An ultrasonic transducer substrate, a manufacturing method and apparatus thereof

Abstract

The embodiment of the present disclosure discloses an ultrasonic transduction substrate and a manufacturing method and equipment thereof, the ultrasonic transmitting structure can transmit ultrasonic waves, and the ultrasonic receiving structure can receive ultrasonic waves. Compared with the integrated structure of transmitting and receiving in the related art, the structure of the present disclosure can be independently controlled by separating the transmitting and receiving structures. Thus, the material and structure of the ultrasonic transmitting structure and the ultrasonic receiving structure can be designed specifically, thereby facilitating the improvement of the working performance of the ultrasonic transmitting structure and the ultrasonic receiving structure. Furthermore, the ultrasonic receiving structure surrounds the ultrasonic transmitting structure, which can avoid the crosstalk of the reflected ultrasonic signals between the ultrasonic receiving structures, reduce the noise of the signals, improve the signal-to-noise ratio, and thus improve the imaging quality and clarity.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of ultrasonic detection, and particularly relates to an ultrasonic transduction substrate, a manufacturing method and device thereof. BACKGROUND

[0002] Micromachined Ultrasonic Transducer (MUT) is a kind of MEMS (Micro-Electro-Mechanical System) device that emits or receives ultrasonic signals by making piezoelectric film vibrate through electric effect. The micromachined ultrasonic transducer includes PMUT (Piezoelectric Micromachined Ultrasonic Transducer) and CMUT (Capacitance Micrmachined Ultrasonic Transducer).

[0003] The above two kinds of micromachined ultrasonic transducers can bring revolutionary changes to ultrasonic imaging technology. SUMMARY

[0004] The present disclosure provides an ultrasonic transduction substrate, a manufacturing method and device thereof, and the specific solutions are as follows:

[0005] The ultrasonic transduction substrate provided by the present disclosure includes a substrate and a plurality of ultrasonic transduction units arranged on the substrate, and the ultrasonic transduction unit includes:

[0006] An ultrasonic emission structure configured to convert a received electrical signal into an ultrasonic signal;

[0007] An ultrasonic receiving structure, a normal projection of which on the substrate surrounds a normal projection of the ultrasonic emission structure on the substrate, and the ultrasonic receiving structure is configured to output an electrical signal converted from a received ultrasonic signal;

[0008] A driving circuit arranged between the substrate and the ultrasonic receiving structure, and the driving circuit is electrically connected to the ultrasonic receiving structure, and the driving circuit is configured to receive the electrical signal output by the ultrasonic receiving structure.

[0009] In a possible implementation, in the ultrasonic transduction substrate provided by the present disclosure, the ultrasonic emission structure includes:

[0010] A cavity arranged close to the substrate;

[0011] a first passivation layer disposed on a side of the first passivation layer facing away from the substrate, a projection of the first passivation layer on the substrate covering a projection of the cavity on the substrate;

[0012] a first electrode disposed on a side of the first electrode facing away from the substrate, the first electrode configured to receive a driving voltage;

[0013] a first piezoelectric structure disposed on a side of the first piezoelectric structure facing away from the substrate;

[0014] a second electrode disposed on a side of the second electrode facing away from the substrate, the second electrode grounded.

[0015] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, the ultrasonic transmitting structure further comprises an etching hole in communication with the cavity, and a projection of the first passivation layer on the substrate does not overlap with a projection of the etching hole on the substrate.

[0016] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, a shape of a projection of the first passivation layer on the substrate is the same as a shape of a projection of the cavity on the substrate.

[0017] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, a ratio of a size of the first passivation layer to a size of the cavity is greater than or equal to 1.2 and less than or equal to 1.5.

[0018] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, a plurality of the ultrasonic transducing units are arranged in an array on the substrate; wherein,

[0019] Each of the etching holes corresponding to each of the cavities is independently disposed, or each of the etching holes corresponding to cavities in a same column is in communication with each other.

[0020] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, a shape of a projection of the first electrode on the substrate comprises a circle or a square.

[0021] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, the ultrasonic receiving structure comprises:

[0022] a third electrode, disposed apart from the first electrode, the third electrode being located on the same side of the cavity as the first electrode, and a footprint of the third electrode on the substrate substrate surrounding a footprint of the first electrode on the substrate substrate, the third electrode being electrically connected with the driving circuit;

[0023] a second piezoelectric structure, disposed on a side of the third electrode away from the substrate substrate;

[0024] a fourth electrode, disposed on a side of the second piezoelectric structure away from the substrate substrate, the fourth electrode being grounded.

[0025] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, the first electrode and the third electrode are disposed in the same layer.

[0026] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, the first electrode and the third electrode are disposed in different layers, and a second passivation layer is disposed between the first electrode and the third electrode.

[0027] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, the first electrode is disposed close to the substrate substrate, or the third electrode is disposed close to the substrate substrate.

[0028] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, the second electrode and the fourth electrode are an integral structure disposed in an entirety, and the first piezoelectric structure and the second piezoelectric structure are an integral structure disposed in an entirety.

[0029] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, the second electrode and the fourth electrode are disposed apart, and a footprint of the fourth electrode on the substrate substrate surrounds a footprint of the second electrode on the substrate substrate;

[0030] The first piezoelectric structure and the second piezoelectric structure are disposed apart, and a footprint of the second piezoelectric structure on the substrate substrate surrounds a footprint of the first piezoelectric structure on the substrate substrate.

[0031] In a possible implementation, in the above ultrasonic transducing substrate provided by the embodiments of the present disclosure, further comprising: a third passivation layer disposed in an entirety between the first electrode and / or the third electrode and the first piezoelectric structure, and an organic layer disposed in an entirety between the first electrode and / or the third electrode and the first passivation layer.

[0032] In a possible implementation, in the ultrasonic transduction substrate provided in the embodiments of the present disclosure, a first overlap electrode is further included and arranged in the same layer as the cavity and spaced apart, the third electrode is electrically connected to the first overlap electrode, and the first overlap electrode is electrically connected to the driving circuit.

[0033] The cavity and the first overlap electrode are peripherally filled with a resin layer.

[0034] In a possible implementation, in the ultrasonic transduction substrate provided in the embodiments of the present disclosure, the material of the first piezoelectric structure and the material of the second piezoelectric structure include polyvinylidene fluoride.

[0035] Correspondingly, the embodiments of the present disclosure further provide a device including the ultrasonic transduction substrate provided in the embodiments of the present disclosure.

[0036] Correspondingly, the embodiments of the present disclosure further provide a manufacturing method of an ultrasonic transduction substrate, used for manufacturing the ultrasonic transduction substrate provided in the embodiments of the present disclosure, and the manufacturing method includes the following steps.

[0037] A substrate is provided.

[0038] A plurality of ultrasonic transduction units are formed on one side of the substrate.

[0039] The ultrasonic transduction units are formed by the following steps.

[0040] A driving circuit is formed on one side of the substrate.

[0041] An ultrasonic transmitting structure and an ultrasonic receiving structure are formed on the side of the driving circuit away from the substrate, the driving circuit is electrically connected to the ultrasonic receiving structure, and the orthographic projection of the ultrasonic receiving structure on the substrate surrounds the orthographic projection of the ultrasonic transmitting structure on the substrate; wherein the ultrasonic transmitting structure is configured to convert a received electrical signal into an ultrasonic signal, the ultrasonic receiving structure is configured to output an electrical signal converted from a received ultrasonic signal, and the driving circuit is configured to receive the electrical signal output by the ultrasonic receiving structure.

[0042] In a possible implementation, in the manufacturing method provided in the embodiments of the present disclosure, the ultrasonic transmitting structure includes a cavity, a first passivation layer, a first electrode, a first piezoelectric structure, and a second electrode arranged in sequence; wherein the cavity is formed by the following steps.

[0043] A metal thin film is formed on the side away from the substrate, the metal thin film includes a cavity region, a non-cavity region, and an etching hole region, and the etching hole region is in communication with the cavity region.

[0044] etching the non-cavity region to remove the metal in the non-cavity region;

[0045] filling a resin layer in the non-cavity region where the metal is removed;

[0046] forming the first passivation layer on the side of the cavity region away from the substrate, etching the first passivation layer so that the orthogonal projection of the first passivation layer on the substrate covers the orthogonal projection of the cavity region on the substrate, and the orthogonal projection of the first passivation layer on the substrate does not overlap with the orthogonal projection of the etching hole region on the substrate;

[0047] injecting etching liquid into the etching hole region, etching the cavity region to remove the metal in the cavity region, and forming the cavity. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 A structural schematic diagram of an ultrasonic transduction substrate provided by an embodiment of the present disclosure;

[0049] Figure 2 Another structural schematic diagram of an ultrasonic transduction substrate provided by an embodiment of the present disclosure;

[0050] Figure 3 Another structural schematic diagram of an ultrasonic transduction substrate provided by an embodiment of the present disclosure;

[0051] Figure 4 Another structural schematic diagram of an ultrasonic transduction substrate provided by an embodiment of the present disclosure;

[0052] Figure 5 Another structural schematic diagram of an ultrasonic transduction substrate provided by an embodiment of the present disclosure;

[0053] Figure 6 Another structural schematic diagram of an ultrasonic transduction substrate provided by an embodiment of the present disclosure;

[0054] Figure 7 A planar schematic diagram of a first electrode and a third electrode;

[0055] Figure 8 Another planar schematic diagram of a first electrode and a third electrode;

[0056] Figure 9 A planar schematic diagram of a cavity in a plurality of ultrasonic transduction units;

[0057] Figure 10 Another planar schematic diagram of a cavity in a plurality of ultrasonic transduction units;

[0058] Figure 11 An ultrasonic imaging principle schematic diagram of an ultrasonic transduction substrate provided by an embodiment of the present disclosure;

[0059] Figure 12 A flowchart of a method for manufacturing an ultrasonic transduction substrate according to an embodiment of the present disclosure is shown in FIG. 1.

[0060] Figure 13 A flowchart of a method for manufacturing an ultrasonic transduction substrate according to an embodiment of the present disclosure is shown in FIG. 2.

[0061] Figures 14A-14I The structure of the ultrasonic transduction substrate after each step is performed is shown in FIGS. 3 and 4. DETAILED DESCRIPTION

[0062] In order to make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of, but not all of the embodiments of the present disclosure. And the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict, if necessary. Based on the described embodiments of the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present disclosure.

[0063] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood as the general meaning understood by a person with ordinary skill in the art to which the present disclosure belongs. The similar words such as “comprise” or “include” and the like used in the present disclosure mean that the elements or objects before the words cover the elements or objects listed after the words and their equivalents, and other elements or objects are not excluded. The similar words such as “connect” or “connected” are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect. “In”, “out”, “up”, “down”, and the like are only used to indicate relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0064] It should be noted that the size and shape of each figure in the drawings do not reflect the true proportions, but only serve to illustrate the present disclosure. And the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout the drawings.

[0065] In the related art, three mainstream micro-mechanical ultrasonic transduction device structures include PMUT, CMUT and sandwich structure ultrasonic imaging devices.

[0066] The ultrasonic imaging principle of CMUT utilizes the difference in capacitance between upper and lower electrodes with a certain interval, causing the diaphragm located between them to generate sound by electrostatic attraction. The interval between the upper and lower electrodes needs to be designed, and it cannot be too large, otherwise the electrostatic attraction will not be strong. For micro-mechanical devices, this is difficult to fabricate.

[0067] The ultrasonic imaging principle of PMUT and sandwich structures utilizes the direct and inverse piezoelectric effects of piezoelectric materials. When a certain voltage is applied to a piezoelectric material, it deforms and vibrates, generating ultrasonic waves; this phenomenon is the inverse piezoelectric effect. When a certain force (ultrasonic waves) is applied to a piezoelectric material, it deforms and generates charges on its surface, converting the ultrasonic waves into electrical signals; this phenomenon is the direct piezoelectric effect. However, in sandwich structures, the vibration mode of the piezoelectric layer is along the thickness direction (i.e., without cavities). To increase the intensity of the ultrasonic signal, the excitation voltage is generally increased when emitting the ultrasonic signal. However, increasing the excitation voltage increases power consumption, and the piezoelectric layer is easily broken down, losing its piezoelectric properties.

[0068] However, most ultrasound imaging devices in related technologies are designed as transceivers and basically adopt a sandwich structure. This type of device structure not only has low signal transmission intensity and weak signal intensity after reflection, but also easily causes crosstalk between the reflected ultrasonic signals, increasing noise, reducing the signal-to-noise ratio, and ultimately affecting the imaging quality.

[0069] In view of this, embodiments of this disclosure provide an ultrasonic transducer substrate, such as... Figures 1-6 As shown, the device includes a substrate 1 and a plurality of ultrasonic transducer units P disposed on the substrate 1. The ultrasonic transducer unit P includes:

[0070] The ultrasonic transmitting structure 2 is configured to convert the received electrical signal into an ultrasonic signal;

[0071] An ultrasonic receiving structure 3 is provided, with its orthogonal projection on the substrate 1 surrounding the orthogonal projection of the ultrasonic transmitting structure 2 on the substrate 1. The ultrasonic receiving structure 3 is configured to convert the received ultrasonic signal into an electrical signal and then output it.

[0072] The driving circuit 4 is disposed between the substrate 1 and the ultrasonic receiving structure 3, and the driving circuit 1 is electrically connected to the ultrasonic receiving structure 3. The driving circuit 4 is configured to receive the electrical signal output by the ultrasonic receiving structure 3.

[0073] Compared with the structure integrating the emitting and receiving in the related art, the structure separating the emitting and receiving provided by the present disclosure can be independently controlled, so that the material and structure of the ultrasonic emitting structure and the ultrasonic receiving structure can be designed specifically, thereby facilitating the improvement of the working performance of the ultrasonic emitting structure and the ultrasonic receiving structure; and the ultrasonic receiving structure surrounds the ultrasonic emitting structure, so that the reflected ultrasonic signals can be prevented from causing crosstalk between the ultrasonic receiving structures, the noise of the signals is reduced, the signal-to-noise ratio is improved, and the imaging quality and the definition are improved.

[0074] Optionally, the substrate 1 can be a flexible substrate, such as a flexible material substrate of polyimide, and can also be a rigid substrate of glass, quartz or silicon.

[0075] Specifically, as shown in Figures 1-6 The driving circuit 4 includes a thin film transistor, which includes an active layer Act arranged between the substrate 1 and the ultrasonic receiving structure 3, a gate G arranged between the active layer Act and the ultrasonic receiving structure 3, and a source S and a drain D arranged between the gate G and the ultrasonic receiving structure 3. The ultrasonic transduction substrate further includes a first lap joint electrode 5 arranged between the source S, the drain D and the ultrasonic receiving structure 3, and a second lap joint electrode 6 arranged between the first lap joint electrode 5 and the source S and the drain D; one side of the second lap joint electrode 6 is electrically connected to the source S or the drain D of the thin film transistor (the present disclosure takes the example that the second lap joint electrode 6 is electrically connected to the source S), the other side of the second lap joint electrode 6 is electrically connected to one side of the first lap joint electrode 5, and the other side of the first lap joint electrode 5 is electrically connected to the ultrasonic receiving structure 3.

[0076] Specifically, as shown in Figures 1-6 The ultrasonic transduction substrate further includes a buffer layer 7 arranged between the substrate 1 and the active layer Act, a barrier layer 8 arranged between the buffer layer 7 and the active layer Act, a gate insulating layer 9 arranged between the active layer Act and the gate G, an interlayer insulating layer 10 arranged between the gate G and the source S and the drain D, a planar layer 11 arranged between the source S, the drain D and the second lap joint electrode 6, and a fourth passivation layer 12 arranged between the first lap joint electrode 5 and the second lap joint electrode 6; wherein the source S and the drain D are electrically connected to the active layer Act through a via hole penetrating the interlayer insulating layer 10 and the gate insulating layer 9, the second lap joint electrode 6 is electrically connected to the source S through a via hole penetrating the planar layer 11, and the first lap joint electrode 5 is electrically connected to the second lap joint electrode 6 through a via hole penetrating the fourth passivation layer 12.

[0077] Optionally, the first lap joint electrode 5 and the second lap joint electrode 6 can be metal electrodes.

[0078] Specifically, as shown in Figures 1-6 each drive circuit 4 in the embodiment of the present disclosure is only drawn with one thin film transistor, in a specific device structure, the circuit structure of the drive circuit 4 corresponding to the ultrasonic receiving structure 3 can be a 3T1C structure or a 4T1C structure, and the thin film transistor can be an LTPS structure or an LTPO structure.

[0079] In specific implementation, in the above ultrasonic transduction substrate provided by the embodiment of the present disclosure, as shown in Figures 1-6 the ultrasonic transmitting structure 2 can include:

[0080] a cavity 21 arranged close to the substrate substrate 1;

[0081] a first passivation layer 22 arranged on the side of the cavity 21 away from the substrate substrate 1, and the orthographic projection of the first passivation layer 22 on the substrate substrate 1 covers the orthographic projection of the cavity 21 on the substrate substrate 1;

[0082] a first electrode 23 arranged on the side of the first passivation layer 22 away from the substrate substrate 1, and the first electrode 23 is configured to receive a driving voltage;

[0083] a first piezoelectric structure 24 arranged on the side of the first electrode 23 away from the substrate substrate 1;

[0084] a second electrode 25 arranged on the side of the first piezoelectric structure 24 away from the substrate substrate 1, and the second electrode 25 is grounded.

[0085] In specific implementation, in the above ultrasonic transduction substrate provided by the embodiment of the present disclosure, as shown in Figures 1-6 the first bonding electrode 5 can be arranged in the same layer as the cavity 21 and spaced apart, and the periphery of the cavity 21 and the first bonding electrode 5 can be filled with a resin layer 13.

[0086] In specific implementation, in the above ultrasonic transduction substrate provided by the embodiment of the present disclosure, as shown in Figures 1-6 the ultrasonic receiving structure 3 can include:

[0087] a third electrode 31 arranged spaced apart from the first electrode 23, the third electrode 31 and the first electrode 23 are located on the same side of the cavity 21, and the orthographic projection of the third electrode 31 on the substrate substrate 1 surrounds the orthographic projection of the first electrode 23 on the substrate substrate 1, and the third electrode 31 is electrically connected with the drive circuit 4; specifically, the third electrode 31 is electrically connected with the first bonding electrode 5, that is, the third electrode 31 is electrically connected with the source S of the thin film transistor in the drive circuit 4 through the first bonding electrode 5 and the second bonding electrode 6;

[0088] a second piezoelectric structure 32 arranged on the side of the third electrode 31 away from the substrate substrate 1;

[0089] A fourth electrode 33 is disposed on the side of the second piezoelectric structure 32 away from the substrate 1, and the fourth electrode 33 is grounded.

[0090] Specifically, as shown in FIG. 1, the ultrasonic transmitting structure 2 is a PMUT structure, and the ultrasonic receiving structure 3 is a sandwich structure. Such a device structure not only can enhance the transmission intensity of the ultrasonic signal and improve the imaging quality, but also can separate the ICs for transmission and reception and control them separately. Figures 1-6

[0091] In a specific implementation, in the ultrasonic transducing substrate provided in the embodiments of the present disclosure, as shown in FIG. 1, Figure 7 Figure 7 is a plan view of the first electrode 23 and the third electrode 31. The first electrode 23 has a circular shape in the orthographic projection on the substrate 1, and the third electrode 31 has a circular ring shape in the orthographic projection on the substrate 1. As shown in FIG. 2, Figure 8 Figure 8 is another plan view of the first electrode 23 and the third electrode 31. The first electrode 23 has a square shape in the orthographic projection on the substrate 1, and the third electrode 31 has a square ring shape in the orthographic projection on the substrate 1. The concentric ring design of the first electrode 23 and the third electrode 31 can avoid the occurrence of the crosstalk phenomenon of the reflected ultrasonic signal between different ultrasonic receiving structures 3, reduce the signal noise, and thus improve the imaging quality.

[0092] Optionally, the material of each electrode can be a metal material with conductive properties, such as gold, molybdenum, nickel, etc., which can be formed by using the sputtering, electroplating, and other processes in the prior art.

[0093] Specifically, as shown in FIG. 1, the first electrode 23 and the second electrode 25 are used to provide an electrical signal to the first piezoelectric structure 24. The first piezoelectric structure 24 deforms (inverse piezoelectric effect) under the action of the electrical signal, and the cavity 21 provides vibration when the first piezoelectric structure 24 deforms, thereby generating ultrasonic waves. Thus, the ultrasonic transmitting structure 2 realizes the generation of ultrasonic signal transmission according to the electrical signal. The second piezoelectric structure 32 deforms when receiving the ultrasonic signal, and then the third electrode 31 has a charge (positive piezoelectric effect), thereby generating an electrical signal to the driving circuit 4. Thus, the ultrasonic receiving structure 3 realizes the generation of an electrical signal according to the received ultrasonic signal. Figures 1-6

[0094] Specifically, as shown in FIG. 1, the first electrode 23 and the second electrode 25 are used to provide an electrical signal to the first piezoelectric structure 24. The first piezoelectric structure 24 deforms (inverse piezoelectric effect) under the action of the electrical signal, and the cavity 21 provides vibration when the first piezoelectric structure 24 deforms, thereby generating ultrasonic waves. Thus, the ultrasonic transmitting structure 2 realizes the generation of ultrasonic signal transmission according to the electrical signal. The second piezoelectric structure 32 deforms when receiving the ultrasonic signal, and then the third electrode 31 has a charge (positive piezoelectric effect), thereby generating an electrical signal to the driving circuit 4. Thus, the ultrasonic receiving structure 3 realizes the generation of an electrical signal according to the received ultrasonic signal. Figures 1-6 ​​​​As shown, the ultrasonic emission structure 2 provided by the embodiment of the present disclosure sets the cavity 21, so that the vibration mode of the first piezoelectric structure 24 is a cantilever beam vibration mode, the vibration amplitude of the cantilever beam is larger, and the ultrasonic signal strength generated is stronger. Compared with the vibration mode of the sandwich structure along the thickness direction of the piezoelectric layer in the related art, the cantilever beam vibration can further improve the ultrasonic signal strength.

[0095] Optionally, the materials of the first piezoelectric structure 24 and the second piezoelectric structure 32 can be the same or different. Optionally, the materials of the first piezoelectric structure 24 and the second piezoelectric structure 32 can include polyvinylidene fluoride (PVDF). Further, in the case where the materials of the first piezoelectric structure 24 and the second piezoelectric structure 32 are the same, both can be organic P(VDF-TrFE) binary copolymer. In the case where the materials of the first piezoelectric structure 24 and the second piezoelectric structure 32 are different, since the ultrasonic emission structure 2 needs to emit ultrasonic waves, the first piezoelectric structure 24 thereof can adopt a material with strong electro-acoustic conversion capability, such as organic P(VDF-TrFE-CTE) ternary copolymer; since the ultrasonic receiving structure 3 needs to emit ultrasonic waves, the second piezoelectric structure 32 thereof can adopt a material with strong acoustic-electric conversion capability, such as organic P(VDF-TrFE) binary copolymer. Therefore, the performance of the ultrasonic transduction substrate can be enhanced.

[0096] In specific implementation, in the above ultrasonic transduction substrate provided by the embodiment of the present disclosure, as shown in Figures 1-6 As shown, the ultrasonic emission structure 2 further includes an etching hole (not shown) in communication with the cavity 21, and the orthographic projection of the first passivation layer 22 on the substrate 1 does not overlap with the orthographic projection of the etching hole on the substrate 1. Specifically, the cavity 21 can be made by etching the metal sacrificial layer, first etching the metal in the non-cavity part, then filling and leveling with an organic material (such as resin), forming the first passivation layer 22, etching the first passivation layer 22 to form an opening corresponding to the etching hole, and then etching the metal in the cavity part through the etching hole to form the cavity 21.

[0097] The ultrasonic transduction substrate provided by the embodiment of the present disclosure adopts organic PVDF material for the piezoelectric structure and adopts the method of etching the metal sacrificial layer for the cavity, so that the integrated preparation of the ultrasonic emission structure, the ultrasonic receiving structure and the thin film transistor can be realized.

[0098] In specific implementation, in the above ultrasonic transduction substrate provided by the embodiment of the present disclosure, as shown in Figure 9 and Figure 10 As shown, Figure 9 and Figure 10This is a planar schematic diagram of cavities 21 within multiple ultrasonic transducer units P. The multiple ultrasonic transducer units P are arranged in an array on the substrate 1, meaning that the multiple cavities 21 are arranged in an array on the substrate 1; wherein,

[0099] like Figure 9 As shown, each etched hole V corresponding to each cavity 21 is set independently, that is, each cavity 21 is provided with one etched hole V, and the cavities 21 are not related to each other; or, as Figure 10 As shown, the etched holes V corresponding to the cavities 21 in the same column are interconnected. That is, an etch channel H can be set on the same column to connect the etched holes V in that column.

[0100] In specific implementation, in the ultrasonic transducer substrate provided in the embodiments of this disclosure, such as Figures 1-6 As shown, the orthographic projection shape of the first passivation layer 22 on the substrate 1 is the same as the orthographic projection shape of the cavity 21 on the substrate 1. Of course, they can also be different.

[0101] In specific implementation, in the ultrasonic transducer substrate provided in the embodiments of this disclosure, the first passivation layer 22 in each ultrasonic emitting structure 2 can be an integral structure, and the first passivation layer 22 of the integral structure only needs to expose the etched holes.

[0102] In specific implementation, in the ultrasonic transducer substrate provided in the embodiments of this disclosure, such as Figures 1-6 As shown, the first passivation layer 22 in each ultrasonic emitting structure 2 can be an independent structure. For example, the ratio of the size of the first passivation layer 22 to the size of the cavity 21 is greater than or equal to 1.2 and less than or equal to 1.5. In this way, the boundary of the first passivation layer 22 can overlap the resin layer 13 surrounding the cavity 21, avoiding the collapse of the piezoelectric structure and electrodes above.

[0103] Optionally, the cavity 21 can be a circular cavity, and the first passivation layer 22 can be a circular passivation layer. In this case, the ratio of the radius of the orthogonal projection of the passivation layer 22 onto the substrate 1 to the radius of the orthogonal projection of the cavity 21 onto the substrate 1 is greater than or equal to 1.2 and less than or equal to 1.5. For example, the size ratio can be 1.2, 1.3, 1.4, or 1.5.

[0104] Optionally, the cavity 21 can be a rectangular cavity, and the first passivation layer 22 can be a rectangular passivation layer. In this case, the ratio of the diagonal of the orthographic projection of the first passivation layer 22 onto the substrate 1 to the diagonal of the orthographic projection of the cavity 21 onto the substrate 1 is greater than or equal to 1.2 and less than or equal to 1.5. For example, the size ratio can be 1.2, 1.3, 1.4, or 1.5.

[0105] In specific implementation, in the ultrasonic transducer substrate provided in the embodiments of this disclosure, such as Figure 1As shown, the first electrode 23 and the third electrode 31 are arranged in the same layer. In this way, only the original pattern needs to be changed when forming the first electrode 23, and the pattern of the third electrode 31 and the first electrode 23 can be formed in one patterning process. There is no need to add a separate process for preparing the third electrode 31, which can simplify the preparation process, save production costs, and improve production efficiency.

[0106] In specific implementation, in the ultrasonic transducer substrate provided in the embodiments of this disclosure, such as Figure 2 and Figure 3 As shown, the first electrode 23 and the third electrode 31 can be disposed in different layers, with a second passivation layer 14 disposed between them. This arrangement of the first electrode 23 and the third electrode 31 in different layers can prevent the formation of coupling capacitance between them when they are disposed in the same layer, which would lead to increased noise, ultimately reducing the signal-to-noise ratio and affecting the imaging quality.

[0107] Optionally, such as Figure 2 As shown, the first electrode 23 is disposed close to the substrate 1; Figure 3 As shown, the third electrode 31 is disposed close to the substrate 1.

[0108] In specific implementation, in the ultrasonic transducer substrate provided in the embodiments of this disclosure, such as Figures 1-3 As shown, the second electrode 25 and the fourth electrode 33 can be an integral structure formed over the entire surface, and the first piezoelectric structure 24 and the second piezoelectric structure 32 can also be an integral structure formed over the entire surface. In this way, the first electrode 23 and the third electrode 31 share the ground electrode formed over the entire surface (the integral structure of the second electrode 25 and the fourth electrode 33), and the ultrasonic transmitting structure 2 and the ultrasonic receiving structure 3 share a single piezoelectric layer, which simplifies the manufacturing process.

[0109] In specific implementation, in the ultrasonic transducer substrate provided in the embodiments of this disclosure, such as Figures 4-6 As shown, the second electrode 25 and the fourth electrode 33 can also be arranged at intervals, and the orthogonal projection of the fourth electrode 33 on the substrate 1 surrounds the orthogonal projection of the second electrode 25 on the substrate 1.

[0110] The first piezoelectric structure 24 and the second piezoelectric structure 32 can also be arranged alternately, with the orthographic projection of the second piezoelectric structure 32 on the substrate 1 surrounding the orthographic projection of the first piezoelectric structure 24 on the substrate 1. This patterning of the piezoelectric structures and grounding electrodes of the ultrasonic transmitting structure 2 and the ultrasonic receiving structure 3, corresponding to the first electrode 23 and the third electrode 31 respectively, ensures that the piezoelectric structures of the ultrasonic transmitting structure 2 and the ultrasonic receiving structure 3 do not interfere with each other, resulting in lower noise in the received signal of the ultrasonic receiving structure 3 and improved imaging quality.

[0111] It should be noted that,Figure 4 are spaced apart on the basis of Figure 1 , and the first piezoelectric structure 24 and the second piezoelectric structure 32 are spaced apart; Figure 5 are spaced apart on the basis of Figure 2 , and the first piezoelectric structure 24 and the second piezoelectric structure 32 are spaced apart; Figure 6 are spaced apart on the basis of Figure 3 , and the first piezoelectric structure 24 and the second piezoelectric structure 32 are spaced apart.

[0112] In the specific implementation, in the above ultrasonic transduction substrate provided by the embodiments of the present disclosure, as shown in Figure 1 and Figure 4 , further comprising: a third passivation layer 15 arranged between the first electrode 23 and the third electrode 31 and the first piezoelectric structure 24, and an organic layer 16 arranged between the first electrode 23 and the third electrode 31 and the first passivation layer 22. Specifically, the third passivation layer 15 can protect the first electrode 23 and the third electrode 31 from erosion when the first piezoelectric structure 24 is made, and the material of the organic layer 16 can be PI, so that the first piezoelectric structure 24 can drive the first passivation layer 22 and the organic layer 16 to vibrate together when vibrating.

[0113] In the specific implementation, in the above ultrasonic transduction substrate provided by the embodiments of the present disclosure, as shown in Figure 2 and Figure 5 , further comprising: a third passivation layer 15 arranged between the third electrode 31 and the first piezoelectric structure 24, and an organic layer 16 arranged between the first electrode 23 and the first passivation layer 22. Specifically, the third passivation layer 15 can protect the third electrode 31 from erosion when the first piezoelectric structure 24 is made, and the material of the organic layer 16 can be PI, so that the first piezoelectric structure 24 can drive the first passivation layer 22 and the organic layer 16 to vibrate together when vibrating.

[0114] In the specific implementation, in the above ultrasonic transduction substrate provided by the embodiments of the present disclosure, as shown in Figure 3 and Figure 6 , further comprising: a third passivation layer 15 arranged between the first electrode 23 and the first piezoelectric structure 24, and an organic layer 16 arranged between the third electrode 31 and the first passivation layer 22. Specifically, the third passivation layer 15 can protect the first electrode 23 from erosion when the first piezoelectric structure 24 is made, and the material of the organic layer 16 can be PI, so that the first piezoelectric structure 24 can drive the first passivation layer 22 and the organic layer 16 to vibrate together when vibrating.

[0115] Optionally, the materials of the first passivation layer 22, the second passivation layer 14, the third passivation layer 15, and the fourth passivation layer 12 can all be silicon nitride, silicon oxide, silicon oxynitride, etc.

[0116] Specifically, such as Figure 11 As shown, Figure 11 For Figure 1 The ultrasonic imaging principle of the ultrasonic transducer substrate provided in this embodiment is explained using the structure shown as an example: In the emission stage, a certain driving voltage is applied to the first electrode 23 to form a potential difference with the second electrode 25, driving the first piezoelectric structure 24 to vibrate and emit ultrasonic signals. After the ultrasonic signals are reflected by the target object 100 (e.g., the valleys and ridges of a finger), in the receiving stage, the ultrasonic signals return to the second piezoelectric structure 32 and convert the vibration signal into an electrical signal. This electrical signal is detected by the third electrode 31 and the fourth electrode 33 and transmitted to the driving circuit 4 to form a current that is read. Finally, it is processed by an external IC to form an image.

[0117] Optionally, the ultrasonic transducer substrate provided in this embodiment can be applied to portable electronic devices such as mobile phones for fingerprint detection, and can also be applied to medical ultrasound testing equipment for medical testing, such as B-ultrasound and color imaging.

[0118] Based on the same inventive concept, this disclosure also provides a method for fabricating an ultrasonic transducer substrate, used to fabricate the ultrasonic transducer substrate provided in this disclosure embodiment, such as... Figure 12 As shown, the manufacturing method includes:

[0119] S1201, Provides a substrate;

[0120] S1202, Multiple ultrasonic transducer units are formed on one side of the substrate;

[0121] like Figure 13 As shown, the ultrasonic transducer unit comprises:

[0122] S1301, A driving circuit is formed on one side of the substrate.

[0123] S1302. An ultrasonic transmitting structure and an ultrasonic receiving structure are formed on the side of the driving circuit away from the substrate. The driving circuit is electrically connected to the ultrasonic receiving structure. The orthographic projection of the ultrasonic receiving structure on the substrate surrounds the orthographic projection of the ultrasonic transmitting structure on the substrate. The ultrasonic transmitting structure is configured to convert the received electrical signal into an ultrasonic signal, the ultrasonic receiving structure is configured to convert the received ultrasonic signal into an electrical signal and output it, and the driving circuit is configured to receive the electrical signal output by the ultrasonic receiving structure.

[0124] The method for fabricating the ultrasonic transducer substrate provided in this disclosure, by fabricating independent ultrasonic transmitting and receiving structures, allows for targeted design of the materials and structures of the ultrasonic transmitting and receiving structures, compared to the integrated transmitting and receiving structures in related technologies. This facilitates improved performance of the ultrasonic transmitting and receiving structures. Furthermore, the ultrasonic receiving structure fabricated in this disclosure surrounds the ultrasonic transmitting structure, thus preventing crosstalk between the ultrasonic receiving structures caused by reflected ultrasonic signals, reducing signal noise, improving the signal-to-noise ratio, and thereby enhancing imaging quality and clarity.

[0125] The following is based on Figure 1 Taking the structure shown as an example, the method for fabricating the ultrasonic transducer substrate provided in this embodiment will be described, specifically including the following steps:

[0126] (1) As Figure 14A As shown, a buffer layer 7 is formed on a substrate 1. A barrier layer 8 is formed on the side of the buffer layer 7 away from the substrate 1. An active layer Act is formed on the side of the barrier layer 8 away from the substrate 1. A gate insulating layer 9 is formed on the side of the active layer Act away from the substrate 1. The gate insulating layer 9 has vias corresponding to the drain D and the source S, respectively. A gate G is formed on the side of the gate insulating layer 9 away from the substrate 1. An interlayer insulating layer 10 is formed on the side of the gate G away from the substrate 1. The interlayer insulating layer 10 has vias corresponding to the drain D and the source S, respectively. A drain D and a source S are formed on the side of the interlayer insulating layer 10 away from the substrate 1. The drain D and the source S are electrically connected to the active layer Act through the vias on the gate insulating layer 9 and the interlayer insulating layer 10, respectively.

[0127] (2) Figure 14B As shown, a planarization layer 11 is formed on the side of the drain D and source S away from the substrate 1. The planarization layer 11 has a via at the position corresponding to the source S. A second lap electrode 6 is formed on the side of the planarization layer 11 away from the substrate 1. A fourth passivation layer 12 is formed on the side of the second lap electrode 6 away from the substrate 1. The fourth passivation layer 12 has a via at the position corresponding to the second lap electrode 6.

[0128] (3) Figure 14C As shown, a metal thin film 21' is formed on the side of the fourth passivation layer 12 away from the substrate 1. The metal thin film 21' includes a cavity region, a non-cavity region, and an etched hole region. The etched hole region is connected to the cavity region. The non-cavity region is etched to remove the metal in the non-cavity region to retain the metal in the cavity region and the etched hole region. The metal in the first electrode overlap 5 region corresponding to the second overlap electrode 6 is also retained.

[0129] (4) Figure 14DAs shown, a resin layer 13 is filled in the non-cavity area where the metal has been removed.

[0130] (5) Figure 14E As shown, a first passivation layer 22 is formed on the side of the cavity region away from the substrate 1. The first passivation layer 22 is etched so that the orthogonal projection of the first passivation layer 22 on the substrate 1 covers the orthogonal projection of the cavity region on the substrate 1, and the orthogonal projection of the first passivation layer 22 on the substrate 1 does not overlap with the orthogonal projection of the etched hole region on the substrate 1.

[0131] (6) Figure 14F As shown, etching solution is injected into the etched hole area to etch the cavity area to remove the metal in the cavity area, forming cavity 21, and forming the first lap electrode 5 located on the same layer as cavity 21.

[0132] (7) Figure 14G As shown, an organic layer 16 is formed on the side of the first passivation layer 22 away from the substrate 1, and the organic layer 16 has a via at the position corresponding to the first lap electrode 5.

[0133] (8) Figure 14H As shown, a first electrode 23 and a third electrode 31 are formed on the side of the organic layer 16 away from the substrate 1, and are arranged in the same layer and are concentric rings. The first electrode 23 corresponds to the cavity 21.

[0134] (9) such as Figure 14I As shown, a third passivation layer 15 is formed on the side of the first electrode 23 and the third electrode 31 away from the substrate 1. A first piezoelectric structure 24 and a second piezoelectric structure 32 are formed on the side of the third passivation layer 15 away from the substrate 1 and are disposed on the entire surface. A second electrode 25 and a fourth electrode 33 are formed on the side of the first piezoelectric structure 24 away from the substrate 1 and are disposed on the entire surface.

[0135] Therefore, the embodiments of this disclosure are formed through the steps (1)-(9). Figure 1 The ultrasonic transducer substrate shown.

[0136] It should be noted that, Figures 2-6 The fabrication method of the ultrasonic transducer substrate shown is the same as Figure 1 The manufacturing methods shown are basically the same, the difference being that: the first electrode 23 and the third electrode 31 are set in different layers, the first piezoelectric structure 24 and the second piezoelectric structure 32 are independent structures, and the second electrode 25 and the fourth electrode 33 are independent structures.

[0137] Based on the same inventive concept, this disclosure also provides a device including the ultrasonic transducer substrate provided in the above-described embodiments of this disclosure.

[0138] Optionally, the device can be a display device, i.e., the display device can include the ultrasonic transduction substrate in any of the above embodiments, which can be configured into a fingerprint detection area of the display device, thereby realizing functions such as fingerprint unlocking on the display device. Since the ridges and valleys on the surface of the finger have different reflection intensities of ultrasonic signals, the ultrasonic energy reflected by the ridges and valleys of the finger is different, and the difference in energy is converted into a difference in electrical signals, i.e., the ridges and valleys of the fingerprint can be imaged, and then the fingerprint can be identified.

[0139] Optionally, the device can also be a device applied to a medical ultrasonic detection device for medical detection, such as a B-ultrasound, color photographic detection device, etc.

[0140] Since the principle of solving the problem of the device is similar to the above-mentioned ultrasonic transduction substrate, the implementation of the device can refer to the implementation of the above-mentioned ultrasonic transduction substrate, and the repeated parts will not be described again.

[0141] The embodiments of the present disclosure provide an ultrasonic transduction substrate, a manufacturing method thereof, and a device. The ultrasonic emission structure can emit ultrasonic waves, and the ultrasonic receiving structure can receive ultrasonic waves. Compared with the integrated structure of emission and reception in the related art, the separate structure of emission and reception in the present disclosure can be independently controlled, so that the materials and structures of the ultrasonic emission structure and the ultrasonic receiving structure can be designed specifically, thereby facilitating the improvement of the working performance of the ultrasonic emission structure and the ultrasonic receiving structure. Moreover, the ultrasonic receiving structure surrounds the ultrasonic emission structure, which can avoid the crosstalk of the reflected ultrasonic signals between the ultrasonic receiving structures, reduce the noise of the signals, improve the signal-to-noise ratio, and thus improve the imaging quality and clarity.

[0142] Although the preferred embodiments of the present disclosure have been described, those skilled in the art can make additional changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all changes and modifications falling within the scope of the present disclosure.

[0143] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present disclosure without departing from the spirit and scope of the embodiments of the present disclosure. Thus, if these modifications and variations of the embodiments of the present disclosure fall within the scope of the claims of the present disclosure and their equivalent technologies, the present disclosure also intends to include these modifications and variations.

Claims

1. An ultrasonic transduction substrate, wherein, The ultrasonic transducer unit comprises a substrate and a plurality of ultrasonic transducer units arranged on the substrate, wherein the ultrasonic transducer unit comprises: an ultrasonic transmitting structure configured to convert a received electrical signal into an ultrasonic wave signal; an ultrasonic receiving structure, a normal projection of the ultrasonic receiving structure on the substrate surrounds a normal projection of the ultrasonic transmitting structure on the substrate, the ultrasonic receiving structure is configured to output an electrical signal after converting a received ultrasonic wave signal; a driving circuit arranged between the substrate and the ultrasonic receiving structure, and the driving circuit is electrically connected with the ultrasonic receiving structure, the driving circuit is configured to receive the electrical signal output by the ultrasonic receiving structure.

2. The ultrasonic transduction substrate of claim 1, wherein, The ultrasonic transmitting structure comprises: a cavity arranged close to the substrate; a first passivation layer arranged on a side of the cavity away from the substrate, a normal projection of the first passivation layer on the substrate covers a normal projection of the cavity on the substrate; a first electrode arranged on a side of the first passivation layer away from the substrate, the first electrode is configured to receive a driving voltage; a first piezoelectric structure arranged on a side of the first electrode away from the substrate; a second electrode arranged on a side of the first piezoelectric structure away from the substrate, the second electrode is grounded.

3. The ultrasonic transduction substrate of claim 2, wherein, The ultrasonic transmitting structure further comprises an etching hole in communication with the cavity, and a normal projection of the first passivation layer on the substrate does not overlap with a normal projection of the etching hole on the substrate.

4. The ultrasonic transduction substrate of claim 3, wherein, A normal projection shape of the first passivation layer on the substrate is the same as a normal projection shape of the cavity on the substrate.

5. The ultrasonic transduction substrate of claim 4, wherein, A ratio of a size of the first passivation layer to a size of the cavity is greater than or equal to 1.2 and less than or equal to 1.

5.

6. The ultrasonic transduction substrate of any of claims 3-5, wherein, A plurality of the ultrasonic transducer units are arranged in an array on the substrate. Each of the etching holes corresponding to each of the cavities is independently arranged, or each of the etching holes corresponding to the cavities in the same column is in communication with each other.

7. The ultrasonic transduction substrate of claim 6, wherein, A normal projection shape of the first electrode on the substrate comprises a circular shape or a square shape.

8. The ultrasonic transduction substrate of claim 7, wherein, The ultrasonic receiving structure comprises: a third electrode arranged spaced apart from the first electrode, the third electrode and the first electrode are located on the same side of the cavity, and a normal projection of the third electrode on the substrate surrounds a normal projection of the first electrode on the substrate, the third electrode is electrically connected with the driving circuit; a second piezoelectric structure arranged on a side of the third electrode away from the substrate; a fourth electrode arranged on a side of the second piezoelectric structure away from the substrate, the fourth electrode is grounded.

9. The ultrasonic transduction substrate of claim 8, wherein, The first electrode and the third electrode are arranged in the same layer.

10. The ultrasonic transduction substrate of claim 8, wherein, The first electrode and the third electrode are arranged in different layers, and a second passivation layer is arranged between the first electrode and the third electrode.

11. The ultrasonic transduction substrate of claim 10, wherein, The first electrode is arranged close to the substrate, or the third electrode is arranged close to the substrate.

12. The ultrasonic transduction substrate of any of claims 9-11, wherein, The second electrode and the fourth electrode are an integral structure arranged in an entire surface, and the first piezoelectric structure and the second piezoelectric structure are an integral structure arranged in an entire surface.

13. The ultrasonic transduction substrate of any of claims 9-11, wherein, The second electrode and the fourth electrode are spaced apart, and a projection of the fourth electrode on the substrate substrate surrounds a projection of the second electrode on the substrate substrate; The first piezoelectric structure and the second piezoelectric structure are spaced apart, and a projection of the second piezoelectric structure on the substrate substrate surrounds a projection of the first piezoelectric structure on the substrate substrate.

14. The ultrasonic transduction substrate of claim 13, wherein, Further comprising: A third passivation layer is provided between the first electrode and / or the third electrode and the first piezoelectric structure, and an organic layer is provided between the first electrode and / or the third electrode and the first passivation layer.

15. The ultrasonic transduction substrate of claim 14, wherein, Further comprising a first overlap electrode which is in the same layer as the cavity and is spaced apart, the third electrode is electrically connected with the first overlap electrode, and the first overlap electrode is electrically connected with the driving circuit; wherein, The cavity and the first overlap electrode are peripherally filled with a resin layer.

16. The ultrasonic transduction substrate of claim 15, wherein, The material of the first piezoelectric structure and the material of the second piezoelectric structure include polyvinylidene fluoride.

17. An apparatus, wherein, The ultrasonic transduction substrate comprises the ultrasonic transduction substrate according to any one of claims 1-16.

18. A method of fabricating an ultrasonic transduction substrate for use in the ultrasonic transduction substrate of any one of claims 1-16, wherein, The manufacturing method comprises: Providing a substrate substrate; Forming a plurality of ultrasonic transduction units on one side of the substrate substrate; Forming the ultrasonic transduction unit comprises: Providing a driving circuit on one side of the substrate substrate; Forming an ultrasonic transmitting structure and an ultrasonic receiving structure on the side of the driving circuit away from the substrate substrate, the driving circuit is electrically connected with the ultrasonic receiving structure, and a projection of the ultrasonic receiving structure on the substrate substrate surrounds a projection of the ultrasonic transmitting structure on the substrate substrate; wherein, the ultrasonic transmitting structure is configured to convert the received electrical signal into an ultrasonic wave signal, the ultrasonic receiving structure is configured to convert the received ultrasonic wave signal into an electrical signal and output, and the driving circuit is configured to receive the electrical signal output by the ultrasonic receiving structure.

19. The production method according to claim 18, wherein The ultrasonic transmitting structure comprises a cavity, a first passivation layer, a first electrode, a first piezoelectric structure and a second electrode which are sequentially stacked; wherein, the cavity is formed by: Forming a metal film on the side away from the substrate substrate, the metal film comprises a cavity area, a non-cavity area and an etching hole area, and the etching hole area is in communication with the cavity area; Etching the non-cavity area to remove the metal in the non-cavity area; Filling a resin layer in the non-cavity area where the metal is removed; Forming the first passivation layer on the side of the cavity area away from the substrate substrate, etching the first passivation layer so that a projection of the first passivation layer on the substrate substrate covers a projection of the cavity area on the substrate substrate, and the projection of the first passivation layer on the substrate substrate does not overlap with the projection of the etching hole area on the substrate substrate; Injecting etching liquid into the etching hole area, and etching the cavity area to remove the metal in the cavity area to form the cavity.

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