Light detection substrate and preparation method thereof, image sensor and electronic device

Abstract

The present disclosure provides a light detection substrate, comprising: a base substrate and a plurality of light sensing pixel structures located on the base substrate and arranged in an array, the light sensing pixel structure comprising: a signal reading circuit and a photoelectric conversion structure, the photoelectric conversion structure is located on a side of the signal reading circuit away from the base substrate and is electrically connected to the light sensing pixel structure, a first planarization layer is arranged between the signal reading circuit and the photoelectric conversion structure, and the first planarization layer is doped with hydrogen absorbing microparticles. The present disclosure also provides a method for preparing a light detection substrate, an image sensor, and an electronic device.

Description

Technical Field

[0001] The present invention relates to the field of light detection, and in particular to a light detection substrate and a preparation method thereof, an image sensor and an electronic device. Background Art

[0002] The Active Pixel Sensor (APS) is characterized by combining a thin-film transistor with a photodiode to form a pixel unit. Compared with the traditional Passive Pixel Sensor (PPS), APS has the advantages of low noise and high reading speed. APS has been widely used in glass-based image sensors.

[0003] In the APS structure, the working state of the thin film transistor directly affects the reading of the electrical signal, so the stability of the thin film transistor is particularly important. However, in actual applications, it is found that the active layer in the thin film transistor is easily affected by water, oxygen, and hydrogen, resulting in poor stability; especially hydrogen. Hydrogen penetration will cause the semiconductor material in the active layer to become conductive, causing the electrical properties of the thin film transistor to change. In the APS preparation process, the deposition process of the photodiode will produce a large number of hydrogen-related particles. When these hydrogen-related particles penetrate into the active layer in the thin film transistor, the electrical properties of the active layer will change, such as the threshold voltage of the thin film transistor will drift severely, thereby affecting the overall performance of the APS. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a light detection substrate and a preparation method thereof, an image sensor and an electronic device.

[0005] In a first aspect, an embodiment of the present disclosure provides a light detection substrate, comprising: a base substrate and a plurality of light sensing pixel structures located on the base substrate and arranged in an array, the light sensing pixel structure comprising: a signal reading circuit and a photoelectric conversion structure, the photoelectric conversion structure is located on a side of the signal reading circuit away from the base substrate and is electrically connected to the light sensing pixel structure, a first planarization layer is arranged between the signal reading circuit and the photoelectric conversion structure, and the first planarization layer is doped with hydrogen absorbing microparticles.

[0006] In some embodiments, the material of the hydrogen absorbing microparticles includes: metal oxides and / or metals.

[0007] In some embodiments, when the material of the hydrogen absorbing microparticles includes the metal oxide, the metal oxide includes: at least one of titanium dioxide, magnesium oxide, and aluminum oxide;

[0008] When the material of the hydrogen absorbing microparticles includes a metal, the metal includes at least one of nickel, palladium and platinum.

[0009] In some embodiments, the signal reading circuit includes: at least one thin film transistor;

[0010] The thin film transistor comprises: a gate and an active layer pattern, wherein the gate is located on a side of the active layer pattern close to the substrate or on a side of the active layer pattern away from the substrate;

[0011] The active layer pattern includes: a first sub-pattern and a second sub-pattern stacked together, the first sub-pattern is located on a side of the second sub-pattern close to the gate, and the oxygen vacancy concentration in the first sub-pattern is greater than the oxygen vacancy concentration in the second sub-pattern.

[0012] In some embodiments, the first sub-pattern and the second sub-pattern are made of the same material.

[0013] In some embodiments, a first passivation layer is disposed between the signal reading circuit and the first planarization layer;

[0014] And / or, a second passivation layer is provided between the first planarization layer and the photoelectric conversion structure;

[0015] And / or, a second planarization layer is provided on a side of the photoelectric conversion structure away from the base substrate, a third passivation layer is provided on a side of the second planarization layer facing away from the base substrate, a bias supply electrode is provided on a side of the third passivation layer facing away from the base substrate, and the bias supply electrode is electrically connected to the photoelectric conversion structure;

[0016] And / or, a shielding electrode is disposed on a side of the photoelectric conversion structure away from the substrate.

[0017] In a second aspect, an embodiment of the present disclosure further provides an image sensor, comprising: the light detection substrate provided in the first aspect.

[0018] In a third aspect, an embodiment of the present disclosure further provides an electronic device, including: an image sensor as provided in the second aspect.

[0019] In a fourth aspect, the present disclosure also provides a method for preparing the light detection substrate as provided in the first aspect, comprising:

[0020] forming a plurality of signal reading circuits arranged in an array on a substrate;

[0021] Forming a first planarization layer on a side of the signal reading circuit away from the base substrate, wherein the first planarization layer is doped with hydrogen absorbing microparticles;

[0022] A plurality of photoelectric conversion structures corresponding to the signal reading circuits are formed on a side of the first planarization layer away from the base substrate, and the photoelectric conversion structures are electrically connected to the corresponding signal reading circuits.

[0023] In some embodiments, the step of forming a first planarization layer on a side of the signal reading circuit away from the substrate includes:

[0024] The hydrogen absorbing microparticles are uniformly dispersed in the planarization material polymer to obtain a polymer-nano composite precursor solution;

[0025] The polymer-nano composite precursor liquid is formed on one side of the signal reading circuit, and is dried and film-formed to obtain a first planarization layer.

[0026] In some embodiments, the step of forming a plurality of signal reading circuits arranged in an array on a substrate includes: forming a thin film transistor;

[0027] The step of forming the thin film transistor comprises: forming a gate electrode and an active layer pattern respectively;

[0028] The gate is located on a side of the active layer pattern close to the base substrate or on a side of the active layer pattern away from the base substrate, and the active layer pattern includes: a first sub-pattern and a second sub-pattern stacked together, the first sub-pattern is located on a side of the second sub-pattern close to the gate, and the oxygen vacancy concentration in the first sub-pattern is greater than the oxygen vacancy concentration in the second sub-pattern.

[0029] In some embodiments, the gate is located on a side of the active layer pattern close to the substrate, and the steps of forming the gate and the active layer pattern respectively include:

[0030] forming the gate;

[0031] forming a gate insulating layer on a side of the gate away from the substrate;

[0032] forming a first semiconductor material film and a second semiconductor material film in sequence on a side of the gate insulating layer away from the substrate by a sputtering deposition process, wherein the first semiconductor material film and the second semiconductor material film are made of the same material, and the oxygen vacancy concentration in the first semiconductor material film is greater than the oxygen vacancy concentration in the second semiconductor material film;

[0033] Using a single patterning process to sequentially pattern the second semiconductor material film and the first semiconductor material film to obtain the second sub-pattern and the first sub-pattern respectively;

[0034] Alternatively, the gate is located on a side of the active layer pattern away from the substrate, and the steps of forming the gate and the active layer pattern respectively include:

[0035] forming a second semiconductor material film and a first semiconductor material film on the substrate in sequence by a sputtering deposition process, wherein the first semiconductor material film and the second semiconductor material film are made of the same material, and the oxygen vacancy concentration in the first semiconductor material film is greater than the oxygen vacancy concentration in the second semiconductor material film;

[0036] The first semiconductor material film and the second semiconductor material film are patterned sequentially by a single patterning process to obtain the first sub-pattern and the second sub-pattern respectively;

[0037] forming a gate insulating layer on a side of the first sub-pattern away from the base substrate;

[0038] A gate is formed on a side of the gate insulating layer away from the base substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic top view of a light detection substrate in an embodiment of the present disclosure;

[0040] Figure 2 A schematic cross-sectional view of a local position on a light detection substrate in an embodiment of the present disclosure;

[0041] Figure 3 A schematic diagram of a photoelectric conversion structure in an embodiment of the present disclosure;

[0042] Figure 4 A schematic diagram of a circuit structure of a light-sensing pixel structure in an embodiment of the present disclosure;

[0043] Figure 5 A schematic diagram of a circuit structure of a light-sensing pixel structure in an embodiment of the present disclosure;

[0044] Figure 6 A schematic cross-sectional view of a thin film transistor in a signal reading circuit in an embodiment of the present disclosure;

[0045] Figure 7 Another cross-sectional schematic diagram of a thin film transistor in a signal reading circuit in an embodiment of the present disclosure;

[0046] Figure 8 is another cross-sectional schematic diagram of a local position on the light detection substrate in an embodiment of the present disclosure;

[0047] Fig. 9 A flow chart of a method for preparing a light detection substrate provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solution of the present invention, a light detection substrate and a preparation method thereof, an image sensor and an electronic device provided by the present invention are described in detail below with reference to the accompanying drawings.

[0049] Figure 1 is a schematic top view of a light detection substrate in an embodiment of the present disclosure, Figure 2 FIG. 1 is a cross-sectional schematic diagram of a local position on the light detection substrate in the embodiment of the present disclosure. Figure 1 to Figure 2 As shown, the light detection substrate includes: a base substrate 1 and a plurality of light sensing pixel structures 2 located on the base substrate 1 and arranged in an array, a corresponding gate line Gate is configured for each row of light sensing pixel structures 2, and a corresponding signal reading line RL is configured for each column of light sensing pixel structures 2, and each light sensing pixel structure 2 is electrically connected to the corresponding gate line Gate and the signal reading line RL.

[0050] The light-sensing pixel structure 2 includes: a signal reading circuit 3 and a photoelectric conversion structure 4. The photoelectric conversion structure 4 is located on a side of the signal reading circuit 3 away from the substrate 1 and is electrically connected to the light-sensing pixel structure 2. A first planarization layer 5 is arranged between the signal reading circuit 3 and the photoelectric conversion structure 4. The first planarization layer 5 is doped with hydrogen-absorbing microparticles 6.

[0051] The photoelectric conversion structure 4 is a structure with a photoelectric conversion function. The photoelectric conversion structure 4 is configured to generate a corresponding electrical signal according to the collected incident light, and send the electrical signal to the signal reading circuit 3 for reading by the signal reading circuit 3. The signal reading circuit 3 includes at least one thin film transistor (TFT for short). The signal reading circuit 3 can be used to read the electrical signal output by the photoelectric conversion structure 4 for processing by an external image processor; generally, the thin film transistor includes: a gate 7, an active layer pattern 8, a source 9a and a drain 9b. The structure of the photoelectric conversion structure 4 and the signal reading circuit 3 in the present disclosure will be described in detail later in conjunction with specific examples.

[0052] In the embodiment of the present disclosure, the hydrogen absorbing microparticles 6 refer to microparticles that have an absorbing effect on hydrogen-related particles (hydrogen gas and hydrogen ions); wherein the microparticles refer to particles with a particle size less than 10000 nanometers. Further optionally, the microparticles are nanoparticles, and the particle size of the nanoparticles is less than 100 nanometers.

[0053] In the embodiment of the present disclosure, since the first planarization layer 5 is doped with hydrogen absorbing microparticles 6, the first planarization layer 5 has the function of absorbing hydrogen-related particles while having the planarization function. In the actual production process, the signal reading circuit 3 and the first planarization layer 5 are first formed in sequence, wherein the first planarization layer 5 completely covers the signal reading circuit 3; and then the photoelectric conversion structure 4 is formed on the side of the first planarization layer 5 away from the base substrate 1. In the process of forming the photoelectric conversion structure 4, although a large number of hydrogen-related particles will be generated, since the signal reading circuit 3 is completely covered by the first planarization layer 5 and the first planarization layer 5 is doped with hydrogen absorbing microparticles 6, the hydrogen absorbing microparticles 6 in the first planarization layer 5 will absorb the hydrogen-related particles that penetrate into the signal reading circuit 3, which can effectively prevent the hydrogen-related particles from penetrating into the signal reading circuit 3, thereby ensuring the stability of the electrical characteristics of the thin film transistor in the signal reading circuit 3.

[0054] In some embodiments, the material of the hydrogen absorbing microparticles 6 includes metal oxides and / or metals that have an absorbing effect on hydrogen-related particles. When the material of the hydrogen absorbing microparticles 6 includes metal oxides, the metal oxides include at least one of titanium dioxide, magnesium oxide, and aluminum oxide; when the material of the hydrogen absorbing microparticles 6 includes metals, the metals include at least one of nickel, palladium, and platinum.

[0055] Metal oxides such as titanium dioxide, magnesium oxide and aluminum oxide can react with hydrogen-related particles to produce redox reactions, thereby absorbing hydrogen-related particles. In addition, metal oxides such as titanium dioxide, magnesium oxide and aluminum oxide also have the property of absorbing water, so they can absorb water vapor that penetrates into the first planarization layer 5 to prevent water vapor from further penetrating into the signal reading circuit 3. Metals such as nickel, palladium and platinum can absorb hydrogen. Specifically, after hydrogen is absorbed by metals such as nickel, palladium and platinum, hydrogen molecules break into two hydrogen atoms, and hydrogen atoms are inserted into the gaps between metal atoms (it can be considered that a compound with no fixed ratio of metal and hydrogen is formed, and it can also be considered that hydrogen molecules break into more active hydrogen atoms under the action of metals). Of course, the material of the hydrogen-absorbing microparticles 6 in the present disclosure is not limited to the above materials, but any material that can absorb hydrogen-related particles and can exist in the form of microparticles (particle size less than 10000nm) can be applied to the present disclosure.

[0056] Figure 3 FIG. 4 is a schematic diagram of a structure of a photoelectric conversion structure 4 in an embodiment of the present disclosure. Figure 3 As shown, as a specific embodiment, the photoelectric conversion structure 4 includes: a first electrode 401 , a photoelectric conversion layer and a second electrode 403 which are sequentially arranged in a direction away from the base substrate 1 .

[0057] In some embodiments, the photoelectric conversion structure 4 includes: a PIN photodiode and a PN photosensitive diode, and the working state of the optical sensor can be controlled by controlling the voltage applied to the first electrode 401 and the second electrode 403. Among them, the photoelectric conversion layer may include a stacked P-type semiconductor layer (for example, a P-type Si layer) and an N-type semiconductor layer (for example, an N-type Si layer), in which case the photoelectric conversion structure 4 is a PN photodiode. The photoelectric conversion layer may also include a stacked P-type semiconductor layer, an intrinsic semiconductor layer (for example, an intrinsic Si layer) and an N-type semiconductor layer, in which case the photoelectric conversion structure 4 is a PIN photodiode. For example, the intrinsic semiconductor layer is a-Si material, the P-type semiconductor layer is a-Si doped with B ions, and the N-type semiconductor layer is a-Si doped with P ions.

[0058] In some embodiments, the second electrode 403 is a transparent electrode, and a transparent metal oxide material such as indium tin oxide, indium zinc oxide, gallium zinc oxide, etc. can be used. The first electrode 401 is a metal electrode, and a metal material or alloy material such as copper, aluminum, titanium, molybdenum, etc. can be used. It should be noted that in the embodiments of the present disclosure, "transparent" of a structure means that the structure can transmit light, rather than that the light transmittance of the structure is 100%.

[0059] Figure 4 FIG. 2 is a schematic diagram of a circuit structure of a light-sensing pixel structure 2 in an embodiment of the present disclosure. Figure 4 As shown, the signal reading circuit 3 includes a thin film transistor M0, a gate 7 of the thin film transistor M0 is connected to the gate line Gate of the corresponding row, a source 9a of the thin film transistor M0 is connected to the photoelectric conversion structure 4, and a second electrode 403 of the thin film transistor M0 is connected to the signal reading line RL of the corresponding column.

[0060] Figure 5 FIG. 2 is a schematic diagram of a circuit structure of a light-sensing pixel structure 2 in an embodiment of the present disclosure. Figure 5 As shown, the signal reading circuit 3 includes three thin film transistors: a reset transistor Mrst, a source follower transistor Msf and a selection transistor Msel; wherein the gate 7 of the reset transistor Mrst is connected to the reset signal line Reset, the source 9a of the reset transistor Mrst is connected to the reset voltage terminal (providing the reset voltage Vrst), the drain 9b of the reset transistor Mrst is connected to the gate 7 of the source follower transistor Msf, the gate 7 of the source follower transistor Msf is connected to the photoelectric conversion structure 4, the source 9a of the source follower transistor Msf is connected to the working voltage terminal (providing the working voltage Vdd), the drain 9b of the source follower transistor Msf is connected to the source 9a of the selection transistor Msel, the gate 7 of the selection transistor Msel is connected to the corresponding row gate line Gate, and the drain 9b of the selection transistor Msel is connected to the signal reading line RL of the corresponding column.

[0061] It should be noted that the above Figure 4 and Figure 5 The specific circuit structure of the signal reading circuit 3 in the light sensing pixel structure 2 shown in the figure is only for illustrative purposes and does not limit the technical solution of the present disclosure. In the embodiment of the present disclosure, the signal reading circuit 3 can also adopt other circuit structures, which will not be listed one by one here.

[0062] Figure 6 is a cross-sectional schematic diagram of a thin film transistor in the signal reading circuit 3 in the embodiment of the present disclosure, Figure 7 FIG. 2 is another cross-sectional schematic diagram of a thin film transistor in the signal reading circuit 3 in the embodiment of the present disclosure. Figure 6 and Figure 7 As shown, the thin film transistor includes a gate 7, an active layer pattern 8, a source electrode 9a and a drain electrode 9b, wherein a gate insulating layer 18 is disposed between the gate 7 and the gate insulating layer 18. In the present disclosure, the active layer pattern 8 includes a first sub-pattern 801 and a second sub-pattern 802 which are stacked, wherein the first sub-pattern 801 is located on a side of the second sub-pattern 802 close to the gate 7, and the oxygen vacancy concentration in the first sub-pattern 801 is greater than the oxygen vacancy concentration in the second sub-pattern 802.

[0063] In some embodiments, the material of the active layer pattern 8 is a metal oxide semiconductor, such as indium gallium zinc oxide (IGZO).

[0064] Figure 6 The bottom-gate thin film transistor is shown in FIG. 8 , that is, the gate electrode 7 is located on the side of the active layer pattern 8 close to the base substrate 1 , and the first sub-pattern 801 is located below the second sub-pattern 802 . Figure 7 The figure shows a top-gate thin film transistor, that is, the gate 7 is located on the side of the active layer pattern 8 away from the base substrate 1, and the first sub-pattern 801 is located above the second sub-pattern 802.

[0065] The transmission path of the on-state current of the thin film transistor is located at the interface between the active layer pattern 8 and the gate insulating layer 18, that is, the part of the active layer pattern 8 close to the gate insulating layer 18; in the embodiment of the present disclosure, by setting the oxygen vacancy concentration in the first sub-pattern 801 close to the gate insulating layer 18 in the active layer pattern 8 to be relatively large (that is, the concentration of free carriers is relatively large), the conductivity of the first sub-pattern 801 can be effectively improved, thereby increasing the on-state current of the TFT device; at the same time, the main transmission path of the off-state leakage current of the thin film transistor is located in the second sub-pattern 802 far away from the gate insulating layer 18 in the active layer pattern 8. In the embodiment of the present disclosure, by setting the oxygen vacancy concentration in the second sub-pattern 802 to be relatively small (that is, the concentration of free carriers is relatively small), defects are reduced, and the conductivity of the second sub-pattern 802 can be effectively reduced, thereby reducing the off-state leakage current to improve the stability of the device.

[0066] It should be noted that when the signal reading circuit 3 includes multiple thin film transistors, the active layer pattern 8 in one of the thin film transistors adopts the stacked structure of the first sub-pattern 801 and the second sub-pattern 802, which can improve the working stability of the entire signal reading circuit 3 to a certain extent. Figure 5 The stability of the internal source follower transistor Msf will greatly affect the stability of the entire signal reading circuit 3, so only the active layer pattern 8 in the source follower transistor Msf can adopt the stacked structure of the first sub-pattern 801 and the second sub-pattern 802, while the active layer patterns 8 in the reset transistor Mrst and the selection transistor Msel can adopt conventional designs. Of course, the active layer patterns 8 in all thin film transistors in the signal reading circuit 3 can also adopt the stacked structure of the first sub-pattern 801 and the second sub-pattern 802.

[0067] In some embodiments, the material of the first sub-pattern 801 is the same as that of the second sub-pattern 802. In this case, the first semiconductor material film used to prepare the first sub-pattern 801 and the second semiconductor material film used to prepare the second sub-pattern 802 can be deposited continuously (only the process environment during the deposition process needs to be adjusted), without opening the chamber and replacing the target material, and no additional process is generated.

[0068] As a specific example, the case where the first sub-pattern 801 is located below the second sub-pattern 802 is taken as an example. First, a preset semiconductor material is deposited by a sputtering deposition process in an oxygen-poor environment or a pure argon environment to obtain a first semiconductor material film; then, a certain amount of oxygen is introduced into the process chamber, and a preset semiconductor material is deposited by a sputtering deposition process in an oxygen-rich environment to obtain a second semiconductor material film, at which time the oxygen vacancy concentration in the first semiconductor material film is greater than the oxygen vacancy concentration in the second semiconductor material film; then, the first semiconductor material film and the second semiconductor material film are patterned (generally including photoresist coating, exposure, development, film etching, photoresist stripping and other processes) to obtain a first sub-pattern 801 and a second sub-pattern 802 having a phase pattern. At this time, the first sub-pattern 801 and the second sub-pattern 802 are made of the same material, and the oxygen vacancy concentration in the first sub-pattern 801 is greater than the oxygen vacancy concentration in the second sub-pattern 802.

[0069] Figure 8 FIG. 2 is another cross-sectional schematic diagram of a local position on the light detection substrate in the embodiment of the present disclosure. Figure 8 As shown, Figure 8 FIG. 4 shows a thin film transistor T connected to the photoelectric conversion structure 4 in the signal reading circuit 3. The thin film transistor T can be Figure 4 The thin film transistor M0 in the embodiment may also be Figure 5 In addition, Figure 8 The photoelectric conversion structure 4 shown in FIG. 4 is a PIN photodiode.

[0070] In some embodiments, a first passivation layer 10 is arranged between the signal reading circuit 3 and the first planarization layer 5; the first passivation layer 10 can play a certain protective role for the signal reading circuit 3 to prevent metal structures such as the source 9a and the drain 9b from being oxidized during the subsequent preparation of the first planarization layer 5 and to block the intrusion of water vapor.

[0071] In some embodiments, a second passivation layer 11 is disposed between the first planarization layer 5 and the photoelectric conversion structure 4 ; the second passivation layer 11 can increase the bonding strength between the first electrode 401 formed subsequently and the first planarization layer 5 .

[0072] In some embodiments, a second planarization layer 13 is disposed on a side of the photoelectric conversion structure 4 away from the base substrate 1, a third passivation layer 14 is disposed on a side of the second planarization layer 13 facing away from the base substrate 1, a bias supply electrode 15 is disposed on a side of the third passivation layer 14 facing away from the base substrate 1, and the bias supply electrode 15 is electrically connected to the photoelectric conversion structure 4. The bias supply electrode 15 is used to provide a bias voltage to the second electrode 403 to control the operation of the photoelectric conversion structure 4; the material of the bias supply electrode 15 can be transparent metal oxide materials such as indium tin oxide, indium zinc oxide, and gallium zinc oxide.

[0073] In some implementations, an encapsulation layer 12 is directly provided between the second planarization layer 13 and the photoelectric conversion structure 4. The encapsulation layer 12 can play a certain protective role on the photoelectric conversion structure 4, so as to block the intrusion of water vapor during the subsequent preparation of the first planarization layer 5, and reduce the side wall leakage inside the photoelectric conversion structure 4 (PIN photodiode).

[0074] In some embodiments, a shielding electrode 17 is disposed on the side of the photoelectric conversion structure 4 away from the substrate 1, and the shielding electrode 17 can effectively shield the external electric field from interfering with the electrical structure on the light detection substrate. A fourth passivation layer 16 is disposed between the shielding electrode 17 and the bias supply electrode 15 to insulate the bias supply electrode 15 from the shielding electrode 17.

[0075] Based on the same inventive concept, the disclosed embodiment further provides a method for preparing a light detection substrate, which can be used to prepare the light detection substrate in the previous embodiment.

[0076] Fig. 9 Flow chart of a method for preparing a light detection substrate provided by an embodiment of the present disclosure. Fig. 9 As shown, the preparation method comprises:

[0077] Step S1, forming a plurality of signal reading circuits arranged in an array on a base substrate.

[0078] Wherein, the signal reading circuit includes at least one thin film transistor. Step S1 includes: a step of forming a thin film transistor. The step of forming the thin film transistor includes: a step of forming a gate and an active layer pattern respectively, wherein the gate is located on a side of the active layer pattern close to the substrate or on a side of the active layer pattern away from the substrate, and the active layer pattern includes: a first sub-pattern and a second sub-pattern arranged in a stacked manner, the first sub-pattern is located on a side of the second sub-pattern close to the gate, and the oxygen vacancy concentration in the first sub-pattern is greater than the oxygen vacancy concentration in the second sub-pattern.

[0079] In some embodiments, see Figure 6 As shown in , the gate is located on the side of the active layer pattern close to the substrate. At this time, the steps of forming the gate and the active layer pattern respectively include: first, forming the gate; then, forming a gate insulating layer on the side of the gate away from the substrate; then, forming a first semiconductor material film and a second semiconductor material film in sequence on the side of the gate insulating layer away from the substrate by a sputtering deposition process, the first semiconductor material film and the second semiconductor material film are made of the same material, and the oxygen vacancy concentration in the first semiconductor material film is greater than the oxygen vacancy concentration in the second semiconductor material film; then, patterning the second semiconductor material film and the first semiconductor material film in sequence by a one-time patterning process to obtain a second sub-pattern and a first sub-pattern respectively.

[0080] In other embodiments, see Figure 7 As shown in , the gate is located on the side of the active layer pattern away from the substrate. At this time, the steps of forming the gate and the active layer pattern respectively include: first, forming a second semiconductor material film and a first semiconductor material film on the substrate in sequence by a sputtering deposition process, the first semiconductor material film and the second semiconductor material film are made of the same material, and the oxygen vacancy concentration in the first semiconductor material film is greater than the oxygen vacancy concentration in the second semiconductor material film; patterning the first semiconductor material film and the second semiconductor material film in sequence by a one-time patterning process to obtain a first sub-pattern and a second sub-pattern respectively; forming a gate insulating layer on the side of the first sub-pattern away from the substrate; and forming a gate on the side of the gate insulating layer away from the substrate.

[0081] In the above two cases, the deposition of the first semiconductor material film is carried out in an oxygen-poor environment or a pure argon environment, and the deposition of the second semiconductor material film is carried out in an oxygen-rich environment. The first semiconductor material film and the second semiconductor material film are prepared continuously, without opening the chamber and replacing the target material in the middle, and no additional process is generated.

[0082] Step S2, forming a first planarization layer on a side of the signal reading circuit away from the base substrate, wherein the first planarization layer is doped with hydrogen absorbing microparticles.

[0083] In some embodiments, first, hydrogen absorbing microparticles are evenly dispersed in a planarizing material polymer by ultrasound, vibration, etc. to obtain a polymer-nano composite precursor liquid, wherein the planarizing material polymer serves as a matrix, and hydrogen absorbing nanoparticles (related materials and particle sizes can be found in the previous content) serve as reinforcements, and the planarizing material polymer includes polymers with a carbon-carbon double-chain structure such as methyl methacrylate, vinyl chloride or styrene; then, the polymer-nano composite precursor liquid is formed on one side of the signal reading circuit, and a drying film-forming process is performed to obtain a first planarizing layer.

[0084] Step S3, forming a plurality of photoelectric conversion structures corresponding to the signal reading circuits on a side of the first planarization layer away from the base substrate, wherein the photoelectric conversion structures are electrically connected to the corresponding signal reading circuits.

[0085] In step S3 , a first electrode, a photoelectric conversion layer and a second electrode may be sequentially prepared on the first planarization layer.

[0086] In some embodiments, when preparing Figure 8 When the light detection substrate is shown in , the step of forming a first passivation layer is included between step S1 and step S2, the step of forming a second passivation layer is included between step S2 and step S3, and after step S3, the steps of forming an encapsulation layer, forming a third passivation layer, forming a bias supply electrode, forming a fourth passivation layer and forming a shielding electrode are also included.

[0087] certainly, Figure 8 At least one of the first passivation layer, the second passivation layer, the encapsulation layer, the third passivation layer, the bias supply electrode, the fourth passivation layer and the shielding electrode shown in the figure can be selectively removed, and the corresponding preparation steps can also be selectively removed.

[0088] Based on the same inventive concept, an embodiment of the present disclosure further provides an image sensor, which includes the light detection substrate provided in the above embodiment. The specific description of the light detection substrate can be found in the previous description of this document, and will not be repeated here.

[0089] In addition to the light detection substrate, the image sensor may also include peripheral circuits such as row drive circuits, column drive circuits, amplifier circuits, preprocessing circuits, etc. These circuits are conventional structures in the art, and the specific circuit structures and working processes are not described in detail herein.

[0090] Based on the same inventive concept, an embodiment of the present disclosure further provides an electronic device, which includes an image sensor. The image sensor adopts the above-mentioned image sensor. The electronic device may be a digital camera, a mobile phone, a tablet computer, a laptop computer, etc.

[0091] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A light detection substrate, characterized in that: include: A base substrate and a plurality of light-sensing pixel structures located on the base substrate and arranged in an array, the light-sensing pixel structures comprising: a signal reading circuit and a photoelectric conversion structure, the photoelectric conversion structure being located on a side of the signal reading circuit away from the base substrate and being electrically connected to the signal reading circuit, a first planarization layer being arranged between the signal reading circuit and the photoelectric conversion structure, the first planarization layer having a connecting via extending through the thickness direction thereof, the photoelectric conversion structure being electrically connected to the signal reading circuit through a switching electrode extending through the connecting via, and a side wall of the connecting via being in direct contact with the switching electrode; the orthographic projection of the first planarization layer on the base substrate is completely covered, and the orthographic projection of the signal reading circuit on the base substrate, except for the orthographic projection of a portion of the surface connected to the switching electrode on the base substrate, is the remaining orthographic projection; The main material of the first planarization layer is a polymer with a carbon-carbon double-chain structure; the first planarization layer is doped with hydrogen absorbing microparticles; the materials of the hydrogen absorbing microparticles include: metal oxides and metals; A second planarization layer is arranged on a side of the photoelectric conversion structure away from the substrate; an encapsulation layer is arranged between the second planarization layer and the photoelectric conversion structure; and the encapsulation layer wraps the side wall of the photoelectric conversion structure and the surface away from the substrate.

2. The light detection substrate according to claim 1, characterized in that When the material of the hydrogen absorbing microparticles includes the metal oxide, the metal oxide includes at least one of titanium dioxide, magnesium oxide, and aluminum oxide; When the material of the hydrogen absorbing microparticles includes a metal, the metal includes at least one of nickel, palladium and platinum.

3. The light detection substrate according to claim 1 or 2, characterized in that: The signal reading circuit includes: at least one thin film transistor; The thin film transistor comprises: a gate and an active layer pattern, wherein the gate is located on a side of the active layer pattern close to the substrate or on a side of the active layer pattern away from the substrate; The active layer pattern includes: a first sub-pattern and a second sub-pattern stacked together, the first sub-pattern is located on a side of the second sub-pattern close to the gate, and the oxygen vacancy concentration in the first sub-pattern is greater than the oxygen vacancy concentration in the second sub-pattern.

4. The light detection substrate according to claim 3, characterized in that The first sub-pattern and the second sub-pattern are made of the same material.

5. The light detection substrate according to claim 1, characterized in that A first passivation layer is disposed between the signal reading circuit and the first planarization layer; And / or, a second passivation layer is provided between the first planarization layer and the photoelectric conversion structure; And / or, a third passivation layer is provided on a side of the second planarization layer facing away from the base substrate, a bias supply electrode is provided on a side of the third passivation layer facing away from the base substrate, and the bias supply electrode is electrically connected to the photoelectric conversion structure; And / or, a shielding electrode is disposed on a side of the photoelectric conversion structure away from the substrate.

6. An image sensor, characterized in that: include: A light detection substrate as described in any one of claims 1 to 5.

7. An electronic device, characterized in that: include: The image sensor as claimed in claim 6.

8. A method for preparing a light detection substrate as claimed in any one of claims 1 to 5, characterized in that: include: forming a plurality of signal reading circuits arranged in an array on a substrate; forming a first planarization layer on a side of the signal reading circuit away from the substrate; The step of forming a first planarization layer on a side of the signal reading circuit away from the base substrate comprises: uniformly dispersing hydrogen absorbing microparticles in a planarization material polymer to obtain a polymer-nano composite precursor liquid; forming the polymer-nano composite precursor liquid on one side of the signal reading circuit, and performing a drying film forming process to obtain a first planarization layer; A plurality of photoelectric conversion structures corresponding to the signal reading circuits are formed on a side of the first planarization layer away from the base substrate, wherein the photoelectric conversion structures are electrically connected to the corresponding signal reading circuits; Forming an encapsulation layer on a side of the photoelectric conversion structure away from the substrate; forming a second planarization layer on a side of the encapsulation layer away from the substrate; The first planarization layer has a connection via that runs through the thickness direction thereof, and the photoelectric conversion structure is electrically connected to the signal reading circuit through a switching electrode that runs through the connection via, and the side wall of the connection via is in direct contact with the switching electrode; the first planarization layer completely covers the orthographic projection of the signal reading circuit on the base substrate, except for the orthographic projection of the partial surface connected to the switching electrode on the base substrate.

9. The method for preparing a light detection substrate according to claim 8, characterized in that: The light detection substrate is the light detection substrate as claimed in claim 3, and the step of forming a plurality of signal reading circuits arranged in an array on the base substrate comprises: forming a thin film transistor; The step of forming the thin film transistor comprises: forming a gate electrode and an active layer pattern respectively; The gate is located on a side of the active layer pattern close to the base substrate or on a side of the active layer pattern away from the base substrate, and the active layer pattern includes: a first sub-pattern and a second sub-pattern stacked together, the first sub-pattern is located on a side of the second sub-pattern close to the gate, and the oxygen vacancy concentration in the first sub-pattern is greater than the oxygen vacancy concentration in the second sub-pattern.

10. The method for preparing a light detection substrate according to claim 9, characterized in that: The gate is located on a side of the active layer pattern close to the base substrate, and the steps of forming the gate and the active layer pattern respectively include: forming the gate; forming a gate insulating layer on a side of the gate away from the substrate; forming a first semiconductor material film and a second semiconductor material film in sequence on a side of the gate insulating layer away from the substrate by a sputtering deposition process, wherein the first semiconductor material film and the second semiconductor material film are made of the same material, and the oxygen vacancy concentration in the first semiconductor material film is greater than the oxygen vacancy concentration in the second semiconductor material film; Using a single patterning process to sequentially pattern the second semiconductor material film and the first semiconductor material film to obtain the second sub-pattern and the first sub-pattern respectively; Alternatively, the gate is located on a side of the active layer pattern away from the substrate, and the steps of forming the gate and the active layer pattern respectively include: forming a second semiconductor material film and a first semiconductor material film on the substrate in sequence by a sputtering deposition process, wherein the first semiconductor material film and the second semiconductor material film are made of the same material, and the oxygen vacancy concentration in the first semiconductor material film is greater than the oxygen vacancy concentration in the second semiconductor material film; The first semiconductor material film and the second semiconductor material film are patterned sequentially by a single patterning process to obtain the first sub-pattern and the second sub-pattern respectively; forming a gate insulating layer on a side of the first sub-pattern away from the base substrate; A gate is formed on a side of the gate insulating layer away from the base substrate.

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