CN108694364A - A kind of fingerprint acquisition device and preparation method thereof - Google Patents

Abstract

Embodiments of the present invention provide a fingerprint collection device and a preparation method thereof, the device comprising: a base, a two-dimensional material array layer and a flexible protective layer connected sequentially from bottom to top; the base includes a substrate layer, a bottom electrode layer and an insulating array layer; two The three-dimensional material array layer is formed on the upper surface of the insulating array layer, and is connected to the bottom electrode layer through the through holes on the insulating array layer, and the bottom electrode layer and the two-dimensional material array layer are respectively electrically connected to the substrate to form multiple detection circuits. The method includes: forming a bottom electrode layer on the substrate layer, forming an insulating array layer with a plurality of through holes on the bottom electrode layer, forming a connecting electrode layer on one side of the through holes, forming a plurality of connecting electrode layers and the insulating array layer A two-dimensional material unit, two ends of the two-dimensional material unit are respectively connected to the connection electrode layer and the top electrode layer, and the bottom electrode layer and the top electrode layer are respectively electrically connected to the preset substrate; the surface of the device is covered with a flexible protective layer. The embodiments of the present invention improve the accuracy and efficiency of fingerprint identification.

Description

A fingerprint collection device and its preparation method

technical field

Embodiments of the present invention relate to the technical field of image acquisition, and in particular to a fingerprint acquisition device and a preparation method thereof.

Background technique

With the development of electronic information technology and the popularization of electronic products, the security of personal data and information in some electronic products (especially mobile phones and computers) has attracted more and more attention. Currently common verification methods include password verification, graphic verification, etc., that is, input a specific character string combination, or input a specific graphic into these electronic products. If the input value is the same as the predetermined value, the purpose of verifying the user's identity has been achieved.

In recent years, identity authentication methods such as biometrics have gradually emerged, that is, by detecting specific biological characteristics on a person, such as fingerprints, voiceprints, and irises, to identify the legitimacy of a user's identity. The current fingerprint identification technology is mainly divided into three types, optical detection, capacitance detection and ultrasonic detection. Optical detection obtains the grayscale image of the surface texture by irradiating light on the surface of the finger. Although this technology is relatively mature and cheap, the equipment is large in size and has high requirements for the cleanliness of the opponent; The grayscale image of the texture is obtained by different capacitance differences. This technology overcomes the defect of large volume of optical detection equipment and realizes the goal of integrating in smart phones. However, it still has high requirements for the cleanliness of fingers. Reliability is still not high; ultrasonic detection uses ultrasonic waves to generate different sizes of echoes at different material interfaces to detect the position of fingerprint ridges and valleys. This technology also has a small size, which reduces the impact on finger cleanliness to a certain extent. Requirements, but its acquisition time is relatively long, which reduces the efficiency of fingerprint identification.

Therefore, how to propose a solution that can achieve the accuracy and efficiency of fingerprint identification has become an urgent problem to be solved.

Contents of the invention

Aiming at the defects in the prior art, the embodiment of the present invention provides a fingerprint collection device and a preparation method thereof.

On the one hand, an embodiment of the present invention provides a fingerprint collection device, including:

The device includes: a substrate, a two-dimensional material array layer and a flexible protective layer arranged sequentially from bottom to top;

The base includes a substrate layer, a bottom electrode layer and an insulating array layer arranged sequentially from bottom to top, and a plurality of through holes are arranged on the insulating array layer;

The two-dimensional material array layer is formed on the side of the insulating array layer away from the bottom electrode layer, and connected to the bottom electrode layer through the through hole, the bottom electrode layer and the two-dimensional material array layer are respectively electrically connected to the substrates outside the device to form a plurality of detection circuits;

The detection circuit is used to collect resistance changes corresponding to different deformations of the two-dimensional material array layer due to pressure, so as to obtain grayscale images of fingerprint lines.

Further, the two-dimensional material array layer includes a connection electrode layer, a top electrode layer and a two-dimensional material layer, the connection electrode layer is connected to the bottom electrode layer through the through hole, and the connection electrode layer is connected to the bottom electrode layer. A gap is left between the side walls of the through holes;

The two-dimensional material layer includes a plurality of two-dimensional material units, and the plurality of two-dimensional material units are formed on the side of the connecting electrode layer and the insulating array layer away from the bottom electrode layer, and the two-dimensional material One end of the unit is connected to the connection electrode layer, the other end is connected to the top electrode layer, the top electrode layer is electrically connected to the substrate outside the device, and the top electrode layer and the bottom electrode layer constitute a plurality of the detection circuit.

Further, the two-dimensional material unit covers above the through hole or the upper surface of the connecting electrode layer and the insulating array layer.

Further, the bottom electrode layer is strip-shaped formed on the upper surface of the substrate layer, and correspondingly, the through holes on the insulating array layer are arranged at positions corresponding to the bottom electrode layer.

Further, the upper surface of the insulating array layer is shaped into strips of the top electrode layer, and the top electrode layer is arranged to cross the bottom electrode layer; each strip-shaped bottom electrode and each strip-shaped top electrode are electrically connected to the external substrate connected, the substrate includes a control circuit, and the control circuit is used to scan each strip-shaped bottom electrode and strip-shaped top electrode to form a plurality of detection circuits.

On the other hand, an embodiment of the present invention provides a method for manufacturing a fingerprint collection device, including:

forming a bottom electrode layer on the upper surface of the selected substrate layer;

forming an insulating array layer on the upper surface of the bottom electrode layer, and setting a plurality of through holes on the upper surface of the insulating array layer;

forming a connection electrode layer on one side of the through hole, so that the connection electrode layer is connected to the bottom electrode layer;

A plurality of two-dimensional material units are formed on the upper surface of the connecting electrode layer and the insulating array layer, one end of the two-dimensional material unit is connected to the connecting electrode layer, and the other end is connected to the top electrode layer, and the top electrode layer is and the bottom electrode layer are electrically connected to a preset substrate to form a plurality of detection circuits;

A flexible protective layer is covered on the upper surfaces of the two-dimensional material unit, the top electrode layer and the insulating array layer.

Further, the formation of the bottom electrode layer on the surface of the selected substrate layer includes:

A series of strip-shaped electrodes are sputtered on the substrate layer as the bottom electrode layer after patterning with a hard mask as a template or by photolithography.

Further, the setting of through holes on the surface of the insulating array layer includes:

Patterning by photolithography or using a hard mask as a template, using dry etching or wet etching, etches an array of micron-scale through holes on the surface of the insulating array layer, the through holes The location is on the strip-shaped bottom electrode layer.

Further, forming the connection electrode layer on one side of the through hole so as to connect the connection electrode layer to the bottom electrode layer includes:

Patterning is performed by photolithography to expose one side of the through hole, and the photoresist is stripped off by sputtering, deposition or evaporation to form the connecting electrode layer on one side of the through hole.

Further, forming a plurality of two-dimensional material units on the surface of the connecting electrode layer and the insulating array layer includes:

transferring a large sheet of two-dimensional material to the upper surface of the connecting electrode layer and the insulating array layer by dry method or wet method;

patterning by photolithography, protecting the two-dimensional material connected to the connection electrode layer on the through hole or on the side of the through hole, and then etching to remove the unprotected two-dimensional material, A two-dimensional material layer is formed.

The fingerprint collection device and its preparation method provided by the embodiments of the present invention can realize fast collection of fingerprint images, and reduce the influence of water, oil and other pollutants attached to the skin on fingerprint image collection and fingerprint recognition accuracy, and improve fingerprint recognition accuracy. recognition accuracy and efficiency.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 is a schematic structural view of a fingerprint collection device in an embodiment of the present invention;

2 is a schematic structural diagram of another fingerprint collection device in an embodiment of the present invention;

FIG. 3 is a schematic plan view of a hole-type fingerprint collection device in an embodiment of the present invention;

FIG. 4 is a schematic diagram of the planar structure of a planar fingerprint collection device in an embodiment of the present invention;

Fig. 5 is a schematic flow chart of a manufacturing method of a fingerprint collection device in an embodiment of the present invention;

6 is a schematic flow chart of a method for preparing a hole-type fingerprint collection device in an embodiment of the present invention;

Fig. 7 is a schematic flowchart of a method for preparing a planar fingerprint collection device in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Fig. 1 is a schematic structural diagram of a fingerprint collection device in an embodiment of the present invention. As shown in Fig. 1, the fingerprint collection device provided by the embodiment of the present invention includes:

The substrate 10, the two-dimensional material array layer 20 and the flexible protective layer 30 are sequentially connected from bottom to top;

The substrate 10 includes a substrate layer 11, a bottom electrode layer 12, and an insulating array layer 13 sequentially connected from bottom to top, and the insulating array layer 13 is provided with a plurality of through holes 14;

The two-dimensional material array layer 20 is formed on the side of the insulating array layer 13 away from the bottom electrode layer, and connected to the bottom electrode layer 12 through the through hole 14, the bottom electrode layer 12 and the bottom electrode layer The two-dimensional material array layer 20 is respectively electrically connected to the substrate outside the device to form a plurality of detection circuits;

The detection circuit is used to collect resistance changes corresponding to different deformations of the two-dimensional material array layer 20 due to pressure, so as to obtain grayscale images of fingerprint lines.

Specifically, as shown in FIG. 1, the substrate layer 11, the bottom electrode layer 12, and the insulating array layer 13 connected sequentially from bottom to top form a base, and a plurality of through holes 14 are arranged on the insulating array layer 13, wherein the through holes 14 The shape can be cylindrical, square or other shapes, which are not specifically limited in this embodiment of the present invention. The two-dimensional material array layer 20 is disposed on the upper surface of the insulating array layer 13 and connected to the bottom electrode layer 12 through the through hole 14 . The bottom electrode layer 12 and the two-dimensional material array layer 20 are respectively electrically connected to the substrate located outside the fingerprint collection device with lead wires to form a detection circuit, wherein the bottom electrode layer 12 and the two-dimensional material array layer 20 can form multiple detection circuits to obtain multiple detection circuits. In each detection circuit, the two-dimensional material array layer 20 undergoes different pressures to produce resistance changes corresponding to different deformations, and a grayscale image of the fingerprint pattern is further obtained. A very thin flexible protective layer 30 is provided on the top surface of the two-dimensional material array layer 20 and the substrate 10 , that is, the upper surface of the fingerprint collection device. Among them: the material of the substrate layer 11 can be selected from Si, Si/SiO ₂ , Si/HfO ₂ , Si/Al ₂ O ₃ , Si/MgO, Si/TiO ₂ , Si/SiN _x and other silicon-based substrates, Mica (mica Ore), diamond, SiC (corundum), sapphire, quartz, glass, etc. can also be used as substrates, or flexible substrates PI (plastic material, commonly known as polyimide in Chinese), PET (polyester resin), PDMS (polyester resin) Dimethicone), rubber, etc. The bottom electrode layer 12 can be made of Au, and the insulating array layer 13 can be made of SiO ₂ , HfO ₂ , TiO ₂ , Al ₂ O ₃ , MgO. These insulating array layers are characterized by being thin and difficult to deform; the insulating array layer 13 can also be Organic insulating layers such as parylene and PDMS, this insulating array layer is characterized by thinness and softness, and can follow the same deformation when the two-dimensional material is deformed. The two-dimensional material array layer 20 can be selected from graphene or other two-dimensional materials with good piezoresistive properties such as tungsten sulfide, black phosphorus, etc. The two-dimensional material refers to the non-nanoscale (1- 100nm) materials that move freely (planar motion), such as nanofilms, superlattices, and quantum wells. The flexible protective layer 30 can be selected from PDMS, PVA (polyvinyl alcohol), PMMA (polymethyl methacrylate), photoresist, parylene and the like.

The fingerprint pattern is divided into ridges and valleys. When the finger presses the flexible protective layer 30, the pressure on the two-dimensional material array layer 20 under the flexible protective layer 30 corresponding to the ridges and valleys is different, and the deformation is also different. different resistance changes. It is even possible that the resistance of the two-dimensional material array layer 20 corresponding to the ridges changes, but the resistance of the two-dimensional material array layer 20 corresponding to the valleys does not change. Therefore, a large array of two-dimensional material piezoresistive devices can be used to electrically connect the above-mentioned fingerprint collection device to the corresponding substrate, and the grayscale image of the fingerprint pattern can be detected through the detection circuit for subsequent feature comparison to realize fingerprint recognition. purpose of identification. In addition, pressure sensing can reduce the impact of moisture, oil and other pollutants attached to the skin on the accuracy of fingerprint recognition. Because when the finger is pressed, these pollutants will be squeezed into the valley of the fingerprint, and due to its fluidity, it will not cause a force close to the pressure of the fingerprint ridge on the two-dimensional material pressure sensor at the position of the valley, which also reduces The probability that the location of the contaminant is detected as a ridge. At the same time, since the piezoresistive effect is a transient effect, it may also exceed the ultrasonic detection method in terms of response speed.

The fingerprint collection device provided by the embodiment of the present invention can realize the rapid collection of fingerprint images, and reduces the influence of pollutants such as moisture and oil attached to the skin on the collection of fingerprint images and the accuracy of fingerprint recognition, and improves the accuracy of fingerprint recognition and efficiency.

On the basis of the above embodiments, the two-dimensional material array layer includes a connection electrode layer, a top electrode layer and a two-dimensional material layer, the connection electrode layer is connected to the bottom electrode layer through the through hole, and the There is a gap between the connecting electrode layer and the sidewall of the through hole;

The two-dimensional material layer includes a plurality of two-dimensional material units, and the plurality of two-dimensional material units are formed on the side of the connecting electrode layer and the insulating array layer away from the bottom electrode layer, and the two-dimensional material One end of the unit is connected to the connection electrode layer, the other end is connected to the top electrode layer, the top electrode layer is electrically connected to the substrate outside the device, and the top electrode layer and the bottom electrode layer constitute a plurality of the detection circuit.

Specifically, as shown in FIG. 1, the two-dimensional material array layer 20 includes a connection electrode layer 21, a top electrode layer 22 and a two-dimensional material layer 23, wherein the connection electrode layer 21 is connected to the bottom electrode layer 12 through a through hole 14, and As shown in Figure 1, there is a certain gap between the connection electrode layer 21 and a side wall of the through hole 14, that is, the through hole 14 is not filled by the connection electrode layer, and there is a gap between the two-dimensional material layer and the bottom electrode layer. The void, that is, where the through hole 14 is located, can provide a space for the deformation of the two-dimensional material layer 23 . The two-dimensional material layer 23 includes a plurality of two-dimensional material units 231. As shown in FIG. On the upper surface of the connection electrode layer 21 and the insulating array layer 13 . In addition, one end of the two-dimensional material unit 231 is connected to the connection electrode layer 21, and the other end is connected to the top electrode layer 22. The top electrode layer 22 and the bottom electrode layer 12 are respectively electrically connected to the substrate outside the device to form a plurality of detection circuits, so as to realize the present When the two-dimensional material is deformed due to pressure, the change of its resistance value is detected, and the grayscale image of the fingerprint is collected.

Based on the above embodiments, the two-dimensional material unit covers the through hole or the upper surface of the connecting electrode layer and the insulating array layer.

Specifically, as shown in FIG. 1 , the two-dimensional material unit 231 is completely covered above the through hole 14. Of course, the two-dimensional material unit 231 can also cover the insulating array layer 13 and the connection other than the through hole 14 as required. The upper surface of the electrode layer 21. Figure 2 is a schematic structural view of another fingerprint collection device in an embodiment of the present invention, as shown in Figure 2, the structural difference between Figure 2 and the fingerprint collection device in Figure 1 is that the positions covered by the two-dimensional material unit 231 are different, as shown in Figure 1 The two-dimensional material unit 231 completely covers the through hole 14 . In FIG. 2 , the two-dimensional material unit 231 covers the upper surface of the insulating array layer 13 and the connection electrode layer 21 outside the through hole 14 . It should be _noted that the material used for the _{insulating array layer 13} in FIG. On the hole 14, the through hole 14 is used to provide the space required for the deformation of the two-dimensional material. The material used in the insulating array layer 13 in FIG. 2 is a flexible and easily deformable material, such as parylene, PDMS, etc., and the two-dimensional material unit 231 is covered on the insulating array layer 13 outside the through hole 14 and the connecting electrode layer 21. On the upper surface, the flexible material used in the insulating array layer 13 provides space for the two-dimensional material to deform.

On the basis of the above embodiments, the bottom electrode layer is strip-shaped formed on the upper surface of the substrate layer, and correspondingly, the through holes on the insulating array layer are arranged at positions corresponding to the bottom electrode layer .

Specifically, the bottom electrode layer 12 is arranged in stripes on the upper surface of the substrate layer 11, that is, the upper surface of the substrate layer 11 is not completely covered with the bottom electrode layer 12, and a plurality of strip-shaped bottom electrodes are arranged on the upper surface of the substrate layer 11 to form bottom electrode layer. At this time, the through holes 14 on the insulating array layer 13 are arranged at positions corresponding to the strip-shaped bottom electrode layer 12, so that each strip-shaped bottom electrode has a plurality of through holes corresponding to each other, so that the bottom electrode layer 12 and the two The dimensional material array layer 20 is connected.

On the basis of the above embodiment, the top electrode layer is strip-shaped on the upper surface of the insulating array layer, and the top electrode layer and the bottom electrode layer are arranged to cross;

Each strip-shaped bottom electrode and each strip-shaped top electrode are electrically connected to an external substrate, and the substrate includes a control circuit for scanning each strip-shaped bottom electrode and strip-shaped top electrode to form a plurality of strip-shaped bottom electrodes and strip-shaped top electrodes. The detection circuit described above.

Specifically, the top electrode layer 22 is strip-shaped on the upper surface of the insulating array layer 13, and a plurality of strip-shaped top electrodes are arranged on the upper surface of the insulating array layer 13 to form the top electrode layer 22, and the top electrode layer 22 crosses the bottom electrode layer 12. Setting, that is, the arrangement directions of the top electrode layer 22 and the bottom electrode layer 12 are different, so as to form an electrode scanning array. In actual application, each strip-shaped bottom electrode and strip-shaped top electrode are connected to the external substrate, and the external substrate has a control circuit, which can realize scanning of each strip-shaped bottom electrode and strip-shaped top electrode, forming a multi- Each detection loop is used to obtain the resistance change in each detection loop to obtain the grayscale image of the fingerprint.

Fig. 3 is a schematic plan view of a hole-type fingerprint collection device in an embodiment of the present invention, and Fig. 4 is a plan view of a planar fingerprint collection device in an embodiment of the present invention. Fig. 3 corresponds to a plan view of Fig. 1, and Fig. 4 corresponds to 2 is a schematic plan view. The embodiment of the present invention distinguishes hole-type and planar-type fingerprint collection devices mainly by whether the through holes are all covered by a two-dimensional material layer. If so, it is a hole-type fingerprint collection device, otherwise it is a planar fingerprint collection device. device. As shown in Figure 3, a bottom electrode layer 12 distributed in strips is arranged on the upper surface of the substrate layer 11, an insulating array layer 13 is arranged on the upper surface of the bottom electrode layer 12, and a two-dimensional material layer is arranged on the upper surface of the insulating array layer 13. 23 and the top electrode layer 22 arranged in strips, the through hole 14 in FIG. 3 is completely covered by the two-dimensional material layer 23 . As shown in FIG. 4 , the difference between FIG. 4 and FIG. 3 is that the through hole 14 in FIG. 4 is not completely covered by the two-dimensional material layer 23 . It can be seen from Fig. 3 and Fig. 4 that the bottom electrode layer 12 and the top electrode layer 22 in the embodiment of the present invention are vertically arranged, that is, a kind of intersecting arrangement. In practical application, the intersecting angle can be set as required. Examples are not specifically limited.

The fingerprint acquisition device provided by the embodiment of the present invention uses the piezoresistive characteristics of two-dimensional semiconductor materials in fingerprint identification technology, reasonably sets the structure of the piezoresistive sensor fingerprint acquisition device, and uses the piezoresistive sensor as the basic unit of fingerprint identification for fingerprint identification. The grayscale image of the fingerprint is then compared with the subsequent features to realize a new type of fingerprint identification with higher accuracy and faster speed, which improves the accuracy and efficiency of fingerprint identification.

Fig. 5 is a schematic flow chart of a preparation method of a fingerprint collection device in an embodiment of the present invention. As shown in Fig. 5, the preparation process of the fingerprint collection device provided by the embodiment of the present invention includes:

S1, forming a bottom electrode layer on the upper surface of the selected substrate layer;

S2, forming an insulating array layer on the upper surface of the bottom electrode layer, and setting a plurality of through holes on the upper surface of the insulating array layer;

S3. Form a connection electrode layer on one side of the through hole, so that the connection electrode layer is connected to the bottom electrode layer;

S4. Form a plurality of two-dimensional material units on the upper surface of the connecting electrode layer and the insulating array layer, one end of the two-dimensional material unit is connected to the connecting electrode layer, and the other end is connected to the top electrode layer, and the top The electrode layer and the bottom electrode layer are electrically connected to a preset substrate to form multiple detection circuits;

S5. Covering a flexible protective layer on the upper surfaces of the two-dimensional material unit, the top electrode layer and the insulating array layer.

Specifically, in the manufacturing method of the fingerprint collection device provided by the embodiment of the present invention, firstly, an appropriate substrate layer is selected, and the selection of the specific material is consistent with the above-mentioned embodiment, and will not be repeated here. After selecting a _suitable substrate layer, clean the substrate layer. Different cleaning methods can be selected according to the substrate layer of different materials. Hydrogen oxide=7:3) rinse with deionized water and blow dry with high-purity nitrogen after soaking, organic flexible substrates such as PI or PET can be ultrasonically cleaned with organic solvents such as acetone, methanol, isopropanol, alcohol, etc. Blow dry with pure nitrogen. The upper surface of the cleaned substrate layer is covered with metal to form a bottom electrode layer, an insulating array layer is arranged on the upper surface of the bottom electrode layer, and a plurality of through holes are arranged on the surface of the insulating array layer. A connection electrode layer is formed on one side of the through hole on the surface of the insulating array layer, so that the connection electrode layer is connected to the bottom electrode through the through hole. A plurality of two-dimensional material units are formed on the upper surface of the connecting electrode layer and the insulating array layer to form a two-dimensional material layer, wherein one end of the two-dimensional material unit is connected to the connecting electrode layer, and the other end is connected to the top electrode layer. The top electrode layer and the bottom electrode layer are electrically connected to the preset substrate to form multiple detection circuits to detect the resistance change of the two-dimensional material layer, and further obtain the grayscale image of the fingerprint pattern. After the various structural layers of the fingerprint collection device are arranged, a flexible protective layer is formed on the upper surface of the fingerprint collection device to protect the fingerprint collection device.

The preparation method of the fingerprint collection device provided by the embodiment of the present invention has a simple implementation process and the prepared fingerprint collection device is reliable and has strong applicability, so that the fingerprint collection device prepared by the method can realize the rapid collection of fingerprint images, Moreover, the influence of water, oil and other pollutants attached to the skin on the fingerprint image collection and fingerprint identification accuracy is reduced, and the accuracy and efficiency of fingerprint identification are improved.

On the basis of the above embodiments, the formation of the bottom electrode layer on the surface of the selected substrate layer includes:

A series of strip-shaped electrodes are sputtered on the substrate layer as the bottom electrode layer after patterning with a hard mask as a template or by photolithography.

Specifically, a strip-shaped bottom electrode layer is formed on the upper surface of the substrate layer. Specifically, a series of strip-shaped electrodes can be sputtered as the bottom electrode layer after patterning with a hard mask as a template or by photolithography. . The shape of the template and the patterned shape of the photolithography technology can be selected according to needs, which are not specifically limited in the embodiment of the present invention.

On the basis of the above embodiments, the setting of through holes on the surface of the insulating array layer includes:

Patterning by photolithography or using a hard mask as a template, using dry etching or wet etching, etches an array of micron-scale through holes on the surface of the insulating array layer, the through holes The location is on the strip-shaped bottom electrode layer.

Specifically, after the bottom electrode layer is formed, an insulating array layer is deposited on the bottom electrode layer, and the selection of the material of the insulating array layer is consistent with the above-mentioned embodiments, and will not be repeated here. After the insulating array layer is formed, a plurality of through holes need to be provided on the insulating array layer to realize the connection between the two-dimensional material array layer and the bottom electrode layer. The setting method of the through holes can be: patterning by photolithography or using a hard mask as a template, using dry etching or wet etching (selecting dry etching or wet etching according to the material of the insulating array layer) ), etching a plurality of micron-scale through holes in an array on the surface of the insulating array layer, wherein the positions of the plurality of through holes are located on the strip-shaped bottom electrode layer. The shape of the template and the patterned shape of the photolithography technology can be selected according to needs, which are not specifically limited in the embodiment of the present invention. Among them, the etchant of dry etching is plasma, which uses plasma to react with the surface film to form volatile substances, or directly bombards the surface of the film to be corroded; wet etching uses chemical etching solution The chemical reaction with the etched substance will corrode the etching method.

On the basis of the above embodiments, the formation of the connection electrode layer on one side of the through hole so as to connect the connection electrode layer to the bottom electrode layer includes:

Patterning is performed by photolithography to expose one side of the through hole, and the photoresist is stripped off by sputtering, deposition or evaporation to form the connecting electrode layer on one side of the through hole.

Specifically, after the through holes of the insulating array layer are set, patterning is carried out by photolithography, one side of each through hole is exposed, and metal is injected into one side of the through hole by sputtering, deposition or evaporation to form an electrode, and then The photoresist is peeled off, and a connection electrode layer is formed on one side of each through hole. That is, cover a part of the volume of each through hole as required, and form an electrode on the exposed side of the through hole by sputtering, deposition or evaporation techniques, that is, a connection electrode layer, and the connection electrode layer is connected to the bottom electrode layer. The specific volume of the exposed through hole can be set according to needs, and is not specifically limited in this embodiment of the present invention. Or, it is also possible to make a layer of metal on the insulating array with through holes as an electrode, and then use photolithography to pattern it, and then etch the required parts with photoresist protection, and then photoresist Remove to achieve the same purpose.

On the basis of the above embodiments, the formation of multiple two-dimensional material units on the surface of the connecting electrode layer and the insulating array layer includes:

transferring a large sheet of two-dimensional material to the upper surface of the connecting electrode layer and the insulating array layer by dry method or wet method;

patterning by photolithography, protecting the two-dimensional material connected to the connection electrode layer on the through hole or on the side of the through hole, and then etching to remove the unprotected two-dimensional material, A two-dimensional material layer is formed.

Specifically, after the substrate layer, the bottom electrode layer, the connecting electrode layer and the insulating array layer are arranged, a large piece of two-dimensional material such as graphene is transferred to the upper surface of the connecting electrode layer and the insulating array layer by dry method or wet method. Then patterning is carried out by photolithography to protect the two-dimensional material connected to the connection electrode layer on the through hole or on the side of the through hole, and then etch to remove the unprotected two-dimensional material to form a two-dimensional material layer. That is, the two-dimensional material layer covers the through hole or the insulating array layer except the through hole, as shown in Figure 1, the two-dimensional material above the through hole is protected, and other two-dimensional materials are removed, so that the through hole is completely covered by two-dimensional Material layer covering; as shown in Figure 2, protect the two-dimensional material on the insulating array layer outside the through hole, remove the two-dimensional material above the through hole, so that the two-dimensional material covers the insulating array layer outside the through hole.

Fig. 6 is a schematic flow chart of the preparation method of the hole-type fingerprint collection device in the embodiment of the present invention. As shown in Fig. 6, the specific flow of the fingerprint collection device in the embodiment of the present invention is as follows:

Step 61. Select a Si wafer with a 300nm thermal oxygen layer as the substrate layer, use a hard mask as a template, and deposit Cr/Au with a thickness of 50nm by magnetron sputtering as a buffer layer and a bottom electrode layer to improve the electrode and substrate layer. The combination between the bottom layers is specifically shown in (1) in FIG. 6 .

Step 62, use ALD (Atomic layer deposition, atomic layer deposition) to deposit 80nmHfO ₂ on the surface as an insulating array layer, and use CMP (Chemical mechanical polishing/planarization, chemical mechanical polishing) to smooth it, as shown in (2) in Figure 6 .

Step 63, using photolithography and dry etching to form a 10 μm*10 μm through hole on the insulating array layer HfO ₂ , as shown in (3) in FIG. 6 .

Step 64, use the hard mask as a template, align one side of the through hole, and deposit 50nm Au as the connecting electrode layer connecting the bottom electrode layer by magnetron sputtering, as shown in (4) in FIG. 6 .

Step 65, wet transfer transfer large single-layer graphene to the silicon wafer, specifically as shown in (5) in Figure 6 .

Step 66, using photolithography and dry etching to form small pieces of 15 μm*15 μm on the graphene to cover the through holes to form a two-dimensional material layer, as shown in (6) in FIG. 6 .

Step 67, using the hard mask as a template, align the side of the two-dimensional material layer without electrodes, and deposit 50nm Cr/Au as a buffer layer and top electrode layer by magnetron sputtering, as shown in (7) in Figure 6 .

Step 68. Finally, a layer of PDMS is used as a flexible protective layer by spin coating, as shown in (8) in FIG. 6 , and the fingerprint collection device is finally prepared.

Fig. 7 is a schematic flow chart of the preparation method of the planar fingerprint collection device in the embodiment of the present invention. As shown in Fig. 7, the specific flow of the fingerprint collection device in the embodiment of the present invention is as follows:

Step 71. Select a Si wafer with a 300nm thermal oxygen layer as the substrate layer, use a hard mask as a template, and deposit Cr/Au with a thickness of 50nm by magnetron sputtering as a buffer layer and a bottom electrode layer to improve the electrode and substrate layer. The combination between the bottom layers is specifically shown in (1) in FIG. 7 .

Step 72, using a spin-coating method to cast a layer of 80nm parylene as an insulating layer, and smoothing it out, as shown in (2) in FIG. 7 .

Step 73, using photolithography and dry etching to form a 10 μm*10 μm via hole on the insulating array layer HfO ₂ , as shown in (3) in FIG. 7 .

Step 74 , use the hard mask as a template, align one side of the through hole, and deposit 50nm Au by magnetron sputtering as the connecting electrode layer connecting the bottom electrode layer, as shown in (4) in FIG. 7 .

Step 75, wet transfer transfer large single-layer graphene to the silicon wafer, specifically as shown in (5) in Figure 7.

Step 76, using photolithography and dry etching to form a small piece of 15 μm*15 μm on the graphene to cover the connecting electrode layer and the parylene insulating array layer to form a two-dimensional material layer, as shown in (6) in Figure 7 shown.

Step 77, using the hard mask as a template, align the side of the two-dimensional material layer without electrodes, and deposit 50nm Cr/Au as a buffer layer and top electrode layer by magnetron sputtering, as shown in (7) in Figure 7 .

Step 78. Finally, a layer of PDMS is used as a flexible protective layer by spin coating, as shown in (8) in FIG. 7 .

It can be seen that the difference between FIG. 6 and FIG. 7 lies in that the material of the insulating array layer is different, which correspondingly results in a different coverage of the two-dimensional material layer. The material used for the insulating array layer in FIG. 6 is a hard material that is not easily deformed. By covering the through hole with a two-dimensional material layer, the through hole is used to provide the space required for deformation of the two-dimensional material. The material used in the insulating array layer in Figure 7 is a flexible and easily deformable material. The two-dimensional material layer covers the upper surface of the insulating array layer and the connecting electrode layer outside the through holes. The flexible material used in the insulating array layer is a two-dimensional material. Provides the space needed for deformation. In addition, the electrode width and thickness, the thickness of the insulating array layer, and the side length of the graphene sheet in the embodiment of the present invention can all be designed according to requirements, so as to reduce the volume of the fingerprint collection device and improve the performance of the fingerprint collection device.

It should be noted that graphene is selected as the two-dimensional material in the embodiment of the present invention, because graphene has the characteristic that its resistivity changes with stress under stress such as pressure and tension. Moreover, the suspended graphene can be stretched under the pressure of the needle tip. When the stretching amount reaches about 3%, there is already about 5% resistance change, and the graphene can withstand a maximum in-plane tensile stress of about 25%. , such a large stress intensity is sufficient to generate a very large resistance change for circuit detection. Of course, other two-dimensional materials, such as tungsten sulfide, black phosphorus, etc., can also be selected to prepare the fingerprint collection device as required.

The preparation method of the fingerprint collection device provided by the embodiment of the present invention has simple process and convenient operation. The prepared fingerprint collection device has strong anti-interference, fast collection speed, small size, and can quickly and accurately collect the grayscale image of the fingerprint, further improving the fingerprint collection device. The accuracy and efficiency of fingerprint recognition are improved.

The device embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in One place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without any creative efforts.

Claims (10)

1. A fingerprint collection device, characterized in that said device comprises: The substrate, the two-dimensional material array layer and the flexible protective layer are arranged sequentially from bottom to top; The base includes a substrate layer, a bottom electrode layer and an insulating array layer arranged sequentially from bottom to top, and a plurality of through holes are arranged on the insulating array layer; The two-dimensional material array layer is formed on the side of the insulating array layer away from the bottom electrode layer, and connected to the bottom electrode layer through the through hole, the bottom electrode layer and the two-dimensional material array layer are respectively electrically connected to the substrates outside the device to form a plurality of detection circuits; The detection circuit is used to collect resistance changes corresponding to different deformations of the two-dimensional material array layer due to pressure, so as to obtain grayscale images of fingerprint lines. 2. The device according to claim 1, wherein the two-dimensional material array layer comprises a connection electrode layer, a top electrode layer and a two-dimensional material layer, and the connection electrode layer is connected to the bottom through the through hole. The electrode layers are connected, and there is a gap between the connecting electrode layer and the sidewall of the through hole; The two-dimensional material layer includes a plurality of two-dimensional material units, and the plurality of two-dimensional material units are formed on the side of the connecting electrode layer and the insulating array layer away from the bottom electrode layer, and the two-dimensional material One end of the unit is connected to the connection electrode layer, the other end is connected to the top electrode layer, the top electrode layer is electrically connected to the substrate outside the device, and the top electrode layer and the bottom electrode layer constitute a plurality of the detection circuit. 3 . The device according to claim 2 , wherein the two-dimensional material unit covers above the through hole or the upper surfaces of the connecting electrode layer and the insulating array layer. 4 . 4. The device according to claim 2, characterized in that, the bottom electrode layer is strip-shaped formed on the upper surface of the substrate layer, and correspondingly, the through holes on the insulating array layer are arranged in the same position as the The position corresponding to the bottom electrode layer. 5. The device according to claim 4, wherein the top electrode layer is strip-shaped on the upper surface of the insulating array layer, and the top electrode layer and the bottom electrode layer are arranged crosswise; Each strip-shaped bottom electrode and each strip-shaped top electrode are electrically connected to an external substrate, and the substrate includes a control circuit for scanning each strip-shaped bottom electrode and strip-shaped top electrode to form a plurality of strip-shaped bottom electrodes and strip-shaped top electrodes. The detection circuit described above. 6. A preparation method of a fingerprint collection device, characterized in that the method comprises: forming a bottom electrode layer on the upper surface of the selected substrate layer; forming an insulating array layer on the upper surface of the bottom electrode layer, and setting a plurality of through holes on the upper surface of the insulating array layer; forming a connection electrode layer on one side of the through hole, so that the connection electrode layer is connected to the bottom electrode layer; A plurality of two-dimensional material units are formed on the upper surface of the connecting electrode layer and the insulating array layer, one end of the two-dimensional material unit is connected to the connecting electrode layer, and the other end is connected to the top electrode layer, and the top electrode layer is and the bottom electrode layer are electrically connected to a preset substrate to form a plurality of detection circuits; A flexible protective layer is covered on the upper surfaces of the two-dimensional material unit, the top electrode layer and the insulating array layer. 7. The method according to claim 6, wherein said forming a bottom electrode layer on the selected substrate layer surface comprises: A series of strip-shaped electrodes are sputtered on the substrate layer as the bottom electrode layer after patterning with a hard mask as a template or by photolithography. 8. The method according to claim 7, wherein the setting of through holes on the surface of the insulating array layer comprises: Patterning by photolithography or using a hard mask as a template, using dry etching or wet etching, etches an array of micron-scale through holes on the surface of the insulating array layer, the through holes The location is on the strip-shaped bottom electrode layer. 9. The method according to claim 6, wherein the forming a connection electrode layer on one side of the through hole so that the connection electrode layer is connected to the bottom electrode layer comprises: Patterning is performed by photolithography to expose one side of the through hole, and the photoresist is stripped off by sputtering, deposition or evaporation to form the connecting electrode layer on one side of the through hole. 10. The method according to claim 6, wherein the forming a plurality of two-dimensional material units on the surface of the connecting electrode layer and the insulating array layer comprises: transferring a large sheet of two-dimensional material to the upper surface of the connecting electrode layer and the insulating array layer by dry method or wet method; patterning by photolithography, protecting the two-dimensional material connected to the connection electrode layer on the through hole or on the side of the through hole, and then etching to remove the unprotected two-dimensional material, A two-dimensional material layer is formed.