Ultrasonic transducer and preparation method thereof, ultrasonic fingerprint module and electronic equipment

Abstract

The embodiment of the invention provides an ultrasonic transducer, a preparation method of the ultrasonic transducer, an ultrasonic fingerprint module and electronic equipment. The preparation method of the ultrasonic transducer comprises the following steps: forming a bottom electrode on the upper surface of a substrate, and forming a piezoelectric layer covering the bottom electrode on the upper surface of the substrate; a top electrode material layer covering the piezoelectric layer is formed above the substrate; a second material layer part of the top electrode material layer is removed, a first material layer part which is preset for forming a top electrode in the top electrode material layer is reserved, and the second material layer part is the other part, except the first material layer part, in the top electrode material layer; and forming a top electrode based on the reserved part of the first material layer to obtain the ultrasonic transducer. According to the technical scheme provided by the embodiment of the invention, the ultrasonic transducer with relatively good performance can be prepared.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of ultrasonic transducers, and in particular to an ultrasonic transducer and a method for preparing the same, an ultrasonic fingerprint module, and an electronic device. Background Art

[0002] Ultrasonic transducers use the mechanical-electrical conversion characteristics of piezoelectric materials. On the one hand, they emit ultrasonic signals through the voltage excitation output by the driving circuit, and on the other hand, they convert the ultrasonic signals reflected from the outside world into electrical signals, thereby obtaining external sensing surface information. They can be widely used in areas including but not limited to biometric identification (for example, an example application can be used in ultrasonic fingerprint modules to collect fingerprint information for fingerprint identification). The performance of ultrasonic sensors obtained by existing preparation processes is poor. Therefore, it is necessary to improve the preparation process of ultrasonic transducers to improve the performance of the prepared ultrasonic transducers. Summary of the invention

[0003] The embodiments of the present application provide an ultrasonic transducer and a method for manufacturing the same, an ultrasonic fingerprint module, and an electronic device.

[0004] According to a first aspect of an embodiment of the present application, a method for preparing an ultrasonic transducer is provided, comprising: forming a bottom electrode on the upper surface of a substrate, and forming a piezoelectric layer covering the bottom electrode above the substrate; forming a top electrode material layer covering the piezoelectric layer above the substrate; removing a second material layer portion of the top electrode material layer, and retaining a first material layer portion of the top electrode material layer intended for forming a top electrode, wherein the second material layer portion is the other portion of the top electrode material layer except the first material layer portion; and forming a top electrode based on the retained first material layer portion to obtain the ultrasonic transducer.

[0005] In some optional embodiments, an angle between at least one outer sidewall of the top electrode and a normal line of the substrate is less than or equal to 45°.

[0006] In some optional embodiments, an angle between at least one outer sidewall of the top electrode and a normal line of the substrate is less than or equal to 5°.

[0007] In some optional embodiments, the method further comprises: preparing a protective layer covering at least a portion of the top electrode.

[0008] In some optional embodiments, the second material layer portion of the top electrode material layer is removed, and the first material layer portion of the top electrode material layer predetermined for forming the top electrode is retained, comprising: placing a first mask including at least one first light leakage area and at least one first light shading area above the top electrode material layer for a first exposure treatment, converting the second material layer portion below the first light leakage area into a first chemical component through the first exposure treatment, and preventing the first material layer portion below the first light shading area from being converted into the first chemical component during the first exposure treatment through the mask of the first light shading area; removing the second material layer portion that has been converted into the first chemical component, and retaining the first material layer portion; forming a top electrode based on the retained first material layer portion to obtain the ultrasonic transducer comprises: using the retained first material layer portion as the top electrode to obtain the ultrasonic transducer.

[0009] In some optional embodiments, removing the portion of the second material layer that has been converted into the first chemical component includes: dissolving the portion of the second material layer that has been converted into the first chemical component by a first developing solution, and removing the dissolved portion of the second material layer.

[0010] In some optional embodiments, removing the dissolved portion of the second material layer includes: cleaning the top electrode material layer to remove the dissolved portion of the second material layer.

[0011] In some optional embodiments, the method of removing the second material layer portion of the top electrode material layer and retaining the first material layer portion of the top electrode material layer intended for forming the top electrode comprises: placing a third mask including at least one third light leakage area and at least one third light shading area above the top electrode material layer for a third exposure treatment, converting the first material layer portion below the third light leakage area into a third chemical component through the third exposure treatment, and preventing the second material layer portion below the third light shading area from being converted into the third chemical component during the third exposure treatment through the mask of the third light shading area; removing the second material layer portion that has not been converted into the third chemical component, and retaining the first material layer portion that has been converted into the third chemical component; forming a top electrode based on the retained first material layer portion to obtain the ultrasonic transducer comprises: using the retained first material layer portion that has been converted into the third chemical component as the top electrode to obtain the ultrasonic transducer.

[0012] In some optional embodiments, removing the portion of the second material layer that has not been converted into the third chemical component includes: dissolving the portion of the second material layer that has not been converted into the third chemical component by a third developing solution, and removing the dissolved portion of the second material layer.

[0013] In some optional embodiments, removing the dissolved portion of the second material layer includes: cleaning the top electrode material layer to remove the dissolved portion of the second material layer.

[0014] In some optional embodiments, removing the second material layer portion of the top electrode material layer and retaining the first material layer portion of the top electrode material layer predetermined for forming the top electrode includes: forming a barrier layer covering the upper surface of the top electrode material layer; removing the second barrier layer portion of the barrier layer covering the second material layer portion to expose the second material layer portion, and retaining the first barrier layer portion of the barrier layer covering the first material layer portion; removing the exposed second material layer portion through an etching process, and preventing the first material layer portion below the first barrier layer portion from being removed during the etching process by blocking the first barrier layer portion, so as to retain the first material layer portion; forming a top electrode based on the retained first material layer portion to obtain the ultrasonic transducer includes: using the retained first material layer portion as the top electrode to obtain the ultrasonic transducer.

[0015] In some optional embodiments, the second barrier layer portion covering the second material layer portion is removed to expose the second material layer portion and the first barrier layer portion covering the first material layer portion is retained, comprising: a second light mask comprising at least one second light leakage area and at least one second light shading area is placed above the barrier layer for a second exposure treatment, wherein the second barrier layer portion of the barrier layer below the second light leakage area is converted into a second chemical component through the second exposure treatment, and the first barrier layer portion below the second light shading area is prevented from being converted into the second chemical component during the second exposure treatment through the mask of the second light shading area; the second barrier layer portion that has been converted into the second chemical component is removed to expose the second material layer portion and the first barrier layer portion of the barrier layer covering the first material layer portion is retained.

[0016] In some optional embodiments, removing the portion of the second barrier layer that has been converted into a second chemical component includes: dissolving the portion of the second barrier layer that has been converted into a second chemical component by a second developing solution, and removing the dissolved portion of the second barrier layer.

[0017] In some optional embodiments, the forming of the barrier layer covering the upper surface of the top electrode material layer includes: providing a photoresist covering the upper surface of the top electrode material layer, and curing the photoresist to form the barrier layer.

[0018] In some optional embodiments, the second barrier layer portion covering the second material layer portion is removed to expose the second material layer portion and the first barrier layer portion covering the first material layer portion is retained, comprising: a fourth light mask comprising at least one fourth light leakage area and at least one fourth light shading area is placed above the barrier layer for a fourth exposure treatment, wherein the first barrier layer portion of the barrier layer below the fourth light leakage area is converted into a fourth chemical component through the fourth exposure treatment, and the second barrier layer portion below the fourth light shading area is prevented from being converted into the fourth chemical component during the fourth exposure treatment through the mask of the fourth light shading area; the second barrier layer portion that has not been converted into the fourth chemical component is removed to expose the second material layer portion and the first barrier layer portion that has been converted into the fourth chemical component is retained.

[0019] In some optional embodiments, the portion of the second barrier layer that has not been converted into the fourth chemical component is removed, comprising: dissolving the portion of the second barrier layer that has not been converted into the fourth chemical component by a fourth developing solution, and removing the dissolved portion of the second barrier layer.

[0020] In some optional embodiments, after forming the piezoelectric layer, the implementation temperature of the preparation method is controlled below 135°C.

[0021] In some optional embodiments, the material used to prepare the top electrode material layer includes at least one of a silver paste and a PEDOT-based conductive ink material.

[0022] According to a second aspect of an embodiment of the present application, an ultrasonic transducer is provided, which is prepared by the method for preparing an ultrasonic transducer as described in any one of the first aspects, and the ultrasonic transducer comprises: a substrate, a bottom electrode, a piezoelectric layer and a top electrode; the bottom electrode is located on the upper surface of the substrate, the piezoelectric layer is located above the substrate and covers the bottom electrode, and at least a portion of the top electrode is located above the piezoelectric layer; the top electrode is used to be applied with an excitation signal to excite the piezoelectric layer to emit an ultrasonic signal, and the bottom electrode is used to receive an ultrasonic detection signal generated between the top electrode and the bottom electrode when the returned ultrasonic signal acts on the piezoelectric layer.

[0023] According to a third aspect of the embodiments of the present application, an ultrasonic fingerprint module is provided, comprising: the ultrasonic transducer provided in the aforementioned second aspect.

[0024] According to a fourth aspect of the embodiments of the present application, an electronic device is provided, comprising: the ultrasonic transducer provided by the second aspect, or the ultrasonic fingerprint module provided by the third aspect.

[0025] The preparation scheme of the ultrasonic transducer in the embodiment of the present application, on the one hand, can form a piezoelectric layer covering the bottom electrode above the substrate, and form a top electrode material layer covering the piezoelectric layer above the substrate, and then remove the second material layer portion of the top electrode material layer except the first material layer portion predetermined to form the top electrode, and retain the first material layer portion for forming the top electrode, so that an ultrasonic transducer including a substrate, a bottom electrode, a piezoelectric layer and a top electrode can be effectively prepared; on the other hand, since the present application forms a top electrode material layer covering the piezoelectric layer above the substrate, and then selectively removes different portions of the top electrode material layer The top electrode is formed based on the retained part, so that the quality of the formed top electrode can be more controllable, and the quality stability of the top electrode can be better, which is beneficial to ensure the performance of the top electrode, thereby effectively improving the performance of the prepared ultrasonic transducer and making the preparation process of the ultrasonic transducer simpler and easier to control; on the other hand, compared with the scheme of preparing the top electrode by multi-layer silk screen printing in the related art, this scheme can also save more cumbersome silk screen operation steps when forming the top electrode of the required target thickness, which can effectively reduce the process difficulty and time cycle, and reduce the probability of production abnormalities. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0027] Figure 1 A schematic diagram of a preparation process of an ultrasonic transducer according to an example of the related art is shown.

[0028] Figure 2A A schematic diagram of an ultrasonic transducer according to an example of the present application is shown.

[0029] Figure 2B A schematic diagram of an ultrasonic transducer according to an example of the present application is shown.

[0030] Figure 2C Shows Figure 2A A schematic plan view of the ultrasonic transducer shown in FIG.

[0031] Figure 3 A flow chart of a method for preparing an ultrasonic transducer according to an example of the present application is shown.

[0032] Figure 4A The preparation method shown in this application Figure 2A Schematic diagram of an example preparation process of an ultrasonic transducer.

[0033] Figure 4B The preparation method shown in this application Figure 2A Schematic diagram of another example preparation process of an ultrasonic transducer.

[0034] Figure 4C The preparation method shown in this application Figure 2B Schematic diagram of an example of the preparation process of an ultrasonic transducer

[0035] Figure 4D The preparation method shown in this application Figure 2A A schematic diagram of another example of a preparation process of an ultrasonic transducer.

[0036] Figure 5A A flow chart showing an optional implementation of removing a portion of the second material layer and retaining a portion of the first material layer in the present application.

[0037] Figure 5B A flow chart showing another optional implementation of removing a portion of the second material layer and retaining a portion of the first material layer in the present application.

[0038] Figure 6 A flow chart showing another optional implementation of removing a portion of the second material layer and retaining a portion of the first material layer in the present application.

[0039] Fig. 7A An optional flowchart of step S304 in the present application is shown.

[0040] Figure 7B Another optional flow chart of step S304 in the present application is shown.

[0041] Fig. 8A A schematic diagram showing the angle between the outer sidewall of the top electrode and the normal line of the substrate in an example of the present application is shown.

[0042] Figure 8B A schematic diagram showing the angle between the outer sidewall of the top electrode and the normal line of the substrate of another example in the present application is shown.

[0043] Fig. 9 A schematic block diagram of an example ultrasonic fingerprint module in the present application is shown.

[0044] Fig. 10AA schematic block diagram of an electronic device according to an example of the present application is shown.

[0045] Fig. 10B A schematic block diagram of another example electronic device in the present application is shown.

[0046] Fig.11 A schematic diagram showing an example of an ultrasonic transducer bonded under a screen of an electronic device in the present application.

[0047] Description of reference numerals:

[0048] 100. ultrasonic transducer; 10. substrate; 20. bottom electrode; 30. piezoelectric layer; 40. top electrode; 41. top electrode material layer; 51. first light mask; 511. first light shielding area; 512. first light leakage area; 52. second light mask; 521. second light shielding area; 522. second light leakage area; 53. third light mask; 531. third light shielding area; 532. third light leakage area; 54. fourth light mask; 541. fourth light shielding area; 542. fourth light leakage area; 60. excitation electrode; 70. protective layer; 80. blocking layer; 81. first blocking layer portion; 82. second blocking layer portion; 90. pad area; 200. ultrasonic fingerprint module; 300. electronic device; 310. adhesive layer; 320. screen. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the embodiments of the present application should fall within the scope of protection of the embodiments of the present application.

[0050] Ultrasonic transducers use the mechanical-electric conversion characteristics of piezoelectric materials. On the one hand, they emit ultrasonic signals through the voltage excitation output by the driving circuit, and on the other hand, they convert the ultrasonic signals reflected from the outside world into electrical signals, thereby obtaining information about the external sensing surface. They can be widely used in fields including but not limited to biometric identification (for example, an example application can be used in ultrasonic fingerprint modules, which can collect fingerprint information for fingerprint identification). For example, ultrasonic transducers are applied to ultrasonic fingerprint modules and set in specific areas of the screens of electronic devices including but not limited to smartphones. They can be used for fingerprint identification, and the distribution information of the peaks and valleys of fingerprints can be obtained. Through the difference in the strength of the reflected ultrasonic signals corresponding to the peaks and valleys, signal processing is performed to obtain fingerprint images and realize user identity authentication. The fingerprint identification system based on ultrasonic transducer sensing technology has the advantage that it is not only relatively insensitive to interference from wet, dry or dirty fingers, but also can pass through thick glass screens and other materials, such as screen protectors. Therefore, ultrasonic transducers provide more design freedom for electronic devices and can enhance the anti-interference and safety of products. In some exemplary ultrasonic transducer structures, there are circuit structures for transmitting ultrasonic excitation signals and processing ultrasonic echo signals, as well as a piezoelectric material layer with a high piezoelectric coefficient, that is, generally composed of a bottom electrode, a piezoelectric layer, and a top electrode. The performance of ultrasonic sensors obtained by the existing preparation process is poor, so it is necessary to improve the preparation process of ultrasonic transducers to improve the performance of the prepared ultrasonic transducers.

[0051] Combine the following Figure 1 The schematic diagram of the preparation process shown in FIG. 1 introduces a preparation process of an ultrasonic transducer in the related art. It should be understood that Figure 1 The related technologies shown in the preparation process are not necessarily prior art. Figure 1 As shown, first, a bottom electrode 20' and a piezoelectric layer 30' covering the bottom electrode 20' are formed on the upper surface of the substrate 10'; then, a top electrode 40' can be prepared on the piezoelectric layer 30' by screen printing (abbreviated as silk screen printing) using silver paste as the top electrode material. According to the thickness requirement of the top electrode 40', limited by the technical characteristics and process capabilities of the silk screen printing process, a single printing usually cannot make the top electrode 40' reach the required thickness, so it is necessary to stack multiple layers of silk screen printing to achieve the required target thickness (for example, 3 to 5 layers of silk screen printing can be used as an example). After the top electrode 40' is prepared, an ultrasonic transducer can be obtained. Figure 1 In the example shown, the top electrode 40' is prepared by at least 4 layers of screen printing. Figure 1As shown, in the process of preparing the ultrasonic transducer, an excitation electrode 60' and a pad area 90' can also be formed on the substrate 10', wherein the pad area 90' is used to connect to an external circuit, and the excitation electrode 60' is electrically connected to the pad area 90' and the top electrode 40', so as to obtain the excitation signal emitted by the external circuit through the pad area 90' and transmit it to the top electrode 40', so as to control the piezoelectric layer 30'. The pad area 90' may include a plurality of pads, and the excitation electrode 60' may be connected to a part of the pads, and the other pads of the pad area 90' may be used for the lead-out and access of other electrical signals, etc. For example, the specific steps of multi-layer silk screen printing are generally: firstly, the first layer of silk screen printing is performed to print the first layer of silver paste, and after the silver paste is baked and cured, the second layer of silk screen printing is performed, and then the baking and curing is performed, and then the third, fourth or more layers of silk screen printing are performed in sequence and the silver paste is baked and cured, until the target thickness required for the top electrode 40' is reached. As shown Figure 1 The preparation process shown in the figure has too many operation steps to achieve the required target thickness by preparing the top electrode 40' through multi-layer silk screen printing, and the silk screen screens used for each layer of silk screen printing are mostly of different screen designs, resulting in the need to switch screen production for each silk screen printing. Therefore, the process is more difficult, the time cycle is longer, and the probability of production abnormalities is higher.

[0052] about Figure 1 The multi-layer screen printing method for preparing the top electrode of the ultrasonic transducer is shown. The technical characteristics of the screen printing process determine its process capabilities. For example: 1. The screen printing material needs to have a certain fluidity, so that the screen printing material can smoothly pass through the mesh of the screen printing screen and be printed on the substrate to be printed. If the viscosity is too high, printing will be difficult, and if the viscosity is too low, the material will easily overflow and controllable printing patterns cannot be achieved; 2. The screen printing screen has different mesh counts (mesh count definition: mesh count is the number of mesh holes per inch area, which can indicate the density between the silk threads). The higher the mesh count, the denser the screen, the smaller the mesh, the worse the passability of the screen printing material, the thinner the printing thickness obtained by a single printing, but the smaller the printing roughness, the smoother the surface of the material obtained by the screen printing, on the contrary, if the mesh is larger, the passability of the screen printing material is better, the printing thickness obtained by a single printing is thicker, but the greater the printing roughness, the more uneven the surface of the material obtained by the screen printing. Based on the above characteristics, if you want to obtain a top electrode 40' that meets product requirements, you need to comprehensively consider the viscosity of the screen printing material (such as silver paste), the mesh number of the screen, and the number of printings. If you want to obtain a lower material roughness for the top electrode 40', the mesh number of the screen printing plate cannot be too low, but the thickness obtained by a single printing will be limited, that is, the roughness and thickness of the material obtained by screen printing are usually mutually restrained; it is difficult for the top electrode 40' to achieve the required target thickness in a single printing, so Figure 1The solution of the related art shown is generally to achieve a balance between roughness and thickness by combining screen printing plates of different mesh sizes and performing multiple screen printing. Obviously, the processing process of the above multiple printings is relatively cumbersome, the processing cycle is long, the steps are cumbersome, and the probability of production abnormalities is increased.

[0053] In addition, the cleanliness of different layers of silk-screened materials needs to be controlled, and foreign matter introduced in each layer may reduce the use effect of the ultrasonic transducer (for example, if the ultrasonic transducer is applied to the ultrasonic fingerprint module, the foreign matter introduced in each layer may cause the image recognition to fail, resulting in poor fingerprint recognition effect). The boundary position of different layers of silk-screened materials is misaligned due to the alignment deviation, and the fluctuation of the viscosity of the superimposed material itself and the flow in the physical state are easy to make the boundary position unfixed and irregular, which will directly lead to the appearance of the ultrasonic transducer. Failure. Furthermore, if the edge of the uncured material overflows to the electrically sensitive area on the substrate, it will cause a short circuit or discharge breakdown, which is easy to directly cause the acoustic performance of the piezoelectric layer of the ultrasonic transducer to fail. In addition, due to the technical characteristics of the multi-layer silk-screen printing process, the silver paste at the boundary of the top electrode presents a gentle slope morphology after leveling. This boundary morphology will produce a wider diffraction echo for the transmission of the ultrasonic signal, which will interfere with the use effect of the ultrasonic transducer to a certain extent (for example, if the ultrasonic transducer is applied to the ultrasonic fingerprint module, it can interfere with the fingerprint image quality to a certain extent and affect the accuracy of fingerprint recognition). Moreover, the more silk-screen layers there are, the greater the overall thickness tolerance of the top electrode. The thickness fluctuation will affect the frequency change when the ultrasonic transducer is used (for example, if the ultrasonic transducer is applied to an ultrasonic fingerprint module, it can be ultrasonic fingerprint recognition), which is not conducive to controlling within the required target frequency range, thereby reducing the use effect. The above-mentioned appearance and performance failures will have a significant impact on the processing yield of the ultrasonic transducer and affect the production cost of the ultrasonic transducer.

[0054] It should be understood that the ultrasonic transducer preparation scheme of the present invention does not adopt the method of preparing the top electrode by multi-layer silk screen printing, but through a series of innovative steps, the second material layer portion of the top electrode material layer covering the piezoelectric layer is removed except for the first material layer portion predetermined to form the top electrode, and the top electrode is formed based on the retained first material layer portion, which can at least partially avoid the above-mentioned Figure 1 The defects of the preparation scheme shown are eliminated, and the performance of the produced ultrasonic transducer is effectively improved, and the difficulty of the preparation process of the ultrasonic transducer is reduced.

[0055] The specific implementation of the technical solution of the embodiment of the present application is described below in conjunction with the accompanying drawings. It should be noted that for the convenience of illustration in each of the drawings, each structure may not be drawn according to the actual scale. Each of the drawings does not serve as any limitation to the embodiment of the present application.

[0056] Here, the structure of the ultrasonic transducer prepared in the embodiment of the present application is briefly introduced, so as to facilitate the specific description of its preparation method below. Figure 2A and Figure 2B In the example shown, an ultrasonic transducer 100 prepared by the preparation method of the first aspect in the embodiment of the present application comprises: a substrate 10, a bottom electrode 20, a piezoelectric layer 30 and a top electrode 40; the bottom electrode 20 is located on the upper surface of the substrate 10, the piezoelectric layer 30 is located above the substrate 10 and covers the bottom electrode 20, and at least a portion of the top electrode 40 is located above the piezoelectric layer 30; the top electrode 40 is used to be applied with an excitation signal to excite the piezoelectric layer 30 to emit an ultrasonic signal, and the bottom electrode 20 is used to receive an ultrasonic detection signal generated between the top electrode 40 and the bottom electrode 20 when the returned ultrasonic signal acts on the piezoelectric layer 30.

[0057] Optionally, the excitation signal may be an alternating current signal. Optionally, when the ultrasonic transducer 100 is used in an ultrasonic fingerprint module, the ultrasonic detection signal may be used to obtain a fingerprint image of a finger.

[0058] Figure 3 A flowchart of a method for preparing an ultrasonic transducer according to an example of the present application is shown. Figure 3 As shown, the method for preparing the ultrasonic transducer includes steps S102, S104, S106 and S108, specifically:

[0059] S102: forming a bottom electrode on the upper surface of the substrate, and forming a piezoelectric layer covering the bottom electrode above the substrate.

[0060] Optionally, the substrate 10 may be a silicon-based substrate or a TFT (Thin Film Transistor) substrate, or other types of substrates if required.

[0061] In the present application, the bottom electrode 20 may be formed on the upper surface of the substrate 10 by any suitable method, including but not limited to deposition, etching and the like.

[0062] Optionally, the piezoelectric layer 30 may include any piezoelectric material. For example, it may include at least one of PVDF (polyvinylidene difluoride) material, lead zirconate titanate material, and lithium niobate material. PVDF material may include PVDF, PVDF copolymer, etc. In the present application, the piezoelectric layer 30 may be formed above the substrate 10 in any suitable manner, which is not particularly limited herein. For example, it may be achieved by methods including but not limited to screen printing, coating, dry film lamination, etc., or it may be achieved by physical or chemical vapor deposition methods such as sputtering and evaporation.

[0063] For example, refer to Figure 4A , Figure 4B , Figure 4C and Figure 4D The schematic diagram of the preparation process of the ultrasonic transducer 100 shown in FIG. 1 shows that a plurality of ultrasonic transducers 100 can be prepared from a large substrate 10. Figure 4A , Figure 4B , Figure 4C and Figure 4D In the figure, only an example of preparing two ultrasonic transducers 100 through a large substrate 10 is shown. After the preparation is completed, the entire large substrate 10 can be separated to obtain two ultrasonic transducers 100. It should be understood that the actual preparation is not limited to this, and more ultrasonic transducers 100 can be prepared. The examples in the figure are not intended to limit the embodiments of the present application.

[0064] Optionally, in the present application, after forming the piezoelectric layer 30, the temperature of the subsequent steps of the method for preparing the ultrasonic transducer of the present application is controlled to be below 135° C. Within this temperature range, the risk of the piezoelectric performance of the piezoelectric layer 30 being reduced or failing due to high temperature is avoided, the function of the piezoelectric layer 30 is ensured, and the performance of the prepared ultrasonic transducer 100 is ensured.

[0065] Preferably, after forming the piezoelectric layer 30, the temperature of the subsequent steps of the method for preparing the ultrasonic transducer of the present application is controlled at 70° C. to 110° C. Within this temperature range, the risk of the piezoelectric performance of the piezoelectric layer 30 being reduced or failing due to high temperature can be better avoided, the function of the piezoelectric layer 30 can be better guaranteed, and the performance of the prepared ultrasonic transducer 100 can be better guaranteed.

[0066] S104: forming a top electrode material layer covering the piezoelectric layer above the substrate.

[0067] The top electrode material layer 41 can be used to prepare the top electrode 40. The top electrode material layer 41 can be formed by any suitable method. For example, the top electrode material can be used to form the top electrode material layer 41 covering the piezoelectric layer 30 on the substrate 10 by a series of solution coating methods such as spin coating, spray coating, roller coating, slit coating, screen printing, etc., or by dry film lamination, which is not specifically limited here.

[0068] For example, taking spin coating as an example, a top electrode material (such as slurry) may be used to spin coat a whole layer of top electrode material on the upper surface of the substrate 10 to form a top electrode material layer 41 covering the piezoelectric layer 30 .

[0069] Optionally, the material for preparing the top electrode material layer 41 may include at least one of silver and PEDOT (poly 3,4-ethylenedioxythiophene) materials. Alternatively, other conductive materials may be used, which are not limited here. For example, in some optional embodiments, the top electrode material for preparing the top electrode material layer 41 may be at least one of silver paste and PEDOT-based conductive ink materials.

[0070] In some optional embodiments, in order to meet the requirements of the first exposure treatment in the optional embodiments below, the top electrode material may have exposure and development characteristics so that the second material layer portion of the top electrode material layer 41 can be converted into the first chemical composition after the first exposure treatment.

[0071] In some optional embodiments, in order to adapt to the requirements of the third exposure treatment in the optional embodiments below, the top electrode material may have exposure and development characteristics so that the first material layer portion of the top electrode material layer 41 can be converted into a third chemical composition after the third exposure treatment.

[0072] Optionally, the thickness of the top electrode material layer 41 formed above the substrate 10 to cover the piezoelectric layer 30 can be the same as the desired target thickness of the top electrode 40, so that in a subsequent step, the second material layer portion can be removed and the top electrode 40 formed by retaining the first material layer portion can be the desired target thickness.

[0073] S106: removing the second material layer portion of the top electrode material layer, and retaining the first material layer portion of the top electrode material layer that is intended to form the top electrode, wherein the second material layer portion is the other portion of the top electrode material layer except the first material layer portion.

[0074] S108: forming a top electrode based on the remaining portion of the first material layer to obtain an ultrasonic transducer.

[0075] In the present application, the portion of the top electrode material layer 41 that needs to be retained (i.e., the first material layer portion) and the portion that needs to be removed (i.e., the second material layer portion) can be pre-designed, and the portion of the second material layer that needs to be removed can be accurately removed by a suitable method, and the portion of the first material layer that needs to be retained can be retained. Then, the required top electrode 40 can be formed based on the retained first material layer portion, and then the ultrasonic transducer 100 can be obtained.

[0076] Based on this, the embodiment of the present application, through the preparation method of the above steps S102 to S108, on the one hand, can form a piezoelectric layer covering the bottom electrode on the upper surface of the substrate, and form a top electrode material layer covering the piezoelectric layer above the substrate, and then remove the second material layer portion of the top electrode material layer except for the first material layer portion predetermined to form the top electrode, and retain the first material layer portion for forming the top electrode, so that an ultrasonic transducer including a substrate, a bottom electrode, a piezoelectric layer and a top electrode can be effectively prepared; on the other hand, since the present application is to form a top electrode material layer covering the piezoelectric layer above the substrate, and then remove different portions of the top electrode material layer The top electrode is formed based on the retained part, so that the quality of the formed top electrode can be more controllable, and the quality stability of the top electrode can be better, which is beneficial to ensure the performance of the top electrode, thereby effectively improving the performance of the prepared ultrasonic transducer and making the preparation process of the ultrasonic transducer simpler and easier to control; on the other hand, compared with the scheme of preparing the top electrode by multi-layer silk screen printing in the related art, this scheme can also save more cumbersome silk screen operation steps when forming the top electrode of the required target thickness, which can effectively reduce the process difficulty and time cycle, and reduce the probability of production abnormalities.

[0077] The specific implementation of step S106 is not limited in the present application. A variety of optional implementations can be used to form the top electrode, and several optional implementations are described in detail below.

[0078] In some optional embodiments, referring to Figure 5A In the flowchart shown in FIG. 1 , the method of removing the second material layer portion and retaining the first material layer portion in step S106 may include steps S202A and S204A, specifically:

[0079] S202A: placing a first photomask including at least one first light leakage region and at least one first light shielding region above the top electrode material layer for a first exposure process, converting a portion of the second material layer below the first light leakage region into a first chemical component through the first exposure process, and preventing a portion of the first material layer below the first light shielding region from being converted into the first chemical component during the first exposure process through the mask of the first light shielding region;

[0080] S204A: removing the portion of the second material layer that has been converted into the first chemical composition, and retaining the portion of the first material layer.

[0081] Optionally, based on steps S202A to S204A, step S108 may include: using the retained first material layer portion as the top electrode 40 to obtain the ultrasonic transducer 100 .

[0082] Based on this, through the above optional implementation, the top electrode material layer 41 can be subjected to a first exposure treatment through the first mask 51, so that the second material layer portion located below the first light leakage area 512 in the top electrode material layer 41 is converted into the first chemical component, and then the second material layer portion that has been converted into the first chemical component is removed, and the first material layer portion located below the first light shielding area 511 in the top electrode material layer 41 can be retained, so that the retained first material layer portion can be used as the top electrode 40, thereby effectively preparing the ultrasonic transducer 100. Therefore, in the above optional implementation of the present application, different portions of the top electrode material layer 41 are selectively removed and retained by the first exposure treatment, so that the top electrode material layer 41 can effectively form the top electrode 40, compared with Figure 1 With respect to the multi-layer silk-screen printing method in the related art, the boundary position accuracy of the top electrode 40 of the ultrasonic transducer 100 prepared in the above optional implementation scheme of the present application is higher, and the morphology of the top electrode 40 is more regular and neat, which can make the quality stability of the top electrode better, thereby being beneficial to ensuring the performance of the top electrode 40, thereby effectively improving the performance of the prepared ultrasonic transducer 100, and improving the preparation process, making the preparation process of the ultrasonic transducer 100 simpler and easier to control; in addition, due to the above optional implementation scheme, when forming the top electrode of the required target thickness, many cumbersome silk-screen printing operation steps can also be omitted, which can effectively reduce the process difficulty and time cycle, and reduce the probability of production abnormalities.

[0083] In the present application, due to the presence of the first shading area 511 of the first mask 51, the portion of the first material layer below the first shading area 511 will not be affected by the first exposure process, and thus will not be converted into the first chemical composition, and can still maintain its original state, thereby retaining the first material layer portion of the top electrode material layer 41 to form a top electrode 40 with better performance.

[0084] For example, you can combine Figure 4A To understand the example of the preparation process of the ultrasonic transducer 100 shown, the first photomask 51 may be placed above the top electrode material layer 41, and then the top electrode material layer 41 may be subjected to a first exposure process by using an exposure device through the first photomask 51. The top electrode material layer 41 may have an exposure and development characteristic, and the first exposure process may be achieved by setting a suitable exposure time and exposure energy, so that the second material layer portion of the top electrode material layer 41 below the first light leakage region 512 of the first photomask 51 is converted into a first chemical composition different from that before due to the first exposure process, so that the second material layer portion that has been converted into the first chemical composition may be selectively removed by a suitable method.

[0085] In the present application, the second material layer portion that has been converted into the first chemical component can be removed by any suitable method. In some optional embodiments, in the above step S204A, the second material layer portion that has been converted into the first chemical component can be dissolved by a first developing solution, and the dissolved second material layer portion can be removed.

[0086] The first developing solution can react with the portion of the second material layer that has been converted into the first chemical component, thereby dissolving the portion of the second material layer, thereby facilitating the removal of the dissolved portion of the second material layer.

[0087] It should be understood that the above-mentioned optional embodiment can adopt a solution development method, using a first developing solution to react with the portion of the second material layer that has been converted into the first chemical component after exposure, thereby dissolving the portion of the second material layer that has been converted into the first chemical component, and then using an appropriate method to remove the dissolved portion of the second material layer. Therefore, the purpose of removing the portion of the second material layer can be effectively achieved, so as to retain the portion of the first material layer to form a top electrode 40 with better performance.

[0088] For example, the dissolved second material layer portion can be removed by cleaning the top electrode material layer 41. It should be understood that the dissolved second material layer portion can be effectively removed by cleaning so as to retain the first material layer portion to form the top electrode 40.

[0089] Optionally, when performing the above cleaning process, the entire substrate 10 may be cleaned, thereby cleaning the top electrode material layer 41, which may make the cleaning effect more thorough.

[0090] Optionally, the cleaning process may be carried out by water washing, which can effectively remove the dissolved second material layer portion and has a low process cost.

[0091] In other optional embodiments, other appropriate methods may be used to remove the dissolved portion of the second material layer, which is not specifically limited here.

[0092] Optionally, after the above cleaning process, a baking process may be performed to allow the top electrode 40 formed by the first material layer portion to be better solidified, so as to improve the performance of the prepared ultrasonic transducer 100 .

[0093] In some other optional embodiments, refer to Figure 5B In the flowchart shown in FIG. 1 , the method of removing the second material layer portion and retaining the first material layer portion in step S106 may include steps S202B and S204B, specifically:

[0094] S202B: placing a third photomask including at least one third light leakage region and at least one third light shielding region above the top electrode material layer for a third exposure process, converting a portion of the first material layer below the third light leakage region into a third chemical component through the third exposure process, and preventing a portion of the second material layer below the third light shielding region from being converted into the third chemical component during the third exposure process through the mask of the third light shielding region;

[0095] S204B: removing the portion of the second material layer that has not been converted into the third chemical component, and retaining the portion of the first material layer that has been converted into the third chemical component.

[0096] Optionally, on the basis of steps S202B to S204B, step S108 may include: using the retained portion of the first material layer converted into the third chemical composition as the top electrode 40 to obtain the ultrasonic transducer 100 .

[0097] Based on this, through the above-mentioned optional implementation, the top electrode material layer 41 can be subjected to a third exposure treatment through the third mask 53, so that the first material layer portion located below the third light leakage area 532 in the top electrode material layer 41 is converted into a third chemical composition, and the second material layer portion located below the third light shielding area 531 is prevented from being converted, and then the second material layer portion that has not been converted into the third chemical composition is removed, and the first material layer portion that has been converted into the third chemical composition is retained, so that the retained first material layer portion that has been converted into the third chemical composition can be used as the top electrode, thereby effectively preparing the ultrasonic transducer 100. Therefore, in the above-mentioned optional implementation of the present application, different portions of the top electrode material layer 41 are selectively removed and retained through the third exposure treatment, so that the top electrode material layer 41 can effectively form the top electrode 40, compared with Figure 1 With respect to the multi-layer silk-screen printing method in the related art, the boundary position accuracy of the top electrode 40 of the ultrasonic transducer 100 prepared in the above optional implementation scheme of the present application is higher, and the morphology of the top electrode 40 is more regular and neat, which can make the quality stability of the top electrode better, thereby being beneficial to ensuring the performance of the top electrode 40, thereby effectively improving the performance of the prepared ultrasonic transducer 100, and improving the preparation process, making the preparation process of the ultrasonic transducer 100 simpler and easier to control; in addition, due to the above optional implementation scheme, when forming the top electrode of the required target thickness, many cumbersome silk-screen printing operation steps can also be omitted, which can effectively reduce the process difficulty and time cycle, and reduce the probability of production abnormalities.

[0098] In the present application, due to the presence of the third shading area 531 of the third mask 53, the portion of the second material layer below the third shading area 531 will not be affected by the third exposure process, and thus will not be converted into the third chemical composition, and can still maintain its original state, so that it can be selectively removed later to form a top electrode 40 with better performance.

[0099] For example, you can combine Figure 4C The preparation process of the ultrasonic transducer 100 shown in the figure can be understood by the example that the third photomask 53 can be placed above the top electrode material layer 41, and then the top electrode material layer 41 can be subjected to a third exposure process by using an exposure device through the third photomask 53. The top electrode material layer 41 can have an exposure and development characteristic, and the third exposure process can be achieved by setting a suitable exposure time and exposure energy, so that the first material layer portion of the top electrode material layer 41 below the third light leakage area 532 of the third photomask 53 is converted into a third chemical composition different from that before due to the third exposure process, so that the second material layer portion that has not been converted into the third chemical composition can be selectively removed by a suitable method.

[0100] In the present application, the portion of the second material layer that has not been converted into the third chemical component can be removed by any suitable method. In some optional embodiments, in the above step S204B, the portion of the second material layer that has not been converted into the third chemical component can be dissolved by a third developing solution, and the dissolved portion of the second material layer can be removed.

[0101] The third developing solution can react with the portion of the second material layer that has not been converted into the third chemical component, thereby dissolving the portion of the second material layer, thereby facilitating the removal of the dissolved portion of the second material layer.

[0102] It should be understood that the above-mentioned optional embodiment can adopt a solution development method, using a third developing solution to react with the portion of the second material layer that has not been converted into the third chemical component, thereby dissolving the portion of the second material layer that has not been converted into the third chemical component, and then using an appropriate method to remove the dissolved second material layer portion, thereby effectively achieving the purpose of removing the second material layer portion, so as to retain the first material layer portion that has been converted into the third chemical component to form a top electrode 40 with better performance.

[0103] For example, the dissolved second material layer portion can be removed by cleaning the top electrode material layer 41. It should be understood that the dissolved second material layer portion can be effectively removed by cleaning, so that the first material layer portion converted into the third chemical composition is retained to form the top electrode 40.

[0104] Optionally, when performing the above cleaning process, the entire substrate 10 may be cleaned, thereby cleaning the top electrode material layer 41, which may make the cleaning effect more thorough.

[0105] Optionally, the cleaning process may be carried out by water washing, which can effectively remove the dissolved second material layer portion and has a low process cost.

[0106] In other optional embodiments, other appropriate methods may be used to remove the dissolved portion of the second material layer, which is not specifically limited here.

[0107] Optionally, after the above cleaning process, a baking process may be performed to better solidify the top electrode 40 formed by the first material layer portion converted into the third chemical composition, so as to improve the performance of the prepared ultrasonic transducer 100 .

[0108] In some other optional embodiments, refer to Figure 6 In the flowchart shown in FIG. 1 , the method of removing the second material layer portion and retaining the first material layer portion in step S106 may include the following steps S302, S304 and S306. Specifically:

[0109] S302: forming a barrier layer covering the upper surface of the top electrode material layer.

[0110] The barrier layer 80 may be formed in any suitable manner. For example, the barrier layer material may be used to form the barrier layer 80 covering the upper surface of the top electrode material layer 41 on the upper surface of the top electrode material layer 41 by a series of solution coating methods such as spin coating, spray coating, roller coating, slit coating, screen printing, etc., or by dry film lamination, which is not specifically limited here.

[0111] For example, taking spin coating as an example, a barrier layer material may be used to spin coat a whole layer of barrier layer material on the upper surface of the top electrode material layer 41 to form a barrier layer 80 covering the upper surface of the top electrode material layer 41 .

[0112] Optionally, the material for preparing the barrier layer 80 may be a photoresist. In some optional embodiments, the above step S302 may include: providing a photoresist covering the upper surface of the top electrode material layer 41, and curing the photoresist to form the barrier layer 80. By providing the photoresist to form the barrier layer 80, it is easy to process and manufacture, and the process difficulty of the ultrasonic transducer 100 can be reduced.

[0113] Optionally, when setting the photoresist on the upper surface of the top electrode material layer 41, it can be implemented on the top electrode material layer 41 by a series of solution coating methods such as spin coating, spray coating, roller coating, slit coating, screen printing, etc., or by dry film lamination, which is not specifically limited here.

[0114] Optionally, the barrier layer 80 may be made of an organic material, which may be, for example, at least one of the following materials: polyimide (PI), poly-p-phenylenebenzobisoxazole (PBO), epoxy resin, acrylic resin, and the like. The barrier layer 80 may also be made of an organic siloxane composite material. For example, an organic siloxane composite material may include, but is not limited to, an organic silicon ring, silicone rubber, silicone resin material, and the like. It should be understood that in the present application, the barrier layer 80 may be effectively prepared by using the above-mentioned single material or a mixture of two different materials, so as to facilitate the subsequent preparation of an ultrasonic transducer with better performance.

[0115] S304: removing the second barrier layer portion covering the second material layer portion to expose the second material layer portion, and retaining the first barrier layer portion covering the first material layer portion.

[0116] The second barrier layer portion 82 of the barrier layer 80 covering the second material layer portion can be removed to expose the second material layer portion, so that the exposed second material layer portion can be removed in the subsequent step. The first barrier layer portion 81 of the barrier layer 80 covering the first material layer portion can be retained, so that when the second material layer portion is removed in the subsequent step, the first barrier layer portion 81 can be used to block the first material layer portion below from being removed, so that the first material layer portion can be effectively retained to form a top electrode 40 with better performance.

[0117] The specific implementation method of step S304 is not limited in this application, and it can be implemented in a variety of optional ways. Fig. 7A and Figure 7B The flowchart shown is used to introduce several optional implementations.

[0118] In some optional embodiments, referring to Fig. 7A As shown in the flowchart, the above step S304 includes the following steps S3041A and S3042A, specifically:

[0119] S3041A: placing a second photomask including at least one second light leakage region and at least one second light shielding region on the barrier layer for a second exposure process, converting a second barrier layer portion of the barrier layer below the second light leakage region into a second chemical component through the second exposure process, and preventing a first barrier layer portion below the second light shielding region from being converted into the second chemical component during the second exposure process through the mask of the second light shielding region;

[0120] S3042A: The second barrier layer portion that has been converted into the second chemical composition is removed to expose the second material layer portion, and the first barrier layer portion covering the first material layer portion is retained.

[0121] Based on this, through the optional implementation of the above steps S3041A to S3042A, the blocking layer 80 can be subjected to a second exposure treatment through the second mask 52, so that the second blocking layer portion 82 located below the second light leakage area 522 in the blocking layer 80 is converted into a second chemical composition, and then the second blocking layer portion 82 that has been converted into the second chemical composition is removed to expose the second material layer portion, and the first blocking layer portion 81 located below the second light shielding area 521 in the blocking layer 80 is retained for the subsequent etching process to prepare the top electrode 40. Therefore, in the present application, different parts of the blocking layer 80 are selectively removed and retained by the second exposure treatment, and the retained first blocking layer portion 81 is used to block the subsequent etching process, so that different parts of the top electrode material layer 41 can be selectively removed and retained, so that the top electrode material layer 41 can effectively form the top electrode 40. Compared with Figure 1 In the multi-layer silk-screen printing method in the related technology, the boundary position accuracy of the top electrode 40 of the ultrasonic transducer 100 prepared by the subsequent etching process in the above optional implementation scheme of the present application is higher, and the morphology of the top electrode 40 is more regular and neat, which can make the quality stability of the top electrode better, thereby helping to ensure the performance of the top electrode 40, thereby effectively improving the performance of the prepared ultrasonic transducer 100, and improving the preparation process, making the preparation process of the ultrasonic transducer 100 simpler and easier to control; in addition, due to the above optional implementation scheme, when forming the top electrode of the required target thickness, many cumbersome silk-screen printing operation steps can also be omitted, which can effectively reduce the process difficulty and time cycle, and reduce the probability of production abnormalities; furthermore, in this optional embodiment, the top electrode material layer 41 may not have exposure and development characteristics, thereby reducing the material selection restrictions of the top electrode material layer.

[0122] In the present application, due to the presence of the mask of the second shading area 521 of the second mask 52, the first blocking layer portion 81 below the second shading area 521 will not be affected by the second exposure process, and thus will not be converted into the second chemical composition, and can still maintain its original state, thereby retaining the first blocking layer portion 81 of the blocking layer 80 located above the first material layer portion for subsequent preparation of a top electrode 40 with better performance.

[0123] For example, you can combine Figure 4B To understand the example of the preparation process of the ultrasonic transducer 100 shown, the second mask 52 may be placed above the barrier layer 80, and then the barrier layer 80 may be subjected to a second exposure process through the second mask 52 using an exposure device. The barrier layer 80 may have an exposure and development characteristic, and the second exposure process may be achieved by setting a suitable exposure time and exposure energy, so that the second barrier layer portion 82 of the barrier layer 80 below the second light leakage region 522 of the second mask 52 is converted into a second chemical composition different from that before due to the second exposure process, so that the second barrier layer portion 82 that has been converted into the second chemical composition may be selectively removed using a suitable method.

[0124] In the present application, the second barrier layer portion 82 that has been converted into the second chemical component can be removed by any suitable method. In some optional embodiments, in the above step S3042A, the second barrier layer portion 82 that has been converted into the second chemical component can be dissolved by a second developing solution, and the dissolved second barrier layer portion 82 can be removed.

[0125] The second developing solution may react with the second barrier layer portion 82 that has been converted into the second chemical component, thereby dissolving the second barrier layer portion 82 , thereby facilitating the removal of the dissolved second barrier layer portion 82 .

[0126] It should be understood that the above-mentioned optional embodiment can adopt a solution development method, using a second developing solution to react with the second barrier layer portion 82 that has been converted into the second chemical component after exposure, thereby dissolving the second barrier layer portion 82 that has been converted into the second chemical component, and then using an appropriate method to remove the dissolved second barrier layer portion 82. Therefore, the purpose of removing the second barrier layer portion 82 can be effectively achieved, so as to retain the first barrier layer portion 81 for the subsequent preparation of a top electrode 40 with better performance.

[0127] For example, the dissolved second barrier layer portion 82 can be removed by washing the barrier layer 80. It should be understood that the dissolved second barrier layer portion 82 can be effectively removed by washing so as to retain the first barrier layer portion 81.

[0128] Optionally, when performing the above cleaning process, the entire substrate 10 may be cleaned, thereby cleaning the barrier layer 80, which may make the cleaning effect more thorough.

[0129] Optionally, the cleaning process may be carried out by washing with water, which can effectively remove the dissolved second barrier layer portion 82 and has a low process cost.

[0130] In other optional embodiments, the dissolved second barrier layer portion 82 may be removed by other appropriate methods, which are not specifically limited herein.

[0131] In some other optional embodiments, refer to Figure 7B As shown in the flowchart, the above step S304 includes the following steps S3041B and S3042B, specifically:

[0132] S3041B: placing a fourth photomask including at least one fourth light leakage region and at least one fourth light shielding region above the barrier layer for performing a fourth exposure process, converting a first barrier layer portion of the barrier layer below the fourth light leakage region into a fourth chemical component through the fourth exposure process, and preventing a second barrier layer portion below the fourth light shielding region from being converted into the fourth chemical component during the fourth exposure process through the mask of the fourth light shielding region;

[0133] S3042B: removing the portion of the second barrier layer that has not been converted into the fourth chemical component to expose the second material layer portion, and retaining the portion of the first barrier layer that has been converted into the fourth chemical component.

[0134] Based on this, through the optional implementation of the above steps S3041B to S3042B, the fourth exposure treatment can be performed on the barrier layer 80 through the fourth mask 54, so that the first barrier layer portion 81 located below the fourth light leakage area 542 in the barrier layer 80 is converted into a fourth chemical component, and the second barrier layer portion 82 located below the fourth light shielding area 541 is prevented from being converted during the fourth exposure treatment, and then the second barrier layer portion 82 that has not been converted into the fourth chemical component is removed to expose the second material layer portion, so that the retained first barrier layer portion 81 converted into the fourth chemical component can be retained for the subsequent etching process to prepare the top electrode 40. Therefore, in the present application, different parts of the barrier layer 80 are selectively removed and retained by the fourth exposure treatment. By blocking the retained first barrier layer portion 81 converted into the fourth chemical component, the subsequent etching process can selectively remove and retain different parts of the top electrode material layer 41, so that the top electrode material layer 41 can effectively form the top electrode 40. Compared with Figure 1In the multi-layer silk-screen printing method in the related technology, the boundary position accuracy of the top electrode 40 of the ultrasonic transducer 100 prepared by the subsequent etching process in the above optional implementation scheme of the present application is higher, and the morphology of the top electrode 40 is more regular and neat, which can make the quality stability of the top electrode better, thereby helping to ensure the performance of the top electrode 40, thereby effectively improving the performance of the prepared ultrasonic transducer 100, and improving the preparation process, making the preparation process of the ultrasonic transducer 100 simpler and easier to control; in addition, due to the above optional implementation scheme, when forming the top electrode of the required target thickness, many cumbersome silk-screen printing operation steps can also be omitted, which can effectively reduce the process difficulty and time cycle, and reduce the probability of production abnormalities; furthermore, in this optional embodiment, the top electrode material layer 41 may not have exposure and development characteristics, thereby reducing the material selection restrictions of the top electrode material layer.

[0135] In the present application, due to the presence of the fourth shading area 541 of the fourth mask 54, the second blocking layer portion 82 below the fourth shading area 541 will not be affected by the fourth exposure process, and thus will not be converted into the fourth chemical composition, and can still maintain its original state, so that it can be selectively removed later for the subsequent preparation of a top electrode 40 with better performance.

[0136] For example, you can combine Figure 4D To understand the example of the preparation process of the ultrasonic transducer 100 shown, the fourth mask 54 may be placed above the barrier layer 80, and then the barrier layer 80 may be subjected to a fourth exposure process through the fourth mask 54 using an exposure device. The barrier layer 80 may have an exposure and development characteristic, and the fourth exposure process may be achieved by setting a suitable exposure time and exposure energy, so that the first barrier layer portion 81 of the barrier layer 80 below the fourth light leakage region 542 of the fourth mask 54 is converted into a fourth chemical composition different from that before due to the fourth exposure process, so that the second barrier layer portion 82 that has not been converted into the fourth chemical composition may be selectively removed by a suitable method.

[0137] In the present application, the second barrier layer portion 82 that has not been converted into the fourth chemical component can be removed by any suitable method. In some optional embodiments, in the above step S3042B, the second barrier layer portion 82 that has not been converted into the fourth chemical component can be dissolved by a fourth developing solution, and the dissolved second barrier layer portion 82 can be removed.

[0138] The fourth developing solution may react with the second barrier layer portion 82 that has not been converted into the fourth chemical component, thereby dissolving the second barrier layer portion 82 , thereby facilitating the removal of the dissolved second barrier layer portion 82 .

[0139] It should be understood that the above-mentioned optional embodiment can adopt a solution development method, using a fourth developing solution to react with the second barrier layer portion 82 that has not been converted into the fourth chemical component, thereby dissolving the second barrier layer portion 82 that has not been converted into the fourth chemical component, and then using an appropriate method to remove the dissolved second barrier layer portion 82. Therefore, the purpose of removing the second barrier layer portion 82 can be effectively achieved, so as to retain the first barrier layer portion 81 that has been converted into the fourth chemical component for the subsequent preparation of a top electrode 40 with better performance.

[0140] For example, the dissolved second barrier layer portion 82 can be removed by washing the barrier layer 80. It should be understood that the dissolved second barrier layer portion 82 can be effectively removed by washing so as to retain the first barrier layer portion 81.

[0141] Optionally, when performing the above cleaning process, the entire substrate 10 may be cleaned, thereby cleaning the barrier layer 80, which may make the cleaning effect more thorough.

[0142] Optionally, the cleaning process may be carried out by washing with water, which can effectively remove the dissolved second barrier layer portion 82 and has a low process cost.

[0143] In other optional embodiments, the dissolved second barrier layer portion 82 may be removed by other appropriate methods, which are not specifically limited herein.

[0144] S306: removing the exposed second material layer portion by an etching process, and preventing the first material layer portion below the first barrier layer portion from being removed during the etching process by blocking the first barrier layer portion.

[0145] In the present application, the first barrier layer portion 81 retained in the barrier layer 80 can be used as an etching barrier layer to prevent the first material layer below it from being partially removed by the etching process. In the present application, the etching process can be implemented by a dry etching process or a wet etching process. For example, the dry etching process can be implemented by gas plasma bombardment, and the gas used may include but is not limited to one or more gas combinations such as oxygen, nitrogen, argon, etc. For another example, the wet etching process can be implemented by solution dissolution reaction, and the solvent used may be but is not limited to one or more solvent combinations such as acids, alkalis, and organic matter).

[0146] Optionally, based on the above steps S302 to S306 , step S108 may include: using the retained first material layer portion as the top electrode 40 to obtain the ultrasonic transducer 100 .

[0147] It should be understood that in the present application, by means of an optional implementation method including the above-mentioned steps S302 to S306, the second barrier layer portion 82 of the barrier layer 80 covering the second material layer portion can be removed to expose the second material layer portion, and the first barrier layer portion 81 of the barrier layer 80 covering the first material layer portion can be retained. When the second material layer portion is removed by an etching process, the first barrier layer portion 81 can be used to block the first material layer portion, thereby preventing the first material layer portion from being converted into the second chemical composition, so as to retain the first material layer portion to facilitate the formation of the top electrode 40. Therefore, different portions of the top electrode material layer 41 can be effectively removed and retained selectively, so that the top electrode material layer 41 can effectively form the top electrode 40, compared with Figure 1 With respect to the multi-layer silk-screen printing method in the related art, the boundary position accuracy of the top electrode 40 of the ultrasonic transducer 100 prepared in the above optional implementation scheme of the present application is higher, and the morphology of the top electrode 40 is more regular and neat, which can make the quality stability of the top electrode better, thereby being beneficial to ensuring the performance of the top electrode 40, thereby effectively improving the performance of the prepared ultrasonic transducer 100, and improving the preparation process, making the preparation process of the ultrasonic transducer 100 simpler and easier to control; in addition, due to the above optional implementation scheme, when forming the top electrode of the required target thickness, many cumbersome silk-screen printing operation steps can also be omitted, which can effectively reduce the process difficulty and time cycle, and reduce the probability of production abnormalities.

[0148] Optionally, after the above etching process, cleaning and baking treatment may be performed to make the top electrode 40 formed by the first material layer partly solidify better, so as to improve the performance of the prepared ultrasonic transducer 100 .

[0149] Optionally, in an embodiment of the present application, the material for preparing the top electrode includes a photosensitive silver paste material, which contains metal Ag particles for conduction, components for photosensitive reaction and other additive components; if the photosensitive reaction component is made based on the principle of positive photoresist, during exposure, the dissolution inhibitor generates an acidic substance when exposed to light, causing the resin component to lose dissolution protection, generating a product that is soluble in the developer and is removed by development; the photosensitive part can also be made based on the principle of negative photoresist. During exposure, the photosensitive resin therein will undergo a photocuring reaction during the exposure process, such as cross-linking, polymerization, etc., and the generated cross-linked substance can withstand the erosion of the developer and be retained.

[0150] Figure 4A , Figure 5A The example in the figure is the positive photoresist development method (dissolving the exposed area). Figure 4A Schematic diagram of the preparation process. Figure 5AFor the positive photoresist development method, the top electrode material layer below the first light leakage area 512 undergoes a photochemical reaction to dissolve the inhibitor, which generates an acidic substance when exposed to light, and the resin component loses its dissolution protection. The first chemical component in the above embodiment includes an acidic substance and a resin, which further reacts with the alkaline component in the first developing solution and is dissolved and removed. Figure 4B The positive photoresist development (dissolution of the exposed area) method is also adopted. The second blocking layer portion 82 below the second light leakage area 522 undergoes a photochemical reaction. The dissolution inhibitor generates an acidic substance upon exposure to light. The resin component loses its dissolution protection. The second chemical component includes the acidic substance and the resin, etc., which further reacts with the alkaline component in the second developing solution, so that the second blocking layer portion 82 below the second light leakage area 522 is dissolved and removed.

[0151] Figure 4C , Figure 5B An example is the negative photoresist development method (unexposed areas are dissolved). Figure 4C Schematic diagram of the preparation process. Figure 5B : is a flow chart of the preparation steps. For the negative photoresist development method, the top electrode material layer below the third light leakage area 532 undergoes a photochemical reaction (cross-linking and curing) to become a third chemical component, and the third chemical component is a cross-linked and cured polymer, which can withstand the erosion of the third developing solution and will not be dissolved and retained. Since the top electrode material layer below the third light shielding area 531 does not undergo a cross-linking reaction, the top electrode material layer below the third light shielding area 531 is dissolved in the alkaline third developing solution, so that the top electrode material layer below the third light shielding area 531 is removed. Figure 4D The negative photosensitive film development (dissolution of unexposed areas) method is also adopted. The first barrier layer portion 81 below the fourth light leakage area 542 undergoes a photocuring reaction (cross-linking, polymerization reaction) to become a fourth chemical component. The fourth chemical component is a cross-linked and cured polymer and will not be removed by the fourth developing solution. Since the second barrier layer portion 82 below the fourth light shading area 541 does not undergo a cross-linking reaction, the second barrier layer portion 82 below the fourth light shading area 541 is dissolved in the alkaline fourth developing solution and removed.

[0152] In the above embodiment, Figure 4A and Figure 4C It can be seen that the preparation of the top electrode 40 can be carried out by positive photoresist development or negative photoresist development. Figure 4B and Figure 4D It can be known that the first barrier layer portion 81 can also be prepared by using a positive photoresist development method or a negative photoresist development method, and then the top electrode 40 is formed by an etching process.

[0153] In some optional embodiments, the angle between at least one outer sidewall of the top electrode 40 obtained in the embodiment of the present application and the normal line of the substrate 10 is less than or equal to 45°.

[0154] for Figure 1 As for the multi-layer silk-screen printing method for preparing the top electrode shown, due to the technical characteristics of the silk-screen printing process, the silver paste at the boundary of the top electrode presents a gentle slope after leveling. This boundary morphology will produce a wider diffraction echo for the transmission of the ultrasonic signal, which will interfere with the use effect of the ultrasonic transducer to a certain extent (for example, if the ultrasonic transducer is applied to the ultrasonic fingerprint module, it may interfere with the fingerprint image quality to a certain extent and affect the fingerprint recognition accuracy).

[0155] In the above optional implementation scheme of the present scheme, the angle between at least one outer side wall of the prepared top electrode 40 and the normal line of the substrate 10 is less than or equal to 45°, thereby avoiding the disadvantages of the multi-layer screen printing scheme in the related art, and effectively reducing the diffraction echo of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby reducing the interference to the prepared ultrasonic transducer 100 during use, and improving the use effect of the ultrasonic transducer 100. For example, if the ultrasonic transducer 100 is applied to an ultrasonic fingerprint module, since the angle between at least one outer side wall of the top electrode 40 and the normal line of the substrate 10 is less than or equal to 45°, the diffraction echo is reduced, thereby reducing the interference to the fingerprint image quality, and the fingerprint recognition accuracy can be effectively improved. In addition, the above range has low requirements on the preparation process, and it is relatively easy to form the top electrode 40, thereby reducing the difficulty of preparing the ultrasonic transducer.

[0156] Optionally, the normal line of the substrate 10 may be a straight line perpendicular to the upper surface of the substrate 10. Fig. 8A and Figure 8B See the schematic diagram for understanding.

[0157] In some optional embodiments, the angles between each outer side wall of the top electrode 40 obtained in the embodiment of the present application and the normal line of the substrate 10 are all less than or equal to 45°. This is to better reduce the diffraction echo of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby better reducing the interference to the prepared ultrasonic transducer 100 during use, and better improving the use effect of the ultrasonic transducer 100. In addition, the above range has low requirements on the preparation process, and it is relatively easy to form the top electrode 40, thereby reducing the difficulty of preparing the ultrasonic transducer.

[0158] Preferably, the angle between at least one outer side wall of the top electrode 40 obtained in the embodiment of the present application and the normal line of the substrate 10 is less than or equal to 5°. In this case, it can be basically considered that at least one outer side wall of the top electrode 40 is perpendicular to the substrate 10, which can better reduce the diffraction echo of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby reducing the interference to the prepared ultrasonic transducer 100 during use, and improving the use effect of the ultrasonic transducer 100.

[0159] Preferably, the angles between the outer side walls of the top electrode 40 obtained in the embodiment of the present application and the normal of the substrate 10 are all less than or equal to 5°. In this case, it can be basically considered that the outer side walls of the top electrode 40 are perpendicular to the substrate 10, so as to better reduce the diffraction echo of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby better reducing the interference to the prepared ultrasonic transducer 100 during use, and better improving the use effect of the ultrasonic transducer 100.

[0160] Preferably, an angle between at least one outer sidewall of the top electrode 40 and a normal line of the substrate 10 is equal to 0°.

[0161] Based on this, in the present application, the angle between at least one outer wall of the top electrode 40 and the normal of the substrate 10 is equal to 0°, which can better reduce the diffraction echo of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby better reducing the interference to the ultrasonic transducer 100 during use, and better improving the use effect of the ultrasonic transducer 100.

[0162] Preferably, the angles between the outer sidewalls of the top electrode 40 and the normal line of the substrate 10 are all equal to 0°.

[0163] It should be understood that the closer the angle between each outer side wall of the top electrode 40 and the normal line of the substrate 10 is to 0°, the closer the outer side wall and the substrate 10 are to being perpendicular, and the better the use effect of the ultrasonic transducer 100 is.

[0164] For example, see Fig. 8A The schematic diagram shown shows the angle between the outer sidewall of the top electrode 40 and the normal of the substrate 10, and both angles are θ, which is less than or equal to 45°. Preferably, the angle θ is less than or equal to 5°. Preferably, the angle θ is equal to 0°, that is, the outer sidewall of the top electrode 40 is perpendicular to the normal of the substrate 10.

[0165] For example, refer to Figure 8BThe schematic diagram shown shows the angle between the outer sidewall of the top electrode 40 and the normal of the substrate 10 in another example, and both angles are θ, and the angle θ is less than or equal to 45°. Preferably, the angle θ is less than or equal to 5°. Preferably, the angle θ is equal to 0°, that is, the outer sidewall of the top electrode 40 is perpendicular to the normal of the substrate 10.

[0166] It should be understood that the above figures are merely schematic diagrams for ease of understanding and are not intended to limit the embodiments of the present application.

[0167] The thickness of the top electrode 40 can be selected as required. Figure 2A and Figure 2B As shown, the thickness H of the top electrode 40 may refer to the distance between the upper surface of the top electrode 40 and the contact surface between the top electrode 40 and the upper surface of the piezoelectric layer 30. Optionally, the thickness H of the top electrode 40 is less than or equal to 60 um. The top electrode 40 in this thickness range will not be too thick, and can effectively meet the performance requirements of the ultrasonic transducer 100.

[0168] Preferably, the thickness of the top electrode 40 may be in the range of 10um to 40um. The top electrode 40 in this preferred thickness range will not be too thick or too thin, and can more effectively meet the performance requirements of the ultrasonic transducer 100. For example, within the range of 10um to 40um, the thickness of the top electrode may be 10um, 15um, 20um, 25um, 30um, 35um, 40um, etc., or may be other values.

[0169] Preferably, the thickness of the top electrode 40 may be in the range of 15 um to 40 um. The top electrode 40 in this preferred thickness range will not be too thick or too thin, and can more effectively meet the performance requirements of the ultrasonic transducer 100 .

[0170] In some optional embodiments, the elastic modulus of the material (e.g., metal material) used to form the top electrode 40 in step S104 of the present application is less than 130 GPa. The top electrode 40 is prepared by using the material (e.g., metal material) in the elastic modulus range of less than 130 GPa, which can adapt to the stress matching between the stacked materials of the ultrasonic transducer and achieve a smaller warping performance.

[0171] In some optional embodiments, the acoustic impedance of the material (eg, metal material) used to form the top electrode 40 in step S104 of the present application is less than 35 MRayl (ie, MPa·s / m 3, megapascal seconds per cubic meter). Since the material used to form the top electrode 40 needs to consider the acoustic impedance matching of the ultrasonic transducer laminated structure, a large acoustic impedance mismatch will lead to serious acoustic energy reflection, thereby resulting in inefficient transmission of ultrasonic waves. In layman's terms, when ultrasonic waves propagate in a laminated structure, if there is a large difference in the acoustic impedance of the dielectric material, the sound intensity of the ultrasonic wave will be significantly consumed during the propagation process. Therefore, by forming the top electrode 40 with the above-mentioned material (such as a metal material) with an acoustic impedance range of less than 35 MRayl, the acoustic impedance difference between the material of the substrate 10 (such as but not limited to silicon Si material, etc.), the material of the piezoelectric layer 30, etc. can be minimized as much as possible, thereby improving the performance of the top electrode 40 and improving the acoustic performance of the prepared ultrasonic transducer 100.

[0172] In some optional embodiments, the surface roughness of the top electrode 40 formed in step S104 of the present application can satisfy the average roughness Ra (Roughness Average) on the reference length is less than 0.8um, and the maximum roughness Rz on the reference length is less than 3um. Based on this, the top electrode 40 can effectively have a better appearance and a smaller thickness tolerance, a smoother surface, no obvious undulations, less granularity, and less obvious wrinkles or orange peel phenomenon, which is conducive to improving the performance of the prepared ultrasonic transducer 100.

[0173] In some optional embodiments, the preparation method of the embodiment of the present application also includes: forming an excitation electrode 60 that is not in contact with the bottom electrode 20 on the upper surface of the substrate 10; and subsequently obtaining a top electrode 40, which may be a top electrode 40 that is at least partially connected to the excitation electrode 60.

[0174] Based on this, by forming an excitation electrode 60 on the upper surface of the substrate 10, the subsequent steps can obtain a top electrode 40 that is at least partially connected to the excitation electrode 60, and the excitation electrode 60 can obtain an excitation signal, thereby effectively transmitting the excitation signal to the top electrode 40 connected thereto, so that the prepared ultrasonic transducer 100 can achieve the corresponding function.

[0175] In addition to obtaining the top electrode 40 at least partially connected to the excitation electrode 60, in some other optional embodiments, "obtaining the top electrode 40" in the present application may also include: obtaining the top electrode 40 directly connected to the external circuit. In this way, the top electrode 40 can also directly obtain the excitation signal from the external circuit. A suitable method can be selected as needed, and is not limited here.

[0176] In some optional embodiments, before the above step S104, the preparation method of the embodiment of the present application further includes: forming a pad area 90 for electrical connection with an external circuit on the upper surface of the substrate 10. The pad area 90 can be electrically connected to the excitation electrode 60 and the bottom electrode 20. By preparing the pad area 90 to be connected to the external circuit, the prepared ultrasonic transducer 100 can be connected to the external circuit to be used, so that the function of the ultrasonic transducer 100 can be effectively exerted.

[0177] In the ultrasonic transducer 100 prepared in the present application, the excitation electrode 60 is electrically connected to the pad area 90 and the top electrode 40, so as to obtain the excitation signal emitted by the external circuit through the pad area 90 and transmit it to the top electrode 40 to control the piezoelectric layer 30. Based on this, the excitation signal can be effectively transmitted to the top electrode 40 connected thereto through the excitation electrode 60, so that the ultrasonic transducer 100 can achieve the corresponding function.

[0178] Optionally, the external circuit may be a circuit in an external electronic device to which the ultrasonic transducer 100 is applied. The pad area 90 may be electrically connected to the external circuit.

[0179] Optionally, the pad area 90 may include a plurality of pads. Optionally, among the plurality of pads, a portion of the pads may be electrically connected to the top electrode 40, and a portion of the pads may be electrically connected to the bottom electrode 20. Optionally, other pads in the pad area 90 may be used for the extraction and access of other electrical signals. For example, a portion of the plurality of pads may be connected to the internal circuit of the ultrasonic transducer 100. Optionally, the pad area 90 may be formed on the upper surface of the substrate 10 by methods including, but not limited to, electroplating, etching after depositing a metal layer, physical vapor deposition, chemical vapor deposition, screen printing, and the like.

[0180] For example, a portion of the pads of the pad region 90 may be electrically connected to the excitation electrode 60 , thereby achieving electrical connection between the pad region 90 and the top electrode 40 through the excitation electrode 60 .

[0181] For example Figure 2C As shown, it shows Figure 2A The schematic plan view of the ultrasonic transducer 100 shown in FIG. 1 is a top view of the ultrasonic transducer 100, which schematically shows the pad area 90, including a plurality of pads 91. It should be understood that the above schematic views are not intended to limit the embodiments of the present application.

[0182] In some optional embodiments, the preparation method of the embodiment of the present application further includes: preparing a protective layer 70 covering at least a portion of the top electrode 40. Based on this, by preparing the protective layer 70 covering at least a portion of the top electrode 40, at least the top electrode 40 can be protected to at least ensure the performance of the top electrode 40, thereby improving the performance of the prepared ultrasonic transducer 100.

[0183] Optionally, the protective layer 70 can protect the various layers of the covered ultrasonic transducer 100, and can be an insulating layer that not only provides electrical insulation but also isolates the influence of external water, oxygen and other adverse environmental factors, thereby ensuring that the ultrasonic transducer 100 can work normally and effectively for a long time.

[0184] Optionally, “preparing a protective layer 70 covering at least a portion of the top electrode 40 ” in the present application may include: preparing a protective layer 70 covering at least a portion of the upper surface of the top electrode 40 .

[0185] Optionally, the term “preparing a protective layer 70 covering at least a portion of the top electrode 40” in the present application may include: preparing a protective layer 70 that completely covers the top electrode 40. For example, see Figure 2A and Figure 2B The ultrasonic transducer 100 prepared as shown is understood. Obviously, in this way, more comprehensive protection can be achieved for the top electrode 40, the performance of the top electrode 40 can be better guaranteed, and the ultrasonic transducer 100 can be effectively and normally operated for a long time.

[0186] Optionally, “preparing a protective layer 70 covering at least a portion of the top electrode 40” in the present application may include: preparing a protective layer 70 that completely covers the top electrode 40 and the piezoelectric layer 30. For example, see Figure 2A and Figure 2B Obviously, the protective layer 70 prepared in this way can provide more comprehensive protection for the top electrode 40 and the piezoelectric layer 30, better ensure the performance of the top electrode 40 and the piezoelectric layer 30, and ensure that the ultrasonic transducer 100 can work normally and effectively for a long time.

[0187] Optionally, the protective layer 70 may be prepared in any feasible manner, which is not limited herein. For example, it may be prepared by screen printing or exposure and development. Alternatively, it may be prepared by coating or dry film lamination. Optionally, when preparing the protective layer 70, avoid the protective layer 70 covering the pad area 90 to ensure that the pad area 90 can be exposed for subsequent electrical connection with an external circuit.

[0188] It should be understood that the above description is merely some optional embodiments of the preparation scheme of the embodiments of the present application, and is not any limitation to the embodiments of the present application.

[0189] In order to facilitate a further understanding of the preparation scheme of the ultrasonic transducer of the application embodiment, Figure 4A , Figure 4B , Figure 4C and Figure 4D The overall process of four optional preparation schemes is described.

[0190] <Optional Preparation Scheme 1>

[0191] Reference Figure 4A The process schematic diagram of the preparation scheme of the ultrasonic transducer is shown, and the process can be used to prepare Figure 2A The ultrasonic transducer 100 shown in the figure, the preparation scheme includes the following steps:

[0192] Step 1: forming a bottom electrode 20 on the upper surface of the substrate 10, and forming a piezoelectric layer 30 covering the bottom electrode 20 on the substrate 10, so as to obtain a substrate 10 having the bottom electrode 20 and the piezoelectric layer 30 formed on the upper surface, and further preparing an excitation electrode 60 and a pad area 90 on the substrate 10;

[0193] Step 2: forming a whole top electrode material layer 41 on the upper surface of the substrate 10 (for example, by spin coating or the like), so that the top electrode material layer 41 covers the piezoelectric layer 30;

[0194] Step 3: a first photomask 51 having at least one first light leakage region 512 and at least one first light shielding region 511 is disposed above the top electrode material layer 41, and a first exposure process is performed on the top electrode material layer 41 through the first photomask 51 using an exposure device, and appropriate exposure time and exposure energy are set, so that a second material layer portion of the top electrode material layer 41 below the first light leakage region 512 of the first photomask 51 is converted into a first chemical component due to the first exposure process, while a first material layer portion of the top electrode material layer 41 shielded below the first light shielding region 511 of the first photomask 51 is not converted into the first chemical component;

[0195] Step 4: dissolving the second material layer portion that has been converted into the first chemical composition by a first developing solution, and removing the dissolved second material layer portion by a cleaning process, leaving the first material layer portion to form a top electrode 40, and performing a baking process to better solidify the top electrode 40. When forming the top electrode 40, the outer sidewall of the formed top electrode 40 is made perpendicular to the substrate 10 as much as possible (that is, the angle between the outer sidewall of the top electrode 40 and the normal line of the substrate 10 is made as close to 0° as possible);

[0196] Step 5: Prepare a protective layer 70 covering the top electrode 40 and the piezoelectric layer 30 to protect the top electrode 40 and the piezoelectric layer 30 to obtain the ultrasonic transducer 100 .

[0197] It should be understood that Figure 4A In the example shown, 2 Figure 2A The ultrasonic transducer 100 in the embodiment of the present invention can be separated into two ultrasonic transducers 100. It should also be understood that Figure 2A , Figure 4A The examples shown are not intended to limit the embodiments of the present application.

[0198] <Optional Preparation Scheme 2>

[0199] Reference Figure 4B The process schematic diagram of the preparation scheme of the ultrasonic transducer is shown, and the process can be used to prepare Figure 2A The ultrasonic transducer 100 shown in the figure, the preparation scheme includes the following steps:

[0200] Step 1: forming a bottom electrode 20 on the upper surface of the substrate 10, and forming a piezoelectric layer 30 covering the bottom electrode 20 on the substrate 10, so as to obtain a substrate 10 having the bottom electrode 20 and the piezoelectric layer 30 formed on the upper surface, and further preparing an excitation electrode 60 and a pad area 90 on the substrate 10;

[0201] Step 2: forming a whole top electrode material layer 41 on the upper surface of the substrate 10 (e.g., by spin coating) so that the top electrode material layer 41 covers the piezoelectric layer 30, and then disposing a photoresist on the upper surface of the top electrode material layer 41, and curing the photoresist to form a barrier layer 80 covering the upper surface of the top electrode material layer (e.g., by spin coating);

[0202] Step 3: a second photomask 52 having at least one second light leakage region 522 and at least one second light shielding region 521 is placed above the barrier layer 80, and a second exposure process is performed on the barrier layer 80 through the second photomask 52 by using an exposure device, and appropriate exposure time and exposure energy are set, so that a second barrier layer portion 82 of the barrier layer 80 below the second light leakage region 522 of the second photomask 52 is converted into a second chemical component due to the second exposure process, while a first barrier layer portion 81 of the barrier layer 80 masked below the second light shielding region 521 of the second photomask 52 is not converted into the second chemical component;

[0203] Step 4: dissolving the second barrier layer portion 82 converted into the second chemical composition by a second developing solution, and removing the dissolved second barrier layer portion 82 by a cleaning process, so as to expose the second material layer portion of the top electrode material layer 41 and retain the first barrier layer portion 81;

[0204] Step 5: removing the second material layer portion by an etching process (dry etching or wet etching), and the first material layer portion below the first barrier layer portion 81 is prevented from being removed during the etching process and is retained to form a top electrode 40. When forming the top electrode 40, the outer sidewall of the formed top electrode 40 is made perpendicular to the substrate 10 as much as possible (that is, the angle between the outer sidewall of the top electrode 40 and the normal line of the substrate 10 is made as close to 0° as possible);

[0205] Step 6: Remove the first barrier layer 81 through a degumming process, and then perform a baking process after cleaning to better solidify the top electrode 40;

[0206] Step 7: Prepare a protective layer 70 covering the top electrode 40 and the piezoelectric layer 30 to protect the top electrode 40 and the piezoelectric layer 30 to obtain the ultrasonic transducer 100 .

[0207] It should be understood that Figure 4B In the example shown, 2 Figure 2A The ultrasonic transducer 100 in the embodiment of the present invention can be separated into two ultrasonic transducers 100. It should also be understood that Figure 2A , Figure 4B The examples shown are not intended to limit the embodiments of the present application.

[0208] <Optional Preparation Scheme 3>

[0209] Reference Figure 4C The process schematic diagram of the preparation scheme of the ultrasonic transducer is shown, and the process can be used to prepare Figure 2B The ultrasonic transducer 100 shown in the figure, the preparation scheme includes the following steps:

[0210] Step 1: forming a bottom electrode 20 on the upper surface of the substrate 10, and forming a piezoelectric layer 30 covering the bottom electrode 20 on the substrate 10, so as to obtain a substrate 10 having the bottom electrode 20 and the piezoelectric layer 30 formed on the upper surface, and further preparing an excitation electrode 60 and a pad area 90 on the substrate 10;

[0211] Step 2: forming a whole top electrode material layer 41 on the upper surface of the substrate 10 (for example, by spin coating or the like), so that the top electrode material layer 41 covers the piezoelectric layer 30;

[0212] Step 3: a third photomask 53 having at least one third light leakage region 532 and at least one third light shielding region 531 is disposed above the top electrode material layer 41, and a third exposure process is performed on the top electrode material layer 41 through the third photomask 53 using an exposure device, and appropriate exposure time and exposure energy are set, so that a first material layer portion of the top electrode material layer 41 below the third light leakage region 532 of the third photomask 53 is converted into a third chemical component due to the third exposure process, while a second material layer portion of the top electrode material layer 41 shielded below the third light shielding region 531 of the third photomask 53 is not converted into the third chemical component;

[0213] Step 4: dissolving the portion of the second material layer that has not been converted into the third chemical component by a third developing solution, and removing the dissolved portion of the second material layer by a cleaning process, retaining the portion of the first material layer that has been converted into the third chemical component to form a top electrode 40, and performing a baking process to better solidify the top electrode 40. When forming the top electrode 40, the outer sidewall of the formed top electrode 40 is made perpendicular to the substrate 10 as much as possible (that is, the angle between the outer sidewall of the top electrode 40 and the normal line of the substrate 10 is made as close to 0° as possible);

[0214] Step 5: Prepare a protective layer 70 covering the top electrode 40 and the piezoelectric layer 30 to protect the top electrode 40 and the piezoelectric layer 30 to obtain the ultrasonic transducer 100 .

[0215] It should be understood that Figure 4C In the example shown, 2 Figure 2B The ultrasonic transducer 100 in the embodiment of the present invention can be separated into two ultrasonic transducers 100. It should also be understood that Figure 2B , Figure 4C The examples shown are not intended to limit the embodiments of the present application.

[0216] <Optional Preparation Scheme 4>

[0217] Reference Figure 4D The process schematic diagram of the preparation scheme of the ultrasonic transducer is shown, and the process can be used to prepare Figure 2A The ultrasonic transducer 100 shown in the figure, the preparation scheme includes the following steps:

[0218] Step 1: forming a bottom electrode 20 on the upper surface of the substrate 10, and forming a piezoelectric layer 30 covering the bottom electrode 20 on the substrate 10, so as to obtain a substrate 10 having the bottom electrode 20 and the piezoelectric layer 30 formed on the upper surface, and further preparing an excitation electrode 60 and a pad area 90 on the substrate 10;

[0219] Step 2: forming a whole top electrode material layer 41 on the upper surface of the substrate 10 (e.g., by spin coating) so that the top electrode material layer 41 covers the piezoelectric layer 30, and then disposing a photoresist on the upper surface of the top electrode material layer 41, and curing the photoresist to form a barrier layer 80 covering the upper surface of the top electrode material layer (e.g., by spin coating);

[0220] Step 3: a fourth photomask 54 having at least one fourth light leakage region 542 and at least one fourth light shielding region 541 is placed above the barrier layer 80, and a fourth exposure process is performed on the barrier layer 80 through the fourth photomask 54 using an exposure device, and appropriate exposure time and exposure energy are set, so that a first barrier layer portion 81 of the barrier layer 80 below the fourth light leakage region 542 of the fourth photomask 54 is converted into a fourth chemical component due to the fourth exposure process, while a second barrier layer portion 82 of the barrier layer 80 masked below the fourth light shielding region 541 of the fourth photomask 54 is not converted into the fourth chemical component;

[0221] Step 4: dissolving the second barrier layer portion 82 that has not been converted into the fourth chemical component by a fourth developing solution, and removing the dissolved second barrier layer portion 82 by a cleaning process to expose the second material layer portion of the top electrode material layer 41, and retaining the first barrier layer portion 81 that has been converted into the fourth chemical component;

[0222] Step 5: removing the second material layer portion by an etching process (dry etching or wet etching), and preventing the first barrier layer portion 81 from being blocked, so that the first material layer portion below the first barrier layer portion 81 converted into the fourth chemical composition is avoided from being removed during the etching process and is retained to form the top electrode 40. When forming the top electrode 40, the outer sidewall of the formed top electrode 40 is made perpendicular to the substrate 10 as much as possible (that is, the angle between the outer sidewall of the top electrode 40 and the normal line of the substrate 10 is made as close to 0° as possible);

[0223] Step 6: Remove the first barrier layer portion 81 converted into the fourth chemical composition through a degumming process, and perform a baking treatment after cleaning to better solidify the top electrode 40;

[0224] Step 7: Prepare a protective layer 70 covering the top electrode 40 and the piezoelectric layer 30 to protect the top electrode 40 and the piezoelectric layer 30 to obtain the ultrasonic transducer 100 .

[0225] It should be understood that Figure 4D In the example shown, 2 Figure 2A The ultrasonic transducer 100 in the embodiment of the present invention can be separated into two ultrasonic transducers 100. It should also be understood that Figure 2A , Figure 4D The examples shown are not intended to limit the embodiments of the present application.

[0226] It should be understood that the above optional preparation scheme 1, optional preparation scheme 2, optional preparation scheme 3, and optional preparation scheme 4 are merely several optional examples of the embodiments of the present application, and they do not serve as any limitation to the embodiments of the present application. In addition, their introduction is relatively concise and can also be understood in conjunction with the relevant descriptions of the previous embodiments.

[0227] According to a second aspect of the embodiment of the present application, an ultrasonic transducer 100 is provided, which is prepared by any one of the preparation schemes of the ultrasonic transducer provided in the first aspect. Figure 2A and Figure 2B As shown, the ultrasonic transducer 100 comprises at least: a substrate 10, a bottom electrode 20, a piezoelectric layer 30 and a top electrode 40; the bottom electrode 20 is located on the upper surface of the substrate 10, the piezoelectric layer 30 is located on the upper surface of the substrate 10 and covers the bottom electrode 20, and at least a portion of the top electrode 40 is located above the piezoelectric layer 30; the top electrode 40 is used to be applied with an excitation signal to excite the piezoelectric layer 30 to emit an ultrasonic signal, and the bottom electrode 20 is used to receive an ultrasonic detection signal generated between the top electrode 40 and the bottom electrode 20 when the returned ultrasonic signal acts on the piezoelectric layer 30.

[0228] Since the ultrasonic transducer 100 of the second aspect is prepared by the preparation method of the first aspect, it can have better performance.

[0229] According to the third aspect of the embodiment of the present application, referring to Fig. 9 As shown, an ultrasonic fingerprint module 200 is provided, comprising: an ultrasonic transducer 100 as provided in the second aspect.

[0230] Since the ultrasonic fingerprint module 200 of the third aspect includes the ultrasonic transducer 100 of the second aspect, it has better performance and can better realize the ultrasonic fingerprint function.

[0231] According to the third aspect of the embodiment of the present application, referring to Fig. 10A , Fig. 10B As shown, an electronic device 300 is provided, comprising: the ultrasonic transducer 100 provided in the second aspect, or the ultrasonic fingerprint module 200 provided in the third aspect.

[0232] Optionally, the electronic device 300 may be any electronic device, including but not limited to a mobile phone, a computer, etc. It should be understood that the present application does not limit the configuration of the ultrasonic transducer 100 or the ultrasonic fingerprint module 200 in the electronic device 300 .

[0233] As an example, taking the electronic device 300 as a mobile phone and including the ultrasonic transducer 100 as an example, refer to Fig.11 As shown, the ultrasonic transducer 100 can be bonded to the bottom of the screen 320 of the electronic device 300 through the adhesive layer 310 for under-screen ultrasonic biometric detection. It should be understood that Fig.11 In Figure 2AThe optional ultrasonic transducer 100 is provided as an example for ease of understanding and is not intended to be a limitation to the present application. The same may be said for any other optional ultrasonic transducer of the embodiment and no additional examples will be given here for elaboration.

[0234] As another example, taking the electronic device 300 as a mobile phone and including the ultrasonic fingerprint module 200, the ultrasonic fingerprint module 200 can be bonded to the bottom of the mobile phone screen of the electronic device 300 through an adhesive layer to achieve under-screen ultrasonic fingerprint recognition.

[0235] It should be understood that the above is only an example application and does not constitute any limitation to the embodiments of the present application.

[0236] It can be understood that the above description of various aspects of the embodiments of the present application is merely some optional exemplary descriptions of the technical solutions of the embodiments of the present application, and does not constitute any limitation on the embodiments of the present application.

[0237] The optional implementation modes of the embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the embodiments of the present application are not limited thereto. It should be noted that, for the convenience of explaining the embodiments of the present application, the various drawings of the embodiments of the present application are not necessarily drawn according to the actual proportions, which are only used to facilitate the explanation of the technical solution and are not used for any restriction on the embodiments of the present application. Within the technical concept of the embodiments of the present application, the technical solutions of the embodiments of the present application can be subjected to a variety of simple modifications. The various technical features included in the various different embodiments of the embodiments of the present application can be combined in any suitable manner. In order to avoid unnecessary repetition, the embodiments of the present application will not be described separately for various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed in the embodiments of the present application, and all belong to the protection scope of the embodiments of the present application.

[0238] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments". It should be noted that the concepts of "first", "second", etc. mentioned in this application are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units. It should be noted that the modifications of "one" and "multiple" mentioned in this application are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0239] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing an ultrasonic transducer, comprising: forming a bottom electrode on the upper surface of the substrate, and forming a piezoelectric layer covering the bottom electrode above the substrate; forming a top electrode material layer covering the piezoelectric layer above the substrate; removing the second material layer portion of the top electrode material layer, and retaining the first material layer portion of the top electrode material layer that is predetermined to form the top electrode, wherein the second material layer portion is the other portion of the top electrode material layer except the first material layer portion; A top electrode is formed based on the remaining portion of the first material layer to obtain the ultrasonic transducer.

2. The method according to claim 1, wherein: An angle between at least one outer sidewall of the top electrode and a normal line of the substrate is less than or equal to 45°.

3. The method according to claim 2, wherein: An angle between at least one outer sidewall of the top electrode and a normal line of the substrate is less than or equal to 5°.

4. The method according to claim 1, wherein: The method further comprises: preparing a protection layer covering at least a portion of the top electrode.

5. The method according to any one of claims 1 to 4, wherein: The step of removing the second material layer portion of the top electrode material layer and retaining the first material layer portion of the top electrode material layer that is intended to form the top electrode comprises: A first photomask including at least one first light leakage region and at least one first light shielding region is arranged above the top electrode material layer to perform a first exposure process, so that a portion of the second material layer below the first light leakage region is converted into a first chemical component through the first exposure process, and a mask of the first light shielding region is used to prevent a portion of the first material layer below the first light shielding region from being converted into the first chemical component during the first exposure process; removing the portion of the second material layer that has been converted into the first chemical component, and retaining the portion of the first material layer; The forming of a top electrode based on the retained first material layer portion to obtain the ultrasonic transducer comprises: The retained portion of the first material layer is used as the top electrode to obtain the ultrasonic transducer.

6. The method according to claim 5, wherein: The step of partially removing the second material layer that has been converted into the first chemical component comprises: The second material layer portion that has been converted into the first chemical component is dissolved by a first developing solution, and the dissolved second material layer portion is removed.

7. The method according to claim 6, wherein: The step of partially removing the dissolved second material layer comprises: The top electrode material layer is cleaned to remove the dissolved portion of the second material layer.

8. The method according to any one of claims 1 to 4, wherein: The step of removing the second material layer portion of the top electrode material layer and retaining the first material layer portion of the top electrode material layer that is intended to form the top electrode comprises: A third photomask including at least one third light leakage region and at least one third light shielding region is arranged above the top electrode material layer to perform a third exposure process, wherein the first material layer portion below the third light leakage region is converted into a third chemical component through the third exposure process, and the second material layer portion below the third light shielding region is prevented from being converted into the third chemical component during the third exposure process through the mask of the third light shielding region; removing the portion of the second material layer that has not been converted into the third chemical component, and retaining the portion of the first material layer that has been converted into the third chemical component; The forming of a top electrode based on the retained first material layer portion to obtain the ultrasonic transducer comprises: The portion of the first material layer converted into the third chemical composition is retained as the top electrode to obtain the ultrasonic transducer.

9. The method according to claim 8, wherein: The step of removing the portion of the second material layer that has not been converted into the third chemical component comprises: The portion of the second material layer that has not been converted into the third chemical component is dissolved by a third developing solution, and the dissolved portion of the second material layer is removed.

10. The method according to claim 9, wherein: The step of partially removing the dissolved second material layer comprises: The top electrode material layer is cleaned to remove the dissolved portion of the second material layer.

11. The method according to any one of claims 1 to 4, wherein: The step of removing the second material layer portion of the top electrode material layer and retaining the first material layer portion of the top electrode material layer that is intended to form the top electrode comprises: forming a barrier layer covering the upper surface of the top electrode material layer; removing the second barrier layer portion of the barrier layer covering the second material layer portion to expose the second material layer portion, and retaining the first barrier layer portion of the barrier layer covering the first material layer portion; Removing the exposed second material layer portion by an etching process, and preventing the first material layer portion below the first barrier layer portion from being removed during the etching process by blocking the first barrier layer portion, so as to retain the first material layer portion; The forming of a top electrode based on the retained first material layer portion to obtain the ultrasonic transducer comprises: The retained portion of the first material layer is used as the top electrode to obtain the ultrasonic transducer.

12. The method according to claim 11, wherein: The step of removing the second barrier layer portion of the barrier layer covering the second material layer portion to expose the second material layer portion and retaining the first barrier layer portion of the barrier layer covering the first material layer portion comprises: A second photomask including at least one second light leakage region and at least one second light shielding region is arranged above the barrier layer for a second exposure process, so that a second barrier layer portion of the barrier layer below the second light leakage region is converted into a second chemical component through the second exposure process, and a mask of the second light shielding region is used to prevent a first barrier layer portion below the second light shielding region from being converted into the second chemical component during the second exposure process; The second barrier layer portion converted into the second chemical composition is removed to expose the second material layer portion, and the first barrier layer portion covering the first material layer portion is retained.

13. The method according to claim 12, wherein: The step of partially removing the second barrier layer that has been converted into a second chemical composition comprises: The second barrier layer portion converted into the second chemical composition is dissolved by a second developing solution, and the dissolved second barrier layer portion is removed.

14. The method according to claim 11, wherein: The forming of a barrier layer covering the upper surface of the top electrode material layer comprises: A photoresist is disposed to cover the upper surface of the top electrode material layer, and the photoresist is cured to form the blocking layer.

15. The method according to claim 11, wherein: The step of removing the second barrier layer portion of the barrier layer covering the second material layer portion to expose the second material layer portion and retaining the first barrier layer portion of the barrier layer covering the first material layer portion comprises: A fourth photomask including at least one fourth light leakage region and at least one fourth light shielding region is placed above the barrier layer to perform a fourth exposure process, wherein a first barrier layer portion of the barrier layer below the fourth light leakage region is converted into a fourth chemical component through the fourth exposure process, and a second barrier layer portion below the fourth light shielding region is prevented from being converted into the fourth chemical component during the fourth exposure process through the mask of the fourth light shielding region; The portion of the second barrier layer that has not been converted into the fourth chemical component is removed to expose the second material layer portion, and the portion of the first barrier layer that has been converted into the fourth chemical component remains.

16. The method according to claim 15, wherein: The part of the second barrier layer that is not converted into the fourth chemical composition is removed, comprising: The portion of the second barrier layer that has not been converted into the fourth chemical component is dissolved by a fourth developing solution, and the dissolved portion of the second barrier layer is removed.

17. The method according to any one of claims 1 to 4, wherein: After forming the piezoelectric layer, the implementation temperature of the preparation method is controlled below 135°C.

18. The method according to any one of claims 1 to 4, wherein: The material used to prepare the top electrode material layer includes at least one of a silver paste and a PEDOT-based conductive ink material.

19. An ultrasonic transducer, prepared by the method for preparing an ultrasonic transducer according to any one of claims 1 to 18, the ultrasonic transducer comprising: substrate, bottom electrode, piezoelectric layer and top electrode; The bottom electrode is located on the upper surface of the substrate, the piezoelectric layer is located above the substrate and covers the bottom electrode, and at least a portion of the top electrode is located above the piezoelectric layer; The top electrode is used to be applied with an excitation signal to excite the piezoelectric layer to emit an ultrasonic signal, and the bottom electrode is used to receive an ultrasonic detection signal generated between the top electrode and the bottom electrode when the returned ultrasonic signal acts on the piezoelectric layer.

20. An ultrasonic fingerprint module, comprising: The ultrasonic transducer as claimed in claim 19.

21. An electronic device, comprising: The ultrasonic transducer as claimed in claim 19, or the ultrasonic fingerprint module as claimed in claim 20.

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