AlN Template Growth for Crack-Free UV LED Epitaxy
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Solution Overview
Problem
Existing methods for manufacturing semiconductor light-emitting elements, particularly those emitting ultraviolet light, face challenges such as the generation of microcracks and high crystalline defect densities in aluminum nitride templates due to lattice and thermal expansion coefficient mismatches, which affect the quality and reliability of the elements.
Innovation Solution
The method involves growing a high-temperature AlxGa1−xN layer with an inversion domain suppression layer and a support substrate, along with a stress adjustment layer, to manage stress and reduce defects, and using a V-shaped pit generation layer at high temperatures with specific doping concentrations to enhance crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick AlN layer is formed on a sapphire growth substrate to serve as an aluminum nitride template, then the thermal expansion coefficient and lattice constant match is improved, but microcracks are generated inside the AlN layer due to tensile stress from lattice and thermal expansion coefficient differences
Solution Approach 1:
The patent divides the AlN layer formation into multiple stages with different growth modes. A first AlN layer is grown in 3D growth mode to introduce air voids that relax tensile stress, followed by a second AlN layer grown in 2D growth mode to provide a smooth surface. This segmentation allows the thick AlN template to be formed without microcracks while maintaining template quality.
Solution Approach 2:
The patent performs preliminary stress relaxation by growing the first AlN layer in 3D growth mode before forming the main thick AlN template. The air voids created during this preliminary stage pre-relax the tensile stress that would otherwise cause microcracks in the final thick AlN layer, enabling crack-free template formation.
2Strength
If the AlN layer is grown in 3D growth mode to relax tensile stress and prevent microcracks, then crack resistance is improved, but the HT-AlN layer has crystallinity with both aluminum polarity and nitrogen polarity resulting in a rough surface
Solution Approach 1:
The patent segments the AlN layer formation into two distinct parts: a first AlN layer grown in 3D mode to provide stress relaxation and crack resistance, and a second AlN layer grown in 2D mode to provide surface smoothness. Each layer performs its specific function, resolving the contradiction between crack resistance and surface quality.
Solution Approach 2:
Different regions of the AlN template have different growth modes tailored to their specific functions. The lower portion (first AlN layer) uses 3D growth for stress relaxation, while the upper portion (second AlN layer) uses 2D growth for surface quality. This local differentiation allows each region to optimize its properties for its intended purpose.
3Reliability
If a thick AlN layer of 2 micrometers or more is formed to serve as an aluminum nitride template, then the template quality is improved, but fine microcracks are generated inside the AlN layer due to tensile stress
Solution Approach 1:
The patent forms the thick AlN template in two sequential stages with different growth modes. The first stage grows an initial AlN layer in 3D mode to relax stress, and the second stage grows the remaining thickness in 2D mode to maintain low defect density. This segmentation enables the formation of a thick template without microcracks.
Solution Approach 2:
The patent changes the growth mode parameter from 3D to 2D between the two AlN layer formation stages. This parameter change allows the transition from stress-relaxation-dominated growth to quality-dominated growth, enabling the thick AlN layer to be formed with both stress relaxation and low defect density.
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 results in a high-quality aluminum nitride template with reduced defects, enabling the production of ultraviolet light-emitting diodes with improved reliability and efficiency.
Implementation Method 1
a plurality of air voids of a mechanism for relaxing tensile stress are introduced into the HT-AlN layer 20 or an interface between the HT-AlN layer 20 and the sapphire growth substrate 10 by appropriately applying a process of forming the HT-AlN layer 20 in a three-dimensional (3D) growth mode
Implementation Method 2
An aluminum nitride (AlN) template manufactured in such a manner may be used to grow a semiconductor layer including aluminum (Al)
Data Source
AI summary
The present disclosure relates to a method for manufacturing a semiconductor light emitting device through non-wire bonding, the method comprising the steps of: preparing a semiconductor light emitting die and a support substrate; attaching the semiconductor light emitting die to the support substrate while a second electrical path is exposed, the semiconductor light emitting die being attached such that a conductive bonding structure covering the entire second semiconductor region is tightly bonded to a bonding layer; removing the substrate; and electrically connecting the second electrical path to the remaining semiconductor region among a first semiconductor region and the second semiconductor region through electrical connection through deposition.