Thin Film Transistor Aperture Oxygen Supply
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Solution Overview
Problem
Oxide semiconductor-based thin film transistors (TFTs) face challenges in maintaining optimal characteristics due to oxygen deficiency and lattice defects, leading to increased leakage current and low resistance, which are not effectively restored by conventional high-temperature oxygen annealing processes, especially in varying TFT shapes and sizes.
Innovation Solution
The design incorporates a thin film transistor structure with a gate electrode, gate insulating film, oxide semiconductor layer, and channel protective layer, where the source and drain electrodes have apertures, grooves, or protrusions to expose the oxide semiconductor layer, allowing for efficient oxygen supply during high-temperature annealing, thereby restoring transistor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature oxygen annealing is performed to restore oxygen in the oxide semiconductor layer, then oxygen deficiency is improved, but the restoration effectiveness varies with TFT shape and size
Solution Approach 1:
The patent introduces aperture portions in the source and drain electrodes to create localized oxygen supply paths. This allows oxygen to be efficiently supplied to the oxide semiconductor layer at critical regions (near the electrodes) regardless of the overall TFT shape or size, making the restoration process effective across different device geometries
2Reliability
If aperture portions are added to source and drain electrodes to improve oxygen supply, then oxygen deficiency is improved, but device structure becomes more complex
Solution Approach 1:
The source and drain electrodes are segmented by introducing aperture portions (openings) within them. This segmentation creates multiple localized oxygen supply paths through the electrodes, improving oxygen diffusion to the oxide semiconductor layer while maintaining the overall electrode functionality
3Object-generated harmful factors
If oxygen is supplied to restore oxide semiconductor characteristics, then leakage current is reduced, but manufacturing process becomes more complex
Solution Approach 1:
The aperture portions are formed in the source and drain electrodes during the electrode fabrication process itself, before the oxygen annealing step. This preliminary structuring of oxygen supply paths ensures that subsequent oxygen annealing is highly effective without requiring additional complex process steps
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
This approach enables the suppression of leakage current and enhancement of transistor performance, enabling high-luminance light display by ensuring adequate oxygen supply to the oxide semiconductor layer, regardless of TFT shape or size.
Implementation Method 1
it has been known that oxygen annealing is performed under high temperature after a TFT is formed and thereby oxygen is supplied to an absent portion in which oxygen is lacked or oxygen is detached in the oxide semiconductor layer
Implementation Method 2
oxygen is supplied to an absent portion in which oxygen is lacked or oxygen is detached in the oxide semiconductor layer to restore the characteristics
Data Source
AI summary
A thin film transistor with which oxygen is easily supplied to an oxide semiconductor layer and favorable transistor characteristics are able to be restored and a display unit including the same. The thin film transistor includes, sequentially over a substrate, a gate electrode, a gate insulting film, an oxide semiconductor layer including a channel region, and a channel protective layer covering the channel region A source electrode and a drain electrode are formed on the oxide semiconductor layer located on both sides of the channel protective layer, and at least one of the source electrode and the drain electrode has an aperture to expose the oxide semiconductor layer.