Ultrasonic transducer and display panel

Abstract

The invention provides an ultrasonic transducer and a display panel. The ultrasonic transducer comprises a driving backboard (100) and a transduction unit (200). And the transduction unit (200) is positioned on the driving back plate (100). The transduction unit (200) comprises a first electrode (210) located on the driving backboard (100) and electrically connected with the driving backboard (100), a second electrode (220) located on the side, away from the driving backboard (100), of the first electrode (210), a plurality of vibration cavities (230) located between the first electrode (210) and the second electrode (220) and arranged at intervals, and a vibrating diaphragm (240) located between the vibration cavities (230) and the second electrode (220). The ultrasonic transducer can reduce the influence of process deviation on the use performance of the ultrasonic transducer.

Description

Ultrasonic transducer and display panel Technical Field

[0001] The present disclosure relates to the field of sensing technology, and in particular to an ultrasonic transducer and a display panel. Background Art

[0002] Fingerprint recognition technology is widely used in mobile devices such as mobile phones and tablets, as well as in security systems such as access control systems and safes. Currently, fingerprint acquisition is primarily accomplished through optical, capacitive, and ultrasonic imaging methods. Ultrasonic fingerprint recognition technology, in particular, features 3D fingerprint acquisition and eliminates the need for the user's finger to touch the fingerprint acquisition device, improving recognition security and user experience.

[0003] Existing ultrasonic fingerprint recognition technology typically utilizes bulk piezoelectric ultrasonic transducers. Traditional bulk piezoelectric materials utilize piezoelectric ceramics, which are complex to process, require high temperatures, and are difficult to fabricate into precise arrays. Therefore, achieving micron-level fingerprint recognition requires the use of thin-film piezoelectric materials. However, these materials significantly reduce piezoelectric performance, which in turn limits the transceiver's transceiver performance.

[0004] Compared to bulk piezoelectric ultrasonic transducers, micromachined ultrasonic transducers (MUTs) are becoming a development trend due to their simpler manufacturing process and excellent transceiver performance. Micromachined ultrasonic transducers include piezoelectric micromachined ultrasonic transducers (PMUTs) and capacitive micromachined ultrasonic transducers (CMUTs). CMUTs do not require the use of piezoelectric materials and can be manufactured using conventional semiconductor manufacturing processes and materials, which helps control production costs.

[0005] Currently, CMUTs are typically fabricated using silicon-based processes, making it difficult to manufacture large-area devices. Fabricating CMUTs using glass or PI (Polyimide) substrates is beneficial for achieving large-area devices, but the process accuracy is low, which can easily lead to device performance degradation.

[0006] Summary of the Invention

[0007] The present disclosure provides an ultrasonic transducer and a display panel, which are used to improve the performance of the ultrasonic transducer.

[0008] In a first aspect of the present disclosure, an ultrasonic transducer is provided, comprising:

[0009] Driver backplane;

[0010] Multiple transducer units are located on the driving backplate; each transducer unit includes a first electrode located on the driving backplate and electrically connected to the driving backplate, a second electrode located on the side of the first electrode away from the driving backplate, a plurality of vibration cavities spaced apart between the first electrode and the second electrode, and a vibration membrane located between the vibration cavity and the second electrode.

[0011] In the ultrasonic transducer provided by the present disclosure, within the transducer unit, at least some of the multiple vibration cavities have different sizes.

[0012] In the ultrasonic transducer provided by the present disclosure, the multiple vibration cavities include at least one first vibration cavity, at least one second vibration cavity and at least one third vibration cavity; the size of the first vibration cavity is larger than that of the second vibration cavity, and the size of the second vibration cavity is larger than that of the third vibration cavity.

[0013] In the ultrasonic transducer provided by the present disclosure, any two cavities in the first and third cavities are arranged in pairs on both sides of the second cavities.

[0014] In the ultrasonic transducer provided by the present disclosure, within the transducer unit, a plurality of vibration cavities are arranged into an array of three rows and three columns; at least the vibration cavity located in the middle position of the array is the second vibration cavity.

[0015] In the ultrasonic transducer provided by the present disclosure, the difference between the size of the second vibration cavity and the size of the first vibration cavity is less than or equal to 0.6 μm; the difference between the size of the third vibration cavity and the size of the second vibration cavity is less than or equal to 0.6 μm.

[0016] In the ultrasonic transducer provided by the present disclosure, the vibration cavities are arranged into multiple rows within the transducer unit, and the vibration cavities located in two adjacent rows are staggered.

[0017] In the ultrasonic transducer provided by the present disclosure, within the transducer unit, the multiple vibration cavities have the same size and are arranged in an array.

[0018] In the ultrasonic transducer provided by the present disclosure, within the transducer unit, multiple vibration cavities have the same size, and the vibration cavities are arranged in multiple rows, and the vibration cavities located in two adjacent rows are staggered.

[0019] In the ultrasonic transducer provided by the present disclosure, the distance between two adjacent vibration cavities located in the same transducer unit is smaller than the distance between the vibration cavities located in two adjacent transducer units.

[0020] In the ultrasonic transducer provided by the present disclosure, the second electrode includes a plurality of second electrode sub-sections arranged at intervals; the second electrode sub-sections are electrically connected to each other through a first connecting line; one second electrode sub-section corresponds to one vibration cavity; and the orthographic projection of the second electrode sub-section on the driving backplane is located within the orthographic projection of the corresponding vibration cavity on the driving backplane.

[0021] In the ultrasonic transducer provided by the present disclosure, the second electrode includes multiple connection areas; the second electrode sub-sections located in the same connection area are electrically connected to each other, and the second connection sub-sections located in different connection areas are insulated from each other; the second electrode sub-sections located in the same connection area are electrically connected to the same first signal line, for applying the same signal to the second electrode sub-sections within the connection area.

[0022] In the ultrasonic transducer provided by the present disclosure, the first electrode is disposed on the entire surface of the transducer unit.

[0023] In the ultrasonic transducer provided by the present disclosure, the first electrode includes a plurality of first electrode sub-sections arranged at intervals; one first electrode sub-section corresponds to one vibration cavity; the orthographic projection of the vibration cavity on the driving backplane is located within the orthographic projection of the corresponding first electrode sub-section on the driving backplane; wherein each first electrode sub-section of the first electrode is connected to the same second signal line for applying the same signal.

[0024] In the ultrasonic transducer provided by the present disclosure, the second electrode sub-parts are electrically connected via the second connecting wire; and the extension direction of the first connecting wire and the extension direction of the second connecting wire intersect with each other.

[0025] In the ultrasonic transducer provided by the present disclosure, within the transducer unit, multiple vibration cavities are arranged into multiple rows and columns; the first connecting line connects the second electrode sub-sections located in the same row along the row direction of the multiple vibration cavities; the second connecting line connects the first electrode sub-sections located in the same column along the column direction of the multiple vibration cavities.

[0026] In the ultrasonic transducer provided by the present disclosure, multiple vibration cavities are arranged in multiple rows and columns within the transducer unit;

[0027] The first connecting line connects the second electrode sub-sections located in the same row along the row direction of the multiple cavities, and connects the second electrode sub-sections located in the same column along the column direction of the multiple cavities; the second connecting line connects the first electrode sub-sections arranged parallel to the diagonal direction along the diagonal direction of the multiple cavities;

[0028] In the ultrasonic transducer provided by the present disclosure, multiple vibration cavities are arranged in multiple rows and columns within the transducer unit;

[0029] The first connecting line connects the second electrode sub-sections arranged parallel to the diagonal direction of multiple vibration cavities along the diagonal direction of multiple vibration cavities; the second connecting line connects the first electrode sub-sections located in the same row along the row direction of multiple vibration cavities, and connects the first electrode sub-sections located in the same column along the column direction of multiple vibration cavities.

[0030] In the ultrasonic transducer provided by the present disclosure, the driving backplane includes multiple driving circuits; one driving circuit corresponds to one transducer unit, and the driving circuit is electrically connected to the corresponding transducer unit; the driving circuit includes a thin film transistor.

[0031] In the ultrasonic transducer provided by the present disclosure, the driving backplane further includes a substrate; the substrate is located on a side of the driving circuit away from the transducer unit; and the material of the substrate is glass or polyimide.

[0032] According to a second aspect of the present disclosure, a display panel is provided, comprising any one of the above-mentioned ultrasonic transducers.

[0033] According to a third aspect of the present disclosure, a display device is provided, comprising any one of the display panels described above.

[0034] A fourth aspect of the present disclosure provides a method for manufacturing an ultrasonic transducer, the method comprising:

[0035] Making a plurality of first electrodes electrically connected to the driving backplane on the driving backplane;

[0036] A diaphragm and a vibration cavity are formed on a side of the first electrode facing away from the driving back plate; the vibration cavity is located between the diaphragm and the first electrode; and the orthographic projection of the first electrode on the driving back plate overlaps with the orthographic projections of the plurality of vibration cavities on the driving back plate;

[0037] A plurality of second electrodes are made on the side of the diaphragm away from the vibration cavity; one of the second electrodes corresponds to a first electrode; the orthographic projection of the second electrode on the driving backplane overlaps with the orthographic projection of the corresponding first electrode on the driving backplane.

[0038] The beneficial effects of the present disclosure are as follows:

[0039] The present disclosure provides an ultrasonic transducer and display panel. The ultrasonic transducer includes a driving backplate and a transducer unit. The transducer unit is located on the driving backplate. The transducer unit includes a first electrode located on the driving backplate and electrically connected to the driving backplate, a second electrode located on a side of the first electrode facing away from the driving backplate, a plurality of spaced-apart cavities located between the first and second electrodes, and a diaphragm located between the cavities and the second electrodes. In the ultrasonic transducer provided by the present disclosure, a plurality of cavities are spaced-apart between the first and second electrodes of each transducer unit. Accordingly, each transducer unit has a plurality of diaphragms corresponding to the cavities. During the ultrasonic transmission and reception phases, the multiple diaphragms in each transducer unit vibrate together to emit or receive ultrasonic waves. The multiple diaphragms have similar center frequencies and overlap in their -3dB frequency ranges. The superposition of the sound fields can increase the signal intensity and bandwidth. Compared to providing only one cavity in each transducer unit, the impact of process variations on the performance of the ultrasonic transducer can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments of the present disclosure. Obviously, the drawings introduced below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0041] FIG1 is a schematic diagram of a cross-sectional structure of a CMUT according to an embodiment of the present disclosure;

[0042] FIG2 a is a schematic diagram of a driving circuit of a CMUT provided in an embodiment of the present disclosure;

[0043] FIG2 b is a schematic diagram of a driving timing of a CMUT provided in an embodiment of the present disclosure;

[0044] FIG3 is a schematic diagram of a cross-sectional structure of a CMUT in the related art;

[0045] FIG4a is a schematic diagram of a top view of a CMUT according to an embodiment of the present disclosure;

[0046] FIG4 b is a schematic diagram of a top view of a CMUT in the related art;

[0047] FIG5 is a second schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0048] FIG6a is a third schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0049] FIG6 b is a fourth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0050] FIG6c is a fifth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0051] FIG6 d is a sixth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0052] FIG7 a is a seventh schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0053] FIG7 b is an eighth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0054] FIG7 c is a ninth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0055] FIG7 d is a tenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0056] FIG8 is an eleventh schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0057] FIG9 a is a second schematic diagram of a cross-sectional structure of a CMUT provided in an embodiment of the present disclosure;

[0058] FIG9 b is a twelfth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0059] FIG10a is a thirteenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0060] FIG10 b is a fourteenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0061] FIG10c is a fifteenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0062] FIG11a is a third schematic diagram of a cross-sectional structure of a CMUT provided in an embodiment of the present disclosure;

[0063] FIG11 b is a sixteenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0064] FIG12 is a seventeenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0065] FIG13 is an eighteenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure;

[0066] FIG14 is a flow chart of a method for manufacturing an ultrasonic transducer provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0067] In order to make the above-mentioned purposes, features and advantages of the present disclosure more obvious and easy to understand, the present disclosure will be further described below with reference to the accompanying drawings and examples. However, the example embodiments can be implemented in various forms and should not be understood as being limited to the embodiments set forth herein; on the contrary, these embodiments are provided to make the present disclosure more comprehensive and complete, and to fully convey the concepts of the example embodiments to those skilled in the art. The same figure marks in the figures represent the same or similar structures, and their repeated descriptions will be omitted. The words expressing position and direction described in the present disclosure are all explained using the accompanying drawings as examples, but changes can be made as needed, and all changes are included in the scope of protection of the present disclosure. The drawings of the present disclosure are only used to illustrate relative position relationships and do not represent true proportions.

[0068] Fingerprint recognition technology is widely used in mobile devices such as mobile phones and tablets, as well as in security systems such as access control systems and safes. Currently, fingerprint acquisition is primarily accomplished through optical, capacitive, and ultrasonic imaging methods. Ultrasonic fingerprint recognition technology, in particular, features 3D fingerprint acquisition and eliminates the need for the user's finger to touch the fingerprint acquisition device, improving recognition security and user experience.

[0069] Existing ultrasonic fingerprint recognition technology typically utilizes bulk piezoelectric ultrasonic transducers. Traditional bulk piezoelectric materials utilize piezoelectric ceramics, which are complex to process, require high temperatures, and are difficult to fabricate into precise arrays. Therefore, achieving micron-level fingerprint recognition requires the use of thin-film piezoelectric materials. However, these materials significantly reduce piezoelectric performance, which in turn limits the transceiver's transceiver performance.

[0070] Compared to bulk piezoelectric ultrasonic transducers, micromachined ultrasonic transducers (MUTs) are becoming a development trend due to their simpler manufacturing process and excellent transceiver performance. Micromachined ultrasonic transducers include piezoelectric micromachined ultrasonic transducers (PMUTs) and capacitive micromachined ultrasonic transducers (CMUTs). CMUTs do not require the use of piezoelectric materials and can be manufactured using conventional semiconductor manufacturing processes and materials, which helps control production costs.

[0071] Currently, CMUTs are typically manufactured using silicon-based processes, which are difficult to achieve large-area devices. Using glass-based or PI-based (Polyimide) display semiconductor processes to manufacture CMUTs is more conducive to the fabrication of large-area devices.

[0072] FIG1 is a schematic diagram of a cross-sectional structure of a CMUT according to an embodiment of the present disclosure.

[0073] In the embodiment of the present disclosure, as shown in FIG1 , the CMUT includes a driving backplate 100 and a transducer unit 200 .

[0074] The drive backplane 100 is located at the bottom of the CMUT and is used to support and carry the transducer unit 200. The drive backplane 100 is also used to drive the transducer unit 200 to vibrate and transmit ultrasonic waves during the ultrasonic transmission phase, and to receive and collect the current signals converted from the ultrasonic waves during the ultrasonic reception phase. As shown in Figure 1, the drive backplane 100 includes a base substrate 110 and a drive circuit layer 120 located above the base substrate 110.

[0075] The base substrate 110 is used to support and carry the drive circuit layer 120 located thereon. In specific implementations, the base substrate 110 can be made of substrate materials commonly used in display semiconductor processes. For example, in some embodiments, the base substrate 110 can be made of a rigid material, such as glass. In some other embodiments, the base substrate 110 can be made of a flexible material, such as polyimide (PI), although this is not limited here.

[0076] A driving circuit is provided in the driving circuit layer 120, and the transducer unit 200 is electrically connected to the driving circuit to realize ultrasonic transmission and reception control and signal acquisition. In specific implementation, multiple driving circuits can be provided in the driving circuit layer 120, and the CMUT can include multiple transducer units, one driving circuit corresponds to one transducer unit 200, and the transducer unit 200 is electrically connected to the corresponding driving circuit. A driving circuit can include at least one thin film transistor (TFT) T to form a TFT driving circuit. Among them, the TFT driving circuit can be manufactured using low-temperature polysilicon (LTPS) TFT technology, oxide semiconductor TFT technology, or low-temperature polycrystalline oxide (LTPO) technology. The specific manufacturing process of the TFT driving circuit is very mature in the array substrate manufacturing in the display semiconductor field. In specific implementation, reference can be made to the relevant processes for manufacturing array substrates in the display semiconductor process, and will not be described in detail here.

[0077] The transducer unit 200 is located on the driving backplate 100. Specifically, the transducer unit 200 is located on the side of the driving circuit layer 120 facing away from the base substrate 110. As shown in FIG1 , the transducer unit 200 includes a first electrode 210 located on and electrically connected to the driving backplate 100, a second electrode 220 located on the side of the first electrode 210 facing away from the driving backplate 100, a plurality of spaced-apart resonant cavities 230 located between the first electrode 210 and the second electrode 220, and a diaphragm 240 located between the resonant cavities 230 and the second electrode 220. In a specific implementation, the orthographic projection of the second electrode 220 on the driving backplate 100 can be set to be within the orthographic projection of the first electrode 210 on the driving backplate, and the orthographic projection of the plurality of resonant cavities 230 located between the first electrode 210 and the second electrode 220 on the driving backplate 100 can be set to be within the orthographic projection of the first electrode 210 on the driving backplate. The orthographic projection of the diaphragm 240 on the driver backplate 100 completely overlaps with the orthographic projection of the vibration cavity 230 on the driver backplate. The diaphragm 240 can be a single-layer structure or a multi-layer structure, without limitation herein. In a specific implementation, the material of the diaphragm 240 can be at least one of low-temperature polysilicon, silicon nitride (SiN), or silicon oxide (SiO2), without limitation herein.

[0078] During the ultrasonic transmission phase, a DC signal and an AC signal are simultaneously applied between the first electrode 210 and the second electrode 220. This causes the diaphragm 240 located between the first electrode 210 and the second electrode 220 to vibrate as the AC electric field changes, thereby transmitting ultrasonic waves. During the ultrasonic reception phase, only a DC signal is applied between the first electrode 210 and the second electrode 220 to maintain the diaphragm layer 240 in equilibrium. The diaphragm layer 240 vibrates and displaces under the action of ultrasonic waves, thereby changing the capacitance between the first electrode 210 and the second electrode 220, thereby receiving ultrasonic signals.

[0079] In the embodiment of the present invention, the ultrasonic transducer includes at least one transducer unit 200. When the ultrasonic transducer includes multiple transducer units 200, the first electrode 210 of each transducer unit 200 can be disposed in the same membrane layer, the second electrode 220 of each transducer unit 200 can be disposed in the same membrane layer, and the diaphragm 240 of each transducer unit 200 can be disposed in the same membrane layer.

[0080] Specifically, after the drive circuit layer 120 of the driver backplane 100 is fabricated, a flat first layer 130 can be formed on the side of the drive circuit layer 120 facing away from the base substrate 110. The first flat layer 130 protects the drive circuitry of the drive circuit layer 120 and forms a flat surface on the side of the drive circuit layer 120 facing away from the base substrate 110, facilitating the subsequent fabrication of the transducer unit 200. A first conductive layer is then formed on the side of the flat layer 130 facing away from the drive circuit layer 120 through a process such as sputtering deposition. The first conductive layer is then patterned through processes such as exposure, development, and etching to form a plurality of independent and mutually insulated first electrodes 210. Each first electrode 210 can be electrically connected to the drive circuitry in the drive circuit layer 120 via a via extending through the first flat layer 130. After the first electrodes 210 are fabricated, an insulating layer covering the first electrodes 210 is formed on the side of the first electrodes 210 facing away from the driver backplane through a process such as chemical vapor deposition to insulate and protect the first electrodes 210.

[0081] The resonant cavity 230 can be manufactured using a process for etching a sacrificial layer. Specifically, after forming an insulating layer covering the first electrode 210, a metal sacrificial layer can be formed on the side of the insulating layer facing away from the first electrode 210 through a process such as sputtering deposition. The metal sacrificial layer is then patterned through processes such as exposure, development, and etching to form a plurality of mutually spaced metal sacrificial portions, one of which corresponds to one resonant cavity 230, and the orthographic projections of at least two of the metal sacrificial portions on the driving backplane 100 simultaneously fall within the orthographic projection of the same first electrode 210 on the driving backplane 100. After the metal sacrificial part is made, a diaphragm layer is deposited on the entire surface of the side of the metal sacrificial part facing away from the first electrode 210 through processes such as chemical vapor deposition. Then, at the position corresponding to each metal sacrificial part, an opening is opened in the diaphragm layer to penetrate the diaphragm layer and expose the metal sacrificial part. The metal sacrificial part is etched by pouring etching liquid into the opening. A plurality of vibration cavities 230 are formed in the area after the metal sacrificial part is etched, and a diaphragm 240 is formed at the position corresponding to the diaphragm layer and the vibration cavity 230. The vibration cavities 230 are separated from each other by the diaphragm layer located between the vibration cavities 230.

[0082] After the diaphragm 240 and the cavity 230 are fabricated, a second conductive layer is formed on the side of the diaphragm layer facing away from the first driving electrode 210 through processes such as sputtering deposition. The second conductive layer is then patterned through processes such as exposure, development, and etching to form a plurality of independent and insulated second electrodes 220. Each second electrode 220 corresponds to a first electrode 210, and the orthographic projection of the second electrode 220 on the driving backplane 100 is within the orthographic projection of the corresponding first electrode 210 on the driving backplane 100.

[0083] In some embodiments, after the second electrode 220 is formed, an insulating protective layer 300 covering the second electrode 220 can be formed on the side of the second electrode 220 facing away from the diaphragm layer to insulate and protect the second electrode 220. During the operation of the ultrasonic transducer, the second electrode 220 located above the diaphragm 240 and the insulating protective layer 300 located in the overlapping area with the diaphragm 240 can vibrate together with the diaphragm 240, thereby transmitting and receiving ultrasonic waves. In a specific implementation, the insulating protective layer 300 can be a single-layer structure or a multi-layer structure. For example, as shown in Figure 1, the insulating protective layer 300 can include a first insulating layer protective layer 310, a second flat layer 320, and a second insulating layer protective layer 330, wherein the material of the first insulating layer protective layer 310 and the second insulating layer protective layer 330 can include at least one of inorganic insulating materials such as silicon nitride (SiN), silicon oxide (SiO) or silicon oxynitride (SiON), and the second flat layer 320 can be made of an organic insulating material such as resin, which is not limited here.

[0084] It is well known to those skilled in the art that the ultrasonic transducer provided in the embodiments of the present disclosure may also include other structures not mentioned. In specific implementation, the structures not mentioned in the ultrasonic transducer provided in the embodiments of the present disclosure may refer to the prior art and will not be described in detail here.

[0085] FIG2 a is a schematic diagram of a driving circuit of a CMUT according to an embodiment of the present disclosure; FIG2 b is a schematic diagram of a driving timing of a CMUT according to an embodiment of the present disclosure.

[0086] In a specific embodiment, as shown in FIG2a , a driving circuit electrically connected to a transducer unit 200 includes a first transistor T1 , a second transistor T2 , a third transistor T3 , a fourth transistor T4 , and a storage capacitor CB ; wherein,

[0087] The gate of the first transistor T1 is electrically connected to the first gate line G1, the first electrode of the first transistor T1 is electrically connected to the first voltage line Vbias, and the second electrode of the first transistor T1 is electrically connected to the first electrode of the second transistor T2; wherein the first electrode may be the source electrode of the transistor and the second electrode may be the drain electrode of the transistor, or the second electrode may be the source electrode of the transistor and the first electrode may be the drain electrode of the transistor, which will not be repeated in the subsequent content;

[0088] The gate of the second transistor T2 is electrically connected to the second gate line G2, and the second electrode of the second transistor T2 is electrically connected to the gate of the third transistor T3;

[0089] A first electrode of the third transistor T3 is electrically connected to the second voltage line Vdd, and a second electrode of the third transistor T3 is electrically connected to a first electrode of the fourth transistor T4;

[0090] A gate of the fourth transistor T4 is electrically connected to the third gate line G3, and a second electrode of the fourth transistor T4 is electrically connected to the signal read line Vread;

[0091] A first end of the storage capacitor CB is electrically connected to the second voltage line Vdd, and a second end of the storage capacitor CB is electrically connected to the gate of the third transistor T3;

[0092] The first electrode of the transducing unit 200 is electrically connected to the first electrode of the second transistor T2, and the second electrode of the transducing unit 200 is electrically connected to the driving voltage line Vda; wherein Vda is used to input a DC voltage Vdc and an AC voltage Vda to the second electrode.

[0093] Taking fingerprint recognition as an example, referring to Figure 2b, the operation of the ultrasonic transducer can include the following stages:

[0094] In stage t1 (ultrasonic emission stage), both a DC voltage Vdc and an AC voltage Vac are applied to the second electrode of the transducer unit 200, the first transistor T1 and the second transistor T2 are turned on, the first voltage line Vbias is at a constant potential, and the diaphragm 240 of the transducer unit 200 vibrates at a high frequency to emit sound waves.

[0095] In stage t2 (ultrasonic receiving stage), only DC voltage Vdc needs to be applied to the left end of the transducer unit 200, and no AC voltage Vac is required. The first transistor T1 is turned off and the second transistor T2 is turned on. The sound wave is reflected by the finger and reaches the transducer unit 200, driving the diaphragm 240 to vibrate, generating AC current (charge), and storing the charge in the storage capacitor CB.

[0096] In stage t3 (reading stage), the third transistor T3 and the fourth transistor T4 are turned on, and the charge stored in the storage capacitor CB is converted into current through the third transistor T3, and finally output through the fourth transistor T4. The output current is read through the signal read line Vread to realize fingerprint recognition.

[0097] In a specific implementation, after the charge is collected in the t2 stage, the reading in the t3 stage may not be performed directly, that is, there may be a buffer stage t3' between the t2 stage and the t3 stage, and the t3 stage may be performed when reading is needed. In the t3' stage, the voltage on the first voltage line Vbias may be lowered to reduce power consumption.

[0098] It should be noted that the drive circuit and timing diagrams shown in Figures 2a and 2b are merely a specific implementation example provided in the present disclosure to illustrate the operation of the CMUT. The drive circuit in the present disclosure is not limited to the structure shown in Figure 2a. Other circuits that can be combined with the CMUT provided in the present disclosure to implement ultrasonic fingerprint recognition fall within the scope of protection of the present disclosure. Furthermore, the ultrasonic transducer provided in the present disclosure is not limited to fingerprint recognition but can also be used to implement touch control, gesture recognition, medical ultrasonic imaging, underwater detection, and other functions, without limitation herein.

[0099] FIG3 is a schematic diagram of a cross-sectional structure of a CMUT in the related art.

[0100] CMUTs fabricated using display semiconductor processes on glass or PI substrates typically experience process fluctuations of approximately ±2% in planar dimensions and approximately ±10% in thickness. These dimensional fluctuations can cause the resonant frequency of the actual fabricated diaphragm 240 to shift relative to the resonant frequency of the diaphragm 240 of the designed dimensions. Because CMUTs in related art typically employ a global transmission mode to apply a transmission signal to each transducer unit 200, i.e., the voltage signal applied between the first and second electrodes is the same for all transducer units 200 and matches the vibration frequency of the diaphragm 240 of the designed dimensions, diaphragms 240 with actual dimensions that deviate from the designed dimensions operate at mismatched vibration frequencies, weakening the vibration of the diaphragm 240 and causing signal attenuation. In some technical approaches, as shown in FIG3 , only one resonant cavity 230 is provided in a transducer unit 200. If the dimensions of the diaphragm 240 of each transducer unit 200 in the CMUT deviate, signal attenuation can be as high as 90%, seriously impacting the CMUT's performance.

[0101] In the ultrasonic transducer provided by the embodiments of the present disclosure, a plurality of cavities 230 are provided between the first electrode 210 and the second electrode 220 of each transducer unit 200. Accordingly, each transducer unit 200 has a plurality of diaphragms 240 corresponding one-to-one to the cavities 230. During the ultrasonic transmission and reception phases, the multiple diaphragms 240 in each transducer unit 200 vibrate together to emit or receive ultrasonic waves. Compared to providing only one vibration cavity in each transducer unit 200, even though the size of the diaphragms 240 may still have process variations, the increased number of diaphragms 240 can greatly increase the signal intensity and reduce the impact of process variations on the performance of the CMUT.

[0102] FIG4 a is a schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure; FIG4 b is a schematic diagram of a top view of a CMUT in a related art.

[0103] For example, when applied to fingerprint recognition, in order to distinguish the fingerprint valley and ridge signals, the distance between the centers of two adjacent transducer units 200 is usually designed to be less than 80μm, and the maximum cannot exceed 100μm. The single side size of a single vibration cavity 230 is usually 20μm to 30μm. It should be noted that in the embodiment of the present disclosure, the size of the vibration cavity 230 specifically refers to the plane size of the orthographic projection of the vibration cavity 230 on the plane where the driving backplate 100 is located. For example, if the orthographic projection of the vibration cavity 230 on the driving backplate 100 is a circle, the size of the vibration cavity 230 specifically refers to the diameter or radius of the circle. If the orthographic projection of the vibration cavity 230 on the driving backplate 100 is a rectangle, the size of the vibration cavity 230 specifically refers to the length and width of the rectangle. In specific implementation, the orthographic projection of the vibration cavity 230 on the driving backplate 100 can also be other shapes, which are not limited here.

[0104] Taking the pitch Pitch between the centers of two adjacent transducer units 200 as 75 μm and the size R of the cavity 230 (taking a circular cavity as an example, R is the diameter of the cavity; in actual implementation, the cavity may also be of other shapes) as 20 μm as an example, as shown in FIG4a , if the CMUT includes multiple arrayed transducer units 200, and the cavities 230 in the transducer units 200 are also arranged in an array along the direction of the array arrangement of the transducer units 200, then a single transducer unit 200 can be provided with 9 cavities 230 arranged along the row and column directions of the array. Compared with only one cavity 230 in a single transducer unit 200 as shown in FIG4b , nearly 9 times the charge amount can be obtained under ideal conditions. Taking into account the voltage division of the driving circuit, nearly 5 times the charge amount can be obtained. At the same time, considering the signal attenuation of about 30% caused by process deviation, the arrangement shown in FIG4a can actually obtain about 3.5 times the signal amount compared to the arrangement in FIG4b , significantly increasing the signal amount and improving the performance of the CMUT.

[0105] And as the number of diaphragms 240 in a single transducer unit 200 increases, the probability that the diaphragms 240 in a single transducer unit 200 simultaneously have large dimensional deviations, thereby causing the transducer unit 200 to fail, decreases. For example, if the probability of a single diaphragm 240 having a large dimensional deviation is 1 / 10, then the probability of two diaphragms 240 having a large dimensional deviation simultaneously is 1 / 100, and the probability of four diaphragms 240 having a large dimensional deviation simultaneously is 1 / 10000. It can be seen that providing more diaphragms 240 in a single transducer unit 200 can greatly improve process stability and reduce the sensitivity of CMUT performance to the manufacturing process. It should be noted that the above-mentioned probability of a single diaphragm 240 having a large dimensional deviation is only an illustrative illustration of the embodiment of the present disclosure and does not represent a limitation on the actual probability.

[0106] In some embodiments, within the same transducer unit 200 , the multiple vibration cavities 230 have the same size, and the multiple vibration cavities 230 are arranged in an array.

[0107] In some embodiments, within the same transducer unit 200, at least some of the multiple cavities 230 have different sizes. Specifically, when designing an ultrasonic transducer, a single transducer unit 200 can be designed with multiple cavities 230 of different sizes. Without considering process variations, due to the different sizes of the cavities 230, the diaphragms 240 corresponding to each cavity 230 also have different sizes. Diaphragms 240 of different sizes have different resonant frequencies, enabling the ultrasonic transducer to operate at multiple frequencies, thereby increasing the bandwidth of the ultrasonic transducer.

[0108] FIG5 is a second schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure.

[0109] In some embodiments, as shown in FIG5 , within the same transducer unit 200, the multiple cavities 230 may include at least one first cavity 231, at least one second cavity 232, and at least one third cavity 233. The first cavity 231 is larger than the second cavity 232, and the second cavity 232 is larger than the third cavity 233. The first cavity 231 corresponds to the first diaphragm, whose resonant frequency is the first frequency. The second cavity 232 corresponds to the second diaphragm, whose resonant frequency is the second frequency. The third cavity 233 corresponds to the third diaphragm, whose resonant frequency is the third frequency. Without considering process fluctuations, sufficient signal can be obtained through the vibration of the first, second, or third diaphragm alone. Therefore, the CMUT can have three operating frequencies: the first frequency, the second frequency, and the third frequency, greatly expanding the application scenarios of the CMUT. When considering process fluctuations, even if the signal generated by a diaphragm of a certain size is attenuated, it can be compensated by the vibration of the other two diaphragms, thereby meeting the normal operation requirements of the CMUT. For example, when the CMUT operates at the second frequency, even if the vibration of the second diaphragm is weakened due to process deviation, the vibration of the first and third diaphragms can compensate for the signal to a certain extent, ensuring the normal operation of the CMUT.

[0110] In some embodiments, any two of the first and third cavities 231, 233 are arranged in pairs on either side of the second cavity 232. Specifically, as shown in FIG5 , if the same transducer unit 200 includes only one first cavity 231, one second cavity 232, and one third cavity 233, the first cavity 231 and the second cavity 233 can be arranged on either side of the second cavity 232, respectively. If the same transducer unit 200 includes multiple first cavities 231 and multiple third cavities 233, then in a specific implementation, a first cavity 231 and a second cavity 233 can be arranged in pairs on both sides of the second cavity 232 (see Figures 6a, 6b and 6c for details); or two cavities of the same size can be arranged in pairs on both sides of the second cavity 232, for example, two first cavities 231 can be arranged in pairs on both sides of the second cavity 232 or two third cavities can be arranged in pairs on both sides of the second cavity 233 (see Figures 6c and 6d for details), which is not limited here.

[0111] In a specific implementation, the second frequency can be set as the main operating frequency, that is, the ultrasonic transducer transmits and receives ultrasonic waves at the second frequency in most working scenarios and working times. Any two of the first and third cavities 231, 233 are set in pairs on both sides of the second cavity 232. When the ultrasonic transducer operates at the main operating frequency (second frequency), the vibration amplitude of the second diaphragm corresponding to the second cavity 232 is the largest, and the vibration amplitudes of the first diaphragm corresponding to the first cavity 231 and the third diaphragm corresponding to the third cavity 233 located on both sides of the second cavity 232 are relatively small. The intensity of the ultrasonic signal is concentrated at the center of each transducer unit 200, which is beneficial to improving the uniformity and position accuracy of the ultrasonic signals transmitted and received by the ultrasonic transducer at the main operating frequency.

[0112] In a specific implementation, the shape of the orthographic projection of the resonant cavity 230 on the driver backplate 100 can be a regular shape. For example, the shape of the orthographic projection of the resonant cavity 230 on the driver backplate 100 can be a circle, a rectangle, a square, a diamond, etc. In a specific configuration, the centers of the resonant cavities arranged in pairs on both sides of the second resonant cavity 232 can be symmetrical about the center of the second resonant cavity 232 to further improve signal uniformity. For example, a first resonant cavity 231 and a third resonant cavity 233 are arranged in pairs on both sides of a second resonant cavity 232. In a specific configuration, the center of the first resonant cavity 231 and the center of the third resonant cavity 233 can be symmetrical about the center of the second resonant cavity 232. The center of the resonant cavity can specifically be the geometric center of the orthographic projection of the resonant cavity 230 on the driver backplate 100, which is not limited here.

[0113] FIG6a is a third schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure; FIG6b is a fourth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure; FIG6c is a fifth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure; and FIG6d is a sixth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure.

[0114] In a specific implementation, as shown in FIG6a to FIG6d , in a transducer unit 200 , a plurality of vibration cavities 230 are arranged in an array of three rows and three columns. At least the vibration cavity 230 located in the middle of the array is the second vibration cavity 232 .

[0115] In some embodiments, as shown in FIG6a , within a transducer unit 200 , a plurality of resonant cavities 230 are arranged in an array of three rows and three columns. In the first row of the array, the first resonant cavity 231 , the second resonant cavity 232 , and the third resonant cavity 233 are arranged in sequence along the row direction x of the array; in the second row of the array, the first resonant cavity 231 , the second resonant cavity 232 , and the third resonant cavity 233 are arranged in sequence in a direction opposite to that of the first row; in the third row of the array, the first resonant cavity 231 , the second resonant cavity 232 , and the third resonant cavity 233 are arranged in sequence in the same direction as that of the first row.

[0116] In some embodiments, as shown in FIG6b , within a transducer unit 200 , a plurality of vibration cavities 230 are arranged in an array of three rows and three columns. The plurality of vibration cavities 230 in the same row of the array have the same size. In the same column of the array, the first vibration cavity 231 , the second vibration cavity 232 , and the third vibration cavity 233 are arranged sequentially along the column direction of the array.

[0117] In some embodiments, as shown in FIG6c , within a transducer unit 200, a plurality of cavities 230 are arranged in an array of three rows and three columns, wherein the middle position of each row is set as a second cavity 232, and the middle position of each column is set as a second cavity 232. Two first cavities 231 are arranged in pairs at two diagonal corners of the array with respect to the second cavity 232 located in the middle of the array, and two third cavities 233 are arranged in pairs at the remaining two diagonal corners of the array with respect to the second cavity 232 located in the middle of the array; alternatively, one first cavity 231 and one third cavity 233 are arranged in pairs at two diagonal corners of the array with respect to the second cavity 232 located in the middle of the array, and one first cavity 231 and one third cavity 233 are arranged symmetrically at the remaining two diagonal corners of the array with respect to the second cavity 232 located in the middle of the array.

[0118] In some embodiments, as shown in Figure 6d, within a transducer unit 200, multiple vibration cavities 230 are arranged in an array of three rows and three columns, a second vibration cavity 232 is set in the middle position of the array, and the first vibration cavity 231 and the second vibration cavity 233 are arranged around the second vibration cavity 232 at intervals.

[0119] In the embodiments shown in Figures 6a to 6d, x is the row direction of the array and y is the column direction of the array. In other embodiments, x can be the column direction of the array and y can be the row direction of the array, which is not limited here.

[0120] When designing the dimensions of the resonant cavity 230, the sizes of the first, second, and third resonant cavities 231, 232, and 233 can be determined based on the dimensional error range caused by process fluctuations. For example, the error range of the resonant cavity size R caused by process fluctuations in semiconductors is typically ±0.6 μm. Therefore, when designing the dimensions of the resonant cavity 230, the difference between the dimensions of the second resonant cavity 232 and the first resonant cavity 231, and the difference between the dimensions of the third resonant cavity 233 and the second resonant cavity 232, can be less than or equal to 0.6 μm. Specifically, the difference between the size of the second cavity 232 and the size of the first cavity 231, and the difference between the size of the third cavity 233 and the size of the second cavity 232 can be designed to be half of the error caused by process fluctuations. When the error range caused by process fluctuations is ±0.6μm, the difference between the size of the second cavity 232 and the size of the first cavity 231, and the difference between the size of the third cavity 233 and the size of the second cavity 232 can be 0.3μm, so that the size deviation of the first diaphragm and the third diaphragm from the second diaphragm is small, and the center frequency is close, ensuring that the ultrasonic signal transmitted and received by the ultrasonic transducer has a greater signal strength. In specific implementation, by reasonably setting the size and arrangement of the first cavity 231, the second cavity 232, and the third cavity 233, the center frequencies of the vibrations of the first cavity 231, the second cavity 232, and the third cavity 233 are close, and there is overlap within the -3dB frequency range, so that the main peak of the transducer unit can transition smoothly, increasing the bandwidth of the CMUT. In practice, if the cavity bandwidth is too narrow or the process variation is too large, resulting in a lack of -3dB frequency range overlap, this can be compensated for by reducing the size difference between the cavities or increasing their dimensions. For example, when designing the cavity dimensions, the error caused by process variation can be added or subtracted by one-quarter of the second cavity's size to obtain the design dimensions of the first and third cavities, respectively. For example, the transducer unit 200 shown in FIG5 can have a diameter of 20 μm, the first cavity 231 can have a diameter of 19.5 μm, and the third cavity 233 can have a diameter of 20.5 μm, without limitation.

[0121] It should be noted that in the embodiment of the present disclosure, the difference between the size of the second cavity 232 and the size of the first cavity 231, and the difference between the size of the third cavity 233 and the size of the second cavity 232, are all without considering the influence of process fluctuations. In actual implementation, due to the influence of process errors, the difference between the size of the second cavity 232 and the size of the first cavity 231, and the difference between the size of the third cavity 233 and the size of the second cavity 232 may be different from the design value. Taking a circular cavity as an example, the design diameter of the second cavity 232 can be 20μm, the design diameter of the first cavity 231 can be 19.5μm, and the design diameter of the third cavity 232 can be 20.5μm. Taking into account the error of 0.6μm process fluctuation, the difference between the diameter of the second cavity 232 and the diameter of the first cavity 231 in the actual production range is -0.7μm to 1.7μm, and the difference between the diameter of the third cavity 233 and the diameter of the second cavity 232 in the actual production range is 0.7μm to 1.7μm. In specific implementations, the actual size of the difference between the size of the second vibration cavity 232 and the size of the first vibration cavity 231, and the actual size of the difference between the size of the third vibration cavity 233 and the size of the second vibration cavity 232 may vary depending on specific circumstances and are not limited here.

[0122] In some embodiments, within a transducer unit 200, multiple cavities 230 are arranged in multiple rows, with the cavities 230 located in two adjacent rows being staggered. The difference between the arrangement of multiple cavities 230 in a transducer unit 200 in multiple rows and the arrangement of the cavities 230 in an array as shown in Figures 6a to 6d is that in the array arrangement of the multiple cavities 230, the number of columns of cavities 230 is the same as the number of cavities 230 located in the same row, while in the staggered arrangement of the cavities 230 in two adjacent rows, the number of columns of cavities 230 is the sum of the number of cavities 230 in the two adjacent rows. Arranging multiple cavities 230 in multiple rows and staggering the cavities 230 in two adjacent rows facilitates providing a greater number of cavities 230 in a transducer unit 200 of the same size, further increasing signal quality.

[0123] FIG7a is the seventh schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure; FIG7b is the eighth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure; FIG7c is the ninth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure; and FIG7d is the tenth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure.

[0124] For example, in some embodiments, as shown in Figures 7a and 7b, the pitch Pitch between two adjacent transducer units 200 is 50 μm, and the size R of the cavity 230 (using a circular cavity as an example, R is the diameter of the cavity; in actual implementation, the cavity may also have other shapes) is 26 μm. As shown in Figure 7a, when arranged in an array, only one cavity 230 can be provided in the same transducer unit 200; as shown in Figure 7b, when the cavities 230 are arranged in multiple rows, and the cavities 230 in two adjacent rows are staggered, two cavities 230 can be provided in the same transducer unit 200.

[0125] In some embodiments, as shown in Figures 7c and 7d, the pitch Pitch between two adjacent transducer units 200 is 55μm, and the size R of the vibration cavity 230 (taking a circular vibration cavity as an example, R is the diameter of the vibration cavity; in actual implementation, the vibration cavity can also be of other shapes) is 20μm. As shown in Figure 7c, when arranged in an array, only four vibration cavities 230 arranged in two rows and two columns can be set in the same transducer unit 200; as shown in Figure 7d, when the vibration cavities 230 are arranged in multiple rows and the vibration cavities 230 located in two adjacent rows are staggered, the same transducer unit 200 can simultaneously be provided with five vibration cavities 230 arranged in three rows. The first and third rows are respectively provided with two vibration cavities 230, and the second row is provided with one vibration cavity 230. In a specific implementation, the vibration cavity 230 located in the second row of the five vibration cavities 230 can be set as the second vibration cavity, and the first and third vibration cavities can be arranged around the second vibration cavity at intervals, which is not limited here.

[0126] In the embodiment shown in Figures 7a to 7d, x is the row direction of the arrangement of the cavities, and y is the column direction of the arrangement of the cavities. In other embodiments, x can be the column direction of the arrangement of the cavities, and y can be the row direction of the arrangement of the cavities, which is not limited here. In the embodiment shown in Figures 7a to 7d, the dimensions of the cavities 230 in the same transducer unit are the same for illustration. In specific implementation, when the dimensions of the cavities 230 in the same transducer unit are not exactly the same, an arrangement in which the cavities in two adjacent rows are staggered can also be adopted, which is not limited here.

[0127] In some embodiments, the spacing between two adjacent cavities 230 within the same transducer unit 200 is smaller than the spacing between the cavities 230 within two adjacent transducer units 200, thereby maximizing the spacing between the cavities 230 within two adjacent transducer units 200 and preventing crosstalk between the two adjacent transducer units 200. In a specific implementation, the spacing between two cavities 230 can be the distance between the centers of the two cavities 230, or the minimum distance between the edges of the two cavities 230, which is not limited here.

[0128] FIG8 is an eleventh schematic diagram of a top view structure of a CMUT provided in an embodiment of the present disclosure.

[0129] For example, as shown in FIG8 , the center-to-center spacing Pitch between two adjacent transducer units 200 is 80 μm, the size R of the vibration cavity 230 is 20 μm, the center-to-center spacing P1 between two adjacent vibration cavities 230 in the same transducer unit 200 is 30 μm, and the minimum distance P2 between the centers of two vibration cavities 230 located in two adjacent transducer units 200 is 50 μm. In a specific implementation, while ensuring the strength of the diaphragm corresponding to each vibration cavity 230 in the same transducer unit 200, the spacing between two adjacent vibration cavities 230 in the same transducer unit 200 can be minimized, thereby increasing the spacing between the vibration cavities 230 located in two adjacent transducer units 200, thereby avoiding crosstalk between the sound waves of the two adjacent transducer units 200.

[0130] FIG9 a is a second schematic diagram of a cross-sectional structure of a CMUT provided in an embodiment of the present disclosure; FIG9 b is a twelfth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure.

[0131] In some embodiments, as shown in Figures 9a and 9b, the second electrode 220 includes a plurality of second electrode sub-portions 221 that are spaced apart. The spacing specifically refers to the second electrode sub-portions 221 being spaced apart by a certain distance in space, and does not limit the connection relationship between the second electrode sub-portions 221. One second electrode sub-portion 221 corresponds to one vibration cavity 230. The orthographic projection of the second electrode sub-portion 221 on the driving backplate 100 overlaps with the orthographic projection of the corresponding vibration cavity 230 on the driving backplate 100. In a specific implementation, the orthographic projection of the second electrode sub-portion 221 on the driving backplate 100 can be located within the orthographic projection of the corresponding vibration cavity 230 on the driving backplate 100, which is not limited here. The plurality of second electrode sub-portions 221 are electrically connected through a first connecting trace 222. Dividing the second electrode 220 into a plurality of second electrode sub-sections 221 is beneficial to reducing the overlapping area between the second conductive layer where the second electrode 220 is located and the first conductive layer where the first electrode 210 is located, compared to setting the second electrode 220 on the entire surface in a transducer unit 200, reducing the parasitic capacitance generated by unnecessary overlap between the first conductive layer and the second conductive layer, and improving the accuracy of the ultrasonic transducer.

[0132] In some embodiments, as shown in FIG9b , all second electrode sub-segments 221 in the same transducer unit 200 can be connected to the same first signal line 223 via a first connection trace 222, so that the same driving signal can be input to all second electrode sub-segments 221 in the same transducer unit 200 via the first signal line 223 for driving. In a specific implementation, the first signal line 223 includes a driving voltage line Vda.

[0133] FIG10a is the thirteenth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure; FIG10b is the fourteenth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure; and FIG10c is the fifteenth schematic diagram of the top view structure of the CMUT provided in an embodiment of the present disclosure.

[0134] In the embodiment of the present invention, a transducer unit 200 may include multiple resonant cavities 230. As the number of resonant cavities 230 increases and the size of the transducer unit 200 increases, the size differences between the resonant cavities 230 located in different regions within the same transducer unit 200 may increase. For example, as the number of resonant cavities 230 increases, the resonant cavities 230 located in two opposing diagonal regions of the transducer unit 200 may have a larger size difference due to the greater distance between them. Therefore, in a specific implementation, a partitioned power supply method can be used to divide the second electrode 220 of a transducer unit 200 into multiple connection areas. The size differences between the various cavities 230 located in the same connection area due to process fluctuations are relatively small. The second electrode sub-sections 221 in the same connection area are connected via first connection traces 222 and connected to the same first signal line 223 to apply the same voltage signal. The cavities 230 located in different connection areas may have larger size differences due to process fluctuations. In a specific implementation, the second electrode sub-sections 221 located in different connection areas are insulated from each other. The second electrode sub-sections 221 located in different areas are respectively connected to different first signal lines 223 to apply voltage signals that match the size of the cavities 230 in each connection area. This allows the diaphragms 240 located in different connection areas of the same transducer unit 200 to operate at appropriate frequencies, thereby improving the strength of the ultrasonic signal. In a specific implementation, the first signal line 223 includes a drive voltage line Vda.

[0135] In some embodiments, as shown in Figure 10a, the second electrode sub-sections 221 located in the same column can be connected in series through the first connecting line 222, and the second electrode sub-sections 221 in the same column connected in series are connected to the same first signal line 223; the second electrode sub-sections 221 located in different columns are connected to different first signal lines 223.

[0136] In some embodiments, as shown in FIG10b , the same second electrode 220 can be divided into multiple connection regions along a diagonal direction. Specifically, the second electrode 220 can be divided into two opposing connection regions, or as shown in FIG10b , the second electrode 220 can be divided into four opposing connection regions, with the second electrode sub-sections 221 located in the same connection region being connected via first connection traces 222 and connected to the same first signal line 223 , while the second electrode sub-sections 221 located in different connection regions are connected to different first signal lines 223 .

[0137] In some embodiments, as shown in FIG10c , the same second electrode 220 can be divided into multiple connection regions from the inside out. Specifically, the second electrode 220 can be divided into an internal connection region and an external connection region; second electrode sub-sections 221 located in the same connection region are connected via first connection traces 222 and connected to the same first signal line, while second electrode sub-sections 221 located in different connection regions are connected to different first signal lines.

[0138] In the embodiments shown in Figures 10a to 10c, x is the row direction of the arrangement of the cavities, and y is the column direction of the arrangement of the cavities. In other embodiments, x can be the column direction of the arrangement of the cavities, and y can be the row direction of the arrangement of the cavities, which is not limited here.

[0139] In some embodiments, as shown in FIG. 9 b , within a transducer unit 200 , the first electrode 210 is disposed on the entire surface to reduce process difficulty.

[0140] FIG11 a is a third schematic diagram of a cross-sectional structure of a CMUT provided in an embodiment of the present disclosure; FIG11 b is a sixteenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure.

[0141] In some embodiments, as shown in Figures 11a and 11b, the first electrode 210 includes a plurality of first electrode sub-portions 211 that are spaced apart. The spaced apart arrangement specifically refers to the first electrode sub-portions 211 being spaced apart by a certain distance in space, and does not limit the connection relationship between the first electrode sub-portions 211. One first electrode sub-portion 211 corresponds to one vibration cavity 230. The orthographic projection of the first electrode sub-portion 211 on the driving backplate 100 overlaps with the orthographic projection of the corresponding vibration cavity 230 on the driving backplate 100. In a specific implementation, the orthographic projection of the vibration cavity 230 on the driving backplate 100 may be located within the orthographic projection of the corresponding first electrode sub-portion 211 on the driving backplate 100, which is not limited here. Dividing the first electrode 210 into a plurality of first electrode sub-portions 211 is beneficial for reducing the overlapping area between the second conductive layer where the first electrode 210 is located and the first conductive layer where the second electrode 220 is located, reducing the parasitic capacitance generated by the unnecessary overlap between the first conductive layer and the second conductive layer, and improving the accuracy of the ultrasonic transducer.

[0142] In a specific implementation, the multiple first electrode sub-sections 211 in the first electrode 210 are electrically connected via the second connection traces 212. As shown in FIG11b , all first electrode sub-sections 211 in the same transducer unit 200 can be connected to the same second signal line 213 via the second connection traces 212. In a specific implementation, the second signal line 213 can include a first voltage line Vbias and a signal read line Vread.

[0143] In the embodiments shown in Figures 2a-2b, 9a-10c, and 11a-11b, the electrode connection method of the CMUT provided by the present disclosure is described using the second electrode 220 connected to the driving voltage line Vda as an example. In some embodiments, the first electrode 210 can be connected to the driving voltage line Vda, and the first electrode sub-segments 211 in the first electrode 210 can also be connected using the partitioned method shown in Figures 10a-10c, which will not be described in detail here.

[0144] In the ultrasonic transducer provided in the embodiment of the present disclosure, only the first electrode 210 can be provided to include multiple first electrode sub-portions 211, and the second electrode 220 can be provided on the entire surface; or only the second electrode 220 can be provided to include multiple second electrode sub-portions 221, and the first electrode 210 can be provided on the entire surface; or the first electrode 210 can be provided to include multiple first electrode sub-portions 211, and the second electrode 220 can be provided to include multiple second electrode sub-portions 221 at the same time, which is not limited here.

[0145] In some embodiments, the first electrode 210 includes multiple first electrode sub-portions 211, and the second electrode 220 includes multiple second electrode sub-portions 221. The extension direction of the second connecting trace 212 used to connect the first electrode sub-portions 211 intersects with the extension direction of the first connecting trace 222 used to connect the second electrode sub-portions 221, thereby further reducing the overlapping area between the first connecting trace 222 and the second connecting trace 212, and reducing the parasitic capacitance generated between the first connecting trace 222 and the second connecting trace 212.

[0146] FIG12 is a seventeenth schematic diagram of a top view of a CMUT provided in an embodiment of the present disclosure.

[0147] In some embodiments, within a transducer unit 200, a plurality of cavities 230 are arranged into multiple rows and columns. The plurality of cavities 230 are arranged into multiple rows and columns. The plurality of cavities 230 can be arranged into an array as shown in FIG11b, or the cavities 230 located in two adjacent rows are staggered and arranged to form multiple rows and columns as shown in FIG12, which is not limited here. In a specific implementation, the first connecting trace 222 connects the second electrode sub-portions 221 located in the same row along the row direction of the plurality of cavities 230; the second connecting trace 212 connects the first electrode sub-portions 211 located in the same column along the column direction of the plurality of cavities 230, so that the extension direction of the second connecting trace 212 intersects with the extension direction of the first connecting trace 222, thereby reducing the parasitic capacitance generated between the first connecting trace 222 and the second connecting trace 212.

[0148] In the embodiments shown in Figures 11b and 12, x is the row direction of the arrangement of the cavities, and y is the column direction of the arrangement of the cavities. In other embodiments, x can be the column direction of the arrangement of the cavities, and y can be the row direction of the arrangement of the cavities, which is not limited here.

[0149] FIG13 is an eighteenth schematic diagram of a top view structure of a CMUT provided in an embodiment of the present disclosure.

[0150] In some embodiments, within a transducer unit 200, multiple cavities 230 are arranged in multiple rows and columns. The multiple cavities 230 are arranged in multiple rows and columns. The multiple cavities 230 can be arranged in an array as shown in FIG13, or the cavities 230 located in two adjacent rows can be staggered to form multiple rows and columns, which is not limited here. In a specific implementation, taking the arrangement of multiple cavities 230 in an array as an example, as shown in FIG13, the first connecting trace 222 connects the second electrode sub-portions 221 located in the same row along the row direction of the multiple cavities 230, and connects the second electrode sub-portions 221 located in the same column along the column direction of the multiple cavities 230. The second connecting trace 212 connects the first electrode sub-portions 211 arranged parallel to the diagonal direction of the multiple cavities 230, so that the extension direction of the second connecting trace 212 intersects with the extension direction of the first connecting trace 222, thereby reducing the parasitic capacitance generated between the first connecting trace 222 and the second connecting trace 212. Furthermore, connection channels between the second electrode sub-sections 221 and the first electrode sub-sections 211 can be increased, so that the signal applied to each first electrode sub-section 211 and the second electrode sub-section 221 is more uniform.

[0151] In some embodiments, within a transducer unit 200, a plurality of cavities 230 are arranged into multiple rows and columns. The plurality of cavities 230 may be arranged into multiple rows and columns, and the plurality of cavities 230 may be arranged into an array, or the cavities 230 located in two adjacent rows may be staggered and arranged to form multiple rows and columns, which is not limited here. The first connecting trace 222 connects the second electrode sub-sections 221 arranged parallel to the diagonal direction along the diagonal direction of the plurality of cavities 230; the second connecting trace 212 connects the first electrode sub-sections 211 located in the same row along the row direction of the plurality of cavities 230, and connects the first electrode sub-sections 211 located in the same column along the column direction of the plurality of cavities 230. In specific implementation, reference may be made to the connection method in FIG. 13 , which will not be elaborated here.

[0152] In the embodiment shown in Figure 13, x is the row direction of the arrangement of the cavities, and y is the column direction of the arrangement of the cavities. In other embodiments, x can be the column direction of the arrangement of the cavities, and y can be the row direction of the arrangement of the cavities, which is not limited here.

[0153] The present disclosure also provides a display panel, which includes an ultrasonic transducer provided by any of the above embodiments. In specific implementations, the display panel can be a liquid crystal display (LCD) panel, an organic light emitting diode (OLED) display panel, a light emitting diode (LED) display panel, a micro light emitting diode (Micro LED) display panel, etc., which are not limited here. The ultrasonic transducer can be used to implement fingerprint recognition, gesture recognition, touch operation and other functions of the display panel, which are not limited here.

[0154] The display panel provided by the embodiment of the present disclosure has the same or similar technical effects as the ultrasonic transducer provided by any of the above embodiments, and will not be described in detail here.

[0155] The present disclosure also provides a display device comprising the display panel provided in any of the above-described embodiments. The display device may be a mobile phone, a tablet computer, a laptop computer, or the like, without limitation. The display device provided in the present disclosure has the same or similar technical effects as the display panel provided in any of the above-described embodiments, and thus is not further described here.

[0156] FIG14 is a flow chart of a method for manufacturing an ultrasonic transducer provided in an embodiment of the present disclosure.

[0157] The present disclosure also provides a method for manufacturing an ultrasonic transducer, as shown in FIG14 , the method comprising the following steps:

[0158] S141: forming a plurality of first electrodes electrically connected to the driving backplane on the driving backplane;

[0159] S142: Fabricating a diaphragm and a vibration cavity on a side of the first electrode facing away from the driving back plate; wherein the vibration cavity is located between the diaphragm and the first electrode; and an orthographic projection of the first electrode on the driving back plate overlaps with an orthographic projection of the plurality of vibration cavities on the driving back plate;

[0160] S143: A plurality of second electrodes are fabricated on a side of the diaphragm facing away from the vibration cavity; one of the second electrodes corresponds to one of the first electrodes.

[0161] In specific implementation, in the manufacturing method of the ultrasonic transducer provided by the embodiment of the present disclosure, the manufacturing of the driving backplate is completed first, and then a plurality of first electrodes electrically connected to the driving backplate are manufactured on the driving backplate, wherein one of the driving electrodes is used to form a transducer unit. After the first electrode is manufactured, a diaphragm and a vibration cavity are manufactured on the side of the first electrode facing away from the driving backplate. The vibration cavity is located between the diaphragm and the first electrode. The orthographic projection of the first electrode on the driving backplate overlaps with the orthographic projections of the plurality of vibration cavities on the driving backplate. The diaphragm and the vibration cavity can be manufactured by etching a sacrificial layer. The specific method has been described in detail in the above content and will not be repeated here. After the diaphragm and the vibration cavity are formed, a plurality of second electrodes are manufactured on the side of the diaphragm facing away from the vibration cavity. One of the second electrodes corresponds to one of the first electrodes. The orthographic projection of the second electrode on the driving backplate overlaps with the orthographic projection of the corresponding first electrode on the driving backplate. One of the second electrodes, the corresponding first electrode, and the diaphragm and the vibration cavity located between the first and second electrodes form a transducer unit.

[0162] The embodiments of the present disclosure have described the specific structure of the ultrasonic transducer in detail. During specific implementation, the specific manufacturing method of the ultrasonic transducer provided by the embodiments of the present disclosure can refer to the specific structure of the aforementioned ultrasonic transducer and will not be repeated here.

[0163] 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.

[0164] Obviously, those skilled in the art may make various changes and modifications to the present disclosure without departing from the spirit and scope of the present disclosure. Thus, if these modifications and variations 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 these modifications and variations.

Claims

1. An ultrasonic transducer, wherein: include: Driver backplane; A plurality of transducer units are located on the driving back plate; Each of the transducer units includes a first electrode located on the driving back plate and electrically connected to the driving back plate, a second electrode located on a side of the first electrode away from the driving back plate, a plurality of vibration cavities spaced apart between the first electrode and the second electrode, and a vibration membrane located between the vibration cavity and the second electrode.

2. The ultrasonic transducer according to claim 1, wherein: In the transducer unit, at least some of the multiple vibration cavities have different sizes.

3. The ultrasonic transducer according to claim 2, wherein: The multiple vibration cavities include at least one first vibration cavity, at least one second vibration cavity and at least one third vibration cavity; the size of the first vibration cavity is larger than that of the second vibration cavity, and the size of the second vibration cavity is larger than that of the third vibration cavity.

4. The ultrasonic transducer according to claim 3, wherein: Any two of the first vibration cavity and the third vibration cavity are arranged in pairs on both sides of the second vibration cavity.

5. The ultrasonic transducer according to claim 4, wherein: In the transducer unit, the multiple vibration cavities are arranged into an array of three rows and three columns; at least the vibration cavity located in the middle position of the array is the second vibration cavity.

6. The ultrasonic transducer according to any one of claims 3 to 5, wherein: The difference between the size of the second vibration cavity and the size of the first vibration cavity is less than or equal to 0.6 μm; the difference between the size of the third vibration cavity and the size of the second vibration cavity is less than or equal to 0.6 μm.

7. The ultrasonic transducer according to any one of claims 1 to 4, wherein: In the transducer unit, the vibration cavities are arranged into multiple rows, and the vibration cavities located in two adjacent rows are staggered.

8. The ultrasonic transducer according to claim 1, wherein: In the transducer unit, the multiple vibration cavities have the same size and are arranged in an array.

9. The ultrasonic transducer according to claim 1, wherein: In the transducer unit, the multiple vibration cavities have the same size, and the vibration cavities are arranged in multiple rows, and the vibration cavities located in two adjacent rows are staggered.

10. The ultrasonic transducer according to any one of claims 1 to 9, wherein: The distance between two adjacent vibration cavities in the same transducer unit is smaller than the distance between the vibration cavities in two adjacent transducer units.

11. The ultrasonic transducer according to any one of claims 1 to 10, wherein: The second electrode includes a plurality of second electrode sub-sections arranged at intervals; the second electrode sub-sections are electrically connected to each other via a first connecting wire; one second electrode sub-section corresponds to one vibration cavity; the orthographic projection of the second electrode sub-section on the driving backplane is located within the orthographic projection of the corresponding vibration cavity on the driving backplane.

12. The ultrasonic transducer according to claim 11, wherein: The second electrode includes multiple connection areas; the second electrode sub-parts located in the same connection area are electrically connected to each other, and the second connection sub-parts located in different connection areas are insulated from each other; the second electrode sub-parts located in the same connection area are electrically connected to the same first signal line, for applying the same signal to the second electrode sub-parts in the connection area.

13. The ultrasonic transducer according to claim 11 or 12, wherein: In the transducer unit, the first electrode is disposed over the entire surface.

14. The ultrasonic transducer according to claim 11 or 12, wherein: The first electrode comprises a plurality of first electrode sub-parts arranged at intervals; one of the first electrode sub-parts corresponds to one of the vibration cavities; the orthographic projection of the vibration cavity on the driving backplane is located within the orthographic projection of the corresponding first electrode sub-part on the driving backplane; The first electrode sub-portions of the first electrode are connected to the same second signal line to apply the same signal.

15. The ultrasonic transducer according to claim 14, wherein: The second electrode sub-parts are electrically connected to each other through a second connecting wire; and an extending direction of the first connecting wire and an extending direction of the second connecting wire intersect each other.

16. The ultrasonic transducer according to claim 15, wherein: In the transducer unit, the multiple vibration cavities are arranged into multiple rows and columns; the first connecting line connects the second electrode sub-sections located in the same row along the row direction of the multiple vibration cavities; the second connecting line connects the first electrode sub-sections located in the same column along the column direction of the multiple vibration cavities.

17. The ultrasonic transducer according to claim 15, wherein: In the transducer unit, the plurality of cavities are arranged into a plurality of rows and columns; The first connecting line connects the second electrode sub-sections located in the same row along the row direction of the multiple vibration cavities, and connects the second electrode sub-sections located in the same column along the column direction of the multiple vibration cavities; the second connecting line connects the first electrode sub-sections arranged parallel to the diagonal direction of the multiple vibration cavities.

18. The ultrasonic transducer according to claim 15, wherein: In the transducer unit, the plurality of cavities are arranged into a plurality of rows and columns; The first connecting line connects the second electrode sub-sections arranged parallel to the diagonal direction of the multiple vibration cavities; the second connecting line connects the first electrode sub-sections located in the same row along the row direction of the multiple vibration cavities, and connects the first electrode sub-sections located in the same column along the column direction of the multiple vibration cavities.

19. The ultrasonic transducer according to any one of claims 1 to 18, wherein: The driving backplane includes a plurality of driving circuits; one driving circuit corresponds to one transducer unit, and the driving circuit is electrically connected to the corresponding transducer unit; the driving circuit includes a thin film transistor.

20. The ultrasonic transducer of claim 19, wherein: The driving backplane further comprises a substrate; the substrate is located at a side of the driving circuit away from the transducer unit; the substrate is made of glass or polyimide.

21. A display panel, wherein: Comprising the ultrasonic transducer according to any one of claims 1 to 20.

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