WO2017205656A1

WO2017205656A1 - Capacitive fingerprint sensor with glass substrate

Info

Publication number: WO2017205656A1
Application number: PCT/US2017/034529
Authority: WO
Inventors: Jason Goodelle; Stephen L. Morein; Jeffrey S. Lillie; Frank Schwab; Bob Lee Mackey
Original assignee: Synaptics Incorporated
Priority date: 2016-05-25
Filing date: 2017-05-25
Publication date: 2017-11-30

Abstract

A method for manufacturing fingerprint sensor packages having glass substrates includes: providing a glass panel; forming conductive and dielectric layers onto the glass panel, wherein forming the conductive and dielectric layers includes patterning a plurality of capacitive sensor arrays for the fingerprint sensor packages; attaching a plurality of fingerprint sensor chips to respective conductors of the conductive and dielectric layers on the same side of the glass panel as the plurality of conductive and dielectric layers; forming a protective layer over the capacitive sensor arrays; and performing singulation to form individual fingerprint sensor packages.

Description

CAPACITIVE FINGERPRINT SENSOR WITH GLASS SUBSTRATE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claim the benefit of U.S. Provisional Patent Application No. 62/341,599, filed May 25, 2016, which is incorporated by reference herein in its entirety.

BACKGROUND

[0002] Fingerprint sensors are widely used in a variety of electronic systems. Fingerprint sensors typically include a sensing region, often demarked by a surface, via which a fingerprint sensor device determines presence, location, motion, and/or features of a fingerprint or partial fingerprint, typically for purposes relating to user authentication or identification of a user.

[0003] Fingerprint sensors may thus be used to provide interfaces for the electronic system. For example, fingerprint sensors are often used as an input interface for larger computing systems (e.g., in the form of fingerprint readers integrated in or peripheral to notebook or desktop computers). Fingerprint sensors are also often used in smaller computing systems (e.g., in the form of fingerprint readers integrated in mobile devices such as smartphones and tablets).

[0004] Object imaging, such as fingerprint sensing, is useful in a variety of applications. By way of example, biometric recognition systems image biometric objects for authenticating and/or verifying users of devices incorporating the recognition systems. Biometric imaging provides a reliable, non-intrusive way to verify individual identity for recognition purposes.

[0005] Various types of sensors may be used for biometric imaging, including, for example, fingerprint sensors. Fingerprints, like various other biometric characteristics, are based on distinctive personal characteristics and thus provide a reliable mechanism to recognize an individual. Thus, fingerprint sensors have many potential applications. For example, fingerprint sensors may be used to provide access control in stationary applications, such as security checkpoints. Fingerprint sensors may also be used to provide access control in mobile devices, such as cell phones, wearable smart devices (e.g., smart watches and activity trackers), tablet computers, personal data assistants (PDAs), navigation devices, and portable gaming devices.

[0006] Current capacitive fingerprint sensor devices often use either: (1) a plastic ball grid array (PBGA) substrate within which transmitter and receiver sensor traces are located on the top two layers of a multi-layer substrate, or (2) a chip attached to a flexible circuit within which the sensor traces are disposed. The PBGA substrate sensor design utilizes at least two build up layers on either side of a copper clad core, typically called a multi-layer substrate. Multiple layer substrates can be formed by laminating multiple cores together and repeating the previous steps. Also, multiple conductor layers can be built up on a single drilled core by successively laminating dielectric, drilling micro vias (usually laser), plating metal, and etching conductor patterns. This process is called a build-up process. Existing build-up processes become limited in terms of yield and process control below 15 um lines / 30 um spaces rules. Also, the trace morphology is strongly influenced by the topography (smoothness) of the underlying dielectric, and the thickness and conductor cross-section become very difficult to control using standard plating and wet etch processes common to the build-up substrate process flow. Forming the sensor traces within a flexible circuit configuration is subject to manufacturing tolerances and constraints similar to those of the build-up PBGA substrate configuration.

[0007] Further, for current capacitive fingerprint sensor devices, there is an issue of warpage present in many integrated circuit (IC) packages induced by attaching a silicon chip having a low coefficient of thermal expansion (CTE) to a higher CTE organic carrier (typically done at an elevated temperature). This becomes a significant issue in terms of yield and performance control.

SUMMARY

[0008] In an exemplary embodiment, a method for manufacturing fingerprint sensor packages having glass substrates includes: providing a glass panel; forming conductive and dielectric layers onto the glass panel, wherein forming the conductive and dielectric layers includes patterning a plurality of capacitive sensor arrays for the fingerprint sensor packages; attaching a plurality of fingerprint sensor chips to respective conductors of the conductive and dielectric layers on the same side of the glass panel as the plurality of conductive and dielectric layers; forming a protective layer over the capacitive sensor arrays; and performing singulation to form individual fingerprint sensor packages.

[0009] In another exemplary embodiment, a fingerprint sensor package includes: a glass substrate; conductive and dielectric layers disposed on the glass substrate, wherein the conductive and dielectric layers comprise a capacitive sensor array; a fingerprint sensor chip attached to respective conductors of the conductive and dielectric layers, wherein the fingerprint sensor chip is disposed on the same side of the glass substrate as the conductive and dielectric layers; and a protective layer, disposed over the capacitive sensor array.

[0010] In yet another exemplary embodiment, an electronic device includes a display, a processor, and a fingerprint sensor package. The processor is configured to cause the display to prompt a user for biometric authentication. The fingerprint sensor package includes: a glass substrate; conductive and dielectric layers disposed on the glass substrate, wherein the conductive and dielectric layers comprise a capacitive sensor array; a fingerprint sensor chip attached to respective conductors of the conductive and dielectric layers, wherein the fingerprint sensor chip is disposed on the same side of the glass substrate as the conductive and dielectric layers; a protective layer, disposed over the capacitive sensor array; and a flex, attached to respective conductors of the conductive and dielectric layers, configured to facilitate communication between the fingerprint sensor chip and the processor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a block diagram of an example input device.

[0012] FIG. 2 is a schematic block diagram of a further example input device.

[0013] FIG. 3 is a schematic diagram of an electronic device.

[0014] FIG. 4 is a schematic flowchart depicting exemplary processing steps for manufacturing fingerprint sensor packages on a glass substrate.

[0015] FIG. 5 is a schematic flowchart depicting further exemplary processing steps for manufacturing fingerprint sensor packages on a glass substrate, including formation of a protective layer.

[0016] FIGS. 6A-6C are schematic block diagrams depicting cross-sections of exemplary fingerprint sensor packages in accordance with some exemplary embodiments.

[0017] FIGS. 7A-7B are schematic block diagrams depicting cross-sections of exemplary fingerprint sensor packages in accordance with some other exemplary embodiments.

[0018] FIG. 8 is a schematic block diagram depicting a cross-section of an exemplary fingerprint sensor package in accordance with another exemplary embodiment.

[0019] FIG. 9 is a schematic block diagram depicting a top-down view of an exemplary fingerprint sensor package in accordance with an exemplary embodiment. DETAILED DESCRIPTION

[0020] The following detailed description is exemplary in nature and is not intended to limit the disclosure or the application and uses of the disclosure. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding background, summary and brief description of the drawings, or the following detailed description.

[0021] Sensor performance and yield for ball grid array (BGA) fingerprint sensor packages is tied to the minimum pitch, thickness and width tolerance, as well as process control, for the sensor traces. Considering the limitations of existing BGA substrate processing technology for capacitive fingerprint sensor devices, exemplary embodiments described herein provide enhanced yield, cost and performance relative to current capacitive fingerprint sensor devices by utilizing an alternate approach for creating the fingerprint sensor package. In particular, exemplary embodiments utilize thin film metallization techniques (e.g., sputtering / evaporative deposition) and highly -accurate dry etch processes to fabricate fingerprint sensors on a glass substrate, such that the very well-controlled processes typically found in silicon wafer fabs or liquid crystal display manufacturing lines (LCMs) and highly-accurate dry etch processes can be applied to the manufacture of capacitive fingerprint sensors.

[0022] By utilizing a glass substrate together with such fabrication techniques, exemplary embodiments are able to achieve numerous advantages over current capacitive fingerprint sensor configurations, particularly with respect to improving sensor yield at relatively lower cost. A large number of sensors may be manufactured very cost-effectively on glass panels that are, for example, hundreds of thousands of square millimeters in starting size, which are then cut to a final size used in particular application (e.g., typically less than 100mm²). Further, "fab level" control may be utilized with respect to metal and dielectric processing while decoupling the size of the silicon from the size of the sensor, which avoids an inherent disadvantage of "on chip" sensor fabrication. For example, by using a glass (or silicon) interposer substrate for manufacturing the sensor pattern, relatively aggressive technology nodes (e.g., 55nm or below) may be used to shrink the die size while keeping the sensor appropriately sized for the application.

[0023] Thus, exemplary embodiments provide for using chip-on-glass substrate technology, including thin film and fab metal / dielectric processing, to fabricate fingerprint sensor packages. By utilizing this low-cost and existing infrastructure, cost-effective fingerprint sensor packages can be manufactured using cost-effective glass substrates without needing to use expensive via-in-glass technology. The fingerprint sensor packages can then be readily incorporated into various types of end devices.

[0024] Before getting into particular details of some particular exemplary embodiments, general exemplary environments are discussed below in connection with FIGS. 1-3 to provide context. It will be appreciated that the described environments of FIGS. 1-3 are exemplary, and that the principles discussed herein are not limited thereto.

[0025] FIG. 1 is a block diagram depicting an example input device 100. The input device 100 may be configured to provide input to an electronic system. As used in this document, the term "electronic system" (or "electronic device") broadly refers to any system capable of electronically processing information. Some non-limiting examples of electronic systems include personal computers of all sizes and shapes, such as desktop computers, laptop computers, netbook computers, tablets, web browsers, e-book readers, personal digital assistants (PDAs), and wearable computers (such as smart watches and activity tracker devices). Additional examples of electronic systems include composite input devices, such as physical keyboards that include input device 100 and separate joysticks or key switches. Further examples of electronic systems include peripherals such as data input devices (including remote controls and mice), and data output devices (including display screens and printers). Other examples include remote terminals, kiosks, and video game machines (e.g., video game consoles, portable gaming devices, and the like). Other examples include communication devices (including cellular phones, such as smart phones), and media devices (including recorders, editors, and players such as televisions, set-top boxes, music players, digital photo frames, and digital cameras). Additionally, the electronic system may be a host or a slave to the input device.

[0026] The input device 100 can be implemented as a physical part of the electronic system, or can be physically separate from the electronic system. As appropriate, the input device 100 may communicate with parts of the electronic system using any one or more of the following: buses, networks, and other wired or wireless interconnections. Examples include Inter-Integrated Circuit (I2C), Serial Peripheral Interface (SPI), Personal System/2 (PS/2), Universal Serial Bus (USB), Bluetooth, radio frequency (RF), and Infrared Data Association (IRDA).

[0027] In FIG. 1, a fingerprint sensor 105 is included with the input device 100. The fingerprint sensor 105 comprises one or more sensing elements configured to sense input provided by one or more input objects in a sensing region. The sensing region encompasses any space above, around, in and/or near the fingerprint sensor 105 in which the input device 100 is able to detect user input (e.g., user input provided by one or more input objects). The sizes, shapes, and locations of particular sensing regions may vary from embodiment to embodiment. In some embodiments, the sensing region extends from a surface of the input device 100 in one or more directions into space until signal-to-noise ratios prevent sufficiently accurate object detection. The distance to which this sensing region extends in a particular direction, in various embodiments, may be on the order of less than a millimeter, millimeters, centimeters, or more, and may vary significantly with the accuracy desired. Thus, some embodiments sense input that comprises no contact with any surfaces of the input device 100, contact with an input surface (e.g., a touch surface) of the input device 100, contact with an input surface of the input device 100 coupled with some amount of applied force or pressure, and/or a combination thereof. In various embodiments, input surfaces may be provided by surfaces of sensor substrates within which or on which sensor elements are positioned, or by face sheets or other cover layers positioned over sensor elements.

[0028] The input device 100 comprises one or more sensing elements for detecting user input. Some implementations utilize arrays or other regular or irregular patterns of sensing elements to detect the input object. The input device 100 may utilize different combinations of sensor components and sensing technologies to detect user input in the sensing region.

[0029] The input device 100 is a capacitive input device. Voltage or current is applied to create an electric field. Nearby input objects cause changes in the electric field, and produce detectable changes in capacitive coupling that may be detected as changes in voltage, current, or the like.

[0030] Some implementations utilize arrays or other regular or irregular patterns of capacitive sensing elements to create electric fields. In some implementations, separate sensing elements may be ohmically shorted together to form larger sensor electrodes. Some implementations utilize resistive sheets, which may be uniformly resistive.

[0031] Some implementations utilize "self capacitance" (or "absolute capacitance") sensing methods based on changes in the capacitive coupling between sensor electrodes and an input object. In various embodiments, an input object near the sensor electrodes alters the electric field near the sensor electrodes, thus changing the measured capacitive coupling. In one implementation, an absolute capacitance sensing method operates by modulating sensor electrodes with respect to a reference voltage (e.g. system ground), and by detecting the capacitive coupling between the sensor electrodes and input obj ects. In another

implementation, an absolute capacitance sensing method operates by modulating a drive ring or other conductive element that is ohmically or capacitively coupled to the input object, and by detecting the resulting capacitive coupling between the sensor electrodes and the input object. The reference voltage may by a substantially constant voltage or a varying voltage and in various embodiments; the reference voltage may be system ground.

[0032] Some implementations utilize "mutual capacitance" (or "transcapacitance") sensing methods based on changes in the capacitive coupling between sensor electrodes. In various embodiments, an input object near the sensor electrodes alters the electric field between the sensor electrodes, thus changing the measured capacitive coupling. In one implementation, a transcapacitive sensing method operates by detecting the capacitive coupling between one or more transmitter sensor electrodes (also "transmitter electrodes" or "drive electrodes") and one or more receiver sensor electrodes (also "receiver electrodes" or "pickup electrodes"). Transmitter sensor electrodes may be modulated relative to a reference voltage to transmit transmitter signals. Receiver sensor electrodes may be held substantially constant relative to the reference voltage to facilitate receipt of resulting signals. The reference voltage may be, for example, a substantially constant voltage or system ground. In some embodiments, transmitter sensor electrodes and receiver sensor electrodes may both be modulated. The transmitter electrodes are modulated relative to the receiver electrodes to transmit transmitter signals and to facilitate receipt of resulting signals. A resulting signal may comprise effect(s) corresponding to one or more transmitter signals, and/or to one or more sources of environmental interference (e.g. other electromagnetic signals). Sensor electrodes may be dedicated transmitters or receivers, or may be configured to both transmit and receive.

[0033] Some implementations of the input device 100 are configured to provide images that span one, two, three, or higher dimensional spaces. The input device 100 may have a sensor resolution that varies from embodiment to embodiment depending on factors such as the scale of information of interest. In some embodiments, the sensor resolution is determined by the physical arrangement of an array of sensing elements, where smaller sensing elements and/or a smaller pitch can be used to define a higher sensor resolution.

[0034] The input device 100 is implemented as a fingerprint sensor device having a sensor resolution high enough to capture discriminative features of a fingerprint. In some implementations, the fingerprint sensor has a resolution sufficient to capture minutia (including ridge endings and bifurcations), orientation fields (sometimes referred to as "ridge flows"), and/or ridge skeletons. These are sometimes referred to as level 1 and level 2 features, and in an exemplary embodiment, a resolution of at least 250 pixels per inch (ppi) is capable of reliably capturing these features. In some implementations, the fingerprint sensor has a resolution sufficient to capture higher level features, such as sweat pores or edge contours (i.e., shapes of the edges of individual ridges). These are sometimes referred to as level 3 features, and in an exemplary embodiment, a resolution of at least 750 pixels per inch (ppi) is capable of reliably capturing these higher level features.

[0035] In some embodiments, a fingerprint sensor is implemented as a placement sensor (also "area" sensor or "static" sensor) or a swipe sensor (also "slide" sensor or "sweep" sensor). In a placement sensor implementation, the sensor is configured to capture a fingerprint input as the user's finger is held stationary over the sensing region. Typically, the placement sensor includes a two-dimensional array of sensing elements capable of capturing a desired area of the fingerprint in a single frame. In a swipe sensor implementation, the sensor is configured to capture to a fingerprint input based on relative movement between the user's finger and the sensing region. Typically, the swipe sensor includes a linear array or a thin two-dimensional array of sensing elements configured to capture multiple frames as the user's finger is swiped over the sensing region. The multiple frames may then be

reconstructed to form an image of the fingerprint corresponding to the fingerprint input. In some implementations, the sensor is configured to capture both placement and swipe inputs.

[0036] In some embodiments, a fingerprint sensor is configured to capture less than a full area of a user's fingerprint in a single user input (referred to herein as a "partial" fingerprint sensor). Typically, the resulting partial area of the fingerprint captured by the partial fingerprint sensor is sufficient for the system to perform fingerprint matching from a single user input of the fingerprint (e.g., a single finger placement or a single finger swipe). Some exemplary imaging areas for partial placement sensors include an imaging area of 100 mm² or less. In another exemplary embodiment, a partial placement sensor has an imaging area in the range of 20-50 mm². In some implementations, the partial fingerprint sensor has an input surface that is the same size the imaging area.

[0037] In FIG. 1, a processing system 1 10 is included with the input device 100. The processing system 110 comprises parts of or all of one or more integrated circuits (ICs) and/or other circuitry components. The processing system 110 is coupled to the fingerprint sensor 105, and is configured to detect input in the sensing region using sensing hardware of the fingerprint sensor 105.

[0038] The processing system 1 10 may include driver circuitry configured to drive sensing signals with sensing hardware of the input device 100 and/or receiver circuitry configured to receive resulting signals with the sensing hardware. For example, a processing system for a mutual capacitance sensor device may be configured to drive transmit signals onto transmitter sensor electrodes of the fingerprint sensor 105, and/or receive resulting signals detected via receiver sensor electrodes of the fingerprint sensor 105. Further, a processing system for a self capacitance sensor device may be configured to drive absolute capacitance signals onto sensor electrodes of the fingerprint sensor 105, and/or receive resulting signals detected via those sensor electrodes of the fingerprint sensor 105.

[0039] The processing system 110 may include processor-readable instructions, such as firmware code, software code, and/or the like. The processing system 110 can be integrated with the fingerprint sensor 105 (e.g., the processing system 1 10 may be a fingerprint sensor chip and the fingerprint sensor 105 may be a capacitive sensor array, both of which are part of a fingerprint sensor package), or can be physically separate from the fingerprint sensor 105. Also, constituent components of the processing system 110 may be located together, or may be located physically separate from each other. For example, the input device 100 may be a peripheral coupled to a computing device, and the processing system 1 10 may comprise software configured to run on a central processing unit of the computing device and one or more ICs (e.g., with associated firmware) separate from the central processing unit. As another example, the input device 100 may be physically integrated in a mobile device, and the processing system 1 10 may comprise circuits and firmware that are part of a main processor of the mobile device. The processing system 110 may be dedicated to

implementing the input device 100, or may perform other functions, such as operating display screens, driving haptic actuators, etc.

[0040] The processing system 1 10 may operate the sensing element(s) of the fingerprint sensor 105 of the input device 100 to produce electrical signals indicative of input (or lack of input) in a sensing region. The processing system 1 10 may perform any appropriate amount of processing on the electrical signals in producing the information provided to the electronic system. For example, the processing system 1 10 may digitize analog electrical signals obtained from the sensor electrodes. As another example, the processing system 110 may perform filtering or other signal conditioning. As yet another example, the processing system 110 may subtract or otherwise account for a baseline, such that the information reflects a difference between the electrical signals and the baseline. As yet further examples, the processing system 110 may determine positional information, recognize inputs as commands, recognize handwriting, match biometric samples, and the like.

[0041] The electronic system may include a display device. The display device may be any suitable type of dynamic display capable of displaying a visual interface to a user, including an inorganic light-emitting diode (LED) display, organic LED (OLED) display, cathode ray tube (CRT), liquid crystal display (LCD), plasma display, electroluminescence (EL) display, or other display technology. The display may be flexible or rigid, and may be flat, curved, or have other geometries. The display may include a glass or plastic substrate for thin-film transistor (TFT) circuitry, which may be used to address display pixels for providing visual information and/or providing other functionality. The display device may include a cover lens (sometimes referred to as a "cover glass") disposed above display circuitry and above inner layers of the display module, and the cover lens may also provide an input surface for the input device 100. Examples of cover lens materials include optically clear amorphous solids, such as chemically hardened glass, and optically clear crystalline structures, such as sapphire. The input device 100 and the display device may share physical elements. For example, the display screen may be operated in part or in total by the processing system 110 in communication with the input device.

[0042] FIGS. 2 is a block diagram depicting a further exemplary input device. In FIG. 2, the input device 200 is shown as including a fingerprint sensor 205. The fingerprint sensor 205 is configured to capture a fingerprint from a finger 240. The fingerprint sensor 205 is disposed underneath a cover layer 212 that provides an input surface for the fingerprint to be placed on or swiped over the fingerprint sensor 205. The sensing region 220 may include an input surface with an area larger than, smaller than, or similar in size to a full fingerprint. The fingerprint sensor 205 has an array of sensing elements with a resolution configured to detect surface variations of the finger 240. The fingerprint sensor 205 is connected to a processing system 210, which drives the fingerprint sensor 205 and processes signals detected by the fingerprint sensor 205.

[0043] FIG. 3 is a schematic diagram illustrating an example electronic device 301 (e.g., a mobile device, such as a smartphone or tablet) having both a fingerprint sensing interface 305 of a fingerprint sensor package and a display 302. As can be seen in FIG. 3, the fingerprint sensing interface 305 of the fingerprint sensor package is separate from the active display area of the display 302. The electronic device 301 may further comprise a processor configured to cause the display 302 to prompt a user for biometric authentication and to communicate with the fingerprint sensor package.

[0044] FIG. 4 is a schematic flowchart depicting exemplary processing steps for manufacturing fingerprint sensor packages on a glass substrate in accordance with an exemplary embodiment. At stage 401 , the process begins with a large glass panel as a glass substrate for the multiple fingerprint sensor packages that are to be manufactured. The glass panel may be, for example, made of solid glass material with thickness up to 500um, similar to the types of glass panels used in liquid crystal displays (LCDs). In an exemplary implementation, borosilicate glass having a CTE of 3.0ppm may be used, which is very well- matched to silicon, so as to avoid warpage due to CTE-driven mechanics. The glass panel may be of a size that is easily handled by generation 1 or above liquid crystal display (LCD) manufacturing equipment. Table 1 below provides examples of typical glass panel starting sizes for various generations of LCD manufacturing equipment.

Table 1

[0045] At stage 402, conductive and dielectric layers are deposited onto the glass panel for the fingerprint sensor packages. The conductive layers may be patterned through conductive layer depositions (e.g., via sputtering, plating, and/or evaporation), followed by pattern etching (e.g., using photoimageable mask layers). Dielectric layers may be deposited either by using techniques such as plasma-enhanced chemical vapor deposition for inorganic silicon dioxide layers or by using printed glass or polymers. The process technology used in stage 402 may be based on techniques and equipment that are typically used in wafer fabs and/or LCMs for the production of liquid crystal displays. The dielectric material used for the dielectric layers may be, for example, silicon dioxide, silicon nitride, polyimide or other spin on polymer materials. The conductive material used for the conductive layers may be, for example, aluminum, copper, indium tin oxide (ITO), or other metal materials. [0046] In an exemplary implementation, patterning a conductive layer, followed by depositing a dielectric layer, may include: 1) depositing a blanket layer of a conductive material (e.g., via chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), sputtering, etc.); 2) applying a layer of photoresist onto the conductive material; 3) developing the photoresist using a photo mask (e.g., via a contact mask or stepper technology); 4) etching to form conductor patterns in the conductive material, 5) removing the remaining photo resist; and 6) depositing a layer of dielectric onto the patterned conductive material. Steps 1) through 5) may then be repeated to form a second layer of patterned conductors (e.g., with the first layer of conductors corresponding to a first type of electrodes (such as transmitter electrodes) and the second layer of patterned conductors corresponding to a second type of electrodes (such as receiver electrodes). Step 6) may be repeated to form additional dielectric layers as well. Masking and etching may also be performed in the dielectric layers between conductive layers to open holes between the conductive layers that are subsequently filled with conductive material in a further conductor deposition process, so as to form connections between the conductive layers commonly known as vias. Typical conductive and dielectric layer thicknesses are ~lum or less.

However, thicker layers may be used as appropriate.

[0047] It will be appreciated that in different exemplary implementations, different specific processes may be used for the formation of the conductive and dielectric layers based on the fab or assembly suppliers' capabilities and/or based on the desired feature size and cost targets. Features sizes typically range from a few microns to the deep sub-micron range, depending on the process.

[0048] Conductor patterns formed within the conductive and dielectric layers during stage 402 may include capacitive sensor arrays and interconnects. Various patterns for the capacitive sensor arrays are possible, one example being a transcapacitive conductor pattern having a set of transmitter sensor electrodes (or "traces") extending orthogonally to a set of receiver sensor electrodes (or "traces"), with the receiver and transmitter traces separated from each other by dielectric material and forming a two-dimensional array of sensing pixels at the locations where they crossover. Multiple sets of conductor patterns (for multiple individual fingerprint sensor packages) may be simultaneously formed on the large glass substrate via a set of processing steps in accordance with stage 402. In certain exemplary embodiments, the receiver sensor electrodes are disposed closer to the sensing surface, with the transmitter sensor electrodes being disposed below the receiver sensor electrodes. Thus, the transmitter sensor electrodes may be patterned first as part of a first conductive layer, followed by depositing a dielectric layer thereon, with the receiver sensor electrodes being patterned on top of the dielectric layer as part of a second conductive layer.

[0049] Compared to the high-end laminated or build-up substrate technology used for current capacitive fingerprint sensor devices, these fab technologies are at least three times smaller than (and often many more times smaller than) existing build-up or laminate organic substrate processing capabilities. Additionally, the feature size control and corresponding tolerance is much better than those used in laminate or build-up substrate fabrication.

[0050] After the conductive and dielectric layers have been formed so as to pattern multiple capacitive sensor arrays on the large glass substrate, at stage 403, the large glass panel may be separated into multiple sub-panels for ease of handling in downstream processing steps. The process for separation may include a scribe and break process, diamond saw dicing, laser cutting, a water jet process, or plasma or wet etching. Depending on the shape and thickness of the glass, as well as the desired edge quality, different processes may be selected. For example, square or rectangular finished shapes lend themselves to a scribe and break process or diamond saw dicing. Rounded or more complex shapes are more compatible with laser, water jet or etch processing. In typical situations, a scribe and break process is sufficient for separation of the glass panel into glass sub-panels in stage 403.

[0051] At stage 404, fingerprint sensor chips (or "ICs" or "dies") are attached to respective conductors (e.g., interconnects) of the respective conductive and dielectric layers of the multiple sub-panels. This attachment may be performed via standard chip attach process such as flip chip (via soldering), chip-on-glass (COG) (via conductive bumps contacting one another via an anisotropic conducting film (ACF)), or chip attach via wire bonding. Other processes may also be used based on manufacturer capabilities and cost structure demands. It will be appreciated that the fingerprint sensor chips may be silicon chips (or "silicon ICs" or "silicon dies"). In certain exemplary implementations, fine pitch COG attach processes, which are typically done with anisotropic conducting films (ACFs), are used to allow for reductions in die size to further minimize cost. For example, by using ACFs, a COG pad pitch of 14um or less with bump sizes of 14um or lower can be achieved.

[0052] After the process depicted in FIG. 4 has been completed, it may be desirable to protect the fingerprint sensor chip and/or the top surface of the conductive and dielectric layers, so as to protect the components of the fingerprint sensor package. Further, it may be desirable to form the fingerprint sensor package in a configuration that is more easily incorporated into an end device. FIG. 5 is a schematic flowchart depicting further exemplary processing steps for manufacturing fingerprint sensor packages on a glass substrate, including formation of a protective layer.

[0053] Stage 501 depicts a glass sub-panel, to which a plurality of fingerprint sensor chips is attached, resulting from the process depicted in FIG. 4. It will be appreciated that the size of the sub-panel depends on the starting glass panel size and the standardized manufacturing process for that starting glass panel size (for example, a generation 4 LCD panel may be quartered at stage 403). It will further be appreciated that the number of chips disposed on each glass sub-panel is based on the desired fingerprint sensor package size and the glass sub-panel size.

[0054] At stage 502, a protective layer may be applied to the top surface. This processing step may be performed in a very cost-effective manner via existing equipment typically found in many outsourced assembly and test (OSAT) factories. The protective layer may be applied in a variety of ways, including but not limited to: a laminated film, a spray-on or deposited coating, a molded material, etc. By selecting an appropriate protective layer material and deposition technique, the thickness and coating properties of the protective layer may be controlled so as to assure reliable operation of the fingerprint sensor. In various exemplary implementations, the protective layer materials may be, but are not limited to, a molding material, heat or UV-cured epoxies or acrylics, laminated films such as polyethylene terephthalate, or spray on or similarly deposited polymer materials. For example, a protective layer may be applied via injection or compression molding of a polymer-based molding compound onto the surface of the sensor.

[0055] At stage 503, the glass sub-panel is singulated such that each individual fingerprint sensor package is separated from the other individual fingerprint sensor packages. The singulation may be accomplished in a variety of ways, including those discussed above with respect to stage 403 of FIG. 4. In certain exemplary implementations, laser, water jet or etch singulation may be advantageous for stage 503 to achieve a particular desired fingerprint sensor package shape.

[0056] In certain exemplary embodiments, the individual fingerprint sensor packages are distributed on the glass sub-panel such that there is sufficient distance between them to allow for flexible singulation to accommodate different fingerprint sensor package shapes (e.g., rectangular, square, rounded, circular, etc.).

[0057] Stage 504 depicts an individual fingerprint sensor package after the singulation of stage 503. [0058] After completion of the process depicted in FIG. 5, fingerprint sensor packages may then be tested to verify performance and are ready for integration into end devices. Integration into an end device may be accomplished by connecting a fingerprint sensor package to the electronics of the end device through a flexible printed circuit board (PCB) (or "flex"). An exemplary attach region for a flex is shown as element 510 of FIG. 5.

[0059] It will be appreciated that the steps discussed above with respect to FIGS. 4-5 may be performed in a different order in different exemplary embodiments. For example, in certain other exemplary embodiments, chip attachment and/or application of the protective layer may be performed after singulation.

[0060] FIGS. 6A-6C are schematic block diagrams depicting cross-sections of exemplary fingerprint sensor packages in accordance with some exemplary embodiments. The fingerprint sensor package includes a glass substrate 610, conductive and dielectric layers 620 deposited onto the glass substrate 610 (e.g., as discussed above with respect to stage 402 of FIG. 4), a fingerprint sensor chip 630 attached to the conductive and dielectric layers 620 (e.g., as discussed above with respect to stage 404 of FIG. 4), and a protective layer 640a, 640b, 640c surrounding the fingerprint sensor chip 630 and disposed over the conductive and dielectric layers 620. Additionally, a flex 650 may be connected to the conductive and dielectric layers 620 (e.g., via a flex-on-glass attachment). The conductive and dielectric layers 620 may include patterned conductors 621 which correspond to transmitter and receiver traces of the fingerprint sensor (forming a capacitive sensor array), as well as other connective elements (e.g., respective conductors for the fingerprint sensor chip 630 and for the conductive interface for receiving the flex 650).

[0061] The total thickness of the fingerprint sensor package may be, for example, 700um or less, with the thickness of the glass substrate 610 being, for example, 500um, the thickness of the conductive and dielectric layers 620 being, for example, 3um or less, and the thickness of the protective layer 640a, 640b, 640c being, for example, 170-200um. The height of the fingerprint sensor chip 630 may be, for example, 150um.

[0062] In the example depicted in FIG. 6A, the protective layer 640a does not cover the conductive interface for the flex 650 such that the flex 650 may be attached and detached even after the protective layer is applied. In the examples depicted in FIGS. 6B and 6C, the flex 650 is attached before the protective layer 640b, 640c is applied, and once the protective layer 640b, 640c is applied, the flex 650 is no longer readily detachable from the fingerprint sensor package. In other words, the flex 650 is "captured" by the protective layer 640b, 640c in the examples depicted in FIGS. 6B and 6C, for example by partially encapsulating the flex. It will be appreciated that the same mold compound or other encapsulant that is used for encapsulating the fingerprint sensor chip 630 and the capacitive sensor array may also be used for encapsulating the flex. In FIG. 6C in particular, the flex is folded over an edge of the glass substrate 610, and the edge of the glass substrate 610 is also sealed with the mold compound or other encapsulant. It will be appreciated that the example depicted in FIG. 6A, wherein the flex 650 is not "captured," may be advantageous for ease of attachment and detachment of a flex.

[0063] FIGS. 6A-6C further depict a biometric object 660 (e.g., a finger) above the protective layer 640a, 640b, 640c. An upper surface of the protective layer 640a, 640b, 640c, above the transmitter and receiver electrodes of the fingerprint sensor, corresponds to a sensing surface for a fingerprint and provides a sensing region for the fingerprint sensor, and features of the biometric object 660 are detected through the protective layer 640a, 640b, 640c. It will be appreciated that the protective layer may be relatively thicker when the fingerprint sensor chip and the sensor array are able to detect features of a fingerprint at a relatively farther distance, and that the protective layer may be relatively thinner when the fingerprint sensor chip and the sensor array have a relatively shorter sensing distance. The protective layer 640a, 640b, 640c may also serve as a decorative layer. For example, the protective layer 640a, 640b, 640c may be a clear, UV-cured poly-coating with an ink layer applied thereto.

[0064] In the examples shown in FIGS. 6A-6C, the fingerprint sensor chip 630 is connected on the same side of the glass substrate 610 as the patterned conductors 621, which avoids the need to connect the sensor pattern of the fingerprint sensor to a fingerprint sensor chip located on an opposite side of the glass substrate 610 (and thus avoids the need for through-glass vias). To achieve this, the thickness of the protective layer 640a, 640b, 640c should be greater than the height of the fingerprint sensor chip 630. In an exemplary embodiment, the protective layer 640a, 640b, 640c may be a poly-coating that has a thickness that is higher than the fingerprint sensor chip 630. In an exemplary embodiment, the height of the fingerprint sensor chip 630 may be, for example, up to 300-350um. In another exemplary embodiment, the fingerprint sensor chip 630 may be aggressively thinned such that its height is less than lOOum, and the protective layer 640 is formed with an encapsulant that is thicker than the height of the fingerprint sensor IC.

[0065] Conventional capacitive fingerprint sensor devices, in contrast to the examples shown in FIGS. 6A-6C, are focused on locating the die elsewhere, e.g., within the sensing area on the opposite side of the substrate or underneath an area of a flexible substrate that is folded over the sensing die. Thus, these conventional designs are limited with respect to the form factor and use of the fingerprint sensor.

[0066] FIGS. 7A-7B are schematic block diagrams depicting cross-sections of exemplary fingerprint sensor packages in accordance with some other exemplary embodiments. The fingerprint sensor package includes a glass substrate 610, conductive and dielectric layers 620 deposited onto the glass substrate 610 (e.g., as discussed above with respect to stage 402 of FIG. 4), a fingerprint sensor chip 730 attached to the conductive and dielectric layers 620 (e.g., as discussed above with respect to stage 404 of FIG. 4), and a protective layer disposed over the capacitive sensor array having an adhesive layer 741 (e.g., comprising an optically clear adhesive (OCA)), a decorative layer 742 (e.g., an ink layer), and a hardened or laminated glass layer 743. Additionally, a flex 650 may be connected to the conductive and dielectric layers 620 (e.g., via a flex-on-glass attachment). The conductive and dielectric layers 620 include patterned conductors 621 which correspond to transmitter and receiver traces of the fingerprint sensor (forming a capacitive sensor array), as well as other connective elements (e.g., respective conductors for the fingerprint sensor chip 630 and for the conductive interface for the flex 650). In these examples, because the fingerprint sensor chip 730 is not covered by the protective layer, the fingerprint sensor chip 730 may be separately protected and covered, e.g., by epoxy.

[0067] The hardened or laminated glass layer 743 may provide a durable glass surface as a fingerprint sensing interface for a user. The decorative layer 742 may be disposed above (as shown in FIG. 7B) or below (as shown in FIG. 7A) the hardened or laminated glass layer 743.

[0068] In a further exemplary embodiment, the hardened or laminated glass layer 743 may further extend over the fingerprint sensor chip 730 if the height of the fingerprint sensor chip 730 is low enough such that the fingerprint sensor chip 730 would fit under the hardened or laminated glass layer 743.

[0069] The total thickness of the fingerprint sensor package may be, for example, 700um or less, with the thickness of the glass substrate 610 being, for example, 500um, the thickness of the conductive and dielectric layers 620 being, for example, 3um or less, the thickness of the adhesive layer 741 being, for example, 30um, the thickness of the decorative layer 742 being, for example, 30um, and the thickness of the hardened or laminated glass layer 743 being, for example, 125um or 140um. The height of the fingerprint sensor chip 630 may be, for example, 150um. [0070] An exemplary process for manufacturing the fingerprint sensor package shown in FIG. 7 may include, for example, forming conductive and dielectric layers on a glass panel, separating the glass panel into sub-panels, applying a protective film to each sub-panel, singulating the sub-panels, performing flex attach and chip attach for each of the individual packages, and applying a hardened or laminated glass layer with an ink layer for each of the individual packages.

[0071] FIG. 8 is a schematic block diagram depicting a cross-section of an exemplary fingerprint sensor package in accordance with another exemplary embodiment. The example of FIG. 8 is "upside-down" relative to the example depicted in FIG. 6A in that the biometric object 660 is sensed through the glass substrate 810 (thus the glass substrate 810 is at the "top" of the fingerprint sensor package— corresponding to the sensing surface or "input surface"— and the protective layer 840 is at the "bottom" of the fingerprint sensor package). The fingerprint sensor package includes the glass substrate 810, conductive and dielectric layers 620 deposited onto the glass substrate 610 (e.g., as discussed above with respect to stage 402 of FIG. 4), a fingerprint sensor chip 630 attached to the conductive and dielectric layers 620 (e.g., as discussed above with respect to stage 404 of FIG. 4), and the protective layer 840 which surrounds the fingerprint sensor chip 630 and is disposed under the conductive and dielectric layers 620. The thickness of the protective layer 840 may be, for example, 170-200um. Additionally, a flex 650 may be connected to the conductive and dielectric layers 620 (e.g., via a flex-on-glass attachment). The conductive and dielectric layers 620 include patterned conductors 621 which correspond to transmitter and receiver traces of the fingerprint sensor (forming a capacitive sensor array), as well as other connective elements (e.g., respective conductors for the fingerprint sensor chip 630 and for the conductive interface for the flex 650).

[0072] In the example depicted in FIG. 8, the glass substrate 810 may be thinned, and a surface of the glass substrate 810 opposite the conductive and dielectric layers 620 corresponds to a sensing surface for a fingerprint. For example, the glass substrate 810 may have a starting thickness of up to 500um, and may be thinned down to 350um or less (e.g., 150um or 200um). The thinning of the glass substrate 810 may be performed, for example, on glass sub-panels during the manufacturing process before applying the protective layer and singulation of the individual sensors. The thinning process may be implemented using standard wafer thinning equipment in an OS AT factory (e.g., mechanically thinning through a polishing process) or in accordance with a standard display fab process (e.g., via etching). For example, a standard display fab process may include two glass sub-panels being adhered face-to-face, with a wet etching process performed on the inactive side of the sub-panels. It will be appreciated that the thickness of the glass substrate 810 may depend on the capabilities of the fingerprint sensor chip and corresponding sensor array (e.g., a fingerprint sensor package having a fingerprint sensor chip and sensor array that is able to detect features of a fingerprint at a relatively farther distance may have a thicker glass substrate than a fingerprint sensor package having a fingerprint sensor chip and sensor array with a relatively shorter sensing distance).

[0073] An exemplary process for manufacturing the fingerprint sensor package shown in FIG. 8 may include, for example, forming conductive and dielectric layers on a glass panel (with a first conductive layer comprising receiver traces being patterned first, followed by a dielectric layer being deposited thereon, and a second conductive layer comprising transmitter traces being patterned onto the dielectric layer), thinning the glass panel, separating the glass panel into sub-panels, applying a protective film to each sub-panel, applying a decorative layer to each sub-panel, singulating the sub-panels, and performing flex attach and chip attach for each of the individual packages.

[0074] FIG. 9 is a schematic block diagram depicting a top view of an exemplary fingerprint sensor package in accordance with an exemplary embodiment. The fingerprint sensor package 900 includes a fingerprint sensor chip 930, with a plurality of conductive traces connected thereto (including a plurality of receiver traces 940 and a plurality of transmitter traces 950 forming a sensing region 960). The fingerprint sensor package further includes an interface 910 (e.g., an ACF bank) to which a flex may be attached.

[0075] In the example depicted in FIG. 9, it can be seen that the fingerprint sensor chip is implemented as a skinny die (i.e., a die having a small Y-dimension and a relatively large X- dimension), which allows relatively more area to be used for the receiver and transmitter traces for a given fingerprint sensor package size. This is advantageous, for example, in applications where the fingerprint package sensor size is constrained (e.g., when the fingerprint sensor package is to be incorporated into a button of an electronic device), and facilitates the fingerprint sensor chip being situated on the same side of the glass substrate as the fingerprint sensor traces. By way of example, the fingerprint sensor chip may have dimensions of approximately 6 x 1 mm, or an aspect ratio (defined by the ratio of width to length of the chip) of greater than 4: 1.

[0076] Further, it is advantageous to minimize the length of routing for receiver traces. Thus, as can be seen in the example depicted in FIG. 9, the routing for the receiver traces 940 extends from the long side of the fingerprint sensor chip 930 such that the receiver traces 940 have a shorter routing path from the sensing region 960 to the fingerprint sensor chip 930 than the transmitter traces 950. In an exemplary embodiment, the receiver traces 940 may be connected to connection pins disposed along a side of the fingerprint sensor chip

corresponding to the X-dimension of the fingerprint sensor chip, which is relatively longer than the side of the fingerprint sensor chip corresponding to the Y-dimension of the fingerprint sensor chip.

[0077] In a further exemplary embodiment, given the relatively high precision of LCM manufacturing processes, the fingerprint sensor chip may have staggered connection pins with a relatively tight pitch such that a relatively larger number of connection pins may be routed to corresponding sensor traces for a given fingerprint sensor chip size.

[0078] Additionally, as shown in FIG. 9, because fabrication on a glass substrate is so cost-effective, an empty space may be provided at the bottom portion of the glass substrate of the fingerprint sensor package such that the receiver and transmitter traces are centered within the fingerprint sensor package. This may be suitable for certain integration applications, such as when the fingerprint sensor package is incorporated into a button of an electronic device.

[0079] It will be appreciated that the example depicted in FIG. 9 depicts a simplified routing pattern for the traces, and that the pattern of the receiver and transmitter traces depicted in FIG. 9, as well as the placement of the components depicted in FIG. 9, are merely exemplary. Other exemplary implementations may have other routing patterns and may utilize other arrangements of the components. In certain preferred implementations, the length of the routing from the fingerprint sensor chip to the receiver and transmitter traces is minimized, particularly with respect to the receiver traces.

[0080] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0081] The use of the terms "a" and "an" and "the" and "at least one" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term "at least one" followed by a list of one or more items (for example, "at least one of A and B") is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0082] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

CLAIMS:

1. A method for manufacturing fingerprint sensor packages having glass substrates, the method comprising:

providing a glass panel;

forming conductive and dielectric layers onto the glass panel, wherein forming the conductive and dielectric layers includes patterning a plurality of capacitive sensor arrays for the fingerprint sensor packages;

attaching a plurality of fingerprint sensor chips to respective conductors of the conductive and dielectric layers on the same side of the glass panel as the plurality of conductive and dielectric layers;

forming a protective layer over the capacitive sensor arrays; and

performing singulation to form individual fingerprint sensor packages.

2. The method according to claim 1 , further comprising:

separating the glass panel into a plurality of sub-panels; and

wherein performing the singulation comprises forming individual fingerprint sensor packages from each of the plurality of sub-panels.

3. The method according to claim 2, wherein separating the glass panel into a plurality of sub-panels is performed before attachment of the plurality of fingerprint sensor chips.

4. The method according to claim 1, wherein attachment of the plurality of fingerprint sensor chips is performed before performing the singulation.

5. The method according to claim 1, wherein attachment of the plurality of fingerprint sensor chips is performed after performing the singulation.

6. The method according to claim 1, wherein forming the conductive and dielectric layers onto the glass panel further comprises forming a conductive interface for receiving a flex for each individual fingerprint sensor package.

7. The method according to claim 6, wherein the protective layer is formed in a manner that does not cover the conductive interface for receiving a flex.

8. The method according to claim 6, further comprising:

attaching a flex to an individual sensor package before forming the protective layer; and

wherein the protective layer is formed over the flex.

9. The method according to claim 1, wherein the attachment of the plurality of fingerprint sensor chips is a chip-on-glass (COG) process.

10. The method according to claim 1, wherein forming the conductive and dielectric layers onto the glass panel further comprises:

patterning a first conductive layer;

depositing a dielectric layer on the first conductive layer; and

patterning a second conductive layer on the dielectric layer.

11. The method according to claim 10, wherein the first conductive layer comprises transmitter sensor electrodes of the plurality of capacitive sensor arrays and the second conductive layer comprises receiver sensor electrodes of the plurality of capacitive sensor arrays.

12. The method according to claim 1 , further comprising:

thinning the glass panel after forming the conductive and dielectric layers onto the glass panel.

13. The method according to claim 12, wherein thinning the glass panel further comprises adhering two glass panels together and performing etching on an inactive side of each glass panel.

14. The method according to claim 12, wherein forming the conductive and dielectric layers onto the glass panel further comprises:

patterning a first conductive layer;

depositing a dielectric layer on the first conductive layer; and patterning a second conductive layer on the dielectric layer;

wherein the first conductive layer comprises receiver sensor electrodes of the plurality of capacitive sensor arrays and the second conductive layer comprises transmitter sensor electrodes of the plurality of capacitive sensor arrays.

15. The method according to claim 1, wherein forming the protective layer further comprises:

forming a hardened or laminated glass layer.

16. The method according to claim 15, wherein the protective layer for an individual fingerprint sensor package is formed over the capacitive sensor array and the fingerprint sensor chip of the fingerprint sensor package.

17. The method according to claim 15, wherein the protective layer for an individual fingerprint sensor package is formed over the capacitive sensor array but not the fingerprint sensor chip of the fingerprint sensor package.

18. The method according to claim 1, wherein the protective layer comprises a molding material.

19. A fingerprint sensor package, comprising:

a glass substrate;

conductive and dielectric layers disposed on the glass substrate, wherein the conductive and dielectric layers comprise a capacitive sensor array;

a fingerprint sensor chip attached to respective conductors of the conductive and dielectric layers, wherein the fingerprint sensor chip is disposed on the same side of the glass substrate as the conductive and dielectric layers; and

a protective layer, disposed over the capacitive sensor array.

20. The fingerprint sensor package according to claim 19, wherein the X- dimension of the fingerprint sensor chip is relatively longer than the Y-dimension of the fingerprint sensor chip, and wherein receiver sensor electrodes of the capacitive sensor array are connected to connection pins disposed along a side of the fingerprint sensor chip corresponding to the X-dimension.

21. The fingerprint sensor package according to claim 19, wherein an upper surface of the protective layer corresponds to a sensing surface for a fingerprint.

22. The fingerprint sensor package according to claim 19, wherein a surface of the glass substrate opposite the capacitive sensor array corresponds to a sensing surface for a fingerprint.

23. The fingerprint sensor package according to claim 19, wherein the fingerprint sensor chip comprises driver circuitry for driving transmitter sensor electrodes of the capacitive sensor array.

24. An electronic device, comprising:

a display;

a processor, configured to cause the display to prompt a user for biometric authentication; and

a fingerprint sensor package, the fingerprint sensor package comprising:

a glass substrate;

conductive and dielectric layers disposed on the glass substrate, wherein the conductive and dielectric layers comprise a capacitive sensor array; a fingerprint sensor chip attached to respective conductors of the conductive and dielectric layers, wherein the fingerprint sensor chip is disposed on the same side of the glass substrate as the conductive and dielectric layers;

a protective layer, disposed over the capacitive sensor array; and a flex, attached to respective conductors of the conductive and dielectric layers, configured to facilitate communication between the fingerprint sensor chip and the processor.