Gate Electrode Laminate Structure for Hydrogen Barrier in Thin-Film Transistors
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Solution Overview
Problem
Thin-film transistors using oxide semiconductor layers are unstable due to hydrogen permeation, which causes oxygen deficiency and affects the reliability of display devices, especially when annealed at high temperatures in environments with hydrogen and moisture.
Innovation Solution
Incorporating a laminate structure in the gate electrode and light-shielding layer with a silicon and titanium silicide region, which reduces hydrogen permeation and enhances thermal stability by storing hydrogen, thereby maintaining the properties of the thin-film transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxide semiconductor layers are used in thin-film transistors, then lower power consumption and easier manufacturing are achieved, but hydrogen permeation causes oxygen deficiency and instability
Solution Approach 1:
A hydrogen barrier layer is introduced as an intermediary between the oxide semiconductor layer and the gate electrode. This barrier layer specifically blocks hydrogen permeation while allowing the transistor to maintain its low-power consumption characteristics and manufacturing simplicity. The barrier layer acts as a mediator that prevents harmful hydrogen from reaching the semiconductor layer, thereby resolving the stability issue without sacrificing the ease of manufacture.
Solution Approach 2:
The gate electrode is constructed as a composite structure with multiple layers including a hydrogen barrier layer, a gate electrode layer, and optionally a light shielding layer. This composite structure combines materials with different functions: the barrier layer prevents hydrogen permeation, the gate electrode layer provides electrical functionality, and the light shielding layer blocks light. This composite approach solves the stability problem while maintaining the advantages of oxide semiconductor transistors.
2Manufacturing precision
If high temperature annealing is performed to improve transistor properties, then better performance is achieved, but hydrogen and moisture permeation increases causing instability
Solution Approach 1:
The hydrogen barrier layer serves as a protective intermediary that allows high temperature annealing to be performed for improving transistor properties while preventing hydrogen and moisture from permeating into the oxide semiconductor layer. This enables the manufacturing process to achieve better transistor characteristics without introducing harmful factors during the annealing step.
Solution Approach 2:
The hydrogen barrier layer is positioned beforehand between the oxide semiconductor layer and the gate electrode structure, providing prior protection against hydrogen permeation during subsequent high temperature annealing processes. This preventive measure ensures that even when annealing is performed to improve transistor properties, the semiconductor layer remains protected from hydrogen contamination.
3Device complexity
If gate electrode structure is simplified, then manufacturing complexity is reduced, but hydrogen permeation control is insufficient
Solution Approach 1:
The gate electrode is designed as a composite structure comprising a hydrogen barrier layer, a gate electrode layer, and optionally a light shielding layer. This composite structure adds hydrogen permeation resistance functionality without significantly complicating the manufacturing process. Each layer serves a specific function, and the overall structure can be formed using standard thin-film deposition techniques, maintaining manufacturing simplicity while improving reliability.
Solution Approach 2:
The gate electrode structure is designed to perform multiple functions simultaneously: the hydrogen barrier layer prevents hydrogen permeation, the gate electrode layer provides electrical gating functionality, and the light shielding layer (when present) blocks light. This multi-functional design achieves improved hydrogen resistance without proportionally increasing device complexity, as the additional layers can be integrated into the existing manufacturing flow.
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 laminate structure effectively reduces hydrogen reaching the semiconductor layer, minimizing property variations and improving the reliability and thermal stability of the display device.
Implementation Method 1
a silicide region silicified in vicinity of at least a boundary between the layers is formed. The silicide region stores hydrogen and thereby reduces hydrogen permeation
Implementation Method 2
Incorporating a laminate structure in the gate electrode and light-shielding layer with a silicon and titanium silicide region, which reduces hydrogen permeation
Data Source
AI summary
According to one embodiment, a display device includes a thin-film transistor. The thin-film transistor includes a gate electrode, an insulating layer disposed to superpose the gate electrode, and a semiconductor layer disposed on the insulating layer. The gate electrode is opposed to at least the semiconductor layer in part. The gate electrode includes a laminate including a first layer containing silicon as a main component and a second layer which contains titanium as a main component and which is in contact with the first layer, and is in contact with the insulating layer.