Pmut array ultrasonic transducer

Abstract

The application discloses a PMUT array ultrasonic transducer, which comprises a PCB substrate and a plurality of independent PMUT array elements, wherein a plurality of array-arranged patch regions are arranged on the PCB substrate, the PMUT array elements are detachably connected to the patch regions, and the PMUT array elements correspond to the patch regions one by one. According to different ultrasonic wave transmitting and receiving requirements, different PMUT array elements can be selected to combine a PMUT array ultrasonic transducer, so that the ultrasonic wave transmitting and receiving of multiple frequencies and wide bandwidth can be realized, and the reusability and adaptability of the PMUT array ultrasonic transducer are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of detectors, and particularly relates to a PMUT array ultrasonic transducer. BACKGROUND

[0002] Ultrasonic transducers play an important role in various application fields, especially in medical imaging, object detection, and acoustic sensing. In recent years, PMUT (Piezoelectric Micromachined Ultrasonic Transducers) array ultrasonic transducers based on piezoelectric micro-machining technology have attracted widespread attention due to their small size, high sensitivity, and low energy consumption characteristics. However, despite significant progress in theory and application, existing PMUT array ultrasonic transducers still have some key problems.

[0003] The PMUT array in the prior art usually adopts an integrated design, which means that all single elements in the array are fixed. Such a design, although having certain convenience in the manufacturing process, is relatively limited in actual application. The main disadvantage of the integrated PMUT array is that the single elements are not replaceable, resulting in insufficient flexibility of the entire array when facing different detection scenarios. For example, in application scenarios requiring different frequencies or different beam characteristics, the existing integrated PMUT array cannot be adjusted to adapt to these needs, which limits its application range.

[0004] In addition, the integrated PMUT array also faces challenges when a single element is damaged. In the prior art, if any element in the array is damaged, the entire array usually needs to be replaced, which undoubtedly increases the use cost and maintenance difficulty.

[0005] Therefore, in view of the above technical problems, it is necessary to provide a new PMUT array ultrasonic transducer. SUMMARY

[0006] The purpose of the present application is to provide a PMUT array ultrasonic transducer which can replace PMUT elements to combine into ultrasonic transducers with different performance, and can adapt to different application scenarios.

[0007] To achieve the above-mentioned purpose, the technical solution provided by the present application is as follows:

[0008] A PMUT array ultrasonic transducer comprises a PCB substrate and a plurality of mutually independent PMUT elements, the PCB substrate is provided with a plurality of array-arranged patch regions, the PMUT elements are detachably joined to the patch regions, and the PMUT elements correspond one-to-one to the patch regions.

[0009] In one or more embodiments, the PMUT array elements are detachably joined to the patch area by an adhesive capable of being heated and melted.

[0010] In one or more embodiments, the PMUT array element comprises a chip layer and, sequentially stacked from bottom to top on the upper surface of the chip layer, a lower electrode, a piezoelectric layer and an upper electrode.

[0011] In one or more embodiments, the chip layer comprises, sequentially stacked from bottom to top, a substrate layer, an oxidation layer and a support layer, the substrate layer being provided with a first cavity penetrating through the substrate layer.

[0012] In one or more embodiments, the substrate layer is a silicon wafer, the oxidation layer is a silicon dioxide layer, and the support layer is a monocrystalline silicon layer.

[0013] In one or more embodiments, the patch area is provided with a second cavity penetrating through the PCB substrate at the first cavity, and the first cavity and the second cavity are coaxial.

[0014] In one or more embodiments, a groove structure is formed between any two adjacent PMUT array elements.

[0015] In one or more embodiments, the width of the groove structure is w, and the depth of the groove structure is equal to the thickness of the chip layer; wherein, c is the speed of sound, f is the resonance frequency, and a is the width of the chip layer.

[0016] In one or more embodiments, a plurality of electrode pads are provided on the PCB substrate, and the upper electrode and the lower electrode are electrically connected to the electrode pads by metal wires.

[0017] In one or more embodiments, the material of the upper electrode is gold, the material of the lower electrode is molybdenum, and the material of the piezoelectric layer is scandium-doped aluminum nitride.

[0018] Compared with the prior art, each PMUT array element in the PMUT array ultrasonic transducer provided by the present application is independent and detachable, and different PMUT array elements can be combined to form a PMUT array ultrasonic transducer according to different ultrasonic emission and reception requirements, so as to realize multi-frequency and wide-band ultrasonic emission and reception, and improve the reusability and adaptability of the PMUT array ultrasonic transducer. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on these drawings.

[0020] Figure 1 A perspective view of a PMUT array ultrasonic transducer in an embodiment of the present application.

[0021] Figure 2 A perspective view of a PMUT array ultrasonic transducer in an embodiment of the present application. Figure 1 A side view of the PMUT array ultrasonic transducer shown in FIG. 4.

[0022] Figure 3 A perspective view of a PMUT array ultrasonic transducer in an embodiment of the present application. Figure 1 A perspective view of the PCB substrate in the PMUT array ultrasonic transducer shown in FIG. 5.

[0023] Figure 4 A perspective view of the PMUT array ultrasonic transducer in an embodiment of the present application. Figure 1 A perspective view of the PMUT array element in the PMUT array ultrasonic transducer shown in FIG. 6.

[0024] Figure 5 A perspective view of the PMUT array ultrasonic transducer in an embodiment of the present application. Figure 1 A perspective view of the chip layer in the PMUT array ultrasonic transducer shown in FIG. 7.

[0025] Figure 6 A perspective view of a PMUT array ultrasonic transducer in another embodiment of the present application.

[0026] Main figure mark explanation:

[0027] 1-PCB substrate, 11-patch area, 12-second cavity, 13-electrode pad, 2-PMUT array element, 21-chip layer, 211-substrate layer, 212-oxide layer, 213-support layer, 214-first cavity, 22-lower electrode, 23-piezoelectric layer, 24-upper electrode, 3-trench structure, 4-adhesive, 5-metal wire. DETAILED DESCRIPTION

[0028] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on these drawings.

[0029] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0030] Existing integrated PMUT array ultrasonic transducer technology generally suffers from several limitations, particularly regarding the fixed and non-replaceable nature of the array elements. The limitations of this integrated design manifest in that if any element fails, the entire array needs to be replaced, leading to increased costs and reduced application flexibility. Furthermore, this design cannot adapt to diverse application scenarios, such as those requiring specific frequencies or beam characteristics.

[0031] The core idea of ​​this invention is to provide a novel PMUT array ultrasonic transducer. This idea is based on two key points: First, designing individually replaceable PMUT elements so that when an element is damaged or a special function is required, only the relevant element can be replaced instead of the entire array. Second, developing a novel PCB (printed circuit board) substrate with multiple patch areas for accommodating and securing these replaceable PMUT elements. This design not only reduces maintenance costs but also provides greater customization and application flexibility.

[0032] like Figures 1 to 3 As shown, in one embodiment of the present invention, a PMUT array ultrasonic transducer includes a PCB substrate 1 and a plurality of independent PMUT array elements 2. The PCB substrate 1 has a plurality of patch regions 11 arranged in an array; the PMUT array elements 2 are detachably attached to the patch regions 11, and the PMUT array elements 2 correspond one-to-one with the patch regions 11.

[0033] The PCB substrate 1 is the basic component of the PMUT array ultrasonic transducer. It has multiple array-arranged patch areas 11, providing a dedicated mounting position for each PMUT element 2, ensuring precise alignment and electrical connection between the elements. The PCB substrate 1 provides a stable support and electrical connection interface for the PMUT elements 2, ensuring the structural stability and electrical performance of the entire array, and providing an interface with external circuits.

[0034] PMUT element 2 is the core functional component of the PMUT array ultrasonic transducer. It is detachably attached to patch area 11 on PCB substrate 1, and corresponds one-to-one with patch area 11 to form PMUT array. PMUT element 2 can transmit and receive ultrasonic waves to realize ultrasonic imaging and detection functions.

[0035] The PMUT array elements 2 in the PMUT array ultrasonic transducer provided by the application are independent of each other, that is, each PMUT array element 2 has its own resonant frequency and bandwidth, and is not affected by other PMUT array elements 2. Therefore, different combinations of PMUT array elements 2 can be selected to form a PMUT array ultrasonic transducer according to different ultrasonic wave transmission and reception requirements, so as to realize multi-frequency and wide-band ultrasonic wave transmission and reception, and improve the reusability and adaptability of the PMUT array ultrasonic transducer.

[0036] For example, different elements in the PMUT array can be combined in the form of same frequency and same structure, same frequency and different structure (different structures of elements with the same frequency), different frequency and different structure, and different frequency and same structure, to improve the transmission or / and reception performance of the device according to actual requirements.

[0037] The PMUT array elements 2 in the PMUT array ultrasonic transducer provided by the application are detachable, that is, the PMUT array elements 2 can be removed or installed on the patch area 11 on the PCB substrate 1 as needed. In this way, if a certain PMUT array element 2 fails or is damaged, it can be replaced individually without affecting the performance of the entire array, and the entire array does not need to be replaced, thereby improving the maintainability and reconfigurability of the PMUT array ultrasonic transducer.

[0038] The PMUT array elements 2 in the PMUT array ultrasonic transducer provided by the application are replaceable, that is, different PMUT array elements 2 can be selected to replace the original PMUT array elements 2 according to different detection scenarios, so as to change the shape and function of the PMUT array ultrasonic transducer. For example, a planar PMUT array ultrasonic transducer can be replaced by a curved PMUT array ultrasonic transducer to meet the needs of a curved probe; or a normal PMUT array element 2 can be replaced by a PMUT array element 2 with special functions, such as temperature sensing, pressure sensing, optical sensing, etc., to realize multi-modal ultrasonic imaging and detection.

[0039] For example, by screening and replacing single elements with the same frequency or variable frequency and high frequency accuracy, a high-performance PMUT array transducer can be formed, so as to improve the frequency uniformity of the elements in the single-frequency transducer; and the different elements in the transducer can be precisely controlled to different frequencies to realize the function of variable frequency. The pre-screening of elements to form an array can avoid the problem of large deviation of the working frequency of the elements in the integrated single-frequency PMUT array ultrasonic transducer due to process deviation.

[0040] In an exemplary embodiment, as shown in Figure 2 and Figure 3As shown, the PMUT array 2 is detachably joined to the patch area 11 by an adhesive 4, and the adhesive 4 is capable of being heated and melted. The adhesive 4 is used as a connecting medium between the PMUT array 2 and the patch area 11, so that the PMUT array 2 is detachably joined to the patch area 11, and the adhesive 4 is capable of being heated and melted, thereby realizing the replaceability of the PMUT array 2.

[0041] The aforementioned adhesive 4 is a reversible thermoplastic glue (such as an acrylic modified epoxy resin), that is, it has certain viscosity and hardness at room temperature, can firmly join the PMUT array 2 to the patch area 11, and ensure the mechanical connection of the PMUT array 2; and when heated to a certain temperature, the adhesive 4 will become soft or melt, lose viscosity and hardness, and the PMUT array 2 can be detached from the patch area 11, realizing the detachability of the PMUT array 2. When the adhesive 4 cools to room temperature, the adhesive 4 will restore its original viscosity and hardness, and the PMUT array 2 can be re-joined to the patch area 11, or other PMUT array 2 can be joined to the patch area 11, realizing the replaceability of the PMUT array 2.

[0042] In other embodiments, the combination of the PMUT array 2 and the patch area 11 can be embedded, structure printing or other detachable joining methods.

[0043] In an exemplary embodiment, as shown in Figure 4 The PMUT array 2 includes a chip layer 21, and a lower electrode 22, a piezoelectric layer 23 and an upper electrode 24 sequentially stacked on the upper surface of the chip layer 21 from bottom to top.

[0044] The chip layer 21 can be made of a semiconductor material (such as silicon), serving as the foundation and support structure of the entire PMUT array 2. The chip layer 21 can provide stable mechanical support for the lower electrode 22, the piezoelectric layer 23 and the upper electrode 24. The chip layer 21 has a suspended area, that is, a circular or other shaped cavity, which cooperates with the lower electrode 22, the piezoelectric layer 23 and the upper electrode 24 to form a diaphragm structure that can be used to emit and receive ultrasonic waves.

[0045] The lower electrode 22 is the lower electrode of the PMUT array 2, which is arranged in the suspended area of the chip layer 21 and closely joined with the chip layer 21, and is used to apply an electric field to the piezoelectric layer 23. The lower electrode 22 can be a metal film, a conductive polymer film, a carbon nanotube film, etc., which can provide good electrical conduction and mechanical connection of the PMUT array 2. The material of the lower electrode 22 can be gold, platinum, aluminum or tin and their alloys.

[0046] The piezoelectric layer 23 is arranged on the upper surface of the lower electrode 22 and is tightly combined with the lower electrode 22, and is used to generate deformation under the action of an electric field or generate an electric field under the action of deformation. The piezoelectric layer 23 can generate mechanical vibration and is used to generate or receive ultrasonic waves. The piezoelectric layer 23 can be a piezoelectric ceramic film, a piezoelectric polymer film, a piezoelectric composite material film, or the like. The piezoelectric layer 23 can be made of aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT) piezoelectric ceramic, scandium-doped aluminum nitride, polyvinylidene fluoride (PVDF), lithium niobate (LiNbO3), quartz, potassium niobate (KNbO3), lithium tantalate (LiTaO3), or the like, and a combination thereof.

[0047] The upper electrode 24 is an upper electrode of the PMUT array element 2, which is arranged on the upper surface of the piezoelectric layer 23 and is tightly combined with the piezoelectric layer 23, and forms an electric field together with the lower electrode 22 to excite the piezoelectric layer 23 to generate vibration. The upper electrode 24 can be a metal film, a conductive polymer film, a carbon nanotube film, or the like, and can provide good electrical conduction of the PMUT array element 2. The upper electrode 24 can be made of gold, platinum, aluminum, tin, or an alloy thereof.

[0048] Specifically, as shown in FIGS. 1, 2, and 3, the chip layer 21 includes a substrate layer 211, an oxidation layer 212, and a support layer 213 which are sequentially stacked from bottom to top, and the substrate layer 211 is provided with a first cavity 214 penetrating through the substrate layer 211. Figure 4 Figure 5 Specifically, as shown in FIGS. 1, 2, and 3, the chip layer 21 includes a substrate layer 211, an oxidation layer 212, and a support layer 213 which are sequentially stacked from bottom to top, and the substrate layer 211 is provided with a first cavity 214 penetrating through the substrate layer 211.

[0049] In this embodiment, the chip layer 21 adopts the structure of SOI CMOS, and the main feature is that the chip layer 21 is formed in a three-layer stacking manner of the substrate layer 211, the oxidation layer 212, and the support layer 213, and has the first cavity 214. The substrate layer 211 is the bottom layer of the chip layer 21, which can be a silicon wafer, a ceramic wafer, or the like, and can provide mechanical support for the chip layer 21. The substrate layer 211 is provided with a first cavity 214 penetrating through the substrate layer 211, i.e., a circular or other shaped hole, for forming a suspended structure.

[0050] The oxidation layer 212 is the middle layer of the chip layer 21, which is arranged on the upper surface of the substrate layer 211 and is tightly combined with the substrate layer 211, and is used to form an insulating buried oxygen layer between the substrate layer 211 and the support layer 213. The buried oxygen layer can be used to isolate circuit components and the substrate layer 211, and avoid latch-up effect and parasitic capacitance. The oxidation layer 212 can be a silicon oxide film, a silicon nitride film, an aluminum oxide film, or the like, and can provide efficient electrical insulation and mechanical connection of SOI CMOS.

[0051] ​The support layer 213 is the top layer of the chip layer 21, which is arranged on the upper surface of the oxide layer 212 and tightly bonded with the oxide layer 212, for forming a thin silicon film on the oxide layer 212, which is the active area of the SOI CMOS and can be used to make circuit components such as transistors, memory cells, diodes, resistors, wires, pins, etc. The support layer 213 can be a single-crystal silicon thin film, a polycrystalline silicon thin film, a silicon-germanium alloy thin film, etc.

[0052] In an exemplary embodiment, as shown in FIG. 1, the patch area 11 is provided with a second cavity 12 penetrating through the PCB substrate 1 at the position corresponding to the first cavity 214, and the first cavity 214 and the second cavity 12 are coaxial to form a communicating cavity structure. Figure 3

[0053] The second cavity 12 is a penetrating area on the PCB substrate 1, i.e. a circular or other shaped hole, and the second cavity 12 can form an air layer which can be used as an auxiliary part of the PMUT array element 2 to enhance the sensitivity and output power of the PMUT array element 2. The shape and size of the second cavity 12 are adapted to the first cavity 214, so that the first cavity 214 and the second cavity 12 are coaxial to form a communicating cavity structure, providing a clear transmission path for the ultrasonic waves, reducing energy scattering and loss, and improving transmission efficiency.

[0054] In an exemplary embodiment, as shown in FIG. 1, the patch area 11 is provided with a second cavity 12 penetrating through the PCB substrate 1 at the position corresponding to the first cavity 214, and the first cavity 214 and the second cavity 12 are coaxial to form a communicating cavity structure. Figure 2

[0055] Specifically, for two identical PMUT array elements 2, the width of the groove structure 3 is w, and the depth of the groove structure 3 is equal to the thickness of the chip layer 21. Wherein, c is the speed of sound, f is the resonance frequency, and a is the width of the chip layer 21. In order to reduce the influence of grating lobes and side lobes, the distance d between the PMUT array elements 2 (the distance between the centers of the array elements) should be the width of half the wavelength of the ultrasonic wave, i.e. The groove width w is designed in this way.

[0056] In an exemplary embodiment, as shown in FIG. 1, the patch area 11 is provided with a second cavity 12 penetrating through the PCB substrate 1 at the position corresponding to the first cavity 214, and the first cavity 214 and the second cavity 12 are coaxial to form a communicating cavity structure. Figure 1 Figure 3 ​​​As shown, the PCB substrate 1 is provided with a plurality of electrode pads 13, and the upper electrode 24 and the lower electrode 22 are electrically connected to the electrode pads 13 through the metal wires 5 to realize the signal input and output of the PMUT array element 2. The electrode pads 13 provide a stable and reliable electrical connection point to ensure the effective transmission of electrical signals.

[0057] Please refer to Figure 6 As shown, it is an embedded PMUT array ultrasonic transducer in an embodiment of the present application, wherein the patch area 11 of the PCB substrate 1 is a groove structure, and the PMUT array element 2 is embedded in the groove of the patch area 11.

[0058] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0059] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be combined to form other embodiments that those skilled in the art can understand.

Claims

1. A PMUT array ultrasonic transducer, characterized in that, include: A PCB substrate, wherein multiple patch areas are arranged in an array on the PCB substrate; Multiple independent PMUT array elements are provided, each PMUT array element being detachably attached to the patch area, and each PMUT array element corresponding to a patch area. The PMUT array element includes a chip layer, which includes a substrate layer, an oxide layer and a support layer stacked sequentially from bottom to top. The substrate layer has a first cavity penetrating the substrate layer, and the patch area has a second cavity penetrating the PCB substrate corresponding to the first cavity. The first cavity and the second cavity are coaxial.

2. The PMUT array ultrasonic transducer as described in claim 1, characterized in that, The PMUT array element is detachably attached to the patch area by an adhesive that can be heated to melt.

3. The PMUT array ultrasonic transducer as described in claim 1, characterized in that, The PMUT array element includes a lower electrode, a piezoelectric layer, and an upper electrode, which are stacked sequentially from bottom to top on the upper surface of the chip layer.

4. The PMUT array ultrasonic transducer as described in claim 3, characterized in that, The substrate layer is a silicon wafer, the oxide layer is a silicon dioxide layer, and the support layer is a monocrystalline silicon layer.

5. The PMUT array ultrasonic transducer as described in claim 3, characterized in that, A groove structure is formed between any two adjacent PMUT array elements.

6. The PMUT array ultrasonic transducer as described in claim 5, characterized in that, The width of the trench structure is w, and the depth of the trench structure is equal to the thickness of the chip layer; in, c is the speed of sound, f is the resonant frequency, and a is the width of the chip layer.

7. The PMUT array ultrasonic transducer as described in claim 3, characterized in that, The PCB substrate has multiple electrode pads, and the upper electrode and the lower electrode are electrically connected to the electrode pads via metal wires.

8. The PMUT array ultrasonic transducer as described in claim 3, characterized in that, The upper electrode is made of gold, the lower electrode is made of molybdenum, and the piezoelectric layer is made of scandium-doped aluminum nitride.

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