CN112420791B

CN112420791B - Fingerprint identification substrate, preparation method thereof and display device

Info

Publication number: CN112420791B
Application number: CN202011281186.4A
Authority: CN
Inventors: 耿越; 李成; 王奎元; 祁朝阳; 丰亚洁; 代翼; 李泽飞; 李想
Original assignee: BOE Technology Group Co Ltd; Beijing BOE Sensor Technology Co Ltd
Current assignee: BOE Technology Group Co Ltd; Beijing BOE Sensor Technology Co Ltd
Priority date: 2020-11-16
Filing date: 2020-11-16
Publication date: 2024-02-27
Anticipated expiration: 2040-11-16
Also published as: CN112420791A

Abstract

The disclosure provides a fingerprint identification substrate, a manufacturing method thereof and a display device. The fingerprint identification substrate comprises a substrate, a fingerprint sensing layer arranged on the substrate and a collimation and light filtering structure layer arranged on one side of the fingerprint sensing layer away from the substrate, wherein the collimation and light filtering structure layer comprises a unthreaded hole layer, a light modulation layer and a lens layer which are sequentially arranged along the direction away from the substrate, and the light modulation layer is used for adjusting the focal length of the lens layer and cutting off infrared light. According to the fingerprint identification module, the unthreaded hole layer, the optical modulation layer and the lens layer are integrated into the collimation filter structure layer, the optical modulation layer arranged between the unthreaded hole layer and the lens layer is used for cutting off external infrared light rays and adjusting the focal length of the lens in the lens layer, the thickness of the fingerprint identification substrate is effectively reduced, and the problem that the thickness of an existing fingerprint identification module is large is effectively solved.

Description

Fingerprint identification substrate, preparation method thereof and display device

Technical Field

The invention relates to the technical field of display, in particular to a fingerprint identification substrate, a preparation method thereof and a display device.

Background

Fingerprint recognition of display devices (such as notebook computers, tablet computers, mobile phones, etc.) is gradually changing from capacitive fingerprint recognition to optical fingerprint recognition. The optical fingerprint identification uses refraction and reflection of light to image the fingerprint of the user, then identifies fingerprint characteristics by an image identification method, has the characteristics of high imaging resolution, easier image identification and the like, and can be arranged below a display screen to form the fingerprint identification under the screen.

The current mass-produced optical fingerprint module is a single-finger silicon-based CMOS detector, and is limited by the manufacturing cost and the process difficulty of a semiconductor device, and the silicon-based CMOS fingerprint module is difficult to develop towards the direction under a large-area screen. At present, in the fingerprint technology under the glass base screen, the fingerprint identification module with the optical collimating device has better performance, and is favorable for developing to the direction under the large-area screen. However, due to the addition of the optical collimating device, the fingerprint identification module of the product has larger universal thickness and does not accord with the development trend of light and thin display devices.

Disclosure of Invention

The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

The technical problem to be solved by the present disclosure is to provide a fingerprint identification substrate, a preparation method thereof, and a display device, so as to overcome the defect of the existing structure that the thickness is larger.

In order to solve the technical problem, the present disclosure provides a fingerprint identification substrate, including the base, set up fingerprint sensing layer on the base and set up in fingerprint sensing layer keep away from the collimation filter structure layer of base one side, collimation filter structure layer includes along keeping away from unthreaded hole layer, light modulation layer and the lens layer that the base direction set gradually, the light modulation layer is used for the adjustment the focus on lens layer and cut off infrared light.

In an exemplary embodiment, the fingerprint sensing layer includes a thin film transistor and a photodiode disposed on the substrate; the thin film transistor includes a gate electrode, an active layer, a source electrode, and a drain electrode, and the photodiode includes a first electrode, a photoelectric conversion layer, and a second electrode; the drain electrode of the thin film transistor is arranged on the same layer as the first electrode of the photodiode.

In an exemplary embodiment, the fingerprint sensing layer further includes a second insulating layer disposed on a side of the thin film transistor away from the substrate, a first via hole exposing the first electrode is disposed on the second insulating layer, and the photoelectric conversion layer is connected to the first electrode through the first via hole.

In an exemplary embodiment, the fingerprint sensing layer further includes a planarization layer and a third insulation layer disposed on a side of the second insulation layer away from the substrate, the planarization layer and the third insulation layer being provided with a second via hole exposing the photoelectric conversion layer, the second electrode being disposed on the third insulation layer and connected with the photoelectric conversion layer through the second via hole.

In an exemplary embodiment, the fingerprint sensing layer further comprises a power line disposed on a side of the second electrode remote from the substrate, and an orthographic projection of the power line on the substrate comprises an orthographic projection of a channel region of the thin film transistor on the substrate.

In an exemplary embodiment, the light hole layer is disposed at a side of the second electrode remote from the substrate, and the light hole layer includes at least one light hole forming a light transmission channel.

In an exemplary embodiment, the photo hole layer has a thickness of 5 μm to 10 μm and the photo hole has a hole diameter of 3 μm to 8 μm.

In an exemplary embodiment, the lens layer is disposed on a side of the light modulation layer remote from the substrate, the lens layer including at least one lens having a focal point located on an axis of the at least one light aperture.

In an exemplary embodiment, the thickness of the lens layer is 5 μm to 10 μm.

In an exemplary embodiment, the light modulation layer includes a reflective light modulation layer including at least one first sub-layer and a second sub-layer alternately disposed, the first sub-layer having a refractive index different from that of the second sub-layer, and the reflective light modulation layer has a thickness of 30 μm to 50 μm.

In an exemplary embodiment, the light modulation layer includes an absorption type light modulation layer including a blue-green photosensitive acrylic resin, and the absorption type light modulation layer has a thickness of 30 μm to 50 μm.

The disclosure also provides a display device, which comprises the fingerprint identification substrate.

The disclosure also provides a method for preparing the fingerprint identification substrate, comprising:

forming a fingerprint sensing layer on a substrate;

forming a collimation filter structure layer on one side of the fingerprint sensing layer far away from the substrate; the collimation filter structure layer comprises a unthreaded hole layer, a light modulation layer and a lens layer which are sequentially arranged along the direction far away from the substrate, and the light modulation layer is used for adjusting the focal length of the lens layer and cutting off infrared light.

In an exemplary embodiment, forming a collimation filter structure layer on the fingerprint sensing layer includes:

forming the light hole layer on the fingerprint sensing layer, wherein the light hole layer comprises at least one light hole;

forming a light modulation layer on the light hole layer;

a lens layer is formed over the light modulation layer, the lens layer comprising at least one lens having a focal point located on an axis of the at least one light aperture.

In an exemplary embodiment, the light modulation layer includes a reflective light modulation layer including at least one first sub-layer and a second sub-layer alternately disposed, the first sub-layer having a refractive index different from a refractive index of the second sub-layer; or,

The light modulation layer includes an absorption type light modulation layer including a blue-green photosensitive acrylic resin.

According to the fingerprint identification substrate provided by the exemplary embodiment of the disclosure, the unthreaded hole layer, the optical modulation layer and the lens layer are integrated into the collimation filter structure layer, the optical modulation layer arranged between the unthreaded hole layer and the lens layer is used for cutting off external infrared light rays and adjusting the focal length of the lens in the lens layer, so that the thickness of the fingerprint identification substrate is effectively reduced, and the problem that the thickness of the existing fingerprint identification module is large is effectively solved.

Of course, not all of the above-described advantages need be achieved simultaneously in practicing any one of the products or methods of the present disclosure. Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the disclosure. The objectives and other advantages of the disclosure will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description.

Drawings

The accompanying drawings are included to provide an understanding of the technical aspects of the present application, and are incorporated in and constitute a part of this specification, illustrate the technical aspects of the present application and together with the examples of the present application, and not constitute a limitation of the technical aspects of the present application.

Fig. 1 is a schematic structural diagram of a fingerprint recognition substrate according to an exemplary embodiment of the present disclosure;

FIG. 2 is a cross-sectional view taken along the direction A-A in FIG. 1;

FIG. 3 is a schematic illustration of an exemplary embodiment of the present disclosure after forming a first conductive layer pattern;

FIG. 4 is a cross-sectional view taken along the direction A-A in FIG. 3;

fig. 5 is a schematic diagram of a semiconductor layer after patterning according to an exemplary embodiment of the present disclosure;

FIG. 6 is a cross-sectional view taken along the direction A-A in FIG. 5;

fig. 7 is a schematic diagram of a semiconductor layer after patterning according to an exemplary embodiment of the present disclosure;

FIG. 8 is a cross-sectional view taken along the direction A-A in FIG. 7;

fig. 9 is a schematic view of a second insulating layer pattern formed according to an exemplary embodiment of the present disclosure;

FIG. 10 is a cross-sectional view taken along the direction A-A in FIG. 9;

fig. 11 is a schematic view after forming a pattern of a photoelectric conversion layer according to an exemplary embodiment of the present disclosure;

FIG. 12 is a cross-sectional view taken along the direction A-A in FIG. 11;

fig. 13 is a schematic view of an exemplary embodiment of the present disclosure after forming a planarization layer and a third insulating layer pattern;

FIG. 14 is a cross-sectional view taken along the direction A-A in FIG. 13;

fig. 15 is a schematic view of an exemplary embodiment of the present disclosure after forming a second electrode pattern;

FIG. 16 is a cross-sectional view taken along the direction A-A in FIG. 15;

FIG. 17 is a schematic diagram of an exemplary embodiment of the present disclosure after forming a power line pattern;

FIG. 18 is a cross-sectional view taken along the direction A-A in FIG. 17;

FIG. 19 is a schematic diagram of an exemplary embodiment of the present disclosure after forming a light aperture layer pattern;

FIG. 20 is a cross-sectional view taken along the direction A-A in FIG. 19;

FIG. 21 is a schematic diagram of an exemplary embodiment of the present disclosure after patterning a light modulation layer;

FIG. 22 is a cross-sectional view taken along the direction A-A in FIG. 21;

FIG. 23 is a graph of transmittance of a reflective optical modulation layer according to an exemplary embodiment of the present disclosure;

fig. 24 is a transmittance curve of an absorption-type light modulation layer according to an exemplary embodiment of the present disclosure.

Reference numerals illustrate:

10-a substrate; 11-a first insulating layer; 12-a second insulating layer;

13-a planar layer; 14—a third insulating layer; 20-scanning signal lines;

21-a gate electrode; 22-an active layer; 23-a source electrode;

24-drain electrode; 30—a data signal line; 31-a first electrode;

32-a photoelectric conversion layer; 33-a second electrode; 34-a power line;

41-a light hole layer; 42—a light modulating layer; 43-lens layer.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail hereinafter with reference to the accompanying drawings. Note that embodiments may be implemented in a number of different forms. One of ordinary skill in the art can readily appreciate the fact that the manner and content may be varied into a wide variety of forms without departing from the spirit and scope of the present disclosure. Accordingly, the present disclosure should not be construed as being limited to the following description of the embodiments. Embodiments of the present disclosure and features of embodiments may be combined with each other arbitrarily without conflict.

In the drawings, the size of each constituent element, the thickness of a layer, or a region may be exaggerated for clarity. Accordingly, one aspect of the present disclosure is not necessarily limited to this dimension, and the shapes and sizes of the various components in the drawings do not reflect actual proportions. Further, the drawings schematically show ideal examples, and one mode of the present disclosure is not limited to the shapes or numerical values shown in the drawings, and the like.

The ordinal numbers of "first", "second", "third", etc. in the present specification are provided to avoid mixing of constituent elements, and are not intended to be limited in number.

In the present specification, for convenience, words such as "middle", "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, which indicate an azimuth or a positional relationship, are used to describe positional relationships of constituent elements with reference to the drawings, only for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or elements referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus are not to be construed as limiting the present disclosure. The positional relationship of the constituent elements is appropriately changed according to the direction in which the respective constituent elements are described. Therefore, the present invention is not limited to the words described in the specification, and may be appropriately replaced according to circumstances.

In this specification, the terms "mounted," "connected," and "connected" are to be construed broadly, unless explicitly stated or limited otherwise. For example, it may be a fixed connection, a removable connection, or an integral connection; may be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intermediate members, or may be in communication with the interior of two elements. The specific meaning of the terms in this disclosure will be understood by those of ordinary skill in the art in the specific context.

In this specification, a transistor means an element including at least three terminals of a gate electrode, a drain electrode, and a source electrode. The transistor has a channel region between a drain electrode (a drain electrode terminal, a drain region, or a drain electrode) and a source electrode (a source electrode terminal, a source region, or a source electrode), and a current can flow through the drain electrode, the channel region, and the source electrode. Note that in this specification, a channel region refers to a region through which current mainly flows.

In this specification, the first electrode may be a drain electrode, the second electrode may be a source electrode, or the first electrode may be a source electrode and the second electrode may be a drain electrode. In the case of using a transistor having opposite polarity, or in the case of a change in the direction of current during circuit operation, the functions of the "source electrode" and the "drain electrode" may be interchanged. Therefore, in this specification, "source electrode" and "drain electrode" may be exchanged with each other.

In this specification, "electrically connected" includes a case where constituent elements are connected together by an element having some electric action. The "element having a certain electric action" is not particularly limited as long as it can transmit and receive an electric signal between the constituent elements connected. Examples of the "element having some electric action" include not only an electrode and a wiring but also a switching element such as a transistor, a resistor, an inductor, a capacitor, other elements having various functions, and the like.

In the present specification, "parallel" means a state in which two straight lines form an angle of-10 ° or more and 10 ° or less, and therefore, a state in which the angle is-5 ° or more and 5 ° or less is also included. The term "perpendicular" refers to a state in which the angle formed by two straight lines is 80 ° or more and 100 ° or less, and thus includes a state in which the angle is 85 ° or more and 95 ° or less.

In this specification, "film" and "layer" may be exchanged with each other. For example, the "conductive layer" may be sometimes replaced with a "conductive film". In the same manner, the "insulating film" may be replaced with the "insulating layer" in some cases.

The term "about" in this disclosure refers to values that are not strictly limited to the limits, but are allowed to fall within the limits of the process and measurement errors.

The related art proposes an optical fingerprint identification module, adopts the lamination package assembly of fingerprint sensing layer, collimation light path membrane and filter membrane, and collimation light path membrane and filter membrane are all separately prepared. Wherein, the filter film is attached and connected on the fingerprint sensing substrate through first optical cement (Optically Clear Adhesive, abbreviated as OCA), the collimation light path film is attached and connected on the filter film through second optical cement, the thickness of the first optical cement and the second optical cement is about 25 μm, and the thickness of the filter film is about 30 μm to 50 μm. The collimating light path film of the related art mainly comprises a stacked unthreaded hole layer, a spacer layer and a lens layer, wherein the lens layer is used for converging fingerprint reflected light, the spacer layer is used for providing a proper focal length for the lens layer, and the unthreaded hole layer is used for limiting large-angle incident light converged by the lens layer. Since the thicknesses of the light aperture layer, the spacer layer, and the lens layer are in the range of about 5 μm to 10 μm, 30 μm to 50 μm, and 5 μm to 10 μm, respectively, the total thickness of the collimated light path film is about 40 μm to 70 μm. Thus, the total thickness of the collimating light path film and the light filtering film in the fingerprint identification module is about 120-170 μm, and the total thickness of the fingerprint identification module is about 240-320 μm.

With the development of mobile terminals (such as mobile phones), the internal structure of the mobile terminal has been increasingly required to be compact. In a mobile terminal product, the height between a display screen and a middle frame for placing a fingerprint identification module is required to be not more than 200 mu m. Because the transformation degree of the middle frame is lower, the structure of the fingerprint identification module cannot meet the design requirement, and the too thick fingerprint identification module can seriously interfere with the internal structure of the mobile terminal.

In order to overcome the problem that current fingerprint identification module thickness is great, this disclosure provides a fingerprint identification base plate. In an exemplary embodiment, the fingerprint identification substrate may include a substrate, a fingerprint sensing layer disposed on the substrate, and a collimation filter structure layer disposed on a side of the fingerprint sensing layer away from the substrate, where the collimation filter structure layer includes an optical aperture layer, an optical modulation layer, and a lens layer sequentially disposed along a direction away from the substrate, and the optical modulation layer is used for adjusting a focal length of the lens layer and cutting off infrared light.

Fig. 1 is a schematic structural view of a fingerprint recognition substrate according to an exemplary embodiment of the present disclosure, and fig. 2 is a cross-sectional view taken along A-A in fig. 1. As shown in fig. 1 and 2, the fingerprint recognition substrate includes a base 10, a plurality of scanning signal lines 20 and a plurality of data signal lines 30 disposed on the base 10, and the plurality of scanning signal lines 20 and the plurality of data signal lines 30 cross each other to form a plurality of recognition pixels arranged in a matrix. It is to be understood that the crossing of the scanning signal line and the data signal line in the present disclosure means that the projections of the scanning signal line and the data signal line on the substrate perpendicularly cross, and that the scanning signal line and the data signal line are not in direct contact with each other due to the presence of the insulating layer. At least one identification pixel comprises a fingerprint sensing layer and a collimation filter structure layer which are overlapped on a substrate 10, wherein the fingerprint sensing layer comprises a thin film transistor and a photodiode, the collimation filter structure layer comprises an overlapped unthreaded hole layer 41, a light modulation layer 42 and a lens layer 43, the lens layer 43 is used for converging reflection light of fingerprints and playing a role of collecting light, the light modulation layer 42 is used for cutting off infrared light rays so as to prevent external light rays from interfering normal fingerprint imaging, the focal length of the lens layer 43 is adjusted, and the unthreaded hole layer 41 is used for limiting large-angle incident light converged by the lens layer 43 so as to reduce crosstalk.

In an exemplary embodiment, the scan signal line 20 is connected to a Gate integrated circuit (Gate IC) of an external circuit, the data signal line 30 is connected to a read integrated circuit (ROIC) of the external circuit, the Gate integrated circuit transmits a fingerprint recognition scan signal to the scan signal line 20, and the read integrated circuit reads an electrical signal from the data signal line 30.

It should be noted that, the structures shown in fig. 1 and 2 only illustrate 3 rows and 3 columns of identification pixels, but in practice, the fingerprint identification substrate may include an array of several hundred rows and several hundred columns of identification pixels, where the array of identification pixels forms the photosensitive area of the fingerprint identification substrate.

In an exemplary embodiment, the thin film transistor and the photodiode in the fingerprint sensing layer are fabricated simultaneously on the substrate 10. The thin film transistor may include a gate electrode 21, an active layer 22, a source electrode 23, and a drain electrode 24, and the photodiode includes a first electrode 31, a photoelectric conversion layer 32, and a second electrode 33. In the thin film transistor and the photodiode which are manufactured simultaneously, the drain electrode 24 of the thin film transistor and the first electrode 31 of the photodiode may be provided in the same layer and formed by the same patterning process. In an exemplary embodiment, the drain electrode 24 and the first electrode 31 may be a unitary structure connected to each other.

In an exemplary embodiment, the fingerprint sensing layer further includes a second insulating layer 12 covering the thin film transistor, and a first via hole exposing the first electrode 31 of the photodiode is disposed on the second insulating layer 12, and the photoelectric conversion layer 32 of the photodiode is connected to the first electrode 31 of the photodiode through the first via hole.

In the exemplary embodiment, the fingerprint sensing layer further includes a planarization layer 13 and a third insulation layer 14 covering the second insulation layer 12 and the photoelectric conversion layer 32, the planarization layer 13 and the third insulation layer 14 are provided with a second via hole exposing the photoelectric conversion layer 32 of the photodiode, and a second electrode 33 of the photodiode is provided on the third insulation layer 14 and is connected to the photoelectric conversion layer 32 of the photodiode through the second via hole.

In an exemplary embodiment, a power line 34 is disposed on the second electrode 33 of the photodiode, and the orthographic projection of the power line 34 on the substrate includes the orthographic projection of the channel region of the thin film transistor on the substrate.

In an exemplary embodiment, the light hole layer 41 is disposed on the second electrode 33 of the second via hole, and the light hole layer 41 includes at least one light hole forming a light transmission channel.

In an exemplary embodiment, the light modulation layer 42 is disposed on the pupil layer 41 for cutting off external infrared light on the one hand and for adjusting focal lengths of a plurality of lenses in the lens layer 43 on the other hand such that a focal point of each lens is located on an axis of each pupil and a focal point of the lens is located at a midpoint in a depth direction of the pupil. The depth of the light hole may be a dimension of the light hole in a direction perpendicular to the plane of the substrate, and the depth direction of the light hole may be a direction perpendicular to the plane of the substrate.

In an exemplary embodiment, the lens layer 43 is disposed on the light modulation layer 42, and the lens layer 43 includes at least one lens, where the at least one lens corresponds to the at least one light hole one by one, and is used for converging the fingerprint reflected light, and playing a role of light collection.

In an exemplary embodiment, the stacked pupil layer 41, light modulation layer 42, and lens layer 43 may limit large-angle incident light rays, and may limit external infrared light rays, thereby reducing crosstalk.

In an exemplary embodiment, the light modulation layer 42 may be a reflective light modulation layer including at least one first sub-layer and a second sub-layer alternately disposed, the first sub-layer having a refractive index different from that of the second sub-layer, and the reflective light modulation layer may have a thickness of about 30 μm to 50 μm.

In an exemplary embodiment, the light modulation layer 42 may be an absorption type light modulation layer including a blue-green photosensitive acrylic resin, and the thickness of the absorption type light modulation layer may be about 30 μm to 50 μm.

An exemplary description will be made below of a manufacturing process of the fingerprint recognition substrate. The "patterning process" referred to in this disclosure includes, for metallic materials, inorganic materials, or transparent conductive materials, processes such as photoresist coating, mask exposure, development, etching, photoresist stripping, and the like, and for organic materials, processes such as organic material coating, mask exposure, and development, and the like. The deposition may be any one or more of sputtering, evaporation, chemical vapor deposition, coating may be any one or more of spraying, spin coating, and ink jet printing, and etching may be any one or more of dry etching and wet etching, without limitation of the disclosure. "film" refers to a layer of film formed by depositing, coating, or other process a material on a substrate. The "film" may also be referred to as a "layer" if the "film" does not require a patterning process throughout the fabrication process. If the "thin film" requires a patterning process throughout the fabrication process, it is referred to as a "thin film" prior to the patterning process, and as a "layer" after the patterning process. The "layer" after the patterning process includes at least one "pattern". The term "a and B are arranged in the same layer" in the present disclosure means that a and B are formed simultaneously by the same patterning process, and the "thickness" of the film layer is the dimension of the film layer in the direction perpendicular to the display substrate. In the exemplary embodiments of the present disclosure, "the orthographic projection of a includes the orthographic projection of B" means that the boundary of the orthographic projection of B falls within the boundary range of the orthographic projection of a or the boundary of the orthographic projection of a overlaps with the boundary of the orthographic projection of B.

In one exemplary embodiment, the preparation process of the fingerprint recognition substrate may include the following operations.

(1) A first conductive layer pattern is formed. In an exemplary embodiment, forming the first conductive layer pattern may include: a first metal thin film is deposited on the substrate, and patterned by a patterning process to form a first conductive layer pattern, wherein the first conductive layer includes at least a scan signal line 20 and a gate electrode 21, as shown in fig. 3 and 4, and fig. 4 is a cross-sectional view in A-A direction of fig. 3.

In an exemplary embodiment, the scan signal line 20 may extend in a horizontal direction, and the plurality of scan signal lines 20 may be parallel to one another. The gate electrode 21 is disposed in at least one of the identification pixels, and the gate electrode 21 may be of an integral structure connected to the scan signal line 20.

In an exemplary embodiment, the substrate may be a hard substrate or a flexible substrate, such as glass or Polyimide (PI). The first metal thin film may be a metal material such as any one or more of silver (Ag), copper (Cu), aluminum (Al), titanium (Ti), and molybdenum (Mo), or an alloy material of the above metals such as aluminum neodymium alloy (AlNd) or molybdenum niobium alloy (MoNb), and may be a single-layer structure or a multi-layer composite structure such as Ti/Al/Ti, or the like.

(2) A semiconductor layer pattern is formed. In an exemplary embodiment, forming the semiconductor layer pattern may include: on the substrate on which the foregoing patterns are formed, a first insulating film and a semiconductor film are sequentially deposited, the semiconductor film is patterned by a patterning process, a first insulating layer 11 is formed to cover the first conductive layer pattern, and a semiconductor layer pattern is provided on the first insulating layer 11, the semiconductor layer pattern including at least an active layer 22, as shown in fig. 5 and 6, and fig. 6 is a cross-sectional view in A-A direction of fig. 5.

In an exemplary embodiment, the active layer 22 is disposed within at least one identification pixel, and there is an overlapping area of the front projection of the active layer 22 on the substrate and the front projection of the gate electrode 21 on the substrate.

In an exemplary embodiment, the semiconductor thin film may employ an amorphous indium gallium zinc Oxide material (a-IGZO), zinc oxynitride (ZnON), indium Zinc Tin Oxide (IZTO), amorphous silicon (a-Si), polycrystalline silicon (p-Si), hexathiophene, or polythiophene, etc., i.e., the present disclosure is applicable to transistors manufactured based on Oxide (Oxide) technology, silicon technology, or organic technology. The first insulating layer may be any one or more of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON), and may be a single layer, a multi-layer, or a composite layer, and is referred to as a Gate Insulating (GI) layer.

(3) And forming a second conductive layer pattern. In an exemplary embodiment, forming the second conductive layer pattern may include: on the substrate on which the foregoing patterns are formed, a second metal thin film is deposited, and the second metal thin film is patterned by a patterning process to form a second conductive layer pattern, the second conductive layer including the data signal line 30, the source electrode 23, the drain electrode 24, and the first electrode 31, as shown in fig. 7 and 8, and fig. 8 is a cross-sectional view in A-A direction of fig. 7.

In an exemplary embodiment, the data signal lines 30 extend in a vertical direction, and the plurality of data signal lines 30 are parallel to each other. The plurality of scanning signal lines 20 extending in the horizontal direction and the plurality of data signal lines 30 extending in the vertical direction intersect each other to define a plurality of identification pixels arranged in a matrix.

In an exemplary embodiment, the source electrode 23, the drain electrode 24, and the first electrode 31 are disposed within at least one identification pixel, the source electrode 23 may be an integral structure connected to the data signal line 30, the drain electrode 24 is disposed opposite to the source electrode 23, an active layer between the source electrode 23 and the drain electrode 24 forms a channel region, and the first electrode 31 is connected to the drain electrode 24.

In an exemplary embodiment, the drain electrode 24 and the first electrode 31 may be of a unitary structure, i.e., the drain electrode of the thin film transistor simultaneously serves as the cathode of the PIN junction photodiode.

In an exemplary embodiment, the second metal thin film may be a metal material such as any one or more of silver (Ag), copper (Cu), aluminum (Al), titanium (Ti), and molybdenum (Mo), or an alloy material of the above metals such as aluminum neodymium alloy (AlNd) or molybdenum niobium alloy (MoNb), may be a single-layer structure, or a multi-layer composite structure such as Ti/Al/Ti, or the like.

To this end, a thin film transistor (Thin Film Transistor, abbreviated as TFT) as a switching device in the fingerprint recognition substrate is formed on the base, the thin film transistor including the gate electrode 21, the active layer 22, the source electrode 23, and the drain electrode 24.

(4) A second insulating layer pattern is formed. In an exemplary embodiment, forming the second insulating layer pattern may include: on the substrate with the patterns, a second insulating film is deposited, the second insulating film is patterned by a patterning process, a second insulating layer 12 covering the second conductive layer pattern is formed, a first via hole V1 is arranged on the second insulating layer 12, the first via hole V1 is located in the area where the first electrode 31 is located, the second insulating layer 12 in the first via hole V1 is etched away, and the surface of the first electrode 31 is exposed, as shown in fig. 9 and 10, and fig. 10 is a cross-sectional view in A-A direction in fig. 9.

(5) Forming a photoelectric conversion layer pattern. In an exemplary embodiment, forming the photoelectric conversion layer pattern may include: on the substrate on which the foregoing pattern is formed, a photoelectric conversion film is deposited, the photoelectric conversion film is patterned by patterning process to form a pattern of a photoelectric conversion layer 32, and the photoelectric conversion layer 32 is disposed on the first electrode 31 in the first via V1 and connected to the first electrode 31, as shown in fig. 11 and 12, fig. 12 is a cross-sectional view in A-A direction in fig. 11.

In the exemplary embodiment, the photoelectric conversion layer 32 includes a first doped layer, an intrinsic layer, and a second doped layer stacked as a main structure of the photodiode. The first doped layer can be P-type doped amorphous silicon (a-Si) or polysilicon (P-Si), and the second doped layer can be N-type doped amorphous silicon or polysilicon; or alternatively. The first doped layer may be N-type doped amorphous silicon or polysilicon, and the second doped layer may be P-type doped amorphous silicon or polysilicon.

In an exemplary embodiment, there is no overlapping area between the front projection of the photoelectric conversion layer 32 on the substrate and the front projection of the thin film transistor on the substrate.

(6) A planarization layer and a third insulating layer pattern are formed. In an exemplary embodiment, forming the planarization layer and the third insulating layer pattern may include: on the substrate on which the foregoing pattern is formed, a flat film is coated first, then a third insulating film is deposited, the third insulating film and the flat film are patterned by a patterning process to form a flat layer 13 covering the second insulating layer 12 and the photoelectric conversion layer 32 and a third insulating layer 14 provided on the flat layer 13, the third insulating layer 14 and the flat layer 13 are provided with second via holes V2, the second via holes V2 are located in the region of the photoelectric conversion layer 32, the third insulating layer 14 and the flat layer 13 in the second via holes V2 are removed, and the surface of the photoelectric conversion layer 32 is exposed as shown in fig. 13 and 14, and fig. 14 is a cross-sectional view in the direction A-A in fig. 13.

In the exemplary embodiment, the planarization layer 13 is used to planarize the film height difference caused by the photoelectric conversion layer 32, so as to avoid the process failure caused by excessive climbing of the subsequent film during the deposition process.

In an exemplary embodiment, the planarization layer may be made of a resin material, and the third insulating layer may be made of any one or more of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON), and may be a single layer, a multi-layer, or a composite layer.

(7) A second electrode pattern is formed. In an exemplary embodiment, forming the second electrode pattern may include: on the substrate on which the foregoing pattern is formed, a transparent conductive film is deposited, the transparent conductive film is patterned by a patterning process, and a second electrode 33 is formed on the third insulating layer 14, the second electrode 33 is connected to the positive electrode of the photoelectric conversion layer 32 through a second via V2, as shown in fig. 15 and 16, and fig. 16 is a cross-sectional view in A-A direction in fig. 15.

In an exemplary embodiment, the transparent conductive material may employ Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO).

To this end, a photodiode (Photo-Diode) as a photosensitive device in a fingerprint recognition substrate is formed on the base, and the PIN-type photodiode includes a first electrode 31, a photoelectric conversion layer 32, and a second electrode 33, and is used for photoelectrically converting incident light. In an exemplary embodiment, a thin film transistor as a switching device and a PIN type photodiode as a photosensitive device together constitute a fingerprint sensing layer of a fingerprint recognition substrate, and the thin film transistor controls readout of an electrical signal in the photodiode.

In an exemplary embodiment, the substrate has a thickness of about 120 μm to 150 μm and the fingerprint sensing layer has a thickness of about 3 μm to 5 μm.

(8) And forming a power line pattern. In an exemplary embodiment, forming the power line pattern may include: on the substrate on which the foregoing pattern is formed, a third metal thin film is deposited, and patterned by a patterning process, and a power line 34 is patterned on the second electrode 33, as shown in fig. 17 and 18, fig. 18 being a cross-sectional view in A-A direction of fig. 17.

In an exemplary embodiment, the power line 34 is directly connected to the second electrode 33, and the bias voltage supplied from the power line 34 is transmitted to the second electrode 33. Since the second electrode 33 is made of transparent conductive material and has a relatively high resistivity, the bias voltage provided by the power line 34 having a relatively low resistivity can ensure that each identification pixel of the fingerprint identification substrate has a uniform bias voltage, and can ensure uniformity of the identification performance of the fingerprint identification substrate.

In an exemplary embodiment, the orthographic projection of the power line 34 onto the substrate comprises an orthographic projection of the active layer channel region onto the substrate. The power line 34 is opaque, so that the light shielding layer can be used for preventing the channel region of the thin film transistor from generating larger leakage current due to illumination, and the electrical performance of the thin film transistor can be ensured.

In an exemplary embodiment, the third metal thin film may be a metal material such as any one or more of silver (Ag), copper (Cu), aluminum (Al), titanium (Ti), and molybdenum (Mo), or an alloy material of the above metals such as aluminum neodymium alloy (AlNd) or molybdenum niobium alloy (MoNb), may be a single-layer structure, or a multi-layer composite structure such as Ti/Al/Ti, or the like.

(9) Forming a photo hole layer pattern. In an exemplary embodiment, forming the light hole layer pattern may include: on the substrate on which the foregoing pattern is formed, a photo hole film is coated, the photo hole film is patterned by patterning process, a photo hole Layer (Aperture Layer) 41 is formed on the second electrode 33 in the second via hole, the photo hole Layer 41 includes a plurality of photo holes V3, the photo hole film in the photo hole is removed, and the surface of the second electrode 33 is exposed, as shown in fig. 19 and 20, fig. 20 is a cross-sectional view in A-A direction in fig. 19.

In an exemplary embodiment, the light hole layer 41 is used to form a light transmission channel, which may limit the optical path of light converged by the lens, and limit the irradiation of large-angle oblique light onto the photodiode, thereby reducing crosstalk.

In an exemplary embodiment, the photo hole layer 41 may employ a black organic photosensitive material having a high absorptivity, such as a photosensitive acrylic resin or a photosensitive polyester, or the like. The thickness of the photo hole layer 41 may be about 5 μm to 10 μm, and the aperture of the photo hole V3 may be about 3 μm to 8 μm, which can restrict light within a certain angle from being incident on the photodiode of the fingerprint sensing layer.

Note that, as shown in fig. 19 and 20, only 3×4 light holes are schematically shown, but in practice, the light holes of each identification pixel may be an array of light holes formed of several tens or several hundreds of light holes, and the cross-sectional shape of the light holes may be circular, elliptical, polygonal, or the like in a plane parallel to the display substrate.

(10) And forming a light modulation layer pattern. In an exemplary embodiment, forming the light modulation layer pattern may include: a light modulation film is coated on the substrate on which the above pattern is formed, and the light modulation film is patterned by patterning to form a pattern of the light modulation layer 42, as shown in fig. 21 and 22, and fig. 22 is a cross-sectional view in A-A direction in fig. 21.

In an exemplary embodiment, the light modulation layer 42 may not only provide a good plane for a subsequently formed lens layer, but may also be effective to cut off externally incident infrared light and may be formed by adjusting the thickness such that the focal point of each lens is located at the midpoint of the depth of the light hole.

(11) Forming a lens layer pattern. In an exemplary embodiment, forming the lens layer pattern may include: on the substrate on which the foregoing pattern is formed, a lens film is coated, and the lens film is patterned by a patterning process to form a pattern of a lens layer 43, as shown in fig. 1 and 2.

In an exemplary embodiment, the lens layer 43 includes a plurality of microlenses constituting a Microlens Array (micro Array) for converging reflected light of the fingerprint to play a role of light collection.

In an exemplary embodiment, the microlenses have a convex structure, and the focal point of at least one microlens is on the axis of at least one optical aperture (or the centerline of the optical channel) in a direction perpendicular to the substrate. In an exemplary embodiment, the light aperture may restrict light rays within ±θ2, i.e., light rays having an angle within ±θ2 from the normal to the plane in which the lens layer lies may reach the photodiode of the fingerprint sensing layer. The combination of the light aperture and the micro lens can restrict the light rays within the range of + -theta 1, and theta 1 is less than theta 2. In an exemplary embodiment, θ1 may be about 5 ° to 15 °.

In an exemplary embodiment, the material of the lens layer 43 may be a resin material or the like having a high transmittance, and a thickness of about 5 μm to 10 μm.

In an exemplary embodiment, the lens layer 43 may be implemented by a laser direct writing (Laser Direct Writing), nanoimprint (nanoimprint), resist Reflow (resin Reflow), or the like.

In an exemplary embodiment, the light modulation layer may employ an infrared cut-off material for cutting off infrared rays, preventing external rays from interfering with normal fingerprint imaging, on the one hand, and for providing a proper focal length for the lenses, on the other hand, such that the focal point of each lens is located at the midpoint of the depth of the light aperture. According to the embodiment of the disclosure, the optical modulation layer is arranged, so that the fingerprint identification substrate has the function of preventing strong light while the focal length of the lens is adjusted.

In an exemplary embodiment, the light modulation layer may be a reflective light modulation layer, and the reflective light modulation layer may include a plurality of first sub-layers and a plurality of second sub-layers, the first sub-layers having a refractive index different from that of the second sub-layers, the first sub-layers and the second sub-layers being alternately disposed to form the reflective light modulation layer of the laminated structure. For example, the material of the first sub-layer may be silicon oxide, and the material of the second sub-layer may be titanium oxide.

In an exemplary embodiment, the thickness of the reflective light modulation layer may be about 30 μm to 50 μm, and the actual thickness may be determined according to the focal length of the lens.

To this end, a collimation filter structure layer including a pupil layer, a light modulation layer and a lens layer is prepared, and the thickness of the collimation filter structure layer may be about 40 μm to 70 μm.

Fig. 23 is a transmittance curve of a reflective optical modulation layer according to an exemplary embodiment of the present disclosure. As shown in fig. 23, at a wavelength of about 600nm, the reflective optical modulation layer starts to cut off, so that the transmittance is very small, and external infrared light can be effectively reflected, so that crosstalk of optical signals caused by entering of the infrared light into an optical hole is avoided, and the requirement of the fingerprint product under the current screen on strong light prevention can be met.

In an exemplary embodiment, the light modulation layer may be an absorption type light modulation layer, and the absorption type light modulation layer may use a photosensitive resin having a higher transmittance in a blue-green band and a lower transmittance in an infrared band. For example, a blue-green photosensitive acrylic resin or the like may be used for the absorption-type light modulation layer.

In an exemplary embodiment, the thickness of the absorption-type light modulation layer may be about 30 μm to 50 μm, and the actual thickness may be determined according to the focal length of the lens.

Fig. 24 is a transmittance curve of an absorption-type light modulation layer according to an exemplary embodiment of the present disclosure. As shown in fig. 24, at a wavelength of about 600nm, the absorption type light modulation layer starts to cut off, the transmittance is very small, and external infrared light can be effectively absorbed, so that the crosstalk of optical signals caused by the fact that the infrared light enters a light hole is avoided, and the requirement of the fingerprint product under the current screen on strong light prevention can be met.

It should be noted that the foregoing description is merely an example of preparing the fingerprint recognition substrate, and the disclosure is not limited thereto. In actual implementation, the preparation process can be adjusted according to actual needs.

As can be seen from the structure and the preparation flow of the fingerprint identification substrate described above, the fingerprint identification substrate provided by the exemplary embodiment of the present disclosure integrates the collimating light path function and the light filtering function together to form the collimating light filtering structure layer including the light hole layer, the light modulation layer and the lens layer, and the light modulation layer between the light hole layer and the lens layer is utilized to realize the strong light prevention function and the lens focal length adjustment function, so that the thickness of the collimating light path light filtering structure is effectively reduced. According to the fingerprint identification substrate of the exemplary embodiment of the disclosure, the collimating light path filtering structure is directly prepared on the fingerprint sensing layer, so that the overall thickness of the fingerprint identification substrate is effectively reduced, the development trend of light and thin is met, the alignment precision in preparation is improved, and the product quality is improved. Compared with the stacking structure of optical glue, optical filter film, optical glue and collimation light path film adopted in the prior art, the overall thickness of the fingerprint identification substrate of the embodiment of the disclosure is about 160-220 μm, the overall thickness is reduced by about 30-40%, the space occupied by the fingerprint identification substrate in the display device is effectively reduced, the interference to the internal structure of the display device is reduced, and the fingerprint identification substrate has good application prospect. The fingerprint identification substrate provided by the disclosure has the advantages of high integration of functions, greatly simplified process, good compatibility with the existing preparation process, simple process implementation, easy implementation, high production efficiency, low production cost and high yield.

The present disclosure also provides a display device including the fingerprint recognition substrate of the foregoing exemplary embodiment. In an exemplary embodiment, the display device may include a fingerprint recognition substrate and an Organic Light-Emitting Diode (OLED) display substrate, and the fingerprint recognition substrate is attached to the back surface of the OLED display substrate through an optical adhesive, that is, the OLED display substrate is disposed on one side of a lens layer of the fingerprint recognition substrate. In an exemplary embodiment, the display device includes a plurality of display pixels, each of which is disposed in one-to-one correspondence with each of the identification pixels in a direction perpendicular to the substrate. When the fingerprint recognition device works, the OLED is used as a light source to emit light to the fingerprint, the reflection intensity of the fingerprint valley/ridge to the light is different, so that the light intensity emitted to the fingerprint recognition substrate is different, and the fingerprint lines are distinguished.

In an exemplary embodiment, the display device may be: any product or component with a display function such as a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a navigator, and the like, and the disclosure is not limited thereto.

The disclosure also provides a method for preparing the fingerprint recognition substrate, which is used for preparing the fingerprint recognition substrate of the foregoing exemplary embodiment. In an exemplary embodiment, a method of manufacturing a fingerprint recognition substrate may include:

Forming a fingerprint sensing layer on a substrate;

forming a light modulation layer on the light hole layer;

In an exemplary embodiment, the light modulation layer includes a reflective light modulation layer including at least one first sub-layer and a second sub-layer alternately disposed, the first sub-layer having a refractive index different from a refractive index of the second sub-layer.

In an exemplary embodiment, the light modulation layer includes an absorption type light modulation layer including a blue-green photosensitive acrylic resin.

The specific content of the preparation method of the fingerprint identification substrate of the present disclosure has been described in detail in the foregoing process of preparing the fingerprint identification substrate, and will not be described herein again.

According to the preparation method of the fingerprint identification substrate, the unthreaded hole layer, the optical modulation layer and the lens layer are integrated into the collimation filter structure layer, the optical modulation layer arranged between the unthreaded hole layer and the lens layer is used for cutting off external infrared light rays and adjusting the focal length of the lens in the lens layer, the thickness of the fingerprint identification substrate is effectively reduced, and the problem that the thickness of an existing fingerprint identification module is large is effectively solved. The preparation method of the fingerprint identification substrate greatly simplifies the process through high integration of functions, and the preparation process can be well compatible with the existing preparation process, and has the advantages of simple process implementation, easy implementation, high production efficiency, low production cost and high yield.

While the embodiments disclosed in this disclosure are described above, the embodiments are only used for facilitating understanding of the disclosure, and are not intended to limit the present invention. Any person skilled in the art will recognize that any modifications and variations can be made in the form and detail of the present disclosure without departing from the spirit and scope of the disclosure, which is defined by the appended claims.

Claims

1. The fingerprint identification substrate is characterized by comprising a substrate, a fingerprint sensing layer arranged on the substrate and a collimation filter structure layer arranged on one side of the fingerprint sensing layer far away from the substrate, wherein the fingerprint sensing layer comprises a thin film transistor and a photodiode which are arranged on the substrate, a second insulating layer arranged on one side of the thin film transistor far away from the substrate and a flat layer and a third insulating layer which are arranged on one side of the second insulating layer far away from the substrate, the thin film transistor comprises a gate electrode, an active layer, a source electrode and a drain electrode, the photodiode comprises a first electrode, a photoelectric conversion layer and a second electrode, the drain electrode of the thin film transistor is arranged on the same layer as the first electrode of the photodiode, a first through hole exposing the first electrode is arranged on the second insulating layer, the photoelectric conversion layer is connected with the first electrode through the first through hole, a second through hole exposing the photoelectric conversion layer is arranged on the flat layer and the third insulating layer, and the second through hole is arranged on the second insulating layer and is connected with the second electrode through the second through hole; the collimation filter structure layer comprises a light hole layer, a light modulation layer and a lens layer, wherein the light hole layer, the light modulation layer and the lens layer are sequentially arranged along the direction away from the substrate, the light hole layer is arranged on one side, away from the substrate, of the second electrode, the light hole layer comprises at least one light hole for forming a light transmission channel, and the light modulation layer is used for adjusting the focal length of the lens layer and cutting off infrared light.

2. The fingerprint recognition substrate of claim 1, wherein the fingerprint sensing layer further comprises a power line disposed on a side of the second electrode remote from the substrate, an orthographic projection of the power line on the substrate comprising an orthographic projection of a channel region of the thin film transistor on the substrate.

3. The fingerprint recognition substrate according to claim 1, wherein the thickness of the photo hole layer is 5 μm to 10 μm, and the aperture of the photo hole is 3 μm to 8 μm.

4. The fingerprint recognition substrate of claim 1, wherein the lens layer is disposed on a side of the light modulation layer remote from the base, the lens layer comprising at least one lens having a focal point located on an axis of the at least one light aperture.

5. The fingerprint recognition substrate according to claim 4, wherein the thickness of the lens layer is 5 μm to 10 μm.

6. The fingerprint recognition substrate according to any one of claims 1 to 5, wherein the light modulation layer comprises a reflective light modulation layer comprising at least one first sub-layer and a second sub-layer alternately arranged, the refractive index of the first sub-layer being different from the refractive index of the second sub-layer, the reflective light modulation layer having a thickness of 30 μm to 50 μm.

7. The fingerprint recognition substrate according to any one of claims 1 to 5, wherein the light modulation layer comprises an absorption type light modulation layer comprising a blue-green photosensitive acrylic resin, the absorption type light modulation layer having a thickness of 30 μm to 50 μm.

8. A display device comprising the fingerprint recognition substrate according to any one of claims 1 to 7.

9. The preparation method of the fingerprint identification substrate is characterized by comprising the following steps of:

forming a fingerprint sensing layer on a substrate; the fingerprint sensing layer comprises a thin film transistor and a photodiode which are arranged on the substrate, a second insulating layer which is arranged on one side of the thin film transistor far away from the substrate, and a flat layer and a third insulating layer which are arranged on one side of the second insulating layer far away from the substrate, wherein the thin film transistor comprises a gate electrode, an active layer, a source electrode and a drain electrode, the photodiode comprises a first electrode, a photoelectric conversion layer and a second electrode, the drain electrode of the thin film transistor and the first electrode of the photodiode are arranged on the same layer, a first via hole which exposes the first electrode is arranged on the second insulating layer, the photoelectric conversion layer is connected with the first electrode through the first via hole, the flat layer and the third insulating layer are provided with a second via hole which exposes the photoelectric conversion layer, the second electrode is arranged on the third insulating layer, and the second electrode is connected with the photoelectric conversion layer through the second via hole;

Forming a collimation filter structure layer on one side of the fingerprint sensing layer far away from the substrate; the collimation filter structure layer comprises a light hole layer, a light modulation layer and a lens layer, wherein the light hole layer, the light modulation layer and the lens layer are sequentially arranged along the direction away from the substrate, the light hole layer is arranged on one side, away from the substrate, of the second electrode, the light hole layer comprises at least one light hole for forming a light transmission channel, and the light modulation layer is used for adjusting the focal length of the lens layer and cutting off infrared light.

10. The method of manufacturing of claim 9, wherein forming a collimating filter structure layer on the fingerprint sensing layer comprises:

forming a light modulation layer on the light hole layer;

11. The method according to claim 10, wherein,

the light modulation layer comprises a reflective light modulation layer, the reflective light modulation layer comprises at least one first sub-layer and a second sub-layer which are alternately arranged, and the refractive index of the first sub-layer is different from that of the second sub-layer; or,