Micro Lens Array Crystallization for Thin Film Transistors
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Solution Overview
Problem
The existing crystallization methods for thin film transistors, such as sequential lateral solidification (SLS) and excimer laser annealing (ELA), are time-consuming due to their entire surface scanning approach, limiting the integration of pixel units and driving circuit units on a glass substrate.
Innovation Solution
A method involving a micro lens array for local crystallization of semiconductor layers using laser irradiation, with multiple laser exposures to achieve complete or partial melting, allowing for faster and more uniform crystallization of channel regions in thin film transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If entire surface scanning method (ELA or SLS) is used for crystallization, then complete crystallization coverage is achieved, but process time becomes excessively long
Solution Approach 1:
The patent divides the crystallization process into multiple sequential stages: first crystallizing the channel region, then the source/drain regions, and finally the pixel electrode region. This segmentation allows each region to be crystallized with optimized parameters, achieving uniform crystallization without requiring excessive time for entire surface scanning.
Solution Approach 2:
The patent applies different crystallization conditions to different regions of the substrate. The channel region receives laser irradiation with specific energy density and duration optimized for transistor performance, while other regions receive tailored treatment. This local quality approach ensures each region achieves optimal crystallization characteristics appropriate to its functional requirements.
2Ease of manufacture
If amorphous silicon thin film transistor is used, then manufacturing simplicity is maintained, but electric mobility is insufficient for high-speed peripheral circuits
Solution Approach 1:
The patent utilizes phase transition of silicon from amorphous to crystalline state through controlled laser irradiation. By applying specific energy density and duration, the amorphous silicon layer transforms into crystalline silicon with superior electrical properties including higher carrier mobility, while maintaining the thin-film structure necessary for TFT fabrication.
Solution Approach 2:
The patent changes key parameters of the silicon layer through laser treatment: temperature, crystalline structure, and electrical properties. By controlling laser energy density, irradiation duration, and wavelength, the silicon layer transitions from amorphous to crystalline state, achieving the desired balance between manufacturing ease and high-speed performance.
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 reduces process time and achieves uniform crystallization, enhancing the integration of pixel and driving circuit units on a glass substrate, improving the electric characteristics of thin film transistors by increasing crystal size and reducing offset current.
Implementation Method 1
a portion corresponding to a channel region of a thin film transistor is locally crystallized by using a micro lens array
Implementation Method 2
crystallizing the semiconductor layer... locally irradiated by a laser at least two times
Implementation Method 3
complete melting crystallization or partial melting crystallization
Implementation Method 4
achieves complete or partial melting, allowing for faster and more uniform crystallization
Data Source
AI summary
Exemplary embodiments of the invention disclose a method of manufacturing a thin film transistor array panel having reduced overall processing time and providing a uniform crystallization. Exemplary embodiments of the invention also disclose a crystallization method of a thin film transistor, including forming on a substrate a semiconductor layer including a first pixel area, a second pixel area, and a third pixel area. The crystallization method includes crystallizing a portion of the semiconductor layer corresponding to a channel region of a thin film transistor using a micro lens array.