Ultrasonic fingerprint sensor, ultrasonic fingerprint detection device and electronic equipment

Abstract

The embodiment of the utility model relates to the field of ultrasonic fingerprint sensors, and discloses an ultrasonic fingerprint sensor, an ultrasonic fingerprint detection device and electronic equipment. The ultrasonic fingerprint sensor comprises a substrate, a bonding pad area, an acoustic-electric conversion structure, a pressure sensitive structure and a protective layer, the acoustic-electric conversion structure and the bonding pad area are arranged on the upper surface of the substrate, and the acoustic-electric conversion structure is electrically connected with the bonding pad area; the pressure sensitive structure is arranged on the upper surface of the substrate, and the pressure sensitive structure and the acoustic-electric conversion structure are arranged at an interval; the protective layer at least covers the pressure sensitive structure; when the ultrasonic fingerprint sensor is subjected to external pressing force, the substrate deforms to drive the pressure sensitive structure to deform. A pressure sensitive structure is integrated in the ultrasonic fingerprint sensor, and a pressure detection function is utilized to identify a mistaken touch behavior with low power consumption, so that power consumption is reduced. Meanwhile, the pressure detection function assists the fingerprint recognition function in fingerprint recognition, and the fingerprint recognition effect is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of ultrasonic sensor, especially ultrasonic fingerprint sensor, ultrasonic fingerprint detection device and electronic equipment. BACKGROUND

[0002] Ultrasonic sensor works by using the piezoelectric and inverse piezoelectric characteristics of piezoelectric materials. On the one hand, by the inverse piezoelectric effect, the high voltage output by the drive circuit excites the sensor to emit ultrasonic signals, and on the other hand, by the piezoelectric effect, the ultrasonic signals reflected from the outside are converted into electrical signals, thereby obtaining the information of the sensing surface. After decades of development, current ultrasonic fingerprint sensors can be widely used in medical imaging, structure detection, and biometric identification fields. For example, ultrasonic sensors are applied to ultrasonic fingerprint modules, which are arranged in a specific area of the screen of electronic devices including but not limited to smart phones, and can be used for fingerprint identification to realize user identity authentication and enhance the anti-interference and security of the product.

[0003] The inventor found that the current ultrasonic fingerprint sensor applied to fingerprint identification has at least the following disadvantages: the detection process of the piezoelectric and inverse piezoelectric effects of the ultrasonic fingerprint sensor to obtain external information has high power consumption, and in the face of frequent false touch from the outside, the ultrasonic fingerprint sensor is frequently started, causing a large consumption of device power. UTILITY MODEL CONTENT

[0004] The purpose of the embodiment of the utility model is to provide an ultrasonic fingerprint sensor, an ultrasonic fingerprint detection device, and an electronic device. By integrating a pressure sensitive structure in the ultrasonic fingerprint sensor, a pressure detection function is integrated in the fingerprint identification function. The false touch behavior is identified by the low-power pressure detection function, and the power consumption is reduced. At the same time, the pressure detection function assists the fingerprint identification function to identify the fingerprint, and the fingerprint identification effect is improved.

[0005] To solve the above technical problems, the embodiment of the utility model provides an ultrasonic fingerprint sensor, which comprises a substrate, a pad area, an acoustic-electric conversion structure, a pressure sensitive structure, and a protective layer. The acoustic-electric conversion structure and the pad area are arranged on the upper surface of the substrate, and the acoustic-electric conversion structure is electrically connected with the pad area. The pressure sensitive structure is arranged on the upper surface of the substrate, and the pressure sensitive structure is arranged in a spaced manner with the acoustic-electric conversion structure. The protective layer covers at least the pressure sensitive structure. Under the action of external pressure, the substrate deforms to drive the pressure sensitive structure to deform.

[0006] The embodiment of the utility model also provides an ultrasonic fingerprint detection device, which comprises the above ultrasonic fingerprint sensor and a screen or a cover plate connected with the ultrasonic fingerprint sensor.

[0007] The embodiment of the utility model provides a kind of electronic equipment, comprising: above-mentioned ultrasonic fingerprint sensor or above-mentioned ultrasonic fingerprint detection device.

[0008] Compared with prior art, the substrate of the ultrasonic fingerprint sensor is not only provided with an acoustic-electric conversion structure, but also provided with a pressure sensitive structure. The pressure detection function is integrated in the fingerprint recognition function. The pressure detection function is used to assist in judging the false touch before triggering the fingerprint recognition. The acoustic-electric conversion structure is triggered to collect fingerprint data after determining that the pressure meets the requirements, thereby reducing the power consumption caused by frequent opening of the acoustic-electric conversion structure. In addition, the collected fingerprint data after meeting the pressure detection requirements can improve the quality of the fingerprint image to some extent, thereby accelerating the efficiency of fingerprint authentication and improving the fingerprint recognition effect. The combination of pressure detection and fingerprint recognition is conducive to improving the fingerprint recognition effect.

[0009] In addition, the lower surface of the substrate is provided with a groove, and the projection area of the groove towards the upper surface of the substrate at least partially overlaps with the setting area of the pressure sensitive structure.

[0010] In addition, the acoustic-electric conversion structure comprises a bottom electrode, a piezoelectric layer and a top electrode. The bottom electrode is arranged on the upper surface of the substrate. The piezoelectric layer is arranged above the substrate and covers the bottom electrode. The top electrode is arranged above the piezoelectric layer and extends to the pad area along the surface of the piezoelectric layer and the substrate surface connected with the piezoelectric layer, and is electrically connected with the pad area. The bottom electrode is arranged separately from the pad area, and the bottom electrode is arranged separately from the pressure sensitive structure.

[0011] In addition, the bottom electrode comprises a first electrode unit and a second electrode unit arranged around the first electrode unit. The minimum distance between the setting position of the pressure sensitive structure and the edge of the substrate is greater than the minimum value of the distance between all the second electrode units and the same edge.

[0012] In addition, the thickness of the pressure sensitive structure is set to be in the range of 0.1 microns to 5 microns.

[0013] In addition, the wafer is arranged at the position of the pressure sensitive structure of the substrate. In the case that the wafer is made of single crystal silicon material, the pressure sensitive structure is formed by ion implantation or diffusion doping on the wafer.

[0014] In addition, the distance between the pressure sensitive structure and the acoustic-electric conversion structure is set to be in the range of 2 microns to 50 microns.

[0015] In addition, in the ultrasonic fingerprint detection device, the screen or cover plate is fixed to the side of the ultrasonic fingerprint sensor close to the substrate, or the screen or cover plate is fixed to the side of the ultrasonic fingerprint sensor away from the substrate. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0017] Figure 1 This is a schematic diagram of the structure of the ultrasonic fingerprint sensor according to an embodiment of this solution;

[0018] Figure 2 This is a schematic diagram of the cross-sectional structure of the ultrasonic fingerprint sensor in this embodiment;

[0019] Figure 3 This is a schematic diagram of the cross-sectional structure of the ultrasonic fingerprint sensor in this embodiment;

[0020] Figure 4 This is a top view of the ultrasonic fingerprint sensor in this embodiment of the solution.

[0021] Figure 5 This is an exploded view of the ultrasonic fingerprint sensor according to an embodiment of this solution;

[0022] Figure 6 This is an exploded view of the ultrasonic fingerprint sensor according to an embodiment of this solution;

[0023] Figure 7 This is an exploded view of the ultrasonic fingerprint sensor according to an embodiment of this solution;

[0024] Figure 8 This is an exploded view of the ultrasonic fingerprint sensor according to an embodiment of this solution;

[0025] Figure 9 This is an exploded view of the ultrasonic fingerprint sensor according to an embodiment of this solution;

[0026] Figure 10 This is an exploded view of the ultrasonic fingerprint sensor according to an embodiment of this solution;

[0027] Figure 11 This is a structural schematic diagram of the ultrasonic fingerprint detection device according to an embodiment of this solution;

[0028] Figure 12 This is a structural schematic diagram of the ultrasonic fingerprint detection device according to an embodiment of this solution;

[0029] Figure 13 This is a schematic diagram of the system architecture of the ultrasonic fingerprint detection device according to the embodiments of this solution;

[0030] Figure 14 This is a flowchart of the fingerprint recognition detection method according to the embodiments of this solution. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the various embodiments of this utility model will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this utility model to enable readers to better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0032] The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this utility model. The various embodiments can be combined with or referenced by each other without contradiction.

[0033] Embodiments of this utility model relate to an ultrasonic fingerprint sensor, such as... Figure 1 As shown, the ultrasonic fingerprint sensor includes: a substrate 1, a pad area 4, an acoustic-electric conversion structure 2, a pressure-sensitive structure 3, and a protective layer 5; the acoustic-electric conversion structure 2 and the pad area 4 are both disposed on the upper surface of the substrate 1, and the acoustic-electric conversion structure 2 is electrically connected to the pad area 4; the pressure-sensitive structure 3 is disposed on the upper surface of the substrate 1, and the pressure-sensitive structure 3 and the acoustic-electric conversion structure 2 are spaced apart; the protective layer 5 covers at least the pressure-sensitive structure 3; when the ultrasonic fingerprint sensor is subjected to external pressure, the substrate 1 deforms, causing the pressure-sensitive structure 3 to deform as well.

[0034] The acoustic-electric conversion structure 2 includes: a bottom electrode 21 and a piezoelectric layer 22. Figure 1 The area delineated by the dashed line shown) and the top electrode 23 ( Figure 1 The solid line delineates the area electrically connected to the pad area 4; the bottom electrode 21 is disposed on the upper surface of the substrate 1, the piezoelectric layer 22 is disposed above the substrate and covers the bottom electrode 21, the top electrode 23 is disposed above the piezoelectric layer 22 and extends along the surface of the piezoelectric layer 22 and the surface of the substrate 1 connected to the piezoelectric layer 22 to the pad area 4, and is electrically connected to the pad area 4; the bottom electrode 21 is spaced apart from the pad area 4, and the bottom electrode 21 is spaced apart from the pressure-sensitive structure 3.

[0035] When the ultrasonic fingerprint sensor is in acoustic emission mode, the bottom electrode is grounded, and the top electrode is used to apply an excitation signal to excite the piezoelectric layer to emit ultrasonic signals. When the ultrasonic fingerprint sensor is in acoustic reception mode, the top electrode is grounded, and the bottom electrode is used to receive the voltage echo signal generated between the top and bottom electrodes when the returned ultrasonic signal acts on the piezoelectric layer. The top electrode partially overlaps with the pad area to achieve electrical signal extraction, and the bottom electrode is connected to the pad area through internal traces (not shown in the figure).

[0036] The pressure-sensitive structure is positioned around the periphery of the bottom electrode array, closer to the substrate edge than the bottom electrode array. A certain distance is maintained between the pressure-sensitive structure and the piezoelectric layer and top electrode to prevent signal crosstalk between the pressure-sensitive structure and the acoustic-electric conversion structure; this distance ranges from 2 micrometers to 50 micrometers. A protective layer covers at least the pressure-sensitive structure, and can also cover the sides of the piezoelectric layer and the top electrode to isolate the pressure-sensitive structure and the piezoelectric layer material from external environmental influences.

[0037] Compared to existing technologies, this embodiment of the invention not only incorporates an acoustic-to-electrical conversion structure but also a pressure-sensitive structure into the substrate of the ultrasonic fingerprint sensor. The pressure detection function is integrated into the fingerprint recognition function. Before triggering fingerprint recognition, the pressure detection function assists in judging false touches. Once the required pressure is determined, the acoustic-to-electrical conversion structure is triggered to collect fingerprint data, reducing the power consumption caused by frequent activation of the acoustic-to-electrical conversion structure. Furthermore, the fingerprint data collected after meeting the pressure detection requirements can improve fingerprint image quality to a certain extent, thereby accelerating fingerprint authentication efficiency and improving fingerprint recognition performance. The combination of pressure detection and fingerprint recognition is beneficial for improving fingerprint recognition effectiveness.

[0038] In addition, such as Figure 2 As shown, in this embodiment of the present invention, the pressure-sensitive structure 3 includes a pressure-sensitive material 31 and an electrode lead 32, and the electrode lead enables electrical connection to the pressure-sensitive material.

[0039] In addition, such as Figure 3 As shown, a groove 11 is provided on the lower surface of the substrate 1. The projection area of ​​the groove 11 onto the upper surface of the substrate 1 at least partially overlaps with the area where the pressure-sensitive structure is located. The groove structure on the lower surface of the substrate is more conducive to the deformation of the substrate under the influence of external forces, thereby improving the sensitivity of the pressure-sensitive structure to pressure detection. The groove on the lower surface of the substrate is specifically formed in the middle region of the substrate. The sidewall of the groove is not perpendicular to the bottom of the groove, and the bottom angle of the groove is an obtuse angle, which facilitates the bending of the substrate from the middle region where the groove is located into the groove.

[0040] In addition, such as Figure 4 As shown, the bottom electrode 21 includes: a first electrode unit 211 ( Figure 4 The square structure with dotted background shown) and the second electrode unit 212 arranged around the first electrode unit 211 ( Figure 4 The square structure shown has no background pattern; pressure-sensitive structure 3 ( Figure 4The minimum distance between the location of the rectangular structure with linear patterns shown and the edge of the substrate 1 is greater than the minimum distance between all the second electrode units 212 and the same edge. That is, the location of the pressure-sensitive structure is within the rectangular area enclosed by all the bottom electrodes. It can also be seen as replacing several second electrode units in the original second electrode unit array with pressure-sensitive structures 3 to prevent the additional pressure-sensitive structures from affecting the original fingerprint recognition function and effect of the ultrasonic fingerprint sensor. The second electrode unit is a dummy structure set up to reduce or eliminate the scattering effect of ultrasonic waves at the chip edge on fingerprint imaging. The signal generated by the dummy structure is not used for fingerprint imaging. Therefore, setting the pressure-sensitive structure in the area where the second electrode unit is located will not affect the fingerprint imaging effect and will not increase the volume of the ultrasonic fingerprint sensor. When the pressure-sensitive structure 3 is set in the area where the second electrode unit 212 is set, in order to avoid crosstalk between the acoustic-electric conversion structure 2 and the pressure-sensitive structure 3, the piezoelectric layer 22 is not set directly above the pressure-sensitive structure (e.g., Figure 4 (As shown by the dashed line area), the distance between the pressure-sensitive structure and the piezoelectric layer and top electrode must be within the range of 2 micrometers to 50 micrometers. Simultaneously, since the piezoelectric layer has an irregular shape including recessed areas, all exposed piezoelectric layers need to be covered with a protective layer to isolate them from the influence of the external environment.

[0041] In addition, the thickness of the pressure-sensitive structure is set to range from 0.1 micrometers to 5 micrometers, and the thickness of the electrode lead layer is set to range from 0.1 micrometers to 2 micrometers. The thickness of the bottom electrode is generally from 0.01 micrometers to 1 micrometer. The thickness of the pressure-sensitive structure is greater than that of the bottom electrode, which is beneficial for the pressure-sensitive structure to sense pressure.

[0042] Pressure-sensitive structures can also be formed by secondary processing using the original structure of the substrate. A wafer is set on the substrate, and a suitable wafer is selected to set the position of the pressure-sensitive structure. If the wafer is made of single-crystal silicon, a pressure-sensitive material is formed by P-type or N-type ion implantation or diffusion doping. Then, suitable electrode leads are set for the pressure-sensitive material to form a pressure-sensitive structure.

[0043] The following section details the specific parameter settings for each layer of the ultrasonic fingerprint sensor, illustrating the fabrication process of the ultrasonic fingerprint sensor:

[0044] like Figure 5As shown, a pressure-sensitive structure 3 is first fabricated on the upper surface of the wafer substrate 1. The required photoresist pattern for the pressure-sensitive structure 3 is formed through a process of coating, photolithography, and development. Then, the pressure-sensitive material 31 is fabricated onto the substrate wafer. Next, the wafer is immersed in an etching solution, and the photoresist and the pressure-sensitive material above it are removed using a lift-off process, leaving only the pressure-sensitive material in contact with the substrate surface. Commonly used pressure-sensitive materials include metals and alloys, such as nickel-chromium alloys and constantan; semiconductor materials, such as amorphous silicon and amorphous germanium; and polymer materials, such as polypyrrole and polyaniline. The thickness of the pressure-sensitive material layer is generally 0.1µm to 5µm. Optionally, for semiconductor wafer substrates such as single-crystal silicon, the pressure-sensitive material 31 can be formed in the region where the pressure-sensitive structure is located by P-type or N-type ion implantation or diffusion doping of the substrate.

[0045] Next, as follows Figure 6 As shown, the electrode leads 32 of the pressure-sensitive structure 3 are prepared on the substrate 1 by sputtering, electron beam evaporation, spraying, spin coating, or dot coating methods; the thickness of the electrode lead layer is generally 0.1 μm to 2 μm. The material of the electrode leads can be a transparent conductive material or a non-transparent conductive material. For example, at least one of the metals such as aluminum (Al), copper (Cu), gold (Au), and platinum (Pt), or inorganic conductive materials such as indium tin oxide (ITO), or organic conductive materials such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), graphite, etc., or composite conductive materials of metals and inorganic or organic materials.

[0046] Next, as follows Figure 7 As shown, the bottom electrode 21 and pads of the acoustic-electric conversion layer structure 2 are fabricated on substrate 1 by sputtering or electron beam evaporation. The thickness of the bottom electrode layer is generally 0.01 μm to 1 μm. The material of the bottom electrode 21 can be a transparent conductive material or a non-transparent conductive material. For example, at least one of the metals such as aluminum (Al), copper (Cu), gold (Au), and platinum (Pt), or it may include inorganic conductive materials such as indium tin oxide (ITO). The thickness of the pad layer is generally 1 μm to 5 μm. The material of the pads is mainly a thick-film metal, such as at least one of the metals such as aluminum (Al), copper (Cu), gold (Au), and platinum (Pt).

[0047] Next, as follows Figure 8As shown, the piezoelectric layer 22 is processed above the bottom electrode using spin coating, spray coating, slot coating, or screen printing. The thickness of the piezoelectric layer 22 is generally 5µm to 30µm. The material of the piezoelectric layer 22 can be an organic polymer material, such as PVDF and its copolymer PVDF-TRFE or blend PVDF-graphene, etc.; optionally, the material of the piezoelectric layer can also be a mixture of piezoelectric ceramic material and adhesive, such as lead zirconate titanate piezoelectric ceramics (PZT) and its alloy materials (such as lead zirconate titanate lanthanum ceramics (PLZT), lead magnesium niobate (PNZT), potassium sodium niobate (KxNa1-xNbO3, KNN), perovskite phase structure lead magnesium titanate niobate (PMN-PT)), etc., and a mixture of piezoelectric materials and adhesive; the edge of the piezoelectric layer forms a certain angle with its projection on the substrate, with the angle ranging from 0° to 90°.

[0048] Next, as follows Figure 9 As shown, the top electrode 23 is fabricated above the piezoelectric layer 22 using screen printing, sputtering, or a combination of both methods. The thickness of the top electrode 23 is typically 0.1 μm to 30 μm. The thickness of the top electrode 23 is typically from hundreds of nanometers to tens of micrometers. The material of the top electrode 23 can be a metallic material, including but not limited to Au, Ag, Cu, or Ni; it can also be a printing ink made from a mixture of epoxy resin and silver nanoparticles.

[0049] Next, as follows Figure 10 As shown, a protective layer 5 is prepared by coating, deposition, or attachment to protect the pressure-sensitive structure, top electrode, and piezoelectric layer from corrosion and rust caused by external environmental factors, thus preventing damage to the ultrasonic fingerprint sensor's imaging performance. The thickness of the protective layer 5 is typically 5µm to 40µm. The protective layer can be made of various polymers, such as optically clear adhesive (OCA), pressure-sensitive adhesive (PSA), plastics like polyimide and polyethylene terephthalate (PET), epoxy resin, or a mixture of epoxy resin and metal particles. The protective layer can be a single layer or a combination of multiple materials. After completing the protective layer process, the substrate is thinned and polished to complete the ultrasonic fingerprint sensor fabrication, ensuring the final ultrasonic fingerprint sensor chip thickness is less than 200µm.

[0050] The ultrasonic fingerprint sensor obtained through the above processing steps integrates pressure detection into the fingerprint recognition function. This pressure detection function detects external pressure, thus avoiding the impact of environmental factors such as humidity, temperature, and electromagnetic fields on the accuracy of capacitive touch detection. For example, in high humidity environments, water vapor may condense on the screen surface. The pressure created by this condensation is insufficient for pressure detection, preventing the fingerprint recognition function from being triggered and avoiding false triggering. Furthermore, since the pressure detection function is achieved through the deformation of a pressure-sensitive structure, strong electromagnetic fields will not affect the detection of this structure. These abnormal conditions will not cause the acoustic-electric conversion structure to be activated, saving system power consumption.

[0051] In addition, assisting with pressure detection during fingerprint detection can ensure the pressure of the finger pressing on the fingerprint sensor during fingerprint recognition, thereby improving the fingerprint imaging effect and speeding up the efficiency and speed of fingerprint authentication.

[0052] Another feasible embodiment of this utility model relates to an ultrasonic fingerprint detection device, including: the ultrasonic fingerprint sensor described above, and a screen or cover plate connected to the ultrasonic fingerprint sensor.

[0053] Specifically, such as Figure 11 As shown, the ultrasonic fingerprint detection device includes: an ultrasonic fingerprint sensor 10, a flexible printed circuit board (FPC) 20, a reinforcing member 30, electronic components 40, and a connector 50. The FPC is connected to the pad area 6 of the ultrasonic fingerprint sensor via low-temperature bonding, with the bonding medium including but not limited to anisotropic conductive adhesive (ACF). The electronic components include, but are not limited to, passive devices such as inductors, capacitors, and resistors, and active devices such as boost chips and signal preprocessing chips, primarily providing excitation signals to the ultrasonic fingerprint sensor and preprocessing the echo signals. The connector at the end of the FPC furthest from the ultrasonic sensor is used to connect to the main control chip of the backend system, providing communication and interaction.

[0054] The screen or cover plate 60 is fixedly connected to the ultrasonic fingerprint sensor 10 via an adhesive layer 70. The cover plate can be any suitable material capable of acoustically coupling to the ultrasonic fingerprint sensor system, such as plastic, ceramic, sapphire, metal, and glass. In addition to connecting the ultrasonic fingerprint sensor to the screen or cover plate 60, the adhesive layer 70 also enables acoustic impedance matching between the two, maximizing the efficiency of ultrasonic wave transmission.

[0055] The fixing position of the screen or cover plate 60 and the ultrasonic fingerprint sensor 10 can be divided into the following two cases, such as Figure 11 As shown, the screen or cover plate 60 is fixed to the side of the ultrasonic fingerprint sensor 10 near the substrate. Or as...Figure 12 As shown, the screen or cover plate 60 is fixed to the side of the ultrasonic fingerprint sensor 10 that is away from the substrate. When the screen or cover plate 60 is fixed to the side of the ultrasonic fingerprint sensor 10 that is away from the substrate, the lower surface of the substrate can be configured as a groove structure to increase the sensitivity of pressure detection.

[0056] In addition, such as Figure 13 As shown, the ultrasonic fingerprint detection device, from a system architecture perspective, includes an ultrasonic fingerprint sensor and external chip devices. The ultrasonic fingerprint sensor comprises a pressure detection array, an ultrasonic detection array, a storage module, a control module, and a communication module. The external chip devices include a power supply chip, an interface chip, a processor chip, and a storage chip. The control module of the ultrasonic fingerprint sensor can configure the pressure detection array and the ultrasonic detection array to transmit and receive signals and store data in the storage module. The sensor's communication module sends the data from the storage module to the external interface chip. The interface chip is responsible for communicating with the sensor chip and transmitting the sensor data to the external processor chip for processing, such as fingerprint image reconstruction and feature extraction. The external power supply chip primarily powers the ultrasonic fingerprint sensor, and the storage chip can temporarily or permanently store pressure detection data and ultrasonic fingerprint detection data.

[0057] Compared with related technologies, the ultrasonic fingerprint detection device provided in this embodiment of the present invention is equipped with the ultrasonic fingerprint sensor provided in the aforementioned embodiment. Therefore, it also has the technical effects provided in the aforementioned embodiment, has better performance, and can better realize the ultrasonic fingerprint function.

[0058] Another feasible embodiment of this utility model relates to an electronic device, including: the ultrasonic fingerprint sensor described above or the ultrasonic fingerprint detection device described above.

[0059] Compared with related technologies, the electronic device provided in this embodiment of the present invention is equipped with the ultrasonic fingerprint sensor or ultrasonic fingerprint detection device provided in the aforementioned embodiments. Therefore, it also has the technical effects provided in the aforementioned embodiments, which will not be elaborated here.

[0060] The following describes the application of fingerprint recognition using the electronic device, ultrasonic fingerprint sensor, or ultrasonic fingerprint detection device proposed in this utility model:

[0061] like Figure 14As shown, in the initial stage, the system first detects a touch action, such as through a capacitive touch panel on the screen or cover. At this time, the ultrasonic fingerprint sensor is configured to operate in non-ultrasonic mode, using only the pressure-sensitive structure to detect the force of a finger or other object pressed on the device. The sensor compares the measured static force F with a set threshold value. In this example, the threshold is numbered 1 and can be 10 grams of force (gf); the threshold setting depends on the specific sensor, device, and / or user. When the detected static force value is greater than or equal to threshold 1, the system determines that a finger is detected and can activate the sensor's ultrasonic detection array (acousto-electric conversion structure) to prepare for ultrasonic imaging of the fingerprint. When the measured static force is less than the threshold level, the sensor continues to operate in non-ultrasonic mode. When a finger is detected and the ultrasonic detection array is activated, the pressure detection array continues to operate, measuring the static force of the finger pressing and comparing the measured static force F with threshold 2. Threshold 2 can be called the minimum imaging threshold, which is the minimum static force required to perform ultrasonic fingerprint imaging and achieve the required authentication effect. In this example, threshold 2 can be 40 gf. If the detected static force is less than the minimum imaging threshold, the system can return to the initial stage to determine if the finger has been lifted; otherwise, it provides a prompt to the user. The prompt can be a screen message or tactile feedback from the motor. When the detected finger force is greater than or equal to the minimum imaging threshold, the ultrasonic fingerprint sensor completes fingerprint imaging of the user's finger. The acquired fingerprint image data is transmitted to an external processor chip to perform the user authentication process. In some implementations, the pressure applied by the finger can be measured during the user's new device fingerprint registration process, and the measured pressure value can be correlated with the fingerprint image. In subsequent authentication processes, a retrieval method can be used to compare the finger pressure value during the imaging process with the finger pressure stored during device fingerprint registration. For example, if a finger pressure of 60 gf is detected during ultrasonic fingerprint imaging, a registration template with a finger pressure close to 60 gf can be used in subsequent authentication processes to verify that the user is a registered user. Generally, finger pressure tends to stabilize for a period of time after adulthood. Since different people apply varying degrees of pressure, in some implementation cases, the pressure value can be used as an auxiliary feature to enhance the anti-counterfeiting effect of fingerprint authentication.

[0062] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the present invention.

Claims

1. An ultrasonic fingerprint sensor, characterized in that, include: Substrate, pad area, acoustic-electric conversion structure, pressure-sensitive structure, and protective layer; Both the acoustic-electric conversion structure and the pad area are disposed on the upper surface of the substrate, and the acoustic-electric conversion structure is electrically connected to the pad area. The pressure-sensitive structure is disposed on the upper surface of the substrate, and the pressure-sensitive structure is spaced apart from the acoustic-electric conversion structure. The protective layer covers at least the pressure-sensitive structure. When the ultrasonic fingerprint sensor is subjected to external pressure, the substrate deforms, causing the pressure-sensitive structure to deform as well.

2. The ultrasonic fingerprint sensor according to claim 1, characterized in that, The lower surface of the substrate is provided with a groove, and the projection area of ​​the groove toward the upper surface of the substrate at least partially overlaps with the area where the pressure-sensitive structure is set.

3. The ultrasonic fingerprint sensor according to claim 1, characterized in that, The acoustic-electric conversion structure includes: a bottom electrode, a piezoelectric layer, and a top electrode; The bottom electrode is disposed on the upper surface of the substrate, the piezoelectric layer is disposed above the substrate and covers the bottom electrode, and the top electrode is disposed above the piezoelectric layer and extends along the surface of the piezoelectric layer and the substrate surface in contact with the piezoelectric layer to the pad area, and is electrically connected to the pad area. The bottom electrode is spaced apart from the pad area, and the bottom electrode is also spaced apart from the pressure-sensitive structure.

4. The ultrasonic fingerprint sensor according to claim 3, characterized in that, The bottom electrode includes: a first electrode unit and a second electrode unit disposed around the first electrode unit; The minimum distance between the location of the pressure-sensitive structure and the edge of the substrate is greater than the minimum distance between all the second electrode units and the same edge.

5. The ultrasonic fingerprint sensor according to claim 1, characterized in that, The thickness of the pressure-sensitive structure is set to range from 0.1 micrometers to 5 micrometers.

6. The ultrasonic fingerprint sensor according to claim 1, characterized in that, A wafer is disposed at the location of the pressure-sensitive structure on the substrate. When the wafer is made of single-crystal silicon, the pressure-sensitive structure is formed by ion implantation or diffusion doping of the wafer.

7. The ultrasonic fingerprint sensor according to any one of claims 1 to 6, characterized in that, The distance between the pressure-sensitive structure and the acoustic-electric conversion structure is set to be between 2 micrometers and 50 micrometers.

8. An ultrasonic fingerprint detection device, characterized in that, include: The ultrasonic fingerprint sensor as described in any one of claims 1 to 7, and the screen or cover plate connected to the ultrasonic fingerprint sensor.

9. The ultrasonic fingerprint detection device according to claim 8, characterized in that, The screen or cover plate is fixed to the side of the ultrasonic fingerprint sensor closest to the substrate, or the screen or cover plate is fixed to the side of the ultrasonic fingerprint sensor furthest from the substrate.

10. An electronic device, characterized in that, include: The ultrasonic fingerprint sensor as described in any one of claims 1 to 7, or the ultrasonic fingerprint detection device as described in claim 8 or 9.

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