Truncated Laser Spot Beam Crystallization for Uniform Silicon Grains
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Solution Overview
Problem
Existing laser crystallization methods, such as SLS and ELA, are inefficient and costly for producing films with high pixel density required for next-generation devices, as they rely on full melting and solidification cycles and result in non-uniform grain sizes, and are not suitable for high-throughput and low-cost production.
Innovation Solution
The method involves using a truncated laser spot beam with a proximity or projection mask to create a sustained molten zone across a thin film, allowing for uniform polycrystalline structure formation with precise control over energy density, enabling efficient crystallization of thin films with small, uniform grains suitable for high-pixel-density applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If prior laser crystallization methods (SLS and ELA) are used, then complete melting and solidification cycles are achieved, but the grain size uniformity is poor and production efficiency is low
Solution Approach 1:
The laser beam is segmented into multiple discrete spots arranged in a matrix pattern, where each spot creates a localized molten zone. This segmentation allows independent control of crystallization in each zone, improving grain uniformity while enabling parallel processing across the film surface to enhance productivity.
Solution Approach 2:
The laser spots are activated in a sequential periodic pattern across the film, with each spot undergoing complete melting and solidification cycles in a controlled sequence. This periodic action ensures uniform crystallization throughout the film while maintaining high processing speed through automated spot-by-spot progression.
2Reliability
If expensive equipment with high laser maintenance and operating costs is used, then prior crystallization methods can be implemented, but cost-effectiveness deteriorates
Solution Approach 1:
The patent employs a simpler laser system that can be replaced more easily and at lower cost compared to expensive excimer lasers. The spot beam approach uses conventional lasers with shorter lifetimes that are more cost-effective to replace, reducing overall system cost while maintaining crystallization quality through optimized spot processing parameters.
3Speed
If long line-beam is used in ELA and SLS methods, then processing speed is maintained, but grain size uniformity deteriorates for high pixel density applications
Solution Approach 1:
The continuous line beam is segmented into discrete spot locations arranged in a matrix. Each spot is processed individually with controlled dwell time, ensuring uniform energy distribution and consistent grain formation. This segmentation maintains processing speed through automated spot sequencing while achieving the grain uniformity required for high pixel density displays.
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 allows for the production of films with uniform, small-grained structures suitable for high-pixel-density displays, achieved through efficient and cost-effective laser crystallization techniques, utilizing high-frequency lasers with low pulse energy and precise beam shaping to avoid surface melting and ensure uniform crystallization.
Implementation Method 1
irradiating an amorphous silicon area of the thin film to generate a molten zone in the irradiated amorphous silicon area
Implementation Method 2
Both methods rely on one complete cycle of melting-and-solidification before continuing the processing of the film
Implementation Method 3
crystallizes to form uniform polycrystalline structures or grains
Data Source
AI summary
Methods and systems for crystallizing a thin film provide an optics system configured to produce a laser spot beam directed towards the thin film and truncate the laser spot beam before the laser spot beam comes into contact with the thin film. The truncated laser spot beam is continually translated in a first direction while irradiating an amorphous silicon area of the thin film to generate a molten zone in the irradiated amorphous silicon area, where the thin film cools and solidifies to form crystal grains.