Ultrasonic fingerprint sensor chip and electronic device

Abstract

Provided in the embodiments of the present application are an ultrasonic fingerprint sensor chip and an electronic device. The ultrasonic fingerprint sensor chip comprises: a silicon substrate, and a lower electrode, a piezoelectric layer, an upper electrode, an isolation layer and upper electrode driving signal traces, which are arranged on the silicon substrate, wherein the piezoelectric layer is located between the lower electrode and the upper electrode; the edge of the upper electrode that is close to first ends of the upper electrode driving signal traces extends beyond the edge of a first end of the piezoelectric layer, so as to form an overhang region; the isolation layer is located between the first end of the piezoelectric layer and the upper electrode driving signal traces and below the upper electrode, and the isolation layer at least covers the overhang region; the edge of a first end of the upper electrode is further provided with interconnection contacts, which are electrically connected to the upper electrode driving signal traces; and the upper electrode driving signal traces are used for transmitting a driving signal of the upper electrode, and the driving signal is used for controlling the piezoelectric layer to emit an ultrasonic signal. An isolation layer is provided, such that the stability and quality of ultrasonic signal transmission performed by an ultrasonic fingerprint sensor chip are improved.

Description

Ultrasonic fingerprint sensor chips and electronic devices Technical Field

[0001] This application relates to the field of fingerprint recognition technology, and more particularly to an ultrasonic fingerprint sensor chip and electronic device. Background Technology

[0002] With the development of electronic devices, fingerprint recognition functionality is becoming increasingly common. Among these, ultrasonic fingerprint sensors construct a fingerprint image by emitting ultrasonic signals onto the finger surface and receiving the echo signals, thus achieving fingerprint recognition. Ultrasonic fingerprint sensors offer high fingerprint recognition capabilities, applicability, and integration, leading to their increasingly widespread application.

[0003] Since ultrasonic fingerprint sensors construct fingerprint images by emitting ultrasonic signals and receiving echo signals, the stability and quality of the emitted ultrasonic signals are crucial. Therefore, eliminating fluctuations in the emitted ultrasonic signals and improving their stability and quality has become an urgent technical problem to be solved. Summary of the Invention

[0004] In view of this, embodiments of this application provide an ultrasonic fingerprint sensor chip and an electronic device, which improves the stability and quality of ultrasonic signals emitted by the ultrasonic fingerprint sensor chip.

[0005] In a first aspect, an ultrasonic fingerprint sensor chip is provided, comprising: a silicon substrate, a lower electrode, a piezoelectric layer, an upper electrode, an isolation layer, and an upper electrode driving signal trace disposed on the silicon substrate; the piezoelectric layer is located between the lower electrode and the upper electrode, and the edge of the upper electrode near the first end of the upper electrode driving signal trace extends beyond the edge of the first end of the piezoelectric layer to form an overhang region; the isolation layer is located between the first end of the piezoelectric layer and the upper electrode driving signal trace and is located below the upper electrode, and the isolation layer at least covers the overhang region; an interconnection contact is further disposed on the edge of the first end of the upper electrode, and the interconnection contact is electrically connected to the upper electrode driving signal trace; the upper electrode driving signal trace is used to transmit a driving signal of the upper electrode, and the driving signal is used to control the piezoelectric layer to emit an ultrasonic signal.

[0006] In a second aspect, an electronic device is provided, including the ultrasonic fingerprint sensor chip provided in the first aspect of this application.

[0007] In the embodiment of this application, the ultrasonic fingerprint sensor chip includes a silicon substrate and a lower electrode, a piezoelectric layer, an upper electrode, an isolation layer, and an upper electrode drive signal trace disposed on the silicon substrate. The piezoelectric layer is located between the lower electrode and the upper electrode. An interconnecting contact is provided on the edge of the first end of the upper electrode, and the interconnecting contact is electrically connected to the upper electrode drive signal trace. The first end of the upper electrode and the first end of the piezoelectric layer are close to the upper electrode drive signal trace. The edge of the first end of the upper electrode extends beyond the edge of the first end of the piezoelectric layer, forming an overhang region. That is, the upper electrode directly crosses from the piezoelectric layer to the isolation layer. The junction edge between the upper electrode and the piezoelectric layer is flat and uniform. The upper electrode crosses the piezoelectric layer and is then electrically connected to the upper electrode drive signal trace through the interconnecting contact. When a drive signal is applied to the upper electrode, the piezoelectric layer generates an ultrasonic signal. Because the junction edge between the upper electrode and the piezoelectric layer is flat and uniform, the piezoelectric layer generates a uniform ultrasonic signal at the junction edge of the piezoelectric layer and the upper electrode without signal fluctuation. Although the upper electrode is connected to the upper electrode drive signal trace through interconnecting contacts, there is an isolation layer below the interconnecting contacts that does not have piezoelectric properties. Therefore, it will not generate ultrasonic signals, thereby eliminating the fluctuation of ultrasonic signals and improving the stability and quality of ultrasonic signals emitted by the ultrasonic fingerprint sensor chip. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0009] Figure 1 is an application scenario diagram of the ultrasonic fingerprint sensor chip provided in the embodiment of this application;

[0010] Figure 2A is a top view of an ultrasonic fingerprint sensor chip provided by related technologies;

[0011] Figure 2B is an enlarged schematic diagram of the first end of the upper electrode and the first end of the piezoelectric layer in Figure 2A;

[0012] Figure 2C is a cross-sectional view along the AA' direction in Figure 2A;

[0013] Figure 2D is a schematic diagram of an imaging of the ultrasonic waves emitted by the ultrasonic fingerprint sensor chip shown in Figure 2A.

[0014] Figure 3A is a top view of an ultrasonic fingerprint sensor chip provided in an embodiment of this application;

[0015] Figure 3B is an enlarged schematic diagram of the first end of the upper electrode and the first end of the piezoelectric layer in Figure 3A;

[0016] Figure 3C is a cross-sectional view along the AA' direction in Figure 3A;

[0017] Figure 4A is a top view of an ultrasonic fingerprint sensor chip provided in an embodiment of this application;

[0018] Figure 4B is an enlarged schematic diagram of the first end of the upper electrode and the first end of the piezoelectric layer in Figure 4A;

[0019] Figure 4C is a cross-sectional view along the AA' direction in Figure 4A;

[0020] Figure 4D is another cross-sectional view along the AA' direction in Figure 4A;

[0021] Figure 5A is a top view of an ultrasonic fingerprint sensor chip provided in an embodiment of this application;

[0022] Figure 5B is an enlarged schematic diagram of the first end of the upper electrode and the first end of the piezoelectric layer in Figure 5A.

[0023] Figure 5C is a cross-sectional view along the AA' direction in Figure 5A;

[0024] Figure 6 is a structural diagram of an electronic device provided in an embodiment of this application.

[0025] Explanation of reference numerals in the attached figures: 11: Silicon substrate; 12: Piezoelectric layer; 13: Upper electrode; 14: Lower electrode; 15: Upper electrode drive signal trace; 16: Passivation layer; 17: PAD; 18: Interconnect contact; 19: Protective layer; 21: First region; 22: Second region; 23: Exceeding region; 31: Gold finger; 41: Shielding metal layer; 42: Shielding metal layer; 51: Isolation layer; 80: Display screen; 100: Ultrasonic fingerprint sensor chip; 121: First end of the piezoelectric layer; 131: First end of the upper electrode; 161: Passivation layer window; 200: Ultrasonic fingerprint sensor chip. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of this application.

[0027] It should be noted that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" used in the embodiments of this application indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0028] The technical solutions provided in this application are applied to ultrasonic fingerprint sensor chips and devices and equipment using ultrasonic fingerprint sensor chips. This application does not limit the names and types of the devices and equipment. For example, a device using an ultrasonic fingerprint sensor chip can be called an electronic device, a terminal device, a communication device, etc. For example, electronic devices include, but are not limited to, mobile phones, tablets, smartwatches, smart bracelets, etc.

[0029] For example, Figure 1 is an application scenario diagram of the ultrasonic fingerprint sensor chip provided in the embodiment of this application, showing a scenario where a user unlocks a mobile phone with their fingerprint. As shown in Figure 1, the mobile phone includes a display screen 80 and an ultrasonic fingerprint sensor chip 100 disposed below the display screen 80. When the user's finger 86 is placed in the fingerprint recognition area in the display screen 80, the ultrasonic fingerprint sensor chip 100 can generate an ultrasonic signal 81 and detect the echo signal 83 of the ultrasonic fingerprint signal 81 to perform fingerprint recognition of the user.

[0030] The following describes one implementation of an ultrasonic fingerprint sensor chip with reference to Figures 2A to 2C. Figure 2A is a top view of an ultrasonic fingerprint sensor chip provided by related technology, Figure 2B is an enlarged schematic diagram of the first end of the upper electrode and the first end of the piezoelectric layer in Figure 2A, and Figure 2C is a cross-sectional view along the AA' direction in Figure 2A.

[0031] As shown in Figures 2A and 2C, the ultrasonic fingerprint sensor chip 100 includes: a silicon substrate 11, a lower electrode 14, a piezoelectric layer 12, an upper electrode 13, and an upper electrode drive signal trace 15 disposed on the silicon substrate 11.

[0032] The piezoelectric layer 12 is located between the lower electrode 14 and the upper electrode 13. The edge of the upper electrode 13 near the first end of the upper electrode drive signal line 15 is located within the edge of the first end 121 of the piezoelectric layer. An interconnecting contact 18 is also provided on the edge of the first end 131 of the upper electrode, and the interconnecting contact 18 is electrically connected to the upper electrode drive signal line 15.

[0033] The upper electrode drive signal trace 15 is used to transmit the drive signal of the upper electrode 13. The drive signal is used to control the piezoelectric layer 12 to emit ultrasonic signals.

[0034] The working principle of an ultrasonic fingerprint sensor chip is as follows: it constructs a fingerprint image by emitting ultrasonic signals to the surface of the finger and receiving the echo signals, thereby achieving fingerprint recognition. Specifically, as shown in Figure 2C, the ultrasonic fingerprint sensor chip includes a piezoelectric layer 12 formed of piezoelectric material. The piezoelectric layer 12 typically has two electrodes, referred to as the upper electrode 13 and the lower electrode 14. The upper electrode 13 and the lower electrode 14 are used to apply an electric field, causing the piezoelectric layer 12 to generate the inverse piezoelectric effect, converting electrical energy into mechanical oscillation and emitting ultrasonic signals. When the ultrasonic signal encounters the fingerprint on the surface of the finger, the ultrasonic signal is reflected back to form an echo signal, which is received by the ultrasonic fingerprint sensor chip. The ultrasonic fingerprint sensor chip then converts the echo signal back into an electrical signal, utilizing the density difference between the skin and air on the fingerprint surface to construct a fingerprint image. This application focuses on the technical principle and related structure of ultrasonic transmission.

[0035] In this context, piezoelectricity is referred to as piezoelectricity or piezoelectric effect. The piezoelectric layer is formed from a piezoelectric material, which possesses piezoelectric properties. This application does not limit the piezoelectric material used in the piezoelectric layer. For example, piezoelectric materials include quartz. The piezoelectric property refers to the phenomenon that certain crystals generate voltage when subjected to external pressure, and conversely, if voltage exists on both sides of a crystal, the crystal shape will slightly deform. Specifically, when a crystal is subjected to pressure, its shape changes, and the distance between some atoms becomes closer or farther, disrupting the original balance and resulting in a net electrical charge. Positive and negative charges appear on the crystal surface; this phenomenon is called the piezoelectric effect. Conversely, when a voltage is applied across the crystal, the atoms experience electrical pressure. To maintain charge balance, the atoms vibrate back and forth, causing a slight deformation in the shape of the piezoelectric crystal; this phenomenon is called the reverse-piezoelectric effect.

[0036] In this implementation, as shown in Figures 2A and 2C, the upper electrode drive signal trace 15 is used to transmit the drive signal of the upper electrode 13, which is applied to the upper electrode 13. The drive signal of the upper electrode 13 is an AC signal. Optionally, the drive signal of the upper electrode 13 is a pulse signal. The lower electrode 14 also needs to have its own drive signal applied. This application does not limit the generation and transmission method of the drive signal of the lower electrode 14. When corresponding drive signals are applied to both the upper electrode 13 and the lower electrode 14, the piezoelectric layer 12 generates an inverse piezoelectric effect, thereby emitting an ultrasonic signal.

[0037] As shown in Figures 2A and 2B, structurally, the upper electrode 13 is located above the piezoelectric layer 12. The end of the upper electrode 13 closest to the upper electrode drive signal trace 15 is called the first end 131 of the upper electrode, and the end of the piezoelectric layer 12 closest to the upper electrode drive signal trace 15 is called the first end 121 of the piezoelectric layer. An interconnecting contact 18 is provided along the edge of the first end 131 of the upper electrode. The interconnecting contact 18 is electrically connected to the upper electrode drive signal trace 15 and is used to receive the drive signal from the upper electrode 13. As shown in Figure 2B, the edge of the first end 131 of the upper electrode is located within the edge of the first end 121 of the piezoelectric layer. Therefore, the interconnecting contact 18 needs to cross the piezoelectric layer 12 to be electrically connected to the upper electrode drive signal trace 15, thus forming a first region 21 and a second region 22 at the first end 121 of the piezoelectric layer. The first region 21 is the overlapping area of ​​the upper electrode 13 and the piezoelectric layer 12 when the interconnecting contact 18 crosses the piezoelectric layer 12. The interconnecting contact 18, or the upper electrode 13, covers the upper region 21. However, the upper electrode 13 does not cover the upper region 22. Therefore, when the upper electrode 13 and the lower electrode 14 are given corresponding driving signals, there is voltage above and below the first region 21, while there is no driving signal for the upper electrode 13 above the second region 22. According to the principle of emitting ultrasonic signals described above, the piezoelectric layer 12 will emit ultrasonic signals in the first region 21, but will not emit ultrasonic signals in the second region 22.

[0038] For example, Figure 2D is a schematic diagram of an imaging of the ultrasonic waves emitted by the ultrasonic fingerprint sensor chip shown in Figure 2A. Referring to Figures 2B and 2D, when the ultrasonic fingerprint sensor chip emits an ultrasonic signal after startup, an imaging image is obtained, showing obvious diffraction ripples near the first region.

[0039] As can be seen, for the ultrasonic fingerprint sensor chip shown in Figures 2A-2C, since the edge of the first end 131 of the upper electrode is located inside the edge of the first end 121 of the piezoelectric layer, and the edge of the first end 131 of the upper electrode is provided with interconnecting contacts 18 for electrical connection with the upper electrode drive signal trace 15, the edge shape of the overlapping area of ​​the first end 121 of the piezoelectric layer and the first end 131 of the upper electrode is not smooth, and there is an edge abrupt change at the position of the first region. Thus, when the ultrasonic fingerprint sensor chip is working, because there is an upper electrode 13 above the first region on the piezoelectric layer 12, diffraction acoustic patterns are generated near the first region, and the emitted ultrasonic signal fluctuates, resulting in low stability and quality of the emitted ultrasonic signal.

[0040] It should be noted that the ultrasonic fingerprint sensor chip may also include other structures. This application does not limit the other structures included in the ultrasonic fingerprint sensor chip or the materials used in each structure.

[0041] The upper electrode 13 is made of metal. Optionally, the upper electrode 13 is a silver paste electrode. The silver paste electrode uses silver paste as a conductive material and is formed through processes such as printing and spraying. The silver paste is formulated from silver or its compounds, flux, binder, and diluent, etc. This application does not limit the composition ratio of the silver paste or the formation method of the silver paste electrode.

[0042] Optionally, as shown in Figure 2C, the ultrasonic fingerprint sensor chip further includes a shielding metal layer. Optionally, the shielding metal layer is located below the piezoelectric layer 12.

[0043] The principle of shielding typically involves enclosing the area or circuit to be protected using a shield made of metal material. This controls the propagation of electric fields, magnetic fields, and electromagnetic waves, thereby preventing external electromagnetic fields from interfering with internal circuits and vice versa. It is understood that ultrasonic fingerprint sensor chips have a multi-layered structure, with different functional circuits set up at different levels to achieve different functions. This application does not limit the function or structure of these functional circuits. By setting a shielding metal layer, external interference signals such as electromagnetic waves, static electricity, and electron beam interference can be shielded, ensuring the normal operation of the functional circuits within the ultrasonic fingerprint sensor chip, thus ensuring the normal operation of the ultrasonic fingerprint sensor chip. Furthermore, the shielding metal layer also serves to conduct heat and dissipate heat, preventing the ultrasonic fingerprint sensor chip from being damaged due to high temperatures.

[0044] Optionally, the shielding metal layer is the top metal in the ultrasonic fingerprint sensor chip.

[0045] Optionally, the silicon substrate 11 also includes power traces and ground traces, with the shielding metal layer connected to the power traces or electrically connected to the ground traces.

[0046] Optionally, as shown in Figure 2C, the ultrasonic fingerprint sensor chip also includes a passivation layer 16. The passivation layer 16 is located below the first end 121 of the piezoelectric layer and the interconnecting contact 18 on the upper electrode 13. A window is formed in the passivation layer 16 at the position corresponding to the interconnecting contact 18, forming a passivation layer window 161. The interconnecting contact 18 passes through the passivation layer window 161 and is electrically connected to the driving signal of the upper electrode 13.

[0047] By setting the passivation layer 16, electrical isolation between different metal structures in the top layer of the silicon substrate 11 is achieved. At the same time, a protective film is provided for the top metal of the silicon substrate 11 to prevent the metal from being corroded or oxidized, and to block dust, thereby improving the security, reliability and service life of the ultrasonic fingerprint sensor chip.

[0048] Optionally, as shown in Figure 2C, the ultrasonic fingerprint sensor chip also includes a protective layer 19. The protective layer 19 covers the upper surface of the upper electrode 13.

[0049] By setting the protective layer 19, the upper electrode 13 is protected from oxidation and other problems. In addition, the protective layer 19 can also protect the piezoelectric layer 12 to ensure its piezoelectric performance and avoid the penetration and failure behavior of the piezoelectric layer 12 and the upper electrode 13 under high temperature, high humidity and other conditions, thereby improving the security, reliability and service life of the ultrasonic fingerprint sensor chip.

[0050] Optionally, as shown in Figure 2C, the ultrasonic fingerprint sensor chip also includes a PAD17. Optionally, the PAD17 is electrically connected to the upper electrode drive signal trace 15.

[0051] PAD stands for pad, used to provide circuit connection points for the ultrasonic fingerprint sensor chip, enabling electrical connections between the chip and external circuit structures. For example, the ultrasonic fingerprint sensor chip can be electrically connected to the gold finger 31, a flexible printed circuit (FPC), etc., via PAD17. The ultrasonic fingerprint sensor chip can then transmit the detected fingerprint image signal to other components in the electronic device, such as a processor, via the gold finger 31 or the flexible circuit board.

[0052] In summary, the ultrasonic fingerprint sensor chips shown in Figures 2A to 2C have the problem of fluctuations when emitting ultrasonic waves.

[0053] This application provides an ultrasonic fingerprint sensor chip. By designing the edge shape of the upper electrode crossing the piezoelectric layer to be flat, and setting an isolation layer between the piezoelectric layer, the upper electrode, and the upper electrode drive signal trace, fluctuations in the emitted ultrasonic signal are avoided, improving the stability and quality of the ultrasonic signal emitted by the ultrasonic fingerprint sensor chip during operation, thereby improving the fingerprint recognition effect of the ultrasonic fingerprint sensor chip.

[0054] The specific implementation of the embodiments of this application will be further described below with reference to the accompanying drawings.

[0055] It should be noted that the features in the various embodiments of this application can be combined with each other, and the same features and effects can be referred to each other.

[0056] Figure 3A is a top view of an ultrasonic fingerprint sensor chip provided in an embodiment of this application; Figure 3B is an enlarged schematic diagram of the first end of the upper electrode and the first end of the piezoelectric layer in Figure 3A; and Figure 3C is a cross-sectional view along the AA' direction in Figure 3A. As shown in Figures 3A to 3C, the ultrasonic fingerprint sensor chip provided in this embodiment includes:

[0057] A silicon substrate 11, a lower electrode 14, a piezoelectric layer 12, an upper electrode 13, an isolation layer 51, and an upper electrode drive signal trace 15 disposed on the silicon substrate 11.

[0058] The piezoelectric layer 12 is located between the lower electrode 14 and the upper electrode 13. The edge of the upper electrode 13 near the first end of the upper electrode drive signal line 15 extends beyond the edge of the first end 121 of the piezoelectric layer to form an overhang region 23. The isolation layer 51 is located between the first end 121 of the piezoelectric layer and the upper electrode drive signal line 15 and is located below the upper electrode 13. The isolation layer 51 at least covers the overhang region 23.

[0059] An interconnecting contact 18 is also provided on the edge of the first end 131 of the upper electrode, and the interconnecting contact 18 is electrically connected to the upper electrode drive signal line 15.

[0060] The upper electrode drive signal trace 15 is used to transmit the drive signal of the upper electrode 13. The drive signal is used to control the piezoelectric layer 12 to emit ultrasonic signals.

[0061] The ultrasonic fingerprint sensor chip provided in this embodiment, as shown in Figure 3C, has a piezoelectric layer 12 located between the upper electrode 13 and the lower electrode 14. For ease of explanation, the end of the upper electrode 13 closest to the upper electrode drive signal trace 15 is referred to as the first end 131 of the upper electrode, and the end of the piezoelectric layer 12 closest to the upper electrode drive signal trace 15 is referred to as the first end 121 of the piezoelectric layer. The end of the upper electrode drive signal trace 15 closest to both the upper electrode 13 and the piezoelectric layer 12 is referred to as the first end of the upper electrode drive signal trace 15. That is, the first end 131 of the upper electrode, the first end 121 of the piezoelectric layer, and the first end of the upper electrode drive signal trace 15 are close to each other. An interconnecting contact 18 is provided on the edge of the first end 131 of the upper electrode, and the interconnecting contact 18 is electrically connected to the upper electrode drive signal trace 15 to receive the drive signal from the upper electrode 13.

[0062] Compared to the ultrasonic fingerprint sensor chip shown in Figures 2A-2C, the ultrasonic fingerprint sensor chip provided in this embodiment further includes an isolation layer 51. The isolation layer 51 is located between the first end 121 of the piezoelectric layer and the upper electrode drive signal trace 15, and is located below the upper electrode 13. The isolation layer 51 is formed of an insulating material. Moreover, the isolation layer 51 does not possess piezoelectric properties, or the piezoelectric coefficient of the isolation layer 51 is much smaller than the piezoelectric coefficient of the piezoelectric layer 12. The piezoelectric coefficient is an important indicator for evaluating the strength of the piezoelectric properties of a piezoelectric material. The piezoelectric coefficient can be expressed or calculated in various ways, and this embodiment does not limit this. For example, the piezoelectric coefficient can be a piezoelectric constant d. Generally, the smaller the piezoelectric coefficient, the weaker the piezoelectric properties of the piezoelectric material, or even that it does not possess piezoelectric properties. When the piezoelectric coefficient of the isolation layer 51 is much smaller than that of the piezoelectric layer 12, when the upper electrode 13 and the lower electrode 14 are respectively applied with corresponding driving signals, even if part of the isolation layer 51 covers the upper electrode 13, and even if the isolation layer 51 generates a very weak ultrasonic signal, it will not cause fluctuations in the ultrasonic signal generated by the piezoelectric layer 12, so the influence on the piezoelectric layer 12 can be ignored. When the isolation layer 51 does not have piezoelectric properties, when the upper electrode 13 and the lower electrode 14 are respectively applied with corresponding driving signals, even if part of the isolation layer 51 covers the upper electrode 13, the isolation layer 51 will still not generate an ultrasonic signal.

[0063] Optionally, the isolation layer 51 is made of plastic. Plastic materials do not have piezoelectric properties; therefore, the isolation layer 51 formed of plastic material will not generate ultrasonic signals and thus will not cause fluctuations in the ultrasonic signals emitted by the ultrasonic fingerprint sensor chip.

[0064] Optional, the plastic material includes polyimide (PI) material.

[0065] Optionally, the ratio of the piezoelectric coefficient of the isolation layer 51 to that of the piezoelectric layer 12 is less than 1 / 5.

[0066] For ease of explanation, the end of the isolation layer 51 closest to the piezoelectric layer 12 is referred to as the first end of the isolation layer 51, and the end of the isolation layer 51 closest to the upper electrode drive signal trace 15 is referred to as the second end of the isolation layer 51. The isolation layer 51 is located between the first end 121 of the piezoelectric layer and the upper electrode drive signal trace 15. Optionally, the side face of the first end of the isolation layer 51 is adjacent to the side face of the first end 121 of the piezoelectric layer (see the structure shown in Figure 4C or Figure 4D later), or the first end of the isolation layer 51 and the first end 121 of the piezoelectric layer have an overlapping area (see the structure shown in Figure 5C later). For example, the first end of the isolation layer 51 can be extended into the bottom of the first end 121 of the piezoelectric layer. It should be noted that the planar shape of the isolation layer 51 is not limited in this embodiment.

[0067] As shown in Figures 3A and 3B, the edge of the first end 131 of the upper electrode extends beyond the edge of the first end 121 of the piezoelectric layer, forming an overhang region 23. Thus, the junction edge of the first end 131 of the upper electrode and the first end 121 of the piezoelectric layer is the edge of the first end 121 of the piezoelectric layer. This junction edge is flat and uniform, ensuring that the piezoelectric layer 12 generates a uniform ultrasonic signal at the junction edge. An interconnecting contact 18 is also provided on the edge of the first end 131 of the upper electrode, which electrically connects to the upper electrode drive signal trace 15 across the isolation layer 51. Because the isolation layer 51 has weak or no piezoelectric characteristics, it does not generate ultrasonic signals, or in other words, the weak ultrasonic signals it generates do not affect the ultrasonic signals generated by the piezoelectric layer 12. Therefore, the piezoelectric layer 12 can generate a uniform ultrasonic signal, improving the stability and quality of the ultrasonic signals emitted by the piezoelectric layer 12.

[0068] As can be seen, the ultrasonic fingerprint sensor chip provided in this embodiment includes a silicon substrate and a lower electrode, a piezoelectric layer, an upper electrode, an isolation layer, and an upper electrode drive signal trace disposed on the silicon substrate. The piezoelectric layer is located between the lower electrode and the upper electrode. A protruding interconnect contact is provided on the edge of the first end of the upper electrode, and the interconnect contact is electrically connected to the upper electrode drive signal trace. The first end of the upper electrode and the first end of the piezoelectric layer are close to the upper electrode drive signal trace. The edge of the first end of the upper electrode extends beyond the edge of the first end of the piezoelectric layer, forming an overhang region. That is, the upper electrode directly crosses from the piezoelectric layer to the isolation layer. The junction edge between the upper electrode and the piezoelectric layer is flat and uniform. The upper electrode crosses the piezoelectric layer and then is electrically connected to the upper electrode drive signal trace through the interconnect contact. When a drive signal is applied to the upper electrode, the piezoelectric layer will generate an ultrasonic signal. Because the junction edge between the upper electrode and the piezoelectric layer is flat and uniform, the piezoelectric layer generates a uniform ultrasonic signal at the junction edge of the piezoelectric layer and the upper electrode without signal fluctuation. Although the upper electrode is connected to the upper electrode drive signal trace through interconnecting contacts, there is an isolation layer below the interconnecting contacts that does not have piezoelectric properties. Therefore, it will not generate ultrasonic signals, thereby eliminating the fluctuation of ultrasonic signals and improving the stability and quality of ultrasonic signals emitted by the ultrasonic fingerprint sensor chip.

[0069] Optionally, the thickness of the isolation layer 51 is less than the thickness of the piezoelectric layer 12. Optionally, the thickness of the isolation layer 51 is less than 10 μm. Referring to Figure 3C, by setting the thickness of the isolation layer 51 to be less than the thickness of the piezoelectric layer 12, the upper surface of the isolation layer 51 may be lower than the upper surface of the piezoelectric layer 12, which reduces the process difficulty of the upper electrode 13 crossing the edge of the first end 121 of the piezoelectric layer and is easier to implement.

[0070] Optionally, the thickness of the insulating layer 51 is less than the sum of the thickness of the piezoelectric layer 12 and the first thickness of the upper electrode 13. The first thickness is the thickness of the upper electrode 13 at locations other than those exceeding region 23 and interconnecting contact 18. Optionally, the first thickness is between 10 μm and 40 μm. Referring to Figure 3C, since the thickness of the insulating layer 51 is less than the sum of the thickness of the piezoelectric layer 12 and the first thickness of the upper electrode 13, the upper surface of the insulating layer 51 may be lower than the upper surface of the piezoelectric layer 12, or the upper surface of the insulating layer 51 may be higher than the upper surface of the piezoelectric layer 12, but the upper surface of the insulating layer 51 must be lower than the upper surface of the upper electrode 13. This ensures that the upper electrode 13 can completely span the edge of the first end 121 of the piezoelectric layer, making the implementation more flexible.

[0071] It should be noted that the ultrasonic fingerprint sensor chip may also include other structures. This application does not limit the other structures included in the ultrasonic fingerprint sensor chip or the materials used in each structure.

[0072] The upper electrode 13 and the lower electrode 14 are typically made of conductive materials, such as metals or conductive polymers. The conductive material is processed onto the surface of the piezoelectric material through chemical deposition, physical vapor deposition, or other processes to form a good electrode-piezoelectric material interface and a stable electrode connection, thereby improving the stability and quality of the ultrasonic signals emitted by the piezoelectric layer 12.

[0073] Optionally, the upper electrode 13 can be a silver paste electrode.

[0074] Optionally, as shown in Figure 3C, the ultrasonic fingerprint sensor chip may also include a shielding metal layer, a passivation layer (not shown), a protective layer 19, and a PAD 17. A passivation layer window 161 is formed in the passivation layer at the position corresponding to the interconnection contact 18. The interconnection contact 18 passes through the passivation layer window and is electrically connected to the upper electrode 13 driving signal. Please refer to the relevant descriptions in Figures 2A to 2C above, which will not be repeated here.

[0075] Optionally, a shielding metal layer (not shown) may be provided below the isolation layer 51.

[0076] The ultrasonic fingerprint sensor chip has a multi-layer structure, and different functional circuits can be set in different layers to implement different functions. This application does not limit the function and structure of the functional circuits. By setting a shielding metal layer below the isolation layer 51, interference shielding is provided for the functional circuits below the upper electrode 13, ensuring the normal operation of the functional circuits below the upper electrode 13, and thus ensuring the normal operation of the ultrasonic fingerprint sensor chip.

[0077] Optionally, the edge of the first end 121 of the piezoelectric layer is located between the two ends of the shielding metal layer disposed below the isolation layer 51.

[0078] In this implementation, since the upper electrode 13 completely covers the edge of the first end 121 of the piezoelectric layer, and the shielding metal layer below the isolation layer 51 at least covers the edge of the first end 121 of the piezoelectric layer, it plays an interference shielding role for the functional circuits located near the edge of the first end 121 of the piezoelectric layer in the ultrasonic fingerprint sensor chip, so that the functional circuits can work normally, thereby ensuring the normal operation of the ultrasonic fingerprint sensor chip.

[0079] Optionally, the silicon substrate 11 also includes power traces and ground traces, and the shielding metal disposed below the isolation layer 51 is connected to the power traces or electrically connected to the ground traces.

[0080] Based on the embodiments shown in Figures 3A to 3C above, this application also provides an ultrasonic fingerprint sensor chip. In this embodiment, an isolation layer is provided at the edge of the first end of the piezoelectric layer.

[0081] Figure 4A is a top view of an ultrasonic fingerprint sensor chip provided in an embodiment of this application; Figure 4B is an enlarged schematic diagram of the first end of the upper electrode and the first end of the piezoelectric layer in Figure 4A; and Figure 4C is a cross-sectional view along the AA' direction in Figure 4A. As shown in Figures 4A to 4C, the ultrasonic fingerprint sensor chip provided in this embodiment includes:

[0082] A silicon substrate 11, a lower electrode 14, a piezoelectric layer 12, an upper electrode 13, an isolation layer 51, and an upper electrode drive signal trace 15 disposed on the silicon substrate 11.

[0083] The piezoelectric layer 12 is located between the lower electrode 14 and the upper electrode 13. The edge of the upper electrode 13 near the first end of the upper electrode drive signal line 15 extends beyond the edge of the first end 121 of the piezoelectric layer to form an overhang region 23. The isolation layer 51 is located between the first end 121 of the piezoelectric layer and the upper electrode drive signal line 15 and is located below the upper electrode 13. The isolation layer 51 at least covers the overhang region 23.

[0084] An interconnecting contact 18 is also provided on the edge of the first end 131 of the upper electrode, and the interconnecting contact 18 is electrically connected to the upper electrode drive signal line 15.

[0085] The upper electrode drive signal trace 15 is used to transmit the drive signal of the upper electrode 13. The drive signal is used to control the piezoelectric layer 12 to emit ultrasonic signals.

[0086] The side face of the first end of the isolation layer 51 is attached to the side face of the first end 121 of the piezoelectric layer.

[0087] The ultrasonic fingerprint sensor chip provided in this embodiment, as shown in Figure 4C, has a piezoelectric layer 12 located between the upper electrode 13 and the lower electrode 14. For ease of explanation, the end of the upper electrode 13 closest to the upper electrode drive signal line 15 is referred to as the first end 131 of the upper electrode, and the end of the piezoelectric layer 12 closest to the upper electrode drive signal line 15 is referred to as the first end 121 of the piezoelectric layer. The isolation layer 51 is located between the first end 121 of the piezoelectric layer and the upper electrode drive signal line 15 and is located below the upper electrode 13. Furthermore, the side surface of the first end of the isolation layer 51 is bonded and connected to the side surface of the first end 121 of the piezoelectric layer, that is, the side surface of the first end of the isolation layer 51 is adjacent to and close to the side surface of the first end 121 of the piezoelectric layer.

[0088] As shown in Figure 4B, the edge of the first end 131 of the upper electrode extends beyond the edge of the first end 121 of the piezoelectric layer, forming an overhang region 23 in the upper electrode 13. After the upper electrode 13 completely crosses the piezoelectric layer 12, the overhang region 23 and the interconnecting contact 18 on the upper electrode 13 cover the insulating layer 51. The junction edge of the first end 131 of the upper electrode and the first end 121 of the piezoelectric layer is the edge of the first end 121 of the piezoelectric layer. The junction edge is flat and uniform. Although the overhang region 23 and the interconnecting contact 18 on the upper electrode 13 cover the insulating layer 51, since the piezoelectric properties of the insulating layer 51 are weak or non-existent, it will not excite ultrasonic signals, or in other words, the weak ultrasonic signals excited will not affect the ultrasonic signals generated by the piezoelectric layer 12.

[0089] As can be seen, the ultrasonic fingerprint sensor chip provided in this embodiment includes a silicon substrate and a lower electrode, a piezoelectric layer, an upper electrode, an isolation layer, and an upper electrode drive signal trace disposed on the silicon substrate. The piezoelectric layer is located between the lower electrode and the upper electrode. A protruding interconnecting contact is provided on the edge of the first end of the upper electrode, and the interconnecting contact is electrically connected to the upper electrode drive signal trace. The edge of the first end of the upper electrode extends beyond the edge of the first end of the piezoelectric layer, forming an overhang region. By attaching an isolation layer to the edge of the first end of the piezoelectric layer, the upper electrode completely crosses the piezoelectric layer and covers the isolation layer. The junction edge between the upper electrode and the piezoelectric layer is flat and uniform, allowing the piezoelectric layer to generate a uniform ultrasonic signal. Although the overhang region and interconnecting contact on the upper electrode cover the isolation layer and are electrically connected to the upper electrode drive signal trace, the isolation layer does not have piezoelectric properties and therefore does not generate an ultrasonic signal, avoiding fluctuations in the emitted ultrasonic signal and improving the stability and quality of the ultrasonic signal emitted by the ultrasonic fingerprint sensor chip.

[0090] Optionally, the distance between the side face of the first end of the isolation layer 51 and the side face of the first end 121 of the piezoelectric layer is less than or equal to 2 μm.

[0091] It is understood that the side face of the first end of the isolation layer 51 is attached to the side face of the first end 121 of the piezoelectric layer, and theoretically there should be no gap between the side faces. However, in the actual manufacturing process, due to factors such as manufacturing process and equipment, there may be gaps and distances between the side face of the first end of the isolation layer 51 and the side face of the first end 121 of the piezoelectric layer. These gaps need to be controlled within a certain error range, and the smaller the better. In this embodiment, the distance between the side face of the first end of the isolation layer 51 and the side face of the first end 121 of the piezoelectric layer is set to be less than or equal to 2 μm, thereby ensuring the piezoelectric isolation effect of the isolation layer 51 between the piezoelectric layer 12 and the upper electrode 13, and ensuring the uniformity, stability and quality of the ultrasonic signal emitted by the piezoelectric layer 12.

[0092] Optionally, the isolation layer 51 is made of plastic. Plastic materials do not have piezoelectric properties. By attaching an isolation layer 51 made of plastic material to the edge of the first end 121 of the piezoelectric layer, the isolation layer 51 will not generate ultrasonic signals and thus will not cause fluctuations in the ultrasonic signals emitted by the ultrasonic fingerprint sensor chip.

[0093] Optionally, the isolation layer 51 is a PI layer formed of PI material. PI material does not have piezoelectric properties. Therefore, by attaching the PI layer to the edge of the first end 121 of the piezoelectric layer, the PI layer will not generate ultrasonic signals and thus will not cause fluctuations in the ultrasonic signals emitted by the ultrasonic fingerprint sensor chip.

[0094] Optionally, the ratio of the piezoelectric coefficient of the isolation layer 51 to that of the piezoelectric layer 12 is less than 1 / 5.

[0095] In this implementation, the piezoelectric coefficient of the isolation layer 51 is much smaller than that of the piezoelectric layer 12. Compared with the piezoelectric layer 12, the isolation layer 51 has very weak piezoelectric characteristics or can be considered to have no piezoelectric characteristics. Therefore, the isolation layer 51 will not generate ultrasonic signals and will not cause fluctuations in the ultrasonic signals emitted by the ultrasonic fingerprint sensor chip.

[0096] Optionally, the thickness of the isolation layer 51 is less than the thickness of the piezoelectric layer 12. Optionally, the thickness of the isolation layer 51 is less than 10 μm.

[0097] Optionally, the thickness of the insulating layer 51 is less than the sum of the thickness of the piezoelectric layer 12 and the first thickness of the upper electrode 13, where the first thickness is the thickness of the upper electrode 13 at locations other than those exceeding region 23 and interconnecting contact 18. Optionally, the first thickness is between 10 μm and 40 μm.

[0098] Optionally, as shown in Figure 4C, the ultrasonic fingerprint sensor chip also includes a passivation layer 16. The passivation layer 16 is located below the interconnecting contact 18 on the upper electrode 13. A window is formed in the passivation layer 16 at the position corresponding to the interconnecting contact 18, forming a passivation layer window 161. The interconnecting contact 18 passes through the passivation layer window 161 and is electrically connected to the driving signal of the upper electrode 13.

[0099] Optionally, as shown in Figure 4D, the passivation layer 16 in the ultrasonic fingerprint sensor chip is also located below the first end 121 of the piezoelectric layer and the isolation layer 51.

[0100] In this implementation, compared to the ultrasonic fingerprint sensor chip shown in Figures 2A to 2C, an isolation layer 51 is attached to the passivation layer 16 on top of the passivation layer 16 and at the edge of the first end 121 of the piezoelectric layer. Since the isolation layer 51 does not have piezoelectric properties, the upper electrode 13 covers the isolation layer 51 after passing over the piezoelectric layer 12. This ensures the piezoelectric isolation effect of the isolation layer 51 between the piezoelectric layer 12 and the upper electrode 13, and ensures the uniformity, stability and quality of the ultrasonic signal emitted by the piezoelectric layer 12.

[0101] Optionally, as shown in Figure 4D, a shielding metal layer 42 is also provided below the isolation layer 51. This ensures the normal operation of the functional circuits below the isolation layer 51 in the ultrasonic fingerprint sensor chip, thereby ensuring the normal operation of the ultrasonic fingerprint sensor chip.

[0102] Optionally, as shown in Figure 4D, the ultrasonic fingerprint sensor chip further includes a passivation layer 16, which is located below the first end 121 of the piezoelectric layer and the upper electrode 13. A shielding metal layer 42 is located below the passivation layer 16, or the shielding metal layer 42 is embedded at the bottom of the passivation layer 16. By providing the shielding metal layer 42, the normal operation of the functional circuits below the isolation layer 51 in the ultrasonic fingerprint sensor chip is ensured, thereby ensuring the normal operation of the ultrasonic fingerprint sensor chip.

[0103] Optionally, the edge of the first end 121 of the piezoelectric layer is located between the two ends of the shielding metal layer 42.

[0104] It should be noted that the ultrasonic fingerprint sensor chip may also include other structures. This application does not limit the other structures included in the ultrasonic fingerprint sensor chip or the materials used in each structure.

[0105] Optionally, the ultrasonic fingerprint sensor chip may also include a shielding metal layer 41, a protective layer 19, and a PAD 17, as described above, and will not be repeated here.

[0106] Based on the embodiments shown in Figures 3A to 3C above, this application also provides an ultrasonic fingerprint sensor chip. In this embodiment, the ultrasonic fingerprint sensor chip includes a passivation layer, and the isolation layer is the passivation layer.

[0107] Figure 5A is a top view of an ultrasonic fingerprint sensor chip provided in an embodiment of this application; Figure 5B is an enlarged schematic diagram of the first end of the upper electrode and the first end of the piezoelectric layer in Figure 5A; and Figure 5C is a cross-sectional view along the AA' direction in Figure 5A. As shown in Figures 5A to 5C, the ultrasonic fingerprint sensor chip provided in this embodiment includes:

[0108] A silicon substrate 11, a lower electrode 14, a piezoelectric layer 12, an upper electrode 13, an isolation layer 51, and an upper electrode drive signal trace 15 disposed on the silicon substrate 11.

[0109] The piezoelectric layer 12 is located between the lower electrode 14 and the upper electrode 13. The edge of the upper electrode 13 near the first end of the upper electrode drive signal line 15 extends beyond the edge of the first end 121 of the piezoelectric layer to form an overhang region 23. The isolation layer 51 is located between the first end 121 of the piezoelectric layer and the upper electrode drive signal line 15 and is located below the upper electrode 13. The isolation layer 51 at least covers the overhang region 23.

[0110] An interconnecting contact 18 is also provided on the edge of the first end 131 of the upper electrode, and the interconnecting contact 18 is electrically connected to the upper electrode drive signal line 15.

[0111] The upper electrode drive signal trace 15 is used to transmit the drive signal of the upper electrode 13. The drive signal is used to control the piezoelectric layer 12 to emit ultrasonic signals.

[0112] The isolation layer 51 is a passivation layer 16 disposed on the silicon substrate 11, and the passivation layer 16 is located below the first end 121 of the piezoelectric layer and the upper electrode 13.

[0113] The ultrasonic fingerprint sensor chip provided in this embodiment, as shown in Figure 5C, has a piezoelectric layer 12 located between the upper electrode 13 and the lower electrode 14. For ease of explanation, the end of the upper electrode 13 closest to the upper electrode drive signal line 15 is referred to as the first end 131 of the upper electrode, and the end of the piezoelectric layer 12 closest to the upper electrode drive signal line 15 is referred to as the first end 121 of the piezoelectric layer. The ultrasonic fingerprint sensor chip also includes a passivation layer 16, which is located below the first end 121 of the piezoelectric layer and the upper electrode 13. An isolation layer 51 is located between the first end 121 of the piezoelectric layer and the upper electrode drive signal line 15, and is located below the upper electrode 13. Specifically, the isolation layer 51 is the passivation layer 16; or it can be understood as: the isolation layer 51 is a part of the passivation layer 16, specifically the portion of the isolation layer 51 located below the first end 121 of the piezoelectric layer and the first end 131 of the upper electrode.

[0114] As shown in Figure 5B, the edge of the first end 131 of the upper electrode extends beyond the edge of the first end 121 of the piezoelectric layer, forming an overhang region 23 in the upper electrode 13. After the upper electrode 13 completely crosses the piezoelectric layer 12, the overhang region 23 and the interconnecting contact 18 on the upper electrode 13 cover the isolation layer 51 / passivation layer 16. The junction edge of the first end 131 of the upper electrode and the first end 121 of the piezoelectric layer is the edge of the first end 121 of the piezoelectric layer. The junction edge is flat and uniform. Although the overhang region 23 and the interconnecting contact 18 on the upper electrode 13 cover the isolation layer 51 / passivation layer 16, since the piezoelectric characteristics of the isolation layer 51 / passivation layer 16 are weak or non-existent, it will not excite ultrasonic signals, or in other words, the weak ultrasonic signals excited will not affect the ultrasonic signals generated by the piezoelectric layer 12.

[0115] Compared to the ultrasonic fingerprint sensor chips shown in Figures 2A-2C, this embodiment shares the following structural similarities: both ultrasonic fingerprint sensor chips include a passivation layer 16, which is located below the first end 121 of the piezoelectric layer and the upper electrode 13. The structural difference lies in the fact that, in Figures 2A-2C, the edge of the first end 131 of the upper electrode is located within the edge of the first end 121 of the piezoelectric layer. Therefore, the interconnecting contact 18 provided at the first end 131 of the upper electrode needs to first cross the piezoelectric layer 12 before covering the passivation layer 16, resulting in an abrupt change at the junction edge of the first end 131 of the upper electrode and the first end 121 of the piezoelectric layer. In this embodiment, the edge of the first end 131 of the upper electrode extends beyond the edge of the first end 121 of the piezoelectric layer to form an overhang region 23. Therefore, the first end 131 of the upper electrode first crosses the piezoelectric layer 12 as a whole. The interconnecting contact 18 and the overhang region 23 provided on the first end 131 of the upper electrode directly cover the passivation layer 16, but do not directly cover the piezoelectric layer 12. Therefore, the junction edge between the first end 131 of the upper electrode and the first end 121 of the piezoelectric layer is flat and uniform.

[0116] As can be seen, the ultrasonic fingerprint sensor chip provided in this embodiment includes a silicon substrate and a lower electrode, a piezoelectric layer, an upper electrode, an isolation layer, and an upper electrode drive signal trace disposed on the silicon substrate, as well as a passivation layer. The isolation layer is the passivation layer. The piezoelectric layer is located between the lower electrode and the upper electrode. A protruding interconnect contact is provided on the edge of the first end of the upper electrode, and the interconnect contact is electrically connected to the upper electrode drive signal trace. The edge of the first end of the upper electrode extends beyond the edge of the first end of the piezoelectric layer, forming an overhang region. The upper electrode completely crosses the piezoelectric layer and covers the isolation layer / passivation layer. The junction edge between the upper electrode and the piezoelectric layer is flat and uniform, so that the piezoelectric layer generates a uniform ultrasonic signal. Although the overhang region and interconnect contact on the upper electrode cover the isolation layer / passivation layer and are electrically connected to the upper electrode drive signal trace, the isolation layer / passivation layer does not have piezoelectric properties, so it will not generate an ultrasonic signal, avoiding fluctuations in the emitted ultrasonic signal and improving the stability and quality of the ultrasonic signal emitted by the ultrasonic fingerprint sensor chip.

[0117] Optionally, as shown in Figure 5C, the first end 121 of the passivation layer 16, near the piezoelectric layer, extends into the bottom of the first end 121 of the piezoelectric layer.

[0118] Optionally, as shown in Figure 5C, a shielding metal layer 42 is also provided below the isolation layer 51 / passivation layer 16. The shielding metal layer 42 forms a shielding protection for the functional circuits in the ultrasonic fingerprint sensor chip below the isolation layer 51 / passivation layer 16, ensuring the normal operation of the functional circuits, and thus ensuring the normal operation of the ultrasonic fingerprint sensor chip.

[0119] Optionally, the shielding metal layer 42 is embedded at the bottom of the isolation layer 51 / passivation layer 16.

[0120] Optionally, the edge of the first end 121 of the piezoelectric layer is located between the two ends of the shielding metal layer 42.

[0121] Optionally, the thickness of the isolation layer 51 / passivation layer 16 is greater than 1.5 μm.

[0122] In this embodiment, the edge of the first end 131 of the upper electrode extends beyond the edge of the first end 121 of the piezoelectric layer, forming an overhang region 23. The upper electrode 13 completely spans the piezoelectric layer 12 and covers the isolation layer 51 / passivation layer 16. Since the driving voltage of the upper electrode 13 during operation is a high-frequency high voltage, it may damage the functional circuits in the ultrasonic fingerprint sensor chip. Therefore, by setting the thickness of the isolation layer 51 / passivation layer 16 to be greater than 1.5 μm, the isolation layer 51 / passivation layer 16 has a certain thickness, thereby ensuring the normal operation of the functional circuits in the ultrasonic fingerprint sensor chip. Moreover, if a shielding metal layer 42 is provided below the isolation layer 51 / passivation layer 16, electrical breakdown between the upper electrode 13 and the shielding metal layer 42 can also be avoided, further ensuring the normal operation of the functional circuits in the ultrasonic fingerprint sensor chip.

[0123] It should be noted that the ultrasonic fingerprint sensor chip may also include other structures. This application does not limit the other structures included in the ultrasonic fingerprint sensor chip or the materials used in each structure.

[0124] Optionally, the ultrasonic fingerprint sensor chip may also include a shielding metal layer 41, a protective layer 17, and a PAD 17, as described above, and will not be repeated here.

[0125] This application also provides an electronic device. For example, FIG6 is a structural diagram of an electronic device provided in an embodiment of this application. As shown in FIG6, the electronic device provided in this embodiment includes the ultrasonic fingerprint sensor chip 200 provided in the above embodiments of this application.

[0126] The electronic devices in this application include, but are not limited to:

[0127] (1) Mobile communication devices: These devices are characterized by their mobile communication capabilities and primarily aim to provide voice and data communication. These terminals include smartphones, multimedia phones, feature phones, and low-end phones.

[0128] (2) Ultra-mobile personal computer devices: These devices fall under the category of personal computers, possessing computing and processing capabilities, and generally also have mobile internet access features. These terminals include PDAs, MIDs, and UMPCs, such as the iPad.

[0129] (3) Portable entertainment devices: These devices can display and play multimedia content. This category includes: audio and video players (such as iPods), handheld game consoles, e-books, as well as smart toys and portable car navigation devices.

[0130] (4) Other electronic devices with data interaction functions.

[0131] Specific embodiments of the subject matter have now been described. Other embodiments are within the scope of the appended claims. In some cases, the actions described in the claims can be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing can be advantageous.

[0132] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0133] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more flowchart illustrations and / or one or more block diagrams.

[0134] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0135] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. An ultrasonic fingerprint sensor chip, comprising: A silicon substrate, and a lower electrode, a piezoelectric layer, an upper electrode, an isolation layer, and an upper electrode drive signal trace disposed on the silicon substrate; The piezoelectric layer is located between the lower electrode and the upper electrode. The edge of the upper electrode near the first end of the upper electrode drive signal trace extends beyond the edge of the first end of the piezoelectric layer to form an extended region. The isolation layer is located between the first end of the piezoelectric layer and the upper electrode drive signal trace and is located below the upper electrode. The isolation layer at least covers the extended region. An interconnecting contact is also provided on the edge of the first end of the upper electrode, and the interconnecting contact is electrically connected to the upper electrode drive signal trace. The upper electrode drive signal trace is used to transmit the drive signal of the upper electrode, and the drive signal is used to control the piezoelectric layer to emit ultrasonic signals.

2. The ultrasonic fingerprint sensor chip according to claim 1, wherein, The side face of the first end of the isolation layer is attached to the side face of the first end of the piezoelectric layer.

3. The ultrasonic fingerprint sensor chip according to claim 1 or 2, wherein, The distance between the side face of the first end of the isolation layer and the side face of the first end of the piezoelectric layer is less than or equal to 2 μm.

4. The ultrasonic fingerprint sensor chip according to claim 2, wherein, The isolation layer is made of plastic.

5. The ultrasonic fingerprint sensor chip according to claim 4, wherein, The isolation layer is a PI layer formed of polyimide (PI) material.

6. The ultrasonic fingerprint sensor chip according to any one of claims 2-5, wherein, The thickness of the insulating layer is less than the sum of the thickness of the piezoelectric layer and the first thickness of the upper electrode, where the first thickness is the thickness of the upper electrode at locations other than the overhanging area and the interconnecting contact.

7. The ultrasonic fingerprint sensor chip according to claim 6, wherein, The first thickness is between 10 μm and 40 μm.

8. The ultrasonic fingerprint sensor chip according to any one of claims 2-7, wherein, A passivation layer is also disposed on the silicon substrate, and the passivation layer is located at the first end of the piezoelectric layer and below the isolation layer.

9. The ultrasonic fingerprint sensor chip according to claim 1, wherein, The isolation layer is a passivation layer disposed on the silicon substrate, and the passivation layer is located at the first end of the piezoelectric layer and below the upper electrode.

10. The ultrasonic fingerprint sensor chip according to claim 9, wherein, The passivation layer is disposed on the bottom of the first end of the piezoelectric layer, near the first end of the piezoelectric layer.

11. The ultrasonic fingerprint sensor chip according to claim 9 or 10, wherein, The passivation layer has a thickness greater than 1.5 μm.

12. The ultrasonic fingerprint sensor chip according to any one of claims 1-11, wherein, The thickness of the insulating layer is less than the thickness of the piezoelectric layer.

13. The ultrasonic fingerprint sensor chip according to any one of claims 1-12, wherein, The thickness of the isolation layer is less than 10 μm.

14. The ultrasonic fingerprint sensor chip according to any one of claims 1-13, wherein, A shielding metal layer is also disposed on the silicon substrate, and the shielding metal layer is located below the isolation layer.

15. The ultrasonic fingerprint sensor chip according to claim 14, wherein, The edge of the first end of the piezoelectric layer is located between the two ends of the shielding metal layer.

16. The ultrasonic fingerprint sensor chip according to claim 14, wherein, A passivation layer is also disposed on the silicon substrate, and the passivation layer is located at the first end of the piezoelectric layer and below the upper electrode; The shielding metal layer is located below the passivation layer, or the shielding metal layer is embedded at the bottom of the passivation layer.

17. The ultrasonic fingerprint sensor chip according to claim 14, wherein, The silicon substrate also includes power traces and ground traces, and the shielding metal layer is connected to the power traces or electrically connected to the ground traces.

18. The ultrasonic fingerprint sensor chip according to any one of claims 8-11, 16, wherein, A passivation layer window is formed at the position corresponding to the interconnection contact in the passivation layer, and the interconnection contact passes through the passivation layer window to be electrically connected to the upper electrode drive signal.

19. The ultrasonic fingerprint sensor chip according to any one of claims 1-18, wherein, The silicon substrate is also provided with pads, which are electrically connected to the upper electrode drive signal traces.

20. The ultrasonic fingerprint sensor chip according to any one of claims 1-19, wherein, The upper electrode is a silver paste electrode.

21. The ultrasonic fingerprint sensor chip according to any one of claims 1-20, wherein, The ratio of the piezoelectric coefficient of the isolation layer to the piezoelectric coefficient of the piezoelectric layer is less than 1 / 5.

22. An electronic device, comprising: The ultrasonic fingerprint sensor chip as described in any one of claims 1-21.

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