GaN Light Emitting Structure Fabrication via Sacrificial Layer Etching
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Solution Overview
Problem
The existing methods for fabricating semiconductor light emitting diodes (LEDs) face challenges in reducing damage and degradation during the separation of the growth substrate, which can lead to reduced production yield due to high temperatures and potential damage to the semiconductor layer.
Innovation Solution
A method involving the formation of a sacrificial layer with nanostructures on a growth substrate, covered by a protective layer, followed by growing light emitting structures and separating them using chemical wet etching, which reduces thermal and physical impacts and allows for easier substrate recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a laser lift-off (LLO) process is used to separate the growth substrate from the semiconductor layer, then the separation can be achieved, but the semiconductor layer may be degraded or damaged due to high temperatures from the laser beam
Solution Approach 1:
The patent introduces an organic sacrificial layer as an intermediary between the sapphire substrate and the GaN semiconductor layer. This sacrificial layer can be selectively removed by chemical etching (using KOH or HF solutions) without affecting the semiconductor layer, thereby enabling substrate separation while protecting the semiconductor layer from laser-induced thermal damage
Solution Approach 2:
The patent replaces the laser-based thermal separation method with a chemical etching method. Instead of using high-energy laser beams that cause thermal damage, the process uses chemical solutions to selectively dissolve the organic sacrificial layer, achieving separation through chemical rather than thermal means
2Reliability
If the growth substrate is separated from the light emitting structure, then light extraction efficiency is improved, but production yield is reduced due to damage and degradation of the semiconductor layer
Solution Approach 1:
The organic sacrificial layer serves as a mediator that enables clean separation between the sapphire substrate and the GaN layer. By designing this intermediate layer with specific chemical properties (solubility in KOH or HF), the patent achieves substrate removal without compromising semiconductor layer quality, thus improving both light extraction efficiency and production yield
Solution Approach 2:
The patent changes the chemical composition and properties of the sacrificial layer to enable selective removal. By controlling the chemical parameters of the sacrificial layer (making it soluble in specific etchants while being insoluble in others), the process achieves selective substrate separation that preserves semiconductor layer integrity, thereby maintaining high production yield
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 minimizes damage to the light emitting structure during substrate separation, enhancing the production yield and stability of the semiconductor light emitting device while allowing for simpler substrate recycling.
Implementation Method 1
separating the light emitting structure from the growth substrate by etching the exposed nanostructures
Implementation Method 2
etching the protective layer to expose the nanostructures
Data Source
AI summary
There is provided a method of fabricating a semiconductor light emitting device, including: forming a sacrificial layer having a plurality of nanostructures on a growth substrate; forming a protective layer to cover the sacrificial layer; forming a light emitting structure by allowing a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer to be sequentially grown on the protective layer; etching the protective layer to expose the nanostructures; and separating the light emitting structure from the growth substrate by etching the exposed nanostructures, whereby damage and degradation of a light emitting structure at the time of the separation thereof may be prevented.