Laser Beam Scanning for High-Throughput LED Wafer Lift-Off
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Solution Overview
Problem
As wafer diameters for LED production increase, the throughput in processing individual LEDs decreases due to heat accumulation and damage from larger laser beam spot diameters used to break the buffer layer, leading to inefficient processing and potential LED damage.
Innovation Solution
A laser processing apparatus with a chuck table and laser beam irradiation unit that uses a combination of X-axis and Y-axis scanners, a beam condenser, and specific settings for spot diameter, overlap rate, scan speeds, and energy per pulse to maintain high throughput while preventing heat accumulation and LED damage, with a spot diameter of 5 to 60 μm and an overlap rate of 0.70 to 0.99, ensuring efficient processing without increasing the spot diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spot diameter is increased to enhance throughput, then the processing speed improves, but heat accumulation occurs and LEDs near the irradiation position are damaged
Solution Approach 1:
The patent segments the laser beam processing into multiple overlapping spots with controlled parameters. By dividing the processing area into discrete spots with specific overlap rates (0.70-0.99), the system achieves high throughput while distributing heat accumulation across multiple smaller interaction zones rather than one large spot, thereby preventing localized overheating and LED damage
Solution Approach 2:
The patent applies parameter changes by optimizing multiple laser processing parameters simultaneously: spot diameter (5-60 μm), overlap rate (0.70-0.99), scan speed (1-300 m/s), energy per pulse (0.07-50 μJ), and repetition frequency. This multi-parameter optimization enables high throughput processing while maintaining safe temperature levels that prevent LED damage
2Object-affected harmful factors
If the spot diameter is kept small to prevent heat accumulation, then LED damage is avoided, but throughput decreases
Solution Approach 1:
The patent achieves continuous effective processing by maintaining high overlap rates (0.70-0.99) between consecutive laser spots. This ensures that the small spot diameter (5-60 μm) processing is performed in a continuous overlapping pattern rather than discrete separate spots, thereby maintaining high throughput while keeping each individual spot small enough to prevent heat accumulation and LED damage
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 solution effectively suppresses average output power, preventing heat accumulation and LED damage, while maintaining high throughput and efficiently transferring the light emitting layer to a transfer substrate, even with a small spot diameter, thus enhancing processing efficiency.
Implementation Method 1
a laser beam irradiation unit that irradiates a workpiece with a laser beam to form a broken layer
Data Source
AI summary
A laser beam irradiation unit of a laser processing apparatus includes a laser oscillator that oscillates a laser, a Y-axis scanner that executes a high-speed scan with a laser beam emitted from the laser oscillator in a Y-axis direction, an X-axis scanner that executes processing feed of the laser beam emitted from the laser oscillator in an X-axis direction, and a beam condenser. The Y-axis scanner is selected from any of an AOD, a resonant scanner, and a polygon scanner and the X-axis scanner is selected from a galvano scanner and a resonant scanner.