Nitride Semiconductor Protrusions for Light Extraction
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Solution Overview
Problem
Nitride semiconductor light-emitting devices face challenges in light extraction efficiency due to total reflection of photons within the device and increased dislocation density caused by lattice constant differences between substrates and semiconductor layers, leading to complex manufacturing processes and increased costs.
Innovation Solution
A method involving a combination of dry-etching and wet-etching processes to form protrusions on the substrate surface for growing nitride semiconductor materials, which improves light extraction efficiency and reduces dislocation density by using a sapphire substrate and additional semiconductor layers, allowing for better light emission and internal quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a stacking-structure wall with a predetermined angle is formed to extract transverse light, then light extraction efficiency is improved, but manufacturing process complexity increases and manufacturing cost increases
Solution Approach 1:
The patent forms protrusions with curved surfaces on the substrate instead of using flat stacking-structure walls. The protrusions have a hemispherical or dome-shaped top surface that gradually curves downward to the substrate, which simplifies the manufacturing process while still achieving effective light extraction through the curved interface between the protrusion and the surrounding medium.
Solution Approach 2:
The patent changes the geometric parameters of the substrate structure by forming protrusions with specific height, diameter, and curvature radius ratios. By optimizing these parameters, the patent achieves effective light extraction without requiring complex stacking structures, thereby simplifying the manufacturing process while maintaining improved light extraction efficiency.
2Ease of manufacture
If dry-etching alone is used to form protrusions, then manufacturing process is simpler, but byproducts remain on the substrate surface reducing semiconductor layer quality
Solution Approach 1:
The patent combines dry-etching and wet-etching processes in sequence. The dry-etching process first forms the protrusion structure, and then the wet-etching process removes the byproducts from the substrate surface. This combination of two processes achieves both the structural formation and the surface cleaning, thereby improving semiconductor layer quality without significantly complicating the manufacturing process.
Solution Approach 2:
The patent implements a continuous manufacturing process where dry-etching and wet-etching are performed in immediate succession without intermediate steps. The wet-etching process continuously removes byproducts generated during dry-etching, ensuring that the substrate surface is always clean and ready for subsequent semiconductor layer deposition, thereby maintaining high manufacturing precision throughout the process.
3Ease of manufacture
If a flat substrate surface is used, then manufacturing process is simpler, but dislocation density increases due to lattice constant difference between substrate and semiconductor layer
Solution Approach 1:
The patent applies local quality by creating protrusions with specific geometric characteristics on the substrate surface. The protrusions have different heights, diameters, and curvature radii that are locally optimized to reduce dislocation density in the overlying semiconductor layers. This local structural modification allows the bulk of the substrate to remain simple while the protrusion regions provide dislocation reduction benefits.
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 method enhances light extraction efficiency by 40% and internal quantum efficiency by 10%, simplifying the manufacturing process and reducing costs by effectively removing byproducts and improving semiconductor layer quality.
Implementation Method 1
wet-etching the dry-etched substrate through the use of etching solution
Implementation Method 2
forming protrusions on the substrate by dry-etching the substrate with the mask pattern through the use of etching gas
Implementation Method 3
forming a first semiconductor layer on the substrate including the protrusions
Data Source
AI summary
Disclosed is a method for manufacturing a semiconductor light-emitting device, which carries out a wet-etching process after a dry-etching process so as to form protrusions in a surface of a substrate for growing a nitride semiconductor material thereon. The method comprises coating a substrate with photoresist; forming a mask pattern on the substrate by selectively removing the photoresist; forming protrusions on the substrate by dry-etching the substrate with the mask pattern through the use of etching gas; wet-etching the dry-etched substrate through the use of etching solution; forming a first semiconductor layer on the substrate including the protrusions; forming an active layer on the first semiconductor layer; forming a second semiconductor layer on the active layer; etching predetermined portions of the active layer and second semiconductor layer until the first semiconductor layer is exposed; and forming a first electrode on a predetermined portion of the first semiconductor layer, wherein the active layer and second semiconductor layer are not formed on the predetermined portion of the first semiconductor layer, and forming a second electrode on the second semiconductor layer.