Double-Layer Oxide Semiconductor TFT for Display Substrates
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Solution Overview
Problem
Oxide semiconductor thin-film transistors (TFTs) in display substrates face issues with electrical safety and reliability due to the deoxidization and extraction of positive ions, leading to decreased charge mobility and increased resistance, primarily because of the reaction between oxide semiconductors and metal electrodes.
Innovation Solution
A display substrate with a double-layer oxide semiconductor structure, where the second semiconductor pattern is indium-free, such as zinc oxide or tin oxide, is used to prevent deoxidization and ion extraction, combined with a gate insulating layer of silicon nitride and silicon oxide, and electrodes made of titanium, copper, and copper-manganese alloys to enhance electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If oxide semiconductor TFT is used to achieve higher charge mobility and low temperature process, then charge mobility is improved and manufacturing cost is reduced, but deoxidization and ion extraction occur causing electrical safety and reliability to deteriorate
Solution Approach 1:
The oxide semiconductor layer is divided into two distinct layers: a first oxide semiconductor layer containing indium oxide and a second oxide semiconductor layer containing indium-free oxide (such as zinc oxide, tin oxide, or gallium zinc oxide). This segmentation prevents deoxidization and ion extraction by isolating the metal-containing layer from direct contact with metal electrodes, while maintaining high charge mobility through the coordinated structure of both layers.
2Device complexity
If single-layer oxide semiconductor structure is used, then manufacturing process is simple, but deoxidization and ion extraction occur leading to decreased charge mobility and increased resistance
Solution Approach 1:
The oxide semiconductor layer is divided into two distinct layers: a first oxide semiconductor layer containing indium oxide and a second oxide semiconductor layer containing indium-free oxide (such as zinc oxide, tin oxide, or gallium zinc oxide). This segmentation prevents deoxidization and ion extraction by isolating the metal-containing layer from direct contact with metal electrodes, while maintaining high charge mobility through the coordinated structure of both layers.
3Ease of manufacture
If oxide semiconductor reacts with metal source or drain electrode, then manufacturing is easy, but positive ion is deoxidized and extracted causing composition change and mobility decrease
Solution Approach 1:
The second oxide semiconductor layer containing indium-free oxide serves as an intermediary barrier between the first oxide semiconductor layer (containing indium oxide) and the metal source/drain electrodes. This intermediary layer prevents direct reaction between the metal electrodes and indium oxide, thereby preventing deoxidization and extraction of positive ions while allowing the manufacturing process to remain simple and cost-effective.
Data Source
AI summary
A display substrate includes a gate line extending in a first direction on a base substrate, a data line on the base substrate and extending in a second direction crossing the first direction, a gate insulating layer on the gate line, a thin-film transistor and a pixel electrode. The thin-film transistor includes a gate electrode electrically connected the gate line, an oxide semiconductor pattern, and source and drain electrodes on the oxide semiconductor pattern and spaced apart from each other. The oxide semiconductor pattern includes a first semiconductor pattern including indium oxide and a second semiconductor pattern including indium-free oxide. The pixel electrode is electrically connected the drain electrode.