CN112670303B - Optical sensor, preparation method thereof and display panel - Google Patents

Optical sensor, preparation method thereof and display panel Download PDF

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CN112670303B
CN112670303B CN202011549326.1A CN202011549326A CN112670303B CN 112670303 B CN112670303 B CN 112670303B CN 202011549326 A CN202011549326 A CN 202011549326A CN 112670303 B CN112670303 B CN 112670303B
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tft
sensing
active layer
layer
electrode
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CN112670303A (en
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蔡广烁
郭力
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TCL Huaxing Photoelectric Technology Co Ltd
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TCL Huaxing Photoelectric Technology Co Ltd
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Abstract

The invention provides a light sensor and a manufacturing method thereof and a display panel, wherein the light sensor comprises a plurality of light sensor matrix units, each light sensor matrix unit comprises a sensing TFT, an amplifying TFT, a switching TFT and a storage capacitor, wherein an active layer of the sensing TFT is amorphous silicon, an active layer of the amplifying TFT is an oxide semiconductor, the sensing TFT is connected with the amplifying TFT, the amplifying TFT is connected with the switching TFT, the switching TFT controls the sensing TFT to detect and read an electric signal amplified by the amplifying TFT, and when the sensing TFT is in an on state, the electric signal is transmitted to a signal reading circuit. By adopting the 3T1C architecture as the light sensor matrix unit, the traditional 2T1C architecture is replaced, the detection of weak light by the light sensor can be realized, the light response of the light sensor is effectively improved, and the light sensor has high light response and high signal to noise ratio; the preparation of the sensing TFT and the amplifying TFT shares a plurality of yellow light processes, so that the cost is reduced, and the advantage of high uniformity of a-Si large area can be fully exerted.

Description

Optical sensor, preparation method thereof and display panel
Technical Field
The invention relates to the technical field of display, in particular to a light sensor, a preparation method thereof and a display panel.
Background
Along with the rapid development of display panels on electronic products such as mobile phones, televisions, tablet computers and intelligent watches, pursuits of people on intelligent display are also higher and higher, and an integrated optical sensor is hopeful to realize a novel intelligent display screen integrating multiple functions by virtue of the application of the integrated optical sensor in the fields of remote optical interaction, gesture sensing, ambient light sensing, personal identification and the like.
Optical sensors based on amorphous silicon (a-Si) thin film transistors (Thin Film Transistor, TFT) have received great attention because of their advantages of mature process, high large area uniformity, low cost, high responsivity, high signal to noise ratio, small size, etc. Referring to FIG. 1, a conventional photo sensor matrix unit of a-Si TFT adopts a 2T1C architecture, and is generally composed of a sensor TFT (sensor TFT) and a storage capacitor C st And a switch TFT (switch TFT), the active layer of the sensing TFT is amorphous silicon (a-Si), and when the light sensor matrix unit adopts the structure, the signal size of the reading end (Readout) of the switching TFT depends on the light response of the a-Si TFT, which limits the detection of weak light and the signal to noise ratio of the light sensor。
In view of the foregoing, it is desirable to provide a new optical sensor, a manufacturing method thereof, and a display panel for solving the above-mentioned problems.
Disclosure of Invention
The optical sensor, the preparation method thereof and the display panel solve the technical problems that when the 2T1C framework is adopted as an optical sensor matrix unit in the existing optical sensor, the signal size of a reading end of a switching TFT depends on the optical response of an a-Si TFT, so that the detection of weak light and the signal to noise ratio of the optical sensor are limited.
In order to solve the problems, the technical scheme provided by the invention is as follows:
an embodiment of the present invention provides a photosensor, including:
a sensing substrate;
the cover plate is arranged opposite to the induction substrate at intervals;
the light sensor matrix units are arranged on the sensing substrate and are positioned between the sensing substrate and the cover plate, the light sensor matrix units comprise a sensing TFT, an amplifying TFT, a switching TFT and a storage capacitor, the sensing TFT comprises a first active layer, the amplifying TFT comprises a second active layer, the switching TFT comprises a third active layer, the material of the first active layer is amorphous silicon, and the material of the second active layer is oxide semiconductor;
the sensing TFT is connected with the amplifying TFT, the amplifying TFT is connected with the switching TFT, the sensing TFT is used for converting detected optical signals into electric signals, the storage capacitor is used for storing charges according to the electric signals in the sensing TFT, and the switching TFT controls the electric signals detected by the sensing TFT and amplified by the amplifying TFT to be transmitted to the signal reading circuit.
According to an embodiment of the present invention, the plurality of light sensor matrix units include:
the first grid electrode, the second grid electrode and the third grid electrode are arranged on the sensing substrate;
a gate insulating layer covering the first gate electrode, the second gate electrode, and the third gate electrode;
the first active layer, the second active layer and the third active layer are arranged on the grid insulation layer, the first active layer is arranged corresponding to the first grid, the second active layer is arranged corresponding to the second grid, and the third active layer is arranged corresponding to the third grid;
an ohmic contact layer disposed on the first, second, and third active layers;
the first source electrode and the first drain electrode, the second source electrode and the second drain electrode, and the third source electrode and the third drain electrode are arranged on the ohmic contact layer;
the sensing TFT comprises the first grid electrode, the first source electrode and the first drain electrode, the amplifying TFT comprises the second grid electrode, the second source electrode and the second drain electrode, and the switching TFT comprises the third grid electrode, the third source electrode and the third drain electrode.
According to the photosensor provided by the embodiment of the invention, the first source electrode is connected with the second grid electrode, and the second source electrode is connected with the third drain electrode.
According to the optical sensor provided by the embodiment of the invention, the optical sensor further comprises a protective layer covering the induction TFT, the amplifying TFT and the switching TFT, a first contact hole and a second contact hole are formed in the protective layer and the gate insulating layer, a conductive layer is arranged in the first contact hole and the second contact hole, and the first source electrode is connected with the second gate electrode through the conductive layer in the first contact hole and the second contact hole.
According to the optical sensor provided by the embodiment of the invention, the material of the second active layer is any one of IZO, in2O3, IGZO and ZnO.
According to the optical sensor provided by the embodiment of the invention, the cover plate is provided with the shading layer at one side close to the sensing substrate, and the shading layer is arranged corresponding to the amplifying TFT and the switching TFT.
According to the light sensor provided by the embodiment of the invention, the light shielding layer is made of one or more of metal, metal oxide, black matrix resin and other organic materials.
The embodiment of the invention provides a preparation method of a light sensor, which comprises the following steps:
s10: providing a sensing substrate, and forming a first grid electrode, a second grid electrode and a third grid electrode on the sensing substrate through a yellow light process;
s20: forming a gate insulating layer on the sensing substrate, wherein the gate insulating layer covers the first gate electrode, the second gate electrode and the third gate electrode;
s30: forming a first active layer, a second active layer and a third active layer on the gate insulating layer through a yellow light process respectively, wherein the first active layer is arranged corresponding to the first gate, the second active layer is arranged corresponding to the second gate, and the third active layer is arranged corresponding to the third gate;
s40: forming an ohmic contact layer on the first active layer, the second active layer and the third active layer through a yellow light process;
s50: forming a first source electrode, a first drain electrode, a second source electrode, a second drain electrode, a third source electrode and a third drain electrode on the ohmic contact layer through a yellow light process, so as to form a sensing TFT, an amplifying TFT and a switching TFT, wherein the sensing TFT, the amplifying TFT and the switching TFT form a light sensor matrix unit;
s60: forming a protective layer covering the sensing TFT, the amplifying TFT and the switching TFT;
s70: forming a first contact hole and a second contact hole on the protective layer and the gate insulating layer, forming a conductive layer in the first contact hole and the second contact hole, and connecting the first source electrode with the second gate electrode through the conductive layer in the first contact hole and the second contact hole;
s80: providing a cover plate, and forming a shading layer on one side of the cover plate, which is close to the sensing substrate, wherein the shading layer is arranged corresponding to the amplifying TFT and the switching TFT; and
s90: and covering the induction substrate and the cover plate with each other.
According to the manufacturing method of the optical sensor provided by the embodiment of the invention, the material of the first active layer is amorphous silicon, and the material of the second active layer is an oxide semiconductor.
The embodiment of the invention provides a display panel which comprises the light sensor.
The beneficial effects of the invention are as follows: the invention provides a photosensor and a preparation method thereof and a display panel, wherein the photosensor replaces the traditional 2T1C architecture by adopting a 3T1C architecture photosensor matrix unit, the photosensor matrix unit comprises a sensing TFT, an amplifying TFT, a switching TFT and a storage capacitor, wherein a first active layer of the sensing TFT is amorphous silicon, a second active layer of the amplifying TFT is oxide semiconductor, the switching TFT is used for controlling the sensing TFT to detect and read an electric signal amplified by the amplifying TFT, and when the sensing TFT is in an on state, the electric signal is transmitted to a signal reading circuit, on one hand, the detection of weak light by the photosensor can be realized, the optical response of the photosensor is effectively improved, and the photosensor has high optical response and high signal-to-noise ratio; on the other hand, the preparation of the sensing TFT and the amplifying TFT shares a plurality of yellow light processes, so that the cost is reduced, the advantage of high uniformity of a-Si large area can be fully exerted, and the application of a large-area optical sensor is facilitated.
Drawings
In order to more clearly illustrate the embodiments or the technical solutions in the prior art, the following description will briefly introduce the drawings that are needed in the embodiments or the description of the prior art, it is obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a prior art photosensor using a 2T1C architecture as a photosensor matrix unit;
FIG. 2 is a schematic cross-sectional view of a photosensor according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of a photosensor using a 3T1C architecture as a photosensor matrix unit according to an embodiment of the present invention;
fig. 4 is a flowchart of a method for manufacturing a photosensor according to an embodiment of the present invention;
fig. 4A to fig. 4I are schematic flow structure diagrams of a preparation method of an optical sensor according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments refers to the accompanying drawings, which illustrate specific embodiments in which the invention may be practiced. The directional terms mentioned in the present invention, such as [ upper ], [ lower ], [ front ], [ rear ], [ left ], [ right ], [ inner ], [ outer ], [ side ], etc., are only referring to the directions of the attached drawings. Accordingly, directional terminology is used to describe and understand the invention and is not limiting of the invention. In the drawings, like elements are designated by like reference numerals.
When the invention adopts a 2T1C framework aiming at the light sensor matrix unit of the display panel in the prior art, the signal size of the reading end of the switch TFT depends on the light response of the a-Si TFT, so that the detection of weak light and the signal to noise ratio of the light sensor are limited, and the embodiment can solve the defect.
Referring to fig. 2, the optical sensor provided by the embodiment of the present invention includes a sensing substrate 1 and a cover plate 5 disposed at opposite intervals, wherein a plurality of optical sensor matrix units are disposed on the sensing substrate 1, and each optical sensor matrix unit includes a sensor TFT (Sensor TFT), an amplifier TFT (Magnify TFT), a switch TFT30 and a storage capacitor C st When light is incident on the sensing TFT10 from the outside, the sensing TFT10 can convert the detected light signal into an electrical signal, which is a photocurrent, thereby allowing a current to flow, the storage capacitor C st For storing charge according to the electric signal in the sensing TFT10, the switching TFT30 controls reading of the electric signal detected by the sensing TFT10 and amplified by the amplifying TFT20, when it is in an on stateThe electrical signal is passed to a signal reading circuit (not shown).
Embodiments of the present invention regulate the storage capacitor C by sensing changes in photocurrent in the TFT10 st Thereby adjusting the voltage of the amplifying TFT20 and further changing the magnitude of the current input to the induction driving circuit, wherein the amplifying effect of the amplifying TFT20 on the electric signal is mainly determined by the magnitude of the transconductance, which is the ratio between the variation value of the current at the output end and the variation value of the voltage at the input end.
Since the transconductance of the oxide semiconductor TFT represented by IGZO is much larger than that of a conventional a-Si TFT, in the embodiment of the present invention, the sensing TFT10 includes the first active layer 12, the amplifying TFT20 includes the second active layer 22, the switching TFT30 includes the third active layer 32, and the material of the first active layer 12 is amorphous silicon, which can exert the advantages of large light absorption coefficient and high photoelectric conversion efficiency of amorphous silicon in the entire wavelength range, and high uniformity of large area, so as to be beneficial to realizing the application of the large-area optical sensor; the material of the second active layer 22 is an oxide semiconductor, specifically, the material of the second active layer 22 may be any one of IZO, in2O3, IGZO, and ZnO, which can amplify the weak light detected by the sensing TFT10, thereby effectively improving the optical response of the optical sensor, and having high optical response and high signal-to-noise ratio, and the material of the third active layer 32 is not limited In the embodiment of the present invention.
Specifically, the light sensor matrix unit includes:
the first gate 11, the second gate 21 and the third gate 31 are disposed on the array substrate 1;
a gate insulating layer 2 covering the first gate electrode 11, the second gate electrode 21, and the third gate electrode 31;
the first active layer 12, the second active layer 22, and the third active layer 32 are disposed on the gate insulating layer 2, the first active layer 12 is disposed corresponding to the first gate 11, the second active layer 22 is disposed corresponding to the second gate 21, and the third active layer 32 is disposed corresponding to the third gate 31;
an ohmic contact layer disposed on the first, second, and third active layers 12, 22, and 32, the ohmic contact layer including a first portion 13 disposed on the first active layer 12, a second portion 23 disposed on the second active layer 22, and a third portion 33 disposed on the third active layer 32;
the first source 14 and the first drain 15, the second source 24 and the second drain 25, and the third source 34 and the third drain 35 are disposed on the ohmic contact layer.
Specifically, the sensing TFT10 includes the first gate electrode 11, the first source electrode 14, and the first drain electrode 15, the amplifying TFT20 includes the second gate electrode 21, the second source electrode 24, and the second drain electrode 25, and the switching TFT30 includes the third gate electrode 31, the third source electrode 34, and the third drain electrode 35, wherein the first source electrode 14 is connected to the second gate electrode 21, and the second source electrode 24 is connected to the third drain electrode 35.
The light sensor further includes a protective layer 3, the protective layer 3 covering the sensing TFT10, the amplifying TFT20, and the switching TFT30.
In the embodiment of the present invention, a first contact hole 16 and a second contact hole 26 are disposed on the protection layer 3 and the gate insulating layer 2, the first source electrode 14 is connected to the second gate electrode 21 through the first contact hole 16 and the second contact hole 26, similarly, a third contact hole 27 and a fourth contact hole 36 are also disposed on the protection layer 3, the second source electrode 24 is connected to the third drain electrode 35 through the third contact hole 27 and the fourth contact hole 36, the conductive layer 4 is disposed in the first contact hole 16 and the second contact hole 26, and the conductive layer 4 is also disposed in the third contact hole 27 and the fourth contact hole 36. Specifically, the material of the conductive layer 4 includes Indium Tin Oxide (ITO), mo\cu, mo\al, al, mo\ti\cu, mo\ti\al, moti\cu, moti\al, and a plurality of conductive oxides or metals or metal stacks thereof.
Further, in order to make the external light only irradiate onto the sensing TFT10, a light shielding layer 6 is disposed on a side of the cover 5 close to the sensing substrate 1, the light shielding layer 6 is disposed corresponding to the amplifying TFT20 and the switching TFT30, and the material of the light shielding layer 6 may be one or more of metal, metal oxide, and black matrix resin.
When the light sensor Matrix unit is located in the display area of the display panel, the light shielding layer 6 may be a Black Matrix (BM) layer disposed on the color film substrate 5.
Referring to fig. 2 together with fig. 3, fig. 3 is a schematic circuit diagram of a photosensor using a 3T1C architecture as a photosensor matrix unit according to an embodiment of the present invention, where the 3T1C architecture includes the sensing TFT10, the amplifying TFT20, the switching TFT30 and the storage capacitor C st The sensing TFT10 includes a first gate 11, a first source 14, and a first drain 15, the first gate 11 is connected to the sensing scan line Vg, and the first drain 15 is connected to the sensing voltage signal V D-sen Connecting; the amplifying TFT20 includes a second gate 21, a second source 24, and a second drain 25, the second gate 21 is connected to the first source 14, and the second drain 25 is connected to the amplified voltage signal V mag Connecting; the switching TFT30 includes a third Gate electrode 31, a third source electrode 34, and a third drain electrode 35, wherein the third Gate electrode 31 is connected to a switching scan line Gate (n), the third source electrode 34 is connected to a signal reading circuit Readout, the third source electrode 34 is connected to the sensing driving circuit, and the third drain electrode 35 is connected to the second source electrode 24; the storage capacitor C st Comprises a first electrode and a second electrode, wherein the first electrode is connected with the first source electrode 14 and the second grid electrode 21, and the second electrode is connected with the induction scanning line Vg.
It can be understood that, first, when external light irradiates onto the sensing TFT10, the level of the sensing scanning line Vg is low, at this time, the sensing TFT10 is turned off, the light changes the off-state current of the TFT10, the sensing voltage signal VD-sen drives the sensing TFT10 to convert the external light signal into an electrical signal, and generate a photocurrent corresponding to the light, the storage capacitor Cst stores charges, converts the current signal into a voltage signal, changes the voltage of the second gate of the amplifying TFT20, and amplifies the source leakage current of the amplifying TFT 20; after that, the level of the switching scan line Gate (n) is high, the switching TFT30 is turned on, the amplified current signal is transferred to the signal reading circuit Readout through the switching TFT30, and the photo sensor matrix unit thus realizes detection of weak light.
Specifically, the induction driving circuit is used for converting an optical signal output by the signal reading circuit Readout into a data signal, and applying a predetermined coordinate algorithm to generate coordinate data corresponding to an input through the optical sensor, thereby acquiring position information corresponding to the optical signal, wherein the coordinate data can be used as a touch input or a pointer input.
The induction scanning line Vg can provide a constant voltage signal and also can provide an alternating voltage signal; the induced voltage signal V D-sen And the amplified voltage signal V mag Driving voltages are respectively supplied to the sensing TFT10 and the amplifying TFT 20.
When the photosensor is applied to the display panel, the photosensor may be integrated in a display area of the display panel, at this time, the sensing scan line Vg and the switching scan line Gate (n) may be wirings additionally disposed in a horizontal direction, the switching scan line Gate (n) may also be collinear with a scan line for driving to display a picture, which is located on the array substrate 1, and when the switching scan line Gate (n) is collinear with a scan line for driving to display a picture, the photosensor matrix unit operates in a display state. The sensing scan line Vg and the switching scan line Gate (n) may be integrated in a non-display area of the display panel, which is not limited in the present invention.
Referring to fig. 4, the method for manufacturing the optical sensor provided by the embodiment of the invention includes the following steps:
s10: a sensing substrate 1 is provided, and a first gate 11, a second gate 21 and a third gate 31 are formed on the sensing substrate 1 through a yellow light process.
Specifically, referring to fig. 4A, the material of the sensing substrate 1 includes glass, polyethylene naphthalate (polyethylene naphthalate), polyethylene terephthalate (PET), polyimide, etc.; the materials of the first gate 11, the second gate 21 and the third gate 31 include Indium Tin Oxide (ITO), mo/Cu, mo/Al, mo/Ti/Cu, mo/Ti/Al, moTi/Cu, moTi/Al, and other conductive oxides or metals or metal stacks.
The first gate 11, the second gate 21 and the third gate 31 are formed in the same process flow, so that the manufacturing steps of the photosensor can be simplified and the cost can be reduced.
S20: a gate insulating layer 2 is formed on the sensing substrate 1, and the gate insulating layer 2 covers the first gate electrode 11, the second gate electrode 21, and the third gate electrode 31.
Specifically, referring to fig. 4B, the material of the gate insulating layer 2 includes aluminum oxide, silicon nitride, silicon dioxide, aluminum nitride, zirconium oxide, and the like.
S30: the first active layer 12, the second active layer 22 and the third active layer 32 are formed on the gate insulating layer 2 through a yellow light process, respectively.
Specifically, referring to fig. 4C, first, a semiconductor layer may be formed on the gate insulating layer 2 by a coating or chemical vapor deposition process, and then the first active layer 12, the second active layer 22 and the third active layer 32 are formed by a yellow light process, wherein the first active layer 12 is disposed corresponding to the first gate 11, the second active layer 22 is disposed corresponding to the second gate 21, and the third active layer 32 is disposed corresponding to the third gate 31.
The material of the first active layer 12 is amorphous silicon, the material of the second active layer 22 is an oxide semiconductor, specifically, the material of the second active layer 22 may be any one of IZO, in2O3, IGZO and ZnO, and the material of the third active layer 32 is not limited In this embodiment.
Also, the first active layer 12, the second active layer 22, and the third active layer 32 are formed in the same process flow, so that the manufacturing steps of the display panel can be simplified and the cost can be reduced.
S40: an ohmic contact layer is formed on the first, second and third active layers 12, 22 and 32 through a yellow light process.
Specifically, referring to fig. 4D, the ohmic contact layer includes a first portion 13 formed on the first active layer 12, a second portion 23 formed on the second active layer 22, and a third portion 33 formed on the third active layer 32.
S50: the first source and drain electrodes 14 and 15, the second source and drain electrodes 24 and 25, and the third source and drain electrodes 34 and 35 are formed on the ohmic contact layer through a yellow light process, thereby forming the sensing TFT10, the amplifying TFT20, and the switching TFT30, and the sensing TFT10, the amplifying TFT20, and the switching TFT30 constitute a light sensor matrix cell.
Specifically, referring to fig. 4E, the first source electrode 14 and the first drain electrode 15 are connected to the first active layer 12 through the ohmic contact layer, the second source electrode 24 and the second drain electrode 25 are connected to the second active layer 22 through the ohmic contact layer, and the third source electrode 34 and the third drain electrode 35 are connected to the third active layer 32 through the ohmic contact layer.
The materials of the first source 14 and the first drain 15, the second source 24 and the second drain 25, and the third source 34 and the third drain 35 include various conductive oxides or metals or metal stacks such as Indium Tin Oxide (ITO), mo/Cu, mo/Al, mo/Ti/Cu, mo/Ti/Al, moTi/Cu, moTi/Al, and the like.
S60: a protective layer 3 is formed to cover the sensing TFT10, the amplifying TFT20, and the switching TFT30.
Specifically, referring to fig. 4F, a protective layer 3 may be grown on the sensing TFT10, the amplifying TFT20 and the switching TFT30 by any one of coating, chemical vapor deposition, atomic layer deposition and physical vapor deposition, wherein the protective layer 3 is a transparent insulating material, and the materials of the protective layer 3 include aluminum oxide, silicon nitride, silicon dioxide, aluminum nitride, zirconium oxide and the like.
S70: a first contact hole 16 and a second contact hole 26 are formed on the protective layer 3 and the gate insulating layer 2, a conductive layer 4 is formed in the first contact hole 16 and the second contact hole 26, and the first source 14 is connected to the second gate 21 through the conductive layer 4 in the first contact hole 16 and the second contact hole 26.
Specifically, referring to fig. 4G, the first contact hole 16 and the second contact hole 26 are covered with a conductive layer 4, the first source electrode 14 is connected to the second gate electrode 21 through the conductive layer 4, and the material of the conductive layer 4 includes Indium Tin Oxide (ITO), mo\cu, mo\al, al, mo\ti\cu, mo\ti\al, moti\cu, moti\al, or a plurality of conductive oxides or metals or metal stacks such as moti\al, and the like.
Similarly, a third contact hole 27 and a fourth contact hole 36 are further formed in the protective layer 3, the second source electrode 24 is connected to the third drain electrode 35 through the third contact hole 27 and the fourth contact hole 36, and the conductive layer 4 also covers the third contact hole 27 and the fourth contact hole 36.
S80: a cover plate 5 is provided, a light shielding layer 6 is formed on one side of the cover plate 5 near the sensing substrate 1, and the light shielding layer 6 is disposed corresponding to the amplifying TFT20 and the switching TFT30.
Specifically, referring to fig. 4H, the material of the light shielding layer 6 may be one or more of metal, metal oxide, black matrix resin, and other organic materials.
S90: the induction substrate 1 and the cover plate 5 are mutually covered.
Specifically, please refer to fig. 4I.
The embodiment of the invention also provides a display panel, which comprises the light sensor in the embodiment, wherein the display panel can be a liquid crystal display panel or a light emitting diode display panel, the light sensor can be integrated in a display area of the display panel, and the light sensor matrix unit works in a display state.
The beneficial effects are as follows: the optical sensor provided by the embodiment of the invention adopts the 3T1C architecture optical sensor matrix unit to replace the traditional 2T1C architecture, the optical sensor matrix unit comprises a sensing TFT, an amplifying TFT, a switching TFT and a storage capacitor, wherein a first active layer of the sensing TFT is amorphous silicon, a second active layer of the amplifying TFT is an oxide semiconductor, the switching TFT is used for controlling the sensing TFT to detect and read an electric signal amplified by the amplifying TFT, and when the sensing TFT is in an on state, the electric signal is transmitted to a signal reading circuit, so that on one hand, the detection of weak light by the optical sensor can be realized, the optical response of the optical sensor is effectively improved, and the optical sensor has high optical response and high signal-to-noise ratio; on the other hand, the preparation of the sensing TFT and the amplifying TFT shares a plurality of yellow light processes, so that the cost is reduced, the advantage of high uniformity of a-Si large area can be fully exerted, and the application of a large-area optical sensor is facilitated.
In summary, although the present invention has been described in terms of the preferred embodiments, the preferred embodiments are not limited to the above embodiments, and various modifications and changes can be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention is defined by the appended claims.

Claims (10)

1. A light sensor, comprising:
a sensing substrate;
the cover plate is arranged opposite to the induction substrate at intervals;
the light sensor matrix units are arranged on the sensing substrate and are positioned between the sensing substrate and the cover plate, the light sensor matrix units comprise a sensing TFT, an amplifying TFT, a switching TFT and a storage capacitor, the sensing TFT comprises a first active layer, the amplifying TFT comprises a second active layer, the switching TFT comprises a third active layer, the first active layer is made of amorphous silicon, the second active layer is made of oxide semiconductor, and the transconductance of the amplifying TFT is larger than that of the sensing TFT;
the sensing TFT is connected with the amplifying TFT, the amplifying TFT is connected with the switching TFT, the sensing TFT is used for converting detected optical signals into electric signals, the storage capacitor is used for storing charges according to the electric signals in the sensing TFT, and the switching TFT controls the electric signals detected by the sensing TFT and amplified by the amplifying TFT to be transmitted to the signal reading circuit.
2. The light sensor of claim 1, wherein the plurality of light sensor matrix cells comprises:
the first grid electrode, the second grid electrode and the third grid electrode are arranged on the sensing substrate;
a gate insulating layer covering the first gate electrode, the second gate electrode, and the third gate electrode;
the first active layer, the second active layer and the third active layer are arranged on the grid insulation layer, the first active layer is arranged corresponding to the first grid, the second active layer is arranged corresponding to the second grid, and the third active layer is arranged corresponding to the third grid;
an ohmic contact layer disposed on the first, second, and third active layers;
the first source electrode, the first drain electrode, the second source electrode, the second drain electrode, the third source electrode and the third drain electrode are arranged on the ohmic contact layer;
the sensing TFT comprises the first grid electrode, the first source electrode and the first drain electrode, the amplifying TFT comprises the second grid electrode, the second source electrode and the second drain electrode, and the switching TFT comprises the third grid electrode, the third source electrode and the third drain electrode.
3. The photosensor of claim 2, wherein the first source is connected to the second gate and the second source is connected to the third drain.
4. A photosensor according to claim 3, further comprising a protective layer covering the sensing TFT, the amplifying TFT and the switching TFT, wherein first and second contact holes are provided in the protective layer and the gate insulating layer, wherein a conductive layer is provided in the first and second contact holes, and wherein the first source electrode is connected to the second gate electrode through the conductive layer in the first and second contact holes.
5. The light sensor according to claim 1, wherein a material of the second active layer is any one of IZO, in2O3, IGZO, and ZnO.
6. The photosensor according to claim 1, wherein a light shielding layer is disposed on a side of the cover plate adjacent to the sensing substrate, and the light shielding layer is disposed corresponding to the amplifying TFT and the switching TFT.
7. The light sensor of claim 6, wherein the light shielding layer is made of one or more of metal, metal oxide, and black matrix resin.
8. A method of manufacturing a light sensor, comprising the steps of:
s10: providing a sensing substrate, and forming a first grid electrode, a second grid electrode and a third grid electrode on the sensing substrate through a yellow light process;
s20: forming a gate insulating layer on the sensing substrate, wherein the gate insulating layer covers the first gate electrode, the second gate electrode and the third gate electrode;
s30: forming a first active layer, a second active layer and a third active layer on the gate insulating layer through a yellow light process respectively, wherein the first active layer is arranged corresponding to the first gate, the second active layer is arranged corresponding to the second gate, and the third active layer is arranged corresponding to the third gate;
s40: forming an ohmic contact layer on the first active layer, the second active layer and the third active layer through a yellow light process;
s50: forming a first source electrode, a first drain electrode, a second source electrode, a second drain electrode, a third source electrode and a third drain electrode on the ohmic contact layer through a yellow light process, so as to form a sensing TFT, an amplifying TFT and a switching TFT, wherein the sensing TFT, the amplifying TFT and the switching TFT form a light sensor matrix unit, and the transconductance of the amplifying TFT is larger than that of the sensing TFT;
s60: forming a protective layer covering the sensing TFT, the amplifying TFT and the switching TFT;
s70: forming a first contact hole and a second contact hole on the protective layer and the gate insulating layer, forming a conductive layer in the first contact hole and the second contact hole, and connecting the first source electrode with the second gate electrode through the conductive layer in the first contact hole and the second contact hole;
s80: providing a cover plate, and forming a shading layer on one side of the cover plate, which is close to the sensing substrate, wherein the shading layer is arranged corresponding to the amplifying TFT and the switching TFT; and
s90: and covering the induction substrate and the cover plate with each other.
9. The method of claim 8, wherein the material of the first active layer is amorphous silicon and the material of the second active layer is an oxide semiconductor.
10. A display panel comprising the light sensor of any one of claims 1-7.
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