Group III Nitride Light-Emitting Elements via Chemical Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Deep ultraviolet light-emitting elements using group III nitride semiconductors face low light extraction efficiency and are prone to physical damage during the cutting process, leading to reduced yield and light output power due to chipping, breakage, and cracking.
Innovation Solution
A method involving chemical etching to separate the light-emitting elements, creating an inclined surface on the substrate to enhance light extraction efficiency and avoid physical cutting methods, which reduces damage and increases yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical cutting methods (diamond scribing, laser scribing) are used to separate light-emitting elements from the wafer, then element separation can be achieved, but chipping, breakage, and cracking occur causing reduced yield
Solution Approach 1:
The patent replaces mechanical cutting methods (diamond scribing, laser scribing) with chemical etching using a specific etchant solution. This substitution eliminates physical contact and mechanical stress that cause chipping, breakage, and cracking, thereby maintaining element integrity while achieving separation. The chemical etching process uses a etchant containing ammonium fluoride and hydrogen fluoride to selectively remove the substrate material without damaging the light-emitting elements.
Solution Approach 2:
The patent changes the separation mechanism from mechanical force to chemical reaction by introducing a specific etchant composition (ammonium fluoride and hydrogen fluoride in specific ratios). This parameter change allows controlled chemical dissolution of the substrate at the scribing lines, enabling clean separation without physical damage to the brittle light-emitting elements.
2Ease of manufacture
If conventional cutting methods are used, then wafer separation is possible, but cracks enter into the inside of light-emitting elements causing leakage and lowered yield
Solution Approach 1:
The patent replaces mechanical cutting tools with a chemical etching process that uses a etchant solution to selectively remove substrate material. This eliminates mechanical contact that causes cracks and internal damage, while maintaining manufacturing simplicity through a straightforward immersion or spray process.
Solution Approach 2:
The patent introduces a chemical etchant as an intermediary substance that mediates the separation process. The etchant (containing ammonium fluoride and hydrogen fluoride) selectively reacts with the substrate material at the scribing lines, enabling clean separation without direct mechanical contact that would cause cracking or internal damage to the light-emitting elements.
3Illumination intensity
If deep ultraviolet light-emitting elements are produced, then semiconductor-based light source is achieved, but light extraction efficiency remains low
Solution Approach 1:
The patent applies curvature to the lower surface of the light-emitting element by forming hemispherical or dome-shaped protrusions. This curved geometry increases the extraction angle for generated light, allowing more light to escape the high-refractive-index semiconductor material. The curved surfaces reduce total internal reflection and improve light extraction efficiency, thereby increasing overall light output power.
Solution Approach 2:
The patent adds a third dimension to the light extraction problem by creating three-dimensional curved protrusions on the lower surface. This dimensional change transforms the flat extraction interface into a multi-faceted curved surface, increasing the solid angle for light extraction and improving efficiency without affecting the planar active layer structure.
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 significantly improves light extraction efficiency and production yield by avoiding physical damage during separation, maintaining high precision and accuracy in producing group III nitride light-emitting elements.
Implementation Method 1
A method involving chemical etching to separate the light-emitting elements, creating an inclined surface on the substrate to enhance light extraction efficiency
Data Source
AI summary
A group III nitride semiconductor light-emitting element includes a single crystal substrate and an element layer. The element layer includes an n-type layer, an active layer, and a p-type layer formed on the upper surface of the single crystal substrate in this order, and has a composition represented by the composition formula AlXGaYIn1-X-YN (0≤X≤1.0, 0≤Y≤1.0, 0≤X+Y≤1.0). The thickness of the single crystal substrate is at least 80 μm. The area of the upper surface of the substrate is larger than the area of the bottom surface of the substrate.