Two-Stage Laser Irradiation for Sapphire Substrate Dicing
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Solution Overview
Problem
The existing methods for manufacturing light-emitting elements using laser beam irradiation often result in unintended cracking and degradation of the semiconductor layer, leading to poor electrical characteristics and appearance defects.
Innovation Solution
A method involving a two-stage laser beam irradiation process on a sapphire substrate, where the first modified portions are formed closer to the semiconductor layer with a shorter length and the second modified portions are formed farther away with a greater length, reducing unintended cracking and degradation by optimizing the fracture strength and light concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a laser beam is concentrated in the substrate interior to form modified portions for wafer dicing, then the wafer can be cleaved effectively, but unintended cracking occurs and the electrical characteristics of the semiconductor layer degrade
Solution Approach 1:
The patent divides the single laser irradiation process into two separate irradiation processes: a first irradiation process that forms first modified portions at a first depth, and a second irradiation process that forms second modified portions at a second depth. This segmentation allows independent optimization of each irradiation process to achieve both effective dicing and protection of the semiconductor layer.
Solution Approach 2:
The patent creates different modified portions at different depths within the sapphire substrate. The first modified portions are formed at a first depth with specific characteristics, while the second modified portions are formed at a second depth with different characteristics. This local differentiation allows the upper modified portions to guide crack propagation away from the semiconductor layer while the lower modified portions provide sufficient stress concentration for effective dicing.
2Productivity
If the laser beam is irradiated to form modified portions for separation, then the wafer can be separated into light-emitting elements, but unintended cracking occurs after irradiation
Solution Approach 1:
The patent performs the first irradiation process before the second irradiation process. The first modified portions are formed in advance to create initial stress concentration points and guide crack propagation paths. The second irradiation process then reinforces these paths or creates additional controlled modification points, ensuring that subsequent separation follows predetermined safe paths away from the semiconductor layer.
Solution Approach 2:
The patent utilizes the depth dimension within the sapphire substrate by forming modified portions at two distinct depths (first depth and second depth). This three-dimensional arrangement of modified portions allows control over crack propagation in the vertical dimension, directing cracks away from the semiconductor layer located at the first surface while maintaining effective separation capability.
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 unintended cracking and degradation of the semiconductor layer, enhancing the electrical characteristics and reducing appearance defects, while increasing the fracture strength of the sapphire substrate.
Implementation Method 1
a laser beam irradiation process of irradiating a laser beam into the sapphire substrate from the second surface side
Data Source
AI summary
A method for manufacturing a light-emitting element includes preparing a wafer; a laser beam irradiation process; and a separation process. The laser beam irradiation process includes a first irradiation process of forming a plurality of first modified portions, and a second irradiation process of forming a plurality of second modified portions. The second modified portions are formed in the second irradiation process so that a length in a thickness direction of the sapphire substrate of the second modified portions is greater than a length in the thickness direction of the first modified portions.