Laser Dicing LED Wafer Textured Substrate
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LED wafer dicing methods suffer from reduced yield and light extraction efficiency due to debris and particle absorption, especially as substrate thickness increases, leading to decreased brightness and light extraction.
Innovation Solution
The method involves using a first laser to form scribing lines on the upper surface and a second laser to create textured areas within the substrate, followed by force separation of the wafer into chips, with optional repeated stealth dicing lasers to guide splitting and enhance light extraction, and a wet-etching process to remove debris, while maintaining the semiconductor stack integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dicing method with saw is used to divide wafer into LED chips, then the wafer can be separated into chips, but debris and particles are generated and remain on LED chip surface causing light absorption and deteriorating light extraction efficiency
Solution Approach 1:
The patent replaces the conventional mechanical saw dicing system with a laser-based dicing system. The laser beam performs the cutting action without physical contact, eliminating the generation of debris and particles that plague mechanical dicing methods. This substitution of mechanical energy with optical energy resolves the contradiction by maintaining dicing efficiency while eliminating harmful debris contamination.
Solution Approach 2:
The laser dicing process utilizes phase transition of material through ablation. The concentrated laser energy causes localized vaporization and phase change of the material being cut, enabling clean separation without mechanical contact. This phase transition mechanism allows precise cutting while avoiding the debris generation inherent in mechanical dicing, thus improving light extraction efficiency.
2Strength
If substrate thickness is increased to improve chip strength and light extraction area, then chip brightness can be enhanced, but dicing yield is degraded due to increased difficulty in separating thick substrates
Solution Approach 1:
The laser dicing system replaces mechanical saw cutting with optical energy delivery. This allows efficient cutting through thicker substrates without the mechanical limitations and yield losses associated with conventional dicing. The laser can penetrate and cut through increased substrate thickness while maintaining high yield by avoiding mechanical stress and fragmentation issues.
Solution Approach 2:
The laser dicing approach enables cutting from both the top and bottom surfaces of the wafer simultaneously or sequentially. This multi-directional approach to dicing thick substrates allows for better control and higher yield by distributing the cutting stress and enabling more effective separation of thick materials that would be difficult to dice with conventional single-side mechanical methods.
3Device complexity
If conventional mechanical dicing is used, then simple process is maintained, but light extraction efficiency deteriorates due to debris absorption on chip surface
Solution Approach 1:
The patent replaces mechanical dicing with laser dicing, substituting optical energy for mechanical energy. This substitution eliminates the harmful side effect of debris generation while the added complexity of laser systems is offset by the elimination of subsequent cleaning steps and the improvement in product quality. The process complexity increases slightly but the harmful effects are eliminated.
4Object-affected harmful factors
If repeated stealth dicing lasers are applied to guide splitting and enhance light extraction, then light extraction efficiency is improved, but process complexity increases
Solution Approach 1:
The laser dicing system performs multiple functions: it creates the initial scribing lines, guides the splitting process, and enhances light extraction through repeated applications. This multi-functionality consolidates several operations into a single system, improving light extraction efficiency without proportionally increasing overall process complexity. The same laser tool is used for multiple purposes throughout the dicing process.
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 improves light extraction efficiency and yield by reducing debris-related absorption, enhancing light extraction angles, and maintaining chip brightness, with optimized substrate thickness and laser application strategies.
Implementation Method 1
providing a first laser on the light-emitting diode wafer and irradiating the light-emitting diode wafer from the upper surface to form a plurality of scribing lines on the upper surface
Implementation Method 2
providing and focusing a second laser on an interior of the substrate to form one or a plurality of textured areas in the substrate
Implementation Method 3
providing force on the light-emitting diode wafer to separate the light-emitting diode wafer into a plurality of light-emitting diode chips along the plurality of scribing lines
Data Source
AI summary
A method of manufacturing a light-emitting device is disclosed. The method includes providing a light-emitting diode wafer, including a substrate and a semiconductor stack on the substrate, wherein the semiconductor stack has a lower surface facing the substrate and an upper surface opposite to the lower surface; providing a first laser on the light-emitting diode wafer and irradiating the light-emitting diode wafer from the upper surface to form a plurality of scribing lines on the upper surface; providing an etching process; providing and focusing a second laser on an interior of the substrate to form one or a plurality of textured areas in the substrate; and providing force on the light-emitting diode wafer to separate the light-emitting diode wafer into a plurality of light-emitting diode chips along the plurality of scribing lines.