Laser Lift-Off Irradiation Profile for Crack-Free LED Separation
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Solution Overview
Problem
Existing methods for manufacturing light-emitting devices face challenges in achieving high yield due to delamination defects such as cracks in the semiconductor layer, which occur when the substrate is separated from the semiconductor layer using laser irradiation.
Innovation Solution
A method involving the simultaneous irradiation of a stacked body with laser light, where the irradiation intensity at the central region of the semiconductor layer is greater than at the outer perimeter region, to control the separation timing and reduce delamination defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform laser irradiation is applied to the entire stacked body, then the separation process is simplified, but delamination defects such as cracks occur in the semiconductor layer
Solution Approach 1:
The patent applies different laser irradiation intensities to different regions of the stacked body. Specifically, the center region receives higher irradiation intensity than the peripheral region, creating a localized quality difference in the separation process. This resolves the contradiction by preventing cracks in the semiconductor layer while maintaining a controlled separation process.
Solution Approach 2:
The patent segments the laser irradiation process into two distinct regions: a center region and a peripheral region. By dividing the irradiation area and applying different intensities to each segment, the method prevents uniform stress distribution that causes cracking, thereby improving semiconductor layer integrity while keeping the separation process manageable.
2Productivity
If high laser irradiation intensity is used to ensure complete separation, then separation efficiency improves, but delamination defects increase
Solution Approach 1:
The patent implements local quality control by applying high laser irradiation intensity specifically to the center region where complete separation is needed, while using lower intensity at the periphery where excessive energy causes cracking. This localized approach maintains separation efficiency in critical areas while preventing delamination defects.
Solution Approach 2:
The patent applies partial excessive action by concentrating higher laser energy than necessary in the center region, ensuring complete separation at the most critical area, while using moderate energy at the periphery. This prevents insufficient separation in key areas while avoiding excessive energy that would cause defects elsewhere.
3Reliability
If sequential irradiation of outer perimeter and center regions is used, then delamination defects are reduced, but processing time increases
Solution Approach 1:
The patent merges the irradiation of the outer perimeter region and the center region into a single simultaneous process. By using a laser beam with a non-uniform intensity profile that covers both regions at once, with the center receiving higher intensity, the method achieves the defect-preventing differential irradiation without the time penalty of sequential processing.
Solution Approach 2:
The patent employs periodic action through a single laser pulse that simultaneously delivers appropriate energy doses to both regions. The laser beam's intensity profile is modulated spatially rather than temporally, achieving the effect of differentiated irradiation in one continuous action rather than multiple sequential steps.
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 reduces the timing difference between the separation of the outer perimeter and central regions, thereby minimizing delamination defects and increasing the yield of light-emitting devices.
Implementation Method 1
separating the substrate from the semiconductor layer by irradiating the stacked body with a laser light
Implementation Method 2
separating the substrate from the semiconductor layer by irradiating the stacked body with a laser light
Data Source
AI summary
A method for manufacturing a light-emitting device includes preparing a stacked body including a substrate and a semiconductor layer on the substrate; and separating the substrate from the semiconductor layer by irradiating the stacked body with a laser light. A first region of the stacked body corresponding to an outer perimeter region of the semiconductor layer and a second region of the stacked body corresponding to a center region of the semiconductor layer are simultaneously irradiated with the laser light during the separating. An irradiation intensity of the laser light at the second region of the stacked body is greater than an irradiation intensity of the laser light at the first region of the stacked body.