Excimer-Laser Annealed TFT Structure for Higher Mobility
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Solution Overview
Problem
Conventional amorphous silicon thin film transistors (TFTs) have low mobility, leading to slow charging and discharging speeds in display panels, affecting response time and overall performance.
Innovation Solution
Incorporating an annealed microcrystalline or polycrystalline silicon layer formed by excimer laser annealing, combined with an n+-type hydrogenated amorphous silicon layer to enhance carrier mobility and form a super amorphous silicon structure, along with optimized energy density for excimer laser annealing to achieve high mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional amorphous silicon material is used for the active layer, then the manufacturing process is simple, but the mobility is low (0.2-0.5 cm2/V*S) resulting in slow charging and discharging speed
Solution Approach 1:
The patent applies excimer laser annealing to transform the crystalline structure of amorphous silicon, changing its physical parameters to achieve microcrystalline or polycrystalline states. This parameter change increases carrier mobility from 0.2-0.5 cm2/V*S to above 10 cm2/V*S while maintaining the amorphous silicon material system, thus resolving the contradiction between manufacturing simplicity and mobility performance
Solution Approach 2:
The patent creates a composite structure by forming an annealed microcrystalline silicon layer combined with an n+-type hydrogenated amorphous silicon layer. This composite structure leverages the high mobility of microcrystalline silicon and the good interface properties of hydrogenated amorphous silicon to achieve superior overall performance, resolving the mobility limitation of conventional amorphous silicon
2Manufacturing precision
If the mobility is increased by using microcrystalline or polycrystalline silicon, then the charging and discharging speed improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent replaces conventional thermal annealing or solid-phase crystallization methods with excimer laser annealing. This substitution uses optical energy (excimer laser) instead of prolonged thermal processing to achieve rapid localized heating and crystallization, significantly reducing process time and complexity while achieving the desired microcrystalline structure and high mobility
Solution Approach 2:
The excimer laser annealing process employs periodic pulsed laser action to achieve controlled heating and cooling cycles. This periodic action enables precise control over the crystallization process, transforming amorphous silicon into microcrystalline structures with high mobility while maintaining process simplicity through repeated short-duration pulses
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 increases TFT mobility by more than ten times, resulting in improved display panel refresh rates and resolution, enhancing the overall display performance.
Implementation Method 1
the annealed layer 51 is made of amorphous silicon material by excimer laser annealing
Data Source
AI summary
The present disclosure provides a TFT. The TFT includes a gate electrode, an insulating layer on the gate electrode, and an active layer on the insulating layer. The active layer includes an annealed layer and an a-Si layer. The annealed layer is between the a-Si layer and the insulating layer. The annealed layer is made of amorphous silicon material by excimer laser annealing. The present disclosure further provides a TFT array substrate and a method of manufacturing a TFT.