LED Substrate Cleaving via Laser-Induced Cracks and Wavelength Conversion Recesses
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Solution Overview
Problem
The existing methods for manufacturing light-emitting devices, particularly those using single crystal sapphire substrates, face challenges in yield improvement due to substrate chipping and inefficient cleaving processes during the singulation of light-emitting devices.
Innovation Solution
A method involving the formation of a crack inside the substrate using a laser beam, followed by the disposition of a wavelength conversion layer and strategic removal of portions to create recesses, allowing for cleaving along the crack to improve yield and reduce chipping, enhancing the light extraction efficiency and luminance of the devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional sawing method is used for singulation, then the light-emitting device can be separated into individual units, but substrate chipping occurs and yield decreases
Solution Approach 1:
The patent divides the substrate into multiple regions by forming separate cracks at different positions, allowing independent cleaving of each region. This segmentation approach enables precise control over where the substrate is separated, preventing chipping at critical areas while maintaining high yield through systematic singulation of LED chips.
Solution Approach 2:
The patent performs preliminary crack formation and wavelength conversion layer removal before the final cleaving step. By pre-forming cracks and removing material in advance, the substrate is prepared for clean separation, reducing the risk of chipping during the actual singulation process and improving overall yield.
2Manufacturing precision
If crack formation is performed without wavelength conversion layer removal, then the process is simpler, but cleaving precision is reduced and chipping increases
Solution Approach 1:
The patent extracts the wavelength conversion layer from specific regions before cleaving. By removing this layer in advance from areas where precision cleaving is critical, the substrate can be separated more accurately along predetermined lines, reducing chipping and improving cleaving precision despite adding an extra process step.
Solution Approach 2:
The wavelength conversion layer is removed in advance before the cleaving operation. This preliminary removal of material that would interfere with precise cleaving allows for cleaner separation lines and reduces the likelihood of chipping, thereby improving manufacturing precision.
3Ease of manufacture
If the wavelength conversion layer is completely removed, then cleaving is easier, but light extraction efficiency is reduced
Solution Approach 1:
The patent applies different treatments to different regions of the wavelength conversion layer. In some areas, the layer is completely removed to facilitate easy cleaving, while in other areas, portions are retained to maintain light extraction efficiency. This localized differentiation allows the process to optimize for both ease of manufacture and optical performance in different regions.
Solution Approach 2:
The wavelength conversion layer is selectively removed from specific segments or regions of the substrate rather than uniformly across the entire surface. This segmentation allows certain areas to be optimized for cleaving ease while preserving light extraction functionality in other areas, resolving the contradiction between manufacturing ease and optical performance.
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 enhances the yield and luminance of light-emitting devices by reducing substrate chipping and improving the precision of cleaving, leading to better-shaped lateral surfaces and increased light extraction efficiency.
Implementation Method 1
forming a crack inside the substrate, the crack reaching the first surface of the substrate
Implementation Method 2
forming a crack inside the substrate
Implementation Method 3
disposing a wavelength conversion layer on the second surface of the substrate
Data Source
AI summary
A method of manufacturing a light-emitting device includes: providing a substrate having a first surface and a second surface opposite to the first surface; forming, on or above the first surface of the substrate, a semiconductor structure comprising a light-emitting layer; forming a crack inside the substrate, the crack reaching the first surface of the substrate; disposing a wavelength conversion layer on the second surface of the substrate; forming a first recess in the wavelength conversion layer by removing a first portion of the wavelength conversion layer, the first portion overlapping with the crack when viewed in a direction from the wavelength conversion layer toward the semiconductor structure, and leaving a second portion of the wavelength conversion layer between the first recess and the semiconductor structure; and cleaving the second portion along the crack.