Ultrasonic transducer, ultrasonic fingerprint module and electronic device

Abstract

Embodiments of the present application provide an ultrasonic transducer, an ultrasonic fingerprint module and an electronic device. The ultrasonic transducer comprises: a substrate; a bottom electrode comprising a plurality of sub-electrodes located on the upper surface of the substrate; a passivation layer located above the substrate and partially covering the bottom electrode, the passivation layer being provided with a plurality of windowed portions corresponding to the positions of the plurality of sub-electrodes; and a piezoelectric layer located above the passivation layer and partially embedded in the plurality of windowed portions; wherein the plurality of sub-electrodes comprises at least a first sub-electrode and a second sub-electrode, a first windowed area of the windowed portion corresponding to the first sub-electrode is greater than a second windowed area of the windowed portion corresponding to the second sub-electrode, and the second sub-electrode is closer to the edge of the target side of the bottom electrode than the first sub-electrode.

Description

Technical Field

[0001] This application relates to the field of ultrasonic transducer technology, and more particularly to an ultrasonic transducer, an ultrasonic fingerprint module, and an electronic device. Background Technology

[0002] Ultrasonic transducers utilize the mechanical-electric conversion properties of piezoelectric materials. On the one hand, they can be excited by the voltage output from the driving circuit to emit ultrasonic signals. On the other hand, they can convert the ultrasonic signals reflected from the outside into electrical signals, thereby obtaining information about the external sensing surface. They can be widely used in fields including but not limited to biometric identification (for example, an example application could be for ultrasonic fingerprint modules, which can acquire fingerprint images to achieve fingerprint recognition).

[0003] Ultrasonic transducers in related technologies suffer from performance issues. For example, ultrasonic transducers typically consist of a bottom electrode and a top electrode. Due to certain manufacturing processes of the top electrode, edge effects can easily occur in the electrode structure (e.g., the thickness of some edge regions of the top electrode is greater than that of the central region). This leads to a lower local resonant frequency and poor uniformity of the ultrasonic amplitude, resulting in local non-uniformity in the detection data and affecting the local quality of the subsequent ultrasonic images, thus causing poor performance of the ultrasonic transducer.

[0004] Therefore, it is necessary to provide some new technical solutions for ultrasonic transducers to improve their performance. Utility Model Content

[0005] This application provides an ultrasonic transducer, an ultrasonic fingerprint module, and an electronic device.

[0006] According to a first aspect of the embodiments of this application, an ultrasonic transducer is provided, comprising: Substrate; The bottom electrode includes a plurality of sub-electrodes located on the upper surface of the substrate; A passivation layer is located above the substrate and partially covers the bottom electrode. The passivation layer is provided with a plurality of openings corresponding to the positions of a plurality of sub-electrodes. A piezoelectric layer is located above the passivation layer and is partially embedded in multiple openings; Among them, the plurality of sub-electrodes includes at least a first sub-electrode and a second sub-electrode. The first opening area of ​​the opening portion corresponding to the first sub-electrode is greater than the second opening area of ​​the opening portion corresponding to the second sub-electrode. The second sub-electrode is closer to the edge of the target side of the bottom electrode than the first sub-electrode.

[0007] According to a second aspect of the embodiments of this application, an ultrasonic transducer is provided, comprising: Substrate; The bottom electrode includes a plurality of sub-electrodes located on the upper surface of the substrate; A piezoelectric layer is located above the bottom electrode; The plurality of sub-electrodes includes at least a first sub-electrode and a second sub-electrode, and the piezoelectric layer includes a first portion of the piezoelectric layer and a second portion of the piezoelectric layer, wherein: The vertical projection of the first sub-electrode toward the substrate coincides with the vertical projection of the first portion of the piezoelectric layer toward the substrate, and the vertical projection of the second sub-electrode toward the substrate coincides with the vertical projection of the second portion of the piezoelectric layer toward the substrate; The volume of the first piezoelectric layer is larger than that of the second piezoelectric layer, and the second sub-electrode is closer to the edge of the target side of the bottom electrode than the first sub-electrode.

[0008] According to a third aspect of the embodiments of this application, an ultrasonic fingerprint module is provided, which includes: the ultrasonic transducer provided in the first or second aspect described above.

[0009] According to a fourth aspect of the embodiments of this application, an electronic device is provided, comprising: an ultrasonic transducer provided in the first or second aspect, or an ultrasonic fingerprint module provided in the third aspect.

[0010] The ultrasonic transducer in this embodiment has a passivation layer between the bottom electrode and the piezoelectric layer. The passivation layer has multiple openings corresponding to the positions of multiple sub-electrodes of the bottom electrode. The piezoelectric layer is located above the passivation layer and is partially embedded in the multiple openings. The multiple sub-electrodes include at least a first sub-electrode and a second sub-electrode. The first opening area of ​​the opening corresponding to the first sub-electrode is larger than the second opening area of ​​the opening corresponding to the second sub-electrode. The second sub-electrode is closer to the edge of the target side of the bottom electrode than the first sub-electrode. Therefore, in this embodiment, by making the window area of ​​the passivation layer corresponding to the second sub-electrode smaller than that corresponding to the first sub-electrode, the passivation layer can achieve relatively more coverage and constraint of the piezoelectric layer above the second sub-electrode at the edge closer to the target side of the bottom electrode. This can, to a certain extent, specifically compensate for the performance deviation of the local resonant frequency between the second sub-electrode and the first sub-electrode caused by the edge effect of the ultrasonic transducer electrode structure, thereby improving the potentially low local resonant frequency. This can further improve the uniformity of the local resonant frequency between the first and second sub-electrodes, effectively improve the uniformity of the ultrasonic amplitude between the second and first sub-electrodes, and improve the local uniformity of the detection data at both locations. This is beneficial for improving the local quality of the subsequently obtained ultrasonic image, thus significantly improving the performance of the ultrasonic transducer. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0012] Figure 1A A partial schematic diagram of an example ultrasonic transducer with a top electrode fabricated using a printing process is shown.

[0013] Figure 1B A top view schematic diagram of an example ultrasonic transducer is shown.

[0014] Figure 1C It shows Figure 1B The diagram shows the distribution of ultrasonic resonant frequencies in different regions of an ultrasonic transducer, as illustrated in the example.

[0015] Figure 1D It shows Figure 1B The example shows the ultrasonic amplitude distribution in different regions of an ultrasonic transducer.

[0016] Figure 2 A schematic diagram of an example ultrasonic transducer is shown in an embodiment of this application.

[0017] Figure 3 It shows Figure 2 A magnified view of a portion of point T in the middle.

[0018] Figure 4 A top view schematic diagram of an example ultrasonic transducer according to an embodiment of this application is shown.

[0019] Figure 5 A schematic diagram of another example of an ultrasonic transducer in an embodiment of this application is shown.

[0020] Figure 6 A schematic diagram showing some windowed states of the passivation layer in an embodiment of this application is shown.

[0021] Figure 7 A schematic block diagram of an example ultrasonic fingerprint module according to an embodiment of this application is shown.

[0022] Figure 8A A schematic block diagram of an example electronic device according to an embodiment of this application is shown.

[0023] Figure 8B A schematic block diagram of an electronic device, representing another example of an embodiment of this application, is shown.

[0024] Figure 9 A flowchart illustrating a method for fabricating an ultrasonic transducer according to an embodiment of this application is shown.

[0025] Explanation of reference numerals in the attached figures: 100. Ultrasonic transducer; 10. Substrate; 20. Bottom electrode; 21. Sub-electrode; 211. First sub-electrode; 212. Second sub-electrode; 30. Piezoelectric layer; 31. First portion of piezoelectric layer; 32. Second portion of piezoelectric layer; 40. Top electrode; 41. First portion of top electrode; 42. Second portion of top electrode; 50. Passivation layer; 501. First region; 502. Second region; 51. Window; 511. First window; 512. Second window; 60. Protective layer; 70. Pad area; 71. Pad; 200. Ultrasonic fingerprint module; 300. Electronic device. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of this application.

[0027] In related technologies, ultrasonic transducers are prone to having excessively large local thicknesses in the top electrode due to certain manufacturing processes. For example, Figure 1A A partial schematic diagram of an example ultrasonic transducer 100' fabricated using a printing process, showing the top electrode 40'. From Figure 1A As can be seen, the ultrasonic transducer 100' includes a substrate 10', a bottom electrode 20', a piezoelectric layer 30', a top electrode 40', and a protective layer 60'. The bottom electrode 20' includes multiple sub-electrodes 21' (also known as pixel electrodes). For example, taking the top electrode 40' as a silver layer, due to the influence of the printing process on the top electrode 40' of the silver layer, the thickness of the right edge region of the top electrode 40' of the ultrasonic transducer 100' is significantly greater than the thickness of other regions of the top electrode 40', forming a convex morphology. This results in the top electrode 40' being thicker above the sub-electrodes 21' at the edge of the AA region (Active Area, or effective detection area) of the ultrasonic transducer 100', typically 1µm to 5µm thicker than the top electrode 40' directly above the sub-electrodes 21' in the center region of the AA region.

[0028] For example, Figure 1B A top view schematic diagram of an example ultrasonic transducer 100' is shown. Figure 1B As can be seen in the image, the raised area of ​​the silver layer at the edge of the top electrode 40' (i.e., the area where the thickness of the top electrode 40' is relatively large) is located at the upper edge (here, "upper edge" refers to the area at the upper edge). Figure 1B Taking the top electrode 40' shown as an example, the remaining areas are basically of normal and uniform thickness, and the bottom electrode 20' of the ultrasonic transducer 100' includes multiple sub-electrodes 21' (also called pixel electrodes) arranged in an array on the upper surface of the substrate 10'.

[0029] For example, Figure 1C It shows Figure 1B The diagram illustrates the distribution of ultrasonic resonant frequencies in different regions of the ultrasonic transducer 100' in the example. Figure 1C As can be seen, the local ultrasonic resonant frequency of the edge silver layer protrusion area (that is, the area where the thickness of the top electrode 40' is relatively large) is lower than that of the local ultrasonic resonant frequency of the area where the silver layer is not protruding (that is, the area where the thickness of the top electrode 40' is normal).

[0030] For example, Figure 1D It shows Figure 1B The example shows the ultrasonic amplitude distribution in different regions of the ultrasonic transducer 100'. Figure 1DFrom left to right, the ultrasonic amplitudes are the raised areas of the silver layer at the top edge. From left to right, they correspond to the areas from the top edge to the bottom edge. It can be seen that the ultrasonic amplitude of the raised areas of the silver layer at the top edge (that is, the area where the thickness of the top electrode 40' is relatively large) is significantly higher than that of the area where the silver layer is not raised (that is, the area where the thickness of the top electrode 40' is normal).

[0031] Understandable, Figures 1A-1D The examples provided are for illustrative purposes only and are not intended to limit the scope of the embodiments described in this application. Figures 1A-1D As the example illustrates, the ultrasonic transducer is affected by certain fabrication processes of the top electrode, resulting in a localized increase in top electrode thickness. This can lead to a situation where the sub-electrode (also known as the pixel electrode) corresponding to the area with the larger top electrode thickness exhibits a lower ultrasonic resonant frequency and a larger ultrasonic amplitude compared to the sub-electrode corresponding to the area with normal top electrode thickness. This results in a lower local resonant frequency and poor uniformity of the ultrasonic amplitude, easily leading to localized non-uniformity in the detection data. Consequently, it affects the local quality of the subsequently obtained ultrasonic image, resulting in poor transducer performance. Therefore, this paper proposes some new ultrasonic transducer technical solutions to improve the performance of ultrasonic transducers.

[0032] The technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0033] According to a first aspect of the embodiments of this application, an ultrasonic transducer 100 is provided, with reference to... Figure 2 , Figure 3 , Figure 5 As shown, the ultrasonic transducer 100 may include: a substrate 10, a bottom electrode 20, a passivation layer 50, and a piezoelectric layer 30; the bottom electrode 20 includes a plurality of sub-electrodes 21 located on the upper surface of the substrate 10; the passivation layer 50 is provided with a plurality of corresponding opening portions 51; the piezoelectric layer 30 is located above the passivation layer 50 and is partially embedded in the plurality of opening portions 51; wherein, the plurality of sub-electrodes 21 include at least a first sub-electrode and a second sub-electrode, the first opening area of ​​the opening portion 51 corresponding to the first sub-electrode is larger than the second opening area of ​​the opening portion 51 corresponding to the second sub-electrode, and the second sub-electrode is closer to the edge of the target side of the bottom electrode 20 than the first sub-electrode.

[0034] Based on this, the ultrasonic transducer 100 in this embodiment of the application has a passivation layer 50 between the bottom electrode 20 and the piezoelectric layer 30, and the passivation layer 50 has a plurality of opening portions 51 corresponding to the positions of a plurality of sub-electrodes 21 of the bottom electrode 20. The piezoelectric layer 30 is located above the passivation layer 50 and is partially embedded in the plurality of opening portions 51. The plurality of sub-electrodes 21 include at least a first sub-electrode and a second sub-electrode. The first opening area of ​​the opening portion 51 corresponding to the first sub-electrode is larger than the second opening area of ​​the opening portion 51 corresponding to the second sub-electrode, and the second sub-electrode is closer to the edge of the target side of the bottom electrode 20 than the first sub-electrode. Therefore, in this embodiment, by making the opening area of ​​the passivation layer 50 corresponding to the second sub-electrode smaller than the opening area corresponding to the first sub-electrode, the piezoelectric layer 30 can be thinned relatively more above the second sub-electrode, which is closer to the target side of the bottom electrode 20, through the passivation layer 50. In this way, by thinning the piezoelectric layer more, the performance deviation of the local resonant frequency at the second sub-electrode and the first sub-electrode caused by the edge effect of the ultrasonic transducer electrode structure can be specifically compensated to a certain extent, thereby improving the potentially low local resonant frequency. This can further improve the uniformity of the local resonant frequency at the first and second sub-electrodes, effectively improve the uniformity of the ultrasonic amplitude at the second and first sub-electrodes, and improve the local uniformity of the detection data at both locations. This is beneficial to improving the local quality of the subsequently obtained ultrasonic image, thereby improving the performance of the ultrasonic transducer 100.

[0035] In some alternative embodiments, the edge of the target side of the bottom electrode 20 may be the edge of the side closer to the thicker region of the top electrode 40.

[0036] In some alternative embodiments, refer to Figure 2 , Figure 3 , Figure 5As shown, the ultrasonic transducer 100 may include: a substrate 10, a bottom electrode 20, a passivation layer 50, a piezoelectric layer 30, and a top electrode 40; the bottom electrode 20 includes a plurality of sub-electrodes 21 located on the upper surface of the substrate 10; the passivation layer 50 is located above the substrate 10 and partially covers the bottom electrode 20, and the passivation layer 50 is provided with a plurality of openings 51 corresponding to the positions of the plurality of sub-electrodes 21; the piezoelectric layer 30 is located above the passivation layer 50 and is partially embedded in the plurality of openings 51; the top electrode 40 is at least partially located above the piezoelectric layer 30. Among them, the plurality of sub-electrodes 21 include at least a first sub-electrode and a second sub-electrode, and the top electrode 40 includes a first part top electrode and a second part top electrode. The vertical projection of the first sub-electrode toward the substrate 10 coincides with the vertical projection of the first part top electrode toward the substrate 10, and the vertical projection of the second sub-electrode toward the substrate 10 coincides with the vertical projection of the second part top electrode toward the substrate 10. The maximum thickness of the first part top electrode is less than the maximum thickness of the second part top electrode. The first opening area of ​​the opening portion 51 corresponding to the first sub-electrode is greater than the second opening area of ​​the opening portion 51 corresponding to the second sub-electrode.

[0037] Optionally, the second sub-electrode is closer to the edge of the target side of the bottom electrode 20 than the first sub-electrode.

[0038] Based on this, the ultrasonic transducer 100 in this embodiment of the application has a passivation layer 50 between the bottom electrode 20 and the piezoelectric layer 30, and the passivation layer 50 has a plurality of opening portions 51 corresponding to the positions of a plurality of sub-electrodes 21 of the bottom electrode 20. The piezoelectric layer 30 is located above the passivation layer 50 and is partially embedded in the plurality of opening portions 51. The plurality of sub-electrodes 21 include at least a first sub-electrode and a second sub-electrode. The top electrode 40 includes a first part top electrode and a second part top electrode. The maximum thickness of the first part top electrode is less than the maximum thickness of the second part top electrode. The first opening area of ​​the opening portion 51 corresponding to the first sub-electrode is greater than the second opening area of ​​the opening portion 51 corresponding to the second sub-electrode. It is understandable that, since the maximum thickness of the first part of the top electrode is less than the maximum thickness of the second part of the top electrode, if no processing is performed, the local resonant frequency at the second sub-electrode in the ultrasonic transducer will be lower than that at the first sub-electrode, resulting in poor uniformity of ultrasonic amplitude at the second and first sub-electrodes. This can easily lead to local non-uniformity of the detection data at the two locations, affecting the local quality of the subsequently obtained ultrasonic image. In this embodiment, by setting a passivation layer 50 and making the first window area of ​​the passivation layer 50 corresponding to the first sub-electrode larger than the second window area of ​​the passivation layer 50 corresponding to the second sub-electrode, a larger portion of the piezoelectric layer 30 above the second sub-electrode can be thinned by the passivation layer 50 compared to the piezoelectric layer 30 above the first sub-electrode. This allows for a greater reduction in the piezoelectric layer 30, thereby increasing the local resonant frequency at the second sub-electrode in the ultrasonic transducer 100. This improves the local resonant frequency compensation effect caused by the thicker top electrode at the second part, resulting in better uniformity of the local resonant frequencies at the first and second sub-electrodes. This effectively improves the uniformity of the ultrasonic amplitude at both sub-electrodes and enhances the local uniformity of the detection data at both locations. This is beneficial for improving the local quality of the subsequently obtained ultrasonic image, thus significantly improving the performance of the ultrasonic transducer 100.

[0039] First, to facilitate the explanation of the embodiments of this application, let's first combine... Figure 3 Explanation of descriptions such as "the vertical projection of the first sub-electrode toward the substrate 10 coincides with the vertical projection of the first part of the top electrode toward the substrate 10" and "the vertical projection of the second sub-electrode toward the substrate 10 coincides with the vertical projection of the second part of the top electrode toward the substrate 10": like Figure 3 As shown, it illustrates Figure 2 A magnified view of a portion of point T in the middle, assuming we take... Figure 3The sub-electrodes 21 on the left and right sides within the two dotted lines are the first sub-electrode 211 and the second sub-electrode 212, respectively. These two dotted lines simultaneously indicate the vertical projection area, showing the first portion of the top electrode 41 corresponding to the first sub-electrode 211 and the second portion of the top electrode 42 corresponding to the second sub-electrode 212 within the two dotted lines. The vertical projection of the first portion of the top electrode 41 toward the substrate 10 coincides with the vertical projection of the first sub-electrode 211 toward the substrate 10, and the vertical projection of the second portion of the top electrode 42 toward the substrate 10 coincides with the vertical projection of the second sub-electrode 212 toward the substrate 10. Figure 3 As can be seen, the maximum thickness of the first part, top electrode 41, is less than the maximum thickness of the second part, top electrode 42. Figure 3 As can be seen, the first window area of ​​the passivation layer 50 corresponding to the first sub-electrode 211 (or the first window 511) is greater than the second window area of ​​the passivation layer 50 corresponding to the second sub-electrode 212 (or the second window 512).

[0040] Furthermore, for ease of understanding of the following embodiments, Figure 3 The first portion of the piezoelectric layer 31 and the second portion of the piezoelectric layer 32 are also shown. (See figure) Figure 3 Within the two dashed areas, the vertical projections of the first piezoelectric layer 31 toward the substrate 10, the first top electrode 41 toward the substrate 10, and the first sub-electrode 211 toward the substrate 10 overlap. Similarly, the vertical projections of the second piezoelectric layer 32 toward the substrate 10, the second top electrode 42 toward the substrate 10, and the second sub-electrode 212 toward the substrate 10 overlap. It can be seen that because the first window area of ​​the first window portion 511 corresponding to the first sub-electrode 211 is larger than the second window area of ​​the second window portion 512 corresponding to the second sub-electrode 212, the passivation layer 50 achieves a greater reduction in the thickness of the second piezoelectric layer 32 compared to the first piezoelectric layer 31, resulting in a larger volume of the first piezoelectric layer 31 than the second piezoelectric layer 32.

[0041] Therefore, in conjunction with the above description, the beneficial effects of the technical solution of the embodiments of this application can be easily understood: In the embodiments of this application, by setting a passivation layer 50, and making the first window area of ​​the window portion 51 (i.e., the first window portion 511) of the passivation layer 50 corresponding to the first sub-electrode 211 larger than the second window area of ​​the window portion 51 (i.e., the second window portion 512) of the passivation layer 50 corresponding to the second sub-electrode 212, compared with the piezoelectric layer (i.e., the first part of the piezoelectric layer 31) above the first sub-electrode 211, the passivation layer 50 can achieve thinning of more of the piezoelectric layer (i.e., the second part of the piezoelectric layer 32) above the second sub-electrode 212. In this way, by thinning the piezoelectric layer more, the local resonant frequency at the second sub-electrode 212 in the ultrasonic transducer 100 can be increased to a certain extent, thereby improving the local resonant frequency at the second sub-electrode 212 caused by the thickness of the second part of the top electrode 42, achieving the effect of local resonant frequency compensation, and thus making the first sub-electrode 211 (for example, referring to...) Figure 3 (understand the range of the dotted line on the left) and the second sub-electrode 212 (for example, refer to...) Figure 3 The uniformity of the local resonant frequency (understood by the dotted line on the right) is better, which effectively improves the uniformity of the ultrasonic amplitude at the second sub-electrode 212 and the first sub-electrode 211, and improves the local uniformity of the detection data at the two locations. This is beneficial to improving the local quality of the subsequently obtained ultrasonic image, thereby improving the performance of the ultrasonic transducer 100.

[0042] To summarize the above process simply: a thicker top electrode leads to a lower resonant frequency, which in turn leads to the use of a passivation layer and a reduction in the window area, while the piezoelectric layer is thinned, resulting in a higher resonant frequency. This positive and negative process can compensate for the shift in the resonant frequency.

[0043] Understandable Figure 3 The examples provided are for illustrative purposes only and are not intended to limit the scope of this application.

[0044] It should be noted that the first part top electrode, the second part top electrode, the first part piezoelectric layer, the second part piezoelectric layer, the target part top electrode, etc., mentioned in the embodiments of this application are all the parts of the top electrode 40 or the piezoelectric layer 30 along the thickness direction in the corresponding region.

[0045] Optionally, substrate 10 can be a silicon-based substrate. Alternatively, it can be any type of substrate, including but not limited to glass substrates, PET (Polyethylene Terephthalate) substrates, or PI (Polyimide) substrates, as long as it meets the requirements.

[0046] Optionally, the bottom electrode 20 can be made of any material, such as metal or other conductive materials, without limitation. For example, the bottom electrode 20 can be a copper electrode. The bottom electrode 20 may include a plurality of sub-electrodes 21 located on the upper surface of the substrate 10, each sub-electrode 21 can be regarded as a "pixel", therefore, in this embodiment, the sub-electrode 21 can also be called a "pixel electrode". Optionally, the plurality of sub-electrodes 21 can be arranged in an array on the upper surface of the substrate 10, that is, arranged in multiple rows and columns. When fabricating the ultrasonic transducer 100, the bottom electrode 20 can be fabricated using any feasible process, including but not limited to deposition process, etching process, electroplating process, etc.

[0047] Optionally, the piezoelectric layer 30 can generate and receive ultrasonic signals based on the piezoelectric effect. Optionally, the piezoelectric layer 30 can include any piezoelectric material. For example, it can include, but is not limited to, at least one of PVDF (polyvinylidene difluoride), lead zirconate titanate, and lithium niobate. PVDF material can include PVDF, PVDF copolymers, etc. In fabricating the ultrasonic transducer 100, the piezoelectric layer 30 can be formed on the substrate 10 in any suitable manner, without particular limitation. For example, it can be achieved by methods including but not limited to coating, screen printing, dry film lamination, etc., or by physical or chemical vapor deposition methods such as sputtering and evaporation.

[0048] Optionally, the top electrode 40 can be made of any material, such as metal or other conductive materials, without limitation. For example, the top electrode 40 can be a silver electrode. The top electrode 40 can be fabricated using any feasible process, including but not limited to post-sputtering etching, deposition processes, electroplating processes, etc. In some embodiments, the top electrode 40 can be fabricated by a printing process. As described in the examples above, the effects of the printing process, including but not limited to, can lead to uneven thickness of the top electrode 40. For example, using a printing process, the fabricated top electrode 40 may have some edge areas that are thicker than other areas, forming a raised morphology (which can be combined with...). Figure 2 , Figure 3 , Figure 5 (To understand).

[0049] Optionally, in the ultrasonic transducer 100, an excitation signal can be applied to the top electrode 40 to create an electric field between the top electrode 40 and the bottom electrode 20 (i.e., a voltage difference is formed on both sides of the piezoelectric layer 30 in the thickness direction), thereby exciting the piezoelectric layer 30 to emit ultrasonic signals. Optionally, the excitation signal can be a pulsed excitation signal, such as a pulsed voltage signal. Optionally, the excitation signal can be input from an external circuit, and by applying the excitation signal to the top electrode 40, the top electrode 40 can excite the piezoelectric layer 30 to emit ultrasonic signals outward.

[0050] Optionally, the bottom electrode 20 can receive the ultrasonic detection signal generated between the top electrode 40 and the bottom electrode 20 when the returned ultrasonic signal acts on the piezoelectric layer 30. The ultrasonic detection signal can be used to generate an ultrasonic image. Each sub-electrode 21 of the bottom electrode 20 can receive a portion of the ultrasonic detection signal for generating an ultrasonic image.

[0051] Specifically, after the top electrode 40 is excited by an excitation signal, an electric field is formed between it and the bottom electrode 20, and a voltage difference is formed on both sides of the piezoelectric layer 30 in the thickness direction, thereby exciting the piezoelectric layer 30 to vibrate and emit ultrasonic signals. In this process, the piezoelectric layer 30 converts the electrical signal into an ultrasonic signal (i.e., mechanical vibration) based on the piezoelectric effect. The bottom electrode 20 can receive the ultrasonic detection signal (electric signal) obtained by the ultrasonic signal converted and returned by the piezoelectric layer 30.

[0052] Optionally, the ultrasonic detection signal received by the bottom electrode 20 can be used to realize ultrasonic biometric detection (such as ultrasonic fingerprint detection). Optionally, the ultrasonic detection signal can be used to generate an ultrasonic image, and ultrasonic biometric detection can be realized based on the ultrasonic image. For example, taking ultrasonic fingerprint detection as an example, the ultrasonic detection signal can be used to generate an ultrasonic fingerprint image, and fingerprint detection can be performed based on the ultrasonic fingerprint image.

[0053] Optionally, the process of generating an ultrasonic image (such as an ultrasonic fingerprint image) and performing detection (such as fingerprint detection) based on the ultrasonic image (such as an ultrasonic fingerprint image) can be implemented by a controller in an electronic device on which the ultrasonic transducer 100 is installed (which can be electrically connected to the ultrasonic transducer 100); or, in other optional embodiments, the process of generating an ultrasonic image (such as an ultrasonic fingerprint image) can also be implemented by a processing unit in the ultrasonic transducer 100, which sends the generated ultrasonic image (such as an ultrasonic fingerprint image) to the controller in the electronic device, and the controller then performs detection (such as fingerprint detection) based on the ultrasonic image (such as an ultrasonic fingerprint image).

[0054] In some alternative embodiments, refer to Figure 2 , Figure 3 , Figure 5As shown, the ultrasonic transducer 100 may further include a protective layer 60, which covers at least a portion of the top electrode 40. Thus, the protective layer 60 can protect at least a portion of the top electrode 40, for example, preventing water and oxygen corrosion and other adverse environmental factors, thereby improving the lifespan of the ultrasonic transducer 100. Optionally, the protective layer 60 can completely cover the top electrode 40 to better protect the ultrasonic transducer 100, preventing water and oxygen corrosion and other adverse environmental factors, and improving the lifespan of the ultrasonic transducer 100.

[0055] Optionally, the protective layer 60 can be an insulating layer, made of any material. For example, it can be a protective layer made of inorganic insulating materials such as silicon oxide and silicon nitride, or it can be a protective layer made of organic insulating materials such as polyimide and epoxy resin. The choice can be made according to actual needs, and no specific restrictions are imposed here.

[0056] Optionally, the protective layer 60 can be prepared in any feasible manner, without limitation. For example, it can be prepared by screen printing or exposure and development. Alternatively, it can be prepared by coating or dry film lamination.

[0057] In this embodiment, a passivation layer 50 is provided. When fabricating the ultrasonic transducer 100, the passivation layer 50 can be fabricated on top of the substrate 10 after the bottom electrode 20 is fabricated. Multiple openings 51 in the passivation layer 50 can be formed by etching. These openings (or simply openings) can expose multiple sub-electrodes 21 of the bottom electrode 20, allowing the piezoelectric layer 30 to contact and connect with the multiple sub-electrodes 21 of the bottom electrode 20 through the multiple openings 51 during subsequent fabrication. Since the passivation layer 50 itself has a certain thickness, some portions of the piezoelectric layer 30 can be thinned by adjusting the size of the opening area of ​​the openings 51.

[0058] For example, when preparing the passivation layer 50, a whole layer of passivation layer material can be covered on the substrate 10, which includes the bottom electrode 20, and then the part of the whole layer of passivation layer material that needs to expose multiple sub-electrodes 21 can be etched to expose multiple sub-electrodes 21. The opening obtained by etching on the passivation layer 50 forms multiple opening portions 51.

[0059] Optionally, the passivation layer 50 may be an insulating layer. The insulating material may be, for example, an inorganic insulating material including but not limited to silicon oxide, silicon nitride, etc., or an organic insulating material including but not limited to polyimide, epoxy resin, etc. The choice can be made according to actual needs, and no specific restrictions are imposed here.

[0060] Typically, in the embodiments of this application, the passivation layer 50 has a relatively small impact on the ultrasonic resonant frequency and ultrasonic transmission compared to the piezoelectric layer 30 and the top electrode 40 of the same thickness, and can be basically ignored.

[0061] It should be noted that, for the evidence collection of the technical solutions of the embodiments of this application, as long as a first sub-electrode and a second sub-electrode that meet the conditions can be found in the bottom electrode of an ultrasonic transducer of a certain competitor, that is, the maximum thickness of the first part of the top electrode corresponding to the first sub-electrode is less than the maximum thickness of the second part of the top electrode corresponding to the second sub-electrode, and the first opening area of ​​the opening part corresponding to the first sub-electrode is greater than the second opening area of ​​the opening part corresponding to the second sub-electrode, should be regarded as being covered within the protection scope of the embodiments of this application.

[0062] Optionally, in the passivation layer 50 of this application embodiment, the window portion 51 corresponding to the position of the sub-electrode 21 may include: all the windows whose vertical projection toward the sub-electrode 21 is located on the sub-electrode 21.

[0063] Based on this, in the embodiments of this application, the window portion 51 corresponding to the position of the sub-electrode 21 may include all the windows whose vertical projection toward the sub-electrode 21 is located on the sub-electrode 21. This accurately defines the correspondence between the window portion 51 and the sub-electrode 21, and also allows the window portion 51 to be flexibly designed into a suitable style as needed without affecting the calculation of the window area of ​​the window portion 51. This can improve the design flexibility of the ultrasonic transducer 100 so as to meet various user needs and usage requirements.

[0064] Optionally, any one of the windows in the windowed portion 51 can be a complete window, that is, the vertical projection of the window toward the sub-electrode 21 is 100% located on the sub-electrode 21. This allows the passivation layer 50 to surround the edge of the sub-electrode 21, thereby improving the reliability of the sub-electrode 21.

[0065] In this embodiment, the piezoelectric layer 30 may be partially embedded in a plurality of window portions 51. For example, in some optional embodiments, refer to Figure 2 , Figure 3 , Figure 5 As shown, the piezoelectric layer 30 can be partially embedded in multiple window portions 51 and in contact with multiple sub-electrodes 21. Thus, the piezoelectric layer 30 can be partially embedded in multiple window portions 51 to achieve direct contact with multiple sub-electrodes 21. This structure results in low contact resistance between the piezoelectric layer 30 and the sub-electrodes 21, allowing the electric field to be applied more effectively to the piezoelectric layer 30. Consequently, the ultrasonic transducer 100 exhibits better electrical performance, higher electrical signal transmission efficiency, and lower signal delay and distortion.

[0066] For example, the piezoelectric layer 30 is partially embedded in multiple windowed portions, and the piezoelectric layer 30 contacts multiple sub-electrodes 21 through an adhesive layer. Thus, the piezoelectric layer 30 forms contact with the multiple sub-electrodes 21 through the adhesive layer, which can greatly improve the bonding force between the piezoelectric layer 30 and the sub-electrodes 21. Furthermore, due to the presence of the adhesive layer, the piezoelectric layer 30 and the sub-electrodes 21 do not need to be in direct contact, thereby reducing the required roughness of the contact surfaces between the piezoelectric layer 30 and the sub-electrodes 21 and lowering the manufacturing complexity.

[0067] Optionally, the adhesive layer may only cover the multiple sub-electrodes 21. Alternatively, the adhesive layer may cover at least part of the passivation layer 50 in addition to covering the multiple sub-electrodes 21. Optionally, the adhesive layer may be an insulating adhesive layer or a conductive adhesive layer. Optionally, the thickness of the adhesive layer may be less than 1 μm, and the specific thickness can be selected as needed (e.g., including but not limited to 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, etc.). An adhesive layer with a thickness of less than 1 μm can improve the bonding force between the piezoelectric layer 30 and the sub-electrodes 21, and can also better enable the ultrasonic transducer 100 to have better electrical performance and electrical signal transmission efficiency, as well as lower signal delay and distortion.

[0068] In the passivation layer 50 of this application embodiment, each window portion 51 may include one or more windows. In some optional embodiments, the multiple window portions 51 include at least one of a first type of window portion and a second type of window portion, wherein: the first type of window portion includes a single window; and the second type of window portion includes a combination of multiple windows.

[0069] For example, Figure 6 The diagram shows a schematic of the window portion 51 corresponding to some of the sub-electrodes 21. Combined with... Figure 6 As shown, the examples shown in subfigures a and b are all single windows, that is, they are all first type of window openings; the examples shown in subfigures c, d and e are all combinations of multiple windows, that is, they are all second type of window openings.

[0070] For example, in some ultrasonic sensors, each window portion 51 can be designed as a single window; or, multiple window portions 51 can be designed as a single window, and other multiple window portions 51 can be designed as a combination of multiple windows; or, each window portion 51 can be designed as a combination of multiple windows. The choice can be made as needed, and there is no unique limitation in this embodiment.

[0071] It should be understood that, in the embodiments of this application, the window opening 51 can be designed as a first type of window opening with a single window or a second type of window opening with a combination of multiple windows, as needed. This can improve the design flexibility of the ultrasonic transducer 100, so as to meet various user needs and usage requirements. Furthermore, it also facilitates a more flexible design of the window opening area of ​​the window opening 51.

[0072] In this embodiment, the shape of the windows included in the window opening portion 51 is not specifically limited; each window can be a regular shape or an irregular shape. For example, taking a single window as an example, it can be a regular shape, such as including but not limited to rectangles (including squares), circles, triangles, regular hexagons, etc., or it can be an irregular shape, such as including but not limited to crescent shapes, wavy shapes, etc., and can be designed as needed. For example, as Figure 6 As shown, subfigures a and b illustrate examples of the opening portion 51 of a single rectangular opening.

[0073] For example, taking a combination of multiple windows as an example, each window can be a regular or irregular shape, and the multiple windows can be arranged in any way. The sizes of the multiple windows can be the same or different. For example, it can be multiple rectangular windows arranged in an array (e.g., such as...). Figure 6 As shown, subfigure c shows an example of multiple rectangular windows of the same size arranged in a 2x2 array, subfigure d shows an example of multiple rectangular windows of the same size arranged in a 3x3 array, and subfigure e shows an example of multiple rectangular windows of the same size arranged in a 4x4 array.

[0074] In some alternative embodiments, refer to Figure 6 As shown in sub-figures a and b, the window portion 51 includes a single rectangular (or circular, or other shape with a center) window. The center point of this single rectangular window can coincide with the center point of the corresponding sub-electrode 21, allowing the window portion 51 to expose the central region of the sub-electrode 21 to contact the piezoelectric layer 30. In some optional embodiments, refer to... Figure 6 As shown in sub-figures c, b, and b, the window portion 51 includes multiple rectangular windows of the same size arranged in an array. The center of the smallest outer rectangle of the multiple rectangular windows can coincide with the center of the sub-electrode 21, so that the window portion 51 can expose the sub-electrode 21 relatively uniformly through the multiple rectangular windows to contact the piezoelectric layer 30.

[0075] In some alternative embodiments, refer to Figure 4As shown, in the ultrasonic transducer 100 of this application embodiment, a plurality of sub-electrodes 21 are arranged in N rows along the first direction F on the upper surface of the substrate 10, where N≥2 and N is an integer; the passivation layer 50 includes a first region 501 and a second region 502. The first region 501 includes P-row window portions 51 corresponding to P rows of sub-electrodes 21, and the second region 502 includes Q-row window portions 51 corresponding to Q rows of sub-electrodes 21. The Q-row sub-electrodes 21 and the P-row sub-electrodes are different rows of sub-electrodes 21 in the N rows of sub-electrodes 21, where P≥1, Q≥1, and P and Q are both integers; wherein, the opening area of ​​each window portion 51 in the first region 501 is greater than the opening area of ​​each window portion 51 in the second region 502; the P-row sub-electrodes 21 include a first sub-electrode, and the Q-row sub-electrodes 21 include a second sub-electrode.

[0076] Optionally, the passivation layer 50 can be divided into regions in this application, for example, into a first region 501 and a second region 502. Figure 4 As shown, the thicker region of the passivation layer 50 relative to the top electrode 40 can be divided into the second region 502, while the normal region with uniform thickness of the top electrode 40 can be divided into the first region 501. For example, the region can be divided according to the N rows of sub-electrodes 21 of the ultrasonic transducer 100. For example, the first region 501 and the second region 502 can be divided according to experience with the fabrication process of the top electrode 40. For example, taking the fabrication process of the top electrode 40 as an example, if, according to experience, the commonly used printing process will cause the top electrode 40 above the 5 rows of sub-electrodes 21 on one side edge to be thicker, then Q can be 5, and the passivation layer 50 region corresponding to the Q=5 row of sub-electrodes 21 can be divided into the second region 502, while the passivation layer 50 regions corresponding to other rows of sub-electrodes 21 (e.g., P rows of sub-electrodes 21) can be divided into the first region 501. Subsequently, when opening windows in the passivation layer, the opening area of ​​each window portion 51 in the first region 501 can be larger than the opening area of ​​each window portion 51 in the second region 502. In this way, the first sub-electrode of the plurality of sub-electrodes 21 of the ultrasonic transducer 100 can be taken from the P row sub-electrodes 21 corresponding to the first region 501, and the second sub-electrode can be taken from the Q row sub-electrodes 21 corresponding to the second region 502.

[0077] Based on this, since the passivation layer 50 in this application includes a first region 501 and a second region 502, and the first region 501 includes P-row window portions 51 corresponding to P-row sub-electrodes 21, and the second region 502 includes Q-row window portions 51 corresponding to Q-row sub-electrodes 21, and the opening area of ​​each window portion 51 in the first region 501 is larger than the opening area of ​​each window portion 51 in the second region 502, the ultrasonic transducer 100 can better reduce the adverse effects of the excessive local thickness of the top electrode 40 caused by the fabrication process of the top electrode 40, and can better achieve thinning of more of the piezoelectric layer 30 in the thicker area of ​​the top electrode 40 through the passivation layer 50. In this way, more of the piezoelectric layer 30 can be thinned. The layer, to a certain extent, improves the local resonant frequency at the point where the top electrode 40 in the ultrasonic transducer 100 is thicker, thereby improving the low local resonant frequency caused by the thickness of the top electrode 40, achieving the effect of local resonant frequency compensation. This can at least improve the uniformity of the local resonant frequency at the first sub-electrode in the P row sub-electrode corresponding to the first region 501 and the second sub-electrode in the Q row sub-electrode corresponding to the second region 502, effectively improving the uniformity of the ultrasonic amplitude at the first and second sub-electrodes and improving the local uniformity of the detection data at the two locations. This is beneficial to improving the local quality of the subsequently obtained ultrasonic image, thereby significantly improving the performance of the ultrasonic transducer 100.

[0078] In some optional embodiments, the P-row sub-electrode 21 can be the first P-row sub-electrode, and the Q-row sub-electrode 21 can be the second Q-row sub-electrode.

[0079] It should be noted that the N rows of sub-electrodes 21 formed by multiple sub-electrodes 21 in this application can be configured in multiple rows according to the actual needs of the ultrasonic transducer 100, and each row of sub-electrodes 21 can be the same or different. For example, in Figure 4 In the example shown, each row of sub-electrodes 21 is identical, and multiple sub-electrodes 21 are arranged in N rows along a first direction F and in multiple columns along another direction perpendicular to the first direction F, forming an array of multiple sub-electrodes 21.

[0080] For example, Figure 4 In the example, N=22 rows, P=17 rows, Q=5 rows, and the multiple sub-electrodes 21 of the bottom electrode 20 are arranged in 22 rows along the first direction F on the upper surface of the substrate 10. The first region 501 has 17 rows of window portions 51 corresponding to the 17 rows of sub-electrodes, and the second region 502 has 5 rows of window portions 51 corresponding to the 5 rows of sub-electrodes. It should be understood that... Figure 4 The examples in this application are merely illustrative and are not intended to limit the scope of the embodiments described herein.

[0081] For example, Figure 2 and Figure 5In the examples, N=16 rows, P=11 rows, Q=5 rows, and the multiple sub-electrodes 21 of the bottom electrode 20 are arranged in 16 rows along the first direction F on the upper surface of the substrate 10. The first region 501 has 11 rows of window portions 51 corresponding to the 11 rows of sub-electrodes, and the second region 502 has 5 rows of window portions 51 corresponding to the 5 rows of sub-electrodes. It should be understood that... Figure 2 and Figure 5 The examples provided are merely for illustrative purposes and are not intended to limit the scope of the embodiments described in this application.

[0082] In some alternative embodiments, P+Q=N, P row sub-electrodes 21 are arranged adjacently along the first direction F, Q row sub-electrodes are arranged adjacently along the first direction F, and the first region 501 and the second region 502 are arranged adjacently along the first direction F, or the first region 501 and the second region 502 are arranged adjacently in the opposite direction of the first direction F.

[0083] Therefore, the second region 502 of the passivation layer 50 can be located in the edge region, thus better adapting to the thinning requirements of the piezoelectric layer 30 in the thicker edge region of the top electrode 40. This allows the ultrasonic transducer 100 to better reduce the adverse effects of the localized excessive thickness at the edge of the top electrode 40 caused by the fabrication process (such as printing process) of the top electrode 40. It can better achieve thinning of more of the piezoelectric layer 30 in the thicker edge region of the top electrode 40 through the passivation layer 50. In this way, by thinning the piezoelectric layer more, the thickness of the locally thicker edge region of the top electrode 40 in the ultrasonic transducer 100 can be improved to a certain extent. The local resonant frequency is increased, thereby improving the low local resonant frequency caused by the excessive thickness of the local top electrode 40, achieving the effect of local resonant frequency compensation. This can at least improve the uniformity of the local resonant frequency at the first sub-electrode in the P row sub-electrode corresponding to the first region 501 and the second sub-electrode in the Q row sub-electrode corresponding to the second region 502, effectively improving the uniformity of the ultrasonic amplitude at the first and second sub-electrodes and improving the local uniformity of the detection data at the two locations. This is beneficial to improving the local quality of the subsequently obtained ultrasonic image, thereby significantly improving the performance of the ultrasonic transducer 100.

[0084] For example, such as Figure 4 As shown, N=22, P=17 rows, Q=5 rows, then it can be seen that P+Q=N. The sub-electrodes 21 in row P=17 corresponding to the first region 501 are arranged adjacently along the first direction F. The sub-electrodes 21 in row Q=5 corresponding to the second region 502 are arranged adjacently along the first direction F. Furthermore, the first region 501 and the second region 502 are arranged adjacently along the first direction F. The arrangement of row P=17 and row Q=5 sub-electrodes 21 along the first direction F ensures that the sub-electrodes 21 in row Q=5 corresponding to the second region 502 are located... Figure 4If the edge of the top electrode 40 is thicker, then the second region 502 can be located in the edge region (near the top electrode 40). Figure 4 The upper edge region is used to accommodate the thinning requirements of the piezoelectric layer 30 under the thicker edge region of the top electrode 40. Optionally, if the P=17 row sub-electrode 21 and the Q=5 row sub-electrode 21 are arranged adjacent to each other in the opposite direction of the first direction F, the second region 502 can still be located in the edge region (e.g., near the edge region). Figure 4 The upper edge region can also be adapted to the thinning requirements of the piezoelectric layer 30, which is thicker on the lower edge of the top electrode 40 due to the fabrication process of the top electrode 40 (such as printing process).

[0085] For example, such as Figure 2 or Figure 5 As shown, N=16 rows, P=11 rows, and Q=5 rows. Therefore, P+Q=N. The sub-electrodes 21 in row P=11 corresponding to the first region 501 are arranged adjacently along the first direction F. The sub-electrodes 21 in row Q=5 corresponding to the second region 502 are also arranged adjacently along the first direction F. Furthermore, the first region 501 and the second region 502 are arranged adjacently along the first direction F. The arrangement of sub-electrodes 21 in row P=11 and row Q=5 along the first direction F ensures that the sub-electrodes 21 in row Q=5 corresponding to the second region 502 are located in... Figure 2 or Figure 5 If the edge of the top electrode 40 is thicker, then the second region 502 can be located in the edge region (e.g., near the edge). Figure 2 or Figure 5 The right edge region is used to accommodate the thinning requirements of the piezoelectric layer 30 under the thicker edge region of the top electrode 40. Optionally, if the P=11 row sub-electrode 21 and the Q=5 row sub-electrode 21 are arranged adjacent to each other in the opposite direction of the first direction F, the second region 502 can still be located in the edge region (e.g., near the edge region). Figure 2 or Figure 5 The left edge region can also be used to adapt to the thinning requirements of the piezoelectric layer 30, which is thicker on the lower edge of the top electrode 40 due to the fabrication process of the top electrode 40 (such as printing process).

[0086] In some alternative embodiments, such as Figure 4 As shown, the ultrasonic transducer 100 also includes a pad area 70, which is used for electrical connection between the ultrasonic transducer 100 and external circuitry. Optionally, as... Figure 4 As shown, the pad area 70 can be disposed on the substrate 10. The pad area 70 may include one or more pads 71. The pads 71 ​​can serve as the output / output port of the ultrasonic transducer 100 and are used for the electrical connection between the ultrasonic transducer 100 and external circuitry. Optionally, as shown... Figure 4As shown, along the first direction F1, the second region 502 is located between the first region 501 and the pad area 70, or the first region 501 is located between the second region 502 and the pad area 70.

[0087] To facilitate connection with external circuits, the pad area 70 of the ultrasonic transducer 100 can be located in the region near the edge of the substrate 10. In the above-mentioned optional structure in this application, along the first direction F1, the second region 502 is located between the first region 501 and the pad area 70, or the first region 501 is located between the second region 502 and the pad area 70. This allows the second region 502 of the passivation layer 50 to be located in the edge region, thereby better adapting to the thinning requirements of the piezoelectric layer 30 under the thicker edge region of the top electrode 40. This makes the ultrasonic transducer 100 more able to reduce the adverse effects of the localized thicker edge of the top electrode 40 caused by the fabrication process of the top electrode 40 (such as printing process), and can better achieve thinning of more of the piezoelectric layer 30 in the thicker edge region of the top electrode 40 through the passivation layer 50, thereby facilitating better improvement of the performance of the ultrasonic transducer 100.

[0088] Optionally, since the thickness of each part of the top electrode 40 corresponding to the first region 501 can be uniform, the opening area of ​​each opening portion 51 in the first region 501 can be made as large as possible as needed. For example, the opening area of ​​the opening portion 51 can be set to expose 95% of the sub-electrode 21 (for example, assuming the area of ​​the sub-electrode 21 is 100 units, the opening area can be 95 units).

[0089] In some optional embodiments, within the first region 501, the opening area of ​​each window portion 51 in at least one row of window portions 51 deviates from the average opening area of ​​each window portion 51 by no more than ±2.5%. That is, within the first region 501, the opening area of ​​each window portion 51 in at least one row of window portions 51 is within the range of 97.5% to 102.5% of the average opening area of ​​each window portion 51.

[0090] To facilitate windowing of the passivation layer 50 within the first region 501, the windowing areas of at least one row of windowed portions 51 within the first region 501 can be set to the same area. However, due to errors in the fabrication process, it is difficult to guarantee that they are completely identical. Therefore, in this application, the deviation between the windowing area of ​​each windowed portion 51 in at least one row of windowed portions 51 within the first region 501 and the average windowing area of ​​each windowed portion 51 does not exceed ±2.5%. Since a certain fluctuation range is allowed, the process accuracy requirement is reduced, the cost of the windowing process is lower, and the difference in the windowing area of ​​at least one row of windowed portions 51 within the first region 501 is sufficiently small, so the windowing areas can be considered to be basically the same. In this case, it is convenient to window the first region 501 of the passivation layer 50 during fabrication, and the windowing areas of the same row of windowed portions 51 can be basically the same, thereby making the resonant frequency and ultrasonic amplitude uniform at at least one row of sub-electrodes 21 corresponding to the first region 501 uniform, so as to improve the local quality of the subsequently obtained ultrasonic image and improve the performance of the ultrasonic transducer.

[0091] For example, assuming that the average window area of ​​each window 51 in a certain row of window 51 in the first region 501 is 100 units, then the window area of ​​each window 51 in that row of window 51 can be within the range of 100×(1±2.5%) units, that is, 97.5~102.5 units.

[0092] Optionally, within the first region 501, the deviation between the opening area of ​​each window portion 51 in each row of window portions 51 and the average opening area of ​​each window portion 51 does not exceed ±2.5%. Therefore, this structure, by allowing a certain range of fluctuation, reduces the precision requirements of the manufacturing process and lowers the cost of the windowing process. This structure allows for convenient windowing of the first region 501 of the passivation layer 50 during fabrication, and the opening areas of each row of window portions 51 can be substantially the same. This results in uniform resonant frequency and ultrasonic amplitude at each row of sub-electrodes 21 corresponding to the first region 501, thereby improving the local quality of the subsequently obtained ultrasonic image and enhancing the performance of the ultrasonic transducer.

[0093] Optionally, within the first region 501, the deviation between the opening area of ​​each window portion 51 and the average opening area of ​​each window portion 51 does not exceed ±2.5%. Therefore, this structure requires lower precision in fabrication and reduces the cost of opening windows in the first region 501 of the passivation layer 50. The opening areas of each window portion 51 can be substantially the same, resulting in uniform resonant frequencies and ultrasonic amplitudes at each sub-electrode 21 corresponding to the first region 501. This improves the local quality of the subsequently obtained ultrasonic image and enhances the performance of the ultrasonic transducer.

[0094] In some optional embodiments, within the second region 502, the opening area of ​​each window portion 51 in at least one row of window portions 51 deviates from the average opening area of ​​each window portion 51 by no more than ±2.5%. That is, within the second region 502, the opening area of ​​each window portion 51 in at least one row of window portions 51 is within the range of 97.5% to 102.5% of the average opening area of ​​each window portion 51.

[0095] To facilitate windowing of the passivation layer 50 within the second region 502, the windowing areas of at least one row of windowed portions 51 within the second region 502 can be set to the same area. However, due to errors in the fabrication process, it is difficult to guarantee that they are completely identical. Therefore, in this application, the deviation between the windowing area of ​​each windowed portion 51 in at least one row of windowed portions 51 within the second region 502 and the average windowing area of ​​each windowed portion 51 does not exceed ±2.5%. Since a certain fluctuation range is allowed, the process accuracy requirement is reduced, the cost of the windowing process is lower, and the difference in the windowing area of ​​at least one row of windowed portions 51 within the second region 502 is sufficiently small, so the windowing areas can be considered to be basically the same. In this case, it is convenient to window the second region 502 of the passivation layer 50 during fabrication, and the windowing areas of the same row of windowed portions 51 can be basically the same, thereby making the resonant frequency and ultrasonic amplitude uniform at at least one row of sub-electrodes 21 corresponding to the second region 502, so as to improve the local quality of the subsequently obtained ultrasonic image and improve the performance of the ultrasonic transducer.

[0096] Optionally, within the second region 502, the deviation between the opening area of ​​each window portion 51 in each row of window portions 51 and the average opening area of ​​each window portion 51 does not exceed ±2.5%. With this structure, the opening area of ​​each row of window portions 51 can be substantially the same, and because a certain fluctuation range is allowed, the requirements for process precision are reduced, the cost of the windowing process is lower, and the second region 502 of the passivation layer 50 can be easily windowed during preparation.

[0097] Optionally, within the second region 502, the deviation between the opening area of ​​each window portion 51 and the average opening area of ​​each window portion 51 does not exceed ±2.5%. Thus, with this structure, the opening areas of each window portion 51 can be substantially the same, and because a certain range of fluctuation is allowed, the requirements for process precision are reduced, the cost of the windowing process is lower, and the second region 502 of the passivation layer 50 can be easily windowed during fabrication.

[0098] In some optional embodiments, within the second region 502, there exists at least one set of two adjacent rows of window portions 51, satisfying the following: the deviation of both the first average area and the second average area from the target average area exceeds ±2.5%. The first average area is the average opening area of ​​the row of window portions 51 closest to the first region 501; the second average area is the average opening area of ​​the row of window portions 51 furthest from the first region 501; and the target average area is the average of the first average area and the second average area. That is, within the second region 502, there exists at least one set of two adjacent rows of window portions 51, and both the first average area and the second average area are within the range of 97.5% to 102.5% of the target average area.

[0099] Since the thickness in the thicker region of the top electrode 40 is not necessarily uniform, there may be variations in thickness (which can be considered in conjunction with...). Figure 2 , Figure 5 As shown in the figure, this may be due to the fabrication process of the top electrode 40 (such as printing process) or other factors. In this application, there is at least one set of two adjacent rows of window portions 51 in the second region 502, which satisfies that the deviations of the first average area and the second average area from the target average area both exceed ±2.5%. It can be considered that the average window area of ​​the two adjacent rows of window portions 51 is significantly different. Therefore, through the two adjacent rows of window portions 51, the passivation layer 50 can adapt to the need for thinning of the piezoelectric layer 30 when there is a thickness change in the thicker area of ​​the top electrode 40, so as to achieve targeted thinning of the piezoelectric layer 30. Thus, it can better ensure the uniformity of the resonant frequency and the uniformity of the ultrasonic amplitude at the two adjacent rows of sub-electrodes 21 corresponding to the second region 502, so as to improve the local quality of the subsequently obtained ultrasonic image and improve the performance of the ultrasonic transducer.

[0100] For example, suppose that in a pair of adjacent rows of window openings 51 in the second region 502, the first average area of ​​the row of window openings 51 closer to the first region 501 is 95 units, and the second average area of ​​the row of window openings 51 farther from the first region 501 is 105 units. Then the average of the first average area and the second average area (i.e. the target average area) is 100. The range of deviation from the target average area by ±2.5% is 97.5 to 102.5 units. Therefore, both the first average area (95 units) and the second average area (105 units) are outside this range.

[0101] For example, such as Figure 2 or Figure 5The ultrasonic transducers 100 shown all illustrate examples where the opening areas of adjacent rows of opening portions 51 within the second region 502 are significantly different. It can be seen that for different ultrasonic transducers 100, the opening areas of each row of opening portions 51 within the second region 502 can be selected differently as needed (e.g., ...). Figure 2 and Figure 5 As shown, the opening areas of the opening portions 51 in the second region 502 of the two ultrasonic transducers 100 are not exactly the same.

[0102] In some optional embodiments, in the second region 502, in each pair of adjacent rows of window portions 51, the following conditions are met: the deviation of the first average area and the second average area from the target average area both exceed ±2.5%.

[0103] As a result, the average opening area of ​​each pair of adjacent rows of windowed portions 51 in the second region 502 is significantly different. Thus, through each pair of adjacent rows of windowed portions 51, the passivation layer 50 can adapt to the need for thinning of the piezoelectric layer 30 when there are more thickness variations in the thicker area of ​​the top electrode 40, so as to achieve targeted thinning of the piezoelectric layer 30. Therefore, it can better ensure the uniformity of the resonant frequency and the uniformity of the ultrasonic amplitude at the adjacent two rows of sub-electrodes 21 in the second region 502, so as to improve the local quality of the subsequently obtained ultrasonic image and improve the performance of the ultrasonic transducer.

[0104] In some alternative embodiments, within the second region 502, the average opening area of ​​each row of window portions 51 is not equal.

[0105] Therefore, by constructing the average window area of ​​each row of windowed portions 51 in the second region 502 to be unequal, this application can adapt to the need for thinning of the piezoelectric layer 30 when the thickness of the thicker region of the top electrode 40 varies, so as to achieve targeted thinning of the piezoelectric layer 30. This can better ensure the uniformity of the resonant frequency and the uniformity of the ultrasonic amplitude at the two adjacent rows of sub-electrodes 21 corresponding to the second region 502, so as to improve the local quality of the subsequently obtained ultrasonic image and improve the performance of the ultrasonic transducer.

[0106] For example, in some examples, each row of window portions 51 in the first region 501 uses a first window area (that is, the average window area of ​​each window portion 51 in that row deviates from the first window area by no more than ±2.5%, and so on), while in the second region 502, some rows of window portions 51 may use a second window area, and other rows of window portions 51 may use a third window area (for example, see reference). Figure 4As shown, assuming Q=5 rows of window openings 51 in the second region 502, following the order from closest to furthest from the first region 501, the first and second rows of window openings 51 use the second window area, and the third, fourth, and fifth rows of window openings 51 use the third window area. Of course, this is not limited to this; more window areas can be used for these rows of window openings 51, such as the fourth window area, the fifth window area, and so on.

[0107] In some extreme examples, different window areas can be used for each row of window openings 51 in the second region 502. For example, refer to... Figure 4 As shown, assuming that Q=5 rows of window portions 51 in the second region 502, arranged in order from closest to furthest from the first region 501, the first row of window portions 51 uses a window area of ​​1, the second row of window portions 51 uses a window area of ​​2, the third row of window portions 51 uses a window area of ​​3, the fourth row of window portions 51 uses a window area of ​​4, and the fifth row of window portions 51 uses a window area of ​​5. This is merely an example and not a limitation on the embodiments of this application.

[0108] In some optional embodiments, the top electrode 40 includes a plurality of target portion top electrodes, wherein the vertical projection of the plurality of target portion top electrodes toward the substrate 10 corresponds to the vertical projection of the plurality of sub-electrodes 21 toward the substrate 10; wherein the maximum thickness of each target portion top electrode corresponding to the P row sub-electrodes 21 is less than the maximum thickness of the target portion top electrode corresponding to at least one sub-electrode 21 in the Q row sub-electrodes 21.

[0109] Based on this, since the maximum thickness of the top electrode of each target portion corresponding to the P row sub-electrode 21 is less than the maximum thickness of the top electrode of the target portion corresponding to at least one sub-electrode 21 in the Q row sub-electrode 21, and the opening area of ​​each opening portion 51 in the first region 501 is greater than the opening area of ​​each opening portion 51 in the second region 502, by adopting the above optional embodiment, it can be ensured that the first sub-electrode can be obtained from the P row sub-electrode 21 and the second sub-electrode can be obtained from the Q row sub-electrode 21. Therefore, the ultrasonic transducer 100 can better reduce the adverse effects of excessive local thickness of the top electrode 40 caused by the fabrication process of the top electrode 40. It can better reduce the thickness of more of the piezoelectric layer 30 in the thicker area of ​​the top electrode 40 through the passivation layer 50. By further thinning the piezoelectric layer, the local resonant frequency of the thicker area of ​​the top electrode 40 in the ultrasonic transducer 100 can be improved to a certain extent. This improves the local resonant frequency caused by the thicker top electrode 40, achieving the effect of local resonant frequency compensation. As a result, the uniformity of the local resonant frequency at the first sub-electrode in the P row sub-electrode corresponding to the first region 501 and the second sub-electrode in the Q row sub-electrode corresponding to the second region 502 can be improved. This effectively improves the uniformity of the ultrasonic amplitude at the first and second sub-electrodes and the local uniformity of the detection data at the two locations. This is beneficial to improving the local quality of the subsequently obtained ultrasonic image, thereby significantly improving the performance of the ultrasonic transducer 100.

[0110] In some optional embodiments, the maximum thickness of the top electrode of each target portion corresponding to the P-row sub-electrode 21 is less than the maximum thickness of the top electrode of the target portion corresponding to each sub-electrode 21 in the Q-row sub-electrode 21. Based on this, it can be ensured that the first sub-electrode can be obtained from the P-row sub-electrode 21 and the second sub-electrode can be obtained from the Q-row sub-electrode 21.

[0111] In some optional embodiments, in the Q-row sub-electrodes 21, the maximum thickness of the target portion top electrode corresponding to at least two sub-electrodes 21 is not equal, and the opening area of ​​the opening portion 51 corresponding to the at least two sub-electrodes 21 is not equal. Optionally, the greater the maximum thickness of the target portion top electrode corresponding to the sub-electrode 21, the smaller the opening area of ​​the opening portion 51 corresponding to the sub-electrode 21.

[0112] Based on this, in this application, different window areas of the window portion 51 can be used for different thicknesses of the target portion sub-electrodes corresponding to at least two sub-electrodes 21 in the Q row sub-electrodes 21. The larger the maximum thickness of the top electrode of the target portion corresponding to the sub-electrode 21, the smaller the window area of ​​the window portion 51 corresponding to the sub-electrode 21. This can achieve "gradual windowing" to meet the requirements of thinning the piezoelectric layer 30 of the at least two sub-electrodes 21 respectively, and maximize the effect of local resonant frequency compensation at the at least two sub-electrodes 21 in the Q row sub-electrodes 21. This can make the uniformity of the local resonant frequency at the at least two sub-electrodes 21 in the Q row sub-electrodes corresponding to the second region 502 better, effectively improve the uniformity of the ultrasonic amplitude at the at least two sub-electrodes 21, and improve the local uniformity of the two detection data. This is beneficial to improving the local quality of the subsequently obtained ultrasonic image, thereby improving the performance of the ultrasonic transducer 100.

[0113] For ease of understanding, the "gradual windowing" will be further explained here. In order to further enhance the compensation effect of local resonant frequency, some optional embodiments of this application may adopt a "gradual windowing" method for the passivation layer 50. The idea is as follows: Let Smax be the maximum opening area of ​​a certain window portion 51 in the passivation layer 50. If there is no window, the opening area is 0 (that is, the corresponding sub-electrode 21 can be completely covered; this is the theoretical case, but in practice, the window does not adopt a complete coverage strategy). Smax can be the opening area when the sub-electrode 21 is completely exposed, or in practice, this method can be omitted. Assuming that each window portion 51 in the first region 501 (corresponding to the region with uniform thickness of the top electrode 40) uses the same opening area, for example, denoted as the first opening area, then the first opening area can be taken as Smax to adapt to the region with uniform thickness of the top electrode 40. Using the maximum Smax and the minimum 0, the opening area percentage of a certain window portion 51 can be defined as duty = S / (Smax-0), where S is the opening area of ​​that window portion 51. Obviously, if the window is at its maximum, duty = 100%; if there is no window, duty = 0%. Figure 2 , Figure 3 or Figure 5 As shown, the thickness of the portion of the piezoelectric layer 30 that contacts the sub-electrode 21 (which can be direct contact or contact through an adhesive layer) can be denoted as d0, and the thickness of the portion of the piezoelectric layer 30 that contacts the passivation layer 50 can be denoted as d1. Then, for a sub-electrode 21 corresponding to a certain window portion 51, its corresponding equivalent piezoelectric layer thickness can be denoted as: d1+(d0-d1)*duty. Therefore, by changing the window area S of the window portion 51, the window area ratio duty can be adjusted, and the equivalent piezoelectric layer thickness corresponding to the sub-electrode 21 can be flexibly adjusted between d1 and d0.

[0114] Because the maximum thickness of the top electrode 40 at different positions within the second region 502 may vary, i.e., the thickness may differ, the required thickness of the piezoelectric layer 30 for each sub-electrode 21 in the Q row may also differ. Therefore, as can be seen from the above explanation, by setting the opening area S of the opening portion 51 corresponding to different sub-electrodes 21 as needed (for example, setting the opening area S of the opening portion 51 according to the different maximum thicknesses of the top electrode corresponding to different sub-electrodes 21), and adjusting the different opening area ratios, the corresponding piezoelectric layer 30 can be thinned precisely and accurately for the sub-electrode 21, and the local resonant frequency compensation of the sub-electrode 21 can be precisely achieved, thereby enhancing the effect of local resonant frequency compensation of the sub-electrode 21.

[0115] It is understood that, by adopting the above optional method, the window areas of the window portions 51 corresponding to at least two sub-electrodes 21 in the second region 502 can be different (for example, the larger the maximum thickness of the top electrode of the target portion corresponding to the sub-electrode 21, the smaller the window area of ​​the window portion 51 corresponding to the sub-electrode 21), which can be called "gradual windowing". Through the above optional method, the uniformity of the local resonant frequency at at least two sub-electrodes 21 in the Q row of sub-electrodes corresponding to the second region 502 can be better, effectively improving the uniformity of the ultrasonic amplitude at the at least two sub-electrodes 21 and improving the local uniformity of the two detection data, which is beneficial to improving the local quality of the subsequently obtained ultrasonic image, thereby improving the performance of the ultrasonic transducer 100.

[0116] To achieve different window area ratios, the window pattern of the window section 51 can be flexibly set, such as a single window or a combination of multiple windows (as explained earlier, it will not be repeated here). Choose as needed. Example: Figure 6 A single window in subgraph a or subgraph b, or a combination of multiple windows in subgraphs c, d, and e. Furthermore... Figure 6 Subfigures a and f also show examples with duty levels of 100% and 0%. It should be understood that, since duty is 100% in subfigure a, the window 51 completely exposes the sub-electrode 21; conversely, since duty is 0% in subfigure f, the sub-electrode is fully covered by the passivation layer 50, with no window 51. Furthermore, the "21" marked in subfigure f indicates the location of the sub-electrode fully covered by the passivation layer 50. It should be understood that... Figure 6 The examples shown are not intended to limit the embodiments of this application.

[0117] It is understandable that some of the optional embodiments mentioned above also embody the concept of "gradual window opening".

[0118] In some alternative embodiments, for the second sub-electrode, the sum of the thickness of the piezoelectric layer 30 embedded in the window portion 51 and the thickness of the piezoelectric layer 30 directly above the window portion 51 is greater than the thickness of the piezoelectric layer 30 directly above the covered portion, wherein the covered portion is the portion of the passivation layer 50 covering the second sub-electrode.

[0119] For example, refer to Figure 3 As shown, taking the second sub-electrode 212 as an example, the thickness of the piezoelectric layer 30 embedded in the window portion 51 (i.e., Figure 3 (d2) and the thickness of the piezoelectric layer 30 directly above the window 51 ( Figure 3 The sum of the values ​​of d0 (equal to d1 in the example) is d0, and the thickness of the piezoelectric layer 30 directly above the covered portion is d1. It can be seen that because the passivation layer 50 thins the piezoelectric layer 30, d0 is greater than d1. This can also be understood in conjunction with the aforementioned content regarding the window area ratio (duty). Furthermore, it can be understood that the piezoelectric layer 30 embedded in the window portion 51, the piezoelectric layer 30 directly above the window portion 51, and the covered portion, together, constitute the second part of the piezoelectric layer.

[0120] It should be understood that, through the aforementioned optional structure, this application can effectively achieve the thinning of the piezoelectric layer 30 on the second sub-electrode. By thinning the piezoelectric layer, the local resonant frequency at the location where the local top electrode 40 is thicker than the second sub-electrode can be adjusted. This improves the local resonant frequency at the second sub-electrode, which is lower due to the thickness of the second part of the top electrode 40, thus achieving the effect of local resonant frequency compensation. This effectively improves the uniformity of ultrasonic amplitude at both the second and first sub-electrodes and enhances the local uniformity of the detection data at both locations. This is beneficial for improving the local quality of the subsequently obtained ultrasonic image, thereby significantly improving the performance of the ultrasonic transducer 100.

[0121] It is understood that the above content is only some optional implementations of the ultrasonic transducer 100 in the embodiments of this application, and is not intended to limit the embodiments of this application.

[0122] According to the second aspect of the embodiments of this application, an ultrasonic transducer 100 is provided, which can still be referred to Figure 2 , Figure 3 and Figure 5As shown, the ultrasonic transducer 100 may include: a substrate 10, a bottom electrode 20, a piezoelectric layer 30, and a top electrode 40; the bottom electrode 20 includes a plurality of sub-electrodes 21 located on the upper surface of the substrate 10; the piezoelectric layer 30 is located above the bottom electrode 20; wherein, the plurality of sub-electrodes 21 include at least a first sub-electrode and a second sub-electrode, and the piezoelectric layer 30 includes a first portion piezoelectric layer and a second portion piezoelectric layer, wherein the vertical projection of the first sub-electrode toward the substrate 10 coincides with the vertical projection of the first portion piezoelectric layer toward the substrate 10, and the vertical projection of the second sub-electrode toward the substrate 10 coincides with the vertical projection of the second portion piezoelectric layer toward the substrate 10; wherein, the volume of the first portion piezoelectric layer is larger than the volume of the second portion piezoelectric layer, and the second sub-electrode is closer to the edge of the target side of the bottom electrode 20 than the first sub-electrode.

[0123] It should be understood that, in the aforementioned optional ultrasonic transducer 100, since the volume of its first piezoelectric layer is larger than that of its second piezoelectric layer, a greater portion of the first piezoelectric layer above the first sub-electrode is thinned compared to the second piezoelectric layer above the second sub-electrode. This allows for more targeted thinning of the piezoelectric layer, which can compensate to some extent for the performance deviation of the local resonant frequency between the second and first sub-electrodes caused by the edge effect of the ultrasonic transducer electrode structure. This improves the potentially low local resonant frequency, thereby enhancing the uniformity of the local resonant frequencies between the first and second sub-electrodes. This effectively improves the uniformity of the ultrasonic amplitude at both sub-electrodes and enhances the local uniformity of the detection data at both locations. This is beneficial for improving the local quality of the subsequently obtained ultrasonic image, thus significantly improving the performance of the ultrasonic transducer 100.

[0124] In some alternative embodiments, the edge of the target side of the bottom electrode 20 may be the edge of the side closer to the thicker region of the top electrode 40.

[0125] In some alternative embodiments, reference may be made to Figure 2 , Figure 3 and Figure 5As shown, the ultrasonic transducer 100 may include: a substrate 10, a bottom electrode 20, a piezoelectric layer 30, and a top electrode 40; the bottom electrode 20 includes a plurality of sub-electrodes 21 located on the upper surface of the substrate 10; the piezoelectric layer 30 is located above the bottom electrode 20; the top electrode 40 is at least partially located above the piezoelectric layer 30; the plurality of sub-electrodes 21 include at least a first sub-electrode and a second sub-electrode, the piezoelectric layer 30 includes a first portion piezoelectric layer and a second portion piezoelectric layer, and the top electrode 40 includes a first portion top electrode and a second portion top electrode, wherein: the vertical projections of the first sub-electrode toward the substrate 10, the vertical projections of the first portion piezoelectric layer toward the substrate 10, and the vertical projections of the first portion top electrode toward the substrate 10 coincide with each other; the vertical projections of the second sub-electrode toward the substrate 10, the vertical projections of the second portion piezoelectric layer toward the substrate 10, and the vertical projections of the second portion top electrode toward the substrate 10 coincide with each other; the maximum thickness of the first portion top electrode is less than the maximum thickness of the second portion top electrode, and the volume of the first portion piezoelectric layer is greater than the volume of the second portion piezoelectric layer.

[0126] Optionally, the second sub-electrode is closer to the edge of the target side of the bottom electrode 20 than the first sub-electrode.

[0127] It should be noted that, regarding the ultrasonic transducer 100 in the second aspect, a structure can be adopted as in the first aspect, which uses a passivation layer 50 to achieve thinning, so that the volume of the first piezoelectric layer is larger than the volume of the second piezoelectric layer. However, it is not limited to using a passivation layer 50 to achieve this. As long as the purpose can be achieved, it is acceptable and no restrictions are imposed here.

[0128] It should be understood that, in the aforementioned optional ultrasonic transducer 100, since the volume of its first piezoelectric layer is larger than that of its second piezoelectric layer, a greater portion of the first piezoelectric layer above the first sub-electrode is thinned compared to the second piezoelectric layer above the second sub-electrode. This allows for a greater reduction in the piezoelectric layer thickness, thereby increasing the local resonant frequency at the second sub-electrode in the ultrasonic transducer 100 to some extent. This improves the local resonant frequency compensation effect caused by the thicker second top electrode 42, resulting in better uniformity of the local resonant frequencies at the first and second sub-electrodes. This effectively improves the uniformity of the ultrasonic amplitude at both sub-electrodes and enhances the local uniformity of the detection data at both locations. This, in turn, improves the local quality of the subsequently obtained ultrasonic image, thus significantly improving the performance of the ultrasonic transducer 100.

[0129] It should be understood that the ultrasonic transducer 100 in the second aspect can be referred to the relevant structure of the ultrasonic transducer 100 in the first aspect above, which has been described in detail above. Therefore, it can also be understood by referring to the embodiments above, and will not be repeated here.

[0130] According to a third aspect of the embodiments of this application, referring to Figure 7 As shown, an ultrasonic fingerprint module 200 is provided, including an ultrasonic transducer 100 as provided in the first or second aspect.

[0131] Since the ultrasonic fingerprint module 200 of the third aspect includes the ultrasonic transducer 100 of the first or second aspect, it has better performance and can better realize the ultrasonic fingerprint function.

[0132] According to the fourth aspect of the embodiments of this application, referring to Figure 8A , Figure 8B As shown, an electronic device 300 is provided, including: the ultrasonic transducer 100 provided in the first or second aspect above, or the ultrasonic fingerprint module 200 provided in the third aspect above.

[0133] Optionally, the electronic device 300 can be any electronic device, including but not limited to any terminal or non-terminal device, as long as there is a need for ultrasonic detection, such as, but not limited to, mobile phones and computers. It should be understood that this application does not limit the way the ultrasonic transducer 100 or the ultrasonic fingerprint module 200 is configured in the electronic device 300.

[0134] As an example, taking an electronic device 300 as a mobile phone and including an ultrasonic transducer 100, the ultrasonic transducer 100 can be bonded to the bottom of the screen, the inside of the side frame, the inside of the back panel, etc. of the electronic device 300 through an adhesive layer for under-screen ultrasonic biometric detection, side ultrasonic biometric detection, back ultrasonic biometric detection, etc.

[0135] As another example, taking an electronic device 300 as a mobile phone and including an ultrasonic fingerprint module 200, the ultrasonic fingerprint module 200 can be bonded to the inside of the mobile phone screen, the side bezel, the back panel, etc. of the electronic device 300 through an adhesive layer to achieve under-screen ultrasonic fingerprint detection, side ultrasonic fingerprint detection, and rear ultrasonic fingerprint detection.

[0136] This application also provides a method for manufacturing an ultrasonic transducer. (Refer to...) Figure 9 The flowchart shown illustrates the fabrication method of the ultrasonic transducer, which includes the following steps S102, S104, S106, and S108, specifically: S102: Obtain a substrate with a bottom electrode formed on its upper surface, wherein the bottom electrode includes a plurality of sub-electrodes; S104: A passivation layer is formed above the substrate, partially covering the bottom electrode, and the passivation layer is provided with a plurality of openings corresponding to the positions of a plurality of sub-electrodes respectively. S106: Above the passivation layer, a piezoelectric layer is formed that is partially embedded in multiple openings; S108: Form a top electrode that is at least partially located above the piezoelectric layer to fabricate an ultrasonic transducer.

[0137] The formed sub-electrodes include at least a first sub-electrode and a second sub-electrode, and the formed top electrode includes a first part top electrode and a second part top electrode. The vertical projection of the first sub-electrode toward the substrate coincides with the vertical projection of the first part top electrode toward the substrate, and the vertical projection of the second sub-electrode toward the substrate coincides with the vertical projection of the second part top electrode toward the substrate. The maximum thickness of the first part top electrode is less than the maximum thickness of the second part top electrode. The first opening area of ​​the opening portion corresponding to the first sub-electrode is greater than the second opening area of ​​the opening portion corresponding to the second sub-electrode.

[0138] It should be understood that the optional fabrication methods in S102 to S108 described above for fabricating the ultrasonic transducer 100, by setting a passivation layer 50 and ensuring that the first opening area of ​​the window portion 51 of the passivation layer 50 corresponding to the first sub-electrode is larger than the second opening area of ​​the window portion 51 of the passivation layer 50 corresponding to the second sub-electrode, a larger portion of the piezoelectric layer 30 above the second sub-electrode can be thinned through the passivation layer 50 compared to the piezoelectric layer 30 above the first sub-electrode. This allows for greater thinning of the piezoelectric layer 30, thereby improving the quality of the fabricated ultrasonic transducer to a certain extent. The local resonant frequency at the second sub-electrode in 100 is increased to compensate for the low local resonant frequency at the second sub-electrode caused by the thicker top electrode in the second part. This results in better uniformity of the local resonant frequencies at the first and second sub-electrodes, effectively improving the uniformity of the ultrasonic amplitude at both sub-electrodes and enhancing the local uniformity of the detection data at both locations. This is beneficial for improving the local quality of the prepared ultrasonic image, thereby significantly improving the performance of the prepared ultrasonic transducer 100.

[0139] Optionally, the second sub-electrode is closer to the edge of the target side of the bottom electrode 20 than the first sub-electrode.

[0140] In some alternative embodiments, the bottom electrode 20 can be fabricated using any feasible process, including but not limited to deposition, etching, electroplating, etc.

[0141] In some alternative embodiments, when preparing the passivation layer 50, a whole layer of passivation layer material can be covered on the substrate 10, which includes the bottom electrode 20, and then the portion of the whole layer of passivation layer material that needs to expose multiple sub-electrodes 21 can be etched to expose multiple sub-electrodes 21. The openings obtained by etching on the passivation layer 50 are used to form multiple opening portions 51.

[0142] In some optional embodiments, the piezoelectric layer 30 can be formed on the substrate 10 in any suitable manner, without particular limitation. For example, it can be achieved by means including but not limited to coating, screen printing, dry film lamination, etc., or by physical or chemical vapor deposition methods such as sputtering and evaporation.

[0143] In some alternative embodiments, forming a top electrode that is at least partially located above the piezoelectric layer includes forming the top electrode by a printing process. For example, the printing process may include, but is not limited to, screen printing, stencil printing, etc. Alternatively, the top electrode 40 may also be fabricated using any other feasible process, including but not limited to post-sputtering etching, deposition, electroplating, etc.

[0144] In some optional embodiments, the method further includes forming a protective layer covering at least a portion of the top electrode. Optionally, the protective layer may completely cover the top electrode 40 for better protection.

[0145] In some alternative embodiments, the piezoelectric layer is partially embedded in a plurality of windows and in contact with a plurality of sub-electrodes; or, the piezoelectric layer is partially embedded in a plurality of windows and the piezoelectric layer is in contact with a plurality of sub-electrodes through an adhesive layer.

[0146] In some optional embodiments, the passivation layer formed includes a window portion corresponding to the sub-electrode position, comprising all windows whose vertical projection toward the sub-electrode is located on the sub-electrode.

[0147] In some optional embodiments, the formed plurality of sub-electrodes are arranged in N rows along a first direction on the upper surface of the substrate, where N≥2 and N is an integer; the formed passivation layer includes a first region and a second region, the first region includes P rows of window portions corresponding to P rows of sub-electrodes, and the second region includes Q rows of window portions corresponding to Q rows of sub-electrodes, where the Q rows of sub-electrodes and the P rows of sub-electrodes are different rows of sub-electrodes in the N rows of sub-electrodes, where P≥1, Q≥1, and P and Q are both integers; wherein, the window area of ​​each window portion in the first region is greater than the window area of ​​each window portion in the second region; the P rows of sub-electrodes include a first sub-electrode, and the Q rows of sub-electrodes include a second sub-electrode.

[0148] In some optional embodiments, P+Q=N, P rows of sub-electrodes are arranged adjacently along the first direction, Q rows of sub-electrodes are arranged adjacently along the first direction, and the first region and the second region are arranged adjacently along the first direction, or the first region and the second region are arranged adjacently in the opposite direction of the first direction.

[0149] In some alternative embodiments, the ultrasonic transducer further includes a pad area for electrical connection between the ultrasonic transducer and an external circuit, wherein, along a first direction, a second region is located between the first region and the pad area, or the first region is located between the second region and the pad area.

[0150] In some alternative embodiments, within the second region, the window area of ​​each window in at least one row of window openings deviates from the average window area of ​​each window opening by no more than ±2.5%.

[0151] In some optional embodiments, within the second region, there exists at least one set of two adjacent rows of window openings that satisfy the following: the deviation of both the first average area and the second average area from the target average area exceeds ±2.5%, wherein the first average area is the average window opening area of ​​the row of window openings closer to the first region among the two adjacent rows of window openings; the second average area is the average window opening area of ​​the row of window openings farther from the first region among the two adjacent rows of window openings; and the target average area is the average of the first average area and the second average area.

[0152] In some optional embodiments, in the second region, in each pair of adjacent rows of window openings, the following conditions are met: the deviation of the first average area and the second average area from the target average area both exceed ±2.5%.

[0153] In some alternative embodiments, the average window area of ​​each row of windows in the second region is not equal.

[0154] In some alternative embodiments, within the first region, the window area of ​​each window in at least one row of window openings deviates from the average window area of ​​each window opening by no more than ±2.5%.

[0155] In some optional embodiments, the formed top electrode includes a plurality of target partial top electrodes, wherein the vertical projection of the plurality of target partial top electrodes toward the substrate coincides with the vertical projection of the plurality of sub-electrodes toward the substrate; wherein the maximum thickness of each target partial top electrode corresponding to the P row sub-electrodes is less than the maximum thickness of the target partial top electrode corresponding to at least one sub-electrode in the Q row sub-electrodes.

[0156] In some optional embodiments, in the Q-row sub-electrodes, the maximum thickness of the target portion top electrode corresponding to at least two sub-electrodes is not equal, and the opening area of ​​the opening portion corresponding to the at least two sub-electrodes is not equal, wherein the greater the maximum thickness of the target portion top electrode corresponding to the sub-electrode, the smaller the opening area of ​​the opening portion corresponding to the sub-electrode.

[0157] In some alternative embodiments, for the second sub-electrode, the sum of the thickness of the piezoelectric layer embedded in the window and the thickness of the piezoelectric layer directly above the window is greater than the thickness of the piezoelectric layer directly above the covered portion, wherein the covered portion is the portion of the passivation layer covering the second sub-electrode.

[0158] In some alternative embodiments, the formed plurality of window openings includes at least one of a first type of window opening and a second type of window opening, wherein: the first type of window opening includes a single window; and the second type of window opening includes a combination of a plurality of windows.

[0159] In some optional embodiments, the plurality of window portions formed includes at least one target window portion, wherein the first center of the target window portion facing the vertical projection of the sub-electrode corresponding to the target window portion coincides with the second center of the sub-electrode.

[0160] It should be understood that the preparation method of the ultrasonic transducer described above has been explained in the embodiment of the ultrasonic transducer 100 in the first aspect above, and can be understood by referring to the embodiment above, so it will not be repeated here.

[0161] It is understood that the above descriptions of various aspects of the embodiments of this application are merely optional exemplary descriptions of the technical solutions of the embodiments of this application, and are not intended to limit the embodiments of this application in any way.

[0162] The optional embodiments of the present application have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present application are not limited thereto. It should be noted that, for the convenience of explaining the embodiments of the present application, the various drawings of the embodiments of the present application are not necessarily drawn to scale, and are only used to facilitate the explanation of the technical solution, and are not intended to limit the embodiments of the present application in any way. Within the scope of the technical concept of the embodiments of the present application, various simple modifications can be made to the technical solutions of the embodiments of the present application. The various technical features included in the different embodiments of the present application can be separated and / or combined in any suitable manner. In order to avoid unnecessary repetition, the embodiments of the present application will not describe the various possible combinations separately. However, these simple modifications and combinations should also be regarded as the content disclosed in the embodiments of the present application, and all fall within the protection scope of the embodiments of the present application.

[0163] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional 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 intended to limit the order of functions performed by these devices, modules, or units or their interdependencies. It should be noted that the modifications "a" and "a plurality" mentioned in this application are illustrative rather than restrictive, and those skilled in the art should understand that, unless explicitly indicated in the context, they should be understood as "one or more".

[0164] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions 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 this application.

Claims

1. An ultrasonic transducer, comprising: Substrate; The bottom electrode includes a plurality of sub-electrodes located on the upper surface of the substrate; A passivation layer is located above the substrate and partially covers the bottom electrode. The passivation layer is provided with a plurality of openings corresponding to the positions of a plurality of sub-electrodes. A piezoelectric layer is located above the passivation layer and is partially embedded in multiple openings; Among them, the plurality of sub-electrodes includes at least a first sub-electrode and a second sub-electrode. The first opening area of ​​the opening portion corresponding to the first sub-electrode is greater than the second opening area of ​​the opening portion corresponding to the second sub-electrode. The second sub-electrode is closer to the edge of the target side of the bottom electrode than the first sub-electrode.

2. The ultrasonic transducer according to claim 1, wherein, The passivation layer includes a window portion corresponding to the position of the sub-electrode, comprising all windows whose vertical projection toward the sub-electrode is located on the sub-electrode.

3. The ultrasonic transducer according to claim 1, wherein, The piezoelectric layer is partially embedded in multiple windowed portions and in contact with the multiple sub-electrodes; or, the piezoelectric layer is partially embedded in multiple windowed portions and the piezoelectric layer is in contact with the multiple sub-electrodes through an adhesive layer.

4. The ultrasonic transducer according to claim 1, wherein, The ultrasonic transducer further includes a top electrode, which is at least partially located above the piezoelectric layer; The top electrode includes a first part top electrode and a second part top electrode. The vertical projection of the first sub-electrode toward the substrate coincides with the vertical projection of the first part top electrode toward the substrate, and the vertical projection of the second sub-electrode toward the substrate coincides with the vertical projection of the second part top electrode toward the substrate. The maximum thickness of the first part top electrode is less than the maximum thickness of the second part top electrode.

5. The ultrasonic transducer according to claim 4, wherein, The plurality of sub-electrodes are arranged in N rows along a first direction on the upper surface of the substrate, where N ≥ 2 and N is an integer; The passivation layer includes a first region and a second region. The first region includes a P-row window corresponding to the P-row sub-electrode, and the second region includes a Q-row window corresponding to the Q-row sub-electrode. The Q-row sub-electrode and the P-row sub-electrode are different rows of sub-electrodes in the N-row sub-electrodes, where P≥1, Q≥1, and P and Q are both integers. In this area, the window area of ​​each window in the first region is greater than the window area of ​​each window in the second region. The P-row sub-electrode includes the first sub-electrode, and the Q-row sub-electrode includes the second sub-electrode.

6. The ultrasonic transducer according to claim 5, wherein, P+Q=N, where the P-row sub-electrodes are arranged adjacently along the first direction, the Q-row sub-electrodes are arranged adjacently along the first direction, and the first region and the second region are arranged adjacently along the first direction, or the first region and the second region are arranged adjacently in the opposite direction of the first direction.

7. The ultrasonic transducer according to claim 6, wherein, The ultrasonic transducer also includes a pad area for electrical connection between the ultrasonic transducer and an external circuit. Along the first direction, the second region is located between the first region and the pad area, or the first region is located between the second region and the pad area.

8. The ultrasonic transducer according to any one of claims 5-7, wherein, Within the second region, the deviation of the opening area of ​​each opening in at least one row of openings from the average opening area of ​​each opening shall not exceed ±2.5%.

9. The ultrasonic transducer according to claim 8, wherein, Within the second region, there exists at least one pair of adjacent rows of window openings that satisfy the following conditions: the deviations of both the first average area and the second average area from the target average area exceed ±2.5%. The first average area is the average window area of ​​the row of windows closest to the first region among the two adjacent rows of windows. The second average area is the average window area of ​​the row of windows that is furthest from the first area in the two adjacent rows of windows; The target area average is the average of the first area average and the second area average.

10. The ultrasonic transducer according to claim 9, wherein, Within the second region, in each pair of adjacent rows of window openings, the following conditions are met: the deviation of the first average area and the second average area from the target average area both exceed ±2.5%.

11. The ultrasonic transducer according to claim 8, wherein, Within the second region, the average window area of ​​each row of windows is not equal.

12. The ultrasonic transducer according to any one of claims 5-7, wherein, Within the first region, the deviation of the opening area of ​​each opening in at least one row of openings from the average opening area of ​​each opening shall not exceed ±2.5%.

13. The ultrasonic transducer according to any one of claims 5-7, wherein, The top electrode includes multiple target portion top electrodes, wherein the vertical projections of the multiple target portion top electrodes toward the substrate respectively coincide with the vertical projections of the multiple sub-electrodes toward the substrate; The maximum thickness of the top electrode of each target portion corresponding to the P row sub-electrode is less than the maximum thickness of the top electrode of the target portion corresponding to at least one sub-electrode in the Q row sub-electrode.

14. The ultrasonic transducer according to claim 13, wherein, In the Q-row sub-electrodes, the maximum thickness of the target portion top electrode corresponding to at least two sub-electrodes is not equal, and the opening area of ​​the opening portion corresponding to the at least two sub-electrodes is not equal. Furthermore, the greater the maximum thickness of the target portion top electrode corresponding to the sub-electrode, the smaller the opening area of ​​the opening portion corresponding to the sub-electrode.

15. The ultrasonic transducer according to any one of claims 1-7, wherein, For the second sub-electrode, the sum of the thickness of the piezoelectric layer embedded in the window and the thickness of the piezoelectric layer directly above the window is greater than the thickness of the piezoelectric layer directly above the covered portion, wherein the covered portion is the part of the passivation layer covering the second sub-electrode.

16. The ultrasonic transducer according to any one of claims 1-7, wherein, The plurality of window openings includes at least one of a first type of window opening and a second type of window opening, wherein: The first type of window opening includes a single window; The second type of window opening includes a combination of multiple windows.

17. An ultrasonic transducer, comprising: Substrate; The bottom electrode includes a plurality of sub-electrodes located on the upper surface of the substrate; A piezoelectric layer is located above the bottom electrode; The plurality of sub-electrodes includes at least a first sub-electrode and a second sub-electrode, and the piezoelectric layer includes a first portion of the piezoelectric layer and a second portion of the piezoelectric layer, wherein: The vertical projection of the first sub-electrode toward the substrate coincides with the vertical projection of the first portion of the piezoelectric layer toward the substrate, and the vertical projection of the second sub-electrode toward the substrate coincides with the vertical projection of the second portion of the piezoelectric layer toward the substrate; The volume of the first piezoelectric layer is larger than that of the second piezoelectric layer, and the second sub-electrode is closer to the edge of the target side of the bottom electrode than the first sub-electrode.

18. The ultrasonic transducer according to claim 17, wherein, The ultrasonic transducer further includes a top electrode, which is at least partially located above the piezoelectric layer; The top electrode includes a first part of the top electrode and a second part of the top electrode, wherein: The vertical projections of the first sub-electrode toward the substrate, the vertical projections of the first portion of the piezoelectric layer toward the substrate, and the vertical projections of the first portion of the top electrode toward the substrate coincide with each other. The vertical projections of the second sub-electrode toward the substrate, the vertical projections of the second piezoelectric layer toward the substrate, and the vertical projections of the second top electrode toward the substrate coincide with each other; The maximum thickness of the first part of the top electrode is less than the maximum thickness of the second part of the top electrode.

19. An ultrasonic fingerprint module, comprising: The ultrasonic transducer as described in any one of claims 1-18.

20. An electronic device, comprising: The ultrasonic transducer as described in any one of claims 1-18, or the ultrasonic fingerprint module as described in claim 19.

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