Vertical LED Chip Mesa Protection Against Backside Slurry Damage
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Solution Overview
Problem
The conventional vertical LED chip manufacturing process damages the LED chip during backside metallization due to the exposure of light-emitting epitaxial structures and metal layers to polishing slurry, affecting the chip's reliability.
Innovation Solution
A method is introduced where a protective layer is formed on the surface and side walls of the mesas and epitaxial structure, covering the exposed reflective layer, to prevent corrosion during backside metallization, and the epitaxial structure is etched to form mesas with a height difference to reduce internal reflection and improve light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second mesa is formed in the dicing lane region after the first mesa is formed, then the dicing process is facilitated, but the polishing slurry comes into contact with the exposed light-emitting epitaxial structure and metal structure during backside metallization, causing chip damage and reduced reliability
Solution Approach 1:
A protective layer is formed on the first mesa before the second mesa is formed, preventing the polishing slurry from damaging the exposed light-emitting epitaxial structure and metal structure during subsequent backside metallization processes. This preliminary protective action resolves the contradiction by enabling easy dicing while maintaining chip reliability.
2Reliability
If the protective layer is formed on the first mesa before forming the second mesa, then the chip reliability is improved by preventing slurry damage, but the manufacturing process complexity increases
Solution Approach 1:
The protective layer formation process is merged with the existing manufacturing flow by forming it on the first mesa before creating the second mesa. This integration approach maintains chip reliability while avoiding significant increases in manufacturing process complexity, as the protective layer formation is incorporated into the standard process sequence.
3Ease of manufacture
If the exposed light-emitting epitaxial structure and metal structure are left unprotected during backside metallization, then the manufacturing process is simpler, but the LED chip is damaged and reliability is affected
Solution Approach 1:
The protective layer is formed in advance on the first mesa to counteract the harmful effect of polishing slurry during backside metallization. This preliminary anti-action prevents the slurry from damaging the exposed light-emitting epitaxial structure and metal structure, resolving the contradiction between manufacturing simplicity and preventing slurry damage.
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 method enhances the light extraction efficiency, reduces the impact of processing damage on brightness, and improves the chip's reliability without adding new process flows or increasing costs, making it suitable for mass production.
Implementation Method 1
The epitaxial structure is bonded to the front surface of the substrate
Implementation Method 2
The epitaxial structure is etched for a first time at a position corresponding to a dicing region to form a first mesa
Data Source
AI summary
A vertical LED chip structure, a method of manufacturing the same, and a light-emitting device are provided. After an epitaxial structure is bonded to a substrate, the epitaxial structure is etched first to form a first mesa. After the first mesa is formed, the epitaxial structure is continuously etched at the first mesa until the epitaxial structure is etched through and a reflective layer is exposed, and a second mesa is formed. A protective layer is formed on a surface of the structure where the first mesa and the second mesa are formed. The protective layer covers the exposed reflective layer at the second mesa, protects the epitaxial structure and the reflective layer, and protects a side wall of the epitaxial structure and the reflective layer from being corroded by a processing solution after a back surface of the substrate is polished.