Oxide Semiconductor TFT Buffer Layer Protection
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Solution Overview
Problem
Current thin film transistors face challenges in stability and manufacturing costs, particularly for large-sized display devices, due to issues with current driving efficiency, threshold voltage changes, and high-temperature crystallization processes, which affect the reliability and cost-effectiveness of amorphous and polycrystalline silicon TFTs, and the relatively low stability and mobility of oxide semiconductor TFTs.
Innovation Solution
A display device with a semiconductor layer comprising multiple oxide semiconductor layers, where a first oxide semiconductor layer acts as a physical protection film for the buffer or insulating layer, enhancing structural stability and preventing electrical shorts between the source and drain electrodes by improving the structural stability of the buffer or insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If amorphous silicon is deposited in a short time to form the active layer, then manufacturing time and cost are reduced, but current driving efficiency and stability deteriorate due to low mobility and threshold voltage changes
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to oxide semiconductor, which fundamentally alters the electrical properties to achieve high mobility and stable threshold voltage while maintaining low-temperature processing capability
Solution Approach 2:
The patent uses a composite structure with multiple oxide semiconductor layers (first and second oxide semiconductor layers) with different functions - the first layer provides protection and the second layer provides semiconductor functionality, achieving both stability and performance
2Reliability
If polycrystalline silicon is used to achieve high electron mobility and stability, then current driving efficiency improves, but manufacturing cost increases due to additional crystallization steps and high-temperature processing
Solution Approach 1:
The patent changes the processing temperature parameter from high-temperature crystallization to low-temperature deposition, eliminating the need for additional crystallization steps while achieving comparable or superior electron mobility through oxide semiconductor materials
Solution Approach 2:
The patent replaces the expensive and complex polycrystalline silicon process with a simpler, cheaper oxide semiconductor process that achieves similar performance without requiring high-temperature furnaces or multiple processing steps
3Ease of manufacture
If oxide semiconductor is used to achieve high mobility and low-temperature processing, then manufacturing cost is reduced, but stability deteriorates compared to polycrystalline silicon
Solution Approach 1:
The patent creates a composite structure where the first oxide semiconductor layer serves as a protective buffer layer and the second oxide semiconductor layer serves as the active semiconductor layer, achieving both stability and high mobility
Solution Approach 2:
The first oxide semiconductor layer is deposited beforehand to protect the buffer layer from damage during subsequent processing steps, preventing instability issues that would otherwise occur
4Manufacturing precision
If pixel density is increased to arrange more pixels in a small space, then display resolution improves, but manufacturing process stability becomes more difficult to maintain
Solution Approach 1:
The patent changes the deposition temperature parameter to low-temperature processing, which enables precise control of thin film properties and reduces variability in manufacturing, thereby maintaining process stability even at high pixel densities
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 proposed solution improves the structural stability of the buffer or insulating layer, preventing electrical shorts and enhancing the driving stability of the thin film transistor, thus addressing the limitations of existing TFT technologies.
Implementation Method 1
a first oxide semiconductor layer corresponding to the lower positioned semiconductor layer functions as a physical protection film for damage to a buffer layer or insulating layer
Data Source
AI summary
A display device includes a substrate, a pixel driver on the substrate, and a display element connected to the pixel driver. The pixel driver includes a conductive layer on the substrate, a buffer layer on the conductive layer, a semiconductor layer on the buffer layer, a gate electrode, the gate electrode overlapping the semiconductor layer, and a source electrode and a drain electrode connected to the semiconductor layer. The buffer layer includes a flattened portion overlapping the conductive layer, and a stepped portion overlapping the periphery of the conductive layer. The semiconductor layer includes a first oxide semiconductor layer on the buffer layer, and a second oxide semiconductor layer on the first oxide semiconductor layer. A width of the first oxide semiconductor layer is larger than a width of the second oxide semiconductor layer, and the first oxide semiconductor layer is on the stepped portion of the buffer layer.