CN112670303A - Optical sensor, preparation method thereof and display panel - Google Patents
Optical sensor, preparation method thereof and display panel Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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Abstract
The invention provides an optical sensor, a manufacturing method thereof and a display panel, wherein the optical sensor comprises a plurality of optical sensor matrix units, each optical sensor matrix unit comprises an induction TFT, an amplifying TFT, a switch TFT and a storage capacitor, wherein an active layer of the induction TFT is amorphous silicon, an active layer of the amplifying TFT is an oxide semiconductor, the induction TFT is connected with the amplifying TFT, the amplifying TFT is connected with the switch TFT, the switch TFT controls reading of an electric signal which is detected by the induction TFT and amplified by the amplifying TFT, and when the switch TFT is in an on state, the electric signal is transmitted to a signal reading circuit. By adopting the 3T1C framework as the optical sensor matrix unit to replace the traditional 2T1C framework, the detection of the optical sensor on weak light 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; the preparation of the induction TFT and the amplification TFT share 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
Technical Field
The invention relates to the technical field of display, in particular to an optical sensor, a preparation method of the optical sensor and a display panel.
Background
With the rapid development of display panels on electronic products such as mobile phones, televisions, tablet computers and intelligent watches, people pursue intelligent display more and more, and the integratable optical sensor is expected to realize a novel intelligent display screen integrating multiple functions by virtue of the application of the integratable optical sensor in the fields of remote optical interaction, gesture induction, ambient light induction, personal identification and the like.
A photosensor based on a Thin Film Transistor (TFT) has received much attention because it has advantages of mature process, high uniformity of large area, low cost, high responsivity, high signal-to-noise ratio, and small size. Referring to FIG. 1, a conventional a-Si TFT photosensor matrix cell is constructed with a 2T1C structure, typically including a sensing TFT (sensor TFT), a storage capacitor CstAnd a switch TFT (switch TFT), the active layer of the sensing TFT adopts amorphous silicon (a-Si), when the photosensor matrix unit adopts the structure, the signal size of the reading end (Readout) of the switch TFT depends on the optical response of the a-Si TFT, which limits the detection of weak light and the signal-to-noise ratio of the photosensor.
In summary, it is desirable to provide a new optical sensor, a method for manufacturing the same, and a display panel, so as to solve the above technical problems.
Disclosure of Invention
The optical sensor, the preparation method thereof and the display panel provided by the invention solve the technical problems that when a 2T1C framework is adopted as an optical sensor matrix unit in the existing optical sensor, the signal size of a switch TFT reading end 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 above problems, the technical scheme provided by the invention is as follows:
an embodiment of the present invention provides an optical sensor, including:
an induction substrate;
the cover plate is arranged opposite to the induction substrate at intervals;
the light sensor array comprises a plurality of light sensor array units, a sensing substrate and a cover plate, wherein the light sensor array units are arranged on the sensing substrate and are positioned between the sensing substrate and the cover plate, each light sensor array unit comprises 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, and the second active layer is made of an 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 a detected optical signal into an electric signal, the storage capacitor is used for storing charges according to the electric signal in the sensing TFT, and the switching TFT controls the electric signal which is detected by the sensing TFT and amplified by the amplifying TFT to be transmitted to a signal reading circuit.
According to the optical sensor provided by the embodiment of the present invention, the plurality of optical sensor matrix units include:
the first grid, the second grid and the third grid are arranged on the induction substrate;
a gate insulating layer covering the first gate, the second gate, and the third gate;
the first active layer, the second active layer and the third active layer are arranged on the gate insulating layer, 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;
an ohmic contact layer disposed on the first active layer, the second active layer, and the third active layer;
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;
wherein the sensing TFT includes the first gate electrode, the first source electrode, and the first drain electrode, the amplifying TFT includes the second gate electrode, the second source electrode, and the second drain electrode, and the switching TFT includes the third gate electrode, the third source electrode, and the third drain electrode.
According to the optical sensor provided by the embodiment of the present invention, the first source is connected to the second gate, and the second source is connected to the third drain.
According to the optical sensor provided by the embodiment of the invention, the optical sensor further comprises a protective layer covering the sensing 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, conductive layers are 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 layers in the first contact hole and the second contact hole.
According to the light 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, a light shielding layer is arranged on one side of the cover plate close to the induction substrate, and the light shielding layer is arranged corresponding to the amplifying TFT and the switching TFT.
According to the optical sensor provided by the embodiment of the invention, the material of the light shielding layer is one or more of metal, metal oxide, black matrix resin and other organic materials.
The embodiment of the invention provides a preparation method of an optical sensor, which comprises the following steps:
s10: providing an induction substrate, and forming a first grid electrode, a second grid electrode and a third grid electrode on the induction substrate through a yellow light process;
s20: forming a gate insulating layer on the sensing substrate, the gate insulating layer covering the first gate, the second gate, and the third gate;
s30: forming a first active layer, a second active layer and a third active layer on the gate insulating layer by a yellow light process, 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 by a yellow light process;
s50: forming a first source electrode and a first drain electrode, a second source electrode and a second drain electrode, and a third source electrode and a third drain electrode on the ohmic contact layer through a yellow light process, thereby forming an induction TFT, an amplification TFT and a switch TFT, wherein the induction TFT, the amplification TFT and the switch TFT form a photosensor 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 in 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 to 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 light shielding layer on one side of the cover plate close to the induction substrate, wherein the light shielding layer is arranged corresponding to the amplifying TFT and the switch TFT; and
s90: and covering the induction substrate and the cover plate mutually.
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 optical sensor.
The invention has the beneficial effects that: according to the optical sensor, the preparation method thereof and the display panel, the optical sensor replaces the traditional 2T1C framework by adopting a 3T1C framework optical sensor matrix unit, the optical sensor matrix unit comprises an induction TFT, an amplifying TFT, a switch TFT and a storage capacitor, wherein a first active layer of the induction TFT is amorphous silicon, a second active layer of the amplifying TFT is an oxide semiconductor, the switch TFT is used for controlling reading of an electric signal which is detected by the induction TFT and amplified by the amplifying TFT, and when the switch TFT is in an on state, the electric signal is transmitted to a signal reading circuit; on the other hand, the preparation of the induction TFT and the amplification TFT share 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 light sensor is facilitated.
Drawings
In order to illustrate the embodiments or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the invention, and it is obvious for a person skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic circuit diagram of a prior art optical sensor employing a 2T1C architecture as an optical sensor matrix unit;
fig. 2 is a schematic cross-sectional structure diagram of an optical sensor according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of an optical sensor adopting a 3T1C architecture as an optical sensor matrix unit according to an embodiment of the present invention;
fig. 4 is a flowchart of a method for manufacturing an optical sensor according to an embodiment of the present invention;
fig. 4A to 4I are schematic flow structure diagrams of a method for manufacturing an optical sensor according to an embodiment of the present invention.
Detailed Description
The following description of the various embodiments refers to the accompanying drawings that 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 ], are only referring to the directions of the attached drawings. Accordingly, the directional terms used are used for explanation and understanding of the present invention, and are not used for limiting the present invention. In the drawings, elements having similar structures are denoted by the same reference numerals.
The invention aims at solving the defect that when the optical sensor matrix unit of the display panel in the prior art adopts a 2T1C framework, the signal magnitude of the reading end of the switch TFT depends on the optical response of the a-Si TFT, so that the detection of weak light and the signal-to-noise ratio of the optical sensor are limited.
Referring to fig. 2, the optical sensor according to the embodiment of the present invention includes a sensing substrate 1 and a cover plate 5 disposed at an interval, wherein a plurality of optical sensor matrix units are disposed on the sensing substrate 1, and each of the optical sensor matrix units includes a sensing TFT (sensor TFT)10, an amplifying TFT (magnetic TFT)20, a switch TFT30(switch TFT), and a storage capacitor CstWhen light is incident on the sensing TFT10 from the outside, the sensing TFT10 can convert a detected light signal into an electrical signal, which is a photocurrent, thereby causing a current to flow, and the storage capacitor CstFor storing electric charges 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, and when it is in an on state, transfers the electric signal to a signal reading circuit (not shown in the figure).
The embodiment of the present invention adjusts the storage capacitor C by sensing the change in photocurrent in the TFT10stThe voltage of the amplifying TFT20 is adjusted, and the current input into the sensing driving circuit is changed, wherein the amplifying effect of the amplifying TFT20 on the electrical signal mainly depends on the transconductance thereof, which is the ratio between the variation value of the output end current and the variation value of the input end voltage.
Since the transconductance of the oxide semiconductor TFT represented by IGZO is much larger than that of the 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, so that the advantages of large light absorption coefficient and high photoelectric conversion efficiency of the amorphous silicon in the whole wavelength range, and high large-area uniformity are exerted, which is beneficial to the application of a large-area photosensor; the material of the second active layer 22 is an oxide semiconductor, and specifically, the material of the second active layer 22 may be any one of IZO, In2O3, IGZO, and ZnO, which can amplify weak light detected by the sensing TFT10, thereby effectively improving the optical response of the photosensor, and having high optical response and high signal-to-noise ratio, but the embodiment of the present invention is not limited to the material of the third active layer 32.
Specifically, the photosensor matrix unit includes:
the first grid 11, the second grid 21 and the third grid 31 are arranged 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 electrode 11, the second active layer 22 is disposed corresponding to the second gate electrode 21, and the third active layer 32 is disposed corresponding to the third gate electrode 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 electrode 14 and the first drain electrode 15, the second source electrode 24 and the second drain electrode 25, and the third source electrode 34 and the third drain electrode 35 are disposed on the ohmic contact layer.
Specifically, the sensing TFT10 includes the first gate 11, the first source 14, and the first drain 15, the amplifying TFT20 includes the second gate 21, the second source 24, and the second drain 25, and the switching TFT30 includes the third gate 31, the third source 34, and the third drain 35, wherein the first source 14 is connected to the second gate 21, and the second source 24 is connected to the third drain 35.
The photosensor further includes a protection layer 3, the protection layer 3 covering the sensing TFT10, the amplifying TFT20, and the switching TFT 30.
In the embodiment of the present invention, the protective layer 3 and the gate insulating layer 2 are provided with a first contact hole 16 and a second contact hole 26, 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, the protective layer 3 is provided with a third contact hole 27 and a fourth contact hole 36, 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, a conductive layer 4 is provided in the first contact hole 16 and the second contact hole 26, and the conductive layer 4 is also provided 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, Mo \ Ti \ Cu, Mo \ Ti \ Al, MoTi \ Cu, MoTi \ Al, and other conductive oxides or metals or metal stacks.
Further, in order to irradiate external light only onto the sensing TFT10, a light shielding layer 6 is disposed on the cover 5 on a side close to the sensing substrate 1, the light shielding layer 6 is disposed corresponding to the amplifying TFT20 and the switching TFT30, and the light shielding layer 6 may be made of one or more organic materials such as metal, metal oxide, and black matrix resin.
When the photosensor Matrix unit is located in a display region of a display panel, the light shielding layer 6 may be a Black Matrix (BM) layer disposed on the color film substrate 5.
Referring to fig. 3 in addition to fig. 2, fig. 3 is a circuit schematic diagram of a light sensor adopting a 3T1C structure as a light sensor matrix unit according to an embodiment of the present invention, where the 3T1C structure includes the sensing TFT10, the amplifying TFT20, the switching TFT30 and the storage capacitor CstThe sensing TFT10 includes a first gate 11, a first source 14 and a first drain 15, the first gate 11 is connected to a sensing scan line Vg, and the first drain 15 is connected to a sensing voltage signal VD-senConnecting; the amplifying TFT20 includesA second gate 21, a second source 24 and a second drain 25, the second gate 21 being connected to the first source 14, the second drain 25 being connected to the amplified voltage signal VmagConnecting; the switch TFT30 includes a third gate 31, a third source 34 and a third drain 35, the third gate 31 is connected to a switch scan line gate (n), the third source 34 is connected to a signal reading circuit Readout, the third source 34 is connected to the sensing driving circuit, and the third drain 35 is connected to the second source 24; the storage capacitor CstThe gate structure comprises a first electrode and a second electrode, wherein the first electrode is connected with the first source electrode 14 and the second gate electrode 21, and the second electrode is connected with the sensing scanning line Vg.
It can be understood that, first, when external light irradiates on the sensing TFT10, the level of the sensing scan line Vg is low, at this time, the sensing TFT10 is turned off, the off-state current of the TFT10 is changed by the light irradiation, the sensing voltage signal VD-sen drives the sensing TFT10 to convert the external light signal into an electrical signal, a photocurrent corresponding to the light irradiation is generated, the storage capacitor Cst stores charges, converts the current signal into a voltage signal, and changes the voltage of the second gate of the amplifying TFT20, and the voltage signal amplifies the source-drain current of the amplifying TFT 20; then, the level of the switch scanning line gate (n) is high, the switch TFT30 is turned on, the amplified current signal is transmitted to the signal reading circuit Readout through the switch TFT30, and the photosensor matrix unit thus realizes detection of weak light.
Specifically, the sensing driving circuit is configured to convert an optical signal output by the signal reading circuit Readout into a data signal, and apply a predetermined coordinate algorithm to generate coordinate data corresponding to an input through the optical sensor, so as to obtain position information corresponding to the optical signal, where the coordinate data may be used as a touch input or a pointer input.
The induction scanning line Vg can provide a constant voltage signal and can also provide an alternating voltage signal; the induced voltage signal VD-senAnd said amplified voltage signal VmagRespectively the sensing TFT10 and the amplifyingThe TFT20 supplies a driving voltage.
When the optical sensor is applied to a display panel, the optical sensor may be integrated in a display area of the display panel, at this time, the sensing scan line Vg and the switch scan line gate (n) may be traces additionally arranged along a horizontal direction, the switch scan line gate (n) may also be collinear with a scan line for driving to realize picture display on the array substrate 1, and when the switch scan line gate (n) is collinear with a scan line for driving picture display, the optical sensor matrix unit operates in a display state. The sensing scan line Vg and the switching scan line gate (n) may also be integrated in a non-display area of the display panel, which is not limited in the present invention.
Referring to fig. 4, a method for manufacturing an optical sensor according to an embodiment of the present invention includes the following steps:
s10: providing an induction substrate 1, and forming a first gate 11, a second gate 21 and a third gate 31 on the induction substrate 1 by 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, and the like; the materials of the first grid 11, the second grid 21 and the third grid 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 laminates.
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 optical sensor 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 by a photolithography process.
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 photolithography process, wherein the first active layer 12 corresponds to the first gate 11, the second active layer 22 corresponds to the second gate 21, and the third active layer 32 corresponds 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 the embodiments of the present invention.
Similarly, 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 preparation steps of the display panel can be simplified and the cost can be reduced.
S40: an ohmic contact layer is formed on the first active layer 12, the second active layer 22 and the third active layer 32 by a photolithography 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: forming a first source electrode 14 and a first drain electrode 15, a second source electrode 24 and a second drain electrode 25, and a third source electrode 34 and a third drain electrode 35 on the ohmic contact layer by a yellow light process, thereby forming an induction TFT10, an amplification TFT20, and a switching TFT30, wherein the induction TFT10, the amplification TFT20, and the switching TFT30 constitute a photosensor matrix unit.
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 electrode 14, the first drain electrode 15, the second source electrode 24, the second drain electrode 25, the third source electrode 34 and the third drain electrode 35 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.
S60: a protective layer 3 is formed covering the sensing TFT10, the amplifying TFT20, and the switching TFT 30.
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 material of the protective layer 3 includes 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 opened in 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 electrode 14 is connected to the second gate electrode 21 through the conductive layer 4 in the first contact hole 16 and the second contact hole 26.
Specifically, referring to fig. 4G, a conductive layer 4 covers the first contact hole 16 and the second contact hole 26, the first source electrode 14 is connected to the second gate electrode 21 through the conductive layer 4, and the conductive layer 4 is made of a plurality of conductive oxides, metals, or metal laminates, such as Indium Tin Oxide (ITO), Mo \ Cu, Mo \ Al, Mo \ Ti \ Cu, Mo \ Ti \ Al, MoTi \ Cu, and MoTi \ Al.
Similarly, a third contact hole 27 and a fourth contact hole 36 are also 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: providing a cover plate 5, forming a light shielding layer 6 on one side of the cover plate 5 close to the induction substrate 1, wherein the light shielding layer 6 is arranged corresponding to the amplifying TFT20 and the switch TFT 30.
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: and covering the induction substrate 1 and the cover plate 5 mutually.
Specifically, please refer to fig. 4I.
An embodiment of the present invention further provides a display panel, where the display panel includes the optical sensor in the foregoing embodiment, the display panel may be a liquid crystal display panel or a light emitting diode display panel, and the optical sensor may be integrated in a display area of the display panel, and at this time, the optical sensor matrix unit operates in a display state.
The beneficial effects are that: according to the optical sensor and the preparation method thereof, and the display panel, the optical sensor replaces the traditional 2T1C framework by adopting a 3T1C framework optical sensor matrix unit, the optical sensor matrix unit comprises an induction TFT, an amplifying TFT, a switch TFT and a storage capacitor, wherein a first active layer of the induction TFT is amorphous silicon, a second active layer of the amplifying TFT is an oxide semiconductor, the switch TFT is used for controlling reading of an electric signal which is detected by the induction TFT and amplified by the amplifying TFT, and when the switch TFT is in an on state, the electric signal is transmitted to a signal reading circuit; on the other hand, the preparation of the induction TFT and the amplification TFT share 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 light sensor is facilitated.
In summary, although the present invention has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, therefore, the scope of the present invention shall be determined by the appended claims.
Claims (10)
1. A light sensor, comprising:
an induction substrate;
the cover plate is arranged opposite to the induction substrate at intervals;
the light sensor array comprises a plurality of light sensor array units, a sensing substrate and a cover plate, wherein the light sensor array units are arranged on the sensing substrate and are positioned between the sensing substrate and the cover plate, each light sensor array unit comprises 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, and the second active layer is made of an 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 a detected optical signal into an electric signal, the storage capacitor is used for storing charges according to the electric signal in the sensing TFT, and the switching TFT controls the electric signal which is detected by the sensing TFT and amplified by the amplifying TFT to be transmitted to a signal reading circuit.
2. The light sensor of claim 1, wherein the plurality of light sensor matrix cells comprises:
the first grid, the second grid and the third grid are arranged on the induction substrate;
a gate insulating layer covering the first gate, the second gate, and the third gate;
the first active layer, the second active layer and the third active layer are arranged on the gate insulating layer, 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;
an ohmic contact layer disposed on the first active layer, the second active layer, and the third active layer;
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;
wherein the sensing TFT includes the first gate electrode, the first source electrode, and the first drain electrode, the amplifying TFT includes the second gate electrode, the second source electrode, and the second drain electrode, and the switching TFT includes the third gate electrode, the third source electrode, and the third drain electrode.
3. The light sensor of claim 2, wherein the first source is connected to the second gate and the second source is connected to the third drain.
4. The photosensor according to claim 3, further comprising a protective layer covering the sensing TFT, the amplifying TFT, and the switching TFT, wherein a first contact hole and a second contact hole are provided on the protective layer and the gate insulating layer, a conductive layer is provided in the first contact hole and the second contact hole, and the first source electrode is connected to the second gate electrode through the conductive layer in the first contact hole and the second contact hole.
5. The photosensor of claim 1, wherein the material of the second active layer is any one of IZO, In2O3, IGZO, and ZnO.
6. The optical sensor of 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 optical sensor according to claim 6, wherein the light shielding layer is made of one or more of a metal, a metal oxide, and an organic material such as a black matrix resin.
8. A method for manufacturing an optical sensor, comprising the steps of:
s10: providing an induction substrate, and forming a first grid electrode, a second grid electrode and a third grid electrode on the induction substrate through a yellow light process;
s20: forming a gate insulating layer on the sensing substrate, the gate insulating layer covering the first gate, the second gate, and the third gate;
s30: forming a first active layer, a second active layer and a third active layer on the gate insulating layer by a yellow light process, 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 by a yellow light process;
s50: forming a first source electrode and a first drain electrode, a second source electrode and a second drain electrode, and a third source electrode and a third drain electrode on the ohmic contact layer through a yellow light process, thereby forming an induction TFT, an amplification TFT and a switch TFT, wherein the induction TFT, the amplification TFT and the switch TFT form a photosensor 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 in 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 to 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 light shielding layer on one side of the cover plate close to the induction substrate, wherein the light shielding layer is arranged corresponding to the amplifying TFT and the switch TFT; and
s90: and covering the induction substrate and the cover plate mutually.
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 optical sensor according to any one of claims 1 to 7.
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