WO2020150938A1 - 光电传感器及其制备方法 - Google Patents

光电传感器及其制备方法 Download PDF

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Publication number
WO2020150938A1
WO2020150938A1 PCT/CN2019/072864 CN2019072864W WO2020150938A1 WO 2020150938 A1 WO2020150938 A1 WO 2020150938A1 CN 2019072864 W CN2019072864 W CN 2019072864W WO 2020150938 A1 WO2020150938 A1 WO 2020150938A1
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WIPO (PCT)
Prior art keywords
photodiode
light
layer
reflective structure
insulating layer
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PCT/CN2019/072864
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English (en)
French (fr)
Inventor
王文轩
沈健
姚国峰
李运宁
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深圳市汇顶科技股份有限公司
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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 CN201980000122.1A priority Critical patent/CN109863509B/zh
Priority to PCT/CN2019/072864 priority patent/WO2020150938A1/zh
Publication of WO2020150938A1 publication Critical patent/WO2020150938A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0216—Coatings

Definitions

  • This application relates to the field of photoelectric sensors, and more specifically, to a photoelectric sensor and a preparation method thereof.
  • the photoelectric sensor is a device that converts light signals into electrical signals based on the photoelectric effect.
  • the thin film transistor photoelectric sensor is a typical photoelectric sensor, which is generally a thin film transistor (TFT) and It is composed of a photodiode (PD) used to convert optical signals into electrical signals.
  • TFT thin film transistor
  • PD photodiode
  • the present application provides a photoelectric sensor and a preparation method thereof, which can improve the collection of the invisible near-infrared light source and the photoelectric conversion efficiency.
  • a photoelectric sensor including: a photodiode and a reflective structure,
  • the reflective structure is arranged outside or inside the photodiode, and/or the reflective structure is arranged below the photodiode, so that incident light from different angles can reach the place after passing through the photodiode. When the reflective structure is reflected, it returns to the photodiode.
  • the photoelectric sensor provided by the embodiment of the application is provided with a reflective structure, which can make incident light incident at different angles be reflected when reaching the reflective structure through the photodiode, and return to the photodiode, which can improve the efficiency of the invisible near-infrared light source. Collect and improve photoelectric conversion efficiency.
  • the reflective structure can be arranged outside or inside the photodiode, or under the photodiode, and can also be arranged outside or inside the photodiode and under the photodiode at the same time, so that the photoelectric The diode area absorbs the reflected light twice or more times, thereby maximizing the light absorption rate.
  • the reflective structure is arranged outside or inside the photodiode along the height direction of the photodiode.
  • a first light-transmitting medium layer is arranged between the reflective structure and the outer wall of the photodiode, and the first The thickness of the light-transmitting medium layer is such that the optical resonance condition for the incident light is satisfied between the photodiode and the reflective structure.
  • the reflective structure is continuously or discretely distributed around the photodiode.
  • the four side surfaces are denoted as a, b, c, and d, and the two bottom surfaces are denoted as e and f, respectively.
  • the reflective structure surrounds the photodiode and is continuously distributed on the outside of the four sides a, b, c, and d.
  • the reflective structure surrounds the photodiode and is discretely distributed on the outer sides of the two sides a and c.
  • the reflective structure surrounds the photodiode and is discretely distributed on the outside of the side surface a. That is, when the reflective structure is discretely distributed, the discrete positions thereof may be randomly generated, or generated based on a specific rule, which is not limited in the embodiment of the present application.
  • the reflective structure if the reflective structure is disposed inside the photodiode, the reflective structure is located in an area close to the outer wall of the photodiode.
  • the reflective structure is located in an area close to the outer wall of the photodiode, which can minimize the impact on the performance of the photodiode.
  • the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.
  • the four side surfaces are denoted as a, b, c, and d, and the two bottom surfaces are denoted as e and f, respectively.
  • the reflective structure is continuously distributed in areas close to the four sides of the photodiode, a, b, c, and d.
  • the reflective structure is discretely distributed in areas close to the b and d sides of the photodiode.
  • the reflective structure is discretely distributed in an area close to the side a of the photodiode. That is, when the reflective structure is discretely distributed, the discrete positions thereof may be randomly generated, or generated based on a specific rule, which is not limited in the embodiment of the present application.
  • the reflective structure is arranged below the photodiode along the horizontal direction of the photodiode.
  • the horizontal direction of the photodiode may be a direction perpendicular to the height direction of the photodiode.
  • a second light-transmitting medium layer is arranged between the reflective structure and the lower surface of the photodiode, and the first The thickness of the two light-transmitting medium layers allows the photodiode and the reflective structure to satisfy the optical resonance condition for the incident light.
  • the reflective structure is also used to block light from entering the photodiode from below the photodiode.
  • the lower electrode of the photodiode is located between the photodiode and the reflective structure, and the lower electrode of the photodiode is located under the peripheral area of the photodiode to allow the The incident light reaches the reflective structure after passing through the photodiode.
  • the lower electrode of the photodiode is made of non-transparent material. When the lower electrode of the photodiode is located below the peripheral area of the photodiode, it will not affect the incident light to reach the photodiode after passing through the photodiode. Reflection structure.
  • the photosensor further includes a thin film transistor, and the thin film transistor and the photodiode constitute a pixel unit of the photosensor.
  • the photosensor may include at least one pixel unit, and each pixel unit includes a thin film transistor and a photodiode.
  • the thin film transistor includes:
  • the first insulating layer extends below the photodiode, and the portion above the reflective structure forms the second light-transmitting medium layer; the first conductive layer extends to the periphery of the photodiode Below the area to form the lower electrode of the photodiode.
  • the reflective structure, the first insulating layer, and the first conductive layer form a storage capacitor to increase the dynamic range of the photodiode detection.
  • the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.
  • the reflective structure may be a trench structure, and the trench structure is not filled with other materials except air.
  • the reflective material of the reflective structure is metal
  • the incident light is near-infrared light.
  • a method for manufacturing a photoelectric sensor including:
  • a first structure is prepared, wherein the first structure includes a thin film transistor, a photodiode, a first metal layer, a light-transmitting insulating layer, and a substrate.
  • the thin film transistor is located in a first region of the substrate.
  • a metal layer is located in the second region of the substrate, the photodiode is located above the first metal layer, and the light-transmitting insulating layer covers the thin film transistor and the photodiode;
  • a connecting electrode is prepared in the trench structure, and a contact electrode is prepared on the connecting electrode and the light-transmitting insulating layer to connect the photodiode with an external control circuit and/or power supply, and the connecting electrode and The contact electrode is light-transmissive to allow incident light incident at different angles to enter the photodiode;
  • a transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode.
  • the preparing a reflective structure located on the outer side of the photodiode on the transparent insulating layer includes:
  • the reflective structure is prepared on the light-transmitting insulating layer along the height direction of the photodiode.
  • the thickness of the light-transmitting insulating layer between the reflective structure and the outer wall of the photodiode is such that the optical resonance condition between the photodiode and the reflective structure is satisfied.
  • the reflective structure is continuously or discretely distributed around the photodiode.
  • the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.
  • a method for manufacturing a photoelectric sensor including:
  • a first conductive layer is prepared on the first insulating layer and the channel layer, wherein the first conductive layer includes a gap exposing the channel layer to separate the first conductive layer as a source electrode And a drain electrode, the first conductive layer extends to above the first metal layer, and a part of the first insulating layer above the first metal layer is exposed;
  • a connecting electrode is prepared in the trench structure, and a contact electrode is prepared on the connecting electrode and the light-transmitting insulating layer to connect the photodiode with an external control circuit and/or power supply, and the connecting electrode and The contact electrode is light-transmissive to allow incident light incident at different angles to enter the photodiode;
  • a transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode.
  • the thickness of the first insulating layer located between the first metal layer and the lower surface of the photodiode is such that the distance between the photodiode and the first metal layer satisfies Resonance conditions.
  • the method before preparing the light-shielding metal layer, the method further includes:
  • the preparing a light-shielding metal layer on the transparent insulating layer includes:
  • the light-shielding metal layer is prepared on the transparent insulating layer and the reflective structure.
  • the preparing a reflective structure located on the outer side of the photodiode on the transparent insulating layer includes:
  • the reflective structure is prepared on the light-transmitting insulating layer along the height direction of the photodiode.
  • the thickness of the light-transmitting insulating layer located between the reflective structure and the outer wall of the photodiode is such that the photodiode and the reflective structure satisfy an optical resonance condition.
  • the reflective structure is continuously or discretely distributed around the photodiode.
  • the method before preparing the transparent insulating layer, the method further includes:
  • the preparing a light-transmitting insulating layer on the first insulating layer, the first conductive layer, and the photodiode includes:
  • a light-transmitting insulating layer is prepared on the first insulating layer, the first conductive layer, the reflective structure and the photodiode.
  • the preparing a reflective structure on the photodiode includes:
  • the reflection structure is prepared on the photodiode near the outer wall along the height direction of the photodiode.
  • the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.
  • the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.
  • a method for manufacturing a photoelectric sensor including:
  • a first conductive layer is prepared on the first insulating layer and the channel layer, wherein the first conductive layer includes a gap exposing the channel layer to separate the first conductive layer as a source electrode And a drain electrode, the first conductive layer extends above the first metal layer;
  • a connecting electrode is prepared in the trench structure, and a contact electrode is prepared on the connecting electrode and the light-transmitting insulating layer to connect the photodiode with an external control circuit and/or power supply, and the connecting electrode and The contact electrode is light-transmissive to allow incident light incident at different angles to enter the photodiode;
  • a transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode.
  • the preparing a reflective structure on the photodiode includes:
  • the reflection structure is prepared on the photodiode near the outer wall along the height direction of the photodiode.
  • the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.
  • the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.
  • an electronic device including the photoelectric sensor as described in the first aspect and any possible implementation of the first aspect.
  • Fig. 1 is a schematic structural diagram of a terminal device to which an embodiment of the present application is applied.
  • Fig. 2 is a schematic structural diagram of a photoelectric sensor according to an embodiment of the present application.
  • FIG. 3 is a schematic diagram of the absorption ratio of incident light by a photodiode as a function of the thickness of the dielectric layer between the reflective structure and the photodiode.
  • Fig. 4 is a schematic structural diagram of yet another photoelectric sensor according to an embodiment of the present application.
  • Fig. 5 is a schematic structural diagram of still another photoelectric sensor according to an embodiment of the present application.
  • Fig. 6 is a schematic structural diagram of still another photoelectric sensor according to an embodiment of the present application.
  • Fig. 7 is a schematic structural diagram of still another photoelectric sensor according to an embodiment of the present application.
  • Fig. 8 is a schematic diagram of a reflected light path after light enters a photodiode according to an embodiment of the present application.
  • Fig. 9 is a schematic diagram of a reflected light path after light enters a photodiode according to an embodiment of the present application.
  • Fig. 10 is a schematic flowchart of a method for manufacturing a photoelectric sensor according to an embodiment of the present application.
  • 11a to 11g are schematic diagrams of preparing a photoelectric sensor according to an embodiment of the present application.
  • Fig. 12 is a schematic flow chart of yet another method for manufacturing a photoelectric sensor according to an embodiment of the present application.
  • FIGS. 13a to 13q are schematic diagrams of preparing a photoelectric sensor according to another embodiment of the present application.
  • Fig. 14 is a schematic flowchart of still another method for manufacturing a photoelectric sensor according to an embodiment of the present application.
  • the embodiments of the present application can be applied to the field of photoelectric sensors, for example, the field of thin film transistor photoelectric sensors, including but not limited to optical fingerprint identification systems, medical diagnostic products based on optical fingerprint imaging, fingerprint image entry and flatbed scanning devices, this application
  • optical fingerprint identification systems including but not limited to optical fingerprint identification systems, medical diagnostic products based on optical fingerprint imaging, fingerprint image entry and flatbed scanning devices
  • the embodiments only take an optical fingerprint system as an example for description, but should not constitute any limitation to the embodiments of the present application, and the embodiments of the present application are also applicable to other systems using photoelectric sensors.
  • the specific structure of the thin film transistor in the photosensor includes, but is not limited to, bottom-gate thin film transistors and top-gate thin film transistors.
  • the specific materials of the thin film transistors include, but are not limited to, amorphous silicon thin film transistors, Low Temperature Poly-silicon (LTPS) thin film transistors, in principle, as long as the photoelectric sensors including thin film transistor (TFT) switches and photodiodes (PD) manufactured by photoelectric thin film technology are within the scope of this application.
  • LTPS Low Temperature Poly-silicon
  • TFT thin film transistor
  • PD photodiodes manufactured by photoelectric thin film technology are within the scope of this application.
  • the embodiment of this application only takes a bottom-gate thin film transistor as an example for description, but should not constitute any limitation to the embodiment of this application.
  • the embodiment of this application is also applicable to other photoelectric sensors using thin film transistors.
  • 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 terminal devices; more specifically, in the above-mentioned terminal devices, fingerprint identification
  • the device may specifically be an optical fingerprint device, which may be arranged in a partial area or an entire area below the display screen, thereby forming an under-display optical fingerprint system.
  • the fingerprint identification device may be partially or fully integrated into the display screen of the terminal device, thereby forming an in-display optical fingerprint system.
  • FIG. 1 is a schematic structural diagram of a terminal device to which the embodiment of the application can be applied.
  • the terminal device 10 includes a display screen 120 and an optical fingerprint device 130, wherein the optical fingerprint device 130 is arranged below the display screen 120 Local area.
  • the optical fingerprint device 130 includes an optical fingerprint sensor, and the optical fingerprint sensor includes a sensing array 133 having a plurality of optical sensing units 131, and the area where the sensing array is located or its sensing area is the fingerprint detection area of the optical fingerprint device 130 103.
  • the fingerprint detection area 103 is located in the display area of the display screen 120.
  • the optical fingerprint device 130 can 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 terminal device 10, and the optical fingerprint device 130 can be designed to The optical signal of at least part of the display area of the display screen 120 is guided to the optical fingerprint device 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 of the optical fingerprint device 130, for example, through optical path design such as lens imaging, reflective folding optical path design, or other optical path design such as light convergence or reflection, etc.
  • the area of the fingerprint detection area 103 of the optical fingerprint device 130 can be made larger than the area of the sensing array of the optical fingerprint device 130.
  • the fingerprint detection area 103 of the optical fingerprint device 130 may also be designed to be substantially the same as the area of the sensing array of the optical fingerprint device 130.
  • the terminal 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 terminal device 10.
  • the optical fingerprint device 130 includes a light detecting part 134 and an optical component 132.
  • the light detecting part 134 includes the sensor array and is electrically connected to the sensor array.
  • the connected reading circuit and other auxiliary circuits 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 is specifically a photodetector (Photodetector) array, which includes A plurality of photodetectors distributed in an array, the photodetectors can be used as the above-mentioned optical sensing unit; the optical component 132 can be arranged above the sensing array of the photodetecting part 134, which can specifically include The filter layer (Filter), the light guide layer or the light path guide structure and other optical elements, the filter layer can be used to filter out the ambient light penetrating the finger, and the light guide layer or the light path guide structure is mainly used to remove The reflected light reflected from the finger surface is guided to the sensing array for optical detection.
  • the filter layer Finter
  • the light guide layer or the light path guide structure is mainly used to remove The reflected light reflected from the finger surface is guided to the sensing array for optical detection.
  • the optical assembly 132 and the light detecting part 134 may be packaged in the same optical fingerprint component.
  • the optical component 132 and the optical detection part 134 can be packaged in the same optical fingerprint chip, or the optical component 132 can be arranged outside the chip where the optical detection part 134 is located, for example, the optical component 132 is attached above the chip, or some components of the optical assembly 132 are integrated into the 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 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 sensor unit can basically only receive the reflected light reflected by the fingerprint pattern directly above it.
  • the sensor array 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 used to converge the reflected light reflected from the finger to the light detection part 134 below it, so that the sensing array 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 device to improve the optical The fingerprint imaging effect of the fingerprint device 130.
  • 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 of the light detecting part 134, and each microlens may correspond to one of the sensing units of the sensing array.
  • other optical film layers may be formed between the micro lens layer and the sensing unit, such as a dielectric layer or a passivation layer.
  • the micro lens layer and the sensing unit may also include The light-blocking layer of the micro-hole, wherein the micro-hole is formed between its corresponding micro-lens and the sensing unit, the light-blocking layer can block the optical interference between the adjacent micro-lens and the sensing unit, and make the sensing The light corresponding to the unit is condensed into the microhole through the microlens and is transmitted to the sensing unit through the microhole to perform optical fingerprint imaging.
  • a microlens layer can be further provided under the collimator layer or the optical lens layer.
  • the collimator layer or the optical lens layer is used in combination with the microlens layer, its specific laminated structure or optical path may need to be adjusted according to actual needs.
  • the display screen 120 may be 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 Screen.
  • OLED Organic Light-Emitting Diode
  • Micro-LED Micro-LED
  • the optical fingerprint device 130 may use the display unit (ie, an OLED light source) of the OLED display screen 120 located 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. Since the ridge and valley of the fingerprint have different light reflection capabilities, the reflected light 151 from the fingerprint ridge and the generated light 152 from the fingerprint ridge have different light intensities.
  • the reflected light passes through the optical component 132, It is received by the sensor array 134 in the optical fingerprint device 130 and converted into a corresponding electrical signal, that is, a fingerprint detection signal; based on the fingerprint detection signal, fingerprint image data can be obtained, and fingerprint matching verification can be further performed, so that the The terminal device 10 implements an optical fingerprint recognition function.
  • the optical fingerprint device 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 device 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 terminal 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 arranged in the edge area under the protective cover of the terminal device 10, and the The optical fingerprint device 130 can 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 device 130; or, the optical fingerprint device 130 can also be arranged in the backlight module. Under the group, 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 device 130 by opening holes or other optical designs on the film layers such as diffuser, brightness enhancement film, and reflective film. .
  • the optical fingerprint device 130 adopts 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 terminal device 10 further includes 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 terminal.
  • the front of the device 10. because, in the embodiment 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 device 130 may include only one optical fingerprint sensor.
  • the fingerprint detection area 103 of the optical fingerprint device 130 has a small area and a fixed position, so the user is performing fingerprint input At this time, it is necessary to press the finger to a specific position of the fingerprint detection area 103, otherwise the optical fingerprint device 130 may not be able to collect fingerprint images, resulting in poor user experience.
  • the optical fingerprint device 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 multiple optical fingerprint sensors The sensing area of the fingerprint sensor together constitutes the fingerprint detection area 103 of the optical fingerprint device 130.
  • the fingerprint detection area 103 of the optical fingerprint device 130 may include multiple sub-areas, and each sub-area corresponds to the sensing area of one of the optical fingerprint sensors, so that the fingerprint collection area of the optical fingerprint module 130 103 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.
  • the fingerprint detection area 130 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.
  • the embodiment of the present application takes a thin film transistor photoelectric sensor as an example for detailed description.
  • the wavelength of near-infrared light (780-2526nm) is longer than that of visible light (380-780nm)
  • the absorption rate of near-infrared light is at the same time, the infrared wavelength easily penetrates the photodiode structure of the thin film transistor photoelectric sensor, which further reduces the absorption efficiency.
  • the present application provides a reflective structure in the photoelectric sensor.
  • an optical resonant cavity structure optimized for incident light of a specific wavelength is formed, so that infrared light is different.
  • the utilization of wavelength light is maximized, thereby improving the collection of near infrared (NIR) light sources that are invisible to the human eye and improving the photoelectric conversion efficiency.
  • NIR near infrared
  • FIG. 2 shows a schematic diagram of a photoelectric sensor 200 according to an embodiment of the present application.
  • the photo sensor 200 may be a photo sensor based on a thin film transistor, and FIG. 2 is a cross-sectional view thereof.
  • the photosensor 200 may include: a photodiode 210 and a reflective structure 220.
  • the reflective structure 220 is disposed on the outer side of the photodiode 210, so that incident light incident at different angles is reflected when passing through the photodiode 210 and reaches the reflective structure 220, and returns to the photodiode 210 again.
  • the incident light may be visible light and/or infrared light, for example, it may be near-infrared light.
  • the shape of the photodiode 210 may be regular, for example, it may be a cube, a cuboid, a cylinder, etc. Of course, the shape of the photodiode 210 may also be irregular.
  • the photodiode 210 generally has a three-layer structure, which are respectively denoted from top to bottom as: P-type amorphous silicon film, intrinsic amorphous silicon film, N-type amorphous silicon film, and P-type amorphous silicon film as the photoelectric
  • P-type amorphous silicon film P-type amorphous silicon film
  • intrinsic amorphous silicon film N-type amorphous silicon film
  • P-type amorphous silicon film as the photoelectric
  • the anode of the diode 210, the N-type amorphous silicon film as the cathode of the photodiode 210, and the intrinsic amorphous silicon film as the light absorption layer of the photodiode 210.
  • the reflective structure 220 is continuously or discretely distributed around the photodiode 210.
  • the photodiode 210 is a cube
  • the four sides are denoted as a, b, c, and d
  • the two bottom surfaces are denoted as e and f, respectively.
  • the reflective structure 220 surrounds the photodiode 210 and is continuously distributed on the outer side of the four sides a, b, c, and d.
  • the reflective structure 220 surrounds the photodiode 210 and is discretely distributed on the outer sides of the two sides a and c.
  • the reflective structure 220 surrounds the photodiode 210 and is discretely distributed on the outside of the side surface a. That is, when the reflective structure 220 is discretely distributed, the discrete positions thereof may be randomly generated or generated based on a specific rule, which is not limited in the embodiment of the present application.
  • the shape and size of the reflective structure 220 can be set according to actual needs.
  • it can be a columnar or wall-shaped structure with a larger aspect ratio, or for example, a larger aspect ratio.
  • the groove-like structure can be set according to actual needs.
  • it can be a columnar or wall-shaped structure with a larger aspect ratio, or for example, a larger aspect ratio.
  • the groove-like structure can be set according to actual needs.
  • it can be a columnar or wall-shaped structure with a larger aspect ratio, or for example, a larger aspect ratio.
  • the reflective structure 220 is arranged outside the photodiode 210 along the height direction of the photodiode 210.
  • the reflective structure 220 has a large refractive index difference with the surrounding medium, and may have a higher reflectivity in the interface area formed by the reflective structure 220 and the surrounding medium.
  • the reflective material of the reflective structure 220 is at least one of air, metal, silicon dioxide, and composite materials.
  • the reflective structure 220 can be a trench structure, and the trench structure is not filled with other materials except air.
  • a first light-transmitting medium layer is provided between the reflective structure 220 and the outer wall of the photodiode 210, and the thickness of the first light-transmitting medium layer is such that the photodiode 210 and the reflective The structures 220 satisfy the optical resonance condition for the incident light.
  • the conditions for forming optical resonance are: the phase difference between the reflected light on the dielectric layer (the interface between the photodiode and the dielectric layer) and the reflected light on the reflective structure (the interface between the dielectric layer and the reflective structure) is zero or an integer multiple of 2 ⁇ , that is, the formation Standing wave.
  • d is the thickness of the dielectric layer
  • ⁇ is the wavelength of monochromatic light.
  • n d is the refractive index of the dielectric layer
  • n r is the refractive index of the reflective structure
  • k r is the extinction coefficient of the reflective structure.
  • the thickness d1 of the first light-transmitting medium layer is controlled to satisfy a certain condition, so that the photodiode 210 and the The reflective structures 220 satisfy the optical resonance condition for the incident light.
  • the absorption ratio of monochromatic light with a wavelength of 940 nanometers in silicon varies with the thickness d1 of the silicon dioxide dielectric layer as shown in FIG. 3.
  • d1 144.9nm, 468.8nm and 792.6nm
  • the absorption ratio of light (940 nm wavelength) reaches the maximum value of 38.5%.
  • the absorption ratio of the photodiode 210 to this monochromatic light (940 nm wavelength) is only 5%.
  • the photosensor 200 further includes a thin film transistor 230, and the thin film transistor 230 and the photodiode 210 constitute a pixel unit of the photosensor 200.
  • the photosensor 200 may include at least one pixel unit, and each pixel unit includes a thin film transistor and a photodiode.
  • the thin film transistor 230 includes:
  • Gate 231 first insulating layer 232, channel layer 233, first conductive layer 234.
  • the first insulating layer 232 covers the gate 231, the channel layer 233 is located on the first insulating layer 232, and the first conductive layer 234 is located on the channel layer 233 and the gate.
  • the first conductive layer 234 has a gap exposing the channel layer 233 to separate the first conductive layer 234 into a source electrode and a drain electrode.
  • the first insulating layer 232 and the first conductive layer 234 extend below the photodiode 210, and the first conductive layer 234 serves as the lower electrode of the photodiode 210.
  • the material of the gate 231 may be metal, for example, molybdenum, aluminum, or molybdenum aluminum alloy.
  • the material of the first insulating layer 232 may be silicon nitride with light-transmitting properties, silicon oxide, or other transparent dielectric materials or spin-on materials, such as silicon dioxide.
  • the channel layer 233 may be a channel of the ⁇ -Si thin film.
  • the thin film transistor 230 further includes: a second insulating layer 235, wherein the second insulating layer 235 covers the channel layer 233 and the first conductive layer 234 (except The area in contact with the photodiode).
  • the material of the second insulating layer 235 may be silicon nitride or silicon oxide or a spin-on material.
  • the photosensor 200 further includes a first metal layer 240, and the first metal layer 240 is disposed under the photodiode 210 for blocking light from passing through the photodiode 210. Enter the photodiode 210 below.
  • the first insulating layer 232 extends below the photodiode 210 and covers the first metal layer 240.
  • the photosensor 200 further includes a light-transmitting metal layer 250, wherein the light-transmitting metal layer 250 covers a part of the thin film transistor 230 and the photodiode 210.
  • the reflective structure 220 is disposed in the light-transmitting metal layer 250, that is, the light-transmitting insulating layer 250 between the reflective structure 220 and the outer wall of the photodiode 210 is the
  • the thickness of the light-transmitting insulating layer 250 located between the reflective structure 220 and the outer wall of the photodiode 210 can be adjusted so that the distance between the photodiode and the reflective structure is satisfied. Optical resonance conditions.
  • the reflective structure 220 is disposed inside the photodiode 210, so that incident light from different angles reaches the photodiode 210 after passing through the photodiode 210.
  • the reflective structure 220 is reflected, it returns to the photodiode 210 again.
  • the reflective structure 220 is disposed outside the photodiode 210.
  • the reflective structure 220 is disposed inside the photodiode 210.
  • the reflective structure 220 is located in an area close to the outer wall of the photodiode 210.
  • the reflective structure 220 is disposed inside the photodiode 210 along the height direction of the photodiode 210.
  • the amorphous silicon material constituting the photodiode 210 has a large refractive index difference with air or silicon dioxide, when light is irradiated on the interface between the photodiode 210 and the reflective structure 220, a good reflection effect will be produced , Improve light reflectivity.
  • the reflective structure 220 is continuously or discretely distributed in a region close to the outer wall of the photodiode 210.
  • the photodiode 210 is a cube, the four sides are denoted as a, b, c, and d, and the two bottom surfaces are denoted as e and f, respectively.
  • the reflective structure 220 is continuously distributed in the area close to the four sides a, b, c, and d of the photodiode 210.
  • the reflective structure 220 is discretely distributed in areas close to the b and d sides of the photodiode 210.
  • the reflective structure 220 is discretely distributed in an area close to the side a of the photodiode 210. That is, when the reflective structure 220 is discretely distributed, the discrete positions thereof may be randomly generated or generated based on a specific rule, which is not limited in the embodiment of the present application.
  • the first metal layer 240 in the embodiment shown in FIG. 2 also serves as a reflective structure, that is, the reflective structure 220 (the first A metal layer 240) is also disposed under the photodiode 210.
  • the first metal layer 240 causes incident light incident at different angles to be reflected when passing through the photodiode 210 to the first metal layer 240 and return to the photodiode 210.
  • the first insulating layer 232 and the first conductive layer 234 extend below the photodiode 210, and the first conductive layer 234 serves as the photodiode 210 The lower electrode.
  • the first insulating layer 232 is formed of a light-transmissive insulating material, and the first insulating layer 232 extends below the photodiode 210 and covers the first insulating layer.
  • the first conductive layer 234 extends below the peripheral area of the photodiode 210 to allow the incident light to reach the first metal layer 240 after passing through the photodiode 210, and the first A conductive layer 234 serves as the bottom electrode of the photodiode 210. Therefore, incident light incident at some angles passes through the photodiode 210 and reaches the reflective structure 220 and the first metal layer 240 and is reflected, and then returns to the photodiode 210. The incident light incident at certain angles may undergo multiple reflections at the reflective structure 220 and the first metal layer 240, so that the photodiode 210 absorbs the incident light twice or even multiple times, thereby increasing the light absorption rate And Quantum Efficiency (QE).
  • QE Quantum Efficiency
  • the lower electrode of the photodiode 210 is relatively small.
  • the portion of the first insulating layer 232 above the first metal layer 240 forms the second light-transmitting medium layer, that is, it is disposed on the first metal layer 240.
  • the second light-transmitting medium layer between the metal layer 240 and the lower surface of the photodiode 210, and the thickness d2 of the second light-transmitting medium layer is such that there is a gap between the photodiode 210 and the first metal layer 240 The optical resonance condition for the incident light is satisfied.
  • the absorption ratio of monochromatic light with a wavelength of 940 nm in silicon varies with the silicon dioxide dielectric layer (the second light-transmitting medium layer)
  • the reflective structure 220, the first insulating layer 232 and the first conductive layer 234 form a storage capacitor to increase the dynamic range of the photodiode 210 detection.
  • the first conductive layer 234 only extends to the peripheral area of the photodiode 210 below, the storage capacitance formed by the reflective structure 220, the first insulating layer 232, and the first conductive layer 234 is small, and the bottom electrode of the photodiode 210 is also small.
  • higher QE means that more effective signals can be collected, and the capacitance is to a greater extent to increase the dynamic range of detection, so in some scenarios, in order to obtain higher QE can be sacrificed A part of the capacitance, for example, to reduce the extension area of the first conductive layer 234, as long as it can be used as the lower electrode of the photodiode 210.
  • the first metal layer 240 in the embodiment shown in FIG. 4 also serves as a reflective structure, that is, the reflective structure 220 (the first A metal layer 240) is also disposed under the photodiode 210.
  • the first metal layer 240 causes incident light incident at different angles to be reflected when passing through the photodiode 210 to the first metal layer 240 and return to the photodiode 210.
  • the first insulating layer 232 and the first conductive layer 234 extend below the photodiode 210, and the first conductive layer 234 serves as the photodiode 210 The lower electrode.
  • the first insulating layer 232 is formed of a transparent insulating material, and the first insulating layer 232 extends below the photodiode 210 and covers the first insulating layer.
  • the metal layer 240; the first conductive layer 234 extends below the peripheral area of the photodiode 210 to allow the incident light to reach the first metal layer 240 after passing through the photodiode, and the first The conductive layer 234 serves as the lower electrode of the photodiode 210.
  • the portion of the first insulating layer 232 located above the first metal layer 240 forms the second light-transmitting medium layer, that is, it is disposed on the first metal layer 240.
  • the second light-transmitting medium layer between the metal layer 240 and the lower surface of the photodiode 210, and the thickness d2 of the second light-transmitting medium layer is such that there is a gap between the photodiode 210 and the first metal layer 240 The optical resonance condition for the incident light is satisfied.
  • the first metal layer 240 serves as a reflective structure, and the reflective structure 220 is not provided outside or inside the photodiode, that is, the reflective The structure 220 is only disposed under the photodiode 210.
  • the first metal layer 240 causes incident light incident at different angles to be reflected when passing through the photodiode 210 to the first metal layer 240 and return to the photodiode 210.
  • the reflective structure 220 is disposed on the outside of the photodiode 210, and the first metal layer 240 serves as a reflective structure.
  • the reflective structure 220 is only disposed under the photodiode 210, that is, only the first metal layer 240 serves as a reflective structure.
  • the photoelectric sensor 200 may further include:
  • the light-shielding metal layer 260, the connection electrode 270, the contact electrode 280, the insulating protective layer 290, and the substrate 20 are the light-shielding metal layer 260, the connection electrode 270, the contact electrode 280, the insulating protective layer 290, and the substrate 20.
  • the light-shielding metal layer 260 covers the light-transmitting insulating layer 250; the connecting electrode 270 is located on the photodiode 210; the contact electrode 280 is located on the connecting electrode 270 and covering the light-transmitting insulating layer In a partial area of the layer 250, the contact electrode 280 connects the photodiode 210 with an external control circuit and/or power source, and the connection electrode 270 and the contact electrode 280 transmit light to allow incident light from different angles to enter The photodiode 210; the insulating protective layer 290 covers the light-shielding metal layer 260 and the contact electrode 280, and the insulating protective layer 290 transmits light to allow incident light from different angles to enter the photodiode 210; The thin film transistor 230 is located in the first area of the substrate 20, and the first metal layer 240 is located in the second area of the substrate 20.
  • the light shielding metal layer 260 is used to prevent light from irradiating the thin film transistor 230.
  • the material of the connection electrode 270 and the contact electrode 280 may be a light-transmitting material such as indium tin oxide or zinc oxide.
  • the material of the substrate 20 may be a light-transmitting material, for example, the substrate 20 is a glass substrate.
  • FIG 8 and 9 show the optical path diagram of the photoelectric sensor 200 according to the embodiment of the present application.
  • incident light incident at different angles passes through the insulating protective layer 290, the contact electrode 280, and the connection electrode 270. After entering the photodiode 210, incident light incident at some angles passes through the photodiode 210 and reaches the reflection structure 220, and is reflected, and then returns to the photodiode 210.
  • the incident light incident at certain angles may undergo multiple reflections at the reflective structure 220, so that the photodiode 210 absorbs the incident light twice or even multiple times, thereby improving the light absorption rate and quantum efficiency.
  • the first metal layer 240 is arranged under the photodiode 210 as a reflective structure
  • FIG. 9 different angles of incidence
  • the incident light enters the photodiode 210 after passing through the insulating protection layer 290, the contact electrode 280, and the connection electrode 270.
  • the incident light incident at certain angles passes through the photodiode 210 and reaches the reflective structure 220 and When the first metal layer 240 is reflected, it returns to the photodiode 210 again.
  • the incident light incident at certain angles may undergo multiple reflections at the reflective structure 220 and the first metal layer 240, so that the photodiode 210 absorbs the incident light twice or even multiple times, thereby increasing the light absorption rate And quantum efficiency.
  • the photoelectric sensor provided by the embodiment of the application is provided with a reflective structure, which can make incident light incident at different angles be reflected when reaching the reflective structure through the photodiode, and return to the photodiode, which can improve the efficiency of the invisible near-infrared light source. Collect and improve photoelectric conversion efficiency.
  • the reflective structure can be arranged outside or inside the photodiode, or under the photodiode, and can also be arranged outside or inside the photodiode and under the photodiode at the same time, so that the photoelectric The diode area absorbs the reflected light twice or more times, thereby maximizing the light absorption rate.
  • the photoelectric sensor according to the embodiment of the present application is described above, and the preparation method of the photoelectric sensor according to the embodiment of the present application is described below.
  • the manufacturing method of the photoelectric sensor of the embodiment of the present application can prepare the photoelectric sensor of the foregoing embodiment of the present application, and the following embodiments and related descriptions in the foregoing embodiments can be referred to each other.
  • FIG. 10, FIG. 12, and FIG. 14 are schematic flowcharts of the manufacturing method of the photoelectric sensor according to the embodiment of the present application, but these steps or operations are only examples, and the embodiment of the present application may also perform other operations or FIG. Variations of each operation in FIG. 12 and FIG. 14.
  • FIG. 10 shows a schematic flowchart of a method 300 for manufacturing a photoelectric sensor according to an embodiment of the present application. As shown in FIG. 10, the manufacturing method 300 of the photoelectric sensor includes:
  • the first structure includes a thin film transistor, a photodiode, a first metal layer, a light-transmissive insulating layer, and a substrate, the thin film transistor is located in a first region of the substrate, and the The first metal layer is located in the second region of the substrate, the photodiode is located above the first metal layer, and the transparent insulating layer covers the thin film transistor and the photodiode.
  • the first structure is shown in FIG. 11a and can be obtained through a standard TFT photoelectric sensor manufacturing process.
  • the thin film transistor 230 includes a gate 231, a first insulating layer 232, a channel layer 233, a first conductive layer 234 and a second insulating layer 235.
  • the first insulating layer 232 covers the gate 231
  • the channel layer 233 is located on the first insulating layer 232
  • the first conductive layer 234 is located on the channel layer 233 and
  • the first conductive layer 234 has a gap exposing the channel layer 233 to separate the first conductive layer 234 into a source electrode and a drain electrode.
  • the layer 232 and the first conductive layer 234 extend below the photodiode 210, and the first conductive layer 234 serves as the lower electrode of the photodiode 210, and the second insulating layer 235 covers the channel Layer 233 and the first conductive layer 234 (except for the area in contact with the photodiode).
  • the thin film transistor 230 may not include the second insulating layer 235, that is, the transparent insulating layer 250 may directly cover the channel layer 233 and the first conductive layer 234.
  • the thin film transistor 230 is located in the first area of the substrate 20, the first metal layer 240 is located in the second area of the substrate 20, and the photodiode 210 is located in the first area.
  • the transparent insulating layer 250 covers the thin film transistor 230 and the photodiode 210.
  • DRIE Deep Reactive Ion Etch
  • a layer of photoresist is spin-coated on the upper surface (front side) of the light-transmitting insulating layer 250 in the first structure shown in FIG. 11a, and exposed and developed to form a photoresist not covered with photoresist. Eclipse graphics window.
  • a trench structure 30 is formed in the transparent insulating layer 250 by deep reactive ion etching. The trench structure 30 extends from the upper surface of the transparent insulating layer 250 down to the photodiode 210, as shown in FIG. 11b.
  • connection electrodes in the trench structure and prepare contact electrodes on the connection electrodes and the light-transmitting insulating layer to connect the photodiode with an external control circuit and/or power supply, and the connection
  • the electrode and the contact electrode transmit light to allow incident light incident at different angles to enter the photodiode.
  • a first light-transmitting conductive material is deposited in the trench structure 30 to form the connection electrode 270, as shown in FIG. 11c.
  • a second light-transmitting conductive material is deposited on the connection electrode 270 and the light-transmitting insulating layer 250 to form a second light-transmitting conductive layer, and covering the upper surface of the second light-transmitting conductive layer
  • a photosensitive dry film is exposed and developed to form a dry film protective layer covering the second transparent conductive layer.
  • dry etching is used to remove the second transparent conductive layer not covered with the photosensitive dry film, and finally the photosensitive The dry film forms the contact electrode 280, as shown in FIG. 11d.
  • the process of depositing the connection electrode 270 and/or the contact electrode 280 includes: atomic layer deposition (ALD), physical vapor deposition (Physical Vapor Deposition, PVD), organometallic chemical vapor deposition, Evaporation, electroplating, etc.
  • the first transparent conductive material may be zinc oxide or indium tin oxide
  • the second transparent conductive material may also be zinc oxide or indium tin oxide.
  • first light-transmitting conductive material and the second light-transmitting conductive material may be the same material, that is, the connecting electrode 270 and the contact electrode 280 may be one electrode.
  • a layer of photoresist is spin-coated on the upper surface (front side) of the light-transmitting insulating layer 250 in the structure shown in FIG. 11d, and exposed and developed to form an etching pattern that does not cover the photoresist. window.
  • a deep trench structure 40 is formed in the transparent insulating layer 250, and the deep trench structure 40 is located outside the photodiode 210.
  • the deep groove structure 40 extends downward from the upper surface of the transparent insulating layer 250, as shown in FIG. 11e.
  • a reflective material is deposited in the deep trench structure 40 to form the reflective structure 220, as shown in FIG. 11f.
  • air can be directly used as a reflective medium (reflective material), that is, no additional material is deposited in the deep groove structure 40.
  • the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite material.
  • the process for depositing the reflective structure 220 includes: ALD, PVD, metal organic chemical vapor deposition, evaporation, electroplating, and the like.
  • the reflective structure is prepared on the light-transmitting insulating layer along the height direction of the photodiode. That is, the deep trench structure 40 is etched along the height direction of the photodiode.
  • the thickness of the transparent insulating layer 250 located between the reflective structure 220 and the outer wall of the photodiode 210 is such that the photodiode 210 and the reflective structure 220 satisfy an optical resonance condition. That is, the thickness of the dielectric layer between the deep groove structure 40 and the outer wall of the photodiode 210 can be controlled by adjusting the photolithography and etching processes, so as to optimize the reflection system so that the photodiode 210 and the The optical resonance conditions are satisfied between the reflective structures 220.
  • the reflective structure 220 is continuously or discretely distributed around the photodiode 210. That is, through photolithography and etching processes, the deep trench structure 40 is etched in all or part of the dielectric layer area around the photodiode.
  • the pattern shape of the reflective structure 220 can be designed according to the specifications of the photoelectric sensor, and the description is not repeated here.
  • a light-shielding metal layer 260 is prepared on the transparent insulating layer 250 and the reflective structure 220 through deposition and photolithography processes, as shown in FIG. 11g.
  • step 304 and step 305 can be prepared together.
  • a transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode through deposition and photolithography processes, thereby preparing the photoelectric sensor as shown in FIG. 2 .
  • the reflective structure 220 is arranged on the outside of the photodiode 210, so that incident light from different angles can be reflected when it passes through the photodiode 210 and reaches the reflective structure 220, and returns to the photodiode 210.
  • the reflected light can be absorbed twice or more times, thereby improving the collection of the invisible near-infrared light source and improving the photoelectric conversion efficiency.
  • FIG. 12 shows a schematic flowchart of a method 400 for manufacturing a photoelectric sensor according to an embodiment of the present application. As shown in FIG. 12, the manufacturing method 400 of the photoelectric sensor includes:
  • the bottom gate 231 (the gate 231 of the thin film transistor 230) is prepared in the first area on the upper surface (front side) of the substrate 20, and the second area is prepared in the second area on the upper surface (front side) of the substrate 20.
  • a metal layer 240 as shown in Figure 13a.
  • the bottom gate 231 and the first metal layer 240 can be prepared simultaneously or separately.
  • the materials of the bottom gate 231 and the first metal layer 240 may be the same or different.
  • the material of the bottom gate 231 and/or the first metal layer 240 may be, for example, a metal, such as molybdenum, aluminum, or molybdenum aluminum alloy.
  • 401 is the standard structure and preparation process (for example, deposition and photolithography process) of a bottom-gate TFT device, which will not be repeated here.
  • a transparent first insulating layer 232 is prepared on the substrate 20, the bottom gate 231, and the first metal layer 240 through deposition and photolithography processes. , As shown in Figure 13b.
  • the material of the first insulating layer may be silicon nitride, silicon oxide, or other transparent dielectric layer materials, spin-on materials, and the like.
  • a channel layer 233 is prepared on the first insulating layer 232 through deposition and photolithography processes, and the channel layer 233 is located above the bottom gate 231 , As shown in Figure 13c.
  • the channel layer 233 may be a channel of the ⁇ -Si thin film.
  • the first conductive layer on the first insulating layer and the channel layer, where the first conductive layer includes a gap exposing the channel layer to separate the first conductive layer into
  • the first conductive layer extends above the first metal layer and exposes a portion of the first insulating layer above the first metal layer.
  • a first conductive layer 234 is prepared on the first insulating layer 232 and the channel layer 233 through deposition and photolithography processes, wherein the first conductive layer
  • the layer 234 includes a gap exposing the channel layer 233 to separate the first conductive layer 234 into a source electrode and a drain electrode, and the first conductive layer 234 (for example, a drain portion) extends to the first conductive layer 234.
  • the first conductive layer 234 for example, a drain portion
  • a second insulating layer 235 may also be prepared by deposition and photolithography processes, and the second insulating layer 235 covers the channel layer 233 and the The first conductive layer 234 exposes the first insulating layer 232 and the first conductive layer 234 above the first metal layer 240, as shown in FIG. 13e.
  • the material of the second insulating layer 235 may be silicon nitride or silicon oxide or a spin-on material.
  • the subsequent preparation of the photoelectric sensor may be performed on the structure shown in FIG. 13d, or the subsequent preparation of the photoelectric sensor may be performed on the structure shown in FIG. 13e.
  • the following is an example of the subsequent preparation of the photoelectric sensor on the structure shown in FIG. 13e.
  • a photodiode 210 is prepared on the first insulating layer 232 and the first conductive layer 234 located above the first metal layer 240, as shown in FIG. 13f .
  • the shape of the photodiode 210 may be regular, for example, it may be a cube, a cuboid, a cylinder, etc., of course, the shape of the photodiode 210 may also be irregular.
  • the photodiode 210 generally has a three-layer structure, which are respectively denoted from top to bottom as: P-type amorphous silicon film, intrinsic amorphous silicon film, N-type amorphous silicon film, and P-type amorphous silicon film as the photoelectric
  • P-type amorphous silicon film P-type amorphous silicon film
  • intrinsic amorphous silicon film N-type amorphous silicon film
  • P-type amorphous silicon film as the photoelectric
  • the anode of the diode 210, the N-type amorphous silicon film as the cathode of the photodiode 210, and the intrinsic amorphous silicon film as the light absorption layer of the photodiode 210.
  • 405 is the standard structure of the photodiode and the preparation process (for example, deposition and photolithography process), which will not be repeated here.
  • a transparent insulating layer 250 is prepared on the first insulating layer 232, the first conductive layer 234, and the photodiode 210 through deposition and photolithography processes, As shown in Figure 13g.
  • a layer of photoresist is spin-coated on the upper surface (front side) of the light-transmitting insulating layer 250, and exposed and developed to form an etching pattern that does not cover the photoresist window.
  • a trench structure 30 is formed in the transparent insulating layer 250 by deep reactive ion etching. The trench structure 30 extends from the upper surface of the transparent insulating layer 250 down to the photodiode 210, as shown in FIG. 13h.
  • connection electrodes in the trench structure and prepare contact electrodes on the connection electrodes and the light-transmitting insulating layer to connect the photodiode with an external control circuit and/or power supply, and the connection
  • the electrode and the contact electrode transmit light to allow incident light incident at different angles to enter the photodiode.
  • a first transparent conductive material is deposited in the trench structure 30 to form the connection electrode, as shown in FIG. 13i.
  • a second light-transmitting conductive material is deposited on the connection electrode 270 and the light-transmitting insulating layer 250 to form a second light-transmitting conductive layer, and covering the upper surface of the second light-transmitting conductive layer
  • a photosensitive dry film is exposed and developed to form a dry film protective layer covering the second light-transmitting conductive layer.
  • dry etching is used to remove the second light-transmitting conductive layer not covering the photosensitive dry film, and finally the photosensitive Dry film to form the contact electrode 280, as shown in FIG. 13j.
  • the process of depositing the connecting electrode 270 and/or the contact electrode 280 includes: ALD, PVD, organic metal chemical vapor deposition, evaporation, electroplating, and the like.
  • the first transparent conductive material may be zinc oxide or indium tin oxide
  • the second transparent conductive material may also be zinc oxide or indium tin oxide.
  • first light-transmitting conductive material and the second light-transmitting conductive material may be the same material, that is, the connecting electrode 270 and the contact electrode 280 may be one electrode.
  • a light-shielding metal layer 260 is prepared on the transparent insulating layer 250 through deposition and photolithography processes, as shown in FIG. 13k.
  • a transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode, and the photoelectric device as shown in FIG. 7 is prepared. sensor.
  • incident light incident at certain angles passes through the photodiode 210 and reaches the reflective structure 220 and the first metal layer 240 and is reflected, and then returns to the photodiode 210.
  • the incident light incident at certain angles may undergo multiple reflections at the reflective structure 220 and the first metal layer 240, so that the photodiode 210 absorbs the incident light twice or even multiple times, thereby increasing the light absorption rate And quantum efficiency.
  • the thickness of the first insulating layer 232 located between the first metal layer 240 and the lower surface of the photodiode 210 is such that the distance between the photodiode 210 and the first metal layer 240 satisfies Optical resonance conditions.
  • the absorption ratio of monochromatic light with a wavelength of 940 nm in silicon (photodiode) varies with the silicon dioxide dielectric layer (the second light-transmitting medium layer)
  • the curve of thickness d change is shown in Figure 3.
  • the reflective structure (the first metal layer 240) is disposed under the photodiode 210, so that incident light from different angles can be passed through the photodiode 210 and reach the first metal layer 240. Reflect and return to the photodiode 210.
  • the area of the photodiode 210 can absorb the reflected light twice or more times, thereby improving the collection of the invisible near-infrared light source and improving the photoelectric conversion efficiency.
  • the method 400 further includes:
  • a reflective structure located outside the photodiode is prepared on the light-transmitting insulating layer, so that the incident light is reflected when it passes through the photodiode and reaches the reflective structure, and returns to the photodiode again.
  • a layer of photoresist is spin-coated on the upper surface (front side) of the light-transmitting insulating layer 250 in the structure shown in FIG. 13j, and exposed and developed to form an etching pattern that does not cover the photoresist. window.
  • a deep trench structure 40 is formed in the transparent insulating layer 250, and the deep trench structure 40 is located outside the photodiode 210.
  • the deep groove structure 40 extends downward from the upper surface of the transparent insulating layer 250, as shown in FIG. 13l.
  • a reflective material is deposited in the deep trench structure 40 to form the reflective structure 220, as shown in FIG. 13m.
  • the light-shielding metal layer 260 may be prepared on the transparent insulating layer 250 and the reflective structure 220 in the structure shown in FIG. 13m, as shown in FIG. 13n.
  • a transparent insulating protective layer 290 may be prepared on the light-shielding metal layer 260 and the contact electrode 280 in the structure shown in FIG. 13n, thereby preparing the photoelectric sensor as shown in FIG. 5.
  • air can be directly used as a reflective medium (reflective material), that is, no additional material is deposited in the deep groove structure 40.
  • the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite material.
  • the process for depositing the reflective structure 220 includes: ALD, PVD, metal organic chemical vapor deposition, evaporation, electroplating, and the like.
  • the reflective structure is prepared on the light-transmitting insulating layer along the height direction of the photodiode. That is, the deep trench structure 40 is etched along the height direction of the photodiode.
  • the thickness of the transparent insulating layer 250 located between the reflective structure 220 and the outer wall of the photodiode 210 is such that the photodiode 210 and the reflective structure 220 satisfy an optical resonance condition. That is, the thickness of the dielectric layer between the deep groove structure 40 and the outer wall of the photodiode 210 can be controlled by adjusting the photolithography and etching processes, so as to optimize the reflection system so that the photodiode 210 and the The optical resonance conditions are satisfied between the reflective structures 220.
  • the reflective structure 220 is continuously or discretely distributed around the photodiode 210. That is, through photolithography and etching processes, the deep trench structure 40 is etched in all or part of the dielectric layer area around the photodiode.
  • the pattern shape of the reflective structure 220 can be designed according to the specifications of the photoelectric sensor, and the description is not repeated here.
  • the reflective structure 220 is arranged outside the photodiode 210, and the reflective structure (the first metal layer 240) is arranged under the photodiode 210, so that incident light from different angles can be After the photodiode 210 reaches the reflective structure 220 and the first metal layer 240, it is reflected and returns to the photodiode 210. The reflected light can be absorbed twice or more by the photodiode 210 area, thereby increasing the invisible proximity of people. Collection of infrared light source and improvement of photoelectric conversion efficiency.
  • the method 400 further includes:
  • a layer of photoresist is spin-coated on the upper surface (front side) of the photodiode 210 in the structure shown in FIG. 13f, and exposed and developed to form an etching pattern window that is not covered with the photoresist.
  • a deep groove structure 40 is formed in the photodiode 210 by deep reactive ion etching, and the deep groove structure 40 is located in an area close to the outer wall of the photodiode 210.
  • the deep groove structure 40 extends downward from the upper surface of the photodiode 210, as shown in FIG. 13o.
  • a reflective material is deposited in the deep trench structure 40 to form the reflective structure 220, as shown in FIG. 13p.
  • the first insulating layer 232, the first conductive layer 234, the photodiode 210 and the A transparent insulating layer 250 is formed on the reflective structure 220, as shown in FIG. 13q.
  • the photoelectric sensor as shown in FIG. 6 is prepared.
  • air can be directly used as a reflective medium (reflective material), that is, no additional material is deposited in the deep groove structure 40.
  • the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite material.
  • the process for depositing the reflective structure 220 includes: ALD, PVD, metal organic chemical vapor deposition, evaporation, electroplating, and the like.
  • the reflective structure is prepared in the photodiode along the height direction of the photodiode. That is, the deep trench structure 40 is etched along the height direction of the photodiode.
  • the reflective structure 220 is continuously or discretely distributed in a region close to the outer wall of the photodiode 210. That is, through photolithography and etching processes, the deep groove structure 40 is continuously or discretely etched in the photodiode near the outer wall of the photodiode 210.
  • the pattern shape of the reflective structure 220 can be designed according to the specifications of the photoelectric sensor, and the description is not repeated here.
  • the reflective structure 220 is provided inside the photodiode 210, and the reflective structure (the first metal layer 240) is provided below the photodiode 210, so that incident light from different angles can be After the photodiode 210 reaches the reflective structure 220 and the first metal layer 240, it is reflected and returns to the photodiode 210. The reflected light can be absorbed twice or more by the photodiode 210 area, thereby increasing the invisible proximity of people. Collection of infrared light source and improvement of photoelectric conversion efficiency.
  • FIG. 14 shows a schematic flowchart of a method 500 for preparing a photoelectric sensor according to an embodiment of the present application.
  • the manufacturing method 500 of the photoelectric sensor includes:
  • the reflective structure is prepared on the photodiode near the outer wall along the height direction of the photodiode.
  • the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.
  • the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.
  • connection electrodes in the trench structure and prepare contact electrodes on the connection electrodes and the light-transmitting insulating layer to connect the photodiode with an external control circuit and/or power supply, and the connection
  • the electrode and the contact electrode transmit light to allow incident light incident at different angles to enter the photodiode.
  • the photoelectric sensor manufacturing method 500 can manufacture the photoelectric sensor as shown in FIG. 4.
  • the reflective structure 220 is disposed inside the photodiode 210, so that incident light incident at different angles can be reflected when passing through the photodiode 210 to the reflective structure 220, and return to the photodiode 210.
  • the reflected light can be absorbed twice or more times, thereby improving the collection of the invisible near-infrared light source and improving the photoelectric conversion efficiency.
  • the steps in the manufacturing method 500 of the photoelectric sensor may refer to the corresponding steps in the manufacturing method 300 of the photoelectric sensor and the manufacturing method 400 of the photoelectric sensor.

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Abstract

本申请提供一种光电传感器及其制备方法，能够提高人不可见的近红外光源的采集以及提高光电转换效率。所述光电传感器包括：光电二极管和反射结构，其中，所述反射结构设置于所述光电二极管的外侧或者内部，和/或，所述反射结构设置于所述光电二极管的下方，以使不同角度入射的入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中。

Description

光电传感器及其制备方法 技术领域
本申请涉及光电传感器领域，并且更具体地，涉及一种光电传感器及其制备方法。
背景技术
光电传感器是一种基于光电效应将光信号转换为电信号的器件，其中，薄膜晶体管光电传感器是一种典型的光电传感器，一般是由控制电信号传输的薄膜晶体管(Thin Film Transistor，TFT)和用于将光信号转换为电信号的光电二极管(Photodiode，PD)等组成。
近年来，随着医学成像，指纹图像采集，以及指纹识别市场的发展，薄膜晶体管光电传感器得到了广泛的应用。然而，由于近红外光的波长(780～2526nm)比可见光(380～780nm)的波长要长，在薄膜晶体管光电传感器的光电二极管结构中，近红外光的吸收率较低，同时由于红外波长容易透过薄膜晶体管光电传感器的光电二极管结构，进一步造成吸收效率降低。因此，如何提高对人眼不可见的近红外(Near Infrared，NIR)光源的采集以及提高光电转换效率成为薄膜晶体管光电传感器领域亟待解决的问题之一。
发明内容
本申请提供一种光电传感器及其制备方法，能够提高人不可见的近红外光源的采集以及提高光电转换效率。
第一方面，提供了一种光电传感器，包括：光电二极管和反射结构，
其中，所述反射结构设置于所述光电二极管的外侧或者内部，和/或，所述反射结构设置于所述光电二极管的下方，以使不同角度入射的入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中。
本申请实施例提供的光电传感器中设置有反射结构，可以使不同角度入射的入射光在经过光电二极管到达反射结构时被反射，重新回到光电二极管中，能够提高人不可见的近红外光源的采集以及提高光电转换效率。
进一步地，在本申请实施例中，反射结构可以设置于光电二极管的外侧或者内部，也可以设置于光电二极管的下方，还可以同时设置于光电二极管的外侧或者内部以及光电二极管的下方，使得光电二极管区域对反射光进行二次甚至更多次吸收，从而最大程度提高光吸收率。
在一些可能的实现方式中，所述反射结构沿所述光电二极管的高度方向设置于所述光电二极管的外侧或者内部。
在一些可能的实现方式中，若所述反射结构设置于所述光电二极管的外侧，在所述反射结构与所述光电二极管的外壁之间设置有第一透光介质层，且所述第一透光介质层的厚度使得所述光电二极管与所述反射结构之间满足针对所述入射光的光学谐振条件。
应理解，在所述光电二极管与所述反射结构之间满足针对所述入射光的光学谐振条件时，所述光电二极管对所述入射光的吸收比率达到最大值。
在一些可能的实现方式中，所述反射结构围绕所述光电二极管连续或者离散分布。
假设所述光电二极管为正方体，四个侧面分别记为a,b,c,d，两个底面分别记为e,f。例如，所述反射结构围绕所述光电二极管，连续分布于a,b,c,d四个侧面的外侧。又例如，所述反射结构围绕所述光电二极管，离散分布于a,c两个侧面的外侧。再例如，所述反射结构围绕所述光电二极管，离散分布于侧面a的外侧。即所述反射结构离散分布时，其离散位置可以是随机产生的，也可以是基于特定规律产生的，本申请实施例对此不作限定。
在一些可能的实现方式中，若所述反射结构设置于所述光电二极管的内部，所述反射结构位于靠近所述光电二极管的外壁的区域。
需要说明的是，所述反射结构位于靠近所述光电二极管的外壁的区域，可以最大限度上减小对所述光电二极管性能的影响。
在一些可能的实现方式中，所述反射结构在靠近所述光电二极管的外壁的区域连续或者离散分布。
假设所述光电二极管为正方体，四个侧面分别记为a,b,c,d，两个底面分别记为e,f。例如，所述反射结构在靠近所述光电二极管的a,b,c,d四个侧面的区域连续分布。又例如，所述反射结构在靠近所述光电二极管的b,d两个侧面的区域离散分布。再例如，所述反射结构在靠近所述光电二极管的侧面a的区域离散分布。即所述反射结构离散分布时，其离散位置可以是随机产 生的，也可以是基于特定规律产生的，本申请实施例对此不作限定。
在一些可能的实现方式中，所述反射结构沿所述光电二极管的水平方向设置于所述光电二极管的下方。
需要说明的是，所述光电二极管的水平方向可以是垂直于所述光电二极管的高度方向的方向。
在一些可能的实现方式中，若所述反射结构设置于所述光电二极管的下方，在所述反射结构与所述光电二极管的下表面之间设置有第二透光介质层，且所述第二透光介质层的厚度使得所述光电二极管与所述反射结构之间满足针对所述入射光的光学谐振条件。
应理解，在所述光电二极管与所述反射结构之间满足针对所述入射光的光学谐振条件时，所述光电二极管对所述反射光的吸收比率达到最大值。
在一些可能的实现方式中，所述反射结构还用于阻挡光从所述光电二极管的下方进入所述光电二极管。
在一些可能的实现方式中，所述光电二极管的下电极位于所述光电二极管与所述反射结构之间，且所述光电二极管的下电极位于所述光电二极管的***区域下方，以允许所述入射光在经过所述光电二极管之后到达所述反射结构。
应理解，所述光电二极管的下电极为非透明材质，在所述光电二极管的下电极位于所述光电二极管的***区域下方时，不影响所述入射光在经过所述光电二极管之后到达所述反射结构。
在一些可能的实现方式中，所述光电传感器还包括薄膜晶体管，所述薄膜晶体管与所述光电二极管构成所述光电传感器的像素单元。
可选地，在本申请实施例中，所述光电传感器可以包括至少一个像素单元，每个像素单元包括一个薄膜晶体管和一个光电二极管。
在一些可能的实现方式中，所述薄膜晶体管包括：
栅极，
覆盖于所述栅极上的由透光绝缘材料形成的第一绝缘层，
位于所述第一绝缘层上的沟道层，
位于所述沟道层和所述第一绝缘层上的第一导电层，所述第一导电层上具有露出所述沟道层的空隙，以将所述第一导电层分隔为源极和漏极，
其中，所述第一绝缘层延伸至所述光电二极管的下方，且位于所述反射 结构上方的部分形成所述第二透光介质层；所述第一导电层延伸至所述光电二极管的***区域下方，以形成所述光电二极管的下电极。
在一些可能的实现方式中，所述反射结构、所述第一绝缘层和所述第一导电层形成存储电容，以增加所述光电二极管探测的动态范围。
在一些可能的实现方式中，若所述反射结构设置于所述光电二极管的外侧或者内部，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
需要说明的是，若所述反射结构的反射材料为空气，则所述反射结构可以是一沟槽结构，且这一沟槽结构内未填充除空气之外的其他材料。
在一些可能的实现方式中，若所述反射结构设置于所述光电二极管的下方，所述反射结构的反射材料为金属。
在一些可能的实现方式中，所述入射光为近红外光。
第二方面，提供了一种光电传感器的制备方法，包括：
制备第一结构，其中，所述第一结构包括薄膜晶体管、光电二极管、第一金属层、透光绝缘层和衬底，所述薄膜晶体管位于所述衬底的第一区域，所述第一金属层位于所述衬底的第二区域，所述光电二极管位于所述第一金属层的上方，所述透光绝缘层覆盖所述薄膜晶体管和所述光电二极管；
在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管；
在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光电二极管；
在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
在所述透光绝缘层和所述反射结构上方制备遮光金属层；
在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
在一些可能的实现方式中，所述在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，包括：
在所述透光绝缘层上沿所述光电二极管的高度方向制备所述反射结构。
在一些可能的实现方式中，位于所述反射结构与所述光电二极管的外壁 之间的所述透光绝缘层的厚度使得所述光电二极管与所述反射结构之间满足光学谐振条件。
在一些可能的实现方式中，所述反射结构围绕所述光电二极管连续或者离散分布。
在一些可能的实现方式中，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
第三方面，提供了一种光电传感器的制备方法，包括：
在衬底表面的第一区域制备底栅，以及在所述衬底表面的第二区域制备第一金属层；
在所述衬底、所述底栅和所述第一金属层上制备透光的第一绝缘层；
在所述第一绝缘层上制备沟道层，所述沟道层位于所述底栅的上方；
在所述第一绝缘层和所述沟道层上制备第一导电层，其中，所述第一导电层包括露出所述沟道层的空隙，以将所述第一导电层分隔为源极和漏极，所述第一导电层延伸至所述第一金属层的上方，且露出部分位于所述第一金属层上方的所述第一绝缘层；
在位于所述第一金属层上方的所述第一绝缘层和所述第一导电层上制备光电二极管；
在所述第一绝缘层、所述第一导电层和所述光电二极管上制备透光绝缘层；
在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管；
在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光电二极管；
在所述透光绝缘层上方制备遮光金属层；
在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
在一些可能的实现方式中，位于所述第一金属层与所述光电二极管的下表面之间的所述第一绝缘层的厚度使得所述光电二极管与所述第一金属层之间满足光学谐振条件。
在一些可能的实现方式中，在制备所述遮光金属层之前，所述方法还包括：
在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
所述在所述透光绝缘层上方制备遮光金属层，包括：
在所述透光绝缘层和所述反射结构上方制备所述遮光金属层。
在一些可能的实现方式中，所述在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，包括：
在所述透光绝缘层上沿所述光电二极管的高度方向制备所述反射结构。
在一些可能的实现方式中，位于所述反射结构与所述光电二极管的外壁之间的所述透光绝缘层的厚度使得所述光电二极管与所述反射结构之间满足光学谐振条件。
在一些可能的实现方式中，所述反射结构围绕所述光电二极管连续或者离散分布。
在一些可能的实现方式中，在制备所述透光绝缘层之前，所述方法还包括：
在所述光电二极管上制备反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
所述在所述第一绝缘层、所述第一导电层和所述光电二极管上制备透光绝缘层，包括：
在所述第一绝缘层、所述第一导电层、所述反射结构和所述光电二极管上制备透光绝缘层。
在一些可能的实现方式中，所述在所述光电二极管上制备反射结构，包括：
在所述光电二极管上靠近外壁的区域沿所述光电二极管的高度方向制备所述反射结构。
在一些可能的实现方式中，所述反射结构在靠近所述光电二极管的外壁的区域连续或者离散分布。
在一些可能的实现方式中，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
第四方面，提供了一种光电传感器的制备方法，包括：
在衬底表面的第一区域制备底栅，以及在所述衬底表面的第二区域制备 第一金属层；
在所述衬底、所述底栅和所述第一金属层上制备透光的第一绝缘层；
在所述第一绝缘层上制备沟道层，所述沟道层位于所述底栅的上方；
在所述第一绝缘层和所述沟道层上制备第一导电层，其中，所述第一导电层包括露出所述沟道层的空隙，以将所述第一导电层分隔为源极和漏极，所述第一导电层延伸至所述第一金属层的上方；
在位于所述第一金属层上方的所述第一导电层上制备光电二极管；
在所述光电二极管上制备反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
在所述第一绝缘层、所述第一导电层、所述反射结构和所述光电二极管上制备透光绝缘层；
在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管；
在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光电二极管；
在所述透光绝缘层上方制备遮光金属层；
在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
在一些可能的实现方式中，所述在所述光电二极管上制备反射结构，包括：
在所述光电二极管上靠近外壁的区域沿所述光电二极管的高度方向制备所述反射结构。
在一些可能的实现方式中，所述反射结构在靠近所述光电二极管的外壁的区域连续或者离散分布。
在一些可能的实现方式中，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
第五方面，提供了一种电子设备，包括如第一方面以及第一方面任一可能的实现方式所述的光电传感器。
附图说明
图1是本申请实施例所适用的终端设备的结构示意图。
图2是根据本申请实施例的一种光电传感器的示意性结构图。
图3是光电二极管对入射光的吸收比例随反射结构与光电二极管之间的介质层的厚度变化的示意图。
图4是根据本申请实施例的又一种光电传感器的示意性结构图。
图5是根据本申请实施例的再一种光电传感器的示意性结构图。
图6是根据本申请实施例的再一种光电传感器的示意性结构图。
图7是根据本申请实施例的再一种光电传感器的示意性结构图。
图8是根据本申请实施例的光线射入光电二极管后的反射光路示意图。
图9是根据本申请实施例的光线射入光电二极管后的反射光路示意图。
图10是根据本申请实施例的一种光电传感器的制备方法的示意性流程图。
图11a至图11g是制备本申请一种实施例的光电传感器的示意图。
图12是根据本申请实施例的又一种光电传感器的制备方法的示意性流程图。
图13a至图13q是制备本申请又一种实施例的光电传感器的示意图。
图14是根据本申请实施例的再一种光电传感器的制备方法的示意性流程图。
具体实施方式
下面将结合附图，对本申请实施例中的技术方案进行描述。
应理解，本申请实施例可以应用于光电传感器领域，例如，薄膜晶体管光电传感器领域，包括但不限于光学指纹识别***、基于光学指纹成像的医疗诊断产品、指纹图像录入和平板扫描设备，本申请实施例仅以光学指纹***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电传感器的***等。
还应理解，在本申请实施例中，光电传感器中薄膜晶体管的具体结构包括但不限于底栅型薄膜晶体管和顶栅型薄膜晶体管，薄膜晶体管的具体材料包括但不限于非晶硅薄膜晶体管、低温多晶硅(Low Temperature Poly-silicon，LTPS)薄膜晶体管，原则上只要利用光电薄膜工艺制造的包括薄膜晶体管(TFT)开关以及光电二极管(PD)的光电传感器均在本申请讨论范围内。本申请实施例仅以底栅型薄膜晶体管为例进行说明，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薄膜晶体管的光电传感器。
作为一种常见的应用场景，本申请实施例提供的光学指纹***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终端设备；更具体地，在上述终端设备中，指纹识别装置可以具体为光学指纹装置，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)光学指纹***。或者，所述指纹识别装置也可以部分或者全部集成至所述终端设备的显示屏内部，从而形成屏内(In-display)光学指纹***。
如图1所示为本申请实施例可以适用的终端设备的结构示意图，所述终端设备10包括显示屏120和光学指纹装置130，其中，所述光学指纹装置130设置在所述显示屏120下方的局部区域。所述光学指纹装置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，所述感应阵列所在区域或者其感应区域为所述光学指纹装置130的指纹检测区域103。如图1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，所述光学指纹装置130还可以设置在其他位置，比如所述显示屏120的侧面或者所述终端设备10的边缘非透光区域，并通过光路设计来将所述显示屏120的至少部分显示区域的光信号导引到所述光学指纹装置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。
应当理解，所述指纹检测区域103的面积可以与所述光学指纹装置130的感应阵列的面积不同，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装置130的指纹检测区域103的面积大于所述光学指纹装置130感应阵列的面积。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，所述光学指纹装置130的指纹检测区域103也可以设计成与所述光学指纹装置130的感应阵列的面积基本一致。
因此，使用者在需要对所述终端设备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终端设备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终端设备10的正面。
作为一种可选的实现方式，如图1所示，所述光学指纹装置130包括光检测部分134和光学组件132，所述光检测部分134包括所述感应阵列以及与所述感应阵列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)，比如光学成像芯片或者光学指纹传感器，所述感应阵列具体为光探测器(Photo detector)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所在的芯片外部，比如将所述光学组件132贴合在所述芯片上方，或者将所述光学组件132的部分元件集成在上述芯片之中。
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，从而所述感应阵列便可以检测出手指的指纹图像。
在另一种实施例中，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，以使得所述感应阵列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 装置的视场，以提高所述光学指纹装置130的指纹成像效果。
在其他实施例中，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的感应阵列上方，并且每一个微透镜可以分别对应于所述感应阵列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，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。应当理解，上述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。
作为一种可选的实施例，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，所述光学指纹装置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)来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。由于指纹的嵴(ridge)与峪(vally)对于光的反射能力不同，因此，来自指纹嵴的反射光151和来自指纹峪的发生过152具有不同的光强，反射光经过光学组件132后，被光学指纹装置130中的感应阵列134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，从而在所述终端设备10实现光学指纹识别功能。
在其他实施例中，所述光学指纹装置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，所述光学指纹装置 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，所述终端设备10的光学指纹***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终端设备10的保护盖板下方的边缘区域，而所述光学指纹装置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装置130；或者，所述光学指纹装置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装置130。当采用所述光学指纹装置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。
应当理解的是，在具体实现上，所述终端设备10还包括透明保护盖板，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的上方并覆盖所述终端设备10的正面。因为，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，在某些实施例中，所述光学指纹装置130可以仅包括一个光学指纹传感器，此时光学指纹装置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，否则光学指纹装置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，所述光学指纹装置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装置130的指纹检测区域103。也即是说，所述光学指纹装置130的指纹检测区域103可以包括多个子区域，每个子区域分别对应于其中一个光学指纹传感器的感应区域，从而将所述光学指纹模组130的指纹采集区域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。可替代地，当所述光学指纹传感器数量足够时，所述指纹检测区域130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。
需要说明的是，本申请实施例以薄膜晶体管光电传感器为例进行详细的阐述。具体地，在本申请实施例中，由于近红外光的波长(780～2526nm)比可见光(380～780nm)的波长要长，在薄膜晶体管光电传感器的光电二极管结构中，近红外光的吸收率较低，同时由于红外波长容易透过薄膜晶体管光电传感器的光电二极管结构，进一步造成吸收效率降低。基于上述问题，本申请在光电传感器中设置了反射结构，通过控制光电二极管与反射结构之间介质层的厚度，形成针对特定波长的入射光最优化的光学谐振腔结构，使得如红外光等不同波长光的利用率最大化，从而提高对人眼不可见的近红外(NIR)光源的采集以及提高光电转换效率。
图2示出了本申请一个实施例的光电传感器200的示意图。
光电传感器200可以是基于薄膜晶体管的光电传感器，图2为其截面图。
如图2所示，光电传感器200可以包括：光电二极管210和反射结构220。
所述反射结构220设置于所述光电二极管210的外侧，以使不同角度入射的入射光在经过所述光电二极管210到达所述反射结构220时被反射，重新回到所述光电二极管210中。
可选地，所述入射光可以是可见光和/或红外光，例如，可以是近红外光。
在本申请实施例中，所述光电二极管210的形状可以是规则的，例如，可以是正方体、长方体、圆柱体等，当然，所述光电二极管210的形状也可以是不规则的。所述光电二极管210一般为三层结构，从上到下分别记为：P型无定型硅薄膜、本征无定型硅薄膜、N型无定型硅薄膜，P型无定型硅薄膜作为所述光电二极管210的阳极，N型无定型硅薄膜作为所述光电二极管210的阴极，本征无定型硅薄膜作为所述光电二极管210的光吸收层。
可选地，所述反射结构220围绕所述光电二极管210连续或者离散分布。
假设所述光电二极管210为正方体，四个侧面分别记为a,b,c,d，两个底面分别记为e,f。例如，所述反射结构220围绕所述光电二极管210，连续分布于a,b,c,d四个侧面的外侧。又例如，所述反射结构220围绕所述光电二极管210，离散分布于a,c两个侧面的外侧。再例如，所述反射结构220围绕所述光电二极管210，离散分布于侧面a的外侧。即所述反射结构220离散分布时，其离散位置可以是随机产生的，也可以是基于特定规律产生的，本申请实施例对此不作限定。
在本申请实施例中，所述反射结构220的形状和尺寸可以根据实际需要进行设置，例如可以是具有较大深宽比的柱状或者墙状结构，又例如，可以是具有较大深宽比的沟槽状结构。
可选地，如图2所示，所述反射结构220沿所述光电二极管210的高度方向设置于所述光电二极管210的外侧。
需要说明的是，所述反射结构220与周围介质具有较大的折射率差值，并可在所述反射结构220与周围介质所形成的界面区域具有较高的反射率。
可选地，所述反射结构220的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
需要说明的是，若所述反射结构220的反射材料为空气，则所述反射结构220可以是一沟槽结构，且这一沟槽结构内未填充除空气之外的其他材料。
可选地，在所述反射结构220与所述光电二极管210的外壁之间设置有第一透光介质层，且所述第一透光介质层的厚度使得所述光电二极管210与所述反射结构220之间满足针对所述入射光的光学谐振条件。
应理解，在所述光电二极管210与所述反射结构220之间满足针对入射光的光学谐振条件时，所述光电二极管210对入射光的吸收率达到最大值。
需要说明的是，当一束垂直入射单一波长的入射光在入射进入光电二极管时，在空气与光电二极管界面，光电二极管与介质层界面，以及介质层与反射结构界面分别会发生反射，产生反射光。
形成光学谐振的条件为：介质层(光电二极管与介质层界面)上的反射光与反射结构(介质层与反射结构界面)上的反射光的相位差为零或是2π的整数倍，即形成驻波。
当介质层的厚度d发生改变时会导致上述相位改变θ，如公式1所示，
Figure PCTCN2019072864-appb-000001
其中，d为介质层的厚度，λ为单色光的波长。
反射结构对光的吸收会引起相位改变
Figure PCTCN2019072864-appb-000002
如公式2所示，
Figure PCTCN2019072864-appb-000003
其中，n d为介质层的折射率，n r为反射结构的折射率，k r为反射结构的消光系数。
形成驻波的条件如公式3所示，
Figure PCTCN2019072864-appb-000004
由公式1～3可知，在反射结构材料确定的情况下，只需介质层厚度满足特定要求，即可得到针对特定波长的入射光形成驻波的条件。
也就是说，在本申请实施例中，在所述反射结构220的材料确定的情况下，通过控制所述第一透光介质层的厚度d1满足一定条件，使得所述光电二极管210与所述反射结构220之间满足针对所述入射光的光学谐振条件。
例如，在反射结构220的材料确定的情况下，940纳米波长的单色光在硅(光电二极管)中的吸收比例随二氧化硅介质层的厚度d1变化的曲线如图3所示。根据公式3可以计算出，当d1＝144.9nm、468.8nm和792.6nm时，均可使所述光电二极管210与所述反射结构220之间满足光学谐振条件，此时光电二极管对这一单色光(940纳米波长)的吸收比例达到极大值，为38.5％。另外，可以看到若没有二氧化硅介质层，所述光电二极管210对这一单色光(940纳米波长)的吸收比例只有5％。
可选地，在本申请一个实施例中，所述光电传感器200还包括薄膜晶体管230，所述薄膜晶体管230与所述光电二极管210构成所述光电传感器200的像素单元。
可选地，所述光电传感器200可以包括至少一个像素单元，每个像素单元包括一个薄膜晶体管和一个光电二极管。
可选地，如图2所示，所述薄膜晶体管230包括：
栅极231，第一绝缘层232，沟道层233，第一导电层234。
其中，所述第一绝缘层232覆盖于所述栅极231上，所述沟道层233位于所述第一绝缘层232上，所述第一导电层234位于所述沟道层233和所述第一绝缘层232上，所述第一导电层234上具有露出所述沟道层233的空隙，以将所述第一导电层234分隔为源极和漏极，所述第一绝缘层232和所述第一导电层234延伸至所述光电二极管210的下方，且所述第一导电层234作为所述光电二极管210的下电极。
需要说明的是，在本实施例中，所述栅极231的材料可以为金属，例如，钼、铝或者钼铝合金等。
所述第一绝缘层232的材料可以是具有透光特性的氮化硅，也可以是氧化硅，还可以是其他的透明介质材料或旋涂材料，例如，二氧化硅。所述沟道层233可以是α-Si薄膜的沟道(channel)。
可选地，如图2所示，所述薄膜晶体管230还包括：第二绝缘层235，其中，所述第二绝缘层235覆盖所述沟道层233和所述第一导电层234(除与所述光电二极管接触的区域)。
所述第二绝缘层235的材料可以是氮化硅或氧化硅或旋涂材料。
可选地，如图2所示，所述光电传感器200还包括第一金属层240，所述第一金属层240设置于所述光电二极管210的下方，用于阻挡光从所述光电二极管210的下方进入所述光电二极管210。同时，所述第一绝缘层232延伸至所述光电二极管210的下方并覆盖所述第一金属层240。
可选地，如图2所示，所述光电传感器200还包括透光金属层250，其中，所述透光金属层250覆盖所述薄膜晶体管230和所述光电二极管210的部分区域。
如图2所示，所述反射结构220设置于所述透光金属层250中，即位于所述反射结构220与所述光电二极管210的外壁之间的所述透光绝缘层250即为所述第一透光介质层，可以通过调节位于所述反射结构220与所述光电二极管210的外壁之间的所述透光绝缘层250的厚度使得所述光电二极管与所述反射结构之间满足光学谐振条件。
可选地，在本申请一个实施例中，如图4所示，所述反射结构220设置于所述光电二极管210的内部，以使不同角度入射的入射光在经过所述光电二极管210到达所述反射结构220时被反射，重新回到所述光电二极管210中。
在前述图2所述的实施例中，所述反射结构220设置于所述光电二极管210的外侧。在本实施例中，如图4所示，所述反射结构220设置于所述光电二极管210的内部。例如，所述反射结构220位于靠近所述光电二极管210的外壁的区域。可选地，所述反射结构220沿所述光电二极管210的高度方向设置于所述光电二极管210的内部。由于构成所述光电二极管210的非晶硅材料与空气或二氧化硅有较大的折射率差别，当光照射在所述光电二极管210与所述反射结构220界面上会产生很好的反射效果，提高光的反射率。
可选地，如图4所示，所述反射结构220在靠近所述光电二极管210的外壁的区域连续或者离散分布。
假设所述光电二极管210为正方体，四个侧面分别记为a,b,c,d，两个底面分别记为e,f。例如，所述反射结构220在靠近所述光电二极管210的a,b,c,d 四个侧面的区域连续分布。又例如，所述反射结构220在靠近所述光电二极管210的b,d两个侧面的区域离散分布。再例如，所述反射结构220在靠近所述光电二极管210的侧面a的区域离散分布。即所述反射结构220离散分布时，其离散位置可以是随机产生的，也可以是基于特定规律产生的，本申请实施例对此不作限定。
应理解，除了反射结构220的位置设置不同外，图4和图2的其他设置相同，为了简洁，不再赘述。
可选地，在本申请一个实施例中，如图5所示，图2所示的实施例中的所述第一金属层240也作为一个反射结构，即所述反射结构220(所述第一金属层240)还设置于所述光电二极管210的下方。所述第一金属层240使不同角度入射的入射光在经过所述光电二极管210到达所述第一金属层240时被反射，重新回到所述光电二极管210中。
在前述图2所述的实施例中，所述第一绝缘层232和所述第一导电层234延伸至所述光电二极管210的下方，且所述第一导电层234作为所述光电二极管210的下电极。在本实施例中，如图5所示，所述第一绝缘层232由透光绝缘材料形成，且所述第一绝缘层232延伸至所述光电二极管210的下方，并覆盖所述第一金属层240；所述第一导电层234延伸至所述光电二极管210的***区域下方，以允许所述入射光在经过所述光电二极管210之后到达所述第一金属层240，且所述第一导电层234作为所述光电二极管210的下电极。因此，一些角度入射的入射光经过所述光电二极管210到达所述反射结构220和所述第一金属层240时被反射，重新回到所述光电二极管210中。某一些角度入射的入射光可能会在所述反射结构220和所述第一金属层240处经过多次反射，使得所述光电二极管210对入射光进行二次甚至多次吸收，提高光吸收率和量子效率(Quantum Efficiency，QE)。
需要说明的是，对于指纹识别等领域，更高的QE意味着可以有更多的有效信号被收集，从而可以提高指纹识别效率。
在本实施例中，仅位于所述光电二极管210的***区域下方的所述第一导电层234作为所述光电二极管210的下电极，即与图2所述的实施例相比，在本实施例中，所述光电二极管210的下电极较小。
在本实施例中，如图5所示，所述第一绝缘层232位于所述第一金属层240上方的部分形成所述第二透光介质层，也就是说，设置于所述第一金属 层240与所述光电二极管210的下表面之间的第二透光介质层，且所述第二透光介质层的厚度d2使得所述光电二极管210与所述第一金属层240之间满足针对所述入射光的光学谐振条件。
例如，在所述第一金属层240的材料确定的情况下，940纳米波长的单色光在硅(光电二极管)中的吸收比例随二氧化硅介质层(所述第二透光介质层)厚度d2变化的曲线如图3所示。根据公式3可以计算出，当d2＝144.9nm、468.8nm和792.6nm时，均可使所述光电二极管210与所述第一金属层240之间满足光学谐振条件，此时光电二极管210对这一单色光(940纳米波长)的吸收比例达到极大值，为38.5％。另外，可以看到若没有二氧化硅介质层，所述光电二极管210对这一单色光(940纳米波长)的吸收比例只有5％。
在本实施例中，如图5所示，所述反射结构220、所述第一绝缘层232和所述第一导电层234形成存储电容，以增加所述光电二极管210探测的动态范围。
需要说明的是，在本实施例中，为了确保入射光经过所述光电二极管210之后能够到达所述第一金属层240，所述第一导电层234仅延伸至所述光电二极管210的***区域下方，所以所述反射结构220、所述第一绝缘层232和所述第一导电层234形成的存储电容较小，所述光电二极管210的下电极也较小。对于指纹识别等领域，更高的QE意味着可以有更多的有效信号被收集，而电容更大程度上是为了增加探测的动态范围，因此在某些场景下为了获得更高的QE可以牺牲一部分电容容量，例如，将所述第一导电层234的延伸区域变小，只要可以作为所述光电二极管210的下电极使用即可。
应理解，除了所述第一绝缘层232和所述第一导电层234的设置不同外，图5和图2的其他设置相同，为了简洁，不再赘述。
可选地，在本申请一个实施例中，如图6所示，图4所示的实施例中的所述第一金属层240也作为一个反射结构，即所述反射结构220(所述第一金属层240)还设置于所述光电二极管210的下方。所述第一金属层240使不同角度入射的入射光在经过所述光电二极管210到达所述第一金属层240时被反射，重新回到所述光电二极管210中。
在前述图4所述的实施例中，所述第一绝缘层232和所述第一导电层234延伸至所述光电二极管210的下方，且所述第一导电层234作为所述光电二 极管210的下电极。在本实施例中，如图6所示，所述第一绝缘层232由透光绝缘材料形成，且所述第一绝缘层232延伸至所述光电二极管210的下方，并覆盖所述第一金属层240；所述第一导电层234延伸至所述光电二极管210的***区域下方，以允许所述入射光在经过所述光电二极管之后到达所述第一金属层240，且所述第一导电层234作为所述光电二极管210的下电极。
在本实施例中，如图6所示，所述第一绝缘层232位于所述第一金属层240上方的部分形成所述第二透光介质层，也就是说，设置于所述第一金属层240与所述光电二极管210的下表面之间的第二透光介质层，且所述第二透光介质层的厚度d2使得所述光电二极管210与所述第一金属层240之间满足针对所述入射光的光学谐振条件。
应理解，除了所述第一绝缘层232和所述第一导电层234的设置不同外，图6和图4的其他设置相同，为了简洁，不再赘述。
可选地，在本申请一个实施例中，如图7所示，所述第一金属层240作为一个反射结构，且在所述光电二极管的外侧或者内部未设置反射结构220，即所述反射结构220仅设置于所述光电二极管210的下方。所述第一金属层240使不同角度入射的入射光在经过所述光电二极管210到达所述第一金属层240时被反射，重新回到所述光电二极管210中。
在前述图5所述的实施例中，所述反射结构220设置于所述光电二极管210的外侧，且所述第一金属层240作为一个反射结构。在本实施例中，如图7所示，所述反射结构220仅设置于所述光电二极管210的下方，即仅所述第一金属层240作为一个反射结构。
应理解，除了未设置所述光电二极管210的外侧的所述反射结构220，图7和图5的其他设置相同，为了简洁，不再赘述。
可选地，在本申请一个实施例中，如图2、图4、图5、图6和图7所示，所述光电传感器200还可以包括：
遮光金属层260、连接电极270、接触电极280、绝缘保护层290和衬底20。
其中，所述遮光金属层260覆盖所述透光绝缘层250；所述连接电极270位于所述光电二极管210上；所述接触电极280位于所述连接电极270上，并且覆盖所述透光绝缘层250的部分区域，所述接触电极280连接所述光电二极管210与外部控制电路和/或电源，且所述连接电极270和所述接触电极 280透光，以允许不同角度入射的入射光进入所述光电二极管210；所述绝缘保护层290覆盖所述遮光金属层260和所述接触电极280，且所述绝缘保护层290透光以允许不同角度入射的入射光进入所述光电二极管210；所述薄膜晶体管230位于所述衬底20的第一区域，所述第一金属层240位于所述衬底20的第二区域。
需要说明的是，所述遮光金属层260用于阻止光照射入所述薄膜晶体管230。所述连接电极270和所述接触电极280的材料可以是氧化铟锡或者氧化锌等透光材料。所述衬底20的材料可以是透光材料，例如，所述衬底20为玻璃衬底。
图8和图9示出了本申请实施例的光电传感器200的光路图。
以所述反射结构220设置于所述光电二极管210的外侧为例，如图8所示，不同角度入射的入射光在经过所述绝缘保护层290、所述接触电极280、所述连接电极270之后进入所述光电二极管210，一些角度入射的入射光经过所述光电二极管210到达所述反射结构220时被反射，重新回到所述光电二极管210中。某一些角度入射的入射光可能会在所述反射结构220处经过多次反射，使得所述光电二极管210对入射光进行二次甚至多次吸收，提高光吸收率和量子效率。
以所述反射结构220设置于所述光电二极管210的外侧和下方(第一金属层240作为一个反射结构设置于所述光电二极管210的下方)为例，如图9所示，不同角度入射的入射光在经过所述绝缘保护层290、所述接触电极280、所述连接电极270之后进入所述光电二极管210，一些角度入射的入射光经过所述光电二极管210到达所述反射结构220和所述第一金属层240时被反射，重新回到所述光电二极管210中。某一些角度入射的入射光可能会在所述反射结构220和所述第一金属层240处经过多次反射，使得所述光电二极管210对入射光进行二次甚至多次吸收，提高光吸收率和量子效率。
本申请实施例提供的光电传感器中设置有反射结构，可以使不同角度入射的入射光在经过光电二极管到达反射结构时被反射，重新回到光电二极管中，能够提高人不可见的近红外光源的采集以及提高光电转换效率。
进一步地，在本申请实施例中，反射结构可以设置于光电二极管的外侧或者内部，也可以设置于光电二极管的下方，还可以同时设置于光电二极管的外侧或者内部以及光电二极管的下方，使得光电二极管区域对反射光进行 二次甚至更多次吸收，从而最大程度提高光吸收率。
以上描述了本申请实施例的光电传感器，下面描述本申请实施例的光电传感器的制备方法。本申请实施例的光电传感器的制备方法可以制备前述本申请实施例的光电传感器，下述实施例和前述实施例中的相关描述可以相互参考。
应理解，图10、图12和图14是本申请实施例的光电传感器的制作方法的示意性流程图，但这些步骤或操作仅是示例，本申请实施例还可以执行其他操作或者图10、图12和图14中的各个操作的变形。
图10示出了本申请实施例的光电传感器的制备方法300的示意性流程图。如图10所示，所述光电传感器的制备方法300包括：
301，制备第一结构，其中，所述第一结构包括薄膜晶体管、光电二极管、第一金属层、透光绝缘层和衬底，所述薄膜晶体管位于所述衬底的第一区域，所述第一金属层位于所述衬底的第二区域，所述光电二极管位于所述第一金属层的上方，所述透光绝缘层覆盖所述薄膜晶体管和所述光电二极管。
所述第一结构如图11a所示，可以经过标准TFT光电传感器制备工艺得到。
如图11a所示，所述薄膜晶体管230包括：栅极231，第一绝缘层232，沟道层233，第一导电层234和第二绝缘层235。具体地，所述第一绝缘层232覆盖于所述栅极231上，所述沟道层233位于所述第一绝缘层232上，所述第一导电层234位于所述沟道层233和所述第一绝缘层232上，所述第一导电层234上具有露出所述沟道层233的空隙，以将所述第一导电层234分隔为源极和漏极，所述第一绝缘层232和所述第一导电层234延伸至所述光电二极管210的下方，且所述第一导电层234作为所述光电二极管210的下电极，所述第二绝缘层235覆盖所述沟道层233和所述第一导电层234(除与所述光电二极管接触的区域)。
需要说明的是，所述薄膜晶体管230可以不包括所述第二绝缘层235，即所述透光绝缘层250可以直接覆盖所述沟道层233和所述第一导电层234。
如图11a所示，所述薄膜晶体管230位于所述衬底20的第一区域，所述第一金属层240位于所述衬底20的第二区域，所述光电二极管210位于所述第一金属层240的上方，所述透光绝缘层250覆盖所述薄膜晶体管230 和所述光电二极管210。
302，在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管。
可选地，可以采用深反应离子刻蚀(Deep Reactive Ion Etch，DRIE)对所述透光绝缘层250进行刻蚀处理，以制备沟槽结构30，并露出所述光电二极管210。
具体地，首先，在如图11a所示的第一结构中的所述透光绝缘层250上表面(正面)旋涂一层光刻胶，并曝光、显影，形成未覆盖光刻胶的刻蚀图形窗口。接着，通过深反应离子刻蚀，在所述透光绝缘层250中制作沟槽结构30。所述沟槽结构30自所述透光绝缘层250的上表面向下延伸至所述光电二极管210，如图11b所示。
应理解，在刻蚀出所述沟槽结构30之后，去除光刻胶。
303，在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光电二极管。
具体地，首先，在所述沟槽结构30中沉积第一透光导电材料，以形成所述连接电极270，如图11c所示。接着，通过沉积工艺，在所述连接电极270和所述透光绝缘层250上沉积第二透光导电材料，以形成第二透光导电层，以及在第二透光导电层的上表面覆盖一层光敏干膜，曝光、显影后形成覆盖所述第二透光导电层的干膜保护层，接着，用干法刻蚀去除未覆盖光敏干膜的第二透光导电层，最后去除光敏干膜，形成所述接触电极280，如图11d所示。
可选地，沉积所述连接电极270和/或所述接触电极280的工艺包括：原子层沉积(Atomic layer deposition，ALD)、物理气相沉积(Physical Vapor Deposition，PVD)、有机金属化学气相沉积、蒸镀、电镀等。
可选地，所述第一透光导电材料可以是氧化锌或者氧化铟锡，所述第二透光导电材料也可以是氧化锌或者氧化铟锡。
需要说明的是，所述第一透光导电材料和所述第二透光导电材料可以是相同的材料，即所述连接电极270和所述接触电极280可以是一个电极。
304，在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回 到所述光电二极管中。
具体地，首先，在如图11d所示的结构中的所述透光绝缘层250上表面(正面)旋涂一层光刻胶，并曝光、显影，形成未覆盖光刻胶的刻蚀图形窗口。接着，通过深反应离子刻蚀，在所述透光绝缘层250中制作深槽结构40，所述深槽结构40位于所述光电二极管210的外侧。所述深槽结构40自所述透光绝缘层250的上表面向下延伸，如图11e所示。在所述深槽结构40内沉积反射材料，以形成所述反射结构220，如图11f所示。
应理解，在刻蚀出所述深槽结构40之后，去除光刻胶。
可选地，可以直接利用空气作为反射介质(反射材料)，即不在所述深槽结构40内额外沉积材料。
可选地，在本申请实施例中，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
可选地，沉积所述反射结构220的工艺包括：ALD、PVD、有机金属化学气相沉积、蒸镀、电镀等。
可选地，在所述透光绝缘层上沿所述光电二极管的高度方向制备所述反射结构。即沿所述光电二极管的高度方向刻蚀所述深槽结构40。
可选地，位于所述反射结构220与所述光电二极管210的外壁之间的所述透光绝缘层250的厚度使得所述光电二极管210与所述反射结构220之间满足光学谐振条件。即可以通过光刻与刻蚀工艺的调控，控制所述深槽结构40与所述光电二极管210的外壁之间的介质层的厚度，从而优化反射体系，以使所述光电二极管210与所述反射结构220之间满足光学谐振条件。
可选地，所述反射结构220围绕所述光电二极管210连续或者离散分布。即通过光刻与刻蚀工艺，在光电二极管周围全部或部分介质层区域刻蚀出所述深槽结构40。
应理解，所述反射结构220的图案形状可根据光电传感器规格需求来设计，这里不再展开叙述。
305，在所述透光绝缘层和所述反射结构上方制备遮光金属层。
具体地，在如图11f所示的结构中，通过沉积和光刻工艺，在所述透光绝缘层250和所述反射结构220上方制备遮光金属层260，如图11g所示。
需要说明的是，步骤304和步骤305可以一并制备。
306，在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
具体地，在如图11g所示的结构中，通过沉积和光刻工艺，在所述遮光金属层和所述接触电极上制备透光的绝缘保护层，从而制备如图2所示的光电传感器。
在如图2所示的光电传感器200中，反射结构220设置于光电二极管210的外侧，可以使不同角度入射的入射光在经过光电二极管210到达反射结构220时被反射，重新回到光电二极管210中，光电二极管210区域对反射光可以进行二次甚至更多次吸收，从而提高人不可见的近红外光源的采集以及提高光电转换效率。
图12示出了本申请实施例的光电传感器的制备方法400的示意性流程图。如图12所示，所述光电传感器的制备方法400包括：
401，在衬底表面的第一区域制备底栅，以及在所述衬底表面的第二区域制备第一金属层。
具体地，首先，在衬底20上表面(正面)的第一区域制备底栅231(薄膜晶体管230的栅极231)，以及在所述衬底20上表面(正面)的第二区域制备第一金属层240，如图13a所示。
可选地，底栅231和第一金属层240可以同时制备，也可以分别制备。底栅231和第一金属层240的材料可以相同，也可以不同。底栅231和/或第一金属层240的材料例如可以为金属，例如，钼、铝或者钼铝合金等。
需要说明的是，401为底栅型TFT器件标准结构以及制备工艺(例如，沉积和光刻工艺)，在此不做赘述。
402，在所述衬底、所述底栅和所述第一金属层上制备透光的第一绝缘层。
具体地，在如图13a所示的结构上，通过沉积和光刻工艺，在所述衬底20、所述底栅231和所述第一金属层240上制备透光的第一绝缘层232，如图13b所示。
可选地，所述第一绝缘层的材料可以是氮化硅，氧化硅，或其他透明介质层材料，旋涂材料等。
403，在所述第一绝缘层上制备沟道层，所述沟道层位于所述底栅的上方。
具体地，在如图13b所示的结构上，通过沉积和光刻工艺，在所述第一绝缘层232上制备沟道层233，且所述沟道层233位于所述底栅231的上方， 如图13c所示。
所述沟道层233可以是α-Si薄膜的沟道(channel)。
404，在所述第一绝缘层和所述沟道层上制备第一导电层，其中，所述第一导电层包括露出所述沟道层的空隙，以将所述第一导电层分隔为源极和漏极，所述第一导电层延伸至所述第一金属层的上方，且露出部分位于所述第一金属层上方的所述第一绝缘层。
具体地，在如图13c所示的结构上，通过沉积和光刻工艺，在所述第一绝缘层232和所述沟道层233上制备第一导电层234，其中，所述第一导电层234包括露出所述沟道层233的空隙，以将所述第一导电层234分隔为源极和漏极，所述第一导电层234(例如，漏极部分)延伸至所述第一金属层240的上方，且露出部分位于所述第一金属层240上方的所述第一绝缘层232，如图13d所示。
可选地，在405之前，在如图13d所示的结构上，还可以通过沉积和光刻工艺制备第二绝缘层235，所述第二绝缘层235覆盖所述沟道层233和所述第一导电层234，且露出位于所述第一金属层240上方的所述第一绝缘层232和所述第一导电层234，如图13e所示。
可选地，所述第二绝缘层235的材料可以是氮化硅或氧化硅或旋涂材料。
可选地，可以在如图13d所示的结构上进行后续光电传感器的制备，也可以是在如图13e所示的结构上进行后续光电传感器的制备。以下以在如图13e所示的结构上进行后续光电传感器的制备为例进行说明。
405，在位于所述第一金属层上方的所述第一绝缘层和所述第一导电层上制备光电二极管。
具体地，在如图13e所示的结构上，在位于所述第一金属层240上方的所述第一绝缘层232和所述第一导电层234上制备光电二极管210，如图13f所示。
可选地，所述光电二极管210的形状可以是规则的，例如，可以是正方体、长方体、圆柱体等，当然，所述光电二极管210的形状也可以是不规则的。所述光电二极管210一般为三层结构，从上到下分别记为：P型无定型硅薄膜、本征无定型硅薄膜、N型无定型硅薄膜，P型无定型硅薄膜作为所述光电二极管210的阳极，N型无定型硅薄膜作为所述光电二极管210的阴极，本征无定型硅薄膜作为所述光电二极管210的光吸收层。
需要说明的是，405为光电二极管标准结构以及制备工艺(例如，沉积和光刻工艺)，在此不做赘述。
406，在所述第一绝缘层、所述第一导电层和所述光电二极管上制备透光绝缘层。
具体地，在如图13f所示的结构上，通过沉积和光刻工艺，在所述第一绝缘层232、所述第一导电层234和所述光电二极管210上制备透光绝缘层250，如图13g所示。
407，在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管。
具体地，在如图13g所示的结构上，中的所述透光绝缘层250上表面(正面)旋涂一层光刻胶，并曝光、显影，形成未覆盖光刻胶的刻蚀图形窗口。接着，通过深反应离子刻蚀，在所述透光绝缘层250中制作沟槽结构30。所述沟槽结构30自所述透光绝缘层250的上表面向下延伸至所述光电二极管210，如图13h所示。
应理解，在刻蚀出所述沟槽结构30之后，去除光刻胶。
408，在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光电二极管。
具体地，首先，在所述沟槽结构30中沉积第一透光导电材料，以形成所述连接电极，如图13i所示。接着，通过沉积工艺，在所述连接电极270和所述透光绝缘层250上沉积第二透光导电材料，以形成第二透光导电层，以及在第二透光导电层的上表面覆盖一层光敏干膜，曝光、显影后形成覆盖所述第二透光导电层的干膜保护层，接着，用干法刻蚀去除未覆盖光敏干膜的第二透光导电层，最后去除光敏干膜，形成所述接触电极280，如图13j所示。
可选地，沉积所述连接电极270和/或所述接触电极280的工艺包括：ALD、PVD、有机金属化学气相沉积、蒸镀、电镀等。
可选地，所述第一透光导电材料可以是氧化锌或者氧化铟锡，所述第二透光导电材料也可以是氧化锌或者氧化铟锡。
需要说明的是，所述第一透光导电材料和所述第二透光导电材料可以是相同的材料，即所述连接电极270和所述接触电极280可以是一个电极。
409，在所述透光绝缘层上方制备遮光金属层。
具体地，在如图13j所示的结构中，通过沉积和光刻工艺，在所述透光绝缘层250上方制备遮光金属层260，如图13k所示。
410，在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
具体地，在如图13k所示的结构中，通过沉积和光刻工艺，在所述遮光金属层和所述接触电极上制备透光的绝缘保护层，制备得到如图7所所示的光电传感器。
具体地，一些角度入射的入射光经过所述光电二极管210到达所述反射结构220和所述第一金属层240时被反射，重新回到所述光电二极管210中。某一些角度入射的入射光可能会在所述反射结构220和所述第一金属层240处经过多次反射，使得所述光电二极管210对入射光进行二次甚至多次吸收，提高光吸收率和量子效率。
可选地，位于所述第一金属层240与所述光电二极管210的下表面之间的所述第一绝缘层232的厚度使得所述光电二极管210与所述第一金属层240之间满足光学谐振条件。例如，在所述第一金属层240的材料确定的情况下，940纳米波长的单色光在硅(光电二极管)中的吸收比例随二氧化硅介质层(所述第二透光介质层)厚度d变化的曲线如图3所示。根据公式3可以计算出，当d＝144.9nm、468.8nm和792.6nm时，均可使所述光电二极管210与所述第一金属层240之间满足光学谐振条件，此时光电二极管210对这一单色光(940纳米波长)的吸收比例达到极大值，为38.5％。另外，可以看到若没有二氧化硅介质层，所述光电二极管210对这一单色光(940纳米波长)的吸收比例只有5％。
在如图7所示的光电传感器200中，反射结构(第一金属层240)设置于光电二极管210的下方，可以使不同角度入射的入射光在经过光电二极管210到达第一金属层240时被反射，重新回到光电二极管210中，光电二极管210区域对反射光可以进行二次甚至更多次吸收，从而提高人不可见的近红外光源的采集以及提高光电转换效率。
可选地，在制备所述遮光金属层之前，即在上述409之前，所述方法400还包括：
在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所 述光电二极管中。
具体地，首先，在如图13j所示的结构中的所述透光绝缘层250上表面(正面)旋涂一层光刻胶，并曝光、显影，形成未覆盖光刻胶的刻蚀图形窗口。接着，通过深反应离子刻蚀，在所述透光绝缘层250中制作深槽结构40，所述深槽结构40位于所述光电二极管210的外侧。所述深槽结构40自所述透光绝缘层250的上表面向下延伸，如图13l所示。在所述深槽结构40内沉积反射材料，以形成所述反射结构220，如图13m所示。具体地，在409中，可以是在如图13m所示的结构中的所述透光绝缘层250和所述反射结构220上方制备所述遮光金属层260，如图13n所示。在410中，可以是在如图13n所示的结构中的所述遮光金属层260和所述接触电极280上制备透光的绝缘保护层290，从而制备如图5所示的光电传感器。
应理解，在刻蚀出所述深槽结构40之后，去除光刻胶。
可选地，可以直接利用空气作为反射介质(反射材料)，即不在所述深槽结构40内额外沉积材料。
可选地，在本申请实施例中，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
可选地，沉积所述反射结构220的工艺包括：ALD、PVD、有机金属化学气相沉积、蒸镀、电镀等。
可选地，在所述透光绝缘层上沿所述光电二极管的高度方向制备所述反射结构。即沿所述光电二极管的高度方向刻蚀所述深槽结构40。
可选地，位于所述反射结构220与所述光电二极管210的外壁之间的所述透光绝缘层250的厚度使得所述光电二极管210与所述反射结构220之间满足光学谐振条件。即可以通过光刻与刻蚀工艺的调控，控制所述深槽结构40与所述光电二极管210的外壁之间的介质层的厚度，从而优化反射体系，以使所述光电二极管210与所述反射结构220之间满足光学谐振条件。
可选地，所述反射结构220围绕所述光电二极管210连续或者离散分布。即通过光刻与刻蚀工艺，在光电二极管周围全部或部分介质层区域刻蚀出所述深槽结构40。
应理解，所述反射结构220的图案形状可根据光电传感器规格需求来设计，这里不再展开叙述。
在如图5所示的光电传感器200中，反射结构220设置于光电二极管210 的外侧，以及反射结构(第一金属层240)设置于光电二极管210的下方，可以使不同角度入射的入射光在经过光电二极管210到达反射结构220和第一金属层240时被反射，重新回到光电二极管210中，光电二极管210区域对反射光可以进行二次甚至更多次吸收，从而提高人不可见的近红外光源的采集以及提高光电转换效率。
可选地，在制备所述透光绝缘层之前，即在上述406之前，所述方法400还包括：
在所述光电二极管上制备反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
具体地，首先，在如图13f所示的结构中的所述光电二极管210上表面(正面)旋涂一层光刻胶，并曝光、显影，形成未覆盖光刻胶的刻蚀图形窗口。接着，通过深反应离子刻蚀，在所述光电二极管210中制作深槽结构40，所述深槽结构40位于靠近所述光电二极管210的外壁的区域。所述深槽结构40自所述光电二极管210的上表面向下延伸，如图13o所示。在所述深槽结构40内沉积反射材料，以形成所述反射结构220，如图13p所示。具体地，在406中，可以是在如图13p所示的结构上，通过沉积和光刻工艺，在所述第一绝缘层232、所述第一导电层234、所述光电二极管210和所述反射结构220上制备透光绝缘层250，如图13q所示。以及经过后续407-410制备如图6所示的光电传感器。
应理解，在刻蚀出所述深槽结构40之后，去除光刻胶。
可选地，可以直接利用空气作为反射介质(反射材料)，即不在所述深槽结构40内额外沉积材料。
可选地，在本申请实施例中，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
可选地，沉积所述反射结构220的工艺包括：ALD、PVD、有机金属化学气相沉积、蒸镀、电镀等。
可选地，在所述光电二极管中沿所述光电二极管的高度方向制备所述反射结构。即沿所述光电二极管的高度方向刻蚀所述深槽结构40。
可选地，所述反射结构220在靠近所述光电二极管210的外壁的区域连续或者离散分布。即通过光刻与刻蚀工艺，在光电二极管中靠近所述光电二极管210的外壁的区域连续或者离散地刻蚀出所述深槽结构40。
应理解，所述反射结构220的图案形状可根据光电传感器规格需求来设计，这里不再展开叙述。
在如图6所示的光电传感器200中，反射结构220设置于光电二极管210的内部，以及反射结构(第一金属层240)设置于光电二极管210的下方，可以使不同角度入射的入射光在经过光电二极管210到达反射结构220和第一金属层240时被反射，重新回到光电二极管210中，光电二极管210区域对反射光可以进行二次甚至更多次吸收，从而提高人不可见的近红外光源的采集以及提高光电转换效率。
图14示出了本申请实施例的光电传感器的制备方法500的示意性流程图。如图14所示，所述光电传感器的制备方法500包括：
501，在衬底表面的第一区域制备底栅，以及在所述衬底表面的第二区域制备第一金属层。
502，在所述衬底、所述底栅和所述第一金属层上制备透光的第一绝缘层。
503，在所述第一绝缘层上制备沟道层，所述沟道层位于所述底栅的上方。
504，在所述第一绝缘层和所述沟道层上制备第一导电层，其中，所述第一导电层包括露出所述沟道层的空隙，以将所述第一导电层分隔为源极和漏极，所述第一导电层延伸至所述第一金属层的上方。
505，在位于所述第一金属层上方的所述第一导电层上制备光电二极管。
506，在所述光电二极管上制备反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中。
可选地，在所述光电二极管上靠近外壁的区域沿所述光电二极管的高度方向制备所述反射结构。
可选地，所述反射结构在靠近所述光电二极管的外壁的区域连续或者离散分布。
可选地，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
507，在所述第一绝缘层、所述第一导电层、所述反射结构和所述光电二极管上制备透光绝缘层。
508，在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管。
509，在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光电二极管。
510，在所述透光绝缘层上方制备遮光金属层。
511，在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
具体地，所述光电传感器的制备方法500可以制备如图4所示的光电传感器。
在如图4所示的光电传感器200中，反射结构220设置于光电二极管210的内部，可以使不同角度入射的入射光在经过光电二极管210到达反射结构220时被反射，重新回到光电二极管210中，光电二极管210区域对反射光可以进行二次甚至更多次吸收，从而提高人不可见的近红外光源的采集以及提高光电转换效率。
应理解，光电传感器的制备方法500中的步骤可以参考光电传感器的制备方法300和光电传感器的制备方法400中的相应步骤，为了简洁，在此不再赘述。
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。
本领域普通技术人员可以意识到，以上结合附图详细描述了本申请的优选实施方式，但是，本申请并不限于上述实施方式中的具体细节，在本申请的技术构思范围内，可以对本申请的技术方案进行多种简单变型，这些简单变型均属于本申请的保护范围。
另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合，为了避免不必要的重复，本申请对各种可能的组合方式不再另行说明。
此外，本申请的各种不同的实施方式之间也可以进行任意组合，只要其不违背本申请的思想，其同样应当视为本申请所申请的内容。应理解，在本申请实施例和所附权利要求书中使用的术语是仅仅出于描述特定实施例的目的，而非旨在限制本申请实施例。例如，在本申请实施例和所附权利要求书中所使用的单数形式的“一种”、“上述”和“该”也旨在包括多数形式，除非上下文清楚地表示其他含义。
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，可轻易想到各种等效的修改或替换，这些修改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权利要求的保护范围为准。

Claims (35)

  1. 一种光电传感器，其特征在于，包括：光电二极管和反射结构，
    其中，所述反射结构设置于所述光电二极管的外侧或者内部，和/或，所述反射结构设置于所述光电二极管的下方，以使不同角度入射的入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中。
  2. 根据权利要求1所述的光电传感器，其特征在于，所述反射结构沿所述光电二极管的高度方向设置于所述光电二极管的外侧或者内部。
  3. 根据权利要求1或2所述的光电传感器，其特征在于，若所述反射结构设置于所述光电二极管的外侧，在所述反射结构与所述光电二极管的外壁之间设置有第一透光介质层，且所述第一透光介质层的厚度使得所述光电二极管与所述反射结构之间满足针对所述入射光的光学谐振条件。
  4. 根据权利要求3所述的光电传感器，其特征在于，所述反射结构围绕所述光电二极管连续或者离散分布。
  5. 根据权利要求1或2所述的光电传感器，其特征在于，若所述反射结构设置于所述光电二极管的内部，所述反射结构位于靠近所述光电二极管的外壁的区域。
  6. 根据权利要求5所述的光电传感器，其特征在于，所述反射结构在靠近所述光电二极管的外壁的区域连续或者离散分布。
  7. 根据权利要求1所述的光电传感器，其特征在于，所述反射结构沿所述光电二极管的水平方向设置于所述光电二极管的下方。
  8. 根据权利要求1或7所述的光电传感器，其特征在于，若所述反射结构设置于所述光电二极管的下方，在所述反射结构与所述光电二极管的下表面之间设置有第二透光介质层，且所述第二透光介质层的厚度使得所述光电二极管与所述反射结构之间满足针对所述入射光的光学谐振条件。
  9. 根据权利要求8所述的光电传感器，其特征在于，所述反射结构还用于阻挡光从所述光电二极管的下方进入所述光电二极管。
  10. 根据权利要求8或9所述的光电传感器，其特征在于，所述光电二极管的下电极位于所述光电二极管与所述反射结构之间，且所述光电二极管的下电极位于所述光电二极管的***区域下方，以允许所述入射光在经过所述光电二极管之后到达所述反射结构。
  11. 根据权利要求10所述的光电传感器，其特征在于，所述光电传感器还包括薄膜晶体管，所述薄膜晶体管与所述光电二极管构成所述光电传感器的像素单元。
  12. 根据权利要求11所述的光电传感器，其特征在于，所述薄膜晶体管包括：
    栅极，
    覆盖于所述栅极上的由透光绝缘材料形成的第一绝缘层，
    位于所述第一绝缘层上的沟道层，
    位于所述沟道层上的第一导电层，所述第一导电层上具有露出所述沟道层的空隙，以将所述第一导电层分隔为源极和漏极，
    其中，所述第一绝缘层延伸至所述光电二极管的下方，且位于所述反射结构上方的部分形成所述第二透光介质层；所述第一导电层延伸至所述光电二极管的***区域下方，以形成所述光电二极管的下电极。
  13. 根据权利要求12所述的光电传感器，其特征在于，所述反射结构、所述第一绝缘层和所述第一导电层形成存储电容，以增加所述光电二极管探测的动态范围。
  14. 根据权利要求1至6中任一项所述的光电传感器，其特征在于，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
  15. 根据权利要求7至13中任一项所述的光电传感器，其特征在于，所述反射结构的反射材料为金属。
  16. 根据权利要求1至15中任一项所述的光电传感器，其特征在于，所述入射光为近红外光。
  17. 一种光电传感器的制备方法，其特征在于，包括：
    制备第一结构，其中，所述第一结构包括薄膜晶体管、光电二极管、第一金属层、透光绝缘层和衬底，所述薄膜晶体管位于所述衬底的第一区域，所述第一金属层位于所述衬底的第二区域，所述光电二极管位于所述第一金属层的上方，所述透光绝缘层覆盖所述薄膜晶体管和所述光电二极管；
    在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管；
    在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光 电二极管；
    在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
    在所述透光绝缘层和所述反射结构上方制备遮光金属层；
    在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
  18. 根据权利要求17所述的方法，其特征在于，所述在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，包括：
    在所述透光绝缘层上沿所述光电二极管的高度方向制备所述反射结构。
  19. 根据权利要求17或18所述的方法，其特征在于，位于所述反射结构与所述光电二极管的外壁之间的所述透光绝缘层的厚度使得所述光电二极管与所述反射结构之间满足光学谐振条件。
  20. 根据权利要求17至19中任一项所述的方法，其特征在于，所述反射结构围绕所述光电二极管连续或者离散分布。
  21. 根据权利要求17至20中任一项所述的方法，其特征在于，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
  22. 一种光电传感器的制备方法，其特征在于，包括：
    在衬底表面的第一区域制备底栅，以及在所述衬底表面的第二区域制备第一金属层；
    在所述衬底、所述底栅和所述第一金属层上制备透光的第一绝缘层；
    在所述第一绝缘层上制备沟道层，所述沟道层位于所述底栅的上方；
    在所述第一绝缘层和所述沟道层上制备第一导电层，其中，所述第一导电层包括露出所述沟道层的空隙，以将所述第一导电层分隔为源极和漏极，所述第一导电层延伸至所述第一金属层的上方，且露出部分位于所述第一金属层上方的所述第一绝缘层；
    在位于所述第一金属层上方的所述第一绝缘层和所述第一导电层上制备光电二极管；
    在所述第一绝缘层、所述第一导电层和所述光电二极管上制备透光绝缘层；
    在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管；
    在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘 层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光电二极管；
    在所述透光绝缘层上方制备遮光金属层；
    在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
  23. 根据权利要求22所述的方法，其特征在于，位于所述第一金属层与所述光电二极管的下表面之间的所述第一绝缘层的厚度使得所述光电二极管与所述第一金属层之间满足光学谐振条件。
  24. 根据权利要求22或23所述的方法，其特征在于，在制备所述遮光金属层之前，所述方法还包括：
    在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
    所述在所述透光绝缘层上方制备遮光金属层，包括：
    在所述透光绝缘层和所述反射结构上方制备所述遮光金属层。
  25. 根据权利要求24所述的方法，其特征在于，所述在所述透光绝缘层上制备位于所述光电二极管的外侧的反射结构，包括：
    在所述透光绝缘层上沿所述光电二极管的高度方向制备所述反射结构。
  26. 根据权利要求24或25所述的方法，其特征在于，位于所述反射结构与所述光电二极管的外壁之间的所述透光绝缘层的厚度使得所述光电二极管与所述反射结构之间满足光学谐振条件。
  27. 根据权利要求24至26中任一项所述的方法，其特征在于，所述反射结构围绕所述光电二极管连续或者离散分布。
  28. 根据权利要求22或23所述的方法，其特征在于，在制备所述透光绝缘层之前，所述方法还包括：
    在所述光电二极管上制备反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
    所述在所述第一绝缘层、所述第一导电层和所述光电二极管上制备透光绝缘层，包括：
    在所述第一绝缘层、所述第一导电层、所述反射结构和所述光电二极管上制备透光绝缘层。
  29. 根据权利要求28所述的方法，其特征在于，所述在所述光电二极管上制备反射结构，包括：
    在所述光电二极管上靠近外壁的区域沿所述光电二极管的高度方向制备所述反射结构。
  30. 根据权利要求29所述的方法，其特征在于，所述反射结构在靠近所述光电二极管的外壁的区域连续或者离散分布。
  31. 根据权利要求22至30中任一项所述的方法，其特征在于，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
  32. 一种光电传感器的制备方法，其特征在于，包括：
    在衬底表面的第一区域制备底栅，以及在所述衬底表面的第二区域制备第一金属层；
    在所述衬底、所述底栅和所述第一金属层上制备透光的第一绝缘层；
    在所述第一绝缘层上制备沟道层，所述沟道层位于所述底栅的上方；
    在所述第一绝缘层和所述沟道层上制备第一导电层，其中，所述第一导电层包括露出所述沟道层的空隙，以将所述第一导电层分隔为源极和漏极，所述第一导电层延伸至所述第一金属层的上方；
    在位于所述第一金属层上方的所述第一导电层上制备光电二极管；
    在所述光电二极管上制备反射结构，以使所述入射光在经过所述光电二极管到达所述反射结构时被反射，重新回到所述光电二极管中；
    在所述第一绝缘层、所述第一导电层、所述反射结构和所述光电二极管上制备透光绝缘层；
    在所述透光绝缘层上制备沟槽结构，以露出所述光电二极管；
    在所述沟槽结构内制备连接电极，以及在所述连接电极和所述透光绝缘层上制备接触电极，以连接所述光电二极管与外部控制电路和/或电源，且所述连接电极和所述接触电极透光，以允许不同角度入射的入射光进入所述光电二极管；
    在所述透光绝缘层上方制备遮光金属层；
    在所述遮光金属层和所述接触电极上制备透光的绝缘保护层。
  33. 根据权利要求32所述的方法，其特征在于，所述在所述光电二极管上制备反射结构，包括：
    在所述光电二极管上靠近外壁的区域沿所述光电二极管的高度方向制 备所述反射结构。
  34. 根据权利要求33所述的方法，其特征在于，所述反射结构在靠近所述光电二极管的外壁的区域连续或者离散分布。
  35. 根据权利要求32至34中任一项所述的方法，其特征在于，所述反射结构的反射材料为空气、金属、二氧化硅、复合材料中的至少一种。
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