LED Structure Porous Silicon Substrate Removal
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Solution Overview
Problem
Silicon substrates used in LED manufacturing have a high light absorption rate, reducing light efficiency, and existing methods to address this either compromise crystal quality or require costly and time-consuming substrate removal.
Innovation Solution
A method involving the formation of a porous layer on a conductive substrate, allowing for the separation of the LED structure from the silicon substrate while maintaining electrical connection, which includes steps like electro-chemical anodization and selective etching to minimize substrate loss and enhance light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective layer is added to reduce silicon substrate light absorption, then light efficiency is improved, but crystal quality of epitaxially grown group III-V layers deteriorates
Solution Approach 1:
The patent extracts the problematic silicon substrate from the final LED structure by forming a porous silicon layer that can be selectively removed. This allows the LED to be separated from the substrate after epitaxial growth, eliminating the need for a reflective layer and preserving crystal quality while maintaining light efficiency.
Solution Approach 2:
The porous silicon layer acts as an intermediary that enables both functions: it provides a release mechanism for substrate removal while allowing epitaxial growth during manufacturing. The porous structure facilitates selective etching without damaging the overlying LED structure.
2Loss of energy
If the silicon substrate is removed and replaced with a new conductive substrate, then light efficiency is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent performs preliminary action by forming the porous silicon layer during the original substrate preparation stage, before LED fabrication. This pre-prepared porous layer enables rapid substrate removal later without requiring additional time-consuming processes, thus improving manufacturing efficiency while achieving the goal of removing the light-absorbing substrate.
3Loss of energy
If the silicon substrate is completely removed, then light efficiency is improved, but substrate waste increases and cost increases
Solution Approach 1:
The patent segments the silicon substrate into two parts: a porous silicon layer that is removed with the LED structure, and a remaining silicon substrate that can be reused. This segmentation allows selective removal of only the necessary portion while preserving the bulk substrate for multiple reuse cycles, reducing waste and cost.
Solution Approach 2:
The patent implements discarding and recovering by selectively removing the porous silicon layer containing the LED structure while recovering and reusing the remaining silicon substrate. The substrate can be prepared for subsequent LED fabrication cycles, reducing material waste and manufacturing costs.
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 approach improves light efficiency by reducing substrate absorption and allowing for the reuse of silicon substrates, thereby reducing waste and costs, while maintaining crystal quality and enhancing light reflection.
Implementation Method 1
The forming of the porous layer includes a step of converting the dopes layed to the porous layer
Data Source
AI summary
A method of forming a light-emitting diode (LED) device is provided. The method includes steps of providing a first substrate, forming an LED structure on the first substrate, forming a porous layer on the first substrate after forming the LED structure, forming a conductive substrate on the LED structure, and separating the LED structure from the first substrate along the porous layer. The substrate has a doped layer. The forming of the porous layer includes a step of converting the dopes layer to the porous layer.