LED Die Stepped Substrate Thermal Protection
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Solution Overview
Problem
Existing light emitting diode (LED) dies face challenges in achieving optimal thermal and electrical characteristics, particularly in protecting the epitaxial stack and ensuring efficient heat transfer and electrical connectivity.
Innovation Solution
A light emitting diode (LED) die is fabricated with a stepped structure comprising a first substrate and a second substrate, forming a protective geometry around an epitaxial stack, which includes a p-type semiconductor layer, a multiple quantum well layer, and an n-type semiconductor layer, with both substrates providing high thermal and electrical conductivity and a method involving a carrier substrate, epitaxial stack formation, and separation into individual dice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-substrate LED die structure is used, then the fabrication process is simple, but the thermal and electrical performance is insufficient and the epitaxial stack lacks protection
Solution Approach 1:
The LED die structure is segmented into two distinct substrates: a first substrate supporting the epitaxial stack and a second substrate providing additional thermal and electrical pathways. This segmentation allows each substrate to be optimized for specific functions, improving overall thermal management and electrical performance while providing mechanical protection for the epitaxial stack
Solution Approach 2:
The patent introduces a vertical stacking dimension by placing a second substrate beneath the first substrate, creating a multi-layer configuration. This dimensional change enables enhanced heat dissipation pathways and electrical connectivity without increasing the lateral footprint, thereby improving thermal and electrical performance while protecting the epitaxial stack
2Object-affected harmful factors
If the first substrate has a larger area than the second substrate to form a protective overhang, then the epitaxial stack is better protected, but the heat transfer area is reduced
Solution Approach 1:
The patent applies different area dimensions to different substrates at different locations: the first substrate has a larger area providing lateral protection (overhang) for the epitaxial stack, while the second substrate is positioned beneath to provide thermal management. This local differentiation allows the protective function and thermal function to be optimized independently at different spatial locations
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 stepped structure enhances thermal and electrical performance by providing a protective overhang for the epitaxial stack and improved heat transfer, while allowing for efficient separation and mounting of the LED dice, resulting in improved LED performance.
Implementation Method 1
a multiple quantum well (MQW) layer located between the confinement layers configured to emit light
Implementation Method 2
both substrates providing high thermal and electrical conductivity
Data Source
AI summary
A method for fabricating a light emitting diode die includes the steps of providing a carrier substrate and forming an epitaxial structure on the carrier substrate including a first type semiconductor layer, a multiple quantum well (MQW) layer on the first type semiconductor layer configured to emit light, and a second type semiconductor layer on the multiple quantum well (MQW) layer. The method also includes the steps of forming a plurality of trenches through the epitaxial structure, forming a reflector layer on the second type semiconductor layer, forming a seed layer on the reflector layer and in the trenches, and forming a substrate on the seed layer having an area configured to protect the epitaxial structure.