Ultrasonic transducer substrate and manufacturing method therefor, and device

Abstract

Embodiments of the present disclosure disclose an ultrasonic transducer substrate and a manufacturing method therefor, and a device. An ultrasonic transmitting structure can transmit ultrasonic waves, and an ultrasonic receiving structure can receive ultrasonic waves. Compared with an integrated transmitting and receiving structure in the prior art, transmitting and receiving structures provided separately in the present disclosure can be independently controlled, such that targeted design of the materials and structures of both the ultrasonic transmitting structure and the ultrasonic receiving structure can be achieved, thereby facilitating enhancement of the working performance of the ultrasonic transmitting structure and the ultrasonic receiving structure. Moreover, in the present disclosure, the ultrasonic receiving structure surrounds the ultrasonic transmitting structure, such that reflected ultrasonic signals are prevented from causing crosstalk to the ultrasonic receiving structure, signal noise is reduced, and the signal-to-noise ratio is increased, thereby improving imaging quality and clarity.

Description

Ultrasonic transducer substrate and manufacturing method and equipment thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on June 13, 2023, with application number 202310700741.X and invention name "An ultrasonic transducer substrate and its manufacturing method and equipment", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present disclosure relates to the field of ultrasonic detection technology, and in particular to an ultrasonic transducer substrate and a manufacturing method and equipment thereof. Background Art

[0004] A micromachined ultrasonic transducer (MUT) is a type of MEMS (Micro-Electro-Mechanical System) device that uses electrical effects to vibrate a piezoelectric film, thereby transmitting or receiving ultrasonic signals. These include PMUTs (Piezoelectric Micromachined Ultrasonic Transducers) and CMUTs (Capacitance Micromachined Ultrasonic Transducers).

[0005] The above two micromechanical ultrasonic transducers can bring revolutionary changes to ultrasonic imaging technology.

[0006] Summary of the Invention

[0007] The present disclosure provides an ultrasonic transducer substrate and a manufacturing method and device thereof. The specific solution is as follows:

[0008] An ultrasonic transducer substrate provided in an embodiment of the present disclosure includes a base substrate and a plurality of ultrasonic transducer units arranged on the base substrate, wherein the ultrasonic transducer units include:

[0009] an ultrasonic transmitting structure configured to convert a received electrical signal into an ultrasonic signal;

[0010] an ultrasonic receiving structure, wherein the orthographic projection of the ultrasonic receiving structure on the base substrate surrounds the orthographic projection of the ultrasonic transmitting structure on the base substrate, and the ultrasonic receiving structure is configured to convert a received ultrasonic signal into an electrical signal and output the electrical signal;

[0011] A driving circuit is provided between the base substrate and the ultrasonic receiving structure, and the driving circuit is electrically connected to the ultrasonic receiving structure. The driving circuit is configured to receive an electrical signal output by the ultrasonic receiving structure.

[0012] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the ultrasonic emitting structure includes:

[0013] a cavity, disposed close to the substrate;

[0014] a first passivation layer, disposed on a side of the cavity facing away from the base substrate, wherein an orthographic projection of the first passivation layer on the base substrate covers an orthographic projection of the cavity on the base substrate;

[0015] a first electrode, disposed on a side of the first passivation layer facing away from the substrate, the first electrode being configured to receive a driving voltage;

[0016] A first piezoelectric structure is provided on a side of the first electrode facing away from the substrate;

[0017] The second electrode is arranged on a side of the first piezoelectric structure away from the substrate, and the second electrode is grounded.

[0018] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the ultrasonic transmitting structure further includes an etched hole connected to the cavity, and the orthographic projection of the first passivation layer on the base substrate does not overlap with the orthographic projection of the etched hole on the base substrate.

[0019] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the orthographic projection shape of the first passivation layer on the base substrate is the same as the orthographic projection shape of the cavity on the base substrate.

[0020] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, a ratio of the size of the first passivation layer to the size of the cavity is greater than or equal to 1.2 and less than or equal to 1.5.

[0021] In a possible implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, a plurality of ultrasonic transducer units are distributed in an array on the base substrate; wherein,

[0022] The etching holes corresponding to the cavities are independently arranged, or the etching holes corresponding to the cavities in the same row are connected to each other.

[0023] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the orthographic projection shape of the first electrode on the base substrate includes a circle or a square.

[0024] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the ultrasonic receiving structure includes:

[0025] a third electrode, the third electrode being spaced apart from the first electrode, the third electrode and the first electrode being located on the same side of the cavity, the orthographic projection of the third electrode on the substrate surrounding the orthographic projection of the first electrode on the substrate, and the third electrode being electrically connected to the driving circuit;

[0026] A second piezoelectric structure is provided on a side of the third electrode facing away from the substrate;

[0027] A fourth electrode is provided on a side of the second piezoelectric structure away from the base substrate, and the fourth electrode is grounded.

[0028] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the first electrode and the third electrode are provided in the same layer.

[0029] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the first electrode and the third electrode are provided in different layers, and a second passivation layer is provided between the first electrode and the third electrode.

[0030] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the first electrode is disposed close to the base substrate, or the third electrode is disposed close to the base substrate.

[0031] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the second electrode and the fourth electrode are an integral structure arranged on the entire surface, and the first piezoelectric structure and the second piezoelectric structure are an integral structure arranged on the entire surface.

[0032] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the second electrode and the fourth electrode are spaced apart, and the orthographic projection of the fourth electrode on the base substrate surrounds the orthographic projection of the second electrode on the base substrate;

[0033] The first piezoelectric structure and the second piezoelectric structure are spaced apart, and an orthographic projection of the second piezoelectric structure on the base substrate surrounds an orthographic projection of the first piezoelectric structure on the base substrate.

[0034] In a possible implementation, the ultrasonic transducer substrate provided in an embodiment of the present disclosure further includes: a third passivation layer arranged on the entire surface between the first electrode and / or the third electrode and the first piezoelectric structure, and an organic layer arranged on the entire surface between the first electrode and / or the third electrode and the first passivation layer.

[0035] In a possible implementation, the ultrasonic transducer substrate provided in the embodiment of the present disclosure further includes a first bonding electrode that is in the same layer as the cavity and is spaced apart from the cavity, the third electrode is electrically connected to the first bonding electrode, and the first bonding electrode is electrically connected to the driving circuit; wherein,

[0036] The cavity and the periphery of the first bonding electrode are filled with a resin layer.

[0037] In a possible implementation, in the ultrasonic transducer substrate provided in an embodiment of the present disclosure, the material of the first piezoelectric structure and the material of the second piezoelectric structure include polyvinylidene fluoride.

[0038] Correspondingly, an embodiment of the present disclosure further provides a device, comprising the above-mentioned ultrasonic transducer substrate provided by an embodiment of the present disclosure.

[0039] Accordingly, the embodiment of the present disclosure further provides a method for manufacturing an ultrasonic transducer substrate, which is used to manufacture the ultrasonic transducer substrate provided in the embodiment of the present disclosure. The manufacturing method includes:

[0040] providing a substrate;

[0041] forming a plurality of ultrasonic transducer units on one side of the base substrate;

[0042] Forming the ultrasonic transducer unit includes:

[0043] forming a driving circuit on one side of the base substrate;

[0044] An ultrasonic transmitting structure and an ultrasonic receiving structure are formed on the side of the driving circuit facing away from the base substrate. The driving circuit is electrically connected to the ultrasonic receiving structure, and the orthographic projection of the ultrasonic receiving structure on the base substrate surrounds the orthographic projection of the ultrasonic transmitting structure on the base substrate. The ultrasonic transmitting structure is configured to convert the received electrical signal into an ultrasonic signal, the ultrasonic receiving structure is configured to convert the received ultrasonic signal into an electrical signal and then output it, and the driving circuit is configured to receive the electrical signal output by the ultrasonic receiving structure.

[0045] In a possible implementation, in the above-mentioned manufacturing method provided in an embodiment of the present disclosure, the ultrasonic transmitting structure includes a cavity, a first passivation layer, a first electrode, a first piezoelectric structure, and a second electrode stacked in sequence; wherein forming the cavity includes:

[0046] forming a metal film on a side away from the substrate, wherein the metal film includes a cavity area, a non-cavity area and an etched hole area, and the etched hole area is connected to the cavity area;

[0047] Etching the non-cavity area to remove metal from the non-cavity area;

[0048] Filling a resin layer in the non-cavity area where the metal is removed;

[0049] forming a first passivation layer on a side of the cavity region facing away from the base substrate, and etching the first passivation layer so that an orthographic projection of the first passivation layer on the base substrate covers an orthographic projection of the cavity region on the base substrate, and the orthographic projection of the first passivation layer on the base substrate does not overlap with an orthographic projection of the etched hole region on the base substrate;

[0050] An etching solution is injected into the etched hole area, and the cavity area is etched to remove the metal in the cavity area to form the cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG1 is a schematic structural diagram of an ultrasonic transducer substrate provided in an embodiment of the present disclosure;

[0052] FIG2 is a schematic diagram of another structure of an ultrasonic transducer substrate provided in an embodiment of the present disclosure;

[0053] FIG3 is a schematic diagram of another structure of an ultrasonic transducer substrate provided in an embodiment of the present disclosure;

[0054] FIG4 is a schematic diagram of another structure of an ultrasonic transducer substrate provided in an embodiment of the present disclosure;

[0055] FIG5 is a schematic diagram of another structure of an ultrasonic transducer substrate provided in an embodiment of the present disclosure;

[0056] FIG6 is a schematic diagram of another structure of an ultrasonic transducer substrate provided in an embodiment of the present disclosure;

[0057] FIG7 is a plan view of a first electrode and a third electrode;

[0058] FIG8 is another schematic plan view of the first electrode and the third electrode;

[0059] FIG9 is a plan view of a cavity in a plurality of ultrasonic transducer units;

[0060] FIG10 is another schematic plan view of the cavities in the plurality of ultrasonic transducer units;

[0061] FIG11 is a schematic diagram of the ultrasonic imaging principle of the ultrasonic transducer substrate provided in an embodiment of the present disclosure;

[0062] FIG12 is a schematic diagram of a process flow of a method for manufacturing an ultrasonic transducer substrate according to an embodiment of the present disclosure;

[0063] FIG13 is a second flow chart of a method for manufacturing an ultrasonic transducer substrate according to an embodiment of the present disclosure;

[0064] 14A-14I are schematic structural diagrams of the ultrasonic transducer substrate after each step is performed in the manufacturing of the ultrasonic transducer substrate according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. And in the absence of conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0066] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words “include” or “comprise” and the like used in this disclosure mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The words “connect” or “connected” and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Inside”, “outside”, “upper”, “lower”, etc. are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0067] It should be noted that the sizes and shapes of the figures in the accompanying drawings do not reflect the actual scale and are only for the purpose of illustrating the present disclosure. The same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions.

[0068] In the related art, three mainstream micromechanical ultrasonic transducer device structures include PMUT, CMUT and sandwich-structured ultrasonic imaging devices.

[0069] Among them, the ultrasonic imaging principle of CMUT is to use the difference in capacitance between upper and lower electrodes with a certain distance between them, so that the diaphragm located between the two relies on electrostatic attraction to drive the sound. The distance between the upper and lower electrodes needs to be designed. The distance cannot be too large, otherwise the electrostatic attraction will not be increased, which makes the preparation of micromechanical devices more difficult.

[0070] The ultrasonic imaging principle of PMUT and sandwich structures utilizes the direct piezoelectric effect and inverse piezoelectric effect of piezoelectric materials. When a certain voltage is applied to the piezoelectric material, the piezoelectric material deforms and vibrates, thereby generating ultrasonic waves. This phenomenon is the inverse piezoelectric effect of the piezoelectric material. When a certain force (ultrasound) is applied to the piezoelectric material, the piezoelectric material deforms and generates electric charges on the surface of the material, thereby converting ultrasonic waves into electrical signals. This phenomenon is the direct piezoelectric effect of the piezoelectric material. However, for the sandwich structure, the vibration mode of the piezoelectric layer of the sandwich structure is a vibration along the thickness direction (that is, there is no cavity). The intensity of the ultrasonic signal is generally increased by increasing the excitation voltage when transmitting the ultrasonic signal. However, increasing the excitation voltage not only increases power consumption, but also easily causes the piezoelectric layer to lose its piezoelectric properties due to breakdown.

[0071] However, most ultrasonic imaging devices in related technologies are designed with an integrated transmitter and receiver, and basically adopt a sandwich structure. This device structure not only has low signal transmission intensity, but also weak signal intensity reaching the device after reflection. It also easily causes crosstalk between the reflected ultrasonic signals between the various oscillators, increasing noise, reducing the signal-to-noise ratio, and ultimately affecting the imaging quality.

[0072] In view of this, an embodiment of the present disclosure provides an ultrasonic transducer substrate, as shown in FIG1 to FIG6 , including a base substrate 1 and a plurality of ultrasonic transducer units P disposed on the base substrate 1, wherein the ultrasonic transducer units P include:

[0073] The ultrasonic transmitting structure 2 is configured to convert the received electrical signal into an ultrasonic signal;

[0074] an ultrasonic receiving structure 3, wherein the orthographic projection of the ultrasonic receiving structure 3 on the substrate 1 surrounds the orthographic projection of the ultrasonic transmitting structure 2 on the substrate 1, and the ultrasonic receiving structure 3 is configured to convert the received ultrasonic signal into an electrical signal and output the electrical signal;

[0075] The driving circuit 4 is provided between the base substrate 1 and the ultrasonic receiving structure 3 , and the driving circuit 1 is electrically connected to the ultrasonic receiving structure 3 . The driving circuit 4 is configured to receive the electrical signal output by the ultrasonic receiving structure 3 .

[0076] The above-mentioned ultrasonic transducer substrate provided in the embodiment of the present disclosure has an ultrasonic transmitting structure that can transmit ultrasonic waves, and an ultrasonic receiving structure that can receive ultrasonic waves. Compared with the structure in which transmitting and receiving are integrated in the related art, the structure in which transmitting and receiving are separately arranged in the present disclosure can be independently controlled, so that the materials and structures of the ultrasonic transmitting structure and the ultrasonic receiving structure can be designed in a targeted manner, thereby facilitating the improvement of the working performance of the ultrasonic transmitting structure and the ultrasonic receiving structure; and, the present disclosure adopts an ultrasonic receiving structure to surround the ultrasonic transmitting structure, which can avoid the reflected ultrasonic signal from causing crosstalk between the ultrasonic receiving structures, reduce the noise of the signal, and improve the signal-to-noise ratio, thereby improving the imaging quality and clarity.

[0077] Optionally, the substrate 1 may be a flexible substrate, such as a substrate made of flexible materials such as polyimide, or a rigid substrate such as glass, quartz or silicon.

[0078] Specifically, as shown in Figures 1 to 6, the driving circuit 4 includes a thin film transistor, which includes: an active layer Act disposed between the base substrate 1 and the ultrasonic receiving structure 3, a gate G disposed between the active layer Act and the ultrasonic receiving structure 3, and a source S and a drain D disposed between the gate G and the ultrasonic receiving structure 3. The ultrasonic transducer substrate also includes: a first bonding electrode 5 disposed between the source S, the drain D and the ultrasonic receiving structure 3, and a second bonding electrode 6 disposed between the first bonding electrode 5 and the source S, the drain D; one side of the second bonding electrode 6 is electrically connected to the source S or the drain D of the thin film transistor (this disclosure takes the electrical connection of the second bonding electrode 6 to the source S as an example), and the other side of the second bonding electrode 6 is electrically connected to one side of the first bonding electrode 5, and the other side of the first bonding electrode 5 is electrically connected to the ultrasonic receiving structure 3.

[0079] Specifically, as shown in Figures 1 to 6, the ultrasonic transducer substrate also includes: a buffer layer 7 arranged between the base substrate 1 and the active layer Act, a barrier layer 8 arranged between the buffer layer 7 and the active layer Act, a gate insulating layer 9 arranged between the active layer Act and the gate G, an interlayer insulating layer 10 arranged between the gate G and the source S and the drain D, a flat layer 11 arranged between the source S, the drain D and the second strapping electrode 6, and a fourth passivation layer 12 arranged between the first strapping electrode 5 and the second strapping electrode 6; wherein the source S and the drain D are electrically connected to the active layer Act through vias penetrating the interlayer insulating layer 10 and the gate insulating layer 9, respectively, the second strapping electrode 6 is electrically connected to the source S through a via penetrating the flat layer 11, and the first strapping electrode 5 is electrically connected to the second strapping electrode 6 through a via penetrating the fourth passivation layer 12.

[0080] Optionally, the first bonding electrode 5 and the second bonding electrode 6 may be metal electrodes.

[0081] Specifically, as shown in Figures 1 to 6, each driving circuit 4 in the embodiment of the present disclosure only has one thin film transistor. In the specific device structure, the circuit structure of the driving circuit 4 corresponding to the ultrasound receiving structure 3 can be a 3T1C structure or a 4T1C structure, and its thin film transistor can be an LTPS structure or an LTPO structure.

[0082] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, as shown in FIG1 to FIG6 , the ultrasonic emitting structure 2 may include:

[0083] The cavity 21 is arranged close to the substrate 1;

[0084] A first passivation layer 22 is provided on a side of the cavity 21 facing away from the base substrate 1 , and an orthographic projection of the first passivation layer 22 on the base substrate 1 covers an orthographic projection of the cavity 21 on the base substrate 1 ;

[0085] A first electrode 23 is provided on a side of the first passivation layer 22 facing away from the substrate 1 , and the first electrode 23 is configured to receive a driving voltage;

[0086] The first piezoelectric structure 24 is provided on a side of the first electrode 23 facing away from the substrate 1;

[0087] The second electrode 25 is disposed on a side of the first piezoelectric structure 24 facing away from the substrate 1 , and the second electrode 25 is grounded.

[0088] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, as shown in FIG1-6 , the first bonding electrode 5 can be arranged in the same layer as the cavity 21 and spaced apart, and the periphery of the cavity 21 and the first bonding electrode 5 can be filled with a resin layer 13 .

[0089] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, as shown in FIG1 to FIG6 , the ultrasonic receiving structure 3 may include:

[0090] a third electrode 31, the third electrode 31 being spaced apart from the first electrode 23, the third electrode 31 and the first electrode 23 being located on the same side of the cavity 21, and the orthographic projection of the third electrode 31 on the base substrate 1 surrounding the orthographic projection of the first electrode 23 on the base substrate 1, and the third electrode 31 being electrically connected to the driving circuit 4; specifically, the third electrode 31 being electrically connected to the first strapping electrode 5, that is, the third electrode 31 being electrically connected to the source electrode S of the thin film transistor in the driving circuit 4 via the first strapping electrode 5 and the second strapping electrode 6;

[0091] The second piezoelectric structure 32 is provided on a side of the third electrode 31 facing away from the substrate 1;

[0092] The fourth electrode 33 is disposed on a side of the second piezoelectric structure 32 facing away from the substrate 1 , and the fourth electrode 33 is grounded.

[0093] Specifically, as shown in Figures 1 to 6, the ultrasonic transmitting structure 2 is a PMUT structure, and the ultrasonic receiving structure 3 is a sandwich structure. Such a device structure can not only enhance the emission intensity of the ultrasonic signal and improve the imaging quality, but also allow the transmitting and receiving ICs to be set separately and controlled independently.

[0094] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, as shown in FIG7 , FIG7 is a plan view schematic diagram of the first electrode 23 and the third electrode 31, wherein the orthographic projection of the first electrode 23 on the substrate 1 is a circle, and the orthographic projection of the third electrode 31 on the substrate 1 is a ring; as shown in FIG8 , FIG8 is another plan view schematic diagram of the first electrode 23 and the third electrode 31, wherein the orthographic projection of the first electrode 23 on the substrate 1 is a square, and the orthographic projection of the third electrode 31 on the substrate 1 is a square ring. The concentric ring design of the first electrode 23 and the third electrode 31 can avoid the occurrence of crosstalk between different ultrasonic receiving structures 3 of the reflected ultrasonic signals, reduce signal noise, and thus improve imaging quality.

[0095] Optionally, the material of each of the electrodes may be a metal material with conductive properties, such as gold, molybdenum, nickel, etc., which may be formed by sputtering, electroplating, and other processes in the prior art.

[0096] Specifically, as shown in Figures 1-6, the first electrode 23 and the second electrode 25 are used to provide an electrical signal to the first piezoelectric structure 24. The first piezoelectric structure 24 deforms under the action of the electrical signal (inverse piezoelectric effect). The cavity 21 provides vibration when the first piezoelectric structure 24 deforms, thereby generating ultrasonic waves. As a result, the ultrasonic transmitting structure 2 generates and transmits ultrasonic signals based on the electrical signal. The second piezoelectric structure 32 deforms when it receives the ultrasonic signal, which in turn causes the third electrode 31 to have an electric charge (positive piezoelectric effect), thereby generating an electrical signal to the drive circuit 4. As a result, the ultrasonic receiving structure 3 generates an electrical signal based on the received ultrasonic signal.

[0097] Specifically, as shown in Figures 1-6 , the ultrasonic emitting structure 2 of the disclosed embodiment is provided with a cavity 21, which allows the first piezoelectric structure 24 to vibrate in a cantilever-like manner. This cantilever-like vibration has a larger amplitude and generates a stronger ultrasonic signal. Compared to the sandwich structure vibration along the thickness of the piezoelectric layer in related technologies, this cantilever-like vibration can further enhance the ultrasonic signal strength.

[0098] Optionally, the materials of the first piezoelectric structure 24 and the second piezoelectric structure 32 may be the same or different. Optionally, the material of the first piezoelectric structure 24 and the material of the second piezoelectric structure 32 may include polyvinylidene fluoride (PVDF). Furthermore, when the materials of the first piezoelectric structure 24 and the second piezoelectric structure 32 are the same, both may be organic P (VDF-TrFE) copolymers. When the materials of the first piezoelectric structure 24 and the second piezoelectric structure 32 are different, since the ultrasonic transmitting structure 2 needs to transmit ultrasonic waves, its first piezoelectric structure 24 can be made of a material with strong electroacoustic conversion capabilities, such as an organic P (VDF-TrFE-CTE) ternary copolymer; since the ultrasonic receiving structure 3 needs to transmit ultrasonic waves, its second piezoelectric structure 32 can be made of a material with strong acoustic-to-electrical conversion capabilities, such as an organic P (VDF-TrFE) copolymer. Therefore, the performance of the ultrasonic transducer substrate can be enhanced.

[0099] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiments of the present disclosure, as shown in Figures 1 to 6, the ultrasonic emitting structure 2 further includes an etched hole (not shown) communicating with the cavity 21, and the orthographic projection of the first passivation layer 22 on the base substrate 1 does not overlap with the orthographic projection of the etched hole on the base substrate 1. Specifically, the cavity 21 can be manufactured by etching a metal sacrificial layer. First, the metal in the non-cavity portion is etched away, and then filled and leveled with an organic material (such as a resin). The first passivation layer 22 is formed, and the first passivation layer 22 is etched to form an opening corresponding to the etched hole. The metal in the cavity portion is then etched away through the etched hole to form the cavity 21.

[0100] The ultrasonic transducer substrate provided in the embodiment of the present disclosure uses organic PVDF material for its piezoelectric structure, and its cavity is prepared by etching a metal sacrificial layer, thereby enabling the integrated preparation of an ultrasonic transmitting structure, an ultrasonic receiving structure, and a thin film transistor.

[0101] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, as shown in FIG9 and FIG10 , FIG9 and FIG10 are planar schematic diagrams of the cavities 21 in the plurality of ultrasonic transducer units P, and the plurality of ultrasonic transducer units P are distributed in an array on the base substrate 1, that is, the plurality of cavities 21 are distributed in an array on the base substrate 1; wherein,

[0102] As shown in FIG9 , the etching holes V corresponding to the cavities 21 are independently arranged, that is, each cavity 21 is provided with an etching hole V, and the cavities 21 are not associated with each other; or, as shown in FIG10 , the etching holes V corresponding to the cavities 21 in the same column are interconnected, that is, an etching channel H can also be provided on the same column in a column manner to connect the etching holes V in the column.

[0103] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, as shown in Figures 1 to 6 , the orthographic projection shape of the first passivation layer 22 on the base substrate 1 is the same as the orthographic projection shape of the cavity 21 on the base substrate 1. Of course, they can also be different.

[0104] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, the first passivation layer 22 in each ultrasonic emitting structure 2 may be an integral structure, and the first passivation layer 22 of the integral structure only needs to expose the etching hole.

[0105] In specific implementations, in the ultrasonic transducer substrate provided in the embodiments of the present disclosure, as shown in Figures 1-6 , the first passivation layer 22 in each ultrasonic emitting structure 2 can be a mutually independent structure. For example, the ratio of the size of the first passivation layer 22 to the size of the cavity 21 can be greater than or equal to 1.2 and less than or equal to 1.5. In this way, the boundary of the first passivation layer 22 can overlap the resin layer 13 surrounding the cavity 21, preventing the piezoelectric structure and electrodes above from collapsing.

[0106] Alternatively, the cavity 21 may be a circular cavity, and the first passivation layer 22 may be a circular passivation layer. The ratio of the radius of the orthographic projection of the first passivation layer 22 on the base substrate 1 to the radius of the orthographic projection of the cavity 21 on the base substrate 1 is greater than or equal to 1.2 and less than or equal to 1.5. For example, the size ratio may be 1.2, 1.3, 1.4, or 1.5.

[0107] Alternatively, the cavity 21 may be a rectangular cavity, and the first passivation layer 22 may be a rectangular passivation layer, and the ratio of the diagonal of the orthographic projection of the first passivation layer 22 on the base substrate 1 to the diagonal of the orthographic projection of the cavity 21 on the base substrate 1 is greater than or equal to 1.2 and less than or equal to 1.5. For example, the size ratio may be 1.2, 1.3, 1.4, or 1.5.

[0108] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, as shown in FIG1 , the first electrode 23 and the third electrode 31 are provided in the same layer. This allows the third electrode 31 and the first electrode 23 to be formed in a single patterning process simply by changing the original patterning pattern when forming the first electrode 23. This eliminates the need for a separate process for preparing the third electrode 31, simplifying the manufacturing process, reducing production costs, and improving production efficiency.

[0109] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiments of the present disclosure, as shown in Figures 2 and 3, the first electrode 23 and the third electrode 31 can be arranged in different layers, with a second passivation layer 14 disposed between the first electrode 23 and the third electrode 31. This arrangement of the first electrode 23 and the third electrode 31 in different layers can prevent the generation of coupling capacitance between the first electrode 23 and the third electrode 31 when they are arranged in the same layer, which would increase noise and ultimately reduce the signal-to-noise ratio, affecting imaging quality.

[0110] Optionally, as shown in FIG. 2 , the first electrode 23 is disposed close to the base substrate 1 ; as shown in FIG. 3 , the third electrode 31 is disposed close to the base substrate 1 .

[0111] In specific implementations, in the ultrasonic transducer substrate provided in the embodiments of the present disclosure, as shown in Figures 1-3, the second electrode 25 and the fourth electrode 33 can be an integral structure provided on the entire surface, and the first piezoelectric structure 24 and the second piezoelectric structure 32 can be an integral structure provided on the entire surface. In this way, the first electrode 23 and the third electrode 31 share a ground electrode provided on the entire surface (the second electrode 25 and the fourth electrode 33 of the integral structure), and the ultrasonic transmitting structure 2 and the ultrasonic receiving structure 3 share a piezoelectric layer, which can simplify the manufacturing process.

[0112] In a specific implementation, in the ultrasonic transducer substrate provided in the embodiment of the present disclosure, as shown in FIG4 to FIG6 , the second electrode 25 and the fourth electrode 33 may also be arranged at intervals, and the orthographic projection of the fourth electrode 33 on the base substrate 1 surrounds the orthographic projection of the second electrode 25 on the base substrate 1;

[0113] The first piezoelectric structure 24 and the second piezoelectric structure 32 may also be spaced apart, with the orthographic projection of the second piezoelectric structure 32 on the base substrate 1 surrounding the orthographic projection of the first piezoelectric structure 24 on the base substrate 1. In this way, the piezoelectric structures and ground electrodes of the ultrasonic transmitting structure 2 and the ultrasonic receiving structure 3 are patterned and arranged corresponding to the first electrode 23 and the third electrode 31, respectively. This prevents the piezoelectric structures of the ultrasonic transmitting structure 2 and the ultrasonic receiving structure 3 from interfering with each other, thereby reducing noise in the signal received by the ultrasonic receiving structure 3 and improving imaging quality.

[0114] It should be noted that, Figure 4 is based on Figure 1, with the second electrode 25 and the fourth electrode 33 spaced apart, and the first piezoelectric structure 24 and the second piezoelectric structure 32 spaced apart; Figure 5 is based on Figure 2, with the second electrode 25 and the fourth electrode 33 spaced apart, and the first piezoelectric structure 24 and the second piezoelectric structure 32 spaced apart; Figure 6 is based on Figure 3, with the second electrode 25 and the fourth electrode 33 spaced apart, and the first piezoelectric structure 24 and the second piezoelectric structure 32 spaced apart.

[0115] In a specific implementation, the ultrasonic transducer substrate provided in the embodiments of the present disclosure, as shown in Figures 1 and 4, further includes: a third passivation layer 15 disposed entirely between the first electrode 23, the third electrode 31, and the first piezoelectric structure 24; and an organic layer 16 disposed entirely between the first electrode 23, the third electrode 31, and the first passivation layer 22. Specifically, the provision of the third passivation layer 15 can protect the first electrode 23 and the third electrode 31 from corrosion during the fabrication of the first piezoelectric structure 24. The material of the organic layer 16 can be PI, so that when the first piezoelectric structure 24 vibrates, it can drive the first passivation layer 22 and the organic layer 16 to vibrate together.

[0116] In a specific implementation, the ultrasonic transducer substrate provided in the embodiments of the present disclosure, as shown in Figures 2 and 5, further includes: a third passivation layer 15 disposed entirely between the third electrode 31 and the first piezoelectric structure 24, and an organic layer 16 disposed entirely between the first electrode 23 and the first passivation layer 22. Specifically, the provision of the third passivation layer 15 can protect the third electrode 31 from corrosion during the fabrication of the first piezoelectric structure 24. The material of the organic layer 16 can be PI, so that when the first piezoelectric structure 24 vibrates, it can drive the first passivation layer 22 and the organic layer 16 to vibrate together.

[0117] In a specific implementation, the ultrasonic transducer substrate provided in the embodiments of the present disclosure, as shown in Figures 3 and 6, further includes: a third passivation layer 15 disposed entirely between the first electrode 23 and the first piezoelectric structure 24, and an organic layer 16 disposed entirely between the third electrode 31 and the first passivation layer 22. Specifically, the provision of the third passivation layer 15 can protect the first electrode 23 from corrosion during the fabrication of the first piezoelectric structure 24. The material of the organic layer 16 can be PI, so that when the first piezoelectric structure 24 vibrates, it can drive the first passivation layer 22 and the organic layer 16 to vibrate together.

[0118] Optionally, the materials of the first passivation layer 22 , the second passivation layer 14 , the third passivation layer 15 , and the fourth passivation layer 12 may all be silicon nitride, silicon oxide, silicon oxynitride, or the like.

[0119] Specifically, as shown in Figure 11, Figure 11 illustrates the ultrasonic imaging principle of the ultrasonic transducer substrate provided by the embodiment of the present disclosure by taking the structure shown in Figure 1 as an example: in the transmitting stage, a certain driving voltage is given to the first electrode 23 to form a potential difference with the second electrode 25, driving the first piezoelectric structure 24 to vibrate and transmit an ultrasonic signal. After the ultrasonic signal is reflected by the target object 100 (such as the valleys and ridges of the finger), in the receiving stage, the ultrasonic signal returns to the second piezoelectric structure 32 and converts the vibration signal into an electrical signal. The electrical signal is detected by the third electrode 31 and the fourth electrode 33 and transmitted to the driving circuit 4 to form a current to be read, and finally processed by the external IC to form an image.

[0120] Optionally, the ultrasonic transducer substrate provided in the embodiment of the present disclosure can be applied to portable electronic devices such as mobile phones for fingerprint detection, and can also be applied to medical ultrasonic detection equipment for medical detection, such as B-ultrasound, color photography detection, etc.

[0121] Based on the same inventive concept, the present disclosure also provides a method for manufacturing an ultrasonic transducer substrate, which is used to manufacture the ultrasonic transducer substrate provided in the present disclosure. As shown in FIG12 , the manufacturing method includes:

[0122] S1201, providing a substrate;

[0123] S1202, forming a plurality of ultrasonic transducer units on one side of the substrate;

[0124] As shown in FIG13 , forming an ultrasonic transducer unit includes:

[0125] S1301, forming a driving circuit on one side of the base substrate;

[0126] S1302. An ultrasonic transmitting structure and an ultrasonic receiving structure are formed on a side of the driving circuit facing away from the base substrate. The driving circuit is electrically connected to the ultrasonic receiving structure, and the orthographic projection of the ultrasonic receiving structure on the base substrate surrounds the orthographic projection of the ultrasonic transmitting structure on the base substrate. The ultrasonic transmitting structure is configured to convert a received electrical signal into an ultrasonic signal, the ultrasonic receiving structure is configured to convert a received ultrasonic signal into an electrical signal and then output it, and the driving circuit is configured to receive the electrical signal output by the ultrasonic receiving structure.

[0127] The method for manufacturing the above-mentioned ultrasonic transducer substrate provided in the embodiment of the present disclosure, by manufacturing mutually independent ultrasonic transmitting structures and receiving ultrasonic waves, can carry out targeted design of the materials and structures of the ultrasonic transmitting structure and the ultrasonic receiving structure compared to the structure of integrated transmitting and receiving in the related art, thereby facilitating the improvement of the working performance of the ultrasonic transmitting structure and the ultrasonic receiving structure; and, the ultrasonic receiving structure manufactured in the present disclosure surrounds the ultrasonic transmitting structure, which can avoid the reflected ultrasonic signal from causing crosstalk between the ultrasonic receiving structures, reduce the signal noise, and improve the signal-to-noise ratio, thereby improving the imaging quality and clarity.

[0128] The following describes the method for manufacturing the ultrasonic transducer substrate provided by the embodiment of the present disclosure, taking the structure shown in FIG1 as an example. The method specifically includes the following steps:

[0129] (1) As shown in FIG14A , a buffer layer 7 is formed on a base substrate 1, a barrier layer 8 is formed on a side of the buffer layer 7 facing away from the base substrate 1, an active layer Act is formed on a side of the barrier layer 8 facing away from the base substrate 1, a gate insulating layer 9 is formed on a side of the active layer Act facing away from the base substrate 1, the gate insulating layer 9 has vias corresponding to the drain D and the source S, respectively, a gate G is formed on a side of the gate insulating layer 9 facing away from the base substrate 1, an interlayer insulating layer 10 is formed on a side of the gate G facing away from the base substrate 1, the interlayer insulating layer 10 has vias corresponding to the drain D and the source S, respectively, and a drain D and a source S are formed on a side of the interlayer insulating layer 10 facing away from the base substrate 1, wherein the drain D and the source S are electrically connected to the active layer Act through the vias in the gate insulating layer 9 and the interlayer insulating layer 10, respectively.

[0130] (2) As shown in FIG14B , a flat layer 11 is formed on the side of the drain D and the source S facing away from the base substrate 1, and the flat layer 11 has a via hole at a position corresponding to the source S. A second strapping electrode 6 is formed on the side of the flat layer 11 facing away from the base substrate 1, and a fourth passivation layer 12 is formed on the side of the second strapping electrode 6 facing away from the base substrate 1, and the fourth passivation layer 12 has a via hole at a position corresponding to the second strapping electrode 6.

[0131] (3) As shown in FIG14C , a metal film 21 ′ is formed on the side of the fourth passivation layer 12 facing away from the substrate 1 . The metal film 21 ′ includes a cavity region, a non-cavity region, and an etched hole region. The etched hole region is connected to the cavity region. The non-cavity region is etched to remove the metal in the non-cavity region, thereby retaining the metal in the cavity region and the etched hole region. The metal in the region of the metal film 21 ′ corresponding to the first electrode bonding 5 and the second bonding electrode 6 is also retained.

[0132] (4) As shown in FIG. 14D , the non-cavity area where the metal is removed is filled with a resin layer 13 .

[0133] (5) As shown in FIG14E , a first passivation layer 22 is formed on the side of the cavity region facing away from the base substrate 1, and the first passivation layer 22 is etched so that the orthographic projection of the first passivation layer 22 on the base substrate 1 covers the orthographic projection of the cavity region on the base substrate 1, and the orthographic projection of the first passivation layer 22 on the base substrate 1 does not overlap with the orthographic projection of the etched hole region on the base substrate 1.

[0134] (6) As shown in FIG. 14F , an etching solution is injected into the etched hole area to etch the cavity area to remove the metal in the cavity area, thereby forming a cavity 21 and forming a first bonding electrode 5 on the same layer as the cavity 21 .

[0135] (7) As shown in FIG. 14G , an organic layer 16 is formed on the side of the first passivation layer 22 facing away from the base substrate 1 . The organic layer 16 has a via hole at a position corresponding to the first bonding electrode 5 .

[0136] (8) As shown in FIG14H , a first electrode 23 and a third electrode 31 are formed on the same layer and in the form of concentric rings on the side of the organic layer 16 facing away from the base substrate 1 . The first electrode 23 corresponds to the cavity 21 .

[0137] (9) As shown in FIG14I , a third passivation layer 15 is formed on the side of the first electrode 23 and the third electrode 31 facing away from the substrate 1, a first piezoelectric structure 24 and a second piezoelectric structure 32 are formed on the side of the third passivation layer 15 facing away from the substrate 1, and a second electrode 25 and a fourth electrode 33 are formed on the side of the first piezoelectric structure 24 facing away from the substrate 1.

[0138] Therefore, the ultrasonic transducer substrate shown in FIG1 provided by the embodiment of the present disclosure is formed through the steps (1) to (9).

[0139] It should be noted that the manufacturing method of the ultrasonic transducer substrate shown in Figures 2 to 6 is basically the same as the manufacturing method shown in Figure 1, with the difference that the first electrode 23 and the third electrode 31 are arranged in different layers, the first piezoelectric structure 24 and the second piezoelectric structure 32 are independent structures, and the second electrode 25 and the fourth electrode 33 are independent structures.

[0140] Based on the same inventive concept, an embodiment of the present disclosure further provides a device, including the above-mentioned ultrasonic transducer substrate provided by an embodiment of the present disclosure.

[0141] Alternatively, the device may be a display device, i.e., the display device may include the ultrasonic transducer substrate of any of the aforementioned embodiments. This ultrasonic transducer substrate may be positioned within the fingerprint detection area of ​​the display device, thereby enabling functions such as fingerprint unlocking on the display device. Because the ridges and valleys on the surface of a finger reflect ultrasonic signals with varying intensities, the ultrasonic energy reflected by the ridges and valleys of the finger differs. By converting this energy difference into a difference in electrical signals, the ridges and valleys of the fingerprint can be imaged, enabling fingerprint recognition.

[0142] Optionally, the device may also be a device used in medical ultrasound detection equipment for medical detection, such as B-ultrasound, color photography detection equipment, etc.

[0143] Since the principle of solving the problem of this device is similar to that of the aforementioned ultrasonic transducer substrate, the implementation of this device can refer to the implementation of the aforementioned ultrasonic transducer substrate, and the repeated parts will not be repeated.

[0144] The embodiments of the present disclosure provide an ultrasonic transducer substrate and a manufacturing method and device thereof. The ultrasonic transmitting structure can transmit ultrasonic waves, and the ultrasonic receiving structure can receive ultrasonic waves. Compared with the structure in which transmission and reception are integrated in the related art, the structure in which transmission and reception are separately arranged in the present disclosure can be independently controlled. In this way, the materials and structures of the ultrasonic transmitting structure and the ultrasonic receiving structure can be designed in a targeted manner, thereby facilitating the improvement of the working performance of the ultrasonic transmitting structure and the ultrasonic receiving structure. In addition, the present disclosure uses an ultrasonic receiving structure to surround the ultrasonic transmitting structure, which can avoid the reflected ultrasonic signal from causing crosstalk between the ultrasonic receiving structures, reducing the noise of the signal, and improving the signal-to-noise ratio, thereby improving the imaging quality and clarity.

[0145] Although the preferred embodiments of the present disclosure have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present disclosure.

[0146] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present disclosure without departing from the spirit and scope of the embodiments of the present disclosure. Thus, if such changes and modifications of the embodiments of the present disclosure fall within the scope of the claims of the present disclosure and their equivalents, the present disclosure is intended to include such changes and modifications.

Claims

1. An ultrasonic transducer substrate, wherein: It includes a substrate and a plurality of ultrasonic transducer units arranged on the substrate, wherein the ultrasonic transducer units include: an ultrasonic transmitting structure, wherein the ultrasonic transmitting structure is configured to convert a received electrical signal into an ultrasonic signal; An ultrasonic receiving structure, the orthographic projection of the ultrasonic receiving structure on the substrate surrounds the orthographic projection of the ultrasonic transmitting structure on the substrate, and the ultrasonic receiving structure is configured to convert the received ultrasonic signal into an electrical signal and then output it; A driving circuit is arranged between the base substrate and the ultrasonic receiving structure, and the driving circuit is electrically connected to the ultrasonic receiving structure, and the driving circuit is configured to receive an electrical signal output by the ultrasonic receiving structure.

2. The ultrasonic transducer substrate according to claim 1, wherein: The ultrasonic transmitting structure comprises: A cavity is disposed close to the substrate; A first passivation layer is disposed on a side of the cavity away from the base substrate, wherein an orthographic projection of the first passivation layer on the base substrate covers an orthographic projection of the cavity on the base substrate; A first electrode is disposed on a side of the first passivation layer away from the substrate, and the first electrode is configured to receive a driving voltage; A first piezoelectric structure is arranged on a side of the first electrode away from the substrate; The second electrode is arranged on a side of the first piezoelectric structure away from the base substrate, and the second electrode is grounded.

3. The ultrasonic transducer substrate according to claim 2, wherein: The ultrasonic transmitting structure further includes an etched hole communicating with the cavity, and an orthographic projection of the first passivation layer on the substrate does not overlap with an orthographic projection of the etched hole on the substrate.

4. The ultrasonic transducer substrate according to claim 3, wherein: The orthographic projection shape of the first passivation layer on the base substrate is the same as the orthographic projection shape of the cavity on the base substrate.

5. The ultrasonic transducer substrate according to claim 4, wherein: A ratio of a size of the first passivation layer to a size of the cavity is greater than or equal to 1.2 and less than or equal to 1.

5.

6. The ultrasonic transducer substrate according to any one of claims 3 to 5, wherein: The plurality of ultrasonic transducer units are distributed in an array on the substrate; wherein, The etching holes corresponding to the cavities are independently arranged, or the etching holes corresponding to the cavities in the same row are connected to each other.

7. The ultrasonic transducer substrate according to any one of claims 2 to 6, wherein: The orthographic projection shape of the first electrode on the base substrate includes a circle or a square.

8. The ultrasonic transducer substrate according to any one of claims 2 to 7, wherein: The ultrasonic receiving structure comprises: a third electrode, the third electrode being spaced apart from the first electrode, the third electrode and the first electrode being located on the same side of the cavity, and an orthographic projection of the third electrode on the substrate surrounding an orthographic projection of the first electrode on the substrate, and the third electrode being electrically connected to the driving circuit; A second piezoelectric structure is arranged on a side of the third electrode away from the substrate; A fourth electrode is disposed on a side of the second piezoelectric structure away from the substrate, and the fourth electrode is grounded.

9. The ultrasonic transducer substrate according to claim 8, wherein: The first electrode and the third electrode are arranged in the same layer.

10. The ultrasonic transducer substrate according to claim 8, wherein: The first electrode and the third electrode are arranged in different layers, and a second passivation layer is arranged between the first electrode and the third electrode.

11. The ultrasonic transducer substrate according to claim 10, wherein: The first electrode is disposed close to the base substrate, or the third electrode is disposed close to the base substrate.

12. The ultrasonic transducer substrate according to any one of claims 9 to 11, wherein: The second electrode and the fourth electrode are an integrated structure disposed on the entire surface, and the first piezoelectric structure and the second piezoelectric structure are an integrated structure disposed on the entire surface.

13. The ultrasonic transducer substrate according to any one of claims 9 to 11, wherein: The second electrode and the fourth electrode are arranged at intervals, and the orthographic projection of the fourth electrode on the base substrate surrounds the orthographic projection of the second electrode on the base substrate; The first piezoelectric structure and the second piezoelectric structure are spaced apart, and an orthographic projection of the second piezoelectric structure on the base substrate surrounds an orthographic projection of the first piezoelectric structure on the base substrate.

14. The ultrasonic transducer substrate according to any one of claims 9 to 13, wherein: Also includes: A third passivation layer is disposed entirely between the first electrode and / or the third electrode and the first piezoelectric structure, and an organic layer is disposed entirely between the first electrode and / or the third electrode and the first passivation layer.

15. The ultrasonic transducer substrate according to claim 14, wherein: It also includes a first bonding electrode which is in the same layer as the cavity and is spaced apart from the cavity, the third electrode is electrically connected to the first bonding electrode, and the first bonding electrode is electrically connected to the driving circuit; wherein, The cavity and the periphery of the first bonding electrode are filled with a resin layer.

16. The ultrasonic transducer substrate according to any one of claims 2 to 15, wherein: The material of the first piezoelectric structure and the material of the second piezoelectric structure include polyvinylidene fluoride.

17. A device, wherein: It comprises the ultrasonic transducer substrate as described in any one of claims 1 to 16.

18. A method for manufacturing an ultrasonic transducer substrate, used for manufacturing the ultrasonic transducer substrate according to any one of claims 1 to 16, wherein: The production method comprises: providing a substrate base plate; forming a plurality of ultrasonic transducer units on one side of the substrate; The ultrasonic transducer unit comprises: forming a driving circuit on one side of the base substrate; An ultrasonic transmitting structure and an ultrasonic receiving structure are formed on the side of the driving circuit away from the base substrate, the driving circuit is electrically connected to the ultrasonic receiving structure, and the orthographic projection of the ultrasonic receiving structure on the base substrate surrounds the orthographic projection of the ultrasonic transmitting structure on the base substrate; wherein the ultrasonic transmitting structure is configured to convert the received electrical signal into an ultrasonic signal, the ultrasonic receiving structure is configured to convert the received ultrasonic signal into an electrical signal and then output it, and the driving circuit is configured to receive the electrical signal output by the ultrasonic receiving structure.

19. The method of claim 18, wherein: The ultrasonic transmitting structure comprises a cavity, a first passivation layer, a first electrode, a first piezoelectric structure and a second electrode which are stacked in sequence; wherein the cavity is formed by: Forming a metal film on a side away from the substrate, the metal film comprising a cavity area, a non-cavity area and an etched hole area, the etched hole area being connected to the cavity area; Etching the non-cavity area to remove metal from the non-cavity area; Filling a resin layer in the non-cavity area where the metal is removed; forming the first passivation layer on a side of the cavity region away from the base substrate, and etching the first passivation layer so that the orthographic projection of the first passivation layer on the base substrate covers the orthographic projection of the cavity region on the base substrate, and the orthographic projection of the first passivation layer on the base substrate does not overlap with the orthographic projection of the etched hole region on the base substrate; An etching solution is injected into the etching hole area, and the cavity area is etched to remove the metal in the cavity area to form the cavity.

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