WO2018182682A1 - Spurious mode suppression using metal meshed frame around bulk acoustic wave resonators - Google Patents

Spurious mode suppression using metal meshed frame around bulk acoustic wave resonators Download PDF

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Publication number
WO2018182682A1
WO2018182682A1 PCT/US2017/025347 US2017025347W WO2018182682A1 WO 2018182682 A1 WO2018182682 A1 WO 2018182682A1 US 2017025347 W US2017025347 W US 2017025347W WO 2018182682 A1 WO2018182682 A1 WO 2018182682A1
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WIPO (PCT)
Prior art keywords
metal
surface
embodiments
forming
layer
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PCT/US2017/025347
Other languages
French (fr)
Inventor
Edris M. Mohammed
Kimin JUN
Kevin Lin
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Intel Corporation
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Priority to PCT/US2017/025347 priority Critical patent/WO2018182682A1/en
Publication of WO2018182682A1 publication Critical patent/WO2018182682A1/en

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Classifications

    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03HIMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02Details
    • H03H9/02007Details of bulk acoustic wave devices
    • H03H9/02086Means for compensation or elimination of undesirable effects
    • H03H9/02118Means for compensation or elimination of undesirable effects of lateral leakage between adjacent resonators
    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03HIMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezo-electric or electrostrictive resonators or networks
    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03HIMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02Details
    • H03H9/125Driving means, e.g. electrodes, coils
    • H03H9/13Driving means, e.g. electrodes, coils for networks consisting of piezo-electric or electrostrictive materials
    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03HIMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15Constructional features of resonators consisting of piezo-electric or electrostrictive material
    • H03H9/17Constructional features of resonators consisting of piezo-electric or electrostrictive material having a single resonator
    • H03H9/171Constructional features of resonators consisting of piezo-electric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
    • H03H9/172Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
    • H03H9/173Air-gaps
    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03HIMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezo-electric or electrostrictive resonators or networks
    • H03H2003/021Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezo-electric or electrostrictive resonators or networks the resonators or networks being of the air-gap type

Abstract

An apparatus is provided which comprises: a substrate, a piezoelectric resonator separated from a surface of the substrate by a void region, a first electrode coupled to a first surface of the piezoelectric resonator parallel to the substrate surface, and a second electrode coupled to a second surface of the piezoelectric resonator parallel to the substrate surface, the second electrode comprising a solid metal rectangle bordered on at least two sides with a metal mesh. Other embodiments are also disclosed and claimed.

Description

SPURIOUS MODE SUPPRESSION USING METAL MESHED FRAME AROUND BULK

ACOUSTIC WAVE RESONATORS

BACKGROUND

[0001] Resonators are components or systems that oscillate at certain frequencies, known as resonant frequencies, with greater amplitude than at other, often undesired, frequencies, known as spurious modes. One type of resonator, that consists of a piezoelectric material sandwiched between two electrodes and acoustically isolated from the surrounding medium, is a thin-film bulk acoustic resonator (FBAR). FBAR devices may use piezoelectric films with a thickness of as low as fractions of a micrometer and resonate at frequencies from about 100 MHz to 10 GHz. Some applications of FBARs include radio frequency (RF) filters used in wireless communication devices, such as smartphones, in which many radios operating at different frequencies may be integrated. For designing RF band pass filters (Resonator circuits), this spurious mode can cause a spike response in pass band of the filter which deteriorates the filtering function. Also, spurious mode frequencies from one radio may interfere with communications of another radio. Therefore, there is a need for effective spurious mode suppression.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The embodiments of the disclosure will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the disclosure, which, however, should not be taken to limit the disclosure to the specific embodiments, but are for explanation and understanding only.

[0003] Figs. 1A&1B illustrate cross-sectional views of a resonator suitable for implementing metal meshed framing, according to some embodiments,

[0004] Figs. 2A-2F illustrate cross-sectional views of manufacturing steps of metal meshed framing for resonator spurious mode suppression, according to some embodiments,

[0005] Figs. 3A-3F illustrate cross-sectional views of manufacturing steps of metal meshed framing for resonator spurious mode suppression, according to some embodiments,

[0006] Fig. 4 illustrates an overhead view of an example resonator circuit suitable for implementing metal meshed framing, according to some embodiments, [0007] Fig. 5 illustrates a block diagram of an example integrated circuit device with resonator metal meshed framing, according to some embodiments,

[0008] Fig. 6 illustrates a flowchart of a method of forming a resonator with metal meshed framing, according to some embodiments,

[0009] Fig. 7 illustrates a flowchart of a method of forming a resonator with metal meshed framing, according to some embodiments, and

[0010] Fig. 8 illustrates a smart device or a computer system or a SoC (System-on-Chip) which includes an integrated circuit device with resonator metal meshed framing, according to some embodiments.

DETAILED DESCRIPTION

[0011] Metal meshed framing for resonator spurious mode suppression is generally presented. In this regard, embodiments of the present invention enable resonators with an electrode that includes solid metal bordered on at least two sides with a metal mesh that may be designed to transmit a particular frequency while suppressing undesired resonant modes. One skilled in the art would appreciate that these resonators may enable greater integration of smaller and more numerous radios into devices where spurious mode interference may be particularly problematic.

[0012] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present disclosure. It will be apparent, however, to one skilled in the art, that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring embodiments of the present disclosure.

[0013] Note that in the corresponding drawings of the embodiments, signals are represented with lines. Some lines may be thicker, to indicate more constituent signal paths, and/or have arrows at one or more ends, to indicate primary information flow direction. Such indications are not intended to be limiting. Rather, the lines are used in connection with one or more exemplary embodiments to facilitate easier understanding of a circuit or a logical unit. Any represented signal, as dictated by design needs or preferences, may actually comprise one or more signals that may travel in either direction and may be implemented with any suitable type of signal scheme.

[0014] Throughout the specification, and in the claims, the term "connected" means a direct connection, such as electrical, mechanical, or magnetic connection between the things that are connected, without any intermediary devices. The term "coupled" means a direct or indirect connection, such as a direct electrical, mechanical, or magnetic connection between the things that are connected or an indirect connection, through one or more passive or active intermediary devices. The term "circuit" or "module" may refer to one or more passive and/or active components that are arranged to cooperate with one another to provide a desired function. The term "signal" may refer to at least one current signal, voltage signal, magnetic signal, or data/clock signal. The meaning of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on."

[0015] Unless otherwise specified the use of the ordinal adjectives "first," "second," and

"third," etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner.

[0016] For the purposes of the present disclosure, phrases "A and/or B" and "A or B" mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrase "A, B, and/or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C). The terms "left," "right," "front," "back," "top," "bottom," "over," "under," and the like in the description and in the claims, if any, are used for descriptive purposes and not necessari ly for describing permanent relative positions.

[0017] Figs. 1A&1B illustrate cross-sectional views of a resonator suitable for implementing metal meshed framing, according to some embodiments. As shown, resonator 100 includes substrate 102, supports 104, void region 106, lower electrode 108, piezoelectric material 1 10, upper electrode 1 12, and tapered edges 1 14. While shown as an FBAR, resonator 100 may be some other type of resonator, such as a solidly mounted resonator (SMR) or another type of bulk acoustic wave (BAW) resonator for example, while still incorporating teachings of the present invention. Additionally, resonator 100 may be an FBAR with a different topology, such as without supports 104 or with piezoelectric material 1 10 completely suspended at opposite edges over void region 106, for example. [0018] Substrate 102 may be a semiconductor substrate. In some embodiments, substrate

102 is silicon. In other embodiments, substrate 102 is gallium arsenide or another semiconductor material. Supports 104 may be included to provide mechanical support and hold the resonating components of resonator 100 over void region 106. In some embodiments, supports 104 comprise silicon dioxide, though other materials may be used. In some embodiments, supports 104 may include a thin diaphragm that extends over void region 106. Electrodes 108 and 112 may be conductive materials, for example metals such as Cu, Al, Au, W, Pt, Mo, etc. Electrodes 108 and 112 may be part of an electrical circuit to excite piezoelectric material 110 and communicate a resulting signal response.

[0019] Piezoelectric material 110 may include one or more materials with piezoelectric properties. In one embodiment, piezoelectric material 110 comprises aluminum nitride. In another embodiment, piezoelectric material 110 may comprise MN, ZnO or another piezoelectric material.

[0020] As seen in Fig. IB, which represents a cross-sectional view of resonator 100 from the perspective of A- A, electrode 112 includes metal mesh 114, extending outwardly from electrode 112. In some embodiments, electrode 112 is a metal that has been etched to form metal mesh 114. In other embodiments, electrode 112 is a metal that is plated into a pattern that includes metal mesh 114. Metal mesh 1 14 may border two or more sides of electrode 112. In some embodiments, metal mesh 114 includes a substantially uniform width 116 and/or metal-to- space ratio 118 that are chosen based at least in part on a resonant frequency of resonator 100. Metal mesh 114 may include wires oriented in parallel to one of three dimensions or may include wires oriented in random directions. While shown as bordering upper electrode 112, metal mesh 114 may alternatively, or also, border lower electrode 108.

[0021] Figs. 2A-2F illustrate cross-sectional views of manufacturing steps of metal meshed framing for resonator spurious mode suppression, according to some embodiments. As shown in Fig. 2A, assembly 200 includes substrate 202 and sacrificial layer 204. Sacrificial layer 204 may represent one or more layers of dielectric, or other material, that have been built up on substrate 202, which may represent silicon for example, for later removal as part of a void region creation. Any known method of forming sacrificial layer 204 may be utilized, including for example, chemical vapor deposition (CVD). [0022] Fig. 2B shows assembly 210, which may include lower electrode 206 formed on sacrificial layer 204. In some embodiments, lower electrode 206 may be plated or deposited by any known methods.

[0023] As shown in Fig. 2C, assembly 220 has had piezoelectric material 208 formed on lower electrode 206. In some embodiments, piezoelectric material 208 may include a thickness and/or shape designed to produce a predetermined resonant frequency. Piezoelectric material 208 may be an oxide or nitride or other material with piezoelectric properties. While shown as having a width corresponding with that of lower electrode 206, in some embodiments piezoelectric material 208 may have a width that greater or lesser than that of lower electrode 206.

[0024] Turning now to Fig. 2D, assembly 230 may have had metal layer 212 formed on piezoelectric material 208. Metal layer 212 may be a same or different metal from lower electrode 206. In some embodiments, metal layer 212 includes a metal that has the ability to be mechanically or chemically etched using known methods in the art.

[0025] Fig. 2E shows assembly 240, which may have had metal layer 212 etched to form upper electrode 214 and metal mesh 216. In some embodiments, metal layer 212 may be mechanically etched, while in other embodiments, metal layer 212 may be chemically etched. In some embodiments, metal mesh 216 includes substantially wire-shaped portions of metal layer 212 that may be oriented substantially linearly and extend in directions parallel to and orthogonal to upper electrode 214.

[0026] As shown in Fig. 2F, assembly 250 may have had sacrificial layer 204 removed to form void region 218. Any known method of removing sacrificial layer 204 may be utilized, including for example, isotropic etching. Additional processing steps may be necessary to couple electrodes 214 and 206 to additional components, such as additional resonators.

[0027] Figs. 3A-3F illustrate cross-sectional views of manufacturing steps of metal meshed framing for resonator spurious mode suppression, according to some embodiments. As shown in Fig. 3A, assembly 300 includes substrate 302, sacrificial layer 304, lower electrode 306, piezoelectric material 308 and dielectric layer 312. Dielectric layer 312 may be an epoxy or other dielectric material that may have the ability to be patterned using known methods in the art.

[0028] Fig. 3B shows assembly 310, which may have had dielectric layer 312 patterned to form opening 314 and mesh voids 316. In some embodiments, opening 314 may be a rectangular central opening with mesh voids 316 extending out from two or more sides of opening 314. In some embodiments, mesh voids 316 are formed through laser ablation and may include horizontal and vertical voids.

[0029] As shown in Fig. 3C, assembly 320 has had metal plating 318 deposited in opening 314 and mesh voids 316. In some embodiments, metal plating 318 may be copper or another metal that may be able to be plated using methods known in the art.

[0030] Turning now to Fig. 3D, assembly 330 may have had metal plating 318 planarized to surface 322. In some embodiments, mechanical polishing or other methods known in the art are used to planarize metal plating 318.

[0031] Fig. 3E shows assembly 340, which may have had dielectric layer 312 removed to expose upper electrode 324 and metal mesh 326. In some embodiments, selective etching may be utilized to remove dielectric layer 312.

[0032] As shown in Fig. 3F, assembly 350 may have had sacrificial layer 304 removed to form void region 328. Any known method of removing sacrificial layer 304 may be utilized, including for example, isotropic etching. Additional processing steps may be necessary to couple electrodes 324 and 306 to additional components, such as additional resonators.

[0033] Fig. 4 illustrates an overhead view of an example resonator circuit suitable for implementing metal meshed framing, according to some embodiments. As shown, resonator circuit 400 includes substrate 402, resonators 404, electrodes 406, metal mesh 407, piezoelectric material 408, void regions 410 and interconnects 412. While shown as being arranged in a half- ladder configuration, resonator circuit 400 may include any number of resonators 404 in a full- ladder configuration or any other configuration known to one skilled in the art. In some embodiments, resonator circuit 400 is included in an integrated circuit device, such as a filter or sensor.

[0034] Fig. 5 illustrates a block diagram of an example integrated circuit device with resonator metal meshed framing, according to some embodiments. As shown, device 500 includes resonator circuit 400, control circuit 502, transceiver 504, application processor 506, switch 508 and antenna path 510. In some embodiments, resonator circuit 400 is coupled to control circuit 502 by electrodes 406 and interconnects 412. In some embodiments, transceiver 504 is configured to produce an excitation signal that is applied to electrodes 406. The excitation signal may have an alternating current (AC) component that causes piezoelectric material 408 to vibrate. Resonators 404 may have a characteristic frequency response, that manifests itself in variable electrical characteristics, based on their physical characteristics. In some embodiments, the electrical characteristics of resonators 404 are measured by application processor 506. In some embodiments, device 500 may be a filter, a sensor, or some other device that may benefit from the use of resonators.

[0035] In some embodiments, switch 508, which may be a solid state RF switch, may couple resonator circuit 400 with an antenna through antenna path 510. In some embodiments, resonator circuit 400 may function as an RF bandpass filter in cellular, wi-fi, or other wireless communication circuits to allow a specific band of frequencies to be transmitted along antenna path 510. While shown as being included within a single device 500, the components of device 500 may be included in separate devices, combined into other components, or included to greater or lesser extents.

[0036] Fig. 6 illustrates a flowchart of a method of forming a resonator with metal meshed framing, in accordance with some embodiments. Although the blocks in the flowchart with reference to Fig. 6 are shown in a particular order, the order of the actions can be modified. Thus, the illustrated embodiments can be performed in a different order, and some actions/blocks may be performed in parallel. Some of the blocks and/or operations listed in Fig. 6 are optional in accordance with certain embodiments. The numbering of the blocks presented is for the sake of clarity and is not intended to prescribe an order of operations in which the various blocks must occur. Additionally, operations from the various flows may be utilized in a variety of combinations.

[0037] Method 600 begins with forming (602) sacrificial material adjacent a substrate surface, for example sacrificial material 204 may be formed on substrate 202. Next, a lower electrode may be formed (604) adjacent the sacrificial material. For example, lower electrode 206 may be formed on sacrificial material 204 using techniques known in the art.

[0038] Then, the piezoelectric material may be formed (606) adjacent the lower electrode. In some embodiments, piezoelectric material 208 is formed by CVD adjacent lower electrode 206. Next, a solid metal layer may be formed (608) adjacent the piezoelectric material. In some embodiments, solid metal layer 212 comprises a metal that may be easily etched using know techniques in the art.

[0039] The method continues with forming (610) mesh framing from the solid metal layer. In some embodiments, solid metal layer 212 is etched to form a solid metal upper electrode 214 and metal mesh 216. Finally, sacrificial material between the lower electrode and substrate may be removed (612), for example by a wet etch process, to form a void region.

Further processing steps may be taken to add additional interconnect layers and contacts, for example, to complete the resonator device.

[0040] Fig. 7 illustrates a flowchart of a method of forming a resonator with metal meshed framing, in accordance with some embodiments. Although the blocks in the flowchart with reference to Fig. 7 are shown in a particular order, the order of the actions can be modified. Thus, the illustrated embodiments can be performed in a different order, and some actions/blocks may be performed in parallel. Some of the blocks and/or operations listed in Fig. 7 are optional in accordance with certain embodiments. The numbering of the blocks presented is for the sake of clarity and is not intended to prescribe an order of operations in which the various blocks must occur. Additionally, operations from the various flows may be utilized in a variety of combinations.

[0041] Method 700 begins with forming (702) a dielectric layer adjacent piezoelectric material of a resonator. For example, dielectric layer 312 may be formed adjacent piezoelectric material 308. Next, the dielectric layer is patterned (704) to include an opening and mesh voids. For example, dielectric layer 312 may be patterned using techniques known in the art to form a central opening 314 with mesh voids 316 extending outwardly from two or more sides of opening 314.

[0042] Then, the patterned dielectric layer is plated (706) with metal. In some embodiments, metal plating 318 fills opening 314 and mesh voids 316 and extends above dielectric layer 312. Next, the plated metal may be planarized (708). In some embodiments, mechanical polishing or other known techniques are utilized to planarize metal plating 318 down to surface 322.

[0043] The method continues with removing (710) the dielectric layer. In some embodiments, dielectric layer 312 is chemically removed to expose upper electrode 324 and metal mesh 326. Finally, sacrificial material between the lower electrode and substrate may be removed (712), for example by a wet etch process, to form a void region. Further processing steps may be taken to add additional interconnect layers and contacts, for example, to complete the resonator device. [0044] Fig. 8 illustrates a smart device or a computer system or a SoC (System-on-Chip)

800 which includes an integrated circuit device with resonator metal meshed framing, according to some embodiments. In some embodiments, computing device 800 represents a mobile computing device, such as a computing tablet, a mobile phone or smart-phone, a wireless- enabled e-reader, or other wireless mobile device. It will be understood that certain components are shown generally, and not all components of such a device are shown in computing device 800. In some embodiments, one or more components of computing device 800, for example processor 810 and/or connectivity 870, include an integrated circuit device with resonator metal meshed framing as described above.

[0045] For purposes of the embodiments, the transistors in various circuits and logic blocks described here are metal oxide semiconductor (MOS) transistors or their derivatives, where the MOS transistors include drain, source, gate, and bulk terminals. The transistors and/or the MOS transistor derivatives also include Tri-Gate and FinFET transistors, Gate All Around Cylindrical Transistors, Tunneling FET (TFET), Square Wire, or Rectangular Ribbon

Transistors, ferroelectric FET (FeFETs), or other devices implementing transistor functionality like carbon nanotubes or spintronic devices. MOSFET symmetrical source and drain terminals i.e., are identical terminals and are interchangeably used here. A TFET device, on the other hand, has asymmetric Source and Drain terminals. Those skilled in the art will appreciate that other transistors, for example, Bi-polar junction transistors— BJT PNP/NPN, BiCMOS, CMOS, etc., may be used without departing from the scope of the disclosure.

[0046] In some embodiments, computing device 800 includes a first processor 810. The various embodiments of the present disclosure may also comprise a network interface within 870 such as a wireless interface so that a system embodiment may be incorporated into a wireless device, for example, cell phone or personal digital assistant.

[0047] In one embodiment, processor 810 can include one or more physical devices, such as microprocessors, application processors, microcontrollers, programmable logic devices, or other processing means. The processing operations performed by processor 810 include the execution of an operating platform or operating system on which applications and/or device functions are executed. The processing operations include operations related to I/O

(input/output) with a human user or with other devices, operations related to power management, and/or operations related to connecting the computing device 800 to another device. The processing operations may also include operations related to audio I/O and/or display I/O.

[0048] In one embodiment, computing device 800 includes audio subsystem 820, which represents hardware (e.g., audio hardware and audio circuits) and software (e.g., drivers, codecs) components associated with providing audio functions to the computing device. Audio functions can include speaker and/or headphone output, as well as microphone input. Devices for such functions can be integrated into computing device 800, or connected to the computing device 800. In one embodiment, a user interacts with the computing device 800 by providing audio commands that are received and processed by processor 810.

[0049] Display subsystem 830 represents hardware (e.g., display devices) and software

(e.g., drivers) components that provide a visual and/or tactile display for a user to interact with the computing device 800. Display subsystem 830 includes display interface 832, which includes the particular screen or hardware device used to provide a display to a user. In one embodiment, display interface 832 includes logic separate from processor 810 to perform at least some processing related to the display. In one embodiment, display subsystem 830 includes a touch screen (or touch pad) device that provides both output and input to a user.

[0050] I/O controller 840 represents hardware devices and software components related to interaction with a user. I/O controller 840 is operable to manage hardware that is part of audio subsystem 820 and/or display subsystem 830. Additionally, I/O controller 840 illustrates a connection point for additional devices that connect to computing device 800 through which a user might interact with the system. For example, devices that can be attached to the computing device 800 might include microphone devices, speaker or stereo systems, video systems or other display devices, keyboard or keypad devices, or other I/O devices for use with specific applications such as card readers or other devices.

[0051] As mentioned above, I/O controller 840 can interact with audio subsystem 820 and/or display subsystem 830. For example, input through a microphone or other audio device can provide input or commands for one or more applications or functions of the computing device 800. Additionally, audio output can be provided instead of, or in addition to display output. In another example, if display subsystem 830 includes a touch screen, the display device also acts as an input device, which can be at least partially managed by I/O controller 840. There can also be additional buttons or switches on the computing device 800 to provide I/O functions managed by I/O controller 840.

[0052] In one embodiment, I/O controller 840 manages devices such as accelerometers, cameras, light sensors or other environmental sensors, or other hardware that can be included in the computing device 800. The input can be part of direct user interaction, as well as providing environmental input to the system to influence its operations (such as filtering for noise, adjusting displays for brightness detection, applying a flash for a camera, or other features).

[0053] In one embodiment, computing device 800 includes power management 850 that manages battery power usage, charging of the battery, and features related to power saving operation. Memory subsystem 860 includes memory devices for storing information in computing device 800. Memory can include nonvolatile (state does not change if power to the memory device is interrupted) and/or volatile (state is indeterminate if power to the memory device is interrupted) memory devices. Memory subsystem 860 can store application data, user data, music, photos, documents, or other data, as well as system data (whether long-term or temporary) related to the execution of the applications and functions of the computing device 800.

[0054] Elements of embodiments are also provided as a machine-readable medium (e.g., memory 860) for storing the computer-executable instructions. The machine-readable medium (e.g., memory 860) may include, but is not limited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, phase change memory (PCM), or other types of machine-readable media suitable for storing electronic or computer- executable instructions. For example, embodiments of the disclosure may be downloaded as a computer program (e.g., BIOS) which may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals via a communication link (e.g., a modem or network connection).

[0055] Connectivity 870 includes hardware devices (e.g., wireless and/or wired connectors and communication hardware) and software components (e.g., drivers, protocol stacks) to enable the computing device 800 to communicate with external devices. The computing device 800 could be separate devices, such as other computing devices, wireless access points or base stations, as well as peripherals such as headsets, printers, or other devices. [0056] Connectivity 870 can include multiple different types of connectivity. To generalize, the computing device 800 is illustrated with cellular connectivity 872 and wireless connectivity 874. Cellular connectivity 872 refers generally to cellular network connectivity provided by wireless carriers, such as provided via GSM (global system for mobile

communications) or variations or derivatives, CDMA (code division multiple access) or variations or derivatives, TDM (time division multiplexing) or variations or derivatives, or other cellular service standards. Wireless connectivity (or wireless interface) 874 refers to wireless connectivity that is not cellular, and can include personal area networks (such as Bluetooth, Near Field, etc.), local area networks (such as Wi-Fi), and/or wide area networks (such as WiMax), or other wireless communication.

[0057] Peripheral connections 880 include hardware interfaces and connectors, as well as software components (e.g., drivers, protocol stacks) to make peripheral connections. It will be understood that the computing device 800 could both be a peripheral device ("to" 882) to other computing devices, as well as have peripheral devices ("from" 884) connected to it. The computing device 800 commonly has a "docking" connector to connect to other computing devices for purposes such as managing (e.g., downloading and/or uploading, changing, synchronizing) content on computing device 800. Additionally, a docking connector can allow computing device 800 to connect to certain peripherals that allow the computing device 800 to control content output, for example, to audiovisual or other systems.

[0058] In addition to a proprietary docking connector or other proprietary connection hardware, the computing device 800 can make peripheral connections 880 via common or standards-based connectors. Common types can include a Universal Serial Bus (USB) connector (which can include any of a number of different hardware interfaces), DisplayPort including MiniDisplayPort (MDP), High Definition Multimedia Interface (HDMI), Firewire, or other types.

[0059] Reference in the specification to "an embodiment," "one embodiment," "some embodiments," or "other embodiments" means that a particular feature, structure, or

characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of "an

embodiment," "one embodiment," or "some embodiments" are not necessarily all referring to the same embodiments. If the specification states a component, feature, structure, or characteristic "may," "might," or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, that does not mean there is only one of the elements. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[0060] Furthermore, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more embodiments. For example, a first embodiment may be combined with a second embodiment anywhere the particular features, structures, functions, or characteristics associated with the two embodiments are not mutually exclusive

[0061] While the disclosure has been described in conjunction with specific

embodiments thereof, many alternatives, modifications and variations of such embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. The embodiments of the disclosure are intended to embrace all such alternatives, modifications, and variations as to fall within the broad scope of the appended claims.

[0062] In addition, well known power/ground connections to integrated circuit (IC) chips and other components may or may not be shown within the presented figures, for simplicity of illustration and discussion, and so as not to obscure the disclosure. Further, arrangements may be shown in block diagram form in order to avoid obscuring the disclosure, and also in view of the fact that specifics with respect to implementation of such block diagram arrangements are highly dependent upon the platform within which the present disclosure is to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that the disclosure can be practiced without, or with variation of, these specific details. The description is thus to be regarded as illustrative instead of limiting.

[0063] The following examples pertain to further embodiments. Specifics in the examples may be used anywhere in one or more embodiments. All optional features of the apparatus described herein may also be implemented with respect to a method or process.

[0064] In one example, an apparatus is provided comprising: a substrate; a piezoelectric resonator separated from a surface of the substrate by a void region; a first electrode coupled to a first surface of the piezoelectric resonator parallel to the substrate surface; and a second electrode coupled to a second surface of the piezoelectric resonator parallel to the substrate surface, the second electrode comprising a solid metal bordered on at least two sides with a metal mesh.

[0065] In some embodiments, the metal mesh comprises a plurality of metal wire extending orthogonally from a surface of the solid metal and a plurality of metal wire parallel to the surface of the solid metal. In some embodiments, the metal mesh comprises a width chosen based at least in part on a resonant frequency of the piezoelectric resonator. In some

embodiments, the metal mesh comprises a metal-to-space ratio chosen based at least in part on a resonant frequency of the piezoelectric resonator. In some embodiments, the metal mesh comprises a metal chosen from the group consisting of: Al, Au, W, Pt, and Mo. In some embodiments, the metal mesh comprises copper.

[0066] In another example, a system is provided comprising: a display subsystem; a wireless communication interface; and an integrated circuit device, the integrated circuit device comprising a film bulk acoustic resonator (FBAR) comprising: a substrate; a piezoelectric resonator separated from a surface of the substrate by a void region; a first electrode coupled to a first surface of the piezoelectric resonator parallel to the substrate surface; and a second electrode coupled to a second surface of the piezoelectric resonator parallel to the substrate surface, the second electrode comprising a solid metal bordered on at least two sides with a metal mesh.

[0067] In some embodiments, the metal mesh comprises a plurality of metal wire extending orthogonally from a surface of the solid metal and a plurality of metal wire parallel to the surface of the solid metal. In some embodiments, the metal mesh comprises a width chosen based at least in part on a resonant frequency of the piezoelectric resonator. In some

embodiments, the metal mesh comprises a metal-to-space ratio chosen based at least in part on a resonant frequency of the piezoelectric resonator. In some embodiments, the metal mesh comprises a metal chosen from the group consisting of: Al, Au, W, Pt, and Mo. Some embodiments also include the solid metal bordered on four sides with the metal mesh.

[0068] In another example, a method is provided comprising: forming a sacrificial material layer over a substrate surface; forming a first metal layer over the sacrificial material layer; forming a piezoelectric material layer over the metal layer; forming a second metal layer over the piezoelectric material layer; and patterning the second metal layer to form a meshed frame on at least two sides of the second metal layer. [0069] In some embodiments, patterning the second metal layer comprises performing a wet etch process. In some embodiments, patterning the second metal layer comprises forming a meshed frame on four side of the second metal layer. In some embodiments, the meshed frame comprises a plurality of metal wire extending orthogonally from a surface of the second metal layer and a plurality of metal wire parallel to the surface of the second metal layer. In some embodiments, the second metal layer comprises a metal chosen from the group consisting of: Al, Au, W, Pt, and Mo. Some embodiments also include removing the sacrificial material layer to create a void region between the substrate surface and the first metal layer.

[0070] In another example, a method is provided comprising: forming a sacrificial material layer over a substrate surface; forming a first metal layer over the sacrificial material layer; forming a piezoelectric material layer over the metal layer; forming a dielectric layer over the piezoelectric material layer; patterning the dielectric layer to form a central opening framed on at least two sides with a plurality of wire-shaped voids; and plating the patterned dielectric layer to form a solid metal with a meshed frame on at least two sides.

[0071] In some embodiments, plating the patterned dielectric layer comprises copper plating. Some embodiments also include polishing the metal plating and removing the patterned dielectric layer. In some embodiments, patterning the dielectric layer comprises forming a central opening framed on four sides with a plurality of wire-shaped voids. Some embodiments also include forming interconnects to couple the solid metal with a plurality of resonators. In some embodiments, the plurality of wire-shaped voids comprise voids extending orthogonally from the central opening. Some embodiments also include removing the sacrificial material layer to create a void region between the substrate surface and the first metal layer.

[0072] In another example, a bulk acoustic wave (BAW) resonator is provided comprising: means for supporting a piezoelectric resonator body over a void region; and means for conducting electrical signals generated by the piezoelectric resonator body, the wherein the means for conducting comprises means for suppressing spurious modes of the BAW resonator.

[0073] In some embodiments, the means for suppressing spurious modes comprises a plurality of metal wire extending orthogonally from a surface of a solid metal and a plurality of metal wire parallel to the surface of the solid metal. In some embodiments, the means for suppressing spurious modes comprises a width chosen based at least in part on a resonant frequency of the piezoelectric resonator. In some embodiments, the means for suppressing spurious modes comprises a metal-to-space ratio chosen based at least in part on a resonant frequency of the piezoelectric resonator. In some embodiments, the means for suppressing spurious modes comprises a metal chosen from the group consisting of: Al, Au, W, Pt, and Mo. In some embodiments, the means for suppressing spurious modes comprises copper. In some embodiments, the means for suppressing spurious modes comprises a solid metal bordered on two or more sides with a metal mesh.

[0074] In another example, a wireless communication system is provided comprising: a processor; a display subsystem; and a wireless communication interface, the wireless

communication interface comprising an antenna and a film bulk acoustic resonator (FBAR) coupled with the antenna to provide bandpass filtering, the FBAR comprising: a substrate; a piezoelectric resonator separated from a surface of the substrate by a void region; a first electrode coupled to a first surface of the piezoelectric resonator parallel to the substrate surface; and a second electrode coupled to a second surface of the piezoelectric resonator parallel to the substrate surface, the second electrode comprising a solid metal bordered on at least two sides with a metal mesh.

[0075] In some embodiments, the metal mesh comprises a plurality of metal wire extending orthogonally from a surface of the solid metal and a plurality of metal wire parallel to the surface of the solid metal. In some embodiments, the metal mesh comprises a width chosen based at least in part on a resonant frequency of the piezoelectric resonator. In some

embodiments, the metal mesh comprises a metal-to-space ratio chosen based at least in part on a resonant frequency of the piezoelectric resonator. In some embodiments, the metal mesh comprises a metal chosen from the group consisting of: Al, Au, W, Pt, and Mo. In some embodiments, the metal mesh comprises copper. Some embodiments also include the solid metal bordered on four sides with the metal mesh.

[0076] An abstract is provided that will allow the reader to ascertain the nature and gist of the technical disclosure. The abstract is submitted with the understanding that it will not be used to limit the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.

Claims

CLAIMS We claim:
1. An apparatus comprising:
a substrate;
a piezoelectric resonator separated from a surface of the substrate by a void region;
a first electrode coupled to a first surface of the piezoelectric resonator parallel to the substrate surface; and
a second electrode coupled to a second surface of the piezoelectric resonator parallel to the substrate surface, the second electrode comprising a solid metal bordered on at least two sides with a metal mesh.
2. The apparatus of claim 1, wherein the metal mesh comprises a plurality of metal wire
extending orthogonally from a surface of the solid metal and a plurality of metal wire parallel to the surface of the solid metal.
3. The apparatus of claim 1, wherein the metal mesh comprises a width chosen based at least in part on a resonant frequency of the piezoelectric resonator.
4. The apparatus of claim 1, wherein the metal mesh comprises a metal-to-space ratio chosen based at least in part on a resonant frequency of the piezoelectric resonator.
5. The apparatus according to any one of claims 1 to 4, wherein the metal mesh comprises a metal chosen from the group consisting of: Al, Au, W, Pt, and Mo.
6. The apparatus according to any one of claims 1 to 4, wherein the metal mesh comprises
copper.
7. A system comprising:
a display subsystem;
a wireless communication interface; and an integrated circuit device, the integrated circuit device comprising a film bulk acoustic resonator (FBAR) comprising:
a substrate;
a piezoelectric resonator separated from a surface of the substrate by a void region;
a first electrode coupled to a first surface of the piezoelectric resonator parallel to the substrate surface; and
a second electrode coupled to a second surface of the piezoelectric resonator parallel to the substrate surface, the second electrode comprising a solid metal bordered on at least two sides with a metal mesh.
8. The system of claim 7, wherein the metal mesh comprises a plurality of metal wire extending orthogonally from a surface of the solid metal and a plurality of metal wire parallel to the surface of the solid metal.
9. The system of claim 7, wherein the metal mesh comprises a width chosen based at least in part on a resonant frequency of the piezoelectric resonator.
10. The system of claim 7, wherein the metal mesh comprises a metal-to-space ratio chosen based at least in part on a resonant frequency of the piezoelectric resonator.
11. The system of any of claims 7 to 10, wherein the metal mesh comprises a metal chosen from the group consisting of: Al, Au, W, Pt, and Mo.
12. The system of any of claims 7 to 10, further comprising the solid metal bordered on four sides with the metal mesh.
13. A method comprising:
forming a sacrificial material layer over a substrate surface;
forming a first metal layer over the sacrificial material layer;
forming a piezoelectric material layer over the metal layer; forming a second metal layer over the piezoelectric material layer; and patterning the second metal layer to form a meshed frame on at least two sides of the second metal layer.
14. The method of claim 13, wherein patterning the second metal layer comprises performing a wet etch process.
15. The method of claim 13, wherein patterning the second metal layer comprises forming a meshed frame on four side of the second metal layer.
16. The method of claim 13, wherein the meshed frame comprises a plurality of metal wire extending orthogonally from a surface of the second metal layer and a plurality of metal wire parallel to the surface of the second metal layer.
17. The method according to any one of claims 13 to 16, wherein the second metal layer
comprises a metal chosen from the group consisting of: Al, Au, W, Pt, and Mo.
18. The method according to any one of claims 13 to 16, further comprising removing the
sacrificial material layer to create a void region between the substrate surface and the first metal layer.
19. A method comprising:
forming a sacrificial material layer over a substrate surface;
forming a first metal layer over the sacrificial material layer;
forming a piezoelectric material layer over the metal layer;
forming a dielectric layer over the piezoelectric material layer;
patterning the dielectric layer to form a central opening framed on at least two sides with a plurality of wire-shaped voids; and
plating the patterned dielectric layer to form a solid metal with a meshed frame on at least two sides.
20. The method of claim 19, wherein plating the patterned dielectric layer comprises copper plating.
21. The method of claim 19, further comprising polishing the metal plating and removing the patterned dielectric layer.
22. The method of claim 19, wherein patterning the dielectric layer comprises forming a central opening framed on four sides with a plurality of wire-shaped voids.
23. The method of any of claims 19 to 22, further comprising forming interconnects to couple the solid metal with a plurality of resonators.
24. The method of any of claims 19 to 22, wherein the plurality of wire-shaped voids comprise voids extending orthogonally from the central opening.
25. The method of any of claims 19 to 22, further comprising removing the sacrificial material layer to create a void region between the substrate surface and the first metal layer.
PCT/US2017/025347 2017-03-31 2017-03-31 Spurious mode suppression using metal meshed frame around bulk acoustic wave resonators WO2018182682A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07240661A (en) * 1994-02-25 1995-09-12 Ngk Spark Plug Co Ltd High frequency piezoelectric ladder filter
US5519279A (en) * 1994-09-29 1996-05-21 Motorola, Inc. Piezoelectric resonator with grid-like electrodes
US20110298564A1 (en) * 2009-02-20 2011-12-08 Kazuki Iwashita Thin-Film Piezoelectric Resonator and Thin-Film Piezoelectric Filter Using the Same
US20140354115A1 (en) * 2011-09-14 2014-12-04 Avago Technologies General Ip (Singapore) Pte. Ltd. Solidly mounted acoustic resonator having multiple lateral features
US9160305B1 (en) * 2012-10-10 2015-10-13 University Of South Florida Capacitively and piezoelectrically transduced micromechanical resonators

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07240661A (en) * 1994-02-25 1995-09-12 Ngk Spark Plug Co Ltd High frequency piezoelectric ladder filter
US5519279A (en) * 1994-09-29 1996-05-21 Motorola, Inc. Piezoelectric resonator with grid-like electrodes
US20110298564A1 (en) * 2009-02-20 2011-12-08 Kazuki Iwashita Thin-Film Piezoelectric Resonator and Thin-Film Piezoelectric Filter Using the Same
US20140354115A1 (en) * 2011-09-14 2014-12-04 Avago Technologies General Ip (Singapore) Pte. Ltd. Solidly mounted acoustic resonator having multiple lateral features
US9160305B1 (en) * 2012-10-10 2015-10-13 University Of South Florida Capacitively and piezoelectrically transduced micromechanical resonators

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