LED Chip Insulating Step Structure for Crack Resistance
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Solution Overview
Problem
The existing single-layer silicon oxide insulating layer in LED chips generates significant stress when subsequent structural layers are formed, leading to cracking or whole-layer breaking, which reduces the reliability of the LED chip.
Innovation Solution
An insulating layer comprising a first and second insulating layer with a step structure, where the first insulating layer extends beyond the second insulating layer in a horizontal direction, acting as a buffer to reduce stress and prevent cracking, and can also block water vapor entry to prevent aging failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer thick silicon oxide insulating layer is used, then the insulating performance is improved, but stress concentration occurs leading to cracking or whole-layer breaking of subsequent structural layers
Solution Approach 1:
The single-layer thick silicon oxide insulating layer is divided into two layers: a first insulating layer (300-500 nm thick) and a second insulating layer (500-1000 nm thick). This segmentation distributes the stress more evenly across the insulating structure, preventing stress concentration that would cause cracking or breaking of subsequent structural layers while maintaining the required insulating performance.
2Strength
If the first insulating layer extends beyond the second insulating layer, then stress on subsequent layers is reduced, but the device structure becomes more complex
Solution Approach 1:
The first insulating layer extends beyond the second insulating layer in the horizontal direction, creating a step structure. This dimensional extension provides a stress-distributing platform that reduces stress on subsequent structural layers without requiring changes to the vertical layering sequence, thus managing complexity while improving strength.
3Reliability
If a thick single-layer silicon oxide is used, then insulation is improved, but water vapor can penetrate through defects leading to aging failures
Solution Approach 1:
The thick silicon oxide insulating layer is segmented into two layers with different thicknesses and potentially different material compositions. This segmentation creates multiple barriers to water vapor penetration, as defects in one layer may not align with defects in the other, thereby blocking water vapor transport paths and preventing aging failures while maintaining insulation quality.
Solution Approach 2:
The first and second insulating layers may be composed of different materials or have different densities, creating a composite insulating structure. This composite approach provides enhanced protection against water vapor penetration by combining the advantages of different materials, where each layer contributes unique properties that collectively block water vapor while maintaining insulation.
Data Source
AI summary
Provided is an LED chip, which includes a semiconductor stack layer and an insulating layer on the semiconductor stack layer. The insulating layer at least includes a first insulating layer and a second insulating layer. The insulating layer has a step structure including a first step formed by the first insulating layer and a second step formed by the second insulating layer. The first step extends beyond the second step in a horizontal direction. Since the insulating layer is formed by at least the first insulating layer and the second insulating layer, crack or whole-layer breaking of the insulating layer is avoided. The extended portion of the first insulating layer can play a buffering role, thereby reducing a stress generated inside the second structural layer, avoiding the second structural layer from cracking or whole-layer breaking, and improving the reliability of the LED chip.