LED Chip Reflective Structure for Stealth Dicing
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Solution Overview
Problem
Conventional stealth dicing methods for LED chips risk damaging the epitaxial structure due to scattered laser beams, leading to potential current leakage and troubleshooting challenges.
Innovation Solution
A light-emitting diode (LED) chip design featuring a reflective structure with a reflectance of less than 30% for specific wavelengths, incorporating a distributed Bragg reflector (DBR) structure that forms an optical waveguide or absorbs scattered laser light, preventing damage to the epitaxial structure during stealth dicing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional stealth dicing is performed with high reflectance reflective structure, then dicing precision is improved, but the scattered laser beam damages the epitaxial structure causing current leakage
Solution Approach 1:
The patent changes the reflectance parameter of the reflective structure from conventional high reflectance (about 20% for laser beam) to low reflectance (less than 30% for dicing laser wavelength). This parameter change allows the reflective structure to absorb scattered laser beams during stealth dicing rather than reflecting them back into the epitaxial structure, preventing damage and current leakage while maintaining dicing precision
Solution Approach 2:
The patent converts the harmful effect of scattered laser beams (which normally reflect off high reflectance structures and damage the epitaxial structure) into a beneficial effect by using low reflectance materials that absorb the scattered light. The scattered laser beams that would otherwise cause damage are now absorbed by the reflective structure, protecting the epitaxial structure from damage
2Use of energy by moving object
If high reflectance reflective structure is used, then light extraction efficiency is improved, but scattered laser beam during dicing causes damage to semiconductor structure
Solution Approach 1:
The patent applies parameter changes by selecting reflective structure materials with low reflectance characteristics for the dicing laser wavelength. This allows the same reflective structure to perform both functions: extracting LED emission light efficiently (through its inherent reflective properties for LED wavelength) while absorbing scattered dicing laser beams (through low reflectance for laser wavelength), thereby preventing laser beam damage
Solution Approach 2:
The patent applies local quality by designing the reflective structure with wavelength-selective optical properties. The reflective structure has different optical characteristics for different wavelengths: it maintains high reflectance for LED emission wavelengths to ensure light extraction efficiency, while having low reflectance for dicing laser wavelengths to absorb scattered beams and prevent damage
3Ease of manufacture
If conventional reflective structure is used, then manufacturing simplicity is maintained, but troubleshooting current leakage becomes difficult
Solution Approach 1:
The patent applies preliminary anti-action by proactively preventing current leakage through the low reflectance reflective structure design before it can occur. By absorbing scattered laser beams during dicing, the reflective structure prevents epitaxial structure damage from happening in the first place, eliminating the need for subsequent troubleshooting and repair of current leakage issues
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 solution effectively minimizes damage to the semiconductor epitaxial structure by guiding or absorbing scattered laser beams, reducing the risk of current leakage and enhancing the reliability of LED chips and associated devices.
Implementation Method 1
The reflective structure has a reflectance of less than 30% for light having a first wavelength which is different from a wavelength of light emitted from the semiconductor epitaxial structure
Implementation Method 2
A part of the reflective structure disposed on the side surfaces of the semiconductor epitaxial structure forms an optical waveguide structure to allow light having a first wavelength, upon entering the optical waveguide structure, to be transmitted therethrough and emitted outwardly
Data Source
AI summary
A light-emitting diode (LED) chip includes a semiconductor epitaxial structure and a reflective structure. The reflective structure is formed on an upper surface and side surfaces of the semiconductor epitaxial structure. The reflective structure has a reflectance of less than 30% for light having a first wavelength which is different from a wavelength of light emitted from the semiconductor epitaxial structure. A semiconductor light-emitting device including the LED chip, and a display device including a plurality of the LED chips are also disclosed.