about Y+0° and about Y+60° and propagates along the x-axis of the crystal. An orientation close to about 42° Y-XLT is a common choice, while an orientation close to about 30° YXLT can minimize the excitation of Rayleigh-type pseudo-acoustic modes in some cases. Another common choice for piezoelectric materials is lithium niobate, where the orientation is typically between approximately Y-20° and approximately Y+60° and propagates along the x-axis of the crystal. Large coupling coefficients can be obtained. In these piezoelectric layers, the device primarily excites waves with shear horizontal displacement, and the invention disclosed herein is not limited to optimizations concerning this wave type.

[0095] Electrodes 222A and 222B are positioned on top of piezoelectric film 230 and excite piezoelectric film 230. Transducers 222A and 222B are transducers within a series of alternating and / or interlaced fingers (see, for example...). Figure 1 Electrode 22). In operation, one of the transducers 222A or 222B can be connected to a positive potential while the other is connected to a negative potential, thereby generating acoustic waves in the piezoelectric film 230. Transducers 222A and 222B can be made of various materials, including any materials described herein, depending on the requirements of the specific application.

[0096] In some aspects, electrode 222 may include multiple layers. For example, electrode 222A may include layers 224A, 226A, and 228A. Similarly, electrode 222B may include layers 224B, 226B, and 228B. In some aspects, layers 228A and 228B may facilitate adhesion to the wafer to prevent atomic migration (into the substrate and along the surface) and to produce appropriate crystallinity of the overlying layers. Layers 226A and 226B may be made of electrical conductors (e.g., copper or aluminum). Layers 226A and 226B may ensure low resistance and low electrical losses in the IDT fingers. In some aspects, layers 224A and 224B may provide adhesion for additional metal layers (e.g., under-bump metal for wiring) and may help prevent oxidation and degradation of the underlying layers. In some respects, electrode 222 may include additional barrier layers or stacks of layers for similar purposes, including reducing sheet resistance, reducing mechanical damping, or increasing robustness to withstand environmental conditions such as moisture or excitation at high power.

[0097] Although Figure 2 The SAW resonator 200-1 shown is illustrated with only two electrodes, 222A and 222B; however, it should be understood that the device may include additional transducers. The number of electrodes can be determined by the specific application and the desired performance characteristics of the SAW resonator 200-1. In some respects, additional electrodes can be used to modify various characteristics of the SAW resonator 200-1. The material used to construct the additional transducers may be the same as or different from the material used for the initial electrodes.

[0098] Figure 3 A cross-sectional side view of a SAW resonator 200-2 including piezoelectric grooves (PZT) according to an aspect of this disclosure is shown. In some aspects, after a non-passivation dressing process (“PAS-free dressing”) has been performed, the SAW resonator 200-2 can be the same device as the SAW resonator 200-1. In some aspects, the SAW resonator 200-2 can be a different device from the SAW resonator 200-1. For example, it can be according to... Figure 3 The geometry shown is used to manufacture the SAW resonator 200-2.

[0099] In some aspects, the PAS-free finishing process involves removing material from the SAW resonator 200-1 using an ion beam. The ion beam can be a beam of charged particles, such as ions, accelerated and focused onto a region of the resonator using photolithography. The ion beam can scan across the surface of the resonator to selectively remove material.

[0100] In some respects, the PAS-free trimming process can increase the reflectivity of the SAW resonator and extend its stopband. In other respects, the PAS-free trimming process can further reduce the fundamental resonant frequency of the SAW resonator. In still other respects, the PAS-free trimming process may have a minor impact on other characteristics of the SAW resonator (such as the interaction between the resonator and other resonators in a filter, such as a trapezoidal filter) and on variations in the resonator's capacitance.

[0101] It should be noted that the shape of the resonator can be changed by altering the angle of the ion beam. Furthermore, the PAS-free trimming process can also be applied to reflectors 18A and 18B of the SAW resonator 200. Reflectors 18A and 18B can also be referred to as gratings.

[0102] According to a manufacturing process for SAW resonator 200-2, the resonator can initially be designed to have a fundamental resonant frequency higher than the desired fundamental resonant frequency. For example, SAW resonator 200-2 can initially be substantially similar to... Figure 2 The SAW resonator 200-1 is shown. In some aspects, a PAS-free trimming process can be performed on the SAW resonator 200-2. The geometry of the SAW resonator 200-2 can be the final cross-sectional shape of the SAW resonator 200-2. In this respect, the fundamental resonant frequency can be shifted downward to the desired fundamental resonant frequency through the PAS-free trimming process. By adjusting the characteristics and scanning parameters of the ion beam during the PAS-free trimming process, the fundamental resonant frequency can be precisely controlled to achieve the desired frequency.

[0103] like Figure 3 As shown, a piezoelectric groove (PZT) 370 can be formed without a PAS trimming process. The PZT can be a recessed region of the piezoelectric film between electrodes. Figure 3 In this example, PZT 370 can be located between electrodes 222A and 222B. PZT 370 can be formed within piezoelectric film 230 and can be a region with a reduced thickness compared to the region of piezoelectric film 230 located below electrodes 222A and 222B. In this respect, although the piezoelectric film 230 located below electrodes 222A and 222B can have a thickness of 260, the piezoelectric film 230 along PZT (such as PZT 370) can have a thickness of 360.

[0104] Similarly, a portion of the material of electrodes 222A and 222B can be removed during the PAS-free trimming process. For example, the thickness of electrodes 222A and 222B can be 350, where the thickness 350 is less than the thickness 250. However, in some aspects, the thickness of electrodes 222A and 222B can remain unchanged during the PAS-free trimming process. For example, electrodes 222A and 222B can be masked during the PAS-free trimming process, such that only a portion of the piezoelectric film 230 is removed between the electrodes, while the electrodes remain unaffected.

[0105] According to the alternative manufacturing process of SAW resonator 200-2, the piezoelectric film 230 can be modified to form PZT before the electrodes are positioned on it, such as... Figure 3 The PZT 370 is shown. For example, a hard mask can be positioned on the piezoelectric film 230. The PZT can then be formed within the piezoelectric film. After the PZT is formed, electrodes (such as...) are then... Figure 3 The electrodes 222A and 222B shown can be positioned on the piezoelectric film 230 between PZT.

[0106] In some respects, PAS-free trimming techniques can be used to adjust the fundamental resonant frequency of existing SAW resonators. This allows for greater flexibility in adjusting the frequency of SAW resonators without requiring complex redesigns or additional manufacturing steps. PAS-free trimming processes can also be used to adjust the resonator frequency across wafers to compensate for frequency variability caused by other process steps.

[0107] During the PAS-free trimming process, the amount of material removed from the SAW resonator can depend on many factors, including the exposure time to the ion beam, the power of the ion beam, and the gas composition used. The intensity of the ion beam refers to the density of charged particles in the beam and is typically measured in current density (e.g., microamps per square centimeter). Increasing the intensity of the ion beam allows for the removal of more material from the surface of the piezoelectric layer within a given amount of time. Similarly, the gas composition used can affect the efficiency and selectivity of the material removal process, as different gases react with the surface material in different ways. In general, for a given resonator design, precise parameters of the PAS-free trimming process can be optimized to obtain the desired results that have the desired impact on device performance.

[0108] As described in this disclosure, the amount of material removed from the SAW resonator during the PAS-free trimming process can vary depending on many factors. The piezoelectric layer can have any suitable thickness. In some aspects, the thickness of the piezoelectric layer 230 can be between 100 nanometers and 1000 nanometers. Any suitable amount of material can be removed during the PAS-free trimming process. In some aspects, more material is removed from the piezoelectric layer than from the electrodes. By controlling the amount of material removed during the PAS-free trimming process, the performance of the SAW resonator can be fine-tuned to meet specific design requirements.

[0109] The method disclosed herein for trimming SAW resonators can be applied to the entire SAW resonator or only a portion thereof. The method can be applied to any suitable resonator, such as a series or parallel resonator (sometimes called a shunt resonator) of a trapezoidal filter, or any other suitable resonator of any suitable filter.

[0110] In some respects, the method can be selectively applied to certain shunt resonators, such as those with the lowest frequencies, to achieve desired performance characteristics. Additionally, the method can be applied to resonators located near ports (such as antenna ports, receive ports, or transmit ports), which have the greatest impact on performance. This allows for more precise tuning of SAW resonators to optimize their performance.

[0111] To selectively apply the method to specific portions of the SAW resonator, the desired area can be covered with a mask to protect it from exposure to the ion beam. This makes the trimming process more flexible and precise. Alternatively, the method can be applied to any part of the SAW resonator.

[0112] In some respects, the selective application of trimming processes can be used to modify the characteristics of individual resonators in a filter. For example, in a multi-resonator filter, each resonator can be selectively trimmed to achieve a desired frequency response. This allows for the creation of custom filters with specific performance characteristics. The same applies to the coupled resonator filters (CRFs) that constitute such SAW devices and any subset of their associated geometries, electrodes, and electrode sections.

[0113] This is publicly available. Figure 4 A comparison between SAW resonator 200-1 and SAW resonator 200-2 is shown. Figure 4 As depicted, SAW resonator 200-1 is shown on the left, while SAW resonator 200-2 is shown on the right. It can be observed that electrodes 222A and 222B of SAW resonator 200-1 are thicker than those of SAW resonator 200-2. The thickness difference between the electrodes of the two resonators is due to… Figure 4The distance 450 is indicated in the figure. The reduction in electrode thickness in the SAW resonator 200-2 is due to the PAS-free trimming process performed on the resonator.

[0114] In addition, Figure 4 The piezoelectric film 230 between electrodes 222A and 222B of SAW resonator 200-1 is shown to be thicker than the piezoelectric film 230 between electrodes of SAW resonator 200-2. The thickness difference of the piezoelectric film between the two SAW resonators is due to... Figure 4 The distance 460 in the figure represents the distance. A distance of 460 is greater than a distance of 450, indicating that more piezoelectric film was removed compared to the electrode during the PAS-free finishing process.

[0115] Compared to SAW resonator 200-1, the reduced thickness of the electrodes and piezoelectric film in SAW resonator 200-2 may result in a frequency shift in SAW resonator 200-2 after a PAS-free trimming process. This may cause the resonant frequency of the SAW resonator to decrease or increase, depending on the resonator and the process type. However, for the purposes of this disclosure, the described PAS-free trimming process may result in a decrease in the resonant frequency of SAW resonator 200-1. Additionally, removing a small amount of piezoelectric film can increase the acoustic reflectivity of the SAW resonator, thereby increasing the stopband width of the resonator. Among other advantages, these can be achieved by using the PAS-free trimming process disclosed herein.

[0116] Figure 5A This is a graphical representation of the absolute values ​​of the admittance of the SAW resonator before and after the PAS trimming process, according to aspects of this disclosure. Figure 5A This includes graph 500A. Graph 500A may include an x-axis 510A corresponding to frequency and a y-axis 520A corresponding to admittance. As shown in graph 500A, dataset 530-1 represents the frequency response of the SAW resonator before trimming, while dataset 530-2 represents the frequency response of the same SAW resonator after trimming. Both datasets show the resonant frequency 531 and the anti-resonant frequency 532. The resonant frequency 531 represents the frequency at which the SAW resonator has maximum admittance, while the anti-resonant frequency 532 represents the frequency at which the SAW resonator has minimum admittance.

[0117] Compared to the resonant frequency 531-1 and the anti-resonant frequency 532-1, the resonant frequency 531-2 and the anti-resonant frequency 532-2 show a decreased shift along the spectrum. This shift in the spectrum is likely due to material removal from the SAW resonator during the PAS-free trimming process. Material removal results in a change in the thickness of the piezoelectric film between the electrodes, which in turn alters the frequency of the SAW resonator.

[0118] It is noteworthy that the SAW resonator responses before and after the PAS trimming process exhibit similar patterns. The resonant and anti-resonant frequencies of dataset 530-2 show a similar decrease in frequency shift compared to dataset 530-1. The frequency shift may depend on factors such as the type of ion beam used for trimming, the incident angle, and the trimming duration.

[0119] Variations in frequency response can be used to optimize SAW resonator design and improve its performance. Frequency offset can be used to adjust the resonant frequency of the SAW resonator to a desired value. This is particularly useful in applications such as filters, where a precise frequency response is required.

[0120] Figure 5B This is a graphical representation of the conductance of a SAW resonator before and after the PAS trimming process, according to an aspect of this disclosure. Figure 5B This includes graph 500B. Graph 500B may include an x-axis 510B corresponding to frequency and a y-axis 520B corresponding to conductance. As shown in graph 500B, dataset 540-1 represents the conductance of the SAW resonator before trimming, while dataset 540-2 represents the conductance of the same SAW resonator after trimming. Both datasets display the resonant frequency 541 and pseudo-content 542. The resonant frequency 541 in both datasets can be compared with a reference... Figure 5A The corresponding resonant frequency described is 531.

[0121] Similar to a reference Figure 5A The resonant frequency shift described is that resonant frequency 541-2 is shifted lower than resonant frequency 541-1. However, pseudo-content 542-2 can be shifted along the spectrum higher than pseudo-content 542-1. As shown, this decreasing shift at the fundamental resonant frequency and the increasing shift of the pseudo-content can result in a wider bandwidth between these two characteristics. This can advantageously allow the resonator to less interfere with the passband of filters (such as ladder filters or any other suitable circuits containing this resonator) and less interfere with the performance of filters at common ports.

[0122] Figure 5C This is a graphical representation of the absolute values ​​of the reflection coefficient of a SAW resonator before and after the PAS trimming process, according to aspects of this disclosure. Figure 5CThis includes graph 500C. Graph 500C may include an x-axis 510C corresponding to frequency and a y-axis 520C corresponding to the absolute value of the reflection coefficient. As shown in graph 500C, dataset 550-1 represents the absolute value of the reflection coefficient of the SAW resonator before trimming, while dataset 550-2 represents the absolute value of the reflection coefficient of the same SAW resonator after trimming. Dataset 550-1 displays pseudo-content 552-1, and dataset 550-2 displays pseudo-content 552-2. As shown, pseudo-content 552-2 is offset along the spectrum and is higher than pseudo-content 552-1. This higher offset of the pseudo-content may cause it to shift out of the filter's passband region.

[0123] Figures 6A-6C This data can be compared with that of SAW resonators before and after the PAS trimming process. (See above reference.) Figure 5A As shown and described, the absence of a PAS trimming process causes a downward shift in the fundamental resonant frequency. Consequently, in order for the SAW resonator to operate at the predetermined fundamental resonant frequency, the resonator must first be manufactured and designed such that the fundamental resonant frequency is higher than the desired frequency. Figures 6A-6C The graph shown corresponds to a comparison between a SAW resonator having a first resonant frequency without the PAS trimming process and a SAW resonator having the same resonant frequency without the PAS trimming process. In this respect, the SAW resonator undergoing the PAS trimming process may initially have a resonant frequency higher than the first resonant frequency, and then exhibit the first resonant frequency after the PAS trimming process.

[0124] in this regard, Figure 6A This is a graphical representation of the absolute values ​​of the admittance of a SAW resonator before and after the PAS trimming process, according to aspects of this disclosure. Figure 6A This includes graph 600A. Graph 600A may include an x-axis 610A corresponding to frequency and a y-axis 620A corresponding to admittance. As shown in graph 600A, dataset 630-1 represents the frequency response of the SAW resonator before trimming, while dataset 630-2 represents the frequency response of different SAW resonators after the no-PAS trimming process. As previously explained, the SAW resonator of dataset 630-2 can initially be designed to have a fundamental resonant frequency higher than the desired fundamental resonant frequency. The fundamental resonant frequency can be adjusted lower during the no-PAS trimming process so that it is aligned with the fundamental resonant frequency of the SAW resonator corresponding to dataset 630-1. Dataset 630-1 has a resonant frequency 631-1 and an anti-resonant frequency 632-1. Dataset 630-2 has a resonant frequency 631-2 and an anti-resonant frequency 632-2. Figure 6AAs shown, the resonant frequency 631-1 can be aligned with, be the same as, or be substantially the same as the resonant frequency 631-2. Similarly, the anti-resonant frequency 632-1 can be aligned with, be the same as, or be substantially the same as the resonant frequency 632-2.

[0125] Figure 6B This is a graphical representation of the conductance of a SAW resonator before and after the PAS trimming process, according to an aspect of this disclosure. Figure 6B This includes graph 600B. Graph 600B may include an x-axis 610B corresponding to frequency and a y-axis 620B corresponding to conductance. As shown in graph 600B, dataset 640-1 represents the conductance of the SAW resonator before trimming, while dataset 640-2 represents the conductance of different SAW resonators after the no-PAS trimming process. Both datasets show the resonant frequency 641 and pseudo-content 642. The resonant frequency 641 in both datasets can be compared with a reference... Figure 6A The corresponding resonant frequency described is 631.

[0126] In some respects, because a resonator corresponding to dataset 640-2 with a resonant frequency higher than the desired resonant frequency can be selected, and the desired resonant frequency is subsequently reduced during the PAS-free trimming process, the resonant frequency 641-2 can be aligned with, identical to, or substantially identical to the resonant frequency 641-1. However, dummy content 642-2 may be significantly higher in frequency than dummy content 642-1. For example, the frequency difference between dummy content 642-2 and 642-1 may be greater than the frequency difference between dummy content 542-2 and 542-1 (see [link to documentation]). Figure 5B The increased frequency difference between pseudo-content 642-2 and 642-1 can advantageously shift pseudo-content 642-2 out of the passband of other resonators or filters, thereby improving signal quality.

[0127] Figure 6C According to aspects of this disclosure, this is a graphical representation of the absolute values ​​of the reflection coefficients of a SAW resonator before and after the PAS trimming process. Figure 6CThis includes graph 600C. Graph 600C may include an x-axis 610C corresponding to frequency and a y-axis 620C corresponding to the absolute value of the reflection coefficient. As shown in graph 600C, dataset 650-1 represents the absolute value of the reflection coefficient of the SAW resonator before the PAS trimming process, while dataset 650-2 represents the absolute value of the reflection coefficient of different SAW resonators after the PAS trimming process. Dataset 650-1 displays pseudo-content 652-1, and dataset 650-2 displays pseudo-content 652-2. The frequency difference between pseudo-content 652-2 and 652-1 may be greater than the frequency difference between pseudo-content 552-2 and 552-1 (see [link to relevant documentation]). Figure 5C This increased frequency difference between pseudo-content 652-2 and 652-1 can advantageously shift pseudo-content 652-2 out of the filter's passband, thereby improving signal quality.

[0128] Similar to Figures 6A-6C , Figures 7A-7C This data can be compared with data from SAW resonators before and after the PAS trimming process. (See reference...) Figures 6A-6C As described, a resonator that has undergone a PAS-free trimming process and has a resonant frequency higher than the desired resonant frequency can be selected first. This resonant frequency is then adjusted downwards to the desired frequency to match an unmodified SAW resonator with similar characteristics. However, as... Figures 7A-7C As shown, with Figures 7A-7C The corresponding operating frequency range of the SAW resonator can be basically lower than that of the SAW resonator. Figures 6A-6C The corresponding operating frequency range of the SAW resonator. In this respect, the results of the PAS-free trimming process can be applied to SAW resonators with various frequency ranges, including low-frequency, mid-frequency, high-frequency, or any suitable type of SAW resonator.

[0129] Figure 7A According to aspects of this disclosure, this is a graphical representation of the absolute values ​​of the admittance of a SAW resonator before and after the PAS trimming process. Figure 7A This includes graph 700A. Graph 700A may include an x-axis 710A corresponding to frequency and a y-axis 720A corresponding to admittance. As shown in graph 700A, dataset 730-1 represents the frequency response of the SAW resonator before trimming, while dataset 730-2 represents the frequency response of different SAW resonators after the no-PAS trimming process. Dataset 730-1 has a resonant frequency 731-1 and an anti-resonant frequency 732-1. Dataset 730-2 has a resonant frequency 731-2 and an anti-resonant frequency 732-2. Figure 7AAs shown, the resonant frequency 731-1 can be aligned with, be the same as, or be substantially the same as the resonant frequency 731-2. Similarly, the anti-resonant frequency 732-1 can be aligned with, be the same as, or be substantially the same as the resonant frequency 732-2.

[0130] Figure 7B This is a graphical representation of the conductance of a SAW resonator before and after the PAS trimming process, according to an aspect of this disclosure. Figure 7B This includes graph 700B. Graph 700B may include an x-axis 710B corresponding to frequency and a y-axis 720B corresponding to conductance. As shown in graph 700B, dataset 740-1 represents the conductance of the SAW resonator before trimming, while dataset 740-2 represents the conductance of different SAW resonators after the no-PAS trimming process. Both datasets display the resonant frequency 741 and pseudo-content 742. The resonant frequency 741 in both datasets can be compared with a reference... Figure 7A The corresponding resonant frequency described is 731.

[0131] In some respects, because a resonator corresponding to dataset 740-2 with a resonant frequency higher than the desired resonant frequency can be selected, and the desired resonant frequency is subsequently reduced during the PAS-free trimming process, the resonant frequency 741-2 can be aligned with, be the same as, or substantially the same as the resonant frequency 741-1. However, the pseudo-content 742-2 may be significantly higher in frequency than the pseudo-content 742-1.

[0132] Figure 7C According to aspects of this disclosure, this is a graphical representation of the absolute values ​​of the reflection coefficients of a SAW resonator before and after the PAS trimming process. Figure 7C This includes graph 700C. Graph 700C may include an x-axis 710C corresponding to frequency and a y-axis 720C corresponding to the absolute value of the reflection coefficient. As shown in graph 700C, dataset 750-1 represents the absolute value of the reflection coefficient of the SAW resonator before the PAS trimming process, while dataset 750-2 represents the absolute value of the reflection coefficient of different SAW resonators after the PAS trimming process. Dataset 750-1 displays pseudo-content 752-1, and dataset 750-2 displays pseudo-content 752-2. The increased frequency difference between pseudo-content 752-2 and 752-1 can advantageously extend the passband of the resonator or the resonator's filter, and / or can offset pseudo-content 752-2 out of the passband-related frequency range of other resonators or filters, thereby improving signal quality.

[0133] Figure 8 This is a schematic view of a trapezoidal filter 800 according to aspects of this disclosure. Figure 8A trapezoidal filter 800 is depicted, which is a commonly used filter in communication systems. In one embodiment, the trapezoidal filter 800 includes five series resonators connected in series between a first port 810 and a second port 820. In addition to the series resonators, the trapezoidal filter 800 includes a parallel resonator connected between each series resonator to ground 850. Other components such as inductors or capacitors may be included in the topology, at the ports, in series or parallel with any resonator, or at ground; however, for simplicity, Figure 8 Not shown in the diagram. Series resonators may include series resonators 830, 832, 834, 836, and 838. Each series resonator may be a surface acoustic wave (SAW) resonator, a bulk acoustic wave (BAW) resonator, or any other type of resonator suitable for the filter.

[0134] Parallel resonators may include parallel resonators 842, 844, 846, and 848. Each parallel resonator may be any type of resonator listed in the reference series resonators.

[0135] The trapezoidal filter 800 can be designed to have a specific frequency response, such as a bandpass filter, notch filter, low-pass filter, or high-pass filter. The resonant frequencies of the series and parallel resonators can be adjusted to achieve the desired frequency response. In some aspects, the resonant frequencies of any series and / or parallel resonators can be adjusted using the PAS-free trimming process described in this disclosure. In some aspects, by applying the PAS-free trimming process, the pseudo-frequency of the trapezoidal filter 800 and / or individual resonators of the trapezoidal filter 800 can be changed without interfering with the performance of other resonators or filters.

[0136] In operation, the trapezoidal filter 800 receives a signal at the first port 810 and transmits the filtered signal to the second port 820. The filtered signal can be further filtered to remove unwanted frequencies or select specific frequencies of interest. The trapezoidal filter 800 can be used in various applications such as cellular communication systems, wireless local area networks (WLANs), GPS, or other communication systems.

[0137] It should be noted that a PAS-free trimming process can be performed on any suitable SAW resonator of the trapezoidal filter 800. For example, a PAS-free trimming process can be performed only on the series resonator 830. A PAS-free trimming process can be performed only on the series resonator 838. A PAS-free trimming process can be performed only on the parallel resonator 842. A PAS-free trimming process can be performed only on the parallel resonator 848. Depending on any pattern or design, a PAS-free trimming process can be performed on any other SAW resonator, SAW resonator group, or SAW resonator subgroup.

[0138] In some aspects, this disclosure may include coupled resonator filters (CRFs). Coupled resonator filters (CRFs) are commonly used in SAW filters and specifically in receiver (Rx) filters because they can be very small in size and can provide very good out-of-band rejection. In some aspects, the operation of a CRF can be based on the interaction of coupled acoustic modes of different IDT segments placed side by side within a common reflector. The primary parameter of this acoustic interaction is the reflection coefficient of the underlying unit cell (the IDT fingers with finite width on a piezoelectric material). The concept of PZT allows the reflection coefficient to be tunable by introducing a new degree of freedom. In this respect, the reflection coefficients of different IDT segments or individual IDT fingers can be varied to better optimize the IDT finger-based CRF structure and similar geometries.

[0139] Figure 9A According to aspects of this disclosure, this is a graphical representation of the absolute values ​​of the admittance of a SAW resonator before and after the PAS trimming process. Figure 9A This includes graph 900A. Graph 900A may include an x-axis 910A corresponding to frequency and a y-axis 920A corresponding to admittance. As shown in graph 900A, dataset 930-1 represents the frequency response of the SAW resonator before trimming, while dataset 930-2 represents the frequency response of different SAW resonators after the non-PAS trimming process. Dataset 930-1 includes multiple higher-order modes. Specifically, dataset 930-1 includes modes 931-1, 932-1, and 933-1. These higher-order modes may be caused by the plate mode or longitudinal displacement mode of the corresponding SAW resonator, or any other suitable type of mode. Similarly, dataset 930-2 includes multiple higher-order modes. Specifically, dataset 930-2 includes modes 931-2, 932-2, and 933-2. As shown in the figure, higher-order modes 931-2, 932-2, and 933-2 can be shifted along the spectrum above modes 931-1, 932-1, and 933-1. This is likely a result of the PAS-free trimming feature described in this paper. In this respect, after the PAS-free trimming feature, the higher-order modes of the SAW resonator can be shifted so as not to interfere with the other resonators of one or more filters in the circuit.

[0140] Figure 9B This is a graphical representation of the conductance of a SAW resonator before and after the PAS trimming process, according to an aspect of this disclosure. Figure 9BThis includes graph 900B. Graph 900B may include an x-axis 910B corresponding to frequency and a y-axis 920B corresponding to conductance. As shown in graph 900B, dataset 940-1 represents the frequency response of higher-order modes of a SAW resonator before the PAS trimming process, while dataset 940-2 represents the frequency response of higher-order modes of different SAW resonators after the PAS trimming process. Dataset 940-1 includes multiple higher-order modes. Specifically, dataset 940-1 includes modes 941-1, 942-1, and 943-1. These higher-order modes may be caused by the plate mode or longitudinal displacement mode of the corresponding SAW resonator, or any other suitable type of mode. Similarly, dataset 940-2 includes multiple higher-order modes. Specifically, dataset 940-2 includes modes 941-2, 942-2, and 943-2. As shown in the figure, higher-order modes 941-2, 942-2, and 943-2 can be shifted along the spectrum above modes 941-1, 942-1, and 943-1. This is likely a result of the PAS-free trimming feature described in this paper. In this respect, after the PAS-free trimming feature, the higher-order modes of the SAW resonator can be shifted so as not to interfere with the other resonators of one or more filters in the circuit.

[0141] Figure 9C According to aspects of this disclosure, this is a graphical representation of the absolute values ​​of the reflection coefficients of a SAW resonator before and after the PAS trimming process. Figure 9C This includes graph 900C. Graph 900C may include an x-axis 910C corresponding to frequency and a y-axis 920C corresponding to the absolute value of the reflection coefficient. As shown in graph 900C, dataset 950-1 represents the frequency response of higher-order modes of the SAW resonator before the PAS trimming process, while dataset 950-2 represents the frequency response of higher-order modes of different SAW resonators after the PAS trimming process. Dataset 950-1 includes multiple higher-order modes. Specifically, dataset 950-1 includes modes 951-1, 952-1, and 953-1. These higher-order modes may be caused by the plate mode or longitudinal displacement mode of the corresponding SAW resonator, or any other suitable type of mode. Similarly, dataset 950-2 includes multiple higher-order modes. Specifically, dataset 950-2 includes modes 951-2, 952-2, and 953-2. As shown in the figure, higher-order modes 951-2, 952-2, and 953-2 can be shifted along the spectrum above modes 951-1, 952-1, and 953-1. This is likely a result of the PAS-free trimming feature described in this paper. In this respect, after the PAS-free trimming feature, the higher-order modes of the SAW resonator can be shifted so as not to interfere with the other resonators of one or more filters in the circuit.

[0142] Figure 10A This is a graphical representation of the frequency response of a filter including a SAW resonator before and after a PAS trimming process, according to aspects of this disclosure. Figure 10A This includes graph 1000A. Graph 1000A may include an x-axis 1010A corresponding to frequency and a y-axis 1020A corresponding to the transmission of the filter between ports 1 and 2. In some aspects, graph 1000A may show a trapezoidal filter (such as...). Figure 8 The frequency response of a trapezoidal filter (800). As shown in the figure, graph 1000A includes datasets 1030-1 and 1030-2. In some aspects, dataset 1030-1 can be used with a trapezoidal filter (such as... Figure 8 The frequency response of the trapezoidal filter 800 corresponds to the frequency response of the trapezoidal filter that has not undergone the PAS-free trimming process. Dataset 1030-2 can be associated with the trapezoidal filter (e.g., after the PAS-free trimming process). Figure 8 The frequency response corresponds to that of the trapezoidal filter (800). As shown in the figure, as a result of the no-PAS trimming process, the passband can eliminate ripple or notch caused by the spurious response of the underlying parallel resonator. This is in Figure 10A As shown in the figure, the notch at the rightmost position 1031-1 falls within the passband, while this is not the case for dataset 1030-2.

[0143] Figure 10B This is a graphical representation of the conductance of a SAW resonator before and after the PAS trimming process, according to aspects of this disclosure. In some aspects, Figure 10B It can be compared to a series resonator (SR). Figure 10B This includes graph 1000B. Graph 1000B may include an x-axis 1010B corresponding to frequency and a y-axis 1020B corresponding to conductance. As shown in graph 1000B, dataset 1040-1 represents the conductance of the SAW resonator before trimming, while dataset 1040-2 represents the conductance of different SAW resonators after the no-PAS trimming process. Both datasets show the resonant frequency 1041. Resonant frequency 1041-2 may be aligned with, be the same as, or substantially the same as resonant frequency 1041-1.

[0144] Figure 10C This is a graphical representation of the conductance of a SAW resonator before and after the PAS trimming process, according to aspects of this disclosure. In some aspects, Figure 10C It can be compared to a parallel resonator (PR). Figure 10CThis includes graph 1000C. Graph 1000C may include an x-axis 1010C corresponding to frequency and a y-axis 1020C corresponding to conductance. As shown in graph 1000C, dataset 1050-1 represents the conductance of the SAW resonator before trimming, while dataset 1050-2 represents the conductance of different SAW resonators after the no-PAS trimming process. Both datasets show the resonant frequency 1051 and pseudo-content 1052. As previously referenced... Figure 6B and / or Figure 7B As described, due to the absence of a PAS trimming process, pseudo content 1052-2 can have a higher spectral offset than pseudo content 1052-1.

[0145] Figure 10D According to aspects of this disclosure, this is a graphical representation of the absolute values ​​of the admittance of a SAW resonator before and after the PAS trimming process. Figure 10D This includes graph 1000D. Graph 1000D may include an x-axis 1010D corresponding to frequency and a y-axis 1020D corresponding to admittance. As shown in graph 1000D, dataset 1060-1 represents the frequency response of the SAW resonator before trimming, while dataset 1060-2 represents the frequency response of different SAW resonators after the no-PAS trimming process. Dataset 1060-1 has a resonant frequency 1061-1 and an anti-resonant frequency 1062-1. Dataset 1060-2 has a resonant frequency 1061-2 and an anti-resonant frequency 1062-2. Figure 10D As shown, the resonant frequency 1061-1 can be aligned with, be the same as, or be substantially the same as the resonant frequency 1061-2. Similarly, the anti-resonant frequency 1062-1 can be aligned with, be the same as, or be substantially the same as the resonant frequency 1062-2.

[0146] Figure 10E According to aspects of this disclosure, this is a graphical representation of the absolute values ​​of the admittance of a SAW resonator before and after the PAS trimming process. Figure 10E This includes graph 1000E. Graph 1000E may include an x-axis 1010E corresponding to frequency and a y-axis 1020E corresponding to admittance. As shown in graph 1000E, dataset 1070-1 represents the frequency response of the SAW resonator before trimming, while dataset 1070-2 represents the frequency response of different SAW resonators after the no-PAS trimming process. Dataset 1070-1 has a resonant frequency 1071-1 and an anti-resonant frequency 1072-1. Dataset 1070-2 has a resonant frequency 1071-2 and an anti-resonant frequency 1072-2. Figure 10EAs shown, the resonant frequency 1071-1 can be aligned with, be the same as, or be substantially the same as the resonant frequency 1071-2. Similarly, the anti-resonant frequency 1072-1 can be aligned with, be the same as, or be substantially the same as the resonant frequency 1072-2.

[0147] Figure 11 This is a cross-sectional side view of a SAW resonator 1100 having piezoelectric grooves 1170 according to aspects of this disclosure. Figure 11 As shown, PZT can be configured according to any suitable geometry.

[0148] The SAW resonator 1100 can be similar to the previously referenced... Figure 2 and Figure 3 The SAW resonators 200-1 and / or 200-2 are described. Specifically, the SAW resonator 1100 may include a piezoelectric film 1130. The piezoelectric film 1130 may be similar to the piezoelectric film 230 previously described. In some aspects, the piezoelectric film 1130 may be positioned on layers 235, 240, and 245, such as Figure 11 As shown. The SAW resonator 1100 may also include multiple electrodes 1122. The electrodes 1122 may be similar to Figure 2 and Figure 3 Electrodes 222A and 222B.

[0149] The SAW resonator 1100 includes PZT 1170. In Figure 11 In the illustrated example, PZT 1170 may include a tapered edge or shoulder. Specifically, PZT 1170 includes a lower PZT width 1174 and an upper PZT width 1176. In the illustrated example, the upper PZT width 1176 may be greater than the lower PZT width 1174. Therefore, a shoulder is formed on either side of PZT 1170. These shoulders may be sloping regions extending from the top surface of piezoelectric film 1130 to the lower surface of PZT 1170. In some aspects, the shoulders of PZT 1170 may be sloping at an angle 1178. In some aspects, the sloping shoulders may be symmetrical about the central axis of PZT 1170. In other aspects, PZT 1170 may be asymmetrical. For example, one side of PZT 1170 may be sloping more steeply than the other side, or vice versa. Any suitable geometry of PZT 1170 may be used.

[0150] like Figure 11As shown, the PZT 1170 can have a depth of 1172, while the total thickness of the piezoelectric film 1130 can be 1160. In some respects, the performance of the SAW resonator 1100 can depend at least in part on the relationship between the depth 1172 of the PZT 1170 and the thickness 1160 of the piezoelectric film 1160. In some respects, this relationship can be quantified as a percentage of the thickness 1160 to the depth 1172, or a ratio between the two.

[0151] For example Figure 11 As shown, electrode 1122 may have a thickness of 1150. The width of electrode 1122 may be 1132, and electrodes 1122 may be spaced apart according to a pitch of 1142. Although not shown to avoid confusion with the diagram, an additional layer is disposed on all or part of the piezoelectric surface within the PZT and / or on top of the electrodes. This may include a dielectric layer, which may be used for temperature compensation, passivation, frequency trimming, or other purposes.

[0152] Figure 12 This is a cross-sectional side view of a SAW resonator 1200 having an offset piezoelectric groove 1270 according to aspects of this disclosure. The SAW resonator 1200 may be similar to the SAW resonator 1100. Specifically, the SAW resonator 1200 may include a piezoelectric film 1230. The piezoelectric film 1230 may be similar to the piezoelectric film 230 previously described (…). Figure 2 ) and / or piezoelectric film 1130 ( Figure 11 In some respects, the piezoelectric film 1230 can be positioned on layers 235, 240, and 245, such as... Figure 12 As shown. The SAW resonator 1100 may also include multiple electrodes 1122. In some respects, the electrodes may be suspended above the edge of the platform.

[0153] The SAW resonator 1200 includes the PZT 1270. For example... Figure 12 As shown, the PZT 1270 can be offset between electrodes 1122. Specifically, center line 1260 is shown. Center line 1260 can show the center point between electrodes 1122. Additionally, center line 1250 is shown. Center line 1250 can show the center point of PZT 1270. Figure 12As shown, centerline 1260 is not aligned with centerline 1250. Specifically, centerline 1250 may be positioned to the right of centerline 1260. However, in other respects, centerline 1250 of PZT 1270 may be positioned to the left of centerline 1260. Similar to PZT 1170, PZT 1270 may include a tapered edge or shoulder, as shown. In some respects, the region of piezoelectric film 1230 located between PZTs may be referred to as a plateau. In the example shown, the left edge of electrode 1122 may be aligned with the left edge of the piezoelectric plateau it is positioned on, as indicated by line 1240. Figure 12 As shown, flange 1280 can be positioned to the right of electrode 1122. In some respects, where the width of the piezoelectric platform is greater than the width of electrode 1122, electrode 1122 can be positioned at any suitable location along the platform. For example, flanges, such as flange 1280, can be positioned to the left of electrode 1122. In some respects, flanges can be positioned on either side of electrode 1122. In some respects, the offset positioning of electrode 1122 relative to PZT 1270 of SAW resonator 1200 can adjust the phase between the emitted and reflected acoustic waves along the IDT.

[0154] The SAW resonator 1200 can be fabricated using any suitable method. For example, a PZT, such as PZT 1270, can be formed within the piezoelectric film 1230 before positioning the electrodes 1122 on the piezoelectric film 1230. The PZT can be formed, for example, by photolithographic etching using a hard mask. This can include transferring a patterned design onto a substrate, the patterned design comprising PZTs located along the piezoelectric film 1230 between planned positions of the electrodes 1122. In some aspects, the hard mask can be a thin layer of material resistant to etching processes. After the PZTs are formed, electrodes can be positioned between the PZTs along the piezoelectric film 1230.

[0155] Figure 13A This is a cross-sectional side view of an SAW resonator 1300a having an electrode pitch different from the piezoelectric groove pitch, according to aspects of this disclosure. As previously described, the electrodes can be positioned on the piezoelectric platform at any suitable location. In this respect, and as... Figure 13A As shown, the position of the electrode on the piezoelectric platform can vary on the same resonator.

[0156] SAW resonator 1300a may include various components. The SAW resonator may be similar to any SAW resonator described herein. Specifically, SAW resonator 1300a includes a carrier substrate 1345, a dielectric layer or trap-rich layer 1340, a dielectric layer 1335, a piezoelectric film 1330, and five electrodes 1326.

[0157] The carrier substrate 1345 forms the basis of the SAW resonator 1300a. A dielectric layer or trap-rich layer 1340 is positioned on top of the carrier substrate 1345. A dielectric layer 1335 is positioned on top of the dielectric layer or trap-rich layer 1340. A piezoelectric film 1330 is positioned on top of the dielectric layer 1335.

[0158] exist Figure 13A In the example shown, multiple PZTs are formed in the piezoelectric film 1330. Electrodes 1322 may be spaced apart from each other by electrode pitch 1322. PZTs 1370 may be spaced apart from each other by PZT pitch 1324, which is different from the electrode pitch 1322. For example, electrode 1326a may be positioned such that the left edge of electrode 1326a is aligned with the left edge of the piezoelectric platform to the left of PZT 1370a. Electrode 1326b is spaced apart from PZT 1370a by electrode pitch 1322. The right edge of PZT 1370a may be spaced apart from the adjacent PZT by PZT pitch 1324. Because the electrode pitch 1322 is larger than PZT 1324 in this example, the leftmost edge of electrode 1326b may not be aligned with the rightmost PZT 1370a, as shown. Since each of the electrodes 1326 and PZT 1370 shown is similarly spaced apart from each other by electrode pitch 1322 and PZT pitch 1324, each of the electrodes 1326c, 1326d and 1326e can be spaced apart to the right by a constant degree on their respective piezoelectric platforms.

[0159] Figure 13B This is a cross-sectional side view of a SAW resonator 1300b with a varying piezoelectric trench geometry according to aspects of this disclosure. Figure 13B As shown, the piezoelectric trench of the SAW resonator 1300b can have any suitable geometry.

[0160] In the example shown, the SAW resonator 1300b includes a plurality of electrodes 1326. The plurality of electrodes 1327 can be spaced apart according to pitch 1323, or the spacing between different electrode pairs can have different pitches, or they may not follow a periodicity relative to other electrode pairs. However, it should be noted that the electrodes 1327 can be spaced apart according to different pitches, as shown in the reference... Figure 13A As described. Electrodes 1327 can also be spaced apart according to the piezoelectric groove pitch 1325, and can be spaced apart according to different piezoelectric groove pitches, as shown in the reference. Figure 13A As described.

[0161] In the example shown, a piezoelectric trench 1371a is shown between electrodes 1327a and 1327b. The piezoelectric trench 1371a may have a depth of 1373a. Similarly, the sides of the piezoelectric trench 1371a may be inclined at an angle of 1375a.

[0162] A piezoelectric trench 1371b is shown between electrodes 1327b and 1327c. The piezoelectric trench 1371b may have a depth of 1373b. Similarly, the sides of the piezoelectric trench 1371a may be tilted at any suitable angle. For example, the left side of the piezoelectric trench 1371b may be tilted at an angle of 1375b. In some aspects, the right side of the piezoelectric trench 1371b may be tilted at a different angle. Additionally, in some aspects, the bottom surface of the piezoelectric trench 1371b (or any other piezoelectric trench) may not be parallel to the SAW resonator 1300b. For example, the bottom surface of the piezoelectric trench 1371b may be tilted at an angle of 1379.

[0163] A piezoelectric trench 1371c is shown between electrodes 1327c and 1327d. The piezoelectric trench 1371c may have a depth of 1373c. The sides of the piezoelectric trench 1371c may be inclined at an angle of 1375c.

[0164] A piezoelectric trench 1371d is shown between electrodes 1327d and 1327e. The piezoelectric trench 1371d may have a depth of 1373d. Similarly, the sides of the piezoelectric trench 1371d may be inclined at an angle. For example, the right side of the trench may be inclined at an angle 1377 greater than the left side of the trench.

[0165] In some respects, piezoelectric trenches may not be formed between the electrodes, such as the space 1381 between electrodes 1327e and 1327f. The benefits of such different geometries along the IDT of a surface acoustic wave device can include achieving greater reflectivity for the reflector grating, while the electrodes of the IDT utilize different trade-offs between capacitance per unit area and reflectivity. In this way, SAW devices with variable PZT geometries will have improved performance.

[0166] Figure 14 This is a cross-sectional side view of an AW resonator 1400 including a piezoelectric trench 1470 and a Bragg reflector according to aspects of this disclosure. As shown, the AW resonator 1400 may include a plurality of electrodes 1422 positioned on a piezoelectric film 1430. The piezoelectric film includes PZT 1470. Figure 14 In the example shown, electrode 1422 can be centered with the piezoelectric platform shown. For example, a central axis 1460 corresponding to electrode 1422 and the piezoelectric platform is shown. In the example shown, because the width of the piezoelectric platform is greater than the width of electrode 1422, two flanges of equal size can be on either side of electrode 1422. However, as with any suitable geometry, as with the electrodes and corresponding PZTs described herein, any suitable geometry can be used.

[0167] exist Figure 14In the illustrated example, piezoelectric film 1430 may be positioned on a Bragg reflector. In the illustrated example, the Bragg reflector may include layers 1432, 1434, 1436, 1438, 1440, and 1442. These layers may be alternating layers of high and low acoustic impedance. Such layers may include dielectric or metallic materials. For example, layer 1432 may be a high acoustic impedance dielectric layer. Layer 1434 may be a low acoustic impedance dielectric layer. Layer 1436 may be a high acoustic impedance dielectric layer. Layer 1438 may be a low acoustic impedance dielectric layer. Dielectric layer 1440 may be a high acoustic impedance dielectric layer. Dielectric layer 1442 may be a low acoustic impedance dielectric layer. In some examples, layer 1444 may be a substrate similar to any substrate described herein.

[0168] Figure 15 This is a cross-sectional side view of a SAW resonator 1500 including piezoelectric grooves 1570 formed in a bulk piezoelectric material according to aspects of this disclosure. As shown, the SAW resonator 1500 may include a plurality of electrodes 1522 positioned on a bulk piezoelectric material 1530. The piezoelectric material includes PZT 1570. Figure 15 In the example shown, electrode 1522 can be centered and aligned with the piezoelectric platform shown. Although not shown to avoid obscuring the diagram, additional layers may be disposed on all or part of the piezoelectric surface within the PZT and / or on top of the electrodes. This may include a dielectric layer, which can be used for temperature compensation, passivation, frequency correction, or other purposes.

[0169] Figure 16 This is a cross-sectional side view of an AW resonator 1600 according to aspects of this disclosure, including piezoelectric grooves 1670 formed on a freestanding piezoelectric film 1630. As shown, the AW resonator 1600 may include a plurality of electrodes 1622 positioned on the freestanding piezoelectric film 1630. The dielectric material includes PZT 1670. Figure 16 In the example shown, electrode 1622 can be centered and aligned with the piezoelectric platform shown. Although not shown to avoid obscuring the diagram, additional layers can be disposed on all or part of the piezoelectric surface within the PZT and / or on top of the electrodes. This can include a dielectric layer, which can be used for temperature compensation, passivation, frequency correction, or other purposes. Furthermore, additional layers and geometries can be added to the bottom surface of the piezoelectric film. This can include variations in the dielectric layer or bottom electrode and the bottom morphology of the piezoelectric film, including the formation of the PZT.

[0170] Figure 17A It is a graphical representation of the absolute value of the admittance of a SAW resonator with piezoelectric trenches of different relative depths according to aspects of this disclosure. Figure 17AThis includes graph 1700A. Graph 1700A includes datasets 1730-1, 1730-2, 1730-3, and 1730-4. In some aspects, dataset 1730-1 may be a dataset corresponding to the frequency response of a SAW resonator without PZT. Dataset 1730-2 may be a dataset corresponding to the frequency response of a SAW resonator with PZT having a first depth. In some aspects, the first depth may be in the range of 9% to 15%. In one aspect, the first depth may be 12%. As previously described, the depth of PZT can be defined as a percentage of the PZT depth relative to the dielectric film thickness. For example, if the PZT depth is 70 nm and the dielectric film thickness is 700 nm, the PZT depth can be defined as 10%. Similarly, a ratio can be used. In the example of 70 nm PZT within a 700 nm dielectric film, this depth can be defined as a ratio of 1:10. Dataset 1730-3 can be a dataset corresponding to the frequency response of a SAW resonator with a second depth of PZT. In some aspects, the second depth can be in the range of 15% to 21%. In one aspect, the second depth can be 18%. Dataset 1730-4 can be a dataset corresponding to the frequency response of a SAW resonator with a third depth of PZT. In some aspects, the third depth can be in the range of 21% to 27%. In one aspect, the first depth can be 24%. In this respect, 0% trench depth can correspond to the absence of PZT. 100% trench depth can correspond to fully etched PZT. Fully etched PZT can be a trench that extends completely through the film directly beneath the electrode. For example, PZT 1371a between electrodes 1327a and 1327b can be an example of fully etched PZT.

[0171] In some respects, dataset 1730-1 includes a resonant frequency 1731-1 and an anti-resonant frequency 1732-1. As shown in the figure, the resonant frequency 1731-1 can be a lower frequency than the anti-resonant frequency 1732-1.

[0172] Dataset 1730-2 includes resonant frequency 1731-2 and anti-resonant frequency 1732-2. Dataset 1730-2 shows how the PZT trench of the SAW resonator corresponding to Dataset 1730-2 is offset downwards from resonant frequency 1731-2 and anti-resonant frequency 1732-2.

[0173] Similarly, dataset 1730-3 includes resonant frequency 1731-3 and anti-resonant frequency 1732-3. Dataset 1730-3 shows how the PZT trench of the SAW resonator corresponding to dataset 1730-3 is offset downwards at resonant frequency 1731-3 and anti-resonant frequency 1732-2.

[0174] Dataset 1730-4 includes resonant frequency 1731-4 and anti-resonant frequency 1732-4. Dataset 1730-4 shows how the PZT trench of the SAW resonator corresponding to Dataset 1730-4 is offset downwards from resonant frequency 1731-4 and anti-resonant frequency 1732-4.

[0175] Figure 17B This is a graphical representation of the frequency response of a SAW resonator with piezoelectric trenches of different relative depths according to aspects of this disclosure. Figure 17B Includes graph 1700B. Graph 1700B includes datasets 1740-1, 1740-2, 1740-3, and 1740-4. In some respects, dataset 1740-1 can be used with a SAW resonator without PZT (such as with...). Figure 17A Dataset 1740-2 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 1730-1. Dataset 1740-3 can be a dataset corresponding to the SAW resonator of dataset 1730-3. Dataset 1740-4 can be a dataset corresponding to the SAW resonator of dataset 1730-4.

[0176] In some respects, dataset 1740-1 includes peaks 1741-1 and 1742-1. Dataset 1740-2 includes peaks 1741-2 and 1742-2. Dataset 1740-3 includes peaks 1741-3 and 1742-3. Dataset 1740-4 includes peaks 1741-4 and 1742-4.

[0177] like Figure 17B As shown, with increasing PZT depth, the peaks corresponding to the upper stopband edge (e.g., peaks 1742-1, 1742-2, 1742-3, and 1742-4) can shift and increase along the spectrum. As described in more detail below, this shift in the upper stopband edge can significantly improve the performance of SAW resonators and / or the signal quality of SAW resonator-based filters.

[0178] Figure 17C This is a graphical representation of the quality factor of a SAW resonator with piezoelectric trenches of different relative depths according to aspects of this disclosure. Figure 17C Includes curve 1700C. Curve 1700C includes datasets 1750-1, 1750-2, 1750-3, and 1750-4. In some respects, dataset 1750-1 can be used with SAW resonators without PZT (such as with...). Figure 17A Dataset 1730-1 and / or Figure 17BDataset 1750-2 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 1730-2 and / or 1740-2. Dataset 1750-3 can be a dataset corresponding to the SAW resonator of dataset 1730-3 and / or 1740-3. Dataset 1750-4 can be a dataset corresponding to the SAW resonator of dataset 1730-4 and / or 1740-4.

[0179] like Figure 17C As shown, the quality factor of the SAW resonator increases with the depth of the PZT trench. For example, the peak value of the quality factor shown in dataset 1750-1 is indicated by line 1751-1. The peak value of the quality factor shown in dataset 1750-2 is indicated by line 1751-2. As shown, the peak value indicated by line 1751-2 is larger than the peak value indicated by line 1751-1. The peak value of the quality factor shown in dataset 1750-3 is indicated by line 1751-3, and the peak value indicated by line 1751-3 is larger than the peak value indicated by line 1751-2. Finally, the peak value of the quality factor shown in dataset 1750-4 is indicated by line 1751-4, and the peak value indicated by line 1751-4 is larger than the peak value indicated by line 1751-3.

[0180] In some respects, an increase in the quality factor of a SAW resonator can correspond to a reduction in its losses. In other respects, this reduced loss may be a result of acoustic energy being localized further away from the metal electrodes. In this regard, the more the trench depth increases, the more the quality factor improves, until a limit is reached. The depth of the piezoelectric trench can be increased without affecting the electrode thickness by protecting the top side of the electrodes, for example, by using a sacrificial layer that can be removed in later manufacturing steps, thus allowing for any suitable trench depth.

[0181] Figure 17D This is a graphical representation of the dissipated power of a SAW resonator with piezoelectric trenches of different relative depths according to aspects of this disclosure. The dissipated power can also be referred to as the absorbed power. Figure 17DThis includes graph 1700D. Graph 1700D includes datasets 1760-1, 1760-2, 1760-3, and 1760-4. In some respects, dataset 1760-1 may be a dataset corresponding to the frequency response of a SAW resonator without PZT (such as the same SAW resonator corresponding to datasets 1730-1, 1740-1, and / or 1750-1). Dataset 1760-2 may be a dataset corresponding to the SAW resonators of datasets 1730-2, 1740-2, and / or 1750-2. Dataset 1760-3 may be a dataset corresponding to the SAW resonators of datasets 1730-3, 1740-3, and / or 1750-3. Dataset 1760-4 may be a dataset corresponding to the SAW resonators of datasets 1730-4, 1740-4, and / or 1750-5.

[0182] In some respects, dataset 1760-1 includes peaks 1761-1 and 1762-1. Dataset 1760-2 includes peaks 1761-2 and 1762-2. Dataset 1760-3 includes peaks 1761-3 and 1762-3. Dataset 1760-4 includes peaks 1761-4 and 1762-4.

[0183] like Figure 17D As shown, as the depth of PZT increases, the peaks corresponding to the upper stopband edge (e.g., peaks 1762-2, 1762-3, and 1762-4) can shift and increase along the spectrum.

[0184] Figure 18A This is a graphical representation of the absolute values ​​of the admittance of SAW resonators with piezoelectric trenches of different depths normalized relative to the resonant frequency, according to aspects of this disclosure. As previously described, including PZT in an SAW resonator can reduce the fundamental resonant frequency. To compensate for the shift in the fundamental resonant frequency, the SAW resonator can be selected such that, after a PAS trimming process, the final resonant frequency corresponds to the desired target resonant frequency. Alternatively, in other aspects, the SAW resonator can be designed to include PZT as explained and is designed to the desired resonant frequency. To demonstrate the effect of PZT positioned within an SAW resonator having the same fundamental frequency, Figures 18A-18D The data can be normalized with respect to the fundamental resonant frequency. For example, Figures 18A-18D The data can be compared with Figures 17A-17D The data corresponds to each other, but can be divided by the resonant frequency of each dataset.

[0185] in this regard, Figure 18AThis includes graph 1800A. Graph 1800A includes datasets 1830-1, 1830-2, 1830-3, and 1830-4. In some aspects, dataset 1830-1 may be a dataset corresponding to the frequency response of a SAW resonator without PZT. Dataset 1830-2 may be a dataset corresponding to the frequency response of a SAW resonator with a first depth of PZT. In some aspects, Figures 18A-18D The first depth of PZT can be compared with Figures 17A-17D The first depth of the PZT can be the same as or different from that of the PZT. Dataset 1830-3 can be a dataset corresponding to the frequency response of a SAW resonator with a second depth, which can be the same as that of the PZT. Figures 17A-17D The second depth of the PZT may be the same as or different from that of the PZT. Dataset 1830-4 may be a dataset corresponding to the frequency response of a SAW resonator with a third depth, which may be the same as that of the PZT. Figures 17A-17D The third depth of the PZT may be the same or different.

[0186] like Figure 18A As shown, each of datasets 1830-1, 1830-2, 1830-3, and 1830-4 includes a peak 1831 aligned around a normalized fundamental frequency. Each of datasets 1830-1, 1830-2, 1830-3, and 1830-4 also includes an anti-resonant frequency 1832. As shown, the anti-resonant frequencies 1832 can be misaligned, but can be similar. This may slightly reduce the effective coupling coefficient of the SAW resonator.

[0187] Figure 18A The study also shows how the overall amplitude of datasets 1830-1, 1830-2, 1830-3, and 1830-4 decreases with increasing PZT depth. This may indicate a decrease in the capacitance of the SAW resonator.

[0188] Figure 18B This is a graphical representation of the frequency response of a SAW resonator with piezoelectric trenches of different depths relative to the resonant frequency, according to aspects of this disclosure. Figure 18B Includes graph 1800B. Graph 1800B includes datasets 1840-1, 1840-2, 1840-3, and 1840-4. In some respects, dataset 1840-1 can be used with a SAW resonator without PZT (such as with...). Figure 18ADataset 1840-2 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 1830-1. Dataset 1840-3 can be a dataset corresponding to the SAW resonator of dataset 1830-3. Dataset 1840-4 can be a dataset corresponding to the SAW resonator of dataset 1830-4.

[0189] Similar to plot 1800A, the dataset in plot 1800B is normalized about the resonant frequency for comparison. As a result, the peak 1841 of each dataset in datasets 1840-1, 1840-2, 1840-3, and 1840-4 is aligned around the center normalized frequency.

[0190] In some respects, dataset 1840-1 includes peak 1842-1. Peak 1842-1 may correspond to the upper stopband edge of the resonator. Dataset 1840-2 includes peak 1842-2. Dataset 1840-3 includes peak 1842-3. Dataset 1840-4 includes peak 1842-4.

[0191] As previously referenced Figure 17B As described, with increasing PZT depth, the peak corresponding to the upper stopband edge can shift and increase along the spectrum. When the fundamental frequency is normalized, Figure 18B The curve 1800B more clearly illustrates the extent of this shift at the upper stopband edge. As shown, peak 1842-2, corresponding to the first PZT depth, is significantly higher in frequency than peak 1842-1. Furthermore, peak 1842-3 is higher in frequency than peak 1842-2, and peak 1842-4, corresponding to the maximum depth in the provided example, is still higher in frequency. This shift at the upper stopband edge can shift pseudo-content out of the frequency passband and the passbands of other filters, thereby significantly improving signal quality and the performance of the multiplexer circuitry.

[0192] It was also noted that each of the peaks 1842-2, 1842-3, and 1842-4, in addition to an increased frequency offset, also exhibited successively lower amplitudes. As a result, the degree of spurious content in other frequency bands that could interfere with other filters was also significantly reduced, thereby greatly improving signal quality.

[0193] Figure 18C This is a graphical representation of the quality factor of a SAW resonator with piezoelectric grooves of different depths normalized relative to the center fundamental frequency, according to aspects of this disclosure. Figure 18CIncludes curve 1800C. Curve 1800C includes datasets 1850-1, 1850-2, 1850-3, and 1850-4. In some respects, dataset 1850-1 can be used with SAW resonators without PZT (such as with...). Figure 18A Dataset 1830-1 and / or Figure 18B Dataset 1850-2 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 1830-2 and / or 1840-2. Dataset 1850-3 can be a dataset corresponding to the SAW resonator of dataset 1830-3 and / or 1840-3. Dataset 1850-4 can be a dataset corresponding to the SAW resonator of dataset 1830-4 and / or 1840-4. For example... Figure 18C As shown, the quality factor of the SAW resonator increases with the depth of the PZT. Specifically, the quality factor of the SAW resonator can increase with the depth of the PZT at the fundamental resonant frequency (Qs), the anti-resonant frequency (Qp), and frequencies above the total peak quality factor frequency (Qmax) and the anti-resonant frequency, up to and beyond the upper stopband edge.

[0194] Figure 18D This is a graphical representation of the power dissipation of a SAW resonator with piezoelectric grooves of different depths normalized relative to the center fundamental frequency, according to aspects of this disclosure. Figure 18D This includes graph 1800D. Graph 1800D includes datasets 1860-1, 1860-2, 1860-3, and 1860-4. In some respects, dataset 1860-1 may be a dataset corresponding to the frequency response of a SAW resonator without PZT (such as the same SAW resonator corresponding to datasets 1830-1, 1840-1, and / or 1850-1). Dataset 1860-2 may be a dataset corresponding to the SAW resonators in datasets 1830-2, 1840-2, and / or 1850-2. Dataset 1860-3 may be a dataset corresponding to the SAW resonators in datasets 1830-3, 1840-3, and / or 1850-3. Dataset 1860-4 may be a dataset corresponding to the SAW resonators in datasets 1830-4, 1840-4, and / or 1850-4.

[0195] In some respects, datasets 1860-1, 1860-2, 1860-3, and 1860-4 may each include peak 1861. Dataset 1860-1 may include peak 1862-1. Dataset 1860-2 may include peak 1862-2. Dataset 1860-3 may include peak 1862-3. Dataset 1860-4 may include peak 1862-4.

[0196] like Figure 18D As shown, as the depth of PZT increases, the peaks corresponding to the upper stopband edge (e.g., peaks 1862-2, 1862-3, and 1862-4) can shift and increase along the spectrum.

[0197] Figure 19A This is a graphical representation comparing the absolute values ​​of the admittances of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure. Figure 19A This includes graph 1900A. Graph 1900A includes datasets 1930-1 and 1930-2. Dataset 1930-1 can be associated with SAW resonators without any PZT. Dataset 1930-2 can be associated with SAW resonators with PZT. Dataset 1930-2 can be associated with SAW resonators with PZT depths between 6% and 24%. In some respects, it corresponds to the previously described... Figures 18A-18D The curves are different. Figures 19A-19D The dataset can be data corresponding to the frequency response of a SAW resonator in terms of absolute frequency. That is, dataset 1930-2 could be a SAW resonator with a PZT, the PZT being designed to have a fundamental resonant frequency to match the fundamental resonant frequency of the SAW resonator in dataset 1930-1 without a PZT, for performance comparison. The reduced speed means that a smaller electrode pitch can be used for resonators with a larger PZT depth to achieve the same resonant frequency. As shown, each of datasets 1930-1 and 1930-2 includes a peak 1931 corresponding to the fundamental resonant frequency. Each of datasets 1930-1 and 1930-2 may also include a peak 1932 corresponding to the anti-resonant frequency.

[0198] like Figure 19A As shown, dataset 1930-1 can also include higher-order resonant mode 1933-1. Dataset 1930-2 can include higher-order resonant mode 1933-2. As shown in the figure, due to the presence of PZT, higher-order resonant mode 1933-2 is shifted in frequency and is higher than higher-order resonant mode 1933-1.

[0199] Figure 19B This is a graphical representation comparing the conductance of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure. Figure 19B This includes graph 1900B. Graph 1900B includes datasets 1940-1 and 1940-2. Dataset 1940-1 can be associated with a SAW resonator without any PZT (such as the SAW resonator corresponding to dataset 1930-1). Dataset 1930-2 can be associated with a SAW resonator with PZT (such as the SAW resonator corresponding to dataset 1930-2). As shown, each of datasets 1940-1 and 1940-2 includes a peak 1941 corresponding to the fundamental resonant frequency.

[0200] like Figure 19B As shown, dataset 1940-1 may also include peak 1942-1 corresponding to the upper stopband edge of the resonator. Dataset 1940-2 may also include peak 1942-2 corresponding to the upper stopband edge of the resonator.

[0201] In some respects, Figure 19B This demonstrates how PZT can help improve signal quality within the passband and significantly shift and / or reduce out-of-band content. For example, the upper stopband edge of peak 1942-2 can be significantly extended upwards along the spectrum. The amplitude of the upper stopband edge of peak 1942-2 is also significantly reduced. As a result, the SAW resonator of 1940-2 can exhibit much less interference to other frequency bands of other filters in the multiplexer. This significantly improves the performance of the multiplexer.

[0202] Figure 19C This is a graphical representation comparing the quality factors of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure. Figure 19C Includes curve 1900C. Curve 1900C includes datasets 1950-1 and 1950-2. In some respects, dataset 1950-1 can be used with SAW resonators without PZT (such as with...). Figure 19A Datasets 1930-1 and / or Figure 19B The dataset 1940-1 corresponds to the frequency response of the same SAW resonator. Dataset 1950-2 can be a dataset corresponding to the SAW resonators in datasets 1930-2 and / or 1940-2. For example... Figure 19C As shown, the quality factor of the SAW resonator increases with the depth of the PZT trench.

[0203] Figure 19D This is a graphical representation comparing the power dissipation of SAW resonators with and without piezoelectric grooves according to aspects of this disclosure. Figure 19DThis includes graph 1900D. Graph 1900D includes datasets 1960-1 and 1960-2. In some respects, dataset 1960-1 can be a dataset corresponding to the frequency response of a SAW resonator without PZT (such as the same SAW resonator corresponding to datasets 1930-1, 1940-1, and / or 1950-1). Dataset 1960-2 can be a dataset corresponding to the SAW resonator of datasets 1930-2, 1940-2, and / or 1950-2.

[0204] In some respects, datasets 1960-1 and 1960-2 may each include peak 1961. Dataset 1960-1 may include peak 1962-1. Dataset 1960-2 may include peak 1962-2. For example... Figure 19D As shown, as the depth of PZT increases, the peak corresponding to the upper stopband edge (e.g., peak 1962-2) can shift and increase along the spectrum.

[0205] Figure 20A It is a graphical representation of the absolute value of the admittance of a SAW resonator with a piezoelectric groove of different depths normalized relative to the center fundamental frequency, according to aspects of this disclosure. Figure 20A This includes graph 2000A. Graph 2000A includes datasets 2030-1 and 2030-2. In some respects, dataset 2030-1 may be a dataset corresponding to the frequency response of a SAW resonator without PZT. Dataset 2030-2 may be a dataset corresponding to the frequency response of a SAW resonator with PZT.

[0206] like Figure 20A As shown, each of datasets 2030-1 and 2030-2 includes a peak 2031 aligned around a normalized fundamental frequency. Each of datasets 2030-1 and 2030-2 also includes an anti-resonant frequency 2032. As shown, the anti-resonant frequencies 2032 can be misaligned, but can be similar. This may slightly reduce the coupling coefficient of the SAW resonator.

[0207] Figure 20B This is a graphical representation of the frequency response of a SAW resonator with piezoelectric grooves of different depths normalized relative to the center fundamental frequency, according to aspects of this disclosure. Figure 20B Includes graph 2000B. Graph 2000B includes datasets 2040-1 and 2040-2. In some respects, dataset 2040-1 can be used with SAW resonators without PZT (such as with...). Figure 20ADataset 2030-1 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 2030-2.

[0208] Similar to curve plot 2000A, the dataset of curve plot 2000B is normalized about the fundamental frequency for comparison. As a result, the peak 2041 of each dataset in datasets 2040-1 and 2040-2 is aligned around the center normalized frequency.

[0209] In some respects, dataset 2040-1 includes peak 2042-1. Peak 2042-1 may correspond to the upper stopband edge of the filter. Dataset 2040-2 includes peak 2042-2. As the depth of PZT increases, the peak corresponding to the upper stopband edge can shift and increase along the spectrum. For example... Figure 20B As shown, the corresponding peak value 2042-2 is significantly higher in frequency than the peak value 2042-1. This offset of the upper stopband edge can remove spurious content from the passband of the filter and other filters, thereby significantly improving signal quality and the performance of the multiplexer circuit.

[0210] It was also noted that the peak value of 2042-2, in addition to its increased frequency shift, also exhibited a lower amplitude. As a result, the degree of spurious content in other frequency bands that could interfere with other filters was significantly reduced, thereby greatly improving signal quality.

[0211] Figure 20C This is a graphical representation of the quality factor of a SAW resonator with piezoelectric grooves of different depths normalized relative to the center fundamental frequency, according to aspects of this disclosure. Figure 20C Includes graph 2000C. Graph 2000C includes datasets 2050-1 and 2050-2. In some respects, dataset 2050-1 can be used with SAW resonators without PZT (such as with...). Figure 20A Dataset 2030-1 and / or Figure 20B Dataset 2040-1 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 2030-2 and / or 2040-2. Figure 20C As shown, the quality factor of the SAW resonator increases with the depth of the PZT trench.

[0212] Figure 20D This is a graphical representation of the power dissipation of a SAW resonator with piezoelectric grooves of different depths normalized relative to the center fundamental frequency, according to aspects of this disclosure. Figure 20DThis includes graph 2000D. Graph 2000D includes datasets 2060-1 and 2060-2. In some aspects, dataset 2060-1 may be a dataset corresponding to the frequency response of a SAW resonator without PZT (such as the same SAW resonator corresponding to datasets 2030-1, 2040-1, and / or 2050-1). Dataset 2060-2 may be a dataset corresponding to the SAW resonator of datasets 2030-2, 2040-2, and / or 2050-2. In some aspects, datasets 2060-1 and 2060-2 may each include peak 2061. Dataset 2060-1 may include peak 2062-1. Dataset 2060-2 may include peak 2062-2. Figure 20D As shown, the peak value 2062-2 is shifted and significantly higher than the peak value 2062-1, and is significantly reduced, thereby significantly improving the performance of the SAW resonator with PZT.

[0213] Figure 21A This is a graphical representation comparing the absolute values ​​of the admittances of SAW resonators without piezoelectric grooves and without modulation pitch, and with and without piezoelectric grooves and modulation pitch, according to aspects of this disclosure. In some aspects, Figures 21A-21D The data shown illustrates the benefits of adding PZT to a SAW resonator in conjunction with electrode pitch modulation. Such pitch modulation can include changing the pitch between electrodes within the same SAW resonator. This can include decreasing or increasing the pitch of the reflector grating, as well as decreasing or increasing the pitch of individual electrode pairs or groups.

[0214] In some respects, pitch modulation can be applied to series resonators but not to parallel resonators. In other respects, pitch modulation can be applied to parallel resonators but not to series resonators. In some respects, SAW resonators with PZT and pitch modulation can be used as both parallel and series resonators.

[0215] like Figure 20B As shown, as previously described, the SAW resonator may include pseudo-content 2070 below the fundamental resonant frequency 2041. This pseudo-content 2070 is sometimes referred to as the beat frequency. This beat frequency, close to the passband of the filter in question, can negatively impact signal quality within the passband. One solution to reduce the amplitude of the pseudo-content 2070 to improve signal quality within the passband is to apply pitch modulation to the SAW resonator. In such cases, the pseudo-content 2070 can be significantly improved, as by... Figure 21BThe dataset 2140-2 shows region 2170. However, a drawback of pitch modulation is that it lowers the frequency of the upper stopband edge of the SAW resonator, which may interfere with the passband of the filter and / or the passband of other filters in the multiplexer circuit. Introducing PZT into the SAW resonator solves this problem, which will be referred to below. Figures 21A-21D To describe in more detail.

[0216] As shown in the figure Figure 21A Includes graph 2100A. Graph 2100A includes datasets 2130-1 and 2130-2. In some respects, dataset 2130-1 may be a dataset corresponding to the frequency response of a SAW resonator without PZT. Dataset 2130-2 may be a dataset corresponding to the frequency response of a SAW resonator with PZT and pitch modulation.

[0217] like Figure 21A As shown, each of datasets 2130-1 and 2130-2 includes a peak 2131 aligned around a normalized fundamental frequency. Each of datasets 2130-1 and 2130-2 also includes an anti-resonant frequency 2132. As shown, the anti-resonant frequencies 2132 can be misaligned, but can be similar. This may slightly reduce the coupling coefficient of the SAW resonator.

[0218] Figure 21B This is a graphical representation comparing the conductance of SAW resonators without piezoelectric grooves and without modulation pitch, as well as those with piezoelectric grooves and those with modulation pitch, according to aspects of this disclosure. Figure 21B Includes curve 2100B. Curve 2100B includes datasets 2140-1 and 2140-2. In some respects, dataset 2140-1 can be used with a SAW resonator without PZT (such as with...). Figure 21A Dataset 2140-2 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 2130-1.

[0219] Similar to curve plot 2100A, the dataset in curve plot 2100B is normalized about the fundamental frequency for comparison. As a result, the peak 2141 of each dataset in datasets 2140-1 and 2140-2 is aligned around the central normalized frequency.

[0220] In some respects, dataset 2140-1 includes peak 2142-1. Peak 2142-1 may correspond to the upper stopband edge of the filter. Dataset 2140-2 includes peak 2142-2 corresponding to the upper stopband edge of a resonator including PZT and pitch modulation. For example... Figure 21B As shown, with Figure 20B Compared to beat frequency 2070, region 2170 is significantly smoothed. This may be due to the introduction of pitch modulation. Figure 21B The result is from a SAW resonator. As previously described, a drawback of pitch modulation is that the upper stopband edge subsequently decreases, which can interfere with the passband. However, apart from pitch modulation, by including PZT in the SAW resonator, this reduction in the frequency of the upper stopband edge has almost no effect on the passband, because... Figure 21B The upper stopband edge, as shown by peak 2142-2, has been significantly removed from the passband and reduced. As a result, the SAW resonator, including pitch modulation and PZT, can include a significantly smooth response below the fundamental frequency 2141 and a significantly smooth response much above the anti-resonant frequency.

[0221] Figure 21C This is a graphical representation comparing the quality factors of SAW resonators without piezoelectric grooves and without modulation pitch, as well as those with piezoelectric grooves and those with modulation pitch, according to aspects of this disclosure. Figure 21C Includes curve 2100C. Curve 2100C includes datasets 2150-1 and 2150-2. In some respects, dataset 2150-1 can be used with a SAW resonator without PZT (such as with...). Figure 21A Dataset 2130-1 and / or Figure 21B Dataset 2150-2 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 2130-2 and / or 2140-2. (The dataset is not directly related to dataset 2140-1.) Figure 21C As shown, the quality factor of the SAW resonator increases with the depth of the PZT trench, and the frequency range with higher quality factor and lower loss increases significantly. Furthermore, compared with... Figure 21C and Figure 20C In contrast, a significant smoothing of the beat frequency was also observed below the fundamental resonant frequency of 1.

[0222] Figure 21D This is a graphical representation comparing the power dissipation of SAW resonators without piezoelectric grooves and without modulation pitch, as well as those with piezoelectric grooves and those with modulation pitch, according to aspects of this disclosure. Figure 21DIncludes graph 2100D. Graph 2100D includes datasets 2160-1 and 2160-2. In some aspects, dataset 2160-1 may be a dataset corresponding to the frequency response of a SAW resonator without PZT (such as the same SAW resonator corresponding to datasets 2130-1, 2140-1, and / or 2150-1). Dataset 2160-2 may be a dataset corresponding to the SAW resonator of datasets 2130-2, 2140-2, and / or 2150-2. In some aspects, datasets 2160-1 and 2160-2 may each include peak 2161. Dataset 2160-1 may include peak 2162-1. Dataset 2160-2 shows that the higher-order peaks of dataset 2160-2 are significantly reduced by PZT and / or pitch modulation to the point that they are almost imperceptible. Figure 21D It also shows a significant reduction in pseudo-content below the fundamental resonant frequency.

[0223] Figure 22 This is a graphical representation comparing the performance of acoustic devices with and without piezoelectric grooves according to aspects of this disclosure. Figure 22 This includes graph 2200A. In some aspects, graph 2200A corresponds to a comparison of the frequency response of a filter including, but not including, a PZT-equipped SAW resonator with a filter including a PZT-equipped SAW resonator and using modulation of the electrode pitch to improve performance. The graph includes data 2200-1 corresponding to the aspect of a filter with a PZT-free SAW resonator and data 2200-2 corresponding to the aspect of a filter with a PZT-equipped SAW resonator.

[0224] Figure 22 Each of the graphs also highlights multiple frequency bands used for mobile communications. For example, band 2210 is shown as corresponding to the passband of a filter. However, the other highlighted frequency bands may correspond to other frequency regions that correspond to the passbands of filters within a multiplexer circuit or any other suitable circuit. These other frequency bands include bands 2211, 2212, 2213, 2214, and 2215.

[0225] As shown in graph 2200A, the frequency response corresponding to a filter without PZT includes the lower band edge 2234-1 and the upper band edge 2236. The frequency response corresponding to a filter with PZT includes the lower band edge 2234-2 and the upper band edge 2236. As shown, one effect of applying PZT to one or more SAW resonators of a filter can include narrowing the filter's passband.

[0226] Similarly, as shown in graph 2200A, the frequency response corresponding to a filter without PZT includes a higher-order mode 2232-1. The frequency response corresponding to a filter with PZT includes a higher-order mode 2232-2. Compared to higher-order mode 2232-1, higher-order mode 2232-2 is located at significantly higher frequencies. Furthermore, in the frequency response of a filter with PZT (2200-2), the upper out-of-band content is typically much smoother.

[0227] Graph 2200B also shows a comparison of the reflection coefficient at port 1 of a filter without PZT with the reflection coefficient at port 1 of a filter with PZT. The lower band edge 2244-1 can, for example, be aligned with the lower band edge 2234-1 in frequency. Similarly, the lower band edge 2244-2 can be aligned with the lower band edge 2234-2 in frequency. The upper band edge 2246 can be aligned with the upper band edge 2236. Furthermore, the decrease in reflection coefficient 2242-1 is shown as being aligned with the higher-order mode 2232-1. Similarly, the decrease in reflection coefficient 2242-2 is shown as being aligned with the higher-order mode 2232-2.

[0228] Graph 2200C also shows a comparison of the power dissipation of the filter without PZT with the corresponding frequency response of the filter with PZT. The peak value of power dissipation 2254-1 can be aligned, for example, with the lower low-frequency band edge 2234-1 in frequency. Similarly, the peak value of power dissipation 2254-2 can be aligned with the lower low-frequency band edge 2234-2 in frequency. The peak value of power dissipation 2256 can be aligned with the upper frequency band edge 2236. In addition, peak value 2252-1 is shown as aligned with the higher-order mode 2232-1. Similarly, peak value 2252-2 is shown as aligned with the higher-order mode 2232-2. As shown in graphs 2200B and 2200C, the out-of-band loss is significantly reduced for the filter with the SAW resonator with PZT (2200-2).

[0229] Graph 2200D shows the conductance of the series resonator within the trapezoidal filter. For example... Figure 22 As shown, peak 2264-1 can be aligned with the center of the passband of filter 2200-1 without PZT. Peak 2264-2 can be aligned with the center of the passband of filter 2200-2 with PZT. As shown in graph 2200D, data 2200-1 includes peak 2262-1 corresponding to the upper stopband edge within passband 2211. Because this peak 2262-1 is both within passband 2211 and has a high amplitude, this can have a significant negative impact on the performance of multiplexers using filters corresponding to passbands 2210 and 2211. However, as Figure 22As shown, a filter with a SAW resonator including a PZT shifts this peak to peak 2262-2. The filter's SAW resonator can be designed such that peak 2262-2 lies between frequency bands, such as between frequency bands 2213 and 2214. Furthermore, the amplitude of peak 2262-2 is significantly reduced compared to the amplitude of peak 2262-1. In this respect, the signal quality of the filter including the SAW resonator with a PZT is significantly improved.

[0230] Graph 2200E shows the conductance of the parallel resonator within the trapezoidal filter. As shown in Graph 2200D, data 2200-1 includes a peak 2272-1. Peak 2272-1 can correspond to the upper stopband edge of a resonator without a PZT. In some cases, this peak 2272-1 can negatively impact the signal quality of the filter. However, as... Figure 22 As shown, a filter with a SAW resonator incorporating a PZT shifts this peak to peak 2272-2. The filter's SAW resonator can be designed such that peak 2272-2 lies between frequency bands, such as between frequency bands 2212 and 2213. Furthermore, the amplitude of peak 2272-2 is significantly reduced compared to the amplitude of peak 2272-1. In this respect, the signal quality of filters and multiplexers incorporating SAW resonators with PZTs is significantly improved.

[0231] Graph 2200F shows the absolute value of the admittance of the series resonator within the trapezoidal filter. For example... Figure 22 As shown, peak 2284-1 is within the passband of filter 2200-1 without PZT. Peak 2284-2 is within the passband of filter 2200-2 with PZT. As shown in graph 2200D, both data 2200-1 and 2200-2 include anti-resonance 2286. This anti-resonance 2286 can be aligned with the notch filter in the filter transmission above the upper stopband edge 2236.

[0232] Graph 2200G shows the absolute values ​​of the admittance of the parallel resonator within the trapezoidal filter. The resonant frequencies (2294-1, 2294-2) and anti-resonant frequencies (2296-1, 2296-2) correspond to the expected characteristics in the transmission (2000A) and reflection (2200B) of the corresponding filter.

[0233] Figure 23 This is a cross-sectional side view of a SAW resonator 2300 having piezoelectric grooves 2371 according to an aspect of this disclosure. Figure 23As shown, PZT can be configured according to any suitable geometry. For example, PZT can be configured within the upper surface of the piezoelectric film of the SAW resonator, or within the lower surface of the piezoelectric film of the SAW resonator, or within both the upper and lower surfaces of the piezoelectric film of the SAW resonator.

[0234] SAW resonator 2300 may be similar to the SAW resonators previously described. Specifically, SAW resonator 2300 may include a piezoelectric film 2334. Piezoelectric film 2334 may be similar to the piezoelectric film previously described. In some aspects, piezoelectric film 2334 may be positioned on dielectric layer 2335. Figure 23 As shown, dielectric layer 2335 can be positioned on layers 2336 and 2337. The SAW resonator 2300 may also include multiple electrodes 2322. Electrodes 2322 may be similar to the electrodes previously described.

[0235] The SAW resonator 2300 includes the PZT 2371. In Figure 23 In the example shown, PZT 2371 can be a lower PZT or a PZT formed within the lower surface of the piezoelectric film 2334. PZT 2371 can be positioned between electrodes 2322, such as... Figure 23 As shown. A similar lower PZT can be positioned between the other electrodes of the SAW resonator 2300. PZT 2371 and any lower PZT can be similar to any upper PZT described herein. For example, the lower PZT can have any suitable shape or size. In one aspect, the lower PZT 2371 may include a tapered edge or shoulder. For example, the edge of the lower PZT 2371 may taper gradually at the angle 2378 shown. In some aspects, the SAW resonator including the lower PZT (such as lower PZT 2371) may alternatively be described as including a dielectric trench. For example, the SAW resonator 2300 includes a dielectric trench 2373. In some aspects, the dielectric trench 2373 may include an edge inclined at an angle 2378. In some aspects, the dielectric trench 2373 includes an upper width 2376 and a lower width 2374. In some respects, the dielectric trench 2371 and / or the lower piezoelectric trench 2371 may have a depth 2372.

[0236] exist Figure 23 In the example shown, dielectric layer 2335 may have a thickness of 2350. Piezoelectric film 2334 may have a thickness of 2340. In some aspects, electrode 2322 may have a thickness of 2330. The width of electrode 2322 may be a width of 2332, and electrodes 2322 may be spaced apart according to pitch 2342.

[0237] exist Figure 23In the example shown, the dielectric trench can be aligned with electrode 2322. In other words, the dielectric trench can be positioned below electrode 2322. Similarly, the lower PZT, such as lower PZT 2371, can be aligned with the gap between electrodes 2322 (such as gap 2370). In other words, the lower PZT can be positioned below the gap or space between electrodes 2322.

[0238] Figure 24A This is a graphical representation of the absolute values ​​of the admittance of SAW resonators with piezoelectric trenches of different orientations according to aspects of this disclosure. In some aspects, Figures 24A-24D The data shown illustrates the advantages of SAW resonators with a lower PZT over SAW resonators with an upper PZT.

[0239] In some respects, the lower PZT can be applied to series resonators but not to parallel resonators. In other respects, the lower PZT can be applied to parallel resonators but not to series resonators. In some respects, SAW resonators with upper and / or lower PZTs can be used as both parallel and series resonators.

[0240] As shown in the figure Figure 24A This includes graph 2400A. Graph 2400A includes datasets 2430-1 and 2430-2. In some respects, dataset 2430-1 may be a dataset corresponding to the frequency response of a SAW resonator with an upper PZT. Dataset 2430-2 may be a dataset corresponding to the frequency response of a SAW resonator with the same shape and orientation but with a reversed lower PZT.

[0241] like Figure 24A As shown, each of datasets 2430-1 and 2430-2 includes a peak 2431 aligned around the fundamental frequency. Each of datasets 2430-1 and 2430-2 also includes an anti-resonant frequency 2432. As shown, the anti-resonant frequencies 2432 can be misaligned, but can be similar. This may result in a slightly increased coupling of the SAW resonator with a lower PZT compared to the SAW resonator with an upper PZT. In some respects, the SAW resonator with a lower PZT can exhibit higher capacitance compared to the SAW resonator with an upper PZT. Greater coupling and greater capacitance benefit the resulting resonator and filter, leading to improved performance and smaller size.

[0242] Figure 24B This is a graphical representation of the conductance of a SAW resonator with piezoelectric grooves having different orientations according to aspects of this disclosure. Figure 24BIncludes curve 2400B. Curve 2400B includes datasets 2440-1 and 2440-2. In some respects, dataset 2440-1 can be used with a SAW resonator with an upper PZT (such as with...). Figure 24A Dataset 2440-2 can be a dataset corresponding to the frequency response of the same SAW resonator as dataset 2430-1.

[0243] Similar to graph 2400A, the datasets in graph 2400B are centered around the same fundamental frequency for comparison. As a result, the peak 2441 of each dataset in datasets 2440-1 and 2440-2 is aligned around the center frequency.

[0244] In some respects, dataset 2440-1 includes peak 2442-1. Peak 2442-1 can correspond to the upper stopband edge of a SAW resonator with an upper PZT. Dataset 2440-2 includes peak 2442-2 corresponding to the upper stopband edge of a SAW resonator with a lower PZT. In this way, compared to a SAW resonator with an upper PZT, a SAW resonator with a lower PZT allows the upper stopband edge to be extended to higher frequencies, which can be beneficial for improving performance.

[0245] Figure 24C This is a graphical representation of the quality factor of a SAW resonator with piezoelectric grooves having different orientations according to aspects of this disclosure. Figure 24C Includes curve 2400C. Curve 2400C includes datasets 2450-1 and 2450-2. In some respects, dataset 2450-1 can be used with a SAW resonator with an upper PZT (such as with...). Figure 24A Dataset 2430-1 corresponds to the frequency response of the same SAW resonator. Dataset 2450-2 can be a dataset corresponding to a SAW resonator with a lower PZT. Figure 24C As shown, the quality factor of a SAW resonator with a lower PZT can be greater than that of a SAW resonator with a lower PZT. In this respect, the choice between using an upper or lower PZT may be a design option.

[0246] Figure 24D This is a graphical representation of the power dissipation of SAW resonators with different orientations of piezoelectric grooves according to aspects of this disclosure. Figure 24DThis includes graph 2400D. Graph 2400D includes datasets 2460-1 and 2460-2. In some aspects, dataset 2460-1 may be a dataset corresponding to the frequency response of a SAW resonator with an upper PZT (such as the same SAW resonator corresponding to datasets 2430-1, 2440-1, and / or 2450-1). Dataset 2460-2 may be a dataset corresponding to a SAW resonator with a lower PZT (such as the SAW resonator in datasets 2430-2, 2440-2, and / or 2450-2). In some aspects, datasets 2460-1 and 2460-2 may each include a peak 2461. Dataset 2460-1 may include a peak 2462-1. Dataset 2460-2 shows that the peak 2462-2 of dataset 2460-2 is offset in frequency and is higher than the peak 2462-1, both of which correspond to the upper stopband edge of the resonator.

[0247] Figure 25 This is a cross-sectional side view of a SAW resonator with piezoelectric grooves according to aspects of this disclosure. Figure 25 As shown, the lower PZT can be positioned at any suitable location relative to the electrodes of the SAW resonator device.

[0248] SAW resonator 2500 may be similar to the SAW resonators previously described. Specifically, SAW resonator 2500 may include a piezoelectric film 2534. Piezoelectric film 2534 may be similar to the piezoelectric films previously described. In some aspects, piezoelectric film 2534 may be positioned on dielectric layer 2535. Figure 25 As shown, dielectric layer 2535 can be positioned on layers 2536 and 2537. The SAW resonator 2500 may also include multiple electrodes 2522. Electrodes 2522 may be similar to the electrodes previously described.

[0249] The SAW resonator 2500 includes the PZT 2571. In Figure 25 In the example shown, PZT 1271 can be the lower PZT. For example... Figure 25As shown, the lower PZT 2571 can be positioned below the electrode 2522. On one hand, the lower PZT 2571 may include a tapered edge or shoulder. For example, the edge of the lower PZT 2571 may taper gradually at the angle 2578 shown. In some aspects, the SAW resonator including the lower PZT (as in the lower PZT 2571) may alternatively be described as including a dielectric trench. For example, the SAW resonator 2500 includes a dielectric trench 2573. In some aspects, the dielectric trench 2573 may include an edge angled at angle 2578. In some aspects, the dielectric trench 2573 includes an upper width 2576 and a lower width 2574. In some aspects, the dielectric trench 2573 and / or the lower piezoelectric trench 2571 may have a depth 2572.

[0250] exist Figure 25 In the example shown, dielectric layer 2535 may have a thickness of 2550. Piezoelectric film 2534 may have a thickness of 2540. In some aspects, electrode 2522 may have a width of 2530. The width of electrode 2522 may be a width of 2532, and electrodes 2522 may be spaced apart according to pitch 2542.

[0251] exist Figure 25 In the example shown, the dielectric trench can be positioned between electrodes 2522 or aligned with gap 2570. Similarly, the lower PZT, such as lower PZT 2571, can be aligned with electrode 2522. In other words, the lower PZT can be positioned below electrode 2522.

[0252] Figure 26 This is a graphical representation of the relationship between the piezoelectric trench depth and the performance of the SAW resonator according to aspects of this disclosure. As previously mentioned, the material chosen for this example can be a suitably oriented lithium tantalate, thereby primarily exciting shear-level acoustic modes. The thickness can be thin enough to ensure a large coupling factor, a large quality factor, and suppression of spurious modes. The piezoelectric layer can be located on a suitable thin layer on top of the silicon wafer. As previously mentioned, other material choices are also possible. In some aspects, Figure 26 Includes graph 2600A. Graph 2600A shows the relationship between the piezoelectric trench depth and the resonant frequency of the SAW resonator. Graph 2600A includes an x-axis 2602A corresponding to the trench depth and a y-axis 2604A corresponding to the resonant frequency. Multiple data points 2606A are included in graph 2600A.

[0253] Figure 26It also includes graph 2600B. Graph 2600B shows the relationship between the piezoelectric trench depth and the resonant frequency of the SAW resonator. Graph 2600B includes an x-axis 2602B corresponding to the trench depth and a y-axis 2604B corresponding to the stopband width (SBW). Multiple data points 2606B are included in graph 2600B.

[0254] Figure 26 It also includes graph 2600C. Graph 2600C shows the relationship between the piezoelectric trench depth and the resonant frequency of the SAW resonator. Graph 2600C includes an x-axis 2602C corresponding to the trench depth and a curve corresponding to the maximum quality factor (BQ). max The corresponding y-axis is 2604C. Multiple data points 2606C are included in the curve plot 2600C.

[0255] Figure 26 It also includes graph 2600D. Graph 2600D shows the relationship between the piezoelectric trench depth and the coupling coefficient of the SAW resonator. Graph 2600D includes an x-axis 2602D corresponding to the trench depth and a y-axis 2604D corresponding to the coupling coefficient (k2e). Multiple data points 2606D are included in graph 2600D.

[0256] Figure 27 This is a graphical representation of the relationship between the piezoelectric trench depth and the performance of the SAW resonator according to aspects of this disclosure. In some aspects, Figure 27 Includes graph 2700A. Graph 2700A shows the relationship between the piezoelectric trench depth and the capacitance per unit area of ​​the SAW resonator. Graph 2700A includes an x-axis 2702A corresponding to the trench depth and a y-axis 2704A corresponding to the capacitance per unit area. Multiple data points 2706A are included in graph 2700A.

[0257] Figure 27 This also includes graph 2700B. Graph 2700B shows the relationship between the piezoelectric trench depth and the frequency difference between the resonant frequency fs and the anti-resonant frequency fp of the SBW and SAW resonators. Graph 2700B includes an x-axis 2702B corresponding to the trench depth and a y-axis 2704B corresponding to the ratio of SBW to fs / fp. Multiple data points 2706B are included in graph 2700B. A ratio greater than 2 means that USBE will be outside the passband. The larger the ratio, the larger the relative frequency range within the stopband of the resonator.

[0258] Figure 27It also includes graph 2700C. Graph 2700C shows the relationship between the piezoelectric trench depth and the quality factor of the SAW resonator at its anti-resonant frequency. Graph 2700C includes an x-axis 2702C corresponding to the trench depth and a y-axis 2704C corresponding to the quality factor (BQp) at the anti-resonant frequency. Multiple data points 2706C are included in graph 2700C.

[0259] Figure 28 The piezoelectric trench edge angle α is based on aspects of this disclosure. PZT (See example) Figure 11 A graphical representation of the relationship between the angle 1178 and the performance of the SAW resonator. In some aspects, Figure 28 This includes graph 2800A. Graph 2800A shows the relationship between the edge angle of the piezoelectric trench and the resonant frequency of the SAW resonator. The edge angle of the piezoelectric trench can be determined by... Figure 28 α in PZT As shown. Graph 2800A includes an x-axis 2802A corresponding to the trench edge angle and a y-axis 2804A corresponding to the resonant frequency. Multiple data points 2806A are included in graph 2800A. Increasing the angle increases the resonant frequency.

[0260] Figure 28 This also includes graph 2800B. Graph 2800B shows the relationship between the angle of the piezoelectric trench edge and the total capacitance per unit area of ​​the SAW resonator. Graph 2800B includes an x-axis 2802B corresponding to the trench edge angle and a y-axis 2804B corresponding to the total capacitance per unit area. Multiple data points 2806B are included in graph 2800B. Increasing the angle increases the total capacitance per unit area.

[0261] Figure 28 This also includes graph 2800C. Graph 2800C shows the relationship between the angle of the piezoelectric trench edge and the coupling of the SAW resonator. Graph 2800C includes an x-axis 2802C corresponding to the trench edge angle and a y-axis 2804C corresponding to the coupling. Multiple data points 2806C are included in graph 2800C. Increasing the angle can increase the coupling. The optimal angle in this regard may be 120°.

[0262] Figure 29This is a cross-sectional side view of a SAW resonator 2900 according to an aspect of this disclosure, wherein a sacrificial layer 2924 is positioned over electrodes 2922. Specifically, the SAW resonator 2900 includes a piezoelectric film 2930. The piezoelectric film 2930 may be positioned over a dielectric layer 2935. In some aspects, the SAW resonator 2900 may also include layers 2940 and 2945, which may be similar to any layer described herein. The SAW resonator 2900 includes a plurality of electrodes 2922. The sacrificial layer 2924 may be positioned over each electrode 2922. In some aspects, the thickness of the electrodes 2922 may be a thickness 2950, ​​and the thickness of the piezoelectric film 2930 may be a thickness 2960. In some aspects, the SAW resonator 2900 may be a SAW resonator prior to a PAS-free trimming process using an ion beam or ion plasma. In some aspects, the SAW resonator 2900 may include the sacrificial layer 2924 to prevent material from being removed from the electrodes 2922. In this respect, after the PAS trimming process, the electrodes 2922 of the SAW resonator 2900 can have the same thickness 2950, ​​but the piezoelectric film 2960 between the electrodes 2922 can have a reduced thickness, thereby forming PZT in the upper surface of the piezoelectric film 2930 without changing the thickness of the electrodes 2922.

[0263] Figure 30 This is a graphical representation of graph 3000, illustrating the relationship between the piezoelectric cutting 3002 and the effective coupling k2e 3004 of the main mode (shearing mode SM) and pseudo mode (Rayleigh mode RM) according to aspects of this disclosure. Figure 30 As shown, the cutting of the piezoelectric layer can alter the coupling of pseudomodes. Depending on the type and thickness of the piezoelectric layer, the material type of the substrate, the material type and thickness of the intermediate layer, the depth of the PZT, and other material and geometric factors, a crystal orientation that minimizes the excitation of pseudomodes can be found. For LT, an orientation close to 30° YX can, in some cases, lead to the minimization of Rayleigh-type pseudoacoustic mode excitation while simultaneously generating a large coupling value for the sheared master mode, and the coupling between the master mode and pseudomodes may vary with crystal orientation (or cutting). In some respects, the optimized cutting can be varied according to the specific properties of the SAW resonator. For example, the optimized cutting corresponding to minimum pseudomode coupling can be greater than or less than 30 degrees.

[0264] Figure 31 This is a graphical representation of the performance comparison of SAW devices having piezoelectric trenches on a piezoelectric layer with optimized crystal orientation and on a piezoelectric layer with unoptimized crystal orientation, according to aspects of this disclosure. Figure 31This includes graph 3100A. In some aspects, graph 3100A corresponds to a comparison of the transmission of a filter (such as a trapezoidal filter) including a SAW resonator with piezoelectric grooves and optimized crystal orientation with the frequency response of a filter including a SAW resonator with piezoelectric grooves and unoptimized crystal orientation. These graphs include data 3100-1 corresponding to a device with piezoelectric grooves and optimized crystal orientation, and data 3100-2 corresponding to a device with piezoelectric grooves and unoptimized crystal orientation.

[0265] In some respects, it can be based on references Figure 30 The described technique determines the piezoelectric crystal orientation of the filter corresponding to data 3100-2. In some aspects, the crystal orientation can be 30° YX. In some aspects, such as Figure 31 As shown, this choice of crystal orientation (sometimes referred to as cleaving) can substantially suppress master pseudomodes (such as Rayleigh modes (“RM”). This cleaving can also excite master modes (shear modes (“SM”) that are stronger than those of a typical standard cleaving. In some respects, devices with piezoelectric grooves on a standard-cut piezoelectric layer can be shown by data 3100-1.

[0266] Figure 31 Each of the graphs also highlights multiple frequency bands. For example, band 3110 is shown, corresponding to the passband of the filter. However, the other highlighted frequency bands may correspond to other filters in a multiplexer circuit or any other suitable circuit. In the example shown, these other frequency bands include bands 3109 and 3111.

[0267] As shown in graph 3100A, the frequency response corresponding to the filter based on the unoptimized piezoelectric crystal orientation includes the lower band edge 3134-2 and the upper band edge 3136. The frequency response corresponding to the filter based on the optimized piezoelectric crystal orientation includes the lower band edge 3134-1 and the upper band edge 3136.

[0268] Similarly, as shown in graph 3100A, the frequency response corresponding to the filter based on the unoptimized piezoelectric crystal orientation includes pseudo-modes 3132 and 3133. The frequency response corresponding to the filter based on the optimized piezoelectric crystal orientation does not exhibit these pseudo-modes, or these pseudo-modes are significantly suppressed.

[0269] Graph 3100B also shows a comparison of the reflection coefficients corresponding to a filter based on an unoptimized piezoelectric crystal orientation with those corresponding to a filter based on an optimized piezoelectric crystal orientation. The lower band edge 3144-1 can, for example, be aligned with the lower band edge 3134-1 in frequency. Similarly, the lower band edge 3144-2 can be aligned with the lower band edge 3134-2 in frequency. The upper band edge 3146 can be aligned with the upper band edge 3136. Additionally, peak 3142 is shown aligned with pseudo-mode 3132, while peak 3143 is shown aligned with pseudo-mode 3133.

[0270] Graph 3100C also shows a comparison of the dissipation power corresponding to a filter based on an unoptimized piezoelectric crystal orientation with the dissipation power corresponding to a filter based on an optimized piezoelectric crystal orientation. The peak of dissipation power 3154-1 can, for example, be aligned with the lower band edge 3134-1 in frequency. Similarly, the peak of dissipation power 3154-2 can be aligned with the lower band edge 3134-2 in frequency. The peak of dissipation power 3156 can be aligned with the upper band edge 3136. In addition, the peak value of dissipation power 3152 is shown as aligned with the pseudo-mode 3132. Similarly, the peak value of dissipation power 3153 is shown as aligned with the pseudo-mode 3133. As shown in graphs 3100B and 3100C, for a filter with an optimized piezoelectric crystal orientation (3100-2) and a SAW resonator with optimized PZT, the out-of-band content due to the pseudo-mode is significantly reduced.

[0271] Graph 3100D shows the conductance of the series resonator within the trapezoidal filter. For example... Figure 31 As shown, peak 3164-1 can be aligned with the center of the passband of the unoptimized filter 3100-1. Peak 3164-2 can be aligned with the center of the passband of the optimized filter 3100-2. As shown in graph 3100D, data 3100-1 includes peak 3162. This peak 3162 can negatively impact the performance of the multiplexer. However, as shown in graphs 3100B and 3100C, filters with SAW resonators significantly reduce this peak, which include optimized PZT using optimized piezoelectric crystal orientation.

[0272] Graph 3100E shows the conductance of the parallel resonator within the trapezoidal filter. As shown in Graph 3100E, data 3100-1 includes a peak of 3172. This peak of 3172 can negatively impact the performance of the multiplexer. However, as shown in Graphs 3100B and 3100C, filters with SAW resonators significantly reduce this peak, which incorporate optimized PZT using optimized piezoelectric crystal orientation.

[0273] Graph 3100F shows the absolute value of the admittance of the series resonator within the trapezoidal filter. For example... Figure 31 As shown, peak 3184-1 can be aligned with the center of the passband of filter 3100-1. Peak 3184-2 can be aligned with the center of the passband of filter 3100-2. As shown in graph 3100D, both data 3100-1 and 3100-2 include anti-resonance 3186.

[0274] Graph 3100G shows the absolute values ​​of the admittance of the parallel resonators within the trapezoidal filter. Anti-resonance 3196-1 can be aligned with the center of the passband of filter 3100-1. Anti-resonance 3194-2 can be aligned with the center of the passband of filter 3100-2.

[0275] An aspect of the invention includes an embodiment comprising an acoustic resonator having a master mode with shear horizontal displacement, wherein the piezoelectric film is made of lithium tantalate, wherein the cut angle is between 15 and 60 xY and the thickness is less than 5λ. In some embodiments, the piezoelectric film may be made of lithium tantalate, wherein the cut angle is between 20 and 42 xY and the thickness is less than 5λ. In some embodiments, the piezoelectric film may be made of lithium tantalate, wherein the cut angle is 30 xY and the thickness is less than 5λ. In some embodiments, the piezoelectric film may be made of lithium tantalate, wherein the cut angle is 30 xY and the thickness is less than 1λ. In some embodiments, the piezoelectric film may be made of lithium tantalate, wherein the cut angle is 30 xY and the thickness is between 5% and 60% of λ. In some embodiments, the piezoelectric film may be made of lithium tantalate, wherein the cut angle is 30 xY and the thickness is between 10% and 50% of λ. In some embodiments, the piezoelectric film may be made of lithium tantalate, wherein the cut angle is 30 xY and the thickness is between 15% and 30% of λ. In some embodiments, the acoustic resonator includes a layer beneath a piezoelectric thin film, the layer being made of silicon oxide and having a thickness less than 5λ. In some embodiments, the acoustic resonator includes a layer beneath a piezoelectric thin film, the layer being made of silicon oxide and having a thickness less than 1λ. In some embodiments, the acoustic resonator includes a layer beneath a piezoelectric thin film, the layer being made of silicon oxide and having a thickness between 15% and 30% of λ. While these ranges are provided herein for illustrative purposes, it is entirely contemplated that the layer including the piezoelectric thin film and the layer beneath it can have any suitable thickness and any suitable angle or cut. In some embodiments, the acoustic resonator may include a substrate. In some embodiments, the substrate may be made of silicon, silicon carbide, quartz, sapphire, diamond, or any other material. In some aspects, λ may represent the wavelength of the wave motion, excitation, or acoustic energy corresponding to the acoustic resonator.

[0276] Those skilled in the art will recognize that the apparatus, systems, and methods described above can be modified in various ways. Therefore, those skilled in the art will understand that the embodiments covered by this disclosure are not limited to the specific exemplary embodiments described above. In this regard, although illustrative embodiments have been shown and described, a wide range of modifications, alterations, and substitutions are disclosed in the foregoing with full consideration. It should be understood that such modifications may be made above without departing from the scope of this disclosure. Therefore, it should be understood that the appended claims should be interpreted broadly and in a manner consistent with this disclosure.

Claims

1. A surface acoustic wave (SAW) resonator device, comprising: The first electrode is positioned on the upper surface of the piezoelectric film; The second electrode is positioned on the upper surface of the piezoelectric film; as well as A first piezoelectric trench (PZT) is positioned between the first electrode and the second electrode. The first PZT includes a recess in the piezoelectric film and has a first trench depth.

2. The SAW resonator device according to claim 1, wherein the first PZT is an upper PZT formed within the upper surface of the piezoelectric film.

3. The SAW resonator device according to claim 1, wherein the first PZT is a lower PZT formed within the lower surface of the piezoelectric film.

4. The SAW resonator device according to claim 1, wherein the first trench depth of the first PZT is in the range of 0% to 100% of the thickness of the piezoelectric film.

5. The SAW resonator device according to claim 4, wherein 100% of the trench depth corresponds to a fully etched PZT.

6. The SAW resonator device of claim 1, wherein the first trench depth of the first PZT is in the range of 1 nm to 50 nm.

7. The SAW resonator device of claim 1, wherein the first PZT is centrally aligned between the first electrode and the second electrode.

8. The SAW resonator device of claim 1, wherein the piezoelectric film is positioned on one or more dielectric layers, and the one or more dielectric layers are positioned on a substrate.

9. The SAW resonator device of claim 1, wherein the first PZT includes a lower width corresponding to the width of the first PZT at the bottom of the PZT and an upper width corresponding to the width of the first PZT at the top of the first PZT.

10. The SAW resonator device of claim 9, wherein the upper width is greater than the lower width.

11. The SAW resonator device of claim 1, wherein the first PZT is symmetrical about an axis parallel to the first electrode.

12. The SAW resonator device according to claim 1, wherein the first PZT includes a first tilt region corresponding to a first angle and a second tilt region corresponding to a second angle.

13. The SAW resonator device of claim 1, further comprising a second PZT and a third PZT, the second PZT being positioned within the piezoelectric film on the side of the first electrode opposite to the first PZT, such that a first piezoelectric platform having a first width is formed between the first PZT and the second PZT, and the third PZT being positioned within the piezoelectric film on the side of the second electrode opposite to the first PZT, such that a second piezoelectric platform having a second width is formed between the first PZT and the third PZT.

14. The SAW resonator device of claim 13, wherein the width of the first electrode is equal to the first width of the first piezoelectric platform.

15. The SAW resonator device of claim 13, wherein the width of the first electrode is smaller than the first width of the first piezoelectric platform.

16. The SAW resonator device of claim 13, wherein the width of the first electrode is greater than the first width of the first piezoelectric platform.

17. The SAW resonator device of claim 13, wherein the first electrode is centered and aligned with the first platform.

18. The SAW resonator device of claim 1, wherein the piezoelectric film is positioned on a Bragg mirror.

19. The SAW resonator of claim 1, wherein the piezoelectric film is positioned on the piezoelectric substrate.

20. The SAW resonator of claim 19, wherein the piezoelectric film and the piezoelectric substrate are made of the same material type and the same material orientation.

21. The SAW resonator device according to claim 1, wherein the piezoelectric film is a freestanding piezoelectric film.

22. The SAW resonator device of claim 1, wherein the SAW resonator device is part of a trapezoidal filter.

23. The SAW resonator device of claim 1, wherein the SAW resonator device is part of a coupled resonator filter.

24. The SAW resonator device of claim 1, wherein the thickness of the piezoelectric layer is less than about five times the wavelength of the sound wave.

25. The SAW resonator device of claim 1, wherein the thickness of the piezoelectric layer is about 5% to about 60% of the wavelength of the acoustic wave.

26. The SAW resonator device of claim 1, wherein the piezoelectric element comprises lithium tantalate.

27. The SAW resonator device of claim 1, wherein the piezoelectric element comprises lithium tantalate, wherein the orientation is between about Y+0° and about Y+60° and propagates along the x-axis of the crystal.

28. The SAW resonator device of claim 1, wherein the piezoelectric element comprises lithium niobate.

29. The SAW resonator device of claim 1, wherein the piezoelectric element comprises lithium niobate, wherein the orientation is generally between about Y-20° and about Y+60° and propagates along the x-axis of the crystal.

30. A surface acoustic wave (SAW) resonator device comprising: A plurality of electrodes, said plurality of electrodes being positioned on the upper surface of a piezoelectric film having a first thickness; and Multiple piezoelectric trenches (PZTs) are formed within the piezoelectric film between the multiple electrodes, wherein the multiple PZTs correspond to a region of the piezoelectric film having a second thickness, which is less than the first thickness.

31. The SAW resonator device of claim 30, wherein the plurality of electrodes are spaced apart from each other by a first pitch, and the plurality of PZTs are spaced apart from each other by a second pitch.

32. The SAW resonator device of claim 31, wherein the first pitch is different from the second pitch.

33. The SAW resonator device of claim 30, wherein the plurality of electrodes are spaced apart by a modulation pitch such that two or more electrodes of a first subset are spaced apart by a first pitch, and two or more interdigital transducers of a second subset are spaced apart by a second pitch.

34. A method for modifying a surface acoustic wave (SAW) resonator device, the method comprising: Receive the SAW resonator device; and An ion plasma is applied to the upper surface of the SAW resonator device, reducing the thickness of one or more interdigital transducers and forming piezoelectric grooves between the one or more interdigital transducers.

35. A method comprising: A receiving surface acoustic wave (SAW) resonator device, the device comprising: piezoelectric film; An interdigital transducer, the interdigital transducer comprising a plurality of interleaved electrodes positioned on the piezoelectric film; as well as A sacrificial layer, wherein the sacrificial layer is positioned on the plurality of interleaved electrodes; as well as An ion beam is applied to the upper surface of the SAW resonator device, causing the sacrificial layer to be removed and piezoelectric trenches (PZTs) to be formed between the plurality of interleaved electrodes.

36. The method of claim 35, further comprising: Patterning the plurality of interleaved electrodes located on the piezoelectric film; and The sacrificial layer located on the plurality of interleaved electrodes is patterned.

37. The method of claim 36, wherein the interleaved electrodes and sacrificial material are patterned by sputtering, photolithography and dry etching.

38. The method of claim 36, wherein the interleaved electrodes and sacrificial material are patterned by sputtering, material deposition, and stripping.

39. A method comprising: A receiving surface acoustic wave (SAW) resonator device, the device comprising: piezoelectric film; and An interdigital transducer, the interdigital transducer comprising a plurality of electrodes; and A wet etching process is applied to the upper surface of the SAW resonator device, reducing the thickness of the plurality of electrodes and forming one or more piezoelectric trenches (PZTs) between the plurality of electrodes.

40. A method comprising: A receiving surface acoustic wave (SAW) resonator device, the device comprising: piezoelectric film; and An interdigital transducer, the interdigital transducer comprising a plurality of electrodes; and A wet etching process is applied to the lower surface of the SAW resonator device, reducing the thickness of the plurality of electrodes and forming one or more piezoelectric trenches (PZTs) between the plurality of electrodes.

41. The method of claim 40, wherein the piezoelectric film is bonded to a substrate (handle) using one or more intermediate layers.

42. The method of claim 41, further comprising: The first dielectric layer is positioned below the piezoelectric film; Position the second dielectric layer on the top surface of the substrate wafer; and The first dielectric layer and the second dielectric layer are bonded together.

43. The method of claim 42, further comprising planarizing the bottom surface of the piezoelectric film before bonding the first dielectric layer and the second dielectric layer.

44. The method of claim 43, wherein the planarization of the bottom surface of the piezoelectric film is performed by wet etching.

45. The method of claim 43, wherein the planarization of the bottom surface of the piezoelectric film is performed by dry etching.

46. ​​The method of claim 43, wherein the planarization of the bottom surface of the piezoelectric film is performed by removing material with ion plasma.

47. The method of claim 43, wherein the planarization of the bottom surface of the piezoelectric film is performed by chemical mechanical polishing.

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