CN117935321A - Fingerprint identification module and manufacturing method thereof - Google Patents

Abstract

The invention discloses a fingerprint identification module and a manufacturing method thereof, wherein the fingerprint identification module comprises: a driving substrate and a plurality of fingerprint recognition units connected to the driving substrate; the fingerprint identification unit comprises an ultrasonic wave transmitting device and an ultrasonic wave receiving device, wherein the ultrasonic wave transmitting device is used for transmitting ultrasonic waves to the fingerprint, and the ultrasonic wave receiving device is used for receiving the ultrasonic waves which are transmitted by the ultrasonic wave transmitting device in the same fingerprint identification unit and reflected by the fingerprint; the ultrasonic wave transmitting device adopts a capacitive ultrasonic transducer, so that the transmitting intensity of ultrasonic signals can be improved, and the ultrasonic wave receiving device adopts a piezoelectric ultrasonic transducer, so that the ultrasonic wave transmitting device has better deformation capability, and the receiving capability of the ultrasonic signals can be improved, thereby improving the imaging definition of the fingerprint identification unit.

Description

Fingerprint identification module and manufacturing method thereof

Technical Field

The invention relates to the technical field of ultrasonic waves, in particular to a fingerprint identification module and a manufacturing method thereof.

Background

The ultrasonic fingerprint recognition technology is a technology for realizing fingerprint recognition based on the propagation and reflection of ultrasonic waves in an object, when a finger presses the surface of a device, an ultrasonic sensor emits ultrasonic waves to a region pressed by the finger, and when the ultrasonic waves contact with the valley and the ridge of the fingerprint, the ultrasonic waves are absorbed, penetrated and reflected to different degrees, so that ultrasonic signals reflected back to the ultrasonic sensor have different energies, and the ultrasonic signals can be converted into electric signals in the ultrasonic sensor so as to form fingerprint patterns. Therefore, the intensity of the ultrasonic signals transmitted and received by the ultrasonic sensor directly affects the imaging definition of the fingerprint, and at present, how to improve the imaging definition of the fingerprint pattern is a problem that needs to be focused in the fingerprint identification process.

Disclosure of Invention

The invention provides a fingerprint identification module and a manufacturing method thereof, which are used for improving imaging definition of fingerprint identification.

In a first aspect, the present invention provides a fingerprint identification module, including: a driving substrate and a plurality of fingerprint recognition units connected to the driving substrate;

The fingerprint identification unit comprises an ultrasonic wave transmitting device and an ultrasonic wave receiving device, wherein the ultrasonic wave transmitting device is used for transmitting ultrasonic waves to a fingerprint, and the ultrasonic wave receiving device is used for receiving the ultrasonic waves transmitted by the ultrasonic wave transmitting device in the same fingerprint identification unit and reflected by the fingerprint;

The ultrasonic transmitting device adopts a capacitive ultrasonic transducer, and the ultrasonic receiving device adopts a piezoelectric ultrasonic transducer.

In some embodiments of the present invention, the fingerprint identification module further includes a dielectric layer, where the dielectric layer includes a dielectric portion and a plurality of hollowed-out portions; the medium part is used for isolating the ultrasonic transmitting device and the ultrasonic receiving device which are adjacent, and the hollowed-out part is used for arranging the ultrasonic transmitting device and the ultrasonic receiving device.

In some embodiments of the invention, the ultrasonic wave emitting device includes: a first electrode, a diaphragm and a second electrode; the vibrating diaphragm is positioned at one side of the first electrode, which is away from the driving substrate, and a first cavity is formed between the vibrating diaphragm and the first electrode; the second electrode is positioned at one side of the vibrating diaphragm, which is away from the first electrode, and is in contact with the vibrating diaphragm;

And the orthographic projection of the vibrating diaphragm on the driving substrate and the orthographic projection of the adjacent medium part on the driving substrate are overlapped.

In some embodiments of the invention, the ultrasonic receiving device comprises: a third electrode, a piezoelectric layer, and a fourth electrode; the piezoelectric layer is positioned on one side of the third electrode, which is away from the driving substrate, and the fourth electrode is positioned on one side of the piezoelectric layer, which is away from the third electrode.

In some embodiments of the invention, the ultrasonic receiving device comprises: a third electrode, a fourth electrode, a piezoelectric layer, and a fifth electrode; the fourth electrode is positioned at one side of the third electrode, which is away from the driving substrate, a second cavity is formed between the third electrode and the fourth electrode, the third electrode is connected with the fourth electrode, the piezoelectric layer is positioned at one side of the fourth electrode, which is away from the second cavity, and the fifth electrode is positioned at one side of the piezoelectric layer, which is away from the fourth electrode;

and the orthographic projection of the fourth electrode on the driving substrate and the orthographic projection of the adjacent medium part on the driving substrate are overlapped.

In some embodiments of the present invention, the dielectric layer further includes a plurality of vias, the vias extending through the dielectric portion;

The ultrasonic receiving device further comprises an electrode connecting portion, wherein the electrode connecting portion is located in a through hole of the medium portion adjacent to the second cavity, and the electrode connecting portion is used for connecting the third electrode and the fourth electrode.

In some embodiments of the invention, each of the diaphragms and each of the fourth electrodes are arranged in the same layer.

In some embodiments of the invention, each of the first electrodes is disposed on the same layer as each of the third electrodes.

In some embodiments of the present invention, the dielectric layer is a negative photoresist, and the material of the negative photoresist includes polystyrene.

In some embodiments of the present invention, the piezoelectric layer is made of a material including one or more of piezoelectric ceramics, aluminum nitride, zinc oxide, and polyvinylidene fluoride.

In a second aspect, the present invention further provides a method for manufacturing a fingerprint identification module, where the method for manufacturing a fingerprint identification module includes:

providing a driving substrate;

Forming a plurality of fingerprint recognition units on the driving substrate; the fingerprint identification unit comprises an ultrasonic transmitting device and an ultrasonic receiving device, wherein the ultrasonic transmitting device adopts a capacitive ultrasonic transducer, and the ultrasonic receiving device adopts a piezoelectric ultrasonic transducer.

In some embodiments of the present invention, the forming a plurality of fingerprint recognition units on the driving substrate includes:

Forming a plurality of first electrodes and a plurality of third electrodes on the driving substrate;

Forming a dielectric layer on the first electrodes and the third electrodes;

Forming a plurality of vibrating diaphragms and a plurality of fourth electrodes on the dielectric layer; the fourth electrodes are connected with the third electrodes in a one-to-one correspondence manner;

Etching the dielectric layer to form a plurality of first cavities and a plurality of second cavities; the plurality of first cavities are in one-to-one correspondence with the plurality of diaphragms, and orthographic projection of the diaphragms on the driving substrate covers orthographic projection of the first cavities on the driving substrate; the second cavities are in one-to-one correspondence with the fourth electrodes, and orthographic projection of the fourth electrodes on the driving substrate covers orthographic projection of the second cavities on the driving substrate;

Forming a piezoelectric layer on the fourth electrode;

Forming a second electrode on the diaphragm and a fifth electrode on the piezoelectric layer; the ultrasonic wave emitting device comprises the first electrode, the first cavity, the vibrating diaphragm and the second electrode; the ultrasonic wave receiving device comprises the third electrode, the fourth electrode, the piezoelectric layer and the fifth electrode, and the fourth electrode is connected with the third electrode.

In some embodiments of the present invention, the forming a plurality of fingerprint recognition units on the driving substrate includes:

forming a plurality of first electrodes and a plurality of third electrodes on a driving substrate;

forming a piezoelectric layer on the third electrode;

Forming a dielectric layer on the plurality of first electrodes and the driving substrate; the dielectric layer comprises a plurality of hollowed-out parts, and the piezoelectric layer is positioned in the hollowed-out parts;

Forming a plurality of vibrating diaphragms and a plurality of fourth electrodes on the dielectric layer; the plurality of vibrating diaphragms are in one-to-one correspondence with the plurality of first electrodes, and the plurality of fourth electrodes are in one-to-one correspondence with the plurality of third electrodes; the ultrasonic wave receiving device comprises the third electrode, the piezoelectric layer and the fourth electrode;

Etching the dielectric layer to form a plurality of first cavities; the plurality of first cavities are in one-to-one correspondence with the plurality of diaphragms, and orthographic projection of the diaphragms on the driving substrate covers orthographic projection of the first cavities on the driving substrate;

Forming a second electrode on the diaphragm; the ultrasonic wave emitting device includes the first electrode, the first cavity, the diaphragm, and the second electrode.

The invention has the following beneficial effects:

The invention provides a fingerprint identification module and a manufacturing method thereof, wherein the fingerprint identification module comprises: a driving substrate and a plurality of fingerprint recognition units connected to the driving substrate; the fingerprint identification unit comprises an ultrasonic wave transmitting device and an ultrasonic wave receiving device, wherein the ultrasonic wave transmitting device is used for transmitting ultrasonic waves to the fingerprint, and the ultrasonic wave receiving device is used for receiving the ultrasonic waves which are transmitted by the ultrasonic wave transmitting device in the same fingerprint identification unit and reflected by the fingerprint; the ultrasonic wave transmitting device adopts a capacitive ultrasonic transducer, so that the transmitting intensity of ultrasonic signals can be improved, and the ultrasonic wave receiving device adopts a piezoelectric ultrasonic transducer, so that the ultrasonic wave transmitting device has better deformation capability, and the receiving capability of the ultrasonic signals can be improved, thereby improving the imaging definition of the fingerprint identification unit.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of the overall structure of a fingerprint recognition module according to an embodiment of the present invention;

fig. 2 is a cross-sectional view of a fingerprint recognition module according to an embodiment of the present invention;

Fig. 3 is a schematic structural diagram of a fingerprint identification module in a manufacturing process according to an embodiment of the present invention;

Fig. 4 is a schematic structural diagram of a fingerprint identification module according to an embodiment of the present invention in a manufacturing process;

fig. 5 is a schematic structural diagram of a fingerprint identification module according to an embodiment of the present invention in a manufacturing process;

FIG. 6 is a top view of the fingerprint recognition module of FIG. 5 during the manufacturing process;

fig. 7 is a schematic structural diagram of a fingerprint identification module in a manufacturing process according to an embodiment of the present invention;

Fig. 8 is a schematic structural diagram of a fingerprint identification module according to an embodiment of the present invention in a manufacturing process;

Fig. 9 is a schematic structural diagram of a fingerprint identification module in a manufacturing process according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of a fingerprint identification module according to an embodiment of the present invention in a manufacturing process;

FIG. 11 is a cross-sectional view of a fingerprint recognition module according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of a fingerprint recognition module in a manufacturing process according to an embodiment of the present invention;

fig. 13 is a schematic structural diagram of a fingerprint identification module according to an embodiment of the present invention in a manufacturing process;

FIG. 14 is a top view of the fingerprint recognition module of FIG. 13 during the manufacturing process;

fig. 15 is a schematic structural diagram of a fingerprint identification module according to an embodiment of the present invention in a manufacturing process;

fig. 16 is a schematic structural diagram of a fingerprint recognition module in a manufacturing process according to an embodiment of the present invention;

FIG. 17 is a schematic diagram of a fingerprint recognition module according to an embodiment of the present invention in a manufacturing process;

reference numerals illustrate:

The driving circuit comprises a driving substrate 1, a base 11, a driving circuit 12, a fingerprint identification unit Q, an ultrasonic wave emitting device T, a first electrode TX1, a first cavity 31, a vibrating diaphragm 32, a second electrode TX2, an ultrasonic wave receiving device R, a third electrode RX1, a second cavity 41, a fourth electrode RX2, a piezoelectric layer 42, a fifth electrode RX3, an electrode connecting part 43, a dielectric layer 2, a dielectric part 21, a hollowed part 22, a packaging layer 5, a first direction X and a second direction Y.

Detailed Description

In order that the above objects, features and advantages of the invention will be readily understood, a further description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. However, the exemplary embodiments can be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus a repetitive description thereof will be omitted. The words expressing the positions and directions described in the present invention are described by taking the drawings as an example, but can be changed according to the needs, and all the changes are included in the protection scope of the present invention. The drawings of the present invention are merely schematic representations of relative positional relationships and are not intended to represent true proportions.

The fingerprint identification module provided by the embodiment of the invention can be applied to a fingerprint identification device or a display device with fingerprint identification function requirements, such as a mobile phone, a tablet personal computer and the like. The fingerprint identification module provided by the embodiment of the invention is based on the ultrasonic fingerprint identification technology, and can be arranged in a display area of a display device or can be arranged in a non-display area such as a side surface and a back surface of the display device. The fingerprint recognition module may be disposed in a portion of the display area of the display device, to implement a fingerprint recognition function in a set area, or may be disposed in an entire display area of the display device, to implement a fingerprint recognition function in any position of the display device. It can be appreciated that the specific application scenario of the fingerprint identification module can be determined according to the product requirement, and the specific application scenario is not limited herein.

Fig. 1 is a schematic diagram of an overall structure of a fingerprint identification module according to an embodiment of the present invention.

As shown in fig. 1, in an embodiment of the present invention, a fingerprint identification module includes: a drive substrate 1 and a plurality of fingerprint recognition units Q connected to the drive substrate 1. The fingerprint identification unit Q includes an ultrasonic transmitting device T and an ultrasonic receiving device R, where the ultrasonic transmitting device T is used to transmit sound waves to the fingerprint, the ultrasonic receiving device R is used to receive ultrasonic waves, the ultrasonic transmitting device T and the ultrasonic receiving device R both adopt ultrasonic transducers, and the driving circuit 12 on the driving substrate 1 applies voltage to the ultrasonic transducers, so that conversion between electric energy and mechanical energy can be realized in the ultrasonic transducers.

The plurality of ultrasonic transducers may be arrayed in the first direction X and the second direction Y on the driving substrate 1, and in the first direction X, the ultrasonic wave transmitting devices T and the ultrasonic wave receiving devices R are alternately arrayed, and in the second direction Y, the ultrasonic wave transmitting devices T and the ultrasonic wave receiving devices R are also alternately arrayed. Like this, every ultrasonic wave transmitting device T all is ultrasonic wave receiving device R adjacent device all around, ultrasonic wave transmitting device T and every adjacent ultrasonic wave receiving device R all can constitute a fingerprint identification unit Q to the ultrasonic wave that this ultrasonic wave transmitting device T transmitted can be received by the ultrasonic wave receiving device R in same fingerprint identification unit Q after being reflected by the fingerprint, has reduced the crosstalk of ultrasonic wave signal between the adjacent fingerprint identification unit Q from this, is favorable to promoting fingerprint identification module's SNR, and then improves fingerprint imaging's definition and imaging quality.

The ultrasonic transmitting device T adopts a capacitive ultrasonic transducer (capacitor micromechanical ultrasonic transducer, abbreviated as CMUT) to improve the transmitting intensity of ultrasonic signals, and the ultrasonic receiving device R adopts a piezoelectric ultrasonic transducer (piezoelectric micromachined ultrasonic transducer, abbreviated as PMUT) to enable the ultrasonic receiving device to have better deformation capability and improve the receiving capability of the ultrasonic signals.

Fig. 2 is a cross-sectional view of a fingerprint recognition module according to an embodiment of the present invention.

Fig. 2 may correspond to a cross-sectional view along the AA' direction in fig. 1, and as shown in fig. 2, in an embodiment of the present invention, the fingerprint identification module may include: a drive substrate 1, a plurality of fingerprint recognition units Q, a dielectric layer 2 and an encapsulation layer 5.

The driving substrate 1 includes a base 11 and a driving circuit 12 disposed on a surface of the base 11, and illustratively, the base 11 may employ one or more of various types of TFT devices including, but not limited to, a silicon (Si) base 11, a glass base 11, etc., the driving circuit 12 may employ a thin film transistor (Thin Film Transistor, abbreviated as TFT) driving circuit 12, the TFT devices including a Gate (Gate), a source/drain (S/D), and an Active layer (Active), and the Active layer materials thereof may be classified into an oxide thin film transistor (Oxide Thin Film Transistor), a low temperature polysilicon thin film transistor (Low Temperature Poly-silicon Thin Film Transistor, abbreviated as LTPS TFT), a low temperature polysilicon oxide thin film transistor (Low Temperature Polycrystalline Oxide Thin Film Transistor, abbreviated as LTPO), etc. The device structure, circuit connection relation, etc. of the driving circuit 12 can be designed according to the requirements, and the embodiment of the present invention is not limited herein.

The fingerprint recognition unit Q includes an ultrasonic wave transmitting device T and an ultrasonic wave receiving device R. The dielectric layer 2 includes a dielectric portion 21 and a plurality of hollow portions 22, and the dielectric portion 21 can be used for isolating adjacent ultrasonic transmitting devices T and ultrasonic receiving devices R to avoid crosstalk generated by ultrasonic signals of adjacent ultrasonic transducer devices, and the hollow portions 22 are used for setting the ultrasonic transmitting devices T and the ultrasonic receiving devices R.

In the embodiment of the present invention, the ultrasonic wave transmitting device T includes: the driving circuit comprises a first electrode TX1, a vibrating diaphragm 32 and a second electrode TX2, wherein the vibrating diaphragm 32 is positioned on one side of the first electrode TX1, which is away from the driving substrate 1, a first cavity 31 is formed between the vibrating diaphragm 32 and the first electrode TX1, the second electrode TX2 is positioned on one side of the vibrating diaphragm 32, which is away from the first electrode TX1, and is in contact with the vibrating diaphragm 32, and the first electrode TX1 and the second electrode TX2 are respectively connected to the driving circuit 12.

The ultrasonic transmitting device T is a capacitive ultrasonic transducer (CMUT), a voltage is applied to the first electrode TX1 and the second electrode TX2, the diaphragm 32 can be deformed under the driving of the capacitive force between the first electrode TX1 and the second electrode TX2, the first cavity 31 provides a space for the diaphragm 32 to deform, and thus the diaphragm 32 vibrates in the first cavity 31 to transmit an ultrasonic signal.

For example, the second electrode TX2 of each ultrasonic wave transmitting device T may be grounded, and when transmitting an ultrasonic wave signal, a voltage signal having a certain magnitude may be applied to the first electrode TX1 through the driving circuit 12, and the magnitude of the voltage signal applied to each first electrode TX1 may be the same, so that the diaphragm 32 in each ultrasonic wave transmitting device T is simultaneously driven to vibrate and transmit the ultrasonic wave signal.

In the ultrasonic emission device T provided in the embodiment of the present invention, the front projection of the diaphragm 32 on the driving substrate 1 covers the front projection of the first cavity 31 on the driving substrate 1, and the front projection of the diaphragm 32 on the driving substrate 1 and the front projection of the adjacent dielectric portion 21 on the driving substrate 1 have overlapping portions, so that the dielectric portion 21 can have a supporting effect on the diaphragm 32, so that the diaphragm 32 and the second electrode TX2 are not easy to collapse, which is beneficial to improving the stability of the ultrasonic emission device T, and further the diaphragm 32 of the ultrasonic emission device T can vibrate to a greater extent, thereby improving the intensity of the ultrasonic signal emitted by the diaphragm.

In the embodiment of the present invention, the ultrasonic receiving device R includes: a third electrode RX1, a fourth electrode RX2, a piezoelectric layer 42, and a fifth electrode RX3. The fourth electrode RX2 is located at a side of the third electrode RX1 facing away from the driving substrate 1 with the second cavity 41 between the third electrode RX1 and the fourth electrode RX2, the third electrode RX1 is connected to the driving circuit 12, the fourth electrode RX2 is connected to the third electrode RX1 to be connected to the driving circuit 12, and illustratively, a via hole penetrating the dielectric part 21 may be provided in the dielectric part 21 adjacent to the fourth electrode RX2 and the third electrode RX1, the electrode connection part 43 is located in the via hole, and a depth of the via hole, i.e., a height of the electrode connection part 43 is the same as the depths of the first cavity 31 and the second cavity 41, and the electrode connection part 43 may be used to connect the fourth electrode RX2 and the third electrode RX1. The piezoelectric layer 42 is located on a side of the fourth electrode RX2 facing away from the second cavity 41, and illustratively, the material of the piezoelectric layer 42 may be one or more of piezoelectric ceramic, aluminum nitride (AlN), zinc oxide (ZnO), polyvinylidene fluoride (polyvinylidene difluoride, abbreviated as PVDF), and the piezoelectric material has a characteristic that a potential difference is generated between both end surfaces thereof when the piezoelectric material is mechanically deformed by pressure, that is, a piezoelectric effect. The fifth electrode RX3 is located on the side of the piezoelectric layer 42 facing away from the fourth electrode RX2, and the fifth electrode RX3 is connected to the driving circuit 12.

The ultrasonic receiving device R is a piezoelectric ultrasonic transducer (PMUT), the ultrasonic signal emitted from the ultrasonic emitting device T is reflected to the ultrasonic receiving device R and deforms the piezoelectric layer 42, and based on the piezoelectric effect of the piezoelectric material, an electrical signal is generated between the fifth electrode RX3 and the fourth electrode RX2, and is transmitted to the driving circuit 12 through the fifth electrode RX3 and the third electrode RX 1.

For example, the fifth electrode RX3 in each of the ultrasonic wave receiving devices R may be grounded, the electric signal generated by the piezoelectric layer 42 is transmitted to the driving circuit 12 through the fourth electrode RX2 and the third electrode RX1, and since the magnitudes of the ultrasonic wave signals reflected by the "valley" and the "ridge" of the finger are different, the magnitudes of the electric signals transmitted to the driving circuit 12 by the different ultrasonic wave receiving devices R are also different, and the imaging of the "valley" and the "ridge" may be performed through the processing of the driving circuit 12, thereby forming the fingerprint image.

In the ultrasonic receiving device R provided by the embodiment of the invention, the second cavity 41 provides a deformable space for the piezoelectric layer 42 and the fourth electrode RX2, and the piezoelectric layer 42 can vibrate to a greater extent, so that the size of the received electric signal can be improved, and the definition and imaging speed of fingerprint imaging can be improved.

In the ultrasonic receiving device R provided in the embodiment of the present invention, the orthographic projection of the fourth electrode RX2 on the driving substrate 1 covers the orthographic projection of the second cavity 41 on the driving substrate 1, and the orthographic projection of the fourth electrode RX2 on the driving substrate 1 and the orthographic projection of the adjacent dielectric portion 21 on the driving substrate 1 have overlapping portions, so that the dielectric portion 21 can have a supporting effect on the fourth electrode RX2, so that the fourth electrode RX2, the piezoelectric layer 42 and the fifth electrode RX3 are not easy to collapse, which is beneficial to improving the stability of the ultrasonic transmitting device T.

In the embodiment of the invention, each vibrating diaphragm 32 and each fourth electrode RX2 can be arranged in the same layer, each first electrode TX1 and each third electrode RX1 can also be arranged in the same layer, the depth of each first cavity 31 and the depth of each second cavity 41 can be the same, which is beneficial to reducing the thickness of the fingerprint identification module and meets the requirement of the light and thin design of the product.

According to the same inventive concept, the embodiment of the invention also provides a manufacturing method of the fingerprint identification module. The invention also provides a manufacturing method of the fingerprint identification module, which comprises the following steps: providing a driving substrate 1, and forming a plurality of fingerprint recognition units Q on the driving substrate 1, wherein the fingerprint recognition units Q comprise an ultrasonic transmitting device T and an ultrasonic receiving device R, the ultrasonic transmitting device T adopts a capacitive ultrasonic transducer, and the ultrasonic receiving device R adopts a piezoelectric ultrasonic transducer.

Specifically, the method for manufacturing the fingerprint identification module may include the following steps S11 to S18, and the fingerprint identification module shown in fig. 2 may be formed after the following steps are completed.

Step S11: a drive substrate 1 is formed. The driving substrate 1 may be manufactured by a semiconductor manufacturing process, and referring to fig. 3, for example, fig. 3 is a schematic structural diagram of a fingerprint identification module in a manufacturing process according to an embodiment of the present invention, where the driving substrate 1 includes a substrate 11 and a driving circuit 12, and the driving circuit 12 is a TFT driving circuit, and the manufacturing process is as follows: forming a Buffer layer Buffer on the substrate 11; depositing an Active layer material on the Buffer layer Buffer and patterning the Active layer material to form Active layers of the TFT devices; forming a Gate dielectric layer GI on each Active layer Active, depositing a Gate material on the Gate dielectric layer GI and patterning the Gate material to form a Gate of each TFT device; forming an interlayer dielectric layer ILD on each Gate; depositing source and drain electrode materials on the interlayer dielectric layer ILD and patterning the source and drain electrode materials to form source electrodes S and drain electrodes D of the TFT devices, wherein the source electrodes S and the drain electrodes D of the TFT devices are respectively connected to corresponding Active layers through via holes in the interlayer dielectric layer ILD; a flat layer PLN1 is formed on each of the source electrode S and the drain electrode D.

Step S12: a plurality of first electrodes TX1 and a plurality of third electrodes RX1 are formed on the driving substrate 1. Referring to fig. 4, fig. 4 is a schematic structural diagram of a fingerprint recognition module in a manufacturing process according to an embodiment of the present invention, a plurality of first electrodes TX1 and a plurality of third electrodes RX1 may be formed by depositing and patterning a conductive material on a flat layer of a driving substrate 1, the conductive material may be a metal material including, but not limited to, copper, aluminum, silver, etc., and the first electrodes TX1 and the third electrodes RX1 are disposed on the same layer and are formed by patterning at one time, so that a process flow may be simplified.

Step S13: a dielectric layer 2 is formed on the plurality of first electrodes TX1 and the plurality of third electrodes RX 1. Referring to fig. 5, fig. 5 is a schematic diagram illustrating another structure of the fingerprint recognition module according to the embodiment of the present invention in the manufacturing process, the dielectric layer 2 covers the first electrode TX1 and the third electrode RX1, the dielectric layer 2 may be made of negative photoresist and coated on the surfaces of the first electrode TX1, the third electrode RX1 and the flat layer, and the negative photoresist material may include an organic material such as polystyrene (PS for short).

Fig. 6 is a top view of the fingerprint recognition module corresponding to fig. 5 in the manufacturing process. Referring to fig. 6, after the negative photoresist is coated to form a film, the negative photoresist is exposed, and the region of the dielectric layer 2 except for the region where the cavity is to be formed, the region other than the etching hole C2 and the etching runner C3 required for etching the cavity and the via hole for connecting the third electrode RX1 and the fourth electrode RX2, is an exposed region, and the region where the cavity is to be formed includes the region C11 where the first cavity 31 is to be formed and the region C12 where the second cavity 41 is to be formed. For example, etching holes and etching runners can be reserved on two sides of the area where the cavity is to be formed, which is beneficial to improving etching efficiency.

Step S14: a plurality of diaphragms 32 and a plurality of fourth electrodes RX2 are formed on the dielectric layer 2. Referring to fig. 7, fig. 7 is a schematic diagram illustrating another structure of the fingerprint recognition module according to the embodiment of the present invention in the manufacturing process, in which the diaphragm 32 and the fourth electrode RX2 are formed in two steps, an inorganic material such as silicon nitride (SiNx) or silicon oxide (SiOx) may be deposited on the dielectric layer 2, and then patterned to form a plurality of diaphragms 32, the diaphragms 32 cover the first area in fig. 6, a conductive material is deposited on the dielectric layer 2, and then patterned to form a plurality of fourth electrodes RX2, and the fourth electrodes RX2 cover the second area in fig. 6.

Step S15: the etching medium layer 2 forms a plurality of first cavities 31 and a plurality of second cavities 41. Referring to fig. 8, fig. 8 is a schematic diagram of another structure of the fingerprint identification module in the manufacturing process according to the embodiment of the present invention, the above-mentioned unexposed area is developed through etching holes and etching runners, so that a first cavity 31, a second cavity 41 and a via hole for connecting the third electrode RX1 and the fourth electrode RX2 can be formed, and the negative photoresist remaining after development is the dielectric portion 21 of the dielectric layer 2, where the depth of the via hole is the same as the depth of the first cavity 31 and the second cavity 41, so that the via hole can expose a partial area of the third electrode RX1 at the corresponding position. The cross-sectional shapes of the first cavity 31 and the second cavity 41 may be circular, rectangular or other shapes, and the apertures of the first cavity 31 and the second cavity 41 may be the same or different, and need to be determined according to the ultrasonic frequency when the ultrasonic transmitting device T and the ultrasonic receiving device R are operated, and the shape and the size of the first cavity 31 and the second cavity 41 are not limited in this embodiment of the present invention.

The first cavities 31 and the diaphragms 32 are in one-to-one correspondence, the orthographic projection of the diaphragms 32 on the driving substrate 1 covers the orthographic projection of the first cavities 31 on the driving substrate 1, the second cavities 41 and the fourth electrodes RX2 are in one-to-one correspondence, the orthographic projection of the fourth electrodes RX2 on the driving substrate 1 covers the orthographic projection of the second cavities 41 on the driving substrate 1, and each diaphragm 32 and each fourth electrode RX2 are overlapped on the adjacent medium part 21 in a partial area, so that the medium part 21 can support the diaphragms 32 and the fourth electrodes RX2, and the risk that the diaphragms 32 and the fourth electrodes RX2 collapse in the corresponding cavities is reduced. Subsequently, an electrode connection portion 43 may be formed in the via hole of the dielectric portion 21 by depositing and patterning a conductive material, and the electrode connection portion 43 penetrates through the dielectric portion 21 for connecting the fourth electrode RX2 and the third electrode RX1, and the conductive material used for the electrode connection portion 43 may be the same as or different from the conductive material used for the third electrode RX1 and the fourth electrode RX 2.

Step S16: a piezoelectric layer 42 is formed on the fourth electrode RX 2. Referring to fig. 9, fig. 9 is a schematic diagram illustrating another structure of a fingerprint recognition module in the manufacturing process according to an embodiment of the present invention, a piezoelectric material is coated on a fourth electrode RX2, and patterned and polarized to form a plurality of piezoelectric layers 42, where the piezoelectric material may include, but is not limited to, piezoelectric ceramics, aluminum nitride (AlN), zinc oxide (ZnO), polyvinylidene fluoride (polyvinylidene difluoride, PVDF for short), and the like.

Step S17: a second electrode TX2 is formed on the diaphragm 32 and a fifth electrode RX3 is formed on the piezoelectric layer 42. Referring to fig. 10, fig. 10 is a schematic diagram illustrating another structure of the fingerprint recognition module according to the embodiment of the present invention in the manufacturing process, in which a conductive material is deposited on the diaphragm 32 and patterned to form each second electrode TX2, and the first electrode TX1, the first cavity 31, the diaphragm 32 and the second electrode TX2 form the ultrasonic emission device T. Each of the fifth electrodes RX3 may be formed by depositing a conductive material on the piezoelectric layer 42 and patterning it, and the third electrode RX1, the fourth electrode RX2, the piezoelectric layer 42, and the fifth electrode RX3 constitute the ultrasonic wave receiving device R. The second electrode TX2 and the fifth electrode RX3 may be formed by a one-time patterning process or may be formed by a two-time patterning process.

Step S18: the encapsulation layer 5 is formed on the ultrasonic wave transmitting device T and the ultrasonic wave receiving device R. After step S18 is completed, a fingerprint recognition module as shown in fig. 2 may be formed, and an insulating material is coated on the surfaces of the ultrasonic transmitting device T and the ultrasonic receiving device R to form a packaging layer 5, where the packaging layer 5 can isolate water and oxygen and foreign matters, so as to avoid adverse effects on device performance.

Fig. 11 is a cross-sectional view of a fingerprint recognition module according to another embodiment of the present invention.

Fig. 11 shows a further cross-section of the AA' section of fig. 1. As shown in fig. 11, the fingerprint recognition module provided in the embodiment of the present invention is different from the fingerprint recognition module in the previous embodiment in that the structure of the ultrasonic receiver R is different. In the embodiment of the present invention, the ultrasonic receiving device R includes: the piezoelectric device comprises a third electrode RX1, a piezoelectric layer 42 and a fourth electrode RX2, wherein the piezoelectric layer 42 is positioned on one side of the third electrode RX1, which is away from the driving substrate 1, and the fourth electrode RX2 is positioned on one side of the piezoelectric layer 42, which is away from the third electrode RX1, and the third electrode RX1 and the fourth electrode RX2 are respectively connected to the driving circuit 12.

In the embodiment of the present invention, the piezoelectric layer 42 may be made of a piezoelectric material with a relatively large piezoelectric coefficient, for example, polyvinylidene fluoride (PVDF), where PVDF has a relatively large piezoelectric coefficient and has a relatively good capability of converting mechanical deformation into an electrical signal, so that the ultrasonic receiving device R may have a relatively good sensitivity, which is beneficial to improving the speed of fingerprint identification and imaging definition.

Based on the same inventive concept, the implementation of the present invention also provides a method for manufacturing a fingerprint identification module, where the method for manufacturing a fingerprint identification module includes the step S11 and the step S12, which are not described herein, and the method for manufacturing a fingerprint identification module further includes the following steps S23 to S28, specifically as follows:

Step S23: a piezoelectric layer 42 is formed on the third electrode RX 1. Referring to fig. 12, fig. 12 is a schematic diagram illustrating another structure of the fingerprint recognition module according to the embodiment of the present invention in the manufacturing process, a piezoelectric material such as PVDF is coated on the third electrode RX1, and patterned and polarized to form the piezoelectric layer 42.

Step S24: a dielectric layer 2 is formed on the plurality of first electrodes TX1 and the driving substrate 1. Referring to fig. 13, an exemplary embodiment of a fingerprint recognition module according to the present invention is shown in fig. 13, in which the dielectric layer 2 includes a plurality of hollow portions 22, the piezoelectric layer 42 is located in the hollow portions 22, and a surface of a side of the piezoelectric layer 42 facing away from the driving substrate 1 may be flush with a surface of a side of the dielectric layer 2 facing away from the driving substrate 1. The dielectric layer 2 may employ a negative photoresist and be coated on the surface of the first electrode TX1 and the planarization layer, and the negative photoresist material may include an organic material such as PS, for example.

Fig. 14 is a top view of the fingerprint recognition module of fig. 13 during the manufacturing process. Referring to fig. 14, after the negative photoresist is coated to form a film, the negative photoresist is exposed, and the regions of the dielectric layer 2 other than the region C11 where the first cavity is to be provided, the etching holes C2 and the etching runners C3 required for etching the cavity, and the piezoelectric layer 42 are exposed regions. For example, the etching holes C2 and the etching channels C3 may be reserved on both sides of the area where the cavity is to be formed, which is beneficial to improving etching efficiency. The cross-sectional shape of the piezoelectric layer 42 may be circular, rectangular, or any other shape, and the size of the piezoelectric layer 42 is determined according to the frequency of the ultrasonic wave to be received, and the shape and size of the piezoelectric layer 42 are not limited in this embodiment of the present invention.

Step S25: a plurality of diaphragms 32 and a plurality of fourth electrodes RX2 are formed on the dielectric layer 2. Referring to fig. 15, fig. 15 is a schematic diagram illustrating another structure of the fingerprint recognition module according to the embodiment of the present invention in the manufacturing process, where the diaphragm 32 and the fourth electrode RX2 are formed in two steps, an inorganic material such as silicon nitride (SiNx) or silicon oxide (SiOx) may be deposited on the dielectric layer 2, and then patterned to form a plurality of diaphragms 32, the diaphragms 32 cover a first area in fig. 14, then a conductive material is deposited on the dielectric layer 2, and then patterned to form a plurality of fourth electrodes RX2, and the fourth electrodes RX2 cover a second area in fig. 14, that is, an area where the piezoelectric layer 42 is located. The plurality of diaphragms 32 and the plurality of first electrodes TX1 are in one-to-one correspondence, and the plurality of fourth electrodes RX2 and the plurality of third electrodes RX1 are in one-to-one correspondence, and the third electrodes RX1, the piezoelectric layer 42 and the fourth electrodes RX2 constitute an ultrasonic receiving device R.

Step S26: the etching medium layer 2 forms a plurality of first cavities 31. Referring to fig. 16, fig. 16 is a schematic diagram illustrating another structure of the fingerprint identification module according to the embodiment of the present invention in the manufacturing process, where the above-mentioned unexposed area is developed through the etching hole and the etching runner, so that a first cavity 31 may be formed, and the negative photoresist remaining after the development is the dielectric portion 21 of the dielectric layer 2.

The cross-sectional shape of the first cavity 31 may be circular, rectangular or other shapes, and the aperture of the first cavity 31 is determined according to the ultrasonic frequency when the ultrasonic transmitting device T and the ultrasonic receiving device R are operated, and the shape and the size of the first cavity 31 are not limited in this embodiment of the present invention.

The first cavities 31 and the diaphragms 32 are in one-to-one correspondence, and orthographic projection of the diaphragms 32 on the driving substrate 1 covers orthographic projection of the first cavities 31 on the driving substrate 1, and partial areas of the diaphragms 32 are overlapped on adjacent medium portions 21, so that the medium portions 21 can support the diaphragms 32, and risk of collapse of the diaphragms 32 in the first cavities 31 is reduced.

Step S27: a second electrode TX2 is formed on the diaphragm 32. Referring to fig. 17, fig. 17 is a schematic diagram illustrating another structure of the fingerprint recognition module according to the embodiment of the present invention in the manufacturing process, in which a conductive material is deposited on the diaphragm 32 and patterned to form each second electrode TX2, and the first electrode TX1, the first cavity 31, the diaphragm 32 and the second electrode TX2 form the ultrasonic emission device T.

Step S28: the encapsulation layer 5 is formed on the ultrasonic wave transmitting device T and the ultrasonic wave receiving device R. After step S28 is completed, a fingerprint recognition module as shown in fig. 11 may be formed, and an insulating material is coated on the surfaces of the ultrasonic transmitting device T and the ultrasonic receiving device R to form the encapsulation layer 5, so as to isolate water oxygen and foreign matters and avoid adverse effects on the device performance.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (13)

1. The utility model provides a fingerprint identification module which characterized in that includes: a driving substrate and a plurality of fingerprint recognition units connected to the driving substrate;

The fingerprint identification unit comprises an ultrasonic wave transmitting device and an ultrasonic wave receiving device, wherein the ultrasonic wave transmitting device is used for transmitting ultrasonic waves to a fingerprint, and the ultrasonic wave receiving device is used for receiving the ultrasonic waves transmitted by the ultrasonic wave transmitting device in the same fingerprint identification unit and reflected by the fingerprint;

The ultrasonic transmitting device adopts a capacitive ultrasonic transducer, and the ultrasonic receiving device adopts a piezoelectric ultrasonic transducer.

2. The fingerprint recognition module of claim 1, further comprising a dielectric layer, the dielectric layer comprising a dielectric portion and a plurality of hollowed-out portions; the medium part is used for isolating the ultrasonic transmitting device and the ultrasonic receiving device which are adjacent, and the hollowed-out part is used for arranging the ultrasonic transmitting device and the ultrasonic receiving device.

3. The fingerprint recognition module of claim 2, wherein the ultrasonic wave emitting device comprises: a first electrode, a diaphragm and a second electrode; the vibrating diaphragm is positioned at one side of the first electrode, which is away from the driving substrate, and a first cavity is formed between the vibrating diaphragm and the first electrode; the second electrode is positioned at one side of the vibrating diaphragm, which is away from the first electrode, and is in contact with the vibrating diaphragm;

And the orthographic projection of the vibrating diaphragm on the driving substrate and the orthographic projection of the adjacent medium part on the driving substrate are overlapped.

4. A fingerprint recognition module according to claim 3, wherein the ultrasonic wave receiving means comprises: a third electrode, a piezoelectric layer, and a fourth electrode; the piezoelectric layer is positioned on one side of the third electrode, which is away from the driving substrate, and the fourth electrode is positioned on one side of the piezoelectric layer, which is away from the third electrode.

5. A fingerprint recognition module according to claim 3, wherein the ultrasonic wave receiving means comprises: a third electrode, a fourth electrode, a piezoelectric layer, and a fifth electrode; the fourth electrode is positioned at one side of the third electrode, which is away from the driving substrate, a second cavity is formed between the third electrode and the fourth electrode, the third electrode is connected with the fourth electrode, the piezoelectric layer is positioned at one side of the fourth electrode, which is away from the second cavity, and the fifth electrode is positioned at one side of the piezoelectric layer, which is away from the fourth electrode;

and the orthographic projection of the fourth electrode on the driving substrate and the orthographic projection of the adjacent medium part on the driving substrate are overlapped.

6. The fingerprint recognition module of claim 5, wherein the dielectric layer further comprises a plurality of vias extending through the dielectric portion;

The ultrasonic receiving device further comprises an electrode connecting portion, wherein the electrode connecting portion is located in a through hole of the medium portion adjacent to the second cavity, and the electrode connecting portion is used for connecting the third electrode and the fourth electrode.

7. The fingerprint recognition module of any one of claims 4-6, wherein each of the diaphragms and each of the fourth electrodes are disposed in the same layer.

8. The fingerprint recognition module of claim 7, wherein each of the first electrodes is disposed on the same layer as each of the third electrodes.

9. The fingerprint recognition module of any one of claims 1-6, wherein the dielectric layer is a negative photoresist, and the material of the negative photoresist comprises polystyrene.

10. The fingerprint recognition module of any one of claims 1-6, wherein the piezoelectric layer is made of a material including one or more of piezoelectric ceramic, aluminum nitride, zinc oxide, polyvinylidene fluoride.

11. The manufacturing method of the fingerprint identification module is characterized by comprising the following steps:

providing a driving substrate;

Forming a plurality of fingerprint recognition units on the driving substrate; the fingerprint identification unit comprises an ultrasonic transmitting device and an ultrasonic receiving device, wherein the ultrasonic transmitting device adopts a capacitive ultrasonic transducer, and the ultrasonic receiving device adopts a piezoelectric ultrasonic transducer.

12. The method of manufacturing of claim 11, wherein forming a plurality of fingerprint recognition units on the driving substrate comprises:

Forming a plurality of first electrodes and a plurality of third electrodes on the driving substrate;

Forming a dielectric layer on the first electrodes and the third electrodes;

Forming a plurality of vibrating diaphragms and a plurality of fourth electrodes on the dielectric layer; the fourth electrodes are connected with the third electrodes in a one-to-one correspondence manner;

Etching the dielectric layer to form a plurality of first cavities and a plurality of second cavities; the plurality of first cavities are in one-to-one correspondence with the plurality of diaphragms, and orthographic projection of the diaphragms on the driving substrate covers orthographic projection of the first cavities on the driving substrate; the second cavities are in one-to-one correspondence with the fourth electrodes, and orthographic projection of the fourth electrodes on the driving substrate covers orthographic projection of the second cavities on the driving substrate;

Forming a piezoelectric layer on the fourth electrode;

Forming a second electrode on the diaphragm and a fifth electrode on the piezoelectric layer; the ultrasonic wave emitting device comprises the first electrode, the first cavity, the vibrating diaphragm and the second electrode; the ultrasonic wave receiving device comprises the third electrode, the fourth electrode, the piezoelectric layer and the fifth electrode, and the fourth electrode is connected with the third electrode.

13. The method of manufacturing of claim 11, wherein forming a plurality of fingerprint recognition units on the driving substrate comprises:

forming a plurality of first electrodes and a plurality of third electrodes on a driving substrate;

forming a piezoelectric layer on the third electrode;

Forming a dielectric layer on the plurality of first electrodes and the driving substrate; the dielectric layer comprises a plurality of hollowed-out parts, and the piezoelectric layer is positioned in the hollowed-out parts;

Forming a plurality of vibrating diaphragms and a plurality of fourth electrodes on the dielectric layer; the plurality of vibrating diaphragms are in one-to-one correspondence with the plurality of first electrodes, and the plurality of fourth electrodes are in one-to-one correspondence with the plurality of third electrodes; the ultrasonic wave receiving device comprises the third electrode, the piezoelectric layer and the fourth electrode;

Etching the dielectric layer to form a plurality of first cavities; the plurality of first cavities are in one-to-one correspondence with the plurality of diaphragms, and orthographic projection of the diaphragms on the driving substrate covers orthographic projection of the first cavities on the driving substrate;

Forming a second electrode on the diaphragm; the ultrasonic wave emitting device includes the first electrode, the first cavity, the diaphragm, and the second electrode.