Oxide Semiconductor TFT with Fluorine-Silicon Insulator
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Solution Overview
Problem
Contemporary liquid crystal display devices face challenges in achieving uniform electrical characteristics across wide display devices, with amorphous silicon thin film transistors having low charge mobility and polycrystalline silicon transistors struggling to maintain uniformity.
Innovation Solution
A thin film transistor array substrate is developed with an oxide semiconductor layer, a gate electrode overlapping the oxide semiconductor layer, and insulating films made of fluorine-containing silicon, including a gate insulating film and a passivation film, to enhance charge mobility and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If amorphous silicon thin film transistor is used, then uniform electrical characteristics can be achieved for wide display devices, but charge mobility is low at about 0.5 cm2/Vs
Solution Approach 1:
The patent changes the material parameter of the semiconductor layer from amorphous silicon to oxide semiconductor (such as IGZO - Indium Gallium Zinc Oxide), which fundamentally alters the electrical properties. This material substitution enables charge mobility to increase from 0.5 cm2/Vs to several tens of cm2/Vs while preserving the uniformity characteristics that make amorphous silicon suitable for wide display devices.
Solution Approach 2:
The patent employs composite material structures including multiple insulating films (gate insulating film, passivation film) with different compositions. Specifically, it uses fluorine-containing silicon in the insulating films to prevent hydrogen diffusion into the oxide semiconductor layer, thereby maintaining the high mobility and uniformity of the semiconductor channel.
2Speed
If polycrystalline silicon thin film transistor is used, then charge mobility is high at about a few hundred cm2/Vs, but uniform electrical characteristics cannot be achieved for wide display devices
Solution Approach 1:
The patent changes the crystalline structure parameter of the semiconductor from polycrystalline to amorphous oxide semiconductor. This eliminates grain boundaries that cause variability in polycrystalline silicon, thereby achieving uniform electrical characteristics across wide display devices while maintaining high charge mobility through the oxide semiconductor material's inherent properties.
Solution Approach 2:
The patent applies local quality control by using fluorine-containing silicon specifically in the insulating films that contact the oxide semiconductor layer. This localized material selection prevents hydrogen contamination at the critical interface between insulator and semiconductor, ensuring uniform electrical characteristics without affecting the entire device structure uniformly.
3Ease of manufacture
If conventional insulating films are used with oxide semiconductor layer, then manufacturing is simpler, but electrical characteristics of oxide semiconductor layer deteriorate due to hydrogen diffusion
Solution Approach 1:
The patent introduces fluorine-containing silicon as an intermediary material in the insulating films that contact the oxide semiconductor layer. This intermediary prevents hydrogen diffusion from the insulator into the semiconductor, acting as a barrier that protects the oxide semiconductor's electrical characteristics while allowing the manufacturing process to remain relatively simple.
Solution Approach 2:
The patent uses composite insulating film structures containing fluorine-containing silicon combined with other insulating materials. This composite approach provides both the necessary protection against hydrogen diffusion and the required insulating properties, maintaining manufacturing simplicity while ensuring reliability of the oxide semiconductor layer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of fluorine-containing silicon in the insulating films prevents deterioration of the oxide semiconductor layer's electrical characteristics, achieving higher charge mobility and uniformity, suitable for wide display devices.
Implementation Method 1
At least one of the gate insulating film and the passivation film contains fluorine-containing silicon
Data Source
AI summary
A thin film transistor array substrate, which can have high mobility of charge and can achieve uniform electrical characteristics for wide display devices, and a method of manufacturing the thin film transistor array substrate, are provided. The thin film transistor array substrate includes an oxide semiconductor layer having a channel and formed on an insulating substrate, a gate electrode overlapping the oxide semiconductor layer, a gate insulating film disposed between the oxide semiconductor layer and the gate electrode, and a passivation film formed on the oxide semiconductor layer and the gate electrode. At least one of the gate insulating film and the passivation film contains fluorine-containing silicon.