Ultrasonic fingerprint chip packaging method and ultrasonic fingerprint chip

Abstract

The embodiment of the present application provides an ultrasonic fingerprint chip packaging method and an ultrasonic fingerprint chip, which relate to the field of semiconductor manufacturing technology. The ultrasonic fingerprint chip packaging method includes: providing a wafer, the surface of the wafer has an ultrasonic transmitter and an ultrasonic receiver, and a polarization layer is laid on the ultrasonic transmitter and the ultrasonic receiver; a seed layer is made on the polarization layer, and then a dielectric uniform electroplating layer is made by using the adhesion characteristics of the seed layer, the electroplating layer has good sound propagation performance, reduces the scattering of sound waves, effectively solves the problems of sound propagation loss and echo instability of traditional ultrasonic chips, and improves the acquisition, sensitivity, recognition accuracy and recognition rate of fingerprint signals.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to an ultrasonic fingerprint chip packaging method and an ultrasonic fingerprint chip. Background Art

[0002] Ultrasonic fingerprint chips use the reflection characteristics of ultrasound to obtain fingerprint information by detecting the reflected waves of fingerprint ridges and valleys. This technology has the advantages of non-contact, high precision, and strong anti-interference ability, and is widely used in identity recognition, security monitoring and other fields.

[0003] Since ultrasonic waves are affected by various factors during propagation, such as medium inhomogeneity and scattering, the sound propagation loss is large, which affects the signal acquisition and recognition accuracy. Secondly, during the propagation of ultrasonic waves, the echo may be unstable, which will also affect the signal acquisition and recognition accuracy.

[0004] How to improve the problems of sound propagation loss and echo instability in traditional ultrasonic chips is the technical problem to be solved by this application. Summary of the invention

[0005] The purpose of the present application is to provide an ultrasonic fingerprint chip packaging method and an ultrasonic fingerprint chip to improve the sound propagation loss and echo instability of traditional ultrasonic chips.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions.

[0007] In a first aspect, an embodiment of the present application provides an ultrasonic fingerprint chip packaging method, comprising:

[0008] A wafer is provided, wherein an ultrasonic wave transmitting part and an ultrasonic wave receiving part are provided on the surface of the wafer, and a polarization layer is provided on the ultrasonic wave transmitting part and the ultrasonic wave receiving part, wherein the material of the polarization layer is a piezoelectric material, and the polarization layer is used to convert an electrical signal into an ultrasonic wave and receive the reflected ultrasonic wave and convert it back into an electrical signal;

[0009] Making a seed layer on the polarization layer, the seed layer is used for conducting electricity and is prepared for a subsequent electroplating process, and the seed layer at least covers the ultrasonic emitting part area and the ultrasonic receiving part area;

[0010] An electroplating layer is formed on the seed layer.

[0011] Optionally, the step of forming an electroplating layer on the seed layer includes:

[0012] Forming a patterned film on the seed layer by photolithography, wherein the film at least exposes the ultrasonic emitting portion region and the ultrasonic receiving portion region;

[0013] Using an electroplating process, forming an electroplating layer on the film uncovered portion of the seed layer;

[0014] The film is removed, and then the portion of the seed layer not covered by the electroplating layer is removed.

[0015] Optionally, there is a pad on the surface of the wafer, and the polarization layer at least exposes the pad area and at least covers the ultrasonic transmitting part and the ultrasonic receiving part;

[0016] The step of making a seed layer on the polarization layer comprises:

[0017] Making a seed layer on the polarization layer and the pad to prepare for forming an electroplating layer on the pad;

[0018] After the patterned film is formed, the film at least exposes the ultrasonic wave transmitting portion region, the ultrasonic wave receiving portion region and the pad region.

[0019] Optionally, after removing the film, the ultrasonic fingerprint chip packaging method further includes:

[0020] A protection layer is manufactured, wherein the protection layer at least exposes the pad area.

[0021] Optionally, the protective layer at least covers the electroplating layer.

[0022] Optionally, the ultrasonic fingerprint chip packaging method further includes:

[0023] The single chip is separated by cutting in the cutting area through laser, hidden cutting or cutting wheel cutting.

[0024] Optionally, before completing the separation of the single chip, the ultrasonic fingerprint chip packaging method further includes:

[0025] The wafer is thinned by grinding.

[0026] Optionally, the material of the seed layer is metal such as TiCu.

[0027] In a second aspect, an embodiment of the present application provides an ultrasonic fingerprint chip, including a chip substrate, a seed layer and an electroplating layer;

[0028] The surface of the chip substrate is provided with a pad, an ultrasonic transmitting part and an ultrasonic receiving part, a polarization layer is laid on the ultrasonic transmitting part and the ultrasonic receiving part, the polarization layer at least exposes the pad area and at least covers the ultrasonic transmitting part and the ultrasonic receiving part, the material of the polarization layer is a piezoelectric material, and the polarization layer is used to convert an electrical signal into an ultrasonic wave and receive the reflected ultrasonic wave and convert it back into an electrical signal;

[0029] The seed layer is arranged on the polarization layer, the seed layer is used for conducting electricity and is prepared for the subsequent electroplating process, and the seed layer at least covers the ultrasonic emitting part area and the ultrasonic receiving part area;

[0030] The electroplating layer is arranged on the seed layer, and the electroplating layer at least covers the ultrasonic emitting part area and the ultrasonic receiving part area.

[0031] Optionally, the seed layer also covers the pad; the electroplating layer also covers the pad area.

[0032] Compared with the prior art, this application has the following beneficial effects:

[0033] The ultrasonic fingerprint chip packaging method provided in the embodiment of the present application utilizes the conductive characteristics of the seed layer for electroplating, and the electrochemical reaction causes metal ions to deposit on the surface of the seed layer. This has better binding force and can produce a uniform electroplating layer with good sound propagation performance, which reduces the scattering of sound waves, effectively solves the problems of sound propagation loss and unstable echo of traditional ultrasonic chips, and improves the acquisition, sensitivity, recognition accuracy and recognition rate of fingerprint signals. The process is simple, the production efficiency is high and the cost is controllable, which is conducive to improving the yield, facilitating large-scale production and application, and further meeting the market demand for high-precision and high-reliability ultrasonic sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic diagram of a wafer provided in an embodiment of the present application;

[0036] Figure 2 A schematic diagram of manufacturing a seed layer on a polarization layer provided in an embodiment of the present application;

[0037] Figure 3 A schematic diagram of making an electroplating layer on a seed layer provided in an embodiment of the present application;

[0038] Figure 4 A schematic diagram of forming a patterned film provided in an embodiment of the present application;

[0039] Figure 5 A schematic diagram of manufacturing an electroplating layer provided in an embodiment of the present application;

[0040] Figure 6 A schematic diagram of a film removal method provided in an embodiment of the present application;

[0041] Figure 7 A schematic diagram of a wafer with a pad and a polarization layer provided in an embodiment of the present application;

[0042] Figure 8 A schematic diagram of a wafer with a pad provided in an embodiment of the present application;

[0043] Fig. 9 A schematic diagram of a seed layer covering a pad provided in an embodiment of the present application;

[0044] Fig.10 A schematic diagram of a film-covered pad provided in an embodiment of the present application;

[0045] Fig.11 A schematic diagram of an electroplating layer not covering a pad provided in an embodiment of the present application;

[0046] Fig.12 A schematic diagram showing a solder pad exposed after a film provided in an embodiment of the present application is removed;

[0047] Fig.13 A schematic diagram of a film not covering a pad provided in an embodiment of the present application;

[0048] Fig.14 For Fig.13 Schematic diagram of electroplating on the foundation;

[0049] Fig.15 A schematic diagram of a pad covered with an electroplating layer provided in an embodiment of the present application;

[0050] Fig.16 A schematic diagram of manufacturing a protective layer provided in an embodiment of the present application;

[0051] Fig.17 For the general Fig.16 Schematic diagram of wafer thinning shown;

[0052] Fig.18 A schematic diagram of manufacturing multiple chips from a wafer provided in an embodiment of the present application;

[0053] Fig.19 A schematic diagram of an ultrasonic fingerprint chip provided in an embodiment of the present application;

[0054] Fig. 20 A schematic diagram of an ultrasonic fingerprint chip with a pad covered by an electroplating layer provided in an embodiment of the present application;

[0055] Fig.21A schematic diagram of an ultrasonic fingerprint chip with a protective layer provided in an embodiment of the present application.

[0056] Description of reference numerals:

[0057] 101 Wafer

[0058] 102 Ultrasonic emission unit

[0059] 103 Ultrasonic receiving unit

[0060] 104 pads

[0061] 106 Polarization layer

[0062] 107 seed layer

[0063] 108 Film

[0064] 109 electroplating layer

[0065] 110 protection layer

[0066] 113 Functional Areas DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described in the drawings here can be arranged and designed in various different configurations.

[0068] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0069] In the description of the present application, it should be noted that “connection” should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium.

[0070] The present application embodiment provides an ultrasonic fingerprint chip packaging method, comprising:

[0071] Step 1, such as Figure 1 , providing a wafer 101, Figure 1A part of a wafer 101 is shown. An ultrasonic transmitter 102 and an ultrasonic receiver 103 are provided on the surface of the wafer 101. A polarization layer 106 is provided on the ultrasonic transmitter 102 and the ultrasonic receiver 103. The polarization layer 106 may at least cover the ultrasonic transmitter 102 and the ultrasonic receiver 103. The polarization layer 106 is made of a piezoelectric material such as PVDF (polyvinylidene fluoride), which has the advantages of chemical resistance, low acoustic impedance, corrosion resistance, high mechanical strength, strong plasticity, etc. The polarization layer 106 is used to convert an electrical signal into an ultrasonic wave and receive the reflected ultrasonic wave and convert it back into an electrical signal.

[0072] Step 2, such as Figure 2 , a seed layer 107 is formed on the polarization layer 106. The seed layer 107 can be formed by processes such as sputtering and evaporation. The seed layer 107 is used for conducting electricity and is prepared for the subsequent electroplating process. The seed layer 107 at least covers the ultrasonic emitting part 102 area and the ultrasonic receiving part 103 area, so that the subsequent electroplating layer can cover the ultrasonic emitting part 102 area and the ultrasonic receiving part 103 area;

[0073] Step 3, such as Figure 3 The electroplating layer 109 is formed on the seed layer 107. The electroplating layer 109 can be formed by electroplating tin, silver, tin-silver, copper, etc. The electroplating layer 109 covers the ultrasonic emitting part 102 area and the ultrasonic receiving part 103 area.

[0074] The material of the seed layer can be metals such as TiCu. The ultrasonic fingerprint chip packaging method uses the conductive properties of the seed layer 107 for electroplating. The electrochemical reaction causes metal ions to deposit on the surface of the seed layer. The electroplating process has the advantages of uniform coating, strong bonding, and high temperature corrosion resistance. It also provides additional physical properties such as conductivity and wear resistance. Since the surface of the electroplated layer is very uniform and flat, the scattering of sound waves is reduced, which can improve the acoustic propagation loss and echo instability of the ultrasonic fingerprint chip, and improve the acquisition, sensitivity, recognition accuracy and recognition rate of fingerprint signals.

[0075] The diversity of different metal electroplating processes provides flexible options for different needs. According to the characteristics of different metals, the heat dissipation of the chip can be improved, the penetration of the ultrasonic chip can be enhanced, and the performance of the chip can be better exerted.

[0076] In addition, the ultrasonic fingerprint chip packaging method has a simple process, high production efficiency and controllable cost, which is conducive to large-scale production and application.

[0077] In the above step 3, the electroplating layer may be obtained by electroplating first and then the excess electroplating layer area may be removed by etching or the like.

[0078] In step 3, the electroplating layer can also be obtained by first performing photolithography coating, and then electroplating the seed layer exposed by the film, that is, step 3 includes:

[0079] Step 3.1, such as Figure 4 , forming a patterned film 108 on the seed layer 107 by photolithography, wherein the film 108 at least exposes the ultrasonic emitting portion 102 region and the ultrasonic receiving portion 103 region;

[0080] Step 3.2, such as Figure 5 , using an electroplating process to form an electroplated layer 109 on the uncovered portion of the film 108 of the seed layer 107;

[0081] Step 3.3, such as Figure 6 , remove the film 108; then remove the portion of the seed layer 107 not covered by the electroplating layer 109, and the same Figure 3 The portion of the seed layer 107 not covered by the electroplating layer 109 may be removed by wet etching.

[0082] As a part of the ultrasonic fingerprint chip, the pad is used to connect the functional part of the ultrasonic fingerprint chip with the external circuit, such as the external circuit flexible board, for power supply and output exchange of analysis results. The pad can be made after electroplating or before electroplating. The pad can be provided by the wafer itself. In the packaging method, the pad part can be protected by electroplating, or no processing action can be performed on the pad. In one embodiment, the wafer 101 used in step 1 is as follows: Figure 7 The wafer 101 has a pad 104 , and the pad 104 may be made before making the seed layer. The polarization layer 106 may at least expose the pad area and at least cover the ultrasonic emitting portion 102 and the ultrasonic receiving portion 103 .

[0083] The wafer in step 1 can be obtained in the following manner: first, a wafer having an ultrasonic emitting portion 102, an ultrasonic receiving portion 103 and a pad 104 on its surface is provided. Figure 8 , and then lay the polarization layer 106 on the wafer surface to obtain Figure 7 Wafer shown.

[0084] In step 2, a seed layer 107 is formed on the polarization layer 106. The seed layer 107 can cover the entire surface of the wafer. Fig. 9 , the seed layer 107 can cover the pad area. In one embodiment, the excess seed layer is removed in a subsequent step to expose the pad area. In another embodiment, the seed layer in the pad area is retained, and an electroplating layer is formed on the seed layer in the pad area, and the material of the electroplating layer covers the pad to play a conductive and connecting role.

[0085] In the above step 3.1, in order not to make an extra area of ​​electroplating layer on the extra area of ​​seed layer, as Fig.10 , a patterned film 108 may be formed on the seed layer by photolithography coating, and the film 108 may cover the pad area;

[0086] In the above step 3.2, if Fig.11 , using an electroplating process, forming an electroplating layer 109 on the uncovered portion of the film 108 of the seed layer 107, where the electroplating layer 109 does not cover the pad area;

[0087] In the above step 3.3, if Fig.12 , remove the film 108, and then remove the portion of the seed layer 107 that is not covered by the electroplating layer 109, and the pad 104 is directly exposed.

[0088] In another embodiment of the above step 3.1, the film 108 may expose the seed layer of the pad area, such as Fig.13 Then in step 3.2, the electroplating layer 109 is formed on the uncovered portion of the film 108 of the seed layer 107. At this time, the electroplating layer 109 covers the pad area, such as Fig.14 ; Further, in step 3.3, the film 108 is removed, and then the portion of the seed layer 107 not covered by the electroplating layer 109 is removed, and the pad 104 is still covered by the electroplating layer, such as Fig.15 Removing the excess seed layer can prevent the excess seed layer from affecting the ultrasonic echo effect.

[0089] The simultaneous electroplating of the pad area, that is, protecting the pad part, can better avoid the risk of oxidation at the pad position, improve the contact reliability between the pad and the external circuit flexible board, and improve the problems of poor adhesion and high contact resistance.

[0090] After removing the film 108 in step 3.3, the ultrasonic fingerprint chip packaging method may further include: Fig.16 , make a protective layer 110, the protective layer 110 at least exposes the pad 104 area, and the protective layer 110 at least covers the top of the electroplating layer 109. The protective layer 110 can also cover the sidewalls of the sidewall seed layer 107 of the electroplating layer 109, which can play a more stable protective role. The protective layer can be made by spraying, spin coating and other methods. The material of the protective layer can also be a variety of materials, not limited to materials such as photoresist or film. The protective layer can protect the electroplating layer from erosion by the external environment and extend the service life of the electroplating layer. Materials that are resistant to extreme temperatures, have excellent mechanical properties, have excellent dimensional stability, and have low shrinkage can be selected to improve chip reliability. In addition, the protective layer has high microwave permeability and has no effect on the performance of the ultrasonic chip.

[0091] Before the separation of the single chip is completed by cutting, the ultrasonic fingerprint chip packaging method may also include: thinning the wafer by grinding. Fig.17 The thinning process can meet the process requirements of different chip thicknesses, reduce chip stress, and improve the chip's heat dissipation performance.

[0092] like Fig.18 , a wafer can be used to make multiple chips, each chip has a pad 104 and a functional area 113. Finally, the single chip can be separated by cutting in the cutting area by laser, hidden cutting or cutting wheel cutting.

[0093] Based on the above embodiments, the embodiments of the present application further provide an ultrasonic fingerprint chip, which can be obtained by the above ultrasonic fingerprint chip packaging method.

[0094] like Fig.19 The ultrasonic fingerprint chip includes a chip substrate, and a pad 104, an ultrasonic transmitting part 102 and an ultrasonic receiving part 103 are provided on the surface of the chip substrate. A polarization layer 106 is laid on the ultrasonic transmitting part 102 and the ultrasonic receiving part 103. The polarization layer 106 at least exposes the pad 104 area and the cutting road area and at least covers the ultrasonic transmitting part 102 and the ultrasonic receiving part 103. The material of the polarization layer 106 is a piezoelectric material. The polarization layer 106 is used to convert electrical signals into ultrasonic waves and receive reflected ultrasonic waves and convert them back into electrical signals.

[0095] A seed layer 107 is disposed on the polarization layer 106 , and the seed layer 107 at least covers the ultrasonic wave transmitting portion 102 region and the ultrasonic wave receiving portion 103 region.

[0096] An electroplating layer 109 is disposed on the seed layer 107 , and the electroplating layer 109 at least covers the ultrasonic emitting portion 102 region and the ultrasonic receiving portion 103 region.

[0097] like Fig. 20 , the seed layer 107 of the ultrasonic fingerprint chip can also cover the pad 104; the electroplating layer 109 can also cover the pad 104 area.

[0098] like Fig.21 The ultrasonic fingerprint chip may further include a protective layer, and the protective layer 110 covers at least the top of the electroplating layer 109. The protective layer 110 may also cover the sidewalls of the electroplating layer 109 and the sidewalls of the seed layer 107, which may provide a more stable protection.

[0099] The above-described device and system embodiments are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. A person skilled in the art may understand and implement the present embodiment without creative effort.

[0100] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for packaging an ultrasonic fingerprint chip, characterized in that: include: A wafer (101) is provided, wherein an ultrasonic transmitting portion (102) and an ultrasonic receiving portion (103) are provided on a surface of the wafer (101), wherein the ultrasonic transmitting portion (102) and the ultrasonic receiving portion (103) are located at the same height, and a polarization layer (106) is provided on the ultrasonic transmitting portion (102) and the ultrasonic receiving portion (103), wherein the material of the polarization layer (106) is a piezoelectric material, and the polarization layer (106) is used to convert an electrical signal into an ultrasonic wave and to receive the reflected ultrasonic wave and convert it back into an electrical signal; A seed layer (107) is fabricated on the polarization layer (106), wherein the seed layer (107) is used for conducting electricity and is prepared for a subsequent electroplating process, and the seed layer (107) at least covers an area of ​​the ultrasonic emitting portion (102) and an area of ​​the ultrasonic receiving portion (103); An electroplating layer (109) is formed on the seed layer (107); the seed layer (107) is located between the electroplating layer and the polarization layer (106); the ultrasonic wave emitted by the ultrasonic emitting unit (102) needs to pass through the polarization layer (106), the seed layer (107) and the electroplating layer (109) when reaching the target object; and the ultrasonic wave reflected by the external target needs to pass through the electroplating layer (109), the seed layer (107) and the polarization layer (106) when reaching the ultrasonic receiving unit (103).

2. The ultrasonic fingerprint chip packaging method according to claim 1, characterized in that: The step of making an electroplating layer (109) on the seed layer (107) comprises: Forming a patterned film (108) on the seed layer (107) by photolithography, wherein the film (108) at least exposes the ultrasonic emitting portion (102) region and the ultrasonic receiving portion (103) region; Using an electroplating process, forming an electroplating layer (109) on the portion of the seed layer (107) not covered by the film (108); The film (108) is removed, and then the portion of the seed layer (107) not covered by the electroplating layer (109) is removed.

3. The ultrasonic fingerprint chip packaging method according to claim 2, characterized in that: The surface of the wafer (101) is provided with a solder pad (104), and the polarization layer (106) at least exposes the solder pad (104) area and at least covers the ultrasonic transmitting part (102) and the ultrasonic receiving part (103); The step of making a seed layer (107) on the polarization layer (106) comprises: Making a seed layer (107) on the polarization layer (106) and the pad (104) to prepare for forming an electroplating layer (109) on the pad (104); After the patterned film (108) is formed, the film (108) at least exposes the ultrasonic wave transmitting portion (102) region, the ultrasonic wave receiving portion (103) region and the pad (104) region.

4. The ultrasonic fingerprint chip packaging method according to claim 3, characterized in that: After removing the film (108), the ultrasonic fingerprint chip packaging method further comprises: A protective layer (110) is manufactured, wherein the protective layer (110) at least exposes the pad (104) area.

5. The ultrasonic fingerprint chip packaging method according to claim 4, characterized in that: The protective layer (110) at least covers the electroplating layer (109).

6. The ultrasonic fingerprint chip packaging method according to claim 1, characterized in that: The ultrasonic fingerprint chip packaging method also includes: The single chip is separated by cutting in the cutting area through laser, hidden cutting or cutting wheel cutting.

7. The ultrasonic fingerprint chip packaging method according to claim 6, characterized in that: Before completing the separation of the single chip, the ultrasonic fingerprint chip packaging method further includes: The wafer is thinned by grinding.

8. The ultrasonic fingerprint chip packaging method according to claim 1, characterized in that: The material of the seed layer is TiCu.

9. An ultrasonic fingerprint chip, characterized in that: It comprises a chip substrate, a seed layer (107) and an electroplating layer (109); The chip substrate surface has a solder pad (104), an ultrasonic transmitting part (102) and an ultrasonic receiving part (103); the ultrasonic transmitting part (102) and the ultrasonic receiving part (103) are located at the same height; a polarization layer (106) is laid on the ultrasonic transmitting part (102) and the ultrasonic receiving part (103); the polarization layer (106) at least exposes the solder pad (104) area and at least covers the ultrasonic transmitting part (102) and the ultrasonic receiving part (103); the material of the polarization layer (106) is a piezoelectric material; the polarization layer (106) is used to convert an electrical signal into an ultrasonic wave and to receive the reflected ultrasonic wave and convert it back into an electrical signal; The seed layer (107) is arranged on the polarization layer (106), the seed layer (107) is conductive and is prepared for a subsequent electroplating process, and the seed layer (107) at least covers an area of ​​the ultrasonic emitting part (102) and an area of ​​the ultrasonic receiving part (103); The electroplating layer (109) is arranged on the seed layer (107), and the electroplating layer (109) at least covers the ultrasonic emitting part (102) area and the ultrasonic receiving part (103) area; the seed layer (107) is located between the electroplating layer and the polarization layer (106); the ultrasonic wave emitted by the ultrasonic emitting part (102) needs to pass through the polarization layer (106), the seed layer (107) and the electroplating layer (109) when reaching the target object; the ultrasonic wave reflected by the external target needs to pass through the electroplating layer (109), the seed layer (107) and the polarization layer (106) when reaching the ultrasonic receiving part (103).

10. The ultrasonic fingerprint chip according to claim 9, characterized in that: The seed layer (107) also covers the pad (104); The electroplating layer (109) also covers the pad (104) area.

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