Laser Crystallization of Amorphous Silicon Using Surface Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser crystallization methods for transforming amorphous silicon into polycrystalline silicon, such as excimer laser annealing, often result in unevenly spaced grains in the polycrystalline silicon layer, which affects the uniformity and quality of displays like OLEDs and LCDs.
Innovation Solution
A laser crystallization method involving the formation of specific protrusions and depressions on the amorphous silicon layer, with a controlled pitch, followed by irradiation with a laser beam to create a temperature gradient, which guides the formation of uniformly spaced grains in the polycrystalline silicon layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If excimer laser annealing is used to crystallize amorphous silicon into polycrystalline silicon, then the crystallization process is efficient and can be applied in display manufacturing, but the grains in the polycrystalline silicon layer are not evenly spaced
Solution Approach 1:
The patent applies preliminary action by forming protrusions and depressions on the amorphous silicon layer surface before laser irradiation. These pre-formed surface features act as templates that guide the subsequent laser-induced crystallization process, ensuring that grains nucleate and grow at predetermined locations with uniform spacing. The protrusions and depressions are created using nanoimprinting or self-aligned dual-patterning techniques prior to the laser annealing step, thereby preparing the substrate in advance to achieve uniform grain spacing while maintaining high crystallization efficiency.
2Device complexity
If conventional laser crystallization is used, then the process is simple and fast, but the grain uniformity in the polycrystalline silicon layer is poor
Solution Approach 1:
The patent applies segmentation by dividing the amorphous silicon layer surface into distinct regions with protrusions and depressions. This segmentation creates multiple nucleation sites distributed uniformly across the layer, which guides the formation of evenly spaced grains during laser crystallization. The surface is segmented into periodic patterns where protrusions serve as preferential nucleation points, thereby achieving uniform grain distribution without significantly complicating the overall crystallization process.
Solution Approach 2:
The patent applies local quality by creating regions with different surface properties (protrusions and depressions) that have distinct crystallization characteristics. The protrusions, being closer to the laser focal point, receive higher energy density and serve as preferential nucleation sites, while the depressions act as spacing regions. This local differentiation in surface quality ensures that grains form uniformly at specific locations rather than randomly across the entire layer, thereby improving grain uniformity while maintaining process efficiency.
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 method ensures the formation of polycrystalline silicon layers with high grain uniformity, reducing manufacturing costs and time, and enhancing the production capacity of display devices by achieving evenly spaced grains.
Implementation Method 1
irradiating the amorphous silicon layer with a laser beam to form a polycrystalline silicon layer
Implementation Method 2
irradiating the amorphous silicon layer with a laser beam to form a temperature gradient, which guides the formation of uniformly spaced grains
Implementation Method 3
forming a temperature gradient, which guides the formation of uniformly spaced grains in the polycrystalline silicon layer
Data Source
AI summary
A laser crystallization method includes forming a plurality of first protrusions and depressions on a surface of an amorphous silicon layer, wherein a first protrusion and an adjacent first depression of the plurality of first protrusions and depressions, together, have a first pitch, and irradiating the amorphous silicon layer with a laser beam to form a polycrystalline silicon layer.