Ultrasonic transducer with multiple electrodes and multiple piezoelectric layers

Abstract

The present invention discloses an ultrasonic transducer having multiple electrodes and multiple piezoelectric layers. The transducer comprises a seven-layer structure arranged sequentially from top to bottom, wherein the first and fifth layers are pure electrode layers or composite electrode layers, the second, fourth, and sixth layers are pure piezoelectric layers, and the third and seventh layers are composite electrode layers or pure electrode layers, each comprising an electrode and an insulating gap. The transducer proposed in the present invention has extremely low power consumption, thereby reducing the power consumption of the transducer and increasing the ultrasonic output sound power of the transducer. It has great practical value in scenarios such as low-power and high-sound-power output applications, small-size applications, and high-frequency ultrasonic applications, further promoting innovation and implementation in the expansion of industrial and medical ultrasonic applications.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic transducers, and in particular to an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers. Background Art

[0002] Ultrasonic transducers are the core components for generating ultrasonic waves. They primarily utilize the inverse piezoelectric effect of piezoelectric materials to convert the electrical energy of the excitation signal into ultrasonic mechanical energy. Traditionally used transducer components are made of piezoelectric materials and are manufactured into various shapes through machining, grinding, heat treatment, polarization, and other processes. Electrode layers are applied on both sides of the piezoelectric material to form an electrode layer-piezoelectric layer-electrode layer structure. When an AC signal is applied to the two electrode layers for excitation, the thickness direction of the middle piezoelectric layer will stretch and contract due to the inverse piezoelectric effect of the piezoelectric material. This displacement change of stretching and contraction is the initial source of the ultrasonic wave. When there is a medium that can transmit ultrasonic waves around the transducer, ultrasonic waves will be emitted from the surface of the transducer.

[0003] Existing technologies have made innovative improvements based on the traditional electrode layer-piezoelectric layer-electrode layer transducer structure, achieving a multi-piezoelectric layer structure similar to electrode layer-piezoelectric layer-electrode layer-neutral layer-electrode layer-piezoelectric layer-electrode layer..., forming a microstructure transducer with multi-electrode and multi-piezoelectric layer excitation. Existing transducers have the following problems:

[0004] 1. The manufacturing process is complicated and the manufacturing cost is high;

[0005] 2. High power consumption and low output sound power;

[0006] 3. The modal vibration shape of the transducer is poor, which can easily lead to uneven spatial distribution of the sound field;

[0007] 4. The transducer has low resolution in lateral scanning in ultrasound imaging applications. Summary of the Invention

[0008] In response to the above-mentioned deficiencies in the prior art, the present invention provides an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers, which solves the problems of the existing transducer having a complex manufacturing process and high manufacturing cost, high power consumption, low output sound power, poor transducer modal vibration shape, and easily leading to uneven spatial distribution of the sound field and low resolution of the transducer in lateral scanning in ultrasonic imaging applications.

[0009] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers, the ultrasonic transducer includes a seven-layer structure arranged in sequence from top to bottom, the first layer structure and the fifth layer structure are pure electrode layers or composite electrode layers, the second layer structure, the fourth layer structure and the sixth layer structure are all pure piezoelectric layers, the third layer structure and the seventh layer structure are both composite electrode layers or pure electrode layers, and the composite electrode layer includes electrodes and insulating gaps.

[0010] The beneficial effects of the above solution are as follows: through the use of multi-electrode superposition excitation drive under the same amplitude excitation voltage, the maximum displacement amplitude of the transducer during ultrasonic emission is greatly enhanced, the transducer's acoustic output power is increased, and the transducer's power consumption is reduced. This solution also has better transducer modal vibration shapes, is less susceptible to the uncertainties of non-piezoelectric structure bending, and improves the spatial uniformity of the transmitted ultrasonic sound field.

[0011] Furthermore, both the pure electrode layer and the composite electrode layer are composed of electrodes, each electrode having the same properties and differing only in size; the pure piezoelectric layer is composed of piezoelectric films, each piezoelectric film having the same properties and differing only in size.

[0012] The beneficial effect of the above further scheme is: through the above technical scheme, a combination structure in which electrode layers and piezoelectric layers are alternately arranged is formed, so that the superposition of ultrasonic waves in each electrode area is realized, and the electrodes in the composite electrode layer are independent of each other. In the transducer drive control strategy, a single electrode excitation drive can be achieved, and a narrower ultrasonic beam can be emitted, and the width of the ultrasonic beam is determined by the width of a single electrode, which improves the resolution of the lateral scanning of the single ultrasonic transducer involved in the present invention in ultrasonic imaging applications.

[0013] Furthermore, the electrodes are made of conductive materials, and the piezoelectric film is made of materials having piezoelectric effect.

[0014] The beneficial effect of the above further scheme is that the electrodes made of conductive materials and the piezoelectric film made of piezoelectric effect materials are used to realize excitation after applying alternating current to the electrodes, and at the same time, the displacement amplitudes of the piezoelectric materials generated by the voltage amplitude on the electrodes are superimposed on each other.

[0015] Furthermore, the electrodes and insulating gaps in the composite electrode layer are arranged in sequence and spaced apart, and the sizes and numbers of the electrodes and insulating gaps are variable.

[0016] The beneficial effect of the above further solution is that the size and number of the electrodes and the insulating gaps can be changed according to actual conditions, which is conducive to expanding the scope of application of the structure described in this solution and improving the practicality of the structure.

[0017] Furthermore, the top view arrangement of the electrodes and the insulating gaps in the composite electrode layer includes a rectangular shape arranged sequentially from left to right, a ring shape arranged sequentially from inside to outside, or a square ring shape arranged sequentially from inside to outside.

[0018] The beneficial effect of the above further solution is that the top view structure of the electrodes and the insulating gap in the composite electrode layer is not unique and can be selected based on the actual usage scenario.

[0019] Furthermore, the device is driven by a multi-port differential signal method. Each electrode in the composite electrode layer corresponds to an independent differential signal port signal line. The electrical signals connected to adjacent electrodes have opposite polarities and are not connected in common. The electrodes in the pure electrode layer are connected to the common end of the electrical system.

[0020] The beneficial effect of the above further solution is that: through the above driving method, a multi-port differential signal method is adopted to realize the excitation driving operation of the ultrasonic transducer.

[0021] Furthermore, the device is driven by a multi-port single-ended signal method. Each electrode in the composite electrode layer corresponds to an independent single-ended signal port. The electrical signals connected to adjacent electrodes have the same polarity, and the electrodes are not connected in common. The electrodes in the pure electrode layer are connected to the common end of the electrical system.

[0022] The beneficial effect of the above further solution is that: through the above driving method, a multi-port single-ended signal method can also be adopted to realize the excitation driving work of the ultrasonic transducer.

[0023] Furthermore, the number of stacked structures of the ultrasonic transducer is variable according to actual conditions, and can be increased to more layers or decreased to fewer layers according to the structural sequence described in the present invention according to actual needs.

[0024] The beneficial effect of the above further solution is that: through the above technical solution, the number of stacking layers of the ultrasonic transducer can be increased or decreased according to actual needs, effectively expanding the scope of application of the present invention.

[0025] In addition, the present invention also adopts a technical solution: a method for manufacturing an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers, the manufacturing method comprising the following steps:

[0026] S1: depositing an etch stop layer on the substrate;

[0027] S2: performing multiple deposition and etching on the substrate after depositing a layer of etching stop layer to produce the required ultrasonic transducer structure including the substrate and the etching stop layer;

[0028] S3: The substrate and the etching stop layer in the ultrasonic transducer structure including the substrate and the etching stop layer are released and removed by etching to obtain an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers.

[0029] The beneficial effects of the above scheme are: the above technical scheme is used to manufacture the transducer structure proposed in the present invention, which facilitates large-scale production, simplifies the manufacturing process of the hollow cavity piezoelectric micromechanical ultrasonic transducer in the prior art, and reduces the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the first structural diagram of an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers.

[0031] Figure 2 This is the second structural diagram of an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers.

[0032] Figure 3 1 is a first cross-sectional structure of electrodes and insulating gaps in a composite electrode layer.

[0033] Figure 4 1 is a second cross-sectional structure of the electrodes and the insulating gap in the composite electrode layer.

[0034] Figure 5 1 is a third cross-sectional structure of electrodes and insulating gaps in the composite electrode layer.

[0035] Figure 6 The present invention is a flow chart of a method for manufacturing an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] Example 1, as Figure 1 As shown, an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers includes a seven-layer structure arranged in sequence from top to bottom, the first layer structure and the fifth layer structure are pure electrode layers, the second layer structure, the fourth layer structure and the sixth layer structure are pure piezoelectric layers, the third layer structure and the seventh layer structure are composite electrode layers, and the composite electrode layer includes electrodes and insulating gaps.

[0038] Example 2, as Figure 2 As shown, an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers includes a seven-layer structure arranged in sequence from top to bottom, the first layer structure and the fifth layer structure are both composite electrode layers, the second layer structure, the fourth layer structure and the sixth layer structure are all pure piezoelectric layers, the third layer structure and the seventh layer structure are both pure electrode layers, and the composite electrode layer includes electrodes and insulating gaps.

[0039] Both the pure electrode layer and the composite electrode layer are composed of electrodes, each electrode has the same properties and only differs in size. The pure piezoelectric layer is composed of piezoelectric films, each piezoelectric film has the same properties and only differs in size.

[0040] The electrodes are made of conductive materials, and the piezoelectric film is made of materials with piezoelectric effect.

[0041] The electrodes and insulating gaps in the composite electrode layer are arranged in sequence and spaced apart, and the sizes and numbers of the electrodes and insulating gaps are variable.

[0042] The top view of the arrangement of electrodes and insulating gaps in the composite electrode layer is a rectangular shape arranged from left to right, as shown in FIG. Figure 3 As shown, the ring shapes arranged from the inside to the outside are as follows: Figure 4 As shown, or square ring shapes arranged from the inside to the outside, such as Figure 5 shown.

[0043] The number of stacked structures in the device is variable according to actual conditions. The number of stacked structures is not limited to the seven layers described in this solution. It can be increased in more layers or decreased in fewer layers according to the structural sequence described in the present invention according to actual needs. The stacked structure in the figure is only used as a schematic diagram of the principle. The arrangement order is arranged in sequence according to the structure. For example, in Figure 1, from top to bottom, there are pure electrode layer, pure piezoelectric layer, composite electrode layer, pure piezoelectric layer, pure electrode layer, pure piezoelectric layer, composite electrode layer. According to this stacking relationship, you can continue to add pure piezoelectric layer, pure electrode layer, pure piezoelectric layer, composite electrode layer, etc. in sequence below the composite electrode layer, or you can reduce the number of layers in the same way.

[0044] The device is driven by a multi-port differential signaling scheme. Each electrode in the composite electrode layer corresponds to a separate differential signal port line. Adjacent electrodes receive signals of opposite polarity and are not connected in common. The electrodes in the pure electrode layer are connected to the common terminal of the electrical system. If the pure electrode layer is fabricated into a composite electrode layer, all electrodes in the composite electrode layer are still connected to the common terminal of the electrical system. The connection method for each electrode in the composite electrode layer follows the same rules. When the composite electrode layer has more electrodes and the structure shown in the figure has more stacked structures, the operating principle is still implemented according to this scheme.

[0045] The device can also be driven using a multi-port single-ended signaling scheme. Each electrode in the composite electrode layer corresponds to an independent single-ended signal port. Adjacent electrodes receive electrical signals of the same polarity and are not connected in common. The electrodes in the pure electrode layer are connected to the common terminal of the electrical system. If the pure electrode layer is fabricated as a composite electrode layer, all electrodes in the composite electrode layer are still connected to the common terminal of the electrical system. The connection method for each electrode in the composite electrode layer follows the same rules. Similarly, when there are more electrodes in the composite electrode layer and more stacked structures in the structure shown in the diagram of the invention, the operating principle is still implemented according to this scheme.

[0046] In one embodiment of the present invention, based on the transducer with a multi-electrode and multi-piezoelectric layer structure in the prior art, the electrode layer of each layer is divided into multiple electrodes, so that the area of each electrode forms a certain proportional relationship with each other, which is conducive to the precise control of the excitation electrical signal. Adjacent electrodes are electrically isolated, which facilitates the more subdivided multi-level excitation driving of the piezoelectric layer, and truly achieves the reduction of transducer power consumption and the improvement of the ultrasonic output sound power of the transducer. The maximum displacement amplitude of the multi-electrode and multi-piezoelectric layer ultrasonic transducer described in this solution when emitting sound waves is determined by the displacement amplitude generated by the voltage amplitude on the electrode in the composite electrode layer, the number of electrodes in the composite electrode layer, and the number of piezoelectric layers. The relationship between the four follows the following calculation formula:

[0047] Maximum displacement amplitude = (displacement amplitude generated by the voltage amplitude on the electrode * number of electrodes) * number of piezoelectric layers

[0048] It can be clearly seen from the above calculation formula that in order to achieve a larger displacement amplitude when the transducer emits ultrasonic waves, the number of electrodes and piezoelectric layers can be increased on the basis of using a low voltage amplitude on the electrodes in the composite electrode layer, truly realizing the two most prominent core advantages brought by the present invention: low power consumption drive and high sound power output (determined by the maximum displacement amplitude when the transducer emits ultrasonic waves).

[0049] Example 3, as Figure 6 As shown, a method for manufacturing an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers comprises the following steps:

[0050] S1: depositing an etch stop layer on the substrate;

[0051] S2: performing multiple deposition and etching on the substrate after depositing a layer of etching stop layer to produce the required ultrasonic transducer structure including the substrate and the etching stop layer;

[0052] S3: The substrate and the etching stop layer in the ultrasonic transducer structure including the substrate and the etching stop layer are released and removed by etching to obtain an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers.

[0053] The manufacturing process steps involved in the present invention are simple, and only deposition and etching processes are required to realize the processing and manufacturing of the entire device. No other complex process flows are involved in the process, which greatly simplifies the manufacturing process of piezoelectric micromechanical ultrasonic transducers in the prior art and effectively reduces the manufacturing cost of transducer products. The electrodes in the composite electrode layer of this scheme are independent of each other. In the transducer drive control strategy, a single electrode excitation drive can be achieved, and a narrower ultrasonic beam can be emitted. The width of the ultrasonic beam is determined by the width of a single electrode, which improves the resolution of the lateral scanning of the single ultrasonic transducer involved in the present invention in ultrasonic imaging applications. This cannot be achieved with traditional ultrasonic transducers and prior art ultrasonic transducers. The maximum displacement amplitude of the multi-electrode and multi-piezoelectric layer ultrasonic transducer involved in the present invention when emitting ultrasonic waves is generated by the voltage amplitude on the electrodes in the composite electrode layer. The displacement amplitude, the number of electrodes in the composite electrode layer, and the number of piezoelectric layers are jointly determined. On the basis of using a low voltage amplitude on the electrodes in the composite electrode layer, the number of electrodes and the number of piezoelectric layers can be increased to truly achieve low-power drive. The transducer involved in this invention has extremely low power consumption, realizing energy-saving application of ultrasound. At the same time, the ultrasonic transducer in the present invention adopts multi-electrode superposition excitation drive under the same amplitude excitation voltage, which greatly enhances the maximum displacement amplitude of the transducer when emitting ultrasonic waves and improves the acoustic output power of the transducer. In addition, the modal vibration shape of the multi-electrode multi-piezoelectric layer ultrasonic transducer involved in the present invention is completely determined by the piezoelectric layer, and is no longer determined by the bending of non-piezoelectric structures such as the neutral layer in the prior art to determine the modal vibration shape of the transducer. Therefore, it has a better transducer modal vibration shape, is not easily affected by the uncertainty of the bending of the non-piezoelectric structure, and truly improves the uniformity of the spatial distribution of the emitted ultrasonic sound field.

[0054] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the invention.

Claims

1. An ultrasonic transducer with multiple electrodes and multiple piezoelectric layers, characterized in that: The ultrasonic transducer comprises a seven-layer structure arranged sequentially from top to bottom, wherein the first and fifth layers are pure electrode layers or composite electrode layers, the second, fourth and sixth layers are pure piezoelectric layers, and the third and seventh layers are composite electrode layers or pure electrode layers, wherein the composite electrode layer comprises electrodes and insulating gaps; The pure electrode layer and the composite electrode layer are both composed of electrodes, each of which has the same properties and differs only in size; the pure piezoelectric layer is composed of piezoelectric films, each of which has the same properties and differs only in size; The electrodes and insulating gaps in the composite electrode layer are arranged in a rectangular shape from left to right, in a ring shape from inside to outside, or in a square ring shape from inside to outside when viewed from above; The maximum displacement amplitude of the ultrasonic transducer when emitting sound waves is determined by the displacement amplitude generated by the voltage amplitude on the electrodes in the composite electrode layer, the number of electrodes in the composite electrode layer, and the number of piezoelectric layers. The relationship between the four follows the following calculation formula: Maximum displacement amplitude = (displacement amplitude generated by the voltage amplitude on the electrode × number of electrodes) × number of piezoelectric layers; The ultrasonic transducer is driven by a multi-port differential signal mode and a multi-port single-ended signal mode; If the ultrasonic transducer is driven by a multi-port differential signal mode, each electrode in the composite electrode layer corresponds to an independent differential signal port signal line, the electrical signals connected to adjacent electrodes have opposite polarities, and the electrodes are not connected in common, and the electrodes in the pure electrode layer are connected to the common end of the electrical system; If the ultrasonic transducer is driven by a multi-port single-ended signal mode, each electrode in the composite electrode layer corresponds to an independent single-ended signal port, the electrical signals connected to adjacent electrodes have the same polarity, and the electrodes are not connected in common, and the electrodes in the pure electrode layer are connected to the common end of the electrical system.

2. The ultrasonic transducer with multiple electrodes and multiple piezoelectric layers according to claim 1, characterized in that: The electrodes are made of conductive materials, and the piezoelectric film is made of materials having piezoelectric effect.

3. The ultrasonic transducer with multiple electrodes and multiple piezoelectric layers according to claim 1, characterized in that: The electrodes and insulating gaps in the composite electrode layer are arranged in sequence and spaced apart, and the sizes and numbers of the electrodes and insulating gaps are variable.

4. The ultrasonic transducer with multiple electrodes and multiple piezoelectric layers according to claim 1, characterized in that: The number of stacked structures of the ultrasonic transducer is variable according to actual conditions, and can be increased to more layers or decreased to fewer layers according to the structural sequence described in the present invention according to actual needs.

5. A method for manufacturing an ultrasonic transducer having multiple electrodes and multiple piezoelectric layers according to any one of claims 1 to 4, characterized in that: The production method comprises the following steps: S1: depositing an etch stop layer on the substrate; S2: performing multiple deposition and etching on the substrate after depositing a layer of etching stop layer to produce the required ultrasonic transducer structure including the substrate and the etching stop layer; S3: The substrate and the etching stop layer in the ultrasonic transducer structure including the substrate and the etching stop layer are released and removed by etching to obtain an ultrasonic transducer with multiple electrodes and multiple piezoelectric layers.

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