Ultrasonic micro piezoelectric sensor chip, preparation method thereof and sound wave directional control method

Abstract

The invention discloses an ultrasonic miniature piezoelectric sensor chip, a preparation method thereof and a sound wave directional control method, and relates to the technical field of chips, the ultrasonic miniature piezoelectric sensor chip comprises a first substrate, a second substrate, a first sensing unit and a second sensing unit; the second substrate and the first substrate are arranged at an interval; the first sensing unit comprises a first vibrating membrane, a first bottom electrode, a first piezoelectric layer and a first top electrode which are stacked in sequence, and the two sides of the first vibrating membrane are connected with the first substrate and the second substrate respectively; the second sensing unit comprises a second vibrating membrane, a second bottom electrode, a second piezoelectric layer and a second top electrode which are stacked in sequence, and the two sides of the second vibrating membrane are connected with the first substrate and the second substrate respectively; the first substrate, the second substrate, the first vibrating diaphragm and the second vibrating diaphragm form a hollow cavity. According to the invention, the vibrating diaphragms at the two sides can work efficiently, good electrical isolation and interconnection can be realized, and the acoustic characteristics of the intermediate medium can be controlled.

Description

Technical Field

[0001] This invention relates to the field of chip technology, and in particular to an ultrasonic micro piezoelectric sensor chip, its fabrication method, and a method for directional control of acoustic waves. Background Technology

[0002] Traditional ultrasonic MEMS piezoelectric sensors typically employ a single-sided structure, fabricating a vibrating film and depositing a piezoelectric stack on a silicon substrate, with a back cavity etched underneath to achieve vibration. This structure has inherent limitations: (1) Poor acoustic crosstalk and directionality, with sound waves radiating to both sides, necessitates the addition of sound insulation structures on the non-working side to eliminate interference, resulting in complex devices and increased size; (2) Complex structure and low integration, with additional acoustic isolation or sound-absorbing components increasing process difficulty and cost, restricting device miniaturization and high-density integration; (3) Single function, with single-cavity design making it difficult to achieve dynamic sound field control on the same device, resulting in insufficient application flexibility. The root cause of these problems lies in the fact that its acoustic oscillator is limited to a single plane, which poses a severe challenge to constructing a symmetrical composite structure at the micrometer scale that can independently control sound waves on both sides and has both good electrical and acoustic performance. Existing processes cannot achieve this without introducing solid-state sound transmission paths and signal interference. Summary of the Invention

[0003] The main objective of this invention is to propose an ultrasonic micro piezoelectric sensor chip, its fabrication method, and a sound wave directional control method, which aims to ensure efficient operation of the two vibrating diaphragms, achieve good electrical isolation and interconnection, and control the acoustic properties of the intermediate medium.

[0004] To achieve the above objectives, the present invention proposes an ultrasonic miniature piezoelectric sensor chip, the ultrasonic miniature piezoelectric sensor chip comprising: First substrate; The second substrate is arranged at a distance from the first substrate; A first sensing unit, comprising a first vibrating diaphragm, a first bottom electrode, a first piezoelectric layer, and a first top electrode stacked sequentially, wherein the two sides of the first vibrating diaphragm are respectively connected to the first substrate and the second substrate; and The second sensing unit includes a second vibrating diaphragm, a second bottom electrode, a second piezoelectric layer, and a second top electrode stacked sequentially. The two sides of the second vibrating diaphragm are respectively connected to the first substrate and the second substrate. The first substrate, the second substrate, the first vibrating diaphragm, and the second vibrating diaphragm together form a hollow cavity. The first bottom electrode is electrically connected to the second bottom electrode, the first top electrode and the second top electrode are electrically insulated from each other and can be controlled independently, and the side of the first top electrode facing away from the first piezoelectric layer and the side of the second top electrode facing away from the second piezoelectric layer are arranged symmetrically.

[0005] In one embodiment, both the first top electrode and the second top electrode include multiple electrode units, and the multiple electrode units are arranged at intervals so that each of the multiple electrode units can be controlled independently.

[0006] In one implementation, The number of electrode units is two, one of which is an inner circular electrode and the other is an outer ring electrode. The inner circular electrode is located inside the outer ring electrode and is spaced apart from the outer ring electrode.

[0007] In one implementation, The outer ring electrode is also connected to a first connecting segment for connection to an external circuit; the outer ring electrode has a notch spaced apart from the first connecting segment, and the inner ring electrode is connected to a second connecting segment, which extends from the notch for connection to an external circuit.

[0008] In one embodiment, the ultrasonic micro piezoelectric sensor chip further includes a bottom connection segment, which is fixed to one of the first substrate and the second substrate and is used to connect the first bottom electrode and the second bottom electrode.

[0009] In one embodiment, the ultrasonic micro piezoelectric sensor chip further includes two extension segments, which are respectively connected to the first bottom electrode and the second bottom electrode, and are also connected to the bottom connection segment. The two extension segments extend in opposite directions.

[0010] In one embodiment, the ultrasonic micro piezoelectric sensor chip further includes two top connection segments, which are respectively connected to the first top electrode and the second top electrode, and the two top connection segments are fixed to the other of the first substrate and the second substrate; the two top connection segments extend in opposite directions.

[0011] In one embodiment, the first and / or second diaphragm is made of polycrystalline silicon.

[0012] In one embodiment, the hollow cavity is a vacuum cavity, or filled with an inert gas or an oxygen-adsorbing gel.

[0013] In one embodiment, the first and / or second diaphragm are provided with one or more through holes.

[0014] This invention also proposes a method for fabricating an ultrasonic micro piezoelectric sensor chip as described above, characterized in that the steps of the method for fabricating the ultrasonic micro piezoelectric sensor chip include: Provide a first substrate and a second substrate; A first oscillating film, a first bottom electrode, a first piezoelectric layer, and a first top electrode are sequentially formed on the first substrate, and a second oscillating film, a second bottom electrode, a second piezoelectric layer, and a second top electrode are sequentially formed on the second substrate. The first substrate and the second substrate are subjected to back cavity etching to form two cavities; In a vacuum environment, the first substrate and the second substrate are bonded together using a silicon-silicon bonding process, so that the two cavities are joined together to form a hollow cavity.

[0015] The present invention also proposes a method for directional control of acoustic waves, the method comprising the following steps: Target for receiving sound field modulation; Based on the sound field modulation target, the target operating mode of the ultrasonic micro piezoelectric sensor chip is determined, and the corresponding electrical signal parameters for driving the first top electrode and the second top electrode of the ultrasonic micro piezoelectric sensor chip are output; wherein, the electrical signal parameters include at least the phase and amplitude associated between the driving signals independently applied to the first top electrode and the second top electrode; Based on the electrical signal parameters, corresponding driving signals are generated and applied to the first and second top electrodes to enable the ultrasonic micro piezoelectric sensor chip to generate a sound field that matches the sound field modulation target.

[0016] In one embodiment, after the step of generating and applying corresponding driving signals to the first and second top electrodes according to the electrical signal parameters, so that the ultrasonic micro piezoelectric sensor chip generates a sound field matching the sound field modulation target, the method further includes: Based on the updated sound field control target, the above steps are dynamically repeated to switch the operating mode of the ultrasonic micro piezoelectric sensor chip and the generated sound field.

[0017] The technical solution of this invention involves symmetrically arranging a double-sided vibrating diaphragm structure, including a first sensing unit and a second sensing unit, between a first substrate and a second substrate, and enclosing it to form a hollow cavity. Simultaneously, the two bottom electrodes are electrically connected, and the two top electrodes are independently controlled and symmetrically arranged. First, the back-to-back symmetrical arrangement of the first and second vibrating diaphragms constitutes a natural double-sided acoustic wave radiation / receiving surface. Sound waves can propagate independently on both sides through the hollow cavity, thereby physically isolating acoustic interference from the non-working side. This significantly reduces acoustic crosstalk and enhances directionality without the need for additional sound insulation structures. Second, the shared first and second bottom electrodes simplify the electrical connection and ensure consistency in diaphragm driving / sensing, while the first top electrode and the second bottom electrode... Independent control of the top electrode allows for separate excitation and reading of the two diaphragms, achieving not only excellent electrical isolation and interconnection but also enabling the independent adjustment of the phase and amplitude of the two diaphragms via electrical signals. This dynamically shapes the acoustic field characteristics within the hollow cavity, enabling multi-functional acoustic control such as beam guiding and focusing, overcoming the limitations of traditional single-cavity designs. Ultimately, the overall structure, with the symmetrical arrangement of the first and second top electrodes and the shared hollow cavity, ensures efficient, synchronous, or differential operation of the two diaphragms while flexibly controlling acoustic performance by adjusting the acoustic boundary conditions of the central cavity. This achieves a high-integration, reconfigurable ultrasonic sensing chip with balanced electroacoustic performance at the microscale. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an embodiment of the ultrasonic miniature piezoelectric sensor chip provided by the present invention; Figure 2 This is a schematic diagram of the electrode unit structure of the ultrasonic micro piezoelectric sensor chip provided by the present invention; Figure 3 This is a schematic flowchart illustrating the steps of the fabrication method of the ultrasonic micro piezoelectric sensor chip provided by the present invention. Figure 4 This is a flowchart illustrating the steps of the acoustic wave directional control method provided by the present invention.

[0020] Explanation of icon numbers: 10. First substrate; 20. Second substrate; 30. First sensing unit; 31. First vibrating diaphragm; 32. First bottom electrode; 33. First piezoelectric layer; 34. First top electrode; 40. Second sensing unit; 41. Second vibrating diaphragm; 42. Second bottom electrode; 43. Second piezoelectric layer; 44. Second top electrode; 1. Hollow cavity; 2. Electrode unit; 2a. Inner circular electrode; 21a. Notch; 22a. Second connecting segment; 2b. Outer ring electrode; 21b. First connecting segment; 3. Bottom connecting segment; 4. Extension segment; 5. Top connecting segment; 6. Through hole.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0024] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0025] In the design of traditional ultrasonic micro piezoelectric sensor chips, acoustic crosstalk causes signal interference, insufficient directional performance affects the accuracy of sound field control, structural complexity restricts the improvement of device integration, and the single function makes dynamic sound field modulation difficult to achieve. Specifically, in a single-sided structure, sound waves radiate to the non-working side, requiring the introduction of additional acoustic isolation components to eliminate interference. This not only increases the number of process steps and material consumption but also leads to an increase in chip size. The single-cavity design cannot achieve dynamic switching of sound field direction on the same device, limiting the device's adaptability in complex acoustic environments.

[0026] For example, in high-density sensor array applications of ultrasound medical imaging systems, traditional single-sided sensor chips cause significant acoustic crosstalk between adjacent units due to the indiscriminate radiation of sound waves to both sides, resulting in decreased image resolution and artifacts. The sound insulation structure added to suppress interference increases the chip thickness, making it difficult to meet the miniaturization requirements of portable devices. At the same time, the single-cavity design only supports a single working mode and cannot dynamically adjust the sound field direction during real-time monitoring, making the system unable to adapt to changing imaging needs.

[0027] For this, please refer to Figure 1 and Figure 2 This application proposes an ultrasonic micro piezoelectric sensor chip including a first substrate 10, a second substrate 20, a first sensing unit 30, and a second sensing unit 40; the second substrate 20 and the first substrate 10 are arranged at intervals; the first sensing unit 30 includes a first vibrating diaphragm 31, a first bottom electrode 32, a first piezoelectric layer 33, and a first top electrode 34 stacked sequentially, with the two sides of the first vibrating diaphragm 31 connected to the first substrate 10 and the second substrate 20 respectively; the second sensing unit 40 includes a second vibrating diaphragm 41 and a second bottom electrode stacked sequentially. 42. The second piezoelectric layer 43 and the second top electrode 44, and the two sides of the second vibrating membrane 41 are respectively connected to the first substrate 10 and the second substrate 20; the first substrate 10, the second substrate 20, the first vibrating membrane 31 and the second vibrating membrane 41 enclose a hollow cavity 1; wherein, the first bottom electrode 32 and the second bottom electrode 42 are electrically connected, the first top electrode 34 and the second top electrode 44 are electrically insulated from each other and can be independently controlled, and the side of the first top electrode 34 facing away from the first piezoelectric layer 33 and the side of the second top electrode 44 facing away from the second piezoelectric layer 43 are symmetrically arranged.

[0028] In this embodiment, the first substrate 10 and the second substrate 20 are arranged at intervals to form a stable mechanical support frame. This frame is made of silicon-based materials, such as single-crystal silicon or glass, mainly to provide fixed connection points for the vibrating diaphragm and maintain structural stability.

[0029] Furthermore, the two sides of the first vibrating diaphragm 31 and the second vibrating diaphragm 41 are respectively connected to the first substrate 10 and the second substrate 20 to form a hollow cavity 1. The hollow cavity 1 refers to a closed space region jointly enclosed by the first vibrating diaphragm 31, the second vibrating diaphragm 41, the first substrate 10 and the second substrate 20.

[0030] Specifically, the first sensing unit 30 includes a first vibrating diaphragm 31, a first bottom electrode 32, a first piezoelectric layer 33, and a first top electrode 34 stacked sequentially. The first vibrating diaphragm 31 can be made of polycrystalline silicon or silicon nitride, primarily to optimize mechanical vibration response characteristics. The second sensing unit 40 includes a second vibrating diaphragm 41, a second bottom electrode 42, a second piezoelectric layer 43, and a second top electrode 44 stacked sequentially. The first bottom electrode 32 and the second bottom electrode 42 are electrically connected. This connection can be achieved by sharing a conductive lead, for example, by directly connecting a metal wire to an external reference potential point, primarily to simplify the wiring complexity of the shared reference electrode.

[0031] In practical applications, the first top electrode 34 and the second top electrode 44 are electrically insulated from each other and can be controlled independently. Mutual electrical insulation means that they are electrically isolated through an insulating structure, which can be achieved by depositing an insulating layer on the substrate surface, such as silicon dioxide or silicon nitride insulating layers, primarily to achieve electrical isolation between the electrodes. Independent control means that each top electrode can be individually charged with an electrical signal, which can be achieved by connecting each top electrode to an external circuit, for example, by connecting it to a control unit via independent wires or pads, primarily to achieve precise control of the sound field on both sides. Thus, the side of the first top electrode 34 facing away from the first piezoelectric layer 33 and the side of the second top electrode 44 facing away from the second piezoelectric layer 43 are symmetrically arranged. This symmetrical arrangement means that the geometry and position of the top electrodes are symmetrical about the center of the hollow cavity 1, which can be achieved using a circular or annular structure, for example, the top electrodes can be designed as concentric circles or symmetrical polygons, primarily to ensure the uniformity of the sound field distribution. This structure, through the symmetrical layout of dual sensing units and the isolation design of the hollow cavity 1, effectively avoids the defect of sound waves radiating to the non-working side in the traditional single-sided structure, thereby realizing sound wave path isolation and dynamic sound field control at the micron scale.

[0032] The overall structure of the ultrasonic micro piezoelectric sensor chip consists of a first substrate 10 and a second substrate 20, which are arranged at intervals to form a stable mechanical support frame. The first sensing unit 30 includes a first vibrating diaphragm 31, a first bottom electrode 32, a first piezoelectric layer 33, and a first top electrode 34 stacked sequentially. The two sides of the first vibrating diaphragm 31 are connected to the first substrate 10 and the second substrate 20, respectively. The second sensing unit 40 includes a second vibrating diaphragm 41, a second bottom electrode 42, a second piezoelectric layer 43, and a second top electrode 44 stacked sequentially. The two sides of the second vibrating diaphragm 41 are also connected to the first substrate 10 and the second substrate 20. The first substrate 10, the second substrate 20, the first vibrating diaphragm 31, and the second vibrating diaphragm 41 together form a hollow cavity 1. This hollow cavity 1 serves as an acoustic isolation zone, effectively blocking the solid-borne sound transmission path and preventing sound wave radiation interference to the non-working side. The first bottom electrode 32 and the second bottom electrode 42 are electrically connected, simplifying the wiring complexity of the shared reference electrode. The first top electrode 34 and the second top electrode 44 are electrically insulated from each other and can be controlled independently. They are symmetrically arranged on the side opposite to the piezoelectric layer, allowing the electrical signal applied by the external circuit to precisely control the sound field distribution on both sides. When a driving signal is applied to the top electrode, the piezoelectric layer deforms under the action of the electric field, causing the diaphragm to vibrate mechanically, thereby emitting sound waves. Due to the isolation effect of the hollow cavity 1, the sound waves propagate only in the expected direction, and the differentiated connection design of the electrodes ensures the independence and accuracy of signal control.

[0033] In one specific embodiment, both the first substrate 10 and the second substrate 20 are made of silicon to provide good mechanical strength and process compatibility; the first diaphragm 31 and the second diaphragm 41 are made of silicon nitride, optimizing the sensitivity and stability of the vibration response. The hollow cavity 1 is vacuum-treated during manufacturing to further enhance the acoustic isolation effect. The first bottom electrode 32 and the second bottom electrode 42 are electrically connected through the bottom connecting section 3, while the first top electrode 34 and the second top electrode 44 each have independent signal lines for receiving external control commands. For example, in a directional sound wave emission scenario, applying a driving signal with opposite phase to the first top electrode 34 and the second top electrode 44 can cause the two diaphragms to vibrate in opposite directions, thereby concentrating the sound wave energy in a single direction; in the sound wave transmission mode, the first top electrode 34 acts as a transmitter to drive vibration, and the second top electrode 44 acts as a receiver to collect signals, achieving efficient acoustic information interaction.

[0034] Therefore, this technical solution significantly reduces acoustic crosstalk and improves sound wave directionality through the acoustic isolation mechanism of the hollow cavity 1; the independent control design of the electrodes avoids the introduction of additional sound insulation structures, simplifies the device structure, and improves integration; the symmetrical arrangement of the top electrodes ensures the accuracy of sound field modulation, enabling the device to flexibly switch operating modes and effectively solves the problem of limited functionality caused by traditional single-sided structures. Overall, it achieves sound wave path isolation and dynamic modulation at the micrometer scale, meeting the performance requirements of miniaturized sensors for high-density integrated applications.

[0035] For this, please refer to Figure 1 and Figure 2 This application further proposes that both the first top electrode 34 and the second top electrode 44 include multiple electrode units 2, and the multiple electrode units 2 are arranged at intervals so that each of the multiple electrode units 2 can be controlled independently.

[0036] Among them, electrode unit 2 refers to the independent functional area into which the first top electrode 34 and the second top electrode 44 are divided. It can be implemented by a conductive structure of circular, fan-shaped, ring-shaped or rectangular shape, etc., in order to achieve zoned control of the sound field; the spaced arrangement means that the electrode units 2 are physically isolated from each other. It can be implemented by an insulating structure such as a silicon dioxide isolation layer or an air gap, in order to prevent electrical signal interference between adjacent units; each independent control means that each electrode unit 2 can apply or read electrical signals independently. It can be implemented by connecting to a multiplexed control circuit with an independent wire, in order to support differentiated signal processing for different areas.

[0037] Specifically, the solution in this application refines the first top electrode 34 and the second top electrode 44 into multiple independent units, ensuring that these units are arranged at intervals, thereby forming a reliable electrical isolation environment in terms of physical structure. Based on this, by independently controlling the electrical signals applied to each electrode unit 2, the diaphragm can be driven to produce a localized vibration response, avoiding the problem of uniform sound wave radiation caused by monolithic electrodes. This design allows the sensor to dynamically adjust the vibration state of each region according to actual application requirements. Combined with the acoustic characteristics of the hollow cavity 1, it achieves spatially selective control of the sound field, providing a structural basis for directional sound wave emission and multi-mode reception.

[0038] Through the above-mentioned scheme, this application can improve the directionality of sound wave radiation, reduce acoustic interference from non-target directions, and enhance the signal capture capability of sound sources in specific directions in receiving mode, thereby meeting the needs of high-precision directional transmission and dynamic sound field optimization.

[0039] Please see Figure 1 and Figure 2This application further proposes that there are two electrode units 2, one of which is an inner circular electrode 2a and the other is an outer ring electrode 2b. The inner circular electrode 2a is located inside the outer ring electrode 2b and is spaced apart from the outer ring electrode 2b.

[0040] The term "two electrode units 2" refers to dividing the top electrode into two independent electrode regions. These regions can be implemented using symmetrical or asymmetrical layouts to balance circuit complexity and acoustic field control freedom, avoiding wiring difficulties caused by too many units. The inner circular electrode 2a can be understood as a circular electrode structure located in the center region of the diaphragm. It can be formed using metal thin-film deposition processes, such as defining a circular pattern through photolithography and etching techniques. Its purpose is to concentrate the electric field distribution to enhance the vibration response of the central region. The outer ring electrode 2b refers to the annular electrode surrounding the inner circular electrode 2a. It can be implemented using the same layout as the inner circular electrode 2a. The same material system is used, but it is achieved through a ring mask design. The purpose is to expand the electric field coverage to regulate the edge acoustic radiation characteristics. The inner circular electrode 2a is located inside the outer ring electrode 2b, which means that the inner circular electrode 2a is completely surrounded by the outer ring electrode 2b. It can be designed with concentric circles to ensure the axial symmetry of the electric field distribution. The purpose is to generate a uniform and predictable acoustic wave pattern. The spacing setting can be understood as the existence of a physical gap between the inner circular electrode 2a and the outer ring electrode 2b. It can be filled with insulating material or an air gap to achieve electrical isolation. The purpose is to prevent signal crosstalk and ensure the independent control capability of each electrode unit 2.

[0041] Specifically, the scheme of this application, through the concentric arrangement of the inner circular electrode 2a and the outer ring electrode 2b, enables the electric field applied to the top electrode to form an axisymmetric distribution on the diaphragm, thereby generating a uniform sound wave radiation mode during driving; at the same time, the spacing ensures the stability of electrical isolation, allowing signals of different phases or amplitudes to be applied to the inner circular electrode 2a and the outer ring electrode 2b, thereby precisely guiding the direction of the sound wave through the difference in electric field distribution, and realizing the directional emission function; this structural combination simplifies the electrode interconnection path while retaining the basic sound field control capability, forming a complete acoustic control mechanism.

[0042] In a preferred embodiment, the inner circular electrode 2a of this application may specifically be a circular metal electrode layer deposited in the central region of the vibrating membrane, and the outer ring electrode 2b is an annular metal electrode layer surrounding the outer periphery of the inner circular electrode 2a. The two are formed into a uniform annular gap by photolithography, and the gap is filled with silicon dioxide insulating material. The inner circular electrode 2a is connected to the external circuit through a central lead, and the outer ring electrode 2b is connected to the external circuit through an annular edge lead. The lead path extends radially along the vibrating membrane to avoid cross-interference.

[0043] As a preferred embodiment, the first top electrode 34 of this application includes three fan-shaped electrode units 2 arranged at 120-degree intervals. Each electrode unit 2 extends to the edge of the first substrate 10 through an independent connecting segment and is connected to an external control circuit, thereby allowing a phase- or amplitude-differentiated drive signal to be applied to each fan-shaped region.

[0044] Through the above scheme, the acoustic radiation mode of this application can be precisely controlled, the electrode interconnection structure is simplified and signal interference is effectively suppressed, thereby improving the directional emission reliability and miniaturization integration capability of the sensor.

[0045] However, during its implementation, due to the continuous ring design of the outer ring electrode 2b, the connecting line of the inner circular electrode 2a cannot be led out from the inside of the outer ring electrode 2b to the external circuit, resulting in wiring path conflicts, increased risk of short circuit between electrodes, and inability to ensure electrical isolation and independent signal control of the two electrode units 2.

[0046] For this, please refer to Figure 1 and Figure 2 This application further proposes that the outer ring electrode 2b is also connected to a first connecting segment 21b for connection to an external circuit; the outer ring electrode 2b has a notch 21a spaced apart from the first connecting segment 21b, and the inner ring electrode 2a is connected to a second connecting segment 22a, which extends from the notch 21a for connection to an external circuit.

[0047] The first connecting segment 21b refers to the conductive structure used to establish an electrical connection between the outer ring electrode 2b and the external circuit. It can be implemented using conductive materials such as metal wires or conductive films, and its purpose is to provide an external signal access point for the outer ring electrode 2b. The notch 21a refers to a partially disconnected area on the outer ring electrode 2b. It can be designed as an arc-shaped or straight opening, and its purpose is to provide a dedicated passage for the connecting line of the inner circular electrode 2a, avoiding electrical contact with the outer ring electrode 2b. The second connecting segment 22a refers to the conductive path connecting the inner circular electrode 2a and the external circuit. It can be implemented using thin metal wires or flexible wires, and its purpose is to realize independent signal control of the inner circular electrode 2a.

[0048] Specifically, the solution of this application arranges the first connecting segment 21b of the outer ring electrode 2b and the notch 21a at intervals, so that the notch 21a can accommodate the second connecting segment 22a of the inner circular electrode 2a to pass through. The first connecting segment 21b of the outer ring electrode 2b is directly connected to the external circuit, and the notch 21a acts as an isolation area to ensure that the second connecting segment 22a does not contact the outer ring electrode 2b during its passage. Thus, while maintaining the overall ring structure of the outer ring electrode 2b, electrical isolation between the inner circular electrode 2a and the outer ring electrode 2b is achieved, effectively solving the wiring conflict problem.

[0049] Through the above solution, this application effectively avoids wiring path conflicts and short-circuit risks between the inner circular electrode 2a and the outer ring electrode 2b, and ensures electrical isolation and independent signal control capabilities of the two electrode units 2.

[0050] Please see Figure 1 and Figure 2 This application further proposes that the ultrasonic micro piezoelectric sensor chip also includes a bottom connection segment 3, which is fixed to one of the first substrate 10 and the second substrate 20, and is used to connect the first bottom electrode 32 and the second bottom electrode 42.

[0051] In practical applications, the bottom connection segment 3 refers to a conductive structure for electrical connection, which can be implemented using metal wires, conductive polymer films, or sputtered metal layers, with the aim of providing a stable and reliable electrical connection path. The fact that it is fixed to one of the first substrate 10 and the second substrate 20 can be understood as the connection segment being integrated on the surface or inside of one of the first substrate 10 and the second substrate 20. Specifically, it can be a conductive pattern formed on one of the first substrate 10 and the second substrate 20 by photolithography, with the aim of using the rigidity of the substrate to ensure that the connection point remains stable during vibration.

[0052] Specifically, the connection segment used to connect the first bottom electrode 32 and the second bottom electrode 42 means that the connection segment directly bridges the first bottom electrode 32 and the second bottom electrode 42, avoiding indirect connection through dynamic components such as the first diaphragm 31 and the second diaphragm 41. The purpose is to eliminate signal interference and acoustic coupling caused by mechanical deformation.

[0053] Specifically, the solution of this application fixes the bottom connecting segment 3 to a rigid substrate of either the first substrate 10 or the second substrate 20, ensuring that the connecting segment remains stationary during sensor operation, thereby forming a stable electrical connection with the first bottom electrode 32 and the second bottom electrode 42. Since the first substrate 10 and the second substrate 20, as supporting structures, do not participate in vibration, this fixing method effectively isolates the influence of the mechanical movement of the first vibrating diaphragm 31, the second vibrating diaphragm 41, the first piezoelectric layer 33, and the second piezoelectric layer 43 on the electrical connection, preventing loosening of the connection and the generation of signal noise. Simultaneously, the direct connection path between the two bottom electrodes avoids indirect connection through the vibrating diaphragm, reducing the introduction of solid-borne sound transmission paths, maintaining the acoustic isolation performance of the hollow cavity 1, and ensuring the signal purity of the sensor during sound wave transmission and reception.

[0054] As a specific implementation, the bottom connection segment 3 of this application can be a single aluminum wire formed on the surface of the first substrate 10 by photolithography. One end of the wire is connected to the first bottom electrode 32, and the other end is connected to the second bottom electrode 42, thereby realizing the electrical connection between the two bottom electrodes.

[0055] Through the above solution, this application effectively solves the reliability problem of electrical connection between bottom electrodes, avoids the aggravation of signal interference during vibration and the accidental introduction of solid sound transmission path, thereby improving the acoustic directionality and operational reliability of the sensor.

[0056] Please see Figure 1 and Figure 2 This application further proposes that the ultrasonic micro piezoelectric sensor chip also includes two extension segments 4, which are respectively connected to the first bottom electrode 32 and the second bottom electrode 42, and connected to the bottom connection segment 3. The two extension segments 4 are respectively extended in opposite directions.

[0057] Specifically, extension segment 4 refers to the conductive structure connecting the bottom electrode and the bottom connection segment 3. It can be implemented using metal wires, conductive polymer films, or flexible printed circuits. The purpose is to provide mechanical flexibility to disperse vibration stress and avoid the rigid connection point directly transmitting vibration stress to the vibrating diaphragm.

[0058] Specifically, the solution of this application connects the first bottom electrode 32 and the second bottom electrode 42 to the extension section 4 respectively, and connects to the bottom connection section 3. The two extension sections 4 extend in opposite directions, so that when the diaphragm is working, the extension sections 4 can disperse the mechanical stress in opposite directions, avoid stress concentration, thereby reducing the interference of vibration deformation on the direction of sound wave emission, ensuring that the first diaphragm 31 and the second diaphragm 41 maintain a symmetrical vibration state under independent control, while maintaining the electrical connection requirements between the first bottom electrode 32 and the second bottom electrode 42.

[0059] As a specific implementation, the extension segment 4 of this application can be made of gold wire, with one end connected to the first bottom electrode 32 by welding and the other end connected to the bottom connecting segment 3. Similarly, another extension segment 4 is connected to the second bottom electrode 42 and the bottom connecting segment 3. The two extension segments 4 are arranged symmetrically to achieve opposite extensions.

[0060] Through the above-mentioned solution, this application effectively alleviates the stress concentration phenomenon during the operation of the diaphragm, improves the uniformity of vibration deformation, and thus improves the accuracy of directional sound wave emission and the independent control capability of the two diaphragms.

[0061] Please see Figure 1 and Figure 2 This application further proposes that the ultrasonic micro piezoelectric sensor chip also includes two top connection segments 5, which are respectively connected to the first top electrode 34 and the second top electrode 44, and the two top connection segments 5 are fixed to the other of the first substrate 10 and the second substrate 20; the two top connection segments 5 are respectively arranged to extend in opposite directions.

[0062] The top connection segment 5 refers to a conductive structure used to establish a dedicated electrical path for the top electrode. It can be made of metal thin film or conductive polymer material to ensure conductivity reliability and mechanical durability under high-frequency vibration environment. The other of the first substrate 10 and the second substrate 20 can be understood as choosing the substrate opposite to the bottom connection segment 3 as the anchor point. For example, when the bottom connection segment 3 is fixed to the first substrate 10, the top connection segment 5 is fixed to the second substrate 20. The purpose is to use the rigid support characteristics of the substrate to prevent displacement or breakage during vibration. The extension in the opposite direction is specifically a symmetrical epitaxial layout towards both sides of the chip. It can be designed as a straight line or an arc path. The purpose is to optimize external circuit integration and reduce the risk of wiring crossover and electromagnetic coupling.

[0063] Specifically, the solution in this application establishes independent electrical paths between the two top connection segments 5 and the first top electrode 34 and the second top electrode 44, respectively, and fixes them on a rigid substrate, thereby achieving precise isolation and stable transmission of the top electrodes. Since the top connection segments 5 are fixed to the substrate surface on the non-working side, mechanical disturbances during high-frequency operation of the diaphragm are effectively suppressed. Simultaneously, the opposing extension directions ensure that the connection points are symmetrically distributed on both sides of the chip, avoiding signal interference caused by shared paths. This ensures real-time independent operation of each top electrode, providing a physical basis for directional acoustic field control.

[0064] As a specific implementation, the top connection segment 5 of this application can be an aluminum conductive strip formed by sputtering process. One end of the strip is electrically connected to the top electrode, and the other end is fixed to the surface of the second substrate 20 and extends radially outward to the edge of the chip, which facilitates independent soldering with the external driving circuit.

[0065] Through the above scheme, the independent electrical connection of the top electrode can be reliably realized, effectively avoiding signal crosstalk problems and supporting the stable execution of multi-functional operations such as directional sound field emission and sound wave transmission, thereby improving the operational flexibility and functional reliability of the ultrasonic micro piezoelectric sensor chip in acoustic control applications.

[0066] Please see Figure 1 and Figure 2 Furthermore, this application proposes that the first diaphragm 31 and / or the second diaphragm 41 are made of polycrystalline silicon.

[0067] In practical applications, the first vibrating membrane 31 and / or the second vibrating membrane 41 can be made of polycrystalline silicon, a semiconductor material widely used in microelectromechanical systems (MEMS) processes, which has high mechanical strength and a thermal expansion coefficient that matches that of the silicon substrate. This material can be selected by using polycrystalline silicon thin films prepared by chemical vapor deposition, the purpose of which is to ensure that the vibrating membrane is not prone to fatigue fracture during ultrasonic high-frequency vibration and to reduce the accumulation of thermal stress during silicon-silicon bonding. In addition, the uniform microstructure of polycrystalline silicon supports the precise forming of micron-scale vibrating membranes and avoids local stress concentration caused by material defects.

[0068] Specifically, the solution of this application limits the material of the diaphragm to polycrystalline silicon, making it highly consistent with the first substrate 10 and the second substrate 20 in terms of thermal expansion coefficient. This significantly reduces the accumulation of thermal stress in the silicon-silicon bonding process and avoids the decrease in vacuum or leakage of the medium in the hollow cavity 1 due to stress deformation. At the same time, the mechanical strength of polycrystalline silicon ensures the structural integrity of the diaphragm under repeated high-frequency vibration, enabling the first diaphragm 31 and the second diaphragm 41 to achieve synchronous and consistent vibration response under independent electrode control. This effectively suppresses the radiation of sound waves to the non-working side and improves the sound field control capability.

[0069] As a specific implementation, the first diaphragm 31 and the second diaphragm 41 of this application are both made of polycrystalline silicon material formed by low-pressure chemical vapor deposition. This material forms a uniform micron-scale thin film on the silicon substrate, supports precise microstructure molding, and is bonded to the first substrate 10 and the second substrate 20 in a vacuum environment to ensure the sealing of the hollow cavity 1 and the stability of the acoustic environment.

[0070] Through the above-mentioned solution, this application effectively prevents mechanical fatigue of the diaphragm during high-frequency operation and residual stress in the bonding process, ensures the sealing of the hollow cavity 1, reduces acoustic crosstalk, and improves the accuracy of directional sound wave emission and device reliability.

[0071] Please see Figure 1 and Figure 2 Furthermore, this application proposes that the hollow cavity 1 is a vacuum cavity, or filled with an inert gas or an oxygen-adsorbing gel.

[0072] Specifically, a vacuum cavity refers to a space within which there are no gas molecules. It can be achieved using a vacuum pump to create a vacuum, with the aim of completely eliminating the reflection and energy dissipation of sound waves within the cavity. An inert gas can be a chemically stable gas such as argon or helium, which can be achieved using a gas injection process, with the aim of creating a vacuum environment in the hollow cavity 1. An oxygen-adsorbing gel refers to a gel material that can actively capture oxygen. It can be achieved using materials such as silica gel or molecular sieves, with the aim of creating a vacuum environment in the hollow cavity 1, ensuring internal dryness and stable pressure.

[0073] Specifically, the solution of this application fundamentally optimizes the acoustic environment by setting the hollow cavity 1 as a vacuum cavity, filling it with an inert gas, or using an oxygen-adsorbing gel. When a vacuum cavity is used, the lack of gas molecules inside prevents sound waves from propagating, thus eliminating intracavity reflections and energy dissipation. When filled with an inert gas, the chemical stability of the gas ensures a constant sound velocity, preventing sound waves from propagating through the air, thereby eliminating intracavity reflections and energy loss. When using an oxygen-adsorbing gel, the gel regulates the microenvironment by adsorbing oxygen, inhibiting oxidation processes and maintaining pressure stability, thereby reducing sound wave transmission interference. These mechanisms work synergistically to transform the hollow cavity 1 from a passive isolation structure into an active control unit, effectively suppressing acoustic crosstalk and enhancing response reliability.

[0074] In one specific implementation, the hollow cavity 1 of this application can be filled with argon gas as an inert gas, which is introduced and sealed through a microporous injection process; or, silica gel particles can be placed inside the hollow cavity 1 as an oxygen adsorption gel, which is fixed inside the cavity through a dispensing process.

[0075] Through the above scheme, acoustic wave reflection and attenuation in the hollow cavity 1 are effectively eliminated, acoustic crosstalk is reduced, and sensor directivity is improved; at the same time, the stability of the cavity environment is enhanced, and the consistency of device performance and environmental adaptability are improved.

[0076] Please see Figure 1 and Figure 2 This application further proposes that the first diaphragm 31 and / or the second diaphragm 41 are provided with one or more through holes 6.

[0077] Among them, the through hole 6 refers to the opening structure set on the vibrating diaphragm, which can be circular, square or polygonal in shape, etc. The purpose is to allow the medium inside the cavity to flow bidirectionally during vibration, so as to alleviate the pressure imbalance problem in the sealed state of the hollow cavity 1. The multiple through holes 6 can be set in a uniform distribution or asymmetrical arrangement, which aims to enhance the fault tolerance of the system through a multi-path flow mechanism and avoid performance fluctuations caused by the blockage of a single through hole 6.

[0078] Specifically, the solution of this application provides through holes 6 on the first diaphragm 31 and / or the second diaphragm 41, so that the medium in the hollow cavity 1 can quickly achieve pressure equalization through the through holes 6 when the diaphragm is deformed by the electric signal, thereby avoiding the increase in mechanical damping caused by local pressure accumulation. This structural design allows the diaphragm to respond more freely to the sound wave excitation, improves the stability of the vibration amplitude and the frequency response range, and ensures the realization of the acoustic isolation function.

[0079] As a preferred embodiment, the first diaphragm 31 of this application is provided with a plurality of circular through holes 6, which are arranged in a ring array along the surface of the diaphragm to allow the gas medium in the hollow cavity 1 to flow bidirectionally during vibration, thereby maintaining the dynamic balance of cavity pressure; the second diaphragm 41 is also provided with a similar through hole 6 structure to achieve symmetrical pressure regulation.

[0080] The above solution effectively reduces mechanical damping during vibration, improves the response speed and stability of the diaphragm, and thus improves the efficiency and directionality of sound wave transmission and reception.

[0081] Please see Figure 1 and Figure 3 The present invention also discloses a method for fabricating an ultrasonic micro piezoelectric sensor chip, the specific steps of which include: A first substrate 10 and a second substrate 20 are provided; A first resonant membrane 31, a first bottom electrode 32, a first piezoelectric layer 33 and a first top electrode 34 are sequentially formed on a first substrate 10, and a second resonant membrane 41, a second bottom electrode 42, a second piezoelectric layer 43 and a second top electrode 44 are sequentially formed on a second substrate 20. Back cavity etching is performed on the first substrate 10 and the second substrate 20 to form two cavities; In a vacuum environment, the first substrate 10 and the second substrate 20 are bonded together using a silicon-silicon bonding process, so that the two cavities are connected to form a hollow cavity 1.

[0082] First, two double-sided polished silicon wafers are provided as the first substrate 10 and the second substrate 20, respectively.

[0083] Etching and filling of the metal vias 6 (first stage). At specific locations on the first substrate 10, vias 6 are formed using photolithography and deep reactive ion etching (DRIE). Subsequently, the vias 6 are filled with tungsten (W) or copper (Cu) using chemical vapor deposition (CVD) or electroplating to form the metal vias 6, achieving vertical electrical interconnection. To precisely control the thickness of the subsequent oscillating film, a layer of silicon oxide can be thermally grown on the surface of the first substrate 10 as an etch stop layer. Similarly, the second substrate 20 undergoes the same treatment.

[0084] On the front side of the two substrates, a layer of polycrystalline silicon is deposited using low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD) to form the prototype of the first resonant film 31 and the second resonant film 41, with a thickness of approximately 0.100 μm.

[0085] Subsequently, a seed layer (AlN or PZT) and a bottom electrode metal layer (such as Mo / Al) are deposited by sputtering, and patterned by photolithography and etching processes to form the first bottom electrode 32.

[0086] A first piezoelectric layer 33 and a second piezoelectric layer 43 are sputtered and deposited on the first bottom electrode 32 and the second bottom electrode 42, preferably made of aluminum nitride (AlN) or lead zirconate titanate (PZT). The piezoelectric layers are then patterned using a reactive ion etching (RIE) process.

[0087] Next, a top electrode metal layer (such as Al) is sputtered and deposited on the first piezoelectric layer 33, and a first top electrode 34 is patterned. Then, a top electrode metal layer (such as Al) is sputtered and deposited on the second piezoelectric layer 43, and a second top electrode 44 is patterned. This step is one of the key improvements: through a fine photolithography process, the first top electrode 34 and the second top electrode 44 are patterned into a structure with separate inner and outer rings, namely an inner circular electrode 2a and an outer ring electrode 2b, which are electrically isolated.

[0088] Polysilicon layers are deposited on the first substrate 10 and the second substrate 20, and patterned to form a certain support structure and bonding region. This polysilicon layer mainly serves as a support structure and provides a flat surface for subsequent bonding. The metal vias 6 are filled (second time). On another second substrate 20 (i.e., the silicon wafer corresponding to the right-side sensing unit), photolithography and deep reactive ion etching (DRIE) processes are repeatedly used to form vias 6, creating a symmetrical metal via structure.

[0089] After completing the above thin film stack preparation, the back cavity etching step is performed. The first substrate 10 and the second substrate 20 are processed on the back side: deep reactive ion etching (DRIE) is performed to form the cavity from the back side. Using the grown silicon oxide layer as an etching stop layer, the final thickness of the first and second resonant films 31 and the depth and shape of the cavity can be precisely controlled. This step precisely controls the etching depth and cavity size, preparing for the subsequent formation of the hollow cavity 1.

[0090] The crucial bonding steps are performed in a vacuum environment. The first substrate 10, with its front-side thin film stacking and back-side cavity etching completed, is aligned with the second substrate 20, so that their front sides (i.e., the sides with the vibrating film and electrodes) face each other, and the openings of the first and second cavities are aligned with each other. Subsequently, using silicon-to-silicon direct bonding or anodic bonding processes, the two substrates are firmly bonded together in a vacuum environment. During this process, the edge regions of the first vibrating film 31 and the second vibrating film 41 are connected to the bonding surfaces of the first substrate 10 and the second substrate 20, respectively, thereby connecting and communicating the first and second cavities to form a sealed hollow cavity 1. The vacuum environment ensures that the interior of the hollow cavity 1 is in a vacuum or low-pressure state, which is beneficial for the vibrating film to achieve low-damping and high-efficiency vibration.

[0091] After bonding is complete, subsequent interconnection processes can be performed. For example, the connection area between the first bottom electrode 32 and the second bottom electrode 42 can be etched through the via 6 (or the connection structure can be pre-designed during fabrication), and metal filling can be used to achieve electrical connection between the two. Finally, pads are fabricated on the chip surface to bring out the first top electrode 34, the second top electrode 44, and the common bottom electrode for packaging and external circuit connection, thereby completing the fabrication of the entire ultrasonic micro piezoelectric sensor chip.

[0092] The core innovation of this embodiment lies in combining the step-by-step symmetrical sensing unit structure with vacuum silicon-silicon bonding technology to construct an isolation structure of hollow cavity 1 without solid sound transmission path at the micrometer scale. This effectively suppresses acoustic crosstalk and simplifies the device structure, achieving high integration, good electrical isolation, and dynamic sound field control capabilities.

[0093] Through the above technical solution, the sensor chip achieves sound wave path isolation and dynamic control without the need for additional sound insulation structures, meeting the application requirements of miniaturization and high-density integration.

[0094] Please see Figure 1 The present invention also discloses a method for directional control of sound waves, the method comprising the following steps: S10: Target for controlling the received sound field; S20: Based on the sound field modulation target, determine the target operating mode of the ultrasonic micro piezoelectric sensor chip, and output the corresponding electrical signal parameters for driving the first top electrode 34 and the second top electrode 44 of the ultrasonic micro piezoelectric sensor chip; wherein, the electrical signal parameters include at least the phase and amplitude associated between the driving signals independently applied to the first top electrode 34 and the second top electrode 44. S30: Based on the electrical signal parameters, generate and apply corresponding driving signals to the first top electrode 34 and the second top electrode 44, so that the ultrasonic micro piezoelectric sensor chip generates a sound field that matches the sound field control target.

[0095] The purpose of receiving the sound field control target is to acquire the sound field characteristics desired by the user or system, such as the spatial distribution, intensity, direction, and focusing area of ​​the sound field. This target can be received through a human-machine interface, such as a user inputting desired sound field parameters on a graphical interface, or through preset program commands, or through real-time feedback data from other sensors or control systems.

[0096] Based on the sound field control target, the target operating mode of the ultrasonic micro piezoelectric sensor chip is determined, and the corresponding electrical signal parameters for driving the first top electrode 34 and the second top electrode 44 of the ultrasonic micro piezoelectric sensor chip are output. This step is the core decision-making link of sound field control.

[0097] The target operating mode refers to the overall operating state of the chip required to achieve the sound field control target, such as directional emission mode, projection sensing mode, or in-phase enhancement mode. The electrical signal parameters are the specific electrical quantities required to drive the first top electrode 34 and the second top electrode 44, which determine the chip's acoustic output. These parameters can be determined based on a pre-established lookup table that stores the mapping relationship between different sound field control targets and corresponding driving parameters; or through real-time calculation using acoustic models and optimization algorithms (e.g., beamforming algorithms, sound field synthesis algorithms) to dynamically calculate the required phase and amplitude parameters according to the sound field control target. The electrical signal parameters include at least the phase and amplitude associated with the driving signals independently applied to the first top electrode 34 and the second top electrode 44. Phase and amplitude are key parameters for controlling the acoustic output of the piezoelectric transducer. The phase and amplitude of the driving signals independently applied to the first top electrode 34 and the second top electrode 44 can precisely control the relative relationship of the sound waves excited by these two electrodes. By adjusting the relative phase of the driving signals from different electrodes, the interference and superposition of sound waves can be achieved, thereby changing the directionality of the sound field; by adjusting the amplitude of the driving signal, the magnitude of the local sound pressure level can be controlled. This independent yet correlated phase and amplitude control is the foundation for achieving complex sound field modulation.

[0098] Based on the electrical signal parameters, a corresponding driving signal is generated and applied to the first top electrode 34 and the second top electrode 44 so that the ultrasonic micro piezoelectric sensor chip generates a sound field that matches the sound field control target. This step is the process of converting the decision result into actual physical excitation.

[0099] The driving signals can be generated by a signal generator or a digital-to-analog converter (DAC), converting the determined electrical signal parameters into specific voltage or current waveforms. These driving signals are then amplified by a power amplifier and applied to the first top electrode 34 and the second top electrode 44 of the ultrasonic micro piezoelectric sensor chip. By precisely controlling the driving signals applied to each electrode, the piezoelectric layer of the chip will generate corresponding mechanical vibrations, thereby exciting sound waves. These sound waves superimpose in space to form a sound field consistent with the sound field control target.

[0100] The acoustic wave directional control method of this application achieves precise shaping of the sound field by systematically managing and controlling multiple independently controllable electrodes of an ultrasonic micro piezoelectric sensor chip. The method first receives an externally input sound field modulation target, which specifies the desired sound field characteristics. Then, based on this target, the system intelligently determines the target operating mode that the chip should adopt and calculates the electrical signal parameters required to drive the first top electrode 34 and the second top electrode 44. These parameters, especially the phase and amplitude of the driving signals independently applied to each electrode, are key to achieving fine sound field control. The first top electrode 34 and the second top electrode 44 of the ultrasonic micro piezoelectric sensor chip can be independently controlled, allowing them to function as independent sound source units. When corresponding driving signals are generated and applied to the first top electrode 34 and the second top electrode 44 according to the calculated electrical signal parameters, these two electrodes will respectively excite their corresponding piezoelectric layers to vibrate, thereby radiating sound waves outward. Since the phase and amplitude of the driving signals are precisely controlled, the sound waves generated by these two independent sound sources will undergo expected interference and superposition in space, thus forming a composite sound field that precisely matches the initial sound field modulation target. For example, the sound beam can be deflected by adjusting the relative phase of the two electrodes; the sound beam can be focused by adjusting their relative amplitude and combining it with the phase. This method fully utilizes the hardware advantage of independent control of multiple electrodes on the chip, transforming the abstract sound field control target into a specific electrical signal driving strategy. This enables flexible, precise, and dynamic control of the sound field output of the ultrasonic micro piezoelectric sensor chip, solving the problem of having only hardware structure but lacking a systematic control mechanism.

[0101] As a specific implementation method, the acoustic wave directional control method can be implemented as follows: First, the user inputs a sound field control target through a computer interface connected to the controller, for example, requesting the formation of a 2 mm diameter sound beam focus at a distance of 10 mm from the ultrasonic micro piezoelectric sensor chip. Upon receiving this target, the controller's built-in processor runs a preset sound field calculation algorithm. Based on the geometry and piezoelectric characteristics of the ultrasonic micro piezoelectric sensor chip, it calculates the driving signal parameters of the first top electrode 34 and the second top electrode 44 required to achieve the focusing target. These parameters include the frequency, amplitude A1, and phase φ1 of the driving signal applied to the first top electrode 34, and the frequency, amplitude A2, and phase φ2 of the driving signal applied to the second top electrode 44. The frequency is usually preset, while the amplitudes A1 and A2 and the phases φ1 and φ2 are dynamically calculated based on the focusing target. For example, to achieve focusing, the driving signals of the two electrodes may need to have a specific phase difference to ensure constructive interference at the focus. Subsequently, the controller of the ultrasonic micro piezoelectric sensor chip sends these calculated electrical signal parameters to a multi-channel arbitrary waveform generator. The waveform generator generates two independent drive waveforms based on the received parameters, and these waveforms are amplified by two independent power amplifiers. The amplified drive signals are then applied to the first top electrode 34 and the second top electrode 44 of the ultrasonic miniature piezoelectric sensor chip, respectively. Under the excitation of these precisely controlled electrical signals, the first and second sensing units of the chip will vibrate in sync, thereby forming a sound beam focus in space that conforms to the user's expectations.

[0102] Through the above technical solution, this application provides a systematic method for directional acoustic wave control, which can fully leverage the hardware advantages of independent multi-electrode control in ultrasonic miniature piezoelectric sensor chips. This method receives the acoustic field modulation target and intelligently determines the chip's operating mode and driving electrical signal parameters based on this target, particularly precisely controlling the phase and amplitude of the independent electrodes, thereby enabling the chip to generate an acoustic field highly matched to the target. This method transforms the ultrasonic miniature piezoelectric sensor chip from a simple acoustic wave transmitter into one that can dynamically and precisely shape and control the acoustic field according to actual application requirements, such as focusing, deflecting, scanning, or forming complex acoustic field patterns, greatly improving the chip's application flexibility and performance in fields such as ultrasonic imaging, therapy, and sensing.

[0103] In some embodiments described above in this application, a sound wave directional control method is proposed. This method can generate and apply a driving signal according to a preset sound field modulation target, thereby enabling the chip to generate a specific sound field. However, in practical applications, the sound field modulation target may not be constant. For example, in scenarios where continuous tracking of moving targets is required or a specific sound field distribution needs to be maintained in a dynamic environment, a single sound field generation process may not meet the requirements for real-time adaptability.

[0104] In response, this application further proposes S30: after generating and applying corresponding driving signals to the first top electrode 34 and the second top electrode 44 according to the electrical signal parameters, so that the ultrasonic micro piezoelectric sensor chip generates a sound field matching the sound field modulation target, the application further includes: S40: Based on the updated sound field control target, dynamically repeat the above steps to switch the operating mode of the ultrasonic micro piezoelectric sensor chip and the generated sound field.

[0105] "According to the updated sound field control target" refers to the system receiving a new, modified, or adjusted sound field control command. This updated sound field control target can originate from various sources, such as new commands input by the user through a human-computer interaction interface, data fed back from real-time monitoring of environmental changes by external sensors, or a next-stage target generated by preset program logic based on time or event triggers. "Dynamically repeating the above steps" means that after receiving the updated sound field control target, the system continuously re-executes the sound field control process described in claim 8. This includes re-determining the target operating mode of the ultrasonic micro piezoelectric sensor chip based on the new sound field control target, calculating the new electrical signal parameters (including phase and amplitude) required to drive the first top electrode 34 and the second top electrode 44, and then generating and applying the corresponding driving signal. This repetition can be continuous, periodic, or event-driven, i.e., triggered only when the sound field control target changes. "Switching the operating mode of the ultrasonic micro piezoelectric sensor chip and the generated sound field" means that by dynamically repeating the above steps, the ultrasonic micro piezoelectric sensor chip can change its operating state and the characteristics of the generated sound field in real time. For example, the chip can switch from generating a sound field focused on a specific point to generating a sound field across a scanning area, or from one sound wave frequency to another, thereby enabling flexible adjustment of the sound field direction, intensity, focus position, or mode.

[0106] The solution presented in this application addresses the adaptability issue when the sound field control target changes by introducing a dynamic repetition mechanism into the sound wave directional control method. Specifically, when the system receives an updated sound field control target, it does not remain in the original sound field state but immediately initiates an iterative process. During this process, the system re-evaluates the new sound field control target and, based on this, accurately calculates the electrical signal parameters required to drive the first top electrode 34 and the second top electrode 44. These parameters include at least the phase and amplitude associated between the driving signals independently applied to the first top electrode 34 and the second top electrode 44. Subsequently, the system generates and applies these new driving signals to the first top electrode 34 and the second top electrode 44. Since the first top electrode 34 and the second top electrode 44 can be controlled independently, and they are symmetrically arranged on the side facing away from the first and second piezoelectric layers, the chip can accurately adjust its vibration mode according to the new electrical signal parameters, thereby quickly and smoothly switching its operating mode and the generated sound field. This dynamic repetition mechanism, combined with the independent controllability of the first top electrode 34 and the second top electrode 44 in the chip structure, enables the ultrasonic micro piezoelectric sensor chip to respond in real time to changes in the external environment or application requirements, and achieve continuous adaptive control of the sound field.

[0107] The following is a concrete example to illustrate this. Assume the ultrasonic miniature piezoelectric sensor chip is used in a scenario requiring non-contact manipulation of a moving object. Initially, the system receives a sound field manipulation target, requesting the generation of a focused sound field at the initial position of object A. The control unit calculates the drive signal parameters for the first top electrode 34 and the second top electrode 44 based on this target and applies the drive signals, causing the chip to generate a sound field focused on object A. When object A begins to move, an external sensor (e.g., a vision sensor) detects the new position of object A in real time and sends this information to the control unit as an updated sound field manipulation target. Upon receiving the updated sound field manipulation target, the control unit immediately re-executes the sound field manipulation steps: it recalculates the new phase and amplitude parameters required to drive the first top electrode 34 and the second top electrode 44 based on the new position of object A. For example, if object A moves to the right, it may be necessary to adjust the phase difference between the first top electrode 34 and the second top electrode 44 so that the sound field focus also moves to the right. Subsequently, the control unit generates and applies these new drive signals to the first top electrode 34 and the second top electrode 44, thereby switching the operating mode of the ultrasonic micro piezoelectric sensor chip and the generated sound field, dynamically tracking and locking the sound field focus onto the moving object A. This process continues continuously, ensuring that the sound field remains matched to the moving target at all times.

[0108] Through the above technical solution, the ultrasonic miniature piezoelectric sensor chip can dynamically adjust its working mode and the generated sound field according to the constantly changing sound field control target. This enables the chip to exhibit high adaptability and flexibility in dynamic environments or applications requiring real-time interaction. For example, in applications requiring continuous tracking of moving targets, real-time focusing, or dynamic sound field scanning, this solution ensures that the sound field remains synchronized with changes in the target or environment, thereby significantly improving the functionality and application range of the ultrasonic miniature piezoelectric sensor chip and overcoming the limitations of traditional static sound field generation methods in dynamic scenarios.

[0109] The target operating modes described above include at least one of the following, but are not limited to: Mode 1: Apply driving signals of opposite phase to the first top electrode 34 and the second top electrode 44 to enable the ultrasonic micro piezoelectric sensor chip to emit directional sound waves; Mode 2: Apply a driving signal to the first top electrode 34 to make it a transmitter, and at the same time read the signal from the second top electrode 44 to make it a receiver, so as to realize the transmission of sound waves; Mode 3: Apply a driving signal with the same phase and amplitude to the first top electrode 34 and the second top electrode 44 to enhance the acoustic intensity on both sides of the ultrasonic micro piezoelectric sensor chip.

[0110] The core innovation of this embodiment lies in combining the electrical insulation and independent control characteristics of the first top electrode 34 and the second top electrode 44 with the dynamic adjustment of the phase and amplitude of the electrical signal, thereby achieving precise control of the sound wave emission direction, receiving function and sound intensity, and achieving the effects of eliminating acoustic crosstalk, improving directional performance and expanding functional diversity.

[0111] Specifically, this method is based on the structural characteristics that the first top electrode 34 and the second top electrode 44 are electrically insulated from each other and can be independently controlled. By dynamically adjusting the phase and amplitude relationship of the electrical signal applied to the electrodes, the ultrasonic micro piezoelectric sensor chip can flexibly switch working modes.

[0112] Mode 1 (Directional Launch Mode): Driving method: An alternating driving voltage (V1) is applied to the first top electrode 34, while an alternating driving voltage (V2 = -V1) with the same amplitude but opposite phase (180 degrees) is applied to the second top electrode 44. The first bottom electrode 32 and the second bottom electrode 42 on both sides are grounded as a common terminal.

[0113] Working Principle: Under this drive, the first piezoelectric layer 33 and the second piezoelectric layer 43 on both sides have opposite electric field directions. The first bottom electrode 32 and the second bottom electrode 42 are the same, but the applied voltages are opposite, causing the first vibrating diaphragm 31 and the second vibrating diaphragm 41 to vibrate in opposite directions. When one of the first vibrating diaphragm 31 and the second vibrating diaphragm 41 on one side vibrates outward (compressing the in front medium), the other of the first vibrating diaphragm 31 and the second vibrating diaphragm 41 on the other side vibrates inward (sparsening the in front medium). Due to the isolation of the hollow cavity 1, the sound waves on both sides propagate independently in their respective outer spaces. This mode can effectively ensure that the sound waves mainly propagate in one direction, while the sound waves on the other side are greatly suppressed due to destructive interference, which is particularly suitable for ultrasonic imaging or sonar that requires high directivity.

[0114] An AC drive signal with the same frequency but opposite phase is applied to the first top electrode 34 and the second top electrode 44. Since the two top electrodes are independently controllable and symmetrically arranged, this electrical signal causes the first piezoelectric layer 33 and the second piezoelectric layer 43 to deform in opposite directions, thereby driving the first diaphragm 31 and the second diaphragm 41 to vibrate with a 180-degree phase difference (i.e., one moves outward while the other moves inward). This anti-phase vibration generates a strong pressure difference within the hollow cavity 1, causing the sound wave energy to primarily superimpose and radiate in a specific direction outside the cavity, while radiation in the opposite direction is weakened due to interference, thus achieving efficient directional sound wave emission. This mode achieves good directivity without the need for external physical sound insulation structures. In other words, applying an anti-phase drive signal causes the two diaphragms to vibrate in opposite phases, forming a directional effect of sound wave phase cancellation and enhancement, thereby avoiding the complexity of traditional structures requiring additional sound insulation components. Mode 2 (Transmission Sensing Mode): Driving method: An alternating driving voltage (V1) is applied only to the first top electrode 34, causing it to vibrate as a transmitter. No voltage is applied to the second top electrode 44, but it is connected to a high input impedance readout circuit, acting as a receiver.

[0115] Working principle: The vibration of the first diaphragm 31 generates sound waves (S1). These sound waves are transmitted through the medium (which can be a vacuum, a specific gas, or a gel) of the hollow cavity 1 to the second diaphragm 41, causing it to vibrate passively. This vibration generates piezoelectric charges on the second piezoelectric layer 43, which are detected by the second top electrode 44, thereby transmitting the sound wave signal from one side to the other. This mode can be used for acoustic communication or signal relay in sound insulation structures.

[0116] A specific AC drive signal is applied to the first top electrode 34, causing it to act as a transmitter, driving the first diaphragm 31 to vibrate and generating sound waves within the hollow cavity 1. These sound waves propagate through the medium within the hollow cavity 1 to the second diaphragm 41. At this time, the second sensing unit 40 acts as a receiver; its second piezoelectric layer 43 generates an electrical signal due to the vibration of the second diaphragm 41, and reads this signal from the independently insulated second top electrode 44. By analyzing the relationship between the transmitted and received signals (such as amplitude attenuation and phase delay), the sensing and measurement of the medium characteristics within the hollow cavity 1 (such as pressure, density, and the presence of foreign objects) can be achieved, forming an integrated acoustic transmission or sensing channel.

[0117] The first top electrode 34 acts as a transmitter to drive the diaphragm, and the second top electrode 44 acts as a receiver to collect signals. The use of independent electrode control eliminates interference from solid-borne sound transmission paths, thus achieving efficient transmission of sound waves within a single device. Mode 3 (In-phase Enhancement Mode): Driving method: Apply alternating driving voltages of the same phase and amplitude to the first top electrode 34 and the second top electrode 44.

[0118] Working principle: Under this drive, the first diaphragm 31 and the second diaphragm 41 on both sides vibrate in the same direction. When they both vibrate outward, the sound waves on both sides are superimposed in phase, which enhances the sound intensity radiated on both sides of the chip, and the total radiated sound power is about twice that of single-sided operation. This mode is suitable for applications requiring high power output, such as ultrasonic cleaning, atomization, or long-distance detection.

[0119] A drive signal of the same phase and amplitude is applied to the first top electrode 34 and the second top electrode 44. This causes the first diaphragm 31 and the second diaphragm 41 to vibrate in complete synchronization. The two diaphragms move in the same direction, and the radiated sound waves are superimposed in phase in the space on both sides, thereby simultaneously obtaining enhanced sound pressure level and sound intensity on both sides of the chip. This mode is suitable for applications that require high-intensity ultrasonic emission from both sides simultaneously.

[0120] By dynamically switching the above modes via software or hardware switches, or by performing more complex programming control on the amplitude and phase of the signals applied to the two top electrodes (such as applying a specific phase shift to achieve beam deflection), the sound field can be dynamically adjusted, thereby achieving multi-functional operations such as sound beam scanning and focusing. This flexible control capability, combined with the chip's own dual-sided symmetrical integrated structure, allows the sensor chip to transcend the limitations of traditional single-sided structures with their single function, achieving excellent acoustic performance adjustment flexibility on the basis of miniaturized integration.

[0121] Applying a driving signal with the same phase and amplitude causes the two diaphragms to vibrate synchronously and generate a superposition effect of sound waves, significantly enhancing the sound intensity output. Due to this technical solution, the ultrasonic micro piezoelectric sensor chip achieves sound wave path isolation and dynamic sound field control at the micrometer scale, effectively overcoming the crosstalk, insufficient directivity, and functional limitations caused by the disordered radiation of sound waves to both sides in traditional single-sided structures. At the same time, it simplifies the device structure and improves integration.

[0122] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An ultrasonic miniature piezoelectric sensor chip, characterized in that, The ultrasonic miniature piezoelectric sensor chip includes: First substrate; The second substrate is arranged at a distance from the first substrate; A first sensing unit, comprising a first vibrating diaphragm, a first bottom electrode, a first piezoelectric layer, and a first top electrode stacked sequentially, wherein the two sides of the first vibrating diaphragm are respectively connected to the first substrate and the second substrate; and The second sensing unit includes a second vibrating diaphragm, a second bottom electrode, a second piezoelectric layer, and a second top electrode stacked sequentially. The two sides of the second vibrating diaphragm are respectively connected to the first substrate and the second substrate. The first substrate, the second substrate, the first vibrating diaphragm, and the second vibrating diaphragm together form a hollow cavity. The first bottom electrode is electrically connected to the second bottom electrode, the first top electrode and the second top electrode are electrically insulated from each other and can be controlled independently, and the side of the first top electrode facing away from the first piezoelectric layer and the side of the second top electrode facing away from the second piezoelectric layer are arranged symmetrically.

2. The ultrasonic micro piezoelectric sensor chip as described in claim 1, characterized in that, Both the first top electrode and the second top electrode include multiple electrode units, and the multiple electrode units are arranged at intervals so that each of the multiple electrode units can be controlled independently.

3. The ultrasonic micro piezoelectric sensor chip as described in claim 2, characterized in that, The number of electrode units is two, one of which is an inner circular electrode and the other is an outer ring electrode. The inner circular electrode is located inside the outer ring electrode and is spaced apart from the outer ring electrode.

4. The ultrasonic miniature piezoelectric sensor chip as described in claim 3, characterized in that, The outer ring electrode is also connected to a first connecting segment for connection to an external circuit; the outer ring electrode has a notch spaced apart from the first connecting segment, and the inner ring electrode is connected to a second connecting segment, which extends from the notch for connection to an external circuit.

5. The ultrasonic micro piezoelectric sensor chip as described in claim 1, characterized in that, The ultrasonic micro piezoelectric sensor chip also includes a bottom connection segment, which is fixed to one of the first substrate and the second substrate and is used to connect the first bottom electrode and the second bottom electrode.

6. The ultrasonic miniature piezoelectric sensor chip as described in claim 5, characterized in that, The ultrasonic micro piezoelectric sensor chip also includes two extension segments, which are respectively connected to the first bottom electrode and the second bottom electrode, and are also connected to the bottom connection segment. The two extension segments extend in opposite directions.

7. The ultrasonic miniature piezoelectric sensor chip as described in claim 5, characterized in that, The ultrasonic micro piezoelectric sensor chip also includes two top connection segments, which are respectively connected to the first top electrode and the second top electrode, and are fixed to the other of the first substrate and the second substrate; the two top connection segments extend in opposite directions.

8. The ultrasonic micro piezoelectric sensor chip as described in claim 1, characterized in that, The first and / or second diaphragm is made of polycrystalline silicon.

9. The ultrasonic micro piezoelectric sensor chip as described in claim 1, characterized in that, The hollow cavity is a vacuum cavity, or filled with inert gas or oxygen-adsorbing gel.

10. The ultrasonic micro piezoelectric sensor chip as described in claim 1, characterized in that, The first and / or second diaphragm are provided with one or more through holes.

11. A method for fabricating an ultrasonic micro piezoelectric sensor chip as described in any one of claims 1-10, characterized in that, The steps of the method for fabricating the ultrasonic micro piezoelectric sensor chip include: S1: Provide a first substrate and a second substrate; S2: A first oscillating film, a first bottom electrode, a first piezoelectric layer and a first top electrode are sequentially formed on the first substrate, and a second oscillating film, a second bottom electrode, a second piezoelectric layer and a second top electrode are sequentially formed on the second substrate; S3: Perform back cavity etching on the first substrate and the second substrate to form two cavities; S4: In a vacuum environment, the first substrate and the second substrate are bonded together using a silicon-silicon bonding process, so that the two cavities are connected to form a hollow cavity.

12. A method for directional control of acoustic waves, characterized in that, The acoustic wave directional control method includes the following steps: Target for receiving sound field modulation; Based on the sound field modulation target, the target operating mode of the ultrasonic micro piezoelectric sensor chip is determined, and the corresponding electrical signal parameters for driving the first top electrode and the second top electrode of the ultrasonic micro piezoelectric sensor chip are output; wherein, the electrical signal parameters include at least the phase and amplitude associated between the driving signals independently applied to the first top electrode and the second top electrode; Based on the electrical signal parameters, corresponding driving signals are generated and applied to the first and second top electrodes to enable the ultrasonic micro piezoelectric sensor chip to generate a sound field that matches the sound field modulation target.

13. The acoustic wave directional control method as described in claim 12, characterized in that, After generating and applying corresponding driving signals to the first and second top electrodes based on the electrical signal parameters, so that the ultrasonic micro piezoelectric sensor chip generates a sound field that matches the sound field modulation target, the method further includes: Based on the updated sound field control target, the above steps are dynamically repeated to switch the operating mode of the ultrasonic micro piezoelectric sensor chip and the generated sound field.

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