CN112257602B

CN112257602B - Ultrasonic sensor, fingerprint identification module and electronic equipment

Info

Publication number: CN112257602B
Application number: CN202011142527.XA
Authority: CN
Inventors: 陆斌; 王红超; 沈健
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Huike Singapore Holdings Private Ltd
Priority date: 2020-06-12
Filing date: 2020-06-12
Publication date: 2024-04-26
Anticipated expiration: 2040-06-12
Also published as: CN111428702B; CN112257602A; CN111428702A

Abstract

Some embodiments of the application provide an ultrasonic sensor comprising: a chip including a first pixel electrode array including a plurality of first pixel electrodes; the rewiring expansion layer is arranged above the chip and comprises a second pixel electrode array, the second pixel electrode array comprises a plurality of second pixel electrodes, the second pixel electrodes are respectively connected with the first pixel electrodes, and the area of the second pixel electrode array is larger than that of the first pixel electrode array; and the sound-electricity conversion layer is arranged above the rewiring expansion layer and is used for converting ultrasonic signals and electric signals. An increase in the recognition area without increasing the chip area is realized.

Description

Ultrasonic sensor, fingerprint identification module and electronic equipment

Technical Field

The embodiment of the application relates to the technical field of electronic information, in particular to an ultrasonic sensor, a fingerprint identification module and electronic equipment.

Background

There is a strong demand for large area fingerprint recognition in the market at present, the size of the fingerprint recognition area is consistent with the size of the ultrasonic sensor, in order to increase the area of the fingerprint recognition area, the area of the ultrasonic sensor must be increased in the prior art, and the manufacturing cost of the ultrasonic sensor is proportional to the area, so that the cost is increased.

Disclosure of Invention

The application provides an ultrasonic sensor, a fingerprint identification module and electronic equipment, which can greatly increase the detection area of a fingerprint identification area on the basis of not increasing the cost.

In a first aspect, there is provided an ultrasonic sensor comprising: a chip including a first pixel electrode array including a plurality of first pixel electrodes; the rewiring expansion layer is arranged above the chip and comprises a second pixel electrode array, the second pixel electrode array comprises a plurality of second pixel electrodes, the second pixel electrodes are respectively connected with the first pixel electrodes, and the area of the second pixel electrode array is larger than that of the first pixel electrode array; and the sound-electricity conversion layer is arranged above the rewiring expansion layer and is used for converting ultrasonic signals and electric signals.

Compared with the prior art, the embodiment of the application has the advantages that the electrical signal is fanned out from the first pixel electrode array in the chip to the second pixel electrode array with a larger area by arranging the rewiring extension layer between the acoustic-electric conversion layer and the chip, so that the identification area is increased under the condition of not increasing the area of the chip.

In one possible implementation manner, the rewiring extension layer includes an insulating layer and a metal wire, the second pixel electrode array is disposed on an upper surface of the insulating layer, the metal wire is disposed in the insulating layer, and the plurality of second pixel electrodes are respectively connected with the plurality of first pixel electrodes through the metal wire.

In one possible implementation manner, the rewiring extension layer further includes a second pad, where the second pad is located on a lower surface of the insulating layer, and the second pad is used for connecting with the first pixel electrode and connecting with the second pixel electrode through the metal routing.

In a possible implementation manner according to the first aspect, a micro-welding spot is disposed on the first pixel electrode, and the micro-welding spot is used for connecting with the second pixel electrode.

In a possible implementation manner according to the first aspect, the second bonding pad is fixedly connected with the micro-pad.

In a possible implementation manner, according to the first aspect, a space between two adjacent second pixel electrodes is smaller than 100um.

In a possible implementation manner according to the first aspect, the acoustic-electric conversion layer includes a piezoelectric material layer and an electrode layer, and the piezoelectric material layer is fixedly connected with the second pixel electrode array.

In one possible implementation manner, the semiconductor device further includes a plastic package housing, the plastic package housing is located on the lower surface of the insulating layer, and the plastic package housing wraps the chip.

In one possible implementation manner, the device further comprises a conductive part arranged in the plastic package shell, wherein one end of the conductive part is connected with the rewiring expansion layer, and the other end of the conductive part is connected with a third bonding pad positioned below the plastic package shell.

In a possible implementation manner of the first aspect, the method further includes a copper pillar disposed above the rewiring extension layer and electrically connected to the rewiring extension layer, the copper pillar extending away from the chip direction for electrically connecting the ultrasonic sensor and the FPC, wherein the copper pillar is a conductive portion.

In a possible implementation form of the first aspect, the chip comprises a sensor chip.

In one possible implementation manner, the chip further comprises a control chip, and the sensor chip is spaced from the control chip by less than 100um.

In a possible implementation manner according to the first aspect, the sensor chip and the control chip communicate with each other through the metal wire.

In a second aspect, a fingerprint recognition module is provided, comprising the ultrasonic sensor of the first aspect or any optional implementation of the first aspect, and a flexible circuit board.

In a possible implementation manner of the second aspect, the ultrasonic sensor further includes a conductive portion disposed in the plastic package housing, one end of the conductive portion is electrically connected to the rewiring expansion layer, and the other end of the conductive portion is connected to a third bonding pad located under the plastic package housing.

In a possible implementation manner of the second aspect, the ultrasonic sensor further includes a copper pillar disposed above the rewiring extension layer and electrically connected to the rewiring extension layer, the copper pillar extending away from the chip for electrically connecting the ultrasonic sensor to the FPC, wherein the copper pillar is a conductive portion.

In a possible implementation manner according to the second aspect, the flexible circuit board is disposed below the ultrasonic sensor.

In a possible implementation manner according to the second aspect, the acoustic-electric conversion layer includes an electrode layer, the flexible circuit board is fixedly connected to the third pad, and the flexible circuit board is fixedly connected to the electrode layer through a conductive structure.

In a possible implementation manner according to the second aspect, the acousto-electric conversion layer includes an electrode layer, the flexible circuit board is fixedly connected with the third pad, and the electrode layer is connected with the second pixel electrode.

In a possible implementation manner according to the second aspect, the flexible circuit board is arranged between the ultrasonic sensor and the screen.

In a possible implementation manner according to the second aspect, the sound-electricity conversion layer includes an electrode layer, and the flexible circuit board is fixedly connected with one end of the copper pillar and the electrode layer, wherein the copper pillar is a conductive part.

In a third aspect, there is provided an electronic device comprising a screen and the fingerprint recognition module in the second aspect or any optional implementation manner of the second aspect, the screen being connected to the flexible circuit board through the adhesive layer.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, which are not to be construed as limiting the embodiments unless specifically indicated otherwise. The following embodiments are divided for convenience of description, and should not be construed as limiting the specific implementation of the present invention, and the embodiments can be mutually combined and referred to without contradiction.

FIG. 1 is a schematic diagram of a prior art ultrasonic sensor;

FIG. 2 is a schematic diagram of an ultrasonic fingerprint recognition module in the prior art;

FIG. 3 is a schematic view of an ultrasonic sensor according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a structural stack of the ultrasonic transducer of FIG. 3;

FIG. 5 is a schematic diagram of a process flow of manufacturing an ultrasonic sensor according to an embodiment of the present application;

FIG. 6 is a schematic diagram of a chip manufacturing process according to an embodiment of the application;

FIG. 7 is a schematic diagram of a chip according to an embodiment of the present application;

FIG. 8 is a schematic diagram of a manufacturing process of a rewiring extension layer according to an embodiment of the application;

FIG. 9 is a schematic diagram of a rewiring extension layer according to an embodiment of the present application;

FIG. 10 is a schematic flow chart of the interconnection of the chip and the rewiring extension layer in the embodiment of the application;

FIG. 11 is a schematic diagram of a chip and rewiring extension layer interconnect in an embodiment of the application;

FIG. 12 is a schematic diagram of a rewiring extension layer removal slide exposing a second pixel electrode array in accordance with an embodiment of the present application;

FIG. 13 is a schematic diagram of a process flow of fabricating an acousto-electric conversion layer according to an embodiment of the present application;

FIG. 14 is a schematic view of an ultrasonic sensor according to an embodiment of the present application;

FIG. 15 is a schematic view of a partial manufacturing process of an ultrasonic sensor according to another embodiment of the present application;

FIG. 16 is a schematic view showing a part of the structure of an ultrasonic sensor according to another embodiment of the present application;

FIG. 17 is a schematic view of a portion of a process flow of manufacturing an ultrasonic sensor according to another embodiment of the application;

FIG. 18 is a schematic view showing a part of the structure of an ultrasonic sensor according to another embodiment of the present application;

FIG. 19 is a schematic view of an ultrasonic fingerprint sensor according to another embodiment of the present application;

FIG. 20 is a schematic diagram of an ultrasonic fingerprint recognition module according to another embodiment of the present application;

FIG. 21 is a schematic view of an ultrasonic fingerprint recognition module attached under a screen or a cover plate according to another embodiment of the present application;

FIG. 22 is a schematic view of a portion of an ultrasonic sensor according to yet another embodiment of the present application;

fig. 23 is a schematic structural diagram of an ultrasonic sensor corresponding to step S1021 in another embodiment of the present application;

Fig. 24 is a schematic structural diagram of an ultrasonic sensor corresponding to step S1022 in another embodiment of the present application;

fig. 25 is a schematic structural diagram of an ultrasonic sensor corresponding to step S1023 in yet another embodiment of the present application;

FIG. 26 is a schematic view of an ultrasonic sensor with blind vias and an insulating layer according to a further embodiment of the present application;

FIG. 27 is a schematic view showing the structure of an ultrasonic sensor forming an adhesion layer and a seed layer according to still another embodiment of the present application;

FIG. 28 is a schematic view of an ultrasonic sensor with vertical conductive structures formed thereon according to yet another embodiment of the present application;

FIG. 29 is a schematic view of a plastic package housing formed after a vertical conductive structure is fabricated on an ultrasonic sensor according to another embodiment of the present application;

FIG. 30 is a schematic diagram illustrating a structure of an ultrasonic fingerprint recognition module according to another embodiment of the present application;

FIG. 31 is a schematic view showing a structure of a copper pillar fabricated on an ultrasonic sensor according to another embodiment of the present application;

Fig. 32 is a schematic structural diagram of the ultrasonic fingerprint recognition module corresponding to fig. 31;

FIG. 33 is a schematic view of the structure of the module of FIG. 32 under a screen or cover;

fig. 34 is a schematic view of a structure of two chips fabricated in an ultrasonic sensor according to another embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, some embodiments of the present application will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.

Fig. 1 is a structure of an ultrasonic sensor, and a structure of an ultrasonic sensor 100 includes a chip and an acoustic-electric conversion layer. The chip includes a substrate 101 and pixel circuits (not shown) disposed over the substrate 101; the pixel circuit is composed of a pixel electrode array 102, a thin-film-transistor (TFT), a capacitor, a resistor, and the like. The acoustic-electric conversion layer includes a piezoelectric material layer 103 and an electrode layer 104 disposed over the pixel electrode array 102, the electrode layer 104 being disposed over the piezoelectric material layer 103.

Fig. 2 is a schematic structural diagram of an ultrasonic fingerprint recognition module, where the ultrasonic fingerprint recognition module includes an ultrasonic sensor 100, a flexible circuit board (Flexible Printed Circuit, FPC) 202, and a control chip 201, where the control chip 201 is used to implement functions such as timing control and image processing. The ultrasonic sensor 100 and the control chip 201 realize communication with each other through the FPC 202. The size of the identification area of the ultrasonic fingerprint module is consistent with the size of the ultrasonic sensor 100, the identification area is too small to obtain enough characteristic points of the object to be detected, and therefore the identification function is greatly weakened. To increase the recognition area, the chip area must be increased, and the area of the chip and the cost are positively correlated, and the larger the chip area, the higher the cost.

To this end, the present application provides an ultrasonic sensor capable of increasing a recognition area without increasing a chip area.

Referring to fig. 3 and 4, an ultrasonic sensor 300 includes a chip, a rewiring extension layer, and an acoustic-to-electric conversion layer, the chip including a substrate 301 and a first pixel electrode array 302 disposed on the substrate, the first pixel electrode array 302 including a plurality of first pixel electrodes, the plurality of first pixel electrodes being arranged in an array; the rewiring extension layer is disposed above the chip, wherein the rewiring extension layer includes an insulating layer 306, a metal trace 307, and a second pixel electrode array 305, and the second pixel electrode array 305 includes a plurality of second pixel electrodes arranged in an array. The plurality of second pixel electrodes in the second pixel electrode array 305 are respectively connected with the plurality of first pixel electrodes in the first pixel electrode array 302, and the area of the second pixel electrode array 305 is larger than the area of the first pixel electrode array 302. The acoustic-electric conversion layer is disposed above the rewiring extension layer for performing conversion of the ultrasonic signal and the electric signal. The acoustoelectric conversion layer includes a piezoelectric material layer 303 and an electrode layer 304. The rewiring extension layer receives the electrical signal of the piezoelectric material layer 303 by resistive or capacitive coupling, wherein the electrical signal is generated as a result of the piezoelectric material layer 303 being excited by ultrasonic waves, and the electrical signal is conducted to the chip. The rewiring expansion layer is connected with the acoustic-electric conversion layer and is grounded through an electrode layer in the acoustic-electric conversion layer, and when the ultrasonic sensor emits ultrasonic waves, the rewiring expansion layer couples voltage to the piezoelectric material layer; when polarizing, the rewiring expansion layer applies a required electric field to the piezoelectric material layer, so that the piezoelectric material layer has piezoelectric properties.

According to the embodiment of the application, the rewiring expansion layer is arranged between the acoustic-electric conversion layer and the chip, so that the electric signals are fanned out from the first pixel electrode array in the chip to the second pixel electrode array with a larger area, and the identification area is increased under the condition of not increasing the area of the chip.

The manufacturing flow of the ultrasonic sensor according to the embodiment of the application is shown in fig. 5, and mainly includes:

S510, manufacturing a chip and a rewiring extension layer;

s520, interconnecting the chip and the rewiring expansion layer;

S530, disposing an acoustic-electric conversion layer on the rewiring extension layer.

Fig. 6 is a schematic flow chart of a method for fabricating a chip in an embodiment of the application, the method including some or all of the following steps.

In S610, a silicon wafer is selected as a substrate.

The substrate may also include a deposition layer, an oxide layer, a bonding layer, for example, the substrate may be a Silicon-On-Insulator (SOI) substrate

In S620, a sensor circuit and a control circuit are provided on the substrate.

The sensor circuit and the control circuit are provided using a complementary metal oxide semiconductor (Complementary Metal Oxide Semiconductor, CMOS) or a double diffused metal oxide semiconductor (BCD) process, and the sensor circuit and the control circuit may be provided on the same substrate or separately provided on different substrates to form the sensor chip and the control chip. For example, a sensor circuit may be fabricated on a glass substrate using a TFT process to form a sensor chip, and a control circuit may be fabricated on a silicon substrate using a CMOS process to form a control chip. Wherein, make sensor chip and control chip in same encapsulation body, sensor chip and control chip's distance is less than 100um. The sensor circuit and the control circuit comprise a switch array, an amplifying circuit, a filter circuit, a booster circuit, a charge pump circuit, a digital circuit and an analog circuit, wherein the switch array is composed of a diode, a transistor, a field effect transistor, a resistor, an inductor, a capacitor, a metal interconnection line, a dielectric layer and a passivation layer.

In S630, micro pads are provided on the surface of the silicon wafer.

A first bonding pad 705 and a passivation layer 715 are disposed on a surface of a silicon wafer 716, a micro-bonding pad 711 is disposed on the first bonding pad 705, the micro-bonding pad 711 includes a metal bump 713 and a solder 714, and then a non-conductive film (NCF) 712 is covered, referring to fig. 7, among the plurality of first bonding pads, a part of the first bonding pad 705 is connected to a first pixel electrode array, another part of the first bonding pad 705 is connected to an input end and an output end of a sensor circuit and/or a control circuit in a chip, and the first pixel electrode array, the input end and the output end of the sensor circuit and/or the control circuit are electrically connected to an external circuit through the micro-bonding pad 711, for example, the first pixel electrode array is electrically connected to a second pixel electrode array through the micro-bonding pad 711. The metal bump 713 is preferably copper or gold. Solder 714 comprising nickel, tin, silver, etc. may also be provided on top of the metal bump 713 for facilitating the subsequent soldering process. In order to improve connection reliability between the metal bump 713 and the first pad 714 of the chip, a thin metal layer of titanium, nickel, tungsten, etc. may be further disposed between the metal bump 713 and the first pad 703 as an Under Bump Metal (UBM), an adhesion layer, and/or a barrier layer. The height of the metal bump 713 is typically greater than 1 micron and less than 10 microns.

In S640, the fabricated silicon wafer is divided into individual chips.

Compared with the prior art, the embodiment of the application has the advantages that the distance between the control circuit and the sensor circuit is greatly shortened, the communication distance between the control circuit and the sensor circuit can be reduced, the module volume is reduced, and the assembly steps are reduced.

Fig. 8 is a schematic flow chart of fabricating a rewiring extension layer in an embodiment of the application, the method including some or all of the following steps.

In S810, a slide is selected.

As shown in fig. 9, the carrier 905 is preferably a silicon material, but may also be a glass material, a ceramic material, a metal plate material, an acryl material, or other rigid material. The carrier sheet may comprise a deposited layer, an oxide layer, and/or a bonding layer. The slide may be circular or square.

In S820, an insulating layer is provided on the carrier sheet.

The insulating layer 901 may be one or more of silicon oxide, silicon nitride, silicon carbide, silicon carbonitride, silicon oxynitride, silicon glass (SILICATEGLASS) grown using a chemical vapor deposition process (Chemical Vapor Deposition, CVD) or an atomic layer deposition process (Atomic layer deposition, ALD); and can also be one or more of Polyimide (PI), polybenzoxazole (PBO), benzocyclobutene (BCB) and spin-on glass (SOG) arranged in a coating process.

In S830, metal wirings are provided in the insulating layer.

The metal trace 902 may be aluminum and/or molybdenum grown by a physical vapor deposition process (Physical Vapor Deposition, PVD), or a composite conductive layer grown by PVD in combination with an electroplating process, the composite conductive layer comprising 2 or more of titanium, titanium nitride, tantalum nitride, copper. In some cases, the metal trace may also include 2 or more of platinum, silver, gold, nickel, palladium, tungsten, indium tin oxide, aluminum doped zinc oxide, indium doped zinc oxide, conductive ink, and conductive paste, with alternative processes including PVD, CVD, electroplating, electroless plating, coating, and the like. The patterning process of the metal wiring can be realized by photoetching and Damascus process, or can be realized by photoetching and wet etching, dry etching or stripping (Lift-off) process, or can be realized by ink-jet printing, laser direct writing or screen printing.

In 840, a second pad is disposed on the uppermost metal trace.

In the above steps, specifically, a layer of silicon oxide is grown on the surface of the carrier by CVD process as an insulating layer 901; then, growing metal titanium and/or copper on the silicon oxide, and patterning to obtain a first layer of metal wires, wherein the first layer of metal wires comprises a second pixel electrode array 904; then, using Damascus process, sequentially manufacturing 2,3 and 4 layers of metal wires and an insulating layer between layers. The specific layer number of the metal wires can be set according to actual requirements, and the metal wires of all layers are electrically connected with each other. In addition, a second pad 903 is required to be provided on the uppermost metal trace. The second bonding pad 903 may be formed directly using the pattern of the uppermost metal, or a further layer of copper may be grown and patterned to form the second bonding pad 903.

The rewiring extension layer includes an insulating layer 901, a metal wiring 902, a plurality of second pads 903, and a second pixel electrode array 904. The second pad 903 is located on the upper surface of the rewiring extension layer, the second pixel electrode array 904 is located on the lower surface of the rewiring extension layer, if the rewiring extension layer is inverted, the second pad 903 is located on the lower surface of the rewiring extension layer, the second pixel electrode array 904 is located on the upper surface of the rewiring extension layer, or the second pad 903 is located on the lower surface of the insulating layer 901, and the second pixel electrode array 904 is located on the upper surface of the insulating layer 901. The metal wire 902 is disposed in the insulating layer 901, one end of the metal wire 902 is electrically connected to the second pixel electrode in the second pixel electrode array 904, and the other end of the metal wire 902 is electrically connected to the first pixel electrode in the first pixel electrode array. The second pad 903 is electrically connected to the second pixel electrode array 904 through the metal trace 902. The second bonding pad is used for being welded on the micro-welding spot of the chip so as to realize that a plurality of second pixel electrodes of the second pixel electrode array are respectively connected with a plurality of first pixel electrodes of the first pixel electrode array. In some application scenarios, such as fingerprint recognition, because the distance between the valley and the ridge of the finger is about 100um, the interval between two adjacent second pixel electrodes in the second pixel electrode array is smaller than 100um, so as to perform fingerprint recognition. The second pad 903 is typically copper. In some cases, the second pad surface may have nickel and gold to prevent copper oxidation. In other cases, an additional thin metal layer is also provided between the second pad and the metal trace as UBM, adhesion layer and/or barrier layer.

Fig. 10 is a schematic flow chart of the interconnection of a chip with a rewiring expansion layer in an embodiment of the application, the method including some or all of the following steps.

In S1010, the chip is disposed on the rewiring extension layer.

As shown in fig. 11, the chip 1110 is soldered face down onto the rewiring extension 1120, the micro-pads 1104 of the chip 1110 are fixedly connected one by one with the second pads 1121 of the rewiring extension 1120, and the NCF1103 is cured. It should be noted that, instead of using the NCF1103, for example, after the micro pad 1104 and the second pad 1121 are welded, an insulating underfill may be injected into the gap between the micro pad 1104 and the second pad 1121 and cured. Wherein micro-pad 1104 includes metal bump 1102 and solder 1102. The plurality of second pixel electrodes in the second pixel electrode array 1123 and the plurality of first pixel electrodes in the first pixel electrode array 1105 are electrically connected one by one through the metal wiring 1122, and preferably, in order to improve reliability, a gap between the micro pad 1104 and the second pad 1121 may be filled with an insulating material.

In S1020, a plastic package case is provided on the chip surface.

Molding the surface of the chip by using an epoxy resin molding material (Epoxy Molding Compound, EMC) to form a plastic package shell, wherein the plastic package shell is positioned on the lower surface of the insulating layer;

in S1030, the carrier sheet is removed, exposing the second pixel electrode array in the rewiring extension layer.

For example, the slide is completely removed by mechanical grinding in combination with a wet etching process to expose the surface silicon oxide and obtain a reconstituted wafer. Next, a dry etching process is used to remove a portion of the silicon oxide to expose the original first layer of metal traces, where the first layer of metal traces includes the second pixel electrode array, i.e. expose the second pixel electrode array, as shown in fig. 12.

Fig. 13 is a schematic flow chart of disposing an acousto-electric conversion layer in an embodiment of the present application, the method including some or all of the following steps.

In S1310, a layer of piezoelectric material is disposed over the rewiring extension layer.

Wherein the coating process may be slot coating, spray coating or spin coating. The piezoelectric material is preferably a ferroelectric polymer including polyvinylidene fluoride (PVDF), PVDF-related copolymers such as vinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE), vinylidene fluoride-tetrafluoroethylene copolymer (PVDF-TFE).

Specifically, as shown in fig. 14, a patterned PVDF-TrFE material is coated on the surface of the rewiring extension layer by a screen printing process, and baked to cure, thereby forming a piezoelectric material layer 1401.

In 1320, an electrode layer is disposed on a surface of the piezoelectric material layer.

On the surface of the piezoelectric material layer 1401, a layer of conductive silver paste is screen-printed, and baked and cured as an electrode layer 1402. The electrode layer 1402 is connected to metal traces in the rewiring layer. And placing the reconstructed wafer with the prepared acoustic-electric conversion layer in a strong electric field to polarize PVDF-TrFE material, and then applying a required electric field to the piezoelectric material layer by the wiring extension layer to enable the piezoelectric material layer to have piezoelectric characteristics.

And finally, scribing the reconstructed wafer to obtain a plurality of ultrasonic sensors.

There are various ways to provide the acoustoelectric conversion layer, and in one implementation, a prefabricated piezoelectric material film with an electrode layer may be directly attached to the rewiring extension layer.

In one implementation, a conductive portion may also be provided on the rewiring extension layer, the conductive portion being connected to the metal trace. For example, the conductive portion may be a copper pillar or a conductive via.

The embodiment of the present application is described taking the conductive portion as a copper pillar as an example, as shown in fig. 15, before step 520, further includes:

S511, a copper column is arranged on the rewiring expansion layer.

Copper pillars 1601 are provided on the rewiring extension 1620 using photolithography, PVD, electroplating, wet etching processes, the copper pillars 1601 being connected with metal traces 1622, as shown in fig. 16.

As shown in fig. 17, in the process of interconnecting the chip and the rewiring extension layer, after step S1020, the method further includes:

s1021, removing part of the plastic package shell to expose the upper surface of the copper column.

In one implementation, a portion of the plastic package is removed by mechanical grinding to expose the upper surface of the copper pillar.

S1022, arranging an insulating layer on the upper surface of the plastic package shell

As shown in fig. 18, a layer of polyimide is coated on the surface of the plastic package casing 1802 with the copper pillar 1801 exposed to form an insulating layer 1803, and a notch is opened at the position of the copper pillar by photolithography to expose the copper pillar, wherein one end of the copper pillar is fixedly connected with the metal wire, and the other end of the copper pillar is connected with the third bonding pad 1804.

S1023, disposing a third bonding pad above the insulating layer.

And depositing metallic titanium and/or copper on the insulating layer, and patterning to obtain a third bonding pad. And the third bonding pad is positioned below the plastic package shell. The copper pillars 1801 are on the same side of the rewiring extension layer as the chip. Thereafter, referring to the above embodiment, an acoustic-electric conversion layer is formed, and an ultrasonic sensor 1900 after the acoustic-electric conversion layer is formed is shown in fig. 19.

After the ultrasonic sensor is formed, the ultrasonic sensor is connected with the FPC to form an ultrasonic fingerprint module, as shown in FIG. 20, a copper post 2001 of the ultrasonic sensor 2000 is electrically connected with the FPC2005 through a third bonding pad 2004 by using conductive adhesive (not shown), and the ultrasonic fingerprint recognition module is obtained. The FPC2005 includes a soldered jack, an interface, and a passive element thereon.

As shown in fig. 21, after the ultrasonic fingerprint recognition module is fabricated, one surface of an acoustic-electric conversion layer of an ultrasonic sensor is attached to the back surface of a screen or cover 2120 by an adhesive layer 2110. The ultrasonic sensor emits signals by coupling electric signals to the piezoelectric material layer 2103 through the first pixel electrode array 2102 and the second pixel electrode array 2101 under the driving of a sensor circuit in a chip, so that the piezoelectric material layer 2103 is correspondingly deformed and vibrated at high frequency, and ultrasonic waves are emitted; the ultrasonic sensor receives signals, namely ultrasonic waves reflected by an external object 2130 (such as a finger) to be imaged, deforms and vibrates the piezoelectric material layer 2103 under the action of sound pressure, generates corresponding electric signals, and transmits the electric signals to a sensor circuit in the chip through the second pixel electrode array 2102 and the first pixel electrode array 2102.

The embodiment of the present application is described by taking the conductive portion as the vertical conductive channel as an example, and as shown in fig. 22-25, in the process of interconnecting the chip and the rewiring extension layer, after step 1020, the method further includes:

S1021, arranging a vertical conductive channel inside the plastic package shell;

And forming a blind hole penetrating through the plastic package shell by utilizing the laser to punch the plastic package shell, wherein the bottom of the blind hole exposes the second bonding pad 2706. Pressing conductive silver paste into the blind hole, and solidifying to form a vertical conductive channel;

s1022, an insulating layer 2501 and a third pad 2502 of the vertical conductive channel are fabricated.

In one embodiment, as shown in fig. 26-27, an insulating layer 2601 may be first covered on the surface of the plastic package, then an adhesion layer and a seed layer are directly formed on the sidewall of the blind via and the insulating layer by PVD process, and finally the vertical conductive via 2703 and the third pad 2702 are obtained by electroplating and patterning. One end of the vertical conductive channel 2703 is fixedly connected with the second bonding pad 2706, and the other end of the vertical conductive channel 2703 is connected with a third bonding pad 2702. The vertical conductive vias are disposed below the rewiring extension layer and on the same side of the chip.

In one embodiment, the pre-fabricated vertical conductive vias 2801 may also be soldered directly to the rewiring extension layer, as shown in fig. 28, including via structures fabricated using PCB technology or through-silicon vias (Through Silicon Via, TSV) fabricated using semiconductor technology, and finally a molding process is used to form a plastic package case 2902 over the rewiring extension layer, as shown in fig. 29, where the vertical conductive vias 2801 are fixedly connected to the second bonding pads 2806. Vertical conductive vias 2801 are disposed under the rewiring extension layer and on the same side of the chip.

Unlike the embodiment of fig. 20, as shown in fig. 30, after the ultrasonic fingerprint recognition module is fabricated, since the electrode layer 3020 is not directly connected to the metal trace, an additional conductive structure 3010 is used to connect the electrode layer and the FPC3005, for example, the conductive structure 3010 may be a conductive tape, so as to implement grounding of the electrode layer 3020 through the FPC, thereby omitting the patterning step of the piezoelectric material layer.

And one end of the conductive part is connected with the rewiring expansion layer, and the other end of the conductive part is connected with a third bonding pad positioned below the plastic package shell, so that multiple processes are involved, and the cost is high. In another embodiment, as shown in fig. 31-33, copper pillars are disposed above and electrically connected to the rewiring extension layer, the copper pillars extend away from the chip for electrically connecting the ultrasonic sensor to the FPC, whereby, when the module is assembled, the FPC3220 is disposed between the ultrasonic sensor and the screen, and the FPC3220 is fixedly connected to one end of the copper pillars and the electrode layer by conductive paste and is attached to the screen or under the cover plate 3330 by the adhesive layer 3310.

Embodiments of the present application also provide an ultrasonic sensor, as shown in fig. 34, where multiple chips may be molded together, for example, chip 3410 and chip 3420 may be molded in a single plastic package, and in one embodiment, chip 3410 may be a sensor chip and chip 3420 may be a control chip. The interval between the sensor chip and the control chip is smaller than 100um. By re-routing the extension layer to effect extension from the first pixel electrode array to the second pixel electrode array, pads between the chip 3410 and the chip 3420 may be connected by metal traces 3430 in the re-routing extension layer to effect communication between the different chips.

The application also provides a fingerprint identification module which can comprise a flexible circuit board and the ultrasonic sensor in any embodiment of the application.

In one possible implementation manner, the ultrasonic sensor further comprises a conductive part arranged in the plastic package shell, one end of the conductive part is electrically connected with the rewiring expansion layer, and the other end of the conductive part is connected with a third bonding pad positioned below the plastic package shell.

In one possible implementation, the ultrasonic sensor further includes a copper pillar disposed above and electrically connected to the rewiring extension layer, the copper pillar extending away from the chip for electrically connecting the ultrasonic sensor to the FPC, wherein the copper pillar is a conductive portion.

In one possible implementation, the flexible circuit board is disposed below the ultrasonic sensor.

In one possible implementation, the acoustic-to-electric conversion layer includes an electrode layer, the flexible circuit board is fixedly connected to the third pad, and the flexible circuit board is fixedly connected to the electrode layer through a conductive structure.

In one possible implementation manner, the acoustoelectric conversion layer includes an electrode layer, the flexible circuit board is fixedly connected with the third pad, and the electrode layer is connected with the second pixel electrode.

In one possible implementation, the flexible circuit board is disposed between the ultrasonic sensor and the screen.

In one possible implementation manner, the sound-electricity conversion layer comprises an electrode layer, and the flexible circuit board is fixedly connected with one end of the copper pillar and the electrode layer, wherein the copper pillar is a conductive part.

The application also provides electronic equipment which can comprise a screen and the fingerprint identification module in any embodiment of the application, wherein the screen is connected with the flexible circuit board through the bonding layer.

It should be noted that, on the premise of no conflict, the embodiments and/or technical features in the embodiments described in the present application may be combined with each other arbitrarily, and the technical solutions obtained after combination should also fall into the protection scope of the present application.

The system, the device and the method disclosed in the embodiments of the present application may be implemented in other manners. For example, some features of the method embodiments described above may be omitted or not performed. The above-described apparatus embodiments are merely illustrative, and the division of units is merely one logical function division, and there may be another division manner in actual implementation, and a plurality of units or components may be combined or may be integrated into another system. In addition, the coupling between the elements or the coupling between the elements may be direct or indirect, including electrical, mechanical, or other forms of connection.

It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working processes and technical effects of the apparatus and device described above may refer to corresponding processes and technical effects in the foregoing method embodiments, which are not described in detail herein.

It should be understood that the specific examples in the embodiments of the present application are intended to help those skilled in the art to better understand the embodiments of the present application, and not to limit the scope of the embodiments of the present application, and that those skilled in the art may make various modifications and variations on the basis of the above embodiments, and that these modifications or variations fall within the scope of the present application.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An ultrasonic sensor for effecting conversion between an ultrasonic signal and an electrical signal, comprising:

The chip comprises a first pixel electrode array, wherein the first pixel electrode array comprises a plurality of first pixel electrodes which are arranged in an array manner;

The rewiring expansion layer is arranged above the chip and comprises a second pixel electrode array, the second pixel electrode array comprises a plurality of second pixel electrodes, the second pixel electrodes are arranged in an array mode, the second pixel electrodes are respectively connected with the first pixel electrodes, and the area of the second pixel electrode array is larger than that of the first pixel electrode array, so that the area of a fingerprint identification area is larger than that of the chip;

The sound-electricity conversion layer is used for converting ultrasonic signals and electric signals, the sound-electricity conversion layer is arranged above the rewiring extension layer and comprises a piezoelectric material layer and an electrode layer, and the piezoelectric material layer is arranged between the electrode layer and the second pixel electrode array and fixedly connected with the second pixel electrode array.

2. The ultrasonic sensor according to claim 1, wherein the rewiring extension layer includes an insulating layer and a metal wiring, the second pixel electrode array is disposed on an upper surface of the insulating layer, the metal wiring is disposed in the insulating layer, and the plurality of second pixel electrodes are respectively connected to the plurality of first pixel electrodes through the metal wiring.

3. The ultrasonic sensor of claim 2, wherein the rewiring extension layer further comprises a second pad located on a lower surface of the insulating layer, the second pad being for connection with the first pixel electrode and for connection with the second pixel electrode through the metal trace.

4. An ultrasonic transducer according to claim 3, wherein the first pixel electrode is provided with micro-pads for connection with the second pixel electrode.

5. The ultrasonic sensor of claim 4, wherein the second bond pad is fixedly coupled to the micro-pad.

6. The ultrasonic sensor of claim 1, wherein a spacing between adjacent two of the second pixel electrodes is less than 100um.

7. The ultrasonic sensor of claim 2, further comprising a plastic package housing located on a lower surface of the insulating layer, the plastic package housing encasing the chip.

8. The ultrasonic sensor of claim 7, further comprising a conductive portion disposed in the plastic enclosure, one end of the conductive portion being connected to the rewiring expansion layer and the other end of the conductive portion being connected to a third bonding pad located below the plastic enclosure.

9. The ultrasonic sensor of claim 7, further comprising a copper post disposed above and electrically connected to the rewiring extension layer, the copper post extending away from the chip for electrically connecting the ultrasonic sensor to an FPC, wherein the copper post is a conductive portion.

10. The ultrasonic sensor of claim 2, wherein the chip comprises a sensor chip.

11. The ultrasonic sensor of claim 10, wherein the chip further comprises a control chip, the sensor chip being spaced less than 100um from the control chip.

12. The ultrasonic sensor of claim 11, wherein communication between the sensor chip and the control chip is via the metal trace.

13. The utility model provides a fingerprint identification module which characterized in that includes: a flexible circuit board and an ultrasonic sensor according to any one of claims 1 to 6.

14. The fingerprint recognition module of claim 13, wherein the ultrasonic sensor further comprises a conductive portion disposed in the plastic package, one end of the conductive portion being electrically connected to the rewiring extension layer, and the other end of the conductive portion being connected to a third pad located under the plastic package.

15. The fingerprint recognition module of claim 13, wherein the ultrasonic sensor further comprises a copper post disposed above and electrically connected to the rewiring extension layer, the copper post extending away from the chip for electrically connecting the ultrasonic sensor to the FPC, wherein the copper post is a conductive portion.

16. The fingerprint recognition module of claim 14 or 15, wherein the flexible circuit board is disposed below the ultrasonic sensor.

17. The fingerprint recognition module of claim 16, wherein the flexible circuit board is fixedly connected to the third bonding pad, and wherein the flexible circuit board is fixedly connected to the electrode layer via a conductive structure.

18. The fingerprint recognition module of claim 16, wherein the flexible circuit board is fixedly connected to a third pad, and the electrode layer is connected to the second pixel electrode.

19. The fingerprint recognition module of claim 14, wherein the flexible circuit board is disposed between the ultrasonic sensor and a screen.

20. The fingerprint recognition module of claim 19, wherein the acousto-electric conversion layer comprises an electrode layer, the flexible circuit board is fixedly connected with one end of a copper pillar and the electrode layer, and the copper pillar is a conductive part.

21. An electronic device, comprising: a screen and a fingerprint recognition module according to claim 13 or 20, the screen being connected to the flexible circuit board by an adhesive layer.