Laser Dicing Pulse Picker Synchronization for Sapphire Substrates
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Solution Overview
Problem
Current laser dicing methods using pulse laser beams face challenges in achieving precise and efficient cleavage of semiconductor substrates, particularly hard substrates like sapphire, with minimal external force and without degrading elements such as LEDs formed on the substrate surface.
Innovation Solution
A laser dicing method that synchronizes a pulse laser beam with a clock signal to control the irradiation and non-irradiation of the substrate in units of light pulses, using a pulse picker to manage the passage and cutoff of the laser beam, allowing for controlled crack formation on the substrate surface by adjusting the irradiation energy, processing point depth, and lengths of irradiation and non-irradiation regions, thereby minimizing cleaving force and preserving substrate integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pulse laser beam is used for dicing of a semiconductor substrate, then the substrate can be cut with a crack region as a starting point, but it is difficult to achieve precise and efficient cleavage of hard substrates like sapphire with minimal external force
Solution Approach 1:
The patent divides the substrate surface into multiple regions and forms crack regions in a segmented manner using multiple pulse laser beams irradiated from different directions. This segmentation allows the crack to propagate more efficiently through the hard substrate with reduced external force, as each pulse contributes to creating a portion of the crack path rather than requiring a single high-force event.
Solution Approach 2:
The patent employs periodic pulsed laser irradiation where multiple pulses are applied in sequence from different directions. The periodic action of alternating laser pulses from different beams creates a cumulative effect that progressively extends the crack region through the substrate, enabling efficient cleavage of hard materials like sapphire with minimal external force.
2Productivity
If a pulse laser beam is used for dicing, then the workpiece can be cut, but elements such as LEDs formed on the substrate surface may be degraded during the dicing process
Solution Approach 1:
The patent applies laser irradiation locally to specific regions of the substrate surface where crack formation is needed, while avoiding direct irradiation of areas containing sensitive elements like LEDs. By controlling the irradiation positions and directions of multiple pulse laser beams, the crack regions are formed in targeted locations without degrading the functional elements on the substrate.
Solution Approach 2:
The patent performs preliminary crack region formation using multiple pulse laser beams before the actual cleavage process. This preliminary action creates the necessary crack pathways in advance, allowing the subsequent cleavage to proceed smoothly without requiring excessive force that could damage surface elements like LEDs.
3Force
If multiple pulse laser beams are used to form crack regions from different directions, then cleavage can be achieved with minimal external force, but the device complexity increases
Solution Approach 1:
The patent employs multiple pulse laser beams that can be positioned and directed from different angles to irradiate the substrate surface. These multiple beams serve the universal function of creating crack regions, allowing the system to achieve minimal external force requirement for cleavage while managing complexity through the coordinated action of multiple laser sources.
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 method enables excellent cleavage characteristics with good linearity, reduced cleaving force, and improved yield, while preventing degradation of elements like LEDs during the dicing process, especially for hard substrates like sapphire, by forming continuous cracks with optimized pulse laser beam conditions.
Implementation Method 1
a crack region is formed in a workpiece by an optical damage generated with a pulse laser beam
Data Source
AI summary
A laser dicing method includes: placing a workpiece substrate on a stage; generating a clock signal; emitting a pulse laser beam synchronous with the clock signal; switching irradiation and non-irradiation of the workpiece substrate with the pulse laser beam in a unit of light pulse in synchronization with the clock signal to perform first irradiation of the pulse laser beam on a first straight line by controlling the pulse laser beam using a pulse picker; performing second irradiation of the pulse laser beam on a second straight line, which is adjacent to the first straight line in a substantially parallel fashion, after the first irradiation; and forming a crack reaching a workpiece substrate surface on the workpiece substrate by the first irradiation and the second irradiation.