# US 2021/0242350 A1 · Thin film transistor, manufacturing method of thin film transistor, and liquid crystal display

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- Number: US 2021/0242350 A1
- Document ID: US20210242350A1
- Status: Published application
- Kind: A1
- Application number: 16/972,621
- Filed: 2019-03-29
- Published: 2021-08-05
- Earliest claimed: 2018-12-21
- Assignees: Wuhan China Star Optoelectronics Technology Co., Ltd.
- Applicants: Wuhan China Star Optoelectronics Technology Co., Ltd.
- Inventors: Mingjuan LI
- Web page: https://patentgrep.com/patent/US20210242350A1

## CPC

- H10D 30/6757: {characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile (TFTs having channel structures for preventing kink or snapback effects H10D30/6708; TFTs having lightly-doped source or drain extensions H10D30/6715)}
- H10D 86/451: {characterised by the compositions or shapes of the interlayer dielectrics}
- G02F 1/1362: Active matrix addressed cells {(G02F1/134336, G02F1/134363 take precedence)}
- G02F 1/1368: in which the switching element is a three-electrode device {(G02F1/136277 takes precedence)}
- H10D 30/031: {of thin-film transistors [TFT]}
- H10D 30/6713: {characterised by the properties of the source or drain regions, e.g. compositions or sectional shapes}
- H10D 86/441: {Interconnections, e.g. scanning lines}
- H10D 86/60: wherein the TFTs are in active matrices
- G02F 2203/02: reflective
- H10D 30/6743: {Silicon}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- 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

## Abstract

The present disclosure provides a thin film transistor, a manufacturing method of the thin film transistor, and a liquid crystal display. The thin film transistor includes a substrate; an active region arranged above the substrate; a channel region arranged in a center of the active region; source and drain regions arranged on two sides of the channel region; a gate dielectric layer arranged above the channel region; a reflective coating arranged above the gate dielectric layer; a gate metal arranged above the reflective coating; an interlayer dielectric layer covering the gate metal, the active region, and the substrate; and a source/drain metal layer passing through the interlayer dielectric layer and electrically connecting with a surface of the source and drain regions.

## Claims

### Claim 1

A thin film transistor, comprising:
a substrate;
an active region arranged above the substrate;
a channel region arranged in a center of the active region;
source and drain regions arranged on two sides of the channel region;
a gate dielectric layer arranged above the channel region;
a reflective coating arranged above the gate dielectric layer;
a gate metal arranged above the reflective coating;
an interlayer dielectric layer covering the gate metal, the active region, and the substrate; and
a source/drain metal layer passing through the interlayer dielectric layer and electrically connecting with a surface of the source and drain regions.

### Claim 2 (depends on 1)

The thin film transistor according to claim 1, wherein a reflectivity of the reflective coating to visible light is greater than or equal to 80%.

### Claim 3 (depends on 2)

The thin film transistor according to claim 2, wherein the reflective coating is a metal with a mirror surface structure.

### Claim 4 (depends on 3)

The thin film transistor according to claim 3, wherein material of the reflective coating is silver or aluminum.

### Claim 5

A manufacturing method of the thin film transistor, comprising the steps:
providing a substrate;
forming an active region on the substrate;
forming a channel region arranged in a center of the active region;
forming source and drain regions arranged on two sides of the channel region;
forming a gate dielectric layer arranged above the channel region;
forming a reflective coating above the gate dielectric layer;
forming a gate metal arranged above the reflective coating;
forming an interlayer dielectric layer that covers the gate metal, the active region, and the substrate; and
forming a source/drain metal layer passes through the interlayer dielectric layer and electrically connecting with a surface of the source and drain regions.

### Claim 6 (depends on 5)

The manufacturing method of the thin film transistor according to claim 5, wherein the step of forming the gate dielectric layer arranged above the channel region further comprises:
forming a sacrificial dielectric layer above the channel region, wherein the sacrificial dielectric layer is made of silicon oxide or silicon nitride, and thickness of the sacrificial dielectric layer is greater than or equal to twice of thickness of the gate dielectric layer; and
polishing the sacrificial dielectric layer by chemical mechanical polishing, wherein a part of the sacrificial dielectric layer is removed, such that thickness of remaining sacrificial dielectric layer is equal to the thickness of the gate dielectric layer for forming the gate dielectric layer;
wherein a surface of the gate dielectric layer is a polished surface.

### Claim 7 (depends on 6)

The manufacturing method of the thin film transistor according to claim 6, wherein a reflectivity of the reflective coating to visible light is greater than or equal to 80%.

### Claim 8 (depends on 7)

The manufacturing method of the thin film transistor according to claim 7, wherein the reflective coating is a metal with a mirror surface structure, and wherein the step of forming the reflective coating above the gate dielectric layer further comprises:
forming the metal with the mirror surface structure on the polished surface by an electroplating method.

### Claim 9 (depends on 8)

The manufacturing method of the thin film transistor according to claim 8, wherein material of the reflective coating is silver or aluminum.

### Claim 10

A liquid crystal display comprising a thin film transistor array, wherein the thin film transistor array comprises a plurality of thin film transistors which are electrically connected with each other, each of the thin film transistors comprising:
a substrate;
an active region arranged above the substrate;
a channel region arranged in a center of the active region;
source and drain regions arranged on two sides of the channel region;
a gate dielectric layer arranged above the channel region;
a reflective coating arranged above the gate dielectric layer;
a gate metal arranged above the reflective coating;
an interlayer dielectric layer covering the gate metal, the active region, and the substrate; and
a source/drain metal layer passing through the interlayer dielectric layer and electrically connecting with a surface of the source and drain regions.

### Claim 11 (depends on 10)

The liquid crystal display according to claim 10, wherein the reflectivity of the reflective coating to visible light is greater than or equal to 80%.

### Claim 12 (depends on 11)

The liquid crystal display according to claim 11, wherein the reflective coating is a metal with a mirror surface structure.

### Claim 13 (depends on 12)

The liquid crystal display according to claim 12, wherein material of the reflective coating is silver or aluminum.