WO2020150938A1

WO2020150938A1 - Photoelectric sensor and preparation method therefor

Info

Publication number: WO2020150938A1
Application number: PCT/CN2019/072864
Authority: WO
Inventors: 王文轩; 沈健; 姚国峰; 李运宁
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2019-01-23
Filing date: 2019-01-23
Publication date: 2020-07-30
Also published as: CN109863509A; CN109863509B

Abstract

Provided in the present application are a photoelectric sensor and preparation method therefor, which may improve the acquisition of near infrared light sources which humans cannot see and improve photoelectric conversion efficiency. The photoelectric sensor comprises: a photoelectric diode and a reflection structure, wherein the reflection structure is arranged at the outer side or the interior of the photoelectric diode, and/or the reflection structure is arranged below the photoelectric diode so that incident light which is incident at different angles is reflected when reaching the reflection structure by traversing the photoelectric diode and is returned back into the photoelectric diode.

Description

Photoelectric sensor and preparation method thereof

Technical field

This application relates to the field of photoelectric sensors, and more specifically, to a photoelectric sensor and a preparation method thereof.

Background technique

The photoelectric sensor is a device that converts light signals into electrical signals based on the photoelectric effect. Among them, 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.

In recent years, with the development of medical imaging, fingerprint image acquisition, and fingerprint recognition markets, thin film transistor photoelectric sensors have been widely used. However, since the wavelength of near-infrared light (780-2526nm) is longer than that of visible light (380-780nm), in the photodiode structure of the thin film transistor photoelectric sensor, the absorption rate of near-infrared light is low, and at the same time, the infrared wavelength is easy to Through the photodiode structure of the thin film transistor photo sensor, the absorption efficiency is further reduced. Therefore, how to improve the collection of Near Infrared (NIR) light sources that are invisible to human eyes and improve the photoelectric conversion efficiency has become one of the urgent problems in the field of thin film transistor photoelectric sensors.

Summary of the invention

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.

In the first aspect, a photoelectric sensor is provided, including: a photodiode and a reflective structure,

Wherein, 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.

Further, in the embodiments of the present application, 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.

In some possible implementation manners, the reflective structure is arranged outside or inside the photodiode along the height direction of the photodiode.

In some possible implementations, if the reflective structure is arranged on the outside 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.

It should be understood that when the optical resonance condition for the incident light is satisfied between the photodiode and the reflective structure, the absorption ratio of the photodiode to the incident light reaches a maximum value.

In some possible implementations, the reflective structure is continuously or discretely distributed around the photodiode.

Assuming that the photodiode is a cube, the four side surfaces are denoted as a, b, c, and d, and the two bottom surfaces are denoted as e and f, respectively. For example, the reflective structure surrounds the photodiode and is continuously distributed on the outside of the four sides a, b, c, and d. For another example, the reflective structure surrounds the photodiode and is discretely distributed on the outer sides of the two sides a and c. For another example, 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.

In some possible implementations, 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.

It should be noted that 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.

In some possible implementations, the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.

Assuming that the photodiode is a cube, the four side surfaces are denoted as a, b, c, and d, and the two bottom surfaces are denoted as e and f, respectively. For example, the reflective structure is continuously distributed in areas close to the four sides of the photodiode, a, b, c, and d. For another example, the reflective structure is discretely distributed in areas close to the b and d sides of the photodiode. For another example, 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.

In some possible implementation manners, the reflective structure is arranged below the photodiode along the horizontal direction of the photodiode.

It should be noted that the horizontal direction of the photodiode may be a direction perpendicular to the height direction of the photodiode.

In some possible implementations, if the reflective structure is arranged below 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.

It should be understood that when the optical resonance condition for the incident light is satisfied between the photodiode and the reflective structure, the absorption ratio of the photodiode to the reflected light reaches a maximum.

In some possible implementation manners, the reflective structure is also used to block light from entering the photodiode from below the photodiode.

In some possible implementations, 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.

It should be understood that 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.

In some possible implementation manners, the photosensor further includes a thin film transistor, and the thin film transistor and the photodiode constitute a pixel unit of the photosensor.

Optionally, in the embodiment of the present application, the photosensor may include at least one pixel unit, and each pixel unit includes a thin film transistor and a photodiode.

In some possible implementation manners, the thin film transistor includes:

Grid,

A first insulating layer formed of a light-transmitting insulating material covering the gate,

A channel layer located on the first insulating layer,

A first conductive layer located on the channel layer and the first insulating layer, the first conductive layer has a gap exposing the channel layer to separate the first conductive layer into a source and Drain,

Wherein, 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.

In some possible implementation manners, 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.

In some possible implementations, if the reflective structure is arranged outside or inside the photodiode, the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.

It should be noted that if the reflective material of the reflective structure is air, the reflective structure may be a trench structure, and the trench structure is not filled with other materials except air.

In some possible implementations, if the reflective structure is disposed under the photodiode, the reflective material of the reflective structure is metal.

In some possible implementations, the incident light is near-infrared light.

In the second aspect, a method for manufacturing a photoelectric sensor is provided, 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;

Preparing a trench structure on the transparent insulating layer to expose 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;

Preparing a reflective structure located on the outer side of the photodiode 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;

Preparing a light-shielding metal layer on the transparent insulating layer and the reflective structure;

A transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode.

In some possible implementation manners, 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.

In some possible implementation manners, 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.

In some possible implementation manners, the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.

In a third aspect, a method for manufacturing a photoelectric sensor is provided, including:

Preparing a bottom gate in a first area on the surface of the substrate, and preparing a first metal layer in a second area on the surface of the substrate;

Preparing a transparent first insulating layer on the substrate, the bottom gate and the first metal layer;

Preparing a channel layer on the first insulating layer, the channel layer being located above the bottom gate;

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;

Preparing a photodiode on the first insulating layer and the first conductive layer located above the first metal layer;

Preparing a light-transmitting insulating layer on the first insulating layer, the first conductive layer and the photodiode;

Preparing a light-shielding metal layer on the transparent insulating layer;

In some possible implementations, 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.

In some possible implementation manners, 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.

In some possible implementation manners, 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.

In some possible implementation manners, before preparing the transparent insulating layer, the method further includes:

Preparing a reflective structure on the photodiode, so that the incident light is reflected when it reaches the reflective structure through the photodiode and returns to the photodiode;

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.

In some possible implementation manners, 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.

In a fourth aspect, a method for manufacturing a photoelectric sensor is provided, 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;

Preparing a photodiode on the first conductive layer located above the first metal layer;

Preparing a light-transmitting insulating layer on the first insulating layer, the first conductive layer, the reflective structure and the photodiode;

Preparing a light-shielding metal layer on the transparent insulating layer;

In a fifth aspect, an electronic device is provided, including the photoelectric sensor as described in the first aspect and any possible implementation of the first aspect.

Description of the drawings

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.

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.

detailed description

The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings.

It should be understood that 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 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.

It should also be understood that, in the embodiments of the present application, 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. 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.

As a common application scenario, 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. Alternatively, 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.

As shown in 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. As shown in FIG. 1, the fingerprint detection area 103 is located in the display area of the display screen 120. In an alternative embodiment, 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.

It should be understood that 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. In other alternative implementations, if for example a light collimation method is used for light path guidance, 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.

Therefore, when the user needs to unlock the terminal device or perform other fingerprint verification, he only needs to press his finger on the fingerprint detection area 103 located in the display screen 120 to realize fingerprint input. Since fingerprint detection can be implemented in the screen, 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.

As an optional implementation, as shown in FIG. 1, 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.

In terms of specific implementation, the optical assembly 132 and the light detecting part 134 may be packaged in the same optical fingerprint component. For example, 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.

Wherein, the light guide layer or light path guiding structure of the optical component 132 has multiple implementation schemes. For example, 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.

In another embodiment, 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. Optionally, 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.

In other embodiments, 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. In addition, 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. More specifically, 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. It should be understood that several implementation solutions of the above-mentioned optical path guiding structure can be used alone or in combination. For example, a microlens layer can be further provided under the collimator layer or the optical lens layer. Of course, when 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.

As an optional embodiment, 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. Taking an OLED display screen as an example, 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. When the finger 140 is pressed on the fingerprint detection area 103, 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. In related patent applications, for ease of description, 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. After 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.

In other embodiments, 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. In this case, 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. Taking a liquid crystal display with a backlight module and a liquid crystal panel as an example, in order to support the under-screen fingerprint detection of the liquid crystal display, 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. . When 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.

It should be understood that, in specific implementation, 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.

On the other hand, in some embodiments, the optical fingerprint device 130 may include only one optical fingerprint sensor. At this time, 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. In other alternative embodiments, 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. In other words, 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. Alternatively, when the number of optical fingerprint sensors is sufficient, 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.

It should be noted that the embodiment of the present application takes a thin film transistor photoelectric sensor as an example for detailed description. Specifically, in the embodiments of the present application, since the wavelength of near-infrared light (780-2526nm) is longer than that of visible light (380-780nm), in the photodiode structure of the thin film transistor photoelectric sensor, 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. Based on the above-mentioned problems, the present application provides a reflective structure in the photoelectric sensor. By controlling the thickness of the dielectric layer between the photodiode and the reflective structure, 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.

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.

As shown in FIG. 2, 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.

Optionally, the incident light may be visible light and/or infrared light, for example, it may be near-infrared light.

In the embodiment of the present application, 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 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.

Optionally, the reflective structure 220 is continuously or discretely distributed around the photodiode 210.

Assuming that 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. For example, 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. For another example, the reflective structure 220 surrounds the photodiode 210 and is discretely distributed on the outer sides of the two sides a and c. For another example, 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.

In the embodiment of the present application, the shape and size of the reflective structure 220 can be set according to actual needs. For example, 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.

Optionally, as shown in FIG. 2, the reflective structure 220 is arranged outside the photodiode 210 along the height direction of the photodiode 210.

It should be noted that 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.

Optionally, the reflective material of the reflective structure 220 is at least one of air, metal, silicon dioxide, and composite materials.

It should be noted that if the reflective material of the reflective structure 220 is air, the reflective structure 220 can be a trench structure, and the trench structure is not filled with other materials except air.

Optionally, 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.

It should be understood that when the optical resonance condition for incident light is satisfied between the photodiode 210 and the reflective structure 220, the absorption rate of the photodiode 210 for incident light reaches a maximum.

It should be noted that when a beam of vertically incident single wavelength incident light enters the photodiode, it will be reflected at the interface between the air and the photodiode, the interface between the photodiode and the dielectric layer, and the interface between the dielectric layer and the reflective structure. 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 2π, that is, the formation Standing wave.

When the thickness d of the dielectric layer changes, it will cause the above-mentioned phase change θ, as shown in formula 1.

Among them, d is the thickness of the dielectric layer, and λ is the wavelength of monochromatic light.

The absorption of light by the reflective structure causes a phase change

As shown in formula 2,

Among them, n _d is the refractive index of the dielectric layer, n _r is the refractive index of the reflective structure, and k _r is the extinction coefficient of the reflective structure.

The conditions for forming a standing wave are shown in formula 3.

It can be seen from formulas 1 to 3 that when the reflective structure material is determined, only the thickness of the dielectric layer meets the specific requirements, and the conditions for forming a standing wave for incident light of a specific wavelength can be obtained.

That is to say, in the embodiment of the present application, when the material of the reflective structure 220 is determined, 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.

For example, when the material of the reflective structure 220 is determined, the absorption ratio of monochromatic light with a wavelength of 940 nanometers in silicon (photodiode) varies with the thickness d1 of the silicon dioxide dielectric layer as shown in FIG. 3. According to formula 3, it can be calculated that when d1=144.9nm, 468.8nm and 792.6nm, the optical resonance conditions between the photodiode 210 and the reflective structure 220 can be satisfied. The absorption ratio of light (940 nm wavelength) reaches the maximum value of 38.5%. In addition, it can be seen that if there is no silicon dioxide dielectric layer, the absorption ratio of the photodiode 210 to this monochromatic light (940 nm wavelength) is only 5%.

Optionally, in an embodiment of the present application, 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.

Optionally, the photosensor 200 may include at least one pixel unit, and each pixel unit includes a thin film transistor and a photodiode.

Optionally, as shown in FIG. 2, the thin film transistor 230 includes:

Gate 231, first insulating layer 232, channel layer 233, first conductive layer 234.

Wherein, 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. On the first insulating layer 232, 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.

It should be noted that, in this embodiment, 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 α-Si thin film.

Optionally, as shown in FIG. 2, 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.

Optionally, as shown in FIG. 2, 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. At the same time, the first insulating layer 232 extends below the photodiode 210 and covers the first metal layer 240.

Optionally, as shown in FIG. 2, 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.

As shown in FIG. 2, 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 For the first light-transmitting medium layer, 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.

Optionally, in an embodiment of the present application, as shown in FIG. 4, 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. When the reflective structure 220 is reflected, it returns to the photodiode 210 again.

In the aforementioned embodiment described in FIG. 2, the reflective structure 220 is disposed outside the photodiode 210. In this embodiment, as shown in FIG. 4, the reflective structure 220 is disposed inside the photodiode 210. For example, the reflective structure 220 is located in an area close to the outer wall of the photodiode 210. Optionally, the reflective structure 220 is disposed inside the photodiode 210 along the height direction of the photodiode 210. Since 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.

Optionally, as shown in FIG. 4, the reflective structure 220 is continuously or discretely distributed in a region close to the outer wall of the photodiode 210.

Assuming that 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. For example, the reflective structure 220 is continuously distributed in the area close to the four sides a, b, c, and d of the photodiode 210. For another example, the reflective structure 220 is discretely distributed in areas close to the b and d sides of the photodiode 210. For another example, 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.

It should be understood that, except for the different positions of the reflective structure 220, the other settings of FIG. 4 and FIG. 2 are the same, and for the sake of brevity, details are not described again.

Optionally, in an embodiment of the present application, as shown in FIG. 5, 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.

In the aforementioned embodiment of FIG. 2, 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. In this embodiment, as shown in FIG. 5, 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. 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 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).

It should be noted that for fingerprint recognition and other fields, higher QE means that more effective signals can be collected, which can improve the efficiency of fingerprint recognition.

In this embodiment, only the first conductive layer 234 located below the peripheral area of the photodiode 210 serves as the lower electrode of the photodiode 210, that is, compared with the embodiment shown in FIG. 2, in this embodiment In an example, the lower electrode of the photodiode 210 is relatively small.

In this embodiment, as shown in FIG. 5, 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.

For example, when the material of the first metal layer 240 is determined, 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 d2 change is shown in Figure 3. According to formula 3, it can be calculated that when d2=144.9nm, 468.8nm and 792.6nm, the optical resonance conditions between the photodiode 210 and the first metal layer 240 can be satisfied, and the photodiode 210 is The absorption ratio of a monochromatic light (940 nm wavelength) reaches the maximum value of 38.5%. In addition, it can be seen that if there is no silicon dioxide dielectric layer, the absorption ratio of the photodiode 210 to this monochromatic light (940 nm wavelength) is only 5%.

In this embodiment, as shown in FIG. 5, 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.

It should be noted that, in this embodiment, in order to ensure that the incident light can reach the first metal layer 240 after passing through the photodiode 210, 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. For fingerprint recognition and other fields, 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.

It should be understood that, except for the different settings of the first insulating layer 232 and the first conductive layer 234, the other settings of FIG. 5 and FIG. 2 are the same, and for the sake of brevity, details are not described again.

Optionally, in an embodiment of the present application, as shown in FIG. 6, 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.

In the aforementioned embodiment of FIG. 4, 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. In this embodiment, as shown in FIG. 6, 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.

In this embodiment, as shown in FIG. 6, 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.

It should be understood that, except for the different settings of the first insulating layer 232 and the first conductive layer 234, the other settings of FIG. 6 and FIG. 4 are the same, and will not be repeated for the sake of brevity.

Optionally, in an embodiment of the present application, as shown in FIG. 7, 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.

In the embodiment described in FIG. 5, the reflective structure 220 is disposed on the outside of the photodiode 210, and the first metal layer 240 serves as a reflective structure. In this embodiment, as shown in FIG. 7, the reflective structure 220 is only disposed under the photodiode 210, that is, only the first metal layer 240 serves as a reflective structure.

It should be understood that, except that the reflective structure 220 on the outer side of the photodiode 210 is not provided, the other settings of FIG. 7 and FIG. 5 are the same, and for the sake of brevity, details are not described again.

Optionally, in an embodiment of the present application, as shown in FIG. 2, FIG. 4, FIG. 5, FIG. 6 and FIG. 7, 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.

Wherein, 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.

It should be noted that 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.

8 and 9 show the optical path diagram of the photoelectric sensor 200 according to the embodiment of the present application.

Taking the reflective structure 220 disposed on the outside of the photodiode 210 as an example, as shown in FIG. 8, 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.

Taking the reflective structure 220 arranged on the outside and under the photodiode 210 (the first metal layer 240 is arranged under the photodiode 210 as a reflective structure) as an example, as shown in 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.

Further, in the embodiment of the present application, 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.

It should be understood that 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:

301. Prepare a first structure, wherein 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.

As shown in FIG. 11a, 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. Specifically, 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 On the first insulating layer 232, 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).

It should be noted that 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.

As shown in FIG. 11a, 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. Above the metal layer 240, the transparent insulating layer 250 covers the thin film transistor 230 and the photodiode 210.

302. Prepare a trench structure on the transparent insulating layer to expose the photodiode.

Optionally, Deep Reactive Ion Etch (DRIE) may be used to etch the light-transmitting insulating layer 250 to prepare the trench structure 30 and expose the photodiode 210.

Specifically, first, 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. Then, 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.

It should be understood that after the trench structure 30 is etched, the photoresist is removed.

303. Prepare 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.

Specifically, first, a first light-transmitting conductive material is deposited in the trench structure 30 to form the connection electrode 270, as shown in FIG. 11c. Next, by a deposition process, 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. Then, 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.

Optionally, 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.

Optionally, the first transparent conductive material may be zinc oxide or indium tin oxide, and the second transparent conductive material may also be zinc oxide or indium tin oxide.

It should be noted that the 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.

304. Prepare a reflective structure located on the outside of the photodiode 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 in.

Specifically, first, 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. Then, by deep reactive ion etching, 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.

It should be understood that after the deep trench structure 40 is etched, the photoresist is removed.

Optionally, air can be directly used as a reflective medium (reflective material), that is, no additional material is deposited in the deep groove structure 40.

Optionally, in the embodiment of the present application, the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite material.

Optionally, the process for depositing the reflective structure 220 includes: ALD, PVD, metal organic chemical vapor deposition, evaporation, electroplating, and the like.

Optionally, 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.

Optionally, 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.

Optionally, 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.

It should be understood that 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.

305. Prepare a light-shielding metal layer on the transparent insulating layer and the reflective structure.

Specifically, in the structure shown in FIG. 11f, 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.

It should be noted that step 304 and step 305 can be prepared together.

306. Prepare a transparent insulating protective layer on the light-shielding metal layer and the contact electrode.

Specifically, in the structure shown in FIG. 11g, 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 .

In the photoelectric sensor 200 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. In the photodiode 210 region, 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:

401. Prepare a bottom gate in a first area on the surface of a substrate, and prepare a first metal layer in a second area on the surface of the substrate.

Specifically, first, 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.

Optionally, 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.

It should be noted that 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.

402. Prepare a transparent first insulating layer on the substrate, the bottom gate and the first metal layer.

Specifically, on the structure shown in FIG. 13a, 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.

Optionally, 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.

403. Prepare a channel layer on the first insulating layer, where the channel layer is located above the bottom gate.

Specifically, on the structure shown in FIG. 13b, 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 α-Si thin film.

404. Prepare a 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 For the source electrode and the drain electrode, the first conductive layer extends above the first metal layer and exposes a portion of the first insulating layer above the first metal layer.

Specifically, on the structure shown in FIG. 13c, 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. Above the metal layer 240, and partially expose the first insulating layer 232 above the first metal layer 240, as shown in FIG. 13d.

Optionally, before 405, on the structure shown in FIG. 13d, 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.

Optionally, the material of the second insulating layer 235 may be silicon nitride or silicon oxide or a spin-on material.

Optionally, 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.

405. Prepare a photodiode on the first insulating layer and the first conductive layer located above the first metal layer.

Specifically, 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 .

Optionally, 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 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.

It should be noted that 405 is the standard structure of the photodiode and the preparation process (for example, deposition and photolithography process), which will not be repeated here.

406. Prepare a light-transmitting insulating layer on the first insulating layer, the first conductive layer, and the photodiode.

Specifically, on the structure shown in FIG. 13f, 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.

407. Prepare a trench structure on the transparent insulating layer to expose the photodiode.

Specifically, on the structure shown in FIG. 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. Then, 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.

408. Prepare 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.

Specifically, first, a first transparent conductive material is deposited in the trench structure 30 to form the connection electrode, as shown in FIG. 13i. Next, by a deposition process, 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. Then, 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.

Optionally, 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.

409: Prepare a light-shielding metal layer on the transparent insulating layer.

Specifically, in the structure shown in FIG. 13j, a light-shielding metal layer 260 is prepared on the transparent insulating layer 250 through deposition and photolithography processes, as shown in FIG. 13k.

410. Prepare a light-transmitting insulating protection layer on the light-shielding metal layer and the contact electrode.

Specifically, in the structure shown in FIG. 13k, through deposition and photolithography processes, 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.

Specifically, 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.

Optionally, 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. For example, when the material of the first metal layer 240 is determined, 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. According to formula 3, it can be calculated that when d=144.9nm, 468.8nm and 792.6nm, the optical resonance conditions between the photodiode 210 and the first metal layer 240 can be satisfied. The absorption ratio of a monochromatic light (940 nm wavelength) reaches the maximum value of 38.5%. In addition, it can be seen that if there is no silicon dioxide dielectric layer, the absorption ratio of the photodiode 210 to this monochromatic light (940 nm wavelength) is only 5%.

In the photoelectric sensor 200 shown in FIG. 7, 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.

Optionally, before preparing the light-shielding metal layer, that is, before the foregoing 409, 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.

Specifically, first, 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. Then, by deep reactive ion etching, 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. Specifically, in 409, 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. In 410, 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.

In the photoelectric sensor 200 shown in FIG. 5, 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.

Optionally, before preparing the transparent insulating layer, that is, before the above-mentioned 406, the method 400 further includes:

Specifically, first, 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. Then, 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. Specifically, in 406, on the structure shown in FIG. 13p, through deposition and photolithography processes, 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. And after follow-up 407-410, the photoelectric sensor as shown in FIG. 6 is prepared.

Optionally, 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.

Optionally, 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.

In the photoelectric sensor 200 shown in FIG. 6, 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. As shown in FIG. 14, the manufacturing method 500 of the photoelectric sensor includes:

501. Prepare a bottom gate in a first area on the surface of a substrate, and prepare a first metal layer in a second area on the surface of the substrate.

502. Prepare a transparent first insulating layer on the substrate, the bottom gate and the first metal layer.

503. Prepare a channel layer on the first insulating layer, where the channel layer is located above the bottom gate.

504. Prepare a first conductive layer 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 into The source electrode and the drain electrode, and the first conductive layer extends above the first metal layer.

505: Prepare a photodiode on the first conductive layer located above the first metal layer.

506. Prepare a reflection structure on the photodiode, so that the incident light is reflected when it passes through the photodiode and reaches the reflection structure, and returns to the photodiode.

Optionally, the reflective structure is prepared on the photodiode near the outer wall along the height direction of the photodiode.

Optionally, the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.

Optionally, the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.

507. Prepare a light-transmitting insulating layer on the first insulating layer, the first conductive layer, the reflective structure, and the photodiode.

508. Prepare a trench structure on the transparent insulating layer to expose the photodiode.

509. Prepare 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.

510. Prepare a light-shielding metal layer on the transparent insulating layer.

511. Prepare a light-transmitting insulating protective layer on the light-shielding metal layer and the contact electrode.

Specifically, the photoelectric sensor manufacturing method 500 can manufacture the photoelectric sensor as shown in FIG. 4.

In the photoelectric sensor 200 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. In the photodiode 210 region, 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.

It should be understood that 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.

It should be understood that the specific examples in the embodiments of the present application are only to help those skilled in the art to better understand the embodiments of the present application, rather than limiting the scope of the embodiments of the present application.

A person of ordinary skill in the art may realize that the preferred embodiments of the present application are described in detail above with reference to the accompanying drawings. However, the present application is not limited to the specific details in the foregoing embodiments. Within the scope of the technical concept of the present application, the present application The technical solution of, has undergone many simple modifications, and these simple modifications all fall within the protection scope of this application.

In addition, it should be noted that the various specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application provides various possible combinations. The combination method will not be explained separately.

In addition, the various implementations of this application can also be combined arbitrarily, as long as they do not violate the idea of this application, they should also be regarded as the content applied for in this application. It should be understood that the terms used in the embodiments of the present application and the appended claims are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. For example, the singular forms of "a", "above" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

The above are only specific implementations of this application, but the protection scope of this application is not limited to this. Anyone familiar with the technical field can easily think of various equivalents within the technical scope disclosed in this application. Modifications or replacements, these modifications or replacements shall be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

A photoelectric sensor, characterized by comprising: a photodiode and a reflective structure,

Wherein, 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 according to claim 1, wherein the reflective structure is arranged outside or inside the photodiode along the height direction of the photodiode.
The photoelectric sensor according to claim 1 or 2, wherein if the reflective structure is provided on the outside of the photodiode, a first light-transmitting structure is provided between the reflective structure and the outer wall of the photodiode. The thickness of the first light-transmitting medium layer enables the photodiode and the reflective structure to satisfy the optical resonance condition for the incident light.
The photoelectric sensor according to claim 3, wherein the reflective structure is continuously or discretely distributed around the photodiode.
The photoelectric sensor according to claim 1 or 2, wherein 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 photoelectric sensor according to claim 5, wherein the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.
The photoelectric sensor according to claim 1, wherein the reflective structure is arranged below the photodiode in a horizontal direction of the photodiode.
The photoelectric sensor according to claim 1 or 7, wherein if the reflective structure is provided below the photodiode, a second transparent structure is provided between the reflective structure and the lower surface of the photodiode. The optical medium layer, and the thickness of the second light-transmitting medium layer is such that the optical resonance condition for the incident light is satisfied between the photodiode and the reflective structure.
8. The photoelectric sensor according to claim 8, wherein the reflective structure is also used to block light from entering the photodiode from below the photodiode.
The photoelectric sensor according to claim 8 or 9, wherein the lower electrode of the photodiode is located between the photodiode and the reflective structure, and the lower electrode of the photodiode is located on the Below the peripheral area to allow the incident light to reach the reflective structure after passing through the photodiode.
11. The photoelectric sensor according to claim 10, wherein the photoelectric sensor further comprises a thin film transistor, and the thin film transistor and the photodiode constitute a pixel unit of the photoelectric sensor.
The photosensor of claim 11, wherein the thin film transistor comprises:

Grid,

A first insulating layer formed of a light-transmitting insulating material covering the gate,

A channel layer located on the first insulating layer,

A first conductive layer located on the channel layer, the first conductive layer has a gap exposing the channel layer to separate the first conductive layer into a source electrode and a drain electrode,

Wherein, 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 photoelectric sensor according to claim 12, wherein 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 photoelectric sensor according to any one of claims 1 to 6, wherein the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.
The photoelectric sensor according to any one of claims 7 to 13, wherein the reflective material of the reflective structure is metal.
The photoelectric sensor according to any one of claims 1 to 15, wherein the incident light is near infrared light.
A preparation method of a photoelectric sensor, characterized in that it comprises:

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;

Preparing a trench structure on the transparent insulating layer to expose 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;

Preparing a reflective structure located on the outer side of the photodiode 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;

Preparing a light-shielding metal layer on the transparent insulating layer and the reflective structure;

A transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode.
The method according to claim 17, wherein the preparing a reflective structure located on the outer side of the photodiode on the transparent insulating layer comprises:

The reflective structure is prepared on the light-transmitting insulating layer along the height direction of the photodiode.
The method according to claim 17 or 18, wherein the thickness of the transparent insulating layer between the reflective structure and the outer wall of the photodiode is such that the thickness between the photodiode and the reflective structure Meet the optical resonance conditions.
The method according to any one of claims 17 to 19, wherein the reflective structure is continuously or discretely distributed around the photodiode.
The method according to any one of claims 17 to 20, wherein the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.
A preparation method of a photoelectric sensor, characterized in that it comprises:

Preparing a bottom gate in a first area on the surface of the substrate, and preparing a first metal layer in a second area on the surface of the substrate;

Preparing a transparent first insulating layer on the substrate, the bottom gate and the first metal layer;

Preparing a channel layer on the first insulating layer, the channel layer being located above the bottom gate;

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;

Preparing a photodiode on the first insulating layer and the first conductive layer located above the first metal layer;

Preparing a light-transmitting insulating layer on the first insulating layer, the first conductive layer and the photodiode;

Preparing a trench structure on the transparent insulating layer to expose 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;

Preparing a light-shielding metal layer on the transparent insulating layer;

A transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode.
22. The method of claim 22, wherein the thickness of the first insulating layer located between the first metal layer and the lower surface of the photodiode is such that the photodiode and the first metal The optical resonance conditions are satisfied between the layers.
The method according to claim 22 or 23, wherein, before preparing the light-shielding metal layer, the method further comprises:

Preparing a reflective structure located on the outer side of the photodiode 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;

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 method according to claim 24, wherein the preparing a reflective structure located outside the photodiode on the transparent insulating layer comprises:

The reflective structure is prepared on the light-transmitting insulating layer along the height direction of the photodiode.
The method of claim 24 or 25, wherein the thickness of the transparent insulating layer between the reflective structure and the outer wall of the photodiode is such that the thickness between the photodiode and the reflective structure Meet the optical resonance conditions.
The method according to any one of claims 24 to 26, wherein the reflective structure is continuously or discretely distributed around the photodiode.
The method according to claim 22 or 23, characterized in that, before preparing the transparent insulating layer, the method further comprises:

Preparing a reflective structure on the photodiode, so that the incident light is reflected when it reaches the reflective structure through the photodiode and returns to the photodiode;

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 method according to claim 28, wherein the preparing a reflective structure on the photodiode comprises:

The reflection structure is prepared on the photodiode near the outer wall along the height direction of the photodiode.
The method according to claim 29, wherein the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.
The method according to any one of claims 22 to 30, wherein the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.
A preparation method of a photoelectric sensor, characterized in that it comprises:

Preparing a bottom gate in a first area on the surface of the substrate, and preparing a first metal layer in a second area on the surface of the substrate;

Preparing a transparent first insulating layer on the substrate, the bottom gate and the first metal layer;

Preparing a channel layer on the first insulating layer, the channel layer being located above the bottom gate;

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;

Preparing a photodiode on the first conductive layer located above the first metal layer;

Preparing a reflective structure on the photodiode, so that the incident light is reflected when it reaches the reflective structure through the photodiode and returns to the photodiode;

Preparing a light-transmitting insulating layer on the first insulating layer, the first conductive layer, the reflective structure and the photodiode;

Preparing a trench structure on the transparent insulating layer to expose 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;

Preparing a light-shielding metal layer on the transparent insulating layer;

A transparent insulating protective layer is prepared on the light-shielding metal layer and the contact electrode.
The method according to claim 32, wherein the preparing a reflective structure on the photodiode comprises:

The reflection structure is prepared on the photodiode near the outer wall along the height direction of the photodiode.
The method of claim 33, wherein the reflective structure is continuously or discretely distributed in a region close to the outer wall of the photodiode.
The method according to any one of claims 32 to 34, wherein the reflective material of the reflective structure is at least one of air, metal, silicon dioxide, and composite materials.