WO2020244006A1 - 指纹芯片、制作指纹芯片的方法和电子设备 - Google Patents

指纹芯片、制作指纹芯片的方法和电子设备 Download PDF

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Publication number
WO2020244006A1
WO2020244006A1 PCT/CN2019/093395 CN2019093395W WO2020244006A1 WO 2020244006 A1 WO2020244006 A1 WO 2020244006A1 CN 2019093395 W CN2019093395 W CN 2019093395W WO 2020244006 A1 WO2020244006 A1 WO 2020244006A1
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WIPO (PCT)
Prior art keywords
layer
fingerprint chip
fingerprint
microlens
wafer
Prior art date
Application number
PCT/CN2019/093395
Other languages
English (en)
French (fr)
Inventor
刘辰锦
张建湘
吴宝全
Original Assignee
深圳市汇顶科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/CN2019/090171 external-priority patent/WO2020243926A1/zh
Application filed by 深圳市汇顶科技股份有限公司 filed Critical 深圳市汇顶科技股份有限公司
Priority to CN201980002569.2A priority Critical patent/CN110720107A/zh
Priority to CN201921006036.5U priority patent/CN210295117U/zh
Priority to PCT/CN2019/093395 priority patent/WO2020244006A1/zh
Priority to CN201921488281.4U priority patent/CN210605734U/zh
Publication of WO2020244006A1 publication Critical patent/WO2020244006A1/zh

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/13—Sensors therefor
    • G06V40/1324—Sensors therefor by using geometrical optics, e.g. using prisms
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/60—OLEDs integrated with inorganic light-sensitive elements, e.g. with inorganic solar cells or inorganic photodiodes
    • H10K59/65—OLEDs integrated with inorganic image sensors

Definitions

  • the embodiments of the present application relate to the field of fingerprint identification, and more specifically, to a fingerprint chip, a method for manufacturing a fingerprint chip, and an electronic device.
  • the optical fingerprint chip As an important part of the electronic device with optical fingerprint recognition function, the optical fingerprint chip is affected by its packaging method, and its thickness is greatly restricted, making it difficult to reduce its volume. Therefore, how to reduce the thickness of the optical fingerprint chip and bring more room for the design of the whole machine structure to electronic equipment manufacturers has become an urgent problem to be solved.
  • the embodiments of the present application provide a fingerprint chip, a method for manufacturing a fingerprint chip, and an electronic device, which can realize an ultra-thin fingerprint chip.
  • a fingerprint chip including: a substrate having a thickness greater than or equal to 30 micrometers and less than 80 micrometers, and a pixel array is formed on the substrate, and the pixel array is used for detecting incident on a finger and The optical signal reflected or scattered by the finger; an optical path layer is arranged above the substrate and is used to transmit the optical signal to the pixel array.
  • the substrate further includes a conductive via structure, and the conductive via structure is used to electrically connect the pixel array and the circuit board of the fingerprint chip.
  • the conductive via structure is formed by a TSV process.
  • the conductive via structure includes a via filled with a metal material, and the metal material is electrically isolated from the material of the substrate by an insulating sidewall.
  • the through hole is a vertical through hole or an inclined through hole.
  • the cross-section of the through hole is rectangular, circular or trapezoidal.
  • the conductive via structure is electrically connected to the circuit board through an electrical connection layer provided on the lower surface of the substrate.
  • the electrical connection layer is a metal layer or an ACF layer.
  • the optical path layer includes a micro lens array.
  • the surface of the microlens array is coated with a protective film layer.
  • the protective film layer is an insulating inorganic material layer.
  • the inorganic material is silicon oxide or silicon nitride.
  • the thickness of the protective film layer is between 0.05 ⁇ m and 1 ⁇ m.
  • the light path layer further includes at least one light blocking layer, the at least one light blocking layer is disposed between the microlens array and the pixel array, wherein each light blocking layer is A plurality of openings corresponding to the plurality of microlenses are provided, and the light signal condensed by each microlens passes through the openings corresponding to the microlenses in different light blocking layers to reach the pixel array.
  • the apertures corresponding to the same microlens in different light blocking layers are sequentially reduced from top to bottom.
  • each microlens corresponds to a pixel, wherein the optical signal condensed by the microlens passes through the openings in different light blocking layers corresponding to the microlens to reach Pixels corresponding to the microlens.
  • the connecting lines of the openings corresponding to the same microlens in different light blocking layers pass through the central area of the optical sensing unit corresponding to the microlens.
  • the projection of the condensing surface of the microlens on a plane perpendicular to its optical axis is a rectangle or a circle.
  • the optical path layer includes a filter layer, and the filter layer is used to filter optical signals of non-specific wavelength bands.
  • the optical signal is a vertical optical signal or an oblique optical signal reflected by the finger.
  • a method for manufacturing a fingerprint chip including:
  • a reinforcement layer is fabricated on a wafer, wherein a plurality of pixel arrays are formed on the wafer, and an optical path layer is arranged above the plurality of pixel arrays, and the optical path layer is used to reflect incident on the finger and reflected by the finger
  • the optical signal of is transmitted to the plurality of pixel arrays, and the reinforcement layer is bonded to the upper surface of the optical path layer through an adhesive layer;
  • each fingerprint chip includes a pixel array
  • the thickness of the wafer after the thinning process is between 30 micrometers and 100 micrometers.
  • the method before the removing the reinforcement layer on each fingerprint chip, the method further includes: electrically connecting the pixel array in each fingerprint chip to the circuit board of the fingerprint chip .
  • the method before the cutting the wafer with the reinforcement layer, the method further includes: performing TSV processing on the thinned wafer through a silicon wafer channel , A plurality of conductive via structures are obtained, wherein the conductive via structures are used to electrically connect the pixel array and the circuit board.
  • the conductive via structure is electrically connected to the circuit board through an electrical connection layer provided on the lower surface of the wafer.
  • the electrical connection layer is a metal layer or an ACF layer.
  • the conductive via structure includes a via filled with a metal material, and the metal material is electrically isolated from the material of the wafer by an insulating sidewall.
  • the through hole is a vertical through hole or an inclined through hole.
  • the cross-section of the through hole is rectangular, circular or trapezoidal.
  • the optical path layer includes a plurality of microlens arrays, and the reinforcement layer is bonded to the plurality of microlens arrays through the adhesive layer.
  • the method before the fabricating the reinforcement layer on the wafer, the method further includes: fabricating a protective film layer on the surface of each microlens array, wherein the adhesive layer covers the Multiple micro lens arrays on the protective film layer.
  • the protective film layer is an insulating inorganic material layer.
  • the inorganic material is silicon oxide or silicon nitride.
  • the thickness of the protective film layer is between 0.05 ⁇ m and 1 ⁇ m.
  • the projection of the condensing surface of each microlens in the microlens array on a plane perpendicular to its optical axis is a rectangle or a circle.
  • the light path layer further includes at least one light blocking layer, the at least one light blocking layer is disposed between the microlens array and the pixel array, wherein each light blocking layer is A plurality of openings corresponding to the plurality of microlenses are provided, and the light signal condensed by each microlens passes through the openings corresponding to the microlenses in different light blocking layers to reach the pixel array.
  • the apertures corresponding to the same microlens in different light blocking layers are sequentially reduced from top to bottom.
  • each microlens corresponds to a pixel, wherein the optical signal condensed by the microlens passes through the openings in different light blocking layers corresponding to the microlens to reach Pixels corresponding to the microlens.
  • the removing the reinforcement layer on each fingerprint chip includes: using a specific solvent to dissolve the adhesive layer between the reinforcement layer and the optical path layer, so that each fingerprint The chip is separated from its reinforcement layer.
  • the removing the reinforcement layer on each fingerprint chip includes: decomposing the adhesive layer between the reinforcement layer and the optical path layer by a laser, so that each fingerprint chip Separate from the reinforcement layer; use a specific solvent to dissolve the residual colloid that has not been decomposed by the laser.
  • the adhesive layer is a temporary bonding adhesive layer.
  • the thickness of the temporary bonding adhesive layer is between 15 ⁇ m and 50 ⁇ m.
  • the reinforcement layer is a glass layer.
  • the thickness of the reinforcement layer is between 200 microns and 1000 microns.
  • an electronic device including the fingerprint chip in the first aspect or any possible implementation of the first aspect.
  • the fixed layer is used to provide mechanical support to the wafer, and the fixed layer is removed after the fingerprint chip is manufactured, which can avoid the wafer from being too thin in the subsequent process.
  • the thickness of the substrate of the fingerprint chip obtained based on this method can reach between 30 microns and 100 microns.
  • Figure 1(a) is a schematic diagram of the structure of an electronic device to which this application can be applied.
  • Fig. 1(b) is a schematic cross-sectional view of the electronic device shown in Fig. 1(a) along the A-A' direction.
  • FIG. 2 is a schematic flowchart of a method for manufacturing a fingerprint chip according to an embodiment of the present application.
  • 3(a) to 3(h) are a possible process flow diagram of the method for manufacturing a fingerprint chip shown in FIG. 2.
  • Fig. 4 is a schematic block diagram of a fingerprint chip according to an embodiment of the present application.
  • FIG. 5 is a schematic diagram of a possible structure of the fingerprint chip shown in FIG. 4.
  • the embodiments of this application can be applied to fingerprint systems, including but not limited to optical, ultrasonic or other fingerprint identification systems and medical diagnostic products based on optical, ultrasonic or other fingerprint imaging.
  • the embodiments of this application only take optical fingerprint systems as an example
  • the embodiments of the present application should not constitute any limitation, and the embodiments of the present application are also applicable to other systems that use optical, ultrasonic, or other imaging technologies.
  • the optical fingerprint system provided in the embodiments of this application can be applied to smart phones, tablet computers, and other mobile terminals with display screens or other electronic devices; more specifically, in the above electronic devices, the fingerprint model The group may specifically be an optical fingerprint module, which may be arranged in a partial area or an entire area below the display screen, thereby forming an under-display or under-screen optical fingerprint system.
  • the optical fingerprint module can also be partially or fully integrated into the display screen of the electronic device, thereby forming an in-display or in-screen optical fingerprint system.
  • the fingerprint recognition technology under the optical screen uses the light returned from the top surface of the device display assembly to perform fingerprint sensing and other sensing operations.
  • the returned light carries the information of the object (for example, a finger) in contact with the top surface.
  • a specific optical sensor module located under the display screen is realized.
  • the design of the optical sensor module can be such that the desired optical imaging can be achieved by appropriately configuring optical elements for collecting and detecting the returned light.
  • FIG. 1(a) and 1(b) show schematic diagrams of electronic devices to which the embodiments of the present application can be applied.
  • 1(a) is a schematic view of the orientation of the electronic device 10
  • FIG. 1(b) is a schematic partial cross-sectional view of the electronic device 10 shown in FIG. 1(a) along the A-A' direction.
  • the electronic device 10 includes a display screen 120 and an optical fingerprint module 130.
  • the optical fingerprint module 130 is arranged in a partial area below the display screen 120.
  • the optical fingerprint module 130 includes an optical fingerprint sensor, and the optical fingerprint sensor includes a sensing array 133 having a plurality of optical sensing units 131.
  • the area where the sensing array 133 is located or the sensing area thereof is the fingerprint detection area 103 of the optical fingerprint module 130 (also referred to as fingerprint collection area, fingerprint recognition area, etc.).
  • the fingerprint detection area 103 is located in the display area of the display screen 120.
  • the optical fingerprint module 130 may also be arranged in other positions, such as the side of the display screen 120 or the non-transparent area of the edge of the electronic device 10, and the optical fingerprint module 130 The optical signal of at least a part of the display area of the display screen 120 is guided to the optical fingerprint module 130, so that the fingerprint detection area 103 is actually located in the display area of the display screen 120.
  • the area of the fingerprint detection area 103 may be different from the area of the sensing array 133 of the optical fingerprint module 130, for example, through an optical path design such as lens imaging, a reflective folding optical path design, or other optical paths such as light convergence or reflection.
  • the design can make the area of the fingerprint detection area 103 of the optical fingerprint module 130 larger than the area of the sensing array 133 of the optical fingerprint module 130.
  • the fingerprint detection area 103 of the optical fingerprint module 130 can also be designed to be substantially the same as the area of the sensing array of the optical fingerprint module 130.
  • the electronic device 10 adopting the above structure does not need to reserve space on the front side for setting fingerprint buttons (such as the Home button), so that a full screen solution can be adopted, that is, the display area of the display screen 120 It can be basically extended to the front of the entire electronic device 10.
  • the optical fingerprint module 130 includes a light detecting part 134 and an optical component 132.
  • the light detection part 134 includes the sensor array 133, a reading circuit electrically connected to the sensor array 133, and other auxiliary circuits, which can be fabricated on a chip (Die) by a semiconductor process, such as an optical imaging chip Or an optical fingerprint sensor.
  • the sensing array 133 is specifically a photodetector (Photodetector) array, which includes a plurality of photodetectors distributed in an array, and the photodetectors can be used as the aforementioned optical sensing unit.
  • the optical component 132 may be disposed above the sensing array 133 of the light detecting part 134, and it may specifically include a filter layer (Filter), a light guide layer or a light path guiding structure, and other optical elements.
  • the filter layer It can be used to filter out ambient light penetrating the finger, and the light guide layer or light path guiding structure is mainly used to guide the reflected light reflected from the surface of the finger to the sensor array 133 for optical detection.
  • the optical component 132 and the light detecting part 134 may be packaged and operated in the same optical fingerprint component.
  • the optical component 132 and the optical detection part 134 can be packaged and operated on the same optical fingerprint chip, or the optical component 132 can be arranged outside the fingerprint chip where the optical detection part 134 is located.
  • the optical component 132 is attached above the fingerprint chip, or some components of the optical component 132 are integrated into the fingerprint chip.
  • the light guide layer or light path guiding structure of the optical component 132 has multiple implementation schemes.
  • the light guide layer may specifically be a collimator layer made on a semiconductor silicon wafer, which has multiple A collimating unit or a micro-hole array.
  • the collimating unit can be specifically a small hole.
  • the reflected light reflected from the finger the light that is perpendicularly incident on the collimating unit can pass through and be passed by the optical sensing unit below it.
  • the light with an excessively large incident angle is attenuated by multiple reflections inside the collimating unit. Therefore, each optical sensing unit can basically only receive the reflected light reflected by the fingerprint pattern directly above it.
  • the sensing array 133 can detect the fingerprint image of the finger.
  • the light guide layer or the light path guide structure may also be an optical lens (Lens) layer, which has one or more lens units, such as a lens group composed of one or more aspheric lenses, which The sensing array 133 of the light detecting part 134 is used to converge the reflected light reflected from the finger to the sensing array 133 of the light detection part 134 below, so that the sensing array 133 can perform imaging based on the reflected light, thereby obtaining a fingerprint image of the finger.
  • the optical lens layer may further have a pinhole formed in the optical path of the lens unit, and the pinhole may cooperate with the optical lens layer to expand the field of view of the optical fingerprint module 130 to improve The fingerprint imaging effect of the optical fingerprint module 130 is described.
  • the light guide layer or the light path guide structure may also specifically adopt a micro-lens (Micro-Lens) layer.
  • the micro-lens layer has a micro-lens array formed by a plurality of micro-lenses, which can be grown by semiconductors.
  • a process or other processes are formed above the sensing array 133 of the light detecting part 134, and each microlens may correspond to one of the sensing units of the sensing array 133, respectively.
  • other optical film layers may be formed between the microlens layer and the sensing unit, such as a dielectric layer or a passivation layer.
  • a light-blocking layer (or called a light-blocking layer, a light-blocking layer, etc.) with micro-holes may also be included between the micro-lens layer and the sensing unit, wherein the micro-holes are formed in their corresponding micro-holes.
  • the light blocking layer can block the optical interference between the adjacent microlens and the sensing unit, and make the light corresponding to the sensing unit converge into the inside of the microhole through the microlens. It is transmitted to the sensing unit via the micro-hole for optical fingerprint imaging.
  • a micro lens layer may be further provided above or below the collimator layer or the optical lens layer.
  • the collimator layer or the optical lens layer is used in combination with the micro lens layer, its specific laminated structure or optical path may need to be adjusted according to actual needs.
  • the display screen 120 may adopt a display screen with a self-luminous display unit, such as an organic light-emitting diode (Organic Light-Emitting Diode, OLED) display or a micro-LED (Micro-LED) display.
  • a self-luminous display unit such as an organic light-emitting diode (Organic Light-Emitting Diode, OLED) display or a micro-LED (Micro-LED) display.
  • OLED Organic Light-Emitting Diode
  • Micro-LED Micro-LED
  • the optical fingerprint module 130 can use the display unit (ie, an OLED light source) of the OLED display screen 120 in the fingerprint detection area 103 as an excitation light source for optical fingerprint detection.
  • the display screen 120 emits a beam of light 111 to the target finger 140 above the fingerprint detection area 103.
  • the light 111 is reflected on the surface of the finger 140 to form reflected light or pass through all the fingers.
  • the finger 140 scatters to form scattered light.
  • the above-mentioned reflected light and scattered light are collectively referred to as reflected light. Because the ridge 141 and valley 142 of the fingerprint have different light reflection capabilities, the reflected light 151 from the fingerprint ridge and the reflected light 152 from the fingerprint valley have different light intensities, and the reflected light passes through the optical component 132.
  • the electronic device 10 realizes the optical fingerprint recognition function.
  • the optical fingerprint module 130 may also use a built-in light source or an external light source to provide an optical signal for fingerprint detection.
  • the optical fingerprint module 130 may be suitable for non-self-luminous display screens, such as liquid crystal display screens or other passively-luminous display screens.
  • the optical fingerprint system of the electronic device 10 may also include an excitation light source for optical fingerprint detection.
  • the excitation light source may specifically be an infrared light source or a light source of non-visible light of a specific wavelength, which may be arranged under the backlight module of the liquid crystal display or in the edge area under the protective cover of the electronic device 10, and the The optical fingerprint module 130 may be arranged under the edge area of the liquid crystal panel or the protective cover and guided by the light path so that the fingerprint detection light can reach the optical fingerprint module 130; or, the optical fingerprint module 130 may also be arranged at all Below the backlight module, and the backlight module is designed to allow the fingerprint detection light to pass through the liquid crystal panel and the backlight module and reach the optical Fingerprint module 130.
  • the optical fingerprint module 130 uses a built-in light source or an external light source to provide an optical signal for fingerprint detection, the detection principle is the same as that described above.
  • the electronic device 10 may also include a transparent protective cover, and the cover may be a glass cover or a sapphire cover, which is located above the display screen 120 and covers the electronic device.
  • the front of 10. Therefore, in the embodiments of the present application, the so-called finger pressing on the display screen 120 actually refers to pressing on the cover plate above the display screen 120 or covering the surface of the protective layer of the cover plate.
  • the optical fingerprint module 130 may include only one optical fingerprint sensor.
  • the fingerprint detection area 103 of the optical fingerprint module 130 has a small area and a fixed position, so the user is performing During fingerprint input, it is necessary to press the finger to a specific position of the fingerprint detection area 103, otherwise the optical fingerprint module 130 may not be able to collect the fingerprint image, resulting in poor user experience.
  • the optical fingerprint module 130 may specifically include multiple optical fingerprint sensors. The multiple optical fingerprint sensors may be arranged side by side under the display screen 120 in a splicing manner, and the sensing areas of the multiple optical fingerprint sensors together constitute the fingerprint detection area 103 of the optical fingerprint module 130.
  • the fingerprint detection area 103 of the optical fingerprint module 130 can be extended to the main area of the lower half of the display screen, that is, to the area where the finger is habitually pressed, so as to realize the blind fingerprint input operation. Further, when the number of optical fingerprint sensors is sufficient, the fingerprint detection area 103 can also be extended to half of the display area or even the entire display area, thereby realizing half-screen or full-screen fingerprint detection.
  • fingerprint chip is affected by its packaging method, and its thickness is greatly restricted.
  • the embodiment of the application provides a method for manufacturing a fingerprint chip, which can obtain an ultra-thin fingerprint chip.
  • the aforementioned optical sensing unit 131 is also referred to as a pixel or a photosensitive pixel
  • the sensing array 133 is also referred to as a pixel array
  • the optical component 132 is also referred to as an optical path layer.
  • FIG. 2 is a schematic flowchart of a method for manufacturing a fingerprint chip according to an embodiment of the present application. As shown in Figure 2, part or all of the following steps are included.
  • a reinforcement layer is fabricated on the wafer.
  • a plurality of pixel arrays are formed on the wafer, and an optical path layer is disposed above the plurality of pixel arrays, and the optical path layer is used to transmit optical signals incident on the finger and reflected by the finger to the plurality of pixel arrays.
  • the reinforcement layer is bonded to the upper surface of the optical path layer through the adhesive layer.
  • the material of the wafer may be a semiconductor material such as silicon.
  • a plurality of pixel arrays are formed on the wafer, and an optical path layer is arranged above the plurality of pixel arrays.
  • the reinforcing layer is arranged above the optical path layer, for example, the reinforcing layer may be bonded to the upper surface of the optical path layer through an adhesive layer.
  • the reinforcement layer is always connected to the wafer, so as to provide mechanical support for the wafer, until the independent fingerprint chip is manufactured and then removed.
  • Each pixel array includes a plurality of pixels formed by, for example, a plurality of photoelectric secondary lights.
  • An optical path layer is arranged above these pixel arrays.
  • the optical path layer can transmit the light signal reflected or scattered by the finger above the display screen to the pixel array.
  • the optical signal carries the fingerprint information of the finger. Therefore, fingerprint information can be performed based on the fingerprint information. Recognition.
  • the adhesive layer used to connect the reinforcement layer and the optical path layer can be, for example, a temporary bonding adhesive layer.
  • the adhesive layer can be coated on the optical path layer. After the adhesive layer is cured, the fixed layer and the optical path layer can be formed. The effective bonding.
  • the glue layer can be dissolved in a specific solvent to lose bonding.
  • the thickness of the glue layer may be between 15 ⁇ m and 50 ⁇ m, for example.
  • the optical path layer may include a plurality of micro lens arrays, and the reinforcement layer is bonded to the plurality of micro lens arrays through the glue layer.
  • the method further includes: fabricating a protective film layer on the surface of each microlens array, wherein the glue layer covers the On the protective film layer.
  • the protective film layer plated on the surface of the micro lens array is used to protect each micro lens from being damaged in the subsequent process.
  • the glue layer covers the upper surface of the protective film layer of the plurality of micro lens arrays.
  • the protective film layer may be a chemically stable insulating inorganic material layer grown by a plating method, such as silicon oxide or silicon nitride.
  • the inorganic material covers all the micro lens arrays on the upper surface of the wafer.
  • the thickness of the protective film layer may be, for example, 0.05 ⁇ m to 1 ⁇ m.
  • the optical path layer may also include other optical components, such as a light blocking layer, a filter layer, and the like.
  • optical components such as a light blocking layer, a filter layer, and the like.
  • the reinforcement layer may be, for example, a glass layer or the like, which is used to support the wafer during the process of manufacturing the fingerprint chip.
  • the thickness of the reinforcement layer can be, for example, between 200 microns and 1000 microns.
  • the wafer with the reinforcement layer is thinned.
  • the wafer can be thinned under the support and stability of the reinforcement layer.
  • the thinning process may be, for example, using mechanical polishing, chemical substrate etching, and chemical mechanical polishing (Chemical Mechanical Polishing, CMP) to remove wafer material from the back of the wafer to thin the wafer.
  • CMP Chemical Mechanical Polishing
  • the thickness of the wafer after the thinning process can be, for example, between 30 microns and 250 microns, further between 30 and 100 microns, further between 30 and 80 microns, or greater than or equal to 30 microns and less than 80 microns , And even thinner.
  • the wafer with the reinforcement layer is cut to obtain a plurality of fingerprint chips.
  • each fingerprint chip includes a pixel array, and an optical path layer corresponding to the pixel array is provided above the pixel array. After the fingerprint chips are separated from the wafer, the fixed layer still exists above each fingerprint chip, so the fixed layer needs to be removed.
  • the reinforcement layer When performing various manufacturing processes of the fingerprint chip based on the wafer, the reinforcement layer is always connected to the wafer, so as to mechanically support the wafer to protect the wafer from damage during processing. After each fingerprint chip is formed, the reinforcement layer is removed.
  • each fingerprint chip By removing the glue layer between each fingerprint chip and the fixed layer above it, each fingerprint chip can be separated from the fixed layer above it.
  • a specific solvent is used to dissolve the glue layer between the reinforcement layer and the optical path layer, so that each fingerprint chip is separated from the reinforcement layer.
  • the adhesive layer between the reinforcement layer and the optical path layer is decomposed by laser or ultraviolet light to separate each fingerprint chip from the reinforcement layer; and a specific solvent is used to dissolve the residual colloid that has not been decomposed by the laser.
  • the specific solvent only dissolves the glue layer, and does not cause damage to the protective film layer and circuit board on the surface of the microlens array.
  • the method further includes: electrically connecting the pixel array in each fingerprint chip with the circuit board of the fingerprint chip.
  • the thinned wafer can be processed through Silicon Vias (TSV) to obtain multiple conductive via structures.
  • TSV Silicon Vias
  • the conductive via structure is used to electrically connect the pixel array and the circuit board.
  • the TSV process may include, for example, the formation of through holes, the formation of insulating sidewalls, and the filling of through holes.
  • the TSV process in the related art please refer to the TSV process in the related art, which will not be repeated here.
  • the fingerprint chip adopts a conductive via structure to realize electrical connection between the pixel array of the fingerprint chip and the circuit board. After the multiple wire via structures are obtained, the wafer is cut to obtain multiple fingerprint chips, and then the pixel array is electrically connected to the circuit board through the conductive via structure, thereby completing the fingerprint chip packaging . Therefore, it is possible to avoid arranging package bonding wires connecting the upper surface pads of the fingerprint chip and the lower surface pads of the fingerprint chip outside the fingerprint chip, overcome the influence of the arc height of the package bonding wires on the thickness of the optical fingerprint device, so that the fingerprint chip can achieve Thinner.
  • the conductive through hole structure includes a through hole filled with a metal material, and the metal material is electrically isolated from the material of the wafer by an insulating sidewall.
  • the metal material can be, for example, aluminum, copper, tungsten, polymer conductor, etc., which can be formed by electroplating, metal deposition, or the like.
  • the material of the insulating sidewall may be, for example, oxide, silicon nitride, or the like.
  • the conductive via structure may be electrically connected to the circuit board through an electrical connection layer provided on the lower surface of the wafer, for example. After each fingerprint chip is obtained, the electrical connection layer is connected to the circuit board of the fingerprint chip. That is, one end of the conductive via structure is electrically connected to the pad on the upper surface of the wafer, and the other end is electrically connected to the electrical connection layer on the lower surface of the wafer.
  • the electrical connection layer may be, for example, a pad or an anisotropic conductive film (ACF) layer or the like.
  • the through holes in the conductive through hole structure may be vertical through holes or inclined through holes.
  • the present application does not limit the inclination angle of the through hole, for example, it may be an included angle between 45° and 90° with the lower surface of the fingerprint chip.
  • the present application does not limit the shape of the through hole, for example, the cross section of the through hole may be circular, rectangular, trapezoidal or other polygonal shapes.
  • the fixed layer is used to provide mechanical support to the wafer, and the fixed layer is removed after the fingerprint chip is made, which can avoid the wafer from being too thin in the subsequent process to cause warping And other issues, it is possible to make an ultra-thin fingerprint chip.
  • FIGS. 3(a) to 3(h) the method of manufacturing a fingerprint chip according to an embodiment of the present application will be described in detail.
  • Figures 3(a) to 3(h) show the wafer 301, the microlens array 302, the protective film layer 303 plated on the microlens 302, the glass layer 304, and the glass layer 304 for bonding the wafer 301
  • FIGS. 3(a) to 3(h) only take two microlens arrays as examples. Be explained. In actual operation, a large number of micro lens arrays 302 can be fabricated on one wafer.
  • a protective film layer 303 is plated on the upper surface of the microlens array 302.
  • a temporary bonding adhesive layer 305 is spin-coated on the wafer 301 on which the microlens array 302 is formed. Wherein, the temporary bonding adhesive layer 305 covers the protective film layer 303.
  • the wafer 301 coated with the temporary bonding glue layer 305 and the glass layer 304 are bonded and cured. So far, the glass layer 304 is fixed above the wafer 301 by the temporary bonding glue layer 305.
  • the subsequent process shown in FIGS. 3(d) to 3(g) is called a fingerprint chip packaging process.
  • the glass layer 304 is always in a bonded state with the wafer 301.
  • the wafer 301 having the glass layer 304 is thinned.
  • the material of the wafer can be ground from the direction of the back 3011 of the wafer 301 to a desired thickness. Since the glass layer 304 supports and stabilizes the wafer 301, the problem of warpage caused when the thickness of the wafer 301 is thin is avoided, and a thinner wafer thickness, such as greater than or equal to 30 microns and less than 80, can be achieved. Micrometers.
  • TSV processing is performed on the thinned wafer 301, and a conductive via structure 306 is formed on the wafer 301.
  • the conductive via structure 306 is located in an area outside the area where the microlens array 302 is located, and can electrically connect the upper surface 3012 and the lower surface 3011 of the wafer 301.
  • an electrical connection layer 307 is provided on the lower surface 3011 of the wafer 301.
  • One end of the conductive via structure 306 can be connected to the pad on the upper surface 3012 of the wafer 301, and the other end is connected to the electrical connection layer 307.
  • each fingerprint chip includes a microlens array 302, and the microlens array is used to transmit optical signals to a pixel array below it, which is not shown here.
  • the obtained fingerprint chip is connected to its circuit board 308.
  • the electrical connection layer 307 can be connected to the circuit board 308 to complete the packaging of the fingerprint chip.
  • FIG. 3(g) shows a fingerprint chip after packaging. At this time, a glass layer 304 is connected to the fingerprint chip.
  • the entire fingerprint chip obtained in Figure 3(g) is immersed in a specific solvent that can dissolve the temporary bonding adhesive layer 305, thereby dissolving the temporary bonding adhesive layer 305, so that the glass layer 304 is Fingerprint chip separation; alternatively, laser or ultraviolet light can be used to decompose the temporary bonding adhesive layer 305 according to the temporary bonding material to separate the glass layer 304 from the fingerprint chip, and then use a device that can dissolve the temporary bonding adhesive layer 305
  • the specific solvent removes the temporary bonding material remaining on the surface of the fingerprint chip, and finally the fingerprint chip shown in Figure 3(h) is obtained.
  • optical path layer is provided above the wafer 301, and in 3(a) to 3(h), only the microlens array 302 in the optical path layer is shown.
  • the optical path layer may also include other optical devices such as a light filter layer and a light blocking layer.
  • other structures may be provided between the wafer 301 and the glass layer 304, such as layers with other electrical structures. For brevity, neither is shown here.
  • each pixel array may correspond to a micro lens array, and the pixel array is used to detect the optical signal transmitted by the corresponding micro lens array 302.
  • the pixel array is not shown in FIGS. 3(a) to 3(h).
  • the pixel array includes a plurality of pixels, and each pixel can be used to detect light signals and convert them into electrical signals.
  • the pixel may be a photodiode or the like, for example.
  • the fixed layer is removed after the packaged fingerprint chip is obtained.
  • the sequence of the steps in the packaging process of the fingerprint chip is not limited. For example, TSV processing can be performed first and then wafer thinning can be performed, or TSV processing can be performed after thinning first.
  • the fingerprint chip 400 includes a substrate 410 and an optical path layer 420.
  • the thickness of the substrate 410 is between 30 micrometers and 100 micrometers.
  • a pixel array is formed on the substrate 410, and the pixel array is used to detect light signals incident on the finger and reflected or scattered by the finger.
  • the optical path layer 420 is disposed above the substrate 410 and is used to transmit the optical signal reflected or scattered by the finger to the pixel array.
  • the light source used to illuminate the finger may be, for example, a light-emitting unit in a self-luminous display such as an OLED display screen, or other external excitation light sources, which are not limited here.
  • the optical signal may be a vertical optical signal or an oblique optical signal reflected by the finger.
  • the contrast of the fingerprint valley and ridge can be improved, and it has better fingerprint recognition performance for special fingers such as dry fingers.
  • the fingerprint chip 400 further includes a circuit board 430, which includes, for example, auxiliary circuits and processing circuits of the pixel array.
  • the substrate 410 may be formed of the aforementioned wafer, such as the wafer 301 in FIGS. 3(a) to 3(h), and the substrate 410 may be, for example, a silicon substrate. It can be seen that the thickness of the substrate 410 formed by the method shown in FIG. 2 can reach 30 micrometers to 100 micrometers, for example, it can be generally greater than or equal to 30 micrometers and less than 80 micrometers. Thus, the ultra-thin fingerprint chip is realized, which brings more room for the design of the whole machine structure to mobile phone manufacturers. Wherein, the fingerprint chip 400 may be pasted on the lower surface of the display screen of the mobile phone, or fixed under the display screen through a middle frame.
  • the substrate 410 further includes a conductive via structure for electrically connecting the pixel array and the circuit board 430 of the fingerprint chip.
  • the conductive via structure may be formed by a TSV process, for example.
  • the conductive via structure is a via filled with a metal material, and the metal material is electrically isolated from the material of the base 410 by an insulating sidewall.
  • the through hole may be a vertical through hole or an inclined through hole.
  • the cross section of the through hole can be rectangular, circular or trapezoidal, and can also be any other shape. This application does not limit this.
  • the electrical connection layer may be a metal layer or an ACF layer, for example.
  • the light path layer 420 may include a micro lens array.
  • the projection of the condensing surface of each microlens in the microlens array on a plane perpendicular to its optical axis may be circular or rectangular. Wherein, when the microlens in the microlens array is a rectangular microlens, it has a better light-collecting area ratio than a circular lens, so that the pixel array can collect more fingerprint information and improve fingerprint recognition performance.
  • the surface of the microlens array may be coated with a protective film layer, for example.
  • the protective film layer may be a chemically stable insulating inorganic material layer grown by a plating method, such as silicon oxide or silicon nitride.
  • the inorganic material covers all the upper surface of the micro lens array.
  • the thickness of the protective film layer may be, for example, 0.05 ⁇ m to 1 ⁇ m.
  • the light path layer 420 may further include at least one light blocking layer, the at least one light blocking layer is sequentially disposed between the microlens array and the pixel array, wherein each light blocking layer is provided with a plurality of microlenses. Corresponding to a plurality of openings, the light signal condensed by each microlens passes through the openings corresponding to the microlens in different light-blocking layers to reach the pixel array.
  • each light-blocking layer can effectively prevent light crosstalk and block stray light in addition to realizing light path guidance, so that oblique light reflected by a finger and meeting a certain preset angle can reach the pixel array through the light-blocking layer.
  • the embodiment of the present application does not limit the number of light blocking layers. Too many light-blocking layers will increase the thickness and complexity of the fingerprint identification device, while too few light-blocking layers will bring more interference light and affect the imaging effect. In actual use, a reasonable number of light blocking layers can be set according to requirements.
  • Each microlens in the microlens array corresponds to a pixel in the pixel array, and the optical signal condensed by the microlens passes through the openings corresponding to the microlens in different light blocking layers to reach the corresponding microlens Of pixels.
  • the oblique angle of the connecting line between the openings corresponding to the same microlens in different light blocking layers is the same as the oblique angle of the oblique light signal.
  • the openings in different light-blocking layers corresponding to the same microlens should have a lateral offset, and the lines of these openings in different light-blocking layers should pass through the corresponding In this way, the oblique light signal can reach the pixel.
  • the apertures corresponding to the same microlens in different light-blocking layers can be sequentially reduced from top to bottom.
  • the microlens Since the microlens has a converging effect on the light, the angle of the converged light beam becomes narrower as it travels downward. Therefore, optionally, the apertures corresponding to the same microlens in different light-blocking layers are sequentially reduced from top to bottom, so that the light beam reaching the pixel is a narrow beam, which realizes the narrow angle reception of the light and ensures collimation. At the same time, it can effectively attenuate unnecessary light, and further improve the clarity of the optical fingerprint image collected by the fingerprint chip.
  • the optical path layer 420 may further include a filter layer, which is used to filter light signals of non-specific wavelength bands, so that light that meets the wavelength condition can reach the pixel, and light that does not meet the wavelength condition is filtered out.
  • a filter layer which is used to filter light signals of non-specific wavelength bands, so that light that meets the wavelength condition can reach the pixel, and light that does not meet the wavelength condition is filtered out.
  • the filter layer can be arranged above the microlens array and connected with the microlens array through a transparent glue layer; or the filter layer can also be arranged below the microlens array; or it can be on the microlens array. At least one filter layer is arranged above and/or below.
  • FIG. 5 shows a schematic diagram of a possible structure of the fingerprint chip of FIG. 4.
  • FIG. 5 shows the substrate 510, the optical path layer 520 and the circuit board 530.
  • a pixel array 511 and a conductive via structure 512 are formed on the substrate 510.
  • the pixel array 511 is electrically connected to the pad 5121 through the driving circuit 513.
  • the lower surface of the substrate 510 is provided with an insulating layer 514, a redistribution layer 531, and an electrical connection layer 532 in this order.
  • the two ends of the conductive via structure 512 are respectively connected to the pad 5121 and the pad 5122, the pad 5122 is connected to the redistribution layer 531 and the electrical connection layer 532 on the lower surface of the substrate 510, and the electrical connection layer 532 is connected to the circuit board 530 , So that the pixel array 511 can be electrically connected to the circuit board 530.
  • the light path layer 520 includes a light filter layer 521, a light filter layer 525, a light blocking layer 523, and a micro lens array 526.
  • the filter layer 521 and the light blocking layer 523 are connected by a dielectric layer or glue layer 522
  • the filter layer 525 and the light blocking layer 523 are connected by a dielectric layer or glue layer 524
  • the microlens array 526 is located on the filter layer. 525 above.
  • the filter layer 521 and the filter layer 525 can be used to filter light of different wavelength bands, so that the light that meets the requirements is transmitted to the pixel array 511.
  • the light signal incident on the finger and reflected or scattered by the finger is condensed by the microlens array 526 and transmitted to the pixel array 511 through the small holes in the light blocking layer 523.
  • the pixel array 511 can convert the optical signal into an electrical signal and further use it for fingerprint identification.
  • the periphery of the fingerprint chip in FIG. 5 can be reinforced with glue 515.
  • the fingerprint chip of the embodiment of the present application has a relatively thin thickness, for example, can reach 150 micrometers to 400 micrometers.
  • the thickness of the substrate 510 can reach a range greater than or equal to 30 microns and less than 80 microns.
  • An embodiment of the present application also provides an electronic device, which includes the fingerprint chip in the foregoing various embodiments of the present application.
  • the electronic device further includes a display screen, and the display screen may be a common non-folding display screen, and the display screen may also be a foldable display screen, or called a flexible display screen.
  • the electronic devices in the embodiments of the present application may be portable or mobile computing devices such as terminal devices, mobile phones, tablet computers, notebook computers, desktop computers, game devices, in-vehicle electronic devices, or wearable smart devices, and Electronic databases, automobiles, bank automated teller machines (Automated Teller Machine, ATM) and other electronic equipment.
  • the wearable smart device includes full-featured, large-sized, complete or partial functions that can be achieved without relying on smart phones, such as smart watches or smart glasses, etc., and only focus on a certain type of application function, and need to cooperate with other devices such as smart phones Use, such as various types of smart bracelets, smart jewelry and other equipment for physical sign monitoring.

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Abstract

一种制作指纹芯片的方法，能够实现超薄指纹芯片。该方法包括：在晶圆上制作加固层，其中，所述晶圆上形成有多个像素阵列，所述多个像素阵列上方设置有光路层，所述光路层用于将入射至手指并经所述手指反射的光信号传输至所述多个像素阵列，所述加固层通过胶层接合在所述光路层的上表面；对具有所述加固层的所述晶圆进行减薄处理；对具有所述加固层的所述晶圆进行切割，得到多个指纹芯片，其中每个指纹芯片包括一个像素阵列；去除各个指纹芯片上的所述加固层。

Description

指纹芯片、制作指纹芯片的方法和电子设备
本申请要求于2019年6月5日提交中国专利局、申请号为PCT/CN2019/090171、名称为“光学指纹装置和电子设备”的PCT申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及指纹识别领域，并且更具体地，涉及一种指纹芯片、制作指纹芯片的方法和电子设备。
背景技术
伴随着科学技术的进步以及用户需求的逐步提升，电子设备的集成度越来越高。为了适应这种发展趋势，电子设备当中使用的各类元件、器件也面临着向集成度更高、体积更小、标准化程度更高的方向转变。
光学指纹芯片作为具有光学指纹识别功能的电子设备的重要组成部分，受其封装方式的影响，其厚度受到了很大的限制，从而很难减小其体积。因此，如何减小光学指纹芯片的厚度，给电子设备厂商带来更大的整机结构设计空间，成为一个亟待解决的问题。
发明内容
本申请实施例提供一种指纹芯片、制作指纹芯片的方法和电子设备，能够实现超薄指纹芯片。
第一方面，提供了一种指纹芯片，包括：基底，所述基底的厚度大或等于30微米且小于80微米，所述基底上形成有像素阵列，所述像素阵列用于检测入射至手指并经所述手指反射或散射的光信号；光路层，设置在所述基底上方，用于将所述光信号传输至所述像素阵列。
在一种可能的实现方式中，所述基底还包括导电通孔结构，所述导电通孔结构用于电连接所述像素阵列和所述指纹芯片的线路板。
在一种可能的实现方式中，所述导电通孔结构由TSV工艺形成。
在一种可能的实现方式中，所述导电通孔结构包括填充有金属材料的通孔，所述金属材料与所述基底的材料之间由绝缘侧壁电隔离。
在一种可能的实现方式中，所述通孔为垂直通孔或者倾斜通孔。
在一种可能的实现方式中，所述通孔的横截面为矩形、圆形或者梯形。
在一种可能的实现方式中，所述导电通孔结构通过设置在所述基底下表面的电连接层，与所述线路板之间进行电连接。
在一种可能的实现方式中，所述电连接层为金属层或者ACF层。
在一种可能的实现方式中，所述光路层包括微透镜阵列。
在一种可能的实现方式中，所述微透镜阵列的表面镀有保护膜层。
在一种可能的实现方式中，所述保护膜层为绝缘的无机材料层。
在一种可能的实现方式中，所述无机材料为硅氧化物或者硅氮化物。
在一种可能的实现方式中，所述保护膜层的厚度位于0.05微米至1微米之间。
在一种可能的实现方式中，所述光路层还包括至少一个挡光层，所述至少一个挡光层设置在所述微透镜阵列和所述像素阵列之间，其中每个挡光层上设置有与多个微透镜分别对应的多个开孔，经每个微透镜会聚后的所述光信号穿过不同挡光层内与所述微透镜对应的开孔，到达所述像素阵列。
在一种可能的实现方式中，不同挡光层内与相同的微透镜对应的开孔由上至下孔径依次减小。
在一种可能的实现方式中，每个微透镜对应于一个像素，其中，经所述微透镜会聚后的所述光信号穿过不同挡光层内与所述微透镜对应的开孔，到达与所述微透镜对应的像素。
在一种可能的实现方式中，不同挡光层内与相同的微透镜对应的开孔的连线，经过所述微透镜对应的光学感应单元的中心区域。
在一种可能的实现方式中，所述微透镜的聚光面在与其光轴垂直的平面上的投影为矩形或者圆形。
在一种可能的实现方式中，所述光路层包括滤光层，所述滤光层用于过滤非特定波段的光信号。
在一种可能的实现方式中，所述光信号为经所述手指反射的垂直光信号或者倾斜光信号。
第二方面，提供了一种制作指纹芯片的方法，包括：
在晶圆上制作加固层，其中，所述晶圆上形成有多个像素阵列，所述多个像素阵列上方设置有光路层，所述光路层用于将入射至手指并经所述手指 反射的光信号传输至所述多个像素阵列，所述加固层通过胶层接合在所述光路层的上表面；
对具有所述加固层的所述晶圆进行减薄处理；
对具有所述加固层的所述晶圆进行切割，得到多个指纹芯片，其中每个指纹芯片包括一个像素阵列；
去除各个指纹芯片上的所述加固层。
在一种可能的实现方式中，减薄处理后的所述晶圆的厚度位于30微米至100微米之间。
在一种可能的实现方式中，在所述去除各个指纹芯片上的所述加固层之前，所述方法还包括：将每个指纹芯片中的像素阵列与所述指纹芯片的线路板进行电连接。
在一种可能的实现方式中，在所述对具有所述加固层的所述晶圆进行切割之前，所述方法还包括：对减薄后的所述晶圆进行穿过硅片通道TSV处理，得到多个导电通孔结构，其中，所述导电通孔结构用于电连接所述像素阵列和所述线路板。
在一种可能的实现方式中，所述导电通孔结构通过设置在所述晶圆下表面的电连接层，与所述线路板之间电连接。
在一种可能的实现方式中，所述电连接层为金属层或者ACF层。
在一种可能的实现方式中，所述导电通孔结构包括填充有金属材料的通孔，所述金属材料与所述晶圆的材料之间由绝缘侧壁电隔离。
在一种可能的实现方式中，所述通孔为垂直通孔或者倾斜通孔。
在一种可能的实现方式中，所述通孔的横截面为矩形、圆形或者梯形。
在一种可能的实现方式中，所述光路层包括多个微透镜阵列，所述加固层通过所述胶层接合至所述多个微透镜阵列。
在一种可能的实现方式中，在所述在晶圆上制作加固层之前，所述方法还包括：在每个微透镜阵列的表面制作保护膜层，其中，所述胶层覆盖在所述多个微透镜阵列的保护膜层上。
在一种可能的实现方式中，所述保护膜层为绝缘的无机材料层。
在一种可能的实现方式中，所述无机材料为硅氧化物或者硅氮化物。
在一种可能的实现方式中，所述保护膜层的厚度位于0.05微米至1微米。
在一种可能的实现方式中，所述微透镜阵列中每个微透镜的聚光面在与 其光轴垂直的平面上的投影为矩形或者圆形。
在一种可能的实现方式中，所述光路层还包括至少一个挡光层，所述至少一个挡光层设置在所述微透镜阵列和所述像素阵列之间，其中每个挡光层上设置有与多个微透镜分别对应的多个开孔，经每个微透镜会聚后的所述光信号穿过不同挡光层内与所述微透镜对应的开孔，到达所述像素阵列。
在一种可能的实现方式中，不同挡光层内与相同的微透镜对应的开孔由上至下孔径依次减小。
在一种可能的实现方式中，每个微透镜对应于一个像素，其中，经所述微透镜会聚后的所述光信号穿过不同挡光层内与所述微透镜对应的开孔，到达与所述微透镜对应的像素。
在一种可能的实现方式中，所述去除各个指纹芯片上的所述加固层，包括：使用特定溶剂将所述加固层与所述光路层之间的所述胶层溶解，以使各个指纹芯片与其加固层分离。
在一种可能的实现方式中，所述去除各个指纹芯片上的所述加固层，包括：通过激光将所述加固层与所述光路层之间的所述胶层分解，以使各个指纹芯片与其加固层分离；使用特定溶剂将未被激光分解的残留胶体溶解。
在一种可能的实现方式中，所述胶层为临时键合胶层。
在一种可能的实现方式中，所述临时键合胶层的厚度位于15微米至50微米之间。
在一种可能的实现方式中，所述加固层为玻璃层。
在一种可能的实现方式中，所述加固层的厚度位于200微米至1000微米。
第三方面，提供了一种电子设备，包括第一方面或第一方面的任意可能的实现方式中的指纹芯片。
基于上述技术方案，在制作指纹芯片的过程中，使用固定层对晶圆提供机械支撑，并在指纹芯片制作完成后才将该固定层去除，能够避免晶圆在后续工艺过程中由于太薄而引起翘曲等问题，实现了制作超薄指纹芯片的可能。基于该方法得到的指纹芯片的基底的厚度能够达到30微米至100微米之间。
附图说明
图1(a)是本申请可以适用的电子设备的结构示意图。
图1(b)是图1(a)所示的电子设备沿A-A’方向的剖面示意图。
图2是本申请实施例的制作指纹芯片的方法的示意性流程图。
图3(a)至图3(h)是图2所示的制作指纹芯片的方法的一种可能的工艺流程图。
图4是本申请实施例的指纹芯片的示意性框图。
图5是图4所示的指纹芯片的一种可能的结构示意图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
应理解，本申请实施例可以应用于指纹系统，包括但不限于光学、超声波或其他指纹识别系统和基于光学、超声波或其他指纹成像的医疗诊断产品，本申请实施例仅以光学指纹系统为例进行说明，但不应对本申请实施例构成任何限定，本申请实施例同样适用于其他采用光学、超声波或其他成像技术的系统等。
作为一种常见的应用场景，本申请实施例提供的光学指纹系统可以应用在智能手机、平板电脑以及其他具有显示屏的移动终端或者其他电子设备；更具体地，在上述电子设备中，指纹模组可以具体为光学指纹模组，其可以设置在显示屏下方的局部区域或者全部区域，从而形成屏下(Under-display或Under-screen)光学指纹系统。或者，所述光学指纹模组也可以部分或者全部集成至所述电子设备的显示屏内部，从而形成屏内(In-display或In-screen)光学指纹系统。
光学屏下指纹识别技术使用从设备显示组件的顶面返回的光来进行指纹感应和其他感应操作。该返回的光携带与该顶面接触的物体(例如手指)的信息，通过采集和检测该返回的光，实现位于显示屏下方的特定光学传感器模块。光学传感器模块的设计可以为通过恰当地配置用于采集和检测返回的光的光学元件来实现期望的光学成像。
图1(a)和图1(b)示出了本申请实施例可以适用的电子设备的示意图。其中，图1(a)为电子设备10的定向示意图，图1(b)为图1(a)所示的电子设备10沿A-A’方向的部分剖面示意图。
所述电子设备10包括显示屏120和光学指纹模组130。其中，所述光学指纹模组130设置在所述显示屏120下方的局部区域。所述光学指纹模组130 包括光学指纹传感器，所述光学指纹传感器包括具有多个光学感应单元131的感应阵列133。所述感应阵列133所在区域或者其感应区域为所述光学指纹模组130的指纹检测区域103(也称为指纹采集区域、指纹识别区域等)。如图1(a)所示，所述指纹检测区域103位于所述显示屏120的显示区域之中。在一种替代实施例中，所述光学指纹模组130还可以设置在其他位置，比如所述显示屏120的侧面或者所述电子设备10的边缘非透光区域，并通过光路设计来将来自所述显示屏120的至少部分显示区域的光信号导引到所述光学指纹模组130，从而使得所述指纹检测区域103实际上位于所述显示屏120的显示区域。
应理解，所述指纹检测区域103的面积可以与所述光学指纹模组130的感应阵列133的面积不同，例如通过例如透镜成像的光路设计、反射式折叠光路设计或者其他光线汇聚或者反射等光路设计，可以使得所述光学指纹模组130的指纹检测区域103的面积大于所述光学指纹模组130的感应阵列133的面积。在其他替代实现方式中，如果采用例如光线准直方式进行光路引导，所述光学指纹模组130的指纹检测区域103也可以设计成与所述光学指纹模组130的感应阵列的面积基本一致。
因此，使用者在需要对所述电子设备10进行解锁或者其他指纹验证的时候，只需要将手指按压在位于所述显示屏120的指纹检测区域103，便可以实现指纹输入。由于指纹检测可以在屏内实现，因此采用上述结构的电子设备10无需其正面专门预留空间来设置指纹按键(比如Home键)，从而可以采用全面屏方案，即所述显示屏120的显示区域可以基本扩展到整个电子设备10的正面。
作为一种可选的实现方式，如图1(b)所示，所述光学指纹模组130包括光检测部分134和光学组件132。所述光检测部分134包括所述感应阵列133以及与所述感应阵列133电性连接的读取电路及其他辅助电路，其可以在通过半导体工艺制作在一个芯片(Die)上，比如光学成像芯片或者光学指纹传感器。所述感应阵列133具体为光探测器(Photodetector)阵列，其包括多个呈阵列式分布的光探测器，所述光探测器可以作为如上所述的光学感应单元。所述光学组件132可以设置在所述光检测部分134的感应阵列133的上方，其可以具体包括滤光层(Filter)、导光层或光路引导结构、以及其他光学元件，所述滤光层可以用于滤除穿透手指的环境光，而所述导光 层或光路引导结构主要用于从手指表面反射回来的反射光导引至所述感应阵列133进行光学检测。
在具体实现上，所述光学组件132可以与所述光检测部分134封装操作在同一个光学指纹部件。比如，所述光学组件132可以与所述光学检测部分134封装操作在同一个光学指纹芯片，也可以将所述光学组件132设置在所述光检测部分134所在的指纹芯片外部，比如将所述光学组件132贴合在所述指纹芯片的上方，或者将所述光学组件132的部分元件集成在上述指纹芯片之中。
其中，所述光学组件132的导光层或者光路引导结构有多种实现方案，比如，所述导光层可以具体为在半导体硅片制作而成的准直器(Collimator)层，其具有多个准直单元或者微孔阵列，所述准直单元可以具体为小孔，从手指反射回来的反射光中，垂直入射到所述准直单元的光线可以穿过并被其下方的光学感应单元接收，而入射角度过大的光线在所述准直单元内部经过多次反射被衰减掉，因此每一个光学感应单元基本只能接收到其正上方的指纹纹路反射回来的反射光，从而所述感应阵列133便可以检测出手指的指纹图像。
在另一种实现方式中，所述导光层或者光路引导结构也可以为光学透镜(Lens)层，其具有一个或多个透镜单元，比如一个或多个非球面透镜组成的透镜组，其用于将从手指反射回来的反射光汇聚到其下方的光检测部分134的感应阵列133，以使得所述感应阵列133可以基于所述反射光进行成像，从而得到所述手指的指纹图像。可选地，所述光学透镜层在所述透镜单元的光路中还可以形成有针孔，所述针孔可以配合所述光学透镜层扩大所述光学指纹模组130的视场，以提高所述光学指纹模组130的指纹成像效果。
在其他实现方式中，所述导光层或者光路引导结构也可以具体采用微透镜(Micro-Lens)层，所述微透镜层具有由多个微透镜形成的微透镜阵列，其可以通过半导体生长工艺或者其他工艺形成在所述光检测部分134的感应阵列133上方，并且每一个微透镜可以分别对应于所述感应阵列133的其中一个感应单元。并且，所述微透镜层和所述感应单元之间还可以形成其他光学膜层，比如介质层或者钝化层。更具体地，所述微透镜层和所述感应单元之间还可以包括具有微孔的挡光层(或称为遮光层、阻光层等)，其中所述微孔形成在其对应的微透镜和感应单元之间，所述挡光层可以阻挡相邻微透 镜和感应单元之间的光学干扰，并使得所述感应单元所对应的光线通过所述微透镜汇聚到所述微孔内部并经由所述微孔传输到所述感应单元以进行光学指纹成像。
应理解，上述导光层或者光路引导结构的几种实现方案可以单独使用也可以结合使用。比如，可以在所述准直器层或者所述光学透镜层的上方或下方进一步设置微透镜层。当然，在所述准直器层或者所述光学透镜层与所述微透镜层结合使用时，其具体叠层结构或者光路可能需要按照实际需要进行调整。
作为一种可选的实现方式，所述显示屏120可以采用具有自发光显示单元的显示屏，比如有机发光二极管(Organic Light-Emitting Diode，OLED)显示屏或者微型发光二极管(Micro-LED)显示屏。以采用OLED显示屏为例，所述光学指纹模组130可以利用所述OLED显示屏120位于所述指纹检测区域103的显示单元(即OLED光源)作为光学指纹检测的激励光源。当手指140按压在所述指纹检测区域103时，显示屏120向所述指纹检测区域103上方的目标手指140发出一束光111，该光111在手指140的表面发生反射形成反射光或者经过所述手指140内部散射而形成散射光。在相关专利申请中，为便于描述，上述反射光和散射光统称为反射光。由于指纹的脊(ridge)141与谷(valley)142对于光的反射能力不同，因此，来自指纹脊的反射光151和来自指纹谷的反射光152具有不同的光强，反射光经过光学组件132后，被光学指纹模组130中的感应阵列133所接收并转换为相应的电信号，即指纹检测信号；基于所述指纹检测信号便可以获得指纹图像数据，并且可以进一步进行指纹匹配验证，从而在电子设备10实现光学指纹识别功能。
在其他实现方式中，所述光学指纹模组130也可以采用内置光源或者外置光源来提供用于进行指纹检测的光信号。在这种情况下，所述光学指纹模组130可以适用于非自发光显示屏，比如液晶显示屏或者其他的被动发光显示屏。以应用在具有背光模组和液晶面板的液晶显示屏为例，为支持液晶显示屏的屏下指纹检测，所述电子设备10的光学指纹系统还可以包括用于光学指纹检测的激励光源，所述激励光源可以具体为红外光源或者特定波长非可见光的光源，其可以设置在所述液晶显示屏的背光模组下方或者设置在所述电子设备10的保护盖板下方的边缘区域，而所述光学指纹模组130可以 设置液晶面板或者保护盖板的边缘区域下方并通过光路引导以使得指纹检测光可以到达所述光学指纹模组130；或者，所述光学指纹模组130也可以设置在所述背光模组下方，且所述背光模组通过对扩散片、增亮片、反射片等膜层进行开孔或者其他光学设计以允许指纹检测光穿过液晶面板和背光模组并到达所述光学指纹模组130。当采用所述光学指纹模组130采用内置光源或者外置光源来提供用于进行指纹检测的光信号时，其检测原理与上面描述内容是一致的。
应理解，在具体实现上，所述电子设备10还可以包括透明保护盖板，所述盖板可以为玻璃盖板或者蓝宝石盖板，其位于所述显示屏120的上方并覆盖所述电子设备10的正面。因此，本申请实施例中，所谓的手指按压在所述显示屏120实际上是指按压在所述显示屏120上方的盖板或者覆盖所述盖板的保护层表面。
另一方面，在某些实现方式中，所述光学指纹模组130可以仅包括一个光学指纹传感器，此时光学指纹模组130的指纹检测区域103的面积较小且位置固定，因此用户在进行指纹输入时需要将手指按压到所述指纹检测区域103的特定位置，否则光学指纹模组130可能无法采集到指纹图像而造成用户体验不佳。在其他替代实施例中，所述光学指纹模组130可以具体包括多个光学指纹传感器。所述多个光学指纹传感器可以通过拼接方式并排设置在所述显示屏120的下方，且所述多个光学指纹传感器的感应区域共同构成所述光学指纹模组130的指纹检测区域103。从而所述光学指纹模组130的指纹检测区域103可以扩展到所述显示屏的下半部分的主要区域，即扩展到手指惯常按压区域，从而实现盲按式指纹输入操作。进一步地，当所述光学指纹传感器数量足够时，所述指纹检测区域103还可以扩展到半个显示区域甚至整个显示区域，从而实现半屏或者全屏指纹检测。
指纹芯片作为具有光学指纹识别功能的电子设备的重要组成部分，受其封装方式的影响，其厚度受到了很大的限制。本申请实施例提供了一种制作指纹芯片的方法，能够获得超薄的指纹芯片。
以下，将上述的光学感应单元131也称为像素或者感光像素，将感应阵列133也称为像素阵列，将光学组件132也称为光路层。
图2是本申请实施例的制作指纹芯片的方法的示意性流程图。如图2所示，包括以下步骤中的部分或全部。
在210中，在晶圆上制作加固层。
其中，该晶圆上形成有多个像素阵列，该多个像素阵列上方设置有光路层，该光路层用于将入射至手指并经该手指反射的光信号传输至该多个像素阵列，该加固层通过胶层接合在该光路层的上表面。
该晶圆的材料例如可以是硅等半导体材料。
该晶圆上形成有多个像素阵列，并且该多个像素阵列的上方设置有光路层。该加固层设置在该光路层的上方，例如该加固层可以通过胶层接合在该光路层的上表面。在后续的工艺步骤中，该加固层始终与该晶圆保持连接，从而为该晶圆提供机械支撑，直至独立的指纹芯片制作完成后再去除。
每个像素阵列中包括由例如多个光电二级光形成的多个像素。这些像素阵列的上方设置有光路层，该光路层可以将显示屏上方的手指反射或散射的光信号传输至像素阵列，该光信号中携带该手指的指纹信息，因此根据这些指纹信息可以进行指纹识别。
用于连接该加固层与该光路层的胶层例如可以是临时键合胶层，可以将该胶层涂覆在光路层上，当该胶层固化后，可以实现固定层和光路层之间的有效键合。该胶层在特定溶剂中可以被溶解从而失去键合作用。
该胶层的厚度例如可以位于15微米至50微米之间。
该光路层中可以包括多个微透镜阵列，该加固层通过该胶层接合至该多个微透镜阵列。
可选地，在210之前，即在晶圆上制作加固层之前，该方法还包括：在每个微透镜阵列的表面制作保护膜层，其中，该胶层覆盖在该多个微透镜阵列的保护膜层上。
该微透镜阵列的表面所镀的保护膜层用于保护各个微透镜在后续工艺中不被损伤，此时，该胶层覆盖在该多个微透镜阵列的保护膜层的上表面。该保护膜层可以为采用镀膜方式生长的化学性质稳定的绝缘的无机材料层，例如为硅氧化物或者硅氮化物等。该无机物材料覆盖晶圆上表面的全部微透镜阵列。该保护膜层的厚度例如可以位于0.05微米至1微米。
该光路层中还可以包括其他光学部件，例如挡光层、滤光层等。这些光学部件的具体结构参考下述针对图4和图5的描述。
该加固层例如可以为玻璃层等，用于在制作指纹芯片的过程中对该晶圆进行支撑。该加固层的厚度例如可以位于200微米至1000微米。
在220中，对具有该加固层的该晶圆进行减薄处理。
由于该晶圆上覆盖有加固层，因此能够在该加固层的支撑和稳固下对该晶圆进行减薄处理。该减薄处理例如可以是利用机械研磨、化学衬底刻蚀和化学机械抛光(Chemical Mechanical Polishing，CMP)等方式，从晶圆背面去除晶圆材料来进行该晶圆的减薄。减薄处理后的该晶圆的厚度例如可以位于30微米至250微米之间，进一步地位于30至100微米之间，进一步地位于30至80微米之间，或者大于等于30微米且小于80微米，甚至可以达到更薄。
在230中，对具有该加固层的所述晶圆进行切割，得到多个指纹芯片。
在一个晶圆上可以制作出多个指纹芯片。在对该晶圆进行减薄后，将该晶圆，连同其上方的光路层和与该光路层接合的固定层同时进行切割，得到多个指纹芯片。其中，每个指纹芯片包括一个像素阵列，该像素阵列的上方具有与其对应的光路层。在从该晶圆中分割出各个指纹芯片后，每个指纹芯片上方仍存在该固定层，因此需要将该固定层去除。
在240中，去除各个指纹芯片上的所述加固层。
在基于该晶圆进行指纹芯片的各个制造工艺时，该加固层始终与该晶圆保持连接，从而对该晶圆进行机械支撑，保护该晶圆在加工过程中不被损伤。当形成各个指纹芯片后，才将该加固层去除。
去除各个指纹芯片与其上方的固定层之间的胶层，就可以使各个指纹芯片与其上方的固定层之间分离。
例如，使用特定溶剂将该加固层与该光路层之间的该胶层溶解，以使各个指纹芯片与其加固层分离。
又例如，通过激光或紫外光将该加固层与该光路层之间的该胶层分解，以使各个指纹芯片与其加固层分离；并使用特定溶剂将未被激光分解的残留胶体溶解。
该特定溶剂仅对该胶层进行溶解，而不会对微透镜阵列表面的保护膜层和线路板等部分造成损伤。
可选地，在240之前，即在去除各个指纹芯片上的该加固层之前，该方法还包括：将每个指纹芯片中的像素阵列与该指纹芯片的线路板进行电连接。
例如，可以对减薄后的该晶圆进行穿过硅片通道(Through Silicon Vias，TSV)处理，得到多个导电通孔结构。其中，该导电通孔结构用于电连接该 像素阵列和该线路板。
该TSV工艺例如可以包括通孔的形成、绝缘侧壁的形成、通孔的填充等步骤，具体可以参考相关技术中的TSV工艺，这里不再赘述。
该实施例中，指纹芯片采用导电通孔结构实现指纹芯片的像素阵列与线路板之间的电连接。在得到该多个导线通孔结构后，对该晶圆进行切割，从而得到多个指纹芯片，再通过该导电通孔结构将该像素阵列与该线路板进行电连接，从而完成指纹芯片的封装。因此，可以避免在指纹芯片外部设置连接指纹芯片上表面焊盘和指纹芯片下表面焊盘的封装焊线，克服封装焊线的线弧高度对光学指纹装置厚度的影响，使指纹芯片可以做到更薄。
其中，该导电通孔结构包括填充有金属材料的通孔，该金属材料与所述晶圆的材料之间由绝缘侧壁电隔离。该金属材料例如可以是铝、铜、钨和高分子导体等，其可以通过电镀、金属沉积等方式形成。该绝缘侧壁的材料例如可以是氧化物、氮化硅等。
该导电通孔结构例如可以通过设置在该晶圆下表面的电连接层，与该线路板之间实现电连接。在得到各个指纹芯片后，将该电连接层与该指纹芯片的线路板进行连接。也就是说，该导电通孔结构的一端与晶圆上表面的焊盘之间电连接，另一端与该晶圆下表面的电连接层之间电连接。
该电连接层例如可以是焊盘或异方性导电膜胶(Anisotropic Conductive Film，ACF)层等。
该导电通孔结构中的通孔可以为垂直通孔或者倾斜通孔。当为倾斜通孔时，本申请对该通孔的倾斜角度不做限定，例如可以是与指纹芯片下表面之间成45°-90°之间的夹角。
本申请对该通孔的形状也不做限定，例如该通孔的横截面可以为圆形、矩形、梯形或者其他多边形。
可见，在制作指纹芯片的过程中，使用固定层对晶圆提供机械支撑，并在指纹芯片制作完成后才将该固定层去除，能够避免晶圆在后续工艺过程中由于太薄而引起翘曲等问题，实现了制作超薄指纹芯片的可能。
下面以图3(a)至图3(h)为例，对本申请实施例的制作指纹芯片的方法进行详细描述。
图3(a)至图3(h)中示出了晶圆301、微透镜阵列302、微透镜302上镀的保护膜层303、玻璃层304、用于键合玻璃层304和晶圆301的临时 键合胶层305、导电通孔结构306、电连接层307和线路板308。
应理解，在图3(a)之前的工艺过程中，可以在晶圆301上形成有多个微透镜阵列302，图3(a)至图3(h)仅以两个微透镜阵列为例进行说明。在实际操作中，一个晶圆上可以制作出大量的微透镜阵列302。
在图3(a)中，在微透镜阵列302的上表面，镀上保护膜层303。
在图3(b)中，在形成有微透镜阵列302的晶圆301的上方旋涂临时键合胶层305。其中，该临时键合胶层305覆盖在保护膜层303上。
在图3(c)中，将涂覆有临时键合胶层305的晶圆301与玻璃层304进行键合和固化。至此，该玻璃层304通过临时键合胶层305固定在晶圆301的上方。
在后续的图3(d)至图3(g)所示的工艺过程称为指纹芯片的封装过程，在该过程中，玻璃层304始终与晶圆301保持接合状态。
在图3(d)中，对具有该玻璃层304的晶圆301进行减薄。其中，可以从晶圆301的背部3011的方向将晶圆的材料研磨至所需的厚度。由于有玻璃层304对晶圆301进行支撑和稳固，因此避免了晶圆301的厚度较薄时产生的翘曲的问题，能够实现较薄的晶圆厚度，例如大于或等于30微米且小于80微米。
在图3(e)中，对减薄后的晶圆301进行TSV加工，在晶圆301上形成导电通孔结构306。导电通孔结构306位于微透镜阵列302所在区域之外的区域，其可以将晶圆301的上表面3012与下表面3011之间电连接。其中，晶圆301的下表面3011上设置有电连接层307。导电通孔结构306的一端可以与晶圆301的上表面3012上的焊盘连接，另一端与电连接层307连接。
在图3(f)中，对具有玻璃层304的晶圆301进行切割，从而从晶圆301中分割出来多个指纹芯片。应注意，在切割过程中，是对晶圆301以及其上方的临时键合胶层305和玻璃层304一起进行切割，从而分割出多个指纹芯片。由于晶圆301的厚度较薄，连同其上方的临时键合胶层305和玻璃层304一起进行切割能够保护晶圆301在切割过程中不会发生形变，从而保障了分割出来的指纹芯片的质量。其中，每个指纹芯片包括一个微透镜阵列302，该微透镜阵列用于将光信号传输至其下方的像素阵列，该像素阵列在此处未示出。
在图3(g)中，将得到的指纹芯片连接至其线路板308。可以将电连接 层307与线路板308连接，从而完成指纹芯片的封装。图3(g)中所示为封装完成的一个指纹芯片，此时，该指纹芯片的上方还连接有玻璃层304。
在图3(h)中，将图3(g)中得到的整个指纹芯片浸泡在可以溶解临时键合胶层305的特定溶剂中，从而将临时键合胶层305溶解，使得玻璃层304与指纹芯片分离；或者，可以根据临时键合材料选择使用激光或紫外光分解临时键合胶层305，以使玻璃层304与指纹芯片分离，之后再使用可使用可以溶解临时键合胶层305的特定溶剂清除指纹芯片表面上残留的临时键合材料，最终得到图3(h)所示的指纹芯片。
晶圆301上方设置有光路层，在3(a)至图3(h)中，仅示出了该光路层中的微透镜阵列302。该光路层中还可以包括例如滤光层、挡光层等其他光学器件。并且，晶圆301和玻璃层304之间还可以设置其他结构，例如具有其他电气结构的层。为了简洁，这里均未示出。
另外，晶圆301中还形成有多个像素阵列，其中每个像素阵列可以对应于一个微透镜阵列，该像素阵列用于检测其对应的微透镜阵列302传输下来的光信号。为了简洁，图3(a)至图3(h)中均未示出像素阵列。
该像素阵列包括多个像素，每个像素可以用于检测光信号，并将其转换为电信号。该像素例如可以是光电二极管等。
本申请实施例中，需要在指纹芯片制作完成之后，再去除固定层。即得到封装好的指纹芯片后才去除固定层。但是并不限定指纹芯片的封装过程中的各个步骤的顺序。例如，可以先进行TSV加工再对晶圆进行减薄，也可以先减薄再进行TSV加工。
本申请还提供了基于图2所示的方法制作的指纹芯片。方法实施例所描述的各个技术特征也适用于以下装置实施例。如图4所示，该指纹芯片400包括基底410和光路层420。
其中，基底410的厚度位于30微米至100微米之间，基底410上形成有像素阵列，该像素阵列用于检测入射至手指并经该手指反射或散射的光信号。光路层420设置在基底410的上方，用于将手指反射或散射的该光信号传输至该像素阵列。
用于照射该手指的光源例如可以是OLED显示屏等自发光显示屏内的发光单元，也可以是外置的其他激励光源，这里不做限定。
该光信号可以为经该手指反射的垂直光信号或者倾斜光信号。其中，由 于倾斜入射至手指的光信号经所述手指反射后的光强明显提升，因此能够提高指纹谷和脊的对比度，对特殊手指例如干手指具有更好的指纹识别性能。
可选地，指纹芯片400还包括线路板430，线路板430例如包括该像素阵列的辅助电路和处理电路等。
基底410可以由前述的晶圆，例如图3(a)至图3(h)中的晶圆301形成，基底410例如可以是硅基底。可以看出，通过图2所示的方法形成的基底410的厚度能够达到30微米至100微米，例如通常可以大于或等于30微米且小于80微米。从而实现了超薄指纹芯片，给手机厂商带来更大的整机结构设计空间。其中，指纹芯片400例如可以粘贴在手机的显示屏的下表面，或者通过中框固定在显示屏的下方。
可选地，基底410上还包括导电通孔结构，该导电通孔结构用于电连接该像素阵列和该指纹芯片的线路板430。
该导电通孔结构例如可以由TSV工艺形成。该导电通孔结构为填充有金属材料的通孔，该金属材料与基底410的材料之间由绝缘侧壁电隔离。
该通孔可以为垂直通孔或者倾斜通孔。该通孔的横截面可以为矩形、圆形或者梯形，也可以为其他任何形状。本申请对此均不作限定。
该导电通孔结构的一端与基底410上表面的焊盘连接，另一端通过基底410下表面的电连接层与线路板430之间进行电连接。该电连接层例如可以是金属层或者ACF层。
光路层420可以包括微透镜阵列。该微透镜阵列中的各个微透镜的聚光面在与其光轴垂直的平面上的投影可以为圆形或者矩形。其中，该微透镜阵列中的微透镜为矩形微透镜时，相比于圆形透镜具有更好的聚光面积占比，因此能够使像素阵列采集到更多的指纹信息，提高指纹识别性能。
该微透镜阵列的表面例如可以镀有保护膜层。该保护膜层可以为采用镀膜方式生长的化学性质稳定的绝缘的无机材料层，例如为硅氧化物或者硅氮化物等。该无机物材料覆盖全部微透镜阵列的上表面。该保护膜层的厚度例如可以位于0.05微米至1微米。
可选地，光路层420还可以包括至少一个挡光层，该至少一个挡光层依次设置在该微透镜阵列和该像素阵列之间，其中每个挡光层上设置有与多个微透镜分别对应的多个开孔，经每个微透镜会聚后的该光信号穿过不同挡光层内与该微透镜对应的开孔，到达该像素阵列。
每个挡光层内的开孔，除了实现光路引导，还可以有效地防止光线串扰，阻挡杂光，使得手指反射的满足一定预设角度的倾斜光线能够经过挡光层达到像素阵列。本申请实施例对挡光层的数量不做限定。挡光层的数量太多会增加指纹识别装置的厚度和复杂度，而挡光层的数量太少会带来较多的干扰光，影响成像效果。在实际使用时，可以根据需求设置合理数量的挡光层。
微透镜阵列中的每个微透镜对应于像素阵列中的一个像素，经该微透镜会聚后的该光信号穿过不同挡光层内与该微透镜对应的开孔，到达与该微透镜对应的像素。
当采用手指反射的倾斜光进行指纹识别时，不同挡光层内与相同的微透镜对应的开孔之间的连线的倾斜角度，与该倾斜光信号的倾斜角度相同。为了对手指反射的倾斜光线进行传输，与同一微透镜对应的位于不同挡光层内的开孔之间应当具有横向偏移，并且位于不同挡光层内的这些开孔的连线应当经过对应的像素，这样才能够使该倾斜光信号能够达到该像素。
另外，不同挡光层内与相同的微透镜对应的开孔可以由上至下孔径依次减小。
由于微透镜对光线具有会聚作用，越往下传输则被汇会聚形成的光束的角度越窄。因此，可选地，不同挡光层内与相同的微透镜对应的开孔由上至下孔径依次减小，从而到达像素的光束为窄光束，实现对光线的窄角度接收，在保证准直度的同时还可以有效衰减不需要的光线，进一步提高指纹芯片采集到的光学指纹图像的清晰度。
可选地，光路层420还可以包括滤光层，该滤光层用于过滤非特定波段的光信号，以使满足波长条件的光线能够到达像素，而不满足波长条件的光线被过滤掉，例如可以过滤红外波段的光线，而透过可见光波段的光线。该滤光层可以设置在微透镜阵列的上方，并通过透明胶层与微透镜阵列连接在一起；或者该滤光层也可以设置在该微透镜阵列的下方；或者也可以在微透镜阵列的上方和/或下方设置至少一个滤光层。
图5示出了图4的指纹芯片的一种可能的结构示意图。图5示出了基底510、光路层520和线路板530。
其中，基底510上形成有像素阵列511和导电通孔结构512。像素阵列511通过驱动电路513电连接至焊盘5121。基底510的下表面依次设置有绝缘层514、重布线层531和电连接层532。导电通孔结构512的两端分别与 焊盘5121和焊盘5122连接，焊盘5122与基底510下表面的重布线层531和电连接层532连接，电连接层532与线路板530之间连接，从而使得像素阵列511能够电连接至线路板530。
光路层520包括滤光层521、滤光层525、挡光层523和微透镜阵列526。其中，滤光层521与挡光层523之间通过介质层或胶层522连接，滤光层525与挡光层523之间通过介质层或胶层524连接，微透镜阵列526位于滤光层525上方。滤光层521和滤光层525可以分别用来过滤不同波段的光线，从而使满足要求的光线传输至像素阵列511。入射至手指并经该手指反射或散射的光信号，被微透镜阵列526会聚，并经过挡光层523中的小孔传输至像素阵列511。像素阵列511检测到该光信号后，可以将光信号转换成电信号并进一步用于进行指纹识别。
图5中的指纹芯片的四周可以通过点胶515进行加固。
本申请实施例的指纹芯片具有较薄的厚度，例如可以达到150微米至400微米。其中，基底510的厚度可以达到大于或等于30微米且小于80微米的范围。
本申请实施例还提供了一种电子设备，该电子设备包括上述本申请各种实施例中的指纹芯片。
可选地，该电子设备还包括显示屏，该显示屏可以为普通的非折叠显示屏，该显示屏也可以为可折叠显示屏，或称为柔性显示屏。
作为示例而非限定，本申请实施例中的电子设备可以为终端设备、手机、平板电脑、笔记本电脑、台式机电脑、游戏设备、车载电子设备或穿戴式智能设备等便携式或移动计算设备，以及电子数据库、汽车、银行自动柜员机(Automated Teller Machine，ATM)等其他电子设备。该穿戴式智能设备包括功能全、尺寸大、可不依赖智能手机实现完整或部分的功能，例如：智能手表或智能眼镜等，以及只专注于某一类应用功能，需要和其它设备如智能手机配合使用，如各类进行体征监测的智能手环、智能首饰等设备。
需要说明的是，在不冲突的前提下，本申请描述的各个实施例和/或各个实施例中的技术特征可以任意的相互组合，组合之后得到的技术方案也应落入本申请的保护范围。
应理解，本申请实施例中的具体的例子只是为了帮助本领域技术人员更好地理解本申请实施例，而非限制本申请实施例的范围，本领域技术人员可 以在上述实施例的基础上进行各种改进和变形，而这些改进或者变形均落在本申请的保护范围内。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (45)

  1. 一种指纹芯片，其特征在于，包括：
    基底，所述基底的厚度大于或等于30微米且小于80微米，所述基底上形成有像素阵列，所述像素阵列用于检测入射至手指并经所述手指反射或散射的光信号；
    光路层，设置在所述基底上方，用于将所述光信号传输至所述像素阵列。
  2. 根据权利要求1所述的指纹芯片，其特征在于，所述基底还包括导电通孔结构，所述导电通孔结构用于电连接所述像素阵列和所述指纹芯片的线路板。
  3. 根据权利要求2所述的指纹芯片，其特征在于，所述导电通孔结构由穿过硅片通道TSV工艺形成。
  4. 根据权利要求2或3所述的指纹芯片，其特征在于，所述导电通孔结构包括填充有金属材料的通孔，所述金属材料与所述基底的材料之间由绝缘侧壁电隔离。
  5. 根据权利要求4所述的指纹芯片，其特征在于，所述通孔为垂直通孔或者倾斜通孔。
  6. 根据权利要求4或5所述的指纹芯片，其特征在于，所述通孔的横截面为矩形、圆形或者梯形。
  7. 根据权利要求2至6中任一项所述的指纹芯片，其特征在于，所述导电通孔结构通过设置在所述基底下表面的电连接层，与所述线路板之间进行电连接。
  8. 根据权利要求7所述的指纹芯片，其特征在于，所述电连接层为金属层或者异方性导电膜胶ACF层。
  9. 根据权利要求1至8中任一项所述的指纹芯片，其特征在于，所述光路层包括微透镜阵列。
  10. 根据权利要求9所述的指纹芯片，其特征在于，所述微透镜阵列的表面镀有保护膜层。
  11. 根据权利要求10所述的指纹芯片，其特征在于，所述保护膜层为绝缘的无机材料层。
  12. 根据权利要求11所述的指纹芯片，其特征在于，所述无机材料为硅氧化物或者硅氮化物。
  13. 根据权利要求10至12中任一项所述的指纹芯片，其特征在于，所述保护膜层的厚度位于0.05微米至1微米之间。
  14. 根据权利要求9至13中任一项所述的指纹芯片，其特征在于，所述光路层还包括至少一个挡光层，所述至少一个挡光层设置在所述微透镜阵列和所述像素阵列之间，其中每个挡光层上设置有与多个微透镜分别对应的多个开孔，经每个微透镜会聚后的所述光信号穿过不同挡光层内与所述微透镜对应的开孔，到达所述像素阵列。
  15. 根据权利要求14所述的指纹芯片，其特征在于，不同挡光层内与相同的微透镜对应的开孔由上至下孔径依次减小。
  16. 根据权利要求14或15所述的指纹芯片，其特征在于，每个微透镜对应于一个像素，其中，经所述微透镜会聚后的所述光信号穿过不同挡光层内与所述微透镜对应的开孔，到达与所述微透镜对应的像素。
  17. 根据权利要求16所述的指纹芯片，其特征在于，不同挡光层内与相同的微透镜对应的开孔的连线，经过所述微透镜对应的像素的中心区域。
  18. 根据权利要求9至17中任一项所述的指纹芯片，其特征在于，所述微透镜的聚光面在与其光轴垂直的平面上的投影为矩形或者圆形。
  19. 根据权利要求1至18中任一项所述的指纹芯片，其特征在于，所述光路层包括滤光层，所述滤光层用于过滤非特定波段的光信号。
  20. 根据权利要求1至19中任一项所述的指纹芯片，其特征在于，所述光信号为经所述手指反射的垂直光信号或者倾斜光信号。
  21. 一种制作指纹芯片的方法，其特征在于，包括：
    在晶圆上制作加固层，其中，所述晶圆上形成有多个像素阵列，所述多个像素阵列上方设置有光路层，所述光路层用于将入射至手指并经所述手指反射的光信号传输至所述多个像素阵列，所述加固层通过胶层接合在所述光路层的上表面；
    对具有所述加固层的所述晶圆进行减薄处理；
    对具有所述加固层的所述晶圆进行切割，得到多个指纹芯片，其中每个指纹芯片包括一个像素阵列；
    去除各个指纹芯片上的所述加固层。
  22. 根据权利要求21所述的方法，其特征在于，减薄处理后的所述晶圆的厚度大于或等于30微米且小于80微米。
  23. 根据权利要求21或22所述的方法，其特征在于，在所述去除各个指纹芯片上的所述加固层之前，所述方法还包括：
    将每个指纹芯片中的像素阵列与所述指纹芯片的线路板进行电连接。
  24. 根据权利要求23所述的方法，其特征在于，在所述对具有所述加固层的所述晶圆进行切割之前，所述方法还包括：
    对减薄后的所述晶圆进行穿过硅片通道TSV处理，得到多个导电通孔结构，其中，所述导电通孔结构用于电连接所述像素阵列和所述线路板。
  25. 根据权利要求24所述的方法，其特征在于，所述导电通孔结构通过设置在所述晶圆下表面的电连接层，与所述线路板之间电连接。
  26. 根据权利要求25所述的方法，其特征在于，所述电连接层为金属层或者异方性导电膜胶ACF层。
  27. 根据权利要求24至26中任一项所述的方法，其特征在于，所述导电通孔结构包括填充有金属材料的通孔，所述金属材料与所述晶圆的材料之间由绝缘侧壁电隔离。
  28. 根据权利要求27所述的方法，其特征在于，所述通孔为垂直通孔或者倾斜通孔。
  29. 根据权利要求27或28所述的方法，其特征在于，所述通孔的横截面为矩形、圆形或者梯形。
  30. 根据权利要求21至29中任一项所述的方法，其特征在于，所述光路层包括多个微透镜阵列，所述加固层通过所述胶层接合至所述多个微透镜阵列。
  31. 根据权利要求30所述的方法，其特征在于，在所述在晶圆上制作加固层之前，所述方法还包括：
    在每个微透镜阵列的表面制作保护膜层，其中，所述胶层覆盖在所述多个微透镜阵列的保护膜层上。
  32. 根据权利要求31所述的方法，其特征在于，所述保护膜层为绝缘的无机材料层。
  33. 根据权利要求32所述的方法，其特征在于，所述无机材料为硅氧化物或者硅氮化物。
  34. 根据权利要求30至33中任一项所述的方法，其特征在于，所述保护膜层的厚度位于0.05微米至1微米。
  35. 根据权利要求30至34中任一项所述的方法，其特征在于，所述微透镜阵列中每个微透镜的聚光面在与其光轴垂直的平面上的投影为矩形或者圆形。
  36. 根据权利要求30至35中任一项所述的方法，其特征在于，所述光路层还包括至少一个挡光层，所述至少一个挡光层设置在所述微透镜阵列和所述像素阵列之间，其中每个挡光层上设置有与多个微透镜分别对应的多个开孔，经每个微透镜会聚后的所述光信号穿过不同挡光层内与所述微透镜对应的开孔，到达所述像素阵列。
  37. 根据权利要求36所述的方法，其特征在于，不同挡光层内与相同的微透镜对应的开孔由上至下孔径依次减小。
  38. 根据权利要求36或37所述的方法，其特征在于，每个微透镜对应于一个像素，其中，经所述微透镜会聚后的所述光信号穿过不同挡光层内与所述微透镜对应的开孔，到达与所述微透镜对应的像素。
  39. 根据权利要求21至38中任一项所述的方法，其特征在于，所述去除各个指纹芯片上的所述加固层，包括：
    使用特定溶剂将所述加固层与所述光路层之间的所述胶层溶解，以使各个指纹芯片与其加固层分离。
  40. 根据权利要求21至38中任一项所述的方法，其特征在于，所述去除各个指纹芯片上的所述加固层，包括：
    通过激光将所述加固层与所述光路层之间的所述胶层分解，以使各个指纹芯片与其加固层分离；
    使用特定溶剂将未被激光分解的残留胶体溶解。
  41. 根据权利要求21至40中任一项所述的方法，其特征在于，所述胶层为临时键合胶层。
  42. 根据权利要求41所述的方法，其特征在于，所述临时键合胶层的厚度位于15微米至50微米之间。
  43. 根据权利要求21至42中任一项所述的方法，其特征在于，所述加固层为玻璃层。
  44. 根据权利要求21至43中任一项所述的方法，其特征在于，所述加固层的厚度位于200微米至1000微米。
  45. 一种电子设备，其特征在于，所述电子设备包括根据权利要求1至 20中任一项所述的指纹芯片。
PCT/CN2019/093395 2019-06-05 2019-06-27 指纹芯片、制作指纹芯片的方法和电子设备 WO2020244006A1 (zh)

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