Oxidized AlN Film for Micro LED Defect Reduction
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Solution Overview
Problem
The challenge in manufacturing micro LEDs is the high defect density due to crystal lattice mismatches and threading dislocations between gallium nitride and sapphire substrates, which reduces brightness and luminous intensity, particularly exacerbated in smaller micro LEDs.
Innovation Solution
A semiconductor component with an oxidized aluminum nitride (AlN) film is introduced, featuring an AlN-buffer layer on a patterned substrate with an oxidized-AlN film partially disposed on protrusions, allowing for controlled growth of gallium nitride compound crystals by adjusting the thickness of the oxidized-AlN film between 0.5 nm and 4.5 nm, and employing MOCVD at high temperatures to partially burn out the oxidized-AlN film, exposing the AlN-buffer layer and reducing threading dislocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gallium nitride is grown on sapphire substrate using MOCVD, then LED epitaxial wafer can be formed, but crystal lattice mismatches and threading dislocations occur reducing brightness and luminous intensity
Solution Approach 1:
An AlN-buffer layer is introduced as an intermediary between the sapphire substrate and the gallium nitride epitaxial structure. This buffer layer serves as a transition medium that reduces the crystal lattice mismatch and threading dislocations, thereby improving crystal quality and subsequently enhancing brightness and luminous intensity of the micro LEDs
Solution Approach 2:
The oxidized-AlN film is selectively disposed only on the protrusions of the patterned substrate surface, while the AlN-buffer layer on the bottom portion remains exposed without oxidized-AlN film. This local differentiation allows controlled growth rates of gallium nitride crystals in different regions, optimizing crystal quality and reducing defects locally to improve overall brightness
2Volume of moving object
If micro LEDs are made smaller to reduce display size, then portability is improved, but defect density increases and brightness decreases
Solution Approach 1:
The patterned substrate with protrusions and the selective oxidation of AlN-buffer layer on protrusions create local variations in growth conditions. This allows precise control of gallium nitride crystal growth rates in different regions, enabling high-quality crystal formation even in smaller micro LED structures, thereby maintaining brightness while reducing size
Solution Approach 2:
The vacuum-cooling chamber process uses vacuum environment and controlled cooling to form the oxidized-AlN film with precise thickness control (0.5-4.5 nm). This pneumatic control mechanism enables accurate manipulation of film formation conditions, ensuring optimal crystal growth and defect reduction in miniaturized micro LEDs
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 effectively reduces defect density and enhances the luminous intensity and brightness of micro LEDs by controlling the growth rates of gallium nitride crystals on the substrate, resulting in evenly distributed and flat epitaxial structures.
Implementation Method 1
employ a physical vapor deposition to form an AlN-buffer layer on a patterned surface of a substrate
Implementation Method 2
transport the substrate to a vacuum-cooling chamber to cool down. By adjusting a quality of vacuum, temperature and/or cool-down time of the vacuum-cooling chamber, to further control a thickness of an oxidized-AlN film that is formed on the AlN-buffer layer
Implementation Method 3
The MOCVD process is required to be performed in a high-temperature environment about 400° C. or higher, such that the oxidized-AlN film on the substrate is partially burnt out and removed in the high-temperature environment, thereby to partially expose the AlN-buffer layer
Data Source
AI summary
The present disclosure is a light-emitting diode (LED) with oxidized aluminum nitride (oxidized-AlN) film, which includes a substrate, an aluminum nitride buffer (AlN-buffer) layer, an oxidized-AlN film and a light-emitting diode epitaxial structure. The AlN-buffer layer is disposed on a patterned surface of the substrate, wherein the patterned surface is formed with a plurality of protrusions and a bottom portion. The oxidized-AlN film is disposed on the AlN-buffer layer on the protrusions, and with none disposed on the AlN-buffer layer on the bottom portion. The LED epitaxial structure includes gallium nitride compound crystal formed on the oxidized-AlN film and the AlN-buffer layer, to effectively reduce defect density of the gallium nitride compound crystal and to improve a luminous intensity of the LED.