# US 2022/0036031 A1 · Optical fingerprint sensor, preparation method thereof, and display device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2022/0036031 A1
- Document ID: US20220036031A1
- Status: Published application
- Kind: A1
- Application number: 17/218,481
- Filed: 2021-03-31
- Published: 2022-02-03
- Earliest claimed: 2020-07-28
- Assignees: Beihai Hkc Optoelectronics Technology Co., Ltd.; Hkc Corporation Limited
- Applicants: Beihai Hkc Optoelectronics Technology Co., Ltd.; Hkc Corporation Limited
- Inventors: En-tsung CHO; Fengyun YANG; Je-hao HSU; Haijiang YUAN
- Web page: https://patentgrep.com/patent/US20220036031A1

## CPC

- G06V 40/1318: {using electro-optical elements or layers, e.g. electroluminescent sensing}
- G02F 1/13338: {Input devices, e.g. touch panels}
- G06V 40/1324: {by using geometrical optics, e.g. using prisms (G06V40/1312 takes precedence)}
- H10F 39/014: {of CMOS image sensors}
- H10F 39/024: {of coatings or optical elements}
- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H10F 39/198: {Contact-type image sensors [CIS]}
- H10F 39/8057: {Optical shielding}
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

Disclosed are an optical fingerprint sensor, a preparation method thereof and a display device. The optical fingerprint sensor includes: a substrate; and a sensor unit, disposed on the substrate and including a thin film transistor and a photosensor electrically connected to the thin film transistor, where the thin film transistor includes a source electrode, a drain electrode, a semiconductor layer, and a light shield layer formed over a channel region between the source electrode and the drain electrode and shielding the semiconductor layer exposed in the channel region.

## Claims

### Claim 1

An optical fingerprint sensor, comprising:
a substrate; and
a sensor unit, disposed on the substrate and comprising a thin film transistor and a photosensor electrically connected to the thin film transistor, wherein the thin film transistor comprises a source electrode, a drain electrode, a semiconductor layer, and a light shield layer formed over a channel region between the source electrode and the drain electrode and shielding the semiconductor layer exposed in the channel region.

### Claim 2 (depends on 1)

The optical fingerprint sensor of claim 1, wherein a part of the source electrode and/or a part of the drain electrode is shielded by the light shield layer.

### Claim 3 (depends on 1)

The optical fingerprint sensor of claim 1, wherein the light shield layer is made of metal.

### Claim 4 (depends on 3)

The optical fingerprint sensor of claim 3, wherein the light shield layer is prepared by a physical vapor deposition method.

### Claim 5 (depends on 3)

The optical fingerprint sensor of claim 3, further comprising an insulation layer between the light shield layer and the semiconductor layer.

### Claim 6 (depends on 1)

The optical fingerprint sensor of claim 1, wherein the photosensor comprises a lower electrode, a gate insulation layer, an electrode layer, a dielectric layer and a transparent conductive layer sequentially stacked on the substrate, wherein the transparent conductive layer is electrically connected to the lower electrode, and the electrode layer is electrically connected to the source electrode or the drain electrode of the thin film transistor.

### Claim 7 (depends on 6)

The optical fingerprint sensor of claim 6, wherein a part of the source electrode or a part of the drain electrode of the thin film transistor is extended above the lower electrode of the photosensor to be configured as the electrode layer of the photosensor.

### Claim 8 (depends on 6)

The optical fingerprint sensor of claim 6, wherein a material of the transparent conductive layer comprises indium tin oxide.

### Claim 9 (depends on 6)

The optical fingerprint sensor of claim 6, wherein a material of the dielectric layer comprises nitrogen-doped amorphous silicon.

### Claim 10 (depends on 1)

The optical fingerprint sensor of claim 1, wherein a material of the substrate comprises glass.

### Claim 11 (depends on 10)

The optical fingerprint sensor of claim 10, wherein a thickness of the substrate is not greater than 1 mm.

### Claim 12 (depends on 1)

The optical fingerprint sensor of claim 1, further comprising an insulation protective layer deposited on the light shield layer.

### Claim 13 (depends on 1)

A preparation method of the optical fingerprint sensor as recited in claim 1, comprising:
providing a substrate;
forming a thin film transistor and a photosensor electrically connected to the thin film transistor on the substrate; and
forming a patterned light shield layer, wherein a channel region between a source electrode and a drain electrode of the thin film transistor is shielded by the light shield layer.

### Claim 14 (depends on 13)

The preparation method of claim 13, wherein forming a thin film transistor and a photosensor electrically connected to the thin film transistor on the substrate comprises:
forming a patterned first metal layer on the substrate, wherein a part of the first metal layer is configured as a gate electrode of the thin film transistor, and the other part of the first metal layer is configured as a lower electrode of the photosensor;
forming a gate insulation layer and a patterned semiconductor layer sequentially stacked on the gate insulation layer;
forming a second metal layer, and patterning the second metal layer to obtain the source electrode and the drain electrode, wherein the source electrode or the drain electrode is extended above the lower electrode to be configured as an electrode layer of the photosensor; and
forming a patterned dielectric layer and a patterned transparent conductive layer sequentially stacked on the electrode layer, wherein the transparent conductive layer is covered on dielectric layer and connected to the lower electrode, the thin film transistor comprises the gate electrode, the gate insulation layer, the semiconductor layer, the source electrode, and the drain electrode, and the photosensor comprises the lower electrode, the gate insulation layer, the electrode layer, and the dielectric layer and the transparent conductive layer.

### Claim 15 (depends on 1)

A display device, comprising a display panel and the optical fingerprint sensor as recited in claim 1 arranged under the display panel.

### Claim 16 (depends on 15)

The display device of claim 15, wherein a substrate of the display panel is made of at least one of glass, polyimide and polyethylene naphthalate.