Solidly mounted lamÉ mode micro-acoustic resonators and related fabrication methods

Abstract

A micro-acoustic resonator includes a piezoelectric layer solidly mounted on a layer stack (610), including a bottom electrode (616) and an acoustic mirror (612). The micro-acoustic resonator has a crystalline structure that may be excited in a Lame mode by an interdigital transducer, IDT, structure (602) on the piezoelectric layer. A resonant frequency of the micro-acoustic resonator is dependent on a thickness of the piezoelectric layer and dimensions of the IDT structure. Solidly mounting a piezoelectric layer operative in a Lame mode on an acoustic mirror increases effective electromechanical coupling and reduces acoustic losses. The bottom electrode provides a lower boundary for the electric fields created by the IDT structure to assist in containing the electric field and exciting the piezoelectric layer with increased efficiency. In some examples, the bottom electrode is an unpatterned continuous metal layer between the IDT structure and the acoustic mirror.

Description

Qualcomm Ref No. 2407752 1SOLIDLY MOUNTED LAME MODE MICRO-ACOUSTIC RESONATORS AND RELATED FABRICATION METHODSPRIORITY APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application Serial No. 63 / 707,899, filed October 16, 2024 and entitled “SOLIDLY MOUNTED LAME MODE MICRO-ACOUSTIC RESONATORS AND RELATED FABRICATION METHODS,” which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The technology of the disclosure relates generally to wireless transceivers and other components that employ acoustic filters and, more specifically, to micro-acoustic filters employing Lame mode resonators.BACKGROUND

[0003] Electronic devices may use radio-frequency (RF) signals to communicate information that enables voice communication, uploading and downloading of media (e g., audio and video), remote control of household devices, and reception of global positioning information, for example. To transmit or receive the RF signals within a given frequency band allocated for such communications, the electronic device may use filters that pass signals within the frequency band and suppress (e.g., attenuate) jammers or noise at frequencies outside of the frequency band. It can be challenging, however, to design and manufacture a filter that provides filtering for RF applications, especially those that operate at frequencies above two (2) gigahertz (GHz) with high energy efficiency.SUMMARY

[0004] Aspects disclosed in the detailed description include solidly mounted Lame mode micro-acoustic resonators. Related methods of fabricating a solidly mounted Lame mode micro-acoustic resonator are also disclosed. As the frequencies of telecommunications (e g., 4G, 5G, and 6G) increase over time, there is an increased need to develop micro-acoustic devices in which the efficiencies and frequencies of operation are not limited by the dimensions of their physical features, such as film thicknesses and electrode widths. An exemplary micro-acoustic resonator includes a piezoelectric layerWT Ref No. 1173-952Qualcomm Ref No. 2407752 2 that is excitable in a Lame mode by an interdigital transducer (IDT) structure and solidly mounted on an acoustic mirror and bottom electrode to provide increased effective electromechanical coupling. A resonant frequency depends on a width and spacing of the fingers of an IDT structure as well as a thickness of the piezoelectric layer. The bottom electrode may assist in containing the electric field that excites the piezoelectric layer to increase efficiency. An acoustic mirror, as employed in bulk acoustic wave devices, is employed to reduce acoustic losses.

[0005] In this regard, in one aspect, a micro-acoustic filter is disclosed. The microacoustic filter includes a substrate and an acoustic mirror on the substrate. The microacoustic filter also includes a piezoelectric layer having a crystalline structure operative to excite a Lame mode, a bottom electrode disposed between the acoustic mirror and a first side of the piezoelectric layer, and an IDT structure comprising a first electrode, and a second electrode disposed on the piezoelectric layer

[0006] In another aspect, a method of fabricating a micro-acoustic filter is disclosed. The method includes forming an acoustic mirror on a substrate, forming a bottom electrode on the acoustic mirror, forming a piezoelectric layer on the bottom electrode, the piezoelectric layer having a crystalline structure operative to excite a Lame mode and forming an IDT structure comprising a first electrode and a second electrode disposed on the piezoelectric layer.

[0007] In another aspect, a wireless transceiver is disclosed. The wireless transceiver includes a plurality of micro-acoustic resonators, each microacoustic resonator of the plurality of micro-acoustic resonators comprising an acoustic mirror, a piezoelectric layer having a crystalline structure operative to excite a Lame mode, a bottom electrode layer disposed between the acoustic mirror and a first side of the piezoelectric layer and an IDT structure comprising a first electrode and a second electrode disposed on a second side of the piezoelectric layer.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 illustrates an example operating environment for operating a microacoustic filter with a solidly mounted piezoelectric layer excitable to resonate in a Lame mode;WT Ref No. 1173-952Qualcomm Ref No. 2407752 3

[0009] Figure 2 illustrates an example wireless transceiver including at least one micro-acoustic filter with a piezoelectric layer configured to resonate in a Lame mode;

[0010] Figure 3-1 illustrates example components of a Lame mode micro-acoustic filter with a piezoelectric layer configured to resonate in a Lame mode;

[0011] Figure 3-2 illustrates example Euler angles that define an orientation of a piezoelectric layer of a micro-acoustic filter that operates in a Lame mode;

[0012] Figures 4A and 4B are illustrations of Lame mode oscillations in square and rectangular piezoelectric layers;

[0013] Figure 5 is a plan view of an interdigital transducer (IDT) structure to excite a solidly mounted piezoelectric layer in a Lame mode;

[0014] Figure 6A is a perspective view of one example of a micro-acoustic filter including a solidly mounted piezoelectric layer configured to operate in a Lame mode and including an IDT structure and a bottom electrode;

[0015] Figure 6B is a cross-sectional side view of the micro-acoustic filter in Figure 6A;

[0016] Figure 7 is a flowchart of a method of making the micro-acoustic filter in Figures 5, 6A, and 6B;

[0017] Figure 8 is a block diagram of an exemplary processor-based system that can include a solidly mounted piezoelectric layer excited to resonate in a Lame mode and includes an IDT structure and a bottom electrode; and

[0018] Figure 9 is a block diagram of an exemplary wireless communication device that includes radio-frequency (RF) components that can include a solidly mounted piezoelectric layer excited to resonate in a Lame mode, an IDT structure and a bottom electrode.DETAILED DESCRIPTION10019] With reference now to the drawing figures, several exemplary aspects of the present disclosure are described. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” should not necessarily be construed as preferred or advantageous over other aspects Aspects disclosed in the detailed description include solidly mounted Lame mode microacoustic resonators. Related methods of fabricating a solidly mounted Lame mode micro-WT Ref No. 1173-952Qualcomm Ref No. 2407752 4 acoustic resonator are also disclosed. As the frequencies of telecommunications (e.g., 4G, 5G, and 6G) increase over time, there is an increased need to develop micro-acoustic devices in which the efficiencies and frequencies of operation are not limited by the dimensions of their physical features, such as film thicknesses and electrode widths. An exemplary micro-acoustic resonator includes a piezoelectric layer that is excitable in a Lame mode by an interdigital transducer (IDT) structure and solidly mounted on an acoustic mirror and bottom electrode to provide increased effective electromechanical coupling. A resonant frequency depends on a width and spacing of the fingers of an IDT structure as well as a thickness of the piezoelectric layer. The bottom electrode may assist in containing the electric field that excites the piezoelectric layer to increase efficiency. An acoustic mirror, as employed in bulk acoustic wave devices, is employed to reduce acoustic losses.

[0020] To transmit or receive radio-frequency (RF) signals within a given frequency band, an electronic device may use filters to pass signals within the frequency band and suppress (e.g., attenuate) jammers or noise-having frequencies outside of the frequency band. Electroacoustic devices (e g., “acoustic filters”) can be used to filter high- frequency signals in many applications, such as those with frequencies that are greater than 100 megahertz (MHz). An acoustic filter is tuned to pass certain frequencies (e g., frequencies within its passband) and attenuate other frequencies (e.g., frequencies that are outside of its passband). In an acoustic resonator or an acoustic filter, an electrical signal having a time- varying voltage is applied to an electrode structure to create an electric field of varying intensity in a piezoelectric material. The piezoelectric material transforms the varying electric field into an acoustic wave. The acoustic wave induces an electric field in the piezoelectric material and the electrode structure detects the electric field and transforms or converts it to an electrical output signal.

[0021] The resonant frequencies of acoustic resonators are dependent on the dimensions of the acoustic resonator and / or electrode structure. Higher frequency signals have shorter wavelengths, which require the dimensions of the resonator and / or electrode features to be smaller. Accordingly, manufacturing technology limitations can make it challenging to design a micro-acoustic filter that can provide filtering for signals at higher frequencies, such as those used with Wi-Fi® at 2.4 gigahertz (GHz) frequencies, at 5 GHz frequencies, at frequencies greater than 5 GHz, at sub-6 GHz frequencies, at frequenciesWT Ref No. 1173-952Qualcomm Ref No. 2407752 5 between 6 and 10 GHz, and / or at frequencies greater than or equal to 10 GHz. In particular, it can be challenging to design a filter that is affordable and can achieve a target level of performance in terms of resonance quality factors, electromechanical coupling, power durability, insertion loss, and spurious-mode suppression.

[0022] To address these challenges, some micro-acoustic filters implement a Lame mode in the piezoelectric layer to realize a target level of performance in terms of electromechanical coupling, insertion loss, and quality factors at higher frequencies. IDT electrode dimensions may be feasible to manufacture even at higher frequencies. However, Lame mode resonators are typically implemented on thin films that are suspended on a frame. Anchor losses and spurious modes are characteristic disadvantages of membrane-type resonators. Separating thin films from a support substrate can also provide a manufacturing challenge as films become thinner. Careful selection of materials and geometry allows for fulfilling the boundary conditions required for a Lame mode resonator within a solid layer stack by decoupling the piezoelectric layer from the underlying substrate. This may be achieved by an appropriate decoupling interface consisting of an acoustic mirror, including a double layer or layers with different acoustic impedances.

[0023] Figure 1 illustrates an example environment 100 for operating a Lame -mode micro-acoustic filter with IDT electrodes separated from an outer (e.g., top) surface of a piezoelectric layer on a layer stack, including a substrate layer. In the environment 100, a computing device 102 communicates with a base station 104 through a wireless communication link 106 (wireless link 106). In this example, the computing device 102 depicted is a smartphone. However, the computing device 102 can be implemented as any suitable computing or electronic device, such as a modem, a cellular base station, a broadband router, an access point, a cellular phone, a gaming device, a navigation device, a media device, a laptop computer, a desktop computer, a tablet computer, a wearable computer, a server, a network-attached storage (NAS) device, a smart appliance or other internet of things (loT) device, a medical device, a vehicle-based communication system, a radar, a radio apparatus, and so forth. Use of a micro-acoustic filter is not limited to wireless communication as a micro-acoustic filter can be applied in any technological field where such filtering is useful.WT Ref No. 1173-952Qualcomm Ref No. 2407752 6

[0024] The base station 104 communicates with the computing device 102 via the wireless link 106, which can be implemented as any suitable type of wireless link Although depicted as a tower of a cellular network, the base station 104 can represent or be implemented as another device, such as a satellite, a server device, a terrestrial television broadcast tower, an access point, a peer-to-peer device, a mesh network node, and so forth. Therefore, the computing device 102 may communicate with the base station 104 or another device via a wireless connection.

[0025] The wireless link 106 can include a downlink of data or control information communicated from the base station 104 to the computing device 102, an uplink of other data or control information communicated from the computing device 102 to the base station 104, or both a downlink and an uplink The wireless link 106 can be implemented using any suitable communication protocol or standard, such as 2nd-generation (2G), 3 rd- generation (3G), 4th -gen eration (4G), 5th-generation (5G), or 6th-generation (6G) cellular; IEEE 802.11 (e.g., Wi-Fi®); IEEE 802.15 (e.g., Bluetooth®); IEEE 802.16 (e.g., WiMAX®); and so forth. In some implementations, the wireless link 106 may wirelessly provide power and the base station 104 or the computing device 102 may comprise a power source.

[0026] As shown, the computing device 102 includes an application processor 108 and a computer-readable storage medium 110 (CRM 110). The application processor 108 can include any type of processor, such as a multi-core processor that executes processorexecutable code stored by the CRM 110. The CRM 110 can include any suitable type of data storage media, such as volatile memory (e.g., random access memory (RAM)), nonvolatile memory (e g., Flash memory), optical media, magnetic media (e g., disk), and so forth. In the context of this disclosure, the CRM 110 is implemented to store instructions 1 12, data 1 14, and other information of the computing device 102 and thus does not include transitory propagating signals or carrier waves.|0027| The computing device 102 can also include input / output ports 116 (I / O ports 116) and a display 118. The I / O ports 116 enable data exchanges or interaction with other devices, networks, or users. The VO ports 116 can include serial ports (e g., universal serial bus (USB) ports), parallel ports, audio ports, infrared (IR) ports, user interface ports such as a touchscreen, and so forth. The display 118 presents graphics of the computing device 102, such as a user interface associated with an operating system,WT Ref No. 1173-952Qualcomm Ref No. 2407752 7 program, or application. Alternatively, or additionally, the display 118 can be implemented as a display port or virtual interface, through which the graphical content of the computing device 102 is presented.

[0028] A wireless transceiver 120 of the computing device 102 provides connectivity to respective networks and other electronic devices connected therewith. The wireless transceiver 120 can facilitate communication over any suitable type of wireless network, such as a wireless local area network (WLAN), peer-to-peer (P2P) network, mesh network, cellular network, ultra-wideband (UWB) network, wireless wide-area-network (WWAN), and / or wireless personal-area-network (WPAN). In the context of the example environment 100, the wireless transceiver 120 enables the computing device 102 to communicate with the base station 104 and the networks connected therewith. However, the wireless transceiver 120 can also enable the computing device 102 to communicate “directly” with other devices or networks.

[0029] The wireless transceiver 120 includes circuitry and logic for transmitting and receiving communication signals via an antenna 122. Components of the wireless transceiver 120 can include amplifiers, switches, mixers, analog-to-digital converters, filters, and so forth for conditioning the communication signals (e.g., for generating or processing signals). The wireless transceiver 120 can also include logic to perform in- phase / quadrature (I / Q) operations, such as synthesis, encoding, modulation, decoding, demodulation, and so forth. In some cases, components of the wireless transceiver 120 are implemented as separate transmitter and receiver entities. Additionally, or alternatively, the wireless transceiver 120 can be realized using multiple or different sections to implement respective transmitting and receiving operations (e g., separate transmit and receive chains). In general, the wireless transceiver 120 processes data and / or signals associated with communicating data of the computing device 102 over the antenna 122.|0030| In the example shown in Figure 1, the wireless transceiver 120 includes at least one micro-acoustic fdter 124 (e.g., an acoustic filter, a Lame mode acoustic-wave filter, or a membrane-type filter). In some implementations, the wireless transceiver 120 includes multiple micro-acoustic filters 124, which can be formed from micro-acoustic resonators arranged in series, in parallel, in a ladder structure, in a lattice structure, or some combination thereof The micro-acoustic filter 124 includes at least oneWT Ref No. 1173-952Qualcomm Ref No. 2407752 8 piezoelectric layer 126 disposed on an acoustic mirror 128 on a substrate 130 and excitable by an IDT structure 132 disposed on the piezoelectric layer 126 to resonate in a Lame mode. The microacoustic filter also includes a bottom electrode 136 between the acoustic mirror 128 and the piezoelectric layer 126.

[0031] Although the micro-acoustic filter 124 can be any type of micro-acoustic filter, the technique of employing the piezoelectric layer 126 solidly mounted on the bottom electrode 136 and acoustic mirror 128 and excitable in a Lame mode 134 can be particularly advantageous for reducing acoustic losses that would otherwise occur at an anchor of a thin-film membrane.

[0032] The piezoelectric layer 126 has a crystalline structure operative to excite the Lame mode 134 The Lame mode 134 forms an acoustic wave that causes a two- dimensional oscillation that activates lateral and thickness directions of the piezoelectric film as well as the elastic and piezoelectric moduli in two directions and increases the effective electromechanical coupling.

[0033] The IDT structure 132 is positioned on the piezoelectric layer 126, which is disposed on the acoustic mirror 128, including the substrate 130. In an exemplary aspect, the IDT structure 132 induces a time-varying electric field in the piezoelectric layer 126, causing the generation of acoustic waves in the Lame mode 134. The acoustic energy is reflected back to the piezoelectric layer 126 by the acoustic mirror 128, and the electric field is intensified in the piezoelectric layer 126 by the bottom electrode 136.

[0034] With these improvements, the micro-acoustic filter 124 can be designed to support frequency ranges above 2 GHz, including frequencies between approximately 2 and 20 GHz. For example, the micro-acoustic filter 124 can be designed to have a resonance frequency between approximately 4 and 18 GHz, between approximately 7.5 and 17 GHz, or equal to approximately 4, 5, 6, 10, 13, 15, 17, or 20 GHz. In general, the term “approximately” can mean that any of the frequencies can be within ± 10% of a specified value or less (e.g., within ± 5%, ± 3%, or ± 2% of a specified value). The microacoustic filter 124 is further described with respect to Figure 2.

[0035] Figure 2 illustrates an example of the wireless transceiver 120. In the depicted configuration, the wireless transceiver 120 includes a transmitter 202 and a receiver 204, which are respectively coupled to a first antenna 122-1 and a second antenna 122-2. In other implementations, the transmitter 202 and the receiver 204 can be connected to aWT Ref No. 1173-952Qualcomm Ref No. 2407752 9 same antenna through a duplexer (not shown). The transmitter 202 is shown to include at least one digital -to-analog converter 206 (DAC 206), at least one first mixer 208-1, at least one amplifier 210 (e.g., a power amplifier), and at least one first micro-acoustic filter 124-1. The receiver 204 includes at least one second micro-acoustic filter 124-2, at least one amplifier 212 (e.g., a low-noise amplifier), at least one second mixer 208-2, and at least one analog-to-digital converter 214 (ADC 214). The first mixer 208-1 and the second mixer 208-2 are coupled to a local oscillator 216. Although not explicitly shown, the DAC 206 of the transmitter 202 and the ADC 214 of the receiver 204 can be coupled to the application processor 108 (of Figure 1) or another processor associated with the wireless transceiver 120 (e.g., a modem).

[0036] In some implementations, the wireless transceiver 120 is implemented using multiple circuits (e.g., multiple integrated circuits), such as a transceiver circuit 236 and a radio-frequency front-end (RFFE) circuit 238. As such, the components that form the transmitter 202 and the receiver 204 are distributed across these circuits. As shown in Figure 2, the transceiver circuit 236 includes the DAC 206 of the transmitter 202, the mixer 208-1 of the transmitter 202, the mixer 208-2 of the receiver 204, and the ADC 214 of the receiver 204. In other implementations, the DAC 206 and the ADC 214 can be implemented on another separate circuit that includes the application processor 108 or the modem. The RFFE circuit 238 includes the amplifier 210 of the transmitter 202, the micro-acoustic filter 124-1 of the transmitter 202, the micro-acoustic filter 124-2 of the receiver 204, and the amplifier 212 of the receiver 204.

[0037] During transmission, the transmitter 202 generates a radio-frequency transmit signal 218, which is transmitted using the antenna 122-1. To generate the radio-frequency transmit signal 218, the DAC 206 provides a pre-upconversion transmit signal 220 to the first mixer 208-1 . The pre-upconversion transmit signal 220 can be a baseband signal or an intermediate-frequency signal. The first mixer 208-1 upconverts the pre-upconversion transmit signal 220 using a local oscillator (LO) signal 222 provided by the local oscillator 216. The first mixer 208-1 generates an upconverted signal, which is referred to as a prefilter transmit signal 224. The pre-filter transmit signal 224 can be a radio-frequency signal and include some noise or unwanted frequencies, such as a harmonic frequency. The amplifier 210 amplifies the pre-filter transmit signal 224 and passes the amplified pre-filter transmit signal 224 to the first micro-acoustic filter 124-1 .WT Ref No. 1173-952Qualcomm Ref No. 2407752 10

[0038] The first micro-acoustic filter 124-1 filters the amplified pre-filter transmit signal 224 to generate a filtered transmit signal 226. As part of the filtering process, the first micro-acoustic filter 124-1 attenuates the noise or unwanted frequencies within the pre-filter transmit signal 224. The transmitter 202 provides the filtered transmit signal 226 to the antenna 122-1 for transmission. The transmitted filtered transmit signal 226 is represented by the radio-frequency transmit signal 218.

[0039] During reception, the antenna 122-2 receives a radio-frequency receive signal 228 and passes the radio-frequency receive signal 228 to the receiver 204. The second micro-acoustic filter 124-2 accepts the received radio-frequency receive signal 228, which is represented by a pre-filter receive signal 230. The second micro-acoustic filter 124-2 filters any noise or unwanted frequencies within the pre-filter receive signal 230 to generate a filtered receive signal 232.

[0040] The amplifier 212 of the receiver 204 amplifies the filtered receive signal 232 and passes the amplified filtered receive signal 232 to the second mixer 208-2. The second mixer 208-2 downconverts the amplified filtered receive signal 232 using the LO signal 222 to generate the downconverted receive signal 234. The ADC 214 converts the downconverted receive signal 234 into a digital signal, which can be processed by the application processor 108 or another processor associated with the wireless transceiver 120 (e.g., the modem).

[0041] Figure 2 illustrates one example configuration of the wireless transceiver 120. Other configurations of the wireless transceiver 120 can support multiple frequency bands and share an antenna 122 across multiple transceivers. One of ordinary skill in the art can appreciate the variety of other configurations for which micro-acoustic filters 124 may be included. For example, the micro-acoustic filters 124 can be integrated within duplexers or diplexers of the wireless transceiver 120 Example implementations of the microacoustic filter 124-1 or 124-2 are further described with respect to Figure 3-1.100421 Figure 3-1 illustrates example components of the micro-acoustic filter 124. In the depicted configuration, the micro-acoustic filter 124 includes the piezoelectric layer 126 and the IDT 132. In example implementations, the piezoelectric layer 126 can be implemented using a variety of different materials that exhibit piezoelectric properties (e g., can transfer mechanical energy into electrical energy or electrical energy into mechanical energy). Example types of material include lithium niobate (LiNbOs), lithiumWT Ref No. 1173-952Qualcomm Ref No. 2407752 11 tantalate (LiTaCh), or some combination thereof. Generally, the material that forms the piezoelectric layer 126 may have a crystalline structure. This crystalline structure is defined by an ordered arrangement of particles (e.g., atoms, ions, or molecules). The orientation of the crystalline structure of the piezoelectric layer 126 can be defined by Euler angles lambda ( ), mu (p), and theta (0).

[0043] In some aspects, the material and crystalline structure of the piezoelectric layer 126 is selected such that the Lame mode 134 can be excited within the piezoelectric layer 126. As an example, in one-hundred fifty-five degree (155°) rotated Y-cut plates of lithium niobate (LiNCh), the Lame mode 134 can be excited.

[0044] Consider an example in which the piezoelectric layer 126 is formed using lithium niobate. In a first example implementation, the lithium niobate material is cut such that a value of the Euler angle mu (p) is approximately 155° and values of the Euler angles lambda (X) and theta (0) are approximately 180° and 0°, respectively. In general, the term “approximately” can mean that any of the angles can be within ± 10% of a specified value or less (e.g., within ± 5%, ± 3%, or ± 2% of a specified value).

[0045] For the Lame mode 134, a resonance frequency of the micro-acoustic filter 124 is dependent on both a thickness of the piezoelectric layer 126 as well as the dimensions of the IDT structure 132

[0046] The IDT structure 132 comprises an electrically conductive material, such as metal, and can include one or more layers. The one or more layers can include one or more electrically conductive layers and can optionally include one or more adhesion layers. As an example, the electrically conductive layers can be composed of aluminum (Al), copper (Cu), silver (Ag), gold (Au), tungsten (W), silicon (Si), or some combination or doped version thereof. The adhesion layers can be composed of chromium (Cr), titanium (Ti), molybdenum (Mo), or some combination thereof.

[0047] The IDT structure 132 can include at least two comb-shaped electrodes 304-1 and 304-2. Each comb-shaped electrode 304-1 and 304-2 includes a busbar (e.g., a conductive segment or rail) and multiple fingers (e.g., electrode fingers). Examples of the IDT structure 132 are further described with respect to Figures 5 and 6A. As shown in Figure 5, the IDT structure 132 can also include two or more acoustic reflectors. In example implementation, the IDT structure 132 may be arranged between two reflectors.WT Ref No. 1173-952Qualcomm Ref No. 2407752 12

[0048] The micro-acoustic filter 124 also includes a substrate stack 310 (also referred to as layer stack 310), which represents an example implementation of the substrate 130 of Figure 1. The bottom electrode 136 may be disposed directly on or indirectly on (e.g., without or with an intervening layer(s)) the layer stack 310. The layer stack 310 includes an acoustic mirror 128 on a substrate layer 316. The acoustic mirror 128 may also be referred to herein as a Bragg mirror 128. The acoustic mirror 128 includes alternating higher acoustic impedance layers 312 and lower acoustic impedance layers 314. The substrate layer 316 is composed of non-conducting material that provides isolation. Example materials of the substrate layer 316 include silicon (Si), silicon dioxide (SiCh), silicon carbide (SiC), sapphire, glass, or some combination or doped version thereof. In some implementations, the substrate layer 316 is composed of multiple layers. The multiple layers can be formed using the same material or different materials.

[0049] Figure 3-2 illustrates example Euler angles that define an orientation of the piezoelectric layer 126 relative to a crystalline structure of the material that forms the piezoelectric layer 126. In this example, the material that forms the piezoelectric layer 126 includes lithium niobate and / or lithium tantalate. A first crystalline (X’) axis 326, a second crystalline (Y’) axis 328, and a third crystalline (Z’) axis 330 are fixed along the crystallographic axes of a lithium niobate crystal. A first rotation 324-1 is applied to rotate the first crystalline X’ axis 326 and the second crystalline Y’ axis 328 about the third crystalline Z’ axis 330. In particular, the first rotation 324-1 rotates the first crystalline X’ axis 326 in a direction of the second crystalline Y’ axis 328. The angle associated with the first rotation 324-1 characterizes one of the Euler angles, which is represented by Euler angle lambda ( ) 332. The resulting rotated axes are represented by a new set of axes: an X” axis 334, a Y” axis 336, and a Z” axis 338. As shown in Figure 3-2, the third crystalline Z’ axis 330 remains unchanged by the first rotation 324- 1 such that the third crystalline Z’ axis 330 is equal to the Z” axis 338.|0050| In a second rotation 324-2, the Y” axis 336 and the Z” axis 338 are rotated about the X” axis 334 by another Euler angle, which is represented by Euler angle mu (p) 340. In this case, the Y” axis 336 is rotated in the direction of the Z” axis 338. The resulting rotated axes are represented by a new set of axes: an X’” axis 342, a Y’” axis 344, and a Z’” axis 346. As shown in Figure 3-2, the X” axis 334 remainsWT Ref No. 1173-952Qualcomm Ref No. 2407752 13 unchanged by the second rotation 324-2 such that the X” axis 334 is equal to the X’” axis 342.

[0051] In a third rotation 324-3, the X’” axis 342 and the Y’” 344 axis are rotated about the Z’” axis 346 by an additional Euler angle, which is represented by Euler angle theta (0) 348. In this case, the X’” axis 342 is rotated in the direction of the Y’” axis 344. The resulting rotated axes are represented by a first filter (X) axis 350, a second filter (Y) axis 352, and a third filter (Z) axis 354, which respectively correspond to the X-axis, the Y-axis, and the Z-axis of Figure 4A. As shown in Figure 3-2, the Z’” axis 346 remains unchanged by the third rotation 324-3 such that the Z” ’ axis 346 is equal to the third filter Z axis 354. The micro-acoustic filter 124 is further described with respect to Figure 4A.

[0052] Figure 4A is an illustration of Lame mode oscillations in a square piezoelectric layer 400A. The piezoelectric layer 400A includes sides A, B, C, and D having equal lengths L, with side A and side B being opposite to each other and extending in a first, X- axis direction and sides C and D being opposite to each other and extending in a second, Y-axis direction. In a Lame mode oscillation, at one extreme of a range of oscillation, the sides A and B extend outward from the center 402A, as shown by lines A’ and B’, the sides C and D draw inwards toward the center 402, as shown by lines C’ and D'. In an opposite extreme, the situations are reversed, with sides C and D extending outward while the sides A and B draw inward toward the center 402A (not shown).

[0053] As shown in Figure 4B, the Lame mode oscillations are also possible in the piezoelectric layer 400B, having sides E, F, G, and H, where the opposite sides E and F have a length L and the opposite sides G and H have a length 2xL. Thus, the length of sides G and H is an integer multiple of the sides E and F Here, a first region 404A of the piezoelectric layer 400B oscillates in the same manner and to the same extreme as in Figure 4A while a second region 404B of the piezoelectric layer 400B is at an opposite extreme in the oscillation range. Both the first region 404A and the second region 404B oscillate in the manner of the piezoelectric layer 400A in Figure 4A but in a complementary manner. It should be understood that there are also changes in thickness (e.g., in the third, Z-axis direction) (not shown) of the piezoelectric layers 400A and 400B corresponding to the changes in the X-axis and Y-axis directions. The X, Y, and Z axes in Figure 4A are orthogonal to each other.WT Ref No. 1173-952Qualcomm Ref No. 2407752 14

[0054] Figure 5 is a plan view of an IDT structure 500 on a surface 502 of a piezoelectric layer 504 that is configured to be excited in a Lame mode The IDT structure 500 includes a first electrode 506A, which is a comb-like structure, including a first spine 508A and first fingers 510A coupled to the first spine 508A. The IDT structure 500 also includes a second electrode 506B, which is also comb-like in shape and includes a second spine 508B and second fingers 510B coupled to the second spine 508B. As shown, the fingers 510A and 510B extend in a first, Y-axis direction. The first fingers 510A and the second fingers 510B a disposed alternately in a second, X-axis direction. A signal voltage VSIG may be applied to the first spine 510 and a reference (e.g., ground) voltage VGND may be applied to the second spine 508B. The signal voltage VSIG between the first fingers 510A and the second fingers 510B creates electric fields in the piezoelectric layer 504. In response to the electric fields, the piezoelectric layer 504 expands and contracts to create the oscillations in the Lame mode. This example includes acoustic reflectors 512A and 512B provided on the surface 502 to reflect surface waves propagating in the X-axis direction in the piezoelectric layer 504 back toward the IDT structure 500, to reduce acoustic losses.

[0055] Figure 6A is a perspective view of one example of a micro-acoustic resonator 600 configured to operate in a Lame mode and including an IDT structure 602 including a first electrode 604A having first fingers 606A and a second electrode 604B having second fingers 606B. The first fingers 606A and the second fingers 606B extend in a first, X-axis direction on a first side SI of a piezoelectric layer 608 and alternate in a second, Y-axis direction. A second side S2 of the piezoelectric layer 608 is disposed on a layer stack 610 that includes an acoustic mirror 612 on a substrate 614. The microacoustic resonator 600 also includes a bottom electrode 616 disposed between the piezoelectric layer 608 and the acoustic mirror 612. The first electrode 604A is configured to couple to a first voltage, and the second electrode 604B is configured to couple to a second voltage. The first voltage may be a signal voltage VSIG and the second voltage may be a reference (e.g., ground voltage) VGND as discussed with regard to Figure 5. In some examples, the first electrode 604A may be coupled to the reference voltage VGND and the second electrode 604B may be coupled to the signal voltage VSIG. In this regard, the piezoelectric layer 608 is configured to be excited or excitable by the IDT structure 602 to oscillate in a Lame mode as described above.WT Ref No. 1173-952Qualcomm Ref No. 2407752 15

[0056] The IDT structure 602 may be formed of any appropriate conductive material(s), such as metals (e.g., aluminum (Al), copper (Cu), titanium (Ti), platinum (Pt), molybdenum (Mo), and / or alloys of such metals or other metals). The bottom electrode 616 may be formed of molybdenum (Mo) or any appropriate metal, which may be the same or different than the IDT structure 602. In some examples, the IDT structure 602 may comprise a metal layer excluding molybdenum. Unlike the IDT structure 602, however, the bottom electrode 616 is not patterned to form electrodes. Rather, the bottom electrode 616 is a continuous metal layer between the IDT structure 602 and the acoustic mirror 612. In some examples, the bottom electrode 616 may extend under the piezoelectric layer only in an area of the IDT structure 602, as indicated by optional boundaries 618 A and 618B. In other examples, there may be acoustic reflectors corresponding to the acoustic reflectors 512A and 512B in Figure 5 (but not shown here) disposed in areas 626A and 626B at opposite ends of the piezoelectric layer 608, on either side of the IDT structure 602. In such examples, in addition to the bottom electrode 616 extending continuously (e.g., unpattemed) between the IDT structure 602 and the acoustic mirror 612, the bottom electrode 616 also extends continuously between the acoustic reflectors and the acoustic mirror 612. In addition, the bottom electrode 616 may be disconnected from the signal voltage VSIG and from the reference voltage VGND. In some examples, the bottom electrode 616 may be electrically floating with respect to the IDT structure 602.

[0057] The microacoustic resonator 600 may include a first electrical insulating layer 620 between the piezoelectric layer 608 and the bottom electrode 616 and may include a second electrical insulating layer 622 between the piezoelectric layer 608 and the acoustic mirror 612. The first and second electrical insulating layers 620 and 622 may be any appropriate insulating material such as AIN.

[0058] The acoustic mirror 612 disposed between the piezoelectric layer 608 and the substrate 614 may be referred to herein as a Bragg mirror comprising alternating layers of a first material having a low acoustic impedance and a second material having a high acoustic impedance material. The low acoustic impedance layers of an acoustic mirror 612 may be, but are not limited to, silicon dioxide (SiO2) or silicon oxycarbide (SiOC), and the high acoustic impedance layers of the acoustic mirror 612 may be, but are not limited to, tungsten (W), aluminum nitride (AIN), silicon carbide (SiC), hafnium oxideWT Ref No. 1173-952Qualcomm Ref No. 2407752 16(HfO2) and / diamond (C). Optionally, an extra low Z or high Z may be added, resulting in a stack of n+’A double layers. Although the acoustic mirror 612 in Figure 6 includes four (4) layers 624(l)-624(4) in this example, the acoustic mirror 612 may include as few as two (2) layers and up to six (6) or more.

[0059] The piezoelectric layer 608 may be a film and may comprise piezoelectric materials such as zinc oxide (ZnO), aluminum nitride (AIN), doped AIN materials (e g., scandium-doped aluminum nitride (AlScN, AlxScl-xN)), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), or other piezoelectric materials.

[0060] Figure 6B is a cross-sectional side view of the microacoustic resonator 600 in Figure 6A and is provided to illustrate a distance L between a first finger 606A and a second finger 606B is half or approximately half of a center-to-center distance P between respective first fingers 606A. The distance P may also correspond to a wavelength of resonance of the microacoustic resonator 600. However, such wavelength may also be dependent on a thickness TOOK of the piezoelectric layer 608. The thickness Tsos of the piezoelectric layer 608 may be in a range from fifteen percent to 80 percent (15%-80%) of the distance P. A height Hr, nt, of the first fingers 606A and the second fingers 606B may be in a range of five percent to fifteen percent (5%-15%) of the distance P.

[0061] The effective electromechanical coupling of the solidly mounted Lame mode resonator is lower than the coupling of a free-plate fundamental Lame mode resonator because of the elastic stresses between neighboring electrodes. This stress influence can be reduced by etching the piezoelectric layer between the electrodes. Thus, in some examples, the piezoelectric layer 608 may optionally be etched (reduced) between the first fingers 606A and the second fingers 606B to a level 628 having a second thickness T628 between the first fingers 606A and the second fingers 606B that is less than the first thickness Teos of the piezoelectric layer 608 under the first fingers 606A and the second fingers 606B.10062] Figure 7 is a flowchart of a method 700 of making the micro-acoustic filter in Figures 4A and 4B. The method includes forming an acoustic mirror 612 on a substrate 614 (block 702) and forming a bottom electrode 616 on the acoustic mirror 612 (block 704). The method includes forming a piezoelectric layer 608 on the bottom electrode 616, the piezoelectric layer 608 having a crystalline structure operative to excite a Lame mode (block 706). The method 700 further includes forming an IDT structure 602WT Ref No. 1173-952Qualcomm Ref No. 2407752 17 comprising a first electrode 606A and a second electrode 606B disposed on the piezoelectric layer 608 (block 708).

[0063] Lame mode micro-acoustic resonators, including piezoelectric layers solidly mounted on a bottom electrode on an acoustic mirror with IDT structures on the piezoelectric layers providing effective electromechanical coupling to reduce energy losses, may be included in processor-based devices. Examples of such processor-based devices, without limitation, include a set top box, an entertainment unit, a navigation device, a communications device, a fixed location data unit, a mobile location data unit, a global positioning system (GPS) device, a mobile phone, a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a tablet, a phablet, a server, a computer, a portable computer, a mobile computing device, laptop computer, a wearable computing device (e.g., a smart watch, a health or fitness tracker, eyewear, etc.), a desktop computer, a personal digital assistant (PDA), a monitor, a computer monitor, a television, a tuner, a radio, a satellite radio, a music player, a digital music player, a portable music player, a digital video player, a video player, a digital video disc (DVD) player, a portable digital video player, an automobile, a vehicle component, an avionics system, a drone, and a multicopter.

[0064] Figure 8 illustrates an exemplary wireless communications device 800 that includes radio-frequency (RF) components formed from one or more ICs 802, wherein any of the ICs 802 may include a micro-acoustic resonator operative in a Lame mode and a piezoelectric layer solidly mounted on a bottom electrode disposed on an acoustic mirror and an IDT structure on the piezoelectric layer providing effective electromechanical coupling to reduce energy losses, as shown in Figures 5, 6A, and 6B. The wireless communications device 800 may include or be provided in any of the above-referenced devices as examples. As shown in Figure 8, the wireless communications device 800 includes a transceiver 804 and a data processor 806. The data processor 806 may include a memory to store data and program codes. The transceiver 804 includes a transmitter 808 and a receiver 810 that supports bi-directional communications. In general, the wireless communications device 800 may include any number of transmitters 808 and / or receivers 810 for any number of communication systems and frequency bands. All or a portion of the transceiver 804 may be implemented on one or more analog ICs, RF ICs (RFTCs), mixed-signal ICs, etc.WT Ref No. 1173-952Qualcomm Ref No. 2407752 18

[0065] The transmiter 808 or the receiver 810 may be implemented with a superheterodyne architecture or a direct-conversion architecture. In the super-heterodyne architecture, a signal is frequency-converted between RF and baseband in multiple stages, for example, from RF to an intermediate frequency (IF) in one stage and then from IF to baseband in another stage for the receiver 810. In the direct-conversion architecture, a signal is frequency-converted between RF and baseband in one stage. The superheterodyne and direct-conversion architectures may use different circuit blocks and / or have different requirements. In the wireless communications device 800 in Figure 8, the transmitter 808 and the receiver 810 are implemented with the direct-conversion architecture.

[0066] In the transmit path, the data processor 806 processes data to be transmitted and provides I and Q analog output signals to the transmitter 808. In the exemplary wireless communications device 800, the data processor 806 includes digital-to-analog converters (DACs) 812(1), 812(2) for converting digital signals generated by the data processor 806 into the I and Q analog output signals (e.g., I and Q output currents) for further processing.

[0067] Within the transmiter 808, lowpass filters 814(1), 814(2) filter the I and Q analog output signals, respectively, to remove undesired signals caused by the prior digital-to-analog conversion. Amplifiers (AMPs) 816(1), 816(2) amplify the signals from the lowpass filters 814(1), 814(2), respectively, and provide 1 and Q baseband signals. An upconverter 818 upconverts the I and Q baseband signals with I and Q transmit (TX) local oscillator (LO) signals through mixers 820(1), 820(2) from a TX LO signal generator 822 to provide an upconverted signal 824. A filter 826 filters the upconverted signal 824 to remove undesired signals caused by the frequency up-conversion as well as noise in a receive frequency band A power amplifier (PA) 828 amplifies the upconverted signal 824 from the filter 826 to obtain the desired output power level and provides a transmit RF signal. The transmit RF signal is filtered by a transmit filter 854 before being routed through a duplexer or switch 830 and transmitted via an antenna 832. The transmit filter 854 may be a micro-acoustic filter including a micro-acoustic resonator operative in a Lame mode and including a piezoelectric layer solidly mounted on a botom electrode disposed on an acoustic mirror and an IDT structure on the piezoelectric layer providing effective electromechanical coupling to reduce energy losses.WT Ref No. 1173-952Qualcomm Ref No. 2407752 19

[0068] In the receive path, the antenna 832 receives signals transmitted by base stations and provides a received RF signal, which is routed through the duplexer or switch 830 and receiver filter 852 before being provided to a low noise amplifier (LNA) 834. The receive filter 852 may be a micro-acoustic filter including a micro-acoustic resonator operative in a Lame mode and including a piezoelectric layer solidly mounted on a bottom electrode disposed on an acoustic mirror and an IDT structure on the piezoelectric layer providing effective electromechanical coupling to reduce energy losses, as shown in Figures 5, 6A, and 6B, and may be included in or separate from the duplexer or switch 830. The duplexer or switch 830 is designed to operate with a specific receive (RX)-to- TX duplexer frequency separation, such that RX signals are isolated from TX signals. The received RF signal is amplified by the LNA 834 and filtered by a filter 836 to obtain a desired RF input signal. Down-conversion mixers 838(1), 838(2) mix the output of the filter 836 with T and Q RX LO signals (i.e , LO T and LO_Q) from an RX LO signal generator 840 to generate I and Q baseband signals. The I and Q baseband signals are amplified by AMPs 842(1), 842(2) and further filtered by lowpass filters 844(1), 844(2) to obtain I and Q analog input signals, which are provided to the data processor 806. In this example, the data processor 806 includes analog-to-digital converters (ADCs) 846(1), 846(2) for converting the analog input signals into digital signals to be further processed by the data processor 806.

[0069] In the wireless communications device 800 of Figure 8, the TX LO signal generator 822 generates the I and Q TX LO signals used for frequency up-conversion, while the RX LO signal generator 840 generates the I and Q RX LO signals used for frequency down-conversion. Each LO signal is a periodic signal with a particular fundamental frequency. A TX phase-locked loop (PLL) circuit 848 receives timing information from the data processor 806 and generates a control signal used to adjust the frequency and / or phase of the TX LO signals from the TX LO signal generator 822. Similarly, an RX PLL circuit 850 receives timing information from the data processor 806 and generates a control signal used to adjust the frequency and / or phase of the RX LO signals from the RX LO signal generator 840.

[0070] In this regard, Figure 9 illustrates an example of a processor-based system 900 that can include a micro-acoustic filter including a micro-acoustic resonator operative in a Lame mode and a piezoelectric layer solidly mounted on a bottom electrode disposedWT Ref No. 1173-952Qualcomm Ref No. 2407752 20 on an acoustic mirror and an IDT structure on the piezoelectric layer providing effective electromechanical coupling to reduce energy losses as shown in Figures 5, 6A, and 6B. The processor-based system 900 includes a central processing unit (CPU) 908 that includes one or more processors 910, which may also be referred to as CPU cores or processor cores. The CPU 908 may have cache memory 912 coupled to the CPU 908 for rapid access to temporarily stored data. The CPU 908 is coupled to a system bus 914 and can intercouple master and slave devices included in the processor-based system 900. As is well known, the CPU 908 communicates with these other devices by exchanging address, control, and data information over the system bus 914. For example, the CPU 908 can communicate bus transaction requests to a memory controller 916, as an example of a slave device. Although not illustrated in Figure 9, multiple system buses 914 could be provided, wherein each system bus 914 constitutes a different fabric.

[0071] Other master and slave devices can be connected to the system bus 914. As illustrated in Figure 9, these devices can include a memory system 920 that includes the memory controller 916 and a memory array(s) 918, one or more input devices 922, one or more output devices 924, one or more network interface devices 926, and one or more display controllers 928, as examples. The input device(s) 922 can include any type of input device, including, but not limited to, input keys, switches, voice processors, etc The output device(s) 924 can include any type of output device, including, but not limited to, audio, video, other visual indicators, etc. The network interface device(s) 926 can be any device configured to allow an exchange of data to and from a network 930. The network 930 can be any type of network, including, but not limited to, a wired or wireless network, a private or public network, a local area network (LAN), a wireless local area network (WLAN), a wide area network (WAN), a BLUETOOTH™ network, and the Internet The network interface device(s) 926 can be configured to support any type of communications protocol desired.10072| The CPU 908 may also be configured to access the display controller(s) 928 over the system bus 914 to control information sent to one or more displays 932. The display controller) s) 928 sends information to the display(s) 932 to be displayed via one or more video processor) s) 934, which processes the information to be displayed into a format suitable for the display(s) 932. The display(s) 932 can include any type of display,WT Ref No. 1173-952Qualcomm Ref No. 2407752 21 including, but not limited to, a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, a light emitting diode (LED) display, etc.

[0073] Those of skill in the art will further appreciate that the various illustrative logical blocks, modules, circuits, and algorithms described in connection with the aspects disclosed herein may be implemented as electronic hardware, instructions stored in memory or in another computer-readable medium wherein any such instructions are executed by a processor or other processing device, or combinations of both. The devices and components described herein may be employed in any circuit, hardware component, integrated circuit (IC), or IC chip, as examples. Memory disclosed herein may be any type and size of memory and may be configured to store any type of information desired. To clearly illustrate this interchangeability, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. How such functionality is implemented depends upon the particular application, design choices, and / or design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

[0074] The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0075] The aspects disclosed herein may be embodied in hardware and in instructions that are stored in hardware and may reside, for example, in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk,WT Ref No. 1173-952Qualcomm Ref No. 2407752 22 a removable disk, a CD-ROM, or any other form of computer readable medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from and write information to the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a remote station. In the alternative, the processor and the storage medium may reside as discrete components in a remote station, base station, or server.

[0076] It is also noted that the operational steps described in any of the exemplary aspects herein are described to provide examples and discussion. The operations described may be performed in numerous different sequences other than the illustrated sequences. Furthermore, operations described in a single operational step may actually be performed in a number of different steps. Additionally, one or more operational steps discussed in the exemplary aspects may be combined It is to be understood that the operational steps illustrated in the flowchart diagrams may be subject to numerous different modifications which will be readily apparent to one of skill in the art. Those of skill in the art will also understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0077] It should be understood that the terms “first,” “second,” “third,” etc., where used herein, are relative terms that may be used to distinguish between similarly named elements and are not meant to limit or imply a strict orientation and / or order unless otherwise specified It should also be understood that that the terms “top,” “upper,” “above,” and “bottom,” “lower,” “below,” where used herein, are relative terms and are not meant to limit or imply a strict orientation. A “top” or “upper” or “above” referenced element does not always need to be oriented to be above a “bottom,” or “lower,” or “below” referenced element with respect to ground, and vice versa. An element referenced as “top,” “upper,” “above,” or “bottom,” “lower,” “below,” may be on top or bottom relative to that example only and the particular illustrated example. An element referenced as “top” or “upper” or “above” “bottom,” “lower,” “below,” another elementWT Ref No. 1173-952Qualcomm Ref No. 2407752 23 does not have to be with respect to ground, and vice versa. An element referenced as “top” or “upper” or “above” may be above or below such other referenced element, relative to that example only and the particular illustrated example. For example, if a particular object that is discussed as at “top,” or “upper” or “above” another object, and such particular object is flipped 180 degrees, then such particular object would then be oriented as at “bottom,” or “lower” or “below” such other object.

[0078] Further, an object being “adjacent” as discussed herein relates to an object being beside or next to another stated object. Adjacent objects may not be directly physically coupled to each other. An object can be directly adjacent to another object which means that such objects are directly beside or next to the other object without another object or layer being intervening or disposed between the directly adjacent objects. An object can be indirectly or non-directly adjacent to another object which means that such objects are not directly beside or directly next to each other, but there is an intervening object or layer disposed between the non-directly adjacent objects.

[0079] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0080] Implementation examples are described in the following numbered clauses:1. A micro-acoustic filter comprising: a substrate; an acoustic mirror disposed on the substrate; a piezoelectric layer having a crystalline structure operative to excite a Lame mode; a bottom electrode disposed between the acoustic mirror and a first side of the piezoelectric layer; and an interdigital transducer (IDT) structure comprising a first electrode and a second electrode and disposed on the piezoelectric layer.WT Ref No. 1173-952Qualcomm Ref No. 2407752 242. The micro-acoustic filter of clause 1, wherein: the first electrode comprises a plurality of first fingers extending in a first direction, the second electrode comprises a plurality of second fingers extending in the first direction, and the plurality of first fingers and the plurality of second fingers alternately disposed in a second direction.3. The micro-acoustic filter of clause 2, the IDT structure configured to provide an electrical signal to the second side of the piezoelectric layer based on a first voltage of the plurality of first fingers and a second voltage of the plurality of second fingers.4. The micro-acoustic filter of clause 3, wherein the bottom electrode is electrically disconnected from the first voltage and the second voltage.5. The micro-acoustic filter of any of clause 2 to clause 4, further comprising: a first acoustic reflector disposed on the second side of the piezoelectric layer, and a second acoustic reflector disposed on the second side of the piezoelectric layer; wherein the IDT structure is disposed between the first acoustic reflector and the second acoustic reflector in the second direction.6. The micro-acoustic filter of clause 5, the bottom electrode comprising a continuous metal layer between the IDT structure and the acoustic mirror.7. The micro-acoustic filter of clause 6, the continuous metal layer of the bottom electrode extending between the first acoustic reflector and the acoustic mirror and between the second acoustic reflector and the acoustic mirror.8. The micro-acoustic filter of any of clause 1 to clause 7, further comprising: a first electrical insulating layer between the piezoelectric layer and the bottom electrode.WT Ref No. 1173-952Qualcomm Ref No. 2407752 259. The micro-acoustic filter of any of clause 1 to clause 8, further comprising: a second electrical insulating layer between the bottom electrode and the acoustic mirror.10. The micro-acoustic filter of any of clause 3 to clause 9, wherein: the bottom electrode comprises molybdenum (Mo).11. The micro-acoustic filter of any of clause 2 to clause 10, wherein a height of the plurality of first fingers and the plurality of second fingers in a third direction, orthogonal to the first direction and the second direction, is in a range of five percent to fifteen percent (5%- 15%) of a center-to-center distance in the second direction between the first fingers.12. The micro-acoustic filter of any of clause 1 to clause 1 1 , wherein the acoustic mirror comprises first layers of a first material having a lower acoustic impedance alternating with second layers of a second material having a higher acoustic impedance.13. The micro-acoustic filter of any of clause 1 to clause 12, wherein the piezoelectric layer comprises at least one of zinc oxide (ZnO), aluminum nitride (AIN), aluminum scandium nitride (AlScN or AlxSci-xN), lithium niobate (LiNbCh), and lithium tantalate (LiTaOs).14. The micro-acoustic filter of any of clause 2 to clause 13, wherein: the piezoelectric layer has a first thickness, in a third direction orthogonal to the first direction and the second direction, in areas on which the plurality of first fingers and the plurality of second fingers of the TOT structure are disposed; and the piezoelectric layer has a second thickness, less than the first thickness, in the third direction in areas between the plurality of first fingers and the plurality of second fingers in the second direction.WT Ref No. 1173-952Qualcomm Ref No. 2407752 2615. The micro-acoustic filter of any of clause 1 to clause 14 integrated into a device selected from the group consisting of: a set-top box; an entertainment unit; a navigation device, a communications device, a fixed location data unit; a mobile location data unit, a global positioning system (GPS) device; a mobile phone; a cellular phone; a smartphone; a session initiation protocol (SIP) phone; a tablet, a phablet, a server; a computer; a portable computer; a mobile computing device; a wearable computing device; a desktop computer; a personal digital assistant (PDA); a monitor; a computer monitor; a television; a tuner; a radio; a satellite radio; a music player; a digital music player; a portable music player; a digital video player; a video player; a digital video disc (DVD) player; a portable digital video player; an automobile; a vehicle component; an avionics system; a drone; and a multicopter.16. A method of fabricating a micro-acoustic filter, comprising: forming an acoustic mirror on a substrate; forming a bottom electrode on the acoustic mirror; forming a piezoelectric layer on the bottom electrode, the piezoelectric layer having a crystalline structure operative to excite a Lame mode; and forming an interdigital transducer (IDT) structure comprising a first electrode and a second electrode disposed on the piezoelectric layer.17. A wireless transceiver comprising: a plurality of micro-acoustic resonators, each microacoustic resonator of the plurality of micro-acoustic resonators comprising: a substrate; an acoustic mirror; a piezoelectric layer having a crystalline structure operative to excite a Lame mode; a bottom electrode layer disposed between the acoustic mirror and a first side of the piezoelectric layer; and an interdigital transducer (IDT) structure comprising a first electrode and a second electrode and disposed on a second side of the piezoelectric layerWT Ref No. 1173-952

Claims

Qualcomm Ref No. 2407752 27What is claimed is:

1. A micro-acoustic filter comprising: a substrate; an acoustic mirror disposed on the substrate; a piezoelectric layer having a crystalline structure operative to excite a Lame mode, a bottom electrode disposed between the acoustic mirror and a first side of the piezoelectric layer; and an interdigital transducer (IDT) structure comprising a first electrode and a second electrode and disposed on the piezoelectric layer.

2. The micro-acoustic filter of claim 1, wherein: the first electrode comprises a plurality of first fingers extending in a first direction; the second electrode comprises a plurality of second fingers extending in the first direction; and the plurality of first fingers and the plurality of second fingers alternately disposed in a second direction.

3. The micro-acoustic filter of claim 2, the IDT structure configured to provide an electrical signal to the second side of the piezoelectric layer based on a first voltage of the plurality of first fingers and a second voltage of the plurality of second fingers.

4. The micro-acoustic filter of claim 3, wherein the bottom electrode is electrically disconnected from the first voltage and the second voltage.

5. The micro-acoustic filter of claim 2, further comprising: a first acoustic reflector disposed on the second side of the piezoelectric layer; and a second acoustic reflector disposed on the second side of the piezoelectric layer; wherein the IDT structure is disposed between the first acoustic reflector and the second acoustic reflector in the second directionWT Ref. No. 1173-952Qualcomm Ref No. 2407752 286. The micro-acoustic filter of claim 5, the bottom electrode comprising a continuous metal layer between the IDT structure and the acoustic mirror.

7. The micro-acoustic filter of claim 6, the continuous metal layer of the bottom electrode extending between the first acoustic reflector and the acoustic mirror and between the second acoustic reflector and the acoustic mirror.

8. The micro-acoustic filter of claim 1, further comprising: a first electrical insulating layer between the piezoelectric layer and the bottom electrode.

9. The micro-acoustic filter of claim 1, further comprising: a second electrical insulating layer between the bottom electrode and the acoustic mirror.

10. The micro-acoustic filter of claim 3, wherein: the bottom electrode comprises molybdenum (Mo).

11. The micro-acoustic filter of claim 2, wherein a height of the plurality of first fingers and the plurality of second fingers in a third direction, orthogonal to the first direction and the second direction, is in a range of five percent to fifteen percent (5%- 15%) of a center-to-center distance in the second direction between the first fingers.

12. The micro-acoustic filter of claim 1, wherein the acoustic mirror comprises first layers of a first material having a lower acoustic impedance alternating with second layers of a second material having a higher acoustic impedance.

13. The micro-acoustic filter of claim 1, wherein the piezoelectric layer comprises at least one of zinc oxide (ZnO), aluminum nitride (AIN), aluminum scandium nitride (AlScN or AlxSci-xN), lithium niobate (LiNbO ), and lithium tantalate (I.iTaO ;).WT Ref No. 1173-952Qualcomm Ref No. 2407752 2914. The micro-acoustic filter of claim 2, wherein: the piezoelectric layer has a first thickness, in a third direction orthogonal to the first direction and the second direction, in areas on which the plurality of first fingers and the plurality of second fingers of the IDT structure are disposed; and the piezoelectric layer has a second thickness, less than the first thickness, in the third direction in areas between the plurality of first fingers and the plurality of second fingers in the second direction.

15. The micro-acoustic filter of claim 1 integrated into a device selected from the group consisting of: a set-top box; an entertainment unit; a navigation device; a communications device; a fixed location data unit; a mobile location data unit; a global positioning system (GPS) device; a mobile phone; a cellular phone; a smartphone; a session initiation protocol (SIP) phone; a tablet; a phablet; a server; a computer; a portable computer; a mobile computing device; a wearable computing device; a desktop computer; a personal digital assistant (PDA); a monitor; a computer monitor; a television; a tuner; a radio; a satellite radio; a music player; a digital music player; a portable music player; a digital video player; a video player; a digital video disc (DVD) player; a portable digital video player, an automobile; a vehicle component; an avionics system, a drone; and a multicopter.

16. A method of fabricating a micro-acoustic filter, comprising: forming an acoustic mirror on a substrate; forming a bottom electrode on the acoustic mirror; forming a piezoelectric layer on the bottom electrode, the piezoelectric layer having a crystalline structure operative to excite a Lame mode; and forming an interdigital transducer (IDT) structure comprising a first electrode and a second electrode disposed on the piezoelectric layer.

17. A wireless transceiver comprising: a plurality of micro-acoustic resonators, each microacoustic resonator of the plurality of micro-acoustic resonators comprising:WT Ref No. 1173-952Qualcomm Ref No. 2407752 30 an acoustic mirror; a piezoelectric layer having a crystalline structure operative to excite a Lame mode; a bottom electrode layer disposed between the acoustic mirror and a first side of the piezoelectric layer; and an interdigital transducer (IDT) structure comprising a first electrode and a second electrode and disposed on a second side of the piezoelectric layer.WT Ref No. 1173-952

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