Laser Annealing Pulse Shaping for Gradual Display Dehydrogenation
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Solution Overview
Problem
In the manufacturing process of display devices, the annealing process can lead to defects such as film bursting due to hydrogen diffusion from high hydrogen content insulating layers to active layers, which are not effectively dehydrogenated during the dehydrogenation process.
Innovation Solution
A laser annealing method is developed where a pulse shape with specific intensity ratios and durations is used for laser irradiation, setting the intensity ratio of the first peak relative to the third peak between 60% to 70% and the fifth peak relative to the third peak between 50% to 65%, to induce gradual dehydrogenation and improve annealing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional laser annealing process is used, then the annealing speed is high, but hydrogen diffusion from insulating layers causes film bursting defects
Solution Approach 1:
The laser pulse is divided into multiple peaks (first peak, second peak, third peak, etc.) with different intensity ratios. The first peak has an intensity ratio of less than 100% relative to the third peak, creating a segmented temporal structure that enables gradual dehydrogenation followed by effective annealing, preventing film bursting while maintaining high processing speed
Solution Approach 2:
The first peak of the laser pulse performs preliminary dehydrogenation action on the insulating layer before the main annealing action of the third peak. This preliminary removal of hydrogen prevents subsequent film bursting during the high-intensity annealing phase, allowing fast processing without sacrificing film quality
2Manufacturing precision
If the laser intensity is increased to improve annealing uniformity, then the annealing uniformity improves, but film bursting defects occur due to rapid heating
Solution Approach 1:
The laser pulse employs periodic action with multiple peaks at different time points. The first peak (with intensity ratio <100% relative to third peak) performs gentle preliminary heating and dehydrogenation, followed by the third peak providing intense annealing. This periodic structure achieves uniform annealing without causing film bursting from rapid heating
3Device complexity
If a single peak laser pulse is used, then the process is simple, but it cannot achieve both dehydrogenation and uniform annealing
Solution Approach 1:
Instead of a simple single-peak pulse, the laser pulse is segmented into multiple peaks (first, second, third, etc.) with specifically controlled intensity ratios. The first peak intensity is set to less than 100% of the third peak intensity, creating a multi-stage process that achieves both dehydrogenation and uniform annealing, with the complexity justified by the significant improvement in manufacturing precision
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 prevents defects like film bursting and enhances the uniformity of the annealing process, improving the quality and durability of the display devices by ensuring sufficient hydrogen release and controlled heat application.
Implementation Method 1
irradiating a laser beam having the pulse shape to a stage
Implementation Method 2
The amorphous silicon may be crystallized through the annealing process
Implementation Method 3
A dehydrogenation process may be performed before an annealing process to reduce the hydrogen content of the active layer
Implementation Method 4
The hydrogen that has not escaped to the outside may diffuse to the active layer
Data Source
AI summary
A laser annealing method includes selecting a reference intensity from a plurality of intensities of a plurality of peaks; where the reference intensity is used to determine a pulse shape of laser irradiation during laser annealing, setting the pulse shape by setting an intensity ratio of a first peak having a smallest peak occurrence time among the plurality of peaks to less than about 100 percent relative to the reference intensity, and irradiating a laser beam having the pulse shape to a stage.