Oxide Semiconductor Thin-Film Transistor With Hydrogen-Blocking Layer
Solution Overview
Problem
The existing thin-film transistors, particularly oxide semiconductor thin-film transistors, face challenges in maintaining reliability due to hydrogen permeation from plastic substrates, which damages the oxide semiconductor layer and affects the device's performance, especially when used in flexible display applications.
Innovation Solution
A thin-film transistor design incorporating a hydrogen-blocking layer with a multi-layer oxide semiconductor structure, comprising a first sub-layer with higher hydrogen concentration, a second sub-layer with lower carrier concentration and higher resistance, and a third sub-layer as the channel layer, all with specific crystallinity and composition, to prevent hydrogen introduction and ensure stability on plastic substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an oxide semiconductor layer is formed directly on a plastic substrate, then the manufacturing process is simple, but hydrogen permeation from the substrate damages the oxide semiconductor layer and reduces device reliability
Solution Approach 1:
A buffer layer is introduced as an intermediary between the plastic substrate and the oxide semiconductor layer. This buffer layer acts as a mediator that prevents direct contact between hydrogen-containing substrate and the sensitive semiconductor layer, thereby blocking hydrogen permeation while maintaining the overall simplicity of the manufacturing process.
Solution Approach 2:
The structure is segmented into multiple layers: substrate, buffer layer, and oxide semiconductor layer. This segmentation allows the buffer layer to specifically address the hydrogen permeation problem without requiring complete redesign of the entire device structure, thus maintaining ease of manufacture while improving reliability.
2Reliability
If a buffer layer is disposed on the plastic substrate to block hydrogen, then the oxide semiconductor layer is protected from substrate hydrogen, but the buffer layer itself contains hydrogen that can still damage the oxide semiconductor layer
Solution Approach 1:
The oxide semiconductor layer is divided into multiple sub-layers with different compositions and properties. The first sub-layer has higher hydrogen concentration and serves as a hydrogen-blocking layer, while the second sub-layer has lower carrier concentration and higher resistance to provide additional protection. This local differentiation of properties within the layer allows the structure to block hydrogen from the buffer layer while maintaining proper semiconductor function.
3Adaptability or versatility
If the oxide semiconductor layer is used on flexible substrates for flexible displays, then the display can be bent and flexed, but hydrogen discharged from the flexible substrate damages the oxide semiconductor layer
Solution Approach 1:
A buffer layer is introduced as an intermediary between the flexible plastic substrate and the oxide semiconductor layer. This buffer layer acts as a mediator that prevents direct contact between hydrogen-containing substrate and the sensitive semiconductor layer, thereby blocking hydrogen permeation while maintaining the overall simplicity of the manufacturing process.
Solution Approach 2:
The oxide semiconductor layer is divided into multiple sub-layers with different compositions and properties. The first sub-layer has higher hydrogen concentration and serves as a hydrogen-blocking layer, while the second sub-layer has lower carrier concentration and higher resistance to provide additional protection. This local differentiation of properties within the layer allows the structure to block hydrogen from the buffer layer while maintaining proper semiconductor function.
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 solution effectively blocks hydrogen, maintaining the oxide semiconductor layer's integrity and enhancing the reliability and driving properties of the thin-film transistor, even on flexible polyimide substrates, thus enabling the production of reliable flexible display apparatus.
Implementation Method 1
a first sub-layer, a second sub layer and a third sub layer, which are sequentially disposed, wherein the second sub layer has a resistance greater than a resistance of the first sub layer and a resistance of the third sub layer, and a hydrogen concentration of the first sub layer is higher than a hydrogen concentration of the second sub layer and a hydrogen concentration of the third sub layer
Data Source
AI summary
A thin-film transistor is disclosed. The thin-film transistor includes an oxide semiconductor layer disposed on a substrate, a gate electrode disposed so as to overlap at least a portion of the oxide semiconductor layer and isolated from the oxide semiconductor layer, a source electrode connected to the oxide semiconductor layer, and a drain electrode connected to the oxide semiconductor layer and spaced apart from the source electrode, wherein the oxide semiconductor layer includes a first sub layer disposed on the substrate, a second sub layer disposed on the first sub layer, and a third sub layer disposed on the second sub layer, the second sub layer has larger resistance than the first sub layer and the third sub layer and lower carrier concentration than the first sub layer and the third sub layer, the first sub layer has higher hydrogen concentration than the second sub layer and the third sub layer, and each of the first sub layer and the second sub layer has crystallinity.