Polycrystalline Silicon TFT Crystallization Uniformity
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Solution Overview
Problem
The use of hydrogenated amorphous silicon (a-Si:H) in thin film transistors (TFTs) for display devices results in low field effect mobility and response speeds, making high-speed driving difficult, and polycrystalline silicon TFTs are needed for improved performance, but they require complex processes and uniformity challenges during laser crystallization.
Innovation Solution
An organic light-emitting display device with TFTs using polycrystalline silicon and a manufacturing method that includes laser crystallization, patterning, and the use of dummy pixels to monitor and correct for crystallization unevenness, allowing for improved detection of defects and enhanced device characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hydrogenated amorphous silicon (a-Si:H) is used in TFTs, then the manufacturing process is simple and low-cost, but the field effect mobility and response speeds are low
Solution Approach 1:
The patent changes the material parameter from hydrogenated amorphous silicon to polycrystalline silicon, which fundamentally alters the electrical properties (field effect mobility) while maintaining compatibility with existing manufacturing processes through laser crystallization technology
Solution Approach 2:
The patent utilizes laser crystallization to transform amorphous silicon into polycrystalline silicon through controlled phase transition, achieving high mobility characteristics while using a established manufacturing approach
2Reliability
If polycrystalline silicon is used in TFTs, then field effect mobility and response speeds improve, but the manufacturing process becomes complex with uniformity challenges
Solution Approach 1:
The patent forms a complete amorphous silicon layer across the entire substrate before laser crystallization, ensuring uniform starting conditions that simplify the subsequent crystallization process and improve manufacturing consistency
Solution Approach 2:
The patent implements test patterns and dummy pixels that provide feedback on crystallization quality, allowing for process optimization and defect detection that reduces manufacturing complexity
3Reliability
If laser crystallization is used to form polycrystalline silicon, then field effect mobility improves, but unevenness and defects in crystallization occur
Solution Approach 1:
The patent forms a uniform amorphous silicon layer as a preliminary step before laser crystallization, ensuring consistent material properties across the substrate that lead to more uniform crystallization results
Solution Approach 2:
The patent uses dummy pixels as copies of actual pixels to monitor and detect crystallization unevenness, allowing for quality control without affecting the functional pixels
4Measurement precision
If dummy pixels are added to monitor crystallization, then detection of defects improves, but device structure becomes more complex
Solution Approach 1:
The patent designs dummy pixels with the same structure as functional pixels, allowing them to serve dual purposes: monitoring crystallization quality and potentially serving as backup functional pixels, thereby reducing overall device complexity
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 enables high-speed and stable operation of display devices with improved field effect mobility and response times, while simplifying the manufacturing process by using dummy pixels to monitor and correct for crystallization unevenness, ensuring high-quality device production.
Implementation Method 1
an active layer that is formed by patterning a semiconductor layer formed by laser crystallization
Data Source
AI summary
An organic light-emitting display device and a method of manufacturing the same. The organic light-emitting display device includes: an active layer that is formed by patterning a semiconductor layer formed by laser crystallization; a gate electrode that is disposed to correspond to a channel area of the active layer; a first insulating layer that is disposed between the active layer and the gate electrode; a second insulating layer that is disposed on the gate electrode; and first test patterns that are formed on the second insulating layer and contact source and drain regions of the active layer and the gate electrode, respectively.