Laser Annealing Scan Control for Uniform Energy Density
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Solution Overview
Problem
Laser annealing apparatuses face challenges in maintaining uniform energy density distribution across the substrate, leading to non-uniform crystallization of semiconductor thin films, which results in defects like 'streaks' or 'unevenness' in display devices, affecting their yield and quality.
Innovation Solution
The apparatus includes an energy density measuring device and a mirror actuator to adjust the mirror angle, ensuring that the energy density at the ends of the batch radiation area is uniform by measuring and adjusting the energy density at opposite ends during scanning, thereby maintaining consistent energy distribution across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser light is radiated in batch radiation form to multiple processing areas, then productivity is improved by processing multiple areas simultaneously, but energy density uniformity deteriorates causing streaks and unevenness in the processed film
Solution Approach 1:
The patent applies local quality by making the energy density adjustable at different locations within the batch radiation area. Specifically, the energy density at the first end (opposite to the second end) can be independently adjusted to match the energy density at the second end, ensuring uniform crystallization across the entire batch radiation area while maintaining high productivity through simultaneous processing of multiple areas
2Device complexity
If the mirror angle is fixed during scanning, then device complexity is reduced, but energy density uniformity deteriorates causing defects in adjacent scanning areas
Solution Approach 1:
The patent applies dynamics by making the mirror angle adjustable during the scanning process. The mirror angle is changed between scans to compensate for energy density variations at opposite ends of the batch radiation area. This dynamic adjustment ensures that energy density uniformity is maintained across adjacent scanning areas while keeping the control system relatively simple
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 solution reduces the difference in energy density between adjacent scanning areas, minimizing defects and improving the yield and quality of flat panel displays by ensuring uniform crystallization of semiconductor thin films.
Implementation Method 1
laser apparatus configured to output laser light
Implementation Method 2
pulsed ultraviolet laser light absorbed by an upper-layer semiconductor thin film is used to suppress damage to the substrate due to thermal diffusion
Implementation Method 3
an energy density measuring apparatus configured to measure an energy density at, out of a first end and a second end that are opposite ends of the batch radiation area in the second direction, at least the second end
Implementation Method 4
an energy density adjusting apparatus configured to adjust the energy density at least at the first end out of the first end and the second end of the batch radiation area
Data Source
AI summary
Provided is a laser annealing apparatus causing laser light to be radiated to processing receiving areas arranged, out of a first direction and a second direction perpendicular to the first direction, along at least the second direction and move a batch radiation area and a workpiece in the first direction, and the laser annealing apparatus includes an energy density measuring apparatus measuring the energy density at, out of first and second ends of the batch radiation area in the second direction, at least the second end, an energy density adjusting apparatus adjusting the energy density at the first end, and a controller controlling the energy density adjusting apparatus. The energy density at the first end when (N+1)-th scanning is performed is so adjusted that the energy density at the first end in an (N+1)-th scan area approaches the energy density at the second end in the N-th scan area.