LED Chip Side Surface Concavo-Convex Structure for Light Extraction
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Solution Overview
Problem
Current methods for increasing light extraction efficiency in light emitting diodes (LEDs) are limited, particularly as they do not effectively utilize concavo-convex patterns on the side surfaces of unit chips, which could enhance light emission.
Innovation Solution
A concavo-convex structure is formed on the side surfaces of LED unit chips during the scribing process using a fluid-jet-guided laser, creating irregular vertical lines that reduce total reflection and enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dry laser is used for scribing the substrate into unit chips, then the side surface of the unit chip is formed smoothly, but the light extraction efficiency remains low due to total reflection
Solution Approach 1:
The patent applies a fluid jet (water) to the scribing process to modify the laser cutting mechanism. The fluid jet guides the laser beam and modifies the interaction between laser and material, transforming the smooth side surface into one with concavo-convex structures. This curvature modification reduces total internal reflection of light at the side surface, thereby improving light extraction efficiency while maintaining manufacturing precision through controlled fluid-jet-guided laser scribing.
2Loss of energy
If concavo-convex patterns are formed on the upper surface of the LED, then the light extraction efficiency is improved, but the side surface remains smooth with no concavo-convex pattern
Solution Approach 1:
The patent makes the scribing process multi-functional by integrating two functions into one step: (1) separating the substrate into unit chips, and (2) forming concavo-convex structures on the side surfaces. By using fluid-jet-guided laser scribing, the same process that creates chip separation also generates the desired surface morphology for light extraction enhancement, eliminating the need for separate surface treatment steps and maintaining process uniformity.
3Ease of manufacture
If the side surface of the unit chip is made smooth, then the manufacturing process is simple, but the light emission is restricted due to total reflection
Solution Approach 1:
The patent introduces a fluid jet (water) as an intermediary medium between the laser beam and the substrate during scribing. This fluid mediator modifies the laser-material interaction, enabling the formation of concavo-convex structures on the side surface that enhance light emission. The fluid jet serves as a bridge that transforms the simple scribing process into one that simultaneously achieves chip separation and light extraction enhancement without complicating the manufacturing流程.
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
The formation of concavo-convex structures on the side surfaces of LED unit chips significantly improves light extraction efficiency by reducing total reflection and allowing for better light emission, with adjustable angles of inclination to control lighting angles.
Implementation Method 1
separating the substrate into unit chips, and at the same time, forming a concavo-convex structure having the shape of irregular vertical lines in a side surface of the unit chip. The separating of the substrate into the unit chips may include scribing the substrate using a fluid-jet-guided laser.
Implementation Method 2
A side surface of the unit chip includes a concavo-convex structure having the shape of irregular vertical lines. The formation of concavo-convex structures on the side surfaces of LED unit chips significantly improves light extraction efficiency by reducing total reflection
Data Source
AI summary
A method of fabricating a light emitting diode (LED) includes: sequentially stacking a first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer on a substrate; and separating the substrate into unit chips, and at the same time, forming a concavo-convex structure having the shape of irregular vertical lines in a side surface of the unit chip.