Oxide Semiconductor Buffer Layer Contact Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In thin film transistors with an oxide semiconductor used for the channel formation region, there is a challenge of high contact resistance between the oxide semiconductor layer and the source and drain electrodes, leading to signal delay and variation in transistor characteristics, which can cause display unevenness in large-area display devices.
Innovation Solution
The use of an oxide semiconductor layer containing indium, gallium, and zinc, with buffer layers of oxynitride containing indium, gallium, zinc, oxygen, and nitrogen interposed between the oxide semiconductor layer and the source and drain electrodes, to reduce contact resistance and improve conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a low resistance metal material is used for source and drain electrodes to reduce wiring resistance, then electrical conductivity is improved, but contact resistance between the electrode and oxide semiconductor layer increases due to Schottky junction formation
Solution Approach 1:
A buffer layer comprising indium, gallium, zinc, oxygen, and nitrogen is introduced as an intermediary between the low-resistance metal electrode and the oxide semiconductor layer. This buffer layer has a gradient composition that transitions from higher metal content near the electrode to higher oxide content near the semiconductor layer, enabling it to serve as a mediator that reduces contact resistance while allowing the use of low-resistance metal materials for the electrode.
Solution Approach 2:
The buffer layer utilizes parameter changes in composition and structure to resolve the contradiction. By creating a gradient composition where the metal-to-oxide ratio varies through the thickness of the buffer layer, the electrical properties are optimized at each interface: high metal content near the electrode for low contact resistance, and high oxide content near the semiconductor for good interface compatibility, thereby reducing Schottky junction effects.
2Device complexity
If direct contact between oxide semiconductor layer and metal electrode is used to simplify structure, then device complexity is reduced, but contact resistance increases leading to signal delay
Solution Approach 1:
The buffer layer acts as a mediator that enables faster signal transmission by reducing contact resistance at the electrode-semiconductor interface. Although it adds a structural layer, the gradient composition specifically designed for this purpose provides optimal electrical contact, thereby improving signal speed without excessive complexity increase.
Solution Approach 2:
The buffer layer is a composite material containing indium, gallium, zinc, oxygen, and nitrogen in specific proportions. This composite structure combines the benefits of metal conductivity near the electrode with oxide semiconductor compatibility near the channel, achieving low contact resistance and fast signal transmission while maintaining reasonable structural complexity.
3Ease of manufacture
If uniform oxide semiconductor layer is used to simplify manufacturing, then manufacturing precision is maintained, but variation in transistor characteristics increases causing display unevenness
Solution Approach 1:
The buffer layer implements local quality by having different compositions at different locations through its thickness. The region near the electrode has higher metal content for low contact resistance, while the region near the oxide semiconductor has higher oxide content for good interface matching. This local optimization reduces variation in transistor characteristics across the device, improving display uniformity while maintaining ease of manufacture through a single-layer deposition process with gradient composition.
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 results in a thin film transistor with reduced parasitic capacitance and high on/off ratio, enhancing the reliability and stability of the semiconductor device, thereby minimizing display unevenness and improving the operational performance of large-area display devices.
Implementation Method 1
buffer layers comprising indium, gallium, zinc, oxygen, and nitrogen are provided between the oxide semiconductor layer and a source and drain electrodes
Data Source
AI summary
In a thin film transistor which uses an oxide semiconductor, buffer layers containing indium, gallium, zinc, oxygen, and nitrogen are provided between the oxide semiconductor layer and the source and drain electrode layers.