# US 2022/0035503 A1 · Fingerprint recognition unit and fabrication method thereof, fingerprint recognition module and display device

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- Number: US 2022/0035503 A1
- Document ID: US20220035503A1
- Status: Published application
- Kind: A1
- Application number: 17/242,511
- Filed: 2021-04-28
- Published: 2022-02-03
- Earliest claimed: 2020-07-30
- Assignees: Boe Technology Group Co., Ltd.
- Applicants: BOE Technology Group Co., Ltd.
- Inventors: Wenqu LIU; Qi YAO; Feng ZHANG; Zhao CUI; Libo WANG; Dongfei HOU; Xiaoxin SONG; Zhijun LV; Liwen DONG; Detian MENG; Jaiil RYU; Yang YUE; Haitao HUANG
- Web page: https://patentgrep.com/patent/US20220035503A1

## CPC

- G06F 3/04164: {Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads}
- G06V 40/1306: {non-optical, e.g. ultrasonic or capacitive sensing}
- G06F 3/0412: {Digitisers structurally integrated in a display}
- G06F 3/0443: {using a single layer of sensing electrodes}
- G06F 3/0446: {using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes}
- G06F 3/045: using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
- G06V 40/1329: {Protecting the fingerprint sensor against damage caused by the finger}
- G06F 2203/04103: Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING

## Abstract

The present disclosure provides a fingerprint recognition unit and a fabrication method thereof, a fingerprint recognition module and a display device. The fingerprint recognition unit includes: a bearing substrate; a receiving electrode layer on the bearing substrate; a piezoelectric material layer on a side of the receiving electrode layer away from the bearing substrate; and a driving electrode layer on a side of the piezoelectric material layer away from the receiving electrode layer. A density of the driving electrode layer is greater than 5 g/cm3, and a thickness of the driving electrode layer, a thickness of the piezoelectric material layer and a thickness of the bearing substrate are configured such that a vibration nodal plane of the piezoelectric material layer is within the piezoelectric material layer.

## Claims

### Claim 1

A fingerprint recognition unit, comprising:
a bearing substrate,
a receiving electrode layer on the bearing substrate,
a piezoelectric material layer on a side of the receiving electrode layer away from the bearing substrate; and
a driving electrode layer on a side of the piezoelectric material layer away from the receiving electrode layer;
wherein a density of the driving electrode layer is greater than 5 g/cm3, and a thickness of the driving electrode layer, a thickness of the piezoelectric material layer and a thickness of the bearing substrate are configured such that a vibration nodal plane of the piezoelectric material layer is within the piezoelectric material layer.

### Claim 2 (depends on 1)

The fingerprint recognition unit of claim 1, wherein the receiving electrode layer comprises a plurality of receiving electrodes arranged in an array along a first direction and a second direction intersecting the first direction, and
the driving electrode layer comprises a plurality of driving electrodes arranged along the first direction, each driving electrode is a strip electrode extending along the second direction, and an orthographic projection of each driving electrode on the bearing substrate overlaps orthographic projections of multiple receiving electrodes arranged along the second direction on the bearing substrate.

### Claim 3 (depends on 2)

The fingerprint recognition unit of claim 2, wherein the orthographic projections of the multiple receiving electrodes arranged along the second direction on the bearing substrate are within the orthographic projection of a corresponding driving electrode on the bearing substrate.

### Claim 4 (depends on 1)

The fingerprint recognition unit of claim 1, wherein a material of the driving electrode layer comprises copper.

### Claim 5 (depends on 1)

The fingerprint recognition unit of claim 1, wherein
the thickness of the driving electrode layer is in the range of 14 μm to 45 μm;
the thickness of the piezoelectric material layer is in the range of 8 μm to 10 μm; and
the thickness of the bearing substrate is in the range of 90 μm to 120 μm.

### Claim 6 (depends on 2)

The fingerprint recognition unit of claim 2, wherein the bearing substrate comprises: a base substrate and a fingerprint recognition circuit layer on the base substrate, the receiving electrode layer is on a side of the fingerprint recognition circuit layer away from the base substrate; and
the fingerprint recognition circuit layer comprises a plurality of fingerprint recognition circuits in one-to-one correspondence with the plurality of receiving electrodes, and each fingerprint recognition circuit is electrically connected to a corresponding receiving electrode.

### Claim 7 (depends on 2)

The fingerprint recognition unit of claim 2, further comprising a passivation layer between the receiving electrode layer and the piezoelectric material layer.

### Claim 8 (depends on 1)

The fingerprint recognition unit of claim 1, wherein a material of the piezoelectric material layer comprises: polyvinylidene fluoride.

### Claim 9 (depends on 1)

The fingerprint recognition unit of claim 1, further comprising an encapsulation pattern covering a side surface of the piezoelectric material layer.

### Claim 10 (depends on 9)

The fingerprint recognition unit of claim 9, wherein a side surface of the encapsulation pattern away from the piezoelectric material layer is a slope surface, and an included angle between the slope surface and the side surface of the piezoelectric material layer is in the range of 30 to 60 degrees.

### Claim 11 (depends on 10)

The fingerprint recognition unit of claim 10, further comprising a lead wire arranged along the slope surface, wherein the lead wire is connected to the driving electrode layer.

### Claim 12 (depends on 1)

The fingerprint recognition unit of claim 1, further comprising a protective layer on a side of the driving electrode layer away from the piezoelectric material layer.

### Claim 13 (depends on 12)

The fingerprint recognition unit of claim 12, wherein a material of the protective layer comprises an organic resin material, and a thickness of the protective layer is greater than a thickness of the driving electrode layer.

### Claim 14 (depends on 2)

The fingerprint recognition unit of claim 2, wherein a width of the driving electrode is in the range of 65 μm to 70 μm, an interval between adjacent driving electrodes is in the range of 8 μm to 10 μm; and
the receiving electrode is a rectangular electrode, any side length of the rectangular electrode is in the range of 65 μm to 70 μm, and an interval between adjacent rectangular electrodes is in the range of 8 μm to 10 μm.

### Claim 15 (depends on 1)

A fingerprint recognition module, comprising a plurality of fingerprint recognition units arranged in an array, wherein the fingerprint recognition unit is the fingerprint recognition unit of claim 1.

### Claim 16 (depends on 15)

A display device, comprising: the fingerprint recognition module of claim 15.

### Claim 17

A method of fabricating a fingerprint recognition unit, comprising:
forming a bearing substrate,
forming a receiving electrode layer on the bearing substrate;
forming a piezoelectric material layer on a side of the receiving electrode layer away from the bearing substrate; and
forming a driving electrode layer on a side of the piezoelectric material layer away from the receiving electrode layer, wherein a density of the driving electrode layer is greater than 5 g/cm3, and a thickness of the driving electrode layer, a thickness of the piezoelectric material layer and a thickness of the bearing substrate are configured such that a vibration nodal plane of the piezoelectric material layer is within the piezoelectric material layer.

### Claim 18 (depends on 17)

The method of claim 17, wherein forming the driving electrode layer comprises forming the driving electrode layer having a certain thickness by a metal electroplating process.

### Claim 19 (depends on 18)

The method of claim 18, wherein forming the driving electrode layer having the certain thickness by the metal electroplating process comprises:
forming a copper film as a seed layer on an entire surface of the piezoelectric material layer away from the bearing substrate by an electroplating process, wherein a thickness of the seed layer is in the range of 3000 Å to 5000 Å;
forming a barrier layer on the seed layer, wherein the barrier layer has a hollow structure, and a thickness of the barrier layer is larger than a thickness of a driving electrode to be formed;
forming a copper film in the hollow structure by an electroplating process to form a growth layer pattern;
removing the barrier layer; and
simultaneously thinning the growth layer pattern and the seed layer, so that a portion of the seed layer which is not covered by the growth layer pattern is completely removed, and remaining portion of the growth layer pattern and a portion of the seed layer which is covered by the remaining portion constitute the driving electrode.