WO2020102965A1

WO2020102965A1 - Ultrasonic transducer and electronic device

Info

Publication number: WO2020102965A1
Application number: PCT/CN2018/116369
Authority: WO
Inventors: 王红超; 沈健; 李运宁
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2020-05-28
Also published as: CN109643378B; CN109643378A

Abstract

An ultrasonic transducer and an electronic device, wherein the ultrasonic transducer comprises: a sensing dielectric layer (40), an ultrasonic reception layer (20) capable of receiving ultrasonic waves and an ultrasonic emission layer (10) capable of emitting ultrasonic waves, wherein, the ultrasonic emission layer (10) and the ultrasonic reception layer (20) are stacked below the sensing dielectric layer (40), so that the ultrasonic transducer has a stronger ultrasonic emission capability and a better reception effect, thereby solving the problem that poor ultrasonic generation capability affects the performance in existing ultrasonic transducers.

Description

Ultrasonic transducer and electronic device

Technical field

The present application relates to the field of ultrasonic imaging technology, and in particular to an ultrasonic transducer and electronic device.

Background technique

With the development of biometrics technology, more and more terminals are equipped with biometrics chips. The micromachined ultrasonic transducer (CMUT) is a relatively common biometric sensor, which actively emits high-frequency sound waves through the screen to reach the surface of the organism, and then collects the ultrasonic echo in the pressing area to form Skin feature image, and finally compare the skin feature image with the stored image to complete the functions of fingerprint recognition and living body detection.

At present, the CMUT usually includes a substrate, a lower electrode, an etched sacrificial layer, a support layer, a diaphragm layer, and an upper electrode that are arranged in sequence, and then achieves independent control of the array elements of the ultrasonic transducer device by array control of the lower electrode. Specifically, when a DC voltage is applied between the upper electrode and the lower electrode, the strong electrostatic field pulls the diaphragm layer toward the substrate, and then an AC voltage is applied between the upper electrode and the lower electrode. When vibration occurs, ultrasonic waves are generated and emitted outward; on the contrary, the diaphragm layer vibrates under the action of ultrasonic waves, and the capacitance between the two electrode plates changes. By detecting this change, the ultrasonic waves are received, that is, the transmission and reception of ultrasonic waves are caused by The lower electrode, the diaphragm layer and the upper electrode are completed together.

However, in the above-mentioned ultrasonic transducer, the ultrasonic wave is emitted by vibrating the diaphragm layer to generate ultrasonic waves. However, when the diaphragm layer vibrates and emits ultrasonic waves, the transmitting ability is often poor, which greatly reduces the performance of the ultrasonic transducer device.

Summary of the invention

The present application provides an ultrasonic transducing device and an electronic device, which realizes the purpose that the ultrasonic transducing device has a strong ultrasonic emission capability, and solves the problem that the performance of the ultrasonic transducing device is reduced due to the poor ultrasonic emission capability of the existing CMUT problem

In a first aspect, the present application provides an ultrasonic transducer device, including: a sensing medium layer, an ultrasonic receiving layer capable of receiving ultrasonic waves, and an ultrasonic emitting layer capable of transmitting ultrasonic waves, wherein the ultrasonic emitting layer and the ultrasonic receiving layer The stack is disposed under the sensing medium layer.

In a specific embodiment of the present application, specifically, the ultrasonic emission layer includes a first electrode layer, a piezoelectric layer, and a second electrode layer, wherein the first electrode layer and the second electrode layer respectively cover the The upper and lower surfaces of the piezoelectric layer, the piezoelectric layer is used to emit ultrasonic waves on the entire surface when an alternating voltage is applied between the first electrode layer and the second electrode layer.

In specific embodiments of the present application, specifically, the piezoelectric layer is a film layer made of any of the following materials:

Piezoelectric ceramics, piezoelectric single crystals or piezoelectric polymer materials;

The first electrode layer and the second electrode layer are film layers made of any one of aluminum, copper, silver, and nickel.

In specific embodiments of the present application, specifically, the projection areas of the first electrode layer and the second electrode layer on the piezoelectric layer respectively completely overlap the front and back sides of the piezoelectric layer.

In a specific embodiment of the present application, specifically, it further includes: a backing, and the ultrasonic wave emitting layer and the ultrasonic wave receiving layer are stacked between the backing and the sensing medium layer.

In a specific embodiment of the present application, specifically, the ultrasonic emitting layer is located between the ultrasonic receiving layer and the backing, or,

The ultrasonic emission layer is located between the sensing medium layer and the ultrasonic reception layer.

In a specific embodiment of the present application, specifically, the ultrasonic receiving layer is composed of a transducer having at least one vibrating element, and the transducer is any one of the following transducers:

Capacitive micromachined ultrasonic transducer (CMUT), piezoelectric micromachined ultrasonic transducer (PMUT) or piezoelectric polymer ultrasonic transducer.

In a specific embodiment of the present application, specifically, the vibrator includes a plurality of third electrode layers provided on the substrate and isolated from each other, a diaphragm layer, and a fourth electrode layer provided on the diaphragm layer , Wherein a cavity is formed between each third electrode and the diaphragm layer, and adjacent cavities are isolated from each other.

In a specific embodiment of the present application, specifically, the ultrasonic wave receiving layer further includes: a substrate, wherein the substrate is provided with a plurality of grooves for mounting the third electrode layer;

A plurality of spacers are provided on the substrate, and the spacers divide the gap between the substrate and the diaphragm layer into a plurality of cavities corresponding one-to-one with the third electrode layer .

In a specific embodiment of the present application, specifically, the spacer is integrally formed with the substrate, or the spacer is provided on the substrate by bonding.

In a specific embodiment of the present application, specifically, a control circuit is further provided on the substrate, wherein the control circuit is electrically connected to the third electrode layer.

In specific embodiments of the present application, specifically, the projection area of the fourth electrode layer on the diaphragm layer completely covers the diaphragm layer, or the fourth electrode layer is a plurality of separated from each other An electrode layer corresponding to the third electrode layer.

In specific embodiments of the present application, specifically, the material of the diaphragm layer is polysilicon or silicon nitride;

The third electrode layer and the fourth electrode layer are made of any one of aluminum, copper, silver, and nickel.

In a specific embodiment of the present application, specifically, it further includes: a transition layer, wherein the transition layer is located between the sensing medium layer and the ultrasonic wave receiving layer, or between the sensing medium layer and the Between ultrasonic emission layers.

In a specific embodiment of the present application, specifically, the sensing medium layer is a screen, glass, or metal layer.

In a specific embodiment of the present application, specifically, it further includes: an adhesive layer covering the connection of each film layer on the outer surface of the ultrasonic transducer.

In a second aspect, the present application provides an electronic device, comprising: any one of the ultrasonic transducer devices described above, and the electronic device has an ultrasonic scanning area corresponding to the ultrasonic transducer device.

In specific embodiments of the present application, specifically, the ultrasound scan area is located in the display area of the display screen of the electronic device or in the non-display area of the electronic device.

In a specific embodiment of the present application, specifically, the shape of the ultrasound scanning area is a circle, a square, an ellipse, or an irregular figure.

The ultrasonic transducing device and the electronic device provided by this application, through the separation of the ultrasonic transmitting layer and the ultrasonic receiving layer, so that the ultrasonic transmitting layer and the ultrasonic receiving layer do not need to take into account the dual purpose of transmitting and receiving at the same time when choosing materials, the stronger transmitting ability is selected Piezoelectric materials and materials with better receiving effect, that is, the ultrasonic emission layer can use piezoelectric materials with larger amplitude under the action of voltage, so that the ultrasonic emission layer has a stronger ultrasonic emission capability and a larger action distance, making the ultrasonic transducing device Compared with the prior art, it avoids the problem of poor ultrasonic transmission ability caused by the selection of materials with smaller amplitude. Correspondingly, due to the better reception effect in the existing ultrasonic transducer, this implementation In the example, the ultrasonic receiving layer may use the same material as the diaphragm layer in the prior art. Therefore, the ultrasonic transducing device provided in this embodiment realizes that the ultrasonic transducing device has a strong ultrasonic transmitting capability and better reception The purpose of the effect is to make the working performance of the ultrasonic transducer better, thereby solving the problem that the existing ultrasonic transducer has poor ultrasonic emission capability and affects the performance of the ultrasonic transducer.

BRIEF DESCRIPTION

In order to more clearly explain the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required in the embodiments or the description of the prior art. Obviously, the drawings in the following description These are some embodiments of the present application. For those of ordinary skill in the art, without paying creative labor, other drawings may be obtained based on these drawings.

FIG. 1 is a schematic cross-sectional structural diagram of an ultrasound transducer device provided in Embodiment 1 of the present application;

2 is a schematic diagram of a cross-sectional structure of each layer in the ultrasonic transducer device provided in Embodiment 1 of the present application;

3 is a schematic diagram of the arrangement of the vibrating elements in the ultrasonic receiving layer in the ultrasonic transducing device provided in Embodiment 1 of the present application;

4 is a schematic structural diagram of a cross-sectional structure of each layer in an ultrasonic transducer device provided in Embodiment 2 of the present application;

5 is a schematic structural diagram of an electronic device provided in Embodiment 3 of the present application.

Through the above drawings, a clear embodiment of the present disclosure has been shown, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the concept of the present disclosure in any way, but to explain the concept of the present disclosure to those skilled in the art by referring to specific embodiments.

Description of reference signs:

10-Ultrasonic emission layer; 11-first electrode layer; 12-second electrode layer;

13- Piezoelectric layer; 101-pulse sound wave; 102-focused beam;

103-reflected beam; 104-biological structure; 105-valley;

106-ridge; 20-ultrasonic receiving layer; 21-vibrator; 20-ultrasonic receiving layer;

22-spacer; 23-substrate; 211-diaphragm layer;

212-partition; 213- third electrode layer; 214- fourth electrode layer;

215-cavity; 30-transition layer; 40-sensing medium layer;

50-backing; 100-electronic device; 110-display screen;

120-Ultrasonic scanning area.

detailed description

To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

The technical solution of the present application will be described in detail below with specific embodiments. The following specific embodiments may be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

In the following, some terms in this application will be explained to facilitate understanding by those skilled in the art.

Capacitive micromachined ultrasonic transducer (CMUT) is a micro-electromechanical device that utilizes the mutual conversion of acoustic energy and electrical energy. It has the advantages of high integration, good sensitivity, and wide receiving bandwidth. It is used to make ultrasonic transducers. Ideal device. The CMUT can convert ultrasonic waves into electrical signals and electrical signals into ultrasonic waves. When a DC voltage is applied between the upper electrode and the lower electrode, the strong electrostatic field pulls the diaphragm layer toward the substrate, and then an AC voltage is applied between the upper electrode and the lower electrode. At this time, the diaphragm layer will vibrate. Generate ultrasonic waves. On the contrary, after applying an appropriate DC bias voltage between the upper electrode and the lower electrode, the diaphragm layer vibrates under the action of ultrasonic waves, and the capacitance between the two electrode plates changes. By detecting this change, ultrasonic waves are received.

As described in the background art, the existing ultrasonic transducer has a problem of poor ultrasonic emission capability. The reason for this problem is that the existing ultrasonic transducer applies a DC voltage between the upper electrode and the lower electrode. The AC voltage causes the diaphragm layer to vibrate to generate ultrasonic waves and emit. At the same time, the diaphragm layer vibrates under the action of ultrasonic waves, and the capacitance between the two electrode plates changes. By detecting this change, the ultrasonic waves are received, that is, the existing In ultrasonic transducers, the diaphragm layer takes into account the dual role of transmitting and receiving ultrasonic waves at the same time, so the diaphragm layer is often made of polysilicon or silicon nitride material, and the reflected resonance frequency of ultrasonic waves is proportional to the thickness of the film layer. The accuracy of image recognition and the frequency of ultrasonic transmission are generally in the range of 10Mhz ~ 25MHz. In order to obtain the corresponding thickness of the diaphragm at this frequency, the CMUT needs to be very thick, and at the same time the diameter is small. Due to the limitation of the device voltage, the voltage that can be allocated to the CMUT device is generally low, which ultimately causes the amplitude of the diaphragm to be small and thus reduces the ability to emit ultrasonic waves. When the diaphragm layer is made of a material with a larger amplitude, the diaphragm The ability of the layer to receive sound waves is greatly reduced.

Based on the above reasons, the present application provides an ultrasonic transducing device. The following describes in detail the technical solutions of the present application and how the technical solutions of the present application solve the above technical problems in specific embodiments. The following specific embodiments may be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below with reference to the drawings.

Example one

1 is a schematic diagram of a cross-sectional structure of an ultrasonic transducer device provided by Example 1 of the present application, FIG. 2 is a schematic diagram of a cross-sectional structure of each layer in the ultrasonic transducer device provided by Example 1 of the present application, and FIG. 3 is provided by Example 1 of the present application Schematic diagram of the arrangement of the vibrating elements in the ultrasonic receiving layer in the ultrasonic transducer device.

The ultrasonic transducing device provided in this embodiment can be applied in the field of fingerprint identification, and is used to implement functions such as authorized booting, admission, and credit payment for the current user.

Referring to FIGS. 1-3, the ultrasonic transducing device includes: a sensing medium layer 40, an ultrasonic receiving layer 20 capable of receiving ultrasonic waves, and an ultrasonic emitting layer 10 capable of transmitting ultrasonic waves, wherein the ultrasonic emitting layer 10 and the ultrasonic receiving layer 20 are laminated It is disposed under the sensing medium layer 40, that is, the sensing medium layer 40 is located at the top layer of the ultrasonic transducer device, and the sensing medium layer 40 is the outer surface of the ultrasonic transducer device for sensing characteristic biological information such as fingerprints, etc. The sensing medium layer 40 may be specifically composed of a material such as a screen, glass, or metal plating. In this embodiment, the ultrasound emitting layer 10 and the ultrasound receiving layer 20 are located below the sensing medium layer 40, and the ultrasound emitting layer 10 and the ultrasound receiving layer 20 When stacked, specifically, the ultrasonic receiving layer 20 may be located between the ultrasonic emitting layer 10 and the sensing medium layer 40 (refer to FIG. 1), or the ultrasonic emitting layer 10 is located between the ultrasonic receiving layer 20 and the sensing medium layer 40 Among them, in this embodiment, the ultrasonic wave transmitting layer 10 is used to generate ultrasonic waves and emitted outward, and the ultrasonic wave receiving layer 20 is used to receive the returned ultrasonic waves. Specifically, the ultrasonic wave receiving layer 20 is used to receive the ultrasonic waves emitted by the ultrasonic wave transmitting layer 10 The echo returned by the skin reflection, so that the control unit images the skin characteristics according to the echo signal received by the ultrasound receiving layer 20, and compares it with the image information stored in the terminal to realize the biometric function.

Among them, in the ultrasonic transducing device provided in this embodiment, since the film layer transmitting the ultrasonic wave and the film layer receiving the ultrasonic wave are two independent film layers, the ultrasonic wave transmitting layer 10 may be responsible for transmitting ultrasonic waves, and the ultrasonic wave receiving layer 20 may be responsible for receiving The returned ultrasonic wave, so that the ultrasonic transmitting layer 10 and the ultrasonic receiving layer 20 do not need to take into account the dual purpose of transmitting and receiving at the same time, and can choose materials with stronger transmitting ability and materials with better receiving effect, for example, the ultrasonic transmitting layer 10 A material with a large amplitude under the action of a voltage, such as a piezoelectric material, can be selected, so that the ultrasonic emission layer 10 has a strong ultrasonic emission capability and a large action distance, so that the performance of the ultrasonic transduction device is better, compared with the prior art , To avoid the problem of poor ultrasonic transmission capability caused by the use of a diaphragm with a small amplitude. Correspondingly, because the receiving effect of the existing ultrasonic transducer is better, in this embodiment, the ultrasonic receiving layer 20 can be selected as The materials of the diaphragm layer in the prior art are the same. Therefore, the ultrasonic transducer device provided in this embodiment achieves the purpose of the ultrasonic transducer device having a strong ultrasonic transmission capability and a good receiving effect, so that the ultrasonic transducer device Has better working performance, thereby solving the problem that the existing ultrasonic transducer has poor ultrasonic emission capability and affects the performance of the ultrasonic transducer.

Further, on the basis of the foregoing embodiment, in this embodiment, referring to FIG. 2, the ultrasonic emission layer 10 includes a first electrode layer 11, a piezoelectric layer 13 and a second electrode layer 12, wherein the first electrode layer 11 and the second electrode layer 12 respectively cover the front and back surfaces of the piezoelectric layer 13, the piezoelectric layer 13 is used to emit ultrasonic waves on the entire surface when an alternating voltage is applied between the first electrode layer 11 and the second electrode layer 12, ie In this embodiment, the ultrasonic emission layer 10 is specifically composed of the first electrode layer 11, the piezoelectric layer 13 and the second electrode layer 12. When an alternating voltage is applied between the first electrode layer 11 and the second electrode layer 12, the piezoelectric The entire surface of the layer 13 emits ultrasonic waves. Since the piezoelectric layer 13 uses a piezoelectric material, the vibration amplitude of the piezoelectric layer 13 is large under the action of an alternating voltage, so the ability to transmit ultrasonic waves is strong, which is similar to the diaphragm layer in the prior art. In contrast, in this embodiment, the piezoelectric layer 13 in the ultrasonic emission layer 10 can generate a constant pulsed acoustic wave under the action of a voltage, and the emission capability is relatively strong. In this embodiment, the frequency of the pulsed acoustic wave generated by the ultrasonic emission layer 10 It is determined by the applied electric field, and the characteristic wavelength range for biometrics is 15-25MHz. The piezoelectric layer 13 uses the entire surface of the piezoelectric material, so the emission is an ultrasonic surface wave with a narrow bandwidth. In this embodiment, the pressure The thickness of the electrical material determines its resonance frequency. In this embodiment, the thickness of the piezoelectric layer 13 may be 100 μm.

In this embodiment, the piezoelectric layer 13 is a film layer made of piezoelectric ceramic, piezoelectric single crystal, or piezoelectric polymer material, that is, the piezoelectric layer 13 may use piezoelectric ceramic, or the piezoelectric layer 13 may also It may be made of piezoelectric single crystal material, or the piezoelectric layer 13 may also be made of piezoelectric polymer material, wherein. Piezoelectric ceramics have strong emission capabilities, but due to the poor acoustic impedance matching between piezoelectric ceramics and air, the broadband of acoustic waves received by piezoelectric ceramics is narrow, which affects the reception capability of piezoelectric ceramics. At the same time, the purpose of transmitting and receiving is considered, and the diaphragm is often not selected from piezoelectric ceramics or other piezoelectric materials. However, in this application, because the transmission and reception of ultrasonic waves are independent of the two layers, the ultrasonic transmitting layer 10 The piezoelectric layer 13 may be piezoelectric ceramics, which greatly enhances the ultrasonic emission capability of the ultrasonic emission layer 10.

In this embodiment, the first electrode layer 11 and the second electrode layer 12 are metal conductive layers made of any material of aluminum, copper, silver, and nickel.

In this embodiment, in order to ensure that the entire surface of the piezoelectric layer 13 emits ultrasonic surface waves, specifically, the projection areas of the first electrode layer 11 and the second electrode layer 12 on the piezoelectric layer 13 are respectively different from the piezoelectric layer 13 The two sides of the front and back completely overlap, that is, the first electrode layer 11 and the second electrode layer 12 are the same full-surface electrode as the front and back sides of the piezoelectric layer 13, so that when the first electrode layer 11 and the second electrode layer 12 When an alternating electric field is applied, a constant pulse sound wave can be generated on the entire surface of the piezoelectric layer 13.

Wherein, in this embodiment, referring to FIG. 2 further includes: a backing 50, which is the bottom layer of the ultrasonic transducer, and the ultrasonic transmitting layer 10 and the ultrasonic receiving layer 20 are stacked on the backing 50 and the sensing medium Between the layers 40, in this embodiment, the backing 50 is used to absorb the ultrasonic waves propagating downward. The backing 50 may specifically use a damping material, and at the same time, the backing 50 also plays a role of heat conduction, so the backing 50 may also be used. Stainless steel metal back plate.

In this embodiment, referring to FIG. 2, the ultrasonic emission layer 10 is located between the ultrasonic receiving layer 20 and the backing 50, or the ultrasonic emission layer 10 is located between the sensing medium layer 40 and the ultrasonic receiving layer 20 (refer to As shown in FIG. 4), when the ultrasonic emitting layer 10 is located between the sensing medium layer 40 and the ultrasonic receiving layer 20, the backing 50 is located on the bottom layer of the ultrasonic receiving layer 20 at this time.

In this embodiment, referring to FIG. 1, the ultrasonic receiving layer 20 is composed of a transducer having at least one vibrating element 21, and the transducer is a capacitive micromachined ultrasonic transducer (CMUT), piezoelectric micromachined An ultrasonic transducer (PMUT) or a piezoelectric polymer ultrasonic transducer, wherein, in this embodiment, referring to FIG. 3, the number of the vibrating elements 21 is multiple, and the multiple vibrating elements 21 are arranged according to a predetermined pattern The two-dimensional array is formed into an ultrasonic receiving layer 20, in which multiple vibrating elements 21 are independent of each other, so that the received beam can be focused, wherein the isolation between the vibrating elements 21 is through the array of the lower electrode or the upper electrode To achieve this, the separation between the vibrating elements 21 may be a physical division such as the spacer 22, and the material of the spacer may be a material with a large acoustic impedance to reduce mutual interference between the vibrating elements 21.

In this embodiment, the vibrating element 21 includes a plurality of third electrode layers 213, a diaphragm layer 211, and a fourth electrode layer 214 disposed on the diaphragm layer 211, which are provided on the substrate 23 and separated from each other. A cavity 215 is formed between each third electrode and the diaphragm layer 211, and adjacent cavities 215 are isolated from each other. As shown in FIG. 2, the third electrode layers 213 are separated from each other, and each third electrode layer 213 Corresponding to a cavity 215, and the cavity 215 is specifically a vacuum cavity, which can reduce the acoustic impedance at the cavity 215, wherein the cavity 215 is isolated from each other, wherein the fourth electrode layer 214 is in the diaphragm layer 211 The projection area on the top completely covers the diaphragm layer 211, that is, the fourth electrode layer 214 is a whole electrode, or the fourth electrode layer 214 may also be a plurality of electrodes separated from each other, used to independently control the diaphragm of each vibrator 21 In the present embodiment, when the vibrating element 21 is composed of the third electrode layer 213, the diaphragm layer 211, the fourth electrode layer 214, and the cavity 215, when the third electrode layer 213 and the fourth electrode layer 214 When an alternating voltage is added between them, under the action of electrostatic force, the diaphragm layer 211 will vibrate and emit a sine wave. When the reflected sound wave / echo reaches the surface of the vibrator element 21, the diaphragm layer 211 will cause the diaphragm layer. 211 Regular vibration, the vibration will be converted into the change of voltage / potential between the upper and lower electrodes. According to the change of voltage / potential, the imaging of skin characteristics is obtained, and the image information stored in the terminal is compared to realize the function of biometric recognition.

In this embodiment, the width of the cavity 215 may be smaller than the width of the third electrode layer 213, or the width of the cavity 215 may be equal to the width of the third electrode layer 213, or the width of the cavity 215 may also be greater than the third electrode The width of layer 213.

Among them, when the ultrasonic transducer device provided in this embodiment works, the specific process is as follows: First, an alternating electric field is applied between the first electrode layer 11 and the second electrode layer 12 to generate a constant pulsed sound wave 101. When the ultrasonic beam reaches the stack In the cavity 215 structure in the layer, strong reflection occurs due to the mismatch of acoustic impedance. In contrast, the acoustic wave can normally pass through the side wall of the cavity 215 to form the focused beam 102. After the ultrasonic beam reaches the interface of the sensing medium layer 40 A characteristic reflection is formed at the interface, and a biological structure 104 with a characteristic structure, such as a finger skin, here takes a fingerprint as an example. Since the surface of the fingerprint is uneven, the convex part is regarded as the ridge 106, and the concave part is regarded as the valley 105. When the sound wave reaches the position of the valley 105 of the fingerprint, the reflected beam 103 is generated due to the large air acoustic impedance, and when the sound wave reaches the position of the fingerprint ridge 106, the transmission of the sound wave occurs due to the low acoustic impedance of the skin. Among them, the reflected beam When 103 reaches the diaphragm layer 211, the diaphragm layer 211 vibrates regularly, and the vibration of the diaphragm layer 211 causes the voltage / potential between the third electrode layer 213 and the fourth electrode layer 214 to change, depending on the detected voltage / potential Changes are imaging the skin characteristics. Therefore, in this embodiment, the strength of the echo signal of the ultrasonic wave on the skin surface is used to form an echo image, so that the characteristic information of the skin surface can be completely reflected. Finally, by comparing the skin surface feature information with pre-stored skin feature information, the purpose of biometric identification is achieved.

In this embodiment, the material of the diaphragm layer 211 may be polysilicon or silicon nitride, such as Si ₃ N ₄ , and the third electrode layer 213 and the fourth electrode layer 214 are made of aluminum, copper, silver, nickel Any one of the materials is made into a film layer.

In this embodiment, the ultrasonic receiving layer 20 further includes: a substrate 23, wherein the substrate 23 may specifically be a single crystal silicon material, and the substrate 23 is provided with a plurality of grooves for mounting the third electrode layer 213 That is, in this embodiment, a plurality of third electrode layers 213 are installed in the grooves formed on the substrate 23.

At the same time, in order to isolate the cavity 215, in this embodiment, a plurality of spacers 212 are provided on the substrate 23, and the spacer 212 separates the gap between the substrate 23 and the diaphragm layer 211 into a plurality of The electrode layers 213 correspond to the cavities 215 one by one. In this embodiment, the spacer 22 between the spacer 212 on the substrate 23 and the vibrating element 21 may be the same component, that is, the vibrating element 21 may pass through The spacer 212 is used for isolation. In this embodiment, the spacer 212 and the substrate 23 may be integrally formed. For example, a groove is formed in the substrate 23 by engraving, and a part of the space in the groove is used for placing the third electrode layer 213 The other part of the space is a cavity 215, or the spacer 212 is provided on the substrate 23 by bonding, that is, the spacer 212 is a metal fence structure added by a semiconductor process, wherein the spacer 212 is provided on the substrate by bonding When the bottom 23 is on, the spacer 212 is specifically a bonding material, such as a eutectic bonding structure of Al and Ge.

In this embodiment, the substrate 23 is not limited to the structure shown in FIG. 2. The substrate 23 is also provided with other control circuits responsible for calculation or signal processing. The control circuit is electrically connected to the third electrode layer 213. Realize signal reading and processing.

In this embodiment, since the size of the vibrator element 21 determines the resonance frequency of the CMUT, the material and size of the vibrator element 21 may be but not limited to the following combination: the diameter of the vibrator element 21 may be 25um, and the fourth electrode layer The thickness of 214 may be 0.5um, the thickness of diaphragm layer 211 (Si ₃ N ₄ ) may be 0.7um, the size of cavity 215 is 0.5um, the thickness of third electrode layer 213 is 0.5um, and the thickness of substrate 23 It can be 100um.

Wherein, in this embodiment, it further includes: a transition layer 30, wherein, as shown in FIG. 2, the transition layer 30 is located between the sensing medium layer 40 and the ultrasonic receiving layer 20, or as shown in FIG. 4, the transition layer 30 is located Between the sensing medium layer 40 and the ultrasonic emission layer 10, the transition layer 30 is specifically made of an acoustic transition layer 30 material. The transition layer 30 is used to reduce the acoustic impedance of sound wave introduction. The material of the transition layer 30 may be a layer of material, or It may be a multi-layer material that plays the role of acoustic matching and adhesive layer, such as a composite laminate material of epoxy adhesive layer and SiO ₂ .

Among them, this embodiment also includes: an adhesive layer (not shown), the adhesive layer covers the junction of each film layer on the outer surface of the ultrasonic transducer device, that is, the adhesive layer covers the film layer on the side of the ultrasonic transducer device Adhesive fixing at the connection makes it difficult to peel off the boundary of each film layer in the ultrasonic transducer, thereby improving the stability of the ultrasonic transducer.

Example 2

FIG. 4 is a schematic structural diagram of a cross-sectional structure of each layer in an ultrasonic transducer device provided in Embodiment 2 of the present application.

The difference between this embodiment and the above-mentioned embodiments is that in this embodiment, the ultrasonic emission layer 10 is located between the sensing medium layer 40 and the ultrasonic reception layer 20, and the ultrasonic reception layer 20 is located between the backing 50 and the ultrasonic emission layer 10, The transition layer 30 is located between the sensing medium layer 40 and the ultrasonic emission layer 10.

Among them, the working distance of the ultrasonic transducer device provided in this embodiment is specifically as follows: First, an alternating electric field is applied between the first electrode layer 11 and the second electrode layer 12 to generate a constant pulsed sound wave 101. When the sound wave reaches the valley of the fingerprint At the 105 position, a reflected beam is generated due to the large acoustic impedance of the air, and when the sound wave reaches the position of the fingerprint ridge 106, the transmission of the acoustic wave occurs due to the low skin acoustic impedance. When the reflected beam reaches the diaphragm layer 211, The diaphragm layer 211 vibrates regularly, and the vibration of the diaphragm layer 211 will cause the voltage / potential between the third electrode layer 213 and the fourth electrode layer 214 to change. The skin characteristics are imaged according to the detected voltage / potential change. Therefore, In this embodiment, the strength of the echo signal of the ultrasonic wave on the skin surface is used to form an echo image, so that the characteristic information of the skin surface can be completely reflected. Finally, by comparing the skin surface feature information with pre-stored skin feature information, the purpose of biometric identification is achieved.

In this embodiment, it should be noted that when the ultrasonic emitting layer 10 is located above the ultrasonic receiving layer 20, the second electrode layer 12 and the fourth electrode layer 214 may share an electrode layer, and this electrode layer may be grounded , Which reduces the arrangement of the electrode layer.

Example Three

An electronic device 100 provided in this embodiment, the electronic device 100 includes the ultrasonic transducing device of any of the above embodiments, wherein the electronic device 100 may be any device requiring feature recognition needs, such as a tablet computer, a notebook, or a mobile phone Or an access control system, etc., in this embodiment, the electronic device 100 has an ultrasonic scanning area 120 corresponding to the ultrasonic transducer. When installed, the sensing medium layer 40 of the ultrasonic transducer is located in the ultrasonic scanning area 120 or directly It is exposed at the ultrasound scanning area 120. When used, the user's finger can be placed on the ultrasound scanning area 120 to be recognized by the ultrasound transducer.

Among them, the electronic device 100 provided in this embodiment, because the ultrasonic transducing device includes an independent ultrasonic transmitting layer 10 and an ultrasonic receiving layer 20, this makes the ultrasonic transducing device have a strong ultrasonic transmitting capability and good ultrasonic receiving The capability makes the performance of the ultrasonic transducing device better, which makes the recognition accuracy and precision of the electronic device 100 higher.

The electronic device 100 provided in this embodiment may specifically have a display screen 110 for display. At this time, the ultrasound scanning area 120 is located on the display area of the display screen 110 of the electronic device 100. For example, the ultrasound transducer device may Set below the display screen 110 of the electronic device 100, so that the user can directly input fingerprints in the display area of the display screen 110; or, the ultrasound scanning area 120 is located on the non-display area of the electronic device 100, such as the frame of the electronic device 100 Above, the ultrasound scanning area 120 is an independent button area.

In this embodiment, the shape of the ultrasound scanning area 120 may be, but not limited to, a circle, a square, an ellipse, or an irregular figure.

In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection or can be through the middle The media is indirectly connected, which can be the connection between two components or the interaction between the two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", The orientation or positional relationship indicated by "outside" is based on the orientation or positional relationship shown in the drawings, only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, It is constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In the description of this application, the meaning of "plurality" is two or more, unless it is specifically and precisely specified otherwise.

The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of this application and the above drawings are used to distinguish similar objects without using To describe a specific order or sequence. It should be understood that the data used in this way are interchangeable under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, processes, methods, systems, products or devices that contain a series of steps or units need not be limited to those clearly listed Those steps or units, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or equipment.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not deviate from the essence of the corresponding technical solutions of the technical solutions of the embodiments of the present application. range.

Claims

An ultrasonic transducing device, characterized by comprising: a sensing medium layer (40), an ultrasonic receiving layer (20) capable of receiving ultrasonic waves, and an ultrasonic emitting layer (10) capable of transmitting ultrasonic waves, wherein the ultrasonic emitting layer (10) The ultrasonic receiving layer (20) is stacked under the sensing medium layer (40).
The ultrasonic transducer device according to claim 1, characterized in that the ultrasonic emission layer (10) comprises a first electrode layer (11), a piezoelectric layer (13) and a second electrode layer (12), wherein, The first electrode layer (11) and the second electrode layer (12) respectively cover the upper and lower surfaces of the piezoelectric layer (13), and the piezoelectric layer (13) is used in the first When an alternating voltage is applied between the electrode layer (11) and the second electrode layer (12), the entire surface emits ultrasonic waves.
The ultrasonic transducer according to claim 2, characterized in that the piezoelectric layer (13) is a film layer made of any of the following materials:

Piezoelectric ceramics, piezoelectric single crystals or piezoelectric polymer materials;

The first electrode layer (11) and the second electrode layer (12) are film layers made of any one of aluminum, copper, silver, and nickel.
The ultrasonic transducer according to claim 2, characterized in that the projection areas of the first electrode layer (11) and the second electrode layer (12) on the piezoelectric layer (13) are respectively The front and back sides of the piezoelectric layer (13) completely overlap.
The ultrasonic transducer according to claim 2, further comprising: a backing (50), and the ultrasonic emitting layer (10) and the ultrasonic receiving layer (20) are stacked on the backing (50) and the sensing medium layer (40).
The ultrasonic transducer device according to claim 5, characterized in that the ultrasonic wave transmitting layer (10) is located between the ultrasonic wave receiving layer (20) and the backing (50), or,

The ultrasonic emission layer (10) is located between the sensing medium layer (40) and the ultrasonic reception layer (20).
The ultrasonic transducer device according to any one of claims 1-6, characterized in that the ultrasonic receiving layer (20) is composed of a transducer having at least one vibrating element (21), and the transducer is Any one of the following transducers:

Capacitive micromachined ultrasonic transducer CMUT, piezoelectric micromachined ultrasonic transducer PMUT or piezoelectric polymer ultrasonic transducer.
The ultrasonic transducer device according to claim 7, wherein the vibrator element (21) includes a plurality of third electrode layers (213), a diaphragm layer (211) and a plurality of third electrode layers (213) provided on the substrate and isolated from each other A fourth electrode layer (214) provided on the diaphragm layer (211), wherein a cavity (215) is formed between each of the third electrodes and the diaphragm layer (211) and is adjacent The cavities (215) are isolated from each other.
The ultrasonic transducer device according to claim 8, characterized in that the ultrasonic receiving layer (20) further comprises: a substrate (23), wherein a plurality of substrates (23) are provided for mounting The groove of the third electrode layer (213);

A plurality of spacers are provided on the substrate (23), and the spacers divide the gap between the substrate (23) and the diaphragm layer (211) into a plurality of third electrodes The cavities (215) correspond to layers (213) in one-to-one correspondence.
The ultrasonic transducer according to claim 9, wherein the spacer is integrally formed with the substrate (23), or the spacer is provided on the substrate (23) by bonding .
The ultrasonic transducer device according to claim 9, wherein a control circuit is further provided on the substrate (23), wherein the control circuit is electrically connected to the third electrode layer (213).
The ultrasonic transducer device according to any one of claims 8 to 11, wherein the projection area of the fourth electrode layer (214) on the diaphragm layer (211) completely covers the diaphragm layer ( 211), or the fourth electrode layer (214) is a plurality of electrode layers separated from each other and corresponding to the third electrode layer (213).
The ultrasonic transducer device according to any one of claims 8 to 11, wherein the material of the diaphragm layer (211) is polysilicon or silicon nitride;

The third electrode layer (213) and the fourth electrode layer (214) are made of any one of aluminum, copper, silver and nickel.
The ultrasonic transducer device according to any one of claims 1-6, further comprising: a transition layer (30), wherein the transition layer (30) is located on the sensing medium layer (40) and the Between the ultrasonic receiving layer (20) or between the sensing medium layer (40) and the ultrasonic emitting layer (10).
The ultrasonic transducer device according to any one of claims 1 to 6, wherein the sensing medium layer (40) is a screen, glass, or metal layer.
The ultrasonic transducer device according to any one of claims 1-6, further comprising: an adhesive layer covering the junction of each film layer on the outer surface of the ultrasonic transducer device.
An electronic device, characterized by comprising: the ultrasonic transducer device according to any one of claims 1-16 above, and the electronic device has an ultrasonic scanning area (120) corresponding to the ultrasonic transducer device.
The electronic device according to claim 17, wherein the ultrasonic scanning area (120) is located in a display area of a display screen (110) of the electronic device or in a non-display area of the electronic device.
The electronic device according to claim 17, wherein the shape of the ultrasonic scanning area (120) is a circle, a square, an ellipse, or an irregular pattern.