Ultrasonic transducer, ultrasonic fingerprint module and electronic equipment

Abstract

The embodiment of the utility model provides an ultrasonic transducer, an ultrasonic fingerprint module and electronic equipment. 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 part of the top electrode is located above the piezoelectric layer; the included angle between at least one outer side wall of the top electrode and the normal of the substrate is smaller than or equal to 45 degrees. The performance of the ultrasonic transducer in the scheme is good.

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, an ultrasonic fingerprint module, and an electronic device. Background Art

[0002] Ultrasonic transducers utilize the mechanical-electrical conversion properties of piezoelectric materials. On the one hand, they can be stimulated by the voltage output of the driving circuit to emit ultrasonic signals. On the other hand, they can convert ultrasonic signals reflected from the outside world into electrical signals, thereby obtaining information about the external sensing surface. These transducers can be widely used in fields including, but not limited to, biometric identification (for example, an example application can be an ultrasonic fingerprint module that can capture fingerprint images for fingerprint recognition). Existing ultrasonic transducers have problems such as poor performance. Therefore, it is necessary to provide some new technical solutions for ultrasonic transducers to improve their performance. Utility Model Content

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

[0004] According to a first aspect of an embodiment of the present application, an ultrasonic transducer is provided, comprising: 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 on the upper surface of the substrate and covers the bottom electrode, and at least a portion of the top electrode is located above the piezoelectric layer; wherein, an angle between at least one outer side wall of the top electrode and a normal to the substrate is less than or equal to 45°.

[0005] In some optional embodiments, an angle between at least one outer sidewall of the top electrode and a normal to the substrate is less than or equal to 5°.

[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 equal to 0°.

[0007] In some optional embodiments, the connection between the outer sidewall of the top electrode and the upper surface of the top electrode is arc-shaped.

[0008] In some optional embodiments, the ultrasonic transducer further includes a pad area, which is disposed on the substrate and electrically connected to the bottom electrode; the pad area is electrically connected to the top electrode; and the pad area is also used to connect to an external circuit.

[0009] In some optional embodiments, the ultrasonic transducer further includes: an excitation electrode, which is arranged on the upper surface of the substrate and does not contact the bottom electrode, the top electrode is electrically connected to the excitation electrode, and the excitation electrode is electrically connected to the pad area.

[0010] In some optional embodiments, the ultrasonic transducer further includes: a protective layer, wherein the protective layer at least covers the upper surface of the top electrode to protect at least a portion of the top electrode.

[0011] In some optional embodiments, the ultrasonic transducer also includes a seed metal layer, which is located between the piezoelectric layer and the top electrode, and the thickness of the seed metal layer is less than the thickness of the top electrode; the top electrode is an electroplated metal layer formed on the upper surface of the seed metal layer; the thickness of the seed metal layer is less than or equal to 2um; the thickness of the top electrode ranges from 10um to 40um; the top electrode is a single metal layer, a multi-layer metal stack or an alloy layer.

[0012] In some optional embodiments, the top electrode is at least one of a pure tin layer, a pure copper layer, a pure nickel layer, a pure gold layer, a pure silver layer, a pure indium layer, a pure chromium layer, a pure zinc layer, a pure titanium layer, and a pure lead layer; or, the top electrode is an alloy layer of at least two of pure tin, pure copper, pure nickel, pure gold, pure silver, pure indium, pure chromium, pure zinc, pure titanium, and pure lead.

[0013] In some optional embodiments, the seed metal layer includes a first metal layer and a second metal layer, and the first metal layer is located between the piezoelectric layer and the second metal layer, and the second metal layer is located between the first metal layer and the top electrode; wherein the resistivity of the first metal layer is higher than the resistivity of the second metal layer; the thickness of the first metal layer is less than or equal to 1um, and the thickness of the second metal layer is less than 2um; the first metal layer is at least one of a titanium layer, a titanium-tungsten alloy layer, and a chromium layer, and / or the second metal layer is at least one of a copper layer, a gold layer, and a nickel-vanadium alloy layer.

[0014] In some optional embodiments, the ultrasonic transducer further includes: a second enclosure structure, the second enclosure structure is located on the upper surface of the substrate, and the second enclosure structure surrounds at least a portion of the piezoelectric layer; at least a portion of the seed metal layer is arranged between at least a portion of the top electrode and the second enclosure structure, and the piezoelectric layer is coated between the seed metal layer and the second enclosure structure; at least a portion of the piezoelectric layer covers at least a portion of the upper surface of the second enclosure structure, or at least a portion of the second enclosure structure covers at least a portion of the upper surface of the piezoelectric layer.

[0015] In some optional embodiments, the ultrasonic transducer further includes: a first enclosure structure, the first enclosure structure forming a accommodating space, the top electrode being located in the accommodating space, and the outer side wall of the top electrode being in contact with the inner side wall of the first enclosure structure; the thickness of the first enclosure structure being greater than or equal to the thickness of the top electrode.

[0016] In some optional embodiments, an angle between at least one inner sidewall of the first enclosure structure and a normal to the substrate is less than or equal to 45°.

[0017] In some optional embodiments, an angle between at least one inner sidewall of the first enclosure structure and a normal to the substrate is less than or equal to 5°.

[0018] In some optional embodiments, an angle between at least one inner sidewall of the first enclosure structure and a normal to the substrate is equal to 0°.

[0019] In some optional embodiments, the first enclosure structure is a cured photoresist enclosure structure; the first enclosure structure at least partially covers the outer wall of the piezoelectric layer, and / or the first enclosure structure is at least partially located in the edge area of ​​the upper surface of the piezoelectric layer.

[0020] In some optional embodiments, the ultrasonic transducer further includes: a second enclosure structure, the second enclosure structure being located on the upper surface of the substrate, the second enclosure structure surrounding at least a portion of the piezoelectric layer; the piezoelectric layer being coated between the top electrode and the second enclosure structure; the second enclosure structure being a cured photoresist enclosure structure; the piezoelectric layer at least partially covering the upper surface of the second enclosure structure, or the second enclosure structure partially covering the upper surface of the piezoelectric layer.

[0021] In some optional embodiments, the ultrasonic transducer further includes a second enclosure structure, which is located on the upper surface of the substrate and surrounds at least a portion of the piezoelectric layer; the top electrode is at least partially in contact with the second enclosure structure, and the piezoelectric layer is enclosed between the top electrode and the second enclosure structure; and the first enclosure structure is at least partially located on the upper surface of the second enclosure structure; and there is a gap between the first enclosure structure formed on the upper surface of the second enclosure structure and the piezoelectric layer.

[0022] In some optional embodiments, the second enclosure structure is a cured photoresist enclosure structure; the piezoelectric layer at least partially covers the upper surface of the second enclosure structure, or the second enclosure structure partially covers the upper surface of the piezoelectric layer.

[0023] In some optional embodiments, the top electrode satisfies at least one of the following conditions: the elastic modulus of the top electrode is less than 130 GPa; the acoustic impedance of the top electrode is less than 35 MRayl; the average roughness Ra of the surface of the top electrode is less than 0.8 um; the maximum roughness Rz of the surface of the top electrode is less than 3 um; the top electrode is at least one of a tin layer, a copper layer, a nickel layer, a gold layer, a silver layer, an indium layer, a chromium layer, a zinc layer, a titanium layer, and a lead layer, or the top electrode is an alloy layer of at least two of tin, copper, nickel, gold, silver, indium, chromium, zinc, titanium, and lead.

[0024] According to a second aspect of the embodiments of the present application, an ultrasonic fingerprint module is provided, comprising: the ultrasonic transducer provided in the first aspect above.

[0025] According to the third aspect of the embodiment of the present application, an electronic device is provided, comprising the ultrasonic fingerprint module, screen, back panel and side frame provided in the second aspect above, wherein the ultrasonic fingerprint module is affixed to the lower surface of the screen or to the inner side of the back panel or to the inner side of the side frame.

[0026] The ultrasonic transducer in the embodiment of the present application, since the angle between at least one outer wall of its top electrode and the normal of the substrate is less than or equal to 45°, can effectively reduce the diffraction echo of the ultrasonic signal caused by the boundary morphology of the top electrode compared to the ultrasonic transducer in the related art in which the outer wall of the top electrode has a gently sloping morphology, thereby reducing the interference to the use of the ultrasonic transducer, improving the use effect of the ultrasonic transducer, and effectively improving the performance of the ultrasonic transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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.

[0028] Figure 1A A schematic diagram showing an ultrasonic transducer according to an example of the present application is shown.

[0029] Figure 1B Shown Figure 1A A schematic plan view of the ultrasonic transducer shown in FIG.

[0030] Figure 2A A schematic diagram showing another example of an ultrasonic transducer in the present application is shown.

[0031] Figure 2B Shown Figure 2AA schematic plan view of the ultrasonic transducer shown in FIG.

[0032] Figure 3 A schematic diagram of an ultrasonic transducer according to another example of the present application is shown.

[0033] Figure 4 A schematic diagram of an ultrasonic transducer according to another example of the present application is shown.

[0034] Figure 5A A schematic diagram of an ultrasonic transducer according to another example of the present application is shown.

[0035] Figure 5B Shown Figure 5A A schematic plan view of the ultrasonic transducer shown in FIG.

[0036] Figure 6A A schematic diagram of an ultrasonic transducer according to another example of the present application is shown.

[0037] Figure 6B Shown Figure 6A A schematic plan view of the ultrasonic transducer shown in FIG.

[0038] Figure 7 A schematic diagram of an ultrasonic transducer according to another example of the present application is shown.

[0039] Figure 8 A schematic diagram of an ultrasonic transducer according to another example of the present application is shown.

[0040] Figure 9A 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.

[0041] Figure 9B A schematic diagram showing the angle between the outer sidewall of the top electrode and the normal line of the substrate in another example of the present application is shown.

[0042] Figure 9C A schematic diagram showing the angle between the outer sidewall of the top electrode and the normal line of the substrate in yet another example of the present application is shown.

[0043] Figure 9D A schematic diagram showing the angle between the outer sidewall of the top electrode and the normal line of the substrate in yet another example of the present application is shown.

[0044] Figure 10 A schematic diagram of an exemplary seed metal layer in the present application is shown.

[0045] Figure 11 A schematic block diagram of an ultrasonic fingerprint module according to an example of the present application is shown.

[0046] Figure 12A A schematic block diagram of an exemplary electronic device in the present application is shown.

[0047] Figure 12B A schematic block diagram of another example electronic device in the present application is shown.

[0048] Figure 13 A schematic diagram showing an example of an ultrasonic transducer bonded under the screen of an electronic device in the present application is shown.

[0049] Description of reference numerals:

[0050] 100. Ultrasonic transducer; 10. Substrate; 20. Bottom electrode; 30. Piezoelectric layer; 40. Top electrode; 50. Seed metal layer; 51. First metal layer; 52. Second metal layer; 60. Excitation electrode; 70. Protective layer; 81. First enclosure structure; 82. Second enclosure structure; 90. Pad area; 91. Pad; 200. Ultrasonic fingerprint module; 300. Electronic device; 310. Adhesive layer; 320. Screen. DETAILED DESCRIPTION

[0051] 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. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present application.

[0052] Ultrasonic transducers utilize the mechanical-electrical conversion characteristics of piezoelectric materials. On the one hand, they can be stimulated by the voltage output by the driving circuit to emit ultrasonic signals to the outside world. On the other hand, they can 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 recognition (for example, an example application can be used in ultrasonic fingerprint modules to collect fingerprint information for fingerprint recognition). For example, ultrasonic transducers are applied to ultrasonic fingerprint modules and set in specific areas of the screens of electronic devices such as but not limited to smartphones. They can be used for fingerprint recognition and can obtain the peak and trough distribution information of the fingerprint. By using the difference in the strength of the reflected ultrasonic signals corresponding to the peaks and troughs, signal processing is performed to obtain the fingerprint image and realize user identity authentication. The advantage of fingerprint recognition systems based on ultrasonic transducer sensing technology is that they are 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 product's anti-interference and safety. In some examples of ultrasonic transducer structures, there is a circuit structure for emitting ultrasonic excitation signals and processing ultrasonic echo signals, as well as a piezoelectric material layer with a high piezoelectric coefficient, that is, it is generally composed of a bottom electrode, a piezoelectric layer, and a top electrode. Some types of ultrasonic transducers in the related art often use multi-layer silk screen printing to prepare the top electrode. 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 an ultrasonic fingerprint module, it may interfere with the fingerprint image quality to a certain extent and affect the fingerprint recognition accuracy). The ultrasonic transducers in the prior art have problems such as poor performance. Therefore, it is necessary to provide some new technical solutions to improve the performance of the ultrasonic transducer.

[0053] The following describes the specific implementation of the technical solution of the embodiment of the present application in conjunction with the accompanying drawings. It should be noted that for the sake of convenience, the various structures in the various drawings are not necessarily drawn according to the actual scale. The various drawings do not constitute any limitation on the embodiments of the present application.

[0054] Reference Figure 1A 、 Figure 2A 、 Figure 3 、 Figure 4 、 Figure 5A 、 Figure 6A 、 Figure 7 and Figure 8As shown, according to the first aspect of an embodiment of the present application, an ultrasonic transducer 100 is provided, which includes: 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; wherein, at least one outer side wall of the top electrode 40 has an angle less than or equal to 45° with the normal of the substrate 10.

[0055] Based on this, the ultrasonic transducer 100, because the angle between at least one outer sidewall of its top electrode and the normal of the substrate 10 is less than or equal to 45°, can effectively reduce the diffraction echo of the ultrasonic signal caused by the boundary morphology of the top electrode, compared to ultrasonic transducers in the related art with gently sloping outer sides of the top electrode, thereby reducing the interference caused by this during use of the ultrasonic transducer, improving the use effect of the ultrasonic transducer, and effectively improving the performance of the ultrasonic transducer. In addition, the above angle range has low requirements for the manufacturing process, making it easier to form the top electrode 40, thereby reducing the difficulty of manufacturing the ultrasonic transducer.

[0056] For example, if the ultrasonic transducer 100 is applied to an ultrasonic fingerprint module, since the angle between at least one outer wall of the top electrode 40 and the normal of the substrate 10 is less than or equal to 45°, the diffraction echo is reduced, thereby reducing the interference with the fingerprint image quality, and effectively improving the accuracy of fingerprint recognition.

[0057] Optionally, in the present application, the substrate 10 may be a silicon-based substrate or a TFT (Thin Film Transistor) substrate, or other types of substrates if required.

[0058] Alternatively, 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. The PVDF material may include PVDF, PVDF copolymer, etc.

[0059] Both the bottom electrode 20 and the top electrode 40 can be conductive. Optionally, the top electrode 40 can be used to apply an excitation signal to excite the piezoelectric layer 30 to emit an ultrasonic signal, and the bottom electrode 20 can be used to receive an ultrasonic detection signal generated between the top electrode 40 and the bottom electrode 20 when the returning ultrasonic signal acts on the piezoelectric layer 30.

[0060] 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.

[0061] Alternatively, the normal line of the substrate 10 may be a straight line perpendicular to the upper surface of the substrate 10. Figure 9A 、 Figure 9B 、 Figure 9C and Figure 9D See the schematic diagram for understanding.

[0062] In some optional embodiments, the angle between each outer sidewall of the top electrode 40 and the normal to the substrate 10 is less than or equal to 45°. This can effectively reduce the diffraction echoes of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby further reducing the interference caused by the top sidewalls during operation of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100. Furthermore, the above range has low requirements for the manufacturing process, making it easier to form the top electrode 40, thereby reducing the difficulty of manufacturing the ultrasonic transducer.

[0063] Preferably, the angle between at least one outer sidewall of the top electrode 40 and the normal of the substrate 10 in the embodiment of the present application is less than or equal to 5°. In this case, it can be basically considered that at least one outer sidewall 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 caused by the echo during use of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100.

[0064] Preferably, the angles between the outer sidewalls of the top electrode 40 obtained in the embodiment of the present application and the normal to the substrate 10 are all less than or equal to 5°. In this case, it can be basically considered that the outer sidewalls of the top electrode 40 are perpendicular to the substrate 10, thereby better reducing the diffraction echoes of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby better reducing the interference caused by the echoes during the use of the ultrasonic transducer 100, and better improving the use effect of the ultrasonic transducer 100.

[0065] Preferably, an angle between at least one outer sidewall of the top electrode 40 and the normal line of the substrate 10 is equal to 0°.

[0066] 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.

[0067] 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°.

[0068] 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 performance of the ultrasonic transducer 100 is.

[0069] In some optional embodiments, the connection between the outer sidewall of the top electrode 40 and the upper surface of the top electrode 40 is arc-shaped.

[0070] Based on this, in this application, the arc design of the connection between the outer wall of the top electrode 40 and the upper surface of the top electrode 40 makes the reflection performance of the ultrasonic signal when passing through the connection between the outer wall of the top electrode 40 and the upper surface of the top electrode 40 relatively consistent, without too much reflection in some places and too little reflection in other places, which is beneficial to improving the performance of the ultrasonic transducer 100.

[0071] In some optional embodiments, referring to Figure 1A 、 Figure 2A 、 Figure 3 、 Figure 4 、 Figure 5A 、 Figure 6A 、 Figure 7 and Figure 8 As shown, the ultrasonic transducer 100 further includes a pad area 90, which is disposed on the substrate 10 and can be electrically connected to the bottom electrode 20. Optionally, the pad area 90 can also be connected to the top electrode 40. The pad area 90 is also used to connect to an external circuit.

[0072] The pad area 90 is connected to an external circuit and can transmit an excitation signal input from the external circuit to the top electrode 40. In this application, by providing the pad area 90, it is convenient for the ultrasonic transducer 100 to be connected to the external circuit required, thereby effectively exerting the function of the ultrasonic transducer 100.

[0073] Alternatively, the external circuit may be a circuit in an electronic device to which the ultrasonic transducer 100 is applied. The pad area 90 may be electrically connected to the external circuit.

[0074] Optionally, the pad area 90 may include multiple pads. Optionally, some of the multiple pads may be electrically connected to the top electrode 40, and some may be electrically connected to the bottom electrode 20. Optionally, other pads in the pad area 90 may be used for routing and receiving other electrical signals. For example, some of the multiple pads may be connected to the internal circuitry of the ultrasonic transducer 100. Optionally, when connecting the pad area 90 to the external circuitry, any electrical connection method may be used, including but not limited to welding, conductive adhesive bonding, and the like.

[0075] For example Figure 1B As shown, it shows Figure 1AFIG. 1 is a schematic plan view of an ultrasonic transducer 100 as shown in FIG. 1 , which schematically shows a pad area 90 including a plurality of pads 91 (it should be understood that Figure 1B Omitted Figure 1A The protective layer 70 in FIG. 1 ). For example Figure 2B As shown, it shows Figure 2A FIG. 1 is a schematic plan view of an ultrasonic transducer 100 as shown in FIG. 1 , which schematically shows a pad area 90 including a plurality of pads 91 (it should be understood that Figure 2B Omitted Figure 2A The protective layer 70 in FIG. 1 ). For example Figure 5B As shown, it shows Figure 5A FIG. 1 is a schematic plan view of an ultrasonic transducer 100 as shown in FIG. 1 , which schematically shows a pad area 90 including a plurality of pads 91 (it should be understood that Figure 5B Omitted Figure 5A For example, the protective layer 70 Figure 6B As shown, it shows Figure 6A 1 is a plan view of an ultrasonic transducer 100 as exemplified in FIG, which schematically illustrates a 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.

[0076] In some optional embodiments, referring to Figure 1A 、 Figure 2A 、 Figure 3 、 Figure 4 、 Figure 5A 、 Figure 6A 、 Figure 7 and Figure 8 As shown, the ultrasonic transducer 100 further includes an excitation electrode 60 , which is disposed on the upper surface of the substrate 10 and does not contact the bottom electrode 20 , the top electrode 40 is electrically connected to the excitation electrode 60 , and the excitation electrode 60 is electrically connected to the pad area 90 .

[0077] 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 an excitation signal from an 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.

[0078] For example, a portion of the pads in 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 .

[0079] Alternatively, in addition to being connected to the excitation electrode 60, in some other optional embodiments, the top electrode 40 may also be directly connected to an external circuit. In this way, the top electrode 40 may also directly receive an excitation signal from the external circuit. This method may be selected as needed and is not limited herein.

[0080] In some optional embodiments, referring to Figure 1A 、 Figure 2A 、 Figure 3 、 Figure 4 、 Figure 5A 、 Figure 6A 、 Figure 7 and Figure 8 As shown, the ultrasonic transducer 100 further includes a protective layer 70 , which covers at least the upper surface of the top electrode 40 to protect at least a portion of the top electrode 40 .

[0081] Based on this, by at least covering the upper surface of the top electrode 40 with the protection layer 70 , at least a portion of the top electrode 40 can be protected to at least ensure the performance of the top electrode 40 and improve the performance of the ultrasonic transducer 100 .

[0082] Optionally, the protective layer 70 can protect the various layers of the covered ultrasonic transducer 100. It 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, ensuring that the ultrasonic transducer 100 can work normally and effectively for a long time.

[0083] Optionally, refer to Figure 1A 、 Figure 2A 、 Figure 3 、 Figure 6A As shown, the protective layer 70 completely covers the top electrode 40. Obviously, this can achieve more comprehensive protection for the top electrode 40, better ensure the performance of the top electrode 40, improve the performance of the ultrasonic transducer 100, and ensure that the ultrasonic transducer 100 can work normally and effectively for a long time.

[0084] Optionally, refer to Figure 1A 、 Figure 2A As shown in FIG6 , the protective layer 70 covers the top electrode 40 and the piezoelectric layer 30. 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, improve the performance of the ultrasonic transducer 100, and ensure that the ultrasonic transducer 100 can operate normally and effectively for a long time.

[0085] It should be understood that the shape of the protective layer 70 can be arbitrarily set according to requirements. Figure 1A 、 Figure 2A 、 Figure 3 、 Figure 4 、 Figure 5A 、 Figure 6A 、 Figure 7 and Figure 8 Only some exemplary styles of the protective layer 70 are shown, among which some are substantially the same and some are different, but none of them shall be construed as any limitation to the embodiments of the present application.

[0086] Optionally, the top electrode 40 in the present application may be an electroplated metal layer. That is, the top electrode 40 may be a top electrode formed by electroplating. The electroplated metal layer top electrode 40 in the present application has a simple and easy-to-control process during preparation, has a small thickness tolerance, and has better quality stability, which can effectively improve the performance of the ultrasonic transducer. Compared with other forms of top electrodes, its preparation process difficulty and time cycle are lower, and it is less prone to production anomalies, thereby resulting in a higher product yield of the ultrasonic transducer.

[0087] Furthermore, because the top electrode 40, in the form of an electroplated metal layer, is formed based on the principle of electrolysis, metal cations accept electrons on the electroplating cathode (electroplating substrate) and are reduced to metal atoms, depositing to form a dense metal coating. The resulting metal coating (i.e., the top electrode 40) is dense and free of delamination, voids, resin agglomerations, and other abnormalities. Therefore, the top electrode 40 exhibits superior performance, which is beneficial for improving the performance of the ultrasonic transducer 100.

[0088] Optionally, the connection between the outer sidewall of the top electrode 40 and the upper surface of the top electrode 40 is arc-shaped, which may be formed by electroplating. In other words, the arc-shaped connection may be a special shape feature of the top electrode 40 in the form of an electroplated metal layer, which may have a good beneficial effect.

[0089] Alternatively, the top electrode 40 may be an electroplated metal layer formed on the upper surface of the seed metal layer 50. In some alternative embodiments, referring to Figure 1A 、 Figure 2A 、 Figure 3 As shown, the ultrasonic transducer 100 further includes a seed metal layer 50 . The seed metal layer 50 is located between the piezoelectric layer 30 and the top electrode 40 . The thickness of the seed metal layer 50 is less than that of the top electrode 40 .

[0090] In this application, the seed metal layer 50 can serve as a cathode for electroplating (i.e., an electroplating substrate). For example, when preparing the ultrasonic transducer 100, the seed metal layer 50 can be prepared first, and then electroplated on the upper surface of the seed metal layer 50 to obtain a top electrode 40 with better performance.

[0091] It should be understood that in the present application, the seed metal layer 50 can facilitate the formation of the top electrode 40 in the form of an electroplated metal layer, thereby obtaining a top electrode 40 with better performance, thereby improving the performance of the ultrasonic transducer 100. In addition, the ultrasonic transducer provided by this solution has a simple structure, and therefore, the manufacturing process is simple and the cost is low.

[0092] The thickness of the seed metal layer 50 is not specifically limited in this application and can be selected as needed. In some optional embodiments, the thickness of the seed metal layer 50 is less than or equal to 2 μm. Within this thickness range, the seed metal layer 50 is neither too thin nor too thick, and has good step coverage over the undulating topography of the substrate, effectively meeting electroplating requirements and ensuring the performance of the top electrode 40 in the form of an electroplated metal layer.

[0093] The present application does not specifically limit the type of metal material of the seed metal layer 50. Any metal material can be used as needed.

[0094] Alternatively, the seed metal layer 50 may be a single metal layer. Alternatively, the seed metal layer 50 may be a multi-layer metal layer. This can be configured as required and is not limited herein.

[0095] In some optional embodiments, the seed metal layer 50 is a double-layer metal. Figure 10 As shown in the schematic diagram, the seed metal layer 50 includes a first metal layer 51 and a second metal layer 52, wherein the first metal layer 51 is located between the piezoelectric layer 30 and the second metal layer 52, and the second metal layer 52 is located between the first metal layer 51 and the top electrode 40. Optionally, the resistivity of the first metal layer 51 is higher than the resistivity of the second metal layer 52.

[0096] The first metal layer 51 and the second metal layer 52 can be made of any feasible metal layer. For example, the first metal layer 51 can be made of titanium, titanium-tungsten alloy, or chromium, that is, the first metal layer 51 can be at least one of a titanium layer, a titanium-tungsten alloy layer, and a chromium layer. For example, the second metal layer 52 can be made of copper, gold, or a nickel-vanadium alloy, that is, the second metal layer 52 can be at least one of a copper layer, a gold layer, and a nickel-vanadium alloy layer. When making the seed metal layer 50, the first metal layer 51 can be first formed on at least the upper surface of the piezoelectric layer 30, and then the second metal layer 52 can be formed on the first metal layer 51. When forming the top electrode 40, it can be formed on the second metal layer 52, so that the first metal layer 51 is located between the piezoelectric layer 30 and the second metal layer 52, and the second metal layer 52 is located between the first metal layer 51 and the top electrode 40.

[0097] In the present application, the benefit of using a double-layer metal layer for the seed metal layer 50 is: taking the first metal layer 51 as a titanium layer or a titanium-tungsten alloy layer and the second metal layer 52 as a copper layer as an example, the second metal layer 52 (such as a copper layer, a gold layer or a nickel-vanadium alloy layer) has a lower resistivity and better conductivity, so when the top electrode 40 in the form of an electroplated metal layer is formed on the second metal layer 52, the effect is better, which is also beneficial to the stability of the electroplating process, and the performance of the top electrode 40 in the form of an electroplated metal layer is also better; and the first metal layer 51 (such as a titanium layer, a titanium-tungsten alloy layer or a chromium layer) can improve the second metal layer 52 and the package The adhesion between the upper surface of the substrate 10 including the piezoelectric layer 30 can be improved, thereby improving the quality of the generated seed metal layer 50, and can serve as a barrier layer to prevent the metal material of the second metal layer 52 from diffusing downward into the underlying material (such as the piezoelectric layer 30), and the first metal layer 51 can stably serve as the crystal nucleus for the growth of the second metal layer 52, promote the uniform deposition of the second metal layer 52, and further improve the quality of the seed metal layer 50, so that the top electrode 40 in the form of an electroplated metal layer formed on the seed metal layer 50 has better performance, which can effectively improve the performance of the ultrasonic transducer 100.

[0098] Optionally, the thickness of the first metal layer 51 is less than or equal to 1 μm, and the thickness of the second metal layer 52 is less than 2 μm. The first metal layer 51 and the second metal layer 52 within this thickness range are neither too thin nor too thick, and have good step coverage on the undulating topography of the substrate, which can effectively meet electroplating requirements and ensure the performance of the top electrode 40 in the form of an electroplated metal layer.

[0099] Optionally, the sum of the thicknesses of the first metal layer 51 and the second metal layer 52 may be less than or equal to 2 μm, so as to meet the requirement that the thickness of the seed metal layer 50 is less than 2 μm in the aforementioned optional embodiment.

[0100] Optionally, the thickness of the first metal layer 51 can be smaller than the thickness of the second metal layer 52, so that the first metal layer 51 can meet the requirement of blocking the metal material of the second metal layer 52 from diffusing downward to the underlying material, and the second metal layer 52 can also meet the thickness uniformity requirement when electroplating the top electrode 40.

[0101] In some optional embodiments, referring to Figure 4 、 Figure 5A 、 Figure 7 and Figure 8 As shown, the ultrasonic transducer 100 also includes: a first enclosure structure 81, the first enclosure structure 81 forms an accommodating space, the top electrode 40 is located in the accommodating space, and the outer wall of the top electrode 40 is in contact with the inner wall of the first enclosure structure 81; the thickness of the first enclosure structure 81 is greater than or equal to the thickness of the top electrode 40.

[0102] Based on this, on the one hand, in the preparation process of some optional ultrasonic transducers 100, the first enclosure structure 81 can be prepared before the top electrode 40, and a holding space is formed by the first enclosure structure 81. The top electrode 40 is located in the holding space, and the outer wall of the top electrode 40 is in contact with the inner wall of the first enclosure structure 81, which can reduce the position error of the top electrode 40, thereby improving the quality stability of the top electrode 40 and improving the performance of the ultrasonic transducer 100; on the other hand, the first enclosure structure 81 can also be used at least to protect the top electrode 40 to ensure the performance of the top electrode 40 and improve the performance of the ultrasonic transducer 100.

[0103] Optionally, during the preparation of the ultrasonic transducer 100, the first enclosure structure 81 can be prepared before the top electrode 40. The first enclosure structure 81 that forms the accommodating space is prepared first, and then the top electrode 40 is prepared in the accommodating space, thereby ensuring that the top electrode 40 is in a predetermined position and reducing the position error of the top electrode 40.

[0104] In some optional embodiments, the first enclosure structure 81 is a cured photoresist enclosure structure. Forming the first enclosure structure 81 by curing the photoresist is easy to process and manufacture, which can reduce the manufacturing difficulty of the ultrasonic transducer 100.

[0105] Optionally, when forming the first enclosure structure 81 during the preparation stage of the ultrasonic transducer 100, for example, in one feasible manner, a whole layer of first photoresist can be spin-coated on the upper surface of the substrate 10 (this is only an example, other feasible methods can also be used), and the first photoresist is cured and patterned by exposure and development, so that after the first photoresist is cured, a receiving space for preparing the top electrode 40 is formed to form the first enclosure structure 81. After the first enclosure structure 81 is formed, the top electrode 40 can be prepared in the receiving space, so that the top electrode 40 can be located in the receiving space, and the outer wall of the top electrode 40 is in contact with the inner wall of the first enclosure structure 81. It should be understood that this is only an example and is not a limitation of the embodiments of the present application.

[0106] Optionally, the first enclosure structure 81 may be a non-conductive material. Optionally, the first enclosure structure 81 may be made of an organic material, which may be, for example, at least one of the following materials: polyimide (PI), poly-p-phenylene benzobisoxazole (PBO), epoxy resin, acrylic resin, and the like. The first enclosure structure 81 may also be made of an organic silicone composite material. For example, an organic silicone composite material may include but is not limited to an organic silicone ring, silicone rubber, silicone resin material, and the like. It should be understood that in the present application, the first enclosure structure 81 may be made of the above-mentioned single material or a mixture of two different materials.

[0107] In some optional embodiments, referring to Figure 4 、 Figure 5A 、 Figure 7 and Figure 8 As shown, the angle between at least one inner sidewall of the first enclosure structure 81 and the normal of the substrate 10 is less than or equal to 45°.

[0108] Based on this, since the angle between at least one inner sidewall of the first enclosure structure 81 and the normal of the substrate 10 is less than or equal to 45°, and the top electrode 40 is located in the accommodation space enclosed by the first enclosure structure 81, and the outer sidewall of the top electrode 40 is in contact with the inner sidewall of the first enclosure structure 81, it can be ensured that the angle between at least one outer sidewall of the top electrode 40 and the normal of the substrate 10 is less than or equal to 45°, thereby effectively reducing the diffraction echo of the ultrasonic signal caused by the boundary morphology of the top electrode, thereby reducing the interference with the use of the ultrasonic transducer, improving the use effect of the ultrasonic transducer, and effectively improving the performance of the ultrasonic transducer. In addition, the above-mentioned angle range has low requirements for the preparation process, and it is relatively easy to form the first enclosure structure 81, thereby reducing the difficulty of preparing the ultrasonic transducer.

[0109] In some optional embodiments, referring to Figure 4 、 Figure 5A 、 Figure 7 and Figure 8 As shown, the angles between each inner sidewall of the first enclosure structure 81 and the normal of the substrate 10 are all less than or equal to 45°.

[0110] Based on this, since the angles between the inner sidewalls of the first enclosure structure 81 and the normal to the substrate 10 are all less than or equal to 45°, and the top electrode 40 is located in the accommodation space enclosed by the first enclosure structure 81, and the outer sidewalls of the top electrode 40 are in contact with the inner sidewalls of the first enclosure structure 81, it is possible to ensure that the angles between the outer sidewalls of the top electrode 40 and the normal to the substrate 10 are all less than or equal to 45°, thereby better reducing the diffraction echoes of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby better reducing the interference caused by this on the use of the ultrasonic transducer 100, better improving the use effect of the ultrasonic transducer 100, and more effectively improving the performance of the ultrasonic transducer. In addition, the above-mentioned angle range has low requirements for the preparation process, and it is relatively easy to form the first enclosure structure 81, thereby reducing the difficulty of preparing the ultrasonic transducer.

[0111] Preferably, the angle between at least one inner sidewall of the first enclosure structure 81 and the normal to the substrate 10 is less than or equal to 5°. In this case, it can be basically considered that the at least one inner sidewall of the first enclosure structure 81 is perpendicular to the substrate 10, thereby ensuring that the angle between at least one outer sidewall of the top electrode 40 and the normal to the substrate 10 is less than or equal to 5°. This ensures that at least one outer sidewall of the top electrode 40 is substantially 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 caused by the ultrasonic transducer 100 during use and improving the performance of the ultrasonic transducer 100.

[0112] Preferably, the angles between each inner sidewall of the first enclosure structure 81 and the normal to the substrate 10 are all less than or equal to 5°. In this case, it can be basically considered that each inner sidewall of the first enclosure structure 81 is perpendicular to the substrate 10, thereby ensuring that the angles between each outer sidewall of the top electrode 40 and the normal to the substrate 10 are all less than or equal to 5°. This makes each outer sidewall of the top electrode 40 substantially perpendicular to the substrate 10, which can better reduce the diffraction echoes of the ultrasonic signal caused by the boundary morphology of the top electrode 40, thereby reducing the interference with the use of the ultrasonic transducer 100 and improving the use effect of the ultrasonic transducer 100.

[0113] It should be understood that the closer the angle between each inner sidewall of the first enclosure structure 81 and the normal to the substrate 10 is to 0°, the closer the angle between each outer sidewall of the top electrode 40 and the normal to the substrate 10 is to 0°. Furthermore, the closer the angle between each outer sidewall of the top electrode 40 and the normal to the substrate 10 is to 0°, the closer the outer sidewall and the substrate 10 are to perpendicularity, and the better the performance of the ultrasonic transducer 100. Therefore, in some preferred embodiments, at least one inner sidewall of the first enclosure structure 81 in the present application can be equal to 0°. In some preferred embodiments, each inner sidewall of the first enclosure structure 81 in the present application can be equal to 0°.

[0114] For example, refer to Figure 9A The schematic diagram shown shows the angle between the inner sidewall of the exemplary first enclosure structure 81 and the normal to the substrate 10, and the angle between the outer sidewall of the exemplary top electrode 40 and the normal to the substrate 10. 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 inner sidewall of the first enclosure structure 81 and the outer sidewall of the top electrode 40 are both perpendicular to the normal to the substrate 10.

[0115] For example, refer to Figure 9BThe schematic diagram shown shows the angle between the inner sidewall of the first enclosure structure 81 and the normal to the substrate 10, as well as the angle between the outer sidewall of the top electrode 40 and the normal to the substrate 10, as another example. 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 inner sidewall of the first enclosure structure 81 and the outer sidewall of the top electrode 40 are both perpendicular to the normal to the substrate 10.

[0116] For example, refer to Figure 9C The schematic diagram shown shows an angle θ between the outer sidewall of the top electrode 40 and the normal to the substrate 10 in another example. 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 to the substrate 10.

[0117] For example, refer to Figure 9D The schematic diagram shown shows another example of an angle θ between the outer sidewalls of the top electrode 40 and the normal to the substrate 10. 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 sidewalls of the top electrode 40 are perpendicular to the normal to the substrate 10.

[0118] 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.

[0119] In some optional embodiments, the first enclosure structure 81 at least partially covers the outer side wall of the piezoelectric layer 30 , and / or the first enclosure structure 81 is at least partially located in an edge region of the upper surface of the piezoelectric layer 30 .

[0120] In the present application, by at least partially covering the outer wall of the piezoelectric layer 30 and / or the first enclosure structure 81 located in the edge area of ​​the upper surface of the piezoelectric layer 30, an accommodation space can be effectively formed at the desired position, so as to facilitate the preparation of a top electrode 40 with better performance during the preparation process of the ultrasonic transducer 100.

[0121] For example, you can combine Figure 4 In the ultrasonic transducer 100 shown, the first enclosure structure 81 is formed at least partially on the upper surface of the piezoelectric layer 30. For example, Figure 7 and Figure 8 In the ultrasonic transducer 100 shown, the first enclosure structure 81 formed therein partially covers the outer side wall of the piezoelectric layer 30. Figure 5AIn the ultrasonic transducer 100 shown, the first enclosure structure 81 partially covers the outer sidewall of the piezoelectric layer 30 and is partially located in the edge region of the upper surface of the piezoelectric layer 30. It should be understood that the above schematic diagrams are merely examples for ease of understanding and do not constitute any limitation on the embodiments of the present application.

[0122] In some optional embodiments, the ultrasonic transducer 100 may include a first enclosure structure 81 and a second enclosure structure 82. For example, referring to Figure 7 and Figure 8 As shown, the ultrasonic transducer 100 further includes a second enclosure structure 82, which is located on the upper surface of the substrate 10 and surrounds at least a portion of the piezoelectric layer 30. The top electrode 40 is at least partially in contact with the second enclosure structure 82, and the piezoelectric layer 30 is enclosed between the top electrode 40 and the second enclosure structure 82. Furthermore, the first enclosure structure 81 is at least partially located on the upper surface of the second enclosure structure 82. A gap exists between the first enclosure structure 81 formed on the upper surface of the second enclosure structure 82 and the piezoelectric layer 30. It should be understood that the presence of the gap allows a portion of the top electrode to extend beyond the piezoelectric layer 30 and contact the second enclosure structure 82, which can enhance bonding strength.

[0123] Based on this, the first enclosure structure 81 can be formed into a holding space to facilitate the preparation of the top electrode 40, and the top electrode 40 can be protected by the first enclosure structure 81 to ensure the performance of the top electrode 40; on the other hand, the second enclosure structure 82 can at least be used to protect the piezoelectric layer 30 to ensure the performance of the piezoelectric layer 30 and improve the performance of the ultrasonic transducer 100; on the other hand, since the top electrode 40 is at least partially in contact with the second enclosure structure 82, the piezoelectric layer 30 is wrapped between the top electrode 40 and the second enclosure structure 82, thereby supporting the top electrode 40 to exceed the piezoelectric layer 30, and preventing the top electrode 40 from being blocked by the second enclosure structure 82 without Directly contact the electrically sensitive area on the substrate 10 to avoid short circuit or discharge breakdown. In addition, the top electrode 40 can protect the piezoelectric layer 30 together with the second enclosure structure 82, so as to better protect the piezoelectric layer 30, better ensure the performance of the piezoelectric layer 30, and better improve the performance of the ultrasonic transducer 100. On the other hand, the second enclosure structure 82 can be used as a contact buffer between the piezoelectric layer 30 and the top electrode 40. The top electrode 40 can indirectly improve the structural stability between the piezoelectric layer 30 and the top electrode 40 by contacting the second enclosure structure 82, which is beneficial to improve the structural stability of the ultrasonic transducer 100 and improve the performance of the ultrasonic transducer 100.

[0124] In addition, since the top electrode 40 and the second enclosure structure 82 can protect the piezoelectric layer 30, the process compatibility when preparing the ultrasonic transducer 100 is improved, the process difficulty is reduced, and the range of optional materials such as solvents used in subsequent preparation processes can be expanded.

[0125] For example, Figure 7 and Figure 8 In the ultrasonic transducer 100 , at least a portion of the top electrode 40 may be in direct contact with the second enclosure structure 82 .

[0126] In some optional implementations, reference Figure 7 As shown, the piezoelectric layer 30 at least partially covers the upper surface of the second enclosure structure 82. Figure 7 As shown, a portion of both sides of the piezoelectric layer 30 is covered above the second enclosure structure 82 .

[0127] In the present application, the piezoelectric layer 30 is at least partially covered on the upper surface of the second enclosure structure 82, and then the structural stability between the piezoelectric layer 30 and the substrate 10 can be indirectly improved by covering the second enclosure structure 82, which is beneficial to improving the structural reliability of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100.

[0128] In some optional embodiments, referring to Figure 8 As shown, the second enclosure structure 82 partially covers the upper surface of the piezoelectric layer 30. For example, Figure 8 As shown, a portion of both sides of the second enclosure structure 82 covers the upper surface of the piezoelectric layer 30 .

[0129] In the present application, by partially covering the upper surface of the piezoelectric layer 30 with the second enclosure structure 82, the second enclosure structure 82 can better protect the piezoelectric layer 30 to ensure the performance of the piezoelectric layer 30 and improve the performance of the ultrasonic transducer 100. In addition, the top electrode 40 can be blocked by the second enclosure structure 82 without directly contacting the electrically sensitive area on the substrate 10, thereby better avoiding causing a short circuit or discharge breakdown. In addition, the top electrode 40 can be more conveniently covered with the second enclosure structure 82 during preparation, so as to indirectly improve the structural stability between the piezoelectric layer 30 and the top electrode 40 through the second enclosure structure 82, which is beneficial to improving the structural stability of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100.

[0130] In some optional embodiments, the second enclosure structure 82 is a cured photoresist enclosure structure. Forming the second enclosure structure 82 by curing the photoresist is easy to process and manufacture, which can reduce the manufacturing difficulty of the ultrasonic transducer 100.

[0131] Optionally, when forming the second enclosure structure 82 during the preparation stage of the ultrasonic transducer 100, for example, in a feasible manner, the second enclosure structure 82 can be prepared before the piezoelectric layer 30, and then a whole layer of second photoresist can be spin-coated on the upper surface of the substrate 10 (only as an example, other feasible methods can also be used), and the second photoresist is patterned and cured by exposure and development, so that the second photoresist surrounds the outside of the bottom electrode 20 after curing, so as to form a second enclosure structure 82 in the peripheral area of ​​the bottom electrode 20 on the upper surface of the substrate 10, and the second enclosure structure 82 covers at least a portion of the bottom electrode 20. After the second enclosing structure 82 is exposed, the piezoelectric layer 30 can be prepared on the bottom electrode 20 exposed by the second enclosing structure 82. For example, in another feasible manner, the second enclosing structure 82 can be prepared after the piezoelectric layer 30. Then, after the piezoelectric layer 30 is formed on the substrate 10, a whole layer of second photoresist can be spin-coated (only as an example, other feasible methods can also be used) on the upper surface of the substrate 10, and the second photoresist is cured and patterned by exposure and development, so that after the second photoresist is cured, a second enclosing structure 82 surrounding the outside of the piezoelectric layer 30 is formed, and the second enclosing structure 82 exposes at least part of the piezoelectric layer 30. Thereafter, the top electrode 40 can be prepared by any feasible method, so that the top electrode 40 is at least partially in contact with the second enclosing structure 82, so that the piezoelectric layer 30 is enclosed between the top electrode 40 and the second enclosing structure 82. It should be understood that the above is only an example and is not a limitation of the embodiments of the present application.

[0132] In some optional embodiments, reference Figure 7 As shown, the thickness of the second enclosure structure 82 may be less than the thickness of the piezoelectric layer 30. In other optional embodiments, referring to Figure 8 As shown, the thickness of the second enclosure structure 82 may also be greater than the thickness of the piezoelectric layer 30. This may be selected as needed and is not limited here.

[0133] It is understood that in other optional embodiments, the ultrasonic transducer 100 may include only the second enclosure structure 82 and may not include the first enclosure structure 81. This situation may include the ultrasonic transducer including the seed metal layer 50 as described above, or may be an ultrasonic transducer 100 not including the seed metal layer 50.

[0134] For the ultrasonic transducer 100 including the seed metal layer 50, in some optional embodiments, refer to Figure 2A 、 Figure 3 As shown, the ultrasonic transducer 100 also includes: a second enclosure structure 82, which is located on the upper surface of the substrate 10, and the second enclosure structure 82 surrounds at least a portion of the piezoelectric layer 30; at least a portion of the seed metal layer 50 is arranged between at least a portion of the top electrode 40 and the second enclosure structure 82, and the piezoelectric layer 30 is coated between the seed metal layer 50 and the second enclosure structure 82.

[0135] Based on this, on the one hand, the second enclosure structure 82 can at least be used to protect the piezoelectric layer 30 to ensure the performance of the piezoelectric layer 30 and improve the performance of the ultrasonic transducer 100; on the other hand, at least part of the seed metal layer 50 is arranged between at least part of the top electrode 40 and the second enclosure structure 82, so that the top electrode 40 can at least partially contact the second enclosure structure 82 through the seed metal layer 50, and the piezoelectric layer 30 is coated between the seed metal layer 50 and the second enclosure structure 82, thereby supporting the top electrode 40 to extend beyond the piezoelectric layer 30, so that the top electrode 40 can pass through the obstruction of the second enclosure structure 82 without directly contacting the electrically sensitive substrate 10. Sensing area, to avoid short circuit or discharge breakdown. In addition, the top electrode 40 and the second enclosure structure 82 can protect the piezoelectric layer 30, so as to better protect the piezoelectric layer 30, better ensure the performance of the piezoelectric layer 30, and better improve the performance of the ultrasonic transducer 100. On the other hand, the second enclosure structure 82 can be used as a contact buffer between the piezoelectric layer 30 and the top electrode 40. The top electrode 40 can contact the second enclosure structure 82 through the seed metal layer 50 to indirectly improve the structural stability between the piezoelectric layer 30 and the top electrode 40, which is beneficial to improve the structural stability of the ultrasonic transducer 100 and improve the performance of the ultrasonic transducer 100.

[0136] In addition, since the top electrode 40 and the second enclosure structure 82 can protect the piezoelectric layer 30, the process compatibility when preparing the ultrasonic transducer 100 is improved, the process difficulty is reduced, and the range of optional materials such as solvents used in subsequent preparation processes can be expanded.

[0137] For example, Figure 2A 、 Figure 3 In the ultrasonic transducer 100 , at least a portion of the top electrode 40 may contact the second enclosure structure 82 through the seed metal layer 50 .

[0138] In some optional implementations, reference Figure 2A As shown, the piezoelectric layer 30 at least partially covers the upper surface of the second enclosure structure 82. Figure 2A As shown, a portion of both sides of the piezoelectric layer 30 is covered above the second enclosure structure 82 .

[0139] In the present application, the piezoelectric layer 30 is at least partially covered on the upper surface of the second enclosure structure 82, and then the structural stability between the piezoelectric layer 30 and the substrate 10 can be indirectly improved by covering the second enclosure structure 82, which is beneficial to improving the structural reliability of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100.

[0140] In some optional embodiments, referring to Figure 3As shown, the second enclosure structure 82 partially covers the upper surface of the piezoelectric layer 30. For example, Figure 3 As shown, a portion of both sides of the second enclosure structure 82 covers the upper surface of the piezoelectric layer 30 .

[0141] In the present application, by partially covering the upper surface of the piezoelectric layer 30 with the second enclosure structure 82, the second enclosure structure 82 can better protect the piezoelectric layer 30 to ensure the performance of the piezoelectric layer 30 and improve the performance of the ultrasonic transducer 100. In addition, the top electrode 40 can be blocked by the second enclosure structure 82 without directly contacting the electrically sensitive area on the substrate 10, thereby better avoiding causing a short circuit or discharge breakdown. In addition, the top electrode 40 can be more conveniently covered with the second enclosure structure 82 during preparation, so as to indirectly improve the structural stability between the piezoelectric layer 30 and the top electrode 40 through the second enclosure structure 82, which is beneficial to improving the structural stability of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100.

[0142] In some optional embodiments, the second enclosure structure 82 is a cured photoresist enclosure structure. Forming the second enclosure structure 82 by curing the photoresist is easy to process and manufacture, which can reduce the manufacturing difficulty of the ultrasonic transducer 100.

[0143] Optionally, when forming the second enclosure structure 82 during the preparation stage of the ultrasonic transducer 100, for example, in a feasible manner, the second enclosure structure 82 can be prepared before the piezoelectric layer 30, and then a whole layer of second photoresist can be spin-coated on the upper surface of the substrate 10 (only as an example, other feasible methods can also be used), and the second photoresist is patterned and cured by exposure and development, so that the second photoresist surrounds the outside of the bottom electrode 20 after curing, so as to form a second enclosure structure 82 in the peripheral area of ​​the bottom electrode 20 on the upper surface of the substrate 10, and the second enclosure structure 82 covers at least a portion of the bottom electrode 20. After the second enclosing structure 82 is exposed, the piezoelectric layer 30 can be prepared on the bottom electrode 20 exposed by the second enclosing structure 82. For example, in another feasible manner, the second enclosing structure 82 can be prepared after the piezoelectric layer 30. Then, after the piezoelectric layer 30 is formed on the substrate 10, a whole layer of second photoresist can be spin-coated (only as an example, other feasible methods can also be used) on the upper surface of the substrate 10, and the second photoresist is cured and patterned by exposure and development, so that after the second photoresist is cured, a second enclosing structure 82 surrounding the outside of the piezoelectric layer 30 is formed, and the second enclosing structure 82 exposes at least part of the piezoelectric layer 30. Thereafter, the top electrode 40 can be prepared by any feasible method, so that the top electrode 40 is at least partially in contact with the second enclosing structure 82, so that the piezoelectric layer 30 is enclosed between the top electrode 40 and the second enclosing structure 82. It should be understood that the above is only an example and is not a limitation of the embodiments of the present application.

[0144] In some optional embodiments, reference Figure 2A As shown, the thickness of the second enclosure structure 82 may be less than the thickness of the piezoelectric layer 30. In other optional embodiments, referring to Figure 3 As shown, the thickness of the second enclosure structure 82 may also be greater than the thickness of the piezoelectric layer 30. This may be selected as needed and is not limited here.

[0145] For the ultrasonic transducer 100 that does not include the seed metal layer 50, in some optional embodiments, the ultrasonic transducer 100 also includes: a second enclosure structure 82, the second enclosure structure 82 is located on the upper surface of the substrate 10, and the second enclosure structure 82 surrounds at least a portion of the piezoelectric layer 30; the piezoelectric layer 30 is coated between the top electrode 40 and the second enclosure structure 82; and the first enclosure structure 81 is at least partially located on the upper surface of the second enclosure structure 82.

[0146] Based on this, on the one hand, the second enclosure structure 82 can at least be used to protect the piezoelectric layer 30 to ensure the performance of the piezoelectric layer 30 and improve the performance of the ultrasonic transducer 100; on the other hand, since the top electrode 40 is at least partially in contact with the second enclosure structure 82, the piezoelectric layer 30 is wrapped between the top electrode 40 and the second enclosure structure 82, thereby supporting the top electrode 40 to extend beyond the piezoelectric layer 30, allowing the top electrode 40 to pass through the obstruction of the second enclosure structure 82 without directly contacting the electrically sensitive area on the substrate 10, thereby avoiding causing a short circuit or discharge breakdown. In addition, the top electrode 40 is The electrode 40 and the second enclosure structure 82 can protect the piezoelectric layer 30, thereby better protecting the piezoelectric layer 30, better ensuring the performance of the piezoelectric layer 30, and better improving the performance of the ultrasonic transducer 100; on the other hand, the second enclosure structure 82 can be used as a contact buffer between the piezoelectric layer 30 and the top electrode 40. The top electrode 40 can indirectly improve the structural stability between the piezoelectric layer 30 and the top electrode 40 by contacting the second enclosure structure 82, which is beneficial to improving the structural stability of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100.

[0147] In addition, since the top electrode 40 and the second enclosure structure 82 can protect the piezoelectric layer 30, the process compatibility when preparing the ultrasonic transducer 100 is improved, the process difficulty is reduced, and the range of optional materials such as solvents used in subsequent preparation processes can be expanded.

[0148] Optionally, the piezoelectric layer 30 at least partially covers the upper surface of the second enclosure structure 82. In the present application, by making the piezoelectric layer 30 at least partially cover the upper surface of the second enclosure structure 82, the structural stability between the piezoelectric layer 30 and the substrate 10 can be indirectly improved by covering the second enclosure structure 82, thereby facilitating improvement of the structural reliability of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100.

[0149] Optionally, the second enclosure structure 82 partially covers the upper surface of the piezoelectric layer 30. In the present application, by making the second enclosure structure 82 partially cover the upper surface of the piezoelectric layer 30, the second enclosure structure 82 can better protect the piezoelectric layer 30 to ensure the performance of the piezoelectric layer 30 and improve the performance of the ultrasonic transducer 100. In addition, the top electrode 40 can be blocked by the second enclosure structure 82 without directly contacting the electrically sensitive area on the substrate 10, thereby better avoiding short circuits or discharge breakdown. In addition, the top electrode 40 can be more conveniently covered with the second enclosure structure 82 during preparation, so as to indirectly improve the structural stability between the piezoelectric layer 30 and the top electrode 40 through the second enclosure structure 82, which is beneficial to improving the structural stability of the ultrasonic transducer 100 and improving the performance of the ultrasonic transducer 100.

[0150] Optionally, the second enclosure structure 82 is a cured photoresist enclosure structure. Forming the second enclosure structure 82 by curing the photoresist facilitates processing and fabrication, reducing the manufacturing complexity of the ultrasonic transducer 100. This optional embodiment has been previously described. The beneficial effects and detailed description can be understood by referring to the relevant content above and will not be repeated here.

[0151] In some optional embodiments, the top electrode 40 may be a single metal layer, a multi-layer metal stack, or an alloy layer.

[0152] In some optional embodiments, the top electrode 40 can be made of any suitable metal material. For example, it can include but is not limited to at least one of tin, copper, nickel, gold, silver, chromium, zinc, titanium, and lead, or an alloy of at least two of tin, copper, nickel, gold, silver, chromium, zinc, titanium, and lead. That is, optionally, the top electrode 40 can be at least one of a tin layer, a copper layer, a nickel layer, a gold layer, a silver layer, an indium layer, a chromium layer, a zinc layer, a titanium layer, and a lead layer, or the top electrode 40 can be an alloy layer of at least two of tin, copper, nickel, gold, silver, indium, chromium, zinc, titanium, and lead. For example, an example of an alloy layer is a tin-silver alloy layer. It should be understood that the top electrode 40 in the above form can effectively ensure the performance of the top electrode 40, and thus ensure the performance of the prepared ultrasonic transducer.

[0153] For the optional embodiment in which the top electrode 40 is an electroplated metal layer, due to the characteristics of electroplating, the top electrode 40 can be a pure metal layer. For example, optionally, the top electrode 40 can be at least one of a pure tin layer, a pure copper layer, a pure nickel layer, a pure gold layer, a pure silver layer, a pure indium layer, a pure chromium layer, a pure zinc layer, a pure titanium layer, and a pure lead layer. When the top electrode 40 is electroplated with at least two of the above-mentioned metal materials of tin, copper, nickel, gold, silver, indium, chromium, zinc, titanium, and lead to obtain the top electrode 40, that is, when it can be at least two of the above-mentioned pure tin layer, pure copper layer, pure nickel layer, pure gold layer, pure silver layer, pure indium layer, pure chromium layer, pure zinc layer, pure titanium layer, and pure lead layer, then the top electrode 40 can be a metal stack. For example, in one example, the top electrode 40 can be a stack of pure copper and pure tin, for example, the copper layer can be electroplated first and then the tin layer can be electroplated to obtain the top electrode 40. Alternatively, the top electrode 40 is an alloy layer of at least two of pure tin, pure copper, pure nickel, pure gold, pure silver, pure indium, pure chromium, pure zinc, pure titanium, and pure lead. For example, an example of an alloy layer is a pure tin and pure silver alloy layer. It should be understood that the above-described top electrode 40 can effectively ensure the performance of the top electrode 40, and thus the performance of the resulting ultrasonic transducer.

[0154] It should be noted that, except for some of the above-mentioned preferred technical solutions of this application, there are no cases of top electrodes in the form of tin layers in the related art. For example, the reason why tin is used to form the top electrode 40 in the form of an electroplated metal layer in some preferred embodiments of this application is that: on the one hand, for ultrasonic transducers, the top electrode 40 can usually reach the required target thickness through a single electroplating operation during preparation, reducing the process difficulty and time cycle, and reducing the probability of production abnormalities; on the other hand, the related art often uses silver (Ag) paste for multi-layer silk screen printing to prepare the top electrode. The silver paste used for silk screen printing is generally composed of silver (Ag) particles + resin + solvent + additives, etc. After silk screen printing, it is cured by baking to remove most of the solvent, and finally only micron or nanometer-sized silver particles and part of the resin remain. However, it is relatively easy to have abnormalities such as internal air voids or resin agglomeration, which will affect the performance of the product. The internal quality of the electroplated tin metal material in this application is better than that of the silk-screened silver (Ag) paste. Tin is used to form the top electrode 40 in the form of an electroplated metal layer, and a top electrode 40 made of tin can be obtained by electroplating. The interior is dense and has no abnormalities such as stratification, holes, or resin agglomeration, and the thickness tolerance is small, and the quality stability is better. Therefore, the performance of the top electrode 40 in the form of the electroplated metal layer can be improved, thereby improving the performance of the ultrasonic transducer 100; on the other hand, the top electrode 40 in the form of a tin layer is made of cheaper materials, which can significantly reduce the cost of the ultrasonic transducer 100.

[0155] Of course, the thickness of the top electrode 40 can be selected as needed. For example, for the ultrasonic transducer 100 with the seed metal layer 50, refer to Figure 1A 、 Figure 2A 、 Figure 3 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 seed metal layer 50. For example, for the ultrasonic transducer 100 without the seed metal layer 50, Figure 4 、 Figure 5A 、 Figure 6A 、 Figure 7 and Figure 8 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 μm. The top electrode 40 within this thickness range is not too thick and can effectively meet the performance requirements of the ultrasonic transducer 100.

[0156] Preferably, the thickness of the top electrode 40 may be in the range of 10 μm to 40 μm. 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 .

[0157] For example, within the range of 10 um to 40 um, the thickness of the top electrode may be 10 um, 15 um, 20 um, 25 um, 30 um, 35 um, 40 um, etc., or may be other values.

[0158] Preferably, the thickness of the top electrode 40 may be in the range of 15 μm to 40 μm. 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 .

[0159] In some optional embodiments, the elastic modulus of the top electrode 40 is less than 130 GPa. Obtaining the top electrode 40 within the elastic modulus range of less than 130 GPa can adapt to stress matching between the stacked materials of the ultrasonic transducer, achieve minimal warpage, and thus improve the performance of the ultrasonic transducer.

[0160] For example, the top electrode 40 may be made of a metal material having an elastic modulus less than 130 GPa to meet the above elastic modulus range condition.

[0161] In some optional embodiments, the acoustic impedance of the top electrode 40 is less than 35 MRayl (i.e., MPa·s / m 3 , megapascal seconds per cubic meter).

[0162] It should be understood that the acoustic impedance matching of the ultrasonic transducer laminated structure needs to be considered. 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 waves will be significantly consumed during the propagation process. Therefore, by using the top electrode 40 with an acoustic impedance range of less than 35 MRayl, the acoustic impedance difference between the materials of each laminated structure of the ultrasonic transducer 100 (such as the material of the substrate 10 (such as but not limited to silicon Si material, etc.), the material of the enclosure structure that needs to be retained (such as but not limited to organic glue material, etc.), the material of the piezoelectric layer 30, etc.) can be reduced as much as possible, thereby improving the performance of the top electrode 40 and improving the acoustic performance of the prepared ultrasonic transducer 100.

[0163] For example, the top electrode 40 can be made of at least one of the above-mentioned tin, copper, nickel, gold, silver, chromium, zinc, titanium, and lead, or an alloy of at least two of the above metal materials that meet the elastic modulus and acoustic impedance range conditions. The top electrode 40 can be at least one of a tin layer, a copper layer, a nickel layer, a gold layer, a silver layer, an indium layer, a chromium layer, a zinc layer, a titanium layer, and a lead layer. When the top electrode 40 is at least two of the tin layer, the copper layer, the nickel layer, the gold layer, the silver layer, the indium layer, the chromium layer, the zinc layer, the titanium layer, and the lead layer, the top electrode is a metal stack. For example, the top electrode 40 can be a stack of copper and tin. Alternatively, the top electrode 40 can be an alloy layer of at least two of tin, copper, nickel, gold, silver, indium, chromium, zinc, titanium, and lead. For example, an example of an alloy layer is a tin-silver alloy layer. Alternatively, when the top electrode 40 is an electroplated metal layer, it may be at least one of a pure tin layer, a pure copper layer, a pure nickel layer, a pure gold layer, a pure silver layer, a pure indium layer, a pure chromium layer, a pure zinc layer, a pure titanium layer, and a pure lead layer; or it may be a metal stack of at least two of the above pure metal layers (pure tin layer, pure copper layer, pure nickel layer, pure gold layer, pure silver layer, pure indium layer, pure chromium layer, pure zinc layer, pure titanium layer, and pure lead layer). For example, a stack of pure copper and pure tin. Alternatively, the top electrode 40 is an alloy layer of at least two of pure tin, pure copper, pure nickel, pure gold, pure silver, pure indium, pure chromium, pure zinc, pure titanium, and pure lead. For example, an example of an alloy layer is a pure tin and pure silver alloy layer.

[0164] In some optional embodiments, the surface roughness of the top electrode 40 of the present application can meet at least one of the following conditions: the average roughness Ra (Roughness Average) over the reference length is less than 0.8 μm, and the maximum roughness Rz over the reference length is less than 3 μm. Based on this, the top electrode 40 can effectively have a better appearance and a smaller thickness tolerance, a smoother surface with no obvious undulations, less graininess, and less noticeable wrinkles or orange peel, which is beneficial for improving the performance of the prepared ultrasonic transducer 100.

[0165] It should be understood that the above description is merely some optional embodiments of the ultrasonic transducer solution of the embodiment of the present application, and does not constitute any limitation to the embodiment of the present application.

[0166] According to the second aspect of the embodiment of the present application, referring to Figure 11 As shown, an ultrasonic fingerprint module 200 is provided, comprising: the ultrasonic transducer 100 provided in the first aspect.

[0167] Since the ultrasonic fingerprint module 200 of the second aspect includes the ultrasonic transducer 100 of the first aspect, it has better performance and can better realize the ultrasonic fingerprint function.

[0168] In some optional embodiments, the ultrasonic fingerprint module 200 further includes an adhesive layer, and the adhesive layer is used to adhere the ultrasonic transducer 100 of the ultrasonic fingerprint module 200 to the fingerprint pressing surface of the electronic device.

[0169] According to the third aspect of the embodiment of this application, referring to Figure 12A 、 Figure 12B As shown, an electronic device 300 is provided, comprising: the ultrasonic transducer 100 provided in the first aspect, or the ultrasonic fingerprint module 200 provided in the second aspect.

[0170] In some optional embodiments, the electronic device 300 further includes a screen 320, a back panel, and side frames.

[0171] Optionally, when the electronic device 300 includes the ultrasonic transducer 100 , the ultrasonic transducer 100 may be attached to the lower surface of the screen 320 or to the inner side of the back plate or to the inner side of the side frame.

[0172] Optionally, when the electronic device 300 includes an ultrasonic fingerprint module 200, the ultrasonic fingerprint module 200 can be attached to the lower surface of the screen 320, or to the inner side of the back panel, or to the inner side of the side frame. That is, the ultrasonic fingerprint module 200 can be an under-screen ultrasonic fingerprint module, a rear ultrasonic fingerprint module, or a side ultrasonic fingerprint module of the electronic device 300. This enables under-screen ultrasonic fingerprint recognition, rear ultrasonic fingerprint recognition, or side ultrasonic fingerprint recognition.

[0173] 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 .

[0174] As an example, taking the electronic device 300 as a mobile phone and including the ultrasonic transducer 100 as an example, refer to Figure 13As 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. Figure 13 China is Figure 2A The optional ultrasonic transducer 100 is provided as an example for ease of understanding and does not constitute any limitation to the present application. The same can be applied to any other optional ultrasonic transducer in the embodiment, and no additional examples are given here for elaboration.

[0175] 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 via an adhesive layer to achieve under-screen ultrasonic fingerprint recognition. It should be understood that in the optional embodiment where the ultrasonic fingerprint module 200 is an ultrasonic fingerprint module on the back or side of the electronic device 300, the adhesive connection can also be achieved via an adhesive layer.

[0176] 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.

[0177] It will be understood that the above descriptions of various aspects of the embodiments of the present application are merely some optional exemplary descriptions of the technical solutions of the embodiments of the present application, and do not constitute any limitations on the embodiments of the present application.

[0178] The optional implementation modes of the embodiments of the present application are described in detail above with reference to the accompanying drawings, but the embodiments of the present application are not limited thereto. It should be noted that, for the convenience of illustrating 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. They are only used to facilitate the explanation of the technical solution and are not used to impose any restrictions on the embodiments of the present application. Within the scope of 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 no longer describe various possible combinations separately. 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 scope of protection of the embodiments of the present application.

[0179] 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 "a plurality of" mentioned in this application are illustrative rather than restrictive. Those skilled in the art should understand that unless the context clearly indicates otherwise, it should be understood as "one or more".

[0180] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, and not to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An ultrasonic transducer, characterized in that: include: 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; 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°.

2. The ultrasonic transducer according to claim 1, characterized in that 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°.

3. The ultrasonic transducer according to claim 1, characterized in that An angle between at least one outer sidewall of the top electrode and a normal line of the substrate is equal to 0°.

4. The ultrasonic transducer according to claim 1, characterized in that The connection between the outer side wall of the top electrode and the upper surface of the top electrode is arc-shaped.

5. The ultrasonic transducer according to claim 1, characterized in that The ultrasonic transducer further includes a pad area, which is provided on the substrate and electrically connected to the bottom electrode; the pad area is electrically connected to the top electrode; and the pad area is further used to connect to an external circuit.

6. The ultrasonic transducer according to claim 5, characterized in that The ultrasonic transducer further includes an excitation electrode, which is disposed on the upper surface of the substrate and is not in contact with the bottom electrode. The top electrode is electrically connected to the excitation electrode, and the excitation electrode is electrically connected to the pad area.

7. The ultrasonic transducer according to claim 1, characterized in that The ultrasonic transducer further includes a protective layer, which covers at least the upper surface of the top electrode to protect at least a portion of the top electrode.

8. The ultrasonic transducer according to claim 1, characterized in that The ultrasonic transducer also includes a seed metal layer, which is located between the piezoelectric layer and the top electrode, and the thickness of the seed metal layer is less than the thickness of the top electrode; the top electrode is an electroplated metal layer formed on the upper surface of the seed metal layer; the thickness of the seed metal layer is less than or equal to 2um; the thickness of the top electrode ranges from 10um to 40um; the top electrode is a single metal layer, a multi-layer metal stack or an alloy layer.

9. The ultrasonic transducer according to claim 8, characterized in that The top electrode is at least one of a pure tin layer, a pure copper layer, a pure nickel layer, a pure gold layer, a pure silver layer, a pure indium layer, a pure chromium layer, a pure zinc layer, a pure titanium layer, and a pure lead layer; or, the top electrode is an alloy layer of at least two of pure tin, pure copper, pure nickel, pure gold, pure silver, pure indium, pure chromium, pure zinc, pure titanium, and pure lead.

10. The ultrasonic transducer according to claim 8, characterized in that The seed metal layer includes a first metal layer and a second metal layer, wherein the first metal layer is located between the piezoelectric layer and the second metal layer, and the second metal layer is located between the first metal layer and the top electrode; wherein the resistivity of the first metal layer is higher than the resistivity of the second metal layer; The thickness of the first metal layer is less than or equal to 1um, and the thickness of the second metal layer is less than 2um; the first metal layer is at least one of a titanium layer, a titanium-tungsten alloy layer, and a chromium layer, and / or the second metal layer is at least one of a copper layer, a gold layer, and a nickel-vanadium alloy layer.

11. The ultrasonic transducer according to claim 8, characterized in that The ultrasonic transducer further includes: a second enclosure structure, the second enclosure structure being located on the upper surface of the substrate, the second enclosure structure surrounding at least a portion of the piezoelectric layer; At least a portion of the seed metal layer is disposed between at least a portion of the top electrode and the second enclosure structure, and the piezoelectric layer is enclosed between the seed metal layer and the second enclosure structure; At least a portion of the piezoelectric layer covers at least a portion of the upper surface of the second enclosure structure, or at least a portion of the second enclosure structure covers at least a portion of the upper surface of the piezoelectric layer.

12. The ultrasonic transducer according to claim 1, characterized in that The ultrasonic transducer also includes: a first enclosure structure, the first enclosure structure forms a accommodating space, the top electrode is located in the accommodating space, and the outer wall of the top electrode is in contact with the inner wall of the first enclosure structure; the thickness of the first enclosure structure is greater than or equal to the thickness of the top electrode.

13. The ultrasonic transducer according to claim 12, characterized in that: An angle between at least one inner sidewall of the first enclosure structure and a normal line of the substrate is less than or equal to 45°.

14. The ultrasonic transducer according to claim 12, characterized in that An angle between at least one inner sidewall of the first enclosure structure and a normal line of the substrate is less than or equal to 5°.

15. The ultrasonic transducer according to claim 12, characterized in that An angle between at least one inner sidewall of the first enclosure structure and a normal line of the substrate is equal to 0°.

16. The ultrasonic transducer according to claim 12, characterized in that The first enclosure structure is a cured photoresist enclosure structure; The first enclosure structure at least partially covers an outer sidewall of the piezoelectric layer, and / or the first enclosure structure is at least partially located in an edge region of an upper surface of the piezoelectric layer.

17. The ultrasonic transducer according to any one of claims 1 to 10, characterized in that: The ultrasonic transducer further includes: a second enclosure structure, the second enclosure structure being located on the upper surface of the substrate, the second enclosure structure surrounding at least a portion of the piezoelectric layer; The piezoelectric layer is coated between the top electrode and the second enclosure structure; the second enclosure structure is a cured photoresist enclosure structure; The piezoelectric layer at least partially covers the upper surface of the second enclosure structure, or the second enclosure structure partially covers the upper surface of the piezoelectric layer.

18. The ultrasonic transducer according to any one of claims 12 to 16, characterized in that: The ultrasonic transducer further includes a second enclosure structure, the second enclosure structure being located on the upper surface of the substrate and surrounding at least a portion of the piezoelectric layer; The top electrode is at least partially in contact with the second enclosing structure, and the piezoelectric layer is enclosed between the top electrode and the second enclosing structure; Furthermore, the first enclosure structure is at least partially located on the upper surface of the second enclosure structure; There is a distance between the first enclosure structure formed on the upper surface of the second enclosure structure and the piezoelectric layer.

19. The ultrasonic transducer according to claim 18, characterized in that The second enclosure structure is a cured photoresist enclosure structure; The piezoelectric layer at least partially covers the upper surface of the second enclosure structure, or the second enclosure structure partially covers the upper surface of the piezoelectric layer.

20. The ultrasonic transducer according to any one of claims 1 to 16, characterized in that: The top electrode satisfies at least one of the following conditions: The elastic modulus of the top electrode is less than 130 GPa; The acoustic impedance of the top electrode is less than 35 MRayl; The average roughness Ra of the surface of the top electrode is less than 0.8 μm; The maximum roughness Rz of the surface of the top electrode is less than 3 μm; The top electrode is at least one of a tin layer, a copper layer, a nickel layer, a gold layer, a silver layer, an indium layer, a chromium layer, a zinc layer, a titanium layer, and a lead layer; or, the top electrode is an alloy layer of at least two of tin, copper, nickel, gold, silver, indium, chromium, zinc, titanium, and lead.

21. An ultrasonic fingerprint module, characterized in that: include: The ultrasonic transducer according to any one of claims 1 to 20.

22. An electronic device, characterized in that: include: The ultrasonic fingerprint module, screen, back panel and side frame according to claim 21, wherein the ultrasonic fingerprint module is attached to the lower surface of the screen or to the inner side of the back panel or to the inner side of the side frame.

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