Ultrasonic fingerprint recognition device and its preparation method, and display device

Abstract

The embodiments of the present disclosure provide an ultrasonic fingerprint recognition device and a preparation method thereof, and a display device. The ultrasonic fingerprint recognition device includes: a substrate and a receiving electrode layer, a piezoelectric material layer, and a transmitting electrode layer stacked in sequence on the substrate, wherein a side of the piezoelectric material layer close to the transmitting electrode layer is a curved surface structure, and the ultrasonic signal generated by the piezoelectric material layer can be converged along the direction of the piezoelectric material layer away from the transmitting electrode layer to enhance the strength of the ultrasonic signal.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to, but are not limited to, the field of ultrasonic fingerprint recognition technology, and in particular to an ultrasonic fingerprint recognition device and a preparation method thereof, and a display device. Background Art

[0002] Compared with fingerprint technology based on capacitive touch screens, ultrasonic fingerprint technology has many unique advantages, including the ability to scan through smartphone casings made of glass or plastic, and the scanning will not be affected by dirt such as sweat, hand cream or condensation that may exist on the fingers, thus providing a more stable and accurate fingerprint recognition method.

[0003] However, the fingerprint recognition process of ultrasonic fingerprint recognition devices in some technologies is greatly affected by the surrounding environmental noise, and the fingerprint recognition effect needs to be improved. Summary of the invention

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0005] The embodiments of the present disclosure provide an ultrasonic fingerprint recognition device and a manufacturing method thereof, and a display device, which can enhance the ultrasonic intensity and thus improve the fingerprint recognition accuracy.

[0006] The embodiments of the present disclosure mainly provide the following technical solutions:

[0007] In a first aspect, an embodiment of the present disclosure provides an ultrasonic fingerprint recognition device, comprising: a substrate and a receiving electrode layer, a piezoelectric material layer and a transmitting electrode layer stacked in sequence on the substrate, wherein a side of the piezoelectric material layer close to the transmitting electrode layer is a curved structure, and the ultrasonic signal generated by the piezoelectric material layer can be converged in a direction away from the transmitting electrode layer to enhance the strength of the ultrasonic signal.

[0008] In a second aspect, an embodiment of the present disclosure provides a display device, comprising: a display panel and the ultrasonic fingerprint recognition device described above, wherein the ultrasonic fingerprint recognition device is arranged on a non-light emitting surface of the display panel.

[0009] In a third aspect, an embodiment of the present disclosure provides a method for preparing an ultrasonic fingerprint recognition device, comprising: forming a receiving electrode layer on a substrate; forming a piezoelectric material layer on the receiving electrode layer, wherein a side of the piezoelectric material layer close to the transmitting electrode layer is a curved structure, and the ultrasonic signal generated by the piezoelectric material layer can be converged in a direction away from the transmitting electrode layer to enhance the intensity of the ultrasonic signal; and forming the transmitting electrode layer on the piezoelectric material layer.

[0010] The ultrasonic fingerprint recognition device and its preparation method and display device provided by the embodiments of the present disclosure may include: a substrate and a receiving electrode layer, a piezoelectric material layer and a transmitting electrode layer stacked in sequence on the substrate, wherein the side of the piezoelectric material layer close to the transmitting electrode layer is a curved surface structure. In this way, through the curved surface structure, the ultrasonic signal generated by the piezoelectric material layer can be converged in a direction away from the transmitting electrode layer. In this way, ultrasonic focusing is achieved by optimizing the structure of the piezoelectric material layer, so that the ultrasonic wave resonates / resonates at the intersection, which can enhance the energy and intensity of the ultrasonic signal and has a higher recognition degree when noise exists. Therefore, the ultrasonic fingerprint recognition device provided by the embodiments of the present disclosure can perform fingerprint recognition in the form of ultrasonic focusing, and can achieve improved fingerprint recognition accuracy.

[0011] Other features and advantages of the present disclosure will be described in the following description, and partly become apparent from the description, or be understood by implementing the present disclosure. Other advantages of the present disclosure can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings are used to provide an understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation on the technical solution of the present disclosure. The shapes and sizes of the components in the accompanying drawings do not reflect the actual proportions and are only intended to illustrate the content of the present disclosure.

[0013] Figure 1A It is a schematic diagram of the structure of an ultrasonic fingerprint recognition device in some technologies;

[0014] Figure 1B A schematic diagram of the fingerprint recognition process in some technologies;

[0015] Figure 2 A schematic diagram of the structure of an ultrasonic fingerprint recognition device in an embodiment of the present disclosure;

[0016] Figure 3 is a schematic diagram of a fingerprint recognition process in an embodiment of the present disclosure;

[0017] Figure 4A Another schematic diagram of the structure of the ultrasonic fingerprint recognition device in the embodiment of the present disclosure;

[0018] Figure 4B It is another structural schematic diagram of the ultrasonic fingerprint recognition device in the embodiment of the present disclosure;

[0019] Figure 4C It is another structural schematic diagram of the ultrasonic fingerprint recognition device in the embodiment of the present disclosure;

[0020] Figure 5 is a schematic diagram of simulation results of ultrasonic signals in an embodiment of the present disclosure;

[0021] Fig. 6A is a schematic diagram of the structure of a display device in an embodiment of the present disclosure;

[0022] Figure 6B is another structural schematic diagram of a display device in an embodiment of the present disclosure;

[0023] Figure 6C It is another structural schematic diagram of the display device in the embodiment of the present disclosure.

[0024] Description of reference numerals:

[0025] 10-ultrasonic functional layer; 101-transmitting electrode layer; 102-piezoelectric material layer;

[0026] 103-receiving electrode layer; 11-control circuit layer; 21-substrate;

[0027] 22-receiving electrode; 23-sub-piezoelectric material layer; 24-transmitting electrode;

[0028] 25-planarization layer; 26-reflection layer; 61-ultrasonic fingerprint recognition device;

[0029] 62-substrate substrate; 63-driving circuit layer; 64-light emitting structure layer. DETAILED DESCRIPTION

[0030] Multiple embodiments are described herein, but the description is exemplary rather than restrictive, and there may be more embodiments and implementations within the scope of the embodiments described herein. Although many possible feature combinations are shown in the drawings and discussed in the specific embodiments, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0031] When describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps of the specific order described. As will be appreciated by those of ordinary skill in the art, other sequences of steps are also possible. Therefore, the specific sequence of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to the steps of performing them in the order written, and those skilled in the art can easily understand that these sequences can be changed and still remain within the spirit and scope of the embodiments of the present application.

[0032] Unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present disclosure should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the embodiments of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing in front of the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. In this article, "electrical connection" includes the situation where the constituent elements are connected together through an element with some electrical function. "Elements with some electrical function" are not particularly limited as long as they can transfer electrical signals between the connected constituent elements. "Elements with some electrical function" can be, for example, electrodes or wiring, or switching elements such as transistors, or other functional elements such as resistors, inductors or capacitors. "Up", "down", "left", "right", etc. are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0033] In this article, "parallel" means that the angle formed by two straight lines is greater than -10° and less than 10°, and therefore, also includes the state where the angle is greater than -5° and less than 5°. In addition, "perpendicular" means that the angle formed by two straight lines is greater than 80° and less than 100°, and therefore, also includes the state where the angle is greater than 85° and less than 95°.

[0034] In this document, "film" and "layer" can be interchanged. For example, "conductive layer" can sometimes be replaced by "conductive film". Similarly, "insulating film" can sometimes be replaced by "insulating layer".

[0035] The term "about" as used herein refers to values ​​that are not strictly limited and allow for process and measurement errors.

[0036] The "composition process (patterning process)" mentioned in the embodiments of the present disclosure includes processes such as depositing a film layer, coating a photoresist, mask exposure, development, etching, and stripping a photoresist, and is a mature preparation process in some technologies. Deposition can be carried out by known processes such as sputtering, evaporation, and chemical vapor deposition, coating can be carried out by known coating processes, and etching can be carried out by known methods, which are not limited here. In the description of the embodiments of the present disclosure, it should be understood that "thin film" refers to a thin film made by depositing or other processes of a certain material on a substrate. If the "thin film" does not require a composition process during the entire production process, the "thin film" can also be called a "layer". If the "thin film" still requires a composition process during the entire production process, it is called a "thin film" before the composition process and a "layer" after the composition process. The "layer" after the composition process contains at least one "pattern".

[0037] The present disclosure is described below through several exemplary embodiments. In order to keep the following description of the embodiments of the present disclosure clear and concise, detailed descriptions of known functions and known components (elements) may be omitted. When any part (element) of the embodiments of the present disclosure appears in more than one figure, the part (element) is represented by the same or similar reference numeral in each figure.

[0038] In some technologies, such as Figure 1A As shown, the ultrasonic fingerprint recognition device may include: a transmitting electrode layer 101, a piezoelectric material layer 102, a receiving electrode layer 103 and a control circuit layer 11. The ultrasonic functional layer 10 in the ultrasonic fingerprint recognition device is a whole-layer flat structure. The inventors of the present disclosure have found that this structure will produce the following Figure 1B The overall upward plane wave shown in the figure performs fingerprint recognition in the form of a plane wave. Although the plane wave is easier to implement, the plane wave has no focusing, has low energy, and has low recognition when noise exists. Therefore, fingerprint recognition in the form of a plane wave is easily affected by the surrounding environment clutter, resulting in poor fingerprint recognition effect. For example, the control circuit layer can be a CMOS (Complementary Metal Oxide Semiconductor) circuit layer.

[0039] The embodiments of the present disclosure provide an ultrasonic fingerprint recognition device. The ultrasonic fingerprint recognition device may include: a substrate and a receiving electrode layer, a piezoelectric material layer and a transmitting electrode layer stacked in sequence on the substrate, wherein the side of the piezoelectric material layer close to the transmitting electrode layer is a curved surface structure, through which the ultrasonic signal generated by the piezoelectric material layer can be converged along the direction of the piezoelectric material layer away from the transmitting electrode layer (i.e., the curvature direction of the curved surface structure). In this way, ultrasonic focusing is achieved by optimizing the structure of the piezoelectric material layer, so that the ultrasonic wave resonates / resonates at the intersection, which can enhance the energy and intensity of the ultrasonic signal and has a higher recognition degree when noise exists. Therefore, the ultrasonic fingerprint recognition device provided by the embodiments of the present disclosure can perform fingerprint recognition in the form of ultrasonic focusing, and can improve the accuracy of fingerprint recognition.

[0040] In an exemplary embodiment, Figure 2 As shown, the piezoelectric material layer includes: a plurality of sub-piezoelectric material layers 23, the receiving electrode layer includes: a plurality of receiving electrodes 22, and the transmitting electrode layer includes: a plurality of receiving electrodes 24. Then, the ultrasonic fingerprint recognition device may include: a substrate 21 and a plurality of receiving electrodes 22, a plurality of sub-piezoelectric material layers 23 and a plurality of transmitting electrodes 24 stacked on the substrate 21 in sequence. Here, as Figure 3 As shown, after the sub-piezoelectric material layer 23 is energized, the sub-piezoelectric material layer 23 will convert the electrical signal into an ultrasonic signal. Since the side of each sub-piezoelectric material layer 23 close to the transmitting electrode 24 is a curved surface structure, the ultrasonic signal emitted by each sub-piezoelectric material layer 23 will converge along the curvature direction of the curved surface structure (i.e., the direction close to the substrate 21 and the direction away from the transmitting electrode 24), and resonate / resonate at the intersection thereof, so that the sound wave intensity of the ultrasonic signal emitted by each sub-piezoelectric material layer 23 can be enhanced. Thus, the influence of the surrounding environmental clutter of the ultrasonic fingerprint recognition device on the ultrasonic signal it emits can be reduced. Furthermore, the fingerprint recognition accuracy of the ultrasonic fingerprint recognition device can be improved.

[0041] In an exemplary embodiment, the substrate may include a contact surface configured to be close to the contact with the fingerprint. When the fingerprint contacts the contact surface, the ultrasonic fingerprint recognition device can recognize the fingerprint by emitting an ultrasonic signal to the fingerprint and receiving the ultrasonic signal (echo) reflected by the fingerprint. Of course, the embodiments of the present disclosure include but are not limited to this. For example, when the ultrasonic fingerprint recognition device is used for a display device, the substrate may be a cover plate of the display device. The transmitting electrode layer applies voltage to the piezoelectric material layer, and the piezoelectric material layer can convert the electrical signal into an ultrasonic signal. When the finger presses the cover plate of the display device, the ridge of the fingerprint is in direct contact with the cover plate, and there is air with a large acoustic resistance between the "valley" of the fingerprint and the cover plate. Therefore, when the ultrasonic signal is reflected by the surface of the finger, the ultrasonic intensities reflected back from the "valley" and "ridge" are different. These ultrasonic signals act on the piezoelectric material layer, so that the piezoelectric materials at different positions generate different voltage signals. These voltage signals are output to the external circuit through the receiving electrode layer and detected, so that the fingerprint image can be recognized.

[0042] In an exemplary embodiment, the side of the piezoelectric material layer close to the emitting electrode layer may include but is not limited to at least one of the curved surface structures such as a spherical structure, a cylindrical structure and a slope structure. For example, the side of at least a part of the piezoelectric material layer in the piezoelectric material layer close to the emitting electrode layer may be a spherical structure, so that the ultrasonic signal emitted by this structure can be converged at a certain point, and the intensity of the ultrasonic wave can be enhanced, which can make up for the performance limitations of the piezoelectric material (for example, polyvinylidene fluoride (PVDF) material) itself, and enhance the ultrasonic fingerprint recognition capability and accuracy. For example, the side of at least a part of the piezoelectric material layer in the piezoelectric material layer close to the emitting electrode layer may be a cylindrical structure, so that the ultrasonic signal emitted by this structure can be converged on a certain line, and the intensity of the ultrasonic wave can be enhanced, which can make up for the performance limitations of the piezoelectric material (for example, PVDF material) itself, and enhance the ultrasonic fingerprint recognition capability and accuracy.

[0043] In an exemplary embodiment, in a plane parallel to the substrate, the piezoelectric material layer may include: a plurality of sub-piezoelectric material layers, each of which has a curved surface structure on one side close to the emitting electrode layer, and the ultrasonic signal emitted by each sub-piezoelectric material layer can converge along the direction of the sub-piezoelectric material layer away from the emitting electrode layer, and resonate / resonate at the intersection, which can enhance the intensity and energy of the ultrasonic signal. In turn, the fingerprint recognition accuracy can be improved.

[0044] In an exemplary embodiment, taking the case where the multiple piezoelectric sub-layers are spherical structures as an example, the multiple piezoelectric sub-layers are arranged in an array in a plane parallel to the substrate, and each piezoelectric sub-layer is hemispherical.

[0045] In an exemplary embodiment, the radii of the spherical structures of the multiple piezoelectric material sub-layers are equal, so that the strength of the ultrasonic signals emitted and converged by different spherical structures can be kept consistent, thereby further improving the fingerprint recognition accuracy.

[0046] In an exemplary embodiment, taking the multiple sub-piezoelectric material layers as a spherical structure as an example, Figure 4A As shown, the piezoelectric material layer includes: a plurality of sub-piezoelectric material layers 23 arranged in an array along a first direction X and a second direction Y on a plane parallel to the substrate 21. Here, the first direction X intersects with the second direction Y, for example, the first direction X is perpendicular to the second direction Y. In this way, each sub-piezoelectric material layer can achieve single-point ultrasonic convergence (that is, the ultrasonic signal emitted by each sub-piezoelectric material layer can converge at a certain point to enhance the intensity of the ultrasonic wave).

[0047] In an exemplary embodiment, taking the multiple sub-piezoelectric material layers as a cylindrical structure as an example, Figure 4B As shown, in a plane parallel to the substrate 21, the piezoelectric material layer includes: a plurality of columnar sub-piezoelectric material layers 23 spaced apart along a first direction X and extending along a second direction Y, wherein the first direction X intersects with the second direction Y, for example, the first direction X is perpendicular to the second direction Y. In this way, each sub-piezoelectric material layer can achieve single-line ultrasonic convergence (that is, the ultrasonic signal emitted by each sub-piezoelectric material layer can converge on a certain line to enhance the intensity of the ultrasonic wave).

[0048] In an exemplary embodiment, Figure 4C As shown, the piezoelectric material layer may include: a first part of the piezoelectric material layer and a second part of the piezoelectric material layer, the first part of the piezoelectric material layer includes: a plurality of piezoelectric material layers 23 arranged at intervals along a first direction X on a plane parallel to the substrate and in a columnar shape extending along a second direction Y; the second part of the piezoelectric material layer includes: a plurality of piezoelectric material layers 23 arranged in an array along the first direction X and the second direction Y on a plane parallel to the substrate.

[0049] Of course, in addition to the above three exemplary embodiments, the layout of the sub-piezoelectric material layer in the piezoelectric material layer can also be other layouts. For example, the piezoelectric material layer may include: a plurality of sub-piezoelectric material layers spaced apart along the second direction Y, each sub-piezoelectric material layer is in a columnar shape extending along the first direction X, and the angle between the first direction X and the second direction Y is 45°. It can be designed according to actual conditions, and the embodiments of the present disclosure are not limited to this.

[0050] In an exemplary embodiment, the spacing between two adjacent piezoelectric material sub-layers may be about 10 μm to 100 μm (micrometers). For example, the spacing between two adjacent piezoelectric material sub-layers may be 20 μm.

[0051] In an exemplary embodiment, in a plane parallel to the substrate, a cross-sectional shape of at least one of the plurality of sub-piezoelectric material layers may be circular or rectangular.

[0052] In an exemplary embodiment, when the cross section of at least one of the plurality of sub-piezoelectric material layers parallel to the substrate is circular, the diameter of the cross section of at least one of the plurality of sub-piezoelectric material layers parallel to the substrate may be approximately 10 μm to 100 μm. For example, the diameter of the cross section of at least one of the plurality of sub-piezoelectric material layers parallel to the substrate may be approximately 60 μm, 90 μm, 100 μm, etc.

[0053] In an exemplary embodiment, in a plane perpendicular to the substrate, the cross-sectional shape of each sub-piezoelectric material layer may be an arcuate shape. For example, the cross-sectional shape of each sub-piezoelectric material layer perpendicular to the substrate is a semicircle.

[0054] In an exemplary embodiment, the thickness of the plurality of sub-piezoelectric material layers in the third direction Z (the direction perpendicular to the substrate) may be about 10 μm to 100 μm. For example, the thickness of at least one of the plurality of sub-piezoelectric material layers in the third direction Z may be about 10 μm, 30 μm, 45 μm, 50 μm, etc.

[0055] In an exemplary embodiment, the orthographic projection of each piezoelectric material sub-layer on the substrate covers the orthographic projection of the receiving electrode corresponding to the piezoelectric material sub-layer on the substrate.

[0056] In an exemplary embodiment, an orthographic projection of each piezoelectric material sub-layer on the substrate at least partially overlaps with an orthographic projection of an emitting electrode corresponding to the piezoelectric material sub-layer on the substrate.

[0057] In an exemplary embodiment, the material of the piezoelectric material layer may include, but is not limited to, one or a combination of piezoelectric materials with a relatively high piezoelectric voltage constant, such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride trifluoroethylene (PVDF-TrFE), polyvinyl chloride, polycarbonate, polyvinylidene fluoride, polymethyl methacrylate (PMMA), polytetrafluoroethylene (TEFLON), etc. For example, the material of the piezoelectric sensing layer may be PVDF material, so that an ultrasonic signal with a relatively high intensity can be generated.

[0058] In an exemplary embodiment, the piezoelectric constant d33 of the piezoelectric material may be approximately 25 to 33. Here, the "piezoelectric constant" is one of the most commonly used important parameters to characterize the performance of piezoelectric materials. It is the conversion coefficient of the piezoelectric material to convert mechanical energy into electrical energy or electrical energy into mechanical energy. It reflects the coupling relationship between the elastic (mechanical) properties and the dielectric properties of the piezoelectric material. In this way, the piezoelectric material with the above-mentioned high piezoelectric constant can make the piezoelectric material layer more sensitive.

[0059] In an exemplary embodiment, Figure 4A As shown, in a plane parallel to the substrate 21, the piezoelectric material layer may include: a plurality of sub-piezoelectric material layers 23 arranged in an array. For example, each sub-piezoelectric material layer is hemispherical, then, in a plane parallel to the substrate 21, the receiving electrode layer may include: a plurality of receiving electrodes 22 arranged in an array, wherein the plurality of receiving electrodes 22 correspond to the plurality of sub-piezoelectric material layers 23 one by one.

[0060] In an exemplary embodiment, Figure 4B As shown, taking the case where, in a plane parallel to the substrate 21, the piezoelectric material layer may include: a plurality of sub-piezoelectric material layers 23 that are spaced apart along a first direction X and are in a columnar shape extending along a second direction Y, wherein the first direction X intersects with the second direction Y, then, in a plane parallel to the substrate 21, the receiving electrode layer may include: a plurality of receiving electrodes 22 that are arranged in an array, wherein a column of receiving electrodes (i.e., a plurality of receiving electrodes 22 that are arranged in a column along the second direction Y) may correspond to one sub-piezoelectric material layer 23.

[0061] In an exemplary embodiment, in a plane parallel to the substrate, the cross-sectional shape of each receiving electrode is rectangular (eg Figure 2 as shown), trapezoid, etc.

[0062] In an exemplary embodiment, in a plane perpendicular to the substrate, the cross-sectional shape of the plurality of receiving electrodes may include but is not limited to a rectangle, a trapezoid, etc.

[0063] In an exemplary embodiment, the thickness of the plurality of receiving electrodes in the third direction Z (the direction away from the substrate) may be about 10 μm to 100 μm. For example, the thickness of the plurality of receiving electrodes may be about 10 μm.

[0064] In an exemplary embodiment, the spacing between two adjacent receiving electrodes may be about 10 μm to 100 μm. For example, the spacing between two adjacent receiving electrodes may be 30 μm.

[0065] In an exemplary embodiment, taking the case where the cross-section of the multiple receiving electrodes parallel to the substrate is rectangular, the side length of the cross-section of the multiple receiving electrodes parallel to the substrate may be about 10 μm to 100 μm. For example, the size of the cross-section of the multiple receiving electrodes parallel to the substrate may be about 40 μm*40 μm, 50 μm*50 μm, 60 μm*60 μm, etc. In this way, since the width of a valley ridge cycle of a finger is usually about 300 μm, the size of the receiving electrode is reasonably set so that a valley ridge cycle of the finger can correspond to multiple receiving electrodes for sensing, which is conducive to ensuring the clarity of fingerprint recognition, thereby ensuring the accuracy of fingerprint recognition.

[0066] In an exemplary embodiment, in a plane parallel to the substrate, the transmitting electrode layer may include: a plurality of transmitting electrodes arranged in an array, and the plurality of transmitting electrodes correspond one-to-one to the plurality of receiving electrodes.

[0067] In an exemplary embodiment, the orthographic projection of each transmitting electrode on the substrate covers the orthographic projection of the receiving electrode corresponding to the transmitting electrode on the substrate.

[0068] In an exemplary embodiment, the thickness of the plurality of emitting electrodes in the third direction Z (direction away from the substrate) may be about 10 μm to 100 μm. For example, the thickness of at least one of the plurality of emitting electrodes in the third direction Z may be about 10 μm.

[0069] In an exemplary embodiment, the spacing between two adjacent emitting electrodes may be about 10 μm to 100 μm. For example, the spacing between two adjacent emitting electrodes may be 10 μm.

[0070] In an exemplary embodiment, in a plane parallel to the substrate, a cross-sectional shape of at least one of the plurality of emitting electrodes may include but is not limited to a circle or a ring.

[0071] In an exemplary embodiment, Figure 2 As shown, in a plane perpendicular to the substrate 21, the cross-sectional shape of at least one of the multiple emitting electrodes 24 may include but is not limited to an arch shape (that is, at least one of the multiple emitting electrodes 24 has a curved surface on one side close to the piezoelectric material layer, and the other side of the emitting electrode 24 away from the piezoelectric material layer is also a curved surface).

[0072] In an exemplary embodiment, the material of the emitter electrode layer may include one or more of copper, silver and aluminum.

[0073] In an exemplary embodiment, the substrate may be a glass substrate, or a flexible transparent substrate attached to a glass substrate, and this is not limited in the embodiments of the present disclosure.

[0074] In an exemplary embodiment, the substrate may be made of materials such as polyimide (PI), polyethylene terephthalate (PET), or a surface-treated polymer soft film.

[0075] In an exemplary embodiment, Figure 2 As shown, the ultrasonic fingerprint recognition device may further include: a reflective layer 26 and a planarization layer 25, wherein the reflective layer 26 is disposed on a side of the emitting electrode layer (e.g., including a plurality of emitting electrodes 24) away from the substrate 21, and the planarization layer 25 is disposed between the reflective layer 26 and the emitting electrode layer (e.g., including a plurality of emitting electrodes 24).

[0076] In an exemplary embodiment, the reflective layer can be configured to reflect the ultrasonic signal generated by the piezoelectric material layer and propagating toward the reflective layer toward the receiving electrode layer. This is beneficial to enhance the intensity or energy of the emitted ultrasonic signal.

[0077] In an exemplary embodiment, the material of the reflective layer may be silver (Ag). Of course, the embodiments of the present disclosure include but are not limited to this. For example, the material of the reflective layer may also be other materials having the property of reflecting ultrasonic signals.

[0078] In an exemplary embodiment, the planarization layer can play a planarization role and can protect the emitter electrode in the emitter electrode layer.

[0079] In an exemplary embodiment, the material of the planarization layer may be a resin material. For example, the material of the planarization layer may be an epoxy resin. Of course, the embodiments of the present disclosure include but are not limited to this. For example, the material of the planarization layer may also be other materials such as silicon nitride (SiNx).

[0080] According to Figure 5 It can be seen from the simulation results that when the curved surface structures with different curvatures in the piezoelectric material layer focus the ultrasonic signal generated by the piezoelectric material layer, the wave intensity after focusing (i.e. the intensity of the ultrasonic signal after focusing) is greatly improved compared to the plane wave intensity (i.e. the intensity of the unfocused ultrasonic wave) when the side of the piezoelectric material layer close to the transmitting electrode layer is a planar structure. In this way, the fingerprint recognition accuracy can be improved.

[0081] In an exemplary embodiment, the specific type of the ultrasonic fingerprint recognition device is not particularly limited. For example, the ultrasonic fingerprint recognition device can be a fingerprint lock, a fingerprint recognition module of an electronic device, etc. Those skilled in the art can make corresponding choices based on the actual use environment and functional requirements of the ultrasonic fingerprint recognition device, which will not be repeated here. In addition, in addition to the above-mentioned substrate, receiving electrode layer, piezoelectric material layer and transmitting electrode layer, the ultrasonic fingerprint recognition device can also include other necessary components and structures. Taking the fingerprint lock as an example, the housing, power supply, circuit board or control module, etc. Those skilled in the art can design and supplement accordingly according to the specific type of the ultrasonic fingerprint recognition device, which will not be repeated here.

[0082] In an exemplary embodiment, in addition to the above-mentioned structure for enhancing the focused wave, the ultrasonic fingerprint recognition device may also include: a lens structure capable of realizing ultrasonic focusing. For example, the lens structure capable of realizing ultrasonic focusing may be set at any position in the direction in which the piezoelectric material layer is away from the transmitting electrode layer, and may be determined according to actual conditions. The embodiment of the present disclosure does not limit the setting position of the lens structure. In this way, through two ultrasonic focusings, the intensity of the ultrasonic signal can be greatly enhanced, thereby greatly improving the fingerprint recognition accuracy.

[0083] It can be seen from the above content that an embodiment of the present disclosure provides an ultrasonic fingerprint recognition device, which may include: a substrate and a receiving electrode layer, a piezoelectric material layer and a transmitting electrode layer stacked in sequence on the substrate, wherein the side of the piezoelectric material layer close to the transmitting electrode layer is a curved surface structure. In this way, through the curved surface structure, the ultrasonic signal generated by the piezoelectric material layer can converge along the direction of the piezoelectric material layer away from the transmitting electrode layer, and resonate / resonate at the intersection. Therefore, the intensity of the ultrasonic signal can be enhanced. Furthermore, the fingerprint recognition accuracy can be improved.

[0084] The present disclosure provides a method for preparing an ultrasonic fingerprint recognition device, which may include:

[0085] S11, forming a receiving electrode layer on a substrate.

[0086] S12, forming a piezoelectric material layer on the receiving electrode layer, wherein the side of the piezoelectric material layer close to the transmitting electrode layer is a curved structure, and the ultrasonic signal generated by the piezoelectric material layer can converge along the direction of the piezoelectric material layer away from the transmitting electrode layer, and resonate / resonate at the intersection, which can enhance the intensity and energy of the ultrasonic signal. In turn, the fingerprint recognition accuracy can be improved.

[0087] S13, forming an emitting electrode layer on the piezoelectric material layer.

[0088] In an exemplary embodiment, S11 may include: depositing a first metal film on a substrate; performing a patterning process on the first metal film to form a receiving electrode layer on the substrate, wherein the receiving electrode layer includes: a plurality of receiving electrodes arranged in an array.

[0089] In an exemplary embodiment, the first metal film can be made of metal materials, such as aluminum, copper, molybdenum, titanium, niobium, silver, gold, tantalum, tungsten, chromium and other materials, or it can be made of conductive oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In2O3), aluminum-doped zinc oxide (AlZnO), etc. It can be a single-layer structure or a multi-layer composite structure.

[0090] In an exemplary embodiment, S12 may include: depositing a PVDF film on the receiving electrode layer; performing a patterning process and a baking process on the PVDF film, and adjusting the PVDF pattern morphology so that a curved surface structure such as a spherical structure or a cylindrical structure is formed on the side of the piezoelectric material layer close to the transmitting electrode layer. In this way, the ultrasonic signal generated by the piezoelectric material layer can converge along the direction of the piezoelectric material layer away from the transmitting electrode layer, and resonate / resonate at the intersection, which can enhance the intensity and energy of the ultrasonic signal. In turn, the fingerprint recognition accuracy can be improved.

[0091] In an exemplary embodiment, S13 may include: depositing a second metal film on the substrate; performing a patterning process on the second metal film to form an emitter electrode layer on the piezoelectric material layer, wherein the emitter electrode layer includes: a plurality of emitter electrodes arranged in an array.

[0092] In an exemplary embodiment, the second metal film can be a mixture of one or more metal materials such as aluminum, copper, molybdenum, niobium, titanium, silver, gold, tantalum, tungsten, chromium, etc., and can be a single-layer, double-layer or multi-layer structure, and can be deposited by radio frequency magnetron sputtering.

[0093] In an exemplary embodiment, after S13, the preparation method may further include:

[0094] S14, forming a planarization layer covering the emitter electrode layer;

[0095] S15. Form a reflective layer on the planarization layer.

[0096] The embodiments of the present disclosure also provide a display device, including a display panel and the ultrasonic fingerprint recognition device in one or more of the above embodiments, wherein the ultrasonic fingerprint recognition device is arranged on the non-light-emitting surface of the display panel. Here, the layout of the ultrasonic fingerprint recognition device in the display device can be designed according to actual needs, and the embodiments of the present disclosure do not limit this.

[0097] In an exemplary embodiment, the display panel may include, but is not limited to, any one of an organic light-emitting diode (OLED) display panel, a quantum dot light-emitting diode (QLED) display panel, and an inorganic light-emitting diode display panel. For example, the display panel may be a Micro-LED display panel, a Mini-LED display panel, and the like.

[0098] For example, taking the display panel as an OLED display panel, the display device may include: an OLED display panel and an ultrasonic fingerprint recognition device arranged on the non-light emitting surface side of the OLED display panel.

[0099] In an exemplary embodiment, the display device can be: a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator, or any other product or component with a display function. The disclosed embodiment does not limit the type of display device. Those skilled in the art can make corresponding choices based on the actual use requirements of the display device, which will not be repeated here. It should be noted that in addition to the display panel and the ultrasonic fingerprint recognition device in one or more of the above embodiments, the display device may also include other necessary components and structures. Taking the display screen as an example, such as a housing, a control circuit board, a power cord, etc., those skilled in the art can make corresponding supplements based on the function of the display device, which will not be repeated here.

[0100] In an exemplary embodiment, the ultrasonic fingerprint recognition device provided by the embodiment of the present disclosure can be directly combined with the backplane structure in the display panel to form an In-cell structure. The location of the ultrasonic fingerprint recognition device in the In-cell structure can be designed according to actual needs, and the embodiment of the present disclosure does not limit this. For example, the ultrasonic fingerprint recognition device provided by the embodiment of the present disclosure can be manufactured on the backplane structure after the backplane structure manufacturing process is completed; or, the structure of the ultrasonic fingerprint recognition device provided by the embodiment of the present disclosure can be preferentially manufactured before the backplane structure manufacturing process is completed, and the signal can be led out by means of leads or the like; or, the ultrasonic fingerprint recognition device provided by the embodiment of the present disclosure can also be manufactured in the backplane film layer. This structure can effectively improve the integration of the backplane process, improve the value of the backplane, and improve the yield. Avoid yield and process problems introduced by subsequent bonding processes.

[0101] In an exemplary embodiment, the display panel may include: a base substrate, a backplane structure layer and a light emitting structure layer stacked in sequence, and the ultrasonic fingerprint recognition device is arranged between the backplane structure layer and the light emitting structure layer. Fig. 6A As shown, the backplane structure layer may include: a driving circuit layer 63, the driving circuit layer 63 is arranged on the base substrate 62; the ultrasonic fingerprint recognition device 61 is arranged on the side of the driving circuit layer 63 away from the base substrate 62; and the light emitting structure layer 64 is arranged on the side of the ultrasonic fingerprint recognition device 61 away from the base substrate. In this way, the ultrasonic fingerprint recognition device can be manufactured on the backplane structure after the manufacturing process of the backplane structure is completed. For example, the ultrasonic fingerprint recognition device can be manufactured on the driving circuit layer after the manufacturing process of the driving circuit layer is completed.

[0102] In an exemplary embodiment, the display panel may include: a base substrate, a backplane structure layer and a light emitting structure layer stacked in sequence, and the ultrasonic fingerprint recognition device is arranged between the base substrate and the backplane structure layer. Figure 6BAs shown, the ultrasonic fingerprint recognition device 61 is arranged on the base substrate 62; the back plate structure layer may include: a driving circuit layer 63, the driving circuit layer 63 is arranged on the side of the ultrasonic fingerprint recognition device 61 away from the base substrate 62; and the light emitting structure layer 64 is arranged on the side of the driving circuit layer 63 away from the base substrate 62. In this way, the ultrasonic fingerprint recognition device is arranged under the back plate structure layer, and the structure of the ultrasonic fingerprint recognition device can be preferentially manufactured before the back plate structure layer manufacturing process, and the signal can be led out by means of leads, etc. For example, the structure of the ultrasonic fingerprint recognition device can be preferentially manufactured before the driving circuit layer is manufactured, and the signal can be led out by means of leads, etc.

[0103] In an exemplary embodiment, the display panel may include: a base substrate, a backplane structure layer and a light emitting structure layer stacked in sequence, and the ultrasonic fingerprint recognition device is disposed in the backplane structure layer. Figure 6C As shown, the backplane structure layer includes: a driving circuit layer 63; the driving circuit layer 63 is arranged on the base substrate 62; the ultrasonic fingerprint recognition device 61 is arranged in the driving circuit layer 63, and the light emitting structure layer 64 is arranged on the side of the driving circuit layer 63 away from the base substrate 62. In this way, the ultrasonic fingerprint recognition device is made in the film layer structure of the backplane structure, for example, the ultrasonic fingerprint recognition device is made in the film layer structure of the driving circuit layer, which can not only effectively improve the backplane process integration, improve the backplane value, and improve the yield, but also avoid the yield and process problems introduced by the subsequent bonding process.

[0104] For example, taking the display panel as an OLED display panel as an example, the driving circuit layer may be a TFT (Thin Film Transistor) device layer, and the light-emitting structure layer may be an OLED light-emitting device layer. For example, the OLED light-emitting device layer may include a plurality of OLED light-emitting elements, and the TFT device layer may include a plurality of TFTs coupled to the plurality of light-emitting elements, which are respectively used to drive the light-emitting elements formed subsequently. The circuit structure and layout of the driving circuit layer may be designed according to actual needs, and the embodiments of the present disclosure are not limited to this. For example, the driving circuit layer may also include various routings such as scanning signal lines and data signal lines, and the present disclosure is not limited to this.

[0105] For example, the ultrasonic fingerprint recognition device includes a plurality of fingerprint recognition elements (eg, composed of at least one transmitting electrode, at least one sub-piezoelectric material layer and at least one receiving electrode), and each fingerprint recognition element is disposed between two TFTs.

[0106] For example, the transistors in the TFT device layer all include a gate electrode G, a source electrode S, and a drain electrode D. For example, the three electrodes are electrically connected to three electrode connecting portions, for example, through vias filled with tungsten metal (i.e., tungsten vias, W-vias); furthermore, the three electrodes can be electrically connected to other electrical structures (e.g., transistors, traces, light-emitting elements, etc.) through corresponding electrode connecting portions.

[0107] For example, the substrate and the driving circuit layer can be manufactured by a front-end wafer factory through processing of a single crystal silicon wafer.

[0108] For example, each light-emitting element may include a first electrode (for example, as an anode), an organic light-emitting functional layer, and a second electrode (for example, as a cathode) stacked in sequence. For example, the first electrode may be electrically connected to the source electrode S of the transistor in the corresponding TFT device layer through a tungsten via (via the connection portion corresponding to the source electrode S). It is understandable that the positions of the source electrode S and the drain electrode D may be interchanged, that is, the first electrode may also be replaced to be electrically connected to the drain electrode D. For example, the organic light-emitting functional layer may include an organic light-emitting layer, and may also include one or more of an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer. For example, the second electrode is a transparent electrode; for example, the second electrode is a common electrode, that is, a plurality of light-emitting elements share a whole surface of the second electrode.

[0109] The technical effects of the display device provided by at least one embodiment of the present disclosure can be referred to the corresponding description of the ultrasonic fingerprint recognition device in the above embodiments, which will not be repeated here.

[0110] Although the embodiments disclosed in the present disclosure are as above, the contents described are only embodiments adopted to facilitate understanding of the present disclosure and are not intended to limit the present disclosure. Any technician in the field to which the present disclosure belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present disclosure, but the scope of patent protection of this application shall still be subject to the scope defined in the attached claims.

Claims

1. An ultrasonic fingerprint recognition device, characterized in that: include: A substrate and a receiving electrode layer, a piezoelectric material layer and a transmitting electrode layer sequentially stacked on the substrate, wherein: The side of the piezoelectric material layer close to the transmitting electrode layer is a curved structure, and the ultrasonic signal generated by the piezoelectric material layer can be converged in a direction away from the transmitting electrode layer to enhance the strength of the ultrasonic signal; in a plane parallel to the substrate, the piezoelectric material layer includes: a plurality of sub-piezoelectric material layers arranged in an array, and the receiving electrode layer includes: a plurality of receiving electrodes arranged in an array, and the plurality of receiving electrodes correspond one-to-one to the plurality of sub-piezoelectric material layers; in a plane perpendicular to the substrate, the cross-sectional shape of each receiving electrode is rectangular; the side length of the cross-sectional area of ​​each receiving electrode parallel to the substrate is 10μm to 100μm.

2. The ultrasonic fingerprint recognition device according to claim 1, characterized in that: The curved surface structure is at least one of a spherical structure, a cylindrical structure and a slope structure.

3. The ultrasonic fingerprint recognition device according to claim 1, characterized in that: Each sub-piezoelectric material layer is hemispherical.

4. The ultrasonic fingerprint recognition device according to claim 1, characterized in that: In a plane parallel to the substrate, the piezoelectric material layer includes: a plurality of sub-piezoelectric material layers spaced apart along a first direction, each sub-piezoelectric material layer is in a column shape extending along a second direction, wherein the first direction intersects the second direction.

5. The ultrasonic fingerprint recognition device according to claim 3 or 4, characterized in that: In a plane perpendicular to the substrate, a cross-section of each piezoelectric material sub-layer is arcuate.

6. The ultrasonic fingerprint recognition device according to claim 1 or 4, characterized in that: In a plane parallel to the substrate, the transmitting electrode layer includes: a plurality of transmitting electrodes arranged in an array, and the plurality of transmitting electrodes correspond one-to-one to the plurality of receiving electrodes.

7. The ultrasonic fingerprint recognition device according to claim 6, characterized in that: In a plane perpendicular to the substrate, a cross-section of each emitting electrode is an arch.

8. The ultrasonic fingerprint recognition device according to claim 6, characterized in that: The orthographic projection of each piezoelectric sub-layer on the substrate covers the orthographic projection of the receiving electrode corresponding to the piezoelectric sub-layer on the substrate; the orthographic projection of each piezoelectric sub-layer on the substrate at least partially overlaps with the orthographic projection of the transmitting electrode corresponding to the piezoelectric sub-layer on the substrate.

9. The ultrasonic fingerprint recognition device according to claim 1, characterized in that: Also includes: A reflective layer and a planarization layer, wherein a reflective layer, disposed on a side of the transmitting electrode layer away from the piezoelectric material layer, and configured to reflect the ultrasonic signal generated by the piezoelectric material layer and propagating toward the reflective layer toward the receiving electrode layer; The planarization layer is disposed between the reflective layer and the emitting electrode layer and is configured to protect the emitting electrode layer.

10. A display device, characterized in that: include: A display panel and an ultrasonic fingerprint recognition device as claimed in any one of claims 1 to 9, wherein the ultrasonic fingerprint recognition device is arranged on a non-light-emitting surface of the display panel.

11. The display device according to claim 10, characterized in that: The display panel comprises: a base substrate, a backplane structure layer and a light emitting structure layer stacked in sequence, wherein: The ultrasonic fingerprint recognition device is arranged between the back plate structure layer and the light emitting structure layer; or, the ultrasonic fingerprint recognition device is arranged between the base substrate and the back plate structure layer; or, the ultrasonic fingerprint recognition device is arranged in the back plate structure layer.

12. A method for preparing an ultrasonic fingerprint recognition device, characterized in that: include: forming a receiving electrode layer on the substrate; A piezoelectric material layer is formed on the receiving electrode layer, wherein the side of the piezoelectric material layer close to the transmitting electrode layer is a curved structure, and the ultrasonic signal generated by the piezoelectric material layer can be converged in a direction away from the transmitting electrode layer to enhance the strength of the ultrasonic signal; in a plane parallel to the substrate, the piezoelectric material layer includes: a plurality of sub-piezoelectric material layers arranged in an array, and the receiving electrode layer includes: a plurality of receiving electrodes arranged in an array, and the plurality of receiving electrodes correspond to the plurality of sub-piezoelectric material layers one by one; in a plane perpendicular to the substrate, the cross-sectional shape of each receiving electrode is rectangular; the side length of the cross-sectional area of ​​each receiving electrode parallel to the substrate is 10 μm to 100 μm; The emitter electrode layer is formed on the piezoelectric material layer.

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