Manufacturing method of MEMS ultrasonic transducer

Abstract

The embodiment of the invention discloses a manufacturing method of an MEMS ultrasonic transducer. The MEMS ultrasonic transducer comprises a substrate, a vibrating diaphragm, a bottom electrode layer, a piezoelectric layer and a top electrode layer, the substrate comprises a through hole and a supporting area; the vertical projection of the vibrating diaphragm on the substrate covers the through hole and part of the supporting area; the bottom electrode layer comprises an inner-ring bottom electrode and an outer-ring bottom electrode, the piezoelectric layer comprises an inner-ring piezoelectric layer and an outer-ring piezoelectric layer, all the layers are stacked in sequence, and the bottom electrode layer and the outer-ring part of the piezoelectric layer surround the inner-ring part and cover part of the through hole and the supporting area of the substrate. The top electrode layer comprises an inner-ring top electrode and an outer-ring top electrode, and a gap is formed between the inner-ring top electrode and the outer-ring top electrode; the outer-ring top electrode surrounds the inner-ring top electrode, the vertical projection of the inner-ring top electrode on the piezoelectric layer is located in the inner-ring piezoelectric layer, and the vertical projection of the outer-ring top electrode on the piezoelectric layer is located in the outer-ring piezoelectric layer; the outer ring top electrode is electrically connected with the inner ring bottom electrode, and the outer ring bottom electrode is electrically connected with the inner ring top electrode. The process difficulty and the production cost can be reduced, and the performance of the transducer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems, and in particular to a method for manufacturing a MEMS ultrasonic transducer. Background Art

[0002] Piezoelectric Micromachined Ultrasonic Transducer (pMUT) based on Micro-Electro-Mechanical System (MEMS) technology is an important device that can be used in application fields such as robot obstacle avoidance, ultrasonic gesture recognition, ultrasonic under-screen fingerprint recognition, and ultrasonic imaging.

[0003] In order to expand the scope of application, pMUT devices need better performance, that is, they can have greater transmission / reception sensitivity for the same signal. At present, it can be optimized by optimizing the upper electrode coverage area (usually about 60% of the overall size of the diaphragm, which can be optimized through simulation), etching lead zirconate titanate (PZT) to release stress, using differential electrodes, etc. It can also be optimized by combining multiple methods, but it will increase the complexity of the process flow and the back-end application system. The market's requirements for MEMS devices focus more on cost and versatility of application. Therefore, it is necessary to develop a pMUT device with the same application difficulty as the current device, controllable process difficulty and cost, and better performance. Summary of the invention

[0004] The present invention provides a method for manufacturing a MEMS ultrasonic transducer, which can improve the performance of the transducer while ensuring that the transducer has lower manufacturing process difficulty and production cost.

[0005] According to one aspect of the present invention, there is provided a MEMS ultrasonic transducer, comprising:

[0006] A substrate, and a diaphragm, a bottom electrode layer, a piezoelectric layer and a top electrode layer stacked in sequence on one side of the substrate; the diaphragm is arranged on a side of the bottom electrode layer adjacent to the substrate;

[0007] The substrate includes a through hole and a support area surrounding the through hole;

[0008] The vertical projection of the diaphragm on the substrate covers the through hole and at least a part of the supporting area;

[0009] The bottom electrode layer comprises an inner bottom electrode and an outer bottom electrode, a gap is provided between the inner bottom electrode and the outer bottom electrode, and the outer bottom electrode surrounds the inner bottom electrode; a vertical projection of the inner bottom electrode on the substrate is located in the through hole, and a vertical projection of the outer bottom electrode on the substrate covers a part of the through hole and at least a part of the support area;

[0010] The piezoelectric layer comprises an inner piezoelectric layer and an outer piezoelectric layer, wherein a gap is provided between the inner piezoelectric layer and the outer piezoelectric layer, and the outer piezoelectric layer surrounds the inner piezoelectric layer; a vertical projection of the inner piezoelectric layer on the bottom electrode layer is located inside the inner bottom electrode, and a vertical projection of the outer piezoelectric layer on the substrate covers a portion of the through hole and at least a portion of the support area;

[0011] The top electrode layer includes an inner ring top electrode and an outer ring top electrode, and a gap is provided between the inner ring top electrode and the outer ring top electrode; the outer ring top electrode surrounds the inner ring top electrode, and a vertical projection of the inner ring top electrode on the piezoelectric layer is located inside the inner ring piezoelectric layer, and a vertical projection of the outer ring top electrode on the piezoelectric layer is located inside the outer ring piezoelectric layer;

[0012] The outer ring top electrode is electrically connected to the inner ring bottom electrode, and the outer ring bottom electrode is electrically connected to the inner ring top electrode.

[0013] Optionally, the MEMS ultrasonic transducer also includes:

[0014] The insulating layer covers the gap between the inner circle bottom electrode and the outer circle bottom electrode, and at least a part of the gap between the inner circle piezoelectric layer and the outer circle piezoelectric layer.

[0015] Optionally, the outer ring top electrode further has an opening, the opening penetrates the outer ring top electrode in a direction from the outer ring top electrode to the inner ring top electrode, and the insulating layer also covers the piezoelectric layer at the opening;

[0016] A first signal line and a second signal line are arranged on a surface of the insulating layer at the opening away from the substrate; a first end of the first signal line is electrically connected to the inner circle bottom electrode through a first through hole in the insulating layer at the gap, or a portion of the inner circle bottom electrode is exposed between a first edge of the insulating layer at the gap adjacent to the inner circle piezoelectric layer and the inner circle piezoelectric layer, and a first end of the first signal line crosses the first edge and contacts and is electrically connected to the inner circle bottom electrode at the exposed portion; a second end of the first signal line is electrically connected to the outer circle top electrode;

[0017] The first end of the second signal line is electrically connected to the inner ring top electrode, the second end of the second signal line is located on the side of the outer ring top electrode away from the inner ring top electrode, and the second end of the second signal line is electrically connected to the outer ring bottom electrode through a second through hole in the piezoelectric layer.

[0018] Optionally, the MEMS ultrasonic transducer also includes:

[0019] a first external pin and a second external pin;

[0020] The first external pin and the second external pin are located on a side of the piezoelectric layer away from the substrate, and are located on a side of the outer ring top electrode away from the inner ring top electrode;

[0021] The first signal line is electrically connected to the first external pin, and the second signal line is electrically connected to the second external pin.

[0022] Optionally, the first signal line, the second signal line, the first external pin and the second external pin are all located in the top electrode layer and are made of the same material as the top electrode layer.

[0023] Optionally, the substrate includes a silicon substrate layer and a silicon dioxide layer, and the silicon dioxide layer is arranged on a side of the silicon substrate layer adjacent to the diaphragm.

[0024] According to another aspect of the present invention, there is provided a method for manufacturing a MEMS ultrasonic transducer, comprising:

[0025] providing a base material layer;

[0026] A bottom electrode layer, a piezoelectric layer and a top electrode layer are arranged on the surface of the base material layer; wherein the bottom electrode layer, the piezoelectric layer and the top electrode layer are stacked in sequence, and the piezoelectric layer is arranged on a side of the bottom electrode layer away from the base material layer;

[0027] Patterning the surface of the substrate material layer away from the bottom electrode layer to form a substrate with through holes and a support area and a diaphragm;

[0028] The support area surrounds the through hole, and the diaphragm is arranged on a side of the substrate adjacent to the bottom electrode layer; the vertical projection of the diaphragm on the substrate covers the through hole and at least part of the support area;

[0029] The bottom electrode layer comprises an inner bottom electrode and an outer bottom electrode, a gap is provided between the inner bottom electrode and the outer bottom electrode, and the outer bottom electrode surrounds the inner bottom electrode; a vertical projection of the inner bottom electrode on the substrate is located in the through hole, and a vertical projection of the outer bottom electrode on the substrate covers a part of the through hole and at least a part of the support area;

[0030] The piezoelectric layer comprises an inner piezoelectric layer and an outer piezoelectric layer, wherein a gap is provided between the inner piezoelectric layer and the outer piezoelectric layer, and the outer piezoelectric layer surrounds the inner piezoelectric layer; a vertical projection of the inner piezoelectric layer on the bottom electrode layer is located inside the inner bottom electrode, and a vertical projection of the outer piezoelectric layer on the substrate covers a portion of the through hole and at least a portion of the support area;

[0031] The top electrode layer includes an inner ring top electrode and an outer ring top electrode, and a gap is provided between the inner ring top electrode and the outer ring top electrode; the outer ring top electrode surrounds the inner ring top electrode, and a vertical projection of the inner ring top electrode on the piezoelectric layer is located inside the inner ring piezoelectric layer, and a vertical projection of the outer ring top electrode on the piezoelectric layer is located inside the outer ring piezoelectric layer;

[0032] The outer ring top electrode is electrically connected to the inner ring bottom electrode, and the outer ring bottom electrode is electrically connected to the inner ring top electrode.

[0033] Optionally, a bottom electrode layer, a piezoelectric layer and a top electrode layer are arranged on the surface of the base material layer, including:

[0034] Disposing a bottom electrode material layer on the surface of the base material layer;

[0035] Disposing a piezoelectric material layer on the surface of the bottom electrode material layer;

[0036] patterning the piezoelectric material layer to form a piezoelectric layer;

[0037] Patterning the bottom electrode material layer to form a bottom electrode layer;

[0038] An insulating layer is provided; wherein the insulating layer covers the gap between the inner circle bottom electrode and the outer circle bottom electrode, and at least a part of the gap between the inner circle piezoelectric layer and the outer circle piezoelectric layer;

[0039] Disposing a top electrode material layer on the surface of the piezoelectric layer;

[0040] The top electrode material layer is patterned to form a top electrode layer.

[0041] Optionally, patterning the top electrode material layer to form the top electrode layer includes:

[0042] Etching the top electrode material layer to form an inner ring top electrode, an outer ring top electrode, a first signal line, a second signal line, a first external pin and a second external pin;

[0043] The outer ring top electrode has an opening, the opening penetrates the outer ring top electrode in a direction from the outer ring top electrode to the inner ring top electrode, and the insulating layer also covers the piezoelectric layer at the opening;

[0044] The first signal line and the second signal line are arranged on the surface of the insulating layer at the opening away from the substrate, the first end of the first signal line is electrically connected to the inner circle bottom electrode through the first through hole in the insulating layer at the gap, or, the insulating layer at the gap is adjacent to the first edge of the inner circle piezoelectric layer and a portion of the inner circle bottom electrode is exposed between the inner circle piezoelectric layer, the first end of the first signal line crosses the first edge and contacts and is electrically connected to the inner circle bottom electrode at the exposed portion; the second end of the first signal line is electrically connected to the outer circle top electrode;

[0045] The first end of the second signal line is electrically connected to the inner ring top electrode, the second end of the second signal line is located on a side of the outer ring top electrode away from the inner ring top electrode, and the second end of the second signal line is electrically connected to the outer ring bottom electrode through a second through hole in the piezoelectric layer;

[0046] The first external pin and the second external pin are located on the side of the piezoelectric layer away from the substrate and on the side of the outer ring top electrode away from the inner ring top electrode; the first signal line is electrically connected to the first external pin, and the second signal line is electrically connected to the second external pin.

[0047] Optionally, the base material layer includes a first silicon layer, a silicon dioxide layer, and a second silicon layer which are stacked, and the second silicon layer is arranged on a side of the silicon dioxide layer adjacent to the bottom electrode layer;

[0048] Patterning the surface of the substrate material layer away from the bottom electrode layer to form a substrate with through holes and a support area and a diaphragm includes:

[0049] thinning the first silicon layer;

[0050] The first silicon layer and the silicon dioxide layer are etched respectively to form a substrate with through holes and a support area and a diaphragm; wherein the substrate includes the first silicon layer with through holes and the silicon dioxide layer with through holes.

[0051] The MEMS ultrasonic transducer provided in the embodiment of the present invention provides a stable support structure for the diaphragm by setting a through hole and a support area surrounding the through hole on the substrate, and ensuring that the vertical projection of the diaphragm on the substrate covers the through hole and at least part of the support area. The diaphragm is prevented from collapsing or deforming during vibration, and the structural stability and service life of the transducer are improved. The bottom electrode layer, the piezoelectric layer and the top electrode layer are divided into an inner ring and an outer ring, and the outer ring part surrounds the inner ring part. The outer ring top electrode and the inner ring bottom electrode are electrically connected, and the outer ring bottom electrode and the inner ring top electrode are electrically connected, so that when an AC signal is input, there is always a reverse electric field with a phase difference of 180° in the piezoelectric layers of the inner and outer rings. Therefore, the drive of the differential pMUT can be realized without increasing the number of electrode pad pairs and the complexity of the driving circuit, thereby meeting the requirements of higher performance, controllable cost, and the same application complexity as existing devices.

[0052] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0054] Figure 1 1 is a top view of a MEMS ultrasonic transducer provided by an embodiment of the present invention.

[0055] Figure 2 yes Figure 1 Cross-sectional view of the MEMS ultrasonic transducer along the AA' section line.

[0056] Figure 3 This is a traditional non-differential single-electrode pMUT diagram.

[0057] Figure 4 yes Figure 3 Corresponding vibration simulation diagram.

[0058] Figure 5 This is the inside-outside differential dual-electrode pMUT diagram.

[0059] Figure 6 yes Figure 5 Corresponding vibration simulation diagram.

[0060] Figure 7 The present invention provides a MEMS ultrasonic transducer with reverse interconnection of upper and lower electrodes inside and outside, a driving signal and a distribution diagram of the internal electric field.

[0061] Figure 8 It is a flow chart of a method for manufacturing a MEMS ultrasonic transducer provided in an embodiment of the present invention.

[0062] Fig. 9 It is a structural diagram of a transducer after the base material layer is manufactured according to an embodiment of the present invention.

[0063] Fig.10 It is a structural diagram of a transducer after the bottom electrode material layer is manufactured according to an embodiment of the present invention.

[0064] Fig.11 It is a structural diagram of a transducer after the piezoelectric material layer is manufactured according to an embodiment of the present invention.

[0065] Fig.12 It is a structural diagram of a transducer after the piezoelectric layer is manufactured according to an embodiment of the present invention.

[0066] Fig.13 It is a schematic diagram of the etched piezoelectric layer provided in an embodiment of the present invention.

[0067] Fig.14 It is a structural diagram of a transducer after the bottom electrode layer is manufactured according to an embodiment of the present invention.

[0068] Fig.15 It is a schematic diagram of the etched bottom electrode provided by an embodiment of the present invention.

[0069] Fig.16 It is a structural diagram of a transducer after the insulating layer is manufactured according to an embodiment of the present invention.

[0070] Fig.17 It is a schematic diagram of an insulating layer provided by an embodiment of the present invention.

[0071] Fig.18 It is a structural diagram of a transducer after the top electrode material layer is manufactured according to an embodiment of the present invention.

[0072] Fig.19 It is a structural diagram of a transducer after the top electrode layer is manufactured according to an embodiment of the present invention.

[0073] Fig. 20 It is a structural diagram of a transducer after the thinning layer provided by an embodiment of the present invention.

[0074] Fig.21 It is a schematic diagram of the first silicon layer and the silicon dioxide layer being etched away provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0075] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0076] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0077] An embodiment of the present invention provides a MEMS ultrasonic transducer. Figure 1 1 is a top view of a MEMS ultrasonic transducer provided by an embodiment of the present invention. Figure 2 yes Figure 1 The cross-sectional view of the MEMS ultrasonic transducer along the AA' section line. Figure 1-Figure 2 , MEMS ultrasonic transducers include:

[0078] A substrate 10, and a diaphragm 20, a bottom electrode layer 30, a piezoelectric layer 40 and a top electrode layer 50 which are sequentially stacked and arranged on one side of the substrate 10; the diaphragm 20 is arranged on a side of the bottom electrode layer 30 adjacent to the substrate 10;

[0079] The substrate 10 includes a through hole 11 and a supporting area 12 surrounding the through hole 11;

[0080] The vertical projection of the diaphragm 20 on the substrate 10 covers the through hole 11 and at least a part of the supporting area 12;

[0081] The bottom electrode layer 30 includes an inner bottom electrode 31 and an outer bottom electrode 32, wherein a gap is provided between the inner bottom electrode 31 and the outer bottom electrode 32, and the outer bottom electrode 32 surrounds the inner bottom electrode 31; the vertical projection of the inner bottom electrode 31 on the substrate 10 is located in the through hole 11, and the vertical projection of the outer bottom electrode 32 on the substrate 10 covers a part of the through hole 11 and at least a part of the support area 12;

[0082] The piezoelectric layer 40 includes an inner piezoelectric layer 41 and an outer piezoelectric layer 42, wherein a gap is provided between the inner piezoelectric layer 41 and the outer piezoelectric layer 42, and the outer piezoelectric layer 42 surrounds the inner piezoelectric layer 41; a vertical projection of the inner piezoelectric layer 41 on the bottom electrode layer 30 is located inside the inner bottom electrode 31, and a vertical projection of the outer piezoelectric layer 42 on the substrate 10 covers a portion of the through hole 11 and at least a portion of the support area 12;

[0083] The top electrode layer 50 includes an inner ring top electrode 51 and an outer ring top electrode 52, with a gap between the inner ring top electrode 51 and the outer ring top electrode 52; the outer ring top electrode 52 surrounds the inner ring top electrode 51, the vertical projection of the inner ring top electrode 51 on the piezoelectric layer 40 is located inside the inner ring piezoelectric layer 41, and the vertical projection of the outer ring top electrode 52 on the piezoelectric layer 40 is located inside the outer ring piezoelectric layer 42;

[0084] The outer ring top electrode 52 is electrically connected to the inner ring bottom electrode 31 , and the outer ring bottom electrode 32 is electrically connected to the inner ring top electrode 51 .

[0085] The working principle of the pMUT device is related to the piezoelectric effect of the piezoelectric film layer. When the piezoelectric effect is positive, that is, the diaphragm receives sound waves, the ultrasonic wave causes the diaphragm to vibrate, and continuously produces up and down reciprocating deformation, periodically stretching / compressing the piezoelectric layer, causing the piezoelectric layer to generate electric charge, and connected to the outside through the upper and lower electrodes, and the external circuit can receive the changing charge signal; when the piezoelectric effect is reversed, the external circuit passes a high-frequency alternating voltage (such as a sine wave) through the upper and lower electrodes, and the upper and lower electrodes generate an alternating electric field in the piezoelectric layer. The electric field causes the piezoelectric layer to produce stretching / compression deformation, thereby causing the piezoelectric layer to drive the diaphragm to vibrate and generate sound waves.

[0086] Figure 3 This is a traditional non-differential single-electrode pMUT diagram. Figure 4 yes Figure 3 Corresponding vibration simulation diagram. Figure 5 This is the inside-outside differential dual-electrode pMUT diagram. Figure 6 yes Figure 5 Corresponding vibration simulation diagram. Figure 3-Figure 6To achieve differential voltage drive, two sets of reverse driving signal inputs are required, that is, the electric field of the inner electrode must be opposite to that of the outer electrode. Therefore, two pairs of electrode pads and two driving signals are required to be input to the inner and outer piezoelectric layers respectively. pMUT uses differential electrodes, that is, reverse electric fields are applied to the inside and outside respectively. Through piezoelectric principles and simulations, it can be seen that the differential structure can achieve nearly double the sensitivity under the same driving voltage compared to the ordinary single electrode structure.

[0087] Figure 7 This is a diagram of the reverse interconnection of the upper and lower electrodes inside and outside a MEMS ultrasonic transducer, the driving signal, and the distribution of the internal electric field provided by an embodiment of the present invention. Figure 7 By etching the bottom electrode layer, the inner circle bottom electrode and the outer circle bottom electrode are separated, and by constructing an insulating layer, the inner circle top electrode is connected to the outer circle bottom electrode, and the outer circle top electrode is connected to the inner circle bottom electrode. Therefore, when an AC signal is input, there is always a reverse electric field with a phase difference of 180° in the inner circle piezoelectric layer and the outer circle piezoelectric layer. Therefore, the driving of the differential pMUT can be realized without increasing the number of electrode pad pairs and the complexity of the driving circuit, thereby meeting the requirements of higher performance, controllable cost, and the same application complexity as existing devices.

[0088] Specifically, by providing a through hole and a support area surrounding the through hole on the substrate 10, sufficient support can be provided for the diaphragm, while reducing the obstruction of the diaphragm vibration by the substrate 10. The vertical projection of the diaphragm on the substrate 10 covers the through hole and at least part of the support area, which helps to increase the effective vibration area of ​​the diaphragm, thereby enhancing the transmission and reception performance of ultrasonic waves. The bottom electrode layer 30 includes an inner circle bottom electrode 31 and an outer circle bottom electrode 32, the piezoelectric layer 40 includes an inner circle piezoelectric layer 41 and an outer circle piezoelectric layer 42, and the top electrode layer 50 includes an inner circle top electrode 51 and an outer circle top electrode 52, all of which are designed as inner and outer circle structures, the inner circle bottom electrode 31 and the outer circle bottom electrode 32 are made of the same material in the same layer, the inner circle piezoelectric layer 41 and the outer circle piezoelectric layer 42 are made of the same material in the same layer, and the inner circle top electrode 51 and the outer circle top electrode 52 are made of the same material in the same layer, which all reduce production costs, the inner circle bottom electrode 31 and the outer circle bottom electrode 32 are manufactured in the same process flow, the inner circle piezoelectric layer 41 and the outer circle piezoelectric layer 42 are manufactured in the same process flow, and the inner circle top electrode 51 and the outer circle top electrode 52 are manufactured in the same process flow, thereby simplifying the process flow.

[0089] The MEMS ultrasonic transducer provided in the embodiment of the present invention provides a stable support structure for the diaphragm 20 by setting a through hole 11 and a support area 12 surrounding the through hole 11 on the substrate 10, and ensuring that the vertical projection of the diaphragm 20 on the substrate 10 covers the through hole 11 and at least part of the support area 12. The diaphragm 20 is prevented from collapsing or deforming during the vibration process, and the structural stability and service life of the transducer are improved. The bottom electrode layer 30, the piezoelectric layer 40 and the top electrode layer 50 are divided into an inner circle and an outer circle, and the outer circle part surrounds the inner circle part. The outer circle top electrode 52 is electrically connected to the inner circle bottom electrode 31, and the outer circle bottom electrode 32 is electrically connected to the inner circle top electrode 51, so that when an AC signal is input, there is always a reverse electric field with a phase difference of 180° in the piezoelectric layers of the inner and outer circles. Therefore, the drive of the differential pMUT can be realized without increasing the number of electrode pad pairs and the complexity of the driving circuit, thereby meeting the requirements of higher performance, controllable cost, and the same application complexity as the existing devices.

[0090] Continue to refer Figure 1 and Figure 2 , MEMS ultrasonic transducer, also includes:

[0091] The insulating layer 60 covers the gap between the inner circle bottom electrode 31 and the outer circle bottom electrode 32 , and at least a portion of the gap between the inner circle piezoelectric layer 41 and the outer circle piezoelectric layer 42 .

[0092] Specifically, the insulating layer 60 can effectively isolate the inner ring bottom electrode 31 from the outer ring bottom electrode 32 and the inner ring piezoelectric layer 41 from the outer ring piezoelectric layer 42, prevent the current from flowing in the area where it should not flow, and improve the electrical isolation performance of the entire ultrasonic transducer. The insulating layer 60 not only plays the role of electrical isolation, but also serves as a structural support layer to enhance the overall structural stability of the ultrasonic transducer. It helps to prevent unnecessary displacement or deformation between the inner ring bottom electrode 31 and the outer ring bottom electrode 32 under vibration or external force, thereby extending the service life of the ultrasonic transducer, achieving more efficient sound wave transmission and reception, and improving the sensitivity and resolution of the ultrasonic transducer.

[0093] Optionally, the outer ring top electrode 52 further has an opening, and the opening penetrates the outer ring top electrode 52 in a direction from the outer ring top electrode 52 to the inner ring top electrode 51 , and the insulating layer 60 also covers the piezoelectric layer 40 at the opening;

[0094] The surface of the insulating layer 60 at the opening away from the substrate 10 is provided with a first signal line 61 and a second signal line 62; the first end of the first signal line 61 is electrically connected to the inner circle bottom electrode 31 through the first through hole in the insulating layer 60 at the gap, or, the insulating layer 60 at the gap is adjacent to the first edge of the inner circle piezoelectric layer 41 and a portion of the inner circle bottom electrode 31 is exposed between the inner circle piezoelectric layer 41, and the first end of the first signal line 61 crosses the first edge and contacts and is electrically connected to the inner circle bottom electrode 31 at the exposed portion (such as Figure 1 The second end of the first signal line 61 is electrically connected to the outer ring top electrode 52;

[0095] The first end of the second signal line 62 is electrically connected to the inner ring top electrode 51, and the second end of the second signal line 62 is located on the side of the outer ring top electrode 52 away from the inner ring top electrode 51. The second end of the second signal line 62 is electrically connected to the outer ring bottom electrode 32 through the second through hole 80 in the piezoelectric layer 40.

[0096] Specifically, the first end of the first signal line 61 is electrically connected to the inner circle bottom electrode 31 through the first through hole in the insulating layer 60 at the gap, and the signal on the first signal line 61 can be directly transmitted to the inner circle bottom electrode 31. The second end of the first signal line 61 is electrically connected to the outer circle top electrode 52, forming a signal path from the inner circle bottom electrode 31 to the outer circle top electrode 52. The first end of the second signal line 62 is electrically connected to the inner circle top electrode 51, and the second end of the second signal line 62 is electrically connected to the outer circle bottom electrode 32 through the second through hole 80 in the piezoelectric layer 40. Another signal path from the inner circle top electrode 51 to the outer circle bottom electrode 32 is formed. When the signals are transmitted through these two paths, they will generate a changing electric field in the piezoelectric layer 40. Due to the piezoelectric effect, the changing electric field will cause mechanical deformation of the piezoelectric layer 40, thereby generating ultrasonic waves. In this way, the MEMS ultrasonic transducer can convert the input electrical signal into ultrasonic waves and radiate them outward through its structure.

[0097] Optionally, the MEMS ultrasonic transducer also includes:

[0098] A first external pin 71 and a second external pin 72;

[0099] The first external pin 71 and the second external pin 72 are located on a side of the piezoelectric layer 40 away from the substrate 10 , and are located on a side of the outer ring top electrode 52 away from the inner ring top electrode 51 ;

[0100] The first signal line 61 is electrically connected to the first external pin 71 , and the second signal line 62 is electrically connected to the second external pin 72 .

[0101] Specifically, the first external pin 71 and the second external pin 72 are located on a side of the piezoelectric layer 40 away from the substrate 10 , and are located on a side of the outer ring top electrode 52 away from the inner ring top electrode 51 .

[0102] Optionally, the first signal line 61 , the second signal line 62 , the first external pin 71 , and the second external pin 72 are all located in the top electrode layer 50 , and are made of the same material as the top electrode layer 50 .

[0103] Specifically, the first signal line 61, the second signal line 62, the first external pin 71, and the second external pin 72 are all located in the top electrode layer 50, which can enhance the overall structural stability of the transducer, optimize the spatial layout of the transducer, and improve the integration. The first signal line 61, the second signal line 62, the first external pin 71, and the second external pin 72 are all made of the same material as the top electrode layer 50 and are made in the same process flow, which can simplify the manufacturing process of the transducer, reduce manufacturing costs, and improve production efficiency.

[0104] Continue to refer Figure 2 The substrate 10 includes a silicon substrate layer 111 and a silicon dioxide layer 103 . The silicon dioxide layer 103 is disposed on a side of the silicon substrate layer 111 adjacent to the diaphragm 20 .

[0105] Specifically, the silicon dioxide layer 103, as an insulating layer, can isolate the electrical signal interference between the silicon substrate layer 111 and the diaphragm 20, reduce the parasitic capacitance formed between the silicon substrate layer 111 and the diaphragm 20, reduce the noise level and power consumption of the transducer, and improve the overall structural stability of the transducer. The silicon dioxide layer 103 also has a certain mechanical strength, which can support the stability of the diaphragm under high-frequency vibration and extend the service life of the transducer.

[0106] The embodiment of the present invention also provides a flow chart of a method for manufacturing a MEMS ultrasonic transducer. Figure 8 is a flowchart of a method for manufacturing a MEMS ultrasonic transducer provided by an embodiment of the present invention, with reference to Figure 8 The manufacturing method of the MEMS ultrasonic transducer comprises the following steps:

[0107] S310, providing a base material layer;

[0108] in, Fig. 9 FIG. 1 is a diagram showing the structure of a transducer after the base material layer is manufactured according to an embodiment of the present invention. Fig. 9 The base material layer 100 includes a first silicon layer 101 and a second silicon layer 102, wherein a silicon dioxide layer 103 is located between the first silicon layer 101 and the second silicon layer 102. The base material layer 100 may be an SOI substrate, and the thickness of the base material layer 100 is 725 um.

[0109] S320, disposing a bottom electrode layer, a piezoelectric layer and a top electrode layer on the surface of the base material layer; wherein the bottom electrode layer, the piezoelectric layer and the top electrode layer are stacked in sequence, and the piezoelectric layer is disposed on a side of the bottom electrode layer away from the base material layer;

[0110] S330, patterning the surface of the substrate material layer away from the bottom electrode layer to form a substrate having through holes and a support area and a diaphragm;

[0111] The support area surrounds the through hole, and the diaphragm is arranged on a side of the substrate adjacent to the bottom electrode layer; the vertical projection of the diaphragm on the substrate covers the through hole and at least part of the support area;

[0112] The bottom electrode layer comprises an inner bottom electrode and an outer bottom electrode, a gap is provided between the inner bottom electrode and the outer bottom electrode, and the outer bottom electrode surrounds the inner bottom electrode; a vertical projection of the inner bottom electrode on the substrate is located in the through hole, and a vertical projection of the outer bottom electrode on the substrate covers a part of the through hole and at least a part of the support area;

[0113] The piezoelectric layer comprises an inner piezoelectric layer and an outer piezoelectric layer, wherein a gap is provided between the inner piezoelectric layer and the outer piezoelectric layer, and the outer piezoelectric layer surrounds the inner piezoelectric layer; a vertical projection of the inner piezoelectric layer on the bottom electrode layer is located inside the inner bottom electrode, and a vertical projection of the outer piezoelectric layer on the substrate covers a portion of the through hole and at least a portion of the support area;

[0114] The top electrode layer includes an inner ring top electrode and an outer ring top electrode, and a gap is provided between the inner ring top electrode and the outer ring top electrode; the outer ring top electrode surrounds the inner ring top electrode, and a vertical projection of the inner ring top electrode on the piezoelectric layer is located inside the inner ring piezoelectric layer, and a vertical projection of the outer ring top electrode on the piezoelectric layer is located inside the outer ring piezoelectric layer;

[0115] The outer ring top electrode is electrically connected to the inner ring bottom electrode, and the outer ring bottom electrode is electrically connected to the inner ring top electrode.

[0116] The MEMS ultrasonic transducer provided in the embodiment of the present invention provides a stable support structure for the diaphragm by setting a through hole and a support area surrounding the through hole on the substrate, and ensuring that the vertical projection of the diaphragm on the substrate covers the through hole and at least part of the support area. The diaphragm is prevented from collapsing or deforming during vibration, and the structural stability and service life of the transducer are improved. The bottom electrode layer, the piezoelectric layer and the top electrode layer are divided into an inner ring and an outer ring, and the outer ring part surrounds the inner ring part. The outer ring top electrode and the inner ring bottom electrode are electrically connected, and the outer ring bottom electrode and the inner ring top electrode are electrically connected, so that when an AC signal is input, there is always a reverse electric field with a phase difference of 180° in the piezoelectric layers of the inner and outer rings. Therefore, the drive of the differential pMUT can be realized without increasing the number of electrode pad pairs and the complexity of the driving circuit, thereby meeting the requirements of higher performance, controllable cost, and the same application complexity as existing devices.

[0117] Fig.10 FIG. 1 is a diagram showing the structure of a transducer after the bottom electrode material layer is fabricated according to an embodiment of the present invention. Fig.10 Optionally, a bottom electrode layer, a piezoelectric layer and a top electrode layer are arranged on the surface of the base material layer, including:

[0118] A bottom electrode material layer 200 is disposed on the surface of the base material layer 100;

[0119] A piezoelectric material layer 300 is disposed on the surface of the bottom electrode material layer 200;

[0120] Patterning the piezoelectric material layer 300 to form a piezoelectric layer 40;

[0121] Patterning the bottom electrode material layer 200 to form a bottom electrode layer 30;

[0122] An insulating layer 60 is provided; wherein the insulating layer 60 covers the gap between the inner circle bottom electrode 31 and the outer circle bottom electrode 32, and at least a part of the gap between the inner circle piezoelectric layer 41 and the outer circle piezoelectric layer 42;

[0123] A top electrode material layer 400 is disposed on the surface of the piezoelectric layer 40;

[0124] The top electrode material layer 400 is patterned to form a top electrode layer 50 .

[0125] The material of the bottom electrode material layer 200 is Pt, the thickness of the bottom electrode material layer 200 is 200 nm, and the bottom electrode material layer 200 can be grown on the surface of the base material layer 100 by magnetron radio frequency sputtering. Fig.11 FIG. 1 is a diagram showing the structure of a transducer after the piezoelectric material layer is manufactured according to an embodiment of the present invention. Fig.11 The piezoelectric material layer 300 is a PZT piezoelectric film, and the thickness of the piezoelectric material layer 300 is 2 um. The piezoelectric material layer 300 can be grown on the surface of the bottom electrode material layer 200 by magnetron radio frequency sputtering. Fig.12 It is a structural diagram of a transducer after the piezoelectric layer is manufactured according to an embodiment of the present invention. Fig.13 Schematic diagram of the etched piezoelectric layer provided by an embodiment of the present invention. Figure 11-13 The piezoelectric material layer 300 may be patterned to form the piezoelectric layer 40 through photolithography, development, and etching processes. Fig.14 It is a structural diagram of a transducer after the bottom electrode layer is manufactured according to an embodiment of the present invention. Fig.15 Schematic diagram of the bottom electrode etched away according to an embodiment of the present invention. Fig.10 , Fig.14 and Fig.15 The bottom electrode material layer 200 may be patterned through photolithography, development and etching processes to form a bottom electrode layer 30 . Fig.16 It is a structural diagram of a transducer after the insulating layer is manufactured according to an embodiment of the present invention. Fig.17 Schematic diagram of an insulating layer provided by an embodiment of the present invention. Fig.16 and Fig.17, an insulating layer 60 is grown and patterned to cover the short-circuit-prone portions. Fig.18 FIG. 1 is a diagram of a transducer structure after the top electrode material layer is fabricated according to an embodiment of the present invention. Fig.18 The material of the top electrode material layer 400 is Au, the thickness of the top electrode material layer 400 is 200 um, and the top electrode material layer 400 can be grown on the surface of the piezoelectric layer 40 by magnetron radio frequency sputtering.

[0126] Specifically, a layer of conductive material is deposited on the surface of the substrate material layer 100 to form a bottom electrode material layer 200. The bottom electrode material layer 200 will serve as the lower electrode of the piezoelectric material for applying an electric field. A layer of piezoelectric material (such as lead zirconate titanate, aluminum nitride, etc.) is deposited on the surface of the bottom electrode material layer 200 to form a piezoelectric material layer 300. The piezoelectric material will deform under the action of the electric field, thereby generating ultrasonic waves. Through processes such as photolithography and etching, the piezoelectric material layer 300 is patterned into a desired shape and size to form a piezoelectric layer 40, thereby improving the performance of the transducer. The bottom electrode material layer 200 is then patterned to match the shape and size of the piezoelectric layer to form a bottom electrode layer 30. A layer of insulating material (such as silicon dioxide, silicon nitride, etc.) is deposited on the periphery of the bottom electrode layer 30 and the piezoelectric layer 40, and at any gap between the bottom electrode layer 30 and the piezoelectric layer 40 to form an insulating layer 60. The insulating layer 60 is used to prevent short circuits between different electrodes and protect the internal electronic structure to improve the electrical stability and reliability of the transducer. A layer of conductive material is deposited on the surface of the piezoelectric layer 40 to form a top electrode material layer 400. The top electrode material layer 400 will serve as the upper electrode of the piezoelectric material and form an electric field together with the bottom electrode layer 30. The top electrode material layer 400 is patterned to form a top electrode layer 50. The shape and size of the top electrode layer 50 should match the piezoelectric layer to ensure that the electric field is uniformly applied to the piezoelectric layer 40.

[0127] Continue to refer Figure 1 , patterning the top electrode material layer to form a top electrode layer includes:

[0128] The top electrode material layer is etched to form an inner ring top electrode 51, an outer ring top electrode 52, a first signal line 61, a second signal line 62, a first external pin 71 and a second external pin 72;

[0129] The outer ring top electrode 52 has an opening, and the opening penetrates the outer ring top electrode 52 in a direction from the outer ring top electrode 52 to the inner ring top electrode 51, and the insulating layer also covers the piezoelectric layer at the opening;

[0130] The first signal line 61 and the second signal line 62 are arranged on the surface of the insulating layer at the opening away from the substrate, and the first end of the first signal line 61 is electrically connected to the inner circle bottom electrode through the first through hole in the insulating layer at the gap, or, the insulating layer 60 at the gap is adjacent to the first edge of the inner circle piezoelectric layer 41 and a portion of the inner circle bottom electrode 31 is exposed between the inner circle piezoelectric layer 41, and the first end of the first signal line 61 crosses the first edge and contacts and electrically connects to the inner circle bottom electrode 31 at the exposed portion (such as Figure 1 The second end of the first signal line 61 is electrically connected to the outer ring top electrode 52;

[0131] The first end of the second signal line 62 is electrically connected to the inner ring top electrode 51, the second end of the second signal line 62 is located on the side of the outer ring top electrode 52 away from the inner ring top electrode 51, and the second end of the second signal line 62 is electrically connected to the outer ring bottom electrode through the second through hole 80 in the piezoelectric layer;

[0132] The first external pin 71 and the second external pin 72 are located on the side of the piezoelectric layer away from the substrate, and on the side of the outer ring top electrode 52 away from the inner ring top electrode 51; the first signal line 61 is electrically connected to the first external pin 71, and the second signal line 62 is electrically connected to the second external pin 72.

[0133] in, Fig.19 FIG. 1 is a diagram showing the structure of a transducer after the top electrode layer is fabricated according to an embodiment of the present invention. Fig.19 The top electrode material layer is patterned by photolithography, development and etching processes to form an inner ring top electrode 51 and an outer ring top electrode 52, and the outer ring top electrode 52 is electrically connected to the inner ring bottom electrode 31, and the outer ring bottom electrode 32 is electrically connected to the inner ring top electrode 51.

[0134] Specifically, when an external signal is input through the first external pin 71 and the second external pin 72, the external signal will be transmitted along the first signal line 61 and the second signal line 62 respectively. The first signal line 61 transmits the external signal from the first external pin 71 to the outer ring top electrode 52. Since the first end of the first signal line 61 is electrically connected to the inner ring bottom electrode 31 through the first through hole in the insulating layer, the external signal may also be transmitted through the inner ring bottom electrode 31. The second signal line 62 transmits the signal from the inner ring top electrode 51 to the outer ring bottom electrode 32, and its second end is electrically connected to the outer ring bottom electrode 32 through the second through hole 80 in the piezoelectric layer, so as to realize the cross-layer transmission of the signal and improve the utilization rate and transmission efficiency of the signal. When the external signal acts on the piezoelectric layer, the piezoelectric layer will generate corresponding vibration due to the piezoelectric effect. The vibration will be jointly affected by the inner ring top electrode 51, the outer ring top electrode 52 and the bottom electrode layer, forming a complex vibration mode, which can enhance the ultrasonic emission effect or improve the receiving sensitivity. Through the vibration of the piezoelectric layer, the MEMS ultrasonic transducer can emit ultrasonic waves. When external ultrasonic waves act on the transducer, it will also cause the piezoelectric layer to vibrate, and then convert the vibration signal into an electrical signal through the electrode layer and signal line for reception and processing.

[0135] Optionally, the base material layer includes a first silicon layer, a silicon dioxide layer, and a second silicon layer which are stacked, and the second silicon layer is arranged on a side of the silicon dioxide layer adjacent to the bottom electrode layer;

[0136] Patterning the surface of the substrate material layer away from the bottom electrode layer to form a substrate with through holes and a support area and a diaphragm includes:

[0137] thinning the first silicon layer;

[0138] The first silicon layer and the silicon dioxide layer are etched respectively to form a substrate with through holes and a support area and a diaphragm; wherein the substrate includes the first silicon layer with through holes and the silicon dioxide layer with through holes.

[0139] in, Fig. 20 FIG. 1 is a diagram of a transducer structure after the thinning layer provided by an embodiment of the present invention. Fig. 20 The base material layer 100 may be an SOI substrate. Thinning the back surface of the base material layer 100 may improve the accuracy of the subsequent etching process, thereby improving the process consistency of the device.

[0140] Fig.21 Schematic diagram of the first silicon layer and the silicon dioxide layer being etched away provided by an embodiment of the present invention. Figure 2 , Fig. 20 and Fig.21, the first silicon layer 101 is etched by deep reactive ion etching (Deep-RIE), and the silicon dioxide layer 103 is etched by inductively coupled plasma etching (Inductively Coupled Plasma Etcher, ICP) to release the device diaphragm 20.

[0141] Specifically, the stacked first silicon layer 101, silicon dioxide layer 103 and second silicon layer 102 are used as the base material layer 100. Among them, the second silicon layer 102 is arranged on the side of the silicon dioxide layer 103 adjacent to the bottom electrode layer 30. The first silicon layer 101 is thinned to reduce the overall thickness of the substrate while retaining sufficient mechanical strength to support the subsequent etching and diaphragm 20 formation process. The first silicon layer 101 and the silicon dioxide layer 103 are etched respectively. Through a precise etching process, a through hole 11 and a support area 12 are formed in the first silicon layer 101 and the silicon dioxide layer 103. The through hole 11 is used for subsequent electrode connection and signal transmission, while the support area 12 is used to support the diaphragm 20 and prevent it from collapsing, thereby improving the overall stability of the structure. The diaphragm 20 is a key component of the MEMS ultrasonic transducer, which is used to generate vibrations and emit ultrasonic waves under the action of an electric field.

[0142] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0143] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A MEMS ultrasonic transducer, characterized in that: include: A substrate, and a diaphragm, a bottom electrode layer, a piezoelectric layer and a top electrode layer stacked in sequence on one side of the substrate; the diaphragm is arranged on a side of the bottom electrode layer adjacent to the substrate; The substrate comprises a through hole and a support area surrounding the through hole; The vertical projection of the diaphragm on the substrate covers the through hole and at least a part of the supporting area; The bottom electrode layer comprises an inner bottom electrode and an outer bottom electrode, wherein a gap is provided between the inner bottom electrode and the outer bottom electrode, and the outer bottom electrode surrounds the inner bottom electrode; the vertical projection of the inner bottom electrode on the substrate is located in the through hole, and the vertical projection of the outer bottom electrode on the substrate covers part of the through hole and at least part of the support area; The piezoelectric layer comprises an inner piezoelectric layer and an outer piezoelectric layer, wherein a gap is provided between the inner piezoelectric layer and the outer piezoelectric layer, and the outer piezoelectric layer surrounds the inner piezoelectric layer; the vertical projection of the inner piezoelectric layer on the bottom electrode layer is located inside the inner bottom electrode, and the vertical projection of the outer piezoelectric layer on the substrate covers part of the through hole and at least part of the support area; The top electrode layer comprises an inner ring top electrode and an outer ring top electrode, wherein a gap is provided between the inner ring top electrode and the outer ring top electrode; the outer ring top electrode surrounds the inner ring top electrode, the vertical projection of the inner ring top electrode on the piezoelectric layer is located within the inner ring piezoelectric layer, and the vertical projection of the outer ring top electrode on the piezoelectric layer is located within the outer ring piezoelectric layer; The outer ring top electrode is electrically connected to the inner ring bottom electrode, and the outer ring bottom electrode is electrically connected to the inner ring top electrode.

2. The MEMS ultrasonic transducer according to claim 1, characterized in that: Also includes: An insulating layer, wherein the insulating layer covers the gap between the inner circle bottom electrode and the outer circle bottom electrode, and at least a portion of the gap between the inner circle piezoelectric layer and the outer circle piezoelectric layer.

3. The MEMS ultrasonic transducer according to claim 2, characterized in that: The outer ring top electrode also has an opening, and the opening penetrates the outer ring top electrode along the direction from the outer ring top electrode to the inner ring top electrode, and the insulating layer also covers the piezoelectric layer at the opening; A first signal line and a second signal line are arranged on a surface of the insulating layer at the opening away from the substrate; a first end of the first signal line is electrically connected to the inner circle bottom electrode through a first through hole in the insulating layer at the gap, or a portion of the inner circle bottom electrode is exposed between a first edge of the insulating layer at the gap adjacent to the inner circle piezoelectric layer and the inner circle piezoelectric layer, and a first end of the first signal line crosses the first edge and contacts and is electrically connected to the inner circle bottom electrode at the exposed portion; a second end of the first signal line is electrically connected to the outer circle top electrode; The first end of the second signal line is electrically connected to the inner ring top electrode, the second end of the second signal line is located on the side of the outer ring top electrode away from the inner ring top electrode, and the second end of the second signal line is electrically connected to the outer ring bottom electrode through a second through hole in the piezoelectric layer.

4. The MEMS ultrasonic transducer according to claim 3, characterized in that: Also includes: a first external pin and a second external pin; The first external pin and the second external pin are located on a side of the piezoelectric layer away from the substrate, and are located on a side of the outer ring top electrode away from the inner ring top electrode; The first signal line is electrically connected to the first external pin, and the second signal line is electrically connected to the second external pin.

5. The MEMS ultrasonic transducer according to claim 4, characterized in that: The first signal line, the second signal line, the first external pin and the second external pin are all located in the top electrode layer and are made of the same material as the top electrode layer.

6. The MEMS ultrasonic transducer according to claim 1, characterized in that: The substrate comprises a silicon substrate layer and a silicon dioxide layer, wherein the silicon dioxide layer is arranged on a side of the silicon substrate layer adjacent to the diaphragm.

7. A method for manufacturing a MEMS ultrasonic transducer, characterized in that: providing a base material layer; A bottom electrode layer, a piezoelectric layer and a top electrode layer are arranged on the surface of the base material layer; wherein the bottom electrode layer, the piezoelectric layer and the top electrode layer are stacked in sequence, and the piezoelectric layer is arranged on a side of the bottom electrode layer away from the base material layer; Patterning the surface of the base material layer away from the bottom electrode layer to form a base with through holes and a support area and a diaphragm; The supporting area surrounds the through hole, and the diaphragm is arranged on a side of the substrate adjacent to the bottom electrode layer; the vertical projection of the diaphragm on the substrate covers the through hole and at least a part of the supporting area; The bottom electrode layer comprises an inner bottom electrode and an outer bottom electrode, wherein a gap is provided between the inner bottom electrode and the outer bottom electrode, and the outer bottom electrode surrounds the inner bottom electrode; the vertical projection of the inner bottom electrode on the substrate is located in the through hole, and the vertical projection of the outer bottom electrode on the substrate covers part of the through hole and at least part of the support area; The piezoelectric layer comprises an inner piezoelectric layer and an outer piezoelectric layer, wherein a gap is provided between the inner piezoelectric layer and the outer piezoelectric layer, and the outer piezoelectric layer surrounds the inner piezoelectric layer; the vertical projection of the inner piezoelectric layer on the bottom electrode layer is located inside the inner bottom electrode, and the vertical projection of the outer piezoelectric layer on the substrate covers part of the through hole and at least part of the support area; The top electrode layer comprises an inner ring top electrode and an outer ring top electrode, wherein a gap is provided between the inner ring top electrode and the outer ring top electrode; the outer ring top electrode surrounds the inner ring top electrode, the vertical projection of the inner ring top electrode on the piezoelectric layer is located within the inner ring piezoelectric layer, and the vertical projection of the outer ring top electrode on the piezoelectric layer is located within the outer ring piezoelectric layer; The outer ring top electrode is electrically connected to the inner ring bottom electrode, and the outer ring bottom electrode is electrically connected to the inner ring top electrode.

8. The method according to claim 7, characterized in that: A bottom electrode layer, a piezoelectric layer and a top electrode layer are arranged on the surface of the base material layer, including: Disposing a bottom electrode material layer on the surface of the base material layer; Disposing a piezoelectric material layer on the surface of the bottom electrode material layer; Patterning the piezoelectric material layer to form the piezoelectric layer; Patterning the bottom electrode material layer to form the bottom electrode layer; An insulating layer is provided; wherein the insulating layer covers the gap between the inner circle bottom electrode and the outer circle bottom electrode, and at least a part of the gap between the inner circle piezoelectric layer and the outer circle piezoelectric layer; Disposing a top electrode material layer on the surface of the piezoelectric layer; The top electrode material layer is patterned to form the top electrode layer.

9. The manufacturing method according to claim 8, characterized in that: Patterning the top electrode material layer to form the top electrode layer includes: Etching the top electrode material layer to form an inner ring top electrode, an outer ring top electrode, a first signal line, a second signal line, a first external pin and a second external pin; Wherein, the outer ring top electrode has an opening, and the opening penetrates the outer ring top electrode along the direction from the outer ring top electrode to the inner ring top electrode, and the insulating layer also covers the piezoelectric layer at the opening; The first signal line and the second signal line are arranged on the surface of the insulating layer at the opening away from the substrate, the first end of the first signal line is electrically connected to the inner circle bottom electrode through the first through hole in the insulating layer at the gap, or, the insulating layer at the gap is adjacent to the first edge of the inner circle piezoelectric layer and a portion of the inner circle bottom electrode is exposed between the inner circle piezoelectric layer, and the first end of the first signal line crosses the first edge and contacts and is electrically connected to the inner circle bottom electrode at the exposed portion; the second end of the first signal line is electrically connected to the outer circle top electrode; The first end of the second signal line is electrically connected to the inner ring top electrode, the second end of the second signal line is located on a side of the outer ring top electrode away from the inner ring top electrode, and the second end of the second signal line is electrically connected to the outer ring bottom electrode through a second through hole in the piezoelectric layer; The first external pin and the second external pin are located on a side of the piezoelectric layer away from the substrate, and on a side of the outer ring top electrode away from the inner ring top electrode; the first signal line is electrically connected to the first external pin, and the second signal line is electrically connected to the second external pin.

10. The manufacturing method according to claim 7, characterized in that: The base material layer comprises a first silicon layer, a silicon dioxide layer and a second silicon layer which are stacked, wherein the second silicon layer is arranged on a side of the silicon dioxide layer adjacent to the bottom electrode layer; Patterning the surface of the base material layer away from the bottom electrode layer to form a base with through holes and a support area and a diaphragm includes: Thinning the first silicon layer; The first silicon layer and the silicon dioxide layer are etched respectively to form a substrate having a through hole and a support area and a diaphragm; wherein the substrate includes the first silicon layer having a through hole and the silicon dioxide layer having a through hole.

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