CN112620057B - Ultrasonic transducer and parameter configuration method thereof - Google Patents
Ultrasonic transducer and parameter configuration method thereof Download PDFInfo
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- CN112620057B CN112620057B CN201910907186.1A CN201910907186A CN112620057B CN 112620057 B CN112620057 B CN 112620057B CN 201910907186 A CN201910907186 A CN 201910907186A CN 112620057 B CN112620057 B CN 112620057B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/0292—Electrostatic transducers, e.g. electret-type
Abstract
The application discloses an ultrasonic transducer and a parameter configuration method thereof, wherein the parameter configuration method of the ultrasonic transducer comprises the following steps: providing an ultrasound transducer, said ultrasound transducer comprising: an upper electrode, a vibrating diaphragm, an insulating layer and a substrate; applying a preset voltage on the substrate, and tunneling charges of the substrate to the insulating layer under the action of the preset voltage, so that a preset number of charges are stored in the insulating layer, and the preset number of charges are used for configuring the bandwidth fraction of the ultrasonic transducer to be increased to a preset bandwidth fraction and configuring the resonance frequency of the ultrasonic transducer to be a preset frequency. The ultrasonic transducer regulates and controls the resonance frequency through an electrical method, and improves the bandwidth fraction by using charge tunneling.
Description
Technical Field
The application relates to the technical field of ultrasound, in particular to an ultrasonic transducer and a parameter configuration method thereof.
Background
With the continuous development of science and technology, ultrasonic transducers are gradually applied to a plurality of fields, and the ultrasonic transducer technology is a core technology in the field of medical imaging.
The bandwidth of an ultrasonic transducer is an important factor influencing the transmission efficiency and the receiving resolution, the transducer is limited in ultrasonic application due to the problem of low bandwidth, and at present, the matching layer technology is an effective method for widening the bandwidth of the transducer, but the process is complex, the capacitive ultrasonic transducer (CMUT) has higher bandwidth, but has the problem in low-frequency application that thinning and lengthening are needed to reduce the rigidity and obtain low resonance frequency. The design of the ultrasonic transducer depends on the physical structure size, the frequency needs to be reduced by changing the physical structure size in low-frequency application, and the central frequency needs to be improved by adopting a small size by changing the physical structure size in high-frequency application, so that the problem of overlarge rigidity and low sensitivity is brought.
Disclosure of Invention
The application provides an ultrasonic transducer and a parameter configuration method thereof, wherein the ultrasonic transducer adjusts and controls resonance frequency through an electrical method and obtains a large bandwidth fraction by using charge tunneling.
A first aspect of the present application provides an ultrasonic transducer comprising: the substrate is doped with a preset substance to form a lower electrode with a conductive characteristic, and the insulating layer is made of a preset material with charge storage capacity;
the upper electrode is arranged on the outer surface of the vibrating diaphragm, the insulating layer is arranged relative to the inner surface of the vibrating diaphragm, a cavity is formed between the vibrating diaphragm and the insulating layer, the insulating layer is arranged on the first surface of the substrate, and the first surface is the surface, close to the vibrating diaphragm, of the substrate;
the substrate is used for tunneling charges of the substrate to the insulating layer under the action of a preset voltage, so that the insulating layer stores a preset number of charges; the preset number of charges is used for configuring the bandwidth fraction of the ultrasonic transducer to be increased to a preset bandwidth fraction and configuring the frequency of the ultrasonic transducer to be a preset frequency.
With reference to the first aspect of the present application, in one possible implementation manner of the first aspect of the present application, the insulating layer structure includes any one of:
a single-layer insulating layer;
and a first sub-insulating layer and a second sub-insulating layer which are stacked.
In one possible embodiment, the structure of the insulating layer includes a first sub-insulating layer and a second sub-insulating layer which are stacked; in the stacked first and second sub-insulating layers, the first sub-insulating layer is a charge trapping layer, the second sub-insulating layer is a charge tunneling layer, and the second sub-insulating layer is disposed between the first sub-insulating layer and the substrate.
In one possible embodiment, the insulating layer has a thickness of 16-55 nm.
In one possible embodiment, the predetermined material includes any one of: silicon oxynitride, polysilicon.
In one possible embodiment, the predetermined substance comprises: aluminum.
In a possible implementation, the relationship between the preset number of charges and the bandwidth fraction of the ultrasonic transducer is a direct proportional relationship, and the relationship between the number of charges stored by the insulating layer and the resonance frequency of the ultrasonic transducer is an inverse proportional relationship.
A second aspect of the present application provides a method of configuring parameters of an ultrasound transducer, the method comprising:
providing an ultrasound transducer, said ultrasound transducer comprising: the substrate is doped with a preset substance to form a lower electrode with a conductive characteristic, and the insulating layer is made of a preset material with charge storage capacity;
the upper electrode is arranged on the outer surface of the vibrating diaphragm, the insulating layer is arranged relative to the inner surface of the vibrating diaphragm, a cavity is formed between the vibrating diaphragm and the insulating layer, the insulating layer is arranged on the first surface of the substrate, and the first surface is the surface, close to the vibrating diaphragm, of the substrate;
applying a preset voltage on the substrate, and tunneling charges of the substrate to the insulating layer under the action of the preset voltage, so that a preset number of charges are stored in the insulating layer, and the preset number of charges are used for configuring the bandwidth fraction of the ultrasonic transducer to be increased to a preset bandwidth fraction and configuring the resonance frequency of the ultrasonic transducer to be a preset frequency.
In combination with the second aspect of the present application, in one possible implementation, the method further includes:
adjusting the preset voltage to adjust the amount of charges stored by the insulating layer so that the bandwidth fraction and the resonant frequency of the ultrasonic transducer are changed.
In one possible embodiment, the relationship between the amount of charge stored by the insulating layer and the bandwidth fraction of the ultrasound transducer is a direct proportional relationship, and the relationship between the amount of charge stored by the insulating layer and the resonant frequency of the ultrasound transducer is an inverse proportional relationship.
According to the ultrasonic transducer, the substrate can tunnel charges in the substrate into the insulating layer and store the charges in the insulating layer under the action of the preset voltage, the ultrasonic transducer obtains a large bandwidth fraction through charge tunneling, and the resonant frequency can be adjusted through an electrical control method. According to the parameter configuration method of the ultrasonic transducer, the preset voltage is applied to the substrate, the charges of the substrate tunnel to the insulating layer under the action of the preset voltage, the insulating layer stores the charges with the preset number, the ultrasonic transducer obtains a large bandwidth fraction by using the charge tunneling method, the resonant frequency of the ultrasonic transducer is regulated and controlled by an electrical method, the resonant frequency of the ultrasonic transducer is adjusted without changing the physical structure size, and the design freedom degree is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an ultrasonic transducer provided in an embodiment of the present application;
fig. 2 is a schematic diagram illustrating an application principle of an ultrasonic transducer according to an embodiment of the present application;
fig. 3 is a schematic flowchart of a method for configuring parameters of an ultrasonic transducer according to an embodiment of the present application;
fig. 4 is a schematic flowchart of another ultrasonic transducer parameter configuration method provided in an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application.
The terms "first," "second," and the like in the description and claims of the present application and in the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
For a better understanding of the embodiments of the present application, reference will now be made in detail to the embodiments of the present application, which are illustrated in the accompanying drawings.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an ultrasonic transducer according to an embodiment of the present disclosure. The ultrasonic transducer includes: the device comprises an upper electrode 10, a vibrating diaphragm 11, an insulating layer 12 and a substrate 13, wherein the substrate is doped with a preset substance to form a lower electrode with a conductive characteristic, and the insulating layer 12 is made of a preset material with a charge storage capacity;
the upper electrode 10 is disposed on an outer surface of the diaphragm 11, the insulating layer 12 is disposed opposite to an inner surface of the diaphragm 11, a cavity 14 is formed between the diaphragm 11 and the insulating layer 12, and the insulating layer 12 is disposed on a first surface of the substrate 13, where the first surface is a surface of the substrate close to the diaphragm 11;
the substrate 13 is configured to tunnel charges of the substrate 13 to the insulating layer 12 under the action of a preset voltage, so that the insulating layer 12 stores a preset amount of charges; the preset number of charges is used for configuring the bandwidth fraction of the ultrasonic transducer to be increased to a preset bandwidth fraction and configuring the resonance frequency of the ultrasonic transducer to be a preset resonance frequency.
Here, the ultrasonic transducer obtains a large bandwidth fraction by a charge tunneling method, the bandwidth fraction and the center frequency are controlled by charges by an electrical control method, the resonance frequency is not adjusted by a method of changing the physical structure size, the frequency is reduced without changing the physical size in low-frequency applications, and the problem of too large rigidity and low sensitivity due to too small size for improving the resonance frequency in high-frequency applications is not required, so that the design freedom of the ultrasonic transducer is improved.
The structure of the insulating layer includes: a first sub-insulating layer 121 and a second sub-insulating layer 122 are stacked.
The first sub-insulating layer 121 is a charge trapping layer, the second sub-insulating layer 122 is a charge tunneling layer, and the second self-insulating layer 122 is disposed between the first sub-insulating layer 121 and the substrate 13.
Here, the charge-trapping layer is used to store tunneling charges, the substrate generates tunneling charges under a predetermined voltage, and the tunneling charges tunnel in the insulating layer and are stored in the charge-trapping layer.
In other embodiments, the insulating layer 12 may be a single insulating layer.
Wherein the thickness of the insulating layer 12 is 16-55 nm. It should be noted that, in other embodiments, the thickness of the insulating layer 12 may take other values.
The preset material can be any one of silicon oxynitride and polysilicon. It should be noted that in other embodiments, other materials with charge storage capability may be used.
Wherein the preset substance comprises: aluminum. It should be noted that in other embodiments, other substances with conductive capability may be used.
The relation between the preset number of charges and the bandwidth fraction of the ultrasonic transducer is a direct proportion relation, and the relation between the number of charges stored in the insulating layer and the resonance frequency of the ultrasonic transducer is an inverse proportion relation.
According to the ultrasonic transducer provided by the embodiment of the application, the preset voltage is applied to the substrate, so that charges in the substrate tunnel to the insulating layer, are captured by the insulating layer and are stored in the insulating layer, the bandwidth fraction of the ultrasonic transducer is increased, the rigidity is reduced, the resonance frequency is not reduced by changing the physical size of the ultrasonic transducer, the bandwidth fraction and the resonance frequency of the ultrasonic transducer are regulated and controlled through an electrical method, and the design freedom degree of the ultrasonic transducer is improved.
The ultrasonic transducer according to the embodiment of the present application is described above, and the method for configuring the parameters of the ultrasonic transducer according to the embodiment of the present application is described below.
Referring to fig. 3, fig. 3 is a schematic flowchart of a method for configuring parameters of an ultrasonic transducer according to an embodiment of the present application, where the method includes:
s101, providing an ultrasonic transducer, wherein the ultrasonic transducer includes: the substrate is doped with a preset substance to form a lower electrode with a conductive characteristic, and the insulating layer is made of a preset material with charge storage capacity;
the upper electrode is arranged on the outer surface of the vibrating diaphragm, the insulating layer is arranged relative to the inner surface of the vibrating diaphragm, a cavity is formed between the vibrating diaphragm and the insulating layer, the insulating layer is arranged on the first surface of the substrate, and the first surface is the surface, close to the vibrating diaphragm, of the substrate;
s102, applying a preset voltage to the substrate, and tunneling charges of the substrate to the insulating layer under the action of the preset voltage, so that a preset number of charges are stored in the insulating layer, and the preset number of charges are used for configuring the bandwidth fraction of the ultrasonic transducer to be increased to a preset bandwidth fraction and configuring the resonance frequency of the ultrasonic transducer to be a preset frequency.
Wherein the relation between the quantity of the charges stored by the insulating layer and the bandwidth fraction of the ultrasonic transducer is a direct proportion relation, and the relation between the quantity of the charges stored by the insulating layer and the resonance frequency of the ultrasonic transducer is an inverse proportion relation.
In the parameter configuration method for the ultrasonic transducer provided in the embodiment of the present application, a preset voltage is applied to a substrate of the ultrasonic transducer to generate a tunneling charge, and the tunneling charge is tunneled in an insulating layer and stored in the insulating layer, that is, an electret is formed by a tunneling charge method, where a tunneling method adopted by the tunneling charge is Fowler-Nordheim charge tunneling, that is, an electrically-assisted charge tunneling method. The tunneling charges generate electrostatic fields, and the electrostatic forces formed by the tunneling charges cause rigidity reduction, resonance frequency reduction, damping coefficient increase, quality factor reduction and bandwidth fraction increase. The large bandwidth fraction is obtained by using a charge tunneling mode, the resonance frequency of the ultrasonic transducer is regulated and controlled by an electrical method, the bandwidth fraction and the center frequency are controlled by charges, the ultrasonic transducer does not need to be increased in size to reduce the resonance frequency in low-frequency application, the ultrasonic transducer does not need to be reduced in size to obtain the high center frequency in high-frequency application, namely, the resonance frequency is not adjusted by adjusting the physical structure size of the ultrasonic transducer, and the design freedom degree of the ultrasonic transducer is improved.
Referring to fig. 4 again, fig. 4 is a schematic flowchart of another ultrasound transducer parameter configuration method provided in an embodiment of the present application, where the method includes:
s201, providing an ultrasonic transducer, wherein the ultrasonic transducer includes: the substrate is doped with a preset substance to form a lower electrode with a conductive characteristic, and the insulating layer is made of a preset material with charge storage capacity;
the upper electrode is arranged on the outer surface of the vibrating diaphragm, the insulating layer is arranged relative to the inner surface of the vibrating diaphragm, a cavity is formed between the vibrating diaphragm and the insulating layer, the insulating layer is arranged on the first surface of the substrate, and the first surface is the surface, close to the vibrating diaphragm, of the substrate.
S202, applying a preset voltage to the substrate, and tunneling charges of the substrate to the insulating layer under the action of the preset voltage, so that a preset number of charges are stored in the insulating layer, where the preset number of charges is used to configure the bandwidth fraction of the ultrasonic transducer to increase to a preset bandwidth fraction, and configure the resonant frequency of the ultrasonic transducer to be a preset frequency.
S203, adjusting the preset voltage to adjust the quantity of the charges stored in the insulating layer, so that the bandwidth fraction and the resonant frequency of the ultrasonic transducer are changed.
The number of the charges stored in the insulating layer is changed by adjusting the preset voltage, so that the bandwidth fraction and the resonance frequency of the ultrasonic transducer are influenced, the resonance frequency of the ultrasonic transducer is regulated and controlled by an electrical method, and the resonance frequency is not adjusted by changing the physical size. The design of the ultrasonic transducer is independent of the physical structure size and is realized by an electric regulation method, the frequency is not reduced by the physical size in low-frequency application, the problem of overlarge rigidity and low sensitivity caused by increasing the central frequency by undersize is not needed in high-frequency application, and the design freedom degree is improved.
Wherein the relation between the quantity of the charges stored by the insulating layer and the bandwidth fraction of the ultrasonic transducer is a direct proportion relation, and the relation between the quantity of the charges stored by the insulating layer and the resonance frequency of the ultrasonic transducer is an inverse proportion relation.
The above is a description of an embodiment of the present application, and the following is a description of the principle of using charge tunneling to improve the bandwidth fraction and the operation process of the ultrasound transducer provided by the present application.
Referring to fig. 2, fig. 2 is a schematic diagram illustrating an application principle of an ultrasonic transducer according to an embodiment of the present application. The doped substrate 13 forms a lower electrode, and the upper electrode 10, the cavity 14 and the lower electrode form a capacitor Cub. The tunneling charges in the insulating layer 12 generate an electrostatic field, and the diaphragm 11 is at the equilibrium position x under the action of the electrostatic force of the electrostatic field0The equivalent DC bias voltage is represented by V0, when transmitting, the upper electrode 10 is only excited by the AC voltage Vi, without the DC bias voltage, the diaphragm 11 vibrates to push the airA medium, generating sound waves.
When charges tunnel into the insulating layer 12, the diaphragm electrostatic force is generated by the excitation voltage and the charges, forming the cavity of the ultrasonic transducer when the sacrificial layer process is performed, and the charges are buried in the insulating layer 12 instead of the dc bias voltage. After pulse excitation, sound waves are emitted.
The sound pressure vibration causes the capacitance between the upper and lower electrodes to change when receiving.
From (1), the force of the vibration change is generated by the electric charge. Term 2 is constant at equilibrium position.
The diaphragm 11 is subjected to electrostatic force, resistance force, diaphragm restoring force, and force analysis,
b is a resistance coefficient, k is a diaphragm equivalent spring coefficient, x0Is the equilibrium position.
The finishing process comprises the following steps:
kQthe electrostatic force generated by the tunneling charge in the insulating layer is equivalent to the spring constant. k' is the equivalent spring coefficient of the diaphragm using tunneling charge method in the insulating layer.
The damping coefficient ζ and the bandwidth fraction FBW are as follows:
m is the diaphragm mass, BwIs the bandwidth, fcIs the center frequency.
From (4), the rigidity is reduced by using a tunneling charge method, the resonance frequency is reduced, and the size is not increased to reduce the realization of low-frequency application; the damping coefficient is increased, the quality factor is reduced, and the bandwidth fraction is increased.
It should be noted that, for simplicity of description, the foregoing embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present application is not limited by the order of acts, as some steps may occur in other orders or concurrently depending on the application. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred and that no particular act is required to implement the invention.
In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application with specific examples, and the above description of the embodiments is only provided to help understand the present application and its core ideas; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific implementation and application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (1)
1. A method for configuring parameters of an ultrasonic transducer, the method comprising:
providing an ultrasound transducer, said ultrasound transducer comprising: the substrate is doped with a preset substance to form a lower electrode with a conductive characteristic, and the insulating layer is made of a preset material with charge storage capacity;
the upper electrode is arranged on the outer surface of the vibrating diaphragm, the insulating layer is arranged relative to the inner surface of the vibrating diaphragm, a cavity is formed between the vibrating diaphragm and the insulating layer, the insulating layer is arranged on the first surface of the substrate, and the first surface is the surface, close to the vibrating diaphragm, of the substrate;
applying a preset voltage on the substrate, wherein charges of the substrate tunnel to the insulating layer under the action of the preset voltage, so that a preset number of charges are stored in the insulating layer, and the preset number of charges are used for configuring the bandwidth fraction of the ultrasonic transducer to be increased to a preset bandwidth fraction and configuring the resonance frequency of the ultrasonic transducer to be a preset frequency;
wherein the relation between the quantity of the charges stored by the insulating layer and the bandwidth fraction of the ultrasonic transducer is a direct proportion relation, and the relation between the quantity of the charges stored by the insulating layer and the resonance frequency of the ultrasonic transducer is an inverse proportion relation; the method further comprises the following steps: adjusting the preset voltage to adjust the quantity of the charges stored in the insulating layer, so that the bandwidth fraction and the resonant frequency of the ultrasonic transducer are changed; wherein the electric charge generates an electrostatic field, and the bandwidth fraction and the resonance frequency are adjusted by an electrostatic force formed by the electric charge.
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| JP3611779B2 (en) * | 1999-12-09 | 2005-01-19 | シャープ株式会社 | Electrical signal-acoustic signal converter, method for manufacturing the same, and electrical signal-acoustic converter |
| CN101612614B (en) * | 2009-07-03 | 2011-03-09 | 深圳清研技术管理有限公司 | Ultrasonic wave detector |
| JP2016101417A (en) * | 2014-11-28 | 2016-06-02 | キヤノン株式会社 | Capacitance-type acoustic wave transducer and subject information acquisition apparatus with the same |
| CN108722837A (en) * | 2018-05-22 | 2018-11-02 | 清华大学 | A kind of capacitive ultrasound transducer and its manufacturing method |
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