LED Structure with Mask Layer for Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light emitting diode (LED) devices face challenges such as dislocation and stress due to thermal expansion coefficient differences and the laser lift off process, which affect the reliability and efficiency of the light emitting structure layer.
Innovation Solution
A light emitting device structure is developed with a mask layer and space formation to reduce dislocation and stress, where the nitride semiconductor layer is grown partially on the substrate with a mask layer that does not contact the semiconductor layer, and a conductive support substrate is used to support the light emitting structure layer, reducing damage during the laser lift off process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nitride semiconductor layer is grown on the substrate using conventional methods, then the light emitting structure layer can be formed, but dislocation and stress occur due to thermal expansion coefficient differences
Solution Approach 1:
The patent introduces a mask layer that segments the substrate surface into contact regions and non-contact regions. The nitride semiconductor layer is grown partially on the substrate and partially on the mask layer, creating a segmented growth structure that reduces dislocation propagation and stress accumulation throughout the entire light emitting structure layer.
Solution Approach 2:
The mask layer serves as an intermediary between the substrate and the nitride semiconductor layer. By positioning the mask layer at specific regions, it mediates the thermal expansion coefficient differences and prevents direct stress transmission from the substrate to the light emitting structure layer, thereby reducing dislocation and improving reliability.
2Productivity
If the laser lift off process is used to separate chips, then chip separation can be achieved, but stress and damage occur in the light emitting structure layer
Solution Approach 1:
The patent extracts or removes the mask layer after the nitride semiconductor layer is grown. This extraction creates a controlled separation interface that allows the light emitting structure layer to be released from the substrate with minimal stress and damage during the laser lift off process, thereby maintaining reliability while achieving efficient chip separation.
Solution Approach 2:
The mask layer provides beforehand cushioning during the growth and processing stages. It cushions the light emitting structure layer from substrate-induced stress and facilitates a gentler separation process during laser lift off, reducing damage before the actual chip separation occurs.
3Strength
If the mask layer contacts the nitride semiconductor layer, then structural support is provided, but dislocation and stress increase
Solution Approach 1:
The patent applies local quality by making the mask layer contact the nitride semiconductor layer only at specific peripheral regions rather than across the entire surface. This localized contact provides necessary structural support at the edges while preventing dislocation and stress propagation through the central active regions of the light emitting structure layer.
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 minimizes dislocation and stress in the light emitting structure layer, enhancing the reliability and efficiency of the LED device by improving the growth process and reducing damage during chip separation.
Implementation Method 1
a nitride semiconductor layer is grown on a substrate
Implementation Method 2
a stress of the light emitting structure layer generated in a laser lift off process is reduced
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
Provided are a light emitting device, a method for fabricating the light emitting device, a light emitting device package, and a lighting unit. The light emitting device includes a conductive support substrate, a protection layer on the conductive support substrate, the protection layer having an inclined top surface, a light emitting structure layer including a first conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer between the first conductive type semiconductor layer and the second conductive type semiconductor layer on the conductive support substrate and the protection layer, and an electrode on the light emitting structure layer. A portion of the protection layer is disposed between the conductive support substrate and the light emitting structure layer.