Ultrasonic fingerprint sensor with non-conductive acoustic layer

Abstract

The ultrasonic fingerprint sensor system disclosed herein may be provided with a thick non-conductive acoustic layer and a thin electrode layer, both of which are piezoelectric layers coupled to an ultrasonic transmitter or transceiver. The thick non-conductive acoustic layer may have a high density or high acoustic impedance value and may be adjacent to the piezoelectric layer. The thin electrode layer may be divided into individual electrode segments. The ultrasonic fingerprint sensor system may use a flexible or rigid substrate and may use an ultrasonic transceiver or an ultrasonic transmitter separate from the ultrasonic receiver.

Description

[0001] Priority claim according to 35 U.SC § 119

[0002] This patent application claims priority to non-provisional application No. 16 / 252,408, filed on January 18, 2019, entitled “ULTRASONIC FINGERPRINT SENSORWITH ELECTRICALLY NONCONDUCTIVE ACOUSTIC LAYER”, which has been assigned to its assignee and is hereby expressly incorporated by reference. Technical Field

[0003] This disclosure generally relates to ultrasonic fingerprint sensor systems, and more specifically to ultrasonic fingerprint sensor systems including a non-conductive acoustic layer.

[0004] Related technical descriptions

[0005] In an ultrasonic sensor system, an ultrasonic transmitter can be used to send ultrasonic waves toward an object to be detected via an ultrasonic transmission medium or medium. The transmitter can be operatively coupled to an ultrasonic sensor configured to detect portions of the ultrasonic waves reflected from the object. For example, in an ultrasonic fingerprint imager, ultrasonic pulses can be generated by starting and stopping the transmitter over a very short time interval. At each material interface encountered by the ultrasonic pulse, a portion of the ultrasonic pulse is reflected.

[0006] For example, in the context of an ultrasonic fingerprint imager, ultrasonic waves travel through a pressure plate on which a person's finger can be placed to obtain a fingerprint image. After passing through the pressure plate, some portions of the ultrasonic waves encounter the skin in contact with the pressure plate (e.g., fingerprint ridges), while other portions encounter air (e.g., valleys between adjacent ridges of the fingerprint) and can be reflected back to the ultrasonic sensor at varying intensities. The reflected signals associated with the finger can be processed and converted into digital values ​​representing the signal strength of the reflected signals. When multiple such reflected signals are collected over a distributed area, these digital values ​​can be used to generate a graphical display of the signal strength over the distributed area, such as by converting the digital values ​​into an image, thereby producing an image of the fingerprint. Therefore, an ultrasonic sensor system can be used as a fingerprint imager or other types of biometric scanner. In some implementations, the detected signal strength can be mapped to a finger profile map representing the depth of the ridge structure details.

[0007] Ultrasonic sensor systems can be incorporated into display devices as fingerprint sensor systems for user authentication. Advances in display devices have led to flexible displays, three-dimensional overlays, and bezel-less designs. Therefore, an increasing number of display devices have limited space to incorporate discrete buttons for fingerprint sensor systems or under-glass fingerprint sensor systems located on the periphery of the display. Under-glass and under-display fingerprint sensor systems can provide additional functionality and space to display devices, and can also open up additional authentication software applications for improved user interfaces.

[0008] Overview

[0009] Each of the devices, systems and methods disclosed herein has several aspects, and no single aspect is solely responsible for the desired properties disclosed herein.

[0010] One aspect of the subject matter of this disclosure can be implemented in an ultrasonic fingerprint sensor system. The ultrasonic fingerprint sensor system includes: a substrate having multiple sensor circuits; an ultrasonic transceiver above the substrate and including a piezoelectric layer configured to generate ultrasonic waves; a non-conductive high acoustic impedance layer adjacent to and above the piezoelectric layer; and one or more conductive layers between the piezoelectric layer and the non-conductive high acoustic impedance layer. The thickness of the non-conductive high acoustic impedance layer is significantly greater than the thickness of each of the one or more conductive layers.

[0011] In some implementations, the non-conductive high acoustic impedance layer comprises a dielectric material having an acoustic impedance value greater than about 8.0 MRayl (megaray il). In some implementations, the one or more conductive layers comprise an electrode layer disposed on the piezoelectric layer, wherein the electrode layer comprises a plurality of electrode segments. In some implementations, the average gap distance between adjacent segments of the plurality of electrode segments is equal to or less than about 200 μm. In some implementations, the plurality of electrode segments are arranged as strips having electrically insulating gaps separating the plurality of electrode segments along a lateral dimension of the ultrasonic fingerprint sensor system. In some implementations, the plurality of electrode segments are arranged as a 2-D island array having electrically insulating gaps separating the 2-D islands along lateral dimensions orthogonal to each other in the ultrasonic fingerprint sensor system. In some implementations, the thickness of each of the one or more conductive layers is between about 10 nm and about 2 μm. In some implementations, each of the one or more conductive layers comprises aluminum, nickel, copper, or a combination thereof. In some implementations, the substrate is a flexible substrate, and the non-conductive high acoustic impedance layer is placed in the acoustic path of the ultrasonic waves between the piezoelectric layer and the display, with the ultrasonic fingerprint sensor system configured to be attached to the display. In some implementations, the substrate is a rigid substrate, and the non-conductive high acoustic impedance layer is placed on the side of the substrate opposite to the display, with the ultrasonic fingerprint sensor system configured to be attached to the display.

[0012] Another innovative aspect of the subject matter described in this disclosure can be implemented in an ultrasonic fingerprint sensor system. The ultrasonic fingerprint sensor system includes: a substrate having multiple sensor circuits; and an ultrasonic transmitter comprising: a piezoelectric emitter layer configured to generate ultrasonic waves; a non-conductive high acoustic impedance layer adjacent to the piezoelectric emitter layer; and a first conductive layer between the non-conductive high acoustic impedance layer and the piezoelectric emitter layer. The thickness of the non-conductive high acoustic impedance layer is significantly greater than the thickness of the first conductive layer. The ultrasonic fingerprint sensor system further includes an ultrasonic receiver, wherein the ultrasonic receiver includes a piezoelectric receiver layer configured to receive reflections of ultrasonic waves.

[0013] In some implementations, the non-conductive high acoustic impedance layer comprises a dielectric material having an acoustic impedance value greater than about 8.0 MRayl. In some implementations, the first conductive layer comprises multiple electrode segments. In some implementations, the ultrasonic transmitter further comprises a second conductive layer on the side of the piezoelectric transmitter layer opposite the first conductive layer. In some implementations, the second conductive layer comprises multiple electrode segments and the first conductive layer is continuous across the ultrasonic transmitter, wherein the thickness of the second conductive layer is significantly greater than the thickness of the first conductive layer. In some implementations, the thickness of the first conductive layer is between about 10 nm and about 2 μm. In some implementations, the first conductive layer comprises aluminum, nickel, copper, or a combination thereof. In some implementations, the substrate is a rigid substrate, and the ultrasonic receiver is above the substrate and the ultrasonic transmitter is below the substrate, wherein the non-conductive high acoustic impedance layer is between the piezoelectric transmitter layer and the substrate. In some implementations, the substrate is a flexible substrate, and the ultrasonic receiver is above the substrate and the ultrasonic transmitter is above the ultrasonic receiver, wherein the non-conductive high acoustic impedance layer is above the piezoelectric transmitter layer. Brief description of the attached diagram

[0015] Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from this description, the drawings, and the claims. It should be noted that the relative dimensions of the following drawings may not be drawn to scale.

[0016] Similar reference numerals and naming conventions in the various figures indicate similar elements.

[0017] Figure 1 A front view of an illustrated representation of an example mobile device including an ultrasonic sensing system is shown.

[0018] Figure 2A A block diagram representation of the components of an example ultrasonic sensing system based on some implementations is shown.

[0019] Figure 2B It shows including Figure 2A A block diagram representation of the components of an example mobile device for an ultrasonic sensing system.

[0020] Figure 3A A cross-sectional projection diagram is shown, illustrating a portion of an example ultrasonic sensing system based on some implementations.

[0021] Figure 3B It shows some implementations Figure 3A An enlarged cross-sectional side view of an example ultrasonic sensing system.

[0022] Figure 4A It shows some implementations Figures 3A-3BAn exploded projection diagram of an example component of an example ultrasonic sensing system.

[0023] Figure 4B It shows some implementations Figures 3A-3B An exploded projection diagram of an example component of an ultrasonic transceiver array in an ultrasonic sensor system.

[0024] Figure 5 A cross-sectional view of an example underplate ultrasonic sensor system with flexible printed circuit (FPC) is shown.

[0025] Figure 6 An example of using a fingerprint sensor when it is not located below the display is shown.

[0026] Figure 7 An example of using a fingerprint sensor with the fingerprint sensor located below the display is shown, based on some implementations.

[0027] Figure 8 An image of an example display device is shown, based on some implementations, in which the fingerprint sensor is located below the display and spans the entire display area.

[0028] Figure 9 A cross-sectional schematic diagram of an example display device including an ultrasonic fingerprint sensor system under the display, according to some implementations, is shown.

[0029] Figures 10A-10C A schematic cross-sectional view of the individual electrode layers coupled to an ultrasonic transmitter / transceiver configured to generate ultrasonic waves, according to some implementations, is shown.

[0030] Figure 11A A cross-sectional schematic diagram of an example ultrasonic fingerprint sensor system with a rigid substrate below a display, according to some implementations, is shown.

[0031] Figure 11B A cross-sectional schematic diagram of an example ultrasonic fingerprint sensor system with a flexible substrate under a display, according to some implementations, is shown.

[0032] Figure 12A A schematic cross-sectional view of an example ultrasonic fingerprint sensor system with a rigid substrate and a non-conductive acoustic layer, according to some implementations, is shown.

[0033] Figure 12B A schematic cross-sectional view of an example ultrasonic fingerprint sensor system with a flexible substrate and a non-conductive acoustic layer, according to some implementations, is shown.

[0034] Figure 13AA schematic cross-sectional view of an example ultrasonic fingerprint sensor system with a rigid substrate, a non-conductive acoustic layer, and multiple conductive layers, according to some implementations, is shown.

[0035] Figure 13B A schematic cross-sectional view of an example ultrasonic fingerprint sensor system with a flexible substrate, a non-conductive acoustic layer, and multiple conductive layers, according to some implementations, is shown.

[0036] Figures 14A-14C A cross-sectional schematic diagram of various example ultrasonic fingerprint sensor systems implemented on a rigid substrate and having separate ultrasonic transmitters and receivers is shown.

[0037] Figures 15A-15C A cross-sectional schematic diagram of various example ultrasonic fingerprint sensor systems implemented on a flexible substrate and having separate ultrasonic transmitters and receivers is shown.

[0038] Figure 16A A schematic diagram of an example ultrasonic fingerprint sensor system with segmented electrodes employing a "strip" design, based on some implementations, is shown.

[0039] Figure 16B A schematic diagram of an example ultrasonic fingerprint sensor system with segmented electrodes employing a "2-D island" design, based on some implementations, is shown.

[0040] Figures 17A-17B The diagram shows cross-sectional schematics of various stages in an example method for manufacturing an ultrasonic fingerprint sensor system with segmented electrodes of an ultrasonic transceiver employing a “strip” design, according to some implementations.

[0041] Figures 18A-18D The diagram shows cross-sectional schematics of various stages in an example method for manufacturing an ultrasonic fingerprint sensor system with segmented electrodes of an ultrasonic transceiver employing a “2-D island” design, according to some implementations.

[0042] Figures 19A-19F The diagram shows cross-sectional schematics of various stages in an example method for manufacturing an ultrasonic fingerprint sensor system with segmented electrodes employing an ultrasonic transmitter with a “strip” design, according to some implementations.

[0043] Figures 20A-20H The diagram shows cross-sectional schematics of various stages in an example method for manufacturing an ultrasonic fingerprint sensor system with segmented electrodes employing an ultrasonic transmitter with a “2-D island” design, according to some implementations.

[0044] Detailed description

[0045] The following description is directed to certain implementations in order to describe the inventive aspects of this disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in many different ways. The described implementations can be implemented in any device, apparatus, or system, including biometric systems for ultrasound sensing as disclosed herein. Furthermore, the described implementations are contemplated as being included in or associated with a variety of electronic devices, such as, but not limited to: mobile phones, Internet-enabled multimedia cellular phones, mobile TV receivers, wireless devices, smartphones, smart cards, wearable devices (such as wristbands, armbands, wrist straps, rings, headbands, and patches, etc.). Devices, Personal Data Assistants (PDAs), Wireless Email Receivers, Handheld or Portable Computers, Netbooks, Notebooks, Smartbooks, Tablets, Printers, Copiers, Scanners, Fax Equipment, Global Positioning System (GPS) Receivers / Navigators, Cameras, Digital Multimedia Players (such as MP3 Players), Camcorders, Game Consoles, Wristwatches, Clocks, Calculators, Television Monitors, Flat Panel Displays, Electronic Reading Devices (e.g., E-readers), Mobile Health Devices, Computer Monitors, Automatic Displays (including odometer and speedometer displays, etc.), Cockpit Controls and / or Displays, Cameras This includes machine-view displays (such as displays for rearview cameras in vehicles), electronic photographs, electronic billboards or signs, projectors, building structures, microwave ovens, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable storage chips, washing machines, dryers, washer / dryer systems, ATMs, parking timers, packages (such as in electromechanical systems (EMS) applications, including microelectromechanical systems (MEMS) applications, along with non-EMS applications), aesthetic structures (such as image displays on a piece of jewelry or clothing), and various EMS devices. The teachings herein can also be applied to applications such as, but not limited to, electronic switching devices, radio frequency filters, sensors, accelerometers, gyroscopes, motion sensing devices, magnetometers, inertial components for consumer electronic devices, components for consumer electronic products, varactor tubes, liquid crystal devices, electrophoresis equipment, drive schemes, manufacturing processes, and electronic test equipment. Therefore, these teachings are not intended to be limited to the implementations depicted in the figures, but have a broad applicability as will be apparent to those skilled in the art.

[0046] Fingerprint sensor systems can be useful and effective in authenticating users for electronic devices. Capacitive fingerprint sensors require electromagnetic signals that may interfere with the electrical functions of the display. Signals generated or transmitted within the display, along with associated conductive traces, can reduce the sensing capability of capacitive fingerprints. Optical fingerprint systems may be limited or rendered useless in display devices that include light-blocking layers or numerous metal traces. Ultrasonic fingerprint sensors use ultrasound to produce a detailed reproduction of the scanned fingerprint. Ultrasonic fingerprint sensors for fingerprint scanning can be incorporated into display devices. Ultrasonic fingerprint sensors can emit and receive ultrasound waves that penetrate electrical shielding and light-blocking layers. Therefore, ultrasonic imaging of fingerprints is largely unaffected by small features, touchscreen electrodes, or pixels in various display types. Ultrasonic fingerprint sensors can be incorporated "below the display" or "inside the display" so that fingerprint scanning can be performed within the display area.

[0047] Many ultrasonic fingerprint sensor systems can be attached to or incorporated into displays using organic light-emitting diode (OLED) displays or active-matrix organic light-emitting diode (AMOLED) displays. Some displays disclosed herein can be provided in pOLED displays, which may also be referred to as flexible OLED displays. Some configurations and techniques for ultrasonic fingerprint sensor systems are applicable to flexible displays, curved displays, curved cover glass, and emerging 2.5D or 3D displays.

[0048] An ultrasonic fingerprint sensor system disclosed herein may be provided with a non-conductive acoustic layer adjacent to a piezoelectric layer. This non-conductive acoustic layer is a high-density layer providing acoustic coupling with the piezoelectric layer of an ultrasonic transmitter or transceiver. In this manner, ultrasonic waves can be propagated with minimal acoustic interference, and reflected ultrasonic waves can be detected by the ultrasonic fingerprint sensor system with minimal acoustic interference. A conductive layer (such as an electrode layer divided into multiple electrode segments) is placed on the piezoelectric layer and positioned between the non-conductive acoustic layer and the piezoelectric layer. The non-conductive acoustic layer is extremely thick compared to the conductive layer. Instead of using extremely thick metal electrodes adjacent to the piezoelectric layer, which could result in undesirable large gaps between the electrode segments, this disclosure provides a combination of an extremely thick non-conductive acoustic layer and an extremely thin conductive layer, wherein the extremely thin conductive layer can be deposited with significantly smaller gaps between the electrode segments. In some implementations, the ultrasonic fingerprint sensor system includes a substrate, such as a flexible substrate (e.g., a polyimide substrate) or a rigid substrate (e.g., a glass substrate). In some implementations, the ultrasonic fingerprint sensor system includes an ultrasonic transceiver, or the ultrasonic fingerprint sensor system includes an ultrasonic transmitter separate from the ultrasonic receiver.

[0049] Specific implementations of the subject matter described herein can be achieved to attain one or more of the following potential advantages. The inclusion of a non-conductive acoustic layer provides a layer with high density and / or high acoustic impedance to enhance acoustic coupling in the ultrasonic fingerprint sensor system, thereby limiting distortion from acoustic interference and enhancing image quality. An extremely thick non-conductive acoustic layer is provided with an extremely thin conductive layer divided into multiple electrode segments, wherein these multiple electrode segments have small gaps. Dividing the electrode segments into multiple segments reduces the transmitter capacitance, which lowers the voltage required to drive the ultrasonic transmitter / transceiver. This reduces the peak current required to be supplied to the ultrasonic fingerprint sensor system. Furthermore, having small gaps between the electrode segments, rather than large gaps, improves image quality by minimizing image discontinuities and artifacts. In some implementations, the use of a flexible substrate allows the ultrasonic fingerprint sensor system to be provided in the display beyond the localized small area used for fingerprint scanning. This enables ultrasonic fingerprint sensing to span a much larger area, even across the entire display area, enabling continuous user authentication and finger verification at any location on the display. Therefore, using a flexible substrate allows for a larger active area for the sensor, which increases the functionality of the display area, improves performance, allows for greater flexibility in sensor placement, and provides a better user experience. Furthermore, a larger active area allows for more authentication levels by scanning more fingers, palm prints, or fingerprints. Flexible substrates enable flexible fingerprint sensors to be incorporated into flexible electronics, 3D displays, and curved displays to achieve greater functionality.

[0050] Figure 1 A schematic representation of an example mobile device 100 including an ultrasonic sensing system is shown. Mobile device 100 can represent, for example, various portable computing devices such as cellular phones, smartphones, smartwatches, multimedia devices, personal gaming devices, tablet computers, and laptop computers, as well as other types of portable computing devices. However, the various implementations described herein are not limited to applications in portable computing devices. In fact, the various techniques and principles disclosed herein can be applied to conventional non-portable devices and systems, such as computer monitors, television displays, kiosks, vehicle navigation devices, and audio systems, as well as other applications. Furthermore, the various implementations described herein are not limited to applications in devices including displays.

[0051] Mobile device 100 generally includes a housing 102 (also referred to herein as a "housing" or "shell") in which various circuits, sensors, and other electrical components reside. In the illustrated example implementation, mobile device 100 also includes a touchscreen display (also referred to herein as a "touch-sensitive display") 104. Touchscreen display 104 generally includes a display and a touchscreen disposed on or otherwise incorporated into or integrated with the display. Display 104 may generally represent any of a variety of suitable display types employing any of a variety of suitable display technologies. For example, display 104 may be a digital micro-shutter (DMS) based display, a light-emitting diode (LED) display, an organic LED (OLED) display, a liquid crystal display (LCD), an LCD display using LEDs as backlight, a plasma display, an interferometric modulator-modulator-display (IMOD) based display, or another type of display suitable for use in conjunction with a touch-sensitive user interface (UI) system.

[0052] Mobile device 100 may include various other devices or components for interacting with a user or otherwise conveying or receiving information from a user. For example, mobile device 100 may include one or more microphones 106, one or more speakers 108, and in some cases, one or more buttons 110 that are at least partially mechanical. Mobile device 100 may include various other components that implement additional features, such as, for example, one or more video or still image cameras 112, one or more wireless network interfaces 114 (e.g., Bluetooth, Wi-Fi, or cellular), and one or more non-wireless interfaces 116 (e.g., a Universal Serial Bus (USB) interface or an HDMI interface).

[0053] Mobile device 100 may include an ultrasonic sensing system 118 capable of scanning and imaging object signatures (such as fingerprints, palm prints, or handprints). Typically, such as Figure 1 As shown, the ultrasonic sensing system 118 can be used as a touch-sensitive control button. The touch-sensitive control button can be implemented by a mechanical or electrical pressure-sensitive system located below or otherwise integrated with the ultrasonic sensing system 118. In other words, the area occupied by the ultrasonic sensing system 118 can be used as both a user input button for controlling the mobile device 100 and a fingerprint sensor for implementing security features such as user authentication features. In some implementations, the ultrasonic sensing system 118 can be located under the cover glass of the display or under a portion of the display itself, as described herein. In some implementations, the ultrasonic sensing system 118 can be located under at least the entire display itself, as described herein, thereby allowing the active area of ​​the sensor to span the entire display. In some implementations, the ultrasonic sensing system 118 can be located on the side wall or back of the mobile device housing 102.

[0054] Figure 2A A block diagram representation of the components of an example ultrasonic sensing system 200 according to some implementations is shown. As shown, the ultrasonic sensing system 200 may include a sensor system 202 and a control system 204 electrically coupled to the sensor system 202. The sensor system 202 may be able to scan an object and provide raw measured image data that can be used to obtain object features (such as, for example, fingerprints of a human finger). The control system 204 may be able to control the sensor system 202 and process the raw measured image data received from the sensor system. In some implementations, the ultrasonic sensing system 200 may include an interface system 206 capable of transmitting or receiving data, such as raw or processed measured image data, to or from various components within or integrated with the ultrasonic sensing system 100, or, in some implementations, to or from various components, devices, or other systems outside the ultrasonic sensing system.

[0055] Figure 2B It shows including Figure 2A A block diagram representation of the components of an example mobile device 210 for an ultrasonic sensing system 200. For example, the mobile device 210 may be in... Figure 1 As shown in the above reference Figure 1 A block diagram of the described mobile device 100 is shown. The sensor system 202 of the ultrasonic sensing system 200 of the mobile device 210 can be implemented using an ultrasonic sensor array 212. The control system 204 of the ultrasonic sensing system 200 can be implemented using a controller 214 electrically coupled to the ultrasonic sensor array 212. Although the controller 214 is shown and described as a single component, in some implementations, the controller 214 may be collectively referred to as two or more distinct control units or processing units in electrical communication with each other. In some implementations, the controller 214 may include one or more of the following: a general-purpose single-chip or multi-chip processor, a central processing unit (CPU), a digital signal processor (DSP), an application processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions and operations described herein.

[0056] Figure 2BThe ultrasonic sensing system 200 may include an image processing module 218. In some implementations, raw measured image data provided by the ultrasonic sensor array 212 may be sent, transmitted, communicated, or otherwise provided to the image processing module 218. The image processing module 218 may include any suitable combination of hardware, firmware, and software configured, adapted, or otherwise operable to process the image data provided by the ultrasonic sensor array 212. In some implementations, the image processing module 218 may include signal or image processing circuitry or circuit components, including, for example, amplifiers (such as instrumentation amplifiers or buffer amplifiers), analog or digital mixers or multipliers, switches, analog-to-digital converters (ADCs), passive filters, or active analog filters. In some implementations, one or more of such circuitry or circuit components may be integrated within a controller 214, for example, where the controller 214 is implemented as a system-on-a-chip (SoC) or a system-in-package (SIP). In some implementations, one or more of such circuitry or circuit components may be integrated within a DSP included in or coupled to the controller 214. In some implementations, the image processing module 218 may be implemented at least partially via software. For example, one or more functions of one or more of the circuits or circuit components just described, or the operations performed thereby, may instead be performed by one or more software modules, such as those executing in the processing unit of the controller 214 (e.g., in a general-purpose processor or DSP). In some implementations, the image processing module 218, or a portion thereof, may be implemented in software that can run on an application processor, such as processor 220 associated with the mobile device 210. The application processor may have a dedicated coprocessor and / or software modules (sometimes referred to as a “trust zone”) for securely processing biometric image data within that application processor.

[0057] In some implementations, in addition to the ultrasonic sensing system 200, the mobile device 210 may include a separate processor 220, memory 222, interface 216, and power supply 224. In some implementations, the controller 214 of the ultrasonic sensing system 200 may control the ultrasonic sensor array 212 and image processing module 218, and the processor 220 of the mobile device 210 may control other components of the mobile device 210. In some implementations, the processor 220 communicates data (including, for example, instructions or commands) to the controller 214. In some such implementations, the controller 214 may communicate data to the processor 220, including, for example, raw or processed image data (also referred to as "image information"). It should also be understood that in some other implementations, the functionality of the controller 214 may be wholly or at least partially implemented by the processor 220. In some such implementations, a separate controller 214 for the ultrasonic sensing system 200 may not be necessary, as the functionality of the controller 214 can be performed by the processor 220 of the mobile device 210.

[0058] Depending on the implementation, one or both of controller 214 and processor 220 may store data in memory 222. For example, the data stored in memory 222 may include raw measured image data, filtered or otherwise processed image data, estimated image data, or final refined image data. Memory 222 may store processor-executable code or other executable computer-readable instructions that can be performed by one or both of controller 214 and processor 220 to perform various operations (or cause other components (such as the ultrasonic sensor array 212, image processing module 218, or other modules) to perform operations) (including the operations, calculations, estimations, or other determinations described herein). It should also be understood that memory 222 may be collectively referred to as one or more memory devices (or “components”). For example, depending on the implementation, controller 214 may access data in a memory device different from processor 220 and store data in a memory device different from processor 120. In some implementations, one or more of the memory components may be implemented as NOR (or NAND) based flash memory arrays. In some other implementations, one or more of the memory components may be implemented as different types of non-volatile memory. Additionally, in some implementations, one or more of the memory components may include an array of volatile memory, such as, for example, RAM.

[0059] In some implementations, controller 214 or processor 220 may communicate data stored in memory 222 or data received directly from image processing module 218 via interface 216. For example, such communicated data may include image data or data derived from or otherwise determined from that image data. Interface 216 may be collectively referred to as one or more interfaces of various different types. In some implementations, interface 216 may include a memory interface for receiving data from external memory (such as a removable memory device) or storing data in external memory. Additionally or alternatively, interface 216 may include one or more wireless network interfaces or one or more wired network interfaces capable of transmitting raw or processed data to and from external computing devices, systems, or servers.

[0060] Power source 224 can provide power to some or all of the components in mobile device 210. Power source 224 may include one or more of a variety of energy storage devices. For example, power source 224 may include a rechargeable battery, such as a nickel-cadmium battery or a lithium-ion battery. Additionally or alternatively, power source 224 may include one or more supercapacitors. In some implementations, power source 224 may be rechargeable (or rechargeable) using power from, for example, a wall socket (or "socket") or a photovoltaic device (or "solar cell" or "solar cell array") integrated with mobile device 210. Additionally or alternatively, power source 224 may be wirelessly rechargeable. Power source 224 may include a power management integrated circuit and a power management system.

[0061] As used herein, the term "processing unit" refers to any combination of one or more of the following: the controller of the ultrasound system (e.g., controller 214), the image processing module (e.g., image processing module 218), or a separate processor (e.g., processor 220) of the device including the ultrasound system. In other words, the operations described below that are performed by or using the processing unit can be performed by one or more of the controller of the ultrasound system, the image processing module, or a separate processor of the device including the ultrasound sensing system.

[0062] Figure 3A A cross-sectional projection diagram of a portion of an example ultrasonic sensing system 300 according to some implementation is shown. Figure 3B It shows some implementations Figure 3A An enlarged cross-sectional side view of an example ultrasonic sensing system 300. For example, the ultrasonic sensing system 300 can realize a reference... Figure 1 The ultrasonic sensing system 118 described or referenced Figure 2A and Figure 2BAn ultrasonic sensing system 200 is shown and described. The ultrasonic sensing system 300 may include an ultrasonic transducer 302 that covers a substrate 304 and is located beneath a pressure plate (e.g., a "cover plate" or "cover glass") 306. The ultrasonic transducer 302 may include one or both of an ultrasonic transmitter 308 and an ultrasonic receiver 310.

[0063] The ultrasonic transmitter 308 is generally configured to generate and emit ultrasonic waves toward the pressure plate 306, and in the illustrated implementation, to emit ultrasonic waves toward a human finger 312 located on the upper surface of the pressure plate 306. In some implementations, the ultrasonic transmitter 308 may be more specifically configured to generate and emit ultrasonic surface waves toward the pressure plate 306. For example, the piezoelectric material of the ultrasonic transmitter 308 may be configured to convert an electrical signal provided by the controller of the ultrasonic sensing system into a continuous or pulsed sequence of ultrasonic surface waves at a scanning frequency. In some implementations, the ultrasonic transmitter 308 includes a piezoelectric material layer, such as, for example, polyvinylidene fluoride (PVDF) or PVDF copolymers (such as PVDF-TrFE). In some implementations, other piezoelectric materials, such as aluminum nitride (AlN), lead zirconate titanate (PZT), or sodium bismuth titanate, may be used in the ultrasonic transmitter 308 and / or the ultrasonic receiver 310. In some implementations, the ultrasonic transmitter 308 and / or ultrasonic receiver 310 may additionally or alternatively include capacitive ultrasonic devices, such as capacitive microcomputer ultrasonic transducers (CMUTs), or piezoelectric ultrasonic devices, such as piezoelectric microcomputer ultrasonic transducers (PMUTs, also known as "piezoelectric microcomputer ultrasonic transducers").

[0064] The ultrasound receiver 310 is generally configured to detect ultrasound reflections 314 arising from the interaction of ultrasound waves emitted by the ultrasound transmitter 308 with the ridges 316 and valleys 318 of the fingerprint defining the finger 312 being scanned. In some implementations, the ultrasound transmitter 308 covers the ultrasound receiver 310, such as in… Figure 3A and 3B As explained in the text. In some implementations, the ultrasound receiver 310 may cover the ultrasound transmitter 308 (as described below). Figure 4A(As shown in the diagram). The ultrasonic receiver 310 can be configured to generate and output an electrical output signal corresponding to detected ultrasonic reflections. In some implementations, the ultrasonic receiver 310 may include a second piezoelectric layer different from the piezoelectric layer of the ultrasonic transmitter 308. For example, the piezoelectric material of the ultrasonic receiver 310 can be any suitable piezoelectric material, such as, for example, a PVCF layer or a PVDF-TrFE copolymer. The piezoelectric layer of the ultrasonic receiver 310 can convert vibrations caused by ultrasonic reflections into an electrical output signal. In some implementations, the ultrasonic receiver 310 further includes a thin-film transistor (TFT) layer. In some such implementations, the TFT layer may include a sensor pixel circuit array configured to amplify or buffer the electrical output signal generated by the piezoelectric layer of the ultrasonic receiver 310. The electrical output signal provided by the sensor pixel circuit array can then be provided as raw measured image data to a processing unit for use in processing image data, identifying fingerprints associated with image data, and authenticating fingerprint-associated users in some applications. In some implementations, a single piezoelectric layer can act as both the ultrasonic transmitter 308 and the ultrasonic receiver 310 (as described below). Figure 4B As shown in the diagram, and referred to hereinafter as an ultrasonic transceiver. In some implementations, substrate 304 may be a glass, plastic, or silicon substrate on which electronic circuitry can be fabricated. In some implementations, the sensor pixel circuitry array and associated interface circuitry of ultrasonic receiver 310 may be configured by a CMOS circuitry formed in or on substrate 304. In some implementations, substrate 304 may be positioned between pressure plate 306 and ultrasonic transmitter 308 and / or ultrasonic receiver 310. In some implementations, substrate 304 may serve as pressure plate 306. One or more protective layers, acoustic matching layers, acoustic impedance layers, antifouling layers, adhesive layers, decorative layers, conductive layers, non-conductive layers, or coatings (not shown) may be included on one or both sides of substrate 304 and pressure plate 306.

[0065] The pressure plate 306 can be formed of any suitable material that can acoustically couple with the ultrasonic transmitter 308. For example, the pressure plate 306 can be formed of one or more of glass, plastic, ceramic, sapphire, metal, or metal alloy. In some implementations, the pressure plate 306 can be a cover plate, such as, for example, the cover glass or lens glass of a bottom display. In some implementations, the pressure plate 306 can comprise one or more polymers (such as one or more types of parylene) and can be significantly thinner. In some implementations, the pressure plate 306 can have a thickness ranging from about 10 micrometers (μm) to about 1000 μm or greater.

[0066] In some implementations, the ultrasonic sensing system 300 may further include a focusing layer (not shown). For example, the focusing layer may be positioned above the ultrasonic transmitter 308. The focusing layer may generally include one or more acoustic lenses capable of altering the path of the ultrasonic waves emitted by the ultrasonic transmitter 308. In some implementations, the lenses may be cylindrical lenses, spherical lenses, or zone lenses. In some implementations, some or all of these lenses may be concave lenses, while in other implementations, some or all of these lenses may be convex lenses, or a combination of concave and convex lenses.

[0067] In some implementations that include such a focusing layer, the ultrasonic sensing system 300 may additionally include an acoustic matching layer to ensure proper acoustic coupling between the focusing lens and an object, such as a finger located on the pressure plate 306. For example, the acoustic matching layer may comprise an epoxy resin doped with particles that alter the density of the acoustic matching layer. With the sound velocity remaining constant, if the density of the acoustic matching layer is changed, the acoustic impedance will also change accordingly. In alternative implementations, the acoustic matching layer may comprise silicone rubber doped with metal or ceramic powder. In some implementations, a sampling strategy for processing the output signal can be implemented that takes advantage of the reflection of ultrasound received through the lens of the focusing layer. For example, ultrasound returning from the lens focus will travel into the lens and, satisfying the principle of acoustic reciprocity, can propagate toward multiple receiver elements in a receiver array. Depending on the signal strength returned from the scattered field, the number of active receiver elements can be adjusted. Generally, the more receiver elements activated to receive the returning ultrasound, the higher the signal-to-noise ratio (SNR). In some implementations, with or without a focusing layer, one or more acoustic matching layers may be placed on one or both sides of the pressure plate 306.

[0068] Figure 4A It shows some implementations Figure 3A and 3B An exploded projection view of an example component of an example ultrasonic sensing system 300. The ultrasonic transmitter 308 may include a substantially planar piezoelectric transmitter layer 422 capable of serving as a plane wave generator. Ultrasonic waves can be generated by applying a voltage across the piezoelectric transmitter layer 422, causing the layer to expand or contract depending on the applied voltage signal, thereby generating a plane wave. In this example, a processing unit (not shown) is capable of causing a transmitter excitation voltage to be applied across the piezoelectric transmitter layer 422 via a first transmitter electrode 424 and a second transmitter electrode 426. The first and second transmitter electrodes 424 and 426 may be metallized electrodes, for example, metal layers covering opposite sides of the piezoelectric transmitter layer 422. As a result of the piezoelectric effect, the applied transmitter excitation voltage causes a change in the thickness of the piezoelectric transmitter layer 422, and in this way, ultrasonic waves are generated at the frequency of the transmitter excitation voltage.

[0069] Ultrasonic waves can travel towards a target object (such as a finger) through pressure plate 306. A portion of the ultrasonic wave that is not absorbed or emitted by the target object can be reflected back through pressure plate 306 and received by ultrasonic receiver 310. Figure 4A In the described implementation, an ultrasonic receiver 310 covers an ultrasonic transmitter 308. The ultrasonic receiver 310 may include an array of sensor pixel circuits 432 and a piezoelectric receiver layer 436 disposed on a substrate 434. In some implementations, each sensor pixel circuit 432 may include one or more TFT-based or silicon-based CMOS transistor elements, electrical interconnect traces, and in some implementations, one or more additional circuit elements, such as diodes, capacitors, etc. Each sensor pixel circuit 432 may be configured to convert surface charges generated in the piezoelectric receiver layer 436 adjacent to the pixel circuit into electrical signals. Each sensor pixel circuit 432 may include a pixel input electrode 438 electrically coupling the piezoelectric receiver layer 436 to the sensor pixel circuit 432.

[0070] In the described implementation, a receiver bias electrode 440 is disposed on the side of the piezoelectric receiver layer 436 adjacent to the pressure plate 306. The receiver bias electrode 440 may be a metallized electrode and may be grounded or biased to control which signals can be transmitted to the array of sensor pixel circuits 432. Ultrasonic energy reflected from the exposed (upper / top) surface of the pressure plate 306 can be converted into surface charge by the piezoelectric receiver layer 436. The generated surface charge can be coupled to the pixel input electrode 438 and the underlying sensor pixel circuit 432. The charge signal can be amplified or buffered by the sensor pixel circuit 432 and provided to the processing unit. The processing unit may be electrically connected (directly or indirectly) to the first transmitter electrode 424 and the second transmitter electrode 426, and to the receiver bias electrode 440 and the sensor pixel circuit 432 on the substrate 434. In some implementations, the processing unit may operate substantially as described above. For example, the processing unit may be able to process signals received from the sensor pixel circuit 432.

[0071] Some examples of suitable piezoelectric materials that can be used to form the piezoelectric emitter layer 422 or the piezoelectric receiver layer 436 include piezoelectric polymers with appropriate acoustic properties (e.g., acoustic impedance between about 2.5 Mrayl and 5 Mnayl). Specific examples of piezoelectric materials that can be used include ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymers. Examples of PVDF copolymers include 60:40 (molar percentage) PVDF-TrFE, 70:30 PVDF-TrFE, 80:20 PVDF-TrFE, and 90:10 PVDR-TrFE. Other examples of available piezoelectric materials include polyvinylidene chloride (PVDC) homopolymers and copolymers, polytetrafluoroethylene (PTFE) homopolymers and copolymers, and diisopropylammonium bromide (DIPAB). In some implementations, other piezoelectric materials, such as aluminum nitride (AlN), lead zirconate titanate (PZT), or sodium bismuth titanate, may be used in the piezoelectric emitter layer 422 and / or the piezoelectric receiver layer 436.

[0072] The thickness of each of the piezoelectric transmitter layer 422 and the piezoelectric receiver layer 436 is selected to suit the generation and reception of ultrasonic waves, respectively. In some implementations, the thickness of each is between about 5 μm and about 30 μm, or between about 5 μm and about 15 μm. In one example, the PVDF piezoelectric transmitter layer 422 is about 28 μm thick, and the PVDF-TrFE receiver layer 436 is about 12 μm thick. Example frequencies of ultrasonic waves can range from about 1 MHz to about 100 MHz, where the wavelength is on the order of millimeters or smaller.

[0073] Figure 4B It shows some implementations Figure 3A and 3B An exploded projection view of an example component of an ultrasonic transceiver array in an ultrasonic sensing system 300. In this example, the ultrasonic sensing system 300 includes an ultrasonic transceiver array 450 beneath a pressure plate 306. The ultrasonic transceiver array 450 can be used as... Figure 2BAn ultrasonic sensor array 212 is shown and described above. An ultrasonic transceiver array 450 may include a substantially planar piezoelectric transceiver layer 456 capable of serving as a plane wave generator. Ultrasonic waves can be generated by applying a voltage across the transceiver layer 456. A control system 204 may be able to generate a transceiver excitation voltage that can be applied across the piezoelectric transceiver layer 456 via one or more of the lower pixel input electrodes 438 or one or more of the upper transceiver bias electrodes 460. The generated ultrasonic waves can travel toward a finger or other object to be detected, passing through a pressure plate 306. A portion of the wave that is not absorbed or transmitted by the object can be reflected back through the pressure plate 306 and received by the ultrasonic transceiver array 450. The ultrasonic transceiver array 450 can be used as both an ultrasonic transmitter and an ultrasonic receiver using a single piezoelectric transceiver layer 456.

[0074] The ultrasonic transceiver array 450 may include an array of sensor pixel circuits 432 disposed on a sensor substrate 434. In some implementations, each sensor pixel circuit 432 may include one or more TFT-based or silicon-based elements, electrical interconnect traces, and in some implementations, one or more additional circuit elements, such as diodes, capacitors, etc. Each sensor pixel circuit 432 may include a pixel input electrode 438 electrically coupling the piezoelectric transceiver layer 456 to the sensor pixel circuit 432.

[0075] In the described implementation, transceiver bias electrode 460 is arranged on the side of piezoelectric transceiver layer 456 adjacent to pressure plate 306. Transceiver bias electrode 460 may be a metallized electrode and may be grounded or biased to control which signals are generated and which reflected signals are transmitted to the array of sensor pixel circuits 432. Ultrasonic energy reflected from the exposed (top) surface 442 of pressure plate 306 can be converted into surface charge by piezoelectric transceiver layer 456. The generated surface charge can be coupled to pixel input electrode 438 and the underlying sensor pixel circuit 432. The charge signal can be amplified or buffered by sensor pixel circuit 432 and provided to control system 204.

[0076] The control system 204 may be electrically connected (directly or indirectly) to the transceiver bias electrode 460 and the sensor pixel circuit 432 on the sensor substrate 434. In some implementations, the control system 204 may operate substantially as described above. For example, the control system 204 may be able to process amplified or buffered electrical output signals received from the sensor pixel circuit 432.

[0077] The control system 204 may be able to control the ultrasonic transceiver array 450 to acquire ultrasonic image data, which may include fingerprint image data. Depending on some implementations, the control system 204 may be able to provide functionality such as that described herein, for example, as referenced herein. Figure 1 , 2A The functionality described in -2B, 3A-3B, 4A-4B, 5-7, 9-10, 11A-11C, 12A-12B and 13A-13B.

[0078] In other examples of ultrasonic sensor systems with an ultrasonic transceiver array, the back side of the sensor substrate 434 may be directly or indirectly attached to the pressure plate 306 above it. In operation, ultrasonic waves generated by the piezoelectric transceiver layer 456 can travel through the sensor substrate 434 and the pressure plate 306, be reflected by the surface 442 of the pressure plate 306, and return to travel through the pressure plate 306 and the sensor substrate 434 before being detected by the sensor pixel circuit 432 on or in the substrate sensor 434.

[0079] Many electronic devices, including mobile devices and smartphones, use fingerprint authentication as a method of access control. An ultrasonic fingerprint sensor authenticates a user's fingerprint, where ultrasonic waves generated by a piezoelectric material travel through a pressure plate on which the finger rests. Some portions of the ultrasonic waves encounter the skin in contact with the pressure plate, such as the ridges of the fingerprint, while other portions encounter air, such as the valleys between the ridges. The ultrasonic waves are reflected back towards an array of ultrasonic sensors at varying intensities. The reflected signals associated with the finger can be processed and converted into digital values ​​representing the signal strength of the reflected signals, thus obtaining a fingerprint image.

[0080] Figure 5 A cross-sectional view of an example underplate ultrasonic sensor system with flexible printed circuit (FPC) is shown. Figure 5 In this embodiment, the ultrasonic sensor system 500 is located below or beneath the pressure plate 510. The pressure plate 510 can be considered as being "in front of," "above," or "covering" the ultrasonic sensor system 500, and the ultrasonic sensor system 500 can be considered as being "behind," "below," or "under" the pressure plate 510. Such terms, as used herein, are relative terms depending on the orientation of the device. In some implementations, the ultrasonic sensor system 500 is coupled to the pressure plate 510 via a first adhesive 560. A finger 505 presses against the pressure plate 510 to activate the ultrasonic sensor system 500. In some implementations, the pressure plate 510 can be a cover glass of a display device (e.g., a mobile device). In some implementations, the pressure plate 510 can include part of a display (such as an organic light-emitting diode (OLED) or an active-matrix organic light-emitting diode (AMOLED) display).

[0081] The ultrasonic sensor system 500 may include a sensor substrate 540, a plurality of sensor circuits 545 disposed on the sensor substrate 540, a transceiver layer 520, and an electrode layer 515. The transceiver layer 520 may be referred to as a "piezoelectric layer" or a "piezoelectric transceiver layer." The electrode layer 515 may be referred to as a "transceiver electrode layer." In some implementations, the transceiver layer 520 may correspond to... Figure 4B The piezoelectric transceiver layer 456, or may correspond to Figure 4A The ultrasonic sensor system 500 may further include one or both of the piezoelectric receiver layer 436 and the piezoelectric emitter layer 422. Different implementations may use different materials for the sensor substrate 540. For example, the sensor substrate 540 may include a silicon substrate, a silicon-on-insulator (SOI) substrate, a thin-film transistor (TFT) substrate, a glass substrate, a plastic substrate, a ceramic substrate, and / or combinations thereof.

[0082] Multiple sensor circuits 545 may be formed on or above the sensor substrate 540, such as TFT circuits formed on a TFT substrate or complementary metal-oxide-semiconductor (CMOS) circuits formed on or in a silicon substrate. In some implementations, a transceiver layer 520 may be positioned above the multiple sensor circuits 545. The transceiver layer 520 may function as both a transmitter and a receiver of ultrasonic waves, wherein the transceiver layer 520 is configured to transmit at least one ultrasonic wave / signal and to receive or detect at least one ultrasonic wave / signal. Accordingly, the transceiver layer 520 may include one or more piezoelectric layers and one or more electrode layers to enable the transceiver layer to transmit and receive ultrasonic waves.

[0083] Ultrasound is a sound wave with a frequency higher than approximately 20 kHz. In some implementations, ultrasound has frequencies between approximately 1 MHz and approximately 100 MHz, such as between approximately 5 MHz and approximately 20 MHz. A sound wave is a longitudinal wave with a vibration direction in the same direction as its travel. Sound waves propel particles in a medium, regardless of whether the medium is solid, liquid, or gas. Sound waves travel at the speed of sound, which depends on the medium they pass through. Acoustic impedance in a material is measured against the acoustic flow generated by the sound pressure applied to that material. Acoustic impedance enables the determination of the reflection and transmission of sound energy at boundaries. If the acoustic impedances of two media are very different, most of the sound energy will be reflected rather than transmitted across the boundary. Acoustic impedance can be expressed in Pascals per second per meter (Pa-s / m or kg / s / m). 2 It is measured in Rayleigh or MegaRayl.

[0084] Multiple sensor circuits 545 may include an array of thin-film transistor circuits. For example, sensor circuits 545 may include an array of pixel circuits, wherein each pixel circuit may include one or more TFTs. Pixel circuits may be configured to convert charges generated in a transceiver layer adjacent to the pixel circuit into electrical signals in response to received ultrasonic waves. Output signals from sensor circuits 545 may be sent to a controller or other circuitry for signal processing.

[0085] In some implementations, transceiver electrode layer 515 may be disposed, positioned, placed, or formed above transceiver layer 520. Transceiver electrode layer 515 may include one or more conductive layers / traces coupled to transceiver layer 520. In some implementations, transceiver electrode layer 515 may include silver ink. In some implementations, transceiver electrode layer 515 may include copper, aluminum, nickel, or combinations thereof. Ultrasonic waves can be generated and emitted by providing electrical signals to transceiver electrode layer 515. Additionally, a passivation layer (not shown) may be disposed, positioned, placed, or formed above at least some portions of transceiver electrode layer 515. The passivation layer may include one or more electrically insulating material layers. Sensor substrate 540 and sensor circuitry 545, piezoelectric transceiver layer 520, and transceiver electrode layer 515 may be positioned below pressure plate 510.

[0086] Figure 5 A flexible printed circuit (FPC) 525 coupled to a sensor substrate 540 is shown. However, it will be understood that in this disclosure, the sensor substrate 540 may be coupled to a rigid printed circuit board (PCB) or other circuit system. The FPC 525 may be referred to as a flexible strip, flexible cable, flexible circuit, or simply as a “flexible element.” The FPC 525 may include one or more dielectric layers and one or more interconnects (e.g., traces, vias, and pads). In some implementations, the FPC 525 may be electrically coupled to a controller or other circuit system for signal processing of signals going to / from the sensor circuit 545. In some implementations, the FPC 525 may wrap around from the front side to the rear side of the ultrasonic sensor system 500.

[0087] exist Figure 5In this embodiment, the ultrasonic sensor system 500 can be attached to the pressure plate 510 using a first adhesive 560 and an edge sealant 555. The ultrasonic sensor system 500 may further include a sensor housing or cap 530 for protecting the ultrasonic sensor system 500. The sensor housing 530 may be coupled to a portion of the pressure plate 510 via a second adhesive 565 and to a portion of the sensor substrate 540 and a portion of the FPC 525 via a third adhesive 550. In some implementations, the sensor housing 530 may be substantially suspended above the active region of the sensor substrate 540. The sensor housing 530 may be coupled to the sensor substrate 540 such that a cavity 535 is formed between the back side of the sensor substrate 540 and the sensor housing 530. In some implementations, the sensor housing 530 may include one or more layers of plastic or metal. In some implementations, the sensor housing 530 and the cavity 535 may allow the interface between the sensor substrate 540 and the cavity 535 to function as an acoustic barrier for the ultrasonic sensor system 500. In some implementations, cavity 535 may provide space for a tolerant acoustic shielding structure configured to absorb, trap, or otherwise attenuate ultrasonic waves. FPC 525 may surround sensor substrate 540 and sensor housing 530, wherein FPC 525 is attached to the back side of sensor housing 530.

[0088] The ultrasonic sensor system 500 under the pressure plate can be provided in, for example Figure 5 In the display device shown, the under-plate ultrasonic sensor system 500 may be located in a discrete, localized area of ​​the display device, wherein the under-plate ultrasonic sensor system 500 may be located in a bezel, boundary, or other area outside the display area of ​​the display device. The use of a display device with an under-plate ultrasonic sensor system or at least one ultrasonic sensor system not located under the display is described in [the context of the image]. Figure 6 As shown in the figure. In contrast, the under-display ultrasonic sensor system can be provided in a different display device than the under-plate ultrasonic sensor system. An example membrane stack and construction of the under-display ultrasonic sensor system 995 is shown in... Figure 9 As shown, the example membrane stacking and construction of the ultrasonic sensor system 500 under the pressure plate are illustrated. Figure 5 As shown in the diagram. Accordingly, the display device including the under-display ultrasonic sensor system can be constructed differently from the under-plate ultrasonic sensor system. The use of a display device with an under-display ultrasonic sensor system in Figure 7-8 As shown in the image.

[0089] Figure 6 An example of using a fingerprint sensor when it is not located under the display is shown. Figure 6 In this context, display device 605 (e.g., mobile device 210) includes operable sensor 625 (e.g., Figure 5The controller circuit of the ultrasonic sensor system 500 (e.g., Figure 2B (Controller 214 in the controller). In some implementations, the controller circuitry can switch sensor 625 between a capacitive sensing mode and an ultrasonic sensing mode. For example, sensor 625 may be configured in capacitive sensing mode to determine whether an object is touching or near the receiver bias electrode of the ultrasonic sensor, and then subsequently configured in ultrasonic sensing mode to determine whether the object is a finger 615.

[0090] like Figure 6 As shown, at time 650, finger 615 is placed over sensor 625, which is part of an ultrasonic authentication button (e.g., a "home button") on display device 605. In some implementations, sensor 625 may be part of an electromechanical button capable of authenticating the user and inserted into the cover glass of display 610 by cutting a separate area. Accordingly, sensor 625 may be placed in a location separate from the area on display 610 where visual image content is displayed. At time 650, display device 605 may be locked, turned off, or in a relatively low-power "sleep" mode. An object or finger 615 may be determined to have been placed near or on display 610, sensor 625, or other sensing electrodes. Then at time 655, if the fingerprint of finger 615 is authenticated, controller circuitry may "wake up" application processor and cause display 610 to turn on. For example, application processor may obtain fingerprint image data (e.g., by receiving corresponding data stored in memory by controller circuitry) and then determine whether the fingerprint image data represents the fingerprint of an authorized user of display device 605. Image data of the authorized fingerprint may have been previously provided by the user (e.g., the owner), for example, during setup of display device 605 or during registration and security feature setup of display device 605.

[0091] Figure 7 Examples of fingerprint sensor usage with the fingerprint sensor located under the display are shown, based on some implementations. A fingerprint sensor located under the display is also considered a fingerprint sensor within the display. Figure 7 In the display device 705 (e.g., mobile device 210), an operable sensor 725 (e.g., Figure 9 The controller circuit of the ultrasonic sensor system 995 (e.g., Figure 2B The controller 214 (in the display) and sensor 625 are located in the cut-out area of ​​the cover glass of the display 610. Figure 6 To create a contrast, Figure 7The sensor 725 is placed in the area of ​​the display 710 through which visual image content is displayed. Placing the sensor 725 in the display area of ​​the display 710 can improve the user interface and increase the functionality of the display 710 of the display device 705. The sensor 725 can be located in a localized, fixed area of ​​the display 710 to perform fingerprint scanning. When the application processor, for example, determines that the acquired fingerprint image data represents the fingerprint of an authorized user of the display device 705, the controller circuitry can "wake up" the display 710 of the display device 705. The sensor 725 does not necessarily need to be as described above. Figure 6 This is part of the electromechanical button discussed herein. Accordingly, when a finger 715 is placed near or on the sensor 725, the sensor 725 can authenticate the user's fingerprint. The sensor 725 can authenticate the user's fingerprint using an ultrasonic fingerprint sensor system as described herein.

[0092] Figure 8 Images of example display devices, based on some implementations, are shown where the fingerprint sensor is located below the display and spans the entire display area. Figure 8 In this context, the display device 805 (e.g., mobile device 210) includes a controller circuit for an operable sensor 825 (e.g., any of the ultrasonic sensor systems shown in Figures 10-15C). Figure 2B The controller 214 in the middle. The fingerprint sensors 625 and 725 are placed in a localized, fixed area. Figure 6-7 To create a contrast, Figure 8 The sensor 825 and its active area can be extended to the entire area of ​​the display 810 of the display device. This allows the display device 805 to authenticate a user's fingerprint from any location on the display 810. When the application processor, for example, determines that the acquired fingerprint image data represents the fingerprint of an authorized user of the display device 805, the controller circuitry can "wake up" the display 810 of the display device 805. The sensor 825 does not need to be as described above. Figure 6 This is part of the electromechanical button discussed herein. In some implementations, sensor 825 is an ultrasonic sensor. As used herein, ultrasonic sensor may refer to an ultrasonic fingerprint sensor, an ultrasonic fingerprint sensor system, an ultrasonic sensor system, or an array of ultrasonic sensors that is not limited to fingerprint sensing but may include sensing of other user attributes such as palm prints and fingerprints.

[0093] Advances in user authentication technology have led to a growing demand for improved security, performance, and user experience. Implementing ultrasonic fingerprint sensors outside the localized, discrete area of ​​the display enhances security, performance, and user experience. A larger active sensor area allows for additional matching criteria used for user authentication. For example, a user can be further authenticated by matching a fingerprint scan with additional fingerprint scans of additional fingers, palm prints, and / or fingerprints. Multi-finger authentication, palm print authentication, and / or fingerprint authentication provide an additional layer of security and improved biometric performance to minimize false positives and false negatives. Furthermore, a larger active sensor area allows a user's finger, palm, hand, or other appendages to be placed anywhere on the display area, making precise placement in a precise location unnecessary. Continuous authentication from any location on the display enhances the user experience.

[0094] Figure 9 A cross-sectional schematic diagram of an example display device including an ultrasonic fingerprint sensor system under the display, according to some implementations, is shown. Figure 9 The acoustic path of ultrasound waves from an ultrasonic fingerprint sensor system through a display, according to some implementations, is also illustrated. As described above, the ultrasonic fingerprint sensor system 995 may include a sensor substrate 970, which includes a plurality of sensor circuits 972. The ultrasonic fingerprint sensor system 995 may further include a piezoelectric layer 980 coupled to the sensor substrate 970 and an electrode layer 985 coupled to the piezoelectric layer 980. In some implementations, the ultrasonic fingerprint sensor system 995 may optionally include a passivation layer 990. Printed circuitry 975 (e.g., flexible printed circuitry) or other circuitry may be coupled to the sensor substrate 970 and may be electrically coupled to one or more sensor circuits 972. In some implementations, the piezoelectric layer 980 and the electrode layer 985 are part of an ultrasonic transceiver configured to transmit and receive ultrasound waves. It will be appreciated that in some implementations, the ultrasonic transmitter and receiver functions may be divided into a discrete piezoelectric receiver layer with an electrode receiver layer and a discrete piezoelectric transmitter layer with an electrode transmitter layer. Examples of ultrasonic sensor systems with separate ultrasonic transmitters and ultrasonic receivers are shown in Figures 14A-14C As shown in 15A-15C.

[0095] An ultrasonic fingerprint sensor system 995 can be configured to emit and receive ultrasonic waves traveling in an acoustic path 950 through a display 965 of a display device 900, wherein the ultrasonic fingerprint sensor system 995 is located below the display 965 of the display device 900. The display 965 may include multiple thin-film layers, some of which may comprise organic or plastic materials. The display 965 may include a DMS-based display, an LED display, an OLED display, an LCD, a plasma display, an IMOD-based display, or another type of display suitable for use with a touch-sensitive user interface. For example, the display 965 is an OLED display with multiple thin-film layers. The display 965 may include multiple pixels arranged in a matrix. At least some of the ultrasonic waves emitted from the ultrasonic fingerprint sensor system 995 may be reflected back by an object 930 (e.g., a finger) located on the outer surface of the display 965, the touchscreen, the cover glass, the cover plate, or the pressure plate 905. The acoustic path 950 can be defined by the propagation of ultrasonic waves to and from the ultrasonic fingerprint sensor system 995, which allows an object 930 (such as a finger placed in contact with the outer surface of the display 965 or the outer surface of the pressure plate 905) to be imaged. To integrate the display 965 and the underlying ultrasonic fingerprint sensor system 995, a multifunctional membrane 955 can be placed between the ultrasonic fingerprint sensor system 995 and the display 965 such that the multifunctional membrane 955 is within the acoustic path 950. In some implementations, the multifunctional membrane 955 includes one or more of a light-blocking layer, an electrical shielding layer, an adhesive layer, and a mechanical pressure isolation layer, one or more of which are within the acoustic path 950. Details relating to the multifunctional membrane 955 and the integration of the ultrasonic fingerprint sensor system 995 with the display 965 are described in U.S. Patent Application No. 16,006,640, filed June 12, 2018, entitled “ULTRASONICFINGERPRINT SENSOR FOR UNDER-DISPLAY APPLICATIONS,” which is incorporated herein by reference in its entirety for all purposes. In some implementations, the multifunctional membrane 955 may include an adhesive layer, which may be a pressure-sensitive adhesive or an epoxy resin. In some implementations, the multifunctional membrane 955 may include a spacer layer, which may be an elastic material such as polyethylene terephthalate (PET), wherein the spacer layer is provided as an addition to or replacement of the adhesive layer.

[0096] In some implementations, the sensor substrate 970 is placed in the acoustic path 950. In such implementations, the sensor substrate 970 is attached to the display 965 via a multifunctional film 955, with a piezoelectric layer 980 below the sensor substrate 970, an electrode layer 985 below the piezoelectric layer 985, and a passivation layer 990 below the electrode layer 985. In such implementations, the sensor substrate 970 can be a rigid substrate, such as a glass substrate. The rigid substrate provides protection for the ultrasonic fingerprint sensor and acoustic coupling with it. As a result, ultrasonic waves can be propagated and reflected through the display without distorting the fingerprint image. However, rigid substrates such as glass substrates may be prone to breakage or other physical damage when manufactured into large-area substrates. For example, manufacturing on large-area sensors (such as 30mm x 20mm, 60mm x 40mm, 70mm x 150mm) or other large-area (e.g., the entire display area) dimensions can lead to the breakage of the glass substrate, especially during manufacturing operations such as lamination. This manufacturing difficulty negatively impacts throughput and reliability.

[0097] In some implementations, the sensor substrate 970 is not placed in the acoustic path 950. In such implementations, the electrode layer 985 is attached to the display 965 via a multifunctional film 955, the piezoelectric layer 980 is below the electrode layer 985, and the sensor substrate 970 is below the piezoelectric layer 980. In such implementations, the sensor substrate 970 can be a flexible substrate, such as a plastic substrate. Flexible substrates allow the fabrication of large-area ultrasonic fingerprint sensor systems to avoid or minimize the manufacturing difficulties associated with glass substrates. This increases the active sensor area of ​​the ultrasonic fingerprint sensor system in the display. Ultrasonic fingerprint sensor systems on flexible substrates also enable integration with flexible displays, curved displays, curved cover glass, and emerging 2.5D or 3D displays. However, replacing a glass substrate with a flexible substrate results in poorer acoustic coupling between the ultrasonic fingerprint sensor system and the display / plate. Specifically, due to the similar acoustic impedance values ​​between the flexible substrate and the piezoelectric transmitter / transceiver, a low acoustic pressure interface is created between the flexible substrate and the piezoelectric transmitter / transceiver. As a result, image quality and performance are degraded.

[0098] Providing a large-area ultrasonic fingerprint sensor system with a display presents numerous challenges. As mentioned above, combining a flexible substrate with a large-area ultrasonic fingerprint sensor system presents acoustic-related challenges. Additionally, the increased electrode size in a large-area ultrasonic fingerprint sensor system poses challenges in power management. The piezoelectric layer can bend, flex, or vibrate in response to a driving voltage applied to the electrodes to generate ultrasonic waves. For large-area ultrasonic sensors, the transmitter capacitance becomes significantly larger with the larger electrode area. The driving voltage used to drive the ultrasonic transmitter / transceiver used to generate ultrasonic waves becomes extremely high, on the order of hundreds of volts, for example, between approximately 100V and approximately 200V. Significantly high peak currents are required to provide such higher driving voltages, and it may be impossible to draw such available power from control circuitry (e.g., driver chip ASIC) with limited power handling capabilities, or at least result in significant power waste.

[0099] In some implementations, the electrodes coupled to or adjacent to the piezoelectric transmitter / transceiver used to generate ultrasound can be segmented into multiple electrode segments. Segmenting the electrodes into smaller segments reduces the driving voltage applied to a specific electrode segment. Instead of generating ultrasound across a continuous large electrode, ultrasound can be generated for a specific electrode segment among multiple segments. Those driven electrode segments can be those covering or beneath the object being imaged. Driving such specific electrode segments can also be referred to as a “frequency-modulated burst” or “frequency-modulated burst voltage.” Accordingly, by segmenting the electrodes into smaller segments, power consumption when imaging the object is reduced. However, segmenting the electrodes also introduces gaps between the electrode segments, which can introduce image distortion, image discontinuities, and other image artifacts when imaging the object.

[0100] Figures 10A-10C A schematic cross-sectional view of the respective electrode layers coupled to a piezoelectric layer configured to generate ultrasonic waves, according to some implementations, is shown. Generally, the electrode layers coupled to the piezoelectric layer are thick metal layers. The thick metal layer can be sufficiently thick and made of a suitable metal for acoustic coupling with an ultrasonic fingerprint sensor system. For example, the thick metal layer can have a thickness greater than about 5 μm, such as between about 10 μm and about 50 μm, and may include silver ink. However, forming a thick metal layer can result in larger gaps.

[0101] Figure 10AA cross-sectional schematic diagram of an ultrasonic transmitter / transceiver with silver ink electrodes is shown. The ultrasonic transmitter / transceiver 1000a includes a sensor substrate 1010 that may have multiple sensor circuits, a piezoelectric layer 1020 coupled to the sensor substrate 1010, and a thick silver ink electrode 1030 coupled to the piezoelectric layer 1020. The thick silver ink electrode 1030 is divided into multiple electrode segments. Forming the thick silver ink electrode 1030 can result in large gap distances between adjacent segments, such as greater than about 200 μm, greater than about 300 μm, or gap distances between about 300 μm and about 600 μm (e.g., 500 μm). In some implementations, the thickness of the thick silver ink electrode 1030 can be between about 10 μm and about 50 μm. During silver ink deposition, the silver ink can be screen-printed in two or more layers. As more layers of silver ink are added, the tolerance for alignment errors in screen printing becomes larger, thereby resulting in larger gaps / spaces between the electrode segments of the thick silver ink electrode 1030.

[0102] Figure 10B A schematic cross-sectional view of an ultrasonic transmitter / transceiver with silver ink electrodes and a non-conductive acoustic layer is shown. The ultrasonic transmitter / transceiver 1000b includes a sensor substrate 1010 capable of having multiple sensor circuits, a piezoelectric layer 1020 coupled to the sensor substrate 1010, a thin silver ink electrode 1040 coupled to the piezoelectric layer 1040, and a non-conductive acoustic layer 1060 disposed on the thin silver ink electrode 1040. The thin silver ink electrode 1040 is divided into multiple electrode segments. Forming the thin silver ink electrode 1040 can result in a higher density between adjacent segments. Figure 10A Smaller gap distances are achieved, where the gap distance can be between about 100 μm and about 500 μm, or between about 150 μm and about 400 μm (e.g., 200 μm). In some implementations, the thickness of the thin silver ink electrode 1040 can be between about 2 μm and about 20 μm. Having fewer silver ink layers does not lead to as many instances of alignment errors in screen printing, thereby resulting in smaller gaps / spaces between the electrode segments of the thin silver ink electrode 1040. Additionally, in Figure 10B The non-conductive acoustic layer 1060 is provided as a replacement. Figure 10A The acoustic-related functions of the thick silver ink electrode 1030 are described. The non-conductive acoustic layer 1060 has similar acoustic properties to the thick silver ink electrode 1030, enabling it to provide acoustic coupling with the ultrasonic fingerprint sensor system. As used herein, the term "non-conductive acoustic layer" may also be referred to as a "non-conductive high acoustic impedance layer" or a "non-conductive high density layer." Various aspects of the non-conductive acoustic layer are described in more detail below.

[0103] Figure 10CA cross-sectional schematic diagram of an ultrasonic transmitter / transceiver with thin metal electrodes and a non-conductive acoustic layer is shown. The ultrasonic transmitter / transceiver 1000c includes a sensor substrate 1010 capable of having multiple sensor circuits, a piezoelectric layer 1020 coupled to the sensor substrate 1010, thin metal electrodes 1050 coupled to the piezoelectric layer 1020, and a non-conductive acoustic layer 1060 disposed on the thin metal electrodes 1050. The thin metal electrodes 1050 are divided into multiple electrode segments. Forming the thin metal electrodes 1050 can result in a higher density between adjacent segments. Figure 10A and 10B Smaller gap distances are possible, ranging from approximately 25 μm to approximately 200 μm, or from approximately 50 μm to approximately 150 μm (e.g., 100 μm). The thin metal electrode 1050 can be deposited using any suitable deposition technique, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), or electroplating. In some implementations, the thickness of the thin metal electrode is between approximately 10 nm and approximately 2000 nm, or between approximately 20 nm and approximately 1000 nm. Additionally, in... Figure 10C The non-conductive acoustic layer 1060 is provided as a replacement. Figure 10A Acoustic-related functions of the medium-thickness silver-ink electrode 1030.

[0104] Segmented electrodes may be part of the ultrasonic fingerprint sensor system of this disclosure. In some implementations, the gap size between segmented electrodes can be reduced by employing a thick non-conductive acoustic layer adjacent to a thin conductive layer. In some implementations, the ultrasonic fingerprint sensor system includes a flexible substrate or a rigid substrate. In some implementations, the ultrasonic fingerprint sensor system includes an ultrasonic transceiver or an ultrasonic transmitter separate from the ultrasonic receiver. The film stacking used in the ultrasonic fingerprint sensor system varies depending on whether a flexible or rigid substrate is used, whether an ultrasonic transceiver or an ultrasonic transmitter separate from the ultrasonic receiver is used, and whether a thick metal layer or a thick non-conductive acoustic layer is used for the ultrasonic transmitter / transceiver. Figure 11A –11B, 12A–12B, 13A–13B, 14A–14C, and 15A–15C illustrate example film stacks for various implementations of an ultrasonic fingerprint sensor system attached to and beneath a display. It will be understood that… Figure 11A The arrangement and depiction of the membrane stacks in –11B, 12A–12B, 13A–13B, 14A–14C and 15A–15C are illustrative and non-limiting, and the implementation of the ultrasonic fingerprint sensor system is not intended to be limited to the examples described below.

[0105] Figure 11AA schematic cross-sectional view of an example ultrasonic fingerprint sensor system with a rigid substrate beneath a display, according to some implementations, is shown. The ultrasonic fingerprint sensor system 1110 includes a rigid substrate 1111 having multiple sensor circuits 1112. The ultrasonic fingerprint sensor system 1110 includes an ultrasonic transceiver 1113 coupled to the rigid substrate 1111, wherein the ultrasonic transceiver 1113 includes a piezoelectric layer 1114 coupled to the rigid substrate 1111 and an electrode layer 1115 coupled to the piezoelectric layer 1114. In some implementations, the electrode layer 1115 may be divided into multiple electrode segments. The electrode layer 1115 may include a thick metal layer, such as a thick silver ink electrode as described above. In some implementations, the ultrasonic fingerprint sensor system 1110 further includes a passivation layer 1116 covering the electrode layer 1115. The passivation layer 1116 may be used for electrical insulation and protection of the electrode layer 1115. In some implementations, the FPC (not shown) may be coupled to a rigid substrate 1111, wherein the FPC may include one or more dielectric layers and one or more interconnects (e.g., traces, vias, pads). The FPC may be electrically coupled to a controller or other circuitry for signal processing of signals to / from sensor circuitry 1112.

[0106] The rigid substrate 1111 can be attached to the display 1117 via adhesive 1118. A pressure plate, cover glass, cover plate, or outer layer (not shown) can be placed above the display 1117. Figure 11A As shown, an ultrasonic transceiver 1113, including an electrode layer 1115, is positioned on the side of a rigid substrate 1111 opposite to the display 1117. In some implementations, the rigid substrate 1111 has a thickness between about 5 μm and about 500 μm, between about 50 μm and about 200 μm, or between about 80 μm and about 120 μm. The rigid substrate 1111 provides acoustic coupling with the ultrasonic fingerprint sensor system 1110, such that suitable acoustic boundary conditions allow ultrasonic waves to propagate and be reflected with minimal interference. In some implementations, the rigid substrate 1111 is a glass substrate. The glass substrate typically provides sufficient acoustic coupling with the piezoelectric layer 1114 in the ultrasonic fingerprint sensor system 1110. The glass substrate serves as an acoustic reflector and filter, allowing ultrasonic waves to propagate with minimal acoustic interference, and the reflected ultrasonic waves to be detected by the ultrasonic fingerprint sensor system 1110 with minimal acoustic interference.

[0107] Figure 11BA cross-sectional schematic diagram of an example ultrasonic fingerprint sensor system with a flexible substrate beneath a display, according to some implementations, is shown. The ultrasonic fingerprint sensor system 1120 includes a flexible substrate 1121 having multiple sensor circuits 1122. The ultrasonic fingerprint sensor system 1120 includes an ultrasonic transceiver 1123 coupled to the flexible substrate 1121, wherein the ultrasonic transceiver includes a piezoelectric layer 1124 coupled to the flexible substrate 1121 and an electrode layer 1125 coupled to the piezoelectric layer 1124. In some implementations, the electrode layer 1125 may be divided into multiple electrode segments. The electrode layer 1125 may include a thick metal layer, such as a thick silver ink electrode as described above. In some implementations, an FPC (not shown) may be coupled to the flexible substrate 1121, wherein the FPC may include one or more dielectric layers and one or more interconnects (e.g., traces, vias, pads). The FPC may be electrically coupled to a controller or other circuitry for signal processing of signals to / from the sensor circuits 1122.

[0108] The ultrasonic transceiver 1123 can be attached to the display 1127 via adhesive 1128. A pressure plate, cover glass, cover plate, or outer layer (not shown) can be placed above the display 1127. Figure 11B As shown, an ultrasonic transceiver 1123, including an electrode layer 1125, is positioned on the side of the flexible substrate 1121 facing the display 1127. In some implementations, a spacer layer 1129 may be placed between the adhesive 1128 and the display 1127 to provide additional isolation between the ultrasonic transceiver 1123 and the display 1127. In some implementations, the thickness of the flexible substrate 121 is between about 10 μm and about 100 μm, between about 25 μm and about 75 μm, or about 50 μm. The flexible substrate 121 may comprise a plastic material such as polyimide, polyethylene terephthalate (PET), or polyethylene naphthalate (PEN). In some implementations, the flexible substrate 1121 comprises polyimide. The thickness and composition of the flexible substrate 121 may be configured for acoustic coupling with the ultrasonic fingerprint sensor system 1120.

[0109] Generally, ultrasonic fingerprint sensor systems can be oriented in either a "receiver-down" or "receiver-up" configuration. In a "receiver-down" configuration, the piezoelectric layer (transceiver or receiver) is below the substrate, and the substrate can be in the acoustic path of the ultrasonic waves passing through the display. In a "receiver-up" configuration, the piezoelectric layer (transceiver or receiver) covers the top of the substrate, and the substrate does not necessarily need to be in the acoustic path of the ultrasonic waves passing through the display. Instead, the electrode layer is in the acoustic path. Figure 11A-11B The piezoelectric layer is coupled to the substrate. Figure 11A In the ultrasonic fingerprint sensor system 1110, the receiver-down orientation is adopted, with the rigid substrate 1111 positioned in the acoustic path. Figure 11BIn the diagram, the ultrasonic fingerprint sensor system 1120 is in a "receiver-up" orientation, with the electrode layer 1125 in the acoustic path. As used herein, terms such as "below," "under," "above," "overlapping," "below," "on top," "bottom," "upward," "downward," "front," and "backward" are relative terms and may be used for the purpose of simply describing the figures and may be used to indicate relative positions on a page corresponding to the orientation of the figures in the correct orientation. However, these terms are not limiting and may not reflect the actual orientation or relative position of the implemented elements.

[0110] Figure 11A-11B Electrode layers 1115 and 1125 can be used as layers with high acoustic impedance values. Figure 11A The intermediate electrode layer 1115 can be located below the piezoelectric layer 1114, while... Figure 11B The intermediate electrode layer 1125 can cover the piezoelectric layer 1124. Alternatively, a layer with a high acoustic impedance value (such as an electrode layer) can be placed adjacent to the piezoelectric layer. The layer with a high acoustic impedance value provides effective acoustic coupling with the ultrasonic fingerprint sensor system. Figure 11A In this configuration, the rigid substrate 1111 and / or the electrode layer 1115 can be used as a layer with a high acoustic impedance value adjacent to the piezoelectric layer 1114, wherein the rigid substrate 1111 is in the acoustic path. Figure 11B In this process, electrode layer 1125 can be used as a layer with a high acoustic impedance value adjacent to piezoelectric layer 1124, wherein electrode layer 1125 is in the acoustic path.

[0111] Sound waves are longitudinal waves with the same direction of vibration as their direction of travel. Sound waves propel particles in a medium, regardless of whether the medium is solid, liquid, or gas. Sound waves travel at the speed of sound, which depends on the medium they pass through. Acoustic impedance measurements in a material are relative to the acoustic flow generated by the sound pressure applied to that material. Acoustic impedance determines the reflection and transmission of sound energy at boundaries. If the acoustic impedances of two media are very different, most of the sound energy will be reflected or absorbed, rather than transmitted across the boundary. Acoustic impedance values ​​can be measured in Pascals-seconds per meter (Pa-s / m) or Rayles.

[0112] Layers or materials with high acoustic impedance values ​​may be referred to as “hard” materials in this document, while those with low acoustic impedance values ​​may be referred to as “soft” materials. Acoustic impedance values ​​can be measured in Rayl or MRayl. Acoustic impedance is a function of the density of the medium multiplied by the speed at which sound travels through it. Table 1 below lists a range of materials and their acoustic impedance values. High acoustic impedance values ​​can be greater than about 5.0 MRayl or greater than about 8.0 MRayl, while low acoustic impedance values ​​can range from about 0.0 MRayl to about 5.0 MRayl. Generally, metals, ceramics, and glass can be considered to have high acoustic impedance values; plastics and polymers can be considered to have low acoustic impedance values; and air can be considered to have very low acoustic impedance values.

[0113] Table 1

[0114]

[0115]

[0116] As shown in Table 1, thick layers of copper, glass, or silver can provide high acoustic impedance values ​​compared to piezoelectric polymers. These materials can enable effective acoustic coupling in ultrasonic fingerprint sensor systems to achieve improved image quality. However, these materials may also introduce other problems into ultrasonic fingerprint sensor systems. For example, glass substrates may limit the construction of flexible displays and sensors spanning large areas, while silver electrodes may limit the formation of electrode segments with small gap dimensions. In some implementations, flexible substrates can be used instead of glass substrates in ultrasonic fingerprint sensor systems while incorporating layers with high acoustic impedance values. In some implementations, non-conductive acoustic layers, which may have high acoustic impedance values ​​(or at least high density), can be used instead of silver electrodes in ultrasonic fingerprint sensor systems.

[0117] Figure 12AA cross-sectional schematic diagram of an example ultrasonic fingerprint sensor system with a rigid substrate and a non-conductive acoustic layer, according to some implementations, is shown. The ultrasonic fingerprint sensor system 1210 includes a rigid substrate 1211 having a plurality of sensor circuits 1212. The plurality of sensor circuits 1212 may include a plurality of sensor pixel circuits arranged in an array, wherein each sensor pixel circuit can be configured to convert surface charges generated in a piezoelectric layer into electrical signals. The ultrasonic fingerprint sensor system 1210 includes an ultrasonic transceiver 1213 coupled to the rigid substrate 1211, wherein the ultrasonic transceiver 1213 is below the rigid substrate 1211 and in a “receiver-down” orientation. The ultrasonic transceiver 1213 includes a piezoelectric layer 1214 coupled to the rigid substrate 1211, an electrode layer 1215 coupled to the piezoelectric layer 1214, and a non-conductive acoustic layer 1216 adjacent to and below the piezoelectric layer 1214. The electrode layer 1215 may be located between the piezoelectric layer 1214 and the non-conductive acoustic layer 1216. In some implementations, the electrode layer 1215 may be divided into multiple electrode segments. In some implementations, the ultrasonic fingerprint sensor system 1210 further includes a passivation layer 1217 located beneath the non-conductive acoustic layer 1216. In some implementations, the FPC (not shown) may be coupled to a rigid substrate 1211.

[0118] An ultrasonic fingerprint sensor system 1210 can be attached to a display 1218 via an adhesive 1219, specifically a rigid substrate 1211 being attached to the display 1218 via the adhesive 1219. In some implementations, the adhesive 1219 includes a pressure-sensitive adhesive or epoxy resin. In some implementations, the display 1218 includes an OLED display. A pressure plate, cover glass, cover plate, or outer layer (not shown) may be placed above the display 1218. Figure 12A As shown, an ultrasonic transceiver 1213, including a non-conductive acoustic layer 1216, is placed on the side of a rigid substrate 1211 opposite to the display 1218.

[0119] In some implementations, the rigid substrate 1211 has a thickness between about 5 μm and about 500 μm, between about 50 μm and about 200 μm, or between about 80 μm and about 120 μm. In some implementations, the rigid substrate 1211 comprises a glass substrate. The thickness and composition of the rigid substrate 121 can be configured for acoustic coupling with the ultrasonic fingerprint sensor system 1210. In some implementations, the piezoelectric layer 1214 has a thickness between about 5 μm and about 30 μm or between about 5 μm and about 15 μm. The piezoelectric layer 1214 is configured to generate ultrasonic waves. The piezoelectric layer 1214 is also configured to receive reflections of ultrasonic waves. In some implementations, the piezoelectric layer 1214 may also be referred to as a piezoelectric transceiver layer or transceiver layer. Examples of suitable piezoelectric materials include PVDF or PVDF-TrFE copolymers.

[0120] In some implementations, electrode layer 1215 includes a thin conductive layer coupled to and below piezoelectric layer 1214. Non-conductive acoustic layer 1216 includes a thick layer having a high density or high acoustic impedance value, wherein non-conductive acoustic layer 1216 is below electrode layer 1215 and adjacent to piezoelectric layer 1214. As used herein, "adjacent to" a piezoelectric layer can mean a layer placed within 20 μm of or closer to the piezoelectric layer. This can be done whether the non-conductive acoustic layer is below or above the piezoelectric layer. In some implementations, the thickness of non-conductive acoustic layer 1216 is significantly greater than that of electrode layer 1215. As used herein, "significantly greater" can mean that the thickness of the non-conductive acoustic layer is at least twice the thickness of the electrode layer. In some implementations, the thickness of non-conductive acoustic layer 1216 is between about 5 μm and about 50 μm, between about 10 μm and about 30 μm, or between about 15 μm and about 25 μm. In some implementations, the thickness of electrode layer 1215 is between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm. Such a thickness range may be suitable when electrode layer 1215 comprises aluminum, nickel, copper, or a combination thereof. In some implementations, the thickness of electrode layer 1215 is between about 3 μm and about 12 μm, or between about 5 μm and about 10 μm. Such a thickness range may be suitable when electrode layer 1215 comprises silver ink. In some implementations, non-conductive acoustic layer 1216 comprises a dielectric material having an acoustic impedance value greater than about 8.0 MRayl. In some implementations, electrode layer 1215 comprises aluminum, nickel, copper, or a combination thereof. In some implementations, passivation layer 1217 comprises an electrically insulating material used as a backing layer for ultrasonic transceiver 1213, wherein passivation layer 1217 provides a smooth surface to reduce noise. In some implementations, the outer surface of the passivation layer 1217 has a roughness value equal to or less than about 5 nm (in terms of RMS). In some implementations, the passivation layer 1217 comprises a photoresist, a photoimageable epoxy resin, or other smooth electrical insulating material.

[0121] Figure 12BA cross-sectional schematic diagram of an example ultrasonic fingerprint sensor system with a flexible substrate and a non-conductive acoustic layer, according to some implementations, is shown. The ultrasonic fingerprint sensor system 1220 includes a flexible substrate 1221 having a plurality of sensor circuits 1222. The plurality of sensor circuits 1222 may include a plurality of sensor pixel circuits arranged in an array, wherein each sensor pixel circuit can be configured to convert surface charges generated in a piezoelectric layer into electrical signals. The ultrasonic fingerprint sensor system 1220 includes an ultrasonic transceiver 1223 coupled to the flexible substrate 1221, wherein the ultrasonic transceiver 1223 covers the flexible substrate 1221 and is in a “receiver-up” orientation. The ultrasonic transceiver 1223 includes a piezoelectric layer 1224 coupled to the flexible substrate 1221, an electrode layer 1225 coupled to the piezoelectric layer 1224, and a non-conductive acoustic layer 1226 adjacent to and covering the piezoelectric layer 1224. The electrode layer 1225 may be between the piezoelectric layer 1224 and the non-conductive acoustic layer 1226. In some implementations, the electrode layer 1225 and the non-conductive acoustic layer 1226 are in the acoustic path. In some implementations, the electrode layer 1225 can be divided into multiple electrode segments. In some implementations, the FPC (not shown) can be coupled to the flexible substrate 1221.

[0122] The ultrasonic fingerprint sensor system 1220 can be attached to the display 1227 via an adhesive 1228, wherein specifically a non-conductive acoustic layer 1226 or a passivation layer (not shown) is attached to the display 1227 via the adhesive 1228. In some implementations, the adhesive 1228 includes a pressure-sensitive adhesive or epoxy resin. In some implementations, the display 1227 includes an OLED display. A pressure plate, cover glass, cover plate, or outer layer (not shown) may be placed above the display 1227. In some implementations, a spacer layer 1229 may be placed between the adhesive 1228 and the display 1227 to provide additional isolation between the ultrasonic transceiver 1223 and the display 1227. Figure 12B As shown, an ultrasonic transceiver 1223, including a non-conductive acoustic layer 1226, is placed on the side of the flexible substrate 1221 facing the display 1227. The non-conductive acoustic layer 1226 is placed in the acoustic path between the piezoelectric layer 1224 and the display 1227.

[0123] In some implementations, the flexible substrate 1221 has a thickness between about 10 μm and about 100 μm, between about 25 μm and about 75 μm, or about 50 μm. The flexible substrate 1221 may comprise a plastic material such as polyimide, PET, or PEN. In some implementations, the flexible substrate 1221 comprises polyimide. The thickness and composition of the flexible substrate 1221 may be configured for acoustic coupling with the ultrasonic fingerprint sensor system 1220. In some implementations, the piezoelectric layer 1224 has a thickness between about 5 μm and about 30 μm, or between about 5 μm and about 15 μm. The piezoelectric layer 1224 is configured to generate ultrasonic waves. The piezoelectric layer 1224 is also configured to receive reflections of ultrasonic waves. Examples of suitable piezoelectric materials include PVDF or PVDF-TrFE copolymers.

[0124] In some implementations, electrode layer 1225 includes a thin conductive layer coupled to and covering piezoelectric layer 1224. Non-conductive acoustic layer 1226 includes a thick layer having a high density or high acoustic impedance value, wherein non-conductive acoustic layer 1226 covers electrode layer 1225 and is adjacent to piezoelectric layer 1224. In some implementations, the thickness of non-conductive acoustic layer 1226 is significantly greater than that of electrode layer 1225. In some implementations, the thickness of non-conductive acoustic layer 1226 is between about 5 μm and about 50 μm, between about 10 μm and about 30 μm, or between about 15 μm and about 25 μm. In some implementations, the thickness of electrode layer 1225 is between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm. Such a thickness range may be suitable when electrode layer 1225 comprises aluminum, nickel, copper, or a combination thereof. In some implementations, the thickness of electrode layer 1225 is between about 3 μm and about 12 μm, or between about 5 μm and about 10 μm. Such a thickness range may be suitable when electrode layer 1225 comprises silver ink. In some implementations, the non-conductive acoustic layer 1226 comprises a dielectric material having an acoustic impedance value greater than about 8.0 MRayl. In some implementations, electrode layer 1225 comprises aluminum, nickel, copper, or a combination thereof. Electrode layer 1225 may further comprise additional layers, such as an adhesive layer (e.g., TiN) having aluminum, nickel, and / or copper.

[0125] like Figure 12A-12B As shown, a thick non-conductive acoustic layer is provided with a thin conductive layer. This is also true in... Figures 13A-13BExamples of ultrasonic fingerprint sensor systems, such as 14A-14C, 15A-15C, and others throughout this disclosure, are shown. Specifically, a thick non-conductive acoustic layer is disposed on and in contact with a thin conductive layer. The thick non-conductive acoustic layer may be directly below or directly over the thin conductive layer, and may cover all or almost all of the thin conductive layer. The thick non-conductive acoustic layer and the thin conductive layer may be adjacent to the piezoelectric layer of the ultrasonic transmitter / transceiver. In some implementations, the thick non-conductive acoustic layer and the thin conductive layer are coupled to the piezoelectric layer and may be in direct contact with the piezoelectric layer. Figure 11A-11B The film stacking in the process integrates high acoustic impedance functionality with electrode functionality within the electrode layer (e.g., a silver-ink electrode or a thick metal layer), but Figure 12A-12B The film stacking in 13A-13B, 14A-14C and 15A-15C separates the high acoustic impedance function in the non-conductive acoustic layer (e.g., a thick high impedance layer) from the electrode function in the electrode layer (e.g., a thin conductive layer).

[0126] The non-conductive acoustic layer has a high density. In some implementations, the non-conductive acoustic layer can have a density of approximately 3500 kg / m³. 3 Up to approximately 10,000 kg / m 3 The density between [a certain value]. The non-conductive acoustic layer is electrically insulating. In some implementations, the bulk resistivity of the non-conductive acoustic layer can be equal to or greater than approximately 1 x 10⁻⁶. 9 ohm-m, equal to or greater than approximately 1 x 10 11 ohm-m or equal to or greater than approximately 1 x 10 11 ohm-m. In some implementations, the non-conductive acoustic layer has a high acoustic impedance value, such as an acoustic impedance value greater than about 8.0 MRayl. In some implementations, the breakdown field of the non-conductive acoustic layer can be equal to or greater than about 10 MV / m. In some implementations, the velocity of sound passing through the non-conductive acoustic layer (at 25°C) can be between about 1500 m / s and about 4000 m / s. In some implementations, the attenuation of sound waves passing through the non-conductive acoustic layer can be equal to or less than about 25 dB / cm. In some implementations, voids and / or particles may be present in the non-conductive acoustic layer. The maximum particle size in the non-conductive acoustic layer is between about 0.5 μm and about 3 μm, and the maximum void size is equal to or less than about 1 μm. In some implementations, the glass transition temperature of the non-conductive layer is equal to or less than 60°C. The non-conductive acoustic layer may also be referred to as a high acoustic impedance layer, high impedance layer, high impedance acoustic layer, high density layer, high density acoustic layer, etc. In some implementations, the high impedance layer comprises multiple dense particles. For example, the high-resistivity layer can be an organic binder with multiple particles in a matrix form. In some implementations, the high-resistivity layer can be screen-printed, stencil-printed, or laminated as a dry film.

[0127] Figure 13AA schematic cross-sectional view of an example ultrasonic fingerprint sensor system, according to some implementations, is shown. The ultrasonic fingerprint sensor system 1310 includes a rigid substrate 1311 having multiple sensor circuits 1312. The ultrasonic fingerprint sensor system 1310 includes an ultrasonic transceiver 1313 coupled to the rigid substrate 1311, wherein the ultrasonic transceiver 1313 is below the rigid substrate 1311 and in a "receiver-down" orientation. The ultrasonic transceiver 1313 includes a piezoelectric layer 1314 coupled to the rigid substrate 1311, an electrode layer 1315a coupled to the piezoelectric layer 1314, and a non-conductive acoustic layer 1316 adjacent to and below the piezoelectric layer 1314. The electrode layer 1315a may be located between the piezoelectric layer 1314 and the non-conductive acoustic layer 1316. The ultrasonic transceiver 1313 further includes a routing layer 1315b and an electrically insulating layer 1317, wherein the electrically insulating layer 1317 is sandwiched between the electrode layer 1315a and the routing layer 1315b. In some implementations, the electrode layer 1315a may be divided into multiple electrode segments. In some implementations, the ultrasonic fingerprint sensor system 1310 further includes a passivation layer 1318 located beneath the non-conductive acoustic layer 1316. In some implementations, an FPC (not shown) may be coupled to a rigid substrate 1311.

[0128] An ultrasonic fingerprint sensor system 1310 can be attached to a display 1319 via an adhesive 1320, specifically a rigid substrate 1311 is attached to the display 1319 via the adhesive 1320. In some implementations, the adhesive 1320 includes a pressure-sensitive adhesive or epoxy resin. In some implementations, the display 1319 includes an OLED display. A pressure plate, cover glass, cover plate, or outer layer (not shown) may be placed above the display 1319. Figure 13A As shown, an ultrasonic transceiver 1313, including a non-conductive acoustic layer 1316, is placed on the side of a rigid substrate 1311 opposite to the display 1319.

[0129] In some implementations, the rigid substrate 1311 has a thickness between about 5 μm and about 500 μm, between about 50 μm and about 200 μm, or between about 80 μm and about 120 μm. In some implementations, the rigid substrate 1311 comprises a glass substrate. The thickness and composition of the rigid substrate 1311 can be configured for acoustic coupling with the ultrasonic fingerprint sensor system 1310. In some implementations, the piezoelectric layer 1314 has a thickness between about 5 μm and about 30 μm, or between about 5 μm and about 15 μm. The piezoelectric layer 1314 is configured to generate ultrasonic waves. The piezoelectric layer 1314 is also configured to receive reflections of ultrasonic waves. Examples of suitable piezoelectric materials include PVDF or PVDF-TrFE copolymers.

[0130] In some implementations, electrode layer 1315a includes a thin conductive layer coupled to and beneath piezoelectric layer 1314. Non-conductive acoustic layer 1316 includes a thick layer having a high density or high acoustic impedance value, wherein non-conductive acoustic layer 1316 is beneath and adjacent to piezoelectric layer 1314, and routing layer 1315b. Non-conductive acoustic layer 1316 may be separated from piezoelectric layer 1314 by electrode layer 1315a, routing layer 1315b, and electrical insulating layer 1317. However, electrode layer 1315a, routing layer 1315b, and electrical insulating layer 1317 are not so thick that non-conductive acoustic layer 1316 is not considered adjacent to piezoelectric layer 1314. In some implementations, electrical insulating layer 1317 includes photoimageable epoxy resin. The photoimageable epoxy resin can be a polymeric material having a curing temperature equal to or lower than about 150°C, equal to or lower than about 140°C, or equal to or lower than about 120°C. For example, the photoimageable epoxy resin may include SU-8. The electrically insulating layer 1317 may have a thickness between about 3 μm and about 15 μm, or between about 5 μm and about 10 μm. The electrically insulating layer 1317 may be thick enough to reduce the electrical coupling between the electrode layer 1315a and the routing layer 1315b and to minimize the additional load. However, the electrically insulating layer 1317 may be thin enough to ensure acoustic coupling between the non-conductive acoustic layer 1316 and the piezoelectric layer 1314. Thus, the separation caused by the thickness of the electrically insulating layer 1317 is not so significant that the high-impedance layer (i.e., the non-conductive acoustic layer 1316) is no longer adjacent to the piezoelectric layer 1314, which would otherwise have reduced the signal strength of the ultrasound. In some implementations, the thickness of the non-conductive acoustic layer 1316 is significantly greater than the thickness of each of the electrode layer 1315a and the routing layer 1315b. In some implementations, the thickness of the non-conductive acoustic layer 1316 is between about 5 μm and about 50 μm, between about 10 μm and about 30 μm, or between about 15 μm and about 25 μm. In some implementations, the thickness of each of the electrode layer 1315a and the routing layer 1315b is between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm. Such thickness ranges may be suitable when the electrode layer 1315a and the routing layer 1315b comprise aluminum, nickel, copper, or combinations thereof. In some implementations, the thickness of the electrode layer 1315a is between about 3 μm and about 12 μm, or between about 5 μm and about 10 μm. When electrode layer 1315a comprises silver ink, such a thickness range may be suitable. In some implementations, non-conductive acoustic layer 1316 comprises a dielectric material having an acoustic impedance value greater than about 8.0 MRayl. In some implementations, one or both of electrode layer 1315a and routing layer 1315b comprise aluminum, nickel, copper, or a combination thereof.In some implementations, the passivation layer 1318 comprises an electrically insulating material serving as a backing layer for the ultrasonic transceiver 1313, wherein the passivation layer 1318 provides a smooth surface to reduce noise. In some implementations, the outer surface of the passivation layer 1318 has a roughness value equal to or less than about 5 nm (in terms of RMS). In some implementations, the passivation layer 1318 comprises a photoresist, a photoimageable epoxy resin, or other smooth electrically insulating material.

[0131] Figure 13B A cross-sectional schematic diagram of an example ultrasonic fingerprint sensor system, according to some implementations, is shown. The ultrasonic fingerprint sensor system 1330 includes a flexible substrate 1331 having multiple sensor circuits 1332. The ultrasonic fingerprint sensor system 1330 includes an ultrasonic transceiver 1333 coupled to the flexible substrate 1331, wherein the ultrasonic transceiver 1333 covers the flexible substrate 1331 and is in a "receiver-up" orientation. The ultrasonic transceiver 1333 includes a piezoelectric layer 1334 coupled to the flexible substrate 1331, an electrode layer 1335a coupled to the piezoelectric layer 1334, and a non-conductive acoustic layer 1336 adjacent to and covering the piezoelectric layer 1334. The electrode layer 1335a may be located between the piezoelectric layer 1334 and the non-conductive acoustic layer 1336. The ultrasonic transceiver 1333 further includes a routing layer 1335b and an electrically insulating layer 1337, wherein the electrically insulating layer 1337 is sandwiched between the electrode layer 1335a and the routing layer 1335b. In some implementations, the electrode layer 1335a and the non-conductive acoustic layer 1336 are in the acoustic path. In some implementations, the electrode layer 1335a may be divided into multiple electrode segments. In some implementations, an FPC (not shown) may be coupled to a flexible substrate 1331.

[0132] The ultrasonic fingerprint sensor system 1330 can be attached to the display 1338 via an adhesive 1339, wherein specifically a non-conductive acoustic layer 1336 or a passivation layer (not shown) is attached to the display 1338 via the adhesive 1339. In some implementations, the adhesive 1339 includes a pressure-sensitive adhesive or an epoxy resin. In some implementations, the display 1338 includes an OLED display. A pressure plate, cover glass, cover plate, or outer layer (not shown) may be placed above the display 1338. In some implementations, a spacer layer 1340 may be placed between the adhesive 1339 and the display 1338 to provide additional isolation between the ultrasonic transceiver 1333 and the display 1338. Figure 13B As shown, an ultrasonic transceiver 1333, including a non-conductive acoustic layer 1336, is placed on the side of the flexible substrate 1331 facing the display 1338. The non-conductive acoustic layer 1336 is placed in the acoustic path between the piezoelectric layer 1334 and the display 1338.

[0133] In some implementations, the flexible substrate 1331 has a thickness between about 10 μm and about 100 μm, between about 25 μm and about 75 μm, or about 50 μm. The flexible substrate 1331 may comprise an elastic material such as polyimide, PET, or PEN. In some implementations, the flexible substrate 1331 comprises polyimide. The thickness and composition of the flexible substrate 1331 may be configured for acoustic coupling with the ultrasonic fingerprint sensor system 1330. In some implementations, the piezoelectric layer 1334 has a thickness between about 5 μm and about 30 μm, or between about 5 μm and about 15 μm. The piezoelectric layer 1334 is configured to generate ultrasonic waves. The piezoelectric layer 1334 is also configured to receive reflections of ultrasonic waves. Examples of suitable piezoelectric materials include PVDF or PVDF-TrFE copolymers.

[0134] In some implementations, electrode layer 1335a includes a thin conductive layer coupled to and covering piezoelectric layer 1334. Non-conductive acoustic layer 1336 includes a thick layer having a high density or high acoustic impedance value, wherein non-conductive acoustic layer 1336 covers and is adjacent to piezoelectric layer 1334 above electrode layer 1335a and routing layer 1335b. Non-conductive acoustic layer 1336 may be separated from piezoelectric layer 1334 by electrode layer 1335a, routing layer 1335b, and electrical insulating layer 1337. However, electrode layer 1335a, routing layer 1335b, and electrical insulating layer 1337 are not so thick that non-conductive acoustic layer 1336 is not considered adjacent to piezoelectric layer 1334. In some implementations, electrical insulating layer 1337 includes a photoimageable epoxy resin, such as SU-8. The electrically insulating layer 1337 may have a thickness between about 3 μm and about 15 μm, or between about 5 μm and about 10 μm. The electrically insulating layer 1337 may be thick enough to reduce the electrical coupling between the electrode layer 1335a and the routing layer 1335b and to minimize additional load. However, the electrically insulating layer 1337 may be thin enough to ensure acoustic coupling between the non-conductive acoustic layer 1336 and the piezoelectric layer 1334. In some implementations, the thickness of the non-conductive acoustic layer 1336 is significantly greater than the thickness of each of the electrode layer 1335a and the routing layer 1335b. In some implementations, the thickness of the non-conductive acoustic layer 1336 is between about 5 μm and about 50 μm, between about 10 μm and about 30 μm, or between about 15 μm and about 25 μm. In some implementations, the thickness of each of electrode layer 1335a and routing layer 1335b is between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm. Such a thickness range may be suitable when electrode layer 1335a and routing layer 1335b comprise aluminum, nickel, copper, or combinations thereof. In some implementations, the thickness of electrode layer 1335a is between about 3 μm and about 12 μm, or between about 5 μm and about 10 μm. Such a thickness range may be suitable when electrode layer 1335a comprises silver ink. In some implementations, non-conductive acoustic layer 1336 comprises a dielectric material having an acoustic impedance value greater than about 8.0 MRayl. In some implementations, one or both of electrode layer 1335a and routing layer 1335b comprise aluminum, nickel, copper, or combinations thereof. Each of the electrode layer 1335a and the routing layer 1335b may further include an additional layer, such as an adhesive layer having aluminum, nickel and / or copper (e.g., TiN).

[0135] Figures 14A-14C Cross-sectional schematic diagrams are shown of various example ultrasonic fingerprint sensor systems implemented on a rigid substrate and having separate ultrasonic transmitters and receivers. For example... Figures 14A-14C and Figures 15A-15CSeparating the receiver and transmitter functions of an ultrasonic fingerprint sensor system can improve performance and efficiency, but may increase complexity / cost.

[0136] exist Figure 14A In this embodiment, the ultrasonic fingerprint sensor system 1410 includes a rigid substrate 1411 having a plurality of sensor circuits 1412. The ultrasonic fingerprint sensor system 1410 includes an ultrasonic receiver 1413 configured to receive ultrasonic waves and an ultrasonic transmitter 1423 configured to generate ultrasonic waves. The ultrasonic fingerprint sensor system 1410 is oriented with a "receiver up" orientation, wherein the ultrasonic receiver 1413 is coupled to and covers the rigid substrate 1411. The ultrasonic receiver 1413 includes a piezoelectric receiver layer 1414 coupled to the rigid substrate 1411 and an electrode receiver layer 1415 coupled to and covering the piezoelectric receiver layer 1414. The ultrasonic transmitter 1423 is located below the rigid substrate 1411, on the side of the rigid substrate 1411 opposite to the ultrasonic receiver 1413. The ultrasonic transmitter 1423 includes a piezoelectric transmitter layer 1424 and a first electrode transmitter layer 1425a coupled to the piezoelectric transmitter layer 1424, wherein the first electrode transmitter layer 1425a is located between the rigid substrate 1411 and the piezoelectric transmitter layer 1424. In some implementations, the ultrasonic transmitter 1423 may further include a second electrode transmitter layer 1425b, such that a metallized electrode can clamp the piezoelectric transmitter layer 1424 and apply a voltage to drive the piezoelectric transmitter layer 1424. In some implementations, the ultrasonic fingerprint sensor system 1410 may be configured to be attached to a display 1417 via a first adhesive 1418 (such as epoxy resin), and specifically, the ultrasonic receiver 1413 may be configured to be attached to the display 1417 via the first adhesive 1418. In some implementations, the ultrasonic transmitter 1423 may be configured to be attached to the rigid substrate 1411 via a second adhesive 1428 (such as epoxy resin). In some implementations, the FPC (not shown) can be coupled to the rigid substrate 1411.

[0137] In some implementations, the rigid substrate 1411 has a thickness between about 5 μm and about 500 μm, between about 50 μm and about 200 μm, or between about 80 μm and about 120 μm. In some implementations, the rigid substrate 1411 comprises a glass substrate. The thickness and composition of the rigid substrate 1411 can be configured for acoustic coupling with the ultrasonic fingerprint sensor system 1410. In some implementations, the piezoelectric receiver layer 1414 and the piezoelectric emitter layer 1424 each have a thickness between about 5 μm and about 30 μm or between about 5 μm and about 15 μm. The piezoelectric receiver layer 1414 is configured to receive reflections of ultrasonic waves, and the piezoelectric emitter layer 1424 is configured to generate ultrasonic waves. Examples of suitable piezoelectric materials include PVDF or PVDF-TrFE copolymers.

[0138] Electrode receiver layer 1415 is continuous and unsegmented. Electrode receiver layer 1415 may be continuous across the span of ultrasound receiver 1413. In some implementations, electrode receiver layer 1415 may be coupled to an FPC. In some implementations, electrode receiver layer 1415 has a thickness between about 2 μm and about 100 μm, or between about 5 μm and about 50 μm. In some implementations, electrode receiver layer 1415 comprises silver ink, aluminum, copper, nickel, or combinations thereof. For example, electrode receiver layer 1415 comprises a 20 μm thick silver ink layer.

[0139] One or both of the first electrode emitter layer 1425a and the second electrode emitter layer 1425b are divided into multiple electrode segments. In some implementations, the first electrode emitter layer 1425a or the second electrode emitter layer 1425b is continuous and unsegmented. The first electrode emitter layer 1425a is coupled to and covers the piezoelectric emitter layer 1424, and the second electrode emitter layer 1425b is disposed on the side of the piezoelectric emitter layer 1424 opposite to the first electrode emitter layer 1425a. In some implementations, the second electrode emitter layer 1425b has a thickness between about 2 μm and about 100 μm or between about 5 μm and about 50 μm, and may include silver ink, aluminum, copper, nickel, or combinations thereof. For example, the second electrode emitter layer 1425b includes a 30 μm thick silver ink layer. In some implementations, the first electrode emitter layer 1425a serves as a layer with a high acoustic impedance value to provide effective acoustic coupling with the ultrasonic fingerprint sensor system 1410. In some implementations, the first electrode emitter layer 1425a has a thickness between about 2 μm and about 100 μm, or between about 5 μm and about 50 μm. In some implementations, the first electrode emitter layer 1425a comprises silver ink, which has a high acoustic impedance value. However, it will be appreciated that the first electrode emitter layer 1425a may comprise a thick non-conductive acoustic layer (such as a dielectric layer having an acoustic impedance value greater than about 8.0 MTayl) and a thin conductive layer (such as a thin layer of aluminum, copper, nickel, or a combination thereof).

[0140] In some implementations, the ultrasonic fingerprint sensor system 1410 may optionally include one or more protective layers. These protective layers may be used to improve adhesion between the layers, provide additional isolation between the layers, protect the components of the ultrasonic fingerprint sensor system 1410, provide a smooth surface on layers with high acoustic impedance values ​​to reduce noise, serve as impedance matching layers between high and low acoustic impedance layers, and / or provide electrical isolation between the components of the ultrasonic fingerprint sensor system 1410. In some implementations, a first protective layer 1419 may optionally be provided between a first adhesive 1418 and an electrode receiver layer 1415. In some implementations, a second protective layer 1427 may optionally be provided between a second adhesive 1428 and a first electrode emitter layer 1425a. In some implementations, a third protective layer 1429 may optionally be provided below the second electrode emitter layer 1425b. In some implementations, protective layers 1419, 1427, and 1429 may each have a thickness between about 2 μm and about 30 μm, or between about 5 μm and about 20 μm. In some implementations, protective layers 1419, 1427, and 1429 may comprise an acrylic resin.

[0141] exist Figure 14BIn this embodiment, the ultrasonic fingerprint sensor system 1430 includes a rigid substrate 1431 having multiple sensor circuits 1432. The ultrasonic fingerprint sensor system 1430 includes an ultrasonic receiver 1433 configured to receive ultrasonic waves and an ultrasonic transmitter 1443 configured to generate ultrasonic waves. The ultrasonic receiver 1433 is coupled to and covers the rigid substrate 1431. The ultrasonic receiver 1433 includes a piezoelectric receiver layer 1434 coupled to the rigid substrate 1431 and an electrode receiver layer 1435 coupled to and covering the piezoelectric receiver layer 1434. The ultrasonic transmitter 1443 is located below the rigid substrate 1431, on the side of the rigid substrate 1431 opposite to the ultrasonic receiver 1433. The ultrasonic transmitter 1443 includes a piezoelectric transmitter layer 1444 and a first electrode transmitter layer 1445a coupled to the piezoelectric transmitter layer 1444, wherein the first electrode transmitter layer 1445a is located between the rigid substrate 1431 and the piezoelectric transmitter layer 1444. In some implementations, the ultrasonic transmitter 1443 may further include a second electrode transmitter layer 1445b, such that a metallized electrode can clamp the piezoelectric transmitter layer 1444 and apply a voltage to drive the piezoelectric transmitter layer 1444. In some implementations, the ultrasonic fingerprint sensor system 1430 may be configured to be attached to a display 1437 via a first adhesive 1438 (such as epoxy resin), and specifically, the ultrasonic receiver 1433 may be configured to be attached to the display 1437 via the first adhesive 1438. In some implementations, the ultrasonic transmitter 1443 may be configured to be attached to the rigid substrate 1431 via a second adhesive 1428 (such as epoxy resin). In some implementations, the FPC (not shown) may be coupled to a rigid substrate 1431. In some implementations, the ultrasonic fingerprint sensor system 1430 includes a backing layer 1449, which serves to electrically isolate and protect the second electrode emitter layer 1445b. The backing layer 1449 may include an electrically insulating material, such as polyimide.

[0142] Figure 14B The rigid substrate 1431, piezoelectric receiver layer 1434, piezoelectric emitter layer 1444, and electrode receiver layer 1435 can be described in the above text. Figure 14AAs described in the text. However, instead of a thick metallized electrode layer (e.g., a silver ink electrode) coupled to the piezoelectric emitter layer 1444, the ultrasonic emitter 1443 includes a non-conductive acoustic layer 1446 between the rigid substrate 1431 and the piezoelectric emitter layer 1444. The non-conductive acoustic layer 1446 may be disposed on and directly cover the first electrode emitter layer 1445a, and the non-conductive acoustic layer 1446 may be considered adjacent to the piezoelectric emitter layer 1444. In some implementations, the non-conductive acoustic layer 1446 is used as a layer with a high acoustic impedance value to provide effective acoustic coupling with the ultrasonic fingerprint sensor system 1430. In some implementations, the first electrode emitter layer 1445a may be divided into multiple electrode segments. In some implementations, the non-conductive acoustic layer 1446 may have a thickness significantly greater than the thickness of the first electrode emitter layer 1445a. In some implementations, the non-conductive acoustic layer 1446 has a thickness between about 5 μm and about 100 μm, between about 10 μm and about 50 μm, or between about 15 μm and about 40 μm, and may include a dielectric material having an acoustic impedance value greater than about 8.0 MRayl. In some implementations, the first electrode emitter layer 1445a has a thickness between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm, and may include aluminum, copper, nickel, or combinations thereof. In some implementations, the second electrode emitter layer 1445b has a thickness between about 2 μm and about 100 μm, or between about 5 μm and about 50 μm, and may include silver ink, aluminum, copper, nickel, or combinations thereof. For example, the second electrode emitter layer 1445b includes a 30 μm thick copper layer. In some implementations, the second electrode emitter layer 1445b can be continuous and unsegmented.

[0143] In some implementations, the ultrasonic fingerprint sensor system 1430 may optionally include one or more protective layers. In some implementations, a first protective layer 1439 may optionally be provided between a first adhesive 1438 and an electrode receiver layer 1435. In some implementations, a second protective layer 1447 may optionally be provided between a second adhesive 1448 and a first electrode emitter layer 1445a. In some implementations, protective layers 1439 and 1447 may each have a thickness between about 2 μm and about 30 μm or between about 5 μm and about 20 μm. In some implementations, protective layers 1439 and 1447 may comprise an acrylic resin.

[0144] exist Figure 14CIn this embodiment, the ultrasonic fingerprint sensor system 1450 includes a rigid substrate 1451 having multiple sensor circuits 1452. The ultrasonic fingerprint sensor system 1450 includes an ultrasonic receiver 1453 configured to receive ultrasonic waves and an ultrasonic transmitter 1463 configured to generate ultrasonic waves. The ultrasonic receiver 1453 is coupled to and covers the rigid substrate 1451. The ultrasonic receiver 1453 includes a piezoelectric receiver layer 1454 coupled to the rigid substrate 1451 and an electrode receiver layer 1455 coupled to and covering the piezoelectric receiver layer 1454. The ultrasonic transmitter 1463 is located below the rigid substrate 1451, on the side of the rigid substrate 1451 opposite to the ultrasonic receiver 1453. The ultrasonic transmitter 1463 includes a piezoelectric transmitter layer 1464 and a first electrode transmitter layer 1465a coupled to the piezoelectric transmitter layer 1464, wherein the first electrode transmitter layer 1465a is located between the rigid substrate 1451 and the piezoelectric transmitter layer 1464. In some implementations, the ultrasonic transmitter 1463 may further include a second electrode transmitter layer 1465b coupled to the piezoelectric transmitter layer 1464, such that a metallized electrode can clamp the piezoelectric transmitter layer 1464 and apply a voltage to drive the piezoelectric transmitter layer 1464. Additionally, the ultrasonic transmitter 1463 may further include a non-conductive acoustic layer 1466 disposed on and directly covering the first electrode transmitter layer 1465a, wherein the non-conductive acoustic layer 1466 can be considered adjacent to the piezoelectric transmitter layer 1464. In some implementations, the ultrasonic fingerprint sensor system 1450 may be configured to be attached to a display 1457 via a first adhesive 1458 (such as epoxy resin), and specifically, the ultrasonic receiver 1453 may be configured to be attached to the display 1457 via the first adhesive 1458. In some implementations, the ultrasonic transmitter 1463 may be configured to be attached to a rigid substrate 1451 via a second adhesive 1468 (such as epoxy resin). In some implementations, an FPC (not shown) may be coupled to the rigid substrate 1451. In some implementations, the ultrasonic fingerprint sensor system 1450 includes a backing layer 1469, wherein the backing layer 1469 serves to electrically isolate and protect the second electrode transmitter layer 1465b. The backing layer 1469 may include an electrically insulating material, such as polyimide.

[0145] Figure 14C The rigid substrate 1451, piezoelectric receiver layer 1454, piezoelectric emitter layer 1464, and electrode receiver layer 1455 can be described in the above text. Figure 14A As described in the text. Furthermore, Figure 14C The various aspects of the non-conductive acoustic layer 1466 in the above text can be found in... Figure 14B As described in the text. However, with Figure 14BIn contrast, the second electrode emitter layer 1465b can be divided into multiple electrode segments, and the first electrode emitter layer 1465a can be continuous and unsegmented. Additionally or alternatively, the ultrasonic emitter 1463 further includes a routing layer 1465c beneath the backing layer 1469, wherein the routing layer 1465c provides additional circuitry in the ultrasonic fingerprint sensor system 1450 by and electrically connectable to the multiple electrode segments. In some implementations, the routing layer 1465c has a thickness between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm, and may comprise aluminum, copper, nickel, or combinations thereof.

[0146] In some implementations, the ultrasonic fingerprint sensor system 1450 may optionally include one or more protective layers. In some implementations, a first protective layer 1459 may optionally be provided between a first adhesive 1458 and an electrode receiver layer 1455. In some implementations, a second protective layer 1467 may optionally be provided between a second adhesive 1468 and a first electrode emitter layer 1465a. In some implementations, protective layers 1459 and 1467 may each have a thickness between about 2 μm and about 30 μm or between about 5 μm and about 20 μm. In some implementations, protective layers 1459 and 1467 may comprise an acrylic resin.

[0147] Figures 15A-15C A cross-sectional schematic diagram of various example ultrasonic fingerprint sensor systems implemented on a flexible substrate and having separate ultrasonic transmitters and receivers is shown.

[0148] exist Figure 15AIn this embodiment, the ultrasonic fingerprint sensor system 1510 includes a flexible substrate 1511 having a plurality of sensor circuits 1512. The ultrasonic fingerprint sensor system 1510 includes an ultrasonic transmitter 1523 configured to generate ultrasonic waves and an ultrasonic receiver 1513 configured to receive ultrasonic waves. The ultrasonic receiver 1513 is coupled to and covers the flexible substrate 1511, and the ultrasonic transmitter 1523 is coupled to and covers the ultrasonic receiver 1513. The ultrasonic receiver 1513 includes a piezoelectric receiver layer 1514 coupled to the flexible substrate 1511 and a first electrode layer 1515 coupled to and covering the piezoelectric receiver layer 1514. In some implementations, the first electrode layer 1515 serves as an electrode receiver layer to the piezoelectric receiver layer 1514. The ultrasonic transmitter 1523 includes a piezoelectric transmitter layer 1524 and a second electrode layer 1525 coupled to the piezoelectric transmitter layer 1524, wherein the second electrode layer 1525 covers the piezoelectric transmitter layer 1524. In some implementations, the piezoelectric transmitter layer 1524 is positioned between a first electrode layer 1515 and the second electrode layer 1525, such that a metallized electrode can clamp the piezoelectric transmitter layer 1524 and apply a voltage to drive the piezoelectric transmitter layer 1524. In some implementations, the ultrasonic fingerprint sensor system 1510 may be configured to be attached to a display 1517 via a first adhesive 1518 (such as epoxy resin), and specifically, the ultrasonic transmitter 1523 may be configured to be attached to the display 1517 via the first adhesive 1518. In some implementations, an FPC (not shown) may be coupled to a flexible substrate 1511.

[0149] In some implementations, the flexible substrate 1511 has a thickness between about 10 μm and about 100 μm, between about 25 μm and about 75 μm, or about 40 μm. The flexible substrate 1511 may comprise an elastic material such as polyimide, PET, or PEN. The thickness and composition of the flexible substrate 1511 may be configured for acoustic coupling with the ultrasonic fingerprint sensor system 1510. In some implementations, the piezoelectric receiver layer 1514 and the piezoelectric emitter layer 1524 each have a thickness between about 5 μm and about 30 μm or between about 5 μm and about 15 μm. The piezoelectric receiver layer 1514 is configured to receive reflected ultrasonic waves, and the piezoelectric emitter layer 1524 is configured to generate ultrasonic waves. Examples of suitable piezoelectric materials include PVDF or PVDF-TrFE copolymers.

[0150] The first electrode layer 1515 may be continuous and unsegmented. The first electrode layer 1515 may be continuous across the span of the ultrasound receiver 1513. In some implementations, the first electrode layer 1515 may be coupled to an FPC. In some implementations, the first electrode layer 1515 has a thickness between about 3 μm and about 12 μm, or between about 5 μm and about 10 μm. Such a thickness range is suitable when the first electrode layer 1515 comprises silver ink. In some implementations, the first electrode layer 1515 has a thickness between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm. Such a thickness range is suitable when the first electrode layer 1515 comprises aluminum, copper, nickel, or a combination thereof.

[0151] The second electrode layer 1525 can be divided into multiple electrode segments. The second electrode layer 1525 is coupled to and covers the piezoelectric emitter layer 1524, and a first electrode layer 1515 is disposed on the side of the piezoelectric emitter layer 1524 opposite to the second electrode layer 1525. In some implementations, the second electrode layer 1525 has a thickness between about 2 μm and about 100 μm, or between about 5 μm and about 50 μm, and may include silver ink, aluminum, copper, nickel, or combinations thereof. For example, the second electrode layer 1525 includes a 30 μm thick silver ink layer. In some implementations, the second electrode layer 1525 is used as a layer with a high acoustic impedance value to provide effective acoustic coupling with the ultrasonic fingerprint sensor system 1510, wherein the second electrode layer 1525 is positioned in the acoustic path between the piezoelectric emitter layer 1524 and the display 1517. However, it will be understood that the second electrode layer 1525 may include a thick non-conductive acoustic layer (such as a dielectric layer having an acoustic impedance value greater than about 8.0 MTayl) and a thin conductive layer (such as a thin layer of aluminum, copper, nickel or a combination thereof).

[0152] exist Figure 15BIn this embodiment, the ultrasonic fingerprint sensor system 1530 includes a flexible substrate 1531 having a plurality of sensor circuits 1532. The ultrasonic fingerprint sensor system 1530 includes an ultrasonic transmitter 1543 configured to generate ultrasonic waves and an ultrasonic receiver 1533 configured to receive ultrasonic waves. The ultrasonic receiver 1533 is coupled to and covers the flexible substrate 1531, and the ultrasonic transmitter 1543 is coupled to and covers the ultrasonic receiver 1533. The ultrasonic receiver 1533 includes a piezoelectric receiver layer 1534 coupled to the flexible substrate 1531 and a first electrode layer 1535 coupled to and covering the piezoelectric receiver layer 1534. In some implementations, the first electrode layer 1535 serves as an electrode receiver layer to the piezoelectric receiver layer 1534. The ultrasonic transmitter 1543 includes a piezoelectric transmitter layer 1544 and a second electrode layer 1545 coupled to the piezoelectric transmitter layer 1544, wherein the second electrode layer 1545 covers the piezoelectric transmitter layer 1544. In some implementations, the piezoelectric transmitter layer 1544 is positioned between the first electrode layer 1535 and the second electrode layer 1545, such that a metallized electrode can clamp the piezoelectric transmitter layer 1544 and apply a voltage to drive the piezoelectric transmitter layer 1544. In some implementations, the ultrasonic fingerprint sensor system 1530 may be configured to be attached to a display 1537 via a first adhesive 1538 (such as epoxy resin), and specifically, the ultrasonic transmitter 1543 may be configured to be attached to the display 1537 via the first adhesive 1538. In some implementations, an FPC (not shown) may be coupled to a flexible substrate 1531.

[0153] Figure 15B The various aspects of the flexible substrate 1531, the piezoelectric receiver layer 1534, and the piezoelectric transmitter layer 1544 can be described above. Figure 15AThe first electrode layer 1535 may or may not be divided into multiple electrode segments. The second electrode layer 1545 may or may not be divided into multiple electrode segments. In some implementations, each electrode segment of the first electrode layer 1535 may correspond to each electrode segment of the second electrode layer 1545. In some implementations, the first electrode layer 1535 has a thickness between about 3 μm and about 12 μm, or between about 5 μm and about 10 μm. Such a thickness range is suitable when the first electrode layer 1535 comprises silver ink. In some implementations, the first electrode layer 1535 has a thickness between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm. Such a thickness range is suitable when the first electrode layer 1535 comprises aluminum, copper, nickel, or a combination thereof. In some implementations, instead of a thick metal layer such as silver ink, the second electrode layer 1545 may comprise an FPC and a medium-thickness metal layer such as aluminum, copper, nickel, or a combination thereof. In some implementations, the FPC may comprise a plastic material such as polyimide. In some implementations, the medium-thickness metal layer of the second electrode layer 1545 has a thickness between about 5 μm and about 50 μm or between about 10 μm and about 30 μm, and the FPC of the second electrode layer 1545 has a thickness between about 5 μm and about 50 μm or between about 10 μm and about 30 μm. In some implementations, the second electrode layer 1545 is used as a layer with a high acoustic impedance value to provide effective acoustic coupling with the ultrasonic fingerprint sensor system 1530, wherein the second electrode layer 1545 is positioned in the acoustic path between the piezoelectric emitter layer 1544 and the display 1537.

[0154] exist Figure 15CIn this embodiment, the ultrasonic fingerprint sensor system 1550 includes a flexible substrate 1551 having multiple sensor circuits 1552. The ultrasonic fingerprint sensor system 1550 includes an ultrasonic transmitter 1563 configured to generate ultrasonic waves and an ultrasonic receiver 1553 configured to receive ultrasonic waves. The ultrasonic fingerprint sensor system 1550 is oriented with a "receiver up" orientation, wherein the ultrasonic receiver 1553 is coupled to and covers the flexible substrate 1551. The ultrasonic transmitter 1563 is located below the flexible substrate 1551, on the side of the flexible substrate 1551 opposite to the ultrasonic receiver 1553. The ultrasonic receiver 1553 includes a piezoelectric receiver layer 1554 coupled to the flexible substrate 1551 and an electrode receiver layer 1555 coupled to and covering the piezoelectric receiver layer 1554. The ultrasonic transmitter 1563 includes a piezoelectric transmitter layer 1564, a first electrode transmitter layer 1565a coupled to and covering the piezoelectric transmitter layer 1564, and a second electrode transmitter layer 1565b coupled to and below the piezoelectric transmitter layer 1564. The piezoelectric transmitter layer 1564 is positioned between the first electrode transmitter layer 1565a and the second electrode transmitter layer 1565b, such that a metallized electrode can clamp the piezoelectric transmitter layer 1564 and apply a voltage to drive it. In some implementations, the ultrasonic fingerprint sensor system 1550 may be configured to be attached to a display 1557 via a first adhesive 1558 (such as epoxy resin), and specifically, the ultrasonic receiver 1553 may be configured to be attached to the display 1557 via the first adhesive 1558. In some implementations, the ultrasonic transmitter 1563 may be configured to be attached to the flexible substrate 1551 via a second adhesive 1568 (such as epoxy resin). In some implementations, an FPC (not shown) may be coupled to the flexible substrate 1551.

[0155] Figure 15C The various aspects of the flexible substrate 1551, the piezoelectric receiver layer 1554, and the piezoelectric transmitter layer 1564 can be described above. Figure 15AThe electrode receiver layer 1555 can be continuous and unsegmented. The electrode receiver layer 1555 can be continuous across the span of the ultrasonic receiver 1553. In some implementations, the electrode receiver layer 1555 can be coupled to an FPC. In some implementations, the piezoelectric receiver layer 1555 has a thickness between about 3 μm and about 12 μm, or between about 5 μm and about 10 μm. Such a thickness range is suitable when the electrode receiver layer 1555 comprises silver ink. In some implementations, the electrode receiver layer 1555 has a thickness between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 100 nm and about 1000 nm. Such a thickness range is suitable when the electrode receiver layer 1555 comprises aluminum, copper, nickel, or a combination thereof.

[0156] One or both of the first electrode emitter layer 1565a and the second electrode emitter layer 1565b may be divided into multiple electrode segments. The first electrode emitter layer 1565a is coupled to and covers the piezoelectric emitter layer 1564, and the second electrode emitter layer 1565b is disposed on the side of the piezoelectric emitter layer 1564 opposite to the first electrode emitter layer 1565a. In some implementations, the first electrode emitter layer 1565a has a thickness between about 2 μm and about 100 μm, or between about 5 μm and about 50 μm, or between about 10 μm and about 40 μm, and may include silver ink, aluminum, copper, nickel, or combinations thereof. For example, the first electrode emitter layer 1565a includes a 30 μm thick copper layer. In some implementations, the first electrode emitter layer 1565a serves as a layer with a high acoustic impedance value to provide effective acoustic coupling with the ultrasonic fingerprint sensor system 1550, wherein the first electrode emitter layer 1565a is positioned in the acoustic path between the piezoelectric emitter layer 1564 and the display 1557. However, it will be appreciated that the first electrode emitter layer 1565a may comprise a thick non-conductive acoustic layer (such as a dielectric layer having an acoustic impedance value greater than about 8.0 MTayl) and a thin conductive layer (such as a thin layer of aluminum, copper, nickel, or a combination thereof). In some implementations, the second electrode emitter layer 1565b has a thickness between about 20 μm and about 500 μm, or between about 50 μm and about 300 μm, or between about 75 μm and about 150 μm, and may comprise silver ink, aluminum, copper, nickel, or a combination thereof. For example, the second electrode emitter layer 1565b comprises a 100 μm thick copper layer. In some implementations, the second electrode emitter layer 1565b can be used as an acoustic backing layer of the ultrasonic fingerprint sensor system 1550 to enhance acoustic coupling with the ultrasonic fingerprint sensor system 1550.

[0157] As discussed above, one or more electrode layers can be placed adjacent to a piezoelectric transmitter or transceiver to drive the piezoelectric layer to generate ultrasonic waves. To reduce the driving voltage, the electrode layer can be divided into multiple electrode segments, which can be separated from each other by electrically insulating gaps. The isolation of the electrode layers serves to conserve energy and to enable driving of the piezoelectric transmitter or transceiver across the entire array. In some implementations, the multiple electrode segments can be segmented according to a "strip" design, such as... Figure 16A As shown. In some implementations, multiple electrode segments can be segmented according to a "2-D island" design, such as... Figure 16B As shown.

[0158] Figure 16A A schematic diagram of an example ultrasonic fingerprint sensor system with segmented electrodes employing a "strip" design, according to some implementations, is shown. The ultrasonic fingerprint sensor system for an electronic device includes a plurality of electrode segments 1610 having electrically insulating gaps 1620 separating the plurality of electrode segments 1610 from each other. The plurality of electrode segments 1610 and the electrically insulating gaps 1620 cover the entire or nearly entire display of the electronic device. The electrically insulating gaps 1620 separate the plurality of electrode segments 1610 along a lateral dimension. Specifically, the electrically insulating gaps 1620 separate the plurality of electrode segments 1610 along the y-axis of the display. Each of the electrically insulating gaps 1620 separates the plurality of electrode segments 1610 by an average gap distance equal to or less than about 500 μm, equal to or less than about 300 μm, equal to or less than about 200 μm, equal to or less than about 100 μm, or between about 10 μm and about 100 μm. The plurality of electrode segments 1610 are coplanar and parallel to each other. Multiple electrode segments 1610 can be connected to a circuit chip 1630, wherein the circuit chip 1630 can be configured to apply a drive voltage to one or more of the multiple electrode segments 1610. For example... Figure 16A As shown, the plurality of electrode segments 1610 includes three electrode segments spanning the y-axis of the electronic device and separated by an electrically insulating gap 1620. In some implementations, an example film stacked on top of the plurality of electrode segments 1610 provides electrical connection to a circuit chip 1630 (without circuitry). Figure 12A-12B As shown in 15A-15C.

[0159] Figure 16BA schematic diagram of an example ultrasonic fingerprint sensor system with segmented electrodes employing a "2-D island" design, according to some implementations, is shown. The ultrasonic fingerprint sensor system for an electronic device includes a plurality of electrode segments 1650 having electrically insulating gaps 1660 that space the plurality of electrode segments 1650 apart from each other. The plurality of electrode segments 1650 and the electrically insulating gaps 1660 cover the entire or nearly entire display of the electronic device. The plurality of electrode segments 1650 can be arranged in an array across the display. Specifically, the plurality of electrode segments 1650 can be arranged in an m x n electrode segment array 1650, where m and n are integers. The electrically insulating gaps 1660 separate the plurality of electrode segments 1650 along the lateral dimensions of the display, wherein the lateral dimensions of the display are orthogonal to each other. Specifically, the electrically insulating gaps 1660 separate the plurality of electrode segments 1610 along the y- and x-dimensions of the display. Each of the electrically insulating gaps 1660 separates the plurality of electrode segments 1650 by an average gap distance equal to or less than about 500 μm, equal to or less than about 300 μm, equal to or less than about 200 μm, equal to or less than about 100 μm, or between about 10 μm and about 100 μm. The plurality of electrode segments 1660 are coplanar with each other. A circuit 1670 provides electrical interconnection between the circuit chip 1680 and each of the plurality of electrode segments 1650. Specifically, each of the plurality of electrode segments 1650 is connected to the circuit chip 1680 via discrete wires of the circuit 1670. In this way, the circuit chip 1680 can be configured to drive discrete electrode segments 1650 or sets of discrete electrode segments 1650. Figure 16B As shown, the plurality of electrode segments 1650 includes 12 electrode segments arranged in a 3x4 array and separated by electrically insulating gaps 1660. In some implementations, circuitry providing electrical connections to the plurality of electrode segments 1650 is provided by an example film 1670 stacked on top of... Figures 13A-13B As shown in 14C.

[0160] Figures 17A-17B The diagram illustrates cross-sectional schematics of various stages in an example method for manufacturing an ultrasonic fingerprint sensor system with segmented electrodes of an ultrasonic transceiver employing a "strip" design, according to some implementations. It will be appreciated that methods for manufacturing ultrasonic fingerprint sensor systems may include... Figures 17A-17B The operations shown are fewer, more, or different compared to those shown.

[0161] exist Figure 17AA sensor substrate 1710 is provided. The sensor substrate 1710 may comprise any suitable flexible material (such as polyimide) or any suitable rigid material (such as glass). A piezoelectric layer 1720 may be coupled to the sensor substrate 1710 and disposed above the sensor substrate 1710. The piezoelectric layer 1720 may be used as an ultrasonic transceiver configured to generate and receive ultrasonic waves. An electrode layer 1730 may be coupled to the piezoelectric layer 1720 and disposed above the piezoelectric layer 1720, wherein the electrode layer 1730 may be divided into multiple electrode segments.

[0162] exist Figure 17B In this configuration, a non-conductive layer 1740 is formed over the electrode layer 1730. The non-conductive layer 1740 may cover each electrode segment of the electrode layer 1730 and separate the electrode segments with electrically insulating gaps. In some implementations, where the electrode layer 1730 has sufficient thickness and composition to function as a high acoustic impedance layer, the non-conductive layer 1740 may comprise an electrically insulating material that does not necessarily have high density or high impedance. For example, the electrode layer 1730 may comprise a thick silver ink electrode (e.g., greater than about 10 μm) and the non-conductive layer 1740 may comprise an acrylic coating. In other cases... Figure 16A In the illustrated "strip" design, the electrode segments can be separated by gaps equal to or greater than about 200 μm, about 300 μm, or about 500 μm. In some implementations, when electrode layer 1730 is not used as a high acoustic impedance layer, non-conductive layer 1740 has a high density or high impedance value. For example, electrode layer 1730 may include a thin silver ink electrode (e.g., less than about 10 μm) and non-conductive layer 1740 may include a dielectric material having an acoustic impedance value greater than about 8.0 MRayl.

[0163] Figures 18A-18D The illustration shows cross-sectional schematic diagrams of various stages in an example method for manufacturing an ultrasonic fingerprint sensor system with segmented electrodes of an ultrasonic transceiver employing a "2-D island" design, according to some implementations. It will be appreciated that the method for manufacturing the ultrasonic fingerprint sensor system may include... Figures 18A-18D The operations shown are fewer, more, or different compared to those shown.

[0164] exist Figure 18AA sensor substrate 1810 is provided. The sensor substrate 1810 may comprise any suitable flexible material (such as polyimide) or any suitable rigid material (such as glass). A piezoelectric layer 1820 may be coupled to the sensor substrate 1810 and disposed above the sensor substrate 1810. The piezoelectric layer 1820 may be used as an ultrasonic transceiver configured to generate and receive ultrasonic waves. An electrode layer 1830 may be coupled to the piezoelectric layer 1820 and disposed above the piezoelectric layer 1820, wherein the electrode layer 1830 may be divided into multiple electrode segments. In some implementations, the electrode layer 1830 may comprise a thin conductive material (e.g., between about 5 nm and about 3000 nm) made of copper, aluminum, nickel, or combinations thereof. Figure 16B In the “2-D island” design shown, each electrode segment can be separated by a gap of approximately 300 μm or less, approximately 200 μm or less, approximately 100 μm or less, or between approximately 10 μm and approximately 100 μm.

[0165] exist Figure 18B In this embodiment, an electrically insulating layer 1840 is formed over the electrode layer 1830. In some implementations, the electrically insulating layer 1840 comprises a photoimageable epoxy resin. The photoimageable epoxy resin may be a polymeric material having a curing temperature equal to or lower than about 150°C, equal to or lower than about 140°C, or equal to or lower than about 120°C. For example, the photoimageable epoxy resin may include SU-8. The electrically insulating layer 1840 may have a thickness between about 3 μm and about 15 μm, or between about 5 μm and about 10 μm. The electrically insulating layer 1840 may be patterned to form openings such that at least one of the electrode segments of the electrode layer 1830 may be exposed.

[0166] exist Figure 18C In this structure, a circuit layer 1850 is formed above an electrically insulating layer 1840. The circuit layer 1850 can be formed through the opening to electrically connect with at least one of the electrode segments of the electrode layer 1830. Thus, the circuit layer 1850 fills the opening to contact the electrode layer 1830. In some implementations, the circuit layer 1850 is formed of the same material as the electrode layer 1830. In some implementations, the circuit layer 1850 is formed of a different material than the electrode layer 1830. In some implementations, the circuit layer 1850 has a thickness between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 10 nm and about 1000 nm. The circuit layer 1850 provides routing for multiple electrode segments through a circuit system for driving each of the electrode segments. In this way, the multiple electrode segments of the electrode layer 1830 can be arranged as follows... Figure 16B The “2-D island” design shown is used for segmentation.

[0167] exist Figure 18DIn this embodiment, a non-conductive acoustic layer 1860 is formed above the circuit layer 1850. The non-conductive acoustic layer 1860 may comprise a dielectric material having an acoustic impedance value greater than about 8.0 MRayl. In some implementations, a passivation layer (not shown) may be formed above the non-conductive acoustic layer 1860 to smooth the roughness in the non-conductive acoustic layer 1860. In some implementations, the passivation layer has a thickness between about 10 μm and about 50 μm and has a roughness value equal to or less than about 5 nm (in terms of RMS). In some implementations, the passivation layer may be laminated onto the non-conductive acoustic layer 1860. The electrically insulating layer 1840 may be thick enough to reduce the electrical coupling between the electrode layer 1830 and the circuit layer 1850 and to minimize additional load. However, the electrically insulating layer 1840 may be thin enough to ensure effective acoustic coupling between the non-conductive acoustic layer 1860 and the piezoelectric layer 1820. Accordingly, the separation caused by the thickness of the electrical insulating layer 1840 is not so significant that the high impedance layer (i.e., the non-conductive acoustic layer 1860) is no longer adjacent to the piezoelectric layer 1820, which would otherwise have reduced the signal strength of the ultrasound.

[0168] Figures 19A-19F The diagram illustrates cross-sectional schematics of various stages in an example method for manufacturing an ultrasonic fingerprint sensor system with segmented electrodes employing an ultrasonic transmitter with a "strip" design, according to some implementations. It will be appreciated that the method for manufacturing the ultrasonic fingerprint sensor system may include... Figures 19A-19F The operations shown are fewer, more, or different compared to those shown.

[0169] exist Figure 19A In this embodiment, a carrier substrate 1910 is provided. The carrier substrate 1910 may include any suitable substrate material. An FPC 1920 may be coupled to and disposed above the carrier substrate 1910. The FPC 1920 may include one or more dielectric layers and one or more interconnects (e.g., traces, vias, pads). In some implementations, the FPC 1920 may include a flexible material, such as polyimide. A first electrode layer 1930 may be coupled to and disposed above the FPC 1920. In some implementations, the first electrode layer 1930 may include a thick metal layer (e.g., with a thickness greater than about 10 μm). In some implementations, the first electrode layer 1930 may include silver ink, copper, aluminum, nickel, or combinations thereof. In some implementations, the first electrode layer 1930 may be divided into multiple first electrode segments.

[0170] exist Figure 19B In this configuration, a piezoelectric layer 1940 is formed above the first electrode layer 1930. The piezoelectric layer 1940 can be used as an ultrasonic transmitter configured to generate ultrasonic waves. The first electrode layer 1930 is coupled to and below the piezoelectric layer 1940.

[0171] exist Figure 19CIn this process, the piezoelectric layer 1940 is polarized, and this polarization applies a strong electric field across the piezoelectric layer 1940 so that the electric dipoles in the piezoelectric layer 1940 are oriented in a desired direction.

[0172] exist Figure 19D In this embodiment, a second electrode layer 1950 is formed over the piezoelectric layer 1940. The second electrode layer 1950 is coupled to and covers the piezoelectric layer 1940 such that a metallized electrode can clamp the piezoelectric layer 1940. In some implementations, the second electrode layer 1950 may comprise a thick metal layer (e.g., a thickness greater than about 10 μm) or a thin metal layer (e.g., a thickness less than about 10 μm) accompanied by a high-resistivity layer. In some implementations, the second electrode layer 1950 may comprise silver ink, copper, aluminum, nickel, or a combination thereof. In some implementations, the second electrode layer 1950 may be divided into multiple second electrode segments. The gaps between the multiple second electrode segments may be small or large, as large gaps may not be sufficient to negatively impact image quality in a separate ultrasonic transmitter and ultrasonic receiver implementation. Therefore, the second electrode layer 1950 may comprise a thick silver ink layer. The multiple second electrode segments may correspond to multiple first electrode segments. The multiple second electrode segments and the multiple first electrode segments may be arranged as follows: Figure 16A The "strip" design shown is used for arrangement.

[0173] exist Figure 19E In this embodiment, a non-conductive layer 1960 is formed over the second electrode layer 1950. The non-conductive layer 1960 may also be formed over and around the second electrode layer 1950, the piezoelectric layer 1940, and the first electrode layer 1930. In some implementations, the non-conductive layer 1960 may comprise a dielectric material having a high density or a high impedance value (such as an acoustic impedance value greater than about 8.0 MRayl). In some implementations, the non-conductive layer 1960 need not have a high density or a high impedance value. This may be true in implementations where the second electrode layer 1950 has a high impedance value. For example, the non-conductive layer 1960 may comprise an acrylic coating. In some implementations, the non-conductive layer 1960 may be a backing layer or a passivation layer with a smooth surface, wherein the passivation layer has a thickness between about 10 μm and about 50 μm and has a roughness value equal to or less than about 5 nm (in terms of RMS).

[0174] exist Figure 19F In this process, the carrier substrate 1910 can be removed. The removal of the carrier substrate 1910 forms an ultrasonic transmitter including an FPC 1920, a first electrode layer 1930, a piezoelectric layer 1940, a second electrode layer 1950, and a non-conductive layer 1960. Figure 19F The ultrasonic transmitter can be attached to an ultrasonic transceiver (not shown) to form an ultrasonic fingerprint sensor system.

[0175] Figures 20A-20H The illustration shows cross-sectional schematic diagrams of various stages in an example method for manufacturing an ultrasonic fingerprint sensor system with segmented electrodes employing an ultrasonic transmitter using a "2-D island" design, according to some implementations. It will be appreciated that the method for manufacturing the ultrasonic fingerprint sensor system may include... Figures 20A-20H The operations shown are fewer, more, or different compared to those shown.

[0176] exist Figure 20A A carrier substrate 2010 is provided. The carrier substrate 2010 may include any suitable substrate material. An FPC 2020 may be coupled to and disposed above the carrier substrate 2010. The FPC 2020 may include one or more dielectric layers and one or more interconnects (e.g., traces, vias, pads). In some implementations, the FPC 2020 may include a flexible material, such as polyimide. A first electrode layer 2030 may be coupled to and disposed above the FPC 2020. In some implementations, the first electrode layer 2030 may include a thick metal layer (e.g., with a thickness greater than about 10 μm). In some implementations, the first electrode layer 2030 may include silver ink, copper, aluminum, nickel, or combinations thereof. In some implementations, the first electrode layer 2030 may be continuous and unsegmented.

[0177] exist Figure 20B In this configuration, a piezoelectric layer 2040 is formed above the first electrode layer 2030. The piezoelectric layer 2040 can be used as an ultrasonic transmitter configured to generate ultrasonic waves. The first electrode layer 2030 is coupled to and below the piezoelectric layer 2040. In some implementations, an adhesion promoter (not shown) may be provided to promote adhesion between the first electrode layer 2030 and the piezoelectric layer 2040.

[0178] exist Figure 20C In this process, the piezoelectric layer 2040 is polarized, and this polarization applies a strong electric field across the piezoelectric layer 2040 so that the electric dipoles in the piezoelectric layer 2040 are oriented in a desired direction.

[0179] exist Figure 20DIn this embodiment, a second electrode layer 2050 is formed above the piezoelectric layer 2040. The second electrode layer 2050 is coupled to and covers the piezoelectric layer 2040 such that a metallized electrode can clamp the piezoelectric layer 2040. In some implementations, the second electrode layer 2050 may include a thin metal layer (e.g., less than about 10 μm thick) accompanied by a high-impedance layer. In some implementations, the second electrode layer 2050 may include copper, aluminum, nickel, or a combination thereof. In some implementations, the second electrode layer 2050 has a thickness between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 10 nm and about 1000 nm. In some implementations, the second electrode layer 2050 may be divided into multiple electrode segments. The gaps between the multiple electrode segments may be small or large, as large gaps may not be sufficient to negatively impact image quality in a separate ultrasonic transmitter and ultrasonic receiver implementation. The multiple electrode segments may be arranged in a manner as follows: Figure 16B The “2-D island” design shown is used for segmentation.

[0180] exist Figure 20E In this embodiment, an electrically insulating layer 2060 is formed over the second electrode layer 2050. In some implementations, the electrically insulating layer 2060 comprises a photoimageable epoxy resin. The photoimageable epoxy resin may be a polymeric material having a curing temperature equal to or lower than about 150°C, equal to or lower than about 140°C, or equal to or lower than about 120°C. For example, the photoimageable epoxy resin may include SU-8. The electrically insulating layer 2060 may have a thickness between about 3 μm and about 15 μm, or between about 5 μm and about 10 μm. The electrically insulating layer 2060 may be patterned to form openings such that at least one of the electrode segments of the second electrode layer 2050 may be exposed.

[0181] exist Figure 20F In this configuration, a circuit layer 2070 is formed above an electrically insulating layer 2060. The circuit layer 2070 can be formed through the opening to electrically connect with at least one of the electrode segments of the second electrode layer 2050. Thus, the circuit layer 2070 fills the opening to contact the second electrode layer 2050. In some implementations, the circuit layer 2070 is formed of the same material as the second electrode layer 2050. In some implementations, the circuit layer 2070 is formed of a different material than the second electrode layer 2050. In some implementations, the circuit layer 2070 has a thickness between about 5 nm and about 3000 nm, between about 10 nm and about 2000 nm, or between about 10 nm and about 1000 nm. The circuit layer 2070 provides routing for multiple electrode segments through a circuit system for driving each of the electrode segments. In this way, the multiple electrode segments of the second electrode layer 2050 can be arranged as follows... Figure 16B The “2-D island” design shown is used for segmentation.

[0182] exist Figure 20G In this embodiment, a non-conductive acoustic layer 2080 is formed above the circuit layer 2070. The non-conductive acoustic layer 2080 may comprise a dielectric material having an acoustic impedance value greater than about 8.0 MRayl. In some implementations, a passivation layer (not shown) may be formed above the non-conductive acoustic layer 2080 to smooth the roughness in the non-conductive acoustic layer 2080. In some implementations, the passivation layer has a thickness between about 10 μm and about 50 μm and has a roughness value equal to or less than about 5 nm (in terms of RMS). In some implementations, the passivation layer may be laminated onto the non-conductive acoustic layer 2080. The electrically insulating layer 2060 may be thick enough to reduce the electrical coupling between the second electrode layer 2050 and the circuit layer 2070 and to minimize additional load. However, the electrically insulating layer 2060 may be thin enough to ensure effective acoustic coupling between the non-conductive acoustic layer 2080 and the piezoelectric layer 2040. Therefore, the separation caused by the thickness of the electrical insulating layer 2060 is not so significant that the high impedance layer (i.e., the non-conductive acoustic layer 2080) is no longer adjacent to the piezoelectric layer 2040, which would otherwise have reduced the signal strength of the ultrasonic waves.

[0183] exist Figure 20H In the process, the carrier substrate 2010 can be removed. The removal of the carrier substrate 2010 forms an ultrasonic transmitter including an FPC 2020, a first electrode layer 2030, a piezoelectric layer 2040, a second electrode layer 2050, an electrically insulating layer 2060, a circuit layer 2070, and a non-conductive acoustic layer 2080. Figure 20H The ultrasonic transmitter can be attached to an ultrasonic transceiver (not shown) to form an ultrasonic fingerprint sensor system.

[0184] As used in this article, the phrase “at least one” referring to a list of items means any combination of those items, including a single member. As an example, “at least one of a, b, or c” is intended to cover: a, b, c, ab, ac, bc, and abc.

[0185] The various descriptive logics, logic blocks, modules, circuits, and algorithmic processes described in conjunction with the implementations disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. This interchangeability between hardware and software has been generally described in its functional form and is explained in the various descriptive components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0186] Hardware and data processing means for implementing the various descriptive logics, logic blocks, modules, and circuits described in conjunction with the aspects disclosed herein may be implemented or executed using a general-purpose single-chip or multi-chip processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. A general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration. In some implementations, specific processes and methods may be executed by a circuit system dedicated to a given function.

[0187] In one or more aspects, the described functionality can be implemented in hardware, digital electronic circuit systems, computer software, firmware, the structures disclosed in this specification and their equivalents, or any combination thereof. Implementation of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a computer storage medium for execution by a data processing apparatus or for controlling the operation of a data processing apparatus.

[0188] If implemented in software, the functions can be stored or transmitted as one or more instructions or codes on or through a computer-readable medium (such as a non-transient medium). The processes of the methods or algorithms disclosed herein can be implemented in a processor-executable software module that can reside on a computer-readable medium. Computer-readable media include both computer storage media and communication media, including any medium that can be implemented to transfer a computer program from one location to another. Storage media can be any available medium accessible to a computer. By way of example, but not limitation, non-transient media can include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and is accessible to a computer. Furthermore, any connection can also be aptly referred to as a computer-readable medium. As used herein, disk and disc include compact discs (CDs), laser discs, optical discs, digital multi-purpose discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs optically using lasers. The above combinations should also be included within the scope of computer-readable media. Furthermore, the operation of a method or algorithm may reside as one of code and instructions, or any combination or set of code and instructions, on machine-readable and computer-readable media that can be incorporated into a computer program product.

[0189] Various modifications to the implementations described in this disclosure may be apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the implementations shown herein, but should be granted the broadest scope consistent with the claims, the principles disclosed herein, and the novel features.

[0190] Some features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented separately or in any suitable sub-combination in multiple implementations. Furthermore, although features may be described above as operating in certain combinations and even originally claimed in this way, one or more features from the claimed combination may be removed from that combination in some cases, and the claimed combination may be for sub-combinations or variations thereof.

[0191] Similarly, although the operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring such operations to be performed in the specific order shown or in sequential order, or requiring the execution of all described operations to achieve the desired result. In some environments, multitasking and parallel processing may be advantageous. Furthermore, the separation of the various system components in the implementations described above should not be construed as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations also fall within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired result.

[0192] It will be understood that, unless features in any particular described implementation are explicitly identified as incompatible with each other, or the surrounding context suggests that they are mutually exclusive and not easily combined in a complementary and / or supporting sense, this disclosure generally contemplates and envisions that specific features of those complementary implementations may be selectively combined to provide one or more comprehensive but slightly different technical solutions. Therefore, it will be further appreciated that the above description is given by way of example only and may be modified in detail within the scope of this disclosure.

Claims

1. An ultrasonic fingerprint sensor system, comprising: Sensor substrate; Multiple sensor circuits directly on the sensor substrate; as well as An ultrasonic transceiver coupled to the sensor substrate, wherein the ultrasonic transceiver includes: A piezoelectric layer coupled to the sensor substrate, the piezoelectric layer being configured to generate ultrasonic waves; A non-conductive high acoustic impedance layer is provided adjacent to the piezoelectric layer, wherein the non-conductive high acoustic impedance layer is disposed on the side of the sensor substrate opposite to the display, the ultrasonic fingerprint sensor system is configured to be attached to the display, and wherein the non-conductive high acoustic impedance layer comprises a dielectric material having an acoustic impedance value greater than 8.0 MRayl; and One or more conductive layers exist between the piezoelectric layer and the non-conductive high acoustic impedance layer, and between the non-conductive high acoustic impedance layer and the plurality of sensor circuits, wherein the thickness of the non-conductive high acoustic impedance layer is at least twice the thickness of each of the one or more conductive layers. The one or more conductive layers include an electrode layer beneath the piezoelectric layer, the one or more conductive layers further include a routing layer adjacent to the electrode layer, the ultrasonic transceiver further includes an electrically insulating layer between the electrode layer and the routing layer, and the thickness of the electrically insulating layer is designed to reduce the electrical coupling between the electrode layer and the routing layer and to minimize additional load, and to ensure acoustic coupling between the non-conductive high acoustic impedance layer and the piezoelectric layer.

2. The ultrasonic fingerprint sensor system of claim 1, wherein the electrode layer comprises a plurality of electrode segments.

3. The ultrasonic fingerprint sensor system of claim 2, wherein the average gap distance between adjacent segments of the plurality of electrode segments is equal to or less than 200 μm.

4. The ultrasonic fingerprint sensor system of claim 2, wherein the plurality of electrode segments are arranged as strips having electrically insulating gaps that separate the plurality of electrode segments along the lateral dimension of the ultrasonic fingerprint sensor system.

5. The ultrasonic fingerprint sensor system of claim 1, wherein the electrical insulating layer comprises a photoimageable epoxy resin.

6. The ultrasonic fingerprint sensor system of claim 2, wherein the plurality of electrode segments are arranged as a 2-D island array, the 2-D island array having electrically insulating gaps separating the 2-D islands along lateral dimensions orthogonal to each other in the ultrasonic fingerprint sensor system.

7. The ultrasonic fingerprint sensor system of claim 1, wherein the thickness of each of the one or more conductive layers is between 10 nm and 2 μm.

8. The ultrasonic fingerprint sensor system of claim 7, wherein each of the one or more conductive layers comprises aluminum, nickel, copper, or a combination thereof.

9. The ultrasonic fingerprint sensor system of claim 1, wherein the non-conductive high acoustic impedance layer has a density of 3500 to 10000 kg / m². 3 The density between.

10. The ultrasonic fingerprint sensor system of claim 1, wherein the substrate is a rigid substrate.

11. An ultrasonic fingerprint sensor system, comprising: Sensor substrate; Multiple sensor circuits directly on the sensor substrate; as well as An ultrasonic transmitter, wherein the ultrasonic transmitter comprises: A piezoelectric emitter layer configured to generate ultrasonic waves; A non-conductive high acoustic impedance layer is provided, adjacent to the piezoelectric emitter layer, wherein the non-conductive high acoustic impedance layer is positioned on the side of the sensor substrate opposite to the display, the ultrasonic fingerprint sensor system is configured to be attached to the display, and wherein the non-conductive high acoustic impedance layer comprises a dielectric material having an acoustic impedance value greater than 8.0 MRayl; and A first conductive layer, situated between the non-conductive high acoustic impedance layer and the piezoelectric emitter layer, wherein the thickness of the non-conductive high acoustic impedance layer is at least twice the thickness of the first conductive layer; and An ultrasonic receiver, wherein the ultrasonic receiver includes a piezoelectric receiver layer configured to receive reflections of the ultrasonic waves. The first conductive layer includes an electrode layer below the piezoelectric transmitter layer, wherein the first conductive layer further includes a routing layer adjacent to the electrode layer, wherein the ultrasonic transmitter further includes an electrically insulating layer between the electrode layer and the routing layer, and wherein the thickness of the electrically insulating layer is designed to reduce the electrical coupling between the electrode layer and the routing layer and to minimize additional load, and to ensure acoustic coupling between the non-conductive high acoustic impedance layer and the piezoelectric transmitter layer.

12. The ultrasonic fingerprint sensor system of claim 11, wherein the first conductive layer comprises a plurality of electrode segments.

13. The ultrasonic fingerprint sensor system of claim 11, wherein the ultrasonic transmitter further comprises: A second conductive layer on the side of the piezoelectric emitter layer opposite to the first conductive layer.

14. The ultrasonic fingerprint sensor system of claim 13, wherein the second conductive layer comprises a plurality of electrode segments and the first conductive layer spans continuously across the ultrasonic transmitter, wherein the second conductive layer has a thickness greater than the thickness of the first conductive layer.

15. The ultrasonic fingerprint sensor system of claim 11, wherein the ultrasonic receiver further comprises: An electrode layer on the piezoelectric receiver layer, wherein the electrode layer spans continuously across the ultrasonic receiver.

16. The ultrasonic fingerprint sensor system of claim 11, wherein the thickness of the first conductive layer is between 10 nm and 2 μm.

17. The ultrasonic fingerprint sensor system of claim 11, wherein the first conductive layer comprises aluminum, nickel, copper, or a combination thereof.

18. The ultrasonic fingerprint sensor system of claim 11, wherein the non-conductive high acoustic impedance layer has a density of 3500 to 10000 kg / m². 3 The density between.

19. The ultrasonic fingerprint sensor system of claim 11, wherein the substrate is a rigid substrate, wherein the ultrasonic receiver is above the substrate and the ultrasonic transmitter is below the substrate, wherein the non-conductive high acoustic impedance layer is between the piezoelectric transmitter layer and the substrate.

20. The ultrasonic fingerprint sensor system of claim 11, wherein the substrate is a flexible substrate, wherein the ultrasonic receiver is above the substrate and the ultrasonic transmitter is above the ultrasonic receiver, wherein the non-conductive high acoustic impedance layer is above the piezoelectric transmitter layer.

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