High-sensitivity deepwater micro-electro-mechanical hydrophone

Abstract

The invention provides a high-sensitivity deepwater micro-electro-mechanical hydrophone, belongs to the field of underwater acoustic transducers, and solves the problem that an existing hydrophone cannot give consideration to sensitivity and deepwater work at the same time. The sensor comprises a sensitive chip, a silicon backing layer and a gas-liquid balance module, in the sensitive chip, an upper molybdenum electrode layer, a piezoelectric aluminum nitride film and a lower molybdenum electrode layer are sequentially located in an upper insulating layer, and a silicon device layer is located between the upper insulating layer and a lower insulating layer; the silicon backing layer is fixedly connected with the lower insulating layer, a backing liquid cavity and a micro-connection channel are arranged in the silicon backing layer, and the micro-connection channel is communicated with the backing liquid cavity; the gas-liquid balance module is fixedly connected to the silicon backing layer, a gas-liquid balance micro-channel is arranged in the gas-liquid balance module, the gas-liquid balance micro-channel is filled with liquid, one end of the gas-liquid balance micro-channel is communicated with the micro-connection channel, the gas-liquid balance module is provided with an elastic sealing layer, and the elastic sealing layer is arranged on the silicon backing layer. The elastic sealing layer is used for sealing the other end of the gas-liquid balance microchannel. The pressure-resistant performance can be improved, and the sensitivity is not degraded.

Description

Technical Field

[0001] This invention belongs to the field of underwater acoustic transducer technology, and in particular relates to a high-sensitivity deep-sea microelectromechanical hydrophone. Background Technology

[0002] To explore the deep sea, humans must develop deep-sea sonar equipment. Hydrophones, as the "window" through which sonar systems interact and exchange information with the water medium, directly impact the effectiveness of the sonar system. Traditional hydrophones suffer from drawbacks such as difficulties in miniaturization and integration, and high energy consumption. Combining the advantages of micromachining (MEMS) technology is an effective way to solve the bottleneck problems of traditional hydrophones. Piezoelectric MEMS hydrophones have advantages such as high sound pressure sensitivity and low power consumption. However, as the diving depth of the sonar platform increases, the hydrostatic pressure rises at a rate of 10 MPa / km, which significantly affects the sensitivity and structural pressure resistance of the hydrophone. Filling the back cavity of the MEMS sensitive chip with liquid can achieve pressure balance inside and outside the radiating surface, thereby increasing the operating depth; however, the liquid cavity load will lead to a significant decrease in the sensitivity of the MEMS hydrophone. Existing MEMS hydrophones cannot balance sensitivity and deep-sea operation, and cannot meet the requirements for high-sensitivity MEMS hydrophones in deep-sea transducers. Summary of the Invention

[0003] In view of this, in order to solve the problem that existing MEMS hydrophones cannot balance sensitivity and deep-water operation, and cannot meet the requirements of high-sensitivity MEMS hydrophones for deep-water transducers, this invention proposes a high-sensitivity deep-water MEMS hydrophone.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A high-sensitivity deep-sea microelectromechanical hydrophone includes: The sensitive chip includes an upper insulating layer, a lower insulating layer, an upper molybdenum electrode layer, a lower molybdenum electrode layer, a piezoelectric aluminum nitride thin film, and a silicon device layer. The upper molybdenum electrode layer, the lower molybdenum electrode layer, and the piezoelectric aluminum nitride thin film are all located within the upper insulating layer. The piezoelectric aluminum nitride thin film is located between the upper molybdenum electrode layer and the lower molybdenum electrode layer, and the silicon device layer is located between the upper insulating layer and the lower insulating layer. A silicon backing layer is fixedly connected to the lower insulating layer. The silicon backing layer has a backing liquid cavity and a micro-connection channel, and the micro-connection channel is connected to the backing liquid cavity. The gas-liquid balance module is fixedly connected to the silicon backing layer. The gas-liquid balance module has a gas-liquid balance microchannel filled with liquid. One end of the gas-liquid balance microchannel is connected to the micro-connection channel. The gas-liquid balance module has an elastic sealing layer for sealing the other end of the gas-liquid balance microchannel.

[0005] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, the gas-liquid balance microchannel is spiral-shaped.

[0006] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, the gas-liquid balance module is made of organic materials, metals, or ceramic materials.

[0007] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, the elastic sealing layer is made of rubber material.

[0008] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, the silicon device layer is made of monocrystalline silicon material.

[0009] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, both the upper and lower insulating layers are made of silicon dioxide material.

[0010] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, the liquid used is water, silicone oil, or castor oil.

[0011] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, the piezoelectric aluminum nitride thin film is fabricated using alloy Al / Sc target sputtering technology.

[0012] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, the backing liquid cavity is etched using the Bosch deep silicon dry etching process.

[0013] As a preferred embodiment of the aforementioned high-sensitivity deep-sea microelectromechanical hydrophone, the gas-liquid balance module is manufactured using 3D printing technology.

[0014] Compared with the prior art, the beneficial effects of the high-sensitivity deep-sea microelectromechanical hydrophone provided by the present invention are: This invention provides a high-sensitivity deep-sea microelectromechanical hydrophone. This high-sensitivity deep-sea microelectromechanical hydrophone improves pressure resistance while maintaining sensitivity. The upper and lower surfaces of the piezoelectric aluminum nitride film are respectively an upper molybdenum electrode layer and a lower molybdenum electrode layer. The upper and lower molybdenum electrode layers and the piezoelectric aluminum nitride film are all located within an upper insulating layer, and a silicon device layer is located between the upper and lower insulating layers. A silicon backing layer is fixedly connected to the lower insulating layer. A backing cavity is etched into the silicon backing layer to form a backing liquid cavity, which is filled with compressed air. Simultaneously, a micro-connection channel communicating with the backing liquid cavity is etched into the silicon backing layer. A gas-liquid balance module is fixedly connected to the silicon backing layer. One end of the gas-liquid balance microchannel within the gas-liquid balance module is connected to the micro-connection channel, and the other end is sealed by an elastic sealing layer. Liquid is filled within a gas-liquid balance microchannel. When the MEMS deep-water hydrophone operates at the target water depth, the external water medium pushes the elastic sealing layer inward, compressing the liquid within the gas-liquid balance microchannel. The liquid then enters the micro-connecting channel, ensuring the gas-liquid interface remains within the micro-connecting channel and preventing liquid from entering the backing liquid cavity. The acoustic impedance characteristics generated by the viscosity of the liquid within the micro-connecting channel and the gas-liquid balance microchannel, combined with the acoustic capacitance characteristics of the backing liquid cavity, constitute an RC low-pass filter, significantly improving the low-frequency sensitivity of the MEMS hydrophone. Simultaneously, the gas-liquid interface balancing strategy suppresses the degrading effect of liquid load on the vector hydrophone's sensitivity, greatly enhancing the acoustic transmission gain. This high-sensitivity deep-water MEMS hydrophone also improves pressure resistance. Existing MEMS hydrophones, due to their low structural strength, typically operate at depths of a few meters, with few deep-water MEMS hydrophones available. This high-sensitivity deep-sea microelectromechanical hydrophone can achieve both structural pressure resistance and the suppression of sensitivity degradation. If the space of the hydrophone's structural housing is sufficient, the volume of the gas-liquid balance microchannel will be adequate, potentially enabling a working water depth of over 2000 meters. Attached Figure Description

[0015] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of a high-sensitivity deep-sea microelectromechanical hydrophone provided in a specific embodiment of the present invention; Figure 2 This is a diagram showing the acoustic impedance characteristics of the liquid within the gas-liquid balance microchannel and microconnection channel of the high-sensitivity deep-sea microelectromechanical hydrophone provided in a specific embodiment of the present invention.

[0016] Figure 3 This is a diagram showing the acoustic transmission gain curve of the RC low-pass filter of the high-sensitivity deep-sea microelectromechanical hydrophone provided in a specific embodiment of the present invention. Figure 4This is a sensitivity curve of a microelectromechanical hydrophone (the three lines in the figure represent the high-sensitivity deep-water microelectromechanical hydrophone, the hydrophone with a liquid-filled backing cavity, and the hydrophone with a gas-filled backing cavity in this embodiment, respectively).

[0017] In the picture: 1. Upper insulating layer; 2. Silicon device layer; 3. Lower insulating layer; 4. Upper molybdenum electrode layer; 5. Piezoelectric aluminum nitride film; 6. Lower molybdenum electrode layer; 7. Silicon backing layer; 8. Backing liquid cavity; 9. Micro-connection channel; 10. Gas-liquid balance module; 11. Gas-liquid balance microchannel; 12. Elastic sealing layer. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0019] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0021] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0022] See Figure 1-4 This invention provides a high-sensitivity deep-sea microelectromechanical hydrophone, comprising a sensitive chip, a silicon backing layer 7, and a gas-liquid balance module 10. The sensitive chip includes an upper insulating layer 1, a lower insulating layer 3, an upper molybdenum electrode layer 4, a lower molybdenum electrode layer 6, a piezoelectric aluminum nitride film 5, and a silicon device layer 2. The upper molybdenum electrode layer 4, the lower molybdenum electrode layer 6, and the piezoelectric aluminum nitride film 5 are all located within the upper insulating layer 1. The piezoelectric aluminum nitride film 5 is located between the upper molybdenum electrode layer 4 and the lower molybdenum electrode layer 6. The silicon device layer 2 is located between the upper insulating layer 1 and the lower insulating layer 6. Between the insulating layers 3; the silicon backing layer 7 is fixedly connected to the lower insulating layer 3, and the silicon backing layer 7 is provided with a backing liquid cavity 8 and a micro-connection channel 9, which are connected to the backing liquid cavity 8; the gas-liquid balance module 10 is fixedly connected to the silicon backing layer 7, and the gas-liquid balance module 10 is provided with a gas-liquid balance microchannel 11, which is filled with liquid. One end of the gas-liquid balance microchannel 11 is connected to the micro-connection channel 9, and the gas-liquid balance module 10 is provided with an elastic sealing layer 12, which is used to seal the other end of the gas-liquid balance microchannel 11.

[0023] This high-sensitivity deep-sea microelectromechanical hydrophone improves pressure resistance while maintaining sensitivity. The upper and lower surfaces of the piezoelectric aluminum nitride film 5 are respectively the upper molybdenum electrode layer 4 and the lower molybdenum electrode layer 6. The upper molybdenum electrode layer 4, the lower molybdenum electrode layer 6, and the piezoelectric aluminum nitride film 5 are all located within the upper insulating layer 1, and the silicon device layer 2 is located between the upper insulating layer 1 and the lower insulating layer 3. The silicon backing layer 7 is fixedly connected to the lower insulating layer 3. The silicon backing layer 7 is etched with a backing cavity to form a backing liquid cavity 8, which is filled with compressed air. Simultaneously, a micro-connection channel 9 communicating with the backing liquid cavity 8 is etched on the silicon backing layer 7. The gas-liquid balance module 10 is fixedly connected to the silicon backing layer 7. One end of the gas-liquid balance microchannel 11 within the gas-liquid balance module 10 communicates with the micro-connection channel 9, and the other end is sealed by an elastic sealing layer 12. Liquid is filled into the gas-liquid balance microchannel 11. When the MEMS deep-water hydrophone operates at the target water depth, the external water medium pushes the elastic sealing layer 12 to deform inward, squeezing the liquid inside the gas-liquid balance microchannel 11. The liquid inside the gas-liquid balance microchannel 11 enters the micro-connection channel 9, ensuring that the gas-liquid interface remains within the micro-connection channel 9 and the liquid does not enter the backing liquid cavity 8. The acoustic impedance characteristics are generated by the viscosity of the liquid in the micro-connection channel 9 and the gas-liquid balance microchannel 11, and the backing liquid cavity 8 has acoustic capacitance characteristics. Together, they form an RC low-pass filter, which can significantly improve the low-frequency sensitivity of the MEMS hydrophone. At the same time, the gas-liquid interface balancing strategy suppresses the degrading effect of liquid load on the sensitivity of the vector hydrophone, significantly improving the sensitivity and acoustic transmission gain. This high-sensitivity deep-water MEMS hydrophone can also improve pressure resistance. Existing MEMS hydrophones are usually used in water depths of a few meters due to their low structural strength, and there are few MEMS hydrophones for deep water. This high-sensitivity deep-sea microelectromechanical hydrophone can achieve structural pressure resistance and suppress sensitivity degradation. If the space of the hydrophone's structural housing is sufficient, the volume of the gas-liquid balance microchannel 11 will be sufficient, and it is expected to achieve a working water depth of more than 2,000 meters.

[0024] A piezoelectric aluminum nitride thin film 5 was fabricated using alloy Al / Sc target sputtering technology. The backing liquid cavity 8 of the high-depth sensitive chip was etched using Bosch deep silicon dry etching technology. Then, a gas-liquid balance module 10 with gas-liquid balance microchannels 11, 3D-printed, was bonded to and encapsulated with the hydrophone's sensitive chip. According to the gas balance equation... Where V0 is the volume of the backing liquid cavity 8, P0 is the initial liquid pressure inside the backing liquid cavity 8, typically one atmosphere (0.1 MPa). γ is the specific heat coefficient, P is the liquid pressure after the backing liquid cavity 8 is compressed, and V is the sum of the volumes of the backing liquid cavity 8 and the micro-connecting channel 9. The volume of the micro-connecting channel 9 is determined based on the hydrostatic pressure corresponding to the target depth. For example, a water depth of 1000 meters corresponds to 100 atmospheres, so the volume of the micro-connecting channel 9 must be greater than 99 times V0 to ensure that the backing liquid cavity 8 is filled with compressed air without liquid entering. At this point, the internal and external pressures of the upper and lower surfaces of the piezoelectric aluminum nitride film 5 are balanced, and its structure will not be damaged.

[0025] In this embodiment, the gas-liquid balance microchannel 11 is spiral-shaped. Within the limited volume space of the gas-liquid balance module 10, the length of the gas-liquid balance microchannel 11 can be increased, i.e., its volume can be increased. To ensure that the sum V of the volumes of the backing liquid cavity 8, the micro-connecting channel 9, and the gas-liquid balance microchannel 11 is greater than 99 times the volume V0 of the backing liquid cavity 8, the length of the gas-liquid balance microchannel 11 must be increased. The gas-liquid balance microchannel 11 can also be in other shapes that increase its length; a spiral shape is not the only option.

[0026] In this embodiment, the gas-liquid balance module 10 is made of organic materials, metals, or ceramic materials.

[0027] In this embodiment, the elastic sealing layer 12 is made of rubber material.

[0028] In this embodiment, the silicon device layer 2 is made of single-crystal silicon material.

[0029] In this embodiment, both the upper insulating layer 1 and the lower insulating layer 3 are made of silicon dioxide.

[0030] In this embodiment, the liquid is water, silicone oil, or castor oil.

[0031] Obviously, the above-disclosed embodiments of the present invention are merely illustrative of the invention. The embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. It is neither necessary nor possible to exhaustively describe all embodiments herein.

Claims

1. A high-sensitivity deep-sea microelectromechanical hydrophone, characterized in that, include: The sensitive chip includes an upper insulating layer (1), a lower insulating layer (3), an upper molybdenum electrode layer (4), a lower molybdenum electrode layer (6), a piezoelectric aluminum nitride film (5), and a silicon device layer (2). The upper molybdenum electrode layer (4), the lower molybdenum electrode layer (6), and the piezoelectric aluminum nitride film (5) are all located within the upper insulating layer (1). The piezoelectric aluminum nitride film (5) is located between the upper molybdenum electrode layer (4) and the lower molybdenum electrode layer (6). The silicon device layer (2) is located between the upper insulating layer (1) and the lower insulating layer (3). Silicon backing layer (7), silicon backing layer (7) is fixedly connected to the lower insulating layer (3), and the silicon backing layer (7) is provided with a backing liquid cavity (8) and a micro-connection channel (9), and the micro-connection channel (9) is connected to the backing liquid cavity (8). A gas-liquid balance module (10) is fixedly connected to a silicon backing layer (7). A gas-liquid balance microchannel (11) is provided inside the gas-liquid balance module (10). The gas-liquid balance microchannel (11) is filled with liquid. One end of the gas-liquid balance microchannel (11) is connected to a micro-connection channel (9). The gas-liquid balance module (10) is provided with an elastic sealing layer (12). The elastic sealing layer (12) is used to seal the other end of the gas-liquid balance microchannel (11).

2. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: The gas-liquid balance microchannel (11) is spiral-shaped.

3. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: The gas-liquid balance module (10) is made of organic materials, metals or ceramic materials.

4. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: The elastic sealing layer (12) is made of rubber material.

5. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: The silicon device layer (2) is made of single-crystal silicon material.

6. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: Both the upper insulating layer (1) and the lower insulating layer (3) are made of silicon dioxide.

7. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: The liquid is water, silicone oil, or castor oil.

8. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: The piezoelectric aluminum nitride thin film (5) is fabricated using alloy Al / Sc target sputtering technology.

9. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: The backing liquid cavity was etched using the Bosch deep silicon dry etching process (8).

10. The high-sensitivity deep-sea microelectromechanical hydrophone according to claim 1, characterized in that: The gas-liquid balance module (10) is manufactured using 3D printing technology.

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