CN111933737A - Photoelectric sensor manufactured by TFT (thin film transistor) process, manufacturing method and electronic equipment - Google Patents
Photoelectric sensor manufactured by TFT (thin film transistor) process, manufacturing method and electronic equipment Download PDFInfo
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- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
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- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
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- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
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- G06V40/1318—Sensors therefor using electro-optical elements or layers, e.g. electroluminescent sensing
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Abstract
The invention aims to provide a photoelectric sensor manufactured by a TFT (thin film transistor) process, a manufacturing method and electronic equipment. In the photoelectric sensor, the photosensitive area of the photosensitive diode in each photosensitive pixel unit at least partially covers the surface of the thin film transistor, so that the photosensitive area in the photosensitive pixel unit is increased, and the photosensitive layer pixel design with higher filling ratio is realized. In addition, with the development of the manufacturing and materials of the thin film transistor, the size of the thin film transistor can be further limited on the premise of achieving the same electrical function, so that the photoelectric sensor with the structure can obtain a higher photosensitive filling proportion, and the pixel density, the resolution ratio, the signal-to-noise ratio and other performances of the photoelectric sensor can be further improved.
Description
Technical Field
The invention relates to the technical field of fingerprint identification, in particular to the field of optical fingerprint identification.
Background
Fingerprint identification is a biometric identification method, and is widely applied to the field of electronic equipment. At present, capacitance fingerprint identification and optical fingerprint identification are common in fingerprint identification. Both types of fingerprinting have a large number of products on the market today.
In the field of optical fingerprint identification, an optical fingerprint identification module, which is formed by matching a photosensitive fingerprint identification chip manufactured by a semiconductor process with an optical component, is common, and has been widely applied to many electronic devices, such as smart phones.
Currently, optical fingerprint modules are limited to a specific area for fingerprint identification in known applications. And the area of this particular area is not so large that it may only accommodate the size of one finger. For large area fingerprinting, for example, two or more fingers may be placed; or when the fingerprint identification is not limited to a specific area any more, a plurality of photosensitive fingerprint identification chips manufactured by the semiconductor process are needed to complete the fingerprint identification of a larger area. Therefore, in large-area fingerprint identification, the photosensitive fingerprint identification chip manufactured by adopting a plurality of semiconductor processes can greatly increase the cost of the optical fingerprint module, and thus the application of the photosensitive fingerprint identification chip in large-area optical fingerprint identification is hindered.
When the photosensitive identification photoelectric sensor is manufactured by using a TFT (thin film transistor) process, the manufacturing cost of the photosensitive fingerprint identification sensor is lower than that of a semiconductor photosensitive fingerprint identification chip while the photosensitive fingerprint identification sensor with a large area is easy to realize.
At present, the photoelectric sensor manufactured by the TFT technology is still in the research and development process, and large-scale mass production products are not produced in the market. The TFT process is commonly applied to the manufacture of display panels, and is also a new technical attempt in the industry for manufacturing photoelectric sensors in optical fingerprint identification modules.
Disclosure of Invention
The invention aims to provide a photoelectric sensor manufactured by a TFT (thin film transistor) process, a manufacturing method and electronic equipment.
According to one aspect of the present invention, there is provided a photosensor including a plurality of photosensitive pixel cells, each of the photosensitive pixel cells being disposed on a substrate; each of the photosensitive pixel cells includes:
a thin film transistor having a gate electrode, a gate insulating layer, an active layer, and source and drain electrodes positioned at both sides of the active layer; the photosensitive diode is provided with a first electrode layer, a photosensitive area and a second electrode layer, and the photosensitive area is arranged between the first electrode layer and the second electrode layer;
the first electrode layer of the photosensitive diode is electrically connected with the source electrode and the drain electrode of the thin film transistor; and the photosensitive area of the photosensitive diode at least partially covers the surface of the thin film transistor.
In the above-described photosensor, the thin film transistor is formed in close contact with the substrate, and the photodiode is formed above the thin film transistor and close to the photosensor surface.
Further, in the above photoelectric sensor, a medium layer between the surface of the active layer of the thin film transistor and the surface of the photosensitive pixel unit is made of a light-transmitting material.
Further, in the above photoelectric sensor, the dielectric layer includes a first electrode layer, a photosensitive region, and a second electrode layer of the photodiode.
Furthermore, in the photoelectric sensor, the active layer material of the thin film transistor is an indium gallium zinc oxide film.
Further, in the above photoelectric sensor, the thin film transistor includes: and the channel protection layer is arranged on the surface of the active layer.
Further, in the above photoelectric sensor, the gate insulating layer and the channel protection layer each include a silicon oxide layer, and the silicon oxide layers are disposed to be close to the active layer.
Further, in the above photoelectric sensor, the second electrode layer of the photodiode is electrically connected to the peripheral chip of the photoelectric sensor.
Further, in the above photoelectric sensor, a lead layer is disposed on a surface of the photodiode, and the lead layer connects the second electrode layer of the photodiode with the peripheral chip.
Further, in the above photoelectric sensor, a projection of the lead layer on the substrate at least partially covers the thin film transistor.
Further, in the above photoelectric sensor, the surface of the lead layer is covered with an insulating protection layer of the photoelectric sensor.
Further, in the photoelectric sensor, the lead layer is made of a transparent conductive ITO material.
In the photoelectric sensor, the substrate is made of glass or flexible polyimide.
The invention also provides a preparation method, wherein a thin film transistor is formed on the substrate, and the thin film transistor is provided with a grid electrode, a grid electrode insulating layer, an active layer, a source electrode and a drain electrode, wherein the source electrode and the drain electrode are positioned at two sides of the active layer;
manufacturing a photosensitive diode on the substrate on which the thin film transistor is formed, wherein the photosensitive diode is provided with a first electrode layer, a photosensitive area and a second electrode layer, and the photosensitive area is arranged between the first electrode layer and the second electrode layer;
forming a lead layer, and electrically communicating one end of the photosensitive diode with a peripheral chip of the photoelectric sensor; and
forming a protective layer on the surface of the photoelectric sensor;
wherein the projection of the formed photodiode on the substrate at least partially covers the thin film transistor.
Further, the photosensitive diode is formed after the thin film transistor is manufactured on the substrate.
Further, forming the thin film transistor on the substrate includes:
forming a grid electrode of the thin film transistor;
forming a gate insulating layer of the thin film transistor;
forming an active layer of the thin film transistor; and
and forming a source electrode and a drain electrode of the thin film transistor.
Further, forming the thin film transistor further includes forming a channel protection layer of the thin film transistor, the channel protection layer covering a source and a drain of the thin film transistor.
Furthermore, when an active layer of the thin film transistor is formed, the active layer is made of an indium gallium zinc oxide material.
Further, forming the photodiode includes: forming a first electrode layer of the photosensitive diode; forming a photosensitive area of the photosensitive diode and forming a second electrode layer of the photosensitive diode; projections of a first electrode layer, a photosensitive area and a second electrode layer of the photosensitive diode on the substrate at least partially cover the thin film transistor.
The invention also proposes a photosensor module comprising:
the above-described photoelectric sensor;
a gate driving chip;
reading out the driving chip;
the gate driving chip is electrically communicated with the grid of the thin film transistor in the photosensitive pixel unit; the reading driving chip is respectively connected with the first electrical property of the photosensitive diode and the source/drain in the thin film transistor.
The invention also provides an optical fingerprint identification module, which is provided with a fingerprint identification area, and comprises:
the photoelectric sensor module is arranged below the fingerprint identification area;
and the excitation light source is arranged below the fingerprint identification area and used for emitting detection light to a target object on the fingerprint identification area.
The present application further provides an electronic device with an optical fingerprint recognition function, including:
the display screen, the fingerprint identification area positioned in the display screen area and the photoelectric sensor module are arranged in the display screen area;
the photoelectric sensor module is arranged below the display screen.
Compared with the prior art, in the photoelectric sensor, because no light blocking layer is arranged above the surface of the thin film transistor of each photosensitive pixel unit, the photosensitive area of the photosensitive diode can at least partially cover the surface of the thin film transistor, so that the photoelectric sensor has a simple structure, the area of the photosensitive diode in each photosensitive pixel unit is enlarged, and the filling proportion of the photosensitive area in the photoelectric sensor is improved.
In the photoelectric sensor, the active layer material of the thin film transistor is the indium gallium zinc oxide film, and the thin film transistor has high on-state current, low off-state current and good visible light stability, so that the photoelectric sensor has the advantages of supporting high refresh frequency, high signal-to-noise ratio, 100% photosensitive area filling ratio pixel design, low cost and the like.
The photoelectric sensor is applied to the electronic equipment, and is beneficial to improving the photosensitive area of the electronic equipment, further improving the fingerprint detection signal quantity and improving the fingerprint identification effect.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:
FIG. 1 illustrates a cross-sectional schematic view of a light-sensing pixel cell;
FIG. 2 shows a simplified cross-sectional view of a light sensing pixel cell corresponding to FIG. 1;
FIG. 3 is a schematic cross-sectional view illustrating a design of a light sensing pixel cell in a photosensor fabricated by a TFT process according to the present application;
FIG. 4 shows a simplified cross-sectional view of a light-sensitive pixel cell corresponding to the photosensor shown in FIG. 3;
FIG. 5 shows a photosensor circuit basic architecture schematic;
FIG. 6 shows a comparison of a thin film transistor layout for an α -Si process with a thin film transistor layout for an IGZO process;
fig. 7 shows a process flow of a photosensor manufactured by a TFT process.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.
In order to make the technical solutions of the present invention better understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. "upper", "lower", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
Please refer to fig. 5, which is a schematic circuit diagram of a photosensor in the TFT optical fingerprint recognition module. As shown in fig. 5, the photosensor includes a number of light-sensitive pixel cells in an array. Each pixel cell will include a Thin Film Transistor (TFT)41 and a Photodiode (PD) 42. One end of the drain or the source of the TFT 41 is electrically connected to one end of the photodiode.
Please refer to fig. 1 and 2, which are schematic cross-sectional views of a light sensing pixel unit in a photosensor manufactured by the TFT process. In the photoelectric sensor manufactured by the TFT process shown in fig. 2, a thin film transistor 21 and a photodiode 22 are generally used as a photosensitive pixel unit to realize fingerprint identification and detection. The thin film transistor 21, which is a pixel driver of the light-sensing pixel unit, generally employs an amorphous silicon (α -Si) thin film process. Fig. 1 is a schematic diagram of a cross-sectional structure of a photosensitive pixel cell fabricated using a TFT process.
As shown in fig. 1, a single light-sensing pixel cell includes a TFT thin film transistor and a light-sensing diode. The TFT thin film transistor device layer includes: a gate electrode 2, a gate insulating layer 3, and an active layer 4, and source/drain electrodes 5 and drain/source electrodes 6. In this schematic diagram, the TFT thin film transistor surface also has a channel protection layer 7. The photodiode includes two electrode layers: a first electrode layer 8 and a second electrode layer 10 and a photosensitive layer 9 disposed between the two electrode layers. The photosensitive layer 9 may also be referred to as an intrinsic semiconductor layer. A bias conductive layer 13 and an insulating protective layer 12 are provided on the surface of the photodiode. As can be seen from fig. 1, the light blocking layer 11 is further disposed at a position right above the TFT thin film transistor, so as to prevent the TFT thin film transistor from being unstable in performance due to light sensing.
Fig. 2 is a simplified schematic diagram of the structure of a single light-sensitive pixel cell shown in fig. 1. The TFT thin film transistor 21 and the photodiode 22 are disposed substantially adjacently in one photosensitive pixel unit, and have a light blocking layer 11 above the TFT thin film transistor 21 to prevent the TFT thin film transistor 21 from being irradiated with light. Since the current TFT process usually uses an amorphous silicon (α -Si) thin film transistor, and the thin film transistor occupies a large area in the photosensitive pixel unit and has poor stability of visible light, the light blocking layer 11 needs to be added.
The photosensor manufactured by the TFT process shown above has a small photosensitive area of the photosensitive diode in the photosensor shown in fig. 1, which further results in a small photosensitive area in a single photosensitive pixel unit, and is not favorable for improving the pixel density or the photosensitive performance of the photosensor.
As shown in fig. 3 and 4, the present embodiment provides a photosensor including a plurality of photosensitive pixel cells, each of which is disposed on a substrate 31; each photosensitive pixel cell includes: a thin film transistor 41 and a photodiode 42. The first electrode of the photodiode 42 is connected to the source/drain 36 of the thin film transistor 41. The thin film transistor 41 is disposed on the substrate 31, and the light sensing region 39 of the photodiode at least partially covers the surface of the thin film transistor 41. The thin film transistor 41 serves as a pixel driver of the light-sensing pixel unit, and the light-sensing diode 42 senses and converts a light signal into an electrical signal.
The thin film transistor manufactured by the TFT process illustrated in fig. 3 includes: and a gate electrode 32 formed on the surface of the substrate 31. And a gate insulating layer 33 covering the surface of the gate electrode 32. The active layer 34 is formed on the surface of the gate insulating layer 33 and over the gate electrode 32. The source/drain 35 and the drain/source 36 are located on both sides of the active layer 34. The channel protective layer 37 covers a part of the surface of the active layer 34 and also covers a part of the source/drain electrodes 35 and the drain/source electrodes 36 above the active layer 34. The photodiode 42 includes: the first electrode layer 38, the photosensitive region 39 and the second electrode layer 310 are sequentially arranged along a direction away from the substrate 31. In the single light-sensitive pixel cell illustrated in fig. 3, the surface of the second electrode layer 310 of the light-sensitive diode is also covered with a bias voltage transfer layer 311 and a protective layer 312 that ultimately protects the light-sensitive pixel cell.
The bias conductive layer 311 is a transparent conductive ITO (Indium tin oxide) material. The dielectric layer between the surface of the active layer 37 and the surface of the photosensitive region 39 of the thin film transistor is made of a light-transmitting material. Since the bias conducting layer 311 and the second electrode layer 310 of the photodiode at least partially cover the photosensitive region 39, the bias conducting layer and the second electrode layer of the photodiode are made of transparent conductive materials. Thus, the reduction of the photosensitive area of the photosensitive region 39 can be avoided.
In view of the structure of the TFT and the photodiode in a single light-sensing pixel cell shown in fig. 3, one end of the photodiode is electrically connected to one end of the TFT.
Fig. 4 is a simplified schematic diagram of a single light-sensitive pixel cell structure shown in fig. 3. The photosensitive region 39 of the photodiode 42 is shown as fully covering the surface of the tft 41. Referring to fig. 2, which corresponds to the schematic view of a single light-sensitive pixel cell in fig. 1, the light-sensitive portion of the photodiode 42 is extended to the surface above the tft as shown in fig. 4. As can be seen by comparing the structures shown in fig. 4 and fig. 2, the photosensitive region in the photodiode shown in fig. 4 can extend above the tft, increasing the photosensitive area in a single photosensitive pixel unit. Providing more room for improving the light sensing performance of a single light-sensing pixel unit. The photosensitive pixel unit structure can realize the pixel design of a photosensitive layer with higher filling proportion and realize a photoelectric sensor with high resolution.
The transistors of the thin films shown in fig. 1 and 3 are each a bottom gate type thin film transistor. The material of the gate electrode in the thin film transistor is usually a metal, and may be a metal such as copper or molybdenum. Drain and source electrodesThe metal is also used, for example, a metal such as Mo/Cu/Mo. The material selected for the active layer in the thin film transistor shown in fig. 3 is amorphous Indium Gallium Zinc Oxide (IGZO). The gate insulating layer may adopt a double-layer SiNx/SiOxOr a single layer of SiOx. When IGZO material is selected as the active layer of the thin film transistor, SiO in the gate insulating layerxPart of the active layer needs to be arranged close to the active layer. A channel protection layer is also formed on the surface of the active layer. The channel protective layer can adopt double-layer SiNx/SiOxOr a single layer of SiOxThe structure of (1), wherein SiO is in the channel protection layerxThe material portion needs to be disposed closely to the active layer.
The foregoing is illustrative and description of a single light-sensitive pixel cell. A photosensor fabricated by TFT technology will actually include multiple light-sensitive pixel cells. The number of photosensitive pixel units included in the photosensor varies according to the area of the photosensor. A plurality of photosensitive pixel units are distributed in an array. The substrate carrying the light-sensitive pixel cells may be a glass substrate or a flexible polyimide.
The structure and materials of the thin film transistor shown in fig. 3 described above may realize the structure of the thin film transistor to realize the photosensitive region of the photodiode disposed above the thin film transistor in the single pixel unit shown in fig. 3. Based on the improvement of the manufacturing process of the thin film transistor or future materials, the area occupied by the thin film transistor in a single photosensitive pixel unit can be reduced.
As mentioned above, in the embodiments, the thin film transistor uses IGZO as the active layer material, so that the visible light stability of the thin film transistor is excellent, and thus, the barrier layer above the thin film transistor can be omitted, the photosensitive region of the photodiode in the photosensitive pixel unit can be expanded to above the thin film transistor, and the photosensitive region above the thin film transistor can be fully utilized. Meanwhile, the thin film transistor adopts IGZO as an active layer, so that the carrier mobility of the thin film transistor is high. This mobility is approximately 10 times or more the carrier of a thin film transistor using α -Si as an active layer, and thus can also help realize a photosensor of high refresh frequency. Meanwhile, the leakage current of the thin film transistor of the IGZO is low and can be as low as 1% of that of the thin film transistor of the alpha-Si, so that the signal-to-noise ratio of the photoelectric sensor is greatly improved. Due to the change of the active layer material, the size of the thin film transistor can be reduced under the same electrical parameters or the performance of the thin film transistor. Specifically, refer to the schematic comparison of the layout dimension variation of the thin film crystal of two different active layer materials shown in fig. 6(a) and fig. 6 (b). Fig. 6(a) is a schematic diagram showing the layout dimensions of a thin film transistor with an IGZO active layer; fig. 6(b) is a schematic layout size diagram of a thin film transistor whose active layer is α -Si. As illustrated in fig. 6, the thin film transistor with IGZO as the active layer can be made smaller in size than the thin film transistor with α -Si with the same electrical parameters. Therefore, the area of the whole photosensitive pixel unit can be further reduced while the area of the photosensitive pixel unit is increased, and the area of the optical sensor manufactured by the whole TFT process can be further reduced. Alternatively, the pixel density can be made higher in the optical sensor of the TFT process under the condition of the same area.
The above is merely an example of a thin film transistor employing IGZO as the active layer, and the distribution of such a structure of the light-sensitive pixel cell shown in fig. 3 can be achieved. However, as the materials and the TFT manufacturing process are improved and advanced, the structure of the claimed photosensor should not be realized by using IGZO as the active layer of the thin film transistor. Here, a thin film transistor of an active layer made of IGZO is described as an example, but not limited thereto.
In the module of the photosensor described above, only the photosensor section is fabricated by the TFT process as the light-sensing section. Please refer to fig. 5, which is a schematic diagram of a photo sensor module for optical fingerprint recognition. In order to enable the photosensor module to recognize signal light carrying fingerprint information, the photosensor module usually includes a gate driving chip 52 of a thin film crystal in a photosensor fabricated by TFT operation, and a readout driving chip 51 for processing an electrical signal output from the photosensor. The gate driving chip 52 is electrically connected to the gate of the thin film transistor 41 in the photosensitive pixel unit; the readout driving chip 51 is connected to the second electrode of the photodiode 42 and the drain/source of the thin film transistor 41, respectively.
Of course, in some photosensor modules, the circuit of the gate driving chip can also be directly integrated with the photosensor by using the TFT process, or the gate driving circuit can be formed around the photosensor. This helps to save the manufacturing cost of the optical fingerprint identification module.
When the above-described photosensor module is applied to an optical fingerprint identification module, the optical fingerprint identification module needs to determine an excitation light source for irradiating a target object. In a relatively common example of an application of a smart device, for a display screen with self-luminescence, the excitation light source usually directly uses the light signal generated by the display screen as the excitation light source. Aiming at the display screen of the backlight mode and aiming at the optical fingerprint identification module, the common excitation light source is an infrared or near-infrared excitation light source. Of course, it is not excluded that other wavelength bands of light source signals may be used in the backlight module, and the excitation light sources are not limited to those illustrated herein. In a smart device to which the photoelectric sensor is applied, if there is no display screen or there is a display screen and the fingerprint identification area is not on the display screen, an excitation light source needs to be separately provided for illuminating a target object. The excitation light source is generally disposed below the fingerprint identification area to emit an excitation light signal to a target object within the fingerprint identification area.
Above the photoelectric sensor, an optical processor for processing the signal light reflected by the target object is also required. An optical processor for receiving the signal light prior to the photoelectric sensor; the signal light processed by the optical processor reaches the photosensor. The optical processor disposed above the optical path of the photo-sensor manufactured by TFT process generally includes an optical collimating panel, a micro-lens collimator, and the like.
The second aspect of the present application describes one embodiment of a method for fabricating a photosensor corresponding to the TFT process shown in fig. 3.
Due to the structure of the photo-sensor manufactured by the TFT process shown in fig. 3, it can be roughly seen that the structure of the photodiode in the photo-sensor is located on the surface of the thin film transistor. Therefore, the general TFT process flow of the photosensor manufactured by the TFT process is illustrated with reference to fig. 7. Firstly, manufacturing a thin film transistor on a substrate; manufacturing a photosensitive diode on the substrate on which the thin film crystal light is formed; after the device is manufactured, a lead layer is manufactured for leading out pins which are electrically connected with the device layer to the outside.
In general, the TFT process flow of the method for fabricating the photo sensor shown in fig. 7 is simplified compared to the method for fabricating the photo sensor shown in fig. 1. Because the light blocking layer above the thin film transistor is omitted, the number of light shades used in the TFT process can be reduced relatively, and the manufacturing flow of the whole photoelectric sensor is shortened. Therefore, the manufacturing cost of the whole photoelectric sensor is favorably reduced.
The following will describe a method of manufacturing the photosensor shown in fig. 7 in more detail.
The thin film transistor is firstly manufactured on the substrate, and the grid electrode, the drain electrode and the source electrode of the thin film transistor are formed. Taking the thin film transistor shown in fig. 3 as a bottom gate thin film transistor as an example, a metal layer for forming a gate electrode of the thin film transistor is formed on a substrate and patterned. And forming a gate insulating layer on the surface of the gate. And forming an active layer on the surface of the gate insulating layer, and then forming a source electrode and a drain electrode of the thin film transistor. And finally, forming a channel protection layer on the surface of the thin film transistor. Only the fabrication of the bottom gate type thin film transistor will be described and illustrated herein. The order of fabricating the layers of the tft may be adjusted accordingly according to the type of the tft.
As described in the above structural embodiments, to avoid forming the light blocking layer above the thin film transistor, the active layer of the thin film transistor may be made of IGZO material. Since the active layer is made of IGZO material, the gate insulating layer and the silicon oxide SiO in the channel protection layer are as described in the above structural embodimentsxNeed to be tightly attached to the active layer for manufacturing, and prevent the IGZO material from deoxidizingAnd (6) originally.
After the thin film transistor is substantially completed, a photodiode is formed on the substrate on which the thin film transistor is formed. The thin film transistor and the photodiode are electrically connected, so that a channel protection layer on the surface of the thin film transistor needs to be patterned, and an electrical connection end, such as a source electrode or a drain electrode, of the thin film transistor needs to be exposed and electrically connected with the photodiode. One of the two electrodes of the photodiode, such as the first electrode layer, that needs to be electrically connected to the thin film transistor can then be formed. The first electrode layer of the photodiode can extend to a position which needs to be covered by a photosensitive region of a subsequent photodiode, and then a photosensitive region layer of the photodiode is formed, wherein the area of the first electrode layer can be approximately the same as that of the photosensitive region layer, so that an electric signal after photoelectric conversion can be received better. And then, manufacturing a second electrode layer of the photodiode, wherein the area of the second electrode layer can be approximately the same as that of the photosensitive region layer, so as to better receive the electric signal after photoelectric conversion. And after the photosensitive diode is manufactured, covering an insulating medium layer on the surface of the photosensitive diode. The insulating medium layer can be used as a protective layer of the photosensitive diode.
As shown in fig. 5, the connection relationship between each photosensitive pixel unit and the readout chip in the photosensor module indicates that the second electrode layer of the photodiode needs to be electrically led out, and therefore, a lead layer needs to be formed. The fabrication of the lead layer includes forming a bias conducting layer as shown in fig. 3 to enable electrical lead-out of the second electrode of the photodiode. Before the bias conducting layer is manufactured, the insulating medium layer on the surface of the photosensitive diode needs to be patterned, and the insulating medium on the corresponding position is removed at the position where electrical leading-out is needed.
It should be understood that the above embodiments are only exemplary embodiments adopted for illustrating the principle of the present invention, and the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.
Claims (22)
1. A photoelectric sensor manufactured by a TFT (thin film transistor) process is characterized by comprising a plurality of photosensitive pixel units, wherein each photosensitive pixel unit is arranged on a substrate; each of the photosensitive pixel cells includes:
a thin film transistor having a gate electrode, a gate insulating layer, an active layer, and source and drain electrodes positioned at both sides of the active layer; the photosensitive diode is provided with a first electrode layer, a photosensitive area and a second electrode layer, and the photosensitive area is arranged between the first electrode layer and the second electrode layer;
the first electrode layer of the photosensitive diode is electrically connected with the source/drain of the thin film transistor; and the photosensitive area of the photosensitive diode at least partially covers the surface of the thin film transistor.
2. The photosensor of claim 1 wherein the thin film transistor is formed proximate the substrate and the photodiode is formed above the thin film transistor and proximate the photosensor surface.
3. The photosensor manufactured by the TFT process of claim 1 wherein a dielectric layer between the surface of the active layer of the thin film transistor and the surface of the photosensor is a light transmissive material.
4. The photosensor produced by the TFT process of claim 3 wherein the dielectric layer comprises a first electrode layer, a photosensitive region and a second electrode layer of the photodiode.
5. The photosensor manufactured by the TFT process of claim 1 wherein an active layer material of the thin film transistor is an indium gallium zinc oxide film.
6. The photosensor produced by the TFT process of claim 5 wherein the thin film transistor further comprises: and the channel protection layer is arranged on the surface of the active layer.
7. The photosensor produced by the TFT process of claim 6 wherein the gate insulating layer and the channel protective layer each comprise a silicon oxide layer, and the silicon oxide layers are disposed adjacent to the active layer.
8. The photosensor manufactured by the TFT process of claim 1, wherein the second electrode layer of the photodiode is electrically connected to a peripheral chip of the photosensor.
9. The photosensor manufactured by the TFT process of claim 8, wherein a surface of the photodiode is provided with a wiring layer that connects the second electrode layer of the photodiode with the peripheral chip.
10. The photosensor produced by the TFT process of claim 9 wherein a projection of the wiring layer onto the substrate at least partially covers the thin film transistor.
11. The photosensor manufactured by the TFT process of claim 10 wherein the surface of the lead layer is covered with an insulating protective layer of the photosensor.
12. The photosensor made by TFT processing of claim 10 wherein the lead layer is a transparent conductive ITO material.
13. The photosensor manufactured by the TFT process of any of claims 1-12 wherein the substrate is made of glass or flexible polyimide.
14. A method for manufacturing a photosensor by TFT technology, the photosensor being the photosensor according to any one of claims 1 to 13, the method comprising:
forming a thin film transistor on the substrate, the thin film transistor having a gate electrode, a gate insulating layer, an active layer, and source and drain electrodes positioned at both sides of the active layer;
manufacturing a photosensitive diode on the substrate on which the thin film transistor is formed, wherein the photosensitive diode is provided with a first electrode layer, a photosensitive area and a second electrode layer, and the photosensitive area is arranged between the first electrode layer and the second electrode layer;
forming a lead layer, and electrically communicating one end of the photosensitive diode with a peripheral chip of the photoelectric sensor; and
forming a protective layer on the surface of the photoelectric sensor;
wherein the projection of the formed photodiode on the substrate at least partially covers the thin film transistor.
15. The method of claim 14, wherein forming the photodiode is performed on the substrate after the thin film transistor is completed.
16. The method of claim 14, wherein forming the thin film transistor on the substrate comprises:
forming a grid electrode of the thin film transistor;
forming a gate insulating layer of the thin film transistor;
forming an active layer of the thin film transistor; and
and forming a source electrode and a drain electrode of the thin film transistor.
17. The method of claim 16, wherein forming the thin film transistor further comprises forming a channel protection layer of the thin film transistor, the channel protection layer covering a source and a drain of the thin film transistor.
18. The method of claim 16, wherein an active layer of the thin film transistor is formed by using an indium gallium zinc oxide material.
19. The method of claim 14, wherein forming the photodiode comprises: forming a first electrode layer of the photosensitive diode; forming a photosensitive area of the photosensitive diode and forming a second electrode layer of the photosensitive diode; projections of a first electrode layer, a photosensitive area and a second electrode layer of the photosensitive diode on the substrate at least partially cover the thin film transistor.
20. A photosensor module, comprising:
the photosensor of any one of claims 1-13;
a gate driving chip;
reading out the driving chip;
the gate driving chip is electrically communicated with the grid of the thin film transistor in the photosensitive pixel unit; the reading driving chip is respectively connected with the first electrical property of the photosensitive diode and the drain electrode in the thin film transistor.
21. The utility model provides an optics fingerprint identification module is equipped with the fingerprint identification district, includes:
the photosensor module of claim 20 disposed below the fingerprint identification region;
an optical processor disposed above the photosensor;
and the excitation light source is arranged below the fingerprint identification area and used for emitting detection light to a target object on the fingerprint identification area, and the detection light reflected by the target object reaches the photoelectric sensor after being processed by the optical processor.
22. An electronic device with optical fingerprint recognition functionality, comprising:
a display screen, a fingerprint identification area located within an area of the display screen, and the optical fingerprint identification module of claim 21;
the photoelectric sensor module is arranged below the display screen.
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| CN108269817A (en) * | 2018-01-19 | 2018-07-10 | 京东方科技集团股份有限公司 | Array substrate, manufacturing method and the X ray sensor of X ray sensor |
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| CN1751393A (en) * | 2003-02-14 | 2006-03-22 | 佳能株式会社 | Solid state image pickup apparatus and radiation image pickup apparatus |
| CN102768989A (en) * | 2011-05-06 | 2012-11-07 | 京东方科技集团股份有限公司 | Thin film transistor array substrate structure and manufacturing method |
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