Fingerprint recognition module and preparation method thereof, display panel, and display device

Abstract

The embodiments of the present application provide a fingerprint recognition module and a preparation method thereof, a display panel, and a display device. The fingerprint recognition module includes: a substrate, and a driver device layer, a first conductive structure, a piezoelectric structure, and a second conductive structure sequentially stacked on one side of the substrate; the first conductive structure is electrically connected to the driver device layer; the piezoelectric structure includes at least one focusing unit, and the focusing unit includes a first part and a second part at a first angle, so that at least part of the ultrasonic wave emitted by the first part and at least part of the ultrasonic wave emitted by the second part are focused on a designed position on a side of the substrate away from the driver device structure. The embodiments of the present application realize that each focusing unit in the piezoelectric structure can be equivalent to an acoustic lens, and the ultrasonic wave emitted by the piezoelectric structure is focused by the acoustic lens, that is, a physical method is used to make the difference in acoustic impedance of fingerprint valleys and ridges more obvious, thereby effectively improving the sensitivity or accuracy of ultrasonic fingerprint recognition products.

Description

Technical Field

[0001] The present application relates to the field of display technology. Specifically, the present application relates to a fingerprint recognition module and a preparation method thereof, a display panel, and a display device. Background Art

[0002] Fingerprint recognition, as a technology for identifying human biometrics, has been increasingly applied to more display products in recent years, providing more convenience for the realization of human-computer interaction (user and display product) functions, while also protecting user privacy to a greater extent.

[0003] Among the existing fingerprint recognition technologies, ultrasonic fingerprint recognition, as a non-destructive detection method, has unique advantages over sensors based on optical, electromagnetic wave and other technologies in some specific situations, such as when there are oil stains or stains on the user's fingers.

[0004] However, existing ultrasonic fingerprint recognition products have the disadvantages of low sensitivity or accuracy. Summary of the invention

[0005] In view of the shortcomings of the existing methods, the present application proposes a fingerprint recognition module and a preparation method thereof, a display panel, and a display device to solve the technical problem of low sensitivity or accuracy of ultrasonic fingerprint recognition products in the prior art.

[0006] In a first aspect, an embodiment of the present application provides a fingerprint recognition module, comprising: a substrate, and a driving device layer, a first conductive structure, a piezoelectric structure, and a second conductive structure sequentially stacked on one side of the substrate;

[0007] The first conductive structure is electrically connected to the driving device layer;

[0008] The piezoelectric structure includes at least one focusing unit, which includes a first part and a second part at a first angle, so that at least part of the ultrasonic wave emitted by the first part and at least part of the ultrasonic wave emitted by the second part are focused on a designed position on a side of the substrate away from the driving device structure.

[0009] In a second aspect, an embodiment of the present application provides a display panel, comprising: a display module and a fingerprint recognition module as provided in the first aspect;

[0010] One side of the display module is in contact with a side of the substrate of the fingerprint identification module that is away from the driving device structure.

[0011] In a third aspect, an embodiment of the present application provides a display device, comprising: a fingerprint recognition module as provided in the first aspect;

[0012] Or, a display panel as provided in the second aspect.

[0013] In a fourth aspect, an embodiment of the present application provides a method for preparing a fingerprint recognition module, comprising:

[0014] On one side of the substrate, a driving device layer including at least one driving device structure is prepared;

[0015] On a side of the driving device layer away from the substrate, a supporting layer including at least one protruding supporting structure is prepared, so that the supporting structure corresponds to the driving device structure; the supporting structure includes a first sub-surface and a second sub-surface at a first angle;

[0016] Preparing a first conductive structure on a side of the support layer away from the substrate, so that the first conductive structure is electrically connected to the driving device structure;

[0017] A piezoelectric structure including at least one focusing unit is prepared on a side of the support layer and the first conductive structure away from the substrate, wherein the focusing unit corresponds to the support structure one by one, and the focusing unit includes a first portion and a second portion at a first angle, so that at least a portion of the ultrasonic wave emitted by the first portion and at least a portion of the ultrasonic wave emitted by the second portion are focused on a designed position on a side of the substrate away from the driving device structure;

[0018] A second conductive structure is prepared on a side of the piezoelectric structure away from the substrate.

[0019] The beneficial technical effects brought about by the technical solution provided in the embodiments of the present application include: the first part and the second part of the focusing unit in the piezoelectric structure form a first angle, so that at least part of the ultrasonic wave emitted by the first part and at least part of the ultrasonic wave emitted by the second part can be focused, that is, each focusing unit in the piezoelectric structure can be equivalent to an acoustic lens, and the ultrasonic wave emitted by the piezoelectric structure can be focused by the acoustic lens. When the ultrasonic wave transmission power is constant, the intensity of the ultrasonic wave at the focus can be increased, thereby increasing the measured fingerprint valley and ridge acoustic impedance difference, that is, a physical method is used to make the fingerprint valley and ridge acoustic impedance difference more obvious, thereby effectively improving the sensitivity or accuracy of the ultrasonic fingerprint recognition product.

[0020] Compared with plane waves, ultrasonic focusing can better concentrate the sound pressure amplitude in the detection area, improve the sound field aliasing in the space, and increase the accuracy of fingerprint recognition.

[0021] In addition, multiple focusing units cooperate with each other to produce multi-focal focus, thereby realizing array detection of fingerprint recognition.

[0022] Additional aspects and advantages of the present application will be partially given in the following description, which will become apparent from the following description, or will be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0024] Figure 1 A schematic diagram of the structure of a fingerprint recognition module provided in an embodiment of the present application;

[0025] Figure 2 A schematic diagram of the ultrasonic focusing principle of a piezoelectric structure in a fingerprint recognition module provided in an embodiment of the present application, after omitting the first conductive structure and the second conductive structure;

[0026] Figure 3 A schematic structural diagram of a substrate, a driving device layer and a first conductive structure of a fingerprint recognition module provided in an embodiment of the present application;

[0027] Figure 4 A schematic diagram of the ultrasonic focusing principle of a fingerprint recognition module provided in an embodiment of the present application;

[0028] Figure 5 Schematic diagram of the radiation state of ultrasound;

[0029] Figure 6 A schematic diagram of a process for preparing a fingerprint recognition module provided in an embodiment of the present application;

[0030] Figure 7 A schematic flow chart of a method for preparing a fingerprint recognition module provided in an embodiment of the present application.

[0031] Figure 8 A schematic diagram of a film structure after preparing a driving device layer including at least one driving device structure on one side of a substrate in a method for preparing a fingerprint recognition module according to an embodiment of the present application;

[0032] Fig. 9 In the method for preparing a fingerprint recognition module provided in the embodiment of the present application, a support layer including at least one protruding support structure is prepared on the side of the driving device layer away from the substrate, so that the support structure corresponds to the driving device structure. A schematic diagram of the film layer structure after the support structure includes a first sub-surface and a second sub-surface at a first angle;

[0033] Fig.10 A schematic diagram of a film structure after a first conductive layer is deposited on a support structure, an inner wall of a through hole, and a portion of an exposed driving device structure in a method for preparing a fingerprint recognition module provided in an embodiment of the present application;

[0034] Fig.11In a method for preparing a fingerprint recognition module provided in an embodiment of the present application, a piezoelectric structure including at least one focusing unit is prepared on a side of a support layer and a first conductive structure away from a substrate, the focusing unit corresponds to the support structure one by one, and the focusing unit includes a first portion and a second portion at a first angle, so that at least part of the ultrasonic wave emitted by the first portion and at least part of the ultrasonic wave emitted by the second portion are focused on a designed position on a side of the substrate away from a driving device structure;

[0035] In the figure:

[0036] 10-substrate; 11-display area;

[0037] 20-driving device layer; 21-driving device structure;

[0038] 30-support layer; 31-support structure; 31a-first sub-surface; 31b-second sub-surface; 32-via;

[0039] 40-first conductive structure; 41-conductive unit;

[0040] 50-piezoelectric structure; 51-focusing unit; 51a-first part; 51b-second part;

[0041] 60- a second conductive structure;

[0042] A-focusing direction; B-tandem direction;

[0043] 1-ultrasonic main lobe; 2-ultrasonic side lobe; 3-null value. DETAILED DESCRIPTION

[0044] The present application is described in detail below, and examples of embodiments of the present application are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar components or components with the same or similar functions. In addition, if the detailed description of the known technology is unnecessary for the features of the present application shown, it will be omitted. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application.

[0045] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as here.

[0046] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0047] First, several terms involved in this application are introduced and explained:

[0048] Ultrasonic wave: The frequency range of sound audible to human ear is 20Hz (Hertz) - 20KHz (kilohertz). Waves with frequency lower than 20Hz are called infrasound waves, and waves with frequency higher than 20KHz are called ultrasonic waves. The frequency is the number of vibrations completed within 1s (second).

[0049] Piezoelectric material: a functional material that can realize the mutual conversion between mechanical signals and electrical signals, mainly including quartz crystal, piezoelectric ceramics, organic PVDF (polyvinylidene fluoride) piezoelectric film and aluminum nitride, etc., with positive piezoelectric effect and inverse piezoelectric effect. When a certain force is applied to the piezoelectric material, positive and negative charges proportional to the magnitude of the applied force will appear on the surface of the material. This phenomenon is the positive piezoelectric effect of the material; when a certain voltage is applied to the piezoelectric material, the piezoelectric material will deform and vibrate, etc. This phenomenon is the inverse piezoelectric effect of the piezoelectric material.

[0050] The inventor of this application has conducted research and found that the ultrasonic fingerprint recognition technology can utilize the principle of the difference in acoustic impedance of fingerprint valleys and ridges. Specifically, when the ultrasonic wave excited by the ultrasonic wave transmitting component reaches the fingerprint surface through the propagation medium, since the fingerprint valley is in air, the acoustic impedance at this interface is seriously mismatched, causing almost 100% reflection of the ultrasonic wave energy, while the acoustic impedance matching at the fingerprint ridge position is better, and only a small amount of ultrasonic wave energy is reflected; the reflected ultrasonic wave is then received by the ultrasonic wave receiving component through the propagation medium and converted into an electrical signal, and the electrical signal can be processed to obtain an image of the fingerprint valley and ridge distribution.

[0051] In existing ultrasonic fingerprint recognition products, the emission angles of the emitted ultrasonic waves are basically in the same direction or parallel. When the ultrasonic emission power is constant, there is a phenomenon that the measured acoustic impedance differences of the fingerprint valleys and ridges are not obvious, which will lead to technical problems such as low sensitivity or accuracy of ultrasonic fingerprint recognition products.

[0052] The fingerprint recognition module and its preparation method, display panel, and display device provided in the present application are intended to solve the above technical problems of the prior art.

[0053] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments.

[0054] The present application embodiment provides a fingerprint recognition module, the structure diagram of which is as follows: Figure 1 and Figure 2 As shown, it includes: a substrate 10, and a driving device layer 20, a first conductive structure 40, a piezoelectric structure 50 and a second conductive structure 60 which are sequentially stacked on one side of the substrate 10.

[0055] The first conductive structure 40 is electrically connected to the driving device layer 20 .

[0056] The piezoelectric structure 50 includes at least one focusing unit 51, which includes a first part 51a and a second part 51b at a first angle, so that at least part of the ultrasonic wave emitted by the first part 51a and at least part of the ultrasonic wave emitted by the second part 51b are focused on a designed position on a side of the substrate 10 away from the driving device structure 21.

[0057] In this embodiment, the first part 51a and the second part 51b of the focusing unit 51 in the piezoelectric structure 50 form a first angle, so that at least part of the ultrasonic wave emitted by the first part 51a and at least part of the ultrasonic wave emitted by the second part 51b can be focused, that is, each focusing unit 51 in the piezoelectric structure 50 can be equivalent to an acoustic lens.

[0058] The focusing principle of optical lenses on light is well known, and the focusing of acoustic lenses on sound waves is also based on the same principle. According to Snell's law, sound waves will be refracted when passing through the interface between different media. Therefore, the incident wave can be focused to one point, namely the focus, after passing through a lens with appropriate curvature. The propagation of sound waves in the medium usually uses the theory of ray acoustics and wave acoustics. In the case of high frequencies, the propagation of sound waves in the medium can be regarded as the propagation of sound lines in the medium. Snell's law is a classic theory in ray acoustics. Sound waves will be refracted when encountering the interface between media. The refraction angle is related to the density of the medium, as shown in the formula Among them, θ1 is the incident angle, θ2 is the exit angle, C1 is the speed of sound in the lens material, and C2 is the speed of sound in the medium, that is, if the sound wave is incident perpendicular to the interface, it will still exit perpendicularly.

[0059] In this embodiment, the ultrasonic waves emitted by the piezoelectric structure 50 are focused by an acoustic lens formed by the focusing unit 51. The intensity of the ultrasonic waves at the focus can be increased when the ultrasonic transmission power is constant, thereby increasing the measured acoustic impedance difference between the fingerprint valleys and ridges. That is, a physical method is used to make the acoustic impedance difference between the fingerprint valleys and ridges more obvious, thereby effectively improving the sensitivity or accuracy of the ultrasonic fingerprint recognition product.

[0060] Compared with plane waves, ultrasonic focusing can better concentrate the sound pressure amplitude in the detection area, improve the sound field aliasing in the space, and increase the accuracy of fingerprint recognition.

[0061] Optionally, the first part 51a and the second part 51b of the focusing unit 51 are respectively regarded as an ultrasonic emitting array element, and the ultrasonic waves emitted by all the array elements are line sources of the same frequency and the same phase, the direction of the sound line is perpendicular to the array element direction, and there is a first angle between adjacent array elements, so the ultrasonic waves emitted by each array element can form multiple focal points, and the focal points can be focused on the finger valley or ridge on the side of the substrate 10 away from the driving device layer 20. That is, the multiple focusing units 51 cooperate with each other to produce multi-focal focus, thereby realizing array detection of fingerprint recognition.

[0062] Optionally, the side of the substrate 10 away from the driving device layer 20 may be close to the cover plate, and the substrate 10 may also include the cover plate or be the cover plate itself.

[0063] Optionally, the designed position can match the detection position of the finger during fingerprint recognition.

[0064] Optionally, the second conductive structure 60 can be used for a driving channel (Tx), that is, after receiving an electrical signal, the second conductive structure 60 excites the piezoelectric structure 50 to deform and emit ultrasonic waves. The first conductive structure 40 can be used for a sensing channel (Rx), that is, the reflected ultrasonic waves excite the piezoelectric material again to convert the mechanical signal into an electrical signal in the first conductive structure 40, which is then sensed by the driving device layer 20 (such as a TFT array) and imaged to achieve fingerprint recognition.

[0065] Optionally, the second conductive structure 60 is made of silver.

[0066] In some possible implementations, the intersection line between the surfaces of the first portion 51a and the second portion 51b close to the first conductive structure 40 and the first plane is a wavy line or a sawtooth line, and the first plane is perpendicular to the substrate 10, the first portion 51a and the second portion 51b.

[0067] In this embodiment, the focusing unit 51 of the piezoelectric structure 50 may form a wavy or sawtooth-shaped piezoelectric structure 50 to form an ultrasonic emission array with different incident directions, thereby generating multi-focal focus.

[0068] It should be noted that the wavy or sawtooth focusing unit 51 is a finite length array element, and the focus position of fingerprint recognition is at the near field position of the sound source. Therefore, the ultrasonic wave emitted by the focusing unit 51 cannot be regarded as a plane wave, but should be regarded as a cylindrical wave, such as Figure 5 As shown, cylindrical waves have high directivity, which is conducive to focusing, thereby improving the sensitivity or accuracy of ultrasonic fingerprint recognition products.

[0069] In some possible implementations, such as Figure 2 As shown, the intersection of the perpendicular midline of the first part 51a and the perpendicular midline of the second part 51b is located at the designed position. In this way, on the one hand, it is conducive to selecting the ultrasonic wave emitted perpendicular to the first part 51a and the second part 51b in the focusing unit 51 for fingerprint recognition; on the other hand, the energy of this part of ultrasonic wave is relatively large, which is conducive to improving the sensitivity or accuracy of ultrasonic fingerprint recognition products; on the other hand, it is conducive to controlling the emission direction of ultrasonic wave, making the focusing more accurate.

[0070] In some possible implementations, such as Figure 2 As shown, the sum of the second angle between the direction of the main lobe of the ultrasonic wave and the direction perpendicular to the substrate 10 and half of the first angle is 90°; the second angle corresponds to the inverse sine function of the ratio of the wavelength of the ultrasonic wave to the length of the line sound source, and the length of the line sound source is the length of the first part 51a or the second part 51b.

[0071] Optionally, the first angle satisfies the following formula: Wherein θ is the first angle, λ is the wavelength of the ultrasonic wave, and a is the length of the first portion 51a or the second portion 51b (ie, the length of the line sound source).

[0072] In this embodiment, let λ be the wavelength of the ultrasonic wave, a be the length of the line source, α be the angle between the line from the focus to the end of the line source and the direction of the sound line (i.e., the second angle), and θ be the angle between two adjacent line sources (i.e., the first angle).

[0073] The relationship between α and a satisfies formula 1:

[0074] In order to select the part of ultrasonic wave with larger energy for fingerprint recognition, that is, the direction of the sound line is perpendicular to the line source, therefore, the relationship between α and θ satisfies formula 2:

[0075] From equation 1 and equation 2, we can get equation 3:

[0076] If the glass thickness is 500 μm (micrometers) and the emission frequency is 10 MHz (megahertz), it can be theoretically calculated that the line source size a≈1340 μm, α≈33 degrees, and θ≈114 degrees, so the distance between two adjacent foci is approximately d=2248 μm.

[0077] If the frequency is fixed, the distance between two adjacent focal points is fixed to d. It can be understood that the distance between two adjacent focal points corresponds to the imaging resolution during fingerprint recognition, that is, the detection accuracy of fingerprint recognition. The focal position can be changed by changing the frequency of the transmitted wave and the direction of the sound line (i.e., directivity), thereby adjusting the distance between two adjacent focal points and the detection accuracy of fingerprint recognition; the distance between two adjacent focal points can also be set by setting the first angle between the first part 51a and the second part 51b of the focusing unit 51, thereby setting the detection accuracy of the fingerprint recognition product.

[0078] The inventor of the present application considers that the first portion 51a and the second portion 51b of the focusing unit 51 in the piezoelectric structure 50 need to form a first angle, and the structure can be implemented based on a full film forming process in the semiconductor manufacturing process. To this end, the present application provides the following possible implementation method for the fingerprint recognition module:

[0079] like Figure 1 and Figure 2 As shown, the fingerprint recognition module of the embodiment of the present application further includes: a supporting layer 30 .

[0080] The support layer 30 is located between the driving device layer 20 and the first conductive structure 40 .

[0081] The support layer 30 includes at least one support structure 31 protruding from the driving device layer 20 toward the first conductive structure 40 , and the support structure 31 corresponds to the focusing unit 51 one by one.

[0082] In this embodiment, the support layer 30 can provide support for the first part 51a and the second part 51b of the focusing unit 51 in the piezoelectric structure 50, so as to help the first part 51a and the second part 51b of the focusing unit 51 to be at a first angle. Specifically, each support structure 31 in the support layer 30 that protrudes from the driving device layer 20 toward the first conductive structure 40 provides support for a focusing unit 51 in the piezoelectric structure 50. In addition, in the semiconductor manufacturing process, it is easier to etch and shape the surface of the side of the support layer 30 away from the substrate 10, so that the piezoelectric structure 50 can form a focusing unit 51 with the first part 51a and the second part 51b at a first angle through a full film forming process.

[0083] Optionally, a side surface of each supporting structure 31 in the supporting layer 30 away from the substrate 10 may include a first sub-surface 31a and a second sub-surface 31b at a first angle, and the first sub-surface 31a and the second sub-surface 31b correspond to the first part 51a and the second part 51b of the focusing unit 51 in the piezoelectric structure 50, respectively.

[0084] In some possible implementations, the support structure 31 has a via 32 , one end of the via 32 is electrically connected to the first conductive structure 40 , and the other end of the via 32 is electrically connected to the driving device structure 21 .

[0085] In some possible implementations, the acoustic impedance of the support structure 31 is not greater than the acoustic impedance of the substrate 10, and the acoustic impedance of the support structure 31 is not less than the acoustic impedance of the piezoelectric structure 50. That is, the order of the acoustic impedance from large to small is: substrate 10 ≥ support structure 31 ≥ piezoelectric structure 50. This is conducive to the propagation of ultrasonic waves.

[0086] Optionally, the substrate 10 is made of glass material, the piezoelectric structure 50 is made of PVDF (polyvinylidene fluoride) material, and the support structure 31 is made of PET (Polyethylene terephthalate, polyester resin) material.

[0087] In some possible implementations, the focusing units 51 are arranged in an array.

[0088] In this embodiment, the focusing units 51 in the piezoelectric structure 50 are arranged in an array to obtain a focus array, thereby realizing array detection of fingerprint recognition.

[0089] In some possible implementations, such as Figure 3 As shown, the driving device layer 20 includes at least one driving device structure 21 , and the driving device structure 21 corresponds to the focusing unit 51 .

[0090] In this embodiment, the driving device structure 21 in the driving device layer 20 corresponds to the focusing unit 51 , which can facilitate controlling the operation of each focusing unit 51 .

[0091] Optionally, the driving device structure 21 corresponds to the focusing unit 51 one by one, so that each focusing unit 51 can be independently controlled, thereby effectively improving the accuracy of fingerprint recognition.

[0092] In some possible implementations, such as Figure 3 and Figure 4 As shown, the first conductive structure 40 includes at least one conductive unit 41 corresponding to the focusing unit 51. The first conductive units 41 located in the same row or column are connected in series, and the series connection direction is perpendicular to the first direction. The first direction is the projection direction of the line between the focusing unit 51 and the design position on the plane where the substrate 10 is located.

[0093] In this embodiment, the series connection direction of the conductive units 41 is perpendicular to the direction of the sound line, and the series connection direction of the conductive units 41 is perpendicular to the direction of ultrasonic focusing detection, that is, the series connection direction of the conductive units 41 is perpendicular to the direction of the sound line, which is beneficial to reduce the possible impact of the current in the first conductive structure 40 on the ultrasonic focusing, thereby ensuring the accuracy of fingerprint recognition.

[0094] Optionally, the conductive units 41 correspond to the focusing units 51 one by one.

[0095] Based on the same inventive concept, an embodiment of the present application provides a display panel, comprising: a display module and any fingerprint recognition module provided in the aforementioned embodiments.

[0096] One side of the display module is in contact with a side of the substrate 10 of the fingerprint identification module away from the driving device structure 21 .

[0097] In this embodiment, since the display panel adopts any one of the fingerprint recognition modules provided in the aforementioned embodiments, its principles and technical effects can be referred to in the aforementioned embodiments and will not be described in detail here.

[0098] In some possible implementations, the display panel includes an anode layer, a light-emitting layer, and a cathode layer that are stacked in sequence.

[0099] In this embodiment, the display panel adopts a display structure such as LED (light emitting diode) or Micro-LED (micro light emitting diode) or OLED (Organic Light-Emitting Diode).

[0100] Based on the same inventive concept, an embodiment of the present application provides a display device, comprising: any fingerprint recognition module provided in the above embodiments. Or, any display panel provided in the above embodiments.

[0101] In this embodiment, the display device may be at least one of any products or components having fingerprint recognition and display functions, such as a television, a digital photo frame, a mobile phone, a smart watch, and a tablet computer.

[0102] Since the display device adopts any one of the fingerprint recognition modules provided in the aforementioned embodiments, or any one of the display panels provided in the aforementioned embodiments, its principles and technical effects can be referred to in the aforementioned embodiments, which will not be described in detail here.

[0103] Based on the same inventive concept, the present application embodiment provides a method for preparing a fingerprint recognition module, and the flow chart of the method is as follows: Figure 6 As shown, the method includes steps S101-S105:

[0104] S101: On one side of a substrate, a driving device layer including at least one driving device structure is prepared.

[0105] S102: On a side of the driving device layer away from the substrate, a supporting layer including at least one protruding supporting structure is prepared, so that the supporting structure corresponds to the driving device structure. The supporting structure includes a first sub-surface and a second sub-surface at a first angle.

[0106] S103: preparing a first conductive structure on a side of the support layer away from the substrate, so that the first conductive structure 40 is electrically connected to the driving device structure.

[0107] S104: On a side of the support layer and the first conductive structure away from the substrate, prepare a piezoelectric structure including at least one focusing unit, wherein the focusing unit corresponds to the support structure one-to-one, and the focusing unit includes a first part and a second part at a first angle, so that at least part of the ultrasonic wave emitted by the first part and at least part of the ultrasonic wave emitted by the second part are focused on a designed position on a side of the substrate away from the driving device structure.

[0108] S105: preparing a second conductive structure on a side of the piezoelectric structure away from the substrate.

[0109] In this embodiment, the structure in which the first part 51a and the second part 51b of the focusing unit 51 in the piezoelectric structure 50 present a first angle can be prepared based on the full film forming process. Specifically, by introducing the support layer 30 and etching and shaping the surface of the side of the support layer 30 away from the substrate 10, the first sub-surface 31a and the second sub-surface 31b presenting the first angle are obtained, so that the subsequent film layers including but not limited to the first conductive structure 40 and the piezoelectric structure 50 can still form a structure presenting the first angle corresponding to the first sub-surface 31a and the second sub-surface 31b of the support structure 31 based on the full film forming process. As for the piezoelectric structure 50, the focusing unit 51 including the first part 51a and the second part 51b presenting the first angle can be prepared based on the full film forming process.

[0110] In the fingerprint recognition module prepared in this way, each focusing unit 51 in the piezoelectric structure 50 can be equivalent to an acoustic lens, which can focus at least part of the ultrasonic wave emitted by the first part 51a and at least part of the ultrasonic wave emitted by the second part 51b in the focusing unit 51, and can increase the intensity of the ultrasonic wave at the focus when the ultrasonic wave transmission power is constant, thereby increasing the measured difference in acoustic impedance of the fingerprint valley and ridge, that is, using a physical method to make the difference in acoustic impedance of the fingerprint valley and ridge more obvious, thereby effectively improving the sensitivity or accuracy of the ultrasonic fingerprint recognition product.

[0111] The present application embodiment provides a method for preparing a fingerprint recognition module. The flowchart of the method is as follows: Figure 7As shown, the following steps S201-S207 are included:

[0112] S201: On one side of the substrate, a driving device layer including at least one driving device structure is prepared.

[0113] The film structure obtained through this step is as follows Figure 8 shown.

[0114] In this step, a driving device layer 20 is manufactured on one side surface of the substrate 10, and at least part of the driving device structure 21 in the driving device layer 20 can correspond to the focusing unit 51 in the piezoelectric structure 50 prepared subsequently, and the distance between two adjacent driving device structures 21 can correspond to the imaging resolution during fingerprint recognition.

[0115] Optionally, the substrate 10 may be made of glass.

[0116] Optionally, the distance between two adjacent driving device structures 21 may be about 2248 μm.

[0117] S202: On a side of the driving device layer away from the substrate, prepare a supporting layer including at least one protruding supporting structure, such that the supporting structure corresponds to the driving device structure. The supporting structure includes a first sub-surface and a second sub-surface at a first angle.

[0118] The film structure obtained through this step is as follows Fig. 9 shown.

[0119] In this step, a support layer 30 can be manufactured on the driving device layer 20 based on a full film forming process, and then at least one protruding support structure 31 is formed on the surface of the support layer 30 by controlling etching or exposure. The first sub-surface 31a and the second sub-surface 31b of the support structure 31 which are at a first angle are adapted to the angle of the focusing unit 51 in the subsequently prepared piezoelectric structure 50.

[0120] It should be noted that, under the condition of constant photolithography intensity, if the target etching width is less than half of the target etching depth, the etched sidewall is similar to the sidewall of the cone, that is, the etched sidewall is a slope (the etched sidewall is easy to form an angle with the etching direction), and the actual etching depth is often less than the target etching depth; if the target etching width is greater than half of the target etching depth, the etched sidewall is similar to the sidewall of the hexahedron, that is, the etched sidewall is basically parallel to the etching direction, and the actual etching depth can basically reach the target etching depth. Therefore, the shape or length of the etched film layer can be controlled by controlling etching or exposure, that is, the first sub-surface 31a and the second sub-surface 31b with a first angle can be obtained on one side of the support structure 31.

[0121] Optionally, the thickness of the support layer 30 may be about 730 μm.

[0122] Optionally, the support layer 30 may be made of a material having an acoustic impedance between that of the piezoelectric structure 50 and the glass substrate 10 , such as PET (Polyethylene terephthalate, polyester resin) material.

[0123] S203: etching the support structure so that the support structure has a through hole exposing a portion of the driving device structure.

[0124] After this step, the through hole etched on the support structure 31 can facilitate the first conductive structure 40 to be prepared subsequently to be electrically connected to the driving device structure 21 .

[0125] S204: depositing a first conductive layer on the support structure, the inner wall of the through hole, and the exposed portion of the driving device structure.

[0126] The film structure obtained through this step is as follows Fig.10 shown.

[0127] After this step, a first conductive layer is prepared on the support structure 31 , and the through hole on the support structure 31 becomes a via 32 that can electrically connect the first conductive layer and the driving device structure 21 .

[0128] S205: patterning the first conductive layer to obtain a first conductive structure.

[0129] In this step, the first conductive layer may be patterned by using a patterned photoresist in combination with etching to form a first conductive structure 40 including a plurality of first conductive units 41 .

[0130] S206: On a side of the support layer and the first conductive structure away from the substrate, prepare a piezoelectric structure including at least one focusing unit, wherein the focusing unit corresponds to the support structure one-to-one, and the focusing unit includes a first part and a second part at a first angle, so that at least part of the ultrasonic wave emitted by the first part and at least part of the ultrasonic wave emitted by the second part are focused on a designed position on a side of the substrate away from the driving device structure.

[0131] The film structure obtained through this step is as follows Fig.11 shown.

[0132] In this step, the preparation of the piezoelectric structure 50 can utilize the surface morphology of the formed support structure 31, and based on the full film forming process, a focusing unit 51 including a first portion 51a and a second portion 51b with a first angle can be formed.

[0133] Optionally, the sum of the second angle between the direction of the main lobe of the ultrasonic wave and the direction perpendicular to the substrate 10 and half of the first angle is 90°; the second angle corresponds to the inverse sine function of the ratio of the wavelength of the ultrasonic wave to the length of the line sound source, and the length of the line sound source is the length of the first part 51a or the second part 51b.

[0134] Optionally, the first angle satisfies the following formula: Wherein θ is the first angle, λ is the wavelength of the incident sound wave, and a is the length of the first portion 51 a or the second portion 51 b.

[0135] S207: preparing a second conductive structure on a side of the piezoelectric structure away from the substrate.

[0136] The film structure obtained through this step is as follows Figure 1 shown.

[0137] After this step, a sandwich-shaped ultrasonic transceiver structure including the first conductive structure 40 , the piezoelectric structure 50 and the second conductive structure 60 is formed in the fingerprint recognition module to realize fingerprint recognition based on ultrasonic detection.

[0138] It should be noted that after step S207 , a film layer planarization process may be performed to facilitate the preparation of subsequent film layers.

[0139] Optionally, a flat layer is prepared on a side of the second conductive structure 60 away from the piezoelectric structure 50 .

[0140] Optionally, the surface of one side of the second conductive structure 60 away from the piezoelectric structure 50 is directly planarized.

[0141] By applying the embodiments of the present application, at least the following beneficial effects can be achieved:

[0142] 1. The first part 51a and the second part 51b of the focusing unit 51 in the piezoelectric structure 50 form a first angle, so that at least part of the ultrasonic wave emitted by the first part 51a and at least part of the ultrasonic wave emitted by the second part 51b can be focused, that is, each focusing unit 51 in the piezoelectric structure 50 can be equivalent to an acoustic lens.

[0143] 2. By focusing the ultrasonic waves emitted by the piezoelectric structure 50 through the acoustic lens formed by the focusing unit 51, the intensity of the ultrasonic waves at the focus can be increased under the condition of a certain ultrasonic emission power, thereby increasing the measured difference in acoustic impedance of the fingerprint valleys and ridges. That is, a physical method is used to make the difference in acoustic impedance of the fingerprint valleys and ridges more obvious, thereby effectively improving the sensitivity or accuracy of ultrasonic fingerprint recognition products.

[0144] 3. Ultrasonic focusing can better concentrate the sound pressure amplitude in the detection area, improve the sound field aliasing in the space, and increase the accuracy of fingerprint recognition.

[0145] 4. Multiple focusing units 51 cooperate with each other to produce multi-focal focus, thereby realizing array detection of fingerprint recognition.

[0146] 5. The focusing unit 51 of the piezoelectric structure 50 can form a wavy or sawtooth piezoelectric structure 50 to form an ultrasonic emission array with different incident directions, thereby generating multi-focus focusing. The focusing units 51 in the piezoelectric structure 50 are arranged in an array to obtain a focus array, thereby realizing array detection of fingerprint recognition.

[0147] 6. The intersection of the perpendicular midline of the first part 51a and the perpendicular midline of the second part 51b is located at the designed position. In this way, on the one hand, it is conducive to selecting the ultrasonic wave emitted perpendicular to the first part 51a and the second part 51b in the focusing unit 51 for fingerprint recognition; on the other hand, the energy of this part of ultrasonic wave is relatively large, which is conducive to improving the sensitivity or accuracy of ultrasonic fingerprint recognition products; on the other hand, it is conducive to controlling the emission direction of ultrasonic wave, making the focusing more accurate.

[0148] 7. The support layer 30 can provide support for the first part 51a and the second part 51b of the focusing unit 51 in the piezoelectric structure 50, so as to help the first part 51a and the second part 51b of the focusing unit 51 to be at a first angle. Specifically, each support structure 31 in the support layer 30 that protrudes from the driving device layer 20 toward the first conductive structure 40 provides support for a focusing unit 51 in the piezoelectric structure 50. In addition, in the semiconductor manufacturing process, it is easier to etch and shape the surface of the side of the support layer 30 away from the substrate 10, so that the piezoelectric structure 50 can form a focusing unit 51 with the first part 51a and the second part 51b at a first angle through a comprehensive film forming process.

[0149] 8. The acoustic impedance of the support structure 31 is not greater than the acoustic impedance of the substrate 10, and the acoustic impedance of the support structure 31 is not less than the acoustic impedance of the piezoelectric structure 50. This is beneficial to the propagation of ultrasonic waves.

[0150] 9. The driving device structure 21 in the driving device layer 20 corresponds to the focusing unit 51 , which can facilitate the control of the operation of each focusing unit 51 .

[0151] 10. The series connection direction of the conductive unit 41 is perpendicular to the direction of the sound line. The series connection direction of the conductive unit 41 is perpendicular to the direction of the ultrasonic focusing detection, that is, the series connection direction of the conductive unit 41 is perpendicular to the direction of the sound line. This is beneficial to reduce the possible impact of the current in the first conductive structure 40 on the ultrasonic focusing, thereby ensuring the accuracy of fingerprint recognition.

[0152] Those skilled in the art will appreciate that the various operations, methods, steps, measures, and schemes in the processes discussed in this application may be alternated, altered, combined, or deleted. Further, other steps, measures, and schemes in the various operations, methods, and processes discussed in this application may also be alternated, altered, rearranged, decomposed, combined, or deleted. Further, the steps, measures, and schemes in the prior art that are similar to those disclosed in this application may also be alternated, altered, rearranged, decomposed, combined, or deleted.

[0153] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0154] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0155] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0156] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0157] It should be understood that, although the steps in the flowchart of the accompanying drawings are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

[0158] The above is only a partial implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A fingerprint recognition module, characterized in that: include: A substrate, and a driving device layer, a first conductive structure, a piezoelectric structure, and a second conductive structure sequentially stacked on one side of the substrate; The first conductive structure is electrically connected to the driving device layer; The piezoelectric structure includes at least one focusing unit, which includes a first part and a second part at a first angle, so that at least part of the ultrasonic wave emitted by the first part and at least part of the ultrasonic wave emitted by the second part are focused on a designed position on a side of the substrate away from the driving device structure.

2. The fingerprint recognition module according to claim 1, characterized in that: The intersection lines of the surfaces of the first portion and the second portion close to the first conductive structure and the first plane are wavy lines or sawtooth lines, and the first plane is perpendicular to the substrate, the first portion and the second portion.

3. The fingerprint recognition module according to claim 1 or 2, characterized in that: An intersection point of a perpendicular bisector of the first portion and a perpendicular bisector of the second portion is located at the designed position.

4. The fingerprint recognition module according to claim 3, characterized in that: The sum of a second angle between the direction of the main lobe of the ultrasonic wave and the direction perpendicular to the substrate and half of the first angle is 90°; the second angle corresponds to the inverse sine function of the ratio of the wavelength of the ultrasonic wave to the length of the line sound source, and the length of the line sound source is the length of the first part or the second part.

5. The fingerprint recognition module according to claim 1, characterized in that: The fingerprint recognition module further includes: a support layer; The support layer is located between the driving device layer and the first conductive structure; The support layer includes at least one support structure protruding from the driving device layer toward the first conductive structure, and the support structure corresponds to the focusing unit one by one.

6. The fingerprint recognition module according to claim 5, characterized in that: The acoustic impedance of the support structure is not greater than the acoustic impedance of the substrate, and the acoustic impedance of the support structure is not less than the acoustic impedance of the piezoelectric structure.

7. The fingerprint recognition module according to claim 1, characterized in that: The focusing units are arranged in an array; The driving device layer includes at least one driving device structure, and the driving device structure corresponds to the focusing unit; The first conductive structure includes at least one conductive unit corresponding to the focusing unit. The first conductive units located in the same row or column are connected in series, and the series direction is perpendicular to the first direction. The first direction is the projection direction of the line between the focusing unit and the design position on the plane where the substrate is located.

8. A display panel, characterized in that: include: A display module and a fingerprint recognition module as claimed in any one of claims 1 to 7; One side of the display module is in contact with a side of the substrate of the fingerprint identification module away from the driving device structure.

9. A display device, characterized in that: include: The fingerprint recognition module according to any one of claims 1 to 7; Or, the display panel as claimed in claim 8.

10. A method for preparing a fingerprint recognition module, characterized in that: include: On one side of the substrate, a driving device layer including at least one driving device structure is prepared; On a side of the driving device layer away from the substrate, a supporting layer including at least one protruding supporting structure is prepared, so that the supporting structure corresponds to the driving device structure; the supporting structure includes a first sub-surface and a second sub-surface at a first angle; Preparing a first conductive structure on a side of the support layer away from the substrate, so that the first conductive structure is electrically connected to the driving device structure; A piezoelectric structure including at least one focusing unit is prepared on a side of the support layer and the first conductive structure away from the substrate, wherein the focusing unit corresponds to the support structure one by one, and the focusing unit includes a first portion and a second portion at a first angle, so that at least a portion of the ultrasonic wave emitted by the first portion and at least a portion of the ultrasonic wave emitted by the second portion are focused on a designed position on a side of the substrate away from the driving device structure; A second conductive structure is prepared on a side of the piezoelectric structure away from the substrate.

11. The preparation method according to claim 10, characterized in that: The step of preparing a first conductive structure on a side of the support layer away from the substrate so that the first conductive structure is electrically connected to the driving device structure comprises: Etching the support structure so that the support structure has a through hole exposing a portion of the drive device structure; Depositing a first conductive layer on the support structure, the inner wall of the through hole and the exposed portion of the driving device structure; The first conductive layer is patterned to obtain the first conductive structure.

12. The preparation method according to claim 10 or 11, characterized in that: The sum of a second angle between the direction of the main lobe of the ultrasonic wave and the direction perpendicular to the substrate and half of the first angle is 90°; the second angle corresponds to the inverse sine function of the ratio of the wavelength of the ultrasonic wave to the length of the line sound source, and the length of the line sound source is the length of the first part or the second part.

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