Light-Emitting Structure With DBR Layout for Crack-Free Dicing
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Solution Overview
Problem
Existing light-emitting devices face challenges in maintaining reliability due to cracking defects in the reflective layer during the dicing process, which can lead to moisture intrusion and reduced device reliability.
Innovation Solution
A light-emitting device design featuring a substrate with a dicing street that exposes the top surface and a semiconductor stack, where the reflective layer is formed with a Distributed Bragg Reflector structure, and a cap layer is applied without covering the second top surface, along with a compact layer for improved film quality and moisture prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the reflective layer is formed to cover the entire substrate surface including the dicing street area, then the light extraction efficiency is improved, but cracking defects occur during the dicing process leading to reduced reliability
Solution Approach 1:
The reflective layer is selectively positioned to cover only the light-emitting area of the substrate, leaving the dicing street area uncovered. This local differentiation allows the reflective layer to enhance light extraction where needed while avoiding the dicing street region where cracking would compromise reliability during the dicing process.
2Reliability
If the protective layer and cap layer are extended to cover the entire substrate surface, then moisture protection is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The protective layer and cap layer are configured to cover only the light-emitting area where moisture protection is critical, rather than extending across the entire substrate surface including the dicing street. This localized approach provides adequate moisture protection for the functional area while reducing structural complexity and manufacturing difficulty.
3Illumination intensity
If the reflective layer is formed with full coverage, then light extraction efficiency is improved, but the dicing process becomes more difficult due to cracking defects
Solution Approach 1:
The reflective layer is strategically positioned to cover only the light-emitting area, creating a local quality distinction that maintains high light extraction efficiency where the layer is present while eliminating the presence of the layer in the dicing street area. This absence in the dicing region prevents cracking defects and facilitates easier dicing processing.
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 design enhances the light-emitting device's reliability by reducing cracking defects and preventing moisture intrusion, thereby improving the overall performance and longevity of the device.
Implementation Method 1
a reflective layer comprising a Distributed Bragg Reflector structure covering the protective layer
Data Source
AI summary
A light-emitting device comprises a substrate comprising a sidewall, a first top surface, and a second top surface, wherein the second top surface is closer to the sidewall of the substrate than the first top surface to the sidewall of the substrate; a semiconductor stack formed on the substrate comprising a first semiconductor layer, an active layer, and a second semiconductor layer; a dicing street surrounding the semiconductor stack, and exposing the first top surface and the second top surface of the substrate; a protective layer covering the semiconductor stack; a reflective layer comprising a Distributed Bragg Reflector structure covering the protective layer; and a cap layer covering the reflective layer, wherein the second top surface of the substrate is not covered by the protective layer, the reflective layer, and the cap layer.